JP2007220955A - Charged beam forming mask, and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a charged beam forming mask in which an aperture pattern for charged beam forming has fine dimensions and a good positional accuracy, and which includes no pattern vertices having any roundness. <P>SOLUTION: In the charged beam forming mask having a polygon aperture formed in a thin film of a multilayer structure, overlapped parts of different openings formed in the respective layers of the film form the polygonal aperture, and vertices of the polygonal aperture are formed at points between overlapped sides of the openings of the thin film layers, so that the vertices of the beam forming pattern are not rounded. Since the aperture is formed by positioning lithography and by dry etching, the mask has such a beam forming pattern as to have excellent positional and dimensional accuracies. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a charged beam shaping mask used for an electron beam exposure apparatus, an ion beam exposure apparatus, and the like, and a method for manufacturing the same.

  Conventionally, in semiconductor device manufacturing and photomask manufacturing, a pattern forming method using a charged beam such as an electron beam exposure apparatus or an ion beam exposure apparatus is used. That is, in order to form a pattern with a charged beam, a charged beam shaping mask having a through-hole for shaping the charged beam into a predetermined shape is used. With the recent miniaturization of semiconductor devices and photomasks, The accuracy requirements for the position and shape of through-holes are becoming stricter.

  In general, a charged beam shaping mask is used in which a through hole for beam shaping is provided on a metal plate such as tantalum or molybdenum as a charged beam shaping mask by electric discharge machining or cutting. Alternatively, a mask is used in which a plurality of metal plates each having a through hole are bonded to form a through hole having a desired shape.

However, in the electric discharge machining or cutting of tantalum or molybdenum, it is difficult to make the through hole fine, and there is a problem that the apex portion of the polygonal through hole is rounded. For this reason, there is a problem that a fine beam having no roundness at the apex cannot be formed.
In addition, in the bonding method, since the vertex of the polygon is formed by overlapping the plate (through hole) and the plate (through hole), it is possible to form a vertex with no roundness. As a result, it is difficult to miniaturize the holes and the position and dimensions are difficult to control. In addition, when a polygon other than a rectangle is formed, there is a problem that shape control becomes more difficult.

With regard to the problem of rounding of the through-hole apex by such electric discharge machining and cutting, rounding at the apex is made by processing different rectangles from the front and back on a single plate and forming a rectangle at the overlapping part of the front and back openings. There has been proposed a method of manufacturing a beam shaping mask having an opening without a gap (see, for example, Patent Document 1).
In addition, a method has been proposed in which the processing shape of the front and back surfaces is a triangle and a hexagonal opening is formed by overlapping the shapes (for example, see Patent Document 2).
JP 2001-244171 A JP 2004-266184 A

  However, in the methods as disclosed in Patent Documents 1 and 2 described above, since the opening on the front and back of a single plate is performed by electric discharge machining or cutting, it is difficult to form a fine opening, and the opening size and opening It is difficult to control the position with high accuracy.

Therefore, in order to solve these problems, a fine resist pattern with high precision is formed on a thin film material such as silicon by photolithography or electron beam lithography, and an accurate opening is formed by dry etching using this resist pattern as a mask. A method of forming is possible. According to this method, a charged beam shaping mask having an arbitrary polygonal opening can be easily produced.
However, since a vertex having no roundness cannot be formed even by lithography or dry etching, there is a problem that the vertex of the shaped beam is rounded as a result.

  Accordingly, an object of the present invention is to provide a charged beam shaping mask that can form a highly precise shaped beam and a method for producing the same, which can form a polygonal opening, in particular, an apex portion having no roundness.

In order to achieve the above-described object, the present invention provides a charged beam shaping mask having a polygonal aperture through which a charged beam passes through a laminated film having a structure in which a plurality of thin films are laminated, wherein the polygonal aperture is the laminated layer. The through holes having different shapes formed in the respective thin film layers of the film are overlapped, and the apex of the polygonal opening is formed by intersecting the sides of the through holes formed in the respective thin film layers. It is characterized by that.
The present invention also relates to a method of manufacturing a charged beam shaping mask having a polygonal aperture through which a charged beam is transmitted in a laminated film having a structure in which a plurality of thin films are laminated, wherein the first thin film layer is laminated on a support substrate. Forming a first through hole, laminating a second thin film layer on the first thin film layer via a buried layer to form a second through hole, the support substrate and the buried Forming a charged beam shaping mask and a polygonal opening to remove the layer, and forming the vertex of the polygonal opening by intersecting the sides of the through holes formed in each thin film layer. It is characterized by that.

