JPH0237723A - Stress migration prevention method - Google Patents

Abstract

PURPOSE:To prevent stress migration from being generated after producing LSI by performing high-frequency heating treatment entirely and relieving stress migration generated on a metallizing layer. CONSTITUTION:When a material is accumulated and grown on a semiconductor substrate 1, it is eliminated, impurity ions are implanted and diffused, heating and metallizing is performed to allow an integrated circuit to be formed and then an Al wiring 3 at the final state is completed, a high-frequency heating treatment is performed entirely to relieve residual stress generated at the metallizing layer. Thus, only the Al wiring 3 is heated by high-frequency heating and no SiO2 which is an insulation film 2 is heated. Also, since the periphery is fixed by SiO2 although the Al wiring 3 tries to expand, no expansion is possible, thus resulting in plastic deformation. Thus, continuous heating achieves recovery, recrystallization, and relieves residual tensile stress, thus preventing stress migration from occurring.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for preventing stress migration from occurring in the wiring of an LSI, particularly a VLSI.

(Prior Art) Conventionally, when forming various semiconductor devices as desired in a large-scale integrated circuit (LSI), Δl wiring is used for mutual wiring between the various semiconductor regions and connection wiring to external devices. It is used in most cases. In recent years, as the density and size of I, S+ and very large scale integrated circuits (VLSI) have increased, multilayer wiring structures have been adopted, and the cross-sectional area of the wiring itself has become smaller, resulting in electromigration and stress migration. A problem has arisen in which an undesirable phenomenon called .

(Problems to be Solved by the Invention) In such AI wiring, a 5iOy film is deposited as an interlayer insulating film after aluminum (AQ) wiring, but the temperature rise during deposition reaches about 400°C.

Further, the deposition temperature of AI is approximately 200'C. Therefore,
Difference in linear thermal expansion coefficient between Δl and S+O (A I, 23
．． 5: 5ift.

0.6(IF'°C-1)), tensile stress remains in Δl after cooling. Therefore, as the AI wiring is used for a long period of time, stress concentration occurs in a portion of the AI wiring, which causes wire breakage. In particular, this tendency becomes more pronounced when the Af wiring becomes thin, such as in a semiconductor device of medium submicron size.

The present invention has been made in view of the above-mentioned points, and an object of the present invention is to provide a method for preventing stress migration that may occur after LS1 manufacturing.

(Means for Solving the Problems) The present invention forms an integrated circuit by subjecting a semiconductor substrate to processes such as material deposition or growth, material removal, impurity ion implantation and diffusion, heating, metallization, etc. This is characterized in that when the final stage of AI wiring is completed, the entire structure is subjected to high-frequency heat treatment to relieve residual stress generated in the metallized layer.

Furthermore, it goes without saying that the present invention can be applied not only to AI wiring but also to metal wiring such as Au wiring.

(Function) By performing high-frequency heating, Af is heated because it is a conductor, but Sin is hardly heated because it is an insulator, so only the A/wiring expands and the surrounding area is fixed. As a result, plastic deformation occurs, which is recovered and recrystallized by further heating, so that residual tensile stress in the AI wiring can be alleviated, and subsequent stress migration can also be prevented.

(Example) Figure 2 shows an insulator (Sin, film) 2 provided on an LSI substrate (for example, a silicon substrate) 1 at a temperature of about 400°C.
4 and 4, and a generally configured LSI device with At wiring 3 provided at a temperature of 200° C. is shown in cross section. As is clear from this configuration, the At wiring 3 is connected to the S+Ot films 2 and 4.
It is firmly fixed by. This state is Sin,
The heat treatment temperature of films 2 and 4 is 400°C, and the At wiring 3
Since the heat treatment temperature is 200°C, the At wires 3 undergo thermal expansion according to their respective linear thermal expansion coefficients during heating, and tensile stress remains in the At wire 3 due to subsequent cooling. As a result of long-term use, stress concentration occurs in a portion of the wiring, resulting in a constriction in the AI wiring, as shown in FIG. Stress concentration further occurs in this constricted portion 5, leading to wire breakage.

Therefore, as shown in FIG. 1, when an LSI or yt, s+ device is completed and the entire device is heated to a high temperature using a high frequency heating device, only the Δl wiring is heated, and the insulating film SiO2 and the semiconductor layer are not heated. Therefore, the Δl wiring tries to expand, but since it is surrounded by Sin,
It cannot expand and undergoes plastic deformation. Therefore, by continuing to heat it, it recovers and recrystallizes, and as a result, the residual tensile stress can be alleviated.

(Experimental example) LSIs subjected to high frequency heating according to the present invention and 1. LSI not subjected to high frequency heating. A comparison of the number of stress migration occurrences with SI was as follows.

(Effects of the Invention) As described above, according to the present invention, A
Only t is heated, and the insulating film Sio is not heated. Therefore, although the Tol wiring tries to expand, the surrounding S
Since it is fixed in, it cannot expand and undergoes plastic deformation. Therefore, by continuing to heat it, it recovers, recrystallizes, and relieves the residual tensile stress.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing a part of an integrated circuit manufactured by the method for preventing stress migration according to the present invention. FIG. 2 is a cross-sectional view showing AI wiring and interlayer insulation layers provided on the integrated circuit substrate. , FIG. 3 is a sectional view showing the conventional example. Semiconductor substrate (silicon substrate) Insulating layer (S102 film) A! Wiring insulating layer (silicon substrate) narrow part

Claims (1)

[Claims] 1. After forming an integrated circuit on a semiconductor substrate by performing processes such as material deposition or growth, material removal, ion implantation and diffusion of impurities, heating, and metallization, the whole is subjected to high-frequency heat treatment to metallize it. A method for preventing stress migration, characterized in that stress migration occurring in a layer is alleviated.