WO2012151789A1

WO2012151789A1 - Method and apparatus for implanting laser-induced plasma into substrate

Info

Publication number: WO2012151789A1
Application number: PCT/CN2011/077731
Authority: WO
Inventors: 任旭东; 李应红; 皇甫喁卓; 汪诚; 阮亮; 何卫峰; 周鑫; 楚维; 张永康; 戴峰泽; 张田
Original assignee: 江苏大学; 中国人民解放军空军工程大学
Priority date: 2011-05-11
Filing date: 2011-07-28
Publication date: 2012-11-15
Also published as: CN102208321B; CN102208321A

Abstract

The present invention relates to the technical field of ion implantation apparatus and ion implantation material processing. A method and apparatus for implanting laser-induced plasma into a workpiece. A high-power short-pulse intense laser beam stimulated by a laser impacts a metal foil (13). The metal foil instantaneously vaporizes and ionizes by absorbing the energy of the high-power short-pulse laser beam, thereby generating a high-temperature plasma. The plasma is constituted by metal ions (11), electrons (12), and uncharged atoms. The plasma expands and explodes by absorbing subsequent laser energies. During the plasma explosion process, a repulsive force between the electrons (12) and a negative potential-connecting workpiece (6) makes the electrons (6) to move away from the workpiece (6). A positively charged plate neutralizes some of the electrons (12). An attractive force between metal cations (11) and the negative potential workpiece (6) makes the metal ions (11) to move towards the workpiece (6). By superimposition of the shock wave effect formed by the expansion and explosion of the plasma and the attraction effect of electric fields, the metal ions are blasted at a great speed onto a surface of the workpiece (6), thus completing the implantation of metal ions.

Description

Method and device for injecting laser induced plasma into substrate

Technical field

The invention relates to the technical field of ion implantation device and ion implantation material processing, and particularly relates to a method and a device for injecting metal ions into a surface layer of a substrate by separating high energy pulse laser induced plasma.

Background technique

Injecting ions of other elements into the surface layer of the material can cause changes in the properties of the substrate. For example, injecting Mo and W ions into the steel can enhance the impact resistance characteristics; injecting N ions into the aluminum alloy can increase the hardness; injecting N into the titanium alloy, C ion can improve corrosion resistance and fatigue resistance; injecting Al ions into steel sections to improve heat resistance, abrasion resistance and corrosion resistance, this technology is applicable to semiconductors, metal materials, ceramic materials, polymer materials, optical materials, etc. Surface modification. It has been widely used in the industrial field. Various countries have produced various ion implanters, 20N ion implanters produced by American Ion Implant Science, and Danke 1090 ion implanters produced by Danish Physics. Metal vapor vacuum arc (MEVVA) ion implantation is an advanced high-current, large-area line-of-sight processing technology. This metal ion source ion implanter has reached a practical stage. At present, the largest metal ion source ion implanter ion beam is extracted. The diameter of the device has reached 500mm and the beam current is up to 10A, but the metal ion source ion implantation is still a line of sight process. In order to overcome the line-of-sight process of the ion beam implanter, J., Department of Nuclear Engineering, University of Wisconsin, USA, 1987 R. Conrad proposed the "plasma source ion implantation" technology and obtained the US patent in 1988. Commonly used plasma generating methods include a DC filament heating and discharging power source, a microwave excitation source, an electron cyclotron resonance excitation source, an RF excitation source, and a capacitive coupling excitation source, each having advantages and disadvantages. In general, the ion implantation process always has the problem of shallow injection layers. For the first time, the present invention uses a laser-induced plasma as an ion source to produce a high density plasma without contamination.

technical problem

The method of ion implantation referred to in the present invention can overcome the above disadvantages by using laser induced plasma and radiant heating of the workpiece. The ion source is clean, the reaction speed is fast, the depth of the injection layer is large, and the hardness is high.

Technical solution

The main process of the invention for ion implantation is that a high-energy short-pulse intense laser strikes a metal foil, and the metal foil absorbs high-energy short-pulse laser energy to instantaneously vaporize and ionize, and generates a high-temperature plasma, which is composed of metal ions, electrons, and uncharged atoms. Composition, plasma absorption followed by laser energy expansion and explosion. During the plasma explosion, the repulsive force between the electron and the negative potential workpiece causes the electron to move away from the workpiece, part of the electron is absorbed by the positive charge plate, and the other part is left in the next reaction process. The phase suction between the positive-valence metal ions and the negative-potential workpiece causes the metal ions to move toward the workpiece, hitting the surface of the workpiece at a great speed, and completing the metal ion implantation. The movement speed of metal ions is superimposed and synthesized in two parts. One is the shock wave formed by the plasma expansion and explosion, and the other is the attraction of the electric field. Heating can increase the depth of the ion strengthening layer, increase the hardness of the injection layer, and improve the quality and efficiency of ion implantation.

