JPS6410931B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of manufacturing a semiconductor device, and particularly to a method of manufacturing a semiconductor device including an ion implantation process.

Among semiconductor materials, in compound semiconductors such as GaAs, in the activation annealing temperature step after ion implantation, one of the semiconductor constituent elements often dissociates during heating and escapes from the semiconductor. In order to prevent this, a method has conventionally been adopted in which an insulating film such as SiO ₂ or Si ₃ N ₄ is applied as a cap material to the semiconductor surface to suppress the escape of semiconductor constituent elements during heating.

FIGS. 1a to 1f are diagrams for explaining a method of manufacturing a conventional GaAs shot barrier gate field effect transistor (hereinafter abbreviated as MESFET), and are cross-sectional views of the MESFET in main steps. In the same figure, a MESFET is mounted on a semi-insulating GaAs substrate 11.
Impurity ions for forming an active layer are selectively implanted to form an implanted region 21 (FIG. 1a).
CVD as a cap material on the surface of the GaAs substrate 11
After depositing a SiO ₂ film 31 by (Chemical Vapor Deposition) method (Fig. 1b), and activating impurities by annealing for 20 minutes in an H ₂ atmosphere at 800°C,
The SiO ₂ film 31 is removed (FIG. 1c). 22 is an activated implantation region. Next, an Al film 41 is deposited as a shot barrier gate electrode metal (FIG. 1d), and the gate electrode 411 is left by etching (FIG. 1e). Next, a multilayer metal film consisting of AuGe alloy and Ni was sequentially deposited and heated at 420°C.
By annealing in an H ₂ atmosphere, a source electrode 511 and a drain electrode 512 are formed (FIG. 1f), and a GaAs MESFET is manufactured.

However, in such conventional methods, the cap in the annealing process and the electrodes of the semiconductor device are formed using different materials, so a process of depositing and etching each material is required, which increases the manufacturing process. It has the disadvantage that it is complicated.

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for manufacturing a semiconductor device that eliminates the above-mentioned drawbacks and has a simple and short manufacturing process.

According to the present invention, the steps include a step of implanting ions into a compound semiconductor, a step of depositing a metal film on the surface of the compound semiconductor that does not cause a chemical reaction with the compound semiconductor at a temperature below an annealing temperature in a subsequent step, and The method includes a step of annealing the compound semiconductor using the film as a cap material to activate implanted ions, and a step of leaving at least a portion of the metal film as an electrode of a compound semiconductor device and removing the remaining metal film. A method for manufacturing a compound semiconductor device is obtained.

Next, embodiments of the present invention will be described using the drawings.

FIGS. 2a to 2d are drawings for explaining one embodiment of the present invention, and are cross-sectional views of the MESFET in the main manufacturing steps when the active layer of the GaAs MESFET is formed by ion implantation.

In the figure, 11 is a semi-insulating GaAs substrate, on which Si ions are accelerated at an accelerating voltage to form an active layer.
Selective implantation is performed under conditions of 70 KeV and a dose of 2.5×10 ¹² cm ⁻² to form an implanted region 21 (FIG. 1a).
As the shot barrier gate electrode metal, a TiW alloy that does not react with GaAs at the annealing temperature in the post-process is used.
Sputter deposited to a thickness of 5000 Å (Figure 2b),
The TiW alloy film 41 is used as a cap material and annealed in H ₂ at 800° C. for 20 minutes to activate the implanted impurities.
Next, a gate electrode 411 is left by a dry etching method using SF ₆ as an etching gas (FIG. 1c), and a laminated metal film in which AuGe alloy and Ni are sequentially laminated is selectively deposited by a normal lift-off method.
A source electrode 511 and a drain electrode 512 are formed by annealing in H ₂ at 420°C for 1 minute.
We completed a GaAs MESFET (Figure 1d).

In this manufacturing method, since the cap material in the annealing process and the MESFET gate electrode material are the same material, the cap material removal step and gate electrode material deposition step of the conventional method can be omitted, simplifying and shortening the process. has become possible, and the yield of MESFET has improved.

In this example, the cap material for the annealing process was
Although only the case where it is used as a gate electrode of MESFET has been described, it can also be used as other electrodes depending on the material. It goes without saying that the present invention is equally effective in the case of compound semiconductor devices other than MESFETs, or compound semiconductor devices using compound semiconductor materials other than GaAs.

[Brief explanation of the drawing]

Figures 1a to 1f are diagrams for explaining the conventional method of manufacturing a short barrier gate field effect transistor, including cross-sectional views of the MESFET in the main steps;
FIGS. 2a to 2d are diagrams for explaining an embodiment of the present invention, and are cross-sectional views of a MESFET in main steps. 11... Semi-insulating GaAs substrate, 21... Injection region,
22...Activated implantation region, 31...SiO ₂ film,
41... shot metal film, 411... gate electrode,
511... Source electrode, 52... Drain electrode.

Claims (1)

[Claims] 1. A process of ion implantation into a compound semiconductor,
A step of depositing a metal film on the surface of the compound semiconductor that does not cause a chemical reaction with the compound semiconductor at a temperature below the annealing temperature in a subsequent step, and annealing the compound semiconductor using the metal film as a cap material to activate the implanted ions. 1. A method for manufacturing a compound semiconductor device, comprising: a step of leaving at least a part of the metal film as an electrode of the compound semiconductor device, and removing the remaining metal film.