Method for removing photoresist on wafer and semiconductor process equipment

Abstract

The invention provides a method for removing photoresist on a wafer and semiconductor process equipment, and the method comprises the steps: obtaining the corresponding spectral intensities of emitted light generated by a specific element in a cavity at different sampling moments in the process of removing the photoresist after ion implantation; according to the spectral intensities corresponding to the two adjacent sampling moments, determining the change characteristic quantity of the spectral intensity at each sampling moment; and when the change characteristic quantity corresponding to the current sampling moment meets a preset condition, determining that the hardened layer removal process is close to an end point and controlling the wafer to descend from the current position to the direction of the heating base according to a preset relation so as to remove the hardened layer of the photoresist. The spectral intensity of the emitted light generated by the specific element is acquired, whether the hardened layer removal process is close to the end point or not is judged according to whether the change characteristic quantity of the spectral intensity meets the preset condition or not, and the wafer is controlled to descend for heating when the hardened layer removal process is close to the end point, so that the hardened layer is prevented from bursting at high temperature.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor manufacturing, and in particular to a method for removing photoresist on a wafer and semiconductor process equipment. Background Art

[0002] In the semiconductor process, it is necessary to process extremely fine-sized patterns on the wafer. Usually, photolithography technology is used to transfer the circuit pattern on the mask to the photoresist covering the surface of the wafer, and then etching technology is used to transfer the photoresist pattern to the wafer. In order to prevent the wafer from being affected by the photoresist in the subsequent process, it is necessary to remove the residual photoresist on the wafer. In the ordinary dry stripping process technology, the wafer is generally directly placed at a high temperature for stripping, but ion implantation of photoresist will carbonize the surface of the photoresist, so that the photoresist forms a hardened layer 110 (such as Figure 1 As shown in FIG. 1 , the hardened layer 110 is coated on the outside of the uncrosslinked layer 120 and is prone to popping at high temperatures. Summary of the invention

[0003] The present invention aims to solve at least one of the technical problems existing in the prior art, and proposes a method for removing photoresist on a wafer and a semiconductor process equipment.

[0004] To achieve the purpose of the present invention, a method for removing photoresist on a wafer is provided, comprising:

[0005] In the process of removing the photoresist after ion implantation, the spectral intensity of the emission light generated by a specific element in the chamber corresponding to different sampling times is obtained;

[0006] Determining a change characteristic amount of the spectral intensity at each of the sampling moments according to the spectral intensities corresponding to two adjacent sampling moments;

[0007] When the change characteristic quantity corresponding to the current sampling moment meets the preset conditions, it is determined that the hardened layer removal process is close to the end point and the wafer is controlled to descend from the current position toward the heating base according to a preset relationship to remove the hardened layer of the photoresist.

[0008] In the removal method as described above, the change characteristic quantity is the rate of decrease of the spectral intensity between two adjacent sampling moments, and the change characteristic quantity satisfies the following relationship:

[0009] Q n =[S(t n-1 )-S(t n )]÷S(t n-1 ), where Q nis the change characteristic quantity corresponding to the nth sampling moment, S(t n ) is the spectral intensity corresponding to the nth sampling moment, and n is a positive integer.

[0010] In the removal method as described above, the preset condition includes that the change characteristic quantity corresponding to the current sampling moment is greater than a preset value, and the preset value is a non-negative number.

[0011] In the removal method as described above, the preset value is greater than or equal to 5% and less than or equal to 20%.

[0012] In the removal method as described above, the preset condition further includes a delay time between the moment when the spectral intensity reaches a maximum value and the current sampling moment.

[0013] The removal method as described above, wherein the delay duration is calculated according to the following relationship:

[0014] T=k / Q max ; Wherein, T is the delay time; k>0, and k is a constant; Q max It is the maximum value of the absolute value of the change characteristic quantity before the spectral intensity reaches the maximum value.

[0015] In the removal method as described above, the preset relationship is that the falling displacement Δh of the wafer is equal to the product of the falling time Δt and a constant a, and a is greater than 0.

[0016] The removal method as described above, wherein, before obtaining the spectral intensity corresponding to the emission light generated by the specific element in the chamber at different sampling times, the removal method further comprises:

[0017] The wafer is placed on the carrying surface of the heating base, and after the preheating time is reached, the wafer is controlled to rise to an initial high position.

[0018] The removal method as described above, wherein, after controlling the wafer to descend from the current position toward the heating base according to a preset relationship to remove the hardened layer of the photoresist, further comprises:

[0019] When the change characteristic quantity corresponding to the current sampling moment meets the termination condition for removing the hardened layer, the wafer is controlled to descend to the carrying surface of the heating base to remove the uncross-linked layer of the photoresist.

[0020] As another technical solution, the present invention also provides a semiconductor process equipment, comprising: a chamber, a heating base and a controller, wherein the heating base is arranged in the chamber and has a carrying surface for carrying a wafer; the controller comprises at least one processor and at least one memory, wherein the memory stores a computer program, and the processor executes the computer program to execute any one of the removal methods described in the present invention.

[0021] The present invention has the following beneficial effects:

[0022] The method for removing photoresist on a wafer and the semiconductor process equipment provided by the present invention obtain the spectral intensity of the emitted light generated by a specific element, and judge whether the hardening layer removal process is close to the end point according to whether the characteristic quantity of the change in the spectral intensity meets the preset conditions. When the hardening layer removal process is close to the end point, the wafer is controlled to descend and the temperature is increased to avoid the hardening layer from bursting at high temperature.

