JPS6343317A - Selective metal deposition method - Google Patents

Abstract

PURPOSE:To deposite a metal with a simple construction and good selectivity by depositing a metal after depositing a doped semiconductor or a metallic film in the connection hole of an insulating material of a semiconductor substrate. CONSTITUTION:An N<+> layer 3 is provided in a Si substrate 1, an SiO2 film 2 is provided with an opening 4, which is coated with a doped polysilicon 5 and further with a photoresist 6, which is etched with a O2 plasma, left in the hole 4, and depressed from the SiO2 surface. The polysilicon 5 is etched away, and a W-film 7 is deposited. Since the edge of the Si 5 was previously depressed from the SiO2 film 2, the W does not swell above the SiO2 film. Since the side and the bottom of the connection hole are coated with the polysilicon according to this construction, the W grows from both the side and the bottom, and filling is completed with a film thickness about half that for the growth only from the bottom. In addition, since the bottom is coated with the polysilicon, no connection leakage occurs due to the penetration of the W.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a method for selectively depositing metals onto semiconductor substrates.

BACKGROUND OF THE INVENTION FIG. 3 shows an example of a conventional method for selectively depositing metal on a semiconductor substrate. In the figure, 8 is a Si substrate, 9 is a thermal oxide film with a thickness of about 1 μm, 10 is an n+ diffusion layer, 11 is a contact hole, 12 is a W film with a thickness of about 500 OA, and 13 is W grown on the thermal oxide film 9. 14 is the encroachment of W on the interface between the Si substrate 8 and the thermal oxide film 9, and 15 is the intrusion of W into the diffusion layer 10.

A reaction between WF6 gas and H2 gas was performed using a low pressure CVD method on a sample as shown in FIG. The W film 12 can be selectively deposited inside the contact hole 11 using the method. [For example, T, Morfya etal, IEE, IEDM (IEEE, IEDM) 83 P2
S5) Problems to be Solved by the Invention However, in such conventional W selective deposition methods, selectivity may deteriorate due to differences in conditions such as surface treatment of the substrate before deposition, deposition temperature, gas flow rate, etc.

The state of the interface with the Si substrate 8 may deteriorate, and as shown in FIG. W on the interface with
Encroachment 14 of W occurs, W enters the diffusion layer 15, and this causes various problems such as short-circuiting of the junction.

The present invention has been made in view of this point, and an object of the present invention is to provide a method for selectively depositing and removing metals with a simple structure and good selectivity.

Means for Solving the Problems In order to solve the above problems, the present invention forms a contact hole in an insulating film deposited on the surface of a semiconductor substrate, and forms a semiconductor or metal film doped with impurities in the contact hole, such as a doped polysilicon film. By selectively depositing a metal, such as W, after depositing the metal, it is possible to provide a method for selectively depositing a metal, which has good selectivity and does not penetrate into the encroachment diffusion layer.

Effects According to the present invention, with the above-described structure, the side surfaces and bottom surface of the inside of the contact hole are covered with doped polysilicon, so that W grows from both the side surface and the bottom surface of the contact hole, so that the amount of film is about half that of filling only from the bottom surface. The contact hole can be filled thickly, which is advantageous in terms of selectivity, and the bottom surface of the contact hole is doped with pol.
Since it is covered with ysi, there is no need to worry about junction leakage or encroachment due to the intrusion of W.

Embodiment FIG. 1 shows a first embodiment of the selective metal deposition method of the present invention.

In the figure, 1 is a semiconductor Si substrate, 2 is an oxide film with a thickness of about 1 μm,
3 is an n+ diffusion layer, 4 is a contact hole, and 6 is a thickness of about 1
6 is a photoresist, and 7 is a W film.

As shown in FIG. 1A, an n+ diffusion layer 3 is formed on a St 2 substrate 1, an oxide film 2 is deposited, and a contact hole 4 is opened, after which doped poLysi 5 is deposited over the entire surface as shown in FIG. A shift resist was applied to the sample prepared in this manner by the usual sulpine coating method, and the photoresist was etched using 02 plasma so that the photoresist remained only in the contact holes, as shown in FIG. 1C. At this time, the photoresist 6 is recessed from the surface of the oxide film 2 by the thickness of the W film to be deposited. The doped po 1 yS i 5 is etched using the photoresist 6 as a mask, as shown in FIG. 1d. Furthermore, photoresist 6
The etched version is shown in Figure 1e. This figure 1 e
Figure 1f shows a sample prepared in the manner described above with a W film of approximately 600° thick deposited thereon. pre-doped p
Since the edge of the olysi 6 is formed to be recessed than the oxide film 2, the W film 7 does not rise above the oxide film 2.

