CN1121053C

CN1121053C - Electron emitting surface layer structure of cold cathode and its preparing process

Info

Publication number: CN1121053C
Application number: CN 00117112
Authority: CN
Inventors: 许宁生; 陈建; 邓少芝
Original assignee: Sun Yat Sen University
Current assignee: Sun Yat Sen University
Priority date: 2000-05-27
Filing date: 2000-05-27
Publication date: 2003-09-10
Anticipated expiration: 2020-05-27
Also published as: CN1279496A

Abstract

The invention relates to a field electron emission surface layer structure and a manufacturing method thereof. A discontinuous surface layer of diamond particles in the shape of discrete islands is deposited on the silicon (111) surface of the substrate covered with corrosion pits to form a cold cathode electron emission surface layer structure with a low threshold electric field. Because the surface layer structure has excellent field emission characteristics, it is suitable for silicon surfaces of various areas (including large areas of more than 12 inches). Therefore, it is suitable for the application on the large-area cold cathode electron source required for making flat panel displays.

Description

Electron emitting surface layer structure of cold cathode and manufacture method thereof

Technical field

The present invention relates to a kind of field-causing electron emitting surface layer structure and manufacture method thereof.

Background technology

Films such as diamond are good field electron emission materials.Experiment and theoretical research show, the diamond thin of non-doping is extraordinary insulating material, itself not having enough free electrons can be for the field-causing electron emission, and at first enter the film conduction band at film and substrate interface with interior injection mode by conductive substrates such as metal or semiconductors by the electronics that field-causing electron is transmitted into vacuum, under the effect of film internal electric field, move to film surface subsequently, under the surface field effect, be transmitted into vacuum at last by modes such as tunnelling or accurate thermionic emission.Yet the threshold values electric field of diamond thin electronics emission at present is higher, generally in 20 megavolts/more than the rice, limited the application of cold cathode electron emitter spare greatly, thereby the operating voltage that how to reduce the threshold values electric field reduction device of electronics emission is an international popular research topic.

Summary of the invention

The purpose of this invention is to provide a kind of electron emitting surface layer structure of cold cathode and make the method for this surface texture, it is low to make the threshold field of field-causing electron emission launch threshold field than the field-causing electron of existing film.

Electron emitting surface layer structure of cold cathode of the present invention, be to deposit the diamond particles superficial layer that one deck is discrete, be discrete island shape on the substrate silicon of etch pit (111) face being covered with, the etch pit radius is at 0.5 micron to 3 microns, the edge in hole is made up of the superficial layer of stratiform, and it is the sharp shaped material of tens nanometers that there is size dimension at the edge of superficial layer.Cold cathode electronics emission relies on these discrete diamond particles islands and silicon face layer formation " microcosmic silica-based-diamond mixed structure ".

The manufacture method of electron emitting surface layer structure of cold cathode is:

1. selecting burnishing surface is the heavy doping silicon substrate of (111) face, silicon chip resistivity is 5～8.5 ohmcms, ultrasonic cleaning 15～25 minutes in acetone and absolute ethyl alcohol was respectively immersed in the hydrofluoric acid 10～20 minutes then, and is clean, air-dry with pure water or deionized water rinsing;

2. put into the corrosion of 10～50% sodium hydroxide solutions, temperature remains on 80 degrees centigrade, and is 10～60 minutes time, clean, air-dry with pure water or deionized water rinsing then;

3. carry out deposition of diamond thin films, deposition vacuum degree 1.33 * 10 ^-2～4 * 10 ^-3Handkerchief, deposition rate 40～80 nanometers/hour, sedimentation time 3 hours, depositing temperature 293～300 Kelvins, 70～120 volts of substrate biasings.

In above-mentioned manufacture method, best etching condition is: etchant solution adopts 30% sodium hydroxide solution, and temperature remains on 80 degrees centigrade, and etching time is 30 minutes.

High-energy electron diffiraction technology with transmission electron microscope records: through the surface layer structure that said method is made, the superiors are made up of many diamond particles, and these particles comprise amorphous and monocrystalline composition, and size is at 0.1 micrometer range.These particles often are grown in the edge of the uppermost surface of the silicon chip of handling through said method; The existing diamond chemical bond of these particles (sp ³Composition can reach 95%), graphite chemical bond (sp is also arranged ²Composition is not higher than 15%).The ratio of these two kinds of components can change from the substrate to the surface, and at close substrate place, the graphite composition is the highest, and the highest at surface diamond composition.Be not deposited on the film that does not have through on the above-mentioned surface-treated silicon substrate and compare, the electronic emission performance of the surface layer structure of being made by this method is good, have following characteristics: 1. the threshold values electric field of field-causing electron emission can reduce half, general never treated 20 megavolts/Mi Jiangzhi after treatment be lower than 10 megavolt/rice; 2. can be according to the electric field enhancer that farad Ao-Nuo De drought formula calculates up to about 700; 3. current density reaches 100 milliampere/square centimeters.

Fig. 1 is the structure chart of electron emitting surface layer structure of cold cathode.

Fig. 2 is a cold cathode electron emitting surface layer electron micrograph.

Fig. 3 is the graph of relation of electron emitting surface layer structure of cold cathode field emission threshold values electric field (being defined as the extra electric field when obtaining 10 microamperes of/square centimeter emissioies) and etching time.

