JP2007073685A - Resist pattern forming method and baking apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a resist pattern forming method and a baking apparatus which reduce the line edge roughness without changing the pattern dimensions. <P>SOLUTION: The resist pattern forming method executes a baking, exposing, after baking, developing, rinsing and drying steps to form a resist pattern after coating a substrate 11 under process with a chemical sensitization type resist. On baking after exposure, the substrate 11 under process is laid in an atmosphere with an electric field parallel to the surface of the substrate 11, and relatively varying its direction over time. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a resist pattern forming method, and more particularly to a resist pattern forming method in which post-exposure baking is improved. Furthermore, it is related with the baking apparatus used for this resist pattern formation method.

  In recent years, with the high integration of LSIs, the pattern of semiconductor elements is becoming increasingly finer, and the resist pattern for forming semiconductor elements is also becoming finer. Along with the miniaturization of the pattern size of the semiconductor element, the line edge roughness of the resist pattern has become a problem.

When line edge roughness exists in the resist pattern, it becomes a factor of deteriorating semiconductor element characteristics. As an example of reducing the line edge roughness of the resist pattern, there is a method of performing reflow baking after forming the resist pattern (see, for example, Patent Document 1). However, this type of method has a problem that the pattern dimensions change before and after the processing.
JP 2001-332484 A

  As described above, in the conventional resist pattern forming method, the edge roughness becomes a problem as the pattern dimension is reduced. In order to prevent this, the reflow baking method causes a problem that the pattern dimension changes.

  The present invention has been made in view of the above circumstances, and an object thereof is to provide a resist pattern forming method capable of reducing line edge roughness without causing a change in pattern dimension. is there. Another object of the present invention is to provide a baking apparatus for use in the resist pattern forming method.

  In order to solve the above problems, the present invention adopts the following configuration.

  That is, one embodiment of the present invention is a method of forming a resist pattern by applying a chemically amplified resist on a substrate to be processed and performing post-application baking, exposure, post-exposure baking, development, rinsing, and drying. The post-exposure baking is characterized in that the substrate to be processed is placed in an environment in which an electric field that is parallel to the surface of the substrate and whose direction changes relatively with time exists.

  Another embodiment of the present invention is a baking apparatus for baking a substrate to be processed in which a desired pattern is exposed on a chemically amplified resist film, the substrate to be processed being placed on the substrate. A bake plate to be heat-treated, a first electrode pair disposed on the bake plate with the substrate sandwiched therebetween, and a first electrode pair disposed on the bake plate with the substrate sandwiched therebetween. An AC voltage is applied to each of the second electrode pair and the first and second electrode pairs arranged orthogonally to each other, and an electric field that is parallel to the substrate and whose direction changes relatively with time is applied. And means.

  Another embodiment of the present invention is a baking apparatus for baking a substrate to be processed in which a desired pattern is exposed on a chemically amplified resist film, the substrate to be processed being placed on the substrate. Centering on a bake plate to be heat-treated, a pair of electrodes opposed to each other with the substrate sandwiched on the bake plate, means for applying a DC voltage between the electrodes, and an axis orthogonal to the surface of the substrate Means for rotating the substrate or the electrode.

  According to the present invention, in a pattern forming method of forming a resist pattern by applying a resist with a desired film thickness on a substrate to be processed, and baking after application, exposure, baking after exposure, development, rinsing, and drying. When the post-exposure baking is performed, the substrate to be processed is placed in an environment where there is an electric field parallel to the substrate surface and the direction of which relatively changes with time, whereby the line edge roughness of the resist pattern to be formed can be reduced. In this case, unlike the reflow baking method, the pattern dimension does not change.

  Before describing the embodiment of the present invention, the reason why line edge roughness occurs when conventional pattern formation is performed will be described with reference to FIG. 6A shows the distribution of acid generated by exposure, FIG. 6B shows how the acid moves by post-exposure baking, and FIG. 6C shows the edge formed by development.

  In a state where a chemically amplified resist is applied on a substrate to be processed such as a semiconductor wafer and baking and exposure are performed after application, as shown in FIG. 6A, the acid generated by exposure remains in the exposed portion. Yes. However, in the post-exposure baking process, as shown in FIG. 6B, due to the difference in potential energy in the resist film, the diffusion of the acid generated by the exposure is biased, and a part of the acid jumps out to the unexposed part. End up. Due to this bias of acid, line edge roughness occurs after development, as shown in FIG.

