|關鍵字:||多孔性低介電常數材料;平坦化;漏電機制;與銅的可靠性;porous ultra low-k;CMP;leakage mechanism;reliability|
|摘要:||隨著半導體技術的進步，元件的尺寸不斷的縮小，電子訊號在金屬導線間傳遞所造成的延遲，變成半導體元件速度受限的主要原因。為了降低訊號傳遞的時間延遲，使用低介電常數材料作為導線間的絕緣層，便可降低導線間的電容值，使元件在速度方面的性能提高，並且可以降低功率的消耗(power dissipation)及雜訊干擾(cross-talk noise)。但是多孔性低介電常數材料的機械強度一般來說都較緻密的材料差，因此在平坦化製程整合上將面臨重大的考驗。
As ULSI circuits are scaled down to deep submicron regime, interconnect delay becomes increasingly dominant over intrinsic gate delay. To reduce the RC delay time, many low dielectric constant materials have been developed. However, the mechanical strength of porous low k materials is worse than that of dense materials. For process integration considerations, we will investigate the impacts of CMP (chemical mechanical polish) on electrical characteristics of porous dielectrics.. In this thesis, we will investigate the impacts of the CMP process with various slurries on the ultra low-k PPSZ-MTM (porous Methylsilsesquiazane). The dielectric characteristics are not degraded after three kinds of slurry treatment. In parallel, a novel oxygen plasma pre-treatment has been proposed in order to increase the polish rate of the ultra low-k PPSZ-M for the duration of CMP process. O2 plasma treatment can convert PPSZ-M surface from hydrophobic into hydrophilic. The hydrophilic surface can increase the reaction rate between PPSZ-M and chemical slurry during CMP process, resulting in the increase of CMP polish rate. Furthermore, it is found that the dielectric characteristics of O2 plasma-treated PPSZ-M after CMP process are similar to that of the as-cured PPSZ-M. As a result, O2 plasma pre-treatment has an extreme potential in the future IC fabrication. In addition, we have also explored the leakage mechanism of the PPSZ-M after the CMP process and the reliability issue related to copper penetration in porous silica film. The leakage mechanism of the O2 plasma-treated PPSZ-M is the ionic conduction. After the CMP process, the leakage current behavior transform from ionic conduction to Schottky-like mechanism. Under the high temperature and bias stress, the electrical characteristics are still not degraded. Consequently, the integration between PPSZ-M and CMP has extreme potential in the new generation of the ICs.
|Appears in Collections:||Thesis|