Home Ideal cross section analysis tool for structural inspection of sizes greater than 100um

Ideal cross section analysis tool for structural inspection of sizes greater than 100um

Home Ideal cross section analysis tool for structural inspection of sizes greater than 100um

Ideal cross section analysis tool for structural inspection of sizes greater than 100um

by admin

Issued Date: 2016/10/26
Issued By: iST

What else can you do to identify peeling in a product’s structure when cross sectioning by conventional grinding is out of choice?
Is there any time saving, quick, and full structure-viewable tools for large area analysis of PCB, 3D IC, or through-silicon via (TSV) or solder bumps?

Questions like these two have been arriving at iST often lately. In general, Dual-Beam FIB is ideal for cross section analysis of local and small areas which enables fast structural diagram generation with its shooting-while-cutting feature.

This is not the case for large range structural observation (section size greater than 100um or depth greater than 50um) over PCB, TSV, 3D devices, and solder bumps. The limited etching speed and scope of Dual-Beam FIB (DB FIB) is especially so when both fixed-point analysis and concurrent image generation are needed at the same time.

To overcome these drawbacks, we recommend Plasma FIB (PFIB) to replace DB FIB. The former not only features the same shooting-while-cutting capacity possessed by DB FIB but also enables large scope observation to present the whole structure in the target area at etching speeds 20 folds faster than traditional DB FIB. This improves analysis speed effectively.

  • PFIB theory and application overview
    Originating from the same source, PFIB and DB FIB differ from each other in their ion sources and etching speed.
 PFIBDB FIB
Ion sourceXe ion plasma
Ga ions tends to attach to the sample surface
Use of Xe reduces sample contamination by Ga ions
Ga+ ion
Etching speed
(Probe current)
1.3μA
Capable of running over large areas at fast speed
65nA
  • PFIB can be applied in the following fields:
    1. Large range structural observation (100μm or more) including 3D, TSV structures, solder bumps, and packaging products;
    2. Delayer application for advanced processing of 16nm or narrower.

See the cases below for some examples of the use of PFIB.

  • Case1:Solder Bumps

    Instead of local observation of the peeling of solder bumps by conventional methods, the PFIB tool cross sections solder bumps for overall inspection. With a width of cutting point up to 500μm in 2 hours, it far outperforms its older counterpart’s long working hours (10 or more) and limits of local area observing.

    Full-solder-bump-image

    Full solder bump image

    Local area observation available

  • Case 2: TSV structure observation

    Differing from DB FIB‘s time consuming TSV structural observing, the PFIB method not only takes just one hour to finish the sample preparation with the depth and cut point width between 50μm~100μm of a sample, but also enables viewing structures of multiple TSVs concurrently.

    TSV-structure-observation
    TSV-structure-observation

    PFIB features good etching efficiency in a large range for fast and complete presentation of multiple TSV structures.

  • Case 3: IC delayer

    Observing micro structures by advanced process of 16nm or narrower by conventional grinding suffers as the structure is too thin to grind properly. That is, grinding off 2 layers in one treatment or uneven structures after grinding. This is exactly not the case with PFIB as it can grind off structure of large size and layer by layer with plasma etching.

    IC-delayer

We at iST have been striving to share inspection and verification experiences with you. In case you have a sample structure requiring observation, determination and inspection, or just want to know more about this technique, call Miss Tu at 03-579-9909 Ext 6165 or Mr. Li at Ext 6174 or send an email to dbfib_tw@istgroup.com.

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