JP7780906B2 - CMP equipment - Google Patents

Description

The present invention relates to a CMP apparatus for CMP polishing of a workpiece.

In the semiconductor manufacturing field, CMP apparatuses are known for planarizing semiconductor wafers such as silicon wafers (hereinafter referred to as "workpieces").

The wafer polishing apparatus described in Patent Document 1 is a polishing apparatus that applies chemical mechanical polishing, or CMP (Chemical Mechanical Polishing) technology. In this wafer polishing apparatus, a wafer W is housed in an annular exchange unit 34, and the polishing head 1 polishes the wafer W by pressing it against the polishing cloth 2 using air pressure from an air chamber 61 formed in the gap between the carrier 20 and a rubber sheet 60 whose peripheral edge is held by a retainer ring 30. Note that the reference numerals are those of Patent Document 1.

Patent No. 3683149

However, in the wafer polishing apparatus described above, the wafer W collides with the inner surface of the replacement part 34 due to dynamic friction with the polishing cloth 2 during polishing, so the wafer W needs to be gently received. Furthermore, the replacement part 34 itself is also polished as the wafer W is polished, and repeated polishing causes the replacement part 34 to wear and thin, adversely affecting the polished shape of the wafer W, so it needs to be replaced periodically.

For example, if the replacement part 34 is made of a soft material, it will cushion the collision with the wafer W during polishing and reduce chipping of the wafer W, but the replacement part 34 will be more susceptible to wear, which will increase the frequency of replacement of the replacement part 34 and shorten the operating time of the equipment.

On the other hand, if the replacement part 34 is made of a highly wear-resistant material, the replacement part 34 will need to be replaced less frequently, but the wafer W will be more likely to chip due to collisions with the replacement part 34 during polishing.

This raises a technical issue that must be resolved in order to extend the operating time of the CMP equipment while suppressing chipping of the workpiece during CMP polishing, and the present invention aims to solve this issue.

To achieve the above objective, the CMP apparatus of the present invention is a CMP apparatus for polishing a workpiece, and includes a frame body formed with a storage pocket for storing the workpiece and pressed against a polishing pad together with the workpiece. The frame body includes a buffer section surrounding the storage pocket, and a reinforcing section that is integral with the buffer section, has higher wear resistance than the buffer section, and occupies at least a portion of the pressed surface of the frame body that is pressed against the polishing pad.

With this configuration, the reinforcing section, which has higher wear resistance than the buffer section, occupies at least a portion of the pressed surface of the frame, thereby suppressing wear on the frame and reducing the frequency of frame replacement, thereby extending the operating time of the CMP apparatus. Furthermore, because the buffer section receives the workpieces that move within the storage pocket during polishing, chipping of the workpieces during polishing can be suppressed.

The present invention can extend the operating time of a CMP device and reduce chipping of the workpiece during polishing.

1 is a perspective view schematically showing a CMP apparatus according to an embodiment of the present invention; FIG. 2 is a vertical cross-sectional view schematically showing a main part of the polishing head. FIG. FIG. 3 is an enlarged view of part I in FIG. 2 . FIG. 10 is a schematic diagram showing a state in which a workpiece is in contact with a frame during polishing. 10A and 10B are cross-sectional views showing the main parts of a frame in a CMP apparatus according to a modified example of the present invention, and schematic views showing a state in which a workpiece is in contact with the frame during polishing.

Embodiments of the present invention will be described with reference to the drawings. Note that, hereinafter, when referring to the number, numerical value, amount, range, etc. of components, unless otherwise expressly stated or when it is clearly limited to a specific number in principle, the number is not limited to that specific number and may be greater than or less than the specific number.

In addition, when referring to the shape or positional relationship of components, etc., this includes things that are substantially similar or approximate to that shape, etc., unless otherwise specified or when it is clearly considered otherwise in principle.

In addition, drawings may exaggerate characteristic parts to make their features easier to understand, and the dimensional proportions of the components may not be the same as in reality. In addition, in cross-sectional views, hatching of some components may be omitted to make the cross-sectional structure of the components easier to understand.

Figure 1 is a perspective view showing a schematic diagram of a CMP apparatus 1 according to one embodiment of the present invention. The CMP apparatus 1 polishes one surface of a workpiece W to a flat surface. The CMP apparatus 1 includes a platen 2 and a polishing head 10.

The platen 2 is formed in a disk shape and is connected to a rotating shaft 3 located below the platen 2. When the rotating shaft 3 is rotated by the drive of a motor 4, the platen 2 rotates in the direction of arrow D1 in Figure 1. A polishing pad 5 is affixed to the upper surface of the platen 2, and CMP slurry, a mixture of abrasives and chemicals, is supplied onto the polishing pad 5 from a nozzle (not shown).