  According to the charged beam shaping mask and the manufacturing method thereof of the present invention, there is an effect that it is possible to provide a charged beam shaping mask having an arbitrary polygonal transfer pattern with high accuracy and fineness without any roundness at the apex of the polygonal opening.

  An embodiment of the present invention is a charged beam shaping mask having a polygonal opening in a thin film having a multilayer structure, and the charged beam through-hole is processed by photolithography or electron beam lithography and dry etching so as to be fine, dimension and position. A through-hole with high accuracy is provided, and a polygonal opening is formed at the overlapping portion of different through-holes formed in each thin film layer, and a polygon is formed at a position where the sides of the through-hole formed in each thin film layer overlap. By forming the apex of the opening, a charged beam shaping mask having an opening with no roundness at the apex of the polygonal opening is produced.

Hereinafter, a charged beam shaping mask and a manufacturing method thereof according to the present embodiment will be described.
FIG. 1 is a conceptual diagram showing an example of a plurality of thin film layers constituting a charged beam shaping mask according to the present embodiment. FIG. 1 (a) is a schematic plan view, and FIG. 1 (b) is a diagram in FIG. 4 is a schematic cross-sectional view of the auxiliary line 4.
In this example, the first thin film layer 1 in which the first through hole 11 is formed is formed, and the second thin film in which the second through hole 12 different from the first through hole 11 is formed thereon. Layer 2 is formed.
The third through-hole 13 is formed by the overlap of the first through-hole 11 and the second through-hole 12, and the charged beam shaping mask 3 according to the present embodiment is manufactured.
Each side constituting the third through-hole 13 is constituted by the side of the first through-hole 11 or the second through-hole 12, and each vertex of the third through-hole 13 is the first through-hole 11. And the overlapping of the sides of the second through-hole 12. Therefore, the 3rd penetration port 13 is formed in the polygonal shape which has a vertex without a roundness.

FIG. 2 is a partial cross-sectional view showing an example of a method for manufacturing a charged beam shaping mask according to the present embodiment.
Here, an example is shown in which two different through holes formed in two different layers are stacked to form a through hole having a fine and highly accurate dimension and position with a rounded apex. It is possible to form more complicated shapes by increasing the number of layers.

Hereinafter, the manufacturing steps of this example will be sequentially described with reference to FIG.
First, as shown in FIG. 2A, a multilayer substrate 7 in which an etching stop layer 6 and a first thin film layer 1 are formed on one surface of a support substrate 5 is produced.
Next, as shown in FIG. 2B, the first through hole 11 and the alignment mark 14 are formed in the first thin film layer 1 by lithography such as photolithography and electron beam lithography and dry etching. . At this time, since etching is stopped at the etching stop layer 6, the etching does not reach the support substrate 5.
For dry etching, the dry etching method and conditions are not particularly limited. Examples of the dry etching apparatus include dry etching apparatuses using discharge methods such as RIE, magnetron RIE, ECR, ICP, NLD, microwave, helicon wave, and the like. As a method for forming the opening, ion beam etching can be preferably used in addition to dry etching.

  Next, as shown in FIG. 2C, the filling layer 8 is filled in the first through hole 11 and the alignment mark 14 by plating, and then the surface is polished and flattened. As this embedding method, in addition to the plating method, a plasma film forming method, a sputtering method, a CVD (Chemical Vapor Deposition) method, or the like can be suitably used. As the surface polishing method, mechanical polishing, chemical mechanical polishing (CMP) or the like is preferably used.

