JP2011221225A - Exposure method and exposure device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To change exposure according to a temporal sensitivity variation of a resist applied to a work, and to expose the whole exposure region of one turn of a band-like work with a desired exposure accuracy.SOLUTION: A band-like work W unwound from an unwind roll 1 is conveyed to an exposure unit 3 and exposed with exposure light emitted from a light emission unit 4 via a mask M. A control unit 20 is configured to store such a parameter as a decrement amount of an exposure time corresponding to the temporal sensitivity variation of a resist applied to the work and an exposure time of the final exposure region; and the control unit 20 is configured to count the exposure frequency of the band-like work and to set up the exposure time of the exposure region which is subject to exposure based on a count value from the start of exposure and the above-mentioned parameter. Then, the control unit 20 is configured to control an opening time of a shutter board 6a of a shutter mechanism 6 in accordance with the exposure time, and to control each exposure region of the band-like work to be subject to exposure to have the above-mentioned exposure time.

Description

  The present invention relates to an exposure method and an exposure apparatus that irradiates a workpiece with exposure light through a mask and exposes (transfers) a pattern formed on the mask onto a workpiece coated with a resist, and in particular, TAB (Tape Automated). The present invention relates to an exposure method and an exposure apparatus for forming a pattern on a long strip-shaped workpiece such as Bonding and FPC (Flexible Printed Circuit).

In a display panel such as a liquid crystal display, a mobile phone, a digital camera, and an IC card, a film circuit board in which an integrated circuit is mounted on a resin film such as polyester or polyimide having a thickness of about 25 μm to 125 μm is used. In the manufacturing process, the film circuit board is, for example, a strip-shaped workpiece having a width of 160 mm, a thickness of 100 μm, and a length of several hundreds of meters, and is usually wound on a reel.
Moreover, the conductor (for example, copper foil) is affixed on the said resin film in the film circuit board. The film circuit board is manufactured by repeating a resist coating process, an exposure process for transferring a desired circuit pattern, a resist developing process, an etching process for removing unnecessary conductors, etc., for example, 4 to 5 times. Done. In each step, the film circuit board is unwound from the reel, processed, and taken up on the reel again. Hereinafter, the film circuit board is referred to as a strip-shaped workpiece.

As a prior art of a strip-shaped workpiece exposure apparatus, for example, Patent Document 1 is known. FIG. 6 shows an example of a belt-shaped workpiece exposure apparatus.
A belt-like workpiece W (hereinafter, also simply referred to as a workpiece W) is wound around the unwinding roll 1 in a roll shape so as to overlap with a spacer that protects the workpiece W. When pulling out from the unwinding roll 1, the spacer is wound around the spacer winding roll 1a. Further, the workpiece W after the exposure process is wound around the winding roll 2 while being superposed on the spacer wound out from the spacer winding roll 2a.
The strip-shaped workpiece W that has come out of the unwinding roll 1 is sandwiched between the encoder roll R3 and the pressing roll R3 ′ through the slack portion A1 and the intermediate guide roll R2. The encoder roll R3 is a roll for confirming whether or not slip has occurred in a later-described transport roll during workpiece transport.
The strip-shaped workpiece W drawn out from the unwinding roll 1 passes through the exposure unit 3 and is held between the transport roll R4 and the pressing roll R4 ′. The work W is transported by a predetermined amount set by the rotation of the transport roll R4 and is sent onto the work stage 10 of the exposure unit 3.
On the exposure unit 3, a light irradiation unit 4 having a light source composed of a lamp 4a and a condenser mirror 4b, a mask M having a pattern (mask pattern) to be exposed on a workpiece, and a projection lens 5 are provided. Yes. The work stage 10 is mounted on the work stage drive mechanism 6 and can be driven in the left-right front-rear direction and the up-down direction, and can be driven to rotate about an axis perpendicular to the work stage surface.

