| AVS 61st International Symposium & Exhibition | |
| Electronic Materials and Processing | Tuesday Sessions |
| Session EM-TuM |
| Session: | Advanced Interconnects and Materials |
| Presenter: | Nicolas Jourdan, IMEC, Belgium |
| Correspondent: | Click to Email |
To prevent copper diffusion in a circuit, commonly a PVD-TaN/Ta liner is formed on the dielectric surface as a diffusion barrier prior to Cu metallization. The integrity of the PVD-TaN/Ta barrier is expected to reach its limit at a trench dimension below 20nm width. As a result, alternatives must be found for further technology scaling. In recent years, Mn-based barriers have received great consideration as a thin self-formed MnSixOy diffusion barrier can be formed at the surface of the insulator without significant impact on the dielectric constant whilst preserving the total trench volume for Cu filling. Initially, such a “zero-thickness barrier’’ has been made using a PVD-CuMn seed layer, from which Mn atoms diffuse after a thermal anneal towards the surface of the insulator to form the diffusion barrier. However, because of the use of PVD, limited scalability of this option is expected. Therefore, CVD of Mn-based chemistries has been developed to enable the formation of a thin and conformal barrier [1, 2]. Such a layer has already been integrated in 2ML test vehicles (half pitch ranging from 40nm to 100nm) using a conventional scheme consisting of a PVD-Cu seed followed by Cu electroplating (ECD) and CMP. The authors reported significant RC reduction and comparable Time Dependent Dielectric Breakdown (TDDB) performance with respect to conventional PVD-TaN/Ta barrier [3]. However, integration of a thin Mn-based barrier faces a big challenge due to Mn dissolution taking place in the chemistries used in ECD and CMP operations. The impact of such a phenomenon is even more dramatic in narrow trenches used for advanced technology nodes due to the scaled PVD-Cu seed, which is no longer able to sufficiently protect Mn from dissolution.
In this work, we focus on the optimization of CVD Mn-based barrier in order to make it integration friendly. Furthermore, we will report on physical properties of such a barrier.
[1] N. Jourdan et al.: Electrochemical and Solid-State Letters 15 (5) (2012) H176-H178.
[2] Roy G. Gordon et al.: Proc. Advanced Metallization Conference, p. 1 (2008).
[3] Y. K. Siew et al., Proc. IEEE IITC 2013, p. 1.