Temperature control of individual tools in a cluster tool system

• US 20020029877A1
• Filed: 06/13/2001
• Published: 03/14/2002
• Est. Priority Date: 09/16/1997
• Status: Active Grant

• Current Assignee: B/E Aerospace, Inc. (Raytheon Technologies Corporation d/b/a RTX)
• Original Assignee: B/E Aerospace Incorporated (Spirit Realty Capital, Inc.)
• Inventors: Cowans, Kenneth W.
• Granted Patent: US 6,499,535 B2
• Time in Patent Office: Days
• US Class Current: 165/206
• CPC Class Codes: B23Q 11/10 Arrangements for cooling or lubricating tools or work incorporated in tools, see the relevant subclass for the tool , e.g. B23B27/10, B23B51/06, B23C5/28, B23D77/006; for circular saw blades B23D59/02, for cooling grinding surfaces B24B55/02
• CPC Class Codes: B23Q 11/141 using a closed fluid circuit for cooling or heating
• CPC Class Codes: B23Q 11/143 comprising heating means
• CPC Class Codes: F25B 2309/06 Compression machines, plants or systems characterised by the refrigerant being carbon dioxide
• CPC Class Codes: F25B 2341/0681 the sensor is heated
• CPC Class Codes: F25B 40/00 Subcoolers, desuperheaters or superheaters
• CPC Class Codes: F25B 41/20 Disposition of valves, e.g. of on-off valves or flow control valves expansion valves F25B41/31
• CPC Class Codes: F25B 41/335 via diaphragms
• CPC Class Codes: F25B 41/34 with the valve member being actuated by electric means, e.g. by piezoelectric actuators
• CPC Class Codes: F25B 49/02 for compression type machines, plants or systems
• CPC Class Codes: F25B 5/02 arranged in parallel
• CPC Class Codes: F25B 9/008 the refrigerant being carbon dioxide
• CPC Class Codes: F25D 17/02 for circulating liquids, e.g. brine
• CPC Class Codes: Y02B 30/70 Efficient control or regulation technologies, e.g. for control of refrigerant flow, motor or heating

Abstract

A temperature control unit for independent control of a number of independent channels, as can exist with a cluster tool used for semiconductor fabrication, has high efficiency, long term life and reliability, and requires only a small floor area. To these ends, the unit employs a single high capacity refrigeration system and disposes a number of separate temperature control channels for the individual tools, with only some channels receiving refrigerant. Low temperature channels use high pressure, sub-cooled refrigerant for chilling the heat transfer fluid to selected levels controlled by proportional valves adjusting refrigerant flow through evaporator heat exchanger units which cool heat transfer fluid. Moderate temperature channels cool the heat transfer fluid for associated tools to an ambient temperature level. The tools may, as needed, be heated by elements in the separate control channels, the control levels for both cooling and heating being determined by servo circuits programmed to measure actual and establish desired temperature levels.

Claims

1. A system for controlling the temperature levels of a number of tools deployed in a cluster and providing different fabrication functions for a product being manufactured, comprising:

a single refrigeration unit providing subcooled pressurized refrigerant and including a single compressor having capacity adequate for chilling all the tools concurrently desired individual levels;

a pressurized reservoir for thermal transfer fluid;

a source of unchilled coolant;

a plurality of control channels, each including heat exchanger means, a fluid pump, and fluid heater means disposed to define a separate thermal transfer fluid loop in communication with a different tool, and with the thermal transfer fluid reservoir, the control channels comprising at least first and second types, control channels of a first type each having its heat exchanger means coupled to receive the subcooled refrigerant from the refrigeration unit and controllable evaporator means coupled to supply refrigerant to the associated heat exchanger means, control channels of the second type being coupled to receive the unchilled coolant at the heat exchanger means therein; and

regulator means responsive to the temperature of the different tools and coupled to operate the control channels to provide thermal transfer fluid in each channel at a temperature to maintain each respective tool at its selected temperature level.

