Wet etching equipment and wet etching method
By dividing the silicon wafer etching area into concentric ring regions in a single-wafer wet etching apparatus and adjusting the etching time, swing arm position, and local heating temperature according to film thickness distribution data, the etching uniformity problem caused by thickness differences in local areas of the silicon wafer is solved, achieving higher etching precision and consistency.
Patent Information
- Application Number
- CN202511290075.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-09-10
- Publication Date
- 2025-12-16
AI Technical Summary
Existing single-wafer wet etching equipment has difficulty eliminating thickness differences in local areas of silicon wafers during the etching process, resulting in insufficient etching uniformity and failing to meet the etching requirements for thickness differences in local areas of silicon wafer surface.
By dividing the silicon wafer etching area into multiple concentric ring regions, and adjusting the etching time, swing arm position, and local heating temperature according to film thickness distribution data, precise control is achieved. This includes using a heated clamp to hold the edge of the silicon wafer and rotate it, the swing arm to spray etchant, and the coordinated action of a control device to achieve precise etching.
It significantly improves the uniformity of wet etching, enhances the precision and consistency of etching, and overcomes the shortcomings of existing technologies that rely solely on ring-based control.
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Figure CN121149048A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application belongs to the field of semiconductor wet processing, and particularly relates to a wet etching equipment and a wet etching method for improving etching uniformity. BACKGROUND
[0002] The single-wafer wet processing equipment is a key process equipment in semiconductor manufacturing, which is mainly used for wet cleaning and etching of silicon wafers. The single-wafer wet processing equipment can better control the cleaning product quality and process parameters, reduce the cross-contamination between silicon wafers, and improve the consistency and reliability of products. In the current single-wafer wet processing equipment, the heating clamp is mainly used for the drying step of the silicon wafer. By clamping the silicon wafer and rotating with the silicon wafer, the silicon wafer is directly heated to improve the temperature of isopropyl alcohol (IPA) and enhance the drying capacity of isopropyl alcohol. In addition, for the wet etching uniformity, the current advanced process control (APC) mainly relies on the thickness data of the silicon wafer in the previous process to divide the swing arm motion trajectory into outer, middle and inner rings, and to compensate for the thickness difference by synchronously adjusting the etching time. However, this method only relies on the ring control, and it is difficult to eliminate the thickness difference of the local area of the silicon wafer, so the optimization effect on the etching uniformity is limited, and it cannot meet the etching requirement of the thickness difference of the local area of the silicon wafer surface. SUMMARY
[0003] The present application aims to provide a wet etching equipment and a wet etching method, which can realize precise etching and improve the uniformity of wet etching.
[0004] To achieve the above-mentioned purpose, the present application provides a wet etching equipment, which comprises a swing arm, a heating clamp, and a control device.
[0005] The heating clamp is used to clamp the edge of the silicon wafer, and can drive the silicon wafer to rotate around its central axis after being driven;
[0006] The swing arm is used to be arranged above the silicon wafer to spray etchant;
[0007] The control device is configured to perform the following steps:
[0008] The etching area of the silicon wafer is divided into a plurality of concentric ring-shaped areas;
[0009] According to the silicon wafer film thickness distribution data, the silicon wafer film thickness mean value, the film thickness difference of the plurality of ring-shaped areas, and the film thickness difference of the local area of the silicon wafer are determined;
[0010] According to the target film thickness of the silicon wafer, the silicon wafer film thickness mean value, and the preset etching rate, the global average etching time is determined;
[0011] According to the film thickness difference of the plurality of ring-shaped areas and the global average etching time, the etching time gear of the plurality of ring-shaped areas is determined.
[0012] determining a heating temperature of the local area of the silicon wafer according to the film thickness difference of the local area of the silicon wafer;
[0013] adjusting the position of the swing arm, and controlling the swing arm to spray the etching agent to the target annular area according to the set etching time level, and synchronously controlling the heating clamp to heat the local area of the silicon wafer according to the set heating temperature.
[0014] In some embodiments, the control device comprises:
[0015] a swing arm position control module for adjusting the position of the swing arm;
[0016] an etching time control module for controlling the etching time of the swing arm;
[0017] a temperature control module for controlling the heating temperature of the heating clamp; and
[0018] a calculation module for determining the global average etching time, the etching time level and the heating temperature.