The apparatus of the present invention includes three systems: a plasma generation system, a vacuum reaction chamber system, and a workpiece system.

The plasma generation system includes a high power neodymium glass laser that excites a high energy short pulse laser, a 45° full mirror, a focusing lens, and a laser ablation material attached to the inner side of the upper glass plate.

The vacuum reaction chamber system comprises: a cylindrical sealed cavity formed of high pressure resistant glass, the upper glass cover is circular, the diameter of which is slightly larger than the diameter of the cavity, and the upper glass cover and the cavity are sealed and connected by a sealing ring, The glass cover can be opened and sealed to the cavity under working conditions. There is an air inlet hole at a position above one side of the side wall of the cavity, and an air outlet hole at a lower position of the other side of the opposite side, the air inlet hole is used for driving a working gas, for example, a nitrogen source is input when nitrogen ion is injected, and the air pump is used. The chamber is evacuated to a predetermined degree of vacuum via a bleed hole. Four arc-shaped charge receiving plates are mounted on the inner wall of the cavity, which are located on two perpendicular diameters of the cavity, and the opposite two blocks are arranged one above the other, which is advantageous for the electrons and negative ions to be sufficiently absorbed. The charge sensor is mounted on a charge receiving plate and a positive voltage source is coupled to the charge receiving plate for inputting and controlling the amount of positive charge on the positive charge receiving plate. A sensor that monitors the pressure inside the chamber is located at the bottom of the chamber and is connected to an external pressure gauge. The connecting wires inside and outside the cavity pass through the same position of the cavity and are sealed. There are two elliptical cylindrical legs under the cavity.

The workpiece system includes: the workpiece is positioned and clamped on the inverted trapezoidal workbench, and the worktable is equipped with a liftable table support. The length of the support is controlled to control the up and down rotation angle of the workbench to meet the requirements of the bevel processing. The shape of the bracket is cylindrical, and the cavity is sealed with a large elastic sealing ring to ensure that the sealing ring is still in a sealed working state after the bracket is moved. The radiant heater is located in a recessed portion below the workbench, the heater adopts a radiant heating method, the heating wire is a molybdenum wire, and the molybdenum wire is uniformly arranged in parallel in the same plane, and the cylindrical portion of the radiant heater and the lower end of the cavity are sealed by a sealing ring. A temperature sensor for measuring the temperature of the workpiece is placed on the workpiece and connected to the temperature display meter outside the chamber to monitor the operating temperature of the workpiece. A pulsed negative high voltage source is connected to the workpiece to apply a negative potential to the workpiece. All wires are sealed at the same location as the wires of the vacuum reaction chamber. The computer controls the parameter setting of the laser, records the change in charge on the positive charge plate, and controls the lift of the table support.

The specific steps of the method of the present invention are:

1. Use a sandpaper to remove the oxide layer on the surface of the workpiece and polish it, then remove it with an emulsifier and absolute ethanol.

2. Raise the table support to a certain height, fix the pre-processed workpiece to the workbench from above the cavity, attach a temperature sensor to the surface of the workpiece, connect the pulsed negative high-voltage source connector to the side, and then lower the workbench to work. Height, adjust the position of the radiant heater, and then seal the contact part between the heater, the table bracket and the high pressure resistant vacuum chamber;

3. Put a layer of metal foil on the upper glass plate, then cover the glass plate on the cavity, the metal foil is downward, sealed by the sealing plate, and then fixed by force;

4. Seal the air inlet hole, pump the gas from the air suction hole with a vacuum pump, observe the pressure gauge, and make the internal pressure reach 10-4~10-1Pa;

5. Turn on the radiant heater power supply to heat the workpiece, the temperature of the workpiece is controlled by the temperature sensor at 600~800 °C; the positive power supply is turned on on the positive charge plate, the positive potential is 3~5kv, the pulse on the workpiece is connected to the negative high voltage source, and the negative potential is 40. ~60kv, pulse width 50~100μs, pulse repetition frequency 50Hz;

6. Turn on the laser, set the laser energy, pulse width, spot diameter and other parameters by the computer. The laser strikes the metal foil 3 times. After the reaction is completed, all the power supplies are turned off and the workpiece is removed.

