Searching substrate recesses on substrate between platforms in chemical mechanical polishing

Abstract

The recess detection station includes a sensor for generating a signal dependent on a proportion of a sensing area of the sensor covered by the substrate and a controller. The controller is configured to cause the actuator to position the carrier head relative to the sensor such that the sensing area of the sensor is located at the edge of the substrate, cause the motor to generate rotational motion such that the sensing area of the sensor scans along the circumference of the substrate, and detect an angular position of a recess in the edge of the substrate based on a signal from the sensor, the method includes compensating for a sinusoidal component of a signal generated due to the substrate center deviating from the rotation axis.

Description

Technical Field

[0001] This disclosure relates to probing the angular position of a substrate, such as the position of a substrate recess, in a chemical mechanical polishing (CMP) system. Background Technology

[0002] Integrated circuits are typically formed on a substrate by sequentially depositing conductive, semiconductor, or insulating layers on a silicon wafer. One manufacturing step involves depositing a filler layer on a non-planar surface and planarizing the filler layer. For some applications, the filler is planarized until the top surface of the patterned layer is exposed. For example, a conductive filler layer may be deposited on a patterned insulating layer to fill trenches or holes in the insulating layer. After planarization, portions of the metal layer remaining between the raised patterns of the insulating layer form vias, plugs, and fine lines, providing conductive paths between thin-film circuits on the substrate. For other applications, such as oxidation polishing, the filler layer is planarized until a predetermined thickness is left on the non-planar surface. Furthermore, photolithography often requires planarization of the substrate surface.

[0003] Chemical mechanical polishing (CMP) is a widely accepted planarization method. This planarization method typically requires mounting the substrate on a carrier or polishing head. The exposed surface of the substrate is usually placed on a rotating polishing pad. The carrier head applies a controlled load to the substrate, pushing it toward the polishing pad. The surface of the polishing pad typically contains an abrasive polishing slurry. Summary of the Invention

[0004] A polishing apparatus includes: multiple stations, including a first station and a second station, the first station being a polishing station or a transfer station, and the second station being a polishing station; a carrier head for holding a substrate, the carrier head being movable along a path from the first station to the second station by an actuator; a motor for rotating the carrier head about a rotation axis; a groove detection station positioned on a path between the first station and the second station, the groove detection station including a sensor for generating a signal based on the proportion of the sensor's sensing area covered by the substrate; and a controller. The controller is configured to position the carrier head with the actuator to position the substrate at the groove detection station, to position the sensor's sensing area at the edge of the substrate, to rotate the carrier head with the motor to scan the sensor's sensing area along the circumference of the substrate, and to detect the angular position of a groove in the edge of the substrate based on the signal emitted by the sensor, including compensating for the sinusoidal component of the signal generated due to the substrate's center deviating from the rotation axis.

[0005] In another aspect, a method includes the steps of: holding a substrate in a carrier head, the substrate being positioned such that the sensing area of ​​a sensor of a groove detection station is located at the edge of the substrate; rotating the carrier head to rotate the substrate, causing the sensing area of ​​the sensor to scan along the circumference of the substrate; and detecting the angular position of a groove in the edge of the substrate based on a signal from the sensor, including compensating for the sinusoidal component of the signal caused by the center of the substrate deviating from the axis of rotation.

[0006] In another aspect, a groove detection station includes: a sensor for generating a signal that depends on the proportion of the sensing area of ​​the sensor covered by a substrate; and a controller configured to cause an actuator to position a carrier head relative to the substrate, with the sensing area of ​​the sensor located at the edge of the substrate, to cause a motor to generate relative motion between the carrier head and the sensor, thereby causing the sensing area of ​​the sensor to scan along the circumference of the substrate, and to detect the angular position of a groove in the edge of the substrate based on the signal emitted by the sensor, including compensating for the sinusoidal component of the signal caused by the center of the substrate deviating from the axis of rotation.

[0007] Specific embodiments may include one or more of the following potential advantages: The angular position of the substrate relative to the carrier head can be determined, and the carrier head can be rotated to position the substrate recess at the desired angular position. Polishing can be performed more consistently between each wafer, thereby reducing inter-wafer uniformity (WTWNU). In-situ monitoring can be more reliable, thereby improving both intra-wafer uniformity (WIWU) and inter-wafer uniformity (WTWU).

