Acid bath wet etching method

Abstract

The present invention provides an acid tank wet etching method, comprising a relationship curve establishing step, an etching rate budgeting step, a first judging step, a second judging step, and a third judging step, wherein, for different types of products, a relationship curve of respective corresponding etching rates varying with the amount of goods being run is established, before running goods, for multiple groups of products to be run online, according to the type and amount of each group of products to be run, based on the corresponding relationship curve and the current acid tank silicon oxide etching rate, the etching rate corresponding to each group of products to be run after running goods is budgeted, and then, according to the range of the current acid tank silicon oxide etching rate, one group of products to be run online is selected to run goods or perform a small acid change, and finally the acid tank etching rate is stabilized near the target etching rate. In the present invention, even if different types of products run goods through the acid tank, the acid tank etching rate can still remain stable, the stability of the production process can be improved, and the product quality can be guaranteed.

Description

Technical Field

[0001] The invention belongs to the technical field of semiconductors and relates to an acid tank type wet etching method. Background Art

[0002] During chip production, the pad silicon nitride removal (PAD SIN RM) process involves a tank wet etcher, using a phosphoric acid bath to remove the silicon nitride. During this process, silicic acid is generated in the bath. To ensure clean removal, a certain amount of overetching occurs during this process, which involves partially etching away the pad silicon oxide layer beneath the silicon nitride film. However, due to the wide variety of chip product types, the amount of overetch (OE) varies between products, causing instability in the silicon oxide etch rate (H3PO4_OX_ER) in the phosphate bath, which in turn causes fluctuations in the inline thickness (THK) of the pad oxide layer after etching the silicon nitride film.

[0003] Currently, the phosphate baths of tank-type wet etching tools are equipped with a small acid change feature. This feature adjusts the silicic acid concentration in the bath when the cumulative value (number of wafers multiplied by process time) reaches a certain value. This solution can control the H3PO4_OX_ER to a certain extent, but if the ratio of products with different overetch amounts is unbalanced, the etch rate can still be too high or too low, ultimately causing inline chart instability, thus affecting production process stability and product quality.

[0004] Therefore, how to improve the etching rate stability of acid tank wet etching to ensure product quality has become an important technical problem that needs to be solved urgently by those skilled in the art.

[0005] It should be noted that the above introduction to the technical background is merely intended to provide a clear and complete description of the technical solutions of this application and facilitate understanding by those skilled in the art. Simply because these solutions are described in the background technology section of this application, it should not be assumed that the above technical solutions are well known to those skilled in the art. Summary of the Invention

[0006] In view of the above-mentioned shortcomings of the prior art, the object of the present invention is to provide an acid tank wet etching method to solve the problem in the prior art that the unstable acid tank etching rate affects the stability of the production process and product quality.

[0007] To achieve the above-mentioned and other related purposes, the present invention provides an acid tank wet etching method, comprising the following steps:

[0008] Relationship curve establishment steps: For different types of products, establish the corresponding relationship curve between the acid tank silicon oxide etching rate and the sales volume;

[0009] Etching rate estimation step: obtaining the current acid bath silicon oxide etching rate ER, and for multiple groups of products to be shipped online, according to the type and shipment volume of each group of products to be shipped, based on the corresponding relationship curve and the current acid bath silicon oxide etching rate ER, estimating the corresponding acid bath silicon oxide etching rate a for each group of products to be shipped after shipping;

[0010] The first judgment step: determine whether ER satisfies M<ER<N. If so, randomly select a group of products from all the products to be shipped online for shipping. If not, proceed to the second judgment step, where M is a first preset value less than the target etching rate T, and N is a second preset value greater than the target etching rate T.

[0011] The second judgment step: determine whether ER satisfies S<ER≤M. If so, prioritize selecting a group of products with a>S and the smallest absolute value of |aT| from all online products to be shipped for shipping. If none of the online products to be shipped meet a>S, select a group of products with a≤S and the smallest absolute value of |aT| for shipping. If not, proceed to the third judgment step, where S is a third preset value less than M.

[0012] The third judgment step: determine whether ER satisfies ER≥N. If so, select a group of products with the smallest absolute value of |aT| from all the products to be run online for running. If not, perform a small acid change.

[0013] Optionally, the acid tank includes a phosphoric acid tank, and the target etching film layer of the product includes a silicon nitride film, and the silicon nitride film covers the silicon oxide film.

[0014] Optionally, the relationship curve is a linear relationship curve with a negative slope.

