Wafer processing with carrier extension

Abstract

Apparatus for treating wafers using a wafer carrier rotated about an axis is provided with a ring which surrounds the wafer carrier during operation. Treatment gasses directed onto a top surface of the carrier flow outwardly away from the axis over the carrier and over the ring, and pass downstream outside of the ring. The outwardly flowing gasses form a boundary over the carrier and ring. The ring helps to maintain a boundary layer of substantially uniform thickness over the carrier, which promotes uniform treatment of the wafers.

We claim: 
     
         1 . A wafer carrier comprising a body having a circular top surface, a peripheral surface bounding the top surface and a fitting adapted to engage a spindle of a wafer processing reactor so that the top surface and peripheral surface are concentric with the spindle, the body further defining a plurality of pockets each adapted to hold a wafer, the pockets including outer pockets adapted to hold wafers so that portions of the wafers lie within about 5 mm of the peripheral surface. 
     
     
         2 . A wafer carrier as claimed in  claim 2  wherein the top surface has a diameter of about 465 mm and the pockets include at least six pockets, each adapted to hold a wafer having a diameter of about 6 inches.