Lithographic apparatus and device manufacturing method

Abstract

A lithographic apparatus and device manufacturing method in which the amount of out-of-band radiation from an EUV radiation source, for example DUV radiation reaching the substrate, is taken into account in the dose controller to provide dose control based on actual effective dose, thereby providing better control of the effects of out-of-band radiation, for example the effects of out-of-band radiation on resist and imaging, in particular on imaging performance due to changes in wavelength-dependent sensitivity of the resist which depends on the type of resist.

Description

[0001] Cross-references to related applications

[0002] This application claims priority to U.S. Application No. 62 / 915,182, filed October 15, 2019, entitled “LITHOGRAPHIC APPARATUS ANDDEVICE MANUFACTURING METHOD,” the entire contents of which are incorporated herein by reference. Technical Field

[0003] This disclosure relates to photolithography equipment and methods for manufacturing devices. Background Technology

[0004] Extreme ultraviolet (EUV) radiation is electromagnetic radiation with wavelengths in the range of 5–20 nm and can be generated using plasma. Radiation systems for generating EUV radiation may include a laser for exciting a fuel (also called a target material) to provide plasma, and a source collector device for containing the plasma and collecting the EUV radiation. For example, plasma can be generated by directing a laser beam to a fuel, such as particles (e.g., droplets) of a suitable material (e.g., tin), or a suitable gas or vapor (e.g., Xe gas or Li vapor). The resulting plasma emits output radiation, such as EUV radiation, which is collected using a radiation collector. The radiation collector may be a mirror-type vertically incident radiation collector that receives the radiation and focuses it into a beam. The source collector device may include an enclosing structure or chamber arranged to provide a vacuum environment to support the plasma. Such radiation systems are commonly referred to as laser-generated plasma (LPP) sources.

[0005] One application of EUV radiation sources is photolithography. A photolithography apparatus is a machine that applies a desired pattern onto a substrate—typically onto a target portion of the substrate. Photolithography apparatus can be used, for example, in the manufacture of integrated circuits (ICs). In this case, a patterning apparatus (or mask or photomask) is used to generate a circuit pattern to be formed on an individual layer of the IC. This pattern can then be transferred to a target portion on the substrate (e.g., a silicon wafer), which may include a portion of one or more dies. The transfer of the pattern is typically performed via imaging onto a layer of radiation-sensitive material (resist) disposed on the substrate. Typically, a single substrate will contain a network of continuously patterned adjacent target portions.

[0006] To reduce the minimum printable size, imaging can be performed using radiation with short wavelengths. Therefore, EUV radiation sources providing EUV radiation in, for example, the 13–14 nm range have been proposed. It has also been proposed to use EUV radiation with wavelengths less than 10 nm, for example, in the 5–10 nm range, such as 6.7 nm or 6.8 nm. This type of radiation is referred to as extreme ultraviolet radiation or soft X-ray radiation.

[0007] In addition to the desired EUV radiation, EUV sources also produce non-EUV, out-of-band (e.g., deep ultraviolet (DUV)) radiation. This out-of-band radiation can penetrate the substrate and adversely affect the resulting image because the resist is sensitive to this out-of-band radiation. It is desirable to mitigate the effects of out-of-band radiation during the photolithography process. Summary of the Invention

[0008] The following is a simplified overview of one or more embodiments to provide a basic understanding of these embodiments. This overview is not an extensive summary of all contemplated embodiments and is not intended to identify key or essential elements of all embodiments, nor is it intended to depict the scope of any or all embodiments. Its sole purpose is to present some ideas of one or more embodiments in a simplified form as a prelude to the more detailed description that follows.

[0009] According to one aspect of an embodiment, a lithography apparatus comprising a source including an irradiation system configured to modulate a radiation beam, the radiation beam including EUV radiation and non-EUV radiation, and a controller adapted to control a radiation dose delivered by the irradiation system to a substrate based at least in part on a ratio of the energy magnitude of the non-EUV radiation to the energy magnitude of the EUV radiation. The non-EUV radiation may be DUV radiation. The apparatus may further include sensors, i.e., one or more sensors arranged to measure the energy magnitude of the DUV radiation. The sensors may be positioned to measure the energy magnitude of the DUV radiation at the substrate. The sensors may be positioned to measure the energy magnitude of the DUV radiation at the irradiation system. The apparatus may include modules configured to infer the energy magnitude of the DUV radiation based on a plurality of operating parameters of the source. The controller may be adapted to control the radiation dose delivered by the irradiation system to the substrate based at least in part on a product of a ratio and a calibration factor.

[0010] According to another aspect of the embodiments, a lithography apparatus is disclosed, comprising: an irradiation system configured to modulate a radiation beam, the radiation beam including both EUV radiation and non-EUV radiation; a first module configured to generate a first signal indicating the energy magnitude of the EUV radiation; a second module configured to generate a second signal indicating the energy magnitude of the non-EUV radiation; a third module configured to multiply the second signal by a calibration factor to obtain a third signal; a fourth module configured to add the first signal and the third signal to obtain a fourth signal; and a controller configured to receive the fourth signal and adapted to control the radiation dose delivered by the radiation beam to a substrate based at least in part on the sum of the product of the energy magnitude of the non-EUV radiation and the calibration factor and the energy magnitude of the EUV radiation. The non-EUV radiation may be DUV radiation. The second module may include at least one sensor arranged to measure the energy magnitude of the non-EUV radiation. The sensor may be positioned to measure the energy magnitude of the non-EUV radiation at the substrate. The sensor may be positioned to measure the energy magnitude of the non-EUV radiation at the irradiation system. The second module may be configured to infer the magnitude of the DUV radiation based on a plurality of operating parameters of the source.

[0011] According to another aspect of the embodiments, a method of manufacturing a device is disclosed, comprising: generating a radiation beam using a radiation source including an irradiation system, the radiation beam comprising both EUV radiation and non-EUV radiation; and controlling a radiation dose delivered to a substrate by the radiation beam based at least in part on a ratio of the energy magnitude of the non-EUV radiation to the energy magnitude of the EUV radiation. The non-EUV radiation may be DUV radiation. The method may include measuring the energy magnitude of the DUV radiation at the substrate or the irradiation system. The method may include inferring the energy magnitude of the DUV radiation based on a plurality of operating parameters of the source. Controlling the radiation dose delivered to the substrate by the radiation beam based at least in part on the ratio of the energy magnitude of the DUV radiation to the energy magnitude of the EUV radiation may be performed at least in part on the product of that ratio and a calibration factor.

