JP2005197286A - Handling method of semiconductor thin film and manufacturing method of light-emitting element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for facilitating handling of a semiconductor thin film, and to provide a manufacturing method of a light-emitting element, based on the handling method. <P>SOLUTION: The handling method of a semiconductor thin-film wafer comprises a step of forming a first Au-based layer 91, principally comprising Au on the pasting surface 41 of a semiconductor thin film 4; a step of forming a second Au-based layer 10, principally comprising Au on the silicon dioxide pasting surface 110b of a temporary support board 110; a step of forming a temporary support multilayer body 100 for integrating the semiconductor thin film 4 and the temporary support substrate 110 by bonding the first Au-based layer 91 and the second Au-based layer 10 and handling the temporary support laminate 100, and a step for stripping the temporary support substrate 110 from the temporary support laminate 100 at the interface to the second Au-based layer 10. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a semiconductor thin film handling method and a light emitting device manufacturing method.

  In recent years, with the miniaturization and high performance of semiconductor elements, there is a demand for a technique for bonding very thin semiconductor thin films in the manufacturing process. Taking light-emitting elements such as light-emitting diodes and semiconductor lasers as examples, III-V compound semiconductors, such as light-emitting elements in which the light-emitting layer portion is formed of AlGaInP mixed crystals, use the fact that AlGaInP mixed crystals lattice-match with GaAs. Then, the light emitting layer portion made of AlGaInP mixed crystal can be epitaxially grown on the GaAs substrate. However, since the AlGaInP mixed crystal constituting the light emitting layer has a larger band gap than GaAs, the emitted light is absorbed by the GaAs substrate, and it is difficult to obtain sufficient light extraction efficiency. In order to solve this problem, various publications including Patent Document 1 disclose a technique in which a growth element GaAs substrate is peeled off, and then a reinforcing element substrate is bonded to a peeling surface through an Au layer. Has been. At this time, the compound semiconductor layer (semiconductor thin film) including the light emitting layer portion from which the GaAs substrate has been peeled may be very thin with a thickness of about 50 μm or less (for example, 30 μm).

JP 2001-339100 A

  In order to obtain a light emitting element by bonding as described above, it is necessary to handle a very thin semiconductor thin film in many processes including the bonding process. However, such a semiconductor thin film is often damaged when it is handled while being sandwiched by means such as tweezers.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a handling method capable of easily handling a semiconductor thin film and a method for manufacturing a light emitting device based thereon.

Means for solving the problems / effects of the invention

In order to solve the above problems, in the semiconductor thin film handling method of the present invention,
Forming a first Au-based layer mainly composed of Au on the bonding surface of the semiconductor thin film;
Forming a second Au-based layer mainly composed of Au on the bonding surface made of silicon dioxide of the temporary support substrate;
Bonding the first Au-based layer and the second Au-based layer, forming a temporary support laminate in which the semiconductor thin film and the temporary support substrate are integrated, and handling the temporary support laminate;
Peeling the temporary support substrate from the temporary support laminate at the interface with the second Au-based layer;
It is characterized by having.
In the present specification, the “main component” refers to a component having the highest mass content.

  According to the method for handling a semiconductor thin film of the present invention, the first and second Au-based layers are formed on the bonding surfaces of the semiconductor thin film and the temporary support substrate, and these are combined to form a temporary support laminate. Form. By handling a very thin semiconductor thin film in the state of a temporary support laminate, the semiconductor thin film is reinforced and protected by a temporary support substrate bonded to the semiconductor thin film, so that it can be handled easily. The Au-based layers are bonded to each other by pressurization at room temperature, but may be heated at the time of bonding.

Since the bonding surface made of silicon dioxide (SiO ₂ ) of the temporary support substrate has poor adhesion to the Au-based layer, the temporary support substrate is used as the second Au-based layer in the temporary support laminate after the handling of the semiconductor thin film. It can be easily peeled off at the interface. Thereby, the peeled temporary support substrate can be used for handling a new semiconductor thin film. When it is not necessary to leave the Au-based layer on the bonding surface of the semiconductor thin film, the second Au-based layer remaining on the bonding surface of the semiconductor thin film can be removed after the temporary support substrate is peeled off.

  As the temporary support substrate, a silicon substrate having a bonded surface covered with silicon dioxide can be used. Silicon (Si) forms a very good quality oxide film on the surface layer, but such an oxide film is inactive to the Au-based layer and has low adhesion to the Au-based layer. Very suitable for bonding surfaces.

