KR960011639B1 - Formation of shallow-junction using titanium silicide - Google Patents

Abstract

An upper region of silicon substrate consists of a field oxide film, a gate oxide film, a gate electrode, and a spacer oxide film. The method comprises the steps of: using a multiple crystallization(6) as a diffusion source to form a shallow junction, evaporating titanium on the polysilicon(6), etching a silicide in hydrogen fluoride fluid after the reaction of multiple crystallization(6) and titanium(9).

Description

Thin junction formation method using titanium silicide

1A to 1E are cross-sectional views showing a method of forming a thin junction using polycrystalline silicon as a diffusion source.

2A to 2C are cross-sectional views showing a method of forming a thin junction using polysilicon as a diffusion source and using titanium silicide.

* Explanation of symbols for main parts of the drawings

1: silicon substrate 2: field oxide film

3: gate insulating film 4: polycrystalline silicon

5: spacer oxide film 6: polysilicon

7 ion implantation (As or BF ₂ ) 8 N ⁺ or P ⁺ diffusion layer

9: titanium 10: titanium silicide

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for forming a thin junction, which is essential for the manufacture of highly integrated semiconductor devices. The present invention relates to a method for selectively removing titanium silicide in a hydrogen fluoride solution by forming a titanium silicide by reacting with a titanium silicide and using an etching rate of titanium silicide in a hydrogen fluoride solution much larger than that of an oxide film.

The formation of thin junctions is essential to increase the degree of integration without degrading the performance of semiconductor devices. Therefore, various processes for forming thin junctions have been proposed, and among these processes, the thin junction formation method using polycrystalline silicon is considered to be the best method among the solid diffusion source methods.

However, the method of forming a thin junction using polycrystalline silicon has difficulty in removing it after using polycrystalline silicon as a diffusion source.

When using polycrystalline silicon as a diffusion source, in order to prevent short circuit between active region and gate, photosensitive film is used before or after ion implantation to leave polycrystalline silicon only in active region and to remove polycrystalline silicon on gate electrode and spacer oxide. At the same time, with the increase in the degree of integration of the device, such a method has been pointed out as a practical application problem because there is no process margin.

Therefore, all of the active region, the spacer oxide layer, and the gate electrode are deposited with polycrystalline silicon, followed by ion implantation and diffusion.

In this case, since the short circuit between the active region and the gate electrode is inevitable, the polycrystalline silicon used as the diffusion source should be removed.

However, at this time, since the polycrystalline silicon used as the diffusion source is deposited on the silicon substrate or the gate polycrystalline silicon, it is difficult to determine the point at which the etching should be completed, which may cause damage to the diffusion layer formed on the silicon substrate.

Therefore, in the present invention, after the diffusion is completed by using polycrystalline silicon, a certain thickness of titanium is deposited on the polycrystalline silicon, and after the heat treatment, the titanium silicide is formed and the silicon silicide is much larger than the etching rate of titanium silicide in the hydrogen fluoride solution. By selectively removing titanium silicide with hydrogen fluoride solution to achieve a thin junction.

According to the present invention, in order to form a thin junction, a step of forming a thin junction using polycrystalline silicon as a diffusion source and depositing a certain thickness of titanium on the polycrystalline silicon used as the diffusion source, and hydrogenated fluoride solution after titanium silicided through heat treatment And selectively removing titanium silicide from within.

Hereinafter, the present invention will be described in detail with reference to the drawings.

1A to 1E are cross-sectional views showing a method of forming a thin junction by the prior art.

FIG. 1A shows the growth of a field oxide film 2 and a gate oxide film 3 on the silicon substrate 1 to form a polycrystalline silicon 4 for the gate electrode, and to prevent a short circuit between the gate electrode and the active region. 18 is a cross-sectional view showing a state in which the spacer oxide film 5 is formed.

FIG. 1B is a cross-sectional view showing a state in which the polycrystalline silicon 6 formed as shown in FIG. 1A and then used as a diffusion source is deposited.

FIG. 1C is a state in which the ion implantation 7 is performed after the polycrystalline silicon 6 formed as shown in FIG. 1B is removed using only a photosensitive film, leaving only the region to be ion implanted through dry etching, and removing the remaining polycrystalline silicon 6. It is sectional drawing which shows.

FIG. 1D is a cross-sectional view showing a state in which the N ⁺ and P ⁺ diffusion layers 8 are formed by diffusing for a predetermined temperature and a predetermined time in an ion implanted state as in FIG. 1C.

The various problems which 1e turns after completing the diffusion as the 1d help without the use of the remaining polycrystalline silicon 6, the photoresist that case, a cross-sectional view showing the removed through a dry etching N ⁺ and P ⁺ diffusion layer 8 is over-etched May occur.

2A to 2C are cross-sectional views illustrating a method of forming a thin junction according to the present invention.

FIG. 2A illustrates the diffusion of ions implanted with ions 7 using polycrystalline silicon 6 to form N ⁺ and P ⁺ diffusion layers 8, as shown in FIG. 1D, and then titanium 9 on the remaining polycrystalline silicon 6. It is sectional drawing which showed the state which deposited.

FIG. 2B is a cross-sectional view showing a state in which the titanium silicide 10 is formed by heat-treating the titanium 9 deposited as shown in FIG. 2A and the polycrystalline silicon 6 used as the diffusion source.

FIG. 2C is a cross-sectional view showing a state in which a thin junction is formed by selectively etching the titanium silicide 10 formed in FIG. 2B in a hydrogen fluoride solution. For reference, the titanium silicide has an etching rate of 2000 mW / min or more in a 10: 1 hydrogen fluoride solution.

As described above, the present invention forms a thin junction using polycrystalline silicon as a diffusion source for forming a thin junction, and reacts with titanium without removing the remaining polycrystalline silicon through dry etching to form titanium silicide and then into a hydrogen fluoride solution. It can be etched to form a thin junction.

Claims (1)

Forming a field oxide film, a gate oxide film, a gate electrode, and a spacer oxide film over the silicon substrate, forming a thin junction using polycrystalline silicon as a diffusion source, and using titanium to prevent the polycrystalline silicon from shorting the active region and the gate. A method of forming a thin junction using titanium silicide, comprising: depositing on polycrystalline silicon, and reacting titanium with polycrystalline silicon through heat treatment to form titanium silicide and then etching titanium silicide in a hydrogen fluoride solution.