JPS5816525A - Liquid phase epitaxial growth - Google Patents

Abstract

PURPOSE:To eliminate various bad effects during crystal growth by using a sliding board and making in advance the edge portion and its adjacent area of a crystal substrate thinner than the substrate's central portion. CONSTITUTION:In the multi-layer liquid phase epitaxial growth method using a sliding board the thickness of the edge portion and its adjacent area of a crystal growth substrate 4 coming in contact with a crystal growth solution is made thinner than the central portion of the substrate 4. For instance, the step difference of the substrate 4 at (a) is approx. 100mum, the taper hight of the substrate 4 at (b) is -100mum, and both substrates are approx. 150mum in length. This constitution can restrict the hight of an upheaval due to abnormal growth below the hight of the central portion of the substrate 4, thereby eliminating bad effects during crystal growth and when a grown crystal is processed.

Description

[Detailed description of the invention] The present invention relates to a method C2 for liquid phase epitaphthalmic growth.

In the liquid phase epitaxial growth method using a sliding hole, the flatness of the grown crystal after growth and during the growth process is an important issue.

Tsutomu liquid phase epitaxial growth C2 is shown in FIG. 1 and is carried out using a flat sliding boat. In the figure, numeral 1 denotes a solution container for storing 61 solutions, and 2 denotes a slider having a recess for accommodating 8!4V. If the inside of this sliding boat has a flat temperature distribution, the grown crystals that have passed through the first solution and the second solution will be located at the center of the substrate as shown in the cross-sectional view of the substrate shown in Figure 2. A product with a difference in thickness between the part and the end can be obtained. When there are 6-7 pieces of this solution, the substrate that comes out after passing through it will have a thickness difference of ~10 times depending on the location 62 (as shown in BL). The reason why the growth layer grows thicker can be thought of by a model as shown in Figure 3 (enlarged view of the part in Figure 1). As the cooling progresses, the liquid becomes supersaturated, and the fist is considered to precipitate to the 11 points at the shortest distance.
If we consider that it will precipitate into lotus, it will grow thickly to point b1.

In the slide boat that is normally used, crystal precipitation at point b1 occurs in many layers, so as mentioned above (
; A difference in thickness of ~1O times occurs.

This abnormal growth causes various problems in the crystal growth process and in the processing of the growth substrate.To briefly explain the former case, crystal growth is normally carried out using a sliding boat as shown in the first factor. During and after crystal growth C:
In order to avoid damaging the surface of the substrate when the substrate slides, a constant distance of 4 is provided between the substrate and the guide section. Ideally, the lower limit of this interval would be just the thickness of the crystal growth, but experimentally it has been found that the total distance required for no scratches is ~5
It is ~60 when performing crystal growth.

Further, in the case of multilayer crystal growth, a phenomenon in which the nth solution is brought into the (n+1)th solution occurs, so the upper limit is close to the lower limit. Here, when abnormal growth as described above occurs, the clearance of the part where abnormal growth has occurred is substantially reduced, and it is scraped by C; bow) during sliding, contaminating the substrate surface or causing carbon in the guide section. Do not cause any damage such as scraping it off. Slide surface I: On the other hand, when the guide surface is not fixed, the guide surface is pushed up and the nth solution is brought into the n+1th solution tank, so-called carry-over occurs. This is especially true for quartet crystal members.

Next 6: In the latter case, the abnormal growth causes the edges to bulge out from the center, so if you try to process the grown crystal as it is, it will cause cracks in the process of using a tight-adhesive I-frame alignment device, etc. The present invention was made in view of the above-mentioned deficiencies, and it prevents the harmful effects of abnormal growth! Crystal growth substrate! This method provides a method for removing the particles by processing them in advance.

The present invention eliminates various disadvantages during IFV during crystal growth by making the edge of the substrate crystal or the adjacent area (i.e., the area where abnormal growth is likely to occur) thinner than the center of the substrate. This is a growth method that can eliminate problems in processing crystal substrates.

Hereinafter, embodiments of the present invention will be explained using the inner surface.

The cross section of the crystal substrate used in the present invention is shown in Figure 4 (a1%lb
The growth boat used, shown in FIG. 1, is similar to that shown in FIG. The level difference of the substrate used in IB+ in Figure 4 is approximately 100μ, (the height of the taber of the substrate used in t+1 ~
10°0 voice, both lal and (bl) are approximately 150μ in length.
It is. Crystal substrate: uses a GaAs substrate crystal,
~4 layers of GaAe, GaAtAs were prepared by equilibrium cooling method at a cooling rate of 0.21@g/win from a holding temperature of 800°C.
Crystal growth was performed. The thickness of each layer was about 1 μm, and a total of about 4 μm of crystal growth was performed. Figure tJ & 5 - The state after growth is shown for each substrate. As can be seen from this, the bulge due to abnormal growth is suppressed to a level lower than the height of the center portion of the substrate, so that it does not cause any adverse effects during crystal growth and processing of the grown crystal.

By making the edge portions of the substrate lower than the center portion as described above, it is possible to prevent harmful effects caused by abnormal growth. It goes without saying that the height between the end portion and the center portion may be changed depending on the thickness and number of growth layers, and it goes without saying that the shape may also be other than those listed.

[Brief explanation of drawings]

FIG. 3 is a cross-sectional view of a state in which liquid-phase epitaxy growth is performed on a substrate using a $1 growth apparatus, and FIG. 3 is a cross-sectional view when conventional problem length growth is performed. l: Solution container 2; Slider 3; Abnormal growth part 4: Substrate 6; Solution (7317) Agent: Noriyuki Chika, patent attorney (and 1 others)
name) Figure 1 (ku) tl:,) Figure 3 Figure 4 Figure 5

Claims (1)

[Claims] In the multilayer liquid phase Evita #7 growth method using a sliding boat, the edges of the crystal growth substrate that are in contact with the crystal growth solution and the areas near the edges are thinner than the center of the crystal substrate. What it does: A method for growing liquid-phase shrimp.