Semiconductor processing apparatus and pulsed plasma method thereof

Abstract

The application discloses a semiconductor process equipment and a pulse-regulated plasma method thereof, and belongs to the technical field of semiconductor processes. The pulse-regulated plasma method comprises the following steps: setting a first pulse to control synchronous opening and closing of a high-frequency radio frequency power supply and a low-frequency radio frequency power supply through the first pulse; setting a second pulse to sequentially form a plurality of different power control periods in each radio frequency cycle of the low-frequency radio frequency power supply through the second pulse; and adjusting power amplitude of the high-frequency radio frequency power supply to different power values in the different power control periods to regulate plasma of the semiconductor process equipment. According to the technical scheme, the power amplitude of the high-frequency radio frequency power supply in different stages is changed to form different pulse modes in each radio frequency cycle of the low-frequency radio frequency power supply, so that different etching requirements of products can be met.

Description

Technical Field

[0001] The present application belongs to the field of semiconductor process technology, and in particular relates to a semiconductor process equipment and a pulsed plasma regulation method thereof. Background Art

[0002] According to Morgan's Law, the number of transistors on a chip of the same area doubles every 18-24 months. Therefore, chip processing has become more and more sophisticated, the chip etching line width has continued to decrease, and the problem of plasma induced damage (PID) has become more and more prominent. In order to achieve separate control of plasma density and energy, two RF power supplies of different frequencies are usually used in capacitively coupled plasma (CCP) etching, that is, a high-frequency RF power supply is used to control the plasma density, and a low-frequency RF power supply is used to control the plasma energy. However, since these RF power supplies are all traditional continuous wave (CW) RF sources, they will cause large plasma-induced damage to the surface of the etched material during etching, which cannot meet the current etching process requirements. For this reason, synchronized pulse technology was invented. Subsequently, in order to improve the plasma process window of synchronized pulse technology, level-level synchronized pulse technology was invented based on synchronized pulse technology.

[0003] However, both synchronized pulse technology and level-level synchronized pulse technology can adjust plasma parameters by changing the pulse frequency and duty cycle to reduce plasma-induced damage. However, since the power variation period of their high-frequency RF power supplies is based on the period of the synchronized pulse, and the pulse period of the synchronized pulse is generally equivalent to dozens or even thousands of RF cycles, the power variation period of the high-frequency RF power supplies in these technologies will be dozens or even thousands of RF cycles. This will further limit the power variation methods of the high-frequency RF power supplies and make them unable to meet the more extensive etching requirements of products. Summary of the Invention

[0004] The embodiments of the present application provide a semiconductor process equipment and a pulse-regulated plasma method thereof, aiming to solve the technical problem that the power variation cycle of the high-frequency RF power supply in the existing pulse-regulated plasma method is dozens or even thousands of RF cycles, which limits the power variation mode of the high-frequency RF power supply and makes it impossible to meet more etching requirements of the product.

[0005] In a first aspect, an embodiment of the present application provides a method for pulse-regulated plasma in a semiconductor process device, wherein the semiconductor process device includes a high-frequency radio frequency power supply and a low-frequency radio frequency power supply for plasma etching, and the pulse-regulated plasma method includes the following steps:

[0006] Setting a first pulse to control the high-frequency radio frequency power supply and the low-frequency radio frequency power supply to be synchronously switched on and off by the first pulse;

[0007] Setting a second pulse so as to sequentially form a plurality of different power control periods in each radio frequency cycle of the low-frequency radio frequency power supply through the second pulse;

[0008] During different power control periods, the power amplitude of the high-frequency radio frequency power supply is adjusted to different power values ​​to regulate the plasma of the semiconductor process equipment.

[0009] Optionally, in some embodiments, the frequency range of the high-frequency RF power supply is greater than 40 MHz, and the frequency range of the low-frequency RF power supply is 200 kHz to 3.2 MHz.

[0010] Optionally, in some embodiments, the multiple different power control periods are sequentially a first power control period, a second power control period, a third power control period, and a fourth power control period;

[0011] The first power control period corresponds to the period when the power of the low-frequency RF power source changes from zero to a maximum positive voltage;

[0012] The second power control period corresponds to the period when the power of the low-frequency RF power source changes from a maximum positive voltage to a zero value;

[0013] The third power control period corresponds to the period when the power of the low-frequency RF power source changes from zero to a maximum negative voltage;

[0014] The fourth power control period corresponds to a period when the power of the low-frequency RF power source changes from a negative voltage maximum value to a zero value.

[0015] Optionally, in some embodiments, the duration of the first power control period and the duration of the second power control period are both less than 1 / 4 of the RF cycle of the low-frequency RF power supply, and the duration of the first power control period is less than the duration of the second power control period; and / or,

[0016] The sum of the duration of the third power control period and the duration of the fourth power control period is greater than 1 / 2 of the RF cycle of the low-frequency RF power supply, and the duration of the third power control period is less than the duration of the fourth power control period.

