A method for wafer surface treatment

Abstract

The present invention discloses a method for wafer surface treatment, comprising: disposing a light shielding plate provided with a light transmissive slit on one side of the first surface of the wafer; removing the thin film on the first surface of the wafer by means of a photoelectrochemical etching process, or thinning the thin film on the first surface of the wafer by means of a photoelectrochemical etching process, such that the height difference between any position on the side of the thin film away from the wafer and the first surface is less than a preset value; wherein the first surface of the wafer and the second surface of the wafer are oppositely disposed, and the second surface of the wafer is the surface on which an epitaxial layer is provided for the wafer; the light shielding plate is used for shielding the light emitted by the light source in the photoelectrochemical etching process, such that the light emitted by the light source passes through the light transmissive slit and irradiates a first region, and the first region at least partially covers the thin film on the first surface. Embodiments of the present invention can, while removing or thinning the thin film on the first surface of the wafer, not affect the thickness of other regions of the first surface of the wafer and do not affect subsequent lithography processes.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor technology, and particularly to a method for wafer surface treatment. Background Art

[0002] Since there is a gap between the first surface of the wafer and the wafer stage, when epitaxial film is grown on the front side of the wafer, gas enters the first surface of the wafer along the gap between the first surface of the wafer and the stage, and then an epitaxial film grows in a circle on the first surface of the wafer. The thicker the epitaxial film grows on the front side of the wafer, the more obvious the film on the first surface is. This abnormal situation on the first surface of the wafer will lead to abnormal dimensions in the subsequent lithography process, and then lead to abnormal yield.

[0003] Currently, the abnormal film on the first surface of the wafer is removed by chemical mechanical polishing (CMP) on the first surface of the wafer to remove the epitaxial film in a circle. Since the CMP process is a whole grinding and cannot perform fixed-point grinding, the overall thickness difference of the wafer after grinding becomes larger, which will also affect the subsequent lithography process. Summary of the Invention

[0004] The present invention provides a method for wafer surface treatment to remove or thin the film on the first surface of the wafer while not affecting the thickness of other areas on the first surface of the wafer and not affecting the subsequent lithography process.

[0005] According to one aspect of the present invention, there is provided a method for wafer surface treatment, including:

[0006] A light-shielding plate provided with a light-transmitting slit is disposed on one side of the first surface of the wafer;

[0007] The film on the first surface of the wafer is removed by an electro-chemical etching process, or the film on the first surface of the wafer is thinned by an electro-chemical etching process, so that the height difference between any position on the side of the film away from the wafer and the first surface is less than a preset value;

[0008] Wherein, the first surface of the wafer and the second surface of the wafer are oppositely arranged, and the second surface of the wafer is the surface where the epitaxial layer is provided on the wafer; the light-shielding plate is used to block the light emitted by the light source in the electro-chemical etching process, so that the light emitted by the light source passes through the light-transmitting slit and irradiates on the first area, and the first area at least partially covers the film on the first surface.

[0009] Optionally, removing the film on the first surface of the wafer by an electro-chemical etching process, or thinning the film on the first surface of the wafer by an electro-chemical etching process, so that the height difference between any position on the side of the film away from the wafer and the first surface is less than a preset value, includes:

[0010] Move the wafer or move the light shield so that the light passing through the light-transmitting slit irradiates a second area, which is not completely the same as the first area.

[0011] Optionally, at least part of the second area covers the thin film.

[0012] Optionally, the thin film is an annular thin film;

[0013] Moving the wafer or moving the light shield so that the light passing through the light-transmitting slit irradiates the second area includes:

[0014] Rotating the wafer or rotating the light shield so that the light passing through the light-transmitting slit irradiates the second area.

[0015] Optionally, after removing the thin film on the first surface of the wafer by photoelectrochemical etching process or thinning the thin film on the first surface of the wafer by photoelectrochemical etching process so that the height difference between any position on the side of the thin film away from the wafer and the first surface is less than a preset value, it further includes:

[0016] Performing chemical mechanical polishing treatment on the first surface of the wafer.

