Copper Interconnect Capping with Noble Metal Liner
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Solution Overview
Problem
Copper interconnects in semiconductor devices experience increased failure due to electromigration as feature sizes decrease, and noble metal liners can interfere with the formation of capping layers, leading to incomplete coverage and enhanced susceptibility to electromigration.
Innovation Solution
A method involving the use of a noble metal liner around copper contacts, followed by electroless deposition of copper and a capping layer, specifically using noble metals like Ru, Pd, Pt, Rh, Au, Ag, and Co or Ni to form a capping layer that reduces electromigration by ensuring complete coverage and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If copper is deposited into etched features in low-k dielectric layers, then conductive interconnects are formed, but electromigration increases failure rate as feature size decreases
Solution Approach 1:
A noble metal liner (Ru, Pd, Pt, Rh, Au, or Ag) is deposited as an intermediary layer between the copper interconnect and the low-k dielectric layer. This liner acts as a barrier that prevents copper atoms from migrating into the dielectric material, thereby reducing electromigration failures while maintaining electrical conductivity.
Solution Approach 2:
The interconnect structure uses a composite material system combining copper (for electrical conductivity) with a noble metal liner (for electromigration resistance). This composite approach leverages the complementary properties of both materials to achieve reliable interconnects at reduced feature sizes.
2Reliability
If a capping layer is deposited over copper contacts, then electromigration is reduced, but noble metal liners interfere with complete coverage
Solution Approach 1:
The noble metal liner is deposited as a preliminary layer before copper filling and capping layer deposition. This pre-deposited liner provides a uniform foundation that ensures subsequent electroless copper deposition and capping layer formation achieve complete and uniform coverage, even in high-aspect-ratio features.
Solution Approach 2:
The noble metal liner serves as an intermediary that facilitates uniform deposition of subsequent layers. Its presence ensures that the electroless copper deposition and capping layer formation proceed uniformly across the contact surfaces, eliminating coverage gaps that would otherwise occur due to the challenging geometry of small features.
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 effectively reduces electromigration failures by ensuring a comprehensive capping layer coverage over copper contacts, even in the presence of noble metal liners, thereby enhancing the reliability of semiconductor interconnects as feature sizes shrink.
Implementation Method 1
Electroless deposition is used to deposit a deposition comprising copper on the noble metal liner and the copper containing contacts
Implementation Method 2
Electroless deposition is used to deposit a capping layer over the deposition comprising copper
Data Source
AI summary
A method of forming a capping layer over copper containing contacts in a dielectric layer with a liner comprising a noble metal liner around the copper containing contacts is provided. An electroless deposition is provided to deposit a deposition comprising copper on the noble metal liner and the copper containing contacts. A capping layer is formed over the deposition comprising copper.