Pressure control system and polishing apparatus

A pressure control method comprising:

• supplying a first pressurized fluid from a master pressure controller to a first calibration chamber;
• supplying a second pressurized fluid from said master pressure controller to a second calibration chamber;
• supplying a third pressurized fluid from a first pressure controller to said first calibration chamber;
• detecting a differential pressure between the first pressurized fluid and the third pressurized fluid;
• adjusting a pressure of said third pressurized fluid so that the differential pressure between the first pressurized fluid and the third pressurized fluid becomes zero or approximately zero;
• supplying a fourth pressurized fluid from a second pressure controller to said second calibration chamber;
• detecting a differential pressure between the second pressurized fluid and the fourth pressurized fluid;
• and
• adjusting a pressure of the fourth pressurized fluid so that the differential pressure between the second pressurized fluid and the fourth pressurized fluid becomes zero or approximately zero.

A pressure control system comprising:

• a first pressure controller configured to supply a first pressurized fluid to a first pressure-controlled section;
• a master pressure controller configured to supply a second pressurized fluid;
• a first calibration chamber corresponding to said first pressure controller, the first pressurized fluid and the second pressurized fluid being supplied to said first calibration chamber, said first calibration chamber being configured to detect a differential pressure between the first pressurized fluid and the second pressurized fluid;
• and
• an arithmetic device configured to receive a signal from said first calibration chamber and adjust an output of said first pressure controller so that the differential pressure between the first pressurized fluid and the second pressurized fluid becomes zero or approximately zero.

A polishing apparatus comprising:

• a polishing table having a polishing surface:
• and a substrate holding apparatus for holding a substrate and pressing the substrate against said polishing surface, comprising:
• a pressure control system comprising:
• a first pressure controller configured to supply a first pressurized fluid to a first pressure-controlled section;
• a master pressure controller configured to supply a second pressurized fluid;
• a first calibration chamber corresponding to said first pressure controller, the first pressurized fluid and the second pressurized fluid being supplied to said first calibration chamber, said first calibration chamber being configured to detect a differential pressure between the first pressurized fluid and the second pressurized fluid;
• and
• an arithmetic device configured to receive a signal from said first calibration chamber and adjust an output of said first pressure controller so that the differential pressure between the first pressurized fluid and the second pressurized fluid becomes zero or approximately zero;
• a top ring body for holding the substrate;
• a plurality of pressure chambers formed in said top ring body;
• and
• a plurality of fluid passages configured to connect said pressure chambers to said pressure controllers, respectively.