JPH11162833A - Method of edge exposure for substrate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain desired exposure regardless of the edge shape of a wafer, by measuring coordinate values of a peripheral section of a substrate by means of an external size detector, calculating center coordinate values of the substrate based on the coordinate values of the peripheral section, and then, exposing an area to be exposed at a prescribed distance from the center coordinate values of the substrate in the radial direction. SOLUTION: An exposure light projecting section 4 is moved toward the center of rotation Ct of a turntable 2 until a photosensor detects exposed light in accordance with a command from a controller 7. While the section 4 is moved, the positional coordinates and intensity of the exposed light are measured and stored in the controller 7. Here, a shutter is once closed and the section 4 is moved to the position calculated based on the shape data of a desired peripheral area to be exposed, the eccentricity of a wafer 1, and the positional coordinated data of notches and the exposed light pre-inputted to the controller 7. After the section 4 is moved to the position, the shutter is again opened. Then, while the turntable 2 is rotated, the section 4 is tracked in accordance with the angle of rotation of the turntable 2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a substrate peripheral exposure method for removing unnecessary resist from a peripheral portion of a substrate on which a circuit pattern such as a semiconductor element or a liquid crystal display element is exposed.

[0002]

2. Description of the Related Art Conventionally, in an exposure apparatus used for manufacturing a semiconductor element or the like, a circuit pattern formed on a projection original such as a reticle or a mask is illuminated by an illumination optical system, and this pattern is projected by the projection optical system. 2. Description of the Related Art Image transfer is performed on a photosensitive substrate (generally referred to as a wafer in this specification) such as a glass plate or a wafer coated with a photosensitive agent such as a resist. The wafer is placed on the exposure apparatus by carrying the wafer to the wafer stage while holding the peripheral edge of the wafer by using the transfer arm. When the leading end of the transfer arm holds the peripheral edge of the wafer, the wafer is loaded. There is a case where a part of the photosensitive agent applied thereon is peeled off. In some cases, the stripped photosensitive agent scatters around the wafer, causing dust and the like. Therefore, it is necessary to remove in advance the unnecessary resist applied to the peripheral portion of the wafer from the photosensitive agent applied to the wafer.

As a method of removing such unnecessary resist, the following method is known. Here, a conventional substrate peripheral exposure apparatus is shown in FIG. The wafer 1 has a table driving system 3
The wafer 1 is placed on the rotating table 2 which is rotated in such a manner that the center of the wafer 1 substantially coincides with the rotating center of the rotating table 2. An exposure light irradiator 4 for exposing the peripheral portion of the wafer 1 placed on the turntable 2 is disposed near the turntable 2 in the lateral direction. Further, a wafer end face detection sensor 11 is integrally arranged in the exposure light irradiation section 4 so as to sandwich the wafer 1. The exposure light irradiating unit 4 moves the wafer 1 from a retracted position that does not overlap the wafer 1 placed on the turntable 2 along the radial direction of the turntable 2.
Is configured to be movable by the exposure light irradiation unit drive system 5 up to the peripheral portion position. The controller 7 controls the table driving system 3 and the exposure light irradiation unit driving system 5. The wafer 1 is placed on the turntable 2 and rotated,
The amount of exposure light, which is not blocked by the peripheral edge of the wafer 1, of the exposure light irradiated from the exposure light irradiation unit 4 by the wafer end surface detection sensor 11 is measured. As a result, the wafer 1
Detect the end face position. And based on the detection signal,
The exposure light irradiating section 4 is moved in the radial direction of the wafer while being controlled by the controller 7, and the exposure of a constant width is performed with reference to the position of the end face of the wafer 1.

[0004]

However, in the above-described conventional substrate peripheral edge exposure method, since the exposure is performed based on the position of the end face of the wafer, the following problem has occurred. That is, a deformed portion such as an orientation flat or a notch, which is different from the circular shape which is the end surface shape of the wafer, is formed on the peripheral portion of the wafer. Therefore, when the orientation flat 1a is formed at the periphery of the wafer as shown in FIG. 6A, even if the exposure is performed with the exposure width w from the end face of the wafer toward the center Cw of the wafer, the orientation flat The distance between the exposure area boundary 11 at the flat 1a portion and the end face of the orientation flat 1a is w ·
cos θ, there is a problem that the exposure area does not have a desired shape. Further, even when it is necessary to perform exposure with a constant exposure width w regardless of the presence of the notch 1e or the like,
As shown in FIG. 6B, the desired circular shape 10k is not formed at the notch 1e, and the shape 12 conforms to the shape of the notch 1e.
Was formed. Accordingly, it is an object of the present invention to provide a substrate peripheral edge exposure method that can obtain a desired exposure shape irrespective of a wafer end face shape.

