TW201632307A - Systems, apparatus, and methods for an improved polishing head gimbal using a spherical ball bearing - Google Patents

Abstract

Embodiments of the present invention provide systems, apparatus, and methods for an improved polishing head including an upper portion and a lower portion, the lower portion adapted to hold a substrate and to tilt relative to the upper portion, the tilt enabled by a spherical bearing, wherein the lower portion is adapted to tilt while rotating the substrate against a rotating polishing pad so that the lower portion remains flush against the rotating polishing pad while resisting lateral friction force generated by the rotating polishing pad contacting the substrate and pushing the substrate laterally against the lower portion. Numerous additional aspects are disclosed.

Description

System and device for improved polishing head balance ring using spherical ball bearing method [related application]

This application claims to apply to the system, apparatus and method for the improved polishing head balance ring using spherical ball bearings on February 17, 2015 (SYSTEMS, APPARATUS, AND METHODS FOR AN IMPROVED POLISHING HEAD GIMBAL USING A SPHERICAL BALL BEARING), US Patent No. 14/624,197 (Attorney Docket No. 20709/USA), which also claims to apply for the improvement of the use of spherical ball bearings on December 19, 2014. U.S. Provisional Patent Application No. 62/094,414 (Attorney Docket No. 20709/USA/), System, Apparatus and Method for Polishing Head Balance Ring (SYSTEMS, APPARATUS, AND METHODS FOR AN IMPROVED POLISHING HEAD GIMBAL USING A SPHERICAL BALL BEARING) The priority of L) is hereby incorporated by reference in its entirety for all purposes.

The present invention relates to chemical mechanical planarization (CMP) polishing heads, and more particularly to systems, devices and methods for improved polishing head balance rings using spherical ball bearings.

A semiconductor substrate is a basic material in the production of a semiconductor element. Semiconductor components exist in many different and very common products and components, including PCs, cellular phones and other IT devices, digital cameras, TVs and other digital consumer electronics, and automotive control systems. The evolution of semiconductor components has enriched human life by providing convenience and comfort.

The history of semiconductor components involves repeated improvements in packing density, efficiency, and economic rationality. Advances in larger semiconductor substrates have made an important contribution to this advancement. For example, a larger substrate diameter makes it possible to produce more semiconductor components with a single substrate. This means considerable productivity and economic efficiency.

In the past 50 years, semiconductor substrates have been gradually and steadily increasing, from 100mm, 150mm and 200mm germanium substrates to the current 300mm diameter substrates. The historical reasons for this substrate size increase are based on three related trends: increased wafer size, increased wafer demand, and greater wafer throughput (and thus lower wafer cost), which can be achieved with larger substrate sizes. In addition, although the size of the wafer has been substantially stable, the other two factors are still compelling. Each of the first two substrate size transitions (150mm to 200mm and 200mm to 300mm) Sub-transitions result in a reduction in unit area cost (and thus unit wafer cost) by approximately 30%. In the next stage, the feasibility of increasing the substrate size to 450 mm is under study.

As the substrate size increases, the surface area to be planarized using a chemical mechanical planarization (CMP) method increases. The increased surface area results in higher lateral friction being applied to the components within the CMP system. In particular, the balance ring used in the CMP polishing head carries an increased load due to the higher lateral friction of the larger substrate. Thus, there is a need for an improved system, apparatus and method for manageable increased friction of a polishing head balance ring.

In some embodiments, the present invention provides a system for chemical mechanical planarization. The system includes: a platform supporting a polishing pad and adapted to rotate the polishing pad; and a polishing head calibrated to rotate and including an upper portion and a lower portion, the lower portion being tuned to hold the substrate and tilted relative to the upper portion, the slope It is energized by a ball bearing. The lower portion is adapted to tilt while rotating the substrate against the polishing pad such that the lower portion is flush with the rotating polishing pad while resisting lateral friction generated by the rotating polishing pad contacting the substrate and pushing the substrate laterally against the lower portion .

In some other embodiments, the present invention provides a chemical mechanical planarization polishing head. The polishing head includes an upper portion and a lower portion that are tuned to hold the substrate and tilt relative to the upper portion, the tilt being energized by the ball bearing. The lower portion is adapted to tilt while rotating the substrate against the rotating polishing pad such that the lower portion is flush with the rotating polishing pad, At the same time, it resists the lateral friction generated by the rotating polishing pad contacting the substrate and pushing the substrate laterally against the lower portion.