[0008] Details of one or more specific embodiments are set forth in the accompanying drawings and the description below. Other aspects, features, and advantages will become apparent from the description, the drawings, and the claims. Attached Figure Description

[0009] Figure 1 This is a plan view of an example polishing apparatus.

[0010] Figure 2 This is a cross-sectional schematic diagram of an example polishing apparatus.

[0011] Figure 3 This is a schematic side view of an example of an inter-platform groove detector.

[0012] Figure 4A and 4B This is a schematic top view of a substrate with different grooves.

[0013] Figure 5 This is a bottom view of the substrate and the retaining ring, showing the path of the scanning point along the circumference of the substrate.

[0014] Figure 6 This is a schematic diagram showing the functional relationship between the intensity of reflected light and the position of the bearing head.

[0015] Figure 7 This is a schematic side view of another example of an inter-platform recessed detector that includes two light sources.

[0016] Figure 8 This is a schematic side view of another example of an inter-platform recessed detector that includes a camera.

[0017] Figure 9 This is a schematic side view of another example of an inter-platform groove detector, guiding a beam of light through a column of water.

[0018] Figure 10 This is a schematic side view of another example of an inter-platform recess detector in which one side of a substrate is immersed in a liquid tank.

[0019] The symbols for similar components in the various attached figures represent components of the same type. Detailed Implementation

[0020] In some polishing operations, the substrate is held in place by a rotating support head and pressed against a rotating polishing pad. The rotation of the support head also applies rotation to the substrate.

[0021] Before performing chemical mechanical polishing, it is best to align each substrate with a consistent angular orientation. This improves the reproducibility of polishing and in-situ film thickness measurement, especially for patterned wafers. Without being limited to any particular theory, consistent angular orientation increases the likelihood that the sensor scans each substrate along a repeatable path, ensuring that the generated signal, as a function of time, is always located on the same portion of the substrate, on an inter-wafer basis. This correspondingly improves the reliability of the pressure control algorithm, thereby enhancing intra-wafer uniformity (WIWU) and inter-wafer uniformity.

[0022] Suppose that before polishing begins, such as before the substrate descends and contacts the polishing pad, the carrier head can simply rotate to a preset angular orientation. However, the angular orientation of the substrate relative to the carrier head may not remain fixed; the substrate may be subject to a "precession" effect, meaning that the substrate may rotate relative to the carrier head. Therefore, relying solely on the orientation of the carrier head, such as the orientation measured by a motor encoder, may be insufficient.

[0023] The technique to solve this problem involves measuring the angular orientation of the substrate before the polishing operation or between two separate polishing operations, such as at a station located between two platforms of the polishing system. For example, a beam of light can be directed at the edge of the substrate, a detector can measure the intensity of the reflected light, and a rotating support head can be used. As the groove passes the irradiation point, the amount of reflected light should change, for example, decrease.

[0024] Another issue is that when the substrate is "attached" to the carrier head for transport between platforms, the center of the substrate may not be precisely aligned with the axis of rotation of the carrier head. Therefore, simply rotating the carrier head to scan the sensors around the substrate's circumference may not be feasible. For example, the sensors might move outside the substrate's radius, resulting in signal loss. Furthermore, the signal emitted by the sensors changes simply because the scan crosses different radial positions on the substrate; this change may exceed the effect of the grooves on the signal, thus obscuring the location of the grooves.

[0025] The technique to solve this problem is to detect and filter out sinusoidal changes in the signal from the sensor, and then detect changes in the signal, such as a decrease in signal strength, which indicates the presence of a groove.

[0026] Figure 1 This is a plan view of a chemical mechanical polishing apparatus 100 for processing one or more substrates. The polishing apparatus 100 includes a plurality of polishing stations 110. For example, the polishing apparatus may include three polishing stations 110a, 110b, and 110c. The polishing apparatus 100 also includes at least one carrier head 140, for example, four carrier heads 140. The polishing apparatus 100 also includes a transfer station 104 for loading and unloading substrates from the carrier heads 140. The stations of the polishing apparatus 100, including the transfer station 104 and the polishing stations 110, may be positioned at substantially equal angular intervals around the center of a platform 106.

