Electrochemical reaction device and photoelectrochemical corrosion method

Abstract

The invention provides an electrochemical reaction device which comprises an annular light source and a reaction tank, the annular light source is arranged around the reaction tank, the reaction tank comprises a tank body wall, an anode and a cathode, and the tank body wall defines an accommodating space for accommodating chemical liquid medicine; the cathode is nested in the anode so as to define a plurality of sections which are spaced in parallel between the anode and the cathode; the wall of the groove body is provided with a light-permeable window so that light beams emitted by the annular light source can penetrate through the anode to irradiate a workpiece. The ring-shaped light source is sleeved on the periphery of the reaction tank, and the light-permeable window is arranged on the tank body wall of the reaction tank to allow the light beam emitted by the ring-shaped light source to penetrate through the anode to irradiate the workpiece, so that the photo-assisted or photo-catalytic electrochemical machining process of multiple workpieces can be realized. By applying the electrochemical reaction device provided by the invention, the workpiece is fixed back to the annular light source and the anode, so that the corrosion efficiency is improved, the uniformity of lateral corrosion can be improved, and the loading and dismounting operations of the workpiece are easy to realize.

Description

Technical Field

[0001] The present invention belongs to the field of semiconductor integrated circuit manufacturing, and in particular relates to an electrochemical reaction device and a photoelectrochemical etching method. Background Art

[0002] The discovery of room-temperature photoluminescence in porous silicon has garnered widespread attention. Numerous explorations and research have focused on achieving high-aspect-ratio, well-formed porous silicon arrays, which are believed to have broad application prospects in optoelectronic materials, photodetectors, and photovoltaic conversion.

[0003] At present, conventional processes for making porous silicon arrays include deep reactive ion etching (DRI) and photoelectrochemical etching (PEE). Among them, the electrochemical etching method is the most widely used due to its simple operation, easy control, and relatively complete microchannel structure. Figure 1 This is a typical structural diagram of a single-tank electrochemical reactor, which can be used to perform photoelectrochemical etching methods. It includes a reaction tank, a cathode 042 inserted into the tank, a metal anode 041 immersed in an etching solution 07, and a workpiece. A light source 02 is suspended above the reaction tank. Using the above single-tank structure to perform photoelectrochemical etching methods has the following problems:

[0004] 1. As Figure 1 As shown, when the single-tank electrochemical reaction device performs a photoelectrochemical process, a metal anode is applied to the back of the workpiece mainly by sputtering, or the back of the workpiece is brought into contact with a conductive member such as a copper plate. In this case, when light is applied to the back of the workpiece, photocorrosion pollution will occur, thereby reducing the efficiency of the anode.

[0005] Second, due to the limitations of the structure of the above-mentioned reaction device, when performing multi-workpiece processing, for example, the current density applied between the cathode and the metal anode in the light source and the corrosion solution is inconsistent, which will affect the balance between charge transport and reaction material transport, thereby increasing the difficulty of process control. In some cases, it may even lead to deterioration of the uniformity of the microchannel pores and the structural integrity.

[0006] It should be noted that the above introduction to the technical background is merely intended to provide a clear and complete description of the technical solutions of this application and facilitate understanding by those skilled in the art. Simply because these solutions are described in the background technology section of this application, it should not be assumed that the above technical solutions are well known to those skilled in the art. Summary of the Invention

[0007] In view of the shortcomings of the prior art described above, the purpose of the present invention is to provide an electrochemical reaction device and a photoelectrochemical corrosion method to solve the problems of the existing electrochemical reaction device being used for light-assisted or photocatalytic electrochemical reactions, especially the problem that the workpiece is susceptible to corrosion when contacting with the anode during the photoelectrochemical corrosion method, and it is difficult to meet the requirements for film formation and morphological consistency of the corrosion surface when batch processing multiple workpieces, as well as the fixation of polygonal workpieces and other application requirements.

