Patent Application
20100170888
1. Field of the Invention
The present invention relates to a micro heater, a method of fabricating the same, and an environment sensor using the same. More particularly, the present invention relates to a micro heater having low power consumption and good thermal efficiency, and an environment sensor using the same.
2. Description of the Related Art
Along with the development of sensor technology, research on a micro heater used in an environment sensor such as a gas sensor has been also developed. Particularly, since low power consumption, good thermal efficiency and good thermal uniformity allowing heat to uniformly spread through an entire heater are required for a micro heater, conventional micro heaters were formed of a heat spreading structure formed in a large plate structure, or formed on a different layer from a heating part.
However, in the large plate-type heat spreading structure, large amounts of heat are lost and flexibility is decreased, and the heat spreading structure formed on a different layer from the heating part has a difficult fabrication process and decreased thermal efficiency.
For these reasons, there is a demand for a micro heater having excellent thermal efficiency and low power consumption to be suitable for an environment sensor, and an environment sensor using the same.
The present invention is directed to a micro heater, a method of fabricating the same, and an environment sensor using the same.
The present invention is also directed to a micro heater fabricated in a simple process and having good thermal efficiency and uniformity, a method of fabricating the same, and an environment sensor using the same.
One aspect of the present invention provides a micro heater including: an elastic thin film formed by sequentially depositing a first silicon oxide layer, a silicon nitride layer and a second silicon oxide layer; a heating part, a heat spreading structure and a heating part electrode, which are patterned on the elastic thin film; and an insulating layer formed on the heating part, the heat spreading structure and the heating part electrode. Here, the heat spreading structure is perpendicularly connected to the heating part at a connection portion.
Here, the heating part, the heat spreading structure and the heating part electrode may be formed of any one of poly-silicon, tungsten, aluminum, nickel and platinum. The heating part may be formed to surround the heat spreading structure. Current applied from the heating part may not flow into the heat spreading structure. The heat spreading structure may be connected to the heating part in a Wheatstone bridge type in the circuit aspect. The heat spreading structure may be formed in a multi-ringed structure, in which the rings may be connected to each other at the connection portion. The heat spreading structure may be formed in a circular disc shape. The heating part may be formed to surround the heat spreading structure in a toothed wheel-like pattern, and perpendicularly connected to the heat spreading structure at the connection portion. The pattern shape of the heating part may be transformed to increase an inner resistance thereof.
Another aspect of the present invention provides a method of fabricating a micro heater including: forming an elastic thin film by sequentially depositing a first silicon oxide layer, a silicon nitride layer and a second silicon oxide layer on a silicon substrate; patterning a heating part, a heat spreading structure and a heating part electrode, which are formed of a conductive material, on the elastic thin film; forming an insulating layer on the formed heating part, heat spreading structure and heating part electrode; and etching the silicon substrate under the elastic thin film, wherein the heat spreading structure is perpendicularly connected to the heating part at a connection portion.
According to the exemplary embodiment, in etching the silicon substrate under the elastic thin film, the silicon substrate including the insulating layer may be etched except a portion in which the heating part, the heat spreading structure and the heating part electrode are formed on the elastic thin film.
Still another aspect of the present invention provides an environment sensor including: an elastic thin film formed by sequentially depositing a silicon oxide layer, a silicon nitride layer and a silicon oxide layer; a heating part, a heat spreading structure and a heating part electrode formed on the elastic thin film; an insulating layer formed on the heating part, the heat spreading structure and the heating part electrode; and an environment sensor electrode and an environment sensing material formed on the insulating layer, wherein the heat spreading structure is perpendicularly connected to the heating part at a connection portion.
The above and other features and advantages of the present invention will become more apparent to those of ordinary skill in the art by describing in detail preferred embodiments thereof with reference to the attached drawings in which:
Hereinafter, a micro heater, a method of fabricating the same, and an environment sensor using the same will be described in detail with reference to the accompanying drawings.
Referring to
The micro heater is a heater fabricated by a semiconductor fabrication process, and the heating part 200 converts an electrical signal received from the heating part electrode 210 into thermal energy. The heat spreading structure 250 connected with the heating part 200 collects heat generated from the heating part 200 to uniformly distribute the heat. The micro heater can be fabricated in a small size, so that it can be applied to various sensors and heaters.
The silicon substrate 100 is a substrate for fabricating the micro heater of the present invention, which is the same as a silicon substrate generally used in the semiconductor process. However, since the micro heater of the present invention is fabricated in the form of a thin film, a part in which the micro heater is formed in the silicon substrate is removed through backside etching (150), after the micro heater is completely fabricated on the silicon substrate.