  Next, as shown in FIG. 2D, the buffer layer 9 is formed on the planarized surface by the CVD method. The buffer layer 9 is used as an etching stop layer when forming the second through hole 12 to the thin film layer 2 to be implemented in a later step. As a method for forming the buffer layer 9, in addition to the CVD method, a plasma film forming method, a sputtering method, a plating method, or the like can be suitably used.

  Next, as shown in FIG. 2E, the second thin film layer 2 is formed on the buffer layer 9 by the CVD method. As a film forming method, in addition to the CVD method, a plasma film forming method, a sputtering method, a plating method, or the like can be suitably used.

  Next, a step of exposing the alignment mark 14 formed on the first thin film layer 1 is performed. As shown in FIG. 2F, a photoresist 10 is applied on the second thin film layer 2, and the resist 15 around the alignment mark 14 is removed by photolithography.

Next, as shown in FIG. 2G, the second thin film layer 2 and the buffer layer 8 are removed by dry etching using the resist 10 as a mask, and the alignment mark 14 is exposed. As the dry etching apparatus, a dry etching apparatus using a discharge method such as RIE, magnetron RIE, ECR, ICP, NLD, microwave, helicon wave or the like is preferably used. As an etching method, in addition to dry etching, wet etching, ion beam etching, ultrasonic processing, or the like can be suitably used.
Next, as shown in FIG. 2H, the resist 10 is peeled off.

  Next, a resist pattern for forming the second through hole 12 is formed on the second thin film layer 2 by photolithography or electron beam lithography. At this time, since the resist pattern is formed by alignment lithography using the alignment mark 14, alignment with the first through hole can be performed with high accuracy. Next, as shown in FIG. 2I, the second through hole 12 is formed in the second thin film layer 2 by dry etching using the resist pattern as a mask. At this time, the etching is stopped at the etching buffer layer 9. As a method for forming the opening, ion beam etching can be preferably used in addition to dry etching.

  Next, as shown in FIG. 2J, a wet etching mask 16 such as silicon nitride or silicon oxide is formed on the entire surface of the substrate by CVD, and a pattern 17 for etching the back surface of the support substrate 5 is formed by photolithography. It is formed by dry etching. As a method for forming the pattern 17 for etching the support substrate 5, wet etching, ion beam etching, ultrasonic processing, and the like can be suitably used in addition to dry etching.

  Next, as shown in FIG. 2 (k), the opening 18 is formed in the support substrate 5 by wet etching by alkaline liquid immersion such as heated potassium hydroxide (KOH) aqueous solution or tetramethylammonium hydroxide (TMAH). Etching is stopped at the etching stop layer 6.

  Although an example of forming the substrate back surface opening by wet etching is shown here, the substrate back surface opening formation by dry etching is also possible. In this case, the etching mask may be formed at least on the back surface of the substrate, and a resist, silicon oxide, metal film, or the like can be suitably used as the etching mask. As the dry etching method, side wall protective plasma etching, low temperature plasma etching, or the like can be suitably used.

  Next, as shown in FIG. 2 (l), the wet etching mask 16 is removed by wet etching, and the etching stopper layer 6, the buried layer 8, and the buffer layer 9 exposed at the bottom 19 of the opening 18 are removed, A charged beam shaping mask 3 according to the invention is obtained. A charged beam shaping mask 3 according to the present invention is formed by overlapping a first through hole 11 formed in the first thin film layer 1 and a through hole 12 formed in the second thin film layer 2. The through-hole 13 is provided, and the side of the third through-hole 13 is constituted by a part of the sides of the first through-hole 11 and the second through-hole 12, and the vertex of the third through-hole 13 is the first. The through-hole 11 and the second through-hole 12 overlap each other.

  By forming a metal film on the surface of the charged beam shaping mask 3 according to the present embodiment by sputtering or CVD, the conductivity and heat resistance of the charged beam shaping mask 3 can be improved. In this case, a metal film may be formed on at least one side of the third through-hole 13, but it is preferable to form a metal film on both sides in order to improve conductivity and heat resistance.

