JP2005158787A - Manufacturing method for semiconductor device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve a throughput of manufacturing devices by increasing the number of manufacture of semiconductor devices manufactured per one substrate used for the epitaxial growth of the compound semiconductor devices. <P>SOLUTION: A manufacturing method for a semiconductor device has a step for forming a first intermediate layer 2 for isolating the semiconductor substrate 1 and a semiconductor device layer 3 on the semiconductor substrate 1, and the step for forming the semiconductor device layer 3 epitaxial-growing a semiconductor structure on the layer 2. The manufacturing method further has the step for forming a second intermediate layer 4 for isolating the layer 3 and the semiconductor device layer 5 on the layer 3, and the step for forming the layer 5 epitaxial-growing the semiconductor structure on the layer 4. The manufacturing method further has the step for carrying out the step for forming the layer 4, the step for forming the layer 5 on the layer 4 at least once or more, and the step for isolating the layer 3 and the layer 5 through the layer 4 for isolating a plurality of the semiconductor devices. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a manufacturing method that improves throughput and reduces cost in a technique for thinning an epitaxially grown semiconductor device, and particularly relates to a light emitting device, a light receiving device, and a solar cell in which carrier flow operates in a vertical direction. The present invention relates to a method for manufacturing a thin film semiconductor device for cost reduction.

  In the case of an element that requires a large amount of an epitaxial film such as a solar cell, the material cost and the element manufacturing time are required to be as small as possible. Of these, the cost of the substrate is large in terms of material cost. Therefore, development is made to reduce the material cost by methods such as thinning the substrate after element formation or peeling the substrate from the element and reusing it. It is. Among them, the method that leads to the most cost reduction is a method of separating the substrate from the element and reusing it.

  Specifically, as described in Non-Patent Document 1 below, there is a technique in which one intermediate layer and an element are formed on a substrate, and the intermediate layer is melted to peel the element. However, in this method, when the substrate after peeling is reused, it is necessary to repeat the steps of cleaning the surface of the substrate by lapping, etching, or the like, and reusing the substrate to grow the intermediate layer and the element. Therefore, in this method, in order to grow the intermediate layer and the element once, it is necessary to perform one substrate surface treatment.

Further, when an element is manufactured by epitaxial growth, conventionally, a process such as a temperature rise to a substrate growth temperature, a temperature drop, and a substrate unloading are always required for one element growth. As described above, in order to grow the intermediate layer and the element once, if one surface treatment of the substrate is required or a step such as a temperature rise is required for the single element growth, it is very difficult to manufacture a semiconductor element. It takes a long time, and the cost per element becomes very expensive.
“High rate epitaxial lift-off of InGaP films from GaAs substrate”, J. MoI. J. et al. Schermer, et al, Appl. Phys. Lett. Vol. 15, page 2131.

  The present invention relates to a method of increasing the number of semiconductor elements that can be manufactured per substrate used for epitaxial growth of compound semiconductor elements to improve the throughput of manufacturing the elements, and a plurality of semiconductor elements grown on the substrate A method of thinning the film is provided. Specifically, it is necessary to clean the substrate surface, such as lapping and etching, which is required every time the device is grown, and to increase costs by limiting the number of times the substrate can be reused, and to grow the device. It is intended to increase the efficiency of the steps of raising and lowering the temperature to the substrate growth temperature and carrying the substrate in and out.

  According to the method for manufacturing a semiconductor element of the present invention, a step of forming a first intermediate layer for separating the semiconductor substrate and the semiconductor element layer on a semiconductor substrate, and a semiconductor structure on the first intermediate layer. Forming a semiconductor element layer formed by epitaxially growing the semiconductor element, forming a second intermediate layer on the semiconductor element layer for separating the semiconductor element layer and the semiconductor element layer, and the second intermediate Forming a semiconductor element layer formed by epitaxially growing a semiconductor structure on the layer; forming the second intermediate layer; and forming the semiconductor element layer on the second intermediate layer at least once. And a step of separating the semiconductor element layer and the semiconductor element layer through a second intermediate layer for separating the semiconductor element and the semiconductor element.

  Preferably, the semiconductor element is a compound semiconductor element or a solar cell.

  Preferably, an etching solution that does not erode the substrate is used for etching the intermediate layer, so that the substrate is used as a supporting substrate and is peeled off from the element in the epitaxial surface direction, or an etching solution that erodes the substrate for etching the intermediate layer. Is used to erode the substrate, attach the supporting substrate to the epitaxial surface, and peel the substrate from the device.

  Preferably, a barrier layer that does not erode with the etching solution used for etching the intermediate layer is formed in a layer in contact with the intermediate layer.

