JP2001185481A - Transfer mask - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing method that can easily and stably manufacture a low cost transfer mask with a high precession aperture pattern. SOLUTION: This transfer mask has a conductive layer 2 formed on a substrate surface, a supporting frame formed by processing the back side of the substrate, a thin film supported by the frame, and also a through hole formed within the thin film. The conductive layer 2 has metallic element density, the value of which is larger than 6 g/cc, an electric resistivity, the value of which is smaller than 60 μΩ.cm (at 25 deg.C), and also thermal conductivity, the value of which is larger than 0.04 cal/cm/cm2/sec/ deg.C. The layer is not magnetic and it is constituted of a material that is conductive and is liable to a dry etching.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a transfer mask and a method for manufacturing the same.

[0002]

2. Description of the Related Art At present, electron beam lithography, ion beam lithography, X-ray lithography and the like have been attracting attention as a manufacturing technology for next-generation sub-half micron or quarter micron ultra-miniaturized devices. Whether it will become mainstream is still unclear.

[0003] Under such circumstances, Si, Mo, A are used as masks for electron beam exposure, ion beam exposure, and X-ray exposure.
A transfer mask (stencil mask; St. mask) in which a pattern to be exposed is formed by making a hole (opening) in a metal foil such as Au.
Encil masks) have been developed and are being put into practical use, but have not yet been put into practical use for mass production.

[0004] In particular, in electron beam lithography in which a pattern is drawn using an electron beam, portions corresponding to portions obtained by dividing a pattern to be exposed, which are called collective exposure, block exposure or cell projection exposure, are used. Using a mask in which various types of transmission figures (openings) are formed, an electron beam is formed through these openings, and a predetermined section (block or cell) is partially exposed collectively, and this operation is repeated to draw. Has been proposed.
The drawing method using the partial batch exposure is a problem in the direct drawing method (so-called single-stroke writing method) in which the exposure pattern is scanned by an electron beam (thin beam spot) which is already in practical use (so-called single-stroke writing method). This is a method devised to cope with a long and low throughput, and enables higher-speed drawing than a direct drawing method using a variable rectangle.

Various methods of manufacturing a transfer mask used for such partial batch exposure and the like have been conventionally studied. For example, a method of forming a silicon thin film portion using an SOI (Silicon on Insulator) substrate having a structure in which _two silicon plates are bonded via an SiO ₂ layer and using the SiO ₂ layer as an etching stop layer (etching stopper layer) ( JP-A-6-130655), a method of forming an opening (opening) pattern portion using a silicon substrate by electric discharge machining (JP-A-5-217876), or coating a silicon substrate with a photosensitive glass. A method of using the photosensitive glass as it is as a mask material and omitting a resist process (Japanese Patent Laid-Open No. 4-240719) has been proposed.

Among these various manufacturing methods, in consideration of the durability of the thin film portion during the production of the transfer mask and the processing accuracy of the opening, the SOI substrate is used as the substrate, and the opening pattern portion is processed with high precision by dry etching. And
Generally, a method of processing the back surface portion of the substrate corresponding to the opening by wet etching (wet etching). More specifically, for example, Si / SiO ₂ / Si
After a dry etching (trench etching) mask layer made of SiO _{2 is} formed on the opening pattern forming surface side of the SOI substrate using an SOI substrate having a multilayer structure of
The entire substrate is covered with a silicon nitride layer, an opening is formed on the back surface of the silicon nitride layer, the back surface of the substrate is processed by wet etching to form a thin film portion, the silicon nitride layer is removed, and then the dry etching on the opening pattern side is performed. A method for performing processing has been proposed.

On the contrary, there has been proposed a method in which the processing order is changed and the opening pattern is processed first, and then the back surface of the substrate is processed. Further, a method using a boron layer as an etching stopper layer has been proposed (Japanese Patent Application Laid-Open No. 2-76216).

