JP6119144B2 - Stencil mask blank, stencil mask, and stencil mask manufacturing method - Google Patents

Description

  The present invention relates to a stencil mask blank, a stencil mask, and a stencil mask manufacturing method used for transferring an ultrafine circuit pattern performed using, for example, an electron beam or an ion beam.

  Lithography technology using light is used for nano-level microfabrication such as LSI circuit patterns. In recent years, with higher integration, a technique for producing a finer pattern is required, and the wavelength of an exposure light source is being shortened. For example, the exposure light source is shifted to KrF excimer laser (wavelength 248 nm) and ArF excimer laser (wavelength 193 nm), and further development of EUV lithography technology that uses short-wave soft X-rays (wavelength 13.5 nm) as the exposure light source Has been done. However, many problems such as light sources and resists remain as techniques for mass production.

  As described above, in the conventional photolithography technique, there is a concern about the resolution limit of light. As an alternative method, lithography using an electron beam or an ion beam has been proposed. .

  As a mask used in a lithography apparatus using an electron beam or an ion beam, a substrate having a three-layer structure (thin film silicon layer, silicon oxide layer, silicon layer) represented by an SOI substrate is used. Has proposed a stencil mask in which a penetrating pattern corresponding to a pattern to be transferred is formed. (For example, refer to Patent Document 1). By using the stencil mask and transferring the pattern using an electron beam or the like, it is expected that a pattern with a resolution much higher than that of lithography using conventional light can be produced.

  Various patterns are formed on the stencil mask depending on the application. However, if foreign matter exists in the pattern part of the stencil mask, the electron beam that passes through the foreign matter is blocked, so that the exact pattern cannot be transferred. It becomes a problem. Although foreign matter is a problem with a photomask, in the case of a photomask, the effect of the foreign matter on the transfer can be prevented by providing a dust-proof film called a pellicle on the pattern forming surface to protect the pattern. However, in the case of a stencil mask, since there is no material that can transmit an electron beam, there is no pellicle, and foreign matter in the pattern portion becomes a fatal problem.

  As a method for preventing foreign matter from adhering to the stencil mask, Patent Document 2 proposes a stencil mask structure in which the opening pattern portion is covered with a conductive metal film such as platinum. Foreign substances that can be prevented by this method are limited to foreign substances that are attracted by electrostatic attraction and adhere to them. Adhere to. Therefore, it is not possible to completely prevent the foreign matter from adhering only by covering with the conductive metal film. When the foreign matter is attached, it is necessary to remove the foreign matter by a cleaning process using a chemical solution.

  In precision cleaning of a general stencil mask or the like, ammonia perwater (a mixture of ammonia water and hydrogen peroxide solution) is used to remove foreign substances. The functions required for cleaning chemicals include “a function for separating foreign substances from the substrate” and “a function for preventing reattachment of foreign substances”. When the substrate is silicon, the surface is wet-etched by ammonia overwater, so that the foreign matter is separated from the substrate. In addition, since the zeta potentials of many substances such as silicon and silica have the same sign in a liquid having a high pH, foreign matter once separated does not adhere again. (The zeta potential is defined as the potential of the “slip surface” in the electric double layer formed around the fine particles in the liquid where liquid flow begins to occur.)

  On the other hand, when the cleaning process using ammonia excess water is performed, the pattern is also wet-etched, which increases the pattern size. When a silicon stencil mask is cleaned under cleaning conditions that can sufficiently remove foreign matter, the thickness increases by about 10 to 30 nm per time. If the pattern is several tens of μm or more, an increase in dimension due to cleaning is not a significant problem. However, if the pattern is a micro pattern of several μm or less, the yield is affected by an increase of about 10 to 30 nm, which is a serious problem.

JP-A-10-135103 JP 2004-146721 A

  Therefore, in order to create a stencil mask with no alien substance and excellent dimensional accuracy of the penetration pattern, the present invention has a structure that can remove the alien substance by washing with ammonia-hydrogen peroxide and prevent the penetration pattern from increasing in size due to washing. An object of the present invention is to provide a stencil mask blank having the stencil mask, a stencil mask manufactured using the blank, and a manufacturing method thereof.

