Technology

Technology insight from SEM principles to process applications

SEM scans a sample surface with an electron beam in vacuum and converts signals generated by electron-sample interaction into images and analytical data. HiKM connects this principle to tool selection, defect review, metrology, and maintenance decisions.

Compared with optical microscopy

SEM uses electrons and electromagnetic lenses instead of light and glass lenses. It observes surface microstructures at high magnification in vacuum rather than in air.

Compared with TEM

TEM mainly uses transmitted electron information, while SEM uses signals generated from the sample surface such as secondary and backscattered electrons.

Value in semiconductor inspection

With deep depth of focus, rich surface information, and signal selectivity, SEM supports CD measurement, defect review, elemental analysis, and process feedback.

SEM Comparison

Optical microscope and SEM comparison

The right tool depends on the inspection objective and required resolution. SEM uses electron-beam observation and is suitable for high-magnification, high-resolution surface analysis.

Light source / beamOptical microscopes use visible light, while SEM uses an electron beam.
ResolutionThe deck compares optical microscopy at 200 nm or above and SEM at 10 nm or below.
MagnificationOptical microscopy is presented at 10x-3,000x, while SEM is presented at 1,000x-1,000,000x.
MediumOptical microscopy operates in air, while SEM observes samples in vacuum.
SEM column concept showing electron beam path, lenses, detector, and sample stage
SEM 컬럼과 전자빔 경로를 표현한 기술 이미지

How an SEM system creates an image

The electron beam generated by the electron gun is reduced into a small probe through condenser and objective lenses. Scan coils move the probe across X-Y positions on the sample surface, and detectors convert the signal intensity at each position into image brightness and contrast.

  • Electron gun: stable electron emission and beam current generation
  • Electron lenses: control of probe size, resolution, and focus conditions
  • Vacuum system: reduces electron scattering and sample contamination
  • Detectors: collect SE, BSE, and X-ray signals for each observation goal

Signal Strategy

SEM signals to select by observation goal

This section organizes electron-solid interaction, SEM overview, optical microscope vs. SEM comparison, and SEM analysis characteristics in a way technical buyers can understand quickly.

SE / Secondary electronsSignals generated near the sample surface, suitable for checking surface morphology and micro-pattern contrast.
BSE / Backscattered electronsHigher-energy emitted electrons, useful for composition contrast, subsurface information, and material contrast.
X-ray / EDSUses X-rays generated by electron-sample interaction to identify elemental information at selected locations.
Signal combinationFor defect review and process analysis, SE, BSE, and EDS are interpreted together to connect morphology, composition, and location information.
01Define the goal

Clarify whether the goal is CD measurement, defect review, elemental analysis, or surface observation.

02Set conditions

Tune acceleration voltage, probe current, working distance, and detector choice for the sample and analysis goal.

03Connect to operation

Connect recipes, repeat inspection, ADR/ADC/EDS, data upload, and maintenance into the operating workflow.

SEM Comparison Detail

Key comparison criteria between optical microscopy and SEM

Selection criteria vary by inspection purpose and required resolution, so light source, resolution, magnification, and operating environment are reviewed together.

SourceOptical microscopes use visible light, while SEM uses an electron beam.
ResolutionOptical microscopy is generally used for 200 nm and above, while SEM can review below 10 nm depending on conditions.
MagnificationOptical microscopy typically covers about 10x-3,000x, while SEM can be used for high-magnification analysis around 1,000x-1,000,000x.
Magnification methodOptical microscopy directly magnifies through light and lenses, while SEM forms images through scan-area control and signal detection.
MediumOptical microscopy can operate in atmosphere, while SEM generally relies on a vacuum environment.