2. A system as set forth in claim 1 above wherein the regulator means comprises servo control means for each control channel, each including means for sensing the tool temperature, means for generating a control signal representative of the difference between actual and desired tool temperature, and means for controlling the heaters in each control channel, the evaporators in channels of the first type, and the unchilled fluid flow in channels of the second type, to maintain the different tool temperatures at desired levels using the thermal transfer fluid in the associated loop.

3. A system as set forth in claim 1 above, further including valve means disposed in the control channels for selectively shutting off flows in the loops, and further including means in each of the control loops for injecting gas to purge fluid in the individual control loop only.

4. A system as set forth in claim 1 above, including supply and return manifolds coupling each of the control units of the first type to the refrigeration unit.

5. A system as set forth in claim 3 above, wherein the refrigeration unit includes a condenser coupled to the compressor output, the condenser being coupled to the source of unchilled coolant for reducing the temperature of pressurized refrigerant from the compressor, and a subcooler coupled to the output of the condenser for passing the pressurized refrigerant in thermal interchange relation with low pressure returned refrigerant.

6. A system as set forth in claim 5 above, wherein the compressor includes an injection capillary tube coupled to the condenser output, hot gas bypass valve means coupling the output of the compressor to the input, and desuper-heater expansion valve means coupling the output of the condenser to the compressor input.

7. A system as set forth in claim 1 above, wherein the source of unchilled coolant comprises a water feed system for utility water and wherein the control channels of the second type include valve control means coupled in the coolant path to the heat exchanger means for controlling the flow of unchilled coolant in on-off fashion.

8. A system as set forth in claim 1 above, wherein the heat exchangers in the control channels of the first type provide thermal energy interchange between the evaporated refrigerant and the thermal transfer fluid passing from the evaporator in the flow path toward the tool, and wherein the control channels of the first type further include a proportional control valve responsive to a control signal from the regulator means for controlling flow rate through the associated evaporator means.

9. A system as set forth in claim 1 above, wherein the control channels of the first type cover a temperature range from about −

40°

C. to about +100°

C., and wherein the control channels of the second type cover a temperature range from the temperature level of the unchilled coolant to approximately +100°

C.

10. A system as set forth in claim 1 above, wherein the pumps comprise motor/pump combinations, each concentric with a different horizontal axis in the array, with the motors being coaxial with the respective pumps, and the pumps being aligned in a common plane transverse to the axes of rotation, the pumps and the associated conduits in the channels of the first type including exterior insulation means.

11. A control loop system for maintaining the temperature of an operating tool at a selected level within a substantial temperature range that includes levels above and below the ambient, using a chilled pressurized refrigerant and a thermal transfer fluid, comprising:

means defining a control loop for a thermal transfer fluid communicating in thermal interchange relation with the tool, the loop further including pump means for the thermal transfer fluid;

electrical heater means disposed in the control loop between the pump and tool and controllable in response to an energizing temperature control signal;

heat exchanger means in the loop and receiving the thermal transfer fluid and the chilled refrigerant;

proportional valve means coupled to receive the chilled refrigerant in the heat exchanger means for controlling the flow of chilled refrigerant in the heat exchanger means such as to maintain a selected below ambient temperature in the thermal transfer fluid transferred to the tool, and

means coupled to the heater means for controlling the heater means to alternatively maintain a selected temperature level that is above the ambient in the thermal transfer fluid.

12. A system as set forth in claim 11 above, wherein the refrigerant is a subcooled refrigerant and the control loop system receives the refrigerant and wherein the heat exchanger means includes an internal evaporator coupled to receive the refrigerant at a rate controlled by the proportional valve means and providing a vaporized refrigerant at a temperature to cool the thermal transfer fluid to a selected level.