The polishing head 10 is formed in a disk shape with a smaller diameter than the platen 2 and is connected to a rotating shaft 10a located above the polishing head 10. The rotating shaft 10a is rotated by a motor (not shown), causing the polishing head 10 to rotate in the direction of arrow D2 in FIG. 1. The polishing head 10 can be raised and lowered in the vertical direction V by an elevator (not shown). When polishing a workpiece W, the polishing head 10 descends and presses the workpiece W against the polishing pad 5. The workpiece W to be polished by the polishing head 10 is transferred by a work transport mechanism (not shown).

The operation of the CMP apparatus 1 is controlled by a controller (not shown). The controller controls each of the components that make up the CMP apparatus 1. The controller is, for example, a computer, and is composed of a CPU, memory, etc. The functions of the controller may be realized by control using software, or may be realized by hardware.

Next, the configuration of the polishing head 10 will be described with reference to Figures 2, 3, and 4. As shown in Figure 2, the polishing head 10 includes a head body 20, a carrier 30, a retaining ring 40, a membrane film 50, and a backing film 60.

The head body 20 is connected to the rotary shaft 10a and rotates together with the rotary shaft 10a. The head body 20 is connected to the carrier 30 located below the head body 20 via the rotating part 21, and the head body 20 and carrier 30 rotate in unison.

A carrier pressing means 31 is provided between the head main body 20 and the carrier 30. The carrier pressing means 31 is an air bag or the like that is inflated by air supplied from an air supply source (not shown). The pressure of the air supplied from the air supply source is adjusted by a regulator (not shown). The carrier pressing means 31 presses the workpiece W against the polishing pad 5 via the carrier 30 in accordance with the pressure of the supplied air.

Air lines 32 are provided on the carrier 30, spaced at equal intervals around its periphery. The lower ends of the air lines 32 open into air chamber A, formed between the underside 30a of the carrier 30 and the membrane film 50. The air lines 32 are connected to an air supply source (not shown), which serves as an air supply means, and air is introduced into air chamber A via the air lines 32. The pressure of the air supplied to the air lines 32 is adjusted by a regulator (not shown). The air supplied from the air lines 32 to air chamber A forms an air pressure layer in air chamber A that pushes back the pressure transmitted to the carrier 30 by the carrier pressing means 31, and by releasing excess pressure to the atmosphere, the workpiece W can be pressed with a uniform pressure distribution.

The lower surface 30a of the carrier 30 is provided with multiple elastic pressing members (not shown) arranged coaxially. Each pressing member is formed in an annular shape with a different diameter. The elastic pressing members are bolted to the lower surface 30a of the carrier 30 via a bracket (not shown). The elastic pressing members are arranged coaxially with the rotation axis 10a of the polishing head 10 and define air chamber A.

The retainer ring 40 is arranged to surround the periphery of the carrier 30. The retainer ring 40 has a frame body 41 with a membrane film 50 and a backing film 60 provided on its upper surface.

The frame 41 is formed in an annular shape and has a storage pocket 41a in its center for storing the workpiece W. The frame 41 is attached to a retainer pressing member 43 via a snap ring 42. A retainer pressing means 44 is provided between the head body 20 and the retainer pressing member 43. Reference numeral 45 denotes a cover that covers the top of the snap ring 42.

The retainer pressing means 44 is an air bag or the like that is inflated by air supplied from an air supply source (not shown). The pressure of the air supplied from the air supply source is adjusted by a regulator (not shown). The retainer pressing means 44 presses the retainer ring 40 against the polishing pad 5 via the retainer pressing means 44 in accordance with the pressure of the supplied air.

The membrane film 50 is made of a resin such as tetrafluoroethylene perfluoroalkoxyvinyl ether copolymer (PFA) or polyethylene terephthalate (PET). The membrane film 50 is bonded to the upper surface of the backing film 60, and when compressed air is introduced into the air chamber A, the air pressure causes the membrane film 50 to elastically deform toward the inside of the storage pocket 41a.

The backing film 60 is, for example, a suede film. The backing film 60 is attached to the frame 41 so as to cover the storage pocket 41a. When compressed air is introduced into the air chamber A, the backing film 60 elastically deforms in accordance with the elastic deformation of the membrane film 50, pressurizing the workpiece W.

As shown in Figure 4, the frame body 41 has a buffer portion 46 and a reinforcing portion 47.

The buffer section 46 is made of a resin such as glass epoxy, nylon (polyamide), polyether ether ketone (PEEK), or polyphenylene sulfide (PPS).

The reinforcing section 47 is made of a material that exhibits higher abrasion resistance than the buffer section 46, such as carbon fiber reinforced plastic (CFRP). CFRP is approximately 20 times more abrasion resistant than glass epoxy. CFRP also exhibits higher rigidity than glass epoxy, making it suitable for maintaining the shape of the buffer section 46 during CMP polishing.

