JP5210444B1 - Polishing head and polishing processing apparatus - Google Patents

Abstract

An object of the present invention is to prevent uneven polishing, insufficient polishing or overpolishing of a surface to be processed of a substrate.
A polishing apparatus includes a polishing table in which a polishing pad having a polishing surface is bonded to a surface portion, and a polishing head for holding a substrate and pressing the surface to be processed against the polishing surface. And at least one is rotated horizontally. The polishing head 13 has a plurality of pressure chambers partitioned by partition walls 140, 132, and 134, and these pressure chambers respectively apply a pressing force corresponding to the amount of pressure fluid enclosed to the back side of the substrate W. From. Furthermore, the partition 140 itself also applies a pressing force with the pressure fluid. Thereby, the to-be-processed surface of the substrate W, including the back side of the portion where the partition wall 140 is provided, is almost uniformly pressed against the polishing surface. Further, by making the pressing surface in contact with the back side of the substrate W smaller in size than the surface to be processed of the substrate W, the stress applied to the surface to be processed is changed from the central portion to the beginning of the chamfer portion by the diffusion propagation of Hertz stress. Almost uniform.
[Selection] Figure 2

Description

  The present invention relates to a polishing head and a polishing apparatus for polishing and flattening a substrate such as a semiconductor wafer or a glass substrate.

In recent years, in the manufacturing process of a semiconductor device, with the increase in size of a substrate, a technology for planarizing the surface of the substrate has become increasingly important. Among the planarization techniques, the most important technique is chemical mechanical polishing (CMP). This chemical mechanical polishing is performed by supplying a polishing liquid containing abrasive grains such as silica (SiO ₂ ) onto a polishing surface such as a polishing pad using a polishing processing apparatus (also called a polishing apparatus). The polishing process is performed by sliding on the polishing surface.

In such a polishing apparatus, the relative pressing force between the surface of the substrate (hereinafter referred to as “processed surface”) and the polishing pad is not uniform over the entire surface to be processed. As a result, uneven polishing, insufficient polishing, or excessive polishing occurs. In addition, since the polishing pad has elasticity, the pressing force applied to the vicinity of the outer peripheral edge of the substrate becomes non-uniform, and only the vicinity of the outer peripheral edge may be overpolished.
The holding surface of the substrate is formed of an elastic film (also called a membrane) made of an elastic material such as rubber, and fluid pressure such as air pressure is applied to the back surface of the elastic film to make the pressing force applied to the substrate uniform over the entire surface. Attempts have also been made.

  From the viewpoint of making the pressing force applied to the substrate uniform, there is a substrate holding device disclosed in Patent Document 1. In this substrate holding device, the inside of the edge back that presses the substrate is divided into a first pressure chamber and a second pressure chamber, and each is controlled independently, thereby controlling the polishing rate at the outer peripheral edge of the substrate. That is, it is possible to control the polishing profile at the outer peripheral edge.

  Further, in the polishing apparatus disclosed in Patent Document 2, by providing a diaphragm made of a material having a rigidity higher than that of the elastic film so as to straddle two adjacent pressure chambers, all boundaries between two adjacent regions are provided. , The polishing pressure, and hence the polishing removal rate, gradually decreases from one chamber side (the chamber side where the pressure is high) toward the other chamber side (the chamber side where the pressure is low). In all cases, the gradient of the polishing pressure (polishing rate) is made gentle.

JP 2003-175455 A JP 2009-131920 A

In the substrate holding device disclosed in Patent Document 1, the interior of the edge back is divided into a first pressure chamber and a second pressure chamber, and each is controlled independently. However, there remains a problem that a pressing force for pressing the substrate vertically downward is not applied from the lower bottom surface of the partition wall separating the adjacent first pressure chamber and second pressure chamber.
In the polishing apparatus disclosed in Patent Document 2, the gradient of the polishing pressure can be made smooth by providing a diaphragm. However, the bottom surface of the partition wall (the boundary 20 in this document) sandwiched between two adjacent pressure chambers. Therefore, there is a problem that the substrate cannot be pressed vertically downward with a pressing force equivalent to that of the pressure chamber.

  The present invention prevents the occurrence of uneven polishing, insufficient polishing, and overpolishing depending on the pressing force applied to each part of the substrate, and a desired pressing force over the entire surface to be processed of the substrate. It is a main object to provide a polishing processing apparatus and a constituent device thereof capable of providing the above-described characteristics.

A polishing head of the present invention that solves the above problems is a polishing head provided in a polishing apparatus having a horizontally rotating polishing surface, and a substrate to be polished is a surface to be processed on the polishing surface. A holding mechanism that holds the sliding surface in contact with the holding mechanism; and a pressing mechanism that presses the substrate held by the holding mechanism from the back side of the surface to be processed toward the polishing surface.
In the pressing mechanism, one or a plurality of first partition walls that also serve as reinforcing ribs at the time of displacement are projected from a predetermined portion of the inner bottom surface , and the outer bottom surface serves as a pressing surface in contact with the surface to be processed of the substrate. By joining the cylindrical body and a part of the tip of the first partition wall , the pressure fluid is individually sealed in the internal space of the elastic cylindrical body together with the first partition wall , thereby the back surface of the substrate. A lid having a second partition that forms a plurality of pressure chambers that apply a pressing force in accordance with the amount of the pressure fluid to the side, and a part of the first partition and the second partition that separates these pressure chambers Or a fluid supply mechanism that is entirely formed into a shape that imparts a pressing force generated by the pressure fluid to the back side of the substrate, and supplies the pressure fluid to each of the plurality of pressure chambers. The pressing surface is smaller than the surface to be processed. A's, among the pressure fluid of the front end portion of the first partition wall, is configured to impart a pressing force to the back side of the substrate through the site to form a part of the inner wall of the pressure chamber.
According to this polishing head, a pressing force corresponding to the amount of the pressure fluid sealed in the plurality of pressure chambers is applied from each pressure chamber to the back side of the substrate. By adjusting the amount, the pressing force can be made uniform. Further, part or all of the first partition wall and the second partition wall are also formed in a shape that imparts a pressing force by themselves, so that the pressing force is applied to the entire surface to be processed regardless of the presence of the partition wall. It can be applied continuously.