  In the present embodiment, acid bias during the post-exposure baking is prevented. The details of the present invention will be described below with reference to the illustrated embodiments.

(First embodiment)
First, as shown in FIG. 1, a chemically amplified resist 12 is applied on a substrate 11 such as a semiconductor wafer by spin coating, and then the resist is baked (post application baking). Here, as the chemically amplified resist 12, for example, M60G manufactured by JSR Corporation can be used.

  Next, as shown in FIG. 2, a mask 20 having an L / S (line and space) pattern, for example, having a light shielding film 22 formed on a part of the transparent substrate 21, is used to remove the resist 12 with ultraviolet rays, electron beams, or X Expose with lines. By this exposure, the exposed portion 12 a and the unexposed portion 12 b exist in the resist 12. The arrangement of the acid in the exposed portion 12a and the unexposed portion 12b at this time is as shown in FIG. 6 (a).

  Next, the substrate 11 to be processed is installed in the baking apparatus shown in FIG. 3, and post-exposure baking is performed. In the baking apparatus of FIG. 3, first electrodes 32 a and 32 b are arranged on a hot plate (bake plate) 31 on which the substrate 11 to be processed is placed so as to face each other with the substrate 11 to be processed therebetween. The second electrodes 33a and 33b are arranged so as to be orthogonal to the electrodes 32a and 32b. Then, a first AC electric field is applied between the electrodes 32a and 32b by the AC power supply 34, and an AC electric field shifted by a quarter cycle from the first AC electric field is applied between the electrodes 33a and 33b by the AC power supply 35. It is like that.

  Note that the voltage of the AC power supplies 34 and 35 only needs to be strong enough to apply a sufficient electric field to the surface of the substrate 11 to be processed, and may be 5 kV for an 8-inch wafer, for example. Further, the magnitude of the voltage in the x direction and the y direction may be changed according to the pattern on the substrate 11 to be processed. For example, when there are many line patterns along the y direction and the edge roughness is further reduced, the voltage of the power source 35 in the y direction may be made larger than the power source 34 in the x direction.

  As described above, by applying the electric field to the electrodes 32a, 32b and 33a, 33b of the baking apparatus, a rotating electric field is applied to the surface of the substrate 11 to be processed. For this reason, the direction of movement of the acid that is about to move during baking is regulated by the electric field and does not protrude significantly into the unexposed area.

  After the post-exposure baking process, development, rinsing and drying processes are performed. The line edge roughness of the resist pattern thus obtained was greatly reduced because the movement of the acid was restricted by the rotating electric field described above.

  As described above, according to the present embodiment, when the post-exposure baking is performed, the substrate 11 to be processed is placed in an environment that is parallel to the surface of the substrate 11 and in which an electric field that rotates is present. . For this reason, line edge roughness can be reduced without causing a change in pattern dimension.

(Second Embodiment)
4 and 5 are diagrams for explaining the schematic configuration of a baking apparatus according to the second embodiment of the present invention. FIG. 4 is a plan view and FIG. 5 is a cross-sectional view. In addition, the same code | symbol is attached | subjected to FIG. 3 and an identical part, and the detailed description is abbreviate | omitted.

  The present embodiment is different from the previous embodiment in that instead of applying an AC electric field, a DC electric field is applied and the substrate is rotated instead of rotating the electric field.

  Electrodes 42 a and 42 b are disposed on a hot plate (bake plate) 31 on which the substrate 11 to be processed is placed so as to face each other with the substrate 11 to be processed interposed therebetween. An electric field is applied between the electrodes 42a and 42b by a DC power supply 44 in a direction parallel to the substrate surface. The bake plate 31 is rotated by a rotation mechanism 47. Here, by aligning the center of the substrate to be processed 11 with the center of the baking plate 31, the substrate to be processed 11 rotates about the center of the substrate surface. In the figure, reference numeral 48 denotes a pin for setting the substrate 11 to be processed on the baking plate 31.

  As in the previous embodiment, as shown in FIGS. 1 and 2, a chemically amplified resist 12 is applied on the substrate 11 to be processed, and after the application, the resist 12 is formed using a mask 20. Exposed.

