JPH02124590A - Method and device for forming hologram - Google Patents

Abstract

PURPOSE:To form the concentrical patterns of a hologram with high drawing accuracy by forming a photoresist film on a substrate at the point of the time when a photoresist soln. spreads sufficiently on the substrate, then exposing the concentrical patterns of the hologram onto the photoresist on the substrate and subjecting the photoresist to an after-exposing processing. CONSTITUTION:The photoresist soln. is dropped to the central part of rotation of the photoresist substrate B by rotating the substrate B and the rotation of the substrate B is stopped at the point of the time when the soln. spreads sufficiently to the peripheral part of the substrate B, then the photoresist film is formed on the substrate B. The substrate B is again rotated and the concentrical patterns of the hologram are exposed to the photoresist on the substrate B by a light projecting means 2 of a laser beam and a moving means 3 for moving this light projecting means 2 in the direction orthogonal with the revolving shaft 13 of the hologram B; thereafter, the photoresist is subjected to the after-exposing processing. The concentrical patterns of the hologram are formed on the photoresist film uniformly with the high drawing accuracy in this way.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention provides a hologram creation method and apparatus for creating a hologram using photoresist for use in an in-line computer-generated hologram interferometer (hereinafter simply referred to as an interferometer). Regarding.

[Conventional technology]

Interferometers are often used to measure aspherical optical surfaces or known shapes with high precision. An in-line interferometer is used to measure the shape of the axially symmetric lens optical surface and the mold surface for press-molding it. In an in-line interferometer, the reference light and test light are arranged coaxially, so the hologram pattern is concentric circles, and if the test light is a spherical wave, it is possible to measure deep shapes considering the pattern pitch of Polo Dallam. Since the optical system is almost the same for the reference light and the test light, it is easy to keep errors caused by the optical system small. Conventionally, holograms used in this in-line interferometer have been created by using a computer to obtain a concentric pattern of the hologram, drawing it with an X-Y plotter, and then taking a photograph of it, or using an electron beam drawing device instead of an X-Y plotter and photography. It was created by exposing photoresist to light.

[Problem to be solved by the invention]

The method using X-Y blocks and photography can cause distortion, comatic aberration, and spherical aberration in the concentric circular pattern of the hologram due to factors such as the accuracy of the XY plotter, the setting accuracy during photography, lighting and exposure conditions, and development processing conditions. etc., and the processing is complicated. In addition, with the method of using an electron beam lithography system, the lithography accuracy is quite high for a narrow lithography range, but when the lithography range is expanded, the leakage magnetic flux of the electromagnetic lens increases and the exposure time becomes longer, so the lithography There is a problem in that positional drift and the like occur, resulting in a decrease in drawing accuracy, and if this problem were to be solved, the apparatus would become larger and more expensive. -For boat fishing, electron beam lithography equipment is originally expensive;
Since the normal drawing range is about 5 mm square, it is not appropriate to use it for creating holograms.

The present invention has been made to solve the above-mentioned problems, and provides a hologram that can easily form a concentric pattern of holograms with uniformly high drawing accuracy regardless of the width or narrowness of the drawing range in photoresist. The present invention provides a method and apparatus for making the same.

[Means to solve the problem]

The present invention rotates a photoresist substrate, drops a photoresist solution onto the center of rotation of the substrate, and when the solution has sufficiently spread to the periphery of the substrate, the rotation of the substrate is stopped and a photoresist solution is placed on the substrate. A resist film is formed, and then the substrate is rotated again to apply a laser beam to the seven resists on the substrate using a laser beam projecting means and a moving means that moves the projecting means in a direction orthogonal to the rotation axis of the substrate. A hologram production method characterized by exposing a concentric pattern of a hologram and then subjecting the photoresist to a post-exposure treatment, and a substrate rotation used in carrying out this method, in which a photoresist substrate is exchangeably fixed and rotated. means for projecting light onto the photoresist on the substrate fixed to the substrate rotation means; moving means for linearly moving the light projection means or the substrate rotation means in a direction orthogonal to the rotation axis of the photoresist substrate; and a control device for controlling the drive of the means to rotate the photoresist substrate by the substrate rotation means, to cause a light beam to be incident on the photoresist on the substrate by the light projecting means, and to further move the incident position of the light beam by the moving means. A hologram creation device is characterized by:

[Effect]

According to the method of the present invention, a photoresist film of a desired thickness can be uniformly formed on a photoresist substrate, and a concentric pattern of a hologram can be uniformly exposed on the photoresist film with high drawing accuracy. Holograms used in interferometers can be easily formed. Further, by using the apparatus of the present invention, it is possible to efficiently perform the exposure of the above-mentioned concentric pattern.

〔Example〕

The present invention will be explained below using illustrated examples.

