TWI405905B - System and method for position control of a mechanical piston in a pump - Google Patents

Abstract

Embodiments of the systems and methods disclosed herein utilize a brushless DC motor (BLDCM) to drive a singie-stage or a multi-stage pump in a pumping system for real time, smooth motion, and extremely precise and repeatable position control over fluid movements and dispense amounts, useful in semiconductor manufacturing. The BLDCM may employ a position sensor for real time position feedback to a processor executing a custom field-oriented control scheme. Embodiments of the invention can reduce heat generation without undesirably compromising the precise position control of the dispense pump by increasing and decreasing, via a custom control scheme, the operating frequency of the BLDCM according to the criticality of the underlying function(s). The control scheme can run the BLDCM at very low speeds while maintaining a constant velocity, which enables the pumping system to operate in a wide range of speeds with minimal variation, substantially increasing dispense performance and operation capabilities.

Description

System and method for position control of a mechanical piston in a pump

The invention generally relates to fluid pumps. More specifically, embodiments of the present invention relate to systems and methods for position control of a mechanical piston in a motor-driven single or multi-stage pump suitable for use in semiconductor manufacturing.

There are many applications where precise control of the amount and/or rate of fluid being dispensed by the pumping device is necessary. For example, in semiconductor processing, it is important to control the amount and rate at which a photochemical such as a photoresist chemical is applied to a semiconductor wafer. Coatings applied to semiconductor wafers during processing typically require some flatness and/or uniform thickness across the surface of the wafer as measured in angstroms. The rate at which the chemical coating (i.e., dispensing) is applied to the wafer must be carefully controlled to ensure uniform application of the treatment liquid.

Photochemicals used in the semiconductor industry are now extremely expensive, costing up to $1000 per liter and more. Therefore, it is highly desirable to ensure that a minimum but sufficient amount of chemicals is used and that the chemicals are not damaged by the pumping device.

Unfortunately, these qualities are extremely difficult to achieve in today's pumping systems due to many related obstacles. For example, due to the supply issues introduced, the pressure can vary from system to system. Due to fluid dynamics and properties, the pressure needs to vary with different fluids (for example, fluids with higher viscosities require more pressure). In operation, vibrations from various parts of the pump system (eg, stepper motors) may adversely affect the performance of the pump system, particularly during the dispensing phase. In a pump system that utilizes a pneumatic pump, when a solenoid is present, it can cause large pressure spikes. In a multi-stage pump system, the small glitches in operation can also cause sharp pressure spikes in the liquid. These pressure spikes and subsequent pressure drops can damage the fluid (i.e., can adversely alter the physical characteristics of the fluid). In addition, pressure spikes can result in accumulated fluid pressure that can cause the dispensed pump to dispense more fluid than desired or dispense fluid in a manner that is unfavorable. In addition, because these obstacles are related, solving one obstacle can sometimes lead to many other problems and/or worsen the problem.

In general, the pump system does not satisfactorily control pressure changes in a cycle. There is a need for a novel pumping system that has the ability to provide instant smooth motion and extremely precise and repeatable position control of fluid movement and dispensing. In particular, there is a need for precise and repeatable position control of a mechanical piston in a pump. Embodiments of the present invention address these needs and more.

Embodiments of the present invention provide systems and methods for precise and repeatable position control of a mechanical piston in a pump that substantially eliminates or reduces previously developed pump systems and methods for use in semiconductor manufacturing Shortcomings. More specifically, embodiments of the present invention provide a pump system having a motor driven pump.

In one embodiment of the invention, the motor-driven pump is a dispensing pump.

In an embodiment of the invention, the dispensing pump can be part of a multi-stage or single-stage pump.

In one embodiment of the invention, a dual stage dispensing pump is driven by a permanent magnet synchronous motor (PMSM) and a digital signal processor (DSP) utilizing field oriented control (FOC).

In one embodiment of the invention, the dispensed pump is driven by a brushless DC motor (BLDCM) having a position sensor for instant position feedback.

Advantages of embodiments of the invention disclosed herein include the ability to provide immediate smooth motion and extremely precise and repeatable position control of fluid movement and dispensing.

One of the objectives of the present invention is to reduce heat generation without adversely damaging the precise positional control of the dispensed pump. This goal can be achieved in an embodiment of the invention by a custom control mechanism configured to increase the operating frequency of the position control algorithm of the motor for decisive functions (such as dispensing) and The operating frequency is reduced to the optimum range for non-deterministic functions.

Another advantage provided by embodiments of the present invention is enhanced speed control. The custom control mechanism disclosed herein allows the motor to operate at very low speeds while still maintaining a constant speed, which enables the novel pump system disclosed herein to operate with a minimum variation over a wide range of speeds, thereby generally Increased dispensing efficiency and operational capability.

The preferred embodiments of the present invention are described with reference to the drawings, which are not necessarily to

Embodiments of the present invention are directed to a pumping system having a multi-stage pump for feeding and dispensing fluid onto a wafer during semiconductor fabrication. Specifically, an embodiment of the present invention provides a pumping system for implementing a multi-stage pump, the multi-stage pump including a feed stage pump driven by a stepping motor and a brushless DC motor driven A graded pump is used for extremely accurate and repeatable control of fluid movement and dosing of fluid onto the wafer. It should be noted that the multi-stage pump as described herein and the pump system embodying the pump are provided by way of example only and not limitation, and embodiments of the invention may be implemented for other multi-stage pump groups state. Embodiments of a motor driven pump system with precise and repeatable position control will be described in more detail below.

