JP2925268B2 - Energy amount control device and method - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an energy amount control apparatus and method for controlling an irradiation energy amount to a sensitive object, and particularly to a reticle using a light beam from a pulse laser in a semiconductor manufacturing apparatus. The present invention relates to an energy amount control device and method suitable for controlling the exposure amount when illuminating a wafer or a wafer for exposure.

[Conventional technology]

2. Description of the Related Art Recent semiconductor electronic circuits have been increasingly integrated and miniaturized. In addition, the optical exposure system has been expanding its area by development of a lens with high resolution. In an exposure apparatus for manufacturing such a semiconductor, when a circuit pattern of a mask or a reticle is transferred onto a wafer surface and printed, the resolution line width of the circuit pattern printed on the wafer surface is proportional to the wavelength of the exposure light. Conventionally, an Hg lamp has been used as a light source for such a device for ultraviolet light, and an ultra-high pressure Xe-Hg has been used for deep ultraviolet light.

However, with such light, the sensitivity of the resist applied on the wafer is weak, so that a long exposure time is required,
There was a problem that workability was poor.

On the other hand, in recent years, a light source having an oscillation wavelength in a high-output far-ultraviolet region called an excimer laser has been used in various fields. This excimer laser is very effective as a light source for an exposure apparatus in semiconductor manufacturing because of its high brightness, monochromaticity and short coherence length.

[Problems to be solved by the invention]

By the way, when the excimer laser is used as the light source of the illumination optical system of the exposure apparatus and the amount of energy applied to the wafer surface is to be adjusted, the excitation voltage of the excimer laser is controlled by the discharge excitation method, so the discharge excitation voltage is controlled. This can be done by doing However, in such a method, if the excitation voltage is too high, the laser or the excitation circuit is broken, and if the excitation voltage is too low, the laser does not oscillate. It is generally very difficult to adjust the irradiation energy amount with high accuracy.

Excimer lasers are high-power pulse oscillations,
Since the light emission time is very short, about 10 to 20 msec, it is difficult to control the irradiation energy amount precisely by controlling the irradiation time.

A method of adjusting the irradiation energy amount using an ND filter has also been considered. However, even in this method, when the filter is moved into and out of the optical path between each pulse emission, the motor must be enlarged in order to minimize the startup time of the motor of the moving device for moving the filter. There is a problem that must be.

In view of such a problem, an object of the present invention is to provide an energy amount control device having a simple configuration, which can always control the irradiation energy amount to an appropriate value in a stable state for a long time. In particular, in the present invention, an energy amount control apparatus and method suitable for use in exposure amount control of an exposure apparatus for projecting and exposing a circuit pattern onto a photosensitive material surface such as a photoresist on a wafer surface by using pulsed light emission. For the purpose of providing.

[Means for solving the problem]

In order to solve the above-described problem, an energy amount control device of the present invention includes an energy source that generates radiant energy in a pulsed form, and an energy variable member that changes a rate at which the radiant energy is applied to an irradiation surface according to a state. And stopping the energy variable member in order to change the state of the energy variable member at least from when the irradiation of the radiation surface to the irradiation surface is started until the predetermined energy amount is irradiated to the irradiation surface. It is characterized by having a driving means for continuously driving without causing it to operate and a control means for controlling the energy generation timing of the energy source according to the state of the energy variable member.

In the energy amount control device according to the present invention, it is more preferable that a ratio of the radiant energy applied to the irradiation surface changes according to a position or a posture of the energy variable member. Further, the energy variable member, a plurality of semi-transmissive members having different transmittances, an optical block formed with a plurality of semi-transmissive surfaces each having a different transmittance,
It may have a plurality of reflecting surfaces, aperture stops, or interference filters, each having a different reflectance.

Further, the energy amount control method of the present invention prepares an energy variable member that changes the ratio of radiant energy generated in a pulse form from an energy source to an irradiation surface according to a state, and at least the radiant energy of the radiant energy is adjusted. From the start of irradiation to the irradiation surface until the irradiation surface is irradiated with the predetermined energy amount, the energy variable member is continuously driven without stopping in order to change the state of the energy variable member. Subsequently, the energy generation timing of the energy source is controlled according to the state of the energy variable member.

In the energy amount control method of the present invention, it is more preferable that a ratio of the radiant energy applied to the irradiation surface changes in accordance with a position or a posture of the energy variable member. Further, the energy variable member may include a plurality of semi-transmissive members having different transmittances.

