JP4836846B2 - Substrate processing apparatus and substrate processing method - Google Patents

Description

  The present invention relates to a semiconductor wafer, a glass substrate for photomask, a glass substrate for liquid crystal display, a glass substrate for plasma display, a substrate for FED (Field Emission Display), an optical disk substrate, a magnetic disk substrate, a magneto-optical disk substrate, etc. The present invention relates to a substrate processing apparatus and a substrate processing method suitable for a freezing process for freezing a liquid film formed on the surface of various substrates (hereinafter simply referred to as “substrate”).

  Conventionally, a technique of freezing a liquid film by cooling the substrate with the liquid film attached to the surface of the substrate is used as one of the processes for the substrate. In particular, such a freezing technique is used as part of a cleaning process for a substrate. In other words, contaminants such as particles adhering to the substrate surface are removed without collapsing the pattern formed on the substrate surface with the miniaturization, higher functionality, and higher accuracy of devices typified by semiconductor devices. It has become increasingly difficult. Therefore, the contaminants adhering to the substrate surface are removed using the above-described freezing technique as follows.

  First, a liquid is supplied to the substrate surface to form a liquid film on the substrate surface. Subsequently, the liquid film is frozen by cooling the substrate. As a result, a frozen film is generated on the surface of the substrate to which the contaminant is attached. Finally, by removing the frozen film from the substrate surface, contaminants are removed from the substrate surface together with the frozen film.

  Here, as a liquid film freezing method for freezing the liquid film formed on the substrate surface, there are the following methods. For example, in the apparatus described in Patent Document 1, a substrate is accommodated in a processing chamber, and the substrate is supported on a pedestal (pedestal). A removal fluid such as steam or ultrapure water vapor is supplied to the substrate surface. Thereby, a liquid film is formed by the removal fluid on the substrate surface. Subsequently, a cooling gas (refrigerant) having a temperature lower than the freezing temperature of the removed fluid is injected into the processing chamber, and the cooling gas is circulated in the processing chamber. Then, the liquid film on the substrate surface is frozen, and a frozen layer (frozen film) is generated on the substrate surface.

JP-A-3-145130 (FIG. 1)

  By the way, in the apparatus described in Patent Document 1, a cooling gas is injected into the processing chamber and the cooling gas is circulated in the processing chamber to generate a frozen layer on the substrate surface. For this reason, not only the substrate but also a peripheral member located around the substrate including the substrate holding means such as a pedestal (hereinafter simply referred to as “substrate peripheral member”) is cooled to a temperature below or near the freezing temperature by the cooling gas. It will be cooled. As a result, there has been a problem that the peripheral member of the substrate is damaged by cold and the durability of the peripheral member of the substrate is deteriorated.

  The present invention has been made in view of the above problems, and provides a substrate processing apparatus and a substrate processing method capable of generating a frozen film on the substrate surface while suppressing the deterioration of the durability of the substrate peripheral member. With the goal.

The present invention is a substrate processing apparatus suitable for a freezing process for freezing a liquid film formed on a substrate surface, and in order to achieve the above object, a substrate that holds the substrate in a state in which the liquid film is formed on the substrate surface While holding means, a cooling nozzle that locally discharges a coolant having a temperature lower than the freezing point of the liquid constituting the liquid film toward the surface of the substrate held by the substrate holding means, and the cooling nozzle facing the substrate surface A relative movement mechanism that moves relative to the substrate along the substrate surface and a gas that essentially contains oxygen or argon are used as a coolant, and at least a part of oxygen or argon is liquefied by cooling the gas. includes a coolant supply unit for feeding the cooling nozzle, and atomizing means for atomizing the liquid component of the liquefied refrigerant by the refrigerant supply unit, the cooling nozzle is atomized by atomizing means The refrigerant containing liquid component discharged toward the substrate surface, supplying the atomized liquid component in the liquid film on the vaporizing was further cooled gas before reaching the liquid film on the substrate surface, the relative movement mechanism Is characterized in that a frozen film is generated on the surface of the substrate by moving the cooling nozzle that discharges the gas relative to the substrate.

The present invention is also a substrate processing method suitable for a freezing process in which a liquid film formed on a substrate surface is frozen. In order to achieve the above object, the substrate is held in a state in which the liquid film is formed on the substrate surface. While discharging the coolant having a temperature lower than the freezing point of the liquid constituting the liquid film locally from the cooling nozzle toward the surface of the substrate, the cooling nozzle is opposed to the substrate surface in parallel with the discharging step. The relative movement step of moving the substrate relative to the substrate along the substrate surface to generate a frozen film on the substrate surface, and using a gas containing oxygen or argon as a refrigerant and cooling the gas to oxygen or argon comprising of a delivery step of delivering the cooling nozzles in a state of being liquefied at least a portion, and atomization step of atomizing the liquid component of the liquefied refrigerant by sending step, in the discharging step, The refrigerant containing the liquid component atomized by the granulation process is discharged toward the substrate surface, the atomized liquid component is vaporized until it reaches the liquid film on the substrate surface, the gas is further cooled, and the liquid It is characterized by being supplied to the membrane .

  In the invention thus configured (substrate processing apparatus and substrate processing method), the refrigerant having a temperature lower than the freezing point of the liquid constituting the liquid film formed on the substrate surface is locally directed from the cooling nozzle toward the substrate surface. Discharged. Further, the cooling nozzle is moved relative to the substrate along the substrate surface while facing the substrate surface. As a result, a region where the liquid film is frozen (frozen region) in the surface region of the substrate surface is expanded and a frozen film is generated on the substrate surface. Thus, since the supply part of the coolant is limited to a partial region on the substrate surface, it is possible to minimize the temperature decrease of the substrate peripheral member such as the substrate holding means. Therefore, it is possible to generate a frozen film on the substrate surface while suppressing the deterioration of the durability of the substrate peripheral member.

