JP2017063130A - Substrate liquid processing apparatus and substrate drying method of substrate liquid processing apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To dry the whole area of one surface of a substrate evenly over time.SOLUTION: A substrate liquid processing apparatus includes a base plate 31a provided with a substrate holding part 31, a rotating shaft 32 for rotating the base plate 31a, a process liquid supply pipe 43 provided in the center of rotation of the rotating shaft 32, and having a liquid discharge port for discharging the process liquid toward a substrate (wafer W) at the tip, and a circular head 42 arranging the liquid discharge port in the center, and capable of covering at least the gap between the rotating shaft 32 and the process liquid supply pipe 43. The base plate 31a has a ventilation path 90 penetrating one surface of the base plate 31a facing the substrate and the other surface, and generating airflow flowing from the other surface to one surface.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a technique for drying a substrate in a substrate liquid processing apparatus that performs a liquid processing by supplying a processing liquid to the substrate.

  In the manufacture of a semiconductor device, a substrate such as a semiconductor wafer is held horizontally and rotated around a vertical axis, and a cleaning liquid (for example, for cleaning) is applied to one surface of the substrate (for example, the back surface of the substrate that is a device non-forming surface). A chemical solution or a rinsing solution may be supplied to perform cleaning treatment on the one surface. After the cleaning of the one surface is completed, the substrate is spun off by rotating at high speed. At this time, an inert gas such as nitrogen gas is supplied to the one surface in order to prevent drying and generation of a water mark. For example, Patent Document 1 discloses a substrate liquid processing apparatus for executing the above-described series of processes.

Japanese Patent No. 5005571

  During the substrate drying process, one surface to be dried faces a planar member that performs functions such as holding and rotating the substrate. However, depending on the structure of the opposing planar member, there may be a region where the drying is delayed on the one surface compared to the other region. In order to eliminate such a delay in drying and dry the entire surface of the substrate, for example, the supply amount of the inert gas can be increased. However, there is a risk of increasing the cost.

  The present invention is for solving the above-described problems, and provides a technique capable of drying the entire surface of one surface of a substrate uniformly over time.

  The present invention is for solving the above-described problems, and a substrate liquid processing apparatus according to the present invention rotates a holding unit that holds a substrate in a horizontal position, a base plate provided with the holding unit, and the base plate. A rotating shaft, a processing liquid supply pipe provided in the rotating shaft and having a liquid discharging port at the tip for discharging a processing liquid toward the substrate, and the liquid discharging port are disposed, and at least the rotating shaft and the processing A head portion capable of covering a gap between the liquid supply pipe and the base plate penetrating one surface side and the other surface side of the base plate facing the substrate, and the other surface. A ventilation path for generating an airflow flowing from the side to the one surface side.

  According to the present invention, the entire surface of one side of the substrate can be uniformly dried over time.

It is a schematic plan view which shows the whole structure of the substrate liquid processing system which concerns on one Embodiment of this invention. It is sectional drawing which shows the structure of the processing unit of FIG. It is the top view which looked at the base plate from the upper part. It is a figure for demonstrating progress of drying of a wafer lower surface. It is the figure which represented typically the airflow between the lower surface of a wafer, and the upper surface of a baseplate.

  Hereinafter, specific configurations of the substrate liquid processing apparatus and the substrate liquid processing method according to the present invention will be described with reference to the drawings. In the following description, a case where the present invention is applied to a substrate processing system will be described as an embodiment of a substrate liquid processing apparatus according to the present invention.

  FIG. 1 is a diagram showing a schematic configuration of a substrate processing system according to the present embodiment. In the following, in order to clarify the positional relationship, the X axis, the Y axis, and the Z axis that are orthogonal to each other are defined, and the positive direction of the Z axis is the vertically upward direction.

  As shown in FIG. 1, the substrate processing system 1 includes a carry-in / out station 2 and a processing station 3. The carry-in / out station 2 and the processing station 3 are provided adjacent to each other.

