参比场效应晶体管(REFET)及 其与ISFET集成化的研究

本文介绍为实现带有参比电极的ISFET测量探头微型化而研制成的一种新型探头。采用等离子聚合方法在ISFET敏感栅上覆盖一层聚苯烯薄膜(PPS),使其成为对H~+不敏感的参比场效应晶体管(REFET)。而后采用IC艺,将ISFET,REFET和伪参比电极集成化,得到可用于微量溶液测量的微型探头,将探头中的ISFET和REFET按差分对管方式连接于差放线路中,由于两管对溶液中pH值响应不同,可输出随pH值变化的差模信号。研制的REFET在pH4～pH11范围内几乎无响应,表明了PPS膜具有较少的表面态及良好的H~+掩蔽性。用集成化探头测量pH值,灵敏度可达55mV/pH。

The Investigation of Reference Field Effect Transistor (REFET) and Integratization With ISFET

In order to realize miniaturization of ISFET with reference eletrode,a new measurement probe has been investigated. By means of plasma polymerization, the gate of one of the field effect transistors is coated with the polystyrene film (PPS) to form a refeence field effect transistor (REFET).The integrated ISFET, REFET and pseudoreference eletrode are obtained by IC technology for the analysis of small amount of solution. The differential ISFET/REFET pair on the probe are connected to differential amplifier circuit. The output differential signal varies with the pH value of solution because the pH response of ISFET is different from REFET's. As a result, the REFET has almost no pH response in the range pH4 to pH11. It has shown that PPS film is an ion-blocked membrane with low surface site density. The sensitivity of integrated probe to pH is 55mV/pH.