JP2015191930A - Chemical mechanical polishing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a CMP device which effectively jets a liquid to a polishing pad thereby improving the cleaning effect of the polishing pad.SOLUTION: A chemical mechanical polishing device includes: a table holding a polishing pad; a wafer holding part which holds a wafer so that the polishing pad contacts with the wafer; a liquid supply part which includes a first nozzle and a second nozzle, jets first liquid flow from the first nozzle, and jets second liquid flow from the second nozzle; and a rotation mechanism which rotates the polishing pad relative to the wafer holding part, the first nozzle, and the second nozzle. The first nozzle and the second nozzle are disposed so that the first liquid flow and the second liquid flow partially overlap with each other when viewed along a rotation direction of the polishing pad.

Description

  The present invention relates to a chemical mechanical polishing apparatus.

  In a semiconductor device manufacturing process, a technique for flattening the surface is important. If the planarization is insufficient and the unevenness of the surface of the semiconductor device becomes large, there is a possibility that a part of the thin film formed on the semiconductor device becomes thin or a disconnection portion of the wiring occurs. Further, if the planarization is insufficient, the exposure optical system may not be partially focused in the lithography process, and it may be difficult to form a fine pattern. In recent years, semiconductor devices have been further miniaturized, the element structure has become complicated, the number of layers of multilayer wiring has increased, and the importance of techniques for flattening the surface has increased.

  As a typical planarization technique, chemical mechanical polishing (CMP) is known. 2. Description of the Related Art In a chemical mechanical polishing apparatus (CMP apparatus) that performs chemical mechanical polishing, a polishing pad is rotated and a semiconductor wafer is pressed against the surface of the polishing pad while supplying a slurry containing abrasive grains to the surface of the polishing pad.

  Patent Document 1 below discloses that a CMP apparatus is provided with a liquid supply line and a liquid supply spray separately from the slurry supply line. In Patent Document 1, after polishing of a wafer is completed, a liquid is supplied from a liquid supply line or a liquid supply spray to clean the polishing pad.

JP 2005-31127 A

  However, in Patent Document 1 described above, the liquid supply line only hangs the liquid in one place, and the cleaning effect of the polishing pad is insufficient. In Patent Document 1, the liquid supply spray diffuses the liquid in a conical shape, but there is a portion where the liquid is not sprayed, and the cleaning effect of the polishing pad is still insufficient.

  The present invention has been made in view of the above technical problems. Some aspects of the present invention relate to improving the cleaning effect of a polishing pad by effectively ejecting liquid toward the polishing pad in a CMP apparatus.

In some embodiments of the present invention, a chemical mechanical polishing apparatus includes a table that holds a polishing pad, a wafer holding unit that holds a wafer so that the polishing pad and the wafer are in contact, and a first nozzle and a second nozzle. A liquid supply unit for ejecting the first liquid flow from the first nozzle and a second liquid flow from the second nozzle, and a polishing pad relative to the wafer holding unit, the first nozzle and the second nozzle. A rotating mechanism for rotating the chemical mechanical polishing apparatus, wherein the first nozzle and the second liquid flow partially overlap when viewed along the rotation direction of the polishing pad. A second nozzle is arranged.
According to this aspect, the first nozzle and the second nozzle are arranged so that the first liquid flow and the second liquid flow partially overlap when viewed along the rotation direction of the polishing pad. Cleaning the polishing pad by suppressing the occurrence of a portion where the liquid flow is not jetted between the first liquid flow and the second liquid flow due to the rotation of the polishing pad and the jetting of the first liquid flow and the second liquid flow. The effect can be improved.

In the above-described embodiment, the first cross section of the first liquid flow at the position reaching the polishing pad and the second cross section of the second liquid flow at the position reaching the polishing pad are dimensions along the rotation direction of the polishing pad, respectively. It is desirable that the first nozzle and the second nozzle be configured so that the dimension along the direction away from the rotation axis of the polishing pad is larger than that.
According to this, the liquid flow can be applied to the polishing pad over a wide range along the direction away from the rotation axis of the polishing pad. Further, in the direction along the rotation direction of the polishing pad, it is possible to suppress the dispersion of the liquid flow and to apply a strong liquid flow to the polishing pad.

