JPH103002A - Method for manufacturing blaze diffraction optical element, and device therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the diffraction efficiency by arranging resist tilted to the optical axis of exposure light and making the stepped surface of a blazed resist pattern vertical to a substrate surface. SOLUTION: When a substrate 3 is mounted on a translation stage 5, the translation stage 5 is tilted to the optical axis of an exposing laser beam EL. Namely, the translation stage 5 is arranged with a tilt angle α to X-axis around Y-axis. And then, the translation stage 5 is translated by controlling a driving part 6 by a main control device 7 so that a converging point of the exposing laser beam EL is positioned at a plotting start position of the resist pattern, namely, the scanning start position of the converging point FP of the exposing laser beam EL. Next, a shutter, which is located in a light path of the exposing laser beam EL, is opened. After that, the main control device 7 controls an intensity modulator 1 and the driving part 6 so that an exposure distribution is formed by which the blazed resist pattern is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a blazed diffractive optical element having a blazed resist pattern (resist pattern having a sawtooth cross section) formed on a substrate, and more particularly to a method and an apparatus for manufacturing a blazed diffractive optical element. It is.

[0002]

2. Description of the Related Art Conventionally, in the production of a diffraction grating, a resist is applied to a substrate, a focused laser beam is scanned on the resist to draw a desired pattern, and a resist pattern of a diffraction grating shape is developed by development. Has been used on a substrate. In order to manufacture a blazed diffractive optical element by forming a blazed resist pattern on a substrate by applying the above method, a resist having a small γ value (inclination indicating a change in the depth to which the resist can be etched with respect to a change in exposure amount) is used. Using the linear exposure characteristic, the exposure amount is controlled in accordance with the depth (height) of the resist pattern, that is, the laser beam is scanned on the resist while controlling the intensity of the laser beam. Later, a method of developing the resist is performed.

[0003]

However, in the above-mentioned conventional method for manufacturing a blazed diffractive optical element, the step surface of the blazed resist pattern is perpendicular to the surface of the substrate due to the diffraction spread of the focused laser beam. It does not become, it leans. As a result, there is a problem that the diffraction efficiency of the order used decreases. The present invention has been made in view of such circumstances, and a problem thereof is to provide a method of manufacturing a blazed diffractive optical element in which a step surface of a blazed resist pattern is perpendicular to a surface of a substrate to improve diffraction efficiency, and It is to provide a device.

[0004]

According to a first aspect of the present invention, a resist is applied to a surface of a substrate, exposure light is collected and irradiated onto the resist, and the intensity of the exposure light is reduced. A method of manufacturing a blaze diffractive optical element for exposing a resist by relatively moving a focal point of exposure light and a resist while controlling, wherein the resist is arranged to be inclined with respect to an optical axis of the exposure light. This is a method for manufacturing a blaze diffractive optical element. According to a fourth aspect of the present invention, there is provided a light source for emitting exposure light, a light-condensing member for condensing exposure light on a resist applied to the surface of the substrate, and a translation on which the substrate is mounted and movable in at least one direction. A blaze diffractive optical element comprising a stage and a control unit for controlling the intensity of the exposure light and the movement of the translation stage, and relatively moving the focus point of the exposure light and the resist while controlling the intensity of the exposure light. A manufacturing apparatus for a blaze diffraction optical element, wherein a translation stage is arranged to be inclined with respect to an optical axis of exposure light.

[0005] With these configurations, since the exposure light is applied to the resist from an oblique direction, the step surface of the blazed resist pattern can be made perpendicular to the surface of the substrate. The optimum tilt angle of the resist or the stage with respect to the optical axis of the exposure light is experimentally determined.

According to a second aspect of the present invention, in the first aspect, a negative resist is used as the resist, a material transparent to exposure light is used as the substrate, and the negative resist is applied to the substrate. A method of manufacturing a blaze diffractive optical element, comprising: exposing exposure light to the substrate from the back side opposite to the front side. With this configuration, a blazed resist pattern can be formed on a substrate even when a negative resist is used.