The pressing mechanism includes, for example, one or a plurality of first partition walls that also serve as reinforcing ribs at the time of displacement at a predetermined portion of the inner bottom surface, and a pressing surface whose outer bottom surface is in contact with the surface to be processed of the substrate. And a second partition that forms the plurality of pressure chambers in the internal space of the elastic tubular body together with the first partition by joining to a part of the tip of the first partition. A lid, and a fluid supply mechanism for supplying the pressure fluid to each of the plurality of pressure chambers.
The pressing surface is smaller in size than the surface to be processed, and the pressure fluid is configured to apply a pressing force to the back side of the substrate through the remaining portion of the tip of the first partition.
This corrects the non-uniformity of the pressing force applied to the vicinity of the outer peripheral edge of the substrate and prevents “sag” of the surface to be processed, that is, over-polishing (ROA: Roll Off Amount). it can.

  In one embodiment, at least one of the plurality of pressure chambers is provided with an airbag that is made of a soft material and inflates by applying the pressure fluid to apply a pressing force to the pressing surface. Thereby, even if the airtightness of the pressure chamber is not sufficient, adjustment of the pressing force by the pressure fluid is facilitated, so that design and manufacture are facilitated. In addition, each component can be easily attached.

  In one embodiment, the second partition wall is detachably joined to a front end portion of the first partition wall, and when the pressure fluid is sealed in the airbag, a part of the airbag is the first partition wall. It is configured to enter the joining portion between the tip of the first partition and the second partition and release the joint, thereby applying a pressing force from the tip of the first partition to the back side of the substrate. Yes.

  In one embodiment, the holding mechanism is disposed on the outer peripheral side of the elastic cylindrical body, and includes a retainer ring having a gripping surface that contacts the outer end surface of the substrate and a positioning surface that contacts the polishing surface. And an elevating mechanism that elevates and lowers the retainer ring in a direction perpendicular to the pressing surface, and the elevating mechanism is configured so that the positioning surface of the retainer ring is flush with the surface to be processed of the substrate during polishing processing. It lowers until it becomes, and after the polishing process, it is raised above the pressing surface. The elevating mechanism is configured to elevate and lower the retainer ring according to the amount of pressure fluid supplied independently from the plurality of pressure chambers, for example.

A polishing apparatus according to the present invention includes a polishing table having a circular or substantially circular polishing surface, a polishing head that holds a substrate to be polished, and makes the circular target surface of the substrate slidably contact the polishing surface. And a drive mechanism for horizontally rotating at least one of the polishing head and the polishing table, wherein the polishing table is configured such that the radius of the polishing surface is larger than the diameter of the surface to be processed of the substrate. The polishing head includes a holding mechanism that holds the substrate so that a surface to be processed is in sliding contact with the polishing surface, and the substrate held by the holding mechanism from the back side of the surface to be processed. A pressing mechanism that presses in the direction of the inner surface, and the pressing mechanism has one or a plurality of first partition walls that also serve as reinforcing ribs at the time of displacement protruding from a predetermined portion of the inner bottom surface, and the outer bottom surface is An elastic cylindrical body that is a pressing surface in contact with the surface to be processed of the substrate, and a part of the tip of the first partition wall are joined to the internal space of the elastic cylindrical body together with the first partition wall. And a plurality of pressure chambers, each of which includes a second partition wall that forms a plurality of pressure chambers for applying a pressing force corresponding to the amount of the pressure fluid on the back surface side of the substrate. A fluid supply mechanism for supplying the pressure fluid to each of The pressing surface is smaller in size than the surface to be processed, and the pressure fluid is pressed against the back side of the substrate through a portion where the pressure fluid forms a part of the inner wall of the pressure chamber in the tip of the first partition wall. Configured to grant .

  In one embodiment, the pressing mechanism of the polishing apparatus includes an elastic cylindrical body whose outer bottom surface serves as a pressing surface in contact with the processing surface of the substrate, and the pressing surface is an outer peripheral end of the processing surface. Is formed in a small size by a predetermined size on the inner peripheral side.

  According to the polishing head of the present invention, in the polishing apparatus, a desired pressing force can be applied over the entire surface to be processed of the substrate without any discontinuous portions. Therefore, it is possible to achieve a special effect that uneven polishing, uneven polishing, and excessive polishing are prevented from occurring due to uneven pressing force.

