WO2022061821A1

WO2022061821A1 - Device and preparation method therefor, receiver chip, distance measuring device, and movable platform

Info

Publication number: WO2022061821A1
Application number: PCT/CN2020/118151
Authority: WO
Inventors: 王国才; 卢栋; 郑国光
Original assignee: 深圳市大疆创新科技有限公司
Priority date: 2020-09-27
Filing date: 2020-09-27
Publication date: 2022-03-31
Also published as: CN114631186A

Abstract

The present application provides a semiconductor device and a preparation method therefor, a receiver chip, a distance measuring device, and a movable platform. The semiconductor device comprises: an epitaxial layer which comprises a first surface and a second surface that are oppositely arranged; several avalanche photodiodes which are formed on the first surface of the epitaxial layer, incident light entering the avalanche photodiodes through the second surface of the epitaxial layer; several first electrodes which are formed on the first surface of the epitaxial layer at intervals and completely cover the avalanche photodiodes corresponding to the first electrodes vertically; and a second electrode comprising a heavily doped region formed on the second surface of the epitaxial layer. The semiconductor device solves the trailing problem caused by substrate photon-generated carrier diffusion and substrate impurity diffusion, and can improve the shielding effect of photon-generated carriers and reduce delays, while the quantum efficiency remains unchanged.

Description

Device and preparation method thereof, receiving chip, distance measuring device, and movable platform

manual

technical field

The present application generally relates to the field of integrated circuits, and more particularly, to a semiconductor device and a method for manufacturing the same, a receiving chip, a ranging device, and a movable platform.

Background technique

Lidar is a radar system that emits laser beams to detect the position, velocity and other characteristic quantities of targets. The photosensitive sensor of the lidar can convert the obtained optical pulse signal into an electrical signal, and obtain the time information corresponding to the electrical signal based on the comparator, thereby obtaining the distance information between the lidar and the target.

In the receiving chip of lidar, avalanche photodiode (APD), as a widely used photoelectric detection device, is notable for its ability to amplify the weak light signal inside the device through the photomultiplier effect, and the amplified signal can be It is recognized and collected by the post-stage circuit, so as to overcome the disadvantage that the traditional diode cannot effectively detect the weak light signal, and realize the detection of the weak light signal.

At present, due to the diffusion of photogenerated carriers generated by the substrate to the epitaxial layer, the APD device produces a tailing phenomenon during the photoresponse process. The performance of the laser radar device as a photoelectric receiving chip component causes problems such as blind spots in the vicinity of the laser radar.

Therefore, there is a need to improve current APD devices to overcome the above problems.

SUMMARY OF THE INVENTION

The present application has been made in order to solve the above-mentioned problems. A first aspect of the present application provides a semiconductor device, the semiconductor device comprising:

an epitaxial layer, comprising a first surface and a second surface arranged oppositely;

a plurality of avalanche photodiodes are formed on the first surface of the epitaxial layer, and incident light is incident on the avalanche photodiodes from the second surface of the epitaxial layer;

A plurality of first electrodes are formed on the first surface of the epitaxial layer at intervals and completely cover the avalanche photodiodes corresponding to the upper and lower sides thereof;

The second electrode includes a heavily doped region formed on the second surface of the epitaxial layer.

A second aspect of the present application provides a preparation method of a semiconductor device, the preparation method comprising:

providing a substrate formed with an epitaxial layer, the epitaxial layer comprising a first surface and a second surface disposed oppositely, the first surface of the epitaxial layer being away from the substrate;

A plurality of avalanche photodiodes are formed on the first surface of the epitaxial layer, wherein the incident light of the avalanche photodiodes is incident from the second surface of the epitaxial layer;

forming a heavily doped region on the second surface of the epitaxial layer to serve as a second electrode;

A plurality of first electrodes isolated from each other are formed on the first surface of the epitaxial layer to respectively cover the avalanche photodiodes below.

A third aspect of the present application provides a receiving chip, and the receiving chip includes:

The aforementioned semiconductor device is used to receive the optical pulse sequence reflected by the detected object, and convert the received optical pulse sequence into a current signal;

The signal processing unit is used for receiving and processing the current signal of the semiconductor device to output a time signal.

A fourth aspect of the present application provides a distance measuring device, the distance measuring device comprising:

Light emitting circuit for emitting light pulse sequence;

The aforementioned receiving chip is used to receive the optical pulse sequence reflected by the detected object, and output a time signal based on the received optical pulse sequence;

an arithmetic circuit for calculating the distance between the detected object and the distance measuring device according to the time signal.

A fifth aspect of the present application provides a movable platform, and the movable platform includes:

Movable platform body;

The distance measuring device described above, the distance measuring device is provided on the movable platform body;

A power system is used to drive the movable platform body to move.

The present application provides a back-illuminated semiconductor device in which incident light is incident on the avalanche photodiode from the second surface of the epitaxial layer. Wherein, the semiconductor device no longer includes a substrate, and at the same time, a heavily doped region is formed in the epitaxial layer as the second electrode, which improves the drag caused by the diffusion of photo-generated carriers in the substrate and the diffusion of impurities in the substrate. tail problem

Description of drawings

1A-1I show schematic cross-sectional views of each intermediate device in the semiconductor device fabrication process provided by the present application;

FIG. 2 shows a schematic flowchart of a method for manufacturing a semiconductor device provided by the present application;

FIG. 3 shows a schematic diagram of a detection device in an embodiment of the present application.

detailed description

In order to make the objectives, technical solutions and advantages of the present application more apparent, the exemplary embodiments according to the present application will be described in detail below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments of the present application, and it should be understood that the present application is not limited by the example embodiments described herein. Based on the embodiments of the present application described in the present application, all other embodiments obtained by those skilled in the art without creative efforts shall fall within the protection scope of the present application.

In the following description, numerous specific details are set forth in order to provide a more thorough understanding of the present application. It will be apparent, however, to one skilled in the art that the present application may be practiced without one or more of these details. In other instances, some technical features known in the art have not been described in order to avoid confusion with the present application.

It should be understood that the application may be embodied in different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of this application to those skilled in the art.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. As used herein, the singular forms "a," "an," and "the/the" are intended to include the plural forms as well, unless the context clearly dictates otherwise. It should also be understood that the terms "compose" and/or "include", when used in this specification, identify the presence of stated features, integers, steps, operations, elements and/or components, but do not exclude one or more other The presence or addition of features, integers, steps, operations, elements, parts and/or groups. As used herein, the term "and/or" includes any and all combinations of the associated listed items.

For a thorough understanding of the present application, detailed steps and detailed structures will be presented in the following description, so as to explain the technical solutions proposed by the present application. The preferred embodiments of the present application are described in detail below, however, the present application may have other embodiments in addition to these detailed descriptions.

As mentioned earlier, an Avalanche Photodiode (APD) is a metallurgical junction interface (PN junction) device operating in a reverse biased state. Its operating voltage is less than the junction breakdown voltage, and the device is depleted under the action of reverse bias. When excited by an external optical signal, the generated optical signal generates photo-generated carriers in the depletion region, and the photo-generated carriers are separated under the action of the external electric field and move to the anode and the cathode respectively. Under the action of the external electric field, the photogenerated carriers are accelerated. If enough energy is obtained under the action of the high electric field in the junction region, they can collide with the lattice, ionize the lattice, and generate new electron-hole pairs, thereby making the carrier The increase in the number of currents produces a multiplication effect, realizing the amplification and detection of weak signals.

Since the APD is prepared on the silicon-based epitaxial layer by process injection annealing, etc., for the front-illumination process, the front-side incident light will continue to enter the substrate after passing through the epitaxial layer, and photogenerated carriers will be generated in the substrate. Due to the high doping concentration of the substrate, the electric field in the substrate is almost completely cancelled. The photogenerated carriers generated in the substrate need to diffuse to the depletion region, and then reach the avalanche collection region under the action of the electric field. To a certain extent, the optical response signal of the device cannot change rapidly with the light input, resulting in the drag of the device. tail problem.

