JP3256571B2 - Method of forming three-dimensional structure - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technique for forming a desired pattern on a sensitive material such as a resist, and more particularly, to exposing a sensitive material to a three-dimensional structure or directly subjecting a sample to a three-dimensional pattern.
The present invention relates to a method for forming a three-dimensional structure for forming a pattern .

[0002]

2. Description of the Related Art Conventionally, as one of the key techniques in forming a semiconductor integrated circuit, an exposure transfer technique of a two-dimensional plane image is known. In this technique, a three-dimensional structure is formed starting from the selective removal of the photoconductor thin film. Specifically, a desired pattern of a two-dimensional plane is exposed and transferred to a resist on the wafer, and the wafer is selectively etched using the formed resist pattern as a mask. This exposure transfer technique is also applied to a selective growth technique of a thin film single crystal, and a selective epitaxial growth is performed. This can also be said to be one of the techniques for forming a three-dimensional structure.

However, these techniques do not form an arbitrary three-dimensional structure designed in advance in one processing process, but are complicated and have a low degree of freedom. That is, to form grooves with different depths on the wafer surface,
It is necessary to alternately repeat formation of a resist pattern by exposure transfer and selective etching of the wafer, which is extremely troublesome.

On the other hand, in recent years, a series of technical developments called micromachine technology has been advanced. This technology is
Essentially, this is an extension of the process technology for producing a semiconductor integrated circuit.
Emphasizes dimensionality. For example, it has been reported that a three-dimensional shape such as a micropump, a micromotor, or a microvalve is formed by repeating an exposure process and an etching process on a silicon wafer. The ultimate forms of these technologies include the arbitrary shape of 3
Although a form in which a dimensional structure is formed by a simpler one-time process is conceivable, it has not been put to practical use yet.

[0005]

As described above, conventionally, the method using the exposure transfer technique of a sensitive material such as a resist,
In order to form a three-dimensional structure on a sample, it is necessary to alternately repeat an exposure process and an etching process, which increases the number of processes and is extremely complicated.

The present invention has been made in view of the above circumstances, and has as its object to form an arbitrary three-dimensional structure with a small number of processes and to provide a functional device including a semiconductor. An object of the present invention is to provide a method for forming a suitable three-dimensional structure.

[0007]

The gist of the present invention is to transfer a three-dimensional pattern directly to a sensitive material such as a resist.

That is, the present invention (Claim 1) provides an external
A variable image mask whose pattern is changed by the drive signal
Three-dimensional structure that forms a three-dimensional pattern on the sample surface by using
A method of forming a body, in which a sample is stored in a container.
Filling the sample material with photosensitive material and irradiating the sample surface with light
Etching to etch harder photosensitive material and sample
Illuminate the variable image mask with the coexisting
To form a pattern on the mask on the etched surface of the sample.
By imaging, a mask pattern is formed on the surface to be etched.
Hardens and precipitates the photosensitive material according to the
The basic process is to suppress the etching reaction
Bring the sample closer to the variable image mask side along the optical axis direction.
As well as variable for each sample movement position
The above basic process is repeated by changing the pattern of the image mask.
It is characterized by returning .

Further, the present invention (Claim 2), in the method for forming a three-dimensional structure which uses an exposure of the sensitive material, sample
Fills the container with the etching material and photosensitive material
The photosensitive material and the sample are cured by light irradiation on the surface of the sample.
With the etching material coexisting
A hologram reproduction image is formed inside the sample, and in this state
While etching the sample with the etching material,
The photosensitive material is cured and deposited on the image forming surface of the reproduced program image.
By suppressing the etching reaction of the sample at the deposition part
And forming a three-dimensional pattern on the sample surface . Here, the following are preferable embodiments of the present invention.

[0010]

(2) A semiconductor wafer is used as a sample, a photosensitive material and an etching material coexist on the surface of the wafer, and the etching reaction is accelerated or suppressed by the excitation light (or a hologram reproduction real image). Forming a three-dimensional structure. (3) A hologram reproduction real image has the same structure periodically repeated, and a plurality of three-dimensional structures are formed in one process.

[0012]

According to the present invention (claim 1), by combining the pattern change of the variable image mask and the movement of the fine movement stage, it is possible to form different patterns at different height positions on the sample. Therefore, by using a semiconductor wafer or the like as a sample, and coexisting an etching material and a photosensitive material on the wafer surface, the wafer can be directly processed into a three-dimensional structure. That is, a three-dimensional structure can be formed by one process of performing etching while exposing, instead of alternately repeating exposure and development (or etching).

