DE102014102037A1 - A semiconductor device and method for applying a coating to a plurality of semiconductor devices - Google Patents

Abstract

A semiconductor device (10) is described, comprising a semiconductor body (3) having a first contact layer (1) on a first main surface (11) and a second contact layer (2) on a second main surface (12). The semiconductor body (3) has on the first main surface (11) a depression (4) which has a distance from two opposite side surfaces (5, 6) of the semiconductor body (3), the first contact layer (1) being completely in the recess (4) is arranged. The second contact layer (2) has from the opposite side surfaces (5, 6) at an equal or greater distance than the recess (4). Furthermore, a method for applying a coating (7, 8) to a plurality of semiconductor devices (10a, 10b) is described.

Description

The invention relates to a semiconductor device, in particular an optoelectronic component such as a semiconductor laser, and a method for applying a coating to a plurality of semiconductor devices.

Semiconductor devices, in particular optoelectronic components such as semiconductor lasers or LEDs, typically have a semiconductor body which is provided for electrical contacting with electrical contact layers. By way of example, the semiconductor body may have an n-side contact layer on a first main area and a p-side contact layer on an opposite second main area. Often, the side surfaces of the semiconductor body, which are perpendicular to the main surfaces, provided with a functional coating. For example, the side surfaces of an optoelectronic component are provided with a reflection-reducing or a reflection-enhancing coating.

For applying a coating on the side surfaces of the semiconductor body, the semiconductor devices can be stacked on top of each other and thus form a so-called coating horde. In this way, it is possible to coat the side surfaces of a plurality of semiconductor bodies simultaneously. In this procedure, however, the problem may arise that the contact surfaces of semiconductor bodies adjacent to the main surfaces of the semiconductor bodies contact one another. This may lead to an adhesion of the contact layers due to the high process temperatures during the coating process and / or due to the applied coating material, so that it is difficult to separate the semiconductor bodies from each other after the coating process. In order to prevent contact of the contact layers of adjacent semiconductor bodies in the stack of semiconductor bodies in the coating process, spacers may be inserted between the semiconductor devices, which in the case of stacked laser bars are referred to as dummy bars.

By inserting the spacers but with a predetermined size of the layer stack fewer semiconductor devices can be coated simultaneously. Furthermore, the insertion of the spacers increases the manufacturing outlay and there is the risk that impurities are introduced into the stack of semiconductor bodies.

The invention has for its object to provide an improved semiconductor device whose side surfaces can be coated in a particularly economical manner. Furthermore, a method for applying a coating to a plurality of semiconductor devices is to be specified.

These objects are achieved by a semiconductor device and a method according to the independent claims. Advantageous embodiments and modifications of the invention are the subject of the dependent claims.

The semiconductor device has, according to at least one embodiment, a semiconductor body which has a first main area and a second main area opposite the first main area. In particular, the semiconductor body may have a semiconductor layer sequence applied to a substrate, the first main area being a rear side of the substrate remote from the semiconductor layer sequence and the second main area being a surface of the semiconductor layer sequence opposite the substrate. In other words, the semiconductor body is bounded in a vertical direction by the first main surface and the opposite second main surface. In the lateral direction, the semiconductor body is bounded by side surfaces, which are preferably perpendicular to the main surfaces.

The semiconductor device further has a first contact layer on the first main surface of the semiconductor body and a second contact layer on the second main surface of the semiconductor body. The first contact layer and the second contact layer are used for electrically contacting the semiconductor body, which may be, for example, an optoelectronic component. The semiconductor body may have, for example, an n-doped semiconductor region and a p-doped semiconductor region, wherein the first contact layer contacts the n-doped semiconductor region and the second contact layer contacts the p-doped semiconductor region. The first contact layer and the second contact layer may in particular comprise a metal or a metal alloy. Alternatively, it is possible that the first contact layer and / or the second contact layer comprise a non-metallic electrically conductive material, for. B. a transparent conductive oxide (TCO) such as ITO.

In the semiconductor device, the semiconductor body advantageously has a recess on the first main surface, which has in each case a spacing from two opposite side surfaces of the semiconductor body. In other words, the depression does not immediately adjoin any of the opposing side surfaces, so that in each case an edge region of the semiconductor body is arranged between the depression and the side surfaces of the semiconductor body.

