Radio frequency adjustment device, plasma processing equipment and radio frequency electric field adjustment method

Abstract

The present invention provides a radio frequency adjustment device, a plasma processing device and a radio frequency electric field adjustment method, comprising a baffle located between a reaction chamber and an inner liner of the plasma processing device, and a driving component for controlling the movement of the baffle, wherein the capacitance of a radio frequency circuit inside the plasma processing device is adjusted by changing the position of the baffle, thereby adjusting the uniformity of the radio frequency electric field, effectively compensating for the uneven radio frequency electric field caused by opening a film transmission port on the side wall of the reaction chamber or the asymmetry of components inside the reaction chamber, making the formed plasma more uniform and stable, and providing a guarantee for the processing yield of the substrate surface.

Description

Technical Field

[0001] The present invention relates to the technical field of plasma etching, and in particular to a radio frequency modulation device, plasma processing equipment using the device, and a method for regulating a radio frequency electric field. Background Art

[0002] Micromachining of semiconductor substrates or substrates is a well-known technology that can be used to manufacture, for example, semiconductors, flat panel displays, light emitting diodes (LEDs), solar cells, etc. An important step in micromachining manufacturing is a plasma treatment process step, which is performed inside a reaction chamber, and a process gas is input into the reaction chamber. A radio frequency source is inductively and / or capacitively coupled to the reaction chamber to form a radio frequency electric field to excite the process gas, so as to generate and maintain plasma, and the substrate is etched by the plasma.

[0003] The density of plasma affects the efficiency of etching, while the distribution of RF electric field affects the density of plasma. Generally speaking, one factor that affects the RF electric field inside the reaction chamber is the morphology inside the reaction chamber. In order to achieve a uniform RF electric field as much as possible, the reaction chamber and the components inside are usually designed into a symmetrical structure, that is, a common cylindrical or toroidal shape.

[0004] However, in the prior art, the reaction chamber and its internal components are not all designed to be symmetrical structures around the center. Depending on different situations, some asymmetric components will affect the uniform distribution of the RF electric field, thereby resulting in different etching rates and reducing the yield rate of semiconductor processing. Summary of the invention

[0005] In order to solve the above technical problems, the present invention provides a radio frequency adjustment device, which is located between the inner wall and the inner liner of the reaction chamber of the plasma processing equipment and is used to adjust the distribution of the radio frequency electric field, including:

[0006] a baffle located between the inner wall and the inner liner of the reaction chamber and not in contact with the inner wall and the inner liner;

[0007] A driving assembly is located in the reaction chamber, wherein the driving assembly is fixedly connected to the baffle plate and is used for moving the baffle plate along the inner wall of the reaction chamber.

[0008] Optionally, the baffle is annular and is divided into at least two arc-shaped plates in the circumferential direction of the ring, and the driving assembly can control the arc-shaped plates to move separately.

[0009] Optionally, at least two of the arc-shaped plates have different heights.

[0010] Optionally, the baffle is made of semiconductor.

[0011] Optionally, the baffle is made of metal.

[0012] Optionally, the baffle is made of aluminum and has a surface plated with nickel.

[0013] Optionally, the driving assembly may also control the baffle to move in a circumferential direction and / or move up and down along the inner wall of the reaction chamber.

[0014] Optionally, the drive assembly may record position data of the baffle.

[0015] Furthermore, the present invention also provides a plasma processing device, including a reaction chamber and a liner located in the reaction chamber, and also including any one of the above-mentioned radio frequency adjustment devices.

[0016] Optionally, the reaction chamber has a film transmission port, and the baffle can at least partially cover the film transmission port by moving.

[0017] Furthermore, the present invention also provides a method for adjusting a radio frequency electric field, comprising the following steps:

[0018] Initializing the position of a baffle in any of the above-mentioned radio frequency adjustment devices;

[0019] introducing a reactive gas into a plasma processing device;

[0020] Applying a radio frequency electric field to excite plasma to etch the substrate in the reaction chamber;

[0021] The baffle is adjusted according to the uniformity of the surface of the etched substrate.

[0022] Optionally, when adjusting the position of the baffle, the drive assembly may record the position data of the baffle for forming a visual image in an external operating system.

