CN120814031A - Substrate processing apparatus and substrate processing method - Google Patents

Abstract

The present invention provides a technique for efficiently improving the cleanliness of a treatment liquid in a circulation system. The substrate processing apparatus includes a container for storing a processing liquid, a circulation line connected to the container, a pump provided to the circulation line for driving the processing liquid to circulate in a circulation circuit constituted by the container and the circulation line, a heater for heating the processing liquid flowing in the circulation line, a first filter for filtering the processing liquid flowing in the circulation line, a processing unit for processing a substrate using the processing liquid supplied from the circulation line, a filtration line for taking out a part of the processing liquid circulating in the circulation circuit from the circulation circuit and allowing the taken-out processing liquid to flow in a manner of returning to the circulation circuit, a cooler provided to the filtration line for cooling the processing liquid flowing in the filtration line, and at least 1 second filter provided on a downstream side of the cooler of the filtration line for filtering the processing liquid cooled by the cooler before the processing liquid returns to the circulation circuit.

Description

Substrate processing apparatus and substrate processing method

Technical Field

The present invention relates to a substrate processing apparatus and a substrate processing method.

Background

In the manufacture of semiconductor devices, it is necessary to perform liquid treatment using a treatment liquid (chemical liquid, rinse liquid, or the like) on a substrate such as a semiconductor wafer. Before drying the substrate after the liquid treatment, the rinse liquid on the surface of the substrate is replaced with IPA (isopropyl alcohol). Then, spin-drying treatment or supercritical drying treatment is performed on the substrate. The cleanliness of the IPA that covers the substrate surface just prior to drying has a large impact on the amount of particles after drying.

Patent document 1 discloses a treatment liquid supply source (treatment liquid supply mechanism) which is improved in order to improve the cleanliness of IPA. The treatment liquid supply source includes a storage container for storing IPA, a first circulation line connected to the storage container, and a first filter provided in the first circulation line. IPA is supplied to a plurality of processing units via a plurality of supply lines branched from a first circulation line. The treatment liquid supply source further has a second circulation line branched from the first circulation line at a branching point on the first circulation line, and a second filter provided to the second circulation line. The second recycle line returns the IPA to the vessel.

The second circulation line has a shorter flow path length than the first circulation line. The flow rate of the IPA flowing into the second circulation line is smaller than the flow rate of the IPA flowing into the first circulation line downstream of the branching point. The second filter has a smaller filtration amount per unit time than the first filter. Therefore, the contaminant that cannot be captured by the first filter can be captured by the second filter, and as a result, the cleanliness of the IPA located in the circulation system can be improved.

Prior art literature

Patent literature

Patent document 1 International publication No. 2022/009661

Disclosure of Invention

The invention provides a technology for efficiently improving the cleanliness of a treatment liquid in a circulation system.

According to one embodiment of the present invention, there is provided a substrate processing apparatus including a container for storing a processing liquid, a circulation line connected to the container, a pump provided to the circulation line for driving the processing liquid to circulate in a circulation circuit constituted by the container and the circulation line, a heater provided to the circulation line for heating the processing liquid flowing in the circulation line, a first filter provided to the circulation line for filtering the processing liquid flowing in the circulation line, a processing unit for performing processing on a substrate using the processing liquid supplied from the circulation line, a filtration line for taking out a part of the processing liquid circulating in the circulation circuit from the circulation circuit and allowing the taken-out processing liquid to flow back to the circulation circuit, a cooler provided to the filtration line for cooling the processing liquid flowing in the filtration line, and at least 1 second filter provided to the filtration line for filtering the processing liquid before the filtration liquid is circulated by the cooler.

According to the present invention, the cleanliness of the IPA located in the circulation system can be improved efficiently.

Drawings

FIG. 1 is a diagrammatic cross-sectional view of a substrate processing system of one embodiment of a substrate processing apparatus.

Fig. 2 is a schematic longitudinal sectional view showing the structure of a processing unit included in the substrate processing system shown in fig. 1.

Fig. 3 is a piping structure diagram showing a configuration of a treatment liquid supply source (treatment liquid supply means) for supplying IPA as a treatment liquid to the treatment liquid supply portion of the treatment unit shown in fig. 2.

Fig. 4 is a schematic diagram schematically showing the same structure as the embodiment of fig. 3 for explaining the reference of the modified embodiment.

Fig. 5 is a schematic diagram showing a first modified embodiment.

Fig. 6 is a schematic diagram showing a second modified embodiment.

Fig. 7 is a schematic diagram showing a third modified embodiment.

Fig. 8 is a schematic diagram showing a fourth modified embodiment.

Fig. 9 is a schematic diagram showing a modification of the cooler.

Fig. 10 is a graph for explaining the experimental results.

Detailed Description

Hereinafter, preferred and non-limiting embodiments will be described with reference to the accompanying drawings.

[ Outline of substrate processing System ]

A schematic configuration of a substrate processing system 1 (an example of a liquid processing apparatus) according to an embodiment will be described with reference to fig. 1. Fig. 1 is a diagram showing a schematic configuration of a substrate processing system 1 according to an embodiment. In the following, in order to clarify the positional relationship, an X axis, a Y axis, and a Z axis orthogonal to each other are defined, and the positive Z axis direction is defined as the vertical upward direction.

As shown in fig. 1, a substrate processing system 1 includes an infeed and outfeed station 2 and a processing station 3. The infeed and outfeed station 2 is arranged adjacent to the processing station 3.

The carry-in/carry-out station 2 includes a carrier loading section 11 and a conveying section 12. A plurality of carriers C, which house a plurality of substrates in a horizontal state, in the embodiment, semiconductor wafers W (hereinafter, referred to as wafers W) can be mounted on the carrier mounting portion 11.

The transport section 12 is provided adjacent to the carrier mounting section 11, and includes a substrate transport device 13 and a transfer section 14. The substrate transport apparatus 13 includes a wafer holding mechanism that holds a wafer W. The substrate transport apparatus 13 is capable of moving in the horizontal direction and the vertical direction and rotating about a vertical axis, and transports the wafer W between the carrier C and the transfer section 14 using the wafer holding mechanism.

