JP2018082037A - Chuck cable mechanism - Google Patents

Abstract

An object of the present invention is to prevent deformation of a plate-like object due to pressure acting on the plate-like object while holding the plate-like object well.
A chuck table mechanism (100) includes a holding surface (43) for sucking and holding a wafer (W) and a chuck table (42) having a communication path (42b) communicating with the holding surface, and a suction to the communication path. A suction source (102) connected via the passage (101), a pressure detection means (107) disposed in the suction passage near the communication passage and detecting the pressure in the suction passage, and a pressure detection means of the suction passage And a release path (108) that branches between the suction source and the air through the control valve (109), and a control means for controlling the valve opening degree of the control valve based on a detection signal from the pressure detection means (111). The control means controls the valve opening degree of the control valve so as to suck and hold at a predetermined pressure according to the wafer to which the protective tape (T) is adhered.
[Selection] Figure 3

Description

  The present invention relates to a chuck table mechanism that holds a plate-like object when the plate-like object such as a semiconductor wafer is ground and polished.

  In order to form a thin semiconductor chip, there is a technique in which a protective tape is attached to the surface of a semiconductor wafer, and then the back surface of the semiconductor wafer is ground to a desired thickness by grinding with a grinding wheel (see, for example, Patent Document 1). ). When irregularities such as bumps are formed on the surface of the semiconductor wafer to be ground, a protective tape for grinding having an adhesive layer is adhered to the surface, and the adhered protective tape for grinding is formed into an irregular shape along the irregularities. Can be considered. And after sticking a protective tape in this way and making it the shape which follows an unevenness | corrugation, the protective tape side of a semiconductor wafer is suction-held on the chuck table of a grinding device, and grinding is implemented.

JP 2013-021017 A

  However, when the protective tape is stuck along the unevenness as described above, when the suction force on the chuck table is increased, the protective tape along the unevenness is deformed so as to follow the flat upper surface of the chuck table. At this time, a portion of the protective tape stuck so as to be recessed between the bumps is peeled off from the surface of the semiconductor wafer to generate bubbles, and contamination such as contamination generated by grinding enters the bubbles and causes contamination. There is a problem.

  The present invention has been made in view of such a point, and provides a chuck table mechanism that can prevent deformation on the plate-like object side by pressure acting on the plate-like object while holding the plate-like object well. One of the purposes is to provide it.

  A chuck table mechanism according to an aspect of the present invention includes a chuck table having a holding surface for sucking and holding a plate-like object and a communication path communicating with the holding surface, and a suction source connected to the communication path via the suction path. A pressure detection means disposed in the suction passage near the communication passage to detect the pressure in the suction passage, and is branched between the pressure detection means of the suction passage and the suction source. And a release path that is released to the atmosphere via the control valve, and a control means that controls the valve opening of the control valve based on a detection signal from the pressure detection means. The valve opening degree of the control valve is controlled so as to be sucked and held at a predetermined pressure.

  In this configuration, it is possible to adjust the pressure for sucking and holding the plate-like object by controlling the control valve that can be released into the atmosphere through the suction passage. Thereby, for example, in order to process the back surface of the plate-like object to which the protective tape is attached along the unevenness of the front surface, when the protective tape side of the plate-like object is sucked and held by the holding surface, it is attached along the unevenness. The shape of the protective tape can be maintained. Therefore, it can be avoided that the protective tape along the uneven surface follows the holding surface as in the past, and the generation of air bubbles between the protective tape and the plate-like object is prevented, so that intrusion of processing waste into the air bubbles is eliminated. be able to. Moreover, the suction pressure can be adjusted in accordance with the plate-like object so that the plate-like object is not displaced by the suction holding with the chuck table even if an external force accompanying the processing of the plate-like object is applied.

  According to the present invention, the valve opening degree of the control valve is controlled so that the plate-like object is sucked and held at a predetermined pressure. Can be prevented from being deformed.

It is a perspective view of the grinding-polishing apparatus of this Embodiment. It is a schematic block diagram of a chuck table mechanism and a conveyance pad, and is explanatory drawing of a mounting step. FIG. 3A is an explanatory diagram of a control valve adjustment step, and FIG. 3B is an explanatory diagram showing a state in which bubbles are generated by the conventional holding method.

