The Nanoscale AFM-CD standard (CD, critical dimension) contains patterns on the nanometer scale for the linewidth and also the pitch calibration of scanning probe microscopy methods (atomic force microscopy (AFM)).

The Nanoscale AFM-CD-standard offers a series of very smooth and sharp-edged line-space structures in silicon with vertical side-walls. The smallest lines are around 50 nm wide, 250 nm deep and extremely parallel with deviations of below 10 nm.

Each calibration chip has a size of 8×8 mm². In the centre of the calibration chip, where the two-stage finding structure ends, 6 groups of 5 line-space structures with different nominal widths (50, 100, 150, 200, 300 and 800 nm) are arranged.

The space between the lines is about 1 μm. Each group is nominally 10 μm long. The structures are sharp-edged with edge radii of less than 15 nm. The edge roughness is well below 5 nm (3σ).
 

Specifications
Substrate	Material: <110> Si Chip dimension: 8×8 mm² Surface roughness: <1 nm
Finding structures	Grooves in the Si-substrate Depth: 250 nm
Types of grating	1-dim
Size of grating	Normally 10×10 µm²
Linewidths (CD)	Nominal: 50 nm, 100 nm, 150 nm, 200 nm, 300 nm, 800 nm Linewidth variation along the lines (measured within a central part of about 1 µm):<3 nm 1σ
Pitches	1 µm + CD value Uncertainty of mean pitch: 3 nm 1 σ
Structure depth	250 nm
Edge radius	<15 nm
Edge roughness	<5 nm (p-p)
Sidewall angle	89°
Traceability	CD & pitch-calibration made by the PTB Braunschweig on request.

Chip and pattern description

SEM micrographs (Zeiss Supra 35 VP)