Regensburg 2010 – wissenschaftliches Programm
Bereiche | Tage | Auswahl | Suche | Downloads | Hilfe
HL: Fachverband Halbleiterphysik
HL 10: Devices II
HL 10.3: Vortrag
Montag, 22. März 2010, 14:30–14:45, H13
Ammonium hydroxide (NH4OH) as etch-stop chemical for highly boron-doped silicon δ-layers — •Oliver Hammer, Florian Palitschka, Helmut Lochner, Tina Kubot, Dorota Kulaga-Egger, Daniel Beckmeier, Carolin Axt, Josef Biba, Ronny Schindler, Marc Dressler, Torsten Sulima, and Walter Hansch — Universität der Bundeswehr München, Institut für Physik, Werner-Heisenberg-Weg 39, 85577 Neubiberg
The downscaling process in current microelectronics results in smaller devices and thinner layers. A proper etch-stop for such thin layers, e.g. boron-doped δ-layer (<10nm) in a vertical device, becomes more and more challenging. Therefore an etchant with an exceedingly high selectivity to boron-doped silicon is needed. Only two wet-chemical silicon etchants, TMAH and the not common NH4OH, are capable for CMOS technology and are not too highly toxic. The major advantage of NH4OH in comparison to TMAH is its high selectivity of 1:8000 for intrinsic silicon with respect to boron-doped silicon. The disadvantages are formation of hillocks and more pronounced surface roughness compared to TMAH. We optimize etching parameters by variation of the etch temperature, the concentration of NH4OH in water and the ratio of 2-propanol in the solution to achieve an etch-stop at a δ-layer without breaking it. Recent experiments show that a solution of TMAH and 2-propanol decreases the surface roughness and the formation of hillocks. Due to this we also perform tests with 2-propanol in a NH4OH solution. Finally we etch a bulk unipolar device (BUD) to determine the electrical characteristics of the exposed δ-layer.