LOW HYDROGEN CONTENT STOICHIOMETRIC SILICON-NITRIDE FILMS DEPOSITED BY PLASMA-ENHANCED CHEMICAL VAPOR-DEPOSITION

被引:180
作者
PARSONS, GN
SOUK, JH
BATEY, J
机构
[1] IBM Research Division, T. J. Watson Research Center, Yorktown Heights
关键词
D O I
10.1063/1.349544
中图分类号
O59 [应用物理学];
学科分类号
摘要
We have deposited silicon nitride films by plasma-enhanced chemical vapor deposition (PECVD) at 250-degrees-C with properties similar to films prepared at 700-degrees-C by low-pressure chemical vapor deposition (LPCVD). Films are prepared using silane and nitrogen source gases with helium dilution. The film properties, including N/Si ratio, hydrogen content and electrical quality are most sensitive to changes in the silane flow rate during deposition. For films deposited under optimized conditions at a substrate temperature of 250-degrees-C, current versus voltage measurements in metal-insulator-semiconductor structures show the onset of carrier injection at 3-4 MV/cm, slightly lower than LPCVD films. When bias-stressed to 2 MV/cm, capacitance versus voltage measurements show some hysteretic behavior and evidence for positive fixed charge, similar to LPCVD films. For the optimized films: N/Si = 1.33 +/- .02; refractive index (lambda = 6328 angstrom) = 1.980 +/- 0.01; dielectric constant (1 MHz) approximately 7.5; density = 2.7 +/- 0.1; and the etch rate in 10% buffered HF ranges from 32 to 70 angstrom/min. In addition, the hydrogen is distributed equally in Si-H and N-H groups, with a total hydrogen content < 10 at.%. These films have a significantly lower hydrogen content than observed in other PECVD silicon nitride films deposited at this temperature. When the substrate temperature is increased to 350-degrees-C, the films have the same Si/N ratio, and similar electrical properties; the hydrogen content is reduced to < 6 x 10(21) cm-3, and the etch rate is 17 angstrom/s in 10% buffered HF solution.
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页码:1553 / 1560
页数:8
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