The light irradiation unit 4 also includes a shutter mechanism 6. The shutter mechanism 6 includes a shutter plate 6a and a shutter plate drive mechanism 6b. When the shutter plate driving mechanism 6b is driven, the shutter plate 6a is inserted into and retracted from the optical path. When the shutter plate 6a is retracted from the optical path, exposure light is irradiated from the light irradiation unit 4. When the shutter plate 6a is inserted into the optical path, the exposure light irradiation from the light irradiation unit 4 stops.
The shutter mechanism is described in Patent Document 2, for example. As described in the same document, the shutter mechanism 6 has a rotary shutter plate having, for example, a fan-shaped notch, and when the shutter plate is rotated so that the notch is positioned on the optical path, When the exposure light from the light irradiation unit 4 is irradiated onto the workpiece W through the mask M and the shutter plate is rotated so that the portion not provided with the notch is positioned on the optical path, the exposure light is irradiated. Stop.

In the exposure unit 3, the back surface side of the exposed area of the belt-like workpiece W is held on the surface of the work stage 10 by a holding means such as vacuum suction.
Alignment marks for alignment are formed on the mask M and the strip-shaped workpiece W, respectively.
When the belt-like workpiece W coated with the resist is conveyed to the exposure unit 3 and sucked and held on the workpiece stage 10, the alignment microscope (not shown) detects the alignment mark of the mask M and the alignment mark of the workpiece W, and the workpiece stage By moving 10, the mask M and the workpiece W are aligned (aligned). After the alignment is completed, the shutter mechanism 6 is opened, exposure light is irradiated from the light irradiation unit 4 through the mask M to the workpiece W, and the mask pattern formed on the mask M is exposed on the workpiece W.

The control unit 20 of the exposure apparatus turns on and off the lamp 4 a of the light irradiation unit 4, operates the shutter plate driving mechanism 6 b, unwinds the workpiece W from the unwinding roll 1, and winds up the workpiece W by the winding roll 2. It controls the operation of the entire exposure apparatus, such as the conveyance of the band-shaped workpiece W as the beginning and the alignment of the mask M and the workpiece W.
The amount of exposure for forming a pattern with a desired exposure accuracy on the resist on the work W varies depending on the resist, but has been obtained in advance by experiments. The exposure amount is represented by the product of the illuminance of the exposure light and the irradiation time during which the exposure light is irradiated, that is, the exposure time, as shown in the following formula.
Exposure amount = illuminance × exposure time Therefore, the exposure amount can be controlled by both the illuminance and the exposure time, but is controlled by the normal exposure time. The exposure time is controlled by inserting and retracting the shutter plate 6a in the optical path from the light source of the light irradiation unit 4.

JP 2009-37026 A JP 11-338005 A

Recently, resists used for exposure of strip-shaped workpieces have gradually increased in sensitivity as time passes after application. That is, as the time after application increases, the amount of exposure necessary to form (transfer) the pattern decreases.
Therefore, exposure processing is performed within a predetermined time after resist application at the factory. However, in the case of a strip-shaped workpiece, although it varies somewhat depending on the length of the workpiece, that is, the number of exposure areas formed on the workpiece and the length of the exposure time of one exposure area, on average, it takes 2 hours for one roll of exposure processing. Takes 3 hours. Therefore, the last exposure area of the workpiece is exposed 2 to 3 hours after the exposure of the first exposure area. The sensitivity of the resist gradually increases during this time.
Typical examples are as follows. The exposure time of one exposure area is about 2 seconds, the total time of the work feeding time between the exposure areas and the alignment time of the mask and the work is about 2 seconds, and the number of exposure areas is 2000. Accordingly, the processing time of the belt-like workpiece is (2 seconds + 2 seconds) × 2000 = 8000 seconds, that is, about 2 hours and 13 minutes. During this time, the optimum exposure amount is reduced by about 15% (if the illuminance is constant, if the exposure time of the first exposure region is 2 seconds, the exposure time of the last exposure region is about 1.7 seconds, That is, the exposure time is reduced by about 0.3 seconds).