In Fig. 1,1 is heavy doping (111) face N type or P type silicon substrate, 2 is the substrate surface etch pit, the edge in hole is made up of the superficial layer of stratiform, the sharp shaped material of the marginal existence of superficial layer size tens nanometers, 3 for being deposited on discrete, the diamond particles surface that is discrete island shape of substrate surface.

In Fig. 2, discrete shape particle shown in the photo is the diamond crystals that is grown on the corrosion silicon substrate.

In Fig. 3, ordinate is the threshold values electric field, is defined as the extra electric field when obtaining 10 microamperes of/square centimeter emissioies, and abscissa is the etching time of silicon substrate, and unit is minute.

The invention will be further described below in conjunction with embodiment.

Embodiment:

The manufacturing step of embodiment is:

1. selecting burnishing surface is the heavy doping silicon substrate of (111) face, and resistivity is 5～8.5 ohmcms, and ultrasonic cleaning 15～25 minutes in acetone and absolute ethyl alcohol respectively is clean, air-dry with pure water or deionized water rinsing;

2. add 10～50% sodium hydroxide solutions and corrode, condition sees Table 1, and is clean, air-dry with pure water or deionized water rinsing then;

3. carry out deposition of diamond thin films, deposition vacuum degree 1.33 * 10 ^-3Handkerchief, deposition rate 40～80 nanometers/hour, sedimentation time 3 hours, depositing temperature 293 Kelvins, 100 volts of substrate biasings.Concrete implementation condition and the silicon face argument structure of embodiment see Table 1.

Different implementation conditions of table 1 and silicon face argument structure

Embodiment	Silicon chip resistivity (ohmcm)	Corrosive liquid concentration (%)	Corrosion temperature (degree centigrade)	Etching time (minute)	Etch pit size (micron)	Superficial layer sharp shaped material size (nanometer)
Embodiment	Silicon chip resistivity (ohmcm)	Corrosive liquid concentration (%)	Corrosion temperature (degree centigrade)	Etching time (minute)	Etch pit size (micron)	Superficial layer sharp shaped material size (nanometer)	1	5～8.5	10	80	30	0.5～1	20～60
2	5～8.5	20	80	30	0.5～1.2	10～45	1	5～8.5	10	80	30	0.5～1	20～60
2	5～8.5	20	80	30	0.5～1.2	10～45	3	5～8.5	30	80	30	1～2	7～30
4	5～8.5	40	80	30	1.5～2	10～45	3	5～8.5	30	80	30	1～2	7～30
4	5～8.5	40	80	30	1.5～2	10～45	5	5～8.5	50	80	30	1～2	10～20
6	5～8.5	30	80	10	0.5～1	500～1000	5	5～8.5	50	80	30	1～2	10～20
6	5～8.5	30	80	10	0.5～1	500～1000	7	5～8.5	30	80	20	1～1.5	30～100
8	5～8.5	30	80	30	1～2	7～30	7	5～8.5	30	80	20	1～1.5	30～100
8	5～8.5	30	80	30	1～2	7～30	9	5～8.5	30	80	60	2～2.5	10～20
10	5～8.5	30	20	30	0.5～1	15～60	9	5～8.5	30	80	60	2～2.5	10～20
10	5～8.5	30	20	30	0.5～1	15～60	11	5～8.5	30	40	30	0.5～1.2	20～100
12	5～8.5	30	60	30	1～1.5	15～50	11	5～8.5	30	40	30	0.5～1.2	20～100
12	5～8.5	30	60	30	1～1.5	15～50	13	5～8.5	30	80	30	1～2	7～30
14	5～8.5	30	100	30	2～3	15～30	13	5～8.5	30	80	30	1～2	7～30

Claims

1. A cold cathode electron emission surface layer structure is characterized in that on the substrate silicon (111) surface covered with corrosion pits, a layer of discontinuous, diamond particle surface layer in the shape of discrete islands is deposited, and the corrosion pit radius is in From 0.5 microns to 3 microns, the edge of the pit is composed of a layered surface layer with spikes with a size of tens of nanometers on the edge of the surface layer.

2. A method for manufacturing the cold cathode electron emission surface layer structure as claimed in claim 1, characterized in that the manufacturing steps are:

a. Select a heavily doped substrate silicon wafer with a polished surface of (111) surface, the resistivity of the silicon wafer is 5 to 8.5 ohm cm, ultrasonically clean it in acetone and absolute ethanol for 15 to 25 minutes, and then immerse in hydrogen fluoride In the acid for 10-20 minutes, rinse with pure water or deionized water, and air dry;

b. Put in 10-50% sodium hydroxide solution for corrosion, keep the temperature at 80 degrees Celsius for 10-60 minutes, then rinse with pure water or deionized water, and air dry;

c. Carry out diamond film deposition, the deposition vacuum degree is 1.33×10 ^-2 ~ 4×10 ^-3 Pa, the deposition rate is 40 ~ 80 nm/hour, the deposition time is 3 hours, the deposition temperature is 293 ~ 300 Kelvin, and the substrate is biased at 70 ~120 volts.

3. a method for manufacturing cold cathode electron emission surface layer structure as claimed in claim 2, it is characterized in that optimum corrosion condition is: corrosion solution is the sodium hydroxide solution of 30% concentration, and temperature remains on 80 degrees Celsius, and corrosion The time is 30 minutes.