Alternating Tin Oxide Etch and Passivation for Silicon Layer Protection
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Solution Overview
Problem
In semiconductor manufacturing, existing methods face challenges in reducing tin oxide footing near protruding features without damaging the underlying silicon-containing layers during the etching process, particularly in achieving precise patterning and selective etching with high etch selectivity.
Innovation Solution
A method involving alternating passivation and etching steps using chlorine-based and hydrogen-based etch chemistries, specifically employing plasma-activated reactants like Cl2, BCl3, H2, and HBr to selectively etch tin oxide while protecting the silicon-containing layers, allowing for the reduction of tin oxide footing without damaging the silicon-containing layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional etching methods are used to remove tin oxide footing, then the tin oxide footing is reduced, but the silicon-containing layer is damaged
Solution Approach 1:
The patent employs alternating etch and passivation cycles with varying process parameters. The etch step uses chlorine-based chemistry at controlled power and pressure to remove tin oxide, while the passivation step uses oxygen plasma to protect silicon-containing layers. By adjusting the duration, power, and gas flow rates of alternating cycles, the process achieves selective removal of tin oxide footing while preventing silicon layer damage.
Solution Approach 2:
The patent implements a periodic alternating process where etching and passivation steps are repeated in cycles. The etch step removes tin oxide footing, followed by a passivation step that protects the silicon-containing layer. This periodic alternation continues for multiple cycles, allowing progressive removal of tin oxide while continuously protecting the underlying silicon layer from damage.
2Manufacturing precision
If high etch selectivity is achieved for tin oxide, then precise patterning is enabled, but the process complexity increases
Solution Approach 1:
The patent segments the etching process into multiple alternating cycles of etching and passivation steps. Each cycle consists of a discrete etch step using chlorine-based chemistry followed by a passivation step using oxygen plasma. This segmentation allows precise control over the etching process, achieving high selectivity for tin oxide while managing process complexity through standardized repeating units.
Solution Approach 2:
The patent introduces oxygen plasma as an intermediary passivation layer during the etching process. This intermediary layer temporarily protects the silicon-containing layers during chlorine-based etching of tin oxide, then is removed in subsequent steps. The intermediary approach enables high etch selectivity while preventing damage to underlying 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
This approach effectively reduces tin oxide footing while maintaining the integrity of the silicon-containing layers, achieving high etch selectivity and precise patterning, which is essential for advanced semiconductor processing applications.
Implementation Method 1
exposing the semiconductor substrate to a plasma-activated chlorine-containing reactant selected from the group consisting of Cl2, BCl3, and combinations thereof
Implementation Method 2
etching the exposed tin oxide using a chlorine-based etch chemistry
Implementation Method 3
treating the substrate with a plasma-activated oxygen-containing reactant
Implementation Method 4
passivation of the silicon-containing layer is performed by treating the substrate with an oxygen-containing reactant
Implementation Method 5
contacting the semiconductor substrate with a plasma-activated hydrogen-containing reactant selected from the group consisting of H2, HBr, NH3, H2O, a hydrocarbon, and combinations thereof
Implementation Method 6
etching the tin oxide using a hydrogen-based etch chemistry that results in a formation of a tin hydride
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.