JPH0547744A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To obtain a cover insulating film having small influence of moisture, etc., to wirings and high reliability in a structure of the film of a semiconductor integrated circuit device and a method for manufacturing the same. CONSTITUTION:A method for manufacturing a silicon nitride film formed on a semiconductor substrate 1 formed with an electrode wiring film 2, comprises the steps of covering the substrate 1 with a first silicon nitride film 4 by a CVD method by using ternary system process gas of silane, nitrogen, ammonia, and then laminating a second silicon nitride film 5 having a thickness twice as thick as that of the film 4 on the substrate by using binary system process gas of silane, nitrogen, containing no ammonia.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure of a cover film of a semiconductor integrated circuit device and a manufacturing method thereof. With the recent trend toward higher integration and multilayer wiring of semiconductor integrated circuits, high reliability is also required for the cover insulating film that protects the surface of the device.

Therefore, it is necessary to reduce the influence of the insulating cover film on the wiring, such as moisture resistance and stress.

[0003]

2. Description of the Related Art FIG. 3 is an explanatory view of a conventional example. In the figure, 17 is a semiconductor substrate, 18 is a wiring film, 19 is a lower insulating film, 20
Is a silicon nitride film.

Silicon dioxide (S
iO ₂ ) film, phosphosilicate glass (PSG) film, or silicon nitride (S
Many i ₃ N ₄ ) films are used, and among these, the Si ₃ N ₄ film is the most excellent in terms of moisture resistance.

Conventionally, when forming a Si ₃ N ₄ film, a ternary gas of silane (SiH ₄ ), ammonia (NH ₃ ), and nitrogen (N ₂ ) is used as a process gas, or SiH _{4 ,} N ₂ binary gas was the mainstream.

However, in the Si ₃ N ₄ film formed by using a ternary gas of SiH ₄ , NH ₃ and N ₂ , the stress due to heat treatment of the substrate is reversed from compression to tension as shown in Table 1 below. easy.

[0007]

[Table 1]

[0008] Therefore, as shown in FIG. ₃ (b), Si 3
After the N ₄ film 20 is formed, the surface of the semiconductor substrate 17 is convex due to the compressive stress. However, if annealing is performed at 450 ° C. for 30 minutes in the N ₂ atmosphere, the surface of the semiconductor substrate 17 is opposite due to the tensile stress. It warps in the concave.

Therefore, the Si ₃ N ₄ film 20 is cracked or the wiring film is broken. In addition, the infrared absorption spectra of the two types of Si ₃ N ₄ films with and without NH ₃ as the process gas were examined to find that the hydrogen content was 2170 cm ⁻¹ when the hydrogen content was high. Si-H, 3340cm
^Since the N-H peak of ^-1 becomes large, as shown in Fig. 4, the S film formed by the ternary process gas using NH ₃ was deposited.
The i ₃ N ₄ film has a drawback that it contains a large amount of hydrogen and causes problems in characteristics.

On the other hand, a Si ₃ N ₄ film formed by using a binary process gas of SiH _{4 and} N ₂ has poor moisture resistance. For example, a product with two-layer wiring has a pressure of 2 atm, a temperature of 121 ° C. and a humidity of 100 Doing% condition moisture resistance test in _{the, SiH 4, NH 3, Si} 3 N 4 film formed by using the ternary gas N ₂ showed good moisture resistance, of SiH _4, N ₂ The Si ₃ N ₄ film formed by using the binary gas had many cracks.

[0011]

[0005] Thus, when used in a semiconductor integrated circuit to the Si ₃ N ₄ film was deposited using a process gas of a configuration of the above two as a cover insulating film, any of Si ₃
Even with the N ₄ film, the reliability was low.

The present invention is provided for the purpose of solving the above problems, improving moisture resistance and stress that affect wiring, and improving reliability of a cover insulating film.

[0013]

FIG. 1 illustrates the principle of the present invention. In the figure, 1 is a semiconductor substrate, 2 is a wiring film,
3 is the lower insulating film, 4 is the first Si ₃ N ₄ film, and 5 is the second Si ₃ N
_{There are 4} membranes.

In order to solve the above problems, Si ₃ N ₄ films formed by using a ternary process gas and a binary process gas containing no ammonia are stacked to form two or more layers. It may be multi-layered.

As a result, the drawbacks of the two kinds of Si ₃ N ₄ films are compensated, and a reliable cover film can be obtained. That is, an object of the present invention is a manufacturing method for forming a Si ₃ N ₄ film on a semiconductor substrate 1 on which a wiring film 2 and the like are formed, which is a ternary process of SiH ₄ , N ₂ and NH _3. CV using gas
The first Si ₃ N ₄ film 4 is coated on the semiconductor substrate 1 by the D method, and subsequently, the above-mentioned first Si ₃ N ₄ film 4 is deposited by the CVD method using a binary process gas of SiH ₄ and N ₂ containing no NH ₃ . The second Si layer having a thickness at least twice that of the first Si ₃ N ₄ film 4 is formed on the first Si ₃ N ₄ film 4.
By laminating the Si ₃ N ₄ film 5 of, or, SiH _4,
By alternately using a ternary process gas of N ₂ and NH _{3 and} a ternary process gas of SiH ₄ and N ₂ , two types of Si ₃ N ₄ films 4 are sequentially formed on the semiconductor substrate 1 by a CVD method. This is achieved by stacking 5 alternately.

