JPH10135180A - Rinsing solution for drying treatment, method for drying treatment using the solution, and manufacture of small structure using the method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make special facilities unnecessary by preventing breakage of samples and to make drying treatment simpler by using a rinsing solution for drying treatment which does not vaporize abruptly from a solid. SOLUTION: A rinsing solution for drying treatment which does not vaporizes abruptly from a solid state is used. Materials which meets this condition includes an organic compound having a vapor pressure of 0.05-8mmHg at 20 deg.C. The other requirements are such that melting point or solidifying point of the material must not be too much higher than a room temperature, but appropriately higher than the room temperature, and the material appropriately sublimates under a reduced-pressure condition. The material which meets all these requirements must be such a material that can maintain state of solid at a room temperature and gradually sublimate under a room-temperature atmospheric-pressure condition, but can relatively easily dissolve in liquids. When the safety of heating treatment is taken into consideration, p- dichlorobenzene having a melting point of about 40 deg.C is preferable.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rinsing liquid for a drying treatment used for producing an article requiring a drying treatment, and a method for producing an article using the rinsing liquid. In particular, the present invention relates to an etching method by wet etching used in microfabrication technology related to semiconductor manufacturing and a method of manufacturing a microstructure by micromachining using the same, particularly for efficiently forming a microstructure having voids. And a method for producing the same.

[0002]

[Prior art]

[Micromachining Technology] In the microfabrication technology currently used in the manufacture of semiconductors, it is possible to form a very fine pattern having a size of submicron.

[0003] With the progress of such fine processing technology, a so-called micromachining technology using the microprocessing technology has recently attracted attention. Here, the micromachining technology is a micromachining technology for manufacturing a microstructure having a three-dimensional structure called a micromachine. And
This micromachining technology is considered to be an important core technology for realizing the manufacture of a new high-performance device that exceeds the limits of conventional machining. For micromachining technology, see Micromachine Development Technology Notebook (Masao Fuji et al., 3 authors, published on March 1, 1991, Shujunsha), Micromachining and Micro Mechatronics (Masashi Esashi et al., 3 June 1992) (Published on March 20, Baifukan) has a detailed description.

One of the important techniques in the micromachining technique is an etching method called sacrificial layer etching.

[Sacrificial layer etching] The sacrificial layer etching will be described below.

The sacrifice layer etching is an etching method for creating a void portion in a three-dimensional structure. Therefore, in the sacrifice layer etching, a layer to be a void portion is formed on the substrate in advance, and a part or the whole of the layer is etched and removed again. In this method, since a layer serving as a void portion is selectively removed, the layer is called a sacrificial layer.

However, the sacrificial layer may be formed on the substrate or may be formed on a part of the substrate. Also,
As described above, the sacrificial layer may be partially removed or entirely removed. In consideration of this point, a portion selectively removed is hereinafter referred to as a sacrificial layer portion.

Therefore, in the sacrificial layer etching, a three-dimensional structure having voids is formed through the following operation steps.

(Step A-1) Formation of Sacrificial Layer Portion A layer having a desired shape different from the substrate is formed on the substrate or on a part of the substrate. A layer different from this substrate is a sacrificial layer. However, a layer different from the substrate means a layer in which at least one of the crystal structure and the composition of the substance constituting the layer is different from the substance constituting the substrate. In particular, when the composition is different, it also includes a substance formed by doping.

(Step A-2) Formation of a layer having a three-dimensional structure On the formed sacrificial layer portion, a layer having a desired shape and different from the sacrificial layer portion is formed. A layer different from the sacrificial layer portion is a layer having a three-dimensional structure. However, a layer different from the sacrificial layer portion means a layer having at least one of a crystal structure and a composition different from the sacrificial layer portion. Here, similarly to the above, when the composition is different, a substance formed by doping is also included.

(Step A-3) Removal of sacrificial layer portion The sacrificial layer portion formed below the layer having the three-dimensional structure is removed by etching.

However, the shape of the sacrificial layer portion and the layer forming the three-dimensional structure is formed by using the same patterning method as in the prior art.

By using such a sacrificial layer etching, a structure such as a suspension, a cantilever, which is partially supported in a state of being floated from the substrate, and a portion which rotates on the substrate, such as a gear or a motor, are included. You can create a structure.

Incidentally, in this sacrificial layer etching, wet etching is used in many cases. The reason will be described next.

In the sacrifice layer etching, the sacrifice layer portion needs to be selectively removed as compared with other portions. Therefore, a suitable etching method is one that can easily obtain etching selectivity.

[Etching Method Used in Sacrificial Layer Etching] Generally, there are wet etching and dry etching as etching methods. Of these two methods, the wet etching is more preferable than the etching method. It is known that the property can be easily obtained. For this reason, wet etching is often used in sacrificial layer etching.

The wet etching is a method in which an etching solution called an etchant is used and the layer is eroded and removed by utilizing the chemical reactivity of the solution. On the other hand, dry etching also utilizes the physical effect of causing gas atoms charged by discharge to collide with a layer. In other words, wet etching is easier to obtain etching selectivity than dry etching that also uses physical action in that only chemical reactivity is used.

[General working process of wet etching]
Here, a series of work steps generally performed as an etching process when performing wet etching will be described. Before and after the following etching process, there are a normal resist pattern forming step and a resist pattern peeling step, respectively.

(Step B-1) Etching Step A sample to be etched is immersed in an etchant to remove unnecessary portions.

(Step B-2) Cleaning Step The sample removed from the etchant is rinsed with water or the like to remove the attached etchant. This process is called a cleaning process rinse. The rinse stops the progress of etching.

The water used for the rinsing for cleaning is called a rinsing liquid for cleaning.

(Step B-3) Drying Step Subsequently, the rinsing liquid for cleaning treatment adhered to the sample in the cleaning step is removed. At this time, when the drying treatment is performed by removing the rinsing liquid for cleaning treatment as it is, the rinsing liquid for cleaning may be removed by using another substance different from the rinsing liquid for cleaning treatment as the rinsing liquid for drying treatment. And two types of drying treatment.

