TWI691379B - Polishing system, polishing tool and method for modifying substrate thickness profiles - Google Patents

Abstract

A polishing system include a support to hold a substrate having a substrate surface to be polished, a carrier to hold a polishing pad in contact with the substrate surface, and a pressure applicator to apply pressure at a selected region of a back surface of the polishing pad. The back surface is opposite to the polishing surface. The pressure applicator includes an actuator and a body configured to be moved by the actuator into and out of contact with the selected region of the back surface of the polishing pad.

Description

Grinding system, grinding tool and method for modifying substrate thickness profile

The present disclosure relates to chemical mechanical polishing, and more specifically to modifying the substrate thickness profile.

Integrated circuits are usually formed on a substrate by sequentially depositing conductive layers, semiconductive layers, or insulating layers on a silicon wafer. Various manufacturing processes require the planarization of the layers on the substrate. For example, one manufacturing step involves depositing a filler layer on a non-planar surface and planarizing the filler layer. For specific applications, the filler layer is planarized until the top surface of the pattern layer is exposed. For example, a metal layer can be deposited on the patterned insulating layer to fill the trenches and holes in the insulating layer. After planarization, through holes, plugs, and wiring are formed in the remaining metal portions in the trenches and holes of the pattern layer to provide conductive paths between the thin film circuits on the substrate.

Chemical mechanical polishing (CMP) is a recognized method of planarization. This planarization method generally requires the substrate to be mounted on the carrier head. The exposed surface of the substrate is usually placed against a rotating polishing pad. The carrier head provides a controllable load on the backside substrate to push the front side of the substrate against the polishing pad. Slurry with abrasive particles is usually supplied to the surface of the polishing pad.

In commercially available polishing systems, the substrate receives backside pressure, which pushes the exposed surface of the substrate against the rotating polishing pad. However, the substrate has a relatively high stiffness, causing the pressure on the back side of the substrate to be dispersed to a larger area on the front surface of the substrate. For example, the pressure applied to the 1 mm diameter point on the back side of the substrate can be dispersed to cover the area with, for example, 30 mm diameter. As a result, it is difficult to use the backside pressure to accurately control the pressure distribution on the exposed surface of the substrate. Correcting undesired spikes or valleys located in small areas on the exposed surface may become difficult. One technique used to solve this problem is to control the pressure on the polishing pad of the substrate.

In one aspect, the polishing system includes a holder to hold the substrate having the surface of the substrate to be polished, a carrier that holds the polishing pad in contact with the surface of the substrate, and a pressure applicator to apply the selected area on the back of the polishing pad pressure. The backside is opposite to the abrasive surface. The pressure applicator includes an actuator and a body configured to move from the actuator to a selected area that contacts and does not contact the back surface of the polishing pad.

In another aspect, the grinding tool includes a bulk grinding station, a modification station, and a transfer mechanism configured to transfer the substrate between the bulk grinding station and the modification station. The bulk grinding station includes a rotatable platform to support the abrasive article, and a carrier head to keep the substrate having the substrate surface in contact with the abrasive surface of the abrasive article, the carrier head having one or more controllable areas. The modification station includes a support to hold the substrate to be polished, a carrier to keep the polishing pad in contact with the surface of the substrate, and a pressure applicator to apply pressure to a selected area on the back of the polishing pad, which is opposite to the polishing Surface, where The pressure applicator includes an actuator and a body configured to move from the actuator to a selected area that contacts and does not contact the back surface of the polishing pad.

In another aspect, the method of polishing includes the steps of bringing the surface of the substrate into contact with the polishing surface of the polishing pad, the surface of the substrate including one or more underpolished areas, the polishing pad spanning The surface of the substrate applies pressure to one or more selected areas of the back surface of the polishing pad, and hardly applies pressure to the rest of the back surface of the polishing surface, the back surface is opposite to the polishing surface, one or more of the back surface The plurality of selected areas correspond to one or more under-polished areas, and generate relative motion between the substrate and the polishing pad to cause grinding of one or more under-polished areas.

In another aspect, the polishing system includes a support to hold the substrate, the substrate having a surface of the substrate to be polished, an adjustment system for adjusting the polishing pad, the adjustment system including one or more adjustment heads, movable The support structure and the carrier hold the polishing pad. The carrier is suspended from the movable support structure, and the support structure is configured to move the carrier between the supports to hold the base plate and the adjustment system.

Implementation may include one or more of the following advantages. Local pressure can be applied from the front side of the substrate surface being polished without passing through the substrate. The pressure distribution on the surface of the substrate can be finely controlled without dispersing through the substrate, so that local thickness modification can be accurately performed. Local pressure may be applied by pressure control pads having selected sizes and shapes that correspond to the size and/or shape of the area on the substrate that requires thickness modification. Such pressure control pads can move relative to the substrate to modify the substrate thickness at multiple locations. Pressure dispersion can be further reduced by using abrasive pads, The size and/or shape of the polishing pad is based on the size and/or shape of the area on the substrate that requires thickness modification. Alternatively or additionally, one or more elastic rings may be used to apply local pressure to the polishing pad and the substrate to finely modify the thickness of the substrate at the desired location. This thickness modification can be exercised at a modification station that additionally incorporates a polishing pad adjustment system. Multi-cross processing can be exercised where the thickness of one or more substrates is modified while one or more polishing pads are adjusted.

The details of one or more embodiments of the invention are set forth in the drawings and the description below. Other features, objects, and advantages of the present invention will be apparent from the description and drawings, and the claims.

