JP2012251223A - Sulfuric acid solution supply system and sulfuric acid solution supply method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sulfuric acid solution supply system which achieves a continuous stable operation by preventing mixing of a solid matter into an electrolytic apparatus by a simple apparatus structure, and to provide a sulfuric acid solution supply method.SOLUTION: The sulfuric acid solution supply system includes: a cooler 25 for cooling a sulfuric acid solution; an electrolytic cell 4 for electrolyzing the sulfuric acid solution; an electrolysis-side circulation line for returning the sulfuric acid solution used in a batch-type cleaning machine 2 to the batch-type cleaning machine 2 through the cooler 25 and the electrolytic cell 4 in this order; and a use-side circulation line for returning the sulfuric acid solution used in the batch-type cleaning machine 2 to the batch-type cleaning machine 2 without through the cooler 25. The electrolysis-side circulation line and the use-side circulation line have a common liquid discharge line 10 through which the sulfuric acid solution discharged from the batch-type cleaning machine 2 flows, and the respective circulation lines are branched from the branching point 10a at the end part on the downstream side of the common liquid discharge line 10, and further, a cleaning machine-side filter 21 for capturing a solid matter is provided in the common liquid discharge line 10.

Description

  The present invention relates to a sulfuric acid solution supply system and a sulfuric acid solution supply method for supplying an electrolyzed sulfuric acid solution to a use side, and in particular, a sulfuric acid solution supply system and a sulfuric acid solution supply method for capturing solid matter in a circulating sulfuric acid solution with a filter. About.

  A cleaning system for cleaning a semiconductor substrate such as a silicon wafer and other substrates using a sulfuric acid solution containing persulfuric acid produced by electrolyzing a sulfuric acid solution as a cleaning liquid is known.

  In the above cleaning system, if a wafer with a resist attached is cleaned with a cleaning solution without passing through an ashing process in which the resist is oxidized and ashed, the resist may be peeled off from the wafer in the form of a film. In particular, in the case of a wafer in which a resist is formed thick or a wafer in which a dopant is implanted at a high dose, the resist tends to peel off in the form of a film.

In the case of a resist piece peeled in the form of a film, when an oxidizing agent such as persulfuric acid contained in the cleaning liquid comes into contact with the resist piece, it is considered that organic substances are gradually decomposed from the surface in contact with the oxidizing agent.
In particular, when dopant is implanted at a high dose, it is considered that the organic matter is gradually decomposed from the back side of the resist piece because the organic matter is hardly decomposed on the resist piece surface on the dopant injection side. For this reason, when dopant is implanted at a high dose, the contact efficiency between the oxidant and the resist piece is low, and the resist is peeled off from the wafer when high load operation is performed with a short cleaning time per wafer. Even if done, solid undecomposed resist such as a film-like resist piece is likely to be mixed into the circulation line.
If the solid undecomposed resist mixed in the circulation line is sent to the electrolysis apparatus together with the sulfuric acid solution and mixed in the electrolytic cell and adheres to the electrode, the current hardly flows and the voltage between the electrodes rises. If the interelectrode voltage rises excessively, the safety device operates as a voltage abnormality and the electrolysis device stops. In addition, solid sulfur is likely to be deposited due to an increase in the voltage between the electrodes, and the electrolytic cell may be blocked.

To solve the above problem, a cleaning system using an SS trapping filter that traps and removes suspended suspended solids (SS) from a solution has been proposed (see Patent Documents 1 and 2).
In the cleaning system, an SS trapping filter is provided between the cleaning tank and a cooler provided in front of the electrolytic cell. In this SS trapping filter, when a wafer implanted with a dopant at a high dose is cleaned without passing through an ashing process, a relatively large solid undecomposed resist mixed in the cleaning drainage is trapped. be able to. The cleaning waste liquid obtained by capturing and removing the solid undecomposed resist by the SS capturing filter is sent to the electrolysis apparatus. When the solid undecomposed resist is captured by the SS capturing filter, the organic matter in the captured undecomposed resist is gradually decomposed by persulfuric acid and high-concentration sulfuric acid contained in the cleaning waste liquid that is subsequently passed.

A conventional cleaning system including the above-described circulation line and provided with a filter for capturing SS will be described with reference to FIG. FIG. 5 is a schematic view showing a one-loop cleaning system provided with a filter as described above.
The cleaning system includes a batch type cleaning machine 102 that cleans a plurality of semiconductor wafers 100 together, an electrolysis cell 104 that electrolyzes a sulfuric acid solution, and one circulation line 110 through which the sulfuric acid solution circulates.

The batch type cleaning machine 102 has a cleaning tank 102a filled with an electrolyzed sulfuric acid solution and a heater 102b installed in the cleaning tank 102a.
The feed side of the circulation line 110 is connected to the drain side of the cleaning tank 102a, and the return side of the circulation line 110 is connected to the liquid inlet side of the cleaning tank 102a.
On the feed side of the circulation line 110, a filter 124, a pump 120, and a cooler 131 are interposed in this order.

In addition, the liquid inlet side of the electrolytic cell 104 is connected to the downstream side of the cooler 131 on the feed side of the circulation line 110. On the return side of the circulation line 110 connected to the liquid discharge side of the electrolysis cell 104, a gas-liquid separator 132 for separating gas generated by electrolysis is interposed. An exhaust gas treatment device 133 for treating the gas separated by the gas-liquid separator 132 is connected to the gas discharge side of the gas-liquid separator 132.
A pump 126 is interposed on the return side of the circulation line 110 connected to the liquid discharge side of the gas-liquid separator 132, and the return side end of the circulation line 110 is connected to the cleaning tank 102a.

Next, the operation of the conventional cleaning system shown in FIG. 5 will be described.
The sulfuric acid solution accommodated in the washing tank 102a is sent to the electrolysis cell 104 through the feed side of the circulation line 110 by the pump 120, electrolyzed in the electrolysis cell 104 to generate persulfuric acid, and then passed through the return side of the circulation line 110. It returns to the washing tank 102a. This is repeated to electrolyze the sulfuric acid solution. At this time, the sulfuric acid solution is cooled by the cooler 131, and after electrolysis, the sulfuric acid solution is sent through the gas-liquid separator 132 by the pump 126 and circulated to the cleaning tank 102a.

  The sulfuric acid solution containing persulfuric acid sent into the cleaning tank 102a is heated by the heater 102b, and the resist and contaminants attached to the semiconductor wafer 100 immersed in the sulfuric acid solution are peeled and removed. The resist and the like that have been removed are transferred into a sulfuric acid solution.

  The sulfuric acid solution in the cleaning tank 102a is sequentially discharged through the circulation line 110 by the pump 120 as described above. At this time, the resist or the like transferred into the sulfuric acid solution is captured by the filter 124. After passing through the filter 124, the sulfuric acid solution is cooled by the cooler 131 as described above and sent to the electrolytic cell 104 to regenerate persulfuric acid. The semiconductor wafer 100 can be continuously cleaned by repeating the above steps.