  The carry-in / out station 2 includes a carrier placement unit 11 and a transport unit 12. A plurality of carriers C that accommodate a plurality of substrates, in this embodiment a semiconductor wafer (hereinafter referred to as a wafer W) in a horizontal state, are placed on the carrier placement unit 11.

  The transport unit 12 is provided adjacent to the carrier placement unit 11 and includes a substrate transport device 13 and a delivery unit 14 inside. The substrate transfer device 13 includes a wafer holding mechanism that holds the wafer W. Further, the substrate transfer device 13 can move in the horizontal direction and the vertical direction and can turn around the vertical axis, and transfers the wafer W between the carrier C and the delivery unit 14 using the wafer holding mechanism. Do.

  The processing station 3 is provided adjacent to the transfer unit 12. The processing station 3 includes a transport unit 15 and a plurality of processing units 16. The plurality of processing units 16 are provided side by side on the transport unit 15.

  The transport unit 15 includes a substrate transport device 17 inside. The substrate transfer device 17 includes a wafer holding mechanism that holds the wafer W. Further, the substrate transfer device 17 can move in the horizontal direction and the vertical direction and can turn around the vertical axis, and transfers the wafer W between the delivery unit 14 and the processing unit 16 using a wafer holding mechanism. I do.

  The processing unit 16 performs predetermined substrate processing on the wafer W transferred by the substrate transfer device 17.

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

  Such a program may be recorded on a computer-readable storage medium, and may be installed in the storage unit 19 of the control device 4 from the storage medium. Examples of the computer-readable storage medium include a hard disk (HD), a flexible disk (FD), a compact disk (CD), a magnetic optical disk (MO), and a memory card.

  In the substrate processing system 1 configured as described above, first, the substrate transfer device 13 of the loading / unloading station 2 takes out the wafer W from the carrier C placed on the carrier placement unit 11 and receives the taken-out wafer W. Place on the transfer section 14. The wafer W placed on the delivery unit 14 is taken out from the delivery unit 14 by the substrate transfer device 17 of the processing station 3 and carried into the processing unit 16.

  The wafer W carried into the processing unit 16 is processed by the processing unit 16, then unloaded from the processing unit 16 by the substrate transfer device 17, and placed on the delivery unit 14. Then, the processed wafer W placed on the delivery unit 14 is returned to the carrier C of the carrier placement unit 11 by the substrate transfer device 13.

  Next, a schematic configuration of the processing unit 16 will be described with reference to FIG.

  As shown in FIG. 2, the processing unit 16 is supplied to the chamber 20, a substrate holding and rotating mechanism 30 that holds and rotates the wafer W, a liquid discharge unit 40 that constitutes a processing liquid supply nozzle, and the wafer W. And a recovery cup 50 for recovering the subsequent processing liquid.

  The chamber 20 accommodates the substrate holding and rotating mechanism 30, the liquid discharge unit 40, and the recovery cup 50. An FFU (Fan Filter Unit) 21 is provided on the ceiling of the chamber 20. The FFU 21 forms a down flow in the chamber 20.

  The substrate holding and rotating mechanism 30 is configured as a mechanical chuck that holds the wafer W by a mechanical clamping mechanism. The substrate holding and rotating mechanism 30 includes a substrate holding unit 31, a rotation shaft 32, and a rotation motor (rotation drive unit) 33.

  The substrate holding part 31 has a disk-shaped base plate (plate-like body) 31a and a plurality of holding members 31b provided on the peripheral edge of the base plate 31a. The holding member 31b holds the periphery of the wafer W. In one embodiment, some of the plurality of holding members 31b are movable support members that move forward and backward with respect to the wafer W to switch between gripping and releasing the wafer W, and the remaining holding members 31b are non-moving holding members. It is. The rotating shaft 32 is hollow and extends vertically downward from the center of the base plate 31a. The rotation motor 33 drives the rotation shaft 32 to rotate, whereby the wafer W held in a horizontal posture by the substrate holding unit 31 rotates around the vertical axis.

