1. Field of the Invention
The present invention relates to a method of forming a film such as an insulating film, a protective film or the like employed in a semiconductor element or the like, and particularly to a method capable of forming a film without giving damage to a semiconductor element or the like in a forming process.
2. Description of the Related Art
In the manufacture of a semiconductor integrated circuit, for example, an insulating film is made up of SiO2 or the like, and a protective film is made up of a nitride film such as Si3N4. These films are generally formed by a Chemical Vapor Deposition (CVD) method but has heretofore been formed by a plasma CVD method (see Patent Documents 1 and 2) or thermal CVD methods such as an LP (Low Pressure) CVD method or the like.
For example, the nitride film made up of Si3N4 is grown by an LPCVD method done at a high reaction temperature ranging from 800° C. to 900° C. using dichlorosilane and ammonia gases as material gases.
There was also known an ECR-CVD method (Electron Cycrotron Resonance-Chemical Vapor Deposition method) (see Patent Document 3).
However, a drawback arose in that when the protective film or the insulating film was deposited by the thermal CVD method, plasma CVD method or ECR-CVD method referred to above, damage was given to the semiconductor integrated circuit.
Described specifically, the spread of a diffused layer has occurred due to a high reaction temperature in the case of the thermal CVD method. Further, a semiconductor element has suffered damage due to charged particles in plasma in the case of the plasma CVD method. Furthermore, about 400° C. is considered to be needed as the temperature of an electrochemical reaction even in the case of the ECR-CVD method although it is less than expected by the thermal CVD method. Thus, the spread of a diffused layer occurred.
On the other hand, when the semiconductor integrated circuit is micro-fabricated, each of MOSFETs (Metal Oxide Semiconductor Field Effect Transistors) formed in such a semiconductor integrated circuit, for example, becomes constructionally short in gate length, and the depth of a diffused layer such as a channel becomes shallow and its width becomes also narrow. Thus, a defective condition such as the spread of the diffused layer due to the above-described heat is now becoming a problem to be solved, which is important to the micro-fabricated semiconductor integrated circuit.
Patent Documents 1, 2 and 3
Japanese Unexamined Patent Publication No. Hei 6(1994)-283520: refer particularly to paragraph 0077.
Japanese Unexamined Patent Publication No. Hei 11(1999)-214670
Japanese Unexamined Patent Publication No. 2001-15698