JP2005166882A - Etching method and etching device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an etching method capable of etching with good controllability without lengthening a process time, and to provide an etching device for performing the method. <P>SOLUTION: The etching method for performing etching by immersing a glass substrate W to be etched in an etching chemical liquid L previously obtains relation of a temperature increase amount of the etching chemical liquid L and an etching amount of the base substance to be etched during etching. On the basis of the relation, etching is completed at the time point when the temperature increase amount of the etching chemical liquid L reaches a prescribed value corresponding to a set etching amount. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an etching method and an etching apparatus for performing this method, and in particular, it is necessary to control the etching film thickness with high precision as in the case of thinning a glass substrate constituting a liquid crystal panel. The present invention relates to an etching method and an etching apparatus.

  In manufacturing processes of liquid crystal panels and semiconductor devices, so-called wet etching is performed in which etching is performed by immersing a substrate to be etched in an etching chemical solution. In general, in wet etching, etching proceeds by a reaction between a substrate which is a substrate to be etched and an etching reactive species. For this reason, as the etching progresses, the etching reactive species are consumed and the concentration of the etching reactive species in the etching chemical decreases, and the temperature of the etching chemical increases due to the generation of reaction heat. Such a change in the etching chemical solution causes a change in the etching rate. Further, in such wet etching, it is difficult to accurately measure the thickness of the substrate to be etched while being immersed in an etching chemical.

  For this reason, in the conventional wet etching, the etching rate is stabilized by keeping the concentration and temperature of the etching chemical solution constant, thereby obtaining the controllability of the etching amount.

  For example, in manufacturing a liquid crystal panel, etching using dilute hydrofluoric acid is performed in a glass substrate thinning process. In this case, every time a predetermined etching time elapses, a dilute hydrofluoric acid solution is newly added to stabilize the dilute hydrofluoric acid concentration, and the etching amount is controlled by managing the etching time to control the etching end point. Is detected. In this case, in order to further control the etching amount, the etching rate is grasped in the first etching, and the remaining etching time is set based on this etching rate. In some cases, the second etching is performed.

  In manufacturing a semiconductor device, etching using a phosphoric acid aqueous solution is performed for processing a laminated film of a silicon oxide film and a silicon nitride film formed over a substrate. In this case, the concentration of dissolved silicon (Si) or the like eluted in the phosphoric acid aqueous solution is detected. A method of controlling the etching amount by exchanging the etchant so that the Si concentration is within a predetermined range within a range where the etching rate of the silicon oxide film does not become too high has been proposed (for example, the following patents). Reference 1).

JP 2001-23952 A.

  However, it is very difficult to keep the concentration of the etching solution constant at all times by the method of stabilizing the etching rate by managing the etching chemical solution as described above and thereby ensuring the controllability of the etching amount. Therefore, the controllability of the etching amount has not been sufficient for controlling the etching amount within an extremely thin film thickness range.

  Even if the etching rate is grasped in the first etching as described above, and the remaining etching time is set based on this etching rate and the second etching is performed, the etching rate in the etching process is as follows. However, it is difficult to say that the controllability is sufficient. In addition, such a method also takes time and trouble due to performing etching twice, resulting in a problem that the process time becomes long.

  Accordingly, an object of the present invention is to provide an etching method capable of performing etching with good controllability without increasing the process time and an etching apparatus for performing this method.

  The etching method of the present invention for achieving such an object is an etching method in which etching is performed by immersing a substrate to be etched in an etching chemical solution. In the first method, first, a relationship between the temperature rise amount of the etching chemical during etching and the etching amount of the substrate to be etched is obtained in advance. Then, based on the obtained relationship, the etching is terminated when the temperature rise amount of the etching chemical solution reaches a predetermined value corresponding to the set etching amount. On the other hand, in the second method, first, the relationship between the change in the concentration of the reaction product generated in the etching chemical during etching and the etching amount is obtained in advance. Then, based on the obtained relationship, the etching is terminated when the concentration change of the reaction product in the etching chemical solution reaches a predetermined state corresponding to the set etching amount.