In a conventional transfer mask manufactured as described above, a silicon thin film portion having an opening as it is has poor durability against electron beams and poor heat radiation characteristics. A metal conductive layer is formed on the mask to improve the heat radiation characteristics and durability of the mask during electron beam irradiation.

[0009]

However, in the above-described conventional method for manufacturing a transfer mask, generally, after an opening is formed, a metal conductive layer is formed by a vacuum thin film forming method such as a sputtering method, a vapor deposition method, or a CVD method. Therefore, there is the following problem. In other words, in the method in which the metal conductive layer is formed by the sputtering method after the opening is formed, the shape of the metal conductive layer at the edge of the opening is lower because the mean free path of molecules during film formation is short in the sputtering method. There is a problem that the silicon thin film is overhanged and the aperture accuracy is impaired. In the method of forming a metal conductive layer by a vapor deposition method or a CVD method after forming an opening, it is difficult to control the film stress of the formed metal conductive layer. Generally, a film forming temperature of 250 ° C. or higher is required, and there is a problem that the silicon thin film portion as a base is distorted or damaged due to the influence of the film forming temperature. Furthermore, in the vapor deposition method and the CVD method, the average free path of the molecules during the film formation is relatively long and the step coverage is good, so that a film having an uneven thickness is deposited also on the side wall of the opening, or 5 × 10 ^-5 to
Under the condition of about rr or less, the opening edge portion is in an overhang state, and there is a problem that the opening accuracy is impaired.

Several countermeasures have been proposed for such a problem. For example, after forming an inorganic layer pattern on a silicon substrate, using this inorganic layer pattern as a mask, metal tungsten (metal conductive layer) is selectively deposited on the silicon substrate, the inorganic layer is removed, and the silicon substrate is placed on the back side. A method of manufacturing a transfer mask using metal tungsten as a mask material as it is by dissolving and removing the same from metal has been proposed (JP-A-6-97025). However, with this method, it is difficult to selectively deposit metal tungsten in the first place, and even if it can be formed, the accuracy of the opening pattern cannot be reduced, which is not practical.

As another method, a large amount of boron is implanted into the surface of a silicon substrate to form a boron implanted layer, a tungsten layer (metal conductive layer) is formed on the boron implanted layer, and formed on the tungsten layer. A method is proposed in which a trench is formed on the boron-implanted layer and the tungsten layer by dry etching using a resist pattern as a mask, and then the silicon substrate is dissolved and removed from the back side by wet etching using an alkaline solution to produce a transfer mask. (JP-A-4-188645). However, in this method, when the silicon substrate is wet-etched with an alkaline solution, the boron-implanted layer having a high concentration in the alkaline solution is not dissolved or hardly dissolved. As described above, the boron-implanted layer having a high dose that is not or hardly dissolved in an alkaline solution has a very low etching rate in dry etching or is difficult to etch. Therefore, this method cannot avoid a decrease in throughput and is not practical. Further, since a high-cost process such as an ion implantation process is required, an increase in manufacturing cost cannot be avoided.

The present invention has been made in view of the above-described problems, and has as its object to provide a method of manufacturing a transfer mask capable of easily and stably manufacturing a transfer mask having a highly accurate opening pattern at low cost. .

[0013]

In order to achieve the above object, in a method of manufacturing a transfer mask according to the present invention, a back surface of a substrate is etched to form a support frame portion and a thin film portion supported by the support frame portion. In the method for manufacturing a transfer mask including a step and a step of forming a through hole in the thin film portion, at least,
Forming a conductive layer on the substrate surface, and on the conductive layer,
A step of forming an etching mask layer of the conductive layer, a step of patterning the etching mask layer formed on the conductive layer into a desired shape using lithography technology, and using the patterned etching mask layer as a mask Continuously processing the conductive layer and the substrate surface to a predetermined depth by dry etching technology.

