Luxtron Corporation

Other

Charles W Schietinger

Bruce E Adams

Dmitry Vasily Bakin

Anh Ngoc Hoang

Ronald A Palfenier

Ahn N Hoang

A characteristic of a surface is measured by illuminating the surface with optical radiation over a wide angle and receiving radiation reflected from the surface over an angle that depends on the extend of the illumination angle. An emissivity measurement is made for the surface, and, alternatively, if a reflectivity measurement is made, it becomes more accurate. One application is to measure the thickness of a layer or layers, either a layer made of transparent material or a metal layer. A one or multiple wavelength technique allow very precise measurements of layer thickness. Noise from ambient radiation is minimized by modulating the radiation source at a frequency where such noise is a minimum or non-existent. The measurements may be made during processing of the surface in order to allow precise control of processing semiconductor wafers, flat panel displays, or other articles. A principal application is in situ monitoring of film thickness reduction by chemical-mechanical-polishing (CMP).

Optical techniques for measuring layer thicknesses and other surface characteristics of objects such as semiconductor wafers

The temperature of a semiconductor wafer ( ) is measured while undergoing processing in a plasma ( ) environment. At least two pyrometers ( ) receive radiation from, respectively, the semiconductor wafer and the plasma in a plasma process chamber. The first pyrometer receives radiation from either the front or rear surface of the wafer, and the second pyrometer receives radiation from the plasma. Both pyrometers may be sensitive to the same radiation wavelength. A controller ( ) receives signals from the first and second pyrometers and calculates a corrected wafer emission, which is employed in the Planck Equation to calculate the wafer temperature. Alternatively, both pyrometers are positioned beneath the wafer with the first pyrometer sensitive to a first wavelength where the wafer is substantially opaque to plasma radiation, and the second pyrometer is sensitive to a wavelength where the wafer is substantially transparent to plasma radiation.

Wafer temperature measurement method for plasma environments

A characteristic of a surface is measured by illuminating the surface with optical radiation over a wide angle and receiving radiation reflected from the surface over a wide angle. An emissivity measurement can then be made for the surface, and, alternatively, if a reflectivity measurement is made, it becomes more accurate. One application is to measure the thickness of a layer or layers, either a layer made of transparent material or a metal layer. A one or multiple wavelength technique allow very precise measurements of layer thickness. Noise from ambient radiation is minimized by modulating the radiation source at a frequency where such noise is a minimum or non-existent. The measurements may be made during processing of the surface in order to allow precise control of processing semiconductor wafers, flat panel displays, or other articles. A principal application is in situ monitoring of film thickness reduction by chemical-mechanical-polishing (CMP).

Thermal, optical, physical and chemical characteristics of a substrate (11) surface are determined with non-contact optical techniques that include illuminating (23) the surface with radiation having a ripple intensity characteristic (51), and then measuring the combined intensities (53) of that radiation after modification by the substrate surface and radiation emitted from the surface. Precise determinations of emissivity, reflectivity, temperature, changing surface composition, the existence of any layer formed on the surface and its thickness are all possible from this measurement. They may be made in situ and substantially in real time, thus allowing the measurement to control (39, 41) various processes of treating a substrate surface. This has significant applicability to semiconductor wafer processing and metal processing.

Non-contact optical techniques for measuring surface conditions

A non-contact pyrometric technique is provided for measuring the temperature and/or emissivity of an object that is being heated by electromagnetic radiation within the optical range. The measurement is made at short wavelengths for the best results. The measurement may be made at wavelengths within those of the heating optical radiation, and the resulting potential error from detecting heating radiation reflected from the object is avoided by one of two specific techniques. A first technique utilizes a mirror positioned between the heating lamps and the object, the mirror reflecting a narrow wavelength band of radiation in which the optical pyrometer detector operates. The second technique is to independently measure the a.c. ripple of the heating lamp radiation and subtract the background optical noise from the detected object signal in order to determine temperature and emissivity of the object. Both of these techniques can be combined, if desired.

Non-contact techniques for measuring temperature of radiation-heated

The thickness of a thin film on a substrate surface is determined by measuring its emissivity and temperature with a non-contact optical technique and then calculating the film thickness from these measurements. The thickness of the film can be determined by this technique in situ, while it is being formed and substantially in real time, thus allowing the measurement to control the film forming process. This has application to controlling the formation of dielectric and other material layers on a semiconductor substrate in the course of manufacturing electornic integrate circuits, including automatically terminating the process at its endpoint when the layer has reached a desired thickness.

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Portland, OR, United States of America

Charles W Schietinger