JP2006150175A - Thin film forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem that since the larger the surface area of a substrate is, the larger the area of an opening part of a mist supply part is, when the flow rate of a carrier gas is not increased, the flow rate of a discharge to a mist supply part is not increased and discharge quantity is unstable, when a coating liquid is made particulate and applied to the substrate. <P>SOLUTION: The thin film forming apparatus is provided with a mist producing chamber provided with a two-fluid nozzle, a mist supply part for applying mist produced in the mist producing chamber on the substrate, a driving stage provided with a moving mechanism which is opposed to the slit opening of the mist supply part, holds the substrate with a prescribed interval and moves in a horizontal direction, a liquid sending/recovering mechanism for recovering the coating liquid collected on the bottom of the mist producing chamber and sending and recovering the coating liquid to be recycled, a pressure reducing valve between the mist supply part and the mist producing chamber and an assistant pressure gas supply part for keeping the pressure in the mist producing chamber to a prescribed value. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a thin film forming apparatus for forming a uniform thin film by atomizing a solution and discharging it onto a substrate.

  As a method of uniformly forming a thin film on a large-area substrate in the manufacturing process of semiconductors, liquid crystals, PDPs, etc., a method of forming a thin film by atomizing by an inkjet method, a spray method, an ultrasonic method, etc., and spraying this on the substrate There is. Patent Document 1 discloses a coating apparatus configured to generate a mist from a mist generating chamber using a nozzle or an ultrasonic oscillator, and to discharge the mist from a mist supply unit onto a substrate by a carrier gas flow. .

  In Patent Document 2, fine particles discharged from a nozzle are discharged into a flow regulating member, guided to the lower part of the separation container by the flow straightening member, and thereafter, the fine particles floating while passing through the fine particle sorting plate in the separation container are upper part of the separation container. An ultrafine particle generator configured to be discharged from a discharge portion provided in the above is disclosed.

Patent No. 28895671

Japanese Patent Laid-Open No. 2003-10741

  In the method of Patent Document 1, the larger the substrate, the larger the opening area of the mist supply unit. Therefore, unless the carrier gas flow rate is increased, the flow rate of discharge supplied to the mist supply unit does not increase. The discharge amount was unstable. However, if the flow rate of the carrier gas is increased, even a large particle size is transported to the mist supply unit, so that it has been difficult to form a uniform thin film.

  Further, in the method of the cited document 2, the ultrafine particles floating from the separation chamber are discharged from the nozzle. However, depending on the internal pressure in the separation chamber, the discharge amount is also uneven, and a uniform thin film with high accuracy is formed. Has a problem. Further, it is described that particles having a large particle diameter are sent from the bottom of the separation chamber to the liquid reservoir and reused. However, there is no disclosure regarding what kind of processing is performed for reuse. That is, if the liquid generated in the normal separation chamber is reused as it is, there is a high possibility that the formation of the film will be adversely affected.

  Accordingly, an object of the present invention is to provide a thin film forming head capable of forming a uniform thin film at once on a large-area substrate.

  In order to achieve the above object, the present invention is directed to a mist generating chamber provided with a two-fluid nozzle, a mist supply unit for applying the mist generated in the mist generating chamber on a substrate, and a slit opening of the mist supply unit. A drive stage equipped with a moving mechanism that moves the substrate in a horizontal direction while holding the substrate at a predetermined interval, and a coating liquid collected at the bottom of the mist generating chamber is collected, and a coating liquid to be reused is fed and collected. A liquid / recovery mechanism is provided, a pressure reducing valve is provided between the mist supply section and the mist generation chamber, and an auxiliary pressure gas supply section for maintaining the pressure in the mist generation chamber at a predetermined value is provided.

  As described below, the coating liquid is atomized using a nozzle, and a pressure reducing valve is provided between the mist supply section and the mist generating chamber, so that the flow rate of the carrier gas is not increased and the discharge is performed according to the opening of the pressure reducing valve. The flow rate of the mist can be increased and stable discharge can be performed from the mist supply unit. Further, it is possible to generate a uniform mist state in the mist generating chamber. Due to the above effects, a uniform thin film can be formed on the substrate.

  Embodiments of the present invention will be described below with reference to the drawings.

  First, the overall structure of the present invention will be described with reference to FIG. FIG. 1 shows a schematic view of a thin film forming apparatus of the present invention.

