JP2005163079A - Thin film forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To form a thin film excellent in the uniformity of film thickness on a planar substrate surface in a thin film forming apparatus using a spray thermal decomposition method. <P>SOLUTION: At the time when the surface 3a of a previously heated planar substrate 3 is sprayed with the droplets 2 of a raw material solution comprising a thin film raw material and an organic solvent from a raw material solution spraying means 4 to form a thin film on the surface 3a, the planar substrate 3 is heated by a substrate heating means 6 so as to have a temperature distribution corresponding to the amount of the droplets of the raw material solution to be sprayed per unit area in the surface 3a of the planar substrate 3. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a thin film forming apparatus.

  As a technique for forming a thin film on the surface of a plate substrate such as a glass substrate, a spray pyrolysis method has been conventionally known (for example, see Non-Patent Document 1). In the spray pyrolysis method, first, a raw material solution is prepared by dissolving a thin film raw material in an organic solvent. When this raw material solution is mixed with the compressed gas and sprayed toward the heated plate-like substrate, the mist-like droplets of the raw material solution are supplied to the surface of the plate-like substrate. The droplets of the raw material solution are heated on the surface of the plate-like substrate, and the organic solvent that is the liquid phase is evaporated and vaporized, whereby the thin-film raw material that is the solid phase is deposited, and the deposited thin-film material is deposited on the surface of the plate-like substrate. It grows by adhering to form a thin film. The spray pyrolysis method enables film formation even when the substrate heating temperature is lowered compared to other chemical thin film formation methods such as atmospheric pressure chemical vapor deposition (CVD), and the film formation rate is high. The device has a simple structure and low maintenance frequency.

  Various thin film forming apparatuses based on the spray pyrolysis method have been proposed (see, for example, Patent Document 1 and Patent Document 2). FIG. 8 is a perspective side view schematically showing a configuration of a conventional thin film forming apparatus 100. The thin film forming apparatus 100 controls a spraying means 103 for spraying raw material solution droplets 102 by spraying a raw material solution containing a thin film raw material and an organic solvent toward the plate-like substrate 101, and a spray amount of the raw material solution. A spray control means 104 for heating, a heating means 105 for heating the plate-like substrate 101, and an exhaust means 106 for exhausting an organic solvent vapor evaporating from the raw material solution to the outside by heating. . Further, the spraying means 103 is a plate-like substrate obtained by mixing the raw material solution storage means 107 for storing the raw material solution, the gas storage means 108 for storing the carrier gas mixed in the raw material solution, and the raw material solution and the carrier gas. And a spray nozzle 109 for spraying on the surface of 101. Compressed air or the like is used as the carrier gas. The spray control means 104 includes a solenoid valve 110 that controls on / off of the spray nozzle 109 and a valve control means 111 that controls opening and closing of the spray nozzle 109 by the solenoid valve 110. The heating unit 105 includes a heater 112 for heating the plate-like substrate 101 and a stage 113 for holding the plate-like substrate 101 and the heater 112. The stage 113 holding the plate-like substrate 101 and the heater 112 is conveyed directly below the spray nozzle 109 by a conveying means such as a belt conveyor (not shown).

  According to the thin film forming apparatus 100, first, the raw material solution is supplied from the raw material solution storage unit 107 and the compressed gas is supplied from the gas storage unit 108 to the spray nozzle 109. The raw material solution and the compressed gas are mixed in the spray nozzle 109, sprayed onto the surface 101 a of the plate-like substrate 101 held by the stage 113, and the raw material solution droplets 102 are supplied by spraying. Since the plate-like substrate 101 is heated to a desired temperature by the heater 112, the organic solvent evaporates and vaporizes from the sprayed droplets 102 of the raw material solution, the thin film forming raw material is deposited, and the surface 101a of the plate-like substrate 101 is deposited. A thin film is formed. The organic solvent vapor is exhausted to the outside by the exhaust means 106. By repeating this spraying operation a plurality of times, a thin film having a desired film thickness can be formed.

  As described above, in the thin film forming apparatus 100 based on the spray pyrolysis method, the spray nozzle 109 is disposed substantially directly above the central portion of the plate-like substrate 101 that is conveyed from the outside and held at a predetermined position.

