KR20030097599A - Structure and fabrication of electron-focusing system and electron-emitting device employing such electron-focusing system - Google Patents

Abstract

The present invention relates to an electron-emitting device structure and a method for manufacturing the same, wherein the electron-emitting device includes an electron focusing system 37 or 37A, which system extends through the base focusing structure 38 or 38A. Into the hole 40, suitably partially passing through the base focusing structure 38 or 38A and focusing coating 39 or 39A, the focusing coating usually having a lower resistance than the base focusing structure. Formed by an angled deposit technique, in which an access conductor 106 or 106A is suitably electrically coupled to the bottom surface of the focusing coating, and the potential for controlling the focusing of electrons moving through the focusing hole. It is characterized in that it is provided to the focusing coating via the access conductor.

Description

Electromagnetic focusing system and its manufacturing method, and electron emitting device employing said electron focusing system TECHNICAL FIELD

The present invention relates to an electron-emitting device. More particularly, the present invention relates to electron-emitting device structures suitable for use in flat-panel displays of cathode ray tube ("CRT") type and methods of manufacturing the same.

Figure 1 illustrates the basic characteristics in the active area of a conventional color flat-panel CRT display operating according to the field-emission principle. The field-emitting display ("FED") of FIG. 1 consists of an electron-emitting device and a light emitting (light-emitting) device. The electron-emitting device is commonly referred to as a cathode, which contains an electron-emitting device 1 which emits electrons in a large area. The emitted electrons are directed towards the light emitting element 2 distributed on the corresponding area in the light emitting device. When the electrons collide, the light emitting element 2 emits light to produce an image on the screen of the FED.

In particular, the electron-emitting device 1 is located on the emitter electrode 3, one of which is shown in FIG. 1. The control electrode 4 intersects with the emitter electrode 3 and is electrically insulated. The set of electron-emitting elements 1 is electrically coupled with each emitter electrode 3 which intersects with the control electrode 4. For simplicity, only one electron-emitting device 1 is shown in each electrode crossing position in FIG. 1. When an appropriate voltage is applied between the control electrode 4 and the emitter electrode 3, the control electrode 4 draws electrons from the associated electron-emitting device 1. An anode (not shown) in the light emitting element directs these electrons to the light emitting element 2 separated laterally by a black matrix 5 on a transparent faceplate 6.

Under the control of the associated control electrode 4 the electrons from one electron-emitting device 1 are usually distributed in a three-dimensional cone having a maximum half angle of at least 45 ° with respect to the vertical direction of FIG. 1. For reference, FIG. 1 illustrates a 45 degree half cone at the top of one electron-emitting device 1. In the light emitting device, the unbiased electrons are distributed on the area indicated by reference numeral 7 in FIG. 1. The region 7 grows as the distance between the cathode and the anode structure increases. As illustrated in FIG. 1, unbiased electrons emitted from one electron-emitting device 1 may impinge outside the intended light emitting device 2 region.

Operating at high anode voltages for improved brightness and lifespan, FEDs require a relatively large anode-cathode space to avoid electrical arcing between the anode and the components of the cathode structure. Thus, the possibility of electrons colliding at an undesired location (e.g. light emitting element 2 adjacent to the intended light emitting element 2) is of particular interest in FEDs operating at high anode voltages.

Electron-emitting devices in the FED usually contain a focusing system that helps control the trajectory of the electrons so that most of the electrons collide only with the intended light emitting element. This focusing system generally extends above the control electrode. The lateral relationship with the electron-emitting device set of the focusing system is very important for obtaining high display performance.

2A-2C illustrate a conventional variation of the FED of FIG. 1 with the addition of a focusing system 8. The focusing system 8 forms an electronic lens that changes the electron trajectory by locally modifying the electric field between the anode and cathode structures. The amount of change in the electron orbit depends on components such as the initial orbit, the strength of the electronic lens, and the flight time inside the lens. Ideally, the characteristic of the focusing system 8 is chosen such that almost all the electrons striking collide with the intended light emitting element 2 as shown in FIG. 2A. However, electrons often collide with unwanted regions when the electron lens is under focused as in FIG. 2B or over focused as in FIG. 2C.

The ability of the electronic lens to properly focus the emitted electrons depends on the physical characteristics of the focusing system. In general, the focusing system requires the ability to maintain the desired potential. U.S. Patent 5,528,103 describes several structures of an electron focusing system capable of maintaining the potential in the FED. Unfortunately, all focusing systems in US Pat. No. 5,528,103 provide insufficient focusing capability or raise concerns about electrical short circuits with control electrodes.

It is desirable to have a focusing system that provides adequate electron focusing for the electron-emitting device without the significant risk of electrical shorting of the electrically conductive material in the focusing system with other elements such as control electrodes. In addition, the focusing system should be provided with the potential to control the electronic orbit while eliminating the problem of reliability. Also desirable is a technique for easily manufacturing such a focusing system.

1 is a simplified schematic cross-sectional side view of a portion of a conventional electron-emitting device;

2A, 2B and 2C are simplified schematic cross-sectional side views of a conventional electron-emitting device with a focusing system, each of FIGS. 2A-2C illustrating acceptable focusing, low focusing and over-focusing conditions;

3 is a side cross-sectional view of a portion of an electron-emitting device with a focusing system constructed in accordance with the present invention, seen from FIGS. 3 and 3-3;

4 is a partial plan view of the electron-emitting device of FIG. 1;

5 is a plan view of a base focusing structure, a column electrode and two emitter electrodes in the electron-emitting device of FIG. 3;

6A-6D are side cross-sectional views illustrating steps of using the techniques of the present invention to fabricate the base focusing structure of the electron-emitting device of FIGS. 3-5.

7 is a side cross-sectional view of a portion of another electron-emitting device with a focusing system constructed in accordance with the present invention;

FIG. 8 is a side cross-sectional view of a portion of an electron-emitting device with an electron focusing system of the type used in the electron-emitting device of FIG. 7, illustrating how the focusing coating of the electron focusing system is electrically contacted in accordance with the present invention. FIG. Drawing;

9-11 are plan views of three variants of the electron-emitting device of FIG. 8 (each variant using a different arrangement in contact with the focusing coating according to the invention, the cross section of FIG. Seen on page 8.);

12 is a schematic diagram of a tilted deposit system suitable for use in the present invention;

13 is a plan view of a portion of the electron-emitting device of FIGS. 8 and 9 during an inclined deposit of focusing coating according to the present invention;

14A and 14B are simplified side views illustrating steps of using the techniques of the present invention to deposit focusing coatings of the electron-emitting devices of FIGS. 8 and 9;

15 is a simplified perspective view of how some of the electron-emitting devices of FIGS. 8, 9 and 13 appear when focusing coating is formed on a base focusing structure according to the present invention;

16 is a schematic side cross-sectional view illustrating focusing control occurring in the electron-emitting device of FIGS. 8, 9, 13 and 15.

In describing the same or very similar parts or portions, the same reference numerals are used in the drawings and the detailed description of the invention.

The present invention provides an electron focusing system for electron-emitting devices suitable for use in flat-panel CRT displays, in particular FED. In the basic form of an electron-emitting device using the present electron focusing system, electrons are emitted from an electron-emitting device located in a hole in the dielectric layer. This electron-emitting device is exposed through a control hole in a control electrode overlying the dielectric layer.

The electron focusing system of the present invention includes a base focusing structure and a focusing coating. The base focusing structure has a focusing hole overlying the dielectric layer and almost overlying the electron-emitting device. Electrons emitted from the electron-emitting device travel through the focusing hole.

The focusing coating covers the base focusing structure inside the focusing hole. Suitably, this focusing coating only extends somewhat below the focusing hole, ie the focusing coating does not reach the bottom of the focusing hole. This focusing coating is usually formed of an electrically non-insulating material, ie an electrical conductor or an electrical resistive material. This focusing coating also has a lower resistance than the base focusing structure. Therefore, focusing coating generally provides most of the focusing control role of controlling the emitted electrons.

There are two advantages to configuring this focusing system so that the focusing coating only extends somewhat below the focusing hole. Firstly, the focusing coating is usually automatically separated from the control electrode. There is no short circuit between the control electrode and the focusing coating. Secondly, the present invention achieves the desired degree of focusing control by simply adjusting the amount of focusing coating extending somewhat into the focusing hole. In short, the expansion of the focusing coating towards the focusing hole makes it easy to obtain excellent focusing control while avoiding most of the short circuit problems.

The electron focusing system suitably includes an access conductor suitable for accommodating the potential for controlling electron focusing. This access conductor lies on the dielectric layer and is electrically coupled along the bottom surface thereof with the focusing coating, in particular through an access hole in the base focusing structure. Thus a focusing control potential is provided from the access conductor to the focusing coating.

The base focusing structure usually lies over a portion of the control electrode and a portion of the access conductor. Since both the control electrode and the access conductor rest on a dielectric layer, the access conductor is essentially at a level in the same electron-emitting device as the control electrode. Thus, the focusing control potential can be applied to the access conductor in much the same way as a voltage is applied to the control electrode to control the electron-emitting device. This improves stability and avoids electrical connection and routing problems that can arise when attempting to contact the focusing coating along its top surface.

The control electrode and the access conductor usually consist mainly of the same conductive material. In particular, an access conductor is formed during the formation of the control electrode. Manufacturing the focusing system in this way avoids the additional manufacturing time required to provide an access conductor in contact with the top surface of the focusing coating.

