Plasma processing apparatus and control method thereof

Abstract

The application discloses a kind of plasma processing equipment and its control method, and the plasma processing equipment includes reaction cavity, and the shower head in the upper portion of reaction cavity, the shower head is used to provide process gas, and the pedestal is provided below the shower head, and the wafer is carried on the pedestal, and the lower electrode RF source is connected to the pedestal, and the first RF is provided to excite plasma in the space between the shower head and wafer, and the moving ring is provided radially outside the shower head, and the restraint ring is provided radially outside the pedestal, and the moving ring is driven to lift by lifting device, to fall in the process, and the moving ring is cooperated with restraint ring to jointly constrain plasma area, and it further includes moving ring RF assembly, and the moving ring RF assembly includes moving ring RF source, and the electrode on the moving ring is electrically connected by first link to moving ring RF source, to feed into second RF to moving ring, and the frequency of second RF is same with first RF, and the phase is same, to limit plasma area.

Description

Technical Field

[0001] This application relates to the field of semiconductor processing technology, and in particular to a plasma processing apparatus and its control method. Background Technology

[0002] In semiconductor processing equipment, as processing precision increases, the process time for a single etching / deposition is shortened, and there are repeated alternations, requiring rapid gas switching and placing higher demands on exhaust efficiency.

[0003] One way to improve exhaust efficiency is to increase the radial volume of the reaction chamber, thereby providing more exhaust space, reducing flow resistance, and improving exhaust efficiency. However, such a setup will result in an increase in the equivalent upper electrode area, an increase in the plasma region volume, and a decrease in plasma density. As a result, it is necessary to significantly increase the RF power, which poses a challenge to RF devices and significantly increases energy consumption. Furthermore, the expansion of the plasma region will lead to a decrease in its edge stability, posing a challenge to process stability and consistency. Summary of the Invention

[0004] The present invention aims to solve one of the technical problems existing in the prior art, and proposes a plasma processing device and its control method.

[0005] According to one aspect of the present invention, a plasma processing apparatus is provided, comprising a reaction chamber and a spray head located above the reaction chamber, the spray head being used to provide process gas, a base being disposed below the spray head, a wafer being supported on the base, and a lower electrode radio frequency source being connected to the base, the lower electrode radio frequency source providing a first radio frequency to excite plasma in the space between the spray head and the wafer, a moving ring being provided radially outward of the spray head, and a constraint ring being provided radially outward of the base, the moving ring being driven to rise and fall by a lifting device to drop the moving ring during the process, cooperating with the constraint ring to constrain the plasma region, and further comprising a moving ring radio frequency assembly, the moving ring radio frequency assembly including a moving ring radio frequency source, the moving ring radio frequency source being electrically connected to an electrode on the moving ring via a first link to feed a second radio frequency to the moving ring, the second radio frequency having the same frequency and phase as the first radio frequency, to confine the plasma region.

[0006] Optionally, the movable ring has a slot inside to accommodate the electrode.

[0007] Optionally, the electrode is disposed on the inner side of the movable ring opposite to the space.

[0008] Optionally, the movable ring is made of an insulating material.

[0009] Optionally, the mobile ring radio frequency source is electrically connected to the constraint ring via a second link to feed a third radio frequency into the constraint ring.

[0010] Optionally, the third radio frequency has the same frequency and phase as the first radio frequency to confine the plasma region.

[0011] Optionally, it also includes a synchronization controller, which is electrically connected to the moving ring radio frequency source and the lower electrode radio frequency source, and synchronizes the frequency of the second radio frequency with the frequency of the first radio frequency in real time, and makes the phase of the second radio frequency the same as the phase of the first radio frequency.

[0012] Optionally, it further includes a synchronization controller electrically connected to the moving ring radio frequency source and the lower electrode radio frequency source, which synchronizes the frequencies of the second radio frequency and the third radio frequency with the frequency of the first radio frequency in real time, and makes the phases of the second radio frequency and the third radio frequency the same as the phase of the first radio frequency.

[0013] Optionally, a plasma state monitoring device is also provided to monitor the plasma state of the area where the moving ring is located.