[0019] In some embodiments, the calculation unit comprises:
[0020] a film thickness difference analysis unit for determining the film thickness mean value of the silicon wafer, the film thickness difference of the annular areas and the film thickness difference of the local area of the silicon wafer according to the film thickness distribution data of the silicon wafer;
[0021] a region division unit for dividing the etching region of the silicon wafer into a plurality of concentric annular areas;
[0022] a target value calculation unit for calculating the global average etching time according to the target film thickness of the silicon wafer, the film thickness mean value of the silicon wafer and the preset etching rate;
[0023] a time matching unit for determining the etching time levels of the annular areas according to the global average etching time and the film thickness difference of the annular areas;
[0024] a temperature compensation unit for determining the heating temperature of the local area of the silicon wafer according to the film thickness difference of the local area of the silicon wafer.
[0025] In some embodiments, the heating clamp comprises a heating base, a clamp and a heating source; the heating base is located below the silicon wafer and can drive the silicon wafer to rotate after being driven; the clamp and the heating source are both installed on the heating base; the clamp is used for clamping the edge of the silicon wafer; the heating source is located between the silicon wafer and the heating base and is used for heating the local area of the silicon wafer.
[0026] In some embodiments, the heating source comprises a plurality of LED light sources, which are evenly distributed on the heating base and form a plurality of independent heating zones, each of which corresponds to a local area on the silicon wafer.
[0027] In some embodiments, the plurality of LED light sources are distributed in a grid shape, each grid constituting a heating zone.
[0028] In some embodiments, the number of LED light sources is 500-1500.
[0029] In some embodiments, the heating temperature of the heating clamp is 23-100°C, and / or the rotation speed of the heating clamp is 200-1200 rpm.
[0030] To achieve the above-mentioned purposes, the application also provides a wet etching method, which is executed based on any one of the wet etching devices, and the wet etching method comprises:
[0031] Dividing the etching area of the silicon wafer into a plurality of concentric ring-shaped areas;
[0032] According to the film thickness distribution data of the silicon wafer, determining the film thickness average value, the film thickness difference of the plurality of ring-shaped areas, and the film thickness difference of the local area of the silicon wafer;
[0033] According to the target film thickness of the silicon wafer, the film thickness average value of the silicon wafer, and the preset etching rate, determining the global average etching time;
[0034] According to the film thickness difference of the plurality of ring-shaped areas and the global average etching time, determining the etching time grade of the plurality of ring-shaped areas;
[0035] According to the film thickness difference of the local area of the silicon wafer, determining the heating temperature of the local area of the silicon wafer;
[0036] Adjusting the position of the swing arm and controlling the swing arm to spray the etchant to the target ring-shaped area according to the set etching time grade, and synchronously controlling the heating clamp to heat the local area of the silicon wafer according to the set heating temperature.
[0037] In some embodiments, the step of determining the etching time grade of the plurality of ring-shaped areas comprises:
[0038] When the film thickness average value of the ring-shaped area is greater than the global film thickness average value, increasing the etching time on the basis of the global average etching time and taking it as the etching time grade required by the target ring-shaped area;
[0039] When the film thickness average value of the ring-shaped area is less than the global film thickness average value, reducing the etching time on the basis of the global average etching time and taking it as the etching time grade required by the target ring-shaped area.
[0040] When the film thickness average of the annular region equals the global film thickness average, the global average etching time is taken as the etching time grade required by the target annular region.
[0041] As described above, the present application provides a wet etching device, comprising: a swing arm; a heating clamp; and a control device; the heating clamp is used for clamping the edge of a silicon wafer and can drive the silicon wafer to rotate around its central axis after being driven; the swing arm is used for being arranged above the silicon wafer to spray etchant; the control device is configured to perform the following steps, comprising: dividing the etching region of the silicon wafer into a plurality of concentric annular regions; determining the film thickness average of the silicon wafer, the film thickness difference of a plurality of the annular regions and the film thickness difference of the local region of the silicon wafer according to the film thickness distribution data of the silicon wafer; determining the global average etching time according to the target film thickness of the silicon wafer, the film thickness average of the silicon wafer and the preset etching rate; determining the etching time grade of a plurality of the annular regions according to the film thickness difference of a plurality of the annular regions and the global average etching time; determining the heating temperature of the local region of the silicon wafer according to the film thickness difference of the local region of the silicon wafer; adjusting the position of the swing arm and controlling the swing arm to spray etchant to the target annular region according to the set etching time grade, and synchronously controlling the heating clamp to heat the local region of the silicon wafer according to the set heating temperature. In this way, the present application can overcome the defects of the prior art that only relies on the division control and cannot eliminate the thickness difference of the local region of the silicon wafer by etching time, swing arm position and local region temperature compensation, thereby improving the wet etching effect and improving the uniformity of the wet etching.