[0027] Reference Figure 2 Each polishing station 110 includes a polishing pad 130 supported on a rotatable platform 120. The polishing pad 130 may be a double-layer polishing pad, having an outer polishing layer 132 and a softer backing layer 134 (see...). Figure 2 The top surface of polished layer 132 can provide polished surface 136.

[0028] Back Figure 1 For the polishing operation, a carrier head 140 is positioned at each polishing station 110. Another additional carrier head 140 may be positioned in a transfer station 122 to exchange polished substrates for unpolished substrates while other substrates are being polished at polishing station 110.

[0029] The carrier head 140 is held in place by a support structure (e.g., a rotatable rack or a trolley suspended on a track) that allows the carrier head to move along a path 106 that passes sequentially through each polishing station 110a-110c and a transfer station 104.

[0030] Reference Figure 1 and Figure 2Each polishing station 110 may include a port 160 (e.g., at the end of arm 162) for dispensing polishing fluid 164 (e.g., abrasive slurry) onto polishing pad 130. Each polishing station 110 of the polishing apparatus 100 may also include a polishing pad adjustment device 170 for abrading the polishing pad 130 to maintain the polished surface 136 in a consistent abrasion state. For example, the adjustment device may include an adjustment head 172 with an adjustment disc at the end of arm 174.

[0031] like Figure 2 As shown, each platform 120 is rotatable about axis 122. For example, motor 124 can rotate drive shaft 126 to rotate platform 120.

[0032] Each carrier head 140 can be used to hold the substrate 10 on the polishing pad 130. Each carrier head 140 may include a retaining ring 142 for securing the substrate 10 below the flexible diaphragm 144. Each carrier head 140 may also include a plurality of independently controllable pressurized chambers defined by the diaphragm, such as three chambers 146a-146c, which can apply independently controllable pressure to a relevant area on the flexible diaphragm 144, thereby applying pressure to the substrate 10. Although for the sake of illustration, Figure 2 The diagram only shows three chambers, but there could be one or two chambers, or four or more chambers, such as five chambers.

[0033] Each support head 140 is suspended on a support structure 150 and connected to a support head rotary motor 156 via a drive shaft 154, so that the support head can rotate about axis 152. Depending on the situation, each support head 126 can oscillate laterally, for example, driven by a trolley on a track, driven by a motor that causes the support head to oscillate radially, or driven by the rotational oscillation of the rack itself.

[0034] During operation, the platform rotates about its central axis 121, each bearing head rotates about its central axis 127, and translates laterally across the top surface of the polishing pad.

[0035] The in-situ monitoring system may include sensors 180 mounted in the platform 120 for monitoring the progress of the polishing operation and / or measuring the layer thickness on the substrate 10 being polished. Sensors 180 may be optical sensors, such as spectrometers, eddy current sensors, capacitive sensors, tribological sensors, etc.

[0036] A controller 190 (such as a programmable computer) is connected to each motor 126, 156 to independently control the rotational rate of the platform 120 and the carrier head 140. For example, each motor 156 may include an encoder 158 for measuring the angular position or rotational rate of the associated drive shaft 154. The associated drive shaft may have its own reference angular position, which the encoder 158 can identify to measure the number of rotations of the drive shaft.

[0037] The controller 190 is also connected to a pressure regulator to control the pressure in chambers 146a-146c. Specifically, the controller 190 can be configured to receive thickness measurements from an in-situ monitoring system and control the pressure in chambers 146a-146c to provide improved polishing uniformity.

[0038] The controller 190 may include a central processing unit (CPU) 192, memory 194, and support circuitry 196, such as input / output circuitry, power supply, frequency circuitry, cache, etc. The memory is connected to the CPU 192. The memory is a non-transitory computer-readable medium and may be one or more readily available types of memory, such as random access memory (RAM), read-only memory (ROM), floppy disk, hard disk, or other forms of digital storage. Furthermore, although illustrated as a single computer, the controller 190 may be a distributed system, for example, including multiple independently operating processors and memories.