In still other embodiments, the present invention provides a method of chemical mechanical planarization. The method includes providing a polishing head including an upper portion and a lower portion, the lower portion being tuned to hold the substrate and inclined relative to the upper portion, the inclination being energized by the ball bearing; rotating the polishing head while holding the substrate to resist Moving the polishing pad; and tilting the lower portion while rotating the substrate against the polishing pad such that the lower portion is flush with the moving polishing pad while resisting the contact of the substrate by the moving polishing pad and pushing the substrate laterally against the lower portion Lateral friction.

The invention will be described in the following detailed description, the appended claims, and the accompanying drawings, Still other features, aspects, and advantages of the embodiments will be more fully apparent. The embodiments of the present invention can be adapted to other and different applications, and the details of the embodiments may be modified in various aspects without departing from the spirit and scope of the embodiments of the present invention. Accordingly, the drawings and description are to be regarded as The drawings are not necessarily drawn to scale. The description is intended to cover all modifications, equivalents and alternatives of the spirit and scope of the invention.

100‧‧‧Chemical mechanical flattening system

102‧‧‧Substrate

104‧‧‧ polishing head

106‧‧‧arm

108‧‧‧ polishing pad

110‧‧‧Rotating platform

200‧‧‧Previous technical polishing head

202‧‧‧上上

204‧‧‧下下

206‧‧‧Flexing bearings

208‧‧‧ center axis

302‧‧‧ upper part

304‧‧‧ lower part

306‧‧‧Ball bearings

308‧‧‧Axis

310‧‧‧ outer ring

312‧‧‧ internal part

314‧‧‧ buckle

400‧‧‧Sphere ordinary bearing

402‧‧‧ Inner Ring

404‧‧‧Outer Ring

406‧‧‧ Locking features

408‧‧‧ lining

410‧‧‧ ball bearings

412‧‧‧ rolling elements

414‧‧‧ outer ring

416‧‧‧ Inner Ring

500‧‧‧ method

502‧‧‧Steps

504‧‧‧Steps

506‧‧‧Steps

1 is a schematic diagram showing an exemplary chemical mechanical planarization (CMP) system in accordance with an embodiment of the present invention.

Figure 2 is a schematic view showing a polishing head according to the prior art.

Figure 3 is a schematic diagram showing an exemplary polishing head assembly in accordance with an embodiment of the present invention.

4A and 4B are perspective views of two different exemplary ball bearings that are suitable for use in some embodiments of the present invention.

Figure 5 is a flow diagram illustrating an exemplary method of chemical mechanical planarization in accordance with an embodiment of the present invention.

Embodiments of the present invention provide systems, devices, and methods for improved polishing head gimbals using ball-type ball bearings. Prior art gimbal mechanisms within CMP polishing heads typically use flexural bearing designs to accommodate vertical platform bounce. This type of bounce occurs when the platform on which the polishing pad is placed is not completely parallel to the polishing head holding the substrate. While resisting the lateral load caused by the friction during processing, the vertical platform jump is converted to the polishing head tilt. The fatigue limit of the flexural bearing design is approached while adapting to the runout and providing head tilt, and may exceed this fatigue limit when process conditions (eg, such conditions may include larger substrates) result in greater lateral loads. In addition to the geometric optimization of flexure bearing designs, process conditions can require costly material changes. The use of ball bearings instead of flexure bearings as the balance ring of the polishing head allows for free rotation on low friction bearings, which can also withstand the increased lateral loads experienced by the polishing head.

Referring to FIG. 1, a side view of an exemplary chemical mechanical planarization (CMP) system 100 for polishing a substrate 102 is illustrated. The system 100 includes a polishing head 104 supported by an arm 106 that is operable to move the polishing head 104 holding the substrate 102 toward the polishing pad 108 on the rotating platform 110. In operation, the polishing head 104 holds the substrate 102 against the polishing pad 108 to remove material from the substrate 102. As the polishing pad 108 rotates on the platform 110, the polishing head 104 rotates the substrate and pushes the substrate down against the polishing pad 108. As discussed above, the major surface of the platform 110 supporting the polishing pad 108 and the polishing pad 108 may not be completely parallel to the polishing head 104 holding the substrate 102. In the absence of a gimbal to accommodate this bounce (eg, tilt), there may be a gap between the polishing pad 108 and the lower portion of the polishing head 104 that holds the substrate 102, and the substrate 102 may pass from the polishing head 104 via the gap. Slip off.