Fig. 1 is a schematic configuration diagram showing an example of a device used to carry out the hologram production method of the present invention, and Fig. 2 is an adjustment that allows the laser beam to be incident by moving on a straight line passing through the center of rotation of the substrate. FIG. 2 is a principle diagram showing an example of a method for determining a quantity.

In FIG. 1, ■ is a substrate rotating means, 2 is a light projecting means, and 3 is a substrate rotating means.
4 is a moving means, and 4 is a control device. The substrate rotation means 1 is
A precision bearing 11 such as an air bearing, and a bearing 11
It consists of a rotating shaft I3 that is rotatably supported by a rotary shaft I3 and has a substrate mounting base 12 with a vacuum chuck at its upper end, a DC motor 14 that rotates the rotating shaft 13, and the like. The light projecting means 2 is
It consists of a laser light source, an optical system such as an exhang lens, a polarizing plate, a beam splitter/reflection surface, and an imaging lens, and a lens drive mechanism that moves the imaging lens to automatically form an image. A known mechanism used in CD players and the like is used for this lens drive mechanism.

The moving means 3 includes three stages of feed screws for linearly moving the light projecting means 2 parallel to the upper surface of the substrate mount 12 of the substrate rotation means 1, a DC motor 32 for rotating the feed screw 31, and the like. The control device 4 includes a microcombi coater 41, a keyboard 42, a rotation detector 43 and an amplifier 44 for driving and controlling the motor 14 of the substrate rotating means 1, and a rotation detector 45 for driving and controlling the motor 32 of the moving means 3. and an amplifier 46.

To explain the creation of holograms using this device,
First, a glass substrate B is placed on the substrate mount 12 of the substrate rotation means 1 and fixed by a vacuum chuck. Bearing 11
The pipe 15 protruding from the top is a satanyong pipe of a vacuum chuck. Next, board mounting base 1 with board B attached
2 was rotated at 3,000 to 5,000 rpm, and the photoresist solution was dropped onto the center of rotation of the substrate B using an appropriate means such as a ring or a billet, so that the photoresist solution was sufficiently spread to the periphery of the substrate B. At this point, the rotation of the board mounting base 12 is stopped. Thereby 1 to 5
A uniform photoresist I film with a thickness of μm is formed.

Then, while rotating the substrate mount 12 and moving the light projection means 2 by the moving means 3 in a direction perpendicular to the rotation axis of the substrate mount 12, the light projection means 2 projects a concentric pattern of the hologram onto the substrate B. Expose the photoresist. Although this exposure depends on the type of photoresist and laser light source, it can be completed in about one hour, including preparation for normal light. After the exposure is completed, the substrate B having the exposed photoresist is removed from the substrate mounting table 12, and then processed to obtain a hologram in the same manner as in the production of a hologram using a conventional photoresist.

Drive control of the substrate rotation means 1 described above for forming a photoresist film on the substrate B and drive control of the light projection means 2 and the like for exposing a concentric pattern on the photoresist are performed in response to commands from the keyboard 42. The microcomputer 41 performs this. In particular, the drive control for exposing the photoresist to a concentric pattern is such that the microcomputer 41 receives the coefficients of the design function of the test shape from the keyboard 42 and automatically calculates the hologram pattern. The rotation speed and the moving speed of the light projecting means 2,
That is, controlling the rotation speed of the rotating shaft 13 and the feed screw 31,
This is performed by controlling the incidence of a laser beam onto the photoresist by the light projecting means 2.

The rotation of the rotating shaft 13 and the feed screw 31 is determined by amplifiers 44 and 46 which receive the drive signal 4g from the microcomputer 41, and the DC motors 14 and 32 are controlled by rotation detectors 43 and 45, respectively.
This is done by driving to give a predetermined rotation speed based on the detection information of. In addition, the laser beam incident on the photoresist by the light projecting means 2 is attached to the photoresist on the substrate B so as to form an image in a spot of about 1 μm in diameter. By using this, the exposure range can be easily reduced to about 0.05 μm or less. Further, the horizontal movement of the light projection means 2 by the feed screw 31 can be easily achieved with a positioning accuracy of about 0.1 μm in the exposure range by a combination of an air slider and a zarpo motor. Therefore, regardless of the width or narrowness of the drawing range when exposing the concentric pattern by the light projecting means 2, the pattern pitch error is 0.
．． It can be performed with high drawing accuracy of 1 μm or less,
High precision holograms can be obtained. It goes without saying that a bearing with less axial runout or a lateral feeder with high feed accuracy other than an air bearing or a feed screw may be used as the bearing or the lateral feeder. Furthermore, instead of horizontally transporting the light projecting means 2, the substrate rotating means 1 may be horizontally transported.

