Rare Earth Oxide Coating for Sensor Wafer Etch Resistance
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Solution Overview
Problem
Current sensor wafers used in plasma etch environments face challenges with protective coatings that are either too thick, prone to particle generation, or fail to withstand etch processes for extended periods, leading to contamination and inaccurate temperature measurements.
Innovation Solution
A sensor wafer with a substrate and cover coated with a thin layer of rare earth oxide, such as yttria (Y2O3), which is applied using evaporative deposition or other IC fabrication processes to provide etch resistance and maintain measurement accuracy for at least 10 hours in plasma etch environments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If standard thin film materials such as polyimide or silicon oxide coatings are used to protect the sensor wafer, then the sensor wafer is protected from etching, but the coatings cannot withstand etch processes for extended periods (less than 10 hours) and may generate particles
Solution Approach 1:
The patent changes the material parameter from standard thin film materials (polyimide, silicon oxide) to rare earth oxide materials. This material substitution fundamentally alters the etch resistance properties, enabling the coating to withstand etch processes for extended periods (at least 10 hours) without generating particles, thereby resolving the contradiction between durability and contamination.
Solution Approach 2:
The patent employs composite material structure by combining rare earth oxide coating with the sensor wafer substrate. This composite approach creates a protective barrier that maintains both etch resistance and measurement accuracy, preventing particle generation while ensuring the coating survives the required duration in plasma etch environments.
2Duration of action of stationary object
If the coating is made extremely thick (e.g., approximately 10 μm thick for SiO2 and at least 100 μm thick for polyimide) to extend durability, then the coating can last at least 10 hours, but the thicker coating can introduce artifacts in temperature measurement and may warp the wafer
Solution Approach 1:
The patent changes the material composition parameter from conventional coatings to rare earth oxide, which provides superior etch resistance at much thinner thicknesses. This material parameter change enables the coating to achieve the required 10-hour durability without needing to be extremely thick, thereby avoiding temperature measurement artifacts and wafer warping while maintaining measurement precision.
3Reliability
If a silicon cover is used to protect the sensors, then the sensors are protected and the workpiece simulation is improved, but black or white silicon contamination is produced leading to particle generation
Solution Approach 1:
The patent changes the protective coating material parameter from silicon-based materials to rare earth oxide materials. This substitution eliminates the chemical compatibility issue that causes silicon etching and contamination, while maintaining sensor protection. The rare earth oxide coating is chemically inert to the etch processes, preventing black or white silicon contamination and particle generation.
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 rare earth oxide coating ensures prolonged etch resistance, minimal particle generation, and non-thermal perturbation, allowing for stable and accurate temperature measurements during plasma etch processes, exceeding the 10-hour durability requirement and maintaining measurement accuracy.
Implementation Method 1
a protective coating on a sensor wafer configured to resist etching by etch processes that etch the cover and/or substrate
Implementation Method 2
applied using evaporative deposition or other IC fabrication processes
Data Source
AI summary
A sensor wafer may be configured for in-situ measurements of parameters during an etch process. The sensor wafer may include a substrate, a cover, and one or more components positioned between the substrate and the cover. An etch-resistant coating is formed on one or more surfaces of the cover and/or substrate. The coating is configured to resist etch processes that etch the cover and/or substrate for a longer period than standard thin film materials of the same or greater thickness than the protective coating.