Edge ring height measurement device and method

Abstract

The present invention provides an edge ring height measurement device and method, comprising a carrier plate with positioning points placed on an electrostatic suction cup, and an imaging device on the carrier plate. The image of the edge ring is obtained multiple times by the imaging device, and then the height or thickness change of the edge ring is calculated after data processing. The change data is conducive to the adjustment of the edge ring loss. The error can be reduced by measuring multiple points in different areas. There is no need to destroy the original vacuum environment, which greatly reduces the stagnation time consumed by the edge ring adjustment.

Description

Technical Field

[0001] The present invention relates to the technical field of plasma etching, and in particular to an edge ring height measurement device and method. 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 the plasma treatment process step, which is carried out inside a reaction chamber into which process gases are input. A radio frequency source is inductively and / or capacitively coupled to the interior of the reaction chamber to excite the process gas to form and maintain a plasma. Inside the reaction chamber, the exposed substrate is supported by a lower electrode assembly and fixed in a fixed position by a clamping force to ensure the safety of the substrate during the process and a high yield of the processing.

[0003] The lower electrode assembly includes not only an electrostatic chuck for fixing the substrate and a base for supporting the electrostatic chuck, but also an edge ring assembly arranged around the base. During the process of processing the substrate, the lower electrode assembly is used not only to support and fix the substrate, but also to control the temperature, electric field distribution, etc. of the substrate.

[0004] In the prior art, an edge ring assembly can be used to adjust the bombardment effect of plasma on the substrate. When the edge ring is worn during use, it will affect the pre-designed plasma etching conditions, resulting in reduced uniformity.

[0005] There are two common solutions to this situation: one is to replace the edge ring every time it is damaged, and the other is to change the edge ring parameters to compensate. The first method is more expensive, and each replacement causes production stagnation. The second method has problems with the timing and amount of change. If the vacuum chamber is opened every time to measure the edge ring rise, it will undoubtedly cause production stagnation, so it is necessary to accurately measure the edge ring changes while minimizing the stagnation time. Summary of the invention

[0006] In order to solve the above technical problems, the present invention provides an edge ring height measurement device for measuring the height change of an edge ring arranged around an electrostatic chuck on an electrostatic chuck in a plasma reaction chamber, comprising:

[0007] an imaging device for acquiring an image of the limbal ring;

[0008] The carrying plate of the imaging device can be placed on the electrostatic chuck, and the carrying plate has a positioning point.

[0009] Optionally, a light source is also included.

[0010] Optionally, the imaging device includes:

[0011] A camera located on the carrier plate, the lens of which can be aligned with the upper surface of the edge ring;

[0012] A control device connected to the camera is used for wireless communication with external equipment.

[0013] Optionally, there are at least four cameras, corresponding to different areas of the edge ring respectively.

[0014] Optionally, the imaging device includes a plane mirror assembly located on the carrier plate.

[0015] Optionally, the plane mirror assembly includes a plane mirror and a bracket, and the imaging device further includes an adjustment device electrically connected to the bracket for adjusting the tilt angle of the plane mirror.

[0016] Optionally, the imaging device further comprises an image analyzer located outside the reaction chamber, and the image analyzer can obtain the image of the edge ring formed by the plane mirror through the window of the reaction chamber.

[0017] Optionally, the imaging device is fixedly connected to the carrier plate, and the positioning point is used to ensure that two adjacent images acquired by the imaging device belong to the same area of ​​the edge ring.

[0018] Optionally, the edge ring includes a focus ring.

[0019] Furthermore, a plasma processing system is provided, comprising a process chamber, a transmission chamber and a storage chamber, and comprising any one of the measuring devices described above.

[0020] Optionally, the measuring device may be transferred between the process chamber and the storage chamber through the transmission chamber.

[0021] Furthermore, a method for measuring edge ring height variation is provided, comprising the following steps:

[0022] Step 1: before the reaction, placing any one of the above-mentioned measuring devices into a plasma reaction chamber to obtain a height image of the edge ring;

[0023] Step 2: after the reaction, placing any one of the above-mentioned measuring devices into a plasma reaction chamber to obtain a height image of the edge ring;

[0024] Step three, comparing the images obtained in step one and step two, and calculating the height change of the edge ring.

[0025] Optionally, the height image acquired in step one is the initial height of the edge ring, and the height change calculated in step three is the total change of the edge ring height relative to the initial height.

[0026] Optionally, the height change calculated in step three is a change in height images acquired two adjacent times.

[0027] Optionally, the height image of step 2 is: obtaining multiple height images of the same area of ​​the edge ring.

