Acid tank type wet etching method

Abstract

The invention provides an acid tank type wet etching method, which comprises a relation curve establishment step, an etching rate budgeting step, a first judgment step, a second judgment step and a third judgment step, and is characterized in that for different types of products, relation curves of corresponding etching rates along with the change of the running amount are established, and before the running amount, the corresponding etching rates are calculated; for multiple groups of to-be-run products on the line, according to the type and run quantity of each group of to-be-run products, the corresponding etching rate of each group of to-be-run products after run is calculated based on the corresponding relation curve and the current acid tank silicon oxide etching rate, and then the etching rate of each group of to-be-run products after run is calculated according to the range of the current acid tank silicon oxide etching rate. And selecting one group of products to be transferred on the line for transferring or small acid exchange, and finally enabling the etching rate of the acid tank to be stabilized near the target etching rate. According to the method, even if different types of products run out of the acid tank, the etching rate of the acid tank can still be kept stable, the stability of the production process can be improved, and the product quality is 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] In the chip production process, the pad silicon nitride removal (PAD SIN RM) process will go through a tank wet etching machine, that is, using a phosphoric acid bath to remove silicon nitride. During this process, silicic acid will be generated in the phosphoric acid bath. When using a phosphoric acid bath to remove silicon nitride, in order to ensure clean removal, a certain amount of over-etching will be performed, that is, the pad silicon oxide layer under the silicon nitride film will be partially etched away. However, due to the large number of chip product types, the amount of over-etching (OE) between different products is different, causing the instability of the silicon oxide etching rate (H3PO4_OX_ER) in the phosphoric acid bath, which in turn causes the online thickness (Inline THK) of the pad oxide layer after the silicon nitride film is etched to fluctuate.

[0003] At present, the phosphoric acid tank of the tank-type wet etching machine is equipped with a small acid change, that is, when the number of wafers × process time accumulates to a certain value, a small acid change is performed to adjust the concentration of silicate in the phosphoric acid tank. This solution can control H3PO4_OX_ER to a certain extent, but when the product ratio of different over-etching amounts is unbalanced, it will still cause the etching rate to be too high or too low, and ultimately cause the inline chart to be unstable, thereby affecting the stability of the production process 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 only for the convenience of providing a clear and complete description of the technical solutions of the present application and for the convenience of understanding by those skilled in the art. It cannot be considered that the above technical solutions are well known to those skilled in the art simply because they are described in the background technology section of the present application. 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 stability of the production process and the product quality are affected due to the unstable acid tank etching rate.

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

[0008] Steps for establishing the relationship curve: for different types of products, establish the relationship curve between the acid tank silicon oxide etching rate and the running 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 shipping 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 of each group of products to be shipped after shipping;

[0010] The first judgment step: judging whether ER satisfies M<ER<N. If so, a group of products to be shipped online is randomly selected for shipping. If not, the second judgment step is performed, wherein 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: judge whether ER satisfies S<ER≤M. If so, a group of products with a>S and the smallest absolute value of |aT| are selected from all the online products to be sold. When all the online products to be sold do not satisfy a>S, a group of products with a≤S and the smallest absolute value of |aT| are selected for selling. If not, the third judgment step is performed, wherein 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 and the slope is a negative number.

[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 different running 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 amount, Y is the acid tank silicon oxide etching rate after the run is completed, -A is the slope, and B is the acid tank silicon oxide etching rate when the run 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 and the change in running volume are derived.

[0020] Optionally, the relationship curve formula of the etching rate corresponding to other process menus derived from the benchmark relationship curve formula changes with the running volume is Y=-(Ae / d)X+B, wherein 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, based on the corresponding relationship curve and the current acid bath silicon oxide etching rate ER, the corresponding acid bath silicon oxide etching rate of each group of products to be shipped is estimated to be 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 being sold, -A i is the slope of the relationship curve corresponding to the group of products to be shipped, Q i The calculated sales volume of a group of products to be shipped.

[0022] Optionally, in the etching rate budgeting step, the current acid bath silicon oxide etching rate ER is obtained by actual measurement or calculation.

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

[0024] Optionally, after a group of products are selected from all products to be shipped online for shipping or after a small acid change, the etching rate budgeting step is returned to.

