Method and apparatus for determining shear force between the wafer head and polishing pad in chemical mechanical polishing

Abstract

A method for (a) determining the shear force between a wafer head and a polishing pad in a polishing tool using a CMP polishing tool with a plate above the wafer head which hangs or rests on the plate. The plate is connected to the CMP polishing tool by (b) low friction motion means (c). A load cell sensor is fixed to the framework of the polishing tool or another immovable structure. (d) The load cell determines the force from the leading edge of the plate when the wafer head is in contact with the polishing pad. (e) Signals from the load cell sensor reporting the shear force. A CMP polishing tool which includes elements corresponding to each of points (a)-(e) in the above method.

1 . A method for determining the shear force between the wafer head and the polishing pad in a polishing tool wherein the said determination is accomplished by means of a CMP polishing tool with a plate positioned above the wafer head and from which the wafer head and its supporting apparatus hang, or upon which they rest, said plate connected to the framework of the said CMP polishing tool by low friction motion means capable of sliding in a direction perpendicular to the line between the center of the polishing pad and the center of the wafer head, and a load cell sensor firmly fixed to the framework of the polishing tool or other immovable structure and positioned to contact and determine the force from the leading edge of said plate when the polishing tool is in operation and the wafer head is in contact with the polishing pad, the signals thus obtained reporting the shear force. 
   
   
       2 . A method according to  claim 1  wherein the load cells are attached to a data processing means that receives and analyzes the data and reports the shear force. 
   
   
       3 . A method according to  claim 1  wherein load cells are attached to and support the bottom of the module of the polishing pad of the CMP polishing tool to determine the down force, and the down force and shear force thus obtained may be used to calculate the coefficient of friction between the wafer head and the polishing pad. 
   
   
       4 . A method according to  claim 3  wherein the number of load cells measuring the down force is 4. 
   
   
       5 . A method according to  claim 3  or  4  wherein the load cells are attached to a data processing means that receives and analyzes the data and reports the respective components of and the total shear force and reports and calculates the coefficient of friction between the wafer and the polishing pad. 
   
   
       6 . A method according to  claim 1  wherein the said low friction motion means are rails. 
   
   
       7 . A method according to  claim 1  wherein the said low friction motion means are block and pillow sliders. 
   
   
       8 . A method for determining two perpendicular force components of shear force between a wafer head and the polishing pad in a polishing tool wherein the said determination is accomplished by means of a CMP polishing tool with two plates positioned above the wafer head and from which the wafer head and its supporting apparatus hang, or upon which they rest, one plate connected to the framework of the polishing tool by low friction motion means, the other said plate connected to the first said plate by low friction motion means allowing the said other plate to slide in a direction perpendicular to the motion of the first said plate, and load cell sensors firmly fixed to the framework of the polishing tool or other immovable structure and positioned to contact and determine the force from the leading edge of each of said plates when the polishing tool is in operation and the wafer head is in contact with the polishing pad, the signals from said load cells reporting the perpendicular components of shear force. 
   
   
       9 . A method according to  claim 8  wherein the load cells are attached to a data processing means that receives and analyzes the data and reports the respective perpendicular components of the total shear force. 
   
   
       10 . A method according to  claim 8  wherein load cells are attached to and support the bottom of the module of the polishing pad of the CMP polishing tool to determine the down force, and the down force and shear force thus obtained may be used to calculate the coefficient of friction between the wafer head and the polishing pad. 
   
   
       11 . A method according to  claim 10  wherein the number of load cells used to determine the down force is 4. 
   
   
       12 . A method according to  claim 10  or  11  wherein the load cells are attached to a data processing means that receives and analyzes the data and reports the respective components of and the total shear force and reports and calculates the coefficient of friction between the wafer and the polishing pad. 
   
   
       13 . A method according to  claim 8  wherein the said low friction motion means are rails. 
   
   
       14 . A method according to  claim 8  wherein the said low friction motion means are block and pillow sliders. 
   
   
       15 . A CMP polishing tool that determines and reports the shear force between the wafer head and the polishing pad wherein the said determination is accomplished by means of a plate positioned above the wafer head and from which the wafer head and its supporting apparatus hang, or upon which they rest, said plate connected to the framework of the CMP polishing tool by low friction motion means capable of sliding in a direction perpendicular to the line between the center of the polishing pad and the center of the wafer head, and a load cell sensor firmly fixed to the framework of the CMP polishing tool or other immovable structure and positioned to contact and determine the force from the leading edge of said plate when the CMP polishing tool is in operation and the wafer head is in contact with the polishing pad, the signals thus obtained reporting the shear force. 
   
   
       16 . A CMP polishing tool according to  claim 15  wherein the load cells are attached to a data processing means that receives and analyzes the data and reports the shear force. 
   
