JP3401565B2 - Fine patterning method - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention does not require complicated masking work which has been conventionally performed when patterning single crystal silicon, and can change the patterning mode depending on the concentration of an etching solution. And a fine patterning method.

[0002]

2. Description of the Related Art Conventionally, in the manufacture of semiconductors, a photoresist that is sensitive to light is applied to the surface of a thinly cut single crystal silicon wafer, and then the surface is covered with an exposure mask pattern and exposed to deep ultraviolet rays for exposure. By developing this, the pattern of the mask is transferred to the photoresist. Next, this is oxidized, and the resist pattern thus formed is subjected to etching treatment to form a pattern of an actual circuit. Such a technique is widely used not only in semiconductor manufacturing but also in, for example, molding of a minute member made of single crystal silicon.

[0003]

As described above, when finely processing single crystal silicon by etching, it is necessary to perform a photoresist adhesion process, a mask pattern transfer operation by irradiation with deep ultraviolet rays, an oxidation process, etc., which is complicated. Since the process needs to be performed many times, there is a problem that it takes a lot of time and labor.

Further, in order to change the existing pattern, it is necessary to remake the exposure mask, and there is a problem that it is not suitable for manufacturing a fine structure which requires a degree of freedom in trial manufacture.

Furthermore, when forming concaves and convexes of various shapes on single crystal silicon, there is no choice but to form the masked portions as convexes, so that the method of forming the concaves and convexes is limited. There was also a problem.

Therefore, according to the present invention, when finely processing single crystal silicon by etching, it is possible to easily form and change an etching mask pattern in a short time without the need for photoresist treatment, far ultraviolet ray irradiation work, oxidation treatment and the like. In addition to providing a method for performing patterning with a high degree of freedom, it is possible to form a masked portion as a convex portion or this portion as a concave portion when processing single crystal silicon by etching. It is an object of the present invention to provide a processing method according to the above.

[0007]

In order to solve the above-mentioned problems, the present invention relates to a first aspect of the invention, in which the surface of a single crystal silicon material is subjected to micromachining in a predetermined shape and the material is etched by an etching solution. In the fine patterning method for forming a fine pattern having a predetermined shape by performing the above, by arbitrarily selecting the concentration of the etching solution, the masking effect or the etching accelerating effect can be selected for the finely machined portion to be a fine pattern. This is a fine patterning method characterized by performing patterning.

The invention according to claim 2 provides the fine patterning method according to claim 1, wherein the fine machining is performed by a mechanism of a friction force microscope.

The invention according to claim 3 provides the fine patterning method according to claim 1, wherein an aqueous solution of potassium hydroxide is used as the etching solution.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A frictional force microscope (FF
M) or a microfabrication technique using a scanning probe microscope (SPM) technique such as an atomic force microscope (AFM) has been studied. For example, as a micro processing machine utilizing the principle of a friction force microscope, as shown in FIG. 1, a high-rigidity processing cantilever 4 is used instead of a flexible cantilever used in a conventional friction force microscope, and a laser diode 1 is used. The laser light of the lens 2
The diamond abrasive grains 5 in contact with the surface of the material 3 are radiated to the back surface of the tip of the processing cantilever 4 provided at the tip through the above, and the reflected light is received by the four-division photodetector 6.

The received light signal is a signal obtained by detecting the state of the machining cantilever 4 by an optical lever method and represents the state of bending and twisting of the machining cantilever 4, so that signal is input to the feedback control device 8. The current deflection and twist of the processing cantilever is calculated, and this is compared with a preset value to calculate the error signal as a tube type P
It is outputted to the ZT scanner 7 so that the material 3 can be processed in a predetermined shape while moving in the X, Y and Z directions and maintaining a predetermined cutting depth.

As shown in the enlarged view of FIG. 1 (b), the processing cantilever 4 has a diamond abrasive grain 5 having a sharp tip as shown in the enlarged view of FIG. 1 (c) at the tip of the lever 10. It is attached, and this cantilever has high rigidity as described above. By using such a tool, the surface of the material is rubbed, and fine cutting can be performed with a cut on the order of nanometers.

In the present invention, such a micro processing machine is used to perform fine cutting with diamond abrasive grains along a predetermined masking shape. At this time, crystallinity disorder and residual stress are present on the surface after cutting, and a work-affected layer is formed. It was discovered that it has a masking effect on anisotropic etching using potassium oxide.

