VERTICAL CONDUCTING CONNECTION TO A POLY-Si TRENCH IN Si
Original Publication Date: 1989-May-01
Included in the Prior Art Database: 2005-Jan-28
Current processing techniques in the microelectronics industry are capable of embedding a poly-Si trench within single crystal Si. The steps for doing this are shown in Fig. 1. Fig. 1A depicts an etched trench 10 in Si 12 having a SiO2/Si3N4/SiO2 lining 14. Trench 10 is filled by deposition of heavily doped poly-Si 16 (Fig. 1B), followed by chemical-mechanical polishing to remove the excess Si on the surface, resulting in an planarized surface 18, as shown in Fig. 1C. The surface is then oxidized so that the poly-Si is covered by thick SiO2, layer 20. Very little oxide will grow on the surrounding Si surface because the Si3N4 film will act as a growth barrier. By chemical etching, the nitride on the Si surface will be removed.