[0028] Optionally, the height image of step 2 is: obtaining height images of different areas of the edge ring.

[0029] Optionally, the change in height of the edge ring is used to adjust the height of the edge ring.

[0030] Optionally, the height variation of the edge ring is used to adjust the capacitance value of the circuit in which the edge ring is located.

[0031] The advantages of the present invention are as follows: the present invention provides a device for measuring the height of an edge ring, which can collect data on the change in the height of the edge ring, and can reduce errors by measuring multiple points in different areas, estimate the degree of damage to the edge ring, and provide more accurate support for subsequent adjustment of the edge ring. In addition, the measuring device can be placed on a substrate rack inside a machine, and can be sent into a reaction chamber for measurement by a robot and then taken out, and then data can be transmitted with an external system through a communication module, without destroying the original vacuum environment, thereby greatly reducing the dead time consumed by the edge ring adjustment and improving production efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] 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.

[0033] Figure 1 A schematic structural diagram of a capacitively coupled plasma processing device is shown;

[0034] Figure 2 An edge ring height measurement device according to an embodiment is shown;

[0035] Figure 3 Another embodiment of an edge ring height measuring device is shown. DETAILED DESCRIPTION

[0036] 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.

[0037] Figure 1 A schematic diagram of a capacitively coupled plasma processing device is shown, including a vacuumable reaction chamber 100 surrounded by an outer wall 10. The reaction chamber 100 is used to process a substrate 103. The reaction chamber includes a lower electrode assembly for supporting the substrate while controlling the substrate temperature, electric field and other factors affecting the substrate processing. The lower electrode assembly includes a base 101 for carrying an electrostatic chuck 102. The base 101 is provided with a temperature control device for controlling the temperature of the upper substrate. The electrostatic chuck 102 is used to carry the substrate 103. A DC electrode is provided inside the electrostatic chuck, and DC adsorption is generated between the back of the substrate and the bearing surface of the electrostatic chuck through the DC electrode to fix the substrate. An edge ring assembly 20 is provided around the base and the periphery of the electrostatic chuck to adjust the temperature and electric field distribution of the edge area of ​​the substrate. A plasma confinement ring 108 is arranged around the edge ring assembly 20, located between the edge ring assembly 20 and the side wall of the reaction chamber, and is used to confine the plasma to the reaction area while allowing gas to pass through; a grounding ring 109 is located below the plasma confinement ring, and is used to provide electric field shielding to prevent plasma leakage. A bias RF power supply usually applies a bias RF signal to the lower electrode assembly to control the bombardment direction of the plasma.

[0038] exist Figure 1 In the capacitively coupled plasma processing apparatus shown, in addition to the lower electrode assembly, an upper electrode assembly is also included, and the upper electrode assembly includes a gas shower head 30 for introducing the process gas in the gas supply device into the reaction chamber. A high-frequency radio frequency power source applies a high-frequency radio frequency signal to at least one of the upper electrode assembly or the lower electrode assembly to form a radio frequency electric field between the upper electrode assembly and the lower electrode assembly, and excites the process gas in the reaction chamber into plasma, so as to achieve plasma processing of the substrate to be processed.

[0039] like Figure 2An edge ring measurement device is shown, the edge ring assembly 20 includes a focus ring 201, which can adjust the shape of plasma to make etching more uniform, but as the number of reactions increases, the focus ring 201 will be corroded by the plasma, causing its surface morphology, especially the height, to change, and thus the shape of the plasma will also change, so in order to ensure the uniformity of etching of multiple substrates, it is necessary to compensate the focus ring 201 by inserting the pin 202 in the insert ring 203, so that the adjustment degree of the focus ring 201 to the plasma remains unchanged. However, in order to obtain the adjustment amount of the focus ring 201, it is usually necessary to open the vacuum chamber, measure the actual loss of the focus ring 201, and then perform the vacuum operation after adjustment, which causes the etching process to stagnate and reduces the production efficiency. In the edge ring height measurement device of the present invention, a carrier plate 112 is included on the electrostatic chuck 102, which is not limited to a disk shape, but can also be other polygons. In some embodiments, the carrier plate 112 is the same size and shape as the substrate 103, and there are positioning points on the carrier plate 112, which can ensure that the position is controllable each time it is placed on the electrostatic chuck 102. For example, the carrier plate 112 can be controlled to be placed the same as the last time, or the carrier plate can be controlled to rotate the same angle each time. An imaging device is placed on the carrier plate 112. In this embodiment, the imaging device includes a camera 111. The lens of the camera 111 can be aligned with the upper surface of the focus ring 201, so that the damage degree of the focus ring 201 can be captured each time an image is acquired. By comparing the captured images, the height change of the focus ring 201 can be calculated. In some embodiments, the camera 111 is located at the edge of the carrier plate 112, as close to the focus ring 201 as possible; in some other embodiments, the lens axis of the camera 111 can also be located on the diameter of the carrier plate 112 in the disc-shaped embodiment, so that its lens can face a local area of ​​the focus ring 201. The imaging device also includes a control device 114, which is used to control the shooting timing of the camera 111 and transmit the image data to the external system for calculating the height change of the focus ring 201. In some embodiments, the control device 114 can be connected to the external system by wireless communication to realize shooting control and data transmission, or it can automatically shoot through a program that has been written uniformly. In other embodiments, the number of cameras 111 can be 4, evenly distributed on the edge of the carrier plate 112, so that the shooting data can cover the entire upper part of the focus ring 201. The cameras 111 can also be arranged according to the actual focus ring 201. The vulnerable position is aimed at different vulnerable positions on the focus ring 201. The measuring device can also include a light source 113, which is used to provide light compensation in the reaction chamber to improve the shooting resolution.