[0025] As described above, the acid tank wet etching method of the present invention includes a relationship curve establishment step, an etching rate budgeting 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 with the change of the running quantity, before running, for multiple groups of products to be run online, according to the type and running quantity 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 is budgeted, and then after the previous group of products completes running, according to the range of the current acid tank silicon oxide etching rate, a group of products to be run online is selected from multiple groups of products to be run to run or to change the acid, and finally the acid tank etching rate is stabilized near the target etching rate. In the acid tank wet etching method of the present invention, even if different types of products run over the acid tank, the acid tank silicon oxide etching rate can still remain stable, and 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 running 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 running volume 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, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention.

[0031] It should be emphasized that the term “include / comprises” 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 in detail, for the sake of convenience, the schematic diagrams showing the device structure will not be partially enlarged according to the general scale, and the schematic diagrams are only examples, which should not limit the scope of protection of the present invention. In addition, in actual production, the three-dimensional dimensions of length, width and depth should be included.

[0034] For ease of description, spatially relative terms such as "under", "below", "below", "below", "above", "on", etc. may be used herein to describe the relationship of one element or feature shown in the drawings to other elements or features. It will be understood that these spatially relative terms are intended to encompass other orientations of the device in use or operation in addition to the orientation depicted in the drawings. In addition, 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 in which a first feature is described as being "above" a second feature may include embodiments in which the first and second features are in direct contact, and may also include embodiments in which 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 illustrate the basic concept of the present invention in a schematic manner, and therefore the illustrations only show components related to the present invention rather than being drawn according to the number, shape and size of components in actual implementation. In actual implementation, the type, quantity and proportion of each component may be changed arbitrarily, and the component layout may also be more complicated.

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

[0038] Steps for establishing the relationship curve: for different types of products, establish the relationship curve between the acid tank silicon oxide etching rate and the running 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 shipping 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 of each group of products to be shipped after shipping;

[0040] The first judgment step: judging whether ER satisfies M<ER<N. If so, a group of products to be shipped online is randomly selected for shipping. If not, the second judgment step is performed, wherein 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: judge whether ER satisfies S<ER≤M. If so, a group of products with a>S and the smallest absolute value of |aT| are selected from all the online products to be sold. When all the online products to be sold do not satisfy a>S, a group of products with a≤S and the smallest absolute value of |aT| are selected for selling. If not, the third judgment step is performed, wherein 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 after running the product can be estimated according to the corresponding relationship curve, and then the product is selected online according to the current range of the acid tank silicon oxide etching rate, so that the etching rate is finally stabilized near the target value.

[0044] As an example, the acid tank can be a phosphoric acid tank or other applicable acid tanks. 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, wherein the silicon nitride film is a dielectric layer film widely used in CMOS technology, which 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 covers 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 a phosphoric acid tank is used to remove silicon nitride, the main components of the reaction are silicon nitride and water, and phosphoric acid only serves 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 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 the 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 by the thickness change of the silicon oxide layer and the etching time.

[0049] As an example, see Figure 1 , showing the relationship curve y=ax+b between silica concentration and etching rate obtained by fitting the measured silica concentration and the corresponding phosphate bath silicon oxide etching rate data, wherein the horizontal axis is the silica concentration, the vertical axis is the silicon oxide etching rate in the phosphate 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 recipe, the more the running volume is, the more silicon nitride film is etched away in the phosphate 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 establishing 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 running volume are established as linear relationship curves, and the slope is negative.

[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, wherein X is the run amount, Y is the acid tank silicon oxide etching rate after the run is completed, -A is the slope, and B is the acid tank silicon oxide etching rate when the run 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 running volume are derived.

[0057] As an example, in the above step (1), the product corresponding to the selected process menu may 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 amounts of leaching, the acid tank used is an original acid tank that has not been leached before. For example, for a phosphoric acid tank, the phosphoric acid solution therein is used for the first time and has not been leached. The etching solution does not contain silica generated by leaching, thereby eliminating interference factors. In addition, since the silicon oxide etching rate of the original acid tank is relatively high, for example, it is usually When testing different running quantities, 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 other process menus derived from 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 larger the thickness of the film layer to be etched. Under the same running volume, more material is etched, 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, less material is etched, 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 bath silicon oxide etching rate ER, the corresponding acid bath silicon oxide etching rate of each group of products to be shipped is estimated to be 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 being 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 budgeting 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 last 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 last batch of goods and the corresponding last batch of goods.