[0042] Here, since the wet etching method provided by the present application belongs to the same inventive concept as the wet etching device provided by the present application, the wet etching method provided by the present application at least has all the beneficial effects of the wet etching device provided by the present application, and specific reference can be made to the related description of the beneficial effects of the wet etching device provided by the present application in the foregoing, so the beneficial effects of the wet etching method provided by the present application will not be described one by one here. BRIEF DESCRIPTION OF DRAWINGS
[0043] Those skilled in the art will understand that the provided drawings are for better understanding of the present application and do not constitute any limitation on the scope of the present application. Among them:
[0044] Figure 1 A structural schematic view of a heating clamp provided by an embodiment of the present application for clamping the edge of a silicon wafer and heating the silicon wafer below the silicon wafer;
[0045] Figure 2Figure 1 is a schematic diagram showing the division of a silicon wafer etching area into multiple concentric ring areas and the measurement of the silicon wafer film thickness distribution data according to an embodiment of the present application. The swing arm is positioned at the outer circle of the silicon wafer to spray etchant to improve the etching uniformity of the outer circle. Each grid represents a local area on the silicon wafer. The number at each local area represents the film thickness value (in angstroms) of the silicon wafer.
[0046] Figure 3 Figure 2 is a schematic diagram showing the division of a silicon wafer etching area into multiple concentric ring areas and the setting of the silicon wafer heating temperature distribution data according to an embodiment of the present application. The swing arm is positioned at the outer circle of the silicon wafer to spray etchant to improve the etching uniformity of the outer circle. Each grid represents a local area on the silicon wafer. The number at each local area represents the required heating temperature (in degrees Celsius) for compensation. The arrow represents the rotation direction of the silicon wafer.
[0047] Figure 4 Figure 3 is a schematic diagram showing the one-to-one correspondence between the heating temperature distribution and the local area film thickness distribution according to an embodiment of the present application.
[0048] Legend of reference numerals:
[0049] 100 - heating fixture, 101 - heating base, 102 - clamp, 103 - heating source, 104 - LED light source, 200 - silicon wafer, 210 - inner circle, 220 - middle circle, 230 - outer circle, 300 - swing arm, 400 - etchant. DETAILED DESCRIPTION
[0050] The present application is described and explained with additional specificity and detail through the use of the accompanying drawings in which:
[0051] In addition, each of the embodiments described below has one or more technical features, but this does not mean that all technical features in any embodiment must be implemented at the same time, or only one or more technical features in different embodiments can be implemented separately. In other words, under the premise of being possible, those skilled in the art can selectively implement some or all of the technical features in any embodiment, or selectively implement a combination of some or all of the technical features in multiple embodiments, according to the disclosure of the present application, and according to the design specifications or implementation needs, thereby increasing the flexibility of the implementation of the present application.
[0052] As used in this specification, the singular forms "a," "an" and "the" include plural referents unless the content clearly dictates otherwise. As used in this specification, the term "or" is generally employed in its sense of "and / or" unless the content clearly dictates otherwise, and the terms "mounting," "connected," and "connection" should be construed broadly, for example, as fixedly connected, as detachably connected, or as integrally connected. It can be a mechanical connection, it can be a direct connection, or it can be an indirect connection through an intermediate medium, it can be an internal connection of two elements or an interaction relationship between two elements. The relationship terms such as "first", "second" and the like are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between the entities or operations, nor indicate or imply relative importance or implicitly indicate the number of technical features indicated. It should be understood that the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "axial", "radial", "circumferential" and the like indicate the orientation or positional relationship 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, and therefore cannot be understood as limiting the present application. The specific meaning of the above terms in the present application can be understood by those skilled in the art according to the specific circumstances.
[0053] Figure 1 A structural schematic diagram of a heating clamp provided by an embodiment of the present application is shown, which clamps the edge of a silicon wafer and heats the silicon wafer below the silicon wafer, Figure 2 A schematic diagram of dividing the etching area of a silicon wafer into multiple concentric ring-shaped areas and measuring the film thickness distribution data of the silicon wafer is shown, Figure 3A diagram for dividing a silicon wafer etching area into multiple concentric ring areas and setting a silicon wafer heating temperature distribution data is shown.
[0054] As shown in Figure 1 , the present application provides a wet etching device, which comprises a heating clamp 100, which can not only clamp the edge of a silicon wafer 200, but also drive the silicon wafer 200 to rotate around its own central axis. The heating clamp 100 can also heat the silicon wafer 200. The heating of the silicon wafer 200 helps to improve the etching uniformity and efficiency, and the heating can also improve the drying capacity of the silicon wafer 200.
