KR20090107448A - Helium management control system - Google Patents

Abstract

PURPOSE: A helium management control system is provided to detect and re-distribute excessiveness and extra helium refrigerant in each cryogenic pump by monitoring various parameters through a sensor. CONSTITUTION: A helium management control system includes a compressor storage(16) and a plurality of cryogenic pumps. The compressor storage has more than one compressor(16a-16n). In a cryogenic cooling system, a refrigerant is supplied from the supply line connected to the compressor storage. A method of system control is comprised of the steps: determining an operation parameter in considering the pressure difference between a feed line connected with the cooling system and the supply line; allotting a refrigerant to the cooling system based on the operation parameter; and re-allotting a refrigerant to the cooling system based on the operation parameter including a change of pressure difference.

Description

Helium Management Control System {HELIUM MANAGEMENT CONTROL SYSTEM}

 The present invention relates to a system control method comprising a plurality of cryogenic chillers.

Vacuum processing vessels are frequently applied in manufacturing to provide a vacuum environment for operations such as semiconductor wafer fabrication, electron microscopy, gas chromatography, and the like. Typically such vessels are manufactured by attaching a vacuum pump to a vacuum processing vessel in a closed apparatus. The vacuum pump is operated to sufficiently remove all molecules from the vacuum processing vessel, resulting in a vacuum environment.

One form of vacuum pump is a cryogenic pump, which is published in US Pat. No. 5,862,671 (registered January 26, 1999), assigned to the assignee of the present application and incorporated herein by reference in its entirety. The cryogenic pump cools the surface to remove molecules from the vacuum vessel by reaching absolute zero. At this temperature, most of all the gas condenses on a cooled surface called a cryogenic array, thereby removing substantially all molecules from the vacuum processing vessel.

Cryogenic pumps use helium-driven chillers to reach the required absolute zero. The compressor compresses the helium coolant and pumps it to the chiller by a cryogenic pump, and a cylindrical vessel called a cooling finger in the cryogenic chiller receives the helium. The cryogenic array is attached to, and in thermal communication with, a cooling finger and cooled with it. The filter reciprocates inside the cooling finger as helium expands, and is driven by a filter drive motor, which filters the filter and drives the amount of helium used. As helium expands in the cooling finger, it takes heat away from the cryogenic array, producing a temperature close to zero that is necessary for condensing the gas in the cryogenic array.

The amount of helium coolant available for the cryogenic chiller determines the rate at which it cools. As the supply of helium increases, the time required for cooling decreases, which is the time required to reach the cryogenic pumping temperature. In addition, the helium consumption rate varies with the temperature of the cryogenic chiller. As the cryogenic chiller cools, the supply of helium needs to be increased to continue the cooling process. In cryogenic pumped vacuum processing vessels, downtime is a substantial economic drawback as it reduces manufacturing time. Thus, the ability to quickly reach and maintain cryogenic pumping temperatures is useful.

One type of prior art relating to helium distribution is described in US Pat. No. 5,775,109 (filed Jan. 2, 1997) entitled "Enhanced Cooling of Complex Cryogenic Chillers Supplied by Common Compressors", the assignee of the present invention Is incorporated by reference in its entirety. The patent proposes to individually monitor the temperature of each of the cryogenic pumps in order to adjust the speed of each strainer drive motor when the cryogenic pump reaches the triggering temperature. Since cryogenic pumps require varying amounts of helium depending on the operation currently being performed, the drive motor speed can be adjusted to appropriately reduce or increase the helium supply. In such a system, each cryogenic pump monitors the temperature and adjusts the drive motor speed accordingly.

However, a common helium feed branch that supplies multiple cryogenic pumps can often supply more helium than required by both cryogenic pumps. Unidentified excess helium is not often utilized, increasing the time required for cooling, which causes the cryogenic chiller to cool more than is needed and waste other sources needed to maintain power and helium chiller supplies.

summary

A method of adjusting the distribution of a source of coolant, such as a coolant, between a plurality of consumers, such as a chiller, is provided by calculating the available amount of coolant and calculating the required amount of coolant by each of the plurality of coolers. The requirements of the equipment used are summed and the allocation of coolant based on the combined requirements is determined for each of the chillers. Periodically, at regular intervals, the allocation of coolant is re-evaluated by re-evaluating each user's needs by re-evaluating the current needs for each of the chillers.

In systems such as cryogenic cooling systems, the control method includes a compressor reservoir having one or more compressors and a plurality of cryogenic chillers that receive coolant from the compressor reservoir. The management of the coolant supply from the compressor to each of the cryogenic chillers is performed by determining the degree of cooling demand of each of the chillers and allocating the supply of coolant to the chiller according to the demand determined from the vacuum network controller.

An embodiment of a helium management control system for regulating the helium coolant supply from a common branch pipe provides an adequate amount of helium supply to a number of cryogenic chillers. The system uses a number of sensors that monitor and regulate the total coolant supply to perform a coolant supply to each of the cryogenic chillers according to the total cooling load of all cryogenic chillers. The coolant demand for each cryogenic chiller is calculated by the corresponding cryogenic pump. The total cooling capacity of the helium supply is assigned to each cryogenic chiller to optimize coolant delivery. The proper supply of helium is distributed to each cryogenic pump by detecting excess and lack of helium coolant and distributing the coolant accordingly. If the total coolant supply exceeds the total coolant requirement, the excess coolant is transferred to the cryogenic chiller so that the cryogenic chiller uses excess helium. Similarly, if the total cooling demand exceeds the total cooling supply, then the coolant supply to some or all of the cryogenic chillers is appropriately minimized to minimize the adverse or slowing effect.

The coolant supply consists of a plurality of cryogenic chillers from one or more compressors or common compressor reservoirs through a helium feed branch. The coolant supply from each compressor including a common compressor reservoir is used to determine the coolant supply. In addition, the total coolant demand calculated based on the data from the sensors attached to each of the cryogenic pumps including the cryogenic chiller, is calculated according to the specific operation performed by the cryogenic chiller. The coolant supply is calculated for each cryogenic chiller because one job consumes more coolant than the other. The cooling function requires the most helium and thus can be provided with the maximum coolant supply that is transported without dispensing to other cryogenic chillers. The regeneration function requires little or no coolant, thus releasing the coolant for other cryogenic chillers. During normal operation of one or more cryogenic chillers, helium is moved to keep the cryogenic chillers in equilibrium. Excess helium is transferred to a chilled cryogenic chiller or the total coolant supply is reduced if there is no need for excess helium.

The system monitors various parameters to calculate the appropriate coolant supply for each cryogenic chiller. The parameters include the calculated coolant flow rate through the cryogenic chiller, the speed of the drive motor, the pressure of the coolant, and the temperature of the cryogenic chiller. In this way, depending on the total coolant load and the current cooling function of the individual cryogenic chillers, an appropriate coolant supply can be delivered from the common compressor reservoir to the multiple cryogenic chillers. Thus, the helium management control system minimizes the disadvantages or slowing effects resulting from the lack of coolant supply and increases performance when the coolant supply is excessive.

Preferred embodiments of the present invention are as follows.

Before discussing helium management control, it is beneficial to discuss the cryogenic pump (pump) operation. Vacuum pumps, such as cryogenic pumps and water pumps, are used to bring the vacuum processing vessel to about zero atmospheres. About 0 atm, or less, on the order of 10 ^-6 to 10 ^-9 Torr is achieved by substantially removing all molecules from the vacuum processing vessel. Molecules are removed from the vacuum processing vessel through the cryogenic chiller of the cryogenic pump. A portion of the cryogenic chiller is cooled to about absolute zero, typically 10-20 K, which condenses all the molecules of the treatment vessel into the cryogenic array cooled by the cryogenic chiller. Cryogenic arrays are generally a set of louvers and baffles that provide surface area for dense volumes. Thus, the condensed gas turns into a solid state with low vapor pressure and becomes almost vacuum. Cryogenic arrays also include absorbing materials such as charcoal, which absorb molecules that do not condense, such as hydrogen, helium, and neon. Cryogenic chillers are powered by a cooling working fluid, such as helium gas, which can reach temperatures close to zero absolute.

