JPH02181907A - X-ray transmitting film holding frame, x-ray mask blank and x-ray mask structure - Google Patents

Abstract

PURPOSE:To easily machine a complicated shape and to enhance a mechanical characteristic and a thermal characteristic by a method wherein a holding frame used to hold an X-ray transmitting film id formed of the following: a holding-frame main body composed of a material whose coefficient of linear expansion is at a specific value or lower; an outer periphery member composed of a material which can be machined easily. CONSTITUTION:As a material for a reinforcement-body main body 4, a ceramic whose coefficient of linear expansion is 1X10<-5>K<-1> or lower is used in order to prevent a strain by heat generated when it is irradiated with X-rays. For example, alumina, Al2O3TiC or the like can be enumerated. As a ceramic sintered substance which can be cut, an AlN-BN-based substance, a silicon carbide-based substance or the like can be enumerated. As an easily machined material which is used to form an outer periphery member 5, a metal or a synthetic resin which can be machined easily with a general lathe or the like is preferable. For example, an iron and steel material, the synthetic resin such as polycarbonate or the like can be enumerated. The main body 4 and the outer periphery member 5 are bonded by an arbitrary method by using an adhesive 3', a screw, a force fit or the like. A side groove 6 for movement use and for hand-fitting use of a mask structure are formed at the outer periphery member 5.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to an X-ray transmitting film holding frame, an X-ray mask blank, and an X-ray mask used in semiconductor manufacturing equipment, particularly an exposure apparatus for performing X-ray exposure. Concerning structures.

(Prior Art) In recent years, with the increasing density and speed of semiconductor integrated circuits, the pattern line width of integrated circuits has tended to be reduced by 70% in about three years.

With further integration of large-capacity memory devices (for example, 4M DRAM), devices with a capacity of 16 Mbit, etc. 5μm
Device design based on rules has begun to take place. For this reason, printing devices are required to have even higher performance, and high performance such that the minimum line width that can be transferred is 0.5 μm or less is beginning to be required. For this reason, steppers using light in the X-ray range (7 to 14) as the exposure light source wavelength are being developed.

The mask structure used in the Kowara X-ray exposure apparatus is
As shown in Figures a and b, an X-ray transparent membrane 2 made of an X-ray transparent material
and a holding frame 4 that holds it under tension.
X-ray absorbers l arranged in a desired geometrical arrangement such as alignment marks are formed on the radiation-transmitting film 21.

The method of forming the X-ray transparent film 2 is roughly classified depending on whether the material used is an organic thin film or an inorganic thin film. The former is selected from a rigid material that has high transmittance for X-rays and is transparent to visible light.Due to its Young's modulus, coefficient of thermal expansion, surface roughness, etc.
Films such as polyamide and mylar are preferably used. These X-ray transparent membranes 11Q2 are held under tension by the adhesive 3 on the holding frame 4, and these X-ray transparent membranes 2 are fixed with sufficient flatness.

On the other hand, when an inorganic material is used as the X-ray transparent membrane 2, as shown in FIGS. A film 2 made of silicon or the like is formed to have a slight tensile stress. Next, silicon wafer 4 on which IIQ2 was deposited
' is removed by etching only the necessary area (area for transmitting X1i1) from the back side, the inorganic thin 11
A mask blank in which Q2 is held under tension on the silicon wafer 4' is obtained. However, in this state, the silicon wafer 4' is thin and has low strength, making it inconvenient to handle and put into practice. It is desirable that the holding frame 4 (FIG. 1) or the reinforcing body 4 (FIG. 3) be sufficiently strong, thermally stable, and lightweight.

Conventionally, quartz glass, borosilicate glass (Pyrex), stainless steel, etc. have been used as materials for forming these materials, but recently ceramic sintered bodies have come to be used because they satisfies the above conditions.

(Problem to be solved by the invention) However, although the above-mentioned quartz glass, borosilicate glass, stainless steel, ceramic materials, etc. are materials with excellent strength and thermal stability, they cannot be easily cut, polished, etc. Processability is poor, especially when machining various complicated shapes around the holding frame and reinforcing body of the mask structure. There is a problem in that it is very difficult to form the positioning notches 7 of the mask structure.

Therefore, an object of the present invention is to solve the problems of the prior art described above,
An object of the present invention is to provide an X-ray transmitting membrane holding frame, an X-ray mask blank, and an X-ray mask structure that can be easily processed into complex shapes and have excellent mechanical and thermal properties.