Next, a conventional two-loop cleaning system provided with a filter for capturing SS will be described with reference to FIG.
The cleaning system includes a batch type cleaning machine 102 that cleans a plurality of semiconductor wafers 100 and an electrolysis cell 104 that electrolyzes a sulfuric acid solution, and two circulation lines (use-side circulation line, circulation side) through which the sulfuric acid solution circulates. Electrolysis side circulation line). The batch type cleaning machine 102 has a cleaning tank 102a and a heater 102b, similarly to the cleaning system shown in FIG.

  A common drain line 111 is connected to the liquid discharge side of the cleaning tank 102a, and a common supply line 114 is connected to the liquid inlet side of the cleaning tank 102a. The common drainage line 111 branches into two lines at the downstream end, and the two lines join the common supply line 114 at the upstream end. The junction 111a of the common drainage line 111 and the junction of the common supply line 114 A use-side circulation connection line 112 is connected to 114a. The common drain line 111, the use side circulation connection line 112, and the common supply line 114 constitute a use side circulation line. The washing machine 102 can circulate the sulfuric acid solution through the use side circulation line.

  A pump 120 is interposed in the common drain line 111. Further, a cooler 121 and a filter 122 are interposed in this order from the upstream side to the downstream side in the use side circulation connection line 112.

  Further, an electrolytic circulation connection line 113 is connected via the electrolytic cell 104 between the branch point 111 a of the common drainage line 111 and the junction 114 a of the common supply line 114. The common drainage line 111, the electrolytic circulation connection line 113, and the common supply line 114 constitute an electrolytic circulation line. The common drain line 111 and the common supply line 114 are shared by the use side circulation line and the electrolytic circulation line.

  A cooler 125 is provided on the feed side of the electrolytic circulation connection line 113, and a gas-liquid separator 132, a storage tank 103, a pump 126, and a sulfuric acid electrolyte side filter 127 are upstream on the return side of the electrolytic circulation connection line 113. It is installed in this order from the side to the downstream side. An exhaust gas treatment device 133 is connected to the gas separation side of the gas-liquid separator 132.

Next, the operation of the conventional cleaning system shown in FIG. 6 will be described.
The washing tank 102a is filled with a sulfuric acid solution, and the sulfuric acid solution is circulated through the use side circulation line and the electrolysis side circulation line. At this time, the electrolytic cell 104 is energized between the anode and the cathode, and the sulfuric acid solution passed through the electrolytic cell 104 is electrolyzed to obtain a sulfuric acid electrolytic solution. The washing tank 102a is filled with a sulfuric acid electrolyte solution having a predetermined persulfuric acid concentration by circulation of the sulfuric acid solution, and the sulfuric acid electrolyte solution is heated by the heater 102b.

A plurality of semiconductor wafers 100 are immersed and cleaned in the cleaning tank 102a.
The sulfuric acid solution in the cleaning tank 102a is drained through the common drain line 111 by the pump 120 along with the circulation. At the branch point 111 a of the common drainage line 111, a part of the sulfuric acid solution flows into the feed side of the electrolytic circulation connection line 113 and the remaining part flows into the use side circulation connection line 112.

The sulfuric acid solution that has flowed into the use-side circulation connection line 112 at the branch point 111a is forcibly cooled by the cooler 121, and then a solid content such as a resist is captured by the filter 122, and the sulfuric acid solution from which the solid content has been removed is obtained. It reaches the confluence 114a.
The sulfuric acid solution that has flowed into the forward path of the electrolytic circulation connecting line 113 at the branch point 111 a is forcibly cooled by the cooler 125 and then introduced into the liquid inlet side of the electrolytic cell 104.

  In the electrolysis cell 104, electrolysis is performed while a sulfuric acid solution is passed between the anode and the cathode energized by the power supply device, and persulfuric acid is generated in the sulfuric acid solution. The sulfuric acid solution containing persulfuric acid is drained from the outlet side of the electrolysis cell 104, and the gas generated by electrolysis is separated by the gas-liquid separator 132. The separated exhaust gas is sent to the exhaust gas treatment device 133 for exhaust gas treatment.

The sulfuric acid electrolyte from which the gas has been separated is stored in the storage tank 103. The sulfuric acid electrolytic solution stored in the storage tank 103 is sent by the pump 126 toward the junction 114a through the electrolytic circulation connection line 113. At this time, the filter 127 captures fine particles in the sulfuric acid electrolyte and solid matters such as sulfur precipitates generated by electrolysis and removes them from the sulfuric acid electrolytic solution.
The sulfuric acid electrolytic solution fed to the junction 114a through the return side of the electrolytic circulation connection line 113 joins the sulfuric acid solution fed through the use side circulation connection line 112 at the junction 114a, and then the common supply line 114. Is introduced to the liquid inlet side of the cleaning tank 102a and used again for cleaning.

  On the other hand, a three-loop type having three circulation lines through which a sulfuric acid solution circulates is known (see, for example, Patent Document 3). The system includes an electrolytic side reservoir circulation line that returns the sulfuric acid solution discharged from the storage tank to the storage tank via the electrolysis apparatus without passing through the heater, and the sulfuric acid solution introduced from the washing machine to the heater. The storage part circulation line on the washing machine side that returns the cooler and the storage tank to the washing machine in this order without passing through the heater, and the sulfuric acid solution introduced from the washing machine are passed through the heater without going through the cooler and the storage tank. There are three circulation lines on the washing machine side that return to the washing machine.

JP 2006-272170 A JP 2007-266477 A JP 2009-253057 A

  However, in a conventional cleaning system in which a plurality of circulation lines exist, it is necessary to provide a filter in each circulation line through which a sulfuric acid solution containing SS can flow, and the number of filters increases and the apparatus configuration is complicated. In addition, there is a problem that the management of the filter becomes a burden.

  The present invention has been made against the background of the above circumstances, and a sulfuric acid solution capable of realizing continuous and stable operation of the electrolysis apparatus by preventing solid matter from being mixed into the electrolysis apparatus with a simple apparatus configuration. An object is to provide a supply system and a sulfuric acid solution supply method.

  That is, among the sulfuric acid solution supply systems of the present invention, the first present invention is a sulfuric acid solution supply system for supplying an electrolyzed sulfuric acid solution to a use side, and a cooling means for cooling the sulfuric acid solution and electrolyzing the sulfuric acid solution. An electrolysis device, an electrolysis side circulation line for returning the sulfuric acid solution used on the use side to the use side through the cooling means and the electrolysis device in this order, and the sulfuric acid solution used on the use side. A use-side circulation line that returns to the use side without passing through the cooling means, and the electrolysis-side circulation line and the use-side circulation line share the sulfuric acid solution drained from the use side. Each having a common drain line and branching from a branch point at the downstream end of the common drain line, and the common drain line captures the solid matter in the sulfuric acid solution. Characterized in that it comprises a filter.