According to a third aspect of the present invention, in the second aspect of the invention, a wedge-shaped member made of substantially the same material as the substrate or having a refractive index substantially the same as that of the substrate and transparent to exposure light is provided on the back surface of the substrate. A method for manufacturing a blaze diffractive optical element, comprising: bringing a wedge-shaped member into close contact with the wedge-shaped member; and allowing exposure light to be perpendicularly incident on the wedge-shaped member. With this configuration, the condensed exposure light is perpendicularly incident on the wedge-shaped member,
It is possible to prevent deterioration of the light-collecting characteristic of the exposure light. In addition, the exposure light is transmitted through the wedge-shaped member and the substrate and is applied to the resist, but since the difference in the refractive index between the substrate and the resist is small,
The deflection of the exposure light at the interface between the substrate and the resist is small. Therefore, the inclination angle of the exposure light with respect to the resist, that is, the inclination angle of the substrate with respect to the exposure light, can be small.

According to a fifth aspect of the present invention, in accordance with the fourth aspect of the present invention, there is provided a rotatable rotary stage disposed on a translation stage, wherein a substrate is mounted on the rotary stage and rotation of the rotary stage is controlled. A blaze diffractive optical element manufacturing apparatus controlled by means. With this configuration, the concentric blazed resist pattern is formed by moving the translation stage so that the focal point of the exposure light coincides with the rotation center of the rotation stage, and then rotating the rotation stage while moving the translation stage. Can be formed on a substrate.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a schematic configuration of an apparatus for manufacturing a blazed diffractive optical element according to a first embodiment of the present invention. This manufacturing apparatus includes a laser light source L, an intensity modulator 1,
It includes a condenser lens 2, a translation stage 5, a drive unit 6, and a main controller 7. The substrate 3 is placed on the upper surface of the translation stage 5. A positive resist having a small γ value and good linearity is applied to the surface 3a of the substrate 3 to form a resist layer RL (see FIG. 2).

The laser light source L emits a laser beam such as a HeCd laser having a wavelength sensitive to the resist layer RL. A spatial filter (not shown) for selecting an exposure laser beam (exposure light) EL having a favorable wavefront from the laser beam is provided. The intensity modulator 1 modulates the intensity of the exposure laser beam EL using, for example, an acousto-optic effect, and is controlled by a control signal from the main controller 7. The condenser lens 2 is a condenser point FP of the exposure laser beam EL whose intensity has been modulated by the intensity modulator 1.
Is focused on the surface of the resist layer RL.

The translation stage 5 is driven by a drive unit 6 and forms X ′ around the Y axis at a predetermined angle α with respect to the X axis.
It is arranged horizontally so as to move two-dimensionally in the axis and Y-axis directions. Each position of the translation stage 5 in the X′-axis and Y-axis directions is detected by a laser interferometer (not shown) with a resolution of, for example, about 0.02 μm. Further, the translation stage 5 is configured to be finely movable also in the Z-axis direction. The position of the translation stage 5 in the Z-axis direction is controlled by an autofocus mechanism (not shown) so that the focal point FP of the exposure laser beam EL is located on the surface of the resist layer RL.

Next, an example of a method for manufacturing a blaze diffractive optical element using the apparatus for manufacturing a blaze diffractive optical element according to the first embodiment will be described with reference to FIGS. The blaze diffractive optical element 10 manufactured by this manufacturing method is the fourth type.
A blazed resist pattern RP having a saw-toothed cross section as shown in the figure is formed on a substrate 3. In the figure, reference symbol RPa denotes a resist pattern RP
3 shows a stepped surface of FIG.

