Copper Adhesion via Titanium Intermediary Layer
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Solution Overview
Problem
The formation of copper oxides during processing in semiconductor fabrication inhibits the adhesion of subsequent dielectric layers, affecting copper adhesion and electromigration resistance, which are critical for device yield and lifetime, especially with the shift to copper interconnects and low k dielectric materials.
Innovation Solution
A method involving the deposition of an adhesion layer using organometallic precursors like tin or zinc, followed by plasma treatments such as H2, NH3, or H2/He plasma, to improve the adhesion between copper metal layers and dielectric barrier layers, allowing for the use of oxygen-containing barrier films like silicon oxide without increasing conductor resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If oxygen-containing barrier films (e.g., silicon oxide) are deposited directly on copper layers, then the dielectric constant is reduced, but copper oxide forms and adhesion deteriorates
Solution Approach 1:
A titanium adhesion layer is deposited between the copper interconnect layer and the oxygen-containing dielectric barrier layer. This intermediary layer prevents direct contact between copper and oxygen, eliminating copper oxide formation while maintaining strong adhesion. The titanium layer serves as a protective mediator that allows the use of low-k dielectric materials without compromising interface integrity.
Solution Approach 2:
The titanium adhesion layer is deposited on the copper layer before the dielectric barrier layer is applied. This preliminary action of creating an oxide-resistant interface ensures that when the oxygen-containing dielectric material is subsequently deposited, no copper oxidation occurs, preserving both adhesion and allowing low dielectric constant materials to be used.
2Reliability
If conventional deposition methods are used on copper, then copper oxide forms, but adhesion of subsequent layers is inhibited
Solution Approach 1:
The titanium adhesion layer acts as an intermediary between copper and the dielectric barrier layer, preventing copper oxidation that would otherwise inhibit adhesion. This mediator layer ensures both electromigration resistance is maintained and adhesion quality is preserved, as the titanium prevents harmful chemical reactions at the interface.
3Reliability
If copper interconnects are used with low k dielectric materials, then conductor resistance is reduced, but copper oxidation during processing increases
Solution Approach 1:
The titanium adhesion layer serves as a protective intermediary that prevents copper oxidation during subsequent processing steps involving low-k dielectric materials. This allows the copper interconnect structure to maintain its low resistance properties while the titanium barrier prevents copper from reacting with oxygen during dielectric deposition processes.
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 method enhances copper adhesion and electromigration resistance, enabling the use of reduced dielectric constant barrier films while maintaining low conductor resistance, thus improving semiconductor device performance and reliability.
Implementation Method 1
introducing a precursor to the processing chamber to selectively deposit an adhesion layer at least on the at least one patterned conductive metal layer
Implementation Method 2
exposing the substrate having the adhesion layer to a post-treatment selected from the group consisting of H2 plasma, NH3 plasma, H2/He plasma, H2/N2 plasma and mixtures thereof
Implementation Method 3
depositing a dielectric barrier layer on the substrate having the adhesion layer
Data Source
AI summary
The present invention relates to the improved adhesion between a patterned conductive metal layer, usually a copper layer, and a patterned barrier dielectric layer. The structure with the improved adhesion comprises an adhesion layer between a patterned barrier dielectric layer and a patterned conductive metal layer. The adhesion layer improves adhesion between the metal layer and the barrier layer without increasing the copper bulk electrical resistance. The method of making the structure with the improved adhesion comprises steps of thermal expositing the patterned conductive metal layer to an organometallic precursor to deposit an adhesion layer at least on the top of the patterned conductive metal layer.