[0055] As shown in Figure 2 and Figure 3 , the wet etching device further comprises a swing arm 300, which is arranged above the silicon wafer 200 to spray etchant 400 (see Figure 4 ).
[0056] Those skilled in the art should know that the wet etching device further comprises a reaction chamber, and the swing arm 300 and the heating clamp 100 are arranged in the reaction chamber. The swing arm 300 can generally reciprocate and is installed with a nozzle to spray the etchant 400. Since the present application does not involve improvement of the structure of the swing arm 300, it will not be described in detail.
[0057] The wet etching device further comprises a control device for automatic operation control, for example, for controlling the etching time, etchant concentration, heating temperature, swing arm position, etc.
[0058] In the present embodiment, the control device is configured to perform the following steps:
[0059] Step S1, dividing the etching area of the silicon wafer 200 into multiple concentric ring areas;
[0060] Step S2, determining the average film thickness of the silicon wafer 200, the film thickness difference of the multiple ring areas, and the film thickness difference of the local area of the silicon wafer 200 according to the film thickness distribution data of the silicon wafer 200;
[0061] Step S3, determining the global average etching time according to the target film thickness of the silicon wafer 200, the average film thickness of the silicon wafer 200, and the preset etching rate;
[0062] Step S4, determining the etching time interval (i.e. the actual etching time) of the multiple ring areas according to the film thickness difference of the multiple ring areas and the global average etching time;
[0063] Step S5, determining the heating temperature of the local area of the silicon wafer 200 according to the film thickness difference of the local area of the silicon wafer 200;
[0064] Step S6, adjust the position of the swing arm 300, and control the swing arm 300 to spray the etchant to the target annular area according to the set etching time interval, and control the heating clamp 100 to heat the local area of the silicon wafer 200 according to the set heating temperature, that is, to heat all local areas of the silicon wafer 200 at the same time.
[0065] It should be noted that the above average silicon wafer film thickness refers to the average film thickness of the entire silicon wafer, that is, the average of the silicon wafer film thickness before; the target film thickness of the silicon wafer refers to the film thickness value that the etching wants to reach; the film thickness of each annular area refers to the average film thickness of all local areas in the annular area; the film thickness difference of multiple annular areas refers to the difference between the film thickness of each annular area and the average film thickness of the silicon wafer; the film thickness difference of the local area refers to the difference between the film thickness of the local area and the average film thickness of the silicon wafer.
[0066] Therefore, the difference between the average of the silicon wafer film thickness before and the target value determines the global etching time and the etching time interval, and the film thickness difference of each local area of the silicon wafer determines the action state (such as motion parameters, process parameters) and the heating state of the swing arm 300. Finally, the global average etching time, etching time interval and heating temperature required in the etching process can be automatically calculated and obtained, and precise control is not required for manual intervention.
[0067] At the same time, based on the wet etching equipment provided in each embodiment of the present application, a wet etching method is also provided, which includes steps S1 to S6 as described above.
[0068] The above wet etching method can be recorded, stored or fixed in one or more computer readable storage media, which includes program instructions executed by a computer to make the processor execute or implement the program instructions.
[0069] Therefore, when the wet etching equipment of the present application is used, not only can the dry heating of the silicon wafer 200 be realized through the heating clamp 100, but also the temperature compensation of the local area of the silicon wafer 200 in the etching process can be realized through the heating clamp 100. In this way, in the etching process, the silicon wafer partial circle etching time and the swing arm position can be adjusted according to the global etching time and the film thickness difference of the silicon wafer, and the temperature compensation can be performed according to the film thickness difference of the local area of the silicon wafer, which can etch more accurately and significantly improve the uniformity of wet etching.
[0070] It should be noted that in the above step S1, the etching area of the silicon wafer 200 adopts a concentric annular partitioning scheme, and the number of annular rings (n) is usually 3, but is not limited thereto, and the specific number can be set according to the etching condition of the photolithography machine.
[0071] As an example, the etching area of the silicon wafer 200 is divided into three concentric ring-shaped areas, namely, an inner ring 210, a middle ring 220, and an outer ring 230. Further, the swing arm 300 can be positioned to the inner ring 210, the middle ring 220, and the outer ring 230, respectively, to perform the operation of optimizing etching according to requirements, and the application does not require the order of positioning the swing arm 300 to the inner ring 210, the middle ring 220, and the outer ring 230.
