JPH0541362A - Manufacture of semiconductor device - Google Patents

Abstract

(57) [Abstract] [Purpose] Regarding a semiconductor device having electrodes and wirings having a laminated structure such as polycide, an electrode having a laminated structure which has a certain film thickness and satisfies the requirement of planarization in a later step,
An object is to provide a wiring structure. [Structure] A step of sequentially stacking a polycrystalline silicon film 3 and a refractory metal silicide film 4 on a semiconductor substrate 1, a step of patterning the refractory metal silicide film 4 and the polycrystalline silicon film 3 into an electrode shape, and patterning The refractory metal silicide film 4 and the polycrystalline silicon film 3 are heat-treated to form a polycide electrode 2 having a convex cross section.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure of a cover film of a semiconductor integrated circuit device and a manufacturing method thereof. With the recent trend toward higher integration and miniaturization of semiconductor devices, it is necessary to eliminate wiring delays in order to increase the processing speed in semiconductor devices, and it is required to reduce wiring resistance as much as possible.

Therefore, in place of the conventional polycrystalline silicon film wiring, a polycide structure wiring, which can reduce the wiring resistance, is generally used.

[0003]

2. Description of the Related Art FIG. 3 is an explanatory view of a conventional example. In the figure, 13 is a silicon (Si) substrate, 14 is a field silicon dioxide (SiO ₂ ) film, 15 is a gate SiO ₂ film, and 16 is polycrystalline silicon.
(Poly-Si) film, 17 is a tungsten silicide (WSi ₂ ) film,
18 is a polycide gate electrode, and 19 is a source / drain diffusion layer.

As shown in FIG. 3, electrodes and wirings of a conventional laminated structure are simply formed by laminating a silicide material such as a poly-Si film 16 and a WSi ₂ film 17, and a polycide electrode 18 is formed by heat treatment. Even at this time, in particular, deformation of the cross-sectional shape due to heat stress was not considered.

However, high integration of semiconductor devices in recent years,
Along with the miniaturization, if the electrode and wiring materials are not thinned, it will become difficult to flatten in the subsequent process.

[0006]

Therefore, in order to reduce the resistance of electrodes and wirings, it is necessary to have a certain thickness, and it is desired to reduce the film thickness in consideration of flattening in the subsequent process. There are demands and there is a trade-off (conflicting) relationship.

In order to solve the above problems, the present invention provides an electrode / wiring structure having a laminated structure having a small film thickness and a small aspect ratio in order to satisfy the requirement of flattening in a subsequent process. To aim.

[0008]

FIG. 1 illustrates the principle of the present invention. In the figure, 1 is a semiconductor substrate, 2 is a polycide electrode having a convex cross section, 3 is a poly-Si film, and 4 is a refractory metal silicide film.

As shown in FIG. 1, the wiring structure has a convexly curved cross section. The degree of curvature can be optimized depending on the growth conditions and film thickness when forming the laminated structure, and the heat treatment conditions and oxidation conditions in the subsequent process.

That is, an object of the present invention is to provide a method of manufacturing a semiconductor device in which a polycide electrode 2 having a convex cross section is formed on a semiconductor substrate 1. As shown in FIG. As shown in FIG. 1B, a step of sequentially laminating the polycrystalline silicon film 3 and the refractory metal silicide film 4 on the upper surface,
A step of patterning the refractory metal silicide film 4 and the polycrystalline silicon film 3 into an electrode shape, and FIG.
As shown in FIG. 3, the patterned refractory metal silicide film 4 and the polycrystalline silicon film 3 are heat-treated,
And the step of forming a polycide electrode 2 having a convex cross section.

[0011]

According to the present invention, the cross-sectional structure of the electrodes and wirings of the polycide structure is convexly curved by heat treatment after patterning the laminated electrodes. Therefore, even if the polycide film is thick to some extent, it can be flattened in a later step. In contrast, it has a very advantageous shape.

