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Infrared sensor with front side bandpass filter and vacuum cavity

IP.com Disclosure Number: IPCOM000187584D
Publication Date: 2009-Sep-11
Document File: 7 page(s) / 907K

Publishing Venue

The IP.com Prior Art Database

Abstract

An infrared sensor comprises a vacuum cavity (28) with a temperature sensor (4) located therein. An infrared filter plate (19) is located at a distance from and above the temperature sensor (4) by means of a spacer (20). The filter plate forms the top wall of the vacuum cavity (28). An additional seal layer (29) can be provided for sealing spacer (20) if spacer (20) not gas-tight. This design dispenses with a separate cap between the vacuum cavity (28) and the filter plate (19), which allows to manufacture the device more easily.

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Infrared sensor with front side bandpass filter and vacuum cavity

Abstract

  An infrared sensor comprises a vacuum cavity (28) with a temperature sensor (4) located therein. An infrared filter plate (19) is located at a distance from and above the temperature sensor (4) by means of a spacer (20). The filter plate forms the top wall of the vacuum cavity (28). An additional seal layer (29) can be provided for sealing spacer (20) if spacer (20) not gas-tight. This design dispenses with a separate cap between the vacuum cavity (28) and the filter plate (19), which allows to manufacture the device more easily.

  The invention relates to an infrared sensor with a temperature sensor arranged on a membrane in a vacuum cavity and with an infrared bandpass filter, as well as to a manufacturing method of such a sensor.

  Infrared sensors for measuring radiation in the spectral range between 800 nm and 20 m have a variety of applications, such as for contact-less temperature measurement as well as infrared spectroscopy.

  A sensor of this type is described in DE 10 2004 002 163. It comprises a temperature sensor arranged on a membrane in a vacuum cavity. The lid of the vacuum cavity is formed by a cap of silicon, which is transparent in the infrared spectral range. A bandpass filter is mounted to the top of this cap. Infrared light passing through the bandpass filter and the cap reaches the temperature sensor and heats it up, which allows to measure the amount of light. Placing the temperature sensor in the vacuum cavity provides good thermal insulation, which increases the sensitivity of the device.

  The problem to be solved by the present invention is to provide a sensor of this type that is easier to manufacture as well as a corresponding manufacturing method.

This problem is solved by the sensor and the method according to the independent claims.

  Accordingly, the filter plate forms the top wall of the vacuum cavity. Hence, this design dispenses with a separate cap between the cavity and the filter plate, which allows to manufacture the device more easily.

  A spacer can be provided between the top side of the substrate and the filter plate in order to keep the filter plate at the desired distance from the temperature sensor. Advantageously, the spacer is made of a material different from the filter plate, such as it can be optimized for its function.

  In particular, the spacer can be made from solder or glass frit, which allows to form a gas-tight seal between the substrate and the filter plate. Alternatively, the spacer may form a non-gas-tight connection, which is easier to manufacture. In that case, a further gas-tight seal layer covering at least part of the exterior of the filter plate, spacer and substrate can be provided for sealing the vacuum cavity.

  Other advantageous embodiments are described in the dependent claims as...