Oxidation of si Why spend a whole lecture on oxidation of Si? Ge has high ue, Wh, Ge stable but no oxide GaAs has high ue and direct band Why sio? Sio, is stable down to 10 9 Torr. T>900C Sio can be etched with hf which leaves si unaffected Sio, is a diffusion barrier for B. p. as SiO, is good insulator, p>106 Q2cm, E. 8 eV Sio, has high dielectric breakdown field, 500 V/um SiO2 growth on Si= clean Si/ Sio, interface Oxide because DSi through Sio,<< DOxy through Sio2 Sept.19,2003 3.155J/6.152J
Oxidation of Si Why spend a whole lecture on oxidation of Si? Ge has high me, mh , Ge stable… … but no oxide GaAs has high m and direct band… … no oxide e Why SiO2? SiO2 is stable down to 10-9 Torr , T > 900°C SiO2 can be etched with HF which leaves Si unaffected SiO2 is a diffusion barrier for B, P, As SiO2 is good insulator, r > 1016 Wcm, Eg = 8 eV! O2 SiO2 has high dielectric breakdown field, 500 V/mm SiO2 growth on Si fi clean Si / SiO2 interface because DSi through SiO2 << DOxy through SiO2 SiO2 Si dtOxide Sept. 19, 2003 3.155J/6.152J 1
So Sio2 growth occurs at inside surface Oxide Si+O2→S02 Si+ 2H20=Si02+ 2H wth, more porous, lower quality Unsaturated Bond 0262nm 0.162nm Oxyge con Oxygen Silicon Sept19,2003 3.155J6.152J
2 So SiO2 growth occurs at inside surface Si + O2 Æ SiO2 or Si + 2H2O = SiO2 + 2H2 (faster growth, more porous, lower quality) O2 SiO2 Si dtOxide Sept. 19, 2003 3.155J/6.152J
ata Extra free volume in dangling bonds of amor phous SiO, Implications different for field vs patterned oxide 3.155J/6.152
O2 SiO2 Si dtOxide in dangling bonds of => Extra free volume amorphous SiO2 Implications different for field vs. patterned oxide. Sept. 19, 2003 3.155J/6.152J 3
Cleaning station for removing organic contaminants and native oxide(by HF-dip) from si wafers Oxidation furnaces for controlled growth oxide layer on Si 1050 C and steam for field oxide Sept.19,2003 3.155J/6.152J
Cleaning station for removing organic contaminants and native oxide (by HF-dip) from Si wafers. Oxidation furnaces for controlled growth of oxide layer on Si: 1050 C and steam for field oxide. Sept. 19, 2003 3.155J/6.152J 4
Probably safe to say that entire course of semiconductor industry would be different without Sio 2 Device fabrication, especially mOs more difficult Depositing Sio2 or ALO3 is not clean Sept.19,2003 3.155J/6.152J
Probably safe to say that entire course of semiconductor industry would be different without SiO2. Device fabrication, especially MOS, more difficult. Depositing SiO2 or Al2O3 is not clean. Sept. 19, 2003 3.155J/6.152J 5