Therefore, when the last exposure area of the workpiece is exposed with the exposure amount of the first exposure area, the exposure amount becomes excessive. When the amount of exposure is excessive, for example, in the case of a positive resist in which the exposed portion is dissolved in the developer, the light wraps around the portion that is desired to be left unexposed and the width of the pattern that should be left unexposed is narrow . Therefore, desired exposure accuracy cannot be obtained.
In addition, there is a resist whose sensitivity gradually decreases as time passes after application. In that case, contrary to the above, if the last exposure area of the workpiece is exposed with the exposure quantity of the first exposure area, the exposure quantity becomes insufficient. In the case of a positive type resist, the exposure amount of a portion to be exposed is insufficient and an unnecessary resist remains, and a desired exposure accuracy cannot be obtained.
The present invention has been made in view of the above circumstances, and the object of the present invention is to change the exposure amount in accordance with the change in sensitivity over time of the resist applied to the workpiece, An exposure method and an exposure apparatus capable of performing exposure with desired exposure accuracy in all exposure regions.

In order to solve the above-mentioned problems, in the present invention, when each exposure region of the strip-shaped workpiece is sequentially exposed, the exposure time is changed in accordance with the change in sensitivity over time of the resist applied to the strip-shaped workpiece.
Here, a case where the resist has a characteristic that sensitivity increases with time will be described as an example.
In this case, the exposure amount is reduced in accordance with the increase in sensitivity over time of the resist applied to the workpiece. For this purpose, as described below, an experiment or the like is performed in advance using a target resist to obtain a change in sensitivity over time, and the exposure time is controlled based on the result.
For example, a resist is applied to a workpiece, and an exposure experiment or the like is performed immediately after the coating to obtain an exposure amount (illuminance × exposure time Ts) that provides a desired exposure accuracy. From the exposure time Ts, Approximate exposure processing time (total exposure time) Ta at which everything is exposed is calculated.
In addition, after applying a resist to the workpiece, the exposure experiment is performed by leaving it for a total exposure processing time Ta, and an exposure amount (illuminance × exposure time Te) at which a desired exposure accuracy is obtained is obtained.
Then, the amount of decrease in exposure time per exposure (the difference between the nth exposure time and the (n + 1) th exposure time) Δt is obtained by the following equation (a), for example.
Δt = (Ts−Te) / (N−1) (a)
N: Number of exposure areas Based on the above, the exposure time Tn of the n-th exposure area is obtained by the following equation (b), for example.
Tn = (N−n) × Δt + Te (b)

The calculation of the exposure time may be performed by other formulas such as the following formula using the exposure time Ts immediately after coating.
Tn = Ts− (n−1) × Δt
In the case of a resist whose sensitivity gradually decreases as time passes after application, the exposure time may be controlled based on the following equation in the same manner as in the above embodiment.
Tn = (n−1) × Δt + Ts
Tn: Exposure time of the nth exposure area Δt: Increase amount of exposure time per exposure Ts: Exposure time of the first exposure area Further, instead of changing the exposure time for each exposure, a plurality of exposures You may shorten exposure time in steps for every area | region.
Further, instead of obtaining the exposure time by calculation as described above, the exposure time according to the sensitivity change of the resist may be stored in a table, and the exposure time may be read from the table.

As described above, in the present invention, by performing the following procedure, it is possible to realize exposure in which the exposure amount is changed in accordance with the change in sensitivity of the resist over time.
(1) The exposure time decrease amount Δt (or increase amount) per one exposure obtained as described above is input to the control unit of the exposure apparatus.
(2) The control unit obtains the exposure time Tn of the nth exposure region based on the decrease amount Δt (or increase amount) of the exposure time and the number of exposures.
(3) The control unit drives and controls the shutter mechanism of the light irradiation unit so that the exposure time Tn is reached for the n-th exposure region.

  In the present invention, the change in sensitivity over time of the resist applied to the belt-like workpiece is obtained, and the exposure time is changed based on this. It can be an amount. For this reason, a desired exposure accuracy can be obtained in all the exposure regions of one roll of strip-shaped workpiece.

It is a figure which shows the structural example of the exposure apparatus of the strip | belt-shaped workpiece | work of the Example of this invention. It is a figure which shows the structural example of the control part of the exposure apparatus shown in FIG. It is a figure which shows an example of the illumination intensity of the exposure light irradiated to a workpiece | work when a shutter is made into an open state. It is a figure which shows the example of the change pattern of exposure amount. It is a figure which shows the other structural example of a control part. It is a figure which shows the structural example of the exposure apparatus of a strip | belt-shaped workpiece | work.

