JPH04133312A - Wafer-periphery aligner - Google Patents

Abstract

PURPOSE:To shorten the entire exposure time to a large extent by rotating a treating stage for mounting a wafer in one direction or in the reverse direction with respect to the specified region with the controller of a wafer-periphery aligner, and performing exposure in the reciprocating mode. CONSTITUTION:At first, a wafer 1 is rotated by one rotation with a stage 2. Under this state, the periphery is detected with a light emitting element 13 and a photodetector 17. Thus, the midpoint between A-B of an orientation flat 20 of the wafer 1 is obtained. Then, with the point A as a starting point, the orientation flat 20 up to the point B undergoes reciprocating exposure as the specified region. Namely, the wafer 1 is rotated in the direction 22, and the exposure for a width (w) 13 started. At the point B where the wafer 1 is rotated by 40 deg., the wafer 1 is rotated in the reverse direction 23. When the wafer 1 is returned to the point A, the wafer 1 is rotated in the direction 22 again. The reciprocating exposure such as this is performed by five times for the orientation flat 20. Thereafter, the wafer 1 is rotated in the direction 22 from the point B. A peripheral part 21 up to the point A is exposed for the width (w).

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is a method for removing unnecessary resist around the periphery of a resist coated on a silicon wafer in a developing process when forming fine patterns on ICs, LSIs, etc. The present invention relates to a wafer peripheral high-light device.

[Prior art] When forming fine patterns in the manufacture of ICs, LCr, etc., a resist is applied to the surface of a silicon wafer, etc., and then exposed and developed to form a resist pattern, and then the created resist pattern is Processing such as ion implantation, etching, and lift-off is performed sequentially using the mask as a mask.

Usually, the resist is applied by a spin code method. In the spin code method, the resist solution is poured onto the center of the wafer surface while the ware is rotated, and resist is applied to the entire wafer surface using centrifugal force.

However, not the entire surface of the wafer is used for processing. In particular, the peripheral area is used for holding the wafer during transportation, or
Even if the circuit pattern is exposed, it will be distorted, so -
Do not use for boat fishing.

Leaving this unused resist around the wafer as it is causes various problems. That is, if the periphery of the pattern is mechanically gripped and held, or if the wafer periphery rubs against the wall of a container such as a wafer cassette, this becomes a source of dust. in this way,
The situation in which unnecessary resist remaining on the periphery of the wafer becomes dust and reduces yield is becoming a serious problem, especially now that integrated circuits are becoming more sophisticated and smaller.

Therefore, in order to remove unnecessary resist on the wafer periphery that remains even after such development, wafer periphery exposure is performed, which is a separate exposure process to remove unnecessary resist on the wafer in the development process, in addition to the exposure process for pattern formation. is being carried out.

This wafer peripheral exposure is performed by rotating the semiconductor wafer coated with resist and irradiating the peripheral part with light guided by an optical system. For this irradiation, a certain-window or higher exposure is required. The exposure amount in this case is the product of illuminance and exposure time. That is,
In order to increase the amount of exposure, either increase the illuminance or lengthen the exposure time. However, in order to increase productivity, it is required to shorten the exposure time as much as possible, and it is not possible to increase the exposure time. on the other hand,
If you try to increase the illuminance to obtain the necessary high amount of light, you have the problem of foaming of the resist.

For this reason, in the past, the urethane was rotated several times while being exposed to light at a level that did not cause foaming in the resist.
A predetermined amount of light is exposed.

[Problems to be Solved by the Invention] By the way, in the above-mentioned conventional technology, when the spin code method is used, the resist is not always uniformly applied to the periphery of the wafer, and the resist is thick and There are some parts and thin parts, and in particular, the orientation flat part is thicker than other parts.

Conventionally, removing such resist required rotating the wafer until the thicker portions of the resist were removed. In other words, the exposure amount for the thicker parts of the resist governs the processing time, and the thinner parts of the resist continue to be woven even after removal has been completed2, resulting in longer processing times. It was causing problems.

SUMMARY OF THE INVENTION An object of the present invention is to provide a wafer peripheral exposure apparatus that can shorten processing time, and is made in view of the above-mentioned actual state of the prior art.

[Means for Solving the Problems] In order to achieve the above object, the present invention comprises: a light source; an optical system that guides light from the light source to expose the periphery of a wafer;
A wafer peripheral exposure apparatus has a processing table on which the wafer is placed, and a controller that controls rotation of the processing table in a certain direction. The apparatus includes means for rotating the processing table in a direction opposite to a fixed direction with respect to a specific area and reciprocatingly exposing only the specific area.