Cryogenic pumps consume varying amounts of helium depending on their current operation and temperature. A series of pumps are connected to the common compressor reservoir of one or more compressors to maximize the valid helium supply. Helium consumption by the pump is monitored and regulated by the controller. By monitoring the various operating parameters of each pump, an adequate supply of helium is supplied to each pump. Excess helium is moved back to be used for the pump using it. Lack of helium is limited in supply to maintain operation and to minimize harmful effects.

In a typical cryogenic pump chiller, the working fluid is compressed; Heat in the compressor is removed by an air-cooled heat exchanger; The fluid is again cooled in the regenerative heat exchange substrate; The gas is then expanded and cooled to below ambient temperature. Cryogenic pumps must be operated effectively at less than 20K to remove gas molecules from the vacuum vessel. To reach the low temperature, a very efficient heat exchanger and a working fluid such as helium gas, which remains gaseous at temperatures approaching absolute zero, must be used.

In the cryogenic chiller of the pump, the flow of compressed gas coolant is circulating. In the most basic form of cryogenic chillers, a source of compressed gas, for example a compressor, is connected to the first end of the cylinder via an inlet valve. The discharge valve of the discharge line is connected from the first end to the low pressure inlet of the compressor. The filter includes a chiller located at the second, cooling end of the cylinder, the cylinder being filled with compressed gas when the discharge valve is closed and the inlet valve is opened. When the inlet valve is open, the filter moves to the first end and moves the compressed gas to the second end through the chiller, where the gas is cooled while passing through the chiller. When the inlet valve is closed and the outlet valve is opened, the gas is expanded to a low pressure outlet line for further cooling. The temperature gradient of the cylinder wall at the second end thereby causes heat to flow from the rod to the gas in the cylinder. When the discharge valve is opened and the inlet valve is closed, the filter moves to the second end and exchanges the gas again through a cooler that returns heat to the coolant gas, thereby cooling the cooler and the circulation is completed. In a typical pump, the cylinder is called a cooling finger and includes a first step and a second step.

In order to produce the low temperatures required for cryogenic pump operation, the incoming gas must be cooled before expansion. The cooler obtains heat from the incoming gas, stores it, and releases it to the exhaust stream. The regenerator is a reverse-flow heat exchanger through which helium selectively moves in either direction. Refrigerant coolers include materials of high surface area, high specific heat and low thermal conductivity. As such, the cooler will receive heat from helium when the temperature of helium is higher. If the temperature of helium is lower, the cooler will release heat to helium.

1A shows a block diagram of a cryogenic chiller 10. In the apparatus of FIG. 1A, helium enters the cooling fingers of the chiller through high pressure valve 46 and out through low pressure valve 48. The filter drive motor 216 drives the filters 207 and 209 in the first and second stages of the cryogenic chiller, respectively. The first stage filter 207 includes a first cold storage 211, and the second stage filter 209 includes a second cold storage 213. Heat is obtained from the first stage heat rod 203, eg, cryogenic pump radiation shielding and frontal array, and the second stage rod 205, eg, 10K-20K cryogenic panel.

1B shows a cross-sectional view of a cryogenic pump that includes a cryogenic chiller. In FIG. 1B, the pump housing is removed to expose the strainer drive 40 and the crosshead assembly 42. The cloth head converts the rotational movement of the motor 40 into a reciprocating motion that drives the filter in the two-stage cooling finger 44. Within each circulation, helium gas, which is introduced into the cooling finger under pressure through line 46, expands and thus cools to keep the cooling finger at cryogenic temperatures. The helium warmed by the heat exchange substrate in the filter is then discharged through line 48.

The first stage heat station 50 is mounted to the cooling end of the first stage 52 of the chiller. Similarly, heat station 54 is mounted to the cooling end of second step 56. Suitable temperature sensor components 58 and 60 are mounted to the back of the heat stations 50 and 54.

The first pumping surface is cryogenic array 62 mounted to heat sink 54. The array includes a number of disks disclosed in US Pat. No. 4,555,907, which is incorporated herein by reference in its entirety. The cold absorbent is mounted to the protected surface of the array 62 to absorb gases that cannot be compressed.

The cup-shaped radiation shield 64 is mounted to the first stage heat station 50. The second stage of the cooling finger extends through the opening of the radiation shield. The radiation shield 64 surrounds the first cryogenic panel array on the back and side surfaces to minimize heat generation of the first cryogenic panel array by radiation. The temperature of the radiation shielding is in the range of high temperature, such as 130K, adjacent to the opening 68 of the vessel discharged from a low temperature, such as 40K of the heat sink 50.

The front cryogenic panel array 70 serves as a cryogenic pumping surface for high boiling point gases such as water vapor and radiation shielding for the first cryogenic panel array. The panel comprises a circular array of symmetrical louvers and chevrons 72 joined by spoke-shaped plates 74. The shape of the cryogenic panel 70 need not be limited to circular, centrally shaped components; It is arranged to function as a radiant heat shield and a high temperature cryogenic pumping panel to provide a passage for low boiling gas to the first cryogenic panel.

2 shows a reservoir of a compressor used to supply helium coolant to a series of pumps. 2, the common compressor reservoir 16 includes compressors 16a to 16n for supplying helium coolant to the branch pipe 18. Branch pipe 18 is coupled to slave engine controllers 215a through 215n and connected to a series of pumps 10a through 10n. The slave engine controllers each control the strainer drive motor 216, which drives the strainer reciprocating at the cooling finger as the helium gas expands. The filter drive motor is used to regulate the cooling rate of the pump by the amount of helium supplied. The vacuum network main unit controller 12 (controller) or VNC is connected to each of the slave unit controllers controlling the filter drive motor 216 and is used to increase or decrease the amount of helium coolant supplied to the pump 10. . Each of the pumps 10 has one or more sensors 14a-14n, which provide feedback to the controller 12. Accordingly, the controller 12 receives each signal 10 based on the signal received from the sensor 14 and the total amount of helium effective from the branch pipe as received from the sensor 14 as described in more detail below. Calculate the amount of helium for adjusting all the pump (10) connected thereto.

It should be noted that the helium management control system is described in combination with the cryogenic chiller typical of cryogenic pumps. Helium management control systems can be used in connection with the supply of helium to drive various cryogenic chillers. The cryogenic pumps described herein are, for example, water pumps cooled by one stage cryogenic chillers, and are disclosed in US Pat. No. 5,887,438, entitled "Thin Line Cryogenic Water Pumps," which is incorporated by reference in its entirety. As a helium-driven cryogenic device.

Depending on the cooling operation of the pump, the rate of helium consumption varies. Cooling operation brings the temperature of the pump from cryogenic to cryogenic and requires most of helium. If cryogenicity is achieved, the normal operating mode maintains the temperature and requires a generally stable flow of helium. Regenerative operation warms up the pump to release accumulated and condensed gas and requires little or no helium. Other factors can affect the rate of helium consumption. During the cooling period, the pump consumes more helium gradually to reach normal operating temperature as it cools. At normal operating temperatures, the vacuuming activity occurring in the attached vacuuming vessel generates heat, increasing the cooling load, which increases the rate of helium consumption.

The total helium transport rate of all pumps connected to the common coolant supply is used to determine the total cooling demand. Similarly, the coolant capacity of the compressor or compressors that contribute to the common coolant supply is used to determine the coolant capacity of the system. As pointed out above, the actual consumption rate of each pump varies with various factors. In certain cases, the coolant capacity of the system exceeds the total cooling load, which means that there is excess helium in the system. Similarly, if many pumps go through a high helium consumption period, the total cooling load exceeds the cooling capacity, which means helium deficiency.