The semiconductor thin film handling method described above can be applied to the manufacture of a light-emitting element having a bonding step.
That is, in the method for manufacturing a light emitting device of the present invention,
On the first main surface of the compound semiconductor layer having the light emitting layer portion formed on the substrate for growing the light emitting layer portion, the first Au-based layer containing Au as a main component is formed, and the temporary support substrate is made of silicon dioxide. A temporary support Au-based layer forming step of forming a second Au-based layer containing Au as a main component on the bonding surface;
A temporary support laminate forming step in which the first Au-based layer and the second Au-based layer are bonded to form a temporary support laminate in which the compound semiconductor layer and the temporary support substrate are integrated;
An element substrate bonding step of removing the growth substrate from the temporary support laminate to expose the second main surface of the compound semiconductor layer and bonding an element substrate to the second main surface;
A temporary support substrate removing step of peeling the temporary support substrate at the interface with the second Au-based layer;
Are performed in this order.

  According to the method for manufacturing a light emitting element of the present invention, when the substrate for growing the light emitting layer portion is removed from the compound semiconductor as the semiconductor thin film and the element substrate is bonded to the removal surface, as in the semiconductor thin film handling method described above. The semiconductor thin film can be easily handled.

  As the temporary support substrate, a silicon substrate having a bonded surface covered with silicon dioxide can be used. As described above, silicon (Si) forms a very good quality oxide film on the surface layer, but such an oxide film is inactive with respect to the Au-based layer and has poor adhesion with the Au-based layer. It is very suitable for the bonding surface of the temporary support substrate.

  In the element substrate bonding step, the light emitting layer portion side Au-based layer is formed on the second main surface of the compound semiconductor layer in the state of the temporary support laminate, and the element substrate side Au-based layer is formed on the bonding surface of the element substrate. This can be done by bonding the part-side Au-based layer and the element substrate-side Au-based layer. Since the Au-based layers are easily integrated even at a relatively low temperature, a light emitting element having a sufficient bonding strength can be obtained even when the heat treatment temperature for bonding is low.

  Further, the first Au-based layer formed on the first main surface of the compound semiconductor layer can be used as an electrode for applying a light emission driving voltage to the light emitting layer portion. This makes it possible to simplify the manufacturing process.

Embodiments of a semiconductor thin film handling method and a light emitting device manufacturing method according to the present invention will be described below with reference to the drawings.
First, an example of a light-emitting element 1 obtained by the method for manufacturing a light-emitting element of the present invention is shown in FIG. The light emitting element 1 has a structure in which a light emitting layer portion 2 is bonded to a first main surface 71 of a silicon substrate 7 made of n-type Si single crystal as an element substrate via an Au-based layer 5 containing Au as a main component. It has.

The light emitting layer portion 2 includes an active layer 21 made of a non-doped (Al _x Ga _1-x ) _y In _1-y P (where 0 ≦ x ≦ 0.55, 0.45 ≦ y ≦ 0.55) mixed crystal. , the first-conductivity-type cladding layer, a p-type _{(Al z Ga 1-z)} y in 1-y P ( except x <z ≦ 1) p-type cladding layer 23 made of the present embodiment, the first-conductivity-type cladding the second-conductivity-type cladding layer different from the layer, sandwiched by the n-type _{(Al z Ga 1-z)} y in 1-y P ( except x <z ≦ 1) n-type cladding layer 22 made of the present embodiment Depending on the composition of the active layer 21, the emission wavelength can be adjusted in the green to red region (the emission wavelength (peak emission wavelength) is 550 nm or more and 670 nm or less). In the light emitting element 1, the p-type AlGaInP cladding layer 23 is disposed on the metal electrode 91 side, and the n-type AlGaInP cladding layer 22 is disposed on the Au-based layer 5 side. Therefore, the conduction polarity is positive on the metal electrode 91 side. The term “non-dope” as used herein means “does not actively add dopant”, and contains a dopant component inevitably mixed in a normal manufacturing process (for example, 10 ¹³ to 10 ¹⁶ / cm 3). It is not excluded that the upper limit is about ³ ). On the contrary, the p-type cladding layer 23 can be the Au-based layer 5 side and the n-type cladding layer 22 can be the metal electrode 91 side. In this case, the energization polarity is reversed, and the other members have a conductivity type opposite to that shown in the figure.