〔Example〕

FIG. 1, FIG. 2 and FIG. 3 are schematic diagrams showing a first embodiment of the present invention. In FIG. 1, 1 is an excimer laser which is a pulse laser having good directivity, 2 is an energy control unit, 3 is a drive control unit for driving the energy control unit 2, and 4 is an energy control unit. A central controller for controlling the excimer laser 1 and the drive controller 3; 5, an illumination optical system as a first lens group; 6, a reflecting mirror that transmits some light; A monitoring device including a light receiving element for measuring the amount of light, that is, the amount of energy of the light, 8 a reticle, 9 a projection surface on which a wafer is held, and 10 a second surface for projecting the pattern of the reticle 8 onto the projection surface 9. A projection optical system 11, which is a lens group, has an optical axis of an optical path to exposure surface 9 of exposure light emitted from excimer laser 1.

FIG. 2 is a detailed view of the energy control unit 2 of FIG. In FIG. 2, reference numeral 21 denotes a rotating plate intercepting the optical axis 11, 26 denotes a motor for rotating the rotating plate 21 about an axis substantially parallel to the optical axis 11, and 27 denotes a rotation speed of the motor 26. And an encoder for detecting the position (rotation angle). The motor 26 and the encoder 27 are connected to the drive control device 3, respectively.

FIG. 3 is a view of the energy control unit 2 in FIG. 2 as viewed from the direction of the optical axis 11 (the left-right direction in FIG. 2). In FIG. 3, reference numeral 22 denotes a through hole formed in the rotating plate 21, and reference numeral 23 denotes a through hole formed in the rotating plate 21, and 3/4 of the incident energy amount (exposure light from the excimer laser 1) is used. The transmitting ND filter, 24, is mounted in a through hole opened in the rotating plate 21, and the ND filter transmitting half of the incident energy is transmitted, and the 25 is mounted in a through hole opened in the rotating plate 21, and N that transmits 1/4 of the energy
It is a D filter.

Through hole 22, ND filter 23, ND filter 24 and ND
The filter 25 is divided into four equal parts (90
At intervals), through holes 22, ND filters 2
3. The center of each of the ND filter 24 and the ND filter 25 passes through the center of the optical axis 11 by the rotation of the rotating plate 21. Further, the ND filters 22, 24,
The correspondence between 25 and the rotation angle signal of the encoder is stored in the central controller 4 in advance.

In the above configuration, the motor 26 is driven by the drive control unit 3 based on the rotation speed feedback signal from the encoder 27.
Is rotated at a predetermined constant speed by a drive command signal from The rotating plate 21 of the energy control unit 2 is rotated by the motor 26. Here, a predetermined appropriate exposure amount (hereinafter, referred to as an exposure energy amount) for the surface 9 to be exposed.
In the case of performing the exposure, the central control unit 4 detects the rotation angle signal of the rotary plate 21 from the encoder 27 through the drive control unit 3, and the excimer laser is first detected at the timing when the through hole 22 coincides with the optical axis 11. A command is issued to the excimer laser 1 so that the pulse 1 emits light. In this case, the emission timing of the excimer laser 1 is synchronized with the rotation of the motor 26 so that the emitted pulse light always passes through the through hole 22. Then, the monitoring device 7 measures the pulse energy amount (the amount corresponding to the actual exposure amount of the wafer) of each pulse emitted by the excimer laser 1 and integrates the measured values, and the necessary integration, that is, the exposure energy amount Is reached, the central controller 4 stops the emission of the excimer laser 1. These determinations are made by the central control unit 4, and the integration of the pulse energy amount may be made by the central control unit 4.

However, in this state, the control of the exposure energy amount can be controlled only by the number of exposure pulses. For example, there is a 1% difference between 100 pulses and 101 pulses, but it is not possible to control to perform exposure for 100.5 pulses.

