CN101249580B - Electrochemistry-laser mask focusing micro etch method for processing and device thereof - Google Patents

Abstract

The invention relates to an electrochemical-laser mask focusing micro-etching processing method and device, belonging to the field of micro-processing of manufacturing technology. The method is characterized in that material removal is the combined result of laser shock and electrochemical reaction, and the method is suitable for microfabrication of conductive metal-like materials. The processing method and device are: the laser beam emitted by the laser is uniformly modulated and beam expanded by the beam modulator, and then passes through the mask plate with carved patterns, and then uses the imaging focusing lens to shrink the pattern on the mask plate, and passes through the mask plate. The conductive glass above the workpiece is imaged on the surface of the workpiece. There is a passivating electrolyte between the conductive glass and the workpiece, the positive pole of the electrochemical processing power supply is connected to the workpiece, and the negative pole of the power supply is connected to the conductive glass. During the processing, the laser beam forms plasma between the electrolyte and the workpiece and rapidly expands to generate shock waves, which deform and remove the passivation layer of the processing part on the surface of the workpiece; the workpiece in the processing area where the passivation layer is destroyed The material is dissolved and etched; the etching process of the microstructure is realized. The invention can effectively improve the processing efficiency, fineness and processing precision of complex graphics.

Description

Electrochemical-laser mask focusing micro-etching processing method and device

technical field

The invention relates to the field of micromachining in manufacturing technology, in particular to an electrochemical-laser mask focusing microetching processing method and device, which are suitable for non-contact etching processing of microstructures of conductive metal materials or semiconductor materials.

Background technique

At present, the demand for micro-manufacturing technology of precision MEMS devices is very urgent. The microfabrication technology originating from the semiconductor integrated circuit manufacturing process has not been limited to the silicon wafer exposure and etching technology in the IC process. Electrochemical processing, laser processing and its composite processing technology have also been applied in the field of microfabrication. The electrochemical-laser composite micromachining technology uses the high energy and focus of the laser to reduce the activation energy of the electrode reaction, which can make the electrochemical reaction easier to occur and control the action area of the electrochemical reaction.

There are two main types of combined electrochemical and laser processing: laser-enhanced (or induced) electrochemical deposition and laser-electrochemical composite etching. According to the retrieved data, there are many researches on laser-electrochemical deposition at home and abroad, but less research on laser-electrochemical composite etching. Among them, Pajak, P.T. of the United Kingdom studied the composite etching processing technology of electrolyte beam injection and laser beam, using the injection device to spray the cathodically polarized electrolyte onto the surface of the workpiece, and the laser beam is irradiated along the coaxial direction of the electrolyte beam In the processing area, the conductive metal material used as the anode is electrochemically etched. Due to the irradiation of the laser beam, the current density of the electrochemical reaction is significantly increased, and the etching speed can reach 10 μm/s. However, in order to ensure the coaxial irradiation of the laser beam and the electrolyte beam, the laser must pass through the electrolyte injection cavity, so that part of the energy of the laser is absorbed by the electrolyte, and the bubbles in the electrolyte will also affect the conduction of the beam. Inevitably cause loss of laser energy. On the other hand, although the diameter of the laser beam can be controlled at the micron level, it is difficult to apply this method to the field of microfabrication due to the large action area of the electrolyte beam.

Electrochemical-laser composite etching processing technology has also made some progress in China. The national patent "Excimer Laser Electrochemical Microstructure Manufacturing Method and Device" Patent No.: CN1259598C proposes to first use the photolithography plate-making process of integrated circuits to make arrays Micro-probe electrode, add electrolyte between the substrate to be processed and the micro-probe electrode; after power-on, excimer laser is used to irradiate the processing area from above the probe electrode to control the electrochemical reaction and realize the micro-structure processing of the substrate. The disadvantage of this method is that: the manufacturing precision of the micro-probe electrode will definitely affect the processing of the substrate, and the achieved processing fineness is restricted by the probe electrode; the laser will be blocked by the electrode when it is irradiated from above the probe electrode. The laser light can only be irradiated to the gaps of the array electrodes, but not directly to the processed parts on the substrate facing the electrodes.

Contents of the invention

The purpose of the present invention is to solve the problems existing in the above-mentioned electrochemical-laser composite micro-etching process, and propose an electrochemical-laser masking process with high processing fineness and good controllability of the processing area, which is suitable for metal or semiconductor materials. Method and device for mold-focused micro-etching.

An electrochemical-laser mask-focused micro-etching processing method is characterized in that: the laser beam emitted by the laser passes through the mask focusing optical path, and the reduced micro-pattern is imaged on the surface of the workpiece; between the workpiece and the electrolyte due to high The shock wave generated by the power density laser removes the passivation layer; at the same time, under the action of electrochemical reaction, the workpiece material at the removal part of the passivation layer is corroded and dissolved; the electrochemical-laser mask focus etching process is completed.