Here, when the rinsing liquid for drying treatment is used, it is necessary to replace the rinsing liquid for cleaning treatment adhering to the sample with the rinsing liquid for drying treatment. For this purpose, an operation of rinsing the sample after the cleaning step using a rinsing liquid for drying treatment is performed. Here, this processing is referred to as drying processing rinsing.

Depending on the physical compatibility between the rinsing liquid for cleaning and the rinsing liquid for drying, the rinsing liquid for cleaning may not be directly replaced with the rinsing liquid for drying. In such a case, the following intermediate replacement processing needs to be performed at the first stage of the drying process.

That is, before performing the drying rinsing on the sample after the cleaning step, the sample is rinsed with another substance that can be replaced with both the cleaning rinsing liquid and the drying rinsing liquid. By performing such a process, it is possible to replace the rinse solution for the drying process.

For example, when water is used as the rinsing liquid for the cleaning treatment and an organic compound that is insoluble or not water-soluble is used as the rinsing liquid for the drying treatment, the rinsing is performed using the organic compound used as the rinsing liquid for the drying treatment. Before the treatment, an intermediate substitution treatment may be performed using a water-soluble organic compound such as ethanol.

A series of working steps performed as the above-described wet etching are similarly performed in the case of sacrificial layer etching.

[Problems of Sacrificial Layer Etching Using Wet Etching] However, in the sacrifice layer etching using wet etching, the following phenomena occur frequently and have been problematic. The phenomenon is that in the above-mentioned drying step, when the rinsing liquid for cleaning treatment is dried,
The three-dimensional layer is stuck to the substrate and cannot be easily peeled off.

The drying method used in such a case was the same as the conventional method such as a spin drier, steam cleaning or evaporation. By the way, one of the causes of the occurrence of such a phenomenon is considered to be the influence of the surface tension of the rinsing liquid for cleaning treatment.

Due to the above problems, it has been extremely difficult to actually produce a microstructure by a conventional manufacturing method using a drying treatment method.

[Freeze-drying method] In order to avoid the above-mentioned problem, as a method of drying the rinse solution for washing treatment, a drying treatment method called freeze-drying method was used.

The freeze-drying method is a method in which, in order to dry an object, a substance attached to the object is solidified, and the substance is changed from a solid to a gas to remove the attached substance. It is.

The change of state from a solid to a gas is hereinafter referred to as vaporization from a solid.

[Drying treatment by freeze-drying of water] In the freeze-drying method conventionally used, the substance removed by the drying treatment was water used as a rinse liquid for washing treatment.

However, when water is subjected to a drying treatment by a freeze-drying method, there are mainly the following two problems.

(1-1) The volume change of water during coagulation is large.

Water expands in volume upon change of state to a solid, ie, solidification. Therefore, there is a risk that the microstructure is destroyed due to the volume change, and it is not expected that a stable yield is obtained in actual production.

(1-2) It is necessary to reduce the pressure while keeping the sample to be dried below 0 ° C.

Since the freeze-drying method utilizes vaporization from a solid, water must be kept in a solid state. For that purpose, it is necessary to use a special device capable of performing the decompression work while keeping the sample below 0 ° C. As a result, manufacturing costs increase.

For the above reasons, the method of drying water by freeze-drying cannot be put to practical use in actual production.

[Drying treatment of t-butyl alcohol by freeze-drying] As one means for solving such a problem, the following method has been proposed. Reported in 397. The method is to use t-butyl alcohol as a rinsing liquid for drying treatment separately from water which is a rinsing liquid for cleaning treatment.

When the above-mentioned water is used, freeze-drying has been carried out as it is after the washing treatment. On the other hand, when t-butyl alcohol is used, an operation of first performing a drying treatment rinsing using t-butyl alcohol is added as a drying step. That is, after the washing treatment with water, the sample is rinsed with t-butyl alcohol, and the water adhering to the sample is replaced with t-butyl alcohol. Thereafter, t-butyl alcohol is coagulated and dried by changing its state from a solid to a gas.

This method using t-butyl alcohol,
Handling in a solid state was slightly easier than in the above method using water. The reason is that the freezing point of t-butyl alcohol is 25.6 ° C., which is close to room temperature, so that it is no longer as difficult to maintain a solid state as in water. Therefore, at first glance, it is considered that t-butyl alcohol is suitable as the rinsing liquid for drying treatment.

However, this method using t-butyl alcohol has the following five main problems.

(2-1) Destruction of the microstructure is caused by vaporization from the solid.

In general, changes in the state of a substance include temperature, pressure,
Or, it is not easy to control the speed because it depends on the amount of the substance.

In the case of t-butyl alcohol, even if the temperature and pressure are strictly controlled, rapid solidification in a vacuum may occur during freeze-drying depending on the amount of liquid. Here, rapid vaporization from a solid means that only a certain portion of the t-butyl alcohol layer attached around the sample locally changes to vaporization. For this reason, a phenomenon occurs in which solid t-butyl alcohol in a non-vaporized portion is separated from the solid, and moves violently on the sample. For this reason, the microstructure may be destroyed, and as a result, the production yield may be reduced.

From the viewpoint of actual production, this problem (2-1), which causes a decrease in yield, can be said to be the most serious problem.

In addition, a more preferable solution will be described below as a problem of work or equipment.

First, since the freezing point of t-butyl alcohol is around room temperature, there are the following problems.

(2-2) It is necessary to strictly control the temperature and humidity of the working environment and the storage place.

When t-butyl alcohol is used, it is necessary to maintain the temperature of the working environment sufficiently lower than the freezing point, because if the working environment temperature is not sufficiently lower than the freezing point, it melts and becomes liquid. This is because there is a risk of becoming. This problem will be specifically described.

I) It is difficult to maintain a stable solid state.

