JPH0380528A - Periphery exposure device for wafer - Google Patents

Abstract

PURPOSE:To reduce sag at the edge of a resist layer by aligning a wafer on a wafer stage, and step exposing it around the corrected center of the wafer formed at a position corresponding to the center of the rotary shaft of the stage by means of a sector-shaped exposure beam on the same radius. CONSTITUTION:A wafer 2 is placed on a wafer stage 1, moved by using rotating means 11, X-axis moving means 12 and Y-axis moving means 13, and two points on the orientation flat part 21 of the wafer 2 and one point on the circumference are aligned to be brought into coincidence with the positions of three sensors provided on an alignment unit 3. Then, the wafer 2 is sucked by using wafer elevating/lowering means 4 to raise it from the stage 1, the stage 1 is returned to an initial reference position, and the wafer 2 is again placed on the stage 1. Thereafter, the wafer 2 is step exposed with a sector-shaped exposure beam 57 radiated from a condensing lens 51 while rotating by an angle theta at a time around the corrected center by using the means 11. Thus, the edge of the remaining resist layer is not sagged, but it becomes a right circle on the outer periphery.

Description

[Detailed Description of the Invention] [Summary] Regarding a wafer peripheral exposure device used to remove a resist layer formed on a wafer from a peripheral area of the wafer, The purpose of the present invention is to provide a peripheral exposure device for a wafer, which prevents the edges of the remaining resist layer from sagging when removing the resist layer and makes the outer circumference a perfect circle. A wafer stage has a rotation means for rotating the wafer, an X-axis movement means for moving the wafer in the X-axis direction, and a Y-axis movement means for moving the wafer in the Y-axis direction, and a reference wafer is placed on the wafer stage. When the reference wafer is placed so that the center of the reference wafer coincides with the rotational axis center of the wafer stage, at least three An alignment unit having an alignment sensor, a wafer lifting means for lifting and lowering the wafer onto the wafer stage, and a rotatable condensing lens, the distance between the condensing lens and the center of the wafer stage. has adjustable exposure light generating means, and the exposure beam irradiated onto the wafer from the condensing lens of the exposure light generating means has a fan shape, and the curvature of the arc of the fan shape is as described above. It is constructed with a wafer peripheral exposure device whose curvature is approximately the same as that of the wafer.

[Industrial application field]

The present invention relates to a wafer peripheral exposure apparatus used to remove a resist layer formed on a wafer from a peripheral region of the wafer.

[Conventional technology]

In the manufacturing process of semiconductor devices, a photolithography process is required in which a resist layer is formed on a wafer, and a resist pattern is formed by exposure and development using a mask. If the layer is not removed, when the wafer is placed in the carrier, the resist will come into contact with the grooves of the carrier and peel off, causing dust generation. A wafer peripheral exposure device is a device that exposes the periphery of a wafer to remove a resist layer around the wafer.

A conventional wafer peripheral exposure apparatus will be explained using FIGS. 10 and 11. FIG. 10 is a plan view,
FIG. 11 is a side view of the wafer 2.
This is a wafer stage having a vacuum chuck on which a wafer is placed, and is rotated by rotation means 11. Reference numeral 5 denotes an exposure light generating means, which guides light generated by a light source 55 such as a mercury lamp to a condenser lens 51 with a slit via an optical fiber 53 to form a rectangular exposure beam and irradiates it onto the wafer 2 .

The distance of the condensing lens 51 from the center of the wafer stage l is controlled by a condensing lens moving means 56. 6 is a wafer edge detection means, which includes a CCD line sensor 6;
1 and a controller 62 that processes this signal and stores the wafer edge position.

The wafer 2 is placed on the wafer stage l, and the edge of the wafer 2 is rotated using the rotating means 11.
The D-line sensor 61 detects the signal, the controller 62 performs image processing to store the position of the wafer edge, and based on the stored wafer edge position information, the condenser lens moving means 56 is controlled to align the condenser lens 51 with the peripheral part of the wafer 2, and expose a region having a constant width from the edge of the wafer 2.

[Problem to be solved by the invention]

By the way, if the wafer 2 is rotated without irradiating the peripheral area of the wafer 2 with the rectangular exposure beam 57, the seventh
The area between circle a and the circle in the figure is the area between the circle and the wafer 2.
The amount of exposure is insufficient in the area sandwiched between the outer periphery and the outer periphery of the area. Also,
The position of the condensing lens 51 is controlled by the condensing lens moving means 56 so as to maintain a constant distance from the edge of the wafer 2 during continuous exposure, so that the exposure beam is not shaken due to a delay in control. This causes an area where the amount of exposure is insufficient to occur around the area to be exposed. As a result, as shown in FIG. 8, sagging occurs at the edge of the resist layer 7 formed on the wafer 2 after development.