Therefore, in the apparatus of the present embodiment, when it is determined that the required exposure energy is reached with the pulse energy of one pulse or less during the exposure, the underexposure energy is calculated by the monitoring device 7 and the central control device 4. , 0 pulse equivalent, 1/4 pulse equivalent, 1/2 pulse equivalent, 3/4 pulse equivalent, and 1 pulse equivalent pulse energy amount, select the one closest to the above-mentioned insufficient exposure energy amount. If the pulse is equivalent to 0 pulses, the emission of the last pulse is stopped. If the above selection result is equivalent to 1/4 pulse, the center of the ND filter 25 attached to the rotating plate 21 is positioned at the optical axis.
The central controller 4 gives a command to the excimer laser 1 based on the rotation angle signal from the encoder 27 so that the last one pulse is emitted at the timing passing through 11. Similarly, if the selection result is equivalent to 1/2 pulse, the encoder 27 emits the last one pulse at the timing when the center of the ND filter 24 attached to the rotating plate 21 passes through the optical axis 11.
The central controller 4 gives a command to the excimer laser 1 based on the rotation angle signal from the ND filter 23 attached to the rotating plate 21 if the above selection result is equivalent to 3/4 pulse. The central controller 4 gives a command to the excimer laser 1 based on the rotation angle signal from the encoder 27 so that the last one pulse is emitted at the passing timing. If the above selection result is equivalent to one pulse, the rotating plate 21
A command is given to the excimer laser 1 from the central controller 4 based on the rotation angle signal from the encoder 27 so that the last pulse is emitted at the timing when the center of the through hole 22 passes through the optical axis 11. As described above, the exposure energy amount control using the energy amount of 1/4 pulse as a unit can be performed without particularly adjusting the energy amount of the pulse light emitted by the excimer laser 1.

Here, assuming that the total number of light emission pulses in the above-described exposure operation is n pulses, the rotating plate 21 is rotating at a constant speed, so that the time interval between each light emission pulse from the first pulse to the (n-1) th pulse is obtained. Is equal to the time during which the rotary plate 21 makes one rotation. Assuming that this time is t, the time interval between the (n-1) th pulse and the nth pulse is an integral multiple of t / 4.

In the above-described embodiment, the rotating plate 21 is rotated at a constant speed. However, the driving device 3 controls the rotation speed of the motor 26 to perform acceleration / deceleration, or allows the rotation speed to have a degree of freedom. It is also possible to put. In this case, the center of each of the through hole 22, the ND filter 23, the ND filter 24, and the ND filter 25 is set in the same manner as described above.
The central controller 4 may give a command synchronized to the excimer laser 1 so as to emit a pulse at a timing passing through the center of the optical axis 11 by the rotation of.

Further, in the above-described embodiment, the through hole is formed during one rotation of the rotating plate 21.
However, if a plurality of the through holes 22 are provided in the rotating plate 21, the pulse light generated by the excimer laser 1 can be directly irradiated onto the wafer when the excimer laser 1 emits light. Since the rotation of the rotating plate 21 is not required, the rotating speed of the rotating plate 21 can be reduced.

Further, in the above-described embodiment, the energy amount is corrected by the last pulse emission of one exposure operation. However, the energy amount can be corrected by a plurality of pulse emissions, not limited to the last pulse. For example, when the correction is performed using the through-hole 22 and the ND filters having three kinds of transmittances, that is, the 1 / 8-transmission ND filter, the 1 / 4-transmission ND filter, and the 1 / 2-transmission ND filter, the correction is equivalent to 1/16 pulse. The exposure energy amount can be controlled with the resolution of the energy amount.

Hereinafter, the operation of this embodiment in this case will be described in detail with reference to the flowchart shown in FIG. In this case, in FIG. 3, 23 is a 1/2 transmission ND filter, and 24 is 1
/ 4 transmission ND filter, 25 is a 1/8 transmission ND filter.

In the flowchart of FIG. 10, in step 101, the proper exposure amount A necessary for printing the pattern of the reticle 8 on the wafer held on the projection surface 9 and the pulse light emitted by the excimer laser 1 are shown. A light emission amount of one pulse, that is, an amount C by which the wafer is exposed by one pulse of light emission is set. The proper exposure amount A and the one-pulse light emission amount C are set for the central controller 4. When the one-pulse light emission amount C is set, the central controller 4 sets one light emission amount of the excimer laser 1. A light emission adjustment command signal is generated to the excimer laser 1 so that the value becomes a value.

