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A Method for Physical Vapor Deposition of Films with Low Damage

IP.com Disclosure Number: IPCOM000012805D
Original Publication Date: 2003-May-28
Included in the Prior Art Database: 2003-May-28
Document File: 3 page(s) / 25K

Publishing Venue

Motorola

Related People

Da Zhang: AUTHOR [+4]

Abstract

Physical vapor deposition (PVD) technology for thin film formation in semiconductor device fabrication is advantageous in that much lower impurity level is induced as compared to its ALD or CVD counterparts. However one critical issue limiting its wide application in the front end is the sputter damage caused by plasma ions. The current invention overcomes the problem by applying a PVD process with a helium plasma ignition followed by a helium dilution. As helium ion is free of sputtering damage capability due to its extremely low ion mass, the invention significantly reduces damage at the interface of the deposited film and the substrate.

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Title:        � � A Method for Physical Vapor Deposition of Films with Low Damage

Author: Da Zhang, Bich-Yen Nguyen, Srikanth Samavedam, Jamie Schaeffer

Abstract:

� � � � � � � � � � � Physical vapor deposition (PVD) technology for thin film formation in semiconductor device fabrication is advantageous in that much lower impurity level is induced as compared to its ALD or CVD counterparts.� However one critical issue limiting its wide application in the front end is the sputter damage caused by plasma ions.� The current invention overcomes the problem by applying a PVD process with a helium plasma ignition followed by a helium dilution.� As helium ion is free of sputtering damage capability due to its extremely low ion mass, the invention significantly reduces damage at the interface of the deposited film and the substrate.

Body:

Physical vapor deposition (PVD) technology for thin film formation in semiconductor device fabrication is advantageous in that much lower impurity level is induced as compared to its ALD or CVD counterparts.� In the fabrication of metal gate for CMOS devices, where impurities in the deposited metal film significantly degrade the device performance and the stability of the process, a PVD solution therefore seems promising.� However, in conventional PVD, it is generally true that a sputtering damage is resulted at especially the interface of the deposited film (e.g., TiN) and the substrate (e.g., MOS SiO2 dielectric).� Appearances of sputtering damage include the presence of a large magnitude of fixed charge in the film stack, thinning of the substrate film, and a rough interfacial morphology.� These damage effects deteriorate the proper functionality of the device with the deposited film.� For example, large fixed charge leads to large swing of the threshold voltage of the MOS device, and an unpredictable thinning of MOS dielectric deviates the device performance from the initial design.� In such, mitigating sputtering damage is the key to redeem PVD as a favorable deposition approach for device fabrication.

Two folds of mechanisms are attributed to the introduction of sputtering damage during a conventional PVD process.� The first is the damage during the ignition of the plasma.� A conventional PVD process utilizes gas sources with heavy masses, and an example is the combination of Ar and N2.� During ignition or initiation of the plasma which lasts a time on the order of second, a large spike of the target voltage and plasma potential takes place.� This condition provides extremely high ion energy to those initial ions striking the wafer.� As the ion masses are close to that of the wafer material, wafer sputtering yield from these high energy ions...