  By the way, when the solution is sprayed from the nozzle toward the center part of the flat plate-like object, the spray amount per unit area of the solution is large in the center part of the plate-like object and at the end part due to the structural characteristics of the nozzle. Less.

  Therefore, when a thin film is formed on the surface 101 a of the plate-like substrate 101 using the conventional thin film forming apparatus 100, the central portion of the plate-like substrate 101 has a surface 101 a due to the position and structural characteristics of the spray nozzle 109. On the other hand, a thin film swelled in the vertical direction is formed, and a thin film having a thickness smaller than that of the central thin film is formed at the end of the plate-like substrate 101. It is very difficult to form a thin film having a uniform thickness over the entire surface 101a of the plate-like substrate 101 using the thin film forming apparatus 100. The thin film forming apparatus 100 is not particularly suitable for forming an antireflection film that requires a uniform thin film.

  After the thin film is formed around the center of the plate-like substrate 101, the plate-like substrate 101 is moved to a position where its end is directly below the spray nozzle 109, and the raw material solution is sprayed again to form a thin film film. A method of adjusting the thickness is also conceivable. However, such a method causes an increase in the number of steps and an increase in raw material cost, and the uniformity of the obtained thin film is not sufficiently satisfactory.

Japanese Patent Laid-Open No. 10-130097 JP 2001-26885 A Functional Materials March 2000 Vol. 20 No. 3 (p.5-7)

  An object of the present invention is to provide a thin film forming apparatus capable of forming a thin film having a uniform film thickness on the entire surface of a plate-like substrate.

The present invention includes a raw material solution spraying means for spraying a mixture of a raw material solution containing a thin film raw material and an organic solvent and a carrier gas, and spraying the liquidity of the raw material solution onto the surface of the plate-like substrate, and spraying of droplets of the raw material solution In a thin film forming apparatus including spray control means for controlling the amount, substrate heating means for heating the plate-like substrate, and exhaust means for exhausting gas generated mainly by evaporation of the carrier gas and the organic solvent to the outside,
The substrate heating means
Heating means for heating the plate-like substrate;
Temperature detecting means for detecting the temperature distribution of the plate substrate;
A heating control means for controlling the operation of the heating means based on the detection result of the temperature detection means so that the plate-like substrate has a predetermined temperature distribution according to the spray amount of the raw material solution per unit area on the plate-like substrate. When,
A thin film forming apparatus comprising at least a plate-like substrate and holding means for holding heating means.

The thin film forming apparatus of the present invention is
The substrate heating means
Heating means for heating the plate-like substrate;
Heat conduction means for conducting heat generated by the heating means to the plate-like substrate;
Temperature detecting means for detecting the temperature distribution of the plate substrate;
Based on the detection result of the temperature detection means, a heating control means for controlling the operation of the heating means so as to have a predetermined temperature distribution according to the spray amount of the raw material solution per unit area in the plate-like substrate,
It is characterized by comprising at least a plate-like substrate, a heating means and a holding means for holding a heat conduction means.

Furthermore, the thin film forming apparatus of the present invention is
The heating means heats the plate-like substrate so as to have a temperature distribution substantially inversely proportional to the spray amount per unit area of the raw material solution on the plate-like substrate surface.

Furthermore, the thin film forming apparatus of the present invention is
The heating means includes a heat source having a substantially annular shape on a plan view.

Furthermore, the thin film forming apparatus of the present invention is
A plurality of substantially annular heat sources are arranged on concentric circles.

  According to the present invention, a raw material solution spraying means for spraying a mixture of a raw material solution containing a thin film raw material and an organic solvent and a carrier gas and spraying the liquidity of the raw material solution onto the surface of the plate substrate, and a droplet of the raw material solution In a thin film forming apparatus comprising: a spray control means for controlling the amount of spraying; a substrate heating means for heating the plate-like substrate; and an exhaust means for exhausting gas generated mainly by evaporation of the carrier gas and the organic solvent to the outside. The substrate heating means is a heating means for heating the plate-like substrate, a temperature detection means for detecting the temperature distribution of the plate-like substrate, and the raw material solution per unit area in the plate-like substrate based on the detection result by the temperature detection means. A thin film including heating control means for controlling the operation of the heating means so that the plate-like substrate has a predetermined temperature distribution according to the spray amount, and holding means for holding at least the plate-like substrate and the heating means Forming apparatus is provided.