Thereafter, when an exposure start command is issued, the central controller 4 starts the rotation of the rotary plate 21 by the motor 26 via the drive controller 3 in step 102. At the start of exposure, the pulse light emitted by the excimer laser 1 is filtered by filters 23, 24,
Since it is preferable from the viewpoint of throughput that it is preferable to use for exposure without attenuating by 25, step 103
In the rotary plate based on the rotation angle signal from the encoder 27
When the center of the through hole 22 of 21 coincides with the optical axis 11, that is, the through hole
When 21 is within the exposure light path, a determination process is performed so that the process proceeds to step 104. In step 103, the center of the through hole 22 is the optical axis 1
If it is determined that they coincide with each other, the excimer laser 1 is emitted in step 104, and the actual exposure amount by this one pulse light is measured by the monitoring device 7, and the measured value is the actual exposure amount up to the present. B is integrated in step 105. Thereafter, in step 106, the set proper exposure amount A
It is determined whether or not the difference between the actual exposure amount B and the actual exposure amount B (hereinafter referred to as an underexposure amount) is smaller than the one-pulse light emission amount, that is, the one-pulse exposure amount C. If not, the process returns to step 103 to repeat the above operation. .

If it is determined in step 106 that the underexposure amount (AB) is smaller than the one-pulse exposure amount C, the process proceeds to step 107, where the underexposure amount (AB) is equal to the one-pulse exposure amount C.
It is determined whether it is 15/16 or more. This determination is based on the fact that the adjustment exposure using the filter in this embodiment is performed for one pulse exposure amount C.
Since only 1/8 is possible, the underexposure amount (AB) is 1
When the pulse exposure amount C is 15/16 or more, the filters 23 and 2
It is provided that the final exposure shortage (AB) at the end of the exposure is smaller when one pulse exposure is performed again through the through hole 22 than when the adjustment exposure using the steps 4 and 25 is performed.

If it is determined in step 107 that the underexposure amount (AB) is 15/16 or more of the one-pulse exposure amount C, step 108
It is determined whether the through hole 21 coincides with the exposure optical path,
When they match, in step 109 the excimer laser 1 emits light based on the set light emission amount C. Thereafter, at step 110, the measured value of the monitoring device 7 at this time is integrated as the actual exposure amount B, and the routine proceeds to step 111. In step 111, the underexposure amount (A−B) is set to one pulse exposure amount C.
It is determined whether it is larger than 1/16 or smaller than 1/16. If the difference is smaller than 1/16 of the one-pulse exposure amount C, the rotation of the rotary plate 21 by the motor 26 is stopped in step 115, and then in step 116 Exposure ends with. This is the amount of underexposure (AB)
Is less than 1/16 of the 1-pulse exposure C, it is better to terminate the exposure as it is than to additionally perform 1/8 of the 1-pulse exposure C using the filter 25. This is because the final exposure shortage (AB) at the end of exposure becomes smaller.

On the other hand, if it is determined in step 111 that the underexposure amount (AB) is larger than 1/16 of the one pulse exposure amount C,
In order to additionally perform exposure using the 1/8 transmission ND filter 25, the process proceeds to step 112, and when it is determined based on the rotation angle signal from the encoder 27 that the filter 25 matches the exposure optical path, step 113 is performed. The excimer laser 1 is made to emit light, and the measured value of the monitoring device 7 at that time is integrated into the actual exposure amount B in step 114, and thereafter, the process returns to step 111. The operation sequence of steps 112 to 114 is repeated until it is determined in step 111 that the underexposure amount (AB) is 1/16 or less of the one pulse exposure amount C.

If it is determined in step 107 that the underexposure amount (AB) is smaller than 15/16 of the one-pulse exposure amount C,
The sequence proceeds to step 120, whereafter the filters 23, 2
The adjustment exposure sequence using 4 and 25 is executed. The adjustment exposure sequence includes exposure using a 1/2 transmission ND filter 23, exposure using a 1/4 transmission ND filter 24, and exposure using a 1/8 transmission ND filter 25 so that the adjustment exposure is performed efficiently. Are determined in the order of.

In the adjustment exposure sequence, first, in step 120, it is determined whether or not the exposure non-measurement amount (AB) is equal to or more than 1/2 of the one-pulse exposure amount C. If so, 1/2
Step to perform exposure using the transmission ND filter 23
At 121, when it is determined that the filter 23 coincides with the exposure optical path based on the rotation angle signal from the encoder 27, the excimer laser 1 is emitted at step 122, and the measurement value of the monitoring device 7 at that time is obtained. Actual exposure amount B in step 123
To be integrated. After this, return to step 120,
This operation is repeated until it is determined that the unexposed quantity (AB) is smaller than 1/2 of the one-pulse exposure quantity C.

