Forming multiple aerial images in single lithography exposure pass

Abstract

To form multiple aerial images in a single lithography exposure pass.SOLUTION: A set of pulses of light in a light beam is passed through a mask toward a wafer during a single exposure pass; at least a first aerial image and a second aerial image on the wafer based on pulses of light in the set of pulses that pass through the mask is generated during a single exposure pass, the first aerial image being at a first plane on the wafer, and the second aerial image being at a second plane on the wafer, where the first plane and the second plane are spatially distinct from each other and separated from each other by a separation distance along the direction of propagation; and a three-dimensional semiconductor component is formed.SELECTED DRAWING: Figure 1A

Description

[Technical field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to U.S. Provisional Patent Application No. 62 / 574,628, filed October 19, 2017, which is incorporated by reference in its entirety herein.

[0002]

[0002] This disclosure relates to forming multiple aerial images in a single lithographic exposure pass. The techniques discussed below can be used, for example, to form three-dimensional semiconductor components. [Background technology]

[0003]

[0003] Photolithography is the process of patterning semiconductor circuits onto a substrate such as a silicon wafer. A photolithography light source provides the deep ultraviolet (DUV) light used to expose photoresist on the wafer. DUV light for photolithography is generated by an excimer light source. Often the light source is a laser source and the pulsed light beam is a pulsed laser beam. The light beam passes through a beam delivery unit, a reticle or mask, and is then projected onto a prepared silicon wafer. In this way the chip design is patterned onto the photoresist, which is then etched and cleaned, and the process is repeated. Summary of the Invention

[0004]

[0004] In one general aspect, a method for forming a three-dimensional semiconductor component using a photolithography system includes directing a pulsed light beam comprising a plurality of light pulses along a propagation direction toward a mask; directing a set of light pulses of the light beam through the mask toward a wafer during a single exposure pass; generating at least a first aerial image and a second aerial image on the wafer during the single exposure pass based on the light pulses in the set of pulses passing through the mask, wherein the first aerial image is in a first plane on the wafer and the second aerial image is in a second plane on the wafer, the first plane and the second plane being spatially distinct from each other and separated from each other along the propagation direction by a separation distance; and forming the three-dimensional semiconductor component based on an interaction of the light of the first aerial image with a material of a first portion of the wafer and an interaction of the light of the second aerial image with a material of a second portion of the wafer. At least one of the pulses in the pulse set has a first primary wavelength and at least one of the other pulses in the pulse set has a second primary wavelength that is different from the first primary wavelength, such that a separation distance is formed during a single exposure pass based on the difference between the first primary wavelength and the second primary wavelength.

[0005] Implementations may include one or more of the following features: At least one of the pulses in the set of pulses that passes through the mask during a single exposure pass may have two or more primary wavelengths of light.

[0006]

[0006] Each primary wavelength may be separated from the nearest other primary wavelength by a spectral separation of 200 femtometers (fm) to 500 picometers (pm).

[0007] The separation distance between the first aerial image and the second aerial image can vary during a single exposure pass.

[0008]

[0008] The single exposure pass may be a first exposure pass, and the method may further include directing a second set of light pulses of the light beam through the mask to the wafer during a second exposure pass and after the first exposure pass is completed. A separation distance between the first aerial image and the second aerial image is different during the first exposure pass and the second exposure pass.

[0009]

[0009] The separation distance between the first and second aerial images can be set prior to the single exposure pass, and in some implementations, the separation distance does not change during the single exposure pass. The separation distance between the first and second aerial images can be set to accommodate one or more features of the photolithography system.

[0010]

[0010] The pulse set includes a first group of light pulses and a second group of light pulses, each pulse of the first group of light pulses having a first primary wavelength and each pulse of the second group of light pulses having a second primary wavelength, and the method further includes controlling an amount of light of the first aerial image by controlling a characteristic of the first group of pulses, and controlling an amount of light of the second aerial image by controlling a characteristic of the second group of pulses. The characteristic of the first group may be a number of pulses of the first group, and the characteristic of the second group may be a number of pulses of the second group. Controlling the number of pulses of the first group may include determining a first number of pulses to include in the first group of pulses before the single exposure pass begins, and controlling the second number of pulses may include determining a second number of pulses to include in the second group of pulses before the single exposure pass. The first group of pulses and the second group of pulses may include all pulses passing through the mask in the single exposure pass. Determining the first number of pulses and the second number of pulses can include one or more of: (a) receiving input from an operator and (b) accessing predefined settings associated with the photolithography system. The characteristics of the first group of pulses can include an intensity of each pulse in the first group, and the characteristics of the second group of pulses can include an intensity of each pulse in the second group.

[0011]

[0011] The first plane on the wafer and the second plane on the wafer may be planes that are substantially perpendicular to the direction of propagation.

[0012]

[0012] In some implementations, a first three-dimensional semiconductor feature is formed in a first plane and a second three-dimensional semiconductor feature is formed in a second plane, the first and second features being separated from each other by sidewalls extending substantially parallel to the propagation direction.

