JP3246849B2 - Transfer mask - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transfer mask used for electron beam exposure and ion beam exposure.

[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, as a mask for electron beam exposure and ion beam exposure, a transfer mask in which a pattern to be exposed is formed by making a hole (opening) in a metal foil such as Si, Mo, Al, or Au. (Stencil mas
Although k) has been developed and is being put into practical use, it has not yet reached 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 in recent years, and has emerged as a next-generation LSI technology. The drawing method using the partial batch exposure is a direct drawing method (so-called single-stroke writing method) in which an exposure pattern is scanned with an electron beam (thin beam spot) that has already been put into practice and drawing is performed.
Is a method devised to cope with an extremely long drawing time and a low throughput, which is a problem in the method described above, and a high-speed drawing is possible as compared with a direct drawing method using a variable rectangle.

[0005] Transfer masks used for such partial batch exposure have been conventionally manufactured by various methods.
In general, it is manufactured by processing a silicon substrate (a commercially available silicon wafer or the like) from the viewpoint of processability and strength. Specifically, for example, the back surface of the silicon substrate is etched to form a support frame portion and a thin film portion supported by the support frame portion,
A transfer mask is formed by forming a through hole in the thin film portion.

[0006] In such a transfer mask made of silicon alone, the silicon thin film portion in which an opening is formed as it is has poor durability against an electron beam. Therefore, gold (Au), tungsten or the like is usually provided on the silicon thin film portion. (W), a metal layer such as platinum (Pt) is formed to improve the durability of the mask during electron beam irradiation. In addition, since these metals are good conductors and have excellent electron conductivity and heat conductivity, they contribute to the prevention of beam shift due to charging (charge-up) and the effect of preventing thermal distortion of the mask due to heat generation. Furthermore, since these metals have excellent shielding properties against electron beams and act as energy absorbers, the silicon thin film portion can be made thinner, so that the opening accuracy is improved and the effect of the opening side walls on the electron beams is reduced. Can be reduced.

[0007]

However, the metal layer formed on the silicon thin film portion has the following problems.

That is, in Au, the linear expansion coefficient of Au is significantly different from that of silicon.
Since the mask is distorted by stress or a diffusion reaction occurs in which Au diffuses into silicon, there is a problem that the stability and durability of the mask are lacking. Further, since it is difficult to dry-etch Au, it is only possible to form an Au layer by a thin-film forming method after forming an opening, and there is a problem that the opening accuracy is impaired and the process is greatly restricted.

[0009] Further, W has almost the same linear expansion coefficient as silicon, but is excellent in stability because it easily forms an oxide layer on the surface and has poor chemical resistance to acids. There is a problem that it is difficult to remove organic substances such as carbon adhered as contaminants in a vacuum apparatus by acid cleaning. Further, similarly to Au, there is a problem that a diffusion reaction occurs with silicon.

Furthermore, Pt has a problem that the thermal conductivity is lower than that of silicon and the coefficient of linear expansion is twice as large as that of silicon. . Further, similarly to Au, since dry etching is difficult, there is a problem that aperture accuracy is impaired and process restrictions are large.

The present invention has been made in view of the above problems, and has as its object to provide a transfer mask having a metal layer satisfying various required characteristics as a metal layer and having excellent practicability such as durability. I do.

[0012]

In order to achieve the above object, the present invention is applied to electron beam exposure or ion beam exposure of the present invention.
Transfer mask that is a transfer mask obtained by forming a through hole in the thin film portion supported by the support frame portion, at least, configure provided iridium layer on the transfer surface of the mask, or,
A transfer mask in which a through-hole is formed in a thin film portion supported by a support frame portion, at least a laminated layer including a tungsten layer / iridium layer or an iridium layer / tungsten layer / iridium layer on the transfer mask surface, or The structure is such that a laminated layer including a tantalum layer / iridium layer or an iridium layer / tantalum layer / iridium layer is provided.