  A current diffusion layer 3 made of AlGaAs is formed on the main surface of the light emitting layer 2 opposite to the side facing the silicon substrate 7, and the light emitting layer 2 is substantially at the center of the main surface 41. For example, a metal electrode 91 in which an Au layer 91b is formed on an AuBe layer 91a is formed so as to cover a part of the main surface 41 in order to apply a light emission driving voltage. A region around the metal electrode 91 on the main surface 41 of the current diffusion layer 3 forms a light extraction region PF from the light emitting layer portion 2. Hereinafter, a layer body composed of the light emitting layer portion 2 and the current diffusion layer 3 is referred to as a compound semiconductor layer 4. The metal electrode 91 is formed on the first main surface side of the compound semiconductor layer 4. Further, a metal electrode (back electrode: for example, an Au electrode) 92 is formed on the second main surface 72 side of the silicon substrate 7 so as to cover the entire surface. An AuSb bonding alloying layer 63 is interposed between the metal electrode 92 and the silicon substrate 7. Further, AuSn may be used as the bonding alloying layer instead of AuSb.

  The silicon substrate 7 is manufactured by slicing and polishing a Si single crystal ingot, and the thickness thereof is, for example, 100 μm or more and 500 μm or less. Then, it is bonded to the light emitting layer portion 2 with the Au-based layer 5 interposed therebetween. The Au-based layer 5 includes a light-emitting layer portion-side Au-based layer 5 a formed on the second main surface side of the compound semiconductor layer 4 and an element substrate-side Au-based layer 5 b formed on the first main surface side of the silicon substrate 7. Bonded by bonding heat treatment.

  An AuGeNi bonding layer 61 (for example, Ge: 15% by mass, Ni: 10% by mass) is formed between the light emitting layer part 2 and the light emitting layer part side Au-based layer 5a, which contributes to reducing the series resistance of the device. doing. The AuGeNi bonding layer 61 is dispersedly formed on the main surface of the light emitting layer portion side Au-based layer 5a, and the formation area ratio thereof is 1% or more and 25% or less. An AuSb bonding layer 62 (for example, Sb: 5% by mass) is interposed between the silicon substrate 7 and the element substrate-side Au-based layer 5b. Note that AuSn may be used as the bonding layer instead of AuSb.

  The AuSb bonding metal layer 62 is covered with a Ti (titanium) layer 8 in order to prevent the Si component from the silicon substrate 7 from diffusing into the Au-based layer 5. An Au-based layer 5 is disposed so as to cover the entire surface of the Ti layer 8 so as to be in contact therewith. In the present embodiment, the Au-based layer 5 is made of pure Au or an Au alloy having an Au content of 95% by mass or more.

  The light from the light emitting layer portion 2 is extracted in such a manner that the light reflected directly from the light extraction surface side is superimposed with the light reflected by the Au-based layer 5. The thickness of the Au-based layer 5 is desirably 80 nm or more in order to ensure a sufficient reflection effect.

Hereinafter, a method for manufacturing the light-emitting element 1 of FIG. 1 will be described.
First, as shown in Step 1 of FIG. 2, an n-type GaAs buffer layer 12 is 0.5 μm, for example, and a release layer 13 made of AlAs is formed on the main surface of a GaAs single crystal substrate 11 which is a light emitting layer portion growth substrate. Epitaxial growth is performed in this order at 0.5 μm. Thereafter, an n-type AlGaInP clad layer 22 of about 1 μm, an AlGaInP active layer (non-doped) 21 of about 0.6 μm, and a p-type AlGaInP clad layer 23 of about 1 μm are epitaxially grown in this order as the light emitting layer portion 2. Further, the current diffusion layer 3 made of p-type AlGaAs is epitaxially grown by 5 μm, for example. Thereby, the compound semiconductor layer 4 including the light emitting layer portion 2 and the current diffusion layer 3 is formed on the GaAs single crystal substrate 11. The compound semiconductor layer 4 has a thickness of about 8 μm and is difficult to handle by itself.

  A first Au-based layer 91 containing Au as a main component is formed on the first main surface 41 of the compound semiconductor layer 4. The first Au-based layer 91 is formed in a dot shape, and is used as an electrode for applying a light emission driving voltage to the light emitting layer portion 2 later. The first Au-based layer 91 is formed, for example, by forming an Au layer 91b on an AuBe layer 91a.

