JPH04158552A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To improve humidity resistance and an effect of contamination resistance and to improve the reliability of a miniaturized semiconductor device by a method wherein a first silicon nitride film is formed, a spacer is formed on the side wall of a metal wiring by anisotropic etch back and then a second silicon nitride film is formed on the occasion when a protective insulation film is formed. CONSTITUTION:After metal wirings 14 and 15 are formed, a first silicon nitride film 16 is made to grow by bringing SiH4 and NH3 into a plasma reaction with N2, used as a carrier. Next, anisotropic etch back is applied by CF4, C2, F6 and 02, so that a spacer constituted of the silicon nitride film 16 is formed in the side wall parts of the metal wirings, and then a sintering process is executed. Next, a second silicon nitride film 17 is deposited by a plasma reaction and then subjected to sective dry etching, and thereby a bonding pad 19 for extraction of an external electrode is opened.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method for manufacturing a semiconductor device, and particularly to the formation of a protective insulating film.

[Conventional technology]

Conventionally, the protective insulating film on the final metal wiring of semiconductor devices used in LSI etc. is a plasma silicon nitride film grown in a vapor phase at low temperature to prevent physical damage, contamination, and moisture intrusion. requires 8000A or more.

In the conventional method of manufacturing a semiconductor device, for example, as shown in FIG. SiH4 and N are applied as a protective film on the metal wiring of the alloy film 14 at a low temperature of about 300 to 400°C.
A silicon nitride film 17 with a thickness of about 1.0 μm is grown in a vapor phase by a plasma reaction introducing H8 or N2, and then, using a patterned photoresist as a mask, the silicon nitride film 17 is grown with CF4, C2FB, NFS, or 0.
Selective dry etching is performed using a mixed gas such as No. 2, etc. to open a bonding pad 19 for taking out an external electrode, and if necessary, a polyimide resin or the like is further laminated to relieve stress during molding.

[Problem to be solved by the invention]

However, with conventional technology, as semiconductor devices such as LSIs are miniaturized to the submicron level, the patterning of metal wiring becomes tri-etching, the cross-sectional shape becomes steeper, and the aspect ratio (steps/spaces) increases. Due to the large size, cusping of the silicon nitride film 17 causes
A slit 20 is formed in the space of the metal wiring, which becomes a contamination trap. In addition, the silicon nitride film 17 on the sidewalls, bottom surface, and four corners of the metal wiring is extremely thin compared to the top of the metal wiring, and the silicon nitride film 17 is formed in this area. The intrusion of moisture and contamination has caused problems in the long-term reliability of semiconductor devices, including fluctuations in transistor characteristics and field inversion breakdown voltage, and corrosion of l-wirings. Even if the thickness of the silicon nitride film is simply increased, voids are formed in the flat portion, and the thickness of the silicon nitride film in the four parts hardly changes, and reliability is not improved.

However, the present invention solves these problems, and aims to improve the moisture resistance and anti-contamination effects of the protective insulating film, thereby improving the reliability and stable supply of fine semiconductor devices.

[Means to solve the problem]

The method for manufacturing a semiconductor device of the present invention includes at least the step of forming a first silicon nitride film by plasma reaction in forming a protective insulating film on the final metal wiring of the semiconductor device, and forming the silicon nitride film anisotropically. The method is characterized by comprising a step of etching back to form a spacer on the side wall of the metal wiring, a step of forming a second silicon nitride film by plasma reaction, and a step of opening a bonding pad for taking out an external electrode.

〔Example〕

FIG. 1 is a schematic cross-sectional view for explaining one embodiment of the method for manufacturing a semiconductor device of the present invention.
The case is shown in which it is applied to an insulating protective film of Os-LSI. Semiconductor elements such as P and NMO3) transistors and high resistance are formed on the silicon substrate 11, contact holes are formed in the impurity layer 18, etc. through the field insulating film 12 and the interlayer insulating film 13, and Cu is deposited approximately. 0. The Ag alloy film 14 containing 5% is about 1. After sputtering a TiN film 15 as a cap metal in 600 layers, the minimum spacing is approximately 0.8 μm using a photolithography process.
A pattern was formed, and the laminated film was dry etched using a Freon gas and a CF2 gas to form metal wirings (14, 15) having substantially vertical side surfaces. Next, in a vapor phase growth apparatus equipped with parallel plate electrodes with a load lock, the first silicon nitride 1M116 was grown at about 360° C. using N2 as a carrier and a plasma reaction of SiH4 and NH3 at a pressure of 6 torr. It was grown to 5 μm. At this time, the heating time until the start of film growth was 30 seconds, the growth rate was 0.7 μm/min, and the total treatment time was within 4 minutes to suppress the growth of Al hillocks. Next CF4, C2, FB and 02
After performing anisotropic etch-back to form a spacer made of silicon nitride film 16 on the side wall of the metal wiring, 450'C13%H2/A was applied to stabilize the electrical characteristics of the transistor etc.
A sintering process was performed for 30 minutes in a r atmosphere (Fig. 1-a).

