JPH02260640A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To prevent the deterioration of the characteristics of a MOSFET due to hot electrons, to superpose a second protective film and to prevent an intrusion of H and water from the outside by a method wherein openings are formed in a first layer protective film, P-SiN film, and the H in the MOSFET is diffused to the outside through the openings. CONSTITUTION:A gate electrode 3 is provided on a gate oxide film (a gate insulating film) 2 of a P-type semiconductor Si substrate 1 and N-type source and drain regions 4 and 5 are formed. The whole surface including the electrode 3 is covered with an interlayer insulating film 6 and openings are formed to provide metallic wirings 9. Then, the whole surface is covered with a P-SiN film (a first protective film) 10, openings 11 are formed, the substrate is exposed to a H2-free non-oxidizing atmosphere of 200 to 450 deg.C for 1 to 20 hours and H (hydrogen) is diffused to the outside through the openings 11. Subsequently, a second protective film, a P-SiN film 12 is deposited and the film 12 on pad parts only is removed. According to this constitution, the deterioration of the characteristics of a MOSFET due to hot electrons which are caused by the H can be inhibited up to a degree identical with the case where a PSG film is used.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method of manufacturing a semiconductor device. In particular, the present invention relates to a method of manufacturing a protective film for semiconductor integrated circuits.

[Summary of the invention]

The present invention uses a nitride film (P-3iN) formed as a protective film by chemical vapor deposition using plasma in the manufacture of MO3 type semiconductor integrated circuits made of a metal-oxide-semiconductor.
) is used as the first layer protective film, hydrogen in the integrated circuit is diffused outward into the atmosphere by means such as heating, and then a nitride film ( A metal film such as aluminum (P-3iN) or aluminum formed by sputtering is used as the second layer protective film.

[Conventional technology]

MO3 type semiconductor device (integrated circuit) using conventional protective film
The manufacturing method will be explained using FIG.

A gate oxide film 52 is provided on the surface of a P-type semiconductor substrate 51 (FIG. 2(a)). A gate electrode 53 usually made of polyrecon is provided on a part of the gate oxide film 52 (see FIG. 2).
b)). Using the gate electrode 53 as a mask, an N-type source region 54 and a drain region 55 are formed by ion implantation or the like (FIG. 2(C)). An interlayer insulating film 56 is formed to cover the gate electrode 53 and the gate oxide film 52 (FIG. 2(d)).
). Gate oxide film 52 and interlayer insulating film 56 are removed from part of source region 54 and drain region 55, and interlayer insulating film 56 is removed from part of gate electrode 53.
After removing PJ56 and forming a contact hole,
Desired regions are connected using metal wiring 59 made of aluminum or the like (FIG. 2(e)). After depositing the protective film 60 made of P-3iN over the entire surface, the protective film 60 is removed only from the external lead portion (pad portion) (FIG. 2(r)).

[Problem to be solved by the invention]

As mentioned above, the conventional technology uses P-3iN as a protective film for semiconductor integrated circuits. This is because P-3iN is much less permeable to moisture than phosphorus glass such as PSG.

However, it has been revealed that the P-3iN protective film accelerates the deterioration of MOS transistors due to hot electrons accompanying the miniaturization of semiconductors. This deterioration occurs when hydrogen generated during the manufacturing process of the semiconductor integrated circuit is trapped inside the MOS transistor by P-3iN. This is because P-3iN is extremely difficult to pass not only moisture but also hydrogen.

[Means to solve the problem]

The present invention eliminates the above-mentioned drawbacks and provides a protective film for semiconductor integrated circuits that can cope with the miniaturization of semiconductors.
After forming the iN film as the first protective film, heat treatment is performed in a non-oxidizing atmosphere that does not contain hydrogen to remove the hydrogen trapped inside the MO5I transistor.
A metal film such as P-3iN or aluminum is placed as a second protective film to diffuse hydrogen and water to the outside of the semiconductor integrated circuit through the window provided in the second protective film. I made it.

[Effect]

MOS) The hydrogen trapped inside the transistor is converted to P-
By diffusing to the outside of the semiconductor integrated circuit through the window provided in the 3iN film, it is possible to suppress the deterioration of the MO3I-transistor caused by hydrogen due to hot electrons to the same extent as when the P-3iN film is not used. can.

