Apparatus for processing wafers and method for controlling such an apparatus - Patents.com

Abstract

An apparatus for processing a wafer includes a rotatable chuck adapted to receive the wafer, a heating assembly including an array of heating elements configured to heat the wafer received by the rotatable chuck, an image sensor configured to detect electromagnetic radiation from a surface of the wafer, and a controller configured to control power supply to the array of heating elements based on the measurement output of the image sensor.

Description

[Technical field]

[0001] The present invention relates to an apparatus for processing wafers and to a method for controlling such an apparatus. [Background technology]

[0002] Semiconductor wafers may be subjected to various surface treatment processes such as etching, cleaning, polishing, material deposition, etc. To perform such processes, the wafer may be mounted on a rotatable chuck so that the various processes may be performed on the surface of the wafer.

[0003] For example, the surface of the wafer may be cleaned by applying a cleaning or rinsing liquid (e.g., isopropyl alcohol or deionized water) to the surface of the wafer. The surface of the wafer may then be dried by spinning the wafer using a rotatable chuck and heating the wafer to evaporate the cleaning or rinsing liquid. Such cleaning processes are commonly referred to as spin-clean processes.

[0004] An example of an apparatus that can be used to clean the surface of a wafer is described in U.S. Patent Application Publication No. 2017 / 0345681 A1, the contents of which are incorporated herein by reference.

[0005] The apparatus described in U.S. Patent Application Publication No. 2017 / 0345681 A1 includes a rotatable chuck on which a wafer can be placed, and a liquid dispenser for dispensing a liquid onto an upper surface of the wafer when the wafer is placed on the rotatable chuck. The apparatus also includes an array of heating elements disposed below the wafer and configured to heat the wafer when the wafer is placed on the rotatable chuck. After the liquid is dispensed onto the surface of the wafer, the array of heating elements is controlled to heat the wafer to evaporate the liquid. Summary of the Invention

[0006] Most generally, the invention provides an apparatus for processing a wafer, the apparatus comprising a heating element configured to heat a wafer mounted in the apparatus and an image sensor configured to detect electromagnetic radiation from a surface of the wafer, wherein power supply to the heating element is controlled based on a measurement output of the image sensor.

[0007] The processes performed on the wafer can be extremely sensitive to processing conditions such as temperature. The present invention allows for more precise control of the temperature of the wafer during processing because the heating elements used to heat the wafer are controlled based on the measurement output of an image sensor that detects electromagnetic radiation from the surface of the wafer.

[0008] For example, the measurement output of the image sensor may indicate the current temperature distribution across a portion or the entire wafer, and then based on the measurement output, the power supplied to the heating elements may be controlled to achieve a desired temperature distribution across a portion or the entire wafer.

[0009] A conventional technique for attempting to achieve a desired temperature distribution across a wafer during processing of the wafer is to manually set the power supplied to each heating element based on the desired temperature distribution. However, this is a long and cumbersome procedure. Moreover, this technique is not robust with respect to disturbances in the temperature distribution. For example, the heating caused by the heating elements may change over time, for example due to failure or degradation of one or more of the heating elements. This may lead to incorrect heating conditions being applied to the wafer and / or to heating conditions varying between different processing steps and / or between wafers. Other environmental factors that are difficult or impossible to adequately take into account in advance may also affect the temperature distribution across the wafer. For example, if a liquid is present on the surface of the wafer, the nature or properties of the liquid may vary across the surface of the wafer, thereby affecting the temperature distribution across the surface of the wafer.

[0010] The apparatus of the present invention can help address this challenge because the heating elements used to heat the wafer are controlled based on the measurement output of an image sensor that detects electromagnetic radiation from the surface of the wafer. For example, discrepancies between the actual temperature distribution of the wafer and the target temperature distribution of the wafer can be identified based on the measurement output of the image sensor and the power supplied to the heating elements controlled to eliminate or reduce any such discrepancies so as to achieve or substantially achieve the target temperature distribution.

[0011] Thus, according to a first aspect of the present invention, there is provided an apparatus for processing a wafer, the apparatus comprising a rotatable chuck adapted to receive a wafer, a heating assembly comprising an array of heating elements configured to heat the wafer received by the rotatable chuck, an image sensor configured to detect electromagnetic radiation from a surface of the wafer, and a controller configured to control power supply to the array of heating elements based on a measurement output of the image sensor.

[0012] As mentioned above, the image sensor is configured to detect electromagnetic radiation from the surface of the wafer. The power supplied to the heating elements is then controlled based on the measurement output of the image sensor. Thus, information indicative of the current temperature distribution of the wafer can be measured in situ, e.g., in real time, and used to control the heating elements so as to change the temperature distribution of the wafer, e.g., in real time.

[0013] Thus, the present invention may allow for more precise control of the temperature distribution of the wafer during processing.

[0014] The apparatus according to the first aspect of the invention may have any one, or any combination, of the following optional features.

[0015] In practice, the electromagnetic radiation detected by the image sensor represents or is indicative of the temperature of the surface of the wafer. For example, the intensity of the electromagnetic radiation may depend on the temperature of the surface of the wafer. For example, there may be a certain mathematical relationship between the intensity of the electromagnetic radiation and the temperature of the surface of the wafer.

[0016] The term "rotatable chuck" (or rotation chuck) can simply mean a wafer holder designed to hold a wafer and rotate the wafer.

[0017] The rotatable chuck may be configured to rotate the wafer about an axis of rotation of the rotatable chuck that is substantially perpendicular to a surface of the wafer.

[0018] The rotatable chuck may be substantially circular when viewed from above.

[0019] The rotatable chuck may include a mechanism (eg, clamps, screws, vacuum holders, etc.) adapted to receive a wafer and hold the wafer firmly in place relative to the chuck.

[0020] The rotatable chuck may be adapted to receive a wafer of a predetermined size (eg, a wafer having a diameter of 300 mm or 450 mm).

[0021] The rotatable chuck may include a motor for driving rotation of the chuck about the axis of rotation.

[0022] Alternatively, the rotatable chuck may be rotated by external drive means, for example via magnetic induction.

[0023] The heating assembly is responsible for heating a wafer mounted on the rotatable chuck. The heating assembly includes an array of heating elements configured to heat a wafer received by the rotatable chuck.

[0024] The term "array" may simply mean a plurality of heating elements and does not necessarily imply that the heating elements are arranged in any particular order.

[0025] When the wafer is received by the rotatable chuck, the array of heating elements may be configured to face toward the wafer.

[0026] The array of heating elements may be configured to face toward a first surface of the wafer opposite a second surface of the wafer on which processing (eg, cleaning, deposition of material, etc.) is performed.