(Means for resolving the problem) The above [1] is achieved by the following present invention.

That is, the present invention provides a holding frame for holding an X-ray transparent membrane,
An X-ray mask blank consisting of a holding frame holding a radiation-transmitting film, or an X-ray mask blank consisting of an X-ray absorber with a desired pattern, an
In the line mask structure, the holding frame has a linear expansion coefficient of I
X-ray transparent membrane holding frame, X-ray mask blank, and be.

(Function) According to the present invention, the holding frame or the reinforcing body has a linear expansion coefficient of 1
By forming the holding frame main body made of a material of x10-5 or below K-1 and the outer peripheral member made of a material that is easy to machine, it can be easily machined into complex shapes and has excellent mechanical and thermal properties. An X-ray transparent membrane holding frame, an X-ray mask blank, and an X-ray mask structure can be provided.

(Preferred Embodiments) Next, the present invention will be described in more detail by citing preferred embodiments.

The X-ray transparent film 2 used in the configuration of the X-ray mask structure of the present invention is made of inorganic materials such as beryllium (Be), titanium (Ti), silicon (Si), boron (B), etc., or their compounds, etc. Conventional X
! ! Any film used as an il-transmissive membrane can be used in the present invention, and in the case of an inorganic film, the From 5μm to 5μm, in the case of organic matter! to 2
Preferably, the thickness is 0 μm.

The method of forming these X-ray transparent films may be any conventionally known method. For example, if the X-ray transparent rfA2 is an organic material such as polyimide, an organic film may be formed, for example,
It is formed by tensioning and fixing it to a suitable holding frame 4 such as metal, ceramics, or glass using an adhesive 3 (see Figure 1). For example, an X-ray transparent film 2 is formed on the silicon wafer (holding frame) 4', and then an etching protection film (not shown) (polyimide, silicon nitride film, etc.) is provided on the back surface. By etching with a 30% caustic potassium aqueous solution, the inorganic membrane 2 supported on the wafer 4'F can be formed. In this case, since the strength of the silicon wafer 4' is insufficient, it is common to add a reinforcing body 4 made of metal, ceramics, glass, etc. (see FIG. 3).

The X-ray absorber l formed on the X-ray transmitting film 2J is generally a thin film of a material with high density, such as gold, platinum, tungsten, tantalum, copper, nickel, or a compound containing them (for example, Any X-ray absorber used in conventional X-ray mask structures can be used in the present invention, and is not particularly limited.

Such an X-ray absorber 1 is made by, for example, providing a plating electrode layer on the X-ray transparent film 2, patterning a single layer or multilayer resist on the electrode layer by electron beam drawing, and plating with gold, for example. A gold pattern, which is an X-ray absorber, is formed. It is also possible to form a film of W, Ta, etc. on an X-ray transparent film, form a single layer or multilayer resist by electron beam writing, and then plasma-etch the W or Ta layer to form an X-ray absorber. I can do it. Alternatively, the X-ray absorber may be formed before back-etching the silicon wafer.

For adhesion between the X-ray transparent membrane and the holding frame or between the silicon wafer and the reinforcing body, an adhesive that shrinks little when cured, such as
It is preferable to use thermosetting adhesives such as epoxy, rubber, acrylic, and polyimide adhesives, photocuring adhesives, and solvent adhesives.

The present invention provides the structure of the X-ray mask structure as described above, in which the holding frame or the reinforcing body has a linear expansion coefficient of 1 x 10-5K-1'.
It is characterized by consisting of a holding frame (or reinforcing body) main body 4 made of the following materials and an outer peripheral member 5 made of a material that is easy to machine.

The material used for the holding frame main body or reinforcing body main body 4 of the present invention, the holding frame main body or the reinforcing body main body of the mask blank or X-ray mask structure has a linear expansion coefficient of 1 x 10-'
11 or less, and suitable examples include, for example,
Alumina (Al2O2), zirconia (ZrO,),
Cordierite (21g04A120+”5SiO2
), sialon (Si・A1・0・N), silicon carbide (S
iC), aluminum nitride (^IN>), silicon nitride (
SI3N4), other 5iC-ZrB2, ^1,03
-TiC and the like. In addition, as ceramic sintered bodies that can be cut, ^IN-BN series, 5i3N4-B
Examples include N-based, silicon carbide (SiC), and the like.

