Substrate recycling method, regenerated photomask base plate, and photomask manufacturing method

Abstract

The present invention provides a substrate recycling method, a regenerated photomask base plate, and a photomask manufacturing method. The substrate recycling method is used for performing substrate recycling on a scrapped photomask, wherein the photomask comprises a substrate and a mask structure formed on the substrate. The substrate recycling method comprises: providing a plasma etching system; setting the plasma etching system to be in a plasma-chemical etching mode, so as to remove the mask structure and avoid damaging the surface of the substrate; and setting the plasma etching system to be in a plasma superpolishing mode, so as to polish the surface of the substrate. The technical solution of the present invention can reduce the costs and avoid damage to the surfaces of substrates to the maximum extent, such that the quality of photomasks is improved, and substrates can be recycled multiple times for regeneration.

Description

Substrate recycling method, regenerated photomask base plate, and photomask plate manufacturing method Technical Field

[0001] The present invention relates to the technical field of integrated circuit manufacturing, and in particular to a substrate recovery method, a regenerated photomask base plate and a photomask manufacturing method. Background Art

[0002] Due to the high cost of the substrate used in photomasks (typically high-purity synthetic quartz), discarded photomask substrates are often recycled to reduce costs. Currently, substrate recycling methods include: first, removing the pattern material (typically metal and metal oxide) from the substrate using processes such as wet etching, laser ablation, or plasma etching; then, using chemical mechanical polishing to remove the damaged surface layer of the substrate; then, using super polishing to polish the substrate surface to an optical grade to achieve a smooth surface; and finally, wet cleaning the substrate surface.

[0003] Among them, wet etching is highly selective to the pattern material on the substrate, the surface uniformity of the substrate after etching is good, and it has the advantages of low induced diffusion of the substrate and low cost. However, it is necessary to provide a wet etching workbench and consume a large amount of acid solution; laser ablation adopts point-by-point ablation, which leads to rough and uneven defects on the substrate surface after ablation, and high induced diffusion of the substrate; plasma etching is highly selective to the substrate, the surface uniformity of the substrate after etching is good, and the presence of DC bias voltage makes the etching rate high, but plasma bombardment can cause damage to the substrate surface, and the presence of plasma and the high energy of ions during etching lead to high induced diffusion of the substrate, and the cost of the plasma etching system is high; chemical mechanical polishing makes the substrate surface uniform, but has poor selectivity to the substrate, a lot of substrate material loss, high cost, and requires grinding fluid as a consumable; super polishing adopts a small aperture, mainly point-by-point removal, resulting in slow removal speed, and the cost of the super polishing system is high.

[0004] The aforementioned substrate recycling methods are complex, require multiple different processes, are costly, and can cause significant damage to the substrate surface, leading to significant loss of substrate material. Therefore, improvements are needed to reduce costs, avoid surface damage, and enable multiple recycling and reuse of substrates.

[0005] Summary of the Invention

[0006] The purpose of the present invention is to provide a substrate recycling method, a regenerated photomask base plate and a photomask manufacturing method, which can reduce costs and avoid damage to the substrate surface to the greatest extent, so that the quality of the photomask is improved, and the substrate can be recycled and reused multiple times.

[0007] To achieve the above-mentioned object, the present invention provides a substrate recycling method for recycling a scrapped photomask, wherein the photomask includes a substrate and a mask structure formed on the substrate. The substrate recycling method comprises:

[0008] Providing a plasma etching system;

[0009] Setting the plasma etching system to a plasma chemical etching mode to remove the mask structure and avoid damaging the substrate surface;

[0010] The plasma etching system is set to a plasma super polishing mode to polish the surface of the substrate.

[0011] Optionally, the plasma etching system includes:

[0012] A remote plasma generator is used to emit plasma toward the surface of the photomask.

[0013] Optionally, the plasma etching system further includes:

[0014] an anode, disposed above the photomask;

[0015] a chuck, used for carrying the photomask;

[0016] A reaction chamber is provided, wherein the remote plasma generator is arranged outside the reaction chamber and is in communication with the reaction chamber, and the anode and the chuck are both arranged in the reaction chamber.

[0017] Optionally, the plasma etching system further includes:

[0018] A DC power supply is connected to the anode and the chuck to generate a DC bias voltage between the anode and the chuck.

[0019] Optionally, the plasma etching system further includes:

[0020] The coil is arranged outside the reaction chamber and is used to generate a magnetic field parallel to the surface of the substrate.

[0021] Optionally, the plasma etching system includes one reaction chamber, and the plasma chemical etching mode and the plasma super polishing mode share the reaction chamber; or, the plasma etching system includes at least two reaction chambers, and the plasma chemical etching mode and the plasma super polishing mode use different reaction chambers.

[0022] Optionally, when the plasma etching system is set to the plasma chemical etching mode, the remote plasma generator emits to the surface of the photomask: highly chemically active plasma generated by ionizing fluorine-containing gas and / or chlorine-containing gas; when the plasma etching system is set to the plasma super polishing mode, the remote plasma generator emits to the surface of the photomask: chemically inactive plasma generated by ionizing inert gas.

