JP2007059938A - Method for polishing wafer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a CMP device which makes the amount of polishing uniform among simultaneously polished wafers, and supplies polishing slurry appropriately to the wafers even when a flow rate of supplied polishing slurry is large. <P>SOLUTION: This CMP device is provided with a surface plate 10 rotationally driven around a first rotation shaft Ax1; a polishing pad 11 attached to the surface plate 10; two sets of carriers 20, 20 which are rotationally driven around second rotation shafts Ax2, Ax2 eccentric from the first rotation shaft Ax1, and hold the wafers 12, 12 to press them on the polishing pad 11, respectively; a supply nozzle 30 which supplies the polishing slurry 13 onto the polishing pad 11; and an adjustment mechanism 40 which adjusts a tip position of the supply nozzle 30 relative to the polishing pad 11. By suitably moving a tip of the supply nozzle 30 according to the amount of the supplied polishing slurry, and positions of the wafers, etc., the supply position of the polishing slurry is adjusted. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a polishing method in a manufacturing process of a semiconductor device and a polishing apparatus used in the method, and more particularly to a chemical mechanical polishing (CMP) apparatus.

  15 and 16 show a state of polishing using a conventional CMP apparatus, FIG. 15 is a side view, and FIG. 16 is a plan view. The main part of the CMP apparatus includes two sets of carriers 2a and 2b that hold and rotate the wafers 1a and 1b, respectively, and a rotatable surface plate 4 with a polishing pad 3 fixed on the upper surface. The carriers 2 a and 2 b are rotated while pressing the wafers 1 a and 1 b against the polishing pad 3. Further, the CMP apparatus is provided with a supply nozzle 6 for supplying an abrasive (slurry) 5 onto the polishing pad 3.

  During polishing, pressure is applied while rotating the carriers 2a and 2b to press the wafers 1a and 1b against the polishing pad 3, and the surface plate 4 is rotated. At the same time, the polishing slurry 5 is supplied from the supply nozzle 6 onto the polishing pad 3. As a result, the surfaces of the wafers 1a and 1b are planarized by being chemically and mechanically polished by the polishing pad 3 and the polishing slurry 5.

  However, in the conventional CMP apparatus described above, since the supply nozzle 6 is fixed at one place, the polishing slurry 5 does not spread uniformly on the polishing pad 3, and the polishing amount of the wafer becomes non-uniform. There's a problem. For example, as shown in FIG. 16, when the surface plate 4 rotates counterclockwise, the carrier 2a side located upstream in the rotation direction with respect to the supply position of the polishing slurry 5 is larger than the other carrier 2b side. Thus, the polishing amount of the wafer 1a held on the carrier 2a is larger than the polishing amount of the wafer 1b held on the other carrier 2b.

  Further, the supply amount (flow rate) of polishing slurry per hour varies depending on the process of the wafer to be polished, but when the flow rate is relatively large, the flow rate of the polishing slurry discharged from the supply nozzle 6 becomes large, and polishing is performed. There is a problem that the slurry jumps on the polishing pad 3 and jumps out of the polishing pad 3 without being supplied to the wafer.

  The present invention has been made in view of the above-described problems of the prior art. When a plurality of wafers are polished simultaneously, the polishing amount between the wafers can be made uniform and supplied. It is an object (object) to provide a CMP apparatus capable of appropriately supplying a polishing slurry to a wafer even when the flow rate is large.

  Accordingly, the present invention has been made in view of the above matters, that is, the present invention is a method for polishing a wafer, and a surface plate that is driven to rotate about a first rotation axis, A fixed polishing pad, a supply nozzle that supplies a polishing slurry that is inclined with respect to the polishing pad and has a tip disposed above the polishing pad, and a second rotation axis that is eccentric from the first rotation axis And a carrier that holds the wafer and presses it against the polishing pad, and when the flow rate of the polishing slurry is increased, the tip of the supply nozzle is moved backward from the supply nozzle. The polishing slurry is supplied onto a polishing pad.

  In the wafer polishing method of the present invention, the supply nozzle may be configured such that the tip can be slide-adjusted independently of each other with respect to the orthogonal biaxial method.

  Further, in the wafer polishing method of the present invention, the tip of the supply nozzle may be moved according to the flow rate so that the supply position of the polishing slurry on the polishing pad is kept constant regardless of the flow rate. Good.

  According to the present invention, a carrier that is rotationally driven around a second rotational axis that is eccentric from the first rotational axis is mounted on a polishing pad that is attached to a surface plate that is rotationally driven around a first rotational axis. The method includes a step of pressing the wafer and driving the surface plate and the carrier to polish the wafer, and a step of supplying a polishing slurry onto the polishing pad while moving the nozzle.