By monitoring the current operation and total coolant capacity of all pumps, excess helium is identified and converted to a pump that can use it. Similarly, insufficient helium is properly allocated to maintain normal operation, or mitigates harmful effects in extreme situations. For example, the cooling operation consumes the most helium and thus reduces the time required for cooling by converting excess helium into the pump being cooled. Pumps in regenerative operation require little or no helium, so excess helium is present. In addition, the pump in normal operation starts to rise in temperature. To maintain the cryogenic pumping temperature, helium is switched from the pump being cooled to increase the cooling time but to preserve the cryogenic pumping temperature in the pump that has started to warm up for continued normal operation.

3 shows an example of the helium distribution flow rate over time. Each of the four pumps 301-304 is shown according to the time shown by the horizontal axis. Initially all pumps consume equally. At the time shown by dashed line 310, pump 303 enters a regeneration state and is warmed. Thus, additional helium is provided to the pumps 301, 302, and 304. Optionally, if the increased helium is inefficient, the drive motor speeds of the pumps 301, 302, and 304 are reduced to reduce the collection of all helium from the common compressor reservoir. At the time shown by dashed line 312, pump 303 completes regenerative warming and enters a cooling state. Thus, excess helium is diverted from pumps 301, 302, and 304 to accelerate cooling of pump 303. At the time shown by dashed line 314, cryogenic pump 303 completes cooling and all pumps return to the same rate of consumption at the time shown by dashed line 316.

In general, helium consumed by cryogenic pumps is expressed in units of mass flow rate, for example, three cubic feet per minute (SCFM) at a specific temperature and pressure. In addition, other units, such as grams per second, are used to represent mass flow rates. The helium consumed is determined from the maximum and minimum helium mass present in the cooling finger when the filter reciprocates in the circulation mode. 4 shows the filter position for the maximum and minimum helium mass in the cooling finger when calculating the helium consumption rate for the cryogenic chiller of the cryogenic pump. The filters having the first and second stages 207 and 209 reciprocate through the interior of the cooling finger 44, respectively. As the filter reciprocates by the drive motor 215, helium expands to cool the cooling fingers. In addition, each exchanger cycle opens high pressure 46 (feed) and low pressure 48 (exhaust) lines to collect unexpanded helium and consumes expanded helium. The amount of helium consumed is given by the formula:

Flow rate = (maximum flow rate-minimum flow rate) * drive motor speed

Thus, as the speed of the drive motor increases, the helium consumed increases due to increased exchanger circulation, thereby collecting additional heat from the load.

For example, if a common compressor reservoir moves helium 84 SCFM, the compressor reservoir supplies helium 14 SCFM to six chillers: 84/6 = 14. As pointed out above, the helium consumed by the pump varies. If four chillers consume only helium 12.5 SCFM, the chiller load from the four chillers is 12.5 * 4, i.e. 50 SCFM. Since the compressor supplies 84 SCFM, the remaining two chillers are 84-50, or 34 SCFM. If the remaining two chillers are in a cooled state, they are each supplied with 34/2, or helium 17 SCFM, due to the excess in the system. In alternative embodiments, excess helium need not be allocated to the cooled chiller in the same amount.

5 shows a block diagram of a data flow of an embodiment of a helium management control system. With respect to FIG. 5, each of the compressors in the common compressor reservoir 16 sends an indication of the maximum helium available from each compressor to the controller 12, which allows calculation of the total helium supply. Each of the pumps 10 sends the following parameters to the controller: helium consumption state indicating the minimum amount of helium, the currently calculated rate of helium consumption, the mode of operation and the helium deficiency. The controller 12 sends the assigned helium parameter or value to the pump indicating the maximum helium speed that the pump can consume. The maximum helium consumption signal is used to regulate the exchanger drive motor through slave controller 215 connected to a particular cryogenic chiller. As pointed out above, the speed of the filter drive motor regulates the helium consumption of the pump.

6 shows a top flow diagram of the control flow of the helium management control system. The system polls at regular intervals to determine if the helium supply to any cryogenic pump needs to be adjusted. Optionally, the system is interrupt or event driven. When the polling interval ends, as shown in step 100, it is checked that all cryogenic pumps are operating normally as described in step 102. If all pumps are operating normally, as described in step 104, the system waits for the next polling interval. If any pump or system is not operating normally, i.e. if one or more pumps have reached the limit of permitted consumption, or if the system differential pressure DP has been reduced below the threshold, step 106 As shown, helium management control is performed, which is further described below. Two embodiments of helium management control are described below.

7 shows a block diagram of the data flow between the vacuum network controller (VNC 12) or main unit controller, compressor 16 and slave unit controllers 215a-215d of the pumps 10a-10b. The compressor sends a supply pressure and a return pressure to the VNC 12. In addition, the compressor delivers an initial value of helium that is fed at standard square feet (SCFM) per minute. The underpressure checking routine 110 of the VNC, described further below with respect to FIG. 10, calculates an effective helium correction value 112. The effective helium correction value is periodically recomputed to approximate the amount of helium available for allocation based on the current consumption. This value varies somewhat around the rated feed value based on compressor displacement and speed due to factors such as the consumption and splitting and efficiency of pump 10 and compressor 16. The effective helium modification 112 value is used in the distribution routine 114 and is further described below with respect to FIG.

The calculated and assigned helium value is sent to slave device controllers 215a-215d that control each pump 10a-10d as shown by arrow 116. The slave device controller determines the maximum filter motor speed at which the filter motor runs without exceeding the assigned helium value. In addition, the pump speed control loop of the slave unit controller controls the exchanger motor speed and runs the motor at low speed under the action of the cryogenic pump temperature, but does not exceed the speed corresponding to the assigned helium value. The pump speed control loop also allows the pump to freely consume helium up to its default assigned value in a standalone mode that is not driven by the VNC 12 depending on the temperature. Subsequent device controller 215 then calculates a helium consumption value that represents the actual helium consumption, as described further below. Like the total effective helium value, the helium consumption value differs from the rated displacement value for the pump depending on current operating conditions and factors such as consumption and splitting. The helium consumption value is sent back to the VNC 12 for continuous helium allocation value calculation, as shown by arrow 118.

8 is a state diagram of the VNC 12. 6, 7 and 8, state transitions occur with the operation of the system at each polling interval 100. The idle state 120 occurs at the preparation and mapping of the system and performs initial writing and default values before starting the pump 10 and compressor 16. In addition, an initial size check is performed to confirm that the compressor is properly fitted to the pump 10 connected to the branch pipe. When one or more pumps 10 and one compressor 16 are started, the VNC 12 transitions to the monitor state 122.

In the monitor state 122, the pump 10 is polled by the VNC at each polling interval 100 to determine if any pump 10 is operating in the limit state, which is further described below. The pump 10 operating in the critical state consumes at or near its maximum allowable consumption and needs more helium to avoid warming up. The transition to the dispense state 124 for the request occurs when one or more pumps 10 report a threshold condition or when the DP falls below the threshold. The distribution 124 on demand is to reallocate excess helium in the system to provide more helium to the pump 10 at the limit, which is further described in FIG. 9 below. If the distribution 124 for the request is not able to reallocate enough helium for the pump 10 to leave the DP still out of the lower limit, the system will either be overloaded or distribution 128 to the hierarchy. Is switched to.

In the overload condition 126, the VNC 12 maintains a current allocation for each pump because as much helium has already been reallocated as possible to the pump consuming excessively. For example, if five out of six pumps are working properly, but the sixth pump consumes excessively due to a defective auxiliary valve, allocating more helium to the defective pump will only take away from the other five pumps. will be. The distribution state 128 for the tier, on the other hand, attempts a more aggressive approach and optionally blocks the pump 10 according to the user-specified tier. For example, when the pump is cooled, it is beneficial to terminate the cooling operation and switch to downtime to save payload to avoid compromising other pumps currently active with wafer payload. However, because the distribution to the hierarchy causes VNC to actually terminate the operation, the user does not want this feature to be allowed.