  In the present invention, a gas essentially containing oxygen or argon is used as a refrigerant, and the gas is cooled and sent to the cooling nozzle in a state where at least a part of oxygen or argon is liquefied, and discharged from the cooling nozzle. As a result, even better operational effects can be obtained. Detailed experimental results and the like will be described in detail later. As described above, the refrigerant that is discharged from the cooling nozzle toward the substrate surface is discharged from the cooling nozzle as a refrigerant by using a gas containing oxygen or argon as a refrigerant. The temperature (hereinafter referred to as “discharged refrigerant temperature”) can be lowered. Therefore, the discharged refrigerant temperature is cooled to a temperature suitable for freezing the liquid film without cooling the refrigerant by a cooling device (refrigerant supply unit) so that the discharged refrigerant temperature is lowered to a temperature suitable for freezing the liquid film. It becomes possible to do. Therefore, the load on the cooling device can be reduced.

  Here, the refrigerant supply unit may liquefy at least part of oxygen or argon by cooling the gas by heat exchange between the gas used as the refrigerant and liquid nitrogen. Here, the discharge refrigerant temperature can be lowered to a temperature suitable for freezing the liquid film without cooling the gas so that the discharge refrigerant temperature is lowered to a temperature suitable for freezing of the liquid film. The amount of liquid nitrogen used as the refrigerant can be reduced.

  Further, although oxygen or argon can be used alone as a refrigerant, it is preferable to use a mixed fluid in which oxygen or argon is mixed with nitrogen gas. The boiling point of nitrogen (-195.8 ° C.) is lower than that of oxygen or argon (−183 ° C. and −185.9 ° C., respectively). For this reason, the following effects can be obtained by using a mixed fluid in which oxygen gas or argon is mixed with nitrogen gas. That is, when oxygen or argon is used alone, the amount of refrigerant supplied to the substrate surface in a liquefied state increases, and it becomes difficult to freeze the liquid film well. On the other hand, by using a mixed fluid in which oxygen or argon is mixed with nitrogen gas, it is possible to liquefy only oxygen or argon while nitrogen is in a gaseous state and send it to the cooling nozzle. Thereby, it can suppress that a liquid component (liquefied oxygen or argon) is supplied to the substrate surface, and can freeze a liquid film favorably.

  Further, atomization means for atomizing the liquid component of the refrigerant liquefied by the refrigerant supply unit is further provided, and the cooling nozzle discharges the refrigerant containing the liquid component atomized by the atomization means toward the substrate surface. You may comprise. According to this configuration, the liquid component of the refrigerant can be atomized and discharged from the cooling nozzle, and the liquid component can be easily vaporized. Therefore, it is possible to prevent the liquid component from being supplied to the substrate surface and to freeze the liquid film well.

  In addition, as an example of a configuration for moving the cooling nozzle relative to the substrate, the following configuration can be employed. That is, a rotation means for rotating the substrate is further provided, and the relative movement mechanism has a drive means for driving the cooling nozzle to move between the rotation center position of the substrate and the edge position of the substrate. Can do. According to such a configuration, it is possible to generate a frozen film on the entire surface of the substrate while limiting the coolant supply region to a minute region on the substrate surface.

  Further, when a film removing unit for removing the frozen film from the substrate surface is further provided, the contaminant can be effectively removed from the substrate surface even when the contaminant is attached to the substrate surface. That is, by freezing the liquid film formed on the substrate surface, the liquid film expands in volume, weakening the adhesive force between the substrate surface and the contaminant adhering to the substrate surface, and further, the contaminant is transferred to the substrate. Detach from the surface. Therefore, the contaminant can be easily removed from the substrate surface by removing the frozen film from the substrate surface. In particular, according to the present invention, the discharge refrigerant temperature can be lowered, so that the contaminant removal rate can be improved as shown in the experimental results described later.

  According to the present invention, the coolant having a temperature lower than the freezing point of the liquid constituting the liquid film formed on the substrate surface is locally discharged from the cooling nozzle toward the substrate surface, and the cooling nozzle is moved along the substrate surface. The frozen film is generated on the substrate surface by moving the substrate relative to the substrate. For this reason, it is possible to suppress the temperature drop of the substrate peripheral member to the minimum necessary and to suppress the deterioration of the durability of the substrate peripheral member. In addition, a gas essentially containing oxygen or argon is used as a refrigerant, and the gas is cooled and sent to the cooling nozzle in a state where at least a part of oxygen or argon is liquefied, and is discharged from the cooling nozzle. Thereby, the discharged refrigerant temperature can be lowered, and the load on the cooling device (refrigerant supply unit) required for cooling the refrigerant can be reduced.

<Particle removal effect of freezing process using gas containing oxygen essential>
The inventor of the present application has verified through experiments the effect of removing particles when the freezing treatment is performed using a gas that essentially contains oxygen as a refrigerant. Specifically, the relationship between the volume percentage of oxygen (hereinafter referred to as “oxygen concentration”) in the mixed fluid in which oxygen is mixed with nitrogen gas and the particle removal rate was examined. Here, the particle removal rates were compared and evaluated when the oxygen concentration was 0% (nitrogen gas 100%), 5% (nitrogen gas 95%), 21% (nitrogen gas 79%), and 100% (nitrogen-free). In the evaluation, a bare wafer (no pattern is formed) Si wafer (wafer diameter: 300 mm) is used as a typical example of the substrate. In addition, evaluation is performed for the case where the wafer surface is contaminated with Si scrap as particles.

  FIG. 1 is a diagram showing the relationship between the oxygen concentration and the particle removal rate. In this evaluation, in order to confirm the reproducibility of the experimental results, the particle removal rate is obtained using two samples for each oxygen concentration. The procedure for deriving the particle removal rate is as follows.

  First, a wafer is forcibly contaminated using a single-wafer-type substrate processing apparatus (Dainippon Screen Mfg. Co., Ltd., spin processor SS-3000. Specifically, particles (Si The dispersion liquid in which the waste is dispersed is supplied to the wafer, where the amount of the dispersion liquid, the number of rotations of the wafer, and the processing time are appropriately adjusted so that the number of particles adhering to the wafer surface is about 10,000. Thereafter, the number (initial value) of particles (particle size: 0.1 μm or more) adhering to the wafer surface is measured using a wafer inspection apparatus SP1 manufactured by KLA-Tencor. The evaluation is performed on the remaining area by removing (edge cutting) the peripheral area from the outer periphery of the wafer to 3 mm.

