Self-Aligned Line-and-Via Structure for Interconnect Alignment
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
As lateral dimensions of metal interconnect structures in semiconductor devices decrease, alignment between metal line structures and metal via structures becomes increasingly difficult, posing a challenge in the manufacturing of semiconductor devices.
Innovation Solution
A self-aligned line-and-via structure is developed, comprising a metal line structure with lengthwise sidewalls, a metallic capping plate overlying the metal line structure, and a metal via structure with sidewalls coincident with the capping plate sidewalls, along with a method involving etch mask processes to form dual damascene metal line and via structures, ensuring precise alignment and formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If lateral dimensions of metal interconnect structures are decreased to increase device density, then device capacity and integration density are improved, but alignment precision between metal line structures and metal via structures deteriorates
Solution Approach 1:
The patent applies preliminary action by forming the metallic capping layer over the first metal layer before patterning the via structures. This capping layer serves as a pre-established reference structure that guides subsequent alignment processes. The self-aligned methodology uses this pre-formed layer to ensure precise positioning of vias relative to lines, solving the alignment precision problem while maintaining high device density.
Solution Approach 2:
The metallic capping layer acts as an intermediary element between the first metal layer (containing line structures) and the second metal layer (containing via structures). This intermediary layer facilitates the transfer of pattern alignment from the line structures to the via structures, enabling precise alignment at smaller dimensions without requiring direct alignment between lines and vias.
2Ease of manufacture
If conventional etch mask processes are used for forming metal line and via structures, then manufacturing process simplicity is maintained, but alignment accuracy between lines and vias deteriorates at small dimensions
Solution Approach 1:
The patent segments the interconnect formation process into distinct sequential steps: first forming the metallic capping layer over the first metal layer, then forming via structures through the capping layer, and finally forming line structures. This segmentation allows each step to be optimized independently while maintaining overall alignment accuracy, resolving the contradiction between process simplicity and alignment precision.
Solution Approach 2:
The patent introduces a vertical dimension solution by stacking layers (first metal layer, metallic capping layer, second metal layer) to achieve horizontal alignment precision. The self-aligned methodology uses vertical layering to control horizontal positioning, effectively transferring the alignment problem from the horizontal plane to the vertical stacking sequence, thereby maintaining alignment accuracy while preserving process simplicity.
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 solution enables precise alignment and formation of metal interconnect structures, improving the manufacturing process by ensuring accurate placement and reducing misalignment issues, particularly in high-density bit lines for three-dimensional memory devices.
Implementation Method 1
transferring a pattern in the via-pattern etch mask through the second metal layer by performing a first anisotropic etch process having a first etch chemistry that etches the second metal selective to the metallic capping material
Implementation Method 2
transferring a pattern in the line-and-space-pattern etch mask at least through the metallic capping layer and the first metal layer by performing a second anisotropic etch process
Data Source
AI summary
An integrated line-and-via structure includes a metal line structure including a first metal and having a pair of lengthwise metal line sidewalls that laterally extend along a first horizontal direction, a metallic capping plate including a metallic capping material and overlying the metal line structure and having a pair of lengthwise metal cap sidewalls that are vertically coincident with the pair of lengthwise metal line sidewalls, and a metal via structure including a second metal and having a pair of lengthwise metal via sidewalls that is vertically coincident with the pair of lengthwise metal cap sidewalls and having a lateral extent along the first horizontal direction that is less than a lateral extent of the metal line structure along the first horizontal direction.