Patent Application
20150053375
The instant invention is directed to a multi-loop temperature control system for a semiconductor manufacture process, a control valve used therein, and a process for manufacturing semiconductors.
The need for specialized thermal control systems for use in the manufacture of semiconductor devices is known. For example, see U.S. Pat. Nos. 6,026,896, 7,069,984, 7,225,864, 6,822,202, 7,180,036, 7,870,751, and 8,410,393, each of which is incorporated in its entirety herein.
U.S. Pat. No. 6,026,896 teaches a heat exchanger, a manifold coupled to the heat exchanger, a plurality of fluid passages coupled to the manifold, a flow control valve in each fluid passage, and a process component associated with each fluid passage, FIG. 1. The controller may control the temperature of a device with multiple process components, FIG. 2. The controller may have two manifolds for distributing heat transfer fluid at differing temperatures, FIG. 3. The valve 74 is a 3-way valve for mixing the heat transfer fluids of the differing temperatures.
U.S. Pat. No. 7,069,984 & U.S. Pat. No. 7,225,864 teach a remote temperature control module (RTCM) for use in a temperature control system for a semiconductor process component. The RCTM includes a loop to the source of cooling fluid, a loop to the process component (tool), a heat exchanger thermally connecting the loops, and may include a heat source (362). The cooling loop includes a control valve coupled to a temperature controller.
U.S. Pat. No. 6,822,202 & U.S. Pat. No. 7,180,036 teach a temperature control system for use in a semiconductor process component. This system includes a loop to the process component, a loop to a first source of fluid, and a loop to a second source of fluid. The first and second fluid sources are at different temperatures. The first and second fluids are used, by mixing with the fluid of the process component loop, to control the temperature at the process component.
U.S. Pat. No. 7,870,751 teaches a temperature control system for use in a semiconductor process component. This system includes a first loop to multiple processing components arranged in parallel (FIGS. 2 & 5), a second loop coupled to a chiller, a heat exchanger thermally connecting the first and second loops, a control valve and heater on each line from the first loop to the process component.
U.S. Pat. No. 8,410,393 teaches a temperature control system for use in a semiconductor process component. This system utilizes, for example see FIG. 5A, a set of recirculators, 510/520/530/540, each at a different temperature, and switching valves 561/562, to circulate fluid to the process component to control the temperature at the process component.
While each of the foregoing devices has served well, there is a continuing need for the improvement for these specialized semiconductor manufacturing temperature control devices. Heretofore, semiconductor processes where conducted one step at a time. For example, one etch or material deposition step was performed on a wafer, and then the wafer was moved to the next step. Or, only one layer of the wafer was worked in a given step. Now, however, there is a need to increase throughput in these manufacturing processes. As progress is made to increase the size of the wafers, for example to 450 mm or more, there will be increased efforts to perform multi-step etchings and depositions, as well as, multi-layer etchings and depositions that are performed without movement of the wafer (which increasing the chance of, for example, particle contamination). These multi-step and multi-layer processes will require, among other things, more demanding temperature control because the etch/deposition rate, resolution (selectivity), and etch/deposition control for each step must be tailored to the process involved. Each of these considerations will require, for example, attention to fine temperature control to facilitate the process step, quick temperature set point movement from step-to-step, and varying power consumption (heating/cooling demand) for each step. Accordingly, there is a need for a new temperature control system for use in the semiconductor manufacturing process.
A temperature control system for a semiconductor manufacturing process having at least one target includes: a heat exchange loop operatively associated with each target, and a mixing valve operatively associated with each heat exchange loop. This mixing valve has a body defining a mixing chamber. The mixing chamber has an inlet, an outlet, a hot inlet, a cold inlet. A closure means is associated with each inlet. Alternatively, the mixing valve may include: a body defining a mixing chamber, the mixing chamber having an inlet, an outlet, a hot inlet, and a cold inlet, a moveable gate operatively associated with each inlet for controlling the flow of fluid through said inlets, and a motor for moving the gates. A process for manufacturing semiconductors includes the step of providing a temperature control system having at least one target including a mixing valve operatively associated with each target, the mixing valve having a body defining a mixing chamber, the mixing chamber having an inlet, an outlet, a hot inlet, a cold inlet, and a closure means associated with each inlet.
For the purpose of illustrating the invention, there is shown in the drawings a form that is presently preferred; it being understood, however, that this invention is not limited to the precise arrangements and instrumentalities shown.
a-d are schematic illustrations of a gate of the inventive mixing valve.
a-c are illustrations of inventive temperature control system in operation with a representative sample of the programming logic of the controller.
Referring to the figures, where like element have like numerals, there is shown in
For the purpose of illustration,
Target, as used herein, refers to semiconductor processing equipment or semiconductor processing techniques/steps used to convert the virgin wafer into a semiconductor device(s) or semi-work semiconductor. These targets include any process by which the wafer is converted to a semiconductor(s) or semi-work semiconductor(s). Such process are well known and include, for example: deposition processes—chemical vapor deposition (CVD), plasma-enhanced chemical vapor deposition (PECVD), cupper deposition, sputter deposition; etching—dry etching, plasma etching, electron beam evaporation; resist strip, to name a few. The system described, hereinafter, may have particular relevance to etching processes, and/or those processes conducted in vacuum chambers. In operation, the wafer within the target and is thermal communication with the system 10. As the various processes are used to convert the wafer in the semiconductor, the system 10 may be used to control the temperature (as well as the removal or input of heat into the wafer) as may be required to facilitate the completion of the process.