The electron beam exposure or ion beam of the present invention
The transfer mask used for the system exposure is a structure in which the iridium layer or the laminated layer is formed also on the side surface and / or the back surface of the transfer mask in the transfer mask, the iridium layer is a compound layer containing iridium, or iridium. Or an iridium layer having a tilted structure such that the substrate interface is IrO ₂ and the X amount of IrO x becomes zero as the deposition proceeds, and the thin film portion supported by the support frame portion The transfer mask formed with the through holes is formed by etching a silicon substrate, an SOI substrate, or a SIMOX substrate, or the transfer mask is formed in a thin film portion supported by a support frame portion. After forming a transfer mask formed by forming an iridium layer or a laminated layer by a thin film forming method, or forming a through hole On the substrate after forming the iridium layer or laminated layers, it is constituted is obtained by forming a through hole.

Hereinafter, the present invention will be described in detail. The transfer mask of the present invention is, for example, as shown in FIG.
2 is a transfer mask in which a through-hole (opening 11) is formed in the thin film portion 13 supported by the transfer mask 2, and has a configuration in which at least the iridium layer 2 is provided on the transfer mask surface.

The transfer mask of the present invention is prepared by processing a silicon substrate or the like by various conventionally known methods to produce a transfer mask made of silicon or the like in which a through hole is formed in a thin film portion supported by a support frame. It can be obtained by forming iridium (layer) on the surface of the transfer mask by a thin film forming method.

The transfer mask of the present invention can also be obtained by forming a through hole after forming an iridium layer on the substrate before forming the through hole.

The iridium layer 2 does not need to be formed on the entire surface of the transfer mask, and may be formed on the surface of the thin film other than the through-hole.

The transfer mask formed by forming a through-hole in the thin film portion supported by the support frame may be a transfer mask manufactured by various conventionally known methods. The configuration and the like are not particularly limited.
The method for manufacturing the transfer mask of the present invention will be described later in detail.

The iridium (Ir) layer formed on the surface of the transfer mask satisfies all the characteristics required for the metal layer formed on the surface of the transfer mask, and has extremely excellent material characteristics.

The material properties of iridium (density, electrical resistance,
Table 1 shows the thermal conductivity and the coefficient of linear expansion. For comparison, Table 1 also shows the material properties of silicon (Si) as a mask material and other metal layer forming materials (Au, W, Pt). Ru (ruthenium), Os (osmium),
Re (rhenium) is easily oxidized on the surface.

[0021]

[Table 1]

Here, since iridium has a high density, it is possible to reduce the depth of penetration of electrons (ie, the range distance) with respect to the acceleration voltage when irradiating an electron beam. The iridium layer is a layer formed of iridium alone, a compound layer containing iridium (eg, an oxide, a nitride, a carbide, or the like) or an alloy layer containing iridium (eg, tungsten, tantalum, molybdenum, platinum, or osmium). And the like, or intermetallic compounds with these metals, etc. ). This makes it possible to control the material characteristics of the iridium layer, the adhesion to the substrate, and the like.

The iridium layer may be a single layer of the iridium layer, or may be a laminated layer composed of an iridium layer / tungsten layer / iridium layer (sandwich structure) or a tungsten layer / iridium layer. The iridium layer may have a tilted structure in which the substrate interface is IrO ₂ and the X amount of IrO x becomes zero as the deposition proceeds. Thus, the surface oxidation preventing effect, the adhesion to the substrate, the diffusion preventing effect, and the like can be controlled.

Further, a buffer layer such as an oxide or a metal may be provided between the Si layer and the Ir layer to control the adhesion to the substrate.

The thickness of the iridium layer is 0.02 to 5 μm
(200 to 50,000 angstroms). The thickness of the iridium layer is 0.02 μm
If it is thinner, the durability against electron beams will be poor, and
If it exceeds, it becomes difficult to form a film, it is difficult to control the film stress, and it becomes difficult to perform high-precision dry etching.

The method for forming the iridium layer is not particularly limited, and examples thereof include a thin film forming method such as an ion beam evaporation method, a vacuum evaporation method, a sputtering method, and an ion plating method. The method for forming the iridium layer is appropriately selected in consideration of film quality (density, crystal structure, defect-freeness, and the like of the film), cost, and the like.

