CN108526627B - Laser-electrochemical composite micromachining method and device for semiconductor material - Google Patents

Abstract

The invention discloses a laser-electrochemical composite micromachining method and device for semiconductor materials, belonging to the field of special processing, wherein the method utilizes the characteristic that the conductivity of semiconductor materials such as monocrystalline silicon is obviously enhanced along with the rise of temperature, the semiconductor materials are heated by laser beams, the conductivity of materials near a processing area is enhanced in a localized manner, a conductive channel through which current preferentially passes is formed, electrolytic processing is introduced in a bias electric beam manner on the basis, the laser-electrochemical self-coupling composite processing near the processing area is realized, tool setting is not needed, the adhesion of surface residues in the laser processing process is not ensured, the cooling effect can be strengthened, and the purposes of reducing thermal damage, reducing residual stress and improving the quality of the processed surface are achieved; the device comprises a laser, an external light path, an electrolytic power supply and a stable jet flow generating device; the device can generate stable low-voltage electrolyte jet flow, realize the regulation of the impact angle and the position and ensure the accurate regulation of the relative position of the laser beam and the impact jet flow.

Description

Laser-electrochemical composite micromachining method and device for semiconductor material

Technical Field

The invention relates to a processing method and a device for processing structures such as micro-slits, holes, grooves and the like in the field of special processing, in particular to a laser electrolysis composite processing method and a device which are realized by utilizing the temperature sensitivity characteristic of the conductivity of semiconductor materials such as monocrystalline silicon and the like.

Background

Semiconductor materials represented by silicon and germanium have good structural properties and functional properties, and are widely applied to the fields of chips, photovoltaics, medical instruments, micro-electro-mechanical systems and the like. Processing a microstructure with a specific morphology on the surface of a semiconductor material can realize multiple functions, such as: the submicron-scale periodic microgroove structure can enhance the anti-reflection performance of the surface of the material; the honeycomb-shaped tightly distributed smooth micro-pit groups can form a micro-concave lens array; the surface regular microstructure is beneficial to changing the hydrophilic performance of the material and realizing super-hydrophilic and super-hydrophobic functions; the difference of hydrophilicity caused by different micro-morphologies generates surface tension difference at a critical area, and can drive the liquid drop to move autonomously.

The high brittleness and low fracture toughness of the semiconductor material are limited, the material processability is poor, and the micro-processing difficulty is higher. The micro-machining of the materials is favored by scientific research institutions at home and abroad for many years, and currently, the micro-machining/milling, electrolytic machining, photoetching machining, chemical etching machining, laser machining and the like are mainly adopted. The processing method has various characteristics, application occasions and limitations. For example, when single crystal silicon is processed by micro end milling, in order to ensure that material removal occurs in a ductile region to avoid generation of cracks, the feeding amount of a single step needs to be controlled below 250nm, so that the material removal efficiency is low; when photoetching processing is adopted, the process is complex, the requirements on equipment such as a photoetching machine are high, and different types of base materials with different crystal orientations have different requirements on corrosive agents, so that the method is more suitable for stabilizing the base materials and causes lower processing efficiency; the traditional laser processing semiconductor material is always accompanied with relatively obvious thermal damage large-scale production; when the electrochemical dissolution method is adopted, the current density is often lower than that of the gold phenomenon due to the characteristics of semiconductor materials, and the advanced ultrafast laser represented by femtosecond laser has the defects of low removal efficiency, expensive equipment and the like.

Aiming at the micromachining of semiconductor materials, composite machining methods are also proposed at home and abroad, and the micromachining aims are fulfilled by reasonably matching and using the means such as mechanical force, laser, electrochemical anodic dissolution, electrochemical discharge, chemical corrosion, water jet impact and the like.

