JP2006310697A - Vacuum chuck - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a vacuum chuck capable of preventing deformation of a substrate during vacuum holding without increasing a contact area with the substrate. <P>SOLUTION: In the vacuum chuck 10, a supporting unit 32 in a projected shape for fitting to a lower face of a substrate is formed on a mounting face 31. A region on the mounting face 31 other than the supporting unit 32 is divided by the supporting unit 32 into an air released region 33 and a pressure reduction region 34. The air released region 33 is four sectorial regions surrounded by the supporting unit 32, and a joining through-hole 35 joined mutually to the atmosphere around the chuck is drilled at each air released region 33. The pressure reduced region 34 includes an annular region 34a which is formed annularly around the circumferential part of the mounting face 31, and a joining through region 34b which extends continuously from the center of the mounting face 31 to the annular region 34a. At the central part, a sucking hole 36 is provided for performing vacuum suction. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  In the present invention, a semiconductor substrate, a glass substrate for a liquid crystal display device, a glass substrate for a photomask, a substrate for an optical disk or the like (hereinafter simply referred to as “substrate”) is placed, and the lower surface is vacuum-sucked to place the substrate. The present invention relates to a suction chuck for suction holding.

  In a rotary coating processing apparatus (spin coater) that performs a resist coating process while rotating a substrate, a photoresist solution is discharged onto the upper surface of a substrate that is rotated at a high speed, and the photoresist solution is removed by a centrifugal force accompanying the rotation of the substrate. It is spread and applied evenly. At this time, the vicinity of the central portion on the lower surface side of the substrate is vacuum-sucked by the suction chuck, whereby the rotational driving force of the motor is transmitted to the substrate and the substrate is prevented from flying even by high-speed rotation.

  As a suction chuck of the type that holds the substrate by such vacuum suction, those disclosed in Patent Documents 1 and 2 have been used. That is, a plurality of ring-shaped support portions are provided concentrically on the mounting surface of the suction chuck, and a groove between adjacent ring-shaped support portions is communicated with the vacuum suction port so that the lower surface of the substrate is brought into contact with the ring-shaped support portion. In general, a suction chuck of a type that sucks and holds a substrate by reducing the groove between the ring-shaped support portions in a reduced pressure state has been widely used. A suction chuck of the type that vacuum-sucks the back surface of the substrate is used not only for a rotary coating processing apparatus but also for a developing apparatus and a cleaning apparatus, as well as a grinding apparatus (see Patent Document 3).

  However, when such a suction chuck is used, there is a problem that contamination (suction marks) tends to occur on the back surface of the substrate. This is because the support portion occupies a considerable area of the placement surface of the suction chuck, and when sucking and holding, they are all brought into contact with and pressed against the lower surface of the substrate. This is because particle transfer is likely to occur.

  On the other hand, in recent years, the size of substrates has increased, and semiconductor wafers are shifting from φ200 mm to φ300 mm. When the size of the substrate increases, the mounting surface of the suction chuck must be increased for reliable substrate holding and driving force transmission. If it does so, the area (namely, contact area) of a support part will also become larger, and the problem that the contamination to the back surface of a board | substrate increases will arise.

  For this reason, a suction chuck in which a contact area is reduced by disposing support portions in a dotted shape on the mounting surface has also been proposed (see, for example, Patent Document 4). According to this, even if the mounting surface of the suction chuck is increased with an increase in the size of the substrate, an increase in the contact area can be suppressed, so that an increase in contamination on the lower surface of the substrate can be prevented. .

JP-A 64-75072 JP-A-10-112495 JP 2004-114184 A Japanese Patent Laid-Open No. 7-21678

  However, reducing the contact area means increasing the reduced pressure region that is in a reduced pressure state during vacuum adsorption. FIG. 6 is a diagram schematically showing a state when the substrate is sucked and held by such a low contact area type suction chuck. Substrate support portions 102 are arranged in a dotted pattern on the upper surface (mounting surface) of the suction chuck 101, and a region other than the substrate support portion 102 on the mounting surface is a reduced pressure region. In the reduced pressure region, a differential pressure with respect to the external pressure acts on the substrate W during adsorption holding. When the contact area of the substrate support portion 102 decreases and the reduced pressure region increases, the substrate W is greatly bent between the substrate support portions 102 due to a differential pressure from the external air pressure, as shown in FIG.

