JPH09293675A - Peripheral exposure device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize a peripheral exposure device which can expose the peripheral part of the photosensitive surface of a substrate with exposure light of the optimum amount of irradiation. SOLUTION: This device is a device of a structure, wherein exposure light is irradiated on the peripheral part of the photosensitive surface 11AX of a substrate 11A to be exposed, which is formed, by coating a photosensitive material 11B on this photosensitive surface, whereby the peripheral part of the surface 11AX of the substrate 11A is exposed. In the case, this device is constituted so as to provide an illuminance variably means 17, which changes the illuminance of the exposure light, which irradiates the peripheral part of the surface 11AX of the substrate 11A, in the direction to turn from the inside of the surface 11AX is the substrate 11A to the outside of the surface 11AX, whereby the illuminance of the exposure light, which irradiates the peripheral part of the surface 11AX of the substrate 11A, can be changed according to the film thickness of the material 11B. Thus, the peripheral aligner 10 which can expore the peripheral part of the surface 11AX of the substrate 11A with the exposure light of the optimum amount of irradiation, can be realized.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an edge exposure apparatus, and is suitable for application to an edge exposure apparatus for exposing a peripheral portion such as a semiconductor wafer or a photomask glass substrate.

[0002]

2. Description of the Related Art Conventionally, for example, as one step for forming a fine pattern such as a semiconductor integrated circuit on one surface of a wafer,
There is a step of forming a resist layer made of a resist patterned into a desired fine pattern on one surface of the wafer. In this case, in this step, usually, a photosensitive resist is uniformly coated on one surface of the wafer, dried, and then
The resist is patterned by exposing and developing the resist using a mask corresponding to a desired fine pattern.

By the way, in such a process, the resist applied to the peripheral portion of the wafer is easily peeled off at the time of positioning and chucking in various processing steps, and the peeled resist becomes dust and adheres to the wafer, and the fine particles thereafter. There is a problem that the pattern forming process is adversely affected. Therefore, conventionally, before exposing the resist on the wafer according to a desired fine pattern, a dedicated device called a peripheral exposure device is used in advance so that the resist on the peripheral portion of the wafer is removed during development. Had exposed the resist.

Here, in the conventional peripheral exposure apparatus,
By rotating the wafer while irradiating the resist on the peripheral portion of the wafer with exposure light with a constant illuminance, the resist on the peripheral portion of the wafer can be exposed with a constant exposure width. Specifically, the wafer is rotated at a constant speed while controlling the relative position between the wafer and the emitting portion while keeping the distance between the emitting portion for emitting the exposure light and the peripheral portion of the wafer constant. The resist applied to the peripheral portion was exposed by irradiating the resist with exposure light.

[0005]

By the way, conventionally, a negative type resist has been the main force used as a resist in the step of forming a fine pattern as described above. However, in recent years, a positive resist has been widely used as a resist in place of a negative resist in an exposure process using an exposure method called a step-and-repeat method that exhibits high resolution.

This positive resist has a characteristic that it is decomposed by irradiation of light and becomes soluble in a developing solution, and only the exposed portion is dissolved and removed by a developing treatment. FIG. 7 shows the ratio of the residual film thickness after development to the irradiation light amount of such a positive resist (given by the product of the illuminance of the exposure light and the irradiation time), and the curve K2 is the curve K1.
On the other hand, the irradiation characteristic curve when the film thickness of the resist applied to the wafer is thin is shown, and the curve K3 shows the characteristic curve when the film thickness of the resist applied to the wafer is thicker than the curve K1.

By the way, as shown in FIG. 8, in the positive type resist 2, a portion corresponding to the outside of the peripheral portion of the wafer 1 is usually raised in a state where it is applied to the wafer 1.
Therefore, when the peripheral exposure process of the wafer 1 in which the positive type is used as the resist 2 is performed by using the conventional peripheral exposure apparatus, the film of the resist 2 inside the peripheral portion of the wafer 1 having a substantially constant film thickness. When the irradiation amount of the exposure light is set to an optimum value corresponding to the thickness, there is a problem that the resist 2 on the outer periphery of the wafer 1 is overexposed.

