JP2009090389A - Wafer grinder - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve production efficiency and quality of a wafer by simplifying adjustment of inclination of a rotation axis of a grinding means in a grinder for grinding a rear face of the wafer. <P>SOLUTION: A grinding unit 30 is equipped with an inclination adjustment mechanism 100 for tilting the rotation axis 30a and a grinding condition storage means 110 for storing angle adjustment values corresponding to various grinding conditions. By selecting a grinding condition of the wafer 1 by the storage means 110, the angle adjustment value of the grinding unit 30 is read. A back-and-forth adjustment spacer 101 and a right-and-left adjustment spacer 105 of the inclination adjustment mechanism 100 are operated based on the angle adjustment values, whereby the grinding unit 30 is adjusted to an angle of gradient corresponding to the grinding condition of the wafer 1. By grinding the wafer 1 by the grinding unit 30 after adjusting the angle of the unit 30, the wafer 1 with a desired thickness can be obtained. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a grinding apparatus for grinding and thinning a wafer, and more particularly to a grinding apparatus capable of adjusting the angle of a grinding surface of a grinding means for grinding a wafer.

  A semiconductor chip having an electronic circuit such as an IC or LSI formed on its surface is now indispensable for downsizing various electric / electronic devices. A semiconductor chip is a disk-shaped semiconductor wafer (hereinafter referred to as a wafer), which is divided into grid-like rectangular areas with planned cutting lines called streets, and an electronic circuit is formed on these rectangular areas. It is manufactured in the process of cutting and dividing.

  In such a manufacturing process, before the wafer is divided into semiconductor chips, the back surface opposite to the device surface on which the electronic circuit is formed is ground by a grinding apparatus and thinned to a predetermined thickness. Yes. The purpose of backside grinding is to further reduce the size and weight of electronic equipment and to improve heat dissipation and maintain performance. For example, from the initial thickness of around 700 μm to a thickness of 50 μm or less Thinning is performed.

  Wafer grinding processing equipment exposes the back side to the holding surface of a vacuum suction chuck table, which is a wafer holding means, sucks and holds the wafer, and rotates the grinding stone of the grinding means placed opposite the chuck table at high speed. In general, it is pressed against the back surface while grinding. When a wafer is supplied to such a grinding apparatus, the surface of the wafer is covered with a protective member, and the electronic circuit is damaged by the surface directly contacting the holding surface of the chuck table or contaminated by grinding waste liquid. Is prevented. As a commonly used protective member, for example, there is a protective tape having a configuration in which an adhesive of about 10 μm is applied to one side of a base of polyethylene or polyolefin sheet having a thickness of about 100 to 200 μm. The protective tapes are selected and used depending on the device formation status, with different thicknesses and elasticity of the base material and adhesive material. For example, when protruding electrodes are formed on the device formed on the surface of the wafer, the protective tape has a large thickness of adhesive or base material to buffer the influence of unevenness such as this electrode A thing with a big thing and elasticity is used. Such a relatively thick and elastic protective tape has a larger amount of elastic deformation when a processing load is applied to the wafer than a thin protective tape having a low elasticity.

  By the way, in the in-feed grinding in which the wafer is processed while rotating, there is a difference in the work amount per unit time between the vicinity of the center of rotation and the vicinity of the outer periphery. As a general tendency, the machining load increases from the center of rotation to the outer periphery. That is, the amount of elastic deformation of the protective tape covering the wafer surface with the processing load increases in proportion to the distance from the rotation center. For this reason, the wafer sinks in the outer peripheral portion as compared with the vicinity of the rotation center, and the amount of grinding in the thickness direction decreases. As a result, the thickness of the wafer after grinding increases in proportion to the distance from the rotation center, and a uniform thickness cannot be obtained. This tendency becomes more prominent as the thickness and elasticity of the protective tape are increased. The same tendency appears as the outer diameter of the wafer is increased.

  As described above, the type of the protective tape and the outer diameter of the wafer are factors that must be considered as conditions for grinding when the thickness of the wafer after grinding is made uniform. Therefore, in order to make the thickness of the wafer after grinding uniform, there is a method of grinding by tilting either the rotating shaft of the grinding means or the rotating shaft of the chuck table holding the wafer to an angle suitable for each condition. Conceivable. By tilting the rotation axis to an angle suitable for each condition, the amount of wafer grinding at a given time can be made uniform at each point, minimizing variations in thickness. it can. A grinding apparatus having such a configuration is known, for example, in Patent Documents 1 and 2.