  Next, DIW (deionized water) is supplied from the surface nozzle onto the wafer surface to puddle liquid, and DIW is shaken off at a predetermined rotation speed (100 rpm) to form a liquid film (water film) on the wafer surface. To do. The thickness of the liquid film was about 100 μm as a result of obtaining from the wafer weight before and after forming the liquid film.

  Subsequently, the liquid film formed on the wafer surface is frozen by scanning the cooling nozzle along the wafer surface while discharging the coolant from the cooling nozzle toward the wafer surface. Thereby, a frozen film is generated on the entire surface of the wafer. Here, after discharging the coolant from the cooling nozzle, the cooling nozzle is moved from the standby position away from the wafer onto the wafer and moved along the wafer surface (moved from the wafer center position toward the edge position) The cooling nozzle is returned to the standby position. The freezing conditions of the liquid film are as follows. That is, the refrigerant discharge flow rate was 60 L / min, the distance between the cooling nozzle and the wafer (hereinafter referred to as “gap”) was 6.5 mm, the wafer rotation speed was 4 rpm, and the freezing time was 80 sec. In addition, when the refrigerant | coolant temperature in a standby position was measured as mentioned later, it was -115-110 degreeC.

  When the liquid film freezing process is completed, the wafer surface is rinsed. Specifically, DIW is supplied to the wafer as a rinsing liquid (flow rate: 1.8 L / min) while rotating the wafer (wafer rotation speed: 500 rpm), and the wafer is rinsed for 30 seconds. Subsequently, the wafer is rotated at high speed to dry (spin dry) the wafer.

  Thus, the number of particles adhering to the wafer surface that has undergone a series of cleaning processes is measured. Then, the particle removal rate is obtained by comparing the number of particles after the cleaning process with the previously measured number of particles before the cleaning process (initial value).

  In the liquid film freezing process of the evaluation procedure described above, the oxygen concentration of the refrigerant is varied for each wafer, that is, the oxygen concentration is 0% (nitrogen gas 100%) for each wafer with respect to a plurality of wafers. The evaluation results shown in FIG. 1 can be obtained by freezing the liquid film using% (nitrogen gas 95%), 21% (nitrogen gas 79%), and 100% (nitrogen-free) gas. In addition, the refrigerant | coolant in oxygen concentration 21% is substituted with air.

  As can be seen from FIG. 1, the particle removal rate is markedly higher when gases having an oxygen concentration of 5%, 21%, and 100% are used as the refrigerant than when the oxygen concentration is 0% as the refrigerant. In addition, it can be seen that the improvement is almost uniform. That is, it has been clarified from experimental results that the particle removal rate can be remarkably improved by adding oxygen to nitrogen gas or using oxygen instead of nitrogen gas.

  Next, the inventor of the present application paid attention to the refrigerant temperature (discharged refrigerant temperature) in the process of investigating the cause of the improvement in the particle removal rate. Therefore, the effect of oxygen addition to nitrogen gas on the refrigerant temperature was verified by experiments. Specifically, the refrigerant temperature was compared and evaluated when (1) 100% nitrogen gas was used as the refrigerant and (2) a mixed fluid in which oxygen was mixed with nitrogen gas.

  FIG. 2 is a graph showing the refrigerant temperature when oxygen is not added and when oxygen is added. The horizontal axis of FIG. 2 shows the elapsed time when the cooling nozzle is scanned while discharging the refrigerant from the cooling nozzle. Moreover, the vertical axis | shaft of FIG. 2 has shown refrigerant | coolant temperature (discharge refrigerant | coolant temperature). The refrigerant temperature is measured by arranging a thermocouple at the center position of the opening surface of the nozzle outlet. For the thermocouple, an alumel-chromel (K) wire (Ni alloy and NiCr alloy joined) is used. Moreover, the temperature data measured with the thermocouple is output using the temperature recorder NR-1000 by Keyence Corporation. The refrigerant is cooled to a predetermined temperature by exchanging heat with liquid nitrogen and discharged from the cooling nozzle.

  FIG. 3 is a view showing a configuration of an apparatus for supplying the coolant to the wafer. A cooling tube 102 (SUS tube) immersed in liquid nitrogen is spirally arranged in a storage tank 101 for storing liquid nitrogen. One end side of the cooling pipe 102 is connected to a refrigerant supply source (not shown), and the other end of the cooling pipe 102 communicates with the cooling nozzle 104 via an introduction pipe 103 having a double piping structure. . For this reason, when the refrigerant is supplied from one end side of the cooling pipe 102, the refrigerant is cooled to a predetermined temperature through heat exchange between the refrigerant and liquid nitrogen through the cooling pipe 102, and the cooling nozzle is passed through the introduction pipe 103. It is sent to 104. As a result, the cooled refrigerant is discharged from the cooling nozzle 104. The cooling nozzle 104 is fixed to the distal end of the scan arm 105, while the base end portion of the scan arm 105 is connected to the rotation shaft 106. Therefore, the scan arm 105 can be swung around the rotation shaft 106 by driving the rotation shaft 106 by a rotation motor (not shown).

  As can be seen from FIG. 2, when 100% nitrogen gas is used as the refrigerant (when oxygen is not added), while the cooling nozzle 104 is moving on the wafer and away from the wafer. No significant change is seen in the discharged refrigerant temperature. On the other hand, when a mixed fluid in which oxygen was mixed with nitrogen gas as a refrigerant (when oxygen was added), the temperature was around −110 ° C. while the cooling nozzle 104 moved away from the wafer. It can be seen that the temperature of the discharged refrigerant rapidly decreases to −150 ° C. or less at the same time as it moves onto the wafer, and this temperature (temperature in a lowered state) is maintained until it is retracted from the wafer. That is, a phenomenon (hereinafter referred to as “temperature decrease phenomenon”) in which the discharge refrigerant temperature rapidly decreases only while the cooling nozzle 104 is positioned on the wafer was confirmed.

