Polishing system, polishing method, and method for chemical mechanical polishing

Abstract

A system and method for a chemical mechanical polishing (CMP) process on a substrate is described. The CMP process planarizes a portion of a material layer on the substrate and selectively polishes another portion of the material layer within a predetermined distance from a stop layer. The system includes a polishing pad on a rotating platen and a dispenser to dispense an abrasive solution and an additive solution on the polishing pad. The abrasive solution and the additive solution are combined on the polishing pad to form a slurry that is used to perform the CMP process on the substrate.

Description

Technical Field

[0001] This disclosure relates to a method for chemical mechanical polishing, a polishing method, and a polishing system. Background Technology

[0002] Polishing semiconductor wafers using a chemical mechanical planarization (CMP) system involves preparing a slurry by diluting and blending an abrasive component and an additive component. The additive and abrasive components of the CMP slurry can be blended at various stages of the CMP process. The stage at which the slurry is prepared can affect its functionality and quality. Summary of the Invention

[0003] According to some embodiments of this disclosure, a method for chemical mechanical polishing is provided, comprising: mixing an abrasive solution and an additive solution to form a slurry on a rotating polishing pad; contacting a substrate with the slurry on the polishing pad, wherein the substrate is held and rotated by a substrate carrier; polishing an exposed layer on the substrate using the slurry, the polishing comprising: monitoring a current, voltage, or torque measurement representing a material composition of the exposed layer; determining a change in the current, voltage, or torque measurement due to a change in the material composition of the exposed layer; and changing a first flow rate of the abrasive solution and a second flow rate of the additive solution based on the change in the current, voltage, or torque measurement; and cleaning the substrate after polishing.

[0004] According to some embodiments of this disclosure, a polishing method is provided, comprising: chemically and mechanically polishing a material layer on a substrate using a first slurry formed from an abrasive solution and an additive solution; measuring a polished height of the material layer; switching from the first slurry to a second slurry formed from the abrasive solution and the additive solution in response to the polished height being within a predetermined distance from a stop layer on the substrate, wherein the second slurry provides a higher material selectivity than the first slurry; and chemically and mechanically polishing the material layer using the second slurry.

[0005] According to some embodiments of this disclosure, a polishing system is provided, comprising: a polishing pad configured to rotate on a platform; a substrate carrier configured to hold a substrate above and in contact with the polishing pad; and a dispenser comprising: a first nozzle configured to dispense an abrasive solution onto the polishing pad; and a second nozzle configured to dispense an additive solution onto the polishing pad to mix with the abrasive solution to form a slurry. Attached Figure Description

[0006] The nature of this disclosure can be best understood from the following detailed description when read in conjunction with the accompanying drawings. It should be noted that, according to common industry practice, the various features are not drawn to scale. In fact, for clarity of explanation, the dimensions of the various features may be arbitrarily increased or decreased.

[0007] Figure 1 A schematic diagram of a polishing system according to one of some embodiments is shown.

[0008] Figure 2 Examples illustrate the pH variations of three different slurries according to some embodiments.

[0009] Figure 3 The particle size distribution of the abrasive components in three different slurries according to some embodiments is illustrated.

[0010] Figures 4A-4D A cross-sectional view of a polishing tool for performing a chemical mechanical polishing (CMP) procedure, according to some embodiments, is shown.

[0011] Figure 5 This section illustrates a method of operating a CMP system according to some embodiments.

[0012] Figures 6A-6E A cross-sectional view of a CMP system illustrating a method for operating a CMP system according to some embodiments.

[0013] Figure 7 This example illustrates step height data collected by a detection device according to some embodiments.

[0014] Figure 8A An example of a method of operating a polishing system according to some embodiments is given to perform a CMP procedure on a substrate having an oxide layer.

[0015] Figure 8B-8D This illustration shows a cross-sectional view of a partially manufactured substrate undergoing a CMP process, according to some embodiments.

[0016] Figure 9 An example is given of a variation in oxide removal rate relative to pressure according to some embodiments.

[0017] Figure 10A Examples include current, voltage, or platform torque signals collected by a detection device according to some embodiments.

[0018] Figure 10B and 10C Examples are shown of oxide loss data measured during a CMP procedure according to some embodiments.

[0019] Figure 11AAn example of a method of operating a polishing system according to some embodiments is given to perform a CMP procedure on a substrate having a silicon nitride layer.

[0020] Figure 11B-11D This illustration shows a cross-sectional view of a partially manufactured substrate undergoing a CMP process, according to some embodiments.

[0021] Figure 12A Examples include current, voltage, or platform torque signals collected by a detection device according to some embodiments.

[0022] Figure 12B and 12C Examples of silicon nitride loss data measured during a CMP procedure according to some embodiments are shown.

[0023] Figure 13 An example is given of a variation in the removal rate relative to the concentration of the abrasive component, according to some embodiments.

[0024] Figure 14 An example of a high-level block diagram of a computer system according to one of some embodiments is shown. Detailed Implementation

[0025] The following disclosure provides numerous different embodiments or examples for implementing various features of the provided subject matter. Specific examples of components and configurations are described below to simplify this disclosure. Of course, these are merely examples and are not intended to be limiting. For instance, in the following description, forming a first feature over a second feature may include embodiments where the first and second features are formed in direct contact, and may also include embodiments where an additional feature may be formed between the first and second features so that the first and second features are not in direct contact.

[0026] Additionally, for ease of explanation, this document may use spatial relative terms such as “under,” “below,” “below,” “above,” “on top,” and similar terms to describe the relationship of one element or feature relative to another element(s) as illustrated in the accompanying drawings. Besides the orientations shown in the drawings, the spatial relative terms are intended to cover different orientations of the device in use or operation. The device may be oriented in other ways (rotated 90 degrees or in other orientations) and the spatial relative terms used herein may be interpreted accordingly.

[0027] The term “about” as used in this document refers to a given value that can vary based on a particular technology node associated with the subject semiconductor device. In some embodiments, based on that particular technology node, the term “about” may refer to a value of a given amount that varies, for example, within the range of 5–30% (e.g., ±5%, ±10%, ±20%, or ±30%).

[0028] Chemical mechanical planarization (CMP) (also referred to herein as "chemical mechanical polishing" or "polishing") is a planarization technique used to planarize the surface of a substrate by means of a relative movement between a substrate and a polishing pad in the presence of a slurry. During the CMP process, a downward pressure is applied to the substrate. In a CMP system, the substrate (also referred to herein as a "wafer") is positioned face down on a wafer holder or substrate carrier and held against a polishing pad positioned on a flat surface (also referred to herein as a "platform"). A slurry is dispensed onto the polishing pad. The polishing machine may use a rotary or orbital motion during the polishing process. The CMP process achieves substrate planarity by removing protrusions relative to recessed features on the surface of the substrate.

[0029] A CMP process may have several stages, such as removing an initial elevation of a material layer (also referred to in this case as a "planarization operation") and a selective polishing operation for the CMP process to stop at another material layer. These stages may require different slurry compositions to avoid over- or under-polishing different areas on the substrate. The slurry is a mixture of an abrasive solution and an additive solution. The abrasive solution in the slurry removes a material layer from the substrate using mechanical abrasion. The abrasive solution plays a dominant role in the main part of removing the material layer; or in other words, it plays a role in planarizing the surface of the substrate in a chemical-physical manner due to a chemical-physical abrasion process occurring between the abrasive solution and the substrate. On the other hand, the additive solution in the slurry physically protects the stop layer material from the surface of the substrate by surface adsorption between the additive solution and the material layer on the surface of the substrate. Therefore, the additive solution forming the slurry enables the CMP process to selectively stop at another material layer (also referred to in this case as a "stop layer") on the wafer surface.

[0030] Before dispensing the slurry onto the wafer during a CMP process, the slurry can be prepared in a mixing tank. Slurry preparation may include (a) diluting an abrasive component in deionized (DI) water to form an abrasive solution, (b) diluting an additive component in the DI water to form an additive solution, and (c) mixing the abrasive solution and the additive solution to form the slurry. Using a premixed slurry can present challenges in achieving an optimal material removal rate. The abrasive component in the slurry includes nano-sized abrasive particles. One of the first challenges arising from using a premixed slurry is that, over time, the suspended nano-sized particles, along with the additive component, may agglomerate in the slurry solution to form larger particles. Agglomeration affects (a) the pH of the slurry and (b) the material removal rate due to the larger particle size. A slurry with a pH between approximately 4.0 and approximately 5.0 can provide an optimal removal rate. Abrasive solutions with a pH greater than 5 are unstable. When abrasive solutions and additive solutions are mixed to form a slurry, the pH of the slurry increases. This increase in pH leads to an increase in the amount of H+ in the slurry. + A decrease in ions increases the zeta potential of the slurry. This increased zeta potential reduces the repulsive effect between cerium hydroxide (Ce(OH)4) particles, promoting agglomeration. Therefore, the increased pH causes the abrasive component (Ce(OH)4) to agglomerate. Agglomeration produces larger abrasive particles, reducing the overall surface area of ​​the abrasive component in contact with the polished wafer surface. This reduces the polishing rate of the CMP process.

[0031] A second challenge in using premixed slurries is maintaining a consistent slurry composition throughout all stages of the CMP process. For example, the slurry used to planarize the bulk of the material layer will also be used to polish wafer regions requiring greater material selectivity. This can lead to underpolishing of material layers requiring a more abrasive CMP process and overpolishing of material layers requiring greater material selectivity. Therefore, a fixed slurry composition does not provide the flexibility to optimize the performance of a CMP process by polishing material layers at various stages.

