JP2005125444A - Dressing device of polishing pad - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent tearing-off of a pad of a central part since a dresser bites in the central part of the polishing pad when dressing the polishing pad used for a polishing device by the dresser. <P>SOLUTION: This dressing device 1 can change a rocking speed of a dresser grinding wheel 2 on the polishing pad 200, by changing a rotating speed of a rotary shaft 10 by tooth meshing driving of a worm gear 11b and a worm wheel 11c by driving of an AC servomotor 11a, by rotatably arranging a support arm 6 on the rotary shaft 10, by moving the support arm 6 for supporting a spindle 3 for vertically journaling the dresser grinding wheel 2 in the longitudinal direction (the y axis direction). The device prevents biting-in of the dresser grinding wheel, by restraining abrasion in the polishing pad central part, by changing the rocking speed of the dresser grinding wheel on the polishing pad, so as to shorten a stagnant time of the dresser grinding wheel in the central part of the polishing pad and the outer peripheral vicinity of the polishing pad. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a dressing apparatus that uniformly wears a polishing pad surface by dressing a polishing pad surface provided in a polishing apparatus for a substrate such as a semiconductor substrate, a glass substrate, a silicon bare wafer, or a ceramic substrate with a diamond dresser grindstone. .

  In order to wear the polishing pad surface used for substrate polishing and chemical mechanical polishing with a diamond dresser grindstone, there is a dressing device that swings the diamond dresser grindstone on the polishing pad surface from the center of the polishing pad to the vicinity of the periphery of the polishing pad. in use.

  In order to wear the polishing pad surface more uniformly with the diamond dresser grindstone, it has been proposed to change the rocking speed of the diamond dresser grindstone between the center (origin) of the polishing pad and the vicinity of the outer periphery of the polishing pad.

  For example, the rotation direction of the polishing pad and the rotation direction of the diamond dresser grindstone are the same direction, the polishing pad is rotated at a first rotation speed, the diamond dresser grindstone is rotated at a second rotation speed, and the rotation speed ratio between the two is set. When expressed as a ratio of the prime natural numbers m and n, the minimum slope multiple of m and n is adjusted to 10 or more, and the diamond dresser grindstone is back and forth within the range from the origin of the polishing pad to the outer periphery. When performing a single vibration (oscillation) operation of plus or minus 8 mm (in the y-axis direction) and polishing with the center of the single vibration operation being coincident with the starting point position of the single vibration operation, the position of the diamond dresser grindstone While checking with the dresser rocking speed adjusting device, if the diamond dresser grinding wheel is near the outer periphery of the polishing pad, increase the rocking speed to suppress the wear of the polishing pad. The diamond dresser grindstone is swung in the front-rear direction (y-axis direction) from the outer periphery, and if the diamond dresser grindstone is near the origin of the polishing pad, the rocking speed is slowed down to promote the wear of the polishing pad. A method of performing dressing so that the diamond dresser grindstone stays long has been proposed (for example, see Patent Document 1).

It has also been proposed to perform dressing without swinging the dresser by controlling the rotational speed of the polishing pad, the rotational speed of the diamond dresser grindstone, and the pressure of the diamond dresser grindstone applied to the polishing pad. Specifically, the rotation direction of the polishing pad and the rotation direction of the diamond dresser grindstone are the same direction, and the formula DRR _min <kxPxV <DRR _max
(However, DRR _min is the lower limit value of the cutting rate, DRR _max is the upper limit value of the cutting rate, k is a constant determined by experiment, P is the dressing pressure, and V is the relative dressing rate. Means for determining the range of the product of the dressing pressure and the relative dressing speed based on
Means for controlling the pressure applied to bring the diamond dresser grindstone closer to the polishing pad based on the dressing pressure set by the operator within the range of the product;
There has been proposed a dressing device including means for controlling the rotational speed of the polishing pad and the rotational speed of the diamond dresser grinding wheel based on the relative speed of the dressing set by the operator within the range of the product (for example, Patent Document 2). reference.).
JP 2000-761 A JP 2003-257913 A