9 is a flow diagram of the operations performed in the distribution state 124 for requests. With respect to FIG. 9, as shown in step 130, a distribution state for the request begins. Each of pump 10 and compressor 16 is polled to determine current operating parameters, as shown in step 132. Supply pressure and return pressure are accommodated and the same for all compressors connected to a common branch. The pump operating parameters are the currently calculated helium consumption value, current helium allocation value, consumption state (position), OK or limit, current cooling mode, "on" (cooler running, temperature control on or temperature control auxiliary). Manual operation), "cooldown" (cooler running to achieve the target temperature), or "off" (cooler running, do not consume helium), and the pump is required to operate Contains a minimum of helium. The cooling mode refers to the current cooling operation performed by the pump, which means "cooling while cooling," temperature control when the pump is being controlled by the VNC, and "none" when helium is not needed, such as regeneration operation. "Is specified.

As described in step 134, it is checked whether the stabilization period has ended since the last redistribution. The stabilization timer refers to the time taken to determine whether full redistribution is valid and is typically one minute. If the stabilization timer is not terminated, control returns to step 130 to wait for the next polling interval. If the stabilization timer is terminated or if no stabilization timer is specified, then it is checked whether an overload or distribution to layer (DPH) state should be started as described in step 136. If an underpressure condition exists, the system continues to consume excessively and all the cooling pumps are running at the minimum helium dispense value, an overload or DPH is started. If the DP obtained in step 132 is less than a certain target threshold, underpressure conditions exist when it is generally less than 190 lbs / in ² . As described above, a typical operational DP is about 200 lbs / in ² , which corresponds to 400 and 200 lbs / in ² , respectively, for supply and return pressures.

The system consumes excessively when the sum of the helium consumptions calculated from all pumps is greater than the current or most recently calculated modified effective helium 112 (FIG. 7) value. In certain embodiments, the pump consumes excessively when the calculated sum of helium consumption exceeds 5% of the modified effective helium 112.

The third condition is that all pumps reporting the cooling mode are already at the minimum helium allocation as reported in step 132. The system attempts to lower the assigned helium parameter for the cooling pump to allow more helium for the pump under temperature until the minimum helium quota is reached. If all pumps reach the minimum helium quota, there will be no excess helium to allocate to other pumps.

If the pumps being cooled are all in the minimum helium state and the underpressure and overconsumption tests are positive, then as shown in step 138, it is checked whether the DPH is started and allowed. If DPH is started and allowed, it enters the DPH state 128 and otherwise enters the overload state 126.

If the system does not yet need to be switched to overload 126 or DPH 128, the pressure insufficient test routine 140 begins to calculate a new value for the modified effective helium, which is described below with reference to FIG. Is described. Next, a dispensing routine, further described below, begins as described in step 142. The dispensing routine also recalculates the new assigned helium value for each of the pumps 10. The system checks whether redistribute helium is sufficient to allow the state to transition to the monitor 122, as shown in step 144. If the stabilization timer has elapsed and the pump does not report a threshold condition, the VCN transitions to monitor state 122 because none of the pumps has been deprived of sufficient helium. Next, as described in step 146, it is checked whether all compressors or all pumps are closed. If none of the compressors or pumps are turned on, the system transitions to idle state 120. Finally, as described in step 148, the newly calculated value for helium allocation is sent to the pump 10.

10 shows in more detail the underpressure inspection routine of step 140. With reference to FIG. 10, underpressure inspection routine 140 begins as shown in step 150. Check that the system is operated at underpressure as described in step 152. The check may include reading the flag set in step 136 above, or it may recompute the DP and compare it with the DP target value. If the system is still operating under underpressure, the flow correction factor is reduced by a predetermined value, for example 0.01, as described in step 154. Next, as shown in step 158, the flow correction factor is multiplied by the modified current effective helium value 112 to evaluate the new modified effective helium value 112, as shown in step 162. Control switches to the distribution flow chart for the request. In this way, the computed effective helium is reduced to allow a dispensing routine, as described further below, and calculates the helium allocation from fewer supplies. Thus, successive iterations have the effect of lowering the calculated effective helium until the system is stable or switched to overload 126 or DPH 128.

If there is no underpressure condition, as shown in step 156, the total calculated helium consumption for all pumps is above or below any threshold of the modified effective helium value 112. Check it. As shown in step 160, if the total calculated helium consumption is within any threshold, the helium flow is sufficient, the flow modification factor is increased to a predetermined value, for example 0.01, and the calculated effective helium To increase. Next, the corrected valid helium value is recalculated as shown in step 158 and control returns to the DPD routine as described in step 162.

11 shows in more detail the dispensing routine of step 142 (FIG. 9). With regard to FIG. 11, a dispensing routine begins as shown in step 164. The new assigned helium value for the pump in the temperature control mode is calculated as shown in step 166. The calculated helium consumption value reported by each pump is multiplied by the delta helium factor of step 156 to provide more helium to the pump under temperature control. In certain embodiments, the delta helium factor is 1.08. Next, as shown in step 168, helium is computed that is valid for allocation to the pump upon cooling during cooling. The helium consumption values calculated in step 166 are summed for all pumps under temperature control and subtracted from the current value of the modified effective helium to evaluate the helium available for cooling. Therefore, all pumps under temperature control are considered first and the remainder is allocated between the pumps being cooled. As described in step 170, the helium available for cooling is divided by the number of pumps being cooled, and weighted to match the relative size of the pumps if they are currently attached to the branch with different sizes. Also, if the calculated helium quota is less than the minimum helium quota for a particular pump, the minimum helium quota is used. Thus, the system seeks to redistribute additional helium to the pump in temperature control to mitigate the threshold condition of one or more pumps reporting the condition. Control then passes to a dispensing routine, as shown in step 172.

12 shows a top diagram of a pump control flow. As noted above, the pump is operated in one of three modes: temperature control, cooling and non, and two states: OK and limit. The pump also calculates the helium consumption value to report to the VNC. The pump slave device controller periodically sends this information when required by the VNC and receives an assigned helium value from the VNC. The pump speed control loop flow then adjusts the maximum filter speeds (RPMs) accordingly. The pump speed regulation loop is activated and simultaneously adjusts the filter motor speed according to the first state temperature within the RPM range calculated by the pump control flow. In certain embodiments, the pump speed control loop is a closed loop proportional-integral-differential (PID) loop.

With reference to FIG. 12, as shown in step 174, the pump control flow loop of the pump slave device controller is started. The start is started by the VNC 12, but also from asynchronous means such as an interrupt drive mechanism. As described in step 176, it is checked whether the present values of the compressor supply and return pressure used to calculate DP are valid. Causes of invalid compressor values include communication failures between the pump, compressor, and VNC, transducer failure, or the compressor turning off. As described in step 178, if the compressor value indicates a possible problem, the compressor check routine is initiated and is further described below. If the compressor value is valid, it is checked whether the pump is closed by the compressor check routine as described in step 180. If the pump was previously closed by the compressor check routine, power failure recovery is performed and initialized, as shown in step 182, and exits the pump control loop, as shown in step 194. If the pump has not been previously closed, the current operating parameters are calculated for the pump as described in step 184.

The operating parameters are calculated as follows: Pump constant (Cpumpconst) based on the first stage temperature, the second stage temperature, the current controller speed (RPM), the supply pressure, the return pressure, and the exchange of the pump by calculating the helium consumption parameter. Determine the current helium consumption rate based on

Helium consumption = F (T1, T2, RPM, P _feed , P _regression , C _{pump constant} ).

The new assigned RPM value corresponding to the helium consumption value is calculated using the current allocated helium value received from VNC:

RPM assigned = (assigned helium * RPM) / helium consumption.

It should be noted that the helium consumption value is also sent back to the VNC as described above to compute a new value for the assigned helium value. The pump status of OK or limit, and the pump operating mode, the temperature control and the non-cooling are also calculated and sent to the VNC.

