JPH04110854A - Method for applying photoresist film - Google Patents

Abstract

PURPOSE:To eliminate the misalignment within a substrate surface and to form resist patterns with high accuracy by applying and forming a photoresist film on a substrate, then applying ultrasonic oscillations to the substrate. CONSTITUTION:After the photoresist 2a is applied and formed by a spin coating method on the semiconductor substrate 1, the ultrasonic oscillations 3 are applied to the substrate 1 to finely oscillate the resist 2a, by which the coverage to the repeating patterns of the ruggedness as alignment mark parts 7 previously formed within the surface of the substrate 1 is symmetrized as far as possible. The resist 2a subjected to the excitation treatment is subjected to a prebaking treatment to form a resist film 2. The film 2 is then projected and exposed with mask patterns 4 by UV rays 5 and is subjected to printing, transferring and development processing, by which the resist patterns 6 are formed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for coating a photoresist film, and more specifically, to an improvement in a method for coating a photoresist film in the manufacture of semiconductor devices and the like.

[Prior Art] In the manufacturing of semiconductor devices, patterns for forming each part of the device are becoming finer as the trend toward higher density integration progresses. There is a tendency to increase the diameter of semiconductor substrates to efficiently manufacture all kinds of semiconductor devices, and for this reason,
2. Description of the Related Art In manufacturing processes and manufacturing apparatuses applied to conventional element formation, many efforts have been made to uniformly process the entire surface of a semiconductor substrate.

FIG. 3 is a cross-sectional view sequentially showing the main process of forming a resist pattern using photolithography in the conventional manufacturing of this type of semiconductor device.

In the case of resist pattern formation by photolithography in the conventional manufacturing process of semiconductor devices, basically a photoresist 2a is applied and formed on a required surface such as the main surface of the semiconductor substrate 1 (see FIG. 3). a))
After prebaking the photoresist 2a to form a resist film 2 (FIG. 3(b)), a desired mask pattern 4 is formed on the prebaked resist film 2 with ultraviolet rays 5 using a necessary exposure device. By projecting exposure, printing is transferred (FIG. 3(C)), and development processing is performed, a desired resist pattern 6 is formed (
This is done as shown in Figure 3(d)).

However, spin coating is mainly used to coat and form the photoresist [2a on the semiconductor substrate 1 plane/\\, and in coating by this spin coating, relatively flattening is not achieved. When forming the photoresist 2a on the surface of the substrate 1, the uniformity of the formed film thickness is good, and performance has already been achieved to maintain accuracy within ±1% of the reference value. This is said to be an effective means for forming the resist pattern 6 in S.

Moreover, reduction projection exposure apparatuses (hereinafter referred to as steppers) are currently the mainstream exposure apparatus used for printing the mask pattern 4 onto the resist film 2 after the prebaking process, and according to this stepper, Since the mask pattern 4 can be projected in a reduced size and exposed within a small area, the uniformity within the surface of the substrate is quite good.

[Problems to be Solved by the Invention] However, in the conventional coating method of the photoresist film formed as described above, the photoresist is coated and formed on the base substrate including the stepped portion by a similar spin coating method. In this case, the coverage of the resist film is not necessarily uniform between the center of the substrate, which is relatively flat, and the periphery of the substrate, where a concave-convex pattern for alignment is formed. Specifically,
There was a problem in that the amount of alignment deviation varied within the same substrate surface.

That is, as shown in FIG. 4(a), the coverage of the photoresist in the alignment mark portion 7 is as shown in FIG. 4(a). In the case of a concave-convex pattern perpendicular to the photoresist flow direction 8, the resist film thickness tends to be thicker on the outside of the convex pattern, and similarly the resist film thickness tends to be larger on the inner side of the concave pattern. As a result, the alignment signal 9a taken in from the alignment mark section 7 for exposure processing has an asymmetrical waveform as shown in FIG. On the stepper side, the relative position between the substrate and the mask is incorrectly recognized, and the exposure is performed at a position shifted from the pattern in the previous process.

This invention was made to solve these conventional problems, and its purpose is to eliminate misalignment within the substrate surface and create a highly accurate and reliable resist pattern. I made it possible to obtain. An object of the present invention is to provide a method for coating this type of photoresist film.

[Means for Solving the Problems] In order to achieve the above object, the photoresist film coating method according to the present invention includes applying and forming a photoresist film on a substrate surface by a spin coating method, and then applying ultrasonic waves to the substrate. It is designed to give vibration.

That is, in the process of coating and forming a photoresist film on the surface of a semiconductor substrate by a spin coating method, and performing prebaking, exposure, and development processing to obtain a resist pattern, the present invention provides a process in which a photoresist film is coated on a semiconductor substrate surface by a spin coating method, and a resist pattern is obtained by prebaking, exposing, and developing the photoresist film. , a photoresist film coating method characterized in that prior to pre-baking treatment, ultrasonic vibration is applied to the substrate.