  In such a first etching method, the etching end point is detected by directly grasping the etching amount itself by terminating the etching based on the temperature rise amount of the etching chemical having a correlation with the etching amount. . In the second etching method, the etching end point is detected by directly determining the etching amount itself by terminating the etching based on the change in the concentration of the reaction product in the etching chemical having a correlation with the etching amount. Is done. Therefore, in the first method and the second method, the etching can be finished with the set desired etching amount. Note that these first method and second method may be combined.

  Moreover, the etching apparatus of this invention is an apparatus which performs the etching method mentioned above. The first apparatus includes a processing tank for performing an etching process, a temperature measuring unit for measuring the temperature of the etching chemical, and a memory for storing a relationship between the temperature increase amount of the etching chemical during etching and the etching amount of the substrate to be etched. And an etching substrate from the etching chemical solution in the processing tank when the temperature rise measured by the temperature measuring unit reaches a predetermined value corresponding to the set etching amount based on the relationship stored in the storage unit The control means which makes the state pulled up is provided.

  In such a first apparatus, the temperature rise amount of the etching chemical solution measured by the temperature measuring means is predetermined based on the relationship between the temperature rise amount of the etching chemical solution stored in the storage means and the etching amount of the substrate to be etched. When the value is reached, the etching base is pulled up from the etching chemical by the control means, and the etching is finished. For this reason, the etching is performed by the first etching method described above, in which the etching is terminated based on the temperature increase amount of the etchant having a correlation with the etching amount.

  Further, the second apparatus includes a processing tank for performing etching, a concentration measuring unit for measuring the concentration of the reaction product in the etching chemical, and a change in the concentration of the reaction product generated in the etching chemical during etching. Storage means for storing the relationship with the etching amount of the substrate to be etched, and a concentration change measured by the concentration measuring means based on the relationship stored in the storage means has reached a predetermined state corresponding to the set etching amount At the time, there is provided control means for bringing the etching substrate up from the etching chemical solution in the processing tank.

  According to such a second apparatus, the etching chemical liquid measured by the concentration measuring means based on the relationship between the change in the concentration of the reaction product in the etching chemical liquid stored in the storage means and the etching of the substrate to be etched. When the concentration change reaches a predetermined state, the etching base is pulled up from the etching chemical by the control means, and the etching is finished. For this reason, etching is performed by the above-described second etching method in which etching is terminated based on a change in the concentration of the reaction product in the etching chemical having a correlation with the etching amount. Note that the second device may be combined with the first device.

  As described above, according to the etching method of the present invention, it is possible to terminate the etching with a desired etching amount by directly grasping the etching amount itself and detecting the etching end point. Controllability can be improved. In addition, since the etching amount can be controlled in-line, no special effort is required. Therefore, even when etching an extremely thin substrate to be etched, it becomes possible to perform etching with good controllability without lengthening the process time.

  Further, according to the etching apparatus of the present invention, it is possible to automatically perform the above-described etching method for directly detecting the etching amount itself and detecting the etching end point.

  Next, embodiments of the present invention will be described in detail with reference to the drawings. In the following embodiment, an embodiment in which the present invention is applied to a process of thinning a glass substrate by wet etching using dilute hydrofluoric acid as an etching chemical in a manufacturing process of a liquid crystal panel will be described.

<Etching device>
FIG. 1 is a block diagram showing an example of an etching apparatus for performing the etching method of the present invention. The etching apparatus shown in this figure includes a processing tank 1 in which an etching process is performed. In the processing tank 1, an etching chemical solution L is stored, and a glass substrate W to be etched is accommodated in a state of being immersed in the etching chemical solution L. Further, a temperature measuring means 2 for measuring the temperature of the etching chemical liquid L in the processing tank 1, a concentration measuring means 3 for measuring the concentration of the reaction product in the etching chemical liquid L, an etching amount for detecting the end point of etching, and A storage means 4 for storing the relationship with the state of the etching chemical L, and a temperature measurement means 2, a concentration measurement means 3, and a control means 5 connected to the storage means 4 are provided.