The schematic block diagram of the grinding | polishing processing apparatus of 1st Embodiment. 1 is a schematic longitudinal sectional view of a polishing head according to a first embodiment. (A) The longitudinal cross-sectional view for demonstrating distribution of the pressing force given to a board | substrate at the time of using the conventional elastic film. (B) is a distribution graph of pressing force. (A) is a longitudinal cross-sectional view for demonstrating distribution of the pressing force given to a board | substrate at the time of using the elastic film of 1st Embodiment. (B) is a distribution graph of pressing force. (A) (b) The figure for demonstrating the structure of the press surface for preventing the roll-off generation | occurrence | production provided in the elastic film of 1st Embodiment. (A) (b) is a figure for demonstrating the experimental apparatus for specifying the optimal size of a press surface. (A) (b) is a longitudinal cross-sectional view for demonstrating the structure and function of a retainer ring. The whole procedure explanatory drawing of the grinding | polishing processing method performed in a grinding | polishing processing apparatus. The schematic longitudinal cross-sectional view of the polishing head of 2nd Embodiment. (A) is a longitudinal cross-sectional view for demonstrating distribution of the pressing force given to a board | substrate at the time of using the elastic film of 2nd Embodiment. (B) is a distribution graph of pressing force. (A) is another example of the elastic film of 2nd Embodiment, and is a longitudinal cross-sectional view for demonstrating distribution of the pressing force given to a board | substrate at the time of using this. (B) is a distribution graph of pressing force.

Embodiments of the present invention will be described below with reference to the drawings.
The polishing processing apparatus according to the present embodiment uses a substrate such as a semiconductor wafer or a glass substrate as a processing target substrate. In this specification, one surface of the substrate is a circular or substantially circular surface to be processed.
The polishing apparatus includes a polishing table to which a polishing pad to be a polishing member is bonded, a polishing table for rotating the polishing pad horizontally, and a polishing head for sliding the substrate surface to be processed to face the polishing pad. Have.
The substrate is pressed against the polishing pad by the polishing head. Then, the surface to be processed is polished by rotating at least one of the polishing table and the polishing head while supplying a polishing liquid (slurry) to the polishing pad.
Hereinafter, embodiments of this polishing apparatus will be described.

[First Embodiment]
FIG. 1 is a schematic configuration diagram of a polishing processing apparatus 1. A polishing processing apparatus 1 shown in FIG. 1 has a polishing pad 12 bonded to a surface portion of a polishing table 11, a polishing head 13 that holds a substrate W and presses the surface to be processed against the polishing pad 12, and polishing. A nozzle N for supplying the liquid toward the polishing pad 12, a motor (not shown) for horizontally rotating the polishing table 11 and the polishing head 13, and a polishing liquid supply mechanism (not shown) connected to the nozzle N And a control unit 20 including a computer for controlling each drive unit including a motor.

The polishing pad 12 has a disk shape, and the radius thereof is larger than the diameter of the surface to be processed of the substrate W. As a result, the surface to be processed of the substrate W does not have to pass near the center of the polishing pad 12 during the polishing process. This is because the movement speed is different between the vicinity of the center of the polishing pad 12 and the periphery thereof, and the polishing efficiency is improved when the surface to be processed of the substrate W is in sliding contact with the vicinity of the periphery having a high relative movement speed. It is because it is good in raising.
The polishing pad 12 itself has elasticity, and a commercially available material such as a non-woven fabric or a urethane foam can be used.

  The polishing head 13 holds the substrate W so that the surface to be processed is in sliding contact with the polishing pad 12, and a pressure for pressing the held substrate W from the back surface of the surface to be processed toward the polishing pad 12. Mechanism. These mechanisms will be described later.

The control unit 20 controls the positioning of the nozzle N, the supply start or stop control of the polishing liquid from the nozzle N, the supply amount control per unit time of the polishing liquid supplied from the nozzle N, the motor start start and start stop control, etc. Mainly. The rotational force of the motor controlled by the control unit 20 is transmitted to the polishing table 11 via a drive unit (not shown). As a result, the polishing table 11 rotates horizontally or stops rotating.
The rotational force of the motor is also transmitted to the polishing head 13 via a drive unit (not shown) (for example, a universal joint). As a result, the polishing head 13 rotates horizontally or stops rotating.

  The rotation direction of the polishing table 11 and the rotation direction of the polishing head 13 are the same. This is because if the direction is reversed, non-uniform polishing may occur. Although in the same direction, the polishing accuracy can be increased by adjusting the rotation speed.

  The rotational force of a single motor may be transmitted to the polishing table 11 and the polishing head 13 through gears having different gear ratios, or the rotational force may be transmitted through individual motors. good. Both can be designed arbitrarily. The control procedure by the control unit 20 will be described later.

  The polishing liquid is supplied from the nozzle N toward the polishing pad 11 for a predetermined time in a state where the rotation speed of the polishing table 12 reaches a predetermined value under the control of the control unit 20.

<Polishing head>
Next, the configuration of the polishing head 13 will be described in detail. FIG. 2 is a schematic longitudinal sectional view of the polishing head 13. The polishing head 13 roughly includes a holding mechanism and a pressing mechanism.
The holding mechanism is for preventing the substrate W biased by the rotational force of the polishing table 11 and the polishing head 13 from jumping out toward the outer peripheral direction, and the surface to be processed of the substrate W is attached to the polishing pad 12. In a state of being opposed (contacted) and in sliding contact, the central axis of the substrate W is held so that its rotation axis coincides.