  By using such a thin film forming apparatus of the present invention, even if the spraying means of the raw material solution is a spray nozzle, the film thickness can be increased over the entire surface of the plate-like substrate without being affected by the structural characteristics of the spray nozzle. A uniform thin film can be formed. Therefore, the thin film forming apparatus of the present invention can be suitably used for forming a thin film in general, particularly an antireflection film.

  According to the research of the present inventors, it has been found that in the spray pyrolysis method, the thin film formation rate on the heated plate-like substrate surface depends on the temperature of the plate-like substrate surface. That is, the temperature of the plate-like substrate surface and the thin film formation speed are directly proportional, and as the temperature increases, the thin film formation speed increases and the amount of thin film formed increases. In a conventional thin film forming apparatus, a heating means such as a heater is incorporated and fixed in a certain direction at the center of the surface of a stage holding a plate-like substrate. When the plate-like substrate is placed on this, the temperature is higher at the central portion near the heating means of the plate-like substrate, and at the edge of the plate-like substrate, the temperature is relatively far away from the heating means, and heat radiation is likely to occur. , The temperature is lower than the central part. Therefore, in the conventional thin film forming apparatus, it is very difficult to control the entire surface of the plate-like substrate at substantially the same temperature. In addition to this, the spray amount of the raw material solution is locally determined from the structural characteristics of the spray means. Due to the difference, the thin film formed on the plate-like substrate has a mountain shape in which the central portion rises in a direction perpendicular to the surface of the plate-like substrate and the film thickness at the end portion is thin. In contrast, in the present invention, a thin film having a uniform thickness is formed on the entire surface of the plate substrate by heating the plate substrate so that the temperature distribution corresponding to the spray amount of the raw material solution is provided. can do.

  Further, according to the present invention, in the above-described substrate heating means, a heat conduction means is provided between the plate-like substrate and the heating means, and the plate-like substrate is not directly heated by the heating means but via the heat conduction means. By heating in this manner, temperature control over the entire surface of the plate-like substrate can be realized more easily. Therefore, a thin film with a uniform film thickness can be formed more easily.

  Further, according to the present invention, when heating the plate substrate so as to have a temperature distribution corresponding to the spray amount per unit area of the raw material solution on the plate substrate surface, heating is performed so as to be approximately inversely proportional to the spray amount. Thus, a thin film with further improved film thickness uniformity can be formed. More specifically, for example, if the plate substrate is heated such that the temperature of the central portion where the spray amount of the plate substrate is large is relatively lower than the temperature of the end portion of the plate substrate where the spray amount is small. Good.

  Further, according to the present invention, in the heating means described above, by using a substantially annular heat source, the temperature of the end of the plate-like substrate where the spray amount of the raw material solution is relatively small, the spray amount is relatively large. Temperature control to be higher than the temperature at the central portion of the plate-like substrate can be performed accurately and easily. Furthermore, the annular heat source is not structurally complicated and has a simple structure, so that it can be realized at a low cost and is industrially advantageous.

  Further, according to the present invention, in the above-mentioned heating means, by arranging a plurality of substantially annular heat sources on concentric circles, the temperature of the plate-like substrate can be more precisely controlled, so that the thin film formed The thickness can be made more uniform.

  FIG. 1 is a perspective side view schematically showing a configuration of a thin film forming apparatus 1 according to a first embodiment of the present invention. FIG. 2 is a perspective view schematically showing the external appearance of the thin film forming apparatus 1 shown in FIG. 1 and the substrate transport means provided attached thereto.

  The thin film forming apparatus 1 includes a raw material solution spraying means 4 that sprays a mixture of a raw material solution containing a thin film raw material and an organic solvent and a carrier gas, and sprays droplets 2 of the raw material solution onto the surface 3a of the plate-like substrate 3, and a raw material Spray control means 5 for controlling the spray amount of the droplet 2 of the solution, substrate heating means 6 for heating the plate-like substrate 3, carrier gas, vapor of organic solvent evaporated from the raw material solution by heating, etc. And an exhaust means 7 for exhausting to the outside.

