CN112548848A

CN112548848A - Bearing head and chemical mechanical polishing equipment

Info

Publication number: CN112548848A
Application number: CN201910917838.XA
Authority: CN
Inventors: 赵德文; 刘远航; 路新春
Original assignee: Tsinghua University
Current assignee: Tsinghua University
Priority date: 2019-09-26
Filing date: 2019-09-26
Publication date: 2021-03-26
Anticipated expiration: 2039-09-26
Also published as: CN112548848B

Abstract

The invention discloses a bearing head, which comprises a bearing disc, a flexible membrane, an annular pressure plate, a retaining ring and at least one flexible membrane fixing ring, wherein the flexible membrane is fixed on the bearing disc; the flexible membrane is provided with an edge corrugated wall and at least one inner corrugated wall, and the edge corrugated wall and the inner corrugated wall are clamped to the bearing plate by the annular pressing plate to form a pressure-adjustable chamber; the retaining ring is coupled to the underside of the carrier platter and surrounds the flexible membrane retaining ring; the flexible film fixing ring is clamped at the outer side and/or the inner side of the edge corrugated wall so as to hold the edge corrugated wall; the flexible membrane fixing ring and the retaining ring are respectively provided with magnetic motive parts, so that the circumferential edge of the flexible membrane can be pressed downwards in a controlled manner.

Description

Bearing head and chemical mechanical polishing equipment

Technical Field

The invention relates to the technical field of chemical mechanical polishing, in particular to a bearing head for chemical mechanical polishing and chemical mechanical polishing equipment.

Background

Chemical mechanical polishing is a mainstream method for polishing substrates in the field of chip manufacturing. The polishing method generally attracts and holds the substrate at the lower part of the carrier head, one surface of the substrate with a deposition layer abuts against the rotating polishing pad, and the carrier head rotates in the same direction with the polishing pad under the driving of the driving part and gives a downward load to the substrate; meanwhile, the polishing solution is supplied to the upper surface of the polishing pad and distributed between the substrate and the polishing pad, so that the substrate is subjected to global polishing under the combined action of chemistry and machinery.

The carrier head is an important component of the chemical mechanical polishing apparatus, and the operation performance of the carrier head is directly related to the chemical mechanical polishing effect of the substrate. For example, US20130065495a1 discloses a carrier head, which comprises a carrier tray and an elastic membrane, wherein the elastic membrane is detachably arranged at the lower part of the carrier tray; the carrier tray includes a first portion and a second portion, the first portion being movably disposed concentrically within an upper recess of the second portion such that the first portion and the second portion are movable relative to each other in a direction perpendicular to a bottom surface of the carrier tray. An elastic membrane is arranged at the lower part of the second part, so that a plurality of air cavities are formed between the second part and the elastic membrane, and the pressure profile of the substrate can be adjusted by adjusting the pressure of each independent air cavity. In the prior art, external air enters the channel inside the first part through the air holes on the upper surface of the first part and flows out from the air holes on the side wall of the first part, and then is conveyed to the air holes on the upper surface of the second part which are respectively communicated with the independent air cavities through the air pipes.

Chinese patent CN104854680B discloses a carrier head which can clamp the tail end of each baffle between clamping plates. The various splints may be substantially pure plastic such as polyetheretherketone or polyphenylene sulfide, composite plastic such as glass-filled PEEK or glass-filled PPS, or metal such as stainless steel or aluminum. The gimbal mechanism allows the base assembly to slide vertically relative to the housing while limiting lateral movement of the base assembly. The cover is made of, for example, a semi-crystalline thermoplastic polyester based on polyethylene terephthalate, for example polyester, which can be coated on the outside of the base assembly to prevent contamination from the slurry from reaching the interior of the carrier head.

However, as the feature size of electronic devices continues to shrink, the process requirements for Chemical Mechanical Polishing (CMP) are becoming higher and higher during the fabrication process, resulting in more and more gas chamber partitions in the carrier head. The structure of the bearing head is gradually complicated, the number and the combination relation of parts reach the unprecedented complexity, the challenges are brought to the assembly operation and the maintenance operation, and the high precision requirement and the cost requirement are provided for the part processing; in addition, the detection accuracy requirement of the chemical mechanical polishing end point detection is also improved along with the continuous reduction of the size of the characteristic structure, so a certain requirement is also put forward on the whole electromagnetic signal reflection performance of the bearing head, and the electromagnetic measurement signals are hopefully reflected by other metal parts on the bearing head as few as possible when the characteristic thickness of the metal structure on the substrate is measured; moreover, the carrier head is required to rapidly pick and place the substrate and reduce the possible influence on the substrate in the process of pressurizing the substrate, so as to prevent the substrate from being damaged and the like; further, in the prior art, the two or three gas chambers and/or the recesses and/or the snap rings are disposed at the edge of the flexible film to precisely control the pressure at the edge region of the wafer, which has the problems of high cost, difficulty in manufacturing, easiness in adsorbing pollutants to affect the yield, and the like.