  Here, the discharge refrigerant temperature when the oxygen concentration was changed (the oxygen concentration was 5%, 21%, 100%) was also evaluated. However, regardless of the oxygen concentration, a temperature decrease phenomenon occurs due to the addition of oxygen to the nitrogen gas. It was confirmed. Specifically, in the case of 100% nitrogen gas (oxygen concentration 0%), the occurrence of a temperature decrease phenomenon was not observed while the cooling nozzle 104 moved on the wafer, whereas the oxygen concentration was 5% ( In the case of nitrogen gas 95%), 21% ((nitrogen gas 79%), and 100% (not containing nitrogen), it was confirmed that the temperature drop phenomenon occurred while the cooling nozzle 104 moved on the wafer.

  In addition, when a gas containing oxygen was used as the refrigerant, it was confirmed that the refrigerant was conveyed to the cooling nozzle 104 in a liquefied state. This is because the boiling point of oxygen (−183 ° C.) is higher than the boiling point of nitrogen (−195.8 ° C.), and the liquefaction rate of oxygen with respect to nitrogen increases due to heat exchange between the refrigerant and liquid nitrogen. This can be explained. Therefore, it is considered that at least a part of oxygen is liquefied by cooling (heat exchange) and carried to the cooling nozzle 104 for the occurrence of the temperature decrease phenomenon.

  Further, in order to confirm whether or not the temperature decrease phenomenon depends on the distance between the cooling nozzle 104 and the wafer (hereinafter referred to as “gap”), the gap is changed using a mixed fluid as a refrigerant (the gap is 2. The data of the refrigerant temperature when the gap was 5 mm and the gap was 10 mm were obtained. (FIG. 4).

  FIG. 4 is a graph showing the refrigerant temperature when the distance between the cooling nozzle and the wafer is changed. As is clear from FIG. 4, it has been clarified that the temperature decrease phenomenon occurs in the same way when the gap is 2.5 mm and when the gap is 10 mm, and it does not depend greatly on the gap.

  On the other hand, this inventor verified by experiment about the relationship between refrigerant | coolant temperature and a particle removal rate (FIG. 5). FIG. 5 shows the particle removal rate when a liquid film is frozen at a different coolant temperature for each wafer for a plurality of wafers. As apparent from FIG. 5, it was found that the particle removal rate was improved as the refrigerant temperature was lowered.

  Therefore, considering the above experimental results in total, the temperature of the refrigerant (discharged refrigerant temperature) is lowered due to the temperature lowering phenomenon that occurs when oxygen-containing gas is used as the refrigerant, thereby improving the particle removal rate. It became clear. In addition, it is considered that the occurrence of the temperature decrease phenomenon is due to the fact that at least a part of oxygen is liquefied by cooling and carried to the cooling nozzle because the boiling point of oxygen is higher than that of nitrogen. The

  From the above viewpoint, a gas that essentially contains argon (boiling point: −185.9 ° C.) having a boiling point substantially equal to oxygen can be used as the refrigerant. Even when such a gas is used, it is possible to generate a temperature drop phenomenon by exhibiting a behavior similar to that of oxygen.

  Therefore, in view of the above knowledge, the liquid film formed on the substrate surface is frozen by moving the cooling nozzle relative to the substrate while discharging the gas containing oxygen or argon as a refrigerant from the cooling nozzle. Then, a frozen film is generated on the substrate surface.

<Substrate processing equipment>
FIG. 6 is a view showing an embodiment of a substrate processing apparatus according to the present invention. FIG. 7 is a block diagram showing a control configuration of the substrate processing apparatus of FIG. This apparatus is a single-wafer type substrate processing apparatus used for a cleaning process for removing contaminants such as particles adhering to the surface Wf of a substrate W such as a semiconductor wafer. More specifically, after forming a liquid film on the substrate surface Wf on which the fine pattern is formed, freezing the liquid film and then removing the frozen liquid film (frozen film) from the substrate surface Wf, This is an apparatus for performing a series of cleaning processes (liquid film formation + liquid film freezing + film removal) on the substrate W.

  The substrate processing apparatus includes a processing chamber 1 having a processing space for cleaning the substrate W therein, and the substrate W is placed in a substantially horizontal posture with the substrate surface Wf facing upward in the processing chamber 1. Spin chuck 2 that is held and rotated (corresponding to “substrate holding means” of the present invention), and a cooling nozzle that discharges a coolant for freezing the liquid film toward the surface Wf of the substrate W held on the spin chuck 2 3 and a blocking member 5 disposed to face the surface Wf of the substrate W held by the spin chuck 2.

  The spin chuck 2 has a rotation support shaft 21 connected to a rotation shaft of a chuck rotation mechanism 22 including a motor, and can rotate around a rotation center A0 by driving the chuck rotation mechanism 22. A disc-shaped spin base 23 is integrally connected to the upper end portion of the rotation spindle 21 by a fastening component such as a screw. Therefore, the spin base 23 rotates around the rotation center A0 by driving the chuck rotation mechanism 22 in accordance with an operation command from the control unit 4 (FIG. 7) that controls the entire apparatus. Thus, in this embodiment, the chuck rotating mechanism 22 functions as the “rotating unit” of the present invention.

  Near the periphery of the spin base 23, a plurality of chuck pins 24 for holding the periphery of the substrate W are provided upright. Three or more chuck pins 24 may be provided to securely hold the circular substrate W, and are arranged at equiangular intervals along the peripheral edge of the spin base 23. Each of the chuck pins 24 includes a substrate support portion that supports the peripheral portion of the substrate W from below, and a substrate holding portion that holds the substrate W by pressing the outer peripheral end surface of the substrate W supported by the substrate support portion. Yes. Each chuck pin 24 is configured to be switchable between a pressing state in which the substrate holding portion presses the outer peripheral end surface of the substrate W and a released state in which the substrate holding portion is separated from the outer peripheral end surface of the substrate W.

  When the substrate W is delivered to the spin base 23, the plurality of chuck pins 24 are released, and when the substrate W is cleaned, the plurality of chuck pins 24 are pressed. State. By setting the pressed state, the plurality of chuck pins 24 can grip the peripheral edge of the substrate W and hold the substrate W in a substantially horizontal posture at a predetermined interval from the spin base 23. As a result, the substrate W is held with the front surface (pattern forming surface) Wf facing upward and the back surface Wb facing downward.