[0008] To achieve the above-mentioned and other related objectives, the present invention provides an electrochemical reaction device, comprising:

[0009] A housing is provided with an annular light source and a reaction tank, wherein the annular light source is arranged around the reaction tank, and the reaction tank comprises:

[0010] The tank wall defines a storage space for containing the chemical solution;

[0011] an anode and a cathode, the cathode being nested within the anode to define a plurality of parallel spaced segments between the anode and the cathode;

[0012] Wherein, the wall of the tank body is provided with a light-transmitting window to allow the light beam emitted by the annular light source to pass through the anode and illuminate the workpiece.

[0013] Optionally, the method further comprises: a fixing mechanism configured to hold the workpiece in a state substantially parallel to the anode, so that the workpiece is located in a section parallel to and spaced apart from the cathode and the anode and contacts the anode.

[0014] Optionally, the anode and the cathode are concentrically nested and respectively configured as cylindrical electrodes, and a plurality of parallel and spaced segments are defined between the cylindrical electrodes of the anode and the cathode. A fixing mechanism is provided in each segment, and the fixing mechanism is arranged adjacent to the anode so that each workpiece is spaced apart from the cathode at substantially equal intervals when processing multiple workpieces.

[0015] Optionally, the fixing mechanism includes a slot and a sealing ring, the slot being configured to allow the workpiece to be inserted into the slot in a snap-fit ​​manner; and / or, the sealing ring is disposed in the slot to prevent chemical liquid from penetrating into the gap between the anode and the workpiece.

[0016] Optionally, the fixing mechanism includes a pressing plate and a threaded connector, the periphery of the pressing plate is provided with an internal threaded hole matching the threaded connector, and the pressing plate is pressed onto the anode by using the threaded connector to bring the workpiece into contact with the anode.

[0017] Optionally, the fixing mechanism includes a pressure plate and a threaded connector, the pressure plate is inserted into the slot in a snap-fit ​​manner, and an airbag-type sealing ring is provided on the processing surface and the reverse side of the workpiece to fill the fitting gap between the workpiece and the pressure plate and the slot.

[0018] Optionally, the annular light source includes one or a combination of a halogen lamp and an LED lamp; and / or a lighting panel is provided adjacent to the annular light source for homogenizing the emitted light beam.

[0019] Optionally, it further includes: a temperature control system, wherein the cooling method includes one or a combination of water cooling and evaporative cooling.

[0020] Optionally, the reaction tank further includes a stirring mechanism, which includes a central shaft and multi-layer stirring paddles connected to the central shaft.

[0021] Optionally, the anode is embedded in the tank wall to form a light-transmitting window; or, the anode is arranged on the inner side of the tank wall to cover the window, wherein the material of the anode includes one of indium tin oxide ITO and fluorine-doped tin oxide FTO.

[0022] Optionally, the anode is arranged on the inner side of the tank wall around the window to form a ring electrode, and the ring electrode is a graphite electrode.

[0023] The present invention further provides a photoelectrochemical etching method, which is performed in the electrochemical reaction device according to any one of claims 1 to 10, comprising the following steps:

[0024] Providing a workpiece to be processed, wherein the workpiece includes a guide hole pre-formed on a processing surface thereof;

[0025] Fixing the workpiece on the anode by a fixing mechanism with its processing surface facing away from the anode;

[0026] A chemical solution is added into the reaction tank so that the anode, cathode and the processing surface of the workpiece are immersed in the chemical solution. The annular light source is turned on, and the anode and the cathode are energized. Under the condition that the emitted light beam passes through the anode and irradiates the opposite side of the processing surface of the workpiece, electrochemical corrosion occurs on the processing surface of the workpiece to form a channel extending from the induced hole to its depth direction.

[0027] Optionally, the photoelectrochemical etching method is used to fabricate a microstructure array of porous silicon, wherein the microstructure array includes a micropore array, a microcavity array, or a microchannel array.

[0028] As described above, in the electrochemical reaction device of the present invention, the reaction tank includes nested light-transmitting anodes and cathodes to define a plurality of parallel-spaced sections, and a fixing mechanism is used to fix the workpiece in a section of the parallel space between the anode and the cathode in a manner substantially parallel to the anode, and to form contact with the anode. By arranging an annular light source on the periphery of the reaction tank, the tank body of the reaction tank is provided with a light-transmitting window to allow the light beam emitted by the annular light source to pass through the light of the anode, thereby realizing light-assisted or photocatalytic electrochemical processing of multiple workpieces; in addition, the fixing mechanism is configured to hold the workpiece in a state substantially parallel to the anode, and the workpiece is easy to load and disassemble from the fixing mechanism, easy to realize large-scale production, and can also expand the applicable scenarios of the electrochemical reaction device, and has broad application prospects.

