JP2011086659A - Spin cleaner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve the cleaning quality of the lower surface (rear surface) of a disk, particularly a wafer, without increasing the weight of a spin table of a spin cleaner so much. <P>SOLUTION: In a spin cleaner 1, a cleaning fluid is fed on the upper and lower surfaces of a silicon wafer W from an upper-side cleaning fluid nozzle 6 and a lower-side cleaning fluid nozzle 12 while the silicon wafer W is supported horizontally on a spin table 4 and is rotated at high speed, and the both surfaces of the silicon wafer are cleaned. The spin cleaner 1 further includes a detachable flat rectifying plate 9 on the lower surface side of the silicon wafer W held by the spin table 4 to suppress adherence of a mist due to impurities to the lower surface of the silicon wafer W in cleaning, wherein the rectifying plate is held by the spin table 4 so as to be separated from the silicon wafer W. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a spin cleaning apparatus for cleaning a disk-shaped workpiece such as a silicon wafer.

  As a substrate to which the present invention is applied, a silicon wafer will be described as an example. In the silicon wafer manufacturing process used for semiconductor devices, the silicon wafer intended to produce a device structure only on one side has a single-sided mirror specification that mirrors only the device processed surface, and both mirror surfaces that are mirrored on both sides There are specifications. In particular, both mirror surface processing is mainly used for large-diameter silicon wafers having a diameter of 300 mmφ, and the cleanliness management of the back surface in addition to the device processed surface is beginning to be required.

  On the other hand, in the silicon wafer manufacturing process, one of the important processes is a cleaning process. Silicon wafer cleaning methods include a batch method in which a plurality of wafers are cleaned together with a carrier to be transferred, and a single wafer method in which a single wafer is cleaned. For large-diameter silicon wafers such as 300 mmφ, single-wafer cleaning machines, which are considered to have excellent cleaning ability, are widely used because of the strict requirements for standards for fine particles.

  However, the conventional single wafer cleaning machine is excellent in the cleaning ability of the surface which is a surface on which the device is manufactured, but is inferior in cleaning ability on the back surface as compared with the surface. Contaminants such as particles adhering to the back surface cause a decrease in yield, and therefore, it is a challenge to meet strict quality requirements in the future to perform cleaning so as not to leave contaminants on the back surface as much as possible.

  For this reason, conventionally, a cleaning method has been proposed in which a silicon wafer is held on a spin table and rotated at a high speed while supplying a cleaning liquid to the front surface and spraying and supplying a cleaning liquid to the back surface (for example, a patent) Reference 1-3).

JP-A-7-014817 JP-A-9-298181 JP-A-10-242114

  By the way, the cleaning process by the single wafer type spin cleaning apparatus includes etching by pouring cleaning liquid from the cleaning liquid nozzles for the front and back surfaces of the silicon wafer, and draining and drying steps using centrifugal force by high-speed rotation of the spin table. Consists of. In order to rotate the spin table at high speed, it is desirable that the spin table be as light as possible. From this point, the spin table used in the invention disclosed in Patent Document 2 is a disadvantage because it becomes a heavy disk-shaped member having a considerable thickness and thus becomes heavy.

  On the other hand, conventionally known spin tables include those having an opening as shown in FIG. 7 and those constituted by a plurality of arms extending in the radial direction from the center. For example, in the inventions disclosed in Patent Documents 1 and 3, a plurality of arms extending radially from the rotation shaft are used as the spin table. These are advantageous in terms of weight reduction of the spin table.

  However, when such a spin table having an opening or a radial arm is rotated at high speed, the mist of the cleaning solution is caught between the opening and the arm of the spin table on the back side of the wafer, and the back side of the wafer. There is a problem that it adheres as a contaminant. Contaminants adhering to the back surface may cause defects due to dust generation and contamination in the device process, and there is a concern that yield may be reduced.

  Therefore, the object of the present invention made by paying attention to these points is to improve the cleaning quality of the disc body, particularly the lower surface (back surface) of the wafer, without increasing the weight of the spin table by using a light current plate. An object of the present invention is to provide an improved spin cleaning apparatus.