In such a case, this resist 2 is used during development.
The under-exposed portion was not completely removed, and as a result, the resist 2 remained on the peripheral portion of the wafer 1 after development, which caused the above-mentioned dust. On the other hand, if the optimum irradiation amount of the exposure light is set so as to correspond to the film thickness of the resist 2 on the outer side of the peripheral portion of the wafer 1, the resist 2 on the inner side of the peripheral portion of the wafer 1 is overexposed and a predetermined exposure width is set. There is a problem that the exposure profile (FIG. 9) is deteriorated, for example, the exposure region to be formed with a width becomes wider.

When the resist 2 on the peripheral portion of the wafer 1 is overexposed as described above, light is reflected inside the resist 2 at the boundary between the resist 2 and the wafer 1, and the light is re-incident on the resist 2 again. As a result, the resist 2 is exposed to light, so-called harration may occur. In such a case, bleeding may occur in the exposure light or firing may occur in the resist 2 as disclosed in JP-A-2-12811. As a result, the wafer surrounded by diagonal lines in FIG. There is also a problem that the area in which the first fine pattern is formed (hereinafter, referred to as a fine pattern formation area) becomes small, leading to a decrease in yield.

Further, when the optimum irradiation amount of the exposure light is set corresponding to the film thickness of the resist 2 on the outer periphery of the wafer 1, it is necessary to increase the irradiation time of the exposure light on the wafer 1. There is also a problem that it requires a lot of processing time. Therefore, for example, if the resist 2 applied to the wafer 1 can be exposed to the optimum amount of light irrespective of the inside and outside of the wafer 1, generation of dust, deterioration of the exposure profile, decrease in yield, and increase in processing time. It is considered that such problems can be avoided, and the productivity of products such as chips manufactured through the fine pattern forming process can be significantly improved.

The present invention has been made in consideration of the above points, and it is an object of the present invention to propose a peripheral exposure apparatus that can always expose the peripheral portion of the photosensitive surface of the substrate to be exposed with the optimum amount of exposure light. is there.

[0012]

In order to solve such a problem, in the present invention, the exposure light (L1) is applied to the peripheral portion of the photosensitive surface of a substrate (12) to be exposed having a photosensitive material (11B) coated on the photosensitive surface. ), The exposed substrate (1
2) In the peripheral exposure device that exposes the peripheral portion of the photosensitive surface, the illuminance of the exposure light (L1) that irradiates the peripheral portion of the photosensitive surface of the exposed substrate (12) to the photosensitive surface of the exposed substrate (12). An illuminance varying means (17) for changing the direction from the inner side to the outer side is provided.

As a result, the peripheral portion of the photosensitive surface of the exposed substrate (12) can be changed according to the film thickness of the photosensitive material (11B).

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below in detail with reference to the drawings.

In FIG. 1, reference numeral 10 denotes a peripheral exposure apparatus according to the embodiment as a whole, and one surface 11AX of a wafer 11A.
The substrate 12 coated with the positive resist 11B is adsorbed and held by the substrate chuck section 13, and is rotated based on the rotational force applied to the substrate chuck section 13 from the substrate driving section 14.

At this time, the rotation state of the substrate 12 is detected by the encoder 15 via the substrate driving unit 14 and is supplied to the control unit 16 as a rotation position information signal S1. The control unit 16 also controls the control signal S based on the rotational position information signal S1.
2 is generated and sent to the substrate driving unit 14 so that the substrate 12 rotates at a constant speed.
Drive control.

On the other hand, in the vicinity of the substrate chuck section 13, an illuminance varying section 17 and a light receiving section 18 are integrally formed by a holder 19,
Further, a peripheral exposure unit 20 which is held so as to face each other via the peripheral portion of the substrate 12 is movably arranged in the radial direction (arrow a) of the substrate 12. In this case, the exposure light emitted from the light source unit 21 is sequentially applied to the illuminance varying unit 17 through the ride guide 22, the shutter 23, and the ride guide 24. The illuminance varying unit 17 changes the illuminance distribution of the exposure light in the radial direction of the substrate 12, and then emits the illuminance distribution toward the light receiving unit 18.

