Wet etching method and wet etching equipment

Abstract

The invention provides a wet etching method and wet etching equipment, the surface of a wafer is sequentially divided into a first etching area to an nth etching area which are concentrically distributed from the center to the edge, the first etching area is circular, and the second etching area to the nth etching area are annular; first to nth annular spraying regions corresponding to the first to nth etching regions are arranged; the ith annular spraying area covers the ith etching area of the wafer; n is an integer greater than or equal to 2, 1 < = i < = n, and i is an integer. The wet etching method comprises the following steps: acquiring a thickness value of each etching region on the surface of a wafer; calculating the thickness difference between the etching areas on the surface of the wafer; and regulating and controlling the spraying parameters of each annular spraying area according to the thickness difference between the etching areas. According to the technical scheme provided by the invention, the thickness difference from the center to the edge of the wafer is effectively controlled by spraying in different regions and dynamically regulating and controlling the etching rate of each region.

Description

Technical Field

[0001] The present application relates to the field of semiconductor etching technology, and in particular to a wet etching method and wet etching equipment. Background Art

[0002] Wet etching is a key process in semiconductor manufacturing, primarily used to remove materials (such as semiconductor films, metals, or dielectric layers) from the wafer surface to form the desired circuit pattern or structure. It achieves selective removal through a chemical reaction between a chemical etching solution and the material being etched.

[0003] Existing wet etching equipment mainly etches wafers by immersion or spraying, but there are some defects. For example, in the immersion etching process, due to the uneven flow distribution of the etching liquid in the reaction tank and temperature fluctuations, the etching rate varies across the wafer, which may in turn aggravate the thickness difference (TTV) between the center and edge of the wafer and reduce the etching yield. For another example, in the spray etching process, since the spray parameters of the shower head are generally preset parameters, the spray process may also aggravate the thickness difference between the center and edge of the wafer. In addition, for wafers with warpage, especially thin wafers with warpage, the thickness difference between the center and edge of the wafer is further aggravated due to stress release during the etching process. Summary of the Invention

[0004] The purpose of this application is to provide a wet etching method and wet etching equipment, which effectively controls the thickness difference from the center to the edge of the wafer by partitioned spraying and dynamically adjusting the etching rate of each partition.

[0005] In a first aspect, a wet etching method is provided, wherein a wafer surface is divided into concentrically distributed first to nth etching zones from the center to the edge, wherein the first etching zone is circular and the second to nth etching zones are annular; and first to nth annular spray zones are provided corresponding to the first to nth etching zones; the i-th annular spray zone covers the i-th etching zone of the wafer; n is an integer greater than or equal to 2, 1≤i≤n, and i is an integer;

[0006] Among them, the wet etching method includes:

[0007] S1. Obtain the thickness value of each etched area on the wafer surface;

[0008] S2. Calculate the thickness difference between the etched areas on the wafer surface;

[0009] S3. Regulating the spray parameters of each annular spray zone according to the thickness difference between each etching zone.

[0010] In one feasible solution, before step S1, the following steps are further included:

[0011] S0, set the total thickness deviation threshold TTV ex ;Total thickness deviation threshold TTV ex Refers to the qualified upper limit of the maximum thickness difference from the center to the edge of the wafer after etching;

[0012] After step S3, the method further includes:

[0013] S4. Obtain the thickness values ​​of several points on the wafer surface and calculate the total thickness deviation real-time value TTV t ;

[0014] S5. Determine the real-time value of total thickness deviation TTV t Total thickness deviation threshold TTV ex size;

[0015] If TTV t ≤TTV ex , then maintain the current spray parameters of each annular spray zone and repeat steps S4 and S5 until the etching process is completed or the spraying is ended;

[0016] If TTV t >TTV ex , then repeat steps S1 to S5.

[0017] In one feasible solution, step S1 includes:

[0018] Obtain the thickness values ​​of several points on the wafer surface and record the position information of each point;

[0019] According to the regional division of each etching area of ​​the wafer, the etching area to which each point belongs is determined;

[0020] The average value of the thickness values ​​of all points in each etching area is calculated as the thickness value of the current etching area.

