CN110948379B

CN110948379B - Chemical mechanical polishing device

Info

Publication number: CN110948379B
Application number: CN201911015128.4A
Authority: CN
Inventors: 李长坤; 刘远航; 赵德文; 路新春; 曹自立
Original assignee: Tsinghua University; Huahaiqingke Co Ltd
Current assignee: Tsinghua University; Huahaiqingke Co Ltd
Priority date: 2019-10-24
Filing date: 2019-10-24
Publication date: 2020-10-20
Anticipated expiration: 2039-10-24
Also published as: CN110948379A

Abstract

The invention discloses a chemical mechanical polishing device, comprising: a turntable for rotating the polishing pad therewith; a carrier head configured with a retaining ring to receive a substrate and load the substrate onto the polishing pad; the bearing head driving device comprises a motor, a driving shaft, a pneumatic assembly, a shell and a control unit. The motor and the pneumatic assembly are arranged in the shell, the driving shaft extends out of the bottom of the shell to transmit the action of the motor and the pneumatic assembly to the bearing head, the outer surface of the shell is provided with an optical sensor unit and a guide rod for actuating the optical sensor unit, the optical sensor unit can move on the surface of the shell along with the guide rod or move below the shell, and the optical sensor unit is provided with at least one angle-adjustable camera or a plurality of cameras which are arranged in different directions to acquire image information of different working areas and parts of the chemical mechanical polishing device.

Description

Chemical mechanical polishing device

Technical Field

The disclosure relates to the field of semiconductor substrate processing, and in particular relates to chemical mechanical polishing equipment.

Background

Chemical mechanical polishing is a mainstream way of polishing substrates in the field of chip manufacturing. The polishing method generally attracts the substrate to the lower part of the carrier head, the surface of the substrate with the deposition layer abuts against the upper surface of the rotating polishing pad, and the carrier head is driven by the driving part to rotate in the same direction as the polishing pad and apply 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 globally polished under the combined action of chemistry and machinery.

As the characteristic line width of circuits gradually moves from 250nm to 28nm and even to 5nm, the demand for chemical mechanical polishing in substrate manufacturing becomes very high, such as the need for more convenient and reliable real-time monitoring of the surface topography and temperature of the polishing pad, the need for more convenient and reliable real-time monitoring of the dispersion and temperature state of the polishing liquid, the need for more convenient and reliable real-time monitoring of the crystallization of the polishing liquid on the surface of the polishing member such as the retainer ring, the need for more convenient and reliable monitoring of the wear of the polishing pad and the sacrificial portion of the retainer ring, and the like.

Disclosure of Invention

The present invention is directed to solve some of the above problems and, in view of the above, provides a chemical mechanical polishing apparatus comprising:

a turntable for rotating the polishing pad therewith; a carrier head configured with a retaining ring to receive a substrate and load the substrate onto the polishing pad; the bearing head driving device comprises a motor, a driving shaft, a pneumatic assembly, a shell and a control unit. The motor and pneumatic assembly being disposed within the housing, the drive shaft extending from the bottom of the housing to transfer the action of the motor and pneumatic assembly to the carrier head; the outer surface of the shell is provided with an optical sensor unit and a guide rod for actuating the optical sensor unit, the optical sensor unit can move on the surface of the shell along with the guide rod or move below the shell, and the optical sensor unit is provided with at least one angle-adjustable camera or a plurality of cameras which are arranged in different directions so as to acquire image information of different operation areas and parts of the chemical mechanical polishing device.

Preferably, the camera of the optical sensor unit may be rotated 360 degrees in a horizontal direction and/or 180 degrees in a vertical direction.

Preferably, the optical sensor unit is provided with a first camera, a second camera and a third camera, the first camera is arranged upwards at the top of the optical sensor unit to obtain the image of the bottom of the carrier head, the second camera is horizontally arranged on the side surface of the optical sensor unit to obtain the image of the circumferential surface of the carrier head, and the third camera is arranged downwards at the bottom of the optical sensor unit to obtain the image of the surface of the polishing pad.

Preferably, at least one of the cameras is provided with an optical projector to project illumination light and/or structured light towards the viewing field area.