  Hereinafter, a grinding and polishing apparatus provided with a chuck table mechanism according to the present embodiment will be described with reference to the accompanying drawings. FIG. 1 is a perspective view of the grinding and polishing apparatus of the present embodiment. The chuck table mechanism can be applied to a processing apparatus including a chuck table having a holding surface, and is not limited to the grinding and polishing apparatus shown in FIG.

  As shown in FIG. 1, the grinding and polishing apparatus 1 is a full-auto type processing apparatus, which carries in a semiconductor wafer W (hereinafter referred to as “wafer W”), a rough grinding process, a finish grinding process, and a polishing process. A series of operations including processing, cleaning processing, and unloading processing are configured to be performed fully automatically. The wafer W is formed in a substantially disc shape, and is carried into the grinding and polishing apparatus 1 while being accommodated in the cassette CT. The wafer W may be a workpiece made of a plate to be ground and polished, may be a semiconductor substrate such as silicon or gallium arsenide, or may be an inorganic material substrate such as ceramic, glass, or sapphire, Further, it may be a package substrate of a semiconductor product. A plurality of hemispherical protrusions B (see FIG. 2) such as bumps are formed on the surface of the wafer W, and a protective tape T is attached. In addition, the convex part B is not restricted to a bump, It does not necessarily need to be formed.

  On the front side of the base 11 of the grinding / polishing apparatus 1, a pair of cassettes CT in which a plurality of wafers W are accommodated are placed. Behind the pair of cassettes CT is a cassette robot 16 for taking wafers W in and out of the cassettes CT. A positioning mechanism 21 that positions the unprocessed wafer W and a cleaning mechanism 26 that cleans the processed wafer W are provided on both diagonally rear sides of the cassette robot 16. Between the positioning mechanism 21 and the cleaning mechanism 26, there are provided loading means 31 for loading the unprocessed wafer W onto the chuck table 42 and unloading means 36 for unloading the processed wafer W from the chuck table 42. . The chuck table 42 constitutes a chuck table mechanism 100 (see FIG. 2) described later.

  The cassette robot 16 is configured by providing a hand portion 18 at the tip of a robot arm 17 composed of a multi-node link. In the cassette robot 16, the wafer W before grinding / polishing is transferred from the cassette CT to the positioning mechanism 21, and the wafer W after grinding / polishing is transferred from the cleaning mechanism 26 to the cassette CT. The positioning mechanism 21 is configured by arranging a plurality of positioning pins 23 that can move forward and backward with respect to the center of the temporary table 22 around the temporary table 22. In the positioning mechanism 21, the center of the wafer W is positioned at the center of the temporary placement table 22 by causing a plurality of positioning pins 23 to abut on the outer peripheral edge of the wafer W placed on the temporary placement table 22.

  The carry-in means 31 is configured by providing a carry-in pad 33 at the tip of a carry-in arm 32 that can turn on the base 11. In the carry-in means 31, the wafer W is lifted from the temporary placement table 22 by the carry-in pad 33, and the carry-in pad 33 is turned by the carry-in arm 32 to carry the wafer W into the chuck table 42. The carry-out means 36 is configured by providing a carry-out pad 38 at the tip of a carry-out arm 37 that can turn on the base 11. In the unloading means 36, the wafer W is lifted from the chuck table 42 by the unloading pad 38, and the unloading pad 38 is turned by the unloading arm 37, whereby the wafer W is unloaded from the chuck table 42.

  The cleaning mechanism 26 is configured by providing various nozzles (not shown) that inject cleaning water and dry air toward a spinner table (chuck table) 27. In the cleaning mechanism 26, the spinner table 27 holding the wafer W is lowered into the base 11, cleaning water is sprayed in the base 11 and the wafer W is spinner cleaned, and then dry air is blown to blow the wafer W. Is dried. Behind the carry-in means 31 and the carry-out means 36 is provided a turntable 41 in which four chuck tables 42 are rotatably arranged at equal intervals in the circumferential direction. A holding surface 43 for holding the wafer W is formed on the upper surface of each chuck table 42.