At present, the solution to avoid tailing caused by diffusion of photo-generated carriers in the substrate and diffusion of impurities in the substrate is to increase the doping concentration of the substrate, thereby reducing the lifetime of photo-generated carriers.

However, the inventor found that another main reason for the tailing phenomenon of the device is that after the electron-hole separation of photogenerated carriers under the action of the electric field in the depletion region, the separated electrons and holes will produce a reverse direction opposite to the direction of the external electric field. electric field, thereby shielding the effect of the external electric field. As a result, the newly generated photo-generated carriers cannot reach the saturation drift velocity under the action of the net electric field, thereby causing the device to smear. The research shows that the equivalent electric field strength E generated by the shielding effect satisfies the following formula:

E=IW _d /3V _d εS

Among them, ε is the dielectric constant, S is the area of the junction region or the photosensitive region, W _d is the width of the depletion region, V _d is the carrier saturation drift velocity, and I is the photocurrent magnitude.

That is to say, the inventors have found through analysis that increasing the doping of the substrate can reduce the delay caused by the diffusion of photo-generated carriers in the substrate and the diffusion of impurities in the substrate to a certain extent, but this method cannot shield the photo-generated carriers. effect is improved.

At the same time, in the APD preparation process, it is inevitable to use an annealing process, which will further cause the highly doped impurities in the substrate to diffuse into the epitaxial layer during the annealing process, resulting in the reduction of the electric field in the depletion zone in the epitaxial layer, thereby further reducing the epitaxial layer. Internal photogenerated carrier transfer speed, resulting in device delay.

However, the inventors found that in the process of preparing APD devices, although low temperature and long time annealing instead of high temperature annealing can be used to reduce the diffusion of substrate impurities to the epitaxial layer, this method cannot improve the shielding effect of photogenerated carriers.

Based on the above-mentioned problem of tailing caused by the diffusion of photo-generated carriers in the substrate and the diffusion of impurities in the substrate, the inventor proposed a solution to eliminate the substrate. Schemes for thin epitaxial layers.

Further, the inventors found that reducing the thickness of the epitaxial layer would lead to a decrease in the quantum efficiency of the APD device, which would affect the light-influenced characteristics of the APD device, thereby affecting the performance of the APD device.

Based on this, the inventor proposes that the optical path is doubled by the reflection effect of the first electrode on the epitaxial layer, and the original quantum efficiency can be maintained on the basis of reducing the actual path of photogenerated carriers, that is, the quantum efficiency can be maintained. Under the same condition, the shielding effect of photogenerated carriers is improved, and the delay is improved.

In this way, through the above-mentioned design, a semiconductor device and a preparation method thereof can be provided, which can avoid the diffusion of impurities in the substrate, and can reduce the tailing problem caused by the shielding effect of photogenerated carriers without affecting other performance indicators of the device. Improve the light response speed of the device and improve the tailing problem of the device.

Example 1

In order to solve the above problems, the present application provides a semiconductor device, as shown in FIG. 1I, the semiconductor device includes:

The epitaxial layer 102 includes a first surface and a second surface disposed oppositely;

A plurality of avalanche photodiodes 103 are formed on the first surface of the epitaxial layer 102, and incident light is incident on the avalanche photodiodes 103 from the second surface of the epitaxial layer 102;

A plurality of first electrodes 109 are formed on the first surface of the epitaxial layer 102 at intervals and completely cover the avalanche photodiodes 103 corresponding to the upper and lower sides thereof;

The second electrode 107 includes a heavily doped region formed on the second surface of the epitaxial layer 102 .

The epitaxial layer 102 can be made of semiconductor material, and in an embodiment of the present application, an epitaxial silicon wafer is selected.

Wherein, the epitaxial layer 102 includes a first surface and a second surface disposed opposite to each other, wherein the first surface is usually a front surface, and the second surface is usually a back surface.

In an embodiment of the present application, the semiconductor device is a back-illuminated device, that is, in the back-illuminated device, the photosensitive device APD is located in front of the circuit transistor, and light first enters the photosensitive device APD, thereby increasing the Sensitivity. In the present application, the APD is formed on the first surface of the epitaxial layer 102 , that is, the front surface of the epitaxial layer 102 , and the light enters from the back surface of the epitaxial layer 102 , that is, from the second surface of the epitaxial layer 102 . .

Optionally, the epitaxial layer 102 has a low doping type, and the doping type may be N-type or P-type. Generally, the epitaxial layer 102 is P-type doped.

Wherein, the final doping concentration of the epitaxial layer 102 is less than or equal to the initial doping concentration. In the embodiment of the present application, the epitaxial layer 102 includes a thinning process, such as removing the substrate 101 and removing a portion of the epitaxial layer 102 from the second surface of the epitaxial layer 102, wherein the removed portion includes the The top of the epitaxial layer 102 includes the region where the impurities in the substrate 101 are diffused. After removing the top of the epitaxial layer 102 including the impurity diffusion region in the substrate 101, the final doping concentration of the epitaxial layer 102 is less than or lower than the initial doping concentration, so as to reduce the generation of photogenerated carriers in the APD The consumption of the streamers, and then quickly reach the avalanche collection area of the APD, improve the corresponding speed of the APD, avoid the tailing problem of the APD, and avoid the delay of the device.

The thickness from the second surface of the epitaxial layer 102 to the first surface is 20 μm-40 μm. The thickness of the epitaxial layer 102 is thinner than the conventional thickness. By reducing the thickness of the epitaxial layer 102, the width of the depletion region can be reduced, so that the photogenerated carriers are separated from the electron holes under the action of the electric field in the depletion region. The intensity of the generated reverse electric field opposite to the external electric field is reduced, so that the newly generated photo-generated carriers can reach the saturation drift speed under the action of the net electric field, thereby improving the response speed of the device.

Wherein, the final doping concentration of the epitaxial layer 102 is less than or equal to 1×10 ¹⁵ /cm ³ . In the present application, setting the epitaxial layer 102 to a low-doped type can reduce the consumption of photogenerated carriers in the APD, thereby quickly reaching the avalanche collection area of the APD, and improving the corresponding speed of the APD, Avoid the tailing problem of APD and avoid the delay of the device.

In an embodiment of the present application, a plurality of avalanche photodiodes 103 are formed on the surface of the epitaxial layer 102 , for example, a plurality of rows or columns of avalanche photodiodes 103 are formed to form a linear array of avalanche photodiodes In another embodiment, multiple rows and multiple columns of avalanche photodiodes 103 are formed to form an avalanche photodiode area array. The number of the avalanche photodiodes 103 is not limited to a certain numerical range, and can A selection is required.

The avalanche photodiode 103 includes functional regions of the avalanche photodiode 103 formed sequentially from bottom to top on the first surface of the epitaxial layer 102 , and each functional region of the avalanche photodiode 103 includes a buffer layer and a diffusion barrier layer. , avalanche multiplication layer, absorption layer and contact layer, etc.

Further, an electric field control layer and a graded layer may be further formed between the avalanche multiplication layer and the absorption layer.

In an embodiment of the present application, the avalanche photodiode 103 includes, from bottom to top, a p-InP buffer layer, a p-AlInAs diffusion barrier layer, a low-doped n-InP avalanche multiplication layer, an n-InP electric field control layer, an n-InP -InGaAsP graded layer, nInGaAs light absorbing layer, semi-insulating InP window layer and InGaAs contact layer.

The doping concentration and thickness of each functional layer of the avalanche photodiode 103 may be conventional doping concentrations and thicknesses, which will not be listed one by one here.

A first isolation structure 104 is further formed on the first surface of the epitaxial layer 102 , and the first isolation structure 104 is disposed between the adjacent avalanche photodiodes for preventing the adjacent avalanche photodiodes 103 Bridging occurs to avoid short-circuiting of the device.

