JP2010522426A - Method for manufacturing hybrid substrate - Google Patents

Abstract

The present invention relates to a method of manufacturing a hybrid substrate comprising at least two crystalline material layers that are directly bonded to each other. The method includes injecting at least one atomic species and / or ionic species into a donor substrate to form a fragile zone that forms an interface between the active layer and its remainder, and a donor substrate and a receiver substrate The surface is subjected to a heat treatment at 900 ° C. to 1200 ° C. for at least 30 seconds under an atmosphere of hydrogen and / or argon, the surfaces are bonded to each other, and the remaining portion is separated, The nature of the species, implantation dose and implantation energy allow defects induced in the donor substrate by these species to subsequently isolate the remainder of the donor substrate, but during the heat treatment, It is selected so that it does not develop enough to prevent bonding or to deform the surface of the donor substrate.
[Selection] Figure 6

Description

  The present invention relates to a method for manufacturing a hybrid substrate comprising at least two crystalline material layers bonded together by direct bonding.

  This type of substrate can be used in the field of optics, electronics or optoelectronics, and these terms generally include microelectronics, nanoelectronics, opto-nanoelectronics and component technology.

  The properties of the two material layers may be the same or different, and the term “property” refers to the chemical properties of the materials, the physicochemical properties of the materials and / or the crystal orientation of the materials. Range.

  The term “direct bond” of two layers or two substrates means a molecular bond without an intermediate layer such as an adhesive layer.

  Hybrid substrates include those well known to those skilled in the art under the acronym DSB (direct silicon bonding). Such a substrate comprises a silicon active layer directly bonded to a receiver substrate formed of silicon of different crystal orientation without forming an intermediate layer, in particular without forming a buried oxide layer. Thus, it is possible to produce a substrate comprising a silicon layer having a (110) crystal orientation that is directly bonded to a silicon support having a (100) crystal orientation, or vice versa.

  If the receiver substrate is made of silicon carbide (SiC), it is possible to make a hybrid substrate known to those skilled in the art with the acronym SopSiC (silicon-on-polycrystalline SiC).

  Such hybrid substrates are useful for the production of high performance microelectronic circuits.

  C. Y. Sung's paper "Direct Silicon Bonded (DSB) Mixed Orientation Substrate for High Y er and M e n e s e n s e n t e n e n e n e n e n e n e n e n e n e n e n e n e n e n e n e n e n e n e n e n e n e n e n e n e n e n e n e n e n e n e n e n e n e n e n e n e n e n e n e n e n e n e n e n e n e n e n e n i 160-161 gives examples of making such a substrate, which is an example of transferring a layer of a (110) silicon donor substrate onto a (100) silicon receiver substrate by subsequent thinning bonding. It is. This paper states that no such insulating layer is required between two layers that are bonded together in the fabrication of such a substrate.

The above article also be SiO ₂ insulating layer is not present in the final structure, it mentions that means that preferably more preparation prior to bonding of the hydrophobic type than hydrophilic.

  The reason for this is that hydrophilic bonding involves the formation of a thin silicon oxide layer between the surface preparations of the layers that are to be brought into close contact with each other, and this oxide layer embedded in the final structure is, for example, very hot. This is because the final annealing step must then be removed, which complicates the manufacturing method in this case.

  However, hydrophobic bonds with hydrogen-terminated bonds are much more difficult to implement because these hydrogen-terminated bonds attract particles that adversely affect the bond.

  A method for obtaining a thin layer of semiconductor material from a donor substrate is also known from US Pat. No. 6,020,252. In this method, a rare gas or hydrogen ions are injected into a donor substrate at a predetermined temperature and a predetermined implantation dose to form a fragile zone therein, and then the substrate is divided into two on both sides of the fragile surface. The heat treatment is performed at a high temperature sufficient to separate the parts.

  According to the content described in the above document, a sufficient amount of microcavities to form a fragile zone is formed in the substrate, however, it is insufficient to realize separation only by the subsequent heat treatment. The temperature and the implantation dose are selected so as to be a quantity. Separation requires an additional mechanical force.

  However, this document is not clearly related to surface preparation that allows for excellent direct bonding.

  The object of the present invention is to solve the above-mentioned drawbacks of the prior art, in particular, it does not require a bond using an intermediate layer, and the bond between the donor substrate and the receiver substrate is made with a high quality hydrophobic bond, It is to provide a method for producing a hybrid substrate obtained by layer transfer.

  For this purpose, the present invention is provided by a crystalline substrate, referred to as a “donor” substrate, comprising at least two crystalline layers that are directly bonded to each other, including a material layer referred to as an “active” layer. The present invention relates to a method for manufacturing a hybrid substrate including a material layer.