[0023] Optionally, the following steps are also included:

[0024] For a location on the surface of the substrate where the etching depth is relatively shallow after etching, the baffle closest to the location is raised;

[0025] For locations on the substrate surface where the etching depth is deeper after etching, the baffle closest to the location is lowered.

[0026] The advantages of the present invention are as follows: the present invention provides a radio frequency adjustment device, which can adjust the capacitance of the radio frequency circuit inside the plasma processing equipment to adjust the uniformity of the radio frequency electric field, effectively compensate for the uneven radio frequency electric field caused by opening a film transfer port on the side wall of the reaction chamber or the asymmetry of the components inside the reaction chamber, make the formed plasma more uniform and stable, and provide a guarantee for the processing yield of the substrate surface. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0028] Figure 1 A schematic structural diagram of a plasma processing device is shown;

[0029] Figure 2 A partial top view of a plasma processing device is shown;

[0030] Figure 3 A schematic diagram of the baffle structure of a radio frequency adjustment device according to an embodiment is shown. DETAILED DESCRIPTION

[0031] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0032] Figure 1 A schematic diagram of the structure of a plasma processing device is shown, which includes a vacuum-evacuable reaction chamber 110 surrounded by metal materials. The reaction chamber 110 is used to process substrates. The reaction chamber 110 includes an electrostatic chuck 140 inside, which is used to support the substrate while controlling the substrate temperature, electric field and other factors that affect the substrate processing. The electrostatic chuck 140 is provided with a temperature control device to control the temperature of the upper substrate. A DC electrode is also provided inside the electrostatic chuck 140, through which DC adsorption is generated between the back of the substrate and the bearing surface of the electrostatic chuck 140 to fix the substrate. A plasma confinement ring 170 is arranged around the electrostatic chuck 140, located between the electrostatic chuck 140 and the side wall of the reaction chamber 110, and is used to confine the plasma to the reaction area while allowing gas to pass through; a grounding ring is provided below the plasma confinement ring to provide electric field shielding to prevent plasma leakage. A gas nozzle 160 is provided at the top of the reaction chamber 110 for introducing reaction gas, and a radio frequency power supply is generally used to apply a radio frequency signal to the electrostatic chuck 140 or the gas nozzle 160. The radio frequency signal forms a radio frequency electric field in the reaction chamber 110 for exciting plasma. In some embodiments, a bias radio frequency power supply is also provided to couple to the electrostatic chuck 140 to control the bombardment direction of the plasma. The radio frequency adjustment device disclosed in the present invention can be used for example Figure 1 The plasma processing equipment shown.

[0033] like Figure 1 As shown, when the plasma is in the etching process, it will cause a certain amount of corrosion to the side wall of the reaction chamber 110. A small amount of corrosion will cause the side wall to produce particulate contaminants that can fall off, destroy the etching uniformity of the substrate surface, and affect the performance of the integrated circuit. Severe corrosion will shorten the service life of the reaction chamber. In order to avoid this situation, a liner 120 is set between the generated plasma and the side wall of the reaction chamber 110. The metal material is also used. In some embodiments, aluminum, the same material as the side wall of the reaction chamber, can be selected, and a corrosion-resistant coating can be evaporated on it. The liner 120 overlaps the upper edge of the side wall of the reaction chamber. Except for the upper edge contact, the other areas usually maintain a certain gap between the two. Therefore, according to the skin principle, when the radio frequency signal flows through the side wall of the reaction chamber 110, it will also pass along the surface of the liner 120, and the liner 120 will be incorporated into the radio frequency circuit. If the plasma bombards the liner 120 for a long time and causes it to be damaged, the liner 120 is easier to replace than the side wall of the reaction chamber. However, although different components are designed and manufactured into symmetrical structures as much as possible, such as the annular inner liner 120, in order to maintain the uniform distribution of the radio frequency electric field in the space inside the reaction chamber, there are still cases where the internal devices destroy the symmetry. For example, in order to transfer the substrate in and out, a film transfer port 111 is provided on the reaction chamber 110 and / or the inner liner 120. Compared with other positions, the film transfer port 111 will cause the radio frequency signal propagating along the surface to be vacant here, thereby affecting the morphology of the plasma near it, causing a deviation in the etching rate of the substrate.