The invention according to claim 1 of the present invention, a through-patterned layer through pattern by etching is formed, an intermediate layer functioning as one of formed on a surface etching stopper of said through-patterned layer, said through patterning A support layer that is formed on the surface of the intermediate layer opposite to the layer and maintains the shape of the through pattern, and the through pattern forming layer is formed of silicon that is in contact with the intermediate layer and can be removed by ammonia-hydrogen peroxide. And a dimension control layer that is formed of either diamond or diamond-like carbon (DLC) on the surface of the first release layer opposite to the intermediate layer and is resistant to ammonia overwater. , having a said first release layer opposite the second release layer formed of possible silicon removal with ammonia peroxide mixture is formed on a surface of the dimension control layer It is a stencil mask blank according to claim.

The invention according to claim 2 of the present invention includes a step of removing the first release layer and the second release layer of the stencil mask blank according to claim 1 with ammonia overwater. It is a manufacturing method .

The invention according to claim 3 of the present invention relates to a step of forming a through pattern by dry etching in the through pattern forming layer of the stencil mask blank according to claim 1, and the stencil mask blank on which the through pattern is formed. And a step of cleaning using ammonia perwater.

  By using the stencil mask blank provided in the present invention, the foreign matter adhering to the through pattern forming layer can be easily removed by a cleaning process using ammonia overwater, and the through pattern forming layer itself is dimensioned by ammonia overwater. Since it is not affected by changes, it is possible to provide a stencil mask with no foreign matter and excellent dimensional accuracy, leading to an improvement in yield.

It is sectional process drawing which shows an example of the stencil mask manufacturing method which concerns on embodiment of this invention. It is sectional process drawing which shows the other example of the stencil mask manufacturing method which concerns on embodiment of this invention.

  Hereinafter, an example of an embodiment of the stencil mask blank of the present invention will be described with reference to FIG.

The stencil mask blank 200 includes a penetrating pattern forming layer 100, an intermediate layer 130, and a support layer 140.
In other words, the stencil mask blank 200 is formed on the surface of the penetrating pattern forming layer 100, the intermediate layer 130 formed on one surface of the penetrating pattern layer 100, and the intermediate layer 130 opposite to the penetrating pattern forming layer 100. Support layer 140.
The penetration pattern forming layer 100 has a three-layer structure of a dimension control layer 120 provided with a peeling layer 111 and a peeling layer 112 on the upper and lower sides.
In other words, the penetrating pattern formation layer 100 includes the first release layer 112 that contacts the intermediate layer 130, the dimension control layer 120 formed on the surface of the first release layer 112 opposite to the intermediate layer 130, the first The first release layer 112 and the second release layer 111 formed on the surface of the dimension control layer 120 on the opposite side.

  Since the intermediate layer 130 is a material that serves as an etching stopper when forming a through pattern by etching, the intermediate layer 130 is determined by a material used for the through pattern forming layer 100 and the support layer 140 and a gas component used for etching. For example, if the penetration pattern forming layer 100 and the support layer 140 are etched with fluorine gas, the intermediate layer 130 is preferably silicon oxide, and the film thickness may be about 0.5 to 2 μm.

  The support layer 140 may be any material as long as it can form a desired through pattern using a general etching technique and has a strength sufficient to maintain the shape of the formed through pattern. An example is silicon.

  For the dimension control layer 120 constituting the penetrating pattern forming layer 100, a material that is resistant to ammonia water is used. Further, since it is a member that transmits an electron beam, it is preferably a conductive material that does not charge up, and can be processed by dry etching. Examples thereof include diamond and diamond-like carbon (DLC). It is done. The thickness is desirably about 1 μm to 60 μm. If it is less than 1 μm, breakage of the penetrating pattern is likely to occur, and if it exceeds 60 μm, the accuracy of the dimension and shape of the pattern is deteriorated.

  For the second release layer 111 and the first release layer 112 formed above and below the dimension control layer 120, a material that can be dissolved and removed by ammonia perwater used in the cleaning process is selected. Further, a material resistant to hydrofluoric acid used in the step of removing the intermediate layer 130 (implemented between (c) to (d) in FIG. 1) is desirable. When a material not resistant to hydrofluoric acid is selected, the first release layer 112 and the second release layer 111 are also removed at the same time in the step of removing the intermediate layer 130, and foreign substances adhering in the subsequent steps are removed. It becomes difficult. An example is silicon, and the thickness may be about 10 nm to 200 nm.