[0015] Optionally, different types of products have their own corresponding process menus, and the process menus include thickness data of the target etched film layer.

[0016] Optionally, the relationship curve establishing step includes:

[0017] Select a process menu from multiple process menus, and measure the acid tank silicon oxide etching rate after completing different run volumes for the selected process menu to obtain multiple data points;

[0018] Based on the fitting of multiple data points, the benchmark relationship curve formula Y=-AX+B is obtained, where X is the run-out amount, Y is the acid tank silicon oxide etching rate after the run-out is completed, -A is the slope, and B is the acid tank silicon oxide etching rate when the run-out amount is 0;

[0019] Based on the benchmark relationship curve formula, the relationship curve formulas of the acid tank silicon oxide etching rate corresponding to other process menus as the running volume changes are derived.

[0020] Optionally, the relationship curve formula of the etching rate corresponding to each of the other process menus derived according to the benchmark relationship curve formula changes with the running volume is Y = -(Ae / d)X+B, where d is the thickness of the target etching film layer in the selected process menu, and e is the thickness of the target etching film layer in the process menu from which the relationship curve is derived.

[0021] Optionally, in the etching rate estimation step, the corresponding acid bath silicon oxide etching rate of each group of products to be shipped is estimated based on the corresponding relationship curve and the current acid bath silicon oxide etching rate ER. The formula used is a i =-A i Q i +ER, where, a i is the acid bath silicon oxide etching rate corresponding to a group of products to be sold after the products are sold, -A i is the slope of the relationship curve corresponding to the group of products to be shipped, Q i The calculated delivery volume of a group of products to be shipped.

[0022] Optionally, in the etching rate estimation step, a method of obtaining the current acid bath silicon oxide etching rate ER includes actual measurement or calculation.

[0023] Optionally, after the small acid change, the silicon oxide etching rate of the acid tank returns to the range of M to N.

[0024] Optionally, after selecting a group of products from all products to be shipped online for shipping or performing a small acid change, the process returns to the etching rate budgeting step.

[0025] As described above, the acid tank wet etching method of the present invention includes a relationship curve establishment step, an etching rate budget step, a first judgment step, a second judgment step and a third judgment step, wherein, for different types of products, a relationship curve of the etching rate corresponding to each other is established as the amount of goods to be run. Before running goods, for multiple groups of products to be run online, according to the type and amount of goods to be run in each group, based on the corresponding relationship curve and the current acid tank silicon oxide etching rate, the etching rate corresponding to each group of products to be run after running goods is budgeted. Afterwards, after the previous group of products has completed running goods, according to the range of the current acid tank silicon oxide etching rate, a group of products to be run in multiple groups of products to be run is selected online to run goods or to perform a small acid change, so that the acid tank etching rate is finally stabilized near the target etching rate. In the acid tank wet etching method of the present invention, even if different types of products run goods over the acid tank, the acid tank silicon oxide etching rate can still remain stable. This balanced etching rate can improve the stability of the production process, ensure product quality, and avoid affecting product performance due to the fluctuation of the acid tank silicon oxide etching rate. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 The graph shows the relationship between silicate concentration and phosphate bath silicon oxide etching rate, which is obtained by fitting the measured silicate concentration and the corresponding acid bath silicon oxide etching rate data.

[0027] Figure 2 The graph shows the relationship between the silicon oxide etching rate in the phosphate bath and the run volume corresponding to a selected process menu.

[0028] Figure 3 Shown is a curve showing the relationship between the silicon oxide etch rate in the phosphate bath and the run rate, which is derived for one of the other process menus.

[0029] Figure 4 A logic control diagram for controlling the stability of silicon oxide etching rate in a phosphoric acid bath in one embodiment is shown. DETAILED DESCRIPTION

[0030] The following describes the embodiments of the present invention through specific examples. Those skilled in the art will readily understand the other advantages and benefits of the present invention from the disclosure herein. The present invention may also be implemented or applied through various other specific embodiments, and the details in this specification may be modified or altered based on different perspectives and applications without departing from the spirit of the present invention.

[0031] It should be emphasized that the term "include / comprising" when used herein refers to the presence of features, integers, steps or components, but does not exclude the presence or addition of one or more other features, integers, steps or components.

[0032] Features described and / or illustrated with respect to one embodiment may be used in the same or similar manner in one or more other embodiments, combined with features in other embodiments, or substituted for features in other embodiments.