[0029] By applying the electrochemical reaction device of the present invention, the workpiece processing surface is held facing away from the annular light source and the anode, thereby realizing the photoelectrochemical corrosion reaction of multiple workpieces under back illumination, thereby improving the corrosion efficiency and the uniformity of lateral corrosion. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 A typical structural diagram of an electrochemical reactor showing a single-cell structure.

[0031] Figure 2 Shown is a cross-sectional view of an electrochemical reaction device according to an embodiment of the present invention.

[0032] Figure 3 Shown is a schematic top view of an electrochemical reaction device according to an embodiment of the present invention.

[0033] Figure 4 Shown is a schematic diagram of the partial structure of an electrochemical reaction device in an embodiment of the present invention.

[0034] Figure 5 for Figure 2 Exploded view of the securing mechanism shown.

[0035] Component number description

[0036] 02 Light Source

[0037] 041 Metal Anode

[0038] 042 cathode

[0039] 07 Corrosive solution

[0040] 1 Housing

[0041] 2 Ring Light Sources

[0042] 3 Lighting panels

[0043] 4 trough wall

[0044] 5 Workpiece

[0045] 6. Mixing mechanism

[0046] 7 Chemical solutions

[0047] 8 Fixing mechanism

[0048] 23 Power Supply

[0049] 41 Anode

[0050] 42 cathode

[0051] 61 Center Axis

[0052] 62 stirring paddle

[0053] 71 Drain valve

[0054] 72 Liquid inlet tank

[0055] 81 pressure plate

[0056] 82 card slots

[0057] 83 sealing ring

[0058] 84 threaded connectors

[0059] 10. Temperature Control System DETAILED DESCRIPTION

[0060] The following describes the embodiments of the present invention through specific examples. Those skilled in the art will readily understand the other advantages and benefits of the present invention from the disclosure herein. The present invention may also be implemented or applied through various other specific embodiments, and the details in this specification may be modified or altered based on different viewpoints and applications without departing from the spirit of the present invention.

[0061] For example, when describing the embodiments of the present invention in detail, for the sake of convenience, the cross-sectional views may not be partially enlarged or reduced according to the general scale, and the schematic views are only examples and should not limit the scope of protection of the present invention.

[0062] For ease of description, spatially relative terms such as "under," "below," "below," "below," "above," and "upper" may be used herein to describe the relationship of one element or feature to other elements or features shown in the drawings. It will be understood that these spatially relative terms are intended to encompass orientations of the device in use or operation other than the orientation depicted in the drawings. Furthermore, in the context of this application, a structure in which a first feature is described as being "above" a second feature may include embodiments in which the first and second features are formed in direct contact, and may also include embodiments in which another feature is formed between the first and second features, i.e., the first and second features may not be in direct contact.

[0063] It should be noted that the illustrations provided in this embodiment are only used to schematically illustrate the basic concept of the present invention. Therefore, the illustrations only show components related to the present invention and are not drawn according to the number, shape and size of components in actual implementation. In actual implementation, the type, quantity and proportion of each component can be changed at will, and the component layout type may also be more complicated.

[0064] The main principles of making porous silicon by electrochemical etching are as follows:

[0065] Si+2HF+nh+→SiF2+2H++(2-n)e - Formula (1)

[0066] SiF2+2HF→ SiF4+H2 Formula (2)

[0067] SiF4+2HF→H2SiF6 formula (3)

[0068] Among them, h + is a hole, e - is the electron, and n is the charge number.