  As a process of forming the dimension control layer 120, the first release layer 112, and the second release layer 111, a known thin film forming method can be used as appropriate. For example, a sputtering method, a chemical vapor deposition method, a vacuum vapor deposition method, and the like can be given. Since the kinetic energy of the target atom is large, it is preferable to use a sputtering method that can produce a strong and difficult-to-peel film.

  Next, the stencil mask manufacturing method of the present invention will be described.

The stencil mask manufacturing method of the present invention includes at least a process of forming a through pattern in the stencil mask blank 200 by etching, and a process of cleaning using ammonia-hydrogen peroxide.
In other words, the stencil mask manufacturing method of the present invention includes a step of forming a through pattern by dry etching on the through pattern forming layer 100 of the stencil mask blank 200, and an ammonia overwater with respect to the stencil mask blank 200 on which the through pattern is formed. And a step of performing cleaning using

<The process of forming a penetration pattern in a stencil mask blank>
A known etching technique may be used as appropriate as the step of forming the through pattern on the stencil mask blank by etching. For example, by using the resist pattern as a mask, an optimal gas is selected according to the material to be etched, and the through pattern can be formed by dry etching. An example of a gas for etching silicon or diamond is a fluorine-based gas.

<Step of cleaning with ammonia overwater>
The cleaning using ammonia overwater, which is performed to remove foreign substances, is appropriately performed between the respective steps using a chemical solution obtained by mixing an appropriate amount of ammonia water and hydrogen peroxide water with ultrapure water. In some cases, megasonics can be used together. The concentration of ammonia and hydrogen peroxide is preferably about 0.1% to 5%, and the temperature of the chemical solution is preferably about 25 ° C to 80 ° C.

  An embodiment of the stencil mask manufacturing method of the present invention will be described with reference to FIGS. However, the present invention is not limited to the examples.

  First, the first release layer 112 and the second release layer 111 are made of silicon, the dimension forming layer 120 is made of diamond, the intermediate layer 130 is made of silicon oxide, and the support layer 140 is made of silicon. A stencil mask blank 200 was prepared (FIG. 1 (a)). The thicknesses of the second release layer 111 are 50 nm, the first release layer 112 is 30 nm, the dimension control layer 120 is 20 μm, the support layer is 500 μm, and the intermediate layer is 1 μm.

  Next, a resist was applied to the surface of the second release layer 111 of the stencil mask blank 200 with a spinner so as to have a film thickness of 1 μm, and after drawing with an electron beam, development processing was performed to form a desired resist pattern. Using the resist pattern as a mask and the intermediate layer 130 as an etching stopper, dry etching using a fluorocarbon mixed gas was performed, and the remaining resist pattern was removed with a solvent. Then, the foreign material adhering in the process was removed by washing with ammonia overwater for 10 minutes, thereby forming a pattern 310 on the pattern forming layer 100 (FIG. 1B). The conditions of ammonia overwater are an ammonia concentration of 1%, a hydrogen peroxide concentration of 1%, and a liquid temperature of 70 ° C.

  Next, a resist was applied to the support layer 140 side of the stencil mask blank 200 with a spinner so as to have a film thickness of 40 μm, and a desired pattern was exposed and developed to obtain a resist pattern. Using the resist pattern as a mask, the intermediate layer 130 was used as an etching stopper, dry etching with a fluorocarbon mixed gas was performed, and the remaining resist was removed with a solvent to form an opening 320 (FIG. 1C).

  Subsequently, the intermediate layer in the opening 320 was removed by 10% hydrofluoric acid treatment to form a through pattern 330 (FIG. 1 (d)). At this point, the first release layer 112 and the second release layer 111 remain because they are silicon resistant to hydrofluoric acid.

  Finally, the stencil mask 400 was obtained by removing the foreign matter adhering during the process by washing with ammonia water (FIG. 1 (e)). The conditions of ammonia overwater are an ammonia concentration of 1%, a hydrogen peroxide concentration of 1%, and a liquid temperature of 70 ° C. The washing time is 20 minutes. At this time, the first peeling layer 112 and the second peeling layer 111 are removed from the penetration pattern 330, and the dimension control layer 120 appears on the surface. Since the dimension control layer 120 is resistant to ammonia hydrogen peroxide, there is no increase in pattern dimension due to cleaning, and the dimensions are as designed.