Disclosure of Invention

The embodiment of the invention provides a bearing head for chemical mechanical polishing and chemical mechanical polishing equipment, and aims to solve at least one technical problem in the prior art to a certain extent.

A carrier head for chemical mechanical polishing includes a carrier disk, a flexible membrane, an annular platen, a retaining ring, and at least one flexible membrane retaining ring; the flexible membrane is provided with an edge corrugated wall and at least one inner corrugated wall, and the edge corrugated wall and the inner corrugated wall are clamped to the bearing plate by the annular pressing plate to form a pressure-adjustable chamber; the retaining ring is coupled to the underside of the carrier platter and surrounds the flexible membrane retaining ring; the flexible film fixing ring is clamped at the outer side and/or the inner side of the edge corrugated wall so as to hold the edge corrugated wall; the flexible membrane fixing ring and the retaining ring are respectively provided with magnetic motive parts, so that the circumferential edge of the flexible membrane can be pressed downwards in a controlled manner.

Preferably, the carrier head top is provided with a slip ring, and the coil is electrically connected to the slip ring and electrically connected to an external circuit through the slip ring.

Preferably, a battery and a wireless control module are arranged in the bearing plate, the coil is electrically connected to the wireless control module, and the wireless control module is powered by the battery.

Preferably, the wireless control module is controlled in at least one of bluetooth, radio frequency identification, near field communication, ZigBee or other short-range wireless control modes.

Preferably, a charging module is connected between the battery and the coil, so that the battery can be charged in a wireless charging mode.

Preferably, the flexible film fixing ring comprises a flexible film outer ring and a flexible film inner ring which are clamped on the outer side and the inner side of the edge corrugated wall respectively.

Preferably, the projection of the coil on the vertical plane coincides with the projection of the outer ring of the flexible membrane on the vertical plane.

Preferably, the inner circumferential wall of the retaining ring is non-metallic.

Preferably, the outer ring of the flexible membrane is made of engineering plastics with a permanent magnet embedded therein, and the retaining ring is embedded with a coil.

Meanwhile, the invention also discloses chemical mechanical polishing equipment which comprises the bearing head.

Drawings

The advantages of the invention will become clearer and more readily appreciated from the detailed description given with reference to the following drawings, which are given by way of illustration only and do not limit the scope of protection of the invention, wherein:

FIG. 1 is a schematic diagram of a carrier head for chemical mechanical polishing according to the present invention;

FIG. 2 is a partial schematic view according to one embodiment of the invention;

FIG. 3 is a schematic diagram in accordance with the principles of the present invention;

FIG. 4 is a partial schematic view of another embodiment according to the present invention;

FIG. 5 is a schematic diagram of a structure according to another embodiment of the present invention;

FIG. 6 is a partial schematic view of another embodiment according to the present invention;

FIG. 7 is a partial schematic view of another embodiment according to the present invention;

FIG. 8 is a partial schematic view of another embodiment according to the present invention;

FIG. 9 is a partial schematic view of another embodiment according to the present invention;

FIG. 10 is a partial schematic view of another embodiment according to the present invention;

FIG. 11 is a partial schematic view of another embodiment according to the present invention;

fig. 12 is a partial schematic view of another embodiment according to the present invention.

Detailed Description

The technical solution of the present invention will be described in detail with reference to the following embodiments and accompanying drawings. The embodiments described herein are specific embodiments of the present invention for the purpose of illustrating the concepts of the invention; the description is intended to be illustrative and exemplary and should not be taken to limit the scope of the invention. In addition to the embodiments described herein, those skilled in the art will be able to employ other technical solutions which are obvious based on the disclosure of the claims and the specification thereof, and these technical solutions include technical solutions which make any obvious replacement or modification of the embodiments described herein.