The invention of the spin cleaning apparatus that achieves the above object is as follows:
Spin table for holding a disk-shaped object to be processed horizontally, rotation driving means for rotating the spin table, and upper surface cleaning liquid for supplying cleaning liquid to the upper surface of the object to be processed held on the spin table In a spin cleaning apparatus comprising a supply means and a lower surface cleaning liquid supply means for supplying a cleaning liquid to the lower surface of the substrate held by the spin table,
The spin table has a plurality of arms that are coupled to a rotation support shaft located on the lower surface and extend radially from the upper end of the rotation support shaft,
A detachable disk-shaped rectifying plate held by the spin table is provided on the lower surface side of the object to be processed held by the spin table so as to be separated from the object to be processed.

  In the spin cleaning apparatus, the rectifying plate is preferably made of a resin material, and more preferably made of vinyl chloride.

  The spin table preferably has a plurality of support members for supporting the substrate, and the rectifying plate preferably has a plurality of through holes into which the support members are inserted.

  Furthermore, it is preferable that the central portion of the current plate is provided with an opening for supplying the cleaning liquid to the lower surface of the object to be processed held on the spin table by the lower surface cleaning liquid supply means.

  According to the present invention, a detachable flat plate rectifying plate is provided on the lower surface (back surface) side of the wafer held by the spin table of the spin cleaning apparatus so as to be separated from the substrate by the spin table. Therefore, the quality of cleaning the lower surface of the substrate can be improved without significantly increasing the weight of the spin table.

It is a perspective view which shows the outline of the spin cleaning apparatus according to this invention. It is a longitudinal cross-sectional view of the principal part containing the spin table of the spin cleaning apparatus of FIG. It is a top view of a spin table. It is a top view which shows the state which attached the baffle plate to the spin table. It is a back surface particle map after spin washing, (a) is a case where a current plate is attached, (b) is a case without a current plate. It is a graph which shows distribution according to the number of particles of a wafer after spin cleaning, (a) is a case where a current plate is attached, and (b) is a case without a current plate. It is a top view of a spin table.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 is a perspective view showing an outline of a spin cleaning apparatus 1 according to an embodiment of the present invention. As shown in FIG. 1, the spin cleaning apparatus 1 has a cleaning tank 2 having a lid 2a for taking in and out a silicon wafer W as a substrate. A water receiving cup 3 having an open top is provided in the cleaning tank 2, and a spin table 4 for holding the silicon wafer W is provided on the inside thereof.

  Further, an upper cleaning liquid nozzle 6 is attached to one end of a nozzle arm 5 extending in the horizontal direction above the spin table, and the other end side of the nozzle arm is connected to a rotating shaft 7. An upper cleaning liquid supply pipe (not shown) is inserted through the rotation shaft 7 and the nozzle arm 5, and the cleaning liquid can be supplied from the upper cleaning liquid nozzle 6 onto the silicon wafer W supported by the spin table 4. Further, the rotation shaft 7 is rotationally driven by a motor (not shown), and the upper cleaning liquid nozzle 6 can be moved in the radial direction between the rotation center of the spin table 4 and the outer peripheral line above the silicon wafer W. The upper surface cleaning liquid supply means of the present invention includes a motor, a nozzle arm 5, an upper cleaning liquid nozzle 6, and a rotating shaft 7.

  FIG. 2 is a longitudinal sectional view of the main part including the spin table 4 of the spin cleaning apparatus 1 of FIG. FIG. 3 is a plan view of the spin table 4. The spin table 4 is preferably made of a light material having excellent chemical resistance, for example, vinyl chloride, and specifically, PVC (polyvinyl chloride), PEEK (polyetheretherketone), PBN (polybutylene). As shown in FIG. 3, for example, six arms extending in a radial direction between a circular inner ring part 4a and an outer ring part 4b centered on the center of rotation, as shown in FIG. It has the shape connected by the part 4c. As a result, the spin table 4 has a plurality of openings 4d that penetrate in the vertical direction and are surrounded by the inner annular portion 4a, the outer annular portion 4b, and the two adjacent arm portions 4c. Thus, the reason why the spin table 4 is configured only by the skeleton shape is to reduce the weight of the rotating part that rotates at high speed.