[0017] Optionally, in some embodiments, the step of adjusting the power amplitude of the high-frequency RF power supply to different power values ​​in different power control periods includes:

[0018] During the first power control period, the power amplitude of the high-frequency radio frequency power supply is adjusted to a first power value;

[0019] adjusting the power amplitude of the high frequency RF power source to a second power value in the second power control period;

[0020] adjusting the power amplitude of the high frequency RF power source to a third power value in the third power control period;

[0021] adjusting the power amplitude of the high frequency RF power source to a fourth power value in the fourth power control period.

[0022] Optionally, in some embodiments, the first power value is equal to an initial power value of the high frequency RF power source, the second power value, the third power value and the fourth power value are all less than the initial power value of the high frequency RF power source, and the second power value is the smallest among the second power value, the third power value and the fourth power value.

[0023] Optionally, in some embodiments, the first power value and the second power value are both in a first power value interval, the third power value and the fourth power value are both in a second power value interval, and the first power value interval is smaller than the second power value interval.

[0024] Optionally, in some embodiments, the first power value and the second power value are both in a third power value interval, the third power value and the fourth power value are both in a fourth power value interval, and the third power value interval is larger than the fourth power value interval.

[0025] In a second aspect, embodiments of the present application provide a semiconductor process equipment, comprising a RF device and a process chamber, the process chamber having a first electrode and a second electrode oppositely arranged, the first electrode being grounded, the RF device being connected to the second electrode, and the RF device being configured to perform the pulse-regulated plasma method as described above.

[0026] Optionally, in some embodiments, the RF device comprises a high frequency RF power source, a low frequency RF power source, a low pass filter, a clock signal generator, a pulse controller and a synchronization signal generator;

[0027] the low frequency RF power source and the high frequency RF power source are respectively connected to the second electrode;

[0028] the clock signal generator is respectively connected to the low frequency RF power source and the synchronization signal generator, the synchronization signal generator is connected to the pulse controller, and the pulse controller is respectively connected to the high frequency RF power source and the low frequency RF power source.

[0029] In the present application, when the high-frequency RF power supply and the low-frequency RF power supply of the semiconductor process equipment perform plasma etching, on the one hand, a first pulse is set to control the high-frequency RF power supply and the low-frequency RF power supply to be synchronously turned on and off (including synchronous opening and synchronous closing) through the first pulse. This process is the same as the existing synchronous pulse technology. On the other hand, a second pulse is set to form a plurality of different power control periods in each RF cycle of the low-frequency RF power supply through the second pulse, and the power amplitude of the high-frequency RF power supply is adjusted to different power values ​​in different power control periods to regulate the plasma of the semiconductor process equipment. In this way, the present technical solution can focus on the plasma state change within a RF cycle of the low-frequency RF power supply, that is, the power amplitude of the high-frequency RF power supply (i.e., the amplitude of the incident power) is set according to the multiple different states of the plasma within a RF cycle of the low-frequency RF power supply, so as to form different pulse modes by changing the power amplitude of the high-frequency RF power supply at different stages to meet the different etching requirements of the product. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] The following detailed description of the specific embodiments of the present application in conjunction with the accompanying drawings will make the technical solutions and beneficial effects of the present application apparent.

[0031] Figure 1 It is the first principle intention of existing synchronous pulse technology.

[0032] Figure 2 It is the second principle intention of existing synchronous pulse technology.

[0033] Figure 3 This is a flow chart of a pulsed plasma regulation method for semiconductor process equipment provided in an embodiment of the present application.

[0034] Figure 4 yes Figure 1 A first principles illustration of the pulsed plasma method is shown.

[0035] Figure 5 yes Figure 1 A second principle illustration of the pulsed plasma method is shown.

[0036] Figure 6 yes Figure 1 A third principle illustration of the pulsed plasma method is shown.

[0037] Figure 7 It is a structural schematic diagram of the semiconductor process equipment provided in an embodiment of the present application. DETAILED DESCRIPTION

[0038] The following, in conjunction with the accompanying drawings, clearly and completely describes the technical solutions 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. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without making creative work are within the scope of protection of this application. In the absence of conflict, the following embodiments and their technical features can be combined with each other.