[0023] Optionally, when the plasma etching system is set to the plasma chemical etching mode: the gas pressure in the reaction chamber is 100 Torr~5atm; the DC power supply is in the off state, so that the DC bias is not generated; the temperature of the chuck is 25℃~200℃; no current is connected to the coil, so that the magnetic field is not generated.

[0024] Optionally, when the plasma etching system is set to the plasma super polishing mode: the gas pressure in the reaction chamber is <100Torr; the DC power supply is in the on state, so that the generated DC bias voltage is 0V~500V; the temperature of the chuck is 25℃~200℃; and current is connected to the coil, so that the generated magnetic field is 0T~5T.

[0025] Optionally, the front side and / or the back side of the substrate is polished.

[0026] The present invention also provides a method for manufacturing a regenerated photomask base, comprising:

[0027] Providing a scrapped photomask, the photomask comprising a substrate and a mask structure formed on the substrate;

[0028] Recycling the substrate of the photomask using the substrate recycling method to obtain a regenerated substrate;

[0029] forming a light shielding layer on the regenerated substrate;

[0030] A photoresist layer is formed on the light shielding layer.

[0031] Optionally, before forming the light shielding layer on the regenerated substrate, the method for manufacturing the regenerated photomask blank further comprises:

[0032] A phase shift layer is formed on the regenerated substrate, and the light shielding layer is located on the phase shift layer.

[0033] Optionally, before forming the phase shift layer on the regenerated substrate, the method for manufacturing the regenerated photomask blank further comprises:

[0034] A spin-on carbon layer is formed on the front side and / or the back side of the regenerated substrate.

[0035] The present invention also provides a method for manufacturing a photomask, comprising:

[0036] Forming a photomask base using the regenerated photomask base manufacturing method;

[0037] Patterning the photoresist layer so that the photoresist layer is formed into a patterned photoresist layer;

[0038] Using the patterned photoresist layer as a mask, etching the light shielding layer to form a patterned light shielding layer on the substrate;

[0039] The patterned photoresist layer is removed.

[0040] Optionally, a phase shift layer is formed between the regenerated substrate and the light shielding layer, and after etching the light shielding layer using the patterned photoresist layer as a mask, the phase shift layer is also etched.

[0041] Compared with the prior art, the technical solution of the present invention has the following beneficial effects:

[0042] 1. The substrate recycling method of the present invention realizes the recycling of substrates in used or discarded photomasks by setting a plasma etching system to a plasma chemical etching mode to remove the mask structure and avoid damaging the substrate surface; and setting the plasma etching system to a plasma super polishing mode to polish the substrate surface, thereby greatly simplifying the process steps and process types, thereby significantly reducing costs, and avoiding damage to the substrate surface to the greatest extent.

[0043] 2. The manufacturing method of the regenerated photomask base of the present invention adopts the substrate recycling method to recycle the substrate in the scrapped photomask base; forms a light-shielding layer on the regenerated substrate; and forms a photoresist layer on the light-shielding layer, so that the cost of manufacturing the non-patterned photomask base is reduced, the quality of the photomask base is improved, and the non-patterned mask base can be recycled and reused multiple times.

[0044] 3. The method for manufacturing a photomask of the present invention adopts the method for manufacturing a regenerated photomask base to form a photomask base; patterns the photoresist layer so that the photoresist layer is formed into a patterned photoresist layer; uses the patterned photoresist layer as a mask to etch the light-shielding layer so as to form a patterned light-shielding layer on the substrate; and removes the patterned photoresist layer, thereby reducing the cost of manufacturing the photomask and improving the quality of the photomask, and allowing the patterned photomask to be recycled and reused multiple times. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] FIG1 is a schematic diagram of a plasma etching system according to an embodiment of the present invention;

[0046] FIG2 is a flow chart of a substrate recovery method according to an embodiment of the present invention;

[0047] 3 is a schematic structural diagram of a photomask according to an embodiment of the present invention;

[0048] 4 is a schematic structural diagram of a substrate after removing the mask structure according to an embodiment of the present invention;

[0049] FIG5 is a schematic structural diagram of a polished substrate according to an embodiment of the present invention.

[0050] 1 to 5 , the reference numerals are as follows: 10 - photomask; 11 - substrate; 111 - atom; 12 - mask structure; 21 - reaction chamber; 22 - chuck; 23 - remote plasma generator; 231 - pipeline; 24 - anode; 25 - inlet; 26 - outlet. DETAILED DESCRIPTION

[0051] In the following description, a large number of specific details are given in order to provide a more thorough understanding of the present invention. However, it will be apparent to those skilled in the art that the present invention can be implemented without one or more of these details. In other examples, in order to avoid confusion with the present invention, some technical features known in the art are not described. It should be understood that the present invention can be implemented in different forms and should not be construed as being limited to the embodiments set forth herein. On the contrary, providing these embodiments will make the disclosure thorough and complete and will fully convey the scope of the present invention to those skilled in the art. In the accompanying drawings, the sizes and relative sizes of layers and regions may be exaggerated for clarity. The same reference numerals represent the same elements throughout.