  The raw material solution spraying means 4 mixes the raw material solution storage means 8 for storing the raw material solution, the carrier gas storage means 9 for storing the carrier gas, the raw material solution and the carrier gas, and the resulting mixture to the plate-like substrate 3. And spraying means 10 for spraying the raw material solution droplets 2 onto the surface 3 a of the plate-like substrate 3.

  The thin film raw material contained in the raw material solution stored in the raw material solution storage means 8 is not particularly limited, and a known thin film raw material can be used. For example, when forming a titanium thin film, tetra-iso-propoxide titanium Further, titanium alkoxides such as tetra-n-propoxy titanium, tetra-n-butoxy titanium, and tetra-iso-butoxy titanium can be used. As the raw material solution storage means 8, those commonly used in this field can be used. For example, a container made of a material that is inert to the raw material solution and does not dissolve impurities in the raw material solution can be used.

  Since the carrier gas is compressed into a high-pressure gas, a general pressure-resistant container made of a material that has pressure resistance and does not give impurities to the carrier gas is used for the carrier gas storage means 9. As the carrier gas, air, nitrogen gas, helium gas, argon gas, etc. can be used. However, nitrogen gas, helium gas, argon gas and other thin-film raw materials, and gas inert to the plate substrate are preferable. Is particularly preferred. The flow rate of the carrier gas can be appropriately selected from a wide range according to the type of the thin film raw material and organic solvent contained in the raw material solution, the type of the carrier gas itself, the structure and shape of the injection means 10, etc. In consideration of further improving the thickness uniformity, the flow rate may be selected so that the diameter of the droplet 2 of the raw material solution is about several tens to 100 μm.

  Various nozzles, such as a spray nozzle, are used for the injection means 10, for example. A commercial item can be used for a spray nozzle, for example, brand name STA-6R (made by Fuso Seiki Co., Ltd.) etc. are mentioned. The injection of the mixture of the raw material solution and the carrier gas can be performed a plurality of times as necessary. At this time, the interval between the spray and the next spray is such that the temperature of the surface 3a of the plate-like substrate 3 is lowered by the spray, the droplet 2 of the raw material solution is heated on the surface 3a of the plate-like substrate 3, and the carrier gas, In order to prevent the subsequent thin film formation from being affected by the gas generated by the evaporation of the organic solvent in the droplet 2, it is sufficient to consider exhausting these gases to the outside by the exhaust means 7. It is preferable to leave a gap.

  In the raw material solution spraying means 4, a raw material solution obtained by previously dissolving a thin film raw material in an appropriate organic solvent is stored in the raw material solution storage means 8, and a highly compressed carrier gas is stored in the carrier gas storage means 9. The raw material solution and the carrier gas are supplied to the spraying means 10 from the storage means 8 and 9. The raw material solution and carrier gas supplied to the spraying means 10 are mixed there, and the resulting mixture is sprayed from the spraying means 10 toward the surface 3 a of the plate-like substrate 3. Thereby, the droplet 2 of the raw material solution is sprayed on the surface 3 a of the plate-like substrate 3. The droplet 2 of the raw material solution undergoes a decomposition reaction on the surface 3 a of the plate-like substrate 3, and the organic solvent evaporates and gasifies to change from a liquid phase to a solid phase, and on the surface 3 a of the plate-like substrate 3. A thin film is formed.

  The spray control means 5 opens and closes the spray means 10 and controls the solenoid valve 11 for controlling on / off of the injection of the mixture of the raw material solution and the carrier gas by the spray means 10 and the operation of the solenoid valve 11 to thereby control the raw material solution. And a valve control device 12 for controlling injection of a mixture of the carrier gas and the carrier gas. In the spray control means 5, when the plate-like substrate 3 is transported into the apparatus 1 by the substrate transport means 27 described later and placed at a predetermined position, the valve control device 12 issues a command to the solenoid valve 11, and the solenoid valve 11 opens the spraying means 10, and a mixture of the raw material solution and the carrier gas is sprayed toward the surface 3 a of the plate-like substrate 3. Then, after a thin film having a desired film thickness is formed on the surface 3a of the plate-like substrate 3, the valve control device 12 issues a command to the solenoid valve 11, and the solenoid valve 11 closes the spraying means 10, and the raw material solution and Injection of the mixture with the carrier gas stops.

