JPS62214627A - Liquid phase epitaxial growth process - Google Patents

Abstract

PURPOSE:To prevent any defective crystal such as pits from occuring on an epitaxial crystalline layer by a method wherein a dummy wafer is melted in a melting solution and then the composition of melting solution is changed to be bonded on a substrate while compound semiconductor crystals with differ ent compositions are formed into multilayered structure. CONSTITUTION:A dummy wafer 15 is brought into contact with melting solution 16 while a heating furnace is heated up to 490 deg.C to melt the constituent of dummy wafer 15 in the melting solution 16. Thus, the composition of melting solution 16 is shifted from a point A to another point B also to the part near the point of intersection of a liquid line 32 at 500 deg.C and a solid phase line 42 at X=0.3 changing to another melting solution 18 with the value of x=0.3 at that time equivalent to Hg1-xCdxTe. Next, an ampule 17 is further turned by 180 degrees in the arrow g direction while cooling down the heating furnace. Then, the substrate 13 is brought into contact with the melting solution 18 with Hg1-xCdxTe at x=0.3 to epitaxially grow a crystalline layer with Hg1-xCdxTe at x=0.3 as a crystalline layer of the second layer. Through these procedures, the crystalline layers can be formed continuously into multilayered structure by simple process.

Description

[Detailed Description of the Invention] [Summary] A tilted liquid phase epitaxial growth method in which compound semiconductor crystal layers with different compositions are stacked in a multilayer structure on a substrate, for example, mercury with different compositions on a cadmium tellurium (CdTe) substrate.・Cadmium tellurium (Hg +-x C
When stacking compound semiconductor crystal layers of d After melting in a melt for forming a compound semiconductor crystal layer by changing the temperature of the melt and depositing the melt on a substrate with the composition of the melt changed,
By cooling, compound semiconductor crystals with different compositions are formed in a multilayer structure.

[Industrial application field]

The present invention relates to a tilted liquid phase epitaxial growth method, and particularly to a liquid phase epitaxial growth method for forming compound semiconductor crystal layers having different compositions in a multilayer structure on a substrate.

To form photoelectric conversion devices such as infrared sensing elements, mercury, cadmium,
A material in which a compound semiconductor crystal of tellurium (Hg + -XCd xT e ) is epitaxially grown is used.

By the way, in order to change the characteristics of the formed sensing element (1), Hg with different X values is placed on the CdTe substrate.
It is desired to epitaxially grow a +-xCdxTe crystal layer into a multilayer structure, and in that case, there is a need for a liquid phase epitaxial growth method that is simple and prevents crystal defects from occurring in the formed epitaxial crystal layer. There is.

[Conventional technology]

When forming such a crystal layer of Hg +-x Cd x Te into a multilayer structure by varying the X value, the above-mentioned Hg
Since mercury in g + -x Cd FIG. 4 is an explanatory diagram of a conventional liquid phase epitaxial growth apparatus. As shown in the figure, a pair of substrate setting jigs 2 holding a CdTe substrate 1 are placed under the substrate 1 to form Hg, -, which is to be formed on the substrate 1. The xCdxTe crystal layer forming material 4 is housed inside a quartz ampoule 3, and after the inside of this quartz ampoule 3 is evacuated, its end a is sealed.

After introducing such a liquid phase epitaxial device into a heating furnace, the Hg + CdxTe crystal layer forming material 4 is melted,
After rotating the device 180 degrees as shown by the arrow, the melt of the forming material 4 is attached to the substrate 1, and the temperature of the heating furnace is lowered to lower the temperature of the melt, and Hg+ is deposited on the substrate. −
A crystal layer of xCdXTe was formed.

(Problems to be Solved by the Invention) By the way, when forming a multilayer structure of crystal layers with varying X values on the substrate 1 on which such a crystal layer of Hg+-xCdxTe is formed, the quartz ampoule 3 is It is necessary to destroy and take out the substrate, in which case the substrate 1 is contaminated by the atmosphere and therefore due to this contamination the X that is subsequently formed
A problem arises in that crystal defects such as bits occur in the crystal layer of Hg + -xCd xT e whose value is varied.

