JPH02202010A - X-ray exposing method - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an X-ray exposure method, and more particularly, to an exposure method using X-rays that is suitable for transferring a large amount of submicron patterns. .

Recently, attempts have been made to expose and use X-rays with short wavelengths.The principle is to expose and develop X-ray resists with X1Vi of several wavelengths, and there is no diffraction or interference, making it possible to form fine patterns. It has excellent characteristics.

As an X-ray source, an electron beam excitation type has been used as an easy device, but in order to obtain high output, synchrotron radiation (SOR)
It radiation) has been developed.

According to the SOR ring, it is possible to generate X&jl with good parallelism and obtain a brightness 10' to 105 times higher than that of the electron beam excitation type. When using such an SOR ring, it is important that X-rays are always stably irradiated.

[Conventional technology]

SOR-X-ray light is obtained by an SOR device, and the SOR device is composed of a linear accelerator, an acceleration ring, and a storage ring. Then, using the first stage linear accelerator, the incident electrons are accelerated by an acceleration ring, and then stored in a storage ring.
5OR-X-ray light is extracted and irradiated onto an X-ray mask to expose and transfer a pattern onto a wafer. in this case,
SOR/X-ray light is obtained by deflecting high-energy electrons using a magnetic field. These electrons are stored in the storage ring, but the lifetime of the electron beam is determined by conditions such as the vacuum of the ring, and the storage beam current reaches about 173 in a period of, for example, 10 hours. On the other hand, since X-ray exposure requires a certain intensity, conventional X-ray exposure methods measure the X-ray intensity, which is substituted by the amount of accumulated current in the storage ring.

Further, in SOR-X-ray exposure, an X-ray mirror is used to block short wavelength components in order to prevent disturbance of the transferred pattern. This X-ray mirror is heated and deformed by the irradiated X-rays. Then, due to the deformation of this mirror,
Since the X-ray spectrum incident on the mask that performs line exposure also changes, the change in the overcast spectrum is inferred from the exposed pattern.

[Problem to be solved by the invention]

However, in such conventional X-ray exposure methods, the amount of charge accumulated in the storage ring is used instead of measuring the X-ray intensity, and the irradiated X-rays are not directly measured, resulting in sudden beam instability ( A decrease in intensity due to abnormal vibrations cannot be detected, and in such a case, the exposure pattern is disturbed and stable exposure cannot be performed.

Further, a change in the spectrum when the X-ray mirror is deformed by heat cannot be detected in the same way, and is inferred from the exposure pattern, so that the same problem as above inevitably occurs in such a case as well.

Therefore, an object of the present invention is to provide an XvA exposure method that can always stably irradiate X-rays and stably expose a highly accurate pattern.

[Means to solve the problem]

In order to achieve the above object, the XvA exposure method according to the present invention
OR-X-rays are reflected by an X-ray mirror and irradiated onto the XvA mask, and the pattern of the X-ray mask is exposed to the sample, and during this exposure, the intensity and spectrum of the irradiated X-rays are detected from Compton scattering from the irradiation point, Based on the detection results, the exposure time for the sample and the angle of the X-ray mirror are changed so that the irradiated X-ray intensity and spectral distribution become predetermined values.

[Effect]

In the present invention, the irradiated X-ray intensity and spectrum are detected from Compton scattering from the irradiation point, and based on the detection results, the exposure time and the angle of the XI mirror are changed so that the irradiated X-ray intensity and spectral distribution are constant values. .

Therefore, due to Compton scattering, the X-ray intensity and spectral distribution can be detected in real time during X-ray exposure, and changes in intensity and spectrum can be corrected to enable stable exposure at all times.

〔Example〕

Hereinafter, the present invention will be explained based on the drawings.

FIG. 1.2 is a diagram showing an embodiment of the X-ray exposure method according to the present invention. FIG. 1 is a block diagram for realizing the X&'lil exposure method. In this figure, 1 indicates a partition wall of an acceleration cavity 2 in an SOR device, and the acceleration cavity 2 partitioned by the partition wall 1 is kept in a vacuum. , X-rays 3 emitted from orbiting electrons e in a storage ring (path shown) are guided. As the partition wall 1, stainless steel is used, for example. X-ray 3 is X&'! at a predetermined incident angle θ. It is reflected by the mirror 4, and at this time, short wavelength components necessary for exposure are blocked,
Furthermore, after long wavelength components are removed by a beryllium window 5, the X-ray mask 7 is irradiated through the X-ray Shaftalo. The beryllium window 5 is a thin film mainly composed of beryllium (Be), and in addition to blocking short wavelength components as described above, it is also a part of a partition for keeping the acceleration cavity 2 in a vacuum.

The X-ray mask 7 is held by a mask holding section 8, and
A wafer (sample) 9 to be exposed is placed close to the i-mask 7 . Note that the wafer 9 is on the stage 10.
Fixed. A portion of the X-rays 3 irradiated onto the X-ray mask 7 is Compton-scattered by the X-ray mask 7, and this scattered light 3a is detected by the detector 11. The detector 11 is 5i-
This is an X'43 detector using a Li-based solid-state element, and can detect the intensity and spectrum of X-rays at the same time.

