Selective Deposition for BEOL Dielectric Etch Protection
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Low-k materials used in the back-end-of-line (BEOL) integrated circuit fabrication process are prone to damage during dry etch plasma processes, affecting critical dimensions and profile control of interconnects, and require effective methods to mitigate damage, seal pores, and maintain structural integrity.
Innovation Solution
A method involving surface functionalization of dielectric materials using gas phase plasma followed by exposure to silanizing reagents to form and incrementally deposit thin dielectric films, such as SiOx, which acts as a protective barrier against etching and carbon depletion, and seals pores in porous low-k materials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If low-k materials are used in BEOL fabrication, then dielectric constant is reduced for better signal integrity, but material damage occurs during dry etch plasma processes
Solution Approach 1:
A protective film is formed on the low-k material surface before the dry etch plasma process. This preliminary protective layer prevents direct exposure of the porous low-k material to harsh plasma conditions, thereby preventing material damage while allowing the low-k material to maintain its signal integrity benefits.
Solution Approach 2:
The patent introduces a protective film as an intermediary layer between the low-k material and the dry etch plasma. This intermediary layer acts as a buffer that protects the low-k material from direct plasma damage while allowing the etching process to proceed on the protective film itself.
2Reliability
If porous low-k materials are used, then dielectric constant is reduced, but pores need to be sealed to prevent damage
Solution Approach 1:
The patent specifically addresses porous low-k materials by forming a protective film that seals the pores. The protective film deposition process is designed to penetrate and fill the porous structure, creating a sealed protective layer that maintains the underlying pore structure while preventing plasma damage.
3Object-affected harmful factors
If conventional protective methods are used, then material damage is reduced, but critical dimension control and profile precision deteriorate
Solution Approach 1:
The patent employs specific parameter optimizations in the protective film formation process, including controlling film thickness, composition, and deposition conditions. These parameter changes ensure that the protective film is thin enough to maintain critical dimension control while still providing sufficient protection against plasma damage.
4Object-affected harmful factors
If multiple sequential exposures are performed, then film thickness is increased for better protection, but process complexity increases
Solution Approach 1:
The patent uses periodic sequential exposures where the substrate is alternately exposed to silanizing reagent and plasma treatment. This periodic action allows the protective film to be built up incrementally in controlled steps, providing better protection while maintaining manageable process complexity through repetition of a standardized cycle.
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 method effectively reduces low-k material damage, maintains precise via and trench profiles, and enhances the structural integrity of low-k materials by forming a protective dielectric film that suppresses interaction with planarizing materials and prevents carbon depletion, thereby improving the reliability of interconnects.
Implementation Method 1
exposing the substrate to a gas phase plasma to functionalize a surface of the dielectric material
Implementation Method 2
exposing the substrate to a silanizing reagent that reacts with the functionalized surface of the dielectric material to form a dielectric film
Data Source
AI summary
Embodiments of the invention address several issues and problems associated with etching of dielectric materials for BEOL applications. According to one embodiment, the method includes providing a patterned substrate containing a dielectric material, exposing the substrate to a gas phase plasma to functionalize a surface of the dielectric material, exposing the substrate to a silanizing reagent that reacts with the functionalized surface of the dielectric material to form a dielectric film, and sequentially repeating the exposing steps at least once to increase a thickness of the dielectric film. According to one embodiment, the dielectric material may be a porous low-k material, and the dielectric film seals the pores on a surface of the porous low-k material.