JPS59155930A - Forming method of minute pattern - Google Patents

Abstract

PURPOSE:To obtain a reversely inclined layer of a minute pattern fitted to a lift-off through one-time ultraviolet beam irradiation without generating an excessive boundary layer by laminating and forming a photosensitive film as a first layer and a photosensitive film as a second layer, a kind thereof is the same as the film but a gamma value and sensitivity thereof differ, on a semiconductor substrate and beam-transferring and developing the surface. CONSTITUTION:A first positive type resist layer 12 photosensitized to far ultraviolet beams is applied on a semiconductor substrate 11 as a photosensitive film as a first layer, and a second positive type resist layer 13, a kind thereof is the same as the layer 12 but a gamma value and sensitivity thereof are lower, is laminated and applied onto the layer 12. A solvent contained in these layers is evaporated at a proper temperature, ultraviolet beams 15 are irradiated through mask patterns 14, and resists in exposed sections are removed through development. Accordingly, development advances up to the layer 12 from the layer 13 while intruding to the inside of the layer 12, and reversely inclined layers effective for a lift-off are obtained, thus preventing the generation of an excessive boundary layer between the layers 12 and 13.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a method for forming fine patterns in the manufacturing process of semiconductor devices.

[Prior art]

An example of a conventional method for forming fine patterns of this kind is shown in FIGS. 1 to 3. That is, as shown in Fig. 1, first, a first resist layer (2) sensitive to far ultraviolet light such as PMMK (trade name) is coated on a semiconductor substrate (1), and the solvent is evaporated at an appropriate temperature. Thereafter, a second resist layer (3) sensitive to ultraviolet light such as product name AZ1350J is applied thereon, the solvent is similarly evaporated at an appropriate temperature, and a mask pattern (4) is applied thereto. UV light (5) is irradiated through the resist film, and the resist in the exposed area is removed by development. Now apply PMMK to each resist layer (2) and (3) as described above. When using AZ1350J,
An insoluble layer (6) is formed at the boundary between these two layers, so as shown in Figure 2, the exposed part of this insoluble layer (6) is removed using O, plasma (7), etc. Then, by irradiating this with far ultraviolet light (8) and developing it, the third
As shown in the figure, the first resist layer (2) digs into the lower part of the remaining second resist layer (3) and is developed, resulting in a reversely sloped layer suitable for lift-off.

However, in this conventional method, it is necessary to irradiate ultraviolet light and far ultraviolet light twice, and also to irradiate the first and second
Depending on the combination of resists, an indissolved layer may be formed, resulting in the inconvenience that another process must be added to remove this insoluble layer.

[Summary of the invention]

In view of the above-mentioned drawbacks of the conventional resists, the present invention has been developed by overlapping the same type of resists with different characteristics as the first and second resist layers, thereby eliminating the formation of an extra boundary layer and making it possible to It is possible to obtain a reversely sloped layer that is effective for lift-off by irradiating UV light at a high temperature.

[Embodiments of the invention]

Hereinafter, one embodiment of the method of this invention will be described in detail with reference to FIGS. 4 and 5.

As shown in Fig. 4, first, a first positive resist layer such as AZ type is applied as the first photosensitive film on the semiconductor substrate (11), and the solvent is evaporated at an appropriate temperature. After that, a second layer of photosensitive coating is applied thereon, which is of the same type as the first resist layer σ2, but also has a lower γ value and lower sensitivity, that is, a positive resist layer with different characteristics. 2. Apply a resist layer α, evaporate the solvent at an appropriate temperature, irradiate it with ultraviolet light (15+) through a mask pattern (14), develop it, and remove the resist in the exposed area. do.

Due to this operation, the first resist layer (one is the second resist layer), and since its γ value and sensitivity are high, development is performed from the second resist layer ← to the first resist layer ( 12
As it penetrates into the inside of the layer, as shown in Figure 5, a reverse slope layer that is effective for lift-off is obtained.
At this time, these first and second resist layers (J2)
, (13, since both layers are of the same type, no extra boundary layer is formed.

In the above embodiments, an AZ-based positive resist was used as the photosensitive film, but it goes without saying that similar effects can be obtained with other resists.

〔Effect of the invention〕

As detailed above, according to the method of the present invention, since the same type of photosensitive coatings with different characteristics are used for the first layer and the second layer, an unnecessary boundary layer is not formed between the two layers, and moreover, By exposure and development, a reversely sloped layer suitable for lift-off can be obtained, and therefore, the number of steps required for forming fine patterns can be reduced, and pattern accuracy can be improved.

[Brief explanation of the drawing]

1 to 3 are cross-sectional views showing a conventional method for forming a fine pattern in order of process, and FIGS. 4 and 5 show a method for forming a fine pattern according to an embodiment of the present invention in order of process. Each is a sectional view. αυ... Semiconductor substrate, (12... First resist layer (first layer photosensitive coating), (13... Second resist layer (second layer photosensitive coating), Q→ ...Mask pattern, shouting...ultraviolet light. Agent Shin Kuzuno - KuchiotsuZ η
=2 Ward, 14

Claims (1)

[Claims] After forming a first layer of photosensitive coating on a semiconductor substrate, a second layer of photosensitive coating is formed thereon, which is the same type as the first layer of photosensitive coating but has different characteristics such as γ value and sensitivity. let me,
A method for forming a fine pattern, which is characterized in that the pattern is then phototransferred and developed.