硬焊合金對矽晶片和鑽石膜之潤濕性研究

Abstract

本文是研究各種商業用焊料[CB1(Ag-Cu-Ti)、NiCr、B403(Ag-Cu-Zn-Ni) 、B450(Ag-Cu-Zn)和P616(Ag-Cu-In)]對矽晶片和鑽石膜之潤濕性。 研 究中所使用的鑽石膜是利用微波電漿沉積系統，以氫氣和甲烷為反應氣體 ，沉積在Si(100)、N型晶片上。 在可控制氣氛與溫度且附有光學量測系 統的直流電爐中，利用固定液滴法量測潤濕性。 硬焊合金潤濕特性是以 擴展面積、接觸角和液-氣相界面的表面張力為指標。 硬焊合金與基材 間可能的反應是由SEM、EDX、EPMA、XRD和Raman光譜技術來檢測之。 在硬焊合金處於非氧化狀態下的低露點氣氛中，CB1和NiCr硬焊合金對矽 晶片之最大接觸角與最小擴展面積值分別為40o和1.35cm2/g；對鑽石膜其 值分別為46o和1.53 cm2/g。 這兩種合金比其他硬焊合金具有如此高的 潤濕性是歸因於硬焊合金中高活性元素Ti和Ni會和基材產生強的化學鍵結 或形成固溶反應。 如果焊接時合金處於氧化的狀況下是不利且可能造成 失敗的接合。 高溫對於潤濕性的影響是由於其有降低液-氣相表面張力 的趨勢，使得接觸角降低。 此外，在相同的露點下，較高的溫度易於達 到非氧化氣氛狀態，但是有可能造成鑽石膜的石墨化，因而造成硬焊合金 對基材的潤濕性稍微的變差。 The wettabilities of various commercial brazing alloys [CB1(Ag- Cu-Ti) , NiCr , B403(Ag-Cu-Zn-Ni) , B450(Ag-Cu-Zn) , and P616( Ag-Cu-In)] to silicon wafer and diamond films were studied. Diamond films used for wettability study were deposited on Si(100) N-type wafer substrate by a microwave CVD system with H2 and CH4 as the source gases. Using the sessile drop method , the wettabilities were determined by a DC electrical furnace equipped with an optical system , and with an atmosphere and temperature control chamber. The wettabilies of brazing alloys are characterized by their spreading areas , contact angle , and surface tensions at the liquid- vapor interface. The possible interactions between the brazing alloys and the substrates were examined by SEM , EDX , EPMA , XRD and Raman spectroscopy. In case of the atmosphere with a lower enough dew point to maintain the brazing alloys under non-oxidizing conditions , the maximum contact angle and minimum spreading area for CB1 and Ni-Cr brazing alloys to Si wafer are 40 degree and 1.35 cm2/g , respectively ; and to diamond films are 46 degree and 1.53 cm2/g , respectively. This excellent wettability than other brazing alloys is contributed to greater reactivity and wettability of substrates with Ti and Ni atoms in the brazing alloys to form a stronger chemical bonding or solid solution . Brazing with alloys under oxidizing conditions can be detrimental or cause failure of bonding. Effect of high temperature on wettability is due to its effect in a decrease in the surface tension of the liquid-vapor interface , and so a decrease in the contact angle. Also , a higher temperature is favor to maintain a non-oxidizing condition at the same dew point level , but tend to cause the transformation of diamond substrate to graphite to slightly decrease the wettability of the brazing alloy.