JPH0828322B2 - Wafer edge exposure equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention is intended to remove unnecessary resist around a resist applied on a silicon wafer in a developing process when forming a fine pattern on an IC, an LSI, or the like. Wafer peripheral exposure apparatus.

[Prior Art] When forming a fine pattern in the manufacture of ICs, LSIs, etc., apply a resist to the surface of a silicon wafer,
On the other hand, exposure and development are performed to form a resist pattern, and then using the created resist pattern as a mask, processes such as ion implantation, etching, and lift-off are sequentially performed.

Usually, the resist is applied by spin coating. In the spin coating method, the wafer is rotated while pouring the resist solution to the center position of the wafer surface, and the resist is applied to the entire surface of the wafer by centrifugal force.

However, it is not the entire surface of the wafer that is utilized for processing. In particular, the peripheral portion is not generally used because it is held during wafer transfer or is distorted even if the circuit pattern is exposed.

Then, leaving the unused resist on the peripheral portion of the wafer as it is causes various problems. That is, if the peripheral portion of the pattern is mechanically gripped and held, or if the peripheral portion of the wafer rubs against the wall of a container such as a wafer cassette, it becomes a source of dust. As described above, the fact that the unnecessary resist remaining on the peripheral portion of the wafer is turned into dust to reduce the yield is a serious problem especially as the integrated circuits are becoming highly functional and miniaturized.

Therefore, in order to remove the unnecessary resist on the wafer peripheral portion that remains after such development, separately from the exposure process for pattern formation, the wafer peripheral exposure is performed separately to remove the unnecessary resist on the wafer in the developing process. Is being done.

In this wafer edge exposure, light guided by an optical system is applied to the periphery of the semiconductor wafer coated with a resist to expose it. With respect to this irradiation, it is necessary to expose a certain amount or more. The exposure amount in that case is the product of the illuminance and the exposure time. That is, in order to increase the exposure amount, either increase the illuminance or lengthen the exposure time. However, the exposure time is required to be as short as possible in order to increase the productivity, and the exposure time cannot be increased. On the other hand, when the illuminance is increased to obtain the required exposure amount, there is a problem that the resist foams.

Therefore, conventionally, the wafer is rotated a plurality of times while being exposed with an illuminance such that the resist does not foam.
A predetermined exposure amount is exposed.

[Problems to be Solved by the Invention] By the way, in the above-mentioned conventional technique, when the spin coating method is used, the resist is not always uniformly applied to the peripheral portion of the wafer, and the resist is thick. A part and a thin part occur, and in particular, the part of the orientation flat tends to be thicker than other parts.

Conventionally, in order to remove such a resist, it was necessary to rotate the wafer until the thick portion of the resist was removed. That is, the exposure amount corresponding to the thick portion of the resist dominates the processing time, and the thin portion of the resist continues to be exposed even though the removal is completed, resulting in a long processing time. Was causing the problem.

SUMMARY OF THE INVENTION An object of the present invention is to provide a wafer peripheral exposure apparatus capable of shortening the processing time in view of the above-mentioned conventional circumstances.

[Means for Solving the Problems] In order to achieve the above object, the present invention provides a light source, an optical system that guides light from the light source to expose the periphery of the wafer, and a processing table on which the wafer is mounted. And a controller for controlling the processing table to rotate in a fixed direction, the controller controls the processing table to move in a fixed direction with respect to a specified region in the peripheral portion of the wafer. A means for reciprocating and exposing only the specific region is provided by rotating in the opposite direction.

[Operation] According to the above-described means, in the peripheral portion of the semiconductor wafer, which is desired to be removed as unnecessary resist, only the thick portion of the resist is set as the specific region, and only this region is reciprocally exposed. And As a result, the total exposure time can be significantly reduced.

[Embodiment] FIG. 1 is a block diagram showing an embodiment of a wafer peripheral exposure apparatus according to the present invention.