[0069] As shown in reaction formula (1), the electrochemical corrosion method requires the participation of corrosion solution and holes. When the holes are exhausted, the electrochemical corrosion will stop, that is, the electrochemical corrosion will stop. Therefore, when preparing porous silicon, a photoelectrochemical corrosion device can be used. When the semiconductor is irradiated with light with energy higher than the semiconductor absorption threshold, the valence band electrons of the semiconductor jump from the valence band to the conduction band, generating electrons e- and holes h+. The electrons and holes generated by the light are then under the action of the electric field of the space charge layer. The holes are migrated to the surface of the semiconductor ions and undergo oxidation reaction with the electron donors in the solution.

[0070] The inventors of this application have noted that existing electrochemical reaction devices used to perform light-assisted or photocatalytic electrochemical reactions, particularly photoelectrochemical etching methods, suffer from poor surface consistency in the simultaneous processing of multiple workpieces. This is due to the contact between commonly used metal anodes and the workpieces, which makes the anodes susceptible to photocorrosion during the process. To improve the efficiency of anode use and enhance the structural integrity and morphological consistency of the processed materials, the present invention provides an electrochemical reaction device.

[0071] Hereinafter, the electrochemical reaction device provided by the present invention will be described in detail with reference to the accompanying drawings.

[0072] Example 1

[0073] See also Figure 2 This embodiment provides an electrochemical reaction device, including a shell 1, in which an annular light source 2 and a reaction tank are arranged. The annular light source 2 is arranged around the reaction tank. The reaction tank includes a tank wall 4, an anode 41 and a cathode 42. The tank wall 4 defines a storage space for accommodating chemical liquid.

[0074] Figure 3 The figure shows a top view of an electrochemical reaction device according to an embodiment of the present invention. Nested within the housing 1, from the outside inward, are an annular light source 2, an anode, and a cathode 42. The annular light source 2 can be configured to emit light with a wavelength spectrum exceeding 400 nm, and the annular light source 2 can have an appropriate spectral range. The cathode 42 is nested within the anode 41, with the workpiece 5 to be processed secured between the anode and cathode 42. The anode is configured to connect to the positive terminal of a power source 23, while the cathode 42 is configured to connect to the negative terminal of the power source 23. The cathode is positioned at a predetermined distance from the workpiece 5 to increase the uniformity of the electric field.

[0075] For example, when an electrochemical reaction device is used to perform a light-excited electrochemical corrosion method, the annular light source 2 may preferably be a halogen light source or an LED light source. The spectral range of the LED light source is 400nm to 600nm, and the spectral range of the halogen light source is 400nm to 1100nm. The annular light source uses a light source type with a smaller spectral range, which will cause the excited holes to be farther away from the reaction interface, and the number of holes reaching the tip pit is small, resulting in a slow reaction speed at the tip of the channel, but it is easy to maintain the relative stability between material transport and charge transport.

[0076] The anode 41 and cathode 42 plates may be concentrically disposed and define a plurality of parallel and spaced segments therebetween. Figure 3As shown, the anode and cathode can each have a cylindrical electrode plate, and the cylindrical electrode plates of the two can generally enclose a regular polygon with the same number of side lengths. Since the cylindrical electrode plates of the anode and cathode are nested in parallel, when electrochemical reactions are performed on multiple workpieces in the reaction tank, the spacing between different workpieces and the cathode is basically equal, so that the current density applied to different workpieces does not vary much. This enables batch electrochemical processing of multiple workpieces, greatly improving processing efficiency and increasing the uniformity of the electrochemical reaction. In some embodiments, the anode 41 can be made of a semiconductor electrode made of a thin film material with high transmittance and high conductivity, including but not limited to indium tin oxide (ITO), fluorine-doped tin oxide (FTO), zinc tin oxide (ZTO), or similar conductive glass, so that the light beam emitted by the ring-shaped light source can pass through the anode 41 to provide light to the opposite side of the workpiece processing surface. The "high transmittance" mentioned here can refer to a situation where the transmittance is above 80%. In other embodiments, the anode 41 can be configured as a ring-shaped anode. The ring-shaped electrode itself can be an inert electrode with electrode stability, such as a graphite electrode. The ring-shaped electrode is configured to allow only a small portion of the light beam emitted from the ring-shaped light source to be blocked, while the majority of the light beam passes through the area defined by the ring-shaped electrode and irradiates the workpiece. Compared to the method of using a metal anode to form contact with the workpiece, by using a semiconductor electrode and an inert electrode as the anode, photocatalytic metal corrosion can be avoided, the service life of the electrode can be increased, the frequency of electrode replacement can be reduced, and the efficiency of electrode use can be improved. Regardless of the material used for the anode 41, the cathode 42 can be an inert electrode, such as a graphite electrode, or a metal electrode, such as a platinum electrode, or other materials with low load.