After searching the prior art, the inventor of Tangwarodomnukun V and the like puts forward a laser water jet composite processing technology for realizing micro-grooving of monocrystalline silicon materials in the text of "insulation of hybrid laser-water jet alignment of silicon substrates", wherein nanosecond pulse laser is utilized to heat a brittle material, the softened material is immediately impacted and removed by bias high-pressure water jet, micro-cracks can be effectively avoided, meanwhile, the high-pressure water jet has a forced cooling effect, the thermal damage control is facilitated, and the thermal damage on one side of the groove edge can be controlled within 20 mu m. However, the technique has its own limitations, which are manifested in that the surface edge and inner wall of the micro-groove are rough, the groove bottom depth fluctuation is large, and meanwhile, the high-pressure jet impact intervenes, so that residual stress may exist on the processed surface.

U.S. patent publication No. US2017/0120345a1 discloses a method and apparatus for laser enhanced diamond drilling. According to the method, materials with high hardness and good light transmittance, such as diamond, are embedded in the axis of the metal drill bit, laser can pass through the material to be processed without damage in the processing process, the material is irradiated on the surface of the material to be processed, and the material near the contact area of the drill bit is heated and softened, so that the local hard and brittle material is converted into a ductile material, the drilling efficiency is improved, the drilling quality is improved, and the abrasion of a cutter is reduced. The method can be used for processing hard and brittle materials such as ceramics, semiconductors and the like, and realizes the manufacture of a 1mm drill bit. However, the diameter of the hole drilled by this method depends on the size of the drill bit, and the structure of the diamond material embedded in the drill bit makes the manufacture complicated and further reduction of the diameter of the drill bit difficult, which may limit the application of this method in the field of micro-machining.

Chinese patent publication No. CN106735866A discloses an apparatus and method for processing semiconductor material by combining multi-focus laser and electrochemistry. The method comprises the steps of enabling a laser beam with adjustable parameters to act on the back of a semiconductor sample from bottom to top, exciting a large number of photo-generated holes from the semiconductor sample, and enabling the holes to move to the surface of the semiconductor sample to participate in electrochemical reaction to form material corrosion. Meanwhile, the tool electrode is used as a cathode, the semiconductor sample is used as an anode, and the electric spark discharge machining under the high potential condition and the electrochemical corrosion removal under the low potential condition can be realized by controlling the potential between the two electrodes. The method combines the multi-focus laser and the electrochemistry on the semiconductor sample, and can improve the etching efficiency and the surface quality of the through hole. However, in the method, the laser beam and the electrode need to be precisely subjected to tool setting to realize combined machining, and the requirement on the precision of the device is high.

Chinese patent publication No. CN1919514A discloses a jet liquid beam and laser coaxial composite processing method, which introduces a high-speed jet liquid beam coaxial with a laser beam to remove materials by electrolysis on the basis of laser processing by using a water-guided laser processing technology for reference, and eliminates a recast layer, micro cracks and residual stress. The method focuses on the high-quality and high-efficiency processing of fine holes, seams, grooves and other structures with the size of 0.25-1.5 mm in the fields of aerospace, weaponry and the like, takes metal materials as processing objects, and does not relate to the related properties of semiconductor materials. In addition, limited to the diameter and mass of the jet, the beam quality of the laser beam is reduced during the coaxial conduction in the jet, which may cause the light spot to diverge, making further reduction of the machining size difficult.

Morin F J and Maita J P, as reported in "electric properties of silicon containing sensing and boron", show a tendency of a sharp increase in Electrical conductivity with an increase in temperature in the temperature range between the normal temperature and the melting point of single crystal silicon (Electrical conductivity of about 25.6S/m at 328 ℃ C. and about 27372.2S/m at 1335 ℃ C.). Based on the characteristics, for example, a local temperature field can be generated in the monocrystalline silicon material, the conductivity of the material can be enhanced in a localized mode, and therefore localized electrolytic processing of the semiconductor material is achieved. But related technical literature is not queried.

Disclosure of Invention

Based on the characteristic that the conductivity of semiconductor materials such as silicon is enhanced along with the increase of temperature, the invention proposes that a local conductivity enhanced region is induced and generated near a processing region by utilizing the irradiation of short-pulse laser to form an instantaneous localized conductive channel through which current preferentially passes, and the electrolysis effect is enhanced in a localized manner; meanwhile, laser can timely erode a passivation layer which is possibly generated, and the cooperative processing of laser thermal effect and electrochemical anode dissolution self-coupling is continuously realized, so that the micro-processing method with high processing efficiency, small thermal damage and good surface quality is obtained, and meanwhile, a special processing device for the method is provided.