[0032] This disclosure provides a CMP system and method in which slurry performance—which depends on the mixing ratio of one of the abrasive solution and the additive solution—can be optimized by controlling the flow rates of the abrasive solution and the additive solution. In the disclosed CMP system and method, the abrasive solution and the additive solution are dispensed onto a polishing pad via two separate nozzles and mixed on the polishing pad to form a slurry. The concentration or mixing ratio of the abrasive solution and the additive solution can be adjusted while an overall flow rate remains substantially constant. Furthermore, since the abrasive solution and the additive solution are not premixed to form the slurry, agglomeration of abrasive particles can be suppressed to avoid the formation of larger abrasive particles. Due to a larger contact area between the abrasive particles and the matrix, smaller abrasive component particles provide a higher polishing rate. In addition, not mixing the abrasive solution and the additive solution avoids (a) temperature variations in slurries with different mixing ratios and (b) volume variations in the slurry due to temperature variations during the mixing process of the abrasive solution and the additive solution. One benefit of this disclosure is, in particular, a CMP system and method that uses a single platform and a single abrasive solution to provide an optimized CMP procedure for CMPing different dielectric layers. An optimized CMP procedure refers to a CMP procedure that can be modified to be effectively used for: (a) a planarization operation, which is a physically abrasive polishing procedure, and (b) a selective polishing operation, which is a chemical procedure, wherein an additive solution (e.g., a chemically reactive component) selectively reacts with the material layer, while the abrasive component mechanically removes the material layer. During the planarization operation, the material layer can be removed primarily by chemical-physical abrasion. On the other hand, during the selective polishing operation, the material layer can be removed primarily by chemical-physical abrasion, while the stop layer can be protected primarily by a surface adsorption.

[0033] Figure 1 This is a schematic diagram of a CMP system 100 according to some embodiments of the present disclosure. Figure 1As illustrated, the CMP system 100 may include a polishing pad 103 mounted on a rotary platform (e.g., a rotary table) 102. The CMP system 100 may also include a substrate carrier 104 rotatably holding a substrate 105, a rotary adjustment wheel (or "disk", "adjustment disk") 106, and a distributor 110 fluidly connected to an abrasive solution mixing tank 120 and an additive solution mixing tank 122. The CMP system 100 also includes a computer system 108, wherein the various components of the CMP system can be configured to communicate with the computer system 108 via communication links. In some embodiments, the rotary platform 102 may communicate with the computer system 108 via communication link 118. The disk 106 and the substrate carrier 104 may communicate with the computer system 108 via communication links 114 and 116, respectively. Similarly, in some embodiments, the abrasive solution mixing tank 120 and the additive solution mixing tank 122 may communicate with the computer system 108 via communication links 126 and 124, respectively. For illustrative purposes, Figure 1 The system includes selected portions of the CMP system 100 and may include other portions (not shown), such as control units, transfer devices, pumps, and discharge ports. In some embodiments, communication links 114, 116, 118, 124, and 126 may be a wired or wireless link.

[0034] In some embodiments, the CMP system 100 may include separate mixing tanks for forming abrasive solutions and additive solutions. For example, see reference... Figure 1 As described, the CMP system 100 includes an abrasive solution mixing tank 120 with a first stirrer 120a. An abrasive component, including nanoscale abrasive particles, can be diluted in DI water within the abrasive solution mixing tank 120. A feeder 120b supplies the abrasive solution to a distributor 110. The system also includes an additive solution mixing tank 122 with a second stirrer 122a. An additive component—which may be a chemically reactive species—can be diluted in DI water within the additive solution mixing tank 122. The feeder 122b supplies the additive solution to the distributor 110. Stirrers 120a and 122a may include a fan in the abrasive solution 112a and additive solution 112b, and a bearing supporting the fan. The bearing may be coupled to a motion mechanism (not shown), such as a pump or a motor, to rotate the fan. In some embodiments, stirrers 120a and 122a may be ultrasonic devices or oscillator devices.

[0035] In some embodiments, the dispenser may include separate nozzles for dispensing abrasive solution and additive solution onto the wafer. For example, see reference... Figure 1As described, the dispenser 110 may include a nozzle 110a for dispensing the abrasive solution 112a and a nozzle 110b for dispensing the additive solution 112b. The nozzles 110a and 110b may be connected to flow controllers (not shown) capable of controlling the flow rates of the abrasive solution 112a and the additive solution 112b flowing through the nozzles 110a and 110b, respectively. The abrasive solution 112a and the additive solution 112b may be mixed on the polishing pad 103 to form a slurry. The flow controllers and flow rates of the abrasive solution and the additive solution may be controlled by a computer system 108.

[0036] In some embodiments, the abrasive component of the abrasive solution 112a may be one or more of silicon dioxide (SiO2), aluminum oxide (Al2O3), cerium dioxide (CeO2), cerium hydroxide (Ce(OH)4), carbon (C), silicon carbide (SiC), or titanium dioxide (TiO2). Depending on the substrate polishing application, one or more abrasive components may include particles of SiO2, CeO2, Al2O3, zirconium oxide (ZrO2), TiO2, iron oxide (Fe2O3), zinc oxide (ZnO), or any other suitable material.

[0037] Polishing pad 103 is attached to a top surface of rotary platform 102. Due to the mechanical properties and porosity of polyurethane, polishing pad 103 may be made of polyurethane, for example. Furthermore, polishing pad 103 may include small perforations to help deliver the slurry along the wafer surface and promote uniform polishing. Polishing pad 103 also removes reacted products from the wafer surface. As polishing pad 103 polishes more wafers, the surface of the polishing pad becomes flat and smooth, resulting in a condition known as "glazing." Glazed polishing pads cannot retain slurry—significantly reducing the polishing rate.

[0038] The substrate 105 to be polished (also referred to as "wafer 105" in this case) is mounted face down at the bottom of the substrate carrier 104, such that the top surface of the substrate contacts the top surface of the polishing pad 103. The substrate carrier 104 rotates the substrate 105 and applies pressure (e.g., a low pressure) thereon, causing the substrate 105 to press against the polishing pad 103. An abrasive solution 112a and an additive solution 112b may be dispensed onto the surface of the polishing pad, where they are mixed to form a slurry. Depending on a mixing ratio or flow rate of the abrasive solution 112a and the additive solution 112b, the slurry formed on the polishing pad may be more mechanically abrasive or more chemically reactive. The chemical reaction and mechanical abrasion in the slurry, substrate 105, and polishing pad 103 may cause material to be removed from the top surface of the substrate 105. Simultaneously, an adjusting disc 106 may agitate the top surface of the polishing pad 103 to restore its roughness. However, this is not a limitation; the adjusting disc 106 can adjust the polishing pad 103 after the substrate 105 has been polished and removed from the CMP system 100.

[0039] Polishing pad 103 requires periodic adjustment to delay the smoothing effect. The purpose of adjustment is to remove old slurry particles and worn particles from the polishing pad, thereby extending its lifespan and providing consistent polishing performance throughout its lifespan. The polishing pad can be adjusted by mechanical abrasion or by a deionized (DI) water jet, which agitates (activates) the surface of the pad and increases its roughness. One alternative method for activating the surface of the pad is to use an adjustment disc 106, characterized by a bottom diamond surface that contacts the polishing pad 103 as it rotates.

[0040] The pH of the premixed slurry solution can change over time, which can affect the polishing rate or material removal rate. For example, Figure 2 The pH of the first, second, and third slurries is shown as a function of time. Curve 202 represents the pH of a first slurry solution prepared by: (a) a first operation involving blending an additive component with DI water to form an additive solution containing DI water having a specific pH (e.g., about 7.9); and (b) a second operation involving adding a 1% abrasive solution having another pH (e.g., about 4.4) to the additive solution to form the first slurry having an additive component, DI water, and an abrasive component in a ratio of 2:17:1. As an example, the abrasive component may be cerium hydroxide (Ce(OH)4). As shown in curve 202, the pH of the first slurry can change rapidly over time during a dilution phase and may, for example, suddenly increase to about 7.8 at a certain time. During the storage phase, the pH of the first slurry remains substantially constant, as... Figure 2 As shown. Figure 3This demonstrates the change in the mass percentage of the abrasive component in the slurry due to agglomeration, which increases the particle size (particle size distribution). For example, by... Figure 3 As shown in curve 302, the pH of the first slurry increases due to the aggregation of a larger number of Ce(OH)4 particles into large Ce(OH)4 particle clusters. As explained above, an increase in slurry pH can be accompanied by a decrease in Zeta potential. A first slurry with a pH of about 6.7 may, for example, have a Zeta potential of about 21 mV. A low Zeta potential promotes aggregation.

[0041] Figure 2 Curve 204 represents a second slurry prepared by: (a) a first operation involving blending an abrasive component (e.g., about 0.06% by weight) with DI water to form an abrasive solution having a specific pH (e.g., about 4.1); and (b) a second operation involving adding an additive component having another pH (e.g., about 8.0) to the abrasive solution to form the second slurry having an abrasive component, DI water, and an additive component in a ratio of 1:17:2. As shown by curve 204, the pH of this second slurry can change smoothly over time during the dilution phase and can gradually increase to, for example, about 7.8. During the storage phase, the pH of the first slurry remains substantially constant, as... Figure 2 As shown. Similar to the first slurry, due to... Figure 3 As shown in curve 304, a large number of Ce(OH)4 particles agglomerate to form large Ce(OH)4 particle clusters, and the pH of the second slurry also increases over time. Based on the above, the pH of the first and second slurries increases over time to, for example, about 7.8, which is outside the pH range required for optimal slurry performance and removal rate.