(1) First, a positive resist having a low γ value and good linearity is applied to the surface 3a of the substrate 3 to form a resist layer R
L is formed. (2) Next, the substrate 3 is placed on the translation stage 5. At this time, the translation stage 5 is moved, as shown in FIGS.
It is inclined with respect to the optical axis of the exposure laser beam EL. That is, the translation stage 5 is inclined around the Y axis by the angle α with respect to the X axis. (3) Next, the main controller 7 controls the drive unit 6 so that the focal point FP of the exposure laser beam EL is located at the drawing surface start position of the resist pattern RP, that is, the scanning start position of the exposure laser beam EL. Then, the translation stage 5 is moved. (4) Next, a shutter (not shown) arranged in the optical path of the exposure laser beam EL is opened. (5) Thereafter, the main controller 7 controls the intensity modulator 1 and the driving unit 6 so that the exposure amount distribution is such that a blazed resist pattern RP as shown in FIG. 4 is obtained.
That is, the translation unit 5 is moved in the X′-axis and Y-axis directions by the drive unit 6 while modulating the intensity of the exposure laser beam EL by the intensity modulator 1. Thereby, the condenser lens 2
The resist layer RL is scanned by the laser beam EL while the exposure laser beam EL condensed by the laser beam EL is inclined and applied to the resist layer RL, and the exposure amount of the exposure laser beam EL is controlled. (6) After this scanning, when the resist layer RL is developed, a blazed resist pattern RP as shown in FIG.
And the blazed diffractive optical element 10 shown in FIG.

Next, the control of the exposure performed by the main controller 7 will be described with reference to FIGS. In order to form a resist pattern having a sawtooth cross section as shown by a dotted line on the resist layer RL of FIG. 2, each point on the X′-axis, that is, each point on the resist layer RL is approximately the length of the arrow. It is necessary to give a proportional illuminance distribution. Here, the direction of the arrow indicates the traveling direction of the refracted light on the surface of the resist layer RL. When the illuminance distribution is rewritten with respect to the X axis, the distribution becomes as shown in FIG. This illuminance distribution changes depending on the inclination angle α of the translation stage 5, but the illuminance distribution can be realized with a condensed beam having a finite spot size by appropriate inclination angle α and intensity modulation of the exposure laser beam EL. The tilt angle α and the exposure laser beam EL
The test exposure is performed while changing the angle α and the illuminance distribution, and the best angle α and the illuminance distribution are experimentally determined.

According to the apparatus for manufacturing a blazed diffractive optical element according to the first embodiment and the method for manufacturing a blazed diffractive optical element using the apparatus, the exposure laser beam EL is applied to the resist layer RL from an oblique direction. Figure 4
Each step surface RPa of the blazed resist pattern RP as shown in FIG. 7 can be made substantially perpendicular to the surface 3a of the substrate 3. Therefore, the diffraction efficiency of the order used can be improved.

Next, an apparatus for manufacturing a blaze diffractive optical element according to a second embodiment of the present invention will be described with reference to FIG. In this embodiment, X ′ is added to the translation stage 5 of the first embodiment.
The rotary stage 4 that can rotate in a plane including the axis and the Y axis is mounted. The rotary stage 4 is driven by a drive unit 6 controlled by a main controller 7, similarly to the translation stage 5.

Next, an example of a method for manufacturing a blaze diffractive optical element using the apparatus for manufacturing a blaze diffractive optical element according to the second embodiment will be described with reference to FIGS. The blaze diffractive optical element 10 'produced by this method is shown in FIG.
A concentric blazed resist pattern RP as shown in FIG.

(1) First, a positive resist having a low γ value and good linearity is applied to the surface 3a of the substrate 3 to form a resist layer R
L is formed. (2) Next, the substrate 3 is placed on the rotary stage 4. At this time, the translation stage 5 is inclined with respect to the optical axis of the exposure laser beam EL as shown in FIG. That is,
The translation stage 5 is tilted around the Y axis by an angle α with respect to the X axis. (3) Next, the main controller 7 controls the drive unit 6 to move the translation stage 5 so that the focal point FP of the exposure laser beam EL is located at the rotation center of the rotation stage 4.
The center of rotation of the rotary stage 4 is the center of the resist pattern RP of the diffractive optical element 10 'shown in FIG. (4) Next, a shutter (not shown) arranged in the optical path of the exposure laser beam EL is opened. (5) Thereafter, the main controller 7 controls the intensity modulator 1 and the driving unit 6 so that the exposure amount distribution is such that a concentric blazed resist pattern RP as shown in FIG. 6 is obtained. That is, while the intensity of the exposure laser beam EL is modulated by the intensity modulator 1, the translation unit 5 is moved in the X′-axis direction by the drive unit 6 and the rotary stage 4 is rotated. At this time, the translation stage 5 is moved in the X′-axis direction such that the focal point FP of the exposure laser beam EL is directed from the center of the resist pattern RP to the outer periphery.
As a result, the exposure laser beam EL condensed by the condenser lens 2 is irradiated onto the resist layer RL at an angle, and the resist layer RL is scanned by the laser beam EL while controlling the exposure amount of the exposure laser beam EL. You. (6) After this scanning, when the resist layer RL is developed, a concentric blazed resist pattern as shown in FIG. 6 is formed on the surface 3a of the substrate 3, and the blazed diffraction optical element 1
0 'is completed.

