JP2000091556A - Electrode/wiring film, and semiconductor device using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent abnromal oxidation of a WSix film surface an enable low resistance by mainly containing grains with c-axis orientation in a WSix film. SOLUTION: A gate oxide film 2, a polycrystalline silicon film 3 and a WSix film (c-axis orientation WSix film) 4 mainly containing grains with c-axis orientation are laminated one by one in a gate electrode, and a cover film 5 formed of SiO2 is further formed on the WSix film 4. The ratio of Si constituting the WSix film 4 with respect to W (Si/W composition ratio) is 2.7 or less in composition ratio, and desirably about 2.0. That is, after the gate oxide film 2 and the polycrystalline silicon film 3 are formed one by one through a normal semiconductor process, the WSix film 4 is formed by sputtering and the cover film 5 formed of SiO2 is formed by a CVD method. Thereby, a WOx film is not formed by abnormal oxidation in the surface of the WSix film 4, and a flat WSix film 4 is formed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrode or a wiring film provided in a semiconductor device or the like and a semiconductor device using the same.

[0002]

In general, a gate electrode provided in the semiconductor device is schematically composed of a WSi _x film and the polycrystalline silicon. Incidentally, characteristics required for the gate electrode include low resistance and excellent heat resistance. The resistance of the gate electrode has been a can be realized by reducing the proportion (Si / W composition ratio) for W of Si constituting the WSi _x film, in this case, "Japan Journal Apuraizu Physics 35
Vol. 2A ", pages 584 to 588 (199
There is a problem that abnormal oxidation in WSi _x film surface as described in published 1994) occurs.

[0003] Figure 7 is a cross-sectional schematic view of a conventional gate electrode using the WSi _x film having a small ratio W of Si. FIG. 8 is a transmission electron micrograph showing the structure of a crystal constituting each film or layer constituting the conventional gate electrode of FIG. The conventional gate electrode shown in FIG.
1, a gate oxide film 12, a polycrystalline silicon film 13,
They are laminated in this order Si _x film 14, further the WSi _x film 14
A cover film 15 made of SiO ₂ is formed thereon.

[0004] However, in the WSi _x film 14 is a gate electrode provided with a reduced ratio W of Si, W deposited on the WSi _x film 14 surface abnormal oxidation (irregularities) by a heat treatment process, FIG. 7 to as shown in FIG. 8, WO _x layer 16 near the interface between the cover film 15 and the WSi _x film 14 made of SiO ₂ will be incorporated. This W
O _x layer 16, since as it has conductivity and volatility, and penetrates into cover film 15, as shown in FIG. 7, therefore, WSi _x film in which such abnormal oxidation occurred 1
By applying 4 to actual semiconductor device, there is a problem that occurs electric short circuit between contacts adjacent to the gate electrode using the WSi _x film 14.

Accordingly, usually WSi _x film Si / W composition ratio resistance value enough not to impair the device characteristics can be obtained is 2.7 or more is used. In addition, "Japan Journal Applied Physics 35
Part 1, No. 2A ", pp. 584-588 (199
As described in published 1994), in the Si / W composition ratio of 2.0 or more WSi _x film, by eliminating the supply of oxygen in a heat treatment process at a low temperature of up to 600 ° C., WSi _x film 14 suppresses the abnormal oxidation of W deposited on the surface, WSi _x film 14 diffusion of Si by rate limiting the in WS
i _x film 14 after forming a thin SiO ₂ film on the surface, 600
Supplying oxygen during the heat treatment process at a high temperature of at least
By forming the cover film 15 made of SiO ₂ , abnormal oxidation of W is prevented.

[0006]

However, in recent years,
There is an increasing demand for further miniaturization of the electrodes and wirings of LSIs. For this purpose, it is necessary to further reduce the resistance of the electrodes and wirings, and the Si / W composition ratio is smaller than 2.7, that is, the ratio of W Must be increased, in which case,
It will promote abnormal oxidation of the above such WSi _x film 14 surface. In addition, it is practically difficult to supply oxygen during the heat treatment process at a high temperature of 600 ° C. or more as described above to form the cover film 15 made of SiO _2. Even in the process, a very small amount of oxygen cannot be avoided, and the number of man-hours in the semiconductor process is increased, which causes a problem of lowering the yield. Further, without forming a thin SiO ₂ film is WSi _x film 14 surface, directly, in the case of forming a cover film 15 made of SiO _2, the cover layer 15 is intended to be formed in a conventional CVD method, to Oxygen is contained in the necessary source gas. Therefore, when forming the cover film 15, the supply of oxygen always occurs, so that it is difficult to suppress oxygen and it is difficult to avoid abnormal oxidation of W.

