JP2005347078A - Fine manufacturing method of structure and masking method of the structure - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a diamond fine structure of dozens of nanometer sizes by relatively simple operation by adjusting its structure as masking layers formed on a diamond substrate and by etching by the masking, and by forming projections of arbitrary shapes on the diamond substrate. <P>SOLUTION: When forming a diamond structure having sharpness by applying masking on a diamond substrate and etching, etching is performed by making the masking a multiple layer structure and making the area of the masking on the side near the substrate smaller compared with the masking at the upper layer. Thereby, etching is performed which has an angle in which the width becomes wider as the etching depth becomes deeper, and the fine manufacturing method of the diamond structure having high sharpness is provided. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

The present invention adjusts the structure as a masking multilayer formed on a substrate made of a compound such as diamond, metal, silicon, GaAs, AlN, GaN, LaB ₆ , and etches them through masking. The present invention relates to a microfabrication method for forming protrusions having an arbitrary shape on a substrate and a masking method for the same.

In recent years, FED (field emission display) has been developed in which sharpened diamond is used and microelectrodes functioning as a field emission type electron-emitting device are two-dimensionally arranged.
This is characterized in that the deflection and convergence of electrons are almost unnecessary, so that it can be made thinner or flatter than a conventional display. Diamond is attracting attention because it has a very advantageous characteristic as an electron-emitting device having a negative electron affinity.

In order to give diamond an advantageous function as an electron-emitting device, it is necessary to sharpen the tip of the diamond like a cone. However, diamond generally has a problem that it is extremely difficult to process compared to metals, polymer organic materials, and other ceramic materials.
For this reason, several processing methods for sharpening the tip of the diamond like a cone have been proposed. For example, there is a proposal to form a large number of aligned diamond ridges on a diamond substrate by a mask etching method, and to form a diamond having a sharp tip by vapor deposition on this ridge (Patent Document 1). reference).

In this case, the selection and adjustment of the crystal orientation of the raised diamond is a very big problem. This is because the sharpened portion formed in the raised portion uses a pyramid portion where the ridgelines of the diamond crystal plane intersect, but the pyramid portion is governed by the plane orientation and is difficult to control.
As described above, when diamond (several tens of nanometers) is vapor-phase grown, there is a problem that it is actually very difficult to adjust the fine crystal orientation of the diamond on the raised portion of each diamond crystal. is there.

Similarly to Patent Document 1, a large number of aligned diamond columns are formed on a diamond substrate by a mask etching method as a first step, and then plasma etching or reactive ion etching is performed as a second step. It has been proposed to sharpen the tip of the columnar portion on the side opposite to the substrate (see Patent Document 2).
In this technique, the reactive ion etching used in the second step employs an etching method different from the etching used in the first step, that is, etching with a high rate of lateral etching rate, and thereby the tip of the columnar body. A sharp point is formed on the surface. However, there is a problem that the etching is naturally limited because it is limited to the etching that prioritizes lateral etching and makes it thinner.
JP 10-31735 A JP 2002-75171 A

The object of the present invention is to eliminate the above-mentioned problems of the prior art and to form a structure as a masking multilayer formed on a substrate made of a compound such as diamond, metal, silicon, GaAs, AlN, GaN, LaB ₆ or the like. By adjusting and etching through masking, protrusions of arbitrary shape are formed on a substrate made of a compound such as diamond, metal, silicon, GaAs, AlN, GaN, LaB ₆ and the size of several tens of nanometers It is an object of the present invention to obtain a fine structure made of a compound such as diamond, metal, silicon, GaAs, AlN, GaN, LaB ₆ or the like of any shape by a relatively simple operation.

As a result of diligent research in order to achieve the object of the present invention, a masking structure formed on a substrate made of a compound such as diamond, metal, silicon, GaAs, AlN, GaN, LaB ₆ or the like is formed into a multi-layer, By ingenuity, we have obtained knowledge that compounds such as diamond, metal, silicon, GaAs, AlN, GaN, LaB ₆ can be finely and arbitrarily controlled on the substrate with a relatively simple operation. .

