| 摘要 |
An apparatus and method to position a wafer onto a wafer holder and to maintain a uniform wafer temperature is disclosed. The wafer holder or susceptor comprises a recess or pocket whose surface includes a grid containing a plurality of grid grooves that separate protrusions. A plurality of gas passages is provided in the susceptor to enable an upward flow of gas toward the bottom surface of the substrate. During drop-off of the substrate, a cushion gas flow is provided to substantially slow the rate of descent of the substrate onto the susceptor and to gradually heat the substrate before it makes contact with the susceptor. Optionally, a trickle gas flow may be provided through the aforementioned passages during processing of the substrate to prevent deposition of reactant gases onto the bottom surface of the substrate. A liftoff gas flow may then be provided through the passages to help lift the substrate off of the susceptor after processing is completed and thus aid in removing the substrate from the process chamber. These features help to achieve temperature uniformity and thus quality of deposited films onto the substrate.
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