Optical stack deposition and airborne metrology

Abstract

A method and apparatus for forming an optical stack having uniform and precise layers is provided. A processing tool for forming the optical stack includes a first transfer chamber, an onboard metrology unit, and a second transfer chamber in a closed environment. A first plurality of processing chambers are coupled to the first transfer chamber or the second transfer chamber. The onboard metrology unit is disposed between the first transfer chamber and the second transfer chamber. The onboard metrology unit is configured to measure one or more optical properties of each layer of the optical stack without exposing the layers to the surrounding environment.

Description

Technical Field

[0001]

[0013] Embodiments of the present disclosure generally relate to depositing and measuring optical stack layers in a processing tool. Background Art

[0002] The processing tool may include various deposition chambers for depositing materials such as dielectric layers or films on a substrate to form an optical stack. When forming an optical stack, the film is usually deposited as uniformly and accurately as possible. In order to determine whether the film has been deposited uniformly and accurately, the stack is removed from the deposition chamber for measurement using external metrology. However, the use of external metrology components exposes the film to air, causing the properties of the film to change improperly. Changes in the properties of the film may cause various errors or defects, such as causing the surface or interface of the film to deteriorate or become uneven. In addition, removing the stack from the processing tool environment to measure the film can be quite time-consuming, which reduces production time and reduces yield.

[0003] Therefore, there is a need for an apparatus and process for integrating reliable, accurate and precise metrology within a processing tool to form an optical stack with uniform layers and minimize errors or defects within the optical stack layers. Summary of the invention

[0004] A method and apparatus for forming an optical stack having uniform and precise layers is provided. A processing tool for forming the optical stack includes a first transfer chamber, an onboard metrology unit, and a second transfer chamber in a closed environment. A first plurality of processing chambers are coupled to the first transfer chamber or the second transfer chamber. The onboard metrology unit is disposed between the first transfer chamber and the second transfer chamber. The onboard metrology unit is configured to measure one or more optical properties of each layer of the optical stack without exposing the layers to the surrounding environment.

[0005] In one embodiment, a processing tool includes: a first transfer chamber, a second transfer chamber coupled to the first transfer chamber, one or more processing chambers coupled to the first transfer chamber or the second transfer chamber, and an onboard metrology unit disposed between the first transfer chamber and the second transfer chamber. The first transfer chamber, the second transfer chamber, and the onboard metrology unit are disposed in a closed environment.

[0006] In another embodiment, a method of forming an optical stack includes: depositing a first layer on a substrate in a first processing chamber; measuring one or more properties of the first layer using an onboard metrology unit; determining one or more errors in the first layer to be corrected in a subsequent layer; and depositing a second layer on the first layer in a second processing chamber. The method also includes measuring one or more properties of the second layer using the onboard metrology unit. The first processing chamber, the second processing chamber, and the onboard metrology unit are disposed in a closed environment.

[0007] In yet another embodiment, a processing tool includes a factory interface and a first transfer chamber, the factory interface is coupled to one or more front-opening wafer transfer boxes, and the first transfer chamber is coupled to the factory interface. The first transfer chamber includes a first set of robotic arms. The processing tool also includes a second transfer chamber coupled to the first transfer chamber. The second transfer chamber includes a second set of robotic arms. The processing tool also includes a plurality of chambers coupled to the first transfer chamber or the second transfer chamber. The plurality of chambers includes a first plurality of processing chambers and a plurality of support chambers. The processing tool also includes an onboard metrology unit disposed between the first transfer chamber and the second transfer chamber. The first transfer chamber, the second transfer chamber, and the onboard metrology unit are disposed in a vacuum environment. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] A more specific description of the present disclosure briefly summarized above may be obtained by reference to the embodiments, so that the above-mentioned features of the present disclosure can be understood in detail, some of which are illustrated in the accompanying drawings. It should be noted, however, that the drawings illustrate only exemplary embodiments and therefore should not be considered to limit the scope of the embodiments, and other equally effective embodiments may be allowed.

[0009] Figure 1 A processing tool for forming an optical stack is shown according to one embodiment.

[0010] Figure 2 A method of forming an optical stack using an onboard metrology unit is shown according to one embodiment.