10‧‧‧ substrate

100‧‧‧grinding system

102‧‧‧Modify Station

104‧‧‧Grinding equipment

106‧‧‧Support structure

108‧‧‧Surface

110‧‧‧Abrasive pad

112‧‧‧External abrasive layer

114‧‧‧Backrest

118‧‧‧window

120‧‧‧platform

121‧‧‧Motor

124‧‧‧ drive shaft

125‧‧‧axis

130‧‧‧port

132‧‧‧Slurry

140‧‧‧ bearing head

142‧‧‧Retaining ring

144‧‧‧elastic film

146a‧‧‧chamber

146b‧‧‧chamber

146c‧‧‧chamber

150‧‧‧Rotating rack

152‧‧‧ drive shaft

154‧‧‧ Bearing head rotating motor

155‧‧‧axis

160‧‧‧Monitoring system

162‧‧‧Light source

164‧‧‧Light detector

166‧‧‧ circuit

170‧‧‧ fiber

190‧‧‧remote control

200‧‧‧Modify station

200a‧‧‧Modification station

200b‧‧‧Regulation station

202‧‧‧Grinding head

204‧‧‧Abrasive pad

206‧‧‧Motor

208‧‧‧ direction

210‧‧‧Dock

212‧‧‧ substrate

214‧‧‧upper surface

216‧‧‧Abrasive surface

218‧‧‧Back

220‧‧‧Pressure Applicator

220a‧‧‧pressure control pad

220b‧‧‧pressure control pad

224‧‧‧Load/unload components

240‧‧‧Grinding pad adjustment system

242‧‧‧Adjusting head

260‧‧‧Rotating rack

300‧‧‧fine control grinding head

302‧‧‧Controller

304‧‧‧Surface

305‧‧‧Pressure Applicator

306‧‧‧Surface

308‧‧‧Surface

309‧‧‧Grinding pad adjustment system

310‧‧‧arrow

312‧‧‧ pressure control pad

314‧‧‧ pressure control pad

316‧‧‧arrow

318‧‧‧arrow

402‧‧‧ pressure control pad

404‧‧‧ pressure control pad

406‧‧‧ pressure control pad

408‧‧‧Pressure control pad

500‧‧‧horizontal cross section

502‧‧‧cross section

504‧‧‧Outer periphery

506‧‧‧Inner periphery

508‧‧‧Endpoint

510‧‧‧Endpoint

600‧‧‧Elastic ring

602‧‧‧Upper outer ring

604‧‧‧ Upper radius

606‧‧‧elastic body

608‧‧‧groove

610‧‧‧Central Hub

612‧‧‧ ring

614‧‧‧Moving mechanism

616‧‧‧rib

618‧‧‧ direction

620‧‧‧Top

622‧‧‧Bottom

630‧‧‧Features

702‧‧‧Transfer

704‧‧‧Modify

706‧‧‧Continue

FIG. 1 shows a schematic cross-sectional view of an example of a grinding system.

FIG. 2 shows a block diagram of an example of a modification station.

3 and 4 show schematic top views of part of the modification station.

5A and 5B are schematic cross-sectional views of the pressure control pad.

Fig. 6 is a schematic perspective view of an example of an elastic ring.

6A is a schematic cross-sectional view of an elastic ring.

7 is a flowchart of an example process for modifying the thickness profile of a substrate.

Overview

When the surface of the substrate is polished using a chemical mechanical polishing process, sometimes the substrate material at different locations on the surface is removed at different rates. For example, the substrate material in the surface area near the edge of the substrate may be higher Removal rate, compared to the surface area near the center of the substrate. In another example, the abrasive surface may contain undesired under-milled peaks or over-milled valleys in small local areas, for example, areas with a linear dimension of 10 mm or less. Such peaks or valleys may be caused by defects in the grinding process or grinding equipment.

For simplicity of discussion, the polishing process that basically flattens the surface of the substrate is called bulk polishing, that is, the step height difference caused by the underlying pattern is almost removed, and the removal is intended to remove The bulk part of the material.

The disclosed chemical mechanical polishing process includes one or more additional steps that modify the thickness profile of the substrate before, during, and/or after polishing the bulk of the substrate. In these processes, instead of or in addition to the backside pressure, the surface being ground receives pressure from the front side without passing pressure through the substrate. The front pressure is applied through the polishing pad, and is basically not dispersed by the polishing pad. By finely controlling the area and the amount of pressure applied to the polishing pad, the pressure reached at the surface being polished is finely controlled. The modification of the thickness profile of the substrate can be highly localized and adjustable, and can be performed to different regions, for example, radial regions of the substrate surface. The local pressure may be applied using one or more pressure control pads and/or one or more elastic rings. In some embodiments, back pressure and front pressure may be used in combination.

This thickness modification can be performed mechanically, chemically, or chemically mechanically. In some implementations, one or more additional steps include chemical mechanical grinding steps, which are similar to the chemical mechanical grinding steps used in bulk grinding, except that on the surface being ground The pressure distribution is Finely controlled so that chemical mechanical grinding only occurs in the desired and localized area of the surface.

One or more steps may also include adjusting the polishing pad used in the thickness modification. This adjustment can be conveniently performed at the same station where the thickness modification process is performed. Sometimes the adjustment is only done at selected positions of the polishing pad, which are used to modify the thickness of the substrate at the corresponding positions.

Example grinding system

FIG. 1 illustrates an example of a grinding system 100 including a bulk grinding device 104 and a modification station 102. The substrate 10 to be polished may be transferred between the modification station 102 and the bulk polishing apparatus 104 for thickness modification and bulk polishing. For example, the substrate 10 may be directed to the modification station 102 before, during, or after the substrate 10 is ground in the lapping device 104. The transfer of the substrate 10 can be performed using a mechanism between the station 102 and the device 104, for example, loading/unloading components or a robot arm. In some implementations, the modification station 102 is an independent system. In this case, the modification station 102 may be located near the bulk grinding apparatus 104, for example, in the same processing chamber. Although not shown in the drawings, the station 102 can also be integrated into the device 104.