The processing station 3 is disposed adjacent to the conveying section 12. The processing station 3 comprises a conveyor section 15 and a plurality of processing units 16. The plurality of processing units 16 are arranged in a row on both sides of the conveying section 15.

The transport section 15 internally includes a substrate transport device 17. The substrate transport apparatus 17 includes a wafer holding mechanism that holds a wafer W. The substrate transfer device 17 is capable of moving in the horizontal direction and the vertical direction and rotating about a vertical axis, and transfers the wafer W between the transfer section 14 and the processing unit 16 using the wafer holding mechanism.

The processing unit 16 performs substrate processing on the wafer W conveyed by the substrate conveying device 17. The processing unit 16 holds the transported wafer, and performs substrate processing on the held wafer. The processing unit 16 supplies a processing liquid to the held wafer to perform substrate processing.

The treatment liquid is a CF-based cleaning liquid such as HFC (HydroFluoroCarbon: hydrofluorocarbon) for treating the wafer W, or a cleaning liquid such as DHF (Diluted HydroFluoric acid: dilute hydrofluoric acid) for cleaning the residue of the wafer W. The treatment liquid is a rinse liquid such as DIW (DeIonized Water: deionized water) or a substitution liquid such as IPA (IsoPropyl Alcohol: isopropyl alcohol).

In addition, the substrate processing system 1 includes a control device 4. The control device 4 is, for example, a computer, and includes a control unit 18 and a storage unit 19. The storage unit 19 stores therein a program for controlling various processes performed in the substrate processing system 1. The control section 18 controls the operation of the substrate processing system 1 by reading and executing the program stored in the storage section 19.

Further, the program may be recorded in a computer-readable storage medium, and installed from the storage medium to the storage section 19 of the control device 4. Examples of the computer-readable storage medium include a Hard Disk (HD), a Flexible Disk (FD), an optical disk (CD), a magneto-optical disk (MO), and a memory card.

In the substrate processing system 1 configured as described above, first, the wafer W is taken out from the carrier C placed on the carrier placement unit 11 by the substrate transport device 13 that is fed into the send-out station 2, and the taken-out wafer W is placed on the transfer unit 14. The wafer W placed on the transfer section 14 is taken out from the transfer section 14 by the substrate transport apparatus 17 of the processing station 3, and is sent to the processing unit 16.

After the wafer W fed into the processing unit 16 is subjected to the substrate processing by the processing unit 16, the wafer W is fed out from the processing unit 16 by the substrate conveying device 17 and placed on the transfer section 14. Then, the processed wafer W placed on the transfer section 14 is returned to the carrier C of the carrier placement section 11 by the substrate transport apparatus 13.

[ Outline of processing Unit ]

Next, an outline of the processing unit 16 will be described with reference to fig. 2. Fig. 2 is a schematic diagram showing the structure of the processing unit 16 according to the embodiment. The processing unit 16 includes a chamber 20, a substrate holding mechanism 30, a processing liquid supply section 40, and a recovery cup 50.

The chamber 20 houses the substrate holding mechanism 30, the processing liquid supply section 40, and the recovery cup 50. An FFU (FAN FILTER Unit: blower Filter Unit) 21 is provided at the top plate of the chamber 20. The FFU21 creates a vertical laminar flow within the chamber 20.

The substrate holding mechanism 30 includes a holding portion 31, a pillar portion 32, and a driving portion 33. The holding portion 31 holds the wafer W horizontally. The pillar portion 32 is a member extending in the vertical direction, and the base end portion is rotatably supported by the driving portion 33 and horizontally supports the holding portion 31 at the tip end portion. The driving unit 33 rotates the pillar 32 about the vertical axis.

The substrate holding mechanism 30 rotates the support portion 32 by the driving portion 33, thereby rotating the holding portion 31 supported by the support portion 32. Then, the wafer W held by the holding portion 31 rotates.

The processing liquid supply unit 40 supplies the processing liquid to the wafer W. The processing liquid supply unit 40 is connected to a processing liquid supply mechanism (also referred to as a "processing liquid supply source") 70. The treatment liquid supply section 40 includes a plurality of nozzles. For example, a plurality of nozzles are provided corresponding to the respective processing liquids. Each nozzle discharges the processing liquid supplied from each processing liquid supply mechanism 70 to the wafer W.

The recovery cup 50 is disposed so as to surround the holding portion 31, and collects the processing liquid scattered from the wafer W by the rotation of the holding portion 31. A drain port 51 is formed in the bottom of the recovery cup 50, and the treatment liquid collected in the recovery cup 50 is discharged from the drain port 51 to the outside of the treatment unit 16. Further, an exhaust port 52 for exhausting the gas supplied from the FFU21 to the outside of the process unit 16 is formed at the bottom of the recovery cup 50.

[ Structure of IPA supply mechanism ]

Next, the structure of an IPA supply mechanism (hereinafter referred to as "IPA supply mechanism 70") among the processing liquid supply mechanisms 70 will be described with reference to fig. 3. The other processing liquid supply mechanism may have the same or substantially the same configuration as the IPA supply mechanism 70, or may have another configuration known in the field of semiconductor manufacturing apparatuses (particularly, liquid processing apparatuses).

Fig. 3 shows an example in which the IPA supply mechanism 70 supplies IPA to the 2 processing liquid supply units 40 (specifically, for example, the IPA supply nozzles provided in the 2 processing units 16, respectively). The IPA supply mechanism 70 may supply the IPA to 3 or more processing liquid supply units 40, or may supply the IPA to only one processing liquid supply unit 40.

The IPA supply mechanism 70 includes a container (tank) 71, a treatment liquid replenishing portion 72, a drain line 73, a circulation line 74, a filter line 75, a supply line 76, and a return line 77.