[0021] In an practicable solution, the thicknesses of the etched regions of the wafer calculated in step S1 are T1, T2, ..., T n ;

[0022] Step S2 includes:

[0023] Set a reference thickness T m ;

[0024] The difference between the thickness of each etched area and the reference thickness is calculated in sequence, which are ΔT 1m =T1-T m , ΔT 2m =T2-T m ...ΔT nm =T n -T m ;

[0025] The spray parameters regulated in step S3 include at least the concentration of the etching solution; the step of regulating the concentration of the etching solution in each annular spray zone in step S3 includes:

[0026] Set the reference thickness T m The corresponding benchmark concentration is C0;

[0027] Establish a relationship between the thickness difference ΔT and the etching solution concentration adjustment amount ΔC, ΔC = k*ΔT; k is a proportional coefficient preset according to the etching process requirements;

[0028] Calculate the etching solution concentration of the i-th annular spray zone as C i =C0+Δc i =C0+k*ΔT im ;

[0029] Adjust the etching solution concentration of each annular spray zone to C i .

[0030] In a second aspect, the present application provides a wet etching apparatus comprising a carrier, a spray device, a thickness detection device, and a control device. The carrier is used to carry a wafer and drive the wafer to rotate. The spray area of ​​the spray device includes first to nth annular spray zones, centered at the center of the carrier and concentrically distributed from the center to the edge, where n is an integer greater than or equal to 2. The wafer surface is divided concentrically from the center to the edge into first to nth etching zones, the first etching zone being circular and the second to nth etching zones being annular. The i-th annular spray zone covers the i-th etching zone of the wafer; 1 ≤ i ≤ n, where i is an integer. A thickness detection device is disposed above the carrier and is used to detect and obtain the thickness of the n etching zones of the wafer. The control device is communicatively connected to at least the spray device and the thickness detection device. The control device determines the thickness difference between the n etching zones of the wafer using detection signals sent by the thickness detection device and adjusts the spray parameters of the n annular spray zones based on the thickness difference.

[0031] In an implementable solution, the spraying parameters include one or more of etching solution concentration, etching solution temperature, etching solution flow rate, and etching time.

[0032] In an practicable solution, the spraying device includes n spraying heads; the n spraying heads are respectively used to form n annular spraying areas.

[0033] In one feasible solution, the spray widths of the n spray heads are equal;

[0034] Alternatively, the spray head is configured to have an adjustable spray width and an adjustable radial position along the carrier.

[0035] In one feasible solution, the thickness detection device includes n thickness sensors, one thickness sensor is provided above each annular spray zone, and is used to measure the thickness of each etched area of ​​the wafer;

[0036] Alternatively, the thickness detection device includes at least one thickness sensor movably disposed above the carrier platform, and the movement direction of the thickness sensor is along the radial direction of the carrier platform.

[0037] In one feasible solution, the etching liquid temperature of the n annular spray zones decreases in sequence from the center to the edge;

[0038] Alternatively, at least the temperature of the etching liquid in the annular spraying area near the center is greater than the temperature of the etching liquid in the annular spraying area near the edge.

[0039] In an implementable solution, the concentration of the etching solution in the n annular spray zones decreases in sequence from the center to the edge.

[0040] Compared with the prior art, the beneficial effects of this application include at least:

[0041] The wet etching method and equipment of the present application divide the wafer surface into multiple etching zones, and each etching zone corresponds to a corresponding annular spray zone. Based on the thickness difference between the etching zones, the spray parameters of each annular spray zone are adjusted so that each etching zone has a specific etching rate, thereby increasing the etching rate of the etching zone with a larger wafer thickness, and then adjusting the thickness difference between the center and the edge of the wafer to adjust the thickness difference between the center and the edge of the wafer to the desired range as soon as possible.

[0042] Moreover, since the wet etching method and equipment of the present application can detect the thickness of each etching area and adjust the spray parameters of each annular spray area, even if the warped wafer causes the thickness difference from the center to the edge of the wafer to change due to stress release during the etching process, the wet etching method of the present application can determine the change in the thickness difference from the center to the edge of the wafer by obtaining the thickness values ​​of each etching area, and then can increase, decrease or maintain the etching rate of each etching area by adjusting the spray parameters of each annular spray area, thereby adjusting the thickness difference from the center to the edge of the warped wafer to the desired range as soon as possible. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following is a brief introduction to the drawings required for use in the embodiments. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without creative work.

