JP4546314B2 - Fine structure drying method and apparatus - Google Patents

Description

  The present invention relates to a novel microstructure drying method and apparatus.

  Conventionally, in order to manufacture a large-scale, high-density, high-performance device, a resist formed on a silicon wafer is exposed, developed, rinsed and dried to form a pattern, and then coated, etched, and rinsed. It is manufactured through a process such as drying. In particular, the resist is a polymer material that is sensitive to light, X-rays, electron beams, etc., and in each process, a chemical solution such as a developer or a rinse solution is used in the development and rinse cleaning process, so the rinse cleaning process After that, a drying process is essential.

  In this drying process, when the space width between resist patterns formed on the substrate becomes as fine as 100 nm or less, the Laplace force (capillary force) acts between the patterns due to the surface tension of the chemical remaining between the patterns. The problem of falling occurs.

  On the other hand, for example, the manufacture of MEMS (Micro Electromechanical System) parts, which are three-dimensional microstructure parts with fine movable parts and structures such as acceleration sensors and actuators, form a microstructure that includes movable parts with an etching solution such as hydrofluoric acid. A process of removing (cleaning) the etching solution with pure water rinsing, and a process of drying. Also in this drying process, the surface tension due to the chemical solution remaining between the fine structures acts like the resist pattern, and the phenomenon that the movable part is fixed to the substrate occurs.

Patent Document 1 discloses a drying process for reducing the surface tension acting between fine structures in order to prevent pattern collapse and element sticking due to the action of the surface tension of a chemical solution remaining between fine structures such as resist patterns and MEMS. And a method using a supercritical fluid such as carbon dioxide. This drying method using a supercritical fluid such as carbon dioxide has the following basic steps.
(1) Residual liquid such as water contained in a sample that is not soluble in a liquid or a fluid in a supercritical state can be dissolved in carbon dioxide in the case where carbon dioxide is used in advance as a chemical solution that is soluble in fluid, for example, as a drying fluid. A step of replacing with a rinsing liquid such as a soluble organic solvent such as ethanol or 2-propanol or a mixture thereof.
(2) A step of placing a sample immersed in or wetted with a rinsing liquid, specifically, a state where the rinsing liquid is placed on a substrate in a high-pressure container serving as a high-pressure container, and sealing the high-pressure container.
(3) A step of introducing a liquid or supercritical dry fluid into the high-pressure vessel and increasing the pressure to a predetermined pressure.
(4) The liquid or supercritical dry fluid introduced into the high-pressure vessel is heated to change its specific gravity to a specific gravity different from that of the rinsing liquid, and the rinsing liquid is collected at the upper or lower part of the high-pressure vessel to obtain the liquid or supercritical A step of replacing the fluid in a state and discharging the collected rinse liquid out of the high-pressure vessel.
(5) A step of raising the pressure and raising the temperature of the high-pressure vessel and its dry fluid above the critical point after the rinsing liquid is replaced.
(6) A step of gradually discharging the fluid in a supercritical state from the high-pressure vessel to reduce the pressure to atmospheric pressure.
(7) A step of taking out the substrate from the high-pressure vessel.

JP 2004-335675 A

  However, in the conventional drying method using supercritical fluid, the rinsing liquid is selectively discharged out of the high-pressure vessel by controlling the temperature and temperature of the entire high-pressure vessel to a temperature lower than the critical temperature and controlling the state and density of the drying fluid. Although the drying time was considerably shortened compared to the "critical point drying method" that can be performed, it took time to raise and lower the temperature to control the entire high-pressure vessel with a large heat capacity from 5 ° C to 50 ° C. .

  An object of the present invention is to provide a large-diameter substrate having a diameter of 100 mm or more on which a fine pattern in which pattern collapse or element sticking may occur due to the influence of the surface tension of the rinsing liquid only by locally heating the drying fluid during drying. It is an object of the present invention to provide a fine structure drying method and apparatus capable of drying uniformly and efficiently in a short time.