[0014] Optionally, the plasma state monitoring device includes a plasma luminescence monitoring system, an electrostatic probe, or a magnetic probe.

[0015] Optionally, a plasma state monitoring device is also provided to monitor the plasma state of the area where the moving ring is located. The synchronization controller controls the radio frequency power of the moving ring radio frequency source based on the signal of the first radio frequency and the monitoring signal of the plasma state monitoring device, so as to regulate the plasma state of the area where the moving ring is located.

[0016] Optionally, the first link and / or the second link have on / off switches.

[0017] According to another aspect of the present invention, a control method based on the plasma processing device as described above is proposed, wherein when the plasma in the region where the moving ring is located is in an excited state, a second radio frequency is fed into the moving ring, the second radio frequency having the same frequency and phase as the first radio frequency fed into the lower electrode, so as to extinguish the plasma in the region where the moving ring is located.

[0018] Optionally, when the plasma in the region where the moving ring is located is in an extinguished state and it is necessary to further restrict the plasma region in the space, a second radio frequency is fed to the electrode and a third radio frequency is fed to the constraint ring. The second radio frequency and the third radio frequency have the same frequency and phase as the first radio frequency to further restrict the plasma region.

[0019] Optionally, the power of the first radio frequency can be increased to further confine the plasma region within the space.

[0020] The present invention extinguishes the plasma in the region where the moving ring is located by feeding a second radio frequency into the moving ring, wherein the second radio frequency has the same frequency and phase as the first radio frequency fed into the lower electrode, thereby limiting the plasma region. Attached Figure Description

[0021] To more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are merely exemplary, and those skilled in the art can derive other embodiments based on the provided drawings without creative effort.

[0022] The structures, proportions, sizes, etc. illustrated in this specification are only for the purpose of assisting those skilled in the art in understanding and reading the content disclosed herein, and are not intended to limit the conditions under which the present invention can be implemented. Therefore, they have no substantial technical significance. Any modifications to the structure, changes in the proportions, or adjustments to the size, without affecting the effects and objectives that the present invention can produce, should still fall within the scope of the technical content disclosed in the present invention.

[0023] Figures 1 to 4 These are schematic diagrams illustrating different embodiments of a plasma processing device according to the present invention;

[0024] Figure 5 This is an example diagram of a radio frequency waveform on a moving ring (MR) according to the present invention;

[0025] Figure 6 , Figure 7 This is a diagram illustrating the difference in effects. Detailed Implementation

[0026] The following specific embodiments illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0027] This invention provides a plasma processing device, such as... Figure 1As shown, the system includes a spray head 30 located at the top of the reaction chamber, which provides process gas. Below the spray head 30 is a base 70, on which a wafer W is supported. The base 70 is connected to a lower electrode (LE) radio frequency (RF) source 60, which provides high-frequency (HF) radio frequency to excite plasma in the space 40 between the spray head 30 and the wafer W.

[0028] The spray head 30 is provided with a moving ring (MR) 10 on the radial outer side, and the base 70 is provided with a constraint ring 20 on the radial outer side.

[0029] The moving ring 10 is driven to rise and fall by the lifting device 11. During the process, the moving ring 10 falls and cooperates with the constraint ring 20 to jointly constrain the plasma region 41, as shown below. Figure 6 As shown, the plasma is extinguished near the moving ring 10 and the constraint ring 20 to stabilize the plasma edge region.

[0030] Optionally, a focusing ring 50 is provided on the radially outer side of the wafer W, and the focusing ring 50 is supported by the base 70 to improve the wafer edge etching yield.

[0031] The confinement ring 20, as a component separating the plasma region and the exhaust region, significantly affects the exhaust efficiency due to its flow conduction. As described in the background art, one way to improve exhaust efficiency is to increase the radial volume of the reaction chamber while keeping the base 70 unchanged. This results in a larger radial area for the confinement ring 20, allowing for more flow paths under the same plasma confinement force, thus leading to higher overall exhaust efficiency. However, this would cause various problems mentioned in the background art.

