JPS61193469A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To easily obtain an interlayer insulating film free from such defects as 'constriction' and the breakage of Al, by forming interlayer insulating films by using both a process of forming an interlayer insulating film without the impression of a substrate bias voltage, and a process of forming another interlayer insulating film with the impression of the substrate bias voltage. CONSTITUTION:A silicon oxide film 31 is formed on the pattern of an Al wiring 2 formed on a semiconductor substrate 1, by means of a sputtering method without the impression of a substrate bias voltage. The thickness of this silicon oxide film 31 is made so thin as to be enough to protect the Al wiring 2 which is the ground. Next, a silicon oxide film 32 is formed by the sputtering method with relatively strong impression of the substrate bias voltage. The stress of the silicon oxide film 32 is high, through this film is excellent in coverage. However, the silicon oxide film 31 is already formed, and therefore the stress caused by the silicon oxide film 32 has no direct effect on the Al wiring 2. Accordingly, there occurs no defect such as the breakage of Al.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method of manufacturing a semiconductor device, and particularly to a method of forming an interlayer insulating film using a sputtering method in forming multilayer wiring.

[Prior Art] As a conventional method for forming an insulating film by sputtering, there is a method as shown in FIGS. 3 and 4.

FIG. 3 is a diagram showing a schematic cross-sectional structure of a semiconductor device when an insulating film is formed without applying a substrate bias. Third
In the figure, for example, An
T! A base pattern 2 in the form of lines is formed, and then a base pattern 2 is formed on the substrate 1.
and Aflli! An insulating film 31 made of, for example, a silicon oxide film is formed using a sputtering method so as to cover the entire surface of the insulating film 112 . Here, the silicon oxide film 31 is
It is formed without applying a bias to the substrate 1. However, in this case, a so-called "neck" portion with poor coverage occurs at the stepped portion of the An interconnect 112, which is the underlying pattern.This defective portion 41 is unavoidable due to the film forming conditions in the sputtering method that does not apply a substrate bias. This was unavoidable and caused dielectric breakdown.

Therefore, a method was proposed in which an insulating film is formed by applying a substrate bias through IJ in order to eliminate the defects shown in FIG. 3 and to fill defective areas with poor coverage.

FIG. 4 is a diagram showing a schematic cross-sectional structure of a semiconductor device in which an interlayer insulating film is formed by applying a relatively strong substrate bias. In FIG. 4, for example, Am is placed on the semiconductor substrate 1.
A base pattern 2, which is a wiring, is formed, and a relatively strong bias voltage is applied to the semiconductor substrate 1 so as to cover the entire surface of the semiconductor substrate 1 and the base pattern 2, thereby forming an interlayer insulation 132, which is, for example, a silicon oxide film. Ru. In this case, as shown in FIG. 4, the defective part with poor coverage is eliminated, but since the silicon oxide film 32 is formed by applying a relatively strong substrate bias, the stress etc. in the silicon oxide rIIA 32 is : Am arrangement where the Am defect is the base pattern! 2, which caused wire breakage.

[Problems to be solved by the invention] As mentioned above, in the conventional interlayer insulating film forming method,
In the sputtering method in which no substrate bias is applied, defective portions 41 with poor coverage occur. In addition, as shown in FIG. 4, when forming the silicon oxide film 32 with a relatively strong substrate bias applied to the semiconductor substrate 1, the Δgloss pattern wA2 is affected by the scratches etc. in the silicon oxide 11132. A defective portion 42 is generated due to An deficiency.

Furthermore, from the vA point of processing capacity, the stronger the substrate bias applied to the semiconductor substrate 1, the more flat the formed silicon oxide 132 can be, but in this case, the speed of forming the interlayer insulating film will decrease. There was a problem.

Therefore, an object of the present invention is to provide a method for manufacturing a semiconductor device that can eliminate the above-mentioned drawbacks and easily obtain an interlayer insulating film free from defects such as so-called "constriction" and AU defects. be.