[Operation] According to the above-mentioned means, in the peripheral part of the semiconductor wafer where the unnecessary resist is to be removed, only the thick part of the resist is designated as a specific area, only this area is subjected to reciprocating exposure, and the other areas are exposed for the minimum number of times. shall be. This allows the overall exposure time to be significantly shortened.

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

In Figure 1, 1 is a wafer whose peripheral part undergoes exposure processing, 2 is a stage as a processing table on which the wafer 1 is placed and moves up and down and rotates, and 3 processes a signal system and controls a drive system. 4 is a stage drive mechanism that drives the stage 2 to raise, lower, and rotate the stage 2; 5 is a stage rotation angle reading mechanism configured using a rotary encoder and the like and reads the rotation angle of the stage 2; 6 is a wafer periphery; This is an exposure unit that exposes the area. This exposure unit 6 includes a light guide fiber 11 inside thereof.
A light emitting element 13 for detecting the edge of the wafer 1. and a light receiving element 17 that receives light from the light emitting element 13. The light guide fiber +1 has an output end 12 at its tip.

7 is a wafer transport system that transports the wafer; 8 is a unit drive 119 that drives the exposure unit 6; a shutter drive side 110 that drives the shack 10 for movement; a shutter that blocks or releases the incident end of the light guide fiber 11;
14 is a plane reflecting mirror for guiding light to the light guide fiber 11; 15 is an elliptical collector mirror for guiding light from the light source to the plane reflecting mirror 14; and 16 is a short arc type mercury lamp.

Next, the operation of the embodiment with the above configuration will be explained.

First, when the wafer 1 is placed on the stage 2 by the wafer transport system 7, the stage 2 is raised by the stage drive mechanism 4. From this state, first, the shutter drive 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 a stage drive mechanism 4 while being exposed to light from a light source. This exposure (↓.

The light from the mercury lamp 16 is transferred to the elliptical condensing mirror 15 and the flat reflecting mirror 1.
4 into the input end of the light guide fiber 11,
This is done by emitting light from the emitting end 12.

At this time, the edge of the wafer 1 is detected by the light emitting element 13 and the light receiving element 17, and the state of the wafer 1 placed on the stage 2 is detected. This mounting state refers to the center of stage 2 when wafer 1 is transferred to stage 2, and the center of wafer 1 when it is transferred to stage 2.
indicates the deviation from the center of The detected value of this placement state is sent to the controller 3 and stored in the attached memory. For example, the starting position for peripheral exposure and the orientation flat position are stored. The exposure unit 6 is able to move slightly in the radial direction of the wafer 1, and exposes the periphery of the wafer 1 in accordance with the mounting state of the wafer 1. With this mechanism, even if the wafer 1 is placed on the stage 2 in a shifted manner, exposure can be performed without any problem. this'
In this way, the wafer 1 can be rotated, and the high-light unit 6 can slightly move the periphery of the wafer 1 in the radial direction to expose the desired width, and even in the orientation flat, the fine movement of the exposure unit can accurately expose the desired width. Only the width can be processed.

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

FIG. 2 is an enlarged view of the wafer 1, and FIG. 3 is a diagram showing parameter settings for exposing the wafer 1.

As shown in FIG. 2, the wafer 1 has an orientation flat 20 having end points A and B at a portion of its periphery. For this wafer 1, an exposure width W is set in a peripheral portion 21 of the portion other than the orientation flat 20. Orientation flat 20 is within an angle θ from the center of wafer 1 .

In this embodiment, the exposure time of the orientation flat 20 where the resist is thick is increased, and the exposure of other parts is minimized, and for this purpose, the parameters shown in FIG. 3 are used. This parameter designation is input into the controller 3 using a keyboard (not shown) or the like before starting the operation.

In Figure 3, L/H indicates the intensity of illuminance (Low/Hi
For example, L is 10,100 O/cm, H is 3,000 as a value that does not cause foaming of the resist.
m W / cm ”.Furthermore, the width W is the width of the wafer l
, S and ANG are the starting position angles for rotating the wafer 1, A and ANG are the exposure angles, and R
TN is whether or not there is reciprocating exposure (“l” is reciprocating exposure, °0 is only in one direction), TURN is the number of rotations, and TIME is the number of wafers
The time required for rotation (seconds/rotation) is shown in each case.

Here, to explain the peripheral exposure of the wafer, first,
While the wafer 1 is rotated by one rotation (360°) by the stage 2, the peripheral edge is detected by the light emitting element 13 and the light receiving element 17.