  The sulfuric acid solution supply system according to the second aspect of the present invention is a sulfuric acid solution supply system for supplying an electrolyzed sulfuric acid solution to a use side, a cooling means for cooling the sulfuric acid solution, a storage unit for storing the sulfuric acid solution, and the sulfuric acid solution. Used on the use side, an electrolyzer that electrolyzes, a use-side reservoir circulation line that returns the sulfuric acid solution used on the use side to the use side through the cooling means and the storage tank in this order. The use side circulation line for returning the sulfuric acid solution to the use side without passing through the cooling means and the storage tank, and the sulfuric acid solution discharged from the storage tank through the electrolyzer. A common common drainage line through which the sulfuric acid solution drained from the use side flows through the use side reservoir circulation line and the use side circulation line. Each of which is branched from a branch point at the downstream end of the common drainage line, and the common drainage line is provided with a filter for capturing solid matter in the sulfuric acid solution. Features.

  The sulfuric acid solution supply system according to a third aspect of the present invention further comprises a flow path resistance adjusting means or a flow rate adjusting means in the use side circulation line downstream of the branch point in the first or second aspect of the invention. It is characterized by.

  The sulfuric acid solution supply system according to a fourth aspect of the present invention is that, in the third aspect of the present invention, the flow path resistance adjusting means or the flow rate adjusting means is a valve, check or orifice interposed in the use side circulation line. Features.

  The sulfuric acid solution supply system according to a fifth aspect of the present invention is the above-described flow path resistance adjusting means provided in the use side circulation line branched from the branch point of the common drainage line in the third or fourth aspect of the present invention. The flow rate adjusting means is used as the first flow path resistance adjusting means or the flow rate adjusting means, and the second flow path resistance adjusting means or the flow rate adjusting means is provided in another circulation line branched from the branch point. To do.

  In the sulfuric acid solution supply system of the sixth aspect of the present invention, in any one of the first to fifth aspects of the present invention, the use side circulation line and the other circulation line for returning the sulfuric acid solution to the use side are the use. A common supply line for supplying a sulfuric acid solution to the side, and each joining a junction at an upstream end of the common supply line, and the use between the junction and the branch point The length of the side circulation line is 1 m or less, and the use side circulation line is provided with a check valve for preventing liquid flow from the junction to the branch point.

  The sulfuric acid solution supply system according to a seventh aspect of the present invention is characterized in that, in any one of the first to sixth aspects of the present invention, the filter has a pore diameter of 0.01 to 10 μm.

  The sulfuric acid solution supply system according to an eighth aspect of the present invention branches from the branch point using the filter provided in the common drain line as the first filter in any one of the first to seventh aspects of the present invention. A second filter having a hole diameter equal to or smaller than that of the first filter and having a hole diameter of 0.01 to 10 μm is provided on the downstream side of the electrolysis by the electrolyzer in the other circulation line. It is characterized by being.

  A sulfuric acid solution supply system according to a ninth aspect of the present invention is the pretreatment according to any one of the first to eighth aspects of the present invention, wherein the use side has a resist adhered by pattern processing, and the resist is oxidized and ashed in advance. It is a cleaning unit that cleans an electronic material substrate that has not undergone a process.

  A sulfuric acid solution supply method according to a tenth aspect of the present invention is a sulfuric acid solution supply method for supplying an electrolyzed sulfuric acid solution to a use side, wherein the sulfuric acid solution used on the use side is branched and electrolyzed after forcibly cooling a part thereof. The step A of circulating the sulfuric acid solution after electrolysis back to the use side and the step of circulating the remaining part of the branched sulfuric acid solution used on the use side back to the use side without forced cooling B, and before the branching of the sulfuric acid solution from the use side in the step A and the step B, the solid matter in the sulfuric acid solution is captured by passing through a filter. To do.

  An sulfuric acid solution supply method according to an eleventh aspect of the present invention is a sulfuric acid solution supply method for supplying an electrolyzed sulfuric acid solution to a use side, wherein the sulfuric acid solution used on the use side is branched and partly forcibly cooled and stored. Without the forced cooling, the process C which drains the sulfuric acid solution from the storage part and returns to the use side and circulates the remaining part branched from the sulfuric acid solution used on the use side. A step D for returning to the use side and circulating; and a step E for draining and electrolyzing the sulfuric acid solution from the storage part for storing the sulfuric acid solution, and returning and circulating the sulfuric acid solution after the electrolysis to the storage part. The solid solution in the sulfuric acid solution is captured by passing the solution through the filter before the branching of the sulfuric acid solution from the use side in the step C and the step D.

  According to the present invention, the electrolytic side circulation line for circulating the sulfuric acid solution drained from the use side and the use side circulation line have a common drain line, and the filter provided in the common drain line In both circulation lines, solids in the sulfuric acid solution are captured. As a result, it is possible to efficiently prevent the solid matter transferred into the sulfuric acid solution from flowing into the electrolysis apparatus through the electrolytic side circulation line as it is.

  According to another aspect of the present invention, the use side circulation line for circulating the sulfuric acid solution drained from the use side and the use side reservoir circulation line have a common drainage line in common. Solids in the sulfuric acid solution are captured in both circulation lines by a filter provided in the drainage line. As a result, it is possible to efficiently prevent the solid matter transferred into the sulfuric acid solution from flowing into the electrolysis apparatus through the electrolytic side circulation line as it is.

  In the present invention, the use side to which the electrolyzed sulfuric acid solution is supplied includes, for example, a cleaning unit that cleans an electronic material substrate to which a resist is adhered by pattern processing. Examples of the electronic material substrate include a silicon wafer, other semiconductor wafers, and a glass substrate. As an electronic material board | substrate, the thing which has not passed through the pre-processing process which oxidizes and ashes a resist previously may be sufficient. In addition, the cleaning unit may be a batch type cleaning machine that cleans a plurality of electronic material substrates together, or may be a single wafer cleaning unit that cleans the electronic material substrates one by one.

As a filter provided in the common drainage line, any filter may be used as long as it has a pore size capable of capturing solid matter such as undecomposed resist contained in the sulfuric acid solution drained from the use side. Specifically, the pore diameter of the filter provided in the common drain line is preferably 0.01 to 10 μm, and more preferably 1 μm or less.
The undecomposed resist captured by the filter is decomposed by persulfuric acid or high-concentration sulfuric acid contained in the sulfuric acid solution and dissolved in the solution. For this reason, the filter is not clogged with the undecomposed resist.

  In addition, the filter provided in the said common drainage line can be used as a 1st filter, and a 2nd filter can also be provided in the electrolysis side circulation line or use side storage part circulation line branched from the branch point in a common drainage line. it can. As the second filter, a filter having a hole diameter equivalent to that of the first filter or a hole diameter smaller than that of the first filter and having a hole diameter of 0.01 to 10 μm can be suitably used. The first filter can remove the solid matter having a problem size by flowing into the electrolysis apparatus, and can remove the solid matter particles that do not cause a problem in the electrolysis apparatus downstream of the electrolysis apparatus. . When sulfur deposits flow out in the electrolytic reaction device, they can be captured by the second filter.