Body lapping equipment

The grinding device 104 includes one or more carrier heads 140 (only one shown). Each carrier head 140 can be operated to hold the substrate 10 (eg, wafer) against the polishing pad 110. Each carrier head 140 may have independent control of grinding parameters, such as the pressure associated with each respective substrate. Each carrier head 140 includes a fixing ring 142 to hold the substrate 10 on the polishing pad 110 under the elastic film 144.

Each carrier head 140 optionally includes a plurality of independently controllable pressurizable chambers defined by the membrane, for example, three chambers 146a-146c, which can be applied independently The controlled pressure is to the associated area on the elastic membrane 144, and thus to the substrate 10.

Each carrier head 140 is suspended from a support structure 150 (eg, a carousel or rail), and is connected to a carrier head rotation motor 154 by a drive shaft 152 so that the carrier head can rotate around the shaft 155. Alternatively, each carrier head 140 may oscillate laterally, for example, on a slide rail on the rotating rack 150; by the rotational oscillation of the rotating rack itself, or by the dynamics of the carriage, the bracket The rack supports the carrying head 140 along the track.

The platform 120 included in the grinding apparatus 104 is a rotatable disc-shaped platform on which the grinding pad 110 is located. The platform can be operated to rotate about the axis 125. For example, the motor 121 can rotate the drive shaft 124 to rotate the platform 120. The polishing pad 110 may be a double-layer polishing pad having an outer polishing layer 112 and a softer backing layer 114.

The polishing apparatus 102 may include a port 130 to dispense polishing liquid 132 (eg, slurry) to the polishing pad 110 onto the pad. The polishing apparatus may also include a polishing pad adjuster to abrade the polishing pad 110 to maintain the polishing pad 110 in a uniform polishing state.

In operation, the platform rotates about its central axis 125, and each carrier head rotates about its central axis 155, and laterally transfers across the top surface of the polishing pad.

Although only one carrier head 140 is shown, more carrier heads can be provided to hold additional substrates so that the surface area of the polishing pad 110 can have Be effectively used. Therefore, the number of carrier head components adapted to hold the substrate for simultaneous polishing processes may be based at least in part on the surface area of the polishing pad 110.

In some implementations, the grinding equipment includes an in-situ monitoring system 160. The on-site monitoring system may be an optical monitoring system, for example, a spectrum monitoring system, which can be used to measure the spectrum of the reflected light from the substrate being polished. The optical port through the polishing pad is provided by including an aperture (ie, passing through a hole through the pad) or a solid window 118. The on-site monitoring system may alternatively or additionally include an eddy current monitoring system.

In some implementations, the optical monitoring system 160 is an in-sequence optical monitoring system with a probe (not shown) positioned between two grinding equipment, or between the grinding equipment and the transfer station. The monitoring system 160 may continuously or periodically monitor one or more features of the area of the substrate during polishing. For example, one feature is the thickness of each area of the substrate.

In any of the field or sequence embodiments, the optical monitoring system 160 may include a light source 162, a light detector 164, and a circuit 166 for use in the remote control 190 (eg, computer), light source 162, and light detector Send and receive signals between 164. One or more optical fibers 170 may be used to transmit light from the light source 162 to the optical port in the polishing pad, and transmit light reflected from the substrate 10 to the detector 164.

Modify Station

The modification station 102 includes a support structure 106 that provides a surface 108 to receive the substrate 10. The substrate 10 may also be fixed to the support structure 106, for example, by vacuum clamping or clamping.

The fine-control grinding head 300 can be controlled by the controller 302 to selectively modify the thickness at different positions on the surface 308 of the substrate 10. The surface 308 of the substrate 10 may be brought into contact with the polishing surface 304 of the polishing pad 306, and the slurry may be supplied between the two surfaces 304, 306. During polishing, the pressure applied by the discrete areas of the polishing pad 306 is controlled by the pressure applicator 305. Therefore, the fine control of the polishing head 300 may apply pressure on selected positions of the polishing pad 306 to modify the thickness of the substrate 10 in the localized area. For example, the area on the substrate may have a lateral dimension (parallel to the surface) of about 1 mm to 10 mm (eg, 5 mm). This thickness modification can remove material in these regions in nanoscale amounts (eg, 2 nm-100 nm, 10 nm-100 nm, or 50 nm-100 nm).

The controller 302 may store a predetermined thickness profile for the substrate 10, and may control the modification of the substrate thickness based on the stored profile. For example, using the stored profile and the actual thickness profile of the substrate 10 or the expected thickness profile, the fine control grinding head 300 may be instructed to modify the thickness of the substrate to reach the stored profile. The actual thickness profile of the substrate to be modified can be obtained by dry metrology or wet measurement before the modification process starts. In some implementations, the controller 302 stores data, for example in the form of a lookup table, which contains information about the amount and type of thickness modification to be performed for each substrate.

The modification station 102 may also include a monitoring system 304 that provides in-situ measurement or in-line measurement of thickness modification. In some implementations, the monitoring system 304 is similar to the monitoring system 160 of the bulk grinding device 104. For example, the monitoring system 304 may be optical monitoring Depending on the system. The optical fiber of the monitoring system 304 may be projected through an aperture in the polishing pad 306, positioned between two pad sections, or positioned to scan a portion of the substrate that is not in contact with the polishing pad. The optical fiber can project light to the substrate and receive reflection of the light from the substrate.

The monitoring system may communicate with the controller 302 to provide a reflex to the modification process and control the modification process. In the case where the modification is performed before or during the bulk grinding process of the substrate 10, the modification may not necessarily be precise. The thickness modification not only changes the thickness of the substrate 10, but also changes the polishing dynamics of the bulk polishing process performed after the modification. Bulk lapping treatment can achieve uniform in-wafer grinding.

