Patent number 8616765 is assigned to
The following quote was obtained by the news editors from the background information supplied by the inventors: "High-temperature semiconductor processing chambers are used for depositing various material layers onto a substrate surface or surfaces. One or more substrates or workpieces, such as silicon wafers, are placed on a workpiece support within the processing chamber. Both the substrate and workpiece support are heated to a desired temperature. In a typical processing step, reactant gases are passed over each heated substrate, whereby a chemical vapor deposition (CVD) reaction deposits a thin layer of the reactant material in the reactant gases on the substrate surface(s). Through subsequent processes, these layers are made into integrated circuits, and tens to thousands or even millions of integrated devices, depending on the size of the substrate and the complexity of the circuits.
"Various process parameters must be carefully controlled to ensure the high quality of the resulting deposited layers. One such critical parameter is the temperature of the substrate during each processing step. During CVD, for example, the deposition gases react at particular temperatures to deposit the thin layer on the substrate. If the temperature varies greatly across the surface of the substrate, the deposited layer could be uneven which may result in unusable areas on the surface of the finished substrate. Accordingly, it is important that the substrate temperature be stable and uniform at the desired temperature before the reactant gases are introduced into the processing chamber.
"Similarly, non-uniformity or instability of temperatures across a substrate during other thermal treatments can affect the uniformity of resulting structures on the surface of the substrate. Other processes for which temperature control can be critical include, but are not limited to, oxidation, nitridation, dopant diffusion, sputter depositions, photolithography, dry etching, plasma processes, and high temperature anneals.
"Methods and systems are known for measuring the temperature at various locations near and immediately adjacent to the substrate being processed. Typically, thermocouples are disposed at various locations near the substrate being processed, and these thermocouples are operatively connected to a controller to assist in providing a more uniform temperature across the entire surface of the substrate. For example, U.S. Pat. No. 6,121,061 issued to
"However, thermocouples employed in measuring the temperature within the high-temperature processing chamber have been found to fail due to grain slip of the wires used in the thermocouple. The thermocouple typically includes an elongated ceramic member having longitudinal bores therewithin. A pair of wires extend the length of the bores, wherein one end of the wires are fused together and positioned adjacent to the substrate for temperature measurement purposes, and the opposing ends of the wires are connected to a controller. Typically, the ends of the wire opposite the temperature measuring ends exit the bores of the ceramic member and are secured to the sheath surrounding the ceramic member in a substantially fixed manner. When the deposition processing step is taking place, the processing reactor is heated, thereby heating the ceramic member and the wires of the thermocouple. When heated, the wires expand longitudinally at a different rate than the ceramic, thereby causing longitudinal stresses in the wires. Because both ends of the wires are substantially fixed, after repeated cycles of heating and cooling the longitudinal, compression or tension stresses within the wires cause grain slip within the wires resulting in failure of the thermocouple. Accordingly, a thermocouple design that allows the wires located within the ceramic member to expand more longitudinally relative to the longitudinal expansion of the ceramic member is needed."
In addition to the background information obtained for this patent, VerticalNews journalists also obtained the inventors' summary information for this patent: "A need exists for a temperature sensing thermocouple that accommodates the different rates of thermal expansion of the support member relative to the wires received therein. In one aspect of the present invention, a thermocouple for measuring a temperature within a reaction chamber is provided. The thermocouple includes a sheath having a measuring tip and an opening. The thermocouple further includes a support member having a first distal end and an opposing a second distal end. A first wire is received within the support member, and a second wire is also received within the support member. The second wire is spaced-apart from the first wire within the support member. The thermocouple also includes a spacing member that receives the support member. The spacing member is attached to said sheath, wherein the spacing member allows the support member, the first wire, and the second wire to independently thermally expand.
"In another aspect of the present invention, a temperature control system for use in a semiconductor processing reactor is provided. The temperature control system includes at least one heating element located within the reactor. The temperature control system further includes a controller operatively connected to the heating element(s), and the controller is configured to control the heating element(s). The temperature control system also includes at least one temperature sensor located within the reactor. The temperature sensor(s) is operatively connected to the controller for providing temperature data to the controller. The temperature sensor includes a thermocouple. The thermocouple is formed of a sheath having an opening. The thermocouple also includes a support member, and a portion of the support member is disposed within the sheath. The thermocouple includes a first wire and a second wire formed of dissimilar metals. A portion of the first and second wires are received within the support member. A spacing member is operatively connected to the sheath, wherein the spacing member receives the support member and the first and second wires. The spacing member allows the support member, the first wire, and the second wire to freely thermally expand at different rates without introducing compression or tension stresses therein.
"Advantages of the present invention will become more apparent to those skilled in the art from the following description of the embodiments of the invention which have been shown and described by way of illustration. As will be realized, the invention is capable of other and different embodiments, and its details are capable of modification in various respects. Accordingly, the drawing(s) and description are to be regarded as illustrative in nature and not as restrictive."
URL and more information on this patent, see: Darabnia, Buz; Yednak, Andy; Halpin, Mike; Jacobs, Loren; Aggarwal, Ravinder. Thermocouple. U.S. Patent Number 8616765, filed
Keywords for this news article include: Electronics, Semiconductor,
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