JP7079871B2 - Grinding device - Google Patents

Description

The present invention relates to a grinding device, and more particularly to a grinding device provided with a dressing means for dressing a grinding wheel.

In the field of semiconductor manufacturing, backside grinding is performed to grind the back side of a wafer in order to form a semiconductor wafer such as a silicon wafer (hereinafter referred to as “wafer”) as a thin film.

As a grinding device for grinding the back surface of a wafer, Patent Document 1 discloses a device including a holding means for holding the wafer, a grinding wheel for grinding the wafer, and a dress member for dressing the grinding wheel. ..

In such a grinding device, when the dress member is pressed against the grinding wheel, the abrasive grains of the grinding wheel are separated and a spontaneous blade is generated. Since the dress member is pressed in parallel with the grinding wheel, the grinding surface of the grinding wheel is dressed so as to be leveled horizontally. Then, the wafer can be ground into a flat shape by pressing a grinding wheel having a flat grinding surface against the wafer. As a result, even with a difficult-to-cut material such as sapphire, the wafer can be continuously ground without causing surface burn of the wafer due to wear of the abrasive grains of the grinding wheel.

Japanese Patent No. 5815150

However, in the grinding apparatus described in Patent Document 1 as described above, since the grinding surface of the grinding wheel is dressed flat, when the thickness of the wafer varies, the thickness of the grinding wheel is made uniform. There is a problem that it is difficult to locally change the grinding amount, for example, to grind a wafer into a medium-convex shape in which the central portion of the wafer is thicker than the outer peripheral portion or a middle-concave shape in which the central portion of the wafer is thinner than the outer peripheral portion. ..

Therefore, there arises a technical problem to be solved, which is to dress the grinding surface of the grinding wheel into a curved shape according to a desired wafer shape, and an object of the present invention is to solve this problem.

The present invention has been proposed in order to achieve the above object, and the invention according to claim 1 includes a holding means for holding a wafer and a grinding means having a grinding wheel for grinding the wafer. A dressing means for dressing the grinding wheel, a dressing means tilting mechanism capable of tilting the dressing means with respect to the rotation axis of the grinding wheel, and a control means for adjusting the tilt angle of the dressing means tilting mechanism. The dressing means tilting mechanism is vertically stretchable and includes a first movable support portion that tilts a first tilt table on which the dressing means is placed, and the holding means is said to have the above-mentioned holding means. The holding means tilting mechanism capable of tilting the wafer with respect to the rotation axis of the grinding wheel is provided, and the holding means tilting mechanism is arranged at a position symmetrical to the first movable support portion with the grinding wheel sandwiched in a plan view. Provided is a grinding apparatus provided with a second movable support portion which is vertically expandable and can tilt a second tilt table on which a chuck for holding the wafer is placed.

According to this configuration, by pressing the dressing means against the grinding wheel with the dressing means tilted with respect to the rotation axis of the grinding wheel, the grinding surface of the grinding wheel is dressed in a curved shape according to a desired wafer shape. be able to.

Further, the grinding wheel is tilted so that the inclination of the dressing means with respect to the rotation axis (tilt angle of the dressing means) matches the inclination of the holding means with respect to the rotation axis of the grinding wheel (tilt angle of the holding means). By dressing the ground surface, the angle at which the dressing means hits the grinding wheel and the angle at which the wafer hits the grinding wheel match, so that the desired shape of the wafer after grinding can be indirectly defined according to the inclination of the dressing means. can.

Further, the first movable support portion and the second movable support portion arranged symmetrically with each other across the grinding wheel move up and down correspondingly, so that the angle at which the dressing means hits the grinding wheel is the angle at which the wafer hits the grinding wheel. Since it can be easily set to match the above, the desired shape of the ground wafer can be indirectly defined according to the inclination of the dressing means.

In the present invention, the dressing means is pressed against the grinding wheel in a state where the dressing means is tilted with respect to the rotation axis of the grinding wheel, so that the ground surface of the grinding wheel is dressed in a curved shape according to a desired wafer shape after grinding. can do.