  Among these, as shown in the enlarged sectional view of FIG. 2 (a) and the enlarged top view of FIG. 2 (b), the treatment tank 1 has two layers provided with a storage tank 1b for storing the etching chemical L in the exterior sink 1a. The storage tank 1b is configured to be covered with a cover 1c. And it is the structure accommodated in the inner storage tank 1b in the state by which about 1-60 glass substrates W are immersed in the etching chemical | medical solution L. FIG. Although illustration is omitted here, the glass substrate W is accommodated in the storage tank 1b while being supported by the carrier.

  Moreover, as shown in FIG. 1, the preparation tank 6 is connected to the processing tank 1 of such a configuration through a supply pipe 7 provided with a pump P. The preparation tank 6 is for preparing an etching chemical solution L to be supplied into the processing tank 1. For example, a pure water tank 8 and a hydrofluoric acid tank 9 are connected to such a mixing tank 6 via a mass flow meter MF, and a circulation system 10 for circulating the etching chemical L in the mixing tank 6 is provided. Yes. In addition, a thermometer 11 is arranged in the preparation tank 6 and a hydrofluoric acid concentration meter 12 is arranged in the circulation system 10 so that the temperature of the etching chemical L in the preparation tank 6 is uniformly controlled. .

  Further, a recycling tank 14 is connected to the treatment tank 1 via a drainage pipe 15. The recycle tank 14 is used for etching in the processing tank 1 to temporarily store and recycle the etching chemical L, and is connected to the preparation tank 6 by a liquid feeding system 16. The recycle liquid stored inside is transported into the preparation tank 6. The recycle tank 14 is also connected to a waste liquid system (not shown), and the deposits in the recycle tank 14 are discarded.

  As described above, the preparation tank 6 has a predetermined concentration by the pure water supplied from the pure water tank 8, the hydrofluoric acid supplied from the hydrofluoric acid tank 9, and the recycle liquid (diluted hydrofluoric acid) supplied from the recycle tank 14. Diluted hydrofluoric acid is adjusted and temperature controlled. Here, for example, dilute hydrofluoric acid having a ratio of hydrofluoric acid: pure water = 1: 1.5 to 4 (for example, about 5 wt% to 40 wt%) is adjusted as the etching chemical L. Then, the etching chemical liquid L prepared in the preparation tank 6 is supplied from the supply pipe 7 into the processing tank 1.

  And in this processing tank 1, the bubbling board 18 which ejects dry air (DA) shall be provided. Thereby, the etching chemical | medical solution L supplied in the processing tank 1 is stirred, the etching chemical | medical solution L in the processing tank 1 is maintained in a uniform state, and the etching in the processing tank 1 is stabilized.

  Next, the temperature measuring means 2 measures the temperature of the etching chemical solution L in the processing tank 1 having the above configuration. The temperature measuring means 2 is preferably arranged in the processing tank 1 so that the temperatures at a plurality of locations in the processing tank 1 are measured. For example, as shown in FIG. It shall be arranged in each part.

  And the concentration measurement means 3 measures the density | concentration of the reaction product in the etching chemical | medical solution L in the processing tank 1 of the said structure. The concentration measuring means 3 is preferably arranged in the processing tank 1 so that the concentration at a plurality of locations in the processing tank 1 is measured. For example, as shown in FIG. It shall be arranged in each part.

  Here, the concentration measuring means 3 may be any device that can measure the concentration of a predetermined reaction product eluted in the etching chemical L during etching. However, in order to obtain measurement accuracy, a reaction product with a large amount of product is generated. It is preferable to measure the concentration of.

For example, where a glass substrate W for a liquid crystal panel serving as the etching substrate, the SiO ₂ as the main component (50 to 75 _{mol%), Al 2 O 3 (} 7~25 _{mol%), B 2 O 3 (} 1 0.5-9.5 mol%), MgO (1.5-10 mol%), CaO (1.5-10 mol%), SrO (1.5-10 mol%), BaO (0-1.0). Mol%) and the like. During etching, these substances react with water and hydrofluoric acid contained in the etching chemical solution L, and various reaction products are eluted in the etching chemical solution L.

