Head Nozzle Flow-Passage System for Optical Path Clarity
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Solution Overview
Problem
Existing substrate polishing apparatuses face challenges in accurately measuring film thickness during the CMP process due to foreign matter like polishing liquid and debris on the substrate surface, which lowers light transmittance.
Innovation Solution
A substrate polishing apparatus is designed with a head nozzle that includes a first and second flow-passage system. These systems form a liquid flow across the optical path, using a fluid chamber, aperture, liquid outlet port, and suction port to remove foreign matter, ensuring the optical path is filled with a transparent liquid for accurate film thickness measurement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If an optical film-thickness measuring device directs light onto the substrate surface during polishing, then film thickness can be measured, but foreign matter on the surface lowers light transmittance and measurement accuracy
Solution Approach 1:
The patent extracts and removes foreign matter (polishing liquid and debris) from the optical path between the light source and substrate surface. The flow-passage system actively removes contaminants that would otherwise block or scatter the measurement light, ensuring clear optical transmission for accurate film thickness measurement.
Solution Approach 2:
The patent introduces a transparent liquid as an intermediary medium in the optical path. This transparent liquid fills the measurement area and provides a clear transmission medium for the light, replacing or supplementing the polishing liquid that causes opacity. The transparent liquid acts as a mediator that allows light to pass through while still maintaining the polishing function.
2Reliability
If polishing liquid is supplied onto the substrate surface during CMP, then polishing function is maintained, but the polishing liquid dilutes and reduces measurement accuracy
Solution Approach 1:
The patent segments the liquid management into two separate flow-passage systems: one for supplying polishing liquid to maintain polishing function, and another for supplying transparent liquid to the measurement area for accurate measurement. This segmentation allows both functions to operate simultaneously without interference, with each system serving its specific purpose in the polishing and measurement process.
Solution Approach 2:
The patent applies local quality by providing different liquid types in different locations: polishing liquid is supplied to the general polishing area to maintain the polishing function, while transparent liquid is specifically supplied to the measurement area (through the flow-passage system) to ensure optical clarity. Each location receives the appropriate liquid quality needed for its specific function.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The apparatus enables high-accuracy film thickness measurement during substrate polishing by maintaining light transmittance and preventing dilution of the polishing liquid, while also ensuring efficient removal of foreign matter from the optical path.
Implementation Method 1
an optical film-thickness measuring device provided in the substrate polishing apparatus. This optical film-thickness measuring device is configured to direct light onto a surface of the substrate, and determine a film thickness based on a spectral waveform of light reflected from the substrate
Implementation Method 2
determine a film thickness based on a spectral waveform of light reflected from the substrate
Implementation Method 3
the head nozzle includes a first flow-passage system and a second flow-passage system each configured to form a flow of liquid across an optical path of the light and the reflected light
Implementation Method 4
a liquid suction port configured to suck the liquid on the surface of the substrate
Data Source
AI summary
The substrate polishing apparatus capable of measuring a film thickness of a substrate with high accuracy without decreasing a transmittance of light when measuring the film thickness of a substrate being polished is disclosed. The substrate polishing apparatus includes: a stage; a polishing head configured to hold a polishing pad; a polishing-liquid supply nozzle; a film-thickness measuring head; a spectrum analyzer; and a head nozzle to which the film-thickness measuring head is attached. The head nozzle includes a first flow-passage system and a second flow-passage system each configured to form a flow of liquid across an optical path of light and reflected light, the first flow-passage system has an aperture located on the optical path, the second flow-passage system has a liquid outlet port and a liquid suction port located at both sides of the aperture.