[0039] According to Morgan's Law, the number of transistors on a chip of the same area doubles every 18-24 months. Therefore, chip processing has become more and more sophisticated, the chip etching line width has continued to decrease, and the problem of plasma induced damage (PID) has become more and more prominent. In order to achieve separate control of plasma density and energy, two RF power supplies of different frequencies are usually used in capacitively coupled plasma (CCP) etching, that is, a high-frequency RF power supply is used to control the plasma density, and a low-frequency RF power supply is used to control the plasma energy. However, since these RF power supplies are all traditional continuous wave (CW) RF sources, they will cause large plasma-induced damage to the surface of the etched material during etching, which cannot meet the current etching process requirements. For this reason, synchronized pulse technology was invented. Subsequently, in order to improve the plasma process window of synchronized pulse technology, level-level synchronized pulse technology was invented based on synchronized pulse technology.

[0040] Related technology 1: Synchronous pulse technology is mainly reflected in the addition of a pulse synchronization signal between two RF power sources of different frequencies, which provides an additional control device for the on-off of the RF power source, thereby expanding the control window of plasma parameters and improving the flexibility of process control. Figure 1 As shown, by changing the pulse frequency and duty cycle, the purpose of adjusting the plasma parameters can be achieved. This is because, during the etching process, the positive ions that play an etching role will adhere to the bottom of the groove. Since like charges repel each other, the positive ions that subsequently enter the groove will be repelled by the accumulated positive charge at the bottom of the groove, and the movement path will change, resulting in an abnormal etching profile. Synchronous pulse technology uses the on and off of the pulse to reduce the ignition time. At the same time, during the pulse off period, the charge accumulated at the bottom of the groove can be effectively neutralized to improve the etching morphology. In addition, it also avoids damage to the wafer caused by long-term ion bombardment. However, since the existing synchronous pulse technology only achieves the purpose of plasma parameter adjustment by controlling the on and off of the RF power supply, and the pulse period is generally equivalent to dozens or even thousands of RF cycles, this will make the power change period of the high-frequency RF power supply in the synchronous pulse technology dozens or even thousands of RF cycles, which in turn makes the power change mode of the high-frequency RF power supply limited, resulting in an inability to meet more etching requirements of the product.

[0041] Related Technology 2: The invention of Level-Level Synchronous Pulse Technology is based on synchronous pulse technology. It only reduces the incident power of the high-frequency RF power supply during the low-level pulse period, but the power still exists, so that the plasma will not be extinguished during the pulse off period, thereby expanding the usable process window. At the same time, during the pulse off period, the movement of free radicals is enhanced, and they can accumulate on the sidewalls of the etched grooves to form a protective layer, effectively protecting the groove sidewalls and further improving the etching morphology. However, the power of the high-frequency RF power supply of Level-Level Synchronous Pulse Technology is also tens or even thousands of RF cycles. Therefore, there is still a problem that the power variation of the high-frequency RF power supply is limited, resulting in an inability to meet the product's more extensive etching requirements.

[0042] Based on this, it is necessary to provide a new solution for the pulse-regulated plasma method to solve the technical problem that the power change cycle of the high-frequency RF power supply in the existing pulse-regulated plasma method is dozens or even thousands of RF cycles, which makes the power change mode of the high-frequency RF power supply limited, resulting in the inability to meet more etching requirements of the product.

[0043] In one embodiment, Figure 3 As shown, an embodiment of the present application provides a method for pulse-regulated plasma in a semiconductor process device. The semiconductor process device may include a high-frequency radio frequency power supply and a low-frequency radio frequency power supply for plasma etching. The pulse-regulated plasma method includes the following steps:

[0044] Step S110: setting a first pulse to control the high-frequency RF power supply and the low-frequency RF power supply to be synchronously switched on and off by the first pulse.

[0045] It is understandable that the pulsed plasma regulation method of the embodiment of the present application is a further improvement based on the existing synchronous pulse technology. Figure 4 As shown, a first pulse identical to the synchronous pulse of the existing synchronous pulse technology is set to control the high-frequency RF power supply and the low-frequency RF power supply to be synchronously turned on and off by the first pulse, that is, when the first pulse switches from a low level to a high level, the high-frequency RF power supply and the low-frequency RF power supply are controlled to be synchronously turned on, and when the first pulse switches from a high level to a low level, the high-frequency RF power supply and the low-frequency RF power supply are controlled to be synchronously turned off, so as to utilize the on and off of the first pulse to reduce the ignition time. At the same time, during the off period of the first pulse, the charge accumulated at the bottom of the groove can be effectively neutralized to improve the etching morphology. In addition, it also avoids damage to the chip caused by long-term ion bombardment.

[0046] Step S120: setting a second pulse, so as to sequentially form a plurality of different power control periods in each radio frequency cycle of the low-frequency radio frequency power supply through the second pulse.