  Further, for example, six support pins 8 are provided vertically on the upper surface of the outer annular portion 4 b of the spin table 4. The support pin 8 has a step in the vertical direction, and has, for example, a shape in which the upper part of the cylinder is removed in a semi-cylindrical shape. As shown in FIG. 2, the silicon wafer W is supported on the steps of the support pins 8. The silicon wafer W is supported in a state of being separated from the upper surface of the spin table 4 by about 10 mm in the vertical direction. Note that the number of support pins 8 is not limited to six, and can be any number of three or more as long as the silicon wafer W can be fixedly held. The shape of the support pins 8 is not limited to a cylindrical shape, and may be any shape as long as it has a step and can support a silicon wafer, and may be a prismatic shape or an annular shape. In that case, a through-hole 9a of a rectifying plate 9 to be described later is also adapted to the contour shape of the cross section of the support pin 8.

  On the other hand, the inner annular portion 4 a of the spin table 4 is formed integrally with a rotation support shaft 10 that extends vertically downward from the rotation center of the spin table 4. The rotation spindle 10 is a substantially cylindrical member having a hollow portion extending along the central axis. The rotation support shaft 10 is connected to a rotation shaft (not shown) of the rotation mechanism 11 and is driven at a high speed around the rotation support shaft 10 by driving the rotation mechanism 11. Is rotated at high speed. The rotation driving means of the present invention includes a rotation support shaft 10 and a rotation mechanism 11.

  Further, four lower cleaning liquid nozzles 12 are provided on the inner side of the inner annular portion 4 a of the spin table 4. The lower cleaning liquid nozzle 12 is connected to the lower cleaning liquid supply pipe 13 inserted through the hollow portion of the rotary spindle 10 and injects the cleaning liquid toward the lower surface of the silicon wafer W placed on the spin table 4. Can be supplied. Note that the number of the lower cleaning liquid nozzles 12 is not limited to four, and may be more than four as long as the cleaning liquid can evenly clean the silicon wafer W when the spin table 4 rotates at high speed. The lower cleaning liquid supply means of the present invention includes a lower cleaning liquid nozzle 12 and a lower cleaning liquid supply pipe 13. The lower cleaning liquid nozzle 12 and the lower cleaning liquid supply pipe 13 are configured not to rotate regardless of the rotation of the spin table 4 and the rotation support shaft 10.

  On the other hand, a rectifying plate 9 is attached to the upper side of the spin table 4. FIG. 4 is a plan view showing a state in which the current plate 9 is attached to the spin table 4. The rectifying plate 9 is a detachable disk-shaped member having a radius substantially equal to or slightly larger than the outer periphery of the outer annular portion 4b of the spin table 4 and having a thickness of about 1 mm. It is made of a resin material that is lightweight and has excellent chemical resistance (alkali resistance, acid resistance). Further, the rectifying plate 9 has a plurality of through holes 9a for allowing the support pins 8 to pass through the outer peripheral portion. This makes it easy to assemble the current plate 9 on the spin table 4.

  Further, the rectifying plate 9 has an opening 9 b for allowing the cleaning liquid supplied from the lower cleaning liquid nozzle 12 to pass when supplying the cleaning liquid to the lower surface of the silicon wafer W held on the spin table 4. As a result, the cleaning liquid from the lower cleaning liquid nozzle can be easily sprayed onto the lower surface of the silicon wafer W.

  When the silicon wafer W is cleaned with the above-described configuration, the surface on which the device is formed is directed upward, and the current plate 9 disposed on the upper surface side of the spin table 4 as shown in FIGS. A silicon wafer W is placed on the substrate. Next, the rotation mechanism 11 is driven to rotate the spin table 4 through the rotation support shaft 10 within a rotation speed range of 100 to 2000 rpm. In this state, the upper cleaning liquid nozzle 6 and the lower cleaning liquid nozzle 12 respectively etch the upper surface and the lower surface of the silicon wafer, preferably simultaneously with the cleaning liquid. The present invention can be applied without depending on the cleaning liquid to be used. For example, ozone water, hydrofluoric acid solution, ammonia perwater, or the like can be used as the cleaning liquid. On the upper surface of the silicon wafer W, the cleaning liquid adhering to the upper surface of the silicon wafer W due to gravity is caused to flow toward the outer periphery of the silicon wafer W by centrifugal force, and the cleaning liquid is spread over the entire surface. Also on the lower surface side, the cleaning liquid adhering to the silicon wafer W by surface tension is spread over the entire surface by centrifugal force.