[Means for Solving the Problems] In the present invention, the advantages and disadvantages of film formation using the conventional sputtering method are considered, and the characteristics of the interlayer insulating film are improved by forming the interlayer insulating film into a multilayer structure. here,
The advantages and disadvantages of conventional sputtering methods are summarized as follows.

(1) Case without substrate bias (1) Advantages: Less stress in the film, strong against Ap- deficiency. In addition, the film formation rate is fast.

(11) Disadvantages Coverage is poor and breakdown voltage is low.

<2)! ! With plate bias (when bias voltage is small) (1) Advantages: Less damage to the substrate by ions, electrons, etc. High pressure resistance.

(11) Disadvantages Coverage is not good.

(3) With substrate bias (when the bias voltage is large) (1) Advantages Good coverage.

(11) Disadvantages: 1~res is large and Am deficiency occurs. Film formation speed is slow.

Therefore, for C1, the underlying pattern (Af
An interlayer insulating film is formed to cover the surface of the semiconductor substrate (1 wiring) and the semiconductor substrate. Next, a substrate bias voltage is applied to further form an interlayer insulating film.

In the specific case [;, the interlayer insulating film is formed by applying a relatively strong blocking voltage.

[Function J] As mentioned above, since the interlayer insulating film is formed using both the step of forming the interlayer insulating film without applying the substrate bias voltage and the step of forming the interlayer insulating film by applying the substrate bias voltage, The above-mentioned advantages of each sputtering method are exploited and the disadvantages are minimized. That is, by forming the layer rtIJ$8 edge film without applying a substrate bias voltage, it is possible to cover the semiconductor substrate and the Am wiring with an interlayer insulating film that is less stressed and resistant to A defects. Therefore, AQ and Afl defects in wiring, which conventionally occur, do not occur. Furthermore, by applying a substrate bias to form an interlayer insulating film, a flat interlayer insulating film with good coverage is formed. The interlayer insulating film formed by applying this substrate bias voltage conventionally caused A standing defects, but in this invention, the AQ and wiring are covered with the interlayer insulating film formed without applying the substrate bias voltage. Therefore, Afl deficiency does not occur.

[Embodiments of the invention] An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a diagram showing a schematic cross-sectional structure of a semiconductor device in which an interlayer insulating film is formed, which is an embodiment of the present invention. In FIG. 1, an Am wiring 2 as a base pattern is formed on a semiconductor substrate 1. As shown in FIG. Next, as a feature of the present invention, a thin interlayer insulating film (silicon oxide film in this embodiment) 31 is formed using a sputtering method without applying a substrate bias so as to cover the entire surface of the semiconductor substrate 1 and the underlying pattern 2. Further, an interlayer insulating film (silicon oxide film in this embodiment) 32 is formed on the silicon oxide film 31 by sputtering while applying a relatively strong substrate bias. Next, a method for manufacturing a semiconductor device, which is an embodiment of the present invention, will be sequentially explained with reference to FIG. First, silicon oxide 1131 is formed on a pattern of AIIL interconnection 112 formed on semiconductor substrate 1 by sputtering without applying a substrate bias voltage. The thickness of this silicon oxide film 31 is small enough to protect the underlying Am wiring 2. Here, care must be taken not to form the silicon oxide film 31 so thickly as to cause poor coverage. Next, silicon oxide 1i32 is formed by applying a relatively strong substrate bias voltage and using a sputtering method.
is formed. Although this silicon oxide film 32 has good coverage, the stress of the film is high. However, since the aforementioned silicon oxide *31 has already been formed, the stress caused by the silicon oxide film 32 does not directly affect the A11-arrangement t12. Therefore, defects such as △ garden defects do not occur.

In the above embodiment, the interlayer insulating film was formed in two stages, but in order to increase throughput, the bias voltage in the bias sputtering method was changed in two stages. An llI/Pi green membrane may be formed.

