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

A chemical mechanical polish (CMP) system, comprising:

• a CMP apparatus;
• a slurry supply unit;
• a slurry supply pipe loop connected to the slurry supply unit and the CMP apparatus;
• and
• a slurry monitoring device connected to the slurry supply pipe loop, wherein the slurry monitoring device comprises:
• a slurry metrology cell, in communication with the 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;
• a plurality of optical lenses 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 optical lenses and the slurry metrology cell;
• and
• a plurality of optical detectors configured to detect intensities of the light beams scattered by abrasive particles in the slurry,
• wherein the light beams have incident directions toward the plurality of optical detectors, and the incident directions are perpendicular to a flow direction of the slurry.

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

• conducting a 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;
• impinging the first light beam and the second light beam on the slurry accommodated in the slurry metrology cell through optical lenses;
• modifying a pulse duration of at least one of the first light beam and the second light beam from the optical lenses by an optical chopper;
• 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 is disposed between the optical lens and the slurry metrology, and
• 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.