[0012] According to another aspect of the embodiments, a method of manufacturing a device is disclosed, comprising: generating a radiation beam including both EUV radiation and non-EUV radiation; generating a first signal indicating the energy magnitude of the EUV radiation; generating a second signal indicating the energy magnitude of the non-EUV radiation; multiplying the second signal by a calibration factor to obtain a third signal; adding the first signal and the third signal to obtain a fourth signal; and providing the fourth signal to a dose controller. The dose controller controls the radiation dose delivered to a substrate by the radiation beam based at least in part on the sum of the product of the energy magnitude of the non-EUV radiation and the calibration factor and the energy magnitude of the EUV radiation. The non-EUV radiation may be DUV radiation. The method may include sensing the energy magnitude of the non-EUV radiation, which may include measuring the energy magnitude of the non-EUV radiation at the substrate. Generating the second signal indicating the energy magnitude of the non-EUV radiation may include inferring the magnitude of the non-EUV radiation based on a plurality of operating parameters of the source.

[0013] Other features and advantages of the invention, as well as the structure and operation of various embodiments thereof, are described in detail below with reference to the accompanying drawings. Note that the invention is not limited to the specific embodiments described herein. These embodiments are for illustrative purposes only. Other embodiments will be apparent to those skilled in the art based on the teachings contained herein. Attached Figure Description

[0014] The accompanying drawings, which are incorporated herein and form part of this specification, illustrate the invention and, together with the specification, further serve to explain the principles of the invention and enable those skilled in the art to make and use the invention.

[0015] Figure 1 A lithography apparatus with reflective projection optics is schematically depicted.

[0016] Figure 2 yes Figure 1 A more detailed view of the device.

[0017] Figure 3 This is a schematic depiction of a dose control device according to one aspect of an embodiment.

[0018] Figure 4 This describes one aspect according to an embodiment. Figure 3 A flowchart of the operation method of an embodiment.

[0019] Figure 5 This is a schematic diagram of a dose control device according to one aspect of an embodiment.

[0020] Figure 6 This describes one aspect according to an embodiment. Figure 5 A flowchart of the operation method of an embodiment.

[0021] Figure 7 This is a flowchart illustrating a method for determining calibration constants according to one aspect of an embodiment.

[0022] The features and advantages of the present invention will become more apparent from the following detailed description set forth in conjunction with the accompanying drawings, in which the same reference numerals consistently identify corresponding elements. In the drawings, the same reference numerals generally denote identical, functionally similar, and / or structurally similar elements. Detailed Implementation

[0023] This specification discloses one or more embodiments incorporating features of the present invention. The disclosed embodiments are merely illustrative. The scope of the invention is not limited to the disclosed embodiments. The invention is defined by the appended claims.

[0024] The described embodiments and references to "an embodiment," "embodiment," "example embodiment," etc., in the specification indicate that the described embodiments may include specific features, structures, or characteristics, but each embodiment may not necessarily include that specific feature, structure, or characteristic. Furthermore, these phrases do not necessarily refer to the same embodiment. Moreover, when a specific feature, structure, or characteristic is described in connection with an embodiment, it should be understood that implementing such a feature, structure, or characteristic in conjunction with other embodiments, whether explicitly described or not, is within the knowledge of those skilled in the art.

[0025] In the following description and claims, the terms “upper,” “lower,” “top,” “bottom,” “vertical,” “horizontal,” and similar terms may be used. These terms are used only to indicate relative orientation, and not any orientation relative to gravity. Similarly, terms such as left, right, front, back, etc., are intended to give only relative orientation.

[0026] Before describing the embodiments in more detail, it is beneficial to provide an example environment in which embodiments of the invention can be implemented.

[0027] Figure 1A lithography apparatus 100 including a source module SO is schematically illustrated according to an embodiment of the present invention. The apparatus includes: an irradiation system (irradiator) IL configured to modulate a radiation beam B (e.g., EUV radiation); a support structure (e.g., a mask stage) MT configured to support a patterning apparatus (e.g., a mask or stencil) MA and connected to a first positioner PM configured to precisely position the patterning apparatus; a substrate stage (e.g., a wafer stage) WT configured to hold a substrate (e.g., a wafer coated with resist) W and connected to a second positioner PW configured to precisely position the substrate; and a projection system (e.g., a reflective projection system) PS configured to project a pattern imparted by the radiation beam B by the patterning apparatus MA onto a target portion C (e.g., including one or more dies) of the substrate W.

[0028] Irradiation systems may include various types of optical components, such as refractive, reflective, magnetic, electromagnetic, electrostatic, or other types of optical components, or any combination thereof, for guiding, shaping, or controlling radiation.

[0029] The support structure MT holds the patterning apparatus MA in a manner dependent on the orientation of the patterning apparatus, the design of the lithography equipment, and other conditions (e.g., whether the patterning apparatus is kept in a vacuum environment). The support structure can use mechanical, vacuum, electrostatic, or other clamping techniques to hold the patterning apparatus. The support structure can be, for example, a frame or stage, which can be fixed or movable as needed. The support structure ensures that the patterning apparatus is in the desired position, such as relative to the projection system.

[0030] The term "patterning apparatus" should be interpreted broadly as any apparatus that can be used to pattern a radiation beam across its cross-section in order to generate a pattern in a target portion of a substrate. The pattern applied to the radiation beam may correspond to a specific functional layer in a device (e.g., an integrated circuit) created in the target portion.

[0031] Pattern forming apparatuses can be transmissive or reflective. Examples of pattern forming apparatuses include masks, programmable mirror arrays, and programmable LCD panels. Masks are well known in photolithography and include mask types such as binary, alternating phase-shift, and attenuation phase-shift masks, as well as various hybrid mask types. Examples of programmable mirror arrays employ a matrix arrangement of small mirrors, each of which can be individually tilted to reflect incoming radiation beams in different directions. The tilted mirrors impart a pattern to the radiation beam reflected by the mirror matrix.

[0032] Similar to illumination systems, projection systems can include various types of optical components, such as refractive, reflective, magnetic, electromagnetic, electrostatic, or other types, or any combination thereof, depending on the exposure radiation used, or other factors such as the use of a vacuum. It may be desirable to use a vacuum for EUV radiation because other gases may absorb too much radiation. Therefore, a vacuum environment can be provided throughout the beam path using vacuum walls and a vacuum pump.

[0033] As shown here, the device is reflective (e.g., using a reflective mask).

[0034] Photolithography equipment can be of the type having two (dual) or more substrate stages (and / or two or more mask stages). In such a "multi-stage" machine, additional stages can be used in parallel, or exposure can be performed using one or more other stages while preparation steps are being performed on one or more stages.