Further, the method for producing a transfer mask according to the present invention comprises:
In the method of manufacturing a transfer mask, preferably, the conductive layer is formed of any one of tungsten, tantalum, molybdenum, and iridium, or an alloy containing these metals, or an intermetallic compound of these metals. The etching mask layer of the conductive layer is made of SiO ₂
In the above-described method for producing a transfer mask, a wet etching mask layer is further formed on the back surface of the substrate, and the wet etching mask layer is formed on the back surface of the substrate. Patterning by lithography technology, forming a low-temperature curing resin layer on the surface and side surfaces of the substrate,
A step of performing a hardening treatment, and a step of immersing the back surface of the substrate on which the low-temperature curing resin layer is formed in an etchant and performing a wet etching process on the back surface of the substrate. A configuration that is a resin that cures, a configuration in which the low-temperature curing resin is a resin including at least one or more of a fluorine-based resin, an ethylene-based resin, a propylene-based resin, a silicon-based resin, a butadiene-based resin, and a styrene-based resin. Alternatively, the wet etching mask layer is formed of any one of tungsten, zirconium, titanium, chromium, nickel, and silicon, or an alloy containing these metals, or a mixture of these metals or alloys with oxygen, nitrogen, or carbon. And a metal compound containing at least one of the above elements.

Hereinafter, the present invention will be described in detail. In the method for manufacturing a transfer mask of the present invention, a plurality of steps are included, and the order of these steps can be arbitrarily determined according to the purpose. However, for convenience of explanation, description will be made in accordance with one of the steps.

FIG. 1 is a process explanatory view showing an example of a process for manufacturing a transfer mask according to the present invention. In the present invention, as shown in FIG. 1, first, a conductive layer 2 is formed on the surface of a substrate 1 (FIG. 1A). Here, as the substrate material, Si, M
o, Al, Au, Cu, etc., but chemical resistance,
From the viewpoint of processing conditions, dimensional accuracy, etc., silicon substrates, SO
It is preferable to use an I substrate or the like.

The conductive layer 2 has an actual density of the metal element of more than 6 g / cc and an electric resistivity of 60 μΩ · cm.
(At 25 ° C.) and thermal conductivity of 0.04 cal
/ Cm / cm ² / sec / ° C., preferably satisfying all of these conditions, and is made of a conductive material which is not magnetic and can be dry-etched. Specifically, the conductive layer 2 is preferably made of a metal material such as a metal such as tungsten, tantalum, molybdenum, and iridium, an alloy containing these metals, or an intermetallic compound of these metals. this is,
These metals and the like can be dry-etched, and the value of the linear expansion coefficient of these metals and the like is closer to the value of the linear expansion coefficient of silicon as a transfer mask material, compared to the gold-based elements. This is because pattern displacement due to thermal distortion or the like during electron beam irradiation can be significantly reduced.

Examples of the method for forming the conductive layer 2 include a thin film forming method such as a sputtering method, a vapor deposition method, a CVD method, and an electrodeposition method, and a high-quality film level (density of the film, crystal structure, defect-free method). Therefore, it is preferable to use a sputtering method or a CVD method.

It is appropriate that the thickness of the conductive layer 2 be in the range of 0.1 to 3.0 μm. The thickness of the conductive layer 2 is 0.1 μ
If it is thinner, the durability to electron beams becomes poor, and it becomes 3.0.
If it exceeds μ, high-precision dry etching becomes difficult.

Next, an SiO ₂ layer (an etching mask layer of a conductive layer) 3 and an SiO ₂ layer 4 are formed on the conductive layer 2 and on the back surface of the substrate 1, respectively (FIG. 1B). here,
The SiO ₂ layer 3 may be formed only on the conductive layer 2. However, considering the warpage of the substrate 1, it may be formed on both surfaces of the substrate with a well-balanced thickness (for example, 0.5 to 3.0 μ). preferable. Examples of the method for forming the SiO ₂ layer include a thin film forming method such as a sputtering method, a vapor deposition method, a thermal oxidation method, and a CVD method.In order to avoid deterioration of the conductive layer due to heating such as prevention of surface oxidation of the conductive layer, It is preferable to use a thin film forming method such as a room temperature sputtering method and a room temperature CVD method. Note that SiO
Instead of the _two layers 3, a layer such as a Si 3 N 4 layer, a SiC layer, a sialon (composite mixture of Si and Al) layer, or a SiON layer may be formed as an etching mask layer for the conductive layer 2.

