JP4895671B2 - Processing equipment - Google Patents

Description

  The present invention relates to a processing apparatus for thinning a semiconductor wafer, and more particularly to an apparatus for adhering a dicing tape to the back surface of a semiconductor wafer while being fixed to a suction table after the thinning process.

  A semiconductor wafer (hereinafter abbreviated as “wafer”) having a plurality of semiconductor devices formed on the surface is attached to a dicing tape after a thinning process for finishing to a required thickness by a back grinding process or the like, and is individually applied by a dicing apparatus Divided into semiconductor chips. At this time, the thinned wafer is transferred to a sticking apparatus for sticking a dicing tape by being stored in a cassette or the like or sucked and fixed to a transfer pad, and is fixed to a suction table there and then dicing. Tape is applied. About this sticking apparatus, it describes in patent document 1, for example. Further, there is known a system in which a processing apparatus for thinning a wafer and a dicing tape sticking apparatus are arranged adjacent to each other and a thinning process and a dicing tape sticking process are continuously performed.

JP2003-152058

  By the way, in the above-described technique, it is necessary to once remove the wafer that has been sucked and held in the thinning process from the suction table and store it in a cassette or transport it to a sticking device using a transport pad. At this time, it is necessary to release the vacuum suction, but stress may be applied to the thinned wafer at this time to break the wafer. In particular, when the thickness is 50 μm or less, such a tendency becomes remarkable. In addition, the system that continuously performs the thinning process and the dicing tape attaching process places two devices adjacent to each other, which increases the space required for installing the device and increases the wafer processing cost. There is a problem. Therefore, an object of the present invention is to provide a technique capable of preventing damage to the wafer that occurs after the wafer thinning process and reducing the processing cost of the wafer.

The processing apparatus of the present invention is a processing apparatus for thinning a semiconductor wafer , and is arranged on the apparatus base so as to be rotatable and on the index table along the rotation direction of the index table. by a plurality of suction table for sucking fixing the wafer in a direction in which expose the back surface, around said index table on the device base, disposed along the rotational direction of the index table, the suction table A plurality of means for sequentially performing a predetermined process on the wafer fixed to the suction table, the means positioning the wafer at a transfer start position to the suction table; and from the positioning stage A transfer arm that moves the wafer to the suction table in a direction to expose the back surface thereof; Grinding means for grinding and thinning the back surface of c, a polishing wheel for polishing the back surface of the wafer ground by the grinding means, a cleaning pad for cleaning the wafer polished by the polishing wheel, Adhering means for adhering an adhesive film for bonding to the back side of the wafer cleaned with the cleaning pad, and rigidity on the periphery on the back side of the wafer to which the adhesive film adhering means for bonding is adhered. And a wafer mounting means for pressing and adhering the dicing tape having the dicing frame attached thereto to the back surface of the wafer by an elastic member protruding from the center .

In the processing apparatus of the present invention, when the index table rotates, the suction table sequentially moves to the positions of the positioning stage, the transfer arm, the grinding means, the polishing wheel, the cleaning pad, the attaching means, and the wafer mounting means, and after the grinding means This process is performed on the wafer that is suction-fixed on the suction table. In other words, the wafer is transferred onto one suction table among the plurality of suction tables on the index table by the transfer arm, fixed by suction, and held by suction on the suction table. A series of processes such as thinning, back surface polishing, cleaning, adhering a bonding adhesive film to the back surface, and adhering a dicing tape to the back surface are sequentially performed. During a series of processes from grinding to dicing tape sticking, it is not necessary to release the thinned wafer from the suction table and transport it thereafter. Therefore, it is possible to prevent the thinned wafer from being damaged in the previous stage of the attaching process to the dicing tape. And, the transportation of the wafers when removing the wafer from the adsorption table, the wafer has been stuck to the dicing tape is performed by supporting the dicing frame. Since the dicing frame is rigid and the dicing tape supports the wafer on its surface, stress that may cause breakage is applied to the wafer when the wafer is released from the suction state and then transferred. Absent. For this reason, damage to the wafer can be prevented.

  In addition, the processing device of the present invention has a structure in which a plurality of suction tables are arranged on the index table, and each operation is sequentially performed by rotating the index table. Therefore, the processing device is compared with a structure in which two different devices are arranged side by side. And it can be made small. For this reason, the installation space in a factory can be made small and the processing cost of a wafer can be reduced.

  As processing means for thinning the wafer, grinding, a combination of grinding and polishing, chemical etching (wet etching or plasma etching), chemical mechanical polishing, or a combination of these can be used. Of these, grinding or a combination of grinding and polishing is advantageous in terms of work efficiency and cost.

  The wafer mounting means is a device for adhering a dicing tape having a ring-shaped and rigid dicing frame attached to the peripheral edge to a wafer that is adsorbed and held on an adsorption table, and the dicing tape is attached to one side. It has adhesiveness.

In the processing apparatus of the present invention, an adhesive film for bonding (such as a die attach film (DAF)) is attached to the back surface of the wafer while being fixed to the suction table by the attaching means . Thereby , in a state where the wafer is adsorbed on the adsorption table, an adhesive resin for adhering the separated semiconductor chip to the substrate or laminating the wafer can be adhered to the back surface of the wafer. . Also in this case, after the wafer is thinned, the bonding adhesive film can be attached without releasing the vacuum suction state, so that the wafer can be prevented from being damaged.