[0011] Figure 3A-3B Various views of an optical stack formed using external metrology are shown according to one embodiment.

[0012] FIG. 4A to FIG. 4B Various views of an optical stack formed using an onboard metrology unit are shown according to another embodiment.

[0013] To facilitate understanding, identical reference numerals have been used, where possible, to designate identical elements that are common to the figures. It is contemplated that elements and features of one embodiment may be beneficially incorporated in other embodiments without repetition. DETAILED DESCRIPTION

[0014] A method and apparatus for forming an optical stack having uniform and precise layers is provided. A processing tool for forming the optical stack includes a first transfer chamber, an onboard metrology unit, and a second transfer chamber in a closed environment. A first plurality of processing chambers are coupled to the first transfer chamber or the second transfer chamber. The onboard metrology unit is disposed between the first transfer chamber and the second transfer chamber. The onboard metrology unit is configured to measure one or more optical properties of each layer of the optical stack without exposing the layers to the surrounding environment.

[0015] Figure 1 A top view of an exemplary processing tool 100 for forming an optical stack according to an embodiment of the present disclosure is shown.

[0016] The processing tool 100 generally includes a factory interface 102, which is suitable for receiving one or more substrate cassettes to be processed (substrates are, for example, 300 mm diameter wafers) from a front-opening wafer transfer box ("FOUP") 122. The FOUP 122 has one or more substrate carriers that are configured to temporarily and portable store substrates. The factory interface 102 may include various components not shown, such as an atmospheric robot, one or more loading ports, a holding station, a locking loading chamber, and / or a batch curing chamber, etc. The factory interface 102 provides a transition between the ambient environment of the factory and the internal closed environment of the processing tool 100 including multiple processing chambers 108A-108G. The internal closed environment of the processing tool 100 can be a vacuum environment or a pressurized environment. The internal closed environment of the processing tool 100 is isolated from the ambient environment including air.

[0017] The factory interface 102 is coupled to one or more buffers 104, which are configured to support processed and unprocessed substrates as the substrates are transferred to and from the factory interface 102. Once the one or more unprocessed substrates are placed on the buffer 104, a first set of robots 112 is configured to transfer the substrates to the first transfer chamber 106. The first set of robots 112 may include one or more arms. The first transfer chamber 106 may be coupled to one or more processing chambers 108A-108B. The first transfer chamber 106 is further coupled to one or more support chambers 124. The one or more support chambers 124 may include a degassing chamber, a storage chamber, a buffer chamber, a heating and / or cooling chamber, etc. The first set of robots 112 is configured to transfer substrates back and forth between the first transfer chamber 106 and the one or more processing chambers 108A-108B and the support chamber 124.

[0018] The first set of robots 112 is also configured to transfer the substrate from the first transfer chamber 106 to an on-board metrology (OBM) unit 110 mounted on top of or below the first cooling chamber 120. The second cooling chamber 114 is disposed adjacent to the first cooling chamber 120, and the first cooling chamber 120 is disposed above or below the OBM unit 110. The OBM unit 110, the first cooling chamber 120, and the second cooling chamber 114 are disposed between the first transfer chamber 106 and the second transfer chamber 116. The OBM 110, the first cooling chamber 120, and the second cooling chamber 114 may be disposed in a pass through chamber connecting the first transfer chamber 106 to the second transfer chamber 116. The first transfer chamber 106, the second transfer chamber 116, the first cooling chamber 120, and the second cooling chamber 114 are a uniform body. In one embodiment, the OBM unit 110 is disposed in a separate chamber coupled to the first or second transfer chambers 106, 116, such as an alternative support chamber 124 or process chamber 108C.

[0019] The second transfer chamber 116 includes a second set of robots 118. The second set of robots 118 may include one or more arms. The second set of robots 118 is configured to transfer substrates back and forth between the first cooling chamber 120 and / or the second cooling chamber 114 and the second transfer chamber 116. The second set of robots 118 is also configured to transfer substrates back and forth between the second transfer chamber 116 and one or more processing chambers 108C-108G coupled to the second transfer chamber 116. One or more of the one or more processing chambers 108A-108G may be coupled to only one of the first transfer chamber 106 or the second transfer chamber 116.

