Thin polyoxide films grown by rapid thermal processing

Alvi, N. S.; Lee, S.K.; Kwong, Dim‐Lee

doi:10.1109/edl.1987.26601

Cited by 8 publications

(5 citation statements)

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“…Therefore, RTOi is expected to improve the dielectric strength. Similar results have been reported for RTO1 polyoxides grown on amorphous Si, in situ phosphorus doped or arsenic implantation doped poly-Si (11,12). Electron trapping properties.-- Figure 3 plots the changes of the applied field (AEox) under an electron injection of 100 p2gcm 2 as a function of stress time for both bias polarities.…”

Section: Comparison Of Rapid Thermal Oxidation and Furnacesupporting

confidence: 74%

“…RTO1 of poly-Si results in an increase of ~B,efr for both bias polarities due to the relatively smooth poly-Si/polyoxide interfaces (11,12). After nitridation, the calculated %,eft for both + Vg and -Vg decreases with RTN directly due to the incorporated nitrogen at both poly-Si/polyoxide interfaces.…”

Section: Effects Of Rapid Thermal Reoxidationmentioning

confidence: 92%

“…As a summary, the effective barrier heights ~B,etf obtained based on analysis of log(Jg/Eo2x) vs. 1/Eox curves are given in Table I which illustrates the effects of RTN and RTO~ on the injecting barrier of the resulting polyoxides. RTO1 of poly-Si results in an increase of ~B,efr for both bias polarities due to the relatively smooth poly-Si/polyoxide interfaces (11,12). After nitridation, the calculated %,eft for both + Vg and -Vg decreases with RTN directly due to the incorporated nitrogen at both poly-Si/polyoxide interfaces.…”

Section: Effects Of Rapid Thermal Reoxidationmentioning

confidence: 98%

“…For instance, a high temperature annealing of POCI~ doped poly-Si with an optimum level of 6 • 102o cm -s prior to oxidation was demonstrated to improve the dielectric strength (9) and reduce the leakage current (10). On the other hand, it has been proposed (8) and demonstrated (11,12) that a smooth polyoxide/poly-Si interface could be achieved by a high temperature oxidation (e.g., 1050-1100~ which is predominantly diffusion-controlled. Furthermore, to improve the quality of polyoxide, furnace nitridation of polyoxides in pure NHa ambient (13) was applied and yielded the high dielectric breakdown field -14 MV/cm for films of 76 nm.…”

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confidence: 99%

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Current Conduction and Charge Trapping in Thin Interpoly Dielectrics Prepared by In Situ Multiple Rapid Thermal Processing

Cheung

Kwong

1992

J. Electrochem. Soc.

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In this paper we report a systematic and comprehensive study of the effects of post-oxidation anneals on the electrical properties of thin polyoxide films. Thin (---20 nm) interpoly dielectrics have been grown on phosphorus implanted polysilicon by in situ multiple rapid thermal processing (RTP) including rapid thermal oxidation (RTO1), rapid thermal nitridation (RTN), and subsequent rapid thermal reoxidation (RTO2). In comparison with polyoxides grown in conventional furnace, RTO~ polyoxides exhibit a significantly reduced leakage current. In addition, both the dielectric breakdown strength and breakdown field distribution have been improved. It is found that RTN of RTO1 results in polyoxides with an unusual polarity asymmetry dependence of electrical conduction and trapping properties, i.e., a higher electrical conduction and electron trapping rate for electrons injected from the top poly-Si electrode than for electrons injected from the bottom poly-Si electrode. Subsequent RTO2 of nitrided polyoxides results in a reduction of both the leakage current and electron trapping rate. Longer RTO2, however, increases the leakage current due to the progressively deteriorated poly-Si/ polyoxide interracial texture.Oxide films grown on n+-poly-Si (i.e. polyoxides) are essential for the development of nonvolatile memory applications such as EPROM and E~'PROM devices. The scaling of device geometries makes thinner polyoxides necessary in order to keep a high gate coupling ratio. Device performance is determined by its data retentivity and programming efficiency, in terms of the leakage current and dielectric strength. However, polyoxides usually exhibit higher leakage current and inferior dielectric strength in comparison with oxides of comparable thickness grown on single crystalline-Si, due to the asperities and bumps at the polyoxide/poly-Si interface which lead to a localized field enhancement (1-7). The "roughness" is attributed to the different oxidation rates of randomly oriented poly-Si grains in low temperature ranges where the interfacial reaction rate controls the oxidation kinetics (8) and the irregular grain growth during the poly-Si doping process (8). It has been found that the quality of polyoxides depends upon the poly-Si preparation, oxidation condition, and post-oxidation annealing. It is known that the poly-Si oxidation and the electrical characteristics of resulting polyoxides strongly depend on the smoothness of the poly-Si surface prior to oxidation, as well as the doping conditions (8). For instance, a high temperature annealing of POCI~ doped poly-Si with an optimum level of 6 • 102o cm -s prior to oxidation was demonstrated to improve the dielectric strength (9) and reduce the leakage current (10). On the other hand, it has been proposed (8) and demonstrated (11, 12) that a smooth polyoxide/poly-Si interface could be achieved by a high temperature oxidation (e.g., 1050-1100~ which is predominantly diffusion-controlled. Furthermore, to improve the quality of polyoxide, furnace nitridation of polyox...