FIG. 1 is a diagram showing a configuration example of an exposure apparatus for a strip-shaped workpiece according to an embodiment of the present invention. The apparatus shown in FIG. 1 is the same as the exposure apparatus described in FIG. 6 except that the configuration and operation of the control unit are different.
In FIG. 1, as described in FIG. 6, the strip-shaped workpiece W (hereinafter, also simply referred to as workpiece W) is pulled out from the unwinding roll 1, transported to the exposure unit 3, subjected to exposure processing, and then taken up. 2 is wound up.
On the exposure unit 3, a light irradiation unit 4 having a light source composed of a lamp 4a and a condenser mirror 4b, a mask M having a pattern (mask pattern) to be exposed on a workpiece, and a projection lens 5 are provided. The workpiece W is conveyed onto the workpiece stage 10 of the exposure unit 3 and subjected to exposure processing.
As described above, the light irradiation unit 4 includes the shutter mechanism 6 including the shutter plate 6a and the shutter plate driving mechanism 6b. Driven by the shutter plate driving mechanism 6b, the shutter plate 6a is inserted into and retracted from the optical path. When the shutter plate 6a is retracted from the optical path, exposure light is irradiated from the light irradiation unit 4. When the shutter plate 6a is inserted into the optical path, the exposure light irradiation from the light irradiation unit 4 stops.
As the shutter mechanism, for example, the one described in Patent Document 2 can be used.

As described above, the control unit 20 of the exposure apparatus turns on and off the lamp 4 a of the light irradiation unit 4, operates the shutter plate driving mechanism 6 b, unwinds the workpiece W from the unwinding roll 1, and works by the winding roll 2. The operation of the entire exposure apparatus, such as the conveyance of the belt-like workpiece W including the winding of the W and the alignment of the mask M and the workpiece W, is controlled.
In addition, the control unit is provided with a registration unit 21, from which the control unit 20 has parameters N for setting the exposure time of each exposure region, the exposure area number N, an exposure time decrease amount (increase amount) Δt, and the like. Data is input.
Further, the control unit 20 is provided with an exposure time setting unit 20a, which sets the exposure time of each exposure region based on the above parameters and controls the shutter mechanism 6.

FIG. 2 is a diagram showing a configuration example of the control unit 20, and this diagram shows a configuration example in the case of using a resist having a sensitivity increasing characteristic over time and obtaining an exposure time by calculation. Yes.
In the figure, a control unit 20 includes an exposure time setting unit 20a for setting an exposure time, turning on / off of the lamp 4a of the light irradiation unit 4, operation of the shutter mechanism 6, conveyance of the strip-shaped workpiece W, mask M and workpiece The exposure control unit 20b controls the overall operation of the exposure apparatus such as W alignment, and a storage unit 20c that stores various data. Various parameters registered from the registration unit 21 are stored in the storage unit 20c. The The control unit 20 can be configured by a computer or the like, and its function can be realized by software. FIG. 2 is a block diagram showing the functional configuration.

The exposure control unit 20b controls the entire exposure apparatus as described above, and sends an exposure completion signal to the exposure number counting unit 201 of the exposure time setting unit 20a every time exposure of one exposure area of the workpiece W is completed. To do.
The exposure time setting unit 20a includes an exposure number counting unit 201 and an exposure time calculating unit 202. The exposure count unit 201 includes a counter, and the count value is cleared to zero at the start of exposure. Each time the processing of each exposure area is completed, the count is incremented by an exposure completion signal sent from the exposure control unit 20b. That is, the count value of the exposure number counting unit 201 indicates the number of exposures n of the belt-shaped workpiece currently being exposed, and this number of exposures n is sent to the exposure time calculation unit 202.
The exposure time calculation unit 202 is based on the number of exposure areas N registered from the registration unit 21 and stored in the storage unit 20c, the amount of decrease Δt in exposure time, and the exposure time Te of the last exposure area. ) To obtain the exposure time Tn of each exposure region. Here, a case where the resist has a characteristic that sensitivity increases with time will be described as an example.
Tn = (N−n) × Δt + Te (b)
The exposure time Tn is sent to the exposure control unit 20b, and the exposure control unit 20b controls the shutter mechanism 6 based on the exposure time Tn to expose the belt-like workpiece W.