Further, the wafer 2 is generally not a perfect circle, and has an error of about ±1 degree from the perfect circle. When exposure is performed using a conventional wafer peripheral exposure apparatus, the outer periphery of the resist layer remaining after development is not a perfect circle like the outer periphery of the wafer.

The purpose of the present invention is to eliminate these drawbacks,
When the resist layer formed on the wafer is removed from the peripheral area, 1! of the resist layer that remains remains! To provide a peripheral exposure device for a wafer, which prevents edges from sagging and makes the outer periphery a perfect circle.

[Means to solve the problem]

The above purpose is to provide a rotating means (11) for mounting a wafer (2) and for rotating this wafer (2), and
) in the X-axis direction, and a Y-axis moving means (13) to move the wafer (2) in the Y-axis direction.
), and a reference wafer is placed on the wafer stage (1) so that the center of the reference wafer coincides with the rotation axis center of the wafer stage (1). ! Y! at least three alignment sensors (31) provided at positions corresponding to the reference points on the outer periphery of the wafer when the wafer is placed;
wafer lifting means (4) for lifting and lowering the wafer (2) onto the wafer stage (1);
1), and an exposure light generating means (5) whose distance between the condensing lens (51) and the center of the wafer stage (L) can be adjusted; ) The shape of the exposure beam irradiated onto the wafer (2) from the condenser lens (51) is fan-shaped, and the curvature of the arc forming the fan-shape is approximately the same as the curvature of the wafer (2). It is distantly related to wafer peripheral exposure equipment.

[Effect]

When the wafer is placed on wafer stage 1 so that the center of the rotation axis of wafer stage L and the center of the wafer having the reference dimensions coincide, two points on the orientation flat selected as the peripheral reference points of the wafer and a circle An alignment sensor 31 is located at a position corresponding to one point on the circumference.
Since the wafer 2 is placed on the wafer stage 1 and moved, and aligned with the three alignment sensors 31, the wafer 2 is lifted using the wafer lifting means 4, and the wafer 2 is moved onto the wafer stage 1. When the wafer 2 is returned to the reference position before alignment and the wafer 2 is placed on the wafer stage 1 again, if the wafer 2 is formed according to the reference dimensions, the center of the rotation axis of the wafer stage 1 and the center of the wafer 2 are aligned. If the dimensions of the wafer 2 deviate from the reference dimensions, the corrected center of the wafer 2 is set at a position corresponding to the center of the rotation axis of the wafer stage 1.

In this state, as shown in FIG. 5, if the wafer 2 is sequentially exposed with the fan-shaped exposure beam 57 irradiated from the condenser lens 51 while rotating the wafer 2 once by the angle θ, the wafer 2
There is no area where the exposure amount is insufficient in the exposed area around the periphery of the resist layer 7, and therefore, as shown in FIG. 9, the edges of the resist layer 7 after development are less sagging. Further, the outer periphery of the resist layer remaining on the wafer 2 after development becomes a perfect circle centered on the corrected center of the wafer. In addition, wafer 2
When exposing the orientation flat part of
After rotating the condensing lens 51 using the condensing lens rotation means 52 so that the straight part of the fan-shaped exposure beam 57 is parallel to the orientation silane flat 21, as shown in FIG. The wafer stage 1 may be linearly moved parallel to the orientation flat 21 using the axis moving means 12 and the Y-axis moving means 13 for exposure.

〔Example〕

DESCRIPTION OF THE PREFERRED EMBODIMENTS A wafer peripheral exposure apparatus according to an embodiment of the present invention will be described below with reference to the drawings.

1a and 1b FIG. 1a is a plan view of a wafer peripheral exposure apparatus, and FIG. 1b is a side view.

In the figure, 1 is a wafer stage having a vacuum chuck on which a wafer 2 is placed, which is rotated by a rotating means 11, moved in the X-axis direction by an X-axis moving means 12, and moved in the Y-axis direction by a Yllll moving means 13. be done. Reference numeral 3 denotes an alignment unit, which aligns two points on the orientation flat of the wafer 2 when the wafer 2 having standard dimensions is placed on the wafer stage 1 so that its center coincides with the center of the rotating wheel of the wafer stage 1. A wafer alignment sensor 31 is provided at a position corresponding to one point on the circumference. 4 is wafer 2
This is a wafer elevating means that adsorbs the wafer and moves it up and down onto the wafer stage 1. 5 is an exposure light generating means, which includes a light source 55 such as a mercury lamp, an optical fiber 53, and a condensing lens 51 with a slit.
, a condensing lens rotation means 52 for rotating the condensing lens 51 , and a lens fixing table 54 for fixing the condensing lens 51 . are positioned to have predetermined dimensions corresponding to the size of the wafer 2.

See Figure 2. Figure 2 shows the shape of the exposure beam 57. Condensing lens 51
The exposure beam 57 is made into a fan shape using the slit , so that the curvature of the inner arc of the fan shape is approximately equal to the curvature of the wafer 2 .

See Figure 3 FIG. 3 shows the configuration of the alignment sensor 31.

