Slurry monitoring device, CMP system and method of in-line monitoring a slurry

A chemical mechanical polish (CMP) system, comprising:

• at least one CMP apparatus;
• a first slurry supply unit and a second slurry supply unit;
• a first slurry supply pipe loop connected to the first slurry supply unit and the at least one CMP apparatus;
• a second slurry supply pipe loop connected to the second slurry supply unit and the at least one CMP apparatus;
• and
• a slurry monitoring device connected to the first slurry supply pipe loop and the second slurry supply pipe loop, wherein the slurry monitoring device comprises:
• a slurry metrology cell, in communication with the first slurry supply pipe loop and the second slurry supply pipe loop, and configured to accommodate a slurry;
• a plurality of light sources configured to emit light beams on the slurry in the slurry metrology cell, wherein the plurality of light sources comprise a first light source emitting a first light beam and a second light source emitting a second light beam;
• at least one optical lens disposed between the plurality of light sources and the slurry metrology cell, and configured to modify a size of a light spot of the light beams impinged on the slurry;
• at least one optical chopper disposed between the plurality of light sources and the slurry metrology cell;
• and
• a first optical detector configured to detect an intensity of the first light beam scattered by abrasive particles in the slurry, and a second optical detector configured to detect an intensity of the second light beam scattered by the abrasive particles in the slurry,
• wherein the plurality of light sources, the at least one optical chopper and the at least one optical lens are arranged in a direction perpendicular to a flow direction of the slurry, wherein the first light beam has a first incident direction toward the first optical detector, the second light beam has a second incident direction toward the second optical detector, and the first incident direction and the second incident direction are perpendicular to the flow direction of the slurry.

A method of in-line monitoring a slurry, comprising:

• conducting the slurry from a first slurry supply pipe loop to a slurry metrology cell;
• emitting a first light beam and a second light beam toward the slurry metrology cell;
• modifying a pulse duration of at least one of the first light beam and the second light beam by an optical chopper;
• impinging the first light beam and the second light beam on the slurry accommodated in the slurry metrology cell through optical lenses;
• detecting an intensity of the first light beam scattered by abrasive particles of the slurry by a first optical detector, and detecting an intensity of the second light beam scattered by the abrasive particles of the slurry by a second optical detector;
• and
• obtaining estimated sizes of the abrasive particles in the slurry based on the intensity of the first light beam and the intensity of the second light beam scattered by the abrasive particles of the slurry,
• wherein the optical chopper, the optical lenses and the first and second optical detectors are arranged in a direction perpendicular to a flow direction of the slurry,
• wherein the first light beam has a first incident direction toward the first optical detector, the second light beam has a second incident direction toward the second optical detector, and the first incident direction and the second incident direction are perpendicular to the flow direction of the slurry.