The exposure apparatus shown in FIGS. 1 and 2 operates as follows.
Parameters such as the number N of exposure areas in advance, the exposure time decrease Δt obtained in advance through experiments and the like, and the exposure time Te of the last exposure area are input from the registration unit 21 and stored in the storage unit 20c.
When exposure is started, the strip-shaped workpiece W unwound from the unwinding roll 1 as described above is sandwiched between the encoder roll R3 and the pressing roll R3 ′ through the slack portion A1 and the intermediate guide roll R2, and is exposed to the exposure portion 3. It is transported and sucked and held on the work stage 10.
On the other hand, in the exposure time setting unit 20a of the control unit 20, the number N of exposure areas input from the registration unit 21 and registered in the storage unit 20c, the exposure time decrease amount Δt, the exposure time Te of the last exposure area, and the exposure time setting Based on the count value n of the exposure count unit 201 of the unit 20a, the exposure time Tn is obtained by the above-described equation (b). The obtained exposure time Tn is sent to the exposure control unit 20b. Note that the count value n of the exposure count section 201 is initially cleared to zero, and is counted up every time exposure is completed.

On the exposure unit 3, a light irradiation unit 4, a mask M, and a projection lens 5 are provided. As described above, the exposure control unit 20b of the control unit 20 aligns (aligns) the mask M and the workpiece W. After the alignment is completed, the shutter mechanism 6 is controlled to irradiate the workpiece W with exposure light from the light irradiation unit 4 through the mask M, and the mask pattern formed on the mask M is exposed on the workpiece W. To do.
At that time, the exposure control unit 20b keeps the shutter plate 6a open for the exposure time Tn sent from the exposure time setting unit 20a, and exposes the exposure light to the work W coated with the resist through the mask M. Irradiation is performed, and the mask pattern formed on the mask M is exposed on the workpiece W. When the exposure is completed, the exposure control unit 20b sends an exposure completion signal to the exposure number counting unit 201 of the exposure time setting unit 20a. Thereby, the count value of the exposure count unit 201 is counted up.
When the count value of the number-of-exposure counting unit 201 is updated, the exposure time setting unit 202 updates the updated value of n, the number of exposure areas N, the exposure time decrease Δt, and the exposure time Te of the last exposure area. Based on the above, the exposure time Tn of the next exposure region is obtained.

When the exposure of the first exposure area on the strip-shaped workpiece W is completed, the workpiece W is sandwiched between the transport roll R4 and the pressing roll R4 ′, wound around the winding roll 2 through the slack portion A2, and on the workpiece W. The next exposure area is conveyed onto the work stage 10.
Then, as described above, the mask M and the workpiece W are aligned (aligned), and after the alignment is completed, the shutter mechanism 6 is controlled to perform the shutter for the exposure time Tn obtained by the exposure time setting unit 20a. The plate 6a is opened, and exposure light is irradiated to the workpiece W coated with the resist through the mask M.
Hereinafter, similarly, each exposure region of the strip-shaped workpiece W is sequentially exposed. The exposure time Tn decreases as the exposure process proceeds. When the last exposure area is exposed, the exposure time is about 70% of the exposure time Tn of the first exposure area, for example.
FIG. 3 shows the illuminance of exposure light applied to the workpiece W when the shutter plate 6a is open when the shutter mechanism described in Patent Document 2 is used. In the figure, the horizontal axis represents time, the vertical axis represents illuminance, and the area shown by hatching in the figure corresponds to the exposure amount.
Assuming that the exposure amount of the workpiece W when exposing the first exposure region is the amount indicated by the solid line in the figure, the time during which the shutter plate 6a is open is short when exposing the last exposure region. Thus, the exposure amount is, for example, about 70% of the exposure amount when the first exposure area is exposed, as indicated by the dotted line in FIG.