[0027] The heating element may be disposed on a substantially flat surface (eg, on a substrate such as a circuit board).

[0028] When the wafer is received by the rotatable chuck, the substrate may be configured substantially parallel to the wafer.

[0029] The heating elements may be substantially uniformly distributed across the planar surface to provide uniform heating of the wafer.

[0030] When viewed from above, the heating assembly may have a circular shape.

[0031] The array of heating elements may be configured to cover an area substantially the same as the area of ​​the wafer, or within 10% of the area of ​​the wafer.

[0032] All of the heating elements may be of the same type (eg, they may all have the same characteristics).

[0033] The heating assembly may be mounted relative to the rotatable chuck such that the heating assembly does not rotate with the rotatable chuck when the rotatable chuck rotates about the axis of rotation. In other words, the array of heating elements may remain stationary when the rotatable chuck rotates about the axis of rotation. This may make it easier to provide electrical connections to the array of heating elements.

[0034] The heating elements may be arranged concentrically within the heating assembly (concentrically around the center of the heating assembly).

[0035] In each concentric circle, the heating elements may be bundled into different groups, in other words, the heating elements in each concentric circle may not be uniformly distributed around that concentric circle.

[0036] Each of the different groups may include the same number of heating elements, for example 16 heating elements.

[0037] In some embodiments, it may be possible to separately control individual groups of heating elements within the array.

[0038] Similarly, in some embodiments, it may be possible to control each individual heating element separately.

[0039] In general, a heating element is an element (or portion) operable to heat a wafer received by the rotatable chuck.

[0040] Any type of heating element may be used, for example radiative, conductive, or convective.

[0041] In some embodiments of the present invention, the heating elements may be light emitting heating elements configured to irradiate the wafer and heat the wafer.

[0042] In general, a light emitting heating element is an element (or part) that uses light to perform radiative heating.

[0043] The light emitted by the light emitting heating element may be visible light.

[0044] As used herein, a light-emitting heating element may refer to a light source that emits light at a wavelength suitable for heating a wafer. For example, a light-emitting heating element may emit light having a maximum intensity in the wavelength range of 380 nm to 650 nm.

[0045] In some embodiments, one or more of the light emitting heating elements may be a light emitting diode (LED).

[0046] The use of LEDs can be advantageous because they can be extremely efficient and generate relatively little wasted heat. The LEDs emit light at a wavelength or range of wavelengths suitable for heating the wafer. For example, the LEDs may emit light having a wavelength(s) in the range of 380 nm to 650 nm. Other wavelength ranges may also be suitable.

[0047] The image sensor is configured to detect electromagnetic radiation from the surface of the wafer.

[0048] As mentioned above, in practice, the electromagnetic radiation detected by the image sensor is electromagnetic radiation that is indicative of (eg, correlated with or proportional to) the temperature of the wafer.

[0049] The term "image sensor" simply means a two-dimensional array of sensors or sensing elements for measuring the intensity distribution of electromagnetic radiation over two dimensions.

[0050] The image sensor may output an image of the two-dimensional intensity distribution of the electromagnetic radiation, or information, eg a stream of data, representative of such two-dimensional intensity distribution.

[0051] The electromagnetic radiation may be emitted by the wafer itself or by one or more substances on the surface of the wafer. For example, the electromagnetic radiation may be emitted by a liquid on the surface of the wafer. References herein to the emission of electromagnetic radiation by the surface of the wafer expressly include the emission of electromagnetic radiation by other substances on the surface of the wafer, such as a liquid on the surface of the wafer.

[0052] The controller is configured to control power supply to the array of heating elements based on the measured output of the image sensor.

[0053] The controller may be a computing device having installed software for controlling the power supplied to the array of heating elements and receiving the measurement output of the image sensor.

[0054] The controller may be connected via a communication interface (e.g., USB, Ethernet, etc.) to a power supply that provides power to the array of heating elements. The controller may be configured to send commands to the power supply to control the power provided from the power supply to the array of heating elements. Similarly, the controller may be connected via a communication interface (e.g., USB, Ethernet, etc.) to an image sensor to receive measurement outputs from the image sensor.

[0055] For example, the controller may be configured to control the power supplied to the array of heating elements based on the measurement output of the image sensor until the measurement output indicates that a desired temperature distribution has been achieved, or substantially achieved, across a portion or the entire wafer.

[0056] The controller may be configured to compare the measurement output of the image sensor, or information derived from the measurement output, to a reference and adjust the power supplied to one or more of the heating elements of the array of light emitting heating elements based on the comparison.

[0057] The criterion may be related to the desired temperature distribution, for example, the criterion may correspond to an expected measurement output, or to a measurement output previously measured on a wafer having the desired temperature distribution, or to a target measurement output.

[0058] The controller may be configured to store the criteria in a memory.

[0059] The image sensor may be, for example, a thermographic image sensor, an infrared image sensor, or a thermal imaging image sensor.

[0060] The image sensor may be configured to detect infrared radiation.

[0061] The image sensor may be a camera, for example, the camera may generate an image of the electromagnetic radiation detected by the image sensor.

[0062] The camera may be, for example, a thermographic camera, an infrared camera, or a thermal imaging camera.

[0063] The image sensor may be adapted to detect electromagnetic radiation having a wavelength in the range of 3 to 14 μm, which corresponds to the so-called mid-wave infrared and long-wave infrared, which are indicative of temperature.

[0064] The image sensor may be adapted to detect electromagnetic radiation having a wavelength in the range of 3-5 μm, which corresponds to the so-called mid-wave infrared.

[0065] The image sensor may be adapted to detect electromagnetic radiation having a wavelength in the range of 8 to 14 μm, which corresponds to the so-called mid-wave infrared.

[0066] Such types of electromagnetic radiation may provide accurate information regarding (or indicative of) the temperature of the wafer, and therefore the measurement output of the image sensor may be used to accurately control the temperature of the wafer.

[0067] The image sensor may be adapted to detect electromagnetic radiation having a wavelength in a range where isopropyl alcohol (IPA) has a transmittance below 80%. This provides the advantage that, if IPA is present on the surface of the wafer, some, most or all of the electromagnetic radiation coming from below the IPA may be blocked by the IPA and therefore not detected by the image sensor. For example, the image sensor may be adapted to selectively detect a wavelength range that includes wavelengths in a range where isopropyl alcohol (IPA) has a transmittance below 80%. Alternatively, a filter may be provided that selectively transmits electromagnetic radiation having a wavelength in a range where isopropyl alcohol (IPA) has a transmittance below 80%, as described below.

