TWI804819B - Method of removing particles - Google Patents

Abstract

A method of removing particles includes providing charges onto a surface of a stage and one particle on the surface, moving a cleaning unit toward the surface, and moving the cleaning unit away from the surface. Providing charges onto the surface of the stage and the particle on the stage makes the surface and the particle have the negative charge concurrently. The cleaning unit with an electrostatic-attraction film enables the particle having the negative charge to move toward and adsorb on the electrostatic-attraction film.

Description

Methods of removing particles

The present disclosure is about a method of removing particles.

Semiconductor integrated circuits have experienced exponential growth, resulting in multiple generations of integrated circuits, each of which has smaller and more complex circuits than the previous generation. During the evolution of integrated circuits, functional density (that is, the number of interconnected elements per die area) typically increases, while geometry size (that is, the smallest component or line that can be produced in a process) increases. Shrinking. Generally speaking, the size reduction process can increase production efficiency and reduce manufacturing costs, but the size reduction also increases the complexity of manufacturing and producing integrated circuits. As the design of integrated circuits has become increasingly complex, its critical dimension ( critical dimension (CD) has been correspondingly reduced, resulting in a reduction in the allowable relative displacement of the layers in the integrated circuit element.

According to some embodiments of the present disclosure, a method of removing particles includes providing a charge to a surface of a support and to particles on the surface, moving a cleaning element closer to the surface, and moving the cleaning element away from the surface. Providing charges on the surface of the support base and the particles on the surface can make the surface of the support base and the particles on the surface have the same negative charge. The cleaning element has an electrostatic adsorption layer, so that the particles with electronegative electricity move toward the cleaning element and are adsorbed on the electrostatic adsorption layer.

According to other embodiments of the present disclosure, a method of removing particles includes moving a charging device onto a surface of a support, the charging device providing a first charge to the surface and at least one particle on the surface, and the charging device providing a second charge onto the cleaning element, move the cleaning element closer to the surface, and move the cleaning element away from the surface. The charging device provides a first charge to impart a first electrical property to the surface and particles on the surface, and a second electrical charge to impart a second electrical property to the cleaning element different from the first electrical property. The cleaning element having the second electrical property moves the particles having the first electrical property toward and adsorbs on the cleaning element.

According to other embodiments of the present disclosure, a method for removing particles includes moving a charging device onto a surface of a support, charging the device to provide charges to the particles on the surface, preparing a substrate, placing an electrostatic adsorption layer on the substrate, by The surface of the substrate relatively close to the support seat is moved by the transfer robot arm, the particles on the surface are adsorbed to the electrostatic adsorption layer, and the surface of the substrate relatively far away from the support seat is moved by the transfer robot arm. The charging device provides charges to the particles on the surface so that the particles have a first potential. The substrate has a second potential, wherein there is a first potential difference between the second potential and the first potential. The electrostatic adsorption layer has a third potential, wherein there is a second potential difference between the third potential and the first potential, and the second potential difference is greater than the first potential difference.

When an element is referred to as being "on", it can generally mean that the element is directly on other elements, or there may be other elements present in between. Conversely, when an element is said to be "directly on" another element, it cannot have other elements in between. As used herein, the word "and/or" includes any combination of one or more of the associated listed items.

Furthermore, in order to facilitate the description of the relationship between an element or feature part and another (some) element or feature part in the illustrations, spatial relative terms may be used, such as "below", "under", "lower part" , "above", "upper" and similar terms. Spatial terms also encompass different orientations of the device in use or operation in addition to the orientation depicted in the illustrations. When the device is turned in a different orientation (for example, rotated 90 degrees or otherwise), the spatially relative adjectives used therein shall also be interpreted in terms of the turned orientation.

As the scaling trend continues, alignment and overlay issues during process or measurement become more challenging due to ever-shrinking component sizes. Small alignment or overlay errors during processing can lead to wafer failure. Various components and techniques have been used to reduce misalignment during manufacturing. For example, alignment marks can be used to ensure proper alignment between wafers as they are loaded into semiconductor fabrication tools. In another embodiment, a wafer level correction system may be used to ensure that the wafer is level during fabrication. However, particles generated by various processes may still cause alignment problems in semiconductor processing, especially when these particles are on the surface of the wafer and/or the reticle support. Accordingly, some embodiments of the present disclosure provide a method of removing particles from the surface of a wafer and/or a reticle support.

FIG. 1 schematically illustrates a flowchart 100 for determining when to clean a wafer and/or a reticle support according to some embodiments of the present disclosure. The wafer and/or reticle holder cleaning step 108 can be used after any parameter conversion stage, such as after changing different wafer/reticle types in step 102, after performing periodic maintenance of equipment in step 104, or after performing step 106 After equipment maintenance. Before placing the target wafer and/or the photomask on the support, perform step 108 to clean the support to remove particles on the support. After the cleaning in step 108 is completed, proceed to step 110 to place the wafer and/or the photomask on the support seat and perform related processes, tests or analysis on the target wafer and/or photomask. The flow chart 100 provides a flow chart for determining when to clean the support base. When there is any other opportunity to clean the wafer and/or mask support base, step 108 can be performed at any time.

Objects that can be placed on the support base include wafers, masks, or any other objects that need to be maintained horizontally in the process. The support base can be a wafer stage/table, a mask stage/table, an electrostatic chuck (e-chuck), or other devices with the same concept. The area of the support seat is larger than that of the wafer and/or the mask. The diameter of the wafer may be about 200 mm, about 300 mm, about 450 mm, or any suitable size. In some embodiments, the wafer stage is designed with a plurality of wafer support pins that move individually (independent of each other) and vertically (perpendicular to the surface of the wafer supported thereon). In other embodiments, the electrostatic chuck is designed as a device that uses electricity to generate electrostatic forces, such as Coulomb force and Johnsen-Rahbek force, used to hold wafers and/or or mask position.

In some embodiments, the wafer may be a bulk semiconductor wafer. For example, wafers may include silicon wafers. Wafers may contain silicon or another elemental semiconductor material such as germanium. In some embodiments, the wafer may include compound semiconductors. The compound semiconductor may include gallium arsenide, silicon carbide, indium arsenide, indium phosphide, other suitable materials, or combinations thereof. However, in other embodiments, the wafer may include alloy semiconductors such as silicon germanium, silicon germanium carbide, gallium arsenic phosphide, or gallium indium phosphide. indium phosphide). In other embodiments, the wafer may include silicon-on-insulator (SOI) or germanium-on-insulator (GOI) substrates. The SOI substrate can be made by separation by implantation of oxygen technology, wafer bonding technology, other suitable technologies, or a combination of the above.