One embodiment of a carrier head 1 for chemical mechanical polishing according to the present invention is shown in fig. 1, and includes a balance 11, a coupling disk 12, a carrier disk 13, a flexible membrane 14, an annular platen 15, and a retaining ring 16; the first clamp ring 20 clamp-couples the outer edge of the annular elastic membrane 21 to the carrier disc 13 and the second clamp ring 23 clamp-couples the inner edge of the annular elastic membrane 21 to the coupling disc 12 so that the coupling disc 12 can bring the carrier disc 13 to coaxially rotate together via the annular elastic membrane 21 when the coupling disc 12 rotates together with an external drive shaft (not shown); the third clamping ring 18 and the

annular gaskets

17A, 17B clamp the balance frame 11 to the carrier plate 13, and the annular pressure plate 15 hermetically clamps the flexible membrane 14 to the lower part of the carrier plate 13 so that the flexible membrane 14 can coaxially rotate with the carrier plate 13 and the balance frame 11 and move up and down in the vertical direction relative to the coupling plate 12; the retaining ring 16 is coupled to the lower surface of the carrier plate 13; when the carrier head 1 is in operation, the coupling disc 12 is coupled to an external drive shaft, and the substrate to be processed is received and held under the flexible membrane 14 inside the retaining ring 16.

The flexible membrane 14 functions to cooperate with the rest of the carrier head 1 to form at least two pressure-adjustable gas chambers to further fine tune the pressure profile applied to the substrate to improve the uniformity and consistency of the chemical mechanical polishing. To this end, the flexible membrane 14 is formed to consist of a circular bottom plate portion, an annular edge corrugation and at least one annular inner corrugation. The edge crush wall and at least one inner crush wall are clamped to the carrier plate 13 by the annular platen 15 to form a pressure adjustable chamber so that the pressure applied to the substrate can be adjusted by controlling the vertical position of the gimbal 11 and the pressure of the pressure adjustable chamber.

As shown in fig. 2, the edge corrugated wall of the flexible film 14 is engaged with at least one flexible film fixing ring, the flexible film fixing ring engaged with the outer side of the edge corrugated wall is referred to as a flexible film outer ring 141, the flexible film fixing ring engaged with the inner side of the edge corrugated wall is referred to as a flexible film inner ring 142, and the edge corrugated wall can be held between the flexible film outer ring 141 and the flexible film inner ring 142 together, or only one of the two can be used to hold the edge corrugated wall.

In an embodiment of the present invention, an annular groove is provided outside the edge corrugated wall of the flexible film 14, and the flexible film outer ring 141 with a contour matching the annular groove is clamped in the annular groove. The inner side of the edge corrugated wall of the flexible membrane 14 and the outer side of the inner ring 142 of the flexible membrane are provided with matched concave-convex structures. When the flexible film outer ring 141 and the flexible film inner ring 142 are respectively clamped on the outer side and the inner side of the flexible film edge corrugated wall, the flexible film edge corrugated wall between the two rings has better rigidity.

The retaining ring 16 may be partially or completely made of engineering plastics, and the flexible film outer ring 141 may be partially or completely made of permanent magnetic materials. The portion of the inner peripheral wall of the retainer ring 16 opposite to the flexible film outer ring 141 has an annular cavity in which the coil 161 is mounted. The coil 161 is coaxial with the flexible membrane outer ring 141, which constitutes a voice coil motor.

As shown in fig. 3, when a current passes through the coil 161, a magnetic field in a vertical direction is generated, and the outer ring 141 of the flexible film containing the permanent magnetic material is subjected to a magnetic force in the vertical direction in the magnetic field, the magnitude and direction of the magnetic force depend on the magnitude and direction of the current in the coil 161, and the magnetic force can generate a pressing or lifting effect on the edge corrugated wall, so as to change the pressing force applied to the substrate by the edge portion of the flexible film. Under the condition that the air pressure of each pressure regulating chamber is kept unchanged, the fine adjustment of the edge pressure of the substrate can be realized by adjusting the current in the coil 161, and further the fine adjustment of the material removal rate of the edge of the substrate is realized.

In another embodiment of the present invention, to ensure the magnetic force control effect, the geometric center of the coil 161 and the geometric center of the outer ring 141 of the flexible film are located at the same height, so that the projection of the coil 161 on the vertical plane coincides with the projection of the outer ring 141 of the flexible film on the vertical plane. The part of the inner peripheral wall of the retaining ring 16, which is located between the coil 161 and the flexible film outer ring 141, is made of a non-metallic material, so as to avoid interference on the magnetic field of the coil.