Utilizing this characteristic, in the present invention, as shown in the outline of the processing method in FIG. 2 (a), for example, a square recess 12 in this embodiment is formed on the surface of the material 3 in the air, and the cantilever 4 is formed. The diamond abrasive grains 5 of No. 3 are used, and the material 3 after such processing is put into an aqueous potassium hydroxide (KOH) solution 14 in a container 13 as shown in FIG. And stir to etch. Thereafter, this is washed with running water as in the conventional etching treatment and dried.

FIG. 4A shows an AFM observation image as a result of actually performing ultrafine processing by such an FFM mechanism.
This is the processing area 15μm × 15μm, vertical load 1184
A concave portion having a μN, a processing speed of 120 μm / s, and a depth of about 34 nm is formed, and its sectional view is shown in FIG. After such processing, an AFM observation image of a result obtained by performing an etching treatment for 20 minutes with a 15 wt% KOH aqueous solution is shown in FIG. 5 (a), and its sectional view is shown in FIG. 5 (b). As is apparent from the above, the microfabrication causes the processed portion to have a masking action, and the periphery thereof is selectively etched. For example, as shown in FIG. 3A, when the KOH aqueous solution concentration is 10 wt%, The relationship between the etching treatment time and the residual height is clear that the residual height increases as the treatment time increases. This means that the processed portion has a work-affected layer that has sufficient corrosion resistance to the KOH aqueous solution. It shows that it has been formed.

On the other hand, here, K as an etching treatment liquid is used.
When the concentration of the OH aqueous solution was changed, the relationship between the change in the concentration and the residual height became as shown in FIG. 3 (b). This graph shows the relationship between various concentrations and residual heights when the etching treatment time is set to 20 minutes. After forming the recesses by the above-described fine processing method, KOH for etching is used.
The results are obtained by changing the concentration of the aqueous solution. As a result, when the concentration is gradually increased from 0%, the finely machined portion exhibits a masking effect in the low concentration range. Therefore, when the etching is performed for 20 minutes, the residual height is 0 at the micromachined portion at the beginning, so the depth of the recess is reduced by etching the peripheral portion, that is, a substantially flat surface. The state that becomes a state also occurs.

Since the etching rate increases as the concentration is further increased, the residual height gradually increases when the etching time is 20 minutes. In the illustrated embodiment, the highest concentration is obtained when the concentration of the KOH aqueous solution is about 15 wt%. Becomes However, if the concentration is further increased, on the contrary, the etching action of the finely machined portion becomes relatively stronger than that of other portions.
Therefore, as shown in the graph, the concentration is about 20 wt.
%, It becomes almost flat in the etching treatment time of 20 minutes. When the concentration is higher, the finely processed portion is etched more than the non-processed portion, and this portion becomes a recess. That is, in a low concentration condition, a masking effect is obtained,
The etching promoting effect is exhibited under the condition of high concentration.

It is clear from the AFM observation images shown in FIGS. 6 and 7 that the etching action of the KOH aqueous solution differs depending on the fine processing. That is, in the case of a 5 wt% KOH aqueous solution, the processed portion after performing the etching process for 20 minutes has a residual height of 130 n as shown in FIG.
In the case of 15 wt%, the residual height is 260 nm as shown in FIG. 6 (b). On the other hand, 20 wt%
7 (a), the residual height is 0 nm, that is, it becomes almost flat, and in the case of 35 wt, on the contrary, the finely processed portion is relatively more etched, and the recess depth is about It is 150 nm.

By subjecting the single crystal silicon to micromachining as described above, in addition to simple projections and depressions, four pillars as shown in FIG. 8A can be provided in a row. That is, in this example, the height is about 540 nm, and four 5 μm × 5 μm prisms are formed adjacent to each other. Note that FIG. 7B is a cross-sectional view of the portion AA in FIG.

As still another processing example, for example, as shown in FIG. 9 (a), streaky columnar bodies may be provided in a row. That is, in this example, the height is about 540 nm and the length is about 5 μ.
Three m-shaped columnar bodies are formed adjacent to each other. It should be noted that FIG. 7B is a sectional view of a portion B-B in FIG.

