JPH01251613A - Method and apparatus for photoelectric transfer and exposure - Google Patents

Abstract

PURPOSE:To prevent defects in a photoelectron transferring mask and in a wafer, by accelerating and focusing photoelectrons generated by irradiating the photoelectron transferring mask with light, and exposing the wafer to the light while correcting an exposing position. CONSTITUTION:A photoelectron transferring mask 2 which is patterned with photoelectron emitting parts formed of a photoelectron emitting material and photoelectron non-emitting parts is faced to a light source 5'. An electrode plate 8 has a linear aperture 8a for passing photoelectrons emitted by the photoelectron transferring mask 3. An electric field generating means 4 is provided between the electrode plate 8 and the mask 3 so that the means 4 generates an electric field for accelerating the photoelectrons. Photoelectrons are excited and emitted from the photoelectron transferring mask 3 by light applied thereto, and once focused at the aperture on the electrode plate 8. The focusing position is adjusted by moving the mask 3 and the electrode plate 8 in the direction of the Z axis. A magnetic field means corrects the position of photoelectrons which are passed through the aperture 8a of the electrode plate 8 and focused on a wafer 31.

Description

[Detailed Description of the Invention] [Summary] A photoelectronic transfer exposure device and method used in photolithography technology as an LSI manufacturing technology, which prevents defects in photoelectronic transfer masks and defects in samples (wafers). The exposure apparatus includes a light source, a photoelectron transfer mask arranged opposite to the light source and patterned with a photoelectron emitting part and a non-photoelectron emitting part formed of a photoelectron emitting material, an electrode plate having a line-shaped opening through which photoelectrons emitted from the transfer mask pass; an electric field generating means for generating an electric field between the electrode plate and the photoelectron transfer mask to accelerate the photoelectrons; and a photoelectron transfer mask. A magnetic field generating means that generates a uniform magnetic field between the object to be exposed on the stage and focuses the photoelectrons, and a deflector that adjusts the position where the photoelectrons that have passed through the opening of the electrode plate form an image on the object on the stage. means for accelerating and focusing photoelectrons generated by irradiating light onto the photoelectron transfer mask, and
This is an exposure method in which exposure is performed while correcting the exposure position.

[Industrial application field]

The present invention relates to a photoelectronic transfer exposure apparatus and method used in phosphorography technology as an LSI manufacturing technology.

[Conventional technology]

Ultraviolet exposure methods have been used as a lithography technique for a long time.Since then, ultraviolet exposure methods have been repeatedly improved to make patterns finer, but the wavelength of light (
4,000 people), the limits of miniaturization were pointed out.
Technologies such as an electron beam exposure method, an X-ray exposure method, and a photoelectron transfer exposure method are being considered.

In the electron beam exposure method, an electron beam with a dot-shaped or rectangular cross section is deflected, irradiated onto the wafer without changing its position, and a stage is moved to draw a fine pattern on the wafer. , direct exposure without using a mask is also possible.

However, in addition to an electron source, a column system for focusing, shaping, and deflecting the electron beam, and a stage system for supporting the wafer and changing the exposure position, a control system for controlling these is required. Although this method can hope to improve resolution, it takes a long time to expose because it uses so-called "-brush writing" exposure based on a huge amount of pattern data, and the throughput is low, making it unsuitable for mass production. It's fleeting.

Further, the X-ray exposure method is a proximity exposure method in which a large-scale X-ray light source of, for example, 10 to 50 kW is used and X-rays having a wavelength of 1 to 10 people are used. Therefore, in X-ray exposure, in addition to the light source described above, a combination of a mask and an aligner that supports the wafer and can align both with high precision is required. In this respect, it is similar to the ultraviolet exposure method described above, but the light source is large-scale and expensive, the mask constituent material must be considered due to the relationship between the absorption coefficient and the light source wavelength, and furthermore, due to proximity exposure, the wafer The larger the diameter, the more the mask bends and the mask and wafer warp.As a result, the gap between the mask and the wafer varies, causing blurring. It is difficult to obtain strong X-ray intensity, and the throughput is not very good. Furthermore, it has been proposed to use synchrotron radiation, which has strong X-ray intensity and parallel light, as the above-mentioned X-ray generation light source, but this would require a large-scale device.
In addition, the manufacturing and operation of the equipment is extremely expensive.
Furthermore, it is difficult to use and cannot be said to be suitable for practical exposure equipment.

