Lithography Stage Alignment Using Broadband Optical Tilt Detection
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Solution Overview
Problem
Existing lithography processes face challenges in accurately aligning semiconductor substrates during the patterning process, leading to inefficiencies and reduced resolution in the production of integrated circuits.
Innovation Solution
A lithography apparatus equipped with a light receiver structure and a light source system that uses broadband alignment light to detect substrate stage tilt and shift, employing a multi-channel color receiver and a controller to adjust alignment, enabling precise positioning through machine learning algorithms.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional alignment methods are used, then alignment can be performed, but alignment accuracy is insufficient and alignment time is excessive
Solution Approach 1:
The patent replaces traditional mechanical alignment systems with an optical detection system. A light source emits light through a first objective lens onto the substrate, and a second objective lens collects the transmitted light to form an image on a detector. This optical system substitutes mechanical measurement methods, enabling non-contact, high-precision alignment detection that simultaneously improves accuracy and reduces time.
Solution Approach 2:
The patent creates an optical copy (image) of the substrate's alignment state through the objective lens system. The detector captures an image that represents the physical position and orientation of the substrate, allowing alignment verification without direct mechanical contact. This copying mechanism enables rapid, repeated measurements that improve both speed and precision.
2Reliability
If alignment verification is performed, then alignment status can be confirmed, but the process becomes more complex
Solution Approach 1:
The patent implements a multi-functional alignment system where the same optical path and detector serve multiple purposes: detecting substrate position, orientation, and alignment status. The light source and lens system can verify alignment across different target portions and layers, providing universal verification capability that improves reliability without proportionally increasing complexity.
Solution Approach 2:
The alignment verification system is integrated into the lithography apparatus itself, allowing the machine to self-verify and self-adjust alignment. The detector provides feedback that can be used by the control system to automatically correct misalignment, making the system self-sufficient and reducing the need for external verification equipment.
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
Enhances alignment accuracy, reduces alignment time, and improves resolution by verifying correct alignment status and adjusting substrate position automatically, thereby improving the efficiency of lithography processes.
Implementation Method 1
a light source configured to provide an alignment light toward the second region of the substrate stage; a light receiver structure over the second region of the substrate stage
Data Source
AI summary
A lithography apparatus includes a substrate stage having a first region configured to hold a semiconductor substrate and a second region surrounding the first region; a light receiver structure over the second region of the substrate stage; a light source configured to provide an alignment light toward the second region of the substrate stage; a mask stage configured to secure a mask; and an optical module configured to direct an exposure light from the mask onto the semiconductor substrate.