Preferably, the optical sensor unit is movable into proximity with or into contact with a polishing pad to measure the thickness, wear, contamination, and level of photochemistry of the polishing pad.

The invention has the advantages of solving the contradiction between the visual field and the accuracy of the chemical mechanical polishing state monitoring to a certain extent and simultaneously acquiring various state data of different positions of different polishing parts to provide a big data basis for multivariate statistical regression analysis and machine learning, and solving the problem of insufficient training and decision data to a certain extent.

Drawings

In order to further clearly illustrate the embodiments of the present invention and/or the related technical solutions in the prior art, the drawings and the main contents thereof which are needed to be used in the description of the embodiments and the prior art according to the present invention will be briefly described below, it is obvious that the drawings in the following description are only a part of the embodiments of the present invention, and other drawings can be obtained by those skilled in the art without creative efforts according to the provided drawings.

FIG. 1 is a schematic structural view of a chemical mechanical polishing apparatus having two optical sensor units disposed on an outer surface of a driving apparatus for a chemical mechanical polishing carrier head according to the present invention;

FIG. 2 illustrates a chemical mechanical polishing apparatus in which a surface of a driving apparatus of a carrier head is provided with vertical rails and diagonal rails, and an optical sensor unit is movable along the rails therein at an outer surface of the driving apparatus of the carrier head;

FIG. 3 illustrates a chemical mechanical polishing apparatus with an extension rail disposed on an outer surface of a drive of a carrier head, with an optical sensor unit movable with the extension rail to below the drive of the carrier head;

fig. 4A and 4B respectively show variations of optical sensor units of different forms.

Detailed Description

The technical solution of the present invention will be described in detail with reference to the following embodiments and accompanying drawings. The examples described herein are specific embodiments of the present invention and are provided to illustrate the principles of the present 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 and modification to the embodiments described herein.

In the present application, "Chemical Mechanical Polishing" is also referred to as "Chemical Mechanical Planarization", and a substrate (substrate) is also referred to as a wafer (wafer), which means equivalent to the actual function.

In order to explain the technical means of the present invention, the following description will be given by way of specific examples. As shown in fig. 1, the main components of the cmp apparatus to which the carrier head driving apparatus 100 according to the embodiment of the present invention is applied include: a carrier head 10 for holding a substrate and loading an actuated substrate, a polishing platen 20 having an upper surface covered with a polishing pad 21, a dresser 30 for dressing the polishing pad 21, and a liquid supply 40 for supplying a polishing liquid, a carrier head driving device 50 for driving the carrier head 10 to rotate and transmitting a load to the carrier head 10, and a drive shaft 60 for coupling the carrier head 10 and the carrier head driving device 50; wherein a motor (not shown) for rotating the driving shaft 60 and a pneumatic assembly (not shown) for applying a gas load to the carrier head 10, etc. are provided in the carrier head driving device 50, and the carrier head driving device 50 can horizontally move the carrier head 10 along a guide member such as a slide rail, etc. closer to or farther from the circumferential center of the polishing pad 21.

During the chemical mechanical polishing operation, the carrier head 10 presses the substrate received on the lower surface thereof against the polishing pad 21 covered by the surface of the polishing pad 20, and the carrier head 10 performs a rotational motion and a reciprocating motion in the radial direction of the polishing pad 20 so that the surface of the substrate contacting the polishing pad 21 is gradually polished away while the polishing pad 20 rotates, and the liquid supply device 40 spreads and applies the polishing liquid to the surface of the polishing pad 21. Under the combined action of the chemical action of the polishing liquid and the mechanical load of the carrier head, the substrate and the polishing pad 21 are rubbed by the relative motion of the carrier head 10 and the polishing disc 20 to realize the global polishing of the substrate. The dresser 30 serves to dress and activate the topography of the polishing pad 21 during polishing, and foreign particles remaining on the surface of the polishing pad 21, such as polishing particles in a polishing liquid and waste materials detached from the surface of the substrate, can be removed using the dresser 30, and the surface deformation of the polishing pad 21 due to polishing can be planarized.

