Motorola Corporation

Larry E Frisa

Karl Emerson Mautz

Hak-Lay Chuang

Laura Pressley

The present invention relates to a method of determining a thickness of at least one layer on at least one semiconductor wafer ( ), comprising the steps of: projecting a first laser pulse ( ) on a surface ( ) of the at least one layer ( ), thereby generating an acoustical wave due to heating of the surface of the at least one layer ( ); after a propagation time of the acoustical wave, projecting a series of second laser pulses ( ) on the surface ( ) of the at least one layer ( ); measuring reflected laser pulses ( ) of the second laser pulses ( ), thereby sensing the times of reflection property changes of the surface ( ) of the at least one layer ( ); and determining the thickness of the at least one layer ( ) by analyzing the times of reflection property changes. The present invention further relates to a system for determining a thickness of a layer ( ) on a semiconductor wafer ( ).

Method and system for determining a thickness of a layer

A method for forming an interconnect structure on a semiconductor wafer (114) begins by placing the wafer (114) in a process chamber (100). The process chamber (100) contains a titanium (Ti) target (102) having a thin titanium nitride (TiN) layer (104) formed thereon. An argon-based plasma (106) is used to sputter the layer (104) off of the target (102) and onto a top surface of the water (114) to form an Argon Uniquely Sputtered Titanium Nitride (AUSTiN) layer (116) which has a nitrogen concentration gradient therethrough. After forming the layer (116), an argon-nitrogen plasma (107) is initiated to reform the titanium nitride (TiN) layer (104) on the target and complete the interconnect structure by forming a top stoichiometric or near stoichiometric titanium nitride layer (118) over the layer (116).

Method of forming an interconnect structure with a graded composition

A via 42 is formed in an ILD layer 40 of a semiconductor device 30, using an etch chemistry which is highly selective to an underlying transition metal oxy-nitride film 38. In one form, film 38 is a TiO.sub.x N.sub.y film which is graded in nitrogen and oxygen concentration, being nitrogen rich at the bottom and oxygen reach at the top of the film. One method for forming TiO.sub.x N.sub.y is to sputter deposit a titantium layer 34 onto the semiconductor device using a titanium target 52. Using the same target, a TiN layer 36 is deposited by flowing nitrogen into the deposition chamber. Consequently, a TiN layer 58 is deposited onto target 52. The TiN layer 58 is then sputtered off the target onto the semiconductor device until eventually pure titanium is again being sputtered onto the device. The resulting deposited film has a grade titanium concentration, which is then oxidized to form the graded TiO.sub.x N.sub.y film.

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Cedar Park, TX, United States of America

Larry E Frisa