In the above-described aspect, the first nozzle and the second nozzle are disposed such that the first cross section is located closer to the rotation axis of the polishing pad than the second cross section, and the first cross section is the second cross section. It is preferable that the first nozzle and the second nozzle are arranged so as to be located upstream of the rotation direction of the polishing pad.
According to this, it is suppressed that the solid substance discharge | released to a polishing pad moves to the downstream of the rotation direction of a polishing pad rather than a liquid flow.

In the above-described aspect, the first nozzle or the second nozzle has the directional component toward the upstream side in the rotation direction of the polishing pad so that the first nozzle or the second nozzle reaches the polishing pad. It is desirable to be disposed obliquely with respect to the rotation axis.
According to this, since the relative speed of the liquid flow with respect to the surface of the polishing pad is increased, a strong liquid flow can be applied to the polishing pad. Further, the solid material peeled off from the surface of the polishing pad by the liquid flow can be efficiently flowed toward the outer periphery of the polishing pad.

In the above-described aspect, the central axis of the first liquid flow or the second liquid flow has an inclination of 5 ° or more and 50 ° or less toward the upstream side in the rotation direction of the polishing pad with respect to the rotation axis of the polishing pad. In addition, it is desirable to arrange the first nozzle or the second nozzle.
According to this, since the relative speed of the liquid flow with respect to the surface of the polishing pad is increased, a strong liquid flow can be applied to the polishing pad. Further, the solid material peeled off from the surface of the polishing pad by the liquid flow can be efficiently flowed toward the outer periphery of the polishing pad.

In the above-described aspect, a conditioner for conditioning the polishing pad is further provided, and the first nozzle and the second nozzle are disposed on the upstream side in the rotation direction of the polishing pad with respect to the wafer holding portion, and the conditioner is disposed further on the upstream side. It is desirable that
According to this, it is suppressed that the solid substance dropped from the conditioner or other components reaches the wafer holder and damages the wafer.

1 is a perspective view conceptually showing the structure of a CMP apparatus according to an embodiment of the present invention. The perspective view which looked at the CMP apparatus shown by FIG. 1 from another angle. FIG. 2 is a plan view of the CMP apparatus shown in FIG. 1. The top view which shows the dimension of the cross section of the liquid flow in the arrival position to a polishing pad.

  Hereinafter, embodiments of the present invention will be described in detail. In addition, this embodiment demonstrated below does not unduly limit the content of this invention described in the claim. Also, not all of the configurations described in the present embodiment are essential as a solution means of the present invention. The same constituent elements are denoted by the same reference numerals, and description thereof is omitted.

<1. Overall configuration>
FIG. 1 is a perspective view conceptually showing the structure of a CMP apparatus according to an embodiment of the present invention. 2 is a perspective view of the CMP apparatus shown in FIG. 1 as seen from another angle, and FIG. 3 is a plan view. The CMP apparatus 100 includes a table 1, a wafer holding unit 2, and a conditioner 4.
A disc-shaped polishing pad 7 is attached to the upper surface of the table 1. The table 1 is rotated in the arrow A1 direction by the rotation mechanism 5.

  The wafer holding unit 2 holds the semiconductor wafer 3 and presses it against the polishing pad 7 with the surface of the wafer 3 to be polished, that is, the surface on which the semiconductor device is formed facing down. Wafer holder 2 is rotated in the direction of arrow A2 by a driving unit (not shown). At the same time, the wafer holding unit 2 may be reciprocated between a position near the center of the polishing pad 7 and a position near the edge of the polishing pad 7 in the radial direction of the polishing pad 7 by a driving unit (not shown). Good.

  The conditioner 4 includes a diamond abrasive layer and is pressed against the polishing pad 7 with the diamond abrasive layer facing downward. The conditioner 4 is rotated in the direction of arrow A4 by a drive unit (not shown). At the same time, the conditioner 4 may be reciprocated between a position near the center of the polishing pad 7 and a position near the edge of the polishing pad 7 in the radial direction of the polishing pad 7 by a driving unit (not shown). With such a configuration and operation, the conditioner 4 conditions the polishing pad 7. Conditioning includes cutting out the polishing pad 7 to restore the predetermined surface roughness required for the polishing pad 7.

