Method for surface treatment of electrostatic chuck ceramics

Abstract

The present methods and apparatus reduce chucking anomalies in an electrostatic chuck by ensuring proper planarization of the ceramic surface of the electrostatic chuck. In some embodiments, a method for planarizing an upper ceramic surface of an electrostatic chuck assembly includes placing the electrostatic chuck assembly in a first planarization apparatus, modifying the upper ceramic surface of the electrostatic chuck assembly, and performing a S a The parameter of is less than about 0.1 microns, and S dr The parameter of is less than about 2.5 percent, and S z The parameters are approximately 10mm above the upper ceramic surface 2 and ceasing to modify the upper ceramic surface of the electrostatic chuck assembly when a pit porosity depth parameter is less than about 10 microns for any given area, or greater than 1 micron, is less than about 0.1 percent of the area of ​​the upper ceramic surface.

Description

[Technical Field]

[0001]

[0001] Embodiments of this principle generally relate to semiconductor processing of semiconductor substrates. [Background technology]

[0002]

[0002] Electrostatic chucks (ESCs) are used to hold semiconductor wafers for processing in a processing chamber. If the wafer moves during processing or is not properly positioned before processing, contamination and defects may occur on the wafer, potentially significantly degrading the performance of the structures formed on the wafer. As ESCs age, the static bonding force for holding the wafer to the ESC can become irregular. The inventors have observed that uneven bonding forces often lead to improper functioning of the ESC, causing misalignment of the wafer clamping, and even generating erroneous bonding forces that cause contaminants to be generated by the static clamping force remaining when the wafer is lifted from the surface of the ESC.

[0003]

[0003] Accordingly, the inventors provide improved apparatus and processes for producing higher-performance electrostatic chucks. [Overview of the project]

[0004]

[0004] This specification provides a method and apparatus for improving the performance of an electrostatic chuck ceramic surface.

[0005]

[0005] In some embodiments, a method for planarizing the upper ceramic surface of an electrostatic chuck assembly includes placing the electrostatic chuck assembly in a first planarizing device, modifying the upper ceramic surface of the electrostatic chuck assembly using the first planarizing device, and adjusting the arithmetic mean height (S) of the upper ceramic surface. a The parameter of ) is less than approximately 0.1 microns, and the developed area ratio of the interface of the upper ceramic surface (S dr The parameter of ) is less than approximately 2.5 percent, and the maximum height of the upper ceramic surface (S zThe parameter of 2 any given region to Regarding is less than about 10 microns, or when the parameter of the pit porosity depth greater than 1 micron on the upper ceramic surface is less than about 0.1 percent of the area of the upper ceramic surface, it may include stopping the modification of the upper ceramic surface of the electrostatic chuck assembly.

[0006] In some embodiments, the method electrostatic chuck assembly when the parameter of the arithmetic mean height (S a ) of the upper ceramic surface is less than about 0.1 micron and the parameter of the developed area ratio (S dr ) of the interface of the upper ceramic surface is less than about 2.5 percent ,above stopping the modification of the upper ceramic surface, wherein the first planarization device includes a bead blasting device, a polishing device, a lapping apparatus, a grinding apparatus, or a chemical mechanical planarization (CMP) device, the upper ceramic surface has a plurality of contact elements disposed thereon, the plurality of contact elements have a height between about 2 microns and about 20 microns, and the plurality of contact elements are made of a diamond like coating (DLC) material Composed of, stopping the modification of the upper ceramic surface and modifying each upper contact element surface of the plurality of contact elements using a second planarization device electrostatic chuck assembly when the parameter of the arithmetic mean height (S a ) of the upper contact element surface is less than about 0.1 micron, the parameter of the developed area ratio (S dr ) of the interface of the upper contact element surface is less than about 2.5 percent, the parameter of the maximum height (S z ) of the upper contact element surface is less than about 10 microns, or when the parameter of the pit porosity depth greater than 1 micron on the upper contact element surface is less than about 0.1 percent of the area of the upper contact element surface ,above The method involves stopping the modification of the surface of a partial contact element, wherein the second planarization apparatus includes a bead blasting apparatus, a polishing apparatus, a lapping apparatus, a grinding apparatus, or a chemical mechanical planarization (CMP) apparatus. ,above Stopping changes to the surface of the contact element and the arithmetic mean height (S) of the upper ceramic surface a ) parameters, the ratio of the developed area of ​​the interface of the upper ceramic surface (S dr ) parameters, upper ceramic surface approximately 10mm 2 Any given region Maximum height (S z To determine at least one of the parameters of ) or the pit porosity depth of the upper ceramic surface of The method further includes, using data from an in-situ surface measurement device, determining an endpoint to stop the modification of the upper ceramic surface, and / or restoring the modified electrostatic chuck assembly. hand Local center find (LCF) position operation parameters of approximately 1 mm or less Possible It is used in the upper ceramic surface refurbishment process of electrostatic chuck assemblies to produce sheet resistance (Rs) non-uniformity (NU) operating parameters of approximately 2 percent or less.