  As shown in FIG. 1, a mist supply pipe 16 that supplies mist to the mist supply unit 31 is connected to the upper end of the mist generating chamber 14. An internal pressure adjusting pressure reducing valve 1 is provided in the middle of the mist supply pipe 16. The drive stage 53 is located below the mist supply unit 31, and the substrate 51 is placed on the upper surface of the drive stage 53. A throw-away area 54 is fixed to the side surface of the drive stage 53. The nozzle 11 is fixed at an appropriate position on the opposite side of the upper center of the mist generating chamber 14 or the mounting position of the mist supply pipe 16. The nozzle 11 is a two-fluid nozzle provided with a gas supply port for supplying gas and a liquid supply port for supplying liquid to be applied. A valve 43, a pressure sensor 44, a pressure reducing valve 45, and a pressurized gas (air or nitrogen) supply source 52 are arranged in this order in a pipeline connected to the gas supply port to the nozzle 11.

  Further, a valve 41, a pressure sensor 42, a liquid feeding / recovery mechanism 22 are sequentially connected to a pipeline connected to the liquid supply port of the nozzle 11. The liquid feeding / recovery mechanism 22 is a system that feeds with a gas sent from the pressurized gas supply source 52 via the pressure reducing valve 48. Further, the liquid feeding and recovery mechanism 22 is connected to the bottom of the mist generating chamber 14 via a valve 15 and a pump 21 by a pipe line. The solution accumulated in the mist generating chamber 14 is sent to the liquid feeding and recovery mechanism 22 by opening the valve 15 and operating the pump 21. The mist generating chamber 14 is provided with an internal pressure measuring sensor 12 for measuring the indoor pressure. Further, the mist generating chamber 14 is provided with a pipe line for supplying gas pressure directly and adjusting the pressure in the mist generating chamber 14 (for supplying auxiliary pressurized gas). 13, a pressure sensor 46, a pressure reducing valve 47, and a pressurized gas supply source 52 are provided in this order.

  Next, the operation will be described with reference to FIGS.

  FIG. 2 shows the relationship between the flow rate variation and the internal pressure of the mist generating chamber 14 in the upper stage, and the gas pressure, liquid pressure, and auxiliary pressurized gas pressure (pressure by the carrier gas) from filling to discharge end in the lower stage. FIG. 3 shows an operation flow from filling the mist generation chamber 14 to the mist generation chamber 14, discarding discharge, and starting discharge.

  As an example, the operation will be described on the assumption that the ink is discharged onto a substrate 51 having a size of □ 730 × 920. As shown in the flow of FIG. 3, the optimum particle diameter to be discharged onto the substrate 51 is determined in advance in consideration of the viscosity of the solution to be a thin film, the surface tension, the state of the substrate surface, the desired film thickness, and the like. After that, the gas pressure and hydraulic pressure that must be supplied to the nozzle 11 are determined. In this embodiment, the gas pressure and hydraulic pressure supplied to the nozzle 11 were set to 0.1 (MPa) and 0.3 (MPa).

  In addition, the mist supply part 31 becomes a structure provided with the slit-shaped opening long in the left-right direction, as shown in FIG.2 (b). For this reason, it is necessary to prevent the discharge amount from being varied in the left-right direction. However, as shown in the upper part of FIG. 2, when the internal pressure of the mist generating chamber 14 (with the valve 13 opened) is low, the flow rate discharged from the mist supply unit 31 varies greatly in the left-right direction of the discharge port. The reason is considered that when the internal pressure of the mist generating chamber 14 is low, the discharge flow rate in the mist supply unit 31 does not increase, and the fluid resistance portion in the mist supply unit 31 does not function as a resistance. Therefore, in order to suppress variation in the discharge amount in the left-right direction of the flow rate discharged from the mist supply unit 31, the internal pressure of the mist generation chamber 14 is set to be 0.01 (MPa) (300).

