Self-Aligned Via Formation via Orthogonal Metal Oxidation
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Solution Overview
Problem
The semiconductor industry faces challenges in filling high aspect ratio trenches with high-quality dielectric materials and selectively etching metal-containing materials, particularly in chip designs with smaller critical dimensions, where existing methods struggle to achieve conformal gapfill and selective etching of metal-containing films.
Innovation Solution
A method involving the oxidation of metal films to expand them orthogonally, followed by the deposition of a dielectric layer and subsequent etching using metal halides to create openings, allowing for gapfill metal deposition and electrical contact, while maintaining the fidelity of feature shapes and aspect ratios.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If existing gapfill and hardmask methods are used, then device isolation can be achieved, but filling high aspect ratio trenches with high-quality dielectric materials becomes increasingly difficult as device dimensions shrink
Solution Approach 1:
The patent applies preliminary action by forming a sacrificial metal layer and mask structure before the actual gapfill process. The metal layer is deposited and patterned in advance to define the regions where dielectric material will be deposited, enabling conformal filling of high aspect ratio trenches without requiring complex in-situ patterning during the gapfill step
Solution Approach 2:
The patent uses a metal layer as an intermediary material between the substrate and the final dielectric gapfill. This metal layer serves as a temporary structure that defines the gap regions, allows for precise pattern transfer, and can be selectively removed afterward to reveal the filled trenches, thereby simplifying the overall process compared to direct dielectric deposition and patterning
2Reliability
If conventional etching processes are used, then material removal can be achieved, but selective etching of metal-containing materials relative to dielectrics is limited
Solution Approach 1:
The patent employs parameter changes by utilizing plasma chemistry parameters to achieve selective etching. By adjusting plasma power, pressure, gas composition, and temperature, the process selectively removes metal-containing materials while preserving dielectric layers, enabling high selectivity for various metal oxides and nitrides without requiring separate etch processes for each material type
3Productivity
If device dimensions continue to shrink, then functionality per unit area increases, but the gap/space between devices decreases making physical isolation increasingly difficult
Solution Approach 1:
The patent applies segmentation by dividing the substrate into distinct regions separated by sacrificial metal structures. These metal segments define isolated regions for device formation, ensuring physical isolation even at reduced pitch. The segmented approach allows independent processing of each device region while maintaining precise spacing and alignment
Solution Approach 2:
The patent transitions from two-dimensional planar isolation to three-dimensional vertical isolation by forming high aspect ratio sacrificial metal structures that extend vertically through multiple device layers. This dimensional change enables effective device isolation in the vertical dimension, allowing tighter lateral spacing while maintaining adequate isolation through the thickness of the device stack
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 conformal gapfilling without seam formation and selective etching of metal oxides relative to dielectrics, facilitating the creation of self-aligned vias and electrical contacts in high aspect ratio structures, enhancing the precision and functionality of semiconductor devices.
Implementation Method 1
The first material is oxidized to expand the first material straight up from the first surface through the opening in the mask to extend above a top surface of the mask forming an expanded first material
Implementation Method 2
The first material is oxidized comprising exposing the first material to an oxidizing agent comprising one or more of O2, O3, N2O, H2O, H2O2, CO, CO2
Implementation Method 3
The first material extending from the substrate surface is etched through the third material by exposing the first material to a metal halide
Data Source
AI summary
Processing methods comprising selectively orthogonally growing a first material through a mask to provide an expanded first material are described. The mask can be removed leaving the expanded first material extending orthogonally from the surface of the first material. Further processing can create a self-aligned via.