Plasma Enhaced Chemical Vapor Deposition of Hydrogen-free SiO_2 using tera-isocyanate-silane

提出了利用等离子体增强化学气相沉积(PECVD)技术，利用四异氰酸酯-硅烷(Si(NCO)4：TiC)和氧气沉积二氧化硅的方法。该材料体系在沉积过程中不可能生成H_2O分子，也不可能产生羟基自由基。如果沉积的薄膜足够致密以防止水渗透到薄膜中，则薄膜在解决由于SiO_2层中的H_2O或OH自由基引起的通孔中毒和阈值电压变化问题方面具有很大的优势。薄膜的性能强烈地依赖于沉积气体的组成。在富氧和高温(300ﾟC)条件下沉积的薄膜是“无氢SiO_2”，即不含水，也不含OH基团。薄膜的密度、折射率、电阻率和介电常数分别为2.3g/cm~3、1.46、5×10~(-14)和3.6。缓冲HF的刻蚀速率为330 nm/min。薄膜质量随沉积温度的降低而降低，但沉积后在300ﾟC下进行热处理可改善薄膜质量。界面陷阱密度和固定电荷密度分别约为8×10^&lt；10&gt；cm^&lt；-2；ev^&lt；-1；和2*10^&lt；11&gt；cm^&lt；-2。此外还检查了氟的使用情况。折射率和介电常数分别降低了8%和3%。

Deposition of silicon dioxide by plasma-enhanced chemical vapor deposition (PECVD) technique using tetra-isocyanate-silane (Si (NCO) _4 : TICS) and oxygen for interlayr dielectric film application is proposed. This material system has an feature of no possibility of formation of H_2O molecules nor OH radicals during deposition. If deposited films were dense enough to prevent water penetration into the films, the films have a big advantage for solving the problem of poisoned via holes and threshold voltage variation because these were caused by H_2Oor OH radicals in SiO_2 interlayr. Film properties strongly depended on the deposition gas composition. The film which was deposited under an oxygen-rich condition and high temperature (300ﾟC) was "hydrogen-free SiO_2", which means that the films does not contaion water nor OH redicals. The film density, refractive index, resistivity, and dielectric constant were 2.3g/cm^3,1.46,5*10^<14>OMEGAcm, and 3.6, respectively. The etching rate by buffered HF was 330nm/min. The film quality degraded with decreasing deposition temperature, however, it can be improved by annealing at 300ﾟC after deposition. Interface trap density and fixed charge density were about 8*10^<10>cm^<-2>eV^<-1> and 2*10^<11>cm^<-2> respectively. Fluorine doping were also examined. Refractive index and dielectric constant were reduced by 8% and 3%, respectively.