[0072] In addition, for the ring-shaped etching area with a relatively thick film thickness, the swing speed of the swing arm 300 needs to be reduced, the residence time of the etchant 400 needs to be prolonged, and the etching depth needs to be increased; and for the ring-shaped etching area with a relatively thin film thickness, the swing speed of the swing arm 300 needs to be increased, the etchant 400 needs to be reduced, and over-etching needs to be avoided.
[0073] In some embodiments, the film thickness change can be monitored in real time and online, and the speed of the swing arm 300 can be dynamically adjusted, for example, the film thickness change can be monitored in real time by laser ranging, and the speed of the swing arm 300 can be automatically triggered for PID adjustment according to the film thickness change data.
[0074] It should be further noted that when the swing arm 300 directly sprays the etchant 400 to the target ring-shaped area, although the etching of the adjacent area will also be generated, the film thickness of the target ring-shaped area is relatively thick, the etchant is replaced quickly, and the etching speed is high, so that a deeper etching speed is achieved in the same time through a faster etching speed, and this selective etching can effectively improve the overall etching uniformity.
[0075] In some embodiments, the control device is used to adjust the position of the swing arm 300, control the etching time of the swing arm 300, and control the heating temperature of the heating clamp 100, in addition to determining the global average etching time, the etching time interval, and the heating temperature.
[0076] In some embodiments, the control device comprises:
[0077] a swing arm position control module for adjusting the position of the swing arm 300;
[0078] an etching time control module for controlling the etching time of the swing arm 300;
[0079] a temperature control module for controlling the heating temperature of the heating clamp 100; and
[0080] a calculation module for determining the global average etching time, the etching time interval, and the heating temperature.
[0081] The swing arm position control module can adjust the position of the swing arm 300 in response to external instructions, so that the swing arm 300 can move to the target ring-shaped area to perform the operation of optimizing etching, or move away from the target ring-shaped area to stop the operation of optimizing etching.
[0082] The etching time control module can control the swing arm 300 to match the etching time corresponding to the target annular region, and control the swing arm 300 to perform the operation of optimized etching according to the current set etching time; when the swing arm 300 reaches the etching time specified by the etching time, the etching is stopped.
[0083] The temperature control module can control the heating clamp 100 to match the heating temperature corresponding to each local area of the silicon wafer 200, and control the heating clamp 100 to heat the local area of the silicon wafer 200 according to the current set heating temperature; when the heating temperature is too high or too low, the temperature control module can also control the heating clamp 100 to adjust the heating temperature.
[0084] The calculation module performs the following operations:
[0085] Divide the etching area of the silicon wafer 200 into a plurality of concentric annular regions;
[0086] According to the film thickness distribution data of the silicon wafer 200, determine the film thickness average value of the silicon wafer 200, the film thickness difference of a plurality of annular regions, and the film thickness difference of the local area of the silicon wafer 200;
[0087] According to the target film thickness of the silicon wafer 200, the film thickness average value of the silicon wafer 200, and the preset etching rate, determine the global average etching time;
[0088] According to the film thickness difference of a plurality of annular regions and the global average etching time, determine the etching time of a plurality of annular regions;
[0089] According to the film thickness difference of the local area of the silicon wafer 200, determine the heating temperature of the local area of the silicon wafer 200.
[0090] In some embodiments, the calculation unit includes:
[0091] The film thickness difference analysis unit is configured to determine the film thickness average value of the silicon wafer 200, the film thickness difference of a plurality of annular regions, and the film thickness difference of the local area of the silicon wafer 200 according to the film thickness distribution data of the silicon wafer 200;
[0092] The region division unit is configured to divide the etching area of the silicon wafer 200 into a plurality of concentric annular regions;
[0093] The target value calculation unit is configured to calculate the global average etching time according to the target film thickness of the silicon wafer 200, the film thickness average value of the silicon wafer 200, and the preset etching rate;
[0094] The time matching unit is configured to determine the etching time of a plurality of annular regions according to the global average etching time and the film thickness difference of a plurality of annular regions;
[0095] A temperature compensation unit is configured to determine the heating temperature of the local area of the silicon wafer 200 according to the film thickness difference of the local area of the silicon wafer 200.
[0096] In this way, the control device is modularized, and the maintainability, development efficiency, risk control, performance and the like of the control device are improved.
[0097] The wet etching method provided in the embodiment is implemented based on the APC algorithm, and compared with the prior art, the improved APC algorithm can significantly improve etching precision and improve etching uniformity.
[0098] It should be understood that the division of the modules of the control device is only a logical division, and all or part of the modules can be integrated into one physical entity, or can be physically separated. The modules can all be implemented in the form of software called by a processing element, or all be implemented in the form of hardware, or part of the modules are implemented in the form of software called by a processing element, and part of the modules are implemented in the form of hardware. In addition, all or part of the modules can be integrated together, or can be independently implemented.