Among the above ceramics, ceramics having a Young's modulus of 50 GPa or more are particularly preferred for the present invention. More preferably, in order to prevent distortion due to heat generated by X-ray irradiation, ceramics with a linear expansion coefficient of 1 x 10"5K-1 or less are used. Since these ceramics are non-magnetic, This is also preferable in that it does not change the trajectory of the beam.

In the present invention, the Young's modulus and linear expansion coefficient values of preferable ceramic materials are illustrated below.

Pa Vilex 62 Alumina (Al2O2) 370 Zirconia (
ZrO□) 150 cordillite (2
M, qO・2A1203・5SiO2)+10 Sialon (Si・^1・0・N) 270 Silicon carbide (SiC) 400 Aluminum nitride (AIN) 280 Silicon nitride (
SiJ4) 170~300 Si[knee Zr1h 360^1
20:+-Tie 390 ~ 41
0AI20+-TiOz 220AI
N-BN +60 to -1 2,8Xl0-' 7, OX 10-' 10, OxlO-'Xl0-'Xl0-'Xl0-' 1O-6 1O-6 x to-' 1O-6 x to-' l0 -6 Si, N4-[IN 130-1605.
8 to 8.8 Xl0-' The present invention is not limited to the above-mentioned ceramics, and any material having similar physical properties can be used in the present invention.

The ceramics described below can be formed into a desired shape by molding and sintering into a predetermined shape according to a conventional method. In addition, ceramic sintered bodies that can be cut (for example, 81N4N,
5i3N4-BN%5fG), it is possible to mold and bake it into a predetermined shape according to a conventional method, and then perform cutting or the like to obtain the desired dimensional accuracy.

In addition, in the present invention, materials that can be easily machined to be used for forming the outer circumferential member 5 of the holding frame or reinforcing body are preferably metals and synthetic resins that can be easily machined using a numerical lathe, etc. Among these, particularly Specific examples of preferable materials include, for example:
Examples include metal materials such as steel materials, copper alloy materials, aluminum alloy materials, and titanium alloy materials, and synthetic resins such as hard vinyl chloride resin, ABS resin, styrene resin, acrylic resin, and polycarbonate.

In the present invention, the holding frame (reinforcing body) main body 4 and the outer circumferential member 5 are formed from the above-mentioned two types of materials, but the two can be joined by any method such as adhesive 3', screwing, press-fitting, etc. The outer circumferential member 5K is joined by a method to form side grooves 6 for use as hand hooks for movement within the XIL exposure apparatus, such as the one shown in the first drawing, and notches 7 for positioning the mask structure. Such a complex shape can be formed either before or after joining to the main body 4.

The shape of the holding frame and reinforcing body consisting of the main body 4 and the outer circumferential member 5 used in the present invention may be the same as a conventionally known shape, such as a ring shape. It is also possible to fix magnetic material on or inside the frame or reinforcement.

(Example) Next, the present invention will be explained in more detail with reference to Examples.

Example 1 FIG. 1 is a diagram schematically showing a cross section (a) and a bottom surface (b) of a mask structure of this example.

4 in the figure is a ring-shaped mask holding frame body manufactured by pressureless sintering after molding from alumina (Al2O3) ceramics, with an inner diameter of 50 mm, an outer diameter of 60 mm, an inner thickness of 6 mm, and an outer It has a shape with a thickness of 5 mm,
An annular outer circumferential member 5 is bonded to the outside thereof with an adhesive 3'. This annular member is made of 5US304 and has an inner diameter of 60.5 mm, an outer diameter of 100 mm, and an inner thickness of 5 mm.
mm, the outside thickness is 4 mm, and the surrounding gutter 6
and notches 7 are formed by cutting.

The outer circumferential member 5 and the main holding frame body 4 are bonded together using an epoxy brown adhesive 3'.

Reference numeral 2 in the figure is an isotropically stretched polyimide film having a thickness of approximately 7.5 μm, and is fixed to the inclined surface of the holding frame main body 4 with an adhesive 3 such as rubber-based or epoxy-based adhesive.

1 in the figure is gold, which is an X-ray absorber, and has a thickness of approximately 0.7
The μm gold 1 was formed by drawing a resist with an electron beam and then depositing it by electroforming to form a mask pattern (absorber).

Example 2 Alumina (AI20+
) was made of silicon carbide (SjG) and molded using a hot press sintering method, and a mask structure having the same shape as in Example 1 was produced in the same manner as in Example 1, except that an aluminum alloy was used as the outer peripheral member 5.