In order to achieve the purpose, the invention is realized by the following technical scheme:

a laser-electrochemical composite micromachining method for semiconductor material features that the electric conductivity of semiconductor material is increased along with the temp rise, and the laser beam is focused to generate local temp field and electrochemical anode is used for dissolving, so effectively eliminating recast layer and residual stress and improving machining quality; the laser is characterized in that a laser beam emitted by a laser is irradiated on a semiconductor material, and a metal thin film layer is arranged on the lower end face of the semiconductor material; the metal film layer is connected with the positive electrode of the direct current pulse power supply, so that the potential of the lower surface of the semiconductor material is uniformly distributed; the negative pole of the direct current pulse power supply is connected with the metal needle head, so that the electrolyte communicated in the metal needle head is cathodically changed; the electrolyte forms a thin electrolyte layer on the upper surface of the semiconductor material; the metal film layer is isolated from the outside through an insulating layer, so that a localized conductive channel between a positive electrode and a negative electrode of the direct current pulse power supply only passes through a semiconductor material.

Further, the semiconductor material is a semiconductor material with conductivity positively correlated to temperature, and is especially monocrystalline silicon.

Furthermore, the electrolyte in the metal needle head is a high-concentration neutral saline solution, and the mass fraction of the electrolyte is 25-40%.

A semiconductor material laser electrochemical composite micromachining device comprises a light path system, a stable low-pressure jet flow generating and adjusting system and an electrolytic machining system; the optical path system comprises a laser, an optical gate, a beam expander, a vibrating mirror and a reflective mirror; laser beams emitted by the laser pass through the optical shutter, then pass through the beam expanding lens, are reflected by two reflecting mirrors arranged at an angle of 45 degrees, and then are irradiated on the semiconductor material through the vibrating mirror; the electrolytic processing system comprises a direct current pulse power supply, a metal film layer and an insulating layer; the metal film layer is arranged on the lower surface of the semiconductor material; the metal film layer is isolated from the outside through an insulating layer, so that a localized conductive channel between a positive electrode and a negative electrode of the direct-current pulse power supply can be generated only through a semiconductor material; the stable low-pressure jet flow generation system comprises a metal needle, electrolyte is introduced into the metal needle, and the electrolyte forms a thin electrolyte layer on the upper surface of the semiconductor material.

Further, the stable low-pressure jet flow generating and adjusting system further comprises a servo motor, a ball screw, an electrolyte cylinder and a piston rod; the servo motor is connected with the ball screw through a coupler; the ball screw drives the piston rod to move left and right through the sliding block; a piston is arranged at the end part of the piston rod; the piston is matched with the electrolyte cylinder; the electrolyte in the electrolyte cylinder enters the metal needle through the hose to form stable low-pressure jet flow.

Further, a first check valve and a second check valve are mounted on the electrolyte cylinder; when the servo motor rotates reversely, the ball screw drives the piston rod to retreat stably, the first one-way valve is closed, the second one-way valve is opened, and electrolyte in the electrolyte tank enters the electrolyte cylinder through the filter under the action of pressure difference; when the servo motor rotates forwards, the ball screw drives the piston rod to move forwards stably, the first one-way valve is opened, the second one-way valve is closed, and electrolyte in the electrolyte cylinder enters the metal needle through the hose under the pushing of the piston rod to form stable low-pressure jet flow.

Furthermore, an angle regulator is installed at one end of the metal needle head, so that the jet impact angle can be adjusted, and the jet impact position is adjusted by an XYZ three-way adjusting platform.

Further, the device also comprises an infrared camera, a high-speed camera, a hydrophone and a current probe; the signal changes detected by the current probe and the hydrophone are displayed by an oscilloscope, and the imaging signals detected by the high-speed CCD camera and the infrared camera can be displayed by a computer.

Further, the laser is a nanosecond or picosecond pulse laser.

Further, electrolyte recovery filter equipment for electrolyte is retrieved.

