Plasma treatment system

#The present invention relates generally to plasma processing, and more particularly to a plasma treatment system configured to perform downstream-type plasma treatments.

#Plasma treatment is commonly applied for modifying the surface properties of workpieces used in applications relating to integrated circuits, electronic packages, and printed circuit boards. Plasma treatment systems are configured to produce a direct plasma from a process gas and expose a surface of a substrate or workpiece with generated active species from the direct plasma to remove surface atoms by physical sputtering, chemically-assisted sputtering, or chemical reactions. The physical or chemical action may be used to condition the surface to improve properties such as adhesion, to selectively remove an extraneous surface layer of a process material, or to clean undesired contaminants from the surface. Plasma treatment is used in electronics packaging, for example, to increase surface activation and/or surface cleanliness for eliminating delamination and bond failures, improving wire bond strength, ensuring void free underfill, removing oxides, enhancing die attach, and improving adhesion for encapsulation.

#Plasma treatment systems may be integrated into in-line and cluster systems or batch processes in which groups of workpieces are processed by successive plasma exposures or processing cycles. Workpieces may be supplied by various methods, include delivery in a magazine, individual delivery by a conveyer transport system, or manual insertion into the process chamber. Plasma treatment systems may also be provided with automated robotic manipulators that coordinate workpiece exchange into and out of the process chamber for plasma processing operations.

#The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and, together with a general description of the invention given above, and the detailed description given below, serve to explain the principles of the invention.

#FIG. 1 is a perspective view of a plasma treatment system in accordance with the principles of the present invention;

#FIG. 2A is a side schematic and partially broken view of the plasma treatment system of FIG. 1;

#The present invention, in accordance with the principles and objectives herein, provides an apparatus and a method for processing a workpiece with a plasma. The present invention provides a plasma treatment system configured to provide a uniformly dense plasma, rapid pump-down and venting cycles, reproducible processing conditions, and simplified material handling. The system advantageously requires a reduced excitation power to initiate and sustain a uniformly dense plasma in the processing space, while employing a control algorithm that minimizes the cycle time required to process each successive workpiece.

#A plasma treatment system 10, in accordance with the principles of the present invention, is illustrated in FIGS. 1, 2A-2C and 3. Referring to FIG. 1, plasma treatment system 10 includes a processing chamber 12, a loading station 20, and an exit station 22, which are situated on a substantially flat and mechanically stable surface 24 atop an instrument cabinet 26. Processing chamber 12 includes a chamber lid 14 hingeably connected to a chamber base 18 by a hinge assembly 16. Chamber lid 14 is selectively positionable between an open position, as shown in FIGS. 1 and 2A, and a closed position, as shown in FIG. 2B. Chamber base 18 and chamber lid 14 are preferably formed of an electrically conductive material suitable for high-vacuum applications, such as an aluminum alloy or a stainless steel.

#Chamber lid 14 includes a domed ceiling 28 and an integral sidewall 30 encircled by a flat rim 32. A viewport opening 38 is provided in ceiling 28 for holding a viewport 34. As best shown in FIG. 2C, viewport 34 is a substantially planar panel attached to chamber lid 14 by a frame 35 and fasteners 36. An O-ring 40 is received within a groove 42 that circumscribes viewport opening 38. Viewport 34 compressively engages O-ring 40 to create a vacuum-tight seal, where the sealing force is supplied collectively by the pressure differential between the interior and exterior of processing chamber 12 and by fasteners 36. Viewport 34 is constructed of a dielectric ceramic, such as quartz, that has a low sputtering coefficient, is gas impermeable, and has a wide transmission range for optical wavelengths. O-ring 40 is preferably formed of an elastomer such as Viton®.