Self-Assembled Monolayer Capping for Clean Cu Interconnect Surfaces
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Solution Overview
Problem
In semiconductor processing, metals like copper easily diffuse into dielectric materials under thermal and electric stress, causing dielectric failure, and existing capping layers are difficult to deposit selectively on copper surfaces, affecting the reliability of Cu metal interconnects.
Innovation Solution
A substrate processing method that selectively forms a sacrificial capping layer using self-assembled monolayers on metal surfaces to prevent metal diffusion and oxidation, which can be later removed to restore the metal surface for further processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a metal capping layer (Ta/TaN or CoWP) is deposited on Cu metal to prevent diffusion, then metal diffusion is prevented, but the process of selectively depositing and subsequently removing the metal capping layer is problematic and affects reliability
Solution Approach 1:
The patent employs a sacrificial organic capping layer that is intentionally designed to be temporary and easily removable. This organic layer serves its protective function during storage and transport, then is completely removed before processing, leaving no residue. The sacrificial nature of this temporary layer resolves the contradiction by providing protection when needed while eliminating the complexity of selective deposition and removal of permanent metal capping layers.
Solution Approach 2:
The patent changes the material parameter from inorganic metal capping layers to organic sacrificial capping layers. This parameter change fundamentally alters the deposition and removal characteristics, enabling simple formation through spin-coating or dip-coating and complete removal through thermal decomposition or chemical etching, thereby resolving the manufacturing process problems associated with metal capping layers.
2Reliability
If a dielectric capping layer is used to prevent metal diffusion, then diffusion protection is provided, but it is difficult to deposit selectively on Cu metal surfaces
Solution Approach 1:
The organic sacrificial capping layer is applied as a universal protective coating that can be deposited on any metal surface including Cu, without requiring complex selective deposition processes. The layer is then completely removed before subsequent processing, eliminating the need for difficult selective deposition while still providing the necessary diffusion protection during storage and transport.
Solution Approach 2:
The organic sacrificial capping layer acts as an intermediary protective barrier that simplifies the manufacturing process. Instead of requiring complex selective deposition of dielectric layers on metal surfaces, the organic layer can be applied universally and then completely removed, serving as a temporary mediator that protects the metal surface without creating subsequent processing difficulties.
3Manufacturing precision
If excess Cu metal is removed by CMP process to planarize the surface, then surface planarization is achieved, but the process time increases and productivity is reduced
Solution Approach 1:
The sacrificial capping layer is formed on the Cu metal surface before any subsequent processing steps. This preliminary protective action prevents the need for extensive CMP processing later, as the capping layer can be selectively removed to reveal the Cu surface at the desired level, thereby reducing overall processing time and improving productivity while maintaining planarization precision.
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 effectively prevents metal diffusion and oxidation, eliminating the need for time constraints in processing and improving productivity by allowing for clean metal surfaces during semiconductor manufacturing.
Implementation Method 1
selectively forming a sacrificial capping layer containing a self-assembled monolayer on the metal surface
Implementation Method 2
The sacrificial capping layer may be formed by exposing the substrate to a reactant gas containing a chemical compound capable of form a self-aligned monolayer
Data Source
AI summary
A substrate processing method includes providing a substrate containing a metal surface and a dielectric material surface, selectively forming a sacrificial capping layer containing a self-assembled monolayer on the metal surface, removing the sacrificial capping layer to restore the metal surface, and processing the restored metal surface and the dielectric material surface. The sacrificial capping layer may be used to prevent metal diffusion into the dielectric material and to prevent oxidation and contamination of the metal surface while waiting for further processing of the substrate.