Selective Doped Silicon Oxide Etch via Remote Plasma
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Solution Overview
Problem
Current dry etch processes lack selectivity in removing doped silicon oxide from patterned substrates without damaging miniature structures, as they often fail to differentiate between doped and undoped silicon oxide, silicon, and silicon nitride.
Innovation Solution
A gas phase etching method using partial remote plasma excitation, where a fluorine-containing precursor is excited in a remote plasma region and its effluents are combined with a hydrogen-containing precursor, such as water, in the substrate processing region to selectively react with and remove doped silicon oxide, while minimizing the etch rate of other materials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional dry etch processes are used to remove doped silicon oxide, then material removal is achieved, but selectivity between doped silicon oxide and other materials (undoped silicon oxide, silicon, silicon nitride) is insufficient
Solution Approach 1:
The patent applies local quality by creating spatially differentiated plasma conditions: a remote plasma region with high electron density and energy for generating reactive fluorine species, and a substrate processing region with controlled lower energy conditions. This spatial differentiation allows selective chemical reactions at the substrate surface while minimizing physical damage to miniature structures, achieving both high etch selectivity and gentle material removal
Solution Approach 2:
The patent utilizes parameter changes by varying plasma conditions (electron density, temperature, reactive species concentration) between the remote plasma generation region and the substrate processing region. By controlling parameters such as gas flow rates, pressure, and plasma power, the process achieves optimal selectivity for doped silicon oxide removal while protecting other materials from excessive etching or damage
2Productivity
If plasma effluents are used to etch doped silicon oxide, then etch rate is improved, but physical disturbance to miniature structures increases
Solution Approach 1:
The patent extracts the plasma generation function to a remote region separate from the substrate processing area. The remote plasma source generates reactive species that are then transported to the substrate region without the accompanying high-energy ions and electrons that cause physical damage. This separation allows high etch rates through chemical reactions while minimizing physical disturbance to miniature structures
Solution Approach 2:
The patent uses an intermediary transport mechanism to carry reactive fluorine species from the remote plasma region to the substrate processing region. This intermediary approach allows the beneficial chemical etching action to reach the substrate while filtering out the harmful physical components of plasma, achieving high productivity with minimal damage
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 method achieves high selectivity in removing doped silicon oxide, with etch rates significantly higher for doped silicon oxide compared to undoped silicon oxide, silicon, and silicon nitride, reducing damage to patterned substrates and enabling precise control over etch processes.
Implementation Method 1
remote plasma excitation of ammonia and nitrogen trifluoride enables silicon oxide to be selectively removed
Implementation Method 2
The plasma effluents are combined with the unexcited hydrogen-containing precursor in the substrate processing region where the combination reacts with the doped silicon oxide
Data Source
AI summary
A method of etching doped silicon oxide on patterned heterogeneous structures is described and includes a gas phase etch using partial remote plasma excitation. The remote plasma excites a fluorine-containing precursor and the plasma effluents created are flowed into a substrate processing region. A hydrogen-containing precursor, e.g. water, is concurrently flowed into the substrate processing region without plasma excitation. The plasma effluents are combined with the unexcited hydrogen-containing precursor in the substrate processing region where the combination reacts with the doped silicon oxide. The plasmas effluents react with the patterned heterogeneous structures to selectively remove doped silicon oxide.