Tin Oxide Thin Film Spacers for Pitch-Stable Semiconductor Etching
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Solution Overview
Problem
Conventional spacer materials in semiconductor manufacturing, such as silicon oxide and titanium oxide, lead to pitch walking and particle contamination issues due to low etch selectivity and contamination of etching chambers, respectively.
Innovation Solution
The use of tin oxide as a spacer material, which offers high etch selectivity and forms a volatile hydride that can be easily removed from process chambers, reducing pitch walking and contamination, along with methods for converting tin-containing particles to tin hydride for chamber cleaning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If silicon oxide is used as spacer material, then etch selectivity is improved, but pitch walking occurs due to inconsistent lateral spacer sidewall consumption
Solution Approach 1:
The patent changes the material parameter from silicon oxide to tin oxide, which has different etch selectivity characteristics. Tin oxide provides adequate etch selectivity while consuming laterally at a consistent rate during etching, thereby resolving the pitch walking issue that occurs with silicon oxide spacers
2Reliability
If titanium oxide is used as spacer material, then etch selectivity is improved, but particle contamination occurs in etching chambers
Solution Approach 1:
The patent changes the material parameter from titanium oxide to tin oxide. Tin oxide provides adequate etch selectivity for spacer formation and does not generate contaminating particles in etching chambers, unlike titanium oxide which generates titanium fluoride particles during fluorocarbon plasma etching
Solution Approach 2:
The patent employs a chamber cleaning process using hydrogen plasma to convert any tin-containing particles into volatile tin hydride that can be purged from the chamber. This disposable cleaning approach maintains chamber purity without requiring frequent manual cleaning, thereby resolving the particle contamination issue
3Reliability
If thicker spacers are used to compensate for low etch selectivity, then etch selectivity is improved, but manufacturing precision deteriorates due to inconsistent lateral consumption
Solution Approach 1:
The patent changes the material parameter to tin oxide, which inherently provides consistent lateral sidewall consumption during etching. This eliminates the need to increase spacer thickness to compensate for poor etch selectivity, as tin oxide achieves both adequate selectivity and consistent lateral consumption at thinner dimensions
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
Tin oxide spacers provide consistent lateral sidewall consumption, reduce edge roughness, and facilitate efficient chamber cleaning, enhancing productivity by minimizing contamination and pitch walking issues.
Implementation Method 1
tin forms a highly volatile hydride, which can be easily removed from the process chambers
Implementation Method 2
converting any tin-containing materials (such as tin fluoride) to tin hydride (e.g., by plasma treatment in a hydrogen-containing process gas)
Data Source
AI summary
Thin tin oxide films are used as spacers in semiconductor device manufacturing. In one implementation, formation of spacers involves deposition of a tin oxide layer on a semiconductor substrate having multiple protruding features. The deposition is performed in a deposition apparatus having a controller with program instructions configured to cause sequential contacting of the semiconductor substrate with a tin-containing precursor and an oxygen-containing precursor such as to coat the semiconductor substrate having the protruding features with a tin oxide layer. Next, tin oxide film is removed from horizontal surfaces, without being completely removed from the sidewalls of the protruding features. Next, the material of protruding features is etched away, leaving tin oxide spacers on the semiconductor substrate.