Next, a specific embodiment will be described using the method for manufacturing a charged beam shaping mask shown in FIG.
First, as shown in FIG. 2 (a), etching is stopped on one surface of a support substrate 5 made of single crystal silicon and having a thickness of 525 micrometers by thermal oxidation. A layer 6 is formed, and a silicon layer having a thickness of 10 μm is deposited on the etching stopper layer 6 by a CVD method to form the first thin film layer 1, thereby producing a multilayer substrate 7.

  Next, as shown in FIG. 2B, the first through hole 11 and the alignment mark are formed in the first thin film layer 1 by electron beam lithography and dry etching using a mixed gas of fluorine-based gas and chlorine-based gas. 14 is formed. At this time, the etching is stopped at the etching stop layer 6.

  For dry etching, the dry etching method and conditions are not particularly limited. Examples of the dry etching apparatus include dry etching apparatuses using discharge methods such as RIE, magnetron RIE, ECR, ICP, NLD, microwave, helicon wave, and the like. As a method for forming the opening, ion beam etching can be preferably used in addition to dry etching.

  Next, as shown in FIG. 2C, after filling the first through hole 11 and the alignment mark 14 with the nickel embedding layer 8 by plating, the surface is polished and flattened by CMP. As a filling method, in addition to the plating method, a plasma film forming method, a sputtering method, a CVD method, or the like can be suitably used.

  Next, as shown in FIG. 2D, a buffer layer 9 made of silicon oxide having a thickness of 1 micrometer is formed on the planarized surface by a CVD method. The buffer layer 9 is used as an etching stop layer when forming the second through-hole 12 to the thin film layer 2 made of silicon, which is performed in a later step. As a method for forming the buffer layer 9, in addition to the CVD method, a plasma film forming method, a sputtering method, a plating method, or the like can be suitably used.

  The material of the buffer layer is not particularly limited as long as it has high etching selectivity with respect to the thin film layer 2 to be formed later and can be easily removed finally. The buffer layer made of silicon oxide of this embodiment is suitable as a buffer layer because it has high etching selectivity with respect to silicon and can be easily removed with an aqueous hydrogen fluoride solution.

  Next, as shown in FIG. 2E, a silicon thin film is formed on the buffer layer 9 as the second thin film layer 2 to a thickness of 10 micrometers by the CVD method. As the film forming method, in addition to the CVD method, a plasma film forming method, a sputtering method, a plating method, or the like can be suitably used.

  Next, a step of exposing the alignment mark 14 formed on the first thin film layer 1 is performed. As shown in FIG. 2F, a photoresist 10 is applied on the second thin film layer 2 made of silicon, and the resist 15 around the alignment mark 14 is removed by photolithography.

  Next, as shown in FIG. 2G, the second thin film layer 2 made of silicon is removed by dry etching with a chlorine-based gas using the resist 10 as a mask, and then by dry etching with a fluorocarbon-based gas. The buffer layer 8 made of silicon oxide is removed, and the alignment mark 14 is exposed.

  As the dry etching apparatus, a dry etching apparatus using a discharge method such as RIE, magnetron RIE, ECR, ICP, NLD, microwave, helicon wave or the like is preferably used. As an etching method, in addition to dry etching, wet etching, ion beam etching, ultrasonic processing, or the like can be suitably used.

  Subsequently, a resist pattern for forming the second through hole 12 is formed on the second thin film layer 2 made of silicon by electron beam lithography. At this time, since the resist pattern is formed by alignment lithography using the alignment mark 14, alignment is performed with high accuracy such that the error between the first through hole and the position is 50 nanometers or less. Next, using the resist pattern as a mask, the second through-hole 12 is formed in the second thin film layer 2 made of silicon by dry etching using a mixed gas of fluorine-based gas and chlorine-based gas. At this time, the etching is stopped at the etching buffer layer 9 made of silicon oxide. As a method for forming the opening, ion beam etching can be preferably used in addition to dry etching.

  Next, as shown in FIG. 2H, the resist 10 is removed by ashing using oxygen plasma. Here, the resist is stripped by ashing using oxygen plasma, but wet etching using a resist stripping solution can also be suitably used.