In addition, the quartz ampoule 3 must be destroyed one by one, and there is a problem in that the manufacturing cost is too high.

The present invention eliminates the above-mentioned problems and provides a liquid phase epitaxial growth method in which crystal defects such as pits are not generated in a multilayered epitaxial crystal layer formed by a simple method.

[Means for solving problems]

In the liquid phase epitaxial growth method of the present invention, a dummy wafer 15 made of a material 16 that forms a melt is placed on the back side of a substrate 13, and the dummy wafer 15 is dissolved in a melt whose temperature is changed to form a melt. The method is characterized in that the composition is varied and the melt with the varied composition is deposited on the substrate 13 to form compound semiconductor crystals with different compositions in a multilayer structure on the base Jfflla.

[Effect]

In the liquid phase epitaxial growth method of the present invention, a dummy wafer 15 of a compound semiconductor constituting a semiconductor crystal layer to be formed on the substrate is provided on the back side of the substrate 13, and this dummy wafer 15 is melted in a melt of a material 16 for epitaxial growth. By changing the composition of the melt, compound semiconductor crystal layers with different compositions can be easily formed into a multilayer structure on the substrate 1.
Epitaxial growth is performed on 3.

〔Example〕

Hereinafter, one embodiment of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a cross-sectional view of an apparatus used in the method of the present invention. As shown in FIG.
12, an epitaxial growth substrate 13 made of CdTe and a quartz plate 14 are sandwiched between them, and on the back side of the substrate 13, a C
A dummy wafer 15 made of dTe is installed, and a material 16 of Hg +-x Cd xTe (x=0.2) to be epitaxially grown on the substrate is placed below the dTe wafer 15, and these are placed in a quartz ampoule 17. After being inserted into the chamber, it is evacuated and one end of it is sealed.

Here, the temperature of the heating furnace was raised to 500°C, and the Hg
+−x Cd XT e material 16 is melted. This state is shown in FIG. 2(a).

In the figure, 16 is a molten Hg + -x Cd X Te material, 13 is a CdTe substrate, 14 is a quartz plate, and 15 is a dummy wafer.

Next, the temperature of the heating furnace is lowered from this state, and melt processing 6 is carried out.
temperature is lowered to 475°C. Then, the melt 16 exists at the intersection A of the liquidus line 3I at a temperature of 475°C and the solidus line 41 at a χ value of 0.2 in the phase diagram of Cd and Te shown in FIG. .

At this time, the state of FIG. 2(a) is changed to 18 as shown by arrow e.
Rotate the substrate 13 by 0 degrees to obtain the state shown in FIG.
A crystal layer of g + -x Cd X Te is formed as a first epitaxial layer.

Next, after forming the first epitaxial layer, the second epitaxial layer is formed.
As shown in Figure (C1), from the state of Figure 2 ('b), as shown by the arrow f, rotate the melt 1 as described above.
6, the dummy wafer 15 is brought into contact with the furnace, and the temperature of the heating furnace is set to 49.
The temperature is raised to 0° C., and the components of the dummy wafer 15 are melted into the melt 16.

Then, the composition of this melt 16 is determined from the composition at point A in FIG.
Moving to the composition of the point, the liquidus line 32 at 500℃ and X-0,3
, and the melt at that time becomes a melt 18 of Hg+-xcdXTe with a value of 0.3.

Next, while lowering the temperature of the heating furnace, the ampoule 17 is further rotated by 180 degrees as shown by the arrow g to perform the second rI!
The state is J(d). And x −0,3 on the substrate 13
A melt 18 of Hg +-x Cd XT e of x = 0.3 is brought into contact with the substrate.
A crystal layer of Te is epitaxially grown as a second crystal layer.

In this way, there is no need to take each substrate out to the outside and change the composition of the melt in the ampoule using a simple method.
Cd X Te crystal layers can be continuously formed into a multilayer structure.

