Reticle Deformation Detection for Lithography Aberration Correction
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Solution Overview
Problem
Lithography processes in semiconductor manufacturing are affected by reticle deformation due to temperature fluctuations, leading to aberrations and manufacturing errors that limit structure width reduction and device density.
Innovation Solution
An exposure tool with a reticle deformation detector measures reticle deformation in real-time, allowing for adjustments to optical components such as the projection lens and reticle replacement to correct aberrations during the scanning process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If real-time reticle deformation measurement and adjustment is implemented, then lithography accuracy is improved, but device complexity increases
Solution Approach 1:
The system pre-determines deformation metrics for different fields and pre-calculates adjustment parameters before scanning begins. This allows the complex correction calculations to be performed in advance rather than in real-time during scanning, reducing the computational burden on the exposure tool while maintaining high lithography accuracy.
Solution Approach 2:
A separate deformation metrics determination system and adjustment parameter calculation system are introduced as intermediaries between the reticle and the projection lens. These intermediary systems handle the complex measurement and calculation tasks, allowing the exposure tool to implement corrections without requiring complex real-time processing capabilities.
2Manufacturing precision
If reticle deformation correction is performed during scanning, then manufacturing errors are reduced, but scanning time increases
Solution Approach 1:
Deformation metrics for all fields are determined in advance before the scanning process begins. Adjustment parameters are pre-calculated based on these metrics, allowing the exposure tool to simply execute pre-determined corrections during scanning without performing complex real-time calculations, thus minimizing impact on scanning speed.
Solution Approach 2:
The system performs deformation measurements and adjustments at periodic intervals corresponding to different fields during scanning. Rather than continuous real-time correction, the system applies corrections at discrete field boundaries based on pre-calculated parameters, reducing the time overhead while maintaining manufacturing precision.
3Stability of the object's composition
If multiple deformation metrics are determined for different fields, then lithography uniformity is improved, but measurement precision requirements increase
Solution Approach 1:
The system determines deformation metrics specifically for each field region rather than treating the reticle as a uniform whole. This allows the measurement system to focus on local deformation characteristics relevant to each field, reducing the overall measurement precision requirements while maintaining lithography uniformity across different fields.
Solution Approach 2:
The reticle scanning process is divided into multiple field segments, with deformation metrics determined for each segment. This segmentation allows the measurement system to handle smaller, more manageable deformation variations in each field, reducing the precision burden compared to measuring the entire reticle as a single unit.
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
Reduces manufacturing errors and improves lithography accuracy, enabling the formation of structures with reduced dimensions and enhanced device density on the wafer.
Implementation Method 1
performing a first scan of a first field of a wafer, the first scan including projecting an electromagnetic field through a reticle and onto the first field of the wafer
Data Source
AI summary
Some implementations described herein provide an exposure tool. The exposure tool includes a reticle deformation detector and one or more processors configured to obtain, via the reticle deformation detector, reticle deformation information associated with a reticle during a scanning process for scanning multiple fields of a wafer. The one or more processors determine, based on the reticle deformation information, a deformation of the reticle at multiple times during the scanning process, and perform, based on the deformation of the reticle at the multiple times, one or more adjustments of one or more components of the exposure tool during the scanning process.