  The flow rate of the sulfuric acid solution flowing through each circulation line is appropriately set according to the required amount of the sulfuric acid solution on the use side. However, even in the conventional system, the flow rate of the electrolysis side circulation line and the use side reservoir circulation line is usually set smaller than the flow rate of the use side circulation line on the downstream side of the branch point of the common drainage line. In such a setting, the channel cross-sectional area of the electrolysis-side circulation line and the use-side reservoir circulation line is made smaller than the channel cross-sectional area of the use-side circulation line. If a filter is provided in the use-side circulation line after branching the common drain line as in the past, the filter becomes a flow path resistance, and the sulfuric acid solution smoothly flows into the electrolysis-side circulation line and the use-side reservoir circulation line. Flows. However, in the present invention in which a filter is provided in the common drainage line, since it is assumed that no filter is provided in the use side circulation line, the flow resistance of the use side circulation line is reduced, and the electrolytic side circulation line and the use side storage are reduced. A phenomenon occurs in which a necessary amount of sulfuric acid solution does not flow into the partial circulation line.

  Therefore, a flow path resistance adjusting means or a flow rate adjusting means is provided in the use side circulation line downstream of the branch point so as to adjust the flow resistance of the use side circulation line to a high level or to adjust the flow rate. A required amount of sulfuric acid solution is allowed to flow into the electrolytic side circulation line and the use-side reservoir circulation line on the downstream side. As the flow path resistance adjusting means or the flow rate adjusting means, a needle valve, a stop valve, a pressure adjusting valve, a constant flow valve or other valve, a check, an orifice, or the like can be used.

The use side circulation line and the electrolysis side circulation line or the use side reservoir circulation line have a common common supply line for supplying sulfuric acid solution to the use side, and at the upstream end of the common supply line. It can be set as the structure each joined to a certain junction. In this case, when the length of the use-side circulation line between the junction and the branch point becomes 1 m or less, the flow path resistance of this line becomes extremely low, and the sulfuric acid solution flows from the junction to the branch point. There is a risk of backflow.
Therefore, in order to prevent the sulfuric acid solution from flowing back from the junction point to the branch point, it is preferable to provide a check valve in the use side circulation line between the junction point and the branch point. By providing a check valve, the reverse flow of the sulfuric acid solution is prevented according to fluctuations in the hydraulic pressure of the sulfuric acid solution due to the pulsation of the pump for sending the sulfuric acid solution in each circulation line, and the sulfuric acid solution A positive stream can flow. That is, if the hydraulic pressure in the use-side circulation line upstream of the confluence is lower than the hydraulic pressure in the electrolysis-side circulation line or use-side reservoir circulation line upstream of the confluence, the check valve The opening / closing part is closed, and the reverse flow of the sulfuric acid solution can be prevented. If the hydraulic pressure in the use-side circulation line upstream of the junction is higher than the hydraulic pressure in the electrolysis-side circulation line or use-side reservoir circulation line upstream of the junction, the check valve The opening / closing part is opened, and a positive flow of the sulfuric acid solution can flow.

Further, the flow path resistance adjusting means or the flow rate adjusting means provided in the use side circulation line downstream of the branch point is used as the first flow path resistance adjusting means or the flow rate adjusting means. A second flow path resistance adjusting means or a flow rate adjusting means may be provided in the line. Thereby, the flow volume in an electrolysis side circulation line or a use side storage part circulation line can be adjusted to a fixed range. As the second channel resistance adjusting unit or the flow rate adjusting unit, a valve, a check, an orifice, or the like can be used similarly to the first channel resistance adjusting unit or the flow rate adjusting unit.
Some flow resistance adjusting means also function as flow rate adjusting means, and conversely, some flow rate adjusting means also function as flow path resistance adjusting means. That is, the valve, check, orifice, and the like listed as specific examples of the first and second flow path resistance adjusting means or the flow rate adjusting means correspond to one or both of the flow path resistance adjusting means and the flow rate adjusting means.

  Specific examples of the first and second filters include PTFE (polytetrafluoroethylene), PFA (tetrafluoroethylene / perfluoroalkyl vinyl ether copolymer), and FEP (tetrafluoroethylene / hexafluoropropylene). Copolymer) and other MF (microfilter) made of Teflon (registered trademark). In the case of MF, it is preferable to replace the MF at a frequency of about once every several years. However, when replacing the MF, the sulfuric acid solution in each circulation line provided with each filter is discharged and replaced with water. It is preferable to replace the filter.

  Moreover, it is preferable that the member which comprises the said 1st and 2nd flow-path resistance adjustment means or flow volume adjustment means has acid resistance, oxidation resistance, and temperature resistance. Specific examples of such members include PTFE, PFA, FEP and other Teflon (registered trademark).

  According to the present invention, it is possible to realize the continuous and stable operation of the electrolyzer by preventing the solid matter from being mixed into the electrolyzer with a simple device configuration, and effectively removing the solid matter. The solution can be circulated to the use side.

It is the schematic which shows the sulfuric acid solution supply system of one Embodiment of this invention. Similarly, it is the schematic which shows the sulfuric acid solution supply system of other embodiment. Similarly, it is the schematic which shows the example of a change of the sulfuric acid solution supply system of embodiment shown in FIG. It is a graph which shows the relationship between the elapsed time from the system operation start obtained about each of the washing | cleaning system of an Example and a comparative example, and the voltage between electrodes in an electrolysis cell. It is the schematic which shows the conventional 1 loop type washing | cleaning system. It is the schematic which shows the conventional 2 loop type washing | cleaning system.

(Embodiment 1)
Below, the sulfuric acid solution supply system 1 of one Embodiment of this invention is demonstrated based on FIG.
The sulfuric acid solution supply system 1 includes a batch type cleaning machine 2 that collectively cleans a plurality of semiconductor wafers 100 and an electrolytic cell 4 that electrolyzes the sulfuric acid solution, and two circulation lines (use side circulation) through which the sulfuric acid solution circulates. Line, electrolytic side circulation line). The batch type cleaning machine 2 corresponds to the use side of the present invention. The electrolysis cell 4 constitutes a part of the electrolysis apparatus of the present invention. The electrolysis cell 4 includes an electrode having at least an anode as a diamond electrode, and a power supply device (not shown) that energizes between the anode and the cathode. The electrode may include a bipolar electrode.

  The batch type cleaning machine 2 includes a cleaning tank 2a filled with an electrolyzed sulfuric acid solution, and a heater 2b installed at the bottom of the cleaning tank 2a. Further, the batch type cleaning machine 2 includes a high temperature rinsing tank for rinsing the semiconductor wafer 100 after cleaning in the cleaning tank 2a, a room temperature rinsing tank for further rinsing the semiconductor wafer 100 after rinsing in the high temperature rinsing tank, and a room temperature rinsing tank And a drier for drying the semiconductor wafer 100 after rinsing (none is shown). Each of the cleaning tank 2a, the high temperature rinsing tank, and the room temperature rinsing tank includes, for example, one tank or two tanks.