[0047] It is understandable that if Figure 4 As shown, the second pulse is a pulse added to the pulse-regulated plasma method of an embodiment of the present application on the basis of the existing synchronous pulse technology, so that while the first pulse controls the high-frequency RF power supply and the low-frequency RF power supply to be synchronously switched on and off, a plurality of different power control periods are sequentially formed by the second pulse within each RF cycle of the low-frequency RF power supply, that is, one pulse cycle of the second pulse is equal to one RF cycle of the low-frequency RF power supply, and the second pulse can undergo four level changes of different durations within one pulse cycle to form a plurality of different power control periods accordingly.

[0048] Step S130: During different power control periods, the power amplitude of the high-frequency radio frequency power supply is adjusted to different power values ​​to regulate the plasma of the semiconductor process equipment.

[0049] It can be understood that, after the above-mentioned method steps are used to sequentially form multiple different power control periods in each RF cycle of the low-frequency RF power supply through the second pulse, that is, the second pulse can undergo four level changes of different durations within one pulse cycle, each level change of the second pulse can be used as a response basis for changing the power amplitude of the high-frequency RF power supply (i.e., the amplitude of the incident power), and the power amplitude of the high-frequency RF power supply can be adjusted to different power values ​​in different power control periods, thereby regulating the plasma of the semiconductor process equipment.

[0050] In this way, in the embodiment of the present application, the focus can be on the changes in the plasma state within one RF cycle of the low-frequency RF power supply, that is, the power amplitude of the high-frequency RF power supply (that is, the amplitude of the incident power) is set according to the various different states of the plasma within one RF cycle of the low-frequency RF power supply, so as to form different pulse modes by changing the power amplitude of the high-frequency RF power supply at different stages to meet the different etching requirements of the product.

[0051] In some examples, such as Figure 4 As shown, the above-mentioned multiple different power control periods are, in sequence, a first power control period A, a second power control period B, a third power control period C, and a fourth power control period D. The first power control period A corresponds to a period when the power of the low-frequency RF power supply changes from zero to a positive voltage maximum. The second power control period B corresponds to a period when the power of the low-frequency RF power supply changes from a positive voltage maximum to zero. The third power control period C corresponds to a period when the power of the low-frequency RF power supply changes from zero to a negative voltage maximum. The fourth power control period D corresponds to a period when the power of the low-frequency RF power supply changes from a negative voltage maximum to zero.

[0052] It is understandable that in the existing synchronous pulse technology, as the incident power of the low-frequency RF power source changes, the plasma has roughly four states within one RF cycle of the low-frequency RF power source, such as Figure 2 As shown in Figure 1, the first stage is the sheath collapse phase (corresponding to the first power control period A in this example). During this phase, the chip voltage is positive and high, and the electron mass is small, making it easily accelerated by the electric field. Electrons near the chip are accelerated toward the chip. At this time, the electron current flowing into the electrode is large, and the plasma impedance is minimum in this phase. The second stage is the mixing phase (corresponding to the second power control period B in this example). During this phase, the chip voltage is still positive, but electrons near the chip collide with the positively charged chip and annihilate, leaving only ions around the chip. The ions are large and difficult to accelerate by the electric field. At this time, the current around the chip is mainly ionic current, which is small. Therefore, the plasma impedance is maximum. During the transition from the first stage to the second stage, the plasma impedance changes dramatically, making it difficult for the matching device to quickly complete the matching. Therefore, the reflected power of the high-frequency RF power supply increases rapidly during the transition. The third stage is the sheath expansion phase (corresponding to the third power control period C in this example). During this phase, the chip voltage is negative, and positive ions are attracted to the chip and move toward the chip. Electrons at the edge of the sheath are accelerated toward the upper electrode. Because the ion mobility is much smaller than the electron mobility, the ion current is small, and the plasma impedance is also relatively small. The fourth stage is the sheath contraction period (corresponding to the fourth power control period D in this example). Since the positive ions in the third stage move toward the chip surface, a certain amount of positive charge accumulation is generated on the chip surface. At this time, the electrons at the edge of the sheath are attracted by the positive ions and approach the chip, and the plasma impedance is relatively large.

[0053] It can be seen that the first power control period A, the second power control period B, the third power control period C and the fourth power control period D in this example can be well fitted with the duration of the four plasma states within one RF cycle of the low-frequency RF power supply, so as to better make corresponding changes to the power amplitude of the high-frequency RF power supply to better meet the corresponding etching requirements of the product.