  When the resist coating process is performed while rotating the substrate W that is greatly bent as shown in FIG. 6, there is a problem that a so-called coating unevenness is caused in which the photoresist solution cannot be uniformly applied to the upper surface of the substrate W.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a suction chuck that can suppress deformation of the substrate during suction holding without increasing the contact area with the substrate.

  In order to solve the above-mentioned problem, the invention of claim 1 is a suction chuck for sucking and holding a substrate by vacuum suction of the lower surface of the substrate, and a mounting surface for mounting the substrate; And a support portion that is provided in a convex shape on the mounting surface and supports the substrate by contacting the lower surface of the substrate placed on the mounting surface. Partitioning into an open area, the decompression area and the atmosphere release area are closed areas surrounded by the support, and a suction port communicating with an external vacuum suction means is formed in the decompression area, and the atmosphere release area A communication hole that communicates with the atmosphere around the chuck, and an annular region that is annularly provided along the peripheral edge of the placement surface and the annular region from the center of the placement surface. Continuous communication area A.

  According to a second aspect of the present invention, in the suction chuck according to the first aspect of the invention, the communication area is linearly arranged from the center of the mounting surface toward the annular area.

  According to a third aspect of the present invention, in the suction chuck according to the first or second aspect of the present invention, the communication area is arranged radially from the center of the mounting surface toward the annular area.

  According to a fourth aspect of the present invention, in the suction chuck according to any one of the first to third aspects, the suction port is formed in a central portion of the mounting surface.

  According to the first aspect of the present invention, the air release region that does not directly contribute to the suction holding of the substrate is formed on the mounting surface of the suction chuck, and the area of the decompression region is increased without increasing the contact area with the substrate. It is also possible to suppress substrate deformation during adsorption holding.

  According to the invention of claim 2, since the communication area is linearly arranged from the center portion of the mounting surface toward the annular area, the entire decompression area can be quickly brought into a decompressed state.

  According to the invention of claim 3, since the communication area is arranged radially from the center portion of the mounting surface toward the annular area, the entire decompression area can be quickly brought into a decompressed state.

  According to the invention of claim 4, since the suction port is formed in the center portion of the mounting surface, even the warped substrate is sequentially sucked along the communication region from the center portion toward the peripheral portion. The chuck is corrected to a flat state and is sucked and held.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a cross-sectional view of an essential part showing an example of a substrate processing apparatus in which a suction chuck according to the present invention is incorporated. The substrate processing apparatus 1 is a rotary coating processing apparatus that performs a resist coating process while rotating a substrate W that is a substantially circular semiconductor wafer.

  The substrate processing apparatus 1 includes a suction chuck 10 that vacuum-sucks and holds the substrate W in a horizontal posture by vacuum suction of the lower surface of the placed substrate W. The suction chuck 10 is attached to an upper end of a rotating shaft 2 that rotates about an axis along the vertical direction by driving of an electric motor (not shown) so as to be integrally rotatable. Further, the suction chuck 10 is communicated with a vacuum suction means such as a vacuum pump through a hollow rotating shaft 2.

  Further, the substrate processing apparatus 1 includes a cup 5 and a resist discharge nozzle 9. The cup 5 surrounds the periphery of the substrate W sucked and held by the suction chuck 10. The cup 5 collects the processing liquid (here, photoresist liquid) scattered from the rotating substrate W and guides it to the lower drainage port 5a. The resist discharge nozzle 9 is connected in communication with a resist feed unit (not shown), and discharges the resist fed from the resist feed unit to the vicinity of the center of the upper surface of the rotating substrate W.