  When the turntable 41 is intermittently rotated at intervals of 90 degrees, the loading / unloading position where the wafer W is loaded and unloaded, the rough grinding position facing the rough grinding means 46, the finish grinding position facing the finish grinding means 51, and the polishing means The polishing position facing 56 is sequentially positioned. At the rough grinding position, the wafer W is roughly ground to a predetermined thickness by the rough grinding means 46. At the finish grinding position, the finish grinding means 51 finish-grinds the wafer W to the finish thickness. At the polishing position, the wafer W is polished by the polishing means 56. Around the turntable 41, columns 12, 13, and 14 are erected.

  The column 12 is provided with a drive mechanism 61 that moves the rough grinding means 46 up and down. The drive mechanism 61 includes a pair of guide rails 62 arranged in front of the column 12 and parallel to the Z-axis direction, and a motor-driven Z-axis slider 63 slidably installed on the pair of guide rails 62. Yes. A rough grinding means 46 is supported on the front surface of the Z-axis slider 63 via a housing 64. A ball screw 65 is screwed onto the back side of the Z-axis slider 63, and a drive motor 66 is connected to one end of the ball screw 65. The ball screw 65 is rotationally driven by the drive motor 66, and the rough grinding means 46 is moved along the guide rail 62 in the Z-axis direction.

  Similarly, the column 13 is provided with a drive mechanism 71 for moving the finish grinding means 51 up and down. The drive mechanism 71 includes a pair of guide rails 72 arranged in front of the column 13 and parallel to the Z-axis direction, and a motor-driven Z-axis slider 73 slidably installed on the pair of guide rails 72. Yes. A finish grinding means 51 is supported on the front surface of the Z-axis slider 73 via a housing 74. A ball screw 75 is screwed to the back side of the Z-axis slider 73, and a drive motor 76 is connected to one end of the ball screw 75. The ball screw 75 is rotationally driven by the drive motor 76, and the finish grinding means 51 is moved along the guide rail 72 in the Z-axis direction.

  A mount 48 is provided at the lower end of the spindle 47 of the rough grinding means 46, and a rough grinding wheel 49 in which a plurality of rough grinding wheels 50 are annularly arranged is mounted on the lower surface of the mount 48. The rough grinding wheel 50 is composed of, for example, a diamond grinding stone in which diamond abrasive grains are hardened with a binder such as a metal bond or a resin bond. Further, a mount 53 is provided at the lower end of the spindle 52 of the finish grinding means 51, and a finish grinding grinding wheel 54 in which a plurality of finish grinding wheels 55 are annularly arranged is mounted on the lower surface of the mount 53. The finish grinding wheel 55 is composed of abrasive grains having a smaller particle diameter than the coarse grinding wheel 50.

  The column 14 is provided with a drive mechanism 81 for positioning the polishing means 56 at a predetermined polishing position with respect to the wafer W. The drive mechanism 81 includes a pair of guide rails 82 arranged in front of the column 14 and parallel to the Y-axis direction, and a motor-driven Y-axis slider 83 slidably installed on the pair of guide rails 82. Yes. The drive mechanism 81 includes a pair of guide rails 84 arranged in front of the Y-axis slider 83 and parallel to the Z-axis direction, and a motor-driven Z-axis slider 85 slidably installed on the pair of guide rails 84. have. A polishing means 56 is supported on the front surface of the Z-axis slider 85 via a housing 86.

  A ball screw (not shown) is screwed to the back side of the Y-axis slider 83 and the Z-axis slider 85, and drive motors 87 and 88 are connected to one end of the ball screw. The ball screw is rotationally driven by the drive motors 87 and 88, and the polishing means 56 is moved along the guide rails 82 and 84 in the Y-axis direction and the Z-axis direction. A mount 94 is provided at the lower end of the spindle 93 of the polishing means 56, and a polishing pad 95 made of foam or fiber is attached to the lower surface of the mount 94. By grinding the wafer W with the polishing pad 95, the grinding damage left on the wafer W is removed.

