JP2877352B2 - X-ray exposure equipment - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exposure apparatus used for manufacturing ICs and LSIs, and more particularly, to an exposure apparatus that uses synchrotron radiation as exposure light.

[Conventional technology]

As integrated circuits have become finer, the line width of a pattern transferred by exposure has become smaller, and the line width of a resist has also become stricter. As is well known, the line width of the resist greatly changes with the change of the exposure amount. Therefore, it is important to control the actual exposure amount so as to exactly match the desired exposure amount. As a method for strictly controlling the exposure amount, JP-A-57-101839 and JP-A-59-198726
As disclosed in Japanese Patent Application Laid-Open No. H10-209, there is a method in which a detector is installed near a mask to measure the intensity of exposure light during exposure, and the shutter is closed when a desired exposure amount is reached.

[Problems to be solved by the invention]

However, in X-ray exposure using synchrotron radiation (hereinafter, referred to as “SOR”), which has been receiving attention in recent years, it is difficult to use the conventional technology as it is. This is because, in the conventional apparatus, the region where the intensity of the exposure light was uniform was relatively wide, so that there was no significant difference from the intensity in the exposure region even at the intensity measurement position around the mask.
This is because, in the exposure method according to the above, since the area where the intensity of the SOR as the exposure light is uniform is narrow, the X-ray intensity differs between the measurement position and the exposure area.

Therefore, when the exposure is not performed, the X-ray detector is extended to the exposure area to measure the X-ray intensity, and the exposure time is determined based on the measured value, and the X-ray is detected so as not to block the X-ray during the exposure. A method of detecting the exposure intensity at which the container is retracted can be considered.
However, when the X-ray intensity changes every moment as in SOR, there is a difference in X-ray intensity between the measurement time and the exposure time,
There may be new errors.

SUMMARY OF THE INVENTION An object of the present invention is to provide an X-ray exposure apparatus capable of measuring X-ray intensity with high accuracy even when SOR is used, in view of the above-described problems in the conventional type.

(Means for Solving the Problems) According to the present invention for solving the above problems, in an X-ray exposure apparatus for exposing and transferring a pattern on a mask onto a substrate by using synchrotron radiation, a radiation intensity corresponding to the inside of an exposure region is adjusted. A movable first detector which can be retracted outside the exposure area during exposure for measurement, and a second detector which is installed outside the exposure area and is different from the first for obtaining attenuation information of synchrotron radiation. And means for performing measurement with the first and second detectors before exposure and performing exposure in accordance with the attenuation of synchrotron radiation based on the outputs of these detectors. Things.

〔Example〕

 Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a conceptual diagram showing a configuration of an X-ray exposure apparatus according to one embodiment of the present invention. This X-ray exposure apparatus is based on a fixed mirror method. In the figure, 1 is a SOR ring,
3 is an X-ray mirror, 5 is an X-ray transmission window such as Be, 6 is a movable X-ray detector, 7 is a shutter, 8 is an X-ray mask, and 9 is a wafer coated with a photosensitive material. 2 indicates an X-ray, and 4 indicates an X-ray enlarged by the X-ray mirror 3. Reference numeral 10 denotes an electron injector, 11 denotes a signal processing unit, 12 denotes an X-ray detector drive unit, 13 denotes a shutter drive unit, 14 denotes an X-ray detector control unit, 15 denotes a shutter control unit, 16 denotes a CPU unit, and 17 denotes a CPU unit. Is a light or X-ray intensity detector, 18 is a signal processing unit, and 19 is a communication path.

In this embodiment, the state of the exposure light is always observed by the detector 17.

Here, the installation position of the detector 17 and the characteristics of the detector will be described. The installation position may be any position as long as it does not block the exposure X-rays. This is because the intensity of SOR observed at a position forming an angle of θ with the orbital plane varies depending on the wavelength. For example, Fig. 3 shows an acceleration voltage of 600MV and an orbital radius of 2m.
In the case (1), the dependence of the SOR intensity on θ is shown using the wavelength as a variable. The horizontal axis represents the angle θ from the orbital plane, and the vertical axis represents the unit current, the unit wavelength, and the SOR intensity per unit solid angle. As can be seen from FIG. 3, at 2 mrad or less, the intensity at the short wavelength is stronger than that at the long wavelength. Therefore, when the detector 17 can be installed on substantially the same plane as the orbital plane, a detector having sensitivity in the X-ray region or the visible region can be used.
For example, the X-ray detector may detect photoelectrons from a metal wire stretched in the optical path in addition to the semiconductor detector.
However, when θ is 2 to 3 mrad or more, the intensity at the short wavelength becomes weaker than that at the long wavelength. Therefore, a detector such as a photodiode sensitive to a long wavelength, for example, a visible region is preferable as the detector.