  Next, as shown in Step 2, the second Au-based layer 10 containing Au as a main component is formed on the bonding surface 110b of the temporary support substrate 110 for temporarily supporting and handling the compound semiconductor layer 4 ( Thus, the temporary support Au-based layer forming step). The formation of the first Au-based layer and the second Au-based layer in the above steps can be performed using sputtering or vacuum deposition. The temporary support substrate 110 is made of a silicon substrate in which the bonding surface 110b is covered with a silicon dioxide film.

  Next, as shown in step 3, the first Au-based layer 91 and the second Au-based layer 10 are pressed and bonded at room temperature, and the compound semiconductor layer 4 and the silicon substrate (temporary support substrate) 110 are integrated. The temporary support laminate 100 thus formed is formed (the temporary support laminate formation step). Since this temporary support laminated body formation process is performed in the state where the GaAs single crystal substrate 11 which is a light emitting layer part growth substrate is accompanied with the compound semiconductor 4, the temporary support laminated body 100 formed here is shown in a figure. Thus, the shape is formed on the GaAs single crystal substrate 11.

  Next, as shown in step 4 of FIG. 3, the GaAs single crystal substrate 11 which is a light emitting layer portion growth substrate attached to the temporary support laminate 100 is removed. This is because the temporary support laminated body 100 (see step 3) accompanied with the GaAs single crystal substrate 11 is immersed in an etching solution made of, for example, a 10% hydrofluoric acid aqueous solution, and between the buffer layer 12 and the light emitting layer portion 2. The GaAs single crystal substrate 11 (which is opaque to the light from the light emitting layer portion 2) is peeled off from the temporary support laminate 100 by selectively etching the AlAs release layer 13 formed on the substrate. It should be noted that an etch stop layer made of AlInP is formed in place of the AlAs release layer 13, and a GaAs single crystal is used by using a first etching solution (for example, ammonia / hydrogen peroxide mixed solution) having selective etching properties with respect to GaAs. Etch and remove the substrate 11 together with the GaAs buffer layer 12 and then etch stop using a second etchant that has selective etching properties with respect to AlInP (for example, hydrochloric acid: hydrofluoric acid may be added to remove the Al oxide layer). A step of etching away the layer can also be employed. Even after being separated from the GaAs single crystal substrate 11, the compound semiconductor layer 4 having a thickness of about 8 μm is supported by the temporary support substrate 110, and can be easily handled in the state of the temporary support laminate 100.

  Next, an element substrate bonding step shown in steps 5 and 6 is performed. In the element substrate bonding step, the light emitting layer side Au-based layer 5a is formed on the second main surface 42 of the compound semiconductor layer 4 in the state of the temporary support laminate 100, and the bonding surface of the silicon substrate 5b as the element substrate is formed. The element substrate-side Au-based layer 5b is formed, and the light-emitting layer portion-side Au-based layer 5a and the element substrate-side Au-based layer 5b are pressed and bonded while being heated.

  Specifically, as shown in step 5, the AuGeNi bonding layer 61 is dispersedly formed on the second main surface 42 of the light emitting layer portion 2. After the AuGeNi bonding layer 61 is formed, an alloying heat treatment is performed in a temperature range of 350 ° C. or higher and 500 ° C. or lower, and then the light emitting layer portion side Au-based layer 5a is formed so as to cover the AuGeNi bonding layer 61. An alloying layer is formed between the light emitting layer portion 2 and the AuGeNi bonding layer 61 by the alloying heat treatment, and the series resistance is greatly reduced. On the other hand, AuSb bonding layers 62 and 63 (which may be AuSn bonding layers as described above) are formed on both main surfaces of a silicon substrate 7 (n-type), which is a separately prepared element substrate, and a temperature of 250 ° C. or more and 359 ° C. or less. Alloying heat treatment is performed in the region. Subsequently, a Ti layer 8 functioning as a Si diffusion blocking layer is formed on the AuSb bonding layer 62. Then, the element substrate side Au-based layer 5b is formed on the Ti layer 8, and the back electrode layer 92 (for example, made of Au-based metal) is formed on the AuSb bonding layer 63. In the above steps, each metal layer can be formed by sputtering or vacuum deposition.