In the aforementioned electrochemical-laser mask focusing micro-etching processing method, the energy of the laser beam emitted by the laser is 1-30 joules, the pulse time is 10-100 nanoseconds, and the spot mode of the laser is fundamental mode or multi-mode.

The device for realizing the above-mentioned electrochemical-laser mask focusing microetching processing method includes a laser and a mask focusing optical path, which is characterized in that: a composite processing and detection part is provided, and according to the advancing direction of the laser beam, the laser and the mask focusing Optical path, compound processing and detection part. The compound processing and detection part is composed of conductive glass, electrolyte tank, workpiece, voltmeter, ammeter, and electrochemical processing power supply. The negative electrode of the electrochemical processing power supply is connected to the conductive glass as the cathode, and the ammeter is connected in series between them to detect the processing current; the power supply The positive electrode of the machine is connected to the workpiece as the anode, and the voltmeter is connected in parallel with the workpiece and the conductive glass to detect the processing voltage.

In the above device, the mask focusing optical path for laser beam transmission is: laser → 45° mirror → beam spatial modulator → mask plate → focusing lens. The laser beam with the mask pattern is finally imaged on the surface of the workpiece by the focusing lens through the conductive glass.

The present invention is realized according to the following technical solutions:

(1) The workpiece to be processed is installed in the electrolyte tank, the conductive glass is installed and fixed above the workpiece, the workpiece is connected to the positive pole of the processing power supply, the conductive glass is connected to the negative pole of the power supply, and a voltmeter and an ammeter are added to the circuit to form an electrochemical process. In the processing system, after the circuit is connected, fill the electrolyte tank with electrolyte, and completely immerse the workpiece to the bottom surface of the conductive glass;

(2) The electrochemical machining power supply is energized, and the output voltage of the control power supply is used to generate a passivation layer on the surface of the workpiece under the action of the electrolyte, so that the electrochemical reaction of the workpiece enters a stagnant state;

(3) The pulsed laser is generated by the laser according to the optimized parameters, and then irradiates the surface of the workpiece through the mask focusing optical path and conductive glass, forming plasma between the workpiece and the electrolyte and expanding rapidly, generating shock waves, so that the surface of the workpiece is irradiated with laser. The part passivation layer is deformed and removed;

(4) Under the action of electrochemical reaction, the workpiece material in the processed area where the passivation layer is destroyed is dissolved and etched away. As the laser pulse enters the gap period, the passivation layer is gradually formed in this area. In the next laser pulse cycle, The destruction of the passivation layer and the erosion of the workpiece material will occur again in the processing area, and the etching process of the microstructure is realized by using multiple pulsed laser shocks and electrochemical reactions;

The present invention has the following technical advantages:

(1) The mask plate is installed between the beam spatial modulator and the focusing mirror, and the focusing mirror can be used to reduce the mask pattern to be imaged on the surface of the workpiece. The ratio of the mask plate pattern and the actual imaging micro-pattern is 3:1 or 5:1 . Moving the mask back and forth along the direction of the optical path can change the imaging magnification of the template pattern on the surface of the workpiece, and use the same size mask to process patterns with different sizes and the same structural features. The manufacturing cost of the mask plate can be significantly reduced, and the manufacturing precision can also be improved.

(2) Conductive glass is used as the tool cathode for electrochemical machining. It forms an electric field in the electrolyte between the tool and the workpiece and can also pass through the laser beam with a mask pattern to destroy the passivation layer on the surface of the workpiece that hinders the electrochemical reaction. In addition to being a processing medium for electrochemical reactions, the electrolyte also serves as a confinement layer for laser shock, which can take away excess heat and reduce the thermal impact of processing on materials.

(3) The shock wave effect of the laser will produce a strong stirring effect in the electrolyte, which is very beneficial to the removal of electrochemical reaction products, and the electrochemical reaction can dissolve the sputtering residue generated by the laser shock into the electrolyte, thereby obtaining Well-defined microstructure.

(4) Use the passivation layer to realize electrochemical localized micro-etching, and use the laser mask to focus to realize the re-image processing of the mask pattern, and the electrochemical reaction occurs in the processing area; the non-processing area is protected by the passivation layer, and does not occur Material erosion; so as to achieve the effect of high processing fineness, good controllability of processing area, and high processing efficiency of complex graphics.

Description of drawings

Figure 1 is a schematic diagram of electrochemical-laser mask-focused microlithography processing.

Label names in Figure 1: 1. Laser, 2. Laser beam 3. 45° reflector, 4. Beam spatial modulator, 5. Mask plate, 6. Imaging focusing mirror, 7. Conductive glass, 8. Passivation Electrolyte, 9, electrolyte tank, 10, workpiece, 11, voltmeter, 12, ammeter, 13, electrochemical processing power supply.

Detailed ways

The details and working conditions of the specific device proposed by the present invention will be described in detail below in conjunction with FIG. 1 .