[0007]

[0007] In some embodiments, the apparatus for supporting a wafer on the upper surface of an electrostatic chuck comprises a plurality of contact elements deposited on the upper surface of the electrostatic chuck, where each of the plurality of contact elements has an upper contact element surface, the upper contact element surface having an arithmetic mean height (S) of less than about 0.1 microns. a ) parameters, interface development area ratio (S) less than approximately 2.5 percent dr ) parameters, maximum height (S) of the upper contact element surface of less than approximately 10 microns z The surface morphology has parameters of ) or parameters of a pit porosity depth greater than 1 micron, which is less than approximately 0.1 percent of the surface area of ​​the upper contact element.

[0008]

[0008] In some embodiments, the apparatus has a surface morphology with an arithmetic mean height (S) of less than approximately 0.1 microns. a ) parameters, and interface development area ratio (S) less than approximately 2.5 percent. dr ) has the parameters, each of the multiple contact elements has a height between approximately 2 microns and approximately 20 microns, and / or each of the multiple contact elements is made from a diamond-like coating (DLC) material. It is composed This could include the following.

[0009]

[0009] In some embodiments, a non-temporary computer-readable medium storing instructions that, when executed, cause to perform a method for planarizing the upper ceramic surface of an electrostatic chuck assembly, the method comprising: placing the electrostatic chuck assembly in a first planarizing device; and modifying the upper ceramic surface of the electrostatic chuck assembly using the first planarizing device. electrostatic chuck assembly Arithmetic mean height of the upper ceramic surface (S a The parameter of ) is less than approximately 0.1 microns, and the developed area ratio of the interface of the upper ceramic surface (S dr The parameter of ) is less than approximately 2.5 percent, and the parameter of the maximum height (Sz) of the upper ceramic surface is approximately 10 mm above the upper ceramic surface. 2 Any given region to Regarding When the parameter of pit porosity depth greater than 1 micron on the upper ceramic surface is less than approximately 10 microns, or less than approximately 0.1 percent of the area of ​​the upper ceramic surface. ,above This may include stopping the modification of the ceramic surface.

[0010]

[0010] In some embodiments, a method for non-temporary computer-readable media is electrostatic chuck assembly Arithmetic mean height of the upper ceramic surface (S a The parameter of ) is less than approximately 0.1 microns, and the developed area ratio of the interface of the upper ceramic surface (S drWhen the parameter of ) is less than approximately 2.5 percent ,above To stop modifying the ceramic surface of the upper part, modify the upper ceramic surface of the electrostatic chuck assembly using a first planarization device including a bead blasting device, polishing device, lapping device, grinding device, or chemical mechanical planarization (CMP) device, and to change the arithmetic mean height (S) of the upper ceramic surface. a ) parameters, the ratio of the developed area of ​​the interface of the upper ceramic surface (S dr ) parameters, upper ceramic surface approximately 10mm 2 Any given region to Regarding The maximum height of the upper ceramic surface is less than approximately 10 microns (S z To determine at least one of the parameters of ) or the pit porosity depth of the upper ceramic surface of , determining an endpoint for stopping the change using data from an in-situ measuring device, wherein the upper ceramic surface has a plurality of contact elements positioned on the upper ceramic surface, and the plurality of contact elements have heights between approximately 2 microns and approximately 20 microns, and using a second planarizing device to change the upper contact element surface of each of the plurality of contact elements, electrostatic chuck assembly The arithmetic mean height (S) of the upper contact element surface. a The parameter of ) is less than approximately 0.1 microns, and the developed area ratio of the interface of the upper contact element surface (S dr The parameter of ) is less than approximately 2.5 percent, and the maximum height (S) of the upper contact element surface is less than 2.5 percent. z When the parameter of ) is less than approximately 10 microns, or when the parameter of pit porosity depth greater than 1 micron on the upper contact element surface is less than approximately 0.1 percent of the area of ​​the upper contact element surface. ,above Stopping the modification of the surface of the subcontact element, and / or the arithmetic mean height (S) of the upper contact element surface. a ) parameters, the ratio of the developed area of ​​the interface of the upper contact element surface (S dr) parameters, maximum height (S) of the upper contact element surface of less than approximately 10 microns z To determine at least one of the parameters of the upper contact element surface, or the parameter of the pit porosity depth of the upper contact element surface. of This may further include using data from in-situ measuring devices to determine the endpoint for stopping the change.

[0011]

[0011] Other embodiments and further embodiments are disclosed below.