The modification station 102 may additionally include a polishing pad adjustment system 309 for adjusting the polishing pad 306. In some implementations, the modification station 102 includes multiple finely controlled grinding heads 300 for modifying multiple substrates simultaneously on the same support mechanism 106 or different support mechanisms. Sometimes when some substrates are polished, other polishing pads are adjusted.

Modify the substrate thickness profile

Referring to FIG. 2, the example modification station 200 includes a fine control grinding head 202 to which a polishing pad 204 is attached. The pedestal 210 holds the substrate 212 to be polished by the polishing pad 204. The substrate 212 can be loaded from the bulk grinding system using the wafer loading/unloading assembly 224. The substrate 212 may be loaded from other manufacturing tools. The substrate may be loaded before, during, or after the bulk grinding exercise. The base 210 can move the substrate 212 up and down along the vertical direction, as shown by arrow 208. For example, the base 210 may bring the upper surface 214 of the substrate into contact with the polishing surface 216 of the polishing pad 204, To grind the upper surface 214. In addition, during grinding, the base 210 can selectively exert an upward force to apply back pressure to the grinding interface between the surfaces 214, 216. In addition, the base may contain and distribute slurry to the grinding interface between the surfaces 214, 216.

The modification station 200 may include a motor 206 for vertically moving the head 202 and the polishing pad 204 up and down, as shown by arrow 208.

The modification station 200 may also include a motor for generating relative movement between the substrate and the polishing pad during polishing. For example, the modification station may include a motor for rotating or oscillating the head 202 and the polishing pad 204. Alternatively or additionally, the motor may rotate or oscillate the base 210 to provide relative motion. The rotation or oscillation of the polishing pad relative to the substrate 212 polishes the surface 214 of the substrate. During grinding, the downward force exerted by the finely controlled grinding head 202 creates a grinding interface between the front side pressure and the surfaces 214, 216.

The fine control polishing head 202 is configured to hold the polishing pad 204. The polishing pad may be wide enough to span the entire width of the substrate. The back surface 218 of the polishing pad 204 (ie, the side opposite to the polishing surface 216) may be fixed to the fine control polishing head 202 by an adhesive, or held on the head 202 by one or more clamps. In some implementations, only the edge of the polishing pad 204 is fixed to the fine control polishing head 202. In this case, the remaining portion of the back surface 218 (except for the area where the control pad is in contact, discussed below) may be exposed to fluids, such as air, in the internal volume chamber between the polishing pad 204 and the head 202. The internal volume chamber in the head 202 can be ventilated to atmosphere.

The finely controlled polishing head 202 includes one or more pressure applicators 220 for exerting local forces onto the surface 218 of the polishing pad 204. each Each pressure applicator includes an actuator and a body that is controllably mechanically actuated to move into contact and apply pressure to the surface 218 of the polishing pad 204. Therefore, the polishing pad 204 is located between the pressure applicator 220 and the substrate 212. The actuator may be a linear actuator, and may be configured to move the body in a direction perpendicular to the back surface 218 of the polishing pad 204 when attached to the head 202.

The body of the pressure applicator 220 moved to contact the back surface 218 of the polishing pad 204 may be referred to as a "pressure control pad", although the pressure control pad does not need to be a soft or thin body. In the example shown in FIG. 2, the head 202 includes two pressure control pads 220a, 220b, although other numbers of pressure control pads may be used. For example, instead of two pads 221, 220b, there may be a single ring-shaped control pad. In general, the polishing pad 204 is softer than the substrate 212, and the front pressure applied by the pressure control pad passes through the polishing pad without significantly dispersing the pressure. As a result, the pressure received on the substrate surface 214 is almost limited by the size of the contact area between the pressure control pad 220 and the surface 218.

By selecting the size and shape of the contact area or the cross section of the pressure control pad 220, the size and shape of the area to be polished on the substrate surface 214 can be fine-tuned. In some implementations, the size of the contact area or the cross-section of the pressure control pad 220 is selected based on the desired resolution of the smoothness on the surface 214. For example, if the desired smoothness of the surface 214 reaches 10 mm, any local spikes or valleys with dimensions of 10 mm or greater need to be finely ground. The pressure control pad 220 may be selected to have the same size as the local spike size. Therefore, local pressure can be applied to such spikes to smooth the spikes.

Examples of suitable shapes for the cross-section of the pressure control pad 220 Examples are shown in Figures 5A and 5B. Specifically, FIG. 5A shows a horizontal cross section 500 having an arc shape, which corresponds to the contact area between the pressure control pad 220 and the polishing pad surface 218 (see FIG. 2). The arc shape of the cross-section 500 has an outer periphery 504 and an inner periphery 506, which have different curvatures and meet at two end points 508,510. Each perimeter 504, 506 may be part of a cylinder or other structure. At the widest part of the arc, the perimeters 504, 506 are separated by a width w, which is approximately, for example, 1 mm to 10 mm, 1 mm to 5 mm, or 3 mm.

FIG. 5B shows another cross section 502, which also has an arc shape. The pressure control pad 220 having a cross section 502 can be made as a part of a hollow cylinder. The outer diameter R of the cylinder may be selected based on the size of the substrate, for example, about 130 mm to about 150 mm, about 140 mm to about 150 mm, or about 145 mm. The width w of the cylinder may be, for example, about 1 mm to 10 mm, about 1 mm to about 5 mm, or about 3 mm. The arc of FIG. 5B may correspond to the angle α, which is about 10 degrees to about 60 degrees from the center of the cylinder.

For the fine control polishing head 202 of FIG. 2, multiple pressure control pads having different sizes and shapes can be prepared for different defects and different substrates. Prior to use, one or more pressure control pads of suitable shape and size (eg, corresponding to the smallest size of the defect that is intended to be removed) may be selected and installed on the fine grinding control head 202 for use.