In the processing apparatus of the present invention, by a central included in the wafer mounting means presses the dicing tape to the wafer rear surface by an elastic member which projects, dicing tape dicing frame is adhered is adhered to the back side of the wafer . According to this , when the dicing tape is pressed against the back surface of the wafer by the elastic member protruding from the center, the pressing starts from the center of the back surface of the wafer, and the elastic member is crushed and deformed as the pressing proceeds. Then, a dicing tape is attached from the center of the wafer toward the periphery. Thereby, air can be prevented from entering between the wafer and the dicing tape. If air bubbles are present between the wafer and the dicing tape, an accident such as scattering of the cut chips occurs in the subsequent dicing process. Therefore, it is important that no bubbles remain between the wafer and the dicing tape. This method has a simple mechanism and high operational reliability. Further, since the pressing is performed by the deformation of the elastic member, it is possible to prevent the occurrence of an accident such as breakage of the wafer even if the operation of the apparatus is defective.

  Examples of the elastic member protruding from the center include a balloon-like thin skin elastic member which expands due to gas pressure, and a member obtained by forming a sponge-like material into a round dome-shaped convex shape. The method using a balloon-like elastic member has an advantage that the state of pressing can be finely adjusted by controlling the pressure of the expanding gas.

  According to the present invention, the wafer thinning process and the subsequent dicing tape attaching process to the wafer are performed in a state where the wafer is adsorbed to the adsorption table. The wafer after being attached to the dicing tape is supported on the surface by the dicing tape, and the transfer is performed by supporting the dicing frame. Therefore, when removing the wafer from the suction table, the wafer is further damaged in the subsequent transfer state. Such stress can be prevented from being applied to the wafer. For this reason, damage to the wafer that occurs after the wafer thinning step can be prevented. Further, since the plurality of suction tables are arranged on the rotatable index table, the processing apparatus can be reduced in size. For this reason, the area occupied by the apparatus in the factory can be reduced, and the wafer processing cost can be reduced.

(Thinned wafer)
FIG. 1 is a view showing a wafer to be thinned. As shown in FIG. 1, a semiconductor chip region 1a having a semiconductor integrated circuit device is formed on the surface of a wafer 1, and a notch 1b used for positioning is formed at one location around the semiconductor chip region 1a. Moreover, the protective tape 2 is stuck on the surface. In the following description, the surface on which the semiconductor chip region 1a of the wafer 1 is formed is referred to as the front side, and the back side thereof is expressed as the back side.

(Configuration of processing equipment)
FIG. 2 is a perspective view showing a wafer processing apparatus using the present invention. FIG. 3 is a plan view of the processing apparatus shown in FIG. The processing apparatus 10 has a configuration in which various processing axes for a wafer, a transfer system, and the like are disposed on a rectangular apparatus base 10a. A wafer 1 shown in FIG. 1 is horizontally arranged on a wafer carrier 11 with the surface facing up, and a plurality of wafers 1 are vertically arranged and stored. There are two wafer carriers 11, each mounted on a wafer carrier stage 12. The wafer 1 in the wafer carrier 11 is pulled out by the multi-joint robot 13 for wafer transfer and transferred to the positioning stage 20.

  The articulated robot 13 is fixed on the robot base 14. The robot base 14 is arranged on the linear guide 15 and is movable in the X direction by a ball screw feed mechanism 17 driven by a drive motor 16. The articulated robot 13 includes a pad 13a having a vacuum suction mechanism and a four-axis articulated mechanism 13b. The multi-joint mechanism 13b can be moved up and down by a mechanism (not shown). The pad 13a moves freely in the XY plane by the multi-joint mechanism 13b. The pad 13a is provided with a mechanism that can be turned upside down by 180 ° with the wafer adsorbed and fixed thereon.

  When pulling out the wafer 1 from the wafer carrier 11, the robot base 14 moves in the X-axis direction to face one wafer carrier 11, and then the articulated mechanism 13b moves up and down to raise the height of the wafer 1 to be transferred. The height of the pad 13a is adjusted so as to match, and the multi-joint mechanism 13b is extended to insert the pad 13a under the wafer 1. Then, the pad 13a is lifted up slightly, the back surface side of the wafer 1 is sucked and held by the vacuum suction mechanism, and then the multi-joint mechanism 13b is contracted to pull out the wafer 1 from the wafer carrier 11. At this time, the front and back of the wafer 1 pulled out from the wafer carrier 11 is reversed at an appropriate timing by the above-described vertical flipping mechanism of the pad 13a.

  The wafer 1 whose front and back are reversed while being sucked and fixed to the pad 13a is transported on a positioning stage 20 described below with the back side up. At this time, the multi-joint mechanism 13b is rotated, and the multi-joint mechanism 13b is extended, whereby the wafer 1 is transferred to the positioning stage 20.

  The positioning stage 20 includes a table 20 a having a vacuum suction function and a rotation function, and a plurality of positioning pins 22 arranged near the outer edge of the wafer 1. The rotation of the table 20a is controlled by an AC servo motor with an encoder so that the position of the notch 1b (see FIG. 1) of the wafer 1 can be stopped at a predetermined angular position. The positioning pins 22 are simultaneously driven toward the center of the wafer 1 and operate so that the rotation center of the table and the center of the wafer are always aligned at a fixed position. Further, the positioning stage 20 includes a notch sensor 21 using a light projecting / receiving sensor. The notch sensor 21 detects the position of the notch 1b on the wafer. The position of the notch 1b is detected by the notch sensor 21 by rotating the table 20a of the positioning stage 20, and the wafer is further rotated with reference to the position of the notch 1b, so that the notch 1b of the wafer fixed on the chuck table 40 can be detected. Positioning is performed.

