A post-processing method for etching depth

Abstract

The present application relates to the field of etching and discloses a post-processing method for etching depth, comprising obtaining the depth of a groove formed after preliminary etching of a substrate and removal of a mask; determining whether the depth is greater than a target depth; if the depth is greater than the target depth, removing a portion of the substrate from the target surface of the substrate after preliminary etching so that the depth of the groove is equal to the target depth; if the depth is less than the target depth, forming a thin film on the target surface of the substrate other than the groove, the thickness of the thin film being equal to the difference between the depth and the target depth, and the target surface being the surface where the groove is located. When the depth of the etched groove is greater than the target depth, removing a portion of the substrate so that the depth of the groove is equal to the target depth; when the depth of the groove is less than the target depth, forming a thin film on the substrate so that the depth of the groove is equal to the target depth. Therefore, this method can adjust the depth of the groove so that the depth of the groove is equal to the target depth after the etching depth of the groove is too large or too small.

Description

Technical Field

[0001] The present application relates to the field of etching, and in particular to a post-processing method for etching depth. Background Art

[0002] Etching pattern transfer technology is an important micro-nano processing technology. It transfers the pattern of photoresist to the substrate. That is, the photoresist is used as a mask to etch the substrate to form a groove of a certain etching depth on the substrate. Then the photoresist is removed to complete the purpose of pattern transfer.

[0003] The etching accuracy of micro-nanostructures on optical components has a significant impact on their performance, affecting, for example, the diffraction efficiency and fringe contrast of diffractive optical elements. Currently, etch depth is regulated by strictly controlling the etching time based on the etch rate of a substrate material using specific etching parameters (such as gas flow rate, substrate temperature and bias voltage, discharge power, and the density and distribution of the pattern to be etched). However, since the mask on the substrate surface is not removed and it is difficult to accurately calibrate the mask consumption rate, the measurement of etch depth is subject to significant errors. If the etch depth is measured after removing the mask, whether the etch depth is too large or too small, the substrate cannot be directly etched again.

[0004] Therefore, how to solve the above technical problems should be the focus of those skilled in the art. Summary of the Invention

[0005] The purpose of this application is to provide a post-processing method for etching depth to adjust grooves that do not meet the etching depth.

[0006] To solve the above technical problems, the present application provides a post-processing method for etching depth, comprising:

[0007] Obtaining the depth of the groove formed after the substrate is initially etched and the mask is removed;

[0008] determining whether the depth is greater than a target depth;

[0009] If the depth is greater than the target depth, removing a portion of the substrate from the target surface of the substrate after the preliminary etching so that the depth of the groove is equal to the target depth;

[0010] If the depth is less than the target depth, a thin film is produced on the target surface of the substrate except the groove, and the thickness of the thin film is equal to the difference between the depth and the target depth. The target surface is the surface where the groove is located.

[0011] Optionally, removing a portion of the substrate from the target surface of the substrate after the preliminary etching so that the depth of the groove is equal to the target depth includes:

[0012] coating a photoresist on a target surface of the substrate to form a photoresist layer, thereby obtaining a first processed substrate; wherein a difference between a removal rate of the photoresist layer after development and a removal rate of the substrate is no more than 5%;

[0013] determining the thickness of the photoresist layer;

[0014] determining a target removal thickness of the first processed substrate according to the thickness, the depth, and the target depth; wherein the target removal thickness is greater than the thickness;

[0015] etching the first processed substrate from the side where the photoresist layer is located according to the target removal thickness to obtain a new substrate;

[0016] The photoresist in the groove of the new substrate is removed.

[0017] Optionally, determining a target removal thickness of the first processed substrate according to the thickness, the depth, and the target depth includes:

[0018] The target removal thickness is determined according to a first preset formula, where the first preset formula is:

[0019] D1=D0+(H1-H0);

[0020] Wherein, D1 is the target removal thickness, D0 is the thickness of the photoresist layer on the target surface where the groove is located, H1 is the depth of the groove, and H0 is the target depth.