  A rotation motor 31 that functions as the “driving means” of the present invention is provided outside the spin chuck 2. A rotation shaft 33 is connected to the rotation motor 31. A scan arm 35 is connected to the rotation shaft 33 so as to extend in the horizontal direction, and the cooling nozzle 3 is attached to the tip of the scan arm 35. The scan motor 35 can be swung around the rotation shaft 33 by driving the rotation motor 31 in accordance with an operation command from the control unit 4.

  FIG. 8 is a view showing the operation of the cooling nozzle provided in the substrate processing apparatus of FIG. Here, FIG. 4A is a side view and FIG. 4B is a plan view. When the rotation motor 31 is driven and the scan arm 35 is swung, the cooling nozzle 3 faces the substrate surface Wf and moves from the movement locus T in FIG. It moves along the trajectory T toward the edge position Pe. Here, the rotation center position Pc of the substrate W is set above the substrate surface Wf and on the rotation center A0 of the substrate W. Further, the cooling nozzle 3 is movable to a standby position Ps retracted to the side of the substrate W. Thus, in this embodiment, the rotation motor 31 functions as a “relative movement mechanism” that moves the cooling nozzle 3 relative to the substrate W along the substrate surface Wf.

  The cooling nozzle 3 is connected to the refrigerant supply unit 15, and the refrigerant is pumped from the refrigerant supply unit 15 to the cooling nozzle 3 in accordance with an operation command from the control unit 4. As a result, the coolant is locally discharged from the cooling nozzle 3 toward the substrate surface Wf. Therefore, in a state where the coolant is discharged from the cooling nozzle 3, the control unit 4 moves the cooling nozzle 3 along the movement trajectory T while rotating the substrate W, thereby supplying the coolant to the entire surface of the substrate surface Wf. be able to. As a result, when the liquid film 11 is formed on the substrate surface Wf as described later, the entire liquid film 11 can be frozen and the frozen film 13 can be generated on the entire surface of the substrate surface Wf. In this embodiment, since the liquid film 11 formed on the substrate surface Wf is composed of DIW (deionized water), the temperature of the refrigerant discharged toward the substrate surface Wf (discharged refrigerant temperature) is the freezing point of DIW ( The temperature is lower than the freezing point), preferably from −100 ° C. or less, more preferably −150 ° C. or less from the viewpoint of improving the particle removal rate.

  The refrigerant supply unit 15 pressure-feeds the refrigerant cooled to a predetermined temperature by the same configuration as that shown in FIG. 3 to the cooling nozzle 3. That is, the refrigerant supply unit 15 includes a storage tank that stores liquid nitrogen and a cooling pipe that is immersed in the liquid nitrogen stored in the storage tank, and cools the refrigerant sent from the refrigerant supply source to the cooling pipe. Pump toward 3 Here, heat exchange is performed between the refrigerant and liquid nitrogen through the cooling pipe, and the refrigerant is cooled to a predetermined temperature. In this embodiment, a mixed fluid in which oxygen is mixed with nitrogen gas is used as the refrigerant, and the mixed fluid is supplied from the refrigerant supply unit 15 to the cooling nozzle 3 in a state where at least a part of oxygen is liquefied by cooling (heat exchange). Is sent to.

  9 is a perspective view showing a configuration of a cooling nozzle provided in the substrate processing apparatus of FIG. A mesh member 37 is fitted into the cooling nozzle 3 in a flow path through which the mixed fluid flows. For this reason, the mixed fluid sent to the cooling nozzle 3 from the refrigerant supply unit 15 is discharged from the nozzle discharge port 3 a via the mesh member 37. For this reason, the liquid mixture (liquefied oxygen) can be atomized by the mixed fluid passing through the mesh member 37. As a result, the liquid component is discharged from the nozzle discharge port 3a in the atomized state, and the liquid component can be easily vaporized before reaching the liquid film 11 on the substrate surface Wf. Accordingly, it is possible to prevent the liquid component from being supplied to the substrate surface Wf. Thus, in this embodiment, the mesh member 37 functions as the “atomization means” of the present invention.

  Returning to FIG. 6, the description will be continued. The rotation support shaft 21 of the spin chuck 2 is a hollow shaft. A processing liquid supply pipe 25 for supplying DIW to the back surface Wb of the substrate W is inserted into the rotary spindle 21. The processing liquid supply tube 25 extends to a position close to the lower surface (back surface Wb) of the substrate W held by the spin chuck 2, and the processing liquid that discharges DIW toward the center of the lower surface of the substrate W at the tip thereof. A nozzle 27 is provided. The processing liquid supply pipe 25 is connected to the DIW supply unit 16 (FIG. 7), and DIW is supplied from the DIW supply unit 16.

  A gap between the inner wall surface of the rotation spindle 21 and the outer wall surface of the processing liquid supply pipe 25 forms a cylindrical gas supply path 29. The gas supply path 29 is connected to the dry gas supply unit 17 (FIG. 7), and nitrogen gas can be supplied as a dry gas to a space formed between the spin base 23 and the substrate back surface Wb. In this embodiment, nitrogen gas is supplied from the dry gas supply unit 17 as a dry gas. However, air or other inert gas may be discharged instead of the nitrogen gas.

  Further, a disc-shaped blocking member 5 having an opening at the center is provided above the spin chuck 2. The blocking member 5 has a lower surface (bottom surface) that faces the substrate surface Wf and is substantially parallel to the substrate surface Wf. The planar size of the blocking member 5 is equal to or larger than the diameter of the substrate W. The blocking member 5 is mounted substantially horizontally on the lower end portion of the support shaft 51 having a substantially cylindrical shape, and the support shaft 51 is held rotatably about a vertical axis passing through the center of the substrate W by an arm 52 extending in the horizontal direction. . The arm 52 is connected to a blocking member rotating mechanism 53 and a blocking member lifting mechanism 54.