1 is a schematic diagram of a motor assembly 3000 having a motor 3030 and a position sensor 3040 coupled thereto in accordance with an embodiment of the present invention. In the example shown in FIG. 1, diaphragm assembly 3010 is coupled to motor 3030 via lead screw 3020. In an embodiment, the motor 3030 is a permanent magnet synchronous motor ("PMSM"). In a brushed DC motor, the current polarity is varied by a rectifier and a brush. However, in the PMSM, polarity inversion is performed by a power transistor that is switched in synchronization with the rotor position. Therefore, the PMSM can be characterized as "brushless" and is considered to be more reliable than a brushed DC motor. In addition, the PMSM can achieve higher efficiency by generating rotor flux with a rotor magnet. Other advantages of PMSM include reduced vibration, reduced noise (by eliminating brushes), efficient heat dissipation, low footprint, and low rotor inertia. Depending on how the stator is wound, the anti-electromagnetic forces induced in the stator by the motion of the rotor may have different profiles. One profile may have a trapezoidal shape and the other profile may have a sinusoidal shape. Within the present disclosure, the term PMSM is intended to mean all types of brushless permanent magnet motors and can be used interchangeably with the term brushless DC motor ("BLDCM").

In an embodiment of the invention, the BLDCM 3030 can be used as a feed motor and/or a dosing motor in a pump such as the multi-stage pump 100 shown in FIG. In this example, multi-stage pump 100 can include a feed stage portion 105 and a separate dispense stage portion 110. The feed stage 105 and the dispense stage 110 can include a rolling diaphragm pump to pump fluid in the multi-stage pump 100. For example, the feed stage pump 150 ("Feed Pump 150") includes a feed chamber 155 for collecting fluid and a feed stage diaphragm 160 for moving within the feed chamber 155. And discharging the fluid; a piston 165 for moving the feed stage diaphragm 160; a lead screw 170; and a feed motor 175. The lead screw 170 is coupled to the feed motor 175 via a nut, a gear, or other mechanism for imparting energy from the motor to the lead screw 170. Feeding motor 175 rotates the nut, which in turn rotates lead screw 170, causing piston 165 to actuate. Feed motor 175 can be any suitable motor (eg, stepper motor, BLDCM, etc.). In one embodiment of the invention, feed motor 175 implements a stepper motor.

The dispensing stage 180 ("spreading pump 180") can include a dispensing chamber 185, a dispensing stage diaphragm 190, a piston 192, a lead screw 195, and a dispensing motor 200. The mating motor 200 can be any suitable motor, including a BLDCM. In one embodiment of the invention, the dispensing motor 200 implements the BLDCM 3030 of FIG. The mating motor 200 can be utilized by a digital signal processor ("DSP") using field oriented control ("FOC") at the dispensing motor 200, by a controller carried by the multi-stage pump 100, or by (eg , controlled by a separate pump controller outside the pump 100. The mating motor 200 can further include an encoder (e.g., a fine line rotational position encoder or position sensor 3040) for applying instant feedback of the position of the motor 200. The use of a position sensor imparts accurate and repeatable control of the position of the piston 192, which results in accurate and repeatable control of fluid movement in the dispensing chamber 185. For example, by using a 2000 line encoder that gives 8000 pulses to the DSP in accordance with an embodiment, it is possible to accurately measure the rotation to 0.045 degrees and control it at 0.045 degrees of rotation. In addition, BLDCM can operate at low speed with little or no vibration. The dispensing stage portion 110 can further include a pressure sensor 112 that determines the pressure of the fluid at the dispensing stage 110. The pressure determined by the pressure sensor 112 can be used to control the speed of various pumps. Suitable pressure sensors include ceramic-based and polymer-based piezoresistive and capacitive pressure sensors, including pressure sensors manufactured by Metallux AG of Korb, Germany.

From the point of view of fluid flow, a filter 120 is positioned between the feed stage portion 105 and the dispense stage portion 110 for filtering impurities from the process fluid. A number of valves (eg, inlet valve 125, isolation valve 130, barrier valve 135, purge valve 140, drain valve 145, and outlet valve 147) may be suitably positioned to control how fluid flows through the multi-stage pump 100. The valves of the multi-stage pump 100 are opened or closed to allow or restrict fluid flow to various portions of the multi-stage pump 100. These valves may be pneumatically actuated (e.g., gas actuated) diaphragm valves that open or close depending on whether pressure or vacuum is determined. Other suitable valves are possible.

In operation, the multi-stage pump 100 may include a ready section, a dispensing section, a filling section, a pre-filtration section, a filtration section, a discharge section, a purification section, and a static purification section (see FIG. 4). During the feed section, the inlet valve 125 is opened and the feed stage pump 150 moves (eg, pulls) the feed stage diaphragm 160 to draw fluid into the feed chamber 155. Once a sufficient amount of fluid has filled the feed chamber 155, the inlet valve 125 is closed. During the filtration section, the feed stage pump 150 moves into the stage diaphragm 160 to discharge fluid from the feed chamber 155. The isolation valve 130 and the barrier valve 135 are opened to allow fluid to pass through the filter 120 to the dispensing chamber 185. According to an embodiment, the isolation valve 130 may be first opened (eg, in a "pre-filter section") to allow pressure to be built into the filter 120, and then the barrier valve 135 is opened to allow fluid to flow into the dispensing chamber 185 . According to other embodiments, the isolation valve 130 and the barrier valve 135 can be opened and the feed pump can be moved to build pressure on the mating side of the filter. During the filtration section, the dispensing pump 180 can be brought to its home position. U.S. Provisional Patent Application Serial No. 60/630,384, entitled "SYSTEM AND METHOD FOR A VARIABLE HOME POSITION DISPENSE SYSTEM", filed on November 23, 2004, by Laverdiere et al. International Application No. PCT/US2005/042127 titled "SYSTEM AND METHOD FOR VARIABLE HOME POSITION DISPENSE SYSTEM", filed on November 21, 2005 by Laverdiere et al., and the corresponding US national phase application filed on September 30, 2008 As described in the pp. 11/666,124, the in-situ pump can be placed in the dispensing cycle with the maximum available volume at the dispensing pump but less than the maximum available volume available for the dispensing pump. The home position is selected based on various parameters of the dispense cycle to reduce the unused hold up volume of the multi-stage pump 100. The feed pump 150 can be similarly brought to an in situ position that provides a volume that is less than its maximum available volume.