[0017] Optionally, removing the thin film on the first surface of the wafer by photoelectrochemical etching process or thinning the thin film on the first surface of the wafer by photoelectrochemical etching process so that the height difference between any position on the side of the thin film away from the wafer and the first surface is less than a preset value includes:

[0018] Immersing the wafer and the thin film in an etching solution, or spraying the etching solution onto the thin film on the first surface of the wafer through a nozzle.

[0019] Optionally, before removing the thin film on the first surface of the wafer by photoelectrochemical etching process or thinning the thin film on the first surface of the wafer by photoelectrochemical etching process so that the height difference between any position on the side of the thin film away from the wafer and the first surface is less than a preset value, it further includes:

[0020] Setting a first electrode on the first surface of the wafer;

[0021] Removing the thin film on the first surface of the wafer by photoelectrochemical etching process or thinning the thin film on the first surface of the wafer by photoelectrochemical etching process so that the height difference between any position on the side of the thin film away from the wafer and the first surface is less than a preset value includes:

[0022] Inputting a first potential signal to the first electrode and inputting a second potential signal to the second surface of the wafer; wherein, the first potential signal is less than the second potential signal;

[0023] Remove the film on the first surface of the wafer by using an optoelectrochemical etching process, or thin the film on the first surface of the wafer by using an optoelectrochemical etching process. After the height difference between any position on the side of the film away from the wafer and the first surface is less than a preset value, the following steps are further included:

[0024] Remove the first electrode.

[0025] Optionally, removing the first electrode includes:

[0026] Remove the first electrode by using wet etching.

[0027] Optionally, the material of the first electrode includes at least one of platinum, gold, glassy carbon, and ruthenium-titanium.

[0028] Optionally, the material of the wafer includes silicon, gallium arsenide, silicon carbide, gallium nitride, or diamond;

[0029] The light source includes an ultraviolet light source;

[0030] The material of the light shield includes polyurethane.

[0031] Optionally, the etching solution includes at least one of hydrofluoric acid, potassium hydroxide, sulfuric acid, nitric acid, potassium persulfate, and potassium peroxymonosulfate complex salt.

[0032] In the embodiment of the present invention, an optoelectrochemical etching process is used to etch the film on the first surface of the wafer. By arranging a light shield with a light-transmitting slit on one side of the first surface of the wafer to block the wafer, the light emitted by the light source passes through the light-transmitting slit and only irradiates the film on the first surface of the wafer, so that the optoelectrochemical etching process can accurately remove or thin the film without affecting the thickness of other areas on the first surface of the wafer, and thus will not affect the subsequent lithography process.

[0033] It should be understood that the content described in this part is not intended to identify the key or important features of the embodiments of the present invention, nor is it used to limit the scope of the present invention. Other features of the present invention will become easily understood through the following description. Description of the Drawings

[0034] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0035] Figure 1It is a flowchart of a wafer surface treatment method provided by an embodiment of the present invention;

[0036] Figure 2 It is a process flow diagram of an optoelectrochemical etching provided by an embodiment of the present invention;

[0037] Figure 3 It is a schematic diagram of a thin film;

[0038] Figure 4 It is a flowchart of another wafer surface treatment method provided by an embodiment of the present invention;

[0039] Figure 5 It is a process flow diagram of another optoelectrochemical etching provided by an embodiment of the present invention. Detailed implementation manners

[0040] In order to enable those skilled in the art to better understand the solution of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0041] It should be noted that the terms "first", "second", etc. in the specification and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects, and do not necessarily need to describe a specific order or sequence. It should be understood that such data can be interchanged under appropriate circumstances so that the embodiments of the present invention described herein can be implemented in an order different from those illustrated or described herein. In addition, the terms "comprising" and "having" and any variations thereof are intended to cover non-exclusive inclusion. For example, a process, method, system, product or device comprising a series of steps or units does not necessarily have to be limited to those steps or units clearly listed, but may include other steps or units not clearly listed or inherent to these processes, methods, products or devices.

