Wafer Stage Interferometer Thermal Expansion Stabilization

The patent applies the inert atmosphere principle by introducing a temperature-controlled gas flow environment around the interferometer optical path. A gas supply unit provides temperature-controlled gas (typically nitrogen or clean air) that flows along the measurement beam path, creating a stable, isolated atmosphere that prevents refractive index fluctuations caused by ambient temperature variations, dust, and humidity. This effectively creates an 'inert' measurement environment that eliminates the harmful effects of ambient gas variations.

The patent applies parameter changes by actively controlling the temperature of the gas in the optical path. A temperature control unit maintains the gas temperature within a predetermined range (e.g., ±0.1°C), thereby stabilizing the refractive index of the gas. By changing and controlling the temperature parameter of the ambient gas, the system eliminates refractive index fluctuations that would otherwise degrade measurement precision.

The patent applies the inert atmosphere principle by creating a controlled gas flow environment that remains stable even during high-speed stage movement. The gas supply unit continuously provides temperature-controlled gas that follows the movement of the stage, maintaining a stable refractive index environment. This isolated atmosphere prevents turbulence-induced measurement errors while allowing the stage to operate at high speeds for improved productivity.

The patent applies continuity of useful action by maintaining continuous gas flow along the optical path during stage movement. The gas supply operates continuously rather than intermittently, ensuring that the stabilizing gas environment is always present regardless of stage position or speed. This continuous provision of controlled atmosphere ensures uninterrupted high-precision measurement throughout the entire scanning process.

The patent applies local quality by providing temperature control specifically in the region where it is most needed—along the interferometer optical path. Rather than controlling the temperature of the entire chamber or environment, the system directs temperature-controlled gas only along the measurement beam path. This localized approach achieves interferometer stability with minimal system complexity, as only the critical measurement region receives active temperature control.

The patent applies the intermediary principle by introducing temperature-controlled gas as a mediator between the ambient environment and the interferometer optical path. This controlled gas acts as an intermediate layer that buffers the interferometer from ambient temperature fluctuations and turbulence. The intermediary gas flow absorbs the harmful effects of the external environment while allowing the interferometer to operate in a stable, controlled atmosphere.

The patent applies local quality by providing temperature control only along the specific region where the optical path exists, rather than enclosing the entire interferometer system or chamber. The temperature-controlled gas flow is directed precisely along the measurement beam path, creating thermal stability only where needed. This localized thermal management achieves the desired temperature stability with minimal structural additions, avoiding the complexity of full enclosure systems.

The patent applies pneumatics by using controlled gas flow to achieve temperature stability in the optical path. Instead of using solid enclosures or thermal insulation structures, the system employs a flow of temperature-controlled gas to actively regulate the thermal environment. This pneumatic approach provides dynamic temperature control with simpler, more flexible infrastructure compared to rigid structural enclosures, reducing device complexity while maintaining thermal stability.