[0012]

FIG. 2 is a schematic sectional view in order of the steps of an embodiment of the present invention. In the figure, 5 is a Si substrate, 6 is a field SiO
₂ film, 7 is a gate SiO ₂ film, 8 is a poly-Si film, 9 is a WSi ₂ film, 1
0 is a polycide electrode with a convex cross section, 11 is a source / drain diffusion layer, and 12 is a cover PSG film.

An embodiment of the present invention will be described in the order of steps with reference to FIG. As shown in FIG. 2 (a), a poly-Si film 8 is formed on the Si substrate 5 on which a gate SiO ₂ film 7 having a thickness of 150 Å is formed by a normal method by a CVD method at a substrate temperature of 620
Silica (SiH ₄ ) gas of 150 sccm was used as a process gas at a temperature of 500 ° C and a vacuum of 0.2 Torr to coat a thickness of 500 Å.

Then, using a binary process gas of 400 sccm of SiH ₄ gas and 10 sccm of tungsten hexafluoride (WF6) gas, a poly-Si film 8 was formed under the conditions of a substrate temperature of 360 ° C. and a vacuum degree of 350 mTorr. A WSi ₂ film 9 is laminated on top of it to a thickness of 300 Å.

Next _{, as} shown in FIG. 2 (b), the WSi ₂ film 9 is anisotropically etched by the RIE method using the resist film as a mask to etch the WSi ₂ film 9 with chlorine (Cl ₂ ) gas at 60 sccm and a vacuum degree of 5 mTor.
Electrode shape was obtained by patterning the poly-Si film 8 under conditions of r, μ wave output 2 kW and RF output 70 W, then oxygen (O 2) gas 10 sccm, vacuum degree 5 mTorr, μ wave output 2 kW, RF output 70 W. Form.

Then, as shown in FIG. 2 (c), nitrogen (N
2) Heat treatment at 850 ° C for 60 minutes in a gas atmosphere to form a polycide electrode 10 with a convex cross section to form a gate electrode. Then, as shown in Fig. 2 (d), arsenic ions (As ⁺ ) were implanted by an ordinary method under the conditions of an accelerating voltage of 40 keV and a dose of 4x10 ¹⁵ / cm ² at 850 ° C.
Source / drain diffused layer
Forming 11.

As shown in FIG. 2E, the cover PSG film 12
To a thickness of 4,000Å.

[0018]

As a result, even if the film thickness of the gate electrode is slightly thick, the resistance is low because the cross section is convex (kamaboko).
Moreover, the aspect ratio is small, and a gate electrode can be formed on the cover PSG film 12 that does not cause any obstacle due to the step difference of the coating, which greatly contributes to the development of highly integrated semiconductor devices.

[Brief description of drawings]

FIG. 1 is an explanatory view of the principle of the present invention.

2A to 2C are schematic cross-sectional views in order of the processes of an embodiment of the present invention.

FIG. 3 is an explanatory diagram of a conventional example.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Semiconductor substrate 2 Polycide electrode having a convex cross section 3 Poly Si film 4 Refractory metal silicide film 5 Si substrate 6 Field SiO ₂ film 7 Gate SiO ₂ film 8 Poly Si film 9 WSi ₂ film 10 Polycide electrode having a convex cross section 11 Source / drain diffusion layer 12 Cover PSG film

Claims (1)

[Claims] 1. A method of manufacturing a semiconductor device, wherein a polycide electrode (2) having a convex cross section is formed on a semiconductor substrate (1), comprising: a polycrystalline silicon film (3) on the semiconductor substrate (1); A step of sequentially depositing a refractory metal silicide film (4), a step of patterning the refractory metal silicide film (4) and the polycrystalline silicon film (3) into an electrode shape, and the patterned refractory metal A method of manufacturing a semiconductor device, comprising a step of heat-treating the silicide film (4) and the polycrystalline silicon film (3) to form a polycide electrode (2) having a convex cross section.