  Further, the tip of the nozzle in the present invention may have a shape bent downward.

  Furthermore, it is good also as a structure by which several supply holes are formed in the front-end | tip of the nozzle in this invention.

  Further, the present invention is rotationally driven around a second rotational axis that is eccentric from the first rotational axis on a polishing pad that is affixed on a surface plate that is rotationally driven around the first rotational axis. The wafer is pressed by a carrier, the surface plate and the carrier are driven to polish the wafer, the polishing slurry is supplied to a slurry pool provided in the rotating shaft portion, and the slurry pool is transferred to the polishing pad. And a method for polishing a wafer including a step of discharging a polishing slurry.

  In addition, the slurry reservoir in the present invention is a hole provided in the polishing pad, and it is preferable that the polishing slurry is supplied from the hole to the polishing pad.

  The slurry reservoir in the present invention may be a hole provided in the polishing pad and the surface plate, and the polishing slurry may be supplied from the hole to the polishing pad.

  Furthermore, the slurry reservoir in the present invention is a container provided in the first rotating shaft portion, and the polishing slurry can be supplied from the container to the polishing pad.

  The chemical mechanical polishing apparatus according to the present invention includes a surface plate driven to rotate about the first rotation axis, a polishing pad affixed on the surface plate, and a first plate eccentric from the first rotation axis. 2 is rotated around the rotation axis of 2 to hold the wafer and press it against the polishing pad; a supply nozzle that supplies polishing slurry onto the polishing pad; and a tip position of the supply nozzle that is adjusted relative to the polishing pad And an adjusting mechanism.

  By comprising as mentioned above, the front-end | tip of a supply nozzle can be moved suitably, the supply position of polishing slurry can be adjusted, and polishing slurry can be spread uniformly on a polishing pad. The supply nozzle can be configured to discharge polishing slurry in multiple directions from the tip. At this time, it is desirable that the adjustment mechanism be able to adjust the vertical position of the tip of the supply nozzle.

The chemical mechanical polishing apparatus according to the present invention includes a surface plate driven to rotate about the first rotation axis, a polishing pad affixed on the surface plate, and a first decentered from the first rotation axis. 2 is driven to rotate around the rotation axis 2 and holds the wafer and presses it against the polishing pad; a supply nozzle that supplies polishing slurry onto the polishing pad; and a central portion of the polishing pad that is discharged from the supply nozzle And a slurry reservoir for storing the polishing slurry once and then releasing it to the surroundings.

  The slurry pool is constituted by a single hole formed in the polishing pad, or a first hole formed in the polishing pad and a second hole formed in the surface plate so as to communicate therewith, or the polishing pad Configured as a container. When the slurry reservoir is constituted by a container, a hole for accommodating a part of the container is formed in the polishing pad or the polishing pad and the surface plate, and the part of the container is inserted into the hole and disposed. May be.

  As described above, according to the CMP apparatus of the present invention, the polishing slurry is provided by appropriately moving the tip of the supply nozzle by providing the adjustment mechanism that adjusts the tip position of the supply nozzle relative to the polishing pad. Can be adjusted, and the polishing slurry can be spread uniformly on the polishing pad.

  According to the present invention, according to the configuration of claim 2, the polishing slurry can be discharged in multiple directions from the tip of the supply nozzle, and the difference in the flow rate of the polishing slurry is within the range in which the polishing slurry is dispersed. In order to cope with the size of the nozzle, the adjustment mechanism can change the range of the dispersion range if the vertical position of the tip of the supply nozzle can be adjusted.

  Further, according to the CMP apparatus of the present invention, the polishing slurry flow rate is increased because the slurry reservoir for temporarily storing the polishing slurry discharged from the supply nozzle and then discharging it to the surroundings is arranged at the center of the polishing pad. However, there is no rebound on the surface of the polishing pad, and the polishing slurry can be supplied uniformly over the entire surface of the polishing pad.

  When a single hole formed in the polishing pad is used as a slurry pool, it can be handled by processing only the polishing pad, which is a consumable item, so that most of the conventional apparatus can be used.

  Further, when the slurry reservoir is constituted by the first hole formed in the polishing pad and the second hole formed in the surface plate so as to communicate with the first hole, the depth of the slurry reservoir can be increased. Therefore, even when the flow rate of the polishing slurry discharged from the supply nozzle is large, the polishing slurry can be prevented from jumping up, and the uniformity of the supply of the polishing slurry can be further improved.

