Purged Reference Chip for Accurate Optical Metrology
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Solution Overview
Problem
In semiconductor manufacturing, integrated metrology modules face challenges due to process remnants like etch gases that affect the optical properties of reference chips used for calibration, leading to inaccurate measurements.
Innovation Solution
A reference chip purge device provides a flow of purge gas or air over the reference chip to protect it from process remnants, ensuring accurate measurements by maintaining the chip's optical properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If wafers are measured immediately after leaving the processing module, then rapid process feedback is achieved, but process remnants affect the optical properties of the reference chip
Solution Approach 1:
The system separates the reference chip environment from the wafer processing environment by introducing a dedicated purge gas flow path. The reference chip is isolated in a protected zone while the wafer undergoes processing, allowing rapid measurement without contaminating the reference chip.
Solution Approach 2:
Purge gas acts as an intermediary substance between the processed wafer and the reference chip. The gas flow creates a protective barrier that prevents process remnants from reaching the reference chip, enabling accurate calibration while maintaining rapid throughput.
2Measurement precision
If the reference chip is placed in close proximity to the wafer for calibration, then calibration accuracy is improved, but the reference chip is exposed to process remnants
Solution Approach 1:
Different regions of the measurement chamber have different environmental qualities. The reference chip region is protected with purge gas flow to maintain clean conditions, while the wafer region undergoes normal processing. This localized quality control allows the reference chip to remain close to the wafer for accurate calibration without exposure to harmful process remnants.
3Volume of moving object
If the IM module is made compact to fit loadport form factor, then space efficiency is improved, but there is insufficient space for a fan filter unit
Solution Approach 1:
The EFEM's existing air conditioning system serves multiple functions: it conditions air for both the wafer processing area and the IM module. This multi-functionality eliminates the need for a separate FFU in the compact IM module, maintaining space efficiency while providing necessary air conditioning.
Solution Approach 2:
The system leverages the EFEM's existing air conditioning infrastructure to serve the IM module's needs. Rather than requiring the IM module to have its own independent air conditioning system, it utilizes the parent system's capabilities, reducing complexity and space requirements.
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 purge system effectively prevents process remnants from contacting the reference chip, maintaining measurement accuracy and reliability by isolating it from contaminants.
Implementation Method 1
a reference chip purge device that provides a flow of purge gas or air over the reference chip
Implementation Method 2
Other gases used during processing may condense on the surface of the reference chip, which may also change the optical properties of the reference chip
Data Source
AI summary
An integrated metrology module includes a chuck for holding a sample and positioning the sample with respect to an optical metrology device, a reference chip for the optical metrology device, the reference chip being movable to various positions with respect to the optical metrology device, and a reference chip purge device provides a flow of purge gas or air over the reference chip while the reference chip is in the various positions. The reference chip purge device may be static or movable with the reference chip.