Osaka, Japan - Panasonic Corporation has developed a manufacturable technology to drastically improve the device performance fabricated on silicon (Si) wafers by leveraging the unique feature of a phononic crystal structure*2, which can break the classical limitation of heat insulation property of solids*3. By introducing this technology to a thermal-type far infrared sensor, heat loss from the infrared-receiving section was reduced approximately to 1/10 of the initial sensor without the phononic crystal structure. As a result, infrared detection sensitivity was improved nearly by a factor of 10 in the sensors with phononic crystals. Panasonic presented this world's first research result on phononic far infrared sensors as an invited talk at SPIE Defense + Commercial Sensing 2021, which is one of the five major conferences of the SPIE (the international society for optics and photonics) in the fields of optics, photonics, and image engineering.
In the AI and IoT era, electronic devices tend to be packaged smaller and in higher density than ever. Increase in hot spots and unexpected heat flow in these devices have been a major concern as they can easily disturb the device performances. Therefore, development of an innovative thermal management technology is highly demanded for next generation microelectronic devices.
Recent studies have revealed that the classical limitation of thermal insulation performance of solids can be broken in an artificial structure with nanometer-scale periodic elastic continuum. Such artificial periodic structures are called phononic crystals, which allow for manipulating the propagation of phonons that dominate the thermal properties of semiconductors. However, extremely fine nanostructure patterns in the order of sub-50 nm are necessary to maximize the thermal insulation performance of phononic crystals. This feature made it difficult to employ the standard microfabrication tools used in conventional semiconductor foundries, which had hindered the practical leveraging of the unique feature of phononic crystals to electronic devices.
Panasonic developed a technology to fabricate phononic crystal structures in which the diameter and the period of pores are precisely controlled in the order of several tens of nanometers. The technology developed here is applicable to mass production on Si wafers. This newly developed technology enables the company to enhance the thermal insulation perfomance of Si thin films by a factor of ten. Panasonic has adopted this technology to Si supporting legs of infrared sensors (Fig. 1) to significantly improve the thermal insulation performance and to incerase the temperature rise of the infrared-receiving section upon infrared absorption (Fig. 2). This eventually led to improvement of the infrared detection sensitivity by a factor of ten (Fig. 3).
Utilizing this technology, Panasonic will provide new thermography solutions with higher temperature resolutions and innovative thermal management solutions in microelectronic devices through exploring the possibilities of collaboration with partners.