JP2835746B2 - Wafer peripheral exposure equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Summary] The present invention relates to a wafer peripheral exposure apparatus used for removing a resist layer formed on a wafer from a peripheral region of the wafer, and a resist layer formed on the wafer from the peripheral region. An object of the present invention is to provide a peripheral exposure apparatus for a wafer in which the edge of the remaining resist layer does not sag when removed, and the outer periphery is a perfect circle. A wafer stage having a rotating means for rotating the wafer, a Χ axis moving means for moving the wafer in the Χ axis direction, and a Y axis moving means for moving the wafer in the Y axis direction, and a wafer serving as a reference on the wafer stage. When the wafer is mounted such that the center of the reference wafer coincides with the center of the rotation axis of the wafer stage, the outer peripheral base of the reference wafer An alignment unit having at least three alignment sensors provided at positions corresponding to points, a wafer elevating means for elevating the wafer on the wafer stage, and a rotatable condenser lens; The distance between the condensing lens and the center of the wafer stage has an exposure light generating means that can be adjusted, and the shape of the exposure beam irradiated on the wafer from the condensing lens of the exposure light generating means is It comprises a wafer peripheral exposure device which is sector-shaped and the curvature of the sector-shaped arc is approximately the same as the curvature of the wafer.

[Industrial applications]

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

[Conventional technology]

In a semiconductor device manufacturing process, a photolithography process is required in which a resist layer is formed on a wafer and exposed and developed using a mask to form a resist pattern. If the layer is not removed, the resist will come into contact with the carrier grooves when the wafer is placed in the carrier,
May cause dusting. The wafer periphery exposure apparatus is an apparatus that exposes the periphery of a wafer to remove a resist layer around the wafer.

FIG. 10 and FIG.
This will be described with reference to FIG. FIG. 10 is a plan view and FIG.
The figure is a side view. In the figure, reference numeral 1 denotes a wafer stage having a vacuum chuck on which a wafer 2 is placed, and is rotated by a rotation unit 11. Exposure light generation means 5 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 square exposure beam and irradiate the wafer 2 with the light. The distance of the condenser lens 51 from the center of the wafer stage 1 is controlled by the condenser lens moving means 56. Reference numeral 6 denotes a wafer edge detecting means, which comprises a CCD line sensor 61 and a controller 62 which processes this signal and stores the position of the wafer edge.

The wafer 2 is placed on the wafer stage 1, and the edge of the wafer 2 is subjected to the CCD while rotating using the rotating means 11.
The signal is detected by the line sensor 61, the signal is image-processed in the controller 62, the position of the edge of the wafer is stored, and based on the stored position information of the edge of the wafer, the focusing lens moving means 56 is moved. Control and condenser lens 51
Is aligned with the periphery of the wafer 2, and a region having a certain width from the edge of the wafer 2 is exposed.

[Problems to be solved by the invention]

By the way, when the wafer 2 is rotated while irradiating the peripheral area of the wafer 2 with the rectangular exposure beam 57, the seventh
The area between the circles a and b in the figure is the circle b and the wafer 2
The exposure amount is smaller than the region sandwiched between the outer periphery of the lens. Also,
Since the position of the condenser lens 51 is continuously exposed while being controlled by the condenser lens moving means 56 so as to keep a constant distance from the edge of the wafer 2, the exposure beam is blurred due to control delay. As a result, a region with an insufficient amount of exposure occurs around the region to be exposed. As a result, as shown in FIG. 8, dripping occurs at the edge of the resist layer 7 formed on the wafer 2 after the development.

In addition, the wafer 2 generally does not form a perfect circle, and ± 1 m
There is an error from a perfect circle about m. When exposure is performed using a conventional wafer peripheral exposure apparatus, the outer periphery of the resist layer remaining after development does not become a perfect circle like the outer periphery of the wafer.

An object of the present invention is to eliminate these drawbacks. When the resist layer formed on the wafer is removed from the peripheral region, the edge of the remaining resist layer does not drop, and the outer periphery is reduced. It is an object of the present invention to provide a peripheral exposure apparatus for a wafer so as to have a perfect circle.