The cleaning tank 2a is composed of a member having heat resistance of, for example, 100 ° C. or higher, and is made of, for example, quartz.
The heater 2b heats the sulfuric acid solution in the cleaning tank 2a to, for example, 120 ° C. or higher and 190 ° C. or lower (preferably 150 ° C. or lower). For example, a quartz heater is used.
As the high-temperature rinsing tank, for example, one made of Teflon (registered trademark) or quartz is used. The temperature of the rinse liquid in the high-temperature rinse tank is preferably 60 ° C. or higher.
The material of the room temperature rinse tank is not particularly limited.
The semiconductor wafer 100 is attached with a resist by pattern processing, for example, and may not have undergone a pretreatment process (ashing process) in which the resist is oxidized and ashed in advance, and has undergone an ashing process. It may be. However, there is a tendency that a resist piece is more likely to occur without passing through the ashing process, and the problem becomes remarkable.

  A common drain line 10 is connected to the liquid discharge side of the cleaning tank 2a, and a common supply line 13 is connected to the liquid input side of the cleaning tank 2a. The common drainage line 10 branches into two lines at the downstream end, and the common supply line 13 joins the two lines at the upstream end. The junction 10a of the common drainage line 10 and the junction of the common supply line 13 The use side circulation connection line 11 is connected to 13a. The common drain line 10, the use side circulation connection line 11, and the common supply line 13 constitute a use side circulation line. The washing machine 2 can circulate the sulfuric acid solution through the use side circulation line. Each line is made of a material having heat resistance to a temperature of 100 ° C. or higher, and can be made of, for example, PFA or other Teflon (registered trademark).

The common drain line 10 is provided with a pump 20 and a washing machine side filter 21 in this order from the upstream side to the downstream side. Further, a flow rate adjustment valve 22 is interposed in the use side circulation connection line 11.
A heat resistant diaphragm pump or the like can be used as the pump 20, and it is desirable to use PTFE, PFA, FEP or the like as a material in contact with the solution.
The washer-side filter 21 corresponds to the first filter of the present invention. The flow rate adjusting valve 22 corresponds to the first flow path resistance adjusting means or the flow rate adjusting means of the present invention.
As the washer-side filter 21, for example, PTFE, PFA, FEP and other TF made of Teflon (registered trademark) can be used, and the pore size of the washer-side filter 21 is in the range of 0.01 to 10 μm. The pore diameter is preferably 1 μm or less.
The flow rate adjusting valve 22 is made of, for example, PTFE, PFA, FEP or other Teflon (registered trademark).
In the present invention, a check, an orifice, or the like may be used instead of the flow rate adjustment valve 22.

In addition, an electrolytic circulation connection line 12 is connected between the branch point 10a of the common drain line 10 and the junction 13a of the common supply line 13 via the electrolytic cell 4 so that the sulfuric acid solution can be circulated. It has become. The common drainage line 10, the electrolytic circulation connection line 12, and the common supply line 13 constitute the electrolytic circulation line of the present invention. The electrolytic circulation connection line 12 is made of a material having heat resistance with respect to a temperature of 100 ° C. or higher, and can be made of, for example, PFA or other Teflon (registered trademark).
As described above, the common drain line 10 and the common supply line 13 are shared by the use-side circulation line and the electrolytic circulation line.

A flow rate adjusting valve 24 and a cooler 25 are provided in this order from the upstream side to the downstream side on the forward path side of the electrolytic circulation connection line 12. The flow rate adjusting valve 24 corresponds to a second flow path resistance adjusting unit or a flow rate adjusting unit of the present invention. The cooler 25 corresponds to the cooling means of the present invention.
A gas-liquid separator 26, a pump 27, and a sulfuric acid electrolyte side filter 28 are provided in this order from the upstream side to the downstream side on the return path side of the electrolytic circulation connection line 12. An exhaust gas line 30 is connected to the gas separation side of the gas-liquid separator 26, and an exhaust gas treatment device 31 is connected to the other end side of the exhaust gas line 30. The sulfuric acid electrolyte side filter 28 corresponds to the second filter of the present invention.

The flow rate adjusting valve 24 is made of, for example, PTFE, PFA, FEP or other Teflon (registered trademark).
A heat resistant diaphragm pump or the like can be used as the pump 27, and it is desirable to use PTFE, PFA, FEP or the like as a material in contact with the solution.
As the sulfuric acid electrolyte side filter 28, for example, PTFE, PFA, FEP and other MF made of Teflon (registered trademark) can be used, and the pore diameter of the sulfuric acid electrolyte side filter 28 is within a range of 0.01 to 10 μm. The pore diameter is preferably 1 μm or less.

Next, the operation of the sulfuric acid solution supply system 1 shown in FIG. 1 will be described.
In this system, a sulfuric acid solution having a sulfuric acid concentration of 70 to 96% by mass is preferably used.
The washing tank 2a is filled with the sulfuric acid solution, and the sulfuric acid solution circulates through the use-side circulation line and the electrolysis-side circulation line at a circulation flow rate of 1/2 to 1/3 V / min with respect to the tank volume V of the washing tank 2a. Is done. At this time, the electrolytic cell 4 is energized between the anode and the cathode, and the sulfuric acid solution passed through the electrolytic cell 4 is electrolyzed to obtain a sulfuric acid electrolytic solution. The washing tank 2a is filled with a sulfuric acid electrolyte having a predetermined persulfuric acid concentration by circulation of the sulfuric acid solution, and the sulfuric acid electrolyte is heated to 120 ° C. or higher and 190 ° C. or lower (preferably 150 ° C. or lower) by the heater 2b. Is done.

A plurality of semiconductor wafers 100 are immersed and cleaned in the cleaning tank 2a.
The sulfuric acid solution in the cleaning tank 2a is drained through the common drain line 10 by the pump 20 along with the circulation. The sulfuric acid solution drained to the common drain line 10 captures solid content such as resist by the washing machine side filter 21, and the sulfuric acid solution from which this solid content has been removed reaches the branch point 10a. In the washer-side filter 21, the solid content captured by an oxidizing substance such as persulfuric acid remaining in the sulfuric acid solution to be continuously fed is gradually dissolved, and finally the washer-side filter 21 is washed without clogging. The liquid passes through the hole of the machine-side filter 21 and is sent downstream.

At the branch point 10a, a part of the sulfuric acid solution flows into the forward path of the electrolytic circulation connection line 12, and the remaining part flows into the use-side circulation connection line 11. At this time, the flow rate of the use-side circulation connection line 11 is adjusted by the flow rate adjustment valve 22, the flow rate of the electrolytic circulation connection line 12 is adjusted by the flow rate adjustment valve 24, and the flow rate of each line is adjusted to a predetermined range. Thereby, it is possible to avoid the occurrence of problems such as a shortage of the flow rate of one line after branching. In this embodiment, the flow rate adjusting valve is provided in each line, but it may be provided only in the use side circulation connection line 11.
Moreover, it may replace with what adjusts a flow volume and what uses what adjusts flow resistance, such as an orifice, may be used.

  The sulfuric acid solution that has flowed in an appropriate amount into the forward path of the electrolytic circulation connection line 12 at the branch point 10 a passes through the flow rate adjusting valve 24, is forcibly cooled by the cooler 25, and is introduced to the liquid inlet side of the electrolytic cell 4. In the cooler 25, the sulfuric acid solution is forcibly cooled to a temperature suitable for electrolysis in the electrolytic cell 4 (for example, 30 ° C. to 70 ° C.).