[0023] Moreover, by applying the removal method of the present invention, the wafer is lowered before the hardened layer removal process reaches the end point. In this way, under the premise of ensuring that the hardened layer will not burst, on the one hand, the rate of removing the residual hardened layer is increased, so that the small amount of residual hardened layer is quickly removed during the wafer lowering process, and the hardened layer removal process can reach the end point in advance, shortening the time for removing the hardened layer, thereby improving the degumming efficiency. On the other hand, before the hardened layer removal process reaches the end point, the distance between the wafer and the carrying surface is gradually reduced, and the temperature of the wafer is increased, so as to shorten as much as possible the time required for the temperature of the wafer to rise to remove the uncrosslinked layer when the hardened layer removal process reaches the end point, thereby improving the degumming efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 is a schematic diagram of the photoresist after ion implantation;

[0025] Figure 2 is a schematic diagram of the relationship between the temperature of the wafer and the distance between the wafer and the carrying surface;

[0026] Figure 3 A schematic diagram of the structure of a semiconductor process equipment provided in an embodiment of the present application;

[0027] Figure 4 A schematic diagram of a hardware module of a semiconductor process equipment provided in an embodiment of the present application;

[0028] Figure 5 A schematic diagram of a process for removing photoresist on a wafer provided in an embodiment of the present application;

[0029] Figure 6 It is a schematic diagram of the relationship between the temperature of the wafer and the degumming rate;

[0030] Figure 7It is a curve relationship diagram of the spectrum intensity and the sampling time in the process of the debonding process for controlling the wafer to descend when the hardening layer removal process reaches the end point;

[0031] Figure 8 for Figure 7 A curve relationship diagram of the height of the wafer relative to the carrier surface and the sampling time during the corresponding debonding process;

[0032] Fig. 9 A curve relationship diagram of spectral intensity and sampling time during a degumming process using a removal method provided in an embodiment of the present application;

[0033] Fig.10 for Fig. 9 A curve relationship diagram of the height of the wafer relative to the carrier surface and the sampling time during the corresponding debonding process;

[0034] Fig.11 A curve relationship diagram of spectral intensity and sampling time during a degumming process using another degumming method provided by an embodiment of the present application;

[0035] Fig.12 for Fig.11 A curve relationship diagram of the height of the wafer relative to the carrier surface and the sampling time during the corresponding debonding process;

[0036] Fig.13 A schematic flow chart of another method for removing photoresist on a wafer provided in an embodiment of the present application. DETAILED DESCRIPTION

[0037] Before introducing the embodiments of the present application, the related technology is first described.

[0038] Since the hardened layer 110 will burst at high temperatures, in order to avoid the popping phenomenon, the following steps can be used for the debonding process after ion implantation. Step 1: Hardened layer 110 removal process step, adjust the temperature of the wafer to a lower temperature value, and inject O2 and a mixed gas of N2 and H2. O2 can remove elements such as C, H, N, and S in the hardened layer 110. The mixed gas of N2 and H2 can make non-volatile substances (oxides such as P2O5 and As2O3) react with H to form volatile products. Step 2: Uncrosslinked layer 120 removal process step, adjust the temperature of the wafer to a higher temperature value, and inject O2. O2 reacts with the uncrosslinked layer 120 to form volatile products.

[0039] When using semiconductor process equipment to debond the wafer, the wafer can be placed on the carrying surface of the heating base. At this time, the heating base carries the wafer, and the wafer can also be moved relative to the heating base to a certain distance from the carrying surface. Among them, a heater is provided on the heating base. The heater is powered on to heat the heating base to drive the heating base to heat up. The heat of the heating base is transferred to the wafer to adjust the temperature of the wafer. The temperature of the wafer is related to the distance between the wafer and the carrying surface. The relationship between the two can be referred to Figure 2 Specifically, along the vertical direction, the smaller the distance between the wafer and the carrying surface, the higher the temperature of the wafer; along the vertical direction, the larger the distance between the wafer and the carrying surface, the lower the temperature of the wafer.

[0040] Based on this, it is necessary to reasonably adjust the distance between the wafer and the carrying surface to control the semiconductor process equipment to first perform the hardened layer removal process step, and then perform the uncross-linked layer removal process step after the hardened layer is removed.

[0041] In the related art, the distance between the wafer and the carrier surface and the process time in the hardened layer removal process step are set as empirical values, and the distance between the wafer and the carrier surface and the process time in the uncrosslinked layer removal process step are set as empirical values, thereby forming a specific process recipe. When the same process recipe is used for debonding, the lifting process of the wafer is the same.

[0042] However, the inventor of the present application has found that due to the different ion implantation amounts of different types of wafers, the thickness of the hardened layer of different types of wafers is different. Therefore, when using a specific process formula to remove the glue of different types of wafers, the following problems are prone to occur. First, before the process duration of the hardened layer removal process step reaches the set empirical value, the hardened layer has been removed cleanly, and the distance between the wafer and the bearing surface is still large, and it is not switched from step 1 to step 2 in time, resulting in a long time-consuming degumming process, low efficiency, and low production capacity. Second, when the process duration of the hardened layer removal process step reaches the set empirical value, the hardened layer has not been removed cleanly, and the distance between the wafer and the bearing surface is reduced. It is switched from step 1 to step 2 too early, causing the hardened layer to burst at a higher temperature. It can be seen that the use of a specific process formula for degumming cannot be adapted to different types of wafers.