[0052] It should be understood that when an element or layer is referred to as "on..." other elements or layers, it can be directly on, adjacent to, connected to or coupled to other elements or layers, or there can be intervening elements or layers. On the contrary, when an element is referred to as "directly on..." other elements or layers, there are no intervening elements or layers. It should be understood that although the terms first, second, third, etc. can be used to describe various elements, components, areas, layers, parts and / or processes, these elements, components, areas, layers, parts and / or processes should not be limited by these terms. These terms are only used to distinguish one element, component, area, layer, part and / or process from another element, component, area, layer, part and / or process. Therefore, without departing from the teachings of the present invention, the first element, component, area, layer, part and / or process discussed below can be expressed as a second element, component, area, layer, part and / or process.

[0053] Spatially relative terms such as "under," "beneath," "beneath," "under," "above," "above," "on the top," "on the bottom," "front," "back," etc., may be used herein for convenience of description to describe the relationship of one element or feature shown in the figures to other elements or features. It should be understood that the spatially relative terms are intended to include different orientations of the device in use and operation in addition to the orientations shown in the figures. For example, if the device in the drawings is turned over, then the element or feature described as "under the other elements" or "under it" or "beneath it" or "on the bottom" or "on the back" will be oriented as "on" or "top" or "front" of the other elements or features. Thus, the exemplary terms "under," "under," and "on the back" may include both the top and bottom orientations. The device may be oriented otherwise (rotated 90 degrees or in other orientations) and the spatial descriptors used herein are interpreted accordingly.

[0054] The purpose of the terms used herein is only to describe specific embodiments and is not intended to limit the present invention. When used herein, the singular forms "a", "an", and "the" are intended to include the plural forms, unless the context clearly indicates otherwise. It should also be understood that the terms "comprising" and / or "comprising", when used in this specification, determine the presence of the features, integers, steps, operations, elements and / or parts, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, parts and / or groups. When used herein, the term "and / or" includes any and all combinations of the relevant listed items.

[0055] An embodiment of the present invention provides a substrate recycling method for recycling a scrapped photomask, wherein the photomask includes a substrate and a mask structure formed on the substrate. Referring to FIG. 2 , it can be seen from FIG. 2 that the substrate recycling method includes:

[0056] Step S1, providing a plasma etching system;

[0057] Step S2, setting the plasma etching system to a plasma chemical etching mode to remove the mask structure and avoid damaging the substrate surface;

[0058] Step S3: setting the plasma etching system to a plasma super polishing mode to polish the surface of the substrate.

[0059] The substrate recovery method provided by this embodiment will be described in detail below with reference to FIG1 and FIG3 to FIG5 . FIG3 to FIG5 are schematic longitudinal cross-sectional views.

[0060] According to step S1 , a plasma etching system is provided.

[0061] As shown in FIG3 , the photomask 10 may include a substrate 11 and a mask structure 12 formed on the substrate 11. The mask structure 12 may be an unpatterned structure, in which case the mask structure 12 covers the entire surface of the substrate 11; or the mask structure 12 may be a patterned structure, in which case the mask structure 12 covers a portion of the surface of the substrate 11 and exposes a portion of the surface of the substrate 11.

[0062] The mask structure 12 may include only a light-shielding layer (not shown), or the mask structure 12 may include a phase-shift layer (not shown) and a light-shielding layer formed on the phase-shift layer; or the mask structure 12 may include a phase-shift layer, a light-shielding layer, and a photoresist layer from bottom to top.

[0063] It should be noted that the substrate 11 may have a flat surface; alternatively, the substrate 11 may have an uneven surface, for example, with protrusions at some locations on the surface of the substrate 11. Figures 3 to 5 schematically illustrate atoms 111 on the surface of the substrate 11 to illustrate the flatness of the surface of the substrate 11. Position A1 on the surface of the substrate 11 has more atoms 111 than other positions, meaning that position A1 on the surface of the substrate 11 has a protrusion relative to other positions.

[0064] The material of the substrate 11 may include at least one of quartz, borosilicate, aluminum silicate, silicon and silicon carbide, the material of the light shielding layer may include at least one of Cr, CrO2, CrN, etc., and the material of the phase shift layer may include MoSi x O y N z .

[0065] Since the cost of the substrate 11 in the photomask 10 is relatively high, in order to reduce the cost, the used or discarded substrate 11 in the photomask 10 is usually recycled. In this embodiment, the plasma etching system is used to recycle the substrate 11 in the photomask 10.

[0066] The plasma etching system may include a remote plasma generator 23 , and the remote plasma generator 23 is configured to emit high-density, low-energy plasma toward the surface of the photomask 10 .

[0067] The plasma etching system may further include:

[0068] an anode 24 disposed above the photomask 10;

[0069] A chuck 22 for carrying the photomask 10 , wherein the chuck 22 can serve as a cathode;

[0070] At least one reaction chamber 21 , the remote plasma generator 23 is disposed outside the reaction chamber 21 , and the anode 24 and the chuck 22 are both disposed in the reaction chamber 21 .

[0071] The remote plasma generator 23 can be connected to the reaction chamber 21 through a pipe 231, and the pipe 231 extends from the outside of the reaction chamber 21 to the inside of the reaction chamber 21, so that the plasma emitted by the remote plasma generator 23 can be remotely transported to the reaction chamber 21 through the pipe 231, and then emitted to the surface of the photomask 10.