[0021] Optionally, after removing the photoresist in the groove in the new substrate, the method further includes:

[0022] cleaning the new substrate;

[0023] measuring the adjusted depth of the groove on the new substrate;

[0024] Determining whether a difference between the adjusted depth and the depth is less than a preset error;

[0025] If the difference is not less than the preset error, the adjusted depth is set as a new depth, and a step of determining whether the depth is greater than a target depth is performed.

[0026] Optionally, forming a thin film in an area of ​​the target surface of the substrate excluding the groove includes:

[0027] Filling the groove with photoresist to obtain a second processed substrate;

[0028] determining a difference between the depth and the target depth as the thickness of the film;

[0029] Depositing the thin film on the target surface of the substrate after the second treatment; the bonding strength between the thin film and the substrate is greater than the bonding strength between the thin film and the photoresist;

[0030] heating the second processed substrate having the thin film to a temperature greater than a glass transition temperature of the photoresist;

[0031] The photoresist is stripped off, and the thin film combined with the photoresist is removed through the photoresist to obtain a new substrate.

[0032] Optionally, after stripping the photoresist and removing the thin film combined with the photoresist through the photoresist to obtain a new substrate, the method further includes:

[0033] cleaning the new substrate;

[0034] measuring the adjusted depth of the groove on the new substrate;

[0035] Determining whether a difference between the adjusted depth and the depth is less than a preset error;

[0036] If the difference is not less than the preset error, the adjusted depth is set as a new depth, and a step of determining whether the depth is greater than a target depth is performed.

[0037] Optionally, filling the groove with photoresist to obtain the second processed substrate includes:

[0038] coating a positive photoresist on a target surface of the substrate to form a photoresist layer;

[0039] removing the photoresist layer located at the top of the groove;

[0040] The remaining photoresist layer on the substrate is developed to obtain the second processed substrate.

[0041] Optionally, filling the groove with photoresist to obtain the second processed substrate includes:

[0042] coating a positive photoresist on a target surface of the substrate to form a photoresist layer;

[0043] developing the photoresist layer not covering the groove;

[0044] The photoresist layer located on the groove is removed to obtain the second processed substrate.

[0045] Optionally, when the depth of the groove is uneven, the method further comprises:

[0046] determining depth distribution information of the groove according to the depth of the groove;

[0047] determining first removal thickness distribution information of each area of ​​the substrate according to the depth distribution information and target depth distribution uniformity information;

[0048] coating a photoresist on a target surface of the substrate to form a photoresist layer, thereby obtaining a third processed substrate; wherein a difference between a removal rate of the photoresist layer after development and a removal rate of the substrate is no more than 5%;

[0049] Determining thickness distribution information of each area of ​​the photoresist layer;

[0050] determining second removed thickness distribution information of each region of the substrate after the third treatment according to the first removed thickness distribution information of the substrate and the thickness distribution information of the photoresist layer;

[0051] removing each area of ​​the third processed substrate according to the second removal thickness distribution information so as to make the depths of the grooves equal to each other, thereby obtaining a new substrate;

[0052] The photoresist in the groove of the new substrate is removed.

[0053] Optionally, after removing the photoresist in the groove, the method further includes:

[0054] Determining the thickness of the new substrate at the middle position;

[0055] The back side of the new substrate is modified by using ion beam modification technology so that the thickness of each area of ​​the new substrate is equal to the thickness of the middle position; the back side is opposite to the target surface.

[0056] The present application provides a post-processing method for etching depth, comprising: obtaining the depth of a groove formed after a substrate is initially etched and a mask is removed; determining whether the depth is greater than a target depth; if the depth is greater than the target depth, removing a portion of the substrate from a target surface of the substrate after the initial etching so that the depth of the groove is equal to the target depth; if the depth is less than the target depth, forming a thin film on an area of ​​the target surface of the substrate other than the groove, wherein the thickness of the thin film is equal to the difference between the depth and the target depth, and the target surface is the surface where the groove is located.