[0043] The essence of these problems is that because the thickness of the hardened layer of different types of wafers is different, a specific process formula is used for degumming. When the process time of the hardened layer removal process step reaches the set empirical value, the end point of the hardened layer removal process is reached by default, which can easily cause the end point of the hardened layer removal process.

[0044] In order to solve the above-mentioned problems existing in the related art, the inventor of the present application has proposed a method for removing photoresist on a wafer, and judges whether the hardened layer removal process has reached an end point according to the spectral intensity of the emitted light generated by a specific element in a chamber. When the hardened layer removal process reaches an end point, the wafer is controlled to descend onto a heating base so that the wafer is heated up to remove the uncrosslinked layer. In this way, the end point of the hardened layer removal process is determined according to the signal change of the spectral intensity, and the automatic detection of the end point of the hardened layer removal process is realized. In addition, during the hardened layer removal process, the spectral intensity of the specific element changes with the change of the amount of the process gas or the reaction gas containing the specific element. Therefore, even if the thickness of the hardened layer of the photoresist formed by the wafer manufactured by the same process is different, the progress of the photoresist removal process can be accurately monitored by using this method, and the accuracy of determining the end point of the hardened layer removal process is high.

[0045] However, in actual application, the wafer is heated up due to the thermal radiation from the heating base, and the wafer heating process requires a certain amount of time. Therefore, the wafer is controlled to descend only when the hardened layer removal process reaches the end point. The wafer cannot be quickly heated up to the higher temperature value required to remove the uncross-linked layer, resulting in low removal efficiency of the hardened layer and the uncross-linked layer.

[0046] In order to improve the de-gumming efficiency, the embodiments of the present application further provide a method for removing photoresist on a wafer and a semiconductor process equipment.

[0047] Figure 3 This is a schematic diagram of the structure of a semiconductor process equipment provided by an embodiment of the present application. Figure 3 The semiconductor process equipment includes a chamber 200 and a heating base 400, wherein the heating base 400 is located in the chamber 200 and has a carrying surface for carrying a wafer 300. The chamber 200 can implement a stripping process to remove ordinary photoresist or photoresist after ion implantation on the surface of the wafer 300.

[0048] A heater 410 is disposed inside the heating base 400 . The heater 410 is connected to a power source 500 disposed outside the chamber 200 . The heater 410 is powered on for heating, so that the heating base 400 is heated.

[0049] In some embodiments, the semiconductor process equipment further includes a lifting assembly (not shown in the figure) and three lifting pins 210. The heating base 400 is provided with three through holes corresponding to the three lifting pins 210. The three lifting pins 210 abut against the back of the wafer 300. The lifting assembly is used to drive the three lifting pins 210 to rise and fall along the corresponding through holes, so that the distance between the wafer 300 and the bearing surface of the heating base 400 changes, so as to change the heat radiated from the heating base 400 to the wafer 300, thereby adjusting the temperature of the wafer 300. It is understandable that the number of lifting pins 210 is not limited to three, and can be specifically designed based on experience and actual working conditions.

[0050] Figure 4 A schematic diagram of a hardware module of a semiconductor process equipment provided in an embodiment of the present application. Please refer to Figure 3 and Figure 4 The semiconductor process equipment further includes a spectrum intensity detection device 800 and a controller 700 .

[0051] Exemplarily, the controller 700 includes at least one processor 710 and at least one memory 720. The memory 720 may be used to store program code. The memory 720 may be configured as any type of memory 720. For example, the memory 720 may be implemented as a flash memory (flash), a read-only memory (ROM), a random access memory (RAM), a removable memory, other types of storage elements, or any combination of such storage devices.

[0052] The processor 710 can be used to execute the above application code and call related modules to implement the functions of the semiconductor process equipment in the embodiment of the present application. The processor 710 may include one or more processing units, for example: the processor 710 may include an application processor (application processor, AP), a modem processor, a graphics processor (graphics processing unit, GPU), an image signal processor (image signal processor, ISP), a video codec, a digital signal processor (digital signal processor, DSP), a baseband processor, and / or a neural-network processing unit (neural-network processing unit, NPU), etc. Among them, different processing units can be independent devices or integrated in one or more processors 710.

[0053] The spectrum intensity detection device 800 is used to detect the spectrum intensity of the emitted light generated by a specific element. The spectrum intensity detection device 800 is electrically connected to the controller 700 to send the detected spectrum intensity to the controller 700. The spectrum intensity detection device 800 can be implemented by a spectrum sensor. The spectrum intensity detection device 800 can detect the spectrum intensity in real time or collect the spectrum intensity at each preset time interval.

[0054] In some embodiments, the semiconductor process equipment disclosed herein may further include a first timer 910 and a second timer 920 , both of which are connected to the controller 700 , and both of which are used for timing.

[0055] The controller 700 is also connected to the lifting assembly via a communication module 930 to control the lifting assembly. The communication module 930 may be implemented as one or more any conventional communication interfaces.

[0056] It is understood that the structure illustrated in the embodiment of the present invention does not constitute a specific limitation on the semiconductor process equipment. In other embodiments of the present invention, the semiconductor process equipment may include more or fewer components than shown in the figure, or combine some components, or split some components, or arrange the components differently. The components shown in the figure may be implemented in hardware, software, or a combination of software and hardware.

[0057] Figure 5 A schematic diagram of a process flow of a method for removing photoresist from a wafer provided in an embodiment of the present application. For the above-mentioned semiconductor process equipment, a method for removing photoresist from a wafer can be executed. The specific process of the removal method can be found in Figure 5 ,include:

[0058] S101, in the process of removing the photoresist after ion implantation, obtaining the spectral intensity corresponding to the emission light generated by a specific element in the chamber at different sampling times.