  In such a grinding and polishing apparatus 1, the wafer W is transferred from the cassette CT to the positioning mechanism 21, and the wafer W is centered by the positioning mechanism 21. Next, the wafer W is loaded onto the chuck table 42, and the wafer W is positioned in the order of the rough grinding position, the finish grinding position, and the polishing position by the rotation of the turntable 41. The back surface of the wafer W is roughly ground at the rough grinding position, and the back surface of the wafer W is finish ground at the finish grinding position, and the wafer W is thinned to a predetermined finish thickness by these grinding operations. As a result of this thinning, a cutting groove by the front dicing method appears on the back surface of the wafer W, and the wafer W is divided into individual semiconductor chips C to become individual wafers Wa (see FIG. 2). After the rough grinding process and the finish grinding process, the individual wafer Wa is polished at the polishing position. Then, after the singulated wafer Wa is transferred from the chuck table 42 to the spinner table 27, the singulated wafer Wa is cleaned by the cleaning mechanism 26 and is cleaned into the cassette CT from the cleaning mechanism 26. Wafer Wa is unloaded.

  Next, the chuck table mechanism and the transport pad of the present embodiment will be described with reference to FIG. FIG. 2 is a schematic configuration diagram of the chuck table mechanism and the transport pad. As shown in FIG. 2, the chuck table mechanism 100 according to the present embodiment includes the chuck table 42 described above. The chuck table mechanism 100 includes four chuck tables 42 (see FIG. 1). Since each chuck table 42 has the same configuration, one chuck table 42 is illustrated and described. The chuck table 42 includes a porous member 42a that forms an upper surface of the chuck table 42. The porous member 42a is made of porous ceramics having numerous suction holes. The porous member 42 a forms a holding surface 43 for sucking and holding the wafer W on the upper surface of the chuck table 42. The chuck table 42 is formed with a communication path 42 b that communicates with the holding surface 43.

  In the chuck table mechanism 100 of the present embodiment, a suction source 102 is communicated with the communication path 42b via the suction path 101. An electromagnetic on-off valve 105 is disposed in the vicinity of the suction source 102 of the suction passage 101. When the electromagnetic on-off valve 105 is opened, the suction source 102 communicates with the holding surface 43 via the suction passage 101 and the communication passage 42b. A suction force is applied to the protective tape T that abuts against 43.

  In the suction passage 101, pressure detecting means 107 is disposed in the vicinity of the communication passage 42b, and the pressure detecting means 107 detects the pressure in the suction passage 101. A release path 108 is provided by branching between the pressure detection means 107 of the suction passage 101 and the suction source 102. A control valve 109 is provided in the release path 108, and the release path 108 is released to the atmosphere by adjusting the valve opening degree of the control valve 109 and opening the valve from the closed state. Then, the suction passage 101 and the communication passage 42b, which become negative pressure by the air release, can be increased in pressure.

  Further, the chuck table mechanism 100 according to the present embodiment includes a control unit 111 that controls the electromagnetic on-off valve 105 and the control valve 109 based on a detection signal from the pressure detection unit 107. The control unit 111 includes a processor that executes various processes, a memory, and the like. The memory is composed of one or a plurality of storage media such as a ROM (Read Only Memory) and a RAM (Random Access Memory) depending on the application. Although not described here, the suction source 102 is communicated with each of the four chuck tables 42 through valves and passages in the same manner as described above, and suction on the holding surface 43 is controlled by control by the control means 111. The

  On the holding surface 43 of the chuck table 42, the wafer W is sucked and held via the protective tape T. The transfer (carrying out) of the wafer W from the holding surface 43 of the chuck table 42 is performed by the transfer pad 33. A suction holding surface 33 a is formed on the lower surface of the transfer pad 33, and the suction holding surface 33 a is formed to have a diameter corresponding to the outer diameter of the wafer W. A communication path (not shown) communicating with the suction holding surface 33a is formed in the transport pad 33, and a suction source 33c is communicated with the communication path via a suction path 33b. The suction passage 33b is provided with a transport pad electromagnetic valve 33d. When the wafer W is transferred from the holding surface 43 of the chuck table 42, the suction holding surface 33 a of the transfer pad 33 is brought into contact with the upper surface (back surface) of the wafer W. In this abutted state, it operates to open the transfer pad electromagnetic valve 33d, and the suction source 33c communicates with the suction holding surface 33a, whereby the singulated wafer Wa is sucked and held by the suction holding surface 33a. .

