Heat shield for heater in semiconductor processing apparatus
A heat shield employed in semiconductor processing apparatus comprises a high performance insulation that has low thermal conductivity, such as, below the thermal conductivity of still air over a wide range of temperatures utilized in operation of the apparatus. As an example, the thermal conductivity of the insulation may be in the range of about 0.004 W/m·h to about 0.4 W/m·h over a temperature range of about 0° C. to about 600° C. or more. The deployment of the high performance heat shield reduces the power consumption necessary for the heater by as much as 20% to reach a desired processing temperature as compared to a case of heater power consumption required to reach the same desired temperature without the shield. Further, the heat shield significantly reduces the amount of undesired depositions from gas-entrained constituents on components in the chamber of the apparatus, particularly below or beyond the heat shield, by as much as 90% since the temperature drop is as much as ten orders of magnitude difference.
1. A method of enhancing the efficiency of a semiconductor processing apparatus having a processing chamber within which is supported at least one heater for heating a workpiece supported relative to a first side of the heater, comprising:
providing a heater for heating the workpiece in the chamber for treatment in the chamber via a power source to heat the workpiece to a predetermined temperature;
forming a heat shield having first side adjacent to a second side of the heater so that a substantial temperature differential is established between the heater and a second side of the heat shield;
selecting a high performance insulation for the heat shield having a thermal conductivity below that of still air over a predetermined temperature range to reduce power required to heat the workpiece to the predetermined temperature;
covering the heat shield insulation with a metallic shell;
providing protrusions on an outer surface of the metallic shell to maintain spacing between the metallic shell and the second side of the heater;
flowing purge gas between the metallic shell and the second side of the heater during operation of the heater;
providing a vent to the metallic shell; and
evacuating the metallic shell by evacuating the processing chamber prior to workpiece treatment.
2. The method of claim 1 where the selecting includes selecting high performance insulation having a thermal conductivity within the range of about 0.004 W/m·h to about 0.4 W/m·h.
3. The method of claim 1 wherein the high performance insulation is selected from the group of materials known as Microthem®, Microsil®, and silica aerogels.
4. The method of claim 1 further comprising:
depositing a film on the workpiece via a gas entrained constituent supplied to the chamber; and
selecting a high performance insulation to provide a large temperature differential between the first and second sides of the heat shield to minimize the deposition of gas-entrained constituents on portions of the chamber adjacent and beyond the second side of the heat shield.