Evaluation of Interfacial Nitrogen Concentration of RTP Oxynitrides by Reoxidation

Okada, Yoshio; Tobin, Philip J.; Lakhotia, Vikas; Ajuria, Sergio A.; Hegde, Rama I.; Liao, Jimmy C.; Rushbrook, P.; Arias, Louie J.

doi:10.1149/1.2221650

Cited by 40 publications

(7 citation statements)

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“…Reoxidation is an indicator of interfacial nitrogen concentration and its distribution within a wafer and for wafers along a boat. 23 The thickness increase by regrowth in 02 ambient responds clearly to changes in nitrogen incorporation due to different process temperatures, gas flows as well as depletion effects. Therefore reoxidation experiments can be used as in-line monitors for process optimization, thereby avoiding time consuming analytical methods like secondary ion mass spectroscopy (SIMS) and Auger spectroscopy.…”

Section: Introductionmentioning

confidence: 99%

Oxynitridation of Silicon and Postnitridation of Thermal Silicon Oxide in N 2 O in a Vertical Furnace

Lange

Boness

Hendriks

1997

J. Electrochem. Soc.

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Gate and tunnel oxides with nitrided interfaces processed in N2O ambient have been found to improve metal‐oxide semiconductor device performance. The N2O process is determined by strongly temperature‐dependent gas‐phase decomposition chemistry, including endo‐ and exothermic reactions and heat‐transfer effects. This can result in gas depletion and nonstationary equilibrium effects which are affecting the incorporation of nitrogen in silicon oxide. A process optimization of N2O nitrided oxides in a vertical furnace with a batch of 125 wafers is presented for the first time. Direct oxynitridation of silicon and postnitridation of pregrown thermal silicon oxides have been investigated. Reoxidation experiments have been used as a monitor for nitrogen incorporation. In general we found that the variation of the gas flow for a given process temperature and time is the most important variable affecting the process uniformity. Excellent uniformities for thickness (4.5 ± 0.2 nm) and nitrogen incorporation were achieved by using low gas flow values. Furthermore, the nitrogen level [2.0 to 4.5 atom percent (a/o)] appeared to be roughly four times higher than the levels reported for conventional furnaces. The observed results are explained by thermokinetical considerations.

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Section: Introductionmentioning

confidence: 99%

Oxynitridation of Silicon and Postnitridation of Thermal Silicon Oxide in N 2 O in a Vertical Furnace

Lange

Boness

Hendriks

1997

J. Electrochem. Soc.

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“…4 22 The model further asserts that the oxynitridation process reduces C and increases CN. Further, the results of SIMS analysis from Hori et al 9 and Okada et al 24 show that higher oxynitridation temperatures and times lead to higher CN and lower CH.…”

Section: Resultsmentioning

confidence: 98%

Electrical Characterization of Oxynitrided Gate Dielectrics under Constant‐Current Fowler‐Nordheim Stress

Nguyen

Landsberger

Belkouch

et al. 1997

J. Electrochem. Soc.

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Charge defects in metal oxide semiconductor capacitors formed with N,O oxynitrides are analyzed by Fowler-Nordheim tunneling injection stress. These oxides are found to incur fewer interface states and lower flatband voltage shifts, the higher the oxynitridation temperature, between 850 and 1050°C. Analysis of oxide traps during constant-current Fowler-Nordheim stress uncovers complex phenomena in oxide trap creation. Several features of the data indicate an optimum at an oxynitridation temperature of 850 to 950°C, including initial net-positive oxide trap creation, and changes in rates of oxide trap creation. However, the net-negative oxide trapping at high cumulative injected charge simply decreases with higher oxynitridation temperatures. There is evidence that "slow" donor states (or anomalous positive charge) near the Si/SiO 2 interface may be suppressed by this oxide process. ' 3-1 radiation impact-ionization,' 0 charge breakdown,"' Fowler-Nordheim stress -6 8 0, ' 6'18 and deep level transient spectroscopy.'9Several previous studies have shown that the oxynitrides have greater charge-to-breakdown, Qbd, than thermal oxides. Okada et al." 6 show that, the higher the concentration of N,O in the oxynitridation ambient (in the range 0% to 100%), the higher the charge to breakdown, Qbd, and that the Qbd of oxynitrides is two to four times larger (0.5 to 0.9 C/cm 2 ) than the control (thermal) case (0.2 to 0.6 C/cm 2 ). According to Hwang et al., 2 0 if the oxynitridation temperature is high (1000 to 1200°C), the shift of the interface trap density, D,, under a constant current Fowler-Nordheim (CCFN) stress of 10 mA/cm 2 , at high fluence (0.1 to 10 C/cm 2 ) is an order of magnitude lower than the control case. For example, for samples oxynitrided at 1000, 1100, and 1200°C, at a fluence of 1C/cm 2 , Dt at midgap is 4 x 10", 2 x 10", and 6 x 10 cm-2eV-', respectively, while the control has a Dt at midgap of >1.5 x 1012 cm-2 eV-'.Using Auger electron spectroscopy (AES), secondary ion mass spectroscopy (SIMS), and electrical characterization, Hori et al. 9 , have formed a semiempirical formula to explain the dramatic reduction of flatband voltage shift, AV,,, and * Electrochemical Society Active Member.

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“…The nitrogen concentration in those oxynitride layers is of the order of 0.3 at%. This value was estimated by using the method described in [11], i.e. by performing a re-oxidation of the wafer at 900 • C during 10 min in 100% O 2 and subsequently measuring the thickness difference d after and before the re-oxidation.…”

Section: Methodsmentioning

confidence: 99%

Effect of x-ray irradiation on the electrical characteristics of ultra-thin gate oxides

Houssa

Gendt

Bokx

et al. 1999

Semicond. Sci. Technol.

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The effect of x-ray-induced damage on the electrical characteristics of metal-oxide-semiconductor capacitors with ultrathin gate oxide and oxynitride layers is investigated. The tunnelling current of irradiated capacitors is observed to be enhanced in the low gate voltage range, a behaviour quite similar to the increased leakage current observed in electrically stressed devices. On the other hand, the slopes of the time-to-breakdown distributions decrease after x-ray irradiation, indicating that the critical density of traps needed to trigger breakdown in the gate oxide is lower in irradiated capacitors. In addition, the probability of observing soft breakdown of the SiO 2 layer increases after the irradiation. These results suggest that the radiation-induced traps participate in the formation of the percolation path formed in the gate insulator at breakdown or soft breakdown.

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Evaluation of Interfacial Nitrogen Concentration of RTP Oxynitrides by Reoxidation

Abstract: We prepared oxynitrides with different interracial nitrogen concentration ([N~nt]) using RTP. Reoxidation kinetics of these oxynitrides was studied. It was found that reoxidation thickness strongly depends on the [N~nt]. The reoxidation kinetics can be used for the evaluation of [N~n,].

Cited by 40 publications

References 1 publication

Oxynitridation of Silicon and Postnitridation of Thermal Silicon Oxide in N 2 O in a Vertical Furnace

Oxynitridation of Silicon and Postnitridation of Thermal Silicon Oxide in N 2 O in a Vertical Furnace

Electrical Characterization of Oxynitrided Gate Dielectrics under Constant‐Current Fowler‐Nordheim Stress

Effect of x-ray irradiation on the electrical characteristics of ultra-thin gate oxides

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