JP4228441B2 - Method for manufacturing transfer mask - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a transfer mask such as an electron beam exposure mask, a SCALPEL, an X-ray mask, and an ion beam transfer mask.
[0002]
[Prior art]
Recently, electron beam lithography, X-ray lithography, ion beam lithography, and the like have attracted attention as manufacturing technologies for next-generation ultrafine pattern elements and the like. A transfer mask is used for these exposures, and a transfer mask using a single crystal silicon wafer is used for ease of fine processing.
Here, FIG. 2A to FIG. 2H are sectional views showing a general manufacturing process of a conventional transfer mask in the order of steps.
[0003]
First, a bonded single crystal silicon substrate 14 including a single crystal silicon wafer 11, a silicon oxide film 12, and a single crystal silicon wafer 13 having a plane orientation of (100) is prepared (see FIG. 2A).
[0004]
Next, a resist pattern 15 is formed on the surface of the single crystal silicon wafer 13 by a normal lithography process (see FIG. 2B).
[0005]
Next, using the resist pattern 15 as a mask, the single crystal silicon wafer 13 of the bonded single crystal silicon substrate 14 is etched to a depth reaching the silicon oxide film 12 by dry etching to form an electron beam transmission mask pattern 16. (See FIG. 2 (c)).
[0006]
Next, a silicon nitride film 17 is formed on both surfaces of the bonded single crystal silicon substrate 14 by CVD (see FIG. 2D).
[0007]
Next, the silicon nitride film 17 formed on the single crystal silicon wafer 11 surface of the bonded single crystal silicon substrate 14 is patterned to form a support frame forming mask pattern 17a (see FIG. 3E).
[0008]
Next, in order to protect the surface of the single crystal silicon wafer 13 on which the electron beam transmission mask pattern 16 is formed, the bonded single crystal silicon substrate 14 is set on a jig, and a KOH aqueous solution or the like heated at 70 ° C. to 100 ° C. is used. The single crystal silicon wafer 11 is put into an etching solution, and the single crystal silicon wafer 11 is anisotropically etched along the plane direction to the silicon oxide film 12 serving as an etching stopper layer, using the support frame forming mask pattern 17a as a mask, and an electron beam transmission opening 18 and the support frame 11a are formed (see FIG. 2 (f)).
[0009]
Next, the silicon nitride film 17 and the support frame forming mask pattern 17a are removed by etching with hot phosphoric acid at 170.degree.
[0010]
Next, the silicon oxide film 12 under the electron beam transmission mask pattern 16 is removed by etching with hydrofluoric acid to form an electron beam transmission hole 16a (see FIG. 2G).
[0011]
Finally, a conductive film 19 such as heavy metal is formed on both surfaces to obtain a transfer mask (see FIG. 2H).
[0012]
However, the conventional manufacturing method has the following problems. When the single crystal silicon wafer 11 of the bonded single crystal silicon substrate 14 is etched to form the electron beam transmission opening 18 and the support frame 11a, if only wet etching is performed, the vicinity of the silicon oxide film 12 may occur. The silicon oxide film and the substrate itself are destroyed by the fluctuation pressure of the crystal and the distortion of the single crystal silicon substrate, and the yield is deteriorated.
[0013]
[Problems to be solved by the invention]
The present invention has been made in view of the above problems, and an object of the present invention is to provide a method for producing a high-quality transfer mask having a high manufacturing yield by preventing breakage of the transfer mask when the support frame is formed.
[0014]
In order to solve the above problems, the present invention provides a bonded single crystal silicon substrate in which a first silicon wafer, a silicon oxide film, and a second silicon wafer are laminated in this order; Forming an electron beam transmission opening and a support frame on the first silicon wafer of the bonded single crystal silicon substrate; and forming an electron beam transmission pattern on the second silicon wafer of the bonded single crystal silicon substrate. A step of forming an electron beam transmission hole corresponding to the electron beam transmission pattern in a silicon oxide film of the bonded single crystal silicon substrate, and forming the electron beam transmission opening and the support frame. After performing wet etching on one silicon wafer halfway, dry etching is performed until the first silicon wafer reaches the silicon oxide film. It is obtained by a method for producing a transfer mask which is characterized in that the quenching.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
As shown in FIGS. 1A to 1G, a method for manufacturing a transfer mask according to the present invention includes a single crystal silicon substrate 4 made of a single crystal silicon wafer 1, a silicon oxide film 2, and a single crystal silicon wafer 3. When the crystalline silicon wafer 1 is etched to form the electron beam transmission opening 7 and the support frame 1a, first, anisotropic etching is performed until the remaining thickness of the single crystal silicon wafer 1 becomes 5 to 100 μm by wet etching. The remaining amount of the single crystal silicon wafer 1 is processed by dry etching to form the electron beam transmission opening 7 and the support frame 1a.
By adopting such a processing method, a high-quality transfer mask with a high production yield can be produced.
[0017]
【Example】
The present invention will be described in detail with reference to the following examples.
1A to 1G are schematic cross-sectional views of a method for manufacturing a transfer mask according to the present invention.
[0018]
First, a bonded single crystal silicon substrate 4 in which a 500 μm-thick single crystal silicon wafer 1 having a plane orientation of (100) and a 20 μm-thick single crystal silicon wafer 3 were bonded together with a 1 μm-thick silicon oxide film 2 was produced ( FIG. 1 (a)).