[0032] To address at least one of the aforementioned problems, the plasma processing apparatus proposed in this invention further includes a moving ring radio frequency (RF) assembly. The moving ring RF assembly includes a moving ring RF source 110, which is electrically connected to electrodes 120 on the moving ring 10 via a first link 111 to feed RF signals into the moving ring 10. Furthermore, when further confinement of the plasma is required, i.e., limiting / reducing the plasma region, such as... Figure 5 As shown, the radio frequency (MR-HF) fed by the moving ring radio frequency source 110 and the radio frequency (LE-HF) fed by the lower electrode radio frequency source 60 have the same frequency and phase. Therefore, the plasma around the moving ring 10 has its potential reduced to zero due to the cancellation of the radio frequency (LE-HF) fed by the lower electrode radio frequency source 60 by the radio frequency of the same frequency and direction. Furthermore, the moving ring 10 is close to the circumference of the spray head 30, making it difficult to generate plasma between them, thus extinguishing the plasma around the moving ring 10. Figure 7As shown, this concentrates the edge of plasma region 42 more towards the central region, increasing plasma density and stabilizing the plasma edge region, thus improving the edge etching morphology of wafer W. Furthermore, it reduces the high power requirement of the lower electrode RF source 60. Since the RF (MR-HF) power fed by the moving ring RF source 110 is only used to offset the plasma energy around the moving ring 10, and the plasma energy around the moving ring 10 is lower than that in the plasma center region, the above objective can be achieved with a power much smaller than that fed by the lower electrode RF source 60. Consequently, overall, power consumption is reduced, lowering energy loss. This reduction not only helps lower equipment operating costs but also reduces carbon emissions and other pollutant emissions that may occur during energy production, which is beneficial for environmental protection.

[0033] In one embodiment, the moving ring 10 may be a hollow structure or have internal slots to accommodate the electrode 120, thereby preventing the electrode 120 from being bombarded and eroded as it is in direct contact with the plasma.

[0034] Preferably, the electrode 120 is disposed on the inner side of the side of the moving ring 10 opposite to the space 40. That is, the electrode 120 is located inside the side of the moving ring 10 opposite to the space 40, thereby minimizing the energy loss and phase error of the radio frequency (MR-HF) fed into the moving ring radio frequency source 110.

[0035] In one embodiment, the moving ring 10 is made of insulating material to prevent radio frequency energy from being conducted to the lifting device 11 via the moving ring 10.

[0036] In one embodiment, such as Figure 2 As shown, the moving ring RF source 110 is electrically connected to the confinement ring 20 via the second link 112 to feed RF into the confinement ring 20. This RF has the same frequency and phase as the LE-HF RF fed by the lower electrode RF source 60. Therefore, it can not only suppress and extinguish the plasma around the moving ring 10, but also simultaneously suppress and extinguish the plasma around the confinement ring 20, thereby further strengthening the confinement capability of the plasma, making it more concentrated in the central region, increasing the plasma density, or reducing the power requirement of the LE-HF RF fed by the lower electrode RF source 60.

[0037] Preferably, the radio frequency power fed into the confinement ring 20 is much smaller than the radio frequency power fed into the lower electrode radio frequency source 60, so as to prevent plasma from being generated between the confinement ring 20 and the spray head 30.

[0038] In one embodiment, such as Figure 3 , 4As shown, it also includes a synchronization controller 200, which is electrically connected to the moving ring RF source 110 and the lower electrode RF source 60. The synchronization controller 200 synchronizes the RF frequency of the moving ring RF source 110 with the RF frequency of the lower electrode RF source 60 in real time, and makes the RF phase of the moving ring RF source 110 the same as the RF phase of the lower electrode RF source 60, thereby improving the accuracy of the output RF of the moving ring RF source 110 and enabling it to quickly respond to RF changes of the lower electrode RF source 60.

[0039] In one embodiment, a plasma state monitoring device is also provided to monitor the plasma state of the area where the moving ring 10 is located.