Specifically, a retainer ring 137 having a gripping surface that comes into contact with the outer end portion of the substrate W and a positioning surface that comes into contact with the polishing surface, and raising and lowering that raises and lowers the retainer ring 137 in a direction perpendicular to the pressing surface. A fluid supply mechanism (not shown) that increases or decreases the amount of pressurized fluid (for example, compressed air) to the retainer ring holder 139 and the retainer ring airbag 138 by the control of the retainer ring airbag 138 and the control unit 20. It is comprised including.
The retainer ring airbag 138 increases the amount of pressure fluid during the polishing process and lowers the retainer ring 137 until its positioning surface is flush with the surface to be processed of the substrate W, and collects the pressure fluid after the polishing process. Then, it is raised above the pressing surface.

  The pressing mechanism includes an elastic cylindrical body and a lid body as a casing, and a plurality of pressure chambers are formed in the casing. A top ring 131 connected to a drive unit (not shown) corresponds to the lid. The cylindrical body corresponds to a partition support ring 132 connected to the top ring 131 and a ring-shaped upper portion supported via a seal ring 141 (described later) locked to the partition support ring 132 with a bolt 133. A partition wall 134, an outer diameter ring 135 connected to the partition wall support ring 132, and an elastic membrane (“membrane”) provided in a cylindrical shape (pan-shaped) so as to cover a part of the outer peripheral side surface of the outer diameter ring 135 Is also called.) 136.

The elastic film 136 is formed of a rubber material having excellent strength and durability, such as ethylene propylene rubber (EPDM), polyurethane rubber, and silicon rubber. The elastic membrane 136 is formed with an inner diameter size that can be fitted to the outer peripheral surface of the outer diameter ring 135.
The outer bottom surface (“pressing surface”) of the elastic film 136 that contacts the back side of the surface to be processed of the substrate W is formed in a size smaller than the outer peripheral edge of the substrate W. Details will be described later.

A ring-shaped lower partition 140 that also serves as a reinforcing rib for maintaining the shape of the elastic film 136 even when rotating is projected from a predetermined portion of the inner bottom surface of the elastic film 136. A part of the tip of the lower partition 140, for example, the outer half of the lower partition 140, is formed so as to be joined to a predetermined portion of the upper partition 134. As a result, a space ("first pressure chamber") surrounded by the top ring 131, the partition support ring 132, the upper partition 134, the lower partition 140, and the elastic film 136 on the inner peripheral side of the lower partition 140, and the partition support ring A space (“second pressure chamber”) surrounded by 132 and the upper partition 134, the outer diameter ring 135, the lower partition 140, and the elastic film 136 on the outer peripheral side of the lower partition 140 is formed.
By supplying a pressure fluid (for example, compressed air) to these two pressure chambers, it is possible to individually adjust the pressing force applied to the vicinity of the center portion of the substrate W and the pressing force applied to the vicinity of the outer peripheral edge. become.

 The surface where the partition support ring 132 and the upper partition 134 are connected in the first pressure chamber is sealed with a seal ring 141, and the upper partition 134 and the lower partition 140 are also sealed and joined. The confidentiality of each of the first pressure chamber and the second pressure chamber is increased.

The polishing head 13 is provided with fluid paths 142a, 142b, 142c connected to a fluid supply mechanism (not shown).
The fluid path 142a is for supplying pressure fluid toward the first pressure chamber or for recovering the supplied pressure fluid from the first pressure chamber.
The fluid path 142b supplies the pressure fluid toward the second pressure chamber, or collects the supplied pressure fluid from the second pressure chamber.
The fluid path 142c supplies pressure fluid toward the retainer ring airbag 138, or collects the supplied pressure fluid from the retainer ring airbag 138.

  Note that each of the fluid paths 142a to 142c is connected to the above-described fluid supply mechanism, and under the control of the control unit 20, the pressure fluid is independently supplied, or the supplied pressure fluid is recovered.

  The retainer ring 137 described above is positioned on the outer peripheral side of the elastic film 136 so as to surround the outer periphery of the substrate W, and holds the outer peripheral end of the substrate W in surface contact. In addition to holding the substrate W, the retainer ring 137 presses the polishing pad 12 by supplying pressurized fluid to the retainer ring airbag 138 during the polishing process, and releases the contact with the surface to be processed of the substrate W. To work.

Next, the pressing force applied to the substrate W will be described.
When polishing the substrate W, the control unit 20 performs control so that a predetermined amount of pressure fluid is supplied to each of the first pressure chamber and the second pressure chamber.
Here, FIG. 3A schematically shows the state of the pressing force applied from each pressure chamber partitioned by a general partition wall that does not depend on the polishing head 13 of the present embodiment.

Referring to FIG. 3, the pressure fluid P1 and P2 (when P1> P2) is supplied from the pressing surface to the substrate by supplying the pressure fluid to each of the first pressure chamber and the second pressure chamber separated by the partition wall. It is given to the back surface of W (the back surface side of the surface facing the polishing pad 12). P1 is the pressing force of the first pressure chamber, and P2 is the pressing force of the second pressure chamber.
FIG. 3B shows the distribution of the pressing force in this case. In the graph of FIG. 3B, the vertical axis represents the pressing force (P), and the horizontal axis represents the surface to be processed. It is assumed that the outer edge is closer to the front right side of the figure with the origin as the center of the substrate W. As shown in FIG.3 (b), from the pressing surface of the back side of the site | part in which the partition was provided, it becomes low concavely compared with the pressing force P1, P2 adjacent to right and left, and the to-be-processed surface corresponding to this position Then, insufficient polishing occurs and polishing unevenness occurs.