[0068] The image sensor may be configured to detect electromagnetic radiation having a wavelength that corresponds to a peak in the emission intensity spectrum of isopropyl alcohol (IPA) or that corresponds to a minimum (local minimum or absolute minimum) in the transmission spectrum for isopropyl alcohol (IPA).

[0069] The apparatus may include a liquid dispenser for dispensing liquid onto the surface of the wafer.

[0070] For example, a liquid dispenser may be used to dispense isopropyl alcohol or deionized water onto the surface of the wafer to clean or rinse the surface of the wafer.

[0071] The liquid dispenser may be configured to dispense liquid onto a surface of the wafer opposite the surface facing the array of heating elements.

[0072] The liquid dispenser may be movable to dispense liquid at different locations on the surface of the wafer, so that liquid may be dispensed onto the surface of the wafer received on the rotatable chuck during the cleaning process.

[0073] The liquid dispenser may include an arm having a dispensing nozzle.

[0074] The arm may be pivoted to rotate at one end such that by rotating the arm about a pivot axis, the dispensing nozzle can be moved in an arc across the surface of the wafer.

[0075] The dispense nozzle may be movable between a first position at the center of rotation of the wafer and a second position outside the circumference of the wafer, and thus the dispense nozzle may be movable across the radius of the wafer.

[0076] The surface of the wafer may be dried by rotating the wafer using a rotatable chuck and heating the wafer to evaporate the liquid.

[0077] Thus, the apparatus of the present invention may be a spin-cleaning apparatus for spin-cleaning a wafer.

[0078] The controller may be configured to determine a temperature or temperature-related information at one or more locations on the surface of the wafer based on the measurement output of the image sensor, and control the supply of power to the array of heating elements based on the determined temperature or temperature-related information.

[0079] Controlling the power supplied to the array of heating elements Wafer The temperature at one of a number of locations on the surface of the device may be altered.

[0080] For example, temperature or temperature related information may be compared to previous measurements or to criteria related to predicted values ​​for a wafer having a desired temperature distribution or target value, any discrepancies may be identified, and power supplied to the array of heating elements may be controlled to reduce or eliminate any identified discrepancies. In this manner, the temperature distribution of the wafer may be controlled in real time to match or approach the desired temperature distribution.

[0081] The controller may be configured to determine a temperature distribution across any portion of the surface of the wafer based on the measurement output of the image sensor, or information related to such temperature distribution, and control the supply of power to the array of heating elements based on the determined temperature distribution or information related to the temperature distribution.

[0082] Each of the heating elements in the array of heating elements may be individually controllable, and the controller may be configured to individually control the power supplied to each of the heating elements, which may allow for more precise control of the temperature distribution across the wafer.

[0083] Alternatively, the array of heating elements may comprise multiple, individually controllable groups of heating elements, and the controller may be configured to individually control the power supplied to each of the multiple groups of heating elements.

[0084] In this way, each group of heating elements may be activated individually by providing power to that group by the controller, which may reduce the complexity of the device compared to controlling each of the heating elements individually.

[0085] When the wafer is received by the rotatable chuck, each group of heating elements may be configured to heat a different zone of the wafer.

[0086] The multiple heating element groups may be arranged concentrically about the axis of rotation of the rotatable chuck, with each group occupying a respective radial position, such that different radial zones of the wafer may be heated by activating different heating element groups.

[0087] The apparatus may comprise a filter adapted to selectively transmit electromagnetic radiation having a predetermined wavelength or range of wavelengths.

[0088] This aids in the detection of electromagnetic radiation having a certain wavelength by the image sensor, since other wavelengths of electromagnetic radiation, which may be caused by, for example, environmental noise, may be blocked by the filter.

[0089] "Selectively transmitting" can mean that the filter transmits only predetermined wavelengths, and / or transmits at most a predetermined percentage or amount of wavelengths less than the predetermined wavelength, and / or transmits at most a predetermined percentage or amount of wavelengths greater than the predetermined wavelength.

[0090] The filter may be, for example, a low pass filter, or a high pass filter, or a band pass filter.

[0091] The predetermined wavelength may be selected based on the thermal emission spectrum of the liquid used in processing the wafer.

[0092] The filter may be adapted to selectively transmit thermal radiation emitted by a liquid used in processing the wafer.

[0093] The filter may be adapted to selectively transmit thermal radiation emitted by the isopropyl alcohol.

[0094] For example, the filter may be adapted to selectively transmit thermal radiation having a characteristic wavelength emitted by isopropyl alcohol (IPA), such as the wavelength of a peak in the emission intensity spectrum of isopropyl alcohol (IPA).

[0095] The filter may be adapted to selectively transmit electromagnetic radiation having wavelengths in the range of 3.3 to 3.5 μm, or in the range of 8.6 to 9.1 μm, such wavelengths being characteristic wavelengths emitted by isopropyl alcohol (IPA).

[0096] The filter may be adapted to selectively transmit electromagnetic radiation having wavelengths in a range where the transmission of isopropyl alcohol (IPA) is below 80%. If IPA is present on the surface of the wafer, this provides the advantage that some, most, or all of the electromagnetic radiation coming from below the IPA may be blocked by the IPA and therefore not detected by the image sensor.

[0097] The filter may be configured to selectively transmit electromagnetic radiation having a wavelength that corresponds to a peak in the emission intensity spectrum of isopropyl alcohol (IPA).

[0098] The filter may be configured to selectively transmit electromagnetic radiation having a wavelength that corresponds to a minimum (either a local minimum or an absolute minimum) in the transmission spectrum of isopropyl alcohol (IPA).

[0099] In a spin-clean apparatus, when a rotatable chuck is rotated, the spinning of the wafer causes liquid on the surface of the wafer to move radially outward across the surface of the wafer, thus forming a dry line, which is a transition between dry and wet regions on the surface of the wafer, and which moves radially outward across the surface of the wafer.

[0100] When the liquid dispenser constantly dispenses liquid onto the surface of the wafer, the position of the dry line will be related to the position of the liquid dispenser. For example, if the dispense nozzle of the liquid dispenser is held in a fixed position, the position of the dry line will also be substantially fixed, but will actually be somewhat radially inward from the position of the liquid dispenser. When the dispense nozzle moves, the position of the dry line will move in conjunction with the movement of the dispense nozzle position.

[0101] When performing a spin clean of the wafer, the dispense nozzle may be moved to move radially outward across the surface of the wafer, in which case the dryness lines may track the movement of the dispense nozzle and move radially outward over the surface of the wafer.

[0102] As discussed in US Patent Application Publication No. 2017 / 0345681 A1, it is advantageous to preferentially heat the wafer (on the dry side of the dry line) in locations adjacent the dry line to a higher temperature than elsewhere on the surface of the wafer, thereby allowing the liquid in the dry line to dry more quickly and preventing pattern collapse phenomena that may otherwise occur during drying.