According to the present invention, the method comprises the following sequential steps:
Injecting at least one atomic species and / or ionic species into the donor substrate to form a fragile zone forming an interface between the active layer of the donor substrate and the remainder thereof;
One of the surfaces of the donor substrate, referred to as the “front” surface, and one of the surfaces of the crystalline substrate, referred to as the “receiver” substrate, referred to as the “front” surface, Applying a heat treatment referred to as a “preparation before bonding” heat treatment at a temperature of 800 ° C. to 1200 ° C. for at least 30 seconds in a gas phase atmosphere containing hydrogen and / or argon to hydrophobize the surface;
Directly bonding the surfaces together;
Performing a heat treatment of the two substrates under conditions to obtain a strong bond between the two substrates;
Separating the remainder along the zone of weakness by purely mechanical action,
The nature of the atomic species and / or ionic species, implantation dose and implantation energy allows defects induced in the donor substrate by these species to subsequently isolate the remainder of the donor substrate, During the pre-bonding heat treatment, it is selected to prevent subsequent bonding or to grow to such an extent that the donor substrate surface is deformed.

According to other advantageous and non-limiting features of the invention, the following may be incorporated individually or in combination:
The pre-bonding preparation process is performed in a gas phase atmosphere containing only argon.
The pre-bonding preparation process is performed in a gas phase atmosphere containing only hydrogen.
-The pre-bonding preparation process is performed in a rapid heating annealing (RTP) furnace.
The heat treatment for strengthening the bonding between the two substrates is performed by a long heat treatment at a temperature of 1100 ° C. or higher for at least 2 hours.
The species injected to form the fragile zone is selected from hydrogen, helium, fluorine, neon, argon, krypton and xenon.
The active layer of the donor substrate is selected from silicon (Si), (110) silicon, (100) silicon, silicon-germanium (SiGe), germanium (Ge), silicon carbide (SiC) and gallium nitride (GaN) Consists of materials.
The receiver substrate is composed at least in part of a material selected from silicon (Si), (110) silicon, (100) silicon and silicon carbide (SiC);

  Other features and advantages of the present invention will become apparent from the following description of the invention which refers to the accompanying drawings. The accompanying drawings are not meant to be limiting, but are intended to illustrate one possible embodiment of the invention.

It is a figure which shows the continuous step in the manufacturing method by this invention. It is a figure which shows the continuous step in the manufacturing method by this invention. It is a figure which shows the continuous step in the manufacturing method by this invention. It is a figure which shows the continuous step in the manufacturing method by this invention. It is a figure which shows the continuous step in the manufacturing method by this invention. It is a figure which shows the continuous step in the manufacturing method by this invention.

  The sequence of the various steps of the method will now be briefly described.

  As can be seen in FIG. 1, the “donor” substrate 1 comprises two opposing surfaces 10, 11 referred to as the “front” and “back” surfaces, respectively.

  As shown in FIG. 2, the donor substrate 1 can then be implanted with atomic or ionic species such that a fragile zone 12 is formed therein, which is referred to as an “active” layer 13. Forming a boundary between the layer 13 and the remainder 14 of the substrate.

This implantation is preferably performed via a sacrificial insulating layer 3, for example a silicon dioxide (SiO ₂ ) layer, deposited on the surface 10 of the substrate 1.

  This insulating layer 3 is then removed as shown in FIG.

  The donor substrate 1 and the “receiver” substrate 2 are subsequently subjected to a “preparation before bonding” process, which will be described in detail later (see FIG. 4).

  The “receiver” substrate 2 comprises two opposing surfaces 20, 21 called “front” surface and “back” surface, respectively.

  Next, the surface 20 of the receiver substrate 2 is attached to the surface 10 of the donor substrate 1 by direct bonding (see FIG. 5).

  Reference numeral 4 is attached to the bonding interface.

  After the treatment for strengthening the bond, the remaining part 14 of the donor substrate 1 is separated as shown in FIG. 6, the active layer 13 is transferred onto the receiver substrate 2 and the hybrid designated by reference numeral 5 A substrate is obtained.

  These various steps will now be described in more detail.

  The donor substrate 1 and the receiver substrate 2 may or may not be made of a semiconductor material.

  In general, the material constituting the donor substrate 1 is selected from crystalline materials that can form cavities with a high concentration distribution therein by an implantation process of atomic species and / or ion species, followed by a thermal annealing process. Is done.