The container 71 stores IPA. The processing liquid replenishing unit 72 supplies new IPA to the container 71 when the IPA in the container 71 is to be replaced or when the IPA in the container 71 is smaller than a predetermined amount. In the case where the IPA of the container 71 is to be replaced, the drain line 73 discharges the IPA from the container 71 to the outside.

A pump 80, a heater 81 which is a heating device (heating device on the line), a temperature sensor 82, a first filter 83, a flow meter 84, and a back pressure valve 85 are provided in this order from the side (upstream side) near the container 71 in the circulation line 74.

The pump 80 pumps the IPA through the circulation line 74, thereby forming a circulation flow of the IPA flowing out from the tank 71 to the circulation line 74, flowing through the circulation line 74, and returning to the tank 71. That is, a circulation circuit is formed by the tank 71 and the circulation line 74, and the IPA circulates in the circulation circuit.

The heating amount of the heating device 81 serving as an electric heater is controlled by the control device 4 (see fig. 1), for example, so that the temperature of the IPA flowing in the circulation line 74 detected by the temperature sensor 82 becomes a predetermined temperature. Thus, the temperature of the IPA flowing through the circulation line 74 is maintained at a predetermined temperature (for example, a temperature of about 50 ℃ to 70 ℃).

The flow meter 84 measures and monitors the flow rate of the IPA flowing in the circulation line 74.

A plurality of (the same number as the number of the processing units 16) supply lines 76 are connected to a region of the circulation line 74 on the upstream side of the back pressure valve 85. The IPA taken out from the circulation line 74 via the supply line 76 is supplied to the treatment liquid supply portion 40 (specifically, a nozzle for IPA discharge) of the treatment unit 16.

The back pressure valve 85 functions to stably maintain the pressure on the upstream side of the back pressure valve 85 (i.e., the pressure of the region of the circulation line 74 to which the supply line 76 is connected) at a predetermined value. This can stably control the flow rate of the IPA flowing into each supply line 76.

In the processing unit 16, for example, a chemical solution process is performed on the wafer W, and then a rinse process is performed. After the rinsing process, IPA is supplied to the wafer W through the processing liquid supply unit 40, whereby the rinse liquid (e.g., DIW (pure water)) on the wafer W is replaced with IPA. Thereafter, the wafer W is subjected to spin-drying. Or the wafer W with the IPA liquid film formed on the surface is transported from the processing unit 16 to a supercritical drying processing unit (not shown) and subjected to supercritical drying processing. Regardless of the type of drying process applied, the cleanliness of the IPA supplied immediately before drying the wafer W is very important in improving the cleanliness of the wafer W after drying.

In addition, in the case where the final drying of the wafer W is performed by the supercritical drying processing unit, some of the processing units 16 shown in fig. 1 are liquid processing units, and others are supercritical drying processing units. In the supercritical drying process unit, a supercritical fluid (e.g., supercritical CO ₂) is supplied into the supercritical chamber, and the IPA liquid film on the wafer W is replaced with the supercritical fluid, and then the inside of the supercritical chamber is brought to normal pressure, thereby drying the wafer W. The structure and function of the supercritical drying unit are well known in the art of manufacturing semiconductor devices, and thus detailed description thereof will be omitted.

The supply line 76 is provided with a flowmeter 100, a constant pressure valve 101, a filter 102, and an on-off valve 103.

The control device 4 adjusts the set pressure of the constant pressure valve 101 based on the deviation of the actual flow rate of the IPA detected by the flow meter 100 from the target flow rate, and thereby controls the flow rate of the IPA discharged from the treatment liquid supply unit 40 (nozzle for discharging the IPA) to be the target flow rate. That is, in this case, the constant pressure valve 101 functions as a flow control valve.

The return line 77 is set at a branching point 79 of the supply line 76 between the filter 102 and the on-off valve 103, and branches from the supply line 76. Each return line 77 is provided with an on-off valve 110.

The plurality of return lines 77 merge into a single return line (for convenience of explanation, this is also referred to as "main return line 78") on the downstream side of the on-off valve 110. The downstream end of the main return line 78 is connected to the vessel 71. The main return line 78 is provided with a temperature sensor 111 for measuring the temperature of the IPA flowing through the main return line 78. In the case where there are only 1 return lines 77 in the IPA supply mechanism 70, of course, the downstream ends of the 1 return lines 77 are connected to the container 71.

By switching the opening/closing of the on/off valve 103 of the supply line 76 and the on/off valve 110 of the branch line 77, it is possible to switch between a first state (the on/off valve 110 is closed, the on/off valve 103 is opened, and the on/off valve 103 is closed) in which the IPA flowing into the supply line 76 is supplied from the processing liquid supply portion 40 to the substrate W, and a second state (the on/off valve 110 is opened, the on/off valve 103 is closed), in which the IPA flowing into the supply line 76 is returned to the container 71 through the return line 77.

In the normal operation of the substrate processing system 1 (here, when processing is performed in accordance with a predetermined processing schedule in each processing unit 16), the IPA after the temperature adjustment is always circulated in the circulation line 74, and the on-off valve 110 and the on-off valve 103 are in either the first state or the second state. That is, when no IPA is supplied from the processing liquid supply portion (IPA nozzle) 40 to the wafer W, the IPA flowing into the supply line 76 from the circulation line 74 is returned to the container 71 through the return line 77 and the main return line 78. This suppresses a decrease in the temperature of the piping of the supply line 76.

At a branching point 86 set in the circulation line 74, the filtration line 75 branches from the circulation line 74. In the embodiment shown in fig. 3, the downstream end of the filter line 75 is directly connected to the vessel 71.

The filter line 75 includes, in order from the upstream side, a cooler 90, a temperature sensor 91, a flow rate control valve 92, at least 1 second filter 93, and a flow meter 94. Although not shown, an on-off valve may be provided near the upstream end of the circulation line 74 (upstream side of the cooler 90) in order to isolate the filter line 75 from the circulation line 74. The arrangement order of the apparatuses 90, 91, 92, 93, 94 is not limited thereto, as long as the IPA passes through the second filter 93 after being cooled by the cooler 90.