The buffer portion 46 is formed in a generally annular shape in plan view, surrounding the storage pocket 41a formed in the center. The buffer portion 46 is exposed to the storage pocket 41a. The buffer portion 46 is layered on the reinforcing portion 47.

Like the buffer portion 46, the reinforcing portion 47 is formed in a generally annular shape in plan view, surrounding the storage pocket 41a formed in the center. The reinforcing portion 47 covers the entire lower surface 46a of the buffer portion 46; in other words, the lower surface 47a of the reinforcing portion 47 occupies the entire surface to be pressed against the polishing pad 5 of the frame 41. The lower surface 46a of the buffer portion 46 and the upper surface 47b of the reinforcing portion 47 are integrated by thermocompression bonding, concave-convex engagement, or the like.

The thicknesses of the buffer portion 46 and the reinforcing portion 47 are set according to the thickness of the workpiece W so that the buffer portion 46 can support the side of the workpiece W. For example, if the thickness of the workpiece W is 200 μm, the thickness of the buffer portion 46 can be set to 250 μm and the thickness of the reinforcing portion 47 to 50 μm. This ensures a gap between the reinforcing portion 47 and the curved outer surface of the workpiece W, even when the workpiece W moves within the storage pocket 41a, preventing the reinforcing portion 47 from coming into contact with the workpiece W. The frame 41 is replaced when it has worn down by a specified margin (e.g., 30 μm).

By providing the buffer portion 46 so that it is exposed to the storage pocket 41a, as shown in Figure 5, even if the workpiece W moves within the storage pocket 41a due to dynamic friction with the polishing pad 5 during CMP polishing and collides with the buffer portion 46, the buffer portion 46 is configured to gently receive the workpiece W.

In addition, because the reinforcing portion 47 covers the entire underside 46a of the buffer portion 46, even if the frame 41 is pressed against the polishing pad 5 with a pressure corresponding to the air pressure, as shown in Figure 5, the reinforcing portion 47 is interposed between the buffer portion 46 and the polishing pad 5, preventing the buffer portion 46 from wearing down due to dynamic friction.

As shown in FIG. 4 , the frame 41 further includes a warpage suppression section 48. Like the buffer section 46 and the reinforcing section 47, the warpage suppression section 48 is formed in a generally annular shape in plan view, surrounding the centrally formed storage pocket 41a. The warpage suppression section 48 is layered on the buffer section 46 and covers the upper surface 46b of the buffer section 46. The upper surface 46b of the buffer section 46 and the lower surface 48a of the warpage suppression section 48 are integrated by thermocompression bonding, concave-convex engagement, or other methods. The warpage suppression section 48 is made of a material that exhibits higher rigidity than the buffer section 46, such as CFRP. Furthermore, if the same material as the reinforcing section 47 is used for the warpage suppression section 48, it is preferable that the thickness of the warpage suppression section 48 be set to be generally the same as that of the reinforcing section 47. The shape, material, thickness, and other aspects of the warpage suppression section 48 may be adjusted as appropriate within a range that can suppress warpage of the buffer section 46 during CMP polishing.

In this way, the CMP apparatus 1 according to this embodiment is a CMP apparatus 1 for polishing a workpiece, and includes a frame 41 formed with a storage pocket 41a for storing the workpiece W, and pressed against the polishing pad 5 together with the workpiece W. The frame 41 is configured to include a buffer section 46 surrounding the storage pocket 41a, and a reinforcing section 47 integral with the buffer section 46, having higher wear resistance than the buffer section 46, and occupying at least a portion of the pressed surface of the frame 41 that is pressed against the polishing pad 5.

With this configuration, the reinforcing portion 47, which has higher wear resistance than the buffer portion 46, is pressed against the polishing pad 5 instead of the buffer portion 46, thereby suppressing wear on the frame body 41 and reducing the frequency of frame body 41 replacement, thereby extending the operating time of the CMP apparatus 1. Furthermore, because the buffer portion 46 receives the workpiece W moving within the storage pocket 41a during polishing, chipping of the workpiece W during polishing can be suppressed.

In addition, the CMP apparatus 1 according to this embodiment is configured so that the reinforcing portion 47 covers the lower surface 46a of the buffer portion 46.

With this configuration, the reinforcing portion 47 is interposed between the polishing pad 5 and the buffer portion 46, which reduces wear on the buffer portion 46 and further reduces the frequency of replacement of the frame body 41.

The CMP apparatus 1 according to this embodiment also includes a warpage suppression section 48 that covers the upper surface 46b of the buffer section 46, has higher rigidity than the buffer section 46, and suppresses warpage of the buffer section 46.

With this configuration, the buffer portion 46 is sandwiched between the highly rigid reinforcing portion 47 and the warp suppression portion 48, preventing the soft buffer portion 46 from warping during polishing.

