Control of vapor generation for chemical mechanical polishing

Abstract

To provide control of steam generation for a substrate processing tool for chemical mechanical polishing.SOLUTION: A chemical mechanical polishing system includes: a steam generator 410 with a heating element for applying heat to a vessel in order to generate steam; an opening for delivering steam onto a polishing pad; a first valve in a fluid line between the opening and the vessel; a sensor 260 for monitoring a steam parameter; and a control system 200. The control system causes the valve to open and close in accordance with a steam delivery schedule in a recipe, receives a measured value of the steam parameter from the sensor 260, receives a target value of the steam parameter, and performs a proportional integral derivative control algorithm with the target value and measured value as inputs so as to control the first valve and / or a second pressure release valve and / or the heating element so that the measured value reaches the target value substantially just before the valve is opened according to the steam delivery schedule.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] This disclosure relates, for example, to the control of vapor generation for substrate processing tools for chemical mechanical polishing (CMP). [Background technology]

[0002] Integrated circuits are typically formed on a substrate by continuously depositing conductive, semiconductive, or insulating layers onto a semiconductor wafer. Various manufacturing processes require planarization of the layers on the substrate. For example, one manufacturing process involves depositing a filler layer on a non-planar surface and then polishing the filler layer until the top surface of the patterned layer is exposed. Another example is depositing a layer on top of a patterned conductive layer and planarizing it to enable subsequent photolithography steps.

[0003] Chemical mechanical polishing (CMP) is one of the recognized planarization methods. This method typically requires a substrate to be placed on a carrier head. The exposed surface of the substrate is usually positioned relative to a rotating polishing pad. The carrier head applies a controllable load to the substrate, pressing it against the polishing pad. Typically, a polishing slurry containing abrasive particles is supplied to the surface of the polishing pad.

[0004] The removal rate during polishing can be sensitive to temperature. Various techniques have been proposed to control the temperature during polishing. [Overview of the project]

[0005] The chemical mechanical polishing system includes a steam generator comprising a platen for supporting a polishing pad, a carrier head for holding a substrate in contact with the polishing pad, a motor for generating relative motion between the platen and the carrier head, a vessel having a water intake and a steam outlet, and a heating element configured to heat a portion of the lower chamber to generate steam, an arm extending across the platen having at least one opening oriented to supply steam onto the polishing pad from the steam generator, a first valve in the fluid line between the opening and the steam outlet for controllably connecting and disconnecting the opening and the steam outlet, a sensor for monitoring steam parameters, and a control system optionally connected to the sensor, the valve, and the heating element. The control system is configured to open and close the valve according to a steam supply schedule in a polishing process recipe stored as data in a non-temporary memory device, receive measured values ​​of steam parameters from the sensor, receive target values ​​of steam parameters, and execute a proportional-integral-derivative control algorithm with the target value and measured value as input to control the first valve and / or second pressure relief valve and / or heating element such that the measured value reaches the target value approximately immediately before the valve opens according to the steam supply schedule.

[0006] Possible benefits may include, but are not limited to, one or more of the following:

[0007] Steam, i.e., gaseous H2O generated by boiling, can be generated in sufficient quantity to allow steam heating of the polishing pads before polishing each substrate, and the steam can be generated at a constant pressure between wafers. The temperature of the polishing pads, and consequently the polishing temperature, can be controlled and made more uniform between wafers, resulting in reduced wafer-to-wafer non-uniformity (WIWNU). Energy efficiency can be improved by minimizing the generation of excess steam. The steam can be a substantially pure gas, for example, a gas with little or no suspension in it. Such steam, also known as dry steam, can provide gaseous H2O with higher energy transfer and less liquid content than other steam alternatives such as flash steam.