[0035] Reference Figure 1 The irradiator IL receives an extreme ultraviolet (EUV) radiation beam from the source module SO. Methods for generating EUV light include (but are not limited to) converting a material into a plasma state having at least one element (e.g., xenon, lithium, or tin) with one or more emission lines in the EUV range. In a method commonly referred to as laser-generated plasma (“LPP”), the desired plasma can be generated by irradiating a fuel, such as droplets, streams, or clusters of a material having the desired line-emitting element, with a laser beam. The source module 50 may include a laser (…). Figure 1 (Not shown) is part of an EUV radiation system used to provide a laser beam for exciting the fuel. The generated plasma emits output radiation, such as EUV radiation, which is collected using a radiation collector located in the source module. The laser and the source module can be separate entities, for example, when a CO2 laser is used to provide the laser beam for fuel excitation.

[0036] In this configuration, the radiation beam is delivered from the laser to the source module using a beam delivery system that includes, for example, suitable directional mirrors and / or beam expanders. The EUV source can be an integrated part of the source module, for example when the EUV source is a discharge-generated plasma EUV generator (often referred to as a DPP source).

[0037] A radiation beam B is incident on a pattern forming apparatus (e.g., a mask) MA held on a support structure (e.g., a mask stage) MT, and a pattern is formed by the pattern forming apparatus. After being reflected from the pattern forming apparatus (e.g., the mask) MA, the radiation beam B passes through a projection system PS, which focuses the radiation beam onto a target portion C of the substrate W. The substrate stage WT can be precisely moved, for example, to position different target portions C within the path of the radiation beam B, by means of a second locator PW and a position sensor PS2 (e.g., an interferometer, a linear encoder, or a capacitive sensor). Similarly, a first locator PM and another position sensor PS1 can be used to precisely position the pattern forming apparatus (e.g., the mask) MA relative to the path of the radiation beam B. The pattern forming apparatus (e.g., the mask) MA and the substrate W can be aligned using mask alignment marks M1, M2 and substrate alignment marks P1, P2.

[0038] The described apparatus can be used in at least one of the following modes: 1. In a stepping mode, the support structure (e.g., mask stage) MT and substrate stage WT remain substantially stationary while the entire pattern imparting the radiation beam is projected onto the target portion C at once (i.e., a single static exposure). The substrate stage WT is then moved in the X and / or Y directions so that different target portions C can be exposed. 2. In a scanning mode, the support structure (e.g., mask stage) MT and substrate stage WT are scanned synchronously while the pattern imparting the radiation beam is projected onto the target portion C (i.e., a single dynamic exposure). The velocity and direction of the substrate stage WT relative to the support structure (e.g., mask stage) MT can be determined by the magnification (reduction rate) and image inversion characteristics of the projection system PS. 3. In another mode, the support structure (e.g., mask stage) MT remains substantially stationary, thereby holding the programmable patterning apparatus in place, and the substrate stage WT is moved or scanned while the pattern imparting the radiation beam is projected onto the target portion C. In this mode, a pulsed radiation source is typically used, and the programmable patterning apparatus is updated as needed after each movement of the substrate stage WT or between consecutive radiation pulses during scanning. This operating mode can be readily applied to maskless lithography using programmable patterning apparatus, such as the programmable mirror arrays described above.

[0039] Alternatively, the above usage patterns or combinations and / or variations of completely different usage patterns may be adopted.

[0040] Figure 2 An embodiment of the photolithography apparatus is shown in more detail, including a radiation system 42, an illumination system IL, and a projection system PS. (As shown...) Figure 2The radiation system 42 shown is of the type that uses laser-generated plasma as the radiation source. EUV radiation can be generated by converting gases, vapors, or liquids (continuous streams or droplets) (e.g., Xe gas, Li vapor, or Sn vapor or droplets) using a laser, producing a very hot plasma in the aforementioned gases, vapors, or liquids (continuous streams or droplets) to emit radiation in the EUV range of the electromagnetic spectrum. The very hot plasma is generated by, for example, photoexcitation using a CO2 laser to induce at least partial ionization of the plasma. To efficiently generate radiation, a partial pressure of, for example, 10 Pa of Xe, Li, Sn vapor, or any other suitable gas or vapor may be required. In one embodiment, Sn is used to generate the plasma in order to emit radiation in the EUV range.

[0041] Radiation system 42 embodies Figure 1 The function of the source SO in the device. Radiation system 42 includes source chamber 47, which in this embodiment not only substantially surrounds the EUV radiation source, but also includes collector 50, in Figure 2 In the example, collector 50 is a vertically incident collector, such as a multilayer mirror.

[0042] As part of the LPP radiation source, the laser system 61 is configured and arranged to provide a laser beam 63, which is delivered by the beam delivery system 65 through an aperture 67 disposed in the collector 50. Furthermore, the radiation system includes target material 69, such as Sn or Xe, provided by the target material source 71. In this embodiment, the beam delivery system 65 is arranged to establish a beam path substantially focused on the desired plasma formation location 73.

[0043] In operation, target material 69 (also referred to as fuel) is supplied in droplet form by target material supply source 71. When this droplet of target material 69 reaches plasma formation position 73, laser beam 63 strikes the droplet and forms EUV radiation emitting plasma within source chamber 47. In the case of a pulsed laser, this involves timing the laser radiation pulses to coincide with the passage of the droplet through position 73. As mentioned above, the fuel can be, for example, xenon (Xe), tin (Sn), or lithium (Li). These produce highly ionized plasmas with electron temperatures of 30–50 eV. High-energy EUV radiation can be generated using other fuel materials, such as Tb and Gd. The high-energy radiation generated during the de-excitation and recombination of these ions includes the desired EUV emitted from the plasma at position 73. Plasma formation position 73 and aperture 52 are located at the first and second focal points of collector 50, respectively, and EUV radiation is focused by vertically incident collector reflector 50 onto intermediate focal point IF.

[0044] The radiation beam emitted from source chamber 47 passes through the illumination system IL via so-called vertical incident reflectors 53 and 54, such as... Figure 2 The radiation beam 56 is shown in the diagram. A vertically incident reflector guides beam 56 onto a patterning device (e.g., a mask or photomask) positioned on a support (e.g., a photomask or photomask stage) MT. A patterned beam 57 is formed, which is imaged by the projection system PS onto a substrate supported by a wafer stage or substrate stage WT via reflective elements 58 and 59. More elements than are shown may typically be present in the illumination system IL and the projection system PS.

[0045] For example, there can be a ratio Figure 2 The two elements 58 and 59 shown may have one, two, three, four, or even more reflective elements. Radiation collectors similar to radiation collector 50 are known from the prior art.