After calculating the pump operating parameters, it is checked whether the pump is in cooling mode, as shown in step 186. If the pump is in the cooling mode, the cooling routine begins as shown in step 188, which is further described below. If the pump is not in cooling mode, as described in step 190, it must be turned on or off (for temperature control) and the maximum RPM is the smaller of the assigned RPM, the maximum RPM for this pump, or the total maximum RPM constant. , Typically set at 100 rpm and above the minimum RPM, exit the pump control loop as shown in step 194.

13 shows a pump cooling routine. 12 and 13, when the pump is in the cooling mode, control passes to the cooling routine, as shown in step 188. As shown in step 400, a cooling routine is started to check whether the second stage temperature is less than 17K. If the temperature is less than 17K, it is checked whether the first stage temperature is within 0.5K, which is the T1 target value, generally 100K. T1 (step 1) is assigned to the target normal operating temperature. If T1 (first step) is sufficiently cooled, cooling is complete as described in step 406 and exits the cooling routine as shown in step 422.

If the second stage temperature is more than 17K, it is checked whether the second stage temperature is less than 40K. If the second step is less than or equal to 40, or if the first step is greater than or equal to 0.5K within the target value of step 404, then it is checked whether the allocated RPM exceeds 72 rpm as shown in step 408. If the allocation RPM exceeds 72, set it to 72 rpm as shown in step 410. Therefore, if the second stage is less than 40K or the second stage is less than 17K, the allocation RPM is limited to 72, but the first stage should not drop to the T1 target value + 0.5K.

It is checked whether the calculated RPM calculated as shown in step 412 exceeds the maximum RPM. If exceeded, the current RPM is assigned to the maximum RPM as described in step 414 and exits the cooling routine as shown in step 422. If the allocated RPM is less than or equal to the maximum RPM, then check that it is less than the minimum RPM as shown in step 416. If less than the minimum RPM as shown in step 420, the RPM is adjusted to the minimum RPM, otherwise it is adjusted to the assigned RPM as shown in step 418. Next, as shown in step 422, exit the cooling routine.

Returning to FIG. 12, step 178 is a compressor check routine. 14 shows the compressor check routine in more detail. With reference to FIGS. 12 and 14, the compressor check routine begins as shown in step 430. The main purpose of the compressor inspection routine is to determine if the compressor is functioning and close the pump if they do not work. Default values for supply pressure, return pressure, and helium assignment are specified as shown in step 432. In general, these values are the default when the pump is cooling, supply pressure = 400 psi, return pressure = 200 psi, and helium assignment = minimum helium, and are pre-values for helium assignment when temperature controlled.

As described in step 434, it is checked via the pump control flow loop whether the compressor check routine has been started for a pre-repetition period. Compressor check causes the test timer to be started simultaneously from the pump control routine. Thus, multiple iterations through the compressor check routine generally occur when the pump is monitored over the test interval. If the compressor check routine is not performed in advance, it is checked whether the pump motor is on as shown in step 436. If not, exit the compressor check routine as described in step 454. If the pump motor is on, check whether the pump is in regeneration mode as shown in step 438. If in regeneration mode, exit the compressor check routine as described in step 454.

If the pump is not in regeneration mode, it records the current operating mode, cooling or on (temperature controlled), and a test timer is specified as shown in step 440. As shown in step 434, the following iteration through the compressor check routine indicates that the compressor check routine is running and checks as shown in step 422 whether the test timer has expired. The test timer allows a predetermined idle interval time taken to monitor the system for normal operation. If the test timer has not yet terminated, exit the compressor check routine as described in step 454 and wait for the next iteration. If the test timer is terminated, a check for cooling mode is performed as described in step 444. If the pump is not in cooling mode, it is determined whether the second stage temperature exceeds a predetermined threshold as shown in step 448. In certain embodiments, the grain boundary is 25K. If the pump has not warmed past a predetermined threshold, the compressor is turned on as described in step 450 and the pump continues to run. Next, if the pump is not cooled, it is determined whether the cooling rate exceeds a predetermined rate, eg 1K per minute, over the test timer interval as described in step 446. If the cooling rate does not exceed 1 K / min, or if the second stage temperature exceeds 25 K, the compressor is turned off and the pump is closed as shown in step 452. Control then passes to step 454 to exit the compressor check routine until the next iteration.

With regard to FIG. 8, the distribution (DPH) state 128 for the layer is also used to handle states beyond normal operating conditions. This is caused by excessive heat load in the vacuum system or damage to the pump or compressor. The main purpose of distribution to the tier is to assign helium to the upper pump in the system and not to less important pumps. In this case, the pump should be completely shut off to allow helium to be used elsewhere.

The system user should enable the Distribution to Tier (DPH) function and define the relative importance of each pump. For example, in certain embodiments, the sputter system consists of two load-lock containers, a buffer container, a delivery container, and four or more processing containers connected to the delivery container. The process vessel pump receives priority 3, the delivery vessel pump is rank 2, and the buffer vessel pump is rank 1. Priority 4 is assigned to the processing container which does not contain a wafer inside. In the case of a fault in the system that causes helium consumption to exceed the required amount, the device controller determines whether any processing vessel has no wafer in it and assigns them a rank 3 or 4. The wafer-less processing vessel causes the allocated helium to be reduced, or the pump is turned off to allow the other vessel to continue operation. Part of the hierarchical system is to cause the system to cause a "light failure." In other words, in the damage system, the wafer has time to finish processing and move from the processing vessel through the transfer vessel to the buffer vessel and back to the load lock which the pump is turned off behind them. The delivery time for this treatment is 1 to 3 minutes. The DPH state 128 first turns off the rank 4 pump at the same time and then turns off the rank 3 order. At the end of the fault condition, the pump is turned on again.

Before the * DPH state 128 begins, the assumption is that there is no valid excess helium flow in the system and the system is above the distribution 124 state for the request. Some pumps work properly with a quota of helium, but none is valid if one or more pumps require more helium. Continued operation warms up one or more pumps. The use of a predetermined layer imposed by the DPH allows the VNC to perform "screening" such that the upper pump cools and the other pumps sacrifice. Priorities of 3 to 5 are common to certain embodiments, and the DPH state 128 allows the user to define priorities, including the rank for each pump in the branch.

The tool host controller dynamically assigns priorities based on results such as the presence or absence of a wafer. The user also wants to maintain a vacuum inside a particular container until it is in constant condition, such as cooling a very hot installation. The user must program in advance whether the pump will be allowed to shut off completely or should be assigned a minimum amount of helium. If the pumps have the same priority, VNC arbitrarily selects one pump in this rank to block or reallocate helium. Operation for other pumps of the same or higher rank is required until system stabilization is achieved.

The VNC also enters the DPH state during pump cooling. In some tools, it is desirable to verify that at least one pump is operating temperature first. Priority is given to these pumps using logic to assign them higher during cooling compared to other pumps in the map.

VNC accepts and stores layer assignments from the tool host computer. If DPH is enabled, the VNC controls the pump using the currently assigned priority. Repetition of priorities by the tool host should be accepted by VNC and DPH works to handle rapidly changing situations.

In another particular example, the helium management control system applies three control modes as described in FIG. 15. The system uses the pressure difference DP to determine the control mode. With respect to FIGS. 1B and 15, the pressure difference is the pressure difference between the high pressure supply 46 line and the low pressure discharge 48 line. In a typical cryogenic pump, the high pressure supply 46 line is about 400 psi and the low pressure discharge 48 line is about 200 psi. The pressure difference is the difference between the two lines and is typically about 200 psi. In extreme cases, when many cryogenic pumps consume helium at high speeds, the pressure differential drops below the critical threshold, whereby the cooling capacity begins to decrease rapidly. One purpose of the system is to prevent the pressure difference from dropping to a threshold.

In the system described in FIG. 15, the control mode is determined as follows: The normal mode occurs when the pressure difference is 190 to 205 psi; Underpressure occurs when the pressure difference is less than 190 psi; The overpressure mode occurs when the pressure difference is greater than 205 psi. The range is approximate and adjusted in the actual system to provide an optional range of pressure differentials corresponding to the control mode.