  In the electrolytic cell 4, electrolysis is performed while a sulfuric acid solution is passed between the anode and the cathode that are energized by the power supply device, and persulfuric acid is generated in the sulfuric acid solution. The sulfuric acid solution containing persulfuric acid is drained from the outlet side of the electrolytic cell 4, and the gas generated by electrolysis is separated by the gas-liquid separator 26. The separated exhaust gas is sent to the exhaust gas treatment device 31 through the exhaust gas line 30 to be subjected to exhaust gas treatment.

The sulfuric acid electrolyte from which the gas has been separated is fed through the electrolytic circulation connection line 12 by the pump 27. At this time, solid matters such as fine particles in the sulfuric acid electrolyte and sulfur precipitates generated by electrolysis are captured and removed from the sulfuric acid solution by the sulfuric acid electrolyte side filter 28, and then joined through the return path of the electrolytic circulation connection line 12. The sulfuric acid electrolyte solution fed to the point 13a merges with the sulfuric acid solution fed through the use-side circulation connection line 11 at the junction 13a, and then introduced into the liquid inlet side of the cleaning tank 2a through the common supply line 13. Used again for cleaning.

  The semiconductor wafer that has been cleaned in the cleaning machine 2 is rinsed in a high-temperature rinse bath and a normal-temperature rinse bath, and then dried in a drier to finish the process.

(Embodiment 2)
Next, a sulfuric acid solution supply system 1a according to another embodiment of the present invention will be described with reference to FIG. In addition, about the component similar to the said Embodiment 1, the same code | symbol is attached | subjected and description is abbreviate | omitted or simplified.

  In the sulfuric acid solution supply system 1a of the present embodiment, the batch type washing machine 2 and the electrolytic cell 4 for electrolyzing the sulfuric acid solution are provided as in the above embodiment, and the storage tank 3 for storing the sulfuric acid solution, and the sulfuric acid solution. Are provided with three circulation lines (use side circulation line, use side reservoir circulation line, and electrolysis side reservoir circulation line).

  A common drain line 10 is connected to the liquid discharge side of the cleaning tank 2a, and a common supply line 13 is connected to the liquid input side of the cleaning tank 2a. The common drainage line 10 branches into two lines at the downstream end, and the common supply line 13 joins the two lines at the upstream end. The junction 10a of the common drainage line 10 and the junction of the common supply line 13 The use side circulation connection line 11 is connected to 13a. The common drain line 10, the use side circulation connection line 11, and the common supply line 13 constitute a use side circulation line. The washing machine 2 can circulate the sulfuric acid solution through the use side circulation line. Each line is made of a material having heat resistance to a temperature of 100 ° C. or higher, and can be made of, for example, PFA or other Teflon (registered trademark).

The common drain line 10 is provided with a pump 20 and a washing machine side filter 21 in this order from the upstream side to the downstream side. Further, a flow rate adjustment valve 22 is interposed in the use side circulation connection line 11.
The washer-side filter 21 corresponds to the first filter of the present invention. The flow rate adjusting valve 22 corresponds to the first flow path resistance adjusting means or the flow rate adjusting means of the present invention.
As the washer-side filter 21, for example, PTFE, PFA, FEP and other TF made of Teflon (registered trademark) can be used, and the pore size of the washer-side filter 21 is in the range of 0.01 to 10 μm. The pore diameter is preferably 1 μm or less.

In addition, a use-side reservoir circulation connection line 14 is connected to the branch point 10a of the common drain line 10 and the junction 13a of the common supply line 13 via the reservoir 3, so that the washing machine 2 and the reservoir 3 are connected. The sulfuric acid solution can be circulated between the two. The common drain line 10, the use side reservoir circulation connection line 14, and the common supply line 13 constitute the use side reservoir circulation line of the present invention. The storage tank 3 and the use side storage part circulation connection line 14 are made of a material having heat resistance with respect to a temperature of 100 ° C. or higher, and can be made of, for example, PFA or other Teflon (registered trademark).
As described above, the common drainage line 10 and the common supply line 13 are shared by the use side circulation line and the use side reservoir circulation line.

A flow rate adjusting valve 24 and a cooler 25 are provided in this order from the upstream side to the downstream side on the forward path side of the use side reservoir circulation connection line 14 and are connected to the storage tank 3 at the downstream end. The flow rate adjusting valve 24 corresponds to a second flow path resistance adjusting unit or a flow rate adjusting unit of the present invention. The cooler 25 corresponds to the cooling means of the present invention.
In addition, a pump 27 and a sulfuric acid electrolyte side filter 28 are provided in this order from the upstream side to the downstream side on the return path side of the use side reservoir circulation connection line 14, and the downstream end is at the junction 13a. It is connected. The sulfuric acid electrolyte side filter 28 corresponds to the second filter of the present invention.

The flow rate adjusting valve 24 is made of, for example, PTFE, PFA, FEP or other Teflon (registered trademark).
A heat resistant diaphragm pump or the like can be used as the pump 27, and it is desirable to use PTFE, PFA, FEP or the like as a material in contact with the solution.
As the sulfuric acid electrolyte side filter 28, for example, PTFE, PFA, FEP and other MF made of Teflon (registered trademark) can be used, and the pore diameter of the sulfuric acid electrolyte side filter 28 is within a range of 0.01 to 10 μm. The pore diameter is preferably 1 μm or less.

  In addition, an electrolytic side storage part circulation line 15 is connected to the other liquid discharge side and the other liquid input side of the storage tank 3 via the electrolytic cell 4, and sulfuric acid is connected between the storage tank 3 and the electrolytic cell 4. Solution circulation is possible. A pump 32 and a cooler 33 are interposed in this order from the upstream side to the downstream side in the forward path of the electrolysis-side reservoir circulation line 15, and a gas-liquid separator is disposed in the return path of the electrolysis-side reservoir circulation line 15. 26 is interposed. An exhaust gas line 30 and an exhaust gas treatment device 31 are connected to the gas separation side of the gas-liquid separator 26.

Next, the operation of the sulfuric acid solution supply system shown in FIG. 2 will be described.
The washing tank 2a is filled with a sulfuric acid solution having a sulfuric acid concentration of 70 to 96% by mass, and the use side circulation line and the use side with a circulation flow rate of 1/2 to 1/3 V / min with respect to the tank volume V of the washing tank 2a. The sulfuric acid solution is circulated through the storage part circulation line and the electrolytic side storage part circulation line. At this time, the electrolytic cell 4 is energized between the anode and the cathode, and the sulfuric acid solution passed through the electrolytic cell 4 is electrolyzed to obtain a sulfuric acid electrolytic solution. The washing tank 2a is filled with a sulfuric acid electrolyte having a predetermined persulfuric acid concentration by circulation of the sulfuric acid solution, and the sulfuric acid electrolyte is heated to 120 ° C. to 150 ° C. by the heater 2b.

  The sulfuric acid solution in the cleaning tank 2a is drained through the common drain line 10 by the pump 20 along with the circulation. The sulfuric acid solution drained to the common drain line 10 captures solid content such as resist by the washing machine side filter 21, and the sulfuric acid solution from which this solid content has been removed reaches the branch point 10a.

