Apparatus and method for etching a wafer edge

Abstract

An apparatus and method for etching a portion of a wafer include a mount for holding a wafer having an edge, a front surface, a back surface and an axis perpendicular to the front and back surfaces. A frame is used to deliver an etchant to the wafer edge while the wafer is held with the wafer edge at a distance from the frame. A nonreactive fluid flow may be provided and directed along the front and back surfaces of the wafer edge to drive the etchant away from the front and back surfaces. The frame can be configured either to deliver the etchant in liquid form or to deliver the etchant in vapor form. The frame can include a plenum for directing the etchant in vapor form to the wafer edge within a receiving area of the plenum, or the frame can include a roller having a groove for receiving the wafer edge and for drawing the etchant in liquid form to the wafer edge.

1 . An apparatus for etching a portion of a wafer, the wafer including an edge, a front surface, a back surface and a central axis perpendicular to the front and back surfaces, the apparatus comprising:
 a transport mechanism configured to deliver etchant to the edge of the wafer, the transport mechanism including a frame configured to bring the etchant to a location where the etchant contacts the edge of the wafer;   a mount adjacent the transport mechanism for holding the wafer in a vertical orientation with the central axis substantially horizontal, the mount configured to position the wafer edge in the location where the etchant contacts the edge of the wafer with the wafer edge spaced apart from the frame, the mount including a drive configured to rotate the wafer about the central axis; and   a fluid source adjacent the transport mechanism, the fluid source configured to direct a non-reactive fluid flow along the front and back surfaces of the wafer toward the edge so as to drive the etchant away from the front and back surfaces.   
     
     
         2 . The apparatus recited in  claim 1  wherein the frame of the transport mechanism includes a plenum configured to draw the etchant as a vapor into contact with the wafer edge. 
     
     
         3 . The apparatus recited in  claim 2  wherein the frame includes a vacuum channel adjacent the wafer edge. 
     
     
         4 . The apparatus recited in  claim 3  wherein the frame includes a slit adjacent the wafer edge and in fluid communication with the vacuum channel, wherein the etchant vapor and the nonreactive fluid flow are drawn through the slit and into the vacuum channel. 
     
     
         5 . The apparatus of  claim 1  wherein the transport mechanism includes an etchant roller having a groove configured to draw the etchant in a liquid form into the location where the etchant contacts the wafer edge, and wherein the frame of the transport mechanism includes the groove of the etchant roller. 
     
     
         6 . The apparatus of  claim 1  further comprising a reservoir for holding a supply of the etchant in a liquid form, the reservoir disposed adjacent the transport mechanism. 
     
     
         7 . The apparatus recited in  claim 1  wherein the mount is configured to accommodate multiple wafers for simultaneous application of etchant. 
     
     
         8 . The apparatus recited in  claim 1  wherein the mount includes a pair of wafer rotation rollers, the rollers located on opposite sides of the transport mechanism. 
     
     
         9 . An apparatus for etching a portion of a wafer, the wafer including an edge, a front surface, a back surface and a central axis perpendicular to the front and back surfaces, the apparatus comprising:
 a mount for holding the wafer, the mount including a drive, the mount and drive configured to support and rotate the wafer about the axis;   a plenum adjacent the mount and configured to deliver vapor etchant to the edge of the wafer and direct the etchant away from the wafer surfaces.   
     
     
         10 . The apparatus recited in  claim 9  wherein the plenum is defined by an upper portion and a lower portion and a slit disposed between the portions, wherein the mount is configured to hold the wafer with the wafer edge disposed in a vicinity of the slit. 
     
     
         11 . The apparatus of  claim 10  wherein at least one of the upper portion and the lower portion include a vacuum channel in fluid communication with the slit. 
     
     
         12 . The apparatus recited in  claim 9  wherein the plenum includes an inner baffle defining a fluid path for the etchant, the fluid path configured to receive the wafer edge therein. 
     
     
         13 . The apparatus recited in  claim 9  further comprising a fluid source adjacent the plenum, the fluid source configured to direct a nonreactive fluid flow into the plenum and along the front and back surfaces of the wafer in a direction toward the wafer edge. 
     
