Standard grating samples which are used in Scanning Electron Microscopes (SEMs), would be calibra...

Start Date

2001

End Date

2004

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Development of Nano-Scale Grating Pitch Calibrating Device

 

Standard grating samples which are used in Scanning Electron Microscopes (SEMs), would be calibrated in nano-scale by grating pitch calibrating device. To ensure accuracy and consistence of the pitch, measurement values of the device are traced to length primary standard before application.

 

An auto collimation method of Littrow diffraction was adopted in the device to measuring diffraction angles. After adjustments of the device, the diffracted beam of the grating could directly feed back towards the laser. Then, a twofold Littrow angle value is measured by rotating the angle table. The diffraction beam is back to the laser from +1 diffracted order to -1 diffracted order. The grating pitch is obtained by calculation through Grating diffraction formula. To ensure measuring precision, the incident beam must coincide well with the diffraction beam. The 633nm and 543nm laser sources are traced to laser primary standard, so their wavelength accuracy and stability can be guaranteed.

 

Trough this project:

A set of verification equipment for nanometer grating was established.

Size of grating substrate: 15 mm × 15 mm × 5 mm or 15 mm × 15 mm × 3 mm.

Pitch of the grating: 320 nm / 500 nm.

Relative uncertainty: 1 nm / 3 nm.