  When the pressing force P1 of the first pressure chamber and the pressing force P2 of the second pressure chamber propagate in the pressing surface, a pressing force portion considerably lower than these pressing forces P1 and P2 is generated, and polishing unevenness occurs. .

FIG. 4A schematically shows the state of the pressing force applied to the first and second pressure chambers in the polishing head 13 of the present embodiment. The pressure fluid is supplied to the first pressure chamber and the second pressure chamber, respectively, so that the pressing forces P1 and P2 (when P1> P2) are slidably contacted with the polishing pad 12 from the pressing surface. It is the same as in the case of FIG.
However, when the polishing head 13 of this embodiment is used, the tip of the lower partition 140 is divided into a portion that forms part of the inner wall of the first pressure chamber and a portion that contacts the upper partition 134. The pressure P1 of the first pressure chamber acts on the former part, and the pressure P1 of the first pressure chamber acts on the latter part via the upper partition wall 134. Therefore, the pressure receiving surface pressure of the pressing force P1a is transmitted to the upper bottom surface of the lower partition 140. That is, the pressing force P1 acts vertically downward through the tip of the lower partition 140. Therefore, the pressing force P <b> 1 is also applied to the back surface side of the substrate W that is in sliding contact with the polishing pad 12 from the pressing surface on the back surface side of the portion where the lower partition wall 140 protrudes. Further, in the second pressure chamber, a pressing force P <b> 2 acts on the lower partition 140 from the upper part of the upper partition 134.

  This is shown in the graph of FIG. 4B, which is shown by a graph having a vertical axis and a horizontal axis similar to those in FIG. As shown in FIG. 4B, when the polishing head 13 of this embodiment is used, the pressing force P1 is slidably contacted with the polishing pad 12 from the pressing surface on the back side of the portion where the lower partition wall 140 protrudes. Since it is applied to the back side of the substrate W thus formed, it can be seen that the influence of the presence of the lower partition 140 is remarkably mitigated as compared with the structure of FIG.

  Here, the case where two pressure chambers are formed has been described as an example. However, for example, the protruding portion of the lower partition 140 is changed, or the number of pressure chambers is increased by providing more lower partitions 140. It is also possible to optimize the way of applying the pressing force in accordance with the polishing characteristics of the substrate W.

<Preventing roll-off>
Next, roll-off will be described. In general, the substrate (W) to be polished is chamfered (processed to remove corners) in the vicinity of the outer periphery. Therefore, the substrate surface in the vicinity of the outer periphery is not completely flat. Roll-off means sagging of the substrate surface in the vicinity of the outer periphery of the substrate. The smaller the roll-off is, the closer the substrate is to be completely flat. On the contrary, the larger the roll-off is, the smaller the flat area of the substrate is. In this embodiment, the structure for preventing this roll-off is also devised.

Hereinafter, a structure for preventing roll-off will be described with reference to FIG.
FIG. 5A shows the distribution of stress applied to the surface to be processed in sliding contact with the polishing pad 12 when a pressing force is applied through the elastic film 136 having a size larger than the surface to be processed and the back surface of the substrate W. Is shown. A buffer portion called a chamfer is usually formed at the outer peripheral end of the substrate W. The chamfer portion has an effect of preventing the entire substrate W from being damaged by being lost and absorbing the impact when receiving an impact from the outside.
However, on the other hand, the chamfer portion has a corner at the corner and a non-contact portion with the polishing pad from the corner toward the outer periphery, so that the pressing force P2 is applied almost uniformly toward the substrate W. Nevertheless, the closer to the chamfer part, the higher the stress applied to the surface to be processed by Hertzian stress theory, and the maximum is at the beginning of the chamfer part. This change in stress causes overpolishing and roll-off occurs.

  Therefore, in the present embodiment, as shown in FIG. 5B, the pressing surface of the elastic film 136 is formed in such a size that the outer peripheral end is located on the inner peripheral side of the chamfer portion of the substrate W. The elastic film 136 has a cylindrical shape with a thickness of about 2 [mm], for example, but the size of the pressing surface is larger than the diameter of the surface to be processed of the substrate W from the outer peripheral end of the substrate W. Then, it is formed in a size smaller by a predetermined size on the inner peripheral side. This predetermined size is referred to as overhang (OH).

  FIG. 5B shows the distribution of the pressing force applied to the surface to be processed in sliding contact with the polishing pad 12 when the pressing force P2 is applied from the pressing surface toward the substrate W. The pressing force P <b> 2 applied toward the substrate W is not applied from the outer peripheral edge of the substrate W to the inner peripheral side by OH through the pressing surface of the elastic film 136. However, the outer peripheral end of the surface to be processed is in sliding contact with the polishing pad 12 on the outer peripheral side of the outer peripheral end vertically below the pressing surface. Therefore, the pressing force P2 is diffused and propagated in the substrate W, and the stress applied to the surface to be processed is substantially uniform from the center portion to the start end of the chamfer portion (diffuse propagation of Hertz stress). Thereby, roll-off can be prevented.