Find the midpoint between A-8 of the orientation flat 2o of wafer l (For how to find this midpoint, see, for example, Japanese Patent Application No. 1-243492, which the applicant has already filed.
(described in the issue).

Next, reciprocating exposure is performed with the orientation flat 20 starting from point A in FIG. 2 and ending at point B as a specific area. Then, the area from point B to point A in the peripheral area 21 is subjected to normal unidirectional exposure.

Here, as shown in FIG. 3, the specific area is exposed according to the exposure method (2), and the peripheral area 21 from point B to point A is exposed by the exposure method (2). In other words, the starting point A is 340'', the orientation flat 20 obtained from the initial peripheral configuration is used as a reference, the exposure width is W, the rotation angle θ is 40°, and there is a round trip tremor (the designation is “1”).
”).

The number of rotations TURN is specified as 5 times, and the exposure speed is specified as 10 seconds (71 rotations). As a result, the wafer 1 is rotated in the direction 22 from the point A, and exposure is started with the width W. Note that 12' shown in FIG. 3 indicates the irradiation area from the output end 12.

At point B, where wafer 1 has rotated by a rotation angle of 40'', wafer 1 rotates in the opposite direction in direction 23.
When it returns to the point, it rotates in direction 22 again. After performing such reciprocating exposure five times on the orientation flat 20, the wafer l is rotated from point B in direction 22, and
The peripheral portion 21 up to the point is exposed with a width W.

At this time, the thick orientation flat 20 of the resist is exposed to the illuminance back and forth 5 times (that is, 10 times in total), and the thin peripheral part 21 of the resist is exposed at an angle of 20° with the illuminance H by the method (2). A range of 320' from the position is exposed only once.

Note that in the above description, the resist of the orientation flat 20 is usually thicker than that of the peripheral part 21 (for example, the resist of the orientation flat 20 is thicker than the peripheral part 21).
Since the orientation flat 20 is subjected to reciprocating exposure (0μ is false and the other portion is 2μ1Il), the orientation flat 20 is not limited to this, and reciprocating exposure may be performed using a portion other than the orientation flat 20 as a specific area. In this way, means for rotating the stage 2 in one direction or in the opposite direction with respect to a specific area of the wafer 1 and emitting 111 g of light in the opposite direction is constituted.

Furthermore, as a special case, starting angle 360'' rotation angle 3
If 60° is specified, -the same high light can be obtained.

In addition, in the above-mentioned example, the light guide fiber was used to guide the light from the light source to the straw light part, but the invention is not limited to this.
For example, an optical system such as a lens may be used.

[Effects of the Invention] As is clear from the above, the present invention includes a light source, an optical system that guides light from the light source to expose the periphery of a wafer, a processing table on which the wafer is placed, and this processing table. In the wafer peripheral exposure apparatus, the controller rotates the processing table in a certain direction with respect to a designated specific area in the peripheral area of the sea urchin; Since means for reciprocating exposure of only the specific area is provided, the overall exposure time can be significantly shortened.

[Brief explanation of the drawing]

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 diagram showing parameter settings for exposing the wafer. Figure Middle: Wafer 2; Stage 3: Controller 4: Stage drive mechanism 5; Stage rotation angle reading mechanism 6: W optical unit 7; Wafer transport system 8: Unit drive mechanism 9: Shutter drive mechanism 11 Nilight guide fiber 12: Output end 13: Light-emitting element 16: Mercury lamp 17: Light-receiving element Agent Patent attorney 1) Kita Takeharu Procedural amendment (voluntary) November 1, 1990, No. 254224 of 1990 Figure 1, Specifications "...LCI..." written in the third line of page 2 of the book.
Correct it to "...LSI...". 2. The silicon wafer described in the 4th line of page 2 of the same
・” should be corrected to “…silicon wafer…”. 3. In the 10th line of page 2 of the same document, ``...the spin code method uses the center of the wafer surface...'' is corrected to ``...the spin code method uses the center of the wafer surface...''. 4. Correct "...Rotate the wafer while pouring the resist solution" to "...Rotate the wafer while pouring the resist solution..." in the 11th line of the second page of the same page.

Claims (1)

[Scope of Claims] 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 placed, and a controller that controls the rotation of the processing table in a fixed direction. In the wafer peripheral exposure apparatus, the controller rotates the processing table in a direction opposite to a fixed direction with respect to a specified specific area in the peripheral area of the wafer, and exposes only the specific area back and forth. A wafer peripheral exposure apparatus characterized by comprising means.