JP2001110715A - Mask for x-ray exposure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent deterioration of adhesive strength which is to be caused by chemical liquid when a mask wafer for X-ray exposure is stuck to a mask frame by using ultraviolet-curing resin and epoxy resin as adhesive agent, regarding a mask for x-ray exposure. SOLUTION: Trenches 3 for elastic packing material are formed at least inside the surface of a sticking surface side to a mask wafer 1 for X-ray exposure, out of surfaces of a mask frame 2. Elastic packing material 5 is accommodated in the trenches 3, and adhesive agent 7 is applied outside the trenches 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an X-ray exposure mask and, more particularly, to a method for preventing a decrease in adhesive strength due to a chemical solution when an X-ray exposure mask and a mask frame are bonded using an adhesive. The present invention relates to an X-ray exposure mask having a characteristic in the configuration for performing the above.

[0002]

2. Description of the Related Art With the recent miniaturization of semiconductor devices, X-ray exposure using X-rays as light having a shorter wavelength in place of ultraviolet exposure has been developed, and an X-ray mask used for such X-ray exposure has been developed. A heavy metal film such as Ta or W is used as an absorber, and various methods such as a back etching type and a back etching preceding type have been tried as manufacturing methods.

[0003] Among them, the back-etching type, in which the absorber is patterned after the back-etching step, is free from the influence of the membrane stress and the distortion due to the adhesion of the mask frame, and has improved positional accuracy as compared with the back-etching type. There is a feature.

[0004] In such a manufacturing method of the back etching precedent type, the bonding method for bonding the mask wafer for X-ray exposure and the mask frame includes a bonding method using alloy bonding, a bonding method using anodic bonding, ultraviolet curing. An adhesion method using a mold resin as an adhesive, an adhesion method using an epoxy resin as an adhesive, and the like have been proposed.

[0005] Among them, the bonding method by alloy bonding is 50
A high bonding temperature of 0 ° C. or higher is required, which has a problem of adversely affecting the X-ray absorber film. That is, there is a problem that the X-ray absorber film causes a stress fluctuation at a high temperature of 500 ° C. or more, and causes mask distortion.

[0006] In the bonding method utilizing anodic bonding,
There is a problem that the mask frame is limited to a special mask frame such as one containing a Na element as a component, and also requires several hours of bonding time.

On the other hand, in the case of a bonding method using an ultraviolet-curing resin or an epoxy resin as an adhesive, bonding can be performed at a low temperature of 200 ° C. or less, and bonding can be performed in a short time. There are advantages.

[0008]

However, in the case of the bonding method using an ultraviolet-curing resin or an epoxy resin as an adhesive, a mask cleaning process using a sulfuric acid-hydrogen peroxide mixture or a silicon cleaning using a hydrofluoric nitric acid or the like is performed. At the time of the back surface etching process, there is a problem that these adhesives are weak to chemicals such as sulfuric acid-hydrogen peroxide or hydrofluoric-nitric acid used in the process and the adhesive strength is reduced.

Therefore, the present invention prevents a decrease in the adhesive force due to a chemical solution when an X-ray exposure mask wafer and a mask frame are bonded to each other by using an ultraviolet curable resin or an epoxy resin as an adhesive.

[0010]

FIG. 1 is a block diagram showing the principle of the present invention, and means for solving the problems in the present invention will be described with reference to FIG. FIG. 1 is a schematic sectional view of an X-ray exposure mask. See FIG. 1 (1) In the present invention, in an X-ray exposure mask, an elastic packing material groove 3 is provided on the surface of the mask frame 2 and at least inside the surface on the bonding surface side with the X-ray exposure mask wafer 1. At the same time, the elastic packing material 5 is housed in the elastic packing material groove 3 and the adhesive 7 is provided outside the inner elastic packing material groove 3.

As described above, the grooves 3 for the elastic packing material are provided on the surface of the mask frame 2 and at least inside the surface on the side of the bonding surface with the mask wafer 1 for X-ray exposure.
When the elastic packing material 5 is accommodated in the elastic packing material groove 3 and the adhesive 7 is provided outside the inner elastic packing material groove 3, an etching solution such as KOH is used to etch the adhesive 7 during silicon back surface etching. Since it does not penetrate to the maximum, the adhesive strength does not decrease. In addition,
When accompanied by mask cleaning using a chemical solution such as sulfuric acid peroxide,
It is preferable that the elastic packing material groove 4 is also provided outside the adhesive 7 and the elastic packing material 6 is accommodated in the elastic packing material groove 4.