  Next, the internal pressure adjusting pressure reducing valve 1, the valve 13, the valve 41, and the valve 43 are closed to make the mist generating chamber 14 in a sealed state (301). Next, the discharge condition is set to the pressure reducing valve 45, and the set value of the pressure reducing valve 48 is substituted with a gas pressure of 0.3 (MPa) and a hydraulic pressure of 0.1 (MPa) (302). Next, gas and liquid are supplied to the nozzle 11 by opening the valve 41 and the valve 43 (303). Thereby, fine particles are discharged from the nozzle 11 into the mist generating chamber 14. At this time, the inside of the mist generating chamber 14 is pressurized as shown in the lower diagram of FIG. 2 because the valves 1, 13, and 15 are closed and sealed. Since the gas pressure and hydraulic pressure conditions determined by setting the discharge conditions are conditions under atmospheric pressure, the pressure is reduced according to the increase in the reading of the internal pressure in the mist generating chamber (the reading of the internal pressure measurement sensor 12) as shown in FIG. It is necessary to change the set values of the valve 45 and the pressure reducing valve 48 (304).

  A filling time ΔT1 in which fine particles are uniformly filled in the mist generation chamber 14 by discharging under the same discharge conditions is obtained in advance. When the filling time ΔT1 has elapsed, the internal pressure adjusting pressure reducing valve 1 is opened (305). When the internal pressure adjusting pressure reducing valve 1 is opened, the mist supply unit 31 has moved the drive stage 53 so as to be positioned on the discarding area 54 provided in the drive stage 53.

  By opening the pressure reducing valve 1 for adjusting the internal pressure, the mist supply unit 31 starts discarding discharge, and the internal pressure of the mist generating chamber 14 drops with the start of discarding discharge (306). In order to correct this drop in internal pressure, the pressure is adjusted by the pressure reducing valve 47 and the pressure sensor 46 confirms that the pressure is the predetermined pressure (the set value of the internal pressure (the same pressure from 0.01 to 0.5 MPa)). The valve 13 is opened and supplied as auxiliary pressurized gas, and the internal pressure is gradually increased (307), so that the reading value of the internal pressure measurement sensor 12 becomes equal to the set value 0.01 (MPa) of the internal pressure. Even at this time, the supply of the pressure of the auxiliary pressurized gas is continued, but if the auxiliary pressurized gas is supplied too rapidly, there is a possibility that even a large particle size is conveyed to the mist supply unit 31. Therefore, even if the auxiliary pressurized gas is supplied, the internal pressure in the mist generating chamber 14 may not be fully increased to 0.01 (MPa) as shown in the lower diagram of Fig. 2. At this time, the internal pressure adjusting pressure reducing valve Mist generation by adjusting the opening of 1 It is also possible to increase the pressure in the chamber 14 (308), and during this time, the discarding discharge is continued in the discarding area 54. The internal pressure in the mist generating chamber 14 is set to 0.01 (MPa). When the readings of the internal pressure measurement sensor 12 become equal, the disposal discharge is finished (309).

  Thereafter, the drive stage 53 is moved in the direction of the arrow (in the direction of the lower left arrow in FIG. 1), and discharge onto the substrate 51 is started. When the drive stage 53 is moved to the final end of the substrate 51, the discharge is finished. In that case, after the internal pressure adjusting pressure reducing valve 1 and the valve 13 are closed, the valve 41 and the valve 43 are closed to stop the production of fine particles discharged from the nozzle 11.

  Next, the detail of the collection | recovery liquid feeding mechanism shown in FIG. 1 is demonstrated using FIG. FIG. 4 shows a schematic diagram of the recovery and liquid feeding mechanism shown in FIG.

  As shown in FIG. 4, in order to supply the liquid to be applied to the liquid supply port of the nozzle 11 of FIG. 1, a first liquid feed tank 222 with a stirring and cooling jacket for accumulating liquid (hereinafter referred to as the first liquid feed tank). Is provided. A temperature raising unit 227 is provided in the pipe line from the first liquid feeding tank 222 so that the liquid can be supplied to the nozzle 11 at a predetermined temperature. Further, it is determined whether the liquid collected at the bottom of the mist generating chamber 14 should be a waste liquid or a liquid to be reused. Recovered in the attached second liquid feeding tank 221 (hereinafter referred to as the second liquid feeding tank). For this purpose, the liquid content from the pump 21 is measured for the water content by the viscosity measuring unit 211, and it is determined whether to discard or reuse the liquid from the result, and what is discarded is discarded via the three-way valve 229. The one to be reused is heated from the three-way valve 229 by the temperature raising unit 217, the dust is removed by the filter 213, defoamed by the gas-liquid separation unit 214 provided with the gas-liquid separation membrane, and secondly sent. It is configured to send to the liquid tank 221. The gas-liquid separation unit 214 is connected to a vacuum pump 220 for discharging the gas separated by defoaming.