  The blocking member rotating mechanism 53 rotates the support shaft 51 around the vertical axis passing through the center of the substrate W in accordance with an operation command from the control unit 4. The blocking member rotating mechanism 53 is configured to rotate the blocking member 5 in the same rotational direction as the substrate W and at substantially the same rotational speed in accordance with the rotation of the substrate W held by the spin chuck 2. Further, the blocking member elevating mechanism 54 can cause the blocking member 5 to be close to and opposed to the spin base 23 in accordance with an operation command from the control unit 4, or to be separated. Specifically, the control unit 4 operates the blocking member elevating mechanism 54 so that when the substrate W is loaded into or unloaded from the apparatus, the control unit 4 is moved to a separation position (position shown in FIG. 6) above the spin chuck 2. The blocking member 5 is raised. On the other hand, when a predetermined process is performed on the substrate W, the blocking member 5 is lowered to a facing position set very close to the surface Wf of the substrate W held by the spin chuck 2.

  The support shaft 51 is finished to be hollow, and a gas supply path 55 communicating with the opening of the blocking member 5 is inserted into the support shaft 51. The gas supply path 55 is connected to the dry gas supply unit 17, and nitrogen gas is supplied from the dry gas supply unit 17. In this embodiment, nitrogen gas is supplied from the gas supply path 55 to the space formed between the blocking member 5 and the substrate surface Wf during the drying process after the cleaning process for the substrate W. A liquid supply pipe 56 communicating with the opening of the blocking member 5 is inserted into the gas supply path 55, and a nozzle 57 is coupled to the lower end of the liquid supply pipe 56. The liquid supply pipe 56 is connected to the DIW supply unit 16, and DIW can be discharged from the nozzle 57 toward the substrate surface Wf when DIW is supplied from the DIW supply unit 16.

  Next, the cleaning processing operation in the substrate processing apparatus configured as described above will be described with reference to FIG. FIG. 10 is a flowchart showing the operation of the substrate processing apparatus of FIG. In this apparatus, when an unprocessed substrate W is carried into the processing chamber 1, the control unit 4 controls each part of the apparatus to perform a series of cleaning processes (liquid film formation + liquid film freezing) on the surface Wf of the substrate W. + Film removal). Here, a fine pattern may be formed on the substrate surface Wf. That is, the substrate surface Wf is a pattern formation surface. Therefore, in this embodiment, the substrate W is carried into the processing chamber 1 with the substrate surface Wf facing upward, and is held by the spin chuck 2 (step S1). Note that the blocking member 5 is located at a separated position to prevent interference with the substrate W.

  When the unprocessed substrate W is held on the spin chuck 2, the blocking member 5 is lowered to the facing position and is disposed close to the substrate surface Wf. As a result, the substrate surface Wf is covered in a state of being close to the substrate facing surface of the blocking member 5 and is blocked from the ambient atmosphere of the substrate W. Then, the control unit 4 drives the chuck rotating mechanism 22 to rotate the spin chuck 2 and supplies DIW from the nozzle 57 to the substrate surface Wf. Then, by rotating the substrate W at a predetermined rotation speed, the DIW supplied to the substrate surface is uniformly spread outward in the radial direction of the substrate W, and part of the DIW is shaken out of the substrate. Thereby, the thickness of the liquid film is uniformly controlled over the entire surface of the substrate surface Wf, and a liquid film (water film) 11 having a predetermined thickness is formed on the entire surface of the substrate Wf (step S2).

  When the liquid film forming process is completed, the freezing process is performed on the substrate W held on the spin chuck 2 with the liquid film 11 formed on the substrate surface Wf. That is, the control unit 4 disposes the blocking member 5 at the separation position and moves the cooling nozzle 3 from the standby position Ps to the refrigerant supply start position, that is, the rotation center position Pc of the substrate W while discharging the refrigerant from the cooling nozzle 3. . At this time, as shown in FIG. 2, when the cooling nozzle 3 faces the substrate surface Wf, the refrigerant temperature (discharged refrigerant temperature) rapidly decreases. Then, the cooling nozzle 3 is gradually moved toward the edge position Pe of the substrate W while discharging the coolant toward the surface Wf of the substrate W being rotationally driven. As a result, the liquid film 11 formed on the substrate surface Wf is locally frozen, and a region (frozen region) where the liquid film 11 is frozen in the surface region of the substrate surface Wf is a substrate surface Wf as shown in FIG. It is spread from the center to the periphery. As a result, the entire liquid film 11 formed on the substrate surface Wf is frozen, and a frozen film (ice film) 13 is formed on the entire surface of the substrate surface Wf (step S3). The temperature drop of the refrigerant is maintained while the cooling nozzle 3 is scanning on the substrate surface Wf.

  When the liquid film freezing process is performed in this manner, the volume of the liquid film entering between the substrate surface Wf and the contaminants adhering to the substrate surface Wf increases, and the contaminants are separated from the substrate surface Wf by a minute distance. Get away from. As a result, the adhesion force between the substrate surface Wf and the contaminant is reduced, and further, the contaminant is detached from the substrate surface Wf.

  When the liquid film freezing process is completed, the control unit 4 moves the cooling nozzle 3 to the standby position Ps. Subsequently, a film removal process is performed on the substrate W. That is, the blocking member 5 is disposed at the opposing position, and the blocking member 5 is rotated together with the spin chuck 2. Further, nitrogen gas is supplied to the space between the substrate W and the spin base 23 and between the substrate W and the blocking member 5. Then, after the atmosphere around the substrate W is changed to an inert gas atmosphere, DIW is supplied from the nozzle 57 and the processing liquid nozzle 27 to the front and back surfaces Wf and Wb of the substrate W that is rotationally driven. As a result, the supply of DIW to the front and back surfaces Wf and Wb of the substrate W being rotated is started, and the film removal process by DIW is executed. As a result, the frozen film 13 containing the contaminant is melted and removed from the substrate surface Wf (step S4). That is, since the contaminant is in a state where the adhesion to the substrate surface Wf is reduced or detached from the substrate surface Wf, the contaminant is easily removed from the substrate surface Wf by removing the frozen film 13 from the substrate surface Wf. Is done. Thus, in this embodiment, the nozzle 57 functions as the “film removing means” of the present invention.