The present invention is based on this finding.
1) By masking the substrate and making a sharp structure by etching, the masking is made into a multi-layer structure, and etching is performed by reducing the masking area closer to the substrate than the masking of the upper layer. The fine processing method of the structure with high sharpness characterized by performing etching at a wide angle as the etching depth becomes deep 2) Masking is performed on the substrate, and the shape of the truncated cone is provided by etching When manufacturing the structure, the masking has a multi-layer structure, and the masking area on the side closer to the substrate is larger than the masking of the upper layer, and etching is performed at an angle that becomes narrower as the etching depth increases. A method for microfabrication of a structure having a truncated cone shape characterized by 3) masking material The fine processing method of the structure according to 1 or 2 above, wherein the material is selected from metal, organic matter, glass and ceramics. 4) The masking material is composed of two or more materials having different etching rates. The structure according to any one of the above 1 to 3, wherein the masking areas of the upper layer and the lower layer are made different using the difference in etching rate between the upper layer and the lower layer of the mask. Microfabrication method 5) Etching the substrate by lie etching to form a minute convex portion 6) The microfabrication method of a structure according to any one of 1 to 4 above, wherein masking is performed on the substrate, A masking method used to fabricate a sharp structure by etching, in which etching is performed at a wider angle as the etching depth increases. A masking method for microfabrication of a structure, characterized in that the masking has a multilayer structure, and the masking area closer to the substrate is smaller than the masking of the upper layer. 7) Masking is performed on the substrate, A masking method used to fabricate a structure having a truncated cone shape by etching, in which masking is performed so that a narrow angle of etching can be performed as the etching depth increases. A masking method for microfabrication of a structure characterized by having a layer structure and a masking area closer to the substrate than the masking of the upper layer 8) The masking material was selected from metal, organic matter, glass and ceramics A masking method for microfabrication of a structure according to the above 6 or 7, characterized in that the material is a material. It consists of two or more kinds of materials with different etching rates, which are laminated on the substrate, and using the difference in etching rate between the upper layer and the lower layer of the mask, the masking areas of the upper layer and the lower layer are made different. 10) The masking method for microfabrication of a structure according to any one of 6 to 10 above, wherein the substrate masked by dry etching is etched to form minute convex portions on the substrate. 9 microfabrication masking method 11) substrate structure according to any one of diamond, metal, silicon, GaAs, AlN, GaN, made from a compound such as LaB _6, a sharp structure of these materials The method for masking a microfabrication of a diamond structure according to any one of the above 1 to 10, characterized in that is prepared.

According to the present invention, the shape of a structure or truncated cone having a sharpened tip on a substrate such as a compound of metal, silicon, GaAs, AlN, GaN, LaB ₆ or the like can be obtained by a relatively simple operation. It is possible to form the provided structure, and it has an excellent effect that a fine structure having a shape depending on the masking shape can be formed on the substrate with high accuracy.

In the present invention, multiple layers of masking are first performed on a substrate made of a compound such as diamond, metal, silicon, GaAs, AlN, GaN, LaB ₆ or the like. As the masking material, a material selected from metals, organic substances, glass, and ceramics can be used. The multi-layer masking material is preferably a material having a significantly different etching rate or one of which is not etched at all and the other is a material that can be partially dissolved and removed with acid or alkali relatively easily.
Which material is the substrate side, that is, the lower layer or the upper layer depends on the shape of the protrusion formed by etching on a compound such as diamond, metal, silicon, GaAs, AlN, GaN, LaB ₆ or the like. decide.

When a sharp structure such as diamond, metal, silicon, GaAs, AlN, GaN, LaB ₆ or the like is produced by etching, the masking is made into a multi-layer structure. By the etching method, the masking area closer to the substrate is made smaller than the masking of the upper layer. Such masking is shown in FIGS. 1a-b.
When etching is performed using such multi-layer masking, the masking structure is reflected in the etching, and the etching is performed at an angle that becomes wider as the etching depth becomes deeper. Therefore, the uneven shape on the substrate after etching is as shown in FIG. 1c, and a structure with high sharpness is obtained.
For etching the substrate, physical etching methods such as reactive ion etching, ion beam etching, electron cyclotron resonance etching, inductively coupled plasma etching, or chemical / physical etching methods can be used.

When a structure having a truncated cone shape is produced by etching, the masking has a multi-layer structure, and the masking area closer to the substrate than the upper layer masking by, for example, a chemical etching method. To be larger.
As a result, as the etching depth becomes deeper, etching is performed at a narrow angle, and as a result, a diamond structure having a truncated cone shape is formed. For the etching of the diamond substrate, a physical etching method similar to the above may be used.