The pressure control pads can be moved to a position where local pressure is desirable for local grinding of the substrate. In some implementations, the pressure control pads have a fixed lateral position in the fine control grinding head 202, so the fine control grinding head needs to be moved to position the pressure control pad in the desired area in. In some implementations, the pressure control pads are movable within the finely controlled grinding head 202, for example, by a linear actuator within the head 202. For example, each pressure control pad can move independently of other pressure control pads.

In some implementations, two pressure control pads form a pair and coordinate positioning. For example, the two pressure control pads 220a, 220b may be arranged along the diameter of the substrate 212 or the diameter of the polishing pad 204, and move along the diameter to become relatively closer or further away from each other. In some implementations, as the control pads 220a, 22b move along the diameter, the control pads can be maintained at an equal distance from the center point of the substrate 212 or the polishing pad 204. In some implementations, the rotation of the polishing head 202 is finely controlled, and the pair of pads are equidistant from the axis of rotation.

During the grinding operation, the pressure control pads may remain fixed relative to the fine control grinding head 202, but move with the fine control grinding head 202.

An example of a pair of coordinated pressure control pads 312, 314 is shown in FIG. In this example, each pair of pressure control pads 312, 314 is positioned along the diameter of the substrate 212 on the opposite side of the center C of the substrate. The pressure control pads 312, 314 may be connected to the same movement mechanism, for example, a stepper motor, linear actuator, or pneumatic cylinder, and may move the same relative to the center C along the direction shown by arrow 316的量。 The amount. In some implementations, the pair of pressure control pads can be coordinatedly moved to different positions corresponding to different diameters of the substrate 212, as shown by arrows 318, 310. At different diameters, the pressure control pads 312, 314 can again move along different diameters.

During polishing, as previously described, the polishing head 202 and the polishing pad 204 can be controlled to rotate relative to the substrate 204. As a result, pressure control The pad 220 also rotates relative to the substrate 204. Local grinding by local pressure applied from the polishing pad 220 may occur along the entire radial circle. In some implementations, instead of rotating the polishing head 202 and the polishing pad 204, the motor 206 vibrates the polishing pad to remove material from the substrate surface 214 at a position corresponding to the pressure control pad 220. At a later time, the pressure control pad 220 may be moved to a different location to remove material from the different location. The positions of the pressure control pads can be predetermined based on the desired thickness profile and the actual thickness profile of the substrate.

In some implementations, the finely controlled grinding head 202 of FIG. 2 may include multiple pairs of pressure control pads that are arranged along different diameters and separated by different distances. For example, FIG. 4 shows two pairs of pressure control pads: 402, 404 are arranged along one diameter of the substrate 212, and 406, 408 are arranged along different diameters of the substrate 212. Each pair of pressure control pads may have features similar to the pressure control pads 302, 304 of FIG. The pads 406, 408 are closer to each other than the pads 402, 404. When the polishing pad 204 rotates relative to the substrate 212, the two pairs of pressure control pads polish two circular regions, which have different radii relative to the center C. When the polishing pad 204 vibrates, the two pairs of pressure control pads simultaneously and effectively polish four different positions of the substrate surface 214.

In some implementations, the finely controlled grinding head 202 of FIG. 2 includes multiple independent pressure control pads. Each independent pressure control pad can be independently controlled for its position relative to the substrate 212 (eg, the center C of the substrate 212), the pressure applied to the polishing pad surface 218, and the length of time the pressure is applied.

In some cases, rather than being fixed relative to the polishing pad 204, the pressure control pad or pair of pressure control pads can move relative to the polishing pad during polishing, for example, scanning along a path.

In some implementations, different pressure amounts and/or different polishing time lengths can be controlled by independent pressure control pads or independent pressure control pads at different positions of the substrate according to the local grinding amount required to achieve the desired thickness and smoothness profile Applied to. For example, sometimes the bulk grinding of the substrate causes the substrate to have a so-called asymmetry problem, where the thickness variation is greater near the edge of the bulk grinding substrate than in the central area of the substrate. The thickness modification in the center area and the edge area of the substrate can be performed differently to achieve a uniform thickness within the substrate surface 214.

In some implementations, unlike those shown in FIGS. 3 and 4, the size of the polishing pad 212 is selected to be similar to the size of the area requiring local polishing, and is smaller than the size of the substrate 212. For example, the polishing pad 212 may have a diameter of about 120 mm to about 150 mm. A fine polishing control head similar to the head 202 may have multiple polishing pads, which have different sizes. In use, a suitable polishing pad can be selected and moved from one location to another location on the substrate surface 214 to locally remove material at those locations. The small size of the polishing pad 212 can further reduce the possible dispersion of the front pressure applied by the pressure control pad. The grinding can be applied in selected areas without affecting other areas.

Referring to FIGS. 6 and 6A, instead of or in addition to the pressure control pad 220 described above, the pressure applicator may include an elastic ring 600 for applying local front pressure to the polishing pad surface 218. The elastic ring 600 includes an upper outer ring 602 having a fixed upper radius 604 and an elastic body 606 connected to the upper outer ring 602. The elastic body 606 and the upper outer ring 602 may be integrally formed. The elastic body includes a groove 608 extending from the upper outer ring 602 to the elastic body 606 so that the elastic body 606 is connected to the upper outer ring The top 620 of the elastic body at 602 has a fixed radius that is the same as the radius 604, and the bottom 622 of the elastic body 606 can shrink or expand by increasing or decreasing the size of the groove 608 at the bottom 622.

