Semiconductor Substrate Thickness Measurement Using Optical Interferometry
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Substrate thickness variations, particularly warpage, lead to poor contact between electrical connections in semiconductor packages, causing issues like non-contact-opens and bump bridging during thermal compression bonding processes, which existing measurement methods fail to address effectively.
Innovation Solution
A system using a pedestal with a planar support surface and a vacuum force to immobilize the substrate, combined with a measurement probe assembly that determines thickness variations using confocal technology or white light interferometry, allowing for precise measurement of chip and bump thickness variations and substrate slope planes to ensure proper die bonding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If contact micrometer or dual FRT system is used to measure substrate thickness, then measurement capability is provided, but measurement time is excessive (30 minutes per substrate)
Solution Approach 1:
The patent replaces mechanical measurement systems (contact micrometer, dual FRT system with physical probes) with an optical measurement system that uses light interference patterns to measure substrate thickness and warpage. This substitution enables non-contact, rapid measurement across the entire substrate surface simultaneously, reducing measurement time from 30 minutes to a fraction of that time while maintaining or improving measurement precision.
Solution Approach 2:
The patent creates an optical copy or digital representation of the substrate surface topography by capturing light interference patterns. Instead of physically probing the substrate, the system generates a digital model of the substrate thickness variations and warpage, allowing for rapid analysis and measurement without physical contact or time-consuming mechanical scanning.
2Reliability
If substrate thickness measurement is performed to detect warpage, then bonding quality can be improved, but existing methods are too slow for real-time screening
Solution Approach 1:
The patent replaces slow mechanical measurement methods with rapid optical measurement technology that can capture complete substrate topography maps in seconds. This enables real-time quality screening where every substrate can be measured and evaluated for warpage and thickness variations before bonding, ensuring bonding quality without sacrificing production throughput.
Solution Approach 2:
The patent enables continuous, real-time measurement of substrate thickness and warpage throughout the manufacturing process. The optical measurement system can operate continuously at high speed, providing uninterrupted quality monitoring that allows every substrate to be screened in real-time rather than through slow, discrete measurements, thereby maintaining both high reliability and productivity.
3Ease of manufacture
If substrate warpage is not controlled, then manufacturing process is simpler, but bonding defects occur (non-contact-opens, bump bridging)
Solution Approach 1:
The patent performs preliminary measurement and detection of substrate warpage and thickness variations before the bonding process. By using rapid optical measurement to identify substrates with excessive warpage or thickness variations beforehand, the system allows for corrective actions or substrate rejection prior to bonding, preventing bonding defects such as non-contact-opens and bump bridging while maintaining manufacturing efficiency.
Solution Approach 2:
The patent implements a feedback mechanism where measurement data on substrate warpage and thickness is obtained in real-time and used to control or adjust subsequent bonding processes. The measurement system provides immediate feedback on substrate quality, enabling dynamic adjustment of bonding parameters or substrate selection to ensure reliable electrical connections and prevent bonding defects.
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 approach significantly reduces substrate warpage, enabling accurate measurement and bonding, improving manufacturing efficiency by allowing 100% of substrates to be screened in real-time, reducing measurement time from 30 minutes to 5 seconds per substrate without sacrificing accuracy or repeatability.
Implementation Method 1
a vacuum device coupled to the pedestal to apply the vacuum force to the substrate
Implementation Method 2
a measurement probe assembly that determines thickness variations using confocal technology or white light interferometry
Data Source
AI summary
A system for determining thickness variation values of a semiconductor substrate comprises a substrate vacuumed to a pedestal that defines a reference plane for measuring the substrate. A measurement probe assembly determines substrate CTV and BTV values, and defines a substrate slope angle. A thermal bonding assembly attaches a die to the substrate at a bonding angle congruent with the substrate slope angle. A plurality of substrates are measured using the same reference plane on the pedestal. Associated methods and processes are disclosed.