As an exposure method that takes advantage of both the high throughput of the transfer method and the high resolution of the electron beam exposure method, there is a transfer exposure method using photoelectrons. In this exposure method, a photoelectron emitting material and a non-emitting material are used in advance on the mask.
In this method, photoelectrons generated by irradiating the mask with light are accelerated and focused by an electric field and a magnetic field applied between the mask and the wafer, and transferred onto the wafer.

FIG. 7 shows an example of a conventional photoelectronic transfer exposure apparatus. 7th
In the figure, a photoelectronic transfer mask 2 and a stage 3 are arranged at right angles to the parallel magnetic field (vertical direction in the figure) formed by a focusing coil (Helmholtz coil) 1, and therefore,
The photoelectronic transfer mask 2 and the stage 3 are arranged to face each other. Reference numeral 4 denotes a DC power supply that accelerates photoelectrons by setting the photoelectron transfer mask 2 at a negative potential with respect to the stage 3.

5 is a light source, for example an ultraviolet source, and 6 is a deflection coil for positioning.

The photoelectronic transfer mask 2 has a transparent substrate (for example, 500 to 6
00 tone quartz plate) 21 with an ultraviolet absorber (for example, Cr).
) is formed, and a photoelectron emitting material film 23 is further deposited thereon.

Note that the photoelectron emitting material emits electrons upon irradiation with ultraviolet rays, and is cesium iodide (Csl) or platinum (Pt).

A sample, such as a wafer 31, is placed on the stage 3. This wafer 31 has an electron beam photosensitive agent (resist) 32.
is coated.

In FIG. 5, when the photoelectronic transfer mask 2 is irradiated with ultraviolet rays 5a from the light source 5, the light is transmitted to the ultraviolet absorber pattern 2.
The portions of the photoelectron emitting material film 23 where photoelectrons 2 are not formed are irradiated, and as a result, photoelectrons 7 are generated as shown in the figure. The photoelectrons 7 are accelerated while moving in a spiral manner by an accelerating voltage generated by the DC power source 4 and a parallel magnetic field generated by the focusing coil 1, and are imaged, that is, focused, on the wafer 31. As a result, the pattern on the photoelectronic transfer mask 2 can be transferred and exposed onto the wafer 31.

Further, in order to align the photoelectronic transfer mask 2 and the wafer 31, a backscattered electron detector (not shown) is provided between the photoelectronic transfer mask 2 and the wafer 31. This detector detects the electron beam generated when electrons generated from the alignment mark on the photoelectronic transfer mask 2 hit the mark on the wafer 31. Note that during this alignment, the deflection coil 6
The photoelectrons 7 are caused to scan.

[Issues that Hathu tries to solve]

However, in the above-mentioned photoelectronic transfer exposure apparatus,
During exposure, defects may occur in the photoelectronic transfer mask 2 due to so-called resist scattering or the like. That is, the photoelectron transfer mask 2 and the wafer 31 face each other as electrode plates, and an acceleration voltage for accelerating photoelectrons is applied between them, so that discharge occurs. As described above, when a defect occurs in the photoelectronic transfer mask 2, the defect is transferred to all exposed wafers 31, resulting in a problem that defective products continue to be produced.

Also, during alignment, since the accelerating voltage of the photoelectron 7 is applied between the photoelectron transfer mask 2 and the wafer 31, an electric field is present near the wafer 31, and as a result, alignment from the wafer 31 The reflected electrons will eventually cover the wafer 31 again. Therefore, a problem arises in that areas that are not exposed to light are also exposed to light. Furthermore, when the wafer 31 is warped, the warp disturbs the electric field near the surface of the wafer 31, which causes pattern distortion and leads to defective products.