[0008] Details of one or more implementation configurations are specified in the attached drawings and the following description. Other embodiments, features, and advantages will become apparent from these descriptions and drawings, as well as from the claims. [Brief explanation of the drawing]

[0009] [Figure 1A] This is a schematic cross-sectional view of an example of a polishing station in a polishing apparatus. [Figure 1B] This is a schematic top view of an exemplary polishing station in a chemical mechanical polishing apparatus. [Figure 2] This document describes a control system that includes a proportional-integral-differential control algorithm that can be implemented to control the power supplied to a steam generator. [Figure 3A] This is a schematic cross-sectional view of an exemplary steam generator. [Figure 3B] This is a schematic upper cross-sectional view of an exemplary steam generator. [Modes for carrying out the invention]

[0010] Chemical mechanical polishing works through a combination of mechanical polishing and chemical etching at the interface between the substrate, polishing fluid, and polishing pad. During the polishing process, a considerable amount of heat is generated due to friction between the substrate surface and the polishing pad. In addition, some processes include an in-pad conditioning step. In this in-pad conditioning step, a conditioning disc (e.g., a disc coated with polishing diamond particles) is pressed against a rotating polishing pad to prepare and smooth the surface of the polishing pad. Heat can also be generated by the polishing during the conditioning process. For example, in a typical 1-minute copper CMP process with a nominal downforce pressure of 2 psi and a removal rate of 8000 Å / min, the surface temperature of the polyurethane polishing pad can rise by approximately 30°C.

[0011] On the other hand, if the polishing pad is heated by the previous polishing operation, when a new substrate is first lowered to contact the polishing pad, the polishing pad will be at a lower temperature and can therefore act as a heat sink. Similarly, the slurry distributed onto the polishing pad can also act as a heat sink. Overall, these effects result in spatial and temporal fluctuations in the temperature of the polishing pad.

[0012] For example, both chemical reaction-related variables in the CMP process (e.g., variables as the initiation and rate of the reactions involved) and mechanical-related variables (e.g., the surface friction coefficient and viscoelasticity of the polishing pad) are highly dependent on temperature. As a result, fluctuations in the surface temperature of the polishing pad can lead to changes in removal rate, polishing uniformity, corrosion, dishing, and residue. By more precisely controlling the surface temperature of the polishing pad during polishing, temperature fluctuations can be reduced, which can improve polishing performance, for example, as measured in terms of in-wafer non-uniformity or inter-wafer non-uniformity.

[0013] One technique proposed to control the temperature in a chemical mechanical polishing process is to spray steam onto the polishing pad. Steam can sometimes be superior to hot water because, for example, due to the latent heat of steam, less steam may be required to impart the same amount of energy as hot water.

[0014] In a typical polishing process, vapor is supplied in a duty cycle that can range from 1% to 100% (typically measured as the percentage of the total time from the start of polishing one wafer to the start of polishing a subsequent wafer). When the duty cycle is less than 100%, the vapor generation cycle can be divided into two sections: a recovery phase and a supply phase.

[0015] Typically, during the recovery phase, the steam-generating vessel is considered closed; that is, the valve is closed so that steam cannot escape from the vessel. Power is applied to a heater (e.g., a resistance heater), and thermal energy is injected into the liquid water in the vessel. Furthermore, the liquid water may flow into the vessel and replace the water lost in the previous dispensing cycle.

[0016] During the dispensing phase, a valve is opened to allow steam to be dispensed. During the dispensing phase, the steam generator may not be able to keep up with the steam flow rate. In this case, the dispensing phase is accompanied by a pressure drop in the container. Under certain circumstances, when heated liquid water is exposed to the atmosphere, a rapid phase change of the gas, commonly known as flash steam, can occur.

[0017] Generally, during the recovery phase, the goal is to add sufficient thermal energy to prepare steam for the next dispensing phase, as defined by the parameters (temperature, flow rate, pressure) required for the process. In some cases, for example, if an 80 - second recovery phase follows a 20 - second dispensing phase, the required steam pressure can be comfortably achieved before the start of the next dispensing cycle. In this scenario, the power to the heater may be turned off to avoid exceeding the parameters (such as pressure) for which steam is required. However, since the container is not a perfect insulator, some heat loss may occur, and the steam may not remain at the desired parameters. Alternatively, to maintain the required parameters (such as pressure), the power to the heater can be maintained, and excess steam can be released (e.g., vented). However, this results in excessive energy consumption and poor energy efficiency. [[ID=!]]

