Plasma Etching Process Temperature Control and Speeding up Plasma

Learn about how the temperature inside the chamber can affect the etching speed in this follow up post to our August 24th post, Temperature Control During Plasma Treatment.

Process temperature is the single most important parameter in the plasma process. Process temperature has primary control over etch rate and has a secondary effect on etch uniformity.
The temperature at which the process operates has a major influence on processing rates. The higher the process temperature, the faster the processing rate.
Process temperature control is mandatory when processing temperature sensitive devices. Uncontrolled process temperatures can cause distortion, delaminating, and discoloration, and can chemically modify the properties of temperature sensitive devices.
• Process temperature is regulated by the patented electrode temperature control system. Electrode temperatures are maintained by continuously recalculating a heat transfer fluid through the electrodes. (See diagram below.)
• The boards are loaded directly onto the temperature controlled electrode surfaces.
• Process temperature is independent of the plasma process and programmable in the range of O°F to 300°F ± 0.5°F.
• An elevated process temperature is selected which is compatible with the type of board material (epoxy, polyimide, acrylic/kapton, Teflon, etc.) being processed, while maintaining maximum processing throughput.
• The temperature control system is a patented feature, unique to the Plasma Etch product line.

Plasma Temperature Control

8 reasons to utilize Plasma Etch Plasma temperature control technology:
1.  Process temperature is constant throughout the plasma sequence. No ramping of temperature occurs during the plasma process. (See graph below.)
2.  Etch rates are predictable and repeatable, due to steady state process temperature.
3.  Etch rates are accelerated by using elevated process temperatures.
4.  No throughput limiting temperature stabilization sequencing (“dummy plasma cycling”) is required.
5.  Start and stop system operation requires no throughput limiting temperature stabilization cycle.
6.  Temperature control is independent of the plasma process.
7.  Temperature control techniques use proven and highly reliable design (recirculation heat transfer fluid). No temperature control elements are exposed to the plasma process.
8.  Any process temperature from 175°F to 300°F may be selected for compatibility with all board materials. Optionally, the temperature range may be extended from O°F to 300°F.

Plasma Temperature

CURVE I (Plasma Etch Temperature Profile)
1. Points A and B are the respective starting and the ending points of the plasma process sequence.
2. Processing temperature is essentially constant throughout the plasma sequence. Any temperature within the control range may be selected and is automatically maintained.
3. Constant process temperature ensures plasma process repeatability.
CURVE II (Typical Competition Temperature Profile)
1. Points C and D are the respective starting and the ending points of the plasma process sequence.
2. The starting temperature at point C is undefined, as it depends on residual system heat from the previous process cycle.
3. The slope of tile temperature profile from point C to point D is dependent on the thermal loading effect of the materials (mass of the load) being processed and the plasma processing parameters (primarily R.F. power level).
4. The ending temperature at point D is a variable, as it is dependent on items 2 and 3 above.
5. The repeatability of the plasma process is severely impaired by this lack of a constant processing temperature.