AVS 52nd International Symposium
    Thin Films Tuesday Sessions
       Session TF-TuA

Paper TF-TuA6
Novel ALD Reactor Design and Metrology Study for Tungsten ALD Process

Tuesday, November 1, 2005, 3:40 pm, Room 306

Session: Atomic Layer Deposition - Metals
Presenter: W. Lei, University of Maryland
Authors: W. Lei, University of Maryland
L. Henn-Lecordier, University of Maryland
G.W. Rubloff, University of Maryland
Correspondent: Click to Email
We have developed a novel wafer-scale atomic layer deposition (ALD) reactor which incorporates small reaction volume for short cycle time, multi-mode operation for process flexibility, and in-situ chemical sensing for rapid process learning and control. A movable cap within the UHV chamber enables transfer and enclosure of the wafer within a 0.2 L mini-reactor. Operation is possible using steady-state flow with alternating gas species or using fill-and-pumpout cycling of each gas with pumpout acceleration by lifting the cap to employ the larger reactor volume as ballast. Downstream in-situ mass spectrometry (MS) provides direct process sensing. By integrating reaction product MS signal over each exposure, we are able to observe nucleation and linear film growth stages of ALD film growth and study nucleation kinetics under different process and initial surface conditions, which indicated the application of in-situ MS for advanced process control in ALD process. First wafer effects in in-situ MS sensing are apparent when a sequence of wafers are processed, particularly when time delays are introduced between wafers; this is attributed to concurrent reaction on mini-reactor walls, where different gas exposure history is encountered. Advanced process control can be improved by proper pre-process reactor treatment to reduce first wafer effect.