[0099] Reference Figure 1 In some embodiments, the heating fixture 100 comprises a heating base 101, a clamp 102 and a heating source 103; the heating base 101 is located below the silicon wafer 200 and can drive the silicon wafer 200 to rotate after being driven; the clamp 102 and the heating source 103 are both mounted on the heating base 101; the clamp 102 is used to clamp the edge of the silicon wafer 200; and the heating source 103 is located between the silicon wafer 200 and the heating base 101 and is used to heat each local area on the silicon wafer 200. It can be understood that the heating base 101 is connected with a driving source, and the heating fixture 100 drives the silicon wafer 200 to rotate together through the driving source. Since the driving mode is prior art, it will not be described.
[0100] In this way, the clamp 102 clamps the edge of the silicon wafer 200 without contacting the front surface and the back surface of the silicon wafer 200. The specific structure of the clamp 102 is not limited in the embodiment, and any known structure in the art can be used, for example, a hold pin, as long as the edge of the silicon wafer 200 can be clamped and fixed, and the silicon wafer 200 can rotate with the clamp 102.
[0101] In addition, the heating source 103 adopts a direct radiation heating mode. In a preferred embodiment, the heating source 103 comprises a plurality of LED light sources 104, the plurality of LED light sources 104 are arranged on the heating base 101 and are uniformly distributed, and form a plurality of independent heating zones, each heating zone is opposite to a local area on the silicon wafer 200. The LED light source 104 can provide accurate temperature control and better realize local area temperature compensation.
[0102] Since the heating area of a single LED light source 104 is small, in the preferred embodiment, a plurality of LED light sources 104 form a heating zone to heat a same local area on the silicon wafer 200. The following exemplary description is given.
[0103] As an example, the measured film thickness distribution data of the silicon wafer 200 is shown in Table 1. Figure 2 The film thickness distribution data of the silicon wafer 200 is shown in Table 1. Figure 2 In Table 1, the numbers 2300, 2305, 2309, 2310, 2311, 2313, 2314, 2315, 2316, 2317, 2318, 2319, 2320, 2321, 2322, 2323, 2324, 2325, 2326, 2327, 2330, 2331, 2332, 2333 represent the film thickness values of the local areas on the silicon wafer 200, and the unit is angstrom ( ), Figure 2 In Table 1, each grid represents a local area on the silicon wafer 200. The local area refers to a sub-area on the silicon wafer 200 divided by the grid, i.e., a small range part in the plurality of concentric annular areas. It should be noted that the division of the local area can be adjusted as needed, including but not limited to the cases described in the embodiments of the present application.
[0104] As an example, the film thickness values on the silicon wafer 200 are distributed in the form of a grid, and correspondingly, a plurality of LED light sources 104 are distributed in the form of a grid, and each grid forms a heating zone.
[0105] As an example, based on the film thickness distribution data of the silicon wafer 200 shown in Table 1, the heating temperature distribution of the silicon wafer 200 shown in Table 2 is determined. Figure 2 Figure 3 In Table 2, each grid represents a local area on the silicon wafer 200. Figure 3 In Table 2, the number at each grid represents the required heating temperature (unit: ℃) for compensation, i.e., each local area corresponds to a heating temperature for compensation, wherein the film thickness is the same, the heating temperature is the same, and the greater the film thickness value, the higher the heating temperature. Figure 3 In more detail, based on the film thickness distribution data of the silicon wafer 200 shown in Table 1, the heating temperature distribution of the silicon wafer 200 shown in Table 2 is determined.
[0106] Figure 4 For example, when the film thickness of each local area on the silicon wafer 200 is 2331, 2333, 2330, 2311, 2313, 2315, 2300, 2305, 2310, 2305, 2315, 2320, 2321, 2325 angstroms, respectively, the corresponding compensation heating temperature is 48.1℃, 48.3℃, 48℃, 46.1℃, 46.3℃, 46.5℃, 45℃, 45.5℃, 46℃, 45.5℃, 46℃, 47℃, 47.1℃, 47.5℃, respectively. Thus, during the etching process, all the heating zones work simultaneously to heat the corresponding local areas on the silicon wafer 200, thereby significantly improving the etching uniformity.
[0107] Notably, Figure 2 and Figure 3 The film thickness and heating temperature are illustrative and do not limit the present application.
[0108] It should be understood that the power and heating temperature of the LED light source 104 can be configured according to the film thickness difference of the local area of the silicon wafer 200, which is not limited in the present application.