  The wafer that has been positioned on the positioning stage 20 is transported to the chuck table 40 with the back side up by a transport arm 31 having a transport pad 30 having a vacuum suction function at its tip. The transport pad 30 has a vacuum suction function, and the transport arm 31 can be swung up and down by a mechanism (not shown). The chuck table 40 has a rotation function and a vacuum suction function, and seven chuck tables 40 are arranged on the index table 41 so as to be at equal angular positions. The rotation of the chuck table 40 is controlled by an AC servo motor with an encoder. Thus, the position of the notch 1b of the wafer 1 fixed on the chuck table 40 is always set to a constant angular position after the rotation. The index table 41 is rotatable on the apparatus base 10a. With this function, as shown in FIG. 3, the wafer first sucked and fixed on the chuck table 40 at the position A with the back side facing up is rotated next by the chuck table 40 rotating clockwise. Then, it receives a predetermined machining, then moves to a position C, receives the next machining, and further sequentially moves in the order of D → E → F → G to sequentially receive the predetermined machining and processing.

3A, the wafer fixed to the chuck table 40 is positioned under the first processing unit (grinding means) 50 shown in B by the rotation of the index table 41 in the clockwise direction. The first processing unit 50 is a grinding processing unit that performs rough grinding, and includes a column 58 disposed on the apparatus base 10 a and a spindle 51 that moves up and down in the Z direction with respect to the column 58. The spindle 51 is fixed to the first machining axis base 55, and the first machining axis base 55 is supported by the linear guide 56 in a state where it can move in the Z direction. The first machining shaft base 55 is engaged with a first machining shaft drive mechanism 57 having a ball screw feed mechanism (not shown), and the spindle 51 can move up and down by its action.

  FIG. 4 is an enlarged perspective view (A) and side view (B) of the spindle 51 portion. A spindle motor 52 is disposed above the spindle 51. The spindle motor 52 rotates the rotating shaft 51a of the spindle 51. A flange 53 is fixed to the lower end of the rotating shaft 51 a, and a cup wheel 54 that is a processing tool is fixed to the flange 53. A plurality of grindstones 59 having an abrasive grain size of about # 320 to 600 are fixed to the annular portion on the edge of the lower surface of the cup wheel 54. The cup wheel 54 is provided with a grinding water supply port (not shown) for supplying grinding water for cooling and lubrication of the grinding surface or discharging grinding scraps. The first processing unit 50 is provided with a water supply line (not shown) for supplying grinding water to the grinding water supply port.

  Reference numeral 60 in FIG. 4 is a height gauge that detects the position of the surface of the wafer 1. The height gauge 60 detects the position (position in the height direction) of the surface of the wafer 1 when the tip of the probe 61 contacts the surface of the wafer 1. Further, a height gauge 62 is disposed adjacent to the height gauge 60, and the tip of the probe 63 contacts the surface of the chuck table 40, and the position of the surface of the chuck table 40 is detected. Then, the outputs of the height gauges 60 and 62 are compared, and the thickness of the wafer 1 is measured in real time.

  In the grinding process, the chuck table 40 rotates at 100 to 300 rpm while the wafer 1 is fixed on the chuck table 40. Grinding is performed by pressing the cup wheel 54 that rotates in the same direction at 2000 to 5000 rpm to the back surface of the wafer 1 to be exposed. At this time, the spindle 51 is lowered by the function of the first machining axis drive mechanism 57 shown in FIG. 2 to feed the machining axis, and the cup wheel 54 is pressed against the back surface of the wafer 1. The thickness of the wafer 1 during and before processing is monitored in real time by the height gauges 60 and 62, and in-process control is performed to stop feeding the processing axis when the wafer 1 reaches a preset thickness. Note that the rotation direction of the chuck table 40 and the rotation method of the cup wheel 54 may be reversed.

The wafer that has been ground in the first processing unit 50 remains adsorbed by the chuck table 40, and the position of the second processing unit 70 (grinding means) (as shown in FIG. Position). The second processing unit 70 has the same basic structure as the first processing unit 50. In the second machining unit 70, a spindle 71 is fixed to a column 78 in a state of being vertically movable by a second machining axis drive mechanism 77, and a cup wheel 74 that is rotationally driven by a spindle motor 72 is provided below the spindle 71. I have. The second processing unit 70 is different from the first processing unit 50 in the abrasive grain size of the grindstone attached to the cup wheel 74. In this example, the abrasive grain size of the grindstone by the second machining unit 70 is set to about # 2000 to # 8000, and finish grinding after the rough grinding performed in the first machining unit 50 is performed in the second machining unit 70. Yes.