In the semiconductor device, the first contact layer is advantageously arranged completely in the depression. The first contact layer therefore, like the depression, does not adjoin the side surfaces of the semiconductor body, but is spaced from the side surfaces by the edge regions of the semiconductor body which are arranged between the depression and the side surfaces.

In the semiconductor device, the second contact layer arranged on the second main surface advantageously has a distance from the opposing side surfaces of the semiconductor body which is greater than or equal to the distance of the depression from the side surfaces. Thus, the second contact layer does not directly adjoin the side surfaces of the semiconductor body, but, like the first contact layer, is also spaced from the side surfaces by edge regions of the semiconductor body.

Several similar examples of the semiconductor device described herein may be advantageously stacked on each other such that the first main surface of a semiconductor device and the second main surface of an adjacent semiconductor device face each other without the first contact layer of the semiconductor device and the second contact layer of the semiconductor device adjacent to each other in the stack touch. This is achieved in particular in that the first contact layer of the semiconductor device is arranged in a depression of the semiconductor body. In this way, it is advantageously prevented that the first and second contact layers of adjacent semiconductor devices adhere to one another when coating the front sides and / or rear sides by applied coating material.

In a preferred embodiment, a vertical projection of the second contact layer on the first main surface of the semiconductor body is completely within the recess. Under a vertical projection is here to understand a projection perpendicular to the main surfaces of the semiconductor body. In other words, the second contact layer has the same or a smaller lateral extent than the depression.

Furthermore, the depression preferably has a depth that is greater than the sum of a thickness of the first contact layer and a thickness of the second contact layer.

Because the lateral extent of the second contact layer is less than the lateral extent of the depression and the depression has a depth which is greater than the sum of the thicknesses of the first and the second contact layer, the depression can advantageously be the first contact layer as well as the first contact layer completely absorb the second contact layer. This has the particular advantage that the semiconductor device can be mounted on the first main area on the second main area of a similar semiconductor device, wherein the recess of the semiconductor device and the second main area of the further semiconductor device form a cavity that covers both the first contact layer of the semiconductor device and the semiconductor device second contact layer of the further semiconductor device encloses.

When applying coating material to the front sides and / or rear sides of the stacked semiconductor devices, the first contact layer of the semiconductor device and the second contact layer of the adjacent semiconductor device advantageously do not touch each other, so that they could not stick together by a high process temperature possibly occurring during the coating process.

In a preferred embodiment, a front side and / or a rear side of the semiconductor device has a coating, wherein the front side and the rear side are preferably perpendicular to the first and second main surface and to the side surfaces. The coating may in particular be a reflection-reducing or a reflection-enhancing coating. The coating may, for example, be a dielectric mirror, which is preferably formed from a plurality of dielectric layers. Alternatively, the coating may also be a reflection-reducing coating, which is preferably formed from a plurality of dielectric layers. The materials and the thicknesses of the dielectric layers are in these cases selected such that a reflection-increasing or reflection-reducing effect is achieved for a desired wavelength, for example for the wavelength of a radiation emitted by a semiconductor laser. The dielectric layers may comprise, for example, oxides, nitrides or fluorides. Furthermore, it is also possible that the coating has one or more metal layers.

The semiconductor device according to a preferred embodiment is an optoelectronic component, such as an LED, a photodetector or a semiconductor laser.

In particular, the semiconductor device may be a semiconductor laser, e.g. As a laser bar, be, wherein the front side and the back of the semiconductor body form resonator mirror of the semiconductor laser. In this case, advantageously, the rear side of the semiconductor body has a reflection-enhancing coating, which forms the first resonator mirror of the semiconductor laser. A opposite front side of the semiconductor body may be provided as a radiation output surface of the semiconductor laser and forms the second resonator mirror of the semiconductor laser. The front side provided as a decoupling surface can have a reflection-enhancing coating with a lower reflectivity than a coating on the opposite rear side or a reflection-reducing coating.

The semiconductor body preferably has a semiconductor layer sequence applied to a substrate. The semiconductor layer sequence may in particular have an active layer suitable for the emission of radiation.

By way of example, the semiconductor layer sequence has an n-type semiconductor region, a p-type semiconductor region and an active layer arranged therebetween. Preferably, the n-type semiconductor region faces the substrate and the p-type semiconductor region faces the second main surface of the semiconductor body. The first main surface of the semiconductor body, on which the depression is formed in the semiconductor body, may in particular be a surface of the substrate facing away from the semiconductor layer sequence. The substrate is in particular a semiconductor substrate, preferably an n-type semiconductor substrate.

