JP2019115975A - Wafer grinding device - Google Patents

Abstract

To provide a wafer grinding device capable of smoothly and easily executing positioning of a grinding start position.SOLUTION: A wafer grinding device comprises: an arm 11 which is extended in a horizontal direction H; lifting/lowering means 12 for lifting and lowering the arm 11 in a vertical direction V; an upper contact sensor 13 which is disposed at an upper part of a tip of the arm 11 and detects contact with a grindstone 4; a lower contact sensor 14 which is disposed at a lower part of the tip of the arm 11 and detects contact with a wafer chuck 3; and control means which determines that a state in which the upper contact sensor 13 is in contact with the grindstone 4 and the lower contact sensor 14 is in contact with the wafer chuck 3 as a grinding start point of the grindstone 4.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a wafer grinding apparatus.

  A wafer grinding apparatus for grinding the front surface of a wafer includes a wafer chuck for holding the back surface of the wafer by suction and a grinding wheel disposed above the wafer chuck, and rotates the wafer chuck and the grinding wheel while rotating the grinding wheel It is known to grind the surface of a wafer by pressing it.

  In such a wafer grinding apparatus, it is necessary to measure the distance between the grinding wheel and the wafer chuck and register the grinding start position (zero point position) of the grinding wheel before grinding. Conventionally, the block gauge is placed on the wafer chuck, and the grinding start position of the grinding wheel is derived from the thickness (for example, 1 to 2 mm) of the known block gauge by lowering the grinding wheel until it contacts the block gauge. The

  The work of deriving the grinding start position using a block gauge is performed manually by the operator, and the block gauge is placed every time the wafer chuck or the grinding wheel is replaced, and the position where the wafer chuck and the grinding wheel are in contact is accurately determined. The burden on the operator was heavy, such as grasping and re-registration of the grinding start position.

  As a wafer grinding apparatus for reducing the burden on the operator required for deriving such a grinding start position, displacement detection means provided on a chuck table to detect vertical displacement of the chuck table, and output from the displacement detection means Treating only as the height of the grinding wheel is treated as that having control means for registering the reference position of the grinding wheel based on the displacement of the chuck table (for example, refer to Patent Document 1) or the position of the wafer chuck does not change. It is known to derive the grinding start position of the grinding wheel by measuring with a sensor or the like.

Unexamined-Japanese-Patent No. 11-198008 gazette

  However, in the former wafer grinding apparatus, it is necessary to provide a special mechanism such as a displacement detection means in the wafer chuck, so that the existing wafer chuck can not be diverted, and there is a problem that the economic burden associated with the installation of the apparatus is heavy. .

  In the latter wafer grinding apparatus, when the wafer chuck is replaced due to contact between the wafer chuck and the grindstone and the wafer chuck is replaced, the height of the wafer chuck at the reference height changes, and the wafer chuck is changed. There is a problem that it can not cope with the derivation of the grinding start position after replacement.

  Then, the technical subject which should be solved in order to perform alignment of a grinding start position smoothly and simply arises, and an object of the present invention is to solve this subject.

  The present invention has been proposed to achieve the above object, and the invention according to claim 1 is a wafer grinding apparatus for grinding a wafer by pressing a grindstone against the surface of a wafer placed on a wafer chuck, An arm horizontally extended between the wafer chuck and the grindstone, lifting means for vertically lifting the arm, and an upper contact sensor disposed on the upper surface of the arm to detect contact of the grindstone And a control unit configured to determine that the upper contact sensor is in contact with the grindstone as the grinding start position of the grindstone.

  According to this configuration, since the distance between the wafer chuck and the grindstone can be automatically measured, the positioning of the grinding start position of the grindstone can be easily performed. Further, since the grinding start position of the grindstone can be measured simply by providing the conventional wafer grinding apparatus with the arm, the lifting means and the upper contact sensor, the existing wafer grinding apparatus can be diverted to reduce the economic cost.