[0059] The specific element may refer to an element implanted by ions, such as P, As, B, etc.

[0060] This step can specifically be achieved by receiving the spectrum intensity detected by the spectrum intensity detection device 800, thereby acquiring the spectrum intensity.

[0061] There is a one-to-one correspondence between each sampling moment and the spectral intensity at that sampling moment. Similarly, the time from each sampling moment to the first sampling moment is the sampling duration, and there is also a one-to-one correspondence between the sampling duration and the spectral intensity corresponding to the sampling duration.

[0062] S102, determining a change characteristic amount of the spectrum intensity at each sampling moment according to the spectrum intensity corresponding to two adjacent sampling moments.

[0063] S103, when the change characteristic quantity corresponding to the current sampling moment meets the preset conditions, it is determined that the hardened layer removal process is close to the end point and the wafer is controlled to descend from the current position toward the heating base according to the preset relationship to remove the hardened layer of the photoresist.

[0064] It should be pointed out that the preset conditions should be reasonably designed so that the change characteristic quantity corresponding to the current sampling moment should meet the preset conditions before meeting the hardened layer removal termination conditions. The change characteristic quantity corresponding to the current sampling moment meeting the preset conditions should be able to indicate that most of the hardened layer has been removed, the hardened layer has not been completely removed, a small amount of hardened layer remains, and the hardened layer removal process is close to the end.

[0065] The characteristic quantity of the change in spectral intensity should be able to reflect the progress of the debonding process, so that it can be accurately judged that the hardened layer removal process step is close to the end point based on the characteristic quantity of the change. Therefore, the specific element must also meet the characteristics that the change trend of the spectral intensity corresponding to the process of removing the hardened layer is different from the change trend of the spectral intensity corresponding to the process of removing the uncrosslinked layer.

[0066] Combined with the above description, it can be seen that when the process of removing the hardened layer begins, the wafer should be at the initial high position. At this time, the distance between the wafer and the carrying surface is H1, so that the temperature of the wafer is lower than or equal to 200°C to avoid popping. The general process of the removal method of this embodiment is as follows: if the change characteristic quantity corresponding to the current sampling moment meets the preset conditions, the wafer is controlled to descend from the initial high position to approach the heating base, so that the wafer is heated up, and the small amount of residual hardened layer is cleared at the same time; during the descent process, the spectral intensity of the emission light generated by the specific element is continued to be obtained. If the change characteristic quantity corresponding to the current sampling moment still meets the preset conditions, the wafer is controlled to descend from the current position, and the small amount of residual hardened layer is continued to be cleaned until the hardened layer is completely cleared.

[0067] As disclosed in the removal method, controlling the wafer to descend from the current position toward the heating base can be achieved in the following manner: For example, by sending a signal to the lifting component, the lifting component drives the lifting needle to descend, thereby driving the wafer to descend.

[0068] The removal method of this embodiment obtains the spectral intensity of the emitted light generated by a specific element, and determines whether the hardening layer removal process is close to the end point according to whether the characteristic quantity of the change in the spectral intensity meets the preset conditions. When the hardening layer removal process is close to the end point, the wafer is controlled to descend and the temperature is increased. In other words, before the wafer descends, the distance between the wafer and the heating base is large, and the temperature of the wafer is relatively low to avoid the hardening layer from bursting at high temperatures. It is worth pointing out that since only a small amount of hardening layer remains that has not been cleaned up when the hardening layer removal process is close to the end point, at this time, even if the wafer descends and the temperature is increased, the remaining small amount of hardening layer will not burst. Therefore, the removal method of this embodiment can effectively solve the problem of the hardening layer bursting at high temperatures.

[0069] It can be understood that during the degumming process, when the wafer temperature is the only variable in the process conditions, the degumming rate is positively correlated with the wafer temperature. For details, please refer to Figure 6 As shown, the higher the wafer temperature, the faster the degumming rate. Based on this, in the removal method of this embodiment, the wafer drops before the hardened layer removal process reaches the end point. In this way, when degumming using the removal method of this embodiment, since part of the hardened layer has been removed, its thickness becomes thinner. By controlling the wafer to drop according to a preset relationship, "popping" can be avoided. On the one hand, the temperature of the wafer can be increased, so that the remaining hardened layer is removed at a higher temperature, the removal rate of the hardened layer is increased, and the small amount of hardened layer remaining is quickly removed during the wafer descent process. Then, the hardened layer removal process can reach the end point in advance, shortening the time to remove the hardened layer, thereby improving the degumming efficiency. On the other hand, before the hardened layer removal process reaches the end point, the distance between the wafer and the carrying surface gradually decreases, and the temperature of the wafer increases, so that after the hardened layer removal process reaches the end point, the wafer can quickly heat up to the process temperature corresponding to the uncrosslinked layer removal process, so that it can quickly switch to the uncrosslinked layer removal process, and shorten the heating time required to switch from the hardened layer removal process to the uncrosslinked layer removal process as much as possible, thereby improving the degumming efficiency.

[0070] The removal method disclosed herein may further perform S104 after S103 .

[0071] S104, when the change characteristic quantity corresponding to the current sampling moment meets the termination condition for removing the hardened layer, the wafer is controlled to descend to the carrying surface of the heating base to remove the uncross-linked layer of the photoresist.

[0072] Among them, the change characteristic quantity corresponding to the current sampling moment meets the termination condition of hardened layer removal, which means that the hardened layer is cleaned and the hardened layer removal process reaches the end point.

