Multi-Stepped Barrier Layer for Copper Wiring Contact Resistance
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Solution Overview
Problem
In semiconductor devices, the contact resistance between conductive structures and interconnections is unstable due to rapid temperature variations during deposition processes, particularly when copper wirings are involved, leading to void formation and increased resistance.
Innovation Solution
A multi-stepped process is used to form a barrier layer with varying compositions of deoxidizing agents and metal materials, initiated at a lower temperature to minimize thermal budget and prevent damage to conductive structures, resulting in a multi-layered structure that reduces contact resistance and electron migration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a deposition process is performed at high temperature to form the barrier layer, then the barrier layer can be formed with good quality and step coverage, but the contact resistance increases and voids form in the copper wiring due to thermal damage
Solution Approach 1:
The deposition process is divided into multiple temperature stages: an initial low-temperature deposition stage (room temperature to 200°C) to form a first barrier layer without thermal damage, followed by a second deposition stage at higher temperature to form additional barrier layer material. This segmentation allows the barrier layer to be formed with good quality while preventing copper wiring damage and void formation.
Solution Approach 2:
A preliminary low-temperature deposition is performed before the main high-temperature deposition process. This preliminary action forms an initial barrier layer that protects the copper wiring from subsequent thermal damage during the main deposition process, preventing void formation and contact resistance increase.
2Strength
If tungsten source gases are used in the deposition process, then the barrier layer can be formed with good adherence to the insulation interlayer, but fluorine ions diffuse into the insulation interlayer causing damage
Solution Approach 1:
A nitrogen-containing barrier layer material is used as an intermediary between the copper wiring and the fluorine-containing tungsten source gases. This nitrogen-containing layer acts as a diffusion barrier that prevents fluorine ions from reaching and damaging the insulation interlayer, while still allowing good adherence and electrical contact to be maintained.
3Productivity
If rapid temperature variation occurs during the deposition process, then the deposition can be completed quickly improving productivity, but the contact resistance becomes unstable due to electron migration in copper wirings
Solution Approach 1:
The deposition process is segmented into temperature-controlled stages with controlled heating rates. The temperature is increased gradually rather than rapidly, preventing thermal shock and electron migration in the copper wiring, while still maintaining reasonable deposition speed through optimized process parameters at each stage.
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 significantly decreases contact resistance and minimizes void formation on copper wirings, ensuring stable electron migration and accurate control of contact resistance between copper wirings and metal plugs.
Implementation Method 1
Various deposition processes based on chemical reactions of source materials have been utilized for forming the WN layer that is conformal with the profile of the contact hole or the via hole and has high quality of step coverage.
Implementation Method 2
Metals are generally formed into the wiring structure for a semiconductor device by a deposition process and the deposition process through chemical reactions at a high temperature.
Data Source
AI summary
A semiconductor device can include an insulation layer on that is on a substrate on which a plurality of lower conductive structures are formed, where the insulation layer has an opening. A barrier layer is on a sidewall and a bottom of the opening of the insulation layer, where the barrier layer includes a first barrier layer in which a constituent of a first deoxidizing material is richer than a metal material in the first barrier layer and a second barrier layer in which a metal material in the second barrier layer is richer than a constituent of a second deoxidizing material. An interconnection is in the opening of which the sidewall and the bottom are covered with the barrier layer, the interconnection is electrically connected to the lower conductive structure.