  When the resist coating process is performed by the substrate processing apparatus 1, first, the substrate W is placed on the placement surface of the suction chuck 10 and held by vacuum suction. Thereafter, the photoresist solution is discharged from the resist discharge nozzle 9 to the center of the upper surface of the rotating substrate W while rotating the substrate W around the vertical axis via the rotating shaft 2 and the suction chuck 10. The dropped photoresist solution spreads uniformly on the upper surface of the substrate W by a centrifugal force accompanying the rotation of the substrate W to form a resist film. Note that the photoresist liquid scattered from the substrate W is received by the cup 5 and discharged from the liquid discharge port 5a.

  Next, the suction chuck 10 will be described in more detail. FIG. 2 is an external perspective view of the suction chuck 10. 3 is a plan view of the suction chuck 10 as viewed from above, and FIG. 4 is a side sectional view of the suction chuck 10 as viewed along the line V-V in FIG.

  The suction chuck 10 is composed of a substrate mounting portion 30 and a connection shaft 20. The substrate mounting portion 30 and the connecting shaft 20 are integrally formed of, for example, a peak material (polyether ether ketone: PEEK) that is a polymer compound. The material of the suction chuck 10 is not limited to the peak material. Further, in order to lower the insulating property of the suction chuck 10 and prevent static charge, conductive fine powder such as carbon may be mixed with the peak material.

  The substrate platform 30 is a disk-shaped member having a diameter smaller than the diameter of the substrate W. A cylindrical connection shaft 20 is provided vertically at the center of the lower surface of the substrate platform 30. The outer diameter of the connection shaft 20 is smaller than the diameter of the substrate platform 30. A fitting hole 21 having an inner diameter substantially the same as the outer diameter of the rotating shaft 2 is formed at the lower end of the connecting shaft 20, and the upper end portion of the rotating shaft 2 is inserted therein. A projection formed on the outer periphery of the upper portion of the rotating shaft 2 engages with the inside of the insertion hole 21 so that the rotating shaft 2 and the suction chuck 10 inserted here rotate integrally. Notch is engraved. Instead of providing the notch inside the insertion hole 21, the connecting shaft 20 is attached to the upper end of the rotating shaft 2 with a separate connecting pin so that the rotating shaft 2 and the suction chuck 10 rotate integrally. Anyway.

  The upper surface of the substrate platform 30 is a placement surface 31 on which the substrate W is placed. On the mounting surface 31, a support portion 32 is provided in a convex shape. In the present embodiment, the support portion 32 is formed in an annular shape along the peripheral end portion of the mounting surface 31, and also forms a sector shape with four central angles of 90 ° inside the annular support portion 32. As shown in FIG. That is, four fan-shaped parts with a central angle of 90 ° are formed inside an annular support part 32 protruding along the peripheral end of the mounting surface 31, and the peripheral parts (fan-shaped The arc and the radius are also constituted by the support portion 32 protruding on the mounting surface 31. These four sectors are formed around the rotation axis X of the suction chuck 10 every 90 °. Further, the annular support portion 32 and the fan-shaped support portion 32 have the same height. Therefore, when the substrate W is placed on the placement surface 31, all of the annular support portion 32 and the fan-shaped support portion 32 come into contact with the lower surface of the substrate W to support the substrate W.

  A region of the placement surface 31 other than the support portion 32 is partitioned into two regions by the support portion 32. First, an area surrounded by the fan-shaped support portion 32 is an air release area 33. The air release area 33 is a fan-shaped area having a central angle of 90 °, and four are provided on the placement surface 31. Next, the area excluding the atmosphere release area 33 is a decompression area 34. As shown in FIGS. 2 and 3, the atmosphere release region 33 and the decompression region 34 are closed regions surrounded by the support portion 32. Further, when the substrate W is placed on the placement surface 31, neither the atmosphere release region 33 nor the decompression region 34 is in contact with the lower surface of the substrate W.

  Further, the decompression region 34 has an annular region 34a and a communication region 34b. The annular region 34 a is an annular groove-shaped region formed between the annular support portion 32 and the arc of the fan-shaped support portion 32. That is, the annular region 34 a is inscribed in the annular support portion 32 and is annularly provided along the peripheral edge portion of the placement surface 31. On the other hand, the communication area 34b is a linear groove area located between the fan-shaped support portions 32. The communication region 34b is continuously formed linearly from the center of the placement surface 31 toward the annular region 34a, and is arranged in a cross shape in this embodiment.