As the fluid flows into the dispensing chamber 185, the pressure of the fluid increases. U.S. Patent Application Serial No. 11/292,559, entitled "SYSTEM AND METHOD FOR CONTROL OF FLUID PRESSURE", filed on December 2, 2005, by the name of the s. As described, the pressure in the dispensing chamber 185 can be controlled by adjusting the speed of the feed to the pump 150. In accordance with an embodiment of the present invention, when the fluid pressure in the dispensing chamber 185 reaches a predetermined pressure set point (e.g., as determined by the pressure sensor 112), the dispensing stage pump 180 begins to withdraw the dispensing stage diaphragm 190. . In other words, the dispensing stage pump 180 increases the available volume of the dispensing chamber 185 to allow fluid to flow into the dispensing chamber 185. This can be accomplished, for example, by reversing the dispensing motor 200 at a predetermined rate, resulting in a decrease in pressure in the dispensing chamber 185. If the pressure in the dispensing chamber 185 falls below the set point (within the tolerance of the system), the rate of feed into the motor 175 is increased to cause the pressure in the dispensing chamber 185 to reach the set point. If the pressure exceeds the set point (within the tolerance of the system), the rate of feed into the motor 175 is reduced, resulting in a decrease in pressure in the downstream dispensing chamber 185. The process of increasing and decreasing the speed of feeding into the motor 175 can be repeated until the dispensing stage pump reaches the home position, at which point the two motors can be stopped.

According to another embodiment, the speed of the first stage motor during the filter segment can be controlled using a "dead band" control mechanism. When the pressure in the dispensing chamber 185 reaches an initial threshold, the dispensing stage pump can move the dispensing stage diaphragm 190 to allow fluid to flow more freely into the dispensing chamber 185, thereby causing the dispensing chamber 185 The pressure in the decline. If the pressure drops below the minimum pressure threshold, the rate of feed into the motor 175 is increased, resulting in an increase in pressure in the dispensing chamber 185. If the pressure in the dispensing chamber 185 increases beyond the maximum pressure threshold, the rate of feed to the motor 175 is reduced. In addition, the process of increasing and decreasing the speed of feeding into the motor 175 can be repeated until the dispensing stage pump reaches the home position.

At the beginning of the discharge section, the isolation valve 130 is opened, the barrier valve 135 is closed and the discharge valve 145 is opened. In another embodiment, the barrier valve 135 can remain open during the discharge section and closed at the end of the discharge section. During this time, if the barrier valve 135 is open, the pressure can be learned by the controller because the pressure in the dispensing chamber that can be measured by the pressure sensor 112 will be affected by the pressure in the filter 120. The feed stage pump 150 applies pressure to the fluid to remove air bubbles from the filter 120 via the open discharge valve 145. The feed stage pump 150 can be controlled to cause emissions to occur at a predetermined rate, which allows for longer discharge times and lower discharge rates, thereby allowing for accurate control of the amount of waste discharged. If the feed pump is a pneumatic pump, fluid flow restriction can be made in the discharge fluid path, and the pressure applied to the feed pump can be increased or decreased to maintain the "emission" set point pressure, thereby giving another A certain control of the method being controlled.

At the beginning of the purge section, the isolation valve 130 is closed, the barrier valve 135 is closed (if it is open in the discharge section), the discharge valve 145 is closed, and the purge valve 140 is opened and the inlet valve 125 is opened. The dispensing pump 180 applies pressure to the fluid in the dispensing chamber 185 to vent air bubbles via the purge valve 140. During the static purge section, the dispensing of the pump 180 is stopped, but the purge valve 140 remains open to continue to vent the air. Any excess fluid removed during the purge or static purge section can be directed out of the multi-stage pump 100 (eg, back to the fluid source or discarded) or recycled to the feed stage pump 150. During the ready phase, the inlet valve 125, the isolation valve 130, and the barrier valve 135 can be opened and the purge valve 140 closed so that the feed stage pump 150 can reach the ambient pressure of the source (eg, the source bottle). According to other embodiments, all valves can be closed at the ready section.

During the dispensing section, the outlet valve 147 opens and the pump 180 is applied to apply pressure to the fluid in the dispensing chamber 185. Because the outlet valve 147 can react slowly to the control than the dispensing pump 180, the outlet valve 147 can be first opened and the dispensing motor 200 can be started after a predetermined period of time. This prevents the dispensing pump 180 from pushing fluid through the partially open outlet valve 147. In addition, this prevents fluid from moving upward along the dispensing nozzle (which is a micro-pull) caused by the opening of the valve, followed by movement of the fluid prior to the action of the motor. In other embodiments, the outlet valve 147 can be opened and the dispensing can begin at the same time by dispensing the pump 180.

An additional suckback section can be performed in which excess fluid in the dispensing nozzle is removed. During the suckback section, the outlet valve 147 can be closed and an auxiliary motor or vacuum can be used to draw excess fluid from the outlet nozzle. Alternatively, the outlet valve 147 can remain open and the dispensing motor 200 can be reversed to draw back fluid into the dispensing chamber. This suckback section helps prevent excess fluid from dripping onto the wafer.