(2) Further, according to the present invention, in the above (1), the elastic packing members 5, 6 are made of either an O-ring or an elastic sheet, and have chemical resistance and 25%.
It is characterized by having heat resistance to withstand a temperature of 0 ° C.

As described above, the elastic packing materials 5 and 6 are made of O
Either a ring or an elastic sheet may be used, and in any case, chemical resistance to withstand the chemical used in the silicon back surface etching process and mask cleaning process, and heat resistance to withstand the temperature of 250 ° C. that can withstand the bonding temperature at the time of bonding. It is sufficient if it has.

(3) The present invention is characterized in that in the above (1) or (2), the adhesive 7 is made of either an epoxy resin adhesive sheet or an ultraviolet curable resin adhesive sheet. .

As described above, it is desirable to use either a sheet-like epoxy resin adhesive sheet or an ultraviolet-curable resin adhesive sheet as the adhesive 7 in order to improve workability when the adhesive 7 is provided. . In this case, the position where the adhesive 7 is provided on the side of the mask frame 2 to be bonded to the mask wafer 1 for X-ray exposure so that the bonding surface becomes flat during bonding and the adhesive 7 does not flow around. It is desirable to provide a groove for the adhesive.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A manufacturing process according to a first embodiment of the present invention will now be described with reference to FIGS. Referring to FIG. 2A, first, for example, a 2.0 μm thick SiC film 12 is formed on both surfaces of a silicon wafer 11 having a thickness of 2 μm by a CVD method using dichlorosilane and acetylene as source gases. 13 is deposited. In this case, the upper S
The iC film 12 becomes a membrane film.

Referring to FIG. 2B, a resist pattern (not shown) having a window pattern to be an X-ray exposure area is formed on the backside SiC film 13 by a photolithography process, and this resist pattern is used as a mask. An opening 14 is provided in a region corresponding to the X-ray exposure region of the SiC film 13 by performing dry etching.

Referring to FIG. 2C, a Ta film 1 serving as an X-ray absorber film is formed on the SiC film 12 on the front surface serving as a membrane film by sputtering.
5 is deposited to a thickness of, for example, 0.4 μm, and then annealed at a temperature of, for example, 300 ° C. to obtain X.
The stress correction of the Ta film 15 serving as the line absorber film is performed.

Next, as shown in FIG. 2D, the SiC mask frame 16 having a thickness of, for example, 4 mm is bonded to the surface of the SiC mask frame 16 with the mask wafer for X-ray exposure. The O-ring grooves 17 and 18 having a depth of 1.8 mm are provided.
For example, an adhesive groove 19 having a width of 10 mm and a depth of 15 μm is provided.
For example, 2 mm O-rings 20 and 21 are fitted, and an adhesive sheet 22 made of, for example, an epoxy resin having a thickness of 20 μm is attached in the adhesive groove 19.

In this case, the O-rings 20 and 21 are made of a cleaning solution such as a sulfuric acid peroxide solution or an ammonia peroxide solution used in a mask cleaning process and an etching solution such as hydrofluoric nitric acid or KOH used in a silicon back surface etching process. As long as it has chemical resistance to withstand heat and heat resistance to withstand a temperature of 250 ° C., for example, Kalrez (trade name, manufactured by DuPont) is used.

Referring to FIG. 3E, the adhesive sheet 22 and the O-rings 20, 2
The mask frame 16 provided with 1 is opposed to the back side of the mask wafer for X-ray exposure, for example, with a weight of about 5 kg being applied, and heat-treated at 200 ° C. for 5 minutes for bonding. In this case, the adhesive groove 19
Is provided, when bonded, the mask wafer for X-ray exposure and the mask frame 16 come into close contact with no gap over the entire surface, and the adhesive does not flow out.

Next, as shown in FIG. 3F, the silicon wafer 11 is etched from the back side using KOH as an etching
The C film 12 is exposed. In this silicon rear surface etching step, the KO is formed by the O-ring 21 provided inside.
Since H is prevented from penetrating to the adhesive sheet 22, the adhesive sheet 22 is not eroded by KOH and the adhesive strength is not reduced. The exposed part of the SiC film 12 becomes the membrane region 23.

Next, a resist pattern (not shown) for forming an X-ray absorber pattern is formed on the surface side of the SiC film 12 by an electron beam exposure method, and this resist pattern is masked. The basic structure of an X-ray exposure mask can be obtained by etching the Ta film 15 by performing dry etching and forming the X-ray absorber pattern 24.