As a result, in the peripheral exposure apparatus 10,
The exposure light L1 emitted from the illuminance varying unit 17 can be applied to the peripheral portion of the substrate 12, and thus the peripheral portion of the substrate 12 can be exposed by the exposure light L1. At this time, the light receiving section 18 is configured to expose the exposure light L that has passed through the peripheral edge of the substrate 12.
1 is received, and a light reception signal S having a signal level corresponding to the light amount is received.
3 is sent to the control unit 16. Further, the control unit 16 generates the control signal S4 based on the light receiving signal S3 and sends it to the peripheral exposure unit driving unit 25, so that the light receiving unit 1
The peripheral exposure unit drive unit 25 is driven and controlled so that the peripheral exposure unit 20 is moved in the radial direction of the substrate 12 as necessary so that the exposure light L1 of a constant light amount is incident on 8.

As a result, in this peripheral exposure apparatus 10, the amount of the exposure light L1 incident on the light receiving portion 18 of the peripheral exposure unit 20 can be made constant, and therefore the amount of the exposure light L1 incident on the peripheral portion of the substrate 12 is increased. The amount of light (incident width) can be made constant, and thus the peripheral portion of the substrate 12 can be exposed with a constant exposure width.

Here, in the case of this embodiment, the illuminance varying section 17
Is an ND filter 3 made of a glass material having a uniform concentration in the thickness direction, which is formed so that the thickness gradually decreases toward the outside of the peripheral portion of the substrate 12 as shown in FIG.
0. As a result, in the illuminance varying section 17, the illuminance of the transmitted exposure light L1 can be changed so as to increase toward the outside of the peripheral portion of the substrate 12, as indicated by the solid line K10 in FIG. There is.

In this case, the thickness of each part of the ND filter 30 is selected so that the illuminance of the transmitted exposure light L1 is optimum at each position on the peripheral portion of the substrate 12.
In practice, such illuminance can be calculated from the resist film thickness at each position on the substrate 12 which is measured or estimated in advance, using the irradiation characteristic curves K1 to K3 of the positive resist of FIG. As a result, in the peripheral exposure apparatus 10, the peripheral portion of the substrate 12 can be exposed with the exposure light L1 having the optimum illuminance at each position of the peripheral portion of the substrate 12.

In the above-mentioned structure, this peripheral exposure apparatus 1
0, during operation, the substrate 12 to be exposed is attracted and held by the substrate chuck 13 and rotated while the light source 21 is rotated.
The exposure light emitted from the illuminance distribution unit 1 calculates the illuminance distribution of the exposure light.
In step 7, the illuminance is changed so as to increase toward the outer peripheral portion of the substrate 12, and then the peripheral portion of the substrate 12 is exposed by irradiating the peripheral portion of the substrate 12.

Therefore, in the peripheral exposure apparatus 10, since the peripheral portion of the substrate 12 in which the film thickness of the resist 11B increases toward the outside can be exposed by the exposure light L1 having a higher illuminance toward the outside, the substrate is exposed. The peripheral portion of 12 can be exposed with the exposure light L1 having the optimum illuminance over the entire area in the radial direction. Therefore, in this peripheral exposure apparatus 10, the resist 11B on the peripheral portion of the substrate 12 can be exposed over the entire surface in the radial direction without producing an unexposed portion. Therefore, after development, the resist on the peripheral portion of the substrate 12 can be exposed. 11B can be completely removed from the wafer 11A, and the dust of the resist 11B can be reliably prevented from being generated from the peripheral portion of the substrate 12 in various steps following the developing step.

Further, in the peripheral exposure apparatus 10, since the resist 11B on the peripheral portion of the substrate 12 can be completely removed after the development, a fine pattern forming region composed of the peripheral portion of the substrate 12 and the inner peripheral portion of the substrate 12 is formed. The position dimension of the boundary line between and can be increased. Therefore, since a predetermined number of fine patterns (circuit patterns) can be formed in the fine pattern forming region of the substrate 12 without deterioration of the exposure profile, the chip yield can be improved.