[0040] like Figure 3Another embodiment of the measuring device of the present invention is shown, which is different from the first embodiment in that the imaging device includes a plane mirror assembly, which is used to reflect the upper image of the focusing ring 201 to the outside of the reaction chamber 100 and then measure the change in height or thickness. In this embodiment, the plane mirror assembly includes a plane mirror 211, as shown by the dotted line in the figure, the plane mirror 211 can reflect the upper image of the focusing ring 201 to the outside of the reaction chamber 100 through the window on the outer wall 10, and then use the image analyzer 216 to obtain the device to calculate the reflected image. In some embodiments, the window can be a substrate 13 transmission window of the reaction chamber 100. The plane mirror assembly also includes a bracket 215, which is fixedly connected to the plane mirror 211 and can be connected to an external system by wireless to control the deflection angle of the plane mirror 211 to select the best reflection angle to obtain a clear image.

[0041] Furthermore, the present invention also provides a plasma processing system, including a process processing chamber for etching and other process processes, a transmission chamber for accommodating a robot to transfer substrates or other equipment from each chamber, and a storage chamber for storing substrates or other equipment for the robot to pick up and place. The processing chamber, the transmission chamber and the storage chamber can be in the same vacuum environment. The processing system also includes any of the above-mentioned edge ring height measuring devices, and the measuring device can be stored in the storage chamber. When in use, the measuring device is taken out of the storage chamber and placed into the corresponding process processing chamber by the robot in the transmission chamber, and then put back into the storage chamber after measurement. In this way, the edge ring height can be measured without opening the entire system to destroy the vacuum environment.

[0042] Furthermore, the present invention also provides a method for measuring edge ring height variation, which mainly comprises the following steps:

[0043] Step 1: before the reaction, placing any one of the above-mentioned edge ring height measurement devices into a plasma reaction chamber to obtain a height image of the edge ring;

[0044] Step 2: after the reaction, placing any one of the edge ring height measurement devices mentioned above into a plasma reaction chamber to obtain a height image of the edge ring;

[0045] Step three, comparing the images obtained in step one and step two, and calculating the height change of the edge ring.

[0046] In some embodiments, in step 1 and step 2, the average value of the edge ring height of the region can be calculated by taking multiple images of the same region, or the average value of the overall height change of the edge ring can be calculated after taking images of different regions, or a certain region can be selected to take multiple images to calculate the average value, and then the average values ​​of multiple different regions can be averaged to calculate the edge ring height value. Specifically, the positioning points on the carrier plate 112 can be used to enable the imaging device to be aimed at the same region each time, or to control the rotation angle to aim at different regions. In other embodiments, the height change calculated in step 3 is the edge ring height change obtained by taking the difference between the initial value of the edge ring height obtained in step 1 and the edge ring height value obtained in step 2 after each reaction; steps 1 and 2 can also be regarded as images obtained before and after a single reaction, and step 3 is the edge ring height change calculated for the images obtained from two adjacent single reactions.

