JPH10118542A - Head substrate coating method and device therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To finely change a film thickness by preparing a coating liq. controlled in a prescribed concn. by mixing a prescribed amount of a dilute soln. to a base liq. having a standard concn. of the coating liq. in a chamber and executing a coating while supplying the coating liq. in the chamber to a coating liq. tank. SOLUTION: The coating liq. supplied to the coating liq. tank 12 is stored in the chamber 30. The coating liq. is controlled to the prescribed concn. by mixing the mother liq. having the standard concn. with the dilute soln. An agitator 32 is provided at the bottom of the chamber 30, and the weight of the chamber 30 is measured by a weight sensor 34. The weight change due to supplying separately the liq. (base liq. and dilute soln.) to the chamber 30 is detected by the weight sensor 34, and the liq supply is measured based on the weight change. The coating liq. in the chamber 30 is supplied to the coating liq. tank 12 by opening a liq. sending valve 38 in a state where the inside of the chamber 30 is pressurized by a pressure pump 36. In this way, the film thickness is changed without changing the circumferential speed ratio of a mirrored bar to a nip roller.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for coating a hard substrate, which is used for manufacturing a liquid crystal display panel or the like using a glass substrate and which applies a coating liquid such as a photoresist to a hard substrate in a thin and uniform manner. It is about.

[0002]

2. Description of the Related Art In a manufacturing process of a liquid crystal plate, there is a process of applying a coating liquid such as a photoresist to a thin and uniform thickness on a hard substrate such as a glass substrate. For example, in the production of a color liquid crystal plate, a transparent electrode is formed on a glass substrate in advance,
After uniformly applying a red color mosaic liquid having the function of a photoresist, the color mosaic corresponding to the red color is cured by exposure, and an excess liquid is removed to form a red color mosaic. . The same processing is repeated for other colors such as green and blue. When a coating liquid to be a photoresist is applied as described above, the liquid needs to be strictly controlled to have a uniform thickness (for example, about 1 μ ± 3%) and to be applied thinly. This is because if the thickness of the coating is non-uniform, the light transmittance becomes uneven, which leads to a deterioration in quality.

Conventionally, a spin coater has been used for this coating. In this spin coater, a coating liquid is dropped near a rotation center of a rotated substrate, and the liquid is applied by scattering using a centrifugal force. However, in the method using the spin coater, not only the time and labor efficiency for replacing the substrate are deteriorated, but also the amount of the liquid scattered and discarded increases. For this reason, there was a problem that the cost was increased.

In view of this, it has been considered to use an apparatus for coating a substrate between a pair of upper and lower rollers disposed horizontally. In this device, the lower part of the micro rod bar, which is the lower roller, is immersed in the coating solution, and the substrate is sandwiched between the micro rod bar and the nip roller located above the micro rod bar. It is to be applied.

Here, the micro rod bar is formed by winding a thin metal wire in close contact with the surface of a metal rod having a circular cross section, and applies a liquid by utilizing a capillary phenomenon caused by a groove between the metal wires.

[0006]

In this coating method, when the same coating liquid is used, the coating film thickness is almost uniquely determined by the micro rod bar. Therefore, it is necessary to replace the micro rod bar in order to change the film thickness. However, the film thickness obtained in this case is stepwise, and there is a problem that it is not possible to meet the demand to change the film thickness very slightly.

For example, since the diameter of a metal wire wound around a metal rod is usually only available at intervals of 5 μm or 10 μm, it is not possible to obtain a film thickness that changes at intervals of 5 μm or less (for example, at intervals of 2 μm). In addition, if a metal wire having an arbitrary diameter is specially made, it is possible to obtain a desired film thickness. However, manufacturing a special metal wire requires a great deal of labor and time.

It is also possible to change the film thickness by changing the peripheral speed ratio between the nip roller and the micro rod bar. However, in this case, friction occurs between the hard substrate and the micro rod bar, and the hard substrate and the micro rod bar are damaged, which is not practically desirable.

[0009]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned circumstances, and does not change a peripheral speed ratio between a nip roller and a micro rod bar. It is an object of the present invention to provide a method of applying a hard substrate, which can change the film thickness minutely without preparing.

It is a second object of the present invention to provide a hard substrate coating apparatus used directly for carrying out this method.

