JPH0294428A - X-ray mask structure - Google Patents

Abstract

PURPOSE:To eliminate the change of flatness and parallelism caused by the spreading irregularity of adhesive agent, and obtain an X-ray mask structure excellent in parallelism by bonding a mask holding frame and a reinforcement member, at the part except the boundary surface between the lower surface of the mask retaining frame and the upper surface of the reinforcement member. CONSTITUTION:A desired pattern is formed on an X-ray absorber MP; this absorber MP is retained by a retaining film MM, which is retained by a mask holding frame MF; a reinforcement member MH is arranged on the holding frame MF; thereby constituting an X-ray mask structure. The mask holding frame MF and the reinforcement member MH are bonded at the part except the boundary surface between the lower surface of the mask holding frame MF (the lower surface of resist MG) and the upper surface of the reinforcement member MF, by using adhesive agent MC. A step-difference is formed at a bonding part of the reinforcement member MH to the mask holding frame MF, and the shape of the step-difference is made similar to the outer periphery shape of the mask holding frame MF, thereby eliminating the change of flatness and parallelism caused by spreading irregularity of adhesive agent.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Field of Application) The present invention relates to a mask structure for lithography, and more specifically, provides an X-ray mask structure with excellent f' lineage.

(Prior Art) Conventionally, various methods have been used as a lithographic force method for electronic devices such as ICs and LSIs, and among them, one method, X-ray lithography, is a method that uses high transmittance (low absorption) and Based on its properties such as short wavelength, it has many advantages over conventional lithography methods using visible light and ultraviolet light, and has become a powerful means of submicron lithography. 71: Being noticed.

The mask structure used in one of these X-ray lithography methods is one in which a supporting material (an X-ray transparent material) supporting an X-ray absorbing pattern made of gold or the like is adhesively fixed to a mask holding frame.

Is the support ++a mentioned in (g) supported by a back-etched silicone wafer (mask holding frame), or when handling the mask structure in X-ray exposure equipment such as transportation and storage when using the mask structure described in (g)? Since silicone wafers alone are insufficient in both thickness and strength, reinforcement is usually provided for reinforcement. As these reinforcing bodies, low expansion glass such as Pyrex glass or quartz glass is mainly used.

(Problem to be Solved by the Invention) As a method of joining the reinforcing body to the holding frame, as shown in FIG.
Adhesive M is applied at the interface between the lower surface of F and one surface of reinforcing body MH.
C is bothering me.

Lithography is not limited to X-rays, but also uses a proximity exposure method, and during exposure, a liquid additive, such as a silicone wafer (the surface of which is coated with resist) and a mask structure that holds the mask, is used. It is necessary to set the print gap accurately, usually between 10 and 5
It is required to set the print gap to 0 μm.

The important factor determining this printing gap is that, with reference to FIG. 9, the absorber MP of the mask structure is formed with support lI! 2MM flatness and support 11fi MM
and the back surface of the reinforcing body MH, which is the surface chucked by the exposure device. The 1ω degree of flatness of the X-ray mask is the difference in shrinkage rate due to the t degree of the mask holding frame MF after creating the absorber support membrane MM and the uneven thickness of the adhesive MC between the holding frame MF and the reinforcing body MH. It depends on the deformation of the holding frame MF resulting from. The parallelism of the X-ray mask is determined by the parallelism between the support gMM of the mask holding frame MF that is in close contact with the absorber and the back surface after the support film is formed, and the parallelism between the holding frame MP and the reinforcing body MH. It is determined by the thickness unevenness of the adhesive MC and the parallelism between the surface of the reinforcing body MH that is in close contact with the holding frame MF and the surface on the back side thereof. Therefore, the above mask structure is constructed so that the flatness and parallelism are varied as much as possible, and the absorber, support film, holding frame, and reinforcing body can be formed with high precision through precision processing, but the holding frame and As a result of using an adhesive to bond the reinforcing body, the amount of adhesive present at the interface between the holding frame and the reinforcing body J'
Since it is difficult to define the J-shape accurately, the flatness of the mask structure is set to 1 μm or less, and the parallelism is set to 10
It is difficult to set the distance within μm, and therefore there is a problem that sufficient throughput cannot be obtained. Therefore, the first object of the present invention is to provide a mask structure for X-ray lithography with excellent -F line quality.

(Means for solving problems) The above objects are achieved by the following invention.

That is, the present invention provides an X-ray mask structure comprising a desired pattern of X-ray absorption holes, a support 11 for supporting the absorber, a mask holding frame for supporting these, and a reinforcing body for reinforcing the holding frame. This X-ray mask structure is characterized in that the holding frame and the reinforcing body are bonded to each other at a portion other than the interface between the lower surface of the mask holding frame and the upper surface of the mask holding frame.

