Cyclic Etching Chamber with Remote and Direct Plasma Sources
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Solution Overview
Problem
Existing semiconductor substrate processing technologies face challenges in achieving uniform plasma density, leading to non-uniform processing and equipment damage due to high energetic species and electrons, which complicates advanced etching requirements for small and selective features.
Innovation Solution
A processing chamber with a remote plasma source and a direct plasma source, along with a modular design featuring symmetric flow and exhaust modules, an electrostatic chuck, and a plasma blocking screen, to generate ions and radicals for cyclic etching processes, ensuring uniformity and material selectivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high ion energy plasma is used for anisotropic etching with high aspect ratio structure, then etching capability is improved, but substrate damage increases resulting in device current leakage
Solution Approach 1:
The plasma source is segmented into two distinct sources: a remote plasma source that generates radicals without direct substrate exposure, and a direct plasma source that provides controlled ion bombardment. This segmentation allows the harmful high-energy ions to be separated from the substrate during the radical generation phase, eliminating substrate damage while maintaining etching capability.
Solution Approach 2:
A plasma blocking screen is introduced as an intermediary component between the remote plasma source and the substrate. This screen blocks direct contact between highly energetic plasma species and the substrate, allowing radical transport while preventing ion-induced substrate damage and current leakage.
2Productivity
If plasma is generated in the same location as substrates being processed, then processing efficiency is improved, but equipment degradation increases due to contact with energetic species
Solution Approach 1:
The plasma generation location is segmented from the substrate processing location by using a remote plasma source. The remote plasma source generates plasma in a separate region, allowing efficient plasma generation without direct exposure of chamber components to highly energetic species, thus reducing equipment degradation.
Solution Approach 2:
The harmful highly energetic plasma species are extracted from the direct plasma generation zone and transported to the substrate processing zone. This extraction allows the plasma to be generated in a protected location away from sensitive chamber components, reducing equipment degradation while maintaining processing efficiency.
3Ease of manufacture
If asymmetric chamber design is used, then manufacturing simplicity is improved, but plasma density uniformity deteriorates due to skews in current, gas flow, and thermal distribution
Solution Approach 1:
The chamber design transitions from asymmetric to symmetric configuration. The symmetric chamber body, symmetric flow module, and symmetric exhaust module create balanced gas flow and thermal distribution patterns, eliminating skews in plasma density, current, and temperature that plague asymmetric designs, thereby achieving uniform plasma density across the substrate surface.
4Manufacturing precision
If high ion energy is used for anisotropic etching, then etch profile control is improved, but material selectivity deteriorates making redeposition difficult
Solution Approach 1:
The etching process uses periodic alternation between two plasma modes: a radical-rich mode for selective material removal and an ion-rich mode for profile control. This periodic switching enables both high material selectivity during radical etching and precise anisotropic profile control during ion bombardment, resolving the trade-off between selectivity and profile control.
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 solution provides improved uniformity and selectivity in substrate processing, reducing equipment damage and enabling advanced etching capabilities for small features by generating symmetric plasma conditions and controlled ion and radical exposure.
Implementation Method 1
A source module comprising a plate stack may be coupled to the chamber body and the plate stack may further define the process region and be configured to generate a remote plasma therein
Implementation Method 2
a processing chamber apparatus is provided. The apparatus includes a chamber body defining a process region and configured to generate a direct plasma therein
Implementation Method 3
a substrate support assembly comprising an electrostatic chuck may be disposed within the process region
Data Source
AI summary
A method and apparatus for substrate etching are described herein. A processing chamber described herein includes a source module, a process module, a flow module, and an exhaust module. An RF source may be coupled to the chamber and a remote plasma may be generated in the source module and a direct plasma may be generated in the process module. Cyclic etching processes described may use alternating radical and direct plasmas to etch a substrate.