principle
Digital vacuum sensors integrate physical effects with electronic technology to convert pressure changes in vacuum environments into measurable electrical signals, ultimately displaying vacuum degree values in digital form. The core principles can be divided into two categories:
Piezoresistive: Utilizing the piezoresistive effect of semiconductor materials, when gas molecules in a vacuum environment collide with pressure-sensitive components (such as silicon membranes), the membrane deforms, causing a change in resistance. This is converted into an electrical signal through a Wheatstone bridge, and then nonlinear correction and temperature compensation are performed through an intelligent chip to output a linear standard signal. For example, a certain model of sensor has a resolution of 0.1Pa in the range of 0.1-10 ⁵ Pa and can capture micrometer level deformation on the wafer surface.
Capacitive: The silicon diaphragm acts as a sensitive element and swells upwards under atmospheric pressure. The degree of bulging changes with the vacuum degree, resulting in a change in the distance between the two electrode plates of the capacitor and a corresponding change in the capacitance value. By measuring the circuit and converting the capacitance value into a voltage or frequency signal, the vacuum degree can be calculated. For example, a certain model of sensor has a resolution of 2.0Pa within the range of 10 ³ -10 ⁵ Pa, ensuring a coating thickness uniformity of<1%.
selection
The selection should consider the following factors comprehensively:
Range and accuracy: Choose the appropriate range according to the application scenario, such as thermal conductivity for low vacuum (1000Pa-10Pa), piezoresistive for medium vacuum (10Pa-10 ⁻³ Pa), and capacitive or magnetic levitation for high vacuum (10 ⁻³ Pa-10 ⁻⁹ Pa). For scenarios with high precision requirements, such as semiconductor manufacturing, sensors with an error of less than 1% should be selected.
Environmental adaptability: If there is a large change in environmental temperature, it is necessary to choose a model with temperature compensation function; If there are acidic or alkaline gases present, corrosion-resistant materials should be selected.
Response time and stability: For dynamic pressure monitoring scenarios, sensors with fast response times (such as milliseconds) should be selected; For scenarios that require high long-term stability, models with strong anti drift capabilities should be selected.
application
Digital vacuum sensors are widely used in multiple fields:
Semiconductor manufacturing: Real time monitoring of pressure changes inside the vacuum chamber to ensure the accuracy of processes such as photolithography and etching.
Vacuum coating: Accurately control the vacuum degree to avoid pinholes or cracks in the coating layer.
Vacuum metallurgy: Monitor the vacuum degassing and refining process of molten steel outside the furnace, optimize process parameters.
Research experiment: Monitor gas adsorption/desorption processes in high vacuum environments to provide data support for the development of new materials.