In particular, in the summer, for example, in order to maintain a stable solid state, it is necessary to maintain the temperature of the working environment at a low temperature using a cooling device. For that purpose, facilities such as air conditioning are required, and the manufacturing cost is increased.

Ii) It is easily affected by freezing point depression.

Here, the freezing point drop will be described. The freezing point drop refers to a phenomenon in which the freezing point of the solvent drops as the solute dissolves in the solvent. The term freezing point depression is a general abbreviation of molar freezing point depression.

In the case of t-butyl alcohol, when the freezing point drops, the possibility of melting and becoming liquid is very high. The reason is that the freezing point is a value close to room temperature as described above.

For example, when a small amount of water or the like is mixed, the freezing point easily drops to room temperature or lower. In this case, t-butyl alcohol corresponds to a solvent that causes a freezing point drop in a solute in which water dissolves. In particular, water has the risk of being easily mixed in by condensation due to temperature changes,
It is necessary to strictly control the humidity of the working environment.

For the same reason, when storing the solution,
An environment in which temperature and humidity are strictly controlled is required.

Further, when simplification of the operation is considered, there is the following problem.

(2-3) A vacuum device is required when performing the drying process.

When t-butyl alcohol is used, the drying treatment must be performed under reduced pressure. Therefore, a vacuum device is required. In addition, as mentioned in (2-2) above, the temperature of the working environment must be kept below the freezing point of t-butyl alcohol. Otherwise, it is necessary to provide a cooling mechanism in the sample holding section of the vacuum apparatus.

As can be seen from the above two points (2-2) and (2-3), the problem of work or equipment did not lead to drastic reduction in cost or simplification of work.

As described above, the freeze-drying method using t-butyl alcohol is not particularly superior to that using conventional water. For these reasons, the drying treatment using t-butyl alcohol has not been a practical and effective method.

[0065]

In view of the above-mentioned problems of the prior art, the required drying treatment method must first be a drying treatment method with a high yield without destroying the sample. In addition, from the viewpoint of practicality in manufacturing, it is preferable that the drying method is simple and does not require special equipment. It is preferable that the yield of microfabrication be improved by using such a drying treatment method.

Therefore, the problems to be solved by the present invention are the following six points.

(Problem 1) An object of the present invention is to provide a rinsing liquid for drying treatment that does not cause rapid evaporation of solids.

(Problem 2) An object of the present invention is to provide a drying treatment method which uses the above-mentioned rinsing liquid for drying treatment and has a good yield so as not to destroy the sample.

(Problem 3) The drying treatment method described above,
Also, to provide a simple and low-cost drying method that does not require complicated temperature and humidity management and does not particularly require devices and equipment such as a cooling device.

(Problem 4) The drying method described above,
Further, it is an object of the present invention to provide a simple and low-cost drying treatment method which does not particularly require a vacuum device or the like for the drying treatment.

(Problem 5) To provide an etching method capable of performing fine processing with good yield by utilizing the above-mentioned drying treatment method.

(Problem 6) To provide a method for manufacturing a microstructure which is inexpensive and has a good yield by using the above-mentioned etching method.

[0073]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems of the prior art, and uses a rinsing liquid for drying treatment which does not cause rapid evaporation of solids. Accordingly, the present invention provides a simple and low-cost drying method with a good yield, an etching method using the drying method, and a method for manufacturing a microstructure using the etching method.

That is, the present invention provides a rinsing liquid for drying treatment used for performing a drying treatment, which is solid at 20 ° C. and has a vapor pressure of 0.05 m at that temperature.
A rinsing liquid for drying treatment, which is an organic compound having a mHg of 8 mmHg or more.

When the melting point of the organic compound is 40.degree.
It is a rinsing liquid for drying treatment, wherein the rinsing liquid has a temperature of not more than ℃.

A rinsing liquid for drying treatment, wherein the organic compound has sublimability under normal temperature and normal pressure.

The rinsing solution for drying treatment, wherein the organic compound is p-toluidine.

The rinsing solution for drying treatment, wherein the organic compound is tetrahydrofurfuryl alcohol.

A rinsing solution for drying treatment, wherein the organic compound is p-dichlorobenzene.

A rinsing liquid for drying treatment, which is used in the drying step after the wet etching step or after the cleaning step performed continuously to the wet etching step.

In a method for drying an object, the object is dried by using the above-described rinsing liquid for drying treatment, coagulating the rinsing liquid for drying treatment, and then evaporating the object in a solid state. It is a drying treatment method characterized by the above-mentioned.

A drying method in a drying step after a wet etching step or after a cleaning step performed continuously to the wet etching step, characterized by drying using the above-mentioned drying method. It is.

An etching method by wet etching, comprising a drying step using the above-mentioned drying method after a wet etching step or after a cleaning step performed continuously to the wet etching step. is there.

The etching method is characterized in that the etching method is a sacrifice layer etching for etching a sacrifice layer portion to be selectively removed.

[0085] In the etching method, the sacrificial layer portion may be a layer used for forming a microstructure having voids.

The sacrifice layer portion may be a part or all of a layer formed on a substrate different from the substrate, or a layer different from the substrate formed on a part of the substrate. This is an etching method.

[0087] In the etching method, a layer different from the substrate may be formed of a material having a different crystal structure from a material forming the substrate.

[0088] In the etching method, a layer different from the substrate may be formed of a material having a different composition from a material forming the substrate.

A method for producing a microstructure having voids, the method comprising using the etching method described above.

The method for manufacturing a microstructure according to the present invention is characterized in that the microstructure has a structure in which the microstructure is supported partially in a state of floating from the substrate.

The manufacturing method is characterized in that the microstructure has a structure including a portion rotating on a substrate.

[0092]

Embodiments of the present invention will be described below.

[Substances Usable in Rinsing Solution for Drying Process] Results of detailed examination of various problems that occurred in the conventional drying process, that is, the conventional freeze-drying process using water or t-butyl alcohol. The conditions that should be satisfied by the substance that can be used as the rinsing liquid for drying treatment were as follows.