The formation position of the iridium layer and the like may be on the side and / or the back side of the transfer mask (including the tapered portion on the back surface of the substrate and the back side of the thin film portion) in addition to the position on the transfer mask surface.
Alternatively, it may be formed on the side wall of the opening. This is because, when a transfer mask is manufactured using an SOI substrate or the like, the iridium layer on the surface of the transfer mask is electrically insulated by the SiO ₂ layer which is a dielectric, so that charge-up easily occurs and the SiO ₂ layer Has poor thermal conductivity, so the mask may generate heat. Therefore, to solve these problems, Si
This is because an iridium layer is also formed on the side surface and the back surface (including the back surface side of the thin film portion) of the transfer mask where the O ₂ layer is not formed, and the iridium layer is brought into conduction (contact) with the front surface side to address these problems.

In this case, for example, Ir / W / I is applied to the surface irradiated with the electron beam to prevent surface oxidation and diffusion.
Since a plurality of layers of a sandwich structure made of r are formed, and there is no need to prevent diffusion on the other surface to which the electron beam is not irradiated, even if a plurality of layers made of W / Ir and a metal good conductor layer other than Ir are formed, Good.

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

As described above, the transfer mask of the present invention
Processing a silicon substrate etc. by various conventionally known methods,
After a transfer mask made of silicon or the like having a through hole formed in the thin film portion supported by the support frame portion is formed, iridium (layer) can be formed on the surface of the transfer mask by a thin film forming method. Here, the following methods are mentioned as conventionally known various methods.

For example, an SOI (Silicon on Insulat) having a structure in which _two silicon plates are bonded via an SiO ₂ layer.
or) a method of forming a silicon thin film portion using a substrate with an SiO ₂ layer as an etching stop layer (etching stopper layer) (Japanese Patent Laid-Open No. Hei 6-130655), and a method of forming an opening (opening) pattern portion using a silicon substrate. A method of forming by electric discharge machining (JP-A-5-217876), or a method of applying a photosensitive glass on a silicon substrate and using the photosensitive glass as a mask material to omit the resist process (JP-A-4-240719) No.) and the like.

[0032] Among these various production methods,
Considering the durability of the thin film portion during the production of the transfer mask and the processing accuracy of the opening, an SOI substrate is used as the substrate.
Generally, a method is used in which the opening pattern portion is processed with high precision by dry etching, and the back surface portion of the substrate corresponding to the opening is processed by wet etching (wet etching). More specifically, for example, Si / SiO ₂
/ SOI substrate having a multilayer structure of
After forming a dry etching (trench etching) mask layer made of SiO ₂ on the side of the opening pattern forming surface of the I-substrate, the entire substrate is covered with a silicon nitride layer. There is a method of forming a thin film portion by wet etching, removing the silicon nitride layer, and then performing dry etching on the opening pattern side.

On the contrary, it is also possible to use a method in which the opening sequence is processed first and then the back surface of the substrate is processed by changing the process order. Further, a method using a boron layer as an etching stopper layer can also be used (Japanese Patent Laid-Open No.
No. -76216).

The transfer mask of the present invention can also be obtained by forming a through hole after forming an iridium layer on the substrate before forming the through hole. This manufacturing method (hereinafter, referred to as the present method) is a method previously filed by the present applicant and will be described in detail below.

Although the present method includes a plurality of steps and the order of these steps can be arbitrarily determined according to the purpose, the description will be made in accordance with one of the steps for convenience of explanation.

FIG. 3 is a process explanatory view showing an example of a process for manufacturing a transfer mask. As shown in FIG. 3, first, an iridium layer 2 is formed on the surface of the substrate 1 (FIG. 3A) (FIG. 3).
(B)). Here, as the substrate material, Si, Mo, A
l, Au, Cu, etc., from the viewpoint of chemical resistance, processing conditions, dimensional accuracy, etc., a silicon substrate, SOI substrate, SIMOX in which oxygen ions are implanted at a high concentration into a silicon substrate or the like to form an oxide film by heat treatment. (Separation by im
It is preferable to use a planted oxygen (substrate) substrate or the like. Note that when a silicon substrate doped with phosphorus or boron is used, electron conductivity and the like of the silicon substrate can be improved.

The iridium layer 2 is formed by using the above-mentioned various thin film forming methods.

