JP2003507863A - Cold cathode and method of manufacturing the same - Google Patents

Abstract

SUMMARY OF THE INVENTION The present invention relates to the production of highly efficient films for field effect electron emitting devices, said films being used in flat displays, electron microscopes, microwave electronics, light sources, and various other applications. Can be used to manufacture devices. More particularly, the present invention relates to a cold cathode including a substrate having a carbon film thereon. The carbon film is oriented perpendicular to the surface of the substrate and has micro-ridges and / or micro-ridges of carbon having a typical size of 0.01-1 micron and a distribution density of 0.1-10 μm ^−2. It has an irregular structure consisting of threads. The present invention also relates to a method of manufacturing a cold cathode, the method comprising generating a DC current discharge in a mixture of hydrogen and a carbon-containing additive, and depositing a carbon phase on a substrate placed on the anode. Process. This method is characterized in that the discharge is performed at a current density of 0.15 to 0.5 A / cm ² . The deposition process is performed in a mixture comprising hydrogen and ethyl alcohol or methane vapor at an overall pressure of 50-300 Torr and a substrate temperature of 600-900C. The concentration of the vapor of ethyl alcohol is 5-10% and the concentration of the vapor of methane is 15-30%. The method also relates to another method for manufacturing a cold cathode, the method including generating a microwave discharge at an input of 100-1000W. This discharge is generated under a pressure of 10 to 200 Torr in a mixture containing gaseous carbon dioxide and methane at a concentration of 0.8 to 1.2, and a carbon phase is deposited on the substrate. The method is characterized in that the deposition step is performed at a temperature of the substrate surface of between 500 and 700C.

Description

Detailed Description of the Invention

[0001] FIELD The present invention is a flat panel display, an electron microscope, microwave electronics device, a light source, and electron field emission device that can be used to manufacture the device of some other applications (field emitters For the production of highly effective films for.

Prior Art Cold emitting film cathodes having a substrate coated with a film of diamond are known ("Applications of Diamond Films and Related Materials" Third International Conference, 1995, NIST Special Publication 885, A. Feldman et al., Ed., P37, p61). To date, all attempts to create highly effective electron emitting devices based on polycrystalline diamond films are considered unsuccessful. This is due in particular to the low density of emission sites.

Closest to the invention is a low temperature emissive film cathode having a substrate coated with a carbon film ("Diamond-based field emission flat panel display" Solid State Techn., 1995, May, p71. ). The film deposited on the substrate is an amorphous carbon film.

Methods for producing cold emitting film cathodes by laser sputtering are known (“Diamond-based field emission flat panel displays”).
Solid State Techn., 1995, May, p71). The method involves depositing carbon vaporized from a graphite target on a cold substrate by high power laser radiation. The disadvantages inherent to this method are its complexity, high cost, limited scalability potential, and low density of emission sites (approximately 1000 / cm ^{2 at} 20 V / micron electric field). . This density is clearly insufficient to produce a full color display with a brightness of 256 grade.

A method is known for producing cold emitting film cathodes by plasma enhanced chemical vapor deposition, which involves DC in an electrode gap between a cathode and an anode in a stream of hydrogen.
Glow discharge, heating the substrate to the deposition temperature, injecting a carbon-containing gas into the stream, depositing a film from a mixture of hydrogen and carbon-containing gas, and discharging excess graphite phase in a hydrogen stream. Removal, including (AT Rakhimov, BV Seleznev, NVS
uetin et al. "Application of diamond film and related materials" Third International Conference Gai
thersburg, MD, USA, 1995, NISTIR 5692, Supplement NIST Special Publicati
on 885, p11s). This produces a nano-diamond film cathode. However, diamond films produced by this method have very slow growth rates and often do not have sufficient release characteristics to produce full color displays.

Methods for producing diamond cathodes are known (US Pat. No. 4,816,286).
, 1989) in a mixture of carbon dioxide and methane in a ratio of 0.8 to 1.2.
Includes microwave discharge at 100-1000 W input at ~ 100 Torr pressure and carbon phase deposition on the substrate. However, this method is very expensive and the films produced by this method have fairly non-uniform release characteristics.

[0007] SUMMARY technical problem of the present invention invention uses a flat panel display, an electron microscope, microwave electronics device, a light source, and as electron field emission device for manufacturing a device other some applications It is to obtain a low temperature emission film cathode having a high electron emission performance that can be obtained.

[0008] The purpose is to provide a low temperature emission film cathode having a substrate coated with a carbon film by deposition on it, oriented perpendicular to the surface of the substrate, 0.01
Irregularly arranged carbon micro-ridges and nano-ridges and / or micro-threads (wires: typical size of ˜1 micron and distribution density of 0.1 to 10 μm ⁻² ). It can be solved by manufacturing in the form of thread or tip) and nano-thread structures. This cathode can be manufactured by two methods.