[0012]

[0012] Embodiments of the principle, which are briefly summarized above and described in detail below, can be understood by referring to exemplary embodiments of the principle shown in the accompanying drawings. However, since the principle may allow for other equally valid embodiments, the accompanying drawings illustrate only typical embodiments of the principle and should therefore not be considered limiting in scope. [Brief explanation of the drawing]

[0013] [Figure 1]

[0013] A method for planarizing the upper ceramic surface or top surface of a contact element of an electrostatic chuck assembly, according to several embodiments of the present principle. [Figure 2]

[0014] Cross-sectional diagrams of an electrostatic chuck and chucking force according to several embodiments of this principle are shown. [Figure 3]

[0015] The following are cross-sectional views of some electrostatic chucks with damaged ceramic surfaces and contact element surfaces, according to several embodiments of this principle. [Figure 4]

[0016] The three-dimensional morphology of the surface and related parameters according to several embodiments of this principle are shown. [Figure 5]

[0017] The three-dimensional morphology of the surface and related parameters according to several embodiments of this principle are shown. [Figure 6]

[0018] This document shows an electrostatic chuck assembly with a contact element according to several embodiments of this principle. [Modes for carrying out the invention]

[0014]

[0019] To facilitate understanding, the same reference numerals were used where possible to indicate identical elements common to multiple figures. Figures are not drawn to scale and may be simplified for clarity. Elements and features of one embodiment may be usefully incorporated into other embodiments without further description.

[0015]

[0020] This method and apparatus provide an improved electrostatic chuck (ESC) ceramic surface and / or wafer pad support surface. This improvement reduces sheet resistance non-uniformity and / or wafer positioning errors, thereby improving the chucking performance of an ESC operating on the Johnsen-Rahbek (JR) principle. The surface morphology of the ceramic surface and pad surface is modified to provide specific characteristics that enhance the performance of the ESC and to ensure stable and reliable operation of the ESC. The inventors have found that specific quantitative surface morphology characteristics result in efficient and reliable charge separation and uniformity to ensure proper chucking and dechucking of wafers on the ESC.

[0016]

[0021] Many current ESCs or substrate holders, particularly those operating on the JR principle, fail or lose effectiveness prematurely due to use or poor manufacturing tolerances. Current typical theories fail to explain why new or used ESCs fail due to loss of backside cooling gas pressure, low uniformity in wafer processing, or wafer slippage caused by uneven or unreliable chucking forces. However, the inventors have discovered that this failure mechanism is due to changes in the surface roughness or morphology of the ceramic surface of the ESC. Furthermore, the inventors have found that changes in the surface morphology of the ESC during wafer processing, such as pit deepening or widening, impair the function of the contact elements or wafer support pads. These contact elements enable uniform charge separation between the backside of the wafer and the upper ceramic surface of the ESC, which is essential for reliable and uniform chucking. The contact element also helps maintain uniform separation between the back of the wafer and the upper ceramic surface of the ESC to allow for a critical flow and uniform pressure of the back cooling gas, such as helium or argon, for example, but not limited to these. The uniform separation provided by the contact element accommodates the mean free path of the back gas, which is in the range of 2 to 8 microns when operating at pressures of 5 to 20 Torr. The height of the contact element is then set to 2 to 20 microns to ensure sufficient and uniform heat conduction through the back gas. This principle provides surface morphological parameters to ceramic surfaces and / or contact elements, such as aluminum nitride ESCs used in high-temperature metal deposition product processing, ensuring that high chucking performance of the ESC is obtained.

[0017]

[0022] An ESC operating on the JR principle is activated by applying a voltage to electrodes embedded in the ceramic surface (usually 1 mm below the ceramic surface). The electric field from the electrodes causes charge separation between the top surface of the ceramic and the bottom or back surface of the wafer. For example, when a positive voltage is applied to the electrodes, electrons are attracted to the ceramic surface, leaving positive charges on the back of the wafer. The attractive force between the separated reverse charges provides the static chucking force of the ESC. The inventors have found that if the ceramic surface becomes too rough, has too many pits, or has too much porosity, it hinders the uniform flow of charge necessary for the ceramic surface to form uniform charge separation. Furthermore, the inventors have found that non-uniform charge separation contributes to process non-uniformity = (R s We found that this can cause typical failure modes seen in JR ESCs, including NU%, chucking or dechucking problems, loss of backside cooling gas pressure, and / or wafer slip (local center find or LCF error).

