Bulk silicon micromachining method for forming mems thermopile detector cavity structure

Abstract

The invention provides a micro machining method for bulk silicon for forming a cavity structure of an MEMS (micro-electromechanical systems) thermopile detector. The method comprises the following steps of: providing a silicon substrate, growing a silica membrane on the silicon substrate in a thermal oxidation manner, and forming a thermopile area and an infrared absorption area on the silica membrane. A thermal nodal area is arranged at one end of the thermopile area, close to the infrared absorption area, and a cold nodal area is arranged at the other end of the thermopile area, far away from the infrared absorption area. A silicon nitride and silica compound membrane structure is deposited on a thermopile structure layer, and a corrosion opening is formed in a compound membrane through photoetching. A release channel of the thermopile structure is formed by the corrosion opening. Through the release channel, a superficial layer on the surface of the bulk silicon is corroded by using an isotropy corrosion method so as to form a thin cavity of the superficial layer of the bulk silicon, and a bulk silicon deep layer below the thin cavity is corroded by using an anisotropy corrosion method so as to form a regular smooth ladder-shaped cavity structure, and therefore, the cavity structure in the bulk silicon is finally formed. The cavity structure formed by using the method has a regular and smooth inner surface and is good in structure symmetry.

Description

technical field [0001] The invention relates to a bulk silicon micromachining technology for forming a MEMS cavity structure, which is especially suitable for the manufacture of thermopile infrared detectors. Background technique [0002] Infrared detectors are one of the most critical components in an infrared system. The thermopile infrared detector is an uncooled infrared detector developed earlier. Its working principle is based on the Seebeck effect, in which a temperature difference between two different electrical conductors or semiconductor materials results in a voltage difference between the two materials. Because thermopile infrared detectors have the advantages of small size, can work at room temperature, wide-spectrum infrared radiation response, can detect constant radiation, and low manufacturing cost, they are widely used in safety monitoring, medical treatment, life detection, etc. [0003] At present, the thermopile structure generally adopts a thin film ...

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