[0077] In some embodiments, a light-gathering plate 3 with a light-homogenizing function is provided on the side of the annular light source facing the reaction tank, which includes but is not limited to a light diffusion plate, a scattering plate or a similar light-gathering plate. The light-gathering plate 3 can be integrally formed or a multi-section combination. Figure 4 Shown is a schematic diagram of the partial structure of the electrochemical reaction device in an embodiment of the present invention. The light-collecting plate 3 shown is arranged adjacent to the annular light source 2 to increase the uniformity of the luminous flux reaching the workpiece; preferably, the light-collecting plate 3 is detachably spliced ​​into a polygonal ring surface by multiple panels, which is conducive to the later inspection, life testing and replacement of the light source, and can reduce the maintenance cost of the device.

[0078] Return to see Figure 2In one implementation, the anode 41 can be embedded in the tank wall 4 to form a light-transmitting window. The anode itself is made of a thin film material with high light transmittance and high conductivity. The tank wall 5 and the bottom of the shell together define the accommodating space of the reaction tank. The reaction tank can be equipped with an independent liquid inlet system, and the liquid inlet system includes a delivery pipeline. One end of the delivery pipeline can be connected to a container for storing chemical liquid, and the other end can supply chemical liquid to the liquid inlet tank 72 via a liquid inlet (not shown). In some embodiments, the liquid inlet system includes an inlet valve configured to control the flow rate and / or the amount of chemical liquid. The reaction tank also includes a drain port 71 located at the bottom of the shell for discharging used chemical liquid. A drain valve is provided downstream of the drain port for controlling the opening or closing of the flow path from the accommodating space of the reaction tank to the drain port. In another embodiment, the drain valve can be configured as a flow valve to adjust the flow rate and discharge volume of the waste liquid discharged from the reaction tank. The drain port 71 can be further connected to a mechanical pump via a discharge pipeline fluid, and the mechanical pump is configured to provide power for extracting the waste liquid; alternatively, the drain port 71 can also recycle the discharged chemical liquid after use via a bypass pipeline.

[0079] In another embodiment, the anode 41 is removably mounted on the inner surface of the tank wall 4. The anode 41 can be made of a highly transparent film material. The transparent anode can cover the transparent window of the tank wall 4, so that most of the light emitted from the ring-shaped light source passes through the transparent anode through the window and illuminates the workpiece. Alternatively, an annular electrode can be made of an inert material, such as a graphite electrode, and can be arranged around the window so that most of the light emitted from the ring-shaped light source passes through the window and the area defined by the annular electrode and illuminates the workpiece. The tank wall 4 can be provided with multiple transparent windows, and the geometric shape and size of the transparent windows can be determined based on the pattern and area to be processed.

[0080] The workpiece 5 to be processed can be fixed in the reaction tank by a fixing mechanism 8, and the fixing mechanism 8 is configured to hold the workpiece 5 to be processed substantially parallel to the anode 41. Figure 5 The fixing mechanism 8 can be provided with multiple groups of fixing mechanisms, each group of fixing mechanisms is configured to place a workpiece 5 between a section parallel to and spaced apart from the cathode 43 and the translucent anode, and each group of fixing mechanisms includes a card slot and a sealing ring, the card slot is configured to allow the workpiece to be inserted into the card slot while being in contact with the anode, and the sealing ring is arranged in the card slot and in contact with the outer periphery of the workpiece to prevent chemical liquid from penetrating into the gap between the workpiece and the anode.