[0018]

[0023] This principle can be used to quantify the morphology of ceramic surfaces and contact element surfaces, and the arithmetic mean height (S a ), interface development area ratio (S dr ), maximum height (S z ), and provide specific limitations on surface morphology parameters, including the ratio of pit porosity area to surface area, to ensure reliable and stable chucking of the substrate or wafer. The inventors found that typical measurement methods used to measure ESC surface roughness, such as stylus profilometry, do not provide sufficient detail of the surface. The inventors provided specific limitations on surface morphology parameters of the ESC surface, S a S dr S zTo render and appropriately determine the surface morphology of ESC surfaces, we discovered advanced methods such as laser confocal microscopy and atomic force microscopy (AFM), but not limited to these. These measurement methods and parameters enable better surface finishing of new ESC materials and provide reliable guidelines for refurbishment of used ESC surfaces, such as bead blasting and polishing.

[0019]

[0024] Figure 1 shows a method 100 for planarizing the upper ceramic surface of an electrostatic chuck assembly. The electrostatic chuck assembly may include a complete ESC or only the wafer support portion of the ESC. In some embodiments, the ceramic may be aluminum oxide or aluminum nitride, etc. In block 102, the electrostatic chuck assembly is placed in a first planarizing apparatus. In some embodiments, the first planarizing apparatus may be a machine-based planarizing apparatus, including a lapping apparatus, grinding apparatus, polishing apparatus, bead blasting apparatus, or chemical mechanical planarizing (CMP) apparatus. The technique of this principle is not limited by the type of planarizing apparatus. In block 104, the upper ceramic surface of the electrostatic chuck assembly is modified by the first planarizing apparatus. Specifically, the surface morphology of the upper ceramic surface is changed to a more planar state. In block 106, the modification of the upper ceramic surface of the electrostatic chuck assembly is stopped when predetermined parameters are obtained with respect to the surface morphology of the upper ceramic surface. In some embodiments, the parameters may be determined during the planarization process from an in-situ measuring device (such as a confocal laser or AFM) associated with the first or second planarization apparatus.

[0020]

[0025] In some embodiments, surface morphology measurements may be performed on the upper ceramic surface before modifying the ceramic surface in order to facilitate modification of the ceramic surface. Estimating the time to modify the process may be done by comparing the starting surface morphology parameters with predetermined surface morphology parameters, and based on the type of planarization apparatus and process. In some embodiments, stopping the modification of the upper ceramic surface of the electrostatic chuck assembly means that the arithmetic mean height (S) of the upper ceramic surface is a The parameter of ) is less than approximately 0.1 microns, and the developed area ratio of the interface of the upper ceramic surface (S dr The parameter of ) is less than approximately 2.5 percent, and the maximum height of the upper ceramic surface (S z The parameter of the upper ceramic surface is approximately 10 mm 2 This is done when the parameter of pit porosity depth greater than 1 micron on the upper ceramic surface is less than approximately 10 microns relative to the area, and / or less than approximately 0.1 percent of the area of ​​the upper ceramic surface. z The parameter is determined by an area approximately equal to the contact surface area of ​​the contact element. A typical contact element is about 10 mm. 2 It may have a contact surface area or support surface area. The inventors of the present invention have found that S z It was found that the parameters must not exceed the height of the contact element (see height 604 in Figure 6). The contact element can have a maximum height of approximately 20 microns. In some embodiments, S z The parameter is less than approximately 10 microns within any given region of the upper ceramic surface of the ESC, ensuring that adverse effects on contact elements placed within any given region are minimized.

[0021]

[0026] In some embodiments, the same surface morphology parameters can also be applied to the surface of contact elements deposited on the ceramic surface of the electrostatic chuck. That is, Method 100 modifies the upper contact element surface of each of the multiple contact elements using a second planarization device and the arithmetic mean height (S) of the upper contact element surface. aThe parameter of ) is less than approximately 0.1 microns, and the developed area ratio of the interface of the upper contact element surface (S dr This may further include stopping the modification of the upper contact element surface of the electrostatic chuck assembly when the parameter of ) is less than approximately 2.5 percent, the parameter of the maximum height (Sz) of the upper contact element surface is less than approximately 10 microns, or the parameter of the pit porosity depth greater than 1 micron on the upper contact element surface is less than approximately 0.1 percent of the area of ​​the upper contact element surface.

[0022]

[0027] In some embodiments, the second planarization apparatus may be a machine-based planarization apparatus, including a lapping apparatus, grinding apparatus, polishing apparatus, bead blasting apparatus, or chemical mechanical planarization (CMP) apparatus. The technique of this principle is not limited by the type of planarization apparatus. In some cases, the first and second planarization apparatuses may be of the same type or different types. In some embodiments, if the ceramic surface and / or contact elements satisfy predetermined parameters, method 100 restores the electrostatic chuck to a local center-find (LCF) positional operation parameter of about 1 mm or less. Possible It can be used in electrostatic chuck modification processes to either achieve a sheet resistance (Rs) non-uniformity (NU) operating parameter of approximately 2 percent or less.