The elastic ring 600 also includes a central hub 610 that includes a movement mechanism 614 and a ring 612, which is connected to the movement mechanism. The central pivot 610 is connected to the bottom 622 of the elastic body 606 by ribs 616 that extend from the ring 612. The movement mechanism 614, which may be a motor, a linear actuator, or a cylinder, may move up and down along a direction 618, which is perpendicular to the upper outer ring and parallel to the long axis of the body 606. The rib 616 may be elastic so that as the central hub 610 moves upward toward the upper outer ring 602, the rib 616 pulls the body 606 inward so that the diameter of the bottom 622 decreases, for example, in position A. As the central hub 610 moves downward away from the upper outer ring 602, the ribs push the body 606 outward so that the diameter of the bottom 622 increases, for example, at position B.

As a result, the elastic ring 600 may replace the pressure control pad 220 of FIG. 2, and the bottom 622 of the elastic ring 600 may contact the polishing pad surface 218 to generate local pressure at the desired radial position of the substrate 212. At least in the radial position, the local pressure can be evenly distributed along the corresponding circle. The radial extent of the bottom 622 can be selected based on the needs of the substrate 212. For example, the radial range may be about 140 mm to about 150 mm. To produce the desired radial range, one or more factors, including the size and material of the rib 616, the size and material of the upper outer ring 602 and the body 606, the range of motor movement, and/or the size of the groove, can be Consider. As an example, suitable materials for the upper outer ring 602, the main body 606, and the ribs 616 include plastics with good flex fatigue 胶材料。 Glue material. Examples of materials used for the ribs include nylon, polyphenylene sulfide (PPS), polyether ether ketone (PEEK), and polyethylene terephthalate (PET). The bottom 622 may have a width similar to that of the pressure control pad 220, for example, about 1 mm to about 10 mm, about 1 mm to 5 mm, or about 3 mm.

In some embodiments, the bottom 622 of the body 606 additionally includes discrete features 630 for direct contact with the polishing pad surface 218. The feature 630 may have a desired shape and size, for example, similar to the shape and size of the pressure control pad 220. In some implementations, different features at different locations of the bottom 622 may have the same or different shapes and/or sizes. These features may be permanently attached to the body 606, or integrally formed with the body, or may be detachable so that the user can select where pressure is applied to the substrate 212.

In some implementations, the modification station 200 of FIG. 2 may include more than one elastic ring 600. Each elastic ring may be configured to apply local pressure to a selected radial range, and different elastic rings may correspond to different radial ranges. The modification station 200 may also include a combination of the elastic ring 600 and the pressure control pad 220.

Referring to FIG. 7, an example process 700 is shown for modifying the thickness profile of a substrate to be, is being, or has been ground by a chemical mechanical body block. The substrate is transferred (702) to the modification station when it is determined that the thickness profile of the substrate needs to be modified at the beginning, before, during, or after the substrate is ground by the bulk. During or after the substrate is ground, the substrate can be transferred from the grinding head of the bulk grinding apparatus. Before the substrate is ground, the substrate may be transferred from another processing station, which has processed the substrate to be ground. The thickness profile of the substrate is then modified by chemical machinery (704). Specifically, the modification can be performed on one or more localized regions on the substrate surface. Modify the profile, for example, will be The amount of material removed, the location of removal, etc., can be viewed in the data stored for different types of substrates and grinding systems, or can be determined on site. This modification can be monitored on-site or off-line to determine whether the desired thickness profile has been reached. Sometimes, for example, when the modified substrate is to be ground or further ground, the modification does not need to be accurate, for example, up to nanometers, but only needs to be accurate to 10 nanometers or more. Finally, the substrate is transferred to continue (706) the chemical mechanical polishing process. In the case where the modification is performed after the substrate is completely polished, the entire process ends.

Grinding pad adjustment system

Referring again to FIG. 2, the modification station 200 may additionally include a polishing pad adjustment system 240 that can abrad the polishing pad surface 216 to maintain the polishing pad 204 in a consistent polishing state and move from the pad surface 216 Debris. The adjustment system 240 includes a pad adjustment head 242 for resurfacing the pad surface 216, and a cleaning assembly 244 for delivering water and/or chemicals to the polishing pad surface 216 to facilitate adjustment. For example, water and/or chemicals can clean the pad surface 216 and remove debris from the pad surface 216. The adjustment system 240 may be independent of the modification station 200, and the polishing pad 204 may be moved to the system 240 and adjusted between substrate modification processes.

In the example shown in FIG. 2, the adjustment system 240 is integrated in the modification station 200. The adjustment head 242 and the cleaning assembly 244 may be stored in the open cavity of the base 210 before and during the modification process is applied to the substrate 212. After the substrate 212 completes its thickness modification, the adjustment head 242 and the cleaning assembly 244 can be raised to be exposed to and/or contact the polishing pad surface 216. Alternatively, the adjustment head 242 may be at a larger outer diameter than the polishing pad 204 and the substrate 212, laterally The ground is placed in a direction perpendicular to the direction 208. During the modification process, the adjustment head 242 does not contact the substrate 212 or the polishing pad 204. After the modification process is completed, the adjustment head 242 may be moved laterally below the grinding surface 216 to adjust the grinding surface 216.

Sometimes because the polishing pad surface 216 is only used to modify the selected position in the process, the adjustment head 242 can be adjusted laterally to those selected positions of the polishing pad surface 216. The adjustment is then exercised at these selected positions instead of the entire pad surface 216. As previously described, the polishing pad surface 216 may have a small size to cover the local area of the substrate that requires thickness modification. In such a case, the entire polishing pad surface 216 can be adjusted. A description of the adjustment head used in the adjustment system, such as the adjustment head 242 of the system 240, can be found in US Patent No. 6,036,583, the entire contents of which are incorporated herein by reference.

