Dielectric Etch Pre-cleaning for Oxide Removal
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Solution Overview
Problem
Cyclic dry etching of dielectric materials is hindered by surface oxide layers, which reduce etch thickness per cycle and degrade selectivity between dielectric materials and oxides, leading to poor etch profile control and increased surface roughness.
Innovation Solution
A pre-cleaning process using thermal reactions and/or plasma treatments to remove surface oxides before the dry etch process, ensuring no break in vacuum between pre-cleaning and etching, and employing cyclic dry etching with fluorine or chlorine containing plasmas to enhance etch selectivity and control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If cyclic dry etching is performed directly on dielectric materials with surface oxide, then the process is simple, but etch thickness per cycle is reduced and selectivity is degraded
Solution Approach 1:
A pre-cleaning step is performed before the cyclic dry etching process to remove surface oxides from the dielectric material. This preliminary action ensures that the etching starts from a clean surface, improving etch thickness control and selectivity without requiring complex in-situ oxide removal mechanisms during the etch cycle itself.
Solution Approach 2:
The etching process is divided into separate stages: a pre-cleaning stage to remove surface oxides, followed by the cyclic dry etching stage. This segmentation allows each stage to be optimized independently - the pre-cleaning removes harmful oxides while the cyclic etching provides precise thickness control, avoiding the need to combine multiple functions in a single complex step.
2Reliability
If surface oxide is present during etching, then no additional processing is needed, but selectivity between dielectric materials and oxides is degraded
Solution Approach 1:
The harmful surface oxide layer is extracted and removed from the dielectric material surface through a dedicated pre-cleaning process. This extraction eliminates the source of selectivity problems, allowing the cyclic dry etching to proceed with high selectivity between the dielectric material and any remaining oxide structures in the device.
Solution Approach 2:
The pre-cleaning process applies a counter-action to remove surface oxides before the main etching process. By eliminating the oxide layer in advance, the subsequent etching process experiences no interference from oxide-related selectivity issues, ensuring reliable and consistent etching results.
3Manufacturing precision
If surface oxide is not removed, then the process is straightforward, but etch profile control is poor and surface roughness increases
Solution Approach 1:
Surface oxides are removed in advance through a pre-cleaning process that includes thermal treatment and/or plasma exposure. This preliminary action creates a clean, uniform surface that enables precise etch profile control during the subsequent cyclic dry etching, avoiding the roughness and profile deviations that would result from etching over oxide layers.
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 pre-cleaning process improves etch profile control, selectivity between dielectric materials and oxides, and reduces surface and sidewall roughness, resulting in consistent etch thickness and superior etch uniformity.
Implementation Method 1
The removal of the oxide can be executed through thermal reaction and/or plasma process before the dry etch process
Implementation Method 2
The removal of the oxide can be executed through thermal reaction and/or plasma process before the dry etch process
Implementation Method 3
pre-cleaning comprises a fluorine or chlorine containing plasma treatment to remove a surface oxide
Implementation Method 4
the dry etching comprises at least one round of H2 plasma treatment and fluorine or chlorine containing radical treatment
Implementation Method 5
the dry etching comprises at least one round of H2 plasma treatment and fluorine or chlorine containing radical treatment
Data Source
AI summary
An etching process is provided that includes a pre-clean process to remove a surface oxide of a dielectric material. The removal of the oxide can be executed through a thermal reaction and/or plasma process before the etch process. In some embodiments, the removal of the oxide increases etch process control and reproducibility and can improve the selectivity versus oxides.