JP-A-8-90376 JP-A-57-132969

  In Patent Documents 1 and 2, the operator manually adjusts the inclination of the rotating shaft of the holding means or the grinding means in accordance with the above conditions. In order to make the wafer thickness uniform using such a grinding apparatus, the operator must be familiar with the inclination angle corresponding to the grinding conditions. Thus, it is not easy for anyone to adjust the inclination of the grinding means, and skill is required.

  Therefore, according to the present invention, the inclination of the rotation axis of the grinding means can be easily adjusted, and the rotation axis of the grinding means is adjusted to an inclination suitable for the grinding conditions of each wafer and ground to obtain a uniform thickness. An object of the present invention is to provide a grinding apparatus that can finish the process.

  The grinding apparatus of the present invention includes a rotatable holding means having a holding surface for holding a wafer having a device formed on the front surface and a protective member coated on the front surface in a state where the back surface is exposed, and the holding of the holding means. Grinding means that is disposed opposite to the surface and has a rotation axis parallel to the rotation axis of the holding means, an inclination adjusting means that adjusts the inclination of the rotation axis of the grinding means to an arbitrary angle, and the holding means and the grinding means In a wafer grinding apparatus, the wafer grinding apparatus further comprises a feeding means for reducing the thickness of the wafer by grinding the back surface of the wafer by the grinding means when approaching and separating from each other by relatively moving along the rotation axis of the means Grinding condition storage means for storing the grinding conditions of the grinding means is provided, and the inclination adjusting means is used to adjust the inclination angle of the rotation axis of the grinding means stored in the grinding condition storage means. It is characterized in that the inclination of the rotation axis of the grinding means is adjustable.

  According to the grinding apparatus of the present invention, the inclination angle of the rotating shaft of the grinding means can be adjusted by the inclination adjusting means and the grinding condition storage means. That is, each grinding condition of the wafer and the inclination angle of the grinding means corresponding to each grinding condition are previously stored in the grinding condition storage means, and the grinding condition is selected by selecting the grinding condition when grinding the wafer. An inclination angle corresponding to is selected. In the grinding apparatus of the present invention, self-grinding for adjusting the holding surface of the holding means to be flat is performed every certain period of use. Based on the in-plane thickness variation obtained by grinding the dummy wafer after self-grinding, the inclination of the grinding means is adjusted by the tilt adjusting mechanism so that the in-plane variation of the wafer becomes uniform as appropriate. If the wafer is ground by tilting the grinding means along the selected tilt angle based on the adjusted tilt, the surface of the wafer is not affected by additional factors such as the protective member used. It is possible to finish the inner thickness variation uniformly or finish the wafer with a desired thickness distribution. Therefore, even if an inexperienced worker does not require skill as in the prior art, if the grinding means is tilted along the inclination angle selected by the grinding condition storage means, the wafer thickness is uniformly finished. be able to. As a result, the inclination angle of the grinding means can be easily adjusted in accordance with the grinding conditions, and work time loss and human error can be suppressed.

  The grinding conditions of the present invention include the type of the protective member, the outer diameter of the wafer, or an additional process for the wafer after grinding. That is, the inclination angle of the holding means stored in the grinding condition storage means is determined according to the type of the protective member, according to the outer diameter of the wafer, or according to the additional process after grinding. The main factors causing variations in the thickness of the wafer are due to the type of the protective member and the outer diameter of the wafer. Therefore, it is necessary to collect in advance data on wafer thickness variations caused by differences in the type of protective tape and the outer diameter of the wafer during grinding, and store them in the grinding condition storage means. The additional process after the grinding process is a polishing process for removing a mechanical damage layer remaining on the processed surface of the wafer mainly by the grinding process, but also includes a chemical etching process such as dry etching. Even in this polishing process, the wafer thickness varies depending on each condition of the wafer. Therefore, the wafer thickness is previously varied by grinding in anticipation of the thickness variation. As a result, a wafer having a uniform thickness can be obtained after polishing. In this way, quality can be improved by collecting, analyzing, and feeding back data on various wafer grinding conditions.