Continuing with FIG. 15, the flowchart illustrates the operation of the helium management control system using three control modes: normal, overpressure and underpressure. If the pressure differential is outside the range of 190 psi to 205 psi or not in normal mode, the speed of the filter drive motor is controlled to return the system to normal mode. Each of the cryogenic pumps has a temperature target. The target value of the cryogenic pump is the temperature the filter drive motor is trying to achieve during the normal cryogenic pumping temperature. Reducing the target has the effect of increasing the temperature of the filter drive motor, consuming more helium and lowering the temperature of the cryogenic pump. Similarly, increasing the target value tends to allow the cryogenic chiller to warm up, slowing down the strainer drive motor and thus consuming less helium. The target value is used internally by the cryogenic pump to vary the speed of the filter drive motor to match the temperature of the first stage of the cooling finger to the target value using closed loop control or other electronic control mechanism in the cryogenic pump. In addition, both the target value and the strainer drive motor speed have an operating range and do not further modify the motor speed and target value beyond this.

More specifically, the polling interval is terminated as described in step 300 and the system starts another inspection cycle. As shown in step 302, it is checked whether the system is currently in an overpressure mode. If the system is not in the over pressure mode, then check whether the system is in under pressure mode, as described in step 304. If the system is not in underpressure mode, check if the pressure difference is greater than 205 psi, as described in step 306. If the pressure difference does not exceed 205 psi, check that the pressure difference is less than 190 psi, as shown in step 308. If the pressure difference is greater than 190 psi, control returns back to step 310 until the next polling interval ends. Dotted line 312 outlines the sequence of steps that describe normal mode operation as described. This repetition is repeated until the pressure difference is outside the range of 190 to 205 psi and further described below.

The system of FIG. 15 serves to lower the temperature target value and increase motor speed in step 314 below when the pressure difference exceeds 205 psi. If the pressure difference is less than 190 psi, the temperature target value is increased and the motor speed is decreased in step 322 below. After the change, the system is placed in overpressure or underpressure mode for a while, during which no further changes are allowed to stabilize the system.

In step 306, a potential excess pressure condition occurs if the pressure difference exceeds 205. An overpressure condition means that helium is present in the system excessively. Dotted line 314 generally describes the excess pressure correction action. To take advantage of excess helium, the target value of all uncooled cryogenic pumps is reduced by 2K as described in step 316. The drive motor speed of any cryogenic pump under cooling is increased by 15 rpm as described in step 318. The system mode is in over pressure mode as described in step 320, which means that there is excess helium coolant capacity available. It should be noted that there are minimum and maximum drive speed thresholds described further below, which keep the drive motor speed within a predetermined operating range.

Continuing from above, in step 308, if the pressure difference is less than 190, a potential underpressure condition occurs. Underpressure conditions indicate a lack of helium in the system. Dotted line 322 generally describes the steps of correcting underpressure conditions. To conserve helium, as described in step 324, the target value of all uncooled cryogenic pumps is 2K lower. As described in step 326, the drive motor speed of the cryogenic pump under cooling decreases to 15 rpm. Reducing the speed of the chilled cryogenic pump is intended to extend the cooling time but to release excess helium to correct underpressure conditions and to allow pumps operating at normal cryogenic pumping temperatures to continue operating. Next, as described in step 328, the system mode goes to underpressure, meaning that underpressure exists.

Continuing from step 304 above, if an underpressure condition already exists, it should be checked if the underpressure mode continues for more than one minute, as described in step 330. If the current under pressure mode is not present for more than one minute, control returns to step 310 to wait for the next polling interval to avoid system thrashing. If the current under pressure mode continues for more than one minute, it is checked whether the current pressure difference DP is less than the pressure difference that causes the under pressure mode to start as described in step 332. If the underpressure mode has been started beforehand, the system will start to raise the pressure differential, otherwise more aggressive helium management is needed. If the pressure difference DP is greater than or equal to the value that causes the under pressure mode to start, it is checked whether the current under pressure mode lasts for 10 minutes, as described in step 334. If not, control transitions to step 310 to wait for the next polling interval. Thus, the system gives 10 minutes to return to the normal pressure differential range before the system follows more aggressive helium management.

If the pressure differential continues to fall, or 10 minutes have elapsed since the underpressure mode began, the system terminates the underpressure mode, as described in step 336. By ending the underpressure mode, further corrective action starts the next polling interval, which is further described below. Control is transferred to step 310, and as shown in step 300, inspection of step 304 at the next polling interval means that the system is not in underpressure mode. Thus, the pressure difference check of step 308 is that the pressure difference is still less than 190, and the underpressure action 324, 326, and 328 are repeated as described above.

Continuing from the step 302 above, if an excess pressure condition already exists, it is checked if the current excess pressure mode continues for more than 10 minutes, as described in step 338. If not, control returns to step 308 for a small pressure differential check. If the current over pressure mode lasts more than 10 minutes, the system terminates the over pressure mode and control returns to step 300 to wait for the next polling interval, as described in step 340. The system terminates the over pressure mode and begins the over pressure correction test. As shown in step 300, at the next polling interval, the excess pressure mode check control of step 302 proceeds to step 306 because the excess pressure mode is no longer specified. If the pressure difference still exceeds 205, the excess pressure operation of steps 316, 318, and 320 is repeated as described above.

In another particular embodiment, there are four control states and three modes of helium management in the controller further described below. In short, the modes are Ready, Normal and Cool. Preparation is to determine which compressor and cryogenic pump are connected to the system during the initial system preparation. Cooling mode means that one or more cryogenic pumps are performing a cooling operation. Normal mode is when the system is started and all cryogenic pumps have completed initial cooling.

In addition, each of the cryogenic pumps attached to the system has three helium management operating modes reported to the controller. Temperature control (TC) mode means that the cryogenic pump is being controlled by a controller. Cooling (CD) mode means that the cryogenic pump is performing a cooling operation. NONE mode means that the pump can consume helium freely and the drive motor can run at full speed.

The four control states of the helium management control system generally mean that they require more aggressive helium management. The operating state is similar to the control mode described in the above embodiments. Steady state ensures that the helium consumption by all cryogenic pumps 10 in the system is not regulated. The limit test condition is when the pump consumes the same value as the maximum consumption value calculated by the controller. The distribution status for the request occurs when the pump reporting the minimum supply continues to run short after a predetermined threshold time. The distribution of demands causes the system to redistribute excess helium or, in the absence of excess helium, to reduce the maximum helium supply parameter for each cryogenic pump. If all pumps report helium deficiency, the distribution to the bed reduces helium to the less important pump that may be warmed, thereby allocating helium to the critical cryogenic pump according to a predetermined bed.

The cryogenic pump also has a helium consumption state. The OK state means that the cryogenic pump consumes less than 95% of the maximum helium supply parameter. The APPROCHING state means that the cryogenic pump consumes more than 95% of the maximum helium supply parameter. The LIMIT state means that the cryogenic pump consumes helium equal to the maximum helium consumption parameter. The helium consumption state is used to determine if the cryogenic pump consumes the maximum amount of helium needed to maintain the cryogenic pumping temperature, and thus is at the threshold of warming. The approaching state is not used to determine helium management control, but may be queried by the operator as an information item.

16A-16C show a flow chart of the helium management control of the controller 12 described in FIG. 2 in more detail. With regard to FIG. 16A, initial preparation and mapping begins as described in step 610. Initial preparation and mapping determines all compressors 16 and cryogenic pumps 10 connected to the common branch pipe 18. As described in step 610, each cryogenic pump sends and stores the cryogenic chiller size, minimum helium supply, helium consumption rate and cooling completion time in the controller. The controller also receives a valid helium supply from each compressor 16. If each pump has sufficient helium insufficient to support at least the minimum helium supply, the operation is terminated. The initial helium distribution is calculated based on the proportional distribution depending on the cryogenic pump size and sends a maximum helium consumption signal to each cryogenic pump. In addition, the controller reads initial preparation parameters indicating the distribution layer, other operating parameters and defaults, which are further described below.