  As an example, the material constituting the donor substrate 1 is made of silicon (Si), (110) silicon, (100) silicon, silicon germanium (SiGe), germanium (Ge), silicon carbide (SiC), and silicon nitride (GaN). It may be selected.

  The receiver substrate 2 is composed of any crystalline or non-crystalline material, such as silicon (Si), (110) silicon, (100) silicon or silicon carbide (SiC), preferably single crystal silicon or polycrystalline. Although silicon carbide, it may be polycrystalline silicon. It may be a semiconductor or insulator material.

  As two particular applications of the present invention, the donor substrate 1 and the receiver substrate 2 are made of silicon, preferably single crystal silicon, and have different crystal orientations (eg (100), (110) or (111)). There is an application for forming a mold substrate, or an application for forming a SopSiC type substrate in which the donor substrate 1 is made of silicon (preferably monocrystalline silicon) and the receiver substrate 2 is made of polycrystalline silicon carbide.

  Note that the donor and receiver substrates may be multilayer substrates. However, in this case, it is necessary that the materials of the layers constituting the surfaces 10 and 20 of the substrates 1 and 2 meet the above specifications.

  The step of implanting atomic species and / or ionic species is the step of implanting seeds, their doses and their implantation energy, and defects induced in the donor substrate 1 by these species after which the remainder 14 is separated. (See FIG. 6), but during the pre-bonding heat treatment shown in FIG. 4, the surface 10 to be bonded is deformed or the subsequent bonding shown in FIG. 5 is prevented. It is performed by choosing not to grow.

  Examples of species that can be implanted can be hydrogen (H), helium (He), fluorine (F), neon (Ne), argon (Ar), krypton (Kr) and xenon (Xe). .

  These species are particularly suitable for implantation into the silicon substrate 1.

  The selection of these species, their doses and their implantation energy is done to avoid the phenomenon of surface bubbling that normally occurs when the implanted material is annealed in a standard manner.

In general, it is also possible to perform co-implantation, where different species successively strike the surface of the substrate. For example, it is preferable to use helium implantation first, followed by H ⁺ ion implantation.

  Similarly, the nature of these species, their dose, and their implantation energy are selected to limit the foaming of the implanted species.

Therefore, whether single injection or simultaneous injection, the implantation energy of the species is selected between 20 keV and 500 keV, and the dose of the species is 1 × 10 ¹⁴ at / cm ² to 1 × 10 ¹⁷ at / Selected between cm ² .

As an example, helium atoms are implanted into the substrate with an energy of about 30-200 keV and a dose in the range of 5 × 10 ¹⁶ to 1 × 10 ¹⁷ at / cm ² . In the case of argon atoms, the applied energy is about 200 to 500 keV, and the implantation dose is 1 × 10 ^{16 to} 5 × 10 ¹⁶ at / cm ² .

  In the case of co-injection, for example, hydrogen co-injected with fluorine or hydrogen co-injected with helium can be used.

In the case of hydrogen / fluorine co-implantation, hydrogen is implanted with an energy of 20-50 keV and a dose of 1 × 10 ^{15 to} 5 × 10 ¹⁶ H ⁺ / cm ² , while fluorine has an energy of 150-200 keV, 1 Implantation is performed at an implantation dose amount of × 10 ¹⁴ to 1 × 10 ¹⁶ F ⁺ / cm ² .

In the case of hydrogen / helium co-implantation, helium is implanted with an energy of 70-90 keV and a dose of 1 × 10 ^{16 to} 6 × 10 ¹⁶ He ⁺ / cm ² , while hydrogen is implanted with an energy of 70-90 keV, 1 Implantation is performed with an implantation dose amount of × 10 ^{15 to} 6 × 10 ¹⁵ H ⁺ / cm ² .

  Regarding injection, the reader can refer to the literature on the Smart Cut ™ process.

  Preferably, the implantation is performed through the surface 10 as shown in FIG.

Also preferably, all of these implantations are performed through the sacrificial oxide layer 3. This oxide layer 3 can be formed thermally (for example, SiO _{2 in} the case of a silicon substrate), or chemical vapor deposition (CVD) at atmospheric pressure or low pressure chemical vapor deposition (LPCVD). Such a deposition technique well known to those skilled in the art can be used. Here, these techniques will not be described in detail.

  The oxide layer 3 may be a natural oxide.

  Thereafter, the sacrificial oxide layer 3 is removed after the implantation, for example by immersing the substrate 1 in a diluted hydrofluoric acid (HF) solution or placing the substrate 1 in an atmosphere of hydrofluoric acid vapor. To be removed.

  After removing the sacrificial oxide layer, an RCA type cleaning operation is preferably performed to protect the surface 10 from contaminating particles.