13. A system as set forth in claim 11 above, wherein the proportional valve means comprises a proportional integral derivative system including a valve element means for controlling refrigerant flow rate to the evaporator, the proportional valve means comprising chambers defining first and second interior volumes confining a pressurized gas and including an interconnecting gas conduit, and the chamber defining the first volume being in thermal communication with a thermal energy source controlling the internal pressure in the first interior volume, the chamber defining the second interior volume including a flexible diaphragm and a valve stem, the flexible diaphragm forming a moveable wall of the second interior volume, the valve stem controlling refrigerant flow in accordance with its position, and being controlled in position by the pressure in the second interior volume.

14. A system as set forth in claim 11 above, wherein the fluid pump means comprises a pressurizing pump having an inlet and outlet, and where the system further includes conduits coupling thermal transfer fluid from the control loop system to the tool whose pressure is to be maintained, and valve means at the input and output lines at the control loop subsystem, for selectively closing off the inlet and outlet lines, and wherein the system includes pressurized gas injection means coupled to the control loop system such that thermal transfer fluid can be driven out of the conduits and a selected tool, and the conduits and tool can be isolated for maintenance or replacement purposes.

16. A system as set forth in claim 15 above, wherein the conduit loops each include a pressurizing pump, and a closely spaced motor coupled to and drive the pump, and wherein the motor is collinear with the pump and coupled by a common shaft and includes a separating pump mount thermally isolating the pump from the motor, and wherein the motor includes a shaft hydrodynamically supported by pressurized heat transfer fluid at substantially constant temperature.

17. A system as set forth in claim 14 above, wherein the refrigeration unit has a refrigeration capacity at a predetermined temperature level that is sufficient to meet the total refrigeration demand of all of the conduit loops, and wherein the temperature variations in the heat transfer fluid can be in excess of +100°

C.

18. The system as set forth in claim 14 above, wherein the system receives cooling fluid from an unrefrigerated source, and wherein the heat exchangers comprise a first type providing thermal interchange between the refrigerant and the heat transfer fluid, and a second type providing thermal interchange between the unrefrigerated cooling fluid and the heat transfer fluid.

19. The system as set forth in claim 14 above, wherein the conduit loops include valve connections providing outlets to and returns from the controlled units, the valve connections including shut-off valves, and the system further including conduit lines coupling the valve connections to and from the individual controlled units.

20. A system as set forth in claim 19 above, wherein the system includes means for providing a pressured purge gas to at least some of the conduit loops to drive heat transfer fluid from one or more selected controlled units and the conduit lines coupled thereto into the pressurized reservoir.

15. A system for separately controlling the temperature of a number of controlled units using heat transfer fluid and comprising:

a supply reservoir providing pressurized heat transfer fluid;

a single refrigeration unit providing high pressure refrigerant;

a number of conduit loops receiving refrigerant from the refrigeration unit and heat transfer fluid from the reservoir and coupled to circulate heat transfer fluid through the associated controlled unit, each of the conduit loops also including an evaporator receiving the refrigerant from the refrigeration unit and a heat exchanger for interchanging thermal energy between the heat transfer fluid and the refrigerant;

servo control means for each of the conduit loops, each servo control means storing temperature values desired for the controlled units and including means for sensing the actual controlled unit temperature and providing a control signal to indicate a needed correction; and

a number of proportional control valves, each disposed in a different conduit loop between the refrigeration unit and the evaporator for controlling refrigerant flow thereto in response to the control signals, to maintain the temperatures of the heat transfer fluid and the controlled units at a desired level.

21. A system occupying a low volume, but providing adequate refrigeration capacity and temperature control for individual tools having varying temperature maintenance requirements, while permitting convenient coupling and servicing, comprising the combination of:

a rectangular open-sided frame for containing all the interior units;

a single refrigeration unit mounted within the frame and having a refrigeration capacity substantially equal at a minimum to the maximum refrigeration demand of the tools;

a plurality of pump/motor combinations arrayed within the frame along adjacent horizontal axes, the pumps being collinear with the motors;