  In addition, a solution 1 liquid supply tank 215, a solution 2 liquid supply tank 216, and a stock solution liquid supply tank 231 are connected to the second liquid supply tank 221 by a pipe line. The reason for providing two types of solution feeding tanks in this way is that, in this embodiment, two types of solutions are mixed and used as a coating solution. In that case, if one of the solutions is highly volatile and mixed in advance, the solution of one of them will volatilize and the mixing ratio will change, so that the two types of solution feed tanks can be mixed immediately before use. Is provided. Further, the concentration of the stock solution feeding tank 231 can be increased by sending the stock solution from the stock solution feeding tank 231 to the second feeding tank 221 when the heating means 217 is not provided or when the concentration becomes too low due to the solutions 1 and 2. Is to adjust. Needless to say, when a solution that does not cause a large change in the mixing ratio is used, this solution feeding tank may be used as one. Further, in order to supply liquid from the second liquid supply tank 221 to the first liquid supply tank 222, a pipe line provided with a two-way valve 230 is provided. In order to supply air pressure for supplying the liquid from the second liquid supply tank 221 to the first liquid supply tank 222, a pipe line is provided from the pressurized gas supply source 52 via the pressure reducing valve 48 and the three-way valve 228. . A pipe for supplying a gas pressure for supplying a liquid from the first liquid supply tank 222 to the nozzle 11 is also provided from the three-way valve 228.

  Further, a return pipe for returning the solution to the second liquid feeding tank 221 is provided at a predetermined height position of the first liquid feeding tank 222. That is, the installation position of the second liquid supply tank 221 is provided at a lower position than the installation position of the first liquid supply tank. A pipe line is provided between the cooling jackets provided in the first liquid feeding tank 222 and the second liquid feeding tank 221 so that the cooling water circulates through a water cooling pump.

  Furthermore, viscosity measuring units 224 and 225 are provided in the first liquid feeding tank 222 and the second liquid feeding tank, respectively, in order to measure the water content of the liquid in the tank.

  Next, the operation will be described with reference to FIGS. Since the liquid recovery method varies slightly depending on the material used, the operation will be described assuming an alignment film material as an example.

  The fine particles adhering to the inner wall surface or the like of the mist generating chamber 14 in FIG. However, this liquid is contaminated with dust, gas, moisture absorption, etc., and it is difficult to reuse it as it is. Therefore, the valve 15 is opened, and the recovered liquid in the mist generating chamber 14 is supplied to the liquid supply and recovery mechanism 22 by the pump 21. However, in this embodiment, only nitrogen gas (N2) is used as the gas source. For this reason, basically, it is considered that there is no moisture absorption with respect to the collected liquid accumulated in the mist generating chamber 14.

  Next, the recovered liquid in the mist generating chamber 14 is passed through the viscosity measurement unit 211, where the water content is measured, and it is determined whether or not it can be reused based on the measurement result. Regarding the measurement of the moisture content, in the case of the alignment film material, the moisture content can be specified from the change in viscosity due to the fact that the moisture absorption is sufficiently larger than the volatilization amount of the solvent for a short time. If the water content is within 5% (normally, the stock solution is about 0.2%), it is determined that it can be reused. However, in the case of 5% or more, the three-way valve 229 is opened to the waste liquid tank 212 side and discarded as waste liquid. However, the value that the water content is within 5% varies depending on the type of the alignment film material, and is merely an example in this embodiment.

  For the reusable solution, the heating temperature and the heating time are determined so that the water content is within 0.2%, and the temperature raising unit 217 is operated. Then, the three-way valve 229 is opened to the second liquid feeding tank 221 side, and passes through the temperature raising unit 217 for dehumidification. The liquid that has passed through the temperature raising unit 217 is sent to the filter 213, where dust is removed. Next, air bubbles are removed by passing through the gas-liquid separator 214. In forming a film due to moisture content, dust, and bubbles, the film uniformity, dry state, pinhole ratio, and the like are affected. Therefore, it is necessary to perform the above treatment. By passing the filter 213 (having a hole diameter of 1 μm or less), dust or the like of 1 μm or more can be removed. The recovered liquid that has been subjected to moisture removal, dust removal, and bubble removal is fed to the second liquid feeding tank 221.