At the branch point 10 a, a part of the sulfuric acid solution flows into the use side circulation connection line 11, and the remaining part flows into the forward path of the use side reservoir circulation connection line 14. At this time, the flow rate of the use side circulation connection line 11 is adjusted by the flow rate adjustment valve 22 and is adjusted by the flow rate adjustment valve 24 of the use side reservoir circulation connection line 14, and the flow rate of each line is adjusted to a predetermined amount. . Thereby, it is possible to avoid the occurrence of problems such as a shortage of the flow rate of one line after branching. In this embodiment, the flow rate adjusting valve is provided in each line, but it may be provided only in the use side circulation connection line 11.
Moreover, it may replace with what adjusts a flow volume and what uses what adjusts flow resistance, such as an orifice, may be used.

A suitable amount of sulfuric acid solution that has flowed into the forward path of the use-side reservoir circulation connection line 14 at the branch point 10 a passes through the flow rate adjustment valve 24, is forcibly cooled by the cooler 25, and is introduced to the liquid inlet side of the reservoir 3. The In the cooler 25, the sulfuric acid solution is forcibly cooled to 10 to 80 ° C., for example.
Further, in the storage tank 3, the sulfuric acid solution is discharged by the pump 32 through the electrolytic side storage part circulation line 15, and the sulfuric acid solution is at a temperature suitable for electrolysis in the electrolytic cell 4 by the cooler 33, for example, 30 ° C. to 70 ° C. Forcibly cool.

  In the electrolytic cell 4, electrolysis is performed while a sulfuric acid solution is passed between the anode and the cathode that are energized by the power supply device, and persulfuric acid is generated in the sulfuric acid solution. The sulfuric acid solution containing persulfuric acid is drained from the drain side of the electrolysis cell 4, and the gas generated by electrolysis is separated by the gas-liquid separator 26. The separated exhaust gas is sent to the exhaust gas treatment device 31 through the exhaust gas line 30 to be subjected to exhaust gas treatment.

The sulfuric acid electrolyte from which the gas has been separated is returned to the storage tank 3 through the return path of the electrolysis-side storage unit circulation line 15. By repeating this, the concentration of persulfuric acid in the sulfuric acid electrolyte in the storage tank 3 is increased.
The sulfuric acid electrolyte in the storage tank 3 is taken out by the pump 27 through the return path of the use-side storage section circulation connection line 14 and sent to the junction 13a. At this time, the sulfuric acid electrolyte side filter 28 captures and removes solids such as fine particles in the sulfuric acid electrolyte and sulfur precipitates generated by the electrolysis from the sulfuric acid solution.
The sulfuric acid electrolyte sent to the junction 13a through the return path of the use-side reservoir circulation connection line 14 joins the sulfuric acid solution fed through the use-side circulation connection line 11 at the junction 13a, and then supplied to the common point. It is introduced into the washing tank 2a through the line 13 and used again for washing.

  The semiconductor wafer that has been cleaned in the cleaning machine 2 is rinsed in a high-temperature rinse bath and a normal-temperature rinse bath, and then dried in a drier to finish the process.

(Embodiment 3)
In the first and second embodiments, when the length of the use side circulation connection line 11 is 1 m or less, the flow resistance of the use side circulation connection line 11 becomes extremely small, and the sulfuric acid solution flows backward. There is a fear. For this reason, it is desirable to provide a check valve in the use side circulation connection line 11.
FIG. 3 shows an example in which a check valve 23 is interposed in the use-side circulation connection line 11 in the system of FIG. A check valve 23 is interposed in the use-side circulation connection line 11 on the downstream side of the flow rate adjustment valve 22. As a result, even when a pulsating flow is generated by the pump 27, the sulfuric acid solution is prevented from flowing back from the junction 13a side to the branch point 10a side in the use side circulation connection line 11, and a normal flow flows under normal conditions. Can do. In FIG. 3, the other configuration is the same as that of the system of FIG. In the system shown in FIG. 2, the check valve 23 can also be interposed in the use-side circulation connection line 11 on the downstream side of the flow rate adjustment valve 22.

  In each of the above embodiments, the cleaning system in which the use side is the batch type cleaning machine 2 has been described, but the use side is not limited to this. The use side should just use the electrolyzed sulfuric acid solution for a predetermined process.

  As mentioned above, although this invention was demonstrated based on the said embodiment, this invention is not limited to description of the said embodiment, A suitable change is possible unless it deviates from the scope of the present invention.

Next, examples of the present invention will be described in comparison with comparative examples.
(Example)
Using the cleaning system shown in FIG. 2, an ashless silicon wafer was cleaned as an electronic material substrate, and the voltage between the anode and the cathode in the electrolytic cell was measured.
Moreover, the same test was done using the conventional system shown in FIG. 6 as a comparative example.
The test conditions are as follows.
Wafer size: 150 mm diameter
Dopant element: Boron dose: 5 × 10 ¹⁴ atoms / cm ²
Resist coating thickness: 1.7 μm
Number of sheets processed at one time: 50 sheets / lot Number of processes per hour: 4 lots / hour to 6 lots / hour Processing temperature in the washing tank: 140 ° C.
Used sulfuric acid solution: Electronics industry grade 96% sulfuric acid to 85% by mass sulfuric acid
Diluted solution For each filter, MF having a housing of PFA and a filter body of PTFE and having a pore diameter of 0.02 μm was used.

FIG. 4 is a graph showing the relationship between the elapsed time from the start of system operation and the inter-electrode voltage in the electrolysis cell obtained for each of the cleaning systems of the above examples and comparative examples.
In the graph, the horizontal axis represents the elapsed time [hrs] from the start of operation, and the vertical axis represents the interelectrode voltage [V] between the anode and the cathode in the electrolysis cell. In addition, t ₁ to t ₁₁ on the horizontal axis indicate the time when the wafer is put into the cleaning tank.

As shown in FIG. 4, in the comparative example, at time t _s after 4 washing process of the lot is completed, the inter-electrode voltage exceeds the allowable voltage becomes electrolytic cell abnormalities in the electrolytic cell, electrolysis in the electrolytic cell by the safety device Stopped. On the other hand, in the examples, the voltage between the electrodes in the electrolysis cell was stable, and the wafer could be cleaned continuously and stably. As described below, the difference between the two is that the common drainage line, the use-side circulation connection line branched from the common drainage line and the use-side reservoir circulation connection line differ in the position of the filter. It is thought to be due to.

  First, in the comparative example, the common drainage line branches into the use side circulation connection line and the use side storage section circulation connection line before the MF having a smaller average pore diameter interposed in the use side circulation connection line. is doing. For this reason, the resist piece transferred to the sulfuric acid solution from the wafer cleaned in the cleaning tank flows into the electrolytic cell and adheres to the cathode. As a result, the interelectrode voltage required for electrolysis in the electrolysis cell increases. If the next wafer cleaning process is performed without increasing the voltage after the interelectrode voltage increases, the resist piece further flows into the electrolytic cell. When several wafer cleaning processes are performed, the amount of resist pieces adhering to the cathode of the electrolytic cell increases, and the voltage between the electrodes gradually increases. Eventually, the upper limit value (alarm value) of the interelectrode voltage set for safety in the electrolytic cell was exceeded, and the electrolytic cell became abnormal, and the apparatus was stopped.