[0033] For example, when describing the embodiments of the present invention, schematic diagrams illustrating device structures may be partially enlarged for ease of explanation. These schematic diagrams are merely illustrative and should not limit the scope of the present invention. Furthermore, in actual production, three-dimensional dimensions, including length, width, and depth, should be included.

[0034] For convenience, spatially relative terms such as "under," "below," "below," "below," "above," and "on" may be used herein to describe the relationship of one element or feature to other elements or features shown in the drawings. It will be understood that these spatially relative terms are intended to encompass orientations of the device in use or operation in addition to the orientation depicted in the drawings. Additionally, when a layer is referred to as being "between" two layers, it can be the only layer between the two layers, or one or more intervening layers may also be present.

[0035] In the context of the present application, a structure described as a first feature being "above" a second feature may include embodiments where the first and second features are in direct contact, and may also include embodiments where additional features are formed between the first and second features, such that the first and second features may not be in direct contact.

[0036] It should be noted that the illustrations provided in this embodiment are only used to schematically illustrate the basic concept of the present invention. Therefore, the illustrations only show components related to the present invention and are not drawn according to the number, shape and size of components in actual implementation. In actual implementation, the type, quantity and proportion of each component can be changed at will, and the component layout type may also be more complicated.

[0037] The present invention provides an acid tank wet etching method, comprising the following steps:

[0038] Relationship curve establishment steps: For different types of products, establish the corresponding relationship curve between the acid tank silicon oxide etching rate and the sales volume;

[0039] Etching rate estimation step: obtaining the current acid bath silicon oxide etching rate ER, and for multiple groups of products to be shipped online, according to the type and shipment volume of each group of products to be shipped, based on the corresponding relationship curve and the current acid bath silicon oxide etching rate ER, estimating the corresponding acid bath silicon oxide etching rate a for each group of products to be shipped after shipping;

[0040] The first judgment step: determine whether ER satisfies M<ER<N. If so, randomly select a group of products from all the products to be shipped online for shipping. If not, proceed to the second judgment step, where M is a first preset value less than the target etching rate T, and N is a second preset value greater than the target etching rate T.

[0041] The second judgment step: determine whether ER satisfies S<ER≤M. If so, prioritize selecting a group of products with a>S and the smallest absolute value of |aT| from all online products to be shipped for shipping. If none of the online products to be shipped meet a>S, select a group of products with a≤S and the smallest absolute value of |aT| for shipping. If not, proceed to the third judgment step, where S is a third preset value less than M.

[0042] The third judgment step: determine whether ER satisfies ER≥N. If so, select a group of products with the smallest absolute value of |aT| from all the products to be run online for running. If not, perform a small acid change.

[0043] Specifically, the present invention establishes a relationship curve between the acid tank etching rate and the run-off volume of different product types (corresponding to different process menus) through actual measurement and calculation methods. Before running the product, the acid tank silicon oxide etching rate of all product groups to be run on the line can be estimated based on the corresponding relationship curve. Then, based on the current range of the acid tank silicon oxide etching rate, the product is selected online, and finally the etching rate is stabilized near the target value.

[0044] As an example, the acid tank can be a phosphoric acid tank or other applicable acid tank. When the acid tank is a phosphoric acid tank, the target etching film layer of the product includes a silicon nitride film, and the silicon nitride film is covered on the silicon oxide film. The silicon nitride film is a dielectric layer film widely used in CMOS processes and can be obtained by chemical vapor deposition or atomic layer deposition. The main application is as a hard mask for etching, or as a stop layer for chemical mechanical polishing (CMP) and dry etching. When removing the silicon nitride film, the etching selectivity of the adjacent film layer is mainly considered. For example, in some embodiments, the product also includes a silicon oxide film, and the silicon nitride film is covered on the surface of the silicon oxide film. When removing the silicon nitride film, it is necessary to ensure that the online thickness of the silicon oxide film thereunder is stable.

[0045] Specifically, when using a phosphoric acid tank to remove silicon nitride, the main components of the reaction are silicon nitride and water, and phosphoric acid only acts as a catalyst in this reaction. The reaction formula is as follows:

[0046]

[0047] Among them, H2SiO3 is silica generated by the reaction of silicon nitride and water, which is dissolved in the phosphoric acid solution.

[0048] Specifically, the present invention uses a control wafer to measure the silicon oxide etching rate in a phosphoric acid tank. Specifically, a control wafer with a silicon oxide layer of a certain thickness on its surface is placed in the phosphoric acid tank. After etching for a certain period of time (for example, 1 minute), the control wafer is taken out and the thickness of the remaining silicon oxide layer is measured. The silicon oxide etching rate in the phosphoric acid tank can be calculated based on the thickness change of the silicon oxide layer and the etching time.

[0049] As an example, see Figure 1 , which shows the relationship curve y=ax+b between silica concentration and etching rate obtained by fitting the measured silica concentration and the corresponding phosphoric acid bath silicon oxide etching rate data. Among them, the horizontal axis is silica concentration, the vertical axis is the silicon oxide etching rate of the phosphoric acid bath, a is the silica concentration correction coefficient, and b is the silicon oxide etching rate correction coefficient. It can be seen that the silica concentration and the silicon oxide etching rate are linearly related. The principle is that for the same process menu (recipe), the more the run-out volume, the more silicon nitride film is etched away in the phosphoric acid bath, and the more silica is generated, which increases the silica concentration in the phosphoric acid solution and reduces the silicon oxide etching rate.

[0050] Specifically, it can be inferred from the above analysis that when running the same product, the silicon oxide etching rate of the acid tank is also linearly related to the running volume.

[0051] As an example, in the relationship curve establishment step of the present invention, for different types of products, the relationship curves of the acid tank silicon oxide etching rate corresponding to the change in the sales volume are linear relationship curves with a negative slope.

[0052] As an example, different types of products have their own corresponding process menus, and the process menus include thickness data of a target etching film layer. Different types of products have different thicknesses of the target etching film layer.

[0053] As an example, the relationship curve establishing step includes:

[0054] (1) selecting a process menu from multiple process menus, and measuring the acid tank silicon oxide etching rate after completing different running volumes for the selected process menu to obtain multiple data points;

[0055] (2) Based on the fitting of multiple data points, a benchmark relationship curve formula Y=-AX+B is obtained, where X is the run-out amount, Y is the acid tank silicon oxide etching rate after the run-out is completed, -A is the slope, and B is the acid tank silicon oxide etching rate when the run-out amount is 0;

[0056] (3) Based on the benchmark relationship curve formula, the relationship curve formulas of the acid tank silicon oxide etching rate corresponding to other process menus and the change in the running volume are derived.

[0057] As an example, in the above step (1), the product corresponding to the selected process menu can be a product with a relatively large sales volume, so as to be more in line with the actual production situation.

[0058] As an example, in the above step (1), when testing different run-off amounts, the acid tank used is the original acid tank that has not been run-off before. For example, for the phosphoric acid tank, the phosphoric acid solution therein is used for the first time and has not been run-off. The etching solution does not contain silicic acid generated by run-off, thereby eliminating interference factors. In addition, since the silicon oxide etching rate of the original acid tank is relatively high, for example, When conducting tests with different run volumes, experimental wafers can be used.

[0059] As an example, see Figure 2 , which shows the relationship curve between the silicon oxide etching rate in the phosphate bath and the running volume corresponding to a selected process menu. It can be seen that the silicon oxide etching rate in the phosphate bath is linearly negatively correlated with the running volume, and the etching rate decreases with the increase of the running volume.

[0060] As an example, the relationship curve formula of the etching rate corresponding to each of the other process menus derived according to the benchmark relationship curve formula changes with the running volume is Y = -(Ae / d)X+B, where d is the thickness of the target etching film layer in the selected process menu, and e is the thickness of the target etching film layer in the process menu from which the relationship curve is derived.

[0061] As an example, see Figure 3 , which shows the relationship between the acid bath silicon oxide etching rate and the running volume derived from one of the other process menus. The e value corresponding to the process menu is greater than the d value, so Ae / d>A, that is, the slope is larger. It can also be seen from the figure that relative to Figure 2 , Figure 3 The relationship curve is steeper.

[0062] Specifically, among all the obtained relationship curves, the larger the slope, the thicker the film layer to be etched. Under the same running volume conditions, more material is etched away, and the acid tank etching rate decreases faster. The smaller the slope, the smaller the thickness of the film layer to be etched. Under the same running volume conditions, less material is etched away, and the acid tank etching rate decreases slower. Therefore, the change in the acid tank silicon oxide etching rate of all product groups to be run online after running can be estimated based on the relationship curves of different process menus, and combined with the current acid tank silicon oxide etching rate, the corresponding acid tank silicon oxide etching rate a of each group of products to be run after running can be estimated.