  The liquid discharge part 40 is formed as an elongated shaft-like member that extends in the vertical direction as a whole. The liquid discharge part 40 has a hollow cylindrical shaft part 41 extending in the vertical direction and a head part 42. The shaft portion 41 is inserted into a cylindrical cavity 32 a inside the rotation shaft 32 of the substrate holding and rotating mechanism 30. The shaft portion 41 and the rotation shaft 32 are concentric. A space as a gas passage 80 having an annular cross section is formed between the outer peripheral surface of the shaft portion 41 and the inner peripheral surface of the rotating shaft 32.

  Inside the liquid ejection part 40 is a cylindrical cavity extending in the vertical direction. A processing liquid supply pipe 43 is provided inside the cavity. The upper end of the processing liquid supply pipe 43 is opened at the upper surface of the head portion 42 of the liquid discharge unit 40, and the liquid that discharges the processing liquid toward the central portion of the lower surface of the wafer W held by the substrate holding and rotating mechanism 30. Discharge port.

  A predetermined processing liquid for processing the lower surface of the wafer W is supplied from the processing liquid supply mechanism 72 to the processing liquid supply pipe 43. Although illustration and detailed description of the configuration of the processing liquid supply mechanism 72 are omitted, the processing liquid supply mechanism 72 includes, for example, a supply line connected to the processing liquid supply source, and an on-off valve and a flow rate control valve interposed in the supply line. The The processing liquid supply mechanism 72 may be configured to switch and supply a plurality of processing liquids, for example, a cleaning chemical (for example, DHF) and a rinsing liquid.

  The collection cup 50 is disposed so as to surround the substrate holding portion 31 of the substrate holding and rotating mechanism 30 and collects the processing liquid scattered from the rotating wafer W. The recovery cup 50 has a stationary lower cup body 51 and an upper cup body 52 that can be raised and lowered between a raised position (position shown in FIG. 2) and a lowered position. The upper cup body 52 is moved up and down by the lifting mechanism 53. When the upper cup body 52 is in the lowered position, the upper end of the upper cup body 52 is located at a position lower than the wafer W held by the substrate holding and rotating mechanism 30. For this reason, when the upper cup body 52 is in the lowered position, the wafer W is moved between the substrate holding mechanism (arm) of the substrate transport apparatus 17 shown in FIG. Can be delivered.

  A discharge port 54 is formed at the bottom of the lower cup body 51. The collected processing liquid and the atmosphere in the recovery cup 50 are discharged from the recovery cup 50 through the discharge port 54. A discharge pipe 55 is connected to the discharge port 54, and the discharge pipe 55 is connected to a factory exhaust system (not shown) in a reduced pressure atmosphere. The shielding plate 92 blocks the space between the lower surface of the base plate 31a and the rotary motor 33 so that the processing liquid used for the liquid processing does not adhere to the rotary motor 33 or the like.

  The downflow of clean air from the FFU 21 is drawn into the recovery cup 50 through the upper opening of the recovery cup 50 (upper cup body 52) and exhausted from the discharge port 54. For this reason, an air flow indicated by an arrow F is generated in the recovery cup 50.

  The processing unit 16 may further include at least one processing liquid supply nozzle 61 that supplies a processing liquid (cleaning liquid or rinsing liquid) to the upper surface of the wafer W held by the substrate holding and rotating mechanism 30. The processing unit 16 may further include a brush 62 for scrub cleaning the upper surface of the wafer W.

  There is an annular gap between the lower surface of the head 42 and the substrate holder 31 (particularly the base plate 31 a), and this gap serves as a gas discharge path 81. A gas discharge port 82 for discharging gas is defined by the peripheral edge of the head 42 and the base plate 31a. In order to prevent liquid (processing liquid discharged from the liquid discharge port and falling after reaching the lower surface of the wafer W) from entering the gas discharge path 81 and the gas passage 80 from the gas discharge port 82, the head 42 is prevented. Is a circle projecting outward in the radial direction and completely covers the gas passage 80 in plan view from above.

