Integrated Wafer Bow Measurement for Real-Time In-Situ Control
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Solution Overview
Problem
Current wafer bow measurement technologies are limited by being unsuitable for in-situ, real-time measurements, often requiring standalone tools that measure wafers point-by-point or have limited measurement ranges, and are not designed to handle hot wafers, leading to inadequate process control and potential damage during etching processes.
Innovation Solution
Integration of an optical sensor, such as a laser triangulation-based distance sensor, on a wafer processing tool with linear and rotational stages for real-time wafer bow measurements, combined with a calibration standard and sensors for environmental compensation, allowing for accurate and continuous monitoring and control of wafer bow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If stand-alone metrology tools are used for wafer bow measurement, then measurement capability is provided, but real-time in-situ measurement and process control are not achieved
Solution Approach 1:
The patent combines the metrology tool with the deposition tool into an integrated system. The optical sensor is mounted on the deposition tool's electrostatic chuck assembly, allowing simultaneous deposition and wafer bow measurement. This merging eliminates the need for separate stand-alone metrology tools and enables real-time in-situ measurements during the deposition process, directly resolving the contradiction between measurement capability and measurement time.
Solution Approach 2:
The system performs wafer bow measurements during the deposition process itself, before the wafer is removed for separate characterization. By measuring the wafer bow in-situ during deposition, the system obtains real-time data that can be used for immediate process control adjustments, eliminating the time delay associated with post-deposition stand-alone measurements.
2Measurement precision
If point-by-point measurement methods are used, then measurement is possible, but measurement speed and real-time capability are limited
Solution Approach 1:
The patent employs a dynamic measurement approach where the optical sensor scans across the wafer surface during deposition rather than performing static point-by-point measurements. The sensor moves with the wafer or scans across it continuously, capturing multiple measurement points in rapid succession. This dynamic scanning method maintains measurement accuracy while dramatically increasing measurement speed and enabling real-time wafer bow characterization.
3Measurement precision
If the upper electrode is lowered to measure wafer height, then gap measurement is obtained, but risk of electrode-wafer contact and damage increases
Solution Approach 1:
The patent replaces the mechanical contact-based gap measurement method with a non-contact optical measurement system. An optical sensor measures wafer bow and height parameters from a distance without requiring the upper electrode to physically approach or contact the wafer surface. This substitution eliminates the risk of electrode-wafer contact and associated damage while maintaining measurement accuracy.
Solution Approach 2:
The optical sensor acts as an intermediary between the measurement system and the wafer surface. Instead of directly contacting the wafer with the upper electrode, the optical sensor mediates the measurement process by detecting wafer height and bow parameters through light interaction. This intermediary approach enables accurate gap and height measurements without the harmful mechanical contact that could damage either the electrode or wafer.
4Productivity
If in-line optical sensing is implemented, then real-time measurement is achieved, but system complexity increases
Solution Approach 1:
The optical sensor system is designed to perform multiple functions: measuring wafer bow, determining wafer height, monitoring gap dimensions, and providing real-time process control data. By making the metrology system multi-functional, the patent achieves comprehensive real-time measurement capabilities without proportionally increasing system complexity. The same optical sensor platform serves multiple measurement purposes, improving productivity while controlling complexity.
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
Enables real-time, accurate wafer bow measurements that improve process monitoring and control, reducing the risk of electrode damage and plasma variation, and facilitating effective bow compensation in high-volume manufacturing.
Implementation Method 1
an optical sensor, such as a laser triangulation-based distance sensor
Data Source
AI summary
In some examples, a wafer bow measurement system comprises a measurement unit including: a wafer support assembly to impart rotational movement to a measured wafer supported in the measurement unit; an optical sensor; a calibration standard to calibrate the optical sensor; a linear stage actuator to impart linear direction of movement to the optical sensor; a wafer centering sensor to determine a centering of the measured wafer supported in the measurement unit; and a wafer alignment sensor to determine an alignment of the measured wafer supported in the measurement unit.