Semiconductor device manufacturing: process – Electron emitter manufacture
Reexamination Certificate
1999-12-14
2001-07-31
Crane, Sara (Department: 2811)
Semiconductor device manufacturing: process
Electron emitter manufacture
C438S238000, C438S931000
Reexamination Certificate
active
06268229
ABSTRACT:
BACKGROUND OF THE INVENTION
The present application relates to integrated circuit devices and methods which employ amorphous silicon carbide resistor materials, including field emission devices, as well as methods for fabricating and using the foregoing.
The development of high density integrated circuit technology has been limited by the inability to provide suitable materials for integrated circuit resistor elements. Such materials typically must possess the ability to withstand intense electric fields without suffering breakdown, since their dimensions are so small. Moreover, the small size of these components requires high, tunable resistivity in order to achieve useful component resistances in many applications.
One promising application for integrated circuit technology is in the fabrication of flat panel displays that employ cold cathode field emission. Efforts to develop such devices have sought to utilize a large number of microtip emitters in each display pixel to achieve useful field emission current levels. But shorts, which can occur between some of the emitters and the gate can make the device inoperable. Variations in emitter geometries and in surface chemical properties can result in non-uniform field emission and varying brightness across the display. It has been proposed to insert a resistor layer between the microtip emitters and their current source (normally a cathode electrode) to overcome these problems.
A key to the successful development of such flat panel field emission displays, therefore, is the development of a resistor material having sufficiently high resistivity and capable of withstanding the intense electric fields which arise when breakdown occurs at the microtip emitters.
High speed, high density static RAM applications require the fabrication of integrated circuit resistor elements of very small dimensions, and consequently, require materials having high resistivity and the capability to withstand intense electrical fields. Similar requirements exist in other integrated circuit applications in which resistor elements are useful.
For a material to be suitable for this application, it should be possible to form electrical contacts with the material readily and the resistor material must be compatible with other materials used in fabricating the device. For example, the material should not react with other materials in the device.
The cost of device fabrication is another very important consideration. Materials which require high fabrication temperatures typically are undesirable since this limits the choice of compatible materials which can withstand such high temperatures without an undesirable change in their properties. In the case of flat panel field emission displays, low temperature processing is desirable to permit the use of less expensive substrates. At the same time, the resistor material should form a highly uniform film when it is deposited at such low temperatures. Another important consideration is the ability to selectively etch the materials to achieve the desired structure.
Yet another important consideration is that a suitable resistor material should have characteristics which either do not change after deposition as a result of further cathode processing, or else change in a limited and predictable way. Likewise, over time as the device is used repeatedly, the characteristics of the resistor material should either remain the same or change in a limited and predictable fashion.
While silicon has been proposed for use as such a resistor material, it is impractical to fabricate silicon resistor layers possessing sufficiently high resistivity for many applications. To achieve high resistivity in silicon, it is necessary to deposit this material in a very pure form which substantially increases fabrication cost.
It has been proposed to use cermet materials for use as resistor layers in flat panel field emission devices. However, it has proven very difficult to provide cermet resistor layers having sufficiently high resistance, as well as to select a desired resistance of such materials through doping. The resistivity of cermet also changes with thermal cycling and it is difficult to deposit and etch this material uniformly. Moreover, cermet has a grain structure that leads to uneven contact with the microtip emitters of the device and consequently, affects the resistances between the emitters and cathode electrode uncontrollably. This leads to uneven resistance values which result in non-uniform emission among the emitters.
Amorphous materials lacking such a grain structure do not share this drawback, and they are readily fabricated and processed. However, amorphous materials are thought to be unstable, tending to change their properties substantially over time or as a result of further processing after layer formation. Amorphous silicon with hydrogen added can have a suitably high resistivity, but hydrogen gas evolution can cause problems in amorphous materials processed at higher temperatures since it results in changes in material properties, and in some cases can form gas bubbles which disrupt the material.
OBJECTS AND SUMMARY OF THE INVENTION
It is an object of the present invention to provide integrated circuit devices incorporating resistor materials having high resistivity and capable of withstanding high electric fields, as well as methods for fabricating and using the same.
It is a further object of the present invention to provide such devices and methods of fabricating the same which are inexpensive to implement.
It is a further object of the present invention to provide such devices which operate over long periods of time and despite repeated use, without substantial degradation in their operating characteristics.
It is yet another object of the present invention to provide flat panel field emission devices which employ resistor layers to achieve uniform field emission across the display and which are operable without substantial risk of destruction due to breakdown.
In accordance with one aspect of the present invention, a field emission device is provided having a resistor element which comprises amorphous Si
x
C
1-x
wherein 0<x<1, and wherein the si
x
C
1-x
incorporates at least one impurity selected from the group consisting of hydrogen, halogens, nitrogen, oxygen, sulphur, selenium, transition metals, boron, aluminum, phosphorus, gallium, arsenic, lithium, beryllium, sodium and magnesium.
In accordance with another aspect of the present invention, a method of making a field emission device is provided comprising forming a resistor element on a substrate, the resistor element comprising amorphous Si
x
C
1-x
wherein 0<x<1 and the amorphous Si
x
C
1-x
incorporates at least one impurity selected from the group consisting of hydrogen, halogens, nitrogen, oxygen, sulphur, selenium, transition metals, boron, aluminum, phosphorus, gallium, arsenic, lithium, beryllium, sodium and magnesium, and forming at least one electron emitting structure on the substrate coupled with the resistor element.
In accordance with a further aspect of the present invention, a method of emitting electrons from a field emission device is provided comprising: providing a field emission device mounted on a substrate wherein the field emission device comprises at least one electron emitting structure and a resistor element coupled with the emitting structure; and applying an electric field to the emitting structure such that electric current is conducted through the resistor element to the emitting structure and electrons are emitted therefrom, wherein the resistor element comprises amorphous Si
x
C
1-x
wherein 0<x<1 and the Si
x
C
1-x
incorporates at least one impurity selected from the group consisting of hydrogen, halogens, nitrogen, oxygen, sulphur, selenium, transition metals, boron, aluminum, phosphorus, gallium, arsenic, lithium, beryllium, sodium and magnesium.
In accordance with yet another aspect of the present invention, an integrated circuit is provided comprising a substrate, a resistor layer comprising am
Beetz Charles P.
Besser Ronald S.
Brandes George R.
Ramani Swayambu V.
Xu Xueping
Advanced Technology & Materials Inc.
Crane Sara
Hultquist Steven J.
Zitzmann Oliver A.
LandOfFree
Integrated circuit devices and methods employing amorphous... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Integrated circuit devices and methods employing amorphous..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Integrated circuit devices and methods employing amorphous... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2447230