In some implementations, the system includes multiple stations. In the example shown in FIG. 2, the system 200 includes a modification station 200a and an adjustment station 200b. The modification station 200a includes a substrate support 210. The regulating station 200b includes a regulating system 240. The abrasive carrier 202 may be suspended from a movable support (eg, a rotatable rotating rack) that is configured to transfer the carrier 202 between the modification station 200a and the adjustment station 200b. The stations of the system can be spaced at equal angular intervals around the axis of rotation of the rotating rack.

In some implementations, the modification station 200 includes multiple modification stations that have the same characteristics as the modification station described above in relation to FIG. 2.

The rotating stock 260 can coordinate the processing performed by the stations 200a, 200b to produce a polishing pad with a high output. For example, when the sub-modification station 200a is modifying the thickness profile of the substrate 212, the sub-modification station 200b adjusts the polishing pad 204.

As used in the current specification, the term substrate may include, for example, a product substrate (for example, a product substrate including multiple memories or processor chips), a test substrate, a bare substrate, and a gate substrate (gating substrate). The substrate may be at various stages of integrated circuit manufacturing, for example, the substrate may be a bare wafer, or the substrate may include one or more deposited and/or patterned layers. The terminology of the substrate may include discs and rectangular thin plates.

The above-mentioned grinding equipment and method can be applied to various grinding systems. Either the polishing pad, or the carrier head, or both can be moved to provide relative movement between the polishing surface and the substrate. For example, the platform can orbit rather than rotate. The polishing pad may be a circular (or some other shape) pad fixed to the platform. Some aspects of the endpoint detection system can be applied to a linear polishing system, for example, where the polishing pad is a linearly moving continuous belt or a reel-to-reel belt. The abrasive layer can be a standard (for example, polyurethane with or without filler) abrasive material, a soft material, or a fixed abrasive material. The term relative positioning is used; it should be understood that the abrasive surface and substrate can be held in a vertical orientation or some other orientation.

Although the above description mainly focuses on the control of the chemical mechanical polishing system, the modification station can be applied to other types of substrate processing systems, for example, etching or deposition systems.

The control of various systems and processes (or parts of systems and processes) described in this manual can be implemented in computer program products, which include instructions that are stored on one or more non-transitory machines The storage medium can be read, and the instructions can be executed on one or more processing devices. The system described in this specification, or part of the system, can be implemented as a device, A method or electronic system that can include one or more processing devices and memory to store executable instructions to perform the operations described in this specification.

Although this description contains many specific implementation details, these details should not be constructed as limitations on the scope of any invention, or on claims, but as features specific to specific embodiments of particular inventions Description. The specific features described in the context of separate embodiments in this specification can also be implemented in combination in a single embodiment. Conversely, various features described in the context of a single embodiment can also be implemented separately in multiple embodiments or in any suitable sub-combination. In addition, although the features may be described above as acting in a particular combination, and even originally claimed to be so, one or more features from the claimed combination may be executed from the combination in some cases, and the claimed combination May be directed to sub-combinations or variations of sub-combinations.

Similarly, although the operations are depicted in the drawing in a specific order, this should not be understood as requiring such operations to be performed in the specific order shown, or sequentially, or all illustrated operations to be performed to achieve the desired result. In certain situations, multitasking and parallel processing may be advantageous. In addition, the separation of various system modules and components in the above embodiments should not be understood as requiring such separation in all embodiments, and it should be understood that the described program components and systems can usually be integrated together in a single In software products or packaged into multiple software products.

Specific embodiments of the subject matter have been described. Other embodiments are within the scope of the following request items. For example, the actions recorded in the request item can be performed in a different order and still achieve the desired result. As an example, the processing depicted in the drawings does not necessarily require the particular order shown or sequential order to reach the deadline Hope the result. In some cases, multiplexing and parallel processing may be advantageous.

200: modify station

200a: modify station

200b: regulating station

202: Grinding head

204: polishing pad

206: Motor

208: direction

210: pedestal

212: substrate

214: upper surface

216: Abrasive surface

218: back

220: pressure applicator

220a: pressure control pad

220b: pressure control pad

224: Load/unload components

240: Grinding pad adjustment system

242: Adjusting the head

260: Rotating feeder

Claims (35)

