Schottky Diode Characteristics Of Rf Cmos Process And Modeling Research

With the fast growth in the radio frequency (RF) wireless communications market and the development in the mobile communication technology, the demand for high performance RF/MW devices is rising. Schottky barrier diode is one of the important components in the RF circuit. It is a kind of majority carrier device, using the contact barrier formed between metal and semiconductor to work. It has no charge stored effect. It has the advantages of high operating frequency, high switching speed and low forward voltage drop, compared with PN junction diode. Due to these advantages, it has been used widely for RF signal rectification, mixer and low voltage reference circuits. Integrating the Schottky diode into CMOS RFIC is very important to increase high frequency performance as well as to decrease the production cost and chip size.When the circuit is operating in the RF range, the simple discrete schottky diode model is insufficient to describe the integrated Si Schottky diode characteristics due to the bulk effects introduced by the lossy Si substrate as well as the distributed effects of the lateral diode region. Base on the DC and RF measured data, a new and accurate Schottky diode model considering the bulk and distributed effects is introduced. It is shown that the suggested novel model fits measurement data very well for different voltage biases over the wide range of frequency from 50MHz to 8.5GHz and can be used well in circuit design.The following work is included in this thesis:(1) Design and fabricate Schottky diodes in SMIC 0.18μm RF CMOS process. Inorder to improve the performance of Schottky diodes, we make a deep research on the physical structure of Schottky diode and optimize Schottky diodes' layout.(2) Analyze and summarize the factors which effect Schottky diode's characteristicsbased on the measurement results, such as the distance between Schottky contact and ohmic contact in the N well, the shape of Schottky contact, area of Schottky contact and guard ring.(3) Base on the measured data, a accurate Schottky diode model considering thebulk and distributed effects is introduced in this thesis. It is shown that the new model can fit well with the measured data in the range of frequency from 50MHz to 8.5GHz. At the same time, a parameter extraction method is also introduced in detail in this thesis.