  According to the method for manufacturing a semiconductor device of the present invention, the number of semiconductor devices that can be manufactured per substrate can be increased. Therefore, cleaning of the substrate surface, such as lapping and etching, required for each device growth is possible. The number of times can be reduced and the time efficiency is increased. In addition, it is possible to suppress an increase in cost due to the limitation on the number of times the substrate is reused due to the processing of the substrate. In addition, the process of carrying in / out the substrate can be made highly efficient.

  A method of manufacturing a semiconductor device of the present invention includes a step of forming a first intermediate layer for separating a semiconductor substrate and a semiconductor device layer on a semiconductor substrate, and epitaxially growing a semiconductor structure on the first intermediate layer. Forming a semiconductor element layer formed thereon, forming a second intermediate layer for separating the semiconductor element layer and the semiconductor element layer on the semiconductor element layer, and on the second intermediate layer In addition, a step of forming a semiconductor element layer formed by epitaxially growing a semiconductor structure, a step of forming the second intermediate layer, and a step of forming a semiconductor element layer on the second intermediate layer are executed at least once. And a step of separating the semiconductor element layer and the semiconductor element layer through a second intermediate layer for separating the semiconductor element and the semiconductor element. Here, the semiconductor element includes a compound semiconductor element, specifically, a single or plural solar cells such as a solar cell (GaAs solar cell, InGaAs solar cell, InGaP solar cell, AlInGaP solar cell, InGaNAs solar cell). Multi-junction solar cells connected by tunnel junctions). In the present invention, the first intermediate layer is an intermediate layer for separating the semiconductor substrate and the semiconductor element layer, and the second intermediate layer is for separating the semiconductor element layer and the semiconductor element layer. Refers to the middle layer. The materials for the semiconductor substrate and the intermediate layer can be appropriately selected according to the semiconductor element to be manufactured.

  FIG. 1 shows a cross-sectional view of a structure in which two semiconductor elements are formed on a semiconductor substrate in the method for manufacturing a semiconductor element of the present invention. In FIG. 1, a first intermediate layer 2 for separating the semiconductor substrate 1 and the semiconductor element layer 3 is formed on the semiconductor substrate 1, and the semiconductor element layer 3 is formed on the first intermediate layer 2. The second intermediate layer 5 for separating the semiconductor element and the semiconductor element is formed on the semiconductor element layer 3. The first and second intermediate layers and the semiconductor element layer 3 can be formed using a method known in the art, and specifically, an epitaxial growth method such as MOCVD method, MBE method, or the like can be used. .

  In the structure of FIG. 1, the semiconductor element layer 5 can be peeled off by covering the side surface portion with wax or the like, etching the second intermediate layer 4 as necessary. Next, the first intermediate layer 2 can be etched to separate the semiconductor substrate 1 and the semiconductor element layer 3.

  In the present invention, at least one or more of the second intermediate layer and the semiconductor element layer formed thereon can be formed on the semiconductor substrate. By forming one or more in this way, other semiconductor element layers can be grown while the semiconductor element layer is being peeled off, the manufacturing time efficiency is greatly improved, and the manufacturing per semiconductor substrate is possible. As the number of semiconductor element layers increases, the manufacturing efficiency of semiconductor elements per semiconductor substrate is greatly improved.

  Hereinafter, the present invention will be specifically described by taking a solar cell as an example of a semiconductor element, but is not limited thereto.

  FIG. 2 is a cross-sectional view of a solar cell element formed in two layers. In FIG. 2, a first intermediate layer 22 is formed using an AlAs material on a semiconductor substrate 21 using a GaAs material, and a solar cell 23 using an InGaP material as a semiconductor element layer is reversed on the first intermediate layer 22. To form. Further, a second intermediate layer 24 using an AlAs material is formed on the solar cell 23, and a solar cell 25 using an InGaP material as a semiconductor element layer is formed on the second intermediate layer 24. The solar cells 23 and 25 are configured such that n-AlInP layers 7 and 12 are formed on n-GaAs layers 6 and 11, respectively, and n-InGaP layers 8 and 13 are formed on the n-AlInP layers 7 and 12, respectively. The p-InGaP layers 9 and 14 are formed on the n-InGaP layers 8 and 13, respectively, and the p + -InGaP layers 10 and 15 are formed on the p-InGaP layers 9 and 14, respectively. .

When forming the solar cell, the epitaxial growth can be performed using a metal organic chemical vapor deposition (MOCVD) method, and the growth temperature can be set to 700 ° C. For the growth of the GaAs layers 6 and 11, trimethyl gallium (TMG) and arsine (AsH ₃ ) can be used as raw materials. For the growth of the InGaP layers 8, 9, 13, and 14, trimethylindium (TMI), TMG, and phosphine (PH ₃ ) can be used as raw materials. The growth of the AlInP layer 7, 12, trimethyl aluminum as a raw material (TMA), can be used TMI and PH _3. For the growth of the first and second intermediate layers 22 and 24, TMA and AsH ₃ can be used as raw materials. In all the growth of GaAs, InGaP and AlInP layers, SiH ₄ (monosilane) can be used as an impurity for forming an n-type layer, and DEZn can be used as an impurity for forming a p-type layer.