  The wafer that has been ground by the second processing unit is moved to the position of the third processing unit 80 (the position of D in FIG. 3) by the rotation of the index table 41 in a state where it is attracted to the chuck table 40. . The third processing unit 80 has the same basic structure as the first processing unit 50. In the third machining unit 80, a spindle 81 is fixed to a column 88 in a state where it can be moved up and down by a third machining axis drive mechanism 87, and a polishing wheel 84 that is rotationally driven by a spindle motor 82 is below the spindle 81. It is attached. A felt grindstone is fixed to the lower surface of the polishing wheel 84. Polishing of the back surface side of the wafer 1 is performed by rotating the polishing wheel 84 and the chuck table in the same direction or in the reverse direction in a state where the felt grindstone on the lower surface of the polishing wheel 84 is pressed against the back surface of the wafer 1. This felt grindstone is obtained by dispersing a grindstone in a felt and hardening it with an adhesive. As the felt material, synthetic fibers such as polyester and nylon, and natural fibers such as wool, cotton, and hemp are used, and are formed to have an appropriate hardness and density. The abrasive grains dispersed in the felt are made of silica, alumina, diamond or the like, and the particle diameter is, for example, about 0.01 to 100 μm. The felt grindstone is described in detail in Japanese Patent Application Laid-Open Nos. 2000-283243 and 2003-188118 in which the applicant's invention is described.

  The third processing unit 80 performs dry polishing on the back surface of the wafer, and removes the mechanical damage layer generated by grinding. Thereby, the strength of the wafer after grinding is improved.

  The wafer that has been dry-polished by the third processing unit 80 is moved to the position indicated by E in FIG. 3 by the clockwise rotation of the index table 41 in a state where the wafer is sucked and fixed to the chuck table 40. . Then, at the position indicated by E in FIG. 3, the surface on which the wafer has been ground and polished is cleaned. A wafer cleaning pad 90 for performing this cleaning is disposed in the vicinity of E shown in FIG. The wafer cleaning pad 90 is a flat disk-shaped urethane resin or an appropriate unevenness formed on its cleaning surface. The wafer cleaning pad 90 may be one in which a nylon brush is implanted in a direction perpendicular to the wafer back surface on a cleaning surface of a resin disk.

  The wafer cleaning pad 90 is attached to the tip of the wafer cleaning arm 91 in a rotatable state. A rotation motor 92 for rotating the wafer cleaning pad 90 is disposed at the tip of the wafer cleaning arm 91, and the wafer cleaning pad 90 is rotated by the rotation motor 92. The wafer cleaning arm 91 is pivotable, and the wafer cleaning pad 90 can be properly retracted from the wafer at the position E in FIG. The wafer cleaning arm 91 includes a vertical movement mechanism (not shown) for pressing the wafer cleaning pad 90 against the wafer, and a cleaning water supply mechanism (not shown) for supplying cleaning water to the wafer cleaning pad 90. Yes. The supply of the cleaning water may be performed on the wafer cleaning pad 90 or on the exposed surface of the wafer by a nozzle disposed at a position adjacent to the wafer cleaning arm 91.

  The wafer that has been cleaned is moved to the position indicated by F in FIG. 3 by the clockwise rotation of the index table 41 in a state where the wafer is attracted and fixed to the chuck table 40. In the position shown by F in FIG. 3, an adhesive film for bonding is attached to the back surface of the wafer. This bonding adhesive film is an adhesive means for bonding a cut and separated semiconductor chip (divided for each semiconductor chip region 1a shown in FIG. 1) to a substrate. Also called a bonding sheet. When a dicing tape in which the bonding adhesive film is integrated is used, the bonding adhesive film is not attached to the wafer at the position F in FIG.

The bonding adhesive film is a film having a thickness of about 10 to 50 μm made of a thermosetting or thermoplastic resin such as epoxy or polyimide, and is a long film that has been previously punched into the same size as the wafer and has a releasing function. Attached to the base plate sheet 106. The base sheet 106 is wound around the feed roller 102 and pulled out by the guide roller 103. The drawn base sheet 106 is pressed onto the back surface of the wafer at the position F in FIG. 3 by an attaching roller (attaching means) 101 and attached to the base sheet 106. Is attached to the back side of the wafer. The adhering roller 101 moves while rotating from end to end of the wafer toward the center of the index table 41 while pressing the wafer. Thereby, the bonding adhesive film is pressed against and adhered to the wafer. After the bonding adhesive film is attached to the wafer, the base sheet 106 is taken up by the take-up roller 104 through the guide roller 105.

  The affixing roller 101, the feed roller 102, the guide roller 103, the take-up roller 104, and the guide roller 105 are supported by a roller base 100 shown in FIG. The roller base 100 includes a rotation mechanism (not shown) for rotating the take-up roller 104, and also includes a mechanism (not shown) for moving the attaching roller 101 while rotating the pressing roller 101 against the wafer.

  When a release paper is attached to the surface opposite to the base sheet 106 of the bonding adhesive film (not shown), the release paper is wound up and attached by a separator roller (not shown) while the base sheet 106 is fed out. Adhesion is performed with the surface exposed and facing the back of the wafer. Further, a heating mechanism such as a heater is embedded in the sticking roller 101, and sticking to the back surface of the wafer is performed while heating the bonding adhesive film attached to the base sheet 106 as necessary. be able to.

  After bonding of the bonding adhesive film in F of FIG. 3 is performed, the wafer 1 is rotated to the position of G of FIG. Moved to the indicated position. At the position shown in FIG. 3G, the dicing tape is attached to the wafer 1, and then the wafer 1 in the state attached to the dicing tape is removed from the chuck table 40 together with the dicing frame. Be transported.

That is, a frame mount unit (wafer mounting means) 111 for adhering a dicing tape to a wafer that is sucked and fixed on the chuck table 40 is disposed above the position G in FIG. The frame mount unit 111 is supported by a frame mount base 110 fixed to the apparatus base 10a. The frame mount base 110 is moved up and down with respect to the apparatus base 10a by a vertical movement drive mechanism (not shown) so that the height position of the lower end surface of the frame mount base 110 can be adjusted.