Has the advantages that:

(1) aiming at the problem of poor processing manufacturability of semiconductor materials such as monocrystalline silicon and the like, the characteristic that the conductivity of the semiconductor materials such as monocrystalline silicon and the like is enhanced along with the rise of temperature is utilized, and laser processing and electrochemical anode dissolution are combined, so that the processing method with high processing efficiency, small thermal damage and good surface quality is realized, and the processing problems of a large number of structures such as fine slits, holes, grooves and the like with the sizes of 30-200 mu m in the packaging and cutting of integrated circuit chips and the processing and manufacturing of micro semiconductor parts of micro electro mechanical systems are solved.

(2) The invention utilizes the temperature sensitive characteristic of the conductivity of semiconductor materials such as monocrystalline silicon and the like to convert a local high-temperature area generated in the material by laser irradiation into a high-conductivity area to form a localized conductive channel through which current preferentially passes, wherein the current density is far higher than that of the surrounding normal-temperature material area, so that the electrochemical anode dissolution is limited near the laser irradiation area, the self-coupling cooperative processing of the laser thermal effect and the electrochemical anode dissolution is realized, the processing localization is improved, the processing quality is improved, and the defect that the composite processing can be realized only by strictly relying on a tool setting step is avoided.

(3) The method of the invention takes laser processing as the main part, reasonably utilizes the characteristic that the conductivity of semiconductor materials such as monocrystalline silicon and the like is enhanced along with the rise of temperature, realizes the composite processing of laser processing and electrochemical anode dissolution by introducing low-pressure electrolyte beams into electrolytic processing, can ensure higher processing efficiency, and can effectively reduce laser thermal damage and eliminate recast layers and residual stress through electrochemical anode dissolution. In the processing process, the laser can timely remove a passivation layer possibly generated, and the continuous electrolytic processing is ensured. Meanwhile, the impact action of the low-pressure electrolyte beam at the adjacent position of the processing area leads the surface of the material to be subjected to the continuous forced cooling action, thus being beneficial to further reducing the heat damage; in addition, plasma is generated in the thin electrolyte layer above the processing area through laser irradiation, local strong micro stirring is generated through modes of bubble collapse and the like, processing products are taken away, a flow field is improved, and processing quality is improved.

(4) Forming an instantaneous localized high-temperature region in a semiconductor material such as monocrystalline silicon along the axial direction of a laser beam by utilizing the localization of laser heating; an external electric field is introduced near a processing area by using an impact electrolyte beam, and current preferentially passes through a conductivity enhancement area in the material to form an instantaneous localized conductive channel, so that the localized enhancement of current density is realized, and the dissolution of a local electrochemical anode is accelerated. In addition, in the laser pulse gap, due to the continuity of the temperature field change in the cooling process, a high-temperature area in the material still exists for a period of time, the localized electrolytic machining is continued, the post-treatment of the laser machining surface is realized, and the aims of reducing the thermal damage, reducing the residual stress and improving the surface quality are fulfilled.

(5) The processing system of the invention has perfect functions and is easy to assemble and realize. The designed stable low-pressure jet flow generating system is simple in structure and easy to install and maintain.

Drawings

FIG. 1 is a schematic system diagram of a laser electrolysis hybrid machining method according to the present invention;

fig. 2 is a schematic structural diagram of the stable low pressure jet generating system of fig. 1 according to the present invention.

The reference numbers are as follows:

1. a laser, 2, a laser beam, 3, an optical shutter, 4, a beam expander, 5, a vibrating mirror, 6, a reflector, 7, a stable low-voltage jet flow generating and regulating system, 8, a metal needle, 9, a thin electrolyte layer, 10, a semiconductor material, 11, an insulating protective layer, 12, a metal film layer, 13, a direct current pulse power supply, 14, a current probe, 15, a localized conducting channel, 16, a hydrophone, 17, an oscilloscope, 18, an electrolyte recovery and filtering device, 19, a high-speed CCD camera, 20, a computer, 21, an infrared camera, 8, a metal needle, 22, a jet flow angle regulator, 24, a hose, 25, a first one-way valve, 26, an electrolyte cylinder, 27, a piston, 28, a piston rod, 29, a slide block, 30, a ball screw, 31, a first support seat, 32, a servo motor, 33, a coupler, 34, a second support seat, 35, a second one-way valve, 36, a fixed-, Electrolyte tank, 37, filter, 38, XYZ three-way regulation platform.