  Thus, when the film removal process is completed and the cleaning process of the substrate W (liquid film formation + liquid film freezing + film removal) is completed (YES in step S5), the drying process of the substrate W is subsequently executed. On the other hand, depending on the surface state of the substrate surface Wf to be processed or the size and type of the contaminant to be removed, the contaminant may not be sufficiently removed from the substrate surface Wf by a single cleaning process. . In this case (NO in step S5), the liquid film freezing process and the film removing process are repeatedly executed after the film removing process is completed. That is, DIW remains on the substrate surface Wf after the film removal process. Therefore, even if the liquid film 11 is not newly formed on the substrate surface Wf, the substrate surface Wf is covered with the remaining liquid film 11. Therefore, when the liquid film freezing process is executed after the film removal process, the frozen film 13 composed of DIW is formed. Then, by removing the frozen film 13 in the film removal process, contaminants attached to the substrate surface Wf are removed from the substrate surface Wf together with the frozen film 13. Thus, the contaminant removal is removed from the substrate surface Wf by repeatedly executing the film removal process and the liquid film freezing process a predetermined number of times.

  When the cleaning of the substrate W is completed, the control unit 4 increases the rotation speeds of the motors of the chuck rotating mechanism 22 and the blocking member rotating mechanism 53 to rotate the substrate W and the blocking member 5 at high speed. Thereby, the drying process (spin drying) of the substrate W is executed (step S6). After the drying process of the substrate W, the rotation of the substrate W and the blocking member 5 is stopped and the supply of nitrogen gas to the substrate W is stopped. Thereafter, the processed substrate W is unloaded from the processing chamber 1 (step S7).

  As described above, according to this embodiment, the coolant having a temperature lower than the freezing point of the liquid constituting the liquid film 11 formed on the substrate surface Wf is locally discharged from the cooling nozzle 3 toward the substrate surface Wf. is doing. Then, while the substrate W is rotated, the cooling nozzle 3 is moved between the rotation center position Pc of the substrate W and the edge position Pe of the substrate W to generate the frozen film 13 on the substrate surface Wf. For this reason, the supply part of the coolant is limited to a minute region on the substrate surface Wf, and the temperature decrease of the peripheral members of the substrate such as the spin chuck 2 can be minimized. Accordingly, the frozen film 13 can be generated on the substrate surface Wf while suppressing the deterioration of the durability of the substrate peripheral member. As a result, even if the substrate peripheral member is formed of a resin material (resin material having chemical resistance) that is difficult to ensure cold resistance, deterioration of the material of the substrate peripheral member due to cold can be suppressed.

  In addition, a gas essentially containing oxygen or argon is used as a refrigerant, and the gas is cooled and sent to the cooling nozzle 3 in a state where at least a part of oxygen is liquefied and discharged from the cooling nozzle 3. Thereby, compared with the case where 100% nitrogen gas is simply used as a refrigerant | coolant, it is possible to reduce discharge refrigerant | coolant temperature. Therefore, the discharged refrigerant temperature is set to a temperature suitable for freezing the liquid film 11 without cooling the refrigerant by the cooling device (refrigerant supply unit) so that the discharged refrigerant temperature is lowered to a temperature suitable for freezing the liquid film 11. Can be cooled down to. Therefore, the load on the cooling device can be reduced as compared with the case where 100% nitrogen gas is used as the refrigerant. As a result, the amount of liquid nitrogen used for cooling the gas used for the refrigerant can be reduced.

  Moreover, according to this embodiment, compared with the case where 100% nitrogen gas is used as a refrigerant | coolant, it is possible to reduce discharge refrigerant | coolant temperature. For this reason, as shown in FIG. 5, the removal rate of contaminants, such as a particle, can be improved markedly.

  In addition, as is clear from the experimental results, the temperature decrease phenomenon as described above contributes that at least a part of oxygen is liquefied by cooling, but in this embodiment, oxygen was mixed with nitrogen gas. Since the mixed fluid is used, the following effects can be obtained. That is, when oxygen is used alone, the amount of refrigerant supplied to the substrate surface Wf in a liquefied state increases, and it becomes difficult to freeze the liquid film 11 well. On the other hand, if a mixed fluid in which oxygen is mixed with nitrogen gas is used as a refrigerant, the boiling point of nitrogen (-195.8 ° C.) is lower than the boiling point of oxygen (−183 ° C.). Only the liquid can be liquefied and fed into the cooling nozzle 3. Thereby, it can suppress that a liquid component (liquefied oxygen) is supplied to the substrate surface Wf, and can freeze the liquid film 11 favorably. Further, in this embodiment, the mesh member 37 is disposed in the cooling nozzle 3 to atomize the liquid component and discharge it from the nozzle discharge port 3a. For this reason, a liquid component can be vaporized easily and it can prevent effectively that a liquid component is supplied to the board | substrate surface Wf.

<Others>
The present invention is not limited to the above-described embodiment, and various modifications other than those described above can be made without departing from the spirit of the present invention. For example, in the above embodiment, a mixed fluid in which oxygen is mixed with nitrogen gas is used as the refrigerant. However, the present invention is not limited to this, and a mixed fluid in which argon is mixed with nitrogen gas may be used as the refrigerant. The boiling point of argon (−185.9 ° C.) is almost equal to the boiling point of oxygen (−183 ° C.), and even when a mixed fluid in which nitrogen gas is mixed with argon is used as a refrigerant, argon shows almost the same behavior as oxygen. Thus, it is possible to cause a temperature drop phenomenon. In addition, oxygen or argon may be used alone as the refrigerant as long as there is no hindrance to the execution of the liquid film freezing process.

  In the above embodiment, the mesh member 37 is used as the “atomization means” of the present invention. However, instead of the mesh member, a member having a large number of fine holes or a member formed of a porous material is used. It may be used.

  In the above embodiment, the refrigerant is supplied to the liquid film 11 formed on the substrate surface Wf to form the frozen film 13 (surface-side frozen film) on the substrate surface Wf, but not only the substrate surface Wf, A frozen film (back surface side frozen film) may also be formed on the substrate back surface Wb. Then, by removing the surface-side frozen film and the back-side frozen film from the substrate W by rinsing, the front and back surfaces Wf and Wb of the substrate W can be cleaned without inverting the substrate W or the like.

