Plasma equipment and plasma density adjustment method

Abstract

The present invention proposes a plasma device and a method for adjusting plasma density, the device comprising: a device body, a step is formed between the upper section and the lower section of the cavity, and a resonant coil is arranged on the cavity; and an adjusting unit, which is used to adjust the density of the plasma in the cavity, which is arranged outside the cavity, and comprises: an upper permanent magnet, which is arranged on an upper track and located on one side of the cavity, and the wafer film thickness corresponding to this side is lower than the wafer film thickness corresponding to other positions of the cavity; a lower permanent magnet, which is used to form magnetic lines of force with the upper permanent magnet, and the magnetic lines of force are located in the cavity, and the lower permanent magnet is arranged corresponding to the upper permanent magnet; the lower permanent magnet is placed on the lower track; the lower track is sleeved on the outside of the resonant coil and placed on the step; the upper track and the lower track are connected by a support rod. The present invention uses magnetic lines of force to adjust the plasma distribution in the cavity to be consistent, which can improve the uniformity of the wafer film.

Description

Technical Field

[0001] The invention belongs to the technical field of semiconductor manufacturing equipment, and in particular relates to a plasma device and a method for adjusting plasma density. Background Art

[0002] As integrated circuits develop towards larger scale and higher integration, in order to obtain high-quality thin film deposition, the demand for lowering the temperature of semiconductor deposition processes becomes increasingly strong, which requires the development of thin film technology that can form higher flatness at lower temperatures. Compared with traditional heating processes, the plasma-enhanced process uses an external electric field and relies on radio frequency induction to ionize the target material source gas to generate plasma, increase the activity of the reactants, and reduce the temperature required for the reaction to below 450 degrees. For example, the nitridation and oxidation process used in the DRAM process achieves selective nitridation and oxidation through plasma-enhanced processes such as ICP / CCP.

[0003] However, since the plasma in the cavity is not evenly distributed, it will be affected by factors such as the position of the molecular pumping port and the spiral shape of the resonant coil. There is limited room for improving the uniformity of the nitride and oxide films by adjusting the position of the resonant coil Coil. Summary of the invention

[0004] The purpose of the present invention is to provide a plasma device and a method for adjusting the plasma density. A permanent magnet is installed on the side of the resonant coil Coil where the plasma concentration is relatively low to form a magnetic field, and the plasma distribution in the cavity is adjusted to be uniform by using magnetic lines of force, so as to improve the uniformity of the wafer film (nitride film or oxide film). The technical solution adopted is as follows:

[0005] A plasma device comprising:

[0006] The device body has a step formed between the upper and lower sections of the cavity, and a resonant coil is arranged on the upper section of the cavity;

[0007] and an adjusting unit for adjusting the density of the plasma in the cavity, which is arranged outside the cavity and includes:

[0008] The upper permanent magnet is arranged on the upper track and is located at one side of the cavity. The wafer film thickness corresponding to the side is lower than the wafer film thickness corresponding to other positions of the cavity.

[0009] The lower permanent magnet is used to form magnetic lines of force with the upper permanent magnet, the magnetic lines of force are located in the cavity, the lower permanent magnet and the upper permanent magnet are located on the same side of the cavity and are arranged correspondingly up and down; the lower permanent magnet is arranged on the lower track;

[0010] The upper rail and the lower rail are connected via a support rod.

[0011] Preferably, the upper track comprises:

[0012] An outer ring track connected to the outer ring track of the lower track through the support rod;

[0013] An inner ring track is fixed to the outer ring track and forms an installation gap therewith;

[0014] The upper permanent magnet is located in the installation gap and is clamped between the outer ring track and the inner ring track;

[0015] The S pole of the upper permanent magnet is arranged toward the cavity; and the N pole of the upper permanent magnet is arranged away from the cavity.

[0016] Preferably, a connecting strip is welded between the inner ring track and the outer ring track, and the connecting strip extends radially.

[0017] Preferably, the upper fixing block is sleeved on the upper rail, or is threadedly connected to the upper rail.

[0018] Preferably, the number of the upper permanent magnets is ≥1; the S poles of adjacent upper permanent magnets are in contact;

[0019] One of the upper fixing blocks is located on one side of the first upper permanent magnet, and the other upper fixing block is located on one side of the last upper permanent magnet.

[0020] Preferably, the upper permanent magnet and the lower permanent magnet are both bar-shaped permanent magnets or horseshoe-shaped permanent magnets.

[0021] Preferably, the support rod is welded between the upper rail and the lower rail.