[0007] The present invention can prevent the abnormal oxidation of the WSi _x film surface which has been made in view of the above circumstances, to obtain an electrode-wiring film provides low resistance, further comprising such an electrode and wiring film it allows to provide a semiconductor device with no electrical short-circuit failure due to abnormal oxidation of the WSi _x film surface.

[0008]

The present inventors SUMMARY OF THE INVENTION may, WSi _x film can prevent the abnormal oxidation of the surface, to provide an electrode-wiring film provides low resistance, in particular the crystal grains constituting the WSi _x film ( focusing on grain), as a result of various studies and experiments, the crystal orientation of the grains, and the degree of abnormal oxidation of the WSi _x film surface is correlated, in particular, c-axis oriented in the WSi _x film When mainly containing grains having properties, W
To investigate the ability to prevent the abnormal oxidation of the Si _x film surface and was completed the present invention.

[0009] That is, the invention of claim 1, the electrode-wiring film characterized by using the WSi _x film containing mainly grains having a c-axis orientation was means for solving the above-described problem. The invention of claim 2 is the solution to the electrode-wiring film according to claim 1, wherein the ratio W of the Si constituting the WSi _x film is characterized in that 2.7 or less in the composition ratio of the above objects Means.

According to a third aspect of the present invention, at least an oxide film, a polycrystalline silicon layer, a WSi
_x film, a semiconductor device having an oxide film provided at least sequentially laminated comprising electrodes, c as the WSi _x film
A semiconductor device characterized by WSi _x film containing mainly grains having an axial orientation was used was solution to the above problem. The invention of claim 4 is the semiconductor device at least WSi _x film are laminated wiring is provided at least on the oxide film mainly containing grains wherein having a c-axis orientation as WSi _x film a semiconductor device characterized by WSi _x film was used was solution to the above problem. Further, the invention according to claim 5 is characterized in that at least an oxide film, a polycrystalline silicon layer, a WSi
_x film, an electrode oxide film is formed by sequentially stacking, grains having a semiconductor device wiring and is provided at least with a WSi _x film, a c-axis orientation as WSi _x film of the electrode and / or wiring the semiconductor device according to claim primarily that WSi _x film containing was used was used as a means for solving the above-described problem. The invention of claim 6, constitutes a WSi _x film containing mainly grains having the c-axis orientation S
The semiconductor device according to claim 3, wherein the ratio of i to W is 2.7 or less in composition ratio.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the electrode / wiring film and the semiconductor device of the present invention will be described in detail. FIG.
FIG. 1 is a schematic sectional view showing a first embodiment in which an electrode / wiring film of the present invention is applied to a gate electrode. FIG. 2 is a transmission electron micrograph showing the structure of a crystal constituting each film or layer constituting the gate electrode of FIG. The gate electrode of the first embodiment, on the Si substrate 1, a gate oxide film 2, the polysilicon film 3, c-axis mainly containing grains having an orientation WSi _x film (c-axis oriented WSi _x Film) 4 in this order,
Cover film 5 made of SiO ₂ addition on the WSi _x film 4
Are formed. Ratio W of the Si constituting the WSi _x film 4 (Si / W composition ratio) is 2.7 or less in the composition ratio, preferably about 2.0.

In the method of manufacturing a gate electrode according to the first embodiment, a gate oxide film 2 and a polycrystalline silicon film 3 are sequentially formed on a Si substrate 1 by an ordinary semiconductor process,
The grains having an axial orientation contain mainly, Si / W composition ratio of 2.7 or less, WSi _x film 4 is preferably 2.0
Is formed by a sputtering method, and SiO _{2 is} formed by a CVD method.
Is formed. The heating temperature for forming the cover film 5 is preferably set to about 700 ° C.

[0013] Figure 3, WSi _x provided in the gate electrode
3 shows the results of X-ray diffraction analysis of the grain orientation in the film.
In Figure 3, is an X-ray diffraction results of analysis of the grain orientation of the WSi _x film provided on the gate electrode of the first embodiment, is provided in the conventional gate electrode shown in FIG. 7 the grain orientation in the WSi _x film is an X-ray diffraction results of the analysis.