Please refer to FIG. 2, which shows an example of a prior art polishing head 200. The prior art polishing head 200 includes an upper portion 202 and a lower portion 204. A flexure bearing 206 formed of a semi-rigid flexible material is used to couple the lower portion to a central shaft 208 that is rigidly coupled to the upper portion 202.

The prior art flexure bearing 206 is designed to have sufficient flexibility to accommodate the tilting requirements of prior art polishing heads 200, but also has sufficient rigidity to support a lateral force applied against the polishing pad by pressing the substrate against it. Friction. If the flexure bearing 206 is too flexible, it will not resist the lateral friction load and will immediately collapse and fail. If scratched The curved bearing 206 is not sufficiently flexible, and when a lower downward force is applied to the lower portion, the flexure bearing 206 will not hold the prior art polishing head 200 to be flush with the polishing pad, thereby creating a gap that will allow The substrate slips; in this case, with the high downward force pushing the lower portion flush with the polishing pad, the flexure bearing 206 will fail prematurely due to fatigue. This tradeoff provides a window for the optimal design of the flexure bearing 206. However, with increased lateral friction loads, the design window becomes extremely narrow and the solution, if at all possible, may not be cost effective or feasible. Moreover, the cost of replacing the failed flexure bearing 206 can be high.

Embodiments of the present invention provide an improved gimbal that is capable of accommodating higher lateral friction loads and, in turn, provides low friction free rotation to allow the polishing head to readily accommodate vertical platform bounce. Please refer to FIG. 3, which illustrates an exemplary polishing head 104. The polishing head 104 includes an upper portion 302 and a lower portion 304. The lower portion 304 is coupled to the ball bearing 306 and the ball bearing 306 is coupled to the shaft 308 , which is coupled to the upper portion 302 of the polishing head 104 . More specifically, the lower portion 304 of the polishing head 104 is rigidly coupled to the outer ring 310 of the ball bearing 306, and the shaft 308 coupled to the upper portion 302 of the polishing head 104 is rigidly coupled to the inner portion of the ball bearing 306. 312. The inner portion 312 of the ball bearing 306 is free to tilt within the outer ring 310 of the ball bearing 306.

The ball bearing 306 allows the lower portion 304 of the polishing head 104 to be tilted about the point within the ball bearing 306 relative to the upper portion 302 (as indicated by the dashed curve, the arrows of the imaginary curve pointing to either end of Figure 3). In operation, the base on the bottom of the lower portion 304 of the polishing head 104 The plate 102 is pressed into the polishing pad 108 by an inflatable film (Fig. 1) and held in place on the polishing head 104 by a buckle 314 that surrounds the substrate 102. The buckle 314 is coupled to the outer ring 310 of the ball bearing 306. This allows the buckle 314 to be tilted and allows the lower surface of the buckle 314 to be held flush against the polishing pad 108 (Fig. 1), thereby intercepting the substrate 102.

It should be noted that the tilt of the polishing head 104 energized by the ball bearing 306 does not affect the downward force angle applied to the substrate 102. In contrast, the expandable film within portion 304 of polishing head 104 provides uniform pressure across the back side of substrate 102 to maintain the substrate flush against polishing pad 108. The ball bearing 306 only affects the tilt of the buckle 314. In other words, the angle of the downward force on the substrate 102 does not depend on the angle of the downward force on the buckle 314.