In the present invention, the selection of a masking material is particularly important. That is, once, as shown in FIG. 1-a, a structure in which two or more materials having different chemical etching rates are simply laminated is formed, and then one masking material is partially removed by chemical etching. . Accordingly, the masking areas of the upper layer and the lower layer are made different by utilizing the etching rate difference between the upper layer and the lower layer of the masking.
When the area of the masking upper layer is large, the etching material (particles) flying from the outside enters even at an inclined angle, but such a random etching factor can be obtained by applying a bias to the substrate. It can be made small so that it can be ignored. Therefore, at the initial stage of etching, the substrate is etched in a substantially cylindrical shape through a relatively narrow gap in the upper layer mask shown in FIG.

However, as the etching progresses, the upper layer mask is etched and depleted simultaneously by the etching material (particles) in both the vertical and horizontal directions. Therefore, the mushroom-like shape shown in FIG. 1 (b) gradually becomes an elongated rod shape. That is, the area of the mask range is reduced. Therefore, during this time, the range of etching of the substrate gradually increases.
Although it is possible to make various shapes by controlling the mask design and etching, for example, as shown in FIG. Etching can be performed so that the fine protrusions thus formed remain on the diamond substrate.
For this purpose, as described above, the two-layer mask is formed in a mushroom shape. By such a simple mask design, a sharp convex part can be formed on the diamond substrate.

The same applies to a two-layer mask in which the area of the upper layer of the masking is small and the area of the lower layer is large. Etching material (particles) flying from the outside and entering also enters at an inclined angle, but by applying a bias to the substrate in the same manner, such a random etching factor can be made small so that it can be ignored, It can be etched almost vertically. Therefore, at the initial stage of etching, the substrate is etched in a substantially cylindrical shape through a relatively narrow gap in the lower layer mask shown in FIG.

However, as the etching progresses, the lower layer mask is etched and depleted by the etching material (particles) both in the vertical direction and in the horizontal direction. Therefore, the concentric circular combination trapezoid (cross-sectional convex shape) shown in FIG. 2 (b) gradually becomes an elongated rod shape. That is, the area of the mask range is reduced. Therefore, during this time, the range of etching of the substrate gradually increases.
In this case as well, as described above, various shapes can be formed by controlling the mask design and etching. As an example, etching can be performed so that the mask is finally almost eliminated by etching, and at the same time, as shown in FIG. it can.

For this purpose, a concentric combination trapezoidal (convex cross section) two-layer mask is formed. By such a simple mask design, a sharp convex part can be formed on the diamond substrate.
The above two examples show examples in which a sharp convex part is formed on a diamond substrate, but it has been sharpened by controlling the masking interval and the multilayer structure and shape. The structure of the diamond protrusion or the truncated cone can be arbitrarily selected. This is one of the major features of the present invention, and the diamond protrusion can be arbitrarily changed by a simple masking structure.

As described above, the sharpened diamond can be used as a diamond member for an electron-emitting device, for example, a member for a field emission display or a field emission microscope.
Further, in this case, an excellent feature is that a contact can be formed also on the upper end of the diamond. In the case of a structure such as a metal, silicon, GaAs, AlN, GaN, LaB ₆ or the like, it can be used as an emitter material.
As described above, the method of the present invention uses multiple layers of masking and devise the masking structure, so that diamond, metal, silicon, GaAs, AlN, GaN, LaB _{6 and the} like can be formed on the substrate with a relatively simple operation. This compound has an excellent feature that it can be finely controlled in an arbitrary shape.

Next, an actually manufactured example will be described. Note that this embodiment is described for ease of understanding, and the present invention is not limited to this embodiment. That is, all modifications, other embodiments, and other examples based on the technical idea of the present invention are included in the present invention.

(Example 1)
On the diamond substrate 1, as shown in FIG. 1A, a circular multilayer masking having a diameter of 1.0 μm was applied by a general photolithography technique. The first layer is aluminum 3 having a thickness of 0.2 μm, and the second layer is gold 2 having a thickness of 0.2 μm.
As shown in FIG. 1B, the aluminum 3 was partially dissolved and removed with an alkaline etching solution. As a result, the masking area of the lower layer (0.1 μm diameter) was reduced smaller than the masking area of the upper layer.
Next, the diamond substrate 1 was etched by performing plasma etching. As a result, after etching, as shown in FIG. 1C, a diamond microstructure having an average diameter of about 1 μm at the bottom surface provided with a sharpened tip was obtained.