[Function] Therefore, in the method of the present invention, after a photoresist film is applied and formed, the applied photoresist film itself vibrates with the ultrasonic vibration applied to the substrate, and the flow of the photoresist during spin coating is affected. The film thickness of the photoresist can be made uniform regardless of the direction.

[Example] Hereinafter, an example of the photoresist film coating method according to the present invention will be described in detail with reference to FIGS. 1 and 2.

FIGS. 1(a) to 1e) are cross-sectional views schematically showing the outline of the main steps of forming a photoresist film to which an embodiment of the method of the present invention is applied, and FIGS. (b) is an explanatory diagram showing a photoresist film formed by the above method and an alignment signal obtained from the photoresist film, and the first
In the embodiment shown in FIGS. 3 and 2, the same reference numerals as in the conventional example shown in FIGS. 3 and 4 indicate the same or corresponding parts.

That is, in the embodiment method shown in FIGS. 1 and 2, first, a photoresist 2a is coated and formed on the main surface of the semiconductor substrate 1 by spin coating (see FIG. 1(a)). )), apply ultrasonic vibration 3 to the semiconductor substrate 1 from a suitable ultrasonic generation source (FIG. 1(b)).
By finely vibrating the photoresist 2a coated in the previous step, coverage is obtained for the repetitive pattern of concave and convex portions as the alignment mark portion (FIG. 2(a)) 7 previously formed within the surface of the semiconductor substrate. The photoresist 2a subjected to the vibration treatment is then prebaked to form a resist film 2 (FIG. 1C), and then, as in the conventional method, By projecting and exposing the desired mask pattern 4 onto the prebaked resist film 2 with ultraviolet rays 5 using a necessary exposure device, the baking is transferred (FIG. 1(d)), and by developing, A desired resist pattern 6 is formed (FIG. 1(e)).

Therefore, in the photoresist film coating method of this embodiment, which is processed as described above, after the photoresist film 2a is coated and formed by the spin coating method, the photoresist film 2a is applied to the substrate 1 by ultrasonic vibration 3. The photoresist film 2a itself vibrates, and the thickness of the photoresist film 2a changes completely regardless of the flow direction 8 of the photoresist during spin coating (FIG. 2(a)). As a result, it becomes possible to achieve symmetrical coverage at the alignment part 7, which consists of a repeated uneven pattern, and the difference in coverage between the center of the board and the periphery of the board is eliminated, and even the same board can be In-plane misalignment can be improved very easily.

[Effects of the Invention] As detailed above, according to the method of the present invention, after a photoresist film is applied and formed by spin coating, the applied photoresist film itself is damaged by ultrasonic vibrations applied to the substrate. It is vibrated and can equalize the film thickness of the photoresist regardless of the direction of flow of the photoresist during spin coating, and can provide coverage for the repeated uneven pattern on the underlying substrate surface. It has the advantage that it can be made symmetrical, and there is no difference in coverage between the center and periphery of the substrate (therefore, misalignment during exposure in the post-process can be eliminated, and At the same time, the stress in the resist film due to spin coating is alleviated by the applied ultrasonic vibrations, and the adhesion between the resist pattern and the substrate after development can be improved. This method has excellent features such as being extremely easy and simple to implement since it only applies sonic vibrations.

[Brief explanation of the drawing]

1(a) to 1(e) are cross-sectional views schematically showing the outline of the main steps of forming a photoresist film to which an embodiment of the method of the present invention is applied, and FIGS. 2(a) to 2(b) are respectively sectional views.
) are explanatory diagrams showing a photoresist film formed by the same method as above and an alignment signal obtained from the photoresist film, respectively, and FIG. 3(a)
4 to d) schematically show the outline of the main forming steps of a photoresist film according to a conventional example.
Figures (a) and (b) are explanatory views showing a photoresist film formed by the above method and an alignment signal obtained from the photoresist film, respectively. 1... Semiconductor substrate, 2a... Photoresist, 2... Prebaked resist film, 3...
・Ultrasonic vibration, 4...mask pattern, 5...
・Ultraviolet light, 6...Resist pattern, 7...Alignment mark section,...Direction of flow of photoresist, alignment signal.

Claims (1)

[Scope of Claims] In the step of applying and forming a photoresist film on a semiconductor substrate surface by a spin coating method, and performing pre-baking, exposure and development processing to obtain a resist pattern, after the photoresist film is applied and formed by the spin coating method. . A method for coating a photoresist film, comprising applying ultrasonic vibration to the substrate prior to pre-baking.