JPS59115543A - Forming method for coating film - Google Patents

Abstract

PURPOSE:To obtain a flat insulating film even on a semiconductor substrate which has an irregular surface by forming a wiring layer of the prescribed pattern on the substrate, coating a thin film when coating the entire surface including the wiring layer with an insulating film, removing only a surface layer, and again covering with a thin film, thereby sequentially setting in the prescribed thickness. CONSTITUTION:An aluminum wiring layer having approx. 1mum of thickness is formed on a semiconductor substrate 11, and an SiO2 film 13 similarly having approx. 1mum of thickness is coated by sputtering on the overall surface including the layer 12. The coating of the film 13 at this time is not simultaneously performed, but the film 13a having several 100Angstrom is first coated, is then vertically etched by an ion milling method, and the surface layer is removed in the thickness of approx. 200-300Angstrom . The thickness thus removed is the value on the flat surface, but the layer 12 is vigorously etched, and the exposed end part is almost removed. Therefore, the film 13b having several 100Angstrom is again laminated and coated by the sputtering method, and part is again removed. After such operation is repeated several tens times, and a smooth film 13 is then produced on the overall surface.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field of the Invention The present invention relates to a method of forming a deposited film, and more particularly to a method of forming a flat deposited film on an uneven substrate surface.

(b) Prior art and problems For example, when manufacturing semiconductor devices such as semiconductor integrated circuits (ICs), a large number of semiconductor elements are provided on a semiconductor substrate, and in order to connect these elements, multiple semiconductor devices are placed on the substrate surface. The wiring layers are formed in multiple layers. In this case, the semiconductor substrate has unevenness due to the formation of semiconductor elements, and when wiring layers and insulating films are alternately laminated on the surface, the unevenness becomes even more severe and the steps become thicker, causing disconnections and short circuits in the wiring layer. It is known that this is more likely to occur.

FIG. 1 shows an example of its cross-sectional view, and 1 is a semiconductor substrate.

2 is the wiring layer, 3 is the insulating film, C is the part that is prone to disconnection, and S
is a part that is easily short-circuited. To this end, various methods have been proposed to flatten the surface by devising the deposition method and post-deposition processing method, but all of these methods require delicate preparation and do not necessarily provide good reproducibility. This method cannot achieve flattening and is dependent on the surface shape.

(e) Object of the Invention The present invention proposes a forming method that eliminates these drawbacks and stably flattens the surface of the deposited film.

(dl)Structure of the Invention The object is achieved by a method of forming a deposited film in which the steps of depositing a thin film and then etching a part of the film thickness are repeated until the desired thickness is reached.

(e) Embodiments of the Invention Hereinafter, an embodiment in which an insulating film made of a silicon dioxide film is laminated on an aluminum wiring layer will be described in detail with reference to one drawing. 2 to 6 show cross-sectional views of the process according to the present invention, of which FIGS. 2 to 5 are partial process views of the repeated steps of deposition and etching;
The figure is a cross-sectional view of the film coated to the required thickness.

On the aluminum wiring layer 12 with a thickness of 1 μm provided on the semiconductor substrate 11, silicon dioxide (S
i02) When trying to stack the film 13 by sputtering,
First, as shown in Figure 2, the film thickness is several hundred layers (1000 Å).
5i02 H@13a (below) is applied. Then,
As shown in FIG. 3, the film thickness of 200 to 300 layers (a fraction of the deposited film thickness) is etched away by ion milling.

In the ion milling method, vertical etching is performed, and the above etching film thickness of 200 to 300 mm is the etching thickness on a flat surface, and the protruding parts (on the wiring layer 12) are violently etched, and the film thicker than this is etched away. be done. And it becomes the tip part state of the side surface.

Next, as shown in FIG. 4 again, a 5i02 film 13b having a thickness of several hundred layers is deposited by sputtering. Then, the 5i02 film is formed thicker on the semiconductor substrate 11 than on the wiring layer 12 together with the previous deposition, and the 5i02 film is the thinnest (formed) at the end of the side surface. The film thickness is 20% by ion milling method.
When 0 to 300 layers were removed by etching, a large amount of the SiO2 film was removed on the wiring layer 12 as shown in FIG. It is formed in the state shown.

By repeating this process several to several times, the surface becomes smooth 5i as shown in Figure 6.
02 film 13 can be formed.

In FIG. 6, there are still irregularities on 5i021%13, but if it is made thicker, it will become a flat surface.

The above is the gist of the forming method according to the present invention, but in such a forming method, it is desirable to perform deposition and etching alternately within one reaction apparatus, and an example of an outline of the apparatus is shown in FIG. . That is, the left side is the sputtering device 21, and 5i
02 Hit the target 22 with argon ions and remove the substrate 23.
A 5i02 film is deposited on top. On the right side is an ion milling device 25, in which argon ions emitted from a plasma generator 26 are accelerated to etch the surface of the substrate 23, and when the table 30 on which the substrate is placed is rotated, for example, every two minutes, the above-mentioned etching process is performed. Forming methods can easily be alternated.

Note that these reactions are carried out under reduced pressure, but the exhaust system is not shown.

The above is an example in which the film is deposited by sputtering and etched by ion milling, but it can also be formed using other deposition methods (e.g., plasma vapor phase epitaxy) or etching methods (e.g., active ion etching). can. Furthermore, it goes without saying that not only the insulating film but also the wiring layer can be planarized in the same manner.

(f) Effects of the Invention As is clear from the above explanation, the present invention is a method for forming a flat deposited film on a surface with unevenness, and the surface can be flattened regardless of the shape of the unevenness. This makes a significant contribution to improving the quality of semiconductor devices.

[Brief explanation of drawings]

Figure 1 is a cross-sectional view of a conventional multilayer wiring layer and its problems, Figures 2 to 6 are cross-sectional views of the wiring layer according to the present invention in the order of steps, and Figure 7 is a diagram showing the formation method of the present invention applied. FIG. In the figure, 1 and 11 are semiconductor substrates, 2.12 are wiring layers, 3,
13, 13a, 13b are insulating films, 21 is a sputtering device,
25 is an ion milling device, 30 Fig. 1 Fig. 2 Fig. 5 Fig. 6 Fig. 7 Fig. 3 ura]
1-Ministry, 1st section with 1'1 11th'
11 people Esho Kami ≦・Uchiken Kawasaki 11 Kawari 1;l+z l:
111th grade】015+(522) Name Fujitsu Limited

Claims (1)

[Claims] 1. A method for forming a deposited film, which comprises repeating the process of depositing a thin film and then etching a part of the film thickness until the desired thickness is reached.