A lower thin film of the micro heater of the present invention is composed of the lower silicon oxide thin film 300, the silicon nitride thin film 310 and the upper silicon oxide thin film 320. The reason why the lower thin film is formed of three layers, not a single layer, is that the lower thin film of the micro heater is bent, and thus may be broken or denatured, once the micro heater is heated. To minimize the denaturation and breakage of the lower thin film, the thin layer is formed by stacking a silicon oxide layer having a compressive stress, and a silicon nitride layer having an extension stress.
The heating part electrode 210 supplies power to the micro heater according to the present invention, which is a conductive wire transmitting the power supplied from the outside to the heating part 200.
The heating part 200 is a circular conductive wire disposed along the heat spreading structure 250. Since it has a lower resistance than the heating part electrode 210, the Joule's heat is generated. The heat spreading structure 250 is in an equilibrium state of a Wheatstone-bridge with the heating part 200 in the circuit aspect, and thus no current flows into the heat spreading structure 250.
The heat spreading structure 250 collects thermal energy transmitted from the heating part 200, and is formed in a multi-ringed structure. Particularly, at a connection portion, the heat spreading structure 250 is perpendicularly connected with the heating part 200, so that they become an electrically equal Wheatstone-bridge in the circuit aspect. Therefore, current is unable to flow into the heat spreading structure 250 which thus collects only heat.
Here, the heating part 200, the heat spreading structure 250 and the heating part electrode 210 may be formed of poly-silicon, tungsten, aluminum, nickel or platinum, and also formed of any material, even a non-metal, having good thermal and electric conductivities and appropriate for such use.
The insulating layer 350 functions as a passivation layer surrounding all the heating part 200, the heat spreading structure 250 and the heating part electrode 210 to be insulated from the outside.
Referring to
The heating part electrode 210 is a conductive wire connected to the outside of the micro heater 400, and the heating part 200 is a circular conductive wire disposed along the heat spreading structure 250. The heat spreading structure 250 is formed in a multi-ringed structure, which is perpendicularly connected with the heating part 200 at a connection portion.
In this configuration, the heat spreading structure 250 collects thermal energy transmitted from the heating part 200, but no current flows into the heat spreading structure 250 from the heating part 200.
Referring to
The micro heater may be the same as that described with reference to
The silicon substrate 100 is a substrate for fabricating the micro heater of the present invention, which is the same as the silicon substrate generally used in a semiconductor process. Since the micro heater of the present invention is fabricated in the form of a thin film, the lower cave 500 is formed by etching the lower silicon oxide thin film 300, the silicon nitride thin film 310, the upper silicon oxide thin film 320 and the silicon substrate 100, excluding the micro heater 400 using microfabrication technology, which is different from that described with reference to
When the lower cave 500 is thus formed, the surroundings of the heating part 200 and the heat spreading structure 250 are opened in the actual micro heater 400 by etching the substrate, excluding the heating part electrode 210, the heating part 200 and the heat spreading structure 250, which is different from that described with reference to
Referring to
As shown in
As described above, the heat spreading structure of the present invention functions as a Wheatstone bridge in the circuit aspect, and therefore the current introduced from the outside does not flow into the heat spreading structure. The simulation result thereof is shown in
As shown in
Accordingly, the micro heater of the present invention can lose less heat than a conventional micro heater, and be significantly strong against thermal or mechanical denaturation by forming both a silicon oxide layer and a silicon nitride layer on a lower thin film.
In addition to the gas sensing device described with reference to the drawing, the micro heater can be applied to an environment sensor. It is obvious that as the environment sensor of the present invention has more micro heaters, it can be more effective.
Consequently, the present invention provides a micro heater, a method of fabricating the same, and an environment sensor using the same.
More particularly, a micro heater fabricated in a simple process and having good thermal efficiency and thermal uniformity, a method of fabricating the same, and an environment sensor using the same can be provided.
Exemplary embodiments of the present invention have been disclosed herein and, although specific terms are employed, they are used and are to be interpreted in a generic and descriptive sense only and not for purpose of limitation. Accordingly, it will be understood by those of ordinary skill in the art that various changes in form and details may be made without departing from the spirit and scope of the present invention as set forth in the following claims.
| Number | Date | Country | |
|---|---|---|---|
| 61142388 | Jan 2009 | US |
