Optical Sensor System for Wafer Warpage Measurement
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Solution Overview
Problem
Current lithographic systems inadequately handle wafer warpage, leading to potential damage and inefficiencies due to reliance on estimated warpage values rather than actual measurements, and fail to account for wafer-to-wafer variations, resulting in suboptimal performance and accuracy.
Innovation Solution
A sensor system comprising a substrate support and sensor devices with optical emitters and receivers, coupled with a controller that determines measurement heights and compensates for gravitational sag, allowing for precise warpage measurement and shape determination of substrates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If estimated warpage values are used in exposure recipes, then damage prevention and throughput maintenance are achieved, but measurement precision and manufacturing accuracy deteriorate due to reliance on maximum/estimated values rather than actual measurements
Solution Approach 1:
The sensor system performs warpage measurements on substrates before they are processed by the lithographic apparatus. The controller determines warpage information based on sensor data and generates exposure recipes incorporating actual warpage measurements, preparing everything in advance to prevent damage and optimize processing.
Solution Approach 2:
The patent replaces mechanical contact-based warpage measurement methods with an optical sensing system. The sensor devices emit radiation beams and detect reflected beams to determine surface heights and warpage information without physical contact, eliminating mechanical interference and improving measurement accuracy.
2Productivity
If maximum/estimated warpage values are entered into exposure recipes, then time loss is prevented through batch processing, but manufacturing precision deteriorates due to inability to optimize for individual wafer variations
Solution Approach 1:
The system measures warpage information for each substrate before processing and pre-generates optimized exposure recipes tailored to each individual substrate's actual warpage characteristics. This preliminary customization enables both high throughput and precise exposure for each wafer.
Solution Approach 2:
The controller adjusts exposure recipe parameters based on actual warpage measurements of each substrate. By changing exposure parameters according to measured warpage information, the system optimizes exposure accuracy for each individual substrate while maintaining efficient batch processing.
3Manufacturing precision
If actual warpage measurements are implemented for each substrate, then manufacturing precision and exposure accuracy are improved, but device complexity increases due to additional sensor systems and measurement processes
Solution Approach 1:
The sensor system is designed to measure warpage information across multiple substrates using the same optical emitter and receiver configuration. The controller processes measurements from different substrates by comparing them against stored reference data, enabling universal application without requiring separate measurement systems for each substrate.
Solution Approach 2:
The system creates a digital copy of the substrate surface topography through optical measurements. The controller stores measured warpage information and compares it with reference warpage data, using these digital representations to generate optimized exposure recipes without needing physical copies or repeated complex measurements.
4Device complexity
If gravitational sag is not compensated for in measurements, then device complexity is reduced, but measurement precision deteriorates due to unaccounted substrate deformation
Solution Approach 1:
The patent uses optical sensing to measure substrate shape and detect gravitational sag effects without mechanical contact. The controller analyzes the measured shape data to distinguish between actual warpage and gravitational deformation, compensating for sag through computational methods rather than mechanical correction.
Solution Approach 2:
The controller acts as an intermediary that processes raw sensor measurements and compensates for gravitational sag effects. By comparing measured shapes with reference data and applying computational corrections, the controller eliminates the need for complex mechanical sag compensation mechanisms while maintaining measurement precision.
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 accurate warpage measurement and compensation, enhancing the handling and processing of substrates by providing real-time data for improved exposure accuracy and preventing damage, thus optimizing performance and reducing time losses.
Implementation Method 1
an optical receiver to receive the radiation beams reflected from the surface
Data Source
AI summary
A sensor system for measuring a shape of a substrate, the sensor system include: a substrate support to support a surface of the substrate; at least one sensor device, each sensor device including an optical emitter to emit radiation onto the surface of the substrate, and an optical receiver to receive the radiation reflected from the surface; and a controller. The controller is configured to: determine at least one measurement height of the surface of the substrate above each of the at least one sensor device, based on the received radiation; compensate for gravitational sag of the substrate relative to a calibration height; and determine the shape of the substrate based on a comparison of the calibration height and the at least one measurement height.