At this time, the top surface of the A1 alloy film 14 is covered with a TiN film 15, and the side surface is covered with a spacer of a silicon nitride film 16, so there is no growth of lateral AI hillocks, which is a problem with fine metal interconnects, and leakage between interconnects occurs. do not. Next, the second silicon nitride film 17 subjected to the plasma reaction in the same manner as above is coated with a film of about 1.0 μm.
Then, using the patterned photoresist as a mask, the second silicon nitride film 17 was selectively dry etched to form a bonding pad 19 for taking out an external electrode (FIG. 1-b).

In the semiconductor device constructed in this way, even if there is cusping in the second silicon nitride film 17, sidewall spacers made of the first silicon nitride film 16 are formed at the four corners, and the film thickness is effectively reduced. The moisture resistance and contamination shielding effect have been greatly improved, and the number of defects in conventional device reliability tests has been drastically reduced. In addition, the shape of slits and voids in the silicon nitride film has been improved, and the effect of the sidewall spacer is to prevent deterioration of the migration characteristics of metal wiring whose thickness tends to be equal to or even larger than the minimum width and physical stress in the lateral direction. A relaxing effect was also observed.

As another example, we applied it to the manufacture of LSI memory with redundant circuits to increase the yield by melting polysilicon etc. with a laser. After applying metal wiring made of 19 alloy film, on this metal wiring, Si(OC2H5)4 and 02 are reacted at 400°C using a vapor phase growth apparatus to form a silicon nitride film with less cusping, or phosphorus glass added with P (CH3)3. To reduce stress damage to the plasma silicon nitride film in the subsequent process, the film is heated to about 0. After growing to a thickness of 3 μm, sintering was performed for 30 minutes in a 3% H2/Ar atmosphere at 450°C, the initial electrical characteristics were measured, and a laser repair process was performed. SiH4 and N
The first silicon nitride film produced by plasma reaction of H3 was heated to 0.
After growing to a thickness of 4 μm and etching back the anisotropy, a second silicon nitride film subjected to a plasma reaction in the same manner as described above was deposited to a thickness of about 0.8 μm. Furthermore, using the patterned photoresist as a mask, the second silicon nitride film and silicon oxide film or PSG film were dry-etched to form bonding pads for taking out external electrodes. Incidentally, ultraviolet irradiation treatment is performed between each step to erase charge damage generated from plasma equipment, etc. for vapor phase growth and etching treatment during the process. In the semiconductor device constructed as described above, the same improvement effect as in the above embodiment was observed, and the reliability was improved.

Furthermore, the present invention is applicable not only to MOS-LSI but also to bipolar, D
It can also be applied to MO3, LSIs, etc. that combine MO3, and semiconductor devices with multilayer wiring. For metal wiring, A1
1-Not limited to Cu, but also Si and Ti.

Those containing Pt5Mg, etc., those with a laminated structure on top or bottom of high melting point metals such as Ti, WSP t, Mo, their nitrides, silicides, or their alloys for hillocks and contact barriers, or these It can also be applied to products laminated with polyimide resin or the like to alleviate mold stress later.

〔Effect of the invention〕

As described above, according to the present invention, the protective insulating film has a laminated structure of a sidewall spacer of a plasma silicon nitride film and a silicon nitride film, and the protective insulating film itself is formed in a semiconductor device such as a miniaturized MOS-LSI. Improved rotation problems,
It improves moisture resistance and contamination resistance, prevents the occurrence of hillocks in metal wiring, improves quality related to long-term reliability including electrical characteristics, and contributes to the stable supply of more integrated and multifunctional semiconductor devices. It is possible.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic cross-sectional view showing an embodiment of a method for manufacturing a semiconductor device according to the present invention. FIG. 2 is a schematic cross-sectional view of a conventional method of manufacturing a semiconductor device. 11... Silicon substrate 12... Field oxide film 13... Interlayer insulating film 14... Al1 alloy film 15... TiN film 16... First silicon nitride film 17... Second silicon Nitride film 18... Impurity layer 19... Bonding pad 20 drops... Slit or more Applicant: Seiko Epson Corporation

Claims (1)

[Claims] In forming a protective insulating film on the final metal wiring of a semiconductor device, at least a step of forming a first silicon nitride film by plasma reaction, and anisotropic etching back of the silicon nitride film to form a spacer on the side wall of the metal wiring are performed. 1. A method of manufacturing a semiconductor device, comprising the steps of: forming a second silicon nitride film by plasma reaction; and forming a bonding pad for taking out an external electrode.