[0016]

In the present invention, the first Si ₃ N ₄ film formed by the ternary process gas as the lowermost layer is thinly coated to about 1,000 Å to block (block) water, and the binary A second Si ₃ N ₄ film formed by a system process gas is grown thick.

If the thickness of this film is at least twice the thickness of the former, the change in stress can be reduced.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a schematic cross-sectional view of one embodiment of the present invention, and FIG.

In the figure, 1 is a semiconductor substrate, 2 is a wiring film,
3 is the lower insulating film, 4 is the first Si ₃ N ₄ film, and 5 is the second Si ₃
N ₄ film, 6 chamber, 7 gas shower, 8 quartz window,
9 is a lamp heater, 10 is a gas inlet, 11 is a silane gas container, 12 is a nitrogen gas container, 13 is an ammonia gas container, 14 is an opening / closing valve, 15 is an exhaust port, and 16 is an RF power supply.

An embodiment of the present invention will be described in the order of steps with reference to FIGS. As shown in FIG. 1, the semiconductor substrate 1 is a silicon wafer on which the aluminum (Al) wiring film 2 is already patterned to a thickness of 1 μm, and the PSG film is used as the lower insulating film 3 under the atmospheric pressure CVD layer device. Using
Substrate temperature 410 ℃, SiH ₄ gas 80sccm, Oxygen (0 ₂ ) gas 1slm,
The phosphine (PH ₃ ) gas 900sccm is used as the process gas to coat the thickness of 5,000Å.

Next, using the plasma CVD apparatus shown in FIG. 2, the semiconductor substrate set in the chamber 6 at a substrate temperature of 415 ° C. is heated by the lamp heater 9 through the quartz window 8,
From each process gas container, SiH ₄ 25sccm, NH ₃ 150scc
A ternary process gas of m, N ₂ 300 sccm was introduced into the champer 6 through the gas shower 7 through the gas inlet 10 and RF.
Under the conditions of a frequency of 200 KHz, an output of 30 W, and a chamber 6 internal pressure of 1.0 Torr, a first Si ₃ N ₄ film 4 of 1,000 was formed on the semiconductor substrate 1.
Form to a thickness of Å.

Next, the on-off valve 14 leading to the ammonia gas container was closed, and a binary process gas of SiH ₄ of 80 sccm and N ₂ of 1500 sccm was used, and the first substrate of the semiconductor substrate 1 was processed under the same conditions as described above. A second Si ₃ N ₄ film 5 is formed on the Si ₃ N ₄ film 4 of
Stack to a thickness of 00Å.

As a result, since the two kinds of Si ₃ N ₄ films 4 and 5 were laminated as the cover insulating film, the humidity resistance against the Al wiring film was improved, and the substrate with less stress reversal was obtained.

[0024]

As described above, according to the present invention,
In addition to improving the moisture resistance, it is possible to reduce the degree of stress reversal due to heat treatment, which greatly contributes to improving the reliability of the wiring.

[Brief description of drawings]

FIG. 1 is an explanatory view of the principle of the present invention.

FIG. 2 Plasma CVD apparatus

FIG. 3 is an explanatory diagram of a conventional example.

Fig. 4 Infrared absorption spectrum of Si ₃ N ₄ film

[Explanation of symbols]

1 semiconductor substrate 2 wiring film 3 lower insulating film 4 first Si ₃ N ₄ film 5 second Si ₃ N ₄ film 6 chamber 7 gas shower 8 quartz window 9 lamp heater 10 gas inlet 11 silane gas container 12 nitrogen gas container 13 Ammonia gas container 14 Open / close valve 15 Exhaust port 16 RF power supply

Claims (2)

[Claims] 1. A manufacturing method for forming a silicon nitride film on a semiconductor substrate on which an electrode wiring film is formed, wherein the semiconductor substrate is formed by a CVD method using a ternary process gas of silane, nitrogen and ammonia. The first silicon nitride film is coated on the first silicon nitride film, and then the first silicon nitride film is formed on the first silicon nitride film by a CVD method using a binary process gas containing no ammonia and containing silane and nitrogen. Of the second silicon nitride film having a thickness at least twice as much as the above. 2. A manufacturing method for forming a silicon nitride film on a semiconductor substrate on which an electrode wiring film is formed, which is a ternary process gas of silane, nitrogen, and ammonia and does not contain ammonia. 2. A method of manufacturing a semiconductor device, wherein a silicon nitride film is sequentially deposited on the semiconductor substrate by a CVD method by alternately using the binary system process gas.