While the ball bearing 306 helps to maintain the buckle 314 flush with the polishing pad 108, lateral friction (as indicated by the marked double-headed arrow in the figure) pushes the substrate 102 against the inner surface of the buckle 314. . Since the buckle 314 is coupled to the ball bearing 306, this lateral force is generated by the ball bearing 306. The ability of the ball bearing 306 to carry a lateral friction load is of the order of magnitude higher than that of the flexure bearing used in prior art polishing head 200 (Fig. 2). For example, it may be difficult to design a flexure bearing suitable for a 300 mm prior art polishing head. It is challenging to load a flexure bearing that can bring 230 pounds of lateral load into the available space. In contrast, commercially available ball bearings, such as model GE17-EC manufactured by IKO Japan Tohoku Co., Ltd., Tokyo, Japan, have a dynamic load capacity of 7,600 pounds. Use significantly larger dynamic load capacity if needed Ball bearings. It has been expected that a 450 mm substrate will only produce a lateral friction load of two to three times the substrate load of 300 mm based on a larger surface area.

In some embodiments, different types of ball bearings 306 can be used. For example, FIG. 4A illustrates an example of a ball-type plain bearing 400 that includes an inner ring 402 having an outer convex annular surface that slides against an inner concave annular surface of the outer ring 404. . The ball plain bearing 400 includes a locking feature 406 that allows the inner ring 402 to be captured within the outer ring 404 only in the axial direction. Inner ring 402 slides against outer ring 404 by the use of a lubricant or a maintenance-free (e.g., polytetrafluoroethylene (PTFE)) liner 408. In some embodiments, the ball bearing 410 as shown in FIG. 4B can incorporate a rolling element 412, such as a ball bearing, between the outer ring 414 and the inner ring 416. It should be noted that the inner ring 416 can be a full spherical body rather than a toroidal body.

Referring again to FIG. 3, in some embodiments, the lower portion 304 of the polishing head 104 can be coupled to the outer ring 310 of the ball bearing 306, as shown, or in other embodiments, the lower portion 304 can be coupled. It is connected to the inner portion 312 of the ball bearing 306. Also, in some embodiments, the upper portion 302 of the polishing head 104 (via the shaft 308) can be coupled to the inner portion 312 of the ball bearing 306, as shown, or in other embodiments, the upper portion 302 (via The shaft 308) can be coupled to the outer ring 310 of the ball bearing 306.

Referring now to Figure 5, an exemplary method 500 of chemical mechanical planarization (CMP) is illustrated in flow chart form. Initially, a polishing head is provided that includes an upper portion and a lower portion (502). The lower portion is adapted to hold the substrate and includes a buckle that is adapted to tilt relative to the upper portion. The tilting or free rotation is energized by a ball bearing having an inner portion and an outer ring. The inner portion is disposed on a shaft coupled to the upper portion of the polishing head. The outer ring is coupled to the lower portion of the polishing head. In some embodiments, the coupling can be reversed.

Next, the polishing head is rotated while the substrate is held against the moving polishing pad (504). While the substrate is rotating against the polishing pad, the lower portion of the polishing head is tilted or free to rotate such that the lower surface of the buckle remains flush against the moving polishing pad (506). At the same time, the lateral friction generated by the moving polishing pad contacting the substrate and pushing the substrate against the buckle is resisted.

Most of the embodiments are described in this disclosure, and such embodiments are for illustrative purposes only. The examples are not intended to be limiting in any sense. The presently disclosed embodiments of the invention are broadly applicable to a wide variety of applications, as will be apparent from the disclosure. It will be appreciated by those skilled in the art that the disclosed embodiments of the invention can be practiced in various variations and changes, such as structural, logical, and mechanical changes. Although the specific features of the disclosed embodiments of the invention may be described with reference to one or more specific embodiments and/or drawings, it is understood that the features are not limited to the one or More specific embodiments or drawings Way, unless otherwise specified. The present disclosure is not a literal description of all embodiments, nor is it a list of features of the invention that must be present in all embodiments.

The present disclosure provides an enabling description of several embodiments to those of ordinary skill in the art. Some of the embodiments may be claimed in this application, but may still be claimed in one or more of the continuing applications claiming the priority of the present application.

The foregoing description discloses only exemplary embodiments of the invention. Variations on the devices, systems, and methods disclosed above that are within the scope of the invention will be apparent to those skilled in the art.

Accordingly, while the present invention has been described in connection with the exemplary embodiments of the present invention, it is understood that other embodiments may be in accordance with the spirit and scope of the invention, as defined in the following claims.