Next, although not shown, the X-ray exposure mask formed as described above is subjected to mask cleaning using sulfuric acid and hydrogen peroxide as a cleaning solution to finally complete the X-ray exposure mask. I do. In this mask cleaning step, the O-ring 20 provided on the outside prevents the sulfuric acid peroxide from penetrating to the adhesive sheet 22, so that the adhesive sheet 22 is eroded by the sulfuric acid peroxide and the adhesive strength is reduced. Never do.

As described above, in the first embodiment of the present invention, since the two O-rings 20 and 21 having chemical resistance are used and the adhesive is provided therebetween, the silicon back surface etching step and In the mask cleaning process, the adhesive sheet 22 is not exposed to the etching liquid or the cleaning liquid, so that the adhesive strength of the adhesive sheet 22 can be prevented from being reduced. 16 can be maintained in a good state.

In the first embodiment, an epoxy resin capable of bonding the mask wafer for X-ray exposure and the mask frame at a heating temperature of about 200 ° C. is used as the adhesive. Since it is used, the Ta film 1
5 does not cause stress fluctuation.

Next, a second embodiment of the present invention will be described with reference to FIG. 4. In the first embodiment of the present invention, the O-ring in the first embodiment is used. Is replaced by an elastic sheet. Referring to FIG. 4 (a), the thickness is set to be exactly the same as in the first embodiment.
For example, a 2.0 μm-thick SiC film 12 is formed on both surfaces of a 2 μm silicon wafer 11 by a CVD method using dichlorosilane and acetylene as a source gas.
After depositing the resist pattern 13, a resist pattern (not shown) having a window pattern to be an X-ray exposure area is formed on the backside SiC film 13 by a photolithography process, and dry etching is performed using the resist pattern as a mask. By performing this, an opening 14 is provided in a region of the SiC film 13 corresponding to the X-ray exposure region.

Next, a Ta film 15 serving as an X-ray absorber film is deposited to a thickness of, for example, 0.4 μm on the SiC film 12 on the surface side serving as the membrane film by using a sputtering method. By annealing at a temperature of 300 ° C., stress correction of the Ta film 15 which becomes the X-ray absorber film is performed.

Next, referring to FIG. 4B, the mask frame 16 made of SiC having a thickness of, for example, 4 mm and having a width of, for example, 4.8 mm on the surface on the bonding surface side with the mask wafer for X-ray exposure. The elastic sheet grooves 25 and 26 having a depth of 0.8 mm are provided, and between them, for example, an adhesive groove 19 having a width of 8 mm and a depth of 15 μm is provided. In 26,
For example, elastic sheets 27 and 28 each having a width of 4 mm and a thickness of 1.0 mm are fitted, and an adhesive sheet 22 made of, for example, a 20 μm-thick epoxy resin is inserted into the adhesive groove 19. paste.

In this case, the elastic sheets 27, 28
It has a chemical resistance that can withstand a cleaning solution such as a sulfuric acid peroxide solution or an ammonia peroxide solution used in a mask cleaning process and an etching solution such as hydrofluoric nitric acid or KOH used in a silicon back surface etching process, and 250 What is necessary is just to have the heat resistance which can withstand the temperature of ° C, for example, should just be comprised with a fluororesin.

Next, as in the first embodiment, the mask frame 16 provided with the adhesive sheet 22 and the elastic sheets 27 and 28 and the mask wafer for X-ray exposure are thereafter used as in the first embodiment. Are bonded to each other by heating them at 200 ° C. for 5 minutes in a state in which a back side of each is facing, for example, a weight of about 5 kg is applied. Also in this case, since the adhesive groove 19 is provided, when bonding, the mask wafer for X-ray exposure and the mask frame 16 come into close contact with no gap over the entire surface, and the adhesive may flow out. Absent.

Next, as shown in FIG. 4D, the silicon wafer 11 is etched from the back side using KOH as an etching solution, thereby
After the C film 12 is exposed, S
A resist pattern (not shown) for forming an X-ray absorber pattern is formed on the front surface side of the iC film 12, and the Ta film 15 is etched by performing dry etching using the resist pattern as a mask, thereby forming an X-ray. By forming the absorber pattern 24, the basic structure of the X-ray exposure mask can be obtained.

Next, although not shown, the X-ray exposure mask thus formed is subjected to mask cleaning using sulfuric acid and hydrogen peroxide as a cleaning solution, thereby finally completing the X-ray exposure mask. I do.

