JPH0344967A - Manufacture of 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 [Summary] The present invention relates to a method of manufacturing a semiconductor device, and particularly to a method of manufacturing a semiconductor device including an InP Schottky junction.

The purpose of this study is to develop a method for effectively realizing InP Schottky junctions.

After forming an epitaxial atomic layer of GaAs of one conductivity type on an InP crystal of one conductivity type by atomic layer epitaxy,
The semiconductor device manufacturing method includes a step of effectively forming an InP Schottky junction by forming a metal electrode in contact with the GaAs epitaxial atomic layer.

[Industrial Field of Application] The present invention relates to a method of manufacturing a semiconductor device, and particularly relates to a method of manufacturing a semiconductor device including an InP Schottky junction.

Optoelectronic integrated circuits (OEICs) are one of the optical communication technologies that have continued to make remarkable progress in recent years.

One feature of this is that it has a photoelectric conversion section and an amplification section within the chip. In particular, for 0EIC in the 1 μm band, InGaAs/InP or InGaAsP/
Generally, an InP heterojunction element is used as a light receiving section, and an rnP field effect transistor (InP FET) is used as an amplifying section.

Therefore, there is a need for a technique for integrating various semiconductor devices on an InP crystal substrate.

[Conventional technology]

Conventionally, in an rnPFET, a pn junction and a depletion layer have been formed by thermally diffusing acceptor impurities into InP, which has n-type conductivity.

However, in this method using impurity diffusion, about 60
Since a high-temperature process of 0'C is required, the InP crystal is easily damaged, and the diffusion depth is difficult to control. The manufacturing process was also complex and costly.

On the other hand, a Schottky junction is a method for easily forming a depletion layer, but it is currently difficult to realize an InP Schottky junction.

[Problems to be Solved by the Invention] The present invention provides a low-temperature method that forms an extremely thin GaAs epitaxial atomic layer on an InP crystal to realize a depletion layer junction that effectively functions as an InP Schottky junction. The purpose is to provide a process to improve device characteristics, and to simplify the manufacturing process and reduce costs.

[Means to solve the problem]

The above problem is to
After forming the aAs epitaxial atomic layer 3 by atomic layer epitaxy, by forming the metal electrode 4 in contact with the GaAs epitaxial atomic layer 3, it is possible to effectively
The problem is solved by a semiconductor device manufacturing method including a step of forming a P Schottky junction.

[Operation] In the present invention, atomic layer eviction technology is used as a method for effectively forming an InP Schottky junction.

That is, a GaAs layer of one conductivity type is grown on a -conductivity type rnP crystal by several atomic layers to several tens of atomic layers.

FIG. 1 schematically represents a GaAs atomic layer on an InP crystal grown by atomic layer epitaxy.
A Ga layer and an As layer are sequentially grown one layer at a time on the InP crystal. Further, a metal electrode is attached thereon to form a GaAs Schottky junction. In GaAs.

For example, technology for making good Schottky junctions with metals such as AI has already been established.

By the way, if the GaAs layer is formed as thin as several tens of holes, a depletion layer will be formed within the InP crystal.

This means that an InP Schottky junction has been effectively formed, and it has been experimentally shown that it has the function of a Schottky junction.

〔Example] Two embodiments of the present invention will be described below.

FIGS. 2(a) to 2(d) are cross-sectional views for explaining the manufacturing process of a Schottky junction diode to which the method of the present invention is applied as an example. n-1nP in buffer layer.

3 is a GaAs epitaxial atomic layer, 4 is a metal electrode (AI electrode), and 5 is a substrate side electrode.

This will be explained below with reference to FIGS. 2(a) to 2(d).

Figure 2 (a) Sn-doped (100) n''-1n with reference thickness of 350 μm
On the P substrate (n −2X 10 “cm−’) l,
Sn-doped n 4nP with a thickness of 2 m (n = 2
A buffer layer 2 having a thickness of 1016 cm-'' is epitaxially grown by metal organic chemical vapor deposition (MOCVD).

Refer to FIG. 2(b) Using trimethyl gallium as a Ga source and arsine as an As source, a Sn-doped GaAs layer (n=2x1
0 cm-') is grown to 5 atomic layers by atomic layer epitaxy. 1 atomic layer refers to a pair of layers of Ga and As, and the thickness of 5 atomic layers is 14 layers.

Refer to FIG. 2(C), on the GaAs epitaxial atomic layer 3, an AI electrode 4 is formed by vapor depositing AI to a thickness of 1000 nm.

Referring to FIG. 2(d), Au and Sn are deposited on the n''-InP substrate 1 side to form an alloy to form a substrate side electrode 5 having a thickness of 3000 mm.

The AI electrode 4 forms a Schottky electrode, and the substrate side electrode 5
forms an ohmic electrode.

In the Schottky junction diode manufactured in this manner, the thickness of the interposed GaAs epitaxial atomic layer 3 is extremely small, and the spread of the depletion layer is accurately determined only by the carrier concentration of InP and the voltage applied from the outside. This was confirmed because the 1/C2-V plot obtained from the CV measurement was a straight line.

Further, the value of the ideality factor n determined from the forward current-voltage characteristic Ir = Aexp (qVy /nkT) became approximately 1.

From these facts, the depletion layer spreads within InP,
It can be considered that an almost perfect InP Schottky junction is effectively formed.

FIG. 3 shows an energy band diagram of this Schottky junction diode. A depletion layer is formed within the TnP crystal of the buffer layer 2, effectively forming an InP Schottky junction. Energy gap E9 between InP and GaAs
are respectively 1.35 eV at room temperature.

It is 1.42eV.

The dark current in the reverse direction was also significantly reduced compared to the conventional p-n junction case. This is because the growth temperature of the GaAs epitaxial atomic layer 3 is 450.degree. C., so that thermal damage, which has conventionally been a problem due to thermal diffusion, is almost eliminated.

G that effectively forms a good InP Schottky junction
The thickness of the aAs epitaxial atomic layer 3 is three or more atomic layers, and the upper limit is about 40 layers.

Note that in this example, n-type GaA is deposited on n-type InP crystal.
Although the s-epitaxial atomic layer is formed, a p-type GaAs epitaxial atomic layer may be formed on a p-type InP crystal.

Of course, the two or more methods described above can be applied to the formation of the gate portion of the rnPFET.

〔Effect of the invention〕

As explained above, according to the present invention, it is possible to effectively form an InP Schottky junction, which has been difficult to form conventionally.

The present invention can realize an InP Schottky junction without requiring a high-temperature process, so it is highly effective when applied to optoelectronic integrated circuits using InP as a substrate.

[Brief explanation of drawings]

FIG. 1 is a diagram schematically showing a GaAs atomic layer on an InP crystal. FIGS. 2(a) to 2(d) are cross-sectional views for explaining the manufacturing process of a horizontal-nodky junction diode according to an embodiment. FIG. 3 is an energy band diagram. In fig. 1 is an InP substrate and is an n''-InP substrate. 2 is a buffer layer and is an n4nP crystal. 3 is a GaAs epitaxial atomic layer. 4 is a metal electrode, and the old electrode 5 is a substrate side electrode and a P crystal. Hi's GαAS Omiko, q.

Claims (1)

[Claims] After forming a GaAs epitaxial atomic layer (3) of one conductivity type on an InP crystal (2) of one conductivity type by atomic layer epitaxy, a metal electrode (4) is formed in contact with the GaAs epitaxial atomic layer (3). A method for manufacturing a semiconductor device, comprising the step of effectively forming an InP Schottky junction.