JPH056852A - X-ray irradiation device and X-ray irradiation method - Google Patents

Abstract

(57) [Abstract] [PROBLEMS] To provide an X-ray extraction window which is thin, has a high transmittance for long-wavelength X-rays, and has a high strength against a pressure difference, in regard to the structure of an X-ray irradiation apparatus used for manufacturing a semiconductor device. The purpose is to An X-ray extraction window (1) provided with a thin film (2) that transmits X-rays (16) in the external atmosphere between a vacuum X-ray generator and an external atmosphere at atmospheric pressure as a partition for holding a vacuum. Mesh-like reinforcing plate 3 on at least one surface of 2
And the at least one of the thin film 2 and the irradiated body 8 is swung during the irradiation of the X-rays in order to make the irradiation amount of the X-rays 16 uniform on the surface of the irradiated body 8. Configure as.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure of an X-ray irradiator used for manufacturing a semiconductor device and an X-ray irradiating method.

With the recent trend toward higher integration and higher performance of semiconductor devices, X-ray exposure capable of forming fine patterns is considered promising. However, since the X-ray generator is kept in a vacuum, it is necessary to provide a window for transmitting the X-ray while keeping the vacuum of the apparatus in order to introduce the X-ray into the exposure apparatus in the atmosphere. The absorption of X-rays in a window is an exponential function of the thickness of the window and increases rapidly with thickness.

For this reason, there is a demand for an X-ray irradiator having an X-ray extraction window which is thin and has a strength capable of maintaining a vacuum in order to increase the X-ray transmittance.

[0004]

2. Description of the Related Art Conventionally, a beryllium thin film has been used as a window for extracting X-rays from a vacuum X-ray generator into the atmosphere.

The beryllium thin film forming this window is required to have strength to withstand the pressure difference between the inside and the outside of the X-ray generator, and therefore the beryllium thin film must be thick when a window having a large diameter is provided.

However, the thick beryllium thin film has a drawback that the X-ray transmittance is low. Further, since the thick beryllium thin film has a large absorption of long wavelength X-rays and transmits a large amount of short wavelength X-rays, there is a problem that the mask contrast in X-ray exposure is lowered and it becomes difficult to form a fine pattern. .

In order to avoid the deterioration of the mask contrast due to the short wavelength X-ray, an X-ray mask provided with a thick absorption pattern is commonly used. However, this method has a drawback that it is difficult to precisely process a thick absorption pattern.

[0008]

As described above, the conventional technique cannot provide a thin and large-diameter X-ray extraction window. Therefore, there is a drawback that a large-area irradiation target cannot be exposed in a short time or it is difficult to form a fine pattern.

It is an object of the present invention to provide an X-ray irradiator having an X-ray extraction window which is thin and has a high transmittance for long wavelength X-rays and a high strength against a pressure difference.

[0010]

FIG. 1 is an explanatory view of a first embodiment of the present invention. FIG. 1 (a) shows the main construction of an X-ray extraction window and an X-ray exposure apparatus, and FIG. 1) shows the structure of the X-ray extraction window according to the present invention, and FIG. 1C shows the AB cross section.

FIG. 2 is a partial plan view of the second embodiment of the present invention, showing the arrangement of the transmission windows provided on the reinforcing plate. A first configuration of the present invention for solving the above-mentioned problems is to vacuum a thin film 2 that transmits X-rays 16 between a vacuum X-ray generator and an external atmosphere at atmospheric pressure, with reference to FIG. X having an X-ray extraction window 1 provided as a partition for holding
In the radiation irradiator, a reinforcing plate 3 having a plurality of openings is adhered to at least one surface of the thin film 2 and is irradiated with X-rays in order to make the irradiation amount of the X-rays 16 uniform on the surface of the irradiated body 8. In the meantime, at least one of the thin film 2 and the irradiated body 8 is configured to oscillate in a plane perpendicular to the incident direction of the X-ray 16, and the second With reference to FIG. 2, the structure is the X-ray irradiating device of the first structure, in which rectangular transmission windows opened to transmit X-rays are arranged in parallel at the equal pitch on the reinforcing plate. Transparent window row 14
a1 to 14a6 are arranged in two or more rows and are arranged at equal distances parallel to each other along the transmission window row (14a1 to 14a6) one by one by a distance of an integer fraction of the pitch, and It is characterized in that it is a reciprocating motion orthogonal to the azimuth direction of the transmission window in the plane of the window and having an amplitude obtained by multiplying the center distance of the row by the integer. With reference to the X-ray irradiator of the second structure, in addition to the reciprocating motion according to the second structure, a reciprocating motion in the row direction having an amplitude exceeding a distance of an integer fraction of the pitch is performed. In the fourth configuration, with reference to FIG. 1, a reinforcing plate 3 having a plurality of openings on at least one surface is closely attached, and a vacuum X-ray generator and an external atmosphere of atmospheric pressure are provided. X-rays transmitted through the thin film 2 provided as a partition for holding a vacuum between And at least one of the objects to be irradiated 8 is irradiated on the object to be irradiated while swinging in a plane perpendicular to the incident direction of the X-ray 16, and the X on the surface of the object to be irradiated 8 is irradiated.
The feature is that the irradiation amount of the line 16 is made uniform.