  In the dressing method described in Patent Document 1, if the diamond dresser grindstone is near the center (origin) of the polishing pad, the rocking speed is slowed down to promote the wear of the polishing pad, and the diamond dresser grindstone at the center Since the dressing is performed so that the stagnation is long, the center (origin) part of the polishing pad is worn too much, and the diamond dresser grindstone is too bite at the center of the polishing pad, making it difficult to separate from the polishing pad, There is a fault that scavenges. Also, since the diamond dresser grindstone is swung back and forth in a straight line, in order to clean the dressing grindstone after dressing, the grindstone washing tank of the grindstone washing mechanism is placed outside the outer periphery of the polishing pad and the diamond dresser grindstone is moved forward and backward. It must be installed in the direction, increasing the footprint of the dressing device.

  The method of performing dressing by setting the conditions from the correlation between the product of the applied pressure and the cutting speed described in Patent Document 2 may be theoretically correct, but in reality, the substrate to be polished The cutting speed depends on conditions such as the type, pad diameter, pad material, diamond dresser grindstone diameter, etc., so it takes about two to three weeks for the operator to find the optimum dress condition. Further, Patent Document 2 does not describe anything about the cleaning mechanism of the diamond dresser grindstone. The present invention provides a dressing apparatus with a small footprint that can perform dressing without biting a diamond dresser grindstone at the center of a polishing pad.

  According to the first aspect of the present invention, a polishing pad, a diamond dresser grindstone affixed to the upper surface of a polishing surface plate that can be rotated in the horizontal direction, and the diamond dresser grindstone vertically Spindle bearing in the direction (z-axis direction), rotating mechanism of the spindle, elevating mechanism for raising and lowering the spindle in the vertical direction (z-axis direction) and pressing the diamond dresser against the polishing pad or away from the polishing pad, the rotation A support arm that supports the mechanism and the lifting mechanism, a linear movement mechanism that slides a slider that fixes the support arm on a linear guide extending in the front-rear direction (y-axis direction), and a linear guide of the linear movement mechanism And the position where the axis of the polishing pad and the diamond dresser grindstone are concentric is the origin of oscillation. Support for changing the rocking speed of the diamond dresser wheel on the polishing pad by changing the rotational speed of the rotating shaft by meshing the worm gear and worm wheel by driving the AC servo motor. The present invention provides a dressing device for a polishing pad, comprising: an arm turning swing mechanism.

  According to a second aspect of the present invention, the dressing device includes a center line of a support arm that passes through the center of the polishing pad and is parallel to the front-rear direction (y-axis direction), and an axis of a rotation shaft of the support arm swivel swing mechanism. A grinding wheel cleaning tank is fixed to the base at a position below the support arm at the standby position of the support arm that connects the core, and the spindle that supports the diamond dresser grinding wheel drives the linear movement mechanism. Is moved in the front-rear direction (y-axis direction) to be positioned on the grindstone washing tank, and then the spindle is lowered by an elevating mechanism so that the diamond dresser grindstone is immersed in the washing liquid stored in the grindstone washing tank. It is further provided with a grindstone cleaning mechanism for removing foreign matter adhering to the diamond dresser grindstone by the rotation of the grindstone.

  The diamond dresser grindstone (dresser) can be swung on the polishing pad not in a linear direction but with a trajectory like the amplitude of the pendulum of the watch, and the optimum rocking speed can be achieved at each dressing position. This is a dressing device capable of changing a plurality of stages up to 20 stages by driving a servo motor.

  Since the number of times s for changing the acceleration of the diamond dresser grinding wheel can be an integer of 6 to 20, the stagnation time at the location can be increased by increasing the rocking speed of the diamond dresser grinding wheel near the center of the polishing pad and the dresser grinding wheel standby position. Because it is short, the diamond dresser grindstone will not bite into the center of the polishing pad and damage the center of the polishing pad.