[0073] The general process of applying the removal method of this embodiment is: when the change characteristic quantity corresponding to the current sampling moment meets the preset conditions, the wafer is controlled to descend from the current position to continue to remove the small amount of remaining hardened layer; then the spectral intensity of the emission light generated by the specific element continues to be obtained. If the change characteristic quantity corresponding to the current sampling moment meets the termination conditions for the removal of the hardened layer, the wafer is controlled to continue to descend to the carrying surface of the heating base, and the temperature of the wafer is increased to 250°C to 300°C to remove the un-cross-linked layer.

[0074] It should be noted that the above-mentioned change characteristic quantity can be understood in a broad sense, as long as it can characterize the change trend of the photoresist removal process.

[0075] In the first implementation, the change characteristic amount may be a change value of the spectral intensity of the emission light generated by a specific element between two adjacent sampling moments. The change characteristic amount may be determined according to the following formula (1), where S(t n ) is the spectral intensity corresponding to the nth sampling moment, n is a positive integer, ΔS n is the change characteristic quantity at the nth sampling moment.

[0076] ΔS n =S(t n )-S(t n-1 ) Formula (I)

[0077] In the second implementation, the change characteristic amount may be the change rate of the spectral intensity of the emission light generated by the specific element between two adjacent sampling moments. The change characteristic amount may be determined according to the following formula (II), where S n ′ is the change characteristic quantity at the nth sampling moment.

[0078] S n ′=[S(t n )-S(t n-1 )] / (t n -t n-1 ) Formula (II)

[0079] In the third implementation, the change characteristic amount may be the rate of decrease of the spectral intensity between two adjacent sampling moments. The change characteristic amount may be determined according to the following formula (III), where Q n is the change characteristic quantity corresponding to the nth sampling moment.

[0080] Q n =[S(t n-1 )-S(t n )]÷S(t n-1 ) Formula (III)

[0081] As the hardening layer removal process is approaching the end in the later stage, the spectral intensity continues to decrease. Therefore, the decrease rate is used to characterize the change feature quantity, which can more conveniently determine whether the change feature quantity meets the preset conditions. n For example, those skilled in the art will obviously understand that the characteristic variable is ΔS after reading the following. n or S n ′’s technical solution.

[0082] As described in this article, the termination condition for hardening layer removal can specifically be that the change characteristic quantity is 0 or close to 0, indicating that the spectral intensity of the specific element has not changed, which means that the gas amount of process gas or reaction gas containing the specific element tends to be stable, and the hardening layer removal process reaches the end point.

[0083] In the removal method disclosed in this article, the preset condition can be set to include that the change feature quantity corresponding to the current sampling moment is greater than a preset value, and the preset value is a non-negative number. In other words, the preset condition satisfies the change feature quantity Q n > 0. Combined with the above, it can be seen that if the change characteristic quantity corresponding to the current sampling moment is a positive number, that is, the spectral intensity decrease rate of the emission light generated by a specific element is greater than 0, which means that the spectral intensity is on the falling edge, it can be shown that the hardening layer removal process is approaching the end point. At this time, the wafer can be controlled to descend to remove the residual hardening layer.

[0084] The value of the preset value can be greater than or equal to 5% and less than or equal to 20%. Taking the preset value of 5% as an example, when the rate of decrease of the spectral intensity between two adjacent sampling moments is equal to 5%, the wafer is controlled to descend. Here, the value of the preset value is an empirical value obtained through a large number of process tests and simulation experiments. At this time, when the method of this embodiment is used to remove the photoresist after ion implantation, the degumming efficiency is high. Of course, the preset value is not limited to 5% to 20%, and can be designed according to actual working conditions.

[0085] The degumming process of controlling the wafer to descend when the hardening layer removal process reaches the end point is compared with the degumming process using the removal method of this embodiment.

[0086] Figure 7 This is a curve relationship diagram of the spectral intensity and sampling time during the debonding process to control the wafer descent when the hardening layer removal process reaches the end point. Figure 8 for Figure 7 The relationship between the height of the wafer relative to the carrier surface and the sampling time during the corresponding degumming process. Figure 7 and Figure 8In the example shown, the degumming process is as follows: first, the wafer is raised to the initial high position, and the height of the wafer relative to the carrying surface is H1, so as to remove the hardened layer; the height of the wafer relative to the carrying surface is controlled to remain at H1; when the sampling time is 105s, the spectrum intensity is detected to reach the maximum value; until the sampling time is 129.95s, the change characteristic quantity Q of the spectrum intensity at the current sampling time is determined n When the temperature is 0%, the termination condition for removing the hardened layer is met, and the wafer is controlled to descend to the carrying surface to remove the uncross-linked layer.

[0087] Fig. 9 This is a curve relationship diagram of the spectral intensity and the sampling time in the process of the degumming process using a removal method provided in an embodiment of the present application. Fig.10 for Fig. 9 The relationship between the height of the wafer relative to the carrier surface and the sampling time during the corresponding degumming process. Fig. 9 and Fig.10 In the example shown, the debonding process is as follows: first, the wafer is raised to the initial high position, and the height of the wafer relative to the carrier surface is H1, so as to remove the hardened layer; the height of the wafer relative to the carrier surface is controlled to remain at H1; when the sampling time is 105s, the spectral intensity reaches the maximum value; until the sampling time is 115s, the change characteristic quantity Q of the spectral intensity at the current sampling time is determined n If the value is greater than the preset value C and the preset conditions are met, the wafer is controlled to descend according to the preset relationship to continue cleaning the residual hardened layer; the spectral intensity is continuously monitored during the descent process until the sampling time is 119.03s, and the change characteristic quantity Q of the spectral intensity at the current sampling time is determined. n When the temperature is 0%, the termination condition for removing the hardened layer is met, and the wafer is controlled to descend to the carrying surface to remove the uncross-linked layer.