In general, system 10 is coupled to a cold loop 18 and a hot loop 24. The terms cold and hot are relative terms and are used to indicate differing temperatures. The exact temperature of cold and hot will be dictated by the requirements of the processes discussed above. It is desirable that the temperature difference between the hot and cold loops be as great as possible. These larger temperature differences facilitate quick change of the set point at the target. As an example, the system may have: a cold loop temperature (Ta) of −20° C. and a hot loop temperature (Th) of 150° C.; or a Tc of 0° C. and a Th of 120° C.; or a Tc of 10° C. and a Th of 100° C. (or any combination or subcombination therebetween of the temperatures in those ranges). Coupling may be in any fashion, but typically refers to a parallel coupling, as opposed to a series coupling. Cold loop 18 includes a cold loop feed 20 and a cold loop return 22. Additionally, the cold loop 18 may include a cold loop temperature sensor 19, for example in feed 20. Hot loop 24 includes a hot loop feed 26 and a hot loop return 28. Additionally, the hot loop 24 may include a hot loop temperature sensor 25, for example in feed 25. There may be more than one temperature sensor in the respective loops. The temperature sensors are operatively connected to a controller 50.
System 10, referring generally to the left hand side of
Mixing valve 100, discussed in greater detail below, has a process inlet 102, a process outlet 104, a cold inlet 106, and a hot inlet 108. The cold loop 18 is in thermal communication with the cold inlet 106 of valve 100. Heat exchange fluid is drawn from the cold loop feed 20 through a flow sensor 42, operatively connected with controller 50, to one side of a heat exchanger 44 and returned to cold loop return 22. The cold inlet 106 is in fluid communication with another side of the heat exchanger 44. The hot loop 24 is in thermal communication with the hot inlet 108 of valve 100. Heat exchange fluid is drawn from the hot loop feed 26 through a flow sensor 46, operatively connected with controller 50, to one side of a heat exchanger 46 and returned to hot loop return 28. The hot inlet 108 is in fluid communication with another side of the heat exchanger 46.
System 10′, referring generally to the right hand side of
In operation, the heat exchange fluid is in thermal communication with the wafer held within the target 14, for example, by a wafer chuck (not shown) of the target 14, and is pumped to the mixing valve 100 by means of the pump 32. In a steady state mode, the fluid is circulated through valve 100, 100% in and 100% out via process inlet 102 and process outlet 104. However, when the temperature set point needs to be changed (increased or decreased as may be demanded by the process being conducted at the target 14), the mixing valve comes into active operation. The mixing valve 100 selectively mixes, as will be discussed below, cold or hot fluid via cold inlet 106 or hot inlet 108, while reducing flow at inlet 102, and thereby changes the temperature of the fluid exiting outlet 104. All of these being controlled by controller 50 which receives input from the noted flow and temperature and outputs instruction to the mixing valve 100.
The mixing valve 100 is shown in greater detail in
In
In
The body 110, see
Motor 118, see
Motor 118 may be any motor capable of moving gates 114/116. Motor 118′s operation is controlled via a connection to controller 50. Motor 118 is operatively connected to gates 114/116 via an actuator 120. Actuator 120 may be mounted in body 110 via a bearing 122. As shown, motor 118 is a stepping motor that rotates actuator, e.g., a threaded rod. The gates 114/116 are mounted on actuator 120, so that as actuator rotates, the gates 114/116 open and close inlets 102/106/108. While motor 118 is shown as a stepper motor, it is not so limited and other mechanisms may be used to move gates 114/116. Such mechanisms include, without limit, servomotors, linear motors, and hydraulic motors.
Gates 114/116 are configured in such a way that by action of the actuator 120, they open and close the inlets 102/106/108. This is best illustrated by comparison of
In
As will be apparent to those of ordinary skill, the temperature and volume (or mass) of the cold/hot fluid will control the time it will take to decrease/increase the temperature of the fluid circulating in the process loop to the target 14. It should be noted, that as gates 114/116 open/close cold/hot inlets 106/108, the gates 114/116 close the inlet 102, so that a material balance (inflow=outflow) is maintained around the mixing chamber. To more fully illustrate this point, the following non-limiting example is provided, it being understood that there may be other methods for determining the necessary parameters.
In
a is a graph of the temperature profile at the target 14. The x-axis is time (tx, x=0, 1, 2, 3 . . . n, & t′x, x=0, 1, 2, 3 . . . n). The y-axis is temperature (the temperatures are for illustration only and may be changed as dictated by the processes being carried out at the target). As illustrated, the first temperature set point is 40° and is held until t1, then the temperature is ramped to 80° over the time interval of t1 to t′1 and then held there until t2, then the temperature is ramped down to 0° over the time interval of t2 to t′2 and then held there until t3, and finally, the temperature is ramped to 40° over the interval of t3 to t′3 and held there. The phantom lines above and below the solid temperature profile line represent the fine temperature control.
b is a graph of gate position as a function of time. The x-axis is time (tx, x=0, 1, 2, 3 . . . n, & t′x, x=0, 1, 2, 3 . . . n). The y-axis is gate position (the gate positions are for illustration only and may be changed as dictated by the processes being carried out at the target).
c is chart illustrating how the controller 50 may be programmed to implement the gate position of
The present invention may be embodied in other forms without departing from the spirit and the essential attributes thereof, and, accordingly, reference should be made to the appended claims, rather than to the foregoing specification, as indicating the scope of the invention.