(Condition A) Moderate vaporization from solids Here, “moderate” refers to rapid vaporization of solids as in the case of using t-butyl alcohol, and It means that a part does not move around the sample violently.

If this condition is satisfied, the risk of sticking the microstructure to the substrate or destroying the microstructure during the drying process can be excluded.

A substance satisfying this condition is 20 ° C.
At 20 ° C and a vapor pressure of 0.0
There are organic compounds of 5 mmHg to 8 mmHg. The main ones are summarized in Table 1 below. However, the notation of the unit of vapor pressure used in Table 1 mmHg / 20 ℃ is 20
It means that the vapor pressure at ° C is expressed in mmHg. The sublimability with or without sublimability means sublimability under normal temperature and normal pressure, ○ indicates sublimability, and X indicates no sublimability.

[0097]

[Table 1]

By subjecting the substance shown in Table 1 to a freeze-drying process using a rinse solution for the drying process, at least the problem of destruction of the microstructure during the drying process can be solved. That is, the drying treatment can be performed without destroying the microstructure.

As shown in Table 1, it is solid at 20 ° C. and has a vapor pressure of 0.05 mm at 20 ° C.
For organic compounds having an Hg of 8 mmHg or more, a eutectic mixture containing at least one of them can be used as a rinsing liquid for drying treatment. Here, the eutectic mixture refers to a mixture of two or more types of crystals in which each component is simultaneously precipitated from a solution, in other words, each component is simultaneously melted.

Further, considering the practical difficulties,
The condition that is preferably satisfied is the following (Condition B).

(Condition B) The melting point (or freezing point) should be moderately higher than room temperature and not too high. First, if the substance has a moderately higher freezing point than room temperature, it can be solidified at room temperature without using a cooling device. Can be maintained. Also, the effect of freezing point depression can be neglected. In particular, if the freezing point is 40 ° C. or higher, it can be used without problems at normal working environment temperatures.

Further, as long as the substance has a melting point not too high, even if it is solid at room temperature, it can be melted by a simple heating operation and used as a rinsing liquid. In particular, if the melting point is 100 ° C. or less, the heating operation can be easily performed without special equipment.

If the substance satisfies the above (condition B),
No special control of the temperature and humidity of the working environment or storage area, no cooling device for coagulation or no heating device for melting is required.

By the way, if the substance has a melting point of 40 ° C. or more and 100 ° C. or less, it is clear that the above (condition B) is satisfied. In Table 1, naphthalene, p-toluidine, p-dichlorobenzene are shown. , Tetrahydrofurfuryl alcohol. Since all of these have a melting point of 40 ° C. or higher, they can be solidified by, for example, spontaneous cooling by standing, and even if the freezing point drops, it hardly drops below room temperature. All of these have melting points
Since the temperature is 90 ° C or less, a water bath can be used for heating, and there is little danger. In particular, p-toluidine and p-dichlorobenzene melt easily because their melting points are 60 ° C. or less.

In addition to the above two points, more desirably, the following (condition C) is satisfied.

(Condition C) Moderate sublimation in a non-reduced pressure state In other words, if this condition is satisfied, the drying process should be performed by leaving the device in an appropriately ventilated place for several hours without using a vacuum device. Can be.

Here, it is clear that a substance having sublimability under normal temperature and normal pressure satisfies the above (condition C). In Table 1, naphthalene, camphor, p-
Dichlorobenzene corresponds to this.

Considering the simplification of the intermediate substitution treatment in the drying step, (condition D-1) is soluble in water or (condition D-2) is soluble in a water-soluble organic compound such as ethanol. This is a desirable additional condition.

All the substances shown in Table 1 are soluble in ethanol and satisfy (condition D-2). Further, tetrahydrofurfuryl alcohol and 1-methoxy-2-propanol are soluble in water, and also satisfy (condition D-1). Note that p-toluidine is slightly soluble in water.

[Substances preferably used as rinsing liquid for drying] Substances particularly preferable to be used as rinsing liquid for drying are substances satisfying all of the above-mentioned conditions (conditions A) to (conditions C). . By using such a substance as a rinsing liquid for drying treatment, all of the above problems are solved.

By the way, the above conditions (condition A) to (condition
The substance satisfying all of C) is a substance that gently sublimates under normal temperature and normal pressure and is a solid at normal temperature, but relatively easily melts and becomes a liquid. Among these are naphthalene and p-dichlorobenzene.

However, considering the safety during the heat treatment, p-dichlorobenzene having a melting point closer to 40 ° C. is more preferable.

[Other Substances Similar to p-Dichlorobenzene] Other substances having properties similar to those of p-dichlorobenzene include camphor besides naphthalene. Camphor cannot be heated using a water bath because its melting point is not as low as p-dichlorobenzene, but heating for melting is not so difficult and it can be relatively easily made into a liquid. Moreover, since it has sublimability under normal temperature and normal pressure, there is an advantage that drying treatment is easy.

Therefore, all of the above-mentioned problems can also be solved by performing a freeze-drying process using camphor as a rinse rinse solution.

[Method 1 of Manufacturing Microstructure by Sacrificial Layer Etching When Using p-Dichlorobenzene]
An operation procedure relating to a method for manufacturing a microstructure by sacrificial layer etching when p-dichlorobenzene, which is particularly preferable as a rinsing liquid for drying treatment, is used will be described.

(Step B-1) Etching Step i) Sacrificial layer etching is performed. That is, the sample is immersed in an etchant such as an acid or an alkali to remove a layer that becomes a void portion of the microstructure.

(Step B-2) Cleaning Step ii) After the completion of the etching, a cleaning treatment rinse using water is continuously performed. That is, the etchant adhering to the sample is replaced with water which is a rinsing liquid for cleaning treatment.