FIG. 3 is an illustration of a pumping system 10 embodying a multi-stage pump 100. The pump system 10 can further include a fluid source 15 and a pump controller 20 that cooperates with the multi-stage pump 100 to dispense fluid onto the wafer 25. The operation of the multi-stage pump 100 can be controlled by the pump controller 20. The pump controller 20 can include a computer readable medium 27 (e.g., RAM, ROM, flash memory, compact disc, disk drive, or other computer readable medium) containing computer control medium 27 for controlling multiple levels A set of control commands 30 for the operation of the pump 100. The processor 35 (eg, a CPU, ASIC, RISC, DSP, or other processor) can execute the instructions. The pump controller 20 can be internal or external to the pump 100. In particular, the pump controller can reside on the multi-stage pump 100 or be connected to the multi-stage pump 100 via one or more communication links for communicating control signals, data or other information. As an example, the pump controller 20 is shown in FIG. 3 as being communicatively coupled to the multi-stage pump 100 via communication links 40 and 45. Communication links 40 and 45 can be networks (eg, Ethernet, wireless, global area networks, DeviceNet networks, or other networks known or developed in the art), busses (eg, SCSI) Bus) or other communication link. The pump controller 20 can be implemented as a self-contained PCB board, a remote controller, or in other suitable manners. The pump controller 20 may include a suitable interface (eg, a network interface, an I/O interface, an analog digital converter, and other components) to allow the pump controller 20 to communicate with the multi-stage pump 100. The pump controller 20 can include various computer components known in the art, including processors, memory, interfaces, display devices, peripheral devices, or other computer components. The pump controller 20 can control the various valves and motors in the multi-stage pump to cause the multi-stage pump to accurately dispense fluids, including low viscosity fluids (i.e., less than 100 centipoire) or other fluids. U.S. Provisional Patent Application Serial No. 60/741,657, entitled "I/O INTERFACE SYSTEM AND METHOD FOR A PUMP", filed on Dec. 2, 2005, by Cedrone et al. The description of the I/O interface connector described in U.S. Patent Application Serial No. 11/602,449, and the International Application No. PCT/US06/45127, filed on November 20, 2006, can be used to connect the pump controller 20 I/O adapters for various interfaces and manufacturing tools.

4 provides an illustration of the timing of the various stages of the operation of the multi-stage pump 100 and the timing of the dispensed motor. While several valves are shown as being simultaneously closed during a segment change, the closing of the valve can be timed slightly (eg, 100 milliseconds) to reduce pressure spikes. For example, between the discharge section and the purge section, the isolation valve 130 can be closed shortly before the discharge valve 145. However, it should be noted that other valve timings can be used in various embodiments of the present invention. In addition, several of the segments can be performed simultaneously (eg, a fill/distribution stage can be performed simultaneously, in which case both the inlet and outlet valves can be opened in the dispense/fill section). It should be further noted that a particular segment does not have to be repeated in each cycle. For example, the purge section and the static purge section may not be executed in each cycle. Similarly, the discharge section may not be executed in each cycle. Also, multiple dispenses can be performed prior to refilling.

Opening and closing various valves can cause pressure spikes in the fluid. Closing the purge valve 140, for example at the end of the static purge section, can result in an increase in pressure in the dispense chamber 185. This can happen because each valve can discharge a small amount of fluid when it is closed. The purge valve 140, for example, can discharge a small amount of fluid into the dispensing chamber 185 when it is closed. Because the outlet valve 147 is closed when a pressure increase occurs due to the closing of the purge valve 140, if the pressure is not reduced, a "splash" of fluid onto the wafer can occur during the subsequent dispensing section. To release this pressure during the static purge section or additional section, the dispense motor 200 can be reversed to retract the piston 192 a predetermined distance to compensate for any pressure increase caused by closing the barrier valve 135 and/or the purge valve 140. U.S. Provisional Patent Application Serial No. 60/741,681, entitled "SYSTEM AND METHOD FOR CORRECTING FOR PRESSURE VARIATIONS USING A MOTOR", filed on December 2, 2005, by the name of the s. Correction of the pressure increase caused by closing the valve (eg, purge valve 140) is described in U.S. Patent Application Serial No. 11/602,472, filed on Nov. 20, 2006, and the International Application Serial No. PCT/US06/45176. An embodiment of the invention.

The pressure spikes in the treatment fluid can also be reduced by avoiding closing the valve to create a trapped space and opening the valve between the trapped spaces. U.S. Provisional Patent Application Serial No. 60/742,168, filed on Jan. 2, 2005, which is hereby incorporated by reference in its entirety in One of the steps for timing the opening and closing of a valve to reduce the pressure spike in the treatment fluid is described in U.S. Patent Application Serial No. 11/602,465, the entire disclosure of which is incorporated herein by reference. Example.

It should be further noted that during the ready phase, the pressure in the dispensing chamber 185 may vary based on the characteristics of the diaphragm, temperature, or other factors. U.S. Provisional Patent Application Serial No. 60/741,682, filed on December 2, 2005, which is incorporated by reference in its entirety in The dispensing motor 200 can be controlled to compensate for this pressure fluctuation as described in U.S. Patent Application Serial No. 11/602,508, the disclosure of which is incorporated herein by reference. Accordingly, embodiments of the present invention provide multi-stage pumps having mild fluid handling features that can avoid or mitigate potentially damaging pressure changes. Other pump control mechanisms and valve gaskets may also be employed in embodiments of the present invention to help reduce the deleterious effects of pressure on the treatment fluid. The title of "PUMP CONTROLLER" filed on February 4, 2005 by Zagars et al., incorporated herein by reference. An additional example of a multi-stage pump 100 pump assembly can be found in U.S. Patent Application Serial No. 11/051,576, the entire disclosure of which is incorporated herein by reference.