In another embodiment of the present invention, as shown in fig. 4, the outer flexible membrane ring is eliminated and the inner flexible membrane ring 142 may be partially or completely made of permanent magnetic material. The portion of the inner peripheral wall of the retainer ring 16 opposite to the flexible film outer ring 141 has an annular cavity in which the coil 161 is mounted. The coil 161 and the outer ring 141 of the flexible film are coaxial, the coil 161 and the outer ring 141 of the flexible film form a voice coil motor, when current passes through the coil 161, a magnetic field in the vertical direction is generated, the inner ring 142 of the flexible film with magnetism receives magnetic force in the vertical direction in the magnetic field, the magnitude and the direction of the magnetic force depend on the magnitude and the direction of the current in the coil 161, the magnetic force can generate a pressing-down effect or a lifting-up effect on the edge corrugated wall, and then the pressing-down force applied to the substrate by the edge part of the flexible film is changed. Under the condition that the air pressure of each pressure regulating chamber is kept unchanged, the fine adjustment of the edge pressure of the substrate can be realized by adjusting the current in the coil 161, and further the fine adjustment of the material removal rate of the edge of the substrate is realized. It should be noted that, although not shown in the drawings, the flexible film inner ring 142 may be disposed inside the flexible film circumferential wall by being snap-fitted.

In another embodiment of the present invention, in order to ensure the magnetic force control effect, the geometric center of the coil 161 and the geometric center of the flexible film inner ring 142 are located at the same height, so that the projection of the coil 161 on the vertical plane coincides with the projection of the flexible film inner ring 142 on the vertical plane. The part of the inner peripheral wall of the retaining ring 16 between the coil 161 and the flexible film inner ring 142 is made of non-metallic materials, so as to avoid interference on the magnetic field of the coil.

In another embodiment of the present invention, a slip ring is disposed on the top of the carrier head 1, a conducting wire is disposed inside the carrier head 1, and the coil 161 is electrically connected to the slip ring through the conducting wire and electrically connected to an external circuit through the slip ring. The external circuit can adjust the magnitude and direction of the current in the coil 161 in real time according to the thickness of the material and the removal rate of the edge portion of the substrate, so as to realize the precise adjustment of the edge pressure of the substrate.

As shown in fig. 5, in another embodiment of the present invention, there is no electrical connection between the carrier head 1 and the rest of the chemical mechanical polishing apparatus, a battery 131 and a wireless control module 132 are disposed in the carrier tray 13, the wireless control module 132 adopts a short-distance wireless control manner such as bluetooth, radio frequency identification, near field communication, ZigBee, etc., and is electrically connected to the coil 161, and can adjust the current in the coil 161 in real time according to an external control signal, so as to adjust the edge pressure of the substrate, and both the coil 161 and the wireless control module 132 are powered by the battery 131.

In this embodiment, a charging module 133 is further provided in the carrier tray 13, and the charging module 133 is electrically connected to the coil 161 and the battery 131. When the carrier head 1 is not performing polishing work, the coil 161 can be used as a wireless charging coil to receive power supplied by an external charging device, and the battery 131 is charged via the charging module 133.

In another embodiment of the present invention, the wireless control module 132 is connected to the acceleration sensor to determine whether the carrier head 1 is in a moving state, if the carrier head 1 is in the moving state, the battery 131 continues to provide power, and if the carrier head 1 stops moving, the wireless control module 132 can be disconnected from the battery 131 to save power.

As shown in fig. 6, the flexible film outer ring 141 may adopt a structure in which the outer casing 141B wraps the permanent magnet 141A, and the outer casing 141B is made of a high-strength material, so as to protect the permanent magnet 141A with weak mechanical strength, and to avoid particles generated by damage of the flexible film outer ring 141 in the polishing process as much as possible.

More specifically, the outer casing 141B is a composite plastic, and the permanent magnet 141A is a neodymium iron boron material.

Since the retaining ring 16 is a consumable item, the coil 161 may be of a detachable design to reduce the cost of use. In another embodiment of the present invention, as shown in fig. 7, the coil 161 is embedded in the coil holder 162, the coil holder 162 is detachably coupled to the retaining ring 16, and when the retaining ring is replaced, the coil holder 162 can be removed from the old retaining ring and installed in a new retaining ring for recycling.

More specifically, the coil holder 162 is nylon plastic.

As shown in fig. 8, in another embodiment of the present invention, the coil 161 has a cylindrical shape embedded in the coil holder 162 and is disposed near the inner peripheral wall surface of the coil holder 162. The coil 161 is formed by coaxially winding a plurality of turns of wire, which is coated with an insulating resin such as an enamel resin. The wire is wound in a direction parallel to the lower surface of the carrier tray.

More specifically, the coil 161 is formed with a plurality of layers in the vertical direction, and preferably, an odd number of layers of three or more layers may be formed in the radial direction. In the present embodiment, the coil 161 includes a first coil layer, a second coil layer, and a third coil layer, and is formed by winding an electric wire insulated by an enamel resin on a bobbin, or winding the electric wire in a cylindrical shape and fixing it to the bobbin using an adhesive.