(Step B-3) Drying step iii) After washing, first, an intermediate replacement treatment is performed. That is, after the washing treatment with water, the sample is rinsed in ethanol, and the water remaining in the sample is replaced with ethanol. That is, by performing an intermediate substitution treatment with ethanol, substitution with p-dichlorobenzene becomes possible.

Iv) Thereafter, rinsing is continuously performed in liquid p-dichlorobenzene which is a rinsing liquid for drying treatment. At this time, p-dichlorobenzene was previously heated to about 70 ° C.
Keep liquid.

V) Subsequently, the liquid p-dichlorobenzene adhering to the surface of the sample is cooled and solidified. To do so, a sample may be taken out of liquid p-dichlorobenzene and left to stand. By leaving the sample, the temperature of the sample becomes about room temperature, and the liquid p-dichlorobenzene attached to the sample solidifies.

Vi) Finally, solid p-dichlorobenzene is removed from the sample by sublimation, and the drying process is completed. This sublimation may be left in an appropriately ventilated place, as in the case of coagulation described above.

By performing the above steps i) to vi) successively, the etching process is completed.

However, of the above steps, steps i) to iv), that is, steps until the sample is transferred into liquid p-dichlorobenzene, must be performed continuously. The reason is,
This is because the sample needs to be kept in a non-dried state.

As described above, the rinsing liquid for drying treatment
The reason why the drying process using p-dichlorobenzene is simple is that
This is because all the conditions (conditions A) to (condition C) described above are satisfied, and in addition, an additional condition (condition D-2) is also satisfied.

By using the above etching method, a microstructure having voids can be manufactured.

[Method of Manufacturing Microstructure by Sacrificial Layer Etching Using p-Dichlorobenzene 2] In the above-mentioned drying step using p-dichlorobenzene as the rinse for drying treatment, the time required for drying, in particular, When it is desired to reduce the time required for sublimation, the drying process may be performed while performing a pressure reducing operation using a vacuum device.

In this case, a simple oil rotary vacuum pump may be used as a vacuum device to reduce the pressure appropriately. By performing such a simple decompression operation, the drying process can be completely completed. The time required for this drying process is
It depends on the size of the sample and the amount of p-dichlorobenzene adhering to the sample, but in any case, it is about several minutes.

[Method of Manufacturing Microstructure by Sacrificial Layer Etching When Using Substance Other Than p-Dichlorobenzene]
Even when a substance other than p-dichlorobenzene is used,
A microstructure can be manufactured in a similar manner.

In particular, for naphthalene or camphor, which exhibits sublimability at normal temperature and pressure, the same effect can be obtained by the same procedure as for p-dichlorobenzene. However, when these are used, it is necessary to heat them to the respective melting points shown in Table 1 above in order to make them liquid. Of course, if it is desired to reduce the time required for drying, a simple vacuum device may be used as in the case of p-dichlorobenzene.

Further, p-toluidine, tetrahydrofurfuryl alcohol, cyclohexanol, 1-methoxy-2-
Among the substances shown in Table 1 above, such as propanol, which do not exhibit sublimation at normal temperature and normal pressure, the drying treatment may be performed while performing a pressure reducing operation using a vacuum device.
In this case, a simple vacuum apparatus may be used as in the case of p-dichlorobenzene.

Further, even when a eutectic mixture containing at least one of the substances shown in Table 1 above is used, the drying treatment can be similarly performed.

By using the above substances as a rinsing liquid for drying treatment, a microstructure can be manufactured with good yield.

[Application Example 1 of Drying Method of the Present Invention] The dry processing method of the present invention is not particularly related to the kind of the etchant used for wet etching, and therefore, in addition to the above-described sacrificial layer etching. It can be used for various etchings.

However, in many cases, water is used as the rinsing liquid for the washing treatment. If the rinsing liquid for the drying treatment to be used is not water-soluble or not good, ethanol or the like is required before the rinsing for the drying treatment is performed. May be performed by a water-soluble organic compound.

When an organic solvent is used as an etchant, a rinse for cleaning may be used in place of a rinse for drying. Alternatively, in some cases, an organic compound that can be substituted for the rinsing liquid for drying treatment is used as the rinsing liquid for cleaning treatment. Therefore, in such a case, the above-described intermediate replacement processing becomes unnecessary.

Furthermore, the above-mentioned drying treatment method of the present invention
There is no particular limitation on the shape and size of the sample to be dried, and the sample can be used for objects of various shapes as long as it is larger than the above-described micromachine. In particular, it is suitable for producing dry granules.

[Application Example 2 of Drying Method of the Present Invention] Here, one application example of the drying method of the present invention will be described.

The freeze-drying method of the present invention can be used, for example, when freeze-drying a porous body such as a ceramic molded body.
Especially effective. The reason is that the use of the freeze-drying method has the following advantages.

(3-1) Fine powder with less contamination can be obtained.

(3-2) Fine powder can be easily formed.

(3-3) The powder composition can be made uniform.

(3-4) The activity of the powder is increased.

(3-5) A porous powder is obtained.

From the above advantages, a high-purity porous ceramic can be obtained by using the freeze-drying method.

However, in the prior art, water or benzene, which is a solvent for dissolving the ceramic raw material powder, is freeze-dried. However, there is a problem similar to the above-mentioned problem, and a special device is required. Needed. Therefore, considering the manufacturing cost, it is not a particularly effective method and has not been generally used.

On the other hand, if a substance having sublimability under normal temperature and normal pressure, such as p-dichlorobenzene, which is one of the rinsing liquids for drying treatment of the present invention, is used, the above-described special apparatus is not required and the above-described apparatus can be easily prepared. Freeze-drying can be performed.

[0147]

【Example】

[Example 1] An example relating to the vapor pressure range of a substance that can be used in the rinsing liquid for drying treatment of the present invention will be described below.

In this example, a microbridge made of a polycrystalline Si film was formed on a substrate made of single-crystal Si. Here, the thickness of the polycrystalline Si film forming the microbridge is 0.3 μm.
And Further, in order to unify the conditions of the drying treatment, all the substances in Table 2 below were subjected to the drying treatment at 20 ° C. under reduced pressure. The decompression work was performed using an oil rotary vacuum pump.

