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DE-102014203100-B4 - CERAMIC HEATING SYSTEM

DE102014203100B4DE 102014203100 B4DE102014203100 B4DE 102014203100B4DE-102014203100-B4

Abstract

A ceramic heating device (1) comprising a support base (2) made of an electrically insulating ceramic material, a heating element pattern (10) made of an electrically conductive material laid over the support base (2), and a cover layer (4) made of an electrically insulating ceramic material laid over the heating element pattern (10), wherein the ceramic heating device (1) has a through-hole (12) at each of its power supply terminals (8) for attaching connection devices, characterized in that in the vicinity of the terminals an upper surface of the cover layer (4) meets an exposed upper surface (11) of an electrically conductive layer, thereby forming a flush plane.

Inventors

  • Kano Shoji

Assignees

  • SHIN-ETSU CHEMICAL CO., LTD.

Dates

Publication Date
20260513
Application Date
20140220
Priority Date
20130313

Claims (10)

  1. A ceramic heating device (1) comprising a support base (2) made of an electrically insulating ceramic material, a heating element pattern (10) made of an electrically conductive material laid over the support base (2), and a cover layer (4) made of an electrically insulating ceramic material laid over the heating element pattern (10), wherein the ceramic heating device (1) has a through-hole (12) at each of its power supply terminals (8) for attaching connection devices, characterized in that in the vicinity of the terminals an upper surface of the cover layer (4) meets an exposed upper surface (11) of an electrically conductive layer, thereby forming a flush plane.
  2. Ceramic heating device (1) according to Claim 1 , wherein the section of the electrically conductive layer immediately adjacent to the through hole (12) is replaced by an electrically insulating ceramic body.
  3. Ceramic heating device (1) according to Claim 1 or 2 , wherein the electrically conductive layer is made of the same material as the heating element pattern (10).
  4. Ceramic heating device (1) according to Claim 1 or 2 , wherein the electrically conductive layer is either part of the heating element pattern (10) or an electrically conductive, flat medium placed around the through-hole (12).
  5. Ceramic heating device (1) according to Claim 1 or 2 , whereby the electrically conductive layer takes the form of a raised area.
  6. Ceramic heating device (1) according to Claim 5 , the elevation is caused by the fact that the support base (2) has a raised part in the form of a truncated circular cone.
  7. Ceramic heating device (1) according to Claim 5 or 6 , wherein the electrically conductive, flat means is placed on an area of the support base (2) or of the electrically conductive heating element pattern (10), wherein the electrically conductive layer is to be formed on this area.
  8. Ceramic heating device (1) according to one of the Claims 1 , 2 or 6 , wherein a corrosion-resistant, electrically conductive protective coating (7) is provided to lie above the flush plane covering an area extending from the through-hole (12) to substantially behind the exposed upper surface (11) of the electrically conductive layer.
  9. Ceramic heating device (1) according to Claim 8 , wherein the corrosion-resistant, electrically conductive protective coating (7) is made of a material selected from tungsten, tantalum, silicon, platinum, nickel, molybdenum silicide and silicon carbide.
  10. Ceramic heating device (1) according to one of the Claims 1 , 2 , 6 or 9 , wherein the support base (2) and the cover layer (4) are independently made of a material selected from aluminium oxide (Al 2 O 3 ), aluminium nitride (AlN ), boron nitride (BN ), a complex of AlN and BN , pyrolytic boron nitride (PBN ), graphite coated with pyrolytic boron nitride and quartz .

Description

Field of invention The present invention relates to a durable, ceramic heating device with high corrosion resistance, which is useful in heating wafers in processes for manufacturing semiconductor devices, optical devices, etc., in raw material heating processes, in heating for single crystal growth or for manufacturing solar cells, and in heating for melting glass or for annealing. BACKGROUND TECHNOLOGY Traditionally, an electrical resistance heating device used in a semiconductor or optical process was of a design consisting of a substrate made of a sintered ceramic, such as aluminum oxide, aluminum nitride, zirconium, boron nitride, or the like, onto which a wire or foil of a high-melting-point metal, such as molybdenum and tungsten, was wound or adhesively applied as the heating element, with an electrically insulating ceramic plate mounted to it. Alternatively, the heating element was manufactured by directly embedding it in a substrate and sintering both together in a single step. Furthermore, an improved ceramic electrical resistance heating device was developed, in which a heating element layer made of a conductive ceramic is provided over an electrically insulating ceramic substrate, and the entire system is covered with an electrically insulating ceramic cover layer, resulting in improved electrical conductivity and corrosion resistance. The ceramic support base is usually made of a sintered material obtained by sintering a raw powder after adding a sintering additive. However, the addition of a sintering additive raises concerns that impurities could cause fouling during heating and reduce corrosion resistance. Furthermore, the sintered material of the support base presents a problem regarding its resistance to thermal shock. Particularly if the dimensions are relatively large, the sintering process would be less uniform, resulting in a tendency for the sintered body to crack or develop defects. Therefore, such a body would be unsuitable for processes where rapid temperature rises or falls are unavoidable. To remedy this, a single-body electric resistance heating device was developed, made of a multi-layered ceramic consisting of a substrate made of pyrolytic boron nitride (hereinafter referred to simply as "PBN") produced by a thermochemical vapor deposition process (hereinafter also referred to as "thermo-CVD"), a heating element made of pyrolytic graphite (hereinafter referred to as "PG") applied to the surface of the substrate by thermo-CVD, and a densely laminated protective cover layer made of the same material as the substrate, which is placed over the heating element to cover the entire heating device, also produced by thermo-CVD. This type of multi-layered ceramic heating element is widely used in various fields involving rapid temperature rises or falls, particularly in continuous processes where semiconductor wafers or similar materials are treated stepwise with temperature control. It is characterized by its high chemical stability and resistance to thermal shock. Furthermore, since all constituent layers of this multi-layered ceramic heating element are manufactured using the thermo-CVD process, there are no grain boundaries, unlike in sintered ceramic heating elements produced by powder sintering. This results in a dense, non-gas-absorbing structure, thus preventing outgassing. Consequently, its popularity as a heating element that does not compromise the vacuum level during evacuation processes has increased. Furthermore, with this type of ceramic heating device, a hole must normally be formed through an end section serving as a terminal to conduct electricity to the heating element. Additionally, a portion of the heating element that forms the electrical conductor must be exposed by removing part of the electrically insulating protective cover layer covering the heating element. The common practice is to use a screw and washer at the connection points to ensure electrical conductivity. However, when this screw-and-washer fastening process is used to create electrical conductivity, tightening the screw can cause the washer to rotate slightly, which in turn can damage the edge of the insulating ceramic protective cover layer nearby and may lead to... Abnormal heating can occur due to the resulting poor electrical contact, which severely impairs the temperature distribution, and without remedy, the exposed part of the connection can wear out and begin to spark, and eventually the circuit can break at the connection section. In this regard, IP publication 1 discloses a PBN heating device in which, to prevent the aforementioned problem, a connecting pin formed with an internal thread so that it receives a screw via thread engagement, is attached to a connection point of a heating element. This means that the heating element and the connecting pin are manufactured in a single body, and this body is coated with an insulating layer. Even with this type of PBN heating element, a contact fa