For example, when the detector 17 is installed in the orbit plane, it may be located adjacent to the X-ray mirror 3 as shown in FIG. Further, as shown in FIG. 1, a position A behind the X-ray mirror 3 may be used.

Generally, the SOR exposure is started after low energy electrons are injected from the injector 10 into the SOR ring 1 and accelerated to reach a predetermined energy. However, the injected electrons collide with residual gas molecules and the like existing in the trajectory of the SOR ring 1 and the number thereof gradually decreases, and the intensity of the emitted light decreases accordingly. Therefore, when the orbital electrons or the emitted X-rays fall below a certain intensity, the electrons are cut off and the exposure is interrupted. After that, electrons are incident again and exposure is started.

Next, the operation of the X-ray exposure apparatus of FIG. 1 will be described. First,
In a state where the shutter 7 is closed (the dotted line in FIG. 1), electrons are supplied from the injector 10 to the SOR ring 1 and accelerated. Thereafter, the CPU unit 16 issues an exposure intensity measurement command to measure the X-ray intensity. This is because the X-ray detector 6 is controlled by the X-ray detector driving unit 12 via the X-ray detector control unit 14.
Is fed into the exposure area (dotted line in FIG. 1), and the X-ray intensity in the exposure area is measured. At the same time, the emitted light intensity is measured by the detector 17, and the output of the detector 17 is sent to the CPU unit 16 through the signal processing unit 18. X at this time
The output of the line detector 6 and the detector 17, respectively and I _x, I _po.

The measured radiation intensity is sent to the CPU unit 16 via the signal processing unit 11, and the X-ray detector 6 is retracted outside the exposure area.

Next, immediately before the start of the exposure, the emitted light intensity I _p (t) is measured again by the detector 17, and the CPU unit 16 determines the X-ray intensity I _e (t) during the exposure based on the measured radiation intensity. Is calculated. Then, the exposure time T is calculated and set from the set exposure amount D, and the positions of the X-ray mask 8 and the wafer 9 are aligned. The exposure time T can be calculated by T = D / ( _Ie · α) when the X-ray intensity attenuation during exposure is small. Here, α is the X of the X-ray mask 8
After that, the CPU unit 16 issues an exposure command to the shutter control unit 15, whereby the shutter 7 is opened by the shutter driving unit 13 and exposure is started. After the exposure starts, when the exposure time T has been reached, the shutter 7 is closed.

Next, a method of obtaining the exposure time T will be described in more detail.

As shown in FIG. 3, the intensity of the SOR varies depending on the wavelength and the angle θ from the orbital plane, but is proportional to the orbital current at the same measurement position unless the acceleration voltage and the electron orbital change. Therefore, the output I of the detector 17a at time t
_p (t) and I _x , obtained by simultaneous measurement after electron injection
The X-ray intensity _{Ie at} time t is determined by _Ipo according to _Ipo .

For example, suppose that the set exposure amount D is 50 mJ / cm ^2, and an output of 150 mW / cm ² and 1 (arb.un.) are obtained by the X-ray intensity detector 6 and the detector 17 at the same time after electron injection. I do.
Here, the output of the detector 17 is an arbitrary unit. Next, assuming that the output of the detector 17 is 0.5 (arb.un.) at the exposure time te, the X-ray intensity I _e at that time is given by the following equation. The exposure time T becomes T = 4 seconds according to the equation (assuming that the transmittance α of the mask is 0.5).

Here, the X-ray intensity attenuation during exposure is treated as small.

Further, in the above embodiment, the detector 17 uses I _p (t)
Is preferably as short as possible immediately before the start of the exposure, that is, immediately before the start of the exposure control shutter.

Next, the case where the X-ray intensity attenuation during exposure cannot be ignored will be described. The X-ray intensity is measured in real time using the detector 17, and the exposure can be controlled by the integrated exposure _De (t).

For example, after the electron injection, the outputs I _x and I _po of the X-ray intensity detector 6 and the detector 17 are measured at the same time. Next, the output I _p (t) of the detector 17 every fixed time Δt from the time t _{1 when the} shutter 7 is opened.
Is measured and the CPU unit 16 And the integrated exposure amount D _p (t) Is calculated. Integrated exposure amount D _p (t) close the Shiyatsuta 7 When you have reached the set amount of exposure D _e.

Next, this operation will be described with reference to the flowchart of FIG.

The CPU unit 16 that controls the exposure enters a normal operation after completing the initialization processing 21 for each peripheral. The exposure start command is given from the communication path 19 and is transmitted by setting one of the service request flags. CPU unit 16
Always checks whether this service request flag is set (22). If any one of these flags is set, the request is identified (23), and processing based on the flag is started. If the flag indicates a start processing start request (exposure start), the value of the previous integrated exposure amount Is cleared, the interrupt timer is started, the shutter is opened, an end processing request flag is set, and its own request flag (start processing request flag) is cleared (24). The started timer interrupts the CPU at regular time intervals (every Δt), and the CPU interrupts the light or X-ray detector 17 in the interrupt processing routine.
Read the output I _p (t) of (25) is performed in addition to.