According to the present invention, by forming a hologram reconstructed real image inside the sample, it is possible to simultaneously expose different height positions of the sample, thereby allowing a structure having an arbitrary three-dimensional shape to be exposed once. Can be formed by the following exposure process.

Therefore, it is possible to form a three-dimensional structure by a simple process as compared with a conventional method in which an exposure process and an etching process are repeated. In addition, since it is possible to form a three-dimensional structure with a continuous shape change in the depth direction, an unprecedented new semiconductor functional device and various functional elements are similar to conventional semiconductor integrated circuits. It will be created by a simple process.

[0015]

DETAILED DESCRIPTION FIG. 1 is a schematic diagram showing a three-dimensional structure forming apparatus according to a first exemplary embodiment of the present invention. In the figure, reference numeral 11 denotes a variable image mask including a liquid crystal shutter or the like, and this mask 11 is irradiated with excitation light 12 from an excitation light source (not shown). The light transmitted through the mask 11 is reduced and projected on the sample 20 by the reduction projection optical system 13. Sample 20
Is obtained by applying a photoresist 22 on a silicon wafer 21. The sample 20 is fixedly held on a stage 14, and the stage 14 is movable in the optical axis direction by a stage driving mechanism 15. Also, the variable image mask 1
1 and the stage drive mechanism 15 are driven in synchronization by a control circuit 16.

FIG. 1 shows a third embodiment according to the present invention.
It is a schematic structure figure showing a three-dimensional structure formation device. 11 in the figure
Is a variable image mask composed of a liquid crystal shutter or the like. The mask 11 has an excitation light 12 from an excitation light source (not shown).
Is irradiated. The light transmitted through the mask 11 is reduced and projected on the sample 20 by the reduction projection optical system 13. Sample 20
Is obtained by applying a photoresist 22 on a silicon wafer 21. The sample 20 is fixedly held on a stage 14, and the stage 14 is movable in the optical axis direction by a stage driving mechanism 15. Also, the variable image mask 1
1 and the stage drive mechanism 15 are driven in synchronization by a control circuit 16.

In such a configuration, the excitation light wavelength is set to 2
The optical system 13 was designed to use a reduction projection lens of 10: 1 and the focal length was set to 50 mm.
The total power of the excitation light was set to 230 W, and the total area of the imaging surface was 1
00mm ² It was designed to be. The resist material was selected so that the light power density on the image forming surface exceeded the photosensitivity threshold of the photoresist 22, and the resolution in the normal direction of the image was evaluated to be about 0.5 μm. While electrically controlling the pattern of the variable image mask 11 and changing the position of the sample 20 on the stage 14 in the optical axis direction according to the exposure and curing, the resist 22 can be exposed and cured in a three-dimensional shape. did it.

When the energy density on the mask image forming surface is ρ0 and the energy density at a position δ away from the curved surface in the normal direction is ρ, it is possible to discriminate between ρ0 and ρ. What is necessary is just to have a photosensitive reaction which can be performed.

Next, the three-dimensional processing of the resist will be described more specifically. FIG. 2 shows a variable image mask 11.
Is an example using a liquid crystal shutter. The liquid crystal shutter has small pixels arranged in a matrix as shown in FIG. 2A, and is turned on / off (transmitted / shielded) for each pixel by external driving. By using such a mask, for example, FIG.
As shown in (c) and (d), a different arbitrary pattern including the light-transmitting portion 11a and the light-shielding portion 11b can be formed.

First, the liquid crystal shutter is set in the pattern shown in FIG. 2B, and the image forming position is set on the surface of the resist 22 as shown in FIG. 3A. In this case, the surface of the resist 22 is selectively exposed and cured. Subsequently, when the imaging position is moved and the resist 22 is cured to a position deeper than the surface, a cured portion 23 is selectively formed from the surface to a predetermined depth as shown in FIG. 3B. Next, the liquid crystal shutter is set to the pattern shown in FIG. 2C, and the imaging position is moved to a deeper position while the resist 22 is cured.
As shown in FIG. 3C, a hardened portion 23 is formed. Next, the liquid crystal shutter is set in the pattern shown in FIG. 2D, the image forming position is moved, and the hardened portion 23 is formed at a deeper position as shown in FIG. 3D.