[0103] In an embodiment of the invention, the controller is configured to analyze the measurement output of the image sensor, or information derived from the measurement output, to determine a location of a dry line on the surface of the wafer corresponding to a transition between dry and wet regions, and to control the supply of power to the array of heating elements based on the determined location of the dry line.

[0104] The drying line may be substantially circular in shape about the axis of rotation of the wafer.

[0105] As discussed above, the radial position of the dry lines may be the same as, correspond to, or relate to the radial position where the liquid is dispensed on the surface of the wafer. Thus, if the location where the liquid is dispensed on the surface of the wafer moves radially outward across the surface of the wafer, the dry lines may also move radially outward across the surface of the wafer.

[0106] The controller may be configured to determine the location of the dryness line using an edge detection algorithm. There are many known suitable edge detection algorithms that may be used.

[0107] The controller is configured to control power to the array of heating elements such that the wafer is heated to a higher temperature at locations proximate the drying line than at other locations on the wafer, which, as described above, can help prevent pattern collapse phenomena while drying the wafer when the wafer is spin cleaned.

[0108] The controller is configured to control power to the array of heating elements such that the wafer is heated to a higher temperature at the dry side of the drying line, adjacent the drying line, than elsewhere on the wafer, which, as described above, can help prevent pattern collapse phenomena while drying the wafer.

[0109] The controller may be configured to control the heating elements to cause heating of a surface of the wafer along the radially moving circumferential front.

[0110] The radially moving circumferential front may maintain a fixed orientation relative to the drying line. For example, the radially moving circumferential front may maintain a fixed radial distance from the drying front, such as directly adjacent to the drying front on the dry side of the drying front. The radially moving circumferential front may track the radial movement of a dispensing nozzle dispensing liquid onto the surface of the wafer.

[0111] The controller may additionally control the array of heating elements to heat some or all of other portions of the wafer to a lower temperature.

[0112] The array of heating elements may be configured to heat a surface of the wafer opposite the surface of the wafer that is imaged by the camera.

[0113] The apparatus may further comprise a plate configured to be between the array of heating elements and the wafer when the wafer is received on the rotatable chuck, the plate may serve to protect the array of heating elements from processes being performed on the surface of the wafer.

[0114] The plate may be transparent and may be made, for example, of quartz or sapphire.

[0115] If the heating elements are light emitting heating elements, the transparent plate may be transparent to the light emitted by the light emitting heating elements.

[0116] The wafer may be a semiconductor wafer.

[0117] According to a second aspect of the present invention, there is provided a method of controlling an apparatus according to the first aspect of the present invention. The method of the second aspect of the present invention may include the features described above in relation to the first aspect of the present invention. These features will therefore not be repeated.

[0118] The method may include dispensing a liquid onto a surface of a wafer received by a rotatable chuck, rotating the rotatable chuck to remove liquid from the surface of the wafer during rotation, supplying power to an array of heating elements to heat the surface of the wafer, detecting electromagnetic radiation from the surface of the wafer with an image sensor, and adjusting power supplied to the array of heating elements based on the measured output of the image sensor. [Brief description of the drawings]

[0119] Embodiments of the present invention are discussed below with reference to the accompanying drawings. [Figure 1] FIG. 1 is a schematic cross-sectional view of an apparatus according to one embodiment of the present invention. [Figure 2a] FIG. 2a is a schematic illustration of the formation of dry lines on the surface of a wafer in an embodiment of the present invention. [Figure 2b] FIG. 2b is a schematic diagram of a heating temperature profile applied in the configuration shown in FIG. 2a in accordance with an embodiment of the present invention. [Diagram 3] FIG. 3 is an example of an infrared image from a wafer captured by an infrared camera in an embodiment of the present invention. [Figure 4a] FIG. 4a is an example plot of temperature versus radial distance taken from the image of FIG. [Figure 4b] FIG. 4b is a plot of the derivative of temperature versus radial distance for the example plot of FIG. 4a. [Diagram 5] FIG. 5 is an example of a heating assembly that may be used in embodiments of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0120] 1 shows a schematic cross-sectional view of an apparatus 100 for processing a wafer according to a first embodiment of the present invention, in which a wafer 101 is placed.

[0121] The apparatus 100 includes a rotatable chuck 102 adapted to receive a wafer. The rotatable chuck 102 includes a chuck body 104 rotatably mounted on a base 106. The chuck body 104 is rotatable relative to the base 106 about an axis of rotation indicated by reference numeral 108. Rotation of the chuck body 104 relative to the base 106 may be driven, for example, by a motor (not shown), which itself may be controlled by a controller. The chuck body 104 includes a set of gripping pins 110 adapted to receive the wafer 101 and hold the wafer 101 securely in place. Thus, when the wafer 101 is mounted on the rotatable chuck 102 via the gripping pins 110, the wafer 101 may be rotated by rotating the chuck body 104 relative to the base 106.

[0122] 1, the gripping pins 110 exert a gripping force to hold the wafer 101 in place. However, other suitable mechanisms may alternatively be used to hold the wafer 101 in place (e.g., clamps, screws, suction holders, etc.).

[0123] The rotatable chuck 102 further includes a plate 112 mounted on the chuck body 104. The plate 112 is fixed to the chuck body 104 such that the plate 112 rotates with the chuck body 104 relative to the base 106. As shown in Figure 1, the plate 112 is configured to be substantially parallel to the wafer 101 when the wafer 101 is mounted on the rotatable chuck 102. In this embodiment, the plate 112 is a transparent plate made of quartz or sapphire.

[0124] The apparatus 100 further comprises a heating assembly 114. In this embodiment, the heating assembly 114 comprises an array of LEDs 116 configured to illuminate a wafer mounted on the rotatable chuck 102. The LEDs 116 functions as a light emitting heating element for heating a wafer 101 received by a rotatable chuck 102.

[0125] In this embodiment, the LED 116 is configured to emit light in a wavelength range of 380 nm to 650 nm. For example, the LED 116 may emit light having a maximum intensity in the wavelength range of 380 nm to 650 nm. Such a wavelength range is suitable for heating a semiconductor wafer.

[0126] The transparent plate 112 is configured to be substantially transparent to the wavelengths emitted by the LEDs 116, i.e., all or most of the light emitted by the LEDs 116 is transmitted through the transparent plate 112.