[0018] To address this issue, during the recovery phase, the control system can control the power applied to the heater using, for example, a proportional - integral - derivative control algorithm so that the parameters required just before the start of the next dispensing phase are achieved.

[0019] Figures 1A and 1B show an example of a polishing station 20 of a chemical mechanical polishing system. The polishing station 20 includes a rotatable disk - shaped platen 24 on which a polishing pad 30 is placed. The platen 24 is operable to rotate about an axis 25 (see arrow A in Figure 1B). For example, a motor 22 can rotate a drive shaft 28 to rotate the platen 24. The polishing pad 30 can be a two - layer polishing pad having an outer polishing layer 34 and a softer backing layer 32. <@

[0020] The polishing station 20 can include a supply port, for example, at the end of a slurry supply arm 39 to dispense a polishing liquid 38, such as a polishing slurry, onto the polishing pad 30. The polishing station 20 can further include a pad conditioner with a conditioning disk to maintain the surface roughness of the polishing pad 30.

[0021] The carrier head 70 is operable to hold the substrate 10 against the polishing pad 30. The carrier head 70 is suspended from a support structure 72 (e.g., a carousel or a track), and is connected to a carrier head rotation motor 76 by a drive shaft 74, whereby the carrier head 70 can rotate about the axis 71. Alternatively, the carrier head 70 can vibrate laterally, for example, on a slider on the carousel, by movement along a track or by rotational vibration of the carousel itself.

[0022] The carrier head 70 may include a flexible membrane 80 having a substrate mounting surface that contacts the back side of the substrate 10, and a plurality of pressurizable chambers 82 that apply various pressures to various zones of the substrate 10 (e.g., various radial zones). The carrier head 70 may include a holding ring 84 for holding the substrate. In some implementations, the holding ring 84 may include a lower plastic portion 86 that contacts the polishing pad and an upper portion 88 of a harder material (e.g., metal).

[0023] During operation, the platen rotates about its central axis 25, and the carrier head rotates about its central axis 71 (see arrow B in FIG. 1B) and moves laterally across the upper surface of the polishing pad 30 (see arrow C in FIG. 1B).

[0024] In some implementations, the polishing station 20 includes a temperature sensor 64 for monitoring the temperature within the polishing station, or the temperature of a component of the polishing station or a component within the polishing station (e.g., the temperature of the polishing pad 30 and / or the slurry 38 on the polishing pad). For example, the temperature sensor 64 may be an infrared (IR) sensor (e.g., an IR camera) positioned above the polishing pad 30 and configured to measure the temperature of the polishing pad 30 and / or the slurry 38 on the polishing pad. In particular, the temperature sensor 64 may be configured to measure the temperature at a plurality of points along the radius of the polishing pad 30 to generate a radial temperature profile. For example, the IR camera may have a field of view that spans the radius of the polishing pad 30.

[0025] In some implementations, the temperature sensor is a contact sensor rather than a non-contact sensor. For example, the temperature sensor 64 may be a thermocouple or IR thermometer positioned on or within the platen 24. Furthermore, the temperature sensor 64 can be in direct contact with the polishing pad.

[0026] In some implementations, multiple temperature sensors may be spaced apart at various radial positions along the polishing pad 30 to provide temperature at multiple points along the radius of the polishing pad 30. This technique can be used instead of, or in addition to, an IR camera.

[0027] In Figure 1A, the temperature sensor 64 is shown positioned to monitor the temperature of the polishing pad 30 and / or the slurry 38 on the pad 30, but it may be positioned inside the carrier head 70 to measure the temperature of the substrate 10. The temperature sensor 64 may be in direct contact with the semiconductor wafer of the substrate 10 (i.e., it may be a contact sensor). In some implementations, for example, multiple temperature sensors are included in the polishing station 22 to measure the temperatures of various components of the polishing station or various components within the polishing station.

[0028] The polishing system 20 further includes a temperature control system 100 for controlling the temperature of the polishing pad 30 and / or the slurry 38 on the polishing pad. The temperature control system 100 includes a heating system 104 that operates by supplying steam, i.e., a temperature-controlled medium, onto the polishing surface 36 of the polishing pad 30 (or the polishing fluid already present on the polishing pad). In particular, the medium includes steam from, for example, a steam generator 410 (see Figure 2A). The steam may be mixed with another gas (e.g., air) or liquid (e.g., heated water), or the medium may be substantially pure steam. In some embodiments, additives or chemicals are added to the steam.