  Finally, the viscosity value of the stock solution in the first liquid feeding tank 222 (value of the viscosity measuring unit 224) and the viscosity value of the recovered liquid in the second liquid feeding tank 221 (value of the viscosity measuring unit 225) are compared to determine the solution. An appropriate amount of the solution is fed from the 1 liquid feeding tank 215 and the solution 2 liquid feeding tank 216 to the second liquid feeding tank 221 to adjust the viscosity.

  When the adjustment of viscosity or the like is completed, the valve 230 is opened, the three-way valve 228 for sending pressurized gas (nitrogen gas at a predetermined pressure) is opened on the second liquid feeding tank 221 side, and the recovered liquid in the second liquid feeding tank 221 is discharged. Liquid is fed to the first liquid feeding tank 222. After the liquid feeding is finished, the three-way valve 228 is closed. In addition, since the alignment film material has an effect of preventing deterioration of the material due to moisture absorption when stored at a low temperature, the water cooling pump 226 supplies water to the second liquid supply tank 221 and the jacket portion of the first liquid supply tank 222. So that it can be maintained at a low temperature of 20 ° C. or lower. However, since there is a material temperature suitable for film formation at the time of discharge, the temperature is raised by the temperature raising unit 227 and the liquid is supplied to the nozzle 11.

  As described above, in the liquid feeding and recovery mechanism 22 of the present invention, since the temperature and viscosity of the solution to be used are adjusted and the liquid is fed to the mist generating chamber 14, fine particles for coating having a uniform diameter are generated. And a uniform film can be generated.

It is the schematic of the thin film forming apparatus of one Example of this invention. It is a figure which shows the relationship between flow volume dispersion | variation and internal pressure in the upper stage, and the relationship of each pressure from filling to completion | finish of discharge in a lower stage. It is the figure which showed the operation | movement flow of discharge. It is the schematic of a material collection | recovery and liquid feeding mechanism.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Pressure reducing valve for internal pressure adjustment, 11 ... Nozzle, 12 ... Internal pressure measurement sensor, 13 ... Valve, 14 ... Mist generating chamber, 15 ... Valve, 16 ... Mist supply pipe, 21 ... Pump, 22 ... Liquid feeding and recovery mechanism, DESCRIPTION OF SYMBOLS 31 ... Mist supply part, 41 ... Valve, 42 ... Pressure sensor, 43 ... Valve, 44 ... Pressure sensor, 45 ... Pressure reducing valve, 46 ... Pressure sensor, 47 ... Pressure reducing valve, 48 ... Pressure reducing valve, 51 ... Substrate, 52 ... Nitrogen supply source 53... Drive stage 54 54 Discarding area 211. Viscosity measuring unit 212. Waste liquid tank 213 Filter 214 214 Gas-liquid separation membrane 215 Solution 1 feed tank 216 Solution 2 Liquid feeding tank, 217 ... heating unit, 221 ... liquid feeding tank with stirring cooling jacket, 222 ... liquid feeding tank with stirring cooling jacket, 224 ... viscosity measuring unit, 225 ... viscosity measuring unit, 226 ... water Cooling pump, 227 ... heating unit, 228 ... 3-way valve, 229 ... 3-way valve.

Claims (2)

A mist generating chamber having a two-fluid nozzle, a mist supply unit for applying the mist generated in the mist generating chamber onto the substrate, and holding the substrate at a predetermined interval facing the slit opening of the mist supply unit And a drive stage equipped with a moving mechanism that moves in the horizontal direction, and a liquid feed / recovery mechanism that collects the coating liquid accumulated at the bottom of the mist generating chamber and feeds and collects the coating liquid to be reused. In thin film forming equipment,
A thin film forming apparatus comprising a pressure reducing valve between the mist supply section and a mist generation chamber, and an auxiliary pressure gas supply section for maintaining the pressure in the mist generation chamber at a predetermined value. . The thin film forming apparatus according to claim 1,
The liquid feeding / recovery mechanism measures the water content of the recovered liquid, removes water with a heating unit, removes dust, separates gas and liquid, and then increases the amount of liquid volatilized by heating. A thin film forming apparatus characterized by that.

Images