  By the way, the protective tape T is adhered to the wafer W before grinding, and in the wafer W having the convex portion B, the protective tape T is adhered along the unevenness of the surface of the wafer W formed by the convex portion B. Is done. Accordingly, the protective tape T attached to the surface of the wafer W is also formed in a concavo-convex shape so as to protrude at the position where the convex portion B is formed. When the back surface of the wafer W is ground and polished, the holding surface 43 of the chuck table 42 is sucked and held with the protective tape T side facing downward. Here, the suction source 102 used for suction is connected to a large suction pump that supplies negative pressure to a plurality of various devices in a factory or facility. Since the negative pressure by this suction pump has various utilization modes, it is set so as to exhibit a relatively high suction force.

  For this reason, in the suction holding of the conventional chuck table mechanism, as shown in FIG. 3B, when the protective tape T is sucked and held by the holding surface 43, the protective tape T comes into surface contact with the holding surface 43 as a whole. It becomes flat. As a result, the protective tape T is peeled from the surface of the wafer W between the adjacent convex portions B, and bubbles A are generated in the peeled portion.

  Therefore, in the present embodiment, while the wafer W can be held on the chuck table 42 so as not to move during processing, a suction pressure at which bubbles A are not generated as shown in FIG. The wafer W is held in accordance with the suction pressure as described below. Thereby, generation | occurrence | production of the bubble A mentioned above can be prevented, making the suction | attraction force added to the wafer W from the chuck table 42 sufficient.

  Hereinafter, with reference to FIG. 3 in addition to FIG. 2, the flow of holding the wafer W of the present embodiment by the chuck table 42 will be described. 2 and 3 are explanatory diagrams of each step in the holding method of the present embodiment. FIG. 2 is an explanatory diagram of the placing step, and FIG. 3 is an explanatory diagram of the control valve adjusting step. Note that the steps shown in FIGS. 2 and 3 are merely examples, and the present invention is not limited to this configuration.

  As shown in FIG. 2, a mounting step is first performed. In the mounting step, the wafer W is brought into contact with the suction holding surface 33a of the transfer pad 33, the transfer pad electromagnetic valve 33d is opened, and the suction source 33c is communicated with the suction holding surface 33a. As a result, a suction force is applied to the wafer W in contact with the suction holding surface 33a, and the wafer W is sucked and held by the suction holding surface 33a. In this state, the transfer pad 33 is moved, and the protective tape T attached to the wafer W is brought into contact with the holding surface 43 of the chuck table 42. Then, with the control valve 109 closed, the electromagnetic on-off valve 105 is opened, and the holding surface 43 and the suction source 102 communicate with each other, and the protective tape T that contacts the holding surface 43 is sucked and held.

  As shown in FIG. 3, the control valve adjustment step is performed after the placement step. In the control valve adjustment step, the control valve 109 closed from the state shown in FIG. 2 is opened to release the release path 108 to the atmosphere. As a result of this release, external air flows from the control valve 109 into the suction passage 101 through the release passage 108 to weaken the negative pressure in the suction passage 101 and the communication passage 42b, and the protective tape T adhered to the wafer W is sucked and held. Reduce suction power. At this time, the pressure detection means 107 detects the pressure value in the suction passage 101 and outputs it to the control means 111 as a detection signal. The control unit 111 controls the valve opening degree of the control valve 109 based on the detection signal output from the pressure detection unit 107. Specifically, in the control unit 111, the pressure value in the suction passage 101 detected by the pressure detection unit 107 is compared with a predetermined threshold value. If the detected pressure value is larger than the threshold value, that is, if the negative pressure becomes weak, the control is performed. Control is performed to reduce the valve opening of the valve 109. On the other hand, when the detected pressure value is smaller than the threshold value, that is, when the negative pressure becomes strong, control is performed to increase the valve opening degree of the control valve 109. As a result, the protective tape T attached to the wafer W with a predetermined pressure corresponding to the threshold is sucked and held on the chuck table 42.