As a result, the resist 22 is three-dimensionally exposed. When the resist 22 is developed, a resist pattern having a plurality of steps on the surface is obtained as shown in FIG. In this example, the exposure of the resist is performed in the deep direction from the surface side, but may be performed in order from the deep to the shallow. Further, in this example, there is a portion that remains without being cured inside the resist film. However, if the patterns of FIGS. 5A, 5B, and 5C are sequentially used, a pattern in which the interior is cured can be obtained.

As described above, in this embodiment , the liquid crystal shutter 1
By changing the pattern 1 and moving the stage 14 so that the resist 22 comes to a position where the pattern should be formed, different patterns can be formed at different heights of the resist 22. Therefore, the resist 22 can be three-dimensionally exposed and cured. If a metal or the like is molded on the cured resist pattern and the resist is removed, a structure having a shape as shown in FIG. Can be formed. Further, if this is used as a mold and the metal or resin is molded and then released, a structure made of metal or resin having the same shape as that of FIG. 4A can be formed. If a method for removing the resist and a method for releasing the resist are devised, it is possible to form a structure having a cavity therein, which can be effectively applied to the manufacture of a micro device.

[0023] Figure 6, according to a first embodiment of the present invention 3
It is a schematic structure figure showing a three-dimensional structure formation device. The same parts as those in FIG. 1 are denoted by the same reference numerals, and detailed description thereof will be omitted.

This embodiment differs from the above-described reference example in that the wafer is directly processed instead of forming a resist pattern on the wafer. That is, the silicon wafer 21 is placed in a container 44 as a sample, and the etching material and the photosensitive material 4 are placed in the container 44.
5 are filled. Note that the container 44 is moved in the optical axis direction by the drive mechanism 15.

With such a configuration, the wafer 21 can be processed into a three-dimensional shape by linking the change in the pattern of the variable image mask 11 and the movement of the container 44 in the same manner as in the above-described reference example . In this embodiment, the wafer 21
Is etched from the entire surface, but the light-irradiated (imaged) portion is not etched because the photosensitive material is hardened on the wafer surface. Therefore, similarly to the above-described reference example , if selective exposure is performed in the depth direction from the resist surface side, the wafer 21 can be patterned into the same shape as that of FIG.

Instead of utilizing the suppression of the etching reaction by exposure, it is also possible to utilize the promotion of the etching reaction by exposure. In this case, the container 44 is filled only with an etching material whose etching reaction is accelerated by light excitation. This etching material accelerates an etching reaction by light excitation, and may be a liquid phase type or a gas phase type.

However, in this method, since the etching reaction does not proceed unless the resist surface is at the image forming position, it is necessary to move the stage at a pitch equal to or less than the depth of focus while maintaining the pattern to be etched. . For example, the highest position of the three-dimensional pattern in which the pattern of the liquid crystal shutter is to be formed is masked, and in this state, the container 44 is gradually moved to the light source side, and the wafer 21 is selectively etched to the second highest position. I do. Next, the pattern of the liquid crystal shutter is masked up to the second highest position. In this state, the container 44 is moved to the light source side, and the wafer 21 is selectively etched to the third highest position. By repeating this, a three-dimensional structure can be formed on the wafer 21. Next, a method of forming a three-dimensional structure using a hologram will be described as another embodiment of the present invention.

FIG. 7 is a diagram for explaining a second reference example method of the present invention. In the figure, reference numeral 51 denotes a laser beam incident on the hologram, 52 denotes a hologram, and 53 denotes a hologram reproduced real image light. Reference numeral 60 denotes a sample, which is obtained by applying a photoresist 62 on a silicon wafer 61.

A hologram reproduction real image was formed inside a photoresist 62 having a photosensitive characteristic with respect to the wavelength of the hologram reproduction light. The reproduction wavelength was set to 248.4 nm, a hologram having a diameter of 30 mm was used as an optical system, and the focal length was designed to be 50 mm. The total power of the reproduced real image light from the hologram is set to 230 W, and the total area of the imaging curved surface is 100 m.
m ² The hologram was designed so that The resist material was selected so that the light power density on the image forming surface exceeded the photoresist exposure threshold, and the resolution in the normal direction of the image forming surface was evaluated to be about 0.5 μm. As a result, the resist 62 was exposed and cured in a curved shape.

When the resist 62 is developed,
A curved resist pattern could be formed.
As described above, according to the present embodiment , by using the hologram reproduced image, the resist 22 can be three-dimensionally exposed and cured by one-circuit exposure, and a three-dimensional structure of the resist can be formed.