The focusing coating is usually formed according to the deposition technique inclined at an angle. That is, focusing coating is deposited on the base focusing structure at an implantation angle of less than 90 ° measured about a plane approximately parallel to the dielectric layer. The injection angle is small enough so that the focusing coating material only properly accumulates only partially into the focusing hole during the tilted deposit.

In an electron-emitting device, it is common to have a particular lateral orientation in which electron focusing control is most precisely required. For example, consider a case where the focusing hole has a larger dimension in the first side direction than in the second side direction perpendicular to the first side direction. Assume that focusing control is more important in the second direction than in the first direction.

If the focusing coating material is deposited from an inclined deposit source that is simultaneously rotating around the device at a nearly constant injection angle (less than 90 °) relative to the electron-emitting device being manufactured, the focusing hole in the first direction A larger dimension of will result in non-uniform accumulation of focusing material in the focusing hole. Attempting to set the deposit injection angle to a value that results in optimal (or near optimal) focusing control in the second direction (ie, the direction in which focusing control is most precisely desired) can have undesirable consequences. In particular, the focusing material that collides on the focusing hole simultaneously with sufficient lateral velocity in the second direction is focused with sufficient lateral velocity in the first direction even if it only proceeds partially inwardly of the focusing hole. The focusing coating material that hits the hole simultaneously may reach the bottom of the focusing hole and may short the control electrode and the focusing coating.

Such problems are solved in the present invention by making a focusing coating deposit inclined from two suitably selected opposing positions, in particular opposing positions outside the focusing hole. As used herein, deposit “position” means the initial position of a material, such as the focusing coating material, towards a target, such as the focusing hole.

The advantages of the present opposing-position deposit technique can be seen by considering what would happen if the focusing holes were defined by a pair of opposing first sidewalls each meeting a pair of opposing second sidewalls. The inclined deposit is thus performed at an opposite position behind the first sidewall such that a focused coating material accumulates to some extent in the downward direction of the first sidewall. Focusing coating material by arranging two opposingly positioned deposit positions reasonably far from the focusing hole and / or appropriately limiting the half angle at which the focusing coating material is directed from the respective position toward the focusing hole. Is not normally accumulated deeper below the second sidewall than below the first sidewall. This is true regardless of whether the first sidewall is longer or shorter than the second sidewall.

Next, the first sidewall extends in the aforementioned first direction, and the second sidewall extends in the second direction. As with the problems mentioned above, focusing control is more important in the second direction than in the first direction, but it is assumed that the focusing hole has a larger dimension in the first direction than in the second direction. Thus, the first sidewall is longer than the second sidewall.

By depositing the focusing coating material according to the opposing-positioning technique of the present invention, the distance that the focusing coating material accumulates below the second sidewall is generally the distance that accumulates below the first sidewall even if the first sidewall is longer. Not bigger than This is really necessary in this specification when focusing control is more important in the second direction. This allows the present deposition technique to provide desirable focusing control while avoiding shorting of the control electrode and focusing coating. In addition, depositing the focusing coating material from two opposing positions in the above manner is perfectly suited to the need for electrical coupling of the access conductor and the focusing coating.

While the deposit is in progress, both deposit positions may be moved from each position in a given direction, for example in a first direction. Moving the deposit position in this manner improves the uniformity of the uniform thickness of the focusing coating and the uniformity between the holes of the depth of the focusing coating extending to some extent into the focusing hole when there are several focusing holes in a given direction. It helps. In addition, movement of deposit positions in a given direction facilitates deposition of focusing coatings on large areas, thus reducing the need for significantly larger deposit systems.

The deposit technology is very flexible. Deposit parameters can be adjusted to accommodate a variety of device sizes and resolutions. In short, the present invention provides sufficient progress.

The present invention provides a matrix-arranged electron-emitting device that conducts electron focusing with focusing coating that only extends to a certain extent into the focusing hole to reduce short circuit problems. The focusing coating preferably provides a focusing control potential through (a) at the control electrode level in the electron-emitting device and (b) through an access electrical conductor externally accessible in much the same way as the control electrode to improve stability. Accept. The electron emitters of the present invention usually operate according to the field-emission principle of producing electrons that emit visible light from the corresponding light emitting fluorescent elements of the light emitting device. The combination of the electron-emitting device and the light emitting device forms a cathode ray tube of a flat-panel display such as a flat-panel television or a flat-panel video monitor for a personal computer, laptop computer or workstation.

In the following description, the term "electrical insulation" (or "dielectric") applies to materials having a resistance of 10 ¹⁰ ohm-cm or more. Thus, the term "electrically non-isolated" corresponds to a material having a resistance of 10 ¹⁰ ohm-cm or less. The electrically non-insulating material is divided into two types: (a) an electrically conductive material having a resistance of 1 ohm-cm or less and (b) an electrically resistant material having a resistance of 1 ohm-cm to 10 ¹⁰ ohm-cm. This category is determined at electric fields below 1 volt / μm. Similarly, the term "electrically non-conductive" refers to a material having at least 1 ohm-cm of resistance and includes electrical resistance and electrically insulating materials.

Examples of electrically conductive materials (or electrical conductors) are metals, metal-semiconductor compounds (metal silicides, etc.), metal semiconductor eutectics, and the like. Electrically conductive materials also include semiconductors doped at medium or high levels (n-type or p-type). Electrically resistive materials include intrinsic semiconductors and lightly doped (n-type or p-type) semiconductors. Further examples of electrical resistive materials include (a) metal-insulator mixtures such as summits (ceramic embedded metal particles), (b) graphite, amorphous carbon, and modified (e.g., doped or laser modified) diamonds. Carbon form, and the like, and (c) any silicon-carbon compound such as silicon-carbon nitrogen.

Referring to the drawings, FIG. 3 illustrates a cross section of a portion of a matrix-arranged electron-emitting device that includes a focusing system constructed in accordance with the present invention. The device of FIG. 3 operates in field-emission mode and will often be referred to herein as a field emitter. 4 shows a top view of a portion of the field emitter shown in FIG. 3. For simplicity of illustration, the vertical dimension in FIG. 4 is indicated on a scale compressed against the horizontal dimension.

The field emitters of FIGS. 3 and 4 are used in color FED divided into row and column color pixels (“pixels”). The row direction--i.e., The direction along the rows of the pillsel--is the horizontal direction in FIGS. 3 and 4. The column direction, the direction along the column of pixels perpendicular to the row direction, extends perpendicular to the plane of FIG. 3. The column direction extends perpendicular to FIG. 4. Each color pixel contains three sub-pixels of red, green and blue.

The field emitters of FIGS. 3 and 4 are produced from a thin, transparent flat baseplate 10 generally composed of glass such as Schott D263 glass having a thickness of about 1 mm. A group of opaque parallel emitter electrodes 12 lies on the baseplate 10 and extends in the row direction to form the row electrodes. Each emitter electrode 12 consists of a pair of rails 16 and a pair of rails 14 separated by an emitter hole 18 in a plan view, and has a ladder shape. The electrode 12 is usually formed of nickel or aluminum alloy to a thickness of 200 nm.

An electrical resistive layer 20 is placed on the emitter electrode 12. The resistive layer 20 provides at least 10 ⁶ ohms of resistance, generally 10 ¹⁰ ohms, between each electron-emitting device and each emitter electrode 12 located thereon, as described below. . Layer 20 usually consists of a summit with a thickness of 0.3-0.4 μm. A transparent dielectric layer 22 overlies the resistive layer 20. Dielectric layer 22 is usually composed of 0.1-0.2 탆 thick silicon oxide.

A group of laterally separated sets of electron-emitting devices 24 lie in a hole 26 that extends through the dielectric layer 22. Each set of electron-emitting devices 24 occupies an emission region lying on one crossbar 16 in each emitter electrode 12. Certain elements 24 overlying each emitter electrode 12 are electrically coupled to the electrode 12 through a resistive layer 22. The elements 24 may have various shapes. In the example of FIG. 3, element 24 is generally conical in shape and usually made of molybdenum.

A complex group of opaque control electrodes 28 that are generally parallel lies on dielectric layer 22 and extends in the column direction to form column electrodes. Each control electrode 28 controls one column of sub-pixels. Thus, three consecutive electrodes 28 control one column of pixels.

Each control electrode 28 is composed of a main control portion 30 and an adjacent gate portion 32 in which the number matches the number of emitter electrodes 12. The main controller 30 extends completely across the field emitters in the column direction. The gate portion 32 lies partly in a large control hole 34 that extends through the main portion 30. The electron-emitting device 24 is exposed through the gate hole 36 in the segment of the gate portion 32 located in the large control hole 34. Since the control holes 34 are laterally bounded by the emission area for the set of electron-emitting elements 24, each control hole 34 is sometimes called a "sweet spot." The main control unit 30 is usually made of chromium having a thickness of 0.2 μm. The gate portion 32 is usually made of chromium having a thickness of 0.04 μm.

The electron focusing system 37 is generally arranged in a lattice pattern when viewed perpendicularly to the top surface of the faceplate 10, with a dielectric layer not covered by a portion of the main control unit 30 and the control electrode 28. It is located on (22). Referring to FIG. 3, the focusing system 37 is formed of an electrically non-conductive base focusing structure 38 and a thin electrically non-insulated focusing coating 39 positioned over a portion of the base focusing structure 38. . Since the focusing coating 39 is thin and usually follows the side profile of the base focusing structure 38, only a top view of the base structure 38 of the focusing system 37 is illustrated in FIG. 4.