The treatment using a chemical bath called RCA cleaning (RCA-clean) means that the surface 10 is
A first bath of a solution known as SC1 (Standard Clean 1) containing a mixture of ammonium hydroxide (NH ₄ OH), hydrogen peroxide (H ₂ O ₂ ) and deionized water, and hydrochloric acid (HCl) Treatment in a second bath of a solution known as SC2 (Standard Clean 2) containing a mixture of water, hydrogen peroxide (H ₂ O ₂ ) and deionized water.

  The pre-bonding preparation process shown in FIG. 4 is a temperature of 800 ° C. to 1200 ° C. in a gas phase atmosphere containing hydrogen and / or argon but not oxygen on at least one of the surfaces 10 and 20 to be bonded. Heat treatment.

  Thus, the gas phase atmosphere is selected to include hydrogen alone, argon alone, or a mixture of these two gases, or hydrogen, argon, or a mixture of these two gases in combination with another gas other than oxygen. Is done.

  The duration of this process is at least 30 seconds, but preferably does not exceed a few minutes.

  The action of hydrogen and / or argon removes any native oxide present on the treated surface, passivates these surfaces with hydrogen atoms, and extremely reduces the surface roughness. It is to be.

  This pre-bonding pretreatment also has the effect of hydrophobizing the treated surface. This effect was demonstrated by measuring the water contact angle and obtaining a value of 80 °. This value is much greater than the value obtained after processing of the “HF-last” type, typically 70 ° (see the paper by Y. Becklund, Karin Hermasson and L. Smith, “Bond-strength measurements related to silicon surface hydrophility ", J. Electrochem. Soc, Vol. 1398, No. 8, 1992).

  The advantage of this treatment is that no species are adsorbed on the treated surface. When desorbed, the hydrogen atoms are very small and a covalent bond can be formed between the opposing surfaces 10 and 20, so that the trapped state at the interface is not maintained and diffuses into the material, causing degassing defects. Does not occur.

  In addition, this process is dry, unlike the example of the HF-last process. For example, this process is simpler to implement because it does not require drying.

Finally, this pre-bonding preparation process has the effect of trapping implanted ions, for example He ⁺ ions, and stabilizing them in the resulting microcavity. As a result, the microcavities merge and the injected material in the zone containing the microcavities becomes brittle. However, the injection conditions are selected so that the layer 13 is not separated from the remaining portion 14 due to the coalescence phenomenon.

  This pre-bonding preparation can be performed in a controlled atmosphere, for example, in a high temperature annealing chamber in a single wafer RTP (rapid heat treatment) furnace or an epitaxial growth furnace.

  The use of a conventional furnace for batch processing of substrates may be envisaged.

  After the treatment, the surfaces 10, 20 must be bonded very quickly so as to minimize the risk of contamination due to ambient atmospheric pressure. This coupling step is shown in FIG.

  It is also possible to store the processed substrate in a chamber having a controlled atmosphere, preferably containing only inert gases, typically argon or nitrogen. By such processing, it is possible to extend the hold time, that is, the time until the donor substrate 1 and the receiver substrate 2 are bonded to each other.

  It was also found that the surface that had undergone the pre-bonding preparation was much less reactive than the surface prepared by the HF-last process. This reduces contamination by particles on these surfaces. Therefore, industrialization becomes easy.

  The direct bonding step shown in FIG. 5 corresponds to bonding the surfaces 10 and 20 of the donor substrate 1 and the receiver substrate 2 to each other, that is, bonding by molecular adhesion.

  After this bonding step, the treatment for strengthening the bonding is carried out in the form of a long heat treatment, ie at a temperature of 1100 ° C. or higher for at least 2 hours.

  As shown in FIG. 6, the donor substrate 1 is then separated from the remaining portion 14.

  This separation is purely mechanical.

  "Pure" mechanical separation is by mechanical action, for example by running a tool such as a blade along the weak zone 12 from one side of the substrate, or applying an air jet or water jet to this point Begins with.

  During this type of purely mechanical separation, the structure may be rotated to facilitate separation.

  In the following, two examples relating to the procedure for carrying out the present invention are given.

A (110) Si silicon substrate covered with a silicon oxide (SiO ₂ ) layer was subjected to helium ion (He ⁺ ) implantation with a dose slightly lower than 1 × 10 ¹⁷ He ⁺ / cm ² and an implantation energy of 50 keV. .

Thereafter, the formed silicon oxide SiO ₂ was removed by treatment in a hydrofluoric acid (HF) solution, and then the RCA-clean type cleaning was performed.

