非晶質碳化矽薄膜之電漿處理在銅內連線上之電性研究

Abstract

在銅的雙鑲嵌內連線技術上，介電材料被應用在銅的擴散阻障和蝕刻停止層上。SiN由於它的擴散阻障性質佳，被用來當作銅的擴散阻障層已是不二人選。但是SiN有很高的介電常數大約為7.2，此介電常數會增加內介電層的時間延遲效應。以a-SiC:H為低介電常數的擴散阻障層和蝕刻停止層，並已經將其應用在銅的鑲嵌技術上了。 先以CH4和SiH4為反應氣體，用電漿輔助氣相沈積系統來沈積薄膜，我們固定CH4氣體的流量並改變SiH4氣體的流量來分析SiH4氣體對膜材性質的影響，並探討氫氣和氨氣氣體電漿對膜材的影響。 結果顯示當SiH4氣體流量增加時，膜材的介電常數也隨著增加，當氣體流量為5 sccm時其介電常數值最低可至3.6。研究發現a-SiC:H薄膜藉由氫氣和氨氣的電漿處理都使得其漏電流下降。但氨氣電漿處理會使得介電常數值隨著電漿處理時間的增加而增加，而氫氣電漿處理並不會增加其介電常數值。

In copper dual damascene interconnects, the dielectric material is embedded with a copper diffusion barrier and an etch stop. The barrier is usually silicon nitride because of its good barrier properties to copper diffusion. However, silicon nitride suffers from a high dielectric constant, around 7.2. This high dielectric value increases the overall inter-level dielectric（ILD） time delay. a-SiC:H as a low k dielectric barrier/etch stop layer has been developed for use in copper damascene application. The film is deposited using methane（CH4） and silane （SiH4）as precursors in a plasma enhanced chemical vapor deposition（PECVD）reactor. In order to analyze the effect of silane plasma conditions on the material properties, set of sample were grown with identical methane concentrations but with different silane flows. We also studied the effects of H2 and NH3 plasma treatment. As a result, the dielectric constant is increased as the silane gas flow is increased. The film has a low dielectric constant of 3.6 when the silane gas flow was 5 sccm. The leakage current density of a-SiC:H decrease by the H2 and NH3 plasma treatment. The film with NH3 plasma treatment that the dielectric constant increased as the NH3 plasma treatment time is increase. H2 plasma treatment cannot increase the dielectric constant