The non-conductive base focusing structure 38 is usually made of an electrically insulating material, but may be formed of an electrically resistive material having a sufficiently high resistance so that the control electrodes 28 are not electrically coupled to each other. The non-insulated focusing coating 39 is usually made of an electrically conductive material, in particular a metal such as 100 nm thick aluminum. Other materials suitable for the focusing coating 39 are chromium, nickel, gold, silver, and the like. The sheet resistance of the focusing coating 39 is usually 1-10 ohm / sq. In some applications, the coating 39 may be formed of an electrically resistive material. In any case, however, the resistance of the coating 39 is much smaller than the base structure 38.

There is a group of holes 40 in the base focusing structure 38, each for one set of different electron-emitting devices 24. In particular, the focusing hole 40 exposes the gate portion 32. The focusing hole 40 is concentric with and is larger than the large control hole (sweet point) 34.

In Fig. 4, the focusing hole 40 is shown to be longer in the row direction than in the column direction, with larger dimensional compression in the column (vertical) direction than in the row (horizontal) direction. In practice, the opposite is usually the case. The side dimensions of the holes 40 in the row direction are usually 50-150 μm, specifically 80-90 μm. Lateral dimensions of the holes 40 in the row direction are usually 75-300 μm. Specifically 120-140 μm, and thus much larger than the lateral dimension of the hole 40 in the row direction.

The focusing coating 39 lies on the top surface of the base focusing structure 38 and extends in the direction of the focusing hole 40, usually by 50-75%. Although the non-conductive base focusing structure 38 is in contact with the control electrode 28, the non-insulated focusing coating 39 is separated from the control electrode 28 anywhere. Looking perpendicularly from the top surface of the baseplate 10, each other set of electron-emitting devices 24 is laterally surrounded by the base structure 38 and is surrounded by the coating 39. .

The focusing system 37, mainly non-isolated focusing coating 39, consists of each of the electron-emitting devices 24 such that electrons impinge on the fluorescent material in the corresponding light-emitting device of the light-emitting device located opposite the electron-emitting device. Focuses the electrons emitted from the set. In other words, the focusing system 37 focuses the electrons emitted from the electron-emitting device 24 in each sub-pixel to strike the fluorescent material in the same sub-pixel. The efficient performance of the electron focusing function is that the coating 39 extends significantly above the element 24 and the side from each set of elements 24 to any part of the system 37, in particular any part of the coating 39. The distance needs to be well controlled.

More specifically, the pixel is a rectangle with three sub-pixels of each pixel, most of which are arranged in a straight line in the row direction. Part of the active pixel area between rows of pixels is usually allocated for the receiving edge of the spacer wall. As a result, the large control holes 34 are usually closer in the row direction than in the column direction. Therefore, better focusing control is needed in the row direction than in the column direction. Thus, an important distance that needs to be controlled to achieve good electron focusing is the row-direction distance from the side edge of the focusing system 37 to the closest edge 34C of the large control hole 34. Since edges 34C extend in the column direction, they are referred to herein as column-direction edges.

The internal pressure of the FED including the field emitters of FIGS. 3 and 4 is very low, usually around 10 ⁻⁷ −10 ⁻⁶ torr. Since the baseplate 10 is thin, the focusing system 37 also allows spacers, in particular spacer walls, to allow the FED to resist external forces such as air pressure while maintaining the desired space between the e-emitting and emitting portions of the display. Acts as a surface in contact with

The problem with distance and spacer-contact discussed above is solved by configuring the base focusing structure 38 into opposing pairs of tall primary base portions 38M and precisely arranged secondary base portions 38L. . Two sub-base focusing portions 38L of each of the opposing pairs of sub-base portions 38L are located on the corresponding one opposing surface of the large control hole 34. In the example of FIG. 3, the sub base focusing part 38L is slightly shorter than the main base focusing part 38M. A portion of the focusing coating 39 extends to some extent below the sidewall of the shorter focusing portion 38L into the focusing hole 40.

Each pair of opposing shorter base focusing portions 38L has a side aligned perpendicular to the portion 28C of the outer side longitudinal edge of the particular control electrode 28 that controls the corresponding set of electron-emitting elements 24. There is a column-direction edge 38C. A row of large control holes 34 for each corresponding set of electron-emitting elements 24 from each pair of control-electrode edges 28C and thus from a corresponding pair of focus-structure column-direction edges 38C. The distance to the -direction edge 34C is determined by the fixed photomask dimension and is well controlled. Therefore, a portion of the focusing coating 39 lying on each pair of opposing focusing portions 38L is spaced apart from the corresponding set of electron-emitting elements 24 by a well-controlled row-direction distance.

The complete planar structure of the base focusing structure 38 for the electrodes 28 and 12 can be seen in FIG. 5, which is in the same direction as FIG. 4. 5 shows two emitter electrodes 12. "42" in FIG. 5 represents a region between each pair of consecutive electrodes 12. During display assembly, the spacer wall that comes into contact with a portion of the focusing coating 39 lying on the main focusing portion 38M will generally follow some or all of the region 42. If desired, the strip of the main focusing portion 38M above the spacer-contacting area 42 may be replaced with a focusing material that extends about the same height as the shorter focusing portion 38L, thereby replacing the base focusing portion 38 with the base focusing portion 38. A groove may be provided that is covered with a focusing coating 39 for the receiving edge of the faver wall.

Base focusing structure 38 is produced from a negative-tone, electrically insulating actinic material that is usually selectively exposed to actinic radiation and developed. This actinic substance is a suitable photo-polymerizable polyimide, specifically Olin OCG7020 polyimide. The main focusing portion 38M generally extends 45-50 μm over the dielectric layer 22. The sub-focus part 38L is usually 10-20% shorter than the main part 38M.

During the display operation, an appropriate potential is applied to the focusing system 37, in particular the focusing coating 39, to control electron focusing. This focus control potential typically has a value of 25-50 volts relative to ground, causing electrons emitted from each set of electron-emitting devices 24 to focus on corresponding (directly opposite) fluorescent regions in the light emitting device.

The field emitters of FIGS. 3-5 are usually manufactured in the following manner. A blanket layer of emitter-electrode material is deposited on the baseplate 10 and patterned using a suitable photoresist mask to form a ladder shaped emitter electrode 12. As a result, the resistive layer 20 is deposited on top of the structure. The dielectric layer 22 is deposited on the resistive layer 20.

A blanket layer of electrically conductive material for the main control unit 30 is deposited on the layer 22 and patterned using an appropriate photoresist mask to form the main control unit 30 including the control apertures 34. As will be described further below, access conductors or conductors that provide a focusing control potential to the focusing coating 39 are typically created from this blanket control layer during this patterning step. The photoresist mask is created from a photomask (reticle) having a desired pattern for the main control section 30 including the column-directional edges 34C of the apertures 34.

A blanket layer of gate material is deposited on top of this structure and patterned using another photoresist mask to form gate portion 32. Gate hole 36 and dielectric hole 26 are created in gate portion 32 and dielectric layer 22, respectively, according to a charged-particle tracking procedure of the type described in US Pat. No. 5,559,389 or 5,564,959. The contents of these two patents are incorporated herein by reference. The electron-emitting device 24 is produced in the form of a cone by depositing an electrically conductive material in accordance with the deposition technique of the type described in any one of the above patents through the gate hole 36 into the dielectric hole 26.

Base focusing structure 39 is now formed as described in FIGS. 6A-6D. A primary blanket layer 38P of negative-tone, electrically insulating actinic material is provided on top of this structure. In the electron-emitting structure, there is a back actinic radiation 46 striking on the lower surface of the baseplate 10, as shown in FIG. 6B.

The baseplate 10 and dielectric layer 22 may be formed by the resistive layer 20 of the back radiation 46 while the resistive layer 20 directly transmits a sufficient percentage of the back radiation 46, specifically around 40-80%. Most of them penetrate. Electrodes 12 and 28 transmit little through radiation 46. Thus, portion 38Q of primary actinic layer 38P that is not covered by electrodes 12 and 38 is exposed to radiation 46 and the chemical structure is changed. In so doing, radiation 46 passes through emitter hole 18. Thus, a section of the primary layer 38P aligned perpendicular to the side control-electrode edge 28C is exposed to radiation 46 to define the column-wise side edge 38C of the base focusing structure 38.

The partially finished structure is now split at the top of the structure by subjecting front radiation radiation 48 through a photomask 47. See FIG. 6C. The photomask 47 has an anti-copy area 47B in the area above the focusing hole 40. Each of the protection areas 47B corresponds to an area indicated by the horizontal arrow 44 and the vertical arrow 40 of FIG. 3 or 4.

As will be described further below, the photomask 47 has a focusing coating 39 on the base focusing structure 38 to contact a corresponding access conductor generated from the blanket control layer used to create the main control 30. There is an additional anti-radiation area (not shown) over one or more respective locations extending along the thickness. The primary actinic material below this additional anti-radiation area lies on the access conductor or conductors and thus was not exposed to back radiation 46. The material of the primary layer 38P is not covered by the protection area 47B and the additional protection area is exposed to the front radiation 48 so that the chemical structure is changed.

The order in which the back and front exposures are made is generally not critical. When the actinic material is a photo-polymerizable polyimide such as Olin OCG7020 polyimide, actinic radiation during the two exposures is usually UV light which causes polymerization to the exposed polyimide.

