Method For the Material-Removing Machining of Very Thin Work Pieces in a Double Sided Grinding Machine

Abstract

The invention relates to a method for machining by grinding or polishing of very thin work pieces which are releasably fastened each to thin carriers. The work pieces are arranged together with the carriers in the recesses of at least on rotor disc of a double sided processing machine and are moved along cycloid paths between the working surfaces of the double sided processing machine. Thereby, the removal rate on the working surfaces of the double sided processing machine is either the same or the removal rate on a working surface is substantially less than the one on the opposing working surface, or on one of the working surfaces no material removal takes place. In one embodiment two work pieces are on carrier, that is, releasably fastened on upper and lower side.

1 . Method for the material-removing machining, in particular for machining by grinding or polishing, of very thin work pieces ( 38 ) which are releasably fastened with one of their surfaces in each case to a corresponding surface of similarly very thin carriers ( 28 ), the method comprising the steps:
 a double sided processing machine ( 10 ) is provided which has an upper working disc ( 16 ) with an upper working surface and a lower working disc ( 20 ) with a lower working surface, the working surfaces forming a working gap therebetween, in which at least one rotor disc ( 22 ) comprising recesses ( 23 ) is arranged,   the work pieces ( 38 ) are arranged together with the carriers ( 28 ) in the recesses ( 23 ) of the at least one rotor disc ( 22 ),   at least one of the working discs ( 16 ,  20 ) is driven rotatably, the at least one rotor disc ( 22 ) also being set in rotation by means of a roller device, whereby the carriers ( 28 ) received in the rotor disc ( 22 ) move with the work pieces ( 38 ) along cycloid paths between the working surfaces, and one of the working surfaces coming into contact with the respective free surfaces of the carriers ( 28 ) and one of the working surfaces coming into contact with the respective free surfaces of the work pieces ( 38 ),   the free surfaces of the work pieces ( 38 ) are machined in a material-removing manner by the working surface associated therewith, whilst by the working surface associated with the free surfaces of the carriers ( 28 ), either no material is removed or a removal rate of the free surfaces of the carriers ( 28 ) is substantially less than a removal rate of the free surfaces of the work pieces ( 38 ) or the removal rate of the free surfaces of the carriers ( 28 ) is the same as the removal rate of the free surfaces of the work pieces ( 38 ).   
     
     
         2 . Method according to  claim 1 , wherein different removal rates of the free surfaces of the carriers ( 28 ), on the one hand, and the free surfaces of the work pieces ( 38 ), on the other hand, are produced by the upper working surface and the lower working surface having different working coatings. 
     
     
         3 . Method according to  claim 1 , wherein characterized in that the material-removing machining is abrasive machining, the working surface associated with the surfaces of the work pieces ( 38 ) being provided with an abrasive coating and the working surface associated with the surfaces of the carriers ( 28 ) being provided with a polishing coating. 
     
     
         4 . Method according to  claim 3 , wherein the machining with the polishing coating takes place without a polishing means. 
     
     
         5 . Method for the material-removing machining, in particular for machining by grinding or polishing, of very thin work pieces ( 38 ) which are releasably fastened in pairs with one of their surfaces to corresponding opposing surfaces of similarly very thin carriers ( 28 ), the method comprising the steps:
 a double sided processing machine ( 10 ) is provided which has an upper working disc ( 16 ) with an upper working surface and a lower working disc ( 20 ) with a lower working surface, the working surfaces forming a working gap therebetween, in which at least one rotor disc ( 22 ) comprising recesses ( 23 ) is arranged,   the work pieces ( 38 ) are arranged together with the carriers ( 28 ) in the recesses ( 23 ) of the at least one rotor disc ( 22 ),   at least one of the working discs ( 16 ,  20 ) is driven rotatably, the at least one rotor disc ( 22 ) being also set in rotation by means of a roller device, whereby the carriers ( 28 ) received in the rotor disc ( 22 ) move with the work pieces ( 38 ) along cycloid paths between the working surfaces, and one of the working surfaces coming into contact with the respective free surfaces of the work pieces fastened to one side of the carriers ( 28 ) and one of the working surfaces coming into contact with the respective free surfaces of the work pieces ( 38 ) fastened to the opposing side of the carriers ( 28 ),   the free surfaces of the work pieces releasably fastened to the opposing sides of the carriers ( 28 ) are respectively machined in a material-removing manner by the working surface associated therewith.   
     
     
         6 . Method according to  claim 1  wherein before the machining process, the work pieces ( 38 ) have a smaller thickness than the carriers ( 28 ). 
     
     
         7 . Method according to  claim 1  wherein after the machining process, the work pieces ( 38 ) have a thickness of less than 100 μm, preferably less than 50 μm, further preferably less than 20 μm. 
     
     
         8 . Method according to  claim 1  wherein the carriers ( 38 ) have a thickness ranging between 0.5 mm to 2 mm, preferably ranging between 0.7 mm to 1.0 mm. 
     
     
         9 . Method according to  claim 1  wherein the carriers ( 38 ) and the work pieces ( 28 ) have a cylindrical shape and the carriers ( 38 ) have a larger diameter than the work pieces ( 28 ). 
     
     
         10 . Method according to  claim 1  wherein, the work pieces ( 38 ) are fastened to the carriers ( 28 ) by an adhesive connection ( 34 ), in particular by wax, an adhesive or an adhesive film. 
     
     
         11 . Method according to  claim 10 , wherein the adhesive connection is releasable thermally, chemically, by etching or by UV radiation. 
     
     
         12 . Method according to  claim 1  wherein the work pieces ( 38 ) are fastened to the carriers ( 28 ) by electrostatic charging. 
     
     
         13 . Method according to  claim 1  wherein the workpiece ( 38 ) is a semiconductor wafer. 
     
     
         14 . Method according to  claim 1  wherein the carrier ( 28 ) is a semiconductor wafer. 
     
     
         15 . Method according to  claim 1  wherein the carrier ( 28 ) consists of a glass material, a ceramic material or a plastics material. 
     
     
         16 . Method according to  claim 1  wherein the thickness of the work pieces ( 38 ) is measured during the machining thereof in the processing machine by means of an optical measuring method, in particular an interferometric measuring method. 
     
     
         17 . Method according to  claim 1  wherein the thickness of the work pieces ( 38 ) is measured during the machining thereof in the processing machine by means of at least one eddy-current sensor or by means of at least one ultrasound sensor.