On the other hand, if it is determined in step 120 that the underexposure amount (AB) is smaller than 1/2 of the one-pulse exposure amount C, the process proceeds to step 130, where the underexposure amount (AB) is set to 1 It is determined whether or not the pulse exposure amount C is 1/4 or more. If so, the process proceeds to step 131 to perform exposure using the 1/4 transmission ND filter 24, where the filter 24 matches the exposure optical path based on the rotation angle signal from the encoder 27. When it is determined, the excimer laser 1 is emitted in step 132, and the planned value of the monitoring device 7 at that time is added to the actual exposure amount B in step 133. Thereafter, the process returns to step 130, where the amount of underexposure (AB) is determined.
This operation is repeated until it is determined that is smaller than 1/4 of the one pulse exposure amount C.

When it is determined in step 130 that the underexposure amount (AB) is smaller than 1/4 of the one-pulse exposure amount C, the process proceeds to step 140, where the underexposure amount (AB) is set to 1 It is determined whether the pulse exposure amount C is 1/8 or more. If so, the process proceeds to step 141 to perform exposure using the 1/8 transmission ND filter 25, where the filter 25 matches the exposure optical path based on the rotation angle signal from the encoder 27. When the judgment is made, the excimer laser 1 is emitted in step 142, and the measured value of the monitoring device 7 at that time is added to the actual exposure amount B in step 143. Thereafter, the process returns to step 140, where the amount of underexposure (AB) is determined.
This operation is repeated until it is determined that is smaller than 1/8 of the one pulse exposure amount C.

If it is determined in step 140 that the underexposure amount (AB) is smaller than 1/8 of the one-pulse exposure amount C, the adjustment exposure sequence in steps 120 to 143 is completed, and the process proceeds to step 111. The final adjustment exposure sequence after step 111 is executed. The operations after step 111 are performed as described above. When the underexposure amount (AB) becomes 1/16 or less of the one pulse exposure amount C, the rotation of the rotary plate 21 by the motor 26 is performed at step 115. After stopping, the exposure ends. In the case where the exposure apparatus shown in FIG. 1 is a step-and-repeat type so-called stepper, it is not necessary to stop the rotation of the rotary plate 21 each time exposure of each shot area on the wafer is completed. The rotation may be continued until the exposure of all the above shot areas is completed. Also,
The rotating plate 21 may be constantly rotating.

Further, in the above-described embodiment, three types of ND filters having transmittance are used, but the present invention is not limited to this. Depending on the number of exposure adjustment steps, there may be one type, a plurality of types, or a plurality of ND filters having the same transmittance.

Further, in the above-described embodiment, the ND filter is used. However, the ND filter may be replaced with a half mirror to reflect an unnecessary energy amount.

As described above, according to the first embodiment, in the exposure apparatus using the excimer laser, the rotary apparatus provided with the through hole and the ND filter so that the through hole and the ND filter continuously enter and exit in the optical path. The optimum energy amount control can be performed by a simple system in which the plate is constantly rotated during exposure to synchronize the emission of the excimer laser with the position of the rotary plate.

Next, a second embodiment of the present invention will be described. This embodiment is an example in which the one shown in FIG. 4 is used as the energy control unit 2 in the configuration of FIG.

In FIG. 4, reference numeral 30 denotes an optical member for transmitting light emitted from the excimer laser 1 and having a rectangular cross section. 31 is one surface of the tube 20, and 33 is a surface facing the surface 31 and is parallel to the surface 31. 32 is one side of the cube 30 and is perpendicular to 31. 34 is a surface facing the surface 32 and is parallel to the surface 32. 35 is the center of rotation at the center of the cross section of the cube 30 (rotation along an axis perpendicular to the plane of the paper),
The cube 30 is rotated about a rotation center 35 by an actuator (not shown) and a drive control device. The excimer laser 1 is disposed at a position where the optical axis 11 of the light emitted from the excimer laser 1 is perpendicular to the rotation center 35.

Here, the light that is perpendicularly incident on the surface 31 passes through the cube 30 and exits perpendicularly to the surface 33 with an energy amount of almost 100% of the incident energy amount. Similarly, light incident perpendicular to the surface 33 passes through the cube 30 and exits perpendicular to the surface 31 with an energy amount of almost 100% of the incident energy amount. on the other hand,
A semi-transmissive film is provided on the surfaces 32 and 34 so that light incident perpendicular to the surface 32 passes through the cube 30 and exits perpendicular to the surface 34 with an energy amount of 1/2 of the incident energy amount. It is. Similarly, light incident perpendicular to the surface 34 passes through the cube 30 and exits perpendicularly to the surface 32 with half the energy of the incident energy.