[0046] As those skilled in the art will know, reference axes X, Y, and Z can be defined for measuring and describing the geometry and behavior of the device, its various components, and radiation beams 55, 56, 57. Local reference frames for the X, Y, and Z axes can be defined in each part of the device. The Z-axis is approximately coincident with the direction of the optical axis O at a given point in the system and is generally perpendicular to the plane of the patterning apparatus (mask) MA and the plane of the substrate W. In the source module (device) 42, the X-axis is approximately coincident with the direction of the fuel flow (69, as described below), while the Y-axis is orthogonal to it, pointing outwards as shown. On the other hand, near the support structure MT that holds the mask MA, the X-axis is generally transverse to the scan direction aligned with the Y-axis. For convenience, in Figure 2 In this area of ​​the schematic diagram, the X-axis points outside the page, again as marked. These markings are conventional in the art and are adopted herein for convenience. In principle, any frame of reference can be chosen to describe the device and its behavior.

[0047] In addition to the required EUV radiation, the plasma also produces radiation of other wavelengths, such as those in the visible, UV, and DUV ranges. There is also IR (infrared) radiation from the laser beam 63. Non-EUV wavelengths are not required in the irradiation system IL and the projection system PS, and various measures can be taken to block non-EUV radiation. For example... Figure 2As illustrated schematically, a transmission spectrum filter (SPF) can be applied upstream of the virtual source point IF. Those skilled in the art will understand that, alternatively, a transmission SPF can be provided downstream of the virtual source point IF. As an alternative or supplement to such a filter, the filtering function can be integrated into other optical components. Therefore, filters for DUV and other unwanted wavelengths can be provided at one or more locations along the path of beams 55, 56, and 57 within the source module (radiation system 42), the illumination system IL, and / or the projection system PS, and / or the aforementioned wafer stage (WT). Despite these measures, residual DUV radiation may still be present in the radiation beam.

[0048] To deliver fuel, such as liquid tin, a droplet generator or target material source 71 is arranged within source chamber 47 to emit a stream of droplets toward plasma formation location 73. In operation, a laser beam 63 can be delivered synchronously with the operation of the target material source 71 to deliver radiation pulses, thereby converting each fuel droplet into plasma. The droplet delivery frequency can be several kilohertz, or even tens or hundreds of kilohertz. In practice, the laser beam 63 can be delivered by laser system 61 in at least two pulses: a pre-pulse (PP) with finite energy is delivered to the droplet before it reaches the plasma location to expand the fuel material into a disk-shaped target or evaporate the fuel material into a small cloud, and then a main pulse (MP) of laser energy is delivered to the cloud at the desired location to generate plasma. In a typical example, the plasma diameter is approximately 300 μm to 800 μm. A trap 72 is positioned on the opposite side of the surrounding structure 47 to capture fuel that has not yet become plasma, regardless of the cause.

[0049] Laser system 61 can be, for example, of the MOPA (Master Oscillator Power Amplifier) ​​type. Such laser system 61 includes a "master" laser or "seed" laser followed by a power amplifier system PA for emitting a main pulse of laser energy to an extended disk-shaped target or droplet cloud; and a pre-pulse laser for emitting a pre-pulse of laser energy to the droplets. A beam delivery system 65 is provided to deliver laser energy 63 into source chamber 47. In practice, the pre-pulse element of the laser energy can be delivered by a separate laser. Laser system 61, target material source 71, and other components can be controlled by a controller (not shown separately). The controller performs numerous control functions and has sensor inputs and control outputs for various elements of the system. Sensors can be located within and around elements of radiation system 42, and optionally elsewhere in the lithography apparatus. In some embodiments of the invention, the main pulse and pre-pulse originate from the same laser. In other embodiments of the invention, the main pulse and pre-pulse are derived from different lasers that are independent of each other but controlled to operate synchronously. To block as many contaminants as possible, some type of contaminant trap 80 can be provided between the plasma formation location 73 and the optical elements of the beam delivery system 65.

[0050] As mentioned above, both LPP and discharge-generated plasma (DPP) EUV sources emit broad wavelength spectra, including the desired EUV radiation (13.5 nm) and other out-of-band wavelengths. In this context, out-of-band wavelengths can include deep ultraviolet (DUV) radiation (from approximately 130 nm to 400 nm) and beyond. When the target material used is tin, this DUV radiation is emitted from the low-density, low-temperature portion of the plasma. The DUV portion of the emitted light is a byproduct of EUV plasma emission and, in principle, can propagate to the wafer through irradiators and projection optics, affecting imaging performance by contributing to exposure in the photoresist. This is because the photoresist at the wafer is sensitive not only to 13.5 nm EUV light but also to other out-of-band wavelengths. At the scanner wafer level, typical chemically activated resists (CARs) used for EUV are highly sensitive to DUV.

[0051] Practical EUV imaging performance is adversely affected by the non-EUV out-of-band content of the spectrum. This non-EUV portion of the spectrum contains only wavelengths too long to resolve features of interest at the mask (MA) on the wafer (W), thus only reducing image contrast. Consequently, imaging performance (e.g., critical dimensional uniformity (CDU), image arrangement) is affected, especially at edges and corners adjacent to the die, and imaging and optical process correction (OPC) (e.g., for matching between two different lithography tools) are compromised. Therefore, parasitic DUV radiation propagating to the wafer along with in-band EUV radiation has an impact on the aerial image used for monitoring and controlling the lithography process.

[0052] The presence of DUV radiation also affects dose control, i.e., the amount of radiation supplied to the wafer during exposure. This control is complex due to inherent beam characteristic drift in LPP EUV sources, such as drift caused by cold-to-thermal conversion of the driving laser, degradation of the master / seed pulse laser over time, and changes in driving laser gain commands (from the control module). Furthermore, Sn plasma emission does not remain constant during production, as indicated by the fact that the conversion efficiency (CE) is not constant. This also means that the ratio of the energy of the DUV radiation to the energy of the EUV radiation from the plasma and at the wafer level (DUV / EUV ratio) varies.

[0053] Furthermore, when the relative sensitivity of the resist to non-EUV and EUV depends on the resist type, variations in resist sensitivity can adversely affect imaging performance. Controlling the total effective dose, including the non-EUV component, provides the ability to mitigate the effects of wavelength-dependent resist sensitivity.

[0054] Conventionally, dose control—the control of the amount of energy (per unit area) that the photoresist undergoes during exposure through a photolithography system—is based on measurements from in-band EUV metrology, which ensures a constant in-band EUV energy at the wafer level. However, as a result, the DUV / EUV ratio may drift, and the wafer-level DUV energy may drift as a function of time. DUV energy drift can be expected to cause a critical dimension (CD) drift on the product wafer. For a constant in-band EUV dose but with drift, such as increased DUV energy, the photoresist will experience a higher effective dose, resulting in a smaller or larger CD depending on the hue of the photoresist.