The side view which shows the grinding apparatus which concerns on one Embodiment of this invention. The plan view of the grinding apparatus shown in FIG. FIG. 2 is a partially cutaway side view of the line I-I showing the internal structure of the wafer chuck. Top view showing the dress unit. FIG. 4 is a partially cutaway side view of the line II-II of FIG. 4, showing the internal structure of the dress unit and the dress unit tilting mechanism. The schematic diagram which shows the state of dressing a grinding wheel with a dress unit. The schematic diagram which shows the state which the dress unit is tilted according to the tilt angle of a wafer chuck.

The grinding device according to the present invention has a holding means for holding the wafer and a grinding wheel for grinding the wafer in order to achieve the object of dressing the grinding surface of the grinding wheel in a curved shape according to a desired wafer shape. A grinding device provided with a grinding means, the dressing means for dressing the grinding wheel, the dressing means tilting mechanism capable of tilting the dressing means with respect to the rotation axis of the grinding wheel, and the tilt angle of the dressing means tilting mechanism. The dressing means tilting mechanism is vertically telescopic and comprises a first movable support for tilting the first tilt table on which the dressing means is mounted, the holding means comprising: adjusting means. The holding means tilting mechanism capable of tilting the wafer with respect to the rotation axis of the grinding wheel is provided, and the holding means tilting mechanism is arranged at a position symmetrical to the first movable support portion across the grinding wheel in a plan view and is in the vertical direction. This is realized by providing a second movable support portion that is flexible and allows the second tilt table on which the chuck for holding the wafer is placed to be tilted.

Hereinafter, the grinding apparatus 1 according to an embodiment of the present invention will be described with reference to the drawings. In the following examples, when the number, numerical value, quantity, range, etc. of the components are referred to, the specific number is used unless it is explicitly stated or the principle is clearly limited to a specific number. It is not limited, and may be more than or less than a specific number.

In addition, when referring to the shape and positional relationship of components, etc., unless otherwise specified or when it is considered that it is not clearly the case in principle, those that are substantially similar to or similar to the shape, etc. are used. include.

In addition, the drawings may be exaggerated by enlarging the characteristic parts in order to make the features easy to understand, and the dimensional ratios of the constituent elements are not always the same as the actual ones. Further, in the cross-sectional view, hatching of some components may be omitted in order to make the cross-sectional structure of the components easy to understand. In this embodiment, the terms "upper" and "lower" correspond to upper and lower in the vertical direction.

FIG. 1 is a side view showing a basic configuration of a grinding apparatus 1 in which a dress unit 8 is omitted. FIG. 2 is a plan view of the grinding device 1. FIG. 3 is a partially cutaway side view of FIG. 2 showing the wafer chuck 3. FIG. 4 is a plan view showing the dress unit 8. FIG. 5 is a partially cutaway side view of the line II-II of FIG. 4, showing the internal structure of the dress unit 8 and the dress unit tilting mechanism 9.

The grinding device 1 grinds the wafer W on the back surface by the grinding means 2 to form a thin film. The grinding means 2 includes a grinding wheel 21, a spindle 22 having the grinding wheel 21 attached to the tip thereof, and a spindle feeding mechanism 23 for feeding the spindle 22 in the vertical direction V.

The grinding wheel 21 is horizontally attached to the tip of the spindle 22. The wafer W is ground by pressing the grinding wheel 21 against the wafer W.

The spindle 22 rotates the grinding wheel 21 along the rotation direction C1 about the rotation axis a1 by a motor (not shown).

The spindle feed mechanism 23 includes two linear guides 23a for connecting the column 4 and the spindle 22, and a known ball screw slider mechanism (not shown) for moving the spindle 22 up and down in the vertical direction V.

A wafer chuck 3 as a holding means is arranged below the grinding means 2. In order to continuously grind a plurality of wafers W, the grinding apparatus 1 includes a plurality of wafer chucks 3. The plurality of wafer chucks 3 are arranged at predetermined intervals on the circumference around the rotation axis of the index table 5.

The wafer chuck 3 includes a chuck 31 and an air bearing 32.