The doping type of the first isolation structure 104 is different from the doping type of the functional layer on the top of the avalanche photodiode 103 , that is, the doping type of the contact layer on the top of the avalanche photodiode 103 is different.

The ion implantation energy and concentration of the first isolation structure 104 are not limited to a certain value range, and can be selected according to actual needs.

Further, a second isolation structure 105 is formed on the epitaxial layer 102 for isolating the avalanche photodiodes 103 and preventing signal crosstalk between the avalanche photodiodes 103 . The first isolation structure 104 is disposed between the avalanche photodiode 103 and the second isolation structure 105 .

In the embodiment of the present application, in the preparation method, the second isolation structure 105 is formed by ion implantation.

The ion type of the second isolation structure 105 is the same as the doping type of the top functional layer of the avalanche photodiode 103 , and is different from the ion type implanted by the first isolation structure 104 . Wherein, the second isolation structure 105 is optional and not necessary, and the first isolation structure 104 may exist independently in the semiconductor device.

In an embodiment of the present application, the doping type of the epitaxial layer 102 is low P-type doping, the doping type of the contact layer on the top of the avalanche photodiode 103 is N-type doping, and the first isolation The doping type of the structure 104 is P-type doping, and the doping type of the second isolation structure 105 is N-type doping.

In another embodiment of the present application, the doping type of the epitaxial layer 102 is low N-type doping, the doping type of the contact layer on top of the avalanche photodiode 103 is P-type doping, the first The doping type of the isolation structure 104 is N-type doping, and the doping type of the second isolation structure 105 is P-type doping.

A heavily doped region is formed on the second surface of the epitaxial layer 102 to serve as the second electrode 107 .

Among them, in the embodiment of the present application, through low-energy ion implantation, and implanting high-concentration impurities, and finally performing rapid annealing to form the second electrode 107 as an anode, through the improvement, the substrate impurities and impurities can be directly eliminated. Smearing effect caused by diffusion of photogenerated carriers within the substrate.

Optionally, the energy of the ion implantation in the heavily doped region is 5Kev-50Kev; for example, in a specific embodiment, impurities are implanted at an energy of about 10keV.

The type of the implanted impurities is the same as the doping type of the epitaxial layer 102. For example, in an embodiment of the present application, the doping type of the epitaxial layer 102 is P-type, then in this step, the re-doping type is The type of impurity implanted in the impurity region is P-type.

Wherein, the concentration of the ion implantation is relatively high and has a relatively thin thickness to prevent ion diffusion and can play the role of connecting electrodes, and the depth of the ion implantation is less than 1 μm; and/or the concentration of the ion implantation The range is greater than 5×10 ¹⁸ /cm ³ .

In an embodiment of the present application, the concentration range of the ion implantation is 5×10 ¹⁸ /cm ³ to 5×10 ²⁰ /cm ³ .

A transparent carrying structure 108 is disposed on the second electrode 107 to cover the second electrode 107 to support and protect the epitaxial layer 102 and the devices formed in the epitaxial layer 102 .

The carrying structure 108 is made of a light-transmitting material to ensure that light can pass through the carrying structure 108 and be transmitted to the reflective surface of the first electrode 109 in the subsequent steps. Wherein, the light-transmitting material is not limited to a certain one, and the material of the bearing structure 108 may be a semiconductor material, such as a silicon wafer, or glass, etc. In an embodiment of the present application, the bearing structure 108 is a carrier wafer or carrier glass.

A plurality of first electrodes 109 isolated from each other are formed on the first surface of the epitaxial layer 102, and the first electrodes 109 completely shield the APD avalanche region.

The first electrode 109 not only plays the role of electrical connection as the electrode of the APD, in the embodiment of the present application, the first electrode 109 also has a reflective surface, through which the epitaxial layer will be removed from the epitaxial layer. Light incident on the second surface of the epitaxial layer 102 is reflected to the second surface of the epitaxial layer 102 .

Optionally, the first electrode 109 is a metal layer with a reflective surface, for example, a copper layer, an aluminum layer and the like can be formed.

The method for forming the first electrode 109 may be to form a first electrode material layer, and then etch the first electrode material layer to form a plurality of first electrodes 109 isolated from each other, wherein the etching method It can be dry etching or wet etching.

In the embodiment of the present application, the thickness of the epitaxial layer is thinner than that of the conventional epitaxial layer, which can reduce the width of the depletion region, thereby eliminating the shielding effect and improving the response speed of the device, but the quantum efficiency of the avalanche photodiode The thickness of the epitaxial layer is positively correlated. When the thickness of the epitaxial layer is reduced, the quantum efficiency of the avalanche photodiode will decrease. Therefore, in order to eliminate the quantum efficiency caused by the thinning of the thickness of the epitaxial layer. Adverse effects, a reflective surface is provided on the surface of the first electrode, so that the light incident from the second surface of the epitaxial layer is reflected to the second surface of the epitaxial layer, as shown in FIG. The signal light incident on the surface (back side) will double the optical path due to the reflection of the first electrode. For example, the thickness of the epitaxial layer of 25um can be equivalent to the thickness of the epitaxial layer of 50um, so the actual path of photogenerated carriers is reduced. On the basis of half of the quantum efficiency, the original quantum efficiency can be maintained, that is, the shielding effect of photogenerated carriers can be improved and the delay can be improved while keeping the quantum efficiency unchanged.

Further, the first electrode 109 not only completely blocks the APD avalanche region, but also further covers the second isolation structure 105 to reflect the light entering the epitaxial layer 102, thereby preventing excessive optical signals from entering In the epitaxial layer 102 , the epitaxial layer 102 is heated to avoid affecting the performance of the avalanche photodiode 103 .

The semiconductor device described in the present application no longer includes a substrate, and at the same time, a heavily doped region is formed in the thinned epitaxial layer as the second electrode, which improves the diffusion of photo-generated carriers in the substrate and the diffusion of impurities in the substrate. caused the tailing problem. Further, the semiconductor device described in the present application is a back-illuminated structure, and incident light is incident on the avalanche photodiode from the second surface of the epitaxial layer, thereby improving the shielding effect of photo-generated carriers and improving the retardation.

Embodiment 2

In order to solve the technical problems mentioned above, the present application also provides a method for preparing a semiconductor device, as shown in FIG. 2 , the preparation method specifically includes the following steps:

Step S1: providing a substrate formed with an epitaxial layer, the epitaxial layer comprising a first surface and a second surface disposed opposite to each other, and the first surface of the epitaxial layer is away from the substrate;

Step S2: forming a plurality of avalanche photodiodes on the first surface of the epitaxial layer, wherein the incident light of the avalanche photodiodes is incident from the second surface of the epitaxial layer;

Step S3: forming a heavily doped region on the second surface of the epitaxial layer as a second electrode;

Step S4: forming a plurality of mutually isolated first electrodes on the first surface of the epitaxial layer to respectively cover the avalanche photodiodes below

The preparation method will be described in detail below with reference to FIGS. 1A-1I , wherein FIGS. 1A-1I show schematic cross-sectional views of each intermediate device in the process of preparing the semiconductor device provided by the present application.

In the step S1, as shown in FIG. 1A, a substrate 101 having an epitaxial layer 102 is provided, wherein the substrate 101 may be at least one of the following materials: silicon, silicon-on-insulator ( SOI), silicon on insulator (SSOI), silicon germanium on insulator (S-SiGeOI), silicon germanium on insulator (SiGeOI), germanium on insulator (GeOI), etc.

In an embodiment of the present application, the substrate 101 is made of silicon.

The initial thickness of the epitaxial layer 102 is greater than 50 μm to ensure that the epitaxial layer 102 with the target thickness is obtained after the epitaxial layer 102 is thinned.

The epitaxial layer 102 includes a first surface and a second surface disposed opposite to each other, the second surface of the epitaxial layer 102 is disposed on the substrate 101, and the first surface of the epitaxial layer 102 is far away from the substrate Bottom 101. Wherein, the first surface is a front surface, and the second surface is a back surface.

