JPS5898942A - Forming method for ultrafine pattern - Google Patents

Abstract

PURPOSE:To obtain an ultrafine pattern by the steps of etching to allow the film to become the second pattern to remain only on the side surface of the first master pattern and etching the base material with the film as a mask. CONSTITUTION:The pattern 2 of a nitrided film is formed by photoetching on an Si substrate 1, and an oxidized film 3 is accumulated. Subsequently, the film 3 is etched by reactive sputter etching with Freon gas without side etching in the thickness of the film 3, thereby forming the etching remainder of the oxidized film only on the side surface of the pattern 2. Thereafter, a nitrided film 5 is removed with phosphoric acid, and the remainder 4 of the etched oxidized film is allowed to remain as an ultrafine pattern. With the film 4 as a mask the Si substrate is etched, thereby obtaining an ultrafine Si pattern 6.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an etching method for forming an ultra-fine pattern on the contour of a mask pattern, and a method for insulating and isolating silicon elements using the etching method.

Photoetching is used as a method for forming fine patterns in conventional semiconductor manufacturing processes.

Recently, X-ray exposure and electron beam exposure have been used as resist exposure methods to form patterns of 1 μm or less, but it is difficult to realize ultra-fine patterns of 0.1 μm or less.

OBJECTS OF THE INVENTION The main object of the present invention is to provide a novel pattern forming method that can realize ultra-fine patterns of 1 μm or less to about 0.01 μm.

General description of the invention That is, the present invention includes an etching process that leaves a film (911, oxide) that will become a second pattern only on the side surface of a first mask pattern (for example, a nitride film); This pattern forming method consists of the steps of removing the first mask pattern by attacking the film that will become the second pattern, and etching the underlying material by using the remaining film that will become the second pattern as an etching mask.

Hereinafter, the present invention will be explained in detail with reference to Examples.

Example 1 FIG. 1 shows the etching process of a 3i substrate according to the present invention. A pattern 2 of a nitride film (Si3N4) is formed on a Si substrate 1 by photoetching, and an oxide film 5 (
B) Obtain the shape shown in the figure by depositing stotta. Here, the etching of nitride@2 is performed by reactive sputter etching using Freon gas, the side surfaces of the nitride film pattern are kept vertical, and the deposition of oxide film 3 is performed using CVD (Chem.
jcalyapour peposition)
A film is formed isotropically. Next, by reactive sputter etching using Freon gas, the oxide film 3 is etched by the film thickness without side etching, so that the remaining oxide film 4 is formed only on the sides of the nitride film pattern 2, as shown in (). After this, when the nitride film 5 is removed with t-IJ hydrofluoric acid, the etched oxide film 4 remains as an ultra-fine pattern.When the 3i substrate is etched using this oxide film 4 as a mask, el
An ultrafine Si pattern 6 is obtained as shown in FIG. 81 above
When etching the substrate, Br can be etched according to the dimensions of the oxide film pattern 4 by using a reactive sputter etching method using a mixed gas of CCZ and OI.

In the above etching, an ultra-fine pattern is formed on all the contours of the initial nitride film pattern, but after the ultra-fine pattern of the oxide film is formed, unnecessary oxide film patterns can be removed by photo-etching, and then Si etching can be performed. Of course it is possible.

Embodiment 2 FIG. 2 shows a comb-shaped etching process of a Si substrate according to the present invention. First, as shown in (A), the side surface of the oxide film (8iot) pattern 11 is coated with nitride [1(S)] in the same manner as in Example 1.
'3N4) fine pattern 12 is left. After removing the oxide film 11 with a hydrofluoric acid solution, the same process is repeated again to form a fine pattern 13 of the oxide film as shown in (b).
leave. When Si is etched using this oxide film as a mask, a Bi pattern 14 arranged in a comb shape as shown in eS) is formed.
get.

FIG. 3 shows the insulation isolation process of a 3i element using the above-mentioned comb-shaped B+ pattern. First, as shown in (a), an oxide film (Sift) is formed in stripes on the entire surface of the Si substrate by the above method.
After placing the fine butter 721, the f3i element pattern 22 is placed thereon using photoresist. Subsequently, when the Si substrate is etched, as shown in (b), except for the Si element pattern 23, K is 3i with a comb-shaped cross-section.
A pattern 24 is formed. After doing this, Photoregis 1
-2z and the oxide film are removed, and the entire comb-shaped 81t'4E is Sin! When thermal oxidation is carried out until it can be converted to sho, an insulating isolation region 25 filled with sho can be formed as shown in el due to volume expansion due to thermal oxidation. In addition,
Here, the ratio of the comb-shaped Si pattern width to its spacing is 9:11.
By doing so, a substantially flat insulation isolation region can be formed.

FIG. 4 shows an insulation isolation structure in which the width of the comb-shaped Si pattern is made much smaller than the spacing thereof.

Since the width of the 3i pattern is small, the insulation isolation region is not filled even after the thermal oxide film 31 is formed, and sio, (1d8i, N4.Po1)'Si) 32 is subsequently deposited and filled. In this case, by reducing the width of the comb-shaped Si pattern, the endless layer 1131 can be made thinner.
The amount of penetration of the oxide film into the element formation region 33 can be reduced. Furthermore, in filling the insulation isolation region with the deposited film 32, since the comb-shaped 3i0°34 divides the trench, it is possible to make the deposited film 32 filling the trench thinner than in the case where there is no comb-shaped sio. Therefore, the flat V+ after filling increases.

As explained above, by applying the present invention, ultra-fine patterns can be formed with an accuracy of about 0.01 μm depending on the thickness of the deposited film. Furthermore, if an ultra-fine Si pattern is formed in a comb shape, a flat insulating isolation region can be easily formed by thermal oxidation alone or by forming a deposited film thereon.

Note that the ultrafine pattern forming method of the present invention can be applied to various base materials. For example, as a base material, po
lyst, to st* If you select 8'MNa e A', you can perform the process of PI 1 by selecting these etching mask materials for the deposited film.

In addition, when applying unevenness to the base material, 1. Phospho 5ilicate Qlass
), etc., to form an ultra-fine pattern on the phosphor glass, etc., and then etching is performed to transfer the pattern to the base.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing the etching process of the present invention, FIG. 2 is a cross-sectional view showing the comb-like etching process of the present invention, FIG. 3 is a cross-sectional view showing the insulation separation process of the present invention, and FIG. FIG. 3 is a cross-sectional view of an example of a separation structure. 1...Si substrate, 2.5...Nitride film, 3...Oxide film, 4V]Z Figure ￥J 1 Figure 3 9 乃JJ Jiko

Claims (1)

[Claims] 1. An etching process that leaves a film that will become the second pattern only on the side surface of the first mask pattern; 1. A method for forming an ultra-fine pattern, comprising the steps of: removing a first mask pattern; and etching a base material using the remaining film forming the second pattern as an etching mask.