JPS62199035A - Selective depositing method for metal - Google Patents

Abstract

PURPOSE:To select and deposit metal very excellently, by overlapping an insulating film having excellent adhesion on the surface of a semiconductor substrate, and covering a part other than a connecting window part with an insulating film, on which metal is hard to be deposited. CONSTITUTION:A thermal oxide film 2 is formed on an Si substrate 1. A PSG film 3 is overlapped by a CVD method and a window is opened. When a W film 5 is deposited by a CVD method, it is hard to be deposited on the PSG but is selectively deposited on the Si substrate. In this method, the interface between the substrate 1 and the thermal oxide film has the excellent adhesion without the intrusion of the metal. A metal nucleus is not grown on a part other than the connecting window.

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. 2 shows an example of a conventional method for selectively depositing metal on a semiconductor substrate. In the figure, 6 is an St substrate, 7 is a thermal oxide film, 8 is a contact hole, 9 and 11 are W (tungsten) films deposited by low pressure CVD, 10 is a W nucleus grown on the thermal oxide film, and 12 is a W encroachment.

After forming a contact hole 8 with a diameter of about 2 μm in a thermal oxide film 7 with a thickness of about 1 μm formed on the St substrate 6, the contact hole is selectively formed using a reaction between WF6 gas and H2 gas by the low pressure CVD method. A W film 9 can be deposited within the 83 (T, Moriya a).
t.

al, IEEE, IEDM83) P2S
5).

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. In this case, a solid W nucleus 10 as shown in FIG. 2 is formed. It is difficult to remove this W nucleus 11, which poses a major problem in the process.

In addition, PSG film is known as a film in which this W nucleus 10 is difficult to grow (for example, Yasushi Oyama et al., Electrochemical Society Electronic Materials Committee, Semiconductor, Integrated Circuit Technology, 28th Symposium 60 Years Lecture Proceedings, P1o9), but P
In order to obtain the SG film, a deposition method such as the CVD method must be used, and the adhesion of the interface between the insulating film obtained by the deposition method and the 81 substrate is inferior to that of a thermal oxide film. There was a problem in that W encroachment 12 as shown in Figure (q) occurred.

The present invention has been made in view of these points, and an object of the present invention is to provide a selective metal deposition method with a simple configuration and good selectivity.

Means for Solving the Problems In order to solve the above problems, the present invention forms a first insulating film having good adhesion to the surface of the semiconductor substrate on the surface of the semiconductor substrate,
Furthermore, after depositing a second insulating film in which metal deposition is less likely to occur on the first insulating film, the first and second insulating films are patterned to form a contact hole reaching the semiconductor substrate. The present invention provides a method for selectively depositing metal with good selectivity and without encroachment of W by selectively depositing metal.

Effect: With the above-described configuration, the present invention forms an insulating film with good adhesion on the surface of the semiconductor substrate in the contact hole portion, and the sample surface other than the contact hole portion is covered with an insulating film that is unlikely to cause metal deposition. Therefore, metal encroachment is less likely to occur in the contact hole portion, and there is no worry that metal nuclei will grow in areas other than the contact hole.

Embodiment FIG. 1 is a diagram showing an embodiment of the selective metal deposition method of the present invention. In the figure, 1 is a semiconductor Si substrate, 2 is about 1 μm thick
3 is a thermal oxidation film of approximately 1000 nm thick using the atmospheric pressure CVD method.
4 is a contact hole, and 5 is a W (tungsten) film.

The sample prepared as shown in Figure 1(a) was subjected to normal reduced pressure CV.
D (Chemical Vapor Deposit
Figure 1 shows a gold JIIEW film selectively deposited in about 8,000 contact holes 4 by the reduction action of WF6 gas and H2 gas using the ion (vapor phase growth) method.
Shown in b).

It is known that W is difficult to deposit on the PSG film 3 (for example, Yasushi Oyama et al., Electrochemical Society Electronic Materials Committee, Semiconductor, Integrated Circuit Technology, Proceedings of the 28th Symposium 60 Years, P2O3 ), it is possible to selectively deposit a thick XAW film, and since the interface between the Si substrate 1 and the thermal oxide film 2 has good adhesion, there is no fear of W encroachment. In this way, W can be selectively deposited with good selectivity and without encroachment.

Note that in this example, a Si substrate is used as the substrate,
Although W was selectively deposited directly on the Si surface, similar effects can be obtained on surfaces other than the Si surface, for example, on surfaces where metals such as TL, Al, or W are exposed. In addition, although a PSG film on a thermal oxide film was used as the insulating film, the lower insulating film may be any film that has good adhesion to the SL substrate, such as the St○2 film made by CVD method, and the upper insulating film is B
Any film, such as a PSG film, that does not easily cause W deposition may be used. It goes without saying that a structure having three or more layers may also be used. In addition, as a substrate material, for example, GaAs etc., S
Of course, materials other than t may be used.

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

[Brief explanation of drawings]

FIG. 1 is a process cross-sectional view showing a W selective deposition method according to an embodiment of the present invention, and FIG. 2 is a process cross-sectional view showing a conventional W selective deposition method. 1... Si substrate, 2... Thermal oxide film, 3
... psGwA by normal pressure CVD method, 4...
...Contact hole, S...W film, 6...
...Si substrate. Name of agent: Patent attorney Toshio Nakao and 1 other person3-
P, 3(:, pus 4 doo ---]] Nda 7LT, -
Le 5 s-w compliance Figure 2

Claims (2)

[Claims] (1) When selectively depositing metal on the surface of a semiconductor substrate by the CVD method, a step of forming a first insulating film having good adhesion to the surface of the semiconductor substrate on the surface of the semiconductor substrate; a step of depositing a second insulating film in which metal deposition is less likely to occur, and patterning the first and second insulating films to form a contact hole reaching the semiconductor substrate to selectively deposit metal. A selective metal deposition method comprising the steps of: (2) The selective metal deposition method according to claim 1, in which a PSG film is used as the second insulating film.