[0042] This disclosure reveals a third slurry that remains stable over time, unlike the first and second slurries mentioned above, which agglomerate over time. Figure 2 Curve 206 represents a third slurry prepared by: (a) blending an abrasive component (e.g., about 0.1% by weight) in DI water to form an abrasive solution having a specific pH (e.g., about 4.2); (b) blending an additive component in DI water to form an additive solution having a specific pH (e.g., about 8); and (c) mixing the abrasive solution and the additive solution on a polishing pad to form the third slurry. As shown in curve 206, according to some embodiments, the pH of the third slurry can remain stable between about 4.0 and about 5.0 during the dilution and storage phases. Figure 3As shown in curve 306, the abrasive component particles, such as Ce(OH)4, exhibit the least agglomeration in the third slurry solution compared to the first and second slurries. Since the pH of the third slurry is stable, a third slurry with a pH of approximately 4.0 can, for example, have a Zeta potential of approximately 68 mV. In some embodiments, because the abrasive solution and additive solution are mixed on the polishing pad, agglomeration in the third slurry is suppressed. Therefore, the abrasive component in the third slurry can have a larger surface area of ​​the wafer that can be accessed and polished compared to the abrasive components in the first and second slurries.

[0043] Furthermore, the abrasive particle aggregation in the slurry also affects the removal rate due to variations in particle size and number. Smaller abrasive particles can have a larger surface area for contacting and grinding the wafer, resulting in a higher removal rate. On the other hand, a large agglomeration of a smaller amount of abrasive particles provides a smaller surface area for grinding the wafer. Therefore, the material removal rate of the premixed slurry decreases over time. Agglomerates can scratch the dielectric and metal layers, resulting in higher wafer-level defect rates. This affects wafer-to-wafer (WtW) and batch-to-batch (LtL) polishing repeatability (e.g., consistent polishing speed and uniformity across wafers and across a die). In some embodiments, the first and second slurries agglomerate over time. Therefore, the removal rates of the first and second slurries are lower than those of the third slurry. In some embodiments, a removal rate of the oxide material layer is as follows: (a) approximately 790 Å / min using a first slurry with a flow rate of approximately 250 ml / min; (b) approximately 887 Å / min using a second slurry with a flow rate of approximately 250 ml / min; and (c) approximately 1061 Å / min using a third slurry with a flow rate of approximately 125 ml / min for both the abrasive solution and the additive solution. Based on the above, the removal rate of the oxide material layer using the third slurry is approximately 34% higher than the removal rate using the first slurry. In some embodiments, a removal rate of a SiN material layer is as follows: (a) approximately 345 Å / min using a first slurry with a flow rate of approximately 250 ml / min; (b) approximately 355 Å / min using a second slurry with a flow rate of approximately 250 ml / min; and (c) approximately 457 Å / min using a third slurry with a flow rate of approximately 125 ml / min for both the abrasive solution and the additive solution. Based on the above, the removal rate of the SiN material layer using the third slurry is approximately 32% higher than the removal rate using the first slurry.

[0044] The size of the abrasive particles can also affect the material removal rate across the wafer radius. For example, smaller abrasive particles can contribute to a lower material removal rate at the wafer edge (e.g., from about 146 mm to about 150 mm from the wafer center) compared to the wafer center. In other words, larger abrasive particles can provide a higher material removal rate at the wafer edge compared to the wafer center. Based on the above, the first and second slurries can provide a higher material removal rate at the wafer edge compared to the wafer center. Alternatively, due to the compaction and agglomeration of the abrasive components, the third slurry has a lower material removal rate at the wafer edge compared to the wafer center.

[0045] In some embodiments, the abrasive component may include one or more of cerium dioxide (CeO2), silicon dioxide (SiO2), and cerium hydroxide (Ce(OH)4). In some embodiments, imidazole (C3H4N2), which serves as a catalyst, may be added during the preparation of a Ce(OH)4-based abrasive solution. In some embodiments, the additive solution may include additive components such as acetic acid and ammonium acetate. In some embodiments, water-soluble polymers such as polyvinyl alcohol (PVA), polyethyleneimine (PEI), polyvinylpyrrolidone (PVP), peracetic acid (PAA), and polyvinyl glycol (PEG) may be added to the additive solution.

[0046] In some embodiments, the CMP system 100 can be configured to polish a substrate having a surface comprising different types of materials, such as silicon, germanium, arsenic, nitrogen, oxygen, and metals.

[0047] Reference Figure 1The CMP system 100 may also include a detection device 128 configured to measure polishing characteristics associated with a polishing process. Polishing characteristics may include one or more of the following: a polishing rate, a surface roughness, a surface uniformity, a surface dishing, a material composition of an exposed material layer, and a surface defect density associated with the substrate 105. In some embodiments, the detection device 128 may be configured to measure polishing characteristics during a polishing process. The detection device 128 may be an in-situ monitoring device attached to or embedded in a rotary platform 102. In some embodiments, the detection device 128 may be attached to a substrate carrier 104. The detection device 128 may include an optical interferometer or an optical reflector to generate an optical signal directed towards the substrate 105 and to detect a corresponding optical reflection signal associated with a thickness or surface roughness of a film (e.g., a copper layer) on the substrate 105. In some embodiments, the detection device 128 may include an electrode structure configured to detect a current or voltage associated with the film thickness or material composition of the exposed layer on the substrate 105. In some embodiments, the detection device 128 may be a device configured to measure one or more of a mechanical displacement, a force or torque, a vibration signal, an acoustic signal, a thermal signal, and a radioactive signal associated with polishing characteristics.

[0048] In some embodiments, computer system 108 may be configured to store one or more instructions for a polishing procedure, wherein the one or more instructions may include one or more parameters of the polishing procedure, such as the supply rate of one of the abrasive solution 112a and the additive solution 112b. Computer system 108 may be further configured to transmit one or more instructions to components of CMP system 100 via communication links 114, 116, 118, 124, and 126. In some embodiments, computer system 108 may receive detected polishing characteristics measured on wafer 105 and may be configured to generate an adjustment to one or more parameters of the polishing procedure based on the detected polishing characteristics. In some embodiments, the adjustment may be based on another polishing characteristic detected by another non-in-situ independent detection device, such as a stand-alone atomic force microscope (AFM). In some embodiments, the adjustment may be based on the flow rate of the abrasive solution 112a and the additive solution 112b based on a polishing characteristic, such as the surface profile or material composition of an exposed material layer on substrate 105.

[0049] Figure 4A , 4BFigures 4C and 4D illustrate different configurations of a CMP tool 400. The CMP tool 400 may have multiple platforms for performing pre-CMP procedures, CMP procedures, and post-CMP procedures. A pre-CMP procedure may be a pre-cleaning procedure to remove particles and / or contaminants from a wafer surface before undergoing a CMP procedure. Particles and contaminants may become trapped between the wafer and the polishing pad, scratching the wafer surface. The pre-cleaning procedure may be a wet cleaning, such as a DI water rinse, argon aerosol cleaning, or any other suitable cleaning procedure. A post-CMP procedure may include a CMP polishing procedure, in which residual slurry particles remaining on the wafer surface may be removed by brush scrubbing. Brush scrubbing may include, for example, cleaning the polished wafer surface with a soft polyvinyl alcohol (PVA) brush. After brush scrubbing, the polished wafer may be rinsed and dried with isopropyl alcohol (IPA).

[0050] For reference Figure 4A As described, the CMP tool 400 may include four platforms 402a, 402b, 404a, and 404b. A wafer can be loaded onto the CMP tool 400 using a loading port 402. A robotic arm can transfer the wafer from the loading port 402 to a processing chamber 403, and robot 403a can transfer the wafer from the processing chamber to two loading / unloading units 405a and 405b. Polishing heads for each of platforms 402a and 402b can load wafers onto platforms 402a and 402b. Platforms 402a and 402b can be configured to perform a CMP procedure on the wafer. Platforms 402a and 402b may be similar to... Figure 1 This is a portion of the illustrated CMP system 100. For example, platforms 402a and 402b may each have a distributor 110 fluidly connected to an abrasive solution mixing tank 120 and an additive solution mixing tank 122, a polishing pad 103, and a substrate carrier 104 communicatively connected to a computer system 108. Platforms 404a and 404b can be configured to perform post-CMP procedures on wafers polished on platforms 402a and 402b. Post-CMP procedures performed on platforms 404a and 404b may include polishing with a silica slurry and / or a buffing clean. After the post-CMP procedures, the wafers can be transferred back to the processing chamber 403 by means of a robot 403a. Figure 4A The processing chamber 403 on the CMP tool 400 shown may include a cleaning module 403b, which can perform pre- and post-polishing operations. Pre-polishing operations may include, for example, a pre-cleaning. Post-CMP procedures may include, for example, brush roller cleaning and / or IPA rinsing and drying.

