Diffusion Barrier Layer for DRAM Contact Plug Reliability
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Solution Overview
Problem
Conventional semiconductor devices experience increased vacancy-type defects and junction leakage due to the absorption of silicon-interstitials during high-temperature heat treatments, which shorten data retention time and deteriorate the holding characteristics of DRAMs.
Innovation Solution
A semiconductor device with a diffusion barrier layer that separates polycrystal silicon conductors from single crystal silicon diffusion layers, preventing the diffusion of silicon-interstitials and vacancies, thereby reducing defect formation and junction leakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high-temperature heat treatment is performed to activate phosphorous in contact plugs, then electrical conductivity is improved, but silicon-interstitials are absorbed into the contact plugs causing vacancy-type defects and junction leakage
Solution Approach 1:
A diffusion barrier layer made of silicon nitride or silicon oxynitride is introduced between the polycrystal silicon contact plug and the single crystal silicon diffusion layer. This intermediary layer prevents silicon-interstitials from diffusing into the contact plug during heat treatment, thereby suppressing vacancy-type defect formation while allowing the heat treatment to proceed for electrical activation.
Solution Approach 2:
The harmful silicon-interstitials are extracted from the diffusion path by removing them through the diffusion barrier layer before they can be absorbed by the contact plug. The barrier layer selectively blocks the diffusion of silicon-interstitials while permitting other necessary processes to occur.
2Stability of the object's composition
If phosphorous implantation is performed for field relaxation, then stress in the semiconductor substrate is reduced, but silicon-interstitials are generated that can be absorbed during subsequent heat treatment
Solution Approach 1:
The diffusion barrier layer serves as a protective intermediary that allows phosphorous implantation for field relaxation to proceed while preventing the subsequently generated silicon-interstitials from migrating to and being absorbed by the contact plug during heat treatment.
3Ease of manufacture
If the contact plug is made of polycrystal silicon for ease of formation, then manufacturing complexity is reduced, but silicon-interstitial absorption occurs more readily compared to single crystal silicon
Solution Approach 1:
The diffusion barrier layer of silicon nitride or silicon oxynitride is positioned between the polycrystal silicon contact plug and the single crystal silicon diffusion layer to prevent silicon-interstitial absorption, thereby enabling the use of easily formed polycrystal silicon without suffering from its high affinity for silicon-interstitials.
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 diffusion barrier layer effectively suppresses the formation of vacancy-type defects and reduces p-n junction current leakage, enhancing data retention time and information holding characteristics in semiconductor memory devices like DRAMs.
Implementation Method 1
a diffusion barrier layer which prevents a diffusion of at least one of silicon-interstitial and silicon-vacancy between the single crystal silicon diffusion layer and the polycrystal silicon conductor
Implementation Method 2
Conventional semiconductor devices experience increased vacancy-type defects and junction leakage due to the absorption of silicon-interstitials during high-temperature heat treatments
Data Source
AI summary
A semiconductor device may include, but is not limited to, a single crystal silicon diffusion layer, a polycrystal silicon conductor, and a diffusion barrier layer. The diffusion barrier layer separates the polycrystal silicon conductor from the single crystal silicon diffusion layer. The diffusion barrier layer prevents a diffusion of at least one of silicon-interstitial and silicon-vacancy between the single crystal silicon diffusion layer and the polycrystal silicon conductor.