Therefore, an object of the present invention is to provide a photoelectronic transfer exposure apparatus and method that prevents the occurrence of defects in photoelectronic transfer masks and defects in samples (wafers).

[Means to solve the problem]

A means for solving the above problem is shown in FIG.

That is, the photoelectron transfer mask 2 is patterned with a photoelectron emitting part and a non-photoelectron emitting part made of a photoelectron emitting material, and is placed facing the light source 5'. The electrode plate 8 has a linear opening 8a through which photoelectrons emitted from the photoelectron transfer mask 2 pass. An electric field generating means 4 is provided between the electrode plate 8 and the photoelectron transfer mask 2 for generating an electric field to accelerate photoelectrons.

The photoelectrons are excited and emitted from the photoelectron transfer mask 2 by the light emitted from the light source 5'. These electrons are once imaged onto the opening on the electrode plate 8. The imaging position is adjusted by moving the photoelectronic transfer mask 2 and the electrode plate 8 in two axial directions. The magnetic field means is the opening 8a of the electrode plate 8.
The photoelectrons passing through the object (wafer) 31 on the stage 3
This is to correct the position of the photoelectrons imaged above.

[For production]

According to the above-mentioned means, even if a discharge occurs between the photoelectronic transfer mask 2 and the electrode plate 8, the discharge is unlikely to occur between the photoelectronic transfer mask 2 and the wafer 31. Accordingly,
The possibility that the resist on the wafer 31 will scatter onto the photoelectronic transfer mask 2 is small. Further, even if the resist on the wafer 31 is scattered, most of it will cover the electrode plate 8.

Furthermore, a backscattered electron detector can be connected to the electrode plate 8 for detecting alignment signals, but since there is no electric field near the wafer 31, there is a possibility that the wafer 31 will eventually be affected by backscattered electrons during alignment. is small.

〔Example〕

FIG. 2 is a diagram showing an embodiment of the photoelectronic transfer exposure apparatus according to the present invention, and FIG. 3 is a diagram showing another embodiment. Note that FIG. 2 shows a system in which the focusing part (magnetic field generating part) is a coil and light is emitted from the back of the mask, and FIG. 3 shows a system in which the focusing part is a permanent coil and light is emitted from the mask surface.

In FIGS. 2 and 3, an electrode plate 8 having a line-shaped opening 8a is added to the components shown in FIG. 8.

Therefore, due to the presence of the electrode plate 8, the photoelectronic transfer mask 2
Almost no discharge occurs between the stage 3 and the stage 3 (wafer 31), and as a result, the resist is not scattered from the wafer 31 and covers the photoelectronic transfer mask 2. Therefore, there are no defects on the photoelectronic transfer mask 2 due to resist scattering. is unlikely to occur. Furthermore, no voltage is applied between the electrode plate 8 and the wafer 31, so that the reflected electrons from the wafer 31 return from the electrode plate 8 and do not impinge on the wafer 31.