[0057] It can be seen that in this application, after etching a groove in the substrate and removing the mask, the relationship between the groove depth and the target depth is determined. When the depth of the etched groove is greater than the target depth, part of the substrate is removed from the target surface where the groove is located, that is, the groove depth is shallowed, so that the groove depth is equal to the target depth; when the depth of the groove is less than the target depth, a thin film is formed on the target surface where the groove is located, that is, the groove depth is deepened, so that the groove depth is equal to the target depth. Therefore, the post-processing method of etching depth in this application can adjust the groove depth to make the groove depth equal to the target depth if the groove etching depth is too large or too small. BRIEF DESCRIPTION OF THE DRAWINGS

[0058] In order to more clearly illustrate the embodiments of the present application or the technical solutions of the prior art, the following is a brief introduction to the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0059] Figure 1 The process of a post-processing method for etching depth provided in the embodiment of the present application Figure 1 ;

[0060] Figures 2 to 6 The process flow of a post-processing method for etching depth provided in the embodiment of the present application Figure 1 ;

[0061] Figures 7 to 10 The process flow of a post-processing method for etching depth provided in the embodiment of the present application Figure 2 ;

[0062] Figure 11 The process of a post-processing method for etching depth provided in the embodiment of the present application Figure 2 ;

[0063] Figures 12 to 16 The process flow of a post-processing method for etching depth provided in the embodiment of the present application Figure 3 ;

[0064] Figure 17 This is a schematic diagram of a substrate after etching using a post-processing method for etching depth provided in an embodiment of the present application. DETAILED DESCRIPTION

[0065] In order to enable those skilled in the art to better understand the present application, the present application is further described in detail below in conjunction with the accompanying drawings and specific embodiments. Obviously, the embodiments described are only a part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without making any creative efforts are within the scope of protection of the present application.

[0066] In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention may also be implemented in other ways different from those described herein. Those skilled in the art may make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0067] As mentioned in the background section, current methods for controlling etch depth rely on calibrating the etch rate of a specific etch parameter for a specific substrate material, strictly controlling the etch time. However, because the mask on the substrate surface is not removed and it is difficult to accurately calibrate the mask consumption rate, etch depth measurements are subject to significant errors. If the etch depth is measured after removing the mask, whether the etch depth is too high or too low, the substrate cannot be directly re-etched.

[0068] In view of this, this application provides a post-processing method for etching depth, please refer to Figure 1 , the method may include:

[0069] Step S101: obtaining the depth of the groove formed after the substrate is initially etched and the mask is removed.

[0070] In one embodiment of the present application, before obtaining the depth of the groove formed after the substrate is initially etched and the mask is removed, the following steps may be further included:

[0071] coating a photoresist on the substrate to form a photoresist layer;

[0072] Developing the photoresist layer and etching the substrate to form a groove; wherein the etching method includes but is not limited to any one of RIE etching (reactive ion etching), ICP etching (inductively coupled plasma etching), and chemical wet etching;

[0073] Remove the residual glue that served as the mask, and then clean the substrate.

[0074] It should be noted that the groove depth measurement method is not limited in this embodiment. An appropriate measuring instrument is selected based on the substrate material, the desired etching depth accuracy, and the etching structure. For example, to obtain nanometer-level etching depth on a quartz glass plate, an atomic force microscope or a step profiler is required.

[0075] In this embodiment, the depths of all grooves on the substrate are equal.

[0076] Step S102: determining whether the depth is greater than a target depth.

[0077] The target depth is the required groove depth, which is not limited in this embodiment and depends on the circumstances.

[0078] Step S103: If the depth is greater than the target depth, a portion of the substrate is removed from the target surface of the substrate after the preliminary etching, so that the depth of the groove is equal to the target depth.