In the above embodiments, the case where a positive resist is used has been described. Next, the case where a negative resist is used will be described. First, as a third embodiment, a method of manufacturing a blazed diffractive optical element using a negative resist will be described. In this manufacturing method, a substrate 3 shown in FIGS. 2 and 6 that is transparent to the exposure wavelength (wavelength of the exposure laser beam EL) is used, and is opposite to the surface 3a of the substrate 3 coated with the negative resist. Back 3b of
The exposure laser beam EL is incident from the side and the substrate 3
Is tilted with respect to the exposure laser beam EL as in the above embodiment. According to this embodiment, the blazed diffractive optical element as shown in FIG. 4 can be produced by using the translation stage 5 as shown in FIG. 1, and the translation stage 5 and the rotary stage 4 as shown in FIG. By using the above, a blaze diffractive optical element as shown in FIG. 6 can be produced.

Next, as a fourth embodiment, another method of manufacturing a blaze diffractive optical element using a negative resist will be described. In this manufacturing method, as shown in FIG. 7, a wedge-shaped member 8 made of the same material as the substrate 3 or a transparent wedge-shaped member 8 having substantially the same refractive index as the substrate 3 is adhered to the back surface 3b of the substrate 3 by bonding. In addition, the exposure laser beam EL is vertically incident on the wedge-shaped member 8. According to this embodiment, a blazed diffractive optical element as shown in FIG. 4 can be produced by using the translation stage 5 as shown in FIG.

Next, as a fifth embodiment, another method of manufacturing a concentric blazed diffractive optical element as shown in FIG. 6 using a negative resist will be described. In this manufacturing method, as shown in FIG. 8, a conical wedge-shaped member 8 'made of the same material as the substrate 3 is provided on the back surface 3b of the substrate 3, or a transparent conical wedge having a refractive index substantially equal to that of the substrate 3. The shape member 8 ′ is brought into close contact by bonding, and the exposure laser beam EL is vertically incident on the wedge shape member 8 ′. Also in this embodiment, a blaze diffractive optical element as shown in FIG. 6 can be manufactured by using the translation stage 5 and the rotary stage 4 as shown in FIG.

Further, according to the fourth and fifth embodiments, since the exposure laser beam EL is perpendicularly incident on the wedge-shaped member 8 or 8 ', it is possible to prevent the deterioration of the light-collecting characteristics of the laser beam EL. it can. Further, as shown by arrows in FIGS. 7 and 8, the laser beam EL has a wedge-shaped member 8 or 8 ′,
And the resist is obliquely transmitted through the substrate 3,
Since the difference in the refractive index between the substrate 3 and the negative resist layer RL is small,
The deflection of the laser beam EL at the interface between the substrate 3 and the resist layer RL is small. Therefore, the inclination angle α of the exposure laser beam EL with respect to the negative resist layer RL, that is, the inclination angle α of the substrate 3 with respect to the laser beam EL can be small.

In the first embodiment, the laser beam E for exposure is used without moving the translation stage 5 two-dimensionally.
By moving L two-dimensionally with a scanner or the like,
Alternatively, by moving both the translation stage 5 and the exposure laser beam EL two-dimensionally, the focal point FP of the exposure laser beam EL and the resist layer RL may be relatively moved. . Similarly, in the second embodiment, the exposure laser beam EL may be moved in the X′-axis direction by a scanner or the like without moving the translation stage 5 in the X′-axis direction.