[0044] Figure 1This is a simplified diagram of the process states in a wet etching method according to an embodiment of the present application.

[0045] Figure 2 This is a flow chart of a wet etching method shown in an embodiment of the present application.

[0046] Figure 3 This is a flow chart of another wet etching method shown in an embodiment of the present application.

[0047] Figure 4 This is a schematic diagram of the composition of a wet etching device shown in an embodiment of the present application.

[0048] Figure 5 This is a schematic diagram of the composition of another wet etching device shown in an embodiment of the present application.

[0049] In the figure: 1. Carrier; 2. Spraying device; 21. Spraying head; 23. Valve group module; 3. Thickness detection device; 31. Thickness sensor; 4. Control device; 5. Wafer. DETAILED DESCRIPTION

[0050] In order to make the purpose, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below in combination with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments.

[0051] Therefore, the following detailed description of the embodiments of the present application provided in the accompanying drawings is not intended to limit the scope of the present application for protection, but merely represents selected embodiments of the present application. All other embodiments obtained by persons of ordinary skill in the art based on the embodiments in the present application without creative work are within the scope of protection of the present application.

[0052] Example 1

[0053] An embodiment of the present application first provides a wet etching method, in which the surface of a wafer is divided into concentrically distributed first to nth etching zones from the center to the edge, the first etching zone is circular, and the second to nth etching zones are annular; and first to nth annular spray zones corresponding to the first to nth etching zones are set; the i-th annular spray zone covers the i-th etching zone of the wafer; n is an integer greater than or equal to 2, 1≤i≤n, and i is an integer.

[0054] For example, Figure 1As shown, the surface of wafer 5 is divided into three concentrically distributed etching zones from the center to the edge, denoted by K1, K2, and K3, respectively. The first etching zone is circular, and the second and third etching zones are annular. First, second, and third annular spray zones are provided corresponding to the first, second, and third etching zones, denoted by P1, P2, and P3, respectively.

[0055] like Figure 2 As shown, the wet etching method of this embodiment includes:

[0056] S1. Obtain the thickness value of each etched area on the wafer surface;

[0057] S2. Calculate the thickness difference between the etched areas on the wafer surface;

[0058] S3. Regulating the spray parameters of each annular spray zone according to the thickness difference between each etching zone.

[0059] It should be noted that steps S1 to S3 are generally configured to be executed cyclically, or can be configured to be executed cyclically at predetermined time intervals. For example, steps S1 to S3 are repeatedly executed cyclically until a predetermined cutoff condition is met. The cutoff condition may be, for example, the completion of the etching process, or the thickness difference from the center to the edge of the wafer reaching a desired range.

[0060] In this embodiment, in step S1, the thickness of the wafer can be detected by an ultrasonic sensor, infrared interferometer, or other device at a predetermined sampling frequency to determine the thickness of each etched area. This thickness value can be an average thickness value or a median thickness value. Furthermore, the thickness value of each etched area on the wafer surface is obtained at the predetermined sampling frequency.

[0061] In this embodiment, in step S2, the thickness difference between the etched areas on the wafer surface can be the thickness difference of each etched area relative to a set thickness value; or the thickness value of a certain etched area is used as a reference, and the thickness difference of other etched areas with this reference; or the thickness difference of adjacent etched areas is calculated in sequence.

[0062] In this embodiment, in step S3, the spray parameters of each annular spray zone are regulated, and the spray parameters include but are not limited to the etching solution concentration, etching solution temperature, etching solution flow rate, etching time, etc. The way to regulate the spray parameters of each annular spray zone includes but is not limited to regulating one or more of the spray parameters; or one or more spray parameters can be kept consistent, and one of the spray parameters can be regulated to change. By regulating the spray parameters of each etching zone, different etching zones have different etching rates, so that the overall thickness difference between the etching zones can be adjusted in real time or near real time. That is, by regulating the spray parameters of each etching zone, the etching rate of the etching zone with a relatively large thickness value is made greater than the etching rate of the etching zone with a relatively small thickness value, so that the overall thickness difference between the etching zones is adjusted to the desired level as soon as possible.