  The cleaning mechanism for cleaning the diamond dresser grindstone is located outside the outer periphery of the polishing pad and in the linear movement direction (the y-axis direction in the front-rear direction) of the slider of the support arm that supports the diamond dresser grindstone. It fits compactly and does not increase the footprint.

(Example)
Hereinafter, the present invention will be described in more detail with reference to the drawings.
1 is an overall view showing the dressing apparatus of the present invention, FIG. 2 is a plan view of the dressing apparatus of the present invention installed on the side of the polishing surface plate, and FIG. 3 is a right side view of the dressing apparatus of the present invention which is partially omitted. FIG. 4, FIG. 4 is a sectional view taken along the II cutting line in FIG. 2 showing the spindle rotating mechanism, lifting mechanism and support arm moving mechanism of the dressing apparatus, and FIG. 5 is the left side of the dressing apparatus shown in FIG. 6 is a front view of the support arm swivel swing mechanism, FIG. 7 is a left side view of the support arm swivel swing mechanism, and FIG. 8 is a cross-sectional view of the support arm swivel swing mechanism. FIG. 7 is a cross-sectional view taken along the line II-II in FIG. 6.

  1, 2, and 3, 100 is a base, 101 is a carriage, 200 is a polishing pad, 300 is a control panel, 2 is a diamond dresser grinding wheel (electrodeposited diamond disk), and 3 is a spindle The diamond dresser grindstone is supported in the vertical direction (z-axis direction). Reference numeral 4 denotes a spindle rotation mechanism, which includes a servo motor 4a, a rotation shaft 4b, and a pulley 4c. The spindle 3 bearing the diamond dresser grindstone 2 is rotated by 20 to 200 rpm in the horizontal direction by driving the servo motor 4a.

  Reference numeral 5 denotes a spindle lifting mechanism, an air cylinder 5a, an air supply pipe 5b, a filter regulator 5c and an electronic pressure switch 5d constituting a primary air pressure confirmation sensor, an electromagnetic valve 5e for raising and lowering a dressing grindstone, and an electropneumatic regulator. 5f, pressure gauge 5g, dressing grindstone rising end confirmation sensor 5h, contact point auto switch 5i, electronic pressure switch 5j, pressure gauge 5k, dressing grindstone rising end confirmation sensor 5l, contact point auto switch 5m. . When pressurized air is introduced into the upper part of the cylinder of the air cylinder 5a, the rod 5n descends and pushes down the frame 5p for fixing the spindle 3. When the compressed air is introduced into the lower part of the air cylinder 5a, the rod 5n rises and pushes up the frame 5p for fixing the spindle 3. The electropneumatic regulator 5f adjusts the magnitude of dressing pressure (0 to 0.49 Mpa) when the spindle 3 is lowered in the vertical direction (z-axis direction) and the diamond dresser grindstone 2 is pressed against the polishing pad 200. . A maximum moving amount of the dressing grindstone 2 of 50 mm is sufficient.

  Reference numeral 6 denotes a support (swing) arm that supports the rotating mechanism 4 and the lifting mechanism 5. Reference numeral 7 denotes a slider for fixing the support arm 6. A linear moving mechanism 8 slides the slider 7 on a linear guide 9 extending in the front-rear direction (y-axis direction). The linear moving mechanism 8 includes an air cylinder 8a, the slider 7, the linear guide 9, the air supply pipe 5b, the spindle front / rear solenoid valve 8b, the contact auto switch 8c, the dressing spindle backward end confirmation sensor 8e, and the dressing spindle advance. It consists of an end confirmation sensor 8f and a contact auto switch 8d.