In FIG. 1, reference numeral 1 denotes a wafer whose peripheral portion is subjected to exposure processing, 2 denotes a stage as a processing table for placing the wafer 1 thereon for raising and lowering and rotating, and 3 processing a signal system to control a drive system. Controller 4, a stage drive mechanism for driving the stage 2 to move up and down and rotate 5, a stage encoder 2 and the like.
A stage rotation angle reading mechanism for reading the rotation angle of the wafer, and an exposure unit 6 for exposing the peripheral portion of the wafer. The exposure unit 6 has a light guide fiber 11,
Light emitting element 13 for detecting the edge of wafer 1 and light emitting element
A light receiving element 17 for receiving the light from 13 is provided.
Then, the light guide fiber 11 has an emitting end at the tip thereof.
Have twelve.

Reference numeral 7 is a wafer transfer system for transferring a wafer, 8 is a unit drive mechanism for driving the exposure unit 6, 9 is a shutter drive mechanism for driving the shutter 10 for movement, and 10 is a shield or release of the incident end of the light guide fiber 11. Shutter,
Reference numeral 14 is a flat reflecting mirror for guiding the light to the light guide fiber 11, 15 is an elliptical focusing mirror for guiding the light from the light source to the flat reflecting mirror 14, and 16 is a short arc type mercury lamp.

Next, the operation of the embodiment having the above configuration will be described.

First, the wafer 1 is transferred to the stage 2 by the wafer transfer system 7.
Then, the stage 2 is raised by the stage drive mechanism 4. From this state, first, the shutter driving mechanism 9 is driven by the controller 3 to open the shutter, and the light from the plane reflecting mirror 14 is introduced into the light guide fiber 11. The wafer 1 is rotated by the stage drive mechanism 4 while exposing the light from the light source unit. This exposure is performed by introducing the light of the mercury lamp 16 into the entrance end of the light guide fiber 11 through the elliptical focusing mirror 15 and the plane reflecting mirror 14 and letting it exit from the exit end 12.

At this time, the wafer 1 is formed by the light emitting element 13 and the light receiving element 17.
Edge of the wafer 1 to detect the mounting state of the wafer 1 on the stage 2. The placement state indicates a shift between the center of the stage 2 and the center of the wafer 1 when the wafer 1 is transferred to the stage 2. The detected value of the mounting state is sent to the controller 3 and stored in the attached memory. For example, the position of the start of the peripheral exposure and the position of the orientation flat are stored. The exposure unit 6 can be finely moved in the radial direction of the wafer 1.
Exposure of the peripheral portion is performed according to the mounting state of. With this mechanism, even if the wafer 1 is placed on the stage 2 with a shift, exposure can be performed without any problem. In this way, the wafer 1 can be rotated, and the peripheral portion of the exposure unit 6 can be finely moved in the radial direction while exposing the width to be exposed. Can handle only the width of.

Next, with reference to FIGS. 2 and 3, an example of the reciprocal exposure of the present invention will be specifically described.

2 is an enlarged view of the wafer 1, and FIG. 3 is a wafer 1.
FIG. 3 is a setting diagram of parameters for exposing the.

As shown in FIG. 2, the wafer 1 is provided with an orientation flat 20 having end points A and B at a part of its periphery. An exposure width w is set on the peripheral portion 21 of the wafer 1 other than the orientation flat 20. The orientation flat 20 is within an angle θ from the center of the wafer 1.

In the present embodiment, the exposure time of the orientation flat 20 where the resist becomes thicker is increased and the exposure of other portions is minimized. For this purpose, the parameters shown in FIG. 3 are used. The specification of this parameter is input to the controller 3 using a keyboard (not shown) or the like before the operation is started.

In FIG. 3, L / H indicates the intensity (Low / High) of the illuminance. For example, L is a numerical value such that the resist does not foam.
1000 mW / cm ² and H are 3000 mW / cm ² . Further, the width w indicates the exposure width of the peripheral portion of the wafer 1, S.ANG is the angle of the start position for rotating the wafer 1, A.ANG is the exposure angle, and RTN is the presence / absence of reciprocal exposure ("1" indicates reciprocation. , "0" is only in one direction),
TURN represents the number of revolutions, and TIME represents the time (second / revolution) required to rotate the wafer once.