  FIG. 5 is a top view (A) and a sectional view (B) showing a dicing tape frame. As shown in FIG. 5, the dicing tape frame 5 is configured by sticking a substantially ring-shaped frame 3 to the periphery of a circular dicing tape 4. The dicing tape 4 is a film-like resin material in which an adhesive is applied to the lower surface shown in FIG. The dicing tape 4 is fixed to the dicing frame 3 by the adhesiveness of the adhesive. Further, due to this adhesiveness, the dicing tape 4 is adhered to the wafer 1 and the wafer 1 is supported by the surface. Since the dicing tape 4 is adhered to the dicing frame 3, the wafer 1 in a state of being adhered to the dicing tape 4 is transported by grasping the dicing frame 3 with a clamp mechanism.

  FIG. 6 is an operation diagram showing an outline of the operation of the frame mount unit. 6A, the chuck table 40 is in the position indicated by G in FIG. 3, and a gap is formed above the wafer 1 that is sucked and fixed thereon with the protective tape 2 down (front side down). A state in which the dicing tape frame 5 is positioned and the frame mount unit 111 is positioned above the dicing tape frame 5 is shown. In FIG. 6, the bonding adhesive film attached at the position indicated by F in FIG. 3 is not shown.

  The frame mount unit 111 has a cylindrical shape whose inner diameter is larger than that of the wafer 1. The opening on the bottom surface of the frame mount unit 111 is closed by a film-like elastic member 112. The elastic member 112 is made of a sheet material such as rubber and has a thickness of about 0.1 mm to 5 mm, and an optimum thickness is selected according to the material properties. A restraining plate 113 is provided inside the elastic member 112 with a gap therebetween. An air supply pipe 114 is provided at the center of the restraining plate 113 so that pressure gas can be injected into the gap between the elastic member 112 and the restraining plate 113. When high-pressure gas is injected from the supply pipe 114, the elastic member 112 expands in a convex shape downward as shown in FIG. Due to the expansion of the elastic member 112, the dicing tape 4 is pressed against the wafer 1, and the wafer 1 is adhered to the dicing tape 4. The pressurized gas to be injected is preferably dry air or inert gas, but is not particularly limited.

  A plurality of dicing tape frames 5 shown in FIG. 5 are stored in the frame cassette 120 shown in FIGS. The dicing tape frame 5 is housed in the frame cassette 120 in the front and back direction shown in FIG. The frame cassette 120 is placed on a frame cassette stage 121 and can be moved up and down by an elevator 124. The dicing tape frame 5 stored in the frame cassette 120 is pulled out from the frame cassette 120 by a push-pull clamp 122. The push-pull clamp 122 moves in the Y direction in the groove 123 provided in the apparatus base 10 a while holding the dicing frame portion of the dicing tape frame 5. When the dicing tape frame 5 is gripped by the push-pull clamp 122, the elevator 124 moves up and down, and the height of the dicing tape frame 5 housed in the frame cassette 120 is adjusted to the position of the push-pull clamp 122.

  The dicing tape frame 5 pulled out from the frame cassette 120 by the push-pull clamp 122 is gripped by the frame clamp 135 and conveyed to a position indicated by G in FIG. The frame clamp 135 is attached to the frame clamp arm 131, and one end of the frame clamp arm 131 is fixed to the lower end of the cylinder rod 134. The cylinder rod 134 can freely enter and exit from the frame clamp cylinder 133. The movement of the cylinder rod 134 is controlled by an actuator (not shown) built in the frame clamp cylinder 133. By the movement of the cylinder rod 134, the position of the frame clamp arm 131 in the vertical direction can be adjusted. The frame clamp cylinder 133 is fixed to the arm support base 136, and the arm support base 136 is fixed to the rotating shaft 137 supported by the support portion 138. The rotation shaft 137 is driven and rotated by a frame clamp rotation motor 132 fixed to the support portion 138. Accordingly, the arm support base 136 rotates, and at the same time, the frame clamp arm 131 rotates. The support portion 138 is attached to the frame feed mechanism 130 so as to be movable in the extending direction (the direction toward the index table 41 or the direction retracted from the index table 41). The frame feed mechanism 130 incorporates a ball screw feed mechanism therein, and the movement of the support portion 138 relative to the frame feed mechanism 130 is performed by this ball screw feed mechanism. The frame feed mechanism 130 is fixed to the apparatus base 10a at the end away from the index table 41, and a gap (not shown) is provided between the frame feed mechanism 130 and the apparatus base 10a at other portions. The frame clamp arm 131 is structured to be able to rotate through this gap.

  According to the embodiment described above, the processing axes for the wafer are arranged from the first to the third. In this embodiment, the first machining axis is a combination of rough grinding, the second machining axis is finish grinding, and the third is polishing by dry polishing. According to this aspect, for example, a wafer having a thickness of around 700 μm is finally thinned to a thickness of about 50 μm by grinding by rough grinding and finish grinding. And the mechanical damage layer by grinding is removed by dry polishing.

  The number of processing axes for the wafer is not limited to the three axes in the present embodiment. Further, the combination is not limited to the above combination. For example, the processing axes for grinding can be set to a number other than two axes. Further, the processing axes for polishing can be two or more axes. If the wafer can be thinned and the damage on the surface layer can be removed, all the processing axes can be formed only by grinding, or a processing technique different from the present embodiment can be used. Such processing techniques include chemical etching (wet, plasma) and chemical mechanical polishing. A plurality of these processing techniques can be combined as appropriate.

