Immersion Position Measuring Apparatus for Semiconductor Substrate Alignment
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Solution Overview
Problem
In the photolithography process for semiconductor manufacturing, achieving accurate positional alignment between substrates and photomasks is challenging due to stress-induced positional shifts in three-dimensional semiconductor structures, requiring precise position measurement to correct for distortion.
Innovation Solution
A position measuring apparatus comprising a substrate holding part, a projection part, a liquid supply system, an imaging system, and a control unit that uses illumination light, a liquid immersion system, and gas conduits to maintain a liquid layer between the substrate and projection part, allowing for high-resolution image capture and precise positional determination of circuit patterns on the substrate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a liquid layer is introduced between the substrate and projection part to improve measurement precision, then measurement precision is improved, but device complexity increases due to additional liquid supply and temperature control systems
Solution Approach 1:
A liquid layer is introduced as an intermediary medium between the substrate and projection part. This liquid layer serves multiple functions: it improves optical transmission for higher measurement precision, and simultaneously acts as a thermal medium to maintain substrate temperature stability, thereby reducing thermal deformation during measurement
Solution Approach 2:
The liquid layer performs multiple functions simultaneously: it acts as an optical medium to improve image quality and measurement precision, while also serving as a thermal regulation medium to maintain substrate temperature. This multi-functionality reduces the need for separate systems, partially offsetting the added complexity
2Area of stationary object
If the projection part is moved to measure different positions on the substrate, then measurement coverage is improved, but measurement time increases due to intermittent liquid retention requirements
Solution Approach 1:
The liquid supply operates periodically rather than continuously. The liquid is supplied to the space between substrate and projection part only when needed for measurement, and the system is designed to retain the liquid temporarily during projection part movement. This periodic action reduces overall liquid usage and allows faster positioning between measurements
Solution Approach 2:
The liquid retention characteristic is optimized dynamically - the liquid can be quickly supplied when the projection part is in position for measurement, and the system tolerates temporary liquid absence during rapid positioning movements. This dynamic approach allows the system to adapt liquid supply to the actual measurement needs, reducing unnecessary wait time
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 accurate and efficient positional measurement of semiconductor substrates, improving alignment accuracy and reducing measurement time while maintaining the substrate's temperature stability, thus preventing deformation and maintaining measurement precision.
Implementation Method 1
a liquid supply part configured to supply liquid into a space between the substrate held on the substrate holding part and the projection part
Implementation Method 2
to transmit reflected light from the substrate, of the illumination light radiated on the substrate
Implementation Method 3
transmit reflected light from the substrate, of the illumination light radiated on the substrate
Data Source
AI summary
According to one embodiment, a position measuring apparatus includes a substrate holding part, a projection part, a liquid supply part, an imaging part, a position measuring part, and a control unit. The substrate holding part is configured to hold a substrate including at least part of a circuit pattern. The projection part is configured to irradiate the substrate held on the substrate holding part with illumination light, and to transmit reflected light from the substrate, of the illumination light radiated on the substrate. The liquid supply part is configured to supply a liquid into a space between the substrate held on the substrate holding part and the projection part. The imaging part is configured to receive the reflected light transmitted through the projection part, and to generate an image signal based on the reflected light. The position measuring part is configured to obtain positional information on a position of the substrate holding part. The control unit is configured to determine a coordinate position of the at least part of a circuit pattern in the substrate, on a basis of the positional information and the image signal.