Apparatus and method for performing thin film layer thickness metrology by deforming a thin film layer into a reflective condenser

An apparatus for measuring the thickness of a layer of material having a front and rear surface, wherein said layer is one of a possible plurality of layers each having a front and a rear surface and formed on a front surface of a substrate, and wherein said material of said layer has properties that allow light to be transmitted therethrough, said apparatus comprising:

• means for deforming said layer of material, said possible plurality of other layers, and said substrate, such that a reflective condenser is formed from said front and rear surface of said layer of material, said front and rear surfaces of said possible plurality of other layers, and said front surface of said substrate;
• means for providing a beam of collimated light;
• means for converting said beam of collimated light into a beam of collimated monochromatic light;
• means for focusing said beam of collimated monochromatic light so as to irradiate an entire front surface of said reflective condenser, said focused monochromatic light being reflected off said front and rear surfaces of said layer of material and said front and rear surfaces of said possible plurality of other layers and said front surface of said substrate, said reflected light interacting to form an interference fringe pattern image that is contained in a reflected monochromatic light beam;
• means for directing said reflected monochromatic light beam onto a detector array of a charge coupled device camera so as to display said contained interference fringe pattern image, said camera providing an output corresponding to said displayed interference fringe pattern image that has been detected by said array;
• means for digitizing said output of said charge coupled device camera;
• and
• means for receiving said digitized output of said charged coupled device camera and comparing said digitized output of said charge coupled device camera with stored reference reflectance data and providing an output corresponding to the thickness of said layer of material.

A method for measuring the thickness of a layer of material, said method comprising the steps of:

• providing a layer of material having front and rear surfaces, said material of said layer having properties that allow radiation to be transmitted therethrough;
• deforming said layer of material into a reflective condenser;
• irradiating said front surface of said deformed layer of material with monochromatic radiation, wherein said monochromatic radiation is reflected from said front and rear surfaces of said deformed layer of material having characteristics corresponding to the thickness of said layer of material;
• receiving said reflected radiation;
• detecting said characteristics of said received reflected radiation;
• comparing said detected characteristics of said received reflected radiation with a set of reference characteristics corresponding to known thicknesses;
• and
• providing an output corresponding to the thickness of said layer of material based on said comparison of said detected characteristics with said set of reference characteristics.