[0072] The remote plasma generator 23 may be an existing remote plasma generator. In one embodiment, the remote plasma generator 23 may include components such as a radio frequency power supply, an anode, and a cathode for generating plasma.

[0073] Furthermore, since the remote plasma generator 23 remotely transports plasma from outside the reaction chamber 21 into the reaction chamber 21 , the ions in the plasma have low energy and high density, thereby causing minimal damage to the surface of the substrate 11 in the photomask 10 caused by the plasma.

[0074] The side wall of the reaction chamber 21 may be provided with an inlet 25 and an outlet 26. An inert gas is introduced into the reaction chamber 21 through the inlet 25 to adjust the gas pressure and gas atmosphere in the reaction chamber 21. The reaction chamber 21 is connected to a vacuum pump through the outlet 26 so that the gas in the reaction chamber 21 and the gas products generated by the reaction can be extracted by the vacuum pump.

[0075] Optionally, the plasma etching system may further include a DC power supply (not shown), which is connected to the anode 24 and the chuck 22 to generate a voltage difference between the anode 24 and the chuck 22, thereby generating a DC bias.

[0076] Optionally, the plasma etching system may further include at least one coil (not shown) disposed on the periphery of the reaction chamber 21, and the coil is used to generate a magnetic field parallel to the surface of the photomask 10 (i.e., parallel to the surface of the substrate 11) so as to deflect the plasma perpendicular to the surface of the substrate 11 in a direction parallel to the surface of the substrate 11 under the action of the magnetic field, and the direction of the deflection component is perpendicular to the direction of the magnetic field.

[0077] It should be noted that the plasma etching system is not limited to the above-mentioned components, and may also include other components as needed, for example, a heating component for heating the chuck 22; and a controller for controlling the use of each component.

[0078] According to step S2 , the plasma etching system is set to a plasma chemical etching mode to remove the material of the mask structure 12 in the photomask 10 while avoiding damaging the surface of the substrate 11 .

[0079] When the plasma etching system is set to the plasma chemical etching mode, the remote plasma generator 23 emits a highly chemically active plasma generated by ionizing a fluorine-containing gas (e.g., CF4, SF6, etc.) and / or a chlorine-containing gas (e.g., Cl2, BCl3, etc.) toward the surface of the photomask 10. It should be noted that the highly chemically active plasma is not limited to the highly chemically active plasma generated by ionizing a fluorine-containing gas (e.g., CF4, SF6, etc.) and / or a chlorine-containing gas (e.g., Cl2, BCl3, etc.), and can also be a highly chemically active plasma generated by ionizing an oxygen-containing gas, etc. The type of gas is selected based on the material of the mask structure 12 to be removed.

[0080] The principle of removing the mask structure 12 from the photomask 10 is as follows: the plasma generated by ionizing the fluorine-containing gas and / or the chlorine-containing gas is highly chemically active. Upon contact with the mask structure 12, the ions in the plasma combine with the material of the mask structure 12 to form gaseous products. The gaseous products are then extracted from the reaction chamber 21 by a vacuum pump, completing the removal of the mask structure 12. FIG. 4 is a schematic diagram of the surface of the substrate 11 after the mask structure 12 has been removed.

[0081] When the plasma etching system is set to the plasma chemical etching mode, the gas pressure in the reaction chamber 21 is optionally set to 100 Torr to 5 atm; the DC power supply is turned off, so that the DC bias is not generated; the temperature of the chuck 22 is set to 25°C to 200°C; and no current is connected to the coil, so that the magnetic field is not generated. It should be noted that the plasma chemical etching mode is not limited to the above parameters, and other parameters can be added according to the etching effect requirements.

[0082] Among them, when the DC bias is not generated, the plasma can be avoided from being accelerated, so that the plasma can maintain a relatively low speed to reach the surface of the photomask 10, and the mask structure 12 is mainly removed by the chemical reaction between the plasma and the material of the mask structure 12, thereby preventing the plasma from hitting the surface of the substrate 11 exposed by the mask structure 12 at an excessively fast speed and causing damage to the surface of the substrate 11.

[0083] Furthermore, since the pressure in the reaction chamber 21 is relatively high, the movement speed of the plasma can be reduced, thereby further reducing the damage to the surface of the substrate 11 caused by the plasma impacting the surface of the substrate 11 .

[0084] Furthermore, by heating the chuck 22 , the chemical reaction rate between the plasma and the material of the mask structure 12 can be increased, thereby increasing the removal rate of the material of the mask structure 12 .

[0085] Since the mask structure 12 is removed mainly by the chemical reaction between the plasma and the material of the mask structure 12, by selecting the appropriate type of fluorine-containing gas and / or the chlorine-containing gas for different types of materials of the mask structure 12, the plasma can be made highly selective for the material of the mask structure 12 as compared with the material of the substrate 11, thereby enabling the mask structure 12 to be removed quickly without damaging the substrate 11, and the removal of the mask structure 12 has high uniformity and a high removal rate (for example, the removal rate can be greater than 5 nm / min).

[0086] According to step S3, the plasma etching system is set to a plasma super polishing mode to precisely polish the surface of the substrate 11. The front side and / or back side of the substrate 11 may be polished, with the front side and the back side being opposite sides.