[0127] The heating assembly 114 further comprises a plate 118. The array of LEDs 116 is mounted on an upper surface of the plate 118, and the plate 118 acts as a heat sink for the array of LEDs 116 to dissipate heat generated by the LEDs 116. For example, the plate 118 may be made of a metal such as aluminum. A circuit board 120 including driving circuitry (not shown) for the LEDs 116 is provided on a lower surface of the plate 118. Interconnections between the array of LEDs 116 and the driving circuitry on the circuit board are made through the plate 118. The plate 118 is mounted on a stationary post 122. The stationary post 122 is not connected to the chuck body 104 and therefore does not rotate with the chuck body 104. The plate 118 is substantially parallel to the transparent plate 112.

[0128] The array of LEDs 116 is configured to face toward the wafer 101 when the wafer is placed on the rotatable chuck 102. As shown in FIG. 1 , the transparent plate 112 is located between the array of LEDs 116 and the wafer 101 when the wafer is placed on the rotatable chuck 102. Thus, light emitted by the array of LEDs 116 may pass through the transparent plate 112 and impinge on the wafer 101, heating the wafer 101. The transparent plate 112 may serve to protect the array of LEDs 116 from a process performed on the wafer 101 when the wafer is placed on the rotatable chuck 102.

[0129] The array of LEDs 116 is configured to illuminate a first surface 103 of the wafer 101, opposite a second surface 105 of the wafer 101. The second surface 105 of the wafer 101 is exposed, and a process (e.g., etching, deposition of material, cleaning) may be performed on the second surface 105 of the wafer 101.

[0130] The array of LEDs 116 may be disposed substantially symmetrically about the axis of rotation 108 of the rotatable chuck 102. In this manner, the array of LEDs 116 may illuminate the wafer substantially symmetrically about the axis of rotation 108.

[0131] The apparatus 100 further comprises a liquid dispenser for dispensing liquid onto the second surface 105 of the wafer 101, for example to clean the second surface 105. In this embodiment, the liquid dispenser includes an arm 128 having a discharge nozzle 130. The arm 128 is supplied with process and / or rinsing liquid that is discharged downwardly through the discharge nozzle 130 onto the second surface 105 of the wafer 101.

[0132] The arm 128 is a swing arm 128 pivotally mounted at an end 128 of the arm opposite the end 128 of the arm at which the discharge nozzle 130 is located, such that the arm 128 can be rotated about the pivot mount to vary the position of the discharge nozzle 130 relative to the second surface 105 of the wafer 101. In particular, the pivot mount Department By rotating arm 128 about the center, the radial position of discharge nozzle 130 can be varied relative to second surface 105 of wafer 101, for example, between a first position at the center of second surface 105 of wafer 101 and a second position radially outward of the outer peripheral edge of wafer 101. Discharge nozzle 130 moves in an arc above second surface 105 of wafer 101.

[0133] The above-described liquid dispenser configuration, combined with rotation of the wafer 101 by the rotatable chuck 102, means that the liquid dispenser can be operated to dispense liquid across the entire second surface 105 of the wafer 101 by pivoting the arm 128 from the center of the second surface 105 to the edge of the second surface 105 while the wafer 101 is rotating.

[0134] Of course, in other embodiments, other suitable liquid dispensers may be substituted for this particular liquid dispenser.

[0135] As shown in FIG. 2a, as the discharge nozzle 130 of the arm 128 moves from the center of the second surface 105 of the wafer 101 to the edge of the second surface 105 while dispensing the liquid L and while the wafer 101 is rotating, a dry line 201 is generated that is a transition between the dry region 202 of the wafer and the wet region 203 of the wafer, and the dry line 201 moves radially outward across the second surface 105 of the wafer 101 in correlation with the movement of the discharge nozzle 130. For example, the dry line may be substantially circular in shape about the axis of rotation of the wafer 101. The radial position of the dry line 201 at any given time may correspond to the radial position of the discharge nozzle 130. In practice, the dry line is likely to be somewhat radially inward of the radial position of the discharge nozzle 130.

[0136] As discussed in U.S. Patent Application Publication No. 2017 / 0345681, when spin cleaning the surface of a wafer having high aspect ratio surface features, such as doped silicon fins, a pattern collapse phenomenon can occur when the liquid used in the spin cleaning dries out, damaging the high aspect ratio surface features.

[0137] For example, the surface tension of the cleaning or rinsing fluid (e.g., isopropyl alcohol (IPA)) and the high aspect ratio of the structures formed on the surface of the wafer may mean that the cleaning or rinsing fluid is pushed out of the spaces between the high aspect ratio structures more slowly, which can lead to the formation of a meniscus in the spaces between the structures. As drying continues, the surface tension of the cleaning or rinsing fluid may pull the structures towards each other, changing their shape and / or damaging or destroying the structures, which may impair or prevent proper performance of the associated semiconductor device.

[0138] US Patent Application Publication No. 2017 / 0345681 describes that the pattern collapse phenomenon can be reduced or prevented by preferentially heating the surface of the wafer to a higher temperature in locations close to the drying line. This localized higher temperature heating can serve to evaporate the cleaning or rinsing liquid quickly enough at the drying line so that a meniscus does not form between the high aspect ratio structures, thereby avoiding the pattern collapse phenomenon. As the drying line moves radially outward on the surface of the wafer, tracking the radial movement of the dispense nozzle, the localized higher temperature heating also moves radially outward on the surface of the wafer to track the movement of the drying line. Thus, a localized higher temperature front is created that moves radially outward across the surface of the wafer, tracking the movement of the dispense nozzle.

[0139] This type of heating is used in some embodiments of the present invention.

[0140] FIG. 2b illustrates an example of a heating profile that may be applied to the setup shown in FIG. 2a in accordance with one embodiment of the present invention.

[0141] 2b illustrates the temperature T to which the wafer 101 is heated by the heating assembly 114 versus radial position R on the wafer 101. The radial position R is the distance along the radial direction of the wafer 101 from the axis of rotation of the wafer 101.

[0142] The radial position of the drying line 201 is indicated using a dashed line in Figure 2b.

[0143] 2b shows a temperature profile along a single radial direction. In practice, the temperature profile may be the same or substantially the same along all radial directions (i.e., the temperature profile of the wafer may be rotationally symmetric or substantially rotationally symmetric). However, the temperature profile may be different in different radial directions due to environmental factors, etc.

[0144] As shown in FIG. 2b, in the wetted area 203, the liquid on the wafer 101 is heated to an elevated temperature 204, which is a temperature that does not cause premature drying of the liquid.

[0145] In contrast, in the dry regions 202 adjacent the drying line 201, the temperature of the wafer 101 is substantially increased to a temperature 205 where the evaporation rate of the cleaning or rinsing fluid is fast enough to prevent the formation of a meniscus (or a flat or 90 degree meniscus) between the high aspect ratio features, thereby avoiding the pattern collapse phenomenon described above.