(Function) Joins the mask holding frame and reinforcing body of the X-ray mask structure.
By performing this on a part other than the interface between the bottom surface of the mask holding frame and the top surface of the reinforcing body, changes in flatness and parallelism due to uneven application of adhesive are eliminated, and the parallelism is maintained regardless of the amount of adhesive used. An excellent X-ray mask structure is provided.

In addition, even if the thermal expansion of the reinforcing body and the holding frame is different, since the adhesive is not present at the interface between the holding frame and the reinforcing body, problems such as distortion due to the difference in heat field and fleas between the two are also resolved. be done.

(Actual hh Example) Next, the present invention will be explained in more detail by giving 6 preferred examples of fruitfulness.

FIG. 1 is a diagram showing an example of the mask structure of the present invention,
FIG. 2 is a diagram explaining the manufacturing process.

In the figure, MP is an X-ray absorption block, MM is a support supporting the absorber, MF is a mask holding frame supporting the support membrane,
MG indicates a protective film used when etching the mask holding frame while leaving it in a ring shape, MH indicates a reinforcing body, and MC indicates an adhesive. Note that MS is a side groove into which a claw is inserted when mechanically gripping the mask structure, and may or may not be punched depending on the gripping method. Further, 1MA is a notch portion that determines the direction of rotation of the mask structure, and its shape is determined by the positioning mechanism.

The support 11MM used in the configuration of the X-ray mask structure of the present invention as described above is made of beryllium (Be), titanium (
Inorganic materials such as Ti), silicon (Si), boron (B), etc. or their compounds; organic materials such as polyimide, polyamide, polyester, parylene; or composite films of these materials, which are conventionally used as support films. Any of these can be used in the present invention, and these support membranes include
In order to maximize the amount of transmission, the thickness is preferably 0.5 to 5 μm for inorganic films and 1 to 20 μm for organic films. The method of forming these supports 111MM itself may be a conventionally known method. For example, the support 111MM as described above is formed on a silicon wafer (holding frame) MF, and then an etching protective film MG ( The holding frame MF is formed by etching it with a 30% by weight aqueous solution of caustic potassium.
A support membrane MM supported by is formed.

The X-ray absorbing MP formed on the support 111MM is generally made of a material with high density, such as gold, platinum, tungsten, tantalum, copper, nickel, or a thin film of a compound containing them (for example, X-ray mask structures used in conventional X-ray mask structures, such as
Any linear absorbance can be used in the present invention and is not particularly limited.

Such an X-ray absorbing MP is produced by, for example, providing a plating electrode layer on the support 1, patterning a single layer or multilayer resist on it by electron beam writing, and plating it with gold for example. Forms a gold pattern that is resting. Also, support II! Form a film of W, Ta, etc. on 2MM,
An X-ray absorbing MP can be formed by forming a single layer or multilayer resist by electron beam writing, and then plasma etching the W or Ta layer. Alternatively, the X-ray absorbing MP may be formed by back etching a silicon wafer.

The present invention provides a holding frame M for a mask structure constructed as described above.
The reinforcing body MH is attached to F of the holding frame MF (resist M
Adhesive M
It is characterized by adhesion by C.

For the reinforcing body MH used in the present invention, for example, a magnetic material such as low expansion glass such as Pyrex glass or quartz glass, ceramics, iron, nickel, cobalt, or an alloy or compound thereof can be used. These reinforcements MH
It is preferable to have an annular shape similar to the holding frame of the mask structure.

The adhesive MC used to fix the reinforcing body Ml-1 to the holding frame MF is an adhesive with high viscosity and low shrinkage upon curing, such as an epoxy-based, rubber-based, acrylic-based adhesive,
It is preferable to use a thermosetting adhesive such as a polyimide adhesive, a photocuring adhesive, a solvent adhesive, or the like.

The holding frame MH and the reinforcing body MH may be bonded, for example, by bonding the outer peripheral end surface of the mask holding frame MF and the top surface of the reinforcing body MH as shown in FIG. Holding frame MF
The inner end surface of the reinforcing body MH may be bonded to the upper surface of the reinforcing body MH, or
As shown in FIG. 1C, the lower surface of the mask holding frame MF and the inner peripheral end surface of the reinforcing body MH may be bonded together.

The flatness of the mask holding frame MF is equal to or less than the flatness of the silicone wafer used as the mask holding frame MF, which is 1 μm or less, and the stress of the supporting frame MF is 2 to 5 x tensile stress.
By setting 108 dyne/c below, the flatness of the mask holding frame can be made 1 μm or less. According to this embodiment, the reinforcing body MH can be bonded without impairing the flatness of the mask holding frame MF, and the flatness of the X-ray mask to which the reinforcing body MH is bonded can be 1 μm or less.

When the mask holding frame MF has a capacity of 3 μm and the reinforcing body MH has a Y-line capacity of μm, the adhesive J'J
It is possible to manufacture an X-ray mask with a capacity of 8 μm or less (without depending on the size).