  Reference numeral 10 denotes a rotation shaft, which supports the linear guide 9 of the linear movement mechanism 8. The rotary shaft 10 is driven by the AC servo motor 11a of the swivel rocking mechanism 11 with the position where the center (O) of the polishing pad 200 and the axis of the diamond dresser grindstone 2 are concentric as the rocking origin (O). It swings like a trajectory of the amplitude of the pendulum. The swing swing mechanism 11 includes an AC servo motor 11a, a worm gear 11b, a worm wheel 11c, a swing axis origin sensor 11d, a swing axis + side OT sensor 11e, and a swing axis-side OT sensor 11f. . In FIG. 2, the pivot axis origin is a swing origin position O in which the center of the polishing pad 200 affixed to the upper surface of the polishing surface plate that can rotate in the horizontal direction and the axis of the diamond dresser grindstone 2 are concentric. The swivel axis + side in FIG. 2 indicates the swivel arm of the diamond dresser grindstone 2 in the anteroposterior direction 6 ′ with respect to the xyz three-dimensional coordinates orthogonal with the center point of the polishing pad 200 as the origin O in the longitudinal direction of the drawing. This is the position of the axis (+ OT) of the spindle 3 shown.

  The swing swing mechanism 11 is driven by an AC servo motor 11a for oscillation with a 1/20 speed reducer, and the rotational speed of the rotary shaft 10 is engaged with the teeth of the worm gear 11b and the worm wheel 11c. Is changed, the rocking speed of the diamond dresser grindstone 2 on the polishing pad 200 is changed. The AC servo motor 11a has a rated output of 400 W, a rated rotational speed of 3000 rpm, and a maximum rotational speed of 4500 rpm.

  The worm speed reducer is 1/93, the total reduction ratio is 1/1860, the rotation speed of the AC servo motor 11a is 3000 rpm, the turning radius of the arm 6 is 990 mm, The peripheral speed when the AC servo motor 11a rotates at 3000 rpm is calculated to be 10032.80 mm / min, and the movement amount of the AC servo motor 11a at one rotation is calculated as 3.344 mm. When the AC servo motor 11a rotates at 2900 rpm, the fast feed speed can be 10000 mm / min, the feed speed range can be 100 to 5000 mm / min linear speed, and the speed can be 50 to 5000 mm / min. Thus, the feed rate when the AC servo motor 11a rotates at 29.9 rpm is calculated as 100 mm / min, and the feed rate when the AC servo motor 11a rotates at 1495.2 rpm is calculated as 5000 mm / min. The swing coordinate unit is 0.1 mm.

The dressing of the polishing pad 200 with the diamond dresser grindstone 2 is performed on a trajectory such as the amplitude of the pendulum on the polishing pad. At this time, the AC servo motor with a reduction gear is driven at an optimum swing speed at each dressing position between the origin O and the vicinity of the outer periphery of the polishing pad close to the standby position (+ OT) (point P shown in FIG. 2). Accelerate and decelerate. The number of stages to be accelerated and decelerated is defined as s stages, the swing speed at that time is αi, the diamond dresser grindstone at the standby position (+ OT) outside the outer periphery of the polishing pad 200 is raised, and the rotary shaft 10 is turned. Move to the center (origin O) of the polishing pad, then lower the diamond dresser grindstone and press against the polishing pad, changing the rocking speed during the distance from the center of the polishing pad to the dressing end point P of the polishing mud. Swing while. Oscillation speed is suddenly accelerated from the origin O in order to suppress the wear of the polishing pad, then peaked at the acceleration alpha ₁ and distance swung a little away 10~50mm from the origin of the polishing pad, then the polishing pad the swing speed in order to increase the wear reduction alpha ₂ and the dress end point of the polishing pad so while the oscillation speed α ₃ ~α _r-2 to pivot the diamond dresser grindstone arcuate pendulum increasing or decreasing acceleration several times The diamond dresser grindstone is swung to a distance of about 5 to 10 mm from P, and the rocking speed of the diamond dresser grindstone is used to suppress wear of the polishing pad from the position where the diamond dresser grindstone is near the dress end point P of the polishing pad. a stretch enhance alpha _r-1 swings to dress the end point P of be faster polishing pad the axis of the diamond dressing grinding stone, the axis of the diamond dresser grindstone There is decelerated so that the swing speed alpha _s is 0 mm / min when he reached the dress end point P of the polishing pad. However, if the axis of the diamond dresser grindstone reaches the dressing end point P of the polishing pad, the rotation direction of the rotating shaft of the AC servo motor is reversed. It is possible to move toward the origin of the polishing pad.