[0039] Reference Figure 1 and Figure 3 The polishing apparatus 100 may also include one or more groove detection stations 200. In some specific embodiments, a groove detection station 200a is positioned on path 106 between conveyor station 104 and the first polishing station (e.g., polishing station 110a). One or more groove detection stations 200b, 200c may be positioned on path 106 between two polishing stations 200, traversed by the carrier head 140.

[0040] In some specific embodiments, the polishing system includes two inter-platform groove detection stations 200b and 200c. The two inter-platform groove detection stations 200b and 200c may be located on paths 106 on opposite sides of a polishing station (e.g., a second polishing station 110b).

[0041] In some operating modes, the substrate orientation is measured at a recess detection station 200 located before polishing station 110 along path 106, and then the substrate moves forward along path 106 to polishing station 110, where it is polished. However, in some operating modes, the substrate orientation can be measured at a recess detection station 200 located after polishing station 110 along path 106, and then the substrate moves backward along path 106 to polishing station 110, where it is polished. The substrate can then move forward along path 106 again to the next polishing station, optionally stopping at recess detection station 200 before polishing at the next polishing station.

[0042] Figure 3 A specific embodiment of a groove detection station 200 located between two platforms 120 of two adjacent polishing stations 110 along a path is shown. This embodiment of the groove detection station 200 has an optical groove detector 210, which includes a light source 212, a photodetector 214, and a circuit system 216 for transmitting and receiving signals between the controller 190 and the light source 212 and the photodetector 214. The optical groove detector 210 can also be considered as including some functions implemented in the controller 190, such as software.

[0043] The position of the light source 212 allows the substrate carrier head 140 to be positioned on path 106, where the substrate 100 can be scanned by the optical recess detector 210. Specifically, the light source 212 generates a light beam 220 that can be reflected by the substrate 10, and the photodetector 214 is positioned to receive the reflected light beam 222 from the substrate 10. The photodetector 214 can be positioned where the incident angles of the light beam 220 and the reflected light beam 222 are equal, for example, so that the photodetector 214 receives the reflected light (rather than the scattered light). The incident angle on the substrate 10 can be the normal to the substrate surface or an angle not exceeding 80°, such as 30° or 45°. Although Figure 2 The beam 220 is shown to propagate in a straight line to the substrate 10, but one or more mirrors can be positioned in the optical path of the beam 220.

[0044] Light source 212 can produce substantially monochromatic and / or collimated light. For example, light source 212 can be a laser, such as a laser with a wavelength in the visible light range of 400-700 nanometers, as this makes it easier to align the sensor. However, wavelengths in the infrared or ultraviolet range can also be used. Alternatively, light source 212 can also emit white light. For example, light source 212 can be a xenon lamp or a xenon-mercury lamp. Photodetector 164 can be a photodetector, for example, a detector that outputs a simple scalar signal representing the total light intensity. Alternatively, photodetector 164 can output multiple signals, each for a different wavelength range.

[0045] Depending on the circumstances, one or more optical fibers may be used to transmit light from the light source 212 to a location below the substrate, and / or to transmit light reflected from the substrate 10 to the detector 214. For example, a branched optical fiber may be used to transmit light from the light source 212 to the substrate 10 and back to the detector 214.

[0046] The groove detection station 200 may include a mechanism for adjusting the vertical height of the optical components from which the light beam is directed directly onto the substrate 10. For example, the optical components (including mirrors, if present) may be supported on an optical plate or frame 240. An actuator 242 may adjust the vertical position of the optical plate or frame 240. In some embodiments, the actuator 242 may also include an XY actuator system comprising two independent linear actuators for independently moving the optical plate or frame 240 along two orthogonal axes. If an optical fiber is used, the actuator 242 may adjust the position of one end of the fiber.

[0047] In some specific embodiments, the shield 230 may be positioned between the carrier head 140 and the optical components (e.g., light source 212 and detector 214) of the optical recess detector 210 to prevent liquids that may be present on the substrate 10 or retaining ring 142 from dripping onto and contaminating the optical components. In this case, the beam 220 and the reflected beam 222 pass through the window 232 in the shield 230. The top surface of the shield 230 may be coplanar with the top surface of the platform 120.

[0048] Purifying gas 234 can be guided from outlet 236 across the bottom surface of window 232. This removes droplets from the bottom of window 232, preventing condensation and fogging. The purifying gas can be nitrogen or filtered air.