Performing the developing operation removes the unexposed portions of the primary layer 38P to make the base focusing structure 38 and the focusing hole 40, as shown in FIG. 6D. Each hole (not shown) is simultaneously formed through the base focusing structure 38 which can bring the focusing coating 39 into contact with the corresponding access conductor. Due to the presence of the baseplate 10, the back radiation 46 does not normally pass completely through the primary layer 38P in the back exposed area. Since the sub base focusing portion 38L is exposed only to the back radiation 46, the focusing portion 38L is usually shorter than the main focusing portion 38M.

Inclined deposition of the focusing-coating material at an appropriate angle is performed to form the focusing coating 39 on the base focusing structure 38. Further formation in the tilted deposition is described below. This completes the formation of the focusing system 37 resulting in the field emitters of FIGS. 3-5.

In subsequent operations, the field emitter is sealed to the light emitting device through an outer wall. This sealing action usually results in the mounting of an outer wall and a spacer wall on the light emitting device. The composite assembly then comes into contact with the field emitter and is sealed to seal the internal display pressure to 10 ^-7 -10 ^-6 Torr. This spacer wall comes into contact with the focusing system 37 along all or part of the region 42 of FIG. 5.

The field emitters of FIGS. 3-5 are prepared according to the other procedure shown in International Application , Agent Control No. M-4386 PCT , co-filed by Spindt et al., The contents of which are incorporated herein by reference. It typically has a further lateral dimension of the size disclosed in the above international application.

7 is a cross-sectional side view of a portion of a matrix-arranged gate field emitter that includes a focusing system 37A similar to the focusing system 37. The field emitters of FIG. 7 are nearly identical to the field emitters of FIGS. 3-5 and were made in much the same way.

The focusing system 37A of FIG. 7 first passes the primary layer 38P to the front actinic radiation 48 through a photomask with a radiation-resistant strip that extends in a row direction completely crossing the intended active area of the display. Produced by treating negative-tone primary actinic layer 38P in an optional manner including exposing. Through the photomask 47, the photomask has an additional anti-radiation area above each intended location where the focusing coating extends along the thickness of the base focusing structure and contacts the corresponding access conductor. Front radiation 48 completely passes through layer 38P in this exposed area to change the chemical structure of the exposed actinic material below the row-direction anti-radiation strip and the additional anti-radiation area. .

Exposure is now effected by back radiation 46 to cause radiation 46 to partially pass through primary layer 38P in the exposed areas. The radiation 46 is made (and therefore not obscured by the electrodes 12 and 28) and only the unexposed primary actinic material between the intended positions for the focusing holes 40 in each row of focusing holes. It consists of a rectangular heat-directed primary actinic strip placed on the edge. Thus, the exposed material of the primary layer 38P is generally in a position for the heat-direction focusing edge 38C of FIGS. 3 and 4, generally in a row aligned perpendicular to the control-electrode heat-direction edge portion 28C. Has a directional edge 38E.

The primary layer 38P is now developed to remove the unexposed actinic material. The exposed remaining portion of layer 38P forms an electrically non-conductive base focusing structure 38A with focusing holes 40. The base focusing structure 38A also has access holes (not shown) in each position where the focusing coating comes into contact with the underlying access conductor. Since the back radiation 46 only partially passes through the primary layer 38P in the back-exposed areas, the heights of the overall widths of the heat-direction rectangular focus strips between the focusing holes 40 are both almost uniform and base focusing. It is lower than the height of the remaining portion of the structure 38A. Except for the fact that this point and the focusing hole 40 are more rectangular than the focusing hole 40 of FIG. 4 in plan view, the shape of the base structure 38A is generally the shape of the base structure of FIGS. 38) Same as form.

As with the back exposure of the FIGS. 6A-6D procedure, the back exposure in this optional procedure may be performed under conditions where the back radiation 46 passes completely through the primary actinic layer 38P. The height difference between (a) the column-direction rectangular focusing strip lying between the focusing holes 40 in each focusing hole row and (b) the remaining portion of the base focusing structure 38A is reduced or eliminated.

The base focusing structure 38A is provided with an electrically non-insulated focusing coat 39A similar to the focusing coat 39 to form the focusing system 37A. The focusing coating 39A is usually composed of an electrically conductive material deposited by deposition in the manner used to produce the focusing coating 39. The resulting field emitter appears as shown in FIG. "38T" and "39T" represent the top surfaces of the taller base focusing structure 38A and focusing coating 39A material at different portions of the device, respectively.

The focusing system 37 or 37A forms an electron focusing lens whose characteristics are almost defined by the lens dimensions. A basic understanding of how the lens dimensions affect electron focusing will be easy with reference to the field emitter of FIG. 7 where the top surface of the focusing coating 39A is relatively flat. In Figure 7, "80", "82", and "84" represent appropriate lens dimensions. The electronic lenses in the field emitters of FIGS. 3-5 operate in a similar manner to FIGS.

The flight time inside the electron lens is basically the time during which the emitted electrons are strongly influenced by the lens. Referring to FIG. 7, the flight time for the lens on which the focusing system 37A is formed is the distance that the focusing coating 39A extends vertically along the column-direction sidewall of the base focusing structure 38A in the focusing hole 40. 80.

The determinant of the point of electron introduction into the lens is the vertical distance from the top of the column electrode 28 to the bottom of the focusing coating 39A along the column-direction sidewall of the base focusing structure 38A in the focusing hole 40 ( 82). Although the variation of the top surface height of the column electrode 28 is represented by a large portion of the introduction-point distance 82 at the explanatory scale used in FIG. 7, the actual height variation of the top surface of the electrode 28 is introduced-. It is a small part of the point distance 82 and can be almost neglected to the extent that this in-point determinant is considered. In general, flat-panel display performance improves as the introduction-point distance 82 decreases. Thus, the distance 82 is usually made as small as possible without the risk of shorting between the electrode 28 and the focusing coating 39A.

The third determinant of the electron focusing lens is the half width of the side, across the lens, which locally affects the electrons passing through each focusing hole 40. In the field emitter of FIG. 7, the side half width for each focusing hole 40 is from the focusing coating 39A in the focusing hole 40 to the row-direction of the column electrode 28 in the hole 40. Row-direction distance 84 to the center. The side half width 84 extends from the row-direction center of the column-direction strip of the base focusing structure 38A along each focusing hole 40 to the row-direction center of the column electrode 28 in the hole 40. Should occupy a large portion of the row-direction distance 86 of < RTI ID = 0.0 > Lens aberrations that can cause unwanted electron orbits are reduced when the lateral half width 84 takes up a large portion of the row-direction distance 86.

8 shows how the field emitter of FIG. 7 is shown along the periphery of the rectangular active area 90 at the point where electrical contact is made to the focusing coating 39A to apply the focusing control potential to the focusing system 37A. Is displayed. In FIG. 8, "92" is the peripheral area where coating 39A (among other things) is in electrical contact along its lower surface to receive focus control potential.

A simplified plan view of the active region 90 and the peripheral region 92 is shown in FIG. 9. In FIG. 9, "38B" is the side boundary of the base focusing structure 38A. &Quot; 94 " represents a location where a typical spacer wall contacts the focusing coating 39A (not shown separately in FIG. 9) to separate the electron-emitting and emitting portions of the FED.

The base focusing structure 38A portion in the active region 90 consists of several row-direction strips 96R that intersect several column-direction strips 96C and define a focusing hole 40. Three row-direction strips 96R are shown in FIG. 9 and also shown in position for a spacer wall overlying the middle of the strips 96R. Although not shown in FIG. 9, normally the row- directional strip 96R is higher than the column- directional strip 96C. Each focusing hole 40 is a pair of opposing row-direction focusing sidewalls 98R of two successive row-direction strips 96R each opposing column-direction of two successive column-direction strips 96C. It is formed by a closed space that meets a pair of focusing sidewalls 98C.

Peripheral region 92 includes a column of dummy sub-pixels adjacent to each of the first and last columns of actual sub-pixels in active region 90. This dummy sub-pixel is used to test the FED. Each column of the dummy sub-pixels includes a dummy column electrode 28D formed of a group of the dummy main column portion 30D and the dummy gate portion 32D. Each dummy sub-pixel has a dummy focusing hole 40D that extends through the base focusing structure 38A. Each of the dummy focusing holes 40D is bounded in the row direction by one of the row-direction strips 96C of the base structure 38A and the wider column-direction strip 100C. In the column direction, each row-direction strip 96R borders each of the dummy focusing holes 40D. One dummy 16 of the row electrode 12 is included in each dummy sub-pixel, but there are no electron-emitting devices in the dummy sub-pixel.

The group of access holes (or bias) 102 extends through the base focusing structure 38A to the last row of dummy sub-pixels. One access hole 12 is provided for several rows of sub-pixels, typically twenty sub-pixel rows. One hole 102 is located between each pair of spacer wall locations 94.

The access hole 102 is bordered in a row direction with the column-direction strips 100C and column-direction strips 104C of the base focusing structure 38A. In the column direction, each access hole 102 is bounded by a pair of row-direction strips 96R. Thus each hole 102 is a closed space where the pair of opposing sidewalls 98R of the two row-directional strips 96R meet with the opposing column-wise sidewalls 105C of the column-directional strips 100C and 104C, respectively. Is formed. The hole 102 has a larger dimension in the row direction than the focusing hole 40. When the focusing hole 40 is 50-100 μm in the row-direction, typically 80-90 μm, the access hole 102 is 80-500 μm in the row-direction, typically 120-140 μm.