[0051] For reference Figure 4BAs described, the CMP tool 400 may include four platforms 408a, 408b, 408c, and 410a. A wafer can be loaded onto the CMP tool 400 using a loading port 408. A robotic arm can transfer the wafer from the loading port 408 to a processing chamber 409, and robot 409a can transfer the wafer from the processing chamber to robot 410c. Robot 410c can load the wafer onto loading / unloading units 411a, 411b, and 411c. Polishing heads for each of platforms 408a, 408b, and 408c can respectively transfer the wafer to platforms 408a, 408b, and 408c. Each of platforms 408a, 408b, and 408c may have up to two polishing heads (not shown). Platforms 408a, 408b, and 408c can be assembled to perform a CMP procedure on the wafer. Platforms 408a, 408b, and 408c can be similar to Figure 1 This is a portion of the CMP system 100 illustrated. For example, platforms 408a, 408b, and 408c may each have a distributor 110 fluidly connected to an abrasive solution mixing tank 120 and an additive solution mixing tank 122, a polishing pad 103, and a substrate carrier 104 communicatively connected to a computer system 108. Platform 410a can be configured to perform post-CMP procedures on the wafer. After CMP, the wafer can be transferred to a loading / unloading unit 410b. One of the polishing heads on platform 410a can transfer the wafer from the loading / unloading unit 410b to platform 410a to perform post-CMP procedures. Platform 410a may have up to two polishing heads (not shown). After the post-CMP procedures, the wafer can be transferred back to the processing chamber 409 by means of a robot 409a. Figure 4B The processing chamber 409 on the CMP tool 400 shown may include a cleaning module 409b, which can perform pre- and post-polishing operations. Pre-polishing operations may include, for example, a pre-cleaning. Post-CMP procedures may include, for example, brush roller cleaning and / or IPA rinsing and drying.

[0052] For reference Figure 4C As described, the CMP tool 400 may include four platforms 412a, 412b, 412c, and 412d. A wafer can be loaded onto the CMP tool 400 using a loading port 412. A robotic arm can transfer the wafer from the loading port 412 to a processing chamber 413, and robot 413a can load the wafer from the processing chamber onto loading / unloading units 412e and 412f. Polishing heads for platforms 412a, 412b, 412c, and 412d can transfer the wafer from loading / unloading units 412e and 412f to platforms 412a, 412b, 412c, and 412d. Platforms 412a, 412b, 412c, and 412d can be assembled to perform a CMP procedure on the wafer. Platforms 412a, 412b, 412c, and 412d may be similar to... Figure 1This is a portion of the CMP system 100 illustrated. For example, platforms 412a, 412b, 412c, and 412d may each have a distributor 110 fluidly connected to the abrasive solution mixing tank 120 and the additive solution mixing tank 122, a polishing pad 103, and a substrate carrier 104 communicatively connected to the computer system 108. After the CMP process, the wafer can be transferred back to the processing chamber 413 by means of a robot 413a. Figure 4C The processing chamber 413 on the CMP tool 400 shown may include a cleaning module 413b, which can perform pre-polishing and post-polishing operations. Pre-polishing operations may include, for example, a pre-cleaning. Post-CMP procedures may include, for example, a brush roller cleaning and / or IPA rinsing and drying.

[0053] For reference Figure 4D As described, the CMP tool 400 may include four platforms 414a, 414b, 414c, and 414d. Wafers can be loaded onto the CMP tool 400 using loading port 414. A robotic arm can transfer wafers from loading port 414 to a processing chamber 415, and robot 415a can load wafers from the processing chamber onto loading / unloading units 416a, 416b, 416c, and 416d. Polishing heads for each of platforms 414a, 414b, 414c, and 414d can respectively transfer wafers to platforms 414a, 414b, 414c, and 414d. Each of platforms 414a, 414b, 414c, and 414d may have up to two polishing heads (not shown). Platforms 414a, 414b, 414c, and 414d can be assembled to perform a CMP procedure on a wafer. Each platform can have a corresponding loading / unloading phase. Platforms 414a, 414b, 414c, and 414d can be similar to... Figure 1 This is a portion of the CMP system 100 illustrated. For example, platforms 414a, 414b, 414c, and 414d may each have a distributor 110 fluidly connected to the abrasive solution mixing tank 120 and the additive solution mixing tank 122, a polishing pad 103, and a substrate carrier 104 communicatively connected to the computer system 108. After the CMP process, the wafer can be transferred back to the processing chamber 415 by means of a robot 415a. Figure 4D The processing chamber 415 on the CMP tool 400 shown may include a cleaning module 415b, which can perform pre-polishing and post-polishing operations. Pre-polishing operations may include, for example, a pre-cleaning. Post-CMP procedures may include, for example, a brush roller cleaning and / or IPA rinsing and drying.

[0054] Figure 5An exemplary method 500 for operating a polishing system such as a CMP system 100, according to some embodiments of the present disclosure. An exemplary method 500 for performing a CMP procedure on a wafer, according to some embodiments, is shown in... Figures 6A-6E For illustrative purposes, Figure 5 The example operation will refer to Figures 6A-6E The exemplary CMP procedure for polishing wafer 105 is illustrated below. According to some embodiments, method 500 may include (a) a polishing pad conditioning stage, (b) a planarization stage of the CMP procedure, (c) a selective polishing stage, and (d) a post-CMP cleaning procedure. The operations shown in exemplary method 500 are not exhaustive; other operations may be performed before, after, or between any illustrated operations. In some embodiments, the operations of exemplary method 500 may be performed in a different order. Variations of exemplary method 500 are within the scope of this disclosure.

[0055] Exemplary method 500 begins with operation 505, which involves adjusting a polishing pad using an adjusting disc. One surface of the polishing pad has a texture that facilitates the transfer of slurry to pores on that surface during polishing. During use, the pores on the polishing pad can become clogged, which reduces the pad's polishing ability. (See reference...) Figure 6A In some embodiments, during operation 505, the adjusting disk 106 can be used to scrape the surface of the polishing pad 103 to remove CMP byproducts or slurry particles from its own clogged pores to restore its performance. In some embodiments, while the adjusting disk 106 adjusts the polishing pad 103, DI water 608 can be dispensed onto the polishing pad 103 via the dispenser 110. The adjusting disk 106 can absorb DI water, which changes the coefficient of friction and a hardness of its surface. In some embodiments, during operation 505, the wafer 105 may not be lowered to form contact with the polishing pad 103.

[0056] Reference Figure 5 The exemplary method 500 proceeds to operation 510, in which a CMP procedure is performed on the wafer using a slurry. Since the first operation of the CMP procedure is a planarization stage to physically planarize a major portion of the exposed material layer (also referred to in this case as the "target layer") on the wafer, the slurry relies more heavily on an abrasive solution used to polish that material layer. See also... Figure 6B During operation 510, an abrasive solution 112a having a first flow rate is dispensed onto the polishing pad 103 through nozzle 110a. Simultaneously, an additive solution 112b having a second flow rate (less than the first flow rate) is dispensed onto the polishing pad 103 through nozzle 110b. The abrasive solution 112a and the additive solution 112b are mixed on the polishing pad 103 to form a slurry 112. The wafer 105 can be lowered to form contact with the polishing pad 103, such as... Figure 6CAs shown. A main body of the material layer on the polished wafer 105 using paste 112. As... Figure 6C As shown in the illustration, slurry 112 contacts a target layer 602, which has a stepped profile. Slurry 112 is a planarization material layer until one of the top surfaces of the material layer is within a predetermined distance from the stop layer 604, wherein the predetermined distance may be between about 5 nm and about 35 nm.

[0057] Reference Figure 5 During operation 515, polishing characteristics associated with the CMP process can be measured using detection device 128. For example, polishing characteristics of the polished height of a target layer can be measured. Polishing characteristics associated with the polishing process may also include one or more of the following: a polishing rate, a surface roughness, a surface uniformity, a surface conformity, a surface camber, and a surface defect density of a target substrate. Detection device 128 can be configured to measure one or more of an optical reflection, an optical refraction, an optical scattering, a voltage, and a current associated with the polishing process. In some embodiments, detection device 128 may be an electrode structure configured to measure a current, voltage, or plateau torque from wafer 105 associated with the thickness of the polished film or the material composition of the exposed layer during the polishing process. In some embodiments, polishing characteristics can be measured by an external detection device. For example, the surface roughness and / or dents (e.g., a polishing characteristic) of a target layer on wafer 105 can be measured using a stand-alone atomic force microscope (AFM). By continuously measuring and monitoring the proximity of a stop layer to the top surface of the exposed material layer on wafer 105, an endpoint of the planarization stage of the CMP process can be determined. The stop layer can be a material layer on wafer 105 to which the CMP process must stop or terminate. The stop layer prevents over-polishing.

[0058] Reference Figure 5 During operation 520, polishing characteristics, such as the polished height of one of the target layers on wafer 105, can be monitored in real time. A distance between the top surface of the exposed material layer and the stop layer on wafer 105 can be measured. If the stop layer is measured to be outside a predetermined distance from the polished height of the target layer, the CMP process can continue polishing wafer 105 as described in the planarization stage of operation 510. On the other hand, if the stop layer is measured to be within a predetermined distance from the top surface of the exposed material layer, the planarization stage can be terminated and the CMP process can continue to operation 525.