  A slurry (suspension) containing abrasive grains is dropped on the surface of the polishing pad 7 from a slurry supply unit (not shown). This slurry also contains an acidic or alkaline chemical material for chemically modifying the wafer surface. The slurry dropped on the surface of the polishing pad 7 is stretched to the surface of the polishing pad 7 by the rotation of the table 1, the rotation of the wafer holder 2, and the rotation of the conditioner 4.

  When the polishing pad 7 has a predetermined surface roughness, the surface of the polishing pad 7 has a minute groove or a minute recess for holding the slurry. In the CMP apparatus 100, the wafer is polished by mechanical polishing with abrasive grains contained in the slurry and chemical action by chemical materials contained in the slurry.

  In the process of processing the wafer 3 with the above configuration, the solvent of the slurry may evaporate and aggregates may accumulate in the grooves or recesses on the surface of the polishing pad 7. Further, when a foreign substance is placed on the surface of the polishing pad 7, the foreign substance may be carried to the wafer holding unit 2. If foreign matter enters between the polishing pad 7 and the wafer 3, numerous scratches are formed on the wafer 3. Examples of the foreign matter include aggregates derived from the slurry, a part of the damaged part of the wafer holding unit 2, and abrasive grains dropped from the diamond abrasive layer of the conditioner 4.

<2. Liquid supply unit>
In the present embodiment, a liquid supply unit 6 that ejects a liquid flow toward the polishing pad 7 is provided. The liquid supply unit 6 includes a nozzle head 60 and a plurality of nozzles 61, 62, 63, and 64 arranged along the nozzle head 60. The nozzle 61 is disposed at a position close to the rotation axis C of the polishing pad 7, and the nozzles 62, 63 and 64 are disposed in this order in a direction away from the rotation axis C of the polishing pad 7. Two of the plurality of nozzles 61, 62, 63 and 64 correspond to the first nozzle and the second nozzle of the present invention.

  The nozzle head 60 distributes and supplies the liquid supplied from the pipe 65 to the plurality of nozzles 61, 62, 63 and 64. The plurality of nozzles 61, 62, 63, and 64 eject liquid streams 61a, 62a, 63a, and 64a, respectively. Of the liquid flows 61a, 62a, 63a and 64a, the liquid flow ejected from the first nozzle corresponds to the first liquid flow of the present invention, and the liquid flow ejected from the second nozzle corresponds to the second liquid flow of the present invention. To do. As the liquid, for example, pure water, a surfactant, or a combination thereof is used.

  FIG. 4 is a plan view showing the cross-sectional dimensions of the liquid flow at the position reaching the polishing pad 7. The liquid flows 61a, 62a, 63a, and 64a all have a flat flow path. Then, the cross-sections 61b, 62b, 63b and 64b of the liquid flows 61a, 62a, 63a and 64a at the position reaching the polishing pad 7 have dimensions 61W, 62W, 63W and 64W along the rotation direction A1 of the polishing pad 7, respectively. Rather, the dimensions 61L, 62L, 63L, and 64L along the direction away from the rotation axis C of the polishing pad 7 are larger.

As a result, the liquid flows 61a, 62a, 63a and 64a of the liquid can be applied over a wide range of the polishing pad 7. Further, it is possible to suppress the dispersion of the liquid flow along the rotation direction A1 of the polishing pad 7 and to apply strong liquid flows 61a, 62a, 63a and 64a to the polishing pad 7. The pressure of the liquid flow 61a, 62a, 63a and 64a when hitting the polishing pad 7 is preferably 1.0 kg / cm ² or more and 3.0 kg / cm ² or less. Of the cross sections 61b, 62b, 63b and 64b, the cross section of the first liquid flow corresponds to the first cross section of the present invention, and the cross section of the second liquid flow corresponds to the second cross section of the present invention.

  As shown in FIG. 1, the nozzles 61, 62, 63 and 64 are liquids adjacent to each other among the plurality of liquid flows 61 a, 62 a, 63 a and 64 a when viewed along the rotation direction A <b> 1 of the polishing pad 7. The streams are arranged so that they partially overlap each other. For example, the liquid flows 61 a and 62 a partially overlap when viewed along the rotation direction A <b> 1 of the polishing pad 7. Since the polishing pad 7 rotates in this state, it is possible to suppress occurrence of a portion where no liquid flow is jetted onto the polishing pad 7. In addition, since the polishing pad 7 is cleaned by two adjacent liquid flows among the liquid flows 61a, 62a, 63a, and 64a, the cleaning effect is improved. As shown in FIG. 1, the liquid flows 61 a, 62 a, 63 a, and 64 a have a shape that spreads from the upper side to the lower side at an angle ψ when viewed along the rotation direction A <b> 1 of the polishing pad 7. . The angle ψ is preferably 90 ° or more and 120 ° or less.