Further, in this peripheral exposure apparatus 10, the substrate 1
Since the peripheral portion of 2 can be exposed with the exposure light L1 having the optimum illuminance over the entire area regardless of the inner peripheral side and the outer peripheral side, the processing can be performed only at a higher rotation speed. Minute throughput (number of sheets processed per unit time)
Can be improved. Further, this peripheral exposure apparatus 1
0 is the illuminance variable unit 1 in the conventional peripheral exposure apparatus.
Since it can be configured only by adding 7, the construction is easy, and there is also an advantage of space saving because no special device for changing the illuminance of the exposure light is required.

According to the above configuration, the illuminance of the exposure light emitted from the light source unit 21 is changed in the illuminance varying unit 17 so that the illuminance becomes larger toward the outer peripheral portion of the substrate 12, so that the substrate 12 is changed. It is possible to irradiate the peripheral portion of the substrate with the exposure light L1 having the optimum illuminance over the entire area in the radial direction, and thus expose the peripheral portion of the substrate 12 over the entire area regardless of the inside and outside with the optimum irradiation light amount. It is possible to realize a peripheral exposure apparatus capable of performing the above.

Although the ND filter 30 having a trapezoidal cross section as shown in FIG. 2A is used as the illuminance varying unit 17 in the above-described embodiment, the present invention is not limited to this. As the illuminance varying unit 17, for example, a two-stage ND filter 31 as shown in FIG. 3 is used in which the thickness of the portion corresponding to the inside of the peripheral portion of the substrate 12 is thicker than the thickness of the portion corresponding to the outside of the peripheral portion of the substrate 12. Alternatively, various other illuminance varying means can be applied as the illuminance varying unit 17. When the ND filter 31 is used as the illuminance varying unit 17, the exposure light L1 irradiated on the substrate 12
2B can be changed as indicated by the solid line K11 in FIG.

Further, a liquid crystal substrate is applied as the illuminance varying section 17, and the drive current value applied to the liquid crystal substrate is changed sequentially or stepwise in the radial direction of the substrate to change the transmittance of the liquid crystal substrate in the radial direction of the substrate. It may be changed sequentially or stepwise, and various optical filters other than this may be applied.

As the illuminance varying section 17, as shown in FIG. 4, a plurality of optical fibers 41 are held by a predetermined holding member 42 so that the density of the exposure light L1 on the emission side changes in the radial direction of the substrate 12. In addition, as shown in FIG. 5, as the illuminance varying unit 17, a plurality of dimming filters 50A to 50D that change the amount of transmitted light in the radial direction of the substrate 12 are rotated plates (see FIG. (Not shown)
A neutral density filter 50A that is fixed to and used as necessary
It is also possible to apply a switch adapted to switch 50D to 50D.

Further, when it is desired to change the illuminance of the exposure light L1 applied to the peripheral portion of the substrate 12 stepwise in the radial direction of the substrate 12 when exposing the peripheral portion of the substrate 12, as shown in FIG. 51A for emitting exposure light to the peripheral portion of the
It is also possible to provide a plurality of 51C to 51C and irradiate a large amount of exposure light on the position where the illuminance is desired to be increased in the peripheral portion of the substrate 12.

Further, as the illuminance varying section 17, a diaphragm for changing the light amount of the exposure light L1 applied to the peripheral portion of the substrate 12 in the radial direction from the inner side to the outer side of the peripheral portion of the substrate 12 may be applied. good.

Further, in the above-described embodiment, the case where the present invention is applied to the peripheral exposure apparatus 10 used in the peripheral exposure process of the substrate 12 in which the resist 11B is applied on the one surface 11AX of the wafer 11A has been described. But,
The present invention is not limited to this, and can be applied to other peripheral exposure apparatuses used in various processes such as photomask substrates that handle photoresists, glass substrates for liquid crystal displays, printed boards, and photoengraving.