In this embodiment, the magnetization direction of the permanent magnet is axial.

As shown in fig. 9, an annular second permanent magnet 163 is disposed outside the coil 161, and the magnetization directions of the second permanent magnet 163 and the permanent magnet in the flexible film outer ring 141 are both axial and opposite in polarity. Due to the guidance of the second permanent magnet 163, the magnetic lines of force of the permanent magnet in the outer ring 141 of the flexible film extend in the radial direction and pass through the coil 161 to increase the magnetic flux density in the air gap, so that the magnetic flux is fully utilized, the leakage flux is reduced, and the thrust of the voice coil motor under the same driving current is larger.

More specifically, the second permanent magnet 163 employs a neodymium iron boron permanent magnet.

As shown in fig. 10, the second permanent magnet 163 and the permanent magnets in the flexible film outer ring 141 are formed by splicing a plurality of tile-shaped permanent magnets, the magnetization direction of each tile-shaped permanent magnet is axial, a uniform axial magnetic field is formed after splicing, and the tile-shaped magnetic steel group is used to replace an annular permanent magnet, so that the magnetic flux utilization rate can be further improved.

As shown in fig. 11, the coil holder 162 and the flexible film outer ring 141 have annular cavities therein for accommodating a ring-shaped permanent magnet formed by splicing a plurality of tile-shaped permanent magnets.

As shown in fig. 12, in another embodiment of the present invention, the coil 161 is composed of a plurality of sub-coils 161A symmetrically distributed in the retaining ring 16, the sub-coils 161A may be connected in series or may be independent of each other, and the axis of each sub-coil 161A may be maintained in the vertical direction or may form a certain angle with the vertical direction.

The drawings in the present specification are schematic views to assist in explaining the concept of the present invention, and schematically show the shapes of respective portions and their mutual relationships. It should be understood that the drawings are not necessarily to scale, the same reference numerals being used to identify the same elements in the drawings in order to clearly show the structure of the elements of the embodiments of the invention. In the description herein, references to the description of the term "one embodiment," "some embodiments," "an illustrative embodiment," "an example," "a specific example," or "some examples" or the like mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above do not necessarily refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

While embodiments of the invention have been shown and described, it will be understood by those of ordinary skill in the art that: various changes, modifications, substitutions and alterations can be made to the embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the claims and their equivalents.

Claims

1. A carrier head for chemical mechanical polishing comprising a carrier disk, a flexible membrane, an annular platen, a retaining ring, and at least one flexible membrane retaining ring;

the flexible membrane is provided with an edge corrugated wall and at least one inner corrugated wall, and the edge corrugated wall and the inner corrugated wall are clamped to the bearing plate by the annular pressing plate to form a pressure-adjustable chamber;

the retaining ring is coupled to the underside of the carrier platter and surrounds the flexible membrane retaining ring;

the flexible film fixing ring is clamped at the outer side and/or the inner side of the edge corrugated wall so as to hold the edge corrugated wall;

the flexible membrane fixing ring and the retaining ring are respectively provided with magnetic motive parts, so that the circumferential edge of the flexible membrane can be pressed downwards in a controlled manner.

2. The carrier head of claim 1, wherein a slip ring is disposed on the carrier head top, the coil being electrically connected to the slip ring and to external circuitry through the slip ring.

3. The carrier head of claim 1, wherein a battery and a wireless control module are disposed in the carrier platter, the coil being electrically connected to the wireless control module, the wireless control module being powered by the battery.

4. The carrier head of claim 3, wherein the wireless control module is controlled by at least one of Bluetooth, RFID, NFC, ZigBee or other short-range wireless control.

5. The carrier head of claim 4, wherein a charging module is coupled between the battery and the coil such that the battery can be charged by wireless charging.

6. The carrier head of claim 1, wherein the flexible membrane retaining ring comprises a flexible membrane outer ring and a flexible membrane inner ring that snap onto the outer and inner sides of the edge corrugation.

7. The carrier head of claim 6, wherein a projection of the coil in a vertical plane coincides with a projection of the flexible membrane outer ring in a vertical plane.

8. The carrier head of claim 7, wherein the inner circumferential wall of the retaining ring is non-metallic.

9. The carrier head of any of claims 6-8, wherein the outer flexible membrane ring is an engineering plastic with permanent magnets embedded therein, and wherein the retaining ring has coils embedded therein.

10. A chemical mechanical polishing apparatus comprising a carrier head according to any of claims 1-9.