Silicon-Free Carbon Gap-Fill Film Using Pulse Plasma Deposition
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Solution Overview
Problem
Conventional methods for filling high aspect ratio trenches in integrated circuit fabrication face challenges such as void formation, overhangs, and the loading effect, making it difficult to achieve seamless gap-filling without the use of nitrogen, oxygen, or hydrogen plasmas, which are costly and impractical.
Innovation Solution
A silicon-free carbon-containing film is deposited using a pulse plasma-assisted process with a hydrocarbon precursor, where a viscous polymer is formed in a gas phase by striking an inert gas plasma, allowing for bottom-up seamless filling of trenches without the need for nitrogen, oxygen, or hydrogen plasmas, using ALD-like recipes with optimized partial pressure, energy, and temperature conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional plasma-enhanced CVD process is used for gap-filling, then film deposition can be achieved, but void formation and overhangs occur in high aspect ratio trenches
Solution Approach 1:
The patent employs periodic plasma activation in a pulse plasma CVD process, where plasma is applied in discrete pulses rather than continuously. This periodic plasma activation allows reaction products to be deposited in controlled increments, enabling bottom-up filling of high aspect ratio trenches without void formation or overhangs, directly resolving the gap-filling quality versus reliability contradiction
Solution Approach 2:
The patent changes the deposition parameters by using pulse plasma CVD with specific pulse durations, duty cycles, and plasma power levels. These parameter changes enable precise control over film deposition kinetics, allowing the process to achieve both high manufacturing precision in gap-filling and reliable void-free filling in high aspect ratio trenches
2Manufacturing precision
If inhibitor-based gap-fill process is used, then bottom-up fill can be achieved, but suitable combinations of inhibitor and activator are difficult to find
Solution Approach 1:
The patent extracts and eliminates the complex inhibitor-activator chemistry from the gap-fill process. Instead of using chemical inhibitors that require careful selection and combination, the patent uses physical pulse plasma activation to achieve bottom-up filling, dramatically simplifying the manufacturing process while maintaining bottom-up fill capability
Solution Approach 2:
The patent substitutes chemical mechanisms (inhibitor-activator reactions) with a physical mechanism (pulse plasma activation). This replacement simplifies the process by eliminating the need to find suitable chemical combinations, making the manufacturing easier while preserving the desired bottom-up fill behavior
3Manufacturing precision
If highly anisotropic ion-driven deposition is used, then bottom-up fill can be achieved, but mean free path of ions must be significantly increased by reducing pressure
Solution Approach 1:
The patent uses periodic plasma pulses to achieve anisotropic deposition without requiring continuous low pressure. The pulsed nature of the plasma allows ions to be accelerated and directed during each pulse, maintaining anisotropic bottom-up filling while operating at more practical, higher pressures that reduce equipment complexity and operating costs
4Manufacturing precision
If volume expansion treatment is used to close trenches, then gap filling can be achieved, but significant stress is exerted on trench sidewalls causing structural collapse
Solution Approach 1:
The patent uses periodic pulse plasma deposition to build up material incrementally in the trench, avoiding the sudden volume expansion that causes stress. This gradual, controlled deposition achieves gap closing while maintaining trench structural integrity by preventing excessive stress on sidewalls
Solution Approach 2:
The patent performs preliminary deposition of conformal layers before attempting to close the trench. This preliminary action builds a structural foundation that supports the subsequent filling material, preventing sidewall collapse while achieving complete gap closure
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 enables complete gap-filling with minimal voids and stress on trench structures, achieving a bottom-up filling capability that is faster at the trench bottom than on sidewalls and top surfaces, resulting in a high aspect ratio filling without the limitations of traditional methods.
Implementation Method 1
by striking an inert gas plasma
Implementation Method 2
a viscous polymer is formed in a gas phase by striking an inert gas plasma
Implementation Method 3
pulse plasma-assisted deposition
Data Source
AI summary
A Si-free C-containing film having filling capability is deposited by forming a viscous polymer in a gas phase by striking an Ar, He, or N2 plasma in a chamber filled with a volatile hydrocarbon precursor that can be polymerized within certain parameter ranges which define mainly partial pressure of precursor during a plasma strike, and wafer temperature.