Carbon-Doped FCVD Oxide Layers for Wet Etch Isolation Control
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Solution Overview
Problem
The challenge in semiconductor device fabrication is the difficulty in forming nanometer-scale trench features in FinFET devices due to tip-to-tip shorting caused by the inadvertent removal of dielectric isolation layers during wet etch processes, which affects device performance.
Innovation Solution
A plasma doping method using a primary dopant gas and a diluent gas, such as carbon-containing gases, is employed to reduce the wet etch rate of flowable chemical vapor deposition (FCVD) oxide layers, where the diluent gas is provided in amounts of 0.01%-5% by volume, and carbon is implanted into the wafer to make the oxide layers less susceptible to etching.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If wet etch process is used to form nanometer-scale trench features, then manufacturing precision is improved, but dielectric isolation layers are inadvertently removed causing tip-to-tip shorting
Solution Approach 1:
The patent applies preliminary action by performing plasma doping with carbon-containing diluent gas on the FCVD oxide layers before the wet etch process. This pre-treatment modifies the oxide layer composition to be more etch-resistant, allowing the subsequent wet etch to selectively remove sacrificial masks without inadvertently etching the isolation layers, thus preventing tip-to-tip shorting while maintaining trench formation precision
Solution Approach 2:
The patent changes the chemical composition parameters of the oxide layer by introducing carbon dopants through plasma doping with diluent gases (0.01%-5% by volume). This parameter change modifies the etch selectivity between the oxide layer and other materials, enabling the wet etch process to distinguish between sacrificial masks and isolation layers, thereby resolving the contradiction between precise trench formation and isolation layer protection
2Manufacturing precision
If diluent gas is added to plasma doping operation, then wet etch rate of oxide layers is reduced, but process complexity increases
Solution Approach 1:
The patent applies universality by using a multi-functional plasma doping process that simultaneously performs dopant introduction and etch rate modification. The diluent gas serves dual purposes: it dilutes the primary dopant gas to control doping concentration and simultaneously introduces carbon-containing species that increase oxide layer etch resistance. This eliminates the need for separate process steps, reducing overall process complexity despite the added gas component
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 significantly reduces the wet etch rate of FCVD oxide layers, preventing tip-to-tip shorting and maintaining electrical isolation between surface features, thereby enhancing the performance and reliability of semiconductor devices.
Implementation Method 1
performing a plasma doping operation on the semiconductor wafer using a primary dopant gas and a diluent gas
Implementation Method 2
an interior component of the system located within the plasma doping chamber is adapted to release carbon molecules into the chamber when subjected to a plasma doping operation
Implementation Method 3
performing a plasma doping operation on the semiconductor wafer using a primary dopant gas, causing carbon from the layer of carbon to be knocked into the semiconductor wafer
Data Source
AI summary
A method for reducing a wet etch rate of flowable chemical vapor deposition (FCVD) oxide layers in a semiconductor wafer, the method including performing a plasma doping operation on the semiconductor wafer using a primary dopant gas and a diluent gas adapted to reduce a wet etch rate of the FCVD oxide layer, wherein the dopant gas and the diluent gas are supplied by a gas source of a plasma doping system, wherein the diluent gas is provided in an amount of 0.01%-5% by volume of the total amount of gas supplied by the gas source 36 during the plasma doping operation, and wherein the primary dopant gas is He and the diluent gas is selected from a group including of CH4, CO, CO2, and CF2.