  The substrate heating means 6 includes a heating means 13 for heating the plate-like substrate 3, a heat conduction means 14 for conducting heat generated by the heating means 13 to the plate-like substrate 3, and a temperature distribution on the surface 3 a of the plate-like substrate 3. Based on the temperature detection means 15 to be detected and the detection result of the temperature detection means 15, the plate-like substrate 3 has a predetermined temperature distribution according to the spray amount of the raw material solution per unit area on the plate-like substrate 3. The temperature control means 16 for controlling the operation of the heating means 13 and the holding means 17 for holding at least the plate-like substrate 3 and the heating means 13 are configured.

  FIG. 3A and FIG. 3B are a perspective plan view and a perspective side view schematically showing the configuration of the heating means 13, the heat conduction means 14, and the holding means 17, respectively.

  The heating means 13 is disposed in a recess formed in the surface 17 a of the holding means 17. The heating means 13 is formed in a substantially annular shape and includes a plurality of heating members 13a, 13b, 13c, 13d provided concentrically, and is laid on the bottom surface of the recess. The heating members 13a, 13b, 13c, and 13d are independently connected to the temperature control means 16, and based on the detection result of the temperature detection means 15 that detects the temperature distribution of the surface 3a of the plate-like substrate 3, the temperature is controlled. The temperature is separately managed by the control means. As a result, the surface 3a of the plate-like substrate 3 can have a concentric temperature distribution. For the heating members 13a, 13b, 13c, and 13d, for example, a heater made of a resistor such as a nichrome wire is used.

  The heat conducting means 14 is provided in the upper layer of the heating means 13 in a recess formed on the surface 17a of the holding means 17, and a plurality of surfaces 14a for contacting and holding the plate-like substrate 3 are sucked and held on the surface 14a. Suction holes 18, 19, 20, 21, and 22 are formed, and these are connected to the suction pipe 24 inside the heat conduction means 14, and the suction pipe 24 is in a portion where the heat conduction means 14 and the holding means 17 are in contact with each other. Are connected to a pipe 23 provided on the holding means 17 side, and the pipe 23 is further connected to a vacuum suction device (not shown). Since the plate-like substrate 3 is sucked and held by the heat conducting means 14 through the suction holes 18, 19, 20, 21, and 22, the plate-like substrate 3 is removed from the surface 14a of the heat conducting means 14 during conveyance and formation of the thin film. It is prevented from falling off, and heat can be reliably transferred from the heat conducting means 14 to the plate-like substrate 3. As the heat conduction means 14, the suction holes 18, 19, 20, 21, 22 and the suction pipe 24 can be easily formed, and the heat generated from the heating means 13 can be efficiently conducted to a plate-like substrate (not shown), In addition, those made of a material capable of eliminating the diffusion of impurities into the plate-like substrate at a high rate are preferable, and examples thereof include a carbon susceptor.

  The temperature detecting means 15 is arranged on the surface layer of the heat conducting means 14 and the holding means 17, and detects the temperature distribution on the surface 3 a of the plate substrate 3, and the temperature control means 16 using the signal from the sensor 25 as a detection result. And a detector 26 that transmits the signal. The temperature distribution information on the surface 3 a of the plate-like substrate 3 detected by the sensor 25 is transmitted to the temperature control means 16 via the detector 26.

  The temperature control means 16 is electrically connected to the temperature detection means 15 and the heating members 13a, 13b, 13c, and 13d. The temperature control means 16 receives the temperature distribution information of the plate-like substrate 3 from the temperature detection means 15, and controls the heating members 13a, 13b, 13c, 13d separately based on the information, and the temperature distribution of the plate-like substrate 3 Can be adjusted to a predetermined temperature distribution according to the spray amount of the raw material solution per unit area on the plate-like substrate 3. If the heating members 13a, 13b, 13c, and 13d are heaters, the temperature control means 16 adjusts the current value flowing through each heater based on the measurement result of the temperature detection means 15, and the heating temperature is controlled for each heater. The As a result, the variation in temperature distribution on the plate-like substrate surface 3a is controlled within a predetermined range, and the thickness of the formed thin film is adjusted to be substantially uniform.