  The above-mentioned threshold value is maintained so that the wafer W does not move with respect to the chuck table 42 during grinding or polishing, and the uneven shape of the protective tape T is maintained without generating bubbles A as shown in FIG. 3B. Thus, the suction pressure can be sucked and held. The threshold value is not particularly limited, but can be obtained in advance by performing experiments and tests according to the various wafers W and the protective tape T held by the chuck table 42. The threshold value for the wafer W and the protective tape T to be held may be a predetermined value having no range, but is preferably a predetermined numerical range having an upper limit value and a lower limit value.

  As described above, in the holding using the chuck table mechanism 100 of the present embodiment, the valve opening degree of the control valve 109 is adjusted according to the pressure value detected by the pressure detecting means 107, and suction by the chuck table 42 is performed. The pressure can be made variable. As a result, even if the negative pressure at the suction source 102 is increased due to facility reasons, the negative pressure at the chuck table 42 can be moderately reduced, and the protective tape T along the unevenness as shown in FIG. It is possible to prevent bubbles A from being generated between the wafer W and the protective tape T by being deformed flat. Therefore, it is possible to avoid contamination due to the processing waste such as contamination generated by grinding entering the bubbles A.

  Moreover, although the negative pressure at the chuck table 42 is weakened by releasing the atmosphere by the control valve 109, the negative pressure does not become too weak by controlling the valve opening of the control valve 109. Thereby, even if an external force is applied to the wafer W during grinding or polishing, the wafer W is prevented from being displaced due to suction holding by the chuck table 42 only at the portion protruding according to the convex portion B on the protective tape T. can do.

  The embodiments of the present invention are not limited to the above-described embodiments, and various changes, substitutions, and modifications may be made without departing from the spirit of the technical idea of the present invention. Furthermore, if the technical idea of the present invention can be realized in another way by technological advancement or another derived technique, the method may be used. Accordingly, the claims cover all embodiments that can be included within the scope of the technical idea of the present invention.

  For example, the chuck table constituting the chuck table mechanism 100 is not limited to the chuck table 42 that sucks and holds the wafer W to be processed when grinding or polishing, but is changed to the spinner table 27 or the like of the cleaning mechanism 26. May be. In this case, the spinner table 27 is configured in the same manner as the chuck table 42 shown in FIG. 2, and the cleaned wafer W is transferred to a transfer device or the like by a transfer pad.

  Further, the control of the valve opening degree by the control valve 109 may be continued for the control valve 109 or may be intermittently opened and closed a plurality of times.

  Moreover, it is good also as a thing which abbreviate | omitted at least one of formation of the convex part B and sticking of the protective tape T as a plate-shaped object. In this case, for example, when the plate-like material is a soft material or a brittle material, the pressure for sucking and holding is appropriately adjusted by controlling the valve opening degree of the control valve 109, and the stress generated in the plate-like material is adjusted. It is possible to reduce deformation and suppress deformation.

  As described above, the present invention has an effect that air bubbles can be prevented from being generated between the protective tape and a pressure acting on the wafer while holding the wafer satisfactorily. This is useful for a chuck table mechanism that sucks and holds a wafer formed and attached with a protective tape.

42 Chuck table 42b Communication path 43 Holding surface 100 Chuck table mechanism 101 Suction path 102 Suction source 105 Electromagnetic on-off valve 107 Pressure detection means 108 Release path 109 Control valve 111 Control means T Protection tape W Wafer (plate member, semiconductor wafer)

Claims (1)

In a chuck table mechanism comprising: a holding surface for sucking and holding a plate-like object; a chuck table including a communication path communicating with the holding surface; and a suction source connected to the communication path via a suction path.
Pressure detecting means disposed in the suction passage in the vicinity of the communication passage for detecting the pressure in the suction passage;
A release path branched between the pressure detection means of the suction passage and the suction source and released to the atmosphere via a control valve;
Control means for controlling the valve opening of the control valve based on a detection signal from the pressure detection means,
The control means controls the valve opening degree of the control valve so as to suck and hold at a predetermined pressure corresponding to the plate-like object.

Images