[0079] If the groove depth is greater than the target depth, it indicates that the groove has been over-etched and the excess etching depth needs to be removed. In this embodiment, the method for removing the excess etching depth is not limited and can be set by the user.

[0080] As an embodiment, removing a portion of the substrate from the target surface of the substrate after the preliminary etching so that the depth of the groove is equal to the target depth includes:

[0081] Step S1031: coating a photoresist on a target surface of the substrate to form a photoresist layer, thereby obtaining a first processed substrate; the difference between a removal rate of the photoresist layer after development and a removal rate of the substrate is no more than 5%.

[0082] The difference between the removal rate of the photoresist layer after development and the removal rate of the substrate is no more than 5%, that is, the removal rate of the photoresist layer after development is very close to or even equal to the removal rate of the substrate, which facilitates synchronous removal during subsequent etching.

[0083] After the initial etching, the substrate Figure 2 As shown, a groove is etched on one side of the target surface of the substrate 1, and the substrate after the first treatment after coating the photoresist is as follows Figure 3 As shown, the groove is filled with photoresist 2, and has a certain thickness on the surface of the substrate.

[0084] Step S1032: determining the thickness of the photoresist layer.

[0085] The thickness of the photoresist layer determined in this step does not include the thickness of the photoresist in the groove, but only the thickness of the photoresist layer above the groove.

[0086] Step S1033: determining a target removal thickness of the first processed substrate according to the thickness, the depth, and the target depth; the target removal thickness is greater than the thickness.

[0087] As an embodiment, determining a target removal thickness of the first processed substrate according to the thickness, the depth, and the target depth includes:

[0088] The target removal thickness is determined according to a first preset formula, where the first preset formula is:

[0089] D1=D0+(H1-H0); (1)

[0090] Wherein, D1 is the target removal thickness, D0 is the thickness of the photoresist layer on the target surface where the groove is located, H1 is the depth of the groove, and H0 is the target depth.

[0091] Step S1034: etching the first processed substrate from the side where the photoresist layer is located according to the target removal thickness to obtain a new substrate.

[0092] like Figures 4 and 5 As shown, etching is performed from the side where the photoresist layer is located to remove the photoresist and part of the substrate, so that the depth of the remaining groove is equal to the target depth.

[0093] Etching methods include but are not limited to IBE (Ion Beam Etching) or IBF (ion beam figuring).

[0094] Step S1035: removing the photoresist in the groove in the new substrate.

[0095] The photoresist can be cleaned and removed using solvents such as acetone, which is not limited in this embodiment. Figure 6 shown.

[0096] Step S104: If the depth is less than the target depth, a thin film is formed on the target surface of the substrate except the groove, wherein the thickness of the thin film is equal to the difference between the depth and the target depth, and the target surface is the surface where the groove is located.

[0097] When the depth of the groove is less than the target depth, the etching amount is insufficient and the groove depth needs to be deepened. In this embodiment, the method of forming the thin film in the target surface area of ​​the substrate other than the groove is not limited and can be set arbitrarily.

[0098] As an implementation method, forming a thin film in an area of ​​the target surface of the substrate other than the groove includes:

[0099] Step S1041: filling the groove with photoresist to obtain a second processed substrate.

[0100] After the initial etching, the substrate Figure 7 As shown, a groove is etched on one side of the target surface of the substrate 1, and the substrate after the second treatment after coating the photoresist is as follows Figure 8 As shown, only the grooves are filled with photoresist 2 .

[0101] It should be noted that the method for obtaining the second processed substrate is not limited in this embodiment and depends on the circumstances.

[0102] As an implementation method, filling the groove with photoresist to obtain the second processed substrate includes:

[0103] coating a positive photoresist on a target surface of the substrate to form a photoresist layer;

[0104] removing the photoresist layer located at the top of the groove;

[0105] The remaining photoresist layer on the substrate is developed to obtain the second processed substrate.

