JPH0157507B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Technical Field of the Invention The present invention relates to the origin of MIS type semiconductor devices.

(b) Background of the technology MIS type semiconductor devices such as MIS type ICs and MIS type LSIs used in electronic devices are required to operate at high speed. Metal silicide electrodes with high melting points, such as molybdenum silicide (MoSi ₂ ) and tungsten silicide (WSi ₂ ), which have low electrical resistance, are increasingly being used in place of silicon electrodes.

(c) Prior art and problems By the way, when such a metal silicide film is used as a gate electrode of an MIS type semiconductor device, after forming the gate electrode, impurities for forming source and drain regions are added to silicon using the gate electrode as a mask. (Si) After ion implantation into the substrate, the process of heat treating the substrate and gate electrode. Source area. After forming the drain region, a phosphosilicate glass (PSG) film is formed on the substrate and then heat treated. In such a heat treatment process, a phenomenon occurs in which metals such as molybdenum ( _{Mo) and tungsten (W) in the metal silicide film diffuse into the gate SiO 2 film} under the gate electrode of the metal silicide. This causes problems such as the breakdown voltage deteriorates and the characteristics of the formed MIS type semiconductor device deteriorate.

(d) Purpose of the Invention The present invention eliminates the above-mentioned problems, and when a gate electrode of an MIS type semiconductor device is formed using a metal silicide film, the metal silicide film is The purpose of this invention is to provide a semiconductor device in which metal atoms in a silicide film do not diffuse into a gate SiO ₂ film.

(e) Structure of the Invention In order to achieve the above object, the semiconductor device of the present invention is a MIS type semiconductor device comprising a source region, a drain region, a gate insulating film, and a gate electrode, in which the gate electrode is made of a nitrogen compound of metal silicide. It is characterized by: Furthermore, the gate electrode is formed by sequentially stacking a metal silicide nitrogen compound film and a metal silicide film.

(f) Embodiment of the Invention An embodiment of the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a sectional view showing the structure of a semiconductor device of the present invention, and FIG. 2 is a schematic diagram of an apparatus for forming the device.

As shown in the figure, the semiconductor device of the present invention has a P-type Si substrate 2 defined by an SiO ₂ film 1 for element isolation, and an N-type impurity atom (P) or arsenic (As).
A source region 3 and a drain region 4 are formed by ion implantation of atoms. and the Si substrate 4
A gate electrode 6 made of a metal silicide such as MoSi ₂ and a nitrogen compound film patterned into a predetermined shape is formed thereon via a gate SiO ₂ film 5 . The metal silicide may be WSi ₂ or tantalum silicide (TaSi ₂ ) in addition to MoSi ₂ . If a gate electrode is formed from a compound film of metal silicide and nitrogen in this way, the metal elements such as Mo. As a result, it is possible to suppress the migration and therefore to prevent diffusion into the gate oxide film, thereby making it possible to form a high breakdown voltage MIS type semiconductor device that does not cause deterioration of the breakdown voltage of the gate oxide film.

As another example, in order to reduce the electrical resistance of the gate electrode, the lower part of the gate electrode is formed with a nitrogen compound film of the metal silicide film, so that the metal atoms in the metal silicide film are absorbed into the gate oxide film. The gate electrode may have a two-layer structure in which the upper part of the gate electrode is formed of a metal silicide film.

To form such a semiconductor device, as shown in FIG.
The SiO ₂ film 2 is formed by thermally oxidizing the substrate. Next, after a gate SiO ₂ film is formed by thermal oxidation of the substrate, the substrate 2 is placed on a substrate mounting stand 12 in a container 11 of a sputtering apparatus shown in FIG. Next, the inside of the container 11 is evacuated to about 10 ^-2 Torr through the exhaust hole 13, and then 5
Introduce argon (Ar) gas to which ~6% by volume nitrogen gas is added. Thereafter, the substrate installation table 12 is grounded, a negative high voltage is applied to the Mo target 15 and the Si target 16 to ionize the Ar gas, and the targets are sputtered using the Ar gas as a sputtering gas to form MoSi ₂ on the substrate. Form a nitrogen compound film. Next, a photoresist film is applied onto the substrate, and then the resist film is formed into a predetermined pattern by photolithography and plasma etching. Next, using the patterned resist film as a mask, the MoSi ₂ nitrogen compound film is formed into a predetermined pattern by plasma etching using, for example, carbon tetrachloride (Ccl ₄ ) gas as an etching gas. Use as gate electrode.
Thereafter, using the thus patterned gate electrode as a mask, As or P atom ions are implanted onto the substrate to form a source region 3 and a drain region 4.

(g) Effects of the Invention As described above, according to the semiconductor device of the present invention, the metal atoms of the metal silicide film forming the gate electrode are prevented from diffusing into the gate oxide film, and a gate oxide film with a high breakdown voltage can be formed. This brings about the advantage that a semiconductor device with good characteristics can be obtained.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing the structure of a semiconductor device of the present invention, and FIG. 2 is a schematic diagram of an apparatus used to form the semiconductor device of the present invention. In the figure, 1 is SiO ₂ film for isolation between elements, 2 is Si
Substrate, 3 is a source region, 4 is a drain region, 5 is a SiO ₂ film for gate, 6 is a gate electrode made of a compound of MoSi ₂ and nitrogen, 11 is a container, 12 is a substrate installation stand, 13 is an exhaust port, 14 is the gas introduction hole, 15 is
Mo target, 16 indicates Si target.

Claims (1)

[Claims] 1. Source area. Drain area. 1. A MIS type semiconductor device comprising a gate insulating film and a gate electrode, wherein the gate electrode is made of a nitrogen compound of metal silicide. 2. The semiconductor device according to claim 1, wherein the gate electrode is formed by sequentially stacking a metal silicide nitrogen compound film and a metal silicide film.