As shown in fig. 1, the carrier head driving assembly 50 can only move linearly or swing in the horizontal direction and is difficult to move in the vertical direction, the distance between the lowermost end of the housing 501 and the upper surface of the polishing pad 21 is about 60mm to 120mm, and the housing 501 may be formed as a rectangular box extending vertically as shown in fig. 1, or may be formed as a vertical box having an oval or other shape combination in cross section to accommodate other components such as a motor and a pneumatic assembly. The carrier head driving device 50 according to the present invention further comprises an optical sensor unit 502 and/or an optical sensor unit 503 disposed on an outer surface of its housing 501, in other words, at least one optical sensor unit is mounted on a surface of the carrier head driving device 50 according to the present invention. More specifically, for the housing 501 shaped as shown in fig. 1, the

optical sensor units

502, 503 are disposed at the lower edge of the side of the housing 501 closest to the edge of the polishing pad 21, for example, at the middle of the lower edge of the side or at one end and/or both ends of the lower edge. In view of the small distance between the bottom of the housing 501 and the polishing pad 21, and the diameter of the polishing pad 21 is typically 500mm to 770mm, it is difficult to acquire full-field high-definition surface image data of the polishing pad 21 through the

optical sensor units

502 and 503 like the carrier head driving device 50 of the present invention by using the technical solution of mounting a camera only on the lower surface of the structure similar to the housing 501 or the frame of the chemical mechanical polishing apparatus in the prior art, or the carrier head driving device 50 with the optical sensor units according to the present invention can acquire image information of the polishing pad 21 and other components of the polishing apparatus more extensively, more accurately and more comprehensively.

In order to further enlarge the effective field of view (field of view) of the

optical sensor unit

502 or 503 of the carrier head driving apparatus 50, the optical sensor unit 502 and/or 503 may be provided as a movable sensor unit so that the optical sensor unit can be vertically moved on the surface of the housing 501, thereby increasing the distance of the sensor unit from the polishing pad 21 to increase the effective field of view range thereof, which makes it possible to monitor not only the distribution state and flow rate information of the polishing liquid on the surface of the polishing pad 21, etc., but also the working state of the liquid supply means 40 and dresser 30, etc., more comprehensively. Another advantage of locating the optical sensor unit on the outer surface of the housing 501 rather than the bottom surface is that it is desirable to minimize the carrier head 10 from falling within the field of view of the optical sensor unit so that more surface images of the polishing pad 21 are captured, in other words, to minimize the carrier head 10 from blocking the field of view of the optical sensor unit.

As shown in fig. 2, in order to facilitate the movement of the

optical sensor units

502 and 503 on the surface of the housing 501, the surface of the housing 501 may be provided with at least one guide rail 510 extending vertically along a vertical corner edge or a vertical edge of the housing closest to the polishing pad 21, so that the optical sensor unit 503 may be vertically moved by the guide rail 510 to adjust the distance between it and the polishing pad 21; as an alternative variant of the guide 510, it may also be formed, for example, in the form of a guide 520, the guide 520 extending diagonally along the outer surface of the side of the housing 501 at an angle of 30 to 60 degrees, preferably 45 degrees, to the horizontal.

In addition, as shown in fig. 3, in order to enable the optical sensor unit 503 to monitor fine features and the like on the surface of the polishing pad 21 at a close distance, an inner slide rail 530B may be additionally provided and the optical sensor unit 503 may be disposed at a lower end of the inner slide rail 530B, the inner slide rail 530B is movably sleeved in the outer slide rail 530A and may move along the outer slide rail 530A to adjust a distance between the sensor unit 503 and the upper surface of the polishing pad 21, and a dotted line in fig. 3 shows a state after the inner slide rail 530B drives the optical sensor unit 503 to move vertically downward, so that the optical sensor unit 503 is already located close to a plane where the upper surface of the polishing head 10 is located and may continue to move downward until contacting the polishing pad 21.

By vertically moving the optical sensor unit 503 downward along the inner guide rail 530B into contact with the upper surface of the polishing pad 21, the optical sensor unit 503 can facilitate closely monitoring the operational status of the polishing head 10 and the polishing pad 21, such as monitoring the accumulation of crystalline particles on the outer periphery of the carrier head 10, monitoring the surface of the polishing pad 21 for contaminants, particles, impurities, and the like, and/or the thickness and wear of the polishing pad 21.