An adsorbent (not shown) made of a porous material such as alumina is embedded in the upper surface of the chuck 31. The wafer chuck 3 includes a conduit (not shown) that passes through the chuck 31 and the air bearing 32 and extends to the surface of the chuck 31. The pipeline is connected to a vacuum source, a compressed air source and a water supply source (not shown) via a rotary joint (not shown) connected to the rotor 32a of the air bearing 32. When the vacuum source is activated, the wafer W placed on the chuck 31 is attracted and held by the chuck 31. Further, when the compressed air source or the water supply source is activated, the adsorption between the wafer W and the chuck 31 is released.

The air bearing 32 includes a rotor 32a that can rotate around the rotation shaft a2, and a stator 32b that is arranged on the outer periphery of the rotor 32a. The rotor 32a and the chuck 31 are fixed by bolts (not shown). The rotor 32a is connected to the rotary joint and rotates the chuck 31 about the rotation axis a2 along the rotation direction C2. A predetermined gap (air gap) is provided between the rotor 32a and the stator 32b, and by supplying compressed air to this gap from the outside, the rotor 32a rotates in a non-contact manner with respect to the stator 32b. be able to.

The wafer chuck 3 includes a chuck tilting mechanism 6 that tilts the rotary shaft a2 with respect to the rotary shaft a1 of the grinding wheel 21. The chuck tilting mechanism 6 includes a tilt table 61, a fixed support portion 62, an upstream side movable support portion 63, and a downstream side movable support portion 64.

The tilt table 61 is formed in a substantially triangular shape in a plan view. On the tilt table 61, the fixed support portion 62, the upstream side movable support portion 63, and the downstream side movable support portion 64 are arranged 120 degrees apart on the circumference of the radius R1 with the rotation axis a2 as the center.

The fixed support portion 62 is fastened to the tilt table 61 with bolts 62a.

The upstream movable support portion 63 is arranged on the upstream side of the wafer chuck 3 in the rotation direction C2 with respect to the fixed support portion 62. Since the structure of the upstream movable support portion 63 is the same as that of the downstream movable support portion 64, the structure will be described by taking the downstream side movable support portion 64 as an example, and the description of the upstream side movable support portion 63 will be omitted. ..

The downstream movable support portion 64 is arranged on the downstream side of the wafer chuck 3 in the rotation direction C2 with respect to the fixed support portion 62. The downstream movable support portion 64 has a nut 64a embedded in the tilt table 61, a tilt ball screw 64b fixed to the index table 5 and whose upper portion is screwed to the nut 64a, and a tilt motor for rotating the tilt ball screw 64b. It is equipped with 64c. The downstream movable support portion 64 is formed longer than the fixed support portion 62 in the vertical direction V.

The grinding device 1 includes a scale 7 for measuring the amount of sedimentation of the tilt table 61 due to the load when the grinding means 2 presses the wafer W.

The grinding device 1 includes a dress unit 8 for dressing the grinding wheel 21. The dress unit 8 includes a dress board 81, a dress base mechanism 82, and a dress unit feed mechanism 83.

The dress board 81 includes a dress material 81a that is arranged so as to face the grinding wheel 21 and dresses the grinding wheel 21, and a dress base 81b that supports the dress material 81a. The dress material 81a is a material having a higher altitude than the grinding wheel 21, and is formed of, for example, white alumina and a binder.

The dress base mechanism 82 rotatably supports the dress board 81. Specifically, the dress base mechanism 82 includes a rotor 82a that can rotate around the rotation axis a3, a stator 82b arranged on the outer periphery of the rotor 82a, and a base member 82c that is connected to the rotor 82a to support the dressboard 81. And have.

The rotor 82a is connected to a rotary joint (not shown), and rotates the dress board 81 and the base member 82c around the rotation axis a3 along the rotation direction C3. A predetermined gap (air gap) is provided between the rotor 82a and the stator 82b, and by supplying compressed air to this gap from the outside, the rotor 82a rotates in a non-contact manner with respect to the stator 82b. be able to.

Further, the dress base mechanism 82 includes a conduit (not shown) extending through the rotor 82a to the surface of the base member 82c. The pipeline is connected to a vacuum source and a compressed air source (not shown) via a rotary joint connected to the rotor 82a. When the vacuum source is activated, the dress board 81 placed on the base member 82c is adsorbed and held by the base member 82c. Further, when the compressed air source is activated, the adsorption between the dress board 81 and the base member 82c is released.

