JPH02121328A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To strengthen the bonding power on the polycrystalline silicon/silicide interface for preventing the release from occurring by a method wherein, after doping the polycrystalline silicon with an impurity, a natural oxide film is etched away within a silicide deposition device to deposit the silicide continuously without exposing it to the atmosphere. CONSTITUTION:After forming a gate oxide film on a silicon substrate, a polycrystalline silicon film 3 is deposited to be doped with an impurity however, a spontaneous oxide film 4 is deposited on the polycrystalline silicon. This natural oxide film 4 causing the release of silicide shall be removed. Thus, the spontaneous oxide film is removed within a silicide depositing device to deposit the silicide continuously without exposing it to the atmosphere. In order to remove the spontaneous oxide film 4, HF vapor is suitable but carbon halogenide, sulfur base gas are also applicable. The polycide gate thus formed having the high bonding power on the polycrystalline silicon/cilicide interface shall be subjected to no release at all even after the later heat treatment and oxidization processes.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is a highly integrated, high-speed VLS using polycide technology.
This invention relates to a method for producing I.

[Summary of the Invention] The present invention is based on two materials: polycrystalline silicon and high melting point metal silicide.
In polycide gate technology, which forms a gate electrode with a layered film, in order to prevent the growth of a natural oxide film due to the atmosphere on the polycrystalline silicon film, after doping the polycrystalline silicon with phosphorus, natural oxidation is performed in the same device and chamber. Membrane etching,
By continuously depositing high melting point metal dinoside, peeling between polycrystalline silicon and silicide is suppressed.

[Prior art] Conventionally, polycide was formed by first doping polycrystalline silicon with phosphorus using POCffl, etching the PSG grown there by wet cleaning, and then setting it in a silicide deposition device. .

A conventional method for forming polycide will be explained using FIGS. 2(a) to 2(C). FIG. 2(a) shows gate oxidation 1! on a silicon substrate 1! ! 2 is formed, polycrystalline silicon 3 is deposited thereon, and phosphorus is doped using pocg3 to form P.
It is a diagram showing SG etched by wet cleaning. Thereafter, as shown in FIG. 2(b), it was set in a silicide deposition apparatus, silicide was formed, and the next step was carried out. (Figure 2 (C)) [Problem to be solved by the invention] However, water washing after wet etching of PSG,
As shown in Figure 2, a natural oxide film grows on polycrystalline silicon during drying and further transport to the silicide deposition equipment.
a) This natural oxide film is.

This weakens the adhesion between polycrystalline silicon and silicide, making it easy to peel off at the polycrystalline silicon/silicide interface due to heat treatment in a post-process, etc. (FIG. 2(c)).

About washing and drying wet etching.

As the degree of integration progresses, the pattern becomes finer, and the difference in level becomes more severe, undried areas are more likely to form, and this problem becomes more serious.

[Means for Solving the Problems] In order to solve the above problems, in the present invention, after doping polycrystalline silicon, the natural oxide film is etched in a silicide deposition apparatus, and the silicide film is removed without being exposed to the atmosphere. Continuously deposited.

[Effect] By taking the above measures, the adhesive force at the polycrystalline silicon/silicide interface was strengthened and peeling could be prevented.

[Example] Figures 1(a) to 1(d) show cross-sectional views in the order of steps of an example according to the present invention. Figure 1(a) shows a process in which a gate oxide film is formed on a silicon substrate and a polycrystalline silicon film is formed. FIG. 3 is a diagram showing a state where the film is deposited and doped with impurities. A native oxide film grows on polycrystalline silicon, especially in pocI2. This is noticeable when phosphorus bridle deposition is used as a doping method. This is because the formed PSG is removed by wet etching and then washed with water, and because the phosphorus concentration is high, an oxide film tends to grow. However, even when doping is performed by ion implantation, even when doping with impurities other than phosphorus, the growth of a native oxide film cannot be avoided, even if the dose is reduced, although there is a difference in film thickness. This will cause the silicide to peel off, so it must be removed.

Further, after removal, the next silicide must be deposited without growing a native oxide film.

Therefore, in order to remove the natural oxide film in a silicide deposition device, we deposit silicide continuously without exposing it to the atmosphere (Fig. 1 (c)). , HF steam is suitable, but halogenated carbon, sulfur-based gases may also be used, silicide is WSia,
Polycide gates formed as described above, which are effective against high melting point metal silicides such as Ta5it, Mo5it, and TiSi*, have strong adhesion at the polycrystalline silicon/silicide interface, making subsequent heat treatment and oxidation processes difficult. No peeling occurs even after a long period of time (Fig. 1(d)).

[Effects of the Invention] As described above, in the polycide gate process, the natural oxide film on the underlying polycrystalline silicon is removed before silicide is deposited, and then the silicide is deposited in the same equipment without exposing it to the atmosphere. By continuously depositing the silicide film, it was possible to prevent the silicide film from peeling off.

[Brief explanation of the drawing]

FIGS. 1(a) to 1(d) are cross-sectional views of the manufacturing method according to the present invention in the order of steps, and FIG. 2 is a cross-sectional view of the conventional manufacturing method in the order of steps.・Semiconductor substrate ・Gate oxide film ・Polycrystalline silicon film ・Natural oxide film ・Silicide film Applicant: Seiko Electronic Industries Co., Ltd. Patent attorney: Keisuke Hayashi PJ i Figure Conventional C'') Manufacturing 7f Liquor production process order number?

Claims (1)

[Claims] forming a gate oxide film on a semiconductor substrate; depositing a polycrystalline silicon film on the gate oxide film; doping the polycrystalline silicon film with impurities;
A method for manufacturing a semiconductor device, comprising a step of etching a natural oxide film grown on the polycrystalline silicon film, and a step of depositing a high melting point metal silicide in the same device or room as the etching without being exposed to the atmosphere.