[0087] When the plasma etching system is set to the plasma super-polishing mode, the remote plasma generator 23 emits chemically inactive plasma generated by ionizing an inert gas toward the surface of the photomask 10 (ie, toward the surface of the substrate 11 ).

[0088] The inert gas may include at least one of helium, argon, nitrogen, and the like.

[0089] The principle of polishing the surface of substrate 11 is that chemically inactive plasma generated by ionizing an inert gas moves toward the surface of substrate 11, sputtering and removing atoms 111 on the surface of substrate 11, thereby polishing the surface of substrate 11. As shown in Figure 5, after polishing the surface of substrate 11, the protruding atoms 111 at position A1 on the surface of substrate 11 are removed, thereby improving the flatness of the surface of substrate 11 and reducing the surface roughness of substrate 11.

[0090] When the plasma etching system is set to the plasma super-polishing mode, the gas pressure in the reaction chamber 21 is optionally less than 100 Torr; the DC power supply is turned on, so that the generated DC bias voltage is 0V to 500V; the temperature of the chuck 22 is 25°C to 200°C; and a current is connected to the coil, so that the generated magnetic field is 0T to 5T. It should be noted that the plasma super-polishing mode is not limited to the above parameters, and other parameters can be added according to the required polishing effect.

[0091] When the DC bias is generated, the plasma can be accelerated toward the surface of the substrate 11 in a direction perpendicular to the substrate 11, and by selecting a suitable magnitude of the DC bias, the plasma can reach the surface of the substrate 11 at a suitable speed, thereby polishing the surface of the substrate 11 (i.e., removing atoms from the protrusions on the surface of the substrate 11) while avoiding damage to the surface of the substrate 11.

[0092] Furthermore, since the gas pressure in the reaction chamber 21 is relatively low, the movement speed of the plasma can be slightly increased, thereby optimizing the polishing effect on the surface of the substrate 11 .

[0093] Furthermore, when the coil generates a magnetic field parallel to the surface of the substrate 11, the plasma in a direction perpendicular to the surface of the substrate 11 is deflected in a direction parallel to the surface of the substrate 11 under the action of the magnetic field, causing the movement direction of most of the plasma to be deflected in a direction parallel to the surface of the substrate 11. This deflects the force perpendicular to the surface of the substrate 11, polishing the surface of the substrate 11, thereby reducing the vertical impact of the plasma on the atoms on the surface of the substrate 11 and thus reducing impact damage to the surface of the substrate 11. The force parallel to the surface of the substrate 11 is mainly used to remove protrusions on the surface of the substrate 11 (i.e., stacked atoms on the protrusions), reducing the removal of material from flat areas on the surface of the substrate 11, thereby reducing damage to the surface of the substrate 11. Therefore, under the action of the magnetic field parallel to the surface of the substrate 11, the surface of the substrate 11 can be polished to a flatness in the atomic scale range, thereby significantly improving the flatness of the surface of the substrate 11 and improving the surface roughness of the substrate 11.

[0094] Optionally, when the plasma etching system includes at least four coils, each of the coils is evenly arranged on the periphery of the reaction chamber 21 and surrounds the substrate 11, and each of the coils is symmetrically arranged with respect to the central axis of the substrate 11, the at least four coils are used to generate a rotating magnetic field parallel to the surface of the substrate 11. Under the action of the rotating magnetic field, the magnetic field can be more evenly distributed in various regions close to the surface of the substrate 11, so that the plasma generates deflection components in various directions parallel to the surface of the substrate 11, and the plasma deflected by the rotating magnetic field is further evenly distributed in various regions parallel to the surface of the substrate 11, thereby improving the polishing uniformity of various regions on the surface of the substrate 11 and further improving the flatness of the polished surface of the substrate 11.

[0095] Further optionally, the number of the coils is a positive integer multiple of 4, and the coils are evenly arranged on the periphery of the reaction chamber 21 and surround the substrate 11, so that the magnetic field is more evenly distributed in various areas close to the surface of the substrate 11.

[0096] When the rotating magnetic field is generated, each of the coils is cyclically switched in sequence along the direction surrounding the substrate 11 to be connected to the current, that is, each of the coils is cyclically switched in sequence along the direction surrounding the substrate 11 to be connected to the current continuously, and only one of the coils is connected to the current at the same time; or, each of the coils is cyclically switched in sequence along the direction surrounding the substrate 11 to be connected to the current, and two of the coils symmetrically arranged with respect to the central axis of the substrate 11 are connected to the current at the same time, that is, each of the coils is cyclically switched in sequence along the direction surrounding the substrate 11 to be connected to the current continuously, and two of the coils are connected to the current at the same time.

[0097] Moreover, when the two coils symmetrically arranged relative to the central axis of the substrate 11 are connected to current at the same time, the directions of the currents connected to the two symmetrically arranged coils are opposite, so that the directions of the magnetic fields generated by the two symmetrically arranged coils are the same, thereby increasing the magnetic field strength, thereby making the surface of the substrate 11 polished more evenly.