[0059] Reference Figure 5During operation 525, the CMP process switches from the planarization stage to a selective polishing stage. During the selective polishing stage, the flow rate of the abrasive solution can be reduced to decrease the physical abrasive components of the CMP process. To make the CMP process more selective for the stop layer, the flow rate of the additive solution can be increased. The total flow rate in the selective polishing stage can be the same as the total flow rate during the planarization stage. (Refer to...) Figure 6D For example, the flow rate of the abrasive solution 112a can be reduced from a first flow rate to a third flow rate, while the flow rate of the additive solution 112b can be increased from a second flow rate to a fourth flow rate. The abrasive solution 112a and the additive solution 112b can be blended to form a slurry 606. The decrease in the flow rate of the abrasive solution and the increase in the flow rate of the additive solution cause the additive solution to chemically react with the target layer to form byproducts on the wafer, and the abrasive solution assists in the physical removal of these byproducts from the wafer surface. The additive solution selectively removes the target layer and does not chemically react with the stop layer. After the stop layer is exposed, the selective polishing operation terminates. For example, such as... Figure 6D As shown in the illustration, slurry 606 can polish target layer 602 until stop layer 604 is exposed.

[0060] Reference Figure 5 During operation 530, byproducts remaining on the wafer surface from the CMP process are removed. For example, the surface of wafer 105 can be cleaned using a roller brush (not shown). The roller brush removes slurry particles, particles of abraded target layer 602, and byproducts of the chemical reaction between additive solution 112b and target layer 602 from the polished wafer surface. In some embodiments, DI water can be dispensed onto the polished wafer surface during the roller brush cleaning procedure. In some embodiments, the polished surface can be cleaned by rinsing with DI water. Figure 6E As shown, DI water 608 can be dispensed onto the polished wafer via dispenser 110. In some embodiments, the polished wafer surface can be cleaned using a silica slurry. In some embodiments, the silica slurry may include a quaternary ammonium salt to provide a higher silicon polishing rate compared to silicon oxide. In some embodiments, the wafer can be cleaned using DI water or a cleaning solution containing a water-soluble polymer. These water-soluble polymers may be wetting agents.

[0061] Figure 7This example illustrates polishing rate data 700 collected by a detection device 128 according to some embodiments. A horizontal and a vertical axis of the polishing rate data 700 represent a local portion of the substrate 105 (e.g., an edge portion or a central portion) and a corresponding optical or electrical signal associated with a film profile (e.g., a film thickness or a surface conformation) at that local portion of the substrate 105. Signals 702 and 704 are optical or electrical signals measured at two different measurement times. The corresponding polishing rate can be inferred based on a vertical interval between signals 702 and 704. In some embodiments, signal 702 or 704 may itself be associated with one or more of the following: a surface roughness, a height of the exposed material layer above an underlying layer, a surface uniformity, and surface camber of the substrate 105 at the respective measurement times.

[0062] Figure 8A This is an exemplary method for polishing an oxide layer on a partially manufactured substrate, according to some embodiments of the present disclosure. Method 800 performs operations similar to those included in method 500, and can be performed by means similar to... Figure 1 The polishing equipment of the CMP system 100 illustrated herein is used for polishing. Figure 8B-8D This shows a cross-sectional view of a partially fabricated wafer undergoing a CMP process as outlined in Method 800. The operations shown in Exemplary Method 800 are not exhaustive; other operations may be performed before, after, or between any illustrated operations. In some embodiments, the operations of Exemplary Method 800 may be performed in a different order. Variations of Exemplary Method 800 are within the scope of this disclosure.

[0063] Reference Figure 8A Method 800 begins with operation 805, in which the following can be formed: Figure 8B One of the locally manufactured substrates shown. Figure 8B The display shows a partially fabricated substrate 845 including a nanostructured channel layer 832 surrounded by a polysilicon gate structure 834 and an etch stop layer 840. An oxide layer 838 is formed on top of and surrounds the polysilicon gate structure 834. A gate capping layer 836 is disposed on top of the polysilicon gate structure 834. According to some embodiments, method 800 performs a CMP process to polish the oxide layer 838, the etch stop layer 840, the gate capping layer 836, and stop at one of the top surfaces of the polysilicon gate structure 834.

[0064] Reference Figure 8A It can be used Figure 1 The CMP system 100 shown performs operation 815 on the locally fabricated substrate 845 formed in operations 805 and 810. In operation 815, an oxide planarization operation is performed on the oxide layer 838. The oxide layer 838 can be as follows: Figure 6CThe example shown is flattened. For example... Figure 6C As shown, an abrasive solution 112a having a first flow rate and an additive solution 112b having a second flow rate can be dispensed onto a polishing pad 103 via a dispenser 110. The abrasive solution 112a and the additive solution 112b can be mixed on the polishing pad 103 to form a slurry 112. The first flow rate can be higher than the second flow rate. For example, the abrasive solution formed by 112a can have a flow rate of about 200 ml / min, and the additive solution 112b can have a flow rate of about 50 ml / min. Figure 8B The partially fabricated substrate shown can be attached to the substrate carrier 104. The oxide layer 838 can be removed by polishing with slurry 112 to remove one top portion of the oxide layer 838.

[0065] During the planarization operation, the detection device 128 can (a) monitor a polishing characteristic, such as step height (the height of the target layer above a lower layer) or the polished height of the oxide layer 838, and (b) determine the proximity of a top surface of the oxide layer 838 to a lower stop layer, which in this example may be a silicon layer forming the polysilicon gate structure 834. For example, such as Figure 8C As shown, the detection device 128 can detect a change in the signal indicating that the silicon layer forming the polysilicon gate structure 834 is within a predetermined distance from the top surface of one of the oxide layers 838. The signal change can be between about 20% and about 60% of an initial value. The detected signal can be transmitted to a computer system 108 to determine whether the silicon layer forming the polysilicon gate structure 834 is within a predetermined distance from the top surface of the oxide layer 838, wherein the predetermined distance can be between about 5 nm and about 35 nm.

[0066] In operation 820, if the silicon layer forming the polysilicon gate structure 834 is measured to be within the predetermined distance from the top surface of the oxide layer 838, the planarization operation terminates, and the method continues to operation 825. If, on the other hand, the silicon layer forming the polysilicon gate structure 834 is measured to be outside the predetermined distance from the top surface of the oxide layer 838, the oxide layer 838 is further polished using paste 112. At the termination of the planarization stage, partial wafer fabrication is exemplified in... Figure 8C middle.

[0067] Reference Figure 8A During operation 825, a selective polishing operation selectively removes the oxide layer and stops at a stop layer, which is the silicon layer forming the polysilicon gate structure. In operation 825, in... Figure 8C A selective polishing operation is performed on the oxide layer 838. The oxide layer 838 can be as follows: Figure 6D The example shown is selective polishing. For example... Figure 6DAs shown, an abrasive solution 112a having a third flow rate and an additive solution 112b having a fourth flow rate can be dispensed onto a polishing pad 103 via a dispenser 110. The abrasive solution 112a and the additive solution 112b can be blended on the polishing pad 103 to form a slurry 606. The fourth flow rate can be higher than the third flow rate. For example, the abrasive solution formed by 112a can have a flow rate of approximately 75 ml / min, and the additive solution 112b can have a flow rate of approximately 175 ml / min. Figure 8C The locally fabricated substrate shown can be attached to the substrate carrier 104. The oxide layer 838, gate capping layer 836, and any other suitable material layers above the top surface of one of the polysilicon gate structures 834 can be polished by paste 606. The higher flow rate of the additive solution 112b and the lower flow rate of the abrasive solution 112a facilitate a selective polishing operation that stops at the silicon layer forming the polysilicon gate structure 834, such as... Figure 8D As shown in the diagram. Finally, during operation 830, byproducts remaining on the surface of the local fabrication substrate 845 during the CMP process are removed.

[0068] In some embodiments, planarization and selective polishing operations can utilize abrasive solutions with different concentrations of abrasive components. Compared to selective polishing, planarization relies primarily on the abrasive solution used for polishing the oxide layer, thus allowing the use of a higher concentration of abrasive component in the abrasive solution. For example, the concentration of the abrasive component in the abrasive solution 112a dispensed during the planarization of the oxide layer 838 may be approximately 0.08% by weight. Figure 9 As shown, the removal rate of the oxide layer 838 using a slurry comprising an abrasive component of approximately 0.08% by weight in the abrasive solution 112a can be represented by curve 902. During the selective polishing operation, the abrasive or mechanical component of the CMP process is reduced to polish the remaining oxide layer 838, and the CMP process terminates at the silicon layer where the polysilicon gate structure 834 is formed. For example, the concentration of the abrasive component in the abrasive solution can be reduced to approximately 0.03% by weight. Figure 9 As shown, the removal rate of the oxide layer 838 using a slurry comprising an abrasive component of about 0.03% by weight in the abrasive solution 112a can be represented by curve 904.

[0069] In some embodiments, the removal rate increases with the downward pressure or force applied to wafer 105. For example, such as Figure 9 As shown, the removal rates of the oxide layer and the silicon nitride (SiN) layer increase linearly with pressure.