[0055] In other words, from a CD (Crystal Detector) perspective, if DUV energy drift is allowed, the net effective dose will drift. From this perspective, the effective dose is a combination of in-band (EUV) and out-of-band (DUV) energy. One way to model the effective dose is to sum the EUV energy to some constant multiplied by the DUV energy. For some applications, it is desirable to control (e.g., keep constant) this effective dose, rather than simply controlling the wafer-level EUV dose.

[0056] One option for controlling the effective dose is to add a DUV / EUV ratio control loop to the dose control algorithm to ensure the DUV / EUV ratio remains constant, thus maintaining a constant effective dose at the wafer level. Again, the effective dose D... E This can be determined as follows:

[0057] D E =E EUV (1+K*E DUV / EEUV )

[0058] Where D E It is the effective dose, E EUV It is the internal EUV energy, E DUV It is the out-of-band DUV energy, and K is a constant, for example, determined empirically or through simulation. Or, if

[0059] R = DUV / EUV ratio = E DUV / E EUV

[0060] but

[0061] D E =E EUV (1+KR)

[0062] Effective dose can be controlled by manipulating the pre-pulsed laser or the main pulse beam size at the target (e.g., by controlling the pressure in the pressurized pre-pulsed module). In various implementations of dose control techniques, numerical simulations can be used to model, calculate, or estimate EUV and non-EUV emissions from thermally dense plasmas.

[0063] Figure 3 An example of a system implementing this dose control method is illustrated schematically. Figure 3 In the illustrated arrangement, the dose controller 310 includes a module 320 configured to control the EUV dose generated by the EUV source 300. The amount of EUV radiation is measured by a sensor 330, which generates an output applied to the dose controller 310 as a feedback input. Simultaneously, a sensor 340 senses the amount of DUV radiation and provides it to the control module 330, which serves as another control loop within the controller 310. The control module 330 controls the effective dose based on the DUV / EUV ratio. In this context, an example of an EUV sensor is one configured to measure power in the electromagnetic spectrum, for example, between 13.2–13.8 nm, 13–14 nm, 10–15 nm, 5–20 nm, 10–30 nm, or other wavelength ranges suitable for EUV lithography processes. In this context, an example of a DUV sensor is a sensor configured to measure power in the electromagnetic spectrum, for example, between approximately 14 nm, approximately 15 nm, approximately 30 nm, approximately 40 nm, approximately 50 nm, approximately 100 nm, approximately 130 nm, or approximately 200 nm (or other wavelengths associated with the lower limit of out-of-band radiation in EUV lithography processes) and approximately 200 nm, approximately 250 nm, approximately 300 nm, approximately 350 nm, or approximately 400 nm.

[0064] Figure 4 It is a description Figure 3A flowchart illustrating the operating mode of the system is provided. In step S100, the amount of EUV energy at the substrate is input to the dose controller. In step S110, the amount of DUV energy at the substrate is input to the dose controller. In step S120, the dose controller controls the total effective dose based on the two inputs, which contribute to the EUV energy and DUV energy. It will be apparent to those skilled in the art that steps S100 and S110 can occur simultaneously.

[0065] Another approach is to use a conventional current dose control algorithm to control the effective EUV dose (instead of just the in-band EUV dose), using the calibrated effective dose (E EUV +K*E DUV () as input. Figure 5 An example of a system implementing this dose control method is illustrated schematically. Figure 5 In the arrangement shown, the dose controller 310 includes module 320. The amount of EUV radiation is measured by sensor 330, which generates an output. Simultaneously, the amount of DUV radiation is sensed by sensor 340. Sensor 340 generates an output signal, which is multiplied by a constant K in module 350 and then added to the signal from EUV sensor 330 at summation point 360. The resulting signal is provided to control module 320.

[0066] Figure 6 It is a description Figure 5 A flowchart illustrating the operating mode of the system is provided. In step S200, a signal indicating the amount of EUV energy at the substrate is generated. In step S210, a signal indicating the amount of DUV energy at the substrate is generated. In step S240, the DUV energy signal is multiplied by a constant K. In step S250, the multiplied DUV energy signal is added to the EUV energy signal. The resulting sum is then provided to a dose controller, which performs dose control based on the sum. It will be apparent to those skilled in the art that steps S200 and S210 can occur simultaneously.

[0067] DUV energy can be obtained in any of several ways. For example, one or more DUV sensors configured to measure the magnitude of DUV energy at the wafer level or in an irradiation system can be used. That is, a sensor operable on the lithography tool to directly sense the spectral content of out-of-band radiation can be provided. Figure 2The sensor 90 is illustrated. The spectral measurements of step S110 or S210 can then be performed directly using the sensor 90. This sensor can be used at the wafer level (e.g., on the wafer stage WT), allowing any spectral measurement to take into account the illumination and projection optics, as well as any transmission effects prior to the wafer stage. However, the sensor can be placed elsewhere. This sensor can be part of a lithography apparatus or a standalone sensor inserted only when a test is performed at a specific location (e.g., near the wafer stage WT). The sensor can operate in a spectral range of 10 to 400 nm, but is not limited to this range. The illumination characteristics can then be adjusted based on the spectral data recorded using the sensor.

[0068] Alternatively or in combination, a DUV indicator can be derived by determining how the DUV energy varies with the measured parameters and then inferring the DUV energy from those parameters. For example, if the DUV energy is a function of several key source operating parameters—such as conversion efficiency, master pulse energy, master pulse beam size, and / or target size—the effective dose can be derived from measurements of these parameters. In this case, it is not necessary to directly measure the DUV energy.

[0069] As mentioned above, K can be a calibration parameter, that is, a parameter measured during the calibration process. The calibration process can be as follows: Figure 7 The process is shown. In Figure 7 In the method shown, in step S300, a wafer with a targeting line or contact hole structure is exposed while measuring the EUV pulse energy and DUV pulse energy. The exposed wafer is processed in step S310. After processing the wafer, in step S340, the CD (cathode) as a function of wafer position can be measured and then mapped to the timing of the exposure and the timing of the EUV and DUV pulse energies. In step S350, a mathematical fit, such as linear fitting, can be applied to the measurements of CD, EUV energy, and DUV energy, for example using the modeling discussed above regarding effective dose, to obtain a value for K. Experimental designs with multiple wafer exposures can be used to evaluate factors controlling the value of K to offset contributions from time-dependent contributors to CD drift (e.g., mirror heating, process effects, etc.) to the calibration process.