Next, the SiO ₂ layer 3 is patterned into a desired shape by using a lithography technique. Specifically, for example, a resist is applied on the SiO ₂ layer 3, a resist pattern (not shown) is formed by exposure and development, and the resist pattern is used as a mask to form the SiO ₂ layer 3.
Is etched to form a resist pattern on the SiO ₂ layer 3.
(FIG. 1B). In this case, in consideration of the pattern accuracy, the etching of the SiO ₂ layer 3 is preferably performed by dry etching using a fluorocarbon-based gas as an etching gas.

Next, after removing the resist, perform trench etching of the conductive layer 2 and the substrate 1 surface by dry etching (etching processing into a groove shape) the SiO ₂ layer 3 that is patterned as a mask, SiO ₂
The pattern is transferred to these (FIG. 1 (c)).

In this case, the depth of the trench etching on the surface of the substrate 1 is set to a predetermined depth (for example, 5 to 30 μm) so as to form a thin film portion having a predetermined thickness.

The etching gas used for the dry etching is not particularly limited. For example, as the etching gas for tungsten, CBrF ₃ gas, CF ₄ / O ₂
A mixed gas or the like is used as a tantalum etching gas
₄ gas or the like is used as an etching gas for the silicon substrate.
Examples thereof include Br gas, Cl ₂ / O ₂ mixed gas, and SiCl ₄ / N ₂ mixed gas. Note that the conductive layer and the silicon substrate may be continuously etched with the same etching gas using SF ₆ gas or the like. As described above, when etching is performed continuously with the same etching gas, there is no difference in anisotropy and isotropic etching, and this is advantageous in that high throughput can be obtained.

According to the present invention, the opening including the conductive layer can be formed in a single step and in a short time by continuous dry etching, as compared with the related art. That is, the process can be simplified as compared with the conventional method of forming a metal conductive layer after forming an opening, and the opening including the conductive layer can be completed in a shorter time than a technique using a boron injection layer. A portion can be formed. Further, according to the present invention, the opening including the conductive layer can be formed with high precision and easily as compared with the related art. In other words, compared to the conventional method of forming a metal conductive layer after forming an opening, the accuracy of the opening including the conductive layer can be improved, and it is easier than a technique using a boron injection layer. An opening including a conductive layer can be formed.

Next, the unnecessary SiO ₂ layers 3, 4
Is removed with a stripper (buffered hydrofluoric acid, dilute hydrofluoric acid, etc.), and a wet etching mask layer 5 is formed on the back surface of the substrate (FIG. 1).
(D)), this wet etching mask layer 5 is patterned by a lithography technique (FIG. 1).
(E)). However, since the SiO ₂ layer 4 can be used as it is as the wet etching mask layer 5 depending on the type of the wet etching solution,
_It may be used as it is without removing the _two layers.

Here, the wet etching mask layer 5
Is a metal simple substance such as tungsten, zirconium, titanium, chromium, nickel, silicon, or an alloy containing these metals, or these metals or alloys and oxygen,
It is preferable to use a metal compound containing at least one element of nitrogen and carbon. This is because these metal systems can be patterned by low-temperature wet etching, and the removal of these metal systems is also performed at 100 ° C.
This is because the following low-temperature wet etching can be performed, so that the thin film portion is not damaged during these processes.

The wet etching mask layer 5 can be formed by a thin film forming method such as a sputtering method, a vapor deposition method, or a CVD method. From the viewpoint that high-quality film quality is required to avoid this, and from the viewpoint of avoiding damage such as cracks due to thermal stress or the like in high-temperature film formation, sputtering at 350 ° C. or less is performed. Or CVD is preferred.