The cooler 90 cools the IPA passing through the cooler 90. For example, as schematically shown in fig. 3, the cooler 90 includes a cooling medium container 90a storing a cooling medium CM (e.g., water), and a heat exchanging portion 90b immersed in the cooling medium stored in the cooling medium container 90 a. The heat exchange portion 90b is formed of, for example, a stainless steel tube wound in a spiral shape. On the inner peripheral surface of the stainless steel pipe, which is in contact with IPA flowing inside the stainless steel pipe, a resin coating is applied to prevent metal ions from eluting from the inner peripheral surface into the IPA.

The heat exchange portion 90b of the cooler 90 may be made of a resin material (resin pipe). However, since the resin material has poor thermal conductivity and water permeability, water may be mixed into IPA when water is used as a cooling medium in the cooling medium container 90a, which may deteriorate the particle level at the time of wafer drying. Therefore, the heat exchange portion 90b is preferably formed of a metal material.

In one embodiment, the cooling medium CM supplied from the cooling medium supply mechanism 90c is supplied into the cooling medium container 90a through a supply port provided at the bottom of the cooling medium container 90a, and is discharged from the cooling medium container 90a through a discharge port provided at the upper portion of the cooling medium container 90 a. When the cooling medium CM flows in the cooling medium container 90a in this manner, heat exchange is performed between the cooling medium CM and the heated (e.g., 50 to 70 ℃) IPA in the heat exchange portion 90b, whereby the IPA is cooled to a desired temperature. The cooling medium is supplied to the cooling medium supply mechanism 90c from an appropriate cooling medium supply source (for example, a DIW supply source provided as a plant power plant).

In order to adjust the cooling capacity of the cooler 90, the cooling medium supply mechanism 90c may include a device (e.g., a cooling medium cooling apparatus, a flow control valve for adjusting the flow rate of the cooling medium, etc.) that adjusts at least one of the temperature and the flow rate of the cooling medium CM supplied from the cooling medium supply mechanism 90c to the cooling medium container 90 a.

As the flow control valve 92 provided in the filter line 75, a valve of a type having a flow rate adjusting function, for example, a needle valve having a variable opening degree, a constant pressure valve having a variable set pressure, or the like can be used. The mechanism of flow control using the constant pressure valve is the same as that of flow control using the constant pressure valve 101 in the supply line 76.

The flow meter 94 measures the flow rate of the IPA flowing in the filter line 75. Based on the deviation between the actual IPA flow rate and the target IPA flow rate measured by the flow meter 94, the control device 4 can adjust the flow rate of the IPA flowing through the filter line 75 by adjusting the setting of the flow control valve 92 (the set opening of the needle valve, the set pressure of the constant pressure valve), for example. The flow rate adjustment of the IPA can be determined in consideration of the cooling capacity of the cooler 90, the filtering capacity of the second filter 93, and the like (details will be described later).

In the embodiment shown in fig. 3, as "at least 1 second filter", 3 second filters 93 (filter modules) are provided in parallel, and 1 filter group is formed by these 3 second filters 93. By disposing the second filters 93 in parallel, the flow rate of the IPA passing through the 1 filter module 93 can be suppressed low, and the total flow rate of the IPA passing through the filter group can be increased.

Next, a filter included in the IPA supply mechanism 70 will be described.

The first filter 83 provided in the circulation line 74 is passed through which the IPA heated to, for example, 50 to 70 ℃. In order to simultaneously supply the IPA to the plurality of supply lines 76 corresponding to the plurality of processing units 16, the flow rate of the IPA circulated in the circulation line 74 needs to be set to a relatively high value (for example, about 5L/min).

When relatively high-temperature IPA flows through the circulation line 74, materials forming the liquid contact portion of the filter, the heating device, and the like are eluted into the IPA. Such eluted contaminants are difficult to remove only through the first filter 83 at a level that meets the most stringent criteria required in the latest processes. The reasons for this are as follows.

Substances that are completely dissolved in IPA will pass through the filter.

Substances that are not completely dissolved in IPA (e.g. gelatinous substances) deform through the filter under high flow rate and high differential pressure conditions, even if in contact with the filter medium of the filter. In addition, even if the contaminant is temporarily trapped by the filter medium of the filter, it may be detached from the filter medium of the filter under the conditions of high flow rate and high differential pressure.

The filter is able to capture the contaminants not only by physical filtration (capturing particles with a sieve) but also by adsorption (adsorption based on van der waals forces or hydrogen bonding), but the adsorptivity is reduced at high temperatures.

When the IPA containing the contaminant is supplied to the wafer W without being removed, it causes deterioration of particle performance.

The second filter 93 provided in the filter line 75 is provided to remove the contaminant that cannot be removed by the first filter 83 due to the above-described reasons. As described above, the filter removes pollutants by adsorption in addition to physical filtration. By adsorption, it is possible to capture contaminants smaller than or deformable to pass through the mesh holes of the filter medium. In order to sufficiently exert the adsorption effect, it is effective to reduce the temperature of the liquid (IPA) passing through the filter or to reduce the flow rate of the liquid passing through the filter.

In consideration of the above, a part of the IPA having a temperature of about 50 ℃ to 70 ℃ flowing through the circulation line 74 is caused to flow into the filter line 75. In the filter line 75, the IPA is first cooled to a temperature of, for example, 40 ℃ or less by the cooler 90, and then the cooled IPA is passed through the second filter 93. By cooling the IPA, at least a part of the contaminant completely dissolved in the IPA is precipitated, and the deformability of the gel-like contaminant (organic matter) located in the IPA is reduced. Further, by cooling the IPA, the adsorption action of the filter (second filter 93) can be improved (separation from the filter element is suppressed). In this state, by passing the IPA through the second filter 93, the contaminant that cannot be removed by the first filter 83 can be efficiently removed by the second filter 93.

