A method of treating an etching liquid

Abstract

The application discloses a method for processing etching liquid, which is applied to the field of semiconductor manufacturing. In the process of etching the surface of a wafer by using etching liquid, a target parameter related to the Si concentration in the etching liquid is monitored; and the water supply amount of the etching liquid is adjusted according to the monitored target parameter. By adjusting the water supply amount of the etching liquid, the etching rate change caused by Si deposition is controlled, so that the same pattern profile is formed in etching, cost is saved, and production efficiency is improved.

Description

Technical Field

[0001] This invention relates to the field of semiconductor manufacturing, and more particularly to a method for treating etching solutions. Background Technology

[0002] Patterning using a dual film of silicon nitride (SiN) and oxide is frequently used in chip manufacturing. The patterning process employs a chemical wet etching process using phosphoric acid solution (H3PO4) as the etchant. Phosphoric acid solution (H3PO4) has a high selectivity ratio (30–100:1) between SiN and oxide. A representative process is STI (Shallow Trench Isolation), which is widely used in the manufacture of memory, logic circuits, and other semiconductor products.

[0003] In chemical wet etching processes using phosphoric acid solution as the etchant, the accumulation of Si reactants generated after SiN film etching within the phosphoric acid solution inhibits the oxidative corrosion reaction of the phosphoric acid solution. Therefore, as the number of wafers processed increases, the resulting pattern profile gradually changes. Existing technology controls the change in pattern profile within a certain range by replacing the etchant after Si deposition reaches a fixed amount. However, replacing the etchant increases material costs and prolongs production time. Summary of the Invention

[0004] In view of the above-mentioned technical problems in the prior art, embodiments of the present invention provide a method for treating corrosive liquids, comprising:

[0005] During the etching process of the wafer surface using an etchant, target parameters related to the Si concentration in the etchant are monitored.

[0006] Adjust the water supply to the corrosive solution based on the monitored target parameters.

[0007] Optionally, the target parameter can be any of the following: the accumulated Si concentration in the etching solution, the etching rate, the etched pattern profile, and the number of wafers processed.

[0008] Optionally, monitoring the target parameter related to the Si concentration in the etching solution includes: detecting the current Si concentration of the etching solution using a silicon concentration meter;

[0009] The step of adjusting the water supply to the corrosive solution based on the monitored target parameters includes:

[0010] Determine whether the current Si concentration of the corrosion solution exceeds the target concentration range. If so, adjust the water supply to the corrosion solution based on the current Si concentration.

[0011] Optionally, adjusting the water supply to the etching solution based on the current Si concentration includes: if the current Si concentration is higher than the target concentration range, reducing the water supply to the etching solution based on the current Si concentration; if the current Si concentration is lower than the target concentration range, increasing the water supply to the etching solution based on the current Si concentration.

[0012] Optionally, monitoring the target parameter related to the Si concentration in the etching solution includes: detecting the current Si concentration in the etching solution using a silicon concentration meter, and determining the current etching rate corresponding to the current Si concentration based on the correspondence between the etching rate and the Si concentration in the sulfuric acid etching solution;

[0013] The step of adjusting the water supply to the corrosive solution based on the monitored target parameters includes:

[0014] Determine whether the current etching rate exceeds the target etching rate range. If so, adjust the water supply to the etching solution according to the current etching rate.

[0015] Optionally, adjusting the water supply to the etching solution based on the current etching rate includes: reducing the water supply to the etching solution if the current etching rate is higher than the target etching rate range; and increasing the water supply to the etching solution if the current etching rate is lower than the target etching rate range.

[0016] Optionally, monitoring the target parameter related to the Si concentration in the etching solution includes: monitoring the current number of wafers being etched by the etching solution on the wafer surface; adjusting the water supply to the etching solution based on the monitored target parameter includes: determining the target water supply corresponding to the current number of wafers being etched based on the correspondence between the number of wafers being etched and the water supply; and adjusting the water supply to the etching solution to the target water supply during the etching process of the current wafer surface.

[0017] Optionally, the water content in the phosphoric acid corrosion solution can be adjusted to be in the range of 10% to 20%.

[0018] One or more technical solutions provided in the embodiments of the present invention achieve at least the following technical effects or advantages:

[0019] In this embodiment of the invention, during the etching process of a wafer surface using an etchant, a target parameter related to the Si concentration in the etchant is monitored. The water supply to the etchant is adjusted based on the monitored target parameter to address the etching rate variation caused by the accumulation of Si reactants in the etchant. This ensures that the etching rate for each wafer remains stable within a certain range, resulting in identical etched patterns without the need to replace the etchant. Therefore, this method saves costs and improves production efficiency while ensuring semiconductor product quality. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0021] Figure 1 This is a flowchart illustrating the method for treating etching solution during wafer fabrication in an embodiment of the present invention.