Further, in the above-mentioned embodiment, the case where the exposure light from the light source unit 21 is changed so that the illuminance changing unit 17 increases the illuminance of the exposure light L1 toward the outer peripheral side of the substrate 12 will be described. However, the present invention is not limited to this, and the point is that the illuminance of the exposure light from the light source unit 21 is changed from the inside to the outside of the substrate 12 according to the thickness of the resist applied to the substrate 12. The variable unit 17 may be configured.

[0034]

As described above, according to the present invention, exposure light is applied to the peripheral portion of the photosensitive surface of the exposed substrate having the photosensitive surface coated with a photosensitive material to expose the photosensitive surface of the exposed substrate. In the peripheral exposure apparatus for exposing the peripheral part of the substrate, the illuminance varying means for changing the illuminance of the exposure light applied to the peripheral part of the photosensitive surface of the exposed substrate in the direction from the inner side to the outer side of the photosensitive surface of the exposed substrate By doing so, the illuminance of the exposure light applied to the peripheral portion of the photosensitive surface of the exposed substrate can be changed according to the film thickness of the photosensitive material, and thus the peripheral portion of the photosensitive surface of the exposed substrate is always optimized. It is possible to realize a peripheral exposure apparatus capable of performing exposure with a different amount of exposure light.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of an edge exposure apparatus according to an embodiment.

FIG. 2 is a side view and a graph for explaining an illuminance varying unit.

FIG. 3 is a side view showing another embodiment of the illuminance varying unit.

FIG. 4 is a schematic diagram illustrating another embodiment of the illuminance varying unit.

FIG. 5 is a schematic diagram showing another embodiment of the illuminance varying unit.

FIG. 6 is a schematic diagram showing another embodiment of the illuminance varying unit.

FIG. 7 is a characteristic curve diagram showing a relationship between an irradiation light amount of a positive resist and a film thickness ratio after development.

FIG. 8 is a schematic cross-sectional view showing a state of a positive resist applied on a wafer.

FIG. 9 is a schematic diagram showing an exposure profile of a resist.

[Explanation of symbols]

10 ... peripheral exposure apparatus, 11A ... wafer, 11B ...
Resist, 12 ... Substrate, 17 ... Illuminance variable part, 21 ...
... light source section, 30, 31 ... ND filter, 41 ... optical fiber, 42 ... holding member, 50A to 50D ... dimming filter, 51A to 51C ... ejection section.

Claims (5)

[Claims] 1. A method of irradiating exposure light to a peripheral portion of a photosensitive surface of a substrate to be exposed having a photosensitive surface coated with a photosensitive material,
In a peripheral exposure apparatus that exposes the peripheral portion of the photosensitive surface of the exposed substrate, the illuminance of the exposure light with which the peripheral portion of the photosensitive surface of the exposed substrate is irradiated is set to the inside of the photosensitive surface of the exposed substrate. An edge exposure apparatus comprising: an illuminance varying means for changing the direction from the outside to the outside. 2. The illuminance varying means changes the illuminance of the exposure light so that the illuminance of the exposure light is greater on the outside of the peripheral portion of the substrate to be exposed than on the inside thereof. Edge exposure equipment. 3. The peripheral exposure apparatus according to claim 1, wherein the illuminance varying means is an optical filter. 4. The illuminance varying means comprises a plurality of optical fibers for guiding the exposure light to the peripheral portion of the photosensitive surface of the substrate to be exposed, and an emission end side of the exposure light of the plurality of optical fibers. The peripheral exposure apparatus according to claim 1, further comprising a holding unit that holds the plurality of optical fibers so that the densities of the plurality of optical fibers change in a direction from the inner side to the outer side of the photosensitive surface of the exposed substrate. . 5. The illuminance varying means changes the amount of the exposure light applied to the peripheral portion of the photosensitive surface of the exposed substrate in a direction from the inside of the photosensitive surface of the exposed substrate to the outside. The peripheral exposure apparatus according to claim 1, wherein the peripheral exposure apparatus is formed of a stop.