[0070] In some embodiments, the detection device and computer system may provide endpoint control. Endpoint control may (a) determine the termination of one of the planarization stages, and (b) perform a switch from the planarization stage to the selective polishing stage. For example, see reference... Figure 10A The detection device 128 can monitor a current, voltage, or plateau torque signal that determines the composition of one of the exposed material layers on the locally fabricated substrate 845. This signal can be transmitted to a computer system 108, which can control the concentration of the abrasive component in the abrasive solution 112a. According to some embodiments, the concentration of the abrasive component in the abrasive solution 112a changes from 0.08% Ce(OH)4 to approximately 0.03% Ce(OH)4 until time T1, when an upper portion of one of the oxide layers 838 can be polished using a slurry 112 having an abrasive solution 112a containing approximately 0.08% by weight of the abrasive component. Near time T1, the current, voltage, or plateau torque signal increases due to the change in the material composition of the exposed material layer. The change in the current, voltage, or plateau torque signal can be between approximately 20% and approximately 60% of a value prior to time T1. For example, the exposed material layer changes from oxide layer 838 to etch stop layer 840, and then to gate capping layer 836. At time T1, the planarization phase terminates and the selective polishing phase begins. According to some embodiments, at time T1, the abrasive solution is switched to use approximately 0.03% by weight of an abrasive component. According to some embodiments, during the selective polishing phase between times T1 and T2, a slurry 112 of abrasive solution 112a with approximately 0.03% by weight of an abrasive component is used. At time T2, the polysilicon gate structure 834 is exposed and the selective polishing phase terminates. The concentration of the abrasive component in slurry 112 can be varied by changing the flow rates of abrasive solution 112a and / or additive solution 112b, while keeping the total flow rate constant. In some embodiments, the concentration of the abrasive component in slurry 112 can be varied, for example, from 0.08% to 0.03% by decreasing the flow rate of abrasive solution 112a and increasing the flow rate of additive solution 112b, while keeping the total flow rate of abrasive solution 112a and additive solution substantially constant.

[0071] Higher abrasive compositions accelerate mechanical wear through exposed material layers. For example, such as Figure 10B and 10C As shown, compared to an abrasive solution with an abrasive component concentration of approximately 0.03% by weight, as shown in curve 1004, an abrasive solution with an abrasive component concentration of approximately 0.08% by weight, as shown in curve 1002, can exhibit a higher oxide removal rate. Figure 10C As shown, as the polishing time is increased using a slurry with an abrasive solution containing approximately 0.03% by weight of the abrasive component, the thickness profile of the oxide layer 838 across the substrate diameter does not change. Conversely, as Figure 10CAs shown, compared to the wafer center, pressing and agglomerating to avoid the formation of large particle clusters of abrasive components can avoid a higher oxide removal rate at the wafer edge.

[0072] Figure 11A This is an exemplary method for polishing a silicon nitride (SiN) layer on a partially fabricated substrate, according to some embodiments of the present disclosure. Method 1100 performs operations similar to those included in method 500, and can be performed by means similar to... Figure 1 The polishing equipment of the CMP system 100 illustrated herein is used for polishing. Figure 11B-11D This shows a cross-sectional view of a locally fabricated wafer undergoing a CMP process, as outlined by method 1100. The locally fabricated substrate 1145 includes a nanostructured channel layer 1132 surrounded by a polysilicon gate structure 1134. A first SiN layer 1135, an oxide layer 1136, and a second SiN layer 1138 are formed on top of the polysilicon gate structure 1134. According to some embodiments, method 1100 performs a CMP process to polish the second SiN layer 1138, the oxide layer 1136, and the first SiN layer 1135, stopping at one of the top surfaces of the polysilicon gate structure 1134. The operations shown in exemplary method 1100 are not exhaustive; other operations may be performed before, after, or between any illustrated operations. In some embodiments, the operations of exemplary method 1100 may be performed in a different order. Variations of exemplary method 1100 are within the scope of this disclosure.

[0073] Reference Figure 11A Method 1100 begins with operation 1105, in which the following can be formed: Figure 11B The partial fabrication substrate 1145 is shown. For example... Figure 11B As shown, a nanostructured channel layer 1132 surrounded by a polysilicon gate structure 1134 can be formed. In operation 1110, a first SiN layer 1135, an oxide layer 1136, and a second SiN layer 1138 can be formed on top of the polysilicon gate structure 1134.

[0074] Reference Figure 11A Operation 1115 can be achieved through Figure 1 The CMP system 100 shown is executed. In operation 1115, a planarization operation is performed on the second SiN layer 1138. The second SiN layer 1138 can be as follows: Figure 6C The example shown is used for flattening. For example... Figure 6CAs shown, an abrasive solution 112a having a first flow rate and an additive solution 112b having a second flow rate can be dispensed onto a polishing pad 103 via a dispenser 110. The abrasive solution 112a and the additive solution 112b can be mixed on the polishing pad 103 to form a slurry 112. The first flow rate can be higher than the second flow rate. For example, the abrasive solution formed by 112a can have a flow rate of about 200 ml / min, and the additive solution 112b can have a flow rate of about 50 ml / min. Figure 11B The partially fabricated substrate shown can be attached to the substrate carrier 104. The second SiN layer 1138 can be polished by paste 112 until (a) the oxide layer 1136 is exposed, or (b) one of the top surfaces of the second SiN layer 1138 is within a predetermined distance from one of the top surfaces of the polysilicon gate structure 1134, wherein the predetermined distance can be between about 5 nm and about 35 nm.

[0075] During the planarization operation, the detection device 128 can (a) monitor a polishing characteristic, such as step height or the polished height of the second SiN layer 1138, and (b) determine the proximity of a top surface of the second SiN layer 1138 to a lower stop layer, which in this example may be a silicon layer forming the polysilicon gate structure 1134. The detection device 128 can detect a change in a signal indicating that the silicon layer forming the polysilicon gate structure 1134 is adjacent to a top surface of the second SiN layer 1138. This change may be between approximately -20% and approximately 20% of an initial value. The detected signal may be transmitted to a computer system 108 to determine whether the silicon layer forming the polysilicon gate structure 1134 is within a predetermined distance from the top surface of the second SiN layer 1138, wherein the predetermined distance may be between approximately 5 nm and approximately 35 nm.

[0076] In operation 1120, if the top surface of one of the polysilicon gate structures 1134 is measured to be within the predetermined distance from the top surface of the second SiN layer 1138, the planarization operation terminates. If, on the other hand, the silicon layer forming the polysilicon gate structure 1134 is measured to be outside the predetermined distance from the top surface of the second SiN layer 1138, the second SiN layer 1138 is further polished using paste 112. At the termination of the planarization stage, partial wafer fabrication is illustrated in... Figure 11C middle.

[0077] Reference Figure 11AMethod 1100 may continue to operation 1125, during which a selective polishing operation selectively removes the oxide layer and the first SiN layer, and stops at a stop layer, which is the silicon layer forming the polysilicon gate structure. In operation 1125, a selective polishing operation is performed on the oxide layer 1136 and the first SiN layer 1135. The oxide layer 1136 and the first SiN layer 1135 may be as follows: Figure 6D The example shown is selective polishing. For example... Figure 6D As shown, an abrasive solution 112a having a third flow rate and an additive solution 112b having a fourth flow rate can be dispensed onto a polishing pad 103 via a dispenser 110. The abrasive solution 112a and the additive solution 112b can be blended on the polishing pad 103 to form a slurry 606. The fourth flow rate can be higher than the third flow rate. For example, the abrasive solution formed by 112a can have a flow rate of approximately 75 ml / min, and the additive solution 112b can have a flow rate of approximately 175 ml / min. Figure 11C The partially fabricated substrate shown can be attached to the substrate carrier 104. The oxide layer 1136, the first SiN layer 1135, and any other suitable material layers above the top surface of one of the polysilicon gate structures 1134 can be polished by means of paste 606. The higher flow rate of the additive solution 112b and the lower flow rate of the abrasive solution facilitate a selective polishing operation that stops at the silicon layer forming the polysilicon gate structure 1134, such as... Figure 11D As shown in the diagram. Finally, during operation 1130, byproducts remaining on the surface of the local fabrication substrate 1145 during the CMP process are removed.

[0078] In some embodiments, the detection device and computer system may provide endpoint control. Endpoint control may (a) determine the termination of one of the planarization stages, and (b) perform a switch from the planarization stage to the selective polishing stage. For example, see reference... Figure 12AThe detection device 128 can monitor a current, voltage, or plateau torque signal that determines the composition of one of the exposed material layers on the locally fabricated substrate 1145. This signal can be transmitted to a computer system 108, which can control the concentration of the abrasive component in the abrasive solution 112a. Up to time T1, the second SiN layer 1138 has been polished using a slurry 112 of the abrasive solution 112a having approximately 0.08% by weight of the abrasive component. Near time T1, the current, voltage, or plateau torque signal increases due to a change in the material composition of the exposed material layer. The change in the current, voltage, or plateau torque signal can be between approximately -20% and approximately 20% of a value prior to time T1. For example, the exposed material layer changes from the second SiN layer 1138 to an oxide layer 1136. At time T1, the planarization stage terminates and the selective polishing stage begins. At time T1, the abrasive solution can be switched to use approximately 0.03% by weight of the abrasive component. During the selective polishing phase between times T1 and T2, an abrasive solution 112a containing approximately 0.03% by weight of an abrasive component can be used. The concentration of the abrasive component in the slurry 112 can be varied by changing the flow rates of the abrasive solution 112a and / or the additive solution 112b, while keeping the total flow rate constant. In some embodiments, the concentration of the abrasive component in the slurry can be varied, for example, from 0.08% to 0.03% by decreasing the flow rate of the abrasive solution 112a and increasing the flow rate of the additive solution 112b, while keeping the total flow rate of the abrasive solution 112a and the additive solution constant. At time T2, the polysilicon gate structure 1134 is exposed and the selective polishing phase terminates.