In the present invention, a substrate having a fine structure immersed or wet in a rinsing liquid is placed in a high-pressure vessel, and a drying fluid having a specific gravity different from the specific gravity of the rinsing liquid is introduced into the high-pressure vessel and filled, and then the drying is performed. top or of the high-pressure vessel the rinsing liquid from the selectively high-pressure vessel of the high-pressure container filled with a fluid by utilizing the difference in specific gravity between the drying fluid and the rinsing liquid is inclined to the predetermined angle with the substrate and the inclined After discharging from the inside of the high-pressure vessel through a rinse liquid discharge port provided in at least one of the lower parts , the drying fluid is decompressed to atmospheric pressure while locally heating to a critical temperature or higher, and the dry fluid is supplied to the rinse liquid discharge port. in shall then discharged to the high pressure vessel outer than provided separately dry fluid outlet, preferably, by locally heating the fluid near the substrate, the raw convection in the fluid near the substrate In the microstructure drying treatment method comprising the step of promoting the dissolving rinsing liquid at the allowed dry fluid.

  The surface tension mainly due to the difference in surface energy acts on the interface between the two fluids. When the solubility between the two fluids is high, the higher the solubility and the dissolution rate, the higher the surface tension. It is known to become smaller.

In the supercritical drying method, there is a two-layer interface between the rinsing liquid and the liquid or the supercritical drying fluid, and surface tension acts on these interfaces. Since the fluid uses a combination of compatible materials, the surface tension acting on the interface between the rinse liquid and the fluid is reduced.
For example, carbon dioxide used as a drying fluid has an organic solvent property equivalent to hexane.
When using carbon dioxide as a drying fluid, organic solvents such as alcohol, acetone, and isoamyl acetate, which are known to dissolve in carbon dioxide, are used, but the solubility in liquefied carbon dioxide is not high, and surface energy is present at the interface. Surface tension due to the difference between the two acts.

  However, the size of the surface tension at the interface between the supercritical state or the liquefied carbon dioxide and the rinsing liquid such as alcohol, acetone, and isoamyl acetate is not measured at present, and according to the experimental results of the inventors, the space width is 20 nm. It has been found that the resist pattern having a line width of 40 nm and a thickness of 160 nm does not collapse due to the influence of the surface tension at the interface between the supercritical state or the liquefied carbon dioxide and the rinsing liquid such as alcohol, acetone or isoamyl acetate.

  On the other hand, it is known that surface tension does not act on the phase change from a liquid to a supercritical state gas, and the conventional critical point drying method uses this phenomenon. Since the surface tension acts on the interface of the rinsing liquid, even if the supercritical drying method is applied, the influence of the surface tension cannot be completely eliminated, but it does not satisfy the required surface tension reduction effect. it can.

  Therefore, the conventional critical point drying method is not necessarily required to change the state of the liquid from the liquid to the gas via the supercritical state, and the required surface tension can be obtained even if there is a step having a state change across the gas-liquid curve. The effect of reducing can be satisfied.

Focusing on the fact that the magnitude of the surface tension that acts when changing the state from liquid to gas becomes smaller as it approaches the critical point in the gas-liquid curve,
The state change is performed so as to satisfy the condition of making the (surface tension when changing the state of the fluid from liquid to gas) smaller than (the surface tension acting on the interface between the rinse liquid and the fluid).

  For example, when liquefied carbon dioxide is used as the dry fluid and the rinse liquid is applied as 2-propanol to the resist pattern described above, the pressure is gradually reduced to atmospheric pressure under the conditions of pressure 7.5 MPa and temperature 25 ° C. From the experiment, it is possible to obtain the same effect of reducing the surface tension, that is, the drying result when the phase is changed to gas through the supercritical state of pressure 7.5 MPa and temperature 35 ° C. I understood.

  After filling the inside of the high-pressure vessel with the drying fluid, the rinsing solution is discharged from the inside of the high-pressure vessel, and the temperature control function installed near the substrate causes the drying fluid to generate convection over the critical temperature to generate the rinsing solution. It is preferable to promote dissolution of the drying fluid.

  By heating the temperature control function located near the base to a temperature above the critical temperature, a supercritical state and a liquid state are formed near the base in the high-pressure vessel, and the rinsing liquid is promoted to dissolve with the dry fluid. It is preferable to control the heating so that the convection is appropriate and the temperature of the substrate does not exceed the critical temperature.

