Off-axis Fiber Optic Sensor for Semiconductor Access
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Solution Overview
Problem
Existing fiber optic sensors face challenges in accessing tight spaces within semiconductor manufacturing environments without damaging the fiber due to the need for sharp bends, which can cause bending stress.
Innovation Solution
The development of compact optical assemblies that utilize a housing with a curved surface and reflective surface to change the direction of optical radiation, allowing for directional changes in a small footprint, using optical elements like hemispherical lenses to direct and reflect optical radiation, and allowing for bidirectional propagation through optical ports.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the fiber is bent at sharp angles to access tight spaces, then the sensor can reach hard-to-reach regions, but the fiber may be damaged due to bending stress
Solution Approach 1:
A non-metallic optical element (lens or prism) is introduced as an intermediary to redirect optical radiation between the fiber and the sensing location. This allows the fiber to remain straight while the optical element performs the directional change, eliminating bending stress on the fiber and enabling access to tight spaces without compromising fiber integrity
Solution Approach 2:
The mechanical bending of the fiber is replaced by an optical redirection mechanism using a lens or prism. Instead of physically bending the fiber to change direction, the patent uses optical elements to redirect the light path, substituting a mechanical solution with an optical one that avoids stress on the fiber
2Reliability
If metal capillary tubes are used to protect the fiber from bending stress, then the fiber is protected from damage, but the metal components may interfere with electric fields in the chamber
Solution Approach 1:
The material parameter of the protective structure is changed from metallic to non-metallic (such as ceramic or plastic). This parameter change eliminates the harmful effect of electric field interference while maintaining the protective function of the housing, allowing the fiber to be protected without introducing metal components into the electric field environment
Solution Approach 2:
The patent employs composite material structures where non-metallic materials (ceramic, plastic, or polymer) are used to construct the protective housing and optical elements. These composite non-metallic materials provide both mechanical protection for the fiber and electrical isolation from the chamber's electric fields, simultaneously addressing both protection and interference concerns
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
This solution enables improved performance in harsh environments with reduced optical fluence, prolonged component life, and simplified manufacturing, while maintaining non-metallic components to avoid interfering with electric fields, thus effectively addressing the challenge of accessing tight spaces without fiber damage.
Implementation Method 1
the optical element is configured to direct a first optical radiation incident on a first portion of the curved surface to exit a second portion of the curved surface after at least partially reflecting from at least a portion of the reflective surface
Implementation Method 2
an optical element disposed at least partially within the housing and having a curved surface... configured to direct a first optical radiation incident on a first portion of the curved surface to exit a second portion of the curved surface
Data Source
AI summary
The present application discloses embodiments of optical assemblies used in optical sensor systems where access to the equipment components or areas to be sensed is difficult. In one embodiment, an optical assembly may include a housing having an optical waveguide operative to guide an optical signal to an optical element configured to change the direction of propagation of the optical signal orthogonal to the original direction of propagation. The optical element may have a refractive surface and a reflective surface. Use of two such optical assemblies arranged optically in series enables the user to route an optical signal to propagate along an optical axis parallel to but laterally offset from the original axis of propagation. Such optical assemblies may allow optical access to regions of semiconductor manufacturing equipment such as process chambers, wafer supports, electrostatic chucks, showerheads, edge rings, or end effectors of wafer handling robots.