[0088] Combination Figures 7 to 10 It can be seen that the removal method of this embodiment controls the wafer to descend to increase the temperature of the wafer when the change characteristic quantity meets the preset conditions and the hardened layer removal process is close to the end point but has not yet reached the end point. The sampling time corresponding to the end point of the hardened layer removal process is shortened from 129.95s to 119.03s, and the termination time of the hardened layer removal process is advanced by 10.92s. This verifies that the removal method of this embodiment can effectively shorten the time for removing the hardened layer, thereby greatly improving the degumming efficiency.

[0089] As disclosed in the removal method, the preset relationship is that the wafer's downward displacement Δh is equal to the product of the downward time Δt and the constant a, a>0. Among them, the constant a can be regarded as the downward speed of the wafer. The downward time Δt refers to the time interval from the start of the decline to the current time, and the decline start time refers to the sampling time corresponding to the change feature quantity meeting the preset conditions.

[0090] Taking the preset value as 5%, the preset condition includes that the change characteristic quantity corresponding to the current sampling moment is greater than 5% as an example. When the change characteristic quantity is greater than 5%, if the sampling duration corresponding to the sampling moment is t1, then when the sampling duration reaches t2, the downward displacement of the wafer is Δh=a*Δt=a*(t2-t1). At this time, the height corresponding to the current position of the wafer is H'=H1-Δh=H1-a*(t2-t1). In this embodiment, when the change characteristic quantity corresponding to the current sampling moment meets the preset conditions, the wafer is controlled to descend at a uniform speed so that the wafer is heated at a uniform speed to reduce the risk of the residual hardened layer bursting during the wafer descent.

[0091] On the basis that the preset condition includes that the change characteristic quantity corresponding to the current sampling moment is greater than the preset value, the preset condition further includes a delay time T between the moment corresponding to the spectral intensity reaching the maximum value and the current sampling moment. That is to say, after the spectral intensity reaches the maximum value, when the interval delay time T is reached and the change characteristic quantity is greater than the preset value, the wafer is controlled to descend according to the preset relationship to remove the hardened layer.

[0092] In the removal method disclosed in this article, when the spectrum intensity reaches the maximum value, the first timer can be used for timing, and when the timing time reaches the delay time T and the change characteristic amount is greater than the preset value, the wafer is controlled to descend. Alternatively, in some alternative embodiments, when the spectrum intensity reaches the maximum value, the time corresponding to the maximum value of the spectrum intensity is obtained, and the time is added to the delay time T to obtain the corresponding descending time point, and when the current time reaches the descending time point and the change characteristic amount is greater than the preset value, the wafer is controlled to descend.

[0093] Therefore, in the removal method of this embodiment, by designing preset conditions including that the change characteristic quantity corresponding to the current sampling moment is greater than the preset value, and the delay time T between the current sampling moment and the moment when the spectrum intensity reaches the maximum value, the spectrum intensity is ensured to be on the falling edge, and when the hardened layer removal process approaches the end point, the wafer is controlled to descend to increase the temperature of the wafer. In this way, while avoiding the popping phenomenon, the hardened layer removal rate can also be increased in the later stage of the hardened layer removal process to shorten the hardened layer removal time, thereby improving the degumming efficiency.

[0094] Fig.11 This is a curve relationship diagram of the spectral intensity and the sampling time in the process of the degumming process using another removal method provided by an embodiment of the present application, Fig.12 for Fig.11 The relationship between the height of the wafer relative to the carrier surface and the sampling time during the corresponding degumming process. Fig.11 and Fig.12In the example shown, the degumming process is as follows: first, the wafer is controlled to rise to the initial high position, and the height of the wafer relative to the carrying surface is H1, so as to remove the hardened layer; the height of the wafer relative to the carrying surface is controlled to remain at H1; when the sampling time is 105s, the spectrum intensity reaches a maximum value, and the first timer is controlled to start timing; when the sampling time is 115s, the timing time of the first timer reaches T, and the change characteristic quantity Q of the spectrum intensity at the current sampling time is determined n If the value is greater than the preset value C, the preset condition is met, and the wafer is controlled to descend according to the preset relationship to continue to clean the residual hardened layer; the spectral intensity is continuously monitored during the descent process until the sampling time is 119.03s, and the change characteristic quantity Q of the spectral intensity at the current sampling time is determined n When the temperature is 0%, the termination condition for removing the hardened layer is met, and the wafer is controlled to descend to the carrying surface to remove the uncross-linked layer.

[0095] Please refer to Figure 7 , Figure 8 , Fig.11 and Fig.12 It can be seen that the removal method of this embodiment is to delay the time length T after the spectral intensity reaches the maximum value and change the characteristic quantity Q n When the temperature of the wafer is greater than the preset value, the wafer is controlled to descend to increase the temperature of the wafer. The sampling time corresponding to the end point of the hardened layer removal process is shortened from 129.95s to 119.03s, and the termination time of the hardened layer removal process is advanced by 10.92s. This verifies that the removal method of this embodiment can effectively increase the hardened layer removal rate, thereby greatly improving the degumming efficiency.