[0014] In the gate electrode of the first embodiment of the above-described structure, as can be seen from the transmission electron micrograph shown in FIG. 2, the WSi _x film 4 surface formation of WO _x film due to abnormal oxidation it can be seen that the formed flat WSi _x film was not seen. This is because, as seen from the X-ray diffraction results of the grain orientation in the WSi _x film 4 shown in FIG. 3, WSi _x film 4 in grains provided to the gate electrode of the first embodiment shown in FIG. 7 It was like as compared with conventional grain orientation in the WSi _x film 14 provided on the gate electrode (0
02) The c-axis oriented X-ray intensity in the direction is strong, that is, WSi
It can be seen that the x film 4 is mostly composed of grains with c-axis orientation. Further, WSi _x film 4 composed of such c-axis oriented grains, even at low Si / W composition ratio was achieved high heat resistance.

In the gate electrode of the first embodiment,
By using the WSi _x film 4 mainly containing grains having a c-axis orientation, even as small as 2.7 or less at a ratio W of the Si constituting the WSi _x film 4 composition ratio,
WSi _x film surface deposited W is prevented from abnormally oxidized by heat treatment, it is possible to lower resistance. Also, WSi
_x To prevent abnormal oxidation of W deposited on the film surface,
It is not necessary to suppress the supply of oxygen in the heat treatment step at a low temperature of 00 ° C. or lower, and the yield of the semiconductor process is improved.

Next, a second embodiment of the electrode / wiring film of the present invention will be described. FIG. 4 is a schematic sectional view showing a second embodiment in which the electrode / wiring film of the present invention is applied to a wiring. FIG. 5 is a transmission electron micrograph showing a structure of a crystal constituting each film or layer constituting the wiring of FIG. The wiring according to the second embodiment is such that an SiO ₂ film (oxide film) is formed on a Si substrate 1.
8. WSi mainly containing grains having c-axis orientation
_{An x} film 4 and a cover film 5 made of SiO ₂ are sequentially laminated.

The method for manufacturing a wiring according to the second embodiment is as follows.
After the SiO ₂ film 8 is formed on the Si substrate 1 by a normal semiconductor process, the Si 2 mainly contains grains having c-axis orientation under the same process conditions as the gate electrode of the first embodiment described above. / W composition ratio is 2.7 or less, preferably a WSi _x film 4 is 2.0 is formed by sputtering method to form a cover film 5 made of SiO ₂ by CVD. The heating temperature for forming the cover film 5 is preferably set to about 700 ° C.

[0018] In the wiring of the second embodiment of the above-described structure, as can be seen from the transmission electron micrograph shown in FIG. 5, the WSi _x film 4 surface with that of the first embodiment WO _x by similarly abnormal oxidation and WSi _x film 4 which is
Formation of film it can be seen that the flat WSi _x film not seen is formed.

[0019] In the wiring of the second embodiment, by using the WSi _x film 4 mainly containing grains having a c-axis orientation, the ratio W of the Si constituting the WSi _x film 4 Composition Even if the ratio is as small as 2.7 or less, WSi
_It is possible to prevent W deposited on the _x film surface from being abnormally oxidized by the heat treatment, and it is possible to reduce the resistance. Further, in order to prevent the abnormal oxidation of W precipitated in WSi _x film surface, 600 ° C.
It is not necessary to suppress the supply of oxygen in the following heat treatment process at a low temperature, and the yield of the semiconductor process is improved. It is to be noted that the first of the above, in the second embodiment, the WSi _x film electrode-containing mainly grains having a c-axis orientation
Although the case where it is used for wiring has been described, it goes without saying that the same effect can be obtained when it is used for other purposes.

Next, an embodiment of the semiconductor device of the present invention will be described. FIG. 6 is a schematic sectional view showing an embodiment of the semiconductor device of the present invention. In the semiconductor device of this embodiment, a gate oxide film 2, a polycrystalline silicon film 3, and a W mainly containing grains having c-axis orientation are formed on a Si substrate 1.
Si _x film and (c-axis oriented WSi _x film) 4 of the gate electrode formed by laminating in this order (the electrode of the embodiment of the present invention), an interlayer insulating film 9 on the gate electrode, a polycrystalline silicon wiring layer 10, c-axis formed by laminating main embodiment of the wiring film (c-axis oriented WSi _x wiring film) made of WSi _x film present invention containing 24, a cover film 5 made of SiO ₂ sequentially grains having an orientation is there. Reference numeral 32 in the figure denotes a contact portion 32 adjacent to the gate electrode.