Explaining the peripheral exposure of the wafer, first, while the wafer 1 is rotated by one rotation (360 °) by the stage 2, while the peripheral edges are detected by the light emitting element 13 and the light receiving element 17, the orientation flat 20 of the wafer 1 is detected. The midpoint between points A and B is obtained (the method for obtaining the midpoint is described in, for example, Japanese Patent Application No. 1-243492, which has already been filed by the applicant of the present application).

Next, reciprocal exposure is performed by using the orientation flat 20 up to the point B as a specific area starting from the point A in FIG. Then, from the point B to the point A of the peripheral portion 21, the normal unidirectional exposure is performed.

Here, as shown in FIG. 3, the exposure of the specific region is performed by the exposure method, and the exposure from the point B to the point A of the peripheral portion 21 is performed by the exposure method. That is, the starting point A is set to 340 ° (referenced to the orientation flat 20 obtained by the first peripheral detection), the exposure width is w, the rotation angle θ is 40 °, the reciprocating exposure is performed (designation is “1”), and the rotation is performed. Several TURNs are specified 5 times and the exposure speed is 10 seconds / revolution). As a result, the wafer 1 rotates in the direction 22 from the point A, and the exposure is started with the width w. Incidentally, 12 'shown in FIG. 3 indicates an irradiation region from the emitting end 12.

At the point B where the wafer 1 is rotated by the rotation angle of 40 °, the wafer 1 is reversely rotated in the direction 23. Then, when the wafer 1 returns to the point A, it rotates in the direction 22 again. After performing such reciprocal exposure five times on the orientation flat 20, the wafer 1 is rotated in the direction 22 from the point B, and the peripheral portion 21 up to the point A is exposed with the width w.

At this time, the thick orientation flat 20 of the resist is reciprocally exposed 5 times at the illuminance L (that is, 10 exposures in total), and the thin peripheral portion 21 of the resist is
The illuminance is set to H and the range of 320 ° from the position of 20 ° is exposed only once.

In the above description, the resist of the orientation flat 20 is usually thicker than that of the peripheral portion 21 (for example, the resist of the orientation flat 20 is 10 μm).
m and other portions are 2 μm), the orientation flat 20 is reciprocally exposed. However, the present invention is not limited to this, and reciprocal exposure may be performed with a portion other than the orientation flat 20 as a specific region. Wafer 1
Means for reciprocating exposure by rotating the stage 2 in one direction or in the opposite direction with respect to the specific area.

In addition, as a special case, the starting angle 360 °, the rotation angle 360
If you specify °, you can make one round exposure.

Further, in the above-described embodiment, the light of the light source is guided to the exposure unit by using the light guide fiber, but the present invention is not limited to this, and an optical system such as a lens may be used.

[Effects of the Invention] As is apparent from the above, according to the present invention, a light source, an optical system that guides light from the light source to expose the periphery of the wafer, a processing table on which the wafer is mounted, and this processing. In a wafer peripheral exposure apparatus having a controller for controlling the table to rotate in a fixed direction, the controller rotates the processing table in a specified direction in a specified region in the peripheral portion of the wafer, Since the means for reciprocally exposing only the specific region is provided, the overall exposure time can be greatly shortened.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of a wafer peripheral exposure apparatus according to the present invention, FIG. 2 is an enlarged view of a wafer, and FIG. 3 is a setting diagram of parameters for exposing a wafer. In the figure. 1: wafer, 2: stage 3: controller 4: stage drive mechanism 5; stage rotation angle reading mechanism 6: exposure unit 7: wafer transfer system 8: unit drive mechanism 9: shutter drive mechanism 11: light guide fiber 12: emission end , 13: Light emitting element 16: Mercury lamp, 17: Light receiving element

Claims (1)

[Claims] 1. A light source, an optical system for guiding light from the light source to expose the periphery of a wafer, a processing table on which the wafer is placed, and a controller for controlling the processing table to rotate in a fixed direction. In the wafer periphery exposure apparatus having: a controller, the controller rotates the processing table in a direction opposite to a certain direction with respect to a designated specific region of the peripheral portion of the wafer, and reciprocally exposes only the specific region. A wafer edge exposure apparatus comprising: