JPH0588534B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Field of Application] The present invention is an X-ray exposure mask that is detachably (replaceably) attached to a mask chuck, and a substrate to be exposed is exposed to foreign matter while preventing foreign matter from adhering to the membrane. An object of the present invention is to provide an X-ray exposure apparatus and a method thereof that prevent such problems. [Prior Art] An X-ray exposure mask used in a conventional X-ray exposure apparatus is made by covering a frame material with an X-ray mask supporting lower layer (hereinafter referred to as a membrane) as described in Japanese Patent Publication No. 53-24785. , forming a pattern on the membrane. [Problems to be Solved by the Invention] The above-mentioned conventional technology does not take into account the adhesion of foreign matter to the membrane of the X-ray exposure mask or the mask pattern, resulting in a decrease in yield during exposure (particularly in steppers, the yield is close to zero). ) and that the mask deteriorates due to cleaning with foreign substances. In order to solve the problems of the prior art described above, an object of the present invention is to provide an X-ray mask that is detachably attached to a mask chuck provided at the X-ray emission end of an atmosphere chamber filled with an X-ray transparent gas that does not attenuate X-rays. It is possible to prevent foreign matter from adhering to the membrane of a radiation exposure mask and to prevent the foreign matter from being transferred to the substrate to be exposed, thereby improving the yield in X-ray exposure, as well as preventing the attenuation of X-rays. resolution and high speed
An object of the present invention is to provide an X-ray exposure apparatus and a method thereof, which can realize radiation exposure and further increase the service life (life) of the X-ray exposure mask by reducing the number of times the X-ray exposure mask is washed. . [Means for Solving the Problems] In order to achieve the above object, the present invention provides an X-ray source, allows X-rays from the X-ray source to enter through a transmission window, and generates X-rays that do not attenuate the X-rays. An atmosphere chamber filled with a permeable gas is provided, a mask chuck is provided at the X-ray emission end of the atmosphere chamber, and a support frame is provided on the side of the mask chuck opposite to the substrate to be exposed around the membrane on which the circuit pattern is formed. A thin film that transmits X-rays is provided at a desired distance from the membrane on the side of the mask chuck opposite to the substrate to be exposed to prevent foreign matter from entering the space between the thin film and the membrane. An X-ray exposure mask, which is sealed from the outside air and further filled with an X-ray transparent gas that does not attenuate X-rays in the space, is attached to the mask chuck, and the
X-rays from a radiation source are incident on the atmospheric chamber through the transmission window, and the X-rays irradiated through the atmospheric chamber are transmitted through a thin film of an X-ray exposure mask attached to the mask chuck to prevent the presence of foreign matter and the X-rays. A circuit pattern formed on the membrane by irradiating the membrane through a space filled with an X-ray transparent gas that does not attenuate the radiation is placed opposite to the circuit pattern of the X-ray exposure mask with a minute gap formed therein. This is an X-ray exposure apparatus characterized in that it is configured to perform exposure transfer onto a substrate. Further, the present invention is characterized in that, in the X-ray exposure apparatus, the X-ray exposure mask is configured to be attached to the mask chuck in a state in which the X-ray transparent gas is enclosed. Further, the present invention is characterized in that the X-ray exposure mask in the X-ray exposure apparatus is configured by attaching the frame on which the thin film is stretched by adhering to the support frame. Further, the present invention supports the surface of the membrane on the side of the mask chuck opposite to the substrate to be exposed around the membrane on which the circuit pattern is formed by a support frame, and the membrane is spaced a desired distance from the side of the mask chuck opposite to the substrate to be exposed. A thin film that transmits X-rays is provided, the space between the thin film and the membrane is sealed from the outside air to prevent foreign matter from entering, and the space is further filled with an X-ray-transparent gas that does not attenuate X-rays. Prepare the configured X-ray exposure mask, and place the prepared X-ray exposure mask with a transmission window on the incident side.
It is attached to a mask chuck provided at the X-ray output end of an atmosphere chamber filled with an X-ray transparent gas that does not attenuate the radiation, and X-rays from the X-ray source are incident on the atmosphere chamber through the transmission window and the atmosphere is X-rays irradiated through the chamber are irradiated onto the membrane through a thin film of an X-ray exposure mask attached to the mask chuck and through a space filled with an X-ray transparent gas that is free of foreign matter and does not attenuate the X-rays. This is an X-ray exposure method characterized in that the circuit pattern formed in the X-ray exposure mask is exposed and transferred onto a substrate to be exposed which is placed opposite to the circuit pattern of the X-ray exposure mask by forming a minute gap therebetween. Further, the present invention is characterized in that, in the X-ray exposure method, the X-ray exposure mask is attached to the mask chuck in a state in which the X-ray transparent gas is enclosed. [Function] With the above configuration, the X-ray exposure mask attached to the mask chuck provided at the X-ray output end of the atmosphere chamber filled with an X-ray transparent gas that does not attenuate X-rays can be attached to a membrane formed with a circuit pattern. A thin film that transmits X-rays is provided at a desired distance from the membrane on the side of the mask chuck opposite to the substrate to be exposed, with the surface of the mask chuck opposite to the substrate to be exposed around the membrane being supported by a support frame. The space between the thin film and the membrane is sealed from the outside air to prevent foreign matter from entering, and the space is further sealed with X.
Since the structure is filled with an X-ray transparent gas such as He that does not attenuate the rays, it prevents foreign matter from adhering to the membrane and allows it to adhere only to the thin film. By preventing the above-mentioned foreign matter from being exposed and transferred onto the substrate to be exposed, it is possible to improve the yield in X-ray exposure, and to prevent the attenuation of X-rays, realizing high-resolution and high-speed X-ray exposure. The service life of X-ray exposure masks can be extended by reducing the number of times they are washed.
It is possible to increase the amount of [Example] Hereinafter, an example of the present invention will be described with reference to FIG. In an X-ray exposure mask, a Si frame 2 with a mask membrane 1 stretched thereon, a support frame 3 made of Virex bonded to the Si frame 2, a metal frame 5 bonded to the support frame 3 with double-sided tape 4, and a metal frame 5 bonded to the metal frame 5. The basic structure is the thin film 6. Further, the metal frame 5 has a hole 7 for injecting He, a screw 8 for peeling off the metal frame, and a cover 9 for these. Further, a filter 10 is provided in the He injection hole 7. Also, drain hole 11 of He
is provided on the support frame 3, and is covered with a lid 12. The method and operation of assembling the X-ray exposure mask having the above structure will be explained below. in clean air,
A metal frame 5 covered with a thin film 6 is adhered to a virex frame 3 of an X-ray exposure mask with double-sided tape 4. At this time, the cover 9 and the lid 12 are removed. Prepare separately
He injection device (can be easily designed by the engineer concerned).
Not shown. ), He gas is gradually injected from the He injection hole 7 so as not to damage the membrane 1 and the thin film 6. At this time, the filter 10 prevents foreign matter from entering. The mixture ratio of the drained He and air is monitored, and when a sufficient He atmosphere (approximately 99% or more) is formed in the closed space 13, the cover 9 and lid 12 are closed. the assembly work itself
If it is performed in He gas, He injection work and injection-related structures are not required. It is desirable to handle the mask assembled as described above with the thin film 6 facing upward. This is because the foreign matter 20 usually adheres from above, and natural adhesion from below is extremely rare. An X-ray exposure mask constructed as described above was manufactured in a patent application filed in 1983.
When attached to the mask chuck of an X-ray exposure device having a He chamber, as shown in No. 54429,
The throughput can be improved as follows. That is, when exchanging the X-ray exposure mask from the mask chuck, the time for replacing the air near the mask chuck and in the frames 2 and 3 of the mask with He can be extremely shortened, and the time for exchanging the mask is shortened. Ru. The above structure shown in FIG. 1 can prevent foreign matter from adhering to the mask membrane.
Also, the thin film will need to be replaced due to deterioration due to X-rays, adhesion of foreign substances, or mechanical damage. In this case, remove the cover 9 (using the set screw 14 shown in FIG. Peel it off from frame 3. Vacuum grease 15 is applied to the head of the screw 8 to prevent foreign matter generation and He leakage.
