Formation of device-grade epitaxial silicon films at extremely low temperatures by low-energy bias sputtering

Abstract

Study on further reducing the epitaxial silicon temperature down to 250°C in lowenergy bias sputtering Summary Abstract: The role of lowenergy ion bombardment during the growth of epitaxial TiN(100) films by reactive magnetron sputtering: Defect formation and annihilation Device-grade epitaxial single silicon layers have been formed at extremely low temperatures of about 300 "C by low-energy bias sputtering in conjunction with in situ substrate surface cleaning and an ultraclean processing environment. Dopant impurities in the target material are fully incorporated into the sputter-deposited silicon film and these impurities are 100% electrically activated without any additional heat cycles. An epitaxial silicon film having a resistivity as low as 0.0014 n cm has been obtained using a heavily arsenic-doped silicon block as a target material. A p-n junction diode formed by directly depositing a phosphorus-doped n-type epilayer on a p-type substrate indicates a reverse current level as low as 1.88 X 10-9 A/cm 2 at a reverse bi.as voltage of 5 V, thus verifying that the in situ substrate surface cleaning by low-energy Ar ion bombardment is very effective and damage free. The electrical characteristics of a grown film have shown a good correlation to the crystal structure of the film, which is primarily determined by the energy of ions concurrently bombarding the growing film surface. 4756 J.

Phase tailoring of Ta thin films by highly ionized pulsed magnetron sputtering

“…Catania et al [5] succeeded in growing bcc-Ta after initial removal of the oxide layer on the Si substrate by etching. Furthermore, Ino et al [9] demonstrated that in situ substrate cleaning by low-energy ion bombardment (a few tens of electron volts) enabled growth of bcc-Ta also on Si wafers [10], and that there exists a window in the process conditions (ion energy and ion flux) where the bcc phase can be synthesized. The position of the process window was shown to depend on the mass of the bombarding species.…”

Ion beam epitaxy of silicon films in an ultrahigh vacuum using a sputtering-type metal ion source

“…9 Thus, the research and development of thin film production equipment are proceeding toward UHV technology with a background pressure ͑P b ͒ below 10 Ϫ7 Pa. The processing of silicon is a typical case in which an UHV environment is strongly required, especially for sophisticated film processes such as UHV-CVD 1 and MBE.…”

“…4 Sputtering systems are a kind of UHV film production equipment. 9 The gaseous contaminants observed in sputtered films usually originate from residual gases, an argon source gas, and gases released through plasma irradiation. 9 A clean silicon surface will oxidize at oxygen or water vapor pressures above 10 Ϫ7 Pa, even at room temperature.…”

“…9 The gaseous contaminants observed in sputtered films usually originate from residual gases, an argon source gas, and gases released through plasma irradiation. 9 A clean silicon surface will oxidize at oxygen or water vapor pressures above 10 Ϫ7 Pa, even at room temperature. 15 Consequently the background pressure ͑P b ͒ must be suppressed below 10 Ϫ7 Pa and the partial pressure ͑P im ͒ of impurity gases introduced into the chamber needs to be suppressed below P b ͑i.e., P im ӶP b Ӷ10 Ϫ7 Pa͒.…”

A simple model for low energy ion-solid interactions

“…4 Recently, significant attention has been drawn to the use of ion irradiation during the growth of thin films to improve morphology as well as the crystallinity of the growing layers. [5][6][7][8][9] The study of ion-solid interactions becomes crucial to minimize the damage induced in the film as well as the substrate, while enhancing the growth parameters. Brice et al 10 have employed a partitioning of surface and bulk displacements to characterize the ion-surface interactions.…”