  When the glass substrate W having a mixed configuration is etched using dilute hydrofluoric acid, hydrogen fluoride (H2SiF6, hexanefluorosilicic acid) is generated as a reaction product in a relatively large amount. For this reason, as the concentration measuring means 3, a concentration meter (for example, an infrared liquid component concentration meter) for measuring the concentration of hydrogen silicofluoride is disposed in the treatment tank 1 as the concentration measuring means 3. The reaction product measured by the concentration measuring means 3 is not limited, and reactive organisms other than hydrogen silicofluoride may be measured.

  Next, the storage means 4 stores the relationship between the temperature rise amount (Td) of the etching chemical L and the etching amount (Vet) of the glass substrate W and the concentration of the reaction product in the etching chemical L in the target etching. The relationship between the change (Cd) and the etching amount (Vet) of the glass substrate W is stored. These relationships will be described in detail in the following etching method.

  The control means 5 is connected to the temperature measurement means 2, the concentration measurement means 3, and the storage means 4 described above, and includes a drive unit 5a, an input unit 5b, and a control unit 5c.

  Among these, the drive part 5a may be a mechanism which pulls up the glass substrate W from the inside of the processing tank 1 according to the instruction | indication from the control part 5c. In this case, for example, the carrier supporting the glass substrate W (not shown) is pulled up. The drive unit 5a is a mechanism that opens the drainage pipe 15 and discharges the etching chemical solution L in the processing tank 1 in accordance with an instruction from the control unit 5c, thereby pulling up the glass substrate W from the etching chemical solution L. It may be.

  The input unit 5b is a part for setting an etching amount to be an etching end point, and is configured as an external input terminal.

  The control unit 5 c is connected to the temperature measurement unit 2, the concentration measurement unit 3, and the storage unit 4. This control unit 5c is based on each relationship stored in the storage means 4 and the etching amount set by the input from the input unit 5b, and the amount of the etching chemical solution L and the reaction product in the etching chemical solution L. When the concentration change reaches a predetermined state corresponding to the set etching amount, the driving unit 5a is driven so that the glass substrate W is pulled up from the etching chemical solution L in the processing tank 1. The control procedure in the controller 5c will be described in detail in the next etching method.

<Etching method>
Hereinafter, an embodiment of an etching method using the etching apparatus will be described with reference to FIG. 1 and other drawings as needed.

  First, prior to etching an actual product, a glass substrate W similar to the actual product is etched on a trial basis under etching conditions substantially equivalent to the actual etching conditions. Here, for example, dilute hydrofluoric acid having a concentration of about 5 wt% to 40 wt% is used.

  Based on the result of this experimental etching, as shown in FIG. 3, the relationship between the temperature rise amount (Td) of the etching chemical L during this etching and the etching amount (Vet) of the glass substrate W is obtained. Keep it. Here, the etching amount (Vet) is the volume of the etched glass substrate W. The purpose here is to reduce the thickness of the glass substrate W to a predetermined thickness. Therefore, the etching amount (Vet) may be the etching film thickness (Det) removed by etching. However, the etching film thickness (Det) varies depending on the etching area of the glass substrate W that is the substrate to be etched. For this reason, if the size of the glass substrate W is the same, as shown in FIG. 4, the relationship between the temperature rise (Td) of the etching chemical L and the etching film thickness (Det) is etched at once. It may be obtained for each number of glass substrates W, that is, for each etching area.

  The vertical axis in the graphs of FIGS. 3 and 4 is the temperature rise (Td), and the temperature at which the etching is started may be any number, and the temperature increase of the etching chemical L from the time when the etching is started. It is assumed that it corresponds to. This relationship is applied regardless of the concentration of the etchant L.

  Similarly, based on the result of this experimental etching, as shown in FIG. 5, the concentration change (Cd) of the reaction product in the etching chemical L during this etching and the etching amount (Vet of the glass substrate W). ). Here, the etching amount (Vet) of the glass substrate W is the volume of the etched glass substrate W. This relationship may be the etching film thickness (Det) that is removed by etching, as in the relationship between the etching amount and the temperature increase described with reference to FIGS. Alternatively, it may be obtained for each number of glass substrates W to be etched at a time, that is, for each etching area.

