Conformal Film Thickness Measurement Using Angled Wafer Features
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Solution Overview
Problem
Conventional thin film measurement techniques in IC wafer fabrication are complex and rely heavily on optical methods like spectroscopic ellipsometry, making them difficult to operate and maintain, and they do not provide accurate inline measurements of film thickness during the fabrication process.
Innovation Solution
The method involves patterning angled geometric features on the IC wafer layer, allowing for the deposition of a thin film layer, where the thickness is measured by tracking changes in the geometric shapes, enabling accurate and straightforward thickness calculation without requiring complex optical illumination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional optical methods like spectroscopic ellipsometry are used for thin film measurement, then measurement capability is provided, but device complexity and difficulty of operation increase
Solution Approach 1:
The patent replaces complex optical measurement systems with a geometric tracking method that uses angular relationships and trigonometric calculations. Instead of using spectroscopic ellipsometry equipment, the system deposits geometric features at known angles and calculates film thickness through mathematical relationships between the geometric features' positions and angles, substituting mechanical/optical complexity with computational geometry.
Solution Approach 2:
The patent creates geometric copies or replicas of reference features at specific angles on the substrate. By depositing identical geometric patterns at known angular orientations and measuring their relative positions after film deposition, the system can calculate thickness without complex optical illumination, using the geometric copies as measurement references.
2Measurement precision
If conventional optical methods are used for film thickness measurement, then measurement is possible, but ease of operation deteriorates
Solution Approach 1:
The patent replaces complex optical measurement operations with simple geometric tracking. The method involves depositing geometric features at known angles and using trigonometric relationships to calculate thickness, which can be performed with basic measurement equipment and mathematical computation rather than complex optical illumination and analysis procedures.
3Measurement precision
If conventional optical methods are used for film thickness measurement, then measurement capability is provided, but measurement sensitivity and accuracy for inline measurement deteriorate
Solution Approach 1:
The patent performs preliminary action by depositing geometric reference features at known angles during the fabrication process itself, rather than adding measurement infrastructure later. These pre-deposited geometric features serve as built-in measurement references that enable rapid thickness calculation during inline operations, improving measurement efficiency and accuracy without time loss.
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 provides a reliable and simplified method for measuring film thickness inline during IC wafer fabrication, improving measurement sensitivity and accuracy by using geometric shapes to track film deposition, thus overcoming the limitations of traditional optical methods.
Implementation Method 1
A conformal coating is formed over a geometric feature
Data Source
AI summary
Embodiments of the invention provide a method that includes forming an IC layer having an inactive region and an active region. The active region includes a device-under-fabrication (DUF). The inactive region includes a geometric feature having a geometric shape. A film is deposited over the active DUF and the geometric feature such that a first portion of the film will be part of the active DUF, and such that a second portion of the film is over the geometric feature. A geometric shape of the film over the geometric feature matches the geometric shape of the geometric feature. Determining a thickness of the film is based at least in part a difference between a footprint of the geometric shape of the film and a footprint of the geometric shape of the geometric feature.