MIS Contacts with Oxygen Vacancies for Low Resistivity
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Solution Overview
Problem
As semiconductor feature dimensions shrink, existing metal silicide contacts face challenges in achieving low resistivity, good adhesion, minimal reaction with SiO2, and thermal stability, especially for germanium-containing devices, while maintaining compatibility with advanced processing steps.
Innovation Solution
A method involving the formation of metal-insulator-semiconductor (MIS) contacts using a semiconductor substrate with a mixed oxide insulator film containing titanium oxide (TiO2) and additional metal oxides, where oxygen is scavenged from the TiO2 to create oxygen vacancies, and a metal-containing electrode layer is deposited and heat-treated to form a stable contact with reduced Schottky Barrier Height.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If metal silicide contacts are used to achieve low resistivity and good adhesion, then electrical conduction is improved, but reaction with SiO2 and interface stress increase
Solution Approach 1:
An insulator film is introduced as an intermediary layer between the metal silicide contact and the silicon substrate. This intermediate insulator film prevents direct harmful reactions between the metal silicide and SiO2, reduces interface stress, and enables low-resistivity electrical conduction through oxygen vacancy formation that creates conductive pathways.
2Length of moving object
If feature dimensions are reduced to 10 nm and smaller, then device scaling is achieved, but contact performance and processing compatibility deteriorate
Solution Approach 1:
The insulator film undergoes parameter changes through heat treatment that creates oxygen vacancies, transforming it from an insulating state to a partially conductive state. This parameter change enables the contact to maintain low resistivity and good performance even at feature dimensions of 10 nm and smaller, while the insulator framework preserves processing compatibility.
3Ease of manufacture
If traditional metal silicides are used for germanium-containing devices, then contact formation is simplified, but thermal stability and adhesion worsen
Solution Approach 1:
A composite structure is formed combining metal silicide material with an insulator film containing oxygen vacancies. This composite material integrates the low-resistivity electrical conduction of metal silicide with the thermal stability and adhesion properties of the insulator film, achieving both ease of manufacture and improved stability for germanium-containing devices.
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
The approach results in MIS contacts with improved electrical conduction, thermal stability, and reduced interface stress, offering advantages over traditional metal silicides, particularly for small feature sizes and germanium-based devices.
Implementation Method 1
heat-treating the MIS structure to scavenge oxygen from the TiO2 in the insulator film to the metal-containing electrode layer
Data Source
AI summary
A semiconductor device containing a metal-insulator-semiconductor (MIS) contact and method of forming are described. The method includes providing a semiconductor substrate containing a contact region, depositing an insulator film on the contact region, the insulator film including a mixed oxide material containing TiO2 and at least one additional metal oxide. The method further includes depositing a metal-containing electrode layer abutting the insulator film to form a MIS structure, and heat-treating the MIS structure to scavenge oxygen from the TiO2 to the metal-containing electrode layer to form a MIS contact with oxygen vacancies in the TiO2. According to one embodiment the at least one additional metal oxide is selected from HfO2, ZrO2, Al2O3, and combinations thereof, and the metal-containing electrode layer is selected from the group consisting of Ti metal, Al metal, Hf metal, Zr metal, Ta metal, Nb metal, and a combination thereof.