Thereafter, a new set of metal frame 5 and thin film 6 may be assembled to the support frame 3 in a clean atmosphere. FIG. 2 is a plan view of one embodiment (FIG. 1) according to the present invention. There are three He injection holes 7 and three drain holes 11, but any number may be used as long as He exchange is possible. Cover 9 has He injection hole 7,
The peeling screws 8 are common and are fixed to the metal frame 5 by 143 setscrews, but the bottom line is that the cover 9 can be fixed in any way as long as it prevents He from flowing out from the He injection hole 7. Further, the drain 11 may be provided not on the support frame 3 but on the metal frame 5. Alternatively, the thin film 6 may be attached directly to the support frame 3 as shown in FIG. The X-ray exposure mask integrally constructed as shown in FIG. 3 is attached to the mask chuck 24 so as to be replaceable. The conditions of the thin film will be explained below with reference to FIG. The foreign object 20 on the thin film 6 forms a blurred image on the wafer 22 due to the size d of the X-ray source 21 and the penumbra blur B caused by the gap G between the thin film 6 and the wafer 22. That is, B=d/lXG (1) The penumbra blur B becomes the maximum value at which the foreign object 20 is not imaged on the wafer 22, but even if no image is formed, the contrast of the circuit pattern under the foreign object 20 is reduced, so
The allowable value R of the foreign matter 20 is tentatively determined as follows. R=B/2 (2) If conditions are given using equations (1) and (2), the position of the thin film 6 is determined. Now, assume the following conditions. Diameter of X-ray source d = 1 mm Between X-ray source 21 and thin film 6 L = 200 mn Allowable size of foreign object 20 R = 5 μm Penumbra blur B = 10 μm from formula (2), thin film 6 from formula (1)
The distance G between the wafer 22 and the wafer 22 is 2 mm. From the above, G is 2mm
It turns out that more is better. Since the thickness of the mask is usually 2 to 5 mm, it is sufficient to place the thin film 6 on the top of the mask. Next, the physical properties of the thin film 6 will be explained. The membrane 6 must firstly be transparent to the X-rays 26. Specifically, a transmittance of about 90% or more is required. Next, alignment detection must be possible, and in detection using the objective lens 23 as shown in FIG. 3 or similar light 27, it is necessary to transmit the detection light (approximately 95% or more). Further, it is necessary to be optically uniform within the detection area. Also, in terms of strength (durability), it needs to be stronger than the mask membrane 1. If it is weak, the life of the mask will be determined by the thin film. Also, closed space 1
If the X-ray exposure mask injected with He in No. 3 is an
In the state where the thin film 6 is attached by adsorption, the He atmosphere 25 is also present above the thin film 6. Further, in the same invention, an atmospheric atmosphere 26 exists between the membrane 1 and the wafer 22.
Since He permeates through the thin film 6 and membrane 1 to some extent, in order to maintain the sealed space 13 in a He atmosphere, the amount of He permeated through the thin film 6 must be made smaller than that through the membrane 1, or the injection hole 28 as shown in FIG. and drain 2
There is a method in which He is injected into the space 13 little by little using 9. The drain 29 is not necessary if the He injection hole 28 is sufficiently large or has a plurality of holes to allow natural ventilation. Possible materials for the thin film 6 that satisfy the above properties include organic films such as nitrocellulose (2 μm), vinylidene chloride (1 to 2 μm), and PIQ (1 μm). Of course, as long as the conditions are met, an inorganic film or an organic/inorganic synthetic film may be used. FIG. 4 shows a case 30 in which masks are stored while maintaining a He atmosphere inside the closed space 13.
By injecting He through the He injection hole 31 or by setting the mask 32 in a He atmosphere and closing the lid 33, the partial pressure of He in the sealed space 13 due to He leaking from the thin film 6 or membrane 1 explained in FIG. Prevent decline. Therefore, once set, it must be completely sealed. Another embodiment will be explained with reference to FIG. The volume of the closed space 13 changes by ΔV due to temperature fluctuation ΔT°C. If the volume of the sealed space 13 is V and the operating temperature is T°C, then ΔV=ΔT/273+T×V (3) If the sealed space 13 is now diameter D and height h, then V=(D/2) ² π× h (4) T=24℃, D=40mm, h=5mm, ΔT=±0.5℃
Then, from equation (4), V=6283mm ³ , and from equation (3), ΔV
= ± ^10mm3 . Now, assuming that the stiffness ratio of the membrane 1 and the thin film 6 is B, the amount of vertical movement of each membrane due to the volume change ΔV can be approximated by dividing the change Δh in height h by the stiffness ratio B. Δh=h×ΔT/273+T (5) From equation (5), Δh=±8.4 μm. If we try to keep the vertical amount of the membrane within ±0.4 μm, the stiffness ratio B=8.4/0.4=21. In reality, ΔT can be suppressed to ±0.2°C, so the stiffness ratio B is 8.4 according to the above calculation, which is fully achievable. As an alternative method, as shown in FIG. 5, if a pressure adjustment hole 40 with a diameter of a is provided and an adjustment membrane 41 is provided in the pressure adjustment hole 40, if the adjustment membrane 41 is provided, the vertical amount of the adjustment membrane 41 ±C It is conceivable that the volume change ΔV due to the temperature fluctuation ΔT of the closed space 13 can be absorbed by. Adjustment hole 40
Suppose there are N pieces. The vertical amount C is

〔Effect of the invention〕

According to the present invention, an X-ray exposure mask attached to a mask chuck provided at the X-ray output end of an atmosphere chamber filled with an X-ray transparent gas that does not attenuate X-rays is connected to a membrane formed with a circuit pattern. The surface on the side of the mask chuck opposite to the surrounding substrate to be exposed is supported by a support frame, and a thin film that transmits X-rays is provided at a desired distance from the membrane on the side of the mask chuck opposite to the substrate to be exposed. The space between the
Since the structure satisfies the expectation of X-ray transmission such as He that does not attenuate rays, it prevents foreign matter from adhering to the membrane and allows it to adhere only to the thin film, thereby eliminating foreign matter on the thin film through penumbra blur or diffraction effects. It prevents the foreign matter from being transferred onto the substrate to be exposed by exposure, allowing foreign matter on the thin film to be tolerated up to a few micrometers, and also makes it possible to prevent foreign matter through which X-rays can pass through.