[0079] Compared to selective polishing, planarization relies primarily on the abrasive solution used to polish the oxide layer, thus allowing the use of a higher concentration of abrasive components in the abrasive solution. For example, the concentration of the abrasive component in the abrasive solution 112a distributed during the planarization of the second SiN layer 1138 can be approximately 0.08% by weight. Figure 12B As shown, the removal rate of the second SiN layer 1138 using an abrasive solution with an abrasive component concentration of approximately 0.08% by weight can be represented by curve 1202. To reduce the abrasive or mechanical component in the CMP process during selective polishing to polish the first SiN layer 1135 and to stop the CMP process at the polysilicon gate structure 1134, the concentration of the abrasive component in the abrasive solution can be reduced to approximately 0.03% by weight. Figure 12B As shown, the removal rate of the second SiN layer 1138 using an abrasive solution with an abrasive component concentration of about 0.03% by weight can be represented by curve 1204.

[0080] In some embodiments, polishing time decreases as the concentration of the abrasive component in the abrasive solution increases. Higher abrasive components accelerate the mechanical wear of the material layer. For example, such as Figure 12B As shown, an abrasive solution with an abrasive component concentration of approximately 0.08% by weight can have a higher oxide removal rate compared to an abrasive solution with an abrasive component concentration of approximately 0.03% by weight. Figure 12C As shown, as the polishing time is increased using a slurry with an abrasive component of approximately 0.03% by weight, the thickness profile of the second SiN layer 1138 does not change. Conversely, as... Figure 12C As shown, compared to the wafer center, pressing and agglomerating to avoid the formation of large particle clusters of abrasive components can avoid a higher SiN removal rate at the wafer edge.

[0081] In some embodiments, the removal rate of one of the target layers does not increase indefinitely with increasing concentration of the abrasive component in the abrasive solution forming the slurry. For example, such as Figure 13 As shown, for lower concentrations of the abrasive component in the slurry, the removal rates of the SiN and oxide material layers increase linearly with increasing concentration (wt%) of the abrasive component in the slurry. The removal rates of the SiN and oxide layers reach a peak. When the concentration of the abrasive component in the slurry is higher, the removal rates of both the SiN and oxide material layers decrease. In some embodiments, the abrasive component Ce(OH)4 is adsorbed onto the oxide material layer to form a Ce-O-Si bond. The adsorbed abrasive component contains a positive charge. As the concentration of the abrasive component in the slurry increases, the electrostatic repulsion between the adsorbed abrasive component on the oxide material layer and the abrasive component in the slurry increases. When the concentration of the abrasive component in the slurry is higher, this may lead to a decrease in the removal rate of the oxide material layer, such as... Figure 13 As shown in the diagram. A similar mechanism also applies to the SiN material layer removal rate, such as... Figure 13 As shown in the image.

[0082] Various forms of exemplary embodiments may be implemented in software, firmware, hardware, or a combination thereof. Figure 14 This is an example of a computer system 1400, in which embodiments of or portions of the present disclosure are implementable as computer-readable code. Various embodiments of the present disclosure are described based on this example computer system 1400.

[0083] Computer system 1400 may be an example of computer system 108 and may include one or more processors, such as processor 1404. Processor 1404 is connected to a communication infrastructure 1406 (e.g., a bus or network).

[0084] Computer system 1400 also includes a main memory 1408, such as random access memory (RAM), and may also include an auxiliary memory 1410. Auxiliary memory 1410 may include, for example, a hard disk drive 1412, a removable storage drive 1414, and / or a memory stick. Removable storage drive 1414 may include a floppy disk drive, a magnetic tape drive, an optical disk drive, a flash memory, or the like. Removable storage drive 1414 reads from and / or writes to a removable storage unit 1418 in a well-known manner. Removable storage unit 1418 may include floppy disks, magnetic tapes, optical disks, and / or flash drives that are read from and written to by removable storage drive 1414. Removable storage unit 1418 includes a computer-readable storage medium storing computer software and / or data. Computer system 1400 includes a display interface 1402 (which may include input and output devices 1403, such as a keyboard and mouse), which forwards graphics, text and other data from communication infrastructure 1406 (or from a frame buffer that is not displayed).

[0085] In an alternative implementation, auxiliary storage 1410 may include other similar means for allowing computer programs or other instructions to be loaded into computer system 1400 (e.g., into main memory 1408). Such means may include, for example, a removable storage unit 1422 and an interface 1420. Examples of such means include a program cartridge and cartridge interface (such as those seen in video game devices), a removable memory chip (e.g., EPROM or PROM) and associated socket, and other removable storage units 1422 and interfaces 1420 that allow software and data to be transferred from removable storage unit 1422 to computer system 1400.

[0086] Computer system 1400 may also include a communication interface 1424. Communication interface 1424 allows software and data to be transferred between computer system 1400 and external devices. Communication interface 1424 may include a modem, a network interface (such as an Ethernet card), a communication port, or the like. Software and data transferred via communication interface 1424 are in the form of signals, which may be electronic, electromagnetic, optical, or other signals that can be received by communication interface 1424. These signals are provided to communication interface 1424 via a communication path 1426. Communication path 1426 carries signals and may be implemented using wires or cables, optical fibers, a telephone line, a cellular telephone link, an RF link, or other suitable communication channels.

[0087] In this document, the terms "computer program storage medium" and "computer-readable storage medium" are generally used to refer to non-transitory media such as removable storage unit 1418, removable storage unit 1422, and one of the hard disks installed in hard disk drive 1412. Computer program storage medium and computer-readable storage medium may also refer to memory, such as main memory 1408 and secondary memory 1410, which may be semiconductor memory (e.g., DRAM). Embodiments of this disclosure may utilize any computer-readable medium known now or in the future. Examples of computer-readable storage media include, but are not limited to, non-transitory main storage devices (e.g., any type of random access memory) and non-transitory secondary storage devices (e.g., hard disk drives, floppy disks, CD-ROMs, ZIP disks, magnetic tapes, magnetic storage devices, optical storage devices, MEMS, and nanotechnology storage devices).

[0088] These computer program products provide software for computer system 1400. Embodiments of this disclosure also refer to computer program products including software stored on any computer-readable storage medium. When such software is executed in one or more data processing devices, it causes one or more data processing devices(s) to operate as described herein.

[0089] The computer program (also referred to in this document as "computer control logic") is stored in main memory 1408 and / or auxiliary memory 1410. The computer program can also be received via communication interface 1424. When executed, this computer program enables computer system 1400 to implement various embodiments of the present disclosure. In particular, when executed, the computer program enables processor 1404 to implement programs of embodiments of the present disclosure, such as... Figure 5 The illustrated method 500, Figure 8A The illustrated method 800 and Figure 11A The operation in the illustrated method 1100. When implementing the embodiments of this disclosure using software, the software can be stored in a computer program product and loaded into the computer system 1400 using a removable storage drive 1414, interface 1420, hard disk drive 1412 or communication interface 1424.

[0090] The functions / operations described in the foregoing embodiments can be implemented in a wide variety of configurations and architectures. Therefore, some or all of the operations described in the foregoing embodiments—for example, Figure 1 The functions of the polishing system 100 described herein, Figures 6A-6E The functions of the polishing system 100 described herein, Figure 5 The illustrated method 500, Figure 8A The illustrated method 800 and Figure 11AThe method 1100 described herein can be executed in hardware, software, or a combination thereof in a computer system 1400 (e.g., via processor 1404). In some embodiments, a tangible device or article of manufacture, also referred to herein as a computer program product or program storage device, includes a tangible computer-usable or readable medium storing control logic (software). This includes, but is not limited to, computer system 1400, main memory 1408, secondary memory 1410, and removable storage units 1418 and 1422, as well as tangible articles of manufacture embodying any combination thereof. When such control logic is executed in one or more data processing devices (such as computer system 1400), it causes such data processing devices to operate as described herein. For example, hardware / devices may be connected to or be part of components 1428 of computer system 1400 ((multiple) remote devices, (multiple) networks, (multiple) entities 1428) or be part of components of computer system 1400.

[0091] This disclosure provides a CMP system 100 and a method 500, wherein slurry performance dependent on the mixing ratio of one of the abrasive solution 112a and the additive solution 112b can be optimized by controlling the flow rates of the abrasive and additive solutions 112a and 112b. In the disclosed CMP system 100 and method 500, the abrasive solution 112a and the additive solution 112b are dispensed onto a polishing pad 103 via two separate nozzles 110a and 110b and mixed on the polishing pad 103 to form a slurry. The concentration or mixing ratio of the abrasive solution 112a and the additive solution 112b can be adjusted so that an overall flow rate can be kept substantially constant. One advantage of this disclosure is that the CMP system 100 and method 500 use a single platform 102 and a single abrasive solution to provide an optimized CMP procedure for CMPing different dielectric layers. An optimized CMP procedure refers to a CMP procedure that can be modified to be effective for: (a) a planarization operation, which is a chemically and physically abrasive polishing procedure, and (b) a selective polishing operation, which is a chemical procedure in which an additive solution of a chemically reactive component selectively reacts with the material layer, while an abrasive component mechanically removes the material layer. During the planarization operation, the material layer can be removed primarily by chemically and physically abrasive. On the other hand, during the selective polishing operation, the material layer can be removed primarily by chemically and physically abrasive, while a stop layer is protected by a surface adsorption reaction.