The light source 5' is, for example, a mercury-xenon lamp or an ultra-high pressure mercury lamp, and its ultraviolet light is irradiated onto the photoelectron transfer mask 2 through a line-shaped window 9, and the electrons generated from the photoelectron transfer mask 2 are It passes through the linear opening 8a of the electrode plate 8. In this case, the size of the irradiated light from the window 9 is made smaller than the size of the opening 8a of the electrode plate 8. That is, as shown in FIG. 4, the length and width of the irradiated light are L and d+, and the length of the opening 8a of the electrode plate 8 is
If the widths are β2 and d2, then 1, <β2 d, <d2. As a result, the photoelectrons generated from the photoelectron transfer mask 2 are not affected by leakage of the electric field from the edge of the opening 8a of the electrode plate 8, and distortion of the photoelectron beam can therefore be prevented. Further, the width d2 of the opening 8a of the electrode plate 8 is 1 of the width of the exposure area of the photoelectronic transfer mask 2 (smaller than the mask 2).
/10 to 1/20 is good. If the width d2 is too large, the electric field applied between the photoelectron transfer mask 2 and the electrode plate 8 will leak through the aperture 8a, resulting in increased distortion of the photoelectron beam, and if the width d2 is too small, the exposure This is because efficiency decreases. Further, the length β2 of the opening 8a of the electrode plate 8 is 1.2 to 1.2 of the length of the exposure area of the photoelectronic transfer mask 2.
Twice as much is better. As shown in FIG. 4, the irradiation light passing through the window 9 is incident on the photoelectronic transfer mask 2 at right angles, but it can also be made obliquely incident on the photoelectronic transfer mask 2. As a result, even if there is light passing through the photoelectronic transfer mask 2, the light can be prevented from directly hitting the wafer 31. Also, the light source 5 can be used without using the window 9.
', the second harmonic of an Ar laser (Ar half-wavelength wave=257.25 nm, 244 nm) may be scanned in a line.

2 and 3, 10 is a mask stage for moving the photoelectronic transfer mask 2, 11 is a deflection coil, 12 is a vacuum chamber, and 13 is an exhaust port. Deflection coil 11
, together with the focusing coil 1, provide a parallel or perpendicular magnetic field to the photoelectron beam, and, for example, correct the reduction ratio and rotation of the photoelectron beam image. Furthermore, although not shown, an electromagnetic deflector, an electrostatic deflector, and a backscattered electron detector (PIN diode) (as shown in FIG. 6) are installed below the opening 8a of the electrode plate 8 so as to surround the linear photoelectron beam. 14.15.16) are provided.

These deflectors deflect the photoelectron beam in mutually orthogonal directions.

FIG. 5 is a block circuit diagram of a control section that controls the main parts of FIG. 2. In FIG. 5, 501 is a CPU;
2. 503 is a magnetic disk or magnetic tape for storing data, and 504 is an interface.

The CPU 501 connects the light source 5 via the interface 504.
' and the shutter 17 of the light source 5'.

Further, 506 is a focusing system control unit, and a motor 50 that moves the mask stage 10 and the electrode plate 8 in the Z direction.
7a, 507b, a driver for driving the deflection coil 11 (
DAC/AMP) 508, photoelectronic transfer mask 2- (
A driver (DAC/AMP) 509 that applies an accelerating voltage to the mask stage 10) is controlled. Also, 510
is a deflection control section, which is a driver (D) of the electromagnetic deflector 14;
AC/AMP) 511 and a driver (DAC/Al, IP) 512 of the electrostatic deflector 15. Also,
513 is a stage control unit, which controls stage 1 for mask.
0 motor 514 and stage 3 motor 515 are controlled. Furthermore, 516 is a laser length measurement unit (for example, a laser interferometer) that detects the position of each stage 10.3 in the X and Y directions.

The operation of the control section shown in FIG. 5 will be explained.

The light source 5' is turned on, the shutter 17 is opened, and the photoelectronic transfer mask 2 and the wafer 31 are aligned. Positioning is performed using the backscattered electron detector 16 (FIG. 6) as described above. At this time, the mask stage 10
The photoelectron beam is once focused on the aperture 8a of the electrode plate 8 by adjusting both or one of the positions of the electrode plate 8 in the Z direction. Image distortion, reduction ratio, and rotation are corrected by the deflection coil 11.

Thereafter, the photoelectronic transfer mask 2 (i.e. mask stage 10) and the wafer 31 (i.e. stage 3
) are moved in the vertical direction in FIG. 2 at a constant speed determined by the required exposure amount of the resist 32, for example, 1Q mm/s. At this time, the light source 5' and the electrode plate 8 are in a stopped state.