[0012]

In the configuration of the present invention, referring to FIGS. 1 (b) and 1 (c), one surface of the thin film 2 made of a substance that transmits X-rays,
A large number of transmission windows 14 are provided, and the reinforcing plate 3 forming a mesh is in close contact with the ribs 15.

Therefore, the strength of the thin film 2 against the differential pressure is
It suffices that each of the transmission windows 14 has strength with respect to the size thereof, and does not require strength with respect to the size of the entire surface of the X-ray extraction window 1 as in the conventional case.

According to the experiment, the strength of the X-ray extraction window 1 with respect to the differential pressure according to the present invention is limited by the strength of the ribs 15 rather than the strength of the thin film 2 in the usual thin film 2 material, and the substantially transparent window 14 is It has a strength close to that of the reinforcing plate 3 when there is no such structure.

Therefore, the large X-ray extraction window 1 can be manufactured using the thin thin film 2 and with sufficient strength against the differential pressure, and the large-diameter X-ray extraction window 1 having a high long-wavelength X-ray transmittance. Can be realized.

Further, in this configuration, the relative position between the irradiated body 8 and the X-ray extraction window 1 swings during irradiation. Therefore, the mesh image of the X-ray extraction window 1 does not stay at the same position on the irradiated body 8 for a long time, and the spatial intensity distribution is averaged.

Therefore, even if a mesh exists in the X-ray extraction window 1, it is possible to obtain a uniform irradiation amount over the entire surface of the object to be irradiated, as in the case of a normal X-ray extraction window having no mesh.

In the second structure of the present invention, referring to FIG. 2, the transmissive window rows 14a1 to 14a6 are sequentially arranged in parallel in the row direction, and are shifted by one pitch at an integer number of times. The row 14a1 and the row 14a6 which is not displaced are arranged as one cycle, and the swing is perpendicular to the transmission window row, and the unit is the distance from the original row 14a1 to the row 14a6 which returns to the original row again. It is performed by a reciprocating motion with an amplitude that is an integral multiple of that.

In such a configuration, the amount of irradiation of one point of the irradiated object in one reciprocation is proportional to the distance that one point of the irradiated object passes through the transmissive window during the one reciprocation.
The variation of the dose along 4a1 to 14a6 is reduced only by the distance passing through at most one transmission window caused by the presence of the rib 15.

Therefore, the ratio of the spatial variation of the dose to the maximum dose is equal to the reciprocal of the number of rows included in one repetition of the transmission window row. In this configuration, the number of columns included in one repetition of the transparent window column is increased by shifting the array of the transparent windows for each column in the column direction. Therefore, it is possible to reduce the fluctuation of the irradiation amount.

Further, in the third configuration, reciprocating motion is applied also in the column direction. Therefore, the irradiation amount at one point of the irradiated body is the same as the distance passing through the transmissive window in that it is not in the shadow of the rib 15, but the shadowed portion of the rib 15 reciprocates more than the width of the rib 15. As a result, the period of shadow of the rib 15 becomes shorter.

Therefore, it is possible to reduce the variation of the dose due to the shadow of the rib, and to obtain a uniform dose distribution.

[0023]

EXAMPLES The present invention will be described with reference to examples. The first embodiment is applied to a wafer exposure apparatus using synchrotron orbit radiation as an X-ray source with reference to FIG.

Referring to FIGS. 1B and 1C, the thickness 3
A beryllium thin film 2 having a diameter of 30 μm and a reinforcing plate 3 is bonded to a stainless steel plate having a thickness of 50 μm, and a rectangular transparent window 14 having a side length of 100 μm is opened by etching the stainless steel.

As for the arrangement of the transmission windows, referring to FIG. 2, the transmission windows 14a1,1 to 14a1,3 are arranged side by side with a transmission window row 14a1 arranged at a pitch of 120 μm, and then shifted by a fifth of 120 μm. The transparent window row 14a2 has a center distance of 120
1 μm parallel arrangement, and in the same manner, the transmission window row 1
4a3 to 14a6 are arranged.

The X-ray extraction window 1 formed of the beryllium thin film 2 to which the reinforcing plate 3 having the transmission window is attached is
The transmission window rows 14a1 to 14a are attached to the window frame 4 attached to the X-ray introduction tube 17 forming a part of the ray generator via the bellows.
The reinforcing plate 3 is attached horizontally to the X-ray introducing tube 17 by a vacuum seal provided in the periphery.

The X-ray extraction window 1 having such a structure can withstand up to a pressure difference of 5 atm. On the other hand, the conventional X-ray extraction window has the same diameter of 30 mm and the same diameter of 3 mm.
Even a beryllium thin film having a thickness of μm can withstand only a 0.6 atmospheric pressure difference. Thus, according to the present invention, a thin but strong X-ray extraction window can be realized.