Next, an SiO ₂ layer (an iridium layer etching mask layer) 3 is formed on the iridium layer 2 (FIG. 3C). Here, SiO ₂ is formed only on the iridium layer _2.
Although the layer 3 may be formed, a well-balanced thickness (for example, 0.5 to 3.
0 μm).

As a method for forming the SiO ₂ layer, a sputtering method, a vapor deposition method, a thermal oxidation method, a CVD method, or an SOG (spin
On-glass), photosensitive glass, photosensitive SOG, and the like.

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. 3 (c)).

In this case, considering the pattern accuracy, S
The etching of the iO ₂ layer 3 is performed using a fluorocarbon gas (C
It is preferable to perform dry etching using F ₄ , C ₂ F ₆ , CHF ₃ or the like as an etching gas.

Next, after the resist is removed, the iridium layer 2 and the surface of the substrate 1 are trench-etched (etched into grooves) by dry etching using the patterned SiO ₂ layer 3 as a mask.
The iO ₂ pattern is transferred to these (FIG. 3 (d)).

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 dry etching is not particularly limited. For example, as an etching gas for iridium, a fluorocarbon-based gas (SF ₆
/ O ₂ mixed gas, SF ₆ / Cl ₂ mixed gas, CF ₄ / O ₂ mixed gas, CBrF ₃ gas, etc.), and HBr gas, Cl ₂ / O ₂ mixed gas, S
iCl ₄ / N ₂ mixed gas and the like. Note that the iridium layer and the silicon substrate may be continuously etched with the same etching gas using SF ₆ gas or the like.

By continuously etching the iridium layer and the silicon substrate as described above, the opening including the iridium layer can be formed in one step by continuous dry etching in a short time. In addition, it can be performed with high precision and easily.

Next, after removing the unnecessary SiO ₂ layer 3 with a stripping solution (buffered hydrofluoric acid, dilute hydrofluoric acid, etc.), a wet etching mask layer 4 is formed on the back surface of the substrate (FIG. 1).
(D)) The wet etching mask layer 4 is patterned by lithography (FIG. 1)
(E)).

However, when the SiO ₂ layer is also formed on the back surface, the SiO ₂ layer on the back surface can be used as it is as a wet etching mask layer depending on the type of the wet etching solution. SiO
_It may be used as it is without removing the _two layers.

Here, the wet etching mask layer 4
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.

As the wet etching mask layer 4, an inorganic layer such as SiO ₂ , SiC, Si 3 N 4, sialon (composite mixture of Si and Al), and SiON can be used.

The wet etching mask layer 4 may be formed by a thin film forming method such as a sputtering method, a vapor deposition method, or a CVD method. If the film quality is poor, an etchant is impregnated into the silicon substrate to etch holes (etch pits). The sputtering method or the CVD method at 350 ° C. or lower is preferred from the viewpoint of avoiding the occurrence of cracks, and from the viewpoint of avoiding damage such as cracks due to thermal stress in high-temperature film formation.

The thickness of the wet etching mask layer 4 is
Suitably, it is in the range of 0.1 to 1 μm. If the thickness of the wet etching mask layer 4 is less than 0.1 μm, the silicon substrate cannot be completely covered. If the thickness exceeds 1 μm, 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 4 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 4 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 is used as an etchant for titanium, and ceric ammonium nitrate / perchlorate 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 5 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 5 plays a role as a protective layer in a portion 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 fluorine resin, ethylene resin, propylene resin, silicon resin, butadiene resin, and styrene resin.

A low-temperature cured resin layer 5 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.

It is appropriate that the thickness of the low-temperature curing resin layer 5 is 30 μm or more. The thickness of the low-temperature curing resin layer 5 is 3
If the thickness is less than 0 μm, the durability to an etching solution and the function as a protective layer become poor.

The low-temperature curable resin layer does not affect other parts due to thermal stress when it is formed or removed.
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 5 has been formed is immersed in an etchant, and the back surface of the substrate is etched (FIG. 1F). Here, examples of the etchant include an aqueous alkaline solution such as KOH and NaOH, an aqueous alkaline solution containing alcohol and the like, and an alkaline solution such as an organic alkali.