[0020] The processing chambers 108A-108G are configured to deposit layers such as dielectric films on the substrate to form an optical stack. The processing chambers 108A-108G can deposit optical films with high optical transparency to form an optical stack. For example, the films can include TiO 2 、 2 O 5 , Nb 2 O 5 , amorphous or polycrystalline silicon, SiO x N y 、AlO x N y , ITO, etc. Each film may have a thickness between about 5 nm and 500 nm.

[0021] The processing chambers 108A-108G may be any type of processing chamber, such as a chemical vapor deposition (CVD) chamber, an atomic layer deposition (ALD) chamber, a physical vapor deposition (PVD) chamber, an ion metal implantation (IMP) chamber, a plasma etch chamber, an annealing chamber, other furnace chambers, and the like. In one embodiment, the processing chambers 108A-108G are configured to deposit, anneal, cure, and / or etch a flowable dielectric film on a substrate. In one configuration, one or more of the processing chambers 108A-108G may be used to deposit a flowable dielectric material on a substrate. If desired, any of these processing chambers 108A-108G, or one or more additional processing chambers, may be coupled to the first and second transfer chambers 106, 116 and arranged to perform other conventional semiconductor device manufacturing processes, such as oxidation, film deposition, etching, heating, degassing, ashing, ion implantation, metrology, and the like, as applicable.

[0022] After depositing the film or layer on the optical stack, the first set of robots 112 and the second set of robots 118 are configured to place the stack below or above the OBM unit 110 on the first cooling chamber 120 to measure one or more properties of the deposited material. The OBM 110 is configured to measure one or more properties of the deposited layer by shining light onto the deposited layer and collecting reflected light returned from the deposited layer. The OBM 110 can be enclosed in an internal closed environment so that the properties of the deposited layer can be measured without destroying or damaging the environment.

[0023] In one embodiment, the OBM unit 110 includes at least one of a reflectometer and an ellipsometer. The OBM unit 110 may include a plurality of optical probes. The OBM unit 110 is configured to measure the optical reflectance spectrum of each deposited layer. The OBM unit 110 is also configured to measure various film properties, such as film thickness, optical reflectance spectrum, optical transmission spectrum, optical absorption spectrum, refractive index, distinction coefficient, composition, wafer curvature, and stress before and / or after processing the substrate. In response to the results of the OBM unit 110, various processing and hardware engineering knobs (not shown) provided on the processing tool 100 may be adjusted to precisely control the uniformity, density, smoothness, optical transparency, stress, and particle count of each individual layer.

[0024] The OBM unit 110 is also configured to provide real-time optical response feedback, thereby allowing subsequent layers to compensate for any errors detected in the measured layer. The results from the OBM unit 110 can be further used to develop algorithms for feed-forward thickness correction to ensure optimal spectral performance. For example, if a measured layer is determined to have an uneven thickness or other thickness error, then subsequently added layers can take into account the uneven thickness of the measured layer and compensate for such error. Thus, subsequently added layers can correct thickness errors in previously added layers.

[0025] By utilizing the OBM unit 110 to measure each deposited layer, various properties of each layer, such as thickness of each layer, surface roughness, layer uniformity, optical reflectance spectrum, and other optical properties, can be precisely and accurately controlled. In addition, because the OBM unit 110 is integrated with the processing tool 100, the internal closed environment will not be damaged or destroyed in order to measure the properties of each layer. Therefore, the layers will not be exposed to air or other surrounding environments, thereby reducing particle problems / contamination and surface / interface degradation. In addition, the OBM unit 110 disposed within the processing tool 100 allows real-time feedback to be obtained while the optical stack is being formed, thereby improving thickness accuracy and uniformity and increasing production.

[0026] Figure 2 A method 200 of forming an optical stack having uniform layers is shown according to one embodiment. The method 200 may be used in conjunction with Figure 1 The processing tool 100 is used together with the processing tool 100.

[0027] In operation 202, a substrate is placed in a processing chamber of a processing tool. The processing chamber can be any type of processing chamber, such as a CVD chamber, an ALD chamber, a PVD chamber, an IMP chamber, a plasma etch chamber, an annealing chamber, another furnace chamber, and the like.