The controller then starts a control loop, receiving periodic inputs from each cryogenic pump. A parameter signal representing the operational parameter data is received from each of the sensors 14 and the received data is examined to determine if it is valid, as shown in step 612. Control transitions to step 612 until a valid read is obtained. As described in step 614, a check is made to see if the distribution status for the request is activated. As described below with respect to FIG. 16C, the distribution status for the request is activated when the distribution status for the previous request has begun.

If the distribution status for the request is not activated, it is checked whether the limit check status is activated as shown in step 616. The limit test state is activated when the full limit test is positive. When the limit check state is activated, control further described below in connection with FIG. 16B is shifted to step 620. If the limit check state is not activated, then the current consumption state for each cryogenic pump is checked as described in step 618. For any pump that is not in the cold state, the current consumption rate for maximum helium consumption for the cryogenic pump is checked to determine if the limit has been reached. Optionally, to run the system in a more conservative manner, the limit is the percentage of maximum helium consumption, for example 95%. If one or more cryogenic pumps reach the limit, control transitions to step 620, which is further described below with respect to FIG. 16B.

If the limit has not been reached, it is checked whether any cryogenic pump is in the cool state as described in step 622. If none of the cryogenic pumps are in the cooled state, as shown in step 626, the system state is designated normal and control returns to step 612 for the next control loop iteration.

If any cryogenic pump is in the cooled state, the system mode is assigned to cooling as shown in step 624. The cooling operation starts during regeneration or initial system preparation and after the cryogenic cooler has warmed up, reduces it back to normal operating temperature. The cooled state consumes more helium than the normal state. Therefore, the system is checked for excess helium as in the helium redistribution state. The helium surplus for all pumps that are not in cooling mode is calculated and summed to determine the excess helium value as described in step 686. The temporary maximum helium consumption value is calculated at the cryogenic pump being cooled, as described in step 688. In the case where multiple cryogenic pumps are in the cooled state, the temporary maximum helium consumption value is distributed in proportion to the size of each cryogenic chiller, according to the equations further described below in connection with FIG. 17B. Control then passes to step 612 for the next control loop iteration.

Continuing from above, in step 620, a limit check state is started. With regard to FIG. 16B, as shown in step 630, it is checked whether the limit check state is currently active. If not previously activated, the time is recorded as the initial time of the current limit check, as shown in step 632, and the system state is assigned to the limit check, as described in step 634. If a limit check state is already being performed, indicating that the system has already been in a limit check state, the timestamp is recorded as a continuing limit check state as described in step 636. Returning to FIG. 16A, it is checked whether the current limit check continues beyond the predetermined limit check threshold. In certain embodiments, as shown in step 638, it is checked whether the current limit check threshold lasts more than four minutes. If the system is not in the threshold test state for more than 4 minutes, exit the threshold test state as shown in step 638 and control proceeds to the cold test as described in step 622. If the system is in the limit check state for more than 4 minutes, control proceeds to a helium redistribution routine, described further below, as described in step 650. In this way, the system allows the four minute threshold for the threshold check condition to be modified before performing more aggressive helium management.

16A, steps 614 and 638, if helium redistribution is indicated as shown in step 650, control transfers to the helium redistribution state routine shown in FIG. 16C. 16A and 16C, as shown in step 652, the reason for the helium redistribution state started is examined. If the helium redistribution state is not yet activated, a new helium redistribution operation must be performed because the full limit check state does not modify itself within 4 minutes. Check if any pumps report a helium consumption state of OK as described in step 662. If one or more pumps report OK and not LIMIT, helium redistribution is performed using a distribution operation for less aggressive demands. In this relationship, one of the cryogenic pumps consumes helium equal to the maximum helium consumption value and is warmed if no action is taken. System status is assigned to the distribution of requests as shown in step 664, and the controller checks a set of operating parameters for each cryogenic pump. Operating parameters are current helium consumption, maximum helium consumption, helium consumption status (OK, APPROACHING, or LIMIT), and cryogenic operating mode TC (temperature control), CD (cooling or non), and cooling when operating mode is CD Includes completion time.

The average helium surplus is calculated from the operating parameters for each pump, which means the difference between the current consumption of helium and the maximum allowed for each pump as described in step 666. The average helium margin, which indicates excess helium in the system, is used to calculate a new maximum estimate for each pump according to the following equation as described in step 668:

For each cryogenic pump:

Helium Spare = Maximum Consumption-Current Consumption

Average spare calculation:

Average Spare = Sum (Helium Spare) / # of Cryogenic Pumps

For each cryogenic pump:

Max Helium = Current Consumption + Average Spare

New system total helium maximum consumption calculation:

Total System Maximum = Sum (Helium Maximum)

For each cryogenic pump:

New maximum consumption = maximum consumption + (total system effective helium-total system maximum) / # of cryogenic pump.

Thus, excess helium is dispensed by specifying a new maximum consumption for each cryogenic pump based on the total effective helium from the common branch and the maximum total current consumption for all cryogenic pumps. A time stamp indicating the reallocation time is described as shown in step 670. Control then passes to the cooling check of step 622 of FIG. 16A, as shown in step 658.

If the distribution status for the request has already been activated, the time stamp is recorded as a subsequent helium redistribution operation, as described in step 654. It should be determined whether the distribution status for the current request has elapsed beyond the predetermined redistribution threshold. In certain embodiments, the predetermined redistribution threshold is 10 minutes. If the distribution state for the request for more than 10 minutes is ineffective, control returns back to the main control loop of cooling check 622 (FIG. 16A), as shown in step 658. If the helium redistribution mode remains in effect for more than 10 minutes, the redistribution is estimated to effectively redistribute helium, and as described in step 660, the system state is designated normal so that the main loop of FIG. Monitoring at regular intervals. In this way, each iteration through the helium redistribution routine provides 10 minutes for the redistribution to take effect in the system. If redistribution is not aggressive enough, the helium redistribution state is restarted and recalculated to provide more aggressive helium management until the system reaches equilibrium.

If neither pump reports the helium consumption status of OK in step 662, all pumps reach their maximum helium consumption limit and perform helium redistribution using a distribution operation for the more aggressive layer. In this relationship, none of the pumps reported an OK condition, and therefore all pumps are in the LIMIT state, indicating that there is no excess helium in the system. The operating parameters listed above can be read from each cryogenic pump, used to determine the new maximum helium consumption, and one or more cryogenic pumps can be closed.

The system state is assigned to the distribution for the hierarchy, as described in step 672. The current mode of operation of each pump is checked as shown in step 674. As described in step 676, it is checked whether any pump is found to be not in temperature control or cooling. If any pump is not in the TC (temperature control) or CD (cooling) state, it is placed in one of these states as described in step 678 and is switched to step 612 in FIG. 16A to step 680. Wait for the next control interval as shown in.

If all pumps are in temperature control or cooling conditions, the cryogenic pumps should be selected to warm up or reduce their cooling rate. The cryogenic pump hierarchy is read as shown in step 682 to determine which cryogenic pump is the most important and thus continues to receive the supply of helium. Cryogenic pump strata are site-specific tissues of preferential cryogenic pumps that must maintain cryogenic pump temperatures. The bed is modified mechanically based on the activity occurring in the vacuum processing vessel connected to each of the cryogenic pumps. Cryogenic pumps associated with critical processing, such as expensive semiconductor payloads, are generally continuously supplied with helium. Less critical cryogenic pumps designated in the bed will either warm up or reduce their cooling rate. Based on the hierarchy, as shown in step 684, a new maximum helium consumption value is calculated for each cryogenic pump. Next, as shown in step 658, control transfers to step 622 for cooling inspection.