  Further, the grinding conditions of the present invention include the grinding amount of the grinding means for the wafer, the crystal characteristics of the wafer, the type of grindstone used for the grinding means, or the surface condition of the surface to be ground of the wafer. That is, the inclination angle of the grinding means stored in the grinding condition storage means is in accordance with the amount of grinding with respect to the wafer, in accordance with the crystal characteristics of the wafer, in accordance with the type of grinding wheel used in the grinding means, or It depends on the surface condition of the surface to be ground of the wafer.

  Of the above grinding conditions, the amount of grinding of the wafer is not the amount of grinding, but the degree of grinding of how much grinding is currently being done with respect to the original wafer thickness. For example, it is divided into the initial stage of grinding and the middle stage. In the initial stage of grinding (for example, a stage of grinding a thickness of about 5 to 10 μm), the grinding resistance received by the grinding means from the wafer is not large, and the grinding means transfers the surface to be ground relatively accurately. Therefore, it is not necessary to adjust the inclination of the holding means at the beginning of grinding. However, the grinding resistance increases after the middle period when the grinding amount increases and the grinding amount increases, and the thickness varies depending on the resistance, for example, the cross-sectional shape of the wafer becomes a concave cross-sectional shape that is ground at the center. Arise. In order to correct such a bias, it is the present invention that the inclination of the holding means is appropriately adjusted.

  The crystal characteristics of a wafer under the above-mentioned grinding conditions are crystal characteristics of a semiconductor wafer such as a silicon wafer, and such a wafer is called a low resistance product containing a large amount of impurities such as boron, or has few impurities. There are high resistance products. As a general tendency, the low resistance product is harder to grind than the high resistance product, and the wafer is easily ground into a concave cross section. In the present invention, the inclination of the grinding means is appropriately adjusted in advance according to such a tendency.

  In the case where the grinding means includes a grindstone and grinding is performed while pressing the grindstone against the wafer, it is desirable to adjust the inclination of the grinding means depending on the type of the grindstone. Grinding stones for grinding silicon wafers are generally limited to diamond, but there are several types of binders for forming abrasive grains into grinding stones, such as resinoid resin and vitrified glassy ceramics. In addition, the content (concentration) of the abrasive grains per unit volume of the grinding wheel, the grain size of the abrasive grains, the density and hardness of the grinding stone, and other factors determine the characteristics of the grinding wheel, such as processing ability and wear resistance. ing. Therefore, the cross-sectional shape of the wafer to be ground varies depending on the type of grindstone, that is, the processing capability and wear resistance, and the inclination of the grinding means is adjusted accordingly. Is the present invention.

  Further, the surface condition of the surface to be ground of the wafer under the above grinding conditions refers to the degree of surface roughness and minute unevenness. The surface to be ground of the wafer to be ground may be treated with a chemical solution, and the surface state (surface roughness and minute unevenness) varies depending on the type of the chemical solution. This is reflected in the difference in cross-sectional shape. For this reason, it is the present invention that the inclination of the grinding means is appropriately adjusted according to the surface state of the surface to be ground of the wafer.

  According to the present invention, it is possible to minimize variations in wafer thickness caused by differences in the type of protective tape during grinding and to easily tilt the rotation axis of the grinding means without requiring skill. Can be adjusted to an angle suitable for each grinding condition. As a result, it is possible to minimize work time loss and human error, and to improve work efficiency.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
[1] Semiconductor Wafer Reference numeral 1 in FIG. 1 indicates a disk-shaped semiconductor wafer (hereinafter abbreviated as a wafer) whose back surface is ground and thinned by the grinding apparatus of the embodiment shown in FIG. The wafer 1 is a silicon wafer or the like, and the thickness before processing is, for example, about 700 μm. A plurality of rectangular semiconductor chips 3 are partitioned on the surface of the wafer 1 by grid-like division planned lines 2. An electronic circuit (not shown) such as an IC or an LSI is formed on the surface of the semiconductor chip 3. A V-shaped notch 4 indicating the crystal orientation of the semiconductor is formed at a predetermined location on the peripheral surface of the wafer 1. The wafer 1 is finally cut and divided along the planned division line 2 and is divided into a plurality of semiconductor chips 3.