[0081] Figure 5The diagram shows the structure of the fixing mechanism of the present invention. The fixing mechanism 8 may include a slot 82 and a sealing ring 83. The slot 82 may be configured to allow the workpiece 5 to be processed to be inserted therein in a snap-fit ​​manner. The sealing ring 83 may be disposed in the slot to secure the workpiece 5 in place. For example, the workpiece is fixedly disposed at a specific position within the slot so as to be attached to the light-transmitting anode, while simultaneously filling the gap between the workpiece and the slot to provide an airtight barrier to the chemical solution. The workpiece may include a regular or irregular sheet, plate, strip, or block-shaped workpiece or sample, with the workpiece having a circular, polygonal, or similarly regular cross-section.

[0082] In some embodiments, the fixing mechanism 8 further includes a pressure plate 81 and a threaded connector 84. The pressure plate 81 is removably mounted on the anode 41 and positioned on one side of the workpiece's machining surface. The pressure plate applies a force that forces the workpiece's reverse side of the machining surface against the anode 41, thereby forming contact. Preferably, the pressure plate 81 may include an appropriate hollowed-out area to fully expose the workpiece's machining area to the ionic current in the chemical solution. The geometry and dimensions of the pressure plate may be determined based on the desired machining pattern; for example, it may be configured to be slightly larger than the area of ​​the pattern to be processed or machined / etched. In some embodiments, the pressure plate 81 and the workpiece 5 are each inserted into the slot 82 with a clearance fit. The pressure plate 81 includes an internally threaded hole disposed on its periphery, which mates with the threaded connector 84. The threaded connector 84 forces the pressure plate 81 against the workpiece's machining surface, causing the reverse side of the workpiece's machining surface to abut against the anode, thereby forming contact. Compared with the way in which a metal anode forms contact with a workpiece, the workpiece is contacted with its machined surface facing away from the anode through a threaded connection, which can avoid the influence of metal corrosion and facilitate the loading and unloading operations of the workpiece self-fixing mechanism.

[0083] In a specific embodiment, sealing rings 83 are provided on the processing surface and the reverse surface of the workpiece, that is, each set of fixing mechanisms includes sealing rings 83 arranged in pairs. The sealing rings 83 are preferably airbag sealing rings, which can better adapt to various workpiece shapes and fill the fitting gap between the workpiece and the card slot 82. The pressure plate can be pressed against the workpiece 5 through the airbag sealing ring, which is convenient for installing and unloading the workpiece to be processed, and is used to provide flexible support between the pressure plate and the workpiece.

[0084] The reaction tank further includes a temperature control system 10, which can be configured to maintain the chemical solution within the reaction tank within a desired temperature range. The temperature control system 10 can include a temperature display system and a temperature sensor (not shown). The temperature display system communicates with the temperature sensor to monitor temperature changes of the chemical solution within the reaction tank in real time. In some embodiments, the temperature control system 10 further includes a cooling assembly configured to control the process temperature within the reaction tank using one or a combination of water cooling and evaporative cooling in response to the detected temperature of the chemical solution exceeding a set process temperature.

[0085] As an additional method, the reaction tank further includes a stirring mechanism 6 for promoting the photocatalytic or light-assisted electrochemical reaction to occur more uniformly on the surface of the workpiece. Figure 2 As shown, the stirring mechanism 6 can be arranged inside the cylindrical cathode 42, and includes a central shaft 61 and a multi-layer stirring paddle 62 connected to the central shaft. The central shaft 61 and the multi-layer stirring paddle 62 can be an integrally formed part, and the stirring mechanism 6 as a whole can be made of corrosion-resistant material, such as tetrafluoroethylene.

[0086] Example 2

[0087] The present application also provides a photoelectrochemical etching method, which is performed on the electrochemical reaction device described in the previous embodiment and includes the following steps:

[0088] S1: providing a workpiece to be processed, wherein the workpiece includes an induction hole pre-formed on a processing surface thereof;

[0089] S2: fixing the workpiece on the anode by a fixing mechanism with the workpiece's processing surface facing away from the anode;

[0090] S3: Add chemical liquid into the reaction tank so that the anode, cathode and the processing surface of the workpiece are immersed in the chemical liquid, turn on the annular light source, and energize the anode and the cathode. Under the condition that the emitted light beam passes through the anode and irradiates the opposite side of the processing surface of the workpiece, electrochemical corrosion occurs on the processing surface of the workpiece to form a channel extending from the induced hole to its depth direction.

