Focal plane array and method for manufacturing the same
a technology of focal plane array and manufacturing method, which is applied in the direction of photovoltaics, electrical appliances, solid-state devices, etc., can solve the problems of limiting the amount of sensing material available and limiting the performance of imaging devices, so as to maximise maximise the total area of active sensing material , the effect of maximising the active sensing area availabl
Inactive Publication Date: 2015-07-23
SENSONOR
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Benefits of technology
The patent describes a new method for making arrays of pixels in a way that maximizes the area of the active sensing material. This is done by using a two-level structure that allows for the formation of multiple vacuum-encapsulated focal plane arrays on a single substrate. This method also allows for the use of high performance crystalline materials, which could not previously be used due to the layer-wise construction of the pixels required. Overall, the method increases the amount of sensing material that can be used in the array, resulting in improved performance and more efficient manufacturing.
Problems solved by technology
However, legs arranged in this way occupy valuable space within the focal plane array, which limits the amount of sensing material available and hence limits the performance of the imaging device.
Method used
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[0024]FIG. 1 shows a plan view of a focal plane array (FPA) 1, according to the present invention, before sealing, the FPA comprising a plurality of pixels 2 arranged in an array. The focal plane array 1 of this example is suitable for a thermal imaging device and hence each pixel 2 is a bolometer pixel comprising sensing material 3, which in this example consists of a thermistor built as a layer stack of for example, Si and SiGe with contacting and buffer layers, as will be described in detail below.
[0025]The material for the thermistor 3 is chosen on the basis that it has a strong temperature dependent resistivity. Energy absorbed in the layers generates heat, resulting in a measurable change in the thermistor 3 resistance. Absorption of the infra-red (IR) waves 6 is enhanced by the introduction of an absorber layer 4 positioned on an upper surface of the thermistor 3 at a wavelength optimised distance from a reflector layer 5 that is deposited on the reverse side of the thermisto...
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A method of forming a focal plane array by: preparing a first wafer having sensing material provided on a surface, which is covered by a sacrificial layer; preparing a second wafer including read-out integrated circuit and a contact pad, which is covered by another sacrificial layer into which are formed support legs in contact with the contact pad, the support legs being covered with a further sacrificial layer; bonding the sacrificial layers of the first and second wafers together such that the sensing material is transferred from the first wafer to the second wafer when a sacrificial bulk layer of the first wafer is removed; defining a pixel in the sensing material and forming a conductive via through the pixel for providing a connection between an uppermost surface of the pixel and the supporting legs; and removing the sacrificial layers to release the pixel, with the supporting legs underneath it.
Description
RELATED APPLICATIONS[0001]This application is a continuation of a national stage application No. 13 / 582,103 filed Oct. 4, 2012, under 35 U.S.C. §371, of International Application No. PCT / EP2011 / 053049, filed Mar. 1, 2011, which claims priority to European Application No. 10155250.3, filed Mar. 2, 2010, with above-identified applications incorporated by reference herein in their entireties.FIELD OF THE INVENTION[0002]The present invention relates to the manufacture of focal plane arrays and, in particular, the manufacture of a focal plane array for use in a thermal imaging device, using transfer bonding of sensing material.BACKGROUND OF THE INVENTION[0003]The resolution of an imaging device is very much dependent on the number of pixels provided in its focal plane array. The number of pixels is, in turn, limited by the dimensions of the focal plane array.[0004]In existing focal plane arrays, pixels are generally supported by legs that extend from opposing sides. However, legs arrange...
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IPC IPC(8): H01L27/146
CPCH01L27/1467H01L27/14636H01L27/14632H01L27/14685H01L27/14687H01L27/14625H01L27/14683
Inventor LAPADATU, ADRIANAKITTILSLAND, GJERMUND
Owner SENSONOR