  According to the present invention, since the distance between the wafer chuck and the grinding wheel can be automatically measured, the alignment of the grinding start position of the grinding wheel can be easily performed. Further, since the grinding start position of the grindstone can be measured simply by providing the conventional wafer grinding apparatus with the arm, the lifting means and the upper contact sensor, the existing wafer grinding apparatus can be diverted to reduce the economic cost.

FIG. 1 is a plan view showing a wafer grinding apparatus according to an embodiment of the present invention. The elements on larger scale which show the rough grinding stage shown in FIG. The side view which shows a rough grinding stage. The flowchart which shows the process of measuring the measurement start position of a whetstone. The flowchart which shows the process of measuring the straightness of a whetstone. The flowchart which shows the process of measuring the straightness of a wafer chuck. The figure which shows the measurement point at the time of confirming the attachment state of a grindstone. The figure explaining the procedure which measures straightness based on the height of a whetstone.

  The wafer grinding apparatus according to the present invention is a wafer that presses a grindstone against the surface of a wafer mounted on a wafer chuck to grind the wafer, in order to achieve the purpose of aligning the grinding start position smoothly and easily. In a grinding apparatus, an arm horizontally extended between a wafer chuck and a grindstone, lifting means for raising and lowering the arm vertically, and an upper contact sensor disposed on the upper surface of the arm to detect contact of the grindstone The present invention is realized by providing control means for determining that the upper contact sensor is in contact with the grindstone as the grinding start position of the grindstone.

  Hereinafter, a wafer grinding apparatus 1 according to an embodiment of the present invention will be described based on FIG. In the present embodiment, the words "upper" and "lower" correspond to upper and lower sides in the vertical direction. FIG. 1 is a view showing an apparatus configuration of the wafer grinding apparatus 1.

  The wafer grinding apparatus 1 includes an INDEX table 2 capable of rotating the paper surface of FIG. 1 counterclockwise, four wafer chucks 3 arranged on the INDEX table 2 at equal intervals, and an INDEX table. 2 and the first rack 6 for containing the wafer W before processing, the second rack 7 for containing the wafer after processing, and The first arm 8 for transferring the wafer W from the rack 6 to the wafer chuck 3 and the second arm 9 for transferring the wafer W from the wafer chuck 3 to the second rack 7. In addition, the code | symbol 4a in FIG. 1 is a grindstone feeder which raises / lowers the grindstone 4 up and down. In addition, the structure of the wafer grinding apparatus 1 is not limited to said thing, For example, it is not necessary to provide a grinding | polishing stage.

  The wafer grinding apparatus 1 is provided with an alignment stage ST1, a rough grinding stage ST2, a fine grinding stage ST3, and a polishing stage ST4. Each stage is individually divided. Every time the INDEX table 2 rotates by 90 °, the wafer W is processed in the order of rough grinding, fine grinding and polishing.

  In alignment stage ST 1, first arm 8 takes out wafer W from first rack 6, and places wafer W on wafer chuck 3. The wafer W is vacuum-sucked to the wafer chuck 3 and fixed integrally with the wafer chuck 3. The second arm transports the wafer W after polishing from the wafer chuck 3 to the second rack 7. When the wafer W is attached to the wafer chuck 3, the INDEX table 2 is rotated by 90 ° counterclockwise on the paper surface of FIG. 1, and the wafer W is transferred to the rough grinding stage ST 2.

  In the rough grinding stage ST2, the grindstone 4 and the wafer chuck 3 are respectively rotated, and the grindstone 4 is pressed against the wafer W to grind the surface of the wafer W. After the rough grinding process, the INDEX table 2 is rotated 90 ° counterclockwise on the paper surface of FIG. 1, and the wafer W is transferred to the fine grinding stage ST3.

  In the fine grinding stage ST3, the grindstone 4 and the wafer chuck 3 are each rotated automatically, and the grindstone 4 is pressed against the wafer W to grind the surface of the wafer W. After the precision grinding process, the INDEX table 2 is rotated 90 ° counterclockwise on the paper surface of FIG. 1, and the wafer W is transferred to the polishing stage ST4.