Further, the coefficient of thermal expansion of the mask structure does not depend on the reinforcing body MH, but only on the mask holding frame MF.

FIG. 3 is a sectional view of a second embodiment of the invention. The reinforcing body MH has a concave step larger than the outer diameter of the holding frame MF,
By arranging the mask holding frame MF within this step, and not only the outer peripheral end surface of the mask holding frame MF and the upper surface of the reinforcing body MH, but also the inner wall surface of the step of the reinforcing body MH are in contact with each other, the reinforcing body MH and the supporting frame are brought into contact with each other. It is possible to strengthen the adhesion with FM.

FIG. 4 is a sectional view of a third embodiment of the invention. The reinforcing body MH has a step approximately equal to the outer diameter of the holding frame MF, and the mask holding frame MF is inserted into this step to remove the mask holding frame M.
The supporting shaft and the reinforcing body are bonded to each other by the outer peripheral end face of F and the upper surface of the convex portion of the reinforcing body MH. By adhering in this manner, the adhesive is prevented from flowing between the lower surface of the support shaft and the upper surface of the reinforcing body, and the parallelism of the mask structure is ensured.

In addition, as shown in Fig. 5, a notch MA is provided on the reinforcing body MH for use in positioning in the rotational direction when chucking the X-ray mask to the exposure device, and the notch MA is provided on the reinforcing body MH as shown in FIG. The inner wall surface of the mask structure has notch surfaces MB in two perpendicular directions, and the notch MA and the notch surface MB are precisely processed and controlled in the rotational direction. It can be controlled by the notch MA.

FIG. 6 is a sectional view of the fourth embodiment. Similarly to the third embodiment, the reinforcing body MH is provided with a first step MHI having the same shape as the outer diameter of the mask holding frame MF and a second step MHI having a larger diameter.
H2 is provided, the mask holding frame is inserted into the first step,
Adhesive MC is applied between the side surface of the holding frame and the inner surface of the second step.
This further strengthens the adhesion between the holding frame and the reinforcing body.

FIG. 7 is a sectional view of the fifth embodiment. FIG. 8 is a plan view thereof. The reinforcing body MH has a convex portion MH' for three-point positioning in addition to the step for strengthening adhesion. Since the notches MA and MH' used for positioning in the rotational direction are precisely controlled in the rotational direction, the rotational direction of the mask after adhesion can be controlled by the notch MA of the reinforcing body MH.

(Effects of the Invention) According to the present invention as described above, the mask holding frame and the reinforcing body of the X-ray mask structure are joined at a portion other than the interface between the lower surface of the mask holding frame and the upper surface of the reinforcing body. This eliminates changes in flatness and parallelism due to uneven application of adhesive, and provides an X-ray mask structure with excellent flatness and parallelism regardless of the amount of adhesive used.

Further, even if the reinforcing body and the holding frame have different thermal expansions, since no adhesive is present at the interface between the holding frame and the reinforcing body, problems such as distortion due to the difference in thermal expansion between the two can be solved.

In addition, "flatness" used in the present invention refers to the degree of deviation of a flat part from a geometrical plane, and
"Parallelism" means, in a combination of parallel plane parts and flat parts, with one of them as a reference,
It means the amount of deviation of the other plane part from this reference plane.

[Brief explanation of drawings]

1 and 2 are cross-sectional views and configuration diagrams of a first embodiment according to the present invention, FIG. 3 is a cross-sectional view of a second embodiment according to the present invention, and FIG. 4 is a cross-sectional view of a third embodiment according to the present invention. 5 is a plan view of a third embodiment of the present invention, FIG. 6 is a sectional view of a fourth embodiment of the present invention, and FIG. 7 is a fifth embodiment of the present invention. FIG. 8 is a plan view of a fifth embodiment of the present invention, and FIG. 9 is a cross-sectional view of a conventional X-ray mask. MPIX-ray absorption rest MM: Holding I model MF: Support frame
MG Niresist MH = Reinforcement body MC・
Adhesive MS second side/M MA: Notch part diagram (b) (C)! Figure A 5 Figure B Figure 3 Figure Δ (Figure 7 Δ〒5 Figure 3 Figure

Claims (3)

[Claims] (1) In an X-ray mask structure comprising a desired pattern of X-ray absorption holes, a support film that supports the absorption holes, a mask holding frame that supports these, and a reinforcing body that reinforces the holding frame, the mask holding frame and An X-ray mask structure characterized in that the reinforcing body is bonded to a portion other than the interface between the lower surface of the mask holding frame and the upper surface of the reinforcing body. (2) The X-ray mask structure according to claim 1, wherein a step is formed at the holding frame joint portion of the reinforcing body. (3) The X-ray mask structure according to claim 1, wherein the shape of the step of the reinforcing body is similar to the outer peripheral shape of the mask holding frame.