In some embodiments, the wafer includes an undoped substrate. In other embodiments, the wafer includes a doped substrate, such as a p-type substrate or an n-type substrate.

In some embodiments, the wafer contains different doped regions according to the design requirements of the semiconductor device structure. The doped regions may include p-wells and/or n-wells. In some embodiments, the doped region refers to doping with p-type dopant, for example, the doped region may be doped with boron or boron fluoride. n-type dopants such as phosphorus or arsenic. In some embodiments, part of the doped region is p-type doped and another part is n-type doped.

In some embodiments, interconnect structures may be formed on the wafer. The interconnection structure may include multiple layers of interlayer dielectric layers and dielectric layers. The interconnection structure may also include multilayer conductive features formed between interlayer dielectric layers, such as conductive lines, conductive vias, and/or various conductive contacts.

In some embodiments, the wafer has different device elements. For example, device elements may include transistors (such as metal oxide semiconductor field effect transistors (MOSFETs), complementary metal oxide semiconductor (CMOS) transistors, dual Polar junction transistor (bipolar junction transistor, BJT), high-voltage transistor (high-voltage transistor), high-frequency transistor (high-frequency transistor), p-channel and/or n-channel field-effect transistor (PFET and /or NFET), diodes, or other suitable components). Different device elements may use different process methods, including deposition, etching, implantation, lithography, annealing, and/or other suitable process methods.

In some embodiments, device elements in a wafer may be connected to each other via interconnect structures to form an integrated circuit device. Integrated circuit devices may include logic devices, memory devices (such as static random access memory (SRAM)), radio frequency (radio frequency, RF) devices, input/output (input /output (I/O)) device, a system-on-chip (SOC) device, an image sensor (image sensor) device, other suitable devices, or a combination of the above devices.

In some embodiments, the reticle may include a reflective mask. The structure of the photomask includes a substrate made of a suitable material, such as a low thermal expansion material (LTEM) or fused quartz. In various embodiments, the low thermal expansion material includes titanium dioxide (TiO ₂ ), doped silicon dioxide (SiO ₂ ), or other suitable materials with low thermal expansion. The photomask may further include reflective multiple layers deposited on the substrate. Reflective multilayer films may include several film pairs, for example, molybdenum-silicon (Mo/Si) film pairs (for example, in each film pair, a molybdenum layer is located on a silicon layer above or below), or molybdenum-beryllium (molybdenum-beryllium, Mo/Be) thin film pair, or other suitable materials that highly reflect light.

Refer to FIG. 2A , which is an exemplary front view of a support base according to some embodiments of the present disclosure, wherein a partially enlarged M1 of the dotted box in FIG. 2A is shown in FIG. 2B . The support base 200 in FIGS. 2A and 2B is a simplified diagram of an exemplary wafer carrier, and the support base 200 includes wafer support pins 205 . In other embodiments, the wafer support pins 205 may not be provided on the support base 200' in FIG. 2C and FIG. 2D. Furthermore, the operation steps of each stage applied to the support base 200 in FIG. 2A and FIG. 2B can also be applied to the support base 200' in FIG. 2C and FIG. 2D. Descriptions of the same elements discussed in the figures apply directly to the other figures unless otherwise stated.

In some embodiments, after the support base 200 passes through one or more semiconductor processes, some particles 204 inevitably adhere to the surface 202 of the support base 200 . These particles 204 may come from particles in the gas, pollutants generated during the process, particles originally attached to the wafer, or other particle-generating conditions. These particles 204 may cause alignment problems in semiconductor manufacturing and produce defective wafers.

Before removing the particles, the electrical properties of the support base 200 and the electrical properties of the particles 204 on the surface 202 of the support base 200 are substantially in an electrically neutral state. In other words, as shown in FIG. 2B and FIG. 2D , the number of first positive charges 206 on the support base 200 or the support base 200 ′ is substantially equal to the number of first negative charges 208 , and the first negative charges on the particles 204 The number of positive charges 206 and the number of first negative charges 208 are also substantially equal.

It should be noted that in order to simplify the presentation of the diagrams, the size, number, location, shape, combination, or other physical characteristics of any positive and negative charges in the diagrams have been adjusted to present positive charges in the diagrams Illustrative symbol of electricity with negative charge. Furthermore, the support base depicted in this disclosure as support base 200 with wafer support pins 205 is by way of example only and is not intended to be limiting. The purpose of the support base is to place any object that needs to be maintained level, such as a wafer or a photomask, so devices serving the same purpose are within the spirit and scope of the present disclosure.

Step 108 of flowchart 100 in FIG. 1 can be achieved by the methods of the present disclosure for removing particles from the surface of the wafer and/or the support pad of the reticle. FIG. 3 is a flowchart illustrating a method 300 of removing particles from surfaces of wafer and/or reticle support seats according to some embodiments of the present disclosure. Each step in the method 300 corresponds to Fig. 4A, Fig. 5A and Fig. 6A respectively. For example, as shown in step 302 of the method 300 and FIG. 4A , the charging device 400 provides an electric charge 402 onto the surface 202 of the support base 200 . For example, as shown in step 304 and FIG. 5A, the cleaning element 500 is moved close to the support base 200, so that the particles 204 on the surface 202 of the support base 200 approach the cleaning element 500 and are attracted to the electrostatic adsorption layer 504 of the cleaning element 500. For example, as shown in step 306 and FIG. 6A , the cleaning element 500 is moved away from the support base 200 .

Referring to FIG. 4A , a simplified front view of step 302 of method 300 is shown: charging device 400 provides charge 402 to surface 202 of support 200 and particles 204 on surface 202 . In FIG. 4A, the charging device 400 also includes a transmission system of the mobile charging device 400, a control system for providing the electric charge 402, and/or other devices. For simplicity of illustration, the above-mentioned system or device is not shown in Fig. 4A.

