JPS6255963A - Gaas semiconductor device - Google Patents

Abstract

PURPOSE:To prevent a P-N junction from damaging due to heat generated in case of electric welding by forming a barrier metal layer between a P-type GaAs layer and a P-type electrode layer. CONSTITUTION:A P-type GaAs film 2 is epitaxially formed on an N-type GaAs substrate 1 by a conventional method, a reflection preventive film 4 is attached onto an AlGaAs film 3, and a window 9 is selectively opened. A TiN film 5 is coated as a barrier metal by a reactively sputtering method on the film 2. Thereafter, P-type electrodes and N-type electrodes 7 are attached as the conventional one. Even if a high welding voltage is applied in case of welding an interconnector 8 in this construction, the film 5 becomes the barrier for the film 2 to prevent the reaction with the P-type electrode (Ti/Ag, Ag/Zn) to prevent a P-N junction from damaging to perform the connection of sufficient strength, thereby improving the reliability.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] This invention relates to an electrode structure of a GaAs semiconductor device.

[Conventional technology]

FIG. 4 shows an example of a conventional GaAs semiconductor device.
The method for manufacturing an As solar cell is shown in the order of steps.

The conventional method will be explained below using this.

First, as shown in FIG. 4(a), an n-type GaAs substrate (
1) A I - G a A s with zinc added to the top surface
Al-G is grown by liquid phase epitaxial growth using melt.
Grow the a As layer (3). At the time of B, the added zinc diffuses into the n-type GaAs substrate (1) and becomes a P-type GaAs substrate (1).
AAs layer (2) is formed. Especially when used in space,
GaAs solar cells with strong radiation resistance are required, and P-type Ga
An As layer (2) (with a film thickness of about 0.5 μm is required).Next, as shown in Figure 4(b), an antireflection film (4) is deposited on the top surface of the AN-GaAs layer (3) by CVD. After forming the contact hole (9) by the method, the contact hole (9) is selectively formed by the photolithography and etching method.Next, as shown in FIG.
9) P-type electrode layer (T i /Ag, Ag-Zn, etc.)
6), A u G on the back side of the n-type GaAs substrate (1)
An n-type electrode layer (7) of Ni-Ag is formed. Next, a silver ink connector (8) is connected to the P-type electrode layer (6) by electric welding to form a module.

[Problem that the invention seeks to solve]

As shown in Figure 4, when a high welding voltage is applied when connecting the P-type electrode layer (6) and the ink connector (8) by electric welding, high heat is generated, and the material of the P-type electrode layer (6) This may damage the Pn junction 00). Also,
If the i* contact voltage of electric welding is lowered for fear of damaging the P-n junction α0), the P-type electrode layer (6) and the ink connector (8)
There is a problem that they do not bond. From the above,
The connection between the P-type electrode layer (6) and the interconnector (8) is as follows:
The range of optimal setting conditions for electric welding, such as welding voltage and welding voltage pulse width, is very narrow and requires careful consideration. In addition, there were problems with the applied voltage in conventional electric welding, such as oxidation of the tip of the welder during welding, and poor reproducibility of the optimal setting conditions.

[Purpose of the invention]

The present invention was made to solve the above-mentioned problems, and an object of the present invention is to obtain an ink connector having sufficient connection strength and a GaAs semiconductor device in which the Pn junction is not damaged.

[Means for solving problems]

The GaAs semiconductor device according to the present invention is made of P-type GaAs.
A thin film of TiN is provided between the layer (2) and the P-type electrode layer (6).

[For production]

In this invention, the thin film of TiN between the P-type GaAs layer (2) and the P-type electrode layer (6) is heated by heat generated during electric welding with a high welding voltage applied to the lower P-type electrode layer. Since there is no reaction with the Pn junction, damage to the Pn junction is prevented.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to the drawings. 1st
The figure is a top view of an embodiment of the present invention excluding the ink connector (8), FIG. This is the same state as in FIG. 4(b) of the conventional method. Figure 2 (b
) is a sectional view taken along the line Tub-4b' in FIG. 1(a), in which the interconnector (8) is welded. In the method of this embodiment, after the state shown in FIG. 2(a), as shown in FIG. 2(b), the P-type GaAs layer (
2) A TiN layer (5
), and then a P-type i'S pole layer (6) and an n-type electrode layer (7) are formed in the same manner as in the conventional method. The ink connector (8) is connected to the P-type electrode layer (6) for modularization.

By forming the TiN layer (5) between the P-type GaAs layer (2) and the P-type electrode layer (6), even if a high welding voltage is applied when welding the ink connector (8), the TiN
The layer (5) functions as a barrier metal with respect to the P-type GaAs layer (2), and the Pn junction 00) is no longer damaged. In the conventional case, the welding voltage was limited to 0.5KV, but due to the above-mentioned function of the TiN layer (5), it can be reduced to 0.55KV.
It can be increased up to KV. Furthermore, since a phantom welding voltage is applied during welding, a connection with sufficient strength can be achieved, and the reliability of the connection can be improved.

Note that since the TiN layer (5) has a high contact resistance, if it is provided on the grid electrode (6a), the conversion efficiency of the GaAs solar cell will decrease, so it cannot be provided on the entire upper part of the P-type electrode layer (6). Therefore, as shown in Fig. 1, there is a case where the TiN layer (5) is provided only in the part where the ink connector (8) is connected, and a case where the TiN layer (5) is provided only on the part where the ink connector (8) is connected, and a case where the TiN layer (5) is provided on the entire common electrode (6a) as shown in Fig. 3.
A case may be considered in which a layer (5) is provided.

〔Effect of the invention〕

As described above, according to the present invention, since the TiN layer is formed between the P-type electrode layer and the P-type Gaza layer in the common electrode section, it is possible to prevent the Pn junction from being damaged in the P-type electrode material. Therefore, as described above, since a high welding voltage can be applied during welding, a GaAs solar cell with high adhesive strength of the ink connector can be obtained. Moreover, this TiN layer is made of Ga
It should be applicable to GaAs semiconductor devices other than As solar cells.

[Brief explanation of drawings]

1 and 3 are a front view of a GaAs solar cell according to an embodiment of the present invention, and FIG. 2 is a sectional view showing the manufacturing process of a GaAs solar cell according to an embodiment of the present invention. (b
) is a sectional view of Hb-1'Ib' cotton in FIG. 1, and FIG. 4 is a sectional view showing the manufacturing process of a conventional GaAs solar cell. l if n-type GaAs substrate, 2 is P-type GaAs layer, 3
is Aj'-GaAs layer, 4ζ is anti-reflection film, 5 is TiN
6 is a P-type electrode layer, 6a is a grid electrode, 6bi is a common electrode, 7 is an N-type electrode layer, and 8 is an ink connector. In addition, in the figures, the same reference numerals indicate the same or corresponding parts.

Claims (1)

[Claims] A GaAs layer, a TiN layer formed on a selected region of the surface of the GaAs layer, an electrode layer formed on the surfaces of the GaAs layer and the TiN layer, and an electrode formed on the surface of the electrode layer on the TiN layer. A GaAs semiconductor device equipped with.