  The holding means 17 holds the heating means 13 and the heat conduction means 14 in a recess formed in the surface 17a, and a pipe 23 is provided on one side surface of the recess in contact with the heat conduction means 14. One end of the pipe 23 is connected to a suction pipe 24 formed in the heat conducting means 14, and the other end is connected to a vacuum suction device (not shown).

  According to the substrate heating means 6 having such a configuration, the plate-like substrate 3 placed on the surface 14 a of the heat conducting means 14 is attached to the suction holes 18, 19, 20, 21 and 22, and the temperature distribution of the surface thereof is changed to the spray amount of the raw material solution per unit area on the plate-like substrate 3 by the heating member 13, the heat conduction means 14, the temperature detection means 15 and the temperature control means 16. Accordingly, the temperature distribution is adjusted to a predetermined temperature distribution.

  The exhaust means 7 is a gas generated by the carrier gas and raw material solution droplets 2 sprayed toward the plate-like substrate 3 being heated on the surface 3a of the plate-like substrate 3, and the organic solvent contained therein evaporating. Is provided to exhaust the air to the outside. A general exhaust device can be used as the exhaust means 7. Although the exhaust means 7 may always be operated, the air flow generated by the exhaust may affect the spray amount of the raw material solution droplets 2 and is preferably stopped during the spray operation.

  Further, as shown in FIG. 2, substrate transport means 27 for transporting the plate-like substrate 3 into the thin film forming apparatus 1 is provided along with the thin film forming apparatus 1. The plate-like substrate 3 is placed on the substrate carrying means 27 while being placed on the substrate heating means 6. For the substrate transfer means 27, for example, a belt conveyor is used. The plate-like substrate 3 is moved in the direction of the arrow 28 by the substrate transfer means 27 and transferred into the thin film forming apparatus 1, and after the thin film is formed, it is discharged again by the substrate transfer means 27.

  FIG. 4 is a graph showing the spray amount of the raw material solution droplet 2 per unit area in each part of the surface 3a of the plate-like substrate 3 when a spray nozzle is used as the spraying means 10. As is apparent from FIG. 2, the spray amount at the central portion of the plate-like substrate 3 located almost immediately below the ejection means 10 is b1, and the spray amount gradually decreases from the central portion toward the end portion, and the plate shape. At the end of the substrate 3, it becomes b2. The spray amount of the raw material solution droplets 2 is the kind and concentration of the thin film raw material contained in the raw material solution, the kind of organic solvent, the flow rate of the carrier gas, the structure of the spraying means 10, and the surface 3 a of the plate-like substrate 3 from the spraying means 10. However, the amount of spray at the center of the plate-like substrate 3 is always larger than the amount of spray at the end. Therefore, after determining the value of each condition affecting the spray amount, it is necessary to perform spraying, measure the spray amount of each part on the surface 3a of the plate-like substrate 3, and determine the spray amount in advance. Become.

  FIG. 5 is a graph showing the relationship between the temperature of the surface 3 a of the plate substrate 3 and the thin film formation speed on the surface 3 a of the plate substrate 3. As apparent from FIG. 5, when the temperature of the surface 3a of the plate-like substrate 3 is t1, the thin film formation rate is a1, and when the temperature of the surface 3a of the plate-like substrate 3 is t2, the thin film formation rate is a2. It is. And t1> t2 and a1> a2. That is, the surface temperature of the plate-like substrate and the thickness of the thin film to be formed are in a substantially direct relationship. Therefore, by adjusting the temperature distribution of the surface 3a of the plate-like substrate 3 so as to be inversely proportional to the predetermined amount of droplets of the raw material solution per unit area of the plate-like substrate 3, the film thickness becomes more uniform. A thin film can be formed. In FIG. 5, the film thickness of the thin film formed at each substrate temperature is used as an index of the thin film formation speed, and the relative thin film formation speed is shown. In addition, the values of t1, t2, a1, and a2 vary depending on various conditions such as the type and concentration of the thin film raw material in the raw material solution, the type of organic solvent, the spray amount of droplets of the raw material solution, and the temperature of the plate substrate. After these conditions are set to a certain value, spraying is actually performed and obtained in advance.