[0092] In some embodiments, a method includes blending an abrasive solution and an additive solution to form a slurry on a polishing pad, contacting a substrate with the slurry on the polishing pad, wherein the substrate is held and rotated by a substrate carrier, and polishing an exposed layer on the substrate using the slurry. In some embodiments, the polishing may include monitoring a current, voltage, or torque measurement representing a material composition of the exposed layer, determining a change in the current, voltage, or torque measurement due to a change in the material composition of the exposed layer, and changing a first flow rate of the abrasive solution and a second flow rate of the additive solution based on the change in the signal. In some embodiments, the substrate may be cleaned after polishing.

[0093] In some embodiments, a polishing method includes chemically and mechanically polishing a material layer on a substrate using a first slurry formed from an abrasive solution and an additive solution, and measuring a polished height of the material layer. In some embodiments, in response to the polished height being within a predetermined distance from a stop layer on the substrate, the method includes switching from the first slurry to a second slurry formed from the abrasive solution and the additive solution, wherein the second slurry provides a higher material selectivity than the first slurry, and chemically and mechanically polishing the material layer using the second slurry.

[0094] In some embodiments, a polishing system includes a polishing pad configured to rotate on a platform, and a carrier configured to hold a substrate above and in contact with the polishing pad. In some embodiments, the polishing system further includes a dispenser comprising a first nozzle configured to dispense an abrasive solution onto the polishing pad and a second nozzle configured to dispense an additive solution onto the polishing pad to blend with the abrasive solution to form a slurry.

[0095] As will be understood from the foregoing discussion, the present invention can be embodied in various forms, including but not limited to the following:

[0096] Example 1. A method comprising:

[0097] An abrasive solution and an additive solution are mixed to form a slurry on a polishing pad;

[0098] A substrate is brought into contact with the slurry on the polishing pad, wherein the substrate is held and rotated by a substrate carrier;

[0099] Polishing one of the exposed layers on the substrate using the slurry, the polishing comprising:

[0100] Monitoring represents a current, voltage, or torque measurement representing one of the materials of the exposed layer;

[0101] The change in current, voltage, or torque measurements due to a change in the composition of the material of the exposed layer; and

[0102] The change in the current, voltage, or torque measurement is used to change a first flow rate of the abrasive solution and a second flow rate of the additive solution; and

[0103] Clean the substrate after polishing.

[0104] Example 2. The method of Example 1 further includes diluting an abrasive component in deionized (DI) water to form the abrasive solution.

[0105] Example 3. The method of Example 1 further includes diluting an abrasive component in deionized (DI) water to form the additive solution.

[0106] Example 4. The method of Example 1, wherein the blending comprises forming the slurry having a pH between about 4.0 and about 5.0.

[0107] Example 5. The method of Example 2 further includes changing the concentration of the abrasive component from a first concentration to a second concentration based on the change in the current, voltage or torque measurement, wherein the first concentration is greater than the second concentration.

[0108] Example 6. The method of Example 1, wherein changing the first flow rate of the abrasive solution includes changing from the first flow rate to a third flow rate, wherein the third flow rate is less than the first flow rate.

[0109] Example 7. The method of Example 6, wherein changing the second flow rate of the additive solution includes changing from the second flow rate to a fourth flow rate, wherein the second flow rate is less than the fourth flow rate.

[0110] Example 8. The method of Example 7 further includes maintaining the sum of the first and the second flow rates substantially equal to the sum of the third and the fourth flow rates.

[0111] Example 9. The method of Example 1, wherein cleaning the substrate includes scrubbing one of the top surfaces of the substrate with a roller brush.

[0112] Example 10. A polishing method, comprising:

[0113] A material layer on a substrate is chemically and mechanically polished using a first slurry formed from an abrasive solution and an additive solution.

[0114] The polished height of one of the material layers was measured;

[0115] In response to the polishing height being within a predetermined distance from a stop layer on the substrate, the first slurry is switched to a second slurry formed from the abrasive solution and the additive solution, wherein the second slurry provides a higher material selectivity than the first slurry;

[0116] The material layer was chemically and mechanically polished using the second slurry.

[0117] Example 11. The polishing method of Example 10 further includes mixing the abrasive solution and the additive solution on a polishing pad to form the first slurry.

[0118] Example 12. The polishing method of Example 10 further includes dispensing the abrasive solution at a first flow rate and dispensing an additive solution at a second flow rate to form the first slurry, wherein the first flow rate is greater than the second flow rate.

[0119] Example 13. The polishing method of Example 10 further includes dispensing the abrasive solution at a third flow rate and dispensing the additive solution at a fourth flow rate to form the second slurry, wherein the fourth flow rate is greater than the third flow rate.

[0120] Example 14. The polishing method of Example 10, wherein the first slurry contains an abrasive component having a first concentration, and the second slurry contains the abrasive component having a second concentration, wherein the second concentration is less than the first concentration.

[0121] Example 15. The polishing method of Example 10, wherein the pH of one of the first slurry and the second slurry is between about 4.0 and about 5.0.

[0122] Example 16. The polishing method of Example 10, wherein measuring the polished height includes monitoring one or more of a current, a voltage, or a plateau torque measurement.

[0123] Example 17. The polishing method of Example 16, wherein the switching from the first slurry to the second slurry is based on a change in at least one of the voltage, the current, or the platform torque measurement, wherein the change is between 20% and about 60% of an initial voltage, current, or platform torque measurement.

[0124] Example 18. A polishing system, comprising:

[0125] A polishing pad, which is assembled to rotate on a platform;

[0126] A carrier, assembled to hold a substrate above and in contact with the polishing pad; and

[0127] A distributor, comprising:

[0128] A first nozzle, configured to dispense an abrasive solution onto the polishing pad; and

[0129] A second nozzle, configured to dispense an additive solution onto the polishing pad to mix with the abrasive solution to form a slurry.

[0130] Example 19. The polishing system of Example 18 further includes a detection device configured to measure the polished height of a material layer on the substrate.

[0131] Example 20. The polishing system of Example 18 further includes a controller configured to communicate with a computer system configured to control a first flow rate of the abrasive solution and a second flow rate of the additive solution.

[0132] It will be understood that the detailed description section, rather than the summary section of the disclosure, is intended to be used to interpret the claims. The summary section of the disclosure may set forth one or more, but not all, possible embodiments of this disclosure as conceived by the inventors, and is therefore not intended to limit the appended claims in any way.

[0133] The foregoing disclosure outlines features of several embodiments, enabling those skilled in the art to better understand the nature of this disclosure. Those skilled in the art will understand that this disclosure can be readily used as the basis for designing or modifying other programs and structures to achieve the same purposes and / or advantages as the embodiments described herein. Those skilled in the art will also recognize that such equivalent constructions do not depart from the spirit and scope of this disclosure, and that various changes, substitutions, and modifications can be made to this application without departing from the spirit and scope of this disclosure.

Claims

1. A method for chemical mechanical polishing, characterized in that: Include: An abrasive solution and an additive solution are mixed to form a slurry on a rotating polishing pad; A substrate is brought into contact with the slurry on the polishing pad, wherein the substrate is held and rotated by a substrate carrier; Polishing one of the exposed layers on the substrate using the slurry, the polishing comprising: Monitoring represents a current, voltage, or torque measurement representing one of the materials of the exposed layer; The change in current, voltage, or torque measurements due to a change in the composition of the material of the exposed layer; and The change in the current, voltage, or torque measurement is used to change a first flow rate of the abrasive solution and a second flow rate of the additive solution; and Clean the substrate after polishing.

2. The method for chemical mechanical polishing as described in claim 1, characterized in that: It further includes diluting an abrasive component in deionized water to form the abrasive solution.

3. The method for chemical mechanical polishing as described in claim 1, characterized in that: It further includes diluting an abrasive component in deionized water to form the additive solution.

4. The method for chemical mechanical polishing as described in claim 1, characterized in that: Changing the first flow rate of the abrasive solution includes changing the first flow rate to a third flow rate, wherein the third flow rate is less than the first flow rate.

5. A polishing method, characterized in that: Include: A material layer on a substrate is chemically and mechanically polished using a first slurry formed from an abrasive solution and an additive solution. The polished height of one of the material layers was measured; In response to the polishing height being within a predetermined distance from a stop layer on the substrate, the first slurry is switched to a second slurry formed from the abrasive solution and the additive solution, wherein the second slurry provides a higher material selectivity than the first slurry; The material layer was chemically and mechanically polished using the second slurry.

6. The polishing method as described in claim 5, characterized in that: It further includes mixing the abrasive solution and the additive solution on a polishing pad to form the first slurry.

7. The polishing method as described in claim 5, characterized in that: It further includes dispensing the abrasive solution at a first flow rate and dispensing an additive solution at a second flow rate to form the first slurry, wherein the first flow rate is greater than the second flow rate.

8. A polishing system, characterized in that: Include: A polishing pad, which is assembled to rotate on a platform; A substrate carrier, assembled to hold a substrate above and in contact with the polishing pad; and A distributor, comprising: A first nozzle, configured to dispense an abrasive solution onto the polishing pad; and A second nozzle, configured to dispense an additive solution onto the polishing pad to mix with the abrasive solution to form a slurry.

9. The polishing system as described in claim 8, characterized in that: It also includes a detection device, which is assembled to measure the polished height of a material layer on the substrate.

10. The polishing system as claimed in claim 8, characterized in that: It also includes a controller configured to communicate with a computer system configured to control a first flow rate of the abrasive solution and a second flow rate of the additive solution.

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