In-die Metrology for Semiconductor Layer Thickness Measurement
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Solution Overview
Problem
Current methods for measuring properties of semiconductor layers are either destructive, limited in scope, or prone to substrate damage, and alignment challenges hinder accurate measurement and process control in semiconductor manufacturing.
Innovation Solution
A method involving the emission and analysis of a light beam spectrum reflected from a substrate to determine layer properties, such as thickness and refractive index, which are compared to reference values to provide real-time instructions for process tools, allowing for non-destructive measurement and improved process control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If cutting (scribe and break) the substrate to expose cross-section for microscopy measurement, then measurement precision is improved, but the substrate is destroyed and manufacturing productivity is reduced
Solution Approach 1:
The patent replaces mechanical cutting and microscopy with optical measurement systems. Specifically, it uses reflectometry and spectroscopy to non-contact measure layer thickness and properties, eliminating the need for physical substrate destruction while maintaining measurement accuracy.
Solution Approach 2:
The patent creates optical copies or representations of layer properties through reflected light spectra rather than direct physical examination. The spectral signature of the substrate acts as a copy that contains information about layer thickness and composition without requiring physical access to the layers themselves.
2Reliability
If using SEM beam for non-destructive measurement, then substrate integrity is preserved, but alignment difficulty and time consumption increase
Solution Approach 1:
The patent employs self-aligning measurement features such as gratings or periodic structures that are inherently positioned on the substrate. These features automatically provide alignment references without requiring complex manual or automated alignment procedures, thereby reducing alignment time while maintaining substrate integrity.
Solution Approach 2:
The patent incorporates alignment features during the manufacturing process itself, before final measurement. By pre-positioning reference gratings or markers as part of the device structure, the measurement system has built-in alignment references that eliminate time-consuming alignment steps during testing.
3Difficulty of detecting and measuring
If using proxy features between dies for measurement, then measurement capability is enabled, but alignment precision deteriorates due to difficulty in positioning within small spot size
Solution Approach 1:
The patent transitions from two-dimensional planar measurement to three-dimensional optical measurement. By using reflectometry that measures light reflection from the substrate surface and underlying layers, it gains access to layer properties without requiring precise lateral positioning, effectively adding a vertical measurement dimension that bypasses alignment difficulties.
Solution Approach 2:
The patent creates measurement features that serve multiple functions: they act as both structural elements of the device and as optical measurement references. The same gratings or periodic structures that are functional for the semiconductor device also serve as alignment and measurement references, eliminating the need for separate proxy features and improving positioning accuracy.
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 non-destructive, accurate measurement of semiconductor layer properties, facilitating real-time process adjustments and calibration of process tools, thereby enhancing semiconductor manufacturing efficiency and precision.
Implementation Method 1
receiving a reflected light beam from the substrate
Implementation Method 2
determining a spectrum of the reflected light beam
Data Source
AI summary
Various embodiments include a method for providing instructions to a process tool. The method includes emitting an incident light beam at a substrate, receiving a reflected light beam from the substrate and determining a spectrum of the reflected light beam. The method further includes determining a first property of a first layer of the substrate and a second property of a second layer of the substrate, based on the spectrum determination. The method further includes comparing the first property of the first layer to a first reference property and comparing the second property of the second layer to a second reference property. The method further includes determining the instructions based on the first property comparison and the second property comparison; and providing the instructions to the process tool.