[0029] The medium can be supplied, for example, by passing it through an aperture such as a hole or slot provided by one or more nozzles on a heating supply arm. The aperture can be provided by a manifold connected to the source of the heating medium.

[0030] An exemplary heating system 104 includes an arm 140 extending across the platen 24 and the polishing pad 30 from the edge of the polishing pad 30 to the center of the polishing pad, or at least near there (e.g., within 5% of the total radius of the polishing pad). The arm 140 may be supported by a base 142, which may be supported on the same frame 40 as the platen 24. The base 142 may include one or more actuators, for example, a linear actuator for raising or lowering the arm 140, and / or a rotary actuator for swinging the arm 140 laterally over the platen 24. The arm 140 is positioned to avoid collisions with other hardware components such as the polishing head 70, the pad conditioning disc 92, and the slurry dispensing arm 39.

[0031] Multiple openings 144 are formed on the bottom surface of the arm 140. Each opening 144 is configured to guide a gas or steam, for example, steam, onto the polishing pad 30. The arm 140 can be supported by a base 142 such that the openings 144 are separated from the polishing pad 30 by gaps 126. The gaps 126 can be 0.5 to 5 mm. In particular, the gaps 126 can be selected so that the heat of the heated fluid does not dissipate significantly before the fluid reaches the polishing pad. For example, the gaps can be selected so that the steam released from the openings does not condense before reaching the polishing pad.

[0032] The heating system 104 may include a steam source, for example, a steam generator 410. The steam generator 410 is connected to an opening 144 in the arm 140 by a fluid supply line 146. The fluid supply line 146 may be provided by piping, a flexible tube, a passage through a solid providing the arm 140, or a combination thereof.

[0033] The steam generator 410 includes a water-holding container 420 and a heater 430 for supplying heat to the water in the container 420. Power can be supplied to the heater 430 from a power supply 250. A sensor 260 may be placed inside the container 420 or in the fluid delivery line 146 to measure the physical parameters of the steam (e.g., temperature or pressure).

[0034] In some implementations, processing parameters (e.g., flow rate, pressure, temperature, and / or liquid-gas mixing ratio) can be controlled independently for each nozzle. For example, the fluid for each opening 144 can flow through individually controllable heaters to individually control the temperature of the heated fluid (e.g., the temperature of the steam).

[0035] Various openings 144 can guide the vapor 148 onto various radial zones 124 on the polishing pad 30. Adjacent radial zones may overlap. Optionally, some of the openings 144 can be oriented such that the central axis of the spray from the opening is oblique to the polishing surface 36. The vapor can be guided from one or more of the openings 144 such that it has a horizontal component in the direction opposite to the direction of motion of the polishing pad 30 in the impact area caused by the rotation of the platen 24.

[0036] Figure 1B shows that the openings 144 are spaced equally apart, but this is not mandatory. The nozzles 120 may be unevenly distributed radially, angularly, or both. For example, the openings 144 may be more densely clustered toward the center of the polishing pad 30. As another example, the openings 144 may be more densely clustered at a radius corresponding to the radius through which the slurry supply arm 39 supplies the polishing fluid 39 to the polishing pad 30. Furthermore, although Figure 1B shows nine openings, there may be more or fewer openings.

[0037] When steam is generated (for example, in the steam generator 410 in Figure 2A), the temperature of the steam 148 can be between 90°C and 200°C. For example, if the steam is supplied by the nozzle 144 due to heat loss during passage, the temperature of the steam can be between 90°C and 150°C. In some implementations, the steam supplied by the nozzle 144 is between 70°C and 100°C (e.g., 80°C and 90°C). In some implementations, the steam supplied by the nozzle is superheated (i.e., its temperature exceeds its boiling point (for its pressure)).