  Thereafter, this silicon donor substrate and a receiver substrate made of silicon but also of (100) crystal orientation are bonded to each other in a gas phase atmosphere containing hydrogen and argon at a temperature of 1050 ° C. for approximately 4 minutes. Preparation processing was performed.

  Thereafter, these two substrates 1 and 2 were bonded to each other on their respective surfaces, and heat treatment was performed at 1100 ° C. for 2 hours in order to strengthen the bonding.

  Finally, the donor substrate was separated from the remainder by purely mechanically inserting the blade.

  In this way, a silicon / silicon DSB type substrate could be obtained.

  This product therefore had the very high quality bonding interface necessary for future component manufacturing.

Hydrogen / fluorine co-implantation was performed on a (100) Si silicon substrate covered with a silicon oxide (SiO ₂ ) layer. Fluorine was implanted with a dose of 1 × 10 ¹⁵ Fe ⁺ / cm ² and an implantation energy of 180 keV, while hydrogen was implanted with a dose of 4 × 10 ¹⁶ H ⁺ / cm ² and an implantation energy of 30 keV.

Thereafter, the formed silicon oxide SiO ₂ was removed by treatment in a hydrofluoric acid (HF) solution, and then the RCA-clean type cleaning was performed.

  Thereafter, a pre-bonding preparation process was performed for about 5 minutes at a temperature of 800 ° C. in a gas-phase atmosphere containing hydrogen on the silicon donor substrate and the receiver substrate made of polycrystalline silicon carbide (pSiC).

  These two substrates 1 and 2 were bonded to each other on their respective surfaces, and heat treatment was performed at 1000 ° C. for 3 hours in order to strengthen the bonding.

  Finally, the donor substrate was separated from the remainder by purely mechanically injecting a fluid jet.

  In this way, a SopSiC (silicon on polycrystalline silicon carbide) type substrate having a very high quality bonding interface could be obtained.

Claims (8)

In a method of manufacturing a hybrid substrate provided by a crystalline substrate referred to as a “donor” substrate, comprising a material layer referred to as an “active” layer and comprising at least two crystalline material layers bonded directly to each other And at least one atomic species and / or ion species is implanted into the donor substrate to form an interface between the active layer of the donor substrate and the remainder thereof. Performing a step of forming a fragile zone (12);
One of the surfaces of the donor substrate, referred to as the “front” surface, and one of the surfaces of the crystalline substrate, referred to as the “receiver” substrate, referred to as the “front” surface. Applying a heat treatment referred to as “preparation before bonding” heat treatment to hydrophobize the surface at a temperature of 800 ° C. to 1200 ° C. for at least 30 seconds in a gas phase atmosphere containing hydrogen and / or argon;
Directly bonding the surfaces to each other;
Performing a heat treatment of the two substrates under conditions for obtaining a strong bond between the two substrates;
Separating the remainder along the fragile zone by purely mechanical action,
The nature of the atomic species and / or ionic species, implantation dose, and implantation energy allow defects induced in the donor substrate by these species to subsequently isolate the remainder of the donor substrate. However, the method for manufacturing a hybrid substrate is selected so as to prevent the subsequent bonding or to grow to such a degree that the surface of the donor substrate is deformed during the heat treatment for preparation before the bonding.   The method for manufacturing a hybrid substrate according to claim 1, wherein the pre-bonding preparation process is performed in a gas phase atmosphere containing only argon.   The method for manufacturing a hybrid substrate according to claim 1, wherein the pre-bonding preparation process is performed in a gas phase atmosphere containing only hydrogen.   The method for manufacturing a hybrid substrate according to claim 1, wherein the pre-bonding preparation process is performed in a rapid heating annealing (RTP) furnace.   The manufacturing of a hybrid substrate according to any one of claims 1 to 4, wherein the heat treatment for strengthening the bonding of the two substrates is performed by a long-time heat treatment at a temperature of 1100 ° C or higher for at least 2 hours. Method.   The hybrid substrate manufacture according to any one of claims 1 to 5, wherein the species injected to form the fragile zone is selected from hydrogen, helium, fluorine, neon, argon, krypton and xenon. Method.   The active layer of the donor substrate is composed of a material selected from silicon, (110) silicon, (100) silicon, silicon-germanium, germanium, silicon carbide and gallium nitride. A method for manufacturing a hybrid substrate according to claim 1.   The hybrid substrate according to any one of claims 1 to 7, wherein the receiver substrate is at least partially composed of a material selected from silicon, (110) silicon, (100) silicon, and silicon carbide. Manufacturing method.

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