CVD apparatus

A chemical vapor deposition system comprising:

• a susceptor;
• a preheat ring configured to form an opening for receiving the susceptor therein, wherein the susceptor is spaced from the preheat ring to form a substantially circular gap therebetween, the preheat ring having a top surface and a bottom surface and comprising:
• a first portion;
• a second portion selectively coupled to the first portion, wherein each of the first portion and the second portion is independently moveable along a horizontal axis with respect to each other to control a size of the gap;
• and
• a first plurality of elongated grooves formed in the bottom surface of the first portion of the preheat ring, wherein the first plurality of elongated grooves consists of all of the elongated grooves formed in the bottom surface of the first portion of the preheat ring, each of the elongated grooves of the first plurality of elongated grooves having a major axis, the major axis of each elongated groove of the first plurality of elongated grooves being parallel to the major axis of the other elongated grooves of the first plurality of elongated grooves;
• and
• a second plurality of elongated grooves formed in the bottom surface of the second portion of the preheat ring, wherein the second plurality of elongated grooves consists of all of the elongated grooves formed in the bottom surface of the second portion of the preheat ring, each of the elongated grooves of the second plurality of elongated grooves having a major axis, the major axis of each elongated groove of the second plurality of elongated grooves being parallel to the major axis of the other elongated grooves of the second plurality of elongated grooves;
• and
• a ring support coupled to the preheat ring, the ring support including a plurality of posts, each post of the plurality of posts being received in one of the elongated grooves of the first or second plurality of elongated grooves.