The IPA passing through the second filter 93 contains a relatively large amount of organic matters having hydrophilic groups (hydrophilic groups) or an aggregate thereof as contaminants. From the viewpoint of efficiently adsorbing such contaminants, the filter medium of the second filter 93 is preferably formed of a material having a hydrophilic group (specifically, for example, nylon, polyimide subjected to a hydrophilic treatment, a fluorine-based resin (for example, hydrophilic PTFE), or the like).

In addition, as a filter having the ability to adsorb and remove the above-described contaminant substances (e.g., gel-like substances), most of the filters currently commercially available are low in heat resistant temperature (e.g., around 40 ℃). From this point of view, it is sometimes necessary to provide the cooler 90 in front of the second filter 93. In any case, when the gel-like substance is the removal target, the removal efficiency of the gel-like substance can be improved by lowering the IPA temperature.

In order to improve the removal efficiency of the gel-like contaminant by the second filter 93, it is preferable to perform filtration under low flow rate and low differential pressure conditions. The flow rate of the IPA passing through the 1 second filter 93 is preferably set to be in the range of 50 to 500ml/min (milliliters per minute), for example.

The flow rate Q2 of the IPA flowing in the filter line 75 is preferably sufficiently smaller than the flow rate Q1 of the IPA flowing in the first filter 83 of the circulation line 74 (i.e., the sum of the flow rate of the IPA flowing in the circulation line 74 on the downstream side of the branching point 86 and the flow rate of the IPA flowing in the filter line 75). If the cooled IPA is always returned from the filter line 75 to the container 71 at a large flow rate, the power consumption of the heating device 81 increases, and there is a possibility that the temperature stability of the IPA in the circulation system and the temperature stability of the IPA supplied to the processing unit 16 may be impaired. In the case where a plurality (N) of second filters 93 are provided in parallel, the flow rate of IPA passing through 1 second filter 93 is Q2/N.

In view of the above, as an example, when the flow rate Q1 is set to 5L/min (liters per minute), the flow rate Q2 is set to 500ml/min or less, for example. In this case, it was confirmed that the temperature of the IPA flowing through the filter line 75 can be stably maintained at, for example, about 70 ℃. The appropriate range of the ratio between Q1 and Q2 varies depending on various factors such as the capacity of the heating device 81 and the target temperature of the IPA flowing through the filter line 75, and therefore, the above-mentioned values are merely examples.

The length of the filter line 75 is preferably shorter than the circulation line 74. By shortening the circulation line 75, the frequency of low-temperature filtration of the same volume of IPA is increased, and the filtration efficiency can be improved.

The basic idea will be described below as to how to set the temperature T1 of the IPA supplied to the processing unit 16 (i.e., the temperature of the IPA heated by the heating device 81), the temperature T2 of the IPA passing through the cooler 90 of the filter line 75, and the flow rates Q1 and Q2 described above.

The higher the temperature T1, the greater the amount of contaminant dissolved into the IPA flowing in the recycle line 74.

The lower the temperature T2, the higher the pollutant capturing rate of the second filter 93 when passing through the second filter 93.

The larger the temperature difference between the temperature T1 and the temperature T2 (in other words, the larger the decrease in the IPA temperature in the cooler 90), the larger the power consumption of the heating device 81, and the lower the stability of the temperature of the entire circulation system (in particular, the temperature of the IPA supplied from the circulation line 74 to the treatment liquid supply portion of the treatment unit 16) is likely to be.

The lower the flow Q2, the higher the pollutant capturing rate of the second filter 93 when passing through the second filter 93.

The higher the flow rate Q2 (or the higher the ratio of the flow rate Q2 to the flow rate Q1), the greater the power consumption of the heating device 81, and the lower the stability of the temperature of the entire circulation system (in particular, the temperature of the IPA supplied from the circulation line 74 to the treatment liquid supply portion of the treatment unit 16) is likely to be.

A specific example of the operation in consideration of the above will be described.

When the temperature T1 is about 50 ℃ to 60 ℃ which is relatively low, the amount of the contaminant eluted into the IPA is relatively small. In this case, the temperature T2 may be relatively high, and thus, for example, the temperature T2 may be set to about 40 ℃. The flow rate Q2 may be relatively high.

When the temperature T1 is about 70 ℃ which is relatively high, the amount of contaminants eluted into IPA is relatively large. In this case, in order to sufficiently remove the contaminant, the temperature T2 is preferably relatively low. In this case, the temperature T2 is set to, for example, 30 ℃ or less. In addition, the flow rate Q2 is preferably relatively low.

A function or table (table) indicating the preferred temperature T2 and flow rate Q2 corresponding to the temperature T1 (or the temperature T1 and flow rate Q1) may be stored in the control device 4. In this case, the temperature T2 and the flow rate Q2 may be determined based on the function or the table, and the operation of the cooler 90 (the cooling medium temperature and/or the cooling medium flow rate) and/or the opening degree of the flow control valve 92 may be automatically adjusted. The cooler 90 can always be operated under certain conditions. In this case, the flow rate Q2 may be changed according to the required temperature T2. Such control of the operation conditions can be performed under the control of the control device 4.

When the IPA in use existing in the processing liquid supply mechanism 70 (the container 71 and the respective lines 74, 75, 76, 77, etc. formed by the pipes) is to be replaced with a new (unused) IPA (or when a new substrate processing system 1 is activated), the following operations can be performed. That is, after the start of the circulation of the new IPA by the pump 80 and the temperature adjustment of the new IPA by the heating device 81, the flow rate Q2 may be set to a relatively high first flow rate in a first period before a predetermined time elapses, and the flow rate Q2 may be reduced to a relatively low second flow rate in a second period thereafter. In the first period, although the filtration efficiency (the capturing rate of the contaminant) is relatively low, the filtration volume per unit time can be increased, and therefore the cleanliness of the IPA in the circulation system (for example, in the container) can be improved to the first level in a relatively short time. Then, during the second period, although the filtration volume per unit time is reduced, the filtration can be performed with relatively high filtration efficiency, and therefore the cleanliness of the IPA in the circulation system can be improved to a second level higher than the first level. This can shorten the time required to increase the degree of cleaning of the IPA in the circulation system to the second level, as compared with the case where the flow rate Q2 is set to the second lower flow rate from the first. This operation is enabled with a great advantage of providing the filter line 75 with a flow control valve 92.