The thickness of the wet etching mask layer 5 is
Suitably, it is in the range of 1,000 to 10,000 Angstroms. If the thickness of the wet etching mask layer 5 is less than 1000 angstroms, the silicon substrate cannot be completely covered. If it exceeds 10,000 angstroms, it takes a long time to form the film and the influence of the film stress increases.

The patterning of the wet etching mask layer 5 is specifically performed as follows.
A resist is applied thereon, and a resist pattern (not shown) is formed by a lithography method. Using this resist pattern as a mask, the wet etching mask layer 5 is wet-etched with an etching solution to be patterned (FIG. 1 (e) )).

The etchant used for wet etching is not particularly limited. For example, a 4% dilute aqueous solution of hydrofluoric nitric acid or the like is used as an etchant for titanium, and ceric ammonium nitrate / perchloric acid is used as an etchant for chromium. Aqueous solutions and the like, ferric chloride and the like as nickel etching liquids, and red blood salt (potassium ferricyanide) aqueous solution and the like as tungsten etching liquids.

Next, a low-temperature curable resin layer 6 is formed on the surface and side surfaces of the substrate, and is cured by heating or leaving it at room temperature (FIG. 1 (e)). The low-temperature curable resin layer 6 plays a role as a protective layer for portions other than the back surface of the substrate when the back surface of the substrate is subjected to wet etching.

Here, it is preferable to use a resin that cures at a low temperature of 200 ° C. or less as the low-temperature curing resin. When the curing temperature exceeds 200 ° C., distortion and breakage of the thin film portion and the like occur due to the influence of thermal stress during the curing process. In order to more completely avoid the influence of such thermal stress, it is more preferable to use a resin that cures at room temperature.

Examples of such a low-temperature curing resin include resins containing at least one of a fluorine resin, an ethylene resin, a propylene resin, a silicon resin, a butadiene resin, and a styrene resin.

A low-temperature curing resin layer 6 is formed on the surface and side surfaces of the substrate.
Examples of a method for forming a film include a spin coating method, a dipping method, and a spraying method, and the spin coating method is preferable in consideration of handling, work efficiency, and the like. The coating on the side surface of the substrate is performed by causing the resin to flow around the side surface of the substrate during the initial low-speed rotation in the spin coating method or the like.

The thickness of the low-temperature curing resin layer 6 is 30 to 100.
A suitable value is 0 microns. If the thickness of the low-temperature curable resin layer 6 is less than 30 microns, the durability to the etchant and the function as a protective layer will be poor, and if it exceeds 1000 microns, the curing and removal processes will take time.

The low-temperature cured resin layer does not affect other parts due to thermal stress when forming and removing the layer.
It can be easily formed by a spin coating method or the like, has excellent step coverage, and can completely prevent liquid erosion of an etching solution. Therefore, it contributes to stably and easily manufacturing the transfer mask.

Next, the back surface of the substrate on which the low-temperature curable resin layer 6 is formed is immersed in an etching solution, and the back surface of the substrate is etched (FIG. 1F). Here, examples of the etchant include an alkaline aqueous solution such as KOH and NaOH, an alkaline aqueous solution containing alcohol and the like, an organic alkali, and the like.

The etching temperature is preferably set to a low temperature of 150 ° C. or less, more preferably 110 ° C. or less, in order to avoid the influence of thermal stress.
Examples of the etching method include a dipping (dipping) method.

In the present invention, since the etching amount (depth) on the back surface of the substrate can be controlled by controlling the etching time, an etching stopper layer (SiO ₂ , boron, etc.) on an SOI substrate or the like becomes unnecessary, and thus Silicon (ordinary silicon substrate) can be used, which can contribute to cost reduction.

Finally, the unnecessary low-temperature cured resin layer 6 is removed with an organic solvent or the like, and the wet etching mask layer 5 is similarly removed with an etching solution or the like to obtain a transfer mask (FIG. 1 (g)). )). At this time, the removal temperature of these layers is preferably set to a low temperature of 100 ° C. or less, more preferably room temperature, in order to avoid the influence of thermal stress.