  One communication hole 35 is provided in each of the four atmospheric open areas 33. The communication hole 35 is drilled from the upper surface (mounting surface 31) of the substrate platform 30 to the lower surface. Therefore, in the atmosphere release region 33, the upper surface side atmosphere and the lower surface side atmosphere of the substrate platform 30 are communicated through the communication hole 35.

  A suction port 36 is formed in the decompression area 34. The suction port 36 is formed in one place at the center of rotation of the mounting surface 31, that is, at the center of the cross shape of the decompression region 34. The upper end portion of the suction port 36 opens to the placement surface 31 side, and the lower end portion communicates with the insertion hole 21 of the connection shaft 20. The rotary shaft 2 inserted into the insertion hole 21 has a hollow cylindrical shape, and the hollow portion communicates with a vacuum suction means such as a vacuum pump. Accordingly, the suction port 36 communicates with the vacuum suction means outside the chuck, and when the vacuum suction means is operated, a negative pressure is applied to the suction port 36 through the hollow portion of the rotating shaft 2 and the fitting hole 21. be able to.

  When the substrate W is placed on the placement surface 31 of the suction chuck 10 having the above configuration, the support portion 32 comes into contact with the lower surface of the substrate W. At this time, neither the atmosphere release region 33 nor the decompression region 34 is in contact with the lower surface of the substrate W. When the vacuum suction means is operated in this state, the atmosphere in the decompression region 34 is sucked from the suction port 36. In the present embodiment, the suction port 36 is formed at the center of the cross shape of the communication region 34b. First, the atmosphere in the annular region 34a is sucked after the atmosphere is sucked in order from the center of the communication region 34b. As a result, the space formed by the reduced pressure region 34 and the lower surface of the substrate W is in a reduced pressure state, and the substrate W is pressed against the support portion 32 by the differential pressure with respect to the atmosphere around the suction chuck 10 (atmospheric pressure). In this way, the substrate W is sucked and held by the suction chuck 10.

  At this time, in the atmosphere release region 33, the atmosphere on the placement surface 31 side and the lower surface side atmosphere are communicated through the communication hole 35. Accordingly, the atmospheric pressure in the space formed by the atmosphere release region 33 and the lower surface of the substrate W is equal to the atmospheric pressure around the suction chuck 10, and no differential pressure is generated in the atmosphere release region 33. As a result, when viewed from the side of the substrate W sucked and held by the suction chuck 10, the area facing the decompression region 34 of the placement surface 31 receives pressure from the surrounding atmosphere and is pressed against the support portion 32. In the area facing the air release area 33, no pressure is applied and the area is stress free. In other words, the atmosphere release region 33 is not a region in contact with the substrate W, a region in which an adsorption pressure is applied to the substrate W, and a region that does not directly contribute to the adsorption holding of the substrate W.

  In the conventional suction chuck, the mounting surface is composed only of the decompression region and the support portion. Therefore, if the area of the support portion is reduced, the area of the decompression region is increased, and conversely, if the area of the decompression region is reduced, the support portion. The area of was larger. As described above, when the area of the reduced pressure region is increased, the substrate W is greatly deformed to cause coating unevenness, and when the area of the support portion is increased, problems such as contamination due to an increase in the contact area occur.

  Therefore, in the present embodiment, the atmosphere release region 33 that does not directly contribute to the suction holding of the substrate W is formed on the placement surface 31 of the suction chuck 10 to reduce the pressure without increasing the contact area with the substrate W. An increase in the area of the region 34 is also suppressed. Since the increase in the contact area between the suction chuck 10 and the substrate W can be suppressed by forming the air release region 33, damage (scratch) and contamination transfer that the lower surface of the substrate W receives from the support portion 32 can be minimized. It becomes.