17A-17B show flow charts of cryogenic pump operation. With regard to FIG. 17A, the cryogenic pump control loop begins at 500. As shown in step 500, the information sent from the compressor is checked to verify its validity. The information sent out from the compressor is comparable to the range of normal values. If the information sent is outside the range of normal values, as shown in step 502, the compressor test condition is started and compressor diagnostics are performed. Since the compressor is cooled by the helium it supplies, excess reading means a potentially damaged condition, for example a lack of helium. The compressor check routine determines if the cryogenic pump needs to be closed. If the cryogenic pump is previously closed by the compressor check routine, control returns to step 500 until the system indicates whether the cryogenic pump resumes operation as described in step 504. If the information sent from the compressor is justified, the cryogenic pump verifies that it has not been marked as closed by the compressor inspection routine as shown in step 506. Compressor inspection routines are used to prevent damage to the operation of the compressor running without helium, but also to prevent the pump from closing due to better problems, such as a faulty sensor. If the pump was previously closed by the compressor check routine, the low power recovery routine causes the pump to restart, as shown in step 508.

The cryogenic pump calculates the helium surplus by determining the difference between the current consumption rate and the maximum helium consumption sent out from the controller. The cryogenic pump then determines the helium consumption state based on the redundancy and also determines the current cryogenic operating mode, as described in step 510. Next, the cryogenic pump is checked to see if it is in a cooled state as shown in step 512. If the cryogenic pump is not in a cooled state, it is checked if the pump is in a LIMIT as shown in step 516. The LIMIT operating state occurs when the pump consumes the same helium as the maximum helium consumption parameter sent out from the controller. If the pump operating state is LIMIT, a new maximum helium consumption parameter is calculated and sent out from the controller as described above. The cryogenic pump computes and specifies the drive motor speed corresponding to the maximum helium consumption parameter as described in step 518. Optionally, each cryogenic pump has a minimum and maximum operating range, which takes precedence when the calculated drive motor speed is out of range.

If the pump is in the cooling mode as shown in step 512, a pump cooling routine is triggered as described in step 514. 17B shows a flowchart of the cooling operation. With regard to FIG. 17B, as described in step 520, it is determined whether the second stage temperature is less than 17k. If less, it is determined as described in step 522 whether the first stage temperature is within the target value of 0.5K. If the first stage temperature is within the target value of 0.5K, cooling is completed and control returns to stage 500 until the next polling interval, as shown in stage 524.

If the second stage temperature exceeds 17K or if the first stage temperature is not within 0.5K of the target value, cooling continues and the cryogenic pump benefits from excess helium. The temporary helium maximum is calculated to allocate excess helium according to the following equation.

System excess = sum (extra of all cryogenic pumps)

Maximum Temperature = Current Maximum Consumption + System Excess * (Cryogenic Pump Size / Sum (Cryogenic Pump Size)

Thus, the total excess calculated above is divided based on their size between the cryogenic pumps and added to the current maximum helium consumption parameter as described in step 526. While all cryogenic pumps are allocated a portion of the excess, an alternative embodiment assigns helium according to an optional formula, such as assigning excess helium to only the cryogenic pump being cooled. The temporary drive motor speed is calculated to match the new temporary maximum helium consumption parameter, as also shown in step 526.

Next, the newly calculated drive motor speed is comparable to the minimum and maximum drive motor speed similarly to step 518 above. As described in step 530, it is checked whether the second stage temperature exceeds 40K. If the second stage is more than 40K, then check whether the new temporary drive motor speed exceeds the maximum rpm, typically 144 rpm, as shown in step 530. If the temporary drive motor speed exceeds the maximum rpm, the drive motor speed is designated as the maximum rpm as described in step 532. If the temporary drive motor speed does not exceed the maximum rpm as checked in step 536, the drive motor speed is assigned to the temporary drive motor speed as described in step 538. If the temporary drive motor speed is less than the minimum rpm, the drive motor speed is assigned to the minimum drive motor speed as described in step 540.

If the second stage temperature is less than 40K, then check whether the temporary drive motor speed exceeds 72 rpm as described in step 534. If the temporary drive motor speed is 72 rpm or less, it is designated as the lower of the temporary drive motor speed or the minimum rpm, as described in step 536. If the temporary drive motor speed exceeds 72K, the drive motor speed is specified at 72 rpm, as shown in step 542. In this way, the drive motor tends to run at a temporary drive motor speed or maximum speed until the second stage cools to 40K and tends to run at a temporary drive motor speed or 72 until cooling is complete.

Those skilled in the art can apply the helium management control system in a number of ways to the program that defines its operation and that the methods defined herein include: a) information permanently stored on non-writable storage media, such as ROM devices, b) floppy disks, magnetic Information variably stored on recordable storage media such as tapes, CDs, RAM devices, and other magnetic and optical media, or c) electronic network communications media, such as baseband signals or It should be readily appreciated that this information includes, but is not limited to, information transmitted to a computer via broadband signal technology. The operations and methods are performed by a processor on a software executable object without memory or as a set of instructions contained in a carrier. Optionally, the operations and methods are embodied in whole or in part using hardware components such as application specific integrated circuits (ASICs), state machines, controllers or other hardware components or devices, or combinations of hardware and software components. do.

The systems and methods for controlling helium distribution are particularly shown and described with reference to these embodiments, and it is understood by those skilled in the art that various changes in form and details are possible without departing from the scope of the invention as defined in the following claims. Will be. Accordingly, the invention is not limited by the following claims.

A helium management control system for controlling the supply of helium coolant from a common branch pipe is distributed to each cryogenic pump by monitoring various parameters through sensors to detect and properly redistribute excess and excess helium coolant. This excess helium is switched to another cryogenic chiller that requires it, and when the total cooling demand exceeds the total cooling supply, the coolant supply to the cryogenic chiller is adequately reduced, resulting in a lack of coolant supply. Minimize adverse or slowing effects and maximize coolant utilization.

The above and other objects, features and advantages of the present invention are apparent from the following more detailed description of the preferred embodiments of the present invention, as described in the drawings for the properties relating to the same parts from a different perspective. The drawings are not necessarily to scale, describing the principles of the invention.

1A is a schematic diagram of a conventional conventional cryogenic chiller;

FIG. 1B shows a cross-sectional view of a conventional conventional cryogenic pump including the cryogenic chiller of FIG. 1,

2 shows a block diagram of a cryogenic chiller system main unit controller connected to a number of cryogenic pumps and compressors,

3 shows an example of helium coolant flow rate over time,

4 shows a plot of the helium consumption model used to determine the amount of helium consumed by the cryogenic chiller,

5 shows a block diagram of data and regulatory flow,

6 shows a top flow diagram of the system main unit controller,

7 shows a block diagram of the data flow between the main unit controller, the compressor and the cryogenic pump,

8 shows a state diagram of the main device controller,

9 shows an operational flow diagram of a distribution state for a request,

10 shows a flowchart of the underpressure inspection routine,

11 shows a flowchart of a dispensing routine,

12 shows a flow diagram of a slave device controller of a cryogenic pump,

13 shows a flow chart of a cooling routine,

14 shows a flowchart of a compressor check routine,

15 shows a flowchart of a helium management control in a further specific embodiment using three control states,

16A-16C illustrate a flow diagram of helium management control in a particular embodiment using four control states or modes,

17A-17B illustrate a flow chart of helium management control of a cryogenic pump connected to the controller of FIGS. 16A-16C.

Claims (3)

A compressor reservoir having one or more compressors; A system control method comprising a plurality of cryogenic chillers supplied with coolant from a supply line connected to a compressor reservoir. Determining operating parameters associated with the chiller, including determining a pressure difference between the return line and the supply line connected to the chiller; Assigning a supply of coolant to the chiller based on an operating parameter comprising the pressure difference; Reassigning a supply of coolant in response to a change in operating parameters including a change in pressure differential. The system control method according to claim 1, wherein the supply of coolant assigned to the cooling device is changed based on the speed of the compressor. The method of claim 1, wherein the chiller is included in a cryopump.

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