[0034] In one embodiment of the present invention, a baffle 130 is provided between the reaction chamber 110 and the liner 120 so as not to contact the two. The material of the baffle 130 may be a metal material or a semiconductor material. In some embodiments, the material of the baffle is aluminum with nickel plated on the surface. The capacitance of the RF circuit is calculated according to the formula:

[0035] C = εS / d;

[0036] The liner 120 and the side wall of the reaction chamber are regarded as a flat plate capacitor, wherein the relative area between the two is S, the distance between the two is d, and the dielectric constant of the baffle 130 is regarded as ε.

[0037] The baffle 130 can move along the side wall through the driving assembly 131. In some embodiments, the baffle 130 can move up and down to at least partially cover the film transmission port 111 on the side wall of the reaction chamber. Because the existence of the film transmission port 111 makes the S value here smaller, and by covering this place with the baffle 130, the overall reduced capacitance value can be compensated by increasing ε, thereby achieving the effect of adjusting the RF electric field.

[0038] like Figure 3 As shown, in some embodiments, the baffle 130 can be a concave plate with a middle notch, and the notch corresponds to the film transmission port 111. It is suitable for the situation that the baffle 130 is relatively high and still blocks the film transmission port 111 even when it drops to the lowest point. When film transmission is required, the baffle 130 drops and does not block the film transmission channel. When adjustment is required, the baffle 130 rises. The concave plate can further increase the effective area between the side wall of the inserted reaction chamber 110 and the liner 120, thereby achieving a greater adjustment effect. Correspondingly, corresponding shape compensation can be set at the opposite side of the concave shape of the baffle 130 to achieve overall symmetry of the RF electric field. In other embodiments, the driving assembly 131 can control the baffle 130 to rotate in a circular direction. The baffle 130 is a curved plate with the same curvature as the side wall of the reaction chamber 110. When film transmission is required, the baffle 130 is rotated away from the film transmission port 111 and does not block the film transmission channel. When adjustment is required, the baffle 130 rotates back to the film transmission port 111 to adjust the overlapping area therewith to adjust the RF electric field here to balance with other positions in the reaction chamber.

[0039] like Figure 2 As shown, it is another embodiment of the present invention, the baffle 130 is an annular plate, which is divided into four parts along the circumferential direction, and the up and down movements can be controlled separately by the driving component 131, and the whole baffle 130 can be controlled to rotate along the circumference by the driving component 131. In other embodiments, the baffle can be divided into other numbers of sub-arc plates according to actual conditions, such as two or five pieces, and the size of each arc plate is not necessarily the same, and can be different in size in the circumferential direction or in the upper and lower heights. In this way, when adjusting the RF electric field, there can be a more flexible control method. For example, in addition to changing the position of the baffle 130 according to the film transmission port 111 on the side wall of the reaction chamber 110, the position of the baffle 130 can also be changed according to other asymmetric components inside the reaction chamber 110, so as to achieve the purpose of comprehensive adjustment.

[0040] In other embodiments, the driving component 131 can record the position data of the baffle 130. For example, starting from the initial position, the position change of each subsequent movement, including the rotation or raising and lowering of the baffle 130, will be transmitted to the human-computer interaction device outside the reaction chamber through the communication module, and a visual graphical interface will be formed on the display screen of the device to display the changes of the baffle 130 inside the current reaction chamber 110 in real time. This is more conducive to preliminarily analyzing the next movement plan of the baffle 130 in combination with the physical morphology inside the reaction chamber.

[0041] Optionally, the present invention further provides a plasma processing device, which may be an inductively coupled plasma processing device or a capacitively coupled plasma processing device, and may not be limited to the above two plasma processing devices, and the processing device includes a metal reaction chamber 110, a metal liner 120, and any one of the above radio frequency adjustment devices located between the side wall of the reaction chamber and the liner 120. The purpose of adjusting the radio frequency electric field is achieved by controlling the movement of the baffle 130 through the driving component 131 to adjust the capacitance in the radio frequency loop, and a uniform and symmetrical radio frequency electric field can make the plasma etching more uniform.