In an embodiment of the present application, the semiconductor device is a back-illuminated device, that is, in the back-illuminated device, the photosensitive device APD is located in front of the circuit transistor, and light first enters the photosensitive device APD, thereby increasing the Sensitivity. In this application, the APD is formed on the first surface of the epitaxial layer 102 , that is, the front surface of the epitaxial layer 102 , and the light is taken in from the back surface of the epitaxial layer 102 , that is, the light enters from the second surface of the epitaxial layer 102 .

Optionally, the epitaxial layer 102 has a low doping type, and the doping type may be N-type or P-type. Generally, the epitaxial layer 102 is P-type doped. When the epitaxial layer 102 is doped, due to ion diffusion , annealing and other processes usually make the doping concentration smaller than the initial doping concentration, so the final doping concentration of the epitaxial layer 102 is less than or equal to the initial doping concentration.

In the embodiment of the present application, the partial area of the second surface of the epitaxial layer 102 that is in contact with the substrate 101 may cause the diffusion of ions in the substrate 101 to cause the epitaxial layer 102 The doping concentration of some regions has changed, so in the subsequent steps, it is necessary to remove the region where the impurity diffused in the substrate 101 is located on the top of the second surface of the epitaxial layer 102 to ensure the final The doping concentration is less than or equal to the initial doping concentration.

Wherein, the final doping concentration of the epitaxial layer 102 is less than or equal to 1×10 ¹⁵ /cm ³ .

In the present application, setting the epitaxial layer 102 to a low-doped type can reduce the consumption of photogenerated carriers in the APD, thereby quickly reaching the avalanche collection area of the APD, and improving the corresponding speed of the APD, Avoid the tailing problem of APD and avoid the delay of the device.

In the step S2, as shown in FIG. 1B, a plurality of avalanche photodiodes 103 are formed on the first surface of the epitaxial layer 102 (the front surface of the epitaxial layer).

In an embodiment of the present application, a plurality of avalanche photodiodes 103 are formed on the surface of the epitaxial layer 102. In an embodiment, for example, a plurality of rows or columns of avalanche photodiodes 103 are formed to form the avalanche photodiodes. A linear array of diodes, in another embodiment, multiple rows and multiple columns of avalanche photodiodes 103 are formed to form an avalanche photodiode array. A choice is actually required.

An ion implantation process is performed on the first surface of the epitaxial layer 102 , and each functional region of the avalanche photodiode 103 is sequentially formed on the first surface of the epitaxial layer 102 from bottom to top, and each functional region of the avalanche photodiode 103 Including buffer layer, diffusion barrier layer, avalanche multiplication layer, absorption layer and contact layer.

A first isolation structure 104 is further formed on the first surface of the epitaxial layer 102 , and the first isolation structure 104 is disposed between the adjacent avalanche photodiodes 103 for preventing adjacent avalanche photodiodes 103 is bridged to avoid short circuit of the device.

Wherein, there is no specific requirement for the formation sequence of the avalanche photodiode 103 , the first isolation structure 104 and the second isolation structure 105 . For example, in an embodiment of the present application, the avalanche photodiode is formed first. 103 , the first isolation structure 104 is then formed, and finally the second isolation structure 105 is formed. For example, in another embodiment of the present application, the ion type of the second isolation structure 105 is the same as that of the avalanche photodiode 103 The doping type of the top functional layer is the same, so the top of the avalanche photodiode 103 and the second isolation structure 105 can be formed at the same time, and the first isolation structure 104 is formed before or after this, and they are not one by one here. enumerate.

The preparation method further includes: bonding the carrier wafer 106 on the first surface of the epitaxial layer 102 to cover the first surface for supporting and protecting in the subsequent thinning process, as shown in FIG. 1C is shown.

Wherein, the carrier wafer 106 can be selected from semiconductor materials commonly used in the field, which is not limited herein, as long as it can play a supporting and protecting role in the subsequent thinning process.

Wherein, the epitaxial layer 102 and the carrier wafer 106 may be temporarily bonded by an adhesive, or temporarily bonded by a high-temperature bonding process, so that the epitaxial layer 102 and the carrier wafer 106 are bonded as one.

After the epitaxial layer 102 and the carrier wafer 106 are bonded, the bonded intermediate device is flipped.

The preparation method further includes: thinning the epitaxial layer 102 so that the thickness from the second surface of the epitaxial layer 102 to the first surface after the thinning is a target thickness, as shown in FIG. 1D .

Specifically, in this step, the substrate 101 and a part of the epitaxial layer 102 are removed, wherein the top of the removed part of the epitaxial layer 102 includes a region where impurities in the substrate 101 are diffused. By removing the top of the epitaxial layer 102 including the impurity diffusion region in the substrate 101, the final doping concentration of the epitaxial layer 102 is less than or lower than the initial doping concentration, so as to reduce the generation of photogenerated in the APD. The consumption of carriers, and then quickly reach the avalanche collection area of the APD, improve the corresponding speed of the APD, avoid the tailing problem of the APD, and avoid the delay of the device.

Wherein, the thinning process may include one or a combination of chemical mechanical masking, planarization treatment and polishing.

Wherein, the initial thickness of the epitaxial layer 102 is greater than 50 μm, and the thickness from the second surface of the epitaxial layer 102 to the first surface after thinning is 20 μm-40 μm. By reducing the thickness of the epitaxial layer 102, the width of the depletion region can be reduced, so that the strength of the reverse electric field opposite to the external electric field generated by the separation of electron holes of photogenerated carriers under the action of the electric field in the depletion region can be reduced. small, so that the newly generated photo-generated carriers can reach the saturation drift speed under the action of the net electric field and improve the response speed of the device.

In the step S3 , as shown in FIG. 1E , a heavily doped region is formed on the second surface of the epitaxial layer 102 after thinning to serve as the second electrode 107 .

In the embodiment of the present application, the method for forming the second electrode 107 includes:

Ion implantation is performed on the second surface of the epitaxial layer 102 to form a heavily doped region as the second electrode 107 . Among them, in the embodiment of the invention, the second electrode 107 is formed by low-energy ion implantation, and high-concentration impurities are implanted, and finally, rapid annealing is performed to form the second electrode 107 as an anode. Through the improvement of the method, the substrate impurities can be directly eliminated. and the tailing effect caused by the diffusion of photogenerated carriers in the substrate.

Optionally, the implantation impurities are implanted at low energy by an ion implanter, and the implantation impurity diffusion is reduced by lowering the implantation energy. Specifically, the energy of ion implantation on the second surface of the epitaxial layer 102 is 5Kev-50Kev; for example, in a specific embodiment, impurities are implanted at an energy of about 10keV.

Wherein, the concentration of the ion implantation is relatively high and has a thin thickness to prevent ion diffusion and can play the role of connecting electrodes, and the depth of the ion implantation is less than 1 μm; and/or the concentration range of the ion implantation More than 5×10 ¹⁸ /cm ³ .

Further, after the ion implantation, the method further includes the step of performing rapid annealing to prevent impurity diffusion.

In an embodiment of the present application, the temperature of the rapid annealing is 800°C-1600°C; the time of the rapid annealing is 10s-300s.

In this step, the method further includes the step of removing the carrier wafer. After the second electrode 107 is formed and before the carrier wafer 106 is removed, the method further includes: bonding on the second electrode 107 A light-transmitting carrier structure 108 , as shown in FIG. 1F , covers the second electrode 107 so as to protect the epitaxial layer 102 and the devices formed in the epitaxial layer 102 after the carrier wafer 106 is removed. Support and protect.

After the carrier structure 108 is formed, the carrier wafer 106 is removed. Wherein, the removal method is debonding, for example, a high temperature method can be used, or a chemical reagent can be dropped to separate the carrier wafer 106 from the epitaxial layer 102 , as shown in FIG. 1G .

In the step S4 , as shown in FIG. 1H , the intermediate device obtained in the step S3 is turned over so that the first surface faces upward, and then a plurality of mutual isolations are formed on the first surface of the epitaxial layer 102 The first electrode 109 completely blocks the APD avalanche region.