[Means for solving the problem]

The above object is to place the wafer (2), rotate the wafer (2), rotate the wafer (2), move the wafer (2) in the axial direction, and move the wafer (2) in the axial direction. Y-axis moving means (1) for moving (2) in the Y-axis direction
3) a wafer stage (1) having a reference wafer on the wafer stage (1);
An alignment unit (3) having at least three alignment sensors (31) provided at positions corresponding to the outer circumferential reference point of the wafer serving as the reference when mounted so as to coincide with the center of the rotation axis A wafer elevating means (4) for elevating the wafer (2) on the wafer stage (1), and a rotatable condenser lens (51)
And an exposure light generating means (5) whose distance between the condenser lens (51) and the center of the wafer stage (1) is adjustable. The shape of the exposure beam emitted from the condenser lens (51) onto the wafer (2) is a sector, and the curvature of the arc forming the sector is substantially the same as the curvature of the wafer (2). This is achieved by a peripheral exposure device.

[Action]

When the wafer is placed on the wafer stage 1 such that the center of the rotation axis of the wafer stage 1 and the center of the wafer having the reference dimension coincide, two points and a circle on the orientation flat selected as peripheral reference points of the wafer. The alignment sensor 31 is located at a position corresponding to one point on the circumference.
Is provided, the wafer 2 is placed on the wafer stage 1 and moved, and the wafer 2 is lifted using the wafer elevating means 4 after being positioned with the three alignment sensors 31. Is returned to the reference position before the alignment, and the wafer 2 is again moved to the wafer stage 1.
When mounted on the upper surface, if the wafer 2 is formed according to the reference size, the center of the rotation axis of the wafer stage 1 coincides with the center of the wafer 2, and the size of the wafer 2 is shifted from the reference size. In case, wafer stage 1
The corrected center of the wafer 2 is set at a position corresponding to the center of the rotation axis.

In this state, as shown in FIG.
By successively exposing with the fan-shaped exposure beam 57 emitted from the condenser lens 51 while rotating, an area with insufficient exposure does not occur in the exposure area around the wafer 2,
Therefore, as shown in FIG.
The edge of the edge is less drooping. Further, the outer periphery of the resist layer remaining on the wafer 2 after the development is a perfect circle centered on the corrected center of the wafer. When the orientation flat portion of the wafer 2 is exposed, the condenser lens 51 is rotated using the condenser lens rotating means 52,
As shown in FIG. 6, after the linear portion of the fan-shaped exposure beam 57 is made parallel to the orientation flat 21, the wafer stage 1 is oriented using the Χ-axis moving means 12 and the Y-axis moving means 13. The exposure may be performed by linearly moving the flat 21 in parallel.

〔Example〕

Hereinafter, a wafer peripheral exposure apparatus according to an embodiment of the present invention will be described with reference to the drawings. Fig. 1a, 1b
FIG. 1a is a plan view of a wafer peripheral exposure apparatus,
FIG. 1b is a side view.

In the drawing, reference numeral 1 denotes a wafer stage having a vacuum chuck on which a wafer 2 is placed, which is rotated by a rotating means 11, moved in a Χ-axis direction by a Χ-axis moving means 12, and moved in a Y-axis direction by a Y-axis moving means 13. Be moved. 3
Is an alignment unit, which is a circle having two points on an orientation flat of the wafer 2 when the wafer 2 having a reference dimension is placed on the wafer stage 1 so that the center thereof coincides with the center of the rotation axis of the wafer stage 1. A wafer alignment sensor 31 is provided at a position corresponding to one point on the circumference. Reference numeral 4 denotes a wafer lifting / lowering unit that attracts the wafer 2 and moves up and down on the wafer stage 1. Reference numeral 5 denotes an exposure light generating means, which includes a light source 55 such as a mercury lamp, an optical fiber 53, a condensing lens 51 with a slit, a condensing lens rotating means 52 for rotating the condensing lens 51, and a lens fixing base for fixing the condensing lens 51. The distance between the center of the rotation axis of the wafer stage 1 and the condenser lens 51 is
The wafer 2 is positioned so as to have a predetermined size corresponding to the size of the wafer 2.

See FIG. 2. FIG. 2 shows the shape of the exposure beam 57. The slit of the condenser lens 51 is used to form the exposure beam 57 into a sector shape so that the curvature of the sector arc is approximately equal to the curvature of the wafer 2.

See FIG. 3. FIG. 3 shows the configuration of the alignment sensor 31. The alignment sensor 31 is a light emitting element 31 composed of a semiconductor laser.
1 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 emitting element 31
One emitted light is detected by being shielded by the wafer 2.