According to a first method, a low temperature emission film cathode uses a DC glow discharge in a mixture of hydrogen and a carbon containing gas to deposit a carbon film on a substrate placed on the anode. Manufactured by The DC glow discharge is initiated at a current density of 0.15 to 0.5 A / cm ² and the deposition is carried out from a mixture of hydrogen and ethyl alcohol vapor or methane at a total pressure of 50 to 300 Torr and a substrate temperature of 600 to 900 ° C. Be implemented. At this time, the concentration of ethyl alcohol is 5 to 10%, and the concentration of methane is 15 to 30%.

According to the second method, a cold emitting film cathode is used in a mixture of carbon dioxide and methane in a ratio of 0.8 to 1.2 using a microwave discharge with an input of 5 to 50 W / cm ^3. In 2
Manufactured at a pressure of 0-100 Torr, the carbon phase deposition on the substrate is 5
It is carried out at a substrate temperature of 00 to 700 ° C.

The accompanying drawings will now be described. FIG. 1 is a photograph showing a typical image of a highly emissive film taken by a scanning electron microscope. FIG. 2 is a photograph of an image showing the distribution of the emission current from one film. FIG. 3 is a graph showing the dependence of the emission current on the strength of the electric field. FIG. 4 is a graph showing a typical Raman spectrum of the manufactured film.

As can be seen from FIG. 1, the film has a thread-like structure (a) or a strip-like structure (b) oriented perpendicular to the surface. ).

FIG. 2 shows the luminescence distribution of the fluorescent substance, which is proportional to the current density of the excitation electron beam. The sample size is 25 mm x 25 mm. It can be seen that the distribution of the emission current is extremely uniform. The density of the emissive locations was about 300,000 / cm ² , which is sufficient to produce an emissive display.

FIG. 3 shows the voltage-current characteristics of the emission current. This illustrates the dependence of the emission current on the strength of the electric field. It can be seen that the emission threshold is extremely low. The deposited material was investigated using scanning electron tunneling microscopy, X-ray diffraction, and Raman spectroscopy. FIG. 4 shows a typical Raman spectrum.

According to this investigation, it is said that the deposited material is minute graphite, and is composed of thread-like or strip-like structures randomly arranged with a distribution density of about 1 / μ ² over the entire surface of the substrate. Was shown.

Preferred Embodiments of the Method of the Invention The first method involves a DC glow discharge in a mixture of hydrogen and a carbon-containing gas and the deposition of a carbon film on a substrate placed on the anode. DC glow discharge is 0.1
Starting at a current density of 5 to 0.5 A / cm ² , deposition is initiated from a mixture of hydrogen and ethyl alcohol vapor or methane at an overall pressure of 50 to 300 Torr and 600 to
It is carried out at a substrate temperature of 900 ° C. At this time, the concentration of ethyl alcohol is 5
-10% and the concentration of methane is 15-30%.

An inert gas (eg, argon) can be dissolved in the gas mixture up to 75%. At this time, the total pressure is not changed. The method for producing a cold emitting film cathode in a DC discharge is carried out in a chamber equipped with a gas supply device for supplying and controlling a gas mixture consisting of hydrogen and a carbon-containing additive. The discharge is initiated between two electrodes connected to the power supply.
An anode is used as a support for the substrate, and a silicon plate having a thickness of 400 μm can be used as the substrate.

When the concentration of ethyl alcohol vapor is less than 5% or the concentration of methane is less than 15% and the pressure is less than 50 Torr, the rate of nucleation is decreased, and as a result, the heterogeneity of the emission characteristics is reduced. Get higher Also, the texture of the film changes. Ethyl alcohol vapor concentration is more than 10% or methane concentration is more than 30% and pressure is 30%.
If it exceeds 0 Torr, the discharge becomes unstable. If the current density exceeds 0.5 A / cm ² , the gas and the substrate are overheated, and as a result, the emission performance of the film is deteriorated.

If the current density is less than 0.15 A / cm ² , the desired activation of the gas medium cannot be obtained. When the temperature of the substrate is lower than 600 ° C. or higher than 1100 ° C., the texture of the film is significantly changed and the release characteristics are lost. The substrate temperature, determined by the discharge power, special heaters and coolers, is monitored by an optical pyrometer and its value is 6
It was measured taking into account the corresponding corrections to be in the range of 0 to 1000 ° C. The current density was 0.15 to 0.5 A / cm ² . Under such conditions, the carbon film was grown up to 10 microns / hour. Any material may be used as the substrate as long as it can withstand the deposition temperature and has high adhesion to carbon. As the substrate, any other material may be used as long as it can withstand the deposition temperature and imparts high adhesion to carbon. Prior to deposition, the substrate was treated with a suspension of diamond using conventional methods to increase the concentration of nucleation centers. In particular, ultrasonic treatment for 20 to 40 minutes can be used.