Although not shown, as a variation of the carrier head driving assembly 50 according to the present invention, an outer slide rail 530A, an inner slide rail 530B, and an optical sensor unit 503 mounted at a lower end of the inner slide rail 530B may also be provided inside the housing 501, and when the optical sensor unit 503 is required to be used, the inner slide rail 530B carries the optical sensor unit 503 to move vertically downward to protrude from the bottom of the housing 501. Similarly, a plurality of similar guide rails may be provided on the outer surface of the housing 501 of the carrier head driving assembly 50, so that a plurality of optical sensor units provided on the surface thereof, the number of which may be 1, 2, 3 or more, are movable along the corresponding guide rails to change the positions thereof, and these

optical sensor units

502 or 503 may be formed to include a camera, a lens group, an angle adjusting portion, etc., so that the camera can change the position and angle of the field of view thereof to acquire image information of different orientations.

In addition, an optical projector (not shown) may be disposed on the outer surface of the housing 501, the optical projector may project infrared light, ultraviolet light, white light, etc. in different forms and patterns, the patterns may be stripe structure light, speckle structure light, etc. to measure the surface topography of the polishing pad 21, the distribution and thickness of the polishing liquid, Bow Wave (Bow Wave) around the polishing head, etc. in cooperation with the camera, and the optical projector may include two or more projection portions to project light in different forms, optical patterns, and combinations thereof, and may be formed as an LED light source, an LCD light source.

It is easy to think that the optical projector can be packaged with the camera head into a whole, become an optical sensor unit and move together, the

optical sensor unit

502, 503 can also be used for monitoring whether the substrate received by the polishing head 10 has the Slip (Wave Slip) phenomenon, the flow rate of the polishing solution on the surface of the polishing pad 21, and the like; preferably, the image sensors of the cameras in the

optical sensor units

502 and 503 are high-speed image sensors with an acquisition rate of more than 500 frames per second, and preferably high-speed image sensors with an acquisition rate of more than 2000 frames per second, so as to monitor whether the Slip phenomenon (Wafer Slip) occurs on the substrate, the flow of the polishing solution, and the like in real time.

Preferably, the carrier head drive assembly 50 according to the present invention is configured with at least two optical sensor units, thereby facilitating the acquisition of the three-dimensional topography of the polishing pad 21 and the distribution of the polishing fluid by means of binocular imaging or structured light projection.

In addition, the lens groups and the image sensors in the

optical sensor units

502 and 503 may also be configured to be rotatable or adjustable in angle, and the angular positions thereof may be adjusted according to the process progress of chemical mechanical polishing, or may be adjusted according to the analysis result of the monitored image data; or as with the

cameras

5033 and 5035 in fig. 4A, so that the lens group and image sensor in the optical sensor unit are mounted towards the edge and bottom of the carrier head 10 so that the optical sensor unit can move down to acquire the thickness and wear of the retaining ring (not shown) of the carrier head 10 when the carrier head 10 is in operation or after it is lifted up.

Further, two or more sets of cameras and image information of different angles may be installed in each of the

optical sensor units

502 and 503, for example, a camera 5033 for obtaining an image toward the edge of the retaining ring of the lower portion of the carrier head 10 may be installed in each of the