Detailed Description

For a further understanding of the present invention, reference will now be made to the following descriptions taken in conjunction with the accompanying drawings:

example 1: the embodiment is a semiconductor material laser electrolysis composite processing method based on a localized conductive channel, and the laser beam 2 generated by a laser 1 is focused on the surface of a semiconductor material 10 after being adjusted and transmitted by an external light path, and efficient material removal is carried out by utilizing a laser thermal effect, so that micropore and microgroove processing is completed. Meanwhile, the laser thermal effect generates a local temperature field at the periphery of the micropore, and the conductivity of semiconductor materials such as monocrystalline silicon and the like is enhanced in a localized mode. On the basis, a stable low-voltage electrolyte beam generating and adjusting device is used for introducing a bias electrolyte beam, and an electrochemical anode is locally introduced to dissolve in a region with enhanced conductivity at the periphery of a laser irradiation region, so that a recast layer and residual stress can be effectively eliminated, and the processing quality is improved. In the composite processing process, the laser beam thermal effect can destroy and eliminate a passivation layer possibly generated in electrolytic processing, and the composite processing is ensured to be continuously carried out.

The electrolyte is a neutral saline solution, and can also generate acid solutions such as dilute hydrochloric acid and the like; the neutral saline solution is a neutral saline solution with proper concentration, and the mass fraction is 20-40%; the mass fraction of the dilute hydrochloric acid solution is 5-15%.

Example 2: with reference to fig. 1, the present embodiment is a semiconductor material laser electrolysis composite processing system based on localized conductive channels, which includes a light path system, a stable low-pressure jet generating and adjusting system, and an electrolytic processing system; the optical path system comprises a laser 1 and an external optical path, wherein the external optical path comprises a shutter 3, a beam expander 4, a vibrating mirror 5 and a reflector 6. Laser 1 outputs laser beam 2, passes through protective device optical gate 3, expands laser beam diameter by beam expanding lens 4, adjusts direction by reflector 6, and finally uses vibrating mirror 5 to control beam motion form, irradiates to semiconductor material 10 surface, and forms localized conducting channel 15 in semiconductor material 10. The generation of the laser beam 2 and the movement of the galvanometer 5 are controlled by a computer 20.

The present example also includes a stable low pressure jet generating and regulating system 7, the constant velocity electrolyte produced forms a stable low pressure jet after passing through a metal needle 8, and is jetted to the surface of the semiconductor material 10 to form a thin electrolyte layer 9.

The electrolyte recycling and filtering device 18 is also arranged in the embodiment, and is beneficial to recycling the electrolyte.

The present example also includes an electrochemical machining system comprising a dc pulse power supply 13 having a cathode connected to the metal needle 8 to "cathodically" the jet and an anode connected to the metal film layer 12 on the lower surface of the semiconductor material 10 to uniformly distribute the potential on the lower surface. The metal film layer 12 is coated with an insulating layer 11 to ensure that the inter-electrode conductive path is only generated through the semiconductor material 10.

The present example also includes a combined machining process detection system comprising a current probe 14, a hydrophone 16, a high-speed CCD camera 19 and an infrared camera 21, wherein signal variations detected by the current probe 14 and the hydrophone 16 can be represented by an oscilloscope 17, and imaging signals detected by the high-speed CCD camera 19 and the infrared camera 21 can be represented by a computer 20.

