Determination of the Thickness of Chemically Removed Thin Layers on GaAs VPE Structures

✍ Scribed by K. Somogyi; M. Németh-Sallay; Á. Nemcsics

• Publisher: John Wiley and Sons
• Year: 1991
• Tongue: English
• Weight: 379 KB
• Volume: 26
• Category: Article
• ISSN: 0232-1300
• DOI: 10.1002/crat.2170260824

✦ Synopsis

Thinning of epitaxial GaAs layers was studied during the surface etching, with a special attention to submicron epitaxial structures, like MESFET or varactor-type structures. Each chemical treatment influences the crystal surface dunng the device preparation processes, though the possible thinning of the active layer is small. Therefore a method allowing determination of thicknesses as small as at about 20 nm of the layer removed by chemical etching from GaAs VPE structures was applied. Using special multilayered structures and a continuous electrochemical carrier concentration depth profiling, the influence of the layer thickness inhomogeneity and of some measurement errors can be minimized. Some frequently used etchants and the influence of different -so callednon-etching processes were compared in different combinations. It was shown that besides the direct etching a change of the surface conditions occurs, which influences the etch rate in the succeeding etching procedure. k13ySe~O XBneHUe YTOHSeHUX 3IIUTaKCUUIbHbIX IIJIeHOK GaAs npu XUMUYeCKOfi 0 6 p a 6 0 ~~e . Oco6oe BHUMaHRe 06paueao H a CY6MUKPOHHbIe 3IIWTaKCUanbHbIe CTPYKTYPbI Tuna BapUKaIIOB U nOJIeBblX TpaH3HCTOpOB. KaXAbIfi mar XUMUYeCKOfi 0 6 p a 6 o ~~u BJIUReT H a IIOBepXHOCTb B IIpOIleCCe n0nyYeHAF npu6OpoB, XOTX B03MOXHOe YTOHYeHHe aKTUBHOr0 CJIOX OYeHb ManeHbKOe. nO3TOMY TaKOfi MeTOA 6b1n IIpUMeHeH, KOTOPbIfi IIO3BOnWJI OIIpeAeneHUe A3MeHeHUX TOJII4UHbI B pa3Mepe OKOJIO 20-11 HaHOMeTpOB. npUMeHRX CIIeIlUanbHbIe MHOrOCnOGHbIe CTPYKTYpbI U 3IIeKTPOXUMASeCKYH) np0-@UJIOMeTpUIO paCIlpeAeneHLiX CBO6OAHbIX HOCllTenefi TOKa, BnUXHNe HeOAHOpOAHOCTU 3nkiTaKCUaJIb-HOfi nneHKIl U IIOrpeIIIHOCTM UHCTPYMeHTaUUU MOXeT 6bITb CylUeCTBeHHO CHHXCeHO. HeKOTOpbIe 06bIYHbIe TpaBATeJIH 6bmu npkiMeHeHb1 B