Premixed Plasma Ion Source for Inline SIMS Ion Species Switching
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Solution Overview
Problem
The challenge in semiconductor manufacturing is the damaging particle contamination caused by SIMS testing, which requires ex-situ testing and discarding the wafer, and the inefficiency of switching gases in SIMS apparatuses, leading to prolonged downtime and reduced productivity.
Innovation Solution
An inline SIMS process using a multiple ion source with a premixed gas mixture of oxygen and inert gases, such as argon, helium, krypton, and xenon, allows for automatic selection and switching of ion species without gas switching downtime, using a magnetic field to select specific ions and maintain a stable plasma.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If SIMS testing is performed using conventional single ion source with gas switching, then ion species can be changed, but the apparatus experiences prolonged downtime and reduced productivity due to gas switching requirements
Solution Approach 1:
The patent combines multiple ion sources (e.g., oxygen ion source and cesium ion source) into a single SIMS apparatus, allowing different ion species to be used simultaneously without gas switching. This merging of multiple ion sources resolves the contradiction by enabling ion species change while eliminating the downtime associated with gas switching operations.
Solution Approach 2:
The SIMS apparatus is designed with multi-functionality to support multiple ion sources and ion species (positive ions from oxygen and negative ions from cesium). This universal design allows the apparatus to perform different SIMS measurements without requiring gas switching, thereby maintaining productivity while providing adaptability for various ion species.
2Measurement precision
If SIMS testing is performed to detect dopant levels and film impurities, then measurement capability is improved, but damaging particle contamination occurs requiring wafer discard
Solution Approach 1:
The patent changes the parameters of the ion source by using cesium instead of oxygen for negative ion detection, and employs low current density operation. These parameter changes enable precise dopant level measurement while minimizing particle contamination, allowing wafers to be retained for downstream processing rather than discarded.
Solution Approach 2:
The patent uses low current density (partial action) in the cesium ion source to achieve sufficient measurement precision for dopant levels while avoiding excessive ion bombardment that would cause damaging particle contamination. This partial action approach maintains measurement capability while reducing harmful effects.
3Adaptability or versatility
If gas switching is performed in SIMS apparatus to change ion species, then ion selection is achieved, but the process becomes time-consuming and inefficient
Solution Approach 1:
The patent segments the ion source system into multiple independent ion sources (oxygen source, cesium source) rather than using a single gas-switching system. This segmentation allows each ion source to operate independently and simultaneously, eliminating the time loss associated with switching gases while maintaining the ability to select different ion species.
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 enhances negative ion detection sensitivity, reduces contamination risks, and increases productivity by enabling seamless ion species switching within the fabrication flow, minimizing downtime and maintenance costs.
Implementation Method 1
injecting a premixed gas mixture of two or more gases into a plasma chamber configured to produce sputtering ions
Implementation Method 2
ejecting sputtering ions from the plasma chamber into a magnetic field, altering an intensity of the magnetic field to select a single species of ions
Implementation Method 3
directing the single species of ions towards a surface of the substrate, and detecting secondary ions sputtered from the surface of the substrate by the single species of ions
Data Source
AI summary
Methods leverage premixed gas mixtures to perform a metrology process on a substrate using an inline secondary ion mass spectrometry (SIMS) process. The premixed gas mixture of two or more gases is injected into a plasma chamber that is configured to produce sputtering ions for the inline SIMS process. The two or more gases produce non-metallic ion species which are compatible with downstream substrate fabrication processes and allow further fabrication to be performed on the substrate after the inline SIMS process has completed. The sputtering ions are ejected from the plasma chamber into a magnetic field. The intensity of the magnetic field is altered to select a single species of ions. The single species of ions are directed towards a surface of the substrate and secondary ions sputtered from the surface of the substrate by the selected species of ions are detected and analyzed.