[0022] Preferably, the upper rail and the upper fixing block are both made of stainless steel.

[0023] A method for adjusting plasma density, based on the plasma device, comprises the following steps:

[0024] Step 1, assembling the adjustment unit outside the cavity;

[0025] Step 2: The equipment body is subjected to a plasma nitridation process or a plasma oxidation process to achieve uniform plasma distribution under the action of the magnetic field formed by the magnetic lines of force.

[0026] Compared with the prior art, the advantages of the present invention are:

[0027] A permanent magnet is installed on the side of the resonant coil Coil where the plasma concentration is relatively low to form a magnetic field. The plasma distribution in the cavity is adjusted to be uniform using magnetic lines of force, which can improve the uniformity of the wafer film (nitride film or oxide film). BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a structural diagram of the device body in the prior art;

[0029] Figure 2 for Figure 1 A structural diagram of an adjustment unit mounted on the device body;

[0030] Figure 3 A top view of the upper rail in the adjustment unit.

[0031] Among them, 1-wafer, 2-carrier, 3-resonance coil, 4-molecular pump port, 5-upper permanent magnet, 6-upper track, 7-upper fixed block. DETAILED DESCRIPTION

[0032] The plasma device and the method for adjusting the plasma density of the present invention will be described in more detail below in conjunction with the schematic diagram, wherein preferred embodiments of the present invention are shown, and it should be understood that those skilled in the art can modify the present invention described herein while still achieving the advantageous effects of the present invention. Therefore, the following description should be understood as being widely known to those skilled in the art and not as a limitation of the present invention.

[0033] like Figure 1 As shown, in the existing plasma equipment, the plasma in the cavity is not evenly distributed and is affected by factors such as the position of the molecular pumping port and the spiral shape of the resonant coil, so that the thickness of the film deposited on the wafer is inconsistent and the uniformity is poor. Figure 1 A transfer gate is arranged on the middle cavity.

[0034] The process chamber is a quartz chamber, including a plasma generation space and a wafer processing space.

[0035] A carrier 2 is arranged at the lower part of the cavity, and the carrier is arranged in the wafer processing space inside the process chamber. A heater is integrally embedded in the carrier to heat the wafer 1 by electricity.

[0036] A resonant RF coil 3 is provided at the upper part of the cavity, and the resonant coil is arranged to surround the outer circumference of the plasma generation chamber. A radio frequency (RF) sensor, a high frequency power supply, and a matcher capable of performing an impedance matching operation or an output frequency matching operation on the high frequency power supply are connected to the resonant coil. Not shown in the figure. The matcher is configured to adjust the impedance of the high frequency power supply or the frequency of the RF power output by the high frequency power supply according to the reflected wave information input by the RF sensor to minimize the reflected wave.

[0037] A process gas through hole is opened at the top of the cavity, and the process gas enters the cavity through the process gas through hole, and forms plasma after being excited by the radio frequency coil. A molecular pump port 4 is opened at the bottom of the cavity, and is connected to a vacuum pump to control the pressure in the cavity.

[0038] The resonant coil 3 is connected to an RF sensor, a high frequency power source, and a matching device for matching the impedance or output frequency of the high frequency power source. Figure 1 The high-frequency power supply supplies high-frequency power to the resonant coil 3, and a circular plasma ring is generated in the plasma generation area near the resonant coil 3 and along the inner periphery of the cavity. The spiral shape of the resonant coil 3 causes different heights of the plasma ring from the wafer at different positions, and the plasma is affected by the position of the molecular pumping port 4 (pumping), resulting in different diffusion speeds in different directions of the wafer.

[0039] There is limited room for improving the uniformity of nitride film and oxide film by adjusting the position of the resonant coil 3Coil and other methods.

[0040] The wafer film thickness will be thinner in areas where the plasma concentration is lower.

[0041] Therefore, in this embodiment, a permanent magnet is installed on the side of the resonant coil 3 (Coil) where the plasma concentration is relatively low to form a magnetic field, and magnetic lines of force are formed inside the cavity to bind the plasma. The magnetic lines of force are used to adjust the plasma distribution in the cavity to be consistent. The unilateral magnetron technology can significantly improve the uniformity of the nitrided oxide film.

[0042] like Figure 2~3 , a plasma device comprising:

[0043] The device body has a step formed between the upper and lower sections of the cavity, and a resonant coil 3 is arranged on the cavity.

[0044] The regulating unit is used to regulate the density of the plasma in the cavity, and is arranged outside the cavity, and comprises:

[0045] The upper permanent magnet 5 is arranged on the upper track 6 and is located at one side of the cavity. The wafer film thickness corresponding to this side is lower than the wafer film thickness corresponding to other positions of the cavity.

