Remote Plasma Etching Radical Density Control
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Solution Overview
Problem
Semiconductor etching processes face challenges in achieving consistent and repeatable results due to variations in radical density and chamber conditions, leading to uniformity and control issues across multiple etch processes.
Innovation Solution
The method involves measuring radical density in a remote plasma region during etching and chamber cleaning, using hydrogen-containing and fluorine-containing precursors to control the etch process, and halting the flow of precursors based on specific radical density thresholds to ensure precise etching and consistent chamber conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If wet HF etch is used to preferentially remove silicon oxide, then etch selectivity is improved, but penetration ability into constrained trenches deteriorates and material deformation occurs
Solution Approach 1:
The patent changes the physical state and chemical composition parameters of the etching medium from liquid HF to plasma-based etchants (such as CF4, SF6, or NF3 mixed with H2), enabling the process to penetrate constrained trenches while maintaining selectivity through controlled plasma chemistry and ion bombardment energy
Solution Approach 2:
The patent replaces the wet chemical etching mechanism with a plasma-based physical-chemical etching process, where reactive species in the plasma phase enable trench penetration and ion directionality prevents material deformation while maintaining etch selectivity
2Object-affected harmful factors
If dry plasma etching is used to penetrate constrained trenches, then trench penetration ability is improved, but substrate damage from electric arcs occurs
Solution Approach 1:
The patent modifies plasma process parameters including gas composition (adding H2 to CF4/SF6/NF3), pressure, and power density to suppress arc formation while maintaining plasma reactivity for effective trench penetration without substrate damage
Solution Approach 2:
The patent uses composite plasma chemistry combining fluorocarbon gases (CF4, SF6, NF3) with hydrogen (H2), where the composite plasma provides both the fluorine radicals needed for silicon oxide etching and the hydrogen needed to suppress arc discharge and reduce substrate damage
3Productivity
If multiple etch processes are performed in the same chamber, then productivity is improved, but uniformity and repeatability of etch results deteriorate due to chamber condition variations
Solution Approach 1:
The patent implements real-time monitoring of chamber conditions (pressure, temperature, gas flow rates, and plasma parameters) with automatic feedback control systems that adjust process parameters between wafers to maintain consistent etch results despite chamber condition variations
Solution Approach 2:
The patent performs preliminary chamber conditioning and calibration before processing sequences, and uses predictive models to pre-adjust process parameters for subsequent wafers based on measured chamber drift, ensuring uniformity across multiple etch processes
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 allows for precise control over etch processes, achieving repeatable results with a margin of error within 5% of initial etch processes, improving uniformity and process control by maintaining consistent chamber environments.
Implementation Method 1
The measuring may be performed with an optical emission spectrometer positioned within a dielectric component at least partially defining the remote plasma region of the semiconductor processing chamber
Implementation Method 2
forming a plasma of the fluorine-containing precursor in the remote plasma region... etching a pre-determined amount of a silicon-containing material from a substrate
Implementation Method 3
flowing a hydrogen-containing precursor into a semiconductor processing chamber... flowing a fluorine-containing precursor into a remote plasma region
Data Source
AI summary
Exemplary etching methods may include flowing a hydrogen-containing precursor into a semiconductor processing chamber. The methods may include flowing a fluorine-containing precursor into a remote plasma region of the semiconductor processing chamber. The methods may include forming a plasma of the fluorine-containing precursor in the remote plasma region. The methods may include etching a pre-determined amount of a silicon-containing material from a substrate in a processing region of the semiconductor processing chamber. The methods may include measuring a radical density within the remote plasma region during the etching. The methods may also include halting the flow of the hydrogen-containing precursor into the semiconductor processing chamber when the radical density measured over time correlates to a produced amount of etchant to remove the pre-determined amount of the silicon-containing material.