  In the polishing stage ST4, the surface of the wafer W is polished to a mirror surface by rotating the polishing pad 5 and the wafer chuck 3 respectively and pressing the polishing pad 5 against the wafer W. After the polishing process, the INDEX table 2 is rotated by 90 ° counterclockwise on the paper surface of FIG. 1, and the wafer W is transferred to the alignment stage ST1.

  The operation of the wafer grinding apparatus 1 is controlled by the control means 15. The control means 15 controls each component of the wafer grinding apparatus 1. The control unit 15 is configured of, for example, a CPU, a memory, and the like. The function of the control means 15 may be realized by control using software or may be realized by operating using hardware.

  Next, the configuration of the measurement mechanism 10 disposed in the wafer grinding apparatus 1 will be described based on the drawings. Hereinafter, although the measurement mechanism disposed in the rough grinding stage ST2 will be described as an example, it goes without saying that the measurement mechanism 10 is applicable to the fine grinding stage ST3 or the polishing stage ST4. FIG. 2 is a plan view showing the rough grinding stage ST2 of the wafer grinding apparatus 1. FIG. 3 (a) is a measuring mechanism 10 showing a state in which the arm 11 is slid in the horizontal direction H, and FIG. 3 (b) is a side view showing a state in which the elevating means 12 is lowered.

  The measuring mechanism 10 includes an arm 11 extended in the horizontal direction H, lifting means 12 for moving the arm up and down in the vertical direction V, an upper contact sensor 13 disposed on the upper surface of the arm 11, and a lower surface of the arm And the lower contact sensor 14.

  The arm 11 is extended in the horizontal direction H between the wafer chuck 3 and the grinding wheel 4. The base end portion 11a of the arm 11 is connected to the air piston 12a mounted on the lifting means 12, and the arm 11 slides in the horizontal direction H according to the expansion and contraction operation of the air piston 12a in the horizontal direction H. It has become. Thereby, at the time of grinding processing, the arm 11 retracts from between the wafer chuck 3 and the grinding wheel 4 and moves to a predetermined standby position.

  The raising and lowering means 12 supports the base end 11 a of the arm 11 and raises and lowers the arm 11 by raising and lowering the rail (not shown) in the vertical direction V.

  The upper contact sensor 13 is disposed on the top end of the arm 11. The upper contact sensor 13 is a known contact sensor, and detects a contact between the upper contact sensor 13 and the grinding wheel 4.

  The lower contact sensor 14 is disposed at the lower end of the arm 11. The lower contact sensor 14 is a known contact sensor, and detects a contact between the lower contact sensor 14 and the wafer chuck 3.

  The control means 15 operates the measuring mechanism 10 in accordance with a program stored in advance. The control means 15 receives a detection signal emitted by the upper contact sensor 13 or a detection signal emitted by the lower contact sensor 14. The control means 15 is in a state in which the upper contact sensor 13 and the lower contact sensor 14 emit detection signals, that is, the upper contact sensor 13 contacts the grindstone 4 and the lower contact sensor 14 contacts the wafer chuck 3 The state is determined to be the grinding start position. The control means 15 sends position information on the grinding start position of the grinding wheel 4 to the grinding wheel feeder 4a.

  Next, a wafer grinding method will be described based on FIG. FIG. 4 is a flowchart showing a procedure of measuring the grinding start position of the grinding wheel.

  The wafer grinding method includes the step of measuring the grinding start position (zero point position) of the grinding wheel 4 using the measuring mechanism 10 as shown in FIG. 4 in addition to the known steps. First, the arm 11 is disposed between the wafer chuck 3 and the grindstone 4 (S1). Specifically, the elevating means 12 arranges the arm 11 between the wafer chuck 3 and the grindstone 4 in the vertical direction V. In addition, the air piston 12 a expands and contracts to slide the arm 11 in the horizontal direction H as necessary. These operations are optionally performed to place the contact point of the lower contact sensor 14 with the wafer chuck 3 and the contact point of the upper contact sensor 13 with the grinding wheel 4 at a desired position.