  As shown in the graph of FIG. 5, the increment of the etching amount varies depending on the concentration range of the reaction product in the etching chemical L. For this reason, the relationship between the concentration change (Cd) of the reaction product and the etching amount (Vet) of the glass substrate W is obtained from the initial value when the concentration of the reaction product in the etching chemical L is 0%. I will leave it.

  Such relationships are stored in the storage unit 4 of the etching apparatus.

  After obtaining the above relationships, the actual product is etched as follows.

  First, an etching film thickness is obtained from the initial film thickness of the glass substrate W before etching and the target film thickness of the glass substrate W desired to be obtained by this etching. Further, a target etching amount (Vet1) is obtained from this etching film thickness and the number of glass substrates W to be etched at one time (etching area). Then, the obtained etching amount (Vet1) is set by inputting from the input unit 5b of the etching apparatus.

  Next, dilute hydrofluoric acid having a predetermined concentration is stored as an etchant L in the processing tank 1 of the etching apparatus. The dilute hydrofluoric acid concentration is preferably the same as the dilute hydrofluoric acid used in the above-described test etching, but may be a different concentration.

  Next, a predetermined number of glass substrates W to be processed are immersed in the etching chemical solution L in the processing tank 1. Thereby, etching of the glass substrate W is started. Simultaneously with the start of etching, measurement of the temperature of the etching chemical liquid L by the temperature measuring means 2 and measurement of the concentration of the reaction product in the etching chemical liquid L by the concentration measuring means 3 are started.

  Then, the temperature of the etching chemical L measured by the temperature measuring means 2 is monitored, and based on the etching amount (Vet1) set by the input unit 5 and the relationship of FIG. Etching is terminated with the point in time when the temperature rise (Td) of the etching chemical L reaches a predetermined value (Td1) corresponding to the etching amount (Vet1) as the end point of etching. And it is set as the state which pulled up the glass substrate W from the etching chemical | medical solution L in the processing tank 1. FIG.

  Note that the vertical axis in the graph of FIG. 3 is the temperature rise amount (Td), and the temperature at which etching is started may be any number, and corresponds to the temperature rise of the etching chemical L from the time when etching is started. ing. For this reason, when the temperature of the etching chemical L is lowered by adding the etching chemical L during the etching, the temperature from the time when the etching chemical L is added to the amount of increase in temperature from the time when the etching is started. A value obtained by accumulating the increase amount may be used as the temperature increase amount. This is the same even when the etching chemical L is changed during the etching.

  In addition to the etching end point detection as described above, the concentration of the reaction product in the etching chemical L measured by the concentration measuring means 3 is monitored, and the etching amount (Vet1) set by the input unit 5 is monitored. Further, based on the relationship of FIG. 5 stored in the storage means 4, etching is performed when the concentration change of the reaction product in the etching chemical L reaches a predetermined state (Cd1) corresponding to the etching amount (Vet1). It may be the end point.

  The vertical axis in the graph of FIG. 5 is the concentration change (Cd) of the reaction product. Depending on the concentration of the reaction product at the start of etching, the concentration change (Cd) of the subsequent reaction product and the etching amount The relationship is different. Therefore, for example, if the concentration of the reaction product at the start of etching is 0%, the etching is performed when the concentration of the reaction product (Cd1) is reached corresponding to the etching amount 0 to the etching amount (Vet1). Terminate. If the concentration of the reaction product at the start of etching is not 0%, the etching amount (Vet1 + Vet0) is obtained by adding the etching amount (Vet1) to the etching amount (Vet0) at the concentration Cd0 of the reaction product at the start of etching. = Etching is terminated when the concentration (Cd1 ') corresponding to Vet1') is reached. Therefore, when the concentration of the reaction product in the etching chemical L is reduced by adding the etching chemical L during the etching, the amount of etching from the time when the etching is started and the time from when the etching chemical L is added. Etching is terminated at a concentration (Cd) at which the value obtained by accumulating the etching amount becomes the set etching amount.