[0038] When steam is supplied by nozzle 144, the steam flow rate can be 1 to 1000 cc / min depending on the heater output and pressure. In some implementations, the steam is mixed with other gases, for example, a normal atmosphere or N2. Alternatively, the fluid supplied by nozzle 120 is substantially pure water. In some implementations, the steam 148 supplied by nozzle 120 is mixed with liquid water, for example, aerosolized water. For example, liquid water and steam can be combined in a relative flow rate ratio of 1:1 to 1:10 (e.g., a flow rate of sccm). However, if the amount of liquid water is low (e.g., less than 5% by weight, e.g. less than 3% by weight, e.g. less than 1% by weight), the steam will have excellent heat transfer properties. Therefore, in some implementations, the steam is dry steam, i.e., substantially free of water droplets.

[0039] The polishing system 20 may further include a cooling system (e.g., an arm having an aperture for distributing a cooling fluid onto the polishing pad), a high-pressure rinsing system (e.g., an arm having a nozzle for spraying rinsing fluid onto the polishing pad), and a wiper blade or wiper body for uniformly distributing the polishing fluid 38 over the polishing pad 30.

[0040] Referring to Figure 2, the polishing system 20 includes a control system 200 for controlling the operation of various components (e.g., a temperature control system 100), as well as the rotation of the carrier head, the rotation of the platen, and the pressure applied by the chamber within the carrier head.

[0041] The control system 200 may be configured to receive pad temperature measurements from the temperature sensor 64. The control system implements a first control loop 202 in which target parameters for steam can be set for each cycle (each cycle includes a recovery phase and a dispensing phase, as described above). Briefly, the control loop 202 can compare the measured pad temperature with a target pad temperature and generate a feedback signal. The feedback signal is used to calculate a modified target parameter for steam to reach the target pad temperature. For example, if the measured pad temperature did not reach the target pad temperature in the previous dispensing phase, the feedback signal causes the temperature control system 200 to supply more heat to the polishing pad in the subsequent dispensing phase, but if the measured pad temperature exceeded the target pad temperature in the previous dispensing phase, the feedback signal causes the temperature control system 200 to supply less heat to the polishing pad in the subsequent dispensing phase.

[0042] Several techniques can be used individually or in combination to control the amount of heat supplied to the polishing pad at each dispensing stage. Firstly, the period during which steam is supplied, for example, the duty cycle, may be extended (to supply more heat) or shortened (to supply less heat). Secondly, the temperature at which the steam is supplied may be increased (to supply more heat) or decreased (to supply less heat). Thirdly, the pressure at which the steam is supplied may be increased (to supply more heat) or decreased (to supply less heat).

[0043] Therefore, if the measured pad temperature does not reach the target pad temperature, the feedback signal can instruct the control loop 202 to increase the target steam temperature, pressure, and / or duty cycle for the subsequent dispensing stage. On the other hand, if the measured pad temperature exceeds the target pad temperature in the previous dispensing stage, the feedback signal can instruct the control loop 202 to decrease the target steam temperature, pressure, and / or duty cycle. As a result, the target values ​​for steam parameters r(t), such as the target values ​​for pressure or temperature, may change from cycle to cycle. In some implementations, the control loop can operate continuously rather than cycle to continuously monitor the temperature of the polishing pad 30 and adjust the target values ​​for parameters r(t) as polishing progresses.

[0044] The parameter target value r(t) is output from the control loop 202 to the proportional-integral-derivative (PID) controller 204. This controller executes a proportional-integral-derivative control algorithm to control the power applied to the heater 430 by the power supply 250. The PID controller 204 may be connected to a sensor 260 to receive a measured value Y(t) of a parameter (e.g., temperature or pressure). The PID controller 204 can be adjusted so that the target parameter value is achieved immediately before the start of the next dispensing stage. For example, the target parameter can be reached less than 180 seconds (e.g., less than 60 seconds, less than 30 seconds, less than 10 seconds, less than 3 seconds, less than 1 second) before the valve opens.

[0045] In the PID controller 204, the target parameter value r(t) is compared with the parameter value Y(t) measured from the sensor 260 by the comparator 210. The comparator outputs an error signal e(t) based on the difference.