  When a container placed on a polishing pad is used as a slurry reservoir, there is no need to process the polishing pad or surface plate, and the installation position of the container can be arbitrarily selected according to the flow rate of the polishing slurry. The degree is high, and it can cope with more kinds of CMP processes.

  In addition, when a part of the container is inserted into the polishing pad or inserted into the hole formed with the polishing pad and the surface plate, the depth of the slurry reservoir is set to be larger than that when the hole is directly used as a slurry reservoir. It is possible to increase the depth, and to effectively prevent jumping when the flow rate of the polishing slurry is large.

  Hereinafter, three embodiments of the chemical mechanical polishing (CMP) apparatus according to the present invention will be described.

FIG. 1 is a side view showing the main part of the CMP apparatus according to the first embodiment, and FIG. 2 is a plan view. The main part of the CMP apparatus includes a surface plate 10 that is driven to rotate about a first rotation axis Ax1, a polishing pad 11 that is affixed on the surface plate 10, and a second that is eccentric from the first rotation axis Ax1. Two sets of carriers 20 and 20 that are driven to rotate about the rotation axis Ax2 and press the wafers 12 and 12 against the polishing pad 11, respectively, a supply nozzle 30 that supplies the polishing slurry 13 onto the polishing pad 11, and a supply And an adjustment mechanism 40 for adjusting the tip position of the nozzle relative to the polishing pad 11.

  A backing plate 21 is fixed at the center of the carrier 20 as shown in an enlarged view in FIG. 3, and this backing plate 21 has a protruding portion equal to the outer diameter of the wafer 12. A backing film 22 is affixed.

  The wafer 12 is fastened together with the backing plate 21 by a clamp ring 24 via a retainer ring 23 while being in close contact with the backing film 22. That is, the retainer ring 23 is disposed so as to surround the outer periphery of the protrusion of the backing plate 21 and the wafer 12, and the clamp ring 24 has a function of fixing the retainer ring 23 from the outside.

  The backing plate 21 is a rigid body such as ceramic, and its lower surface has extremely high flatness. The backing film 22 is an elastic body such as polyurethane foam, and has a function of maintaining the uniformity of polishing by maintaining high adhesion of the wafer 12 and absorbing / dispersing an impact during polishing.

  In this example, the adjustment mechanism 40 has a configuration in which the tip position of the supply nozzle 30 can be slide-adjusted independently of each other with respect to the two orthogonal axes. That is, as shown in an enlarged view in FIG. 4, the adjusting mechanism 40 includes two fixed rails 41 and 41 arranged in parallel to each other, and the extending direction of the fixed rail 41 between the fixed rails. The movable frame 42 is slidable along x, and the holding member 43 is attached to the movable frame 42 so as to be slidable in a direction y orthogonal to the sliding direction of the fixed frame 42. The tip of the supply nozzle 30 is fixed through substantially the center of the holding member 43, and the slide position of the slurry on the polishing pad 11 is adjusted by sliding the moving frame 42 and the holding member 43. Can be adjusted arbitrarily.

  According to the first embodiment, the tip of the supply nozzle 30 is appropriately moved according to the supply amount of the polishing slurry, the position of the wafer, and the like to adjust the supply position of the polishing slurry, so that the polishing slurry is placed on the polishing pad 11. Therefore, it is possible to reduce both the dispersion of the polishing amount in a single wafer and the imbalance of the polishing rate among a plurality of wafers.

  For example, when the supply amount (flow rate) of polishing slurry per time is relatively large, the supply position of the polishing slurry on the polishing pad 11 is set by retracting the tip of the supply nozzle 30 as compared with the case where the flow rate is low. It can be kept constant regardless of the flow rate.

  FIG. 5 shows a first modification of the first embodiment. In this example, a supply nozzle 31 in which only the tip portion is bent downward is used. The supply nozzle 31 of FIG. 5 is also attached to the adjustment mechanism 40 similar to the above-described embodiment. However, when the supply nozzle 31 of FIG. 5 is used, the slurry supply position can be kept constant even when the flow rate of the polishing slurry is changed. Therefore, the linear supply nozzle 30 of the first embodiment In comparison, the need to adjust the nozzle position is reduced.

