JPH0319329A - Method of embedding metal - Google Patents

Abstract

PURPOSE:To enable a metal not polluted by an impurity to be embedded by a method wherein an organic film is patterned using a resist as a mask, a metal is filmed in vacuum and then the resist as well as the metal on the resist are removed. CONSTITUTION:A silicon substrate 11 is coated with polyimide 12 which is further coated with conventional positive resist 13. Later, photoresist is patterned and then a through hole 14 is formed in the polyimide film 12 using the photoresist as a mask. Next, a low melting point metal 15 such as In is evaporated on the whole surface of the substrate 11 using a vacuum evaporator. Besides, the evaporating metal is not necessarily limited to In but an alloy such as Au-Sn or Au-In may be applicable. Finally, an etchant capable of solving photoresist but incapable of solving the polyimide e.g. butyl acetate is used so as to selectively solve and remove the photoresist 13 simultaneously removing the In 15 on the photoresist.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method of embedding metal into an opening in an organic film on a semiconductor substrate.

(Prior Art) As a method of embedding metal into an organic film opening conventionally formed on a semiconductor substrate, a method using electrolytic plating is known (Shinichi Muramatsu, Japanese Patent Application Laid-open No. 197857/1983).
. FIG. 3 shows a cross-sectional view of a process for explaining a method of embedding metal into organic resist openings using electrolytic plating.

First, a cathode electrode material (32) for electrolytic plating is formed on a semiconductor substrate (31), and then a photoresist (33) is applied as an organic film (FIG. 3(a)). Thereafter, a through hole (34) is formed in the photoresist by a photolithography process (FIG. 3(b)).

After that, the entire semiconductor substrate (31) is covered with a plating solution (3).
6) by applying a negative potential to the cathode electrode (32) and applying a positive potential to the anode electrode (35) in the plating solution to deposit the metal (37) in the through hole portion (34). (Figure 3 (C)). Finally, the semiconductor substrate is washed with water and dried to obtain a structure in which the metal (37) is embedded in the resist opening (FIG. 3(d)).

(Problem to be Solved by the Invention) However, in the above-mentioned manufacturing method, it is necessary to immerse the entire substrate in the plating solution, and the cations such as alkali metals and anions such as chlorine ions contained in the plating solution are absorbed into the organic film. Enter the inside (here, the resist (33)). These impurity ions that have entered the resist cannot be removed even if the semiconductor substrate is washed with water.

An object of the present invention is to provide a method for embedding metal without contamination by impurities.

(Means for Solving the Problems) The present invention includes a step of forming an organic film on a semiconductor substrate, a step of applying a resist on the organic film, a step of patterning the resist, and a step of masking the resist. a step of patterning the organic film as a method; a step of forming a metal film in vacuum; and a step of patterning the resist and the metal on the resist using an enoting solution that does not dissolve the organic film but only dissolves the resist. This is a metal embedding method characterized by metal removal.

(Function) Since the method of the present invention uses a metal film in a vacuum (for example, vacuum evaporation, etc.) without using an electrolytic plating process, there is no concern that the organic film will be contaminated by impurities such as alkali metal ions. There isn't. Furthermore, since the metal is coated with a resist applied on the organic film, there is no step in which the coated metal directly contacts the organic film. Therefore, there is no fear that the metal to be embedded in the organic film will enter.

(Example) Hereinafter, an example of the present invention will be described based on the drawings. A case will be explained in detail by taking as an example a case where a polyimide having good heat resistance is used as an organic film and a low melting point metal such as In is embedded in an opening of the polyimide film coated on a silicon substrate which is a semiconductor substrate.

First, polyimide (12) is coated on a silicon substrate (11), and then a normal "bodi resist" (13) is coated (Fig. 1(a)).Then, the photoresist is patterned (the first Further, using the photoresist as a mask, a through hole (14) is formed in the polyimide film (12) (FIG. 1(C)). Then, using a vacuum evaporation device, In etc. low melting point metal (15
) is deposited on the entire surface of the silicon substrate (FIG. 1(d)). Note that the metal to be vapor-deposited is not limited to In, but also Au-
An alloy such as Sn or Au-In may also be deposited. Finally, using an etching solution that dissolves the photoresist but does not dissolve polyimide, such as butyl acetate, the photoresist (13) is selectively dissolved and removed, and at the same time, the In (15) on the photoresist is also removed. (Figure 1(e)). Through the series of steps described above, metal such as In is embedded in the polyimide film opening.

In addition, in the above-mentioned example, the case where polyimide was used as the first organic film on the semiconductor substrate was shown, but other organic films and materials containing Asahi materials such as silicon in organic polymers may also be used. It belongs to the category of organic film as used in the present invention.

Furthermore, as shown in FIG. 2, a through hole (14) is formed in the organic film (l2) using the resist (13) as a mask (FIG. 2(a)), and furthermore, a through hole (14) is formed in the organic film (l2) using the resist (13) as a mask. 11) is partially etched (Fig. 2(b)
)) Then, the metal film (15) is deposited (Fig. 2(C))
The resist (13) may also be selectively dissolved and removed. By doing so, it is possible to obtain a structure in which metal is embedded in the opening of the semiconductor substrate and a part of the semiconductor substrate below the opening (FIG. 2(d)).

(Effects of the Invention) As detailed above, according to the method of the present invention, there is no need to worry about impurities such as alkali ions entering the organic film into the organic film opening formed on the semiconductor substrate. Without any
It becomes possible to embed metal. Furthermore, if a heat-resistant organic material such as polyimide is used as the organic film and a low-melting point metal such as In or a low-melting point alloy such as Au-In is embedded in the opening of the heat-resistant organic film by the method according to the present invention, heat-resistant Another feature is that a low melting point metal (or alloy) pool can be formed within the plane of the organic film.

[Brief explanation of the drawing]

1 and 2 are manufacturing process cross-sectional views for explaining an embodiment of the present invention, and FIG. 3 is a cross-sectional process view for explaining a conventional example. 11... silicon substrate, 12. ...Polyimide, 13
...Bosi type resist, 14...Through hole, 15
...In, 31... semiconductor substrate, 32. ．．・Cathode electrode for electrolytic agate, 33...resist, 34...
Through hole, 35... Anode electrode for electrolytic agate, 36... Plating solution, 37... Electrolytic deposited metal

Claims (1)

[Claims] a step of forming an organic film on a semiconductor substrate; a step of applying a resist on the organic film; a step of patterning the resist; a step of patterning the organic film using the resist as a mask; and removing the resist and the metal on the resist using an etching solution that does not dissolve the organic film but only dissolves the resist.