A kind of compound electrode type pH sensor based on cmos technology and preparation method thereof

Abstract

The invention provides a composite electrode type pH sensor based on a CMOS (Complementary Metal Oxide Semiconductor) process and a preparation method of the pH sensor. The sensor comprises a substrate, a sensing detection area, a working electrode, a reference electrode, an electrode lead and a bonding pad. The working electrode is arranged above the sensing detection area, and the reference electrode is positioned inside the sensing detection area. The preparation method comprises the following steps: manufacturing a substrate from an alumina ceramics material; manufacturing a semiconductor substrate and a well region; manufacturing the reference electrode; manufacturing an isolation region and an electrode oxide layer; manufacturing a metal aluminum layer; manufacturing the working electrode; manufacturing the electrode lead; and manufacturing the bonding pad. The CMOS technology is adopted, and the reference electrode is manufactured inside the device, so that reference electrode is prevented from being interfered and influenced by an outside environment, and the stability of the reference electrode is improved. The sensor has the characteristics of high stability, high sensitivity, high repeatability and the like, is easy to integrate and miniaturize and suitable for in-situ measurement of pH of a soil cultivation matrix and other heterogeneous systems, and solves the pH measurement problem in case of less moisture content.

Description

technical field [0001] The invention belongs to the application field of electrochemical sensors, in particular to a composite electrode pH sensor based on CMOS technology and a preparation method thereof, which are used to realize the original pH value of heterogeneous systems such as soil with less water content and cultivation substrates. bit measurement. Background technique [0002] Soil and cultivation substrate are a mixture of minerals and organic matter, mainly solid particles, but there are certain gases and liquids in the gaps between solid particles, which belong to a heterogeneous system. Its complex composition and heterogeneous mixed state make the soil matrix exhibit many different physical and chemical properties. In addition, because part of the soil and the matrix itself are relatively loose, it will cause poor detection contact, resulting in poor adaptability to parameter detection, low detection sensitivity, large error, and poor stability. to difficul...

AI Technical Summary

Problems solved by technology

The structure of the ISFET is very similar to the MOSFET without the metal gate or the polysilicon gate. The pH sensor based on the ISFET also has great research progress, such as the patent application publication number CN 103472115A ion-sensitive field-effect transistor and its preparation method, which discloses an ion-sensitive field-effect transistor and its preparation method. Sensitive field effect transistors can effectively improve the accuracy and repeatability of measurement results, but it does not involve the in-situ measurement of the pH value of the heterogeneous system and the pH sensor of the all-solid-state composite electrode and its preparation method

Currently, pH_ISFET sensors use Si 3 N 4 、Al 2 o 3 、 Ta 2 o 5 etc. as sensitive materials, such as Shi Zhaoxia and Zhu Dazhong in the design and research of pH sensor integrated circuit based on 0.6μm CMOS process, using standard CMOS process to provide Si 3 N 4 As a hydrogen ion sensitive layer, the passivation layer has good sensitivity and linearity, but it can only be measured in a solution environment

Generally, the existing sensors of this type can only be used to detect the pH value of the solution, and an external reference electrode is required. The test process is cumbersome, and the sensor processing technology is relatively high, so it cannot be used in the detection of solid-state environments.

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