Practical Electron Microscopy and Database

Table 2435. Carbon contamination in IC devices.

Figure 2435 shows an example of C, O, and Si contaminated bond pads. Area S6 had an abnormal film on the native Al oxide, while area S5 presented nonhomogeneous, loose and empty Si_xAl_yC_zO_m materials in the hemispherical defect.  These pad defects existed only at wafer edge because backside grinding was the root cause of the contamination.

However, in many cases, carbon is one of the most difficult contaminants, incorporated from fab-environment, to be detected by analytical TEM such as TEM-EDS and TEM-EELS techniques because of two reasons:
        i) Hydrocarbon (HC) contamination, from the chamber surfaces, vacuum pumps and sample surface migration and then its reaction with the electron beam, often induces background carbon signal. Therefore, it is difficult to distinguish between HC and real carbon contaminants from in-line process.
        ii) The TEM-EDS and TEM-EELS sensitivities are not high enough to detect carbon contents at interfaces or in structures which is able to affect electrical properties of devices.

[1] Paul Yu, Jamie Su, Qiang Gao, Ming Li, Chorng Niou, Study of Aluminum Pad Contamination Sources during Wafer Fabrication, Shipping, Storage and Assembly, International Symposium on High Density packaging and Microsystem Integration, 2007. HDP '07.