In an embodiment, the multi-stage pump 100 incorporates a stepper motor as the feed motor 175 and incorporates the BLDCM 3030 as the dispense motor 200. Suitable motors and associated parts are available from EAD Motors of Dover, USA, or similar companies. In operation, the stator of the BLDCM 3030 produces stator flux and the rotor produces rotor flux. The interaction between the stator flux and the rotor flux defines the torque of the BLDCM 3030 and thus its speed. In one embodiment, a digital signal processor (DSP) is used to implement all field oriented control (FOC). The FOC algorithm is implemented in a computer executable software embodied in a computer readable medium. Digital signal processors, along with on-board hardware peripherals, can now be used with computing power, speed, and programmability to control the BLDCM 3030 and successfully perform FOC algorithms in microseconds at relatively low additional cost. An example of a DSP that can be used to implement embodiments of the invention disclosed herein is a 16-bit DSP (part number TMS320F2812 PGFA) available from Texas Instruments, Inc. of Dallas, TX, USA.

The BLDCM 3030 can incorporate at least one position sensor to sense the actual rotor position. In an embodiment, the position sensor can be external to the BLDCM 3030. In an embodiment, the position sensor can be internal to the BLDCM 3030. In an embodiment, the BLDCM 3030 can be sensorless. In the example shown in FIG. 1, position sensor 3040 is coupled to BLDCM 3030 for immediate feedback of the actual rotor position of BLDCM 3030, which is used by the DSP to control BLDCM 3030. An additional benefit of having position sensor 3040 is that it demonstrates extremely accurate and repeatable control of the position of the mechanical piston (eg, piston 192 of Figure 2), which means applying a pump to the piston displacement (eg, 2 is the most accurate and repeatable control of fluid movement and dispensing in the pump 180). In an embodiment, position sensor 3040 is a thin line rotary position encoder. In an embodiment, the position sensor 3040 is a 2000 line encoder. In accordance with an embodiment of the present invention, a 2000 line encoder can provide 8000 pulses or counts to the DSP. By using a 2000 line encoder, it is possible to accurately measure the rotation to 0.045 degrees and control it under a rotation of 0.045 degrees. Other suitable encoders can also be used. For example, position sensor 3040 can be a 1000 or 8000 line encoder.

The BLDCM 3030 can operate at very low speeds while still maintaining a constant speed, which means little or no vibration. In other techniques, such as stepper motors, it is not possible to operate at lower speeds without introducing vibration into the pump system, which is caused by poor constant speed control. This vibration will result in poor dispensing performance and will result in an extremely narrow operating window range. In addition, vibration can have deleterious effects on the treatment fluid. Table 1 and Figures 5 through 9 below compare a stepper motor and a BLDCM and demonstrate the many advantages of using the BLDCM 3030 as a mating motor 200 in a multi-stage pump 100.

As can be seen from Table 1, the BLDCM provides substantially increased resolution and continuous rotational motion, lower power consumption, higher torque transfer, and a wider range of speeds than stepper motors. Note that the BLDCM resolution can be more or more than about 10 times greater than the resolution provided by the stepper motor. To this end, the smallest unit of progress that can be provided by the BLDCM is referred to as "motor increment", which can be distinguished from the term "stepping", which is commonly used in connection with stepper motors. The motor increment is a minimum measurable unit that the BLDCM can provide for continuous motion while the stepper motor is moving in discrete steps, according to an embodiment.

5 is a graph comparing the average torque output and speed range of a stepper motor and a BLDCM in accordance with an embodiment of the present invention. As illustrated in Figure 5, the BLDCM maintains a nearly constant high torque output at higher speeds than the torque output of the stepper motor. In addition, the speed range of the BLDCM is wider than the speed range of the stepper motor (for example, about 1000 times or more). In contrast, stepper motors tend to have lower torque outputs that tend to degrade poorly as speed increases (i.e., torque output decreases at higher speeds).

6 is a graph comparing average motor current and load between a stepper motor and a BLDCM in accordance with an embodiment of the present invention. As illustrated in Figure 6, the BLDCM can adapt and adjust the load on the system and use only the power required to carry the load. Instead, the stepper motor uses the current set for the maximum condition, whether or not it is needed. For example, the stepper motor has a peak current of 150 milliamps (mA). The same 150 mA is used to move 1-lb. load and 10-lb. load, even if moving 1-lb. load does not require as much current as moving 10-lb. Thus, in operation, the stepper motor consumes power for maximum conditions regardless of load, resulting in inefficient and wasteful use of energy.

In the case of BLDCM, the current system is adjusted as the load increases or decreases. At any particular point in time, the BLDCM will self-compensate and supply itself with the amount of current necessary to rotate itself at the desired speed and generate the force to move the required load. When the motor is not moving, the current can be extremely low (below 10 mA). Because the controlled BLDCM is self-compensating (i.e., it can adaptively adjust the current based on the load on the system), it is always on, even when the motor is not moving. In contrast, depending on the application, the stepper motor can be turned off when the stepper motor does not move.

In order to maintain position control, the control mechanism for the BLDCM needs to be executed very frequently. In one embodiment, the control loop operates at 30 kHz for approximately 33 ms per cycle. Therefore, every 33 ms, the control loop checks to see if the BLDCM is in the correct position. If the BLDCM is in the correct position, no action is attempted. If the BLDCM is not in the correct position, it adjusts the current and attempts to force the BLDCM to the position where the BLDCM should be. This rapid self-compensating action enables extremely precise position control, which is highly desirable in certain applications. Operating the control loop at a higher speed than normal (e.g., 10 kHz) (e.g., 30 kHz) may mean additional heat generation in the system. This is because the more frequent the BLDCM switches current, the greater the chance of generating heat.