FIG. 6 shows a second modification of the first embodiment. In this example, a supply nozzle 32 in which a plurality of supply holes 32a are formed so as to discharge polishing slurry in multiple directions is used. Since the supply nozzle 32 disperses and discharges the polishing slurry in multiple directions, the difference in the flow rate of the polishing slurry corresponds to the size of the range in which the polishing slurry is dispersed, and the center of the dispersion range hardly changes. Therefore, in this case, if the vertical position of the tip of the supply nozzle 32 can be adjusted as the adjustment mechanism, the range of the dispersion range can be changed. However, also in the modified example of FIG. 6, the position of the supply nozzle 32 may be adjusted by an adjustment mechanism that can be driven in two directions as in the first embodiment. In this case, the positional accuracy of the supply nozzle 32 with respect to the polishing pad 11 is relaxed, and the adjusting means can be controlled with lower accuracy than in the first embodiment.

FIG. 7 is a sectional view showing the main part of the CMP apparatus according to the second embodiment, and FIG. 8 is a plan view thereof. The CMP apparatus of the second embodiment is decentered from the surface plate 10 that is driven to rotate about the first rotation axis Ax1, the polishing pad 11 that is affixed on the surface plate 10, and the first rotation axis Ax1. Two sets of carriers 20 and 20 which are rotationally driven around the second rotation axes Ax2 and Ax2 to hold the wafers 12 and 12 and press the wafers 12 and 12 respectively, and a supply nozzle which supplies the polishing slurry 13 onto the polishing pad 11 30 and a slurry reservoir 50 which is disposed in the center of the polishing pad 11 and temporarily stores the polishing slurry discharged from the supply nozzle 30 and then discharges it to the surroundings. In this example, the slurry reservoir 50 is formed as a hole 11a penetrating the polishing pad 11, and by attaching the perforated polishing pad 11 on the surface plate 10, the upper surface of the surface plate 10 is the bottom surface and the periphery of the hole 11a. A cylindrical container-like space having a side surface is formed, and this becomes a slurry reservoir 50.

  The configurations of the surface plate 10, the carrier 20, and the like are the same as those in the first embodiment, except that the slurry reservoir 50 is provided, the supply nozzle 30 is fixedly provided, and the adjustment mechanism 40 is not provided. Is different from the first embodiment.

  In the first embodiment, when the flow rate of the polishing slurry increases, the polishing slurry rebounds on the surface of the polishing pad 11, and it may be difficult to uniformly supply the polishing slurry to the entire surface of the polishing pad. In this respect, in the second embodiment, since the polishing slurry is stored in the slurry reservoir 50, even if the flow rate is increased, there is no rebound on the surface of the polishing pad 11, and the polishing slurry is uniformly supplied to the entire surface of the polishing pad. It becomes possible.

  According to the configuration of the second embodiment, the polishing slurry discharged from the supply nozzle 30 is temporarily stored in the slurry reservoir 50, and the amount supplied exceeding the capacity overflows from the slurry reservoir 50 and spreads around. The spread of the polishing slurry is uniform regardless of the direction of the supply nozzle 30, whereby the polishing slurry can be spread uniformly on the polishing pad 11, and the amount of polishing in a single wafer varies, and Both polishing rate imbalances among a plurality of wafers can be kept small.

  Since the polishing pad 11 is a consumable item and is replaced as needed, the capacity of the slurry reservoir 50 can be easily changed by changing the size of the hole formed as necessary.

  FIG. 9 is a cross-sectional view showing a modification of the second embodiment. In the CMP apparatus of the modified example, a second hole 10a is also formed in the surface plate 10 so as to communicate with the first hole 11a formed in the polishing pad 11, and the first and second holes 11a and 10a are formed. Thus, a slurry reservoir 51 for storing the polishing slurry is formed. According to this configuration, since the depth of the slurry pool can be made deeper than in the second embodiment, even when the flow rate of the polishing slurry discharged from the supply nozzle 30 is large, the polishing slurry can be prevented from jumping up. The uniformity of the supply of the polishing slurry can be further improved.

In order to change the capacity of the slurry reservoir 51, the first and second holes 11a and 10a are used.
You can change the size of. However, the size of the first hole 11a formed in the polishing pad 11 can be changed by replacing the polishing pad 11, but the surface plate 10 cannot be replaced. 9 is used, the inner diameter of the hole 10a is increased stepwise by inserting a cylindrical filling member into the second hole 10a formed in the surface plate 10 as necessary. The volume of the polishing slurry stored in the slurry reservoir 51 is adjusted. 10 and 11 are a cross-sectional view and a plan view showing a state where the first and second filling members 60 and 61 are inserted into the second hole 10a. The first filling member 60 is a cylindrical member having an outer diameter substantially equal to the inner diameter of the hole 10 a and having a through hole formed at the center thereof. The second filling member 61 is a first filling member 60. This is a cylindrical member having an outer diameter that fits into the through hole and having a through hole formed in the center. When the filling member is not used, the capacity of the slurry reservoir 51 is the largest. When only the first filling member 60 is inserted, the capacity is minimum, and when the first and second filling members are both inserted, the capacity is minimum. It becomes capacity.