[0046] Among them, the film thickness measuring machine can measure the film thickness, which is a common method in the industry.

[0047] The lower permanent magnet is used to form magnetic lines of force with the upper permanent magnet 5 . The magnetic lines of force are located in the cavity. The lower permanent magnet and the upper permanent magnet 5 are arranged correspondingly up and down.

[0048] “Up and down corresponding arrangement” means that the lower permanent magnets are the same in number and are located directly below the upper permanent magnets 5 .

[0049] Therefore, an upper permanent magnet 5 and the lower permanent magnet directly below it form a magnetic field. Figure 3 As shown, a combination of several small magnets (upper permanent magnets 5), namely the adjustment unit, can be regarded as a large magnet. Therefore, the upper permanent magnet 5 only forms magnetic lines of force with the lower permanent magnet directly below it.

[0050] The lower permanent magnet is arranged on the lower track; the outer ring track of the lower track is sleeved on the outside of the resonant coil 3 and placed on the step.

[0051] The upper track 6 is connected to the lower track by a support rod. Specifically, the support rod is welded between the upper track 6 and the lower track.

[0052] like Figure 2 As shown, since the support rod is connected to the outer ring track of the upper track 6, Figure 3 The support bar in the middle is connected to the right part section of the outer ring track.

[0053] The upper permanent magnet 5 and the lower permanent magnet are installed in the same manner.

[0054] The installation method of the upper permanent magnet 5 is specifically as follows:

[0055] The upper track includes:

[0056] An outer ring track connected to the outer ring track of the lower track through a support rod;

[0057] The inner ring track is fixed to the outer ring track and forms an installation gap therewith. Specifically, a connecting strip is welded between the inner ring track and the outer ring track, and the connecting strip extends radially. The connecting strip is located outside the adjustment unit.

[0058] like Figure 3 As shown, the connection bar is not shown.

[0059] Preferably, the inner track is arranged at the upper part of the cavity where there is no resonant coil 3 .

[0060] The upper permanent magnet 5 is located in the installation gap and is clamped between the outer ring track and the inner ring.

[0061] The S pole of the upper permanent magnet 5 is arranged toward the cavity; the N pole of the upper permanent magnet is arranged away from the cavity;

[0062] The upper fixing block 7 is used to limit the upper permanent magnet 5 .

[0063] The upper fixing block 7 is sleeved on the upper rail 6 , or is threadedly connected to the upper rail 6 .

[0064] That is, the upper fixing block 7 is provided with a first hole adapted to the outer ring track and a second hole adapted to the inner ring track.

[0065] The number of upper permanent magnets 5 is ≥1; the S poles of adjacent upper permanent magnets 5 are in contact. That is, the number of permanent magnets can be increased or decreased according to the uniformity of the wafer to compensate for the plasma concentration.

[0066] One of the upper fixing blocks 7 is located on one side of the first upper permanent magnet 5 , and the other upper fixing block 7 is located on one side of the last upper permanent magnet 5 .

[0067] The upper permanent magnet 5 and the lower permanent magnet are both bar-shaped permanent magnets or horseshoe-shaped permanent magnets.

[0068] When the upper permanent magnet 5 is a horseshoe-shaped permanent magnet, the opening of the upper permanent magnet 5 is arranged upward.

[0069] When the upper permanent magnet 5 is a bar-shaped permanent magnet, the upper permanent magnet 5 is arranged horizontally.

[0070] The installation method of the lower permanent magnet is as follows:

[0071] The lower track includes:

[0072] An outer ring track connected to the outer ring track of the upper track through a support rod;

[0073] The inner ring track is fixed to the outer ring track and forms an installation gap therewith. Specifically, a connecting strip is welded between the inner ring track and the outer ring track, and the connecting strip extends in the radial direction.

[0074] Preferably, the inner track is clamped in the lower section of the cavity where there is no resonant coil 3 .

[0075] The lower permanent magnet is located in the installation gap and is clamped between the outer ring track and the inner ring.

[0076] The N pole of the lower permanent magnet is arranged toward the cavity; the S pole of the lower permanent magnet is arranged away from the cavity;

[0077] The lower fixing block is used to limit the lower permanent magnet and is located on both sides of the non-magnetic poles of the lower permanent magnet.

[0078] In this embodiment, the position of the permanent magnet can be moved according to the uniformity of the wafer to make the plasma evenly distributed, so that the plasma can be uniformly diffused toward the wafer to form a film of equal thickness, thereby improving the uniformity of the nitrided oxide film.