   
       17 . A CMP polishing tool according to  claim 15  wherein load cells are attached to and support the bottom of the module of the polishing pad of the CMP polishing tool to determine the down force, and the down force and shear force thus obtained may be used to calculate the coefficient of friction between the wafer head and the polishing pad. 
   
   
       18 . A CMP polishing tool according to  claim 17  wherein the number of load cells measuring the down force is 4. 
   
   
       19 . A CMP polishing tool according to  claim 17  or  18  wherein the load cells are attached to a data processing means that receives and analyzes the data and reports the respective components of and the total shear force and reports and calculates the coefficient of friction between the wafer and the polishing pad. 
   
   
       20 . A CMP polishing tool according to  claim 15  wherein the said low friction motion means are rails. 
   
   
       21 . A CMP polishing tool according to  claim 15  wherein the said low friction motion means are block and pillow sliders. 
   
   
       22 . A CMP polishing tool that determines and reports two perpendicular force components of shear force between a wafer head and the polishing pad in a polishing tool wherein the said determination is accomplished by means of two plates positioned above the wafer head and from which the wafer head and its supporting apparatus hang, or upon which they rest, one plate connected to the framework of the CMP polishing tool by low friction motion means, the other said plate connected to the first said plate by low friction motion means allowing the said other plate to slide in a direction perpendicular to the motion of the first said plate, and load cell sensors firmly fixed to the framework of the CMP polishing tool or other immovable structure and positioned to contact and determine the force from the leading edge of each of said plates when the polishing tool is in operation and the wafer head is in contact with the CMP polishing pad, and reports the said perpendicular force components as signals. 
   
   
       23 . A CMP polishing tool according to  claim 22  wherein the load cells are attached to a data processing means that receives and analyzes the data and reports the respective perpendicular components of the total shear force. 
   
   
       24 . A CMP polishing tool according to  claim 22  wherein load cells are attached to and support the bottom of the module of the polishing pad of the CMP polishing tool to determine the down force, and the down force and shear force thus obtained may be used to calculate the coefficient of friction between the wafer head and the polishing pad. 
   
   
       25 . A CMP polishing tool according to  claim 24  wherein the number of load cells measuring the down force is 4. 
   
   
       26 . A CMP polishing tool according to  claim 24  or  25  wherein the load cells are attached to a data processing means that receives and analyzes the data and reports the respective components of and the total shear force and reports and calculates the vector sum of the said two perpendicular components and the COF between the wafer and the polishing pad. 
   
   
       27 . A CMP polishing tool according to  claim 22  wherein the said low friction motion means are rails. 
   
   
       28 . A CMP polishing tool according to  claim 22  wherein the said low friction motion means are block and pillow sliders. 
   
   
       29 . A method for determining two perpendicular force components of shear force between a wafer head and the polishing pad in a polishing tool wherein the said determination is accomplished by means of a CMP polishing tool two plates positioned above the wafer head and from which the wafer head and its supporting apparatus hang, or upon which they rest, one plate connected to the framework of the said CMP polishing tool by low friction rails, the other said plate connected to the first said plate by low friction rails allowing the said other plate to slide in a direction perpendicular to the motion of the first said plate, load cell sensors firmly fixed to the framework of the CMP polishing tool or other immovable structure and positioned to contact and determine the force from the leading edge of each of said plates when the polishing tool is in operation and the wafer head is in contact with the polishing pad, the signals of said load cells reporting the components of shear force,  4  load cells are attached to and support the bottom of the module of the polishing pad of the CMP polishing tool to determine the down force, which generates a signal from the said load cells at the bottom of the CMP polishing tool and the down force and perpendicular shear force signals are reported and the signals from the load cells are delivered to a data processing means that receives and analyzes the data and reports the respective components of and the total shear force and calculates and reports the coefficient of friction between the wafer and the polishing pad. 
   
   
       30 . A CMP polishing tool that determines two perpendicular force components of shear force between a wafer head and the polishing pad in a polishing tool wherein the said determination is accomplished by means two plates positioned above the wafer head and from which the wafer head and its supporting apparatus hang, or upon which they rest, one plate connected to the framework of the said CMP polishing tool by low friction rails, the other said plate connected to the first said plate by low friction rails allowing the said other plate to slide in a direction perpendicular to the motion of the first said plate, load cell sensors firmly fixed to the framework of the CMP polishing tool or other immovable structure and positioned to contact and determine the force from the leading edge of each of said plates when the polishing tool is in operation and the wafer head is in contact with the polishing pad, the signals of said load cells reporting the components of shear force,  4  load cells are attached to and support the bottom of the module of the polishing pad of the CMP polishing tool to determine the down force, which generates a signal from the said load cells at the bottom of the CMP polishing tool and the down force and perpendicular shear force signals are reported and the signals from the load cells are delivered to a data processing means that receives and analyzes the data and reports the respective components of and the total shear force and calculates and reports the coefficient of friction between the wafer and the polishing pad