[0011]

According to the present invention, a first object is to provide a hard substrate between a micro rod bar whose lower part is immersed in a coating solution tank and a nip roller facing above the micro rod bar. In a hard substrate coating method of applying a coating liquid to the lower surface of the hard substrate by horizontally sandwiching and sending,
A predetermined amount of a diluent is mixed with a mother liquor having a standard concentration of a coating solution, a coating solution adjusted to a predetermined concentration is prepared in a chamber, and coating is performed while supplying the coating solution in the chamber to a coating solution tank. And a hard substrate coating method.

Here, the mixing amount A ₁ of the diluent is A ₁ = B (t / (1−t) when the film thickness is set to 1 (= 100%) as a standard and the thickness is reduced by t × 100%. ), (Where B is the weight of mother liquor in the chamber). When replenishing the chamber with mother liquor and diluent when N sheets are applied, the mother liquor is b = NC (1-t) and the diluent is A ₂ = B (t
/ (1-t)) may be supplemented. Here, C is the amount of application per substrate. Since the diluent partially evaporates during the coating, it may be added to the replenishing amount A ₂ seeking the evaporation loss in the experiment.

A second object of the present invention is to hold a hard substrate horizontally between a micro rod bar whose lower part is immersed in a coating solution tank and a nip roller facing above the micro rod bar. In a hard substrate coating apparatus that applies a coating liquid to the lower surface of the hard substrate by feeding, a chamber that stores the coating liquid diluted to a predetermined concentration, and a liquid amount sensor that measures the amount of the coating liquid that is stored in the chamber. A mother liquor supply system for supplying a standard concentration mother liquor to the chamber, a diluent supply system for supplying a diluent to the chamber, and a coating liquid supply system for supplying a coating liquid in the chamber to a coating liquid tank; A circulating pump for circulating the coating solution in the coating solution tank, calculating supply amounts of the mother liquor and the diluting solution based on the coating film thickness and supplying them to the chamber to generate a coating solution of a predetermined concentration and Rare Hard substrate coating apparatus, characterized in that the the coating solution and a control unit for controlling the whole is supplied to the coating solution tank is accomplished by.

The circulating pump may circulate only the liquid in the coating liquid tank. In this case, the liquid level of the coating liquid tank is monitored, and the liquid level falls below the reference level. Sometimes, the application liquid supply system is operated to supply the liquid. The circulation pump may circulate between the coating solution tank and the chamber. The liquid level sensor can be composed of a weight sensor that measures the weight of the chamber.In this case, the supply amount of the mother liquor or diluent can be obtained from the change in the chamber weight when the mother liquor and diluent are separately supplied to the chamber. it can.

[0015]

FIG. 1 is an overall layout view of an embodiment of the present invention, FIG. 2 is a perspective view of a main part thereof, FIG. 3 is a control system diagram, and FIG. 4 is a flow chart of operation.

In FIGS. 1 and 2, reference numeral 10 denotes a glass substrate used for a color filter of a liquid crystal plate, which serves as a hard substrate. The glass substrate 10 has a width of, for example, 300 to 7
It is 00 mm, 400-900 mm in length and 0.7 mm in thickness.

Reference numeral 12 denotes a coating solution tank, and 14 denotes a micro rod bar. The micro rod bar 14 is formed by winding a thin metal wire tightly around the surface of a rod having a circular cross section, and applies a liquid by utilizing the capillary phenomenon caused by a groove between the metal wires. The micro rod bar 14 is driven by a motor while being mounted on a backup material 16 provided in the coating liquid tank 12.

The liquid level of the coating liquid 18 is controlled to be constant so that the lower part of the micro rod bar 14 is sufficiently immersed. The outer diameter (diameter) of the micro rod bar 14 is about 6
１２12 mm. A nip roller 20 is rotatably held above the micro rod bar 14 while maintaining a predetermined gap.

The glass substrate 10 is conveyed from the left side in FIGS. 1 and 2 with its left and right edges placed on conveyance rollers, and its front edge enters between the micro rod bar 14 and the nip roller 20. Thereafter, the liquid is fed to the right side at a constant speed by the rotation of the nip roller 20 and the micro rod bar 14, and the liquid is applied to the lower surface of the glass substrate 10 by the micro rod bar 14 during that time.