In the gas passage 80 between the shaft portion 41 and the rotary shaft 32 of the liquid discharge unit 40 described above, an inert gas as a purge gas, here nitrogen (N ₂ ) gas, is supplied from the drying gas supply mechanism 74. Supplied. Although illustration and detailed description of the configuration of the purge gas supply mechanism 74 are omitted, for example, from a supply line connected to the purge gas supply source, an on-off valve and a flow rate control valve provided in the supply line, etc. Composed. Nitrogen gas supplied to the gas passage 80 from the purge gas supply mechanism 74 flows into the gas discharge path 81 and is discharged from the gas discharge port 82.

  In the present embodiment, in order to promote drying of the lower surface of the wafer W after the liquid processing, one surface side of the base plate 31a facing the wafer W (the surface side of the base plate 31a) and the other surface side that is the opposite surface ( A ventilation passage 90 is provided to penetrate the back surface side of the base plate 31a. FIG. 3 is a plan view of the base plate 31a as viewed from above. As shown in the drawing, twelve air passages 90 are provided in the base plate 31a at intervals of 30 degrees in the radial direction with respect to the rotation center. The diameter of the air passage 90 is not limited as long as it functions for ventilation. The opening 91 is a portion joined to the rotating shaft 32, and has a slightly larger diameter than the head portion 42 in the present embodiment. Although details will be described later, the distance from the rotation center of the air passage 90 is determined based on the diameter of the head 42 that does not rotate during the drying process. In the present embodiment, the diameter of the head 42 is 60 mm, and the distance from the rotation center of the air passage 90 is 70 mm.

  Next, processing for the wafer W performed in the processing unit 16 will be briefly described.

  First, in a state where the upper cup body 52 is in the lowered position, the substrate holding mechanism (arm) of the substrate transfer device 17 enters the chamber 20 and transfers the wafer W to the holding unit 31 of the substrate holding and rotating mechanism 30. Thereafter, the substrate holding mechanism (arm) is withdrawn from the chamber 20, and the upper cup body 52 is raised to the raised position.

  Next, the substrate holding and rotating mechanism 30 rotates the wafer W. In this state, a predetermined liquid process is performed on the wafer W. An example of liquid treatment is described below. During a predetermined time, a cleaning chemical (for example, DHF) is supplied from the processing liquid supply nozzle 61 to the upper surface of the wafer W (the surface of the wafer W on which the device is formed), and at the same time, liquid discharge from the processing liquid supply pipe 43 is performed. A cleaning chemical (for example, DHF) is supplied from the outlet to the central portion (substantially the center) of the lower surface of the wafer (the back surface of the wafer W on which no device is formed), whereby the upper and lower surfaces of the wafer W are subjected to a chemical cleaning process. Is done.

  Next, while the wafer W is continuously rotated, a rinsing liquid (for example, pure water (DIW)) is supplied from the processing liquid supply nozzle 61 to the upper surface of the wafer W for a predetermined time, and at the same time, the processing liquid supply pipe 43 is supplied. A rinsing liquid (for example, pure water (DIW)) is supplied from the liquid discharge port to the center of the lower surface of the wafer W, and the upper surface and the lower surface of the wafer W are rinsed. As a result, the chemical solution remaining on the upper and lower surfaces of the wafer W and the reaction product generated by the chemical cleaning process are washed away by the rinse liquid. During the above liquid processing, nitrogen gas is supplied from the gas discharge port 82 in order to prevent the processing liquid from entering the gas discharge path 81.

  When the liquid processing is finished, the supply of liquid to the upper and lower surfaces of the wafer W is stopped, and the wafer W is continuously rotated (preferably, the rotation speed of the wafer is increased), and the upper and lower surfaces of the wafer W are removed. dry.

  Here, the experiment and consideration which the inventor performed regarding a drying process are demonstrated below.

  First, a rinsing process is performed on the lower surface of the wafer W using a processing unit having the same configuration as that shown in FIG. 2 except that the base plate 31a has no air passage 90, and then nitrogen gas is supplied. An experiment was conducted in which the drying treatment was performed without any problems. The experiment was performed by setting the rotation speed of the wafer to 2000 rpm and maintaining the rotation speed for a predetermined time during the drying process.

