Multi-Step Contact Barrier Deposition for Uniform Titanium Nitride
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Solution Overview
Problem
Conventional methods for depositing titanium nitride (TiN) barrier layers in integrated circuit fabrication result in unreliable ICs due to impurities and non-uniform deposition, affecting the sticking coefficient and reliability of the resulting devices.
Innovation Solution
A multi-step process involving ionized metal plasma deposition, metal organic chemical vapor deposition, and thermal chemical vapor deposition is used to form a 'mixed type' contact barrier layer, comprising layers of titanium and titanium nitride, with optional annealing in nitrogen, to enhance the sticking coefficient and uniformity of the TiN layer on silicon substrates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional PVD or CVD processes are used to deposit TiN barrier layers, then the deposition process is simple and fast, but the resulting layers contain impurities and exhibit non-uniform deposition, reducing the sticking coefficient and IC reliability
Solution Approach 1:
The deposition process is divided into multiple sequential steps using different deposition techniques. The patent employs a multi-layer structure where Ti layers are deposited using ionized metal plasma PVD and TiN layers are deposited using CVD, with intermediate cleaning steps. This segmentation allows each layer to be optimized for specific properties, improving overall uniformity and reducing impurities while maintaining process efficiency.
2Reliability
If conventional single-step TiN deposition is used, then the process complexity is low, but the sticking coefficient is non-uniform across the substrate surface
Solution Approach 1:
The patent combines multiple deposition techniques (ionized metal plasma PVD and CVD) into a single integrated deposition system. The system merges the advantages of both methods by using ionized metal plasma for Ti layer deposition and CVD for TiN layer deposition, achieving uniform sticking coefficient across the substrate while maintaining process integration and reducing overall complexity.
Solution Approach 2:
The patent introduces intermediate cleaning steps using oxygen plasma or RF bias between the Ti and TiN layer depositions. These intermediary steps remove contaminants and reactive byproducts from the substrate surface, ensuring uniform adhesion and sticking coefficient for subsequent layers, thereby improving reliability without significantly increasing process complexity.
3Reliability
If conventional TiN deposition processes are used, then the deposition speed is high, but reactive byproducts from the deposition process contaminate the substrate and reduce layer quality
Solution Approach 1:
The patent employs periodic cleaning cycles using oxygen plasma or RF bias between deposition steps. This periodic action removes reactive byproducts and impurities that accumulate during high-speed deposition, maintaining layer purity without significantly reducing overall productivity. The alternating deposition-cleaning cycles ensure high-quality layers while preserving efficient production rates.
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 improves the reliability and uniformity of the TiN layer, reducing impurities and reactive byproducts, thereby enhancing the overall performance and reliability of integrated circuit devices.
Implementation Method 1
A layer of titanium (Ti) is deposited onto the substrate using an ionized metal plasma (IMP) physical vapor deposition process
Implementation Method 2
A first layer of titanium nitride (TiN) is deposited onto the layer of Ti using a metal organic chemical vapor deposition (MOCVD) process
Implementation Method 3
A second layer of TiN is deposited onto the first layer of TiN using a thermal chemical vapor deposition process
Implementation Method 4
The newly completed barrier layer is annealed in the presence of nitrogen at a temperature of between about 500° C. to about 750° C.
Data Source
AI summary
A method for depositing a barrier layer onto a substrate is disclosed. A layer of titanium (Ti) is deposited onto the substrate using an ionized metal plasma (IMP) physical vapor deposition process. The IMP process includes: generating gaseous ions, accelerating the gaseous ions towards a titanium target, sputtering the titanium atoms from the titanium target with the gaseous ions, ionizing the titanium atoms using a plasma, and depositing the ionized titanium atoms onto the substrate to form the layer of Ti. A first layer of titanium nitride (TiN) is deposited onto the layer of Ti using a metal organic chemical vapor deposition (MOCVD) process. A second layer of TiN is deposited onto the first layer of TiN using a thermal chemical vapor deposition process. The newly completed barrier layer is annealed in the presence of nitrogen at a temperature of between about 500° C. to about 750° C.