Here, Compton scattering (Compton Scat
ering) refers to the scattering of X-rays (photons) by electrons. When X-rays with uniform wavelengths (monochromatic) hit electrons and are scattered, some of the scattered X-rays have the same wavelength as the incident X-ray. In addition to X-rays, the X-rays include those whose wavelengths are slightly longer than the wavelength of the incident X-rays, and because of this, the intensity and spectrum of the X-rays 3 can be detected. Note that the X-ray shutter 6, the X-ray mask 7, the mask holding part 8, the wafer 9,
The stage 10 is housed in a space filled with helium (He) gas.

The output of the detector 11 is input to a signal processing calculator 12, which processes the detection signal from the detector 11 (waveform shaping, noise component removal, etc.) and sends it to the control computer 13. Send. The control computer 13 calculates the appropriate exposure time and the incident angle of the X-ray 3 (angle of the X-ray mirror 4) from the intensity and spectrum distribution of the XvA3 detected based on the Compton scattered light 3a, and responds to the calculation results. A control signal is output to the shutter controller 14 and mirror drive driver 15. The shutter controller 14 controls the opening and closing of the X-ray shank 6 based on control signals from the control computer 13, and the mirror drive driver 15 controls the control computer 1.
The angle of the XI,1 mirror 4 is changed by controlling the operation of the mirror drive mechanism 16 based on the control signal from the XI,1 mirror 4. The mirror drive mechanism 16 is fixed to the X-ray mirror 4 and includes an extensible rod 17 made of, for example, a piezoelectric element, a bellows 18 that covers around the rod 17 and maintains airtightness of the acceleration cavity 2, and a proximal end of the rod 17. The angle of the X-ray mirror 4 is adjusted by expanding and contracting the rod 17 based on a signal from the mirror drive driver 15. Note that the X-ray mirror 4 is rotatably supported by a support section 20.

In the above configuration, the wafer 9 is fixed to the stage 10, and the X-ray mask 7 is supported by the mask holder 8 in close proximity to the wafer 9. On the other hand, the surrounding electron e of the SOR device
- The X-rays 3 emitted from the
The X-rays reach the X-ray shutter 6 through the X-rays. When exposure is started, the X-ray shutter 6 is opened, the X-ray mask 7 is irradiated with X-rays 3, and the mask pattern is transferred onto the wafer 9.

At this time, the irradiated X-ray intensity and spectrum are detected by the detector 11 from Compton scattering from the irradiation point, and the intensity is adjusted so that this intensity (for example, the amount of integration per unit time) becomes a constant value (for example, the maximum value). Calculations are performed by the control computer 13, and automatic adjustment is performed by monitoring the intensity of the X-rays 3 while moving the X-ray mirror 4 by the mirror drive mechanism 16. When the maximum value is determined, the control computer 13 sets the shutter time, and when the set time is reached, the shutter controller 14 closes the X-ray shank 6 to end the exposure.

Here, the change in the X-ray spectrum with respect to the incident angle θ of the X-ray mirror 40 is shown as shown in FIG.
It represents the power spectrum after passing through the mask 7. The conditions in this case are as follows.

SOR synchrotron radiation: E = 1.0 GeV B = 1.407 Platinum mirror: Incident angle θ = 3Q mrad Adjustment of platinum mirror: θ = 28.29.30.30.31 mrad Beryllium window: 100 μm thick Helium gas: 1 atm; 5 cm thick X'4FA mask: 3 μh thick Resist: 3 μm thick FIG. 2(b) shows how the power spectrum changes due to absorption by the resist of the X&i mask 7.

In this way, in this example, the X-ray intensity and spectral distribution are detected in real time during X-ray exposure using Compton scattering, and the detected data is widely banked for exposure.
Changes in X-ray intensity and spectrum are appropriately corrected,
X-rays can always be irradiated stably, and highly accurate patterns can be stably exposed.

〔Effect of the invention〕

According to the present invention, X-rays can always be irradiated stably, and highly accurate patterns can be stably exposed.

[Brief explanation of the drawing]

Figure 1.2 is a diagram showing an embodiment of the X-ray exposure method according to the present invention, Figure 1 is a block diagram for realizing the X-ray exposure method, and Figure 2 is an It is a figure showing a line spectrum. 2...Acceleration cavity, 3...X-ray, 4...X-ray mirror 5...Beryllium window, 6...XL2 shutter, 7...X-ray mask, 9...wafer (sample), 11...-detector, 12...signal processing calculator, 13... ...Control computer, 14...Shutter controller, 15...Mirror drive driver, 16...
・Mirror drive mechanism. FIG. 2 is a diagram showing the X-ray spectrum with respect to the mirror angle of one example.

Claims (1)

[Claims] SOR/X-rays are reflected by an X-ray mirror and irradiated onto an X-ray mask, and the pattern of the X-ray mask is exposed to the sample, and during this exposure, the irradiated X-rays are generated from Compton scattering from the irradiation point. The X-ray device is characterized in that the intensity and spectrum are detected, and based on the detection results, the exposure time for the sample and the angle of the X-ray mirror are changed so that the irradiated X-ray intensity and spectral distribution become predetermined values. Line exposure method.