In this way, the exposure beam of the photoelectronic transfer mask 2 is rendered on the wafer 31 in a 1:1 ratio. Note that the constant speed described above is not necessarily required, and the photoelectronic transfer mask 2 and wafer 3
1 should be moving at the same speed. -Also, by varying the moving speed of the photoelectronic transfer mask 2 and the moving speed of the wafer 31 and keeping the ratio constant, it is possible to reduce or enlarge the exposure pattern. For example, if the moving speed of the wafer 31 is set to 115 with respect to the moving speed of the photoelectronic transfer mask 2, 115 reduction exposures can be performed. In this case, the photoelectronic transfer mask 2 used is one enlarged five times in the direction of movement.

Further, although the movement of the photoelectronic transfer mask 2 and the movement of the wafer 31 are performed as synchronized as possible by the CPU 501, in reality, a movement error occurs between them.

Therefore, the position of the mask stage 10 and the position of the stage 3 are detected by the laser length measurement unit (laser interferometer) 516, and the position error is fed back to the electromagnetic deflector 14 and the electrostatic deflector 1''5. For example, if the movement of the photoelectronic transfer mask 2
If the deflector 14.1 is relatively slow relative to the movement of
On the other hand, if the movement of the photoelectronic transfer mask 2 is relatively fast with respect to the movement of the wafer 31, it may be swung back by the deflectors 14 and 15.

FIG. 6 is a partially enlarged view showing still another embodiment of the photoelectronic transfer exposure apparatus according to the present invention. In FIG. 6, partition walls 17 and 18 are provided with the electrode plate 8 as a boundary, thereby dividing the vacuum chamber into a vacuum chamber 12A on the photoelectronic transfer mask 2 side and a vacuum chamber 12B on the wafer 31 side. In this way,
By performing differential evacuation across the electrode plates 8, it is possible to maintain the vacuum degree of the vacuum chamber 12A on the photoelectronic transfer mask 2 side at 10'''8 Torr regardless of the presence or absence of the wafer 31.

Note that 19 is a wafer holder.

In the above embodiment, the photoelectron transfer mask 2 and the wafer 31 are moved and the light source 5' and the electrode plate 8 are stopped, but conversely, the light source 5' and the electrode plate 8 are moved. , the photoelectronic transfer mask 2 and the wafer 31 can also be stopped. In this case, reduction and enlargement exposure is not possible, but the apparatus for moving the light source 5' in the atmosphere and the electrode plate 8 at ground potential is simple.

〔Effect of the invention〕

As explained above, according to the present invention, since discharge is difficult to occur between the photoelectron transfer mask and the exposed object (wafer) and because of the presence of the electrode plate, photoelectrons due to scattering of the resist on the wafer, etc. Defects in the transfer mask can be reduced, and therefore defects in the wafer can also be reduced. Also, since there is no electric field near the wafer, there is little possibility that the wafer will be hit by reflected electrons during alignment, so the wafer can still be damaged. defects can be reduced.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the basic principle of the present invention, FIGS. 2 and 3 are diagrams showing an embodiment of the photoelectronic transfer exposure apparatus according to the present invention, and FIG. 4 is a diagram showing the size of the electrode plate in FIG. 2. FIG. 5 is a circuit diagram showing the control section of FIG. 2, FIG. 6 is a diagram showing still another embodiment of the photoelectronic transfer exposure apparatus according to the present invention, and FIG. 7 is a conventional photoelectronic transfer exposure device. It is a figure showing an apparatus. 3... Stage, 4... DC power supply, 5.5
'...Light source, End...Electrode plate, 8a...Line opening, 9...Window, 10...Mask stage, 12A, 12B...Vacuum chamber, 14...Electromagnetic deflection 15... Electrostatic deflector, 16... Backscattered electron detector.