[0063] In summary, the wet etching method of this embodiment divides the wafer surface into multiple etching zones, and sets an annular spray zone corresponding to each etching zone. Based on the thickness difference between the etching zones, the spray parameters of each annular spray zone are adjusted so that each etching zone has a specific etching rate, thereby increasing the etching rate of the etching zone with a larger wafer thickness, and then adjusting the thickness difference between the center and the edge of the wafer to adjust the thickness difference between the center and the edge of the wafer to the desired range as soon as possible.

[0064] Moreover, since the wet etching method of this embodiment can detect the thickness of each etching area and adjust the spray parameters of each annular spray area, even if the stress of the warped wafer is released during the etching process, resulting in a change in the thickness difference from the center to the edge of the wafer, the wet etching method of the present application can determine the change in the thickness difference from the center to the edge of the wafer by obtaining the thickness values ​​of each etching area, and then can increase, decrease or maintain the etching rate of the etching area by adjusting the spray parameters of each annular spray area, thereby adjusting the thickness difference from the center to the edge of the warped wafer to the desired range as soon as possible.

[0065] In this embodiment, if Figure 3 As shown, the wet etching method may further include the following steps before step S1:

[0066] S0, set the total thickness deviation threshold TTV ex ;Total thickness deviation threshold TTV ex Refers to the qualified upper limit of the maximum thickness difference from the center to the edge of the wafer after etching; for example, TTV ex =0.3μm.

[0067] Furthermore, after step S3, the following steps may be further included:

[0068] S4. Obtain the thickness values ​​of several points on the wafer surface and calculate the total thickness deviation real-time value TTV t ;

[0069] S5. Determine the real-time value of total thickness deviation TTV t Total thickness deviation threshold TTV ex size;

[0070] If TTV t ≤TTV ex , then maintain the current spray parameters of each annular spray zone and repeat steps S4 and S5 until the etching process is completed or the spraying is ended;

[0071] If TTV t >TTV ex , then repeat steps S1 to S5.

[0072] For example, assuming that the TTV of a 300mm diameter wafer is reduced from 1.2μm in the traditional process to ≤0.3μm, its initial total thickness deviation (the thickness difference from the center to the edge of the wafer) is 1.2μm, and the total thickness deviation threshold TTV is ex =0.3μm. A 300mm diameter wafer can be divided into three etching zones and three annular spray zones can be set. Among them, the center of a 300mm diameter wafer is thicker and the edges are thinner.

[0073] First, the thickness values ​​of the three etched areas of the wafer are obtained at a predetermined sampling frequency (for example, 10 Hz), and then the thickness difference between each etched area is calculated. After that, the spray parameters of each annular spray area are adjusted. The etching liquid flow rate and etching liquid temperature can be kept consistent, and the etching liquid concentration can be adjusted. The etching liquid concentration can be set to increase by 5% for every 0.1 μm difference in thickness. For example, assuming that the thickness of the wafer in the center etching area is 0.1 μm thicker than that in the edge etching area, the etching liquid concentration in the annular spray area in the center is 5% higher than that in the annular spray area at the edge. After the aforementioned wet etching method, the TTV of a 300 mm diameter wafer can be reduced from 1.2 μm to about 0.25 μm, and 0.25 μm ≤ 0.3 μm. If the purpose is to reduce TTV, the spraying can be stopped at this time. If the etching purpose is to achieve other etching purposes (such as controlling wafer thickness) in addition to reducing TTV, the spray parameters of each annular spray zone are maintained, and then steps S4 and S5 are repeated until the etching process is completed.

[0074] In this embodiment, step S1 of the wet etching method may include:

[0075] S11, obtaining thickness values ​​of several points on the wafer surface and recording position information of each point;

[0076] S12, determining the etching area to which each point belongs according to the regional division of each etching area of ​​the wafer;

[0077] S13, calculating the average value of the thickness values ​​of all points in each etching area as the thickness value of the current etching area.

[0078] After obtaining the thickness values ​​of several points in step S11, a thickness distribution map of the wafer surface can be established. In step S12, the position of the point where the thickness value is obtained in the etched area can be determined based on the thickness distribution map and the division of the etched area.

[0079] In this embodiment, the thicknesses of the etched regions of the wafer calculated in step S1 of the wet etching method are T1, T2, ..., T n .

[0080] Then, step S2 may include:

[0081] S21. Set a reference thickness T m ;

[0082] S22, calculate the difference between the thickness of each etched area and the reference thickness in turn, which are ΔT 1m =T1-T m , ΔT 2m =T2-T m ...ΔT nm =T n -T m .

