Semiconductor device manufacturing: process – Coating of substrate containing semiconductor region or of... – By reaction with substrate
Reexamination Certificate
2001-10-02
2003-09-09
Everhart, Caridad (Department: 2825)
Semiconductor device manufacturing: process
Coating of substrate containing semiconductor region or of...
By reaction with substrate
C438S585000, C438S660000, C438S782000
Reexamination Certificate
active
06617260
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a manufacturing method of a semiconductor device and, more particularly to a manufacturing method of a semiconductor device in which a wiring layer composed of a metal film is formed on an interlayer insulating film.
2. Description of the Related Art
Large scale integrated circuits (LSIs) known as the representative of the semiconductor devices can roughly be classified into memory products and logic products. Together with the progress of manufacturing technologies of semiconductor devices in recent years, the development, especially in the former, is remarkable. The semiconductor memories are classified into dynamic random access memories (DRAMS) and static random access memories (SRAMS). Since it is possible in the DRAM to take more extensive advantage of high degree of integration than in the SRAM and hence realize more cost reduction than in the SRAM, it is being applied widely to various kinds of memory devices in information equipment or the like.
In a DRAM, one memory cell is constituted by a memory cell transistor composed of a metal oxide semiconductor (MOS) transistor performing switching operation, and a capacitor connected to one diffusion region of the memory cell transistor, and information is stored by the memory cell as electrical charges into the capacitor. Here, in the DRAM, information to be written is transformed to the capacitor via the memory cell transistor from a bit line connected to the other diffusion region of the memory cell transistor, and information stored in the capacitor is read out there from via the transistor to the bit line. The bit line which serves as the path for writing and reading information is thus required to be in resistance as small as possible, for the purpose of increasing the operation speed. In recent years, therefore, a tungsten (W) film which has been used preferentially. The W film is formed as a bit line as a bit line on an interlayer insulating film and connected to the cell transistor through a contact hole provided in the interlayer insulating film.
It has been, however, observed that the W film often peels off from the interlayer insulating film occurs.
In order to remove such drawback, the Japanese Laid Open, (Kokai) Patent Publication Hei 9-289247 proposed an improved method of producing a DRAM. The description will be now made on such method with reference to
FIGS. 10A
to
10
D.
As shown in
FIG. 10A
, after formation of wiring layers
52
each consisting of a polycide and an aluminum alloy containing a slight amount of metal such as copper on an insulating film
51
, a silicon oxide film
53
as an interlayer insulating film is formed on the wirings
52
by a high density plasma chemical vapor deposition (HDP-CVD) method. Next, as shown in
FIG. 10B
, the silicon oxide film
53
is flattened by chemical mechanical polishing method.
Next, as shown in
FIG. 10C
, contact holes
54
are formed in the silicon oxide film
53
by photolithography.
In the conventional method, wiring material was deposited just after the formation of the contact holes. However, when a W film as the wiring material was deposited, the W film peeled off from the interlayer insulating film during the deposition of the W film. This is because gases such as hydrogen and argon confined in the silicon oxide film
53
as the interlayer insulating film were degassed and pushed up the W film during the deposition of the W film at a temperature of about 400° C.
Therefore, just after the formation of the contact holes
54
in
FIG. 10C
, gases such as hydrogen and argon held in the silicon oxide film
53
are degassed by subjecting the wafer to an annealing in a nitrogen atmosphere at a temperature in the range of 350 to 450° C. (degrees Centigrade) for 60 min.
Next, as shown in
FIG. 10D
, after forming an adhesion layer
55
consisting of Ti/TiN by sputtering or the like, a W film
56
is formed by a chemical vapor deposition (CVD).
According to this method, by subjecting the wafer to an annealing at a temperature in the range of 350 to 450° C. prior to the formation of the W film, it is possible to remove (degas) gases such as hydrogen and argon confined in the silicon oxide film
53
during formation of the silicon oxide film
53
by the HDP-CVD, so that there take place no such degassing at formation of the W film
56
. Accordingly, this prior art claims that there will not occur peeling of the W film
56
due to push of gases at the degassing.
Although it is not described in the above prior art, the W film needs to be patterned to wirings after the process of FIG.
10
D. When a metal film such as aluminum is used as wirings, the metal film can be patterned employing a resist film as a mask. However it is not appropriate that a resist film is employed as a mask for patterning the W film because it is not possible to obtain a sufficient selectivity between the resist film and the W film. Therefore, a silicon nitride film is used as a mask for patterning the W film.
It was found by the present inventor that when the silicon nitride film as the mask for patterning the W film is formed after formation of the W film according to the method in the above prior art, the W film actually peels off from the interlayer insulating film. Since it is difficult that the silicon nitride film is formed in low temperature when a thermal reaction is employed, the silicon nitride film is usually formed in temperature range of 700 to 750° C. When the wafer is subjected to a heat treatment at such high temperature after formation of the W film, gases including oxygen which have been confined in the interlayer insulating film are degassed to the outside, and the adhesion of the W film to the interlayer insulating film is aggravated due to oxidation of the W film by the gases including oxygen. Moreover, it was found that gases including oxygen held in the interlayer insulating film is scarcely desorbed at a temperature in the range of 350 to 450° C., and these gases are desorbed in a large quantity at higher temperatures than in the quoted range. In the above prior art, the heat treatment in the quoted temperature range is performed for the sole purpose of preventing peeling due to push-up of the W film caused by degassing of hydrogen or argon, and it utterly lacks the recognition as to the peeling problem caused by the degassing of gases including oxygen from the interlayer insulating film. As a result, according to the manufacturing method disclosed in the above prior art, gases including oxygen are held in large quantity in the layer insulting film even after an annealing at a temperature in the range of 350 to 450° C., and if the wafer is subjected to a heat treatment at a higher temperature, the W film will be oxidized by the degassing of gases including oxygen and will be peeling off from the interlayer insulating film.
SUMMARY OF THE INVENTION
The object of the present invention which was motivated by the above circumstance is to provide a manufacturing method of a semiconductor device capable of preventing the peeling of the W film caused by the gases including oxygen held in the interlayer insulating film even if the wafer is subjected to a heat treatment at higher temperatures after formation of the W film.
The method according to the present invention includes forming an insulating film over a semiconductor substrate, oxygen being introduced into the insulating film during formation of the insulating film, removing the oxygen from the insulating film to provide an oxygen-removed insulating film, and forming a metal film on the oxygen-removed insulating.
The removing the oxygen is performed by an annealing treatment.
The annealing treatment is performed at a temperature which is not lower than a heat treatment which may be carried out in a later step than formation of said metal film.
The later step includes forming a silicon nitride film over the metal film.
The insulating film is formed of a CVD silicon oxide film.
Moreover, the method according to the invention include
Abe Takayuki
Den Yasuhide
Everhart Caridad
NEC Electronics Corporation
Young & Thompson
LandOfFree
Method of manufacturing semiconductor device prevented from... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method of manufacturing semiconductor device prevented from..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method of manufacturing semiconductor device prevented from... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3111844