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 this method, 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 therefore, bare Silicon (ordinary silicon substrate) can be used, which can contribute to cost reduction.

Finally, the unnecessary low-temperature curing resin layer 5 is removed with an organic solvent or the like, and the wet etching mask layer 4 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 method 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. For example, the back surface processing may be performed first, and the opening may be formed later.

Further, a transfer mask can be manufactured by combining some of the steps of the present method and a conventionally known step (including a part) of manufacturing a transfer mask.

The present invention will be described below in more detail with reference to examples.

Example 1 FIG. 1 is a process explanatory view showing an example of a process for manufacturing a transfer mask of the present invention. As shown in FIG. 1, an inorganic layer (SiO ₂ ) is formed on both sides of a phosphorus (P) -doped silicon substrate 1 (FIG. 1A).
Layer) (not shown), pattern the inorganic layer by lithography, dry-etch from the front side to form openings 11, and wet-etch from the back side to form the support frame 12 Was formed, and the unnecessary inorganic layer was removed with buffered hydrofluoric acid or the like to obtain a transfer mask consisting only of silicon (FIG. 1B).

Next, the iridium layer 2 was formed to a thickness of 1 μm on the obtained transfer mask surface by electron beam (EB) evaporation.
To form a transfer mask.

The obtained transfer mask was mounted on an electron beam exposure apparatus, and a drawing test was performed. As a result, it was confirmed that the transfer mask was excellent in drawing accuracy and durability and high in practicality.

Embodiment 2 FIG. 2 is a process explanatory view showing another example of the process of manufacturing the transfer mask of the present invention. As shown in FIG. 2, an etching mask layer patterned by lithography is formed on the back surface of the boron (B) -doped silicon substrate 1 (FIG. 2 (a)), and wet etching is performed from the back surface side to form a thin film. The part 13 was formed (FIG. 2B).

Next, an Ir2a / W2b / Ir2c layer 2 having a sandwich structure is formed on the surface of the substrate 1 (FIG. 2C). On the Ir / W / Ir layer 2, SiO ₂
The layer 3 was formed, and the SiO ₂ layer 3 was patterned by using a lithography technique using a resist and a dry etching technique (FIG. 2D).

Thereafter, using the patterned SiO ₂ layer 3 as a mask, Ir / W
The / Ir layer 2 was etched (FIG. 2E), followed by trench etching on the surface of the silicon substrate 1 to form an opening pattern (FIG. 2F). In addition, Ir / W
A fluorocarbon-based gas (CF ₄ / O ₂ ) was used as an etching gas for the / Ir layer 2, and a Cl ₂ / SF ₆ mixed gas was used as an etching gas for the surface of the silicon substrate 1.

Finally, the unnecessary SiO ₂ layer 3 was removed with buffered hydrofluoric acid or the like to obtain a transfer mask (FIG. 1).
(F)).

In the transfer mask, since the opening including the metal layer is formed by continuous dry etching, a transfer mask having an opening with higher precision than that obtained by coating the metal layer after forming the opening is obtained. I was able to. The obtained transfer mask was mounted on an electron beam batch exposure apparatus, and a drawing test was performed. As a result, it was confirmed that the transfer mask had excellent drawing accuracy and durability and was highly practical.

Embodiment 3 FIG. 3 is a process explanatory view showing another example of the process of manufacturing the transfer mask of the present invention. As shown in FIG. 3, on the surface of the phosphorus (P) -doped silicon substrate 1 (FIG. 3 (a)), the substrate interface is IrO ₂ , and is tilted so that the X amount of IrO x becomes zero as the deposition proceeds. An iridium (oxidized to non-oxidized) layer 2 was formed with a thickness of 2 μm by a sputtering method. (FIG. 3 (b)). When the substrate interface is made of IrO ₂ in this manner, the adhesion characteristics to the substrate are further improved, and since the surface is made of Ir, various required characteristics as a metal layer are excellent.

Next, a SiO ₂ layer 3 was formed on the iridium layer 2 to a thickness of 3 μm, and this SiO ₂ layer 3 was patterned by using a lithography technique using a resist and a dry etching technique. (FIG. 3 (c)).

