Wet wafer thinning method
By obtaining the correspondence between the cumulative usage time of the etching liquid and the etching speed, and calculating and applying the appropriate etching time for a wet thinning process, the problem of reducing etching speed caused by the increase in the usage time of the etching liquid is solved, and the consistency of wafer thickness is achieved.
Patent Information
- Application Number
- CN202111370342.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2021-11-18
- Publication Date
- 2025-06-06
- Estimated Expiration
- 2041-11-18
AI Technical Summary
In the manufacturing process of semiconductor integrated circuits, the etching speed of the etching liquid decreases with the increase of the use time, resulting in a decrease in the amount of wafer etching at the same etching time, resulting in a large difference in wafer thickness after thinning.
By obtaining the correspondence between the cumulative usage time of the etching liquid and the etching speed, the current etching speed and the preset etching thinning amount are calculated, the required etching time is determined, and the wet thinning process is performed using the etching liquid. Optionally, it is determined whether to replace the etching liquid based on the accumulated usage time.
The consistency of the wet thinning amount of wafer is ensured, and the thickness of the wafer is consistent after thinning is avoided, and the thickness difference caused by the reduction of the etching speed of the etching liquid is avoided.
Smart Images
Figure CN114121638B_ABST
Abstract
Description
Technical Field
[0001] The present application relates to the technical field of semiconductor integrated circuit manufacturing, and in particular to a wafer wet thinning method for improving the consistency of wafer etching amount. Background Art
[0002] Semiconductor integrated circuit manufacturing processes are moving towards thinner wafers, which places more stringent requirements on wafer thickness. In order to make devices have higher thermodynamic consistency and vertical power devices have higher electrical consistency, the requirements for wafer thickness consistency between wafers are becoming increasingly higher.
[0003] However, in the process of thinning the wafer by combining grinding with wet etching, the etching rate of the etching solution on the wafer decreases as the cumulative use time of the etching solution increases, resulting in a decrease in the etching amount of the wafer with the same etching time, resulting in large differences in the thickness of different wafers after thinning. Summary of the invention
[0004] The present application provides a method for wet wafer thinning, which can solve the problem in the related art that the etching speed of the etching solution on the wafer decreases with the increase of the cumulative use time of the etching solution, thereby resulting in a decrease in the etching amount of the wafer with the same etching time, resulting in large differences in the thickness of different wafers after thinning.
[0005] In order to solve the technical problem described in the background technology, the present application provides a wafer wet thinning method, which comprises the following steps performed in sequence:
[0006] Obtaining the corresponding relationship between the cumulative use time variable of the etching solution and the etching speed variable;
[0007] Acquire a current target wafer, and determine a current accumulated usage time of the etching solution when performing a wet thinning process on the current target wafer;
[0008] Based on the current accumulated usage time of the etching solution and the corresponding relationship, determining a current etching speed corresponding to the current accumulated usage time of the etching solution;
[0009] Based on the current etching speed and the preset etching thinning amount, calculating the current etching time of the wet thinning process for the current target wafer;
[0010] The etching solution is used to perform a wet thinning process on the current target wafer with the current etching time.
[0011] Optionally, after the step of using the etching solution to perform a wet thinning process on the current target wafer with the current etching time is completed, the following is further performed:
[0012] The value of the variable of the accumulated usage time of the etching solution is increased;
[0013] Whether to replace the etching solution is determined based on whether the increased value of the accumulated usage time variable of the etching solution is greater than the preset accumulated usage time.
[0014] Optionally, the step of determining whether to replace the etching solution based on judging whether the increased value of the accumulated usage time variable of the etching solution is greater than a preset accumulated usage time comprises:
[0015] When the increased value of the accumulated usage time variable of the etching solution is greater than the preset accumulated usage time, it is determined to replace the etching solution;
[0016] The value of the variable of the accumulated usage time of the etching solution is reset to zero, which is used as the next accumulated usage time of the etching solution to perform a wet thinning process on the next target wafer.
[0017] Optionally, the step of determining whether to replace the etching solution based on judging whether the increased value of the accumulated usage time variable of the etching solution is greater than a preset accumulated usage time comprises:
[0018] When the increased value of the accumulated usage time variable of the etching solution is less than or equal to the preset accumulated usage time, the increased value of the accumulated usage time variable of the etching solution is used as the next accumulated usage time of the etching solution, and the wet thinning process is performed on the next target wafer.
[0019] Optionally, before the step of obtaining the corresponding relationship between the cumulative use time variable of the etching solution and the etching speed variable is performed, the following steps are further performed:
[0020] The corresponding relationship between the cumulative use time variable of the etching solution and the etching speed variable is predetermined and stored.
