Amorphous carbon based materials as the interconnect dielectric in ULSI chips
Amorphous carbon based materials as the interconnect dielectric in ULSI chips
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DOI：
10.1016/s0925-9635(00)00473-8
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发表时间：
2001-02-01
影响因子：
4.1
通讯作者：
Grill, A
中科院分区：
文献类型：
--
作者：
Grill, A
ULSI芯片中器件和布线尺寸的缩小与互连金属化的电阻增加以及级间和级内电容的增加相关，从而导致相应的更长的信号延迟。为了降低这些电容和改善未来ULSI电路的开关性能，需要低介电常数(K)绝缘体，其中k明显低于目前使用的SiO_2绝缘体。在ULSI电路中集成低k绝缘体也将减少操作它们所需的功率。类金刚石碳(DLC)具有优异的力学、摩擦学、光学和耐化学性能，具有广泛的应用前景。这种薄膜也是介电材料，在低场下的电阻率可以达到10(16)欧姆-厘米。DLC类材料由于其各向同性的性质和通过等离子体辅助CVD技术沉积它们的能力而成为吸引人的介电材料。然而，具有钻石性质的非晶态碳材料的介电常数不低于SiO_2的介电常数(k=4)。研究发现，通过调节等离子体沉积的氢化类金刚石(a-C：H)的沉积条件，可以将其介电常数降低到>；3.3到2.7之间。在ULSI结构中加入低k材料对它们提出了大量必须满足的要求，其中包括在400℃的加工温度下的稳定性。而具有介电常数k>；3.3的DLC薄膜在400℃惰性气氛中经4h的热处理后表现出较好的稳定性，热稳定性随介电常数的降低而降低。在FDLC薄膜中掺入氟会产生一种热稳定性明显更高的材料，并进一步降低介电常数，甚至低于2.4。沉积的Low-k DLC或FDLC薄膜可以通过初始退火在尺寸稳定性和材料损失方面热稳定，这也导致DLC类型材料典型的本征薄膜应力显著降低。低k膜在互连结构中的集成还要求与与低k电介质接触的材料具有良好的热稳定界面粘附性。这种材料可以包括加工助剂和结构部件，如氮化硅或氧化物，以及线材包层冶金。本文讨论了Low-k DLC和FDLC薄膜的制备和表征，它们的热稳定性方法，以及集成问题的评估。(C)2001 Elsevier Science B.V.保留所有权利。
The shrinkage of the devices and wiring dimensions in the ULSI chips is associated with an increased resistance of the interconnect metallization and increased interlevel and intralevel capacitances, causing corresponding longer signal delays. Low dielectric constant (k) insulators, with k significantly lower than that of presently used SiO2 are needed for reducing these capacitances and improving the switching performances of future ULSI circuits. Integration of low-k insulators in the ULSI circuits will also reduce the power required to operate them. Diamond-like carbon (DLC) has found a variety of applications based on its attractive mechanical, tribological, optical and chemical resistance properties. The films are also dielectrics whose electrical resistivities can reach values of 10(16) Omega -cm at low fields. The DLC-type materials are attractive dielectrics because of their isotropic properties and the ability to deposit them by plasma assisted CVD techniques. However, the amorphous carbon materials with diamond-like properties are characterized by dielectric constants that are not lower than that of SiO2 (k = 4). It was found that, by adjusting the deposition conditions of plasma deposited hydrogenated DLC (a-C:H), it is possible to reduce its dielectric constant to values between > 3.3 and 2.7. Incorporation of the low-k materials in the ULSI structures imposes a significant number of requirements that they have to satisfy, among them stability at the processing temperature of 400 degreesC. While DLC films having dielectric constants k > 3.3 appeared to be stable to anneals of 4 h at 400 degreesC in inert ambiance, the thermal stability decreased with decreasing dielectric constant. Incorporation of fluorine in FDLC films produces a material of apparently higher thermal stability and further reduced dielectric constants, to values even lower then 2.4. The as-deposited low-k DLC or FDLC films may be thermally stabilized, in terms of dimensional stability and material loss, by an initial anneal, that also causes a significant reduction in the intrinsic film stress, typical of DLC type materials. The integration of the low-k films in the interconnect structures further requires good adhesion with thermally stable interfaces to materials in contact with the low-k dielectric. Such materials may include processing aids and structural components such as silicon nitride or oxide, and wire cladding metallurgy. The paper discusses the preparation and characterization of the low-k DLC and FDLC films, approaches for their thermal stabilization and evaluation of integration issues. (C) 2001 Elsevier Science B.V. All rights reserved.