  In particular, the present invention relates to a rinsing collected in a lower part of a high-pressure vessel after filling a dry fluid in a high-pressure vessel having an internal volume of 1 liter or less in which a substrate having a fine structure immersed or wet in a rinsing liquid is installed. The liquid is discharged out of the high-pressure container, and then the rinsing liquid is dissolved in the fluid while locally heating the dry fluid in the vicinity of the substrate to a temperature above the critical temperature, and the pressure is reduced to atmospheric pressure while heating in the same manner. The time required for drying from the introduction of the drying fluid into the inside until the pressure is reduced to atmospheric pressure can be performed within 10 minutes.

The present invention also provides
A substrate mounting table for holding a substrate having a fine structure immersed or wet in a rinse solution;
A high-pressure container for drying the substrate held on the substrate mounting table;
And introducing means for introducing a specific gravity different from the specific gravity of the dry fluid of the rinsing liquid into the high pressure vessel,
Tilting means for tilting the high-pressure vessel together with the substrate;
Rinsing liquid discharging means for discharging the rinsing liquid from the inside of the high-pressure vessel filled with the drying fluid from a rinsing liquid discharge port provided on at least one of the top and bottom of the inclined high-pressure vessel ;
A temperature adjustment function for locally heating the dry fluid by heating with a heating wire provided in a pressure-resistant tube structure disposed in the vicinity of at least one of the substrates above and below the substrate, or by inflow of thermal fluid into the piping;
The fine-structure drying apparatus has a drying fluid discharge means that discharges the drying fluid from the high-pressure container through a drying fluid discharge port provided separately from the rinse liquid discharge port while locally heating the drying fluid by a temperature control function.

Furthermore, the present invention provides
A substrate mounting table for holding a substrate having a fine structure immersed or wet in a rinse solution;
A high-pressure container for drying the substrate held on the substrate mounting table;
And introducing means for introducing a specific gravity different from the specific gravity of the dry fluid of the rinsing liquid into the high pressure vessel,
Tilting means for tilting the high-pressure vessel together with the substrate;
Rinsing liquid discharge means for discharging the rinsing liquid from the rinsing liquid discharge port provided in at least one of the uppermost part and the lowermost part of the inclined high pressure container from the inside of the high pressure container filled with the dry fluid;
A temperature adjusting function for locally heating the drying fluid provided in the vicinity of at least one of the top and bottom of the substrate;
Pressure control means for controlling the pressure in the high-pressure vessel that holds the dried fluid in a mixed state of a supercritical state and a liquid state by a temperature adjustment function;
The temperature control the drying fluid the rinsing liquid discharge port with heating and is in the microstructure drying apparatus for chromatic and drying fluid discharge means for discharging the high pressure vessel outside than separately provided dry fluid outlet.

  The temperature adjustment function has a setting means for setting to a predetermined temperature and a control means for keeping the temperature constant, and the rinse liquid discharge ports are located at the uppermost and lower parts of the high-pressure vessel when the rinse liquid is discharged. It is preferable to arrange at least one side.

  According to the present invention, only by locally heating only the drying fluid at the time of drying, a fine pattern having a fine pattern that can cause pattern collapse or element sticking due to the influence of the surface tension of the rinse liquid at the time of drying is formed. It is possible to provide a fine structure drying method and apparatus capable of efficiently and uniformly drying a large-diameter substrate in a short time.

  Hereinafter, the best mode for carrying out the present invention will be described with reference to specific examples.

  FIG. 1 is a schematic cross-sectional view showing an example of the microstructure drying apparatus of the present invention. The high-pressure vessel 103 which is a high-pressure vessel is composed of an upper lid 105 and a lower vessel portion 124, and the lid 101 is opened to install the substrate 101.

  The high-pressure vessel 103 has tilting means that can tilt from horizontal to vertical as shown in FIG. The high-pressure vessel 103 is provided with rotating shafts having tilting gears perpendicular to the paper surface on both sides of the lower container 124, and can be tilted to the left and right sides from the horizontal to 90 degrees with respect to the paper surface by a motor.

  The filter 112 and the valve 113 are fixed to the lower container 124, and are connected to the pressure control device 123 by a high-pressure flexible pipe. Further, the back pressure control valve 109 and the valve 110 are connected to the lid 105, the valve 117 and the pressure control valve 118 are connected. Are fixed to the lower container 124, their tips are connected by high-pressure flexible piping, and can be tilted as shown in FIG.