Beneficial effect

The beneficial effects of this Act are:

1. Using a laser gasification ionized metal foil to generate plasma as an ion source, cleaning and efficient, and quickly obtaining metal ions;

2. The speed at which the implanted ions hit the workpiece is fast, and the velocity is obtained by superimposing the plasma shock wave and the electric field;

3. The radiant heater is used to heat the workpiece, and the heating can increase the depth of the ion strengthening layer, increase the hardness of the injection layer, and improve the quality and efficiency of ion implantation;

4. Overcoming the problem of traditional ion implantation directivity, and simultaneously injecting metal ions and non-metal ions, and inputting reaction gas from the air inlet when non-metal ions are injected;

5. The device uses a variety of sensors and computer systems to monitor the reaction process online in real time.

DRAWINGS

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a schematic illustration of the apparatus for laser induced plasma implantation into the surface of a workpiece.

In the figure: 1 high power laser, 2 focusing lens, 3 full mirror, 4 air inlet, 5 charge receiving board, 6 workpiece, 7 working table, 8 radiant heater, 9 sealing plate, 10 lifting table bracket, 11 metal ion, 12 electrons, 13 metal foil, 14 high pressure resistant glass plate, 15 neutral particles, 16 sealing plate, 17 pulse negative high voltage source, 18 charge sensor and positive voltage source, 19 computers, 20 suction holes, 21 workpiece temperature Sensor, 22 pressure gauge, 23 pressure sensor, 24 cavity.

Embodiments of the invention

The details and operation of the method and apparatus proposed by the present invention will be described in detail below with reference to the accompanying drawings.

Work material 00Cr12 heat-resistant steel, sanding off the oxide layer on the surface of the workpiece and polishing it, then degreasing with absolute ethanol; raising the table support (10) to a certain height, and taking the pre-processed workpiece from above the cavity ( 6) Fixedly clamped on the table (7), attach the temperature sensor (21) to the surface of the workpiece, connect the pulsed negative high voltage source (17) to the side, then lower the table to the working height and adjust the radiant heater ( 8), seal the contact part (9) between the heater, the table bracket and the high pressure vacuum chamber; attach a layer of metal foil (13) to the upper glass plate (14), and then put the glass The plate cover is on the cavity, the metal foil is downward, sealed by the sealing plate (16), and then fixed by force; the air inlet hole (4) is sealed, and the gas is evacuated from the air suction hole (20) by a vacuum pump, and the pressure gauge is observed. (22), the internal pressure reaches 10-2~10-1Pa; the radiant heater power supply is turned on to heat the workpiece, and the temperature of the workpiece is controlled by the temperature sensor (21) at 600~800 °C; the positive power supply is turned on on the positive charge plate. (18), positive potential 3kv, the pulse on the workpiece is connected to the negative high voltage source (17), negative potential 60kv, pulse width 50μs, pulse repetition frequency 50Hz; start high-power neodymium glass laser (1), set the laser energy 50J, pulse width 10ns, spot diameter 8mm and other parameters by computer (19), laser shock In the metal foil, the aluminum ions in the aluminum plasma move to the surface of the workpiece at a great speed under the double action of the shock wave and the electric field to achieve ion implantation. After 5 minutes of reaction, the laser again impacts other parts of the aluminum foil to increase the aluminum ion. The concentration was repeated 3 times. After 30 minutes of reaction, all power was turned off and the workpiece was removed.

