Porous Dielectric Recessed Cap Structure for Low-k Damage Control
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Solution Overview
Problem
Porous dielectric materials used in semiconductor devices are susceptible to damage during processing, leading to degradation of dielectric breakdown strength and increased leakage, which raises the dielectric constant, compromising performance and reliability.
Innovation Solution
A method involving a porous dielectric layer with a recessed portion and a conformal cap layer, where the pore filler is burned out through a gap in the cap layer, maintaining a low dielectric constant while protecting the conductive layer from damage during processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If porous dielectric materials are used to reduce RC delays, then signal transmission speed is improved, but the dielectric is susceptible to damage during processing
Solution Approach 1:
A conformal cap layer is formed over the porous dielectric layer before subsequent processing steps. This cap layer is deposited in advance to provide protective coverage, preventing damage during CMP, plasma exposure, and wet cleans that would otherwise occur to the vulnerable porous dielectric material
Solution Approach 2:
The conformal cap layer acts as an intermediary protective barrier between the porous dielectric layer and harmful processing environments. It mediates the interaction by absorbing mechanical stress during CMP and providing physical protection during plasma and wet processing, allowing the porous dielectric to maintain its low-k properties without damage
2Reliability
If pore sealing is performed to protect porous dielectric, then processing damage is reduced, but dielectric constant increases
Solution Approach 1:
The conformal cap layer provides protection only at the surface and interfaces of the porous dielectric layer, rather than filling the pores. This localized protection approach allows the bulk porous structure to maintain its low dielectric constant while the cap layer prevents processing damage at vulnerable surface regions
Solution Approach 2:
The solution maintains the porous structure of the dielectric layer intact rather than sealing the pores. The conformal cap layer protects the porous material externally, allowing the pores to remain open and maintain low dielectric constant while still providing the necessary protection during processing steps
3Reliability
If conformal cap layer is formed to protect porous dielectric, then processing damage is prevented, but manufacturing complexity increases
Solution Approach 1:
The conformal cap layer serves multiple functions simultaneously: it protects the porous dielectric during CMP, provides barrier protection during plasma processing, prevents wet clean damage, and maintains planarity for subsequent processing. This multi-functionality reduces the need for multiple separate protective layers, thereby limiting the increase in manufacturing complexity
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 effectively protects the porous dielectric material from processing-induced damage, maintaining a low dielectric constant and enhancing the reliability and performance of semiconductor devices.
Implementation Method 1
a conformal cap layer formed on the porous dielectric layer and on the conductive layer in the recessed portion
Implementation Method 2
These materials allow interconnect signals to travel faster through conductors due to a concomitant reduction in resistance-capacitance (RC) delays
Implementation Method 3
performing a heat treatment to burn out a pore filler of the pore-filled dielectric layer through the exposed upper surface of the pore-filled dielectric layer
Data Source
AI summary
A semiconductor device includes a porous dielectric layer including a recessed portion, a conductive layer formed in the recessed portion, and a cap layer formed on the porous dielectric layer and on the conductive layer in the recessed portion, an upper surface of the porous dielectric layer being exposed through a gap in the cap layer.