[0019]
Next, an electron beam resist EBR900 (manufactured by Toray Industries, Inc.) was applied to the single crystal silicon wafer 3 surface of the bonded single crystal silicon substrate 4 to form an electron beam photosensitive layer having a thickness of 0.5 μm. Further, a pattern was drawn with an electron beam drawing machine with an acceleration voltage of 20 KV at a dose of 14 μC / cm ² , and development was performed using a dedicated developer to produce a resist pattern 5 (see FIG. 1B). In this embodiment, electron beam drawing using an electron beam resist is used, but stepper exposure using a normal photoresist may be used.
[0020]
Next, using the resist pattern 5 as a mask, the ICP dry etching apparatus is used to dry-etch the single crystal silicon wafer 3 to a depth reaching the silicon oxide film 2 using a fluorine-based gas such as SF _6. A beam transmission mask pattern 6 was formed. In this embodiment, the ICP dry etching apparatus is used as the dry etching. However, the present invention is not limited to this, and a dry etching apparatus using a discharge method such as RIE, magnetron RIE, ECR, microwave, helicon wave or the like may be used. Further, when the selection ratio with the resist pattern cannot be obtained, a silicon oxide film may be used instead of the resist.
[0021]
Next, after the resist pattern 5 is peeled off, a silicon nitride film 7 is formed to a thickness of 0.5 μm on both surfaces of the bonded single crystal silicon substrate 4 using a gas such as dichlorosilane and ammonia using low pressure CVD ( (Refer FIG.1 (d)).
[0022]
Next, the silicon nitride film 7 formed on the surface of the single crystal silicon wafer 1 is patterned by dry etching using a fluorine-based gas such as CHF ₃ to form a support frame forming mask pattern 7a (FIG. 1E). reference).
[0023]
Next, in order to protect the surface of the single crystal silicon wafer 3 on which the electron beam transmission mask pattern 6 is formed, the bonded single crystal silicon substrate 4 is set on a jig and heated to 30 to 100 ° C. The single crystal silicon wafer 1 was wet etched using the support frame forming mask pattern 7a as a mask, and was lifted from the etching solution before reaching the silicon oxide film to finish the wet etching. At this time, the remaining etching thickness of the single crystal silicon wafer 1 was set to 5 to 100 μm. Further, using an ICP dry etching apparatus, the remaining portion of the single crystal silicon wafer 1 is processed by dry etching using a fluorine-based gas such as SF ₆ until it reaches the silicon oxide film, and the electron beam transmission opening 8 and the support frame are processed. 1a was formed (see FIG. 1 (f)). In this embodiment, ICP is used for dry etching. However, the present invention is not limited to this, and a dry etching apparatus using a discharge method such as RIE, magnetron RIE, ECR, microwave, helicon wave, or the like may be used.
[0024]
Next, the silicon nitride film 7 and the support frame forming mask pattern 7a are removed by etching with hot phosphoric acid at 170 ° C., and the silicon oxide film 2 under the electron beam transmission mask pattern 6 is removed by etching with buffered hydrofluoric acid. Thus, an electron beam transmission hole 6a was formed (see FIG. 1G).
[0025]
Finally, a conductive mask 10 made of gold, platinum, or the like was formed on both surfaces by using a sputtering apparatus to form 0.05 to 0.2 μm to obtain a transfer mask (see FIG. 1G).
[0026]
【The invention's effect】
If the manufacturing method of the present invention is used, the silicon single crystal substrate is not broken when the support frame and the electron beam transmission opening are formed, the transfer mask manufacturing yield is improved, and a high-quality transfer mask can be obtained.
[Brief description of the drawings]
FIGS. 1A to 1G are schematic cross-sectional views showing manufacturing steps for manufacturing a transfer mask using the manufacturing method of the present invention.
FIGS. 2A to 2H are schematic cross-sectional views illustrating a conventional transfer mask manufacturing process in order of steps.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Single crystal silicon wafer 1a ... Support frame 2 ... Silicon oxide film 3 ... Single crystal silicon wafer 4 ... Bonding single crystal silicon substrate 5 ... Resist pattern 6 ... Electron beam transmission mask pattern 6a ... Electron beam transmission hole 7... Silicon nitride film 7 a... Support frame forming mask pattern 8. Electron beam transmission opening 9... Conductive film 11... Single crystal silicon wafer 11 a. 13 ... Single crystal silicon wafer 14 ... Bonded single crystal silicon substrate 15 ... Resist pattern 16 ... Electron beam transmission mask pattern 16a ... Electron beam transmission hole 17 ... Silicon nitride film 17a ... Mask for supporting frame formation Pattern 18 ... Electron beam transmission opening 19 ... Conductive film

Claims (1)

  Preparing a bonded single crystal silicon substrate in which a first silicon wafer, a silicon oxide film, and a second silicon wafer are laminated in this order;
Forming an electron beam transmission opening and a support frame on the first silicon wafer of the bonded single crystal silicon substrate;
Forming an electron beam transmission pattern on the second silicon wafer of the bonded single crystal silicon substrate;
Forming an electron beam transmission hole corresponding to the electron beam transmission pattern in a silicon oxide film of the bonded single crystal silicon substrate,
In the step of forming the electron beam transmission opening and the support frame, after the wet etching is performed on the first silicon wafer halfway, the dry etching is performed on the first silicon wafer until the silicon oxide film is reached.
A method of manufacturing a transfer mask characterized by the above.

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