JPH08306913A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE: To avoid the mutual diffusion through silicide layer of impurities doped in a polysilicon by checking the release of tungsten silicide or abnormal oxidation in a tungsten polycide electrode used for CMOS structure. CONSTITUTION: After the formation of a gate oxide film 2 and then a polysilicon film 3 on a silicon substrate to be turned into n<+> polysilicon by impurity implantation on a silicon substrate 1, a tungsten silicide 4 is formed by sputtering step on the polysilicon film 3. Next, the second SiO2 film (barrier layer) is formed by implanting oxygen ions in the part of the polysilicon film 3 by oxygen implantation. Finally, after cleaning up the surface, a gate electrode made of the tungsten silicide 4, the second SiO2 film 5, the polysilicon film is formed by polysilicon etching step.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a semiconductor device, for example, a method for manufacturing a semiconductor device which can be effectively applied to a complementary MOS device or a static RAM having a memory cell structure having a high resistance polysilicon as a load. It is a thing.

[0002]

2. Description of the Related Art With the recent rapid development of the semiconductor industry,
There is an increasing demand for higher speed semiconductor devices.
In semiconductor devices, the most effective means to cope with high speed is to use high melting point metal with low resistance value instead of polycrystalline silicon film (polysilicon film) which has been used as gate electrode or wiring material. It is to be. Tungsten silicide is most widely used as this metal.

However, since the tungsten silicide film itself has poor adhesion to the underlying gate oxide film, a structure in which it is overlapped with the polysilicon film is predominant. A problem with the above-mentioned tungsten polycide film is that peeling may occur in the tungsten silicide film in the thermal process after the formation of the tungsten polycide film. The cause of this peeling is that (1) the crystal grain size of the tungsten silicide increases due to the heat step, and the adhesion to the underlying polysilicon film deteriorates, and (2) O ₂ in the furnace atmosphere.
It is conceivable that the tungsten is oxidized by this and the film composition is changed to deteriorate the adhesion. As a measure for preventing this peeling, it is considered that after the tungsten silicide film is formed, the tungsten silicide layer is made amorphous by implanting N ⁺ ions and the surface layer is nitrided.

Further, an n-channel MO is formed on the same semiconductor substrate.
In a CMOS device in which an integrated circuit including an SFET and a p-channel MOSFET is formed, an nMO gate electrode is formed of n-type polysilicon, and a pMOS gate electrode is formed of p-type polysilicon.
CMOS devices have been proposed in which both S and pMOS have a surface channel type MOS structure. In this structure, when the n-type and p-type polysilicon has a polycide gate electrode in which silicide is laminated, the silicide film has a high impurity diffusion rate, so that the silicide is laminated on the impurity-doped polysilicon. When the heat treatment is performed, there is a problem that the impurities in the n-type polysilicon and the impurities in the p-type polysilicon interdiffuse through the silicide layer near the connection portion of the gate wiring.
As a measure for preventing this, a barrier layer (for example, Ti) that prevents diffusion at the interface between polysilicon and silicide is used.
It is considered to stack N).

[0005]

However, when the tungsten polycide film in which N ⁺ ions are implanted into the tungsten silicide film is used for the CMOS structure, abnormal oxidation and peeling can be prevented, but mutual diffusion cannot be prevented. Further, if a barrier layer is stacked on the interface between the polysilicon and the silicide layer to prevent mutual diffusion, the silicide layer may be easily peeled off.

The present invention has been made in view of the above problems, and an object thereof is to prevent peeling and abnormal oxidation of a tungsten silicide film in a tungsten polycide electrode used for a CMOS structure, and further to dope into polysilicon. An object of the present invention is to provide an electrode forming method capable of preventing mutual diffusion of impurities through a silicide layer.

[0007]

According to a first aspect of the present invention, there is provided a method of manufacturing a semiconductor device, wherein a polysilicon film used as a gate electrode or wiring of a field effect transistor and a refractory metal silicide film are formed on a semiconductor substrate. After stacking in order,
It is characterized in that a step of implanting oxygen ions into the refractory metal silicide film is provided.

According to a second aspect of the present invention, in the method of manufacturing a semiconductor device according to the first aspect, in the oxygen ion implantation step, a projected range in the refractory metal silicide is Rp and a film thickness of the refractory metal silicide is T. At this time, the oxide film is formed at a position inside the polysilicon rather than at the interface between the polysilicon and the refractory metal silicide by performing the implantation energy satisfying the inequality Rp> T.

According to a third aspect of the present invention, in the method of manufacturing a semiconductor device according to the second aspect, the resist is patterned so that a portion where oxygen ions are implanted and a portion where oxygen ions are not implanted are formed before the oxygen ion implantation step. And a photolithography step of

A method of manufacturing a semiconductor device according to a fourth aspect is the dual gate C according to the method of the third aspect.
A method of manufacturing a MOS, comprising n-type polysilicon and p
The method is characterized by including a photolithography step of patterning a resist so that oxygen ions are implanted only in the junction of the mold polysilicon.

According to a fifth aspect of the present invention, there is provided a semiconductor device manufacturing method, wherein nitrogen ions are implanted in place of oxygen ions in the second, third, or fourth manufacturing method to replace the oxide film with a nitride film. Is formed.