[0023]

[0028] The predetermined parameters for stopping the modification process are based on the inventors' observations regarding the operation of the electrostatic chuck. As depicted in view 200A of Figure 2, the upper ceramic portion 202A of the electrostatic chuck, with the embedded electrode 208 connected to a positive DC power supply 210, generates a positive charge 218 at the embedded electrode 208. The electric field of the embedded electrode 208 induces a negative charge layer 212A on the surface 220A of the upper ceramic portion 202A. The inventors have found that when the surface morphology of the upper ceramic portion 202A satisfies or exceeds the predetermined parameters as described above, the negative charge layer 212A on the surface 222A of the upper ceramic portion 202A is evenly distributed across the surface 220A. This even distribution forms an equally opposite positive charge layer 214A on the back side 224A of the wafer 204a. The equal but opposite charge layers create an attractive force that chucks the wafer 204A into the electrostatic chuck. A minimal contact pad or contact element 206A maintains the wafer 204A separated from the surface 222A of the upper ceramic portion 202A by a distance equal to the height 220 of the contact element 206A. A small positive charge layer 216A may be formed on the upper surface of the contact element 206A.

[0024]

[0029] The inventors have discovered that if the surface 222B of the ceramic portion 202B does not satisfy the predetermined parameters described above, various charge layers become non-uniform, as shown in view 200B of Figure 2. The inventors have also discovered that if the surface imperfection exceeds the predetermined parameters described above, the negative charge layer 212B becomes non-uniform, resulting in the generation of a non-uniform positive charge layer 214B on the back side 224B of the wafer 204B, and a non-uniform small positive charge layer 216B on the upper surface of the contact element 206B. In some cases, regions with higher density charge layer interactions (attractions) can cause the wafer 204B to shift from its center (LCF error) when placed on an electrostatic chuck for processing. A shifted wafer center can lead to many processing errors, such as non-uniform deposition and etching, and can result in performance problems of the structure formed on the wafer. Furthermore, non-uniform charge layers can lead to longer residence times when the DC chucking power is removed. If the residence time is prolonged, an attractive force is generated when lifting the wafer from the electrostatic chuck, which can cause damage to the electrostatic chuck or the surface on the back of the wafer, or even cause contact elements to detach from the ceramic surface of the electrostatic chuck. Particle contamination caused by increased residence time due to the attractive force can lead to performance problems in the processed wafer.

[0025]

[0030] As shown in view 300 of Figure 3, the inventors examined the surface of the ceramic portion 202B of the electrostatic chuck and investigated different types of damage or roughness observed on the surface 222B. Some pitting 306 on the surface 222B damaged the contact element 206B either due to erosion during wafer processing or because a portion of the contact element 308 became embedded in the pits during deposition (the deposition was conformal with the underlying ceramic surface) due to conformal deposition of the contact element 206B. The damaged contact element 206B significantly reduced the performance of the contact element 206B because the support surface 310 of the contact element 206B was reduced. The inventors also found that surface damage to the ceramic portion 202B dramatically increased the optimal separation distance 302A of the opposing charge layers between the back side of the wafer 204B and the surface 222B of the ceramic portion 202B. For example, the pits 306 within the surface 222B nearly double the separation distance 302B, dramatically weakening the effect of the negative charge 304 formed on the surface at the bottom of the pits 306, reducing the holding force of the electrostatic chuck, and increasing the discharge time due to the longer path (separation distance 302B).

[0026]

[0031] The inventors attempted to use conventional contact surface shape measuring devices, such as linear stylus surface shape measuring devices, to determine roughness parameters that would significantly degrade the performance of the electrostatic chucks. However, the inventors found that the average roughness of the two electrostatic chucks was microinch or R a Even when measured to be the same, we discovered that the chucking performance of the two electrostatic chucks differed significantly. Further investigation revealed that the stylus shape measuring device would likely be unable to distinguish between surface morphologies that alter chucking performance and those that do not substantially reduce chucking performance (R a The inventors discovered that (the same measurement) is possible. The inventors explored other means of characterizing surface morphology and discovered that laser confocal microscopy enables more useful three-dimensional measurement of surface morphology. Laser confocal data allows for the measurement of multiple planes on a ceramic surface and the creation of a 3D model. From the data of the 3D model, the arithmetic mean height S can be calculated.a This will be determined. As shown in view 400A of Figure 4, its arithmetic mean height 402 consists of the absolute values ​​of the peaks 404 and valleys 406 relative to the mean plane 408. The arithmetic mean height 402 represents the arithmetic mean of the absolute vertical coordinate Z(x,y) and the evaluated area (surface area of ​​the ceramic surface). S a This can be expressed as follows (Equation 1), where A is the surface area. The inventors have found that an arithmetic mean height of 402 provides stable results regarding the surface morphology of the electrostatic chuck because it is not significantly affected by scratches, contamination, and measurement noise. Furthermore, to further evaluate the surface morphology of the electrostatic chuck, as depicted in view 400B of Figure 4, the inventors have found that the maximum height (S z )410 was found to be usable again. z This can be expressed as follows (Equation 2). Here, S p is the height of the peak, S v This represents the depth of the valley. TIFF0007834873000002.tif10170