  The side surface portion of the epitaxial film formed as shown in FIG. 2 is covered with wax 18 and a predetermined pattern is formed by photolithography. Then, the GaAs layer 11 of the upper solar cell 25 is etched using an alkaline solution, and the InGaP layer 13 is etched. ˜15 and the AlInP layer 12 are etched with an acid solution to expose the surface of the second intermediate layer 24. As the wax, Apiezon wax can be used.

  Next, the back electrode 16 is formed on the upper InGaP solar cell as the semiconductor element 25, and the support substrate 17 is bonded with wax so as to have the structure of FIG. FIG. 3 is a cross-sectional view of a solar cell element in which a support substrate is attached to the upper solar cell.

  Next, by etching the second intermediate layer 24 from the side surface using a 10% HF solution, the upper InGaP solar cell as the semiconductor element 25 can be peeled, and the structure of FIG. 4 can be obtained. FIG. 4 is a cross-sectional view of the peeled upper solar cell element.

  Similarly, the lower InGaP solar cell as the semiconductor element 23 is also peeled off from the semiconductor substrate 21 made of a GaAs material.

After the solar cells as the semiconductor elements 23 and 25 are peeled off as described above, the respective solar cells are patterned by a photolithography method to form Au—Ge / Ni / Au electrodes. Further, a TiO ₂ film and an MgF ₂ film are continuously formed on the surface as an antireflection film by EB vapor deposition. The film thicknesses of the TiO ₂ film and the MgF ₂ film can be set to, for example, 55 nm and 100 nm, respectively.

  FIG. 5 shows the results of evaluation of the InGaP solar cell thus obtained, which was prepared to have a size of 1 × 1 cm. FIG. 5 is a graph showing the IV characteristics of the solar cell in the present invention. Here, the horizontal axis X represents voltage (V), and the vertical axis Y represents current (A). As can be seen from FIG. 5, the InGaP solar cell according to the present invention exhibits almost the same characteristics as an InGaP solar cell fabricated on a conventional p-type GaAs substrate.

  In the present invention, when a compound containing AlAs is used as the material of the element uppermost layer or the element lowermost layer, since the material of the intermediate layer is AlAs, the intermediate layer can be selectively etched when the intermediate layer is etched. However, the device layer made of the compound containing AlAs cannot be etched. Therefore, in such a case, by inserting a layer such as InGaP between the element and the intermediate layer made of the AlAs material, the InGaP layer serves as a stopper layer, and when the intermediate layer is etched, Erosion can be prevented.

(efficiency)
Usually, an MOCVD apparatus for epitaxially growing an InGaP solar cell has a 2 inch φ × 1 piece furnace. When epitaxial growth is performed using this apparatus, the time required for producing one InGaP solar cell is 3 hours. The actual growth time is about 30 minutes, and the time required for growth other than growth, such as transfer, vacuuming, and heating up to the growth temperature when the substrate is installed in the apparatus, is about 2.5 hours. It is the total of the time.

  In the present invention, the time for peeling the solar cell from the substrate is about 1 cm / hour at which the AlAs intermediate layer is dissolved. The distance is 2.5 cm and it takes about 2.5 hours. Further, it takes about 0.5 hour to form the back electrode. Therefore, in the present invention, the time (about 3 hours) that combines the time for forming the back electrode and the time for peeling from the substrate is substantially the same as the time for epitaxial growth, so that one solar cell is peeled off during the epitaxial growth. Can do.

  Specifically, in the case of epitaxially growing 10 InGaP solar cells, in the normal growth method, as described above, since the growth time of 1 sheet is 3 hours, the time required for the growth of 10 sheets is 30 hours. For each of the 10 solar cells after growth, when the back electrode is formed and peeled off from the substrate, the time required to produce the structure shown in FIG. 3 is about 33 hours. There are about 10 substrates.

  In the present invention, for example, when 10 InGaP solar cells are epitaxially grown, four InGaP solar cells are first grown on one substrate. The time required for this growth is 4.5 hours, and this time is 2 hours for the actual growth time of 0.5 hours × 4 layers, and the time required for other than the growth is 2.5 hours. It is the total time. Next, three layers of InGaP solar cells are grown using another substrate. The time required for this growth is 1.5 hours for a growth time of 0.5 hours × 3 layers, and the time required for other than the growth is 2.5 hours, for a total of 4 hours. While the three layers of solar cells are being grown, a back electrode is formed on one layer of the InGaP solar cells on which four layers of solar cells have already been grown and peeled off from the substrate. Since the total of the back electrode formation time and the peeling time for one solar cell layer is 3 hours as described above, the back electrode formation and peeling from the substrate are performed while another solar cell three layers are grown. Because it can.