  In addition, since the frame cassette stage 121 is vertically indexed by the elevator 124, a plurality of cassettes can be stacked and stacked as necessary to increase the number of dicing tape frames accommodated.

(Operation of processing equipment)
Hereinafter, an example of the process of thinning the wafer and further attaching a dicing tape will be described using the processing apparatus shown in FIGS. Prior to the processing step, the wafer carrier 11 containing the required number of wafers shown in FIG. 1 is set on the wafer carrier stage 12. Further, the frame cassette 120 containing the required number of dicing tape frames 5 shown in FIG. 5 is set on the frame cassette stage 121. The wafer 1 is stored in the wafer carrier 11 with the front side facing up, and the dicing tape frame 5 is stored in the frame cassette 120 with the side on which the dicing tape 4 is attached facing up.

  When the processing is started, first, the first wafer is pulled out from the wafer carrier 11 by the multi-indirect robot 13. At this time, the articulated robot 13 vacuum-sucks the wafer with the back side of the wafer placed on the pad 13 a and pulls the wafer out of the wafer carrier 11. Then, in a state where the wafer is vacuum-sucked to the pad 13a, the front and back of the pad 13a are reversed. Thereby, the surface (front side) on which the device is formed is on the lower side of the wafer, and the rear side is adsorbed to the pad 13a from above. In this state, the wafer is placed on the positioning stage 20. That is, the wafer 1 shown in FIG. 1 is placed on the positioning stage 20 with the surface on which the device is formed facing down and the surface on which the device is not formed facing up.

  In the positioning stage 20, a plurality of positioning pins 22 arranged near the outer edge of the wafer are simultaneously driven toward the center of the wafer, so that the rotation center of the table 20a of the positioning stage 20 and the wafer center coincide. Thereafter, the wafer is vacuum-sucked and fixed to the table 20a. Then, the position of the notch of the wafer is detected by the notch sensor 21 while rotating the table 20a. Next, the table 20 a is rotated so that the detected notch of the wafer is positioned 180 ° opposite to the rotation center of the index table 41 when placed on the chuck table 40. Thereafter, the transfer arm 31 is moved to attract the transfer pad 30 to the back side of the wafer. Next, the vacuum suction state of the table 20a is released, and the transfer arm 31 is moved to transfer the wafer to the chuck table 40 located at the position A in FIG. When the wafer is placed on the chuck table 40 located at the position A, the wafer is sucked and fixed to the chuck table 40. Thus, the first wafer is placed on the index table 41.

  When the wafer is placed on the chuck table 40, the notch of the wafer is positioned 180 ° opposite to the rotation center of the index table 41. In order to align the orientation of the wafer with respect to the dicing tape frame 5. In order to realize this object, after the processing at the positions indicated by B, C, D, and E is completed, the chuck table 40 has the notch 1b of the wafer 1 shown in FIG. Stop so that it is positioned 180 ° opposite.

  Next, the index table 41 is rotated 360 ° / 7 clockwise to move the first wafer to a position below the first processing unit 50 (position B in FIG. 3). Then, grinding processing (rough grinding) is performed on the back side of the first wafer by the first processing unit 50. While this grinding process is being performed, a second wafer is placed on the chuck table 40 located at the position A, and is sucked and fixed thereto. The procedure until the wafer is placed on the chuck table 40 is the same as that for the first wafer. When the back side of the first wafer is ground to a predetermined thickness, the rough grinding using the first processing unit 50 is finished. At this time, the chuck table 40 stops so that the position of the notch 1b of the wafer is positioned 180 ° opposite to the rotation center of the index table 41. This control is performed by the function of an AC servo motor with an encoder. Thereafter, the spindle 51 is retracted upward, and the index table 41 is rotated 360 ° / 7 clockwise. As a result, the first wafer moves to the position C in FIG. 3, and the second wafer moves to the position B.

  Next, finish grinding using the second processing unit 70 for the first wafer is performed at the position C, and at the same time, roughing using the first processing unit 50 for the second wafer is performed at the position B. Grinding is performed. While these grinding operations are being performed, the third wafer is placed on the chuck table 40 located at the portion A and is adsorbed and fixed thereto. Even at the position C, the chuck table 40 is stopped so that the position of the notch of the wafer is positioned 180 ° opposite to the rotation center of the index table 41 after finishing grinding. When both grinding operations are completed, the spindle 51 and the spindle 71 are retracted upward, and the index table 41 is rotated 360 ° / 7 clockwise. As a result, the first wafer moves to the position D in FIG. 3, the second wafer moves to the position C, and the third wafer moves to the position B.

  At the position D, the first wafer is polished by the third processing unit 80, and at the position C, the second wafer is finish-ground by the second processing unit 70, At the same time, rough grinding by the first processing unit 50 is performed on the third wafer at the position B. And while these processes are performed, the 4th wafer is mounted on the chuck table 40 located in A part, and is adsorbed and fixed there. Even at the position D, the chuck table 40 stops so that the position of the notch of the wafer is positioned 180 ° opposite to the rotation center of the index table 41 after the polishing is completed. When all of the processes that are proceeding simultaneously are completed, the spindle 51, the spindle 71, and the spindle 81 are retracted upward, and the index table 41 is rotated 360 ° / 7 clockwise. As a result, the first wafer moves to the position E in FIG. Further, the wafers at positions A to C move to positions B to D, respectively.