[0098] Taking the case where there are four coils (e.g., a first coil, a second coil, a third coil, and a fourth coil) as an example, the generation of the rotating magnetic field is described as follows: the first coil, the second coil, the third coil, and the fourth coil are sequentially and evenly arranged in a clockwise direction on the periphery of the reaction chamber 21 and surround the substrate 11, the first coil and the third coil are symmetrical with respect to the central axis of the substrate 11, and the second coil and the fourth coil are symmetrical with respect to the central axis of the substrate 11; the first coil, the second coil, the third coil, and the fourth coil can be connected to current in sequence, and only one coil is connected to current at a time, that is, the first coil, the second coil, the third coil, and the fourth coil are switched to current in sequence and continuously, so that the rotating magnetic field is generated in the area near the surface of the substrate 11; alternatively, the first coil and the third coil are first connected to current in opposite directions (at this time, the second coil and the fourth coil are not connected to current), and then the second coil and the fourth coil are connected to current in opposite directions (at this time, the first coil and the third coil are not connected to current), and this cycle is repeated, so that the rotating magnetic field is generated in the area near the surface of the substrate 11.

[0099] In other embodiments, when the number of the coils is less than or equal to three, or when the number of the coils is at least four and the coils fail to switch in sequence to connect to the current, the magnetic field generated by the coils is not a rotating magnetic field. At this time, the size, current intensity and number of the coils can be increased so that the magnetic field generated by the coils can cover the entire surface of the substrate 11, thereby improving the uniformity of the surface polishing of the substrate 11; and at this time, if the two coils symmetrically arranged relative to the central axis of the substrate 11 are connected to the current at the same time, by connecting the current to the two symmetrically arranged coils in opposite directions, the magnetic fields generated by the two symmetrically arranged coils are also in the same direction, thereby increasing the magnetic field intensity, thereby making the surface polishing of the substrate 11 faster and more uniform.

[0100] Furthermore, by heating the chuck 22 , atoms of the same type as the substrate 11 at the raised portions of the surface of the substrate 11 can be more easily polished away.

[0101] Therefore, when the plasma etching system is set to the plasma super polishing mode, by controlling the gas pressure in the reaction chamber 21, the DC bias, the temperature of the chuck 22, and the size of the magnetic field and other parameters, it is possible to have a low removal rate (for example, the removal rate can be less than 5 nm / min) and low selectivity for the material on the surface of the substrate 11, thereby making the surface of the polished substrate 11 have ultra-high uniformity, ultra-high surface flatness, and surface roughness in the atomic size range.

[0102] In addition, the plasma etching system may include one reaction chamber 21, and the plasma chemical etching mode and the plasma super polishing mode share the reaction chamber 21. The switching between the plasma chemical etching mode and the plasma super polishing mode is achieved by adjusting parameters such as the gas pressure in the reaction chamber 21, the DC bias, the temperature of the chuck 22, and the magnetic field; or, the plasma etching system may include at least two reaction chambers 21, and the plasma chemical etching mode and the plasma super polishing mode use different reaction chambers 21 to avoid cross contamination caused by the two modes sharing the same reaction chamber 21.

[0103] In addition, the plasma chemical etching mode and the plasma super polishing mode may share or use different reaction chambers 21 , and the substrate 11 may be reversed by a robot to achieve chemical etching or super polishing on both sides as needed.

[0104] When the plasma chemical etching mode and the plasma super polishing mode use different reaction chambers 21, all of the reaction chambers 21 can be set on the same work platform so that after the mask structure 12 is removed, the photomask 10 can be quickly transferred to the reaction chamber 21 corresponding to the plasma super polishing mode to polish the surface of the substrate 11, thereby improving the efficiency of recovering the substrate 11; and, since the rate of removing the mask structure 12 using the plasma chemical etching mode is greater than the rate of polishing the surface of the substrate 11 using the plasma super polishing mode, the ratio of the number of the reaction chambers 21 corresponding to the plasma chemical etching mode to the number of the reaction chambers 21 corresponding to the plasma super polishing mode can be set to 1:2, thereby further improving the efficiency of recovering the substrate 11.

[0105] As can be seen from the above, the substrate recovery method of the present invention realizes the recovery of the substrate in the used or discarded photomask by setting the plasma etching system to a plasma chemical etching mode to remove the mask structure; and setting the plasma etching system to a plasma super polishing mode to polish the substrate surface. In addition, the method of recovering the substrate is reduced from the existing four steps (i.e., using a process such as wet etching, laser ablation, or plasma etching to remove the pattern material on the substrate; then, using a chemical mechanical polishing process to remove the damaged surface layer of the substrate; then, using a super polishing process to polish the substrate surface to give the substrate a smooth surface; and then, wet cleaning the substrate surface.) to the two steps of the present invention, thereby greatly simplifying the process steps. Only one plasma etching system is used to achieve substrate recovery, which greatly simplifies the process types. Therefore, the cost is significantly reduced.

[0106] Furthermore, by adjusting the parameters of the plasma etching system, switching between different modes can be achieved, thereby realizing the recycling of the substrate, and significantly reducing the difficulty of the process.

[0107] Furthermore, by precisely adjusting the parameters of the plasma chemical etching mode and the plasma super polishing mode, damage to the substrate surface can be avoided to the greatest extent, and the substrate can be recycled and reused multiple times.