[0096] It should be understood that in an implementation scheme in which the preset conditions also include a delay time T between the moment when the spectral intensity reaches its maximum value and the current sampling moment, if the sampling time corresponding to the moment when the spectral intensity reaches its maximum value is t', the characteristic value of the change during the delay time T is greater than the preset value, and the sampling time corresponding to when the wafer starts to decline is t", then the decline time Δt satisfies: Δt=t”-t'-T. The wafer's downward displacement Δh=a*(t”-t'-T), at this time, the height corresponding to the current position of the wafer is H'=H1-Δh=H1-a*(t”-t'-T).

[0097] The delay time T may be designed based on past experience and needs. For example, the delay time T may be 5s or 10s, and this embodiment does not impose any specific limitation on this.

[0098] In some embodiments of the present application, the delay time T can also be determined by calculation when the spectrum intensity reaches the maximum value. Specifically, the delay time T is calculated according to the following formula (IV). Wherein, T is the delay time; k>0, and k is a constant; Q maxIt is the maximum absolute value of the characteristic quantity of change before the spectral intensity reaches the maximum value.

[0099] T=k / Q max Formula (IV)

[0100] The change characteristic refers to the rate of decrease of the spectral intensity between two adjacent sampling moments. In the early stage of the hardening layer removal process, the spectral intensity continues to increase, that is, the spectral intensity is on the rising edge, and the change characteristic Q n Less than 0, the change characteristic quantity Q n The absolute value of represents the rate of increase of the spectral intensity, and the characteristic quantity Q n The maximum absolute value of can be understood as the maximum rate of change of spectral intensity.

[0101] Therefore, it is understandable that the delay time T and Q max The delay time T is negatively correlated with the rate of increase of the spectral intensity. Specifically, in the early stage of the hardening layer removal process, the faster the spectral intensity increases, the greater the rate of increase of the spectral intensity, and Q max The larger the value, the smaller the delay time T; conversely, in the early stage of the hardening layer removal process, the slower the spectral intensity growth, the smaller the rising rate of the spectral intensity, and Q max The smaller it is, the longer the delay time T is.

[0102] In this way, when the method of this embodiment is used to remove the photoresist, the faster the spectral intensity grows, that is, the greater the rate of the chemical reaction of the hardening layer removal process, the faster the temperature of the wafer can be increased after the change characteristic quantity meets the preset conditions, further ensuring that the temperature of the wafer is increased before reaching the end point of the hardening layer removal process.

[0103] Moreover, compared to directly setting the delay time T as a constant, the delay time T is determined by calculation in the present embodiment, which is conducive to ensuring that for different types of wafers, the delay time T can be adapted to the rising rate of the spectral intensity during the hardening layer removal process, so as to ensure that the hardening layer removal process has not reached the end point when the extended time reaches T from the moment when the spectral intensity reaches the maximum value.

[0104] In addition, in an implementation scheme where the preset condition also includes a delay time T between the time corresponding to the maximum value of the spectrum intensity and the current sampling time, step S102 can be specifically implemented by the following steps.

[0105] S1021, when the spectrum intensity reaches a maximum value, determining the change characteristic quantity of the spectrum intensity corresponding to all sampling moments according to the spectrum intensity corresponding to two adjacent sampling moments.

[0106] S1022: When the absolute value of the characteristic quantity of the change in spectral intensity is greater than the set threshold, execute S103.

[0107] The threshold value is set as a positive number, and the threshold value can be reasonably designed based on actual experience and working conditions. In this embodiment, an additional condition is set for executing step S103, that is, the absolute value of the characteristic quantity of the change in the spectral intensity is greater than the set threshold value. That is, before the spectral intensity reaches the maximum value, in the early stage of the hardening layer removal process, if the growth rate of the spectral intensity is greater than the set threshold value, that is, the growth of the spectral intensity is too fast, then after the spectral intensity reaches the maximum value, the interval delay time T is set, and the characteristic quantity Q is changed. n If it is greater than the preset value, the wafer will be controlled to descend.

[0108] In this way, the method of controlling the wafer to descend after a delay of time T after the spectrum intensity reaches the maximum value is suitable for the situation where the spectrum intensity rises or falls rapidly.

[0109] In any of the above embodiments, preferably, the sampling durations between any two adjacent sampling moments are equal, that is, the spectral intensity of the emission light generated by a specific element is collected every sampling duration Φ, t n -t n-1 =Φ, Φ is a positive constant. Schematically, Φ can be set to 0.1s, 0.5s, 1s, etc. In this way, the spectral intensity can be collected uniformly, especially when the characteristic quantity of change is S n ′, it is also beneficial to simplify the amount of calculation of the changing feature quantity.

[0110] In some embodiments, before the above step S101, the removal method of this embodiment may further include the following steps:

[0111] S201, placing the wafer on the carrying surface of the heating base, and after the preheating time is reached, controlling the wafer to rise to an initial high position.

[0112] Here, the height of the wafer relative to the carrier surface at the initial high position is H1. Figures 9 to 12 , H1 can be specifically 10 mm. Of course, H1 is not limited to 10 mm, and in other embodiments of the present application, it can also be 12 mm, 15 mm, etc.

[0113] In some embodiments of the present application, the specific implementation process of the above step S201 may include the following steps.

[0114] Step S2011: When the process of removing the photoresist after ion implantation begins, the wafer is placed on the carrying surface of the heating base and timing is started.

[0115] Specifically, this step can be achieved by sending a signal to the second timer for timing.

[0116] Step S2012: When the timing time reaches the preheating time, the wafer is controlled to rise from the carrying surface to the initial high position.