The OH is about 1 [mm] in this embodiment, but the optimum OH is determined according to the size of the substrate W and the elastic modulus of the polishing pad. This optimal OH can be obtained by, for example, a ROA (Roll Off Amount) experimental apparatus shown in FIGS. 6 (a) and 6 (b). 6A is a schematic longitudinal sectional view of the ROA experimental apparatus, and FIG. 6B is a schematic top view of the ROA experimental apparatus.
When determining the optimum OH using the ROA experimental apparatus, first, a cylindrical weight having an elastic body is placed on the substrate W slidably in contact with the polishing pad 12. At that time, each center axis is shifted and placed as shown in FIG. 6B and polished. For example, assuming that the center of the substrate W is O, based on OH on each line such as OA, OB, OC, and OD, the “Optical Flat interference fringe” and “roughness gauge straightness” after the polishing are measured. . From the measurement results, an OH whose straightness of the surface to be processed is close to a straight line is selected as the optimum OH of the substrate W.

When polishing the substrate W, the pressurized fluid is supplied to the retainer ring airbag 138 so that the retainer ring 137 presses the polishing pad 12. Since the polishing pad 12 has elasticity as described above, when the pressing force is applied toward the substrate W, the polishing pad 12 may cover the periphery of the side end portion of the substrate W, and this also causes the surface to be processed. It becomes a factor of overpolishing around the side edge of the steel. That is, roll-off occurs.
Therefore, in this embodiment, as shown in FIG. 7A, a pressing force P3 is applied to the retainer ring 137 so that the surface to be processed of the substrate W and the lower bottom surface of the retainer ring 137 are in a half-contact state. The polishing pad 12 was pressed. Thereby, overpolishing near the outer peripheral edge of the substrate W can be prevented.

  Further, the pressure fluid supplied to the retainer ring airbag 138 can be recovered, and the retainer ring 137 can be raised to a predetermined position as shown in FIG. 7B. For example, after the polishing process of the substrate W is completed, jet water is sprayed and supplied in the horizontal direction toward the gap between the retainer ring 137 and the polishing pad 12 with the retainer ring 137 raised. Thereby, the substrate W in a state of being in close contact with the pressing surface of the elastic film 136 can be easily peeled off by the pressing force.

<Control procedure for polishing>
Next, a polishing process procedure performed by the polishing apparatus 1 according to this embodiment will be described. FIG. 8 is an explanatory diagram of main control procedures by the control unit 20 when executing the polishing method.
The control unit 20 starts control upon receiving an input of a start instruction by the operator of the polishing processing apparatus 1 (step S100). After the predetermined initial processing, the substrate W is carried in by a substrate transfer means (not shown), and the substrate W is held by the holding mechanism of the polishing head 13 (step S101).
The control unit 20 instructs the fluid supply mechanism so that a predetermined amount of pressurized fluid is supplied from the fluid paths 142a, 142b, and 142c, and applies a pressing force toward the substrate W and the polishing pad 12 (step S102).

  The control unit 20 also checks whether an appropriate pressing force is applied to the substrate W or an appropriate pressing force is applied to the retainer ring 137 through a sensor unit (not shown). When it is confirmed that the pressing force is appropriate (step S103: Yes), an instruction is given to a motor (not shown) to start the rotation of the polishing table 11 and the polishing head 13 (step S104). As a result, the polishing table 12 and the polishing head 13 start to rotate horizontally.

After instructing the rotation start of the polishing table 11 and the polishing head 13, the control unit 20 instructs the positioning of the nozzle N and instructs the polishing liquid supply mechanism to start supplying the polishing liquid (step). S105). As a result, the polishing liquid is supplied from the nozzle N toward the polishing surface of the polishing pad 12.
When a timer (not shown) detects that a predetermined polishing time has passed after the polishing liquid supply start instruction (step S106: Yes), the control unit 20 instructs the polishing liquid supply mechanism to stop supplying the polishing liquid. (Step S107).

  Thereafter, the control unit 20 issues a stop instruction to the motor so as to stop the rotation of the polishing table 11 and the polishing head 13 (step S108), and issues an instruction to the pressure fluid supply mechanism to collect the supplied pressure fluid. (Step S109). And the board | substrate W is carried out by the board | substrate conveyance means which is not shown in figure. This completes the polishing process.

  As described above, in the polishing processing apparatus 1 according to the present embodiment, the pressing force P1 of the first pressure chamber is caused by the combination of the upper partition wall 134 and the lower partition wall 140 so that the elastic film 136 on which the lower partition wall 140 protrudes. It also acts on the back side of the site. Therefore, the substrate W can be pressed vertically downward with the entire pressing surface. Thereby, it is possible to prevent the occurrence of insufficient polishing or excessive polishing depending on the portion of the surface to be processed. Furthermore, by changing the way of joining the upper partition wall 134 and the lower partition wall 140, a desired pressing force can be applied over the entire surface to be processed.

  Further, the pressing surface of the elastic film 136 is formed so as to press the substrate W in a state in which the peripheral edge is in contact with the inner peripheral side from the outer peripheral end of the substrate W. Thereby, it is possible to prevent “sag” of the surface to be processed in the vicinity of the outer peripheral edge of the substrate W, that is, occurrence of overpolishing.

Further, the retainer ring 137 can be moved by supplying or collecting the pressure fluid to the retainer ring airbag 138.
As a result, the polishing pad 12 can be pressed so that the surface to be processed of the substrate W and the lower bottom surface of the retainer ring 137 are in a semi-contact state, and overpolishing near the outer peripheral edge of the substrate W can be prevented. it can.
Further, a gap is formed between the lower bottom surface of the retainer ring 137 and the surface of the polishing pad 12, and jet water is sprayed and supplied from the horizontal direction toward the gap, thereby being brought into close contact with the pressing surface of the elastic film 136. The substrate W in the state of being able to be peeled can be easily peeled off.