On the other hand, in the example, since it is branched into the use side circulation connection line and the use side reservoir circulation connection line downstream of the MF interposed in the common drainage line, it was washed in the washing tank. The resist piece transferred from the wafer to the sulfuric acid solution is not captured by the MF interposed in the common drain line and flows into the electrolytic cell. The resist pieces captured by the MF are dissolved in the sulfuric acid solution during the circulation of the sulfuric acid solution. Since the resist piece does not flow into the electrolytic cell, the resist piece does not adhere to the cathode of the electrolytic cell. If the resist piece does not adhere to the cathode, the voltage between the electrodes in the electrolysis cell will not increase significantly. The resist dissolved in the sulfuric acid solution during the wafer cleaning processing time (10 to 15 minutes) is decomposed into carbon dioxide and water by sulfuric acid radicals and OH radicals generated by thermal decomposition in the cleaning tank. The voltage between the electrodes at the point decreases.
In the embodiment, the voltage between the electrodes in the electrolysis cell once increases immediately after the wafer cleaning process, but the voltage between the electrodes immediately decreases and the voltage between the electrodes continues to increase even if the next lot is processed. There wasn't.
From the comparison between the above example and the comparative example, if the resist piece does not flow into the electrolytic cell, the voltage between the electrodes in the electrolytic cell does not continue to rise, and the wafer cleaning process can be performed continuously and stably. It was confirmed that it was possible.

DESCRIPTION OF SYMBOLS 1 Sulfuric acid solution supply system 1a Sulfuric acid solution supply system 2 Batch type washing machine 2a Washing tank 3 Reservoir 4 Electrolysis cell 10 Common drainage line 10a Branch point 11 Use side circulation connection line 12 Electrolysis side circulation connection line 13 Common supply line 13a Junction point 14 Use side reservoir circulation connection line 15 Electrolysis side reservoir circulation connection line 21 Washer side filter 22 Flow rate adjustment valve 23 Check valve 24 Flow rate adjustment valve 25 Cooler 28 Sulfuric acid electrolyte side filter 100 Semiconductor wafer

Claims (11)

In the sulfuric acid solution supply system that supplies the electrolyzed sulfuric acid solution to the use side,
A cooling means for cooling the sulfuric acid solution;
An electrolyzer for electrolyzing the sulfuric acid solution;
An electrolytic side circulation line for returning the sulfuric acid solution used on the usage side to the usage side through the cooling means and the electrolysis device in this order;
A use side circulation line for returning the sulfuric acid solution used on the use side to the use side without passing through the cooling means,
The electrolysis side circulation line and the use side circulation line have a common common drain line through which the sulfuric acid solution drained from the use side flows, and are at the downstream end of the common drain line. Each branch from the branch point,
The sulfuric acid solution supply system, wherein the common drain line is provided with a filter that captures solids in the sulfuric acid solution. In the sulfuric acid solution supply system that supplies the electrolyzed sulfuric acid solution to the use side,
A cooling means for cooling the sulfuric acid solution;
A reservoir for storing the sulfuric acid solution;
An electrolyzer for electrolyzing the sulfuric acid solution;
A use side storage section circulation line for returning the sulfuric acid solution used on the use side to the use side through the cooling means and the storage section in this order;
A use side circulation line for returning the sulfuric acid solution used on the use side to the use side without passing through the cooling means and the storage unit;
An electrolytic side reservoir circulation line for returning the sulfuric acid solution discharged from the reservoir to the reservoir via the electrolyzer,
The use side reservoir circulation line and the use side circulation line have a common common drain line through which the sulfuric acid solution drained from the use side flows, and the downstream end of the common drain line Each branch from the branch point at
The sulfuric acid solution supply system, wherein the common drain line is provided with a filter that captures solids in the sulfuric acid solution.   The functional solution supply system according to claim 1, further comprising a flow path resistance adjusting unit or a flow rate adjusting unit in the use side circulation line downstream of the branch point.   4. The functional solution supply system according to claim 3, wherein the flow path resistance adjusting means or the flow rate adjusting means is a valve, check or orifice interposed in the use side circulation line.   The flow path resistance adjusting means or flow rate adjusting means provided in the use side circulation line branching from the branch point of the common drainage line is used as a first flow path resistance adjusting means or flow rate adjusting means to branch from the branch point. The sulfuric acid solution supply system according to claim 3 or 4, wherein a second flow path resistance adjusting means or a flow rate adjusting means is provided in another circulation line.   The use side circulation line and the other circulation line for returning the sulfuric acid solution to the use side have a common common supply line for supplying the sulfuric acid solution to the use side, and the upstream end of the common supply line And the length of the use side circulation line between the junction and the branch point is 1 m or less, and the use side circulation line extends from the junction to the branch point. A sulfuric acid solution supply system according to any one of claims 1 to 5, wherein a check valve is provided to prevent liquid flow toward the water.   The functional solution supply system according to claim 1, wherein the filter has a pore diameter of 0.01 to 10 μm.   The filter provided in the common drainage line is used as a first filter, is another circulation line branched from the branch point, and is equal to the pore diameter of the first filter on the downstream side of electrolysis by the electrolyzer. The sulfuric acid solution supply system according to any one of claims 1 to 7, wherein a second filter having a pore diameter smaller than that of the first filter and having a pore diameter of 0.01 to 10 µm is provided.   9. The use part according to claim 1, wherein the use side is a cleaning part for cleaning an electronic material substrate that has not undergone a pretreatment process in which a resist by pattern processing is attached and the resist is oxidized and incinerated in advance. The sulfuric acid solution supply system according to claim 1. In the sulfuric acid solution supply method of supplying the electrolyzed sulfuric acid solution to the use side,
Step A for branching the sulfuric acid solution used on the use side and electrolyzing a part of the sulfuric acid solution after forced cooling, and circulating the sulfuric acid solution after the electrolysis back to the use side;
A step B in which the remaining branched portion of the sulfuric acid solution used on the use side is circulated back to the use side without forced cooling, and
In the step A and the step B, the sulfuric acid solution from the use side is passed through a filter before branching, thereby capturing the solid matter in the sulfuric acid solution. In the sulfuric acid solution supply method of supplying the electrolyzed sulfuric acid solution to the use side,
Branching the sulfuric acid solution used on the use side and storing a part of the sulfuric acid solution in the storage part after forcibly cooling, draining the sulfuric acid solution from the storage part and circulating it back to the use side; and
Step D of circulating the remaining part of the branched sulfuric acid solution used on the use side back to the use side without forced cooling; and
A step E of draining and electrolyzing the sulfuric acid solution from the storage unit storing the sulfuric acid solution, and circulating the sulfuric acid solution after the electrolysis back to the storage unit,
A method of supplying a sulfuric acid solution, wherein the solid matter in the sulfuric acid solution is captured by passing the sulfuric acid solution from the use side through the filter before branching in the step C and the step D.

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