[0146] As shown in FIG. 2b, in the remainder of the dry region 202, the already dried wafer is maintained at a lower, but still elevated, temperature 206 to ensure complete evaporation of the rinsing liquid and prevent condensation on the surface of the dried wafer.

[0147] Thus, in the present invention, a localized higher temperature front can be created that moves radially outward across the surface of the wafer.

[0148] The locally higher temperature front may be substantially ring-shaped across the second surface 105 of the wafer 101 .

[0149] Local Higher The radial location of the temperature front may correspond to the radial location of the dryness line on the surface of the wafer.

[0150] Local Higher The radial location of the temperature front may correspond to the radial location of the discharge nozzle 130 .

[0151] The apparatus 100 further comprises an image sensor in the form of an infrared camera 124 configured to detect infrared radiation from the second surface 105 of the wafer 101 .

[0152] 1, the infrared camera 124 is shown to be located above the axis of rotation of the wafer 101. Such positioning of the infrared camera 124 may mean that the infrared camera 124 can easily detect infrared radiation from the entire second surface 105 of the wafer 101. However, in other embodiments, the infrared camera 124 may be provided in a different position to detect infrared radiation from part or the entire second surface 105 of the wafer 101.

[0153] Infrared camera 124 detects a two-dimensional infrared intensity distribution from second surface 105 of wafer 101 .

[0154] The infrared camera 124 may be configured to detect infrared radiation having wavelengths in the range of 3-14 μm, or 3-5 μm, or 8-14 μm, or indeed any suitable wavelength range of infrared radiation.

[0155] The apparatus 100 may further include a controller (not shown) for controlling the power supplied to the array of LEDs 116 and for receiving the measurement output from the infrared camera 124 .

[0156] The controller may be any suitable computing device having software installed thereon to perform the necessary functions. For example, the controller may be connected to the circuit board 120 via a communication interface (e.g., USB, Ethernet, etc.) to control the amount of power provided to the array of LEDs 116. Similarly, the controller may be connected to the infrared camera 124 via a communication interface to receive measurement output from the infrared camera 124. The controller may include a memory in which various control parameters (e.g., power levels) for the array of LEDs 116 are stored. The controller may store the measurement data received from the infrared camera 124.

[0157] The LEDs 116 may be configured with multiple groups of LEDs 116 that are individually controllable. Each of the multiple groups of LEDs 116 may be independently powered, for example via circuitry on the circuit board 120, such that each group of LEDs 116 may be independently controlled (e.g., switched on or off). Each group of LEDs 116 may be configured to heat a specific zone of the wafer 101 such that different zones of the wafer 101 may be controllably heated. The multiple groups of LEDs 116 may be concentrically arranged around the axis of rotation 108 of the rotatable chuck 102 such that each group occupies a respective radial position. In this manner, different radial zones of the wafer 101 may be heated by activating different groups of LEDs 116.

[0158] The controller may be configured to automatically control the power supplied to the array of LEDs 116 based on the measurement output received from the infrared camera 124. For example, the controller may adjust the power supplied to the array of LEDs 116 until the measurement output indicates a desired temperature distribution on the second surface 105 of the wafer 101. If the array of LEDs 116 includes multiple groups of individually controllable LEDs 116, the controller may automatically adjust the power supplied to each of the groups of LEDs 116 such that a desired output is obtained for each group to achieve a desired temperature distribution on the surface 105 of the wafer 101.

[0159] In this embodiment, the controller is configured to determine a temperature distribution, or information related to the temperature distribution, across some or all of the surface 105 of the wafer 101 based on the measurement output from the infrared camera 124. The controller is further configured to control power supply to the array of LEDs 116 based on the determined temperature distribution, or information related to the temperature distribution.

[0160] For example, the controller may store in memory a target temperature distribution, or information regarding such target temperature distribution, for the second surface 105 of the wafer 101. Based on the measurement output from the infrared camera 124, any discrepancies between the current temperature distribution and the target temperature distribution may be identified. The power supplied to the LEDs 116 is then controlled such that the current temperature distribution substantially matches or corresponds to the target temperature distribution, thereby substantially eliminating or reducing any identified discrepancies.

[0161] If each LED 116 is individually controllable, the controller may control the power supplied to each LED 116 individually.

[0162] In contrast, if the LEDs are arranged into individually controllable groups, the controller may individually control the power supplied to each of the groups of LEDs 116.

[0163] In one embodiment of the present invention, the target temperature distribution for the second surface 105 of the wafer 101 may be similar to that shown in Figure 2b. For example, the target temperature distribution may include a localized (radially) higher temperature region directly adjacent the drying line 201, thereby heating the wafer 101 to a higher temperature in the vicinity of the drying line 201 to avoid or reduce pattern collapse phenomena.

[0164] In one embodiment of the present invention, the measurement output of the infrared camera 124 may be analyzed to determine the location of the drying lines 201 on the surface of the wafer. For example, the location of the drying lines 201 may be determined by applying an edge detection algorithm to the measurement output of the infrared camera 124.

[0165] Figure 3 is an example of the measurement output of infrared camera 124 in an embodiment of the present invention. The x and y axes in Figure 3 represent distance on the wafer's surface 101 in the perpendicular x and y directions, and the shading represents different intensities of infrared light detected from the wafer's surface 101 (lighter shading indicates higher temperature).

[0166] Figure 4a shows the variation of temperature with respect to distance along the solid line shown in Figure 3. Figure 4b shows the derivative of temperature with respect to distance in Figure 4a.

[0167] At the location of the dryness line 201 (dashed line in Figures 4a and 4b), there is an abrupt change in temperature of the second surface 105 of the wafer 101 due to the transition between dry areas of the surface and wet areas of the surface.

[0168] Therefore, the location of the dryness line can be determined by determining the location of the maximum of the derivative of temperature with respect to radial distance, as shown in Figure 4b.

[0169] Of course, in other embodiments, different techniques can be used to identify the location of the dry line.

[0170] Power to the array of LEDs 116 may then be controlled based on the determined location of the drying line 201. For example, as described above, power to the array of LEDs 116 may be controlled to create a localized area of ​​higher temperature directly adjacent (on the drier side of) the determined location of the drying line 201.

[0171] As the drying line 201 moves radially outward across the surface 105 of the wafer 101, e.g., tracking the radial movement of a dispensing nozzle, power to the array of LEDs 116 is also controlled to change the direction of the drying line. 201 , the localized higher temperature region may move radially outward across the surface 105 of the wafer 101 .