[0021] In the semiconductor device of the embodiment is provided with the electrode and the wiring film embodiments of the present invention, WSi _x film used for these intended mainly containing grains having a c-axis orientation because, no abnormal oxidation of the WSi _x film 4, an electrical short failure of the contact portion 32 adjacent to the gate electrode can be prevented. Also, the wiring film 2
As for No. 4, a favorable wiring film can be formed without abnormal oxidation.

[0022]

According to the electrode-wiring film of the present invention as described in the foregoing, by using the WSi _x film containing mainly grains having a c-axis orientation, abnormal oxidation of the WSi _x film surface Can be prevented, and the resistance can be reduced. Also, WSi
_x To prevent abnormal oxidation of W deposited on the film surface,
It is not necessary to suppress the supply of oxygen in the heat treatment step at a low temperature of 00 ° C. or lower, and the yield of the semiconductor process is improved. Further, according to the semiconductor device of the present invention, by having the electrodes and / or wiring film of the present invention, good electrical characteristics without electrical short-circuit failure due to abnormal oxidation of the WSi _x film surface obtained .

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing a first embodiment in which an electrode of the present invention is applied to a gate electrode.

FIG. 2 is a transmission electron micrograph showing a structure of a crystal constituting each film or layer constituting the gate electrode of FIG.

3 is a diagram showing an X-ray diffraction results of the analysis of grain orientation in the WSi _x film provided on the gate electrode.

FIG. 4 is a schematic sectional view showing a second embodiment in which the electrode / wiring film of the present invention is applied to a wiring.

5 is a transmission electron micrograph showing a structure of a crystal constituting each film or layer constituting the wiring of FIG. 4;

FIG. 6 is a schematic sectional view showing an embodiment of the semiconductor device of the present invention.

[7] WSi has a small percentage of the W of the Si _x
FIG. 9 is a schematic cross-sectional view showing a conventional gate electrode using a film.

8 is a transmission electron micrograph showing a structure of a crystal forming each film or layer constituting the conventional gate electrode of FIG. 7;

[Explanation of symbols]

1 ... Si substrate, 2 ... Gate oxide film, 3 ... Polycrystalline silicon film, 4 ... WSix film (c-axis oriented WSix)
Film), 5 ... cover film, 8 ... SiO ₂ film (oxide film), 9 ... interlayer insulation film, 10 ... polycrystal silicon wiring layer, 24 ... wiring layer (c-axis oriented WSix wiring film), 32 ... contact part.

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4M104 AA01 BB01 BB37 BB38 CC05 DD37 DD79 HH16 5F033 AA04 BA02 BA24 BA33 BA37 BA46

Claims (6)

[Claims] 1. A electrode and wiring film characterized by using the WSi _x film containing mainly grains having a c-axis orientation. Wherein said WSi _x film ratio W of the Si constituting the is characterized in that 2.7 or less composition ratio claim 1, wherein the electrode-wiring film. 3. An oxide film on a silicon substrate,
Polycrystalline silicon layer, WSi _x film, a semiconductor device having an oxide film provided at least the electrode formed by sequentially stacking, WSi _x film containing mainly grains having a c-axis orientation as the WSi _x film using A semiconductor device, comprising: 4. A semiconductor device in which at least WSi _x film are laminated wiring is provided at least on the oxide film, WSi _x film containing mainly grains having a c-axis orientation as the WSi _x film A semiconductor device characterized by being used. 5. At least an oxide film on a silicon substrate,
Polycrystalline silicon layer, WSi _x film, c-axis and an electrode oxide film are sequentially stacked, in a semiconductor device in which wiring and is provided at least with a WSi _x film, as WSi _x film of the electrode and / or wiring wherein a the WSi _x film containing mainly grains having an orientation is used. 6. The method of claim 3 or 4, wherein the ratio W of the Si constituting the WSi _x film containing mainly grains having the c-axis orientation is 2.7 or less in the composition ratio Or the semiconductor device according to 5.