  The first wafer moved to the position E is cleaned using the wafer cleaning pad 90. The cleaning is performed while rotating both the wafer cleaning pad 90 and the chuck table 40 in the same direction or in the reverse direction and supplying cleaning water from a cleaning water supply unit (not shown). By this cleaning, fine grinding scraps and polishing scraps are removed. Simultaneously with this cleaning process, the wafers located at locations B to D are processed at each position. Further, a new wafer (fifth wafer) is placed on the chuck table 40 at the position A, and is attracted and fixed thereto. Even at the position E, the chuck table 40 stops so that the position of the notch of the wafer is positioned 180 ° opposite to the rotation center of the index table 41 after the cleaning is completed.

  The first wafer that has been cleaned is moved to the position F by the 360 ° / 7 clockwise rotation of the index table 41. At the position F, an adhesive film for bonding attached to the base sheet 106 having a release function is attached to the back side of the first wafer. At this time, the wafers located at locations B to E are processed at each position. Further, a new wafer (sixth wafer) is placed on the chuck table 40 at the position A, and is attracted and fixed thereto. In the process at the position F, the chuck table 40 does not rotate. Thereafter, the index table 41 is rotated 360 ° / 7 clockwise. As a result, the first wafer moves from the position F in FIG. The wafers at positions A to E move to positions B to F, respectively.

  Next, a dicing tape is attached to the first wafer moved to the position G in FIG. In this step, first, the dicing tape frame 5 (see FIG. 5) is grasped from the frame cassette 120 by the push-pull clamp 122 and pulled out to the position indicated by reference numeral 5a in FIG. At this time, the frame cassette 120 is moved up and down by the elevator 124, and the height of the dicing tape frame 5 in the frame cassette 120 is adjusted to the height of the push-pull clamp 122.

  The dicing tape frame drawn to the position of reference numeral 5 a is separated from the push-pull clamp 122 and is gripped by the frame clamp 135. From this state, the frame clamp 135 rotates 180 ° − (360 ° / 7) clockwise. By this rotation, the dicing tape frame moves to the position of 5b. This rotation is performed by the arm support base 136 being rotated by the frame clamp rotation motor 132 shown in FIG. 2, and the frame clamp cylinder 133, the cylinder rod 134, and the frame clamp arm 131 are accordingly rotated. The range of this rotation is calculated by 180 ° − (360 ° / n) where n is the number of chuck tables equally arranged on the index table 41.

  The dicing tape frame that has moved to the position 5b shown in FIG. 3 is conveyed above the position G (position 5c) by the action of a ball screw feed mechanism (not shown) in the frame feed mechanism 130. At this time, the support portion 138 shown in FIG. 2 moves in the extending direction with respect to the frame feed mechanism 130, and the arm support base 136, the frame clamp cylinder 133, the cylinder rod 134, and the frame clamp arm 131 are similarly moved accordingly. Moving.

  With the dicing tape frame positioned at the position 5c in FIG. 3, the dicing tape is attached to the back surface of the first wafer positioned at the position G. At this time, first, the height of the frame clamp 135 is adjusted, and the position of the lower end surface of the frame mount unit 111 is adjusted to obtain the state shown in FIG. FIG. 6A shows a state in which the tip of the convex portion of the balloon-like elastic member 112 that has been deformed slightly convex by gravity is in contact with the dicing tape 4. Further, a state where a slight gap is formed between the dicing tape 4 and the wafer 1 is shown. At this time, the height of the dicing tape 4 is adjusted to a height of several millimeters from the back surface of the wafer 1. Further, the frame mount unit 111 fixed to the frame mount base 110 is lowered to the position shown in FIG. 6A by a vertical movement drive mechanism (not shown). The height of the frame mount unit 111 at this time is such that when the pressure gas is injected into the elastic member 112 on the bottom surface of the frame mount unit 111, the elastic member 112 that is elastically deformed can cover at least the entire back surface of the wafer 1. And

  When the state shown in FIG. 6A is obtained, high-pressure gas is injected into the elastic member 112 from the air supply pipe 114 to expand the elastic member 112. As the elastic member 112 expands, the downwardly convex shape expands downward, and the dicing tape 4 is pushed downward by the expanded elastic member 112. When the elastic member 112 is expanded, as shown in FIG. 6B, first, the dicing tape 4 comes into contact with the center of the wafer 1, and the contact portion spreads out concentrically around the periphery. Then, when the elastic member 112 swells to some extent, the dicing tape 4 is pressed and adhered to the entire back surface of the wafer 1 as shown in FIG. At this time, the cylinder rod 134 is extended downward according to the expansion of the elastic member 112, and the height position of the dicing tape frame 4 is gradually lowered. As a result, it is possible to prevent the dicing tape 4 from being deformed, and to prevent poor adhesion between the wafer 1 and the dicing tape 4. At this time, the frame mount unit 111 may be lowered or raised in parallel with the expansion of the elastic member 112 so that the adhesion between the wafer 1 and the dicing tape 4 is further controlled.

  When the state shown in FIG. 6C is obtained, the high pressure state inside the balloon-like elastic member 112 is released, and the frame mount unit 111 is retracted upward. Next, the vacuum suction state of the chuck table 40 is released and the frame clamp arm 131 is slightly raised. In this way, a state is obtained in which the back side of the wafer 1 (first wafer) is attached to the lower side of the dicing tape 4 of the dicing tape frame 5.

