CN107680901A - The flexible compound substrate and manufacture method of a kind of semiconductor epitaxial - Google Patents

Abstract

The invention belongs to the field of semiconductors, and discloses a flexible composite substrate for semiconductor epitaxy and a manufacturing method. Take two polished silicon wafers with a thickness of 100 microns-1000 microns, and evaporate or sputter 0.1 microns-1000 microns on each polished surface. 5 micron metal aluminum, and then through the aluminum on the two silicon wafers bonded together for high-temperature bonding, the two silicon wafers are bonded together; during the bonding process, part of the aluminum and silicon form an alloy, and the silicon wafers The aluminum layer will also remain between them, and the thickness of the aluminum layer is less than or equal to 0.5 microns; one of the two silicon wafers bonded together is thinned and polished to a thickness of 1 micron to 10 microns to make a flexible substrate; the thin film of the flexible substrate With one side of the silicon wafer facing up, semiconductor thin film materials are epitaxially grown. The invention reduces the thermal adaptation between the silicon and the semiconductor film by making the silicon substrate into a flexible substrate, thus reducing the stress caused by the difference in expansion coefficient between the silicon and the semiconductor film.

Description

Flexible composite substrate for semiconductor epitaxy and manufacturing method thereof

technical field

The invention belongs to the field of semiconductors, in particular to a flexible composite substrate for semiconductor epitaxy and a manufacturing method.

Background technique

Semiconductor light-emitting devices have a wide range of uses, such as semiconductor light-emitting diodes, which can be applied to instrument working status indication, traffic lights, large-screen display, lighting and so on. In recent years, epitaxial AlGaInN and other thin films on silicon substrates have received great attention, but due to the difference in thermal expansion coefficient between silicon substrates and AlGaInN and other epitaxial layers, large thermal adaptation and lattice differences between them have caused crystal energy Mismatch, so the epitaxial AlGaInN on the silicon substrate is prone to cracks and it is difficult to improve the crystal quality.

To sum up, the problems existing in the prior art are: due to the difference in thermal expansion coefficient between the silicon substrate and the epitaxial layer such as AlGaInN, a large thermal adaptation is caused. Reduce the impact, so the epitaxial AlGaInN on the silicon substrate is prone to cracks, which cannot be avoided;

The flexible composite substrate for semiconductor epitaxy of the present invention can greatly relieve the thermal stress between the semiconductor material grown on the flexible substrate and the flexible substrate.

Contents of the invention

Aiming at the problems existing in the prior art, the invention provides a flexible composite substrate for semiconductor epitaxy and a manufacturing method.

The present invention is achieved in this way, a method for manufacturing a flexible composite substrate for semiconductor epitaxy, the flexible composite substrate for semiconductor epitaxy and the manufacturing method include the following steps:

Step 1. Take two silicon wafers with a thickness of 100 microns to 500 microns and polish them on one side. Evaporate or sputter 0.1 microns to 5 microns of aluminum on each polished surface, and then attach the two silicon wafers with the aluminum faces facing each other. Put them together for high-temperature bonding, bonding two silicon wafers together;

Step 2. Part of the aluminum and silicon form an alloy during the bonding process, and the aluminum layer will remain between the silicon wafers. The thickness of the aluminum layer is controlled to be less than or equal to 0.5 microns through annealing and other processes;

Step 3, thinning and polishing one of the two silicon wafers to a thickness of 1 micron to 10 micron to make a flexible substrate;

Step 4, epitaxially growing semiconductor with the thin silicon wafer of the flexible substrate facing upwards.

Further, the two silicon wafers are thick silicon wafers and thin silicon wafers; the thick silicon wafers of the flexible substrate may use solar grade silicon wafers, single crystal silicon wafers, gallium arsenide, indium phosphide, metal tungsten, molybdenum , tungsten-copper alloy, molybdenum-copper alloy, silicon-aluminum alloy, aluminum-silicon carbide alloy and other wafers; the selection principle is that its expansion coefficient matches that of the semiconductor material that needs epitaxial growth as much as possible.