In addition to the embodiments described above, for example, a crystal layer of Hg+-xcdx7e with x = 0.3 is formed on a CdTe substrate as a first layer, and a Hg
+-x When forming crystal layers of Cd X Te continuously into a multilayer structure, the initial melt composition is x-
A melt of 0.3 Hg+A CdxTe is used, and the temperature of the heating furnace is set to 475°C.

In this way, the x of the first layer is
A crystal layer of Hg+-xCdxTe of =0.3 can be formed.

Next, using a Hg Te crystal as a dummy wafer, the temperature of the heating furnace was raised to 485°C, and the composition of the HgTe dummy wafer was changed to Hg r-x Cd XT with x = 0.3.
By dissolving it in the melt of e, the composition of the melt becomes the state shown at point D in Figure 3, and Hg + - x C of X = 0.2
A melt of d X T e is obtained. By bringing the substrate into contact with this melt, a crystal layer of Hg+-xCdxTe with X=0.2 is formed as a second epitaxial layer.

In Fig. 3, 51 indicates the curve connecting the eutectic point of Hg and CdO, 33 indicates the liquidus line at 450°C, and 34 indicates the curve at 525°C.
The liquidus line at . Further, 43 indicates a solidus line for X=0.4, 44 indicates a solidus line for x=0.5, and 45 indicates a solidus line for x==o, e.

Also, the horizontal axis in Figure 3 is Hg +-x Cd XT 13
It shows the atomic fraction of Cd in the crystal, and the vertical axis shows the atomic fraction of Ifg.

〔Effect of the invention〕

As described above, according to the method of the present invention, an epitaxial layer of a compound semiconductor having a varied composition can be easily formed in a multilayer structure on a substrate, and the method of the present invention can be used to produce infrared sensing elements, etc. is large.

[Brief explanation of drawings]

Figure 1 is a sectional view of the apparatus used in the method of the present invention, Figure 2 (
Figures a) to 2(d) are explanatory diagrams showing the steps of the method of the present invention, Figure 3 is a phase diagram of Hg and Cd used in the method of the present invention, and Figure 4 is a conventional liquid phase epitaxial growth method. FIG. In the figure, 11.12 is a substrate installation jig, 13 is a substrate, 14 is a quartz plate, 15 is a dummy wafer, and 16 is Hg)-X Cd x
T e (x=0.2) material, 17 is ampoule, 18 is Hg l-x Cd xT a (x=0.3) material, 3
1, 32.33.34 is liquidus, 41.42.43.4
4.45 is a solidus line, and 51 is a curve connecting eutectic points. (X=0.2) For the rust brightening method - Roto bag L/) New button diagram Figure 1 Hg+-x cd xTe (X=0.2)/):AW
& Selection 421 Figure 2 (Q) Group [Hql-xcd xTe(X=0.2)t#Mti
J to m. Fig. 2 (b) cd X Te (Xc-
02) tJ fishing monument m2 Figure rc) fi Hg l-x cd xTe (Xc-0,3)
tr, %1is1M-rygl<aEUFigure 2 (d)

Claims (1)

[Claims] A compound semiconductor substrate (13) was sandwiched between a pair of substrate installation jigs (11, 12), and a melt of a compound semiconductor crystal material (16) to be formed on the substrate was provided at the bottom of the substrate (13). A method for growing a compound semiconductor crystal layer on the substrate (13) by rotating the ampoule (17) and depositing the melt on the substrate (13), cooling the melt and growing a compound semiconductor crystal layer on the substrate (13). A dummy wafer (15) made of a material (16) that forms a melt is placed on the back side of the wafer 13), and the dummy wafer (15) is brought into contact with the melt at a changed temperature and melted. Liquid phase epitaxial growth characterized by varying the composition of the melt and depositing the melt with the varied composition on the substrate (13) to form compound semiconductor crystals with different compositions in a multilayer structure on the substrate (13). Method.