[0106] In this embodiment, photoresist is coated on the entire target surface of the substrate, and after the residual photoresist on the top of the groove is removed, the substrate surface is developed to leave only the photoresist in the groove.

[0107] As another possible implementation method, filling the groove with photoresist to obtain the second processed substrate includes:

[0108] coating a positive photoresist on a target surface of the substrate to form a photoresist layer;

[0109] developing the photoresist layer not covering the groove;

[0110] The photoresist layer located on the groove is removed to obtain the second processed substrate.

[0111] In this embodiment, photoresist is coated on the entire target surface of the substrate, and then the substrate is developed, and then the photoresist layer in the area above the groove is removed, leaving only the photoresist in the groove. The photoresist layer located above the groove can be removed by IBF.

[0112] Step S1042: determining a difference between the depth and the target depth as the thickness of the film.

[0113] The difference between the depth and the target depth, that is, the smaller value of the groove, is compensated by the film.

[0114] Step S1043: depositing the thin film on the target surface of the second-processed substrate; the bonding strength between the thin film and the substrate is greater than the bonding strength between the thin film and the photoresist.

[0115] like Figure 9 As shown, a thin film 3 is deposited on the front side of the target surface of the substrate after the second treatment.

[0116] The reason the film's bond strength to the substrate must be greater than its bond strength to the photoresist is because the film above the grooves will need to be removed later by removing the photoresist within them, while retaining the film outside the grooves. The greater the difference between the film's bond strength to the substrate and the film's bond strength to the photoresist, the better.

[0117] The thin film deposition process includes but is not limited to any one of thermal evaporation, plasma sputtering, and magnetron sputtering.

[0118] Step S1044: heating the second processed substrate having the thin film, wherein the heating temperature is greater than the glass transition temperature of the photoresist.

[0119] When the heating temperature is greater than the glass transition temperature of the photoresist, the photoresist becomes fluid and the photoresist in the groove collapses and deforms.

[0120] Step S1045: stripping the photoresist, and removing the thin film combined with the photoresist through the photoresist to obtain a new substrate.

[0121] like Figure 10 As shown, by stripping the photoresist, the thin film on the photoresist (that is, the thin film above the groove) can be removed at the same time, leaving the thin film in the area outside the groove.

[0122] The new substrate obtained after etching in the present application can be used as an optical element, for example, a diffractive optical element, a transmissive optical element, a transmissive diffractive optical element, etc.

[0123] In this embodiment, after a groove is etched into the substrate and the mask is removed, the relationship between the groove depth and the target depth is determined. If the etched groove depth exceeds the target depth, a portion of the substrate is removed from the target surface where the groove is located, thereby reducing the groove depth to the target depth. If the groove depth is less than the target depth, a thin film is formed on the target surface where the groove is located, thereby deepening the groove depth to the target depth. Therefore, the etching depth post-processing method in this embodiment can adjust the groove depth to the target depth if the groove depth is too large or too small.

[0124] Based on the above embodiment, in one embodiment of the present application, when the groove depth is greater than the target depth, after removing the photoresist in the groove in the new substrate, the method may further include:

[0125] cleaning the new substrate;

[0126] measuring the adjusted depth of the groove on the new substrate;

[0127] Determining whether a difference between the adjusted depth and the depth is less than a preset error;

[0128] If the difference is not less than the preset error, the adjusted depth is set as a new depth, and a step of determining whether the depth is greater than a target depth is performed.

[0129] It is understandable that when the difference is smaller than the preset error, etching is stopped, and a groove meeting the design requirements is obtained.

[0130] In this embodiment, there is no limitation on the preset error, which can be set by the user.

[0131] After the photoresist is removed, there may be residual photoresist on the new substrate, so the new substrate is cleaned and then the depth of the groove is measured to check whether the adjusted groove depth meets the design requirements. If not, continue to adjust until the groove depth meets the preset error requirements.

