JP3172085B2 - Peripheral exposure equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a peripheral exposure apparatus for exposing a peripheral portion of a circular substrate such as a wafer coated with a resist for manufacturing semiconductor devices.

[0002]

2. Description of the Related Art In a lithography process of manufacturing a semiconductor device, it is known that when a resist applied to a wafer for forming a circuit remains on a peripheral portion of the wafer, the resist is peeled off by transportation or the like and causes a device defect. In order to prevent this, various methods have been proposed for exposing the resist on the peripheral portion of the wafer and removing the resist in a developing step. For example, in Japanese Patent Application Laid-Open Nos. 2-114628 and 2-101734, the peripheral portion of the wafer has a substantially constant width by moving the exposure light irradiator in the radial direction of the wafer while rotating the wafer about its center. A method of exposing is proposed.

These devices include holding and rotating means for attracting and rotating the center of a wafer, illumination means for exposing the peripheral edge of the wafer, and radial displacement of the peripheral edge of the wafer caused by eccentricity of the wafer and orientation flat as the wafer rotates. It is basically composed of a periphery detecting means for detecting, and a moving means for relatively moving the rotating means and the lighting means.

[0004]

However, in the prior art, the effect of the increase in defocus amount at the peripheral portion of the wafer caused by the lamination of elements and the enlargement of the wafer size due to the high integration of ICs, which will be advanced in the future, will be discussed. Not fully considered.

That is, the variation in the amount of warpage due to the difference in the wafer processing process and the whirling of the holding and rotating means deteriorate the detection accuracy of the peripheral edge, the accuracy of the exposure width, the shift of the exposure focus, and the distribution of the light amount at the boundary of the exposure region. Invites a slowdown. In particular, the latter has a possibility that the slope of the incompletely removed portion (gray zone) of the resist is made gentle, and the resist at the time of dropout is separated into islands under the influence of unevenness during development. Then, in the wet etching process of the multilayer film, these are peeled and floated as island-like films, and adhere to the circuit portion to cause defects, thereby causing a problem that the yield is deteriorated.

SUMMARY OF THE INVENTION In view of the above-mentioned problems of the prior art, an object of the present invention is to prevent a peripheral exposure apparatus from deteriorating the edge detection accuracy and defocusing due to fluctuations in the height of the peripheral edge due to wafer warpage and whirling. Is to provide.

[0007]

In order to achieve the above object, according to the present invention, there is provided a rotating means for rotating a substrate on which a resist is applied substantially uniformly, about a substantially center thereof.
When, a light irradiating means for irradiating the exposure light to the peripheral portion of the substrate
In the peripheral exposure apparatus provided with, the substrate by the rotating means
A distance measuring means for detecting a relative distance between the light irradiating means and a resist coating surface at a peripheral portion of the substrate while rotating the light irradiating means; and a focus of the light irradiating means based on an output of the distance measuring means. And a focus correction unit that corrects

In a preferred embodiment of the present invention, the focus correcting means converts an output of the distance measuring means into a projection optical system object plane displacement amount of the light irradiating means,
Object plane moving means for displacing the object plane of the light irradiation means based on the output from the arithmetic means. Alternatively, it is characterized by comprising moving means for relatively moving the substrate and the light irradiating means so as to keep the output of the distance measuring means within a predetermined range.

According to another aspect of the present invention, there is provided an apparatus for exposing a peripheral portion of a substrate on which a resist is applied substantially uniformly while rotating the substrate around a substantially center thereof. Peripheral detecting means for detecting a radial displacement of the rotating means;
The light irradiation means and the periphery of the substrate are rotated while rotating the substrate.
A distance measuring means for detecting a relative distance between the resist coating surface of the edge and a Z moving means for vertically displacing the wafer based on an output of the distance measuring means; When detecting, the Z-moving means is servo-controlled so that the output of the distance-measuring means is kept within a predetermined range, and when exposing, the Z-moving means is controlled based on the servo amount.