When the end processing request flag is set, the CPU enters the end processing sequence. In this (Accumulated exposure amount) to determine if it has reached the desired amount of exposure D _e (27), and Return if not reached, and OFF timer interrupt if you have reached, closed Shiyatsuta 7, their request flag Clear (end processing request flag) (2
8).

When a plurality of X-ray exposure apparatuses are installed in one SOR ring 1, the detector 17 does not necessarily need to be installed for each X-ray exposure apparatus. For example, as shown in FIG. 5, when only the exposure apparatus a has the detector 17 and the other apparatuses each have only the X-ray detector 6 for measuring the X-ray intensity in the exposure area, after the electron injection, In each exposure apparatus, the X-ray detector 6 is fed into the exposure area, the X-ray intensity _Ix is measured, and at the same time, the output of the detector 17 is obtained in the apparatus a. The output _{Ipo of the} detector 17 is sent to each exposure apparatus through the communication path 31. Thereafter, the exposure intensity _Ie of each device is transmitted through the communication path 31, and the CPU of each exposure device transmits the output _Ip (t) and _{Ipo of} the detector 17 at the time of the exposure, which is transferred to each device. it can be obtained by equation or the like using the measured I _x. Further, the device provided with the detector 17 does not necessarily need to be an exposure device.

〔The invention's effect〕

1. Since the X-ray intensity is measured only once after the electron injection and the subsequent X-ray intensity decay can be dealt with, efficient and highly accurate measurement is possible.

2. In addition, since the X-ray intensity can be determined in real time, it is possible to cope with a rapid change in the X-ray intensity.

3. Further, when a light intensity detector is used as the detector, precise measurement can be performed for a long time because the detector is not deteriorated by X-rays.

[Brief description of the drawings]

FIG. 1 shows an embodiment of the present invention. FIG. 2 is a diagram showing an arrangement of detectors which are components of the present invention. FIG. 3 is a diagram showing a vertical intensity distribution of SOR. FIG. 4 is a diagram showing a flowchart for controlling an exposure amount by an integrated exposure amount. FIG. 5 shows an embodiment of the present invention when a plurality of exposure apparatuses are installed on one SOR ring. 1: SOR ring 2: X-ray 3: X-ray mirror 4: Magnified X-ray 5: Be window 6: Movable X-ray detector 7: Shutter 8: X-ray mask 9: Wafer coated with photosensitive material 10 : Electron injector 11: Signal processing unit 12: X-ray detector drive unit 13: Shutter drive unit 14: X-ray detector control unit 15: Shutter control unit 16: CPU unit 17: Light or X-ray detector 18: Signal Processing unit 19: Communication path 31: Communication path

──────────────────────────────────────────────────続 き Continuing on the front page (72) Kunitaka Ozawa, 3-30-2 Shimomaruko, Ota-ku, Tokyo Inside Canon Inc. (72) Koji Uda 3-30-2, Shimomaruko, Ota-ku, Tokyo Canon (72) Inventor Shigeru Terashima 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Shunichi Uzawa 3-30-2, Shimomaruko 3-chome, Ota-ku, Tokyo Canon Inc. ( 56) References JP-A-64-26182 (JP, A) JP-A-61-179537 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) G21K 5/00-5/10 H05H 13/04 H01L 21/30

Claims (4)

(57) [Claims] An X-ray exposure apparatus for exposing and transferring a pattern on a mask onto a substrate by using synchrotron radiation.
A movable first detector capable of retracting outside the exposure area during exposure for measuring the radiation intensity corresponding to the exposure area;
A second detector, which is located outside the exposure area, for obtaining attenuation information of synchrotron radiation and is different from the first detector, and the first and second detectors perform measurement before exposure, and these detectors An X-ray exposure apparatus having means for performing exposure in accordance with the attenuation of synchrotron radiation based on the output of the X-ray exposure apparatus. 2. The method according to claim 1, wherein the first detector is retracted after the detection,
2. An X-ray exposure apparatus according to claim 1, wherein an exposure time is determined by an output of said second detector during an exposure operation. 3. An exposure time is measured by the second detector immediately before exposure, or measured and integrated at regular intervals during exposure by the second detector to determine an exposure time. The X-ray exposure apparatus according to claim 2. 4. A plurality of X-ray exposure apparatuses are installed in one synchrotron radiation source, and an output of the second detector provided corresponding to a certain X-ray exposure apparatus and another X-ray exposure apparatus are provided. Based on the output of the first detector provided corresponding to the exposure device,
2. The X-ray exposure apparatus according to claim 1, wherein exposure of each X-ray exposure apparatus is controlled.