Silicide Contact Liner Structure for Stable Microelectronic Dimensions
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Solution Overview
Problem
Conventional methods for forming conductive contacts in semiconductor devices face challenges such as unintentional contact expansion or reduction, leading to increased risk of short-circuits and high electrical resistance due to cleaning, drying, and cobalt-removal processes, which affect the integrity and performance of silicide regions.
Innovation Solution
The method involves forming a first metal nitride liner within the contact opening before cleaning and drying to protect adjacent dielectric materials, followed by a second metal nitride liner, ensuring precise control of conductive contact structure dimensions and preventing unintended expansion or reduction, thereby maintaining electrical integrity and reducing resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If cleaning, drying, and cobalt-removal processes are performed to form silicide material with sufficient purity, then electrical communication between conductive contact structure and polysilicon structure is improved, but contact expansion occurs leading to increased risk of short-circuits and current leakage
Solution Approach 1:
A dielectric liner is introduced as an intermediary protective layer between the contact opening walls and the cleaning/drying/etching processes. This liner acts as a barrier that prevents direct interaction between the aggressive processing chemicals and the contact structure, thereby maintaining contact dimension precision while still allowing sufficient material removal to achieve pure silicide formation at the contact bottom.
Solution Approach 2:
The dielectric liner is formed in advance, before the cleaning, drying, and cobalt-removal processes begin. This preliminary protective action ensures that the contact opening dimensions are preserved throughout the subsequent processing steps, preventing contact expansion while allowing the necessary material removal to occur at the contact bottom.
2Manufacturing precision
If protective dielectric structure is included around contact opening to prevent contact expansion, then contact dimension stability is improved, but contact reduction occurs leading to increased contact electrical resistance
Solution Approach 1:
The dielectric liner is applied selectively to specific regions - it lines the contact opening walls to prevent lateral expansion, but is removed or does not extend to the contact bottom where cobalt removal and silicide formation occur. This local differentiation allows the liner to provide dimensional stability where needed while preventing contact reduction and maintaining low electrical resistance where material removal is required.
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 prevents contact expansion and reduction, enhancing electrical communication and performance by maintaining the integrity of the conductive contact structures, reducing the risk of short-circuits and improving overall device performance.
Implementation Method 1
forming a first metal nitride liner in the contact opening before cleaning and drying to protect adjacent dielectric materials
Implementation Method 2
Cleaning and drying are performed to remove impurities or other debris from the surface of the polysilicon
Implementation Method 3
cobalt is deposited on the cleaned and dried exposed polysilicon surface and is subjected to a heat treatment to form, from the cobalt and the polysilicon, the CoSi2 at the surface of the polysilicon
Implementation Method 4
Remaining cobalt (e.g., cobalt not converted into CoSi2) is then removed (e.g., by etching or other 'remnant-removal' act)
Data Source
AI summary
Microelectronic devices—having at least one conductive contact structure adjacent a silicide region—are formed using methods that avoid unintentional contact expansion and contact reduction. A first metal nitride liner is formed in a contact opening, and an exposed surface of a polysilicon structure is thereafter treated (e.g., cleaned and dried) in preparation for formation of a silicide region. During the pretreatments (e.g., cleaning and drying), neighboring dielectric material is protected by the presence of the metal nitride liner, inhibiting expansion of the contact opening. After forming the silicide region, a second metal nitride liner is formed on the silicide region before a conductive material is formed to fill the contact opening and form a conductive contact structure (e.g., a memory cell contact structure, a peripheral contact structure).