GAS DISTRIBUTION PLATE ASSEMBLY FOR PROVIDING LAMINAR GAS FLOW ACROSS THE SURFACE OF A SUBSTRATE

摘要

A baffle plate assembly (12) is provided for distributing gas flow into an adjacent process chamber cavity (20) containing a semiconductor wafer to be processed. The baffle plate assembly (12) comprises a generally planar upper baffle plate (14) fixedly positioned above a generally planar lower baffle plate (16) and covered by a process chamber top wall (17). The top wall (17) and the lower baffle plate form a plenum therebetween, the plenum operating at a higher pressure than the process chamber cavity (20) during operation of the device. At least the lower baffle plate (16) has a pattern of apertures (30) formed therein for permitting gas to pass therethrough and into the wafer process chamber. The upper baffle plate (14) and the lower baffle plate (16) are positioned generally parallel to each other, and the upper baffle plate (14) is smaller than the lower baffle plate (16). Preferably, the lower baffle plate (16) is comprised of low-alloy anodized aluminum, and the upper baffle plate (14) is comprised of sapphire-coated quartz. In a 300 millimeter (mm) embodiment, the apertures (30) in the lower baffle plate (16) are arranged in a pattern such that each aperture (30) is equidistant from any adjacent aperture. The upper baffle plate (14) is provided with slightly larger apertures (28) formed therein in a concentric multiply circular (radial) pattern. The upper baffle plate is also provided with an centrally located impingement plate (62). In a 200 mm embodiment, the apertures (30) in the lower baffle plate (16) are arranged in a concentric multiply circular (radial) pattern, and the upper baffle plate (14) is apertureless. The 200 mm and 300 mm embodiments of the baffle plate assemblies are interchangeable as assembled onto a common process chamber platform. IMAGE