[0054] At the same time, based on the above statement and Figure 2 As shown in the figure, the plasma impedance changes greatly within one RF cycle of the low-frequency RF power supply, and it is difficult for the matcher to complete multiple matching within one RF cycle. Therefore, during the process of the plasma switching between the four states, the reflected power of the high-frequency RF power supply increases accordingly. In other words, the existing synchronous pulse technology cannot solve the problem of excessive reflected power caused by intermodulation distortion (IMD) during the etching process. The so-called intermodulation distortion refers to the interaction of various spectral components in the nonlinear impedance when multiple frequency signals are input, generating new spectral components. Assuming the high-frequency frequency is f h , the low frequency is f l , then the frequency of the new spectral component generated by IMD is mfh +nf l Wherein, m is a positive integer, n is an integer. Since the frequency of the new spectral component often exceeds the operating frequency range of the matching device, the matching device cannot perform impedance matching on the frequency of the new spectral component generated by the IMD, which results in a large reflected power of the new spectral component (while the frequency of the initial spectrum can be identified and impedance matched by the matching device, so the reflected power of the initial spectrum is small). High reflected power not only affects the power feeding efficiency, and in severe cases, it may exceed the upper limit of the reflected power of the high-frequency RF power supply, affecting the high-frequency RF power supply. Therefore, by setting the first power control period A, the second power control period B, the third power control period C and the fourth power control period D, the duration of the four states of the plasma in one RF cycle of the low-frequency RF power supply can be better matched, so as to better change the power amplitude of the high-frequency RF power supply to solve the problem of high reflected power caused by IMD.

[0055] In some examples, the frequency range of the high-frequency RF power supply is greater than 40MHz, and the frequency range of the low-frequency RF power supply is 200kHz-3.2MHz. Because the embodiment of the present application needs to complete multiple changes of the power amplitude of the high-frequency RF power supply in each RF cycle of the low-frequency RF power supply, the frequency of the high-frequency RF power supply and the frequency of the low-frequency RF power supply need to be selected in a suitable interval to ensure that the high-frequency RF power supply can successfully complete multiple changes of the power amplitude in each RF cycle of the low-frequency RF power supply. At the same time, in the case where the frequency of the high-frequency RF power supply and the frequency of the low-frequency RF power supply are similar, such as 40.68MHz and 13.56MHz, the new spectrum generated by the intermodulation distortion (IMD) cannot pass through the filter because the difference between the initial high-frequency RF power supply frequency and the new spectrum frequency is too large, so the influence of the reflected power caused by the IMD does not need to be considered.

[0056] Further, the duration of the first power control period A and the duration of the second power control period B are both less than 1 / 4 of the RF cycle of the low-frequency RF power supply, and the duration of the first power control period A is less than the duration of the second power control period B. The sum of the duration of the third power control period C and the duration of the fourth power control period D is greater than 1 / 2 of the RF cycle of the low-frequency RF power supply, and the duration of the third power control period C is less than the duration of the fourth power control period D, so that it can better match the duration of the four states of the plasma in one low-frequency RF cycle, so as to better change the power amplitude of the high-frequency RF power supply to better meet the corresponding etching requirements of the product.

[0057] In some examples, the multiple different power control periods are, in order, a first power control period A, a second power control period B, a third power control period C, and a fourth power control period D. The specific process of executing the above method step "adjusting the power amplitude of the high-frequency RF power supply to different power values ​​in different power control periods" is as follows: in the first power control period A, the power amplitude of the high-frequency RF power supply is adjusted to a first power value. In the second power control period B, the power amplitude of the high-frequency RF power supply is adjusted to a second power value. In the third power control period C, the power amplitude of the high-frequency RF power supply is adjusted to a third power value. In the fourth power control period D, the power amplitude of the high-frequency RF power supply is adjusted to a fourth power value.

[0058] In this way, different pulse modes can be formed by reasonably adjusting the value ranges of the first power value, the second power value, the third power value and the fourth power value to meet different etching requirements of the product.

[0059] In some examples, such as Figure 4As shown, the first power value can be specifically equal to the initial power value of the high-frequency RF power source, and the second power value, the third power value, and the fourth power value are all less than the initial power value of the high-frequency RF power source, with the second power value being the smallest among the second, third, and fourth power values. In this case, a first pulse mode can be formed. In the first pulse mode, during the first power control period A, where the plasma impedance is lowest, the power amplitude of the high-frequency RF power source (i.e., the amplitude of the incident power) remains the same as in the prior art (i.e., both are at the initial power value). During the second power control period B, where the plasma impedance is highest, the power amplitude of the high-frequency RF power source (i.e., the amplitude of the incident power) is significantly reduced to a minimum value. During the third power control period C and the fourth power control period D, where the plasma impedance is lower than that of the first power control period A, the power amplitude of the high-frequency RF power source (i.e., the amplitude of the incident power) is also significantly reduced compared to the first power control period A. This results in the third power value and the fourth power value both being less than the initial power value of the high-frequency RF power source (and both being higher than the second power value). Preferably, the fourth power value is less than the third power value, and the third power value is less than half the initial power value of the high-frequency RF power source. This ensures that the power amplitude (i.e., the amplitude of the incident power) of the high-frequency RF power source is significantly reduced during the third power control period C and the fourth power control period D relative to the first power control period A. Because semiconductor process equipment performs plasma etching with varying gas, pressure, and RF power within the process chamber, as well as varying plasma states and impedance, the specific values ​​of the second, third, and fourth power values ​​can be determined based on the current gas, pressure, and RF power within the process chamber, provided that the aforementioned conditions are met. In this way, the first pulse mode of this example can reduce the reflected power of the high-frequency RF power supply in the second power control period B, the third power control period C and the fourth power control period D (i.e., the amplitude of the incident power) by respectively reducing the power amplitude of the second power control period B, the third power control period C and the fourth power control period D, thereby significantly reducing the reflected power caused by IMD, reducing the overall reflected power, increasing the power feeding efficiency, and reducing the risk of damage to the RF power supply due to reflected power, so as to meet the product's higher etching requirements for solving the problem of excessive reflected power caused by IMD.