  When the back surface of the wafer 1 is ground, a protective tape 5 (protective member) is adhered to the surface on which the electronic circuit is formed as shown in FIG. 1B for the purpose of protecting the electronic circuit. The As the protective tape 5, for example, a structure in which an adhesive of about 10 μm is applied to one side of a soft resin base sheet such as polyolefin having a thickness of about 100 to 200 μm is used. It is pasted. The wafer 1 is thinned down to 50 μm or 30 μm, for example, by backside grinding with a grinding apparatus shown in FIG.

[2] Grinding Device Next, a grinding device according to an embodiment for grinding the back surface of the wafer 1 shown in FIG. 1 will be described.
FIG. 2 shows the entire grinding apparatus 10, which includes a rectangular parallelepiped base 11 having a horizontal upper surface. In FIG. 2, the longitudinal direction, the width direction, and the vertical direction of the base 11 are shown as a Y direction, an X direction, and a Z direction, respectively. At one end portion of the base 11 in the Y direction, a column 12 arranged in the X direction is erected in a pair. On the base 11, a processing area 11A for grinding the wafer 1 is provided on the column 12 side in the Y direction, and the wafer 1 before processing is supplied to the processing area 11A on the side opposite to the column 12, and An attachment / detachment area 11B for collecting the processed wafer 1 is provided.
Hereinafter, the grinding area 11A and the attachment / detachment area 11B will be described.

(I) Grinding area In the grinding area 11A, a disk-shaped turntable 13 whose rotation axis is parallel to the Z direction and whose upper surface is horizontal is rotatably provided. The turntable 13 is rotated in the direction of arrow R by a rotation drive mechanism (not shown). A plurality of (in this case, three) disk-shaped chuck tables 20 (holding means) are rotatably disposed on the outer peripheral portion of the turntable 13 at equal intervals in the circumferential direction.

  These chuck tables 20 are of a generally known vacuum chuck type, and suck and hold the wafer 1 placed on the upper surface. As shown in FIG. 3B, the chuck table 20 has a circular suction area 21 made of porous ceramic on the upper surface, and the wafer 1 is sucked and held on the upper surface 21 a of the suction area 21. It has become so. An annular frame 22 is formed around the suction area 21, and an upper surface 22 a of the frame 22 is continuous with the upper surface 21 a of the suction area 21 and forms the same plane. Each chuck table 20 is independently rotated or rotated in one direction or both directions by a rotation drive mechanism (not shown) provided in the turntable 13, and revolves when the turntable 13 rotates. It becomes a state.

  As shown in FIG. 2, in a state where two chuck tables 20 are arranged in the X direction on the column 12 side, grinding units 30 (grinding means) are respectively disposed immediately above the chuck tables 20. Each chuck table 20 is positioned at three positions, that is, a grinding position below each grinding unit 30 and an attachment / detachment position closest to the attachment / detachment area 11 </ b> B by rotation of the turntable 13. There are two grinding positions, and a grinding unit 30 is provided for each of these grinding positions. In this case, the grinding position on the upstream side (back side in FIG. 2) in the transfer direction indicated by the arrow R of the chuck table 20 by the rotation of the turntable 13 is the primary grinding position, and the downstream grinding position is the secondary grinding position. .

  A slider 40 is attached to the column 12 so as to be movable up and down. The slider 40 is slidably mounted on a guide rail 41 extending in the Z direction, and can be moved in the Z direction by a ball screw type feed mechanism 43 (feed means) driven by a servo motor 42. The front surface 40a on the front side in the Y direction of each slider 40 is a vertical surface with respect to the upper surface of the base 11, but tapers back obliquely at a predetermined angle toward the back side from the end in the X direction toward the center. Formed on the surface.

  The grinding unit 30 is attached to the taper surface 40 a of the slider 40 via an inclination adjustment mechanism 100. The mounting structure of each grinding unit 30 to each column 12 is the same and is bilaterally symmetrical in the X direction. Each grinding unit 30 is moved up and down in the Z direction by the feed mechanism 43 and lowered to grind the exposed surface of the wafer 1 held on the chuck table 20 by a feed operation approaching the chuck table 20. Further, the inclination of the rotating shaft 30a of the grinding unit 30 shown in FIG. 6 is adjusted by an inclination adjusting mechanism 100 (inclination adjusting means) described later.