[0042] It should be understood that various forms of the flowcharts shown above can be used, steps can be reordered, added or deleted. For example, the steps described in the present invention can be executed in parallel, sequentially or in a different order, as long as the desired results of the technical solution of the present invention can be achieved, and no limitations are imposed herein.

[0043] An embodiment of the present invention provides a wafer surface treatment method, Figure 1 It is a flowchart of a wafer surface treatment method provided by an embodiment of the present invention. Refer to Figure 1 , the wafer surface treatment method includes:

[0044] S110. Place a light-shielding plate with a light-transmitting slit on one side of the first surface of the wafer.

[0045] S120. Use an optoelectrochemical etching process to remove the thin film on the first surface of the wafer, or use an optoelectrochemical etching process to thin the thin film on the first surface, so that the height difference between any position on the side of the thin film away from the wafer and the first surface is less than a preset value; wherein, the first surface of the wafer and the second surface of the wafer are oppositely arranged, and the second surface of the wafer is the surface where the epitaxial layer of the wafer is provided; the light-shielding plate is used to block the light emitted by the light source in the optoelectrochemical etching process, so that the light emitted by the light source passes through the light-transmitting slit and irradiates the first area, and the first area at least partially covers the thin film on the first surface of the wafer.

[0046] Wherein, Figure 2 is a process flow diagram of an optoelectrochemical etching provided by an embodiment of the present invention. Refer to Figure 2 , the thin film 11 is an abnormal structure generated on the first surface 101 of the wafer 10 during the process of epitaxially growing a thin film on the second surface of the wafer 10. Therefore, the thin film 11 is made of the same material as the wafer 10, and the area of the thin film 11 is smaller than the area of the first surface 101 of the wafer 10. The light-shielding plate 20 is made of a light-impermeable material, and only the light-transmitting slit 21 is light-transmitting. The photon energy of the light emitted by the light source is greater than the band gap of the thin film 11. Exemplarily, the light source can be an ultraviolet light source.

[0047] The first area at least partially covers the thin film 11 on the first surface 101 of the wafer 10, that is, the first area covers part or all of the thin film 11 on the first surface 101 of the wafer 10. The light transmitted through the light-transmitting slit 21 irradiates the thin film 11, and does not irradiate the area on the first surface 101 of the wafer 10 that does not need to be etched. For example, it does not irradiate other areas on the first surface 101 of the wafer 10 except the thin film 11. The shape of the light-transmitting slit 21 can be the same as or similar to the shape of the thin film 11. The size of the light-transmitting slit 21 can be determined according to the size of the thin film 11 and the light-emitting angle of the light source, etc., as long as it is ensured that the light transmitted through the light-transmitting slit 21 irradiates the surface of the thin film 11, and does not irradiate other areas on the first surface 101 of the wafer 10 except the thin film 11, so as to ensure that only the thin film 11 is etched. A light-shielding plate with a light-transmitting slit 21 matching the thin film can be selected according to the size of the thin film 11 to improve the etching accuracy. The preset value can be set according to the requirements of subsequent lithography processes.

[0048] The principle of removing the thin film by the photoelectrochemical etching process is as follows: The light emitted by a light source with a specific wavelength irradiates the surface of the thin film 11 through the light-transmitting slit 21, exciting the thin film 11 to generate photo-generated electron-hole pairs. Under the action of an electric field, the electron-hole pairs are separated. The holes gather on the surface of the thin film 11, and oxidation corrosion reactions and other side reactions occur. The electrons move towards the cathode and reduction reactions occur. During the oxidation corrosion process, it mainly includes two parts: the formation and dissolution of oxides. Among them, different chemical reactions occur during the dissolution process of oxides in different solution environments. Taking a silicon carbide wafer as an example, the following chemical reactions occur during the formation and dissolution of oxides:

[0049] SIC+8h + +4H2O=SIO2+CO2+8H + ;

[0050] In acidic conditions: SIO2+4H + =SI 4+ +2H2O;

[0051] In alkaline conditions: SIO2+2OH - =SIO3 2- +H2O.