Furthermore, the second protective film can prevent hydrogen and water from entering from the outside.

〔Example〕

FIG. 1 +al~(hl is a cross-sectional view in the order of steps of the method of manufacturing a semiconductor device according to the present invention. A gate oxide film 2 is provided on the surface of a P-type semiconductor substrate 1 (FIG. 1(a)). Usually polysilicon A gate electrode 3 made of the following is provided on a part of the gate oxide film 2 (FIG. 1(b)). Using the gate electrode 3 as a mask, an N-type source region 4 and a drain region 5 are formed by ion implantation or the like ( Figure 1(C)).Gate electrode 3
and an interlayer insulating film 6 covering the gate oxide film 2 (first
Figure (d)). Gate oxide film 2 and interlayer insulating film 6 are removed from part of source region 4 and drain region 5, and interlayer insulating film 6 is removed from part of gate electrode 3.
After removing and forming contact holes, desired regions are connected using metal wiring 9 such as aluminum (FIG. 1(e)). A first protective film 10 made of P-3iN is deposited on the entire surface (FIG. 1(f)). After removing a portion of the first protective film 10 to form the window 11, the entire device is exposed to a non-oxidizing hydrogen-free atmosphere of about 200 to 450° C. for 1 to 20 hours, and the semiconductor device is directly exposed. Contained hydrogen (l
() to the outside from the window 11 (Figure 1 (g))
. Further, after depositing the second protective film 12 made of P-3iN, the second protective film 12 is removed only at the external extension portion (band portion) (FIG. 1(h)).

In the above embodiment, P-3iNli was used as the second protective film, but the second protective film may also be a metal film such as aluminum.

Furthermore, although an N-channel type MOS transistor has been described as a semiconductor element, the present invention is a P-channel type MOS transistor.
) It can be used in exactly the same way for transistors.

〔Effect of the invention〕

As described above, according to the present invention, by opening a window in the 1N PSiN film and diffusing the hydrogen contained in the MOS transistor to the outside, deterioration of characteristics due to hot electrons can be suppressed. This has an effect that can be suppressed to the same extent as when glass is used as a protective film.

[Brief explanation of drawings]

FIG. 1 (al to thl are step-by-step cross-sectional views of a method for manufacturing a semiconductor device according to an embodiment of the present invention, and FIG. 2 (al to (fl) are step-by-step cross-sectional views of a conventional method for manufacturing a semiconductor device. 1.51・ 2.52 3, 53・ 4.54・ 5.55・ 6 56・ 9I 59・ 60・ ・ P-type semiconductor substrate Gate oxide film Gate electrode Source region Drain region Interlayer insulating film Metal wiring protective film Applicant: Seiko Electronic Industries Co., Ltd. Agent Patent Attorney: Keisuke Hayashi (b) (C) Story (d) (/l) Semiconductor in this book/) HaI: Hodono 119 cross-sectional view Figure 1 (d) Figure 2 of conventional + conductor device

Claims (4)

[Claims] (1) A step of providing a gate oxide film on the surface of a semiconductor substrate of one conductivity type, a step of providing a gate electrode on a part of the gate oxide film, and a step of providing a source region and a drain region of opposite conductivity type on both sides of the gate electrode. a step of providing an interlayer insulating film covering the gate electrode and the gate oxide film; and a step of forming a contact hole by removing a part of the gate oxide film and the interlayer insulating film, and then inserting the metal wiring into the contact hole. and a desired region, a step of providing a first protective film covering the metal wiring and the interlayer insulating film, and a step of removing a portion of the first protective film to form a window. A method for manufacturing a semiconductor device comprising the steps of: providing a second protective film covering the first protective film and the window; diffusing hydrogen in the transistor outward through the window; and providing a second protective film covering the first protective film and the window. (2) The semiconductor device according to claim (1), wherein the first protective film and the second protective film are nitride films formed by chemical vapor deposition using plasma. manufacturing method. (3) The method for manufacturing a semiconductor device according to claim (1), wherein the second protective film is a thin film of metal such as aluminum. (4) The method of manufacturing a semiconductor device according to claim (1), wherein the step of outwardly diffusing hydrogen in the transistor through the window involves heating at about 200 to 450°C.