[0022] Figure 2 This is a schematic diagram illustrating the relationship between etching rate and Si concentration in an embodiment of the present invention;

[0023] Figure 3 for Figure 2 A schematic diagram illustrating the differences between the corresponding graphic outlines. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Unless otherwise specified, the embodiments of the present invention and the technical features thereof can be combined with each other. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0025] This specification provides an embodiment of a method for handling etchant during wafer fabrication, specifically applied to a patterning process using a SiN / Oxide dual-film. In the patterned structure of the SiN / Oxide dual-film, a chemical wet etching process is used, employing the SiN film as a sacrificial film to form an Oxide pattern. (Reference) Figure 1 As shown, the method includes the following steps:

[0026] S10. During the etching process of the wafer surface using the etching solution, monitor the target parameters related to the Si concentration in the etching solution; S20. Adjust the water supply to the etching solution according to the monitored target parameters.

[0027] Specifically, the etching solution can be phosphoric acid solution or hydrofluoric acid, etc. The etching process using H3PO4 to etch the wafer surface involves temperatures above 160 degrees Celsius and processing times ranging from several minutes to tens of minutes. This process needs to be performed in batch processing equipment. Therefore, during the etching process, the Si reactants generated after etching the SiN film accumulate in the etching solution as the number of wafers processed increases. The increasing amount of Si reactants deposited in the etching solution inhibits the etching rate.

[0028] refer to Figure 2 As shown, the amount of Si deposited in the etching solution (A, A1, A2) will cause differences in the etching rate (B, B1, B2), which in turn leads to... Figure 3 The differences between the outlines of the figures shown.

[0029] In this embodiment of the invention, the water supply of the etching solution is adjusted in steps S10 to S20 to address the changes in etching rate caused by the accumulation of Si reactants in the etching solution, thereby stabilizing the etching rate within a certain range and ensuring that the etched pattern outline is consistent.

[0030] In step S10, the target parameters related to the Si concentration in the etching solution are monitored. These parameters may include the accumulated Si concentration, etching rate, pattern profile, or number of wafers processed in the etching solution. The water supplied to the etching solution in the process tank may specifically be DIW (Deionized Water).

[0031] Depending on the target parameters being monitored, steps S10 to S20 can be implemented using either hardware or software methods. The following describes different implementation methods for steps S10 to S20 based on the different target parameters being monitored:

[0032] Implementation Method 1:

[0033] Step S10 specifically refers to step A10: detecting the current Si concentration of the etching solution using a silicon concentration meter. Specifically, the Si concentration of the etching solution within the process bath is confirmed in real-time using a silicon concentration meter.

[0034] Step S20 includes: Step A201, determining whether the current Si concentration of the etching solution exceeds the target concentration range; Step A202, if so, adjusting the water supply to the etching solution according to the current Si concentration.

[0035] It should be noted that the target concentration range varies depending on the specific composition of the etching solution and needs to be determined according to actual process requirements. Specifically, if the etching solution is an additive-free H3PO4 solution, the target Si concentration range is 100–200 ppm. If Si additives are added to the new etching solution to reduce the etching rate, the corresponding target concentration range is 100 ppm.

[0036] Step A201 specifically involves: if the current Si concentration is higher than the target concentration range, reducing the water supply to the etching solution based on the current Si concentration to decrease the etching rate; if the current Si concentration is lower than the target concentration range, increasing the water supply to the etching solution based on the current Si concentration to increase the etching rate. The increased or decreased water supply can be a change value corresponding to the current Si concentration, or it can be a pre-set fixed value.

[0037] Implementation method one enables the water supply to be adjusted based on the Si concentration of the etching solution in the monitoring process tank, which ensures that each wafer can be processed at a consistent etching rate, thereby forming a consistent pattern profile on different wafers.

[0038] Implementation Method Two:

[0039] Step S10 specifically includes the following steps B101 to B102:

[0040] Step B101: Detect the Si concentration in the etching solution using a silicon concentration meter; specifically, confirm the Si concentration in the process tank in real time using a silicon concentration meter that monitors the Si concentration in the process tank.

[0041] Step B102: Determine the current etching rate corresponding to the current Si concentration based on the correspondence between the etching rate and the Si concentration in the sulfuric acid etching solution.

[0042] refer to Figure 2 As shown, the etching rate decreases continuously as the Si concentration in the sulfuric acid etching solution increases.

[0043] Step S20 specifically includes the following steps B201 to B202:

[0044] Step B201: Determine whether the current etching rate exceeds the target etching rate range.

[0045] Specifically, the target etching rate range varies depending on the oxide film material, and is not specifically limited here. It is set according to the oxide film material in the actual process. Taking TEOS film obtained by CVD as an example, the target etching rate range can be 10 minutes. The etching rate decreases as the water content in the etching solution increases, but the decrease in etching rate is not linear; rather, it resembles a quadratic function curve, eventually approaching "0".