In some embodiments, the charging device 400 moves above the support base 200 , and can provide the charge 402 to the surface 202 of the support base 200 and the particles 204 on the surface 202 in a manner similar to spraying. In some embodiments, the wafer support pin 205 may remain protruding during the charging device 400 spraying the charge 402 . In some embodiments, the spraying cross-sectional area of the charge 402 sprayed by the charging device 400 is equal to or larger than the placement area of the target, such as a wafer, a photomask, or other targets that need to be maintained horizontally, so as to reduce the contamination of the target by particles 204 and /or alignment issues. The partial enlargement M3 of the dotted box in Fig. 4A is shown in Fig. 4B.

The charging device 400 provides charges 402 , wherein the charges of the charging device 400 come from charged particles, such as electrons, ions, or plasma, or other suitable charged particles.

The charging device 400 can be an electron gun, an ion generator, a plasma generator, other technologies for providing charged particles, or a combination thereof.

Referring to Fig. 4B, a partially enlarged M3 front view of Fig. 4A is shown. The charge 402 provided by the charging device 400 is a second negative charge 406 . In some embodiments, second negative charge 406 moves from charging device 400 to surface 202 of support stand 200 and particles 204 on surface 202 (eg, in direction 408 ). The surface 202 of the support base 200 and the particles 204 on the surface 202 each have a first positive charge 206, a first negative charge 208, and a second negative charge 406, so that the surface 202 of the support base 200 and the particles 204 on the surface 202 each have There are more negative charges than positive charges. In other words, the surface 202 of the support base 200 and the particles 204 on the surface 202 each have a negative electric charge. When the surface 202 of the support base 200 and the particles 204 on the surface 202 have negative charges respectively and simultaneously, a repulsive electrostatic force is generated between the surface 202 of the support base 200 and the particles 204 on the surface 202 . In some embodiments, an electrostatic force will be exerted on the particle 204 in a direction away from the surface 202 of the support 200 (eg, along the electrostatic force direction 410 ).

According to some embodiments of the present disclosure, providing a charge 402 (eg, a second negative charge 406 ) to the surface 202 of the support 200 and the particles 204 on the surface 202 changes the net charge of the surface 202 of the support 200 and the surface 202 The net charge of the particle 204 on the surface (that is, the charge still carried after the positive charge and the negative charge are neutralized in pairs). When the net charges of the surface 202 of the support base 200 and the particles 204 on the surface 202 are the same at the same time, for example, both are positive or negative at the same time, an electrostatic force repelling each other can be generated. In addition, the magnitude of the electrostatic force between the surface 202 of the support base 200 and the particles 204 on the surface 202 is directly proportional to the amount of net charges they possess. In some embodiments, pre-generated electrostatic repulsion between the surface 202 of the support 200 and the particles 204 on the surface 202 may be sufficient to help the particles 204 on the surface 202 to detach from the surface 202 of the support 200 in a subsequent step. attached.

FIG. 5A shows a simplified front view of step 304 of method 300 . The cleaning element 500 approaches the support base 200 (eg, direction 506 ), so that the particles 204 on the surface 202 move toward the cleaning element 500 (eg, direction 508 ) and are attracted to the electrostatic adsorption layer 504 of the cleaning element 500 . In some embodiments, the wafer transfer robot T carries the cleaning element 500 , and the cleaning element 500 approaches the support base 200 by the movement of the wafer transfer robot T. The cleaning element 500 includes a substrate 502 and an electrostatic adsorption layer 504 disposed on the substrate 502 , wherein the electrostatic adsorption layer 504 faces the support base 200 . FIG. 5A includes other systems or devices, such as a cleaning system for removing particles 204 adsorbed on the cleaning element 500 or other application systems. For simplicity of description, other systems or devices are not shown in FIG. 5A .

Continuing to refer to FIG. 5A, in some embodiments, the area of the cleaning element 500 is substantially the same as the area of the charge sprayed by the charging device 400 in step 302 of the method 300, which means that it is equal to or larger than the placement area of the target object, such as a wafer, a light source, etc. Covers, or other objects that need to be kept level. In some embodiments, the cleaning element 500 moves above the support base 200 to align with the area where the charging device 400 is sprayed in step 302 . Cleaning element 500 moves toward support base 200 (eg, direction 506 ). In some embodiments, the cleaning element 500 stops at a position above the surface 202 of the support base 200 to absorb the particles 204 without contacting the surface 202 of the support base 200 and the protruding wafer support pins 205 . In some other embodiments, the cleaning element 500 absorbs the particles 204 by contacting the surface 202 of the support base 200 and/or the protruding wafer support pins 205 . The partial enlargement M4 of the dotted box in Fig. 5A is shown in Fig. 5B.

Referring to FIG. 5B, an enlarged partial M4 front view of FIG. 5A is shown, wherein particles 204 on surface 202 have more negative charges than positive charges (e.g., first positive charge 206, first negative charge 208 , and the second negative charge 406 ), so that the particles 204 on the surface 202 have electronegative properties. The electrostatic adsorption layer 504 of the cleaning element 500 has the characteristic of attracting negative charges. In some embodiments, the electrostatic adsorption layer 504 of the cleaning element 500 has a positive charge (eg, a second positive charge 510 ). An electrostatic force of attraction is generated between the electrostatic adsorption layer 504 with positive electromagnetism and the particles 204 on the surface 202, so that the particles 204 on the surface 202 move toward the cleaning element 500 (such as direction 508) and are attracted to the electrostatic force of the cleaning element 500. on the adsorption layer 504.

In some embodiments, the substrate 502 of the cleaning element 500 is an unpatterned substrate, and the material is substantially the same as a control wafer or a dummy wafer. The substrate may include (1) crystal Silicon; (2) germanium; (3) compound semiconductors including SiC, GaAs, GaP, InP, InAs, and/or InSb; (4) alloy semiconductors including SiGe, GaAsP, AlInAs, AlGaAs, GaInAs, GaInP, GaInAsP; or ( 5) Any combination of the above.

Generally speaking, the amount of net charge possessed by each item is directly proportional to the strength of the electrostatic force between the items. The amount of net charge possessed by an item affects the potential state of the item, and the state of the electrostatic force between items can be represented by the potential difference between items. The amount of net charge (or potential state) possessed by each item has a positive relationship with the potential difference between the items. For example, in step 302, when the charging device 400 provides the charge 402 to the particle 204, the net charge amount of the particle 204 increases, thereby increasing the potential difference and the electrostatic force of attraction between the particle 204 and the cleaning element 500, so It may be helpful to drive the particles 204 to move onto the electrostatic adsorption layer 504 . In some embodiments, when the potential difference between the particles 204 and the electrostatic adsorption layer 504 is greater than about 0.1 volts, the generated electrostatic force can drive the particles 204 to move toward the cleaning element 500 and be attracted to the electrostatic adsorption layer 504 of the cleaning element 500 superior.