[0066] As an example, after the small acid change, the silicon oxide etching rate of the acid bath 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 performing a small acid change, return to the etching rate budgeting step to perform a new round of judgment and selection, so that the acid tank etching rate is always stable near the target etching rate.

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

[0069] (1) Establish the relationship curve between the phosphate bath silicon oxide etching rate and the running volume of 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 shipped, estimate the silicon oxide etching rate in the phosphate bath after the shipment of each batch of products to be shipped 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, a group of products 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 greatly, the product group with the smallest absolute value of |a-2.5| is preferentially selected for running goods;

[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 ER will increase by about 0.3.

[0075] It should be pointed out 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 reference relationship curve between the running volume and the silicon oxide etching rate in the phosphoric acid tank is established, and the relationship curve formula of the acid tank silicon oxide etching rate corresponding to each of the other process menus with the running volume is derived according to the reference relationship curve formula, 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 arranging, and finally the etching rate balance is achieved. In other words, through 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 budgeting 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 with the change of the running quantity, before running, for multiple groups of products to be run online, according to the type and running quantity of each group of products to be run, based on the corresponding relationship curve and the current acid tank silicon oxide etching rate, the corresponding etching rate of each group of products to be run after running is budgeted, and then after the last group of products is completed, according to the range of the current acid tank silicon oxide etching rate, a group of products is selected from the multiple groups of products to be run online to run or change the acid, and finally the acid tank etching rate is stabilized near the target etching rate. In the acid tank wet etching method of the present invention, even if different types of products run over the acid tank, the acid tank etching rate can still remain stable, and 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 in 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 familiar with 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 a person of ordinary skill in the art without departing from the spirit and technical concept disclosed by the present invention shall still 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: Steps for establishing the relationship curve: for different types of products, establish the relationship curve between the acid tank silicon oxide etching rate and the running 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 shipping 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 of each group of products to be shipped after shipping; The first judgment step: judging whether ER satisfies M<ER<N. If so, a group of products to be shipped online is randomly selected for shipping. If not, the second judgment step is performed, wherein 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: judge whether ER satisfies S<ER≤M. If so, a group of products with a>S and the smallest absolute value of |aT| are selected from all the online products to be sold. When all the online products to be sold do not satisfy a>S, a group of products with a≤S and the smallest absolute value of |aT| are selected for selling. If not, the third judgment step is performed, wherein 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 tank wet etching method according to claim 1, characterized in that: The acid tank comprises a phosphoric acid tank, and the target etching film layer of the product comprises 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, characterized in that: The relationship curve is a linear relationship curve and has a negative slope.

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

5. The acid tank wet etching method according to claim 4, characterized in that: The relationship curve establishing step comprises: Select a process menu from multiple process menus, and measure the acid tank silicon oxide etching rate after different running 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 amount, Y is the acid tank silicon oxide etching rate after the run is completed, -A is the slope, and B is the acid tank silicon oxide etching rate when the run 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 and the change in running volume are derived.

6. The acid tank wet etching method according to claim 5, characterized in that: The relationship curve formula of the etching rate corresponding to other process menus derived according to the benchmark relationship curve formula changes with the running volume is Y=-(Ae / d)X+B, wherein 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, characterized in that: In the etching rate estimation step, based on the corresponding relationship curve and the current acid bath silicon oxide etching rate ER, the corresponding acid bath silicon oxide etching rate of each group of products to be shipped is estimated after shipping. 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 being sold, -A i is the slope of the relationship curve corresponding to the group of products to be shipped, Q i The calculated sales volume of a group of products to be shipped.

8. The acid tank wet etching method according to claim 1, characterized in that: 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, characterized in that: After the small acid change, the silicon oxide etching rate of the acid bath returns to the range of M to N.

10. The acid tank wet etching method according to claim 1, characterized in that: After a group of products are selected from all products to be shipped online for shipping or after a small acid change, the process returns to the etching rate budgeting step.

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