The dress unit feed mechanism 83 includes two linear guides 83a connected to a base table 95, which will be described later, and a known ball screw slider mechanism 83b for raising and lowering the base table 95 in the vertical direction V. That is, the linear guide 83a and the ball screw slider mechanism 83b are arranged in parallel with the spindle feed mechanism 23.

Further, the dress unit 8 includes a touch sensor 84 for measuring the thickness of the dress material 81a. The touch sensor 84 is provided so as to be able to swing around the turning center 84a.

Further, the dress unit 8 is provided with a nozzle 85 for supplying coolant water to the surface of the dress material 81a. A flare type capable of sprinkling coolant water over a wide range may be adopted for the nozzle 85, and the nozzle 85 may be configured to be applied to the grinding wheel 21 and the touch sensor 84.

The dress unit 8 includes a dress unit tilting mechanism 9 that tilts the rotating shaft a3 with respect to the rotating shaft a1 of the grinding wheel 21. The dress unit tilting mechanism 9 includes a tilt table 91, a fixed support portion 92, an upstream side movable support portion 93, and a downstream side movable support portion 94.

On the tilt table 91, the fixed support portion 92, the upstream side movable support portion 93, and the downstream side movable support portion 94 are arranged 120 degrees apart on the circumference of the radius R2 with the rotation axis a3 as the center.

The fixed support portion 92 is a bolt that connects the tilt table 91 and the base table 95 in the vertical direction V. Reference numeral 92a in FIG. 5 is a spherical washer interposed between the tilt table 91 and the base table 95.

The upstream movable support portion 93 is arranged on the upstream side of the dress board 81 in the rotation direction C3 with respect to the fixed support portion 92. The structure of the upstream movable support portion 93 is the same as that of the downstream movable support portion 94, and the description of the upstream movable support portion 93 will be omitted.

The downstream movable support portion 94 is arranged on the downstream side of the dress board 81 in the rotation direction C3 with respect to the fixed support portion 92. The downstream movable support portion 94 includes an adjustment knob 94a and a tilt ball screw 94b.

The adjustment knob 94a is formed in a cylindrical shape, and its tip is fitted to the tilt table 91. An insertion hole 94c is formed in the adjustment knob 94a.

The tilt ball screw 94b is inserted into the insertion hole 94c, and its tip is fitted to the base table 95. A spring 94d is interposed between the tilt ball screw 94a and the adjustment knob 94b. When the tilt ball screw 94b rotates, the tilt table 91 is configured to rise by the amount that the tilt ball screw 94b is screwed.

The operation of the grinding device 1 is controlled by the control device 10. The control device 10 controls each of the constituent elements constituting the grinding device 1. The control device 10 is composed of, for example, a CPU, a memory, and the like. The function of the control device 10 may be realized by controlling using software, or may be realized by operating using hardware.

In the control device 10, the rotating shaft a2 is tilted with respect to the rotating shaft a1 so that a desired wafer thickness can be obtained based on the thickness of the wafer W measured by the thickness sensor (not shown), and the grinding wheel 21 is used for the wafer W. Adjust the machining range to grind. The thickness sensor is not limited to the one included in the configuration of the grinding device 1, and may be, for example, one that feeds back the data measured by the external device of the grinding device 1 to the control device 10. The upstream movable support portion 63 and the downstream movable support portion 64 independently expand and contract along the vertical direction V, and the tilt table 61 is tilted with respect to the fixed support portion 62 to tilt the rotation axis a2. Can be done.

The control device 10 stores data on the amount of grinding of the wafer W according to the angle (tilt angle Θ1) of the rotating shaft a2 with respect to the rotating shaft a1, that is, the contact angle of the wafer W with respect to the grinding wheel 21. Thereby, the thickness of the wafer W before grinding or the thickness of the wafer W during grinding is measured, and the grinding amount and the tilt angle of the rotating shaft a2 with respect to the rotating shaft a1 are adjusted from the difference between this thickness and the thickness of the desired wafer. Further, data regarding the shape of the grinding surface 21a of the grinding wheel 21 according to the angle (tilt angle Θ2) of the rotating shaft a3 with respect to the rotating shaft a1 is stored.