[0049] Alternatively, the purified gas can be directed to the impact spot 224. The purified gas can be a humid gas, such as the humid gas produced by passing deionized water and filtered air through the atomizer.

[0050] The output of circuit system 216 can be a digital electronic signal transmitted to controller 190 for analysis. Similarly, light source 212 can be turned on or off according to control commands in the digital electronic signals transmitted from controller 190 to optical groove detector 210. Alternatively, circuit system 216 can communicate with controller 190 via wireless signals.

[0051] For some processes, orienting each substrate to a consistent angular position before polishing begins is highly useful. If the polishing operation has some inherent angular variations, such as due to feature patterns on the substrate, a consistent starting angular position can improve the ability to compensate for these variations, for example, by applying different pressures through the chambers within the bearing head. Furthermore, a consistent starting angular position increases the likelihood that the sensor 180 can track a series of consistent paths on the substrate on an inter-wafer basis, thereby making signal processing from the in-situ monitoring system more reliable.

[0052] The substrate 10 to be polished typically includes grooves that allow the substrate 10 to be angularly oriented, for example, at a specific angle to the groove. Reference marks are generally defined by removing a portion of the substrate. For example, such as... Figures 4A-4B As shown, the circular substrate 10 may have a groove 12 formed by removing a portion from the substrate edge 14. The diameter D1 of the substrate 10 may be 200 mm or 300 mm. Figure 4A As shown, the groove 12 can be triangular in shape. Such a groove 12 can be relatively small, for example, its depth from the substrate edge 14 does not exceed 1 mm, and its width along the circumferential direction does not exceed 1 mm (for clarity, ...). Figure 4A (The dimensions in the text are clearly exaggerated). Or, as... Figure 4B As shown, groove 12' can be a "plane".

[0053] Back Figure 3 During operation, the carrier head 140 is placed in the groove detection station 200, with the substrate 10 positioned above and spaced apart from the optical components of the optical groove detector 210. Specifically, the carrier head 140 is positioned such that the beam 220 strikes the substrate 10 on the impact spot 224 at the edge 16 of the contact or overlap substrate. The carrier head 140 rotates, causing the substrate 10 to rotate as well, thereby sweeping the beam along the circumference of the substrate 10. Since the reflectivity of the diaphragm 144 will differ from that of the substrate 10, the signal of the detector 214 should change when the groove 12 passes through the beam 220.

[0054] Assuming the beam scans along the circumference of the substrate, a uniform signal will be generated, except for changes in the location of the grooves. However, the reality is more complex. First, during the loading operation at the transfer station, the center of the substrate may not be precisely aligned with the rotation axis of the carrier head. Second, during polishing, the substrate 10 may be laterally driven by the frictional force from the polishing pad and come into contact with the retaining ring 142. Therefore, referring to... Figure 5The center point 16 of the substrate 10 may be offset from the rotation axis 152 of the carrier head. This causes the substrate edge 14 to be closer to the inner diameter surface 143 of the retaining ring 142 in one region (e.g., point 18a) and farther away from the inner diameter surface 143 of the retaining ring 142 in the opposite region (e.g., point 18b). This difference can be greater than the depth of the groove 12, for example, 0.5-4 mm. Therefore, in order for the beam 220 to reliably capture the groove 12, the beam needs to be wide enough so that the groove 12 falls within the impact spot 224, regardless of the angular position of the substrate 10 relative to the carrier head 140. Therefore, the impact spot 224 may need to have a radial width of about 1-10 mm, for example, the diameter D2 of a circular impact spot is 5-10 mm.

[0055] Ideally, the position of the carrier head should prevent the impact spot 224 from overlapping with the retaining ring 142 of the carrier head. However, the carrier head can be positioned such that the impact spot 224 overlaps with the retaining ring 142. In this case, the retaining ring will contribute to signal generation. However, since the retaining ring rotates around the rotation axis 152, this contribution should remain constant with the angular orientation of the carrier head.

[0056] Now for reference Figure 5 and Figure 6 As the carrier head rotates, the impact spot 224 of the beam will scan along the edge of the substrate 10 (as shown by arrow A). Therefore, the percentage of the impact spot 224 reflected from the substrate 10 will change as the carrier head rotates.

