JP2861530B2 - Pattern formation method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for forming a resist pattern, and more particularly to a method for forming a pattern of a positive photosensitive resist and a negative photosensitive resist on the same substrate.

[0002]

2. Description of the Related Art In a conventional pattern forming method for forming a resist pattern, first, a positive type or negative type photosensitive resist is applied on a desired substrate, which is subjected to pattern exposure, and developed with a developing solution. Usually, a resist pattern is formed by performing the process, and a pattern of a positive photosensitive resist and a pattern of a negative photosensitive resist cannot be simultaneously formed on the same substrate.

Accordingly, in order to form two types of resist patterns, a positive resist pattern and a negative resist pattern, on the same substrate, first, only one of the two resist patterns is formed in accordance with the above procedure. After the other resist was applied again, pattern exposure for forming a pattern of only the latter resist was performed, and development had to be performed.

[0004]

According to the conventional method for forming a resist pattern, in order to form a resist pattern of both a positive photosensitive resist and a negative photosensitive resist on the same substrate, coating and patterning are required. Since it is necessary to repeat the process of exposure and development twice, the alignment between the pattern exposure for forming the pattern of the positive photosensitive resist and the pattern exposure for forming the pattern of the negative photosensitive resist is required. This necessitates a problem that a positional error is necessarily generated in the relative positions of the two types of resist patterns.

[0005]

A pattern forming method according to the present invention comprises a step of applying a positive photosensitive resist on a desired substrate, and a step of forming a positive photosensitive resist in a region where a negative photosensitive resist is to be patterned in advance. Subjecting to exposure and development for removal only, and then applying a negative photosensitive resist, and the negative photosensitive resist on the positive photosensitive resist is completely removed, and other portions are removed. and etching with a developer to a negative photosensitive resist has a desired film thickness, then the positive photosensitive cashier
Pattern on the resist and the negative photosensitive resist simultaneously
By performing exposure and developing with the developer,
The positive photosensitive resist and the negative photosensitive resist on the substrate
And simultaneously forming a pattern on the resist .

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be described with reference to the drawings. FIG. 1 is a process sectional view of a pattern forming method according to one embodiment of the present invention.

First, on a desired semiconductor substrate 1, a positive photosensitive photoresist 2 containing a phenolic resin and a dissolving element type photosensitive agent, for example, an ester compound of naphthoquinonediazide and a solvent as main components is about 1 μm to 2 μm. Spin coating is performed so as to have a film thickness (FIG. 1A). Next, of the semiconductor circuit pattern to be formed on the substrate, a positive photosensitive photoresist 2 in a region including a circuit pattern for forming a resist pattern with a negative photosensitive photoresist is included.
To remove several hundred n through the mask pattern 3 in which only the corresponding area is formed of a bright part (light transmitting part).
Exposure is performed to about 200 mJ / cm ² with ultraviolet light of m (FIG. 1B). Then, the photosensitive photoresist 4 irradiated with light is dissolved and removed by performing development for about 1 minute with an alkali developing solution containing a tetramethylammonium aqueous solution (TMAH) as a main component, and the unexposed positive photosensitive photoresist 4 is removed. Only the resist remains on the substrate (FIG. 1 (c)).

Next, a negative photosensitive photoresist capable of forming a pattern with the same alkali developing solution, for example, utilizing a curing reaction of a resin accompanying a dehydration reaction with an acid catalyst comprising a phenolic resin, an acid generator and a crosslinking agent. A non-exposed positive photosensitive photoresist 5 is obtained by adjusting the viscosity of a scientific amplification negative photosensitive photoresist 5 with a solvent so as to have a viscosity of about ten to several tens centipoise (cp) and spin-coating. The thickness of the negative photosensitive photoresist in the region without the positive photosensitive photoresist is sufficiently thick compared to the thickness of the negative photosensitive photoresist in the upper layer region, and is about 1 μm to 5 μm. A state in which the film thickness is obtained can be obtained (FIG. 1D). Next, the alkali developing solution is used for several seconds until the unexposed positive photosensitive photoresist 2 is completely exposed and the negative photosensitive photoresist 5 in the other area has a desired film thickness. Etch for about 10 seconds. By the above-described treatment, a state is obtained in which two types of photosensitive photoresists of a positive type and a negative type are separately applied to a specific substrate for each specific region (FIG. 1E). Here, both resists are simultaneously projected and exposed to ultraviolet light having a photosensitive wavelength on both resists through a mask 7 having a desired shape, and are developed with the alkali developing solution. 2 and the semiconductor circuit pattern formed by the negative resist 6 are simultaneously formed (FIG. 1 (f)).

Here, an example in which a positive photosensitive resist and a negative photosensitive resist in the semiconductor circuit pattern must be used to form a pattern will be described below. A phase shift method (MD Levenson etcl: IEEE) is known as a technique for locally controlling the phase of transmitted light to improve image resolution and optical contrast when forming a projection exposure image in photolithography.
E Trans. Electron Devices,
vol. ED-29, No12, 1828-2836
(1982)), but this is because, by alternately inverting the phase by 180 ° with respect to the adjacent light transmitting portions (bright portions) on the mask, the transmitted light from the adjacent bright portions is bounded by interference. Since the light intensity of the portion becomes zero, an improvement in the resolution and an increase in the depth of focus accompanying an improvement in the optical contrast can be obtained as compared with the case of the same phase.