Next, the operation of the dress unit 8 will be described with reference to the drawings. FIG. 6 is a schematic view showing a state in which the grinding wheel 21 is dressed by the dress unit 8. FIG. 7 is a schematic view showing a state in which the dress unit 8 is tilted according to the tilt angle of the wafer chuck 3.

The dress unit 8 dresses the grinding surface 21a of the grinding wheel 21 after grinding the wafer W. Specifically, when the grinding of the wafer W is completed, the grinding wheel 21 retracts above the vertical direction V. After that, the ball screw slider mechanism 83b is driven, and the dress material 81a approaches the grinding surface 21a of the grinding wheel 21.

Then, by pressing the dress board 81 toward the grinding wheel 21 while rotating the grinding wheel 21 and the dress board 81, the grinding surface 21a of the grinding wheel 21 is dressed by the dress material 81a.

Since the ball screw slider mechanism 83b is arranged in parallel with the spindle feed mechanism 23, the ball screw slider mechanism 83b receives a pressing force along the vertical direction V when the dressboard 81 is pressed against the grinding wheel 21. The grinding wheel 21 can be stably dressed.

Further, since the ball screw slider mechanism 83b is arranged between the center O of the grinding wheel 21 and the spindle feed mechanism 23, the dressboard is placed on the base table 95 cantilevered by the linear guide 83a and the ball screw slider mechanism 83b. When the pressing force along the vertical direction V when pressing the 81 against the grinding wheel 21 is suppressed, the base table 95 cantilevered and supported by the linear guide 83a dresses the grinding wheel 21. Since it is suppressed from jumping up due to the reaction force, the grinding wheel 21 can be dressed more stably.

When dressing the grinding wheel 21, coolant water is supplied to the surface of the dressing material 81a. When the dress board 81 rotates while the coolant water is being supplied, the excess coolant water is scattered by centrifugal force, and an extremely thin water film WF is formed on the surface of the dress material 81a. As an example of forming the water film WF, it is conceivable to set the supply amount of the coolant water to 0.1 to 0.5 l / min and the rotation speed of the dressboard 81 to 400 rpm or less. In this way, the touch sensor 84 comes into contact with the dress material 81a via the water film WF, so that the wear of the touch sensor 84 is suppressed. The coolant water is preferably supplied so as to hit the grinding wheel 21 and the touch sensor 84.

The rotating shaft a3 of the dress unit 8 can be tilted by the dress unit tilting mechanism 9 to dress the grinding surface 21a of the grinding wheel 21 into a curved surface. For example, as shown in FIG. 7, the dress board 81 is pushed against the grinding wheel 21 in a one-sided state by extending the upstream movable support portion 93 and the downstream movable support portion 94 and tilting the tilt table 91. It is possible to form the grinding surface 21a of the grinding wheel 21 so that the central portion of the grinding wheel 21 is thicker than the outer peripheral portion in a medium-convex shape. Further, the upstream movable support portion 93 and the downstream movable support portion 94 contract and the tilt table 91 tilts, so that the central portion of the grinding wheel 21 is formed into a concave shape thinner than the outer peripheral portion to form the grinding surface 21a of the grinding wheel 21. Can be formed.

When the wafer chuck 3 is tilted, the upstream movable support portion 93 and the downstream movable support portion 94 of the tilt table 91 so that the tilt angle Θ1 of the tilt table 61 and the tilt angle Θ2 of the tilt table 91 match. Stretch.

Specifically, the expansion / contraction amount ΔL1 of the upstream movable support portion 63 and the expansion / contraction amount ΔL2 of the downstream movable support portion 64 are measured on a scale (not shown). Of the upstream movable support portion 93 and the downstream movable support portion 94, one of the upstream movable support portions 93 is located symmetrically with the upstream movable support portion 63 with the center O of the grinding wheel 21 interposed therebetween (in this embodiment, the downstream side movable support portion). 94) is expanded and contracted by the expansion and contraction amount ΔL3 according to the expansion and contraction amount ΔL1. The expansion / contraction amount ΔL3 is calculated by ΔL3 = ΔL1 × R2 / R1.

