JPS6226812A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To expand the adhesion area of a semiconductor substrate and to increase its adhesive power by a method wherein, after a metal thin film is formed into a desired shape by performing etching, a thick metal film is formed on the thin metal film, and the width of the thin metal film is made larger than the width of the thick metal film. CONSTITUTION:A barrier metal thin film 6a is formed on all over one main surface of a semiconductor substrate 1 in such a manner that emitter contacts 4 and the base contacts 5 are buried. After a negative resist film 12 is obtained, a thin metal film 11a is obtained by etching using said film 12 as a mask. Subsequently, the negative resist film 12 is removed, a positive type resist film is coated all over one main surface of the semiconductor substrate 1, a mask matching is performed and a developing process is conducted. A resist film 13 is formed on one main surface of the semiconductor substrate 1, gold is plated on the thin metal film 11, and a thick metal film 8 is formed.

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 manufacturing a semiconductor device that can simplify and improve the electrode structure of, for example, a high-frequency, high-output transistor.

[Conventional technology]

FIG. 7 is a cross-sectional view of a high-frequency, high-output transistor showing a conventional semiconductor device of this type.
(3) is a silicon oxide film formed on the main surface of this semiconductor substrate (1), and (4) and (5) are the emitter contact and base formed by etching this silicon oxide film (31). Contacts, (6I are the barrier metal thin films made of titanium tungsten formed on the main surface of the semiconductor substrate (11-2) in contact with the epitaxial layer (2) at the emitter contacts (41 and base contacts 151); 7) is this barrier metal thin film (
6) Electrode thin film made of sputtered gold formed on (8
) is formed on this electrode thin film (7) to form an electrode thin film (7).
Width 1.250 made of plated gold that also constitutes the electrode.
(9) is a glass coat formed on the entire principal surface of the semiconductor substrate (11-) on this thick metal film (8) and silicon oxide film (3).

A method of manufacturing a semiconductor device configured as described above is shown in FIG.
at 7;C\J2Fig. and a base contact (forming 51,
Next, a barrier metal thin film (6a) is formed on the entire main surface of the semiconductor substrate (11-) to fill these emitter contacts (4) and base contacts I5), and then an electrode thin film (7a) is formed in the spatter deposition device C. Figure 2 (a
). After that, the electrode thin film (7a
), apply a resist (10a) to the entire surface, align the masks, and develop the resist (II) formed between the emitter contact (4) and base contact (5) as shown in Figure 2 (bl). Furthermore, using this resist depression, plating gold is grown between the resist (101) and then the resist (IC1 is removed, as shown in FIG. 2).
A thick metal film +81 as shown in C) is formed. Next, using this thick metal film (8) as a mask, the electrode thin film (7) is etched [FIG. 2 (dl)], and the barrier metal (6) is further etched [FIG. 2 (e)], and finally; A glass coat 9) is formed over the entire semiconductor main surface on the thick metal film (8) and the oxide film (3) to obtain a semiconductor device as shown in FIG. 2(f).

[Problem that the invention seeks to solve]

The conventional manufacturing method for semiconductor devices is as described above. After forming the metal thick film (8), the electrode thin film (8) is formed using this as a mask.
7) and the barrier metal thin film (6), the width of each film is determined by the width of the thick metal film (8); Barrier metal film (approximately 0, 25 x in the order of 61
2 (/'), so the electrode thin film (
If the width of 7) is small (2 is the above barrier metal thin film (6)
), the semiconductor substrate (1), and the electrode thin film (7) become smaller, resulting in weaker adhesion, which causes the phenomenon of floating of the electrode thin film (7), resulting in a problem of lack of reliability.

The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a method for manufacturing a semiconductor device that can produce a semiconductor device without problems in terms of reliability.

[Means for solving problems]

The method for manufacturing a semiconductor device according to the present invention includes forming a metal thin film on a semiconductor substrate, selectively forming a resist film on the metal thin film, etching the metal thin film using the resist film as a mask, and then etching the metal thin film. , Portion C where this metal thin film is etched; This is a method in which a resist film is formed and a thick metal film is formed in the area excluding the resist film formation area.

[Effect]

In the method of manufacturing a semiconductor device according to the present invention, after etching a metal thin film to obtain a desired shape, a thick film of two metals is formed on the thin metal film. The width of the metal thin film can be made larger, the area of adhesion to the semiconductor substrate becomes larger, and the adhesion force can be increased.

