Method and device for measuring the thickness of thin films near a sample's edge and in a damascene-type structure

A method for measuring a structure comprising multiple thin, metallic, rectangular-shaped regions, each having a width of less than 1 micron and being disposed between neighboring regions comprising a second, non-metallic material, comprising:

• exciting acoustic modes in multiple metallic, rectangular-shaped regions by simultaneously irradiating the regions with a spatially periodic excitation field defined by a wavevector;
• detecting the acoustic modes by diffracting a probe laser beam off a ripple morphology induced in each of the regions by the acoustic modes;
• and
• analyzing the signal beam to determine an average thickness of the metallic, rectangular-shaped regions irradiated by the excitation field.

An apparatus for measuring a structure comprising multiple thin, metallic, rectangular-shaped regions, each having a width of less than 5 microns and being disposed between neighboring regions comprising a second, non-metallic material, comprising:

• at least one excitation laser beam aligned to irradiate the region with a spatially periodic excitation field defined by a wavevector to excite acoustic modes in at least one metallic, rectangular-shaped region;
• a probe laser beam that detects the acoustic modes by diffracting off a modulated optical or physical property induced in the regions by the acoustic modes to form a signal beam;
• and
• an analyzer that analyzes the diffracted signal beam to determine a property of the structure,
• wherein the analyzer is further configured to analyze the probe beam diffracted or reflected by the metallic, rectangular-based regions.

A method for measuring a thickness of a structure comprising multiple thin, metallic, rectangular-shaped regions, each having a width of less than 5 microns and being disposed between neighboring regions comprising a second, non-metallic material, comprising:

• measuring an acoustic property in a region of the structure;
• analyzing the acoustic property of the structure to determine a mass in the region of the structure;
• and
• calculating a thickness of the structure from the mass and a periodicity of the thin, metallic, rectangular-shaped regions.

A method for measuring a structure comprising a plurality of polygon-shaped metal portions, comprising the steps of:

• generating an excitation field;
• aligning the excitation field so that it simultaneously irradiates at least two of the polygon-shaped metal portions in a first region to excite an acoustic component;
• detecting the acoustic component by irradiating it with a probe laser beam to generate a signal beam;
• analyzing a feature of the signal beam corresponding to the acoustic component to determine a property of the structure in the first region;
• translating the structure or the excitation field and probe laser beam so that the excitation field simultaneously irradiates at least two of the polygon-shaped metal portions in a second region to excite an acoustic component;
• and
• repeating the excitation, detection, and analyzing steps to determine a property of the structure in a second region to determine position-dependent properties of the structure.