  Next, the arm 11 is lowered (S2) to bring the lower contact sensor 14 into contact with the wafer chuck 3 (S3). Specifically, the arm 11 is also lowered according to the lowering operation of the lifting means 12. When the lower contact sensor 14 detects the contact with the wafer chuck 3, the control means 15 stops the lowering operation of the lifting means 12, and the arm 11 stops.

  Next, the grindstone 4 is lowered (S4), and the upper contact sensor 13 is brought into contact with the grindstone 4 (S5). Specifically, when the grinding stone feeder 4a feeds the grinding stone 4 downward and the upper contact sensor 13 detects that the grinding wheel 4 contacts the grinding wheel 4, the control means 15 stops the feed operation of the grinding stone feeder 4a and the grinding stone 4 Stop.

  Then, the state in which the upper contact sensor 13 contacts the grindstone 4 and the lower contact sensor 14 contacts the wafer chuck 3 is set as the grinding start position (S6). That is, after the control means 15 receives a signal from the lower contact sensor 14 that detects contact with the wafer chuck 3, it receives a signal from the upper contact sensor 13 that detects contact from the lower surface to the grinding wheel 4. And the grindstone 4 face each other at an interval corresponding to the thickness of the arm 11, the lower contact sensor 14 and the upper contact sensor 13. Therefore, the distance between the wafer chuck 3 and the grinding wheel 4 is automatically measured. Note that the upper contact sensor 13 and the lower contact sensor 14 may either contact the non-contact object (the wafer chuck 3 or the grindstone 4) first before the lower contact sensor 14 and the wafer chuck 3 contact with each other. The upper contact sensor 13 and the grindstone 4 may be in contact with each other. Also, the lower contact sensor 14 is not an essential component in determining the grinding start position. It is also possible to replace the lower contact sensor 14 with an alternative means having the function of stopping the lowering operation of the lifting means 12. As an alternative means of the lower contact sensor 14, for example, an overload stopper for stopping the descent when the load of the motor-driven lifting means 12 reaches a predetermined value or more, a descent more than a predetermined amount of the cylinder-driven lifting means 12 The cylinder stopper etc. which can prevent can be considered.

  The wafer grinding method preferably includes the step of measuring the straightness of the grinding wheel 4. Thereby, it is confirmed before grinding that the grindstone 4 is attached horizontally, and it is suppressed that the grindstone 4 is inclined to the wafer W in the inclined state, so the entire surface of the grindstone 4 is uniformly applied to the wafer W In contact, a smooth grinding surface can be obtained. Here, “straightness of the grindstone” means that the surface of the grindstone 4 is perpendicular to the rotation axis of the grindstone 4.

  The measurement procedure of the straightness of the grindstone 4 will be described based on FIG. FIG. 5 is a flow chart showing a procedure of measuring the straightness of the grindstone 4. In the process of measuring the straightness of the grindstone 4, first, the arm 11 is disposed below the grindstone 4 (S11). Next, the arm 11 is raised to approach the grindstone 4 (S12). The arm 11 ascends until the upper contact sensor 13 and the grinding wheel 4 contact (S13).

  The upper contact sensor 13 measures the height of the contact point between the upper contact sensor 13 and the grindstone 4 (S14). The height of the contact point is derived based on, for example, the amount of feed of the lifting means 12 in the vertical direction V. When the height measurement of the contact point is completed, the arm 11 is slightly lowered (S15). Thereby, the contact between the upper contact sensor 13 and the grinding wheel 4 is released.

  Next, the control means 15 determines whether or not the height measurement of the touch points has been completed by the number of touch points set in advance (S16). If the number of measurement of the contact point is smaller than the number of measurement set in advance (No in S16), the grinding wheel 4 is rotated about the rotation axis (S17), and the height measurement of the other contact point is performed. By rotating the grinding wheel 4, the contact points are arranged concentrically on the grinding wheel 4.