The rocking of the diamond dresser grindstone returning (returning) from the dressing end point PO of the polishing pad to the origin O of the polishing pad accelerates or decelerates the absolute value of the forward acceleration with a plus or minus sign opposite to that of the forward, The diamond dresser grindstone is swung and swung at rocking speeds α _s , α _s-1 , α _s-2 ,... Α ₃ , α ₂ , α ₁ , and the axis of the diamond dresser grindstone is set at the origin of the polishing pad. The reciprocal rocking can be performed by matching the core positions.

  Since the number of times s to change the acceleration of the diamond dresser grindstone can be an integer of 6 to 20, even if one of the rocking speeds is selected incorrectly, it can be easily supplemented by adjusting the other rocking speed. Each swing speed can be easily selected. Further, since the stagnation time of the diamond dresser grindstone at the polishing pad origin position is short, the diamond dresser grindstone does not bite into the center portion of the polishing pad and damage the center portion of the polishing pad.

  For example, when a diamond dresser grindstone having a diameter of 200 mm and a rotation speed of 50 rpm is used, and a polishing pad having a diameter of 1010 mm and a rotation speed of 400 rpm obtained by polishing a wafer is dressed under the condition of an oscillation width of 330 mm, the polishing pad origin O and the polishing pad The rocking speed of the diamond dresser grindstone at the dress end point P (70 mm from the outer periphery) is 0 mm / min, and the rocking distance from the polishing pad origin O position to the outer periphery of the polishing pad is 20 mm. Speed) 9000 mm / min, over 20 to 50 mm, swing speed (linear speed) 5000 mm / min, over 50 to 100 mm, swing speed (linear speed) 100 mm / min, over 100 to 150 mm, 1000 mm / min, Swing speed (linear speed) 3000mm from 150 to 250mm Min, until 270mm beyond the 250 rocking speed (linear velocity) 9000 mm / min, and rocking speed (linear speed) 0 mm / minute reaches the point P.

  The diamond dresser grindstone 2 is cleaned by the cleaning mechanism 12. As shown in FIGS. 1 to 3, the dressing apparatus 1 includes a grindstone cleaning mechanism 12 that cleans the diamond dresser grindstone 2. The grindstone cleaning mechanism 12 includes a cleaning tank 12a, a cleaning liquid supply pipe 12b, a cleaning liquid supply electromagnetic valve (this electromagnetic valve indirectly operates the air operation pipe 5b) 12c, an air operation valve 12d, and an opening / closing valve 12f. The grindstone cleaning tank 12 a includes a center line of the support arm 6 ′ located at the standby position (+ OT) parallel to the front-rear direction (y-axis direction) passing through the center O of the polishing pad 200, and the axis of the rotary shaft 10. Are fixed by a support 12g extended from the base 100 at a position below the support arm connecting the two.

  The control panel 300 includes an operation panel for inputting and setting the spindle rotation speed, the origin, the number of swings, the swing speed at each position, the dresser start position, the dressing completion position, the current position, and the dresser pressurizing force. A rocking coordinate display panel indicating the current value is provided.

  The diamond dresser grindstone 2 is moved in the front-rear direction (y-axis direction) by driving the air cylinder 8a of the linear movement mechanism 8 to be positioned on the grindstone washing tank 12a, and then the spindle 3 is lowered by the elevating mechanism 5 to bring the diamond The dresser grindstone 2 is immersed in a cleaning solution stored in the grindstone cleaning tank 12a, and foreign matter adhering to the diamond dresser grindstone is removed by rotation of the diamond dresser grindstone at 20 to 200 rpm.

