Influence of Mg on Resistivity, Adhesion, Agglomeration of Ag(Mg)/SiO 2 /Si Multilayers
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Influence of Mg on resistivity, adhesion, agglomeration of Ag(Mg)/SiO2/Si multilayers Bongjoo Kang1, Heejung Yang1, Sungjin Hong1, Yeonkyu Ko1, Chang-Oh Jeong2 and Jaegab Lee1. 1 School of Metallurgical and Materials Engineering, Kookmin University, Seoul, 136-702, Korea 2 Samsung Electronics Co.,LTD., R&D Team, AMLCD Division, Kiheung-Eup, Yongin-City, Kyunggi-Do, Korea ABSTRACT The effect of Mg in Ag(Mg)/SiO2/Si multilayers on adhesion, agglomeration, and resistivity
to 500 have been investigated. The annealing of after annealing in vacuum at 200 Ag(Mg)/SiO2/Si multilayers produced surface and interfacial MgO layers, resulting in MgO/Ag(Mg)/MgO/SiO2/Si structure. The presence of surface MgO provided the passivation against air, thus leading to the significantly enhanced resistance to agglomeration. In addition, the resistivity of Ag(Mg) film decreased by lowering Mg content and increasing the annealing temperature as well. Furthermore, Ag adhesion to SiO2 was improved due to the formation of the interfacial MgO layer resulting from the reaction of segregated Mg with SiO2. Also, the negligible solubility of Si in Ag prevented the dissolution of free silicon produced from the reaction, Mg + SiO2 = MgO + Si, which was in contrast with the dissolution of a significant amount of silicon released from the SiO2 substrate in Cu(Mg)/SiO2/Si multilayers after annealing
at high temperature, e.g., 400 . The dissolved Si in Cu caused the rapid increase in resistivity in Cu(Mg)/SiO2/Si. INTRODUCTION Recently, Ag has received attentions as a potential interconnection in ultra-large scale integration(ULSI)[1,2] and large area TFT/LCDs[3] because it shows the lowest resistivity among metals, high electromigration resistance[4], and high thermal conductivity[5]. In addition, no diffusion barrier is required to prevent reaction between Ag and Si in Ag/Si contact structures[3] because Ag is thermodynamically stable with Si and also has negligible solubility of Si. However, there are several issues that need to be addressed to implement Ag metallization as a interconnection of ULSI and large-area displays including poor adhesion to dielectrics, agglomeration[6] upon annealing in an oxygen ambient, Ag sulfidation (chlorination) in the corrosive environment[7], and difficulty with dry etching[2]. Among those issues, this work will focus on two crucial problems such as poor adhesion to SiO2 and agglomeration using an A9.9.1
Ag(Mg) alloying scheme. The doping of Ag with Mg was intended to grow the surface MgO layer to passivate Ag and to produce the interfacial MgO layer on SiO2 surface upon annealing. The formation mechanism of surface MgO and interfacial MgO layer will be described. Furthermore, the factors affecting the interfacial MgO reaction and its effects on the adhesion and resistivity of Ag(Mg) alloy films will be discussed. EXPERIMENTAL
Pure Ag and Ag(Mg) alloy films(2000 ) were deposited on SiO2(1000 ) coated wafers using DC magnetron sputtering from the target of Ag(10at.%Mg) with a purity of 99.99 %. Mg c
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