Next, a modified example of this embodiment will be described with reference to Figure 6. Note that this modified example differs from the embodiment described above in the configuration of the frame body 41. The configuration other than that described below is the same as the configuration of the embodiment described above.

In the CMP apparatus 1 according to this modified example, as shown in FIG. 6(a), the buffer portion 46 and the reinforcing portion 47 are each formed in a roughly concentric ring shape centered on the storage pocket 41a.

The buffer portion 46 is formed in a generally annular shape in plan view, surrounding the storage pocket 41a formed in the center. The buffer portion 46 is exposed to the storage pocket 41a.

The reinforcing portion 47 is provided on the outer periphery of the buffer portion 46. The outer periphery 46c of the buffer portion 46 and the inner periphery 47c of the reinforcing portion 47 are integrated by thermocompression bonding, concave-convex engagement, or the like. The lower surface 47a of the reinforcing portion 47 occupies a portion of the outer periphery of the pressed surface of the frame 41 that is pressed against the polishing pad 5.

The thicknesses of the buffer portion 46 and the reinforcing portion 47 are set to approximately the same thickness and are set according to the thickness of the workpiece W so that the buffer portion 46 supports the side of the workpiece W. For example, when polishing a workpiece W with a thickness of 200 μm, the thicknesses of the buffer portion 46 and the reinforcing portion 47 are each set to 350 μm.

By providing the buffer section 46 so that it is exposed to the storage pocket 41a, as shown in Figure 6(b), even if the workpiece W moves within the storage pocket 41a due to dynamic friction with the polishing pad 5 caused by a pressing force corresponding to the air pressure and collides with the buffer section 46, the buffer section 46 is configured to gently receive the workpiece W.

In addition, the lower surface 47a of the reinforcing portion 47 occupies a portion of the outer periphery of the pressed surface of the frame 41 that is pressed against the polishing pad 5. Therefore, when the frame 41 is pressed against the polishing pad 5 during CMP polishing, the lower surface 46a of the buffer portion 46 and the lower surface 47a of the reinforcing portion 47 each come into contact with the polishing pad 5.

In this way, the CMP apparatus 1 according to this modified example is configured so that the buffer portion 46 is positioned on the inner periphery of the reinforcing portion 47 and can come into contact with the polishing pad 5.

With this configuration, the reinforcement portion 47 accounts for a portion of the surface of the frame 41 that is pressed against the polishing pad 5, thereby reducing wear on the frame 41 and reducing the frequency of replacement of the frame 41, thereby extending the operating time of the CMP apparatus 1. Furthermore, because the buffer portion 46 receives the workpiece W that moves within the storage pocket 41a during polishing, chipping of the workpiece W during polishing can be reduced.

Furthermore, the present invention can be modified in various ways other than those described above without departing from the spirit of the present invention, and it goes without saying that the present invention also covers such modifications.

In other words, the CMP apparatus 1 according to the present invention may have any configuration as long as it includes a buffer portion 46 that receives the workpiece W moving within the storage pocket 41a during polishing, and a reinforcing portion 47 that is integral with the buffer portion 46, has higher abrasion resistance than the buffer portion 46, and occupies at least a portion of the pressed surface of the frame body 41.

DESCRIPTION OF SYMBOLS 1: CMP apparatus 2: Platen 3: Rotating shaft 4: Motor 5: Polishing pad 10: Polishing head 10a: Rotating shaft 20: Head body 21: Rotating section 30: Carrier 30a: Lower surface 31: Carrier pressing means 32: Air line 34: Replacement section 40: Retainer ring 41: Frame body 41a: Storage pocket 42: Snap ring 43: Retainer pressing member 44: Retainer pressing means 46: Cushioning section 46a: (Cushioning section) Lower surface 46b: (Cushioning section) Upper surface 46c: Outer surface 47: Reinforcing section 47a: (Reinforcing section) Lower surface 47b: (Reinforcing section) Upper surface 47c: Inner surface 48: Warp suppressing section 48a: (Warp suppressing section) Lower surface 50: Membrane film 60: Backing film A: Air chamber W: Work

Claims (2)

A CMP apparatus for polishing a workpiece,
a frame body formed with a storage pocket for storing the workpiece and pressed against the polishing pad together with the workpiece;
The frame body is
a buffer portion provided surrounding the storage pocket;
a reinforcing portion that is integral with the buffer portion, has higher wear resistance than the buffer portion, covers the entire lower surface of the buffer portion, and occupies at least a part of the pressed surface of the frame that is pressed against the polishing pad;
A CMP apparatus comprising: 2. The CMP apparatus according to claim 1 , further comprising a warpage suppression section that covers an upper surface of the buffer section, has higher rigidity than the buffer section, and suppresses warpage of the buffer section.