Wafer carrier with pressurized membrane and retaining ring actuator
View Patent ↗A wafer carrier for controlling downward force and edge effect during chemical mechanical planarization. A retaining ring actuator is disposed within the retaining ring to control the height of the retaining ring relative to the bottom surface of the wafer carrier. An inflatable membrane is disposed across the bottom surface of the wafer carrier such that pressure in the bladder is independently regulated to control the downward force acting on the wafer during CMP. In addition, an edge control bladder may also be disposed within the carrier such that if the pressure in the bladder is also regulated, the amount of force on the edge of the wafer changes. By regulating retaining ring actuator pressure, inflatable membrane pressure, and edge control bladder pressure, non-uniformities in the wafer surface and edge effect may be addressed during CMP.
1. A wafer carrier comprising:
a housing having a plate;
a retaining ring characterized by an inner diameter and coupled to the plate of the housing, said retaining ring having a groove disposed therein;
a retaining ring actuator disposed within the groove, said retaining ring actuator sized and dimensioned to substantially conform to the size and dimensions of the groove, said retaining ring actuator able to be pressurized;
an edge control bladder disposed within the wafer carrier, said bladder further disposed such that pressure changes in the bladder will change the force applied to the edge of a wafer held by the wafer carrier; and
a soft membrane extending across a bottom surface of a piston plate in the wafer carrier, said membrane further disposed within the inner diameter of the retaining ring and able to be pressurized.
2. The wafer carrier of claim 1 wherein the retaining ring actuator pressure may be changed effectuating a change in pressure applied to the retaining ring.
3. The wafer carrier of claim 1 wherein the soft membrane may be pressurized to apply force to a backside of a wafer being held by the wafer carrier.
4. The wafer carrier of claim 1 wherein pressure within the retaining ring actuator, pressure behind the inflatable membrane, and pressure within the edge control bladder are regulated independently.
5. A wafer carrier comprising:
a housing having a plate;
a retaining ring characterized by an inner diameter and coupled to the plate of the housing, said retaining ring having a groove disposed therein;
a retaining ring actuator disposed within the groove, said retaining ring actuator sized and dimensioned to substantially conform to the size and dimensions of the groove, said retaining ring actuator able to be pressurized;
a ring of resilient material bladder disposed within the wafer carrier, said ring further disposed such that the resilient material applies force to the edge of a wafer held by the wafer carrier; and
a soft membrane extending across a bottom surface of a piston plate in the wafer carrier, said membrane further disposed within the inner diameter of the retaining ring and able to be pressurized.
6. The wafer carrier of claim 5 wherein the retaining ring actuator pressure may be changed effectuating a change in pressure applied to the retaining ring.
7. The wafer carrier of claim 5 wherein the soft membrane may be pressurized to apply force to a backside of a wafer being held by the wafer carrier.
8. The wafer carrier of claim 5 wherein pressures in the retaining ring actuator and behind the soft membrane are regulated independently.
9. A method for wafer planarization comprising:
providing a wafer carrier comprising:
a housing having a plate;
a retaining ring characterized by an inner diameter and coupled to the plate of the housing, said retaining ring having a groove disposed therein;
a retaining ring actuator disposed within the groove, said retaining ring actuator sized and dimensioned to substantially conform to the size and dimensions of the groove, said retaining ring actuator able to be pressurized;
an edge control bladder disposed within the wafer carrier to change the force applied to the edge of a wafer held by the wafer carrier; and
a soft membrane extending across a bottom surface of a piston plate in the wafer carrier, said membrane further disposed within the inner diameter of the retaining ring and able to be pressurized;
pressurizing a soft membrane in a wafer carrier to apply downward force to a wafer during CMP;
pressurizing a retaining ring actuator to adjust a force of a retaining ring acting on a polishing pad; and
pressurizing the edge control bladder disposed within the wafer carrier to change the force applied to the edge of a wafer held by the wafer carrier.
10. The method of claim 9 further comprising the step of independently regulating pressure behind the soft membrane, pressure within the retaining ring actuator, and pressure within the edge control bladder.