Next, how to determine the exposure time Tn will be described. Here, an example is shown in which a resist whose sensitivity increases with time is used. The exposure time Tn is obtained by the following procedure, for example.
(1) A resist whose sensitivity increases with time is applied to the workpiece W, and an exposure experiment is performed immediately after the application to obtain an exposure amount (illuminance × exposure time Ts) at which a desired exposure accuracy can be obtained.
(2) From the exposure time Ts, an approximate exposure processing time (total exposure time) Ta in which all of the wound belt-shaped workpiece is exposed is calculated by the following equation (c). The calculation formula is as follows (assuming no change in illuminance).
Ta = (Ts + Th) × N (c)
Here, Ta: Total exposure processing time Th: Total work feeding time between exposure areas, mask and work alignment time, etc. N: Number of exposure areas (3) Total exposure processing time after applying resist to work W An exposure experiment is performed by leaving Ta, and an exposure amount (illuminance × exposure time Te) at which a desired exposure accuracy is obtained with the same illuminance as in the experiment in (1) above is obtained. Ts is the exposure time of the first exposure area, and Te is the exposure time of the last exposure area.
(4) The amount of decrease in exposure time per exposure (difference between the n-th exposure time and the (n + 1) -th exposure time) Δt is obtained by the equation (a). That is, the exposure time Te of the last exposure region is subtracted from between the exposure times Ts of the first exposure region, and divided by the number of exposure regions N minus 1.
Δt = (Ts−Te) / (N−1) (a)

(5) The exposure time of the previous exposure is 1 × Δt longer than the exposure time Te of the last exposure area, and the exposure time Ts of the first exposure area is the exposure time of the last exposure area. As viewed from Tb, it is longer by (N−1) × Δt. Therefore, the exposure time Tn of the nth exposure region is expressed by the following equation (b).
Tn = (N−n) × Δt + Te (b)
Since the exposure time of Δt decreases with each exposure, the actual total exposure time is shorter than the total exposure time Ta obtained by the equation (c). However, since the decreasing exposure time is about 0.3 seconds as described above, it is ignored in the calculation. Of course, the total exposure time when the exposure time is shortened may be recalculated, the resist sensitivity increase at that time may be obtained again, and the change in exposure time may be calculated.

A method for obtaining the exposure time Tn will be described with specific numerical examples. Here, an easy-to-understand numerical value different from the actual one is used.
(1) Assume that the number N of exposure areas is 5 (times), the exposure time Ts of the first exposure area is 20 seconds, and the transfer time Th is 1 second. The exposure time Te of the last exposure area is set to 12 seconds.
(2) From equation (c), the total exposure time Ta = (Ts + Th) × N = (20 seconds + 2 seconds) × 5 = 110 seconds (3) From the above, the optimum exposure time Te after 110 seconds after resist coating is determined. Ask. Assume that Te is 12 seconds.
From equation (a), the amount of decrease in exposure time per exposure Δt = (Ts−Te) / (N−1) = (20 seconds−12 seconds) / (5-1) = 2 seconds (4) Registration From the unit 21 to the storage unit 20c of the control unit 20, the number of exposure areas N = 5, the exposure time Te of the last exposure area Te = 12 seconds, the amount of decrease in exposure time per exposure Δt = 2 seconds (or the first exposure area) An exposure area exposure time Ts = 20 seconds) is input and stored.

(5) Based on the formula (b), the exposure time for each number of times is obtained.
Exposure time T1 = (N−n) × Δt + Te = (5-1) × 2 seconds + 12 seconds = 20 seconds (= Ts) in the first (first) exposure area
Exposure time of second exposure area T2 = (N−n) × Δt + Te = (5-2) × 2 seconds + 12 seconds = 18 seconds Third exposure area exposure time T3 = (N−n) × Δt + Te = ( 5-3) × 2 seconds + 12 seconds = 16 seconds 4th exposure area exposure time T4 = (N−n) × Δt + Te = (5-4) × 2 seconds + 12 seconds = 14 seconds 5th (last) exposure Area exposure time T5 = (N−n) × Δt + Te = (5-5) × 2 seconds + 12 seconds = 12 seconds (= Te)
The above table is as follows.
The control unit 20 drives and controls the shutter mechanism 6 of the light irradiation unit so that the exposure time Tn obtained by the above calculation is obtained for the n-th exposure region.