  Next, the to-be-processed substrate 11 was installed in the baking apparatus shown in FIGS. 4 and 5, and post-exposure baking was performed. At this time, since a DC electric field is applied in parallel to the surface of the substrate 11 to be processed and the substrate 11 to be processed is rotating, this is equivalent to applying a rotating electric field to the surface of the substrate 11 to be processed. . Therefore, as in the previous embodiment, the direction of movement of the acid that is about to move during baking is restricted by the electric field and does not protrude significantly into the unexposed area.

  As described above, according to the present embodiment, the substrate to be processed 11 is placed in an environment in which a DC electric field parallel to the surface of the substrate 11 is present during post-exposure baking, and the substrate 12 is rotated to rotate the resist 12. It is possible to suppress the movement of the acid therein. For this reason, the effect similar to 1st Embodiment is acquired.

(Modification)
In addition, this invention is not limited to each embodiment mentioned above. In the embodiment, M60G manufactured by JSR Corporation was used as the resist. However, the resist is not limited thereto, and a chemically amplified resist that generates an acid upon exposure can be used. In the second embodiment, the bake plate on which the substrate to be processed is placed is rotated. Alternatively, the electrodes 42a and 42b may be rotated around the center of the substrate 11 to be processed. .

  In addition, various modifications can be made without departing from the scope of the present invention.

Sectional drawing which shows the state which apply | coated the resist on the to-be-processed substrate. Sectional drawing which shows the state which exposed the pattern of the mask to the resist. The top view which shows schematic structure of the baking apparatus used for 1st Embodiment. The top view which shows schematic structure of the baking apparatus used for 2nd Embodiment. Sectional drawing which shows schematic structure of the baking apparatus used for 2nd Embodiment. The schematic diagram for demonstrating the reason that line edge roughness generate | occur | produces by the movement of the acid at the time of baking after exposure.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 ... To-be-processed substrate 12 ... Resist 12a ... Exposure part 12b ... Unexposed part 20 ... Mask 21 ... Transparent substrate 22 ... Light-shielding film 31 ... Hot plate (baking board)
32a, 32b ... first electrode 33a, 33b ... second electrode 34, 35 ... AC power source 42a, 42b ... electrode 44 ... DC power source 47 ... rotating mechanism 48 ... pin

Claims (5)

A method of forming a resist pattern by applying a chemically amplified resist on a substrate to be processed and performing baking, exposure, post-exposure baking, development, rinsing, and drying after coating,
A resist pattern forming method, wherein the substrate to be processed is placed in an environment in which an electric field whose direction changes relatively with time is present parallel to the surface of the substrate during post-exposure baking.   By placing the substrate to be processed during the post-exposure baking in an environment that generates two sets of electric fields that are orthogonal to each other and parallel to the surface of the substrate, and by changing the strength of the two sets of electric fields over time, 2. The method of forming a resist pattern according to claim 1, wherein the total electric field strength and direction are changed.   The substrate or the electric field is rotated about an axis orthogonal to the surface of the substrate by placing the substrate to be processed in an environment that generates an electric field parallel to the surface of the substrate during the post-exposure baking. Item 2. A resist pattern forming method according to Item 1. A baking apparatus for baking a substrate to be processed having a desired pattern exposed to a chemically amplified resist film,
A bake plate on which the substrate to be processed is placed and heat-treats the substrate;
On the bake plate, a first electrode pair disposed opposite to the substrate,
A second electrode pair disposed on the bake plate so as to face each other with the substrate interposed therebetween, and disposed in a relationship orthogonal to the first electrode pair;
Means for applying an alternating voltage to each of the first and second electrode pairs and applying an electric field that is parallel to the substrate and whose direction changes relatively with time;
The baking apparatus characterized by comprising. A baking apparatus for baking a substrate to be processed having a desired pattern exposed to a chemically amplified resist film,
A bake plate on which the substrate to be processed is placed and heat-treats the substrate;
On the bake plate, a pair of electrodes arranged opposite to each other with the substrate interposed therebetween,
Means for applying a DC voltage between the electrodes;
Means for rotating the substrate or the electrode about an axis orthogonal to the surface of the substrate;
The baking apparatus characterized by comprising.

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