[0070] As mentioned above, the relative sensitivity of a resist to non-EUV and EUV radiation can depend on the type of resist. The calibration process described above provides the ability to mitigate the effects of wavelength-dependent resist sensitivity by selecting appropriate calibration parameters.

[0071] The software functionality of a computer system involves programming, which includes executable code that can be used to implement the methods described above. The software code can be executed by a general-purpose computer. In operation, the code and possibly related data records are stored in a general-purpose computer platform. However, at other times, the software can be stored in other locations and / or delivered for loading into a suitable general-purpose computer system. Therefore, the embodiments described above relate to one or more software products in the form of one or more code modules carried on at least one machine-readable medium. Execution of such code by the processor of the computer system enables the platform to implement cataloging and / or software download functionality substantially in the manner described and illustrated in the embodiments discussed herein.

[0072] Computer-readable media may be located in the scanner section of a lithography apparatus, or in the source section of a lithography apparatus, or may be distributed among several systems of the lithography apparatus. Computer-readable media may be portable media.

[0073] As used herein, terms such as "computer or machine-readable medium" refer to any medium that participates in providing instructions to a processor for execution. Such media can take many forms, including, but not limited to, non-volatile media, volatile media, and transmission media. Non-volatile media include, for example, optical discs or disks, any storage device in any computer operating as one of the server platforms described above. Volatile media include dynamic memory, such as the main memory of such a computer platform. Physical transmission media include coaxial cables; copper wires and optical fibers, including lines that contain buses within a computer system. Carrier transmission media can take the form of electrical or electromagnetic signals, or sound or light waves, such as those generated during radio frequency (RF) and infrared (IR) data communications. Therefore, common forms of computer-readable media include, for example: floppy disks, flexible disks, hard disks, magnetic tapes, any other magnetic media, CD-ROMs, DVDs, any other optical media, less commonly used media (such as punched cards, paper tape, any other physical media with a perforated pattern), RAM, PROMs and EPROMs, FLASH-EPROMs, any other memory chips or cartridges, carrier waves for transmitting data or instructions, cables or links for transmitting such carrier waves, or any other media from which a computer can read programming code and / or data. Many of these forms of computer-readable media may involve carrying one or more sequences of one or more instructions to a processor for execution.

[0074] While specific reference may be made herein to the use of lithography equipment in IC manufacturing, it should be understood that the lithography equipment described herein may have other applications, such as the fabrication of integrated optical systems, the guiding and detection of patterns for magnetic domain memory, flat panel displays, liquid crystal displays (LCDs), thin-film magnetic heads, etc. Those skilled in the art will understand that, in the context of such alternative applications, any use of the terms “wafer” or “bare die” herein may be considered synonymous with the more general terms “substrate” or “target portion,” respectively. The substrate mentioned herein may be processed before or after exposure in, for example, in a track (a tool typically used to apply a resist layer to the substrate and develop the exposed resist), a measurement tool, and / or an inspection tool. Where applicable, the disclosure herein may be applied to such and other substrate processing tools. Furthermore, for example, to produce multilayer ICs, the substrate may be processed more than once, such that the term “substrate” as used herein may also refer to a substrate that already contains multiple processed layers.

[0075] While specific embodiments of the invention have been described above, it should be understood that the invention can be practiced in ways other than those described. The above description is intended to illustrate and not limit. Therefore, it will be apparent to those skilled in the art that modifications can be made to the described invention without departing from the scope of the appended claims.

[0076] It should be understood that the Detailed Description section, rather than the Summary and Abstract section, is intended to interpret the claims. The Summary and Abstract section may set forth one or more, but not all, exemplary embodiments of the invention as contemplated by the inventors, and is therefore not intended to limit the invention and the appended claims in any way.

[0077] The invention has been described above using functional building blocks that illustrate the implementation of specific functions and their relationships. For ease of description, the boundaries of these functional building blocks are arbitrarily defined herein. Alternative boundaries can be defined as long as the specified functions and their relationships are properly executed.

[0078] Various references to signals and operations on those signals are illustrative only; it should be understood that the signals can be analog or digital, electrical or wireless. Operations on those signals (such as addition and multiplication) presuppose operations applied to the information carried by those signals.

[0079] The above description of specific embodiments will fully reveal the general nature of the invention, enabling others to easily modify and / or adapt various applications of such specific embodiments without departing from the general conception of the invention by applying knowledge of the art. Therefore, based on the teachings and guidance given herein, such modifications and adjustments are intended to fall within the meaning and scope of equivalents of the disclosed embodiments. It should be understood that the wording or terminology used herein is for descriptive purposes and not for limitation, and that the terminology or terminology of this specification should be interpreted by those skilled in the art based on the teachings and guidance.

[0080] Other aspects of the invention are set forth in the following numbered clauses.

[0081] 1. A photolithography apparatus, comprising:

[0082] A conditioning system is configured to condition a radiation beam, the radiation beam comprising both EUV and non-EUV radiation; and

[0083] A controller adapted to control the radiation dose delivered to the substrate by the conditioning system based at least in part on the ratio of the energy of the non-EUV radiation to the energy of the EUV radiation.

[0084] 2. The lithography apparatus according to Clause 1, wherein the non-EUV radiation is DUV radiation, and the controller is adapted to control the radiation dose delivered to the substrate by the conditioning system based at least in part on the ratio of the energy magnitude of the DUV radiation to the energy magnitude of the EUV radiation.

[0085] 3. The lithography apparatus according to Clause 2, comprising at least one sensor arranged to measure the energy magnitude of the DUV radiation.

[0086] 4. The lithography apparatus according to Clause 3, wherein the at least one sensor is positioned to measure the magnitude of the energy of the DUV radiation at the substrate.

[0087] 5. The lithography apparatus according to Clause 3, wherein the at least one sensor is positioned to measure the magnitude of the energy of the DUV radiation at the conditioning system.

[0088] 6. The lithography apparatus according to Clause 5, wherein the lithography apparatus includes an irradiator, and wherein the conditioning system is included in the irradiator.

[0089] 7. The lithography apparatus according to Clause 5, wherein the lithography apparatus is a radiation source, and wherein the conditioning system is included in the radiation source.

[0090] 8. The lithography apparatus according to Clause 2 further includes a module configured to determine the energy magnitude of the DUV radiation based on a plurality of operating parameters of the source.

[0091] 9. The lithography apparatus according to Clause 2, wherein the controller is adapted to control the radiation dose delivered to the substrate by the conditioning system based at least in part on the product of the ratio and the calibration factor.