Thereafter, the patterned SiO 2
_{Using the second} layer 3 as a mask, the iridium layer 2 is etched by dry etching.
An opening pattern was formed by performing trench etching on the surface (FIG. 3D). Note that a fluorocarbon-based gas (SF ₆ / Cl ₂ ) is used as an etching gas for the iridium layer 2.
And a mixed gas of SiCl ₄ / SF ₆ / Cl ₂ was used as an etching gas for the surface of the silicon substrate 1.

Next, an SiC layer (etching mask layer) 4 having a thickness of 2000 angstroms is formed on the back surface of the substrate 1 and a rubber-based resin (ethylene / propylene or the like) is formed on the front and side surfaces of the substrate as a protective layer against etching.
Is applied in a thickness of 300 μm to form a resin layer 5,
The resin layer 5 was cured by heating at 0 ° C. (FIG. 3)
(E)).

The SiC layer 4 formed on the back surface of the substrate 1 was patterned using a lithography technique using a resist and a dry etching technique (FIG. 3).
(E)). Using the patterned SiC layer 4 as a mask, the back surface of the silicon substrate 1 was wet-etched until it reached the opening pattern (FIG. 3 (f)).

Finally, the unnecessary SiC layer 4, Si
The O ₂ layer 3 and the resin layer 5 were removed to obtain a transfer mask (FIG. 3F).

In the transfer mask, since the opening including the metal layer is formed by continuous dry etching, a transfer mask having an opening with higher precision than when coating the metal layer after forming the opening is obtained. I was able to.

The obtained transfer mask was mounted on an electron beam batch exposure apparatus, and a drawing test was performed. As a result, it was confirmed that the transfer mask was excellent in drawing accuracy and durability and high in practicality.

The erosion (especially the opening) of the etching solution during the wet etching of the back surface of the substrate was completely prevented by the low-temperature curing resin layer. In addition, the influence of thermal stress could be avoided throughout the entire process, and no damage or the like occurred during the process, and the transfer mask could be manufactured stably.

Embodiment 4 FIG. 4 is a process explanatory view showing another example of the process of manufacturing the transfer mask of the present invention. As shown in FIG. 4, the entire surface (all surfaces) of the phosphorus (P) -doped silicon substrate 1 having a thickness of 500 μm has C
An SiC layer (etching mask layer) 4 having a thickness of 0.2 μm was formed by the VD method (FIG. 4A).

Subsequently, the back surface SiC layer 4 is patterned by lithography using a resist, and the patterned back surface SiC layer 4 is
The back surface of the substrate 1 was etched into a predetermined size and shape with an OH aqueous solution to form a support frame portion and a thin film portion (FIG. 4B).

Next, after removing the SiC layer 4, the substrate 1
An SiO ₂ layer 3 having a thickness of 2 μm was formed on the surface by a sputtering method, and patterning was performed on a region on the thin film portion of the SiO ₂ layer 3 using a lithography technique using a resist and a dry etching technique (FIG. 4). (C)).

Thereafter, the patterned SiO 2
_{Using the second} layer 3 as a mask, the thin film portion of the silicon substrate 1 was etched by dry etching to form an opening pattern (FIG. 4D).

Further, the unnecessary SiO ₂ layer 3 was removed with buffered hydrofluoric acid or the like to obtain a transfer mask consisting only of silicon (FIG. 4E).

Next, an iridium layer 2 having a thickness of 1 μm was formed on the obtained transfer mask surface by ion plating to obtain a transfer mask (FIG. 4F).

The obtained transfer mask was mounted on an electron beam exposure apparatus, and a drawing test was carried out. As a result, it was confirmed that the transfer mask had excellent drawing accuracy and durability and was highly practical.

Embodiment 5 FIG. 5 is a process explanatory view showing another example of the process of manufacturing the transfer mask of the present invention. As shown in FIG. 5, a 3 μm thick SiO 2 layer 3 was formed on the entire SOI substrate 1 (entire surface) by a CVD method (FIG. 5A).

Subsequently, the back surface SiO 2 layer 3 is patterned by a lithography method using a resist, and using the patterned back surface SiO 2 layer 3 as a mask, ethylenediamine / pyrocatechol (catechol)
The back surface of the substrate 1 was etched to a predetermined size and shape with a mixed aqueous solution of / water to form a support frame portion and a thin film portion (FIG. 5B).

