Surface Position Detection Apparatus Polarization Displacement Compensation
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Solution Overview
Problem
Conventional surface position detection apparatuses in projection exposure systems suffer from detection errors due to relative displacement of polarization components in light beams passing through reflection surfaces, especially when the surface of a photosensitive substrate is coated with a resist layer, affecting the accuracy of surface position detection and pattern alignment.
Innovation Solution
Incorporating a displacement offset member, such as a Nomarski prism or beam displacer, in the pupil space of the projection or light receiving systems to offset relative displacement of polarization components, ensuring accurate detection of surface position without interference from polarization changes caused by the resist layer thickness variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If diagonal incident light is used to improve surface position detection accuracy, then detection precision is improved, but polarization components become displaced causing detection errors
Solution Approach 1:
A compensation prism is introduced as an intermediary optical element to counteract the polarization component displacement caused by the diagonal incident light. The compensation prism receives the light beam after it reflects from the wafer surface and adjusts the polarization components to cancel out the displacement effect, thereby maintaining both high detection accuracy and reliability
Solution Approach 2:
The compensation prism is designed to apply a preliminary counteracting action to the polarization components before they cause detection errors. By pre-adjusting the polarization state in the opposite direction of the expected displacement, the system prevents the harmful effect from occurring in the first place
2Device complexity
If light passes through rhombic prism reflection surfaces to maintain optical path, then optical system structure is maintained, but relative displacement of polarization components occurs causing pattern blur
Solution Approach 1:
The compensation prism acts as a mediator between the rhombic prism and the detected surface, correcting the polarization component displacement without requiring changes to the existing rhombic prism structure. This maintains the optical system complexity while improving the pattern alignment precision
Solution Approach 2:
The compensation prism changes the polarization state parameter of the light beam to counteract the displacement effect. By adjusting the polarization parameters in the opposite direction, the system maintains the structural integrity of the rhombic prism while achieving precise pattern alignment
3Adaptability or versatility
If resist layer thickness varies on wafer surface, then coating process flexibility is improved, but light reflectivity changes causing detection errors
Solution Approach 1:
The compensation prism dynamically addresses reflectivity changes by adjusting the polarization state of the incident light. This parameter change compensates for the varying reflectivity caused by different resist layer thicknesses, maintaining detection accuracy while allowing coating process flexibility
Solution Approach 2:
The system uses the polarization compensation mechanism as a feedback loop to continuously adjust for reflectivity variations. By monitoring and compensating for polarization displacement in real-time, the system maintains accurate surface position detection despite variations in resist layer thickness
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 high-precision detection of surface position and alignment of pattern surfaces with the projection optical system, reducing errors and ensuring precise manufacturing of devices like semiconductor and liquid crystal display devices.
Implementation Method 1
relative displacement of polarization components in a light beam passing through the first reflection surface of the projection system and the second reflection surface of the light receiving system
Implementation Method 2
A surface position detection apparatus that detects a surface position using diagonal incident light
Implementation Method 3
a light receiving system which receives a light beam reflected by the detected surface
Data Source
AI summary
A surface position detection apparatus capable of highly precisely detecting the surface position of a surface to be detected without substantially being affected by relative positional displacement due to a polarization component occurring in a light flux having passed through a reflective surface. In the apparatus, a projection system has a projection side prism member having first reflective surfaces, and a light receiving system has a light receiving prism member having second reflective surfaces arranged in correspondence with the projection side prism member. The surface position detection apparatus further has a member for compensating relative positional displacement due to a polarization component of a light flux having passed through the first and second reflective surfaces.