JPH0353569A - Semiconductor device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a semiconductor device having a highly reliable and high quality semiconductor crystal structure. [Prior Art] FIG. 3 is a cross-sectional view of a conventional semiconductor wafer having a GaAs thin film on a St semiconductor crystal substrate. In this figure, 1 is a semiconductor crystal substrate such as a Si crystal substrate having a thickness of 200 μm (thermal expansion coefficient 2.4 x 1 0-'/t), 2
is a GaAs layer (thermal expansion coefficient 8.9xlO-'/t) having a thickness of 5 μm formed on this semiconductor crystal substrate 1.
It is.

FIG. 4 is a sectional view showing a semiconductor device having a charge conversion function. In this figure, reference numeral 1.2 is the same as in FIG. 3, and the GaAs layer 2 is formed of two layers having different conductivity, for example, an n-type GaAs layer 21 and a p-type GaAs layer 22 which is an active layer.

Electrodes 5.6 are formed on the upper surface of the p-type GaAs layer 22, which is the active layer, and on the back surface of the semiconductor crystal substrate 1. Light can be generated by passing a current in the forward direction across both ends of this electrode 5.6.

(Problem to be Solved by the Invention) On the semiconductor crystal substrate 1 having a thermal expansion coefficient of approximately 2.4×10−′/° C. as described above, a thermal expansion coefficient of 6.9×10−′/° C.
In the above-mentioned conventional semiconductor crystal wafer including the GaAs layer 2 of t, stress is applied to the semiconductor crystal wafer due to the difference in thermal expansion coefficients, causing warping. For example, on a semiconductor crystal substrate 1 with a size of 50 mm x 50 mm and a thickness of 100 μm, 5
When a GaAs semiconductor layer with a thickness of μm is formed,
There were problems such as a maximum warpage of about 2.7 ma+, a large stress being applied to the GaAs crystal, and cracks occurring.

This invention was made to solve these problems, and it eliminates warpage of semiconductor crystal wafers and reduces stress, prevents cracks from occurring in the semiconductor layer formed on the semiconductor crystal substrate, and improves quality. The objective is to obtain a highly reliable semiconductor device.

[Means to solve the problem]

A semiconductor device according to the present invention includes a semiconductor layer or a metal layer having a coefficient of thermal expansion that is the same as or close to that of the semiconductor crystal layer and a thickness that is the same as or close to that of the semiconductor crystal layer. It was established in

(Function) In the present invention, a semiconductor layer or metal having a coefficient of thermal expansion that is the same as or close to that of the formed semiconductor crystal layer and a thickness that is the same or close to that of the semiconductor crystal layer is formed on the semiconductor crystal substrate. Since the layer is formed on the back surface of the semiconductor crystal substrate, occurrence of thermal stress and warpage due to differences in thermal expansion coefficients can be suppressed.

〔Example〕

FIG. 1 shows a cross-sectional view of a semiconductor crystal wafer according to the invention. In this figure, 1 is a semiconductor crystal substrate such as an St single crystal substrate having a thickness of 200 μm, and 2 is a semiconductor crystal substrate such as a St single crystal substrate having a thickness of 200 μm, and 2 is a semiconductor crystal substrate using an organic metal epitaxial method (Metal Org-anic Chem
ical Vapor Deposition; M O
This is a GaAs layer formed on the semiconductor crystal substrate 1 by C V D ), liquid phase epitaxial method, gas phase epitaxial method, or the like. 3 is the semiconductor crystal substrate 1
This is a Ge layer having the same or similar thermal expansion coefficient and thickness as the GaAs layer 2 formed on the back surface of the . A Ge layer 3 having the same or similar thermal expansion coefficient and thickness as the GaAs layer 2 is formed on the back surface of the semiconductor crystal substrate 1 by vacuum evaporation, germane (GeH4) thermal decomposition method, or G
It is formed by the hydrogen reduction method of halogen compounds (Electrochemical Society of Japan, Electronic Materials Committee, Semiconductor Materials). next,
A reaction between trimethyl gallium and arsine Ga (CH3) , + A. H,→GaAs + 3
A GaAs layer 2 of 5 μm thickness is formed at a growth temperature of about 750° C. by MOCVD using CH4. In the conventional example, when a GaAs layer 2 of 3 μm or more is formed on a semiconductor crystal substrate 1, the difference in thermal expansion coefficient between GaAs and Si (GaAs:
6.9x 1 0-”/'e, S i : 2.6X
10-'/'e), a large thermal stress is generated in the GaAs layer 2, causing warping. Although there was a problem that cranking occurred, the Ge layer 3 formed on the back surface of the semiconductor crystal substrate 1 according to invention C has a thermal expansion coefficient of 5.9X10-''6/-c, which is close to GaAs, and the semiconductor crystal substrate The warpage of the GaAs layer 2 on the semiconductor crystal substrate 1 is greatly reduced and becomes almost flat.
Cracks in the upper GaAs layer 2 can be prevented, and a high quality and highly reliable semiconductor crystal wafer can be obtained.