Although the transfer mask manufacturing method of the present invention includes a plurality of steps as described above, the order of these steps is not limited, and the order of the steps can be arbitrarily determined according to the purpose. The feature is that it can be done, and the degree of freedom is high.

[0043]

EXAMPLES The present invention will be described below more specifically based on examples.

Embodiment 1 FIG. 2 is a process explanatory view showing an example of a process for manufacturing a transfer mask according to the present invention. As shown in FIG. 2, first, a tungsten layer 12 having a thickness of 1 μm is formed on a silicon substrate 11 by a sputtering method (FIG. 2A), and further, a sputtering method is formed on the tungsten layer 12 and on the back surface of the silicon substrate 11 respectively. Thus, 2 μm thick SiO ₂ layers 13 and 14 were formed.

[0045] Then, by lithography and a resist is applied on the SiO ₂ layer 13 to form a resist pattern (not shown), etching of the SiO ₂ layer 13 by dry etching using the resist pattern as a mask, the resist pattern This was transferred to the SiO ₂ layer 3 (FIG. 2B).

After removing the resist, the tungsten layer 12 and the surface of the silicon substrate 11 were trench-etched by dry etching using the patterned SiO ₂ layer 13 as a mask, and the SiO ₂ pattern was transferred to them (FIG. 2C). )). Note that the tungsten layer 12
CBrF ₃ was used as an etching gas, and HBr was used as an etching gas for the surface of the silicon substrate 11.

Next, after removing the SiO 2 layers 13 and 14 with buffered hydrofluoric acid, a thickness of 3
A 2,000 angstrom metal titanium layer 15 was formed (FIG. 2D).

A resist is applied on the metal titanium layer 15 and a resist pattern (not shown) is formed by a lithography method.
The metal titanium layer 15 was patterned by wet etching with a 5% aqueous solution of dilute hydrofluoric nitric acid (FIG. 2E).

Next, a fluororesin was applied to the surface and side surfaces of the substrate to form a fluororesin layer 16 and heated at 150 ° C. to cure the fluororesin layer 16 (FIG. 2).
(E)).

This substrate was immersed in a KOH aqueous solution heated to 100 ° C. to etch the back surface of the silicon substrate 11 (FIG. 2F).

Finally, the fluororesin layer 16 was removed with an organic solvent, and the metal titanium layer 15 was removed with a 4% dilute aqueous nitric acid solution to obtain a transfer mask (FIG. 2 (g)).

Embodiment 2 FIG. 3 is a process explanatory view showing an example of a process for manufacturing a transfer mask according to the present invention. As shown in FIG. 3, first, a 1 μm thick tantalum layer 32 is formed on an SOI substrate 31 by a sputtering method.
(FIG. 3A), and a chromium nitride layer 35 having a thickness of 3000 Å was formed on the back surface of the SOI substrate 31 by a room-temperature sputtering method (FIG. 3B).

A resist is applied on the chromium nitride layer 35, and a resist pattern (not shown) is formed by lithography. Using this resist pattern as a mask, the chromium nitride is treated with a ceric ammonium nitrate / perchloric acid aqueous solution. The layer 35 was wet-etched to pattern the chromium nitride layer 35 (FIG. 3B).

Next, an ethylene-propylene-based resin was applied to a thickness of 300 μm on the surface and side surfaces of the substrate to form an ethylene-propylene-based resin layer 36, which was cured by heating at 90 ° C. (FIG. 3). (C)).

The substrate was immersed in an aqueous KOH solution containing 10% of IPA (isopropyl alcohol) heated to 70 ° C.
The thin film portion was formed by etching the back surface of the SOI substrate 31 (FIG. 3D).

Next, the ethylene-propylene resin layer 3
6 was removed with an organic solvent, and the metal chromium layer 35 was removed with the same ceric ammonium nitrate / perchloric acid aqueous solution as described above (FIG. 3 (e)).

