Electron Beam Evaporation Electrode for Impurity Detection
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Solution Overview
Problem
In electron-beam metal evaporation/deposition systems, impurities in metal slugs, such as carbon, cause photoresist cross-linking and 'gold spitting,' leading to defects on semiconductor wafers, which are difficult to detect in real-time, resulting in production delays and yield losses.
Innovation Solution
A method and apparatus that monitor electrical signals from an electrode in the deposition chamber to detect changes indicative of impurity concentrations in the metal slug, allowing for real-time detection of increased impurities and triggering preventative maintenance, such as replacing the metal slug, to prevent cross-linking and spitting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If electron-beam evaporation is used to deposit metal, then deposition efficiency is improved, but impurities cause photoresist cross-linking and gold spitting
Solution Approach 1:
The patent applies preliminary action by monitoring the metal slug for impurities before they cause defects during evaporation. The system detects impurity concentration in real-time and triggers alerts or automatic shutdowns before cross-linking or spitting occurs, preventing defects rather than detecting them after formation.
Solution Approach 2:
The patent implements feedback through a monitoring system that continuously measures impurity concentration in the metal slug during electron-beam evaporation. The system provides real-time feedback about impurity levels and triggers appropriate responses (alerts, process adjustments, or shutdowns) when threshold values are exceeded, creating a closed-loop control system.
2Measurement precision
If real-time monitoring is implemented, then defect detection capability is improved, but system complexity increases
Solution Approach 1:
The patent uses an intermediary monitoring system that indirectly detects impurity conditions by measuring parameters such as electron beam current, voltage, or radiation levels. Rather than directly observing impurities or defects, the system uses these measurable proxies to infer impurity concentration and predict potential defects, simplifying the detection mechanism.
Solution Approach 2:
The patent replaces complex mechanical inspection systems with electrical and electronic monitoring. Instead of using physical probes or mechanical sensors to detect impurities, the system uses electrical measurements (current, voltage, resistance changes) and electronic signal processing to monitor impurity concentration and predict 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 enables early detection and prevention of impurity-related defects, reducing the number of cross-linked photoresist and metal nodules, thereby increasing yield and minimizing production disruptions.
Implementation Method 1
a metal source (also referred to herein as a metal slug) is heated in a vacuum chamber, maintained at about 10−7 Torr in some systems, until the metal melts and atoms evaporate from the metal source. The metal source may be heated by any of a number of methods, including, for example, resistive heating or by directing an electron-beam into the metal source.
Implementation Method 2
The metal atoms evaporated from the metal source travel through the vacuum chamber and deposit on one or more semiconductor wafers
Implementation Method 3
monitoring, during the electron-beam metal evaporation/deposition process, a first electrical signal provided by an electrode that is located in a deposition chamber of the electron-beam evaporator and physically displaced from the metal slug
Data Source
AI summary
An electrode system configured to be positioned within a vacuum chamber of an electron-beam metal evaporation and deposition apparatus including a metal slug from which metal is evaporated during operation of the electron-beam metal evaporation and deposition apparatus. The electrode system includes a substantially ring-shaped electrode formed of a conductive material and a plurality of insulating standoffs configured to support the substantially ring-shaped electrode in the vacuum chamber in a position substantially surrounding the metal slug.