[0132] Based on the above embodiment, in one embodiment of the present application, when the groove depth is less than the target depth, the photoresist is stripped, and the thin film combined with the photoresist is removed through the photoresist to obtain a new substrate, and the following steps may be further included:

[0133] cleaning the new substrate;

[0134] measuring the adjusted depth of the groove on the new substrate;

[0135] Determining whether a difference between the adjusted depth and the depth is less than a preset error;

[0136] If the difference is not less than the preset error, the adjusted depth is set as a new depth, and a step of determining whether the depth is greater than a target depth is performed.

[0137] After the photoresist is removed, there may be residual photoresist on the new substrate, so the new substrate is cleaned and then the depth of the groove is measured to check whether the adjusted groove depth meets the design requirements until the groove depth meets the preset error requirements.

[0138] On the basis of any of the above embodiments, in one embodiment of the present application, when the depth of the groove is uneven, the uneven depth of the groove means that the depths of the grooves are not all equal, such as Figure 11 As shown, the post-processing method of etching depth may also include:

[0139] Step S201: Determine the depth distribution information of the groove according to the depth of the groove.

[0140] In one embodiment of the present application, before determining the depth distribution information of the groove according to the depth of the groove, the method may further include:

[0141] coating a photoresist on the substrate to form a photoresist layer;

[0142] developing the photoresist layer and etching the substrate to form a groove;

[0143] Remove the residual glue that served as the mask, and then clean the substrate.

[0144] The depth distribution information refers to the depth of the grooves at various locations on the substrate.

[0145] In actual production, the unevenness of groove etching depth distribution ranges from nanometers to hundreds of nanometers. As the aperture of the optical element increases, the unevenness of etching depth will become more obvious.

[0146] Step S202: determining first removal thickness distribution information of each area of ​​the substrate according to the depth distribution information and target depth distribution uniformity information.

[0147] The first removed thickness distribution information is obtained by subtracting the depth in the depth distribution information from the target depth in the target depth uniform distribution information.

[0148] The first removal thickness distribution information is the thickness of the grooves in each area that needs to be removed. The depths of the grooves in different areas are different, so the thicknesses that need to be removed in different areas are also different.

[0149] Step S203: coating a photoresist on the target surface of the substrate to form a photoresist layer, thereby obtaining a third processed substrate; the difference between the removal rate of the photoresist layer after development and the removal rate of the substrate is no more than 5%.

[0150] The depth of the grooves is not all equal, such as Figure 12 As shown, a groove is etched on one side of the target surface of the substrate 1, the depth of the groove in the middle part is large, and the depth of the groove in the two side areas is small. Figure 13 As shown, the groove is filled with photoresist 2, and has a certain thickness on the surface of the substrate.

[0151] The difference between the removal rate of the photoresist layer after development and the removal rate of the substrate is no more than 5%, that is, the removal rate of the photoresist layer after development is very close to or even equal to the removal rate of the substrate, which facilitates synchronous removal during subsequent etching.

[0152] Step S204: determining thickness distribution information of each region of the photoresist layer.

[0153] The thickness distribution information of the photoresist layer is the thickness of the photoresist layer in different areas on the substrate.

[0154] Step S205 : determining second removed thickness distribution information of each region of the substrate after the third processing according to the first removed thickness distribution information of the substrate and the thickness distribution information of the photoresist layer.

[0155] The second removed thickness distribution information is obtained by adding the thickness in the first removed thickness distribution information and the thickness in the thickness distribution information of the photoresist layer.

[0156] Step S206 : removing each region of the third processed substrate according to the second removal thickness distribution information so as to make the depths of the grooves equal to each other, thereby obtaining a new substrate.

[0157] like Figures 14 and 15 As shown, the third processed substrate is etched, and the etching method can be IBE or IBF, so that the depths of all grooves in the new substrate are equal.

[0158] Step S207: removing the photoresist in the groove in the new substrate.

[0159] like Figure 16 As shown, the photoresist in the groove is completely removed.