(Example 2)
As shown in FIG. 2A, a circular multilayer masking having a diameter of 1.0 μm was applied on the diamond substrate 1 by a general photolithography technique. The first layer is silicon dioxide (SiO ₂ ) 4 having a thickness of 0.2 μm, and the second layer is aluminum 3 having a thickness of 0.2 μm.
As shown in FIG. 2 (b), the aluminum 3 was partially dissolved and removed with an alkaline etching solution. As a result, the masking area (0.1 μm diameter) of the upper layer was reduced to be smaller than the masking area of the lower layer.
Next, the diamond substrate 1 was etched by performing plasma etching. As a result, after the etching, as shown in FIG. 2C, a diamond microstructure having an average diameter of the bottom surface having a sharpened tip was about 1 μm was obtained.

The present invention has a feature that the application range as a diamond member for an electron-emitting device can be greatly improved, and is useful as a member for a field emission display or a field emission microscope.

A multi-layer mask (a) is formed on a diamond substrate, then the underlying mask is chemically etched from the side to reduce the area (b), and sharpened by etching using this mask. It is a conceptual explanatory drawing of the process which manufactures the diamond fine structure (c) with the turned tip part. Sharpening by forming a multi-layer mask (a) on a diamond substrate and then reducing the area by chemically etching the upper mask from the side (b) and etching using this mask It is a conceptual explanatory drawing of the process which manufactures the diamond fine structure (c) with the turned tip part.

Explanation of symbols

1 Diamond substrate 2 Gold 3 Aluminum 4 Silicon dioxide

Claims (11)

  When making a sharp structure by etching on the substrate and etching, the masking has a multi-layer structure, and etching is performed by reducing the masking area closer to the substrate compared to the upper layer masking. A fine processing method of a structure having high sharpness, characterized by performing etching at an angle that becomes wider as the depth becomes deeper.   When a mask is formed on a substrate and a structure with a truncated cone shape is produced by etching, the masking is made into a multi-layer structure, and the masking area closer to the substrate is made larger than the masking of the upper layer. A fine processing method for a structure having a truncated cone shape, characterized in that etching is performed at a narrow angle as the etching depth increases.   3. The method for microfabricating a structure according to claim 1, wherein the masking material is a material selected from metal, organic matter, glass and ceramics.   The masking material consists of two or more materials with different etching rates, which are stacked on the diamond substrate, and the masking areas of the upper and lower layers are made different by using the difference in etching rate between the upper and lower layers of the masking. The method for microfabrication of a structure according to any one of claims 1 to 3, wherein:   5. The microfabrication method for a structure according to claim 1, wherein the substrate is etched by dry etching to form minute convex portions.   A masking method used for masking a substrate and producing a sharp structure by etching. The masking is performed so that a wide range of angles can be etched as the etching depth increases. A masking method for microfabrication of a structure, which has a layered structure and has a smaller masking area closer to the substrate than the masking of the upper layer.   A masking method used for manufacturing a structure having a truncated cone shape by performing masking on a substrate and performing etching at a narrow angle as the etching depth increases. A masking method for microfabrication of a structure, characterized in that the masking has a multilayer structure, and the masking area closer to the substrate is larger than the masking of the upper layer.   The masking method for microfabrication of a structure according to claim 6 or 7, wherein the masking material is a material selected from metal, organic matter, glass and ceramics.   The masking material consists of two or more materials with different etching rates, which are stacked on the diamond substrate, and the masking areas of the upper and lower layers are made different by using the difference in etching rate between the upper and lower layers of the masking. The masking method for fine processing of a structure according to any one of claims 6 to 8, wherein the masking method is used.   The masking method for microfabrication of a structure according to any one of claims 6 to 9, wherein the substrate masked by dry etching is etched to form minute convex portions on the substrate. The substrate is made of a compound such as diamond, metal, silicon, GaAs, AlN, GaN, LaB _{6 and the} like, and a structure of these materials having sharpness is produced. Masking method for microfabrication of diamond structures.