Referring to FIG. 4, the wafer 2 is placed on the wafer stage 1 and moved using the rotating means 11, the Χ-axis moving means 12, and the Y-axis moving means 13, and as shown in FIG. Positioning is performed so that two points on the orientation flat 21 and one point on the circumference correspond to the positions of three alignment sensors 31 provided in the alignment unit 3 respectively.

The wafer 2 is sucked and lifted from the wafer stage 1 by using the wafer elevating means 4,
Is returned to the initial reference position, and the wafer 2 is mounted on the wafer stage 1 again. As a result, the corrected center of the wafer 2 is set on the center of the rotation axis of the wafer stage 1.

Referring to FIG. 5, as shown in FIG. 5, a sector-shaped exposure radiated from the condenser lens 51 while rotating the wafer 2 by an angle θ around the corrected center using the rotating means 11. Exposure is performed stepwise with the beam 57.

See FIG. 6. When exposing the orientation flat part 21,
The condensing lens 51 is rotated using the condensing lens rotating means 52 so that the linear portion of the fan-shaped exposure beam 57 is parallel to the orientation flat 21 as shown in FIG. The wafer stage 1 is linearly moved in parallel with the orientation flat 21 using the Y-axis moving means 13 and the exposure.

〔The invention's effect〕

As described above, in the wafer peripheral exposure apparatus according to the present invention, the wafer is positioned on the wafer stage, and the corrected wafer center formed at a position corresponding to the rotation axis center of the wafer stage is centered. Since step exposure is performed on the same radius with a fan-shaped exposure beam, there is no blurring of the exposure beam, and there is no defective area in the exposure area, so that dripping of the edge of the resist layer remaining after development is extremely small. . Further, since the exposure is performed with a fan-shaped exposure beam on the circumference with the corrected center as the center, the outer circumference of the resist layer remaining after development becomes a perfect circle.

[Brief description of the drawings]

FIG. 1a is a plan view of a wafer peripheral exposure apparatus according to one embodiment of the present invention. FIG. 1b is a side view of a wafer peripheral exposure apparatus according to one embodiment of the present invention. FIG. 2 is a view showing the shape of an exposure beam. FIG. 3 is an explanatory diagram of an alignment sensor. FIG. 4 is an explanatory diagram of wafer positioning. 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 for explaining the occurrence of an underexposure amount region in the related art. FIG. 8 is a diagram showing the drooping of the edge of the resist. FIG. 9 is a view 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 peripheral exposure apparatus for a wafer according to the prior art. DESCRIPTION OF SYMBOLS 1 ... Wafer stage, 11 ... Rotating means, 12 ... Axis moving means, 13 ... Y-axis moving means, 2 ... Wafer, 21 ... Orientation flat, 3 ... Alignment unit, 31 ... Alignment Sensor, 311 light emitting element, 312 light receiving element, 4 wafer elevating means, 5 exposure light generating means, 51 condensing lens, 52 condensing lens rotating means, 53 fiber 54: Lens fixing stand, 55: Light source, 56: Condensing lens moving means, 57: Exposure beam, 6: Wafer edge detection means, 61: CCD line sensor, 62: Controller, 7 ...... Remaining resist.

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁶ , DB name) H01L 21/027

Claims (1)

(57) [Claims] 1. A wafer (2) is mounted thereon, a rotating means (11) for rotating the wafer (2), an X-axis moving means (12) for moving the wafer (2) in the Χ-axis direction, and the wafer (2) a wafer stage (1) having a Y-axis moving means (13) for moving the wafer in the Y-axis direction; and a wafer serving as a reference on the wafer stage (1). At least three alignment sensors (31) provided at positions corresponding to the outer peripheral reference point of the reference wafer when mounted so as to coincide with the center of the rotation axis of the wafer stage (1).
An alignment unit (3) having: a wafer elevating means (4) for elevating and lowering the wafer (2) on the wafer stage (1); and a rotatable condenser lens (51). An exposure light generating means (5) whose distance between the (51) and the center of the wafer stage (1) is adjustable; (2) A peripheral exposure apparatus for a wafer, wherein the shape of the exposure beam irradiated on the wafer has a sector shape, and the curvature of the arc forming the sector is substantially the same as the curvature of the wafer (2).