Method of manufacturing semiconductor device, plasma processing apparatus and plasma processing method

Abstract

In a method of manufacturing a semiconductor device by dividing a semiconductor wafer 6 , on which a plurality of semiconductor elements are formed, into individual pieces of the semiconductor elements, after thickness of a reverse face of a circuit formation face 6 a is reduced by machining, a mask to determine cutting lines 31 b is formed by a resist film 31 a , and the semiconductor wafer 6 is divided into individual pieces of semiconductor elements 6 c by conducting plasma etching on portions of the cutting lines 31 b when plasma is exposed from the mask side, and then the resist film 31 a is removed by plasma, and further a micro-crack layer 6 b generated on the machined face is removed by plasma etching. A series of the above plasma processing is executed by the same plasma processing apparatus.

1 . A plasma processing apparatus of executing plasma dicing, removing a mask and removing micro-cracks by carrying out plasma processing on a semiconductor wafer in which a protective sheet is attached on the first face on which semiconductor elements are formed and a mask for determining cutting lines to divide the semiconductor wafer into individual pieces of the semiconductor elements is formed on the second face opposite to the first face, the plasma processing apparatus comprising: 
 a processing chamber;    a first electrode having a plane with which the protective sheet tightly comes into contact in the processing chamber;    a second electrode opposed to the first electrode in the processing chamber;    a holding means for holding the semiconductor wafer by the first electrode under the condition that the protective sheet tightly comes into contact with the plane;    a pressure reducing means for reducing pressure to a predetermined value in the processing chamber;    a plasma generating gas supplying means for selectively supplying a plurality of types of plasma generating gases into the processing chamber;    a pressure controlling means for controlling pressure in the processing chamber when plasma generating gas is supplied;    a high frequency electric power supply section for supplying a high frequency voltage upon the first electrode so as to transfer the plasma generating gas, which has been supplied into the processing chamber, into a plasma state; and    an electrode distance changing means for changing a distance between the first and the second electrode.    
     
     
         2 . A plasma processing apparatus according to  claim 1 , wherein the electrode distance changing means makes an electrode distance between the first and the second electrode in the case of removing the mask be larger than an electrode distance in the cases of plasma dicing and removing micro-cracks.  
     
     
         3 . A plasma processing apparatus according to  claim 1 , wherein the holding means includes a vacuum attracting means for attracting the protective sheet by vacuum via a plurality of suction holes which are open to the plane.  
     
     
         4 . A plasma processing apparatus according to  claim 1 , wherein the protective sheet includes an insulating layer, the plane is made of a conductive material which is the same as the material of the first electrode, and 
 the holding means includes a DC voltage supplying means for electrostatically attracting the semiconductor wafer by utilizing the Coulomb's force acting between the semiconductor wafer and the plane, which are separate from each other by the protective sheet, when DC voltage is supplied upon the electrode.    
     
     
         5 . A plasma processing apparatus according to  claim 1 , wherein the plasma generating gas supplying means supplies mixed gas containing fluorine gas into the processing chamber in the steps of the plasma dicing and the micro-crack removing.  
     
     
         6 . A plasma processing apparatus according to  claim 1 , wherein the plasma generating gas supplying means supplies the same mixed gas containing fluorine gas into the processing chamber in the steps of the plasma dicing and the micro-crack removing.  
     
     
         7 . A plasma processing apparatus according to  claim 1 , wherein the plasma generating gas supplying means supplies gas containing at least oxygen into the processing chamber in the step of the mask removing.  
     
     
         8 . A plasma processing apparatus according to  claim 1 , further comprising a cooling means for cooling the first electrode.