Schottky Diode Integration in CMOS Using Silicide Contacts
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Solution Overview
Problem
Integrating Schottky diodes into CMOS processed integrated circuit chips, such as those used in RFID tags, is challenging due to the difficulty in incorporating metal-semiconductor contacts within existing CMOS process flows, particularly in Front End Of Line (FEOL) wafer processing where metal use is restricted.
Innovation Solution
A Schottky diode is fabricated using standard CMOS processing techniques by forming a metal contact and a silicide contact on a semiconductor substrate with an active region bordered by an isolation region, allowing integration in middle or back end of line process flows, and utilizing a protection layer to manage silicidation and reduce leakage currents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If Schottky diodes are integrated using metal-semiconductor contacts in FEOL wafer processing, then low forward bias voltage is achieved, but metal use is restricted in existing CMOS process flows
Solution Approach 1:
A silicide contact layer is introduced as an intermediary between the metal contact and the semiconductor substrate. This silicide layer enables the formation of a Schottky barrier without requiring direct metal-semiconductor contact during FEOL processing, thus resolving the contradiction between achieving low forward bias voltage and compatibility with CMOS process restrictions on metal use.
2Adaptability or versatility
If standard CMOS processing techniques are used to fabricate Schottky diodes, then integration into existing circuits is enabled, but metal-semiconductor contact formation is difficult
Solution Approach 1:
The silicide contact formation process is merged with the existing CMOS processing flow, combining the benefits of standard CMOS fabrication with the electrical characteristics of Schottky contacts. This integration allows Schottky diodes to be fabricated using conventional CMOS tools and process steps, eliminating the need for separate metal-semiconductor contact formation processes.
3Use of energy by moving object
If Schottky diodes are fabricated with low Vf, then power efficiency is enhanced, but reverse leakage current may increase
Solution Approach 1:
The work function of the metal contact is optimized to achieve a balance between forward bias voltage and reverse leakage current. By carefully selecting metal materials with appropriate work functions and controlling the silicidation process parameters, the Schottky barrier height is tuned to provide low Vf for power efficiency while maintaining sufficient reverse breakdown voltage to minimize leakage.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enables the efficient integration of Schottky diodes into integrated circuits, reducing switch-on voltage and leakage currents, thus enhancing the power efficiency and operational range of RFID tags by allowing low values of forward bias voltage and minimizing reverse leakage.
Implementation Method 1
Schottky diodes, which typically include a metal-semiconductor junction, which forms the basis for the rectifying action of the diode
Implementation Method 2
forming a silicide contact also provided on said surface of said active region
Data Source
AI summary
An integrated circuit including a Schottky diode, and a method of making the same. The diode includes an active region bordered by an isolation region in a semiconductor substrate of the integrated circuits, a first electrode having a metal contact provided on a surface of the active region, and a second electrode having a silicide contact also provided on the surface of the active region.