Also in the second embodiment, in the silicon back surface etching step, KOH is prevented from penetrating to the adhesive sheet 22 by the elastic sheet 28 provided on the inner side. KOH
In addition, in the mask cleaning step, the elastic sheet 27 provided on the outside prevents the sulfuric acid-hydrogen peroxide from penetrating to the adhesive sheet 22. The adhesive sheet 22 is not eroded by the sulfuric acid / hydrogen peroxide mixture, so that the adhesive strength is not reduced. Therefore, the adhesive state between the mask wafer for X-ray exposure and the mask frame 16 can be kept good. Other functions and effects are the same as those of the first embodiment.

Next, a third embodiment of the present invention will be described with reference to FIG. 5. In the third embodiment of the present invention, the epoxy resin according to the first embodiment is used. Is replaced by an ultraviolet-curable resin adhesive sheet. Referring to FIG. 5 (a), first, the thickness is exactly the same as in the first embodiment.
For example, a 2.0 μm-thick SiC film 12 is formed on both surfaces of a 2 μm silicon wafer 11 by a CVD method using dichlorosilane and acetylene as a source gas.
After depositing the resist pattern 13, a resist pattern (not shown) having a window pattern to be an X-ray exposure area is formed on the backside SiC film 13 by a photolithography process, and dry etching is performed using the resist pattern as a mask. By performing this, an opening 14 is provided in a region of the SiC film 13 corresponding to the X-ray exposure region.

Next, a Ta film 15 serving as an X-ray absorber film is deposited to a thickness of, for example, 0.4 μm on the SiC film 12 on the front surface serving as a membrane film by sputtering, and then, for example, By annealing at a temperature of 300 ° C., stress correction of the Ta film 15 which becomes the X-ray absorber film is performed.

Next, as shown in FIG. 5 (b), the SiC mask frame 16 having a thickness of 4 mm, for example, has a width of 2.5 mm on the surface on the bonding surface side with the mask wafer for X-ray exposure. The O-ring grooves 17 and 18 having a depth of 1.8 mm are provided.
For example, an adhesive groove 19 having a width of 10 mm and a depth of 15 μm is provided.
For example, 2 mm O-rings 20 and 21 are fitted, and an ultraviolet curable resin adhesive sheet 29 having a thickness of, for example, 20 μm is adhered into the adhesive groove 19.

Also in this case, the O-rings 20 and 21 are made of a cleaning solution such as a sulfuric acid peroxide solution or an ammonia peroxide solution used in a mask cleaning process, and an etching solution such as hydrofluoric nitric acid or KOH used in a silicon back surface etching process. As long as it has chemical resistance to withstand heat and heat resistance to withstand a temperature of 250 ° C., for example, Kalrez (trade name, manufactured by DuPont) is used.

Next, as shown in FIG. 5 (c), the ultraviolet curable resin adhesive sheet 29, the mask frame 16 provided with the O-rings 20 and 21, and the back side of the mask wafer for X-ray exposure are opposed to each other. Under the condition that a certain degree of load is applied, the UV-curable resin adhesive sheet 29 is irradiated with UV light at 150 ° C. for 30 minutes to cure the UV-curable resin adhesive sheet 29 to perform the bonding. Also in this case, since the adhesive groove 19 is provided, when bonding, the mask wafer for X-ray exposure and the mask frame 16 come into close contact with no gap over the entire surface, and the adhesive may flow out. Absent.

Next, as shown in FIG. 5 (d), the silicon wafer 11 is etched from the back side using
After the C film 12 is exposed, S
A resist pattern (not shown) for forming an X-ray absorber pattern is formed on the front surface side of the iC film 12, and the Ta film 15 is etched by performing dry etching using the resist pattern as a mask, thereby forming an X-ray. By forming the absorber pattern 24, the basic structure of the X-ray exposure mask can be obtained.

Next, although not shown, the X-ray exposure mask formed as described above is subjected to mask cleaning using sulfuric acid and hydrogen peroxide as a cleaning solution to finally complete the X-ray exposure mask. I do.