The device for implementing the method includes a sequentially connected laser 1, a mask focusing optical path and a compound processing and detection part. The mask focusing optical path includes three 45° reflectors 3, a beam spatial modulator 4, a mask plate 5 and an imaging focusing mirror 6; the composite processing and detection part consists of a conductive glass electrode 7, an electrolyte tank 9, a workpiece 10, and a voltmeter 11 , ammeter 12 and processing power supply 13 are formed.

The laser generates a laser beam 2 with an energy of 1-30 joules and a pulse time of 10-100 nanoseconds. The laser spot mode can be selected from the fundamental mode or multi-mode, and the laser parameters (spot size, pulse width, laser energy, and beam mode) can be adjusted. control. The shock wave generated by the laser between the electrolyte and the workpiece is mainly used to destroy the passivation layer on the surface of the workpiece without causing plastic deformation on the workpiece. Therefore, the power density of the laser is not high, and a medium-power high-frequency laser can be used. Therefore, the equipment cost of the laser is reduced, and the processing efficiency can be improved.

The laser beam 2 emitted by the laser is uniformly modulated and beam expanded by the spatial modulator 3 and then shines on the mask 4. The laser beam can pass through the hollow part of the mask with graphics, and the rest of the laser beam is blocked by the mask. Can not pass through. The transmitted laser beam has the required structural graphics, and then utilizes the focusing lens 6 to shrink into fine graphics and image them on the surface of the workpiece 10. Adjust the distance between the focusing lens 6 and the workpiece 10, so that the size of the graphics on the surface of the workpiece is the same as the microscopic graphics. Compatible with processing requirements.

The circuit connection of the electrochemical processing part includes that the workpiece 10 is connected to the positive pole of the processing power supply 13, the conductive glass 7 is connected to the negative pole of the power supply 13, and a distance of 2 to 5 mm is kept between the conductive glass and the workpiece. The voltmeter and ammeter in the circuit are used for Check processing status. The electrolyte uses a passivating electrolyte with a mass concentration of 15% to 30%, and the electrolyte completely immerses the workpiece to the bottom surface of the conductive glass.

According to different processing materials, select the corresponding electrolyte composition and concentration, so that the surface of the workpiece will form a passivation layer under the action of the electrolyte. The laser beam generated by the laser passes through the beam modulator, mask plate and focusing mirror of the optical system, and then passes through the conductive glass electrode and electrolyte to act on the surface of the workpiece. Between the workpiece and the electrolyte, due to the high energy of the laser, plasma is formed and expands rapidly, generating shock waves to destroy the passivation layer. Under the corrosion action of the electrochemical reaction, the workpiece material is dissolved and etched away in the area where the passivation layer is destroyed; with the end of the laser pulse, the passivation layer is gradually formed in these areas. Under the multiple impacts of the pulsed laser and the combined action of the electrochemical reaction, the required micro-pattern structure can be etched on the surface of the workpiece.

Claims (1)

1. an electrochemistry--laser mask focusing micro etch processing method; It is characterized in that: the laser beam that is sent by laser instrument passes through the mask focusing light path; The micrographics that will dwindle is imaged on the surface of the work of metal material, and the shock wave that between workpiece and electrolyte, is produced by the laser of high power density is removed passivation layer, simultaneously under the electrochemical reaction effect; The workpiece material that passivation layer is removed the position dissolving that is corroded realizes that the electrochemistry-laser mask focusing micro etch processes; Concrete steps comprise:

(1) processed workpiece is installed in the electrolytic bath, and electro-conductive glass is mounted on the workpiece top, and workpiece and processing power source positive pole are linked to each other; Electro-conductive glass links to each other with power cathode; Add voltmeter and ammeter in the circuit, thereby constitute the electrochemistry system of processing, after circuit connects; In electrolytic bath, charge into electrolyte, fully the bottom surface of submergence workpiece to electro-conductive glass;

(2) electrochemistry processing power source energising, the output voltage of control power supply makes surface of the work under the electrolyte effect, generate passivation layer, makes the electrochemical reaction of workpiece get into dead state;

(3) produce pulse laser by laser instrument by parameters optimization; Behind mask focusing light path and electro-conductive glass, shine surface of the work; Between workpiece and electrolyte, form plasma and expand rapidly, produce shock wave, the working position passivation layer of surface of the work laser radiation is deformed be removed; The laser beam energy that laser instrument sends is that 1～30 joule, burst length were 10～100 nanoseconds, and the facular model of laser is basic mode or multimode;

(4) under the effect of electrochemical reaction; The dissolved erosion of the ruined machining area workpiece material of passivation layer removes, and along with laser pulse gets into the gap phase, this zone forms passivation layer again gradually; At next laser pulse in the cycle; Passivation layer can take place machining area once more destruction and workpiece material erosion remove, and utilize pulse laser repeatedly to impact and electrochemical reaction, realize the etching processing of fine structure.

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