In the embodiment of the present application, the width of the depletion region can be reduced by reducing the thickness of the epitaxial layer 102, thereby eliminating the shielding effect and improving the response speed of the device, but the quantum efficiency of the avalanche photodiode 103 is the same as the The thickness of the epitaxial layer 102 is positively correlated. When the thickness of the epitaxial layer 102 is reduced, the quantum efficiency of the avalanche photodiode 103 will decrease. To avoid the adverse effect of quantum efficiency, a reflective surface is provided on the surface of the first electrode 109 to reflect the light incident from the second surface of the epitaxial layer 102 to the second surface of the epitaxial layer 102, as shown in FIG. 1I As shown, the signal light incident from the second surface (back surface) will double the optical path due to the reflection effect of the first electrode 109. For example, the thickness of the epitaxial layer 102 of 25um can be equivalent to the thickness of the epitaxial layer 102 of 50um. Therefore, On the basis of halving the actual path of photogenerated carriers, the original quantum efficiency can be maintained, that is, the shielding effect of photogenerated carriers can be improved and the delay can be improved while keeping the quantum efficiency unchanged.

Further, the first electrode 109 not only completely blocks the APD avalanche region, but also further covers the second isolation structure 105 to reflect the light entering the epitaxial layer, thereby preventing excessive optical signals from entering the In the epitaxial layer, the epitaxial layer is heated to avoid affecting the performance of the avalanche photodiode 103 .

The semiconductor device obtained by the preparation method described in the present application no longer includes a substrate, and at the same time, a heavily doped region is formed in the epitaxial layer by low-energy and high-dose implantation as the second electrode, which improves the photo-generated current caused by the substrate. The problem of tailing caused by sub-diffusion and substrate impurity diffusion. Further, the semiconductor device described in the present application is a back-illuminated structure, the incident light is incident on the avalanche photodiode from the second surface of the epitaxial layer, and the width of the depletion region can be reduced by reducing the thickness of the epitaxial layer, In this way, the shielding effect is eliminated, the response speed of the device is improved, and the optical path is doubled through the reflection effect of the first electrode, and the original quantum efficiency is maintained on the basis of reducing the actual path of photogenerated carriers, that is, it can be Under the condition of keeping the quantum efficiency unchanged, the shielding effect of photogenerated carriers is improved, and the delay is improved.

Embodiment 3

The present application also provides a receiving chip, wherein the receiving chip includes:

The aforementioned semiconductor device is used to receive the optical pulse sequence reflected by the detected object, and convert the received optical pulse sequence into a current signal.

The receiving chip further includes a signal processing unit for receiving and processing the current signal of the semiconductor device to output a time signal.

Wherein, the semiconductor device is located in a chip, the signal processing unit is located in a signal processing chip, and the two chips are correspondingly connected electrically, so as to transmit the current signal to the signal processing unit for processing.

The signal processing unit integrates a plurality of circuits. In an embodiment of the present application, for example, the signal processing unit integrates a transimpedance amplifier circuit (TIA circuit), a multi-stage operational amplifier OPA, a comparator, and a time-to-digital converter (time-to-digital converter). A circuit converted into a digital signal) or an analog-to-digital conversion circuit (ADC circuit), and a subsequent data processing circuit (DSP circuit). Among them, the TIA circuit is an analog front-end circuit that converts the APD photocurrent into a voltage.

Wherein, when the semiconductor device converts the optical signal into a current signal, an external high-voltage power supply is required, and the APD can provide a stable internal gain and improve the signal-to-noise ratio, and output the current signal.

In the signal processing unit, the TIA circuit is electrically connected to the semiconductor device, the TIA circuit converts the current signal of the APD into a voltage signal, and provides a conversion gain at the same time; the multi-stage operational amplifier OPA is electrically connected to the TIA circuit It is connected to amplify the signal output by the TIA circuit to meet the comparison amplitude requirement of the comparator. The comparator is electrically connected to the multi-stage operational amplifier OPA, wherein a comparison threshold is set in the comparator to trigger the analog signal, convert the analog signal into a digital signal, and transmit the signal to the TDC circuit, and the TDC circuit is used to convert the analog signal into a digital signal. The digital signal is converted to a time signal for distance calculation. Wherein, for multiple signal processing units, one TDC circuit may be shared, that is, the number of signal processing units may not correspond to the number of TDC circuits.

A storage system may be further provided in the signal processing unit to cache data, provide input and output buffer space for the interface, and provide space for internal calculation.

An interface can be further set in the signal processing unit to serve as a data input and output channel to output the measurement data.

In a specific embodiment of the present application, the first input terminal of the comparator is used to receive the electrical signal input from the amplifiers across the group, that is, the electrical signal after the amplification operation, and the second input terminal of the comparator is used to receive the preset Threshold, the output end of the comparator is used to output the result of the comparison operation, wherein the result of the comparison operation includes time information corresponding to the electrical signal. It can be understood that the preset threshold value received by the second input end of the comparator may be an electrical signal whose intensity is the preset threshold value. The result of the comparison operation may be a digital signal corresponding to the electric signal after the amplification operation.

Optionally, the time-to-digital converter (Time-to-Digital Converter, TDC) is electrically connected to the output end of the comparator, and is used for extracting time information corresponding to the electrical signal according to the result of the comparison operation output by the comparator.

The receiving chip uses the above-mentioned semiconductor device, which improves the tailing problem caused by the diffusion of photo-generated carriers in the substrate and the diffusion of impurities in the substrate, and can improve the photo-generated carriers while keeping the quantum efficiency unchanged. The shielding effect of the current, improves the delay.

Further, when the front-illuminated semiconductor device is connected to the processing chip, since the photosensitive area and the processing circuit cannot be formed on the same layer, they can generally be connected by wire, but once the area of the array is large, the wire connection is easy to cause In this way, small arrayed front-illuminated semiconductor devices can have good applications, but medium and large ones are poor in practical applications. Compared with the front-illuminated type, the back-illuminated semiconductor device has a different surface from the lead-out surface and the light-sensitive surface, so it is avoided that the light-sensitive area will not be reduced when it is electrically connected to the processing chip, nor will it cause Mutual interference, and electrical connection is realized by means other than wire connection, which further avoids the problem of blocking light or mutual interference.

Embodiment 4

The present application also provides a ranging device. The semiconductor device or the receiving chip provided in each embodiment of the present application can be applied to the ranging device, and the ranging device can be an electronic device such as a laser radar or a laser ranging device. In one embodiment, the ranging device is used to sense external environmental information, for example, distance information, orientation information, reflection intensity information, speed information and the like of environmental objects. In an implementation manner, the ranging device can detect the distance from the detected object to the ranging device by measuring the light propagation time between the ranging device and the detected object, that is, Time-of-Flight (TOF). Alternatively, the ranging device can also detect the distance from the detected object to the ranging device through other technologies, such as a ranging method based on phase shift measurement, or a ranging method based on frequency shift measurement. This does not limit.

The distance measuring device of the present application includes the semiconductor device provided in each of the foregoing embodiments. In the semiconductor device, the first electrode acts as a metal reflective surface, thereby reflecting incident light, achieving metal connection and increasing quantum efficiency. Among them, the signal-to-noise ratio (SIGNAL NOISE RATIO, SNR or S/N) is proportional to the root N times of the quantum efficiency. Therefore, the semiconductor devices provided in the foregoing embodiments increase the noise-to-noise ratio for the entire ranging device, increased its range.

In addition, with the semiconductor device provided in the foregoing embodiments, the size of the chip used for integrating the semiconductor device will become smaller, and will become about 1/2 or 1/3 of the original size; further, the semiconductor device described in The avalanche photodiode is not only miniaturized, but also an array-level device with an area array structure. It is a solid-state laser radar, so it does not need to be scanned by mechanical rotation. Instead, it directly emits a pulsed laser that can cover the detection area in a short time. The highly sensitive area array receiving chip receives the echo signal, and completes the detection and perception of the surrounding environment distance information through a camera-like mode.