Further, the thin silicon slice of the flexible substrate is located on the upper layer of the flexible substrate; the thin silicon slice of the flexible substrate or a single crystal thin slice of gallium arsenide, indium phosphide, gallium arsenide, aluminum gallium indium phosphide The selection principle is that its lattice constant matches the lattice constant of the semiconductor material that needs epitaxial growth as much as possible.

Further, before forming metal aluminum on one side of the upper thin silicon wafer, a layer of _sio2 or SiN is first grown as a barrier layer; the barrier metal Al is diffused to semiconductors such as the upper thin silicon wafer, and the upper thin silicon wafer of the flexible composite substrate is maintained. The crystal lattice of semiconductors is pure.

Another object of the present invention is to provide a kind of flexible composite substrate for semiconductor epitaxy, the upper layer of the flexible composite substrate for semiconductor epitaxy is a thin silicon wafer layer with surface polishing, the middle layer is an aluminum layer, and the lower layer is a thick silicon wafer layers; and are bonded together in turn.

Another object of the present invention is to provide an AlGaInN semiconductor material grown using the above-mentioned flexible composite substrate for semiconductor epitaxy.

Another object of the present invention is to provide a GaAs semiconductor material grown using the above-mentioned flexible composite substrate for semiconductor epitaxy.

Another object of the present invention is to provide an AlGaInP semiconductor material grown using the above-mentioned flexible composite substrate for semiconductor epitaxy.

Another object of the present invention is to provide an InP semiconductor material grown using the above-mentioned flexible composite substrate for semiconductor epitaxy.

Another object of the present invention is to provide a semiconductor material such as TeCdHg grown using the above-mentioned flexible composite substrate for semiconductor epitaxy.

The advantages and positive effects of the present invention are: the thermal adaptation between silicon and AlGaInN and other epitaxial films is reduced by making the silicon substrate into a flexible substrate, thus reducing the stress caused by the difference in expansion coefficient between silicon and AlGaInN , the main principle is: when using 1000-1400 degrees high temperature epitaxial growth semiconductor film on the general silicon substrate, the silicon substrate is also subjected to high temperature, at high temperature, the epitaxial wafer is flat, when the temperature is lowered, the grown semiconductor material The coefficient of thermal expansion of the epitaxial film is larger than that of the silicon wafer, and the epitaxial film will shrink, while the expansion coefficient of silicon is small, and the epitaxial film is subjected to tensile stress. When the tensile stress is large enough, the epitaxial film can only produce cracks to release the stress. When the substrate is used, before the temperature drops to the melting point of silicon-aluminum alloy (about 570 degrees), the upper silicon wafer of the flexible composite substrate seems to be floating on the liquid. The upper silicon wafer of the flexible composite substrate is very thin, and the thin silicon wafer and the epitaxial film Insufficient tensile stress generated by the thermal adaptation between the upper epitaxial growth of the semiconductor film torn, from the temperature of 1000 degrees to about 570 degrees, has avoided the thermal stress caused by the temperature of 430 degrees, when the temperature is lowered to below 570 degrees At this time, the epitaxial film is subjected to the tensile stress of the entire substrate, but the stress received at this time is only the stress caused by the drop from 570 degrees to room temperature, which is much smaller than the stress received from 1000 degrees to room temperature. If the thick silicon of the flexible composite substrate is one The material with the same expansion coefficient as the grown semiconductor is used on the side. For example, if the epitaxial material AlGaInN is grown, a tungsten-copper alloy with the same expansion coefficient is used, so that the thermal stress received is smaller, thus avoiding AlGaInN and other epitaxially grown semiconductor materials. Cracks and reduce epitaxy process complexity and improve crystal quality, thus improving chip stability, performance and life.

Description of drawings

1 is a flow chart of a method for manufacturing a flexible composite substrate for semiconductor epitaxy provided by an embodiment of the present invention;

Fig. 2 is a schematic structural view of a flexible composite substrate for semiconductor epitaxy provided by an embodiment of the present invention.

