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首页> 外文学位 >Development of barrierless dielectrics and their integration with copper for nanodevice wiring.
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Development of barrierless dielectrics and their integration with copper for nanodevice wiring.

机译：无障碍电介质的开发及其与铜的集成，用于纳米器件布线。

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摘要

Future generation integrated circuits require the development and integration of new low dielectric permittivity (e.g., kappa∼2.5) materials with copper wiring such that the chemical and mechanical stability of the metal-dielectric interface are preserved. Introducing pores and/or including low electronic polarizability bonds such as Si-C, C-C and C-H are promising strategies to lower kappa dielectrics. Presently, 5-10 nm interfacial layers comprised of inorganic materials are used to inhibit metal and water intake into the dielectric, and enhance metal-dielectric adhesion. Recent work has shown that these features can be achieved using ultrathin (2 nm) molecular nanolayers, but integrating them with device processing schemes, or devising strategies to eliminate the interfacial layer altogether remain challenges.;This thesis investigates strategies to obviate the use of a separate barrier/glue layer for integrating low-k dielectrics with metals. This is a problem of fundamental importance because low polarizability groups in low-k materials bond poorly with metals, and lead to rapid metal diffusion. We study two approaches, namely, incorporating metal-/water-blocking and adhesion enhancing moieties in the dielectric during synthesis or processing, or exploiting interfacial reaction between the dielectric and the metal to inhibit copper diffusion and enhance adhesion. Mesoporous silica and carbosilane polymer serve as model systems for our investigations of the two approaches. This understanding provides insights that could enable the design of a new class of "barrierless" low-kappa materials with inherent resilience to metal and water uptake, and provide good adhesion with copper without the use of a separate interfacial layer.;Functionalizing mesoporous silica (MPS) with organosilanes having different chemical moieties can be utilized to tailor the chemical stability of MPS and Cu/MPS structures against water uptake and copper diffusion. We show that MPS functionalized with trimethyl and tetrasulfide organosilanes inhibit copper diffusion as well as water uptake, and increase the time for dielectric breakdown. The hydrophobic trimethyl termini inhibit moisture uptake while the use bis[3-(triethoxysilyl)propyl] tetrasulfide BTPTS is efficient in decreasing Cu-induced leakage currents. Our studies also show that the sequence of organosilane treatments can have a significant bearing on the roles of the individual organosilanes due to steric and chemical effects. For example, MPS films treated by trimethyl-chloro-silane(TMCS) followed by BTPTS organosilane treatment results in a film with a lower relative dielectric constant and one that is more stable against moisture-induced instabilities, compared with films functionalized in the reverse sequence. Our results reveal that surface passivation induced physical blocking of Cu ions is the dominant mechanism for copper immobilization by longer organosilane in MPS. The chemical moieties in the organosilane also contribute to copper immobilization but that contribution is significantly lower.;Incorporating organosilanes into MPS during synthesis of the dielectric by sol-gel processing can enhance the chemical and mechanical stability. For example, incorporating cyanide-terminated 2-cyano-ethyl-trimethoxysilane (CTS) organosilane into MPS during dramatically improves the time-to-failure