[0109] The maximum heating temperature of the LED light source 104 is set in combination with the process parameters of the silicon wafer, and the minimum heating temperature is set based on the ambient temperature or the storage requirement of the silicon wafer 200. In a preferred embodiment, the heating temperature of the LED light source 104 is 23℃-100℃.
[0110] In a preferred embodiment, the LED light source 104 is 500-1500, which is uniformly distributed on the heating base 101.
[0111] The film thickness distribution data of the silicon wafer 200 can be measured automatically or manually. In a preferred embodiment, the wet etching equipment further comprises a film thickness measuring device for directly measuring the film thickness of the silicon wafer 200, obtaining the film thickness distribution data of the silicon wafer 200, and feeding back to the control device.
[0112] The rotation speed of the heating clamp 100 is adjusted according to the characteristics of the etchant 400. In a preferred embodiment, the rotation speed of the heating clamp 100 is 200rpm-1200rpm, and the specific value is determined by experimental test. Further, for high viscosity etchant, 800-1200rpm is used to promote the flow of the etchant; for low viscosity etchant, 200rpm-500rpm is used to prevent the etchant from splashing.
[0113] The present application does not limit the type of etchant 400, for example, including but not limited to DHF (dilute hydrofluoric acid), TMAH (tetramethylammonium hydroxide), NH4OH (ammonium hydroxide), SC1 (ammonium hydroxide, hydrogen peroxide, water mixture) and other wet etching agents 400.
[0114] Further, the working principle of the wet etching method provided in the embodiment is further described.
[0115] First step: calculate the global etching average time
[0116] Global etching average time = (target film thickness value - previous average film thickness value) / preset etching rate
[0117] In this way, the etching time that needs to be adjusted can be dynamically calculated according to the deviation of the current film thickness deposition state from the target;
[0118] Second step: match the etching time level
[0119] Analyze the film thickness difference according to the area (such as inner / middle / outer ring), and map the calculated global etching average time to the preset discrete time level;
[0120] As an example, as shown in the following table, N represents the global etching average time:
[0121] When the average film thickness of the outer ring, the middle ring or the inner ring is greater than the global average film thickness, the etching time is increased on the basis of the global etching average time, and a plurality of levels are formed, wherein the increased etching time is 5 seconds as a level, that is, +5s, +10s, +15s or +20s;
[0122] When the average film thickness of the outer ring, the middle ring or the inner ring is less than the global average film thickness, the etching time is reduced on the basis of the global etching average time, and a plurality of levels are formed, wherein the reduced etching time is 5 seconds as a level, that is, -5s, -10s, -15s or -20s;
[0123] When the average film thickness of the outer ring, the middle ring or the inner ring is equal to the global average film thickness, no adjustment is needed, and the global average etching time is directly used as the required etching time level. However, in general, the swing of the wet etching swing arm will cause certain non-uniformity, and the etching uniformity needs to be realized through continuous adjustment and temperature compensation.
[0124] It should be noted that the above reduced or increased etching time can be adjusted according to actual needs, including but not limited to 5 seconds as a level, and can also be less than 5 seconds or more than 5 seconds. In addition, the etching time level can also be changed, including but not limited to the 9 levels shown in the table.
[0125]
[0126] Third step: adjust the position of the swing arm
[0127] According to the etching time level selection corresponding swing arm movement mode (profile) is selected, and then combined with the film thickness difference of the area (inner / middle / outer ring), the swing arm position is adjusted accordingly;
[0128] Step 4: Temperature compensation optimization
[0129] According to the film thickness difference of the area (inner / middle / outer ring), the temperature distribution of the heating fixture is adjusted, the film thickness unevenness is eliminated through local temperature compensation, and local precise optimization is realized.
[0130] In summary, the wet etching equipment and the wet etching method provided by the present application realize high-precision etching and improve uniformity by optimizing etching time, adjusting swing arm position, and implementing temperature compensation (regional temperature control) on local areas of the silicon wafer.
[0131] The specific embodiments of the present application are described above. It should be understood that the present application is not limited to the above specific embodiments, and various changes or modifications can be made by those skilled in the art within the scope of the present application, which does not affect the essential content of the present application. In the case of no conflict, the embodiments of the present application and the features in the embodiments can be combined with each other arbitrarily.