In step 302 , as shown in FIG. 4A , the charge 402 provided by the charging device 400 is used to control the electrical properties and quantity of the particles 204 , which helps to determine the selection of the electrostatic adsorption layer 504 . For example, when the particle 204 obtains more negative charges from the charging device 400 and presents a net charge that is electronegative, the net charge property of the electrostatic adsorption layer 504 of the cleaning element 500 should be positive to generate an electrostatic attraction. force. vice versa.

The electrostatic adsorption layer can be a coating, and coating process parameters, such as coating material and coating thickness, may also affect the potential difference between the electrostatic adsorption layer and the particles 204 . For example, in some embodiments, a potential difference between an uncoated silicon wafer and particles 204 having a net charge of about 0.08 volts to about 0.12 volts can be generated; A potential difference of about 0.5 volts to 0.7 volts can be generated between the silicon wafer coated with titanium dioxide (TiO ₂ ) to about 45 nm and the particles 204 having a net charge. In contrast, silicon wafers with a titanium dioxide coating having a thickness of about 35 nm to about 45 nm have a better ability (e.g., number of particles, degree of particle attachment) to adsorb particles 204 than uncoated silicon wafers wafer. In addition, the titanium dioxide coating can be charged positively so as to attract the particles 204 with negative charge. Therefore, the potential difference between the cleaning element 500 and the particles 204 with a net charge can be increased by the coating process parameters to generate a driving force that can help the particles 204 move to the cleaning element 500 .

In some embodiments, the coating on the cleaning element 500 may be formed by at least one of the following processes: thermal oxidation, chemical oxidation, chemical vapor deposition (chemical vapor deposition; CVD), including low pressure CVD (low pressure CVD) ; LPCVD), plasma enhanced CVD (plasma enhanced CVD; PECVD), ultra-high vacuum CVD (ultra-high vacuum CVD; UHVCVD), step-down CVD (reduced pressure CVD; RPCVD), atomic layer deposition (atomic layer deposition; ALD ), physical vapor deposition, pulsed laser deposition, sputtering, evaporative deposition, vapor phase epitaxy (VPE), molecular beam epitaxy (MBE), liquid phase epitaxy (liquid phase epitaxy) ; LPE), electroplating, electroless plating, or other applicable techniques.

FIG. 6A shows a simplified front view of step 306 of method 300 . The cleaning element 500 is moved away from the surface 202 of the supporting base 200 , wherein the particles 204 attached to the cleaning element 500 move away from the surface 202 of the supporting base 200 along with the cleaning element 500 . In some embodiments, the wafer transfer robotic arm T carries the cleaning element 500 , and the cleaning element 500 is moved away from the support base 200 by the movement of the wafer transfer robotic arm T. In Figure 6A, the particles 204 remain attached to the electrostatic adsorption layer 504 of the cleaning element 500 due to the electrostatic force of attraction. The cleaning element 500 is kept away from the surface 202 of the support base 200 . The partial enlargement M5 of the dotted box in Fig. 6A is shown in Fig. 6B.

Fig. 6B shows a partially enlarged front view of M5 in Fig. 6A. After the particles 204 are removed, the surface 202 of the support base 200 is free of particles 204, and the surface 202 of the support base 200 is restored to the state of initial electrical neutrality, in other words, the surface 202 of the support base 200 has the same amount of positive charge with the amount of negative charge. In some embodiments, the electrical neutral state of the surface 202 of the support base 200 can be restored by grounding. It should be noted that the charge in the neutral state on the surface 202 of the support seat 200 may come from the first positive charge 206, the first negative charge 208, the second negative charge 406, or charges obtained by other means (not shown) , or a combination of the above.

In some embodiments, other systems or devices not shown in Figures 4A to 6B, such as gas supply systems, exhaust systems, position calibration systems, positioning drive systems, and/or other devices, may be included. .

Step 108 of the flowchart 100 in FIG. 1 can be achieved by another method of removing particles from the surface of the wafer and/or the support seat of the photomask provided by the present disclosure. FIG. 7 is a flowchart illustrating another method 700 for removing particles from surfaces of wafer and/or reticle support seats according to some embodiments of the present disclosure. Each step operation in the method 700 corresponds to FIG. 8 to FIG. 11 respectively. For example, in step 702 of method 700 and shown in FIG. For example, step 703 of method 700 and shown in FIG. For example, as shown in step 704 of method 700 and FIG. 10 , the cleaning element 500 is moved close to the support base 200 so that the particles 204 on the surface 202 of the support base 200 approach the cleaning element 500 and are attracted to the cleaning element 500 . For example, as shown in step 706 and FIG. 11 , the cleaning element 500 is moved away from the support base 200 . Compared with the method 300 in FIG. 3 , the method 700 in FIG. 7 has one more step 703 , except for other steps, the description of the steps in the method 300 can generally be applied.

Referring to FIG. 8 , a simplified front view of step 702 of method 700 is shown: charging device 400 provides charge 402 to surface 202 of support 200 and particles 204 on surface 202 . In FIG. 8, the charging device 400 also includes a transmission system of the mobile charging device 400, a control system for providing the electric charge 402, and/or other devices. To simplify the description, the above-mentioned system or device is not shown in FIG. 8 .

In some embodiments, the charging device 400 moves above the support base 200 , and the manner of providing the charge 402 includes providing the charge 402 to the surface 202 of the support base 200 and the particles 204 on the surface 202 in a manner similar to spraying. In some embodiments, the wafer support pin 205 remains protruding during the charging device 400 spraying the charge 402 . In some embodiments, the spraying cross-sectional area of the charge 402 sprayed by the charging device 400 is equal to or larger than the placement area of the target, such as a wafer, a photomask, or other targets that need to be maintained horizontally, so as to reduce the contamination of the target by particles and/or or alignment issues. Different embodiments of the partial enlargement M3 of the dotted box in Fig. 7 are shown in Fig. 12A and Fig. 13A (discussed later).