In FIGS. 1 and 2, reference numeral 22 denotes a transport roller, which contacts only the lower surfaces of both right and left edges of the glass substrate 10. The transport roller 22 is driven by a drive mechanism housed in a case 24 shown in FIG. 2, and transports the glass substrate 10 at a constant speed.

The coating liquid tank 12 is long in a direction perpendicular to the direction of transport of the substrate 10, and a new liquid is supplied from a liquid supply pipe to the coating liquid tank, and the coating liquid is discharged from a drain port. The liquid level of the coating liquid is monitored by a liquid level sensor 26 shown in FIG. 3, and is constantly controlled.

The micro rod bar 14 is held horizontally so that its upper part is exposed from the liquid. The intermediate portion of the micro rod bar 14 is supported from below by the backup member 16 shown in FIG. The backup member 16 is made of a hard synthetic resin having excellent slidability, and a semicircular groove formed on the upper surface thereof along the longitudinal direction abuts against the micro rod bar 14 from below, and the micro rod bar 14 To prevent deflection.

One end (the end on the rear side in FIG. 1) of the micro rod bar 14 projects rearward from the coating solution tank 12, and this projecting end is connected to an electric motor (not shown) by a detachable joint. The rotation of the electric motor is also transmitted to the transport roller 22 so that the feed speed of the glass substrate 10 is equal to the transport speed of the transport roller 22.
The surface of the nip roller 20 is made of conductive rubber, and is held so as to apply a predetermined clamping force to the glass substrate 10 with the glass substrate 10 sandwiched between the nip roller 20 and the micro rod bar 14.

In FIG. 3, reference numeral 30 denotes a chamber which stores a coating liquid to be supplied to the coating liquid tank 12. The coating liquid is adjusted to a predetermined concentration by mixing a mother liquor of a standard concentration and a diluting liquid in the chamber 30. A stirrer 32 is attached to the bottom of the chamber 30, and the weight of the chamber 30 can be measured by a weight sensor 34. Weight sensor 34
Is to detect a change in weight caused by separately supplying liquids (mother liquor and diluent) to the chamber 30, and measure the supply liquid amount from the change in weight.

The chamber 30 is made airtight, and the coating liquid therein is supplied to the coating liquid tank 12 by a coating liquid supply system 40 formed by a pressure pump 36 for pressurizing the inside of the chamber 30 and an electromagnetic liquid supply valve 38. Sent. That is, while the inside of the chamber 30 is pressurized by the pressurizing pump 36, the application liquid is opened from the chamber 30 by opening the liquid supply valve 38.
Can be sent to

In the coating liquid tank 12, the liquid level is monitored by the liquid level sensor 26. When the liquid level exceeds a predetermined liquid level, the liquid flows to the chamber 30 via the overflow passage 42.
The coating liquid in the coating liquid tank 14 is supplied with an electromagnetic drain valve 44.
Can be discharged to the drainage bottle 46.

A mother liquor supply system 50 includes an airtight mother liquor tank 52 containing a standard concentration mother liquor, and a mother liquor tank 5.
2 has a pressure pump 54 for pressurizing the inside, and an electromagnetic liquid supply valve 56 provided in a passage for guiding the mother liquor from the mother liquor tank 52 to the chamber 30. Therefore, the mother liquor can be sent from the mother liquor tank 52 into the chamber 30 by opening the liquid sending valve 56.

Reference numeral 60 denotes a diluting liquid supply system, which has a diluting liquid tank 62 for storing the diluting liquid, and liquid feeding pumps 64 and 66 for guiding the diluting liquid in the tank 62 to the chamber 30. The liquid sending pump 64 supplies a diluting liquid to make the coating liquid in the chamber 30 have a predetermined concentration. In addition, the liquid feed pump 66 replenishes an amount of the diluting liquid corresponding to the amount of evaporation in order to correct a change in the concentration of the coating liquid due to the evaporation of the diluting liquid.

Numeral 70 denotes a circulation pump for generating a quiet and constant flow of the coating solution in the coating solution tank 14 to prevent the stagnation of the coating solution and prevent the concentration distribution from becoming uneven. It is. 72 is a control unit. The control unit 72 controls the supply amounts of the mother liquor and the diluent to the chamber 30 to generate a coating liquid having a concentration for obtaining a set coating film thickness,
It performs overall control including each valve and pump.