[0027]

[0032] The inventors also further facilitate the determination of a viable surface morphology for the electrostatic chuck ceramic surface by considering the interface development area ratio S dr The evaluation was performed using the following. The interface development area ratio is the rate of increase in surface area due to roughness / pitting. The rate of increase is determined from the surface area A1504 obtained from the projected area A0502, as shown in view 500 of Figure 5. This ratio increases as the surface texture becomes finer or coarser. From the perspective of A1504 and A0502, S dr This can be expressed as follows (Equation 3). TIFF0007834873000003.tif13170 This ratio can be explicitly expressed as follows (Equation 4). TIFF0007834873000004.tif19170

[0028]

[0033] The inventors evaluated each parameter and determined the relationship between that parameter and the chucking performance of the electrostatic chuck. The surface morphology of the ceramic surface of the electrostatic chuck has an arithmetic mean height S of less than approximately 0.1 microns. a The ratio of the developed area of ​​the interface is less than approximately 2.5 percent. dr Approximately 10mm of the upper ceramic surface 2 Any given region to Regarding Maximum height S is less than approximately 10 microns. z The inventors have found that the performance of the electrostatic chuck can be improved when the pit porosity depth on the upper ceramic surface is greater than 1 micron, or less than about 0.1 percent of the area of ​​the upper ceramic surface. In some embodiments, the arithmetic mean height (S) is less than about 0.1 microns. a ) and the ratio of the developed area of ​​the interface to less than approximately 2.5 percent (S dr The combination with ) leads to a further improvement in the chucking force of the electrostatic chuck.

[0029]

[0034] The inventors discovered that surface defects that could not be detected by conventional means such as contact shape measurement or optical measurement significantly contribute to charge non-uniformity between the surface and the back of the wafer, charge separation non-uniformity between the surface and the back of the wafer, and contaminant formation (such as wafer ejection due to residual charge during de-chucking). Furthermore, the inventors discovered that these defects also affect the discharge capability of the chucking voltage when the chucking voltage potential is removed, increasing the residence time of the chucking charge, and causing the wafer to stick to the electrostatic chuck when being pulled up from the chuck after processing is complete. The inventors also discovered that pits lengthen the discharge path (see, for example, separation distance 302B in Figure 3), resulting in a longer discharge time. The inventors found that when the area of ​​pits / porous defects is determined at a depth of 1 micron 312 (see Figure 3), a significant improvement in the electrostatic chuck is achieved when the area of ​​pits / porous defects is less than 0.1 percent of the area of ​​the ceramic surface of the electrostatic chuck. Deep pits (e.g., greater than 5 microns) impair the coating of the contact elements, and pits greater than 1 micron impair electrical contact to the back surface of the wafer and electron conduction on the top surface of the ceramic, resulting in unstable or non-uniform charge separation, leading to increased Rs NU%, wafer slippage (LCF error), poor back-side gas pressure, and electrostatic chucking failures, including chucking / dechucking failures. Similarly, S a S z , and S dr The surface parameters can be set to thresholds that reduce the level of surface defects so as not to have a substantial impact on the chucking performance of the electrostatic chuck.

[0030]

[0035] The inventors also found that a similar technique of this principle can be applied to contact elements 602, as depicted in view 600 of Figure 6. Multiple contact elements 602 can be deposited on the ceramic surface 610 of the ceramic portion 608 of the electrostatic chuck. In some embodiments, the contact elements 602 may have a height 604 of about 2 to 20 microns. The height 604 of the contact elements 602 facilitates charge separation between the ceramic surface 610 of the electrostatic chuck and the wafer placed on the upper surface 606 of the contact elements 602. The contact elements 602 also uniformly separate the flow of backside gas for cooling the wafer. In some embodiments, the contact elements 602 can be deposited using materials such as a diamond-like coating (DLC). The contact elements 602 are conformally deposited on the ceramic surface 610. If the ceramic surface 610 satisfies the predetermined parameters described herein, the ceramic surface 610 may have an upper surface 606 that faithfully mimics an optimal surface based on the technique described herein.

[0031]

[0036] If the ceramic surface 610 is not prepared according to the present principle, the upper surface 606 may contain the same defects as those found on the ceramic surface 610. The inventors have found that the same surface morphology parameters can also be applied to the upper surface 606 of the contact element 602, regardless of the surface morphology of the ceramic surface 610. Providing a surface morphology to the upper surface 606 of the contact element 602 ensures that the contact element functions at a high performance level. By ensuring that the surface morphologies of both the contact element and the ceramic portion of the electrostatic chuck satisfy or exceed the parameters defined herein, the electrostatic chuck can function at the highest level by minimizing wafer positioning errors, reducing or eliminating contaminant formation, and reducing sheet resistance non-uniformity.

