Gas flowmeter and manufacturing method thereof

摘要

A gas flowmeter capable of reducing a secular change comprises a silicon semiconductor substrate formed with a cavity and a heat element formed above the cavity of the semiconductor substrate by way of an insulating film. The heat element is a silicon (Si) semiconductor thin film impurity-doped at high concentration. Stoichiometrically stable silicon nitride (Si₃N₄) thin films as barrier layers which less permeate and less absorb hydrogen in the heat generating temperature range of the heat element are formed above and below the silicon (Si) semiconductor thin film.