The focusing coating 39A extends deep enough into the access hole 102 to contact the access electrical conductor 106 lying on the dielectric layer 22 at the bottom of the hole 102. The access conductor 106 thus contacts the bottom surface of the coating 39A. At a minimum, the coating 39A extends completely below the left sidewall 105C of each hole 102 to contact the conductor 106. The coating 39A normally extends completely below the right sidewall 105C of each hole 102 to contact the conductor 106. However, it is not necessary that the contact of the coating 39A with the conductor 106 is made along the left sidewall 105C.

FIG. 8 shows that the focusing coating 39A contacts the entire portion of the access conductor 106 lying on the bottom of the described access hole 102. This is desirable but not required. In other words, if the coating 39A contacts the conductor 106 along the left side wall 105C, there may be a gap in the coating 39A at the bottom of each hole 102. Similarly, the coating 39A is appropriate, but not essential, to fully contact the conductor 106 fully below the row-wise sidewall 98R of each hole 102. In general, it is desirable to maximize the contact area between the conductor 106 and the coating 39A and to minimize the size of any gaps in the portion of the coating 39A inside each hole 102.

The focusing coating 39A lies on top of the base focusing structure 38A anywhere in the area inside the boundary 38B except along the bottom of the focusing hole 40 (and the dummy focusing hole 40D). have. Thus, the connection of the access conductor 106 and the coating 39A in the access hole 102 ensures that all the focusing coating portions in the focus hole 40 are electrically connected to the conductor 106.

The connection of the access conductor 106 and the focusing coating 39A through several access holes 102 separated by the spacer wall location 94 connects the spacer wall with the coating 39A at any position 94. Redundancy is provided in situations where contact is made, and thus the pressure on the spacer wall on the coating 39A causes damage to the coating 39A. If such damage occurs at location 94 below the spacer wall, the access conductor 106 remains intact and causes focus control potential to be provided to the coating 39A portions on both sides of the damaged portion. Thus, both coatings 39A receive the focused coating potential even when one or more damages in the coating 39A occur at the spacer wall location 94.

The access conductor 106 extends out of the base focusing structure boundary 38B in the column direction, as shown in FIG. 9. Suitably, both ends of the conductor 106 extend out of the boundary 38B to the location where the focus control potential is applied to the conductor 106 for transmission to the focusing coating 39A. This focusing control potential is typically provided from an electron-emitting device and a light emitting device and a voltage source located outside the sealed low pressure closed space formed by the external FED wall. Like row electrode 12 and column electrode 28 (including derby column electrode 28D), conductor 106 extends through the outer FED wall.

The access conductor 106 and the access hole 102 are formed during the steps used to fabricate the device in the active region 90. In particular, conductor 106 is produced from a portion of the blanket layer of conductive thermal material used to form primary heat portion 30 (and derby primary heat portion 30D). The hole 102 is created in the base focusing structure 38A during the formation of the focusing hole 40 (and the dummy focusing hole 40D). Thus, the formation of conductor 106 and hole 102 does not require any additional processing steps.

10 and 11 illustrate alternative plan views of a pair of active regions 90 and peripheral regions 92 in the field emitter of FIG. 7. The active regions 90 of FIGS. 10 and 11 are basically the same as those of FIG. 9. The focusing hole 39A (not shown separately in FIG. 10 or 11) is located inside the boundary 38B except that it follows the lower part of the focusing hole 40 (and the dummy focusing hole 40D). Anywhere within the included area lies back on the base focusing structure 38A.

The main difference between the field emitters of FIGS. 8 and 9 and the field emitters of FIG. 10 is that the electrically conductive material that supplies the focusing control tension to the focusing coating 39A is formed as shown in FIGS. 8 and 9. Contacting the coating 39A along the boundary 38B of FIG. In particular, the coating 39A extends under the sidewalls on both sides of the column-direction portion of the boundary 38B and is in electrical contact with the pair of access electrical conductors 108, respectively. Although not shown in FIG. 10, access conductor 108 overlies dielectric layer 22. The conductor 108 is partially below the base focusing structure 38A and extends in length in the column direction. Both ends of each conductor 108 extend beyond the boundary 38B in the column direction to the position where the focusing control potential is applied. With an access conductor 106, each conductor 108 normally receives a focus control potential from an external source through an external FED wall.

The field emitter of FIG. 11 includes several access holes 102 like the field emitters of FIGS. 8 and 9. However, instead of contacting the access conductor 106 through the hole 102, the focusing coating 39A of FIG. 11 extends through the hole 102 to provide extra access electrical conductor 110 at the bottom of the hole 102. Electrical contact with The extra access conductor 110 lies on the dielectric layer 22 below the bottom level of the base focusing structure 38A but generally does not extend out of the boundary 38B. The access conductor 110 is coated 39A along the bottom of the pair of finger-shaped access holes 112 that extend through the base structure 38A near the upper and lower right corners of the structure 38B of FIG. 11. And more connected.

Another pair of finger-shaped access holes 114 extends through the base focusing structure 38A near the upper and lower left corners of the field emitter of FIG. 11. The focusing coating 39A extends through the access hole 114 to contact a pair of access electrical conductors 116 each lying on the dielectric layer 22 below the bottom level of the base structure 38A. In contrast to the access conductor 110, the access conductor 116 extends out of the boundary 38B to the position where the focus control potential is provided to the conductor 116.

Access conductors 110 and 116 both contact the focusing coating 39A along its lower surface. Finger-shaped coating 39A characteristics of access holes 112 and 114 lie in peripheral region 92 along access hole 102, with coating 39A extending below the sidewalls of holes 112 and 114, so that the conductor ( 110, 116 increases the area in proper contact.

The connection of either access conductor 116 through the corresponding access hole 114 is usually sufficient to provide a focus control potential to the focusing coating 39A. At the coating 39A along any spacer wall location 94 as a result of the spacer wall coming into contact with the coating 39A at its location 94 or due to the continuing pressure of the spacer wall on the coating 39A. If damage occurs, the combination of access conductor 110 and access holes 102 and 112 provides redundancy to overcome the damage. In particular, the portion of the coating 39A extending in a row direction from one hole 114 to the hole 112 of the line of the hole 114 can cause the focusing control potential to move to the right side of the coating 39A. have. Thus, the connection of the coating 39A and the conductor 110 by either one of the holes 112 and the holes 102 can pass through the focused coating damage portion in the manner previously described for the field emitter of FIG. 9. Will be. Therefore, all parts of the coating 39A receive the focus control potential.

In the field emitter of FIG. 10, an access conductor 108 is created from the main thermal layer used to form the control electrode 28. The same applies to access conductors 110 and 116 of the field emitter of FIG. Access holes 112 and 114 of the field emitter of FIG. 11 are formed simultaneously with the focusing hole 40. As with the field emitters of FIGS. 8 and 9, the fabrication of a mechanism that provides a focusing control potential to the focusing coating 39A of the field emitter of FIG. 10 or FIG. 11 has already been implemented for devices in the active region 90. No further processing steps are required than required.

A vacuum metallization system suitable for performing inclined metal deposition to produce focusing coating 39 or 39A is shown in FIG. 12. “120” in FIG. 12 shows a partially finished field emitter. Field emitter 120 lies along the xy plane of the xyz coordinate system. Nearly center of the top surface of field emitter 120 is the center of the xyz coordinate system.

A focused coating metal is provided from the deposited metal source 122 located at a relatively relatively (laterally) distance away from the field emitter 120. The metal source 122 is treated herein as a point source located approximately in the xz plane. The valence of the focused coating metal evaporates from the source 122 and passes through the opening in the aperture plate 124. The major axis 126 of evaporated metal atoms lies in the xz plane and is perpendicular to the y axis.

The opening of the plate 124 limits the dispersion of evaporated metal atoms to a three-dimensional cone of half angle [alpha] about the main deposit axis 126. The value of this half angle α is selected to deposit the focused coating metal with respect to the entire top surface of the base focusing structure 38A depending on the change in the height of the top surface of the base structure 38A. The angle α is usually in the range 1-5 °. In the deposit area of the side dimension of 340 mm x 320 mm with a 10 μm height variation, α is usually 3 °.

The injection angle θ is the angle between the main deposit axis 126 and the x axis (of the field emitter 120). The value of this injection angle [theta] depends on several factors: the depth of the focusing hole 40 (ie the height of the heat-direction strip 96C between the holes 40), the focusing entering the hole 40 Nominal depth of the coating metal, minimum and maximum depth that the focused coating metal can enter the hole 40 with acceptable display performance, dimensions of the hole 40 in the row direction, possible of the hole 40 in the column direction Dimensions, depths of the holes 102 or 112 and 114 to be added, dimensions of the holes 102 or 112 and 114 in the row direction, possible dimensions of the holes 102 or 112 and 114 in the column direction, and focusing coating 39 Or nominal thickness of 39A). The injection angle θ is usually in the range 5-25 °. Each row-direction dimension of the focusing aperture 40 and the access hole 102 is a typical value of 80-90 μm and 120-140 μm, and is about 25 μm into the focusing hole 40 at a 50 μm thick focusing coating. In the field emitters of FIGS. 8 and 9 with a maximum metallization depth of θ, θ is usually 15 °.

The tilted deposition focusing metal deposit in the system of FIG. 12 is where the focusing coating 39A is formed almost all over the top surface of the base focusing structure 38A but only to some extent inside each focusing hole 40. . No part of the focusing coating metal should accumulate to a sufficient depth along the sidewall of the focusing hole 40 such that the coating 39A causes an electrical short with any of the thermal electrodes 28.