[0083] Among them, the reference thickness T m A separate value may be set, or the thickness value of a certain etched area before each adjustment may be selected as the reference thickness.

[0084] Furthermore, the spray parameters regulated in step S3 include at least the concentration of the etching solution. Then the step of regulating the concentration of the etching solution in each annular spray zone in step S3 may include:

[0085] S31. Set the reference thickness T m The corresponding reference concentration is C0; the reference concentration C0 can be determined according to actual process requirements;

[0086] S32, establishing a relationship between the thickness difference ΔT and the etching solution concentration adjustment amount ΔC, ΔC = k*ΔT; k is a proportional coefficient preset according to etching process requirements;

[0087] S33, calculate the etching solution concentration of the i-th annular spray zone as C i =C0+ΔC i =C0+k*ΔT im ;

[0088] S34, regulating the etching solution concentration of each annular spray zone to C i .

[0089] When adjusting the concentration of the etching solution, the consistency of other spray parameters may be maintained, or one or more other parameters may also be adjusted.

[0090] For example, for a wafer with a diameter greater than 400 mm, five etching zones can be divided, and five corresponding annular spray zones can be set. Set the base concentration to C0, and set C = k * ΔT = 0.5 * ΔT. The spray parameter adjustment during the method operation is shown in Table 1.

[0091] Table 1: Spray parameter adjustment table for a wafer

[0092]

[0093] This embodiment achieves accurate compensation of wafer etching thickness by introducing a zoned dynamic gradient control of etching solution concentration. im According to the proportional coefficient k (such as k = 0.5), the etching solution concentration of each annular spray zone is linearly adjusted to make the thicker area (such as ΔT im >0) concentration increases to accelerate etching, and thin areas (such as ΔT im <0) concentration reduction slows down etching. Combined with independent zone control (e.g., the five-zone differential adjustment in Table 1) and baseline concentration process compatibility, this significantly reduces wafer center-to-edge thickness variation. Furthermore, when adjusting etchant concentration parameters, maintaining consistency in other parameters (flow rate / pressure) avoids system perturbations, effectively reducing over- and under-etching defects.

[0094] In addition, for wafers of other sizes, such as 12-inch wafers with a radius of approximately 150mm, three etching zones can be divided into 50mm radius ranges, or other numbers of etching zones with different radius ranges can be divided. When dividing the etching zones, the thickness difference ΔT corresponding to adjacent etching zones should not be too large (it can be set according to actual conditions), and the difference in thickness between multiple adjacent etching zones should be kept close to a relatively uniform value. This also makes it easier to determine the relationship between the thickness difference ΔT and the etching solution concentration adjustment amount ΔC, facilitating subsequent control.

[0095] Example 2

[0096] This embodiment provides a wet etching device, which can at least implement the wet etching method of the first embodiment.

[0097] like Figure 4 and Figure 5 As shown, the wet etching equipment may include a carrier 1 , a spray device 2 , a thickness detection device 3 and a control device 4 .

[0098] Among them, the carrier 1 is used to carry the wafer and drive the wafer to rotate. The spray area of ​​the spray device 2 includes the first to nth annular spray areas (for example, P1 to P3 in the figure) with the center of the carrier 1 as the center and concentrically distributed from the center to the edge, where n is an integer greater than or equal to 2; the surface of the wafer is divided into the first to nth concentrically distributed etching areas (for example, K1 to K3 in the figure) from the center to the edge, the first etching area is circular, and the second to nth etching areas are annular; the i-th annular spray area covers the i-th etching area of ​​the wafer; 1≤i≤n, i is an integer. The thickness detection device 3 is arranged above the carrier 1, and is used to detect and obtain the thickness of the n etching areas of the wafer. The control device 4 is at least communicatively connected to the spray device 2 and the thickness detection device 3.

[0099] The control device 4 determines the thickness difference between the n etched areas of the wafer through the detection signal sent by the thickness detection device 3, and adjusts the spray parameters of the n annular spray areas according to the thickness difference.

[0100] When the wet etching equipment of this embodiment is in operation, it at least includes the following steps.

[0101] In the first step, the thickness value of each etched area on the wafer surface is obtained by the thickness detection device 3, and the position information of each point is recorded.