The alignment sensor 31 consists of a light emitting element 3.11 made of a semiconductor laser and a light receiving element 312.
When the peripheral portion of the wafer 2 comes to the position of the alignment sensor 31, the light emitted by the light emitting element 311 is blocked by the wafer 2 and detected.

Refer to FIG. 4. The wafer 2 is placed on the wafer stage l, and moved using the rotation means 11, the X-axis moving means 12, and the Y-axis moving means 13, as shown in FIG. Positioning is performed so that two points on the orientation silane flat 21 and one point on the circumference correspond to the positions of the three alignment sensors 31 provided in the alignment unit 3, respectively.

The wafer 2 is sucked and lifted from the wafer stage 1 using the wafer lifting means 4, and after the wafer stage 1 is returned to the initial reference position, the wafer 2 is placed on the wafer stage 1 again.

As a result, the corrected center of the wafer 2 is set on the center of the rotating wheel of the wafer stage 1.

Refer to FIG. 5 As shown in FIG. 5, the wafer 2 is rotated by an angle θ around the corrected center using the rotating means 11, and fan-shaped exposure is irradiated from the condenser lens 51. Exposure is performed using the beam 57 in a stepwise manner.

When exposing the orientation flat portion 21 (see FIG. 6),
The condensing lens 51 is rotated using the condensing lens rotating means 52 so that the linear part of the fan-shaped exposure beam 57 becomes parallel to the orienting silane flat 21 as shown in FIG. 12 and Y-axis moving means 13 to linearly move the wafer stage 1 parallel to the orientation flat 21 for exposure.

〔Effect of the invention〕

As explained above, in the wafer peripheral exposure apparatus according to the present invention, the wafer is aligned on the wafer stage, and the corrected wafer center formed at the position corresponding to the rotation axis center of the wafer stage is used as the center.
Since step exposure is carried out on the same radius using a fan-shaped exposure beam, there is no blurring of the exposure beam and no areas with poor exposure amount occur in the exposed area, so there is extremely little drooping at the edges of the resist layer that remains after development. . Further, since exposure is performed using a fan-shaped exposure beam on the circumference centered on the corrected center, the outer circumference of the resist layer remaining after development becomes a perfect circle.

[Brief explanation of drawings]

FIG. 1a is a plan view of a wafer peripheral exposure apparatus according to an embodiment of the present invention. FIG. 1b is a side view of a wafer peripheral exposure apparatus according to an embodiment of the present invention. FIG. 2 is a diagram showing the shape of an exposure beam. FIG. 3 is an explanatory diagram of the alignment sensor. FIG. 4 is an explanatory diagram of wafer alignment. FIG. 5 is an explanatory diagram of the exposure method. FIG. 6 is an explanatory diagram of a method of exposing the orientation flat portion. FIG. 7 is a diagram illustrating the occurrence of underexposure areas in the prior art. FIG. 8 is a diagram showing droop at the edge of the resist. FIG. 9 is a diagram showing the shape of a resist edge when the wafer peripheral exposure apparatus according to the present invention is used. FIG. 10 is a plan view of a wafer peripheral exposure apparatus according to the prior art. FIG. 11 is a side view of a wafer peripheral exposure apparatus according to the prior art. 1 ・ ・ 11 ・ 12 ・ 13 ・ 2 ・ 21 ・ 3 ・ 31 ・ 311 ・ 312 ・ 4 ・ 5 ・ Wafer stage, rotation means, X-axis movement means, Y-axis movement means, Wafer, orientation unit, alignment sensor, light emitting element, light receiving element, wafer lifting means, exposure light generating means, 51. . 52. . 53. . 54. . 55. . 56. . 57・ ・ 6 ・ ・ 61・ ・ 62 Edge detection means, ・CCD line sensor, ・controller, ・residual resist.

Claims (1)

[Claims] A rotating means (11) for mounting a wafer (2) and rotating the wafer (2), an X-axis moving means (12) for moving the wafer (2) in the X-axis direction, and A wafer stage (1) having a Y-axis moving means (13) for moving the wafer (2) in the Y-axis direction, and a reference wafer placed on the wafer stage (1) so that the center of the reference wafer is The wafer stage (
At least three alignment sensors (31) provided at positions corresponding to the outer periphery reference point of the reference wafer when placed so as to coincide with the rotation axis center of 1).
an alignment unit (3) having: a wafer elevating means (4) for elevating the wafer (2) onto and lowering the wafer stage (1); and a rotatable condensing lens (51), the condensing lens (51) and an exposure light generating means (5) whose distance from the center of the wafer stage (1) is adjustable, and the condenser lens (51) of the exposure light generating means (5) (2) A wafer peripheral exposure apparatus characterized in that the shape of the exposure beam irradiated onto the wafer (2) is fan-shaped, and the curvature of the arc forming the fan-shape is approximately the same as the curvature of the wafer (2).