[0172] In this manner, a radially moving circumferential front of higher temperature may be produced by the LEDs 116 .

[0173] In an embodiment of the present invention, the liquid dispensed onto the second surface 105 of the wafer 101 is isopropyl alcohol (IPA), which may be used to clean or rinse the second surface 105 of the wafer 101 .

[0174] Infrared radiation emitted by objects other than the wafer's surface 101 may also be detectable by the infrared camera 124 and may interfere with the detection of infrared radiation from the wafer's surface 101. For example, infrared radiation may be emitted by other parts of the apparatus 100 or by other objects in the apparatus 100's environment.

[0175] To facilitate and / or accurately detect infrared radiation from surface 105 of wafer 101, apparatus 100 may include a filter (not shown) adapted to selectively transmit infrared radiation having a predetermined wavelength range. The filter is attached to or placed in close proximity to the aperture of infrared camera 124 such that all or a majority of the infrared radiation entering the aperture of infrared camera 124 first passes through the filter.

[0176] Preferably the filter is a bandpass filter, transmitting only a predetermined wavelength range of infrared radiation, however the filter may alternatively be a low pass or high pass filter.

[0177] In practice, the wavelengths transmitted by the filter will be selected based on the thermal emission spectrum of the liquid dispensed on the wafer, in particular the filter will be adapted to selectively transmit the thermal radiation emitted by the liquid dispensed on the wafer.

[0178] Thus, if the liquid dispensed onto the surface 105 of the wafer 101 is isopropyl alcohol (IPA), the filter would be adapted to selectively transmit the thermal radiation emitted by the isopropyl alcohol.

[0179] For example, the filter may be adapted to selectively transmit thermal radiation having a characteristic wavelength emitted by isopropyl alcohol (IPA), e.g., the wavelength of a peak in the emission intensity spectrum of isopropyl alcohol (IPA).

[0180] The filter may be adapted to selectively transmit electromagnetic radiation having wavelengths in the range of 3.3 to 3.5 μm, or in the range of 8.6 to 9.1 μm, such wavelengths being characteristic wavelengths emitted by isopropyl alcohol (IPA).

[0181] In practice, the semiconductor wafer is typically a semiconductor wafer.

[0182] An exemplary configuration of the heating assembly 114 in some embodiments of the present invention is shown in FIG.

[0183] 5, the LEDs 116 are arranged in concentric rings around the center of the heating assembly 114. The arrangement of LEDs 116 is rotationally symmetric about the center of the heating assembly 114.

[0184] In a given concentric ring, the LEDs 116 are bundled into groups 501, with each group 501 having 16 LEDs 116. In other words, in a given concentric ring, the LEDs 116 are not uniformly distributed around the concentric ring.

[0185] As mentioned above, the power to each group 501 of LEDs 116 may be controlled independently.

[0186] In this example, there are 20 concentric rings of LEDs 116, although of course in other embodiments the number of concentric rings may be different.

[0187] In FIG. 5, the heating assembly 114 is divided into four quadrants 502 that are joined by connectors 503 .

[0188] Each LED may have a power consumption of 10W and may provide an output of 3W.

[0189] Of course, the heating assembly 114 may differ from that shown in Figure 5. In particular, the arrangement of the LEDs in the heating assembly is not essential to the invention. <Application example 1> 1. An apparatus for processing a wafer, comprising: a rotatable chuck adapted to receive a wafer; a heating assembly including an array of heating elements configured to heat a wafer received by the rotatable chuck; an image sensor configured to detect electromagnetic radiation from a surface of the wafer; a controller configured to control power supply to the array of heating elements based on a measurement output of the image sensor. <Application example 2> An apparatus according to application example 1, wherein the image sensor is a camera. <Application example 3> The apparatus according to application example 2, wherein the camera is a thermal imaging camera. <Application Example 4> An apparatus according to any one of Application Examples 1 to 3, wherein the image sensor is adapted to detect electromagnetic radiation having a wavelength in the range of 3 to 14 μm. <Application example 5> An apparatus according to any one of application examples 1 to 4, comprising a liquid dispenser for dispensing liquid onto the surface of the wafer. <Application Example 6> An apparatus according to any one of Application Examples 1 to 5, which is a spin cleaning apparatus. <Application Example 7> The device according to any one of application examples 1 to 6, wherein the controller: determining a temperature, or information related to the temperature, at one or more locations on the surface of the wafer based on the measurement output of the image sensor; An apparatus configured to control power supply to the array of heating elements based on the determined temperature or the information related to the temperature. <Application Example 8> The device according to any one of application examples 1 to 7, wherein the controller: determining a temperature distribution, or information related to the temperature distribution, across all or some of the surface of the wafer based on the measurement output of the image sensor; An apparatus configured to control power supply to the array of heating elements based on the determined temperature distribution or information related to the temperature distribution. <Application Example 9> The device according to any one of application examples 1 to 8, each of the heating elements of the array of heating elements is individually controllable; The apparatus, wherein the controller is configured to individually control power supplied to each of the heating elements. <Application Example 10> The device according to any one of application examples 1 to 8, the array of heating elements comprises a plurality of groups of individually controllable heating elements; The apparatus, wherein the controller is configured to individually control power supplied to each of the plurality of groups of heating elements. <Application Example 11> An apparatus according to any one of Applications 1 to 10, comprising a filter adapted to selectively transmit electromagnetic radiation having a predetermined wavelength or range of wavelengths. <Application Example 12> The apparatus of application example 11, wherein the filter is a bandpass filter. <Application Example 13> 13. The apparatus of claim 11 or 12, wherein the filter is adapted to selectively transmit thermal radiation emitted by isopropyl alcohol. <Application Example 14> 14. The apparatus according to any one of Applications 11 to 13, wherein the filter is adapted to selectively transmit electromagnetic radiation having a wavelength in the range of 3.3 to 3.5 μm or in the range of 8.6 to 9.1 μm. <Application Example 15> 15. The device according to any one of application examples 1 to 14, wherein the controller: analyzing the measurement output of the image sensor to determine a location of a dry line on the surface of the wafer corresponding to a transition between dry and wet regions; An apparatus configured to control power supply to the array of heating elements based on the determined position of the dryness line. <Application Example 16> The apparatus of application example 15, wherein the controller is configured to determine the position of the drying line using an edge detection algorithm. <Application Example 17> The apparatus of any one of Application Examples 15 to 16, wherein the controller is configured to control the supply of power to the array of heating elements such that the wafer is heated to a higher temperature at a location proximate the drying line than at other locations on the wafer. <Application Example 18> An apparatus according to any one of Application Examples 1 to 17, wherein the controller is configured to control the heating elements to cause heating of the surface of the wafer along a radially moving circumferential front. <Application Example 19> An apparatus according to any one of Application Examples 1 to 18, wherein the array of heating elements is configured to heat a surface of the wafer opposite the surface of the wafer imaged by the camera. <Application Example 20> 20. The apparatus of any one of Application Examples 1 to 19, wherein the heating element is a light-emitting heating element configured to irradiate the wafer and heat the wafer. <Application Example 21> The device according to application example 20, wherein the light-emitting heating element is an LED. <Application Example 22> A method for controlling the device according to any one of application examples 1 to 21, comprising: Dispensing a liquid onto a surface of a wafer received by the rotatable chuck; rotating the rotatable chuck to remove liquid from the surface of the wafer; applying power to the array of heating elements to heat the surface of the wafer during said rotation; detecting electromagnetic radiation from the surface of the wafer using the image sensor; adjusting the power supplied to the array of heating elements based on the measured output of the image sensor.