optical sensor units

502 and 503, and a camera disposed toward the liquid supply nozzle of the liquid supply device 40 may be installed to monitor the size of the polishing liquid drops and the flow rate of the polishing liquid drops. Fig. 4A shows another variation of the optical sensor unit 503, which may include: a substrate 5030, an inner slide rail 530B fixedly connected to the substrate 5030 and driving the substrate 5030 to move, a camera 5031 and an optical projector 5032 arranged at the bottom of the substrate 5030, and a camera 5033 arranged at the side of the substrate 5030 facing the carrier head 10 to obtain the carrier head 10 and maintain a ring shape, wherein the substrate 5030 is formed into an approximate cube shape and has four substantially vertical side walls or a circumferential side wall; it is easily understood that although not illustrated, a camera and an optical projector may be provided on the sidewall to obtain the thickness and the topographical feature of the polishing liquid crystal layer adhered to the edge of the retainer ring by means of structured light projection measurement, and in addition, a camera 5035 may be provided on the upper surface of the substrate 5030 to make the camera 5035 obtain images of the bottom and lower part of the carrier 10 by lifting the carrier 10 and moving the optical sensor unit 503 below the substrate 5030; in the solution of the present application, the camera head may alternatively be formed as a non-contact and/or contact type temperature sensor for measuring temperature, such as an infrared temperature sensor or the like, to detect the temperature of the polishing pad, the temperature of the polishing liquid, the temperature of the retaining ring, the temperature of different parts of the carrier head, etc.

Fig. 4B shows another variation of the embodiment of the optical sensor unit 503, which is configured with a set of camera 5041 and/or optical projector 5042 capable of changing the viewing angle by a base 504 having a curved wall 5043, the camera 5041 and/or optical projector 5042 can move back and forth along the curved wall 5043 as indicated by the arrow, when moving below the curved wall 5043, the camera 5041 and/or optical projector 5042 is aligned with the upper surface of the polishing pad 21 to measure the information data of the surface such as abrasion, thickness, polishing liquid distribution, temperature, etc., when moving above the curved wall 5043, the camera 5041 and/or optical projector 5042 is aligned with the side of the carrier head 10 to monitor the crystallization of the polishing liquid on the surface of the carrier head 10, the contamination of the retaining ring, the consumption of the retaining ring, etc., and also monitor the wear of the retaining ring, etc.; as another variation of the embodiment of the optical sensor unit 503 shown in fig. 4B, it is easily understood that the arc of 90 degrees in fig. 4B may also be set to an arc of 180 degrees, so that the camera 5041 or the like may align with an object above it by moving to the upper end of the arc, for example, the bottom surface of the carrier head 10 and/or its retaining ring to detect the loading of the substrate and the state of the bottom surface of the retaining ring.

Finally, the

optical sensor units

502, 503, and 504 in the present application are not limited to acquiring optical images, and may be other functional units formed by optical sensors such as infrared distance meters.

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 parts throughout the drawings in order to clearly show the structure of the parts 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 chemical mechanical polishing apparatus comprising: a turntable for rotating the polishing pad therewith; a carrier head configured with a retaining ring to receive a substrate and load the substrate onto the polishing pad; the bearing head driving device comprises a motor, a driving shaft, a pneumatic assembly, a shell and a control unit;

the motor and the pneumatic assembly are arranged in the shell, the driving shaft extends out of the bottom of the shell to transmit the action of the motor and the pneumatic assembly to the bearing head, the outer surface of the shell is provided with an optical sensor unit and a guide rod for actuating the optical sensor unit, the optical sensor unit can move on the surface of the shell along with the guide rod or move below the shell, and the optical sensor unit is provided with at least one angle-adjustable camera or a plurality of cameras which are arranged in different directions to acquire image information of different working areas and parts of the chemical mechanical polishing device;

the optical sensor unit is provided with a first camera, a second camera and a third camera, wherein the first camera is upwards arranged at the top of the optical sensor unit to obtain an image at the bottom of the carrier head, the second camera is horizontally arranged on the side surface of the optical sensor unit to obtain an image on the circumferential surface of the carrier head, and the third camera is downwards arranged at the bottom of the optical sensor unit to obtain an image on the surface of the polishing pad.

2. The chemical mechanical polishing apparatus as recited in claim 1, wherein the camera of the optical sensor unit is rotatable 360 degrees in a horizontal direction and/or 180 degrees in a vertical direction.

3. The chemical mechanical polishing apparatus as recited in claim 2, wherein at least one of the cameras is provided with an optical projector to project illumination light and/or structured light toward the viewing field area.

4. The chemical mechanical polishing apparatus of claim 1, wherein the optical sensor unit is movable to be close to or in contact with a polishing pad to measure a thickness, a wear condition, a contaminant, and a degree of photochemistry of the polishing pad.