Method and apparatus for chemical mechanical polishing of large size wafer with capability of polishing individual die

Abstract

A novel polisher for chemical mechanical planarization process is described. The polisher design can have many variations. For process development and consumable evaluation, the CMP process can be performed on a single die or a section of the wafer. The size of testing wafer can be as small as 2″ and as large as 18″. Furthermore, several variations can characterize the slurry for their static etch rate, dynamic etch rate, material removal rate, and viscosity in a single experiment. For production level wafer processing, Chemical Mechanical Polishing of all dies on the wafer surface is achieved by using multi-armed polishing heads or a single polishing head with small piece of a pad at the bottom of the head. The within wafer uniformity can be easily controlled and the equipment can be easily scaled up or down. This inventive design may translate to significant cost reduction for wafer processing at production level as well as evaluation of consumables at research and development level.

1 . A method of chemical mechanical polishing of a surface of a substrate to remove selected portions thereof comprising:
 (i) maintaining at least a portion of the surface of the substrate in sliding fractional contact with the polishing pad until the selected portions of the surface of the substrate are removed;   (ii) polishing one area on a blanket/patterned wafer, containing one or more dies, using a single polishing head with a small piece of commercial CMP pad or a pad under evaluation; and   (iii) polishing a patterned wafer using multi-arm polishing head with each polishing arm corresponding to a die on the patterned wafer   
       wherein the die(s) on the Patterned wafer desired to be polished is processed and the remaining dies are protected by a cover or a mask. 
     
     
         2 . (canceled) 
     
     
         3 . The method of  claim 1 , wherein only a portion of the surface of the substrate is polished by a single polish head or multi-arm polish head with multiple pads while the rest area of the surface of the substrate to be polished is protected. 
     
     
         4 . An apparatus for chemical mechanical polishing of a surface of a substrate to remove selected portions thereof comprising:
 (i) a fixed platen to hold the wafer to be polished, the wafer holder is changeable, and the size of the holder adjustable to fit different size of the wafer;   (ii) a cam with an offset with the motor axle to make orbital motion of the polishing pad and achieves the same relative velocity between each point on the pad and the area to be polished;   (iii) a device for providing an oscillatory motion on the surface of a single die;   (iv) a disk to hold the multi-arm polish head system;   (v) a slurry delivery system in which the slurry can be supplied to each individual die on the patterned wafer separately;   (vi) a two-motor system, one motor rotates the disk that holds the second motor and the second motor rotates the pad in a same rotation speed and the same direction as that of the first motor and thus the same relative velocity between each point on the pad and the area to be polished is achieved;   (vii) a two-lever adjustment system to control the position of the polish head and the wafer whereby all the dies on the patterned wafer can be polished;   (viii) adjustable legs for tilting the whole apparatus;   (ix) a slurry collection system to collect used slurry; and   (x) a replaceable pad conditioning disk.   
     
     
         5 . The apparatus of  claim 4 , wherein the tubes of the slurry delivery system are distributed in parallel. 
     
     
         6 . A device for the evaluation of the performance and characteristics of a slurry comprising of a slurry chamber, a rotary wafer carrier that is vertically placed and fixed on lateral movement, a rotary pad carrier that is movable along its lateral axis, a sensor which measures the film thickness change in-situ, and a sensor which measures the resistance exerted on to the rotary movement of the pad carrier. 
     
     
         7 . The device of  claim 6 , lateral and rotary movements for the pad and wafer carriers are accomplished by DC motors. 
     
     
         8 . The device of  claim 6 , lateral and rotary movements of the pad carrier are accomplished by the use of a magnetic levitation system. 
     
     
         9 . The device of  claim 6 , the film thickness change is measured by 14-point probe or Eddy current system for metal films. 
     
     
         10 . The device of  claim 9 , wherein the film is a dielectric film and the measurement is made by an optical sensor. 
     
     
         11 . The device of  claim 10 , wherein an acoustic sensor for measuring the film thickness change for metal and non-metal is simultaneously used. 
     
     
         12 . A polisher that utilizes polishing tape for IC wafer processing comprising of a slurry delivery system, a tape management system, a guiding system for the tape, and optionally a system for tape cleaning, conditioning, and re-use. 
     
     
         13 . The polisher of  claim 12 , the tape can be made with natural, process natural materials or synthetic materials. 
     
     
         14 . The polisher of  claim 12 , wherein the tape management system is selected from the group consisting of a controller of tape tension, a controller of tape movement, a tape cleaner, a tape conditioner, an embosser of patterns before the tape reaches the wafer, a flipping mechanism that allows the use of either side of the tape and combinations thereof. 
     
     
         15 . The polisher of  claim 12 , wherein the tape guiding system may include a solid roller or a block that controls the distance between the tape and the wafer.