When metal ions eluted from the stainless steel pipe (e.g., passing through the coating layer) constituting the heat exchange portion 90b of the cooler 90 become a problem, a filter having a metal ion removing ability, such as a membrane filter, may be used as the second filter 93. There are also membrane filters having the ability to trap the organic substance having a hydrophilic group or an aggregate thereof.

For example, the filter 102 provided in the supply line 76 may be smaller than the first filter 83 provided in the circulation line 74 and may have the same specification as the first filter 83.

According to the above embodiment, a part of the IPA flowing in the circulation circuit constituted by the tank 71 and the circulation line 74 is taken out to the filter line 75, and the taken-out IPA is cooled by the filter line 75, filtered by the second filter 93, and returned to the tank 71. The temporarily cooled IPA is not mixed with the high temperature IPA before being filtered by the second filter 93. Accordingly, it is possible to remove the contaminant (the substance that causes the generation of particles) that cannot be removed in the first filter 83 provided on the circulation line 74 in which the IPA flows at a high temperature and a high flow rate. Accordingly, the degree of cleaning of the IPA flowing through the circulation line 74 is also improved, and as a result, the degree of cleaning of the IPA supplied from the processing liquid supply portion 40 of the processing unit 16 to the wafer W can also be improved.

Further, by providing a plurality of second filters 93 in parallel to the filter line 75, the flow rate of IPA passing through 1 second filter 93 can be suppressed low, and therefore, the contaminant can be removed more reliably. Further, the second filter 93 passing through the relatively low-temperature IPA also dissolves out the contaminants, and the greater the number of the second filters 93, the greater the total amount of contaminants dissolved out. However, since a part of the dissolved contaminants is captured by the second filter 93 and the total amount of contaminants captured by the second filter 93 (contaminants contained in the IPA flowing through the entire circulation system) is larger as the number of the second filters 93 is larger, the number of the second filters 93 is preferably larger. However, considering the cleanliness requirement of the current IPA, it is sufficient that the number of the second filters 93 is about 3 in most cases.

The above-described embodiment and its modified embodiments will be briefly described below with reference to fig. 4 to 8 as schematic drawings.

Fig. 4 is a diagram showing the embodiment shown in fig. 3 in a simplified manner. For easy understanding of the drawings, in fig. 4 to 8, the vessel 71 is labeled "T", the pump 80 is labeled "P", the heater 81 is labeled "H", the first filter 83 is labeled "F1", the back pressure valve 85 is labeled "BPV", the cooler 90 is labeled "C", the flow control valve 92 is labeled "FCV", and the second filter 93 is labeled "F2". Fig. 4 to 8 are not shown in the drawings, which are not directly related to the description.

Fig. 5 shows a first variant embodiment, where the downstream end of the filter line 75 is not connected directly to the tank T (71), but to the circulation line 74. In this case, the filter line 75 is indirectly connected to the container 71 via the circulation line 74. The connection position of the filter line 75 in the circulation line 74 is downstream of the back pressure valve BPV (85) and upstream of the tank T. In the first modified embodiment, the filter line 75 is also provided to take out a part of the processing liquid (IPA) circulating in the circulation circuit (the tank 71+the circulation line 74) and return the taken-out processing liquid (IPA) to the circulation circuit (the circulation line 74 in the example of fig. 5), and this is the same as the embodiment of fig. 4. The first modified embodiment also has the same operational effects as the embodiment of fig. 4.

Fig. 6 shows a second modified embodiment. Here, instead of providing the dedicated filter line 75, a cooler C and a second filter 93 are provided in the main return line 78 (i.e., a portion where the plurality of return lines 77 join to become a single return line). In the second modified embodiment, the supply line 76 (a portion on the upstream side of the branch point 79) and the return line 77 (78) correspond to a filter line that takes out a part of the processing liquid (IPA) circulating in the circulation circuit (the tank 71+the circulation line 74) and makes the taken-out processing liquid (IPA) flow so as to return to the circulation circuit (the tank 71 in the example of fig. 6).

Since the flow rate of the IPA flowing into the return line 77 (78) varies depending on the operating states of the plurality of processing units 16, a problem may occur when the flow rate of the main return line 78 is to be freely reduced. Therefore, in the case where it is desired to adjust the flow rate of the IPA flowing through the second filter 93, a bypass line (see a broken line in fig. 6) may be provided which bypasses the cooler C and the second filter 93 to connect the return line 77 (78) to the tank, and a valve (not shown) having a flow control function may be provided in the return line 77 (78) and/or the bypass line. Alternatively, a number of the second filters 93 may be provided in such a manner that, when the flow rate of the IPA flowing in the main return line 78 reaches the maximum, the flow rate of the IPA passing through each of the second filters 93 is low to such an extent that the desired filtering performance can be achieved.

In this second modified embodiment, too, the low-temperature filtration of IPA is performed in the same manner as in the embodiment of fig. 4, and therefore, the contaminant in IPA can be removed efficiently.

Fig. 7 shows a third modified embodiment, in which not only the downstream end but also the upstream end of the filter line 75 is connected to the tank T (71). That is, in this third modified embodiment, the circulation line 74 and the filter line 75 are formed as circulation circuits independent of each other in portions other than the tank T. In this case, the driving force of the pump P (80) cannot be used to circulate the IPA in the filter line 75. Therefore, the filter line 75 is provided with an additional pump P2 (80) for forming a circulating flow of IPA. The flow rate of the IPA circulated in the filter line 75 may be adjusted by changing the operation condition of the pump P2 alone, or may be controlled by a flow rate control device (not shown) provided in the filter line 75. In the third modified embodiment, compared with other embodiments, the flow rate of the IPA flowing through the filter line 75 is easily and precisely controlled.