  FIG. 6 is a graph showing the temperature distribution on the surface 3 a of the plate-like substrate 3 when the plate-like substrate 3 is heated by the substrate heating means 6. In the graph of FIG. 6, the vertical axis represents the substrate surface temperature, and the horizontal axis represents the distance from the substrate central portion to both ends relative to the central portion of the substrate. A spray nozzle (not shown) is provided substantially directly above the center of the substrate, and a mixture of the raw material solution and the carrier gas is injected. From FIG. 6, the surface temperature of the plate-like substrate 3 heated by the substrate heating means 6 is T, and the surface temperature gradually increases as it approaches the both ends from the center, and reaches T + ΔT at both ends. It can be seen that the surface temperature increases.

ΔT shown in FIG. 6 represents the spray amount (b1) and the spray amount (b2) at the center of the plate-like substrate 3 shown in FIG. 4, and the surface 3a of the plate-like substrate 3 shown in FIG. Based on the temperature and the thickness of the thin film to be formed (film thickness a1 at the surface temperature t1, film thickness a2 at the surface temperature t2), it can be determined by the following equation.
ΔT = [(a1 / r) −a1] × [(T2−T1) / (a2−a1)]
[Where r = b1 / b2. ]

  Therefore, ΔT is determined based on the above formula, and heating is performed by the substrate heating means 6 so that the surface temperature of the central portion of the plate-like substrate 3 is T and the surface temperature of the end portion of the plate-like substrate 3 is T + ΔT. For example, a thin film having a uniform thickness can be formed. The heating between the center portion and the end portion of the plate-like substrate 3 may be complemented as appropriate, for example, linear interpolation may be performed.

  In the above description, although the optimum surface temperature is determined at the central portion and the end portion of the plate-like substrate 3, an intermediate portion between the central portion and the end portion is obtained in order to obtain a thin film having a more uniform film thickness. However, the optimum surface temperature may be calculated by a similar method to control heating.

  Below, based on FIG. 1 and FIG. 2, the operation | movement of the thin film formation to the surface 3a of the plate-shaped board | substrate 3 by the thin film forming apparatus 1 is demonstrated. First, in the thin film forming apparatus 1, the amount of the raw material solution droplet 2 sprayed by the raw material solution spraying means 4 is determined, and the relationship between the surface temperature of the surface 3a of the plate-like substrate 3 and the film thickness of the thin film to be formed is obtained. A surface temperature distribution optimum for forming a thin film having a uniform film thickness is set on the surface 3 a of the plate-like substrate 3. Next, the plate-like substrate 3 placed on the substrate heating means 6 is carried into the thin film forming apparatus 1 by the substrate carrying means 25 so that the central portion of the plate-like substrate 3 comes directly under the raw material solution spraying means 4. The position of the plate-like substrate 3 is adjusted, the plate-like substrate 3 is fixed on the substrate heating means 6 by vacuum suction, and heated so as to have a predetermined surface temperature distribution. A droplet of the raw material solution is sprayed from the raw material solution spraying means 4 onto the heated plate-like substrate 3 to form a thin film on the surface 3 a of the plate-like substrate 3. The plate-like substrate 3 on which the thin film is formed is discharged to the outside by the substrate transfer means 25.

  In the present embodiment, as shown in FIG. 5, in the substrate heating means 6, the heating means 13 that generates heat for heating the plate-like substrate 3 is formed in a substantially annular shape and provided concentrically. Although it is configured to include a plurality of heating members 13a, 13b, 13c, and 13d, it is not limited thereto, and may be configured from one substantially annular heating member. 7A and 7B are a perspective plan view and a perspective side view schematically showing the configuration of another form of substrate heating means 29 in the thin film forming apparatus of the present invention. Since the substrate heating means 29 has the same configuration as the substrate heating means 6 except for the heating means 30, the same reference numerals are assigned and description thereof is omitted. Further, illustration of the suction holes and suction pipes formed in the heat conduction means 14, the temperature detection means 15, the temperature control means 16 and the pipes provided in the holding means 17 is omitted. The substrate heating means 29 is characterized in that the heating means 30 is composed of one substantially annular heating member. The heating means 30 is disposed below the outer peripheral portion of the plate-like substrate 3 placed on the heat conducting means 14 and mainly heats the end portion of the plate-like substrate 3. As a result, on the surface 3a of the plate-like substrate 3, a temperature distribution is realized in which the temperature at the center is low and the temperature at the end is high. Such a substrate heating means 29 can be suitably used for forming a thin film that does not require a precise film thickness uniformity as that of an antireflection film, for example. The substrate heating means 29 is industrially advantageous because the structure is further simplified than the substrate heating means 6.