In the figure: 1, thin silicon layer; 2, aluminum layer; 3, thick silicon layer.

detailed description

In order to make the object, technical solution and advantages of the present invention more clear, the present invention will be further described in detail below in conjunction with the examples. It should be understood that the specific embodiments described here are only used to explain the present invention, not to limit the present invention.

As shown in Figure 1, the flexible composite substrate and manufacturing method for semiconductor epitaxy provided by the embodiment of the present invention include the following steps:

S101. Take two silicon wafers with a thickness of 300 microns to 500 microns polished on one side, evaporate or sputter metal aluminum of 0.1 microns to 2 microns on the polished surface of each film, and then bond the two silicon wafers with the aluminum surfaces facing each other. Carry out high-temperature bonding together to bond two silicon wafers together;

S102. Part of the aluminum and silicon form an alloy during the bonding process, and an aluminum layer remains between the silicon wafers. The thickness of the aluminum layer is less than or equal to 0.5 microns, and the thickness of the residual aluminum can be controlled by subsequent annealing;

S103, thinning and polishing one of the two silicon wafers to a thickness of 1 micron to 10 micron to make a flexible substrate;

S104 , performing epitaxial growth with the thin silicon wafer side of the flexible substrate facing up.

One side of the thick silicon wafer of the flexible substrate can be a wafer of solar grade silicon wafer, gallium arsenide, indium phosphide, metal tungsten, molybdenum, tungsten-copper alloy, molybdenum-copper alloy, silicon-aluminum alloy, aluminum-silicon carbide alloy, etc. , the selection principle is that its expansion coefficient matches that of the semiconductor material that needs epitaxial growth as much as possible; if the upper layer is a thin-layer silicon wafer, it must be a single crystal silicon wafer.

The thin silicon wafer of the flexible composite substrate can also be single-crystal thin slices of gallium arsenide, indium phosphide, gallium arsenide, aluminum gallium indium phosphide, and the selection principle is to satisfy its lattice constant and the semiconductor material that needs epitaxial growth The lattice constants are as consistent as possible.

Before sputtering or evaporating metal aluminum on one side of the upper thin silicon wafer of the flexible composite substrate, a layer of barrier layer such as sio ₂ , SiN, etc. can be grown first to prevent metal Al from diffusing to the upper thin silicon wafer and other semiconductors to maintain flexibility. The crystal lattice of semiconductors such as thin silicon wafers on the composite substrate is pure.

The flexible composite substrate can also grow GaAs, AlGaInP, InP, TeCdHg and other semiconductor materials.

During the epitaxial growth process, since aluminum and alloys are always in a melting state, the AlGaInN film is only affected by the upper thin silicon layer, so the stress is small and the crystal quality is improved. Since the eutectic point of silicon-aluminum solid solution is about 570 degrees, before the temperature drops to 570 degrees, AlGaInN is only subjected to the tensile stress of the upper silicon layer of a few microns. This tensile stress is not enough to crack AlGaInN. When the temperature drops from 570 degrees to room temperature , AlGaInN is subjected to the tensile stress of the entire flexible substrate, but the tensile stress of the AlGaInN epitaxial layer is completely different from 570 degrees to room temperature and from 1000 degrees to room temperature. The former has a smaller tensile stress on AlGaInN This greatly reduces the tensile stress on AlGaInN from the silicon substrate, reduces cracks, and improves crystal quality.

Fig. 2 is a schematic structural view of a flexible composite substrate for semiconductor epitaxy provided by an embodiment of the present invention. The upper layer of the flexible composite substrate for semiconductor epitaxy is a thin silicon layer 1, the middle layer is an aluminum layer 2, and the lower layer is a thick silicon layer 3; and are bonded together in sequence.

The present invention will be further described below in conjunction with positive effects.