[0079] Therefore, in this embodiment, the upper permanent magnet 5 and the lower permanent magnet need to be configured to be movable along the corresponding tracks, and the principles are the same, and the above permanent magnet 5 is used for explanation:

[0080] When the upper permanent magnet 5 is sleeved on the upper rail 6:

[0081] The diameter of the hole 1 on the fixed block 7 is slightly larger than the outer diameter of the outer ring track of the upper track 6; the diameter of the hole 2 on the upper permanent magnet 5 is slightly larger than the outer diameter of the inner ring track of the upper track 6, so that the fixed block 7 can be installed at any position on the circumference.

[0082] When the upper permanent magnet 5 is threadedly connected to the upper rail 6:

[0083] An outer thread is formed on the inner and outer rings of the upper rail 6 , respectively, so that the fixing block 7 can be installed at any position on the circumference.

[0084] Furthermore, the materials of the upper rail 6, the upper fixing block 7, the lower rail and the lower fixing block are all made of stainless steel or other materials.

[0085] The method for adjusting plasma density comprises the following steps:

[0086] Step 1, assembling the adjustment unit outside the cavity;

[0087] Step 2: The equipment body is subjected to a plasma nitridation process or a plasma oxidation process to achieve uniform plasma distribution under the action of the magnetic field formed by the magnetic lines of force.

[0088] The uniformity of the film thickness is used to inversely characterize the uniformity of the plasma distribution: Figure 1 The morphology of the wafers is not equal to the thickness, Figure 2 Medium crystal morphology and equal thickness.

[0089] The above is only a preferred embodiment of the present invention and does not limit the present invention in any way. Any technician in the relevant technical field, without departing from the scope of the technical solution of the present invention, makes any form of equivalent replacement or modification to the technical solution and technical content disclosed in the present invention, which does not depart from the content of the technical solution of the present invention and still falls within the protection scope of the present invention.

Claims

1. A plasma device, characterized in that: include: The device body has a step formed between the upper and lower sections of the cavity, and a resonant coil is arranged on the upper section of the cavity; and an adjusting unit for adjusting the density of the plasma in the cavity, which is arranged outside the cavity and includes: The upper permanent magnet is arranged on the upper track and is located at one side of the cavity. The wafer film thickness corresponding to the side is lower than the wafer film thickness corresponding to other positions of the cavity. The lower permanent magnet is used to form magnetic lines of force with the upper permanent magnet, the magnetic lines of force are located in the cavity, the lower permanent magnet and the upper permanent magnet are located on the same side of the cavity and are arranged correspondingly up and down; the lower permanent magnet is arranged on the lower track; The upper rail and the lower rail are connected via a support rod.

2. The plasma device according to claim 1, characterized in that: The upper track comprises: An outer ring track connected to the outer ring track of the lower track through the support rod; An inner ring track is fixed to the outer ring track and forms an installation gap therewith; The upper permanent magnet is located in the installation gap and is clamped between the outer ring track and the inner ring track; The S pole of the upper permanent magnet is arranged toward the cavity; and the N pole of the upper permanent magnet is arranged away from the cavity.

3. The plasma device according to claim 2, characterized in that: A connecting strip is welded between the inner ring track and the outer ring track, and the connecting strip extends in the radial direction.

4. The plasma device according to claim 2, characterized in that: The number of the upper permanent magnets is ≥1; the S poles of adjacent upper permanent magnets are in contact; One of the upper fixing blocks is located on one side of the first upper permanent magnet, and the other upper fixing block is located on one side of the last upper permanent magnet.

5. The plasma device according to claim 4, characterized in that: The upper fixing block is sleeved on the upper rail, or is threadedly connected to the upper rail.

6. The plasma device according to claim 1, characterized in that The upper permanent magnet and the lower permanent magnet are both bar-shaped permanent magnets or horseshoe-shaped permanent magnets.

7. The plasma device according to claim 1, characterized in that: The support rod is welded between the upper rail and the lower rail.

8. The plasma device according to claim 1, characterized in that The upper rail and the upper fixing block are made of stainless steel.

9. A method for adjusting plasma density, based on the plasma device according to any one of claims 1 to 8, characterized in that: The following steps are involved: Step 1, assembling the adjustment unit outside the cavity; Step 2: The equipment body is subjected to a plasma nitridation process or a plasma oxidation process to achieve uniform plasma distribution under the action of the magnetic field formed by the magnetic lines of force.

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