HARC Dielectric Etch Using Fluorine-Rich Plasma for Profile Control
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Solution Overview
Problem
Conventional high aspect ratio (HAR) etch methods in semiconductor fabrication face challenges such as low wafer throughput, poor uniformity, and severe distortion and twisting of etched features, often requiring multiple processing steps and resulting in missing contacts.
Innovation Solution
A plasma etch process using a gas mixture of nitrogen-containing gases, dioxygen, noble gases, and fluorocarbons is employed to generate a fluorine-rich and nitrogen-deficient plasma, which selectively and anisotropically etches dielectric layers to form high aspect ratio features with aspect ratios of 50:1 or higher in a single step, reducing distortion and twisting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional HAR etch methods are used, then etching can be performed, but wafer throughput is low and processing time is long
Solution Approach 1:
The etch process is divided into multiple phases with different gas compositions: an initial phase without nitrogen-containing gas to establish basic etching, followed by a second phase with nitrogen-containing gas added to enhance anisotropy and reduce distortion. This segmentation allows optimization of each phase for specific functions, improving overall throughput while maintaining quality.
Solution Approach 2:
The patent employs periodic modulation of gas flows and plasma parameters during the etch process. The nitrogen-containing gas is introduced at specific intervals to control the etch profile and reduce distortion dynamically, enabling faster processing without sacrificing uniformity or increasing distortion.
2Manufacturing precision
If conventional HAR etch methods are used, then etching can be performed, but uniformity and distortion control are poor
Solution Approach 1:
Nitrogen-containing gas acts as an intermediary substance that mediates between the fluorocarbon-based etch chemistry and the substrate. It modifies the plasma composition to reduce distortion and improve uniformity without requiring complex process equipment or multiple separate processing steps.
Solution Approach 2:
The patent systematically varies plasma parameters including gas composition (adding nitrogen-containing gas), power levels, and pressure to optimize the etch profile. These parameter changes enable precise control over anisotropy and distortion while maintaining a relatively simple single-step process configuration.
3Loss of time
If single-step HAR etching is performed, then processing time is reduced, but achieving high aspect ratios with minimal distortion is difficult
Solution Approach 1:
The etch process dynamically adjusts plasma conditions by introducing nitrogen-containing gas during the single-step etch. This dynamic modification of plasma composition enables the process to maintain high aspect ratio quality and minimize distortion while completing the etch in a single step, reducing overall processing time compared to multi-step conventional methods.
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 process achieves high aspect ratio etching with improved uniformity and selectivity to hardmasks, reducing processing complexity and time while maintaining high etch quality, enabling the formation of features with aspect ratios up to 100:1 with minimal distortion and twisting.
Implementation Method 1
A plasma etch process using a gas mixture of nitrogen-containing gases, dioxygen, noble gases, and fluorocarbons is employed to generate a fluorine-rich and nitrogen-deficient plasma, which selectively and anisotropically etches dielectric layers
Implementation Method 2
generating a fluorine-rich and nitrogen-deficient plasma in the plasma processing chamber, fluorine-rich and nitrogen-deficient plasma being made of more number of fluorine species than nitrogen species
Data Source
AI summary
A method of processing a substrate that includes: flowing nitrogen-containing (N-containing) gas, dioxygen (O2), a noble gas, and a fluorocarbon into the plasma processing chamber, the plasma processing chamber configured to hold a substrate including a dielectric layer as etch target and a patterned hardmask over the target layer; while flowing the gases, generating a fluorine-rich and nitrogen-deficient plasma in the plasma processing chamber, fluorine-rich and nitrogen-deficient plasma being made of more number of fluorine species than nitrogen species; and forming a high aspect ratio feature by exposing the substrate to the fluorine-rich and nitrogen-deficient plasma to etch a recess in the dielectric layer.