〔Example〕

The following (= case where the embodiment of this invention is applied to a high frequency high output transistor)
f) Explain according to C. First, a semiconductor substrate (1) - the entire main surface (a dioxide film (31) is formed, and then this oxide film (31) is formed.
) to form an emitter contact (4) and a base contact (5), and then (- to bury these emitter contacts (4) and base contacts (5), a barrier is etched over the entire main surface of the semiconductor substrate (11-). Metal thin film (
5a) was formed, and further an electrode thin film (7a) was formed using sputter deposition apparatus C2 to form a metal thin film (lla) consisting of a barrier metal thin film (6a) and an electrode thin film (7a), as shown in FIG. 1(al). After that, the entire surface of the metal thin film (lla) is coated with Yunega's resist film,
The masks are aligned and developed to obtain a negative resist film selectively formed on the emitter contact (4) and base contact 15 as shown in FIG. 1 (blc). Furthermore, using this resist film (1) as a mask, the metal thin film (l
A thin metal film αυ having a shape as shown in FIG. 1(C) is obtained by etching the thin metal film αυ as shown in FIG.
) to form an electrode thin film (C1) as shown in Figure 1 (C1).
7) is obtained, and then the resist film 1 is made to sag by post-baking to cover the cross section of the electrode thin film (7),
The barrier metal thin film (6a) is etched as shown in Figure 1 (C).
) +: A barrier metal thin film (6) as shown is obtained. Thereafter, the negative resist film @ is removed, and a positive resist film is coated on the entire main surface of the semiconductor substrate (1), and developed without mask alignment.
The above semiconductor substrate (1) in the part where a) is etched
On the main surface (= resist film 3 is formed and this resist film C1
A thick metal film (
8). Finally, the zeta resist film (tS is removed [%1 Figure (e)]) the semiconductor substrate (11-the entire surface on the main surface 1
: Glass Co.) +91 is formed to obtain a semiconductor device as shown in FIG. 1(f).

In the semiconductor device formed by the above manufacturing method, after the metal thin film (lla) is etched to obtain the metal thin film layer υ of the desired shape, a metal thick film (8) is formed on the metal thin film aυ. Since the above-mentioned thick metal film (8
) The width of the thick metal film (8) can be made larger than the width of the metal thick film (8), and the adhesive area with the semiconductor substrate (1) can be increased to increase the adhesion force. If there is enough leeway within the range that does not cause lift in the wearing force,
Characteristics of High Frequency Highly Integrated Transistor For the same reason as above, the width of the metal thin film (Ll) can be made narrower than the width of the above embodiment in order to narrow the distance between contact holes. In addition, in the step of etching the metal thin film (lla), after etching the electrode thin film (7a), the resist film α is drooped to cover the cross section of the electrode thin film (7), and the barrier metal thin film (13a) is etched. It seems that the barrier metal thin film (&L
), the etching width is reduced by the amount covered, so a thin barrier metal film can be formed.

In the above embodiment, the semiconductor substrate [11] is formed with a silicon epitaxial layer (2), but it may be made of a material such as a compound conductor substrate.

In addition, the above embodiment (in the second case, barrier metal thin film (6)
Although it is made of titanium tungsten, it may be made of other metals such as platinum.

Further, in the above embodiments, a negative resist film is used as the resist film, but a positive resist film may be used.

〔Effect of the invention〕

As described above, C: According to the present invention, after etching a metal thin film to obtain a desired shape (2) on this metal thin film (
Since a two-metal thick film is formed, the width of the metal thin film can be made larger than the width of the metal thick film,
Since the bonding area with the semiconductor substrate becomes larger and the adhesion force can be increased, a highly reliable semiconductor device can be obtained.

[Brief explanation of drawings]

Fig. 1 is a cross-sectional view of a semiconductor device showing a case in which an embodiment of the present invention is applied to a high-frequency, high-output transistor C: manufacturing process sequence; Fig. 2 is a sectional view of a conventional method for manufacturing a high-frequency, high-output transistor; (; is a cross-sectional view of a semiconductor device shown. In the figure, (11 is a semiconductor substrate, (8) is a metal thick film,
υ is a metal thin film, α3 (13 is a resist film). Note that the same reference numerals in each figure indicate the same or equivalent parts.

Claims (3)

[Claims] (1) A step of forming a metal thin film on the entire surface of one main surface of a semiconductor substrate, a step of selectively forming a resist film on this metal thin film, a step of etching the metal thin film using this resist film as a mask, and a step of etching the above-mentioned resist film. a step of removing the film, a step of forming a resist film on one main surface of the semiconductor substrate in the portion where the metal thin film has been etched, and a step of forming a thick metal film on the metal thin film in the portion excluding the resist film forming portion. A method for manufacturing a semiconductor device having a process. (2) The metal thin film consists of a barrier metal thin film and an electrode thin film formed on the barrier metal thin film, and the step of etching the metal thin film using a resist film as a mask includes:
a step of etching the electrode thin film using the resist film as a mask; a step of dissolving the resist film to cover the cross section of the etched electrode thin film; and a step of etching the electrode thin film using the resist film after covering the cross section of the electrode thin film as a mask. 2. The method of manufacturing a semiconductor device according to claim 1, further comprising the step of etching a barrier metal thin film. (3) The method for manufacturing a semiconductor device according to claim 2, wherein the thick metal film and the thin electrode film are made of gold, and the thick metal film is formed by a plating method.