Referring to Figure 9, a simplified front view of step 703 of method 700 is shown: charging device 400 provides charge 900 onto cleaning element 500 (e.g., direction 902) such that cleaning element 500 is charged 900 differently from the support base 200 charges 402. In other words, when the charge 402 obtained by the support seat is a positive charge, the charge 900 obtained by the cleaning element 500 is a negative charge. vice versa. In step 703 of the method 700 , the potential difference between the cleaning element 500 and the particles 204 is affected by performing a pretreatment on the cleaning element 500 .

FIG. 10 illustrates a simplified front view of step 704 of method 700 . The cleaning element 500 approaches the support base 200 (eg, direction 506 ), so that the particles 204 on the surface 202 move toward the cleaning element 500 (eg, direction 508 ) and are attracted to the cleaning element 500 . In some embodiments, the wafer transfer robot T carries the cleaning element 500 , and the cleaning element 500 approaches the support base 200 by the movement of the wafer transfer robot T. FIG. 10 includes other systems or devices, such as a cleaning system for removing particles 204 adsorbed on the cleaning element 500 or other suitable devices. For simplicity of illustration, the above systems or devices are not shown in FIG. 10 .

Continuing to refer to FIG. 10, in some embodiments, the area of the cleaning element 500 is substantially the same as the area of the charge sprayed by the charging device 400 in step 702 of the method 700, which means that it is equal to or larger than the placement area of the target object, such as a wafer, light Covers, or other objects that need to be kept level. In some embodiments, the cleaning element 500 moves above the support base 200 to align with the area where the charging device 400 sprays the charge in step 702 . The cleaning element 500 moves toward the support base 200 (eg, direction 506 ) and the cleaning element 500 eventually stops at a position above the surface 202 of the support base 200 . In some embodiments, the cleaning element 500 absorbs the particles 204 on the surface 202 without contacting the surface 202 of the support base 200 and the protruding wafer support pins 205 . In other embodiments, the cleaning element 500 adsorbs the particles 204 on the surface 202 by contacting the surface 202 of the support base 200 and/or the protruding wafer support pins 205 . Different embodiments of the partial enlargement M4 of the dotted box in Fig. 10 are shown in Fig. 12B and Fig. 13B (discussed later).

FIG. 11 illustrates a simplified front view of step 706 of method 700 . The cleaning element 500 is moved away from the surface 202 of the supporting base 200 , wherein the particles 204 attached to the cleaning element 500 move away from the surface 202 of the supporting base 200 along with the cleaning element 500 . In some embodiments, the wafer transfer robotic arm T carries the cleaning element 500 , and the cleaning element 500 is moved away from the support base 200 by the movement of the wafer transfer robotic arm T. In Figure 11, the particles 204 remain attached to the cleaning element 500 due to the electrostatic force of attraction. When the cleaning element 500 is away from the surface 202 of the support base 200 (for example, along the direction 600), the particles 204 follow the cleaning element 500- And away from the surface 202 of the support seat 200 . A partial enlargement of the dotted box in Fig. 11. Different embodiments of M5 are shown in Figs. 12C and 13C (discussed later).

For the above method 700, the charge provided by the charging device 400 can be negative charge or positive charge. Embodiments for different charges can be further illustrated by the partial enlargements M3 , M4 and M5 in FIG. 8 , FIG. 10 , and FIG. 11 .

Referring to Fig. 12A, a partially enlarged M3 front view of Fig. 8 is shown. The charging device 400 provides the third negative charge 1200 (ie, the charge 402 in FIG. 8 ) to the surface 202 of the support base 200 and the particles 204 on the surface 202 . In some embodiments, the third negative charge 1200 moves from the charging device 400 to the surface 202 and the particles 204 of the support base 200 in a direction 1202 . The surface 202 of the support base 200 and the particles 204 each have a first positive charge 206, a first negative charge 208, and a third negative charge 1200, so that the surface 202 of the support base 200 and the particles 204 each have more negative charges than positive charges Therefore, the surface 202 of the support base 200 and the particles 204 have electronegative properties. When the surface 202 of the support base 200 and the particles 204 have the same electronegative properties separately and at the same time, a repulsive electrostatic force is generated between the surface 202 of the support base 200 and the particles 204 on the surface 202 . In some embodiments, an electrostatic force will be exerted on the particle 204 in a direction away from the surface 202 of the support 200 (eg, along the electrostatic force direction 1204 ).

Referring to FIG. 12B, which shows a partial enlarged M4 front view of FIG. 10, after the particle 204 on the surface 202 receives the third negative charge 1200, the particle 204 has more negative charges than positive charges and has a negative charge. Therefore, a cleaning element 500 capable of attracting electronegative charges may be used. In some embodiments, the charge 900 obtained by the cleaning element 500 from the charging device 400 is a positive charge (ie, the third positive charge 1206 ), so that the cleaning element 500 and the particles 204 generate an electrostatic force that attracts each other. In some embodiments, this attractive electrostatic force moves particles 204 toward cleaning element 500 (eg, in direction 1208 ).

Referring to Fig. 12C, a partially enlarged front view of M5 in Fig. 11 is shown. After the particles 204 are removed, there are no particles 204 on the surface 202 of the support base 200, and the surface 202 of the support base 200 returns to a substantially electrically neutral state, in other words, the surface 202 of the support base 200 has the same positive charge. Quantity vs. Negative Charge Quantity. In some embodiments, the substantially electrically neutral state of the surface 202 of the support base 200 can be restored by grounding. It should be noted that the charge on the surface 202 of the support seat 200 may come from the first positive charge 206, the first negative charge 210, the third negative charge 1200, charges obtained in other ways (not shown), or the above-mentioned combination.

Referring to FIG. 13A, another embodiment of the partially enlarged front view of M3 in FIG. 8 is shown. The charging device 400 provides the fourth positive charge 1300 (ie, the charge 402 in FIG. 8 ) to the surface 202 of the support base 200 and the particles 204 on the surface 202 . In some embodiments, the fourth positive charge 1300 moves from the charging device 400 to the surface 202 and the particles 204 of the support base 200 (eg, moves in the direction 1302 ). The surface 202 of the support seat 200 and the particle 204 each have a first positive charge 206, a first negative charge 210, and a fourth positive charge 1300, so that the surface 202 of the support seat 200 and the particle 204 each have more positive charges than negative charges. The amount of charge, that is, the surface 202 of the support base 200 and the particles 204 each have a positive charge. When the surface 202 of the support base 200 and the particles 204 have the same positive charge respectively and at the same time, a repulsive electrostatic force is generated between the surface 202 of the support base 200 and the particles 204 . In some embodiments, an electrostatic force is exerted on the particle 204 in a direction away from the surface 202 of the support 200 (eg, along the electrostatic force direction 1304 ).