The controller 72 calculates the supply amounts of the mother liquor and the diluent as follows. First, a film thickness when a mother liquor having a standard concentration is applied using the microrod bar 12 is set to 1 (that is, 100%) as a standard film thickness. It is assumed that the mother liquor is diluted to reduce the film thickness by t × 100%.

First, in a state in which only the mother liquor having a weight B (gram) is put into the chamber 30, the solid content concentration (%) of the mother liquor is 100 K (%), and the total weight of the solid component is KB (gram).
Can be obtained by

On the other hand, when the film thickness is reduced by t × 100%,
The concentration of the solid component in the chamber 30 is K (1-t) × 100%
What should I do? The weight of the diluent supplied at this time is A
₁ (gram), the liquid weight in the chamber 30 is (B
+ A ₁ ) (grams). Therefore, the total weight of the solid component when this diluent is mixed is K (1-t) (B + A ₁ ), which is the total weight K of the solid component only of the mother liquor before dilution.
Should be equal to B.

Therefore, KB = K (1-t) (B + A ₁ )
From this, A ₁ = B (t / (1−t)) is obtained. This equation is hereinafter referred to as (a). By the control unit 72 the operation calculates a supply amount A ₁ of the feed amount B and the diluent in the mother liquor.
The following table summarizes the above relationships.

[0034]

[Table 1]

Next, consider the case where the mother liquor and the diluent are refilled into the chamber 30 when N substrates are applied. Assuming that the coating amount (gram) per substrate is C, the consumption of the solid component at the end of coating N substrates is K
Since it is (1-t), NC * K (1-t). Since the weight b of the mother liquor required to replenish this consumption is bK, bK = NC × K (1-t). Therefore b
= NC (1-t) to determine the amount b of mother liquor to be replenished.

At this time, the weight A _{2 of the} diluent to be replenished can be calculated by using the above equation (a), A ₂ = b {t / (1-t)} =
NCt. Note Knowing the evaporation amount a ₂ dilutions in experiment during which the replenishing amount of the diluent becomes A ₂ + a _2.

[0037]

[Operation] The control unit 72 determines the amount B of the mother liquor, the amount A _{1 of the} diluent, and the replenishment amounts b, A ₂ and a ₂ in this manner.
Each part is controlled as shown in FIG. That is, first, the pump 54
Pressurizes the inside of the mother liquor tank 52 while supplying the mother liquor to the chamber 30 by opening the valve 56 (FIG. 4, step 10).
0). During this time, the weight sensor 34 confirms that the weight of the chamber 30 increases by the supply amount B (step 10).
2). When the supply amount reaches B, the valve 56 is closed to stop supplying the mother liquor (step 104).

On the other hand, the desired coating film thickness is input from a keyboard (not shown) or the like (step 106). As described above, this film thickness is expressed as (1-t) × 100%, where the standard film thickness is 100%. The control unit 72 starts the dilution pump 64 (Step 108) and performs dilution (Step 110). Chamber 3 while supplying diluent
0 is monitored by the weight sensor 34 (step 11).
2).

[0039] Stop the dilution pump 64 supply amount of the diluent is A _1, and the end dilution (Sutepu 114). Next, the stirrer 32 is started to uniformly stir the liquid in the chamber 30 (step 116). The coating liquid supply system 40 is operated while stirring the liquid in the chamber 30, and
0 is supplied to the coating liquid tank 12 (step 11).
8). That is, the pressure in the chamber 30 is increased by the pump 36, and the valve 38 is opened.

The liquid level of the coating liquid tank 12 is determined by the liquid level sensor 2.
6, when the liquid level reaches a predetermined level (step 120), the supply of the coating liquid is stopped (step 12).
2). Then, the circulation pump 70 is started, and the coating liquid tank 1 is started.
A gentle flow is generated in the inside 2 to prevent stagnation of the liquid and an uneven portion of the liquid concentration (step 124).
To supply the coating liquid in the chamber 30 to the coating liquid tank 12 until the coating liquid reaches a predetermined liquid level (step 11).
8). In this state, the application to the glass substrate 10 is started (step 126). That is, the micro rod bar 14, the nip roller 20, and the transport roller 22 shown in FIGS. 1 and 2 are rotated at a predetermined speed, and the glass substrate 10 is fed and applied to the lower surface thereof.