  Note that, as described above, the etching may be terminated when the time + α has elapsed since the end point of the etching was detected. In this case, this α is preferably within 1 minute.

  Further, the etching end point detection based on the temperature rise amount of the etching chemical L described above and the etching end point detection based on the concentration change of the reaction product in the etching chemical L may be performed in combination. For example, the configuration may be such that the etching is terminated when the temperature rise amount of the etching chemical L reaches a predetermined value and the concentration change of the reaction product in the etching chemical L reaches a predetermined state. Furthermore, on the assumption that the temperature rise amount of the etching chemical solution L has reached a predetermined value, the etching is terminated when the concentration change amount of the reaction product in the etching chemical solution L reaches the predetermined value in this state. Anyway.

  Then, the end point detection of etching as described above is performed by the control unit 5c.

  Etching as described above can be repeated by replacing the glass substrate W in the etching chemical solution L without exchanging the etching chemical solution L as long as the etching rate by the etching chemical solution L is maintained to some extent.

  Further, when the etching rate by the etching chemical L is not maintained due to the repetition of etching, the etching chemical L in the processing tank 1 is sent to the recycle tank 14. The etching chemical L sent to the recycle tank 14 is left for a predetermined time to precipitate the reaction product. Thereafter, this precipitation liquid is extracted from the recycle tank 14 and sent to a waste liquid system. On the other hand, the supernatant liquid from which the reaction product has been precipitated is sent as a recycle liquid to the preparation tank 6 via the liquid sending system 16 and supplied from the pure water tank 8 and from the hydrofluoric acid tank 9. Along with the acid, the temperature is controlled again by adjusting it to a predetermined concentration. At this time, the etching chemical solution L in the preparation tank 6 is sufficiently stirred and managed to a uniform concentration by the circulation system 10, and the concentration is managed by the hydrofluoric acid concentration meter 12 disposed in the circulation system 10.

  And the etching chemical | medical solution L containing a recycle liquid is supplied to the processing tank 1, and the etching mentioned above is repeatedly performed using this etchant L.

  According to the etching method described above, the etching amount is determined by the configuration in which the etching is terminated based on the temperature rise amount of the etching chemical having a correlation with the etching amount and the change in the concentration of the reaction product in the etching chemical. It becomes possible to detect the end point of etching by directly grasping itself. Therefore, by controlling the etching amount with high accuracy, even a very thin glass substrate can be thinned with high accuracy. In addition, the amount of etching can be controlled in-line without requiring special work such as actually measuring the film thickness by pulling up the glass substrate W, which is the substrate to be etched, from the etching chemical solution, which requires special labor. Nor.

  Therefore, even when etching an extremely thin glass substrate W, it is possible to perform etching with good controllability without lengthening the process time. As a result, for example, in the manufacturing process of the liquid crystal panel, it is possible to further reduce the thickness of the liquid crystal panel.

  Furthermore, as described above, since it is not necessary to keep the concentration of the etching chemical liquid constant for controlling the etching amount, it is possible to reuse the etching chemical liquid once used as a recycling liquid, thereby reducing the cost. It is also possible to plan.

  In particular, it is possible to control the etching amount with higher accuracy by combining the temperature increase amount of the etching chemical and the concentration change of the reaction product in the etching chemical to terminate the etching.

  And according to the etching apparatus demonstrated using FIG. 1, it becomes possible to perform the etching method of this invention mentioned above. In the case where the etching end point is detected based only on the temperature rise amount of the etching chemical L, it is not necessary to provide the concentration measuring means 3 in the etching apparatus. Further, when the etching end point is detected based only on the concentration change of the reaction product in the etching chemical L, it is not necessary to provide the temperature measuring means 2 in the etching apparatus.

  In the above embodiment, the etching is terminated based on the graph showing the relationship between the temperature change amount and concentration change of the etching chemical solution and the etching amount as shown in FIGS. However, for example, as shown in FIG. 6, a list showing the amount of temperature increase for achieving the target film thickness of the glass substrate for each number of glass substrates is prepared in advance, and this list is used. The etching may be terminated when the temperature rises. The list in FIG. 6 shows an example in which the initial glass substrate W having a thickness of 1.40 mm is thinned to each target thickness.