Similar film textures were obtained with 15-30% concentration of methane in the deposition process with the same parameters. A second method for producing cold emitting film cathodes is 20-100 To in a mixture of carbon dioxide and methane in a ratio of 0.8-1.2 with an input of 5-50 W / cm ^3.
Includes a microwave discharge performed at a pressure of rr and the deposition of carbon phase on the substrate.
Further in this method, the deposition is carried out at a substrate temperature of 500-700 ° C.

When the input power exceeds 50 W / cm ³ , the gas and the substrate surface are overheated, and as a result,
The release performance of the film deteriorates. If the input power is less than 5 W / cm ³ , the working medium is not sufficiently activated. If the substrate temperature is below 500 ° C or above 700 ° C,
The texture of the film changes significantly and the release properties are lost.

A second method for making a cold emission film cathode is 100% in a chamber.
Performed by microwave discharge with ~ 1000W input. A mixture of carbon dioxide and methane was used at a pressure of 20-100 Torr to effect the deposition. The ratio of carbon dioxide to methane was 0.8-1.2. The temperature of the substrate surface was 500 to 700 ° C. Under such conditions, the growth of the carbon film is 1
It was performed up to 0 micron / hour. The substrate was prepared in a manner similar to the method of making a cold emitting film cathode by DC discharge.

Industrial Application The low temperature emission cathode manufactured using the above method has a high electron emission performance, is stable in a high electric field, and has a high chemical resistance. As such, it can be used to fabricate flat panel displays, electron microscopes, microwave electronics, light sources, and devices for several other applications. The method of manufacturing this cathode has an appropriate productivity. In addition to carbon, the structure can be made from other conductive materials.

[Brief description of drawings]

FIG. 1 is a photograph showing a typical image of a highly emissive film taken by a scanning electron microscope.

[Fig. 2]   It is a photograph of an image showing the distribution of the emission current from one film.

[Figure 3]   6 is a graph showing the dependence of emission current on the strength of an electric field.

[Figure 4]   3 is a graph showing a typical Raman spectrum of a manufactured film.

─────────────────────────────────────────────────── ─── Continued front page    (81) Designated countries EP (AT, BE, CH, CY, DE, DK, ES, FI, FR, GB, GR, IE, I T, LU, MC, NL, PT, SE), EA (AM, AZ , BY, KG, KZ, MD, RU, TJ, TM), AL , AM, AT, AU, AZ, BA, BB, BG, BR, BY, CA, CH, CN, CU, CZ, DE, DK, E E, ES, FI, GB, GE, HU, IL, IS, JP , KE, KG, KP, KR, KZ, LC, LK, LR, LS, LT, LU, LV, MD, MG, MK, MN, M W, MX, NO, NZ, PL, PT, RO, RU, SD , SE, SG, SI, SK, TJ, TM, TR, TT, UA, UG, US, UZ, VN (72) Inventor Pyrevsky, Andrey Alexandr             Lovich             Russian Federation 117139 Moscow, Ul Tep             Li Stan 4-1-47 (72) Inventor Suetin, Nikolai Vladislavo             Witch             Russian Federation 144005 Electrostal             Le Renina 20 Ar-36 (72) Inventor Rakimov, Alexandre Trusnovy             Touch             Russia 119121 Moscow, Rostov             Kaya Nab 1-95 (72) Inventor Timoff, Mikhail Arkadi             Evic             Russian Federation 127484 Moscow, Ur-Dol             Goprudnaya 13-2-100

Claims (4)

[Claims] 1. A low temperature emission film cathode having a substrate coated with a carbon film, the carbon film being oriented perpendicular to the surface of the substrate.
In the form of irregular structures consisting of micro-ridges and nano-ridges and / or micro-threads or nano-threads of carbon with a typical size of 01-1 micron and a density of 0.1-10 μm ^-2 It is manufactured. 2. A method of manufacturing a cold emission film cathode comprising: DC discharge in a mixture of hydrogen and a carbon containing gas; and depositing a carbon phase on a substrate placed on the anode. The discharge is performed at a current density of 0.15-0.5 A / cm ² , and the deposition is 50-30 from a mixture of hydrogen and ethyl alcohol vapor or methane.
It is carried out at a total pressure of 0 Torr and a substrate temperature of 600 to 900 ° C., where the concentration of ethyl alcohol is 5-10% and the concentration of methane is 15-30%. 3. The method according to claim 2, wherein the deposition is carried out by adding up to 75% of an inert gas to the mixture of gases without changing the overall pressure. 4. A method of manufacturing a cold emission film cathode, comprising: 100-1
Includes a microwave discharge performed at a pressure of 20-100 Torr in a mixture of carbon dioxide and methane in a ratio of 0.8-1.2 with an input of 000 W and the deposition of a carbon phase on a substrate, The deposition is performed at a substrate temperature of 500-700 ° C.