JPS6398120A - Crystal growth method - Google Patents

Abstract

PURPOSE:To substantially eliminate the warpage of a substrate thereby to obtain a preferable crystal by forming a stripelike insulating film on the substrate, and selectively forming an epitaxial layer on the substrate except the insulating film forming region. CONSTITUTION:When a GaAs epitaxial layer 3 is grown by a vapor growing method, such as an MBE or an MOVPE method, etc. on a wafer 1, a GaAs polycrystal 4 is deposited on an SiO2 film 2 of latticelike stripe. At this time the warpage of a substrate is substantially alleviated to form a preferable crystal. Then, the layer 3 is selectively coated by a photolithography method with a photoresist 5, the crystal 4 and the film 2 are etched to allow the layer 3 to remain on the Si substrate 1 to cumplete the process.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention applies to semiconductor substrates such as Si single crystals, which are coated with 1[-V group compound semiconductors such as GaAs and InP, etc., which have different coefficients of thermal expansion, and U-■ such as ZnS and Zn5e. The present invention relates to a crystal growth method for epitaxially growing a group compound semiconductor single crystal.

BACKGROUND OF THE INVENTION In recent years, research and development have been actively conducted on techniques for epitaxially growing I[-V group compound semiconductors such as GaAs on SL single crystals. This is because Si is an IC.

As a substrate material for electric devices such as LSI, GaAs
Compound semiconductors such as these are used as light source materials for light emitting diodes, semiconductor lasers, etc., but if a light source is monolithically integrated on a Si substrate incorporating an IC, it is very promising as an optoelectronic integrated circuit (○EIC). It's coming. On the other hand, since semiconductor lasers are operated by high current injection and generate a large amount of heat, St wafers with good thermal conductivity are normally used as cooling mounts for semiconductor lasers. Improvements in the temperature characteristics of the laser can also be expected.゛Also, the substrate cost is cheaper for StO.

Usually, the molecular beam epitaxy method (
MBE) and metal organic vapor phase epitaxy (MOVPE). The growth temperature is approximately 500°C.

However, when cooled to room salt after epitaxial growth, slip dislocation occurs in the Ga As shrimp layer, causing cracks and peeling, which adversely affects the quality of the shrimp layer.

The reason is mainly that the thermal expansion coefficients of Si and Ga As are significantly different (linear expansion coefficient St: 2.5X10
-6/K, GaAs: 6.0X10-6/K)
Even if the Si wafer and GaAs epitaxial layer grow flat during growth, the wafer warps due to the difference in their thermal expansion coefficients at room temperature, adding strain to the shrimp layer and causing defects. FIGS. 5 and 6 show the state of the wafer during growth and the schematic diagram of the wafer at room temperature after growth. 1 indicates a Si substrate, and 2 indicates a GaAs epitaxial layer.

Problems to be Solved by the Invention As mentioned above, in the conventional epitaxial growth of GaAs on a Si substrate, warpage occurs in the substrate wafer due to the difference in thermal expansion coefficient between SL and GaAs, resulting in GaAs
Problems have arisen in that strain is applied to the epitaxial layer, causing slip dislocations to occur and defects such as cracks and peeling to occur. Therefore, the present invention provides a growth method for the purpose of alleviating warpage of a substrate wafer.

Means for Solving the Problems In order to alleviate the above-mentioned problem of wafer warpage, the present invention forms a striped insulating film on a substrate, and forms a striped insulating film on the exposed substrate surface outside the insulating film forming area. This method selectively forms an epitaxial layer.

Function: If an epitaxial layer is selectively formed on a substrate as described above, the thermal stress generated between the substrate and the epitaxial layer due to the difference in thermal expansion coefficients is interrupted by the insulating film and becomes intermittent, spreading over the entire wafer. No continuous thermal stress is applied.

Therefore, warpage of the wafer after growth is alleviated, and defects occurring in the epitaxial layer are reduced.

Examples Examples of the present invention will be shown below. FIG. 1 shows a Si (silicon) wafer on which a striped insulating film of the present invention is formed. 1 shows a 3-inch Si wafer, and 2 shows a Si02 thermal oxide film with lattice-like stripes. FIG. 2 shows a wafer cross-section after a GaAs epitaxial layer has been grown on the wafer of FIG. 3 is a GaAs epitaxial layer, and 4 is a GaAs polycrystalline layer deposited on the Sio2 film. Here, the stripe width of the SiO2 film 2 is 5■
, the thickness is 1 μm, and the thickness of the GaAg epitaxial layer is 1 μm.
It is μm. The GaAs layer was grown using a vapor phase growth method such as MBE or MOVPE. Therefore, GaAs polycrystal 4 was deposited on S 102 film 2. At that time, the warpage of the substrate is almost alleviated and good crystals are formed.

Next, as shown in FIG. 3, a photoresist 6 is selectively coated on the GaAs 8-layer pittaxial layer 3 by the photophosphorography method, and the GaAs polycrystal 4 and the S102 oxide film 2 are coated. As shown in FIG. 4, a Ga Ats epitaxial layer 3 is formed on the Si substrate 1 by etching.
and complete the process. Here, the insulating film is Si
Although O2 was used, it goes without saying that an insulating film such as a Sl 3 N 4 film or a carbon film may also be used. Also, G a A
In addition to s, other ■-■ group compound semiconductors such as InP and ■-
The present invention is also applicable to group (2) compound semiconductors.

Effects of the Invention As described above, if a striped insulating film is formed on a Si substrate and a GaAs epitaxial layer is formed in a region other than the insulating film region, there is almost no warping of the substrate and good crystals are formed. can get. Further, if the insulating film is selectively removed, even more effects can be obtained. Furthermore, by using the present invention, a thin shrimp layer can be obtained even on large diameter wafers (6 inches, 8 inches, etc.), which is difficult to achieve with GaAs substrates.

[Brief explanation of the drawing]

FIG. 1 shows Si in a crystal growth method according to an embodiment of the present invention.
FIG. 2 is a plan view showing the 3102 insulating film pattern on the substrate; FIG. 2 is a cross-sectional view of the GaAs layer deposited on the substrate;
The figure is a cross-sectional view explaining the process of removing the GaAs polycrystal and the S102 insulating film, and FIG.
A cross-sectional view showing the final step of growing an As single crystal film, FIG. S, and FIG. 6 are cross-sectional views for explaining a conventional crystal growth method. 1... Si substrate, 2... Insulating film, 3...
...G a As single crystal film. Name of agent: Patent attorney Toshio Nakao and one other person
3 to the board 2---5LOz pus Fig. 1 f -, St,, N@ 4- and 4s Omari force 1K f-, SM board Fig. 5 Fig. 6

Claims (2)

[Claims] (1) When epitaxially growing a semiconductor single crystal having a coefficient of thermal expansion different from that of the substrate on a semiconductor substrate, a striped insulating film is formed on the substrate, and a striped insulating film is formed on the exposed surface of the substrate in the region where the insulating film is formed. A crystal growth method comprising epitaxially growing the semiconductor single crystal. (2) The crystal growth method according to claim 1, wherein the semiconductor substrate is silicon and the semiconductor crystal is a compound semiconductor.