  The substrate 101 is subjected to a development and wet etching process and a fine structure is formed on the surface, and then washed and rinsed with an organic solvent such as alcohol, and the rinse liquid 102 is placed on the entire surface. And installed on the substrate installation table 104 provided in the high-pressure vessel 103.

  In the high-pressure vessel 103, a high-pressure pump 114 and a liquid carbon dioxide vessel 115 are connected through a valve 113, and a pressure control valve 118 is connected through a valve 117 so that the internal volume thereof is within 1 liter.

  The high-pressure vessel 103 is connected to the lid 105 via the valve 110 and the lower vessel portion 124 via the valve 107, respectively. When the set pressure is exceeded, the fluid in the high-pressure vessel is discharged from the discharge port 119 or the discharge port 120. Alternatively, the rinsing liquid 102 is discharged.

  The high-pressure vessel 103 is provided with a temperature adjustment function 111 provided in the vicinity thereof on the substrate 101 and a temperature adjustment function 106 provided in the vicinity thereof under the substrate installation table 104, both of which are pressure-resistant piping made of nonmagnetic stainless steel. A heating medium is circulated in the inside, or a heating wire is provided in the pressure-resistant piping, which is rod-shaped or spiral-shaped, and has a control means for controlling at a predetermined temperature so as to be held at a constant temperature. The temperature adjustment function 111 is set several millimeters above the substrate 103, and can dry the dry fluid in the vicinity thereof locally above the critical temperature without setting the temperature of the substrate 101 above the critical temperature.

  In this example, a step of installing a substrate having a microstructure immersed or wetted in a rinsing liquid in a high-pressure vessel, an introduction step of introducing and filling a dry fluid lighter than the rinsing liquid in the high-pressure vessel, Inclination of the high-pressure container filled with the drying fluid to discharge most of the rinsing liquid in the high-pressure container from the inside of the high-pressure container, and partially heating the drying fluid in the vicinity of the substrate to cause convection, It is a fine structure drying method having a dissolution / replacement step for promoting dissolution / replacement of a rinsing liquid with a dry fluid, and a pressure reduction step for reducing the pressure of the dry fluid to atmospheric pressure while locally heating it. Hereinafter, the drying process of a present Example is demonstrated concretely.

(1) EB resist (ZEP-7000: manufactured by ZEON Corporation) with a film thickness of 220 nm is formed on a silicon substrate having a diameter of 200 mm, dried, drawn with an electron beam, and then developed with normal hexyl acetate for 90 seconds. Then, the substrate 101 which is rinsed with 2-propanol for 100 seconds and has a fine structure formed on the surface is set on the substrate mounting table 104 of the high-pressure vessel 103. At this time, either on top of the substrate 101 is a state where the rinsing liquid 102 consisting of soluble 2-propanol in the liquid carbon dioxide or supercritical carbon dioxide placed on the substrate whole surface, the substrate 101 is immersed in the rinsing liquid 102 State.

(2) After the high-pressure vessel 103 is leveled, the lid 105 is opened, the substrate 101 is placed on the substrate mounting base 104, and the high-pressure vessel 103 is hermetically sealed, and then the valves 117, 107, 110 are closed.

(3) When the valve 113 is opened, liquid carbon dioxide 116 at 25 ° C. at room temperature is introduced into the high-pressure vessel 103. At this time, the pressure control device 123 performs control so that the pressure is increased to 7.5 MPa at about 3 MPa / min so that the fine structure formed on the substrate 101 is not damaged. Further, the liquid carbon dioxide 116 introduced into the high-pressure vessel 103 passes through the filter 112 to remove impurities. Since the rinsing liquid 102 has a higher specific gravity than the liquid carbon dioxide 116 at 25 ° C., the rinsing liquid 102 is in a state surrounded by the liquid carbon dioxide 116 at 25 ° C. while being placed on the substrate 101.