In accordance with an aspect of the present invention, in certain embodiments, the BLDCM is configured to account for heat generation. In particular, the control loop is configured to operate at two different speeds during a single cycle. During the dispensing portion of the cycle, the control loop operates at a higher speed (eg, 30 kHz). The control loop operates at a lower speed (eg, 10 kHz) during the remaining non-dosing portion of the cycle. This configuration is especially suitable for use in ultra-accurate position control system decisive applications during dispensing. As an example, the control loop operates at 30 kHz during the dispense time, which provides excellent position control. At the remaining time, the speed is switched back to 10 kH. By doing so, the temperature can be significantly lowered.

The dispensing of the loop is customized for the application. As another example, the dispensing system can implement a 20 second cycle. In a 20 second cycle, 5 seconds can be used for dispensing, while the remaining 15 seconds can be used for login or reloading, and so on. There may be a ready period of 15 to 20 seconds between cycles. Therefore, the control loop of the BLDCM will run a small percentage of the cycle (eg, 5 seconds) at a higher frequency (eg, 30 kHz) and a larger percentage (eg, 15 seconds) at a lower frequency (eg, 10 kHz) ).

As will be appreciated by those skilled in the art, such parameters (e.g., 5 seconds, 15 seconds, 30 kHz, 10 kHz, etc.) are intended to be illustrative and not limiting. The operating speed and time may be adjusted or otherwise configured to be suitable as long as it is within the scope and spirit of the invention as disclosed herein. Empirical methods can be used to determine such programmable parameters. For example, 10 kHz is a fairly typical frequency used to drive BLDCM. Although different speeds can be used, a control loop that operates the BLDCM at slower than 10 kHz can have the risk of losing position control. Since it is often difficult to obtain position control again, it is necessary to keep the BLDCM in position.

One of the aspects of this aspect of the invention aims to reduce the speed as much as possible during the non-dosing phase of the cycle without adversely damaging the position control. This goal can be achieved in the embodiments disclosed herein via a custom control mechanism for BLDCM. The custom control mechanism is configured to increase the frequency (eg, 30 kHz) to obtain some additional/increased position control for decisive functions such as dispensing. The custom control mechanism is also configured to reduce heat generation by allowing non-deterministic functions to be performed at lower frequencies (eg, 10 kHz). In addition, the custom control mechanism is configured to minimize any positional control losses caused by operation at lower frequencies during non-dosing cycles.

The custom control mechanism is configured to provide the desired dispense profile that can be characterized by pressure. This characterization can be based on the deviation of the pressure signal. For example, a flat pressure profile would imply smooth motion, less vibration, and therefore better position control. In contrast, the deviation pressure signal would imply poor position control. Figure 7 is a graph illustrating the difference between a 30 kHz motor operation and a 10 kHz motor operation (10 mL at 0.5 mL/s). The first 20 seconds is the dispensing phase. As can be seen in Figure 7, during the dispensing phase, the dispensing at 30 kHz has a lesser noise and a smoother pressure profile than the pressure profile dispensed at 10 kHz.

As for the position control of interest, the difference between running BLDCM at 10 kHz and at 15 kHz may be insignificant. However, if the speed drops below 10 kHz (eg 5 kHz), it may not be fast enough to maintain good position control. For example, one embodiment of the BLDCM is configured to dispense a fluid. When the position loop is operated at 1 ms (i.e., above about 10 kHz or above 10 kHz), no visible effects are visible to the human eye. However, when it reaches the range of 1, 2 or 3 ms, the effect in the fluid becomes visible. As another example, if the timing of the valve changes below 1 ms, any change in the result of the fluid may not be visible to the human eye. However, the variation can be visible in the range of 1, 2 or 3 ms. Thus, the custom control mechanism preferably performs time deterministic functions (eg, timing motors, valves, etc.) above about 10 kHz or 10 kHz.

Another consideration relates to internal calculations in the dispensing system. If the dispensing system is set to operate at low 1 kHz, there is no resolution that is finer than 1 ms and cannot be performed with a finer than 1 ms. In this case, 10 kHz will be the practical frequency used to dispense the system. As noted above, such numbers are intended to be illustrative. It is possible to set the speed below 10 kHz (for example, 5 kHz or even 2 kHz).

Similarly, it is possible to set the speed above 30 kHz as long as it meets the performance requirements. The exemplary dispensing system disclosed herein uses an encoder having a plurality of lines (eg, 8000 lines). The time between each line is speed. Even though the BLDCM operates quite slowly, the lines are also very thin lines, so they can appear extremely quickly, essentially pulsing to the encoder. If the BLDCM runs one revolution per second, then it means 8000 lines and therefore 8000 pulses in the second. If the width of the pulses does not change (i.e., the widths are just below the target width and remain the same repeatedly), then this is an indication of very good speed control. If the widths oscillate, depending on the system design (e.g., tolerance) and application, it is an indication of a lesser (not necessarily poor) speed control.

Another consideration involves practical limitations on the processing power of digital signal processors (DSPs). As an example, to dispense in a loop, it may take almost or just about 20 μs to perform all necessary calculations for the position controller, current controller, and the like. Operating at 30 kHz gives approximately 30 μs, which is sufficient for such calculations, with the remainder of the time being used to perform other processes in the controller. It is possible to use a more efficient processor that can run faster than 30 kHz. However, operating at a rate faster than 30 μs produces a diminishing return. For example, 50 kHz is only given for about 20 μs (1/50000 Hz = 0.00002 s = 20 μs). In this case, better speed performance can be achieved at 50 kHz, but the system has insufficient time to perform all the processes necessary to operate the controller, thus causing a processing problem. Moreover, running 50 kHz means that the current will switch more frequently, which contributes to the aforementioned heat generation problems.