[0052] It can be seen from the chemical reactions that increasing the generation rate of holes and reducing the proportion of side reactions can improve the etching reaction rate, and the oxide layer is continuously formed and dissolved during the whole process. During the photoelectrochemical etching process, the light intensity, the type and concentration of the etching solution, etc. affect the etching reaction rate and the surface morphology. The etching reaction rate can be made relatively fast by adjusting the light intensity, the type and concentration of the etching solution, etc., so that the surface thin film can be quickly removed or thinned.

[0053] In the embodiment of the present invention, the photoelectrochemical etching process is used to etch the thin film 11 on the first surface 101 of the wafer 10, and by arranging the light-shielding plate 20 provided with the light-transmitting slit 21 on one side of the first surface of the wafer 10 to shield the wafer 10, the light emitted by the light source irradiates the thin film 11 on the first surface of the wafer 10 through the light-transmitting slit 21, so that the photoelectrochemical etching process can accurately remove the thin film 11 or thin the thin film 11 without affecting the thickness of other areas on the first surface of the wafer 10, and thus will not affect the subsequent lithography process.

[0054] Optionally, using the photoelectrochemical etching process to remove the thin film on the first surface of the wafer, or using the photoelectrochemical etching process to thin the thin film on the first surface of the wafer, so that the height difference between any position on the side of the thin film away from the wafer and the first surface is less than a preset value, includes:

[0055] Moving the wafer or moving the light-shielding plate so that the light passing through the light-transmitting slit irradiates the second area, and the second area is not completely the same as the first area.

[0056] Specifically, by moving the wafer or the light shield, the area irradiated by the light-transmitting slit is changed to achieve etching of different areas.

[0057] Optionally, the second area at least partially covers the thin film 11.

[0058] Specifically, the second area at least partially covers the thin film 11, that is, the second area covers part or all of the thin film 11. The light transmitted through the light-transmitting slit 21 irradiates the thin film 11 and does not irradiate the area on the first surface 101 of the wafer 10 that does not need to be etched. For example, it does not irradiate other areas on the first surface 101 of the wafer 10 except the thin film 11.

[0059] When the size of the thin film 11 is large, for example, when the size of the thin film 11 is long, if the size of the light-transmitting slit 21 is small, the wafer 10 or the light shield 20 can be moved to make the light transmitted through the light-transmitting slit 21 irradiate the second area. After two or more moves, the second area irradiated each time is not completely the same as the first area irradiated last time, so as to complete the irradiation of different areas of the thin film 11, complete the etching of different areas of the thin film 11, until the thin film 11 is removed or the entire thin film 11 is thinned.

[0060] In the embodiment of the present invention, by moving the light shield 20 or the wafer 10, all areas of the thin film can be accurately removed through a small light-transmitting slit 21, without separately setting different light shields for thin films 11 of different sizes, thus reducing the process cost. And using a smaller light-transmitting slit 21 can more accurately control the irradiation area of the light transmitted by the light source, so as to more accurately etch the thin film 11.

[0061] Optionally, the thin film is an annular thin film;

[0062] Moving the wafer or the light shield to make the light transmitted through the light-transmitting slit irradiate the second area includes:

[0063] Rotating the wafer or the light shield to make the light transmitted through the light-transmitting slit irradiate the second area.

[0064] Specifically, Figure 3 is a schematic diagram of a thin film, refer to Figure 2 and 3 , when epitaxially growing a thin film on the second surface of the wafer 10, generally an annular thin film 11 will be grown on the first surface 101 of the wafer 10. It can be set that the light transmitted through the light-transmitting slit 21 irradiates a section of the area in the circumferential direction of the thin film 11, and by rotating the wafer 10 or the light shield 20, the light transmitted through the light-transmitting slit 21 irradiates different areas of the thin film 11 in turn.

[0065] In the embodiment of the present invention, by rotating the light shielding plate 20 or the wafer 10, a smaller light-transmitting slit 21 can be used to precisely remove the thin film 11 in a fixed-point area, so as to precisely remove or thin the entire annular thin film.

