Semiconductor Wiring Surface Roughness Control via Titanium Underlayer
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Solution Overview
Problem
The challenge in semiconductor memory device manufacturing is forming smooth wiring layers with reduced surface roughness to prevent misalignment and defects, such as bridging between adjacent wires, due to decreased design rules and non-uniform photosensitive layers.
Innovation Solution
A method involving the deposition of a titanium metal underlayer film and an aluminum conductive layer, with controlled temperature conditions, to achieve a substantially uniform surface profile and reduce surface roughness, thereby minimizing defects in the wiring structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a conventional multi-layered wiring structure is formed with decreased design rules, then integration and storage capacity are improved, but surface roughness increases causing non-uniform photosensitive layers and manufacturing defects
Solution Approach 1:
A metal underlayer film (titanium or titanium nitride) is introduced as an intermediary layer between the conductive layer and the insulation layer. This underlayer film has superior planarization properties that enable the overlying conductive layer to form with reduced surface roughness (Ra ≤ 50 Å), thereby achieving uniform photosensitive layer deposition while maintaining high integration
Solution Approach 2:
The patent modifies the structural parameters of the wiring system by adding a dedicated underlayer film with specific material properties (titanium or titanium nitride) and controlled thickness (50-200 Å). This parameter change fundamentally alters the surface morphology characteristics, enabling smooth conductive layer formation despite decreased design rules
2Ease of manufacture
If the conductive layer is deposited directly on the insulation layer without a metal underlayer, then the process is simpler, but the surface profile is non-uniform causing etching defects and bridging
Solution Approach 1:
The metal underlayer film serves as a mediator that decouples the relationship between the insulation layer and conductive layer. It provides a consistently smooth surface (Ra ≤ 50 Å) that enables reliable etching and patterning, preventing bridging and other defects while maintaining process efficiency through standardized deposition procedures
3Manufacturing precision
If the photosensitive layer thickness varies due to surface irregularities, then light irradiation becomes non-uniform, but this variation causes defected patterns and non-uniform etching
Solution Approach 1:
The metal underlayer film acts as a planarizing intermediary that creates a uniformly smooth surface (Ra ≤ 50 Å) beneath the conductive layer. This ensures uniform photosensitive layer thickness across the entire wiring surface, enabling consistent light irradiation and accurate pattern formation without defects
Solution Approach 2:
The metal underlayer film is deposited in advance before the conductive layer and photosensitive layer formation. This preliminary action of creating a smooth surface foundation ensures that subsequent layers are deposited uniformly, preventing pattern defects before they occur
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 method effectively reduces surface roughness and prevents bridging between adjacent wires, enhancing the reliability and yield of semiconductor memory devices by ensuring uniform etching and patterning of the conductive layers.
Implementation Method 1
depositing a metal underlayer film on a semiconductor substrate having at least one circuit element, depositing a conductive layer on the metal underlayer film
Data Source
AI summary
A method of forming a wiring for a semiconductor memory device includes obtaining a semiconductor substrate, depositing at least one conductive layer on the semiconductor substrate under controlled conditions, such as substrate temperature and atmosphere temperature, to provide a conductive layer exhibiting a reduced surface roughness as compared to a comparable conductive layer deposited under uncontrolled conditions, and patterning the conductive layer to form a wiring.