Example 3: with reference to fig. 2, the embodiment of the stable low-pressure jet generating and adjusting system includes a servo motor 32 driving a ball screw 30 to rotate through a coupling 33, and two ends of the ball screw 30 are supported by a first support seat 31 and a second support seat 34; the rotation of the ball screw 30 is converted into the linear motion of the piston rod 28 by the slide block 29 matched with the ball screw 30, so that the electrolyte in the electrolyte cylinder 26 is pushed to be output at a constant speed. The electrolyte flows into the metal needle 8 through the first one-way valve 25 and the hose 24 to form stable low-pressure jet flow. The low pressure jet angle is adjustable by the angle adjuster 22 and the jet impingement position is adjustable by the XYZ three-way fine adjustment stage 38. The first check valve 25 and the second check valve 35 can realize the output and the suction of the electrolyte by matching with the forward and reverse movement of the ball screw 30. When the servo motor 32 drives the piston rod 28 to move forward through the ball screw 30, the first one-way valve 25 is opened, the second one-way valve 35 is closed, and the electrolyte enters the hose 24 under the pushing of the piston 27; when the servo motor 32 drives the piston rod 28 to move reversely through the ball screw 30, the first check valve 25 is closed, the second check valve 35 is opened, and the electrolyte in the electrolyte tank 36 is sucked into the electrolyte tank 26 through the filter 37.

The working process is as follows:

step one, a servo motor 32 drives a piston rod 28 to retreat at a constant speed through a coupler 33 and a ball screw 30, a first one-way valve 25 is closed, a second one-way valve 35 is opened, and electrolyte in an electrolyte tank 36 is sucked into an electrolyte cylinder 26 under the action of air pressure difference;

step two, the servo motor 32 drives the piston rod 28 to advance at a constant speed through the coupler 33 and the ball screw 30, the first one-way valve 25 is opened, the second one-way valve 35 is closed, and the electrolyte in the electrolyte cylinder 26 enters the metal needle 8 through the hose 24 to form stable electrolyte jet flow;

thirdly, the stable electrolyte jet flow impacts the surface of the semiconductor material 10, and a thin electrolyte layer 9 with stable thickness is formed near an impact area; the position of the jet impact area is adjusted by using the angle adjuster 22 and the XYZ three-way adjusting platform 38;

step four, switching on a direct current pulse power supply 13 to form an electrochemical machining current loop;

step five, controlling the output of the laser beam 2 through a computer 20, adjusting the radiation position of the laser beam to be near the impact position of the stable liquid beam through optical elements such as a beam expander 4, a reflector 6 and a vibrating mirror 5, and passing through a thin electrolyte layer 9 to be focused on the surface of the semiconductor material 10;

sixthly, controlling the laser beam to move by using a vibrating mirror 5, and processing microstructures such as required holes, grooves, seams and the like;

seventhly, in the machining process, detecting instruments such as a high-speed CCD camera 19, an infrared camera 21, a current probe 14, a hydrophone 16 and the like are used for observing the phenomena of heat transfer and mass transfer, current change and the like, so that the monitoring of the machining process is realized;

step eight, after the processing is finished, the laser 1 and the direct current pulse power supply 13 are closed, and the servo motor 32 is stopped to rotate;

the present invention is not limited to the above-described embodiments, and any obvious improvements, substitutions or modifications can be made by those skilled in the art without departing from the spirit of the present invention.

Claims (11)

1. A laser-electrochemical composite micromachining method for semiconductor material features that the electric conductivity of semiconductor material is increased along with the temp rise, and the laser beam is focused to generate local temp field and electrochemical anode is used for dissolving, so effectively eliminating recast layer and residual stress and improving machining quality; the laser is characterized in that a laser beam (2) emitted by a laser (1) is irradiated on a semiconductor material (10), and a metal thin film layer (12) is arranged on the lower end face of the semiconductor material (10); the metal film layer (12) is connected with the positive electrode of the direct current pulse power supply (13), so that the potential of the lower surface of the semiconductor material (10) is uniformly distributed; the negative electrode of the direct current pulse power supply (13) is connected with the metal needle (8) to ensure that the electrolyte communicated with the metal needle (8) is cathodically changed; the electrolyte forms a thin electrolyte layer (9) on the upper surface of the semiconductor material (10); the metal film layer (12) is isolated from the outside through an insulating layer (11), so that a localized conductive channel (15) between a positive electrode and a negative electrode of the direct current pulse power supply (13) only passes through the semiconductor material (10).

2. The laser-electrochemical composite micromachining method of semiconductor material according to claim 1, characterized in that the semiconductor material (10) is a semiconductor material whose electrical conductivity is positively correlated with temperature.