Referring to FIG. 13B, another implementation state of the partially enlarged front view of M4 in FIG. 10 is shown. After the particles 204 obtain the fourth positive charge 1300, the number of positive charges is greater than the number of negative charges and has positive electrical properties, so Cleaning elements 500 capable of attracting electropositive charges may be used. In some embodiments, the charge 900 obtained by the cleaning element 500 from the charging device 400 is a negative charge (ie, the fourth negative charge 1306 ), so that the cleaning element 500 and the particles 204 generate an electrostatic force that attracts each other. In some embodiments, this attractive electrostatic force moves particles 204 toward cleaning element 500 (eg, in direction 1308 ).

Referring to Fig. 13C, a partially enlarged front view of M5 in Fig. 11 is shown. After the particles 204 are removed, there are no particles 204 on the surface 202 of the support base 200, and the surface 202 of the support base 200 returns to a substantially neutral state, that is, the surface 202 of the support base 200 has the same amount of positive and negative charges. amount of charge. In some embodiments, the substantially electrically neutral state of the surface 202 of the support base 200 can be restored by grounding. It should be noted that the charge on the surface 202 of the support base 200 may come from the first positive charge 206, the first negative charge 210, the fourth positive charge 1300, charges obtained in other ways (not shown), or the above-mentioned combination.

There may be other process operations between the operation steps of method 300 and method 700 , which may be omitted for the purpose of simplifying the description. Furthermore, the method 300 and the method 700 are merely examples, and are not intended to limit the present disclosure to what is expressly stated in the claims.

In some embodiments, the steps 302 - 306 in the method 300 and the steps 702 - 306 in the method 700 may be continuously repeated to remove the particles 204 on the surface 202 of the support base 200 . After the support base 200 is cleaned, the step 110 in FIG. 1 can be continued.

Figure 14 schematically illustrates a lithography apparatus 1400 having a support base, according to some embodiments of the present disclosure. The components of the lithography equipment 1400 include a light source system 1406 for adjusting the radiation beam B (for example, extreme ultraviolet (extreme ultraviolet, EUV)), a photomask M and a photomask stage 1408 supporting the photomask M, wherein the photomask stage 1408 Connected to the mask positioning transmission element 1410, the mask positioning transmission element 1410 can position the mask M accurately. The lithography equipment 1400 also includes a wafer stage 1414 for holding the wafer W, and the wafer stage 1414 is connected to the wafer positioning transmission element 1416 . The wafer positioning transmission element 1416 can accurately position the wafer W. The wafer stage 1414 acts as a support seat because it supports the wafer W. The lithography equipment 1400 further includes a projection system (eg, a refractive projection lens system) 1412 for projecting the pattern of the radiation beam B through the mask M onto the target position of the wafer W.

In some embodiments, light source system 1406 may include various types of optical components for directing, shaping, or steering radiation beam B, such as refractive, reflective, magnetic, electromagnetic, electrostatic, or other types of optical components , or any combination thereof.

The photomask stage 1408 is used as a supporting seat, which can support the photomask M (ie, carry its weight). In some embodiments, the reticle stage 1408 can hold the reticle M using mechanical, vacuum, electrostatic or other clamping techniques. The reticle stage 1408 may secure the reticle M in a desired position, eg, relative to the projection system 1412 .

In some embodiments, the mask M is any element that can be used to pattern a radiation beam in order to form a pattern in the wafer W. It should be noted that the pattern formed in radiation beam B must correspond exactly to the desired pattern in wafer W when the pattern includes phase shifting features. In general, the patterns formed in the radiation beam B will correspond to specific functional layers of the components to be formed in the wafer W, such as integrated circuits.

In some embodiments, projection system 1412 is any type of projection system, including refractive, reflective, catadioptric, magnetic, Electromagnetic and electrostatic optical systems or any combination thereof.

Lithography apparatus 1400 may have two or more wafer stages and/or two or more mask stages, which is referred to as a "multi-stage" type of mechanism. In this multi-stage setup, additional stages may be used in parallel, or preparatory steps may be performed on one or more stages or supports while one or more other stages or supports are used for the exposure process.

The lithography apparatus 1400 may also be of a type in which at least part of the wafer W may be covered by a liquid having a relatively high refractive index (eg, water) in order to fill the space between the projection system 1412 and the wafer W. Immersion technology can increase the numerical aperture (numerical aperture, NA) of the projection system. The term "immersion" used in the foregoing does not mean that the wafer W is necessarily submerged in the liquid, but only means that the liquid is located between the projection system 1412 and the wafer W during exposure.

Light source system 1406 in FIG. 14 receives radiation beam B from radiation source 1402 . After the radiation beam B is generated from the radiation source 1402, the radiation beam B is transmitted to the light source system 1406 with the help of the delivery system 1404, wherein the delivery system 1404 includes a suitable guide mirror and/or a beam amplifier. In some embodiments, radiation source 1402, delivery system 1404, and light source system 1406 may collectively be referred to as a radiation system.

In some embodiments, the light source system 1406 may further include an adjuster 1418 for adjusting the angular light intensity distribution of the radiation beam B. Additionally, light source system 1406 may include various other components, such as light integrator 1420 and light concentrator 1422 . The light source system 1406 can be used to adjust the radiation beam B to achieve a desired uniformity and intensity distribution of light.