[0032]

[0037] The inventors believe that this principle can be applied not only to novel ESC manufacturing processes, but also to refurbishment processes for ceramic surfaces or contact element surfaces. do , Restore the modified electrostatic chuck assembly, and regarding the modified electrostatic chuck, Local center-finding (LCF) position operation parameters of approximately 1 mm or less Possible Either make it so, or generate sheet resistance (Rs) non-uniformity (NU) operating parameters of approximately 2 percent or less. that I discovered something I can do.

[0033]

[0038] Embodiments of this principle may be implemented in hardware, firmware, software, or any combination thereof. Alternatively, embodiments may be implemented as instructions stored using one or more computer-readable media, which may be read and executed by one or more processors. The computer-readable media may include any mechanism for storing or transmitting information in a format readable by a machine (e.g., a computing platform, or "virtual machines" running on one or more computing platforms). For example, the computer-readable media may include any suitable form of volatile or non-volatile memory. In some embodiments, the computer-readable media may include non-temporary computer-readable media.

[0034]

[0039] The above describes embodiments of the principle, but other embodiments and further embodiments of the principle can be devised without departing from the basic scope of the principle.

Claims

1. A method for planarizing the upper ceramic surface of an electrostatic chuck assembly, The electrostatic chuck assembly is installed inside the first planarizing device, The upper ceramic surface of the electrostatic chuck assembly is modified using the first planarization device, The arithmetic mean height (S) of the upper ceramic surface of the electrostatic chuck assembly. ａ The parameter of ) is less than 0.1 microns, and the developed area ratio of the interface of the upper ceramic surface (S ｄｒ The parameter of ) is less than 2.5 percent, and the maximum height (S) of the upper ceramic surface ｚ The parameter of the upper ceramic surface is 10 mm ２ The modification of the upper ceramic surface is stopped when the parameter of the pit porosity depth greater than 1 micron on the upper ceramic surface is less than 10 microns for any given region, or less than 0.1 percent of the area of ​​the upper ceramic surface. Methods that include...

2. The arithmetic mean height (S) of the upper ceramic surface of the electrostatic chuck assembly. ａ The parameter of ) is less than 0.1 microns, and the developed area ratio of the interface of the upper ceramic surface (S ｄｒ To stop the modification of the upper ceramic surface when the parameter of ) is less than 2.5 percent. The method according to claim 1, further comprising:

3. The method according to claim 1, wherein the first planarization apparatus includes a bead blasting apparatus, a polishing apparatus, a lapping apparatus, a grinding apparatus, or a chemical mechanical planarization (CMP) apparatus.

4. The method according to claim 1, wherein the upper ceramic surface has a plurality of contact elements disposed on the upper ceramic surface, and the plurality of contact elements have a height between 2 microns and 20 microns.

5. The method according to claim 4, wherein the plurality of contact elements are made of a diamond-like coating (DLC) material.

6. The second planarization device is used to modify the upper contact element surface of each of the plurality of contact elements, The parameter of the arithmetic mean height (S ａ ) of the upper contact element surface is less than 0.1 micron, the parameter of the developed area ratio (S ｄｒ ) of the interface of the upper contact element surface is less than 2.5 percent, the parameter of the maximum height (S ｚ ) of the upper contact element surface is less than 10 microns, or when the parameter of the pit porosity depth greater than 1 micron on the upper contact element surface is less than 0.1 percent of the area of the upper contact element surface, stopping the change of the upper contact element surface of the electrostatic chuck assembly The method according to claim 4, further comprising:

7. The method according to claim 6, wherein the second planarization apparatus includes a bead blasting apparatus, a polishing apparatus, a lapping apparatus, a grinding apparatus, or a chemical mechanical planarization (CMP) apparatus.

8. The arithmetic mean height (S) of the upper ceramic surface. ａ ) parameters, the ratio of the developed area of ​​the interface of the upper ceramic surface (S ｄｒ ) parameters, 10 mm of the upper ceramic surface ２ The maximum height (S) for any given region ｚ Using data from an in-situ surface measuring device to determine at least one of the parameters of the upper ceramic surface, or the parameter of the pit porosity depth of the upper ceramic surface, the endpoint for stopping the modification of the upper ceramic surface is determined. The method according to claim 1, further comprising:

9. The method according to claim 1, used in a process of refurbishing the upper ceramic surface of an electrostatic chuck assembly to restore a refurbished electrostatic chuck assembly to enable a local center-find (LCF) position operating parameter of 1 mm or less or to generate a sheet resistance (Rs) non-uniformity (NU) operating parameter of 2 percent or less.