It is a block diagram of the etching apparatus of embodiment. It is sectional drawing and a top view which show the structure of the processing tank of an etching apparatus. It is a graph which shows the relationship between the temperature rise amount of an etching chemical | medical solution, and the etching amount. It is a graph which shows the relationship between the temperature rise amount of an etching chemical | medical solution, and an etching film thickness. It is a graph which shows the relationship between the density | concentration change of the reaction product in an etching chemical | medical solution, and etching amount. It is a table | surface with the target board thickness of an etching, and the temperature rise amount of an etching chemical | medical solution.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Processing tank, 2 ... Temperature measuring means, 3 ... Concentration measuring means, 4 ... Memory | storage means, 5 ... Control means, L ... Etching chemical | medical solution, W ... Glass substrate (substrate to be etched)

Claims (7)

An etching method for performing etching by immersing a substrate to be etched in an etching chemical solution,
Obtain in advance the relationship between the amount of temperature rise of the etching chemical during the etching and the etching amount of the substrate to be etched,
Etching is terminated when the temperature increase amount of the etching chemical solution reaches a predetermined value corresponding to the set etching amount based on the relationship. An etching method for performing etching by immersing a substrate to be etched in an etching chemical solution,
The relationship between the concentration change of the reaction product generated in the etching chemical during the etching and the etching amount of the substrate to be etched is obtained in advance.
Etching is terminated when a change in the concentration of the reaction product reaches a predetermined state corresponding to a set etching amount based on the relationship. The etching method according to claim 2, wherein
The substrate to be etched is a glass substrate;
The etching chemical is a diluted hydrofluoric acid solution,
The etching method, wherein the reaction product is hydrogen silicofluoride (H2SiF6, hexanefluorosilicic acid). The etching method according to claim 2, wherein
In addition to the relationship between the concentration change of the reaction product and the etching amount of the substrate to be etched, the relationship between the amount of temperature rise of the etching chemical during the etching and the etching amount of the substrate to be etched is obtained in advance.
Etching is terminated when the concentration change of the reaction product and the temperature increase amount of the etching chemical solution reach a predetermined state corresponding to the set etching amount based on the two relations. Method. A processing tank in which an etching chemical solution is stored and a substrate to be etched is accommodated in a state of being immersed in the etching chemical solution,
Temperature measuring means for measuring the temperature of the etching chemical stored in the processing tank;
Storage means for storing the relationship between the temperature rise amount of the etching chemical during etching and the etching amount of the substrate to be etched;
Based on the relationship stored in the storage means, the etching from the etching chemical solution in the processing tank when the temperature rise measured by the temperature measurement means reaches a predetermined value corresponding to the set etching amount. An etching apparatus comprising: control means for bringing the substrate up. A processing tank in which an etching chemical solution is stored and a substrate to be etched is accommodated in a state of being immersed in the etching chemical solution,
Concentration measuring means for measuring the concentration of the reaction product in the etching chemical stored in the treatment tank;
Storage means for storing a relationship between a concentration change of the reaction product generated in the etching chemical during etching and an etching amount of the substrate to be etched;
Based on the relationship stored in the storage means, the etching substrate from the etching chemical solution in the processing tank when the concentration change measured by the concentration measuring means reaches a predetermined state corresponding to the set etching amount. Etching apparatus, characterized by comprising control means for bringing the substrate into a raised state. The etching apparatus according to claim 6, wherein
Further comprising temperature measuring means for measuring the temperature of the etching chemical stored in the processing tank,
The storage means stores the relationship between the concentration change of the reaction product and the etching amount of the substrate to be etched, and the relationship between the temperature increase amount of the etching chemical during etching and the etching amount of the substrate to be etched. ,
In the control means, based on the respective relationships stored in the storage means, the density change measured by the density measurement means and the temperature rise measured by the temperature measurement means correspond to a predetermined etching amount. When the state is reached, the etching base is pulled up from the etching chemical solution in the processing tank.

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