a plurality of heat exchanger units disposed adjacent the pump/motor combinations, the heat exchanger units being coupled in temperature control loops to different ones of the pump/motor combinations and including heater means in at least some of the loops, the heat exchanger means comprising both a first type having means for cooling the heat transfer fluid only with an unchilled liquid, and a second type for cooling the heat transfer fluid with refrigerant from the refrigeration unit, wherein the lowest temperature attainable is substantially below ambient;

the heat exchangers of the second type receiving refrigeration fluid in separate and parallel temperature control loops, each in thermal intercommunication with heat transfer fluid to be supplied to a different tool;

a plurality of control means, each associated with a separate temperature control loop for controlling the temperature of the heat transfer fluid to a different tool, and providing the heat exchangers of the first type with an on/off binary-controlled flow of unchilled liquid, and providing heat exchangers of the second type with a proportional flow of expanded refrigerant; and

wherein the system further comprises a pressurized reservoir for heat transfer fluid and a pressurized reservoir for refrigeration fluid feeding the parallel control loops.

22. The method of controllably regulating the separate temperatures of at least a number of the tools in a cluster tool comprising the steps of:

passing pressurized heat transfer fluid in individual thermal exchange relation with different separate tools;

providing a single flow of refrigerant having refrigeration capacity adequate for the concurrent refrigeration maximum of at least some of those of the tools that are to be refrigerated below ambient level;

branching the refrigerant into separate heat exchange paths in thermal interchange relation with the heat transfer fluid, one path for each control loop associated with a tool that is to be lowered below ambient temperature;

providing separate control signals representative of the current temperature level desired for the different individual tools; and

individually controlling the temperatures of the heat transfer fluids in each of the separate control loops by varying the temperatures of the refrigerants in those branches to maintain the temperatures of the tools at their desired levels.

23. The method as set forth in claim 22 above, wherein the refrigerant is provided as a high pressure subcooled refrigerant and wherein the step of varying the temperature of the refrigerant in the branches comprises evaporating refrigerant at a rate in each branch responsive to the control signal for the control loop to establish a desired lower temperature.

24. The method as set forth in claim 23 above, wherein the tools are at times to be raised in temperature above the ambient level, and wherein the method further comprises the step of heating the heat transfer fluid in the control loops in accordance with the control signals and the method further comprises the step of returning the refrigerant to a single flow for recompression after evaporation.

25. The method as set forth in claim 24 above, wherein the cluster tool includes at least one tool that need be cooled only to an ambient level, and wherein the method further comprises the steps of providing a coolant at ambient temperature level, passing the ambient temperature level in thermal interchange relation with the heat transfer fluid for the associated at least one control loop, and varying the temperature of the heat transfer fluid to be provided to the at least one associated tool by varying the flow of the ambient coolant in on/off fashion.

26. A method as set forth in claim 25 above, further including the step of varying the rate of evaporation of refrigerant in the different branches by proportional control including a temperature responsive compressible fluid in each branch, and further initiating rapid cooldown by a separate flow of low temperature evaporated refrigerant at cooldown transitions indicated by the control signals.

29. A unit as set forth in claim 28 above, wherein the pumps comprise motor-pump combinations, each motor being coaxial with its pump along its separate axis and rotatable thereabout, the horizontal axis of the pumps being substantially parallel.

30. A unit as set forth in claim 29 above, wherein the frame has reactively broad front and back faces, one of which is the first open side.

31. A unit as set forth in claim 29 above, wherein the frame has relatively narrow open side faces and wherein the each of the pumps in the array is disposed along a different substantially parallel horizontal axis transverse to the side faces and the inlets and outlets are disposed adjacent a single one of the side faces.

32. A unit as set forth in claim 28 above, wherein at least some of the heat exchangers include evaporators receiving refrigerant, and proportional controllers in the refrigerant couplings to the evaporators for controlling the flow to maintain the desired fluid temperature, the heat exchangers and evaporators being disposed below the pump array.

33. A unit as set forth in claim 32 above, wherein the unit includes means for receiving unchilled coolant from an external source and wherein the heat exchangers are divided into two groups, a first group including evaporators and receiving refrigerant from the refrigeration unit, and the second group including heat exchangers receiving the unchilled coolant.