[0057] Generally, the reflectivity of the diaphragm can be expected to be lower than that of the substrate 10. Therefore, at the angle α1 where the substrate 10 is farthest from the fixing ring 142, the reflected light should be at its minimum I. MIN Conversely, at the angle α2 closest to the fixing ring 142 on the substrate 10 (which should deviate from α1 by 180°), the reflected light should be at its maximum I. MAX At other positions between α1 and α2, the reflected light should be at I. MIN and I MAX The variations between these values ​​generate a signal in the form of a 250° sine wave from the sensor, such as... Figure 6 As shown. In Figure 5 and Figure 6 In the example, the reflection intensity of the substrate first decreases and then increases from angle α0. However, this is not necessary; the phase of the sine wave 250 relative to the starting position α0 depends on the position of the nearest point 18a along the circumference of the substrate 10.

[0058] When the bearing head is at the angle position α where the impact spot 224 overlaps with the groove 12 X At that time, the intensity of the reflected light should decrease by 252. Since the groove 12 is relatively small compared to the impact spot 224, the intensity difference ΔI can be less than the amplitude of the sine wave 250 (IMAX -I MIN ).

[0059] However, various techniques can still be used to detect this drop in signal strength 252, thereby detecting the angular position α of the groove 12. X For example, the first derivative of the reflected light intensity signal can be monitored, and the controller can detect where the first derivative exceeds a threshold. Where the first derivative exceeds the threshold, it indicates the presence of a groove 12. As another example, the second derivative of the reflected light intensity signal can be monitored, and the controller can detect where the second derivative exceeds a threshold. Where the second derivative exceeds the threshold, it indicates the presence of a groove 12. As yet another example, a sine function can be fitted to the signal from the sensor; this sine function can be subtracted from the signal, and the difference can be analyzed to detect a drop of 252. Furthermore, the signal can be processed through a high-pass filter.

[0060] Although Figure 6 The diagram illustrates a smooth sine wave 250, but in reality, the signal can be affected by noise. Examples of distortion or noise include the sensing channel passing through a portion of the mounting ring (or the edge of the carrier head), the presence of water droplets in dry measurements or air bubbles in wet measurements, wafer pattern noise, electrical / sensor noise, and mechanical and alignment noise. These noises can be partially or completely filtered out through appropriate signal processing. For example, the signal can be passed through one or more filters, such as a low-pass filter.

[0061] The encoder output signal of drive shaft 156 indicates the angular position of some arbitrary (but fixed) points on the drive shaft. Once the angular position α of the bearing head detecting the groove is known... X This allows us to calculate the angular offset Δα of the groove 12 relative to the bearing head. The fixed point may be located at α0; in this case, Δα = α. X But to put it more simply, Δα = α F -α X .

[0062] Given the known angular offset Δα, the carrier head can be rotated to orient the substrate 10 into the desired initial substrate angle α before the polishing process (e.g., before lowering the substrate 10 to contact the polishing pad). D For example, the bearing head can be rotated to the initial bearing head angle α. S , where α S =α D -Δα.

[0063] Figure 7A specific embodiment of an optical notch detector 210 is shown. The optical notch detector 210 includes two light sources 212a and 212b and a beam combiner 246. The light sources 212a and 212b generate light beams of different wavelengths, and the beam combiner 246 combines the light beams into a single incident beam 220. For example, the first light source 212a can generate infrared light, while the second light source 212b can generate blue light.

[0064] For patterned substrates, excessive noise may be introduced at certain wavelengths due to the pattern. However, this noise can be reduced by selecting appropriate wavelengths. There should be a consistently optimal wavelength for a given pattern. Controller 190 causes optical recess detector 210 to sequentially scan substrate 10 using each light source 212a, 212b, and then determines which light source provides a signal with lower noise. In some embodiments, light sources can be combined or selected individually for better performance. Controller 190 can then monitor other substrates with the same pattern using the light source or source. That is, controller 190 maintains a database storing identification information for different patterns, each pattern associated with a light source or wavelength.