102‧‧‧Substrate

104‧‧‧ polishing head

302‧‧‧ upper part

304‧‧‧ lower part

306‧‧‧Ball bearings

308‧‧‧Axis

310‧‧‧ outer ring

312‧‧‧ internal part

314‧‧‧ buckle

Claims (20)

A system for chemical mechanical planarization comprising: a platform supporting a polishing pad and adapted to rotate the polishing pad; and a polishing head adapted to rotate and including an upper portion and a lower portion, the lower portion Adapting to hold a substrate and tilting relative to the upper portion, the tilt being energized by a ball bearing, wherein the lower portion is adapted to tilt while rotating the substrate against the polishing pad such that the lower portion remains flat Abutting the rotating polishing pad while resisting the lateral friction generated by the rotating polishing pad contacting the substrate and pushing the substrate laterally against the lower portion. The system of claim 1 wherein the lower portion includes a buckle that is adapted to tilt relative to the upper portion. The system of claim 2, wherein the ball bearing comprises an inner portion and an outer ring. The system of claim 3, wherein the inner portion is disposed on a shaft, the shaft is coupled to the upper portion, and the outer ring is coupled to the lower portion. The system of claim 3, wherein the outer ring is coupled to a shaft, the shaft is coupled to the upper portion, and the inner portion is coupled to the lower portion. The system of claim 3, wherein the lower portion of the system The buckle is adapted to tilt while the substrate is rotated against the polishing pad such that a lower surface of the buckle remains flush against the rotating polishing pad. The system of claim 6 wherein the lateral friction generated by the rotating polishing pad contacting the substrate is resisted by the buckle. A chemical mechanical planarization polishing head comprising: an upper portion and a lower portion adapted to hold a substrate and tilted relative to the upper portion, the tilt being energized by a ball bearing, wherein the lower portion is adapted Inclining while rotating the substrate against a rotating polishing pad such that the lower portion remains flush against the rotating polishing pad while resisting contact with the substrate by the rotating polishing pad and pushing the substrate laterally against the lower portion The resulting lateral friction. The chemical mechanical planarization polishing head of claim 8, wherein the lower portion includes a buckle that is adapted to be inclined relative to the upper portion. The chemical mechanical planarization polishing head of claim 9, wherein the ball bearing comprises an inner portion and an outer ring. The chemical mechanical planarization polishing head of claim 10, wherein the inner portion is disposed on a shaft, the shaft is coupled to the upper portion, and the outer ring is coupled to the lower portion. Chemical mechanical planarization polishing as described in claim 10 a head, wherein the outer ring is coupled to a shaft, the shaft is coupled to the upper portion, and the inner portion is coupled to the lower portion. The chemical mechanical planarization polishing head of claim 10, wherein the lower portion of the buckle is adapted to tilt while the substrate is rotated against the polishing pad such that a lower surface of the buckle remains flush Abut the rotating polishing pad. A chemical mechanical planarization polishing head according to claim 13 wherein the lateral friction generated by the rotary polishing pad contacting the substrate is resisted by the buckle. A method for chemical mechanical planarization comprising: providing a polishing head, the polishing head including an upper portion and a lower portion, the lower portion adapted to hold a substrate and tilt relative to the upper portion, the inclination being a ball Forming a bearing; rotating the polishing head while holding the substrate against a moving polishing pad; and tilting the lower portion while rotating the substrate against the polishing pad such that the lower portion remains flush against the The polishing pad is moved while resisting the lateral friction generated by the moving polishing pad contacting the substrate and pushing the substrate laterally against the lower portion. The method of claim 15, wherein the lower portion includes a buckle that is adapted to tilt relative to the upper portion. The method of claim 16, wherein the spherical shaft The bearing includes an inner part and an outer ring. The method of claim 17, wherein the inner portion is disposed on a shaft, the shaft is coupled to the upper portion, and the outer ring is coupled to the lower portion. The method of claim 17, wherein the outer ring is coupled to a shaft, the shaft is coupled to the upper portion, and the inner portion is coupled to the lower portion. The method of claim 17, wherein the lower portion of the buckle is adapted to tilt while the substrate is rotated against the polishing pad such that a lower surface of the buckle remains flush against the rotating polishing pad Wherein the lateral friction generated by the rotating polishing pad contacting the substrate is resisted by the buckle.