System and method for ion source temperature control using symmetric or asymmetric application of force
An ion source is disclosed, in which the compression force applied to the faceplate on the two sides of the extraction aperture may be varied independently. Modifying the compression force between the faceplate and arc chamber can enable temperature control of the ion source by modifying the thermal contact resistance between the two components. This may allow more control of the temperature of the faceplate, and more specifically, the temperature profile across the entire faceplate due to precise control of the thermal contact gradient along the length of the faceplate. The ion implantation system includes two adjustable tension systems, each of which includes an actuator. A controller is used to provide a command signal to each adjustable tension system. In some embodiments, a feedback signal is generated by each adjustable tension system, which is representative of the torque or force experienced by the actuator.
1 . An ion implantation system, comprising:
an ion source comprising:
an arc chamber comprising a plurality of chamber walls and having a first end and a second end; and
a faceplate having an extraction aperture disposed on a top of the plurality of chamber walls;
a source housing, wherein the arc chamber is disposed on the source housing;
a first fastener and a second fastener to press the faceplate against the top of the plurality of chamber walls of the arc chamber, wherein the first fastener is disposed near the first end and the second fastener is disposed near the second end; and
a first adjustable tension system in communication with the first fastener to apply tension to the first fastener and a second adjustable tension system in communication with the second fastener to apply tension to the second fastener; and
a controller, in communication with the first adjustable tension system and the second adjustable tension system, configured to apply different tensions to each fastener.
2 . The ion implantation system of claim 1 , wherein the tension applied to the first end, which is proximate to a cathode in the arc chamber, is greater than the tension applied to the second end so as to increase a temperature of the faceplate.
3 . The ion implantation system of claim 1 , wherein the tension applied to the first end, which is proximate to a cathode in the arc chamber, is less than the tension applied to the second end so as to decrease a temperature of the faceplate.
4 . The ion implantation system of claim 1 , wherein the controller receives an input, and based on the input, determines a desired tension for the first adjustable tension system and a desired tension for the second adjustable tension system.
5 . The ion implantation system of claim 4 , wherein the input is a feed gas species being used, a desired temperature, or a desired force.
6 . The ion implantation system of claim 1 , wherein each fastener comprises a strap, wherein the strap comprises an engagement portion that rests on the faceplate and two attachment portions, where the two attachment portions are coupled to a respective adjustable tension system.
7 . An ion implantation system, comprising:
an ion source comprising:
an arc chamber comprising a plurality of chamber walls and having a first end and a second end; and
a faceplate having an extraction aperture disposed on a top of the plurality of chamber walls;
a source housing, wherein the arc chamber is disposed on the source housing;
a first fastener and a second fastener to press the faceplate against the top of the plurality of chamber walls, wherein the first fastener is disposed near the first end and the second fastener is disposed near the second end; and
a first adjustable tension system in communication with the first fastener to apply tension to the first fastener and a second adjustable tension system in communication with the second fastener to apply tension to the second fastener; wherein each adjustable tension system comprises an actuator and a tension system, wherein the tension system comprises a yoke to attach to a respective fastener, a retaining bracket, and a spring disposed between the yoke and the retaining bracket; and wherein the actuator includes a shaft and wherein movement of the shaft varies a distance between the retaining bracket and the yoke.
8 . The ion implantation system of claim 7 , wherein the source housing comprises a housing body having a cylindrical shape, and wherein flat regions are created on the housing body to mount the tension system.
9 . The ion implantation system of claim 7 , wherein the source housing comprises a flange disposed proximate to the arc chamber, wherein the flange is disposed between the arc chamber and the tension system; and wherein the flange comprises slots through which the fasteners pass.
10 . The ion implantation system of claim 7 , wherein the actuator comprises a linear actuator and the shaft is affixed to the retaining bracket.
11 . The ion implantation system of claim 7 , wherein each adjustable tension system further comprises a ball screw that passes through an interior of the spring and is rotatably coupled to the retaining bracket, wherein the actuator comprises a rotary motor, and a gear disposed at a distal end of the shaft, wherein the gear engages with a ball screw gear that turns the ball screw.
12 . The ion implantation system of claim 11 , wherein the source housing has a hollow interior, and wherein the tension system is mounted on an outside wall of the source housing and the actuator is disposed within the source housing.
13 . The ion implantation system of claim 12 , wherein a slot is disposed in the source housing connecting the hollow interior to the outside wall, wherein the gear extends through the slot to connect the actuator to the tension system.
14 . The ion implantation system of claim 7 , wherein the arc chamber and the source housing are disposed in a vacuum chamber, the tension system is mounted on an outside wall of the source housing and the actuator is disposed outside the vacuum chamber, such that the shaft passes from an atmospheric environment into the vacuum chamber.
15 . An ion implantation system, comprising:
an ion source comprising:
an arc chamber comprising a plurality of chamber walls and having a first end and a second end; and
a faceplate having an extraction aperture disposed on top of the plurality of chamber walls;
a source housing, wherein the arc chamber is disposed on the source housing;
a first fastener disposed near the first end and a second fastener disposed near the second end; and
a first adjustable tension system in communication with the first fastener to apply tension to the first fastener and a second adjustable tension system in communication with the second fastener to apply tension to the second fastener, wherein each adjustable tension system comprises an actuator; and
a controller, in communication with the first adjustable tension system and the second adjustable tension system, to supply a desired tension to each adjustable tension system, wherein the controller supplies a command signal to each adjustable tension system and receives a feedback signal from each adjustable tension system, wherein the feedback signal is indicative of actual tension experienced by each adjustable tension system.
16 . The ion implantation system of claim 15 , wherein the controller updates the command signal to each adjustable tension system based on a respective feedback signal.
17 . The ion implantation system of claim 16 , wherein the controller updates the command signal a plurality of times.
18 . The ion implantation system of claim 17 , wherein the controller updates the command signal at least once per minute.