If the method of the present invention is used, W
Since the film can be buried, the contact hole can be filled with a film thickness that is approximately half that of filling from the bottom of the contact hole, which shortens process time and improves varnish loops, as well as improving selectivity. It is also advantageous in terms of Also, the bottom of the contact is doped poly
Since it is covered with i, there is no concern that problems such as encroachment or short circuits due to penetration of W into the n+ diffusion layer will occur. Furthermore, doped polyS i
Since the contact resistance is used, there is no concern that the contact resistance will deteriorate and stable contact characteristics can be obtained.

Note that in this example, a Si substrate is used as the substrate,
Although W was selectively deposited directly onto the Si surface, similar effects can be obtained even on surfaces other than the Si surface, for example, surfaces where metals such as M, Ti, or W are exposed. Also, an oxide film was used as the insulating film.

It goes without saying that an insulating film other than an oxide film such as a 313N4 film or a multilayer film thereof may be used. In addition, materials other than Si, such as G, can be used as the substrate material.
A similar effect can be obtained by using aAg or the like. It goes without saying that an nfc/p+ diffusion layer for n+ diffusion N k may be used as the diffusion layer.

FIG. 2 shows a second embodiment of the selective metal deposition method of the present invention. In the figure, 16 is an 81 board, 17 is a thickness of about 1
μm oxide film, 18 is doped polysi, 19 is a contact hole, 20 is a contact diffusion layer, 21 is W
It is a membrane.

In the same manner as in FIG. 1 of the first embodiment, doped poly is added into the contact pole as shown in FIG. 3a.
After forming si 18, the third
A contact diffusion layer 20 is formed as shown in the figure, and W is selectively deposited as shown in FIG. 3C. If this method is used, there is no need to perform contact diffusion before depositing W.

The process can be greatly simplified.

Effects of the Invention As described above, according to the present invention, very good selective deposition of metal can be performed with an extremely simple configuration.
It is extremely useful in practice.

[Brief explanation of the drawing]

1 and 2 are process cross-sectional views showing a selective deposition method of W in an embodiment of the present invention, and FIG. 3 is a process cross-sectional view showing a conventional selective deposition of W. 1...St substrate, 2... Oxide film, 3
......n diffusion layer, 4...contact hole, 6...doped polysi, 6.
...Photoresist, 7...W film. Name of agent: Patent attorney Toshio Nakao and one other person

Claims (5)

[Claims] (1) When selectively depositing metal on the surface of a semiconductor substrate, a step of depositing an insulating film on the surface of the semiconductor substrate and forming a contact hole, and depositing a semiconductor or metal film doped with impurities on the side and bottom surfaces of the contact hole. A method for selectively depositing a metal, comprising the steps of: forming a contact hole; and selectively depositing the metal in the contact hole. (2) The selective metal deposition method according to claim 1, wherein contact diffusion is performed on the surface of the semiconductor substrate within the contact hole from a semiconductor or metal film doped with impurities within the contact hole. (3) The selective metal deposition method according to claim 1, in which doped polysilicon is used as the semiconductor. (4) In the step of forming a semiconductor or metal film on the side and bottom surfaces of the contact hole, the step of depositing the semiconductor or metal film on the entire surface of the semiconductor substrate in which the contact hole is formed, and the step of depositing the semiconductor or metal film on the entire surface of the semiconductor substrate in which the contact hole is formed; or a step of forming a coating film having etching characteristics different from those of the metal film and the insulating film so that the surface thereof is flattened, and a step of etching the coating film to leave the coating film only in the contact hole. , a step of removing the semiconductor or metal film using the unused film as a mask, and forming the semiconductor or metal film only on the side and bottom surfaces of the contact hole; and a step of removing the coated film. A method for selectively depositing the metal according to scope 1. (5) In the step of leaving the coating film only in the contact hole, the coating film is left in such a manner that the surface of the coating film is recessed from the surface of the insulating film. Selective deposition of metals.