[0005]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention relates to a method for exposing a peripheral portion of a flat circular substrate coated with a photosensitive agent by a light irradiation system. The detector measures the coordinate value of the peripheral portion, calculates the center coordinate value of the substrate based on the coordinate value of the peripheral portion, and exposes an exposure area that is a predetermined distance radially away from the central coordinate value of the substrate. Substrate edge exposure method.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A description will be given of a substrate edge exposure method according to one embodiment of the present invention. FIG. 1 is a schematic cross-sectional view of a substrate edge exposure apparatus that performs the substrate edge exposure method of the present embodiment. In FIG. 1, a wafer 1 is placed on a rotary table 2 rotated by a table driving system 3 such that a center Cw of the wafer 1 substantially coincides with a rotation center Ct of the rotary table 2. An exposure light irradiator 4 for exposing the peripheral portion of the wafer 1 placed on the turntable 2 is disposed near the turntable 2 in the lateral direction. The exposure light irradiator 4 includes an exposure light irradiator drive system 5 extending from a retracted position that does not overlap with the wafer 1 placed on the turntable 2 along a radial direction of the turntable 2 to a peripheral position of the wafer 1. It is configured to be movable. The controller 7 controls the table driving system 3 and the exposure light irradiation unit driving system 5. Further, a calibration sensor 6 is arranged at a position where the distance from the rotation center Ct of the turntable 2 is accurately measured and does not overlap with the wafer 1. The calibration sensor 6 measures the amount of exposure light emitted from the exposure light irradiation unit 4 while moving the exposure light irradiation unit 4. The signal from the calibration sensor 6 is transmitted to the controller 7 and subjected to signal processing to calculate the distance between the rotation center Ct of the turntable 2 and the exposure light emitted from the exposure light irradiation unit 4. In addition,
The calibration sensor 6 can simultaneously measure the illuminance of the exposure light.

[0007] Peripheral exposure using the substrate peripheral exposure apparatus of FIG.
Before starting, the wafer 1 is first placed on the turntable 2.
Wafer with respect to the rotation center Ct of the turntable 2 when
1 and the orient formed on the periphery of the wafer 1
Measure the position coordinates of the station flat or notch
You. Eccentricity of wafer 1 and orientation flat
Alternatively, the notch position coordinate value is used for the wafer used in the exposure apparatus.
Measurement using the pre-alignment section of the transport system
Can be. Plan view of pre-alignment part of wafer transfer system
Is shown in FIG. Wafer on rotary table 2 shown in FIG.
Pre-alignment so that it overlaps the periphery
The wafer outer shape detection sensor 9 in the section G is disposed. Wafer outline
The wafer 1 on the turntable 2 is placed above the detection sensor 9.
An outer shape detection light projecting system (not shown) is
You. The wafer 1 on the turntable 2 rotates in the direction of the arrow in the figure.
Of the luminous flux emitted from the outer shape detection
The amount of light not blocked by the peripheral edge of the wafer 1
3 is measured by the external shape detection sensor 9 and
Signal output is obtained. In FIG. 3, the horizontal axis is shown in FIG.
The rotation angle of the turntable 2 and the vertical axis are outside the wafer shown in FIG.
The signal output from the shape detection sensor 9 is shown. Such trust
Rotation table from 1/2 of the difference between maximum and minimum signal output
Of the eccentricity of the wafer 1 with respect to the rotation center Ct of the wafer 2
Can be. In addition, the angular position θ of the projection of the signal output from a
The position coordinates of the notch 1e can be obtained. Note that FIG.
As shown, the eccentric amount of the wafer 1 is during rotation of the turntable 2.
Represents the center coordinate value of the wafer 1 with respect to the center Ct.
You. Eccentricity and notch of wafer 1 thus obtained
Is stored in the controller 7.

In this embodiment, the eccentricity of the wafer 1 and the position coordinate value of the orientation flat or notch are measured using the pre-alignment unit of the wafer transfer system, but the wafer 1 is passed over the sensor array. It is also possible to use a method in which the measurement is performed by imaging the wafer 1 with an image sensor such as a CCD and performing signal processing.