A polishing system comprising: a stand to hold a substrate having a surface of a substrate to be polished; a carrier to keep a polishing surface of a polishing pad in contact with the surface of the substrate; And a pressure applicator to apply pressure at a selected area of a back surface of the polishing pad, the back surface being opposite to the polishing surface, wherein the pressure applicator includes an actuator and a body configured to The actuator moves to contact and not contact the selected area of the back surface of the polishing pad. The polishing system according to claim 1, wherein the carrier is configured to hold the polishing pad, the polishing pad having a larger width than the substrate so that the polishing pad contacts the entire substrate. The polishing system of claim 2, wherein the carrier is configured to be fixed to the polishing pad only at the edge of the polishing pad. The polishing system of claim 3, wherein the carrier is configured such that a remaining portion of the back surface of the polishing pad within the edge is open to a fluid in a chamber. The polishing system of claim 1, wherein the pressure applicator includes one or more pressure control pads, each of the pressure control pads has a cross-sectional area to contact the back surface of the polishing pad. The grinding system of claim 5, wherein each cross-sectional area has a lateral dimension of about 1 mm to about 10 mm. The grinding system according to claim 6, wherein each cross-sectional area has a shape of an arc. The polishing system of claim 5, wherein the pressure applicator includes a plurality of pressure control pads that can move laterally relative to the polishing pad. The polishing system of claim 8, wherein each pressure control pad can move laterally independently of the other pressure control pads. According to the polishing system of claim 8, when the substrate is held by the substrate support, each pressure control pad can move laterally relative to a position of a center of the substrate surface. The polishing system according to claim 10, wherein the plurality of pressure control pads includes a pair of pressure control pads, and the pair of pressure control pads can coordinately move relative to the center of the substrate surface. The polishing system according to claim 1, includes a driving system to generate relative movement between the substrate and the polishing pad. The polishing system according to claim 1, wherein the pressure applicator includes an elastic ring having a top structure and a bottom structure, the top structure has a fixed diameter, and the bottom structure has a cross-section, It is used to contact the back surface of the polishing pad and has an adjustable diameter. The polishing system according to claim 13, wherein the elastic ring further includes a rib and a moving mechanism, each rib has an end connected to the moving mechanism between adjacent grooves of the body, and the other end The point is connected to a bottom of the body, wherein the movement mechanism is configured to move along a long axis of the body to adjust the diameter of the body at the bottom. The polishing system of claim 1, further comprising an adjustment system for adjusting the polishing surface of the polishing pad, the adjustment system including one or more adjustment heads, the adjustment heads configured to move to, And adjust, one or more areas of the abrasive surface, these areas correspond to the one or more selected areas of the back surface. A grinding tool includes: a bulk grinding station, the bulk grinding station includes: a rotatable platform to support an abrasive product, and A carrier head to keep a substrate in contact with one of the abrasive surfaces of the abrasive article, the substrate has a surface of the substrate, the carrier head has one or more controllable areas; a modification station, the modification station includes : A stand to hold the substrate to be polished; a carrier to keep a polishing pad in contact with the surface of the substrate; and a pressure applicator to apply at a selected area of a back surface of the polishing pad Pressure, the back surface is opposite to the abrasive surface, wherein the pressure applicator includes an actuator and a body configured to be moved by the actuator to contact and not contact the selected area of the back surface of the polishing pad And a transfer mechanism configured to transfer the substrate between the bulk grinding station and the modification station. A method of grinding, the method comprising the steps of: bringing a surface of a substrate into contact with a grinding surface of a grinding pad, the surface of the substrate comprising one or more underpolished areas, the grinding The pad spans the surface of the substrate; applying pressure to one or more selected areas of a back surface of the polishing pad without applying pressure to the remaining part of the back surface of the polishing surface, the back surface being opposite to the polishing The surface, the one or more selected areas of the back face correspond to the one or more under-polished areas; and a relative motion is generated between the substrate and the polishing pad to cause the one or more under-polished areas Grinding of areas. The method of claim 17, wherein the step of applying pressure includes moving a body with an actuator to contact the selected area of the back surface of the polishing pad. The method according to claim 17, wherein the step of applying pressure includes: contacting the back surface of the polishing pad with a surface of the pressure control pad, the surface having a size and a shape corresponding to the size of the substrate The one or more under-ground areas of the surface. The method according to claim 17, the method comprising the steps of: laterally moving the pressure control pad relative to a position of a center of the surface of the substrate. A polishing system includes: a stand to hold a substrate having a substrate surface to be polished; an adjustment system for adjusting a polishing pad, the adjustment system including one or more adjustment heads A movable support structure; and a carrier to hold a polishing pad, the carrier is suspended from the movable support structure, wherein the movable support structure is configured to move the carrier and the polishing pad between the support To hold the substrate and the adjustment system. The grinding system according to claim 21, wherein the movable support structure includes a rotatable rotating rack. The grinding system according to claim 21, comprising a plurality of stations, which are spaced at equal angular intervals around a rotation axis of the rotating material rack, at least one of the stations including the support to hold the Base plate, and at least one of the different stations includes the adjustment system. The polishing system of claim 21, wherein the carrier is configured to hold the polishing pad, wherein a polishing surface of the polishing surface faces downward relative to gravity. The grinding system according to claim 21, comprising a robot arm configured to insert the substrate horizontally onto the support. The polishing system of claim 21 includes a cleaning assembly configured to deliver a cleaning fluid to the polishing surface of the polishing pad when the polishing pad is positioned above the adjustment system. The grinding system of claim 21, wherein the one or more adjustment heads are configured to contact the grinding surface at one or more positions corresponding to the back side where pressure is applied One or more selected areas. The polishing system of claim 21, wherein the carrier is configured to hold the polishing pad, the polishing pad having a larger width than the substrate so that the polishing pad contacts the entire substrate. The polishing system of claim 28, wherein the carrier is configured to be fixed to the polishing pad only at the edge of the polishing pad. The polishing system of claim 21, wherein the carrier is configured to hold the polishing pad, the polishing pad having a width smaller than the substrate, such that the polishing pad contacts less than all of the substrate. The polishing system of claim 21, wherein the plurality of adjustment heads are positioned radially outwardly around the support. A polishing system includes: a stand to hold a substrate with a substrate surface to be polished; a carrier to hold a polishing pad, the carrier is suspended from a movable support structure, wherein the The mobile support structure is configured to move the carrier and the polishing pad between the support to hold the substrate and the adjustment system; and an adjustment system for adjusting the polishing pad, the adjustment system includes an adjustment head The adjustment head is stored in a chamber in the support, and is configured to lift out the support to contact the polishing pad when the substrate is not held on the support. The polishing system of claim 32 includes a pad cleaning system to supply a cleaning fluid to the polishing pad. The polishing system of claim 33, wherein the pad cleaning system is stored in a chamber in the support and is configured to lift the support out when the substrate is not held on the support The cleaning fluid is directed onto the polishing pad. A polishing system includes: a stand to hold a substrate with a substrate surface to be polished; a carrier to hold a polishing pad, the carrier is suspended from a movable support structure, wherein the The mobile support structure is configured to move the carrier and the polishing pad between the support to hold the substrate and an adjustment system; and a pad cleaning system to supply a cleaning fluid to the polishing pad, the pad cleaning system An adjustment head is included, which is stored in a cavity in the support and is configured to lift the support to contact the polishing pad when the substrate is not held on the support.

Images