[0160] In this embodiment, the grooves with uneven depth distribution on the substrate can be adjusted to grooves with uniform depth distribution, so that the entire etching process has extremely high precision in terms of etching depth.

[0161] Based on the above embodiment, in one embodiment of the present application, after removing the photoresist in the groove, the following steps may be further included:

[0162] Determining the thickness of the new substrate at the middle position;

[0163] The back side of the new substrate is modified by using ion beam modification technology so that the thickness of each area of ​​the new substrate is equal to the thickness of the middle position; the back side is opposite to the target surface.

[0164] The back side of the new substrate is the side without grooves. Figure 16As shown, assuming that the thickness of the middle position is H and the thickness of the two side areas is greater than H, the back surface is trimmed so that the thickness of each area of ​​the new substrate (thickness outside the groove area) is equal, as shown in FIG. Figure 17 shown.

[0165] The thickness of the new substrate outside the groove area affects the phase distribution of the transmitted wavefront. In this embodiment, the thickness of the new substrate outside the groove area is equal, so the phase distribution of the transmitted wavefront is uniform.

[0166] Based on the above embodiment, in one embodiment of the present application, after adjusting the grooves with uneven depth distribution on the substrate to grooves with uniform depth distribution, the following steps may be further included:

[0167] Measuring the adjusted depth of the groove on the new substrate;

[0168] Determining whether the distribution information of the adjusted depth of the grooves on the new substrate meets the preset depth distribution requirements;

[0169] If the preset depth distribution requirement is met, etching is stopped;

[0170] If the preset depth distribution requirement is not met, the adjusted depth of the groove on the new substrate is used as the new depth of the groove, and the step of determining the depth distribution information of the groove according to the depth of the groove is performed.

[0171] The post-processing method of etching depth of the present application also has the following advantages: wide application range, suitable for etching depth control after etching by methods such as chemical wet etching and plasma dry etching. It can achieve nanometer-level precision etching depth control, making up for the shortcomings of etching equipment. It can solve the problem of large errors in the etching depth measured after removing the mask. Based on the existing large-aperture ion beam shaping equipment, this method is suitable for regulating the etching depth and distribution of large-aperture optical elements. The equipment involved in this method is all existing equipment, and there is no need to modify or develop new equipment, and the measurement method is off-line measurement with high measurement accuracy and reliability. It can greatly reduce the scrap rate and improve economic benefits.

[0172] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0173] The above is a detailed introduction to the post-processing method for etching depth provided by the present application. Specific examples are used herein to illustrate the principles and implementation methods of the present application. The description of the above embodiments is only used to help understand the scheme and core ideas of the present application. It should be pointed out that for ordinary technicians in this technical field, without departing from the principles of the present application, several improvements and modifications can be made to the present application, and these improvements and modifications also fall within the scope of protection of the present application.

Claims

1. A post-processing method for etching depth, characterized in that: include: Obtaining the depth of the groove formed after the substrate is initially etched and the mask is removed; determining whether the depth is greater than a target depth; If the depth is greater than the target depth, removing a portion of the substrate from the target surface of the substrate after the preliminary etching so that the depth of the groove is equal to the target depth; If the depth is less than the target depth, a thin film is produced on the target surface of the substrate except the groove, and the thickness of the thin film is equal to the difference between the depth and the target depth. The target surface is the surface where the groove is located.

2. The post-processing method for etching depth according to claim 1, characterized in that: Removing a portion of the substrate from the target surface of the substrate after the preliminary etching so that the depth of the groove is equal to the target depth includes: coating a photoresist on a target surface of the substrate to form a photoresist layer, thereby obtaining a first processed substrate; wherein a difference between a removal rate of the photoresist layer after development and a removal rate of the substrate is no more than 5%; determining the thickness of the photoresist layer; determining a target removal thickness of the first processed substrate according to the thickness, the depth, and the target depth; wherein the target removal thickness is greater than the thickness; etching the first processed substrate from the side where the photoresist layer is located according to the target removal thickness to obtain a new substrate; The photoresist in the groove of the new substrate is removed.