[0091] The above-described photoelectrochemical etching method can be applied to the preparation of porous silicon microstructure arrays, including but not limited to porous silicon micropore arrays, microcavity arrays, microchannel arrays, or porous silicon arrays of similar structures. Hereinafter, the photoelectrochemical etching method will be specifically described using its application to the preparation of porous silicon arrays as an example, but the present invention is not intended to be limited thereto.

[0092] Specifically, at step S1, the workpiece can be a silicon wafer, an SOI wafer, or other workpiece to be processed / oxidized; before step S1, the silicon material on the surface of the workpiece is anisotropically etched based on a graphic mask by, for example, a wet etching method to obtain a workpiece with induced holes on the processed surface.

[0093] Step S2: The workpiece 5 is mounted on the fixture 8 and pressed against the anode 41 with its machined surface facing away. This creates contact between the workpiece and the anode. The reaction tank can then be closed. Using a ring-shaped light source to backlight the machined surface of the workpiece improves lateral etching at the channel opening, resulting in a better surface quality for the workpiece.

[0094] Furthermore, by selecting a ring-shaped light source with a small spectral range, such as an LED light source, the excited holes are farther away from the reaction interface, and the number of holes reaching the tip pit is small, resulting in a slow reaction speed at the tip of the channel. However, it is easy to maintain the relative stability between material transport and charge transport. Combined with the appropriate process temperature, it is conducive to producing smoother channel sidewalls.

[0095] The workpiece 5 is assembled to the fixture by inserting the workpiece 5 into the retaining slot 82 in a snap-fit ​​manner, with the workpiece's machining surface facing the cathode and in full contact with the chemical solution, and its reverse surface in contact with the anode, receiving the light beam emitted from the annular light source 2 and passing through the light-transmitting anode. In some embodiments, a sealing ring is disposed in the retaining slot 82 to provide an airtight barrier to the chemical solution, significantly reducing corrosion of the non-machined surfaces of the workpiece.

[0096] Step S3: Add chemical solution into the reaction tank so that the anode, cathode, and the workpiece processing surface are immersed in the chemical solution; turn on the ring light source 2 and turn on the power supply 23 (for example, via Figure 2 The power line 231 shown is used to energize the anode and the cathode, so that the emitted light beam passes through the anode and irradiates the opposite side of the workpiece processing surface, forming a channel extending from the induced hole to its depth direction on the processing surface of the workpiece.

[0097] In some examples, the workpiece is held substantially parallel to the anode, specifically by being inserted into a slot in a snap-fit ​​manner. A sealing ring fills the gap between the workpiece and the slot, allowing the reverse side of the workpiece's processed surface to receive the light beam without contacting the chemical solution. Because the annular light source surrounds the reaction tank, an increase in the temperature of the chemical solution within the tank can cause a decrease in carrier scattering and ion mobility. During the photoelectrochemical etching process, the temperature of the chemical solution can be controlled to maintain a desired process temperature, for example, below room temperature.

[0098] Power is supplied to the light-transmitting anode and the cathode, and a photoelectrochemical etching method is performed based on the pre-formed induced pits, forming channels extending from the induced pits to their depths. During the formation of the microchannel silicon array, the current density near the microchannel tip is changed by adjusting the power supply, the process temperature is maintained at through the temperature control system 10, and the oxidation time is set. For example, the chemical solution 7 can be a mixture containing nitric acid, sulfuric acid, potassium nitrate, and ethylene glycol. The chemical solution 7 can be stored in a container of the liquid inlet system. The chemical solution can be introduced into the liquid inlet tank 72 via a delivery pipeline, and the flow rate of the chemical solution introduced into the liquid inlet tank 72 is controlled by an inlet valve (not shown).

[0099] After performing the above steps, the drain valve is opened to discharge the used chemical liquid from the drain port 71 and the processed workpiece is taken out.

[0100] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the present invention. Anyone skilled in the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by one of ordinary skill in the art without departing from the spirit and technical principles disclosed herein are intended to be covered by the claims of the present invention.