[0012]

Embodiments of the present invention will be described below with reference to the drawings. Example 1 FIGS. 1A to 1D are cross-sectional views of a semiconductor device, which sequentially show manufacturing steps of the semiconductor device. First, as shown in FIG. 1A, a gate oxide film (SiO 2) is formed on a silicon substrate 1.
₂ film 2 is formed to a thickness of about 110Å, and a polysilicon film 3 is formed to a thickness of about 2000Å on the gate oxide film 2. Then, impurities are implanted or doped to obtain n ⁺ or p ⁺ polysilicon. Furthermore, FIG.
As shown in (b), the tungsten silicide 4 is formed on the polysilicon film 3 to a thickness of about 25 by, for example, a sputtering method.
00Å Form. After forming the tungsten silicide 4,
As shown in FIG. 1C, a _second SiO ₂ film (or SiN film) 5, that is, a barrier layer, is formed at a position inside the polysilicon film 3 rather than at the interface between the polysilicon film 3 and the tungsten silicide 4. Injection energy, injection amount 1
Oxygen ions (or nitrogen ions) on the order of 0 ¹⁸ / cm ²
Inject. The surface was cleaned after ion implantation, and
As shown in (d), the tungsten silicide 4 and the second Si are formed by using the photolithography method and the etching method.
A gate electrode composed of the O ₂ film 5, the polysilicon film 3 and the gate oxide film 2 is formed.

In the above-described embodiment, after the tungsten silicide 4 is deposited, the _second SiO ₂ film (or SiN film) 5 is formed at a position inside the polysilicon film 3 beyond the interface between the polysilicon film 3 and the tungsten silicide 4. Therefore, the barrier layer for preventing mutual diffusion can be formed in a state where the tungsten silicide 4 is hard to peel off.
Also, the 2SiO ₂ film (or SiN film) 5 thin (e.g. 100Å or less) and forming, oxygen (or nitrogen) the 2SiO ₂ film formed by implantation (or SiN
Film) 5 by as compared to SiO ₂ film deposition is uneven, the 2SiO ₂ film (or SiN film) 5, a polysilicon film 3 and the tungsten silicide 4 can be formed without insulation.

[0014]

As is apparent from the above description, claim 1
In the method for manufacturing a semiconductor device described in (3), by implanting oxygen ions after forming the refractory metal silicide film (tungsten silicide), amorphization of the tungsten silicide layer is promoted, which causes rapid crystallization during the thermal process. Is suppressed and the grain size is reduced, so that the increase in stress of the tungsten silicide layer is suppressed and the adhesion with the base is maintained. In the method of manufacturing a semiconductor device according to claim 2, the oxide film is formed at a position inside the polysilicon rather than at an interface between the polysilicon and the tungsten silicide, so that the tungsten silicide is not peeled off. It is possible to prevent mutual diffusion of impurities therein. In the method for manufacturing a semiconductor device according to the third aspect, by forming the oxide film as the barrier layer locally rather than forming it on the entire surface, it is possible to prevent an increase in resistance of the polycide electrode while suppressing mutual diffusion. In the method of manufacturing a semiconductor device according to claim 4, the barrier layer is provided only at a junction portion of p-type and n-type polysilicon, which is a main location where mutual diffusion occurs, so that the resistance of the polycide electrode is suppressed while suppressing the mutual diffusion. You can prevent the increase. In the method for manufacturing a semiconductor device according to the fifth aspect, the same effect as that of the manufacturing method according to the second, third or fourth aspect can be obtained by implanting nitrogen ions.

[Brief description of drawings]

FIG. 1 is a sectional view of a semiconductor device according to an embodiment of the present invention.

[Explanation of symbols]

1 silicon substrate 2 gate oxide film 3 polysilicon film 4 tungsten silicide 5 _second SiO ₂ film (or SiN film)

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Mitsuhiro Oizumi 1-3-6 Nakamagome, Ota-ku, Tokyo Within Ricoh Co., Ltd.

Claims (5)

[Claims] 1. A high melting point metal silicide film after a polycrystalline silicon film (polysilicon film) used as a gate electrode or wiring of a field effect transistor and a high melting point metal silicide film are sequentially stacked on a semiconductor substrate. A method of manufacturing a semiconductor device, comprising the step of implanting oxygen ions into the semiconductor. 2. The oxygen ion implantation step is performed with implantation energy satisfying the inequality Rp> T, where Rp is a projected range in the refractory metal silicide and T is a film thickness of the refractory metal silicide. 2. The method for manufacturing a semiconductor device according to claim 1, wherein an oxide film is formed at a position inside the polycrystalline silicon rather than at an interface between the polycrystalline silicon (polysilicon) and the refractory metal silicide. . 3. The method according to claim 2, further comprising, before the oxygen ion implantation step, a photolithography step of patterning a resist so that a portion where oxygen ions are implanted and a portion where oxygen ions are not implanted are formed. Of manufacturing a semiconductor device of. 4. A method of manufacturing a dual-gate CMOS by the manufacturing method according to claim 3, wherein the resist is such that oxygen ions are implanted only into a junction between n-type polycrystalline silicon and p-type polycrystalline silicon. A method of manufacturing a semiconductor device, comprising: a photolithography step of patterning a semiconductor. 5. A semiconductor device according to claim 2, 3 or 4, wherein a nitrogen film is implanted in place of the oxygen ions to form a nitride film in place of the oxide film. Production method.