Alignment Mark Evaluation System for Semiconductor Exposure
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Solution Overview
Problem
Current methods for evaluating alignment marks in semiconductor exposure processes are inefficient and can damage photomasks, leading to reduced exposure stability and accuracy between wafers and wafer lots.
Innovation Solution
An alignment mark evaluation method and system that sets a process step code as an evaluation code to automatically enable the alignment mark evaluation step, allowing remote operation and skipping of photomask loading steps, thereby improving efficiency and extending mask service life.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a dedicated alignment mark evaluation machine is used, then measurement precision is improved, but device complexity and loss of time increase
Solution Approach 1:
The exposure machine is designed to perform both its primary exposure function and alignment mark evaluation function using the same optical system and sensors. The control system automatically switches between modes based on process step codes, eliminating the need for a separate dedicated evaluation machine while maintaining measurement precision through the high-quality exposure optics.
2Measurement precision
If photomask loading step is included in alignment mark evaluation, then measurement accuracy is maintained, but loss of time and device complexity increase
Solution Approach 1:
The system dynamically adjusts the evaluation process based on the process step code. When an evaluation code is detected, the system automatically modifies the process flow to skip photomask loading while switching to evaluation mode. This dynamic adaptation allows the system to maintain accuracy when needed while reducing time consumption during evaluation cycles.
Solution Approach 2:
The photomask loading step is extracted and conditionally removed from the evaluation process. The control system identifies evaluation codes and automatically excludes the photomask loading operation, keeping only the essential alignment mark detection and evaluation steps, thereby reducing cycle time without compromising evaluation quality.
3Reliability
If photomask is loaded during alignment mark evaluation, then measurement reliability is maintained, but photomask service life decreases
Solution Approach 1:
The system takes preliminary action by detecting the evaluation code before photomask loading occurs. Upon detection, it proactively prevents photomask loading by switching to evaluation mode, thereby avoiding unnecessary photomask usage and extending its service life while maintaining exposure stability through the dedicated evaluation process.
4Ease of operation
If automatic process step code recognition is implemented, then ease of operation is improved, but device complexity increases
Solution Approach 1:
The control system automatically recognizes evaluation codes from process step codes and self-manages the switching between exposure and evaluation modes. This self-service capability eliminates the need for manual intervention or complex external control systems, improving ease of operation while keeping the added complexity minimal and integrated within the existing control architecture.
Data Source
AI summary
Embodiments of the present disclosure provide an alignment mark evaluation method and an alignment mark evaluation system. The alignment mark evaluation method includes: setting a process step code of a wafer with an alignment mark to be evaluated as an evaluation code; obtaining a current process step code of the wafer; if it is detected that the current process step code is the evaluation code, switching a step to be executed to an alignment mark evaluation step; and executing the alignment mark evaluation step to evaluate the alignment mark to be evaluated.