Semiconductor Etching Gas Mixture for High-Speed SiO2 and Si Processing
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Solution Overview
Problem
In semiconductor device manufacturing, the etching of silicon oxide (SiO2) and silicon (Si) layers using traditional gas mixtures often results in low etching rates and damage to photoresist masks due to plasma-induced effects, which complicates the formation of complex three-dimensional memory structures.
Innovation Solution
The use of a gas mixture containing cyclic halogenated carbide-based gases, such as C4F4Br4, which dissociates in a plasma to form reactive halogenated carbide-based molecules that enhance etching rates by forming polymers on the substrate and acting as protective films, reducing plasma damage and allowing for high-speed, constant-rate etching of both SiO2 and poly-Si layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional gas mixtures (carbon fluoride compound for SiO2, hydrogen bromide for Si) are used for etching, then high selectivity is obtained, but etching rate is low and photoresist masks are damaged
Solution Approach 1:
The patent changes the chemical composition parameters of the etching gas by introducing a gas mixture containing CF4, C4F8, and HBr in specific ratios. This parameter change enables simultaneous high etching rates for both SiO2 and Si while maintaining selectivity and protecting photoresist masks, resolving the contradiction between traditional high-selectivity/low-rate etching methods
2Reliability
If traditional gas mixtures are used for etching, then selectivity between layers is maintained, but photoresist masks suffer plasma damage
Solution Approach 1:
The patent converts the harmful plasma effects into beneficial protection by using the etching gas mixture to form protective polymer films on the photoresist masks during etching. The CF4 and C4F8 components create fluorocarbon polymers that protect the photoresist from plasma damage while HBr enables controlled Si etching, thus converting potential harm into protective benefit
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 increases etching rates and productivity while reducing manufacturing costs by enabling high-speed, simultaneous etching of multiple layers with minimal selectivity, and protects the photoresist masks from plasma damage, maintaining the integrity of the etched structures.
Implementation Method 1
The use of a gas mixture containing cyclic halogenated carbide-based gases, such as C4F4Br4, which dissociates in a plasma to form reactive halogenated carbide-based molecules
Implementation Method 2
forming polymers on the substrate and acting as protective films, reducing plasma damage
Data Source
AI summary
According to one embodiment, a semiconductor device manufacturing method includes collectively etching layers of a multilayered film including silicon layers and silicon oxide films alternately stacked on a semiconductor substrate. The etching gas of the etching contains at least two types of group-VII elements and one of a group-III element, a group-IV element, a group-V element, and a group-VI element, the energy of ions entering the semiconductor substrate when performing the etching is not less than 100 eV, and an addition ratio of the group-III element, the group-IV element, the group-V element, the group-VI element, and the group-VII element to the group-VII element is 0.5 (inclusive) to 3.0 (inclusive).