Grown-in defects in nitrogen-doped Czochralski silicon

Abstract

Grown-in defects including oxygen precipitates and voids in nitrogen-doped Czochralski (NCZ) silicon have been investigated. It was found that the formation of grown-in oxygen precipitates in NCZ silicon can be divided into two stages. The large precipitates supposed to be enhanced by N2–V2–Ox complexes are generated around 1150 °C, while the small precipitates supposed to be enhanced by NmOn complexes are formed at 750 °C and below. Moreover, it was revealed that the oxygen precipitation behavior in the mixed-type NCZ silicon, which contains vacancy-type and interstitial-type defects distinguished by an OSF-ring in the oxidized wafer, is in sharp contrast to that in the mixed-type Czochralski (CZ) silicon, when subjected to one-step high temperature annealing (1050 °C/32 h) and two-step annealing (800 °C/4 h+1050 °C/16 h). On the other hand, it was found that, compared with CZ silicon, NCZ silicon has much denser crystal originated particles in smaller sizes, which were verified to have been annihilated at relatively lower temperatures. Based on the experimentally found phenomena, a tentative model that takes into account the formation of nitrogen-related complexes involving oxygen atoms and vacancies, void formation, and oxygen precipitation is presented.

On the mechanism of carrier scattering at oxide precipitates in Czochralski silicon

“…Oxygen precipitation (OP) has been a continual subject matter in the research of Czochralski (CZ) silicon for the past decades [1][2][3][4][5][6][7][8]. It is well recognized that OP is a double-edged sword in terms of its influences on the devices.…”

Rapid thermal processing induced vacancy-oxygen complexes in Czochralski-grown Si1−xGex

“…However, the bulk oxide precipitate density could be reduced because the oxygen concentration in larger-diameter Cz-Si wafers and the thermal budgets of manufacturing integrated circuits are decreased to a certain extent. Under the circumstances, two primary strategies i.e., co-doping of nitrogen or germanium during the Cz-Si crystal growth and the pretreatment of Cz-Si wafers by high temperature rapid thermal processing (RTP), have been presented to enhance oxygen precipitation (OP) and therefore increasing the IG capability for Cz-Si wafers [5][6][7][8][9][10][11][12]. The high temperature RTP induces excessive vacancies which are remained after the recombination of Si-interstitials and vacancies.…”

Monocrystalline silicon used for integrated circuits: still on the way

“…The defect engineering that is based on oxygen precipitation and their induced secondary defect, such as the internal gettering (IG) effect, has been challenged by the decrease in oxygen content of larger diameter silicon wafers and by the reduction of thermal budget for device process. An approach to solve such problems is to adopt the silicon wafers with intended impurity doping, such as nitrogen-doped Czochralski silicon wafers [4] and germanium-doped silicon wafers [5]. Epitaxial silicon, strained silicon and silicon on insulator are the innovative silicon based substrates which allow further improvements of electrical device characteristics [6].…”