  After spin cleaning with the cleaning liquid, the spin table 4 is rotated at a higher speed to spin dry the silicon wafer W. Depending on the cleaning liquid to be used, after the spin cleaning with the cleaning liquid, rinsing is performed so as to remove the cleaning liquid remaining on the upper and lower surfaces of the silicon wafer W by spraying ultrapure water from the upper cleaning liquid nozzle 6 and the lower cleaning liquid nozzle 12. Processing may be performed.

  In the above description, the drainage of the cleaning liquid or ultrapure water that has flowed down from the silicon wafer W or blown off by centrifugal force is received by the water receiving cup 3 and discharged from the cleaning tank 1.

  Here, since the current plate 9 is provided below the silicon wafer W in the present invention, the mist containing impurities is wound up by the high speed rotation of the silicon wafer W, the spin table 4, etc. It is possible to prevent impurity particles from adhering to the lower surface of the silicon wafer W.

  As described above, according to this embodiment, the silicon wafer W held on the spin table 4 is thinly 1 mm thick held on the lower surface side of the silicon wafer W so as to be separated from and opposed to the silicon wafer W. Since the flat current plate 9 is provided, the cleanliness quality of the back surface of the silicon wafer W can be effectively improved without impairing the lightness of the spin table 4. Therefore, device defects due to dust generation and contamination from the back surface of the silicon wafer in the device process are reduced, and an improvement in the yield rate can be expected.

  Further, in the present invention, since the rectifying plate 9 is provided on the upper side of the spin table, the effect of protecting the spin table 4 and incidental equipment adjacent to the spin table 4 from corrosion by the cleaning liquid can also be achieved. Furthermore, since the rectifying plate 9 is detachable, it can be easily replaced against corrosion due to the cleaning liquid, and is excellent in maintainability. Further, since the rectifying plate 9 is made of vinyl chloride, which is an inexpensive, lightweight, and easy-to-process resin material, the rectifying plate 9 can be configured at low cost, and the energy cost for rotating the rectifying plate 9 at high speed can be reduced.

  In addition, this invention is not limited only to the said embodiment, Many deformation | transformation or a change is possible. For example, the spin table 4 has a configuration in which the inner annular portion 4a and the outer annular portion 4b are connected by the arm portion 4c, but the present invention is not limited to this, and various shapes are possible. The outer annular portion 4b of the spin table 4 may not be provided. In that case, the silicon wafer W and the current plate 9 may be supported by a support pin provided at the tip of the arm portion 4c.

  Although the lower cleaning liquid nozzle 12 is provided inside the inner annular portion 4a of the spin table and sprays the cleaning liquid on the back surface of the silicon wafer W, the present invention is not limited to this. The cleaning liquid can also be sprayed from the outside toward the center of the silicon wafer W in the gap between the silicon wafer W and the current plate 9.

  The silicon wafer is supported by the support pins 8 having a step, but is not limited thereto, and can be supported by various methods. For example, the silicon wafer W may be supported by providing a plurality of long support pins along the outer periphery of the silicon wafer W and a plurality of short support pins supporting the silicon wafer from below on the inside thereof.

  Although the thickness of the rectifying plate 4 is about 1 mm, an appropriate thickness can be selected as long as the shape does not deform when the spin table rotates at high speed. Moreover, although the material of the current plate is vinyl chloride, the material is not limited to this, and a light member having appropriate strength can be selected.

  Further, the present invention is not only applied to silicon wafers, but is a disk-shaped object such as a photomask glass substrate, a liquid crystal display glass substrate, an optical disk substrate, etc., and requires cleaning of the back surface. It can be applied to the cleaning of various workpieces.