  Next, two layers of InGaP solar cells are grown using another substrate. The time required for this growth is 0.5 hour × 1 hour for two layers, and the time required for other than growth is 2.5 hours and 3.5 hours. During the growth, in the same manner as described above, one of the three layers of InGaP solar cells is subjected to back electrode formation and peeling from the substrate. Here, the three-layer InGaP solar cell includes two solar cells, one of which is a three-layered InGaP solar cell formed in four layers and the other of an InGaP solar cell formed in three layers. Includes batteries.

  Next, an InGaP solar cell layer is grown on another substrate. The time required for the growth is 0.5 hour × 0.5 hour for one layer, and the other time is 2.5 hours for a total of 3 hours. During the growth, one layer of each of the two InGaP solar cells is peeled off. Here, in the two-layer InGaP solar cell, two layers of the InGaP solar cell formed in four layers are peeled to become two layers, and one layer in the three-layered InGaP solar cells is formed. It includes a layer that has been peeled to form two layers and an InGaP solar cell that has been formed to have two layers.

  Finally, the one-layer InGaP solar cell is peeled off from the substrate. The time required for the peeling is 3 hours as described above. In the one-layer InGaP solar cell, three of the InGaP solar cells formed in four layers are peeled to become one layer, and two of the InGaP solar cells formed in three layers are peeled off. The four InGaP solar cells of the InGaP solar cell formed in one layer, that is, one layer formed by peeling one layer out of the InGaP solar cells formed in two layers. A battery is included.

  The number of InGaP solar cells thus formed is 10 and the required time is 18 hours. Therefore, by using the method for manufacturing a thin film semiconductor element of the present invention, the time can be shortened to about half that of a normal method for manufacturing a solar cell. Further, since the number of used substrates is four and the number of normal semiconductor element manufacturing methods is ten, it can be reduced to about half or less. The embodiment disclosed this time should be considered as illustrative in all points and not restrictive.

  The scope of the present invention is defined by the terms of the claims, rather than the appended description, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

In the manufacturing method of the semiconductor device of the present invention, it is a sectional view of the structure where two semiconductor devices were formed on the semiconductor substrate. It is sectional drawing of the solar cell element formed in two layers. It is sectional drawing of the solar cell element with which the support substrate was attached to the upper InGaP solar cell. It is sectional drawing of the peeled upper solar cell element. It is a figure showing the IV characteristic of the solar cell in this invention using a graph.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Semiconductor substrate, 2 1st intermediate | middle layer, 3, 5, 23, 25 Semiconductor element, 4 2nd intermediate | middle layer, 6,11 n-GaAs layer, 7,12 n-AlInP layer, 8,13 n-InGaP layer, 9,14 p-InGaP layer, 10,15 p + -InGaP layer, 16 back electrode, 17 support substrate, 18 wax.

Claims (6)

Forming a first intermediate layer on the semiconductor substrate for separating the semiconductor substrate and the semiconductor element layer;
Forming a semiconductor element layer formed by epitaxially growing a semiconductor structure on the first intermediate layer;
Forming a second intermediate layer for separating the semiconductor element layer and the semiconductor element layer on the semiconductor element layer;
Forming a semiconductor element layer formed by epitaxially growing a semiconductor structure on the second intermediate layer;
Executing the step of forming the second intermediate layer and the step of forming a semiconductor element layer on the second intermediate layer at least once;
Separating the semiconductor element layer and the semiconductor element layer through a second intermediate layer for separating the semiconductor element and the semiconductor element;
A method for manufacturing a semiconductor device comprising:   The method of manufacturing a semiconductor element according to claim 1, wherein the semiconductor element is a compound semiconductor element.   The method of manufacturing a semiconductor element according to claim 1, wherein the semiconductor element is a solar cell.   By using an etchant that does not erode the semiconductor substrate for etching the first intermediate layer, the substrate is used as a support substrate, and the semiconductor element layer is peeled off from the element in the epitaxial growth plane direction of the first intermediate layer, The manufacturing method of the semiconductor element in any one of Claims 1-3.   Etching the first intermediate layer using an etching solution that erodes the semiconductor substrate, eroding the substrate, laminating a support substrate on the epitaxial growth surface of the first intermediate layer, and peeling from the element in the substrate direction, The manufacturing method of the semiconductor element in any one of Claims 1-4.   6. A method of manufacturing a semiconductor device, comprising: forming a barrier layer that does not erode with an etching solution used for etching the intermediate layer according to claim 4 in a layer in contact with the intermediate layer.

Images