Thin‐Oxide Dielectric Strength Improvement by Adding a Phosphonic Acid Chelating Agent into NH 4 OH ‐ H 2 O 2 Solution
Thin‐Oxide Dielectric Strength Improvement by Adding a Phosphonic Acid Chelating Agent into NH 4 OH ‐ H 2 O 2 Solution
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通过在 NH 4 OH - H 2 O 2 溶液中添加膦酸螯合剂提高薄氧化物介电强度
DOI：
10.1149/1.2059260
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发表时间：
1994
期刊：
影响因子：
--
通讯作者：
N. Yabumoto
中科院分区：
文献类型：
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作者：
H. Akiya;S. Kuwano;Tohru Matsumoto;H. Muraoka;M. Itsumi;N. Yabumoto
研究了在 NH4OH-H2O2-H20 湿法清洗溶液中添加螯合剂对硅表面金属污染的影响。虽然乙二胺四乙酸和其他众所周知的螯合剂已被证明只能将 Si 表面上的 Fe 吸附减少三分之一，但添加浓度仅为 1 ppm 的膦酸螯合剂可将 Fe 和 Ca 污染减少一个数量级以上，并提高 11 nm 薄氧化物的介电强度。超净晶圆加工在高密度、大规模集成电路 (LSI) 技术中非常重要。 MOS LSI 制造中使用的薄氧化膜介电强度特性的弱点通常归因于晶圆表面的金属污染物。 RCA 清洗是栅极氧化工艺中预清洗的常用方法，由两步湿法清洗循环组成。第一步，使用 NH4OH、H2O2 和 H2O 的混合物（称为 SC-1 溶液）去除 Si 表面上的颗粒和有机污染物。在第二步中，使用 HCl、H2O2 和 H2O 的混合物（称为 SC-2）去除金属污染物。安蒂拉埃塔/。 1 报告称，在 SC-1 处理过程中，Fe、Al 和 Zn 很可能被吸附到 Si 表面上。他们指出，吸附的 Fe 浓度取决于该溶液中使用的化学品的纯度，并建议在 H2O2 中添加一些螯合剂会减少这种吸附。 Verhaverbeke eta/。图 2 研究了故意引入的金属污染物与 MOS 电容器的薄栅极氧化物击穿强度之间的相关性。他们指出，大约 1012 个原子/cm 2 的 Ca、Al 和 Fe 会严重降低氧化物的质量。他们还观察到，在 SC-1 中添加乙二胺四乙酸 (EDTA) 可以改善氧化物击穿，同时降低 Si 表面粗糙度。然而，如本文后面所述，添加 1 ppm EDTA（或其他螯合剂）并没有显着减少 Si 上吸附的 Fe 量。村冈等人。 3报道称，含有某些膦酸基团的螯合剂可以大大减少铁的吸附，即使添加剂浓度低至1 ppm。
Effects of chelating agent additions to an NH4OH-H202-H20 wet cleaning solution are examined in terms of metallic contamination on Si surfaces. While ethylenediaminetetraacetic acid and other well-known chelating agents have been shown to reduce Fe adsorption onto an Si surface only by one third, adding a phosphonic acid chelating agent at a concentration of only 1 ppm reduces Fe and Ca contamination by more than one order of magnitude and increases dielectric strength of 11 nm thin oxide.Ultraclean wafer processing is important in high-density, largescale integrated circuit (LSI) technology. Weakness in the dielectric strength properties in thin oxide films used in MOS LSI fabrication has often been attributed to metallic contaminants on wafer surfaces. RCA-cleaning is a common method used for precleaning in the gate oxidation process, and consists of a 2-step wet cleaning cycle. In the first step, a mixture of NH4OH, H202, and H20 (called SC-1 solution) is used to remove particles and organic contaminations on Si surfaces. In the second step, a mixture of HCI, H202, and H20 (called SC-2) is used to remove metallic contaminants. Anttila eta/. 1 reported that Fe, AI, and Zn are likely to be adsorbed onto Si surfaces during SC-1 treatment. They noted that the concentration of adsorbed Fe depends upon the purity of chemicals used in this solution, and suggested that adding some chelating agents into H202 would reduce this adsorption. Verhaverbeke eta/. 2 investigated the correlation between intentionally introduced metallic contaminants and the thin gate oxide breakdown strength of MOS capacitors. They noted that Ca, AI, and Fe of approximately 1012 atoms/cm 2 can severely degrade the quality of oxides. They also observed that ethylenediaminetetraacetic acid (EDTA) additions to the SC-1 resulted in an oxide breakdown improvement along with a reduction of Si surface roughness As described later in this paper, however, the addition of 1 ppm EDTA (or other chelating agents) did not significantly reduce the amount of Fe adsorbed onto Si. Muraoka et al. 3 reported that chelating agents containing some phosphonic acid groups can greatly reduce Fe adsorption, even with additive concentrations as little as 1 ppm.