[0024]

According to the method for manufacturing a blazed diffractive optical element according to the first aspect of the present invention and the apparatus for manufacturing a blazed diffractive optical element according to the fourth aspect of the present invention, the step surface of the blazed resist pattern is formed on the substrate. The diffraction efficiency can be improved by being perpendicular to the surface. According to the method for manufacturing a blaze diffractive optical element according to the second aspect of the present invention,
Even when a negative resist is used, a blazed resist pattern can be formed on a substrate. According to the method for manufacturing a blaze diffractive optical element according to the third aspect of the present invention, it is possible to prevent the exposure light from deteriorating and to reduce the inclination angle of the substrate with respect to the exposure light. According to the apparatus for manufacturing a blaze diffractive optical element according to the fifth aspect of the invention, a concentric blazed resist pattern can be formed on a substrate.

[Brief description of the drawings]

FIG. 1 is a diagram showing a schematic configuration of an apparatus for manufacturing a blazed diffractive optical element according to a first embodiment of the present invention.

FIG. 2 is an explanatory view showing a method of manufacturing a blazed diffractive optical element using the manufacturing apparatus of the first embodiment.

FIG. 3 is a diagram showing an illuminance distribution received by a resist;

FIG. 4 is a diagram schematically showing a blazed resist pattern;

FIG. 5 is a view showing a schematic configuration of an apparatus for manufacturing a blazed diffractive optical element according to a second embodiment of the present invention.

FIG. 6 schematically shows a concentric blazed resist pattern.

FIG. 7 is a view showing a method of manufacturing a blaze diffractive optical element according to a fourth embodiment of the present invention.

FIG. 8 is a diagram showing a method of manufacturing a blazed diffractive optical element according to a fifth embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Intensity modulator (control means) 2 ... Condensing lens (condensing member) 3 ... Substrate 3a ... Surface 4 ... Rotating stage 5 ... Translation stage 6 ... Driver 7 ... Main controller (control means) 8,8 ' ... Wedge-shaped members 10, 10 '... Blaze diffractive optical elements L ... Laser light source (light source) EL ... Exposure laser beam (exposure light) RL ... Resist layer (resist) RP ... Resist pattern

Claims (5)

[Claims] 1. A resist is applied to the surface of a substrate, exposure light is focused and irradiated onto the resist, and the focus of the exposure light and the resist are relatively controlled while controlling the intensity of the exposure light. A blaze diffractive optical element for exposing a resist by moving the resist, wherein the resist is arranged to be inclined with respect to the optical axis of the exposure light. 2. A negative resist is used as said resist,
The substrate is made of a material transparent to the exposure light, and the exposure light is incident on the substrate from the back side opposite to the front side of the substrate coated with the negative resist. The method for manufacturing a blaze diffractive optical element according to claim 1. 3. A wedge-shaped member of substantially the same material as the substrate or a wedge-shaped member having a refractive index substantially the same as that of the substrate and transparent to the exposure light, 3. The method for manufacturing a blaze diffractive optical element according to claim 2, wherein the exposure light is made to vertically enter the wedge-shaped member. 4. A light source for emitting exposure light, a condensing member for condensing the exposure light on a resist applied on the surface of the substrate,
A translation stage on which the substrate is mounted, the translation stage being movable in at least one direction, and control means for controlling the intensity of the exposure light and the movement of the translation stage, and the exposure light is controlled while controlling the intensity of the exposure light. A blaze diffractive optical element manufacturing apparatus for relatively moving the light-converging point and the resist, wherein the translation stage is arranged to be inclined with respect to the optical axis of the exposure light. Manufacturing equipment. 5. The apparatus according to claim 1, further comprising a rotatable rotary stage disposed on said translation stage, wherein said substrate is mounted on said rotary stage, and rotation of said rotary stage is controlled by said control means. An apparatus for manufacturing a blaze diffractive optical element according to claim 4.