  First, the first release layer 112 and the second release layer 111 are made of silicon, the dimension forming layer 120 is made of diamond, the intermediate layer 130 is made of silicon oxide, and the support layer 140 is made of silicon. A stencil mask blank 200 was prepared (FIG. 2 (a)). The thicknesses of the first release layer 112 and the second release layer 111 are 50 nm, the dimension control layer 120 is 20 μm, the support layer is 500 μm, and the intermediate layer is 1 μm.

  Next, a resist was applied to the support layer side of the stencil mask blank 200 with a spinner so as to have a film thickness of 40 μm, and a desired pattern was exposed and developed to obtain a resist pattern. Using the resist pattern as a mask and using the intermediate layer 130 as an etching stopper, dry etching was performed with a fluorocarbon-based mixed gas, and the remaining resist was removed with a solvent to form an opening 320 (FIG. 2B).

  Next, the intermediate layer in the opening 320 was removed with hydrofluoric acid, and the foreign matter adhering during the process was removed by washing with ammonia / hydrogen peroxide for 10 minutes, thereby forming the structure shown in FIG. The conditions of ammonia overwater are an ammonia concentration of 1%, a hydrogen peroxide concentration of 1%, and a liquid temperature of 70 ° C.

  Next, a resist was applied to the surface of the second release layer 111 of the stencil mask blank 200 with a spinner so as to have a film thickness of 1 μm, and after drawing with an electron beam, development processing was performed to form a desired resist pattern. Using the resist pattern as a mask, dry etching using a fluorocarbon-based mixed gas was performed, and the remaining resist pattern was removed with a solvent, thereby forming a through pattern 330 in the pattern formation layer 100 (FIG. 2D). .

  Finally, the stencil mask 400 was obtained by removing the foreign matter adhering during the process by washing with ammonia / hydrogen peroxide (FIG. 2 (e)). The conditions of ammonia overwater are an ammonia concentration of 1%, a hydrogen peroxide concentration of 1%, and a liquid temperature of 70 ° C. The washing time is 20 minutes. At this time, the penetration pattern 330 has the first release layer 112 and the second release layer 111 removed, and the dimension control layer 120 is the surface. Since the dimension control layer 120 is resistant to ammonia hydrogen peroxide, the penetrating pattern is finished with the dimensions as designed.

  By producing a stencil mask using the methods of Example 1 and Example 2, defects due to foreign matter were reduced, and the dimensional accuracy of the through pattern was improved, so that the product direct rate was greatly improved.

  The present invention can be suitably used as a method for manufacturing a stencil mask used in transferring an ultrafine circuit pattern performed using an electron beam or an ion beam.

100 ... Penetration pattern forming layer 111 ... Release layer (second release layer)
112 ... Release layer (first release layer)
120 ... Dimension control layer 130 ... Intermediate layer 140 ... Support layer 200 ... Stencil mask blank 310 ... Pattern 320 ... Opening 330 ... Penetration pattern 400 ... Stencil mask

Claims (3)

A penetration pattern forming layer in which a penetration pattern by etching is formed;
An intermediate layer formed on one surface of the penetrating pattern forming layer and functioning as an etching stopper;
A support layer that is formed on the surface of the intermediate layer opposite to the penetration pattern forming layer and maintains the shape of the penetration pattern;
The penetration pattern forming layer is
A first release layer formed of silicon that contacts the intermediate layer and can be removed with ammonia-hydrogen peroxide;
A dimension control layer that is formed of either diamond or diamond-like carbon (DLC) on the surface of the first release layer opposite to the intermediate layer, and is resistant to ammonia hydrogen peroxide;
A second release layer formed of silicon that is formed on the surface of the dimension control layer opposite to the first release layer and that can be removed with ammonia-hydrogen peroxide.
A stencil mask blank characterized by that. A method for producing a stencil mask , comprising the step of removing the first release layer and the second release layer of the stencil mask blank according to claim 1 with ammonia-hydrogen peroxide. Forming a penetrating pattern by dry etching on the penetrating pattern forming layer of the stencil mask blank according to claim 1;
Cleaning the ammonia stencil mask blank on which the penetrating pattern is formed using ammonia overwater; and
A method for producing a stencil mask, comprising:

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