Si (211) substrate thinning technology for HgCdTe focal plane arrays on Si substrates

A wet chemical etching method for (211)Si substrates was demonstrated in this paper. The morphologies and cleanness of (211) Si surface etched in different mixture ratio HF-HNO 3 -HAC solutions have been studied by using optical microscope and the surface profile measuring system (SPMS). The analysis of the surface images indicated that the Si etched by the HF-HNO 3 -HAC (2:15:5) has the smoother surface, and the wet chemical etching can effectively eliminate the damage introduced by the chemo-mechanical polishing. An auto wet chemical etching agitator which can move in the vertical orientation was used. The wet chemical etching rate of (211) Si was obtained in the room temperature and the transmitted spectra of (211) Si with different thickness were measured by Fourier Transform Infrared Spectroscopy (FTIR) and compared. It is confirmed that the Si with different thickness make no difference to the spectral response in mid-wave. By using this novel technology, the Si substrate of HgCdTe/Si detector was removed completely with the HF-HNO 3 - HAC (2:15:5) solution. It is obvious that the wet chemical etching method can remove the (211) Si substrates with no damage and detector can work better.