In this third modified embodiment, too, the low-temperature filtration of IPA is performed in the same manner as in the embodiment of fig. 4, and therefore, the contaminant in IPA can be removed efficiently.

Fig. 8 shows a fourth variant embodiment, where 2 filter lines 75 are provided. The equipment (90 to 94) provided in each filter line 75 is the same. An on-off valve 95 is preferably provided near the upstream end of the at least one filter line 75. By opening and closing the on-off valve 95, the state in which the IPA is simultaneously flowed through the 2 filter lines 75 and the state in which the IPA is flowed through only the 1 filter line 75 can be switched. According to this configuration, for example, when the cleaning degree of the IPA existing in the circulation system is to be improved in a short time, for example, when the liquid in the container 71 is replaced, the two filter lines 75 are used for filtration, and after the cleaning degree is stabilized, only one filter line 75 is used for filtration.

As a fifth modification not shown, the IPA supply mechanism 70 may include 2 or more of the filter lines 75 (including the filter line(s) common to the return line 77 (78)) shown in fig. 4 (or fig. 5), 6, and 7.

As another modified embodiment, 2 or more coolers 90 (not shown) may be provided in series or in parallel with 1 filter line 75.

As schematically shown in fig. 9, the second filter 93 may be housed in the cooling medium container 90a of the cooler 90 so that not only the heat exchange portion 90b but also the second filter 93 may be cooled by the cooling medium CM. Further, when the cooling medium CM uses water, the member immersed in the water is preferably formed of a metal that does not pass water, or a coating layer formed of a material that does not pass water is provided. In this case, the arrangement order of the various devices (90 to 94, etc.) located in the filter line 75 may be changed within a range where no functional impediment occurs, and for example, the flow control valve 92 may be provided upstream of the heat exchange portion 90b or downstream of the second filter 93.

Examples (example)

The results of the test performed to confirm the effects of the embodiment will be described below.

In the IPA supply mechanism 70 having a configuration substantially similar to that of fig. 3, a bypass line bypassing the equipment from the cooler 90 to the flowmeter 94 was connected to the filter line 75, and a test was performed using such a configuration. A filter having a nominal filtration accuracy of 5nm was used as the first filter, and a filter having a nominal filtration accuracy of 5nm was used as the second filter 93.

The container 71 is filled with new IPA, and the IPA adjusted to 70 ℃ is circulated in the circulation line 74. At this time, the bypass line is opened so that the IPA does not pass through the equipment from the cooler 90 to the flow meter 94. At 1.5hr, 2.5hr, 3hr, 4hr, and 5hr from the start of the cycle, the IPA taken out from the circulation line 74 is supplied from the treatment liquid supply portion 40 (IPA nozzle) of the treatment unit 16 to the wafer W, and thereafter, the wafer W is spin-dried. After drying, particle growth (ADDER PARTICLE) of 13.5nm or more in size existing on the surface of the wafer W was examined. At this time, all of the IPA flowing into the filtration line 75 is flowed into the bypass line, and no low-temperature filtration is performed.

The test results are shown in the graph of fig. 10. From the left half of the graph, the particle increment decreased with time from the start of the cycle, and after 4hr elapsed, the particle increment reached a minimum value and was not further decreased. This can be considered the filtration limit of the first filter 83 of the recycle line 74.

Thereafter, the bypass line of the filter line 75 was cut off, the IPA flowing into the filter line 75 was cooled to 28 ℃ by the cooler 90, and then the IPA was filtered by passing through 3 second filters 93 provided in parallel. The flow rate of IPA through each of the 1 second filters 93 was 0.12L/min. The low-temperature IPA filtered by the second filter 93 is returned to the container 71. At the time of 0.25hr, 0.5hr, 1.5hr, 2hr, and 2.5hr from the time of forming the state, the IPA taken out from the circulation line 74 is supplied from the treatment liquid supply portion 40 (IPA nozzle) of the treatment unit 16 to the wafer W, and thereafter, the spin drying of the wafer W is performed. Then, the particle increment (ADDER PARTICLE) of 13.5nm or more was examined in the same manner as described above.

As is clear from the right half of the graph of fig. 10, the particle increment further decreases with time from the start of low-temperature filtration, and after 2hr, the particle increment reaches the minimum value and does not decrease any further. This can be considered the filtration limit of the second filter 93 of the filter line 75.

The minimum value of the particle increment when the filtration is performed by the first filter 83 alone is 373, and the minimum value of the particle increment when the filtration is performed by the combination of the filtration by the first filter 83 and the low-temperature filtration by the second filter 93 is 192. That is, the minimum of particle increments can be improved by 50%.

In addition, although several tests were performed under the same conditions, it was confirmed that the minimum value of the particle increment could be improved by about 40% to 50% in any case.

When SEM observation of the particles was performed, it was confirmed that the particles derived from the gel-like material were reduced in the case where the filtration of the first filter 83 and the low-temperature filtration of the second filter 93 were performed in combination, as compared with the case where the filtration of the first filter 83 alone was performed.

The embodiments disclosed herein are to be considered in all respects as illustrative and not restrictive. The above-described embodiments may be omitted, substituted, or altered in various ways without departing from the technical aspects and gist of the claimed invention.

In the disclosed embodiment, the treatment liquid to be filtered is IPA, but the treatment liquid is not limited thereto, and may be, for example, an organic solvent (for example, propylene glycol, ethylene glycol, dimethyl sulfoxide, etc.) used in BEOL (back end of line).

The substrate to be processed is not limited to a semiconductor wafer, and may be another type of substrate (base plate) used for manufacturing a semiconductor device such as a glass substrate or a ceramic substrate.