According to a preferred embodiment, the depression has a spacing of at least 50 μm, preferably between 50 μm and 200 μm inclusive, from the side surfaces of the semiconductor body. In other words, the edge regions of the semiconductor body, which delimit the depression laterally, each have a width of at least 50 μm, preferably between 50 μm inclusive and 200 μm inclusive. When stacking a plurality of semiconductor devices, only the edge regions of the semiconductor body are located on the first main surface on the second main surface of the adjacent semiconductor body.

According to at least one embodiment of the method of applying a coating to a plurality of semiconductor devices, the semiconductor devices are stacked such that the first main surface of a semiconductor device and the second main surface of an adjacent semiconductor device face each other, wherein the recess in the semiconductor body of the semiconductor device and the second main surface of the semiconductor device adjacent semiconductor device include the first contact layer of the semiconductor device and the second contact layer of the adjacent semiconductor device.

A coating is subsequently applied to the front sides and / or back sides of the semiconductor devices stacked in this way. In the method, the coating is advantageously applied simultaneously to the adjoining front sides and / or rear sides of adjacent semiconductor devices, wherein due to the inclusion of the facing contact layers in the cavity there is no risk that the contact layers by applied coating material and / or an increased process temperature in the Adhere coating process to each other. The semiconductor devices arranged in the stack can therefore be separated again without difficulty after the coating process.

In particular, it is advantageously not necessary in the method to insert spacers between the adjacent semiconductor devices in order to prevent sticking of the adjacent contact layers. Since spacers are not needed, a stack of semiconductor devices can have about twice as many semiconductor devices as an equally sized stack of spacers between adjacent semiconductor devices. The absence of spacers between the semiconductor devices also eliminates the risk of introducing contaminants through the spacers. With the method, the semiconductor devices can therefore be particularly efficient, inexpensive and reliable coated.

Further advantageous embodiments of the method will become apparent from the previous description of the semiconductor device and vice versa.

The invention will be described below with reference to embodiments in connection with 1 and 2 explained in more detail.

Show it:

1A FIG. 2 a schematic representation of a plan view of a semiconductor device according to an embodiment, FIG.

1B a schematic representation of a cross section along the line AB of the semiconductor device according to the embodiment,

2A FIG. 2 is a schematic representation of a plan view of a stack of four semiconductor devices in an intermediate step of the method according to an exemplary embodiment, FIG.

2 B a schematic representation of a cross section along the line CD through the stack of four semiconductor devices in the Intermediate step of the method according to the embodiment,

2C a schematic representation of a plan view of the stack of four semiconductor devices in a further intermediate step of the method according to the embodiment, and

2D a schematic representation of a cross section along the line EF through the stack of four semiconductor devices in the further intermediate step of the method according to the embodiment.

Identical or equivalent components are each provided with the same reference numerals in the figures. The components shown and the size ratios of the components with each other are not to be considered as true to scale.

In the 1A in a supervision and in 1B in a cross section along the line AB illustrated semiconductor device 10 According to an embodiment, a semiconductor body 3 on, by one on a substrate 31 applied semiconductor layer sequence 32 is formed. The substrate 31 may in particular be a semiconductor substrate, for example a GaAs substrate. The substrate 31 is preferably electrically conductive and may in particular be doped, for example n-doped. The individual layers of the semiconductor layer sequence 32 are not shown individually for simplicity. The semiconductor layer sequence 32 In particular, it may have an active layer suitable for emitting radiation. By way of example, the semiconductor layer sequence has an n-type semiconductor region, a p-type semiconductor region and an active layer arranged therebetween.

The semiconductor body has a first main surface 11 and one of the first major surfaces 11 opposite second major surface 12 on. The first main area 11 has a recess 4 on, in which a first contact layer 1 for electrical contacting of the semiconductor body 3 is arranged. The depression 4 is in the substrate 31 of the semiconductor body 3 educated. A second contact layer 2 for electrical contacting of the semiconductor body 3 is on the opposite second major surface 12 arranged. The first contact layer is preferred 1 an n-side contact layer and the second contact layer 2 a p-side contact layer.