  When the wafer W was rotated for 49 seconds under the above conditions, the wafer W was completely dried. However, the following drying delay occurred in the time shorter than that. That is, when the wafer W was rotated for about 30 seconds and stopped, a circular dry residue 100 having a diameter of about 130 to 150 mm was confirmed on the lower surface of the wafer W (see FIG. 4A). When the wafer W was rotated for about 40 seconds and stopped, a ring-shaped dry residue 100 having a diameter of about 60 to 80 mm was confirmed on the lower surface of the wafer W (see FIG. 4B). When the wafer W was rotated for about 47 seconds and stopped, a ring-shaped dry residue 100 with a part missing was confirmed (see FIG. 4C). In the experiments at other rotational speeds, the position where the ring-shaped dry residue 100 was generated was slightly changed and the time until complete drying was different, but the same tendency was confirmed. From this, it was found that the most difficult region to dry is not the central portion of the wafer W but a ring-shaped region separated from the central portion of the wafer.

  From the above experimental results, promoting the drying of the ring-shaped region (approximately 20% to 30% from the center with respect to the radius of the wafer W) leads to a reduction in the drying time of the entire lower surface of the wafer W. I understood.

  FIG. 5A is a diagram schematically showing an air flow between the lower surface of the wafer W and the upper surface of the base plate 31a when the base plate 31a having no air passage is rotated to dry the wafer W. FIG. In the figure, in a region 501 (region of about 30% to 100% from the center with respect to the radius of the wafer W) outside the head 42 that does not rotate during the drying process, the wafer W enters from the outside. Then, an airflow 501a returning upward and an airflow 501b returning downward are generated. Accordingly, in the region 501, the evaporation of the liquid attached to the wafer W or the like is promoted by the air current 501a and the air current 501b, and the lower surface region of the wafer W corresponding to the region 501 finishes drying earlier than the other regions.

  Further, in a region 502 inside the head portion 42 (a region of about 0% to 20% from the center with respect to the radius of the wafer W), a pressure drop occurs due to the rotation of the wafer W, and it adheres to the wafer W or the like. The liquid is easily evaporated. Accordingly, the evaporation of the liquid is promoted, and the drying is completed earlier in the lower surface region of the wafer W corresponding to the region 501 than in the region 503 described later, although it is slower than the region 501.

  During the drying process, an area 503 near the boundary between the non-rotating head 42 and the upper surface of the rotating base plate 31a (an area of about 20% to 30% from the center with respect to the radius of the wafer W) looks like an area 501. Air flow is not generated and gas stagnation occurs. Further, no pressure drop occurs as in the region 502. For this reason, it is difficult to dry as compared with other regions, and when the drying of the other regions is completed, the ring-shaped drying residue 100 as described above exists in the lower surface region of the wafer W corresponding to the region 503.

  In the present embodiment, the airflow in the region 503 is eliminated by ventilation through the ventilation path 90. FIG. 5B is a diagram schematically showing an air flow between the lower surface of the wafer W and the upper surface of the base plate 31a when the base plate 31a having the air passage 90 is rotated to dry the wafer W. As shown in the figure, an air flow 503a that flows from the lower surface to the upper surface of the base plate 31a and travels toward the region 503 is generated. Then, the stagnant gas in the region 503 is replaced with the gas in the base plate 31a. Therefore, the delay in drying in the region 503 can be suppressed, and the drying is completed in the same time as compared to other regions, so that the entire surface of the wafer W can be uniformly dried in time. Further, compared to a method of drying the back surface of the wafer W using a drying gas, the cost can be reduced and the control of the apparatus can be simplified.

  Thus, in the above embodiment, the head 42 is positioned above the upper surface of the base plate 31a, and the distance between the upper surface of the head 42 and the lower surface of the wafer W is such that the upper surface of the base plate 31a and the lower surface of the wafer W are separated. It is narrower than the interval. The air passage 90 is outside the outer peripheral edge of the head portion 42, and has a region 502 with a narrow gap between the rotating wafer W and the lower surface of the wafer W formed between the rotating head portion 42 and the non-rotating head portion 42. It is formed in a region 503 between the base plate 31a that rotates together with the wafer W and a region 501 that is wide with the lower surface of the wafer W. The present invention is not limited to the above embodiment, and can be modified as described below, for example.