The radiation beam B is incident on the mask M fixed on the mask positioning transmission element 1410 , and a pattern is generated by the mask M. After passing through the reticle M, the radiation beam B will pass through the projection system 1412 . Projection system 1412 may focus beam of radiation B onto a target location in wafer W placed on wafer stage 1414 . By means of the wafer positioning drive element 1416, the wafer stage 1414 can be moved accurately in order to position different target positions in the wafer W into the path of the radiation beam B. Likewise, the reticle stage 1408 can be accurately moved to position the reticle M relative to the path of the radiation beam B by means of the reticle positioning actuator 1410 . Generally, the movement of the mask stage 1408 can be realized by means of a part of the long-stroke module (for rough positioning) and the short-stroke module (for precise positioning) in the mask positioning transmission element 1410 . Likewise, the movement of the wafer stage 1414 can also be achieved using the wafer positioning transmission element 1416 . In some embodiments, in the case of a stepper, the reticle stage 1408 may only be connected to a short-stroke actuator, or be fixed. The mask alignment marks on the mask M and the wafer alignment marks on the wafer W can be used to align the mask M on the mask stage 1408 and the wafer W on the wafer stage 1414 .

When the photomask carrier 1408 and/or wafer carrier 1414 in the lithography equipment 1400 change different types of wafers/masks (such as step 102 in the first figure), perform periodic maintenance of the equipment (such as the step in the first figure 104), or perform equipment maintenance (such as step 106 in FIG. 1), according to some embodiments of the present disclosure, such as method 300 in FIG. 3 or method 700 in FIG. And/or a particle removal cleaning step of the wafer stage 1414 (such as step 108 in FIG. 1 ). After removing the particles on the photomask stage 1408 and/or the wafer stage 1414, the target wafer and/or the photomask are placed on the workbench for lithography process (such as step 110 in FIG. 1 ).

In some embodiments, see FIG. 15 , prior to performing particle removal cleaning of wafer stage 1414 using method 300 or method 700 , wafer W is loaded and unloaded from wafer stage 1414 using wafer positioning actuator 1416 Wafer stage 1414 is moved out of range of projection system 1412 (eg, in direction 1500 ) and positioned under charging apparatus 400 . In some embodiments, after the charging apparatus 400 provides electrical charge to the surface of the wafer stage 1414 (such as step 302 of the method 300), the wafer stage 1414 remains in place (i.e., out of range of the projection system 1412), and the cleaning element is then moved. Approaching the wafer stage 1414 (eg, step 304 of method 300 ) and moving the cleaning element away from the wafer stage 1414 (eg, step 306 of method 300 ). After the above steps of cleaning the wafer stage 1414 are completed, the wafer positioning transmission element 1416 is used to move the wafer stage 1414 back to the range of the projection system 1412 to perform the lithography process. In some other embodiments, after the charging device 400 provides charges to the surface of the wafer stage 1414 (such as step 302 of the method 300), the wafer positioning transmission element 1416 is used to move the wafer stage 1414 back to the range of the projection system 1412 Inside, move the cleaning element close to the wafer stage 1414 (such as step 304 of the method 300) and move the cleaning element away from the wafer stage 1414 (such as step 306 of the method 300). After the above steps of cleaning the wafer stage 1414 are completed, the lithography process can be performed.

Based on the above description, the present disclosure provides a method for removing particles from a wafer support or a photomask support. The charge is provided by a charging device to generate repulsive static electricity between the support and the particles on the support. Force, and then make the particles on the support seat and the cleaning element generate an electrostatic force of attraction, so as to maintain the interference from particles during the process, test and analysis. In addition, the non-contact cleaning by electrostatic force can reduce the damage to the supporting base compared with the contact cleaning.

In some embodiments of the present disclosure, a method of removing particles includes providing a charge to a surface of a support and to particles on the surface, moving a cleaning element closer to the surface, and moving the cleaning element away from the surface. Providing charges on the surface of the support base and the particles on the surface can make the surface of the support base and the particles on the surface have the same negative charge. The cleaning element has an electrostatic adsorption layer, so that the particles with electronegative electricity move toward the cleaning element and are adsorbed on the electrostatic adsorption layer. In some embodiments, the provided charge comprises electrons, ions, or plasma. In some embodiments, the cleaning elements do not physically contact the surface of the support seat. In some embodiments, the electrostatic adsorption layer of the cleaning element is an inherently electropositive titanium dioxide coating.

In other embodiments of the present disclosure, a method of removing particles includes moving a charging device onto a surface of a support, the charging device providing a first charge to the surface and at least one particle on the surface, and the charging device providing a second charge. A charge is applied to the cleaning elements, the cleaning elements are moved closer to the surface, and the cleaning elements are moved away from the surface. The charging device provides a first charge to impart a first electrical property to the surface and particles on the surface, and a second electrical charge to impart a second electrical property to the cleaning element different from the first electrical property. The cleaning element having the second electrical property moves the particles having the first electrical property toward and adsorbs on the cleaning element. In some embodiments, the surface returns to electrical neutrality after the cleaning element is removed from the surface.

According to other embodiments of the present disclosure, a method for removing particles includes moving a charging device onto a surface of a support, charging the device to provide charges to the particles on the surface, preparing a substrate, placing an electrostatic adsorption layer on the substrate, by The surface of the substrate relatively close to the support seat is moved by the transfer robot arm, the particles on the surface are adsorbed to the electrostatic adsorption layer, and the surface of the substrate relatively far away from the support seat is moved by the transfer robot arm. The charging device provides charges to the particles on the surface so that the particles have a first potential. The substrate has a second potential, wherein there is a first potential difference between the second potential and the first potential. The electrostatic adsorption layer has a third potential, wherein there is a second potential difference between the third potential and the first potential, and the second potential difference is greater than the first potential difference. In some embodiments, the charging device includes an electron gun, an ion generator, or a plasma generator. In some embodiments, the electrostatic adsorption layer is a titanium dioxide coating. In some embodiments, the substrate is a silicon wafer.

The foregoing summarizes features of several embodiments so that those skilled in the art may better understand aspects of the disclosure. Those skilled in the art should understand that they can readily use the present disclosure as a basis for designing or modifying other processes and structures to achieve the same purpose and/or achieve the same advantages of the embodiments described herein. Those skilled in the art should also understand that such equivalent configurations do not depart from the spirit and scope of the disclosure, and those with ordinary knowledge in the art can make Various alterations, substitutions, and alterations have been made herein.