[0060] In some examples, such as Figure 5As shown, the first power value and the second power value are both within the first power value interval, and the third power value and the fourth power value are both within the second power value interval, wherein the first power value interval is smaller than the second power value interval. Furthermore, the first power value interval may specifically be a power value interval that is less than 1 / 4 of the initial power value of the high-frequency RF power supply. In this case, the first power value and the second power value may be equal and both are less than 1 / 4 of the initial power value of the high-frequency RF power supply. The second power value interval may specifically be a power value interval in which the difference from the initial power value of the high-frequency RF power supply is less than a preset threshold. In this case, the third power value and the fourth power value may be equal and both are equal to the initial power value of the high-frequency RF power supply. In this way, a second pulse mode can be formed. In the second pulse mode, the power amplitude of the first power control period A and the second power control period B (i.e., the amplitude of the incident power) is reduced relative to the initial power value, and the power amplitude of the third power control period C and the fourth power control period D (i.e., the amplitude of the incident power) remains unchanged at the initial power value, that is, when the chip surface is negatively charged, the power values ​​of the third power control period C and the fourth power control period D are greatly increased relative to the first power control period A and the fourth power control period B, and the positive ions move toward the chip surface. At this time, the ion energy is larger and the electron energy is smaller, which can effectively increase the plasma etching rate, and can meet the etching requirements of the product that is insensitive to ion damage and pursues etching rate.

[0061] In some examples, such as Figure 6As shown, the first power value and the second power value are equal and both fall within the third power value interval, and the third power value and the fourth power value are both within the fourth power value interval, with the third power value interval being greater than the fourth power value interval. Furthermore, the third power value interval can specifically be a power value interval in which the difference from the initial power value of the high-frequency RF power supply is less than a preset threshold. In this case, the first power value and the second power value can be equal and both equal to the initial power value of the high-frequency RF power supply. The fourth power value interval can specifically be a power value interval that is less than 1 / 4 of the initial power value of the high-frequency RF power supply. In this case, the third power value and the fourth power value can be equal and both less than 1 / 4 of the initial power value of the high-frequency RF power supply. In this way, a third pulse mode can be formed. Under the third pulse mode, the power amplitudes of the first power control period A and the second power control period B (i.e., the amplitude of the incident power) maintain the initial power value unchanged, and the power amplitudes of the third power control period C and the fourth power control period D (i.e., the amplitude of the incident power) are reduced relative to the initial power value, that is, when the chip surface is positively charged, the power values ​​of the first power control period A and the second power control period B are greatly increased relative to the third power control period C and the fourth power control period D. At this time, polymer deposition and the offset of the accumulated positive charges in the grooves are carried out. Compared with the existing technology, the etching profile can be greatly improved (etching profile refers to the shape of the etching groove. During etching, especially deep hole etching, we hope that the etching groove wall is deep and straight, and long-term ignition will cause excessive accumulation of positive charge at the bottom of the groove. Due to the repulsion of like charges, the motion trajectory of the positive ions entering the groove later will be offset. The groove wall will also become curved. Improvement means that the accumulated charge is offset, and the ions can reach the bottom of the groove straightly for etching. This is the so-called improved etching profile), which can meet the etching needs of products with high requirements for etching profile and no pursuit of etching rate.

[0062] In addition, the examples of this application can even adopt different pulse modes in different process stages of the product, so as to present different process effects through the combination of several pulse modes, thereby meeting more etching requirements of the product. For example: when the reflected power will not damage the RF power supply and the etching profile and etching rate are not extremely pursued, the second pulse mode and the third pulse mode can be combined, and the second pulse mode and the third pulse mode can be interspersed, such as three second pulse modes plus three third pulse modes are used in a cycle, which can improve the etching profile while maintaining a certain etching rate. However, it is not recommended to use the first pulse mode at the same time as the second pulse mode or the third pulse mode.