[0042] Optionally, the present invention further provides a method for adjusting a radio frequency electric field, comprising the following steps:

[0043] Initialize the position of the baffle 130 in any of the above-mentioned RF adjustment devices. According to the analysis of the actual situation, the baffle 130 can be moved to a certain position, such as first moving it to the vicinity of the film transmission port 111 and partially blocking the film transmission port 111, and applying a radio frequency electric field to excite it into plasma after the reaction gas is introduced, and the surface of the sample substrate is etched. The distribution of the radio frequency electric field in the reaction chamber is indirectly analyzed by analyzing the morphology of the substrate surface after the etching is completed. According to the analysis results, the baffle is adjusted again and the reaction process is repeated until the etching result meets the requirements, and the position of the baffle at this time is recorded as a common configuration for subsequent reactions. In some embodiments, the specific analysis process includes, for a position where the etching depth of the substrate surface is shallow after etching, raising the baffle closest to the position in the reaction chamber to increase the capacitance there, and improve the reaction rate there, and for a position where the etching depth of the substrate surface is deep after etching, lowering the baffle closest to the position there, and reducing the capacitance there, and reducing the reaction rate there. In some embodiments, the movement of the baffle is operated through a visual image operation interface. During each analysis, in addition to referring to the etching status of the sample substrate, the positional relationship between the baffle and other components in the reaction chamber can be analyzed based on the baffle position data returned by the driving component, and the next adjustment of the baffle position can be determined based on the data. In this way, the number of times the most suitable position is found can be reduced, and the adjustment efficiency can be improved.

[0044] Although the content of the present invention has been described in detail through the above preferred embodiments, it should be appreciated that the above description should not be considered as a limitation of the present invention. After reading the above content, it will be apparent to those skilled in the art that various modifications and substitutions of the present invention will occur. Therefore, the protection scope of the present invention should be limited by the appended claims.

Claims

1. A radio frequency adjustment device, located between the inner wall and the inner lining of a reaction chamber of a plasma processing device, for adjusting the distribution of a radio frequency electric field, wherein the inner lining is made of metal, and is characterized in that: include: a baffle located between the inner wall and the inner liner of the reaction chamber and not in contact with the inner wall and the inner liner; A driving assembly is located in the reaction chamber, the driving assembly is fixedly connected to the baffle, the inner wall and lining of the reaction chamber are part of the radio frequency circuit of the plasma processing equipment, and the driving assembly is used to move the baffle along the inner wall of the reaction chamber to adjust the capacitance between the inner wall and lining of the reaction chamber.

2. The device according to claim 1, characterized in that The baffle is annular and is divided into at least two arc-shaped plates in the circumferential direction of the ring. The driving assembly can control the arc-shaped plates to move separately.

3. The device according to claim 2, characterized in that At least two of the arc-shaped plates have different heights.

4. The device according to claim 2, characterized in that The baffle is made of semiconductor.

5. The device according to claim 2, characterized in that The baffle is made of metal.

6. The device according to claim 5, characterized in that The baffle is made of aluminum, and its surface is plated with nickel.

7. The device according to claim 1, characterized in that The driving assembly can also control the baffle to move in a circumferential direction and / or move up and down along the inner wall of the reaction chamber.

8. The device according to claim 7, characterized in that The drive assembly is capable of recording position data of the baffle.

9. A plasma processing device, comprising a reaction chamber and a liner located in the reaction chamber, characterized in that: It also includes the radio frequency adjustment device as described in any one of claims 1-8.

10. The device according to claim 9, characterized in that The reaction chamber is provided with a film transmission port, and the baffle can at least partially cover the film transmission port by moving.

11. A radio frequency electric field adjustment method, characterized in that The steps include: Initializing the position of the baffle in the radio frequency adjustment device according to any one of claims 1 to 8; introducing a reactive gas into a plasma processing device; Applying a radio frequency electric field to excite plasma to etch the substrate in the reaction chamber; The baffle is adjusted according to the uniformity of the surface of the etched substrate.

12. The method according to claim 11, characterized in that When adjusting the position of the baffle, the drive assembly can record the position data of the baffle for forming a visual image in an external operating system.

13. The method according to claim 11, characterized in that The following steps are also included: For a position where the etching depth is shallow on the surface of the substrate after etching, raising the baffle closest to the position; For a location on the substrate surface where the etching depth is relatively deep after etching, the baffle closest to the location is lowered.

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