Structure of a micro-Pirani sensor and its temperature compensation method

摘要

A new construction of a low-pressure measuring device having a good design of the temperature compensation and stabilisation is presented. The construction comprises a suspended plate which is produced by means of a micro-machining technique and a thermally sensitive element installed on the suspended plate. The suspended plate has a number of suspended arms extending outwards, in order to hold the suspended plate, for good thermal insulation, in a cavity in a semiconductor substrate. The surface of the suspended plate and the length and breadth of the arm serving for its suspension are at a specific ratio to each other in order to achieve an optimum sensitivity. A dummy resistor for temperature compensation consists of a series connection of a constant resistor having a temperature coefficient of virtually zero and of the thermally sensitive elements in a special ratio. In addition, the low-pressure measuring device overlaps a temperature-controlled thermoelectric cooling element and is covered by a thermally protective shield, so that the temperatures on and around the suspended plate can be kept stable.