34. A unit as set forth in claim 28 above, wherein the unit further includes separate heaters in each of the temperature control conduits, for selectively heating the thermal transfer fluid therein.

35. A unit as set forth in claim 28 above, wherein the pumps for control conduits receiving refrigerant from the refrigeration unit are disposed in a separate lower set relative to the other pumps, and wherein the unit further includes insulation disposed about the refrigerant receiving pumps and the associated conduits for the heater interchange fluid.

36. A unit as set forth in claim 28 above, wherein the single refrigeration unit includes a compressor having approximately 10 HP for providing approximately 4000 watts of refrigeration capacity at −

40°

C. for the control conduits, the unit having a footprint of approximately 12″

×

34″

.

38. The method as set forth in claim 37 above further including the step of refilling the lines and the tool with thermal control fluid including the steps of:

opening both the first and second lines at the control unit;

venting the connected lines to atmosphere near the tool; and

allowing the pressurized thermal control fluid to flow from the source into the lines and the tool.

39. The method as set forth in claim 38 above, further including the steps of:

determining when fluid has been driven back toward the source through the said other line by observing the presence of at least bubbles in the line;

maintaining the pressurized thermal fluid control source at a pressure of 10-25 psi;

pressurizing with a gas pressure of greater than 25 psi; and

continuing the refilling until liquid appears at the venting point.

27. The method for controllably regulating the separate temperatures of different devices with a single temperature control unit comprising the steps of:

passing pressurized heat transfer fluid in individual thermal exchange relation with different ones of the devices;

providing a single flow of subcooled, pressurized refrigerant adequate in refrigeration capacity to meet the demands for refrigeration of the different devices;

branching the subcooled refrigerant into separate heat exchange paths for the different devices; and

individually controlling the temperatures of the different devices by evaporating the refrigerant in the separate branches at different flow rates.

28. A compact unit having a low footprint area, for controlling, with heat interchange fluids, the temperature of each of a number of different fabrication tools which may be arranged in a cluster, comprising:

an open frame delineating an open interior volume of rectangular form and including a horizontal base of the requisite small footprint area and open sides, one of which is accessible to the tools;

an array of heat interchange fluid pumps mounted in the frame, each disposed about a different horizontal axis in an upper region of the frame, the pumps including inlets and outlets accessible at a first open side of the frame for individual coupling to the tools;

a number of heat exchangers disposed below the pump array within the frame;

a common heat transfer fluid tank mounted within the frame adjacent the array of pumps, and coupled thereto;

a number of temperature control conduits coupling the inlets and outlets of the different pumps to different heat exchangers in separate control loops; and

a single refrigeration unit mounted within the frame adjacent the array and including a compressor having adequate refrigeration capacity for the total refrigeration demand of the different tools, and the compressor being coupled to supply chilled refrigerant to at least some of the heat exchangers.

37. The method of removing pressurized thermal control fluid from a selected semiconductor fabrication tool connected by input and output lines to a temperature control unit including a pressurized thermal control fluid source comprising the steps of:

closing off the lines at the temperature control unit;

feeding a gas under pressure into one line in the region of a low point in the lines while coupling a region of the other lines adjacent the tool to the fluid source to drive thermal control fluid from the low point in the first line, the tool and, from a part of the second line into the pressurized thermal control fluid source;

opening the said one line at the temperature control unit;

feeding the gas under pressure into the said other line adjacent the tool to drive the thermal control fluid remaining in the said other line and tool back into the source; and

closing off both lines.

40. The method of isolating a tool in a cluster tool from a source of heat transfer fluid conducted to and from a control channel by a pair of disconnectable lines, at least one of which is below the tool, comprising the steps of:

providing a source of pressurized heat transfer fluid to the lines;

first purging the heat transfer fluid from a part of the disconnectable lines by driving the fluid under gas pressure from a low region of the lines through the tool and toward the source from a point near the tool;

again purging the heat transfer fluid from a part of the disconnectable lines by driving the fluid under gas pressure from the point near the tool and through a part of the control channel toward the source;

disconnecting the tool from the control channel for appropriate servicing or replacement;

reconnecting the tool to the control channel; and

refilling the control loop from the pressurized reservoir.