[0066] Based on the above embodiment, this embodiment provides another method for removing the thin film on the wafer surface. Figure 4 It is a flowchart of another wafer surface treatment method provided by the embodiment of the present invention. Refer to Figure 4 , the wafer surface treatment method includes the following steps:

[0067] S110: Set the light shielding plate provided with the light-transmitting slit on one side of the first surface of the wafer.

[0068] S120: Use the photoelectrochemical etching process to remove the thin film on the first surface of the wafer, or use the photoelectrochemical etching process to thin the thin film on the first surface, so that the height difference between any position on the side of the thin film away from the wafer and the first surface is less than a preset value; wherein, the light shielding plate is used to block the light emitted by the light source in the photoelectrochemical etching process, so that the light emitted by the light source passes through the light-transmitting slit and irradiates the first area, and the first area at least partially covers the thin film on the first surface of the wafer.

[0069] S130: Perform chemical mechanical polishing treatment on the first surface of the wafer.

[0070] Specifically, if there is residual oxide on the first surface of the wafer after etching the thin film by the photoelectrochemical etching process, or after thinning the thin film, the first surface of the wafer can be subjected to chemical mechanical polishing treatment to remove the oxide on the first surface of the wafer or the thin film left after thinning. Since the thickness of the residual oxide is relatively thin or the height difference between any position on the side of the thin film away from the wafer and the first surface is less than the preset value, when performing chemical mechanical polishing treatment on the first surface of the wafer, the influence on other areas of the first surface of the wafer is small or negligible. Therefore, removing the residual oxide by chemical mechanical polishing can ensure the accuracy of the subsequent lithography process.

[0071] Optionally, using the photoelectrochemical etching process to remove the thin film on the first surface of the wafer, or using the photoelectrochemical etching process to thin the thin film on the first surface of the wafer, so that the height difference between any position on the side of the thin film away from the wafer and the first surface is less than a preset value, includes:

[0072] Immerse the wafer and the thin film in the etching solution, or spray the etching solution onto the thin film on the first surface of the wafer through a nozzle.

[0073] Specifically, Figure 5 It is a process diagram of another photoelectrochemical etching provided by the embodiment of the present invention. Refer to Figure 2 and5 The wafer 10 can be placed in the etching tank 30, and the first surface 101 of the wafer 10 faces the notch of the etching tank 30 and is disposed opposite to the light shielding plate 20. The etching solution 40 is used to dissolve the oxides generated during the photoelectrochemical etching process.

[0074] Reference Figure 2 The etching solution 40 can be placed in the etching tank 30, and the entire wafer 10 and the thin film 11 are immersed in the etching solution 40, so that the etching solution 40 can preferably remove the oxides generated in the photoelectrochemical etching process.

[0075] Reference Figure 5 Alternatively, the wafer 10 may not be immersed in the etching solution, and the etching solution is sprayed onto the thin film 11 by using the nozzle 50, so that the etching solution can preferably remove the oxides generated in the photoelectrochemical etching process. In addition, the nozzle 50 can be moved so that the nozzle 50 can spray the etching solution on the thin film 11 in each region.

[0076] Optionally, before removing the thin film on the first surface of the wafer by using the photoelectrochemical etching process, or thinning the thin film on the first surface of the wafer by using the photoelectrochemical etching process until the height difference between any position on the side of the thin film away from the wafer and the first surface is less than a preset value, further comprising:

[0077] A first electrode is disposed on the first surface of the wafer;

[0078] Removing the thin film on the first surface of the wafer by using the photoelectrochemical etching process, or thinning the thin film on the first surface of the wafer by using the photoelectrochemical etching process until the height difference between any position on the side of the thin film away from the wafer and the first surface is less than a preset value, including:

[0079] A first potential signal is input to the first electrode, and a second potential signal is input to the second surface of the wafer; wherein, the first potential signal is less than the second potential signal.