  If the measurement number of the contact points has reached the preset measurement number and the height measurement is completed (Yes in S16), the straightness of the grindstone 4 is measured from the height of each measurement point (S18) . The measurement procedure of the straightness of the grinding wheel will be described later.

  Furthermore, the wafer grinding method preferably includes the step of measuring the straightness of the wafer chuck 3. Thereby, it is confirmed before grinding that the wafer chuck 3 is mounted horizontally, and since the wafer W is prevented from contacting the grindstone 4 in a tilted state, the grindstone 4 contacts the wafer W uniformly. And a smooth grinding surface can be obtained. Here, “straightness of the wafer chuck” means that the surface of the wafer chuck 3 is perpendicular to the rotation axis of the wafer chuck 3.

  The measurement procedure of the straightness of the wafer chuck 3 will be described based on FIG. FIG. 6 is a flowchart for measuring the straightness of the wafer chuck 3. In the process of measuring the straightness of the wafer chuck 3, first, the arm 11 is disposed above the wafer chuck 3 (S21). Next, the arm 11 is lowered to approach the wafer chuck 3 (S22). The arm 11 is lowered until the lower contact sensor 14 and the wafer chuck 4 contact (S23).

  The lower contact sensor 14 measures the height of the contact point between the lower contact sensor 14 and the wafer chuck 3 (S24). The height of the contact point is derived based on, for example, the amount of feed of the lifting means 12 in the vertical direction V. When the height measurement of the contact point is completed, the arm 11 is slightly raised (S25). Thereby, the contact between the lower contact sensor 14 and the wafer chuck 3 is released.

  Next, the control means 15 determines whether or not the height measurement of the touch points has been completed by the number of touch points set in advance (S26). If the number of measurement of the contact point is smaller than the number of measurement set in advance (No in S26), the wafer chuck 3 is rotated about the rotation axis (S27), and the height measurement of the other contact point is performed. By rotating the wafer chuck 3, the contact points are arranged concentrically on the wafer chuck 3.

  If the measurement number of the contact points has reached the preset measurement number and the height measurement is completed (Yes in S26), the straightness of the wafer chuck 3 is measured from the height of each measurement point (S28) ). The measurement procedure of the straightness of the wafer chuck 3 will be described later.

  The measurement of the straightness of the grindstone 4 and the straightness of the wafer chuck 3 will be described based on FIGS. In addition, since the measurement procedure of the straightness of the grindstone 4 and the measurement procedure of the straightness of the grindstone 4 are the same, only the measurement procedure of the straightness of the grindstone 4 will be described here, and the measurement procedure of the straightness of the wafer chuck 4 I omit the explanation about. FIG. 7 is a schematic view showing the measurement points of the grindstone 4, and FIG. 8 (a) is a view showing the height of each measurement point when the straightness can not be secured, and FIG. 8 (b) is a view 3 is a diagram showing the height of each measurement point when the straightness is secured.

  As shown in FIG. 7, when four points (A to D) concentrically spaced at equal intervals on the grindstone 4 are used as the contact points, as shown in FIG. When the dispersion occurs, the straightness of the grindstone 4 is not ensured. The reason why the straightness of the grindstone 4 can not be ensured is, for example, that foreign matter intervenes between the grindstone 4 and the flange to which the grindstone 4 is attached, and it is considered that the grindstone 4 is attached obliquely to the flange Be Therefore, when foreign matter intervenes between the grindstone 4 and the flange, it is necessary to once remove the grindstone 4 from the flange to remove the foreign matter. Therefore, by removing the foreign matter from the flange 4 by removing the grindstone 4, as shown in FIG. 8 (b), the straightness of the grindstone 4 is secured by making the height of each contact point (A to D) the same. Be done.