[0021] Optionally, the step of calculating the current etching time of the wet thinning process for the current target wafer based on the current etching speed and the preset etching thinning amount includes:
[0022] Obtaining the current etching speed and the preset etching thinning amount;
[0023] Based on the current etching speed and the preset etching thinning amount, and the formula: etching time = etching thinning amount / etching speed, the current etching time of the wet thinning process for the current target wafer is calculated.
[0024] Optionally, the etching thinning amount is a pre-stored constant.
[0025] The technical solution of the present application includes at least the following advantages: the present application uses a characteristic of an etching solution, that is, there is a specific corresponding relationship between the variable of the cumulative use time of the etching solution and the variable of the etching speed, so that the etching solution is used for different target wafers at different cumulative use times, so that the final etching thinning amount is the same, that is, equal to the preset etching thinning amount, so that the wet thinning degree of several wafers can be consistent, and then the thickness of the wafers after thinning can be consistent. Avoid the problem that the etching speed of the etching solution on the wafer decreases with the increase of the cumulative use time of the etching solution, resulting in large differences in the thickness of different wafers after thinning BRIEF DESCRIPTION OF THE DRAWINGS
[0026] In order to more clearly illustrate the specific implementation methods of the present application or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.
[0027] Figure 1 A flow chart of a wafer wet thinning method provided by an embodiment of the present application is shown;
[0028] Figure 2 The flowchart of the wafer wet thinning method provided by the present application is shown;
[0029] Figure 3 A schematic flow chart of an embodiment of step S17 is shown. DETAILED DESCRIPTION
[0030] The following will be combined with the accompanying drawings to clearly and completely describe the technical solutions in this application. Obviously, the described embodiments are part of the embodiments of this application, not all of them. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.
[0031] In the description of the present application, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present application. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.
[0032] In the description of this application, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, it can also be the internal connection of two components, it can be a wireless connection, or it can be a wired connection. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.
[0033] In addition, the technical features involved in the different embodiments of the present application described below can be combined with each other as long as they do not conflict with each other.
[0034] Figure 1 A flow chart of a wafer wet thinning method provided in one embodiment of the present application is shown.
[0035] from Figure 1 It can be seen that the wafer wet thinning method includes the following steps performed in sequence:
[0036] Step S11: Obtaining the corresponding relationship between the cumulative usage time variable of the etching solution and the etching speed variable.
[0037] It should be noted that, usually corresponding to an etching solution, the value of its etching speed variable decreases as the value of its cumulative usage time variable increases. Different etching solutions have different corresponding relationships between the usage time variable and the etching speed variable. Therefore, it is necessary to test the etching solution used in the wafer wet thinning method in advance to determine and store the corresponding relationship between the cumulative usage time variable of the etching solution and the etching speed variable.
[0038] The corresponding relationship is a functional corresponding relationship between the variable of the accumulated use time of the etching solution and the variable of the etching speed, which can be expressed by a table or a formula.
[0039] Step S12: Acquire the current target wafer, and determine the current accumulated usage time of the etching solution when performing a wet thinning process on the current target wafer.
[0040] When performing the wafer wet thinning method, the same wafer wet thinning process is performed on a plurality of target wafers in sequence.
[0041] When the wafer wet thinning method is performed on a current target wafer among a plurality of target wafers, it is necessary to first determine the current accumulated usage time of the etching solution when the wet thinning process is performed on the current target wafer.
[0042] Among them, the current cumulative usage time of the etching solution is: the total etching operation time from the time when the etching solution is replaced to the time when the wet thinning process is performed on the current target wafer.
[0043] Step S13: Based on the current accumulated usage time of the etching solution and the corresponding relationship, determine a current etching speed corresponding to the current accumulated usage time of the etching solution.
[0044] When it is determined in step S12 that the wafer wet thinning method is to be performed on the current target wafer, the current accumulated usage time of the etching solution is then combined with the correspondence between the accumulated usage time variable of the etching solution determined in step S11 and the etching speed variable, so as to determine the current etching speed corresponding to the current accumulated usage time of the etching solution.
[0045] Step S14: Based on the current etching speed and the preset etching thinning amount, the current etching time of the wet thinning process for the current target wafer is calculated.
[0046] The preset etching thinning amount can be set and stored in advance according to the requirements. Optionally, the preset etching thinning amount is a constant, so that the wet thinning degree of a plurality of wafers can be consistent, and thus the thickness of the wafers after thinning can be consistent.
[0047] Optionally, the current etching speed determined in step S13 can be first obtained, and combined with the preset etching thinning amount, the current etching time of the wet thinning process for the current target wafer can be calculated through the formula: etching time = etching thinning amount / etching speed.
[0048] Step S15: using the etching solution and the current etching time to perform a wet thinning process on the current target wafer.