[0080] Specifically, reference Figure 2 And Figure 5 The first electrode 60 can be formed on the first surface 101 of the wafer 10 by using photolithography and etching processes. The material of the first electrode 60 includes platinum, gold, glassy carbon or ruthenium titanium, etc. The wafer 10 can be used as the anode and the first electrode 60 can be used as the cathode. During the etching process, the light emitted by the light source irradiates the thin film 11 on the first surface 101 of the wafer 10, exciting electron-hole pairs. The photo-generated holes are pushed to the surface of the thin film 11 due to the band bending at the semiconductor (thin film 11) / electrolyte interface, oxidizing the thin film 11, and the generated oxides are dissolved by the etching solution 40. The photo-generated electrons move to the cathode and are consumed by the oxidant in the solution to complete the etching reaction process.

[0081] A second potential signal can be transmitted to the wafer 10 through the electrode lead 70. In addition, a reference electrode 80 can be provided, and the material of the reference electrode 80 can include graphite or a saturated calomel electrode, etc.

[0082] In an embodiment of the present invention, by providing a first electrode 60 on the first surface of the wafer 10, the first electrode 60 receives a first potential signal, the first electrode 60 serves as a cathode, the wafer 10 receives a second potential signal, and the wafer 10 serves as an anode, so that the thin film 11 can be quickly back-oxidized and dissolved, improving the etching rate.

[0083] Optionally, when using a photoelectrochemical etching process to remove the thin film on the first surface of the wafer, or when using a photoelectrochemical etching process to thin the thin film on the first surface of the wafer, after the height difference between any position on the side of the thin film away from the wafer and the first surface is less than a preset value, it further includes:

[0084] Removing the first electrode.

[0085] Specifically, processes such as wet etching or dry etching can be used to remove the first electrode.

[0086] Optionally, removing the first electrode includes:

[0087] Removing the first electrode by wet etching.

[0088] Specifically, an etching solution that can react with the first electrode but does not damage the wafer can be used to etch the first electrode, thereby removing the first electrode on the wafer surface.

[0089] Optionally, the material used for the first electrode includes at least one of platinum, gold, glassy carbon, and ruthenium titanium.

[0090] Specifically, the above materials all have good electrical conductivity and are relatively easy to fabricate and remove. Using the above materials for the first electrode can reduce the fabrication process difficulty and removal process difficulty of the first electrode.

[0091] Optionally, the material of the wafer includes silicon, gallium arsenide, silicon carbide, gallium nitride, or diamond;

[0092] The light source includes an ultraviolet light source;

[0093] The material of the light shield includes polyurethane.

[0094] Specifically, when epitaxial growth is carried out on wafers of silicon, gallium arsenide, silicon carbide, gallium nitride, and diamond, thin films are likely to be generated on the first surface of the wafers, and the thin films of the materials can be preferably removed by photoelectrochemical etching.

[0095] The ultraviolet light source has a relatively high photon energy. When the thin film is irradiated with the ultraviolet light source, the etching rate can be increased. The ultraviolet light source can be a high-pressure mercury lamp, etc.

[0096] Polyurethane materials have good light-shielding properties and are relatively easy to manufacture. Using polyurethane for the light-shielding plate can improve the light-shielding property and reduce the manufacturing cost. It should be noted that other opaque materials can also be used for the light-shielding plate, and the specific implementation of this embodiment is not specifically limited.

[0097] Optionally, the etching solution includes at least one of hydrofluoric acid, potassium hydroxide, sulfuric acid, nitric acid, potassium persulfate, and potassium hydrogen persulfate complex salt.

[0098] Specifically, hydrofluoric acid, potassium hydroxide, sulfuric acid, nitric acid, potassium persulfate, and potassium hydrogen persulfate complex salt can all dissolve oxides such as silicon oxide well. Using the above etching solution can better dissolve oxides and improve the etching speed.

