P-N Junction Diodes Fabricated Based on Donor Formation in Plasma Hydrogenated P-Type Czochralski Silicon

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E9.26.1

P-N Junction Diodes Fabricated Based on Donor Formation in Plasma Hydrogenated P-Type Czochralski Silicon Y. L. Huang 1, E. Simoen 2, R. Job 1, C. Claeys 2, 3, W. Düngen 1, Y. Ma 1, W. R. Fahrner 1, J. Versluys 4, P. Clauws 4 1)

University of Hagen, Department of Electrical Engineering and Information Technology, D-58084 Hagen, Germany

2)

IMEC, B-3001 Leuven, Belgium Department of Electrical Engineering, Katholieke Universiteit Leuven, B-3001 Leuven, Belgium Department of Solid-state Science, Ghent University, B-9000 Gent, Belgium

3) 4)

ABSTRACT A rather large amount of shallow donors is created in p-type Czochralski silicon (Cz Si) wafers after a hydrogen plasma exposure at ∼270 °C (substrate temperature) and a subsequent annealing in the temperature range of 350-450 °C. This two-step process has been used for the fabrication p-n junction diodes at low temperatures. Current-voltage characteristics show that the breakdown voltages of these diodes are higher than 100 V. The diode leakage is found to be improved after slow ramp annealing at temperatures up to 250 °C. Deep level transient spectroscopy measurements reveal that the oxygen related thermal donor is not the dominant doping species as expected before. INTRODUCTION As one of the most important impurities in silicon, hydrogen was intensively studied during the last decades [1, 2]. This is mainly driven by two reasons: i) the presence of hydrogen is difficult to avoid; ii) hydrogen interacts easily with most of the impurities. Recently, a hydrogen dose of ~1011 cm-3 was observed in as received commercial n-type Cz silicon [3]. Hydrogen is able to enhance the formation of oxygen thermal donors [TD] in silicon [4-8]. The strongest enhancement was observed at an annealing temperature of 350 °C with an enhancement factor of 300 compared with a furnace annealing [8]. The hydrogen related support of TD formation is generally attributed to the hydrogen-enhanced diffusion of interstitial oxygen, Oi [9]. It is known that hydrogen is not involved in the core structure of the TDs [10]. On the other hand, beside the TD formation it has been found that annealing in the temperature range of 300-500 °C leads to the formation of shallow thermal donors (STD) [11-17]. Three families of STD have been observed, namely Al-related STD, N-related STD and H-related STD (STD(H)), with different ionization energies [11, 12]. Photo-thermal ionization spectroscopy (PTIS) measurement has shown that the observed effective-mass-like donors with an ionization energy in the range of 34 to 53 meV shifts to lower frequency when hydrogen is replaced by deuterium [13]. The same effect has been detected by Infrared absorption (IR) [11, 14] and electron nuclear double resonance (ENDOR) measurements [15]. Lots of efforts have been made to resolve the core structure of STDH. It was thought that the NL10 centers from electron-paramagnetic-resonance (EPR) spectra and STD(H)s come from the same origin [14, 16]. Similar as TDs, STD(H) defects are stable up to 500 °C [16]. Recently, a family