[0040] Optionally, the plasma state monitoring device includes a plasma luminescence monitoring system, which determines the discharge state by monitoring the plasma luminescence intensity. The plasma state monitoring device includes a photodiode and an optical fiber, which convert the plasma luminescence signal of the region where the moving ring 10 is located into an electrical signal, thereby enabling real-time monitoring of the plasma excitation, maintenance, and extinction processes. When the plasma in the region where the moving ring 10 is located is extinguished, the luminescence intensity will significantly decrease or disappear.

[0041] Optionally, the plasma state monitoring device includes an electrostatic probe to measure parameters such as electron density, temperature, and potential of the plasma in the region where the moving ring 10 is located. When the plasma in the region where the moving ring 10 is located is extinguished, the electron density drops sharply, and the probe current also decreases accordingly.

[0042] Optionally, the plasma state monitoring device includes a magnetic probe, which measures the changes in the magnetic field in the plasma in the region where the moving ring 10 is located. When the plasma is extinguished, the magnetic field strength will decrease significantly, and by monitoring the changes in the magnetic field, it can be determined whether the plasma in the region where the moving ring 10 is located has been extinguished.

[0043] Furthermore, the synchronization controller 200 controls the radio frequency power of the moving ring radio frequency source 110 based on the radio frequency signal output by the lower electrode radio frequency source 60 and the monitoring signal of the plasma state monitoring device, so as to regulate the plasma state of the region where the moving ring 10 is located.

[0044] In one embodiment, the first link 111 and / or the second link 112 have on / off switches. Because when the first link 111 and / or the second link 112 is in the on state, it changes the radio frequency circuit within the reaction cavity, when the plasma region is in... Figure 6When the plasma region 41 is in a specific state, a portion of the RF circuit will be connected to the moving ring RF source 110 via the first link 111 and / or the second link 112, which is detrimental to electrical safety and RF circuit consistency. Therefore, when it is not necessary to confine the plasma region, the first link 111 and / or the second link 112 should be disconnected to avoid the aforementioned problems.

[0045] When it is necessary to confine the plasma region within space 40, that is, to make the plasma region more concentrated near wafer W, the plasma state of the region where the moving ring 10 is located is first determined based on the monitoring signal of the plasma state monitoring device.

[0046] When the plasma in the region where the moving ring 10 is located is detected to be in an excited state, the moving ring radio frequency source 110 is controlled to be electrically connected to the electrode 120 through the first link 111, and the radio frequency (MR-HF) fed in is the same frequency and phase as the radio frequency (LE-HF) fed in by the lower electrode radio frequency source 60, so as to extinguish the plasma in the region where the moving ring 10 is located.

[0047] In some embodiments, when the plasma in the region where the moving ring 10 is located is detected to be extinguished, the radio frequency power of the moving ring radio frequency source 110 is no longer increased in order to maintain the stability of the radio frequency circuit and save energy.

[0048] When the plasma in the region where the moving ring 10 is located is detected to be extinguished, and the plasma region within space 40 needs to be further confined, the control moving ring radio frequency source 110 is electrically connected to the electrode 120 via the first link 111 and to the moving ring 10 via the second link 112. The radio frequency (MR-HF) fed into it has the same frequency and phase as the radio frequency (LE-HF) fed into the lower electrode radio frequency source 60. Thus, the joint constraint ring 20 and the moving ring 10 jointly apply a radio frequency with the same frequency and phase as the radio frequency (LE-HF) fed into the lower electrode radio frequency source 60 to further confine the plasma region.

[0049] In some embodiments, the plasma region can be further confined by increasing the radio frequency power of the mobile ring radio frequency source 110.

[0050] Since the plasma around the moving ring 10 has its potential reduced to zero due to the cancellation of the radio frequency (LE-HF) fed by the lower electrode radio frequency source 60 with the radio frequency of the same frequency and direction, an equivalent radio frequency circuit break is formed. Therefore, the plasma in this region cannot be excited because there is no high-frequency alternating electric field. Furthermore, the formation of an equivalent radio frequency circuit break also avoids problems such as radio frequency circuit instability and reduced consistency.