3. The laser-electrochemical composite micromachining method for semiconductor materials according to claim 1, characterized in that the electrolyte in the metal needle (8) is a high-concentration neutral saline solution with a mass fraction of 25% -40%.

4. The laser-electrochemical composite micromachining method of semiconductor material according to claim 2, characterized in that the semiconductor material (10) is monocrystalline silicon.

5. A semiconductor material laser electrochemical composite micromachining device comprises an optical path system, a stable low-pressure jet flow generating and adjusting system (7) and an electrolytic machining system; the device is characterized in that the optical path system comprises a laser (1), an optical gate (3), a beam expander (4), a vibrating mirror (5) and a reflector (6); laser beams (2) emitted by the laser (1) pass through an optical shutter (3), then pass through a beam expanding lens (4), are reflected by two reflectors (6) arranged at an angle of 45 degrees, and then are irradiated on a semiconductor material (10) through a vibrating lens (5); the electrolytic machining system comprises a direct current pulse power supply (13), a metal film layer (12) and an insulating layer (11); the metal film layer (12) is arranged on the lower surface of the semiconductor material (10); the metal film layer (12) is isolated from the outside through an insulating layer (11), so that a localized conductive channel (15) between a positive electrode and a negative electrode of the direct current pulse power supply (13) can be generated only through the semiconductor material (10); the stable low-pressure jet flow generation system (7) comprises a metal needle (8), electrolyte is introduced into the metal needle (8), and the electrolyte forms a thin electrolyte layer (9) on the upper surface of the semiconductor material (10).

6. The semiconductor material laser-electrochemical composite micromachining apparatus according to claim 5, characterized in that the stable low-pressure jet generating and regulating system (7) further includes a servo motor (32), a ball screw (30), an electrolyte cylinder (26), and a piston rod (28); the servo motor (32) is connected with the ball screw (30) through a coupling (33); the ball screw (30) drives the piston rod (28) to move left and right through the sliding block (29); a piston (27) is arranged at the end part of the piston rod (28); the piston (27) is matched with the electrolyte cylinder (26); electrolyte in the electrolyte cylinder (26) enters the metal needle (8) through the hose (24) to form stable low-pressure jet flow.

7. The laser-electrochemical composite micromachining apparatus for semiconductor material according to claim 6, characterized in that a first check valve (25) and a second check valve (35) are mounted on the electrolytic solution cylinder (26); when the servo motor (32) rotates reversely, the ball screw (30) drives the piston rod (28) to retreat stably, the first one-way valve (25) is closed, the second one-way valve (35) is opened, and electrolyte in the electrolyte tank (36) enters the electrolyte cylinder (26) through the filter (37) under the action of pressure difference; when the servo motor (32) rotates forwards, the ball screw (30) drives the piston rod (28) to move forwards stably, the first one-way valve (25) is opened, the second one-way valve (35) is closed, and electrolyte in the electrolyte cylinder (26) enters the metal needle (8) through the hose (24) under the pushing of the piston rod (28) to form stable low-pressure jet flow.

8. The semiconductor material laser electrochemical composite micromachining apparatus according to claim 6 or 7, characterized in that an angle adjuster (22) is installed at one end of the metal needle (8) so that a jet impact angle is adjustable, and a jet impact position is adjusted by an XYZ three-way adjusting platform (38).

9. The laser-electrochemical composite micromachining apparatus for semiconductor materials according to claim 5, further comprising an infrared camera (21), a high-speed camera (19), a hydrophone (16), and a current probe (14); the signal changes detected by the current probe (14) and the hydrophone (16) are represented by an oscilloscope (17), and imaging signals detected by a high-speed CCD camera (19) and an infrared camera (21) can be represented by a computer (20).

10. The combined laser-electrochemical micromachining apparatus of semiconductor materials according to claim 5, characterized in that the laser (1) is a nanosecond or picosecond pulsed laser.

11. The semiconductor material laser-electrochemical composite micromachining apparatus according to claim 5, further comprising an electrolyte recovery filter (18) for electrolyte recovery.

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