of the CTS-MPS films and enhances both the hardness and the modulus of the film. The reduced water uptake due to hydrophobic tails combined with surface passivation and chemical interaction by cyanide moieties improves the copper immobilization and enhances the electrical stability. Thus, a one step functionalization MPS by an organosilane with a suitable backbone and chain length by in-situ or post deposition technique can be utilized to enhance the diffusion barrier properties and/or mechanical properties of mesoporous silica films.;Another key finding in this thesis is that Cu oxide surface catalyzes the crosslinking of cyclolinear polycarbosilane (CLPCS), a low-kappa polymeric precursor, containing disilacyclobutane rings, leading to a thermoset film adherent to the copper surface. Additionally, crosslinking occurs at a higher rate at lower temperatures ∼160°C compared to those on oxidized Si or Al surfaces, providing a means to selectively form the dielectric on copper. Air curing of the CLPCS polymer on copper results in excellent interfacial toughness due to PCS-O-Cu bridges formed by the catalytic opening of disilacyclobutane rings in PCS by oxygen bound to the copper surface. Vacuum curing also promotes catalytic ring opening and crosslinking, but the formation of metallic Cu(0) by surface oxide reduction precludes the covalent anchoring of the opened moieties to the metal surface. These results, combined with earlier studies showing low-kappa values of the CLPCS films, their impermeability to copper intake and aggressive chemical treatments offer attractive possibilities for integrating carbosilane-based dielectrics directly with copper, without a diffusion barrier or adhesion layer. The results from this thesis are of importance for developing low-kappa materials with intrinsic/inherent diffusion barrier and/or adhesion properties.
机译：下一代集成电路需要开发和集成具有铜布线的新的低介电常数（例如，kappa ＜〜2.5）材料，从而保持金属-电介质界面的化学和机械稳定性。引入孔和/或包括低电子极化率的键（例如Si-C，C-C和C-H）是降低kappa电介质的有前途的策略。目前，由无机材料组成的5-10nm界面层用于抑制金属和水进入电介质中，并增强金属-电介质的粘附性。最近的工作表明，使用超薄（<2 nm）分子纳米层可以实现这些功能，但是将它们与器件处理方案集成在一起，或者设计出消除界面层的策略仍然是一个挑战。单独的阻挡层/胶层，用于将低k电介质与金属集成在一起。这是根本重要的问题，因为低k材料中的低极化率基团与金属的键合不良，导致金属快速扩散。我们研究了两种方法，即在合成或加工过程中在电介质中引入金属/水阻滞和增粘部分，或者利用电介质和金属之间的界面反应来抑制铜扩散并提高粘着力。介孔二氧化硅和碳硅烷聚合物是我们研究这两种方法的模型系统。这种理解为我们提供了见识，使他们能够设计出一种新型的“无障碍”低kappa材料，其对金属和水的吸收具有固有的回弹力，并且在不使用单独的界面层的情况下提供了与铜的良好粘合性。具有不同化学部分的有机硅烷的MPS）可用于调整MPS和Cu / MPS结构对水吸收和铜扩散的化学稳定性。我们表明，用三甲基和四硫化物有机硅烷官能化的MPS抑制了铜的扩散以及水的吸收，并增加了电介质击穿的时间。疏水的三甲基末端抑制水分吸收，而使用双[3-（三乙氧基甲硅烷基）丙基]四硫化物BTPTS可以有效降低Cu引起的泄漏电流。我们的研究还表明，由于空间和化学作用，有机硅烷处理的顺序可能对各个有机硅烷的作用有重要影响。例如，与以相反顺序进行功能化的薄膜相比，经三甲基氯硅烷（TMCS）和BTPTS有机硅烷处理的MPS薄膜相对介电常数较低，并且对潮气引起的不稳定性更稳定。 。我们的结果表明，表面钝化诱导的铜离子物理阻断是MPS中较长的有机硅烷将铜固定的主要机理。有机硅烷中的化学部分也有助于铜的固定化，但这一贡献要低得多。通过溶胶-凝胶工艺在介电合成过程中将有机硅烷掺入MPS可以增强化学和机械稳定性。例如，在过程中将氰化物封端的2-氰基乙基-三甲氧基硅烷（CTS）有机硅烷掺入MPS可以极大地改善CTS-MPS薄膜的失效时间，并提高薄膜的硬度和模量。由于疏水性尾部以及表面钝化和氰化物部分的化学相互作用而导致的水吸收减少，改善了铜的固定性并增强了电稳定性。因此，可以利用通过原位或后沉积技术通过具有合适的主链和链长的有机硅烷的一步官能化MPS，来增强介孔二氧化硅膜的扩散阻挡性能和/或机械性能。本文的观点是，氧化铜表面催化了含有二硅环丁烷环的低κ聚合物前体环线性聚碳硅烷（CLPCS）的交联，从而导致热固性薄膜粘附在铜表面。此外，与在氧化的Si或Al表面上相比，在较低的温度（约160°C）下以更高的速率发生交联，从而提供了一种在铜上选择性形成电介质的方法。由于PCS-O-Cu桥是由PCS中的二硅环环丁烷环通过结合在铜表面的氧催化打开而形成的，因此PC上的CLPCS聚合物在空气中空气固化会产生出色的界面韧性。真空固化还促进了催化环的打开和交联，但是通过表面氧化物还原形成金属Cu（0）排除了将打开的部分共价锚定到金属表面的可能性。这些结果与早期研究相结合，显示出CLPCS膜的低kappa值，它们的抗铜吸收性和积极的化学处理为将碳硅烷基电介质与铜直接集成而没有扩散阻挡层或粘附层提供了诱人的可能性。本论文的结果对开发具有固有/固有扩散阻挡和/或粘附特性的低κ材料具有重要意义。

著录项

  • 作者

    Singh, Binay Kumar.;

  • 作者单位

    Rensselaer Polytechnic Institute.;

  • 授予单位 Rensselaer Polytechnic Institute.;
  • 学科 Engineering Chemical.;Engineering Electronics and Electrical.;Engineering Materials Science.
  • 学位 Ph.D.
  • 年度 2009
  • 页码 154 p.
  • 总页数 154
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

  • 入库时间 2022-08-17 11:38:19

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