Method of forming interlayer film

Details Method of forming interlayer film Method of forming interlayer film

1999-03-04

2001-04-24

Nelms, David (Department: 2818)

Semiconductor device manufacturing: process

Coating with electrically or thermally conductive material

To form ohmic contact to semiconductive material

C438S624000

Reexamination Certificate

active

06221756

ABSTRACT:

BACKGROUND OF THE INVENTION
This invention relates to a method of forming an interlayer film, particularly to a method suited for forming an interlayer insulating film in manufacturing semiconductor devices.
In manufacturing semiconductor devices, a method is often adopted in which fluid source materials are used to form interlayer insulating films so as to fill up troughs on a substrate surface formed by wiring patterns thereon to assure a high smoothness of the substrate surface. When using the fluid source material for forming the interlayer insulating film, the fluid film, while it is being deposited, flows into the troughs between patterns from the top surfaces of the wiring patterns, resulting in filling the troughs.
When forming such an interlayer insulating film, a single step film deposition process is carried out in the related method to obtain the desired film thickness (for example, see M. Matsuura and M. Hirayama, 1995 Dry Process Symposium, pp. 261-268 (1995)).
Such a method of forming interlayer insulating films, however, causes an undesirable phenomenon that, when the troughs on the substrate surface are formed by a plurality of patterns of differing widths, the thickness of the film formed on each of those patterns varies with dependence on pattern widths (hereinafter, this phenomenon is referred to as poor global smoothness), resulting in differences in level. This is considered to be as follows. When the film is deposited, the fluid film swells on each pattern due to the surface tension. On a wide pattern, the film swells more despite the fluid film flowing into the trough between patterns from the edge of the pattern as the film becomes thicker, so that when the film deposition ends, the film is formed with a thickness as swelled and results in becoming thicker than on a narrower pattern.
If an interlayer insulating film has such poor global smoothness, there occurs problems such as the step coverage of the formed interlayer insulating film becoming poor and a wiring layer or the like becoming thin partially when formed on the interlayer insulating film.
In view of foregoing, it is an object of this invention to provide a method of forming an interlayer film, which can eliminate the above phenomenon that the film formed on each pattern becomes uneven in thickness due to differences in width of those patterns formed on the substrate.
SUMMARY OF THE INVENTION
Above object is achieved by a method of forming an interlayer film in which the interlayer film is formed by a process comprising a plurality of steps in each of which a portion of the film is deposited with the same source material under a condition of providing the portion of film with different fluidity.
In a method of forming an interlayer film according to the first aspect of the present invention, a portion of the interlayer film is at first deposited under a condition of providing the portion of film with relatively reduced fluidity, so that the film is deposited with an almost uniform thickness regardless of any pattern width on the substrate. After this, the rest portion of the film is deposited under a condition of providing the rest portion of the film with relatively increased fluidity so as to fill up the trough between the patterns.
In a method of forming an interlayer film according to the second aspect of the present invention, an undercoating film is formed in advance which affects to reduce fluidity of a portion of the interlayer film to be formed thereon, by which the portion of the interlayer film is deposited with an almost uniform thickness regardless of any pattern width on the substrate. Then, using the same source material, the rest portion of the film is deposited over the above portion of the film under a condition of providing the rest portion of the film with relatively increased fluidity.


REFERENCES:
patent: 5424253 (1995-06-01), Usami et al.
patent: 5665643 (1997-09-01), Shin
patent: 5683940 (1997-11-01), Yahiro
patent: 5691247 (1997-11-01), Lavie et al.
patent: 5700720 (1997-12-01), Hashimoto
patent: 5703404 (1997-12-01), Matsuura
patent: 404158551A (1992-06-01), None

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