Selective Etching of Aluminium Oxide Using Fluoride Inhibitors
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Solution Overview
Problem
The semiconductor industry faces challenges in selectively removing aluminium oxide from microelectronic substrates without affecting underlying metal conductor layers like tungsten and cobalt, which is crucial for achieving precise critical dimensions in vias and trenches during the fabrication of microelectronic devices.
Innovation Solution
An aqueous etching composition comprising a source of fluoride and a metal corrosion inhibitor, with a pH range of 3 to 8, is used to selectively remove aluminium oxide or nitride materials from microelectronic substrates, while minimizing etching of metals and low-k dielectric materials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional wet etching processes are used to remove aluminium oxide, then the etching process can proceed, but the underlying metal conductor layers (tungsten and cobalt) and low-k dielectric materials are adversely affected
Solution Approach 1:
The patent applies parameter changes by adjusting the pH to a specific range (3-8) and selecting particular fluoride sources and metal corrosion inhibitors to achieve selective etching. This resolves the contradiction by modifying chemical parameters to enable high etch rates for aluminium oxide while minimizing damage to underlying metal layers and low-k dielectric materials.
2Productivity
If high etch rates are achieved for aluminium oxide removal, then productivity increases, but selectivity against metal layers and low-k dielectric deteriorates
Solution Approach 1:
The patent introduces metal corrosion inhibitors as intermediary substances that mediate between the fluoride etchant and the metal conductor layers. These inhibitors protect the metal layers from excessive etching while allowing the etch process to proceed at high rates for aluminium oxide, thus resolving the contradiction between productivity and selectivity.
Solution Approach 2:
The patent modifies chemical parameters including pH control (3-8), fluoride source selection, and inhibitor concentration to achieve optimal etch rates for aluminium oxide while maintaining selectivity. This resolves the contradiction by finding the right parameter balance that enables both high productivity and manufacturing precision.
3Productivity
If the pH is lowered to increase etch rate of aluminium oxide, then productivity improves, but corrosion of metal layers increases
Solution Approach 1:
The patent uses metal corrosion inhibitors as intermediaries that become particularly effective at lower pH values. These inhibitors counteract the increased corrosion tendency at low pH while maintaining high etch rates for aluminium oxide, thus resolving the contradiction between productivity improvement through pH reduction and the harmful corrosion effect on metal layers.
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 achieves high etch rates for aluminium oxide or nitride materials while maintaining low etch rates for metals and low-k dielectric materials, ensuring precise removal without damaging the substrate components.
Implementation Method 1
contacting the material with an aqueous etching composition comprising: an etchant comprising a source of fluoride
Implementation Method 2
a metal corrosion inhibitor; wherein the composition has a pH in the range of from 3 to 8
Data Source
AI summary
A method of selectively removing aluminium oxide or nitride material from a microelectronic substrate, the method comprising contacting the material with an aqueous etching composition comprising: an etchant comprising a source of fluoride; and a metal corrosion inhibitor; wherein the composition has a pH in the range of from 3 to 8. Aqueous etching compositions and uses are also described.