[0108] An embodiment of the present invention provides a method for manufacturing a regenerated photomask blank, the method comprising:

[0109] First, a scrapped photomask is provided. The photomask includes a substrate and a mask structure formed on the substrate.

[0110] The mask structure may be an unpatterned structure, in which case the mask structure covers the entire surface of the substrate; or the mask structure may be a patterned structure, in which case the mask structure covers a portion of the surface of the substrate and exposes a portion of the surface of the substrate.

[0111] The mask structure may include only a light shielding layer, or the mask structure may include a phase shift layer and a light shielding layer formed on the phase shift layer; or the mask structure may include a phase shift layer, a light shielding layer and a photoresist layer from bottom to top.

[0112] The material of the substrate may include at least one of quartz, borosilicate, aluminum silicate, silicon and silicon carbide.

[0113] Taking quartz as an example, the steps of forming the substrate may include: first, providing a base, which may be a quartz ingot; then, synthesizing quartz on the base using a chemical vapor deposition process, wherein volatile liquid SiCl4, driven by a carrier gas, enters H2 / O2 combustion gas to react with water vapor to generate amorphous silicon dioxide, which is then deposited on a high-temperature rotating target and eventually melted to form high-purity synthetic quartz; then, cutting the synthetic quartz according to required specifications, melting it, and injecting it into a mold to obtain quartz of the required shape; then, using a chemical mechanical polishing process to remove the damaged surface layer of the quartz; then, using a super polishing process to polish the quartz surface to make the quartz have a smooth surface; and then, wet cleaning the quartz surface to obtain the quartz substrate.

[0114] Then, the substrate recycling method is used to recycle the scrapped photomask substrate to obtain a regenerated substrate.

[0115] The substrate recovery method is described above and will not be repeated here.

[0116] Then, a light shielding layer is formed on the regenerated substrate.

[0117] The light shielding layer may be formed on the regenerated substrate by a sputtering deposition process.

[0118] The material of the light shielding layer may include at least one of Cr, CrO2, CrN, etc.

[0119] Then, a photoresist layer is formed on the light shielding layer to regenerate a photomask base plate without patterns.

[0120] The photoresist layer may be formed on the light shielding layer by a spin coating process.

[0121] Optionally, before forming the light-shielding layer on the regenerated substrate, the method for manufacturing the regenerated photomask blank may further include: forming a phase-shift layer on the regenerated substrate, wherein the light-shielding layer is located on the phase-shift layer.

[0122] The phase shift layer may be formed on the regenerated substrate by a sputtering deposition process.

[0123] The material of the phase shift layer may include MoSi x O y N z .

[0124] Optionally, before forming the phase shift layer on the regenerated substrate, the method for manufacturing the photomask base may further include: forming a spin-on carbon layer on the front and / or back side of the regenerated substrate to bury defects on the surface of the substrate and provide a flat process surface.

[0125] The step of forming the spin-coated carbon layer on the regenerated substrate may include: first, spin-coating a carbon material on the recycled regenerated substrate, and the thickness of the spin-coated carbon material may be selected to be 5nm to 20nm; then, baking the carbon material to form the spin-coated carbon layer, and the baking temperature may be selected to be 100℃ to 250℃.

[0126] Since the regenerated substrate is recovered by adopting the substrate recovery method, after adopting the plasma chemical etching mode to remove the mask structure, it is only necessary to adjust the parameters of the plasma etching system to switch to the plasma super polishing mode to polish the substrate surface, thereby realizing the recovery of the substrate, which significantly reduces the process difficulty; and the method of recovering the substrate is reduced from the existing four steps (i.e., adopting wet etching, laser ablation or plasma etching processes to remove the pattern material on the substrate; and then re-performing the last three steps of the above-mentioned steps of forming the substrate) to the two steps of the present invention, thereby greatly simplifying the process steps, and only using the plasma etching system to realize the recovery of the substrate, which greatly simplifies the process types, thereby significantly reducing the cost.

[0127] Furthermore, by precisely adjusting the parameters of the plasma chemical etching mode and the plasma super polishing mode, damage to the substrate surface can be avoided to the greatest extent, thereby improving the quality of the regenerated photomask blank.

[0128] An embodiment of the present invention provides a method for manufacturing a photomask, the method comprising:

[0129] First, a photomask blank without patterns is formed by adopting the manufacturing method of the regenerated photomask blank.

[0130] The manufacturing method of the regenerated photomask base is described above and will not be repeated here.

[0131] Then, the photoresist layer is patterned to form a patterned photoresist layer.

[0132] The photoresist layer may be exposed and developed by laser or electron beam to form a patterned photoresist layer.

[0133] Then, the light shielding layer is etched using the patterned photoresist layer as a mask to form a patterned light shielding layer on the substrate.

[0134] Wherein, a dry etching process or a wet etching process may be adopted; the pattern of the patterned light-shielding layer may be the same as or different from the pattern of the light-shielding layer in the patterned mask structure before the substrate is recycled.

[0135] Then, the patterned photoresist layer is removed to obtain a photomask with a pattern.

[0136] The patterned photoresist layer may be removed by an ashing process.