Next, a 1.8 μm thick SiO 2 layer 33 was formed on the tantalum layer 32 by the CVD method. Then, S
On iO ₂ layer 33 by a resist is applied lithography to form a resist pattern (not shown), etching of the SiO ₂ layer 33 by dry etching using the resist pattern as a mask, the resist pattern in the SiO ₂ layer 33 It was transferred (FIG. 3 (e)).

After removing the resist, trench etching is performed on the surface of the tantalum layer 32 and the SOI substrate 31 by dry etching using the patterned SiO ₂ layer 33 as a mask to form openings (transmission holes) (FIG. 3 ( f)). Incidentally, using Cl2 as etching gas for the tantalum layer 32 was used Cl ₂ / SF ₆ / SiCl ₄ mixed gas as the etching gas of the SOI substrate 31 surface.

Finally, the SiO ₂ layer 33 and the intermediate SiO ₂
The layer was removed with buffered hydrofluoric acid to obtain a transfer mask (FIG. 3).
(G)).

Embodiment 3 FIG. 4 is a process explanatory view showing an example of a process for manufacturing a transfer mask according to the present invention. As shown in FIG. 4, first, a tungsten layer 42 having a thickness of 1 μm is formed on an SOI substrate 41 by a sputtering method (FIG. 4A).
A nickel layer 45 having a thickness of 2000 angstroms was formed on the back surface by a room temperature sputtering method (FIG. 4B).

A resist is applied on the nickel layer 45, a resist pattern (not shown) is formed by lithography, and the nickel layer 45 is wet-etched with a ferric chloride solution using the resist pattern as a mask. The nickel layer 45 was patterned (FIG. 4)
(B)).

Next, a 2.0 μm thick photosensitive SOG (spin-on
On-glass) layer 43 is formed, and this photosensitive SOG layer 43 is formed.
Was patterned by electron beam lithography and then baked at 200 ° C. to obtain a patterned SiO ₂ layer 43 (FIG. 4C).

Subsequently, the surface of the tungsten layer 42 and the surface of the SOI substrate 41 are subjected to trench etching by dry etching using the patterned SiO ₂ layer 43 as a mask, and the SiO ₂ pattern is transferred to these (FIG. 4).
(D)). Note that the same Cl ₂ / SF ₆ mixed gas was used as the etching gas for the tungsten layer 42 and the etching gas for the silicon layer on the surface of the SOI substrate 41, and the etching was continuously performed.

Next, a silicon resin was applied to the surface and side surfaces of the substrate at a thickness of 200 μm to form a silicon resin layer 46, and the silicon resin layer 46 was cured by heating at 100 ° C. (FIG. 4). (E)).

This substrate is formed by using the silicon resin layer 46 as a protective layer and the nickel layer 45 as an etching mask layer.
Immersed in an aqueous solution of NaOH heated to
The back surface was etched to form a thin film portion (FIG. 4).
(F)).

Finally, the silicon resin layer 46 is removed with an organic solvent, and the nickel layer 45 is removed with a ferric chloride solution.
The iO ₂ layer 43 and the intermediate SiO ₂ layer were removed with buffered hydrofluoric acid to obtain a transfer mask (FIG. 4G).

In Examples 1 to 3, it was confirmed that the low-temperature curable resin layer could completely prevent the erosion of the etching solution during the wet etching of the back surface of the substrate. In addition, it was confirmed that the influence of thermal stress can be avoided in all the steps, and it was confirmed that the transfer mask could be stably manufactured without any breakage or the like during the steps.

Although the present invention has been described with reference to the preferred embodiments, the present invention is not necessarily limited to the above embodiments. For example, similar results were obtained even when zirconium, tungsten, or the like was employed as the wet etching mask layer. Similar results were obtained even when low-temperature curable resins such as butadiene-based resins, styrene-based resins, and mixed resins including those used in Examples were used.
Further, the method for producing a transfer mask of the present invention can be used for a method for producing an ion beam exposure mask and the like in addition to an electron beam exposure mask.