While the application of the glass substrate 10 is continued, the liquid level sensor 26 constantly monitors the liquid level (step 12).
8) When the liquid level falls below the specified level, the circulating pump 70 is stopped and the application is interrupted (step 130). Then, the coating liquid may be replenished from the chamber 30 to the coating liquid tank 12. In this embodiment, at this time, the weight of the chamber 30 is measured to determine whether the amount of the coating liquid remaining in the chamber 30 is sufficient ( Step 132). If there is enough coating liquid in the chamber 30, the operation of steps 118 to 124 sends the coating liquid to the coating liquid tank 12 until the liquid level reaches a predetermined level.

If the amount of liquid in the chamber 30 is equal to or less than the specified amount (step 132), the agitator 32 is stopped (step 134), and the mother liquor and diluent are supplied to the chamber 30 by the operations of steps 100 to 114. Supply. The supply amount at this time is determined based on the number N of the substrates 10 applied as described above. That is, b = NC × (1-
t) supplied, diluent _{a 1 = b {t / (} 1-t)} and supplies.

When the evaporation amount a _{2 of the} diluent is obtained, the evaporation amount a ₂ is also replenished at the same time. That is, A ₂ + a ₂ may be supplemented by the pump 66. Since evaporation a ₂ is intended to correct the amount of evaporation from the coating liquid tank, thus may be supplied directly to the coating liquid tank a ₂ in a different pump.

That is, the supply amount of the diluent to the chamber 30 is A _{1 for} the mother liquor B and the mother liquor b
And a ₂ for. The replenishment solvent a ₂ for evaporation correction is supplied constantly into the circulation of the direct application liquid chamber in the pump 66. The supply of the replenishing solvent may be performed by either of the pumps, or the pump 66 may be shared with the pump 64, and one of the pumps 66 may be omitted and only the pump 64 may be used.

[0045]

FIG. 5 is a control system diagram of another embodiment. In this embodiment, the circulation pump 70 </ b> A circulates the coating liquid through a circulation path including the coating liquid tank 12 and the chamber 30.

That is, the coating liquid supply system 40 sends the coating liquid to the coating liquid tank 12 up to a prescribed liquid level, and thereafter the circulating pump 70A sends the coating liquid from the chamber 30 to the coating liquid tank 1
Send to 2. The overflow passage 42 is provided in the coating liquid tank 12.
Keep the liquid level constant. In FIG. 5, the same portions as those in FIG. 3 are denoted by the same reference numerals, and the description thereof will not be repeated.

[0047]

As described above, according to the first aspect of the present invention, a coating solution adjusted to a predetermined concentration by diluting a mother solution having a standard concentration with a predetermined amount of a diluting solution is prepared in a chamber, and the coating solution is applied from the chamber. Since the liquid is supplied to the liquid tank, the coating film thickness can be changed without changing the peripheral speed ratio between the micro rod bar and the nip roller and without changing the micro rod bar. This eliminates the need for the metal wire wound around the micro rod bar to have a special diameter.

In this case, the mixing amount A ₁ of the diluting liquid is set as follows.
_{A 1 = B {t / (} 1-t)}, can be calculated by (where B is the weight of the mother liquor) (claim 2). When the mother liquor and the diluent are replenished after N sheets have been applied, the mother liquor is b = NC (1-
t) (where C is the weight of the solids consumed in one application) and the diluent may be replenished by A ₂ = b {t / (1-t)} (claim 3). The replenishing amount A ₂ dilutions may be added to seek by experiment evaporation amount a ₂ dilutions (claim 4).

According to the fifth aspect of the present invention, there is provided a hard substrate coating apparatus directly used for carrying out this method. The coating liquid tank may be provided with a liquid level sensor, and the circulation pump may circulate the coating liquid in the coating liquid tank while maintaining the liquid level at a constant level. The circulation pump may circulate between the chamber and the coating solution tank (claim 7). The liquid amount sensor that detects the amount of liquid supplied to the chamber is formed by a weight sensor that detects the weight of the chamber, and the mother liquor and diluent are separately supplied, and the supply amount of each liquid is detected from the weight change at that time. (Claim 8).