[0063] As an example, in the etching rate estimation step, based on the corresponding relationship curve and the current acid tank silicon oxide etching rate ER, the corresponding acid tank silicon oxide etching rate of each group of products to be shipped is estimated as follows: i =-A i Q i +ER, where, a i is the acid bath silicon oxide etching rate corresponding to a group of products to be sold after the products are sold, -A i is the slope of the relationship curve corresponding to the group of products to be shipped, Q i The calculated delivery volume of a group of products to be shipped. Usually, the delivery volume is the number of wafers in a group of products to be shipped.

[0064] As an example, in the etching rate estimation step, the current acid bath silicon oxide etching rate ER is obtained by actual measurement or calculation.

[0065] As an example, if the acid tank is used for the first time or for the first time after a small acid change, the current acid tank silicon oxide etching rate ER is obtained by actual measurement. If the acid tank has run through the previous batch of goods, the current acid tank silicon oxide etching rate ER is calculated based on the relationship curve between the acid tank silicon oxide etching rate before the previous batch of goods and the corresponding previous batch of goods.

[0066] As an example, after performing the small acid change, the silicon oxide etching rate of the acid tank returns to the range of M to N.

[0067] As an example, after selecting a group of products from all the products to be shipped online or after a small acid change, return to the etching rate budget step to perform a new round of judgment and product selection, so that the acid tank etching rate is always stable near the target etching rate.

[0068] As an example, see Figure 4 , which shows a logic control diagram for controlling the stability of silicon oxide etching rate in a phosphate bath in one embodiment, including:

[0069] (1) Establish the relationship curve between the silicon oxide etching rate in the phosphate bath and the volume of goods sold for different types of products;

[0070] (2) Obtain the current silicon oxide etching rate in the phosphate bath and record it as ER. Before the next batch of products are run, estimate the silicon oxide etching rate in the phosphate bath after each batch of products to be run on the production line. The estimated result is recorded as a.

[0071] (3) Set the target etching rate T to When 2.4<ER<2.6, that is, when the etching rate is close to the target etching rate, goods can be randomly selected from the line, that is, random scheduling;

[0072] (4) When 2.2<ER≤2.4, that is, the etching rate is less than the target etching rate and deviates greatly, but does not meet the acid replacement standard, the product group with a>2.2 and the smallest absolute value of |a-2.5| is preferentially selected for running. When all products to be run online do not meet a>2.2, the product group with a≤2.2 and the smallest absolute value of |a-2.5| is selected for running;

[0073] (5) When ER ≥ 2.6, that is, the etching rate is greater than the target etching rate and deviates significantly, the product group with the smallest absolute value of |a-2.5| is prioritized for shipping;

[0074] (6) When ER≤2.2, that is, when the etching rate is too low, a small acid change will be performed. After each small acid change, the silicate concentration in the phosphoric acid tank will decrease and the ER will increase by about 0.3.

[0075] It should be noted that the above specific numerical values ​​are only examples, and in actual implementation, appropriate range endpoint values ​​can be set according to specific process requirements.

[0076] In the above method, for a selected process menu, according to the silicon oxide etching rate actually measured in the phosphoric acid tank under different running volume conditions, a benchmark relationship curve of the running volume and the silicon oxide etching rate in the phosphoric acid tank is established, and according to the benchmark relationship curve formula, the relationship curve formula of the acid tank silicon oxide etching rate corresponding to each of the other process menus changes with the running volume, so that the etching rate of the corresponding product type under different running volumes can be estimated. Before running, according to the current acid tank silicon oxide etching rate and the preset selection conditions, the product group that meets the selection conditions is selected from the products with the estimated etching rate for discharge, and finally the etching rate balance is achieved. In other words, by the above method, the stability of the silicon oxide etching rate of the phosphoric acid tank can be controlled, even if different types of products pass through the H3PO4 tank, the acid tank silicon oxide etching rate can still remain stable, and then the stability of the online product can be controlled, and finally the chip performance will not be affected by the fluctuation of the acid tank silicon oxide etching rate.

[0077] In summary, the acid tank wet etching method of the present invention includes a relationship curve establishment step, an etching rate budget step, a first judging step, a second judging step and a third judging step, wherein, for different types of products, a relationship curve of the etching rate corresponding to each other is established as the amount of goods to be run. Before running goods, for multiple groups of products to be run online, according to the type and amount of goods to be run in each group of products to be run, based on the corresponding relationship curve and the current acid tank silicon oxide etching rate, the etching rate corresponding to each group of products to be run after running goods is budgeted. Afterwards, after the previous group of products has completed running goods, according to the range in which the current acid tank silicon oxide etching rate is located, a group of products to be run in multiple groups of products to be run is selected online to run goods or to perform a small acid change, so that the acid tank etching rate is finally stabilized near the target etching rate. In the acid tank wet etching method of the present invention, even if different types of products run goods over the acid tank, the acid tank etching rate can still remain stable. This balanced etching rate can improve the stability of the production process, ensure product quality, and avoid affecting product performance due to the fluctuation of the acid tank silicon oxide etching rate. Therefore, the present invention effectively overcomes various shortcomings of the prior art and has high industrial utilization value.

