Centre for Electronics Frontiers, Zepler Institute for Photonics and Nanoelectronics, University of Southampton, Highfield Campus, University Road, Building 53 (Mountbatten), Southampton SO17 1BJ, UK.
Sensors (Basel). 2020 Jul 31;20(15):4294. doi: 10.3390/s20154294.
Surface acoustic wave (SAW) resonators are low cost devices that can operate wirelessly on a received radio frequency (RF) signal with no requirement for an additional power source. Multiple SAW resonators operating as transponders that form a wireless sensor network (WSN), often need to operate at tightly spaced, different frequencies inside the industrial, scientific and medical (ISM) bands. This requires nanometer precision in the design and fabrication processes. Here, we present results demonstrating a reliable and repeatable fabrication process that yields at least four arrays on a single 4-inch wafer. Each array consists of four single-port resonators with center frequencies allocated inside four different sub-bands that have less than 50 kHz bandwidth and quality factors exceeding 8000. We see promise of standard, low-cost photolithography techniques being used to fabricate multiple SAW resonators with different center resonances all inside the 433.05 MHz-434.79 MHz ISM band and a mere 100 kHz spacing. We achieved that by leveraging the intrinsic process variation of photolithography and the impact of the metallization ratio and metal thickness in rendering distinct resonant frequencies.
声表面波（SAW）谐振器是低成本器件，可在接收到的射频（RF）信号上无线运行，无需额外的电源。作为无线传感器网络（WSN）的转发器运行的多个 SAW 谐振器通常需要在工业、科学和医疗（ISM）频段内紧密间隔的不同频率下运行。这需要在设计和制造过程中具有纳米级精度。在这里，我们展示了可靠且可重复的制造工艺的结果，该工艺在单个 4 英寸晶圆上至少可以生产四个阵列。每个阵列由四个单端口谐振器组成，中心频率分配在四个不同的子带内，带宽小于 50 kHz，品质因数超过 8000。我们希望看到标准的低成本光刻技术能够用于制造多个中心频率不同的 SAW 谐振器，所有这些谐振器都位于 433.05 MHz-434.79 MHz ISM 频段内，并且仅相隔 100 kHz。我们通过利用光刻的固有工艺变化以及金属化比和金属厚度对呈现不同谐振频率的影响来实现这一目标。