[0102] Specifically, the wafer 5 is placed on the carrier 1, and the carrier 1 drives the wafer 5 to rotate at a constant speed according to a predetermined angular velocity, and obtains the thickness values ​​of several points on the surface of the wafer 5 through the thickness detection device 3. The position information of the points on the wafer surface can be recorded by recording the rotation angle of the carrier 1, and these thickness values ​​and position information can be transmitted to the control device 4.

[0103] In the second step, the control device 4 calculates the thickness difference between the etched areas on the wafer surface.

[0104] Specifically, the control device 4 can establish a wafer thickness distribution map based on the etch zone division data of the wafer surface and the position information of each point on the wafer surface, or directly determine the etch zone to which each point belongs. Then, the average thickness value of all points in each etch zone can be calculated as the thickness value of the current etch zone, or the thickness value of each etch zone can be obtained by reselecting points from the established wafer thickness distribution map or by inferring the thickness distribution. After that, the thickness difference of each etch zone is calculated. The thickness difference between each etch zone on the wafer surface can be the thickness difference of each etch zone relative to a set thickness value; or the thickness difference of other etch zones relative to the thickness value of a certain etch zone can be calculated based on the thickness value of the etch zone; or the thickness difference of adjacent etch zones can be calculated in sequence.

[0105] In the third step, the control device 4 adjusts the spray parameters of each annular spray zone of the spray device 2 according to the thickness difference between the etching zones. The spray parameters include but are not limited to etching solution concentration, etching solution temperature, etching solution flow rate, etching time, etc.

[0106] In this embodiment, if Figure 4 As shown, the spray device 2 may include n spray heads 21, each of which is used to form n annular spray zones. Furthermore, the spray device 2 includes a valve group module 23, and the control device 4 adjusts the spray parameters of the spray heads 21 by controlling various valves preset in the valve group module 23.

[0107] In this embodiment, the spray widths of the n shower heads 21 may be set to be equal, and the widths of the corresponding etching areas on the surface of the wafer 5 are also preferably set to be equal.

[0108] In this embodiment, the spray head 21 can be configured to have an adjustable spray width, and as Figure 5 As shown, the showerhead 21 can be adjusted radially along the carrier 1. When the number and width of the etched areas on the surface of the wafer 5 are changed, the spray width of the showerhead 21 and the radial position of the showerhead 21 can be adjusted so that each showerhead 21 covers the corresponding etched area, thereby improving the flexibility and applicability of the method.

[0109] The spray head 21 may be driven to move radially by a linear displacement mechanism such as a synchronous belt module or a lead screw module.

[0110] In this embodiment, if Figure 4 As shown, the thickness detection device 3 may include n thickness sensors 31 , with one thickness sensor 31 disposed above each annular spraying area for measuring the thickness of each etched area of ​​the wafer 5 .

[0111] Alternatively, in this embodiment, Figure 5 As shown, the thickness detection device 3 may include at least one thickness sensor 31 movably arranged above the carrier 1. The moving direction of the thickness sensor 31 is along the radial direction of the carrier 1. The thickness values ​​of the wafer 5 at different diameters are obtained by moving the thickness sensor 31 radially.

[0112] The thickness measuring sensor 31 may be an ultrasonic sensor, an infrared interferometer, or the like.

[0113] In this embodiment, it can be configured that the etching liquid temperature of the n annular spray zones decreases in sequence from the center to the edge, thereby better coping with wafers that are thick in the center and thin at the edge.

[0114] In this embodiment, it can be configured that the etching liquid temperature of at least the annular spray area near the center is greater than the etching liquid temperature of the annular spray area near the edge, thereby reducing the impact of wafer stress release.

[0115] In this embodiment, it can be configured that the etching solution concentrations of the n annular spray zones decrease in sequence from the center to the edge.

[0116] It should be noted that in regulating the etching solution concentration, etching solution temperature, and etching solution flow rate, multiple parameters can be regulated, but it is preferred to adjust only the same parameter within the same adjustment time interval and maintain the consistency of other parameters within this adjustment time interval.