Embodiment 3 FIG. 2 is a diagram schematically showing a cross section of a mask structure of another embodiment. The materials and shape used are the same as those of the embodiment of FIG. 1, but the holding frame main body 4 and its As shown in the figure, the bonding with the outer circumferential portion 5 is an example in which a step is provided to increase the bonding area to strengthen the bonding.

Embodiment 4 FIG. 3 shows a cross section (a) of a mask structure according to another embodiment of the present invention.
) and the bottom surface (b) schematically.

4 in the figure is a ring-shaped reinforcing body made from machinable IN-BN ceramics (e.g., Tokuyama Soda, Shapal M) after forming and sintering, and has an inner diameter of 60 mm and an outer diameter of 60 mm. It has a diameter of 85 mm, and an annular outer peripheral member 5 is bonded to the outside thereof with an adhesive 3'. This outer peripheral member is made of hard vinyl chloride resin and has an inner diameter of 85 mm.
．． The outer diameter is 100 mm, the thickness is 4 mm, and side grooves 6 and notches 7 are formed around the circumference by cutting. The outer peripheral member 5 and the surface reinforcing body body 4 are bonded together using a polyimide adhesive 3'.

2 in the figure is a silicon nitride film with a thickness of approximately 2 μm formed on a silicone silicon wafer 4', and is fixed to the reinforcing body main body 4 with an adhesive 3 such as an epoxy type via the silicone silicon wafer 4'. .

1 in the figure is gold, which is an X-ray absorber, and has a thickness of approximately 0.7μ.
The gold 1 of m is formed by drawing a resist using an electron beam and then depositing it by electroforming to form a mask pattern.

Example 5 The reinforcing body body 4 of Example 4 was made of 5i3N4BN ceramics (for example, Kawasaki Steel, River Ceram SN).
A mask structure having a similar shape was produced in the same manner as in Example 4 except that acrylic resin was used as the outer circumferential member 5.

All of the mask structures of the present invention obtained above had excellent grain size and processing characteristics.

(Effects) As described above, according to the present invention, the holding frame or the reinforcing body is made of a material having a coefficient of linear expansion of 1×10−′ or less (
(or reinforcing body) An X-ray transmitting body that can be easily machined into complex shapes and has excellent mechanical and thermal properties by being formed from a main body and a peripheral member made of a material that is easy to machine.
Xa mask blanks and X-ray mask structures can be provided.

[Brief explanation of the drawing]

1 to 3 are diagrams schematically showing the mask structure of the present invention. 1: X-ray absorber 2: X-ray transparent membrane 3: Adhesive 3': Adhesive 4: Holding frame (reinforcing body) (main body) 4': Silicon wafer 5: Peripheral member 6: Side groove 7: Notch is patented Applicant Canon Co., Ltd. Agent Patent Attorney Blue 1) Katsuhiro Figure 1 Figure 3 (bJ

Claims (6)

[Claims] (1) In a holding frame for holding an X-ray transparent membrane, the holding frame has a holding frame main body made of a material with a linear expansion coefficient of 1 x 10^-^5 to K^-^1 or less, and is easy to machine. An X-ray transmitting membrane holding frame characterized by comprising a peripheral member made of a material. (2) In an X-ray mask blank consisting of a holding frame holding an X-ray transparent membrane, the holding frame has a linear expansion coefficient of 1×
An X-ray mask blank comprising a holding frame body made of a material of 10^-^5K^-^1 or less and an outer peripheral member made of a material that is easy to machine. (3) In an X-ray mask structure consisting of an X-ray absorber with a desired pattern, an X-ray transparent film that holds the absorber, and a holding frame that holds these, the holding frame has a linear expansion coefficient of 1×10
An X-ray mask structure comprising a holding frame body made of a material of ^-^5K^-^1 or less and a peripheral member made of a material that is easy to machine. (4) The X-ray transparent membrane holding frame, X-ray mask blank, or X-ray mask structure according to any one of claims 1 to 3, wherein the holding frame main body has a Young's modulus of 50 GPa or more. (5) The X-ray transparent membrane holding frame, X-ray mask blank, or
Line mask structure. (6) X according to claims 1 to 3, wherein the holding frame also includes a reinforcing body.
A radiation transmitting membrane holding frame, an X-ray mask blank, or an X-ray mask structure.