Manufacturing Method
Silicon nitride support films are manufactured using the latest state-of-the-art semiconductor and MEMS manufacturing
techniques. The thin silicon nitride film is grown on a 200µm thick silicon wafer to the desired membrane thickness
of 50nm or 200nm. The specimen viewing area is created by etching away a window in the silicon wafer substrate underneath the
Si3N4 membrane, leaving a perfectly smooth, resilient and chemically robust
silicon nitride film. The membrane is not supported in the window area, enabling large viewing areas without any disturbing
bars. After finishing the window etching process, the individual frames with the membranes are lifted from the wafer.
Window sizes and shape
Five window sizes are available:
- 0.25 x 0.25mm, most robust membrane
- 0.5 x 0.5mm, sturdy and most cost effective
- 0.75 x 0.75mm, less fragile, relatively large membrane
- 1 x 1 mm, larger area, but more fragile
- 1.5 x 0.5mm, resilient for large viewing area or tomography
Due to the structure of the silicon and the etching process the window in the silicon substrate is etched with a 35°
angle, leaving a much larger opening than the membrane window at the back side of the frame:
| X dimensions (mm) |
Y dimensions (mm) |
Area (mm2) |
Frame thickness
(µm) |
Membrane thickness
(mm) |
X Back side opening
(mm) |
Y Back side opening
(mm) |
| 0.25 |
0.25 |
0.06 |
200 |
50/200 |
0.53 |
0.53 |
| 0.75 |
0.75 |
0.56 |
200 |
50/200 |
1.03 |
1.03 |
| 0.5 |
0.5 |
0.25 |
200 |
50/200 |
0.78 |
0.78 |
| 1 |
1 |
1 |
200 |
50/200 |
1.28 |
1.28 |
| 1.5 |
0.5 |
0.75 |
200 |
50/200 |
1.78 |
0.78 |
Table 1. Window dimensions on standard 200µm frame thickness
Frame dimensions
The frame is manufactured as a 3mm silicon disc with smooth EasyGrip™
edges for easy manipulation by tweezers and will fit perfectly in standard TEM holders. The thickness of 200µm
is more than the typical TEM grid with a thickness of 15-50µm, but should not present a problem in regular TEM
holders. It is recommended that you check the TEM holders you are using. Handling capabilities and smoothness
of the edges are design advantages over other brands of silicon nitride support films. The PELCO® Silicon
Nitride Support Films are manufactured like grids with a 3mm diameter, have no broken edges and are completely
free from debris particles. The mechanical and chemical stability allow for cleaning of the silicon nitride support
films with chemicals (solvents, acids and bases), glow discharge and plasma cleaning. It is recommended that ultrasonic
cleaning not be used, as it can easily shatter the silicon nitride support films.
Effects on tilt
Due to the 35° etching angle the Si3N4 support films on the frames can be tilted to 35° for unobstructed viewing, even if the specimen is close to the edge of the membrane. For higher tilting angles, the specimen needs to be in the centre of the membrane. To allow for the highest possible tilt angle a window size of 1.5 x 0.5mm has been made available, which allows for tilting angles up to 70° with a viewable area of 40%. Maximum tilt angle with a specimen in the centre, maximum tilt angle is 75°.
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