Wherein, the ranging device may be a mechanical rotating laser radar or a solid-state laser radar. In the mechanical rotating laser radar, mechanical rotation is used to change the optical path for scanning, and the solid-state laser radar can be directly transmitted in a short time. A pulsed laser that can cover the detection area is generated, and then a highly sensitive area array receiving chip is used to receive the echo signal, and the detection and perception of the distance information of the surrounding environment are completed by a mode similar to the camera taking pictures.

The following describes in detail that the ranging device is a mechanical rotating laser radar. For ease of understanding, the working process of ranging by the ranging device is described as an example below.

The ranging device may include a transmitting circuit, a receiving chip and an arithmetic circuit. Wherein, the receiving chip includes the aforementioned semiconductor device and the signal processing unit.

Wherein, in the signal processing unit, each signal processing unit may be provided with a transimpedance amplifier circuit (TIA circuit) independently, wherein the time-to-digital converter (TDC) may be provided independently, and a plurality of transimpedance amplifier circuits ( TIA circuits) share one of the time-to-digital converters (TDCs), and the time-to-digital converters (TDCs) can switch to different channels to receive and process signals from the transimpedance amplifier circuits (TIA circuits).

Wherein, the operation circuit may also be set independently or a plurality of the signal processing units may share one of the operation circuit.

The transmit circuit may transmit a sequence of optical pulses (eg, a sequence of laser pulses). The receiving chip can receive the optical pulse sequence reflected by the detected object, and output a time signal based on the received optical pulse sequence. The arithmetic circuit may determine the distance between the distance measuring device and the detected object based on the time signal.

Optionally, the distance measuring device may further include a control circuit, which can control other circuits, for example, can control the working time of each circuit and/or set parameters for each circuit.

In some implementation manners, the ranging device may further include a scanning module, configured to change the propagation direction of at least one laser pulse sequence emitted from the transmitting circuit to emit.

Wherein, a module including a transmitting circuit, a receiving chip, and an arithmetic circuit, or a module including a transmitting circuit, a receiving chip, an arithmetic circuit, and a control circuit may be called a ranging module, and the ranging module may be independent of other modules, for example, Scan module.

A coaxial optical path may be used in the ranging device, that is, the light beam emitted by the ranging device and the reflected light beam share at least part of the optical path in the ranging device. For example, after at least one laser pulse sequence emitted by the transmitting circuit changes its propagation direction through the scanning module, the laser pulse sequence reflected by the detection object passes through the scanning module and then enters the receiver. Alternatively, the distance-measuring device may also adopt an off-axis optical path, that is, the light beam emitted by the distance-measuring device and the reflected light beam are respectively transmitted along different optical paths in the distance-measuring device. FIG. 3 shows a schematic diagram of an embodiment in which the distance measuring device of the present application adopts a coaxial optical path.

The ranging apparatus 200 includes a ranging module 210, and the ranging module 210 includes a transmitter 203 (which may include the above-mentioned transmitting circuit), a collimating element 204, and a detector 205 (the receiving chip may include the detector 205, and the detector 205 includes the above descriptions) the semiconductor device) and the optical path changing element 206. The ranging module 210 is used for emitting a light beam, receiving the returning light, and converting the returning light into an electrical signal. Among them, the transmitter 203 can be used to transmit a sequence of optical pulses. In one embodiment, the transmitter 203 may emit a sequence of laser pulses. Optionally, the laser beam emitted by the transmitter 203 is a narrow bandwidth beam with a wavelength outside the visible light range. The collimating element 204 is disposed on the outgoing light path of the transmitter 203 for collimating the light beam emitted from the transmitter 203, and collimating the light beam emitted by the transmitter 203 into parallel light and outputting to the scanning module. The collimating element also serves to converge at least a portion of the return light reflected by the probe. The collimating element 204 may be a collimating lens or other elements capable of collimating light beams.

In the embodiment shown in FIG. 3 , the transmitting optical path and the receiving optical path in the ranging device are combined by the optical path changing element 206 before the collimating element 204, so that the transmitting optical path and the receiving optical path can share the same collimating element, so that the optical path more compact. In some other implementations, the emitter 203 and the detector 205 may use respective collimating elements, and the optical path changing element 206 may be arranged on the optical path behind the collimating element.

In the embodiment shown in FIG. 3 , since the beam aperture of the light beam emitted by the transmitter 203 is relatively small, and the beam aperture of the return light received by the ranging device is relatively large, the optical path changing element can use a small-area reflective mirror to The transmit light path and the receive light path are combined. In some other implementations, the optical path changing element may also use a reflector with a through hole, wherein the through hole is used to transmit the outgoing light of the emitter 203 , and the reflector is used to reflect the return light to the detector 205 . This can reduce the shielding of the return light by the bracket of the small reflector in the case of using a small reflector.

In the embodiment shown in FIG. 3 , the optical path changing element is offset from the optical axis of the collimating element 204 . In some other implementations, the optical path altering element may also be located on the optical axis of the collimating element 204 .

The ranging device 200 further includes a scanning module 202 . The scanning module 202 is placed on the outgoing optical path of the ranging module 210 . The scanning module 202 is used to change the transmission direction of the collimated beam 219 emitted by the collimating element 204 and project it to the external environment, and project the return light to the collimating element 204 . The returned light is focused on the detector 205 through the collimating element 204 .

In one embodiment, the scanning module 202 can include at least one optical element for changing the propagation path of the light beam, wherein the optical element can change the propagation path of the light beam by reflecting, refracting, diffracting the light beam, or the like. For example, the scanning module 202 includes lenses, mirrors, prisms, gratings, liquid crystals, optical phased arrays (Optical Phased Array) or any combination of the above optical elements. In one example, at least part of the optical elements are moving, for example, the at least part of the optical elements are driven to move by a driving module, and the moving optical elements can reflect, refract or diffract the light beam to different directions at different times. In some embodiments, the multiple optical elements of the scanning module 202 may be rotated or oscillated about a common axis 209, each rotating or oscillating optical element being used to continuously change the propagation direction of the incident beam. In one embodiment, the plurality of optical elements of the scanning module 202 may rotate at different rotational speeds, or vibrate at different speeds. In another embodiment, at least some of the optical elements of scan module 202 may rotate at substantially the same rotational speed. In some embodiments, the plurality of optical elements of the scanning module may also be rotated about different axes. In some embodiments, the plurality of optical elements of the scanning module may also rotate in the same direction, or rotate in different directions; or vibrate in the same direction, or vibrate in different directions, which are not limited herein.

In one embodiment, the scanning module 202 includes a first optical element 214 and a driver 216 connected to the first optical element 214, and the driver 216 is used to drive the first optical element 214 to rotate around the rotation axis 209, so that the first optical element 214 changes The direction of the collimated beam 219. The first optical element 214 projects the collimated beam 219 in different directions. In one embodiment, the angle between the direction of the collimated light beam 219 changed by the first optical element and the rotation axis 209 changes with the rotation of the first optical element 214 . In one embodiment, the first optical element 214 includes a pair of opposing non-parallel surfaces through which the collimated beam 219 passes. In one embodiment, the first optical element 214 includes a prism of varying thickness along at least one radial direction. In one embodiment, the first optical element 214 includes a wedge prism that refracts the collimated light beam 219 .

In one embodiment, the scanning module 202 further includes a second optical element 215 , the second optical element 215 rotates around the rotation axis 209 , and the rotation speed of the second optical element 215 is different from the rotation speed of the first optical element 214 . The second optical element 215 is used to change the direction of the light beam projected by the first optical element 214 . In one embodiment, the second optical element 215 is connected to another driver 217, and the driver 217 drives the second optical element 215 to rotate. The first optical element 214 and the second optical element 215 can be driven by the same or different drivers, so that the rotational speed and/or steering of the first optical element 214 and the second optical element 215 are different, thereby projecting the collimated beam 219 into the external space Different directions can scan a larger spatial range. In one embodiment, the controller 218 controls the

drivers

216 and 217 to drive the first optical element 214 and the second optical element 215, respectively. The rotational speeds of the first optical element 214 and the second optical element 215 may be determined according to the area and pattern expected to be scanned in practical applications.

