Semiconductor Multilayer Stack for Ru Reaction Control
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Solution Overview
Problem
Semiconductor memory devices face challenges in achieving a thin conductive multilayer structure with low resistance and high conductivity while preventing undesirable reactions between ruthenium (Ru) and the conductive base layer, which are typically resolved by using a sufficient thickness of the conductive barrier layer, resulting in an undesirable thicker structure.
Innovation Solution
A multi-layer structure is implemented with conductive layers including polycrystalline silicon, metal silicide, and titanium nitride as diffusion barriers, and ruthenium as an electrode, where these layers are formed using sequential deposition and thermal processing to control reactions and maintain low resistance, allowing for a thinner structure without adverse interactions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If the conductive barrier layer is made thin to reduce multilayer structure thickness, then the multilayer structure becomes thinner and more compact, but undesirable reactions occur between ruthenium and the conductive base layer
Solution Approach 1:
A separate conductive barrier layer is introduced as an intermediary between the ruthenium layer and the conductive base layer. This barrier layer physically separates the two materials, preventing direct reaction between ruthenium and the conductive base layer while still allowing for a thin overall structure when optimized thickness is used.
Solution Approach 2:
The patent uses a composite multilayer structure combining ruthenium, conductive barrier layer, and conductive base layer materials. Each layer is selected for its specific properties: ruthenium for low resistance and high conductivity, conductive barrier layer for reaction prevention, and conductive base layer for electrical conduction. The composite structure achieves both thinness and reliability through proper material combination.
2Reliability
If the conductive barrier layer is made thick to prevent reactions between ruthenium and the conductive base layer, then reaction prevention is improved, but the multilayer structure becomes thicker
Solution Approach 1:
The patent optimizes the thickness parameter of the conductive barrier layer to a specific range that provides sufficient reaction prevention while minimizing overall structure thickness. By carefully controlling the barrier layer thickness within an optimized range, the patent achieves both reliability in preventing reactions and compactness of the final structure.
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 enables the formation of a thinner, high-conductivity multilayer structure by controlling reactions between ruthenium and the conductive base layer, achieving reduced resistance and compactness while maintaining reliability and performance.
Implementation Method 1
conductive barrier layer that is on a conductive base layer... To prevent such reactions between the ruthenium (Ru) and the conductive material, the conductive barrier layer should have sufficient thickness
Implementation Method 2
these layers are formed using sequential deposition and thermal processing to control reactions and maintain low resistance
Data Source
AI summary
Apparatuses and methods for fabricating multilayer structures are described. An example method includes: forming a conductive base layer including silicon; forming a first conductive layer including first conductive material above the conductive base layer; forming a conductive barrier layer above the conductive layer; performing thermal loading to form a second conductive layer including silicide of the first conductive material between the conductive base layer and the conductive barrier layer; and forming a third conductive layer above the conductive barrier layer.