However, when patterning an isolated line using this phase shift method, as shown in FIG. 2, the isolated line is a dark portion, and a mask in which the mutual phases of the bright portions on both sides are changed by 180 ° is used. It is easiest and most effective to pattern a positive photosensitive resist.

Therefore, when an isolated line and an isolated space portion coexist in a semiconductor circuit pattern to be formed, and each of them is formed by using the phase shift method as described above, the pattern forming method of the present invention is used. It is necessary to form a pattern by selectively using a positive photosensitive resist and a negative photosensitive resist for each region by the method.

Assuming that a resist pattern is formed on a semiconductor substrate having a step having a certain inclination angle, for example, as shown in FIG.
1 is made of a material such as polysilicon which has a non-negligible reflectance with respect to exposure light, and has a film thickness of about 500
About 0 Angstrom, about 0.5μ from the step
The width is about 0.5μ and the height is 1.
When a resist pattern 6 of about 5 μm has to be formed, if this pattern is to be formed with a positive photosensitive resist, the reflected light from the step has an influence on the pattern, but the effect cannot be ignored. When forming a pattern with a resist, the stepped portion is not irradiated with exposure light, so pattern deformation due to reflected light can be ignored. Therefore, it is preferable to form a pattern with a negative photosensitive resist.

Conversely, when a hole or space pattern is formed at a similar position on a substrate similar to that described above as shown in FIG. 4, it is preferable to form a pattern with the positive photosensitive resist 2 for the same reason. Is desirable.

Therefore, even when the situations shown in FIGS. 3 and 4 coexist on the same semiconductor substrate, the negative photosensitive resist and the positive photosensitive resist are selectively used by the pattern forming method of the present invention. By forming a pattern, a desired resist pattern can be formed without being affected by reflection by the underlying substrate.

Alternatively, when a pattern is formed by directly scanning the drawing data with an electron beam or a laser beam on a desired substrate without passing through a mask pattern, the area of the resist pattern remaining is larger than the area to be removed. It is preferable to form a pattern with a positive photosensitive resist and, in the opposite case, with a negative photosensitive resist, since the data amount of drawing data can be reduced.However, the pattern forming method of the present invention is preferable in this case. Is also effective.

[0016]

As described above, according to the present invention, the area to be patterned with a positive photosensitive resist on a desired substrate is a positive photosensitive resist, and the area to be patterned with a negative photosensitive resist is By selectively coating with a negative photosensitive resist, pattern exposure and development of it, it was possible to form both resist patterns at the same time. The resist pattern can be formed without any positional error peculiar to the relative position of the resist pattern.

[Brief description of the drawings]

FIG. 1 is a process sectional view of an embodiment of a pattern forming method according to the present invention.

FIG. 2 is a diagram of a mask using a phase shift method as one embodiment.

FIG. 3 is a view showing a method of forming a resist pattern on a substrate having a step.

FIG. 4 is a view showing a method of forming a resist pattern on a substrate having a step.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Semiconductor substrate 2 Positive photosensitive resist 3 Mask (1) 4 Exposed positive photosensitive resist 5 Negative photosensitive resist 6 Exposed negative photosensitive resist 7 Mask having desired shape 8 Mask dark part 9 Phase Sictar 10 Mask bright part 11 Polysilicon

Claims (4)

(57) [Claims] In a method of forming a resist pattern having a desired shape, a positive photosensitive resist is applied on a desired substrate, and only a region where a pattern is to be formed with a negative photosensitive resist is exposed at a photosensitive wavelength. Removing the positive-type photosensitive resist in the region by developing with a negative-type photosensitive film capable of being exposed to the same wavelength region as the positive-type photosensitive resist and capable of forming a pattern with the developing solution. Applying a positive resist on the substrate, and then completely removing the negative photosensitive resist present as an upper layer in which the positive photosensitive resist is present in a lower layer; and sex until the resist is not present the negative photosensitive resist the region has a desired film thickness, a step straining facilities developed with the developing solution, then the positive photosensitive resist and the Ne Performed simultaneously patterned light exposure type photosensitive resist, by development treatment with the developing solution,
A pattern forming method, wherein a pattern is simultaneously formed on the positive photosensitive resist and the negative photosensitive resist on the substrate. (2) The positive photosensitive resist is pheno
A negative-type photosensitive resin having a melting point resin and a dissolving element type photosensitive agent.
The photosensitive resist is crosslinked with the phenolic resin and an acid generator.
A crosslinking agent, wherein the developer is tetramethylammonium
Characterized as an alkaline developer mainly composed of an aqueous solution
The pattern forming method according to claim 1, wherein (3) Pattern exposure using a phase shift method
2. The pattern forming method according to claim 1, wherein
Law. (4) Formed near the step on the semiconductor substrate
A resist where the resist pattern selectively remains after exposure and development
In the case of a negative photosensitive resist,
Is formed near the step on the same substrate.
Resist pattern after exposure and development
Holes or spaces obtained by removing
When using a positive photosensitive resist, this pattern is used.
2. The pattern according to claim 1, wherein the pattern is formed by turns.
The method of forming the blade.