  As shown in FIG. 3, the grinding unit 30 includes a cylindrical spindle housing 31 whose axial direction extends in the Z direction, a spindle shaft 32 coaxially and rotatably supported in the spindle housing 31, and a spindle housing. The motor 33 is fixed to the upper end of 31 and rotationally drives the spindle shaft 32, and the disk-shaped flange 34 is coaxially fixed to the lower end of the spindle shaft 32. A grindstone wheel 35 is detachably attached to the flange 34 by attachment means such as screwing.

  The grindstone wheel 35 is configured such that a plurality of grindstones 37 are annularly arranged and fixed to the lower end surface of an annular frame 36 over the entire outer periphery of the lower end surface. A grinding wheel 37 including a grinding wheel 37 containing abrasive grains # 320 to # 400 is attached to the flange 34 of the grinding unit 30 for primary grinding disposed above the primary grinding position. A grindstone wheel 35 in which a grindstone 37 contains abrasive grains of, for example, # 2000 to # 8000 or more is attached to the flange 34 of the grinding unit 30 for secondary grinding disposed above the secondary grinding position. The flange 34 and the grindstone wheel 35 are provided with a grinding water supply mechanism (not shown) for supplying grinding water for cooling and lubrication of the grinding surface or discharging grinding scraps, and a water supply line is connected to the mechanism. Yes. The grinding wheel 35 has a grinding outer diameter, that is, a diameter of the outer peripheral edge of the plurality of grinding wheels 37 is set to be equal to or larger than at least the radius of the wafer 1 and generally equal to the diameter of the wafer.

  Reference numeral 50 in FIG. 2 denotes a thickness measurement gauge configured by a combination of a reference side height gauge 51 and a wafer side height gauge 52. As shown in FIG. 3A, the reference-side height gauge 51 is configured such that the tip of the swinging reference probe 51a contacts the upper surface 22a of the frame 22 of the chuck table 20 that is not covered with the wafer 1, The height position is detected. The wafer-side height gauge 52 detects the height position of the upper surface of the wafer 1 when the tip of the oscillating variable probe 52 a contacts the upper surface of the wafer 1 held by the chuck table 20, that is, the surface to be ground. . According to the thickness measurement gauge 50, the thickness of the wafer 1 is measured based on a value obtained by subtracting the measurement value of the reference height gauge 51 from the measurement value of the wafer height gauge 52.

  The wafer 1 is first ground (roughly ground) by the grinding unit 30 at the primary grinding position, and then transferred to the secondary grinding position by rotating the turntable 13 in the R direction shown in FIG. Secondary grinding (finish grinding) is performed by the unit 30.

  FIG. 4 shows the positional relationship between the rotation trajectory 37a of the grindstone 37 and the chuck table 20 as viewed from above. As shown in FIG. 6, the suction area 21a of the chuck table 20 is formed in an umbrella shape with the center at the apex, as shown in FIG. Therefore, the region in which the wafer 1 and the grindstone 37 are in contact with each other and the grindstone 37 grinds the wafer 1 is limited to a contact area 37b indicated by a thick line from the center to the outer periphery. In addition, the inclination of the grinding unit 30 is adjusted by the inclination adjusting mechanism 100 so that the in-plane variation of the wafer becomes uniform as appropriate, based on the in-plane thickness variation obtained by grinding the dummy wafer after self-grinding. . In the present embodiment, the wafer 1 is ground by tilting the grinding unit 30 by a tilt adjustment value described later with reference to a state in which the tilt of the grinding unit 30 is adjusted so that the in-plane thickness variation is uniform. .

(II) Attachment / Removal Area As shown in FIG. 2, a two-bar link pickup robot 70 that moves up and down is installed at the center of the attachment / detachment area 11B. Around the pickup robot 70, a supply cassette 71, an alignment table 72, a supply unit 73, a cleaning nozzle 76, a recovery unit 77, a spinner type cleaning device 80, and a recovery cassette 81 are counterclockwise as viewed from above. Are arranged. The supply means 73 is made of a porous material, and includes a suction pad 74 that sucks the wafer 1 on a horizontal lower surface by a vacuum action, and a horizontal swivel-type supply arm 75 having the suction pad 74 fixed to the tip. ing. The recovery means 77 is made of a porous material, and includes a suction pad 78 that sucks the wafer 1 by a vacuum action on a horizontal lower surface, and a horizontal swivel-type supply arm 79 having the suction pad 78 fixed to the tip. It is configured. The cassettes 71 and 81 are configured to accommodate a plurality of wafers 1 in a horizontal posture and in a stacked state at regular intervals in the vertical direction, and are set at predetermined positions on the base 11.