[0010]

According to the present invention, the light irradiating means is disposed near the light irradiating means for irradiating the peripheral edge of the substrate coated with the resist substantially uniformly with the exposure light, and the rotating means rotates the substrate. A distance measuring means for detecting a relative distance between a resist coating surface of a peripheral portion of the substrate and a focus correcting means for correcting a focus of the light irradiating means based on an output of the distance measuring means; The amount of deviation between the focus surface and the resist-coated surface of the substrate can be kept within a predetermined range, and deterioration of exposure width accuracy due to warpage or whirling of the substrate and expansion of a gray zone can be prevented.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a configuration of a peripheral exposure apparatus according to an embodiment of the present invention.
Is a side view showing a. In FIG. 1, reference numeral 1 denotes a wafer on which a resist is applied substantially uniformly. The peripheral exposure apparatus shown in FIG. 1 is provided with an illuminating means 7 for exposing the peripheral portion of the resist coating surface of the wafer 1, and is disposed in the vicinity of the illuminating means, and is displaced in a direction perpendicular to the same exposed surface of the wafer 1 (that is, The length measuring means 8 for detecting the relative distance between the illuminating means 7 and the resist-coated surface of the wafer 1 is connected to a vacuum pipe (not shown), and the vacuum pressure holds the wafer 1 substantially at the center. Holding rotating stage (hereinafter, rotating table) 2 to rotate
A Z stage 3 for moving the turntable 2 up and down;
An XZθ stage comprising a stage 3 which is linearly moved in a direction intersecting a horizontal plane with a plane including the optical axis of the illumination means 7 and the rotation center axis of the turntable 2, and a wafer from the turntable rotation axis. A peripheral edge detecting means 6 which is offset by one radius and is arranged at a predetermined position from the illumination means 7 and detects a radial displacement of the peripheral edge of the wafer caused by the rotation of the wafer. The base of each of these members is fixed to the base 5.

An output from the XZθ control unit 10 for controlling the amount of movement of the XZθ stage and the outputs from the length measuring means 8 and the peripheral edge detecting means 6 in relation to the rotation angle of the wafer 1 are stored. A control amount of the XZθ axis is calculated so as to keep the irradiated surface and the focus surface of the illuminating means 7 constant, and keep the width of the peripheral edge of the wafer illuminated by the illuminating means 7 constant. It also has a calculation unit 9.

According to the present embodiment, the relative distance between the illuminating means 7 and the resist-coated surface of the wafer 1 is located near the illuminating means 7 for irradiating the peripheral edge of the wafer 1 on which the resist is substantially uniformly applied with exposure light. Is arranged and the Z stage 3 is moved up and down based on the output of the length measuring means 8 to correct the focus of the illuminating means 7. Can be kept within a predetermined range, and it is possible to prevent the exposure width accuracy from deteriorating due to the warpage and whirling of the wafer 1 and prevent the gray zone from expanding.

FIG. 2 is a side view showing the configuration of a peripheral exposure apparatus according to a second embodiment of the present invention. This peripheral exposure apparatus is connected to an illuminating means 17 for exposing the peripheral portion of the wafer and a vacuum pipe (not shown), and holds a substantially center of the wafer 11 by the vacuum pressure, and a holding and rotating stage (hereinafter, referred to as a rotating stage) for rotating the wafer 11. A turntable 12, a Z stage 13 that moves the turntable 12 up and down, and an intersection of a horizontal plane with a plane including the optical axis of the illumination unit 17 and the rotation center axis of the turntable 12. X stage 14 that moves in the direction
An XZθ stage , a peripheral edge detecting means which is offset from the rotary shaft rotation axis by a radius of the wafer 11 and is disposed at a predetermined position from the illumination means 17 and detects a radial displacement of a peripheral edge of the wafer caused by the rotation of the wafer 11 16 and a length measuring means 18 disposed near the periphery detecting means for detecting a displacement of the exposure surface of the wafer 11 in a direction perpendicular to the same, and these bases are fixed to the base 15. ing.

An output from the length measuring means 18 and the periphery detecting means 16 is stored in association with an XZθ control unit 20 for controlling the amount of movement of the XZθ stage, and a rotation angle of the wafer 11. A storage operation unit that calculates a control amount of the XZθ axis so as to keep the irradiated surface and the focus surface of the illumination unit 17 constant and also keeps the width of the peripheral edge of the wafer illuminated by the illumination unit constant, and supplies the control amount to the XZθ control unit 20 19 as well.

