Wafer pressure regulation system for polishing machine

A controlled pressure regulation system suitable for use in a polishing machine that comprises a wafer carrier head for holding a wafer to be polished and a platen against which is pressed the wafer to be polished, the controlled pressure regulation system comprising:

• a first pressure regulator that generates a first pressure onto the platen to press the wafer against the wafer carrier head;
• a second pressure regulator that generates a second pressure onto the wafer carrier head to press the wafer against the platen;
• a first proportional integral controller connected to the first pressure regulator in a first feedback loop to control the generation of the first pressure onto the platen;
• a second proportional integral controller connected to the second pressure regulator in a second feedback loop to control the generation of the second pressure onto the wafer carrier head according to a difference of pressure between the first and second pressures;
• the first proportional integral controller further including a first operational amplifier in integrating configuration and a second operational amplifier in inverting configuration;
• and
• the second proportional integral controller further including a third operational amplifier in integrating configuration and fourth and fifth operational amplifiers in inverting configuration.

A method of pressure regulation applied during a polishing to press a wafer to be polished between a wafer carrier head and a platen, the method comprising:

• generating a first pressure onto the platen;
• controlling the generation of the first pressure onto the platen via a first control feedback loop;
• generating a second pressure onto the wafer carrier head;
• and
• controlling the generation of the second pressure onto the wafer carrier head according to a difference of pressure between the first and second pressure via a second control feedback loop.