3. The post-processing method for etching depth according to claim 2, wherein: Determining a target removal thickness of the first processed substrate according to the thickness, the depth, and the target depth includes: The target removal thickness is determined according to a first preset formula, where the first preset formula is: D1=D0+(H1-H0); Wherein, D1 is the target removal thickness, D0 is the thickness of the photoresist layer on the target surface where the groove is located, H1 is the depth of the groove, and H0 is the target depth.

4. The post-processing method for etching depth according to claim 2, wherein: After removing the photoresist in the groove of the new substrate, the method further includes: cleaning the new substrate; measuring the adjusted depth of the groove on the new substrate; Determining whether a difference between the adjusted depth and the depth is less than a preset error; If the difference is not less than the preset error, the adjusted depth is set as a new depth, and a step of determining whether the depth is greater than a target depth is performed.

5. The post-processing method for etching depth according to claim 1, wherein: Fabricating a thin film in an area other than the groove on the target surface of the substrate comprises: Filling the groove with photoresist to obtain a second processed substrate; determining a difference between the depth and the target depth as the thickness of the film; Depositing the thin film on the target surface of the substrate after the second treatment; the bonding strength between the thin film and the substrate is greater than the bonding strength between the thin film and the photoresist; heating the second processed substrate having the thin film to a temperature greater than a glass transition temperature of the photoresist; The photoresist is stripped off, and the thin film combined with the photoresist is removed through the photoresist to obtain a new substrate.

6. The post-processing method for etching depth according to claim 5, characterized in that: After stripping the photoresist and removing the thin film combined with the photoresist through the photoresist to obtain a new substrate, the method further includes: cleaning the new substrate; measuring the adjusted depth of the groove on the new substrate; Determining whether a difference between the adjusted depth and the depth is less than a preset error; If the difference is not less than the preset error, the adjusted depth is set as a new depth, and a step of determining whether the depth is greater than a target depth is performed.

7. The post-processing method for etching depth according to claim 5, characterized in that: Filling the groove with photoresist to obtain a second processed substrate comprises: coating a positive photoresist on a target surface of the substrate to form a photoresist layer; removing the photoresist layer located at the top of the groove; The remaining photoresist layer on the substrate is developed to obtain the second processed substrate.

8. The post-processing method for etching depth according to claim 5, characterized in that: Filling the groove with photoresist to obtain a second processed substrate comprises: coating a positive photoresist on a target surface of the substrate to form a photoresist layer; developing the photoresist layer not covering the groove; The photoresist layer located on the groove is removed to obtain the second processed substrate.

9. The post-processing method for etching depth according to any one of claims 1 to 8, characterized in that: When the depth of the groove is uneven, the method further comprises: determining depth distribution information of the groove according to the depth of the groove; determining first removal thickness distribution information of each area of ​​the substrate according to the depth distribution information and target depth distribution uniformity information; coating a photoresist on a target surface of the substrate to form a photoresist layer, thereby obtaining a third processed substrate; wherein a difference between a removal rate of the photoresist layer after development and a removal rate of the substrate is no more than 5%; Determining thickness distribution information of each area of ​​the photoresist layer; determining second removed thickness distribution information of each region of the substrate after the third treatment according to the first removed thickness distribution information of the substrate and the thickness distribution information of the photoresist layer; removing each area of ​​the third processed substrate according to the second removal thickness distribution information so as to make the depths of the grooves equal to each other, thereby obtaining a new substrate; The photoresist in the groove of the new substrate is removed.

10. The post-processing method for etching depth according to claim 9, characterized in that: After removing the photoresist in the groove, the method further includes: Determining the thickness of the new substrate at the middle position; The back side of the new substrate is modified by using ion beam modification technology so that the thickness of each area of ​​the new substrate is equal to the thickness of the middle position; the back side is opposite to the target surface.

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