  Thus, the invention according to the above-described embodiment can automatically measure the distance between the wafer chuck 3 and the grindstone 4, so that the positioning of the grinding start position of the grindstone 4 can be easily performed. In addition, since the grinding start position of the grinding wheel 4 can be measured simply by providing the measuring mechanism 10 in the existing wafer grinding apparatus, economical cost can be reduced. Furthermore, since the alignment of the grindstone 4 is performed in a state in which the lower contact sensor 14 contacts the wafer chuck 3, grinding of the grindstone 4 is performed even if the height of the wafer chuck 3 is changed before and after replacement of the wafer chuck 3. The starting position can be accurately obtained.

  Further, the upper contact sensor 13 measures the heights of the plurality of contact points of the grindstone 4, and the control means 15 measures the straightness of the grindstone 4 from the heights of the plurality of contact points measured by the upper contact sensor 13. Thus, it is confirmed before grinding that the grindstone 4 is mounted horizontally, so that the wafer W is prevented from being partially hit while the grindstone 4 is inclined, and the entire surface of the grindstone 4 is uniformly applied to the wafer W In contact, a smooth grinding surface can be obtained.

  Also, the lower contact sensor 14 measures the heights of the plurality of contact points of the wafer chuck 3, and the control means 15 determines the straightness of the wafer chuck 3 from the heights of the plurality of contact points measured by the lower contact sensor 14. By measuring, it is confirmed before grinding that the wafer chuck 3 is mounted horizontally, contact with the grindstone 4 in a state where the wafer W is inclined is suppressed, and the grindstone 4 contacts the wafer uniformly. , Smooth ground surface can be obtained.

  The present invention can be modified in various ways without departing from the spirit of the present invention, and it goes without saying that the present invention extends to those modified as well.

DESCRIPTION OF SYMBOLS 1 · · · Wafer grinding apparatus 2 · · · INDEX table 2a · · · Partition wall 3 · · · Wafer chuck 4 · · · Grinding stone 4a · · · Grinding stone feeding device 5 · · · Polishing cloth (polish pad)
6 ··· First rack 7 ··· Second rack 8 ··· First arm 9 ··· Second arm 10 ··· Measuring mechanism 11 ··· Arm 11a ··· (Arms ) Base end 12 ··· Lifting means 12a · · · Air piston 13 · · · Upper contact sensor 14 · · · Lower contact sensor 15 · · · Control means W · · · Wafer H · · · Horizontal direction V · · · · Vertical direction

The present invention has been proposed to achieve the above object, and the invention according to claim 1 is a wafer grinding apparatus for grinding a wafer by pressing a grindstone against the surface of a wafer placed on a wafer chuck, determines the height sensor for measuring the height of a plurality of contact points of the previous SL grindstone, whether from said height grindstone of the plurality of points of said height sensor is measured is attached horizontally, said grinding wheel If it is determined that the wheel is not mounted horizontally, the wheel is reinstalled, and if it is determined that the wheel is mounted horizontally, the height sensor contacts the wheel A wafer grinding apparatus is provided, comprising: control means for judging that the wheel is in the grinding start position of the grinding wheel.

The wafer grinding apparatus according to the present invention is a wafer that presses a grindstone against the surface of a wafer mounted on a wafer chuck to grind the wafer, in order to achieve the purpose of aligning the grinding start position smoothly and easily. in the grinding device, determining a height sensor for measuring the heights of the plurality of contact points of the previous SL grindstone, whether from said height grindstone of the plurality of points of said height sensor is measured is attached horizontally If it is determined that the whetstone is not attached horizontally, the whetstone is reattached, and if it is determined that the whetstone is attached horizontally, the height sensor indicates the whetstone. Control means for determining the state of contact with the grinding start position of the grinding wheel.

Claims (1)

In a wafer grinding apparatus for grinding a wafer by pressing a grinding stone against the surface of a wafer placed on a wafer chuck,
An arm horizontally extended between the wafer chuck and the grinding wheel;
Raising and lowering means for vertically raising and lowering the arm;
An upper contact sensor disposed on the upper surface of the arm to detect contact of the grinding wheel;
A control unit that determines a state in which the upper contact sensor is in contact with the grindstone as a grinding start position of the grindstone;
A wafer grinding apparatus comprising: