JP2642926B2 - Method for producing silicon compound - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for forming an electrode of a semiconductor device, and more particularly to a method for obtaining a stable silicide layer used for an electrode.

[Summary of the Invention]

The present invention provides a method for forming an electrode layer of a semiconductor device such as a VLSI, which comprises forming a high melting point metal layer on a silicon material surface under a high vacuum atmosphere of 10 ^-8 to 10 ^-10 Torr. By forming refractory metal silicide by heat treatment,
This is to obtain a silicon compound having a low resistivity.

[Conventional technology]

There is an increasing need for new materials such as various refractory metals and silicides having lower resistivity than the conventional polysilicon electrodes as gate electrode materials for recent VLSI. This is particularly important in a DRAM process that requires a high degree of integration and a high speed. For example, in a 256 KDRAM, a MoSi ₂ gate structure is partially used for high speed. While 1
As the integration density of MDRAM further increases to 4M and 16MDRAM, the increase in gate electrode and wiring resistance is the biggest factor that determines the operation speed of the device, so reducing the resistance of the gate electrode material has become an important issue. . For example when considering 0.3-0.4μm thickness of the silicide film, is a the WSi ₂ 2-3Ω / □, since at the TiSi ₂ are possible 1 [Omega / □ or less, 1
TiSi ₂ with low resistivity as gate electrode material after MDRAM
(And a polycide structure of TiSi ₂ / polycrystalline Si) are promising.

16th Conference on Solid Sta in Kobe in 1984
At te Devices and Materials, Mitsubishi Electric announced the following: (Extended Abstracts pp47~50) (i) by a thin film lamp annealing of Ti obtained by sputtering on Si where it is silicided in order to obtain an oxygen-existent TiSi ₂ layer of rapid heating by a halogen lamp highly effective It was a target.

(Ii) According to Rutherford backscatter analysis and X-ray analysis, it was found that TiSi ₂ having a stoichiometric ratio could be formed within 30 seconds using lamp annealing at 650 ° C. or higher.

(Iii) Titanium silicide formed by self-alignment using two-step lamp annealing is MOS
Suitable for source / drain and gate of transistor.

[Problems to be solved by the invention]

Since Ti is extremely active, when Ti is deposited on a doped polycrystalline Si film and silicided by heat treatment, it reacts with oxygen contained in the heat treatment atmosphere to form TiO _x, resulting in good TiSi There was a problem that _two layers were not formed.

[Means for solving the problem]

According to the present invention, in order to suppress the reaction between Ti and oxygen as much as possible, the metal layer is deposited in a chamber of an extremely high vacuum (up to 10 ^-8 Torr) deposition apparatus, and then the vacuum is broken in the chamber. Instead, by performing short-time annealing such as lamp annealing, it is possible to suppress the invasion of oxygen into the TiSi ₂ layer and to form a good silicide layer.

[Action]

According to the method of the present invention, since a very active metal surface is annealed in a very good vacuum without being exposed to the air as in the conventional method, a chemically stable semiconductor compound can be obtained. Can be. The present invention relates to formation of silicide such as TiSi _{2 which} is effective as a gate electrode material. After Ti is deposited on silicon, it is silicided by heat treatment such as lamp annealing, but Ti is chemically active and reacts with a small amount of oxygen in the heat treatment atmosphere to form a silicide on the surface.
There is a problem that TiO is formed to suppress the silicidation reaction, thereby making it difficult to reduce the resistance. The deposition of metals such as Ti is performed in an atmosphere with a very good vacuum.However, using this same atmosphere, after deposition, annealing is performed without breaking vacuum in the same chamber or in the same device to oxidize the surface. And a stable silicide layer can be formed.

〔Example〕

In order to form a stable silicide layer, an atmosphere having a good degree of vacuum is required. Therefore, when depositing a metal such as Ti, a high vacuum of ~ 10 ^-8 is used, but using the atmosphere, in the same chamber where Ti was deposited or in the same apparatus. Annealing is performed to form a stable silicide layer. FIG. 1A shows an example of the apparatus. This is one in which an annealing device such as a lamp annealing device is attached to a vapor deposition device and integrated. The heating device installed in the conventional vapor deposition device is used only for preheating of the Si wafer before vapor deposition and baking of the device. Is the present invention.

RF sputtering is performed on the wafer introduced from the wafer introduction chamber 5 in the cleaning chamber 6 to remove a natural oxide film on the wafer surface to expose a clean surface.
Then, in the vapor deposition chamber 7, 50
0 ° evaporation to form a structure as shown in FIG. 1B. Next, annealing is performed by the second heater 10 without breaking the vacuum of the sputter deposition chamber 7 to form a TiSi ₂ layer.
Thereafter, the wafer is moved to collect the wafer from the wafer introduction chamber 5.

〔The invention's effect〕

Fig. 2 shows a normal pressure type (atmospheric pressure) IR
Ti + N (418 eV), Ti (39 e) in the depth direction after the sample was annealed at 800 ° C. for 30 seconds using an annealing furnace.
3eV), Auger Intensity of Si (92eV), O (518eV). As can be seen from this result, oxygen has penetrated from the surface, and it can be understood that the progress of the formation of TiO _x suppresses the silicide reaction. FIG. 3 shows the AES result of a sample obtained by annealing a similar sample at 800 ° C. for 30 seconds by low-pressure (in vacuum) IR annealing. From this result, it can be seen that TiN is formed on the surface and oxygen is present on the extreme surface, but only a stable TiSi ₂ layer is formed without oxygen inside.

In addition, Ps is used for normal pressure (atmospheric pressure) IR annealing.
Ps = 6.3Ω / □, Ps = in reduced pressure (in vacuum) IR annealing
The resistance was 1.8 Ω / □, and the resistance obtained by forming the silicide layer by low-pressure IR annealing was found to be much lower.

On the other hand, the manufacturing apparatus used in the manufacturing method of the present invention includes:
Since the conventional vapor deposition apparatus with a heater for preheating or the like can be used as it is, the present invention has another effect that it is not necessary to modify the apparatus.

[Brief description of the drawings]

FIG. 1A shows the manufacturing method of the present invention. FIG. 1B shows an electrode structure used in the manufacturing method of the present invention. FIG. 2 shows the results of Auger analysis of a sample annealed by a normal-pressure IR furnace. FIG. 3 shows the results of Auger analysis of a sample annealed by a reduced pressure IR furnace. 1 ...... Si substrate, 2 ...... SiO ₂ layer 3 ...... doped polycrystalline Si layer, 4 ...... Ti layer 5 ...... wafer introducing chamber, 6 ...... cleaning chamber 7 ...... sputter deposition chamber, 8 ...... Ti target 9 ... 1st heater, 10 ... 2nd heater

Continuation of the front page (72) Inventor Dr. Yamamoto 6-7-35 Kita-Shinagawa, Shinagawa-ku, Tokyo Inside Sony Corporation (56) References JP-A-60-226174 (JP, A) JP-A-59-121834 (JP, A) JP-A-58-121 (JP, A) JP-A-60-182133 (JP, A) JP-A-51-130169 (JP, A)

Claims (1)

(57) [Claims] 1. A forming a metal layer on a silicon material, the method for producing a silicon compound to a heat treatment, a step of removing a natural oxide film of the silicon material surface, a high vacuum atmosphere of 10 ^-8 to 10 ^-10 Torr Forming a refractory metal layer on the surface of the silicon material and then forming a refractory metal silicide by heat treatment.