Case 1: Micro LED aligned bonding study

What did they want?

Plessey operates an in-house single sourced FIB microscope which is capable of making cross-sections. However, it has a relatively low ion beam current, compared to PEMC FIB-SEM, which greatly affects the speed of volume removal. Moreover, the ion beam imaging can potentially cause extra damage and provides a fairly limited imaging resolution. Thus it is of interest to compare the ion milling and electron imaging in PEMC FIB-SEM with Plessey's single beam FIB. 

Agreed analysis plan

  • XeF2 assisted enhance milling to reveal the bonding interface more than 50 ┬Ám in depth in comparison with Plessey's in-house single source FIB in terms of speed
  • SEM live monitoring for the appearance of the bondings and then high-resolution imaging on the polished section


Since the bonding region is about 50 micrometers below the surface (see green lines), a large volume of the material needs to be removed by the ion beam so that the bondings can be clearly observed.

Using Plessey's in-house single source FIB, this was an overnight mission, while in PEMC FIB-SEM it needed four to five hours in the high beam current condition or even better within two hours with gas assisted etching. Furthermore, the electron beam provides better imaging with higher resolution and various contrast. 

All tests carried out demonstrate that the Plessey FIB does not have the capability of the FIB-SEM in PEMC, therefore the accessibility to the state of the art system through PMCP is of great value to Plessey.

Plessey Semiconductors Ltd case 1
Plessey Semiconductors Ltd Case 1 Results