[0069]

As described above, according to the method for manufacturing a transfer mask of the present invention, the formation of the opening including the conductive layer can be performed.
Continuous dry etching can be performed in one step in a short time, and can be performed with high precision and ease.

Further, by employing a low-temperature curable resin layer and a wet etching mask layer which can be formed and removed at a low temperature, the influence of thermal stress can be avoided. Cost reduction can be achieved.

Further, the low-temperature curable resin layer can be easily formed, has excellent step coverage, and can completely prevent liquid erosion of the etching solution.

Further, according to the present invention, an etching stopper layer of the substrate is not required, and bare silicon can be used.

As described above, according to the present invention, a transfer mask having a highly accurate opening pattern can be easily and stably manufactured at low cost.

[Brief description of the drawings]

FIG. 1 is a process explanatory view showing an example of a process for manufacturing a transfer mask according to the present invention.

FIG. 2 is a process explanatory view showing another example of a process for manufacturing a transfer mask according to the present invention.

FIG. 3 is a process explanatory view showing another example of a process for manufacturing a transfer mask according to the present invention.

FIG. 4 is a process explanatory view showing another example of a process for manufacturing a transfer mask according to the present invention.

[Description of Signs] 1 Substrate 2 Conductive layer 3 SiO ₂ layer 4 SiO ₂ layer 5 Wet etching mask layer 6 Low temperature cured resin layer

Claims (7)

[Claims] The present invention relates to a metal conductive layer formed on a transfer mask for the purpose of improving heat radiation characteristics and durability of the mask when irradiating an electron beam.
cc and an electrical resistivity of 60 μΩ · cm (at2
5 ° C.) and a thermal conductivity of 0.04 cal / cm /
A transfer mask characterized by being made of a conductive material that is larger than cm ² / sec / ° C., is not magnetic, and can be dry-etched. A conductive layer formed on a surface of the substrate;
A support frame formed by processing a surface and a support frame supported by the support frame.
And a through-hole formed in the thin film portion.
In the transfer mask, the conductive layer has an actual density of a metal element of more than 6 g / cc.
Less than 60μΩ · cm (at 25 ℃)
The thermal conductivity is 0.04 cal / cm / cm ^Two/ Se
larger than c / ° C, not magnetic, and dry
That it is made of a conductive material that can be etched
Characteristic transfer mask. 3. A supporting frame portion by etching the back surface of the substrate.
Forming a thin film portion supported by the support frame portion;
Forming a through hole in the thin film portion.
In the manufacturing method, at least a conductive layer is formed on the substrate surface.
Forming, and etching the conductive layer on the conductive layer.
Forming a masking layer and forming the conductive layer on the conductive layer.
Desired etching mask layer using lithography technology
Patterning into a shape of
Dry etching using the etched etching mask layer as a mask.
The conductive layer and substrate surface to a predetermined depth
And a process for continuously manufacturing the transfer mask.
In the transfer mask obtained through the method, the conductive layer has a real density of the metal element of more than 6 g / cc.
Less than 60μΩ · cm (at 25 ℃)
The thermal conductivity is 0.04 cal / cm / cm ^Two/ Se
larger than c / ° C, not magnetic, and dry
That it is made of a conductive material that can be etched
Characteristic transfer mask. 4. The method according to claim 1, wherein the conductive layer is made of any one of tungsten, tantalum, molybdenum, and iridium.
4. The transfer mask according to claim 1, wherein the transfer mask is made of an alloy containing these metals or an intermetallic compound of these metals. 5. The transfer mask according to claim 1, wherein the conductive layer is formed by a sputtering method or a CVD method. 6. The transfer mask according to claim 2, wherein said support frame portion and said thin film portion are obtained by processing a silicon substrate. 7. The method according to claim 1, wherein the substrate is a silicon substrate, and is a transfer mask obtained by continuously etching the conductive layer and the silicon substrate with the same etching gas. The transfer mask according to any one of the above.