  In FIG. 2, a straight line V parallel to the rotation axis of the polishing pad 7 is shown. As shown in FIG. 2, the nozzles 61, 62, and 64 a, the liquid flows 61 a, 62 a, 63 a, and 64 a have a direction component opposite to the rotational direction A 1 of the polishing pad 7 and reach the polishing pad 7. It is desirable that 63 and 64 be arranged obliquely with respect to the straight line V. More specifically, the central axis F of the liquid flows 61a, 62a, 63a and 64a desirably has an inclination θ of 5 ° or more and 50 ° or less toward the upstream side in the rotation direction A1 of the polishing pad 7. More preferably, the inclination θ is 15 ° or more and 50 ° or less. The preferable numerical value of the inclination θ was obtained from the result of the cleaning evaluation described later.

  [Cleaning Evaluation] The influence of the inclination θ of the central axis F of the liquid flow 61a, 62a, 63a and 64a on the rotation axis of the polishing pad 7 on the cleaning was evaluated. After the solid material was rubbed into the polishing pad 7, the rotation speed of the polishing pad 7 necessary for removing the solid material was evaluated by applying a liquid flow of pure water while rotating the polishing pad 7. As a result, when θ = 0 °, it was 5 to 6 rotations, whereas when θ = 5 to 15 °, solids could be removed with 2 to 3 rotations, which greatly improved the cleaning efficiency. Improved. When θ = 15 to 50 °, the cleaning efficiency was further improved to 1 to 2 rotations. When θ exceeds 50 °, there is a problem that the removed solid matter is scattered around the CMP apparatus 100.

  Thus, when the liquid flows 61a, 62a, 63a and 64a have a direction component in the direction opposite to the rotation direction A1 of the polishing pad 7, the relative speeds of the liquid flows 61a, 62a, 63a and 64a with respect to the surface of the polishing pad 7 Therefore, strong liquid flows 61a, 62a, 63a and 64a can be applied to the polishing pad 7.

  Further, when the liquid flows 61a, 62a, 63a, and 64a have a direction component opposite to the rotation direction A1 of the polishing pad 7, the liquid that has reached the polishing pad 7 is pushed out upstream of the rotation direction A1 of the polishing pad 7. It is easy. Then, this liquid flows out toward the outer periphery of the polishing pad 7 along the upstream side of the cross sections 61b, 62b, 63b and 64b, as indicated by arrows E1 to E4 in FIGS. Thus, since the flow as shown by arrows E1 to E4 is formed, the solids peeled off from the surface of the polishing pad 7 by the liquid flows 61a, 62a, 63a and 64a are efficiently directed toward the outer periphery of the polishing pad 7. Flows out.

  Of the cross-sections 61b, 62b, 63b and 64b of the liquid flows 61a, 62a, 63a and 64a at the position reaching the polishing pad 7, the rotation axis is larger than the cross-section of the liquid flow located far from the rotation axis C of the polishing pad 7. The cross section of the liquid flow located near C is located upstream of the rotation direction A1 of the polishing pad 7. For example, the cross section 61b of the liquid flow 61a is positioned closer to the rotation axis C of the polishing pad 7 than the cross section 62b of the liquid flow 62a, and the cross section 61b is upstream of the cross section 62b in the rotational direction A1 of the polishing pad 7. To position.

  Thereby, for example, the solid material peeled off from the surface of the polishing pad 7 by the liquid flow 61a moves according to the flow of the arrow E1 along the cross section 61b. The solid material that has flowed to the vicinity of the end of the cross section 61b tries to move along the rotation direction A1 of the polishing pad 7, but the movement of the polishing pad 7 along the rotation direction A1 is stopped by the liquid flow 62a, and the cross section 62b It moves according to the flow of the arrow E2 along. Similarly, since it moves to the outer peripheral side of the polishing pad 7 in the order of the arrow E3 and the arrow E4, the solid matter moves downstream of the liquid flow 61a, 62a, 63a and 64a in the rotational direction A1 of the polishing pad 7. It is suppressed. The cross section 64b of the liquid flow 64a may extend over the outer periphery of the polishing pad 7 and the outer periphery of the polishing pad 7.

