Material Properties of a SiOC Low Dielectric Constant Film with Extendibility to k < 2.7

Abstract

A plasma deposited SiOC very low k (VLK) interlayer dielectric (ILD) film has been developed which can be tuned to 2.5 = k = 3.0, demonstrates very good thermal stability, excellent adhesion properties, acceptable hardness, and an indication that it may be extendible to k &lt; 2.5. This paper will disclose properties of this SiOC film which are important to a VLK ILD application.

Permittivity and Conductivity of Low-Dielectric-Constant SiOC:H Films Deposited by Plasma-Enhanced Chemical Vapor Deposition

“…Different groups have investigated the physicochemical properties of SiOC:H films deposited by radio-frequency ͑rf͒ PECVD. [3][4][5][6][7][8][9][10][11][12] Usually the gas precursor is a mixture of an organosilane ͑e.g., trior tetramethylsilane͒ and an oxidizing agent ͑e.g., oxygen or nitrous oxide͒. The atomic composition appears to be strongly dependent on deposition conditions.…”

“…The atomic composition appears to be strongly dependent on deposition conditions. A compilation of past works [3][4][5][6][7][8][9][10][11][12] leads to an average film composition of 25% silicon ͑min 9%, max 42%͒, 35% oxygen ͑min 13%, max 61%͒, 20% carbon ͑min 5%, max 26%͒, and 20% hydrogen ͑min 8%, max 46%͒. IR analysis performed by numerous authors indicates the presence of Si-O-Si bonds ͑dominant͒, Si-CH 3 and Si-C-Si bonds ͑usually strong͒, Si-H and C-H bonds ͑whose intensity depends on hydrogen content, but usually small͒.…”

“…Depending on deposition methods, the dielectric constant varies between ϭ 2.5 and 4, while the optical refractive index varies between n ϭ 1.4 and 1.6. [3][4][5][6][7][8][9][10][11][12] By introducing porosity it is possible to further lower the dielectric constant ͑down to 2͒ 13 as well as the refractive index ͑1.15͒. 14 However, although not explicitly reported, 13,14 it is likely that porosity leads to a degradation of other properties ͑chemical resistance and mechanical properties͒.…”

“…There have been a few detailed investigations 12 of the dielectric properties of SiOC:H ͑very often [3][4][5][6][7][8][9][10][11] information is limited to a value of the dielectric constant at 1 MHz and to a value of the leakage current at high fields͒. Kim and co-workers 12 studied the electronic, ionic, and dipolar contributions to the dielectric constant.…”