  The dressing apparatus for the polishing pad according to the present invention can change the rocking speed of the dresser grindstone on the polishing pad in multiple stages, thereby shortening the stagnation time of the dresser grindstone at the center point and the vicinity of the outer periphery of the polishing pad. This reduces the degree of wear of the polishing pad and facilitates the movement of the dresser grindstone on the polishing pad, so that the phenomenon that the dresser grindstone that occurs in the conventional dressing does not bite into the polishing pad and does not leave does not occur. . Further, since the swing of the dresser grindstone is the trajectory of the pendulum of the watch, and the cleaning mechanism of the dresser grindstone is provided outside the polishing pad on the extension of the trajectory of the pendulum, the dressing apparatus can be made compact.

It is a general view which shows the dressing apparatus of this invention. It is a top view of the dressing apparatus of this invention installed beside the polishing surface plate. It is a right view which lacked a part of dressing device of the present invention. It is sectional drawing cut | disconnected by the II cutting | disconnection line in FIG. 2 which shows the spindle rotating mechanism of the dressing apparatus, a raising / lowering mechanism, and a support arm moving mechanism. It is a left view of the dressing apparatus shown by FIG. It is a front view of a support arm turning rocking mechanism. It is a left view of a support arm turning rocking mechanism. It is sectional drawing of a support arm turning rocking | fluctuation mechanism, and is sectional drawing cut | disconnected by the II-II cutting line in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Dressing apparatus 100 Base 200 Polishing pad O Origin 300 Control board 2 Diamond dresser grindstone 3 Spindle 4 Spindle rotation mechanism 5 Spindle raising / lowering mechanism 6 Support (turning) arm 8 Linear movement mechanism 9 Ball bearing 10 Rotating shaft 11 Turning rocking Motion mechanism 11a AC servo motor 11b Worm gear 11b
11c Worm Wheel 12 Grinding Wheel Cleaning Mechanism

Claims (2)

  A polishing pad, a diamond dresser grindstone affixed to the upper surface of a polishing surface plate that can be rotated in the horizontal direction, and the diamond dresser grindstone in a vertical direction (z-axis direction) with respect to xyz three-dimensional coordinates perpendicular to the center of the polishing pad A spindle for bearing, a rotating mechanism for the spindle, and a lifting mechanism that lifts and lowers the spindle in the vertical direction (z-axis direction) and presses the diamond dresser against the polishing pad or moves away from the polishing pad, and supports the rotating mechanism and the lifting mechanism. A support arm, a linear movement mechanism that slides a slider that fixes the support arm on a linear guide extending in the front-rear direction (y-axis direction), a rotary shaft that supports the linear guide of the linear movement mechanism, and AC servo motor with the position where the axis of the polishing pad and the diamond dresser wheel are concentric as the origin of oscillation A support arm swivel swing mechanism that changes the swing speed of the diamond dresser grinding wheel on the polishing pad by changing the rotational speed of the rotating shaft by meshing the teeth of the worm gear and the worm wheel by driving. And a polishing pad dressing device.   The dressing apparatus includes a support arm that connects a center line of a support arm that passes through the center of the polishing pad and is parallel to the front-rear direction (y-axis direction) and the axis of the rotation shaft of the support arm swivel swing mechanism. A grinding wheel washing tank is fixed to the base at a position below the support arm at the stand-by position of the drum, and the spindle that supports the diamond dresser grinding wheel is driven by a linear movement mechanism in the front-rear direction (y-axis direction). ), And is positioned on the grindstone cleaning tank, and then the spindle shaft is lowered by the lifting mechanism to immerse the diamond dresser grindstone in the cleaning liquid stored in the grindstone washing tank, and the diamond dresser grindstone rotates to rotate the diamond dresser 2. The dressing device for a polishing pad according to claim 1, further comprising a grindstone cleaning mechanism for removing foreign matter adhering to the grindstone.

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