The exposure light irradiation section 4 shown in FIG. 1 is retracted to the outermost position where it does not overlap with the wafer 1 before starting the peripheral exposure. First, a shutter provided in the exposure light irradiating section 4 or the exposure light source section 8 is opened by a command from the controller 7, and the exposure light irradiating section is opened until a photo sensor provided in the calibration sensor 6 detects the exposure light. 4 is moved toward the rotation center Ct of the turntable 2. Further, during this operation, the position coordinates and the illuminance of the exposure light are measured and stored in the controller 7.
Here, the shutter is closed once, and the calculation is performed based on the shape data of the desired peripheral exposure area previously input to the controller 7, the eccentricity of the wafer 1, the position coordinate data of the notch, and the position coordinate data of the exposure light. The exposure light irradiation unit 4 is moved to the position where the exposure light is irradiated.

Next, the shutter is opened again. Then, while rotating the rotary table 2, the exposure light irradiation unit 4 is tracked according to the rotation angle. At this time, as shown in FIG. 4A, the radius component s of the boundary coordinates of the peripheral exposure area is set with reference to the center Cw of the wafer 1, and the angle component θ
Is set based on the shape data of the desired peripheral exposure area and the position coordinate data of the notch. Thus, the peripheral portion of the wafer 1 can be exposed to a desired shape. The rotation speed of the rotary table 2 shown in FIG. 1 is based on the data of the light irradiation amount necessary for the peripheral exposure previously input to the controller 7 and the movement of the exposure light irradiation unit 4 toward the center of the wafer 1. The calculation is performed based on the illuminance data of the exposure light measured during.

The table driving system 3 is constituted by, for example, combining a motor and a rotary encoder. The table driving system 3 detects the angle origin and exposes the peripheral portion of the wafer to a desired shape in the rotation direction of the rotary table 2. It has the resolution required to detect the amount of rotation. The exposure light irradiation unit drive system 5 is configured by combining, for example, a motor and a linear encoder.
In the radial direction, there is a resolution necessary for detecting the coordinate origin and detecting the moving amount of the exposure light irradiation unit 4 for exposing the wafer peripheral portion to a desired shape.

As described above, the rotation center C of the rotary table 2
The data of the eccentricity of the wafer 1 and the position coordinates of the deformed portion with reference to t are obtained, the radius component of the peripheral exposure area is set with the center Cw of the wafer 1 as a reference, and the angle component is input to the controller 7 in advance. A desired exposure shape is obtained regardless of the end surface shape of the wafer 1 by setting the shape of the peripheral exposure region by setting based on the shape data of the desired peripheral exposure region and the data of the position coordinates of the deformed portion. Can be. Further, even if the external dimensions of the wafer vary, the non-exposed portion can be formed in a constant shape.

Next, an embodiment in which the peripheral edge exposure is performed by using the peripheral edge exposure method according to the present invention will be described with reference to FIGS.
It is shown in (c). FIG. 4A shows a first embodiment in which peripheral exposure is performed on a wafer having an orientation flat formed on the peripheral portion. Wafer 1 measured in advance
Based on the eccentricity and the position coordinate data of the orientation flat 1a, the exposure light irradiating section 4 is tracked by defining the exposure area boundary 10 by the distance s from the center Cw of the wafer 1 and the rotation angle θ from the angle origin. The exposure area boundary 10a other than the orientation flat 1a is formed in a circular shape with a radius r around the center Cw of the wafer 1. On the other hand, the exposure area boundary 10b of the orientation flat 1a is the orientation flat 1a.
Is formed in a straight line corresponding to the shape of. Now, let the radius passing through the midpoint 1c of the orientation flat 1a be the angle origin Oa and let the counterclockwise direction be +. Further, when the central angle of the orientation flat 1a and 2 [Theta] _1, both end portions 1b, respectively theta ₁ 1d the angle coordinate values, represented by 2π-θ _1. Therefore, the relationship between the distance s from the wafer center Cw and the rotation angle θ is 0 ≦ θ <θ ₁ and 360 ° −θ ₁ <θ.
At <360 °, In θ ₁ ≦ θ ≦ 360 ° −θ ₁ , What is necessary is just to set so that it may satisfy.

FIG. 4B shows a second embodiment in which peripheral exposure is performed on a wafer having a notch formed in the peripheral portion.
In this embodiment, the exposure area boundary 10 is formed in a circular shape having a radius r around the center Cw of the wafer 1 including the notch 1e. For example, if the radius passing through the notch 1e is the angle origin Oa, the distance s from the wafer center Cw and the rotation angle θ
Is 0 ≦ θ <360 °, What is necessary is just to set so that it may satisfy.

