Phase-Change Wafer Sensor for Precise Alignment Feedback
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Solution Overview
Problem
Semiconductor substrate processing faces challenges with poor alignment due to mechanical errors accumulation, leading to yield deterioration, necessitating precise alignment evaluation and control in operations like photolithography and wafer testing.
Innovation Solution
A wafer sensor with a phase change material layer and a wafer alignment system that includes a blocking layer, reflective layer, and metal antennas, utilizing a measurement station to measure changes in the phase change material layer for alignment adjustment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional alignment methods are used without phase change material, then the structure is simpler, but alignment precision deteriorates due to mechanical errors accumulation
Solution Approach 1:
The patent utilizes phase change material (PCM) that transitions between amorphous and crystalline states in response to thermal energy from the chuck. This phase transition creates detectable optical property changes that enable precise alignment measurement. The PCM layer transforms mechanical/thermal information into optical signals that can be measured with high precision, resolving the contradiction between measurement precision and device complexity.
Solution Approach 2:
The phase change material exhibits changes in optical properties (reflectivity, absorption) when transitioning between phases. These optical property changes serve as detectable signals for alignment measurement. The measurement station detects these optical changes to determine alignment accuracy, enabling precise measurement without requiring complex mechanical alignment systems.
2Productivity
If alignment is not adjusted based on measurement, then the process is faster, but yield deteriorates due to poor alignment
Solution Approach 1:
The system implements a feedback loop where the measurement station continuously monitors alignment using the PCM layer's phase transition signals. The transfer device receives alignment information and adjusts the substrate position accordingly. This closed-loop feedback system ensures high alignment reliability while maintaining productivity through automated real-time adjustment rather than manual intervention.
Solution Approach 2:
The patent replaces complex mechanical alignment systems with an optical detection system based on PCM phase transitions. Instead of relying on mechanical precision and manual adjustment, the system uses optical properties of the PCM to detect and signal alignment status, which is then corrected by the transfer device. This substitution maintains reliability while improving processing speed through automation.
3Adaptability or versatility
If the wafer sensor cannot be reset, then repeated use is limited, but manufacturing cost increases due to single-use sensors
Solution Approach 1:
The phase change material can be repeatedly cycled between amorphous and crystalline phases through periodic thermal treatment. After use, the PCM layer is reset by heating to crystallize it uniformly, preparing it for the next measurement cycle. This periodic reset capability enables the sensor to be reused multiple times, reducing manufacturing costs while maintaining measurement quality across repeated uses.
Solution Approach 2:
Instead of discarding the sensor after single use, the system recovers the PCM layer's measurement capability through thermal reset. The chuck or separate heating mechanism recrystallizes the PCM, restoring its uniform optical properties and enabling repeated use of the same sensor substrate. This recovery process eliminates the need for continuous sensor manufacturing and disposal.
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 precise alignment by detecting phase changes in the phase change material layer, enhancing alignment accuracy and allowing for repeated use through a reset operation, thereby improving yield in semiconductor manufacturing processes.
Implementation Method 1
heating, by the chuck, at least a portion of the phase change material layer to a crystallization temperature or greater
Implementation Method 2
heating, by the chuck, at least a portion of the phase change material layer to a crystallization temperature or greater
Implementation Method 3
a reflective layer on the blocking layer
Data Source
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AI summary
A wafer sensor includes a wafer substrate and a plurality of pixels on the wafer substrate, where each pixel of the plurality of pixels includes a blocking layer, a reflective layer on the blocking layer, a phase change material layer on the reflective layer, and a plurality of metal antennas on the phase change material layer.