JPH0237352A - Pattern forming method - Google Patents

Abstract

PURPOSE:To enable a desirable pattern to be formed without accumulating excess nitrogen in an interface between a substrate and a photoresist at the time of exposure by forming the resist on the substrate so as to render the content of a photosensitive agent near the interlayer lowest in the resist. CONSTITUTION:The photoresist 8 is formed on the substrate 1 so as to render the content of a photosensitive agent near the interlayer lowest in the resist in the first process and the resist 8 is exposed and developed to form the desired pattern in the second process, thus permitting nitrogen not to be produced in excess near the interlayer between the substrate 1 and the resist 8 due to the lowest content of the agent, consequently, the resist 8 not to rise and no to cause shearing like the conventional cases, and a desired pattern to be obtained by development.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a pattern forming method performed using photolithography in a semiconductor device manufacturing process.

[Conventional technology]

FIG. 4 is a cross-sectional view showing the steps of a conventional pattern forming method performed using photolithography. A positive photoresist 2 is formed on the substrate 1 .

As shown in FIG. 4(a), when the photoresist 2 on the substrate 1 is irradiated with exposure light (for example, ultraviolet light) 3, the photoresist 2 generally contains nitrogen atoms (N).
Nitrogen (N2) 4 is generated within the photoresist 2 by a chemical reaction between the nitrogen atoms and the exposure light 3. The nitrogen 4 generated in excess in this way is accumulated at the interface between the substrate '1 and the photoresist 2, as shown in FIG. A part becomes the raised area 5. Furthermore, as shown in the same figure (C), when the pushing pressure exceeds the cohesive force of the photoresist 2 film itself, the photoresist 2
A shear 6 is generated.

[Problem to be solved by the invention]

The conventional pattern forming method is performed through the steps described above, and the nitrogen 4 accumulated at the interface between the substrate 1 and the photoresist 2 during exposure creates shear 6 in the photoresist 2, and even if developed, this There was a problem in that the shearing 6 caused pattern defects as shown in FIG. 4(C) (the normal pattern is the dotted line), making it impossible to obtain a desired resist pattern.

The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a pattern forming method in which excessive nitrogen does not accumulate at the interface between a substrate and a resist during exposure.

[Means to solve the problem]

The pattern forming method according to the present invention includes the steps of forming a photoresist on a base so that the content of a photosensitive agent is minimized near the interface with the base, exposing and developing the photoresist, and The structure includes a step of forming a photoresist into a desired pattern.

[Effect]

In this invention, the photosensitizer content of the photoresist is minimized near the interface between the base and the photoresist, so that excessive nitrogen is not generated near the interface between the base and the photoresist during exposure. Excessive nitrogen accumulation at the resist interface does not occur.

〔Example〕

FIG. 1 is a sectional view showing the steps of the pattern forming method according to the present invention. The difference from the conventional example shown in FIG. 4 is that a positive type photoresist containing a small amount of photosensitizer is provided between the substrate 1 and the photoresist 20.

A photoresist 7 is formed on the substrate 1 using a spin code (FIG. 1(a)). Thereafter, a photoresist 2 with a high content of photosensitizer is formed on the photoresist to form a two-layer structure (FIG. 1(b)).
The reason why the photosensitive material content of only photoresist 7 was reduced without reducing the photosensitive material content of both photoresist 7 was to prevent the exposure sensitivity from decreasing.

FIG. 2 shows the distribution of nitrogen 4 when the photoresist thus formed is irradiated with exposure light 3 to form a pattern.

From Figure 2, the number of nitrogen 4 generators in the photoresist store is 7.
It can be seen that it is less than that of Otoresist 2-. Generally speaking, there is a proportional relationship between the photosensitizer content of photoresist and the amount of nitrogen 4 generated when 7-otoresist is irradiated with exposure light 3, and the photoresist content of photoresist 7 is higher than that of 7-otoresist 2. Based on less. As mentioned above, since the generation of nitrogen 4 in the photoresist is small, nitrogen 4 is not accumulated excessively at the interface between the substrate 1 and the photoresist as in the conventional case, and the raised region 5 (Fig. 4 (b)
) does not occur. Therefore, shearing does not occur as in the conventional case, and a desired pattern can be obtained upon development.

FIG. 3 is a diagram showing another embodiment of the invention. In this embodiment, unlike the above embodiments, only one layer of 7 photoresist 8 is provided on the substrate 1, as shown in FIG. 3(a). When the thickness of the photoresist 8 is measured with reference to the substrate 1, the thickness of the photoresist 8 and the photosensitive agent content are proportional to each other as shown in FIG. 3(b).

Specifically, a resist containing no photosensitive agent is formed on the substrate 1, and then the photosensitive agent is diffused from the surface to form the photoresist 8.
form. Even with this configuration, as mentioned above, there is a proportional relationship between the content of the photosensitizer and the amount of nitrogen 4 generated, so that excessive nitrogen 4 is not generated near the interface between the substrate 1 and the photoresist 8 during exposure. First, the same effects as in the above embodiment can be obtained. Note that the photosensitizer content of the photoresist 8 should be the smallest near the interface between the substrate 1 and the photoresist 8, and does not necessarily have to be in the ratio W4 relationship with the thickness of the photoresist 8 as described above.

In the above embodiments, the case where the photoresist is positive type is explained, but the same effect can be obtained also when the photoresist is negative type. In other words, it is possible to prevent the photoresist that should remain as a pattern from peeling off before development.

(Effects of the Invention) As described above, according to the present invention, since the photoresist is formed on the base so that the content of the photosensitizer is minimized near the interface with the base, the base and photoresist are separated during exposure. Excessive nitrogen is not generated near the interface between the substrate and the photoresist, and nitrogen is not accumulated excessively at the interface between the underlayer and the photoresist. As a result, unlike in the prior art, the 7-otoresist does not bulge and shear does not occur, so there is an effect that a desired pattern can be formed by development.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing one embodiment of the present invention, FIG. 2 is a diagram for explaining the state of nitrogen generation during exposure, FIG. 3 is a diagram showing another embodiment of the invention, and FIG. The figure is a diagram showing the steps of a conventional pattern forming method. In the figure, 1 is a substrate, 2 and 7 are positive photoresists, and 3 is exposure light. Note that the same reference numerals in each figure indicate the same or corresponding parts.

Claims (1)

[Claims] (1) Forming a photoresist on a base so that the content of the photosensitive agent is minimized near the interface with the base, and exposing and developing the photoresist to form a desired pattern into the photoresist. A pattern forming method comprising a step of forming a pattern.