(III) Details of Inclination Adjustment Mechanism and Grinding Condition Storage Unit Next, an inclination adjustment mechanism 100 according to the present invention will be described with reference to FIGS. 4 and 5.
The inclination adjusting mechanism 100 adjusts the front-rear adjustment spacer 101 that adjusts the inclination of the grinding unit 30 in the front-rear direction (A direction in FIG. 4) and the inclination of the grinding unit 30 in the left-right direction (B direction in FIG. 4). It is comprised by the spacer 105 for left-right adjustment. The front / rear adjustment spacer 101 is supported by front / rear support pins 102 fixed to the tapered surface 40 a of each slider 40. The front-rear adjustment spacer 101 is tiltable in the front-rear direction with the front-rear support pin 102 as a fulcrum, and the inclination is adjusted by a front-rear adjustment screw 103 that is screwed into a screw hole provided in the tapered surface 40a. The front / rear adjustment spacer 101 is provided with a front / rear fixing screw 104 next to the front / rear adjustment screw 103. By pressing the front / rear fixing screw 104 against the tapered surface 40a, the front / rear adjustment spacer 101 swings in the front / rear direction. It is fixed without.

A left and right support pin 106 is provided substantially at the center of the surface of the front and rear adjustment spacer 101, and the left and right adjustment spacer 105 is tiltably supported by the left and right support pin 106. That is, the left / right adjustment spacer 105 can tilt along a plane parallel to the tapered surface 40a. Long left and right elongated holes 107 are formed at the left and right ends of the upper portion of the left / right adjustment spacer 105. The left and right fixing screws 108 pass through the long holes 107 and are screwed into screw holes 101 a formed on the surface of the front / rear adjustment spacer 101. By tightening the left and right fixing screws 108, the left and right adjustment spacers 105 are fixed to the front and rear adjustment spacers 101.

  The grinding apparatus 10 is connected to grinding condition storage means 110 for storing various wafer grinding conditions. In this case, as shown in FIG. 10, the grinding condition storage means 110 inputs in advance the type of the protective tape, the diameter of the wafer, and the presence / absence of polishing after grinding, as shown in FIG. At the same time, the angle adjustment value of the rotating shaft 30a of the grinding unit 30 suitable for the grinding conditions is stored. This angle adjustment value indicates that the rotation axis 20a of the chuck table 20 and the rotation axis 30a of the grinding unit 30 are in parallel to incline the angle of the rotation axis 30a of the grinding unit 30 to an angle according to the grinding conditions of the wafer. It is the amount of inclination of the grinding unit 30 at the points C and D as a reference. The operator tilts the front / rear adjustment spacer 101 and the left / right adjustment spacer 105 in a direction corresponding to the angle adjustment value. The angle adjustment value can be obtained by collecting and analyzing the tendency of thickness variation caused by wafer grinding for each grinding condition.

[3] A series of operations of the grinding apparatus The above is the configuration of the grinding apparatus 10 of the present embodiment. Next, the operation of the apparatus 10 will be described.
First, the grinding condition of the wafer 1 is input to the grinding condition storage unit 110. Then, the angle adjustment value corresponding to the grinding condition of the wafer 1 is selected. Next, the front / rear adjustment spacer 101 and the left / right adjustment spacer 105 are moved based on the selected angle adjustment value, and the inclination of the rotation shaft 30a of each grinding unit 30 is adjusted. The reference inclination at this time is an inclination adjusted based on the result of grinding a dummy wafer after self-grinding, and the inclination is further adjusted based on the angle adjustment value therefrom. Next, the wafer 1 to be ground is first taken out from the supply cassette 71 by the pick-up robot 70 and placed on the alignment table 72 to be determined at a certain position. Next, the wafer 1 is picked up by the supply arm 73 from the alignment table 72 and placed on the chuck table 20 waiting at the attachment / detachment position with the surface to be ground (the back surface on which the semiconductor chip 3 is not formed) facing upward. Is done.

