Characterization of hydrophobic bonded silicon wafers

• Direct bonding of silicon-to-silicon has been recognized as an interesting method for creating novel device geometries and structures and it has so far been used for the preparation of power devices and sensors. The influence of the bonded interface on electrical performance is then of great interest. In this contribution the interface region of hydrophobic bonded n-type silicon wafers have been studied and a comparison is made between samples before and after an exposure to low doses of 9.5 MeV protons to see the effect of the interface on point defect kinetics, The samples were studied using current-voltage (IV), capacitance-voltage (CV). deep level transient spectroscopy (DLTS). secondary ion mass spectrometry (SIMS) and scanning electron microscopy (SEM). During reverse bias there is a dramatic increase in leakage current when the depletion region reaches the bonded interface region. Due to the high leakage currents DLTS measurements could not be performed directly at the interface. However. in contrast to previous studies. no deep levels are discovered in the interface region of non-irradiated samples and, furthermore, no influence of the bonded interface on the concentration and depth distribution of irradiation induced defects could be detected. This suggests that the irradiation induced defects are unaffected by the bonded interlace, At the interface a boron peak is detected by SIMS.

Nyckelord

deep level

bonded interface

grain boundary

proton-irradiated silicon

interface

boron

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