[0046] The error signal is input to the proportional value calculator 212, which calculates the first proportional output P. The proportional output P is, It can be calculated based on TIFF0007911094000001.tif11170, where K Pis the weight set during adjustment. The error signal e(t) is also input to the integral value calculator 214 that calculates the second integral output I. The integral output I can be calculated based on TIFF0007911094000002.tif16170, where K I is the weight set during adjustment. The error signal e(t) is also input to the derivative value calculator 216 that calculates the third derivative output D. The integral output D can be calculated based on TIFF0007911094000003.tif17170, where K D is the weight set during adjustment. [[ID=|10]]

[0047] [[ID=|11]] The summation calculator 218 sums the proportional output P, the integral output I, and the derivative output D, and outputs the control signal u(t). The control signal u(t) sets the power that the power supply 250 outputs to the heater 430. [[ID=|14]]

[0048] [[ID=|15]] Generally, when adjusting the PID controller 204, it is desirable to keep K P as low as possible. Then, based on the overshoot and the settling time, K I and K D can be increased as needed so that the target parameter value is achieved just before the start of the next dosing phase. Various PID tuning methods are available, such as the Cohen-Coon method, the Ziegler-Nichols method, the Tyreus-Luyben method, and the Autotune method. In some implementations, the amount of heat applied is controlled under the assumption that the duty cycle of the valve is constant. In this case, the gain values K I K P and K D do not need to be changed for each cycle. However, in some implementations, if the duty cycle changes for each cycle, K I K P and K D can be adjusted for each duty cycle. For example, once the duty cycle is calculated, the gain values K I K P and KD The gain value can be selected based on a lookup table that associates it with the duty cycle percentage.

[0049] In some implementations, instead of controlling the heat added by the heater 430, the PID controller 204 can control a flow meter or valve 270 that can release pressure from the vessel in the steam generator 410. In this case, the flow meter or valve is controlled to release pressure and maintain the steam pressure at a target pressure value. When implemented as a valve, the valve may open and close on a duty cycle dependent on the control signal u(t). When implemented as a flow meter, the control signal u(t) can control the flow rate through the regulator, for example, by adjusting the aperture size. In some implementations, the PID controller 204 can control a valve 438, in which case the steam is discharged through an opening in the arm.

[0050] The control system 200 and its functional operation can be implemented in digital electronic circuits, tangibly embodied computer software or firmware, computer hardware, or a combination of one or more of these. The computer software can be implemented as one or more modules of computer program instructions encoded on a tangible, non-transient storage medium for execution by the processor of the data processing device, or for controlling the operation of the processor of the data processing device. The electronic circuits and data processing devices may include a general-purpose programmable, programmable digital processor and / or multiple digital processors or computers, and may also include dedicated logic circuits, such as FPGAs (field-programmable gate arrays) or ASICs (application-specific integrated circuits).

[0051] "Configured to" a control system to perform a particular operation or action means that, during operation, software, firmware, hardware, or a combination thereof is installed on the system that causes the system to perform that operation or action. "Configured to" a computer program to perform a particular operation or action means that the program, when executed by a data processing device, contains instructions that cause the device to perform that operation or action.

[0052] Referring to Figure 3A, steam for the processing described herein, or for other uses in chemical mechanical polishing systems, can be generated using a steam generator 410. An exemplary steam generator 410 may include a canister 420 surrounding an internal space 425. The walls of the canister 420 may be made of an insulating material (e.g., quartz) with very low levels of mineral contaminants. Alternatively, the walls of the canister may be formed of another material, for example, the inner surface of the canister may be coated with polytetrafluoroethylene (PTFE) or another plastic. In some implementations, the canister 420 may be 10 to 20 inches long and 1 to 5 inches wide.

[0053] Referring to Figures 3A and 3B, in some embodiments, the internal space 425 of the canister 420 is divided into a lower chamber 422 and an upper chamber 424 by a barrier 426. The barrier 426 can be made of the same material as the canister wall, for example, quartz, stainless steel, aluminum, or ceramic such as alumina. Quartz may be advantageous in that it has a low risk of contamination. The barrier 426 can substantially prevent liquid water 440 from entering the upper chamber 424 by blocking water droplets scattered by boiling water. This allows dry steam to accumulate in the upper chamber 424.

