HDP-CVD Carbon Gapfill for High Aspect Ratio Trenches
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Solution Overview
Problem
Current methods for filling narrow trenches in microelectronics and 3D NAND memory devices with carbon materials face challenges such as voiding, poor film quality, and instability at high temperatures, particularly in high aspect ratio features, where existing amorphous silicon and carbon-based processes suffer from low deposition rates and integration issues.
Innovation Solution
A high density plasma chemical vapor deposition (HDP-CVD) method using a hydrocarbon reactant with a hydrogen to carbon ratio of 2:1 or less, combined with hydrogen, helium, and argon, is employed to deposit a carbon film in the HDP-CVD chamber, generating a plasma with RF energy to fill features while leaving a void, ensuring high thermal stability and easy removal of the carbon film.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If flowable CVD is used to fill narrow trenches, then the trenches can be filled with carbon material, but the as-deposited film quality is poor and requires additional processing steps
Solution Approach 1:
The patent changes the deposition parameters by using HDP-CVD instead of flowable CVD, controlling plasma power, pressure, and gas composition to directly achieve high-quality carbon films with proper density and stress characteristics in a single step, eliminating the need for subsequent steam anneal and UV-cure processes
Solution Approach 2:
The patent extracts and removes the problematic additional processing steps (steam anneal, UV-cure) from the manufacturing process by achieving the desired film quality directly through optimized HDP-CVD deposition parameters, simplifying the overall process flow
2Stability of the object's composition
If amorphous silicon is used as sacrificial fill, then the material can be removed by wet etch, but it has multiple integration issues and poor high temperature stability
Solution Approach 1:
The patent uses amorphous carbon as a sacrificial material that can be easily removed by plasma etch after serving its temporary purpose, replacing the problematic amorphous silicon while maintaining the sacrificial fill functionality and improving integration compatibility
Solution Approach 2:
The patent changes the material composition from amorphous silicon to amorphous carbon and adjusts deposition parameters to achieve the desired balance between high temperature stability and ease of removal by plasma etch, resolving the integration issues
3Manufacturing precision
If conventional CVD is used for gap fill, then deposition can occur, but voiding occurs in high aspect ratio features
Solution Approach 1:
The patent replaces conventional thermal CVD with plasma-enhanced HDP-CVD, using plasma activation to enable deposition in high aspect ratio features without voiding while maintaining practical deposition rates through controlled plasma chemistry and ion bombardment
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 achieves high thermal stability of the carbon film, with minimal shrinkage after annealing at 800°C, and allows for efficient gap filling in high aspect ratio features, addressing the limitations of existing processes by providing a stable and removable carbon material.
Implementation Method 1
generating a plasma by source RF
Implementation Method 2
high density plasma chemical vapor deposition (HDP-CVD)
Implementation Method 3
RF energy is coupled into the chamber through coils inductively and generating high density plasma
Implementation Method 4
ions being accelerated by the bias RF
Implementation Method 5
the process gas comprising a hydrocarbon reactant having a hydrogen to carbon (H:C) ratio that is less than or equal to 2:1
Data Source
AI summary
Methods for filling a substrate feature with a carbon gap fill, while leaving a void, are described. Methods comprise flowing a process gas into a high density plasma chemical vapor deposition (HDP-CVD) chamber, the chamber housing a substrate having at least one feature, the process gas comprising a hydrocarbon reactant, generating a plasma, and depositing a carbon film.