Claims
1. A wet etching apparatus, characterized in that, include: Swing arm; Heating clamps; and control devices; The heating clamp is used to hold the edge of the silicon wafer, and when driven, it can cause the silicon wafer to rotate around its own central axis. The swing arm is positioned above the silicon wafer to spray etchant; The control device is configured to perform the following steps: The etched area of the silicon wafer is divided into multiple concentric ring-shaped regions; Based on the silicon wafer film thickness distribution data, the average silicon wafer film thickness, the film thickness differences in multiple annular regions, and the film thickness differences in local regions of the silicon wafer are determined. The global average etching time is determined based on the target film thickness of the silicon wafer, the average film thickness of the silicon wafer, and the preset etching rate. Based on the differences in film thickness in multiple annular regions and the global average etching time, multiple etching time levels for the annular regions are determined. The heating temperature of a local area of the silicon wafer is determined based on the difference in film thickness in a local area of the silicon wafer. Adjust the position of the swing arm and control the swing arm to spray etchant onto the target annular area according to the set etching time level, while simultaneously controlling the heating fixture to heat the local area of the silicon wafer according to the set heating temperature.
2. The wet etching apparatus according to claim 1, characterized in that, The control device includes: The swing arm position control module is used to adjust the position of the swing arm; An etching time control module is used to control the etching time of the swing arm; A temperature control module is used to control the heating temperature of the heating fixture; and, The calculation module is used to determine the global average etching time, the etching time level, and the heating temperature.
3. The wet etching apparatus according to claim 2, characterized in that, The computing unit includes: The film thickness difference analysis unit is used to determine the average film thickness of the silicon wafer, the film thickness difference of multiple annular regions, and the film thickness difference of local regions of the silicon wafer based on the silicon wafer film thickness distribution data. Region partitioning unit, used to divide the silicon wafer etching area into multiple concentric ring regions; The target value calculation unit is used to calculate the global average etching time based on the target film thickness of the silicon wafer, the average film thickness of the silicon wafer, and the preset etching rate. A time matching unit is used to determine multiple etching time levels for the annular regions based on the global average etching time and the thickness difference of the multiple annular regions. A temperature compensation unit is used to determine the heating temperature of a local area of the silicon wafer based on the film thickness difference in a local area of the silicon wafer.
4. The wet etching apparatus according to any one of claims 1-3, characterized in that, The heating fixture includes a heating base, a clamp, and a heating source; the heating base is located below the silicon wafer and can rotate the silicon wafer when driven; the clamp and the heating source are both mounted on the heating base; the clamp is used to hold the edge of the silicon wafer. The heating source is located between the silicon wafer and the heating base, and is used to heat a local area of the silicon wafer.
5. The wet etching apparatus according to claim 4, characterized in that, The heating source includes several LED light sources, which are evenly distributed on the heating base and form several independent heating zones. Each heating zone corresponds to a local area on the silicon wafer.
6. The wet etching apparatus according to claim 5, characterized in that, The LED light sources are arranged in a grid pattern, and each grid constitutes a heating zone.
7. The wet etching apparatus according to claim 5, characterized in that, The number of LED light sources is between 500 and 1500.
8. The wet etching apparatus according to claim 4, characterized in that, The heating temperature of the heating fixture is 23℃~100℃, and / or the rotation speed of the heating fixture is 200rpm~1200rpm.
9. A wet etching method, performed using the wet etching apparatus as described in any one of claims 1-8, characterized in that, The wet etching method includes: The etched area of the silicon wafer is divided into multiple concentric ring-shaped regions; Based on the silicon wafer film thickness distribution data, the average silicon wafer film thickness, the film thickness differences in multiple annular regions, and the film thickness differences in local regions of the silicon wafer are determined. The global average etching time is determined based on the target film thickness of the silicon wafer, the average film thickness of the silicon wafer, and the preset etching rate. Based on the differences in film thickness in multiple annular regions and the global average etching time, multiple etching time levels for the annular regions are determined. The heating temperature of a local area of the silicon wafer is determined based on the difference in film thickness in a local area of the silicon wafer. Adjust the position of the swing arm and control the swing arm to spray etchant onto the target annular area according to the set etching time level, while simultaneously controlling the heating fixture to heat the local area of the silicon wafer according to the set heating temperature.
10. The wet etching method according to claim 9, characterized in that, The step of determining the etching time settings for multiple annular regions includes: When the average film thickness of the annular region is greater than the global average film thickness, the etching time is increased based on the global average etching time, and this increased etching time is used as the etching time level required for the target annular region. When the average film thickness of the annular region is less than the global average film thickness, the etching time is reduced based on the global average etching time, and this reduction is used as the etching time level required for the target annular region. When the average film thickness of the annular region is equal to the global average film thickness, the global average etching time is used as the etching time level required for the target annular region.