Incidentally, since the laser beam must be incident on a straight line passing through the rotation center of the substrate, in order to adjust it, in the illustrated example, the bearing 11 of the substrate rotation means 1 is aligned with the direction of the rotation axis 13 and the feed screw 31. The light projecting means 2 can be adjusted and moved in a direction perpendicular to the sending direction of the light projecting means 2. However, the present invention is not limited to this, and the transverse feeding means may be capable of adjustment movement in the same direction.

This adjustment movement may be performed by exposing the dummy resist substrate in advance at the rotation center position and determining the amount of adjustment movement from the result. The specific method will be explained below with reference to FIG. 2 as well.

First, a photoresist substrate is attached to the substrate mounting table 12, and a photoresist film is formed on the substrate according to the procedure of the hologram production method described above to produce a dummy resist substrate. Next, while rotating the dummy resist substrate, light is projected at the P1 position shown in FIG. By means of means 2, a laser beam is made incident on the photoresist film. Furthermore, the laser beam is similarly incident at position P3, which is moved from P2 by a distance d2 that is approximately the same as dl. The dummy resist substrate subjected to the above exposure is subjected to a post-exposure treatment to obtain a development dummy resist substrate 1 having a concentric pattern as shown in FIG. The radius of the concentric circle of this development dummy resist substrate rl+r
2+r3 is measured using a tool microscope or the like. Then, the length of the perpendicular line drawn from the actual rotation center indicated by 0 in FIG. 2 of the dummy resist substrate to the straight line connecting Pl + P2 + P3,
In other words, if the amount of deviation of the laser beam incident position from the actual center of rotation in the linear movement direction is dy, P is the distance between the foot of the above-mentioned perpendicular line is dx, then r・-ζνi...■ r2=f ; 欝■】A ...■ There is a relationship, and dy-±E ama ν ...■ can be found from the formulas ■ and It can be adjusted so that it is performed on a straight line passing through the center.

Note that r3 is used to determine which is rl when r and r2 are close to each other. Also, for dy, two values, positive and negative, can be obtained using formula 0, but the direction of correction can be determined by correcting about 90% of the calculated value of dy and then obtaining dx and dy in the same way using a dummy resist substrate. Because you can know if you were right or wrong,
Now you can correct it in the right direction. dx, dy
It can be done without error in about 10 minutes by calculating and correcting dx and dy two to three times to make it 1 μm or less. This is an extremely practical method. If this exposure routine is programmed into a microcomputer and executed, work efficiency can be greatly improved. Further, in the above example, the process starts with the creation of a dummy resist substrate, but it is also possible to create a dummy resist substrate separately and attach it to a substrate mounting base.

In addition, in boat fishing, even if the moving straight line of the laser beam deviates from the center of rotation by about ±10 μm, there is often no actual damage.

〔Effect of the invention〕

According to the present invention, a concentric circle pattern of a photoresist hologram is exposed with high drawing accuracy regardless of the width of the drawing range, and a highly accurate hologram used in an in-line interferometer can be created with high productivity. I can do it.

[Brief explanation of drawings]

Figure 1 is a schematic configuration diagram showing an example of a device used to carry out the hologram production method of the present invention, and Figure 2 is an adjustment that allows the laser beam to be incident by moving on a straight line passing through the center of rotation of the substrate. FIG. 2 is a principle diagram showing an example of a method for determining a quantity. l... Board rotation means 11... Bearing 12...
Board mounting base 13... Rotating shaft 14... DC motor 15... Suction pipe 2... Light projecting means 3... Moving means 31... Feed screw
32...DC motor 4...Control device...Microcomputer

Claims (2)

[Claims] (1) Rotate the photoresist substrate and drop the photoresist solution onto the center of rotation of the substrate, and when the solution has sufficiently spread to the periphery of the substrate, stop the rotation of the substrate and apply the photoresist solution onto the substrate. A film is formed, and then the substrate is rotated again to form a concentric circle of a hologram on the photoresist on the substrate using a laser beam projection means and a moving means for moving the projection means in a direction orthogonal to the rotation axis of the substrate. A method for producing a hologram, which comprises performing post-exposure treatment on the photoresist after exposing the pattern. (2) a substrate rotating means for fixing and rotating a photoresist substrate in a replaceable manner; a light projecting means for projecting a light beam from a laser light source onto the photoresist on the substrate fixed to the substrate rotating means; and a light projecting means or a moving means for linearly moving the substrate rotating means in a direction orthogonal to the rotation axis of the photoresist substrate; and a moving means for linearly moving the substrate rotating means in a direction perpendicular to the rotation axis of the photoresist substrate; 1. A hologram creation apparatus comprising: a control device for inputting a light beam using an optical means and further moving the incident position of the light beam using a moving means.