  FIG. 12 is a sectional view showing the main part of the CMP apparatus according to the third embodiment, and FIG. 13 is a plan view thereof. Similar to the apparatus of the second embodiment, the CMP apparatus of the third embodiment includes a surface plate 10, polishing pads 11, two sets of carriers 20, 20, a supply nozzle 30, and a slurry reservoir 52. In this example, the slurry reservoir 52 is configured as a bottomed cylindrical container 70 disposed on the polishing pad 11.

  The container 70 is attached to the upper surface of the polishing pad 11, and the polishing slurry discharged from the supply nozzle 30 is once stored in the container 70, and the amount supplied beyond the capacity overflows from the container 70 and spreads around. As in the second embodiment, the spread of the polishing slurry is uniform regardless of the direction of the supply nozzle 30, which allows the polishing slurry to be spread uniformly on the polishing pad 11, so that a single wafer can be spread. It is possible to reduce both the variation in the polishing amount and the polishing rate imbalance among a plurality of wafers. Further, it is not necessary to process the polishing pad 11 or the surface plate 10, and the installation position of the container 70 can be arbitrarily selected according to the flow rate of the polishing slurry. It can correspond to.

  FIG. 14 is a modified example of the above-described third embodiment, and is configured in combination with the modified example of the second embodiment shown in FIG. That is, the polishing pad 11 and the surface plate 10 are formed with first and second holes 11a and 10a communicating with each other, and a bottomed cylindrical container 71 higher than the depth of the hole is inserted into these holes. The slurry pool 53 is configured by being fixed. According to this configuration, the depth of the slurry pool can be increased and the jumping up when the polishing slurry has a large flow rate can be more effectively prevented than when the holes 11a and 10a are directly used as the slurry pool.

The side view which shows the principal part of the CMP apparatus of 1st Embodiment. The top view of the CMP apparatus shown in FIG. The expanded sectional view of the carrier part of the CMP apparatus shown in FIG. The enlarged view of the adjustment mechanism part of the CMP apparatus shown in FIG. The side view which shows the principal part of the CMP apparatus concerning the 1st modification of 1st Embodiment. The side view of the supply nozzle which shows the 2nd modification of 1st Embodiment. Sectional drawing which shows the principal part of the CMP apparatus of 2nd Embodiment. FIG. 8 is a plan view of the CMP apparatus shown in FIG. 7. Sectional drawing which shows the modification of 2nd Embodiment. Sectional drawing of the surface plate part of the CMP apparatus shown in FIG. The top view of the surface plate part of the CMP apparatus shown in FIG. Sectional drawing which shows the principal part of the CMP apparatus concerning 3rd Embodiment. FIG. 13 is a plan view of the CMP apparatus shown in FIG. 12. Sectional drawing of the CMP apparatus which shows the modification of 3rd Embodiment. The side view which shows the principal part of the conventional CMP apparatus. FIG. 16 is a plan view of the CMP apparatus shown in FIG. 15.

Explanation of symbols

10 Surface plate 11 Polishing pad 12 Wafer 20 Carrier 30, 31, 32 Supply nozzle 40 Adjustment mechanism 50 Slurry pool 70 Container

Claims (3)

A surface plate driven to rotate about the first rotation axis;
A polishing pad fixed on the surface plate;
A supply nozzle for supplying a polishing slurry that is inclined with respect to the polishing pad and has a tip disposed above the polishing pad;
Using a polishing apparatus comprising: a carrier that is rotationally driven around a second rotation axis that is eccentric from the first rotation axis, and that holds a wafer and presses the wafer against the polishing pad;
A polishing method for a wafer, wherein when the flow rate of the polishing slurry increases, the tip of the supply nozzle is retracted and the polishing slurry is supplied from the supply nozzle onto the polishing pad.   2. The wafer polishing method according to claim 1, wherein the supply nozzle has a tip that can be slidably adjusted independently of each other with respect to the orthogonal biaxial method.   2. The wafer polishing method according to claim 1, wherein the tip of the supply nozzle is moved according to the flow rate so that the supply position of the polishing slurry on the polishing pad is kept constant regardless of the flow rate. Wafer polishing method.

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