[0054] The barrier 426 includes one or more apertures 428. The apertures 428 allow steam to pass from the lower chamber 422 into the upper chamber 424. The apertures 428, and in particular the apertures 428 near the ends of the barrier 426, allow condensation on the walls of the upper chamber 424 to drip into the lower chamber 422, reducing the liquid content in the upper chamber 426 and making it possible to reheat the liquid with water 440.

[0055] The aperture 428 may be located at the end of the barrier 426 (e.g., only the end) where the barrier 426 contacts the inner wall of the canister 420. The aperture 428 may also be located near the end of the barrier 426 (e.g., between the end of the barrier 426 and the center of the barrier 426). This configuration may be advantageous in that the barrier 426 does not have an aperture in the center, thus reducing the risk of liquid droplets entering the upper chamber, and allowing condensation on the side walls of the upper chamber 424 to flow out of the upper chamber.

[0056] However, in some implementations, apertures are further positioned away from the edges, for example, across the entire width of barrier 426, or uniformly spaced across the area of ​​barrier 425.

[0057] Referring to Figure 3A, the water intake 432 can connect the water reservoir 434 to the lower chamber 422 of the canister 420. The water intake 432 may be located at or near the bottom of the canister 420 to supply water 440 to the lower chamber 422.

[0058] One or more heating elements 430 may surround a portion of the lower chamber 422 of the canister 420. The heating element 430 may be, for example, a heating coil (e.g., a resistance heater) wound around the outside of the canister 420. Furthermore, the heating element may be provided by a thin film coating on the material of the canister's side wall. When an electric current is applied, this thin film coating can function as a heating element.

[0059] The heating element 430 may be located in the lower chamber 422 of the canister 420. For example, the heating element may be coated with a material that prevents contaminants (e.g., metallic contaminants) from moving from the heating element into the vapor.

[0060] The heating element 430 can apply heat to the bottom of the canister 420 up to the minimum water level 443a. In other words, the heating element 430 can cover the portion of the canister 420 below the minimum water level 443a, thereby preventing overheating and reducing unnecessary energy consumption.

[0061] The steam outlet 436 can connect the upper chamber 424 to the steam supply passage 438. The steam supply passage 438 can be located at or near the top of the canister 420 (for example, on the ceiling of the canister 420). This allows steam to travel from the canister 420 through the steam delivery passage 438 to various components of the CMP apparatus. Using the steam supply passage 438, steam can be directed to various areas of the chemical mechanical polishing apparatus for steam cleaning and preheating of, for example, the carrier head 70, the substrate 10, and the pad conditioner disc 92.

[0062] In some implementations, the filter 470 is connected to a steam outlet 438 configured to reduce contaminants in the steam 446. The filter 470 may be an ion exchange filter.

[0063] Water 440 can flow from the water reservoir 434 through the water intake 432 into the lower chamber 422. Water 440 can fill the canister 420 to a water level 442 that is at least above the heating element 430 and below the barrier 426. When the water 440 is heated, a gaseous medium 446 is generated and rises through the aperture 428 of the barrier 426. The aperture 428 allows the vapor to rise and condensates to dissipate at the same time, resulting in a gaseous medium 446 in which water is substantially free of liquid (e.g., no liquid water droplets are suspended in the vapor).

[0064] In some implementations, the water level is determined using a water level sensor 460 that measures the water level 442 in the bypass pipe 444. The bypass pipe runs parallel to the canister 420 and connects the water reservoir 434 to the steam supply passage 438. The water level sensor 460 can indicate where the water level 442 is in the bypass pipe 444 and, consequently, in the canister 420. For example, since the water level sensor 444 and the canister 420 are equally pressurized (for example, both receive water from the same water reservoir 434, both have the same pressure above, and for example, both are connected to the steam supply passage 438), the water level 442 is the same between the water level sensor and the canister 420. In some embodiments, the water level 442 of the water level sensor 444 may indicate the water level 442 of the canister 420 in other situations, for example, the water level 442 of the water level sensor 444 is scaled to indicate the water level 442 of the canister 420.