[0028] In operation 204, one or more layers are deposited on the substrate to form an optical stack. The one or more layers may include materials with high optical transparency, such as TiO 2 、 2 O 5 , Nb 2 O 5 , amorphous or polycrystalline silicon, SiO x N y 、AlO x N y , ITO, etc. Each of the one or more layers may have a thickness of about 5-500 nm.

[0029] In operation 206, the stack is removed from the processing chamber and transported to an OBM unit disposed in a through chamber within the processing tool. Because the OBM unit is disposed within the processing tool, the internal closed environment will not be damaged or disrupted when the stack is transferred between the processing chamber and the OBM unit. Therefore, the layers of the stack will not be exposed to air or other surrounding environments, thereby reducing particle issues / contamination and surface / interface degradation.

[0030] In operation 208, one or more properties of one or more layers of the stack are measured using an OBM unit. The OBM unit is configured to measure one or more properties of the one or more layers by irradiating light onto the one or more layers and collecting reflected light returned from the one or more layers. The one or more properties measured may include thickness, optical reflection spectrum, optical transmission spectrum, optical absorption spectrum, refractive index, discrimination coefficient, composition, wafer bow, and stress.

[0031] In operation 210, any errors in the measured one or more layers are determined based on the measured properties for correction of subsequent layers. The errors are determined in real time, allowing subsequent layers to compensate for any errors detected in the one or more measured layers. The errors can be used to develop an algorithm for feed-forward thickness correction to ensure optimal spectral performance.

[0032] In operation 212, the stack is removed from the OBM unit and placed in another processing chamber in the processing tool. The processing chamber may be the same chamber used in operation 202, or the processing chamber may be a different chamber within the processing tool. The processing chamber may be any type of processing chamber, such as a CVD chamber, an ALD chamber, a PVD chamber, an IMP chamber, a plasma etch chamber, an annealing chamber, another furnace chamber, and the like.

[0033] In operation 214, one or more layers are deposited on the measured one or more layers of the stack to compensate for the error (if any) determined in operation 210. In one embodiment, the material of the deposited one or more layers has a different refractive index than the material of the measured one or more layers. The one or more layers may include a material with high optical transparency, such as TiO 2 、 2 O 5 , Nb 2 O 5 , amorphous or polycrystalline silicon, SiO x N y 、AlO x N y , ITO, etc. Each of the one or more layers may have a thickness of about 5-500 nm.

[0034] In operation 216, operations 206-214 are repeated one or more times to measure and add layers until the optical stack is fully formed. Each time one or more layers are added to the stack, the stack is placed in the OBM unit to measure one or more properties of the added layer. Then, any errors of the measured layer are determined based on the measured properties to be corrected in subsequent layers. The stack is then placed in another deposition chamber (or a previous deposition chamber), and then one or more layers are added again to the measured layer, which compensate for any previously determined errors. Thus, the processing tool continuously measures the properties of the stacked layers, determines any errors in these layers, and adds additional layers to the stack, which compensate for any errors. When operations 206-214 are repeated, operations 206-210 are optional and can be skipped. In this way, additional layers can be added to the stack without having to be measured by the OBM unit each time. Once the optical stack is fully formed, method 200 ends and the optical stack is removed from the processing tool.

[0035] Figure 3A-3B Various views of an optical stack 300 formed using external metrology components are shown according to one embodiment. Figure 3A-3B In an optical stack 300, a first layer 304 is deposited on a substrate 302, and the stack 300 is removed from a processing tool to measure properties of the first layer 304 using an external metrology component. After measuring the first layer 304, the stack 300 re-enters the internal environment of the processing tool, and a second layer 306 is deposited on the first layer 304. The stack 300 is then removed from the processing tool to measure properties of the second layer 306 using an external metrology component. After measuring the second layer 306, the stack 300 re-enters the internal environment of the processing tool, and a third layer 308 is deposited on the second layer 306. The stack 300 is then removed from the processing tool to measure properties of the third layer 308 using an external metrology component. Each time one of the layers 304, 306, 308 is measured, the internal environment is damaged or destroyed, and the layers 304, 306, 308 are exposed to air or other surrounding environment.