[0063] In one embodiment, Figure 6As shown, an embodiment of the present application further provides a semiconductor process equipment 1, which includes a radio frequency device 100 and a process chamber 200. The process chamber 200 has a first electrode 210 and a second electrode 220 placed opposite to each other. The first electrode 210 is grounded, and the radio frequency device 100 is connected to the second electrode 220. When the radio frequency device 100 is working, the pulse-regulated plasma method in the above embodiment is performed, which will not be repeated here.

[0064] It is understood that the RF device 100 may specifically include a high-frequency RF power supply 101, a low-frequency RF power supply 104, a clock signal generator 108, a pulse controller 109, and a synchronization signal generator 110. The low-frequency RF power supply 104 and the high-frequency RF power supply 101 are connected to the second electrode 220. The clock signal generator 108 is respectively connected to the low-frequency RF power supply 104 (specifically, its clock output terminal) and the synchronization signal generator 110. The synchronization signal generator 110 is connected to the pulse controller 109. The pulse controller 109 is respectively connected to the high-frequency RF power supply 101 and the low-frequency RF power supply 104. Furthermore, the RF device 100 may also specifically include a high-pass filter 102, a high-frequency matcher 103, a low-pass filter 105, a low-frequency matcher 106, and a directional coupler 107. In this case, the low-frequency RF power supply 104 may be connected to the second electrode 220 in sequence through the low-frequency matcher 106 and the low-pass filter 105. The high-frequency RF power source 101 may be connected to the second electrode 220 through the directional coupler 107 , the high-frequency matcher 103 and the high-pass filter 102 in sequence, and the directional coupler 107 is further connected to the synchronization signal generator 110 .

[0065] As can be seen, the RF device 100 of the embodiment of the present application connects a directional coupler 107 between the synchronization signal generator 110 and the high-frequency RF power supply 101, which can prevent the large reflected power generated by IMD on the high-frequency side from affecting the pulse signal of the synchronization signal generator 110. At the same time, the clock signal generator 108 of the present application is connected to the clock output terminal of the low-frequency RF power supply 104 to set more than four power types for the high-frequency RF power supply 101 based on the phase of the low-frequency RF power supply 104. The synchronization signal generator 110 is connected to the pulse controller 109 to generate the corresponding synchronization pulse signal. The pulse controller 109 is respectively connected to the high-frequency RF power supply 101 (specifically, to its pulse input terminal) and the low-frequency RF power supply 104 (specifically, to its pulse input terminal), and generates two pulse signals. Among them, the first pulse signal has the same function as that in the synchronous pulse technology, and is used to control the synchronous on and off of the high-frequency RF power supply 101 and the low-frequency RF power supply 104. The second pulse signal realizes the control of the change of the power amplitude (i.e., the amplitude of the incident power) of the high-frequency RF power supply 101 in each RF cycle of the low-frequency RF power supply 104.

[0066] In this way, in the embodiment of the present application, the semiconductor process equipment 1 can focus on the changes in the plasma state within one RF cycle of the low-frequency RF power supply 104, that is, the power amplitude of the high-frequency RF power supply 101 (that is, the amplitude of the incident power) is set according to the various different states of the plasma within one RF cycle of the low-frequency RF power supply 104, so as to form different pulse modes by changing the power amplitude of the high-frequency RF power supply 101 at different stages to cope with different etching requirements of the product, and even different pulse modes can be used in different process stages of the product to present different process effects through the combination of several pulse modes, thereby meeting more etching requirements of the product.

[0067] Although the present application has been shown and described with respect to one or more implementations, equivalent variations and modifications will occur to those skilled in the art based on reading and understanding this specification and the accompanying drawings. The present application includes all such modifications and variations and is limited only by the scope of the appended claims. In particular, with respect to the various functions performed by the above-mentioned components, the terms used to describe such components are intended to correspond to any component (unless otherwise indicated) that performs the specified function of the component (e.g., it is functionally equivalent), even if it is not structurally equivalent to the disclosed structure that performs the function in the exemplary implementation of this specification shown herein.

[0068] That is, the above description is merely an embodiment of the present application and does not limit the patent scope of the present application. Any equivalent structural or equivalent process transformations made using the contents of the description and drawings of this application, such as the mutual combination of technical features between the various embodiments, or direct or indirect application in other related technical fields, are also included in the patent protection scope of the present application.

[0069] In addition, in the description of the present application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present application. In addition, for structural elements with the same or similar characteristics, the present application may use the same or different reference numerals to identify them. In addition, the terms "first" and "second" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more features. In the description of the present application, "multiple" means two or more, unless otherwise clearly and specifically defined.