(4) FIG. 2 is a cross-sectional view of the microstructure drying apparatus showing a state in which the high-pressure vessel is inclined. When the high-pressure vessel 103 having a room temperature of 25 ° C. is tilted by the tilting means, most of the rinsing liquid 121 made of 2-propanol on the substrate 101 has a higher specific gravity than the liquid carbon dioxide 116 at 25 ° C. The rinsing liquid 121 collects in the lower part of the inclined high-pressure vessel 103 while hardly dissolving with the liquid carbon dioxide 122 filled in the high-pressure vessel 103.

(5) The liquid carbon dioxide 116 is continuously pumped by the high-pressure pump 114. When the valve 107 is opened, the 2-propanol rinse liquid 121 collected in the lower portion of the inclined high-pressure vessel 103 can be selectively discharged from the back pressure control valve 108 through the rinse liquid discharge port 120.

FIG. 3 is a schematic cross-sectional view showing a state in which liquid carbon dioxide is filled in the high-pressure vessel 103 after most of the rinsing liquid is discharged. The rinsing liquid 121 is discharged from the rinsing liquid discharge port 108, and the inside of the high-pressure vessel 103 is almost filled with only liquid carbon dioxide 122.

(6) The temperature adjusting functions 111 and 106 are controlled to 60 ° C. while the high pressure pump 114 continues to pump the liquid carbon dioxide 116 while the high pressure vessel 103 is inclined. The liquid carbon dioxide 122 in contact with the temperature adjustment functions 111 and 106 is locally heated to 60 ° C. in the supercritical state, and the carbon dioxide 122 in the vicinity of the temperature adjustment functions 111 and 106 becomes almost the control temperature, but the substrate 101 is Heated to about 28 ° C. by heated carbon dioxide 122. In addition, liquid and supercritical carbon dioxide are mixed in the high-pressure vessel 103, and convection of carbon dioxide occurs due to the difference in specific gravity, so that the rinsing liquid remaining between the microstructures on the substrate 101 is liquid or supercritical. Can be replaced by carbon dioxide.

  Further, the temperature adjustment functions 111 and 106 are in the form of several rods or spirals in order to secure a space so that the liquid carbon dioxide 122 generates appropriate convection on the surface of the substrate 103.

  The pressure in the high-pressure vessel 103 is increased by heating, but when the set pressure exceeds 7.5 MPa, carbon dioxide is discharged from the back pressure control valve 109, and the inside of the high-pressure vessel 103 is maintained at 7.5 MPa. Keep for a minute. Thereby, the rinsing liquid remaining between the fine structures can be completely replaced.

  In addition, after the high pressure vessel 103 is returned and heated, it can be tilted while being heated to discharge carbon dioxide, and this can be repeated. Further, by using the vibrator 151, it remains between the microstructures. The rinse liquid can be easily replaced and the drying time can be shortened.

(7) The pumping of the liquid carbon dioxide 116 by the high-pressure pump 114 is stopped, the valves 113 and 110 are closed, the valve 117 is opened to the atmospheric pressure, and the dry fluid is discharged while the temperature adjustment functions 111 and 106 are maintained at 60 ° C. Carbon dioxide is discharged from the pressure control valve 118 through the outlet . When the pressure in the high-pressure vessel 103 reaches atmospheric pressure, the drying is finished, and the substrate 101 is taken out from the high-pressure vessel 103.

  In this change in the state of carbon dioxide, the surface tension of liquid carbon dioxide does not cause the element to adhere to or fall over the fine structure.

  In the present embodiment, the case where carbon dioxide that is in a supercritical state at a relatively low temperature and low pressure is used as the fluid used for drying the microstructure is shown as an example, but the critical pressure of carbon dioxide is 7.38 MPa. The critical temperature is 31 ° C.

  The density of liquid carbon dioxide can be changed from 0.7 g / ml to 0.15 g / ml by changing the pressure from 7.5 MPa and the temperature from 25 ° C. to 60 ° C. When propanol is used as the rinsing liquid, a drying process capable of obtaining a uniform drying result in a short time within approximately 10 minutes can be achieved.