[0117] When the wet etching equipment of this embodiment performs etching, before obtaining the thickness value of each etched area on the wafer surface through the thickness detection device 3 and recording the position information of each point, it can also include setting the total thickness deviation threshold TTV in the control device 4 ex ;Total thickness deviation threshold TTV ex It refers to the qualified upper limit of the maximum thickness difference from the center to the edge of the wafer after etching.

[0118] After the control device 4 adjusts the spray parameters of each annular spray area of ​​the spray device 2 according to the thickness difference between each etched area, the following steps may also be included:

[0119] Step 4: The thickness detection device 3 is used to obtain the thickness values ​​of several points on the wafer surface, and the control device 4 calculates the total thickness deviation real-time value TTV. t ;

[0120] Step 5: The control device 4 determines the total thickness deviation real-time value TTV t Total thickness deviation threshold TTV ex size;

[0121] If TTV t ≤TTV ex , the control device 4 controls each shower head 21 to maintain the current shower parameters, and repeats the fourth and fifth steps until the etching process is completed or the shower is finished;

[0122] If TTV t >TTV ex , then repeat steps 1 to 5.

[0123] In this embodiment, the thickness of each etched area of ​​the wafer calculated in the first step can be recorded as T1, T2...T n .

[0124] Then, in the second step, the step of calculating the thickness difference between the etched areas on the wafer surface by the control device 4 may include:

[0125] The control device 4 sets a reference thickness T m ;

[0126] The control device 4 sequentially calculates the difference between the thickness of each etched area and the reference thickness, which are ΔT 1m =T1-T m , ΔT 2m =T2-T m ...ΔT nm =T n -T m .

[0127] Among them, the reference thickness T m A separate value may be set, or the thickness value of a certain etched area before each adjustment may be selected as the reference thickness.

[0128] Furthermore, in the third step, the control device 4 regulates the spray parameters of each annular spray zone of the spray device 2 according to the thickness difference between the etching zones, wherein the regulated spray parameters include at least the etching solution concentration. The step of regulating the etching solution concentration of each annular spray zone in the third step may include:

[0129] The control device 4 sets the reference thickness T m The corresponding reference concentration is C0; the reference concentration C0 can be determined according to actual process requirements;

[0130] The control device 4 establishes a relationship between the thickness difference ΔT and the etching solution concentration adjustment amount ΔC, ΔC = k*ΔT; k is a proportional coefficient preset according to the etching process requirements;

[0131] The control device 4 calculates the etching solution concentration of the i-th annular spray zone as C i =C0+ΔC i =C0+k*ΔT im ;

[0132] The control device 4 controls the valve group module 23 to operate, thereby adjusting the concentration of the etching solution sprayed by each spray head 21 to C i , that is, to achieve the control of the etching solution concentration of each annular spray zone to C i .

[0133] In summary, the wet etching equipment of this embodiment can at least realize the wet etching method of embodiment one, and it sets up nested annular spray areas through the spray device 2, and divides the wafer into etching areas corresponding to the annular spray areas one by one, and can determine the thickness difference between each etching area through the parameters obtained by the thickness detection device 3, and then adjust the spray parameters of each annular spray area of ​​the spray device 2 so that each etching area has a specific etching rate, thereby increasing the etching rate of the etching area with a larger wafer thickness, and then adjusting the thickness difference between the center and the edge of the wafer to adjust the thickness difference between the center and the edge of the wafer to within the desired range as soon as possible.

[0134] The foregoing description is merely a partial list of preferred embodiments of the present application and is not intended to limit the present application. Persons skilled in the art will readily appreciate that various modifications and variations are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present application shall be included within the scope of protection of the present application.

Claims

1. A wet etching method, characterized in that: The wafer surface is divided into concentrically distributed first to nth etching zones from the center to the edge, wherein the first etching zone is circular and the second to nth etching zones are annular; and first to nth annular spray zones are provided corresponding to the first to nth etching zones; the i-th annular spray zone covers the i-th etching zone of the wafer; n is an integer greater than or equal to 2, 1≤i≤n, i is an integer; The wet etching method comprises: S1. Obtain the thickness value of each etched area on the wafer surface; S2. Calculate the thickness difference between the etched areas on the wafer surface; S3. Regulating the spray parameters of each annular spray zone according to the thickness difference between each etching zone.