After the drying treatment, the microbridges using the respective rinsing liquids for drying treatment were observed using a microscope, and the presence or absence of defects such as sticking or destruction of the microbridges on the substrate was examined.

Table 2 below summarizes the substances used as the rinsing liquid for the drying treatment in this example, their vapor pressures, and the results of observation, that is, the presence or absence of defective samples.

[0151]

[Table 2]

As shown in Table 2, defects were found in the samples which were dried using diphenyl ether and t-butyl alcohol shown in Comparative Examples. The content of the defect is
Some or all of the microbridge was destroyed. On the other hand, in the sample subjected to the drying treatment using the naphthalene, p-dichlorobenzene, and 1-methoxy-2-propanol of this example, no defect was found, and the microbridge was formed without breaking. I was

[Embodiment 2] Next, an embodiment relating to a method for manufacturing a microstructure according to the present invention, and particularly to a method for manufacturing a microstructure having a structure supported in a partially floating state from a substrate, will be described. Show. In this example, p-dichlorobenzene, which is particularly preferable as a rinsing liquid for drying treatment, was used.
The example which manufactured the microbridge is shown.

FIG. 1 is a perspective view of a microbridge formed by using the method for manufacturing a microstructure according to the present invention. Figure 1
, 1 represents a substrate, and 3 represents a microbridge. FIG. 2 is a process diagram showing a process for manufacturing a microbridge manufactured using the method for manufacturing a microstructure of the present invention. In FIG. 2, 1 indicates a substrate, 2 indicates a sacrificial layer portion, and 3 indicates a microbridge. In particular, FIG. 2C is a cross-sectional view taken along the line AA of FIG.

First, the step shown in FIG. 2A will be described.

On a substrate 1 made of single crystal Si, a sacrificial layer 2
It was formed a SiO ₂ film serving as. SiO ₂ to be the sacrificial layer portion ₂
The film had a thickness of 3 μm and was formed using a plasma CVD apparatus.

Subsequently, the SiO ₂ film was patterned into a predetermined shape by photoetching to form a sacrificial layer portion 2. Note that photoetching is an etching method using photolithography.

Next, the step shown in FIG. 2B will be described.

On the sacrificial layer portion 2, a polycrystalline Si film serving as the microbridge 3 was formed. The thickness of the polycrystalline Si film serving as the microbridge 3 was 0.3 μm, and was formed using an LPCVD apparatus.

Subsequently, a microbridge 3 was formed by patterning into a predetermined shape by this polycrystalline Si film photoetching method. However, this micro bridge 3 has a width
It has a crosslinked structure of 10 μm and length of 200 μm. The etching was performed by RIE using CF4. However, RIE is Reactive Ion Etching.

Through the above steps, the sacrificial layer portion 2 and the microbridge 3 were formed on the substrate 1.

Here, sacrifice layer etching is performed as follows. In addition, among the following steps, i) to iv) are performed continuously, and care must be taken so that the sample does not dry.

(Step B-1) Etching Step i) The sample on which the sacrificial layer portion 2 and the microbridge 3 are formed is immersed in a sacrificial layer etching etchant to perform etching. At this time, as the etchant for etching the sacrificial layer, the SiO 2 forming the sacrificial layer portion 2 is used.
Select an etchant that selectively etches only two films. In this example, BHF was used as such an etchant. However, BHF means buffered hydrofluoric acid B
uffered Hydrofluoric acid.

(Step B-2) Cleaning step ii) After the completion of etching with BHF, rinsing was performed in running water for about 5 minutes to remove BHF attached to the sample.

(Step B-3) Drying step iii) Subsequently, an intermediate substitution treatment was performed. In this example, the sample that had been washed with water was moved into ethanol,
I rinsed. By this intermediate replacement process, water adhering to the sample was replaced with ethanol.

Iv) Intermediate The sample after the intermediate treatment was transferred into liquid p-dichlorobenzene and rinsed. At this time, p-dichlorobenzene was heated to 75 ° C. and melted. At this time, the temperature was kept constant using a water bath.

V) Thereafter, the sample rinsed with liquid p-dichlorobenzene is taken out, left to stand, and cooled to room temperature. At this time, it is necessary to cool the sample so that the p-dichlorobenzene attached to the sample solidifies in a relatively short time. In addition, a relatively short period of time means a period in which molten p-dichlorobenzene does not evaporate in a liquid state.

As a specific cooling method, the simplest method is to keep it at room temperature as it is. further,
If you need to solidify more quickly, for example,
What is necessary is just to use a plate-shaped object made of a substance having a large heat capacity as an underlay, and then cool it. Such underlays include copper plates that are water cooled to room temperature.

Vi) After coagulating p-dichlorobenzene,
The sample was left in a moderately ventilated place for about 2 hours.

As a result of performing the above steps i) to vi), p
-Dichlorobenzene was completely sublimated and the drying process was completed.

After the drying treatment, the sample was observed using a microscope, and the presence or absence of breakage of the microbridge was examined.
As a result, a microbridge as shown in FIG. 1 (c) was formed. In addition, in the sample manufactured in this example, defects such as sticking of the microbridge to the substrate and destruction did not occur.

Therefore, the freeze-drying step can be easily performed in a room at normal pressure and normal temperature by using the drying treatment method using p-dichlorobenzene which is the rinse solution for drying treatment of the present invention. In addition, by using a method for manufacturing a microstructure using this drying treatment method, a microstructure having a structure supported in a state of being partially lifted from a substrate with high yield can be manufactured.

In the above embodiment, the case where the microbridge is formed on the substrate has been described as an example. However, the present invention is not limited to this, and other portions are supported in a state of being floated from the substrate. A microstructure having such a structure, for example, a cantilever, a diaphragm, an actuator, or the like can be manufactured by a similar method for manufacturing a microstructure.