[0078] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the present invention. Anyone skilled in the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by one of ordinary skill in the art without departing from the spirit and technical principles disclosed herein are intended to be covered by the claims of the present invention.

Claims

1. An acid tank wet etching method, characterized in that: The following steps are involved: Relationship curve establishment steps: For different types of products, establish the corresponding relationship curve between the acid tank silicon oxide etching rate and the sales volume; Etching rate estimation step: obtaining the current acid bath silicon oxide etching rate ER, and for multiple groups of products to be shipped online, according to the type and shipment volume of each group of products to be shipped, based on the corresponding relationship curve and the current acid bath silicon oxide etching rate ER, estimating the corresponding acid bath silicon oxide etching rate a for each group of products to be shipped after shipping; The first judgment step: determine whether ER satisfies M<ER<N. If so, randomly select a group of products from all the products to be shipped online for shipping. If not, proceed to the second judgment step, where M is a first preset value less than the target etching rate T, and N is a second preset value greater than the target etching rate T. The second judgment step: determine whether ER satisfies S<ER≤M. If so, prioritize selecting a group of products with a>S and the smallest absolute value of |aT| from all online products to be shipped for shipping. If none of the online products to be shipped meet a>S, select a group of products with a≤S and the smallest absolute value of |aT| for shipping. If not, proceed to the third judgment step, where S is a third preset value less than M. The third judgment step: determine whether ER satisfies ER≥N. If so, select a group of products with the smallest absolute value of |aT| from all the products to be run online for running. If not, perform a small acid change.

2. The acid bath wet etching method according to claim 1, wherein: The acid tank includes a phosphoric acid tank, and the target etching film layer of the product includes a silicon nitride film, and the silicon nitride film covers the silicon oxide film.

3. The acid tank wet etching method according to claim 1, wherein: The relationship curve is a linear relationship curve and has a negative slope.

4. The acid tank wet etching method according to claim 1, wherein: Different types of products have their own corresponding process menus, and the process menus include thickness data of target etched film layers.

5. The acid tank wet etching method according to claim 4, wherein: The relationship curve establishing step includes: Select a process menu from multiple process menus, and measure the acid tank silicon oxide etching rate after completing different run volumes for the selected process menu to obtain multiple data points; Based on the fitting of multiple data points, the benchmark relationship curve formula Y=-AX+B is obtained, where X is the run-out amount, Y is the acid tank silicon oxide etching rate after the run-out is completed, -A is the slope, and B is the acid tank silicon oxide etching rate when the run-out amount is 0; Based on the benchmark relationship curve formula, the relationship curve formulas of the acid tank silicon oxide etching rate corresponding to other process menus as the running volume changes are derived.

6. The acid tank wet etching method according to claim 5, wherein: The relationship curve formula of the etching rate corresponding to each of the other process menus derived according to the benchmark relationship curve formula changes with the running volume is Y=-(Ae / d)X+B, where d is the thickness of the target etching film layer in the selected process menu, and e is the thickness of the target etching film layer in the process menu from which the relationship curve is derived.

7. The acid tank wet etching method according to claim 6, wherein: In the etching rate estimation step, based on the corresponding relationship curve and the current acid tank silicon oxide etching rate ER, the corresponding acid tank silicon oxide etching rate of each group of products to be shipped is estimated. The formula used is a i =-A i Q i +ER, where, a i is the calculated acid bath silicon oxide etching rate for a group of products to be sold after the products are sold, -A i is the slope of the relationship curve corresponding to the group of products to be shipped, Q i The calculated delivery volume of a group of products to be shipped.

8. The acid tank wet etching method according to claim 1, wherein: In the etching rate estimation step, the current acid bath silicon oxide etching rate ER is obtained by actual measurement or calculation.

9. The acid tank wet etching method according to claim 1, wherein: After the small acid change, the silicon oxide etching rate of the acid tank returns to the range of M to N.

10. The acid tank wet etching method according to claim 1, wherein: After selecting a group of products from all products to be shipped online for shipping or performing a small acid change, the process returns to the etching rate budgeting step.

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