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Section: Comparison Of Rapid Thermal Oxidation and Furnacesupporting

confidence: 74%

Section: Effects Of Rapid Thermal Reoxidationmentioning

confidence: 92%

Section: Effects Of Rapid Thermal Reoxidationmentioning

confidence: 98%

mentioning

confidence: 99%

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Current Conduction and Charge Trapping in Thin Interpoly Dielectrics Prepared by In Situ Multiple Rapid Thermal Processing

Cheung

Kwong

1992

J. Electrochem. Soc.

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“…Finally, the difference in refractive index may result from surface roughness created during the doping, annealing, and oxidation of poly (10,19,20). It has been shown that roughness at the Si-SiO2 interface can be modeled as an additional film at the interface with composite refractive index (21).…”

Section: Discussionmentioning

confidence: 99%

A Special Case of Using Ellipsometry to Measure the Thickness of Oxide on Polysilicon: II . Application

Vasquez

Tompkins

Gregory

1990

J. Electrochem. Soc.

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Experimental results presented in this work verify the application of a visible light single wavelength ellipsometric method for measuring the thickness of oxide on polysilicon (poly-ox). The method requires a special test structure with a thin oxide under the poly. These results confirm that the uncertainty of the poly-ox thickness determination is approximated by the thickness of the oxide under the polysilicon. Test structures were generated with 100A oxides under 5000A polysilicon. With the proper choice of the values of A ~ and ~~ for the film-free surface, the poly-ox thickness determined by ellipsometry using the single-film approximation agreed within 100A of the thickness measured by Auger electron spectroscopy. In the semiconductor manufacturing environment, poly oxidation processes are usually monitored with singlecrystal test wafers. Since the differential oxide thickness on poly relative to single-crystal depends on the several process conditions (poly deposition, doping, annealing, oxidation), the single-crystal monitors do not accurately represent the results on the polysilicon. The new method permits measurement of poly-ox thickness directly after oxidation and therefore accounts for the interaction of the previous process conditions with the conditions of oxidation that is so important to the resultant poly-ox thickness.

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The effect of gate electrodes using tungsten silicides and/or poly-silicon on the dielectric characteristics of very thin oxides

Cheng

Chao

Su³

et al. 1990

Solid-State Electronics

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Thin polyoxide films grown by rapid thermal processing

Cited by 8 publications

References 1 publication

Current Conduction and Charge Trapping in Thin Interpoly Dielectrics Prepared by In Situ Multiple Rapid Thermal Processing

Current Conduction and Charge Trapping in Thin Interpoly Dielectrics Prepared by In Situ Multiple Rapid Thermal Processing

A Special Case of Using Ellipsometry to Measure the Thickness of Oxide on Polysilicon: II . Application

The effect of gate electrodes using tungsten silicides and/or poly-silicon on the dielectric characteristics of very thin oxides

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