  Further, since the increase in the area of the decompression region 34 can be suppressed by forming the atmosphere release region 33, the area where the substrate W is subjected to deformation stress at the time of suction can be reduced, and as a result, deformation of the substrate W at the time of suction holding can be reduced. Therefore, it is possible to improve the problem of coating unevenness during the resist coating process. Furthermore, reducing the area where the substrate W is subjected to deformation stress also leads to a reduction in the risk of damaging and destroying a device formed on the upper surface of the substrate W during suction holding.

  By the way, in the present embodiment, the decompression region 34 is formed in an annular shape around the periphery of the mounting surface 31 in an annular manner, and the center of the mounting surface 31 is continuously linearly directed toward the annular region 34a. The communication area 34b extends in a shape. The reason for this is as follows. First, at the time of suction and holding, the suction force is actually generated at the contact portion between the support portion 32 surrounding the decompression region 34 and the substrate W. In order to reliably transmit the torque of the rotating shaft 2 to the substrate W, it is necessary to make the portion that generates the suction force an annular shape having a diameter as large as possible. That is, by providing the annular region 34a in an annular shape along the peripheral edge of the mounting surface 31 as in the present embodiment, the torque of the rotating shaft 2 can be reliably transmitted to the substrate W, and at the time of starting or stopping the rotation. At this time, it is possible to prevent the substrate W from coming off or slipping from the suction chuck 10.

  In addition, the actual substrate W, particularly the substrate W on which several layers have already been formed, tends to warp upward or downward as a property of itself. Even such a substrate W must be held flat in the horizontal direction in order to prevent defects such as coating unevenness during the resist coating process. According to the suction chuck 10 of the present embodiment, since suction is performed from the suction port 36 provided at the center of the mounting surface 31, in the unsteady state, the suction force in the vicinity of the suction port 36 is the strongest and the warped substrate W is warped. Even so, the vicinity of the center is first attracted to the center of the mounting surface 31. Since the communication region 34b that generates the suction force continuously extends from the center portion of the placement surface 31 toward the annular region 34a, the substrate W is sequentially sucked from the center portion toward the peripheral portion. It becomes. Therefore, the substrate W can be surely corrected to a flat state and adsorbed to the mounting surface 31 without causing a vertically bent portion.

  Further, since the communication region 34b extends in a straight line from the center of the mounting surface 31 toward the annular region 34a, the atmosphere of the annular region 34a can be smoothly exhausted from the suction port 36. . As a result, the annular region 34a can be brought into a steady decompression state similar to that of the communication region 34b within a short time after the operation of the vacuum suction means of the substrate processing apparatus 1. In the substrate processing apparatus 1, the suction pressure is monitored in order to check whether or not the suction chuck 10 has reliably sucked the substrate W, but the sensor is closer to the vacuum suction means than the rotary shaft 2. It is installed on the side. Therefore, if the time from when the vacuum suction means starts operating until the annular region 34a is in the reduced pressure state is long, the substrate processing apparatus is actually not sucked by the suction chuck 10 yet. There is a possibility that a trouble such as 1 is judged to have attracted and starts rotating. According to the present embodiment, the communication area 34b extends in a cross shape linearly from the center of the mounting surface 31 toward the annular area 34a, and the annular area 34a is rapidly brought into a steady decompression state. Such a problem is solved.

  While the embodiments of the present invention have been described above, the present invention is not limited to the above examples. For example, in the above embodiment, the mounting surface 31 is divided into four around the rotation axis X so as to provide four fan-shaped atmospheric open areas 33 having a central angle of 90 °. However, as shown in FIG. Eight fan-shaped atmospheric open areas 33 having a central angle of 45 ° may be provided by dividing into eight. In the example illustrated in FIG. 5, the communication area 34 b is disposed in a US shape from the center of the placement surface 31 toward the annular area 34 a in correspondence with the eight open air areas 33. . Further, the suction port 36 is provided not in the center of the placement surface 31 but in the middle of the passage of the communication region 34b. The suction port 36 is connected in communication with the insertion hole 21. Each of the eight air release regions 33 is provided with a communication hole 35 communicating with the chuck peripheral atmosphere. Even if it is such a structure, the effect similar to the said embodiment can be acquired.