Drives

216 and 217 may include motors or other drives.

In one embodiment, the second optical element 215 includes a pair of opposing non-parallel surfaces through which the light beam passes. In one embodiment, the second optical element 215 comprises a prism whose thickness varies along at least one radial direction. In one embodiment, the second optical element 215 comprises a wedge prism.

In one embodiment, the scanning module 202 further includes a third optical element (not shown) and a driver for driving the movement of the third optical element. Optionally, the third optical element includes a pair of opposing non-parallel surfaces through which the light beam passes. In one embodiment, the third optical element comprises a prism of varying thickness along at least one radial direction. In one embodiment, the third optical element comprises a wedge prism. At least two of the first, second and third optical elements rotate at different rotational speeds and/or rotations.

The rotation of each optical element in the scanning module 202 can project light in different directions, such as the direction 213 , so as to scan the space around the ranging device 200 . As shown in FIG. 4 , FIG. 4 is a schematic diagram of a scanning pattern of the distance measuring device 200 . It can be understood that when the speed of the optical element in the scanning module changes, the scanning pattern also changes accordingly.

When the light 211 projected by the scanning module 202 hits the detected object 201 , a part of the light is reflected by the detected object 201 to the distance measuring device 200 in a direction opposite to the projected light 211 . The returning light 212 reflected by the probe 201 passes through the scanning module 202 and then enters the collimating element 204 .

A detector 205 is placed on the same side of the collimating element 204 as the emitter 203, and the detector 205 is used to convert at least part of the return light passing through the collimating element 204 into an electrical signal.

In one embodiment, each optical element is coated with an anti-reflection coating. Optionally, the thickness of the anti-reflection film is equal to or close to the wavelength of the light beam emitted by the emitter 203, which can increase the intensity of the transmitted light beam.

In one embodiment, a filter layer is coated on the surface of an element located on the beam propagation path in the distance measuring device, or a filter is provided on the beam propagation path for transmitting at least the wavelength band of the light beam emitted by the transmitter, Reflect other bands to reduce noise from ambient light to the receiver chip.

In some embodiments, the transmitter 203 may comprise a laser diode through which laser pulses are emitted on the nanosecond scale. Further, the laser pulse receiving time can be determined, for example, by detecting the rising edge time and/or the falling edge time of the electrical signal pulse to determine the laser pulse receiving time. In this way, the ranging apparatus 200 can calculate the TOF by using the pulse receiving time information and the pulse sending time information, so as to determine the distance from the probe 201 to the ranging apparatus 200 .

Embodiment 5

The distance and orientation detected by the ranging device can be used for remote sensing, obstacle avoidance, mapping, modeling, navigation, etc., such as realizing the perception of the surrounding environment, and performing two-dimensional or three-dimensional mapping of the external environment. In one embodiment, the distance measuring device of the embodiment of the present application can be applied to the movable platform.

Based on this, the present application also provides a movable platform, wherein the distance measuring device described above can be applied to the movable platform, and the distance measuring device can be installed on the movable platform body of the movable platform.

In some embodiments, the movable platform includes at least one of an unmanned aerial vehicle, a car, a remote control car, a robot, and a camera. When the ranging device is applied to the unmanned aerial vehicle, the movable platform body is the fuselage of the unmanned aerial vehicle. When the distance measuring device is applied to an automobile, the movable platform body is the body of the automobile. The vehicle may be an autonomous driving vehicle or a semi-autonomous driving vehicle, which is not limited herein. When the distance measuring device is applied to the remote control car, the movable platform body is the body of the remote control car. When the distance measuring device is applied to the robot, the movable platform body is the body of the robot. When the ranging device is applied to the camera, the movable platform body is the body of the camera.

In some embodiments, the movable platform may further include a power system for driving the movable platform body to move. For example, when the movable platform is a vehicle, the power system may be an engine inside the vehicle, which will not be listed here.

Although example embodiments have been described herein with reference to the accompanying drawings, it should be understood that the above-described example embodiments are exemplary only, and are not intended to limit the scope of the application thereto. Various changes and modifications may be made therein by those of ordinary skill in the art without departing from the scope and spirit of the present application. All such changes and modifications are intended to be included within the scope of this application as claimed in the appended claims.

Those of ordinary skill in the art can realize that the units and algorithm steps of each example described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Skilled artisans may implement the described functionality using different methods for each particular application, but such implementations should not be considered beyond the scope of this application.

In the several embodiments provided in this application, it should be understood that the disclosed apparatus and method may be implemented in other manners. For example, the device embodiments described above are only illustrative. For example, the division of the units is only a logical function division. In actual implementation, there may be other division methods. For example, multiple units or components may be combined or May be integrated into another device, or some features may be omitted, or not implemented.

In the description provided herein, numerous specific details are set forth. It will be understood, however, that the embodiments of the present application may be practiced without these specific details. In some instances, well-known methods, structures and techniques have not been shown in detail in order not to obscure an understanding of this description.

Similarly, it is to be understood that in the description of the exemplary embodiments of the present application, various features of the present application are sometimes grouped together into a single embodiment, FIG. , or in its description. However, this method of application should not be construed as reflecting an intention that the claimed application requires more features than are expressly recited in each claim. Rather, as the corresponding claims reflect, the invention lies in the fact that the corresponding technical problem may be solved with less than all features of a single disclosed embodiment. Thus, the claims following the Detailed Description are hereby expressly incorporated into this Detailed Description, with each claim standing on its own as a separate embodiment of this application.

It will be understood by those skilled in the art that all features disclosed in this specification (including the accompanying claims, abstract and drawings) and any method or apparatus so disclosed may be used in any combination, except that the features are mutually exclusive. Processes or units are combined. Each feature disclosed in this specification (including accompanying claims, abstract and drawings) may be replaced by alternative features serving the same, equivalent or similar purpose, unless expressly stated otherwise.

Furthermore, those skilled in the art will appreciate that although some of the embodiments described herein include certain features, but not others, included in other embodiments, that combinations of features of different embodiments are intended to be within the scope of the present application within and form different embodiments. For example, in the claims, any of the claimed embodiments may be used in any combination.

Various component embodiments of the present application may be implemented in hardware, or in software modules running on one or more processors, or in a combination thereof. Those skilled in the art should understand that a microprocessor or a digital signal processor (DSP) may be used in practice to implement some or all functions of some modules according to the embodiments of the present application. The present application can also be implemented as a program of apparatus (eg, computer programs and computer program products) for performing part or all of the methods described herein. Such a program implementing the present application may be stored on a computer-readable medium, or may be in the form of one or more signals. Such signals may be downloaded from Internet sites, or provided on carrier signals, or in any other form.

It should be noted that the above-described embodiments illustrate rather than limit the application, and alternative embodiments may be devised by those skilled in the art without departing from the scope of the appended claims. In the claims, any reference signs placed between parentheses shall not be construed as limiting the claim. The application can be implemented by means of hardware comprising several different elements and by means of a suitably programmed computer. In a unit claim enumerating several means, several of these means may be embodied by one and the same item of hardware. The use of the words first, second, and third, etc. do not denote any order. These words can be interpreted as names.

The above are only specific embodiments of the present application or descriptions of the specific embodiments, and the protection scope of the present application is not limited thereto. Any changes or substitutions should be included within the protection scope of the present application. The protection scope of the present application shall be subject to the protection scope of the claims.