(Modification)
In the above-described embodiment, the processing liquid supplied to the back surface of the wafer W during the liquid processing falls from the wafer W, enters the air passage 90, is transmitted to the back surface side of the base plate 31a, and further drops to the blocking plate 92 to the upper surface thereof. There is a risk of adhesion. Therefore, for example, the blocking plate 92 may be provided so as to be inclined toward the lower outside in the radial direction instead of being flat, so that the attached liquid can quickly flow outward and be removed. In addition, a movable lid for automatically closing the air passage 90 may be provided during the liquid treatment. Further, the ventilation path 90 is not a vertical cylindrical shape as described above, and the cylinder may be inclined so that the opening on the front side of the base plate 31a is radially outward from the opening on the back side of the base plate 31a. Thereby, even if it enters into the ventilation path 90, it becomes easy to be pulled back to the front surface side by centrifugal force, so that the processing liquid is not easily transmitted to the back surface side of the base plate 31a.

  In the above embodiment, from the viewpoint of cost, the inert gas is not discharged during the drying process, but the present invention is not limited to this. The inert gas may be discharged from the gas discharge port 82 in parallel with supplying the gas from the air passage 90. As a result, the amount of gas supplied to the stagnation region increases, so that drying can be completed more quickly.

  In the above embodiment, the present invention has been described by taking the case where the lower surface of the wafer W is dried as an example. For example, the present invention can be applied to the case where the upper surface of the wafer W is dried. That is, in a system in which the wafer W is covered with the top plate, the same partial drying delay may occur due to the relationship between the upper surface of the wafer W and the lower surface of the top plate. In that case, it is possible to improve the uniformity of drying by providing the top plate with a vent hole similar to that of the above embodiment and supplying gas to a region where gas stagnation occurs in the structure.

20 Chamber 30 Substrate holding and rotating mechanism 40 Liquid discharge part 31a Base plate 90 Ventilation path

Claims (7)

A holding unit for holding the substrate in a horizontal position;
A base plate provided with the holding portion;
A rotating shaft for rotating the base plate;
A treatment liquid supply pipe provided at a tip of the liquid discharge port that is provided in the rotating shaft and discharges the treatment liquid toward the substrate;
A head that can arrange the liquid discharge port and cover at least a gap between the rotating shaft and the processing liquid supply pipe;
The base plate has an air passage that passes through one surface side and the other surface side of the base plate facing the substrate and generates an airflow flowing from the other surface side to the one surface side. A substrate liquid processing apparatus.   The air flow path is provided at a position where the airflow flowing on the one surface side is directed to a region where gas stagnation occurs in a region between the base plate and the substrate. 2. The substrate liquid processing apparatus according to 1.   The substrate liquid processing apparatus according to claim 2, wherein the gas stagnation region is a peripheral region at an end of the head.   The substrate liquid processing apparatus according to claim 1, wherein the head does not rotate.   5. The substrate liquid processing apparatus according to claim 1, wherein a plurality of the air passages are provided in the circumferential direction.   The substrate according to claim 1, further comprising a discharge port that discharges an inert gas on one surface side of the base plate when an air flow is generated by the air passage. Liquid processing equipment. A holding unit that holds the substrate in a horizontal posture, a base plate provided with the holding unit, a rotation shaft that rotates the base plate, and a rotation center of the rotation shaft, and discharges processing liquid toward the substrate. A treatment liquid supply pipe having a liquid discharge port at a tip thereof, and a circular head arranged at the center of the liquid discharge port and capable of covering at least a gap between the rotating shaft and the treatment liquid supply pipe. A substrate drying method for a substrate liquid processing apparatus comprising:
The base plate has an air passage that penetrates one surface side of the base plate facing the substrate and the other surface side,
A substrate drying method, wherein one surface of the substrate is dried using an airflow that flows from one surface side of the base plate to the other surface side that is generated as the shaft rotates.

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