The peripheral exposure apparatus shown in FIG. 2 is characterized in that the length measuring means 8 is arranged near the illumination means 7 in FIG. 1, whereas the length measuring means 18 is arranged near the periphery detecting means 16. And In the present embodiment, first, the Z stage 13 is controlled by the output of the length measuring means 18 so that the height of the resist coating surface of the wafer 11 becomes constant while the turntable 2 holding the wafer 11 is rotated. The peripheral edge of the wafer 11 is detected by the peripheral edge detecting means 16 while the servo amount and the wafer peripheral position at that time are stored in the storage operation unit 19. Next, based on these stored amounts, the height and the peripheral position of the wafer are fixed at the position of the illumination means 17,
While controlling the Z stage 13 and the X stage 14 , light is emitted from the illumination means 17 to expose the wafer periphery. According to the present embodiment, since the wafer height is kept constant at the time of detecting the peripheral edge, the peripheral position can be detected with higher accuracy, and the exposure width accuracy is deteriorated due to the warpage or whirling of the wafer 11 and the gray zone is reduced. Can be prevented from expanding.

[0017]

As described above, according to the present invention, it is possible to prevent the deterioration of the edge position detection accuracy and the exposure defocus caused by the warpage of the processed wafer and the whirling of the wafer rotating shaft.

[Brief description of the drawings]

FIG. 1 is a side view showing a configuration of a peripheral exposure apparatus according to one embodiment of the present invention.

FIG. 2 is a side view showing a configuration of a peripheral exposure apparatus according to a second embodiment of the present invention.

[Explanation of symbols]

1, 11: wafer, 2, 12: rotary stage (rotary table), 3, 13: Z stage, 4, 14: X stage ,
5, 15: base, 6, 16: periphery detecting means, 7, 17:
Illuminating means, 8, 18: length measuring means, 9, 19: storage operation section, 10, 20: XZθ control section .

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-9-97761 (JP, A) JP-A-63-111616 (JP, A) JP-A-4-209516 (JP, A) JP-A-4- 71217 (JP, A) JP-A-3-218619 (JP, A) JP-A-1-295421 (JP, A) JP-A-5-217887 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H01L 21/027

Claims (4)

(57) [Claims] A rotating means for rotating the substrate about a center of the substrate on which the resist is applied substantially uniformly;
In peripheral exposure apparatus equipped with a light irradiating means for irradiating the exposure light to the peripheral portion of the substrate, the resist coating surface of the peripheral portion of the light irradiation unit and the substrate while rotating the substrate by the rotating means a distance measuring means for detecting the relative distance, peripheral exposure device substrate; and a focus correcting means for correcting the focus of the light irradiation means based on an output of the distance measuring means. 2. The focus correcting means includes a calculating means for converting an output of the distance measuring means into a displacement amount of an object plane of a projection optical system of the light irradiating means, and the light irradiating means based on an output from the calculating means. peripheral exposure apparatus according to claim 1, characterized in that it consists of an object plane moving means for displacing the object plane of the. 3. The apparatus according to claim 1, wherein said focus correcting means comprises a moving means for relatively moving said substrate and said light irradiating means so as to keep an output of said distance measuring means within a predetermined range. peripheral exposure device. 4. A rotating means for rotating the substrate about a substantially center of the substrate on which the resist is applied substantially uniformly,
In peripheral exposure apparatus equipped with a light irradiating means for irradiating the exposure light to the peripheral portion of the substrate, and the peripheral detecting means for detecting a radial displacement of the peripheral portion of the substrate, it is disposed in the vicinity of the peripheral edge detecting means The rotation means
A distance measuring means for detecting a relative distance between the light irradiating means and a resist coating surface at a peripheral portion of the substrate while rotating the plate ; and a vertical direction relative to the wafer based on an output of the distance measuring means. A Z-moving means for giving a displacement; a servo-controlling means for controlling the Z-moving means so as to keep an output of the distance-measuring means within a predetermined range when detecting the radial direction of the periphery of the wafer; peripheral exposure device substrate; and a control means for controlling the Z moving unit Te.