The depression 4 at the first main area 11 is advantageous in each case from the side surfaces 5 . 6 of the semiconductor body 3 spaced. The distance of the depression 4 from the side surfaces 5 . 6 is preferably at least 50 microns, for example 50 microns to 200 microns. The second contact layer 2 on the opposite second major surface 12 advantageously has an equal or greater distance from the side surfaces 5 . 6 on as the recess 4 , In particular, the second contact layer 2 in terms of their dimensions and their arrangement on the second major surface 12 executed such that a vertical projection of the second contact layer 2 on the first main surface 11 ie a projection perpendicular to the main surfaces 11 . 12 of the semiconductor body 3 completely inside the well 4 lies. The lateral dimensions of the second contact layer 2 in other words are less than or equal to the lateral dimensions of the recess 4 , The depression 4 has a depth which is greater than the sum of the thickness of the first contact layer 1 and the thickness of the second contact layer 2 ,

As a result, the first contact layer 1 and the second contact layer 2 not on the side surfaces 5 . 6 of the semiconductor body 3 adjoin the semiconductor body 3 inactive border areas 51 . 61 on that to the side surfaces 5 . 6 adjoin. Into the inactive border areas 51 . 61 no current is impressed during operation of the semiconductor device. Due to the inactive border areas 51 . 61 are the first contact layer 1 in the depression 4 and the second contact layer 2 from the side surfaces 5 . 6 spaced.

In the semiconductor device 10 is on a front page 15 and a back 16 one coating each 7 . 8th applied. The front 15 and the back 16 are each perpendicular to the main surfaces 11 . 12 and the side surfaces 5 . 6 , The coatings 7 . 8th may be in particular optical functional layers. The semiconductor device 10 is preferably an optoelectronic component, in particular a semiconductor laser such as a laser bar.

In the case of a semiconductor laser, the front side 15 and back 16 the semiconductor device 10 provided for forming a laser resonator. The coatings 7 . 8th may in particular be reflection-enhancing coatings. Alternatively, it is also possible that at least one of the coatings 7 . 8th is designed as a reflection-reducing coating, for. B. at a radiation decoupling surface of the semiconductor laser. The reflection-enhancing or reflection-reducing coating 7 . 8th can in particular be designed as a dielectric layer system which can have a plurality of partial layers. Alternatively, it is also possible that the coatings 7 . 8th have one or more layers of a metal or a metal alloy.

The semiconductor device 10 has the advantage that the coatings 7 . 8th particularly economical on the front 15 and / or back 16 can be applied. This clarifies that in the 2A and 2 B illustrated method for applying a coating to a plurality of semiconductor devices 10a . 10b . 10c . 10d , The semiconductor devices 10a . 10b . 10c . 10d at the in 2 described method correspond in terms of their structure and advantageous embodiments of related 1 described semiconductor device 10 ,

At the in 2A intermediate step shown are four semiconductor devices 10a . 10b . 10c . 10d stacked in such a way that each of the second major surface 12 a semiconductor device 10a a first main surface 11 another semiconductor device 10b is facing. The depression 4 at the first main area 11 the further semiconductor device 10b and the second major surface 12 the semiconductor device 10a together form a cavity 9 from which the second contact layer 2 the semiconductor device 10a and the first contact layer 1 the further semiconductor device 10b completely encloses. Characterized in that the depth of the recess is greater than the sum of the thicknesses of the first contact layer 1 and the second contact layer 2 , encloses the cavity 9 both contact layers 1 . 2 without these touching each other.

At the in 2 B The process step shown are coatings 7 . 8th on the fronts 15 and the backs 16 the semiconductor devices 10a . 10b . 10c . 10d been applied. Because of the contact layers 1 . 2 in the cavity 9 between the second major surface 12 and the first main surface 11 the adjacent semiconductor devices 10a . 10b . 10c . 10d are arranged, the risk is reduced, that this by an increased process temperature during application of the coatings 7 . 8th stick together.

To simplify the illustration are in the 2A and 2 B only four semiconductor devices arranged on top of each other 10a . 10b . 10c . 10d shown. In fact, in the practice of the method, however, a plurality of semiconductor devices may be stacked on top of each other where the front faces 15 and / or backsides 16 be coated at the same time.