Further, of the upstream movable support portion 93 and the downstream movable support portion 94, the other (in this embodiment, the upstream movable support portion) is located symmetrically with the downstream movable support portion 64 with the center O of the grinding wheel 21 interposed therebetween. 93) is expanded and contracted by the expansion and contraction amount ΔL4 according to the expansion and contraction amount ΔL2. The expansion / contraction amount ΔL4 is calculated by ΔL4 = ΔL2 × R2 / R1.

That is, by pre-dressing the grinding surface 21a of the grinding wheel 21 according to the inclination of the wafer chuck 3, the shape of the wafer W can be indirectly determined according to the inclination of the dress board 81.

In this way, the above-mentioned grinding apparatus 1 grinds the grinding wheel 21 according to the desired shape of the wafer W after grinding by pressing the dressing material 81a against the grinding wheel 21 in a state where the dress board 81 is tilted. The surface 21a can be dressed in a curved shape.

Further, by dressing the grinding surface 21a of the grinding wheel 21 in a state where the dress board 81 is tilted so as to match the tilt of the wafer chuck 3, the angle at which the dress board 81 hits the grinding wheel 21 and the wafer W are the grinding wheel 21. Since the angle corresponding to the above is the same, the desired shape of the ground wafer W can be indirectly defined according to the inclination of the dressboard 81.

It should be noted that the present invention can be modified in various ways as long as it does not deviate from the spirit of the present invention, and it is natural that the present invention extends to the modified ones.

1 ・ ・ ・ Grinding device 2 ・ ・ ・ Grinding means 21 ・ ・ ・ Grinding wheel 22 ・ ・ ・ Spindle 23 ・ ・ ・ Spindle feed mechanism 23a ・ ・ ・ Linear guide 3 ・ ・ ・ Wafer chuck (holding means)
31 ・ ・ ・ Chuck 32 ・ ・ ・ Air bearing 32a ・ ・ ・ Rotor 32b ・ ・ ・ Stator 4 ・ ・ ・ Column 5 ・ ・ ・ Index table 6 ・ ・ ・ Chuck tilt mechanism 61 ・ ・ ・ Tilt table 62 ・ ・ ・ Fixed Support part 62a ・ ・ ・ Bolt 63 ・ ・ ・ Upstream side movable support part 64 ・ ・ ・ Downstream side movable support part 7 ・ ・ ・ Scale 8 ・ ・ ・ Dress unit (dressing means)
81 ... Dress board 81a ... Dress material 81b ... Dress base 82 ... Dress base mechanism 82a ... Rotor 82b ... Stator 82c ... Base member 83 ... Dress unit feed mechanism 83a ・ ・ ・ Linear guide 83b ・ ・ ・ Ball screw slider mechanism 84 ・ ・ ・ Touch sensor 84a ・ ・ ・ Swivel center 85 ・ ・ ・ Nozzle 9 ・ ・ ・ Dress unit tilt mechanism 91 ・ ・ ・ Tilt table 92 ・ ・ ・ Fixed support Part 93 ・ ・ ・ Upstream side movable support part 94 ・ ・ ・ Downstream side movable support part 10 ・ ・ ・ Control device W ・ ・ ・ Wafer

Claims (1)

A grinding device including a holding means for holding a wafer and a grinding means having a grinding wheel for grinding the wafer.
The dressing means for dressing the grinding wheel and
A dressing means tilting mechanism capable of tilting the dressing means with respect to the rotation axis of the grinding wheel,
A control means for adjusting the tilt angle of the dress means tilt mechanism, and
Equipped with
The dressing means tilting mechanism is vertically stretchable and includes a first movable support that tilts a first tilt table on which the dressing means is placed.
The holding means includes a holding means tilting mechanism capable of tilting the wafer with respect to the rotation axis of the grinding wheel.
The holding means tilting mechanism is arranged at a position symmetrical to the first movable support portion with the grinding wheel sandwiched in a plan view, and is vertically expandable and expandable, and a second chuck for holding the wafer is placed. A grinding device comprising a second movable support for tilting the tilt table of the.

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