Claims (1)

[Claims] 1. A light source (5'), and a photoelectron transfer mask (2) arranged opposite to the light source and patterned with a photoelectron emitting part and a non-photoelectron emitting part formed of a photoelectron emitting material. ) and a line-shaped opening (8) through which photoelectrons emitted from the photoelectron transfer mask pass.
a); an electric field generating means (4) for generating an electric field between the electrode plate and the photoelectron transfer mask to accelerate the photoelectrons; Stage photoelectrons (3)
A photoelectronic transfer exposure apparatus comprising: magnetic field generating means (1) for forming an image on an upper object (31). 2. The photoelectronic transfer exposure apparatus according to claim 1, wherein the light source includes means (9) for generating light having a cross-sectional shape smaller than the opening of the electrode plate. 3. The photoelectronic transfer exposure apparatus according to claim 1, wherein the light source irradiates the photoelectronic transfer mask with light formed by scanning a laser. 4. The photoelectronic transfer exposure apparatus according to claim 1, wherein the light source irradiates the photoelectronic transfer mask with light obliquely. 5. The photoelectronic transfer exposure apparatus according to claim 1, further comprising mask/stage moving means for moving the photoelectronic transfer mask and the stage at a constant relative speed with respect to the electrode plate. 6. The mask/stage moving means makes the relative speed between the photoelectronic transfer mask and the electrode plate different from the relative speed between the stage and the electrode plate, thereby changing the exposure pattern of the photoelectronic transfer mask. 6. The photoelectronic transfer exposure apparatus according to claim 5, wherein the exposure is performed while reducing/enlarging the object on the stage. 7. Further, mask position detection means (516) for detecting the position of the photoelectronic transfer mask, and stage position detection means (516) for detecting the position of the stage.
516), position error calculation means (501) for calculating a relative position error between the position of the stage and the position of the photoelectronic transfer mask, and forming an image on the object on the stage according to the relative position error. a first deflection means (14,
15) The photoelectronic transfer exposure apparatus according to claim 5, comprising: 8. Further, a light source that moves the light source and the electrode plate in synchronization.
The photoelectronic transfer exposure apparatus according to claim 1, further comprising electrode moving means. 9. The photoelectron transfer exposure apparatus according to claim 1, further comprising means for forming an image of photoelectrons emitted from the photoelectron transfer mask onto the electrode plate. 10. The photoelectronic transfer exposure apparatus according to claim 1, wherein the vacuum chamber of the apparatus is divided by the electrode plate. 11, further comprising: a backscattered electron detector (16) connected to the electrode plate; and a second deflection means (16) for aligning the photoelectronic transfer mask and the stage according to the output of the backscattered electron detector.
11) The photoelectronic transfer exposure apparatus according to claim 1, comprising: 12. A photoelectron transfer mask (2) arranged facing the light source and patterned with a photoelectron emitting part and a non-photoelectron emitting part made of a photoelectron emitting material, and passing through the photoelectrons emitted from the photoelectron transfer mask. An electric field is generated between the electrode plate (8) having a line-shaped opening (8a) to accelerate the photoelectrons, and the photoelectrons passing through the opening of the electrode plate are transferred to the stage (3).
A photoelectronic transfer exposure method in which an image is formed on the upper object (31). 13. The photoelectron transfer exposure method according to claim 12, further comprising: moving the photoelectron transfer mask and the stage at a constant relative speed with respect to the electrode plate. 14. Further, detecting the position of the photoelectronic transfer mask, detecting the position of the stage, calculating a relative positional error between the position of the stage and the position of the photoelectronic transfer mask, and determining the position according to the relative positional error. 14. The photoelectron transfer exposure method according to claim 13, wherein the photoelectron position imaged on the object on the stage is corrected by using the photoelectron transfer exposure method. 15. The photoelectron transfer exposure method according to claim 12, further comprising forming an image of photoelectrons emitted from the photoelectron transfer mask onto the electrode plate. 16. The photoelectron transfer exposure method according to claim 12, further comprising aligning the photoelectron transfer mask and the stage in accordance with the output of a backscattered electron detector connected to the electrode plate.