Claims

1. An electrochemical reaction device, characterized in that: include: A housing is provided with an annular light source and a reaction tank, wherein the annular light source is arranged around the reaction tank, and the reaction tank comprises: The tank wall defines a storage space for containing the chemical solution; an anode and a cathode, the cathode being nested within the anode to define a plurality of parallel spaced segments between the anode and the cathode; Wherein, the wall of the tank body is provided with a light-transmitting window to allow the light beam emitted by the annular light source to pass through the anode and illuminate the workpiece.

2. The electrochemical reaction device according to claim 1, characterized in that Also includes: The fixing mechanism is configured to hold the workpiece in a state substantially parallel to the anode, so that the workpiece is located in a section parallel to and spaced apart from the cathode and the anode and contacts the anode.

3. The electrochemical reaction device according to claim 1, wherein: The anode and the cathode are concentrically nested and are respectively arranged as cylindrical electrodes. The cylindrical electrode of the anode includes one of a semiconductor electrode and an inert electrode. A plurality of parallel and spaced segments are defined between the cylindrical electrodes of the anode and the cathode. A fixing mechanism is provided in each segment. The fixing mechanism is arranged adjacent to the anode so that each workpiece is spaced apart from the cathode at a substantially equal distance when processing multiple workpieces.

4. The electrochemical reaction device according to claim 1, wherein: The fixing mechanism includes a slot and a sealing ring, wherein the slot is configured to allow the workpiece to be inserted into the slot in a snap-fit ​​manner; and / or the sealing ring is arranged in the slot to prevent chemical liquid from penetrating into the gap between the anode and the workpiece.

5. The electrochemical reaction device according to claim 1, wherein: The fixing mechanism includes a pressing plate and a threaded connector. The periphery of the pressing plate is provided with an internal threaded hole matched with the threaded connector. The threaded connector is used to press the pressing plate onto the anode so that the workpiece is in contact with the anode.

6. The electrochemical reaction device according to claim 4, characterized in that: The fixing mechanism includes a pressure plate and a threaded connector. The pressure plate is inserted into the slot in a snap-fit ​​manner. Airbag sealing rings are provided on the processing surface and the reverse surface of the workpiece to fill the fitting gap between the workpiece and the pressure plate and the slot.

7. The electrochemical reaction device according to claim 1, characterized in that: The annular light source includes one or a combination of a halogen lamp and an LED lamp; and / or a lighting plate is provided adjacent to the annular light source for homogenizing the emitted light beam.

8. The electrochemical reaction device according to claim 1, characterized in that Also includes: The temperature control system adopts a cooling method including water cooling and evaporative cooling or a combination thereof.

9. The electrochemical reaction device according to claim 1, characterized in that: The reaction tank further comprises a stirring mechanism, which comprises a central shaft and multi-layer stirring paddles connected to the central shaft.

10. The electrochemical reaction device according to claim 1, characterized in that: The anode is embedded in the tank wall to form a light-transmitting window; or, the anode is arranged on the inner side of the tank wall to cover the window, wherein the material of the anode includes one of indium tin oxide ITO and fluorine-doped tin oxide FTO.

11. The electrochemical reaction device according to claim 1, characterized in that: The anode is arranged on the inner side of the tank wall around the window to form a ring electrode, and the ring electrode is a graphite electrode.

12. A photoelectrochemical corrosion method, characterized in that: The photoelectrochemical corrosion method is performed in the electrochemical reaction device according to any one of claims 1 to 11, comprising the following steps: Providing a workpiece to be processed, wherein the workpiece includes a guide hole pre-formed on a processing surface thereof; Fixing the workpiece on the anode by a fixing mechanism with its processing surface facing away from the anode; A chemical solution is added into the reaction tank so that the anode, cathode and the processing surface of the workpiece are immersed in the chemical solution. The annular light source is turned on, and the anode and the cathode are energized. Under the condition that the emitted light beam passes through the anode and irradiates the opposite side of the processing surface of the workpiece, electrochemical corrosion occurs on the processing surface of the workpiece to form a channel extending from the induced hole to its depth direction.

13. The photoelectrochemical etching method according to claim 12, wherein: The invention relates to a microstructure array for producing porous silicon, wherein the microstructure array comprises a micropore array, a microcavity array, or a microchannel array.

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