2. The wet etching method according to claim 1, wherein: Before step S1, the method further includes: S0, set the total thickness deviation threshold TTV ex ; The total thickness deviation threshold TTV ex Refers to the qualified upper limit of the maximum thickness difference from the center to the edge of the wafer after etching; After step S3, the method further includes: S4. Obtain the thickness values ​​of several points on the wafer surface and calculate the total thickness deviation real-time value TTV t ; S5. Determine the real-time value of total thickness deviation TTV t Total thickness deviation threshold TTV ex size; If TTV t ≤TTV ex , then maintain the current spray parameters of each annular spray zone and repeat steps S4 and S5 until the etching process is completed or the spraying is ended; If TTV t >TTV ex , then repeat steps S1 to S5.

3. The wet etching method according to claim 1, wherein: The step S1 comprises: Obtain the thickness values ​​of several points on the wafer surface and record the position information of each point; According to the regional division of each etching area of ​​the wafer, the etching area to which each point belongs is determined; The average value of the thickness values ​​of all points in each etching area is calculated as the thickness value of the current etching area.

4. The wet etching method according to claim 1, wherein: The thicknesses of the etched areas of the wafer calculated in step S1 are T1, T2, ..., T n ; The step S2 comprises: Set a reference thickness T m ; The difference between the thickness of each etched area and the reference thickness is calculated in sequence, which are ΔT 1m =T1-T m , ΔT 2m =T2-T m ...ΔT nm =T n -T m ; The spray parameters regulated in step S3 include at least the concentration of the etching solution; the step of regulating the concentration of the etching solution in each annular spray zone in step S3 includes: Set the reference thickness T m The corresponding benchmark concentration is C0; Establish a relationship between the thickness difference ΔT and the etching solution concentration adjustment amount ΔC, ΔC = k*ΔT; k is a proportional coefficient preset according to the etching process requirements; Calculate the etching solution concentration of the i-th annular spray zone as C i =C0+ΔC i =C0+k*ΔT im ; Adjust the etching solution concentration of each annular spray zone to C i .

5. A wet etching device, characterized in that: include: A carrier platform (1) for carrying wafers and driving the wafers to rotate; A spraying device (2), wherein the spraying area includes first to nth annular spraying areas which are concentrically distributed from the center of the carrier (1) to the edge, wherein n is an integer greater than or equal to 2; the surface of the wafer is divided into first to nth etched areas which are concentrically distributed from the center to the edge, wherein the first etched area is circular and the second to nth etched areas are annular; the i-th annular spraying area covers the i-th etched area of ​​the wafer; 1≤i≤n, wherein i is an integer; A thickness detection device (3), arranged above the carrier platform (1), is used to detect and obtain the thickness of n etched areas of the wafer; a control device (4) in communication connection with at least the spraying device (2) and the thickness detection device (3); The control device (4) determines the thickness difference between the n etched areas of the wafer through the detection signal sent by the thickness detection device (3), and adjusts the spray parameters of the n annular spray areas according to the thickness difference.

6. The wet etching equipment according to claim 5, characterized in that: The spraying parameters include one or more of etching solution concentration, etching solution temperature, etching solution flow rate, and etching time.

7. The wet etching equipment according to claim 5, characterized in that: The spraying device (2) comprises n spraying heads (21); The n spray heads (21) are respectively used to form n annular spray areas.

8. The wet etching equipment according to claim 7, characterized in that: The spray widths of the n spray heads (21) are equal; Alternatively, the spray head (21) is configured to have an adjustable spray width and an adjustable radial position along the carrier platform (1).

9. The wet etching equipment according to claim 5, characterized in that: The thickness detection device (3) comprises n thickness measuring sensors, one of which is arranged above each of the annular spraying areas, and is used to measure the thickness of each of the etched areas of the wafer; Alternatively, the thickness detection device (3) comprises at least one thickness sensor movably arranged above the carrier platform (1), and the movement direction of the thickness sensor is along the radial direction of the carrier platform (1).

10. The wet etching equipment according to claim 5, characterized in that: From the center to the edge, the temperature of the etching liquid in the n annular spray zones decreases in sequence; Alternatively, at least the temperature of the etching liquid in the annular spraying area near the center is greater than the temperature of the etching liquid in the annular spraying area near the edge.

11. The wet etching equipment according to claim 5, characterized in that: From the center to the edge, the etching solution concentrations of the n annular spray zones decrease in sequence.

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