[0070] In this application, the word "exemplary" is used to mean "serving as an example, illustration or description". Any embodiment described in this application as "exemplary" is not necessarily to be construed as being more preferred or more advantageous than other embodiments. The above description is provided to enable any person skilled in the art to implement and use the present application. In the above description, various details are listed for the purpose of explanation. It should be understood that a person of ordinary skill in the art can recognize that the present application can be implemented without using these specific details. In other embodiments, well-known structures and processes will not be elaborated in detail to avoid obscuring the description of the present application with unnecessary details. Therefore, the present application is not intended to be limited to the embodiments shown, but is consistent with the widest scope consistent with the principles and features disclosed in this application.

Claims

1. A method for pulse-regulated plasma in semiconductor processing equipment, wherein the semiconductor processing equipment includes a high-frequency radio frequency power supply and a low-frequency radio frequency power supply for plasma etching, characterized in that: The pulsed plasma method comprises the following steps: Setting a first pulse to control the high-frequency radio frequency power supply and the low-frequency radio frequency power supply to be synchronously switched on and off by the first pulse; Setting a second pulse so as to sequentially form a plurality of different power control periods in each radio frequency cycle of the low-frequency radio frequency power supply through the second pulse; During different power control periods, the power amplitude of the high-frequency radio frequency power supply is adjusted to different power values ​​to regulate the plasma of the semiconductor process equipment.

2. The pulsed plasma method according to claim 1, wherein: The frequency range of the high-frequency radio frequency power supply is greater than 40 MHz, and the frequency range of the low-frequency radio frequency power supply is 200 kHz to 3.2 MHz.

3. The pulsed plasma method according to claim 2, wherein: The multiple different power control periods are sequentially a first power control period, a second power control period, a third power control period and a fourth power control period; The first power control period corresponds to the period when the power of the low-frequency RF power source changes from zero to a maximum positive voltage; The second power control period corresponds to the period when the power of the low-frequency RF power source changes from a maximum positive voltage to a zero value; The third power control period corresponds to the period when the power of the low-frequency RF power source changes from zero to a maximum negative voltage; The fourth power control period corresponds to a period when the power of the low-frequency RF power source changes from a negative voltage maximum value to a zero value.

4. The pulsed plasma method according to claim 3, wherein: The duration of the first power control period and the duration of the second power control period are both less than 1 / 4 of the radio frequency cycle of the low-frequency radio frequency power supply, and the duration of the first power control period is less than the duration of the second power control period; and / or, The sum of the duration of the third power control period and the duration of the fourth power control period is greater than 1 / 2 of the RF cycle of the low-frequency RF power supply, and the duration of the third power control period is less than the duration of the fourth power control period.

5. The pulsed plasma method according to claim 3, wherein: The step of adjusting the power amplitude of the high-frequency radio frequency power supply to different power values ​​during different power control periods includes: During the first power control period, the power amplitude of the high-frequency radio frequency power supply is adjusted to a first power value; During the second power control period, the power amplitude of the high-frequency radio frequency power supply is adjusted to a second power value; During the third power control period, the power amplitude of the high-frequency radio frequency power supply is adjusted to a third power value; During the fourth power control period, the power amplitude of the high-frequency radio frequency power supply is adjusted to a fourth power value.

6. The pulsed plasma method according to claim 5, characterized in that: The first power value is equal to the initial power value of the high-frequency RF power supply, the second power value, the third power value, and the fourth power value are all less than the initial power value of the high-frequency RF power supply, and the second power value is the smallest among the second power value, the third power value, and the fourth power value.

7. The pulsed plasma method according to claim 5, wherein: The first power value and the second power value are both located in a first power value interval, the third power value and the fourth power value are both located in a second power value interval, and the first power value interval is smaller than the second power value interval.

8. The pulsed plasma method according to claim 5, wherein: The first power value and the second power value are both located in a third power value interval, the third power value and the fourth power value are both located in a fourth power value interval, and the third power value interval is greater than the fourth power value interval.

9. A semiconductor process equipment, characterized in that: The invention comprises a radio frequency device and a process chamber, wherein the process chamber has a first electrode and a second electrode placed opposite to each other, the first electrode is grounded, the radio frequency device is connected to the second electrode, and when the radio frequency device is in operation, the pulsed plasma method according to any one of claims 1 to 8 is performed.

10. The semiconductor process equipment according to claim 9, wherein: The radio frequency device includes a high-frequency radio frequency power supply, a low-frequency radio frequency power supply, a clock signal device, a pulse controller and a synchronization signal generator; The low-frequency radio frequency power supply and the high-frequency radio frequency power supply are respectively connected to the second electrode; The clock signal device is connected to the low-frequency RF power supply and the synchronization signal generator respectively, the synchronization signal generator is connected to the pulse controller, and the pulse controller is connected to the high-frequency RF power supply and the low-frequency RF power supply respectively.

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