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Method and System Developing a Hybrid Contact Via (CA) Plug without Seams/Voids using Electroplating

IP.com Disclosure Number: IPCOM000239407D
Publication Date: 2014-Nov-05
Document File: 5 page(s) / 123K

Publishing Venue

The IP.com Prior Art Database

Abstract

A method and system is disclosed for developing a hybrid Contact Via (CA) plug without seams / voids using electroplating.

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Method and System Developing a Hybrid Contact Via (CA) Plug without Seams/Voids using Electroplating

Disclosed is a method and system for developing a hybrid Contact Via (CA) plug without seams / voids using electroplating.

In an embodiment, a tungsten (W) CA is replaced with a hybrid CA structure of Atomic Layer Deposition (ALD) deposited W and an electroplated metal such as Copper (Cu) or Silver (Ag). Here, after Ti/TiN and PNLxT-H (pulsed nucleation layer of W, 24A) cool fill W (30A at 300C) is deposited as illustrated in Fig. 1.

Figure 1

Thereafter, metal seeds are deposited to electroplate a high aspects ratio plug. Fig. 2 illustrates the hybrid CA structure of ALD-deposited W and electroplated metal.

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Figure 2

In the above method, the ALD TiN process could be replaced by an optimized nitridation process of Ti layer in-situ using plasma annealing to get better TiN stoichiometry.

In accordance with the embodiment, the method and system utilizes a W layer in addition to the TiN barrier layer. Since, W is a high temperature (3422oC) refractory metal as compared to Cu (1084.87 oC) or Ag (961.8 oC), it can be worked as a double barrier layer to Cu diffusion. For such a structure, the resultant CA resistance can be a sum of resistance from TiN, Ti, W, Cu1-xWx precipitation / alloy and Cu or Ag. The resultant CA resistance is given by:

RCA = RTiN + RTi + RW + RCu1-xWx + RM

wherein M is Ag or Cu metal. The resultant CA resistance is expected to be at least equivalent or less than current CA contact resistance.

In another embodiment, the W CA is replaced with a hybrid CA structure of phosphorized W and electroplated Cu. Here, after nitride barrier and Ti oxygen getter liner are formed, cool fill CVD-W is deposited (300C process for 10-30A W) as illustrated in Fig. 3.

Figure 3

In the earlier step, TiN can be deposited using ALD process or formed in-situ by plasma

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nitridation of Ti layer. Subsequent to the cool fill CVD-W deposition, follows an ALD process of PNLxT-H (pulsed nucleation layer of W, ~10-25A). Then, few monolayers of the tungsten layer of 20- 55A are phosphorized (to form Tungsten Phosphide). Subsequently, a metal seed is deposited for plating high aspect ratio plugs.

Fig. 4 illustrates the hybrid CA structure of phosphorized W and electroplated Cu.

Figure 4

In the above method, the phosphide works as an additional Cu diffusion barrier layer. Here, Tungsten Phosphide (WxPy) is a key structure to prevent the diffusion of Cu or Ag. The phosphorous in Tungsten Phosphide layer can potentially bond with the metal seed during annealing to enhance adhesion of metal to the Liquid Natural Rubber (LNR).

The phosphedization of few monolayers of W...