  Next, as shown in FIG. 2 (i), a wet etching mask 16 made of a silicon nitride film is formed on the entire surface of the substrate by a CVD method to a thickness of 1 micrometer, and a pattern for etching the support substrate 5 made of silicon is etched. 17 is formed by photolithography and dry etching using a fluorine-based gas. As a method for forming the pattern 17 for etching the support substrate 5, wet etching, ion beam etching, ultrasonic processing, and the like can be suitably used in addition to dry etching.

  Next, as shown in FIG. 2 (k), the whole substrate is immersed in a tetramethylammonium hydroxide (TMAH) solution having a concentration of 20% heated to 85 ° C., and a support substrate made of silicon by anisotropic wet etching. 5 is formed with an opening 18. Since wet etching by TMAH has high etching selectivity with respect to silicon oxide, the etching is stopped at the etching stop layer 6 made of silicon oxide.

  Here, an example of forming an opening in the silicon support substrate 5 by wet etching is shown, but formation of a substrate back surface opening by dry etching can also be used suitably. In this case, the etching mask may be formed at least on the back surface of the substrate, and a resist, silicon oxide, metal film, or the like can be suitably used as the etching mask. As the dry etching method, side wall protective plasma etching, low temperature plasma etching, or the like can be suitably used.

  Next, the wet etching mask 16 made of a silicon nitride film is removed by wet etching with a phosphoric acid aqueous solution having a concentration of 85% heated to 160 ° C., and then the bottom 19 of the opening 18 is wet etched with a hydrofluoric acid aqueous solution having a concentration of 5%. The exposed etching stopper layer 6 and the buffer layer 9 made of a silicon oxide film are removed, and then the nickel buried layer 8 is removed by wet etching with a ferric chloride solution, and the charged beam according to the present invention shown in FIG. A molding mask 3 is obtained.

  In the case of a square opening, the opening of the charged beam shaping mask 3 obtained by this embodiment can be formed with a minimum dimension of up to 500 nanometers per side, the positional error is 50 nanometers or less, and is completely at the apex of the opening. There will be no roundness.

It is a conceptual diagram which shows an example of the some thin film layer which comprises the charged beam shaping mask by embodiment of this invention. It is a fragmentary sectional view which shows an example of the manufacturing method of the charged beam shaping | molding mask shown in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... 1st thin film layer, 2 ... 2nd thin film layer, 3 ... Charge beam transmission mask, 4 ... Auxiliary line, 5 ... Support substrate, 6 ... Etching stop layer, 7 ... Multilayer substrate 8 ... buried layer, 9 ... buffer layer, 10 ... photoresist, 11 ... first through-hole, 12 ... second through-hole, 13 ... third through-hole, 14 ... position Alignment mark, 15 ... resist around alignment mark, 16 ... wet etching mask, 17 ... support substrate etching pattern, 18 ... opening formed in support substrate, 19 ... bottom of support substrate opening.

Claims (4)

A charged beam shaping mask having a polygonal aperture through which a charged beam passes through a laminated film having a structure in which a plurality of thin films are laminated,
The polygonal opening is formed by overlapping through holes having different shapes formed in the thin film layers of the laminated film,
The vertex of the polygonal opening is formed by intersecting the side and side of the through-hole formed in each thin film layer,
Charged beam shaping mask characterized by that.   2. The charged beam forming mask according to claim 1, wherein the thin film layer is a silicon film layer, and the through hole is formed by a lithography process and a dry etching process for the silicon film layer. A method of manufacturing a charged beam shaping mask having a polygonal aperture through which a charged beam passes through a laminated film having a structure in which a plurality of thin films are laminated,
Laminating a first thin film layer on a support substrate to form a first through hole;
Stacking a second thin film layer on the first thin film layer via a buried layer to form a second through hole;
Removing the support substrate and the buried layer to form the charged beam shaping mask and a polygonal opening, and
The vertex of the polygonal opening is formed by crossing the side and the side of the through hole formed in each thin film layer,
A method of manufacturing a charged beam shaping mask. 2. The method of manufacturing a charged beam forming mask according to claim 1, wherein the thin film layer is a silicon film layer, and the through hole is formed by a lithography process and a dry etching process for the silicon film layer.

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