[0092] 10. A photolithography apparatus, comprising:

[0093] A conditioning system is configured to condition a radiation beam, the radiation beam comprising both EUV radiation and non-EUV radiation;

[0094] The first module is configured to generate a first signal indicating the energy magnitude of the EUV radiation;

[0095] The second module is configured to generate a second signal indicating the energy magnitude of the non-EUV radiation.

[0096] The third module is configured to multiply the second signal by a calibration factor to obtain a third signal;

[0097] The fourth module is configured to add the first signal and the third signal to obtain a fourth signal; and

[0098] A controller is arranged to receive the fourth signal and is adapted to control the radiation dose delivered to the substrate by the radiation beam based at least in part on the sum of the product of the energy magnitude of the non-EUV radiation and a calibration factor and the energy magnitude of the EUV radiation.

[0099] 11. The lithography apparatus according to Clause 10, wherein the non-EUV radiation is DUV radiation, and the controller is adapted to control the dose of radiation delivered to the substrate by the conditioning system based at least in part on the sum of the product of the energy magnitude of the DUV radiation and a calibration factor and the energy magnitude of the EUV radiation.

[0100] 12. The lithography apparatus according to Clause 10, wherein the second module includes at least one sensor arranged to measure the energy magnitude of the non-EUV radiation.

[0101] 13. The lithography apparatus according to Clause 12, wherein the at least one sensor is positioned to measure the energy of the non-EUV radiation at the substrate.

[0102] 14. The lithography apparatus according to Clause 12, wherein the at least one sensor is positioned to measure the energy of the non-EUV radiation at the conditioning system.

[0103] 15. The lithography apparatus according to Clause 10, wherein the second module is configured to infer the magnitude of DUV radiation from a plurality of operating parameters of the source.

[0104] 16. A method of manufacturing a device, comprising:

[0105] Generates a radiation beam that includes both EUV and non-EUV radiation; and

[0106] The radiation dose delivered to the substrate by the radiation beam is controlled at least in part based on the ratio of the energy of the non-EUV radiation to the energy of the EUV radiation.

[0107] 17. The method according to Clause 16, wherein the non-EUV radiation is DUV radiation, and controlling the radiation dose delivered to the substrate by the radiation beam based at least in part on the ratio of the energy magnitude of the non-EUV radiation to the energy magnitude of the EUV radiation comprises: controlling the radiation dose delivered to the substrate by the radiation beam based at least in part on the ratio of the energy magnitude of the DUV radiation to the energy magnitude of the EUV radiation.

[0108] 18. The method according to Clause 16 includes sensing the energy magnitude of the DUV radiation.

[0109] 19. The method according to Clause 18, wherein sensing the energy magnitude of the DUV radiation includes measuring the energy magnitude of the DUV radiation at the substrate.

[0110] 20. The method according to Clause 18, wherein sensing the energy magnitude of the DUV radiation includes measuring the energy magnitude of the DUV radiation at the conditioning system.

[0111] 21. The method according to Clause 16 further includes determining the energy magnitude of the DUV radiation based on a plurality of operating parameters of the source.

[0112] 22. The method according to Clause 16, wherein controlling the radiation dose delivered to the substrate by the radiation beam, based at least in part on the ratio of the energy magnitude of the DUV radiation to the energy magnitude of the EUV radiation, is performed at least in part on the product of the ratio and a calibration factor.

[0113] 23. A method of manufacturing a device, comprising:

[0114] A radiation source is used to generate a radiation beam, which includes EUV radiation and non-EUV radiation;

[0115] Generate a first signal representing the energy magnitude of the EUV radiation;

[0116] A second signal indicating the energy magnitude of the non-EUV radiation is generated;

[0117] The second signal is multiplied by a calibration factor to obtain the third signal;

[0118] The first signal and the third signal are added together to obtain the fourth signal; and

[0119] The fourth signal is provided to a dose controller, which controls the dose of radiation delivered to the substrate by the radiation beam based at least in part on the sum of the product of the energy magnitude of the non-EUV radiation and a calibration factor and the energy magnitude of the EUV radiation.

[0120] 24. The method according to Clause 23, wherein the non-EUV radiation is DUV radiation, and the dose controller controls the dose of radiation delivered to the substrate by the conditioning system based at least in part on the sum of the product of the energy magnitude of the DUV radiation and a calibration factor and the energy magnitude of the EUV radiation.

[0121] 25. The method described under Clause 23 includes sensing the energy magnitude of the non-EUV radiation.

[0122] 26. The method according to Clause 25, wherein sensing the energy magnitude of the non-EUV radiation comprises: measuring the energy magnitude of the non-EUV radiation at the substrate.

[0123] 27. The method according to Clause 25, wherein sensing the energy magnitude of the non-EUV radiation comprises: measuring the energy magnitude of the non-EUV radiation at the conditioning system.

[0124] 28. The method according to Clause 25, wherein generating a second signal indicating the energy magnitude of the non-EUV radiation comprises: determining the magnitude of the non-EUV radiation based on a plurality of operating parameters of the source.

[0125] 29. A method comprising:

[0126] Receive a first signal indicating the power of in-band EUV radiation in a radiation beam that includes EUV radiation;

[0127] Receive a second signal indicating the power of out-of-band radiation in the radiation beam;

[0128] Generate a third signal, wherein the third signal is based on the first signal and the second signal; and

[0129] The third signal is provided to a dose controller, which is configured to control the power of the radiation beam at least in part based on the third signal.

[0130] 30. The method according to Clause 29, wherein the second signal is based on a measurement of the combined power of the radiation beam, wherein the combined power includes the power of in-band EUV radiation in the radiation beam and the power of out-of-band radiation in the radiation beam.

[0131] 31. A tangible, non-transient computer-readable medium having instructions encoded thereon, the instructions being executable by a processor to perform a method, the method comprising:

[0132] Receive a first signal indicating the power of in-band EUV radiation in a radiation beam that includes EUV radiation;

[0133] Receive a second signal indicating the power of out-of-band radiation in the radiation beam;

[0134] Generate a third signal, wherein the third signal is based on the first signal and the second signal; and

[0135] The third signal is provided to a dose controller, which is configured to control the power of the radiation beam at least in part based on the third signal.

[0136] The breadth and scope of this invention should not be limited by any of the exemplary embodiments described above, but should be defined only by the appended claims and their equivalents.

Claims

1. A photolithography apparatus, comprising: A conditioning system is configured to condition a radiation beam, the radiation beam comprising both EUV radiation and non-EUV radiation; as well as A controller is adapted to control the radiation dose delivered to the substrate by the modulation system based at least in part on the ratio of the energy of the non-EUV radiation to the energy of the EUV radiation. The controller is adapted to control the radiation dose delivered to the substrate by the conditioning system based at least in part on the product of the ratio and the calibration factor.