[0137] When a phase-shift layer is formed between the regenerated substrate and the light-shielding layer, after etching the light-shielding layer using the patterned photoresist layer as a mask, the phase-shift layer is also etched. The light-shielding layer and the phase-shift layer after etching may have the same or different patterns. If the light-shielding layer and the phase-shift layer after etching have the same pattern, the same patterned photoresist layer is used as a mask during etching. If the light-shielding layer and the phase-shift layer after etching have different patterns, patterned photoresists of different patterns are used as masks during etching.

[0138] In addition, the method for manufacturing the photomask may further include: cleaning the photomask.

[0139] Since the photomask base is formed by adopting the manufacturing method of the photomask base, the cost of manufacturing the photomask base is reduced and the quality of the photomask base is improved.

[0140] The above description is only a description of the preferred embodiments of the present invention and does not limit the scope of the present invention. Any changes and modifications made by ordinary technicians in the field of the present invention based on the above disclosure shall fall within the scope of protection of the claims.

Claims

1. A substrate recycling method for recycling a scrapped photomask, wherein the photomask comprises a substrate and a mask structure formed on the substrate, characterized in that: The substrate recovery method comprises: Providing a plasma etching system; Setting the plasma etching system to a plasma chemical etching mode to remove the mask structure and avoid damaging the substrate surface; The plasma etching system is set to a plasma super polishing mode to polish the surface of the substrate.

2. The substrate recovery method according to claim 1, characterized in that: The plasma etching system comprises: A remote plasma generator is used to emit plasma toward the surface of the photomask.

3. The substrate recovery method according to claim 2, characterized in that: The plasma etching system also includes: an anode, disposed above the photomask; A chuck, used for carrying the photomask; A reaction chamber, wherein the remote plasma generator is disposed outside the reaction chamber and communicated with the reaction chamber, and the anode and the chuck are both disposed in the reaction chamber.

4. The substrate recovery method according to claim 3, characterized in that: The plasma etching system also includes: A direct current power source is connected to the anode and the chuck to generate a direct current bias voltage between the anode and the chuck.

5. The substrate recovery method according to claim 4, characterized in that: The plasma etching system also includes: A coil is arranged outside the reaction chamber, and the coil is used to generate a Magnetic field of the surface.

6. The substrate recovery method according to claim 3, characterized in that: The plasma etching system includes one reaction chamber, and the plasma chemical etching mode and the plasma super polishing mode share the reaction chamber; or, the plasma etching system includes at least two reaction chambers, and the plasma chemical etching mode and the plasma super polishing mode use different reaction chambers.

7. The substrate recovery method according to claim 2, characterized in that: When the plasma etching system is set to the plasma chemical etching mode, the remote plasma generator emits to the surface of the photomask: a highly chemically active plasma generated by ionizing fluorine-containing gas and / or chlorine-containing gas; when the plasma etching system is set to the plasma super polishing mode, the remote plasma generator emits to the surface of the photomask: a chemically inactive plasma generated by ionizing an inert gas.

8. The substrate recovery method according to claim 5, characterized in that: When the plasma etching system is set to the plasma chemical etching mode: the gas pressure in the reaction chamber is 100 Torr~5atm; the DC power supply is in an off state, so that the DC bias is not generated; the temperature of the chuck is 25℃~200℃; no current is connected to the coil, so that the magnetic field is not generated.

9. The substrate recovery method according to claim 5, characterized in that: When the plasma etching system is set to the plasma super polishing mode: the gas pressure in the reaction chamber is <100Torr; the DC power supply is turned on, so that the DC bias voltage generated is 0V~500V; the temperature of the chuck is 25℃~200℃; current is connected to the coil, so that the magnetic field generated is 0T~5T.

10. The substrate recovery method according to claim 1, characterized in that: The front side and / or the back side of the substrate is polished.

11. A method for manufacturing a regenerated photomask substrate, characterized in that: include: Providing a scrapped photomask, the photomask comprising a substrate and a mask structure formed on the substrate; Recycling the substrate of the photomask using the substrate recycling method according to any one of claims 1 to 10 to obtain a regenerated substrate; forming a light shielding layer on the regenerated substrate; A photoresist layer is formed on the light shielding layer.

12. The method for manufacturing a regenerated photomask blank according to claim 11, wherein: Before forming the light shielding layer on the regenerated substrate, the method for manufacturing the regenerated photomask base also includes: A phase shift layer is formed on the regenerated substrate, and the light shielding layer is located on the phase shift layer.

13. The method for manufacturing a regenerated photomask blank according to claim 12, wherein: Before forming the phase shift layer on the regenerated substrate, the method for manufacturing the regenerated photomask base also includes: A spin-on carbon layer is formed on the front side and / or the back side of the regenerated substrate.

14. A method for manufacturing a photomask, characterized in that: include: Forming a photomask blank using the method for manufacturing a regenerated photomask blank according to any one of claims 11 to 13; Patterning the photoresist layer so that the photoresist layer is formed into a patterned photoresist layer; Using the patterned photoresist layer as a mask, etching the light shielding layer to form a patterned light shielding layer on the substrate; The patterned photoresist layer is removed.

15. The method for manufacturing a photomask according to claim 14, wherein: A phase shift layer is formed between the regenerated substrate and the light shielding layer. After etching the light shielding layer using the patterned photoresist layer as a mask, the phase shift layer is also etched.

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