FIG. 4C shows a third embodiment in which peripheral exposure is performed on a wafer having a notch formed in the peripheral portion.
In this embodiment, the exposure region boundary 10 is formed such that rectangular recesses in contact with a circle having a radius r ₂ centered on the center Cw of the wafer 1 are formed at every 90 ° step including the notch 1e. The boundary is formed as a circle with a radius r ₁ centered on the center Cw of the wafer 1. This is performed when only the photosensitive agent at the portion where the tip of the transfer arm contacts is extensively removed. In this embodiment, for example, the radius passing through the notch 1e is defined as the angle origin Oa, and the central angle of the concave portion is defined as 2θ _2.
Assuming that the counterclockwise direction is +, the angular coordinate values at both ends of each concave portion are 10c in order from the angular origin Oa:
θ ₂ , 10d: 90 ° −θ ₂ , 10e: 90 ° + θ ₂ , 1
0f: 180 ° −θ ₂ , 10 g: 180 ° + θ ₂ , 10
h: 270 ° -θ ₂ , 10i: 270 ° + θ ₂ , 10j:
Represented by 360 ° -θ _2. Therefore, the wafer center C
The relationship between the distance s from w and the rotation angle θ is 0 ≦ θ <θ ₂ , 90 ° −θ ₂ <θ <90 ° + θ ₂ , 180 ° −θ ₂ <θ <180 ° + θ ₂ , 270 ° − θ ₂ <θ <270 ° + θ ₂ , 360 ° −θ ₂ <
When θ <360 °, θ ₂ ≦ θ ≦ 90 ° −θ ₂ , 90 ° + θ ₂ ≦ θ ≦ 180 ° −
θ ₂ , 180 ° + θ ₂ ≦ θ ≦ 270 ° −θ ₂ , 270 ° + θ ₂ ≦ θ ≦ 360 ° −θ ₂ , What is necessary is just to set so that it may satisfy.

[0016]

As described above, according to the present invention, since the peripheral exposure area is formed with reference to the center of the wafer, the peripheral exposure can be performed in a desired exposure shape regardless of the shape of the end face of the wafer. Further, even if the external dimensions of the wafer vary, the non-exposed portion can be formed in a constant shape.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view of a peripheral edge exposure apparatus that performs a substrate peripheral edge exposure method according to one embodiment of the present invention.

FIG. 2 is a plan view showing a configuration of a pre-alignment unit of the wafer transfer system.

FIG. 3 is a diagram showing signals obtained from a wafer profile sensor;

FIGS. 4A and 4B are diagrams for explaining the substrate edge exposure according to the first embodiment, the second embodiment, and the third embodiment; FIG.

FIG. 5 is a schematic cross-sectional view of a substrate peripheral exposure apparatus that performs a conventional substrate peripheral exposure method.

FIG. 6 is a view for explaining substrate peripheral exposure by a conventional substrate peripheral exposure method.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Wafer 2 ... Rotary table 3 ... Rotary table drive system 4 ... Exposure light irradiation part 5 ... Exposure light irradiation part drive system 6 ... Calibration sensor 7 ... Controller 8 ... Exposure light source part 9 ... Wafer outer shape detection sensor 11 ... Wafer Edge detection sensor Ct: Rotary table center Cw: Wafer center

Claims (5)

[Claims] 1. A substrate peripheral exposure method for exposing a peripheral portion of a circular substrate having a planar shape coated with a photosensitive agent by a light irradiation system, wherein a coordinate value of the peripheral portion is measured by an outer shape detector. A center coordinate value of the substrate is calculated based on the coordinate value, and an exposure area is exposed at a predetermined distance in a radial direction from the center coordinate value of the substrate. 2. The substrate has a deformed portion different from the circle at a part of the peripheral portion, and measures a position coordinate value of the deformed portion of the substrate, and determines a position of the deformed portion with respect to the center coordinate value of the substrate. 2. The method according to claim 1, wherein the position coordinate value is calculated as an angular position, and the exposure area is exposed by changing the predetermined distance according to the angular position corresponding to the deformed portion. . 3. The method according to claim 1, wherein a shape of the deformed portion is calculated from the position coordinate values of the deformed portion, and the exposure area is exposed using the angular position information and the shape. The peripheral edge exposure method of the description. 4. A method according to claim 1, wherein the coordinate value of the peripheral portion is measured by rotating the substrate around an axis perpendicular to the plane of the substrate. 5. The substrate peripheral exposure according to claim 1, wherein the substrate is rotated about an axis perpendicular to the substrate plane to expose the exposure area at the peripheral portion. Method.