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Method and Apparatus for Inspection of Patterned Semiconductor Wafers    

A method and apparatus for inspecting a wafer surface to detect the presence of exposed conductive material...


Novel method and apparatus for inspecting a wafer surface to detect the presence thereon of exposed conductive material, particularly for determining the integrity of contact holes and vias, in semiconductor wafer manufacturing. The method comprises the steps of irradiating a spot of the wafer surface with a beam having a wavelength sufficiently shorter than the working function of the metal, such as deep UV light beam, collecting the electrons released by the irradiated wafer, generating an electrical signal that is a function of the collected electrons, and inspecting the signal to determine whether the contact holes or vias within the irradiated wafer spot are open. The apparatus comprises a vacuum chamber having therein a stage and chuck for supporting the wafer. An illumination source generates irradiating energy which is formed into a beam using appropriate optics so as to obtain the desired beam spot of the wafers surface. an electron detector collects electrons released from the wafer surface and sends a corresponding signal to a processor for processing the signal to determine whether the metal at the bottom of the hole is exposed. Optionally, the light scattered by the wafer is detected by detectors arranged around the illuminating beam.

The technology provides for a method and apparatus for inspecting HAR contact holes and vias.

The method of the technology is also advantageously applicable to the detection of non-conductive or conductive foreign matter at any location on the wafer.
It is a purpose of the technology to provide a method and an apparatus that are quickly operable and provide high throughput.
It is another purpose to provide a method and an apparatus that are compatible, and even combinable, with optical inspection methods.

The solution, provided by the technology, to the problem of the detection of the total or partial obstruction of contact holes by non-conductive matter, is based on the idea of material classification rather than conventional imaging or scattered light detection. Basically, therefore, the method of the technology comprises the step of verifying the type of material at any location on the wafer, and particularly at the bottom of the vias or contacts. This same method can also be advantageously used to detect other defects, such as metal residue defects.

Patent Summary

U.S. Patent Classes & Classifications Covered in this Patent:

Class 382: Image Analysis

This is the generic class for apparatus and corresponding methods for the automated analysis of an image or recognition of a pattern. Included herein are systems that transform an image for the purpose of (a) enhancing its visual quality prior to recognition, (b) locating and registering the image relative to a sensor or stored prototype, or reducing the amount of image data by discarding irrelevant data, and (c) measuring significant characteristics of the image.

Subclass 145: Inspection of semiconductor device or printed circuit board
Subclass 147: Inspecting printed circuit boards
Subclass 149: Fault or defect detection

Class 250: Radiant Energy

This class provides for all methods and apparatus for using, generating, controlling or detecting radiant energy, combinations including such methods or apparatus, subcombinations of same and accessories therefore not classifiable elsewhere.

Subclass 224: Article and light ray relatively moved during sensing
Subclass 574: Scattered or reflected light
Subclass 310: Electron probe type
Subclass 559.45: With defect discrimination circuitry
Subclass 397: With detector

Class 257: Active Solid-State Devices (E.G., Transistors, Solid-State Diodes)

This class provides for active solid-state electronic devices, that is, electronic devices or components that are made up primarily of solid materials, usually semiconductors, which operate by the movement of charge carriers - electrons or holes - which undergo energy level changes within the material and can modify an input voltage to achieve rectification, amplification, or switching action, and are not classified elsewhere.

Subclass E21.53: For structural parameters, e.g., thickness, line width, refractive index, temperature, warp, bond strength, defects, optical inspection, electrical measurement of structural dimensions, metallurgic measurement of diffusions (EPO)