Ion beam etching system

Abstract

The disclosed embodiments relate to methods and apparatus for removing material from a substrate. In various implementations, conductive material is removed from a sidewall of a previously etched feature such as a trench, hole or pillar on a semiconductor substrate. In practicing the techniques herein, a substrate is provided in a reaction chamber that is divided into an upper plasma generation chamber and a lower processing chamber by a corrugated ion extractor plate with apertures therethrough. The extractor plate is corrugated such that the plasma sheath follows the shape of the extractor plate, such that ions enter the lower processing chamber at an angle relative to the substrate. As such, during processing, ions are able to penetrate into previously etched features and strike the substrate on the sidewalls of such features. Through this mechanism, the material on the sidewalls of the features may be removed.

1 . (canceled) 
     
     
         2 . An ion extractor plate for an etching reactor, the ion extractor plate comprising:
 a plate, wherein at least a portion of the plate is corrugated; and   a plurality of apertures in the plate, each aperture having a center and an axis extending therethrough, wherein the axis extending through the center of a corresponding aperture is oriented normal to a local surface of the ion extractor plate where the corresponding aperture is positioned, and wherein the apertures are configured to permit the passage of ions therethrough when the plate is exposed to a plasma in the etching reactor.   
     
     
         3 . The ion extractor plate of  claim 2 , wherein a principal dimension of the apertures is between about 0.5-5 mm, the principal dimension being measured in a direction parallel to the local surface of the ion extractor plate where the corresponding aperture is positioned. 
     
     
         4 . The ion extractor plate of  claim 2 , wherein at least some of the apertures are cone-shaped, such that when considering a single cone-shaped aperture, an aperture open area on a first side of the ion extractor plate is smaller than an aperture open area on an opposite side of the ion extractor plate. 
     
     
         5 . The ion extractor plate of  claim 2 , wherein some or all of the apertures are circularly shaped. 
     
     
         6 . The ion extractor plate of  claim 2 , wherein some or all of the apertures have a non-circular shape. 
     
     
         7 . The ion extractor plate of  claim 6 , wherein some or all of the apertures have an oval shape, a slot shape, a polygon shape, a C-shape, or a T-shape. 
     
     
         8 . The ion extractor plate of  claim 2 , wherein the ion extractor plate has a thickness that is at least about 1 mm and less than about 25 mm. 
     
     
         9 . The ion extractor plate of  claim 2 , wherein the ion extractor plate has a total open area between about 1-50%. 
     
     
         10 . The ion extractor plate of  claim 2 , wherein the portion of the plate that is corrugated comprises cone-shaped features, each cone-shaped feature comprising one or more of the apertures. 
     
     
         11 . The ion extractor plate of  claim 10 , wherein the cone-shaped features do not have a uniform height and/or diameter. 
     
     
         12 . The ion extractor plate of  claim 10 , wherein a number of apertures per cone-shaped feature is not uniform. 
     
     
         13 . The ion extractor plate of  claim 2 , wherein the plate comprises a plurality of corrugated segments, the corrugated segments including at least two distinct segment types, wherein each corrugated segment comprises a single type of corrugation feature. 
     
     
         14 . The ion extractor plate of  claim 13 , wherein a first segment type is configured to direct ions that travel through apertures in the first segment type during etching in a direction radially offset from a position of the corresponding apertures, and wherein a second segment type is configured to direct ions that travel through apertures in the second segment type during etching in a direction that is azimuthally offset from a position of the corresponding apertures. 
     
     
         15 . The ion extractor plate of  claim 13 , wherein the corrugated segments are pie-shaped or rectangle-shaped. 
     
     
         16 . The ion extractor plate of  claim 2 , wherein the plate comprises two or more distinct types of corrugation features. 
     
     
         17 . The ion extractor plate of  claim 2 , wherein the portion of the plate that is corrugated accounts for at least about 50% of a surface area of the plate. 
     
     
         18 . The ion extractor plate of  claim 2 , wherein the portion of the plate that is corrugated comprises corrugation features, the corrugation features each having a corresponding angle of corrugation, wherein the angles of corrugation are not uniform. 
     
     
         19 . The ion extractor plate of  claim 18 , wherein a difference between a smallest angle of corrugation and a largest angle of corrugation is at least about 10°. 
     
     
         20 . The ion extractor plate of  claim 2 , further comprising embedded cooling channels and/or an embedded heating element. 
     
     
         21 . The ion extractor plate of  claim 2 , wherein the portion of the plate that is corrugated comprises a plurality of corrugation peaks, wherein a distance between adjacent corrugation peaks is at least about 2 mm.