[0046] Step B202: If the current etching rate exceeds the target etching rate range, adjust the water supply to the etching solution according to the current etching rate.

[0047] Step B202 specifically involves: if the current etching rate is higher than the target etching rate range, reducing the water supply to the etchant to decrease the etching rate; if the current etching rate is lower than the target etching rate range, increasing the water supply to the etchant to increase the etching rate. The increased or decreased water supply can be a change corresponding to the current etching rate, or it can be a pre-set fixed value.

[0048] To prevent situations where the silicon concentration meter cannot be used, or where the water supply cannot be adjusted according to the silicon concentration meter, the following software-based implementation method three can be used:

[0049] Step S10 specifically refers to step C10: During the etching process of the etchant on the wafer surface, the current number of wafers being etched by the etchant on the wafer surface is monitored.

[0050] As the number of wafers processed by the etchant increases, the amount of Si reactants deposited in the etchant also increases. Therefore, the Si concentration in the etchant increases with the number of wafers processed. Based on this, the correspondence between the number of wafers processed and the water supply can be predetermined. Therefore, step S20 specifically includes: during the etching process of the wafer surface, determining the target water supply corresponding to the current number of wafers processed based on the correspondence between the number of wafers processed and the water supply; and adjusting the water supply to the etchant to the target water supply during the etching process of the current wafer surface.

[0051] Specifically, the relationship between the number of wafers processed and the water supply can be determined in advance through experiments. This is achieved by calculating the Si concentration generated within the process tank during the etching of a single wafer. Based on the Si concentration generated within the process tank during the etching of a single wafer, and by calculating the Si concentration under different wafer numbers, the etching rate and pattern profile under different wafer numbers can be predicted. A table is then created to display the etching rate under varying wafer numbers and water supply, and this table is used to establish the relationship between the number of wafers processed and the water supply in the system.

[0052] By implementing the third method, the water supply to the phosphoric acid etching solution can be adjusted according to the number of wafers processed, ensuring that each wafer can be processed at a consistent etching rate, thereby forming a consistent pattern profile on different wafers.

[0053] Furthermore, in specific implementation, regardless of which of the above implementation methods is adopted, in order to ensure the process effect, the water content of the phosphoric acid corrosion solution should be maintained in the range of 10-20% by adjusting the water supply to the phosphoric acid corrosion solution.

[0054] The above description does not provide detailed explanations of the technical aspects of each layer's patterning, etching, etc. However, those skilled in the art should understand that various technical means can be used to form layers and regions of the desired shape. Furthermore, to form the same structure, those skilled in the art can also design methods that are not entirely identical to those described above. Additionally, although various embodiments have been described above, this does not mean that the measures in the various embodiments cannot be used advantageously in combination.

[0055] Although preferred embodiments of the invention have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including both the preferred embodiments and all changes and modifications falling within the scope of the invention. Clearly, those skilled in the art can make various alterations and modifications to the invention without departing from its spirit and scope. Thus, if these modifications and modifications of the invention fall within the scope of the claims and their equivalents, the invention is also intended to include these modifications and modifications.

Claims

1. A method for treating corrosive liquids, characterized in that, include: During the etching process of the wafer surface using phosphoric acid etching solution, target parameters related to the Si concentration in the etching solution are monitored. Adjust the water supply to the corrosive solution according to the monitored target parameters; The target parameter that is related to the Si concentration in the etching solution includes: monitoring the number of wafers currently being processed by the etching solution to etch the wafer surface. The step of adjusting the water supply to the corrosive solution based on the monitored target parameters includes: Based on the predetermined correspondence between the number of wafers processed and the water supply, the target water supply corresponding to the current number of wafers processed is determined. The correspondence between the number of wafers processed and the water supply is predetermined as follows: The Si concentration generated in the process tank during etching of a single wafer is calculated; based on the Si concentration generated in the process tank during etching of a single wafer and the number of wafers processed, the Si concentration under different numbers of wafers processed is calculated, and the etching rate and pattern profile under different numbers of wafers processed are predicted; a table is generated through experiments; the table is used to display the etching rate under changes in the number of wafers processed and the water supply; and the correspondence between the number of wafers processed and the water supply is established based on the table. During the etching process on the surface of the wafers of the current number of wafers being processed, the water supply to the etching solution is adjusted to the target water supply.

2. The method as described in claim 1, characterized in that, The target parameters are any one of the following: the accumulated Si concentration in the etching solution, the etching rate, the etched pattern profile, and the number of wafers processed.

3. The method as described in claim 1 or 2, characterized in that, When adjusting the water supply to the phosphoric acid corrosion solution, maintain the water content in the solution within the range of 10% to 20%.

Images