[Brief description of the drawings]

FIG. 1 is an overall layout diagram of an embodiment of the present invention.

FIG. 2 is an enlarged perspective view of the application section.

FIG. 3 is a control system diagram

FIG. 4 is a flowchart of the operation.

FIG. 5 is a control system diagram of another embodiment.

[Explanation of symbols]

 Reference Signs List 10 glass substrate (hard substrate) 12 coating liquid tank 14 micro rod bar 20 nip roller 22 transport roller 26 liquid level sensor 30 chamber 32 stirrer 34 weight sensor as liquid quantity sensor 40 coating liquid supply system 50 mother liquor supply system 60 diluent Supply system 70, 70A Circulation pump 72 Control unit

[Procedure amendment]

[Submission date] March 18, 1997

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0034

[Correction method] Change

[Correction contents]

[0034]

[Table 1]

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Toshiyuki Fujikura 1005 Koizono, Ayase City, Kanagawa Prefecture Inside Fuji Mike Logigraphics Corporation (72) Inventor Masafumi Ozaki 1005 Koizono, Ayase City, Kanagawa Prefecture Fuji Mike Logigraphics Corporation (72) Inventor Masao Otsu 1005 Koizono, Ayase City, Kanagawa Prefecture Fuji Micrographix Co., Ltd.

Claims (8)

[Claims] The hard substrate is horizontally fed between a micro rod bar whose lower part is immersed in a coating solution tank and a nip roller opposed to and disposed above the micro rod bar. In a method of applying a coating liquid on the lower surface of a hard substrate, a coating liquid adjusted to a predetermined concentration by mixing a predetermined amount of a diluting liquid with a mother liquid having a standard concentration of the coating liquid is prepared in a chamber, and the coating liquid in the chamber is A hard substrate coating method, wherein the coating is performed while supplying the liquid to a coating liquid tank. 2. The mixing amount A ₁ of the diluting liquid is expressed by the following formula: A ₁ = B (t / t)
2. The method for applying a hard substrate according to claim 1, wherein (1-t)) (where B is the weight of the mother liquor in the chamber). 3. When the mother liquor and the diluent are replenished to the chamber during the coating, the amount of mother liquor to be replenished every N coatings is represented by the formula:
b = NC (1-t), and the replenishment amount A of the diluent
_{2, wherein: A 2 = b (t /} (1-t)) Hardness substrate coating method according to claim 2 which is calculated by. 4. The replenishing amount A ₂ dilutions, hard substrate coating method according to claim 3 which adds the replenishment amount corresponding to the evaporation amount calculated by experiments. 5. A hard substrate is horizontally sandwiched and sent between a micro rod bar whose lower part is immersed in a coating liquid tank and a nip roller facing above said micro rod bar. A hard substrate coating apparatus for applying a coating liquid on the lower surface of a chamber, a chamber for storing the coating liquid diluted to a predetermined concentration, a liquid amount sensor for measuring the amount of the coating liquid stored in the chamber, and a standard concentration for the chamber. A mother liquor supply system for supplying a mother liquor, a diluent supply system for supplying a diluent to the chamber, a coating liquid supply system for supplying a coating liquid in the chamber to a coating liquid tank, and a coating liquid in the coating liquid tank. A circulating pump for circulating the liquid; calculating a supply amount of the mother liquor and the diluting liquid based on the coating film thickness; supplying them to the chamber to generate a coating liquid having a predetermined concentration; Tank And a controller for controlling the whole of the hard substrate and controlling the whole. 6. A level sensor for detecting a liquid level in a coating liquid tank, wherein the coating liquid supply system maintains the liquid level at a predetermined liquid level detected by the level sensor, and a circulation pump is provided in the coating liquid tank. The hard substrate coating apparatus according to claim 5, wherein the coating liquid is circulated between the inside and the inside. 7. The hard substrate coating apparatus according to claim 5, wherein the circulation pump circulates the coating liquid between the chamber and the coating liquid tank. 8. The liquid amount sensor is a weight sensor for measuring the weight of the chamber, and detects a liquid amount of the mother liquor and the diluent separately supplied to the chamber based on a change in the measurement result of the weight sensor. 1. A method for applying a hard substrate.