Observation and control of the interfacial reaction of multilayr thin films for lead bonding wire using optical reflectivity technique.

用X射线衍射法和光学反射率法研究了在100~250ﾟC温度范围内热处理的Al/Au和Al/Cu薄膜对金属间化合物相的形成。首先在SiO_2上沉积厚度为100 nm的Au或Cu金属，然后在真空中在Au或Cu膜上制备出厚度为100 nm的Al薄膜。经X-射线分析证实，退火后形成了几种金属间化合物。通过光学反射率随波长的变化可以观察到Al2CuAlCuAl2AU的形成和生长。金属在Al/Au薄膜中的互扩散比在Al/Cu薄膜中的互扩散更快。例如，在200ﾟ℃下热处理的Al_2AU和Al_2Cu薄膜对的生长速率常数(K)分别为3.4×10~(-6)和2.4×10~(-7)cm/s~(-1)。这些金属间化合物层在薄膜中的生长速度比在大块金属扩散偶中的生长速度更快。用压痕试验研究了Al和Cu界面反应产物的强度。强度随反应时间和反应区厚度的增加而迅速增加，然后降低。合适的界面反应区厚度有助于提高铝铜引线的强度。

Formation of intermetallic phases in Al/Au and Al/Cu thinfilm couples annealed at temperatures between 100ﾟC and 250ﾟC has been investigated using X-ray diffraction and optical reflectivity technique. The Au or Cu metals with the thickness of 100nm were first deposited on SiO_2 plate and then Al thin film with the thickness of 100nm was produced on the Au or Cu film in vacuum. Formation of several intermetallic compounds was confirmed by X-ray analysis after annealing. The formation and growth of Al_2Cu, AlCu and Al_2Au could be observed by the variation of optical reflectivity with wavelength. The inter-diffusion of metals in Al/Au thin film occurred faster than that in Al/Cu during annealing. For example, the growth rate constants (k) of Al_2Au and Al_2Cu layrs in thin film couples annealed at 200ﾟC were 3.4x10^<-6> and 2.4x10^<-7> cm/sec^<1/2>, respectively. The growth rate of these intermetallic layrs was faster in thin films than in diffusion couples of bulk metals.The strength of interfacial reaction products between Al and Cu was investigated using indentation test. The strength increased rapidly with increasign time and thickness of reaction zone, and then decreased. An appropriate thickness of the reaction zone at the interface contributed to the improvement of the strength of Al-Cu lead bonding wires.