化學氣相沈積氮化鉭與矽化鎳之同擴散阻絕特性探討

Abstract

本論文主要包括兩部分：第一部分是化學氣相沈積系統的組建以及氮化鉭薄膜的化學氣相沈積，第二部分是ITS製程所得Cu/NiSi/p+n淺接面二極體中的矽化鎳(NiSi)對同金屬擴散的阻絕特性探討。由於化學氣相沈積具有較佳的填洞能力，化學氣相沈積氮化鉭被認為是一種具有潛力的銅導線擴散阻絕層。本論文首先自行組裝一部備有DLI裝置(液態先驅物直接注入系統)的低壓化學氣相沈積系統，並且據以運用一種液態的有機金屬複合體 TBTDET 作為先驅物進行氮化鉭之化學氣相沈積，並探討其當作銅擴散阻絕層的熱穩定性。實驗結果顯示厚度50nm的化學氣相沈積氮化鉭薄膜經過600oC、30分鐘的常壓氮氣環境退火後仍能有效阻擋銅的擴散。在矽化鎳當作銅金屬擴散阻絕層的熱穩定性探討方面，實驗結果顯示以ITS製程所得Cu/NiSi(31nm)/p+n淺接面二極體在400oC常壓氮氣環境中30分鐘仍可有效阻擋銅的擴散。而其中以能量35keV，劑量5×1015cm-2之BF2+離子佈值後以650oC、30秒之快速退火(RTA)製程所得之Cu/NiSi(31nm)/p+n淺接面二極體可以承受30分鐘的450oC熱處理，而其反偏壓5伏特之漏電流密度仍然低於1uA/cm2。

This thesis study consists of two parts. The first part is mainly the construction of a low pressure chemical-vapor-deposition (CVD) system for the deposition of TaN films to be used as copper diffusion barrier. The second part is the investigation of the thermal stability and diffusion barrier property of NiSi in the Cu/NiSi/p+n shallow junction diodes formed by ITS scheme. The CVD-TaN film is regarded as a potential adhesion/diffusion-barrier layer for Cu interconnection scheme because of the superior via-filling capability of CVD film. In this study, a LPCVD system equipped with a DLI (direct liquid injection) sub-system was first built, followed by CVD-TaN films deposition using a higher precursor of TBTDET. Material analyses indicate that the deposited CVD-TaN film of 50nm thickness was capable of acting as diffusion barrier against Cu permeation up to a 600oC annealing for 30min in N2 ambient. Regarding the study on the thermal stability and diffusion barrier property of NiSi, we found that fluorine (F) incorporation in NiSi through BF2+ implantation significantly improved the thermal stability of NiSi film and that the Cu/NiSi(31nm)/p+n junction diodes fabricated by ITS scheme were able to sustain a 400oC thermal annealing in N2 ambient for 30min without degrading the diodes characteristics. In particular, the TaN/Cu/NiSi(31nm)/p+n junction diodes processed with BF2+ implantation at 35keV to a dose of 5×1015cm-2 followed by RTA at 650oC were able to maintain a reverse bias leakage current density less than 1uA/cm2 after a 30min thermal annealing at 450oC.