  The wafer 1 is transferred to the primary grinding position and the secondary grinding position in this order by the rotation of the turntable 13 in the R direction, and the surface is ground by the grinding unit 30 as described above at these grinding positions. When grinding the wafer 1, the grinding amount is controlled while measuring the thickness of the wafer 1 by the thickness measurement gauge 50 at any grinding position. The wafer 1 for which the secondary grinding has been completed is returned to the attachment / detachment position by further rotating the turntable 13 in the R direction.

  The wafer 1 on the chuck table 20 returned to the attachment / detachment position is cleaned by the cleaning nozzle 76. Next, it is picked up by the recovery arm 77, transferred to a spinner type cleaning device 80, washed with water and dried. The wafer 1 cleaned by the spinner cleaning device 80 is transferred and accommodated in the recovery cassette 81 by the pickup robot 70. The above is the overall operation of the grinding apparatus 10 of the present embodiment, and this operation is repeated to grind many wafers 1 continuously.

  According to this embodiment, by adjusting the angle of the rotating shaft 30a of the grinding unit 30 and grinding, the thickness of the wafer after grinding can be finished uniformly. As shown in FIG. 6, when the angle of the rotating shaft 30a of the grinding unit 30 is not adjusted, the wafer sinks toward the outer periphery, and the amount of grinding in the thickness direction tends to decrease. As a result, the thickness cannot be made uniform. However, in the present embodiment shown in FIG. 7, the angle of the rotating shaft 30a of the grinding unit 30 can be easily adjusted by using the inclination adjusting mechanism 100 and the grinding condition storage means 110. As a result, the thickness of the wafer 1 can be uniformly finished by inclining the rotating shaft 30a of the grinding unit 30 based on numerical values analyzed in advance as shown in FIG.

  In addition, when a polishing process, which is a subsequent process, is performed after the grinding process, the thickness of the wafer 1 after the grinding process needs to be increased, for example, as it goes to the outer peripheral portion, instead of being uniform. As a reason for this, the wafer 1 after polishing may become thinner as it goes away from the center of rotation, contrary to grinding. Therefore, as shown in FIG. 8A, the wafer 1 is ground after the rotation shaft 30a of the grinding unit 30 is tilted to an angle based on the angle adjustment value shown in FIG. As a result, a wafer 1 is obtained that becomes thicker toward the outer periphery shown in FIG. Thereafter, the wafer 1 is polished by a polishing apparatus, and the thickness becomes uniform as shown in FIG. FIG. 9A shows a part of the polishing apparatus. A polishing cloth 44 impregnated with metal oxide abrasive such as silica is rotated by a motor (not shown), and the polishing cloth 44 is pressed against the wafer 1 to polish the back surface of the wafer 1.

  According to the grinding apparatus 10 of the present embodiment, the inclination of the rotating shaft 30a of the grinding unit 30 can be adjusted by the inclination adjusting mechanism 100 and the grinding condition storage means 101. That is, by previously storing each grinding condition of the wafer 1 and the angle adjustment value of the grinding unit 30 corresponding to each grinding condition in the grinding condition storage means, by selecting the grinding condition when grinding the wafer, An angle adjustment value corresponding to the grinding condition is selected. If the rotation axis 30a of the grinding unit 30 is tilted along the selected angle adjustment value and the wafer 1 is ground, the thickness of the wafer can be finished uniformly. Therefore, if the grinding unit 30 is tilted along the angle adjustment value selected by the grinding condition storage means 110 even for an inexperienced worker without requiring skill as in the prior art, the wafer thickness can be reduced. Can be finished uniformly. As a result, the inclination of the rotating shaft 30a of the grinding unit 30 can be easily adjusted according to the grinding conditions, and loss of work time and human error can be suppressed. Further, by analyzing the grinding tendency of wafers under various conditions and feeding them back, higher quality wafers can be obtained.

  In the above embodiment, the three conditions of the type of the protective tape 5, the diameter of the wafer 1, and the presence / absence of polishing after grinding are used as the grinding conditions, and the angle adjustment value of the rotating shaft 30 a suitable for these grinding conditions is set. Although stored in the grinding condition storage means 110, in the present invention, the grinding conditions are not limited to these three conditions. In the present invention, as other grinding conditions, the grinding amount such as the thickness of the wafer 1 to be ground, the crystal characteristics of the wafer 1, the type of the grinding wheel 35, and the surface condition of the surface to be ground of the wafer 1 are ground. Conditions can be taken up, and the angle adjustment value of the rotary shaft 30a that meets these conditions is stored in the grinding condition storage means 110.