2. The lithography apparatus of claim 1, wherein the non-EUV radiation is DUV radiation, and the ratio is the ratio of the energy of the DUV radiation to the energy of the EUV radiation.

3. The lithography apparatus of claim 2, comprising at least one sensor arranged to measure the energy of the DUV radiation.

4. The lithography apparatus of claim 3, wherein the at least one sensor is positioned to measure the energy of the DUV radiation at the substrate.

5. The lithography apparatus of claim 3, wherein the at least one sensor is positioned to measure the energy magnitude of the DUV radiation at the conditioning system.

6. The lithography apparatus of claim 5, wherein the lithography apparatus includes an irradiator, and wherein the adjustment system is included in the irradiator.

7. The lithography apparatus of claim 5, wherein the lithography apparatus is a radiation source, and wherein the conditioning system is included in the radiation source.

8. The lithography apparatus of claim 7 further includes a module configured to determine the energy level of the DUV radiation based on a plurality of operating parameters of the radiation source.

9. A photolithography apparatus, comprising: A conditioning system is configured to condition a radiation beam, the radiation beam comprising both EUV radiation and non-EUV radiation; The first module is configured to generate a first signal indicating the energy magnitude of the EUV radiation; The second module is configured to generate a second signal indicating the energy magnitude of the non-EUV radiation. The third module is configured to multiply the second signal by a calibration factor to obtain a third signal; The fourth module is configured to add the first signal and the third signal to obtain a fourth signal; as well as The controller is configured to receive the fourth signal and is adapted to control the radiation dose delivered to the substrate by the radiation beam based at least in part on the sum of the product of the energy magnitude of the non-EUV radiation and the calibration factor and the energy magnitude of the EUV radiation.

10. The lithography apparatus of claim 9, wherein the non-EUV radiation is DUV radiation, and the controller is adapted to control the radiation dose delivered to the substrate by the conditioning system based at least in part on the sum of the product of the energy magnitude of the DUV radiation and a calibration factor and the energy magnitude of the EUV radiation.

11. The lithography apparatus of claim 9, wherein the second module includes at least one sensor arranged to measure the energy of the non-EUV radiation.

12. The lithography apparatus of claim 11, wherein the at least one sensor is positioned to measure the energy magnitude of the non-EUV radiation at the substrate.

13. The lithography apparatus of claim 11, wherein the at least one sensor is positioned to measure the energy magnitude of the non-EUV radiation at the conditioning system.

14. The lithography apparatus of claim 9, wherein the second module is configured to infer the magnitude of DUV radiation based on a plurality of operating parameters of the radiation source.

15. A method of manufacturing a device, comprising: It generates a radiation beam that includes both EUV and non-EUV radiation; as well as The radiation dose delivered to the substrate by the radiation beam is controlled at least in part based on the ratio of the energy of the non-EUV radiation to the energy of the EUV radiation. The radiation dose delivered to the substrate is controlled by adjusting the system, based at least in part on the product of the ratio and the calibration factor.

16. The method of claim 15, wherein the non-EUV radiation is DUV radiation, and the ratio is the ratio of the energy magnitude of the DUV radiation to the energy magnitude of the EUV radiation.

17. The method of claim 16, further comprising sensing the energy magnitude of the DUV radiation.

18. The method of claim 17, wherein sensing the energy magnitude of the DUV radiation comprises: The energy level of the DUV radiation at the substrate is measured.

19. The method of claim 17, wherein sensing the energy magnitude of the DUV radiation comprises: The energy level of the DUV radiation at the conditioning system is measured.

20. The method of claim 16, further comprising determining the energy magnitude of the DUV radiation based on a plurality of operating parameters of the radiation source.

21. A method of manufacturing a device, comprising: A radiation source is used to generate a radiation beam, which includes EUV radiation and non-EUV radiation; Generate a first signal representing the energy magnitude of the EUV radiation; A second signal indicating the energy magnitude of the non-EUV radiation is generated; The second signal is multiplied by a calibration factor to obtain the third signal; The first signal and the third signal are added together to obtain the fourth signal; as well as The fourth signal is provided to a dose controller, which controls the radiation dose delivered to the substrate by the radiation beam based at least in part on the sum of the product of the energy magnitude of the non-EUV radiation and a calibration factor and the energy magnitude of the EUV radiation.

22. The method of claim 21, wherein the non-EUV radiation is DUV radiation, and the dose controller controls the dose of radiation delivered to the substrate by the conditioning system based at least in part on the sum of the product of the energy magnitude of the DUV radiation and a calibration factor and the energy magnitude of the EUV radiation.

23. The method of claim 21, comprising sensing the energy magnitude of the non-EUV radiation.

24. The method of claim 23, wherein sensing the magnitude of the energy of the non-EUV radiation comprises: The energy level of the non-EUV radiation at the substrate is measured.

25. The method of claim 23, wherein sensing the energy magnitude of the non-EUV radiation comprises: The energy level of the non-EUV radiation at the conditioning system is measured.

26. The method of claim 23, wherein generating a second signal indicating the energy magnitude of the non-EUV radiation comprises: The magnitude of the non-EUV radiation is determined based on multiple operating parameters of the radiation source.

27. A method comprising: Receive a first signal indicating the power of in-band EUV radiation in a radiation beam that includes EUV radiation; Receive a second signal indicating the power of out-of-band radiation in the radiation beam; A third signal is generated, wherein the third signal is based at least in part on the sum of the product of the energy magnitude of the out-of-band EUV radiation and the calibration factor and the energy magnitude of the in-band EUV radiation; as well as The third signal is provided to a dose controller, which is configured to control the power of the radiation beam at least in part based on the third signal.

28. The method of claim 27, wherein the second signal is based on a measurement of the combined power of the radiation beam, wherein the combined power includes the power of in-band EUV radiation in the radiation beam and the power of out-of-band radiation in the radiation beam.

29. A tangible, non-transient computer-readable medium having instructions encoded thereon, the instructions being executable by a processor to perform a method, the method comprising: Receive a first signal indicating the power of in-band EUV radiation in a radiation beam that includes EUV radiation; Receive a second signal indicating the power of out-of-band radiation in the radiation beam; A third signal is generated, wherein the third signal is based at least in part on the sum of the product of the energy magnitude of the out-of-band EUV radiation and the calibration factor and the energy magnitude of the in-band EUV radiation; as well as The third signal is provided to a dose controller, which is configured to control the power of the radiation beam at least in part based on the third signal.

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