  Alternatively, the mounting surface 31 may be divided into six around the rotation axis X to provide six fan-shaped atmospheric open areas 33 having a central angle of 60 °. In short, the atmosphere release region 33 that does not directly contribute to the adsorption holding of the substrate W is formed on the mounting surface 31 and is annularly formed along the peripheral portion of the mounting surface 31 as the decompression region 34 that directly participates in the adsorption holding. If the annular region 34a provided around and the communication region 34b continuously extending from the center of the mounting surface 31 toward the annular region 34a are provided, the same effect as in the above embodiment can be obtained. And according to the formation aspect of the air release area | region 33, the communication area | region 34b will be arrange | positioned radially from the center part of the mounting surface 31 toward the cyclic | annular area | region 34a.

  In order to achieve both the effects of suppressing the increase in the contact area and preventing the deformation of the substrate W at the time of suction and holding, it is preferable to form the atmosphere release region 33 at least half of the entire area of the placement surface 31. However, if the area ratio of the atmospheric open area 33 that does not contribute to the adsorption is too large, the necessary adsorption holding force cannot be obtained, so the area of the atmospheric open area 33 is 90% or less of the entire area of the mounting surface 31. Things are preferable. In order to suppress the deformation of the substrate W while ensuring the necessary suction holding force, the groove width of the decompression region 34 is preferably set to 0.5 mm to 5.0 mm.

  In the above embodiment, the suction port 36 may be provided in the middle of the passage of the communication region 34b as shown in FIG. 5, or the suction port 36 may be provided at the center of the placement surface 31 in the example of FIG. good.

  In the above-described embodiment, the substrate processing apparatus 1 performs the resist coating process. However, the suction chuck according to the present invention is applied to a device that vacuum-holds and rotates the substrate, for example, a cleaning processing device or a development processing device. You may do it.

  Furthermore, the substrate W to be held by the suction chuck according to the present invention is not limited to a semiconductor wafer, and may be a glass substrate for a liquid crystal display device.

It is principal part sectional drawing which shows an example of the substrate processing apparatus with which the suction chuck concerning this invention was incorporated. It is an external appearance perspective view of a suction chuck. It is the top view which looked at the adsorption chuck from the upper surface. It is the sectional side view which looked at the adsorption chuck along the VV line of FIG. It is a top view which shows the other example of a suction chuck. It is a figure which shows typically a state when a board | substrate is adsorbed and hold | maintained with the low contact area type adsorption chuck.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Substrate processing apparatus 2 Rotating shaft 5 Cup 9 Resist discharge nozzle 10 Adsorption chuck 20 Connection shaft 30 Substrate placement part 31 Placement surface 32 Support surface 33 Atmospheric release region 34 Decompression region 34a Annular region 34b Communication region 35 Communication hole 36 Suction port W substrate

Claims (4)

A suction chuck that sucks and holds the substrate by vacuum suction of the lower surface of the placed substrate,
A mounting surface for mounting the substrate;
A support portion that is provided in a convex shape on the mounting surface and supports the substrate by contacting the lower surface of the substrate placed on the mounting surface;
With
The mounting surface is partitioned into a decompression region and an air release region by the support part,
The decompression region and the atmosphere release region are closed regions surrounded by the support part,
In the reduced pressure area, a suction port communicating with an external vacuum suction means is formed,
In the air release region, a communication hole communicating with the atmosphere around the chuck is formed,
The decompression region has an annular region that is annularly provided along a peripheral portion of the placement surface and a communication region that is continuously provided from the center of the placement surface toward the annular region. Features a suction chuck. The suction chuck according to claim 1,
The suction chuck according to claim 1, wherein the communication region is linearly arranged from the center of the mounting surface toward the annular region. The suction chuck according to claim 1 or 2,
The suction chuck according to claim 1, wherein the communication area is arranged radially from the center of the mounting surface toward the annular area. The suction chuck according to any one of claims 1 to 3,
The suction chuck according to claim 1, wherein the suction port is formed in a central portion of the mounting surface.

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