[Second Embodiment]
Next, an embodiment will be described in which an airbag is provided in each of the space of the first pressure chamber and the space of the second pressure chamber, and a pressure fluid is supplied to each airbag to apply a pressing force to the substrate W. To do.
FIG. 9 is a schematic longitudinal sectional view showing a configuration example of the polishing head 15 of the second embodiment.
About the part which overlaps with what was demonstrated in 1st Embodiment, the same code | symbol is used and duplication description is abbreviate | omitted. The main structural difference from the polishing head 13 of the first embodiment is the difference in the shape and arrangement of the upper partition wall and the lower partition wall in addition to the provision of the airbag in each pressure chamber space. .

The polishing head 15 according to the second embodiment includes a partition wall support ring 151 connected to the top ring 131.
The polishing head 15 also includes a partition upper cover 153 that is connected to the partition support ring 151 and has a ring-shaped upper partition 152 that protrudes vertically downward. In addition, a ring-shaped lower partition 154 that protrudes vertically upward is formed opposite to the upper partition 152, and an elastic film 155 that covers a part of the outer peripheral surface of the partition support ring 151 is provided.
The polishing head 15 further includes a first pressure chamber airbag 156 formed so as to cover an inner wall of a space (first pressure chamber) surrounded by the partition upper lid 153 and the elastic film 155, a partition upper lid 153, a partition And a second pressure chamber airbag 157 formed to cover the inner wall of the space (second pressure chamber) surrounded by the support ring 151 and the elastic membrane 155.

  The surfaces of the upper partition 152 formed on the partition upper cover 153 and the lower partition 154 formed on the elastic film 155 face each other in a semicircular cross section as shown in FIG. Contact is possible.

FIG. 10A schematically shows the pressing force applied from each pressure chamber in the configuration of this embodiment.
By supplying pressurized fluid to the first pressure chamber airbag 156 and the second pressure chamber airbag 157, respectively, the pressing forces P1 and P2 are moved from the pressing surface to the back side of the substrate W that is in sliding contact with the polishing pad 12. Is granted. Further, the pressure fluid supplied to the first pressure chamber airbag 156 and the second pressure chamber airbag 157 enters from the outer peripheral side of the surface where the upper partition wall 152 and the lower partition wall 154 face each other. 152 and the lower partition 154 are separated from each other, and the pressing force Pb is applied to the back side of the substrate W that is in sliding contact with the polishing pad 12 from the pressing surface on the back side of the portion where the lower partition 154 is formed. Is done.

Since the pressing force Pb is a combination of the pressing force P1 and the pressing force P2 (when P1> P2), in this case, the lower partition 154 is sandwiched from the first pressure chamber side to the second pressure chamber side. The pressing force decreases toward the end. This is shown in the graph shown in FIG. 10B, which is shown in a graph having a vertical axis and a horizontal axis similar to those in FIG.
As shown in FIG. 10B, a pressing force is also applied from the pressing surface on the back side of the portion where the partition wall is formed to the back side of the substrate W that is in sliding contact with the polishing pad 12.

  As described above, in the polishing processing apparatus provided with the polishing head 15, the pressure fluid supplied to the first pressure chamber airbag 156 and the second pressure chamber airbag 157 respectively separates the upper partition wall 152 and the lower partition wall 154. As shown in FIG. As a result, a pressing force is also applied from the pressing surface on the back surface side of the portion where the lower partition wall 154 is formed to the back surface side of the substrate W that is in sliding contact with the polishing pad 12, so that polishing is insufficient depending on the portion of the processing surface And over-polishing can be prevented.

Furthermore, by changing the shape and structure of the surfaces where the upper partition wall 152 and the lower partition wall 154 face each other, the pressing surface of the portion where the lower partition wall 154 is formed moves to the back side of the substrate W that is in sliding contact with the polishing pad 12. The applied pressing force can also be adjusted.
In addition, since the pressure fluid is supplied to each airbag, the necessity for forming each pressure chamber with high airtightness is reduced, and the cost advantage is increased, and the mounting of each component is facilitated.

<Modification>
Although the present embodiment is as described above, the present invention is not limited to the above-described embodiment, and can be implemented in various forms.
For example, as another example in the case where an airbag is provided in each of the space of the first pressure chamber and the space of the second pressure chamber, and a pressure fluid is supplied to the airbag to apply a pressing force toward the substrate W, As shown in FIG. 11 (a), the outer peripheral side surface of the upper partition wall and the inner peripheral side surface of the lower partition wall can be slidably brought into contact with each other.

  FIG. 11A schematically shows the state of the pressing force applied from each pressure chamber in the configuration of this modification. By supplying pressurized fluid to the airbag in the first pressure chamber and the airbag in the second pressure chamber, respectively, the pressing forces P1 and P2 are applied to the back side of the substrate W slidably contacted with the polishing pad 12 from the pressing surface. Is done. Furthermore, since the pressing force P2 also acts on the upper bottom surface portion of the lower partition wall by the pressure fluid supplied to the airbag of the second pressure chamber, the pressing force P2 also from the pressing surface on the back side of the portion where the lower partition wall is formed. Is applied to the back side of the substrate W in sliding contact with the polishing pad 12.