[0036] Figure 3A A non-magnified view of an optical stack 300 formed using external metrology is shown. The first layer 304, the second layer 306, and the third layer 308 may all include different materials, or the second layer 306 may include a different material than the first layer 304 and the third layer 308. Figure 3A As shown, the interface 310 between each layer 304, 306, 308 appears straight, indicating that the layers 304, 306, 308 are uniformly deposited.

[0037] Figure 3B Shows Figure 3A3B in the box labeled 3B. The enlarged view of the stack 300 shows a portion of the first layer 304, a portion of the third layer 308, and a second layer 306. Figure 3B As shown, the interface 310 between the layers 304, 306, 308 is not flat and straight, indicating that the layers 304, 306, 308 are not actually deposited uniformly or have a rough surface. The non-uniformity and roughness of the interface 310 may be the result of exposure to air or other surrounding environment when measured using an external metrology component. Exposing the layers 304, 306, 308 of the stack 300 to air may cause the layers 304, 306, 308 or the interface 310 to become contaminated or degraded, which in turn causes the interface 310 to become uneven or non-uniform.

[0038] Figure 4A-4B Various views of an optical stack 400 formed using an OBM unit are shown according to one embodiment. A processing tool 100 having an OBM unit 110 can be used to form the stack 400. To form Figure 4A-4B In an optical stack 400, a first layer 404 is deposited on a substrate 402, and the stack 400 is moved to an OBM unit within a processing tool to measure properties of the first layer 404. After measuring the first layer 404, any errors of the first layer 404 are determined, and a second layer 406 is deposited on the first layer 404, the second layer 406 compensating for the determined errors. The stack 400 is then moved to an OBM unit within the processing tool to measure properties of the second layer 406. After measuring the second layer 406, any errors of the second layer 406 are determined, and a third layer 408 is deposited on the first layer 404, the third layer 408 compensating for the determined errors. The stack 400 is then moved to an OBM unit within the processing tool to measure properties of the third layer 408. After measuring the third layer 408, any errors of the third layer 408 are determined. Each time one of the layers 404, 406, 408 is measured, the stack 400 remains within the internal closed environment of the processing tool, and the stack 400 is not exposed to air.

[0039] Figure 4A A non-enlarged view of an optical stack 400 formed using an OBM unit is shown. The first layer 404, the second layer 406, and the third layer 408 may all include different materials, or the second layer 406 may include a different material than the first layer 404 and the third layer 408. Figure 4A As shown, the interface 410 between each layer 404, 406, 408 appears straight, indicating that the layers 404, 406, 408 are uniformly deposited and have smooth, planar surfaces.

[0040] Figure 4B Shows Figure 4AAn enlarged or expanded view of a portion of stack 400 within the box labeled 4B in FIG. Figure 4B The magnification level is Figure 3B The enlarged view of stack 400 shows a portion of first layer 404, a portion of third layer 408, and a second layer 406. Figure 4B As shown, the interface 410 between the layers 404, 406, 408 is straight with little unevenness, indicating that the layers 404, 406, 408 are uniformly deposited. The stack 400 is prevented from being exposed to air or other ambient conditions using an OBM unit within the processing tool, which in turn prevents degradation or contamination that may cause the layers 404, 406, 408 and / or the interface 410 to be uneven.

[0041] By utilizing the OBM unit within the processing tool to measure each deposited layer, various properties of each layer, such as thickness of each layer, surface roughness, layer uniformity, optical reflectance spectrum, and other optical properties, can be precisely and accurately controlled. In addition, because the OBM unit is located within the processing tool, the internal closed environment will not be damaged or destroyed in order to measure the properties of each layer. Therefore, the layers will not be exposed to air or other surrounding environments, thereby reducing particle issues / contamination and surface / interface degradation. In addition, locating the OBM unit within the processing tool allows real-time feedback to be obtained while the optical stack is being formed, thereby improving thickness accuracy and uniformity and increasing production.

[0042] In one embodiment, a processing tool includes: a first transfer chamber, a second transfer chamber coupled to the first transfer chamber, one or more processing chambers coupled to the first transfer chamber or the second transfer chamber, and an onboard metrology unit disposed between the first transfer chamber and the second transfer chamber. The first transfer chamber, the second transfer chamber, and the onboard metrology unit are disposed in a closed environment.