Claims

A semiconductor device, characterized in that the semiconductor device comprises:

an epitaxial layer, comprising a first surface and a second surface arranged oppositely;

a plurality of avalanche photodiodes are formed on the first surface of the epitaxial layer, and incident light is incident on the avalanche photodiodes from the second surface of the epitaxial layer;

A plurality of first electrodes are formed on the first surface of the epitaxial layer at intervals and completely cover the avalanche photodiodes corresponding to the upper and lower sides thereof;

The second electrode includes a heavily doped region formed on the second surface of the epitaxial layer.
The semiconductor device of claim 1, wherein the first electrode reflects incident light incident from the second surface of the epitaxial layer to the second surface of the epitaxial layer.
The semiconductor device according to claim 2, wherein the first electrode is a metal layer having a reflective surface.
The semiconductor device of claim 1, wherein the quantum efficiency of the avalanche photodiode is positively correlated with the thickness of the epitaxial layer.
The semiconductor device according to claim 1, wherein the thickness of the epitaxial layer is 20 μm-40 μm.
The semiconductor device according to claim 1, wherein the final doping concentration of the epitaxial layer is less than or equal to the initial doping concentration.
The semiconductor device according to claim 6, wherein the final doping concentration is less than or equal to 1×10 15 /cm 3 .
The semiconductor device of claim 1, wherein the semiconductor device comprises a first isolation structure, wherein the first isolation structure is disposed between adjacent avalanche photodiodes.
The semiconductor device according to claim 8, wherein the semiconductor device further comprises a second isolation structure, and the first isolation structure is disposed between the avalanche photodiode and the second isolation structure.
The semiconductor device according to claim 9, wherein the first isolation structure and the second isolation structure are doped regions with different doping types; and/or

The doping type of the first isolation structure is different from the doping type of the avalanche photodiode top contact layer.
9. The semiconductor device of claim 9, wherein the first electrode covers the second isolation structure.
The semiconductor device according to claim 1, wherein the heavily doped region has a depth of less than 1 μm; and/or

The heavily doped region has a doping concentration range greater than 5×10 18 /cm 3 and is formed by rapid annealing.
The semiconductor device according to claim 12, wherein the doping concentration of the heavily doped region ranges from 5×10 18 /cm 3 to 5×10 20 /cm 3 .
The semiconductor device of claim 1, wherein the heavily doped region is of the same doping type as the epitaxial layer.
The semiconductor device according to claim 1 or 14, wherein the epitaxial layer is P-type doped.
The semiconductor device according to claim 1, wherein the semiconductor device further comprises:

A light-transmitting bearing structure is provided on the second electrode and covers the second electrode.
The semiconductor device according to claim 16, wherein the carrier structure is a carrier wafer or a carrier glass.
A preparation method of a semiconductor device, characterized in that the preparation method comprises:

providing a substrate formed with an epitaxial layer, the epitaxial layer comprising a first surface and a second surface disposed oppositely, the first surface of the epitaxial layer being away from the substrate;

A plurality of avalanche photodiodes are formed on the first surface of the epitaxial layer, wherein the incident light of the avalanche photodiodes is incident from the second surface of the epitaxial layer;

forming a heavily doped region on the second surface of the epitaxial layer to serve as a second electrode;

A plurality of first electrodes isolated from each other are formed on the first surface of the epitaxial layer to respectively cover the avalanche photodiodes below.
The manufacturing method according to claim 18, wherein the first electrode is used for reflecting light incident from the second surface of the epitaxial layer to the second surface of the epitaxial layer.
The preparation method according to claim 19, wherein the first electrode is a metal layer having a reflective surface.
The preparation method according to claim 18, wherein the quantum efficiency of the avalanche photodiode is positively correlated with the thickness of the epitaxial layer.
The preparation method according to claim 18, wherein the final doping concentration of the epitaxial layer is less than or equal to the initial doping concentration.
The preparation method according to claim 22, wherein the final doping concentration is less than or equal to 1×10 15 /cm 3 .
The manufacturing method according to claim 18, wherein a first isolation structure is formed by ion implantation, and the first isolation structure is disposed between the adjacent avalanche photodiodes.
The manufacturing method according to claim 24, wherein a second isolation structure is formed by ion implantation, and the first isolation structure is disposed between the avalanche photodiode and the second isolation structure.
The preparation method according to claim 25, wherein the first isolation structure and the second isolation structure have different types of ions implanted; and/or

The type of ions implanted by the first isolation structure is different from the type of ions doped in the top contact layer of the avalanche photodiode.
The manufacturing method according to claim 25, wherein the first electrode covers the second isolation structure.
The preparation method according to claim 18, wherein the forming a heavily doped region on the second surface of the epitaxial layer to serve as the second electrode comprises:

thinning the epitaxial layer, so that the thickness from the second surface of the epitaxial layer to the first surface after thinning is a target thickness;

A heavily doped region is formed on the second surface of the thinned epitaxial layer to serve as a second electrode.
The preparation method according to claim 28, wherein the initial thickness of the epitaxial layer is greater than 50 μm, and the thickness from the second surface of the epitaxial layer to the first surface after thinning is 20 μm-40 μm.
The preparation method according to claim 28, wherein the thinning of the epitaxial layer comprises:

The substrate and a portion of the epitaxial layer are removed.
The manufacturing method according to claim 30, wherein the top of the removed part of the epitaxial layer includes a region where impurities in the substrate are diffused.
The preparation method according to claim 28, wherein the thinning of the epitaxial layer is such that the thickness from the second surface to the first surface of the epitaxial layer after the thinning is a target thickness ,include:

Bonding a carrier wafer on the first surface of the epitaxial layer to cover the first surface;

thinning the epitaxial layer, so that the thickness from the second surface of the epitaxial layer after the thinning to the first surface is a target thickness;

The carrier wafer is removed after forming the second electrode.
The preparation method according to claim 18, wherein the forming a heavily doped region on the second surface of the epitaxial layer to serve as the second electrode comprises:

Ion implantation is performed on the second surface of the epitaxial layer to form a heavily doped region as the second electrode.
The preparation method according to claim 33, wherein the energy of ion implantation on the second surface of the epitaxial layer is 5Kev-50Kev; and/or

the depth of the ion implantation is less than 1 μm; and/or

The concentration range of the ion implantation is greater than 5×10 18 /cm 3 .
The preparation method according to claim 34, wherein the concentration range of the ion implantation is 5×10 18 /cm 3 to 5×10 20 /cm 3 .
The preparation method according to claim 33, wherein after the ion implantation, the method further comprises the step of performing rapid annealing to prevent impurity diffusion.
The preparation method according to claim 36, wherein the temperature of the rapid annealing is 800°C-1600°C; and/or

The rapid annealing time is 10s-300s.
The preparation method according to claim 18, wherein the heavily doped region is of the same doping type as the epitaxial layer.
The preparation method according to claim 18 or 37, wherein the epitaxial layer is P-type doped.
The preparation method according to claim 18, characterized in that, after forming the second electrode and before forming the first electrode, the method further comprises:

A light-transmitting bearing structure is bonded on the second electrode to cover the second electrode.
The preparation method according to claim 40, wherein the bearing structure is a bearing wafer or a bearing glass.
A receiving chip, characterized in that the receiving chip comprises:

The semiconductor device according to any one of claims 1 to 17, for receiving the light pulse sequence reflected by the detected object, and converting the received light pulse sequence into a current signal;

The signal processing unit is used for receiving and processing the current signal of the avalanche photodiode to output a time signal.
A distance measuring device, characterized in that the distance measuring device comprises:

Light emitting circuit for emitting light pulse sequence;

The receiving chip according to claim 42, which is used for receiving the optical pulse sequence reflected by the detected object, and outputting a time signal based on the received optical pulse sequence;

an arithmetic circuit for calculating the distance between the detected object and the distance measuring device according to the time signal.
A movable platform, characterized in that the movable platform comprises:

Movable platform body;

The distance-measuring device of claim 43, wherein the distance-measuring device is provided on the movable platform body;

A power system is used to drive the movable platform body to move.
The movable platform of claim 44, wherein the movable platform comprises a drone, an autonomous vehicle, or a robot.