In the method, it is advantageously not necessary between the stacked semiconductor devices 10a . 10b . 10c . 10d Use spacer to an adhesion of the adjacent semiconductor devices 10a . 10b . 10c . 10d at the contact layers 1 . 2 to prevent. Because such spacers are not present in the stack, the stack of semiconductor devices 10a . 10b . 10c . 10d for the same size of stack, comprise substantially more semiconductor devices than a stack of spacers. Thus, with the same effort more semiconductor devices can simultaneously with coatings 7 . 8th be provided. In particular, in this way reflection-reducing or reflection-increasing coatings 7 . 8th be applied simultaneously to a variety of laser bars.

The invention is not limited by the description with reference to the embodiments. Rather, the invention encompasses any novel feature as well as any combination of features, including in particular any combination of features in the claims, even if this feature or combination itself is not explicitly stated in the claims or exemplary embodiments.

Claims (13)

Semiconductor device ( 10 ) with a semiconductor body ( 3 ), which has a first main surface ( 11 ) and one of the first main surfaces ( 11 ) opposite second major surface ( 12 ), - a first contact layer ( 1 ) at the first main surface ( 11 ) and a second contact layer ( 2 ) on the second main surface ( 12 ), wherein - the semiconductor body ( 3 ) at the first main surface ( 11 ) a recess ( 4 ), which from two opposite side surfaces ( 5 . 6 ) of the semiconductor body ( 3 ) each have a spacing, - the first contact layer ( 1 ) completely in the depression ( 4 ), and the second contact layer ( 2 ) from the opposite side surfaces ( 5 . 6 ) equidistant or greater than the depression ( 4 ) having. Semiconductor device according to claim 1, wherein a vertical projection of the second contact layer ( 2 ) on the first main surface ( 11 ) of the semiconductor body completely within the recess ( 4 ) lies. Semiconductor device according to one of the preceding claims, wherein the recess ( 4 ) has a depth that is greater than the sum of a thickness of the first contact layer ( 1 ) and a thickness of the second contact layer ( 2 ). Semiconductor device according to one of the preceding claims, wherein a front side ( 15 ) and / or a back side ( 16 ) of the semiconductor device, a coating ( 7 . 8th ) having. Semiconductor device according to claim 4, wherein the coating ( 7 . 8th ) is a reflection-enhancing or a reflection-reducing coating. Semiconductor device according to one of the preceding claims, wherein the semiconductor device ( 10 ) is an optoelectronic device. A semiconductor device according to any one of claims 4 or 5, wherein the semiconductor device ( 10 ) is a semiconductor laser and the front ( 15 ) and the back ( 16 ) Form resonator mirrors of the semiconductor laser. Semiconductor device according to one of the preceding claims, wherein the semiconductor body ( 3 ) one on a substrate ( 31 ) applied semiconductor layer sequence ( 32 ), and wherein the recess ( 4 ) in the substrate ( 31 ) is trained. Semiconductor device according to one of the preceding claims, wherein the recess ( 4 ) a distance of at least 50 microns from the side surfaces ( 5 . 6 ) having. Method for applying a coating ( 7 . 8th ) to a plurality of semiconductor devices ( 10a . 10b . 10c . 10d )) according to any one of the preceding claims, comprising the steps of: - stacking the semiconductor devices ( 10a . 10b . 10c . 10d ) such that in each case the first main surface ( 11 ) a semiconductor device ( 10a ) and the second main surface ( 12 ) of an adjacent semiconductor device ( 10b ) are facing each other, wherein the recess ( 4 ) in the semiconductor body ( 3 ) of the semiconductor device ( 10 ) and the second main surface ( 12 ) of the adjacent semiconductor device ( 10 ) the first contact layer ( 1 ) of the semiconductor device ( 10 ) and the second contact layer ( 2 ) of the adjacent semiconductor device ( 10 ), and - applying a coating ( 7 . 8th ) on a front side ( 15 ) and / or a back side ( 16 ) of the stacked semiconductor devices ( 10a . 10b . 10c . 10d ). Process according to claim 10, wherein the coating ( 7 . 8th ) is a reflection-enhancing or a reflection-reducing coating. Method according to one of claims 10 or 11, wherein the semiconductor device ( 10 ) is an optoelectronic device. Method according to one of claims 10 to 12, wherein the semiconductor device ( 10 ) is a semiconductor laser and the front ( 15 ) and the back ( 16 ) Form resonator mirrors of the semiconductor laser.

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