It eliminates defective line widths due to line contrast deterioration, improves yield especially in step-and-repeat X-ray exposure, prevents X-ray attenuation, and realizes high-resolution and high-speed X-ray exposure.
It is possible to increase the service life (lifetime) of the X-ray exposure mask by reducing the number of times the X-ray exposure mask is washed, and it has the effect of reducing the cost of expensive X-ray masks to less than 1/10. .

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing one embodiment of the present invention, and FIG.
The figure is a plan view showing one embodiment of the present invention, FIG. 3 is a diagram explaining the principle and details of the present invention, FIG. 4 is a sectional view showing another embodiment of the present invention, and FIG. FIG. 6 is a sectional view showing still another embodiment of the invention, FIG. 7 is a sectional view showing still another embodiment of the invention. DESCRIPTION OF SYMBOLS 1... Membrane, 3... Support frame, 5... Metal frame, 6... Thin film, 20... Foreign matter, 21... X-ray source, 22... Wafer, 26... X-ray.

Claims (1)

[Claims] 1. An X-ray source is provided, an atmospheric chamber is provided in which X-rays from the X-ray source are incident through a transmission window, and an X-ray transparent gas that does not attenuate the X-rays is filled; A mask chuck is provided at the X-ray emission end, and the side of the mask chuck opposite to the exposed substrate surrounding the membrane on which the circuit pattern is formed is supported by a support frame, and the membrane is placed opposite to the exposed substrate. A thin film that transmits X-rays is provided at a desired distance on the mask chuck side of the mask, and the space between the thin film and the membrane is sealed from the outside air to prevent foreign matter from entering.
An X-ray exposure mask filled with an X-ray transparent gas that does not attenuate radiation is attached to the mask chuck, and X-rays from the X-ray source are incident on the atmosphere chamber through the transmission window and irradiated through the atmosphere chamber. X-rays formed on the membrane are irradiated with the X-rays through the thin film of the X-ray exposure mask attached to the mask chuck and through a space filled with an X-ray transparent gas that is free of foreign matter and does not attenuate the X-rays. 1. An X-ray exposure apparatus characterized in that the X-ray exposure apparatus is configured to expose and transfer a circuit pattern formed on the X-ray exposure mask onto a substrate to be exposed, which is placed opposite to the circuit pattern of the X-ray exposure mask with a minute gap formed therebetween. 2. The X-ray exposure apparatus according to claim 1, wherein the X-ray exposure mask is configured to be attached to the mask chuck in a state in which the X-ray transparent gas is enclosed. 3. The X-ray exposure apparatus according to claim 1, wherein the X-ray exposure mask is constructed by attaching a frame on which the thin film is stretched by adhering it to the support frame. 4. Support the surface of the membrane on which the circuit pattern is formed on the side of the mask chuck opposite to the substrate to be exposed with a support frame, and apply X-rays at a desired distance from the membrane to the side of the mask chuck opposite to the substrate to be exposed. A thin film that transmits X-rays is provided, the space between the thin film and the membrane is sealed from the outside air to prevent foreign matter from entering, and the space is further filled with an X-ray-transparent gas that does not attenuate the X-rays. An exposure mask is prepared, and the prepared X-ray exposure mask is placed in an atmosphere chamber filled with an X-ray transparent gas that has a transmission window on the incident side and does not attenuate X-rays.
The X-rays from the X-ray source are incident on the atmosphere chamber through the transmission window, and the X-rays irradiated through the atmosphere chamber are transmitted to the X-rays attached to the mask chuck. The circuit pattern formed on the membrane by irradiating the membrane through the thin film of the exposure mask through a space filled with an X-ray transparent gas that is free of foreign matter and does not attenuate the X-rays is the circuit pattern of the X-ray exposure mask. An X-ray exposure method characterized by exposing and transferring onto a substrate to be exposed facing each other with a minute gap formed therebetween. 5. The X-ray exposure mask according to claim 4, wherein the X-ray exposure mask is attached to the mask chuck in a state in which the X-ray transparent gas is enclosed.
Line exposure method.