The hologram may be a hologram produced by a hologram photographing apparatus. However, it is preferable to use a computer generated hologram in order to execute a periodic repetitive structure of the structure and a reduction operation. Further, as the resist, it is possible to distinguish between ρ0 and ρ, where ρ0 is the energy density on the curved surface on which the hologram real image is formed and ρ is the energy density at a position δ away from the curved surface in the normal direction. Any material having a photosensitive reaction may be used.

FIG. 8 is a diagram for explaining the method of the second embodiment of the present invention. The same parts as those in FIG. 7 are denoted by the same reference numerals, and detailed description thereof will be omitted. This embodiment differs from the second embodiment described above in that the wafer is directly processed instead of forming a resist pattern on the wafer. That is, a silicon wafer 61 as a sample is placed in a container 54, and the container 54 is filled with an etching material and a photosensitive material 55.

The image plane of the hologram reproduction real image is set inside the single crystal silicon wafer 61. Further, the silicon wafer 61 was brought into contact with a mixed solution system of an etching material and a photo-curing resist material, and a processing reaction was advanced.
As a result, the erosion reaction of silicon progressed to the image forming surface of the hologram reproduction real image, and when the silicon material reached the image forming surface, the hardening and deposition reaction of the resist material on the silicon processing surface progressed. Thereby, the silicon etching reaction was stopped, and the silicon wafer 61 could be processed into a three-dimensional curved surface shape. The etching material system and its suppression reaction material system may be a liquid phase system or a gas phase system.

The present invention is not limited to the above embodiments. In the embodiment, silicon is used as the substrate material. However, various semiconductor materials can be used in combination with the etching material, and the present invention can be applied to materials other than the semiconductor material. In addition, various modifications can be made without departing from the scope of the present invention.

[0035]

As described above in detail, according to the present invention, an arbitrary three-dimensional structure can be formed by a small number of processes, and a method of forming a three-dimensional structure suitable for manufacturing a functional device including a semiconductor. Can be realized.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing a three-dimensional structure forming apparatus according to a first reference example of the present invention;

FIG. 2 is a plan view showing an example of a variable image mask used in a first reference example ;

FIG. 3 is a schematic diagram for explaining the operation of the first reference example ;

FIG. 4 is a schematic diagram for explaining the operation of the first reference example ;

FIG. 5 is a schematic view showing an example of a pattern of a liquid crystal shutter.

FIG. 6 is a schematic configuration diagram showing a three-dimensional structure forming apparatus according to a first embodiment of the present invention;

FIG. 7 is a schematic diagram for explaining a second reference example method of the present invention;

FIG. 8 is a schematic diagram illustrating a method according to a second embodiment of the present invention.

[Explanation of symbols]

11: Variable image mask, 12: Excitation light, 13: Reduction projection optical system, 14: Stage, 15: Stage drive mechanism, 2
0,60: sample, 21, 61: silicon wafer, 2
2, 62 photoresist, 23 exposure hardened part, 24 ...
Metal, 44, 54: container, 45, 55: etching and photosensitive material, 51: laser incident light, 52: hologram, 5
3. Hologram reproduction real image light.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-61-111528 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G03F 1/00-1/16

Claims (2)

(57) [Claims] 1. A method for forming a three-dimensional structure on a surface of a sample using a variable image mask whose pattern is changed by an external drive signal, wherein the three-dimensional structure is formed in a container containing the sample. Etching materials and photosensitive materials
The variable image mask is irradiated with light to form a pattern of the mask on the surface to be etched of the sample in a state where the photosensitive material which is filled and cured on the surface of the sample by light irradiation and the etching material for etching the sample coexist. by the image, the
The basic process is to harden and deposit a photosensitive material in accordance with the mask pattern on the surface to be etched, and to suppress the etching reaction at the deposited portion. The sample is sequentially moved along the optical axis so as to approach the variable image mask side. A method of forming a three-dimensional structure, wherein the basic process is repeated by changing the pattern of the variable image mask for each moving position of the sample. 2. An etching material in a container containing a sample.
A hologram reproduction image is formed inside the sample in a state where the photosensitive material that cures by light irradiation on the surface of the sample and the etching material that etches the sample coexist. A three-dimensional pattern is formed on the surface of the sample by etching the sample and by hardening and depositing a photosensitive material on the image forming surface of the hologram reproduced image to suppress an etching reaction of the sample at the deposited portion. The method of forming the structure.