[0047] For the acquired edge ring image, the height can be converted by pixel unit without obtaining the actual height value, and then the relative height or the change of relative height after conversion is coupled with the compensation value that needs to be adjusted for the edge ring, and the external adjustment system controls the insertion pin 202 according to the measurement result fed back each time. In some embodiments, the insertion pin 202 can have a lifting function, and the edge ring is lifted according to the measurement result for physical compensation of the height; in other embodiments, the insertion pin 202 can be a conductor, one end of which contacts the edge ring, and the other end is connected to a group of adjustment capacitors, or the insertion pin 202 and the insertion ring 203 are both conductors, and the insertion pin 202 does not need to penetrate the insertion ring 203, and only needs to contact the insertion ring 203 with the edge ring, one end of the insertion pin 202 contacts the insertion ring 203, and the other end is connected to a group of adjustment capacitors, and the capacitance is adjusted according to the measurement result to change the overall capacitance value, and the electrical compensation of the edge ring is performed. In this way, the technical effect of maintaining the uniformity of plasma etching without opening the overall vacuum system is achieved.

[0048] The edge ring height measuring device disclosed in the present invention is not limited to being applied to the plasma processing device in the above-mentioned embodiment, but can also be applied to other plasma processing devices, which will not be described in detail here.

[0049] 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. An edge ring height measuring device, used for measuring the height change of an edge ring arranged around an electrostatic chuck on an electrostatic chuck in a plasma reaction chamber, wherein the highest point of the edge ring has a highest upper surface and an inner side surface connected to the highest upper surface, the plasma reaction chamber can be in the same vacuum environment as a storage chamber and a transmission chamber, and the measuring device can be transferred between the storage chamber and the plasma reaction chamber, characterized in that: include: an imaging device for acquiring an image of the limbal ring; A carrier plate can be placed on the electrostatic suction cup, and the carrier plate has a positioning point, and the positioning point is used to limit the outer edge of the carrier plate not exceeding the inner side surface when the carrier plate is on the upper surface of the electrostatic suction cup. The imaging device is fixedly connected to the top of the carrier plate, so that the imaging device can enter and exit the plasma reaction chamber with the carrier plate.

2. The measuring device according to claim 1, characterized in that Also includes a light source.

3. The measuring device according to claim 1, characterized in that The imaging device comprises: A camera located on the carrier plate, the lens of which can be aligned with the upper surface of the edge ring; A control device connected to the camera is used for wireless communication with external equipment.

4. The measuring device according to claim 3, characterized in that There are at least four cameras, corresponding to different areas of the edge ring respectively.

5. The measuring device according to claim 1, characterized in that The imaging device includes a plane mirror assembly located on the carrier plate.

6. The measuring device according to claim 5, characterized in that The plane mirror assembly comprises a plane mirror and a bracket, and the imaging device further comprises an adjusting device electrically connected to the bracket for adjusting the tilt angle of the plane mirror.

7. The measuring device according to claim 6, characterized in that The imaging device further comprises an image analyzer located outside the reaction chamber, and the image analyzer can obtain the image of the edge ring formed by the plane mirror through the window of the reaction chamber.

8. The measuring device according to claim 1, characterized in that The imaging device is fixedly connected to the carrier plate, and the positioning point is used to ensure that two consecutive images acquired by the imaging device belong to the same area of ​​the edge ring.

9. The measuring device according to claim 1, characterized in that The edge ring includes a focus ring.

10. A plasma processing system, comprising a process chamber, a transmission chamber and a storage chamber, characterized in that: Comprising a measuring device as described in any one of claims 1-9.

11. The processing system according to claim 10, characterized in that The measuring device can be transferred between the process chamber and the storage chamber through the transfer chamber.

12. A method for measuring edge ring height variation, characterized in that: The following steps are involved: Step 1: before the reaction, placing the measuring device as described in any one of claims 1 to 9 into a plasma reaction chamber to obtain a height image of the edge ring; Step 2: after the reaction, placing the measuring device according to any one of claims 1 to 9 into a plasma reaction chamber to obtain a height image of the edge ring; Step three, comparing the images obtained in step one and step two, and calculating the height change of the edge ring.

13. The measuring method according to claim 12, characterized in that: The height image obtained in step one is the initial height of the edge ring, and the height change calculated in step three is the total change of the edge ring height relative to the initial height.

14. The measuring method according to claim 12, characterized in that: The height change calculated in step three is the change in height images acquired between two adjacent times.

15. The measuring method according to claim 12, characterized in that: The height image of step 2 is: obtaining multiple height images of the same area of ​​the edge ring.

16. The measuring method according to claim 12, characterized in that: The height image of step 2 is: obtaining height images of different areas of the edge ring.

17. The measuring method according to claim 12, characterized in that: The change in height of the edge ring is used to adjust the height of the edge ring.

18. The measuring method according to claim 12, characterized in that: The height variation of the edge ring is used to adjust the capacitance value of the circuit where the edge ring is located.

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