This is shown in the graph shown in FIG. 11B, which is shown in a graph having the same vertical and horizontal axes as in FIG. As shown in FIG. 11B, the pressing force P <b> 2 is also applied to the back side of the substrate W that is in sliding contact with the polishing pad 12 from the pressing surface on the back side of the part where the partition is formed.
The inner peripheral side surface of the upper partition wall and the outer peripheral side surface of the lower partition wall are slidably brought into contact with each other, so that the pressing force P1 is slidably contacted with the polishing pad 12 from the pressing surface on the back side of the part where the partition wall is formed. It can also be applied to the back side of the substrate W.

  DESCRIPTION OF SYMBOLS 1 ... Polishing processing apparatus, 11 ... Polishing table, 12 ... Polishing pad, 13, 15 ... Polishing head, 131 ... Top ring, 132, 151 ... Partition support ring, 133. .., bolts 134, 152 ... upper partition, 135 ... outer diameter ring, 136, 155 ... elastic membrane, 137 ... retainer ring, 138 ... retainer ring airbag, 139 Retainer ring holder, 140, 154 ... lower partition, 141 ... seal ring, 142a, 142b, 142c ... fluid path, 153 ... partition upper cover, 156 ... first pressure chamber airbag, 157 ... second pressure chamber airbag, W ... substrate, N ... nozzle.

Claims (7)

A polishing head provided in a polishing apparatus having a horizontally rotating polishing surface,
A holding mechanism for holding the substrate to be polished so that the surface to be processed is in sliding contact with the polishing surface;
A pressing mechanism that presses the substrate held by the holding mechanism in the direction of the polishing surface from the back side of the surface to be processed;
In the pressing mechanism, one or a plurality of first partition walls that also serve as reinforcing ribs at the time of displacement are projected from a predetermined portion of the inner bottom surface , and the outer bottom surface serves as a pressing surface in contact with the surface to be processed of the substrate. A tubular body;
When the pressure fluid is individually sealed in the internal space of the elastic cylindrical body together with the first partition wall by joining with a part of the tip of the first partition wall , the pressure fluid is placed on the back side of the substrate. A lid provided with a second partition wall that forms a plurality of pressure chambers for applying a pressing force according to the amount of
A part or all of the first partition wall and the second partition wall partitioning these pressure chambers are molded into a shape that itself gives a pressing force generated by the pressure fluid to the back side of the substrate,
A fluid supply mechanism for supplying the pressure fluid to each of the plurality of pressure chambers,
The pressing surface is smaller than the surface to be processed,
The inner pressure fluid of the front end portion of the first partition wall, is configured to impart a pressing force to the back side of the substrate through the site to form a part of the inner wall of the pressure chamber,
Polishing head. At least one of the plurality of pressure chambers is configured with a soft material, and an airbag that is inflated by sealing the pressure fluid and applies a pressing force to the pressing surface is mounted.
The polishing head according to claim 1 . The second partition is detachably joined to the tip of the first partition,
When the pressure fluid is sealed in the airbag, a part of the airbag enters the joint portion between the tip of the first partition and the second partition, thereby releasing the joint. It is comprised so that a pressing force may be given from the front-end | tip part of 1 partition to the back side of the said board | substrate,
The polishing head according to claim 2 . The holding mechanism is disposed on the outer peripheral side of the elastic cylindrical body, and has a retainer ring having a gripping surface that contacts the outer end surface of the substrate and a positioning surface that contacts the polishing surface;
An elevating mechanism that elevates and lowers the retainer ring in a direction perpendicular to the pressing surface;
The elevating mechanism lowers the retainer ring during polishing processing until its positioning surface is flush with the surface to be processed of the substrate, and raises it above the pressing surface after polishing processing.
The polishing head according to claim 3 . The elevating mechanism elevates and lowers the retainer ring in accordance with an amount of pressure fluid supplied independently from the plurality of pressure chambers;
The polishing head according to claim 4 . A polishing table having a circular or substantially circular polishing surface, a polishing head that holds a substrate to be polished, and makes the circular target surface of the substrate slidably contact the polishing surface, the polishing head, and the polishing table A drive mechanism for horizontally rotating at least one of
The polishing table is
The radius of the polishing surface is configured to be larger than the diameter of the surface to be processed of the substrate,
The polishing head is
A holding mechanism for holding the substrate such that a surface to be processed is in sliding contact with the polishing surface;
A pressing mechanism that presses the substrate held by the holding mechanism in the direction of the polishing surface from the back side of the surface to be processed;
In the pressing mechanism, one or a plurality of first partition walls that also serve as reinforcing ribs at the time of displacement are projected from a predetermined portion of the inner bottom surface, and the outer bottom surface serves as a pressing surface in contact with the surface to be processed of the substrate. A tubular body;
When the pressure fluid is individually sealed in the internal space of the elastic cylindrical body together with the first partition wall by joining with a part of the tip of the first partition wall , the pressure fluid is placed on the back side of the substrate. A lid provided with a second partition wall that forms a plurality of pressure chambers for applying a pressing force according to the amount of
A fluid supply mechanism for supplying the pressure fluid to each of the plurality of pressure chambers,
The pressing surface is smaller than the surface to be processed,
The pressure fluid is configured to apply a pressing force to the back side of the substrate through a portion forming a part of the inner wall of the pressure chamber in the front end portion of the first partition .
Polishing processing equipment. The pressing mechanism includes an elastic cylindrical body whose outer bottom surface serves as a pressing surface in contact with the surface to be processed of the substrate, and the pressing surface has a size that is smaller by a predetermined size from the outer peripheral end of the processing surface to the inner peripheral side. Formed,
The polishing apparatus according to claim 6 .

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