In the above configuration, when performing exposure on the surface 9 to be exposed with a predetermined amount of exposure energy, the central controller 4 starts rotation of the cube 30 about the axis 35 and then emits the light from the excimer laser 1. The optical axis 11 of the light
Synchronization is performed so that the excimer laser 1 emits light at the timing when the light is vertically incident on 33 and 34. In this case, the total exposure energy amount is determined in a unit of 1/2 of the energy amount per one pulse of the excimer laser by combining the above four types of surfaces with the number of laser light pulses incident on each surface. Becomes possible. That is, excimer laser 1
In this case, the energy amount can be controlled with an energy amount of 1/2 of the energy amount per one pulse. In addition,
In the present embodiment, the cube 30 having a rectangular cross section is used, but another polyhedron may be used. Next, examples of other polyhedrons will be described.

FIG. 5 shows a third embodiment of the present invention. This embodiment is an embodiment in which the cube 30 having a rectangular cross section of the above-described second embodiment is formed into a pentagonal cross section, and FIG. 5 is a detailed view of the energy amount control unit 2 in FIG.

In FIG. 5, reference numeral 40 denotes a light beam of light emitted from the excimer laser 1, 41 denotes an optical member having a regular pentagonal cross section and through which the excimer laser light 40 passes, and 42 denotes a rotation center located at the center of gravity of the regular pentagon of the optical member 41. It is. The optical member 41 is always rotating around the axis 42 during exposure.

In the above configuration, the excimer laser 1 is synchronized so as to emit light only at five positions existing during one rotation of the optical member 41 such that the light beam 40 always passes through the same optical path. Thus, the light beam 40 can always be emitted while maintaining the same optical path. In addition, the fact that light is emitted only at five positions existing during one rotation of the optical member 41 means that the optical member 41 does not emit light.
Has five types of optical paths. Here, by performing processing so that an appropriate semi-transmissive film is disposed on the five surfaces of the optical member 41 through which the light beam enters and exits, five types of transmittance can be given to the five types of optical paths. And
The transmittance at each of the five positions existing during one rotation of the optical member 41 is known in advance, and the excimer laser 1 is used.
The central controller 4 calculates which of the above five points and how many times the light is emitted, thereby making it possible to control the energy amount in units equal to or less than the energy amount per pulse of the excimer laser 1.

FIG. 6 shows a fourth embodiment of the present invention. This embodiment is an embodiment in which reflected light is used for transmitted light of the second embodiment, and FIG. 6 is a detailed view of the energy amount control unit 2 in FIG.

In FIG. 6, reference numeral 50 denotes an optical member which reflects light emitted from the excimer laser 1 and has a square cross section. Reference numeral 51 denotes one surface of the tube 50, and 53 denotes a surface facing the surface 51 and is parallel to the surface 51. Reference numeral 52 denotes one surface of the tube 50, which is perpendicular to the surface 51. 54 is a surface facing the surface 52 and is a surface
Parallel to 52. Reference numeral 55 denotes a rotation center at the center of the cross section of the tube 50. The tube 50 is always rotated about the rotation center 55 at least during exposure by an actuator and a drive control device (not shown).

Here, the surface 51 and the surface 53 are
The surface 52 is a half mirror that reflects 50% of the incident energy, and the surface 54 is a half mirror that reflects 25% of the incident energy.

In the above configuration, when performing exposure on the exposure surface 9 with a predetermined amount of exposure energy, the central controller 4 first sets the optical axis 11 of the light emitted from the excimer laser 1 to the entirety of the rotating tube 50. The excimer laser 1 is made to emit light continuously in synchronization with the timing of a position at 45 ° with respect to the surfaces 51 and 53 which are reflection surfaces. Those lights are on surface 51
Then, the light is turned in the direction of 90 ° by the surface 53 and is incident on the illumination optical system 5 shown in FIG. Then, as in the first embodiment, the monitoring device 7 and the central control device 4 calculate the underexposure energy amount, and stop the continuous light emission when the underexposure energy amount has reached one pulse or less, Select the energy closest to the insufficient exposure energy amount among the energy amounts equivalent to 0 pulse, 1/4 pulse, 1/2 pulse, 3/4 pulse and 1 pulse. For example, the selection result is 0 pulse If so, emission of the last pulse is stopped. If the selection result is equivalent to 1/4 pulse, one pulse is emitted in synchronization with the timing at which the surface 54 of the rotating tube 50 is positioned at 45 ° with the optical axis 11. If the above selection result is equivalent to 1/2 pulse, one pulse is emitted in synchronization with the timing at which the surface 52 is positioned at 45 ° with the optical axis 11.
If the above selection result is equivalent to 3/4 pulse, the surface 52 is
One pulse is emitted in synchronism with the timing at which the optical axis 11 and the optical axis 11 are at 45 °. In this way, the exposure energy amount is controlled.