For the field emitters of FIGS. 8 and 9, the inclined deposit is such that the focusing coating 39A extends down sufficiently at least on one of the side walls of each access hole 102, suitably the left side wall ( 105C) down, in contact with the access conductor 106. A similar situation applies to the field emitter of FIG. 11, where it is in contact with the conductors 110, 116 by inclined deposition into the access holes 112, 114. The tilted deposit for the field emitter of FIG. 10 is performed in such a way that the coating 39A extends well below the right and left edges of the base focusing structure boundary 38B to contact the access conductor 108.

Following the requirements given in the previous two paragraphs, the angled deposit of the focusing coating 39A can be performed in a number of ways with the system 122/124 of FIG. For example, if the focusing hole 40 is nearly square or circular when viewed perpendicularly to the baseplate 10, the tilted deposit may cause the system 122/124 to rotate around the field emitter, Or vice versa.

The value of the injection angle θ is chosen to avoid which focused coating metal reaches the bottom of any hole 40. In this rotation technique, at least one side dimension of the access hole 102 in the field emitter of FIG. 8 or 9 or at least one side dimension of the access hole 112, 114 in the field emitter of FIG. 11 is a focused coating metal. The diameter of the focusing hole 40 must be far exceeded to reach the bottom of the holes 102 or 112 and 114 at this selected θ value. The speed of rotation with respect to the field emitter of the system 122/124 may be constant or vary.

The focusing hole 40 often has a much larger dimension in one main lateral direction than in the transverse lateral direction. If the inclined deposit proceeds according to the rotation technique at a constant θ value, a series of holes 40 having a much larger lateral dimension in one lateral direction than the transverse lateral direction may result in a focused coating metal hole 40 Accumulate to significantly different depths within In some situations, this non-uniform accumulation may cause a significant short circuit risk to the focusing coating 39 or 39A in controlling the electrode 28.

For example, the focusing hole 40 is usually 80-90 μm in the column direction and 120-140 μm in the row direction. Thus, referring to FIG. 9, the column-wise sidewall 98C of the aperture 40 is much longer than the rowwise sidewall 98R of the aperture 40. Assuming that the injection angle [theta] remains constant, performing a tilted deposit of the coating 39A while the field emitter rotates with respect to the deposit system 122/124 can cause the focused coating metal to heat up. More deeply into the hole 40 along the row-direction sidewall 98R than to the -direction sidewall 98C.

As mentioned above, the value of the in-point distance 82 of FIG. 7 needs to be small (relative to the sum of the distances 80 and 82) to obtain good electron focus. The small value of the introduction-point distance 82 corresponds to the focusing coating 39A that extends deeply into the focusing hole 40 along the column-direction sidewall 98C. If an inclined metal deposit is made according to the rotation technique at a constant θ value, an attempt to make the entry-point distance 82 small is a focusing coating 39A and column electrode along the row-direction sidewall 98R. A short circuit may occur between the 28, because the accumulation of the focused coating metal into the hole 40 is deeper along the sidewall 98R than the sidewall 98C.

Another way to perform the tilted deposition deposit is to deposit the focused coating metal at two stable positions on opposite sides of the field emitter. By appropriately selecting the positions for these two stable positions, the control electrode 28 and the focusing coating 39 or due to the focusing hole 40 having a much larger dimension in one main side direction than in the transverse side direction The possibility of a short circuit in 39A) can be avoided considerably. Generally, using this opposing-positioning technique, the deposition deposit system is arranged such that at each of the positions, the primary deposit axis is substantially perpendicular to the lateral direction having the maximum dimension of the focusing hole 40. For the general case where the dimension of the column direction is larger than the row direction of the hole 40, the main deposit axis of each of the opposing positions is almost perpendicular to the column direction.

Some azimuth fluctuation (deviation) in the angle between each main deposit axis and the lateral direction with the largest dimension of the focusing hole, ie angular fluctuations in the vertical direction, is acceptable and in some cases preferred. For example, if the row-direction strip 98R is taller than the column-direction strip 96C, the row extends down from the top of the row-direction strip 96R to the top of the column-direction strip 96C. The amount of focusing metal accumulated on the -direction sidewall 98R portion is relatively small if the main deposit axis is exactly perpendicular to the column direction.

This problem is addressed by arranging the main deposit axis to extend vertically with respect to the lateral direction with an azimuth difference of 5-25 °, specifically 10 °, from the lateral direction having the largest dimension of the focusing hole 40. These two deposit positions remain opposite each other such that their main deposit axis is nearly 180 ° azimuth difference (ie, viewed vertically).

By depositing the focusing coating 39A in such a way that it slightly deviates from this vertical, the focusing coating metal is opposed to the aforementioned position of the row-direction sidewall 98R while the deposit proceeds from one of the above positions. Accurately accumulate on one of each pair and appropriately accumulate on other portions of the sidewall portion pair while deposits proceed from other locations. The result is that the base structure 38A includes a portion of the row-direction sidewall 98R where the coating 39A extends down from the top of the row-direction strip 96R to the top of the column-direction strip 96C. It will be continuously along the top of the. The value of the azimuth angle and the depth at which the coating 39A extends into the focusing hole 40 along the column-direction sidewall 98C extends below any row-direction sidewall in any hole 40 to extend the column electrode. May be appropriately selected to avoid contact with (28).

The opposite-position tilted deposit may be performed in a continuous manner with one tilted deposit source. That is, the focusing coating material is deposited from one of the locations, then the deposit source is adjusted to another location, and more focusing coating material is deposited from the second location. Optionally, the opposite-position inclined deposits can be done with two deposit sources, with each of the sources in one of the positions at two positions, typically at the same time.

An important point in carrying out the angled deposit from the two opposing positions selected in the above manner is that even if the focusing coating material only enters the focusing hole 40 to some extent, the focusing coating material may be applied to the bottom of the access hole. To be reached, the dimensions of the holes, such as access holes 102, 112 and 114, can be easily selected. This electrically contacts the focusing coating 39 or 39A along its bottom surface to accommodate the focusing coating potential without shorting the coating 39 or 39A with the control electrode 28 at the bottom of the aperture 40. To make it possible.

FIG. 13 illustrates how the opposing-position deposit technique is applied to the field emitters of FIGS. 8 and 9 to form a focused coating 39A. 13 shows two focus hole rows and seven focus hole columns (including one dummy focus hole column). "128" and "130" in FIG. 13 indicate opposite positions of the deposit system 122/124 used to perform the tilted focused metal deposit. Locations 128 and 130 are located laterally outside of active region 90 and peripheral region 92. Location 128 lies outside of regions 90 and 92 to the right of access hole 102. Position 130 lies outside the regions 90 and 92 to the left of the first row of focusing holes 40.

The location 128 is positioned such that the primary deposit axis 126 for the deposit system 122/124 is substantially perpendicular to the column direction so that there is an azimuth fluctuation described above. Similarly, location 130 is positioned such that primary deposit axis 126 for system 122/124 is substantially perpendicular to the column direction. Because focus control is more precise in the row direction than in the column direction, the main deposit axis for positions 128 and 130 extends almost perpendicular to the lateral direction perpendicular to the lateral direction of the most precise focus control. The deposit axis 126 also lies in approximately the same vertical plane.

14A and 14B illustrate how opposing-position deposits using system 122/124 are performed on the field emitters of FIGS. 8 and 9. In Figures 14A and 14B, "132" generally represents the structure (including electron-emitting device 24 and row electrode 12) under control electrode 28 and base focusing structure 38A. In FIG. 14A, the tilted deposit starts at position 128. Atoms of the focused coating metal are deposited deposited on top of the base focusing structure 39A, as part of the focusing hole 40 (and the dummy focusing hole 40D) along the left sidewall 98C and the left sidewall ( It accumulates only to a certain extent across all of the access holes 102 along 105C) and across the portion of the access conductor 106 at the bottom of the hole 102.

The field emitter and deposit system 122/124 rotates at an azimuth angle of 180 ° to each other so that the system 122/124 is in position 130. This may be the movement of the field emitter, the movement of the system 122/124, or the movement of both the field emitter and the system 122/124.

From position 130, atoms of the focused coating metal are deposited deposited on top of the base focusing structure 38A, into a focusing hole 40 (and a dummy focusing hole 40D) along the right sidewall 98C. To some extent and to the access hole 102 along the right sidewall 105C completely and only to some extent across the portion of the access conductor 106 at the bottom of the hole 102. The result is that the focusing coating 39A only partially passes into each focusing hole 40 (or 40D) but passes both below the access hole 102 along both sides of the sidewall 105C. Thus, in any focusing hole 40, the access conductor 106 is in electrical contact with the focusing coating 39A along its lower surface within the hole 102 without shorting the control electrode 28.

The amount through which the focusing coating 39A passes along each of the focusing holes 40 along the left sidewall 98C varies to some extent from each hole 40 as compared to the right sidewall 98C. With proper choice of deposit variables, this change is usually small enough so that very few electrons reach an unintended light emitting device in the light emitting device which is low or over focused and located opposite the field emitter in the final FED. In the example shown in FIG. 14B, the focusing coating metal does not fully accumulate on the portion of the access conductor 106 exposed through the access hole 102. There is a gap 134 in the focusing coating 39A at the bottom of each hole 102. The gap 134 may be removed by appropriately adjusting the deposition conditions and / or the dimensions of the holes 102 in the row direction.