Claims

A method for laser-inducing plasma into a substrate, characterized in that a laser ablated metal foil-induced plasma is used as an ion source, and an electric field is separated, wherein a shock wave and an electric field force generated by a metal ion in a plasma explosion are accelerated. Next, it is injected into the surface layer of the substrate under heating conditions at a great speed.
A method of injecting a workpiece by laser induced plasma according to claim 1, wherein the specific implementation steps are:

(1) Grinding off the oxide layer on the surface of the workpiece with sandpaper and polishing it, then removing it with an emulsifier and anhydrous ethanol;

(2) Raise the table support, fix the pre-processed workpiece to the workbench from above the cavity, attach a temperature sensor to the surface of the workpiece, connect the pulsed negative high-voltage source connector to the side, and then lower the table to the working height and adjust The position of the radiant heater is sealed, and the contact portion between the heater, the table bracket and the high pressure resistant vacuum chamber is sealed;

(3) Put a layer of metal foil on the upper glass plate, then cover the glass plate on the cavity, the metal foil is downward, sealed by the sealing plate, and then fixed by force;

(4) Sealing the air inlet hole, pumping the gas from the air suction hole with a vacuum pump, observing the pressure gauge to make the internal pressure reach 10-3~10-1Pa;

(5) Turn on the radiant heater power supply to heat the workpiece, the temperature of the workpiece is controlled by the temperature sensor at 600~800 °C; the positive power supply is turned on on the positive charge plate, the positive potential is 3~5kv, the pulse on the workpiece is connected to the negative high voltage source, and the negative potential is 40. ~60kv, pulse width 50~100μs, pulse repetition frequency 50Hz;

(6) Turn on the laser, set the energy, pulse width and spot diameter parameters of the laser by the computer. The laser impacts the metal foil at different positions three times. After the reaction is completed, turn off all the power supplies and remove the workpiece.
Apparatus for performing a method of laser-induced plasma injecting a substrate according to claim 2, comprising: a plasma generating system, a vacuum reaction chamber system, a workpiece system, and a computer (19);

The plasma generating system comprises a high-power neodymium glass laser (1) for exciting high-energy short-pulse laser, a 45° full-mirror (3), a focusing lens (2), and a laser ablation material (13);

The vacuum reaction chamber system comprises: a cavity (24), an air inlet hole (4), a suction hole (20), a sealing plate (16) connected to the upper glass plate and the cavity, a table support, a radiant heater and a lower end of the cavity a sealed sealing plate (9), a charge receiving plate (5), a charge sensor and a positive voltage source (18), a pressure sensor (23) and a pressure gauge (22); the cavity (24) is a cylindrical sealed cavity (24) The upper glass cover is circular, the diameter of which is larger than the diameter of the cavity, and the upper glass cover and the cavity are sealedly connected by a sealing ring; the side of the side wall of the cavity (24) is above The position has an air inlet hole (4), and a lower side of the opposite side has a suction hole (20), and the air suction pump draws the cavity into a predetermined vacuum through the air suction hole (20); the cavity (24) The inner wall is uniformly disposed with four arc-shaped charge receiving plates (5) along the circumference, perpendicular to the cavity diameter strips, and the opposite two charge receiving plates (5) are arranged up and down; the charge sensor is mounted on the charge receiving plate, and the positive voltage is The source is connected to the charge receiving plate for inputting and controlling the amount of positive charge on the positive charge receiving plate; the pressure sensor (23) Located at the bottom of the cavity (24), connected to the external pressure gauge, monitoring the internal pressure of the cavity (24); there are two elliptical cylindrical legs under the cavity.
A device for injecting a plasma into a substrate according to claim 3, wherein the workpiece system comprises a table (7), a radiant heater (8), a table holder (10), and a temperature sensor. (21) and a pulsed negative high voltage source (17); the workpiece (6) is positioned and clamped to the inverted trapezoidal table (7), and the table (7) has a lifting table bracket underneath, by changing the length of the bracket The upper and lower rotation angles of the control table meet the requirements of the bevel processing; the table support (10) is cylindrical in shape, and is sealed with the cavity by a large elastic sealing ring; the radiant heater (8) is located in a recessed portion below the workbench The cylindrical portion of the radiant heater (8) and the lower end of the cavity are sealed by a sealing ring; the temperature sensor (21) is disposed on the workpiece and connected to the external temperature display meter to monitor the working temperature of the workpiece; The source (17) is connected to the workpiece to apply a negative potential to the workpiece.
A device for injecting a plasma into a substrate according to claim 3, wherein said computer (19) controls parameter setting of the laser, records changes in charge on the positive charge plate, and controls lifting of the table support .
A device for injecting a plasma into a substrate according to claim 3, wherein the vacuum chamber is a transparent high pressure glass.
The apparatus for injecting a substrate by laser induced plasma according to claim 3, wherein the radiant heater (8) is heated by radiant heating, and the heating wire is molybdenum wire, and the molybdenum wire is parallel and uniform in the same plane. Arrangement.