Description of the reference numerals

71. Container

74. Circulation pipeline

80. Pump with a pump body

81. Heater (heating device)

83. First filter

75. 76+77 (78) Filter line

90. Cooling device

93. Second filter

Claims (18)

1. A substrate processing apparatus, comprising:

A container for storing a treatment liquid;

a circulation line connected to the vessel;

A pump provided in the circulation line for driving the treatment liquid to circulate in a circulation circuit constituted by the container and the circulation line;

A heater provided in the circulation line and configured to heat the treatment liquid flowing through the circulation line;

a first filter provided in the circulation line and configured to filter the treatment liquid flowing through the circulation line;

A processing unit that performs a process on a substrate using the processing liquid supplied from the circulation line;

a filtration line that takes out a part of the treatment liquid circulating in the circulation circuit from the circulation circuit and that causes the taken-out treatment liquid to flow so as to return to the circulation circuit;

A cooler provided in the filter line for cooling the treatment liquid flowing through the filter line, and

At least 1 second filter provided on a downstream side of the cooler of the filter line, and configured to filter the treatment liquid cooled by the cooler before the treatment liquid is returned to the circulation circuit.

2. The substrate processing apparatus according to claim 1, wherein,

The upstream end of the filter line is connected to the circulation line, and the downstream end of the filter line is connected to the vessel directly or indirectly via the circulation line.

3. The substrate processing apparatus according to claim 1, wherein,

The device further comprises a flow control valve arranged on the filter pipeline and used for adjusting the flow of the treatment liquid flowing through the filter pipeline.

4. The substrate processing apparatus according to claim 1, wherein,

The second filters are provided in plurality and are arranged in parallel on the filter pipeline.

5. The substrate processing apparatus according to claim 1, wherein,

The cooler includes a metal pipe in which the treatment liquid flows, and a cooling medium container that accommodates a cooling medium that cools the metal pipe from outside,

A resin coating layer for preventing elution of metal components from the metal pipe is provided on the inner surface of the metal pipe.

6. The substrate processing apparatus according to claim 1, wherein,

The treatment liquid is an organic solvent.

7. The substrate processing apparatus according to claim 1, wherein,

The second filter is formed of a resin material having an adsorption effect based on a hydrophilic group or an adsorption effect based on van der Waals force.

8. The substrate processing apparatus according to claim 1, wherein,

The second filter is constituted by a membrane filter having metal removing performance.

9. The substrate processing apparatus according to claim 1, wherein,

The heater heats the treatment liquid to a temperature of 50 ℃ or higher, and the cooler cools the treatment liquid to a temperature of 40 ℃ or lower.

10. The substrate processing apparatus according to claim 1, wherein,

The filter line is directly connected to the container at both ends thereof, and the treatment liquid directly flowing out from the container to the filter line is directly returned to the container.

11. The substrate processing apparatus of claim 1, further comprising:

a supply line connected to the circulation line, configured to enable the treatment liquid taken out from the circulation line to be supplied to the treatment unit via the supply line, and

A return line connected to the supply line, configured to be able to return the processing liquid flowing in the circulation line to the container without being supplied to the processing unit,

The cooler and the at least 1 second filter are provided in the return line, and a series of lines consisting of the supply line and the return line can be used as the filter line.

12. The substrate processing apparatus according to claim 1, wherein,

More than 2 coolers are arranged in series or in parallel on the filter pipeline.

13. The substrate processing apparatus according to claim 1, wherein,

The filter lines are provided with 2 or more, and the 2 or more filter lines are each provided with a cooler and a second filter.

14. The substrate processing apparatus according to claim 1, wherein,

The length of the filter line is shorter than the length of the circulation line.

15. The substrate processing apparatus according to claim 1, wherein,

The filter line is provided with a flow control valve for adjusting the flow rate of the treatment liquid flowing through the second filter.

16. The substrate processing apparatus according to claim 15, wherein,

And control means for controlling at least the operation of the flow control valve,

The control device controls the operation of the flow control valve so that the flow rate of the treatment liquid flowing through the second filter becomes a first flow rate before the amount of the treatment liquid circulating in the circulation circuit decreases to a first amount, and the flow rate of the treatment liquid flowing through the second filter becomes a second flow rate smaller than the first flow rate after the amount of the treatment liquid decreases to the first amount.

17. The substrate processing apparatus according to claim 1, wherein,

The treatment fluid is isopropanol, propylene glycol, ethylene glycol or dimethyl sulfoxide.

18. A substrate processing method using a substrate processing apparatus, wherein,

The substrate processing apparatus includes:

A container for storing a treatment liquid;

a circulation line connected to the vessel;

A pump provided in the circulation line for driving the treatment liquid to circulate in a circulation circuit constituted by the container and the circulation line;

A heater provided in the circulation line and configured to heat the treatment liquid flowing through the circulation line;

a first filter provided in the circulation line and configured to filter the treatment liquid flowing through the circulation line;

A processing unit that performs a process on a substrate using the processing liquid supplied from the circulation line;

a filtration line that takes out a part of the treatment liquid circulating in the circulation circuit from the circulation circuit and that causes the taken-out treatment liquid to flow so as to return to the circulation circuit;

A cooler provided in the filter line for cooling the treatment liquid flowing through the filter line, and

At least 1 second filter provided downstream of the cooler in the filter line, for filtering the treatment liquid cooled by the cooler before the treatment liquid is returned to the circulation circuit,

The substrate processing method comprises the following steps:

a step of heating the treatment liquid to a predetermined temperature by the heater and circulating the treatment liquid in the circulation circuit while filtering the treatment liquid by the first filter;

a step of taking out a part of the treatment liquid circulated in the circulation circuit to the filtration line while circulating the treatment liquid in the circulation circuit;

a step of cooling the treatment liquid taken out to the filter line by a cooler;

A step of filtering the processing liquid cooled by the cooler by a second filter;

A step of returning the treatment liquid filtered by the second filter from the filter line to the circulation circuit and mixing the treatment liquid with the treatment liquid flowing in the circulation circuit, and

And a step of supplying the mixed processing liquid from the circulation line to the processing unit to perform liquid processing on the substrate.