Electron Beam Observation Stabilizing Charge for Contact Holes
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Solution Overview
Problem
Conventional pre-charging methods for observing high aspect ratio contact holes in semiconductor devices fail to maintain stable electrostatic charge, leading to repeated negative charging and reduced pre-charging effects when using higher magnification electron beams, making repeated observations impossible.
Innovation Solution
A method involving step-by-step adjustment of the electron beam irradiation range and accelerating voltage to form a moderate electric gradient around the observation area, preventing secondary electrons from being pushed back and maintaining a stable electrostatic potential, allowing for efficient detection and repeated observation of contact holes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a beam of electrons is irradiated on a narrower range with higher magnification to observe contact holes, then observation precision is improved, but the pre-charging effect decreases and secondary electrons are pushed back to the workpiece causing negative charging
Solution Approach 1:
The electron beam irradiation process is divided into multiple stages: a first irradiation on a wide range to establish positive electrostatic charge, followed by a second irradiation on a narrower observation range. This segmentation allows the wide-area irradiation to create a reservoir of positive charge that can sustain the high-magnification observation without depleting too quickly, thereby maintaining both observation precision and pre-charging effect.
Solution Approach 2:
The method performs preliminary electrostatic charging by irradiating a wide range of the workpiece surface before conducting the actual high-magnification observation. This preliminary action builds up a sufficient positive electrostatic charge reservoir that prevents secondary electrons from being pushed back during subsequent narrow-range irradiation, thus maintaining stable observation conditions.
2Reliability
If a beam of electrons is irradiated on a wider range to enhance pre-charging effect, then pre-charging effect is improved, but observation precision decreases due to lower magnification
Solution Approach 1:
The electron beam irradiation process is divided into multiple stages: a first irradiation on a wide range to establish positive electrostatic charge, followed by a second irradiation on a narrower observation range. This segmentation allows the wide-area irradiation to create a reservoir of positive charge that can sustain the high-magnification observation without depleting too quickly, thereby maintaining both observation precision and pre-charging effect.
Solution Approach 2:
The method performs preliminary electrostatic charging by irradiating a wide range of the workpiece surface before conducting the actual high-magnification observation. This preliminary action builds up a sufficient positive electrostatic charge reservoir that prevents secondary electrons from being pushed back during subsequent narrow-range irradiation, thus maintaining stable observation conditions.
3Measurement precision
If observation and measurement are carried out with higher magnification on a narrower range, then measurement precision is improved, but the potential of the spot to be observed decreases making repeated observation difficult
Solution Approach 1:
The method performs preliminary electrostatic charging by irradiating a wide range of the workpiece surface before conducting the actual high-magnification observation. This preliminary action builds up a sufficient positive electrostatic charge reservoir that prevents secondary electrons from being pushed back during subsequent narrow-range irradiation, thus maintaining stable observation conditions.
Solution Approach 2:
The method changes the irradiation range parameter from wide to narrow between the first and second electron beam irradiations. By controlling the range parameter, the system maintains positive electrostatic charge during high-magnification observation, preventing the potential decrease that would otherwise occur and enabling repeated stable observations.
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 stabilizes the electrostatic charge potential around the observation area, enabling stable and repeated observation of contact holes by preventing negative charging and maintaining the pre-charging effect, thus facilitating accurate dimensional measurement.
Implementation Method 1
a beam of electrons is irradiated on a first region in the surface of a workpiece
Implementation Method 2
the surface of the workpiece is electrostatically charged positively by pre-charging
Implementation Method 3
secondary electrons are apt to be pushed back to the workpiece
Data Source
AI summary
For the purpose of repeatedly observing the bottom of a contact hole with a high aspect ratio, the potential of an electrostatic charge in each of a pattern to be observed and a vicinity of a range to be observed is stabilized by pre-charging a range on which to irradiate a beam of electrons while changing the range on a step-by-step basis.