It is the (a) perspective view and (b) side view of the wafer which are ground by one Embodiment of this invention. It is a perspective view of a grinding device provided with the inclination adjustment mechanism and grinding condition storage means of the present invention. 3A is a perspective view and FIG. 3B is a side view showing a state in which a wafer surface is ground by a spindle unit provided in the grinding apparatus shown in FIG. 2. It is the top view which showed the positional relationship of the rotation locus | trajectory of the grindstone of a grinding processing apparatus, and a chuck table. It is the (a) side view and (b) front view which show the inclination adjustment mechanism with which the grinding-work apparatus shown in FIG. 2 is provided. (A) is the side view which showed a mode that the wafer was ground with the conventional grinding processing apparatus, (b) is the side view of the wafer obtained by the grinding process. (A) is the side view which showed a mode that the rotating shaft of a grinding unit was tilted by the inclination adjustment mechanism of this invention, and grinding a wafer, (b) is a side view of the wafer obtained by the grinding process. . (A) is the side view which showed a mode that a wafer was ground on the grinding conditions with a grinding | polishing process, (b) is a side view of the wafer obtained by the grinding process. (A) The side view which showed a mode that the wafer obtained in FIG. 8 was grind | polished, (b) is the side view of the wafer obtained by the grinding | polishing process. It is a table | surface which shows each grinding condition and the angle adjustment value of the rotating shaft of the grinding unit which suits the grinding condition.

Explanation of symbols

1 ... wafer 5 ... protective tape (protective member)
DESCRIPTION OF SYMBOLS 10 ... Grinding apparatus 20 ... Chuck table (holding means)
20a: Chuck table rotation axis (rotation axis of holding means)
21a ... holding surface 30 ... grinding unit (grinding means)
30a: Rotary axis of the grinding unit (rotary axis)
43 ... Feeding mechanism (feeding means)
100: Inclination adjusting mechanism (inclination adjusting means)
110: Grinding condition storage means

Claims (8)

A rotatable holding means having a holding surface for holding a wafer having a device formed on the front surface and coated with a protective member on the surface in a state where the back surface is exposed;
A grinding means disposed opposite to the holding surface of the holding means and having a rotation axis parallel to the rotation axis of the holding means;
Inclination adjusting means for adjusting the inclination of the rotating shaft of the grinding means to an arbitrary angle;
The holding means and the grinding means are moved relative to each other along the rotation axis of the grinding means to approach and separate from each other, and when approaching, the back surface of the wafer is ground by the grinding means to reduce the thickness of the wafer. In a wafer grinding apparatus having a feed means for reducing,
Grinding condition storage means for storing the grinding conditions of the wafer is provided, and the inclination of the rotation axis of the grinding means is adjusted by the inclination adjusting means based on the inclination angle of the rotation axis of the grinding means stored in the grinding condition storage means. Is a wafer grinding apparatus characterized by being adjustable.   2. The wafer grinding apparatus according to claim 1, wherein an inclination angle of the grinding means stored in the grinding condition storage means is in accordance with a type of the protection member.   2. The wafer grinding apparatus according to claim 1, wherein an inclination angle of the grinding means stored in the grinding condition storage means corresponds to an outer diameter of the wafer.   2. The wafer grinding apparatus according to claim 1, wherein an inclination angle of the grinding means stored in the grinding condition storage means corresponds to an additional step after grinding. 2. The wafer grinding apparatus according to claim 1, wherein an inclination angle of the grinding means stored in the grinding condition storage means is in accordance with a grinding amount of the grinding means with respect to the wafer.   2. The wafer grinding apparatus according to claim 1, wherein an inclination angle of the grinding means stored in the grinding condition storage means is in accordance with crystal characteristics of the wafer.   The grinding means includes a grindstone for grinding the wafer, and an inclination angle of the grinding means stored in the grinding condition storage means is in accordance with a type of the grindstone. The wafer grinding apparatus described in 1.   2. The wafer grinding apparatus according to claim 1, wherein an inclination angle of the grinding means stored in the grinding condition storage means corresponds to a surface state of a surface to be ground of the wafer.

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