Abstract
一種新方法-以TiCl4及SiF2當先驅物，利用CVD方法沉積矽化鈦薄膜-已被發展出來。此法在TiCl4分壓為90mtorr，(SiF2+SiF4)分壓在90-150mtorr的條件下，可在400℃-850℃下沉積薄膜，其組成Si/Ti原子比約為2，經XRD測量為多晶型C54 - TiSi2結晶相。而400℃沉積之薄膜是目前使用低壓化學氣相沉積法沉積矽化鈦薄膜中，沉積溫度最低者。沉積過程中的氣體產物經鑑定，主要為SiF2Cl2、SiF3Cl、 SiF3SiFCl2、SiF2ClSiF2Cl。經由TiCl4及SiF2之CVD的反應過程:基本上可以看成TiCl4與SiF2在氣相中即形成中間體，此中間體在適當條件下會脫去鹵素，形成固態物質及各種鹵化矽烷。在本實驗中SiF2伴演二種角色:一為其與TiCl4進行反應後，形成中間體，而此中間體即是矽的來源者;二為其對此中間體作去氟及氯的反應，此時的SiF2則伴演清道夫之角色。A new method for depositing thin films of titanium silicide byusing difluorosilylene and titanium tetrachloride as precursorsof chemical vapour deposition has been developed. When thepartial pressures of TiCl4 and (SiF2+SiF4) were at 90mtorr and90-150mtorr respective, and the temperatures were at 400℃-850℃, the thin films were grown. The Si/Ti ratio of the films wasabout 2. XRD studies indicated that the films werepolycrystalline C54-TiSi2. 400℃ is the lowest depositiontemperature ever reported for the growth of TiSi2. Analysis ofthe gaseous products during the deposition process revealedthat SiF2Cl2,SiF3Cl,SiF3SiFCl2, SiF2ClSiF2Cl were the majorproducts. From the results of gas phase reaction, cocondensereaction and layer by layer reaction between TiCl4 and SiF2, wehave speculated the reaction process as below: gaseousintermidiate was formed from TiCl4 and SiF2 followed by theelimination of halogens to produce solid materials andhalosilanes under various conditions. SiF2 played two roles inthis experiment: one was the "silicon source" of the films andthe other was the "scavenger" of the excess fluorine andchlorine atoms.