Instead of at a stationary position, deposit positions 128 and 130 can be laterally moved from their respective positions 128 and 130 in a substantially fixed lateral direction during the deposition process. This movement is generally in the column direction. For example, the position 128 can be moved from a position near the bottom row of the focusing hole 40 to a position near the top row of the hole 40 (or vice versa). The same method applies to location 130.

By appropriately limiting the half angle α of the cone, moving the positions 128 and 130 in the column direction can make the thickness of the focusing coating 39A very uniform over the top of the base focusing structure 38A. Similarly, the depth by which coating 39A extends only to some extent along focusing direction sidewall 98C to focusing hole 40 can be made uniform for each hole 40 in each row of holes 40. In addition, the moving positions 128, 130 in the column direction can make the positions 128, 130 close to the field emitters. Thus, coating 39A can be deposited on a large area field emitter without the need for a very large deposit chamber by positioning the deposit away from the field emitter.

While the opposite-position inclined deposit is in progress, the focusing coating metal is formed of the electrodes 28 and 28D and the conductors 106 using a shadow mask (not shown) in the vicinity of the focusing coating 39A. It accumulates on exposed ends and prevents them from shorting to each other. Optionally, any focused coating metal that accumulates at the exposed ends of the electrodes 28, 28D and conductor 106, on the one hand, the materials forming the electrodes 28, 28D and conductor 106, and on the other hand And may be removed by an appropriately masked etching procedure depending on the material forming the focused coating metal.

A perspective view of a portion of the focusing system 37A of the field emitter of FIGS. 8, 9 and 13 processed according to the procedure generally shown in FIGS. 14A and 14B is shown in FIG. 15. In FIG. 15, "136" shows a structure under the focusing system 37A. FIG. 15 shows that the focusing coating 39A does not extend deeper along the row-direction sidewall 98R of the hole 40 than the column-direction sidewall 98C of each focusing hole 40. .

FIG. 16 illustrates a portion of the active area 90 of the FED that includes the field emitters of FIGS. 8, 9, 13 and 15. For simplicity, each set of emitting elements 24 emitting electrons passing through each focusing hole 40 is represented by one element 24 in FIG. 16. The light emitting device lies opposite the field emitter of FIG. 16. This light emitting device includes a flat transparent faceplate 140 which is usually made of glass. Sideways separated fluorescent light emitting elements 142 lie on the inner surface of faceplate 140 in a pattern corresponding to the pattern of the set of electron-emitting elements 24 in the field emitter. The black matrix 144 surrounds the light emitting element 142 laterally. A thin light-reflecting anode layer 146 lies on the light emitting element 24 and the black matrix 144.

The focusing control state is described in FIG. 16. The focusing coating 39A is deeper along the left sidewall 98C than the right sidewall 98C in the left focusing hole 40. The opposite is true in the right focusing hole 40. The focusing coating 39A extends along its heat-direction side wall 98C by about the same distance in the center focusing hole 40. The coating 39A portion of the center hole 40 causes the electrons passing through the center hole 40 to strike the light emitting element 146 which opposes (ie, is intended) in an approximately symmetrical manner on average. Although the striking pattern is inclined left or right in the case of the left or right hole 40, the portion of the focusing coating 39A along the hole 40 controls the electron trajectory to emit light facing almost all of the emitted electrons. Bump into device 146.

Flat-panel CRT displays with electron-emitting devices made in accordance with the present invention operate in the following manner. The anode of the light emitting device is maintained at a high positive potential compared to the control electrode 28 and the emitter electrode 12. When an appropriate potential is applied between (a) a selected one of the control electrodes 28 and (b) a selected one of the emitter electrodes 12, the gate portion 32 so selected is selected from the selected electron-emitting device 24. Elect the electrons from the set and control the resulting amount of electron current. The desired level of electron emission reaches 20 volts / μm or less in a gate-cathode parallel-plate electric field normally applied at a current density of 0.1 mA / cm ² as measured by the light emitting element when the light emitting element is a high voltage phosphor Occurs when The extracted electrons pass through the anode layer and selectively strike the phosphor element to emit visible light on an outer surface of the light emitting device.

In this specification, directional terms such as "top", "bottom", "top", and "bottom" are used for reference so that the reader may easily understand how the various parts of the present invention are related to each other. In practice, the components of the present electron-emitting device may be placed in a positional relationship different from the meaning of the directional terminology used herein. The same applies to the manufacturing step mode performed in the present invention. Since directional terms are used for ease of explanation, they are included in the present invention even if the positional relationship is not strictly covered by the directional terms used herein.

While the invention has been described with reference to specific embodiments, this description is for illustrative purposes only and is not intended to limit the appended claims. For example, depositing the focusing coating 39A allows the implant angle θ to partially extend the coating 39A below the column-direction sidewall 98C and below the row-direction sidewall 98C. The furnace system 122/124 can rotate around the field emitter (or vice versa) while the deposit is in progress so that the furnace is properly adjusted to not fully expand. Injection angle as the system 122/124 rotates relative to the field emitter from the position where the primary deposit axis 126 is perpendicular to the column direction to the position where the axis 126 is parallel to the column direction, or vice versa. (θ) decreases.

The focusing holes 40 and the access holes 102, 112 and 114 may be non-rectangular in shape. The techniques used to deposit the coating 39A can be applied to the focused coating 39. Coating techniques other than deposition may be used to form coatings 39 or 39A.

Each set of electron-emitting elements 24 may consist of only one element 24 instead of several elements 24. Multiple electron-emitting devices can be placed in one hole through dielectric layer 22. The electron-emitting device 24 may be other than conical in shape. One example may be a filament, and another may be an irregularly shaped particle such as a diamond grit.

The principles of the present invention can be applied to other types of matrix-arranged flat-panel displays. Suitable flat-panel display objects include matrix-arranged plasma displays and active-matrix liquid crystal displays. Therefore, those skilled in the art will be able to make various modifications and applications without departing from the spirit and scope of the invention as defined in the appended claims.

A focusing system is provided that provides adequate electron focusing for an electron-emitting device without the significant risk of electrical shorting of the electrically conductive material in the focusing system with other elements such as control electrodes. In addition, there is provided a focusing system in which the potential for controlling the electronic trajectory can be provided while eliminating the problem of reliability in the focusing system.

Claims (61)