41. The method as set forth in claim 40 above, wherein the pressure of the purging gas is higher than the pressure of the reservoir, and further including the steps of venting gas from the interior of the control loop after reconnection, and refilling the interior loop until liquid begins to vent from the system.

42. In a system that provides heat transfer fluid to a number of tools in separate loops, to provide temperature control of the loops, a subsystem for enabling individual tools to be cleared of heat transfer fluid comprising:

a single pressurized reservoir for the heat transfer fluid;

a number of control loops for individual control systems for the different tools, the control loops including return ports and outlet ports, each having an associated flow control valve;

a number of tool conduit systems, each for a different tool, and each including return and input lines connectable to the return and outlet couplings respectively for the different tools, each conduit system including a low point below the tool;

a number of purge gas inputs, each coupled to a different control loop conduit adjacent at least the low point;

therein;

a source of pressurized gas available to be coupled to the purge inputs to the control loops; and

at least one heat transfer fluid line, adapted to be coupled between the source of pressurized heat transfer fluid and a chosen one of the control loops, at the low point, whereby by coupling the source of purge gas to a purge gas input in a control loop, heat transfer fluid is driven out of the tool loop toward the pressurized reservoir.

43. A subsystem as set forth in claim 42 above, wherein the conduits in the loops are of larger diameter than the purge gas couplings and the feeder lines, and wherein the heat transfer fluid pressure in the reservoir is sufficient to refill the tool loop conduits after reconnection of the return and input lines to the control loop and opening of the flow control valves.

44. A temperature control unit configuration for providing multiple temperature controlled fluid lines for different tools in a cluster, each tool to be independently temperature controlled, while the temperature control unit occupies minimal floor area and allows independent servicing of the tools, comprising:

a frame having the desired low floor area, the frame having at least one substantially vertical and open access side;

a plurality of pump/motor combinations arrayed within and coupled to the frame within a first interior volume of the frame, the pump/motor combinations being disposed about separate horizontal axes and arrayed together adjacent the access side;

a plurality of return line couplings, each disposed on the access side of the frame adjacent the first interior volume and coupled to different ones of the pumps for intercoupling to the different tools;

a plurality of outlet line couplings disposed in a vertical plane adjacent the access side of the frame and adjacent the first interior volume, the outlet line couplings being coupled to different ones of the pumps and available for intercoupling to the different tools;

a plurality of temperature control means disposed within the frame and below the first interior volume, the temperature control means including heat exchanger means;

a single refrigeration unit including compressor and condenser means disposed within the frame, adjacent and to one side of the first interior volume;

a refrigeration unit disposed within the frame adjacent the opposite side of the frame from the first interior volume;

a plurality of conduits coupling refrigerant from the refrigeration unit to those of the heat exchanger means requiring refrigeration; and

a source of pressurized heat transfer fluid within the frame above the refrigeration unit and coupled to each of the heat exchanger means.

45. The system as set forth in claim 44 above, wherein the compressor is mounted on the base area of the frame, wherein the heat exchanger units receiving refrigerant include evaporator units mounted below the first interior volume;

and wherein the system further includes a refrigerant receiver vessel mounted on the base area of the frame on the opposite side from the compressor and on the access side of the heat exchangers.

46. A system as set forth in claim 45 above, wherein the system further includes proportional integral derivative devices disposed on the access side of the heat exchangers and coupling the refrigerant to the evaporators, and further includes solenoid valves coupling ambient cooling fluid to other heat exchangers, and disposed between the pressurized heat transfer fluid source and the first interior volume.