  Then, as shown in Step 6, the light emitting layer portion side Au-based layer 5a formed on the light emitting layer portion 2 side is superimposed on the element substrate side Au-based layer 5b formed on the silicon substrate 7 side and pressed, The bonding is performed by heating at a temperature higher than 180 ° C. and 360 ° C. or lower, for example, 250 ° C. As a result, the light emitting layer portion side Au-based layer 5a and the element substrate side Au-based layer 5b are bonded with sufficient strength.

  Next, a temporary support substrate removing step shown in steps 7 and 8 in FIG. 4 is performed. First, as shown in step 7, for example, a little edge is inserted between the temporary support silicon substrate 110 and the compound semiconductor layer 4, and the temporary support substrate 110 is peeled from the temporary support laminate 100. At this time, peeling occurs at the interface between the temporary support substrate 110 and the second Au-based layer 10. Thereafter, as shown in Step 8, the second Au-based layer 10 remaining on the first main surface 41 of the compound semiconductor layer 4 is removed by, for example, spraying high-pressure gas. The first Au-based layer 91 left on the first main surface 41 of the compound semiconductor layer 4 is used as a metal electrode for applying a light emission driving voltage to the light emitting unit 2.

  Then, the final light emitting device 1 is obtained by dicing the semiconductor chip by a usual method, fixing this to a support, performing wire bonding of a lead wire, etc., and then sealing with a resin. .

Schematic showing the structure of the light emitting element obtained by the manufacturing method of the light emitting element of this invention Process drawing showing the manufacturing method of the light emitting element of this invention Process diagram following FIG. Process diagram following FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Light emitting element 2 Light emitting layer part 3 Current spreading layer 4 Compound semiconductor layer 5 Au system layer 5a Light emitting layer part side Au system layer 5b Element substrate side Au system layer 7 Element substrate (silicon substrate)
10 Second Au-based layer 11 Light emitting layer growth substrate (GaAs single crystal substrate)
91 First Au-based layer, electrode 100 Temporary support laminate 110 Temporary support substrate (temporary support silicon substrate)
111 Silicon dioxide film

Claims (7)

Forming a first Au-based layer mainly composed of Au on the bonding surface of the semiconductor thin film;
Forming a second Au-based layer mainly composed of Au on the bonding surface made of silicon dioxide of the temporary support substrate;
Bonding the first Au-based layer and the second Au-based layer, forming a temporary support laminate in which the semiconductor thin film and the temporary support substrate are integrated, and handling the temporary support laminate;
Peeling the temporary support substrate from the temporary support laminate at the interface with the second Au-based layer;
A method for handling a semiconductor thin film, comprising:   The method for handling a semiconductor thin film according to claim 1, wherein the second Au-based layer on the semiconductor thin film is removed after the temporary support substrate is peeled off.   3. The method for handling a semiconductor thin film according to claim 1, wherein the temporary support substrate is a silicon substrate having a bonded surface covered with silicon dioxide. On the first main surface of the compound semiconductor layer having the light emitting layer portion formed on the substrate for growing the light emitting layer portion, the first Au-based layer containing Au as a main component is formed, and the temporary support substrate is made of silicon dioxide. A temporary support Au-based layer forming step of forming a second Au-based layer containing Au as a main component on the bonding surface;
A temporary support laminate forming step in which the first Au-based layer and the second Au-based layer are bonded to form a temporary support laminate in which the compound semiconductor layer and the temporary support substrate are integrated;
An element substrate bonding step of removing the growth substrate from the temporary support laminate to expose the second main surface of the compound semiconductor layer and bonding an element substrate to the second main surface;
A temporary support substrate removing step of peeling the temporary support substrate at the interface with the second Au-based layer;
Are performed in this order. A method for manufacturing a light-emitting element.   The method for manufacturing a light emitting element according to claim 4, wherein the temporary support substrate is a silicon substrate having a bonded surface covered with silicon dioxide.   In the element substrate bonding step, the light emitting layer side Au-based layer is formed on the second main surface of the compound semiconductor layer in the state of the temporary support laminate, and the element substrate side Au-based layer is formed on the bonding surface of the element substrate. 6. The method for manufacturing a light-emitting element according to claim 4, wherein the light-emitting element side Au-based layer is formed and bonded to the element substrate-side Au-based layer.   7. The first Au-based layer formed on the first main surface of the compound semiconductor layer is used as an electrode for applying a light emission driving voltage to the light emitting layer portion. The manufacturing method of the light emitting element of any one.

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