In the above embodiment, an example in which KOH is used as the etching solution has been shown, but other various etching solutions conventionally used can be used. Further, in the above-mentioned embodiment, the concave and convex portions are formed on silicon, but various shapes can be formed by further advancing the concave portions to form through holes or cut portions. .

[0022]

INDUSTRIAL APPLICABILITY As described above, the present invention provides a fine patterning method for forming a fine pattern having a predetermined shape by subjecting the surface of a single crystal silicon material to micromachining of a predetermined shape and etching the material with an etching solution. Since the fine patterning method is characterized in that either the fine machining portion or the portion other than the fine machining portion is selected as the masking action portion by arbitrarily selecting the concentration of the etching solution, crystalline silicon is used. Microfabrication by etching does not require photoresist treatment, far-ultraviolet ray irradiation work, oxidation treatment, etc., and the etching mask pattern can be easily formed and changed in a short time. Can be done. Also, when processing single crystal silicon by etching, by arbitrarily selecting the concentration of the etching solution, the microfabrication part develops a masking effect under low concentration conditions and an etching promotion effect under high concentration conditions. Therefore, it is possible to easily perform microfabrication in various modes by simply changing the concentration of the solution, such as making this a convex portion for the same micromachined portion or making this portion a concave portion. it can.

Further, in the case where the fine machining is performed by a mechanism of a friction force microscope, an extremely accurate etching mask pattern can be easily formed.

Further, in the case where the potassium hydroxide aqueous solution is used as the etching solution, a predetermined shape can be stably formed in the single crystal material by etching.

[Brief description of drawings]

FIG. 1 is a perspective view showing an embodiment using a friction force microscope for carrying out a fine patterning method according to the present invention, in which (a) is an overall perspective view and (b) is an enlarged view of a cantilever portion. A perspective view, (c) is a perspective view of the diamond abrasive grains at the tip of the cantilever.

FIG. 2 is a diagram showing a process for carrying out a fine patterning method according to the present invention, (a) is a perspective view schematically showing a portion to be subjected to fine machining, and (b) is an etching process. It is a sectional view showing typically.

FIG. 3 shows an experimental result for clarifying the action of the etching solution in the present invention, and (a) is a graph showing the elapsed time and the residual height of the micromachined portion when the concentration of the etching solution is constant. , (B) are graphs showing the concentration of the etching liquid and the residual height of the finely machined portion when the etching time is constant.

FIG. 4 shows an example in which fine concave portions are formed in a single crystal silicon material by using a mechanism of a frictional force microscope.
It is an example of the image which carried out M observation, (b) is the sectional view.

FIG. 5 shows an example in which the single crystal silicon material in which the fine recesses are formed is subjected to an etching treatment with a 15 wt% KOH aqueous solution for 20 minutes, (a) is an example of an image subjected to AFM observation, and (b) is ) Is a sectional view thereof.

FIG. 6 is an example of an AFM image when the single crystal silicon material having the fine recesses formed therein is etched with a KOH aqueous solution having various concentrations for 20 minutes, and (a) shows a case where the concentration is 5 wt%. , (B) are examples at 15 wt%.

FIG. 7 is an example of AFM images of various densities,
(A) is an example when it is 20 wt%, and (b) is an example when it is 35 wt%.

FIG. 8 shows a state when a fine structure of another embodiment is formed according to the present invention, (a) shows an example of the AFM image,
(B) is the AA partial sectional view.

9A and 9B show a state in which a fine structure of still another embodiment is formed according to the present invention, FIG. 9A shows an example of an AFM image thereof, and FIG. 9B is a sectional view taken along line BB thereof.

[Explanation of symbols]

1 laser diode 3 materials 4 Processing cantilever 5 diamond abrasive 6 4-division photo detector 7 tube PZT scanner 8 Feedback control device

Claims (3)

(57) [Claims] 1. A fine patterning method for forming a fine pattern having a predetermined shape by subjecting a surface of a single crystal silicon material to micromachining of the predetermined shape, and etching the material with an etching solution, wherein the concentration of the etching solution is arbitrarily set. A fine patterning method characterized by performing fine patterning by arbitrarily selecting one of a masking effect and an etching promoting effect on the micromachined portion by selecting. 2. The fine patterning method according to claim 1, wherein the fine machining is performed by a mechanism of a friction force microscope. 3. The fine patterning method according to claim 1, wherein an aqueous solution of potassium hydroxide is used as the etching solution.