  The liquid supply unit 6 is desirably arranged on the upstream side of the rotation direction A1 of the polishing pad 7 relative to the wafer holding unit 2. It is desirable that the conditioner 4 is disposed further upstream than the liquid supply unit 6. Thereby, it is suppressed that the solid substance dropped from the conditioner 4 or other components reaches the wafer holder 2 and damages the wafer 3.

  The CMP apparatus 100 according to the present embodiment cleans the polishing pad 7 by the liquid supply unit 6 after the polishing of the wafer 3 held by the wafer holding unit 2 is finished and before the polishing of the next wafer is started. It may be what performs. Further, the polishing pad 7 may be cleaned by the liquid supply unit 6 while the wafer 3 is being polished.

  According to the present embodiment, the cleaning effect of the polishing pad 7 can be improved by effectively ejecting the liquid toward the polishing pad 7. As a result, the processing quality of the wafer 3 can be stabilized, and the quality of the semiconductor device can be improved.

  DESCRIPTION OF SYMBOLS 1 ... Table, 2 ... Wafer holding part, 3 ... Wafer, 4 ... Conditioner, 5 ... Rotation mechanism, 6 ... Liquid supply part, 7 ... Polishing pad, 60 ... Nozzle head, 61-64 ... Nozzle, 61a-64a ... Liquid Flow, 61b to 64b ... cross section, 61W, 62W, 63W, 64W ... dimension of liquid flow cross section along the rotation direction of the polishing pad, 61L, 62L, 63L, 64L ... along the direction away from the rotation axis of the polishing pad Dimensions of cross section of liquid flow, 65 ... pipe, 100 ... device, C ... rotation axis, F ... center axis.

Claims (6)

A table for holding a polishing pad;
A wafer holder for holding the wafer so that the polishing pad and the wafer are in contact with each other;
A liquid supply unit that includes a first nozzle and a second nozzle, ejects a first liquid flow from the first nozzle, and ejects a second liquid flow from the second nozzle;
A rotation mechanism for rotating the polishing pad relative to the wafer holder and the first nozzle and the second nozzle;
A chemical mechanical polishing apparatus comprising:
The first nozzle and the second nozzle are arranged so that the first liquid flow and the second liquid flow partially overlap when viewed along the rotation direction of the polishing pad.
Chemical mechanical polishing equipment.   The first cross section of the first liquid flow at the position reaching the polishing pad and the second cross section of the second liquid flow at the position reaching the polishing pad are respectively dimensions along the rotation direction of the polishing pad. 2. The chemical mechanical polishing apparatus according to claim 1, wherein the first nozzle and the second nozzle are configured so that a dimension along a direction away from a rotation axis of the polishing pad is larger than that of the polishing pad. The first nozzle and the second nozzle are arranged such that the first cross section is located closer to the rotation axis of the polishing pad than the second cross section; and
The first nozzle and the second nozzle are arranged so that the first cross section is located upstream of the second cross section in the rotation direction of the polishing pad.
The chemical mechanical polishing apparatus according to claim 2. The first nozzle or the second nozzle has the directional component toward the upstream side in the rotation direction of the polishing pad so that the first liquid flow or the second liquid flow reaches the polishing pad. Arranged at an angle to the rotation axis of the polishing pad,
The chemical mechanical polishing apparatus according to claim 1. The central axis of the first liquid flow or the second liquid flow has an inclination of 5 ° or more and 50 ° or less toward the upstream side in the rotation direction of the polishing pad with respect to the rotation axis of the polishing pad. The first nozzle or the second nozzle is disposed.
The chemical mechanical polishing apparatus according to claim 1. A conditioner for conditioning the polishing pad;
The first nozzle and the second nozzle are disposed upstream of the wafer holding unit in the rotation direction of the polishing pad, and the conditioner is disposed further upstream.
The chemical mechanical polishing apparatus according to claim 1.

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