Also in the third embodiment, the O-ring 21 provided inside prevents the KOH from penetrating to the ultraviolet-curable resin adhesive sheet 29 in the silicon back surface etching step. The mold resin adhesive sheet 29 is not eroded by KOH, and the adhesive strength is not reduced. Further, in the mask cleaning step, the O-ring 20 provided on the outside causes the sulfuric acid / hydrogen peroxide to cure the ultraviolet curable resin adhesive sheet 29. As a result, the UV-curable resin adhesive sheet 29 is not eroded by the sulfuric acid peroxide and the adhesive strength is not reduced, thereby bonding the X-ray exposure mask wafer to the mask frame. The state can be kept good. Other functions and effects are the same as those of the first embodiment.

Although the embodiments of the present invention have been described above, the present invention is not limited to the configurations and conditions described in the above embodiments, and various modifications are possible.
For example, in each of the above embodiments, KOH is used as an etchant in the silicon back surface etching step, but the present invention is not limited to KOH, and hydrofluoric nitric acid or the like may be used.

Further, in each of the above embodiments, the sulfuric acid and hydrogen peroxide is used as the cleaning liquid in the mask cleaning step. However, the cleaning liquid is not limited to the sulfuric acid and hydrogen peroxide, but may be ammonia peroxide and the like. is there.

In each of the above embodiments, a Ta film is used as the X-ray absorber film for simplicity of explanation. However, the present invention is not necessarily limited to the Ta film.
i-containing amorphous Ta film, Ge-containing amorphous Ta
A film or a W film may be used.

In each of the above embodiments, the SiC film is used as the membrane film.
The invention is not limited to the iC film, and a SiN film or a diamond film may be used.

In each of the above embodiments, a sheet-like adhesive is used as the adhesive. However, the adhesive is not necessarily required to be a sheet-like adhesive. May be selectively provided in the groove for use.

In the first and second embodiments, the epoxy resin is used as the adhesive.
The present invention is not limited to the epoxy resin. For example, another thermosetting resin such as a melanin resin may be used, and the curing temperature may be any temperature at which the O-ring or the elastic sheet can withstand.

Further, in the third embodiment, the elastic packing material for preventing the chemical solution from entering is used as the elastic packing material.
Although a ring is used, an elastic sheet may be used as in the second embodiment.

[0050]

According to the present invention, in the manufacturing process of the back side etching precedent type, when the mask frame for X-ray exposure and the mask frame are bonded using the epoxy resin or the ultraviolet curable resin, the adhesive is sandwiched. As described above, since two O-rings or elastic sheets are provided, the adhesive is not exposed to the etching liquid or the cleaning liquid in the silicon back surface etching step and the mask cleaning step, whereby the adhesive force of the adhesive is reduced. Since the X-ray exposure mask wafer does not decrease, the adhesion state between the X-ray exposure mask wafer and the mask frame can be maintained in a good condition, which greatly contributes to the improvement of the reliability of the X-ray exposure mask or cost reduction.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a basic configuration of the present invention.

FIG. 2 is an explanatory diagram of a manufacturing process partway through the first embodiment of the present invention.

FIG. 3 is an explanatory view of a manufacturing process of the first embodiment of the present invention after FIG. 2;

FIG. 4 is an explanatory diagram of a manufacturing process according to a second embodiment of the present invention.

FIG. 5 is an explanatory diagram of a manufacturing process according to a third embodiment of the present invention.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 X-ray exposure mask wafer 2 Mask frame 3 Elastic packing material groove 4 Elastic packing material groove 5 Elastic packing material 6 Elastic packing material 7 Adhesive 11 Silicon wafer 12 SiC film 13 SiC film 14 Opening 15 Ta film 16 Mask Frame 17 O-ring groove 18 O-ring groove 19 Adhesive groove 20 O-ring 21 O-ring 22 Adhesive sheet 23 Membrane area 24 X-ray absorber pattern 25 Elastic sheet groove 26 Elastic sheet groove 27 Elastic sheet 28 Elastic sheet 29 UV curable resin adhesive sheet

Claims (3)

[Claims] 1. A groove for an elastic packing material is provided at least on the surface of the mask frame and at least inside the surface on the side of the bonding surface with the mask wafer for X-ray exposure, and the elastic packing material is accommodated in the groove for the elastic packing material. An X-ray exposure mask, wherein an adhesive is provided outside the inner elastic packing material groove. 2. The X-ray according to claim 1, wherein said elastic packing material is made of one of an O-ring and an elastic sheet, and has chemical resistance and heat resistance to withstand a temperature of 250 ° C. Exposure mask. 3. The X-ray exposure mask according to claim 1, wherein the adhesive comprises one of an epoxy resin adhesive sheet and an ultraviolet curable resin adhesive sheet.