[Embodiment 3] With respect to the example of the microbridge shown in Embodiment 2 above, an example in which a vacuum apparatus is used in the drying process will be described below.

In this example, the above step iv), ie, p
-The same procedure as in Example 2 was performed up to the drying treatment rinsing using dichlorobenzene. Thereafter, using a vacuum apparatus, p-dichlorobenzene was coagulated and sublimated.

That is, the sample rinsed with p-dichlorobenzene was put into a vacuum device, and the pressure was reduced to about 104 Pa or less using an oil rotary vacuum pump. As a result of continuing this state for about 5 minutes, p-dichlorobenzene was completely sublimated, and the drying treatment was completed.

In this case, p-dichlorobenzene gradually became a sponge and sublimated.

[0178] Also in this example, after the drying treatment,
The sample was observed with a microscope in the same manner as in Example 2 above, but no defect was found.

As described above, in particular, when it is desired to reduce the time required for sublimation of p-dichlorobenzene, lyophilization may be performed using a vacuum device of a simple exhaust device.

It should be noted that the present invention is not limited to this example, and it may be used in the manufacture of a microstructure having a structure supported in a state of being partially floated from the substrate similarly to the second embodiment. it can.

[Embodiment 4] An embodiment of a method for manufacturing a micro gear according to the present invention, particularly, a method for manufacturing a micro gear as an example of a micro structure having a structure including a rotating portion on a substrate will be described. In this embodiment, an example is shown in which a microgear is manufactured using p-dichlorobenzene, which is particularly preferable as a rinsing liquid for drying treatment.

FIG. 3 is a perspective view of a minute gear made by using the method for manufacturing a minute structure of the present invention. In FIG. 3, 1 indicates a substrate, 4 indicates a rotating shaft, and 5 indicates a gear. FIG. 4 is a process chart showing a manufacturing process of a minute gear manufactured using the method for manufacturing a micro structure of the present invention.
In FIG. 4, 1 denotes a substrate, 2 denotes a sacrifice layer portion, 4 denotes a rotating shaft, and 5 denotes a gear. Also, (d) of FIG.
It is a BB sectional view of.

First, the step shown in FIG. 4A will be described.

On a substrate 1 made of single-crystal Si, a polycrystalline Si film serving as a rotation axis 4 was formed. However, the rotating shaft 4 has a gear supporting portion at a lower portion. The thickness of the polycrystalline Si film serving as the rotation axis 4 is 0.2 μm at the lower supporting portion, and 3 μm at the other axis portion. Note that this polycrystalline Si film was formed using an LPCVD apparatus.

Subsequently, this polycrystalline Si film was patterned into a predetermined shape by photoetching in the same manner as in Example 2 to form a rotating shaft 4 including a gear supporting portion.

Next, the step shown in FIG. 4B will be described.

A PSG film to be the sacrifice layer portion 2 was formed. The PSG film serving as the sacrificial layer portion 2 had a thickness of 0.4 μm, and was formed using a plasma CVD apparatus. However, PSG is phosphorus glass Phosphosilicate Glass.

Next, the step shown in FIG. 4C will be described.

On the sacrifice layer portion 2, a polycrystalline Si film serving as the gear 5 was formed. The thickness of the polycrystalline Si film to be the gear 5 is 3 μm
And a film was formed using an LPCVD apparatus. Note that this polycrystalline Si film was also patterned into a predetermined shape by the same photoetching method as in Example 2 to form the gear 5.
However, this gear 5 has a maximum major axis of about 100 μm.

By the above steps, the sacrificial layer portion 2, the rotating shaft 4, and the gear 5 were formed on the substrate 1.

Thereafter, the sacrifice layer was etched in the same manner as in Example 2 to produce a microstructure.

This embodiment is also similar to the embodiment 2 described above.
As in the above, as a result of observing the sample with a microscope, no defect such as sticking of the gear to the substrate, breakage, or detachment from the rotating shaft was found at all.

Further, no defect was found in the drying treatment using the same vacuum apparatus as in Example 3.

In the above embodiment, the case where the minute gear is formed on the substrate has been described as an example. However, the present invention is not limited to this, and has a structure including a rotating part on another substrate. A microstructure, for example, a motor, a rotary driver, or the like can be manufactured by a similar method for manufacturing a microstructure.

[Embodiment 5] Next, another embodiment of the method for manufacturing a microstructure according to the present invention will be described. In this example, p-type not having sublimability as a rinsing liquid for drying treatment was used.
An example is shown in which microbridges and microgears were produced using toluidine and tetrahydrofurfuryl alcohol.

First, the microbridge was manufactured by the same patterning method as in the second embodiment, and the micro gears were manufactured by the same patterning method as in the fourth embodiment.

However, during the drying treatment, as in Example 3, the pressure was reduced to about 104 Pa or less using an oil rotary vacuum pump or the like.

As a result, no defect was found for any of them.

Further, since tetrahydrofurfuryl alcohol is water-soluble, iii) of Example 2 above
, Ie, the drying treatment was performed without the intermediate replacement treatment with ethanol. As a result, there was no defect.

In the above embodiment, the case where the microbridge or the minute gear is formed on the substrate has been described as an example. However, the present invention is not limited to this, and the present invention is used for another method of manufacturing a minute structure. be able to.

[Embodiment 6] An embodiment showing the application of the drying treatment method of the present invention to articles other than microstructures will be described. In particular, the rinsing liquid for drying treatment of the present invention.
An example in which p-dichlorobenzene is used for the production of a molded ceramic article will be described. However, in this case, p-dichlorobenzene, which is the rinse solution for drying treatment of the present invention, was used as a solvent to be mixed with the ceramic raw material powder.

The ceramic molded body was manufactured according to the following procedure basically according to a conventional method.

(Step C-1) Mixing Step Ceramic raw material powder and p-dichlorobenzene as a solvent were mixed. However, here, La ₂ O ₃ , SrC
A mixture of O ₃ and MnO _{2 so as} to have a desired composition was used.