  1-4 using the spin cleaning apparatus 1 according to the embodiment and a conventional spin cleaning apparatus (a spin cleaning apparatus in which the rectifying plate 9 is removed from the spin cleaning apparatus 1) to which the rectifying plate 9 is not attached. The silicon wafer was cleaned. The cleaning conditions at this time are cleaning processes in which an oxidation cleaning process using ozone water and an acid cleaning process using a hydrofluoric acid solution are repeated, and the cleaning is performed repeatedly for 3 minutes while rotating the spin table at 500 rpm. It is.

  The back surface of the silicon wafer after spin cleaning obtained in the examples and comparative examples was measured using a particle measuring device (manufactured by KLA-Tencor: Surfscan SP1), and the back surface particle map of the detected silicon wafer is shown in FIG. ) And (b). FIG. 5A shows a case where the current plate 9 is attached (Example), and FIG. 5B shows a case where the current plate 9 is not present (Comparative Example). Comparing the two, in the comparative example cleaned with a spin cleaning device without the rectifying plate 9, the mist pattern that seems to have been caught from the unevenness of the silicon wafer holding portion or the opening of the spin table 4 was observed over the entire lower surface of the wafer. On the other hand, in the wafer cleaned using the spin cleaning apparatus 1 of the present embodiment with the rectifying plate 9 attached, a mist pattern was seen only on a part of the lower surface, and a remarkable improvement effect was recognized. .

  Furthermore, the distribution according to the number of particles of the silicon wafer after spin cleaning is shown in FIG. In this graph, 20 silicon wafers were cleaned using the spin cleaning apparatus of this example and comparative example, and the number of particles adhering to the back surface of each silicon wafer was measured using a particle measuring device (manufactured by KLA-Tencor: Measured by Surfscan SP1). FIG. 6A shows the case where the current plate 9 is attached (Example), and FIG. 6B shows the case where the current plate is not present (Comparative Example). As apparent from FIGS. 6A and 6B, in the comparative example, the number of particles is distributed to about 25 to 80, whereas in the experiment using the spin cleaning apparatus 1 according to the example, the particle The numbers are distributed between 10 and 25.

  Accordingly, it was confirmed that the adhesion of impurity particles to the back surface of the silicon wafer W can be reduced as compared with the comparative example by using the spin cleaning apparatus 1 according to the embodiment shown in FIGS.

  According to the present invention, it is possible to provide a spin cleaning apparatus that improves the quality of cleaning the lower surface of an object to be processed without impairing the weight reduction of the spin table.

DESCRIPTION OF SYMBOLS 1 Spin cleaning apparatus 2 Cleaning tank 3 Water receiving cup 4 Spin table 4a Inner ring part 4b Outer ring part 4c Arm part 4d Opening part 5 Nozzle arm 6 Upper washing | cleaning liquid nozzle 7 Rotating shaft 8 Support pin 9 Current plate 9a Through-hole 9b Opening 10 Rotating spindle 11 Rotating mechanism 12 Lower cleaning liquid nozzle 13 Lower cleaning liquid supply pipe W Silicon wafer

Claims (5)

Spin table for holding a disk-shaped object to be processed horizontally, rotation driving means for rotating the spin table, and upper surface cleaning liquid for supplying cleaning liquid to the upper surface of the object to be processed held on the spin table In a spin cleaning apparatus comprising a supply means and a lower surface cleaning liquid supply means for supplying a cleaning liquid to the lower surface of the substrate held by the spin table,
The spin table has a plurality of arms that are coupled to a rotation support shaft located on the lower surface and extend radially from the upper end of the rotation support shaft,
A spin cleaning comprising: a detachable disc-shaped rectifying plate held by the spin table so as to be separated from the workpiece, on a lower surface side of the workpiece to be held by the spin table. apparatus.   The spin cleaning apparatus according to claim 1, wherein the current plate is made of a resin material.   The spin cleaning apparatus according to claim 2, wherein the resin material is vinyl chloride.   The spin table has a plurality of support members for supporting the substrate, and the rectifying plate has a plurality of through holes into which the support members are inserted. The spin cleaning apparatus according to one item.   The center part of the said baffle plate was equipped with the opening part for supplying a cleaning liquid to the lower surface of the to-be-processed object hold | maintained at the said spin table by the said lower surface cleaning liquid supply means, Any one of Claims 1-4 characterized by the above-mentioned. A spin cleaning apparatus according to claim 1.

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