10. A device for supporting a wafer on the upper surface of an electrostatic chuck, A plurality of contact elements deposited on the upper surface of the electrostatic chuck, wherein each of the plurality of contact elements has an upper contact element surface. Equipped with, The upper contact element surface has an arithmetic mean height (S) of less than 0.1 microns. ａ ) parameters, interface development area ratio (S) of less than 2.5 percent ｄｒ ) parameters, maximum height (S) of the upper contact element surface of less than 10 microns ｚ Apparatus having a surface morphology with parameters of ) or parameters of a pit porosity depth greater than 1 micron and less than 0.1 percent of the surface area of ​​the upper contact element.

11. The surface morphology has an arithmetic mean height (S) of less than 0.1 microns. ａ ) parameters, and the ratio of the developed area of ​​the interface less than 2.5 percent (S ｄｒ The apparatus according to claim 10, having the parameters of ).

12. The apparatus according to claim 10, wherein each of the plurality of contact elements has a height between 2 microns and 20 microns.

13. The apparatus according to claim 10, wherein each of the plurality of contact elements is made of a diamond-like coating (DLC) material.

14. A non-temporary computer-readable medium storing instructions for performing a method for planarizing the upper ceramic surface of an electrostatic chuck assembly, wherein the method The electrostatic chuck assembly is installed inside the first planarizing device, The upper ceramic surface of the electrostatic chuck assembly is modified using the first planarization device, The arithmetic mean height (S) of the upper ceramic surface of the electrostatic chuck assembly. ａ The parameter of ) is less than 0.1 microns, and the developed area ratio of the interface of the upper ceramic surface (S ｄｒ The parameter of ) is less than 2.5 percent, and the maximum height (S) of the upper ceramic surface ｚ The parameter of the upper ceramic surface is 10 mm ２ The modification of the upper ceramic surface is stopped when the parameter of the pit porosity depth greater than 1 micron on the upper ceramic surface is less than 10 microns for any given region, or less than 0.1 percent of the area of ​​the upper ceramic surface. Non-temporary computer-readable media, including [specific examples of such media].

15. The arithmetic mean height (S) of the upper ceramic surface of the electrostatic chuck assembly. ａ The parameter of ) is less than 0.1 microns, and the developed area ratio of the interface of the upper ceramic surface (S ｄｒ To stop the modification of the upper ceramic surface when the parameter of ) is less than 2.5 percent. A non-temporary computer-readable medium according to claim 14, further comprising:

16. Modify the upper ceramic surface of the electrostatic chuck assembly using the first planarization apparatus, which includes a bead blasting apparatus, polishing apparatus, lapping apparatus, grinding apparatus, or chemical mechanical planarization (CMP) apparatus. A non-temporary computer-readable medium according to claim 14, further comprising:

17. The arithmetic mean height (S) of the upper ceramic surface ａ ) parameters, the ratio of the developed area of ​​the interface of the upper ceramic surface (S ｄｒ ) parameters, 10 mm of the upper ceramic surface ２ For any given region, the maximum height (S) of the upper ceramic surface is less than 10 microns. ｚ Using data from an insitu measuring device to determine at least one of the parameters of the upper ceramic surface, or the parameter of the pit porosity depth of the upper ceramic surface, the endpoint for stopping the change is determined. A non-temporary computer-readable medium according to claim 14, further comprising:

18. The non-temporary computer-readable medium according to claim 14, wherein the upper ceramic surface has a plurality of contact elements disposed on the upper ceramic surface, and the plurality of contact elements have a height between 2 microns and 20 microns.

19. Using a second flattening device, the upper contact element surface of each of the plurality of contact elements is modified, The arithmetic mean height (S) of the upper contact element surface. ａ The parameter of ) is less than 0.1 microns, and the developed area ratio of the interface of the upper contact element surface (S ｄｒ The parameter of ) is less than 2.5 percent, and the maximum height (S) of the upper contact element surface is less than 2.5 percent. ｚ The modification of the upper contact element surface of the electrostatic chuck assembly is stopped when the parameter of is less than 10 microns, or when the parameter of the pit porosity depth greater than 1 micron on the upper contact element surface is less than 0.1 percent of the area of ​​the upper contact element surface. A non-temporary computer-readable medium according to claim 18, further comprising:

20. The arithmetic mean height (S) of the upper contact element surface ａ ) parameters, the ratio of the developed area of ​​the interface of the upper contact element surface (S ｄｒ ) parameters, the maximum height (S) of the upper contact element surface of less than 10 microns ｚ Using data from an in-situ measuring device to determine at least one of the parameters of the upper contact element surface, or the parameter of the pit porosity depth of the upper contact element surface, the endpoint for stopping the change is determined. A non-temporary computer-readable medium according to claim 19, further comprising:

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