[0099] The above specific implementation manners do not constitute a limitation on the protection scope of the present invention. Those skilled in the art should understand that various modifications, combinations, sub-combinations, and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A method for wafer surface treatment, characterized in that, Including: A light-shielding plate provided with a light-transmitting slit is disposed on one side of the first surface of the wafer; The film on the first surface of the wafer is removed by a photoelectrochemical etching process, or the film on the first surface of the wafer is thinned by a photoelectrochemical etching process, so that the height difference between any position on the side of the film away from the wafer and the first surface is less than a preset value; Wherein, the first surface of the wafer and the second surface of the wafer are oppositely arranged, and the second surface of the wafer is the surface where the epitaxial layer of the wafer is provided; the light-shielding plate is used to block the light emitted by the light source in the photoelectrochemical etching process, so that the light emitted by the light source passes through the light-transmitting slit and irradiates on the first region, and at least part of the first region covers the film on the first surface; the area of the film is smaller than the area of the first surface of the wafer; After the film on the first surface of the wafer is removed by a photoelectrochemical etching process, or the film on the first surface of the wafer is thinned by a photoelectrochemical etching process, so that the height difference between any position on the side of the film away from the wafer and the first surface is less than a preset value, it further includes: Performing chemical mechanical polishing treatment on the first surface of the wafer.

2. The wafer surface treatment method according to claim 1, wherein Removing the film on the first surface of the wafer by a photoelectrochemical etching process, or thinning the film on the first surface of the wafer by a photoelectrochemical etching process, so that the height difference between any position on the side of the film away from the wafer and the first surface is less than a preset value, including: Moving the wafer or moving the light-shielding plate so that the light passing through the light-transmitting slit irradiates on a second region, and the second region is not completely the same as the first region.

3. The wafer surface treatment method according to claim 2, wherein At least part of the second region covers the film.

4. The wafer surface treatment method according to claim 2, characterized in that, The film is an annular film; Moving the wafer or moving the light-shielding plate so that the light passing through the light-transmitting slit irradiates on a second region includes: Rotating the wafer or rotating the light-shielding plate so that the light passing through the light-transmitting slit irradiates on the second region.

5. The wafer surface treatment method according to claim 1, wherein Removing the film on the first surface of the wafer by a photoelectrochemical etching process, or thinning the film on the first surface of the wafer by a photoelectrochemical etching process, so that the height difference between any position on the side of the film away from the wafer and the first surface is less than a preset value, including: Immersing the wafer and the film in an etching solution, or spraying the etching solution on the film on the first surface of the wafer through a nozzle.

6. The wafer surface treatment method according to claim 1, characterized in that, Before the film on the first surface of the wafer is removed by a photoelectrochemical etching process, or the film on the first surface of the wafer is thinned by a photoelectrochemical etching process, so that the height difference between any position on the side of the film away from the wafer and the first surface is less than a preset value, it further includes: Setting a first electrode on the first surface of the wafer; Removing the film on the first surface of the wafer by a photoelectrochemical etching process, or thinning the film on the first surface of the wafer by a photoelectrochemical etching process, so that the height difference between any position on the side of the film away from the wafer and the first surface is less than a preset value, including: Input a first potential signal to the first electrode and input a second potential signal to the second surface of the wafer; wherein, the first potential signal is less than the second potential signal; After removing the thin film on the first surface of the wafer by using an optoelectrochemical etching process, or thinning the thin film on the first surface of the wafer by using an optoelectrochemical etching process so that the height difference between any position on the side of the thin film away from the wafer and the first surface is less than a preset value, it further includes: Remove the first electrode.

7. The wafer surface treatment method according to claim 6, wherein Removing the first electrode includes: Remove the first electrode by wet etching; The material used for the first electrode includes at least one of platinum, gold, glassy carbon, and ruthenium titanium.

8. The method for processing the wafer surface according to claim 1, wherein The material of the wafer includes silicon, gallium arsenide, silicon carbide, gallium nitride, or diamond; The light source includes an ultraviolet light source; The material of the light shield includes polyurethane.

9. The method for processing the wafer surface according to claim 5, wherein: The etching solution includes at least one of hydrofluoric acid, potassium hydroxide, sulfuric acid, nitric acid, potassium persulfate, and potassium hydrogen persulfate complex salt.

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