In this embodiment, in an exposure apparatus using an excimer laser, a plurality of half mirrors having different reflectivities are provided in the optical path, and they are put in and out of the optical path, and the positions of the plurality of half mirrors and the emission of the excimer laser are synchronized. Thus, energy amount control is performed.

7 and 8 show a fifth embodiment of the present invention. 7 and 8 are detailed views of the energy amount control unit 2 in FIG. 1, and FIG. 8 is a side view as viewed from the direction of the optical axis 11 in FIG.

7 and 8, 11a is a cross section of the optical axis 11, 4
0a is a cross section of the outermost peripheral portion of the light beam 40, 61 has a position where the light beam 40 is completely blocked or not blocked at all by rotating, and the amount of light blocked can be changed steplessly during the rotation. It is a rotating plate with. Reference numeral 60 denotes a rotation center of the rotating plate 61.

In the above configuration, the rotating plate 61 is continuously rotated by the motor 26 during the exposure, and the central controller 4 detects the position of the rotating plate 61 by the encoder 27 and the drive control unit 3. Here, when the central controller 4 requires a predetermined exposure energy amount on the surface 9 to be exposed, the central controller 4
Detects the position of the rotary plate 61 by the encoder 27 and the drive control unit 3 and gives a command to the excimer laser 1 so that the rotary plate 61 continuously emits a pulse at a position where the light beam 40 does not block the passage of the light flux 40 at all. Then, the energy amount is measured by the monitoring device 7, continuous emission is stopped when the required energy amount is reached with the exposure energy one pulse lower during the exposure, and the insufficient exposure energy amount is monitored by the monitoring device 7 and the central control device 4. The central controller 4 gives a command to the excimer laser 1 so that one pulse for adjustment is emitted at the position of the rotary plate 61 where an energy amount equivalent to the underexposure energy amount passes. As described above, the timing of the emission of the rotating plate 61 and the excimer laser 1 makes it possible to control the energy amount.

FIG. 9 shows a sixth embodiment of the present invention. FIG. 9 is a detailed view of the energy amount control unit 2 of FIG.

In FIG. 9, reference numeral 70 denotes an interference filter in which the amount of transmitted energy changes according to the incident angle of light, and reference numeral 71 denotes a rotation center at which the interference filter moves, which is a linear axis perpendicular to the paper surface. The interference filter 70 is reciprocatingly rotated within a predetermined angle around a rotation center 71 by an actuator (not shown). The interference filter 70 is large enough not to block the light beam 40 in the reciprocating rotational movement. Also,
Interference filter for optical axis 11 by sensor not shown
70 angles are constantly detected.

In the above configuration, the interference filter 70 is continuously reciprocatingly rotating during the exposure, and when the central control device 4 needs a predetermined amount of energy on the surface 9 to be exposed, the central control device 4 uses a sensor (not shown). The position of the interference filter 70 is detected, and an instruction is given to the excimer laser 1 so that the amount of transmitted energy is continuously pulsed at the maximum timing.

Then, the energy amount of each pulse is measured and integrated by the monitoring device 7, the light emission is stopped once when the required energy amount is reached with the exposure energy of one pulse or less during the exposure, and the monitoring device 7 and the central control device 4 The under-energy amount is calculated, and the central control unit 4 gives a command to the excimer laser 1 so that the last pulse is emitted at the angle of the interference filter 70 through which the energy amount equivalent to the under-energy amount passes.