In summary, to reduce heat output, a solution is to configure the BLDCM to operate at higher frequencies (eg, 30 kHz) during dispensing and to drop or cut during non-dosing operations (eg, reloading). Go back to a lower frequency (for example, 10 kHz). The factors considered in configuring the custom control mechanism and associated parameters include the speed of position control performance and calculations (which are related to the processing power of the processor) and the heat generation (which is related to the number of switching currents after calculation). In the above example, the positional efficiency loss at 10 kHz is not significant for the non-dosing operating system, the positional control at 30 kHz is excellent for the dispensing system, and the overall heat production is significantly reduced. By reducing heat generation, embodiments of the present invention can provide a technical advantage in preventing temperature changes from affecting the fluid being dispensed. This may be particularly useful in applications involving the application of sensitive and/or expensive fluids, in which case it will be highly desirable to avoid any possibility that heat or temperature changes may affect the fluid. Heating the fluid can also affect the dispensing operation. One such effect is known as the natural suckback effect. This suckback effect explains that it expands the fluid as the dispensing operation warms. As it begins to cool outside the pump, the fluid contracts and retracts from the end of the nozzle. Therefore, due to the natural suckback effect, the volume may be inaccurate and may be inconsistent.

8 is a flow chart illustrating the timing of cycling of a stepper motor and a BLDCM in various stages, in accordance with an embodiment of the present invention. Following the above example, the stepper motor implements the feed motor 175 and the BLDCM implements the dispense motor 200. The shaded area in Figure 8 indicates that the motor is in operation. In accordance with an embodiment of the present invention, the stepper motor and BLDCM can be configured in a manner that facilitates pressure control during the filtration cycle. An example of a pressure control sequence for a stepper motor and a BLDCM is provided in Figure 9, where the shaded area indicates that the motor is in operation.

8 and 9 illustrate an exemplary configuration of one of the feed motor 175 and the dispense motor 200. More specifically, once the set point is reached, the BLDCM (i.e., dispense motor 200) can begin to reverse at a programmed filtration rate. At the same time, the stepper motor (i.e., feed motor 175) changes in speed to maintain the set point of the pressure signal. This configuration offers several advantages. For example, there is no pressure spike on the fluid, the pressure on the fluid is constant, no adjustment is required for viscosity changes, no change between different systems, and no vacuum will occur on the fluid.

Although described in terms of a multi-stage pump, embodiments of the present invention may also implement a single stage pump. Figure 10 is an illustration of a pump assembly for a pump 4000. The pump 4000 can be similar to the one of the multi-stage pump 100 described above (ie, the dispensing stage) and can include a single chamber and a rolling diaphragm driven by an embodiment of a BLDCM as described herein. Pump, where the same or similar control mechanism is used for position control. The pump 4000 can include a dispensing block 4005 that defines various fluid flow paths through the pump 4000 and at least partially defines a pumping chamber. The distribution of the pump block 4005 can be an integral block of PTFE, modified PTFE or other materials. Because the materials do not react with or react minimally with many processing fluids, the use of such materials allows the flow channels and pump chambers to be directly processed into the dispensing block 4005 with a minimum amount of additional hardware. The dispensing block 4005 thus reduces the need for piping by providing an integrated fluid manifold.

The dispensing block 4005 can also include various external inlets and outlets, including, for example, an inlet 4010 for containing fluid, a purge/discharge outlet 4015 for purifying/discharging fluid, and for dispensing a fluid during the dispensing section The distribution is 4020. In the example of Figure 10, the dispensing block 4005 includes an external purge outlet 4010 because the pump has only one chamber. U.S. Provisional Patent Application No. 60/741,667, entitled "O-RING-LESS LOW PROFILE FITTING AND ASSEMBLY THEREOF", filed on December 2, 2005 by Iraj Gashgaee, incorporated herein by reference. The description of U.S. Patent Application Serial No. 11/602,513 and International Application No. PCT/US06/44981, the disclosure of which is incorporated herein by reference to the entire entire entire entire entire entire entire entire entire entire entire entire entire entire entire entire entire entire entire entire entire entire entire all An embodiment of an o-ring joint.

The dispensing block 4005 directs fluid from the inlet to the inlet valve (eg, at least partially defined by the valve plate 4030), from the inlet valve to the pump chamber, from the pump chamber to the discharge/purification The valve is directed from the pump chamber to the outlet 4020. The pump cover 4025 protects the pump motor from damage, while the piston housing 4027 provides protection to the piston and may be formed from polyethylene or other polymers. The valve plate 4030 provides a valve housing for a system that can be configured to direct fluid flow to valves of various components of the pump 4000 (eg, inlet valves and purge/discharge valves). Valve plate 4030 and corresponding valves may be formed in a manner similar to that described above in connection with valve plate 230. Each of the inlet valve and the purge/discharge valve is at least partially integrated into the valve plate 4030 and is applied to the diaphragm valve that opens or closes for the pressure or vacuum corresponding to the diaphragm. Alternatively, some of the valves may be external to the dispensing block 4005 or disposed in an additional valve plate. In the example of Figure 10, a PTFE sheet is sandwiched between valve plate 4030 and dispensing block 4005 to form a diaphragm for various valves. Valve plate 4030 includes a valve control inlet (not shown) for each valve to apply pressure or vacuum to the corresponding diaphragm.

Like the multi-stage pump 100, the pump 4000 can include several features to prevent fluid dripping into the area of the multi-stage pump 100 that houses the electronics. "Drip proof" features may include protruding lips, beveled features, seals between components, offsets at the metal/polymer interface, and other described above to isolate electronics from drops feature. The electronics and manifold can be configured similar to that described above to reduce the effects of heat on the fluid in the pump chamber.

Thus, embodiments of the systems and methods disclosed herein may utilize BLDCM to drive single or multi-stage pumps in a pumping system for performing instantaneous smooth motion and fluid movement and application in semiconductor manufacturing. Extremely accurate and repeatable position control of the dosing. The BLDCM can employ a position sensor for instant position feedback to a processor executing a custom FOC mechanism. The same or similar FOC mechanism applies to single-stage and multi-stage pumps.

