Selective Oxide Etching via Dual Plasma Mixture for Self-Aligned Patterning
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current semiconductor manufacturing techniques face challenges in achieving precision etching with high selectivity, profile control, and uniformity, particularly in self-aligned multiple patterning, due to the inability to independently control ion energy, ion flux, and radical flux in plasma etch processes.
Innovation Solution
A method involving the formation of two distinct plasma-excited chemical mixtures, one containing an inert gas and He or H2 for surface modification, and another with C, H, and F for selective etching of silicon oxide, allowing for precise control of the etching process and separation of radical and ion flux roles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional plasma etch processes are used, then etching can be performed, but selectivity, profile control, and uniformity cannot be precisely controlled due to inability to independently control ion energy, ion flux, and radical flux
Solution Approach 1:
The etch process is segmented into two distinct sequential steps: (1) surface modification step using plasma containing inert gas and H2/He to modify the first material surface, and (2) selective removal step using plasma containing C, H, and F to selectively etch the modified regions. This segmentation allows independent control of radical flux and ion flux, enabling precise etching with improved selectivity and profile control while managing process complexity through structured separation of functions.
2Manufacturing precision
If self-aligned multiple patterning is used to increase transistor density, then scaling is achieved, but precision material etch becomes more challenging due to densified device structures
Solution Approach 1:
The surface modification step is performed as a preliminary action before the selective etching step. By pre-modifying the first material surface with plasma containing inert gas and H2/He, the material becomes more susceptible to selective etching in the subsequent step. This preliminary action enables precise material removal in high-density self-aligned multiple patterning applications by preparing the surface in advance, thereby achieving both high etch precision and supporting increased transistor density.
3Productivity
If continuous plasma etch processes are used, then etching can be performed continuously, but anisotropy and selectivity are limited
Solution Approach 1:
The etch process uses periodic action by alternating between two distinct plasma steps: (1) surface modification plasma step and (2) selective etching plasma step. This periodic alternation between different plasma chemistries enables precise control over anisotropy and selectivity while maintaining overall process continuity. The cyclic nature of alternating modification and removal steps achieves superior profile control compared to continuous single-plasma 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 enables precise etching with improved anisotropy and selectivity, enhancing the ability to create vertical sidewall profiles and square bottom features, thereby overcoming the limitations of continuous plasma etch processes in semiconductor device fabrication.
Implementation Method 1
forming a first chemical mixture by plasma-excitation of a first process gas containing an inert gas and at least one additional gas selected from the group consisting of He and H2
Implementation Method 2
forming a second chemical mixture by plasma-excitation of a second process gas containing an inert gas and an additional gas containing C, H, and F
Implementation Method 3
exposing the first material on the substrate to the first chemical mixture to modify a first region of the first material
Implementation Method 4
exposing the first material on the substrate to the second plasma-excited process gas to selectively etch the first material, which contains silicon oxide, relative to the second material
Data Source
AI summary
A method of etching is described. The method includes forming a first chemical mixture by plasma-excitation of a first process gas containing an inert gas and at least one additional gas selected from the group consisting of He and H2, and exposing the first material on the substrate to the first chemical mixture to modify a first region of the first material. Thereafter, the method includes forming a second chemical mixture by plasma-excitation of a second process gas containing an inert gas and an additional gas containing C, H, and F, and exposing the first material on the substrate to the second plasma-excited process gas to selectively etch the first material, which contains silicon oxide, relative to the second material and remove the modified first material from the first region of the substrate.