[0065] Figure 8 An embodiment of an optical notch detector 210 is shown, which includes a camera 260 having a field of view 262 over a substrate 10. In this embodiment, when the substrate 10 is at the notch detection station 20, the camera 260 can capture images or image sequences of the substrate 10. In the illustrated embodiment, the field of view 262 covers the entire substrate 10. However, if the field of view is smaller than the substrate 10, image combining can be used to construct a complete image of the substrate; this may involve rotation and scanning of the carrier head.

[0066] The controller 190 can use image processing technology on the image or image sequence to determine the position of the groove, thereby determining the angular orientation of the substrate 10.

[0067] In some embodiments, the controller 190 may use image processing techniques to determine the angular orientation of patterns (e.g., scribing lines and chips) on the substrate. This can provide an initial estimate of the substrate's angular orientation, which can then be refined by probing the location of the recesses.

[0068] Figure 9An optical groove detector is shown, which guides the light beam 220 through a water column. In this specific embodiment, the branched fiber has two branch ends, connected to a light source and a detector respectively, and a main stem 270 located inside a tube 272. Liquid 274, such as deionized water, can be drawn into and pass through the tube 272 from a liquid source 276. During measurement, a substrate 10 can be positioned on the main stem end of the fiber. The height of the substrate 10 relative to the top of the tube 272 and the flow rate of the liquid 274 are selected such that when the liquid 274 overflows the tube 272, it fills the space between the fiber end 270 and the substrate 10.

[0069] Figure 10 An optical recess detector 210 is shown, wherein at least one surface of the substrate is lowered into a storage tank 280. The recess detector station 200 includes a housing or basin 292 containing a liquid 294. A portion of the substrate 10 and the support head, such as the bottom surface of the retaining ring 142, may be immersed in the liquid 284, such as deionized water, in the storage tank 280. Figure 10 The thickness of substrate 10 is exaggerated; in practical applications, the back surface of the substrate is likely to be lower than the surface 284a of the liquid 284 in the storage tank 280. The backbone end 270 of the optical fiber can extend into the storage tank 280 through the housing 292, positioned near the edge of substrate 10.

[0070] exist Figure 9 or Figure 10 In either case, during operation, light originates from the light source, passes through liquid 274 or 284 to reach the surface of substrate 10, is reflected from the surface of substrate 10, enters the backbone end 270 of the optical fiber, and then returns to the detector.

[0071] Although the above description focuses primarily on groove detection stations with optical groove detectors that utilize the intensity of reflected light or imaging, other types of sensors can also be used for groove detectors.

[0072] For example, a groove detector can use a confocal microscope or laser displacement measurement. A confocal microscope or laser displacement sensor can be used to measure the height profile of a scanned area along the circumference of a substrate. The height difference between the bottom surface of the substrate and the bottom surface of the diaphragm or other backing surfaces holding the substrate can be detected. This indicates the location of the groove feature.

[0073] As another example, a notch detector can use capacitive sensing technology. In this example, the notch detector is a capacitive sensor that can detect notches by analyzing the capacitance signal generated when the sensor scans along the circumference of the substrate.

[0074] The polishing apparatus and method described above can be applied to various polishing systems. The platform can be around a track instead of rotating. The polishing pad can be a circular (or other shaped) pad fixed to the platform. The polishing layer can be a standard polishing material (e.g., polyurethane with or without a filler layer), a soft material, or a fixed abrasive material.

[0075] The controllers and other computing devices in the systems described herein can be implemented using digital electronic circuit systems, or using computer software, firmware, or hardware. For example, a controller may include a processor for executing a computer program stored in a computer program product, such as a computer program stored on a non-transitory, machine-readable storage medium. Such a computer program (also referred to as a program, software, software application, or program code) can be written in any form of programming language, including compiled or interpreted languages, and can be deployed in any form, including as a standalone program or as a module, component, subroutine, or other unit suitable for use in a computing environment.

[0076] In the case of a controller, “configuration” means that the controller has the necessary hardware, firmware, or software or combination thereof to perform the required functions during operation (rather than simply performing the required functions through programming).

[0077] Some specific embodiments have been described. However, it is understood that various modifications can be made without departing from the spirit and scope of this description. Therefore, other specific embodiments are also within the scope of the following claims.