[0065] During operation, the water level 442 in the canister is above the minimum water level 443a and below the maximum water level 443b. The minimum water level 443a is at least above the heating element 430, and the maximum water level 443b is well below the steam outlet 436 and barrier 426, so that there is enough space for the gaseous medium 446 (e.g., steam) to accumulate near the top of the canister 420 without substantially containing liquid water.

[0066] In some implementations, the controller 200 is connected to a valve 480 that controls the flow of fluid through the water intake 432, a valve 482 that controls the flow of fluid through the steam outlet 436, and / or a water level sensor 460. Using the water level sensor 460, the controller 200 is configured to control the flow of water 440 flowing into the canister 420 and the flow of gas 446 leaving the canister 420 to maintain a water level 442 above the minimum water level 443a (and above the heating element 430) and below the maximum water level 443b (and below the barrier 426, if present). The controller 200 may be further connected to a power supply 250 for the heating element 430 to control the amount of heat supplied to the water 440 in the canister 420.

[0067] We have described the measurement of pad temperature and the supply of steam to the pad, but these should be understood as including the measurement of slurry on the pad or the supply of steam to the slurry on the pad.

[0068] Several embodiments of the present invention have been described. However, it should be understood that various modifications are possible, as long as they do not deviate from the essence and scope of the invention. Therefore, other embodiments are also included in the following claims.

Claims

1. A computer program product comprising a computer-readable medium having instructions, wherein the instructions are configured for one or more processors. Allow access to polishing process recipes stored as data in a non-temporary memory device. A first valve between the outlet of a steam generating device and an opening directed to supply steam from the steam generating device onto the polishing pad is opened and closed according to a steam supply schedule which alternately repeats a recovery phase in which the first valve is closed and a dispensing phase in which the first valve is open. The steam generation device receives measured values ​​of its steam parameters from a sensor. The target value of the aforementioned steam parameter is received, Based on the target value and the measured value, the second pressure release valve and / or heating element is controlled such that the measured value reaches the target value approximately immediately before the first valve is opened according to the steam supply schedule. During the dispensing phase of one cycle, the first valve is opened, and during the recovery phase of one cycle, the first valve is closed. Computer program products.

2. The computer program product according to claim 1, wherein the steam parameter is steam temperature, the measured value is the measured steam temperature value, and the target value is the target steam temperature value.

3. The computer program product according to claim 1, wherein the steam parameter is steam pressure, the measured value is the measured steam pressure value, and the target value is the target steam pressure value.

4. The computer program product according to claim 1, comprising an instruction to control the second pressure release valve such that the measured value reaches the target value approximately immediately before the first valve is opened.

5. The computer program product according to claim 1, comprising an instruction to control the heating element such that the measured value reaches the target value approximately immediately before the first valve is opened.

6. The computer program product according to claim 1, comprising commands to control the second pressure release valve and / or the heating element such that the measured value reaches the target value less than 10 seconds before the first valve is opened.

7. The computer program product according to claim 1, comprising commands to control the second pressure release valve and / or the heating element such that the measured value reaches the target value less than three seconds before the first valve is opened.

8. The computer program product according to claim 1, comprising an instruction to control the second pressure release valve and / or the heating element such that the measured value reaches the target value less than one second before the first valve is opened.

9. The computer program product according to claim 1, which includes receiving a signal from a water level sensor and an instruction to modify the flow rate of water through the water intake based on the signal from the water level sensor so as to maintain the water level in the container above the heating element and below the outlet.

10. The computer program product according to claim 9, wherein each cycle corresponds to polishing a single substrate.

11. The computer program product according to claim 9, wherein each cycle consists of a single distribution stage and a single recovery stage.

12. The computer program product according to claim 1, which includes an instruction to receive a signal from a sensor representing the temperature of the polishing pad and to set the target value of the steam parameter based on the signal.

13. The computer program product according to claim 12, comprising an instruction to set the target value for each cycle.

14. The computer program product according to claim 12, comprising an instruction to continuously set the target value throughout one cycle.

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