Control of stray radiation in a cvd chamber

A method for limiting stray radiation received by a radiation thermometer viewing a target in a chemical vapor deposition chamber, the method comprising:

• providing a wafer carrier and a heater array configured for operation within said chemical vapor deposition chamber, said wafer carrier being configured for rotation about a rotation axis and having a lower surface and a substantially planar upper surface, said upper surface defining a target plane, said heater array including a peripheral heating element that includes a low heat flux portion along a designated portion of said peripheral heating element;
• providing instructions on a tangible medium, said instructions comprising:
• disposing said heater array within said chemical vapor deposition chamber;
• disposing said wafer carrier within said chemical vapor deposition chamber above said heater array and with said upper surface facing upward;
• aligning a radiation thermometer to view a target proximate an axis of reduced scattered radiation, said axis of reduced scattered radiation being coplanar with said target plane and extending from said rotation axis and over said low heat flux portion of said heating element.

A system for limiting stray radiation received by a radiation thermometer, comprising:

• a chemical vapor deposition (CVD) chamber;
• a cylinder disposed within said CVD chamber, said cylinder defining a cylinder axis and having an interior surface and an exterior surface, said interior surface defining an inner cylinder diameter, said exterior surface defining an outer cylinder diameter and, said cylinder having a top edge defining an upper plane that is substantially normal to said cylinder axis;
• a peripheral heating element disposed within said cylinder and proximate said interior surface of said cylinder;
• a spindle disposed within said cylinder and extending through peripheral heating element, said spindle having a distal portion that extends above said upper plane of said cylinder;
• a wafer carrier having a top surface that is substantially planar and defining a target plane, said wafer carrier being configured for connection to said distal portion of said spindle for suspension above said peripheral heating element;
• means for reducing scattered radiation that is emitted from a designated portion of said peripheral heating element, said means for reducing scattered radiation being located proximate said peripheral heating element;
• and
• a radiation thermometer arranged to view a target on said target plane that is proximate an axis of reduced scattered radiation, said axis of reduced scattered radiation being coplanar with said target plane and having an origin at said rotation axis extending in a direction of said means for reducing scattered radiation.

A system for limiting stray radiation received by a radiation thermometer, comprising:

• a chemical vapor deposition (CVD) chamber;
• a wafer carrier configured for rotation about a rotation axis, said wafer carrier having a top surface, a bottom surface and a peripheral edge, said top surface defining a target plane substantially orthogonal to said rotation axis;
• a heating element disposed adjacent said bottom surface of said wafer carrier, said heating element being proximate said peripheral edge of said wafer carrier, said heating element including a low heat flux portion configured to operate at a temperature that is at least 300° C. less than any other portion of said heating element when operating at a maximum operating temperature;
• and
• a view port for a radiation thermometer, said viewport arranged for viewing a target that is proximate an axis of reduced scattered radiation, said axis of reduced scattered radiation being coplanar with said target plane and extending from said rotation axis and over said low heat flux portion of said heating element.