Claims

1. A polishing apparatus, the polishing apparatus comprising: Multiple stations, including a first station and a second station, wherein the first station is a polishing station or a conveying station, and the second station is a polishing station; A support head for holding a substrate, the support head being movable along a path from the first station to the second station via an actuator; A motor, the motor being used to rotate the bearing head about a rotation axis; A groove detection station is positioned on the path between the first station and the second station. The groove detection station includes a sensor that generates a signal based on the proportion of the sensor's sensing area covered by the substrate. as well as Controller, the controller is configured for The actuator positions the carrier head, thereby positioning the substrate at the groove detection station, so that the sensing area of ​​the sensor is located at the edge of the substrate. The motor rotates the carrier head, causing the sensing area of ​​the sensor to scan along the circumference of the substrate. The sensor detects the angular position of a groove in the edge of the substrate based on a signal, including compensating for the sinusoidal component of the signal caused by the center of the substrate deviating from the axis of rotation.

2. The apparatus of claim 1, wherein the sensor comprises an optical sensor, the optical sensor comprising a light source and a detector, the light source being configured to generate a light beam impacting the surface of the substrate, and the detector being configured to detect reflected light and generate a signal indicating the intensity of the reflected light.

3. The apparatus of claim 2, wherein the optical sensor is configured at an oblique angle.

4. The apparatus of claim 2, wherein the optical sensor is configured to generate a light beam that strikes the surface of the substrate and is perpendicular to the surface.

5. The apparatus of claim 2, wherein the light source comprises a laser.

6. The apparatus of claim 2, wherein the light source comprises a plurality of light sources that generate light beams with different wavelengths.

7. The apparatus of claim 6, wherein the controller is configured to select a light source from the plurality of light sources according to a pattern on the substrate.

8. The apparatus of claim 1, wherein the sensor comprises a capacitive sensor.

9. The apparatus of claim 1, wherein the sensor comprises a confocal microscope.

10. The apparatus of claim 1, wherein the sensor comprises a laser displacement sensor.

11. The apparatus of claim 1, wherein the first station is a polishing station.

12. The apparatus of claim 1, wherein the first station is a transmission station.

13. The apparatus of claim 1, wherein the controller is configured to compensate the sinusoidal component of the signal by monitoring a first derivative of the signal and detecting that a portion of the first derivative exceeds a threshold.

14. The apparatus of claim 1, wherein the controller is configured to compensate the sinusoidal component of the signal by monitoring a second derivative of the signal and detecting a portion of the second derivative that exceeds a threshold.

15. The apparatus of claim 1, wherein the controller is configured to compensate for the sinusoidal component of the signal by subtracting a sinusoidal function from the signal.

16. The apparatus of claim 15, wherein the sine function is fitted to the signal before being subtracted from the signal.

17. The apparatus of claim 1, wherein the controller is configured to compensate for the sinusoidal component of the signal by applying a high-pass filter to the signal to remove the sinusoidal component.

18. The device according to claim 1, wherein the radial width of the sensing area is 5-10 mm.

19. The apparatus of claim 1, wherein the sensing area is substantially circular.

20. The apparatus of claim 1, wherein the controller is configured to position the actuator on the carrier head such that the substrate is positioned such that the sensing does not overlap with the retaining ring of the carrier head.

21. A method comprising the following steps: The substrate is held in the carrier head, and the substrate is positioned such that the sensing area of ​​the sensor of the groove detection station is located at the edge of the substrate; Rotate the carrier head to rotate the substrate, so that the sensing area of ​​the sensor scans along the circumference of the substrate; as well as The angular position of the groove in the edge of the substrate is detected based on the signal from the sensor, including compensation for the sinusoidal component of the signal caused by the center of the substrate deviating from the axis of rotation.

22. A groove detection station, comprising: A sensor for generating a signal that depends on the proportion of the sensor's sensing area covered by a substrate; as well as Controller, the controller is configured to The actuator positions the carrier head relative to the substrate, while the sensing area of ​​the sensor is located at the edge of the substrate. The motor generates relative motion between the carrier head and the sensor, thereby causing the sensing area of ​​the sensor to scan along the circumference of the substrate. Based on the signal emitted by the sensor, the angular position of the groove in the edge of the substrate is detected, including compensating for the sinusoidal component of the signal caused by the center of the substrate deviating from the axis of rotation.

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