  In the present embodiment, a belt conveyor is used for the substrate transfer means 25 provided in association with the thin film forming apparatus 1, but other known moving methods may be used, such as a walking beam method. .

  By using the thin film forming apparatus of the present invention, it is possible to easily form thin films such as a titanium oxide film, a tin oxide film, a tin sulfide, an indium oxide film, and an ITO film.

It is a see-through | perspective side view which shows typically the structure of the thin film forming apparatus which is the 1st Embodiment of this invention. It is a perspective view which shows roughly the external appearance of the thin film forming apparatus shown in FIG. 1, and the board | substrate conveyance means provided with it. FIG. 2 is a perspective plan view and a perspective side view schematically showing configurations of a heating means, a heat conduction means, and a holding means in the thin film forming apparatus shown in FIG. 1. It is a graph which shows the spraying quantity of the raw material solution per unit area in each part of the plate-shaped substrate surface. It is a graph which shows the relationship between the surface temperature in a plate-shaped board | substrate, and a thin film formation speed. It is a graph which shows the temperature distribution of the plate-shaped substrate surface when a plate-shaped substrate is heated in the thin film forming apparatus shown in FIG. It is the perspective top view and perspective side view which show schematically the structure of the board | substrate heating means of another form in the thin film forming apparatus of this invention. It is a see-through | perspective side view which shows the structure of the conventional thin film forming apparatus typically.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Thin film forming apparatus 2 Liquid suitable for raw material solution 3 Plate substrate 3a Surface of plate substrate 4 Raw material solution spraying means 5 Spray control means 6, 29 Substrate heating means 7 Exhaust means 8 Raw material solution storage means 9 Carrier gas storage means 10 Spray Means 11 Solenoid valve 11
12 valve control device 13, 30 heating means 13a, 13b, 13c, 13d heating member 14 heat conduction means 14a heat conduction means surface 15 temperature detection means 16 temperature control means 17 holding means 17a holding means surface 18, 19, 20, 21, 22 Suction hole 23 Pipe 24 Suction tube 25 Sensor 26 Detector 27 Substrate transport means 28 Arrow

Claims (5)

A raw material solution spraying means for spraying a mixture of a raw material solution containing a thin film raw material and an organic solvent and a carrier gas to spray droplets of the raw material solution onto the surface of the plate-like substrate, and a spray amount of the droplets of the raw material solution are controlled. In a thin film forming apparatus including spray control means, substrate heating means for heating a plate-like substrate, and exhaust means for exhausting gas generated mainly by evaporation of carrier gas and organic solvent to the outside,
The substrate heating means
Heating means for heating the plate-like substrate;
Temperature detecting means for detecting the temperature distribution of the plate substrate;
A heating control means for controlling the operation of the heating means based on the detection result of the temperature detection means so that the plate-like substrate has a predetermined temperature distribution according to the spray amount of the raw material solution per unit area on the plate-like substrate. When,
A thin film forming apparatus comprising at least a plate-like substrate and holding means for holding heating means. The substrate heating means
Heating means for heating the plate-like substrate;
Heat conduction means for conducting heat generated by the heating means to the plate-like substrate;
Temperature detecting means for detecting the temperature distribution of the plate substrate;
Based on the detection result of the temperature detection means, a heating control means for controlling the operation of the heating means so as to have a predetermined temperature distribution according to the spray amount of the raw material solution per unit area in the plate-like substrate,
The thin film forming apparatus according to claim 1, comprising at least a plate-like substrate, a heating unit, and a holding unit that holds the heat conduction unit. The heating means
The thin film forming apparatus according to claim 1 or 2, wherein the plate substrate is heated so as to have a temperature distribution that is substantially inversely proportional to the spray amount per unit area of the raw material solution on the surface of the plate substrate. The heating means
The thin film forming apparatus according to claim 1, comprising a heat source having a substantially annular shape on a plan view. The heat source with a generally annular shape is
The thin film forming apparatus according to claim 4, wherein a plurality of concentric circles are arranged.

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