In the above description, the calculation of the expression (b) is performed by the exposure time setting unit 20a. For example, from the registration unit, the exposure time Ts of the first exposure region, the exposure time Te of the last exposure region, and the number of exposure regions N may be input, and the exposure time setting unit 20a may perform the operations (a) and (b) to obtain Tn.
Further, as described above, the exposure time may be calculated by the following formula using the exposure time Ts immediately after coating.
Tn = Ts− (n−1) × Δt
Further, in the above description, the case where the sensitivity of the resist is gradually improved as time passes after the application has been described, but in the case of the resist whose sensitivity gradually decreases as time passes after the application, the above-described implementation is performed. Considering the same as the example, the exposure time may be controlled based on the following equation.
Tn = (n−1) × Δt + Ts
here,
Tn: Exposure time of the nth exposure area Δt: Increase amount of exposure time per exposure Ts: Exposure time of first exposure area

  In the above embodiment, the number of exposures is counted to determine the exposure time relative to the number of exposures, but instead of counting the exposure time, the elapsed time from the start of exposure (or after resist application). The exposure amount may be controlled by calculating the exposure time according to the elapsed time.

By the way, as described above, since the exposure amount is the product of the illuminance and the exposure time, it can be controlled not only by the exposure time but also by the magnitude of the illuminance. When the illuminance is controlled, a neutral density filter is inserted in the optical path or the power supplied to the lamp is changed. However, it is disadvantageous to control the exposure amount by the illuminance for the following reasons, and it is more advantageous to control the exposure time.
(1) When using a neutral density filter, it is necessary to newly provide a neutral density filter that can continuously change the amount of light transmitted through the light irradiation unit. The number of parts increases, leading to increased equipment costs.
(2) In the case of a discharge lamp, it is difficult to finely adjust the illuminance by changing the power.
(3) The exposure time can be controlled by changing only the opening / closing time of the shutter. Control is easy and there is no need to increase the number of parts. In addition, since the exposure time gradually decreases, the overall processing time can be shortened.

In the above embodiment, the exposure time is changed for each exposure. However, the exposure time may be shortened step by step for each of a plurality of exposure regions as long as the exposure amount is within the allowable range. For example, as described above, if the exposure time is reduced from 2 seconds to 1.7 seconds with respect to 2000 exposure areas, the first to 500th exposure areas have an exposure time of 2 seconds and 501st. The exposure time may be shortened stepwise, from 1.9 seconds to 1000th, 1.8 seconds from 1001 to 1500th, and 1.7 seconds from 1501 to 2000th. .
FIG. 4 shows an example of a change pattern of the exposure amount when the sensitivity of the resist gradually improves as time passes after application. FIG. 4A shows a case where the exposure amount is linearly reduced in proportion to time, and FIG. 4B shows a case where the exposure amount is reduced in steps as described above in proportion to time. (C) shows a case where the exposure amount is decreased stepwise and nonlinearly. The change pattern can be appropriately selected according to the characteristics of the resist used.

FIG. 5 is a diagram illustrating another configuration example of the control unit 20. This figure shows a configuration example in which the exposure time is read out from a previously created table instead of calculating the exposure time.
This configuration example is suitable for application when the exposure amount is changed stepwise as shown in FIGS. 4B and 4C, or when the sensitivity characteristic of the resist changes nonlinearly with respect to time. It is.
In the same figure, 20a is an exposure time setting unit for setting the exposure time, 20b is lighting / extinguishing of the lamp 4a of the light irradiation unit 4, operation of the shutter mechanism 5, conveyance of the belt-like workpiece W, mask M and workpiece W An exposure control unit 20 c that controls the overall operation of the exposure apparatus such as alignment, and a storage unit 20 c that stores various parameters registered from the registration unit 21.
The exposure time setting unit 20a includes the above-described exposure number counting unit 201 and a table reference unit 203 that reads the exposure time from the exposure time table 204 stored in the storage unit 20c.
The exposure time table 204 is a table in which the exposure time with respect to the number of exposures is registered as shown in FIG. The exposure time registered in the table 204 is set according to the sensitivity characteristics of the resist to be used, the number of exposure areas, and the like. The exposure time is created in advance based on the data obtained through the above-described experiment and registered in the storage unit 20c. .