[0117] The preheating time d can also be designed based on experience and actual working conditions. For example, Fig.10 and Fig.12 In the example shown, the preheating time d can be specifically designed to be 78 seconds.

[0118] In this embodiment, at the beginning of the hardening layer removal process, the wafer is preheated by placing the wafer on the supporting surface of the heating base within the preheating time d, so that when the wafer moves to the initial high position, it can quickly reach the process temperature of the hardening layer removal process, so that the hardening layer removal process can be carried out as soon as possible, which is beneficial to improve the degumming efficiency.

[0119] Fig.13 A schematic diagram of another method for removing photoresist from a wafer provided in an embodiment of the present application. Fig.13 In a specific example, the removal method includes:

[0120] Step S301: When the process of removing the photoresist after ion implantation begins, the wafer is placed on the carrying surface of the heating base and timing is started.

[0121] Step S302: When the timing time reaches the preheating time d, the lifting assembly is controlled to drive the lifting pins to rise, so that the wafer rises from the carrying surface to the initial high position.

[0122] Step S303: in the process of removing the photoresist after ion implantation, the spectral intensity of the emission light generated by the specific element in the chamber corresponding to different sampling times is obtained.

[0123] Step S303: Determine the change characteristic value Q of the spectral intensity at each sampling moment according to the spectral intensity corresponding to two adjacent sampling moments n .

[0124] Step S304: When the spectrum intensity reaches the maximum value, the delay time T is calculated according to the above formula (IV).

[0125] Step S305: Determine the change characteristic quantity Q at the current sampling time n Whether it is greater than or equal to 5%, and whether there is a delay time T between the current sampling moment and the moment when the spectrum intensity reaches the maximum value; if so, execute step S306; if not, return to execute step S303.

[0126] Step S306: Control the lifting assembly to drive the lifting pins to drive the wafer to descend from the initial high position toward the heating base according to a preset relationship to remove the hardened layer.

[0127] Step S307: Determine the change characteristic quantity Q at the current sampling time nIs it equal to 0%? If so, it is determined that the hardened layer removal process has reached the end point and step S308 is executed; if not, return to step S305.

[0128] Step S308: Control the lifting assembly to drive the lifting pins to drive the wafer down to the carrying surface of the heating base to remove the uncross-linked layer.

[0129] It is to be understood that the above embodiments are merely exemplary embodiments used to illustrate the principles of the present invention, but the present invention is not limited thereto. For those of ordinary skill in the art, various modifications and improvements can be made without departing from the spirit and essence of the present invention, and these modifications and improvements are also considered to be within the scope of protection of the present invention.

Claims

1. A method for removing photoresist on a wafer, characterized in that: The removal method comprises: In the process of removing the photoresist after ion implantation, the spectral intensity of the emission light generated by a specific element in the chamber corresponding to different sampling times is obtained; Determining a change characteristic amount of the spectral intensity at each of the sampling moments according to the spectral intensities corresponding to two adjacent sampling moments; When the change characteristic quantity corresponding to the current sampling moment meets the preset conditions, it is determined that the hardened layer removal process is close to the end point and the wafer is controlled to descend from the current position toward the heating base according to a preset relationship to remove the hardened layer of the photoresist.

2. The removal method according to claim 1, characterized in that: The change characteristic is the rate of decrease of the spectral intensity between two adjacent sampling moments, and the change characteristic satisfies the following relationship: Q n =[S(t n-1 )-S(t n )]÷S(t n-1 ), where Q n is the change characteristic quantity corresponding to the nth sampling moment, S(t n ) is the spectral intensity corresponding to the nth sampling moment, and n is a positive integer.

3. The removal method according to claim 2, characterized in that: The preset condition includes that the change characteristic quantity corresponding to the current sampling moment is greater than a preset value, and the preset value is a non-negative number.

4. The removal method according to claim 3, characterized in that: The preset value is greater than or equal to 5% and less than or equal to 20%.

5. The removal method according to claim 3, characterized in that: The preset condition also includes the delay time between the time when the spectrum intensity reaches the maximum value and the current sampling time.

6. The removal method according to claim 5, characterized in that: The delay duration is calculated according to the following relationship: T=k / Q max ; Wherein, T is the delay time; k>0, and k is a constant; Q max It is the maximum value of the absolute value of the change characteristic quantity before the spectral intensity reaches the maximum value.

7. The removal method according to any one of claims 1 to 6, characterized in that: The preset relationship is that the falling displacement Δh of the wafer is equal to the product of the falling time Δt and a constant a, and a is greater than 0.

8. The removal method according to any one of claims 1 to 6, characterized in that: Before obtaining the spectral intensity of the emission light generated by the specific element in the chamber corresponding to different sampling times, the removal method further includes: The wafer is placed on the carrying surface of the heating base, and after the preheating time is reached, the wafer is controlled to rise to an initial high position.

9. The removal method according to any one of claims 1 to 6, characterized in that: After controlling the wafer to descend from the current position toward the heating base according to a preset relationship to remove the hardened layer of the photoresist, the method further includes: When the change characteristic quantity corresponding to the current sampling moment meets the termination condition for removing the hardened layer, the wafer is controlled to descend to the carrying surface of the heating base to remove the uncross-linked layer of the photoresist.

10. A semiconductor process equipment, characterized in that: include: Chamber; A heating base is disposed in the chamber and has a carrying surface for carrying the wafer; A controller comprises at least one processor and at least one memory, wherein the memory stores a computer program, and the processor executes the computer program to perform the removal method according to any one of claims 1 to 9.

Images