100: Flowchart 102, 104, 106, 108, 110: steps 200: support seat 200': Support seat 202: surface 204: Particles 205: Wafer support pin 206: First positive charge 208: The first negative charge 300: method 302, 304, 306: steps 400: charging device 402: charge 404: direction 406: The second negative charge 408: direction 410: Electrostatic Force Direction 500: cleaning element 502: Substrate 504: electrostatic adsorption layer 506: direction 508: direction 510: second positive charge 600: direction 700: method 702, 703, 704, 706: steps 900: charge 902: direction 1200: The third negative charge 1202: direction 1204: Electrostatic force direction 1206: The third positive charge 1208: direction 1300: The fourth positive charge 1302: direction 1304: Electrostatic force direction 1306: The fourth negative charge 1308: direction 1400: Lithography equipment 1402: Radiation source 1404: delivery system 1406: Light source system 1408: Mask carrier 1410: Reticle positioning drive element 1412:Projection system 1414: wafer carrier 1416: Wafer positioning drive element 1418:Adjuster 1420: light integrator 1422: Concentrator 1500: Direction B: radiation beam M: mask M1, M2, M3, M4, M5: partial enlargement T: Teleport Robotic Arm W: Wafer

When reading the following implementation methods with accompanying drawings, the viewpoints of the disclosure can be clearly understood. It should be noted that, in accordance with the standard practice in the industry, various features are not drawn to scale. In fact, the dimensions of the various features may be arbitrarily expanded or reduced for clarity of discussion. FIG. 1 shows a flow chart for determining the timing of cleaning a wafer and/or a mask support according to some embodiments of the present disclosure. Figures 2A and 2C show front views of support bases and particles according to some embodiments of the present disclosure. Figures 2B and 2D are partially enlarged front views of Figures 2A and 2C, respectively. FIG. 3 illustrates a flow diagram of a method of removing particles from surfaces of wafer and/or reticle support seats according to some embodiments of the present disclosure. FIG. 4A illustrates a front view of one step in a method of removing particles, according to some embodiments of the present disclosure. Figure 4B is a partially enlarged front view of Figure 4A. FIG. 5A illustrates a front view of one step in a method of removing particles, according to some embodiments of the present disclosure. Figure 5B is a partially enlarged front view of Figure 5A. FIG. 6A illustrates a front view of one step in a method of removing particles, according to some embodiments of the present disclosure. Figure 6B is a partially enlarged front view of Figure 6A. FIG. 7 illustrates a flow diagram of a method of removing particles from the surface of a support seat of a wafer and/or a reticle, according to some embodiments of the present disclosure. FIG. 8 illustrates a front view of one step in a method of removing particles according to some embodiments of the present disclosure. FIG. 9 illustrates a front view of one step in a method of removing particles, according to some embodiments of the present disclosure. FIG. 10 illustrates a front view of one step in a method of removing particles, according to some embodiments of the present disclosure. FIG. 11 illustrates a front view of one step in a method of removing particles, according to some embodiments of the present disclosure. Fig. 12A is a partially enlarged front view of an embodiment of Fig. 8 . Fig. 12B is a partially enlarged front view of an embodiment in Fig. 10 . Fig. 12C is a partially enlarged front view of the embodiment in Fig. 11. Fig. 13A is a partially enlarged front view of another embodiment of Fig. 8 . Fig. 13B is a partially enlarged front view of another embodiment of Fig. 10 . Fig. 13C is a partially enlarged front view of another embodiment of Fig. 11. FIG. 14 illustrates a lithography apparatus according to some embodiments of the present disclosure. FIG. 15 illustrates a lithography apparatus according to some embodiments of the present disclosure.

Domestic deposit information (please note in order of depositor, date, and number) none Overseas storage information (please note in order of storage country, institution, date, and number) none

108: Step

300: method

302: Step

304: step

306: Step

Claims (10)

A method of removing particles, comprising: providing an electric charge onto a surface of a support base and a particle on the surface in a manner of spraying an electric charge, so that the surface and the particle on the surface have the same a Negative charge; move a cleaning element close to the surface, wherein the cleaning element is aligned with the area where the charge is sprayed, wherein the cleaning element has an electrostatic adsorption layer, and the electrostatic adsorption layer is a titanium dioxide coating with positive charge, so that The particles having the electronegative charge move toward the cleaning element and adsorb on the electrostatic adsorption layer of the cleaning element; and move the cleaning element away from the surface. The method for removing particles as claimed in claim 1, wherein providing the charge includes providing electrons, ions, or plasma. The method for removing particles as claimed in claim 1, wherein the cleaning element does not physically contact the surface of the support base. The method for removing particles as claimed in claim 1, wherein the thickness of the titanium dioxide coating is 35 nm to 45 nm. A method of removing particles, comprising: moving a charging device onto a surface of a support; the charging device provides a negative charge to the surface and at least one of the surface On a particle, the surface and the at least one particle on the surface are negatively charged; the charging device provides a positive charge to a cleaning element in the form of a spray charge, the cleaning element has an electrostatic adsorption layer, and the electrostatic adsorption The layer is a titanium dioxide coating with positive charge, which makes the cleaning element positive, wherein the cleaning element is aligned with the area where the charge is sprayed; moving the cleaning element close to the surface, wherein the positive cleaning element moving the at least one negatively charged particle toward the cleaning element and adsorbing on the electrostatic adsorption layer of the cleaning element; and moving the cleaning element away from the surface. The method for removing particles as claimed in claim 5, wherein after the cleaning element moves away from the surface, the surface returns to electrical neutrality. A method for removing particles, comprising: moving a charging device onto a surface of a support base; the charging device provides a charge to a particle on the surface in a manner of spraying charges, so that the particle has a first potential , wherein in the process of spraying electric charges, a plurality of wafer support pins of the support stand are kept in a protruding state; a substrate is prepared, and the substrate has a second potential, wherein the difference between the second potential and the first potential There is a first potential difference between them; an electrostatic adsorption layer is set on the substrate, the electrostatic adsorption layer is a titanium dioxide coating with positive charge, so that the electrostatic adsorption layer has a third potential, wherein there is a second potential difference between the third potential and the first potential, and the second potential difference is greater than the first potential difference; moving the substrate relatively close to the surface of the support seat by a transport robot arm; The particles on the surface are adsorbed to the electrostatic adsorption layer; and the substrate is moved relatively away from the surface of the supporting base by the conveying robot arm. The method for removing particles according to claim 7, wherein the charging device includes an electron gun, an ion generator, or a plasma generator. The method for removing particles according to claim 7, wherein the electrostatic adsorption layer has a thickness of 35 nm to 45 nm. The method for removing particles as claimed in claim 7, wherein the substrate is a silicon wafer.

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