  The present embodiment includes a step of installing a substrate having a fine structure immersed or wet in a rinsing liquid in a high-pressure vessel, and an introduction step of introducing and filling a dry fluid heavier than the rinsing liquid in the high-pressure vessel. After filling the high-pressure vessel with the pre-drying fluid, tilt the high-pressure vessel to discharge the rinsing liquid from the high-pressure vessel, partially heat the drying fluid near the substrate, and replace the rinsing liquid with the drying fluid. In the fine structure drying method, the rinsing liquid is discharged from the high-pressure vessel while the rinsing liquid is discharged and the pressure reducing step is performed to reduce the pressure to the atmospheric pressure while locally heating the drying fluid after discharging the rinsing liquid.

  Hereinafter, the drying process of a present Example is demonstrated concretely. The apparatus in the present embodiment is the same as that in the first embodiment, but the temperature adjusting functions 111 and 106 circulate a heat medium in the pressure-resistant piping made of nonmagnetic stainless steel. The steps up to (2) are the same in this embodiment.

(3) When the valve 113 is opened, the carbon dioxide 116 in a liquid state at 5 ° C. is introduced into the high-pressure vessel 103. At this time, the pressure control device 123 is controlled so that the fine structure formed on the substrate 101 is not damaged and the pressure is increased to about 10 MPa at about 3 MPa / min in order to minimize the turbidity between the rinsing liquid 102 and the liquid carbon dioxide. To do. Liquid carbon dioxide introduced into the high-pressure vessel 103 passes through the filter 112 to remove impurities. Since the rinsing liquid 102 has a specific gravity smaller than that of the liquid carbon dioxide 116 at 5 ° C., the rinsing liquid 102 is separated from the surface of the substrate 101, hardly dissolves with the liquid carbon dioxide 122 filled in the high-pressure vessel 103, and the rinsing liquid 121. Collect at the top of the high-pressure vessel 103.

(4) FIG. 4 is a cross-sectional view of the microstructure drying apparatus showing a state in which the high-pressure vessel is inclined. When the high-pressure vessel 103 is tilted by the tilting means, most of the rinsing liquid 121 made of 2-propanol on the substrate 101 has a specific gravity smaller than that of the liquid carbon dioxide 116 at 5 ° C., so that the rinsing liquid 121 is tilted. Gathered in the upper portion of the high-pressure vessel 103.

  The specific gravity of liquid carbon dioxide at 5 ° C. is 0.95 g / ml, and the specific gravity difference from the specific gravity of propanol, 2-propanol, 0.80 g / ml is about 0.15 g / ml. As shown, 2-propanol collects at the top of the inclined high pressure vessel 103. The pressure increase up to 10 MPa and the temperature decrease up to 5 ° C. may be shifted simultaneously.

(5) The liquid carbon dioxide 116 is continuously pumped by the high-pressure pump 114. When the valve 110 is opened, the 2-propanol rinse liquid 121 collected in the upper part of the inclined high-pressure vessel 103 can be selectively discharged from the back pressure control valve 109 through the rinse liquid discharge port 119.

  As in FIG. 3, the high pressure vessel 103 after most of the rinsing liquid is discharged is filled with liquid carbon dioxide, the rinsing liquid 121 is discharged from the discharge port 109, and the high pressure vessel 103 is almost liquid dioxide. Filled with carbon 122 only.

(6) The temperature adjusting functions 111 and 106 are controlled to 40 ° C. while the high pressure pump 114 continues to pump the liquid carbon dioxide 116 while the high pressure vessel 103 is inclined. The liquid carbon dioxide 122 in contact with the temperature adjustment functions 111 and 106 is locally heated to 40 ° C. in a supercritical state, and the carbon dioxide 122 in the vicinity of the temperature adjustment functions 111 and 106 becomes almost the control temperature, but in the vicinity of the substrate 101. Becomes about 25 ° C. by the heated carbon dioxide 122. Further, liquid and supercritical carbon dioxide are mixed in the high-pressure vessel 103, and the rinsing liquid remaining between the fine structures on the substrate 101 is mixed with the liquid and supercritical state by convection due to the specific gravity difference. Can be replaced by The temperature adjusting functions 111 and 106 are rod-like or spiral having a space so that convection of the liquid carbon dioxide 122 is easily generated on the entire surface of the substrate 103 by heating.

  Then, the pressure in the high-pressure vessel 103 is increased by heating, but when the set pressure exceeds 10 MPa, the pressure is discharged from the back pressure control valve 109, the inside of the high-pressure vessel 103 is kept at 10 MPa, and this state is kept for several minutes. As a result, the rinsing liquid remaining between the microstructures can be almost completely replaced.

