PVD sputtering - step coverage

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In summary, the conversation discusses the depositing of a thin titanium film on an epoxy encapsulated IC-chip to protect it from corrosive gases. The titanium target has a diameter of 100mm and is placed directly above the chip, with a working pressure of 1E-4 mbar. The question is raised about the film thickness on the sidewall of the chip, with perfect step coverage at 100nm and bad step coverage at 0nm. The response suggests that the coverage on the sidewalls may be poor unless a planetary drive sample holder is used.
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sabine_
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Hi all,

I would like to deposit a thin titanium film (d=100nm) with pvd sputtering on an epoxy encapsulated
IC-chip to protect the chip against corrosive gases.
Titanium target (diameter: 100mm) is straight above IC-Chip (length and width: 6mm, height:2mm), working pressure ~ 1E-4 mbar.
My question is:
What film thickness can I expect at the sidewall (height dimension) of the chip ?
perfect step coverage: ~100 nm or bad step coverage: ~ 0 nm ?

Thanks
Best regards

Sabbi
 
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  • #2
I guess it depends on the distance from the sputter head to the sample. In general sputtering is quite directional so I’d expect very poor coverage on the sidewalls, unless you’re using a planetary drive sample holder.
 

1. What is PVD sputtering step coverage and why is it important?

PVD (Physical Vapor Deposition) sputtering step coverage refers to the uniformity of coating on a three-dimensional substrate. It is important because it determines the quality and functionality of the coating, especially in complex structures where there are varying surface geometries.

2. How does PVD sputtering achieve good step coverage?

PVD sputtering uses energetic particles, typically ions, to bombard the target material and cause atoms to be ejected onto the substrate surface. These atoms then form a thin film that conforms to the shape of the substrate, resulting in good step coverage.

3. What factors affect PVD sputtering step coverage?

The type of sputtering process, such as DC or RF, can affect step coverage. The material and thickness of the target, as well as the substrate material and surface roughness, can also impact step coverage. Additionally, the sputtering conditions, such as gas pressure and substrate temperature, play a role in achieving good step coverage.

4. How can step coverage be improved in PVD sputtering?

To improve step coverage in PVD sputtering, the sputtering conditions can be optimized, such as adjusting the gas pressure and substrate temperature. Target material composition and thickness can also be modified. Using a multi-step deposition process, where the substrate is rotated during coating, can also improve step coverage in complex structures.

5. Are there any limitations to PVD sputtering step coverage?

While PVD sputtering can achieve good step coverage, it may not be suitable for all substrate geometries. Complex structures with high aspect ratios or sharp corners can be challenging to coat uniformly. In such cases, other coating methods, such as chemical vapor deposition, may be more suitable.

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