  In the above embodiment, the cooling nozzle 3 is moved with respect to the substrate W by moving the cooling nozzle 3 between the rotation center position Pc of the substrate W and the edge position Pe of the substrate W while rotating the substrate W. Although the relative movement is performed, the configuration for moving the cooling nozzle 3 relative to the substrate W is not limited thereto. For example, the freezing process may be executed while moving the substrate W in a predetermined direction with the cooling nozzle 3 fixedly arranged. Further, the freezing process may be executed while moving both the cooling nozzle 3 and the substrate W.

  In the above embodiment, the liquid film 11 is formed on the substrate W using DIW. However, in addition to DIW, carbonated water, hydrogen water, diluted ammonia water (for example, about 1 ppm), diluted hydrochloric acid, etc. The liquid film 11 may be formed using the rinse liquid. Further, the liquid film 11 may be formed using a chemical solution in addition to the rinse solution.

  In the above embodiment, the frozen film 13 is removed from the substrate W using DIW in the film removal process. In addition to DIW, carbonated water, hydrogen water, dilute concentration (for example, about 1 ppm) ammonia water, dilute A rinse solution such as hydrochloric acid having a concentration may be used. Further, before the rinsing process with the rinsing liquid is performed, the chemical liquid process (chemical cleaning) may be performed using a chemical liquid such as an SC1 solution (mixed aqueous solution of ammonia water and hydrogen peroxide solution) as the film removal process. By using such a chemical solution, contaminants can be effectively removed from the substrate W. Further, in the film removal process, a droplet such as particles may be physically removed (physical cleaning) by the kinetic energy of the droplet by supplying the droplet from the two-fluid nozzle to the substrate surface Wf.

  The present invention relates to a semiconductor wafer, a glass substrate for photomask, a glass substrate for liquid crystal display, a glass substrate for plasma display, a substrate for FED (Field Emission Display), a substrate for optical disk, a substrate for magnetic disk, a substrate for magneto-optical disk, etc. The present invention can be applied to a substrate processing apparatus and a substrate processing method for freezing a liquid film formed on the entire surface of a substrate including the substrate.

It is a figure which shows the relationship between oxygen concentration and a particle removal rate. It is a graph which shows the refrigerant | coolant temperature in the case of oxygen addition without oxygen addition. It is a figure which shows the apparatus structure for supplying a refrigerant | coolant to a wafer. It is a graph which shows the refrigerant | coolant temperature when changing the distance between a cooling nozzle and a wafer. It is a figure which shows the relationship between refrigerant | coolant temperature and a particle removal rate. It is a figure showing one embodiment of a substrate processing device concerning this invention. It is a block diagram which shows the control structure of the substrate processing apparatus of FIG. It is a figure which shows operation | movement of the cooling nozzle with which the substrate processing apparatus of FIG. 6 was equipped. It is a perspective view which shows the structure of the cooling nozzle with which the substrate processing apparatus of FIG. 6 was equipped. It is a flowchart which shows operation | movement of the substrate processing apparatus of FIG.

Explanation of symbols

2 ... Spin chuck (substrate holding means)
DESCRIPTION OF SYMBOLS 3 ... Cooling nozzle 11 ... Liquid film 13 ... Freezing film 15 ... Refrigerant supply part 22 ... Chuck rotation mechanism (rotation means)
31 ... Rotating motor (driving means, relative moving mechanism)
37. Mesh member (atomization means)
57 ... Nozzle (film removal means)
Pc ... Rotation center position Pe ... Edge edge position W ... Substrate Wf ... Substrate surface

Claims (6)

In a substrate processing apparatus suitable for a freezing process for freezing a liquid film formed on a substrate surface,
Substrate holding means for holding the substrate in a state in which a liquid film is formed on the substrate surface;
A cooling nozzle that locally discharges a coolant having a temperature lower than the freezing point of the liquid constituting the liquid film toward the surface of the substrate held by the substrate holding means;
A relative movement mechanism for moving the cooling nozzle relative to the substrate along the surface of the substrate while facing the surface of the substrate;
A refrigerant supply unit that uses a gas essentially containing oxygen or argon as the refrigerant, and that cools the gas and liquefies at least part of oxygen or argon, and sends the refrigerant to the cooling nozzle ;
Atomizing means for atomizing the liquid component of the refrigerant liquefied by the refrigerant supply unit ,
The cooling nozzle discharges the coolant containing the liquid component atomized by the atomizing means toward the substrate surface, and until the atomized liquid component reaches the liquid film on the substrate surface. Vaporize and supply the liquid film after further cooling the gas,
The relative movement mechanism generates a frozen film on the substrate surface by moving the cooling nozzle that discharges the gas relative to the substrate.   The substrate processing apparatus according to claim 1, wherein the refrigerant supply unit cools the gas by heat exchange between the gas and liquid nitrogen.   The substrate processing apparatus according to claim 1, wherein the refrigerant supply unit sends a mixed fluid in which oxygen gas or argon is mixed with nitrogen gas to the cooling nozzle as the refrigerant. A rotating means for rotating the substrate held by the substrate holding means;
The relative movement mechanism, the substrate processing apparatus according to any one of claims 1 to 3 having a drive means for moving between the end edge position of the rotation center position of the substrate by driving the cooling nozzle the substrate . The substrate processing apparatus according to any one of claims 1 to 4 further comprising a film removing means for removing the frozen film from the substrate surface. In a substrate processing method suitable for a freezing process for freezing a liquid film formed on a substrate surface,
A discharge step of locally discharging a coolant having a temperature lower than the freezing point of the liquid constituting the liquid film from the cooling nozzle toward the surface of the substrate while holding the substrate in a state where the liquid film is formed on the substrate surface; ,
In parallel with the discharging step, a relative movement step of generating a frozen film on the substrate surface by moving the cooling nozzle relative to the substrate along the substrate surface while facing the substrate surface;
Using a gas essentially containing oxygen or argon as the refrigerant, and sending the cooled gas to the cooling nozzle in a state where at least a part of oxygen or argon is liquefied ;
A atomization step of atomizing the liquid component of the refrigerant liquefied by the delivery step ,
In the discharge step, the coolant containing the liquid component atomized by the atomization step is discharged toward the substrate surface, and the atomized liquid component reaches the liquid film on the substrate surface. The substrate processing method is characterized in that the gas is further cooled and the gas is further cooled and then supplied to the liquid film .

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