JPH02256231A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To deposit numerous kinds of metal selectively without damage at low temperature by a method wherein deposition is performed by using electrochemical reaction while a semiconductor substrate part with metallic films being deposited is maintained at negative potential. CONSTITUTION:A semiconductor substrate 1 held on a cathode 3 kept at negative potential with respect to an anode 5 is made to be at negative potential with respect to the anode 5 by an electrical connected part 4 between the cathode and the semiconductor substrate. Thus metallic element or metallic complex gas 7 positively ionized among reaction gas is selectively deposited in a contact hole a having conductivity opened on a dielectric film 2 as a metallic film 8 by a method having the same principle as that of electroplating but is not deposited on a conductive film having no conductivity. Thus selective deposition only on a conductive part is possible so that plugging the contact hole part 9 can be simply realized without few limitation in materials while use of no pyrolytic reaction or radical reaction permits deposition at low temperature so that problems of damage to a semiconductor element can be avoided.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for manufacturing a semiconductor device, and in particular to a film formation technique that can selectively deposit a large number of metals on a semiconductor substrate in a metal vapor phase. be.

[Conventional technology]

FIG. 3 is a cross-sectional view of a semiconductor device showing a conventional method of selectively depositing a metal film on a semiconductor substrate.

In the figure, (1) is a semiconductor substrate, (2) is a dielectric film formed on the semiconductor substrate, (9) is a contact hole opened in a predetermined part of the dielectric film (2), and (A) is a semiconductor substrate. A susceptor that applies heat to the substrate (1), (4) a reactive gas,
(a) is a thermally decomposed reactive species or reactive radical, (
C) is the deposited metal film.

Next, the operation will be explained. The metal film (c) is formed by a thermal decomposition reaction of the reaction gas (e) by heat applied from the susceptor (a), so the metal film (c) is deposited on the entire surface of the semiconductor substrate (1). . Therefore, photo-etching is required in a subsequent process to fill the contact hole (9).

Further, the reaction may not be based on heat, but instead may use a radical reaction such as glow discharge, but in this case as well, the metal film is deposited over the entire surface of the semiconductor substrate (1).

As an exception, very specific materials such as tungsten are selectively deposited into the contact holes (9).

[Problem to be solved by the invention]

The conventional method of selectively depositing a metal film on a semiconductor substrate is carried out as described above, so the semiconductor substrate is electrically floating and the deposition reaction is a thermochemical reaction or a radical reaction, and the semiconductor substrate It was difficult to deposit selectively on the top.

Furthermore, materials that can be selectively grown are extremely limited, such as tungsten. Furthermore, during deposition, the semiconductor substrate is exposed to high temperatures or discharge, which causes problems such as damage to semiconductor elements and limitations on the applicable process.

The present invention has been made to solve the above-mentioned problems, and it is an object of the present invention to provide a method by which a large number of metals can be selectively deposited at low temperatures without damage.

[Means to solve the problem]

The method for depositing a metal film according to the present invention maintains the surface of a conductive portion of a semiconductor substrate to be deposited at a predetermined cathode potential, and causes an electrochemical reaction with a positively ionized reaction gas. It is.

[Effect]

The method of depositing a metal film in this invention deposits metal only on the conductive portion of the semiconductor substrate by causing an electrochemical reaction with a positively ionized reactive gas on the surface of the conductive portion of the semiconductor substrate. let

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings. 1st
The figure is a schematic cross-sectional view showing a method of selectively depositing a metal film on a semiconductor substrate.

In the figure, (1) is a semiconductor substrate, (2) is a dielectric film formed on the semiconductor substrate (1), and (9) is a dielectric film (2).
), (3) is the cathode that holds the semiconductor substrate (1), (4) is the electrical connection between the cathode (3) and the semiconductor substrate (1), (5) is the anode , (6
) is the reaction gas, (7) is the positively ionized metal element or metal complex gas in the reaction gas (6), and (8) is the positively ionized metal element or metal complex gas (7) in the reaction gas (6). This is a metal film deposited only on the contact hole (9) by a chemical reaction.

FIG. 2 is a cross-sectional side view showing the basic configuration of a reaction chamber for realizing the manufacturing method shown in FIG. 1.

In the figure, (1) to (5) are equivalent to those shown in FIG. αυ is the reaction chamber, (2) is the reaction gas inlet that leads the reaction gas (6) to the reaction chamber αυ, time is the exhaust port, and 0 is the shade! (3) is a power source that applies a negative potential to the anode (5).

Next, the operation will be explained.

The semiconductor substrate (1) held on the cathode (3) which is kept at a negative potential with respect to the anode (5) is connected to the anode (5) by the electrical connection part (4) between the cathode and the semiconductor substrate. ), the positively ionized metal element or metal complex gas (7) in the reaction gas (6) is transferred to a conductive contact hole opened on the dielectric film (2). (9) is selectively deposited as a metal film (3) using the same principle as electroplating, and is not deposited on a dielectric film that does not have conductivity.

〔Effect of the invention〕

As described above, according to the present invention, the part of the semiconductor substrate where the metal film is being deposited is kept at a negative potential, and the deposition is performed using an electrochemical reaction, so that the metal film can be selectively deposited only on the conductive part, like electrolytic plating. Because it can be performed, it is easy to fill contact holes with few material restrictions, and because it does not use conventional thermal decomposition reactions or radical reactions, it can be deposited at extremely low temperatures, and there is no problem of damage to semiconductor elements. There is an effect that can be avoided.

[Brief explanation of drawings]

FIG. 1 is a schematic cross-sectional view showing a method for selectively depositing a metal film on a semiconductor substrate according to an embodiment of the present invention, and FIG. 2 is a basic reaction chamber for realizing the manufacturing method shown in FIG. FIG. 3 is a cross-sectional side view without showing the structure, and is a cross-sectional view of a semiconductor device showing a conventional method of selectively depositing a metal film on a semiconductor substrate. In the figure, (1) is a semiconductor substrate, (February dielectric film,
(3) is the cathode, (4) is the electrical connection between the cathode and the semiconductor substrate, (5) is the anode, (reactant gas, and (7) is the positively ionized metal element or metal complex gas. , (8)
is a metal film, (9) is a contact hole, Oυ is a reaction chamber,
(6) is a reaction gas inlet, α4 is an exhaust port, and 0 is a power source. In addition, in the figures, the same reference numerals indicate the same or equivalent parts.

Claims (1)

[Claims] A step of introducing a semiconductor substrate formed by forming a dielectric film pattern on a conductive substrate into a reaction chamber and placing it on a cathode, a step of evacuating the reaction chamber, and a step of holding the semiconductor substrate at cathode potential. A step of introducing an ionized reaction gas into a reaction chamber, or a step of introducing a reaction gas into a reaction chamber and ionizing it by electric discharge, and a step of applying a positively ionized metal or its complex gas to a semiconductor substrate held at a cathode potential. A method for manufacturing a semiconductor device, which consists of a step of depositing metal only on conductive parts of the surface of a semiconductor substrate by a cathodic reaction.