Patent ID: 11883837
Assignee: TOKYO ELECTRON LIMITED
Field: Measurement (Instruments)
Classification: CPC B  G  H | IPC B  G  H

Claim 0:
1. A system for dispensing liquid on a substrate, the system comprising:
a substrate holder configured to hold a substrate and rotate the substrate about an axis;
a dispense unit configured to dispense a liquid on a working surface of the substrate while the substrate is being rotated on the substrate holder;
a first laser configured to direct a first laser beam at an edge of the working surface of the substrate;
a first detector positioned to capture scattered light from the first laser beam directed at the edge of the working surface of the substrate;
a second laser configured to direct a second laser beam at an interior portion of the working surface of the substrate;
a second detector positioned to capture scattered or reflected light from the second laser beam directed at the interior portion of the working surface of the substrate;
a processor configured to monitor scattered or reflected light from the second laser beam directed at the interior portion of the working surface of the substrate to monitor intermediate progress of the liquid, and to monitor scattered light from the first laser beam directed at the edge of the working surface of the substrate to identify a pattern of scattered light indicating that the liquid has reached the edge of the substrate; and
the processor further configured to identify an actual coating time of the liquid beginning from initiation of a given dispense of the liquid onto the working surface until the liquid reaches the edge of the working surface, and compare the actual coating time of the liquid to an expected coating time of the liquid.