48. A system as set forth in claim 47 above, wherein the system further comprises at least one channel for moderate temperature cooling, and includes at least one moderate temperature heat exchanger receiving thermal transfer fluid and an ambient temperature coolant, and at least one control for regulating the thermal transfer fluid temperatures thereof, and wherein the frame structure is of rectangular form with relatively broad side faces and relatively narrow end faces.

49. A system as set forth in claim 48 above, wherein the access side is one of the broad side faces and where the pump/motor combinations lie along axes perpendicular thereto and wherein the channels comprise a number of evaporator/heat exchanger units and a number of moderate temperature heat exchangers.

50. A system as set forth in claim 48 above, wherein the access side is one of the narrow end faces and where the pump/motor combinations lie along axes perpendicular thereto and wherein the channels comprise at least one evaporator/heat exchanger units and at least one moderate temperature heat exchanger.

47. A compact system for delivering thermal transfer fluid in different channels at adjustable temperature levels to control the temperatures of different tools, comprising:

a frame structure having a low area base and frame elements extending vertically therefrom to provide containment for the components of the system, the frame structure having at least one vertical, open, access side;

a number of adjacent pump/motor combinations disposed along parallel rotational axes in an array in an upper region of the frame structure, the pump/motor combination having an inlet and outlet ports disposed adjacent the access side;

a refrigeration unit including a compressor mounted in a lower region of the frame structure, the refrigeration unit providing a pressurized, low temperature refrigerant in liquid phase;

at least one evaporation/heat exchanger unit coupled to one of the pump/motor combinations and receiving both pressurized refrigerant and thermal transfer fluid in an individual channel, the at least one evaporator/heat exchanger unit being disposed between the pump/motor array and the refrigeration unit; and

at least one controllable thermal expansion valve disposed between the refrigeration unit and the at least one evaporator/heat exchanger unit for regulating the temperatures of the thermal transfer fluid thereof.

51. A temperature control unit for coupling to a cluster of semiconductor fabrication tools to control the temperature of each tool separately in accordance with an individual program for that tool, comprising:

a number of temperature control channels, each including operative elements physically intermingled with elements from other channels, and each having a heat exchange loop coupled to a different fabrication tool, the channels each including a common coolant and a separate pressurizing pump for the coolant;

a refrigeration system having a plurality of operative elements disposed in distributed relation among the temperature control channels, and including a refrigerant distribution and return system;

a heat exchange system coupling the refrigerant distribution and return system to at least one of the heat exchange loops, the heat exchange system also being distributed among the elements of the temperature control channels; and

the unit having all the operative elements thereof disposed within a volume of less than about two cubic feet per channel.

52. A unit as set forth in claim 51 above, wherein there are at least two heat exchange loops receiving refrigerant for temperature control, and the unit occupies less than about 0.7 square feet floor space per channel.

53. A unit as set forth in claim 52 above, wherein the system includes a pressurized reservoir for the common coolant and wherein the heat exchange loops are each sealed fluid systems.

54. A unit as set forth in claim 53 above, wherein the refrigeration system provides high pressure, relatively low temperature refrigerant, and the heat exchange system for each branch includes a different evaporator for receiving the controlled refrigerant flow for selectively cooling the temperature of the heat exchange fluid, and wherein at least one of the temperature control channels includes heating means in thermal exchange relation with the heat exchange fluid.

55. For separately controlling the temperature of a number of processing tools with a heat exchange fluid, a method comprising the steps of:

providing a flow of pressurized low temperature refrigerant having sufficient refrigeration capacity for the total concurrent needs of the processing tools;

flowing the refrigerant into different branches, one for each tool to be refrigerated;

controlling the refrigerants flows in the different branches in accordance with desired temperatures by lowering the pressure of the refrigerant in each branch to a selected individual level; and

circulating the heat exchange fluid in separate loops in thermal relation to the tools and to the controlled refrigerant flows.

56. A method as set forth in claim 55 above, further including the step of selectively heating heat exchange fluid in selected ones of the heat exchange loops to raise the temperature of the processing tool above the ambient level.