[0043] The onboard metrology unit may include a reflectometer. The onboard metrology unit may include an ellipsometer. The onboard metrology unit may be configured to measure one or more optical properties of one or more layers of the optical stack. The one or more optical properties may be selected from the group consisting of: thickness, optical reflectance spectrum, optical transmission spectrum, optical absorption spectrum, refractive index, discrimination coefficient, composition, wafer bow, and stress. At least one of the one or more processing chambers coupled to the first transfer chamber or the second transfer chamber may be a physical vapor deposition chamber. At least one of the one or more processing chambers coupled to the first transfer chamber or the second transfer chamber may be a chemical vapor deposition chamber.

[0044] In another embodiment, a method of forming an optical stack includes: depositing a first layer on a substrate in a first processing chamber; measuring one or more properties of the first layer using an onboard metrology unit; determining one or more errors in the first layer to be corrected in a subsequent layer; and depositing a second layer on the first layer in a second processing chamber. The method also includes measuring one or more properties of the second layer using the onboard metrology unit. The first processing chamber, the second processing chamber, and the onboard metrology unit are disposed in a closed environment.

[0045] The onboard metrology unit may include one or more of a reflectometer and an ellipsometer. The one or more optical properties may be selected from the group consisting of: thickness, optical reflectance spectrum, optical transmission spectrum, optical absorption spectrum, refractive index, discrimination coefficient, composition, wafer bow, and stress. The material of the first layer may have a different refractive index than the material of the second layer. The method may further include depositing one or more additional layers on the second layer in the first processing chamber or the second processing chamber. After each additional layer is deposited, one or more properties of the additional layer may be measured using the onboard metrology unit, and one or more errors in the additional layer may be determined for correction in subsequent additional layers.

[0046] In yet another embodiment, a processing tool includes a factory interface and a first transfer chamber, the factory interface is coupled to one or more front-opening wafer transfer boxes, and the first transfer chamber is coupled to the factory interface. The first transfer chamber includes a first set of robotic arms. The processing tool also includes a second transfer chamber coupled to the first transfer chamber. The second transfer chamber includes a second set of robotic arms. The processing tool also includes a plurality of chambers coupled to the first transfer chamber or the second transfer chamber. The plurality of chambers includes a first plurality of processing chambers and a plurality of support chambers. The processing tool also includes an onboard metrology unit disposed between the first transfer chamber and the second transfer chamber. The first transfer chamber, the second transfer chamber, and the onboard metrology unit are disposed in a vacuum environment.

[0047] The onboard metrology unit may include a reflectometer. The onboard metrology unit may include an ellipsometer. The onboard metrology unit may be configured to measure one or more optical properties of one or more layers of the optical stack. The one or more optical properties may be selected from the group consisting of: thickness, optical reflectance spectrum, optical transmission spectrum, optical absorption spectrum, refractive index, discrimination coefficient, composition, wafer bow, and stress. At least one of the first plurality of processing chambers or the second plurality of processing chambers may be a physical vapor deposition chamber. At least one of the first plurality of processing chambers or the second plurality of processing chambers may be a chemical vapor deposition chamber.

[0048] While the foregoing is directed to embodiments of the present disclosure, other and further embodiments of the present disclosure may be devised without departing from the basic scope of the present disclosure, and the scope of the present disclosure is determined by the claims that follow.

Claims

1. A processing tool comprising: a first transfer chamber; a second transfer chamber coupled to the first transfer chamber, wherein one or more processing chambers are coupled to the first transfer chamber or the second transfer chamber; and An onboard metering unit, the onboard metering unit is arranged between the first transfer chamber and the second transfer chamber, wherein the first transfer chamber, the second transfer chamber and the onboard metering unit are arranged in a closed environment, wherein the onboard metering unit is configured as follows: measuring one or more optical properties of one or more layers of an optical stack; determining any errors in the one or more layers based on the measured one or more optical properties; and providing real-time optical response feedback to the process tool, wherein the process tool is configured to adjust at least one of a process engineering knob and a hardware engineering knob disposed on the process tool based on the feedback from the onboard metrology unit to compensate in a subsequently deposited layer for the error detected in the measured layer.