(7) The pumping of the liquid carbon dioxide 116 by the high-pressure pump 114 is stopped, the valves 113 and 110 are closed, the valve 117 is opened to the atmospheric pressure, and the dry fluid is discharged while the temperature adjustment functions 111 and 106 are kept at 40 ° C. Carbon dioxide is discharged from the pressure control valve 118 through the outlet . When the pressure in the high-pressure vessel 103 reaches atmospheric pressure, the drying is finished, and the substrate 101 is taken out from the high-pressure vessel 103.

  In this state change, the surface tension of the liquid carbon dioxide does not cause the element to adhere to or fall over the fine structure.

  In the present embodiment, the case where carbon dioxide that is in a supercritical state at a relatively low temperature and low pressure is used as a fluid used for drying the microstructure is shown as an example, but the critical pressure of carbon dioxide is 7.38 MPa. The critical temperature is 31 ° C. The density of liquid carbon dioxide can be changed from 0.65 to 0.90 g / ml by changing the pressure from 10 MPa and the temperature from 0 to 30 ° C. The 2-propanol shown in this example is rinsed. When used as, it is possible to achieve a drying process capable of obtaining a uniform drying result in a short time.

  In this embodiment, a fine structure is formed by etching hydrofluoric acid such as a MEMS sample, and a drying process is performed after rinsing with pure water. Also in this embodiment, the phenomenon that the fine structure including the movable part of the three-dimensional structure such as silicon or resist sticks to the substrate (base part) due to the action of the surface tension in the same manner as the resist pattern causes the device failure. Become. The present invention is applied to prevent this phenomenon.

  Since the pure water of the rinsing liquid is hardly soluble in carbon dioxide in a liquid or supercritical state, it is replaced in advance with rinsing soluble in carbon dioxide. As a rinsing liquid for the MEMS sample of this example, a rinsing liquid in which a hydrocarbon detergent (HCFC) having a specific gravity of 1.55 g / ml and ethanol were mixed at a ratio of 5: 1 was used. Even if the specific gravity of carbon dioxide is controlled, the HCFC placed on the substrate cannot be collected on the upper side of the high-pressure vessel. However, in this embodiment, the high-pressure vessel is changed from 90 degrees on the right to 90 degrees on the left as shown in FIG. By rotating and tilting to any one, the rinsing liquid placed on the substrate can be collected and effectively discharged at the bottom of the tilted high-pressure vessel, and in the same manner as in Example 1, a uniform drying result can be obtained in a short time. Obtainable.

  In the present embodiment, the drying can be performed by the same drying steps as (1) to (7) of the first embodiment.

  In the present example, the reason why the mixed liquid of HCFC and ethanol was rinsed is that ethanol replaces water and HCFC replaces carbon dioxide.

  As described above, according to the present embodiment, even a device such as a MEMS component can be uniformly dried in a short time without sticking a movable portion having a fine structure formed on a large-diameter substrate of 100 mm or more.

It is sectional drawing of the microstructure drying apparatus which concerns on this invention. It is sectional drawing of the fine structure drying apparatus after the inclination of a high-pressure vessel and temperature change in this invention. It is sectional drawing of the fine structure drying apparatus after the rinse liquid discharge | emission in this invention. It is sectional drawing of the fine structure drying apparatus after the inclination of a high-pressure vessel and temperature change in this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 101 ... Board | substrate, 102, 121 ... Rinse solution, 103 ... High pressure vessel, 104 ... Board | substrate installation stand, 105 ... Cover, 106, 111 ... Temperature control function, 107, 110, 113, 117 ... Valve, 108, 109 ... Back pressure Control valve, 112 ... filter, 114 ... high pressure pump, 115 ... liquid carbon dioxide container, 116, 122 ... liquid carbon dioxide, 118 ... pressure control valve, 119, 120 ... rinse liquid discharge port, 123 ... pressure control device, 124 ... Lower container, 125 ... rotating direction, 151 ... vibrator.