Furthermore, a thickness of 50 μm which is conventionally used
The beryllium thin film of No. 1 has a transmittance of 10 ⁻⁴ for long-wavelength X-rays having a wavelength of 1.5 nm, while the thickness according to the present invention is 3 μm.
In the beryllium thin film of m, the transmittance for the same wavelength is 0.
It was 62. As described above, according to the present invention, it is possible to realize an X-ray extraction window having a high transmittance, and in particular, a decrease in the transmittance at a long wavelength is small.

Therefore, even if the pattern of the X-ray mask 7 is formed of a thin layer, a high contrast can be obtained, so that the X-ray mask can be easily manufactured in the present invention. The X-ray extraction window 1 is connected to the gate valve 12 of the exposure apparatus 10 via a tube filled with helium gas that flows in and out from the gas input / output 13. Such a tube is provided to prevent deterioration of the beryllium thin film in the X-ray extraction window 1 and to reduce absorption and scattering of X-rays.

The exposure apparatus 10 is composed of a wafer holder for holding a wafer to be the object to be irradiated 8, a transmission type X-ray mask 7 and bellows connected to the gate valve 12. The X-rays 16 generated by the X-ray generator pass through the vacuum, reach the X-ray extraction window 1, pass through the X-ray extraction window 1, and are extracted into the helium atmosphere at atmospheric pressure. Irradiate as a pattern of irradiation intensity.

During irradiation, the window swinging device 6 reciprocates the window frame 4 in the vertical direction with an amplitude of 1.2 mm. Further, during irradiation, the wafer holding table 9 is reciprocally moved in the horizontal direction with an amplitude of 600 μm.

By the irradiation added with such a swing, even when the X-ray extraction window having the mesh was used, uniform exposure was performed as in the conventional window. In the present embodiment, the swinging of the window frame 4 can be responsible for all swinging. This reduces the design burden on the exposure apparatus 10.

Alternatively, the window frame may be fixed, and all the swinging may be performed by the exposure device. This makes it possible to avoid complication of the device.

[0034]

As described above, according to the present invention, the X-ray extraction window is reinforced by the mesh-shaped reinforcing plate, and
Since the radiation dose distribution is uniform, an X-ray irradiator having an X-ray extraction window having a high intensity against pressure difference formed by a thin thin film having a high long-wavelength X-ray transmittance, and a long-wavelength X-ray to be transmitted. However, it is possible to provide an X-ray irradiation method in which the amount of irradiation is large and the irradiation amount is uniform, which greatly contributes to improving the performance of the semiconductor device.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of a first embodiment of the present invention.

FIG. 2 is a partial plan view of a second embodiment of the present invention.

[Explanation of symbols]

1 X-ray extraction window 2 thin film 3 Reinforcement plate 4 window frames 5 Bellows 6 Window swing device 7 mask 8 Irradiated body 9 Wafer holder 11 Bellows 12 gate valve 13 gas inlet / outlet 14,14a1,1 to 14a6,2 Transparent window 14a1 to 14a6 Transmission window row 15 ribs 16 X-ray

Claims (4)

[Claims] 1. An X-ray extraction window (1) provided with a thin film (2) which transmits X-rays (16) as a partition for holding vacuum between a vacuum X-ray generator and an external atmosphere at atmospheric pressure. In the X-ray irradiator having the above-mentioned structure, a reinforcing plate (3) having a plurality of openings is adhered to at least one surface of the thin film (2), and the irradiation amount of the X-ray (16) is applied to the surface of the irradiation object (8). In order to make uniform, at least one of the thin film (2) and the irradiated body (8) is oscillated in a plane perpendicular to the incident direction of the X-ray (16) during irradiation of the X-ray. An X-ray irradiator, which is configured as follows. 2. The X-ray irradiator according to claim 1,
On the reinforcing plate, there are arranged transmissive window rows (14a1 to 14a) in which rectangular transmissive windows opened to transmit X-rays are arranged in parallel at equal pitches.
a6) are arranged in parallel at equal distances by shifting in one direction along the transmission window rows (14a1 to 14a6) sequentially by two or more rows and a distance that is an integer fraction of the pitch. An X-ray irradiator that is orthogonal to the azimuth direction of the transmission window in the plane of the window and has a reciprocating motion with an amplitude obtained by multiplying the center distance of the row by the integer. 3. The X-ray irradiation apparatus according to claim 2, wherein
In addition to the reciprocating motion according to claim 2, an X-ray irradiating device which performs a reciprocating motion in the column direction having an amplitude exceeding a distance of an integer fraction of the pitch. 4. A thin film (3), which is adhered to a reinforcing plate (3) having a plurality of openings on at least one surface thereof and is provided as a partition wall for maintaining a vacuum between a vacuum X-ray generator and an external atmosphere at atmospheric pressure. The X-ray transmitted through 2) is oscillated on at least one of the thin film (2) and the irradiation object (8) in a plane perpendicular to the incident direction of the X-ray (16), and An X-ray irradiation method, which comprises irradiating the object to be irradiated (8) with a uniform dose of the X-rays (16).