(Step C-2) Molding Step The mixture of the ceramic raw material powder and the solvent was molded into a desired shape to obtain a green sheet.

(Step C-3) Drying Step The green sheet was cooled. This allows the liquid
p-Dichlorobenzene was coagulated.

After that, leave it in a moderately ventilated place,
p-Dichlorobenzene was sublimated.

Thus, the drying process has been completed.

(Step C-4) Firing Step The green sheet after the drying treatment was fired. As a result, a porous ceramic molded body was obtained.

As described above, by performing the drying treatment using p-dichlorobenzene which is one of the rinsing liquids for the drying treatment of the present invention, the drying treatment was easily performed. The ceramic material to be used does not need to be limited to the above, and various generally used ceramic materials can be used.

Therefore, it is clear that the drying treatment method using the rinsing liquid for drying treatment of the present invention is very simple and extremely effective also in the production of a ceramic molded body.

[0211]

The effects of the present invention are as follows.

(Effect 1) By using an organic compound which is solid at 20 ° C. and has a vapor pressure of 0.05 mmHg or more and 8 mmHg or less at that temperature as a rinsing liquid for drying treatment, defects such as breakage of the microstructure can be prevented. The drying process could be performed without causing any generation.

(Effect 2) In particular, by using the above-mentioned rinsing liquid for drying treatment having a melting point of 40 ° C. or more and 100 ° C. or less, complicated temperature control and humidity control are not required, and a cooling device or the like is required. A simple and low-cost drying process that did not particularly require the special equipment and equipment described above could be performed.

(Effect 3) Further, by using a rinsing solution for drying treatment which exhibits sublimability under normal temperature and normal pressure, such as p-dichlorobenzene, a special device and equipment such as a vacuum device are not particularly required, and it is simple and convenient. A low-cost drying process could be performed.

(Effect 4) By using the above-mentioned drying treatment method, etching by the sacrificial layer etching with a good yield can be performed irrespective of the shape of the object to be etched and the type of the etching solution.

(Effect 5) By using the above-mentioned etching method, it has become possible to provide an inexpensive and high-yield microstructure manufacturing method.

(Effect 6) In addition, by using a rinse liquid for drying treatment which exhibits sublimability at normal temperature and normal pressure, such as the above-mentioned p-dichlorobenzene, the above-mentioned ceramics and other dried granular materials can be produced simply and at low cost. A manufacturing method could be provided.

[Brief description of the drawings]

FIG. 1 is a perspective view of a microbridge created by using the method for manufacturing a microstructure of the present invention.

FIG. 2 is a process diagram showing a manufacturing process of a microbridge manufactured by using the method for manufacturing a microstructure of the present invention, and in particular, (c) is a cross-sectional view taken along the line AA of FIG.

FIG. 3 is a perspective view of a minute gear manufactured by using the method for manufacturing a minute structure of the present invention.

FIG. 4 is a process diagram showing a manufacturing process of a minute gear manufactured using the method for manufacturing a micro structure of the present invention, and in particular, FIG.
Is a sectional view taken along the line BB in FIG.

[Explanation of symbols]

 1 Substrate 2 Sacrificial layer 3 Micro bridge 4 Rotation axis 5 Gear

Claims (18)

[Claims] 1. A rinsing liquid for drying treatment used for performing a drying treatment, which is an organic compound which is solid at 20 ° C. and has a vapor pressure at the temperature of 0.05 mmHg to 8 mmHg. Characteristic rinsing liquid for drying treatment. 2. The organic compound having a melting point of 40 ° C. or more and 100 ° C.
2. The rinsing solution for drying treatment according to claim 1, wherein the rinsing solution is at or below a temperature. 3. The rinsing liquid for drying treatment according to claim 1, wherein the organic compound has sublimability at normal temperature and normal pressure. 4. The rinsing solution for drying treatment according to claim 1, wherein the organic compound is p-toluidine. 5. The method according to claim 1, wherein the organic compound is tetrahydrofurfuryl alcohol.
The rinse solution for drying treatment according to the above. 6. The rinsing liquid for drying treatment according to claim 1, wherein the organic compound is p-dichlorobenzene. 7. The rinsing liquid for drying treatment according to claim 1, wherein the rinsing liquid is used in a drying step after a wet etching step or after a cleaning step performed continuously to the wet etching step. . 8. A method for drying an object, comprising: using the rinsing liquid for drying according to any one of claims 1 to 6 to solidify the rinsing liquid for drying; Drying the object by vaporizing it in the state described above. 9. A drying method in a drying step after a wet etching step or after a cleaning step performed continuously to the wet etching step, wherein the drying step is performed using the drying method according to claim 8. Drying treatment method. 10. An etching method by wet etching, comprising a drying step using the drying method according to claim 8 after a wet etching step or after a cleaning step performed continuously to the wet etching step. An etching method characterized by the above-mentioned. 11. The etching method according to claim 10, wherein said etching method is a sacrifice layer etching for etching a sacrifice layer portion to be selectively removed. 12. The etching method according to claim 11, wherein the sacrificial layer portion is a layer used for forming a microstructure having voids. 13. The sacrifice layer portion may be a part or all of a layer formed on a substrate different from the substrate, or a layer different from the substrate formed on a part of the substrate. 13. The etching method according to claim 11, wherein 14. The etching method according to claim 13, wherein the layer different from the substrate is made of a material having a different crystal structure from a material forming the substrate. 15. The etching method according to claim 13, wherein the layer different from the substrate is made of a material having a composition different from a material forming the substrate. 16. A method for manufacturing a microstructure having voids, wherein the etching method according to claim 10 is used. 17. The method for manufacturing a microstructure according to claim 16, wherein the microstructure has a structure in which the microstructure is supported in a state of being partially floated from a substrate. 18. The method for manufacturing a microstructure according to claim 16, wherein the microstructure has a structure including a portion rotating on a substrate.