  At the position G described above, the chuck table 40 does not rotate. Therefore, the dicing tape 4 is attached to the wafer 1 in a state where the position of the notch 1b of the wafer 1 shown in FIG. For this reason, the position of the notch 1b with respect to the dicing tape frame 5 is always a constant position in each wafer.

  Returning to FIG. 2 and FIG. 3, the first wafer attached to the dicing tape follows the path opposite to the previous one along with the dicing tape frame and is conveyed to the frame cassette 120. That is, the dicing tape frame to which the first wafer is attached is conveyed from the position 5c in FIG. 3 to the position 5b, and the frame clamp 135 is rotated 180 °-(360 ° / 7) counterclockwise. ) It is conveyed to the position of 5a by rotating. The dicing tape frame conveyed to the position indicated by reference numeral 5a is conveyed to the frame cassette 120 by the push-pull clamp 122 and stored therein.

  At the same time as the process at position G in FIG. 3, the processes at positions B to F are also performed. During these processes, the seventh wafer is pulled out from the wafer carrier 11, placed on the chuck table 40 located at the position A, and fixed thereto by suction.

  After the first wafer adhered to the dicing tape is stored in the frame cassette 120 together with the dicing tape frame, the frame cassette 120 is moved up and down as appropriate, and the next dicing tape frame is moved to the position G by the above-described transporting process. It is conveyed to. And the process of sticking the 2nd wafer on a dicing tape is performed.

  By repeating the operations described above, the wafers stored in the wafer carrier 11 are successively transferred onto the index table 41, and each process is sequentially performed while the index table 41 is appropriately rotated. That is, thinning of the wafer by grinding at positions B and C, polishing of the thinned wafer at position D, cleaning of the wafer at position E after polishing, bonding for bonding to the back surface of the wafer at position F The attachment of the film and the attachment to the dicing tape on the back surface of the wafer at the position G are sequentially performed as the index table 41 rotates. Then, the thinned wafers adhered to the dicing tape are sequentially stored in the frame cassette 120.

  According to the above operation, a series of steps of grinding → polishing → cleaning → adhesion bonding adhesive film for chip stacking → dicing tape attachment is sequentially performed with the wafer being sucked and fixed to the chuck table. . Between these steps, it is not necessary to release the thinned wafer from the vacuum suction state and then transport it by the transport means. Therefore, it is possible to prevent the thinned wafer from being damaged in the previous stage of the attaching process to the dicing tape. When the wafer attached to the dicing tape is released from the state of being adsorbed and fixed to the chuck table and transported, the wafer is held on the surface by the dicing tape as an elastic member. Since the dicing frame having a sufficient strength is used for conveyance, stress that induces breakage is not applied to the wafer, and damage to the wafer hardly occurs.

  In addition, the dicing tape is attached to the wafer by expanding the area to be pressed concentrically from the center to the periphery using the expansion of the balloon-like elastic member. Can be prevented and strong stress can be prevented from being applied to the wafer. For this reason, the adhesiveness of the dicing tape to the wafer can be made good without damaging the wafer which is easily damaged by being thinned and stressed.

  The present invention can be used in a processing apparatus for thinning a semiconductor wafer.

It is the perspective view and side view which show notionally the semiconductor wafer in which the semiconductor device was formed. It is a perspective view which shows the outline | summary of the processing apparatus using invention. It is the top view which looked at the processing apparatus using invention from the upper surface. It is the perspective view (A) and side view (B) which show a part of means to perform a grinding process. They are the top view (A) which shows the dicing tape frame of the structure which stuck the dicing tape on the dicing frame, and the sectional view (B) of the BB line. It is an operation | movement figure which shows the outline | summary of operation | movement of a frame mount unit.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Wafer, 3 ... Dicing frame, 4 ... Dicing tape frame, 5 ... Dicing tape frame, 10a ... Apparatus base, 20 ... Positioning stage, 31 ... Transfer arm, 40 ... Chuck table (suction table), 41 ... Index table, 50 ... 1st processing unit ( grinding means), 70 ... 2nd processing unit ( grinding means), 84 ... Polishing wheel, 90 ... Wafer cleaning pad, 101 ... Sticking roller (sticking means), 111 ... Frame mount unit (wafer) Mounting means) .

Claims (1)

A processing apparatus for thinning a semiconductor wafer,
An index table rotatably provided on the device base ;
A plurality of suction tables arranged on the index table along the rotation direction of the index table and fixing the wafer in a direction to expose the back surface thereof,
A plurality of means for sequentially performing a predetermined process on the wafer, which is disposed around the index table on the apparatus base along the rotation direction of the index table and is suction-fixed to the suction table;
With
The means is
A positioning stage for positioning the wafer at a transfer start position to the suction table;
A transfer arm that moves the wafer from the positioning stage to the suction table in a direction to expose the back surface thereof;
Grinding means for grinding and thinning the back surface of the wafer;
A polishing wheel for polishing the back surface of the wafer ground by the grinding means;
A cleaning pad for cleaning the wafer polished by the polishing wheel;
An adhering means for adhering an adhesive film for bonding to the back side of the wafer cleaned with the cleaning pad;
A dicing tape in which a dicing frame having rigidity is attached to the peripheral portion is pressed against the back side of the wafer by the elastic member protruding from the center on the back side of the wafer to which the adhesive film attaching means for bonding is attached. And a wafer mounting means for attaching.

Images