FIG. 2 is a sectional view of a semiconductor device showing an embodiment of the present invention, in which a GaAs pn using the semiconductor crystal wafer of FIG. 1 is shown.
1 shows a cross-sectional structure of a light emitting diode having a junction.

In FIG. 2, the semiconductor crystal substrate 1 is an n-type (100)
It has a thickness of 200 μm and has a plane orientation. The GaAs layer 2 has a thickness of 5 μm and is formed by MOCVD, for example. Also, the n-type impurity concentration is 1 x 1
0"cm-3. 4 is the amount of zinc (
This is a p-GaAs diffusion layer with a diffusion depth of 1.5 μm formed by sealing diffusion of Zn). 3 is the above n
- a Ge layer having the same thickness as the GaAs layer 2; 5.
6 indicates an electrode.

In the semiconductor device having the function of a light emitting diode formed on the semiconductor crystal substrate 1 according to the present invention, since the semiconductor crystal wafer is flat without warping, variations in brightness within the wafer of the light emitting diode are reduced and high A high quality semiconductor device can be obtained. Furthermore, cracks during the process due to warping are eliminated, and a highly reliable semiconductor device can be obtained.

Note that in the above embodiment, Ge is deposited on the back surface of the semiconductor crystal substrate 1.
A light emitting diode has been described as an example of a semiconductor crystal wafer having a GaAs layer 2 on a semiconductor crystal substrate 1 having a layer 3 and a semiconductor device thereof. electronic devices and solar cells. In addition to light-receiving and light-emitting diodes such as laser diodes, GaAs IC
and optical integrated circuits.

In addition, although the case where Ge is used as the back surface material of the semiconductor crystal substrate 1 has been described, instead of Ge, a metal having a coefficient of thermal expansion similar to that of the GaAS layer 2, such as tungsten, is used. carbon. It may also be a metal such as tantalum. Of course, G with the same thickness
Of course, adding an aAs layer is also effective.

Furthermore, Ga is used as a semiconductor crystal layer on the semiconductor crystal substrate 1.
Although the case of forming the As layer 2 has been described, compound semiconductors other than GaAs such as InP, GaP, or Ga
As mixed crystal compound semiconductor. GaAs, GaAsP
Needless to say, this can also be applied to other matters.

〔Effect of the invention〕

As explained above, the present invention provides a semiconductor layer or a metal layer having the same or similar thermal expansion coefficient as the semiconductor crystal layer and the same or similar thickness as the semiconductor crystal layer on the back surface of the semiconductor crystal substrate. This has the effect of eliminating warping of the semiconductor crystal wafer, preventing cracks in the semiconductor crystal layer formed on the semiconductor crystal substrate, and obtaining a high quality and highly reliable semiconductor device.

[Brief explanation of drawings]

1 is a cross-sectional view of a semiconductor crystal wafer to which the present invention is applied, FIG. 2 is a cross-sectional view showing an embodiment of a semiconductor device of the present invention using the semiconductor crystal wafer of FIG. 1, and FIG. Fourth
The figures show cross-sectional views of a conventional semiconductor crystal wafer and a conventional semiconductor device, respectively. In the figure, 1 is a semiconductor crystal substrate, 2 is a GaAs layer, and 3 is a semiconductor crystal substrate.
is a Ge layer, 4 is a diffusion layer, and 5.6 is an electrode. Note that the same reference numerals in each figure indicate the same or corresponding parts.

Claims (1)

[Claims] In a semiconductor device using a semiconductor crystal wafer having, on a semiconductor crystal substrate, a semiconductor crystal layer having a coefficient of thermal expansion different from that of the semiconductor crystal substrate, having a coefficient of thermal expansion that is the same as or close to that of the semiconductor crystal layer of the semiconductor crystal wafer, A semiconductor device further comprising: a semiconductor layer or a metal layer having a thickness the same as or close to that of the semiconductor crystal layer, provided on the back surface of the semiconductor crystal substrate.