CMUTs with high-K atomic layer deposition dielectric material insulation layer.
CMUTs with high-K atomic layer deposition dielectric material insulation layer.
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DOI：
10.1109/tuffc.2014.006481
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发表时间：
2014-12
期刊：
影响因子：
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通讯作者：
Degertekin F
中科院分区：
文献类型：
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作者：
Xu T;Tekes C;Degertekin F
研究了使用高介电常数原子层沉积（ALD）材料作为电容式微机械超声换能器（CMUT）的绝缘层材料。使用一个简单的平行板模型的绝缘层材料和厚度对CMUT性能的影响进行了评估。该模型表明，高介电常数和电击穿强度是重要的电介质材料，并可以实现显着的性能改善，特别是作为真空间隙厚度减小。特别地，ALD氧化铪（HfO 2）被评估并用作对用于通过低温互补金属氧化物半导体晶体管兼容的牺牲释放方法制造的CMUT的等离子体增强化学气相沉积（PECVD）氮化硅（SixNy）的改进。ALD HfO 2的相关性能，如介电常数和击穿强度的特点，以进一步指导CMUT设计。平行制造的测试CMUT与50 nm的间隙和16.5 MHz的中心频率进行实验，以测量和比较压力输出和接收灵敏度为200 nm的PECVD SixNy和100 nm的HfO 2绝缘层。这种特殊设计的结果显示，接收器输出改善了6 dB，崩溃电压降低了一半;而在发射模式下，需要一半的输入电压才能实现相同的最大输出压力。
Use of high-κ dielectric, atomic layer deposition (ALD) materials as an insulation layer material for capacitive micromachined ultrasonic transducers (CMUTs) is investigated. The effect of insulation layer material and thickness on CMUT performance is evaluated using a simple parallel plate model. The model shows that both high dielectric constant and the electrical breakdown strength are important for the dielectric material, and significant performance improvement can be achieved, especially as the vacuum gap thickness is reduced. In particular, ALD hafnium oxide (HfO2) is evaluated and used as an improvement over plasma-enhanced chemical vapor deposition (PECVD) silicon nitride (SixNy) for CMUTs fabricated by a low-temperature, complementary metal oxide semiconductor transistor-compatible, sacrificial release method. Relevant properties of ALD HfO2 such as dielectric constant and breakdown strength are characterized to further guide CMUT design. Experiments are performed on parallel fabricated test CMUTs with 50-nm gap and 16.5-MHz center frequency to measure and compare pressure output and receive sensitivity for 200-nm PECVD SixNy and 100-nm HfO2 insulation layers. Results for this particular design show a 6-dB improvement in receiver output with the collapse voltage reduced by one-half; while in transmit mode, half the input voltage is needed to achieve the same maximum output pressure.