[0051] Although the present invention has been described in detail above with general descriptions and specific embodiments, modifications or improvements can be made to it, which will be obvious to those skilled in the art. Therefore, all such modifications or improvements made without departing from the spirit of the present invention fall within the scope of protection claimed by the present invention.

Claims

1. A plasma processing device, comprising: A reaction chamber, and a spray head located above the reaction chamber, the spray head being used to supply process gases. A base is provided below the spray head, and the wafer is supported on the base. The base is connected to a lower electrode radio frequency source, which provides a first radio frequency to excite plasma in the space between the spray head and the wafer. The spray head has a movable ring on its radially outer side, and the base has a constraint ring on its radially outer side. The movable ring is driven to rise and fall by a lifting device so that during the process, the movable ring falls down and cooperates with the constraint ring to confine the plasma region. Its features are, Also includes The mobile ring radio frequency assembly includes a mobile ring radio frequency source. The mobile ring radio frequency source is electrically connected to the electrodes on the mobile ring via a first link to feed the second radio frequency into the mobile ring. The second radio frequency has the same frequency and phase as the first radio frequency to confine the plasma region.

2. The plasma processing equipment as described in claim 1, characterized in that, The movable ring has a slot inside to accommodate the electrode.

3. The plasma processing equipment as described in claim 2, characterized in that, The electrode is located on the inner side of the side of the moving ring opposite to the space.

4. The plasma processing apparatus as described in claim 1, characterized in that, The moving ring is made of insulating material.

5. The plasma processing apparatus as described in claim 1, characterized in that, The mobile ring radio frequency source is electrically connected to the constraint ring via a second link to feed the constraint ring with a third radio frequency.

6. The plasma processing apparatus as described in claim 5, characterized in that, The third radio frequency has the same frequency and phase as the first radio frequency, in order to confine the plasma region.

7. The plasma processing apparatus as described in claim 1, characterized in that, It also includes a synchronization controller, which is electrically connected to the moving ring radio frequency source and the lower electrode radio frequency source, and synchronizes the frequency of the second radio frequency with the frequency of the first radio frequency in real time, and makes the phase of the second radio frequency the same as the phase of the first radio frequency.

8. The plasma processing apparatus as described in claim 6, characterized in that, It also includes a synchronization controller, which is electrically connected to the moving ring radio frequency source and the lower electrode radio frequency source, and synchronizes the frequencies of the second radio frequency and the third radio frequency with the frequency of the first radio frequency in real time, and makes the phases of the second radio frequency and the third radio frequency the same as the phases of the first radio frequency.

9. The plasma processing apparatus as described in claim 1, characterized in that, It is also equipped with a plasma state monitoring device to monitor the plasma state of the area where the moving ring is located.

10. The plasma processing apparatus as described in claim 9, characterized in that, The plasma state monitoring device includes a plasma luminescence monitoring system, an electrostatic probe, or a magnetic probe.

11. The plasma processing apparatus as described in claim 7 or 8, characterized in that, A plasma state monitoring device is also provided to monitor the plasma state of the area where the moving ring is located. The synchronization controller controls the radio frequency power of the moving ring radio frequency source based on the signal of the first radio frequency and the monitoring signal of the plasma state monitoring device, so as to regulate the plasma state of the area where the moving ring is located.

12. The plasma processing apparatus as described in claim 1 or 5, characterized in that, The first link and / or the second link have on / off switches.

13. A control method based on the plasma processing equipment as described in any one of claims 1-12, characterized in that, When the plasma in the region where the moving ring is located is in an excited state, a second radio frequency is fed to the electrode. The second radio frequency has the same frequency and phase as the first radio frequency, so as to extinguish the plasma in the region where the moving ring is located.

14. The control method as described in claim 13, characterized in that, When the plasma in the region where the moving ring is located is in an extinguished state, and it is necessary to further restrict the plasma region in the space, a second radio frequency is fed into the electrode, and a third radio frequency is fed into the constraint ring. The second radio frequency and the third radio frequency have the same frequency and phase as the first radio frequency, so as to further restrict the plasma region.

15. The control method as described in claim 13 or 14, characterized in that, Increase the power of the first radio frequency to further confine the plasma region within the space.

Images