The exposure control unit 20b controls the entire exposure apparatus as described above, and sends an exposure completion signal to the exposure number counting unit 201 of the exposure time setting unit 20a every time exposure of one exposure area of the workpiece W is completed. To do.
As described above, the exposure number counting unit 201 of the exposure time setting unit 20a counts up by the exposure completion signal sent from the exposure control unit 20b every time the processing of each exposure area is completed, and the count value is the current exposure value. The number of exposures n of the inner strip-shaped workpiece is shown.
When the exposure count n is sent from the exposure count counter 201, the table reference unit 203 reads the exposure time corresponding to the exposure count n from the exposure time table 204, and sends it to the exposure controller 20b.
The exposure control unit 20b opens the shutter plate 6a during the exposure time Tn sent from the exposure time setting unit 20a as described above, and exposes the exposure light to the workpiece coated with the resist through the mask M. The W is irradiated and the mask pattern formed on the mask M is exposed on the workpiece W. Other operations are the same as those described with reference to FIGS.

In the above, the exposure time with respect to the number of exposures is stored in the exposure time table, but instead of registering the exposure time with respect to the elapsed time after applying the resist in the exposure time table and counting the number of exposures, The elapsed time after the start of exposure (or after resist application) may be obtained, and the exposure time may be read out to control the exposure amount. Note that the elapsed time from the start of exposure may be obtained from the number of exposures, and the exposure time corresponding to the elapsed time may be read out.
Further, a plurality of tables corresponding to the sensitivity characteristics of different resists may be stored in the storage unit 20c, and the exposure time may be set using the tables corresponding to the sensitivity characteristics of the resist to be used.

DESCRIPTION OF SYMBOLS 1 Unwinding roll 2 Winding roll 3 Exposure part 4 Light irradiation part 4a Lamp 4b Condensing mirror 5 Projection lens 6 Shutter mechanism 6a Shutter plate 6b Shutter plate drive mechanism 10 Work stage 20 Control part 20a Exposure time setting part 20b Exposure control part 20c storage unit 201 exposure count unit 202 exposure time calculation unit 204 exposure time table 203 table reference unit 21 registration unit M mask W band-like work

Claims (4)

In an exposure method of irradiating a plurality of exposure areas formed on a strip-shaped workpiece with exposure light through a mask and exposing a pattern formed on the mask onto the workpiece,
An exposure method characterized by changing the exposure time in accordance with a change in sensitivity over time of a resist applied to the belt-like workpiece when sequentially exposing each exposure region of the roll-like workpiece. A decrease or increase amount Δt of the exposure time per exposure is obtained from the exposure time of one exposure area and the sensitivity change characteristic of the resist sensitivity with time, and the exposure starts with this decrease amount or increase amount Δt. 2. The exposure method according to claim 1, wherein an exposure time for each exposure region is determined based on an elapsed time from the start. A light irradiation unit provided with a light source that emits exposure light, and a shutter mechanism that inserts and retracts a shutter into the optical path of light from the light source;
A mask stage that supports the mask on which the pattern is formed;
A work stage for holding a strip-shaped work on which a pattern is exposed;
An exposure apparatus for a strip-shaped workpiece provided with a control unit for controlling exposure of each exposure area of the strip-shaped workpiece,
The control unit includes a counting unit that counts the number of exposures, and an exposure time setting unit that sets an exposure time of each exposure region,
The exposure time setting unit obtains the exposure time of each exposure region based on the count value of the count unit,
The strip-shaped workpiece exposure apparatus, wherein the control unit controls the shutter drive mechanism in accordance with the exposure time obtained by the exposure time setting unit to control the insertion / retraction time of the shutter. The exposure time setting unit sets the exposure time for one exposure area, the amount of decrease or increase Δt in exposure time obtained from the sensitivity change characteristic of resist sensitivity with time, and each exposure area. 4. The exposure time of each exposure area is obtained based on a time required for exposure, a count value n in a counting unit for counting the number of exposures, and a preset number N of exposure areas. The strip-shaped workpiece exposure apparatus described.

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