Tin Oxide Etch Cycling to Protect Silicon-Containing Layers
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Solution Overview
Problem
In semiconductor device manufacturing, the formation of tin oxide spacers often results in a tin oxide footing near protruding features, which can cause damage to the silicon-containing layer during etching.
Innovation Solution
A method involving alternating passivation and etching steps is employed, where the exposed silicon-containing material is passivated towards a tin oxide etch chemistry, followed by etching the exposed tin oxide using chlorine-based or hydrogen-based etch chemistries, and repeating these steps to reduce tin oxide footing without damaging the silicon-containing layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If tin oxide etching is performed to remove footing, then footing is reduced, but silicon-containing layer is damaged
Solution Approach 1:
The silicon-containing layer is passivated with a protective layer before the tin oxide etching process. This preliminary protective action prevents the silicon layer from being damaged during subsequent etching operations, allowing aggressive etching chemistry to be used effectively to remove footing.
Solution Approach 2:
A passivation layer acts as an intermediary between the tin oxide etch chemistry and the silicon-containing layer. This intermediary layer is selectively removed after etching, having served its protective function during the footing removal process.
2Manufacturing precision
If alternating passivation and etching steps are performed, then footing is reduced without damage, but process complexity increases
Solution Approach 1:
The process employs periodic alternation between passivation steps and etching steps. This rhythmic sequence of protective and removal actions enables precise control over footing reduction while systematically protecting the silicon layer throughout the multi-step process.
Solution Approach 2:
The continuous etching process is segmented into discrete alternating cycles of passivation and etching. Each cycle performs a specific function (protection or removal), and the segmentation allows for precise control and optimization of each individual step's parameters.
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 effectively reduces the tin oxide footing near protruding features while preventing damage to the silicon-containing layer, ensuring precise patterning and formation of small-scale features in semiconductor devices.
Implementation Method 1
passivating the exposed silicon-containing material towards a tin oxide etch chemistry
Implementation Method 2
treating the substrate with a plasma-activated oxygen-containing reactant
Implementation Method 3
etching the exposed tin oxide using a chlorine-based etch chemistry and exposing the semiconductor substrate to a plasma-activated chlorine-containing reactant selected from the group consisting of Cl2, BCl3
Implementation Method 4
exposing the semiconductor substrate to a plasma-activated chlorine-containing reactant
Implementation Method 5
etching the tin oxide using a hydrogen-based etch chemistry that results in a formation of a tin hydride
Implementation Method 6
contacting the semiconductor substrate with a plasma-activated hydrogen-containing reactant
Data Source
AI summary
Tin oxide films are used as spacers and hardmasks in semiconductor device manufacturing. In one method, tin oxide layer (e.g., spacer footing) needs to be selectively etched in a presence of an exposed silicon-containing layer, such as SiOC, SiON, SiONC, amorphous silicon, SiC, or SiN. In order to reduce damage to the silicon-containing layer the process involves passivating the silicon-containing layer towards a tin oxide etch chemistry, etching the tin oxide, and repeating passivation and etch in an alternating fashion. For example, passivation and etch can be each performed between 2-50 times. In one implementation, passivation is performed by treating the substrate with an oxygen-containing reactant, activated in a plasma, and the tin oxide etching is performed by a chlorine-based chemistry, such as using a mixture of Cl2 and BCl3.