2. The processing tool of claim 1, wherein the onboard metrology unit comprises one or more of a reflectometer and an ellipsometer.

3. The processing tool of claim 1, wherein the one or more optical properties are selected from the group consisting of: thickness, optical reflection spectrum, optical transmission spectrum, optical absorption spectrum, refractive index, discrimination coefficient, composition, wafer bow, and stress.

4. The processing tool of claim 1, wherein at least one of the one or more processing chambers coupled to the first transfer chamber or the second transfer chamber is a chemical vapor deposition chamber.

5. The processing tool of claim 1, wherein at least one of the first one or more processing chambers coupled to the first transfer chamber or the second transfer chamber is a physical vapor deposition chamber.

6. A method of forming an optical stack, comprising: depositing a first layer on a substrate in a first processing chamber; measuring one or more properties of the first layer using an onboard metrology unit, wherein the onboard metrology unit is configured to provide feedback to a processing tool; determining one or more errors in the first layer for correction in a subsequent layer; adjusting at least one of a process engineering knob and a hardware engineering knob disposed on the process tool based on the feedback from the onboard metrology unit to compensate for the error detected in the first layer; depositing a second layer on the first layer in a second processing chamber; and One or more properties of the second layer are measured using the onboard metrology unit, wherein the first process chamber, the second process chamber, and the onboard metrology unit are disposed in a closed environment.

7. The method of claim 6, wherein the onboard metrology unit comprises one or more of a reflectometer and an ellipsometer.

8. The method of claim 6, wherein the one or more properties are selected from the group consisting of thickness, optical reflection spectrum, optical transmission spectrum, optical absorption spectrum, refractive index, discrimination coefficient, composition, wafer bow, and stress.

9. The method of claim 6, wherein the material of the first layer has a different refractive index than the material of the second layer.

10. The method of claim 6, further comprising: depositing one or more additional layers on the second layer in the first processing chamber or the second processing chamber, After each deposition of an additional layer, one or more properties of the additional layer are measured using the onboard metrology unit and one or more errors in the additional layer are determined for correction in subsequent additional layers.

11. The method of claim 6, further comprising: determining one or more errors in the second layer for correction in a subsequent layer; depositing a third layer on the second layer in a third processing chamber; and One or more properties of the third layer are measured using the onboard metrology unit.

12. A processing tool comprising: a factory interface coupled to one or more front-opening pods; a first transfer chamber coupled to the factory interface, the first transfer chamber comprising a first set of robotic arms; a second transfer chamber, the second transfer chamber being coupled to the first transfer chamber, the second transfer chamber comprising a second set of robotic arms; a plurality of chambers coupled to the first transfer chamber or the second transfer chamber, the plurality of chambers comprising a first plurality of processing chambers and a plurality of support chambers; as well as An onboard metrology unit, the onboard metrology unit is disposed between the first transfer chamber and the second transfer chamber, wherein the first transfer chamber, the second transfer chamber and the onboard metrology unit are disposed in a vacuum environment, wherein the onboard metrology unit is configured as follows: measuring one or more optical properties of one or more layers of an optical stack; determining any errors in the one or more layers based on the measured one or more optical properties; and providing real-time optical response feedback to the process tool based on the one or more optical properties measured, wherein the process tool is configured to adjust at least one of a process engineering knob and a hardware engineering knob disposed on the process tool based on the feedback from the onboard metrology unit to compensate in a subsequently deposited layer for the error detected in the measured layer.

13. The processing tool of claim 12, wherein the onboard metrology unit comprises one or more of a reflectometer and an ellipsometer.

14. The processing tool of claim 12, wherein the one or more optical properties are selected from the group consisting of: thickness, optical reflection spectrum, optical transmission spectrum, optical absorption spectrum, refractive index, discrimination coefficient, composition, wafer bow, and stress.

15. The processing tool of claim 12, wherein at least one processing chamber of the first plurality of processing chambers or the second plurality of processing chambers is a physical vapor deposition chamber, or At least one of the first plurality of processing chambers or the second plurality of processing chambers is a chemical vapor deposition chamber.

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