[0049] This embodiment uses a characteristic of an etching solution, that is, there is a specific corresponding relationship between the variable of the cumulative use time of the etching solution and the variable of the etching speed, so that the etching solution is used for different target wafers at different cumulative use times, so that the final etching thinning amount is the same, that is, equal to the preset etching thinning amount, so that the wet thinning degree of several wafers can be consistent, and then the thickness of the wafers after thinning can be consistent. Avoid the problem that the etching speed of the etching solution on the wafer decreases with the increase of the cumulative use time of the etching solution, resulting in large differences in the thickness of different wafers after thinning.
[0050] In addition, the subsequent target wafer is also subjected to the wafer wet thinning method according to the above steps S11 to S15.
[0051] In order to facilitate the subsequent target wafer to perform the wafer wet thinning method, Figure 2 The flow chart of the wafer wet thinning method provided by the present application is shown. Figure 2 It can be seen that after step S15 is completed, it also includes:
[0052] Step S16: increasing the value of the variable of the accumulated usage time of the etching solution.
[0053] Step S17: Determine whether to replace the etching solution based on whether the increased value of the accumulated usage time variable of the etching solution is greater than the preset accumulated usage time.
[0054] in, Figure 3 The schematic diagram of the embodiment flow of step S17 is shown. Figure 3 It can be seen that based on the judgment result of step S17, step S17 includes:
[0055] Step S171: When the increased value of the variable of the accumulated usage time of the etching solution is greater than the preset accumulated usage time, it is determined to replace the etching solution.
[0056] Step S172: reset the value of the variable of the accumulated usage time of the etching solution to zero, and use it as the next accumulated usage time of the etching solution, and perform the wet thinning process described in steps S11 to S17 on the next target wafer.
[0057] Or the step S17 includes:
[0058] Step S173: When the increased value of the variable of the accumulated usage time of the etching solution is less than or equal to the preset accumulated usage time, the increased value of the variable of the accumulated usage time of the etching solution is used as the next accumulated usage time of the etching solution, and the wet thinning process as described in steps S11 to S17 is performed on the next target wafer.
[0059] Obviously, the above embodiments are merely examples for the purpose of clear explanation, and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived therefrom are still within the scope of protection created by this application.
Claims
1. A wafer wet thinning method, It is characterized in that The wafer wet thinning method comprises the following steps performed in sequence: Obtaining a correspondence between a pre-stored cumulative usage time variable of the etching solution and an etching speed variable; Acquire a current target wafer, and determine a current accumulated usage time of the etching solution when performing a wet thinning process on the current target wafer; Based on the current accumulated usage time of the etching solution and the corresponding relationship, determining a current etching speed corresponding to the current accumulated usage time of the etching solution; Based on the current etching speed and the preset etching thinning amount, calculating the current etching time of the wet thinning process for the current target wafer; The etching solution is used to perform a wet thinning process on the current target wafer with the current etching time.
2. The wafer wet thinning method according to claim 1, It is characterized in that After the step of using the etching solution and the current etching time to perform a wet thinning process on the current target wafer is completed, the following is further performed: The value of the variable of the accumulated usage time of the etching solution is increased; Whether to replace the etching solution is determined based on whether the increased value of the accumulated usage time variable of the etching solution is greater than the preset accumulated usage time.
3. The wafer wet thinning method according to claim 2, It is characterized in that The step of determining whether to replace the etching solution based on judging whether the increased value of the accumulated usage time variable of the etching solution is greater than the preset accumulated usage time comprises: When the increased value of the accumulated usage time variable of the etching solution is greater than the preset accumulated usage time, it is determined to replace the etching solution; The value of the variable of the accumulated usage time of the etching solution is reset to zero, which is used as the next accumulated usage time of the etching solution to perform a wet thinning process on the next target wafer.
4. The wafer wet thinning method according to claim 2, It is characterized in that The step of determining whether to replace the etching solution based on judging whether the increased value of the accumulated usage time variable of the etching solution is greater than the preset accumulated usage time comprises: When the increased value of the accumulated usage time variable of the etching solution is less than or equal to the preset accumulated usage time, the increased value of the accumulated usage time variable of the etching solution is used as the next accumulated usage time of the etching solution, and the wet thinning process is performed on the next target wafer.
5. The wafer wet thinning method according to claim 1, It is characterized in that Before the step of obtaining the corresponding relationship between the cumulative use time variable of the etching solution and the etching speed variable is performed, the following steps are also performed: The corresponding relationship between the cumulative use time variable of the etching solution and the etching speed variable is predetermined and stored.
6. The wafer wet thinning method according to claim 1, It is characterized in that The step of calculating the current etching time of the wet thinning process for the current target wafer based on the current etching speed and the preset etching thinning amount includes: Obtaining the current etching speed and the preset etching thinning amount; Based on the current etching speed and the preset etching thinning amount, and the formula: etching time = etching thinning amount / etching speed, the current etching time of the wet thinning process for the current target wafer is calculated.
7. The wafer wet thinning method according to claim 1 or 6, It is characterized in that The etching thinning amount is a pre-stored constant.
Citation Information
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