In addition, since the measurement is always performed by the monitoring device 7 instead of the correction using only the last one pulse, it is possible to perform the correction from a plurality of pulses before that so that the target total energy amount can be controlled. It is. In this case, it is possible to reduce the range of the reciprocating rotational movement of the interference filter 70 and increase the transmittance when the amount of transmitted energy is minimized. In other words, a large angle change must be given to make the transmitted energy amount of the interference filter 70 close to 0, and the interference filter needs to be large in order for the interference filter 70 not to block the light beam 40. In order to shorten the time, it is necessary to shorten the light emission interval of the excimer laser 1, and it is necessary to increase the reciprocating rotational movement of the interference filter at a high speed.

Also, by providing a plurality of interference filters in the optical path and synchronizing the reciprocating rotational movements of the interference filters, the amount of movement of the reciprocating rotational movement of one interference filter is small, and the decrease in the amount of transmitted energy per sheet is small. However, it is possible to obtain a large attenuation by passing light through a plurality of interference filters. As described above, in the present embodiment, the interference filter that reciprocates in the optical path is provided, and the energy amount is controlled with a simple configuration that synchronizes the angle of the interference filter with the emission of the excimer laser. . The interference filter may be of a reflection type.

The six embodiments have been described above, but it is sufficiently possible to combine a plurality of them. As described above, it is difficult to greatly change the output energy by controlling the excitation voltage of the excimer laser, but it is not possible to slightly change the output energy. By combining with the invention, more efficient energy amount control becomes possible.

〔The invention's effect〕

As described above, according to the present invention, there is provided an energy amount control device having a simple configuration capable of always controlling the irradiation energy amount to an appropriate value in a stable state for a long time. In particular, the energy control apparatus according to the present invention is suitable for use when projecting and exposing a circuit pattern onto a photosensitive material surface such as a photoresist on a wafer surface.

[Brief description of the drawings]

FIG. 1 is an overall system configuration diagram of an exposure apparatus to which an energy control apparatus according to one embodiment of the present invention is applied, and FIGS. 2 and 3 are detailed views of an energy control section according to the first embodiment. Fig. 4 is a detailed view of the energy control section according to the second embodiment, Fig. 5 is a detailed view of the energy control section according to the third embodiment, and Fig. 6 is a view according to the fourth embodiment. 7 and 8 are detailed diagrams of the energy amount control unit according to the fifth embodiment, FIG. 9 is a detailed diagram of the energy amount control unit according to the sixth embodiment, FIG. 10 is a flowchart for explaining the operation of the first embodiment. 1. Excimer laser 2. Energy control device 4. Central control device 21. Rotating plate.

Claims (10)

(57) [Claims] 1. An energy source for generating radiant energy in a pulse form, an energy variable member for changing a rate of irradiation of the radiant energy onto an irradiation surface in accordance with a state,
Stopping the energy variable member in order to change the state of the energy variable member at least from when the irradiation of the radiation surface to the irradiation surface is started until the predetermined amount of energy is irradiated to the irradiation surface. An energy amount control device, comprising: a driving unit that continuously drives the energy source without any change; and a control unit that controls timing of generating energy of the energy source according to a state of the energy variable member. 2. The energy amount control device according to claim 1, wherein a rate at which the radiant energy is irradiated on the irradiation surface changes according to a position or a posture of the energy variable member. 3. The energy control apparatus according to claim 1, wherein said energy variable member has a plurality of semi-transmissive members having different transmittances. 4. The energy amount control device according to claim 1, wherein the energy variable member has an optical block on which a plurality of semi-transmission surfaces having different transmittances are formed. 5. An energy control apparatus according to claim 1, wherein said energy variable member has a plurality of reflection surfaces having different reflectivities. 6. The energy control device according to claim 1, wherein the energy variable member has an aperture stop. 7. The energy control device according to claim 1, wherein said energy variable member has an interference filter. 8. An energy variable member for changing a rate of irradiation of radiant energy generated in a pulse form from an energy source to an irradiation surface according to a state is provided, and at least irradiation of the irradiation surface with the radiant energy is performed. From the start until the irradiation surface is irradiated with the predetermined energy amount, the energy variable member is continuously driven without stopping in order to change the state of the energy variable member, and the energy variable member is Controlling the energy generation timing of the energy source according to the state of the energy source. 9. The energy amount control method according to claim 8, wherein a rate at which the radiant energy is applied to the irradiation surface changes according to a position or a posture of the energy variable member. 10. The energy control method according to claim 8, wherein the energy variable member has a plurality of semi-transmissive members having different transmittances.