Claims

1. 1. An apparatus for processing a wafer, comprising: a rotatable chuck adapted to receive a wafer; a heating assembly including an array of heating elements configured to heat a wafer received by the rotatable chuck; an image sensor configured to detect electromagnetic radiation from a liquid on a surface of the wafer; a controller configured to control power supply to the array of heating elements based on a measurement output of the image sensor; The controller: determining a temperature of the liquid on the surface of the wafer at one or more locations on the surface of the wafer based on the measurement output of the image sensor; and controlling power supply to the array of heating elements based on the determined temperature.

2. 1. An apparatus for processing a wafer, comprising: a rotatable chuck adapted to receive a wafer; a heating assembly including an array of heating elements configured to heat a wafer received by the rotatable chuck; an image sensor configured to detect electromagnetic radiation from a liquid on a surface of the wafer; a controller configured to control power supply to the array of heating elements based on a measurement output of the image sensor; The controller: determining a temperature distribution of the liquid on the surface of the wafer across a portion or the entire surface of the wafer based on the measurement output of the image sensor; and controlling power supply to the array of heating elements based on the determined temperature distribution.

3. 1. An apparatus for processing a wafer, comprising: a rotatable chuck adapted to receive a wafer; a heating assembly including an array of heating elements configured to heat a wafer received by the rotatable chuck; an image sensor configured to detect electromagnetic radiation from a liquid on a surface of the wafer; a controller configured to control power supply to the array of heating elements based on a measurement output of the image sensor; each of the heating elements of the array of heating elements is individually controllable; The apparatus, wherein the controller is configured to individually control power supplied to each of the heating elements.

4. 1. An apparatus for processing a wafer, comprising: a rotatable chuck adapted to receive a wafer; a heating assembly including an array of heating elements configured to heat a wafer received by the rotatable chuck; an image sensor configured to detect electromagnetic radiation from a liquid on a surface of the wafer; a controller configured to control power supply to the array of heating elements based on a measurement output of the image sensor; the array of heating elements comprises a plurality of groups of individually controllable heating elements; The apparatus, wherein the controller is configured to individually control power supplied to each of the plurality of groups of heating elements.

5. 1. An apparatus for processing a wafer, comprising: a rotatable chuck adapted to receive a wafer; a heating assembly including an array of heating elements configured to heat a wafer received by the rotatable chuck; an image sensor configured to detect electromagnetic radiation from a liquid on a surface of the wafer; a filter adapted to selectively transmit electromagnetic radiation having a predetermined wavelength or range of wavelengths; a controller configured to control power supply to the array of heating elements based on a measurement output of the image sensor.

6. 1. An apparatus for processing a wafer, comprising: a rotatable chuck adapted to receive a wafer; a heating assembly including an array of heating elements configured to heat a wafer received by the rotatable chuck; an image sensor configured to detect electromagnetic radiation from a liquid on a surface of the wafer; a controller configured to control power supply to the array of heating elements based on a measurement output of the image sensor; The controller: analyzing the measurement output of the image sensor to determine a location of a dry line on the surface of the wafer corresponding to a transition between dry and wet regions; and controlling power to the array of heating elements based on the determined location of the drying line such that the wafer is heated to a higher temperature at locations proximate the drying line than at other locations on the wafer.

7. 1. An apparatus for processing a wafer, comprising: a rotatable chuck adapted to receive a wafer; a heating assembly including an array of heating elements configured to heat a wafer received by the rotatable chuck; an image sensor configured to detect electromagnetic radiation from a liquid on a surface of the wafer; a controller configured to control power supply to the array of heating elements based on a measurement output of the image sensor; The apparatus, wherein the controller is configured to control the heating elements to cause heating of the surface of the wafer along a radially moving circumferential front.

8. 8. Apparatus according to any one of claims 1 to 7, wherein the image sensor is a camera.

9. 9. The apparatus of claim 8, wherein the camera is a thermal imaging camera.

10. 10. Apparatus according to any one of the preceding claims, wherein the image sensor is adapted to detect electromagnetic radiation having a wavelength in the range of 3 to 14 μm.

11. 11. Apparatus according to any one of claims 1 to 10, comprising a liquid dispenser for dispensing liquid onto the surface of the wafer.

12. 12. An apparatus according to any one of claims 1 to 11, which is a spin-cleaning apparatus.

13. 6. The apparatus of claim 5, wherein the filter is a bandpass filter.

14. 14. The apparatus of claim 5 or 13, wherein the filter is adapted to selectively transmit thermal radiation emitted by isopropyl alcohol.

15. 15. Apparatus according to claim 5, 13 or 14, wherein the filter is adapted to selectively transmit electromagnetic radiation having a wavelength in the range of 3.3 to 3.5 μm, or in the range of 8.6 to 9.1 μm.

16. 7. The apparatus of claim 6, wherein the controller is configured to determine the location of the drying line using an edge detection algorithm.

17. 17. The apparatus of claim 1, wherein the array of heating elements is configured to heat a surface of the wafer opposite the surface of the wafer imaged by the image sensor.

18. 18. The apparatus of claim 1, wherein the heating element is a light emitting heating element configured to irradiate the wafer to heat the wafer.

19. 20. The apparatus of claim 18, wherein the light emitting heating element is an LED.

20. A method for controlling a device according to any one of claims 1 to 19, comprising the steps of: Dispensing a liquid onto a surface of a wafer received by the rotatable chuck; rotating the rotatable chuck to remove liquid from the surface of the wafer; applying power to the array of heating elements to heat the surface of the wafer during said rotation; detecting electromagnetic radiation from a liquid on the surface of the wafer using the image sensor; adjusting the power supplied to the array of heating elements based on the measured output of the image sensor.

Images