A system for concentrating electrons emitted by an electron-emitting device, located in a dielectric hole in a dielectric layer and exposed through a control hole in an upper control electrode: A base focusing structure overlying the dielectric layer and penetrated by a focusing hole overlying the electron-emitting device; And A focusing coating placed on the base focusing structure within the focusing hole, the focusing coating extending only to some extent in the focusing hole downwards, And said base focusing structure has opposing first sidewall pairs and opposing second sidewall pairs respectively meeting said first sidewall pairs to define said focusing holes. The method of claim 1, The focusing coating extends deeper into the focusing hole along the first sidewall than on the second sidewall on average. The method according to claim 1 or 2, The focusing coating is spaced apart from the control electrode. The method according to claim 1 or 2, And said focusing coating comprises an electrically non-insulating material. The method of claim 4, wherein And the base focusing structure comprises an electrically non-conductive material. The method according to claim 1 or 2, The focusing coating has a lower resistivity than the base focusing structure. The method of claim 1, The first sidewall extends in an approximately first lateral direction; The second sidewall extends in a second side direction approximately different from the first side direction; And Focusing control of electrons emitted from the electron-emitting device is required more precisely in the second direction than in the first direction. The method of claim 7, wherein And said focusing hole has a larger dimension in said first direction than in said second direction. The method of claim 8, And said second sidewall is higher than said first sidewall. Electron-emitting means consisting of a plurality of sets of electron-emitting devices separated laterally; A dielectric layer having a dielectric hole in which the electron-emitting device is placed; A plurality of control electrodes overlying the dielectric layer and having control holes through which the electron-emitting device is exposed; And A focusing system for focusing electrons emitted by said electron-emitting device, The focusing system lies on (a) a base focusing structure overlying the dielectric layer and penetrated by a plurality of similar focusing holes, and (b) on the base focusing structure within the focusing hole, to a certain extent below each focusing hole. Including expanding focusing coating, The respective focusing holes are respectively situated on different corresponding ones of the set of electron-emitting devices, and the base focusing structure is a plurality of first strips separated by sides extending approximately in the first lateral direction and the first direction. And a plurality of second strips separated by sides extending in a second lateral direction, wherein each successive pair of first strips intersects each successive pair of second strips with the focusing hole. Approximately qualify Focusing control of electrons emitted by the electron-emitting device is required more precisely in the first direction than in the second direction, and the focusing coating is averaged along the first strip rather than the second strip on average. Electron emitting device, characterized in that it extends deeper into the hole. The method of claim 10, And said focusing coating comprises an electrically non-insulating material. The method of claim 10, And said focusing coating is away from said control electrode and has a lower resistance than said base focusing structure. The method of claim 10, And the first strip is longer than the second strip, such that the focusing hole is longer in the first direction than in the second direction. The method of claim 10, And an anode means overlying said electron-emitting device and away from said electron-emitting device and for converging electrons emitted by said electron-emitting device. The method of claim 14, Wherein said anode means is part of a light emitting device having a plurality of light emitting elements separated on sides positioned respectively opposite to said set of electron-emitting elements so as to emit light when electrons emitted from said electron-emitting means collide; An electron emitting device. A method of manufacturing a system for focusing electrons emitted by an electron-emitting device that lies in a dielectric hole in a dielectric layer and (b) is exposed through a control hole in an upper control electrode: Forming a base focusing structure over the dielectric layer such that focusing holes extend through the base focusing structure over the electron-emitting device; And Providing a focusing coating over the base focusing structure inside the focusing hole such that focusing coating extends to some extent in the direction below the focusing hole, The providing step includes physically depositing a focusing coating material on the base focusing structure at a sufficiently small average injection angle, as measured with respect to a plane approximately parallel to the dielectric layer, such that the focusing coating material is deposited on the focusing hole. And accumulating to a certain extent inward. The method of claim 16, And the focusing coating material accumulates at least 50% deep into the focusing hole. The method of claim 16, The providing step is a manufacturing method of the electron focusing system, characterized in that performed by the deposition deposit. The method of claim 16, Opposing first sidewall pairs of the base focusing structure each meet with opposing second sidewall pairs of the base focusing structure to define the focusing hole; And The providing step directs the focusing coating material toward the focusing hole from a pair of opposing positions respectively located behind the first sidewall such that the focusing coating material is along the second sidewall rather than the first sidewall. A method of manufacturing an electron focusing system, characterized in that it accumulates more shallowly. The method of claim 19, Wherein the majority of the focusing coating material accumulates on the first sidewall rather than the second sidewall. The method of claim 16, The providing step involves directing the focusing coating material toward the focusing hole from a pair of approximately opposite positions, each having a primary deposit axis and both axes extending approximately perpendicular to the first lateral direction. A method of manufacturing an electron focusing system, characterized in that the. The method of claim 21, And said focusing hole has a larger maximum dimension in said first direction than in a second side direction perpendicular to said first direction. The method according to any one of claims 16 to 22, The focusing coating has a lower resistance than the base focusing structure. The method according to any one of claims 16 to 22, And said focusing coating comprises an electrically non-insulating material. Generating an initial structure in which a plurality of sets of electron-emitting devices that are laterally separated in an active region are placed in a dielectric hole of a dielectric layer and exposed through control holes in a plurality of control electrodes overlying the dielectric layer; Forming a base focusing structure over the dielectric layer such that a plurality of similar focusing holes respectively extend through the base focusing structure over the set of electron-emitting devices; And Providing a focusing coating over the base focusing structure within the focusing hole such that focusing coating extends to some extent in the direction below each focusing hole, The providing step includes physically depositing a focusing coating material on the base focusing structure at a sufficiently small average injection angle, as measured with respect to a plane approximately parallel to the dielectric layer, such that the focusing coating material is deposited on the focusing hole. And accumulating to a certain extent inward. The method of claim 25, And the focusing coating material accumulates at least 50% deep into the focusing hole. The method of claim 25, The focusing holes have an almost maximum lateral dimension in the first lateral direction; And The providing step directs the focusing coating material toward the focusing hole from a pair of deposit position located on opposite sides of the focusing hole as a group, each deposit being characterized by a main deposit axis, And both axes extend substantially perpendicular to the first direction. The method of claim 27, And both axes extend substantially perpendicularly to a further lateral direction that differs from the first direction by 25 °. The method of claim 27, Wherein both deposit positions are moved in a substantially specific lateral direction during the providing step. The method of claim 29, And said particular direction is substantially said first direction. The method of claim 26, The forming step includes a plurality of first strips separated into sides extending in a first side direction and a plurality of second strips separated in sides extending in a second side direction different from the first direction. Forming the base focusing structure, wherein successive pairs of the first strips each intersect each successive pair of the second strips, and in most cases define each of the focusing holes so that the focusing holes are laterally arranged in an approximately rectangular arrangement. Method of manufacturing an electron focusing system, characterized in that. The method of claim 31, wherein The providing step directs a focusing coating material from the pair of opposing positions positioned laterally outside the active area toward the focusing hole so that the focusing coating material is directed to each focusing hole along a second strip rather than a first strip of focusing hole. A method of manufacturing an electron focusing system, characterized in that it does not accumulate more deeply. The method of claim 32, Wherein each of said opposing positions is characterized by a primary deposit axis, both axes extending substantially perpendicular to said first direction. The method according to any one of claims 25 to 33, And said focusing coating comprises an electrically non-conductive material. The method according to any one of claims 25 to 33, The focusing coating has a lower resistance than the base focusing structure. A system for concentrating electrons emitted by an electron-emitting device located in (a) a dielectric hole in a dielectric layer and (b) exposed through a control hole in an upper control electrode: A base focusing structure overlying the dielectric layer and penetrated by a focusing hole overlying the electron-emitting device; And a focusing coating lying on the base focusing structure within the focusing hole and extending only to some extent below the focusing hole and extending to a substantially non-uniform depth into the focusing hole. The method of claim 36, The focusing coating is directed to the focusing hole rather than to a location where the side tangent with the focusing hole extends in the first side direction, and where the side tangent with the focusing hole extends in a second side direction different from the first direction. Electron focus system, characterized in that it extends more deeply. The method of claim 37, And the focusing hole has a larger dimension in the first direction than in the second direction. A system for concentrating electrons emitted by an electron-emitting device that lies in (a) a dielectric hole in a dielectric layer and (b) is exposed through a control hole overlying an upper control electrode: A base focusing structure overlying the dielectric layer and penetrated by a focusing hole overlying the electron-emitting device; And A focusing coating placed on the base focusing structure within the focusing hole and extending only to a certain extent below the focusing hole, And said focusing hole has a dimension in a first lateral direction greater than a dimension in a second lateral direction different from said first direction. The method of claim 39, The focusing coating extends into the focusing hole at a substantially non-uniform depth. The method according to any one of claims 37 to 40, Focusing control of the electrons emitted by the electron-emitting device is required more precisely in the second direction than in the first direction. The method according to any one of claims 37 to 40, And the directions are substantially perpendicular to each other. The method according to any one of claims 37 to 40, And the focusing hole has a height different from a side tangent with the focusing hole extending in the first direction and a height from a side tangent with the focusing hole extending in the second direction. The method according to any one of claims 37 to 40, The focusing hole is higher than at a side tangent with the focusing hole extending in the first direction than at a side tangent with the focusing hole extending in the second direction. The method according to any one of claims 37 to 40, The base focusing structure includes (a) a pair of opposing first sidewalls extending substantially in the first direction and (b) opposing extending in the second direction and respectively meeting the first sidewall to define the focusing hole. And a pair of second sidewalls. The method of claim 45, The focusing coating extends deeper into the focusing hole along the first sidewall than on the second sidewall on average. The method of claim 45, And the second sidewall has an average height different from that of the first sidewall. The method of claim 47, And said second sidewall is higher than said first sidewall. The method according to any one of claims 36 to 40, And the focusing coating is spaced apart from the control electrode. The method according to any one of claims 36 to 40, The focusing coating extends into the focusing hole to a depth of at least 50%. The method according to any one of claims 36 to 40, And the resistance of the focusing coating is lower than the resistance of the base focusing structure. The method of claim 51, wherein And the base focusing structure comprises a non-conductive material and the focusing coating comprises an electrically non-insulating material. The method according to any one of claims 36 to 40, The system can also operate to focus electrons emitted by at least one additional electron-emitting device, each of the additional electron-emitting devices being in (a) an additional dielectric hole in the dielectric layer and (b) the control electrode. Exposed through additional control apertures in the interior, wherein the focusing aperture rests on each additional electron-emitting device. The method of claim 53, wherein The control electrode includes a thin gate portion in contact with the main control portion and the main control portion and extending through the main portion, wherein each control hole extends through the gate portion at a position bounded laterally by the main hole. Electron focus system, characterized in that. The method of claim 54, wherein And said focusing hole surrounds said main hole laterally when viewed substantially perpendicular to said dielectric layer. Electron-emitting means consisting of a plurality of sets of electron-emitting devices separated laterally; A dielectric layer having a dielectric hole in which the electron-emitting device is placed; A plurality of control electrodes overlying the dielectric layer and having control holes through which the electron-emitting device is exposed; And A focusing system for focusing electrons emitted by said electron-emitting device, The focusing holes each have a larger dimension in a first side direction than in a second side direction different from the first direction, The focusing system comprises: (a) a base focusing structure overlying the dielectric layer, each of which is penetrated by a plurality of focusing holes over a corresponding other of the set of electron-emitting devices and (b) within the focusing hole And a focusing coating disposed on the base focusing structure, the focusing coating extending only to a certain degree below each focusing hole. The method of claim 56, wherein Focusing control of electrons emitted by the electron-emitting device is required more precisely in the second direction than in the first direction. The method of claim 56, wherein And the directions are substantially perpendicular to each other. The method of claim 56, wherein The base focusing structure includes a plurality of first strips separated by sides extending approximately in the first direction and a plurality of second strips separated by sides extending substantially in the second direction, each of the first strips Pairs of intersect each pair of said second strips to define each one of said focusing holes; The focusing coating extends deeper along the first strip than on the second strip on average. The method according to any one of claims 56 to 59, An electron-emitting device further comprising an anode means positioned above the electron-emitting device to collect electrons emitted by the electron-emitting device. The method of claim 60, Wherein said anode means is part of a light emitting device having a plurality of light emitting elements separated on sides lying respectively opposite the set of electron-emitting elements so as to emit light when electrons emitted by said electron-emitting means strike. An electron emitting device.