Methods for controlling the pressures of adjustable pressure zones of a work piece carrier during chemical mechanical planarization

A method for producing a target thickness profile of a material layer on a first surface of a work piece utilizing a CMP apparatus having a work piece carrier with a number Zf of pressure adjustable zones, wherein each zone is configured to exert a pressure against a second surface of the work piece during a CMP process, the method comprising the steps of:

• for each zone, determining a first thickness Tz,n−1 of the material layer, where z is an integer between 1 and Zf, n is an integer between 1 and N, and N is the total number of times thickness measurements are assessed;
• calculating a first average thickness τn−1 of the material layer across the work piece;
• for each zone, removing a first portion of the material layer, wherein each of said zones is configured to exert a first pressure Pz,n against the second surface of the work piece;
• for each zone, determining a second thickness Tz,n of the material layer;
• calculating a second average thickness τn of the material layer across the work piece using the second thicknesses;
• for each zone, selecting a target thickness Tz,n+1 corresponding to the target thickness profile of the material layer;
• for each zone, calculating a removal rate coefficient Cz,n+1 using the first thickness Tz,n−1, the second thickness Tz,n, the first average thickness τn−1, the second average thickness τn, and the target thickness Tz,n+1;
• and
• for each zone, calculating a second pressure Pz,n+1 from the first pressure and the removal rate coefficient, wherein the second pressure is to be exerted against the second surface of the work piece within the first zone during removal of a second portion of the material layer.

A CMP apparatus comprising:

• a working surface;
• a work piece carrier configured to press a first surface of a work piece against the working surface, wherein the work piece carrier has a plurality of pressure zones, each pressure zone configured to exert a pressure on a second surface of the work piece;
• a multi-probe thickness measuring system having a plurality of probes disposed proximate to said working surface, wherein the multi-probe thickness measuring system is configured to measure a thickness of a material layer on the first surface of the work piece;
• and
• a controller electrically coupled to the multi-probe thickness measuring system and the work piece carrier, wherein the controller is configured to:
• receive first signals from the multi-probe thickness measuring system;
• determine a first thickness of the material layer underlying a first pressure zone of the work piece carrier using the first signals;
• cause the first zone of the work piece carrier to exert a first pressure against the second surface of the work piece:
• cause the working surface to remove a first portion from the material layer underlying the first zone;
• receive second signals from the multi-probe thickness measuring system;
• determine a second thickness of the material layer underlying the first zone using the second signals;
• receive as input a target removal amount projected to be removed from the material layer;
• calculate a second pressure from the first pressure, the first thickness, the second thickness, and the target removal amount;
• and
• cause the work piece carrier to change the pressure exerted by the first zone against the second surface of the work piece to the second pressure.