Claims (10)

Installing a substrate having a fine structure immersed or wet in a rinsing liquid in a high-pressure vessel; and
An introduction step of introducing and filling a dry fluid having a specific gravity different from the specific gravity of the rinse liquid into the high-pressure vessel;
Inclining the high-pressure vessel filled with the drying fluid with the substrate at a set angle, and utilizing the specific gravity difference between the drying fluid and the rinsing liquid , the top or bottom of the inclined high-pressure vessel A rinse liquid discharge step of selectively discharging from the inside of the high-pressure vessel from a rinse liquid discharge port provided in at least one of the following:
Heating the dry fluid locally above a critical temperature;
A discharging step of discharging from said drying fluid locally with heating under reduced pressure to atmospheric pressure the drying fluid the rinsing liquid discharge port and dry fluid outlet which is provided separately outside the high pressure vessel,
A fine structure drying method characterized by comprising: In claim 1, the microstructure drying treatment the temperature of the substrate and performing the heating so as not to exceed the critical temperature. 3. The method according to claim 1, wherein the drying fluid in the vicinity of the substrate is locally heated to cause an appropriate convection in the drying fluid in the vicinity of the substrate, thereby promoting dissolution of the rinse liquid and the drying fluid. A method of drying a microstructure, characterized by comprising a step of:   4. The microstructure drying method according to claim 1, wherein the heating is performed by a temperature adjustment function installed in the vicinity of the substrate. In any one of claims 1 to 4, the microstructure drying treatment method, which comprises carrying out in a state where the heating before Symbol dry fluid and the state of the supercritical state and the liquid are mixed. 6. The rinse liquid discharge port provided in the uppermost part of the inclined high pressure vessel, wherein the dry fluid having a specific gravity larger than the specific gravity of the rinse liquid is introduced as the dry fluid. From the rinse liquid discharge port provided at the lowermost portion of the inclined high-pressure vessel, and the dry fluid having a specific gravity smaller than that of the rinse liquid is introduced. microstructure drying treatment method, characterized in Rukoto drained.   7. The microstructure drying method according to claim 1, wherein the drying fluid is carbon dioxide. A substrate mounting table for holding a substrate having a fine structure immersed or wet in a rinse solution;
A high-pressure container for drying the substrate held on the substrate mounting table;
Introducing means for introducing a dry fluid having a specific gravity different from that of the rinse liquid into the high-pressure vessel;
Tilting means for tilting the high-pressure vessel together with the substrate;
Rinsing liquid discharging means for discharging the rinsing liquid from the inside of the high pressure container filled with the dry fluid from a rinsing liquid discharge port provided on at least one of the top and bottom of the inclined high pressure container ;
A temperature adjusting function for locally heating the dry fluid by heating with a heating wire provided in a pressure tube disposed in the vicinity of at least one of the upper and lower sides of the substrate, or by inflow of a thermal fluid into the pressure tube;
A drying fluid discharge means for discharging the drying fluid to the high pressure vessel outer than the rinsing liquid discharge port and dry fluid outlet which is provided separately with heating by the temperature control,
A fine structure drying apparatus comprising: A substrate mounting table for holding a substrate having a fine structure immersed or wet in a rinse solution;
A high-pressure container for drying the substrate held on the substrate mounting table;
And introducing means for introducing a specific gravity different from the specific gravity of the dry fluid of the rinsing liquid to the high-pressure vessel,
Tilting means for tilting the high-pressure vessel together with the substrate;
Rinsing liquid discharging means for discharging the rinsing liquid from the inside of the high pressure container filled with the dry fluid from a rinsing liquid discharge port provided on at least one of the top and bottom of the inclined high pressure container ;
A temperature adjusting function of locally heating the top and bottom of at least one of the found located in the vicinity are prior Symbol drying fluid in the substrate,
Pressure control means for controlling the pressure in the high-pressure vessel that heats and holds the dry fluid in a mixed state of a supercritical state and a liquid state by the temperature adjustment function;
A drying fluid discharge means for discharging the drying fluid to the high pressure vessel outer than the rinsing liquid discharge port and dry fluid outlet which is provided separately with heating by the temperature control,
A fine structure drying apparatus comprising: According to claim 8 or 9, wherein the temperature control is microstructures drying apparatus characterized by comprising setting means for setting a predetermined temperature, and control means for holding at a constant temperature.

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