The present invention has been described in detail herein with reference to the exemplary embodiments thereof Therefore, it will be apparent to those skilled in the art that the appended claims All such changes and additional embodiments are intended to be within the scope and spirit of the invention. Therefore, the scope of the invention should be determined by the following claims and their legal equivalents.

10. . . Pump system

15. . . Fluid source

20. . . Pump controller

25. . . Wafer

27. . . Computer readable medium

30. . . Control instruction

35. . . processor

40. . . Communication link

45. . . Communication link

100. . . Multi-level pump

105. . . Feeding level

110. . . Distribution level

112. . . Pressure sensor

120. . . filter

125. . . Inlet valve

130. . . Isolation valve

135. . . Barrier valve

140. . . Purification valve

145. . . Drain valve

147. . . Outlet valve

150. . . Feed level pump

155. . . Feed into the chamber

160. . . Feed-in diaphragm

165. . . piston

170. . . Lead screw

175. . . Feed motor

180. . . Distribution level pump

185. . . Dispensing chamber

190. . . Application level diaphragm

192. . . piston

195. . . Lead screw

200. . . Distribution motor

3000. . . Motor assembly

3010. . . Diaphragm assembly

3020. . . Lead screw

3030. . . motor

3040. . . Position sensor

4000. . . Pump

4005. . . Distribution block

4010. . . Entrance

4015. . . Purification/discharge exit

4020. . . Distribution exit

4025. . . Bang cover

4027. . . Piston housing

4030. . . Valve plate

1 is a diagram of a motor assembly having a brushless DC motor in accordance with an embodiment of the present invention; and FIG. 2 is a diagram of a multi-stage pump implementing a brushless DC motor in accordance with an embodiment of the present invention; 3 is a diagram of a pumping system for implementing a multi-stage pump according to an embodiment of the present invention; FIG. 4 is a diagram showing the timing of valves and motors used in an embodiment of the present invention; FIG. 5 is a diagram of a valve and a motor according to an embodiment of the present invention; An embodiment compares a graph of average torque output and speed range of a brushless DC motor and a stepper motor; FIG. 6 is a graph comparing average motor current between a brushless DC motor and a stepper motor according to an embodiment of the present invention; Figure 7 is a graph showing the difference between a 30 kHz motor operation and a 10 kHz motor operation; Figure 8 is a diagram illustrating a brushless DC motor and a stepper motor in various stages in accordance with an embodiment of the present invention. FIG. 9 is a flow chart illustrating pressure control timings of a stepping motor and a brushless DC motor at the beginning of a filtering process according to an embodiment of the present invention; and FIG. 10 is a flowchart according to an embodiment of the present invention. An illustration of a single-stage pump that implements a brushless DC motor.

Claims (13)

A pump system comprising: a pump; a brushless DC motor driving a dispensing pump residing in the pump, wherein the dispensing pump includes an inlet and an outlet; a computer readable medium a processor that carries the software instructions for controlling the pump; and a processor communicatively coupled to the computer readable medium and the pump, wherein the software instructions are executable by the processor to perform Controlling the brushless DC motor for operating a control mechanism that dispenses the pilot pilot fluid from the inlet to the outlet; wherein the control mechanism is configured to operate the brushless DC at a first frequency during dispensing The motor and operating the brushless DC motor at a second frequency below the first frequency during a non-dosing operation. The pumping system of claim 1, wherein the dispensing pump is a piston displacement pump, the piston displacement pump comprising: a dispensing chamber; a piston; and a dispensing diaphragm positioned at the dispensing Between the chamber and the piston; and a lead screw connecting the piston to the brushless DC motor. The pumping system of claim 2, further comprising a position sensor coupled to the brushless DC motor and in communication with the processor for providing immediate position feedback of the piston. The pumping system of claim 3, wherein the position sensor is internal or Externally coupled to the brushless DC motor. The pumping system of claim 3, wherein the position sensor is operative to provide immediate feedback of the position of the brushless DC motor to the processor such that the processor can control the piston to rotate at 0.045 degrees. The pumping system of claim 3, wherein the position sensor is a 1000 line encoder, a 2000 line encoder or an 8000 line encoder. The pumping system of claim 1, wherein the control mechanism is configured to minimize heat generation of the brushless DC motor during operation of the dispensing pump. The pumping system of claim 1, wherein the control mechanism is configured to provide a desired dispensing profile characterized by the smoothing of a pressure signal. For example, the pump system of claim 1, wherein the pump is a single-stage pump or a multi-level pump. A pump comprising: a dispensing pump, wherein the dispensing pump is a piston displacement pump, the piston displacement pump comprising: an inlet; an outlet; a dispensing chamber; a piston; Disposing a stage diaphragm positioned between the dispensing chamber and the piston; a brushless DC motor; and a lead screw connecting the piston and the brushless DC motor; wherein the brushless DC motor is embodied in On a computer readable medium and by an implementation for operating the dispensing pump to direct fluid from the inlet to the Controlled by a software instruction executed by a processor of the control mechanism of the outlet, and wherein the processor is communicatively coupled to the computer readable medium and the pump; wherein the control mechanism is configured to be first during the dispensing period The brushless DC motor is operated at a frequency and the brushless DC motor is operated at a second frequency below the first frequency during a non-dosing operation. The pump of claim 10, further comprising a position sensor coupled to the brushless DC motor and in communication with the processor for providing instant position feedback of the piston. The pump of claim 11, wherein the position sensor is internally or externally coupled to the brushless DC motor. The pump of claim 11, wherein the position sensor is operative to provide immediate feedback of the position of the brushless DC motor to the processor such that the processor can control the piston to rotate at 0.045 degrees.