JPH04127423A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To obtain a method of forming a source-drain electrode whose electromigration-resistant property is excellent by a. method wherein, after a high-melting-point metal has been deposited on the whole surface, it is etched anisotropically and the sidewall of the high-melting-point metal is formed only on the side face of a pad. CONSTITUTION:At this manufacturing method of a semiconductor device, an insulating film 2 is deposited on a GaAs substrate 1 having an n-type layer, and a resist 3 in which a source-drain region has been opened is formed on the insulating film 2. Then, the resist 3 and the insulating film 2 are etched anisotropically; a metal 4 used to form a source-drain electrode is vapor- deposited. Then, the resist 3 is wet-etched and removed; a heat treatment is executed to form a source-drain electrode 4. Then, a pad 5 composed of a low-resistance metal is formed. Then, a high-melting-point metal Mo 6 is applied to the whole surface; the whole surface is etched; the sidewall of the Mo 6 is formed on the side face of the pad 5. Then, an insulating film 7 is deposited; a contact hole is formed; after that, an interconnection 9 is formed. As a result, it is possible to restrain the defect of a source-drain metal by an electromigration.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method of manufacturing a semiconductor device, and more particularly to a method of forming a 1-drain electrode in which electromigration is suppressed.

[Conventional technology]

FIG. 2 shows the main manufacturing process of a conventional sheath/drain electrode, and the conventional method will be explained below using this diagram.

First, as shown in Fig. 2 (8), a G
a Plasma CVD insulating film (2) on As substrate (1)
A resist (3) having an open sheath/drain region is formed on the insulating film (2) by a transfer technique.

Next, as shown in Figure 2 (6), using the resist (3) as a mask, the insulating film (2) is anisotropically etched by RIE or the like, and the metal (4) for forming the source/drain electrodes is etched. Deposit.

Next, as shown in FIG. 2(C), the resist (3) is removed by wet etching and heat treatment is performed at 400° C. for several minutes to form a sheath/drain electrode (4).

Next, as shown in FIG. 2(d), an insulating film (7) is deposited by a plasma CVD method or the like, and a contact hole (8) is formed by a transfer technique, an RIE method, or the like.

Next, as shown in FIG. 2(e), wiring (9) is formed by a vapor deposition/lift-off method or a seven-butter ion milling method.

[Problem to be solved by the invention] Conventional semiconductor device IJ! In the 1 manufacturing method, as shown in FIG. 2 (el), due to the alignment accuracy of the transfer technology, there are parts of nometrain metal that are more than 1 μm thick.

The sheath/drain electrode can usually obtain ohmic characteristics by heat-treating Ni and AuGa eutectic at about 400° C. to form an alloy, but this heat treatment increases the resistance of the sheath/drain metal itself by about five times.

Therefore, when the electric density becomes large, there is a problem in that electro-coil rations cause defects in only the sheath/drain metal parts.

This invention was made to solve the above-mentioned problems, and aims to form a sheath/drain electrode with excellent resistance to electrocoil ration. A method of manufacturing a semiconductor device according to the invention includes forming a pad made of a low resistance metal on a sheath/drain electrode, and forming a sidewall made of a high melting point metal on the side surface of the pad.

In this invention, since the portion of only the drain metal is reduced, defects in the sheath/drain metal due to electromigration are considerably suppressed, and highly reliable source/drain electrodes can be easily formed. I can do it.

[Example J An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows a method for manufacturing a semiconductor device according to an embodiment of the present invention in the order of steps.

As shown in FIG. 1 (8), an insulating film (2) is deposited on a G3As substrate (1) having an n-type layer by a plasma CVD method, and a sheath/drain region is deposited on the insulating film (2) by a transfer technique. A resist (3) with openings is formed.

Next, as shown in FIG. 1(b), using the resist (3) as a mask, the insulating film (3) is anisotropically etched by RIE method or the like, and the metal (4) for forming source/drain electrodes is etched. ) is vapor deposited. Next, as shown in FIG. 1(c), the resist (3) is removed by wet etching, and heat treatment is performed at 400 DEG C. for several minutes to form a sheath/drain electrode FM (41t-).

Next, as shown in Figure 1(d), a low-resistance metal is produced using the vapor deposition/lift-off method or the Nubatsuta ion milling method.
For example, a pad (5) made of Au/T1 is formed.

Next, as shown in FIG. 1(e), a high melting point metal such as Mo(6) is deposited on the entire surface by sputtering or vapor deposition, and as shown in FIG. 1(f), CF4+02 or 5F1
The entire surface is etched by reactive ion etching using a silicone material, and Mo (6) is etched only on the side of the pad (5).
) form the side walls of the

Next, as shown in the first oral history, an insulating film (7) is deposited by plasma CVD method, etc., and contact holes are formed by transfer technique, RIE method, etc., and then wiring ( 9).

In the above embodiment, the pad (5) is A u / T i
However, high melting point metal such as MOLW, A1.
Other multilayered metal films mainly made of low-resistance metals such as Au may also be used.

Further, although the side walls of U◯ are formed on the side surfaces of the pads, other high melting point metals such as W and Ti, or A1 may be used, and Au can also be used if a milling method is used for etching the entire surface.

[Effects of the Invention J As described above, according to the present invention, a pad made of a low resistance metal is formed on the sheath/drain region, and a side wall made of a high melting point metal is formed on the side surface of the pad, so that the sheath/drain region is
The portion containing only the drain metal is reduced, and loss of the sheath/drain metal due to electromigration can be suppressed, making it possible to obtain a highly reliable sheath/drain electrode.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing a method of manufacturing a semiconductor device according to an embodiment of the present invention, and FIG. 2 is a sectional view showing a conventional manufacturing process of a semiconductor device. (1) is a GaAs substrate with an n-type layer, (2), (7)
is an insulating film, (3) is a resist, (4) is a sheath/drain electrode, (5) is a pad, (6) is an 1ilo layer, (8)
(9) is a contact hole, and (9) is a wiring metal. Note that the same reference numerals in the figures indicate the same or equivalent parts. Agent Masuo Oiwa Figure 1 (Zeno1) Figure 1 (Zotn2) April 23, 1991

Claims (1)

[Claims] Forming an insulating film on a GaAs substrate having an n-type layer, opening source/drain regions, forming source/drain electrodes in the openings, and forming pads made of low resistance metal on the source/drain electrodes. A method for manufacturing a semiconductor device, comprising: depositing a high melting point metal on the entire surface and then anisotropically etching the entire surface to form a sidewall of the high melting point metal only on the side surface of the pad.