     
         14 . The apparatus recited in  claim 9  further comprising a reservoir for holding a supply of the etchant in a liquid form, the reservoir disposed adjacent the plenum. 
     
     
         15 . The apparatus recited in  claim 14  further comprising a venturi array configured to draw the etchant in vapor form from the reservoir into the plenum. 
     
     
         16 . The apparatus recited in  claim 15  wherein the venturi array provides an exhaust, and wherein the exhaust from the venturi is configured to recirculate the etchant into the plenum. 
     
     
         17 . The apparatus of  claim 9  wherein the mount includes a pair of wafer rotation rollers located on opposite sides of the plenum. 
     
     
         18 . An apparatus for etching a portion of a wafer, the wafer including an edge, a front surface, a back surface, a width between the front and back surfaces, and a central axis perpendicular to the front and back surfaces, the apparatus comprising:
 a frame including a groove defined by a pair of opposed spaced apart walls, the groove configured to receive the wafer and having a width between the walls that is greater than the width of the wafer, and the groove configured to deliver liquid etchant within the groove to the wafer edge; and   a mount for holding the wafer in a vertical orientation with the central axis substantially horizontal, the mount configured to position the wafer edge within the groove, the mount including a drive configured to rotate the wafer about the central axis.   
     
     
         19 . The apparatus recited in  claim 18  wherein the groove is defined on an etchant roller, the etchant roller being configured to deliver etchant to wafer within the groove when the roller is rotated. 
     
     
         20 . The apparatus recited in  claim 18  further comprising a reservoir for holding a supply of the liquid etchant at a depth so as to form a liquid surface, wherein the groove is positioned with a portion that is located above the liquid surface, and wherein the etchant roller is configured to deliver the etchant to the wafer edge in the portion of the groove located above the liquid surface. 
     
     
         21 . The apparatus recited in  claim 18  further comprising a fluid source adjacent the frame, the fluid source configured to direct a nonreactive fluid flow along the front and back surfaces of the wafer in a direction toward the wafer edge so as to drive the etchant away from the front and back surfaces. 
     
     
         22 . The apparatus recited in  claim 21  wherein the fluid source includes a drying comb including at least a first and a second nozzle configured to direct the nonreactive fluid flow along the front and back surfaces of the wafer. 
     
     
         23 . The apparatus recited in  claim 18  wherein the mount includes a pair of wafer rotation rollers, the rollers located on opposite sides of the frame. 
     
     
         24 . A method for etching at least a portion of a wafer, the method comprising:
 providing a wafer including an edge, a front surface, a back surface, and a central axis perpendicular to the front and back surfaces;   providing a frame for delivering etchant to the edge of the wafer, the frame defining an receiving area for receiving the wafer edge;   holding the wafer in a vertical orientation with the central axis substantially horizontal and with the wafer edge disposed in the receiving area of the frame with a gap between the wafer edge and the frame;   rotating the wafer about the central axis with the wafer edge moving within the frame;   delivering etchant in the frame to the wafer edge; and   directing a nonreactive fluid flow along the front and back surfaces of the wafer so as to drive the etchant away from the front and back surfaces.   
     
     
         25 . The method recited in  claim 24  wherein the etchant is delivered in the frame to the edge of the wafer in vapor form. 
     
     
         26 . The method recited in  claim 24  wherein the etchant is delivered in the frame to the edge of the wafer in liquid form. 
     
     
         27 . The method of  claim 26  wherein the delivering the etchant to the wafer edge includes converting the etchant from a liquid form into the vapor form. 
     
     
         28 . The method recited in  claim 24 , wherein the etchant includes hydrofluoric acid. 
     
     
         29 . The method recited in  claim 24 , wherein the nonreactive fluid flow includes nitrogen. 
     
     
         30 . The method recited in  claim 24 , wherein the frame includes a roller having a groove forming the receiving area, and wherein delivering the etchant in the frame to the wafer edge includes rotating the roller so as to draw the etchant in liquid form toward the wafer edge. 
     
     
         31 . The method recited in  claim 24 , wherein the frame includes a plenum and wherein delivering the etchant in the frame to the wafer edge includes generating a vapor circulation through the plenum so as to draw the etchant into the plenum in vapor form.