Lithographic Field Alignment via Relative Positional Mapping
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Solution Overview
Problem
Current lithographic methods face challenges in accurately determining the position of each field on a substrate, which can lead to misalignment of successively applied layers, affecting the functionality of devices like integrated circuits, and this process is time-consuming, reducing throughput.
Innovation Solution
A method that uses an alignment apparatus to determine relative positional relationships between applied fields on a substrate, obtaining absolute positional relationships between the fields and the lithographic apparatus, allowing for precise alignment of subsequent fields without relying solely on alignment marks, thereby improving overlay accuracy and reducing processing time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the position of each field is determined using alignment apparatus in the lithographic apparatus, then manufacturing precision is improved, but productivity deteriorates due to time-consuming measurements
Solution Approach 1:
The patent segments the field position determination process into two distinct phases: a lithography phase where fields are exposed on the substrate, and a metrology phase where the positions of these fields are measured using a separate measurement system. This segmentation allows the lithographic apparatus to maintain high throughput while the metrology system independently performs precise measurements, resolving the contradiction between measurement precision and productivity.
Solution Approach 2:
The patent introduces alignment marks as intermediary features that are exposed alongside the actual fields. These alignment marks serve as measurable references that encode positional information about the fields without requiring direct measurement of the fields themselves. The metrology system measures the positions of these alignment marks to infer field positions, enabling precise overlay determination without time-consuming direct field measurements during lithography operations.
2Ease of operation
If alignment marks are used to determine substrate position changes, then ease of operation is improved, but measurement precision deteriorates as field positions are not directly measured
Solution Approach 1:
The patent creates a copy of the field position information through the exposure of alignment marks at known relative positions to the fields. These alignment marks serve as measurable copies that preserve the positional relationships of the fields. By measuring the positions of these copied alignment marks in the metrology system, the actual field positions can be accurately determined without directly measuring the fields during lithography, thus maintaining both ease of operation and measurement precision.
Data Source
AI summary
A method includes determining relative positional relationships between applied fields on a substrate, one of the applied fields including a first field; in a lithographic apparatus, using an alignment apparatus to obtain at least one absolute positional relationship between the position of at least the first field of the substrate and a part of the lithographic apparatus; and determining an absolute positional relationship between at least one field, other than the first field, and a part of the lithographic apparatus using the relative positional relationships and the at least one obtained absolute relationship.