Next, patterning was performed on a region on the thin film portion of the SiO ₂ layer 3 on the surface of the substrate by using a lithography technique using a resist and a dry etching technique (FIG. 5C).

Thereafter, the patterned SiO 2
_{Using the two} layers 3 as a mask, the thin film portion of the silicon substrate 1 was etched by dry etching to form an opening pattern (FIG. 5D).

Further, the unnecessary SiO ₂ layer 3 and the SiO ₂ layer in the SOI were removed with buffered hydrofluoric acid or the like to obtain a transfer mask made of silicon (FIG. 5E).

Next, an iridium layer 2 having a thickness of 0.5 μm was formed on the obtained transfer mask surface by a vacuum evaporation method to obtain a transfer mask (FIG. 5F).

The obtained transfer mask was mounted on an electron beam batch exposure apparatus, and a drawing test was performed. As a result, it was confirmed that the transfer mask was excellent in drawing accuracy and durability and high in practicality.

While the present invention has been described with reference to the preferred embodiments, the present invention is not necessarily limited to the above-described embodiments. For example, similar results were obtained when a SIMOX substrate was used instead of the SOI substrate. Also, when the iridium layer was formed on the mask side surface and the back surface in addition to the mask surface, an excellent charge-up preventing effect was exhibited.

The transfer mask of the present invention can be used as an ion beam exposure mask in addition to an electron beam exposure mask.

[0099]

As described above, the transfer mask of the present invention has a metal layer that satisfies various required characteristics as a metal layer, and is excellent in practicality such as durability.

[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.

FIG. 5 is a process explanatory view showing another example of a process of manufacturing a transfer mask according to the present invention.

[Explanation of symbols]

Reference Signs List 1 substrate 2 iridium layer 3 SiO ₂ layer 4 etching mask layer 5 resin layer 11 opening 12 support frame 13 thin film

 ──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-4-94523 (JP, A) JP-A-61-269313 (JP, A) JP-A-60-93440 (JP, A) JP-A-4-94 711 (JP, A) JP-A-2-123730 (JP, A) JP-A-55-161242 (JP, A) JP-A-62-263636 (JP, A)

Claims (6)

(57) [Claims] 1. A transfer mask obtained by forming a through hole in the thin film portion supported by the support frame portion, at least, an electron beam exposure or ion, characterized in that a layer of iridium on the transfer surface of the mask For beam exposure
Transfer mask is needed. 2. A transfer mask formed by forming a through hole in a thin film portion supported by a support frame portion, wherein at least a tungsten layer / iridium layer or an iridium layer / tungsten layer / iridium layer is formed on a surface of the transfer mask. Electron beam exposure or lamination provided with a laminated layer consisting of a tantalum layer / iridium layer or a laminated layer composed of an iridium layer / tantalum layer / iridium layer.
Is a transfer mask used for ion beam exposure . 3. The electron beam exposure or ion beam according to claim 1, wherein the iridium layer or the laminated layer is formed also on the side and / or the back side of the transfer mask.
Transfer mask used for electron beam exposure . 4. The iridium layer is a compound layer containing iridium, an alloy layer containing iridium, or
As the substrate interface is IrO ₂ and the deposition proceeds, IrOx
4. An electron beam according to claim 1, wherein the iridium layer has an inclined structure such that the X amount of the iridium becomes zero.
A transfer mask used for exposure or ion beam exposure . 5. A transfer mask comprising a through-hole formed in a thin film portion supported by the support frame portion, wherein the transfer mask is a silicon substrate, SOI
Claims 1 is a substrate or SIMOX substrate which is formed by etching four-electron beam exposure or b according
Transfer mask used for on-beam exposure . 6. The transfer mask according to claim 1, wherein
After forming a transfer mask in which a through hole is formed in the thin film portion supported by the support frame portion, an iridium layer or a laminated layer is formed by a thin film forming method, or an iridium layer or a laminated layer is formed on a substrate before the through hole is formed. After forming the layer, electron beam exposure or characterized in that the through hole is formed
Transfer mask used for ion beam exposure .