The present invention uses flexible substrates to grow epitaxial thin films such as AlGaInN series and has the following advantages:

1. Because the present invention reduces the stress of the silicon wafer and the AlGaInN thin film, improves its crystal quality, naturally increases the device yield, performance and reliability, and reduces the production cost.

2 It is also possible to grow thick AlGaInN epitaxial films on flexible substrates, and then remove silicon by chemical etching to obtain thick AlGaInN films. Thick AlGaInN films can be used as homogeneous substrates, which is different from the existing thick AlGaInN films grown on sapphire with HVPE. Compared with the method of making homogeneous substrates with thin films, steps such as cutting and polishing are reduced, the difficulty of making homogeneous substrates is greatly reduced, and the cost is reduced.

3. Existing silicon substrate epitaxial AlGaInN thin films make HEMT devices, in which the AlGaInN thin films cannot grow thick, which makes the crystal quality not high, making it difficult to make high-quality HEMT devices, but using flexible substrates can easily grow thick AlGaInN thin films, Greatly improve the performance of electronic devices such as HEMT.

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements and improvements made within the spirit and principles of the present invention should be included in the protection of the present invention. within range.

Claims (10)

1. A method for manufacturing a flexible composite substrate for semiconductor epitaxy, characterized in that, the flexible composite substrate for semiconductor epitaxy and the method for manufacturing comprise the following steps: Step 1. Take two silicon wafers with a thickness of 100 microns to 500 microns and polish them on one side. Evaporate or sputter 0.1 microns to 5 microns of aluminum on each polished surface, and then attach the two silicon wafers with the aluminum faces facing each other. Put them together for high-temperature bonding, bonding two silicon wafers together; Step 2. Part of the aluminum and silicon form an alloy during the bonding process, and the aluminum layer will remain between the silicon wafers. The thickness of the aluminum layer is controlled to be less than or equal to 0.5 microns through the annealing process; Step 3, thinning and polishing one of the two silicon wafers to a thickness of 1 micron to 10 micron to make a flexible substrate; Step 4, epitaxially growing semiconductor with the thin silicon wafer of the flexible substrate facing upwards. 2. the method for manufacturing the flexible composite substrate used for semiconductor epitaxy as claimed in claim 1, is characterized in that, described two silicon slices are thick silicon slice and thin silicon slice; The thick silicon slice of described flexible substrate or adopt One of solar-grade silicon wafers, monocrystalline silicon wafers, gallium arsenide, indium phosphide, metal tungsten, molybdenum, tungsten-copper alloy, molybdenum-copper alloy, silicon-aluminum alloy, and aluminum-silicon carbide alloy. 3. The method for manufacturing a flexible composite substrate for semiconductor epitaxy as claimed in claim 2, wherein the thin silicon wafer of the flexible substrate is positioned on the upper layer of the flexible substrate; the thin silicon wafer or gallium arsenide , indium phosphide, gallium arsenide, aluminum gallium indium phosphide single crystal flakes. 4. The flexible composite substrate for semiconductor epitaxy according to claim 3, characterized in that, before forming metal aluminum on one side of the upper thin silicon wafer, a layer of _SiO2 or SiN barrier layer is first grown. 5. the flexible composite substrate of a kind of semiconductor epitaxy that provides as claimed in claim 1 is characterized in that, the upper layer of the flexible composite substrate of described semiconductor epitaxy is a thin silicon wafer layer, and middle layer is aluminum layer, and lower layer is Thick silicon wafer layers; and bonded together in sequence. 6. An AlGaInN semiconductor material grown by utilizing the flexible composite substrate for semiconductor epitaxy according to claim 5. 7. A GaAs semiconductor material grown by using the flexible composite substrate for semiconductor epitaxy according to claim 5. 8. An AlGaInP semiconductor material grown by utilizing the flexible composite substrate for semiconductor epitaxy according to claim 5. 9. An InP semiconductor material grown by utilizing the flexible composite substrate for semiconductor epitaxy according to claim 5. 10. A TeCdHg semiconductor material grown by utilizing the flexible composite substrate for semiconductor epitaxy according to claim 5.