FIG. 2 is a diagram showing a schematic cross-sectional structure of a semiconductor device according to another embodiment of the present invention. In FIG. 2, silicon oxide 11131 is formed on AJI wiring 2 formed on semiconductor substrate 1 by sputtering without applying a substrate bias voltage. This silicon oxide I
! 31 acts as a protective film as a film that is strong against Al deficiency and has low stress.

Next, a flat silicon oxide film 32 is formed by sputtering while applying a relatively strong substrate bias voltage. Furthermore, in order to increase the withstand voltage and form the film at high speed, the silicon oxide film 33 is formed by sputtering with a relatively weak substrate bias voltage applied. By forming an interlayer insulating film as described above, an interlayer insulating film with good coverage, high breakdown voltage, resistance to stress and AfL defects, and fast film formation rate can be formed. At this time, the drawbacks of each sputtering method are canceled out between each silicon oxide film 31-33, and can be minimized.

Further, in the above embodiment, the A cross line is used as the underlying pattern and the silicon oxide film is used as the interlayer insulating film, but it goes without saying that the scope of application of the present invention is not limited thereto.

[Effects of the Invention] As described above, in the present invention, a multilayer structure can be formed by using a step of forming an interlayer insulating film without applying a substrate bias, and then a step of forming it with a substrate bias applied. Creating. Therefore, the conventional problem of “
Defects such as constrictions and Am defects do not occur, and it is possible to significantly improve the characteristics of the interlayer insulating film and the device characteristics.Furthermore, in this invention, the bias sputtering apparatus itself does not need to be modified in any way. Since it is not necessary to apply a sputtering method, it is possible to easily create an interlayer insulating film with good characteristics using a conventional bias sputtering device.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of a cross-sectional structure of a semiconductor device according to an embodiment of the present invention. FIG. 2 is a diagram showing a schematic cross-sectional structure of a semiconductor device according to another embodiment of the present invention. FIG. 3 is a diagram showing a schematic cross-sectional structure of a semiconductor device having an interlayer insulating film formed by a conventional sputtering method. FIG. 4 is a diagram showing a schematic cross-sectional structure of a semiconductor device having an interlayer insulating film formed by a conventional bias sputtering method. In the figure, 1 is a semiconductor substrate, 2 is an AU wiring, 31 is a silicon oxide film formed by a sputtering method without applying a substrate bias, and 32 is a silicon oxide film formed by a sputtering method with a relatively strong substrate bias voltage applied. , 33 are silicon oxide films formed by sputtering with a relatively weak substrate bias voltage applied, 4
1 is a defective area with poor coverage, and 42 is a defective area due to gloss loss. In addition, in the figures, the same reference numerals indicate the same or corresponding parts. Agent: Masuo Oiwa
) −Hemei 笥

Claims (4)

[Claims] (1) A method for manufacturing a semiconductor device in which an interlayer insulating film is formed on a semiconductor substrate using a sputtering method, wherein a first step is performed in a state where no bias voltage is applied to the semiconductor substrate.
a first step of forming an interlayer insulating film; and a second step of forming a second interlayer insulating film while applying a bias voltage to the semiconductor substrate after the first step. manufacturing method. (2) The semiconductor device according to claim 1, wherein the interlayer insulating film formed in the first step is thinner than the interlayer insulating film formed in the second step. manufacturing method. (3) The second step includes applying a predetermined first bias voltage to the semiconductor substrate to form a corresponding interlayer insulating film, and applying a predetermined first bias voltage different from the first bias voltage to the semiconductor substrate. and applying a bias voltage of 2 to the semiconductor substrate to form a corresponding interlayer insulating film.
A method for manufacturing a semiconductor device according to item 1 or 2. (4) The method for manufacturing a semiconductor device according to claim 3, wherein the first bias voltage is higher than the second bias voltage.