[0013] The three-dimensional semiconductor component may be a three-dimensional NAND flash memory component.

[0014]

[0014] The first plane may correspond to a first focal plane and the second plane may correspond to a second focal plane, and a separation distance between the first plane and the second plane is based on one or more wavelength differences of the light pulses passing through the mask or wavelength differences between individual pulses of the pulse set.

[0015]

[0015] In another general aspect, a photolithography system includes a lithography scanner apparatus having a light source, a mask positioned to interact with a pulsed light beam from the light source, and a wafer holder, and a control system coupled to the light source, wherein the control system is configured to cause the light source to emit a pulsed light beam toward the lithography scanner apparatus during a single exposure pass, during which at least a first aerial image and a second aerial image are formed on a wafer supported by the wafer holder based on a set of light pulses passing through the mask along a propagation direction, the first aerial image being in a first plane on the wafer and the second aerial image being in a second plane on the wafer, the first plane and the second plane being spatially distinct from each other and separated from each other by a separation distance along the propagation direction, and a three-dimensional semiconductor component is formed based on interaction of the light of the first aerial image with a material of a first portion of the wafer and interaction of the light of the second aerial image with a material of a second portion of the wafer. At least one of the pulses in the pulse set has a first primary wavelength and at least one other pulse in the pulse set has a second primary wavelength different from the first primary wavelength, and a separation distance between the first aerial image and the second aerial image is based on the difference between the first primary wavelength and the second primary wavelength.

[0016]

[0016] Implementations may include one or more of the following features: The control system includes a computer-readable storage medium, one or more electronic processors coupled to the computer-readable storage medium, and an input / output interface, and a recipe associated with the photolithography system is stored in the computer-readable storage medium. The recipe may define a separation distance. The recipe defines a separation distance on a wafer-by-wafer or lot-by-lot basis. The light source may include a krypton fluoride (KrF) gain medium or an argon fluoride (ArF) gain medium.

[0017]

[0017] Implementations of any of the techniques described herein above may include a process, an apparatus, a control system, instructions stored on a non-transitory machine-readable computer medium, and / or a method. Details of one or more implementations are set forth in the accompanying drawings and the description below. Other features will be apparent from the description and drawings, and from the claims. [Brief description of the drawings]

[0018] [Figure 1A]

[0018] FIG. 1 is a block diagram of an exemplary implementation of a photolithography system. [Figure 1B]

[0019] FIG. 1B is a block diagram of an example implementation of an optical system for the photolithography system of FIG. 1A. [Figure 1C]

[0020] 1B is a cross-sectional view of an exemplary wafer exposed by the photolithography system of FIG. 1A. [Figure 2A]

[0021] FIG. 2 is a block diagram of another exemplary implementation of a photolithography system. [Figure 2B]

[0022] FIG. 2 is a block diagram of an example implementation of a spectral feature selection module that may be used in a photolithography system. [Figure 2C]

[0023] FIG. 2 is a block diagram of an example implementation of a line narrowing module. [Figure 3A]

[0024] 1 is a plot of data relating to the generation of pulses and / or bursts of pulses in a light source. [Figure 3B] 1 is a plot of data relating to the generation of pulses and / or bursts of pulses in a light source. [Figure 4]

[0025] FIG. 2 is a block diagram of another exemplary implementation of a photolithography system. [Diagram 5]

[0026] 1 is a flowchart of an exemplary process for forming a three-dimensional semiconductor component. [Figure 6A]

[0027] 1 illustrates an exemplary optical spectrum of a single light pulse. [Figure 6B]

[0027] An exemplary optical spectrum of a single light pulse is shown. [Figure 7]

[0028] 4 shows an exemplary average optical spectrum of a single exposure pass. [Figure 8A]

[0029] 1 illustrates a vertical cross-sectional view of an exemplary wafer. [Figure 8B]

[0029] A horizontal cross-sectional view of an exemplary wafer is shown. [Figure 9A]

[0030] 1 illustrates a vertical cross-sectional view of an exemplary three-dimensional semiconductor component. [Figure 9B]

[0030] A horizontal cross-sectional view of an exemplary three-dimensional semiconductor component is shown. [Figure 10A]

[0031] 1 shows exemplary simulated data. [Figure 10B]

[0031] Exemplary simulated data is shown. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0019]

[0032] Contemplated herein is a technique for forming two or more aerial images, each at a different plane, in a single lithographic pass and using the aerial images to form three-dimensional semiconductor components.

[0020]

[0033] 1A, a photolithography system 100 includes a light source 105 that provides a light beam 160 to a lithography exposure apparatus 169 that processes a wafer 170 supported by a wafer holder or stage 171. The light beam 160 is a pulsed light beam that includes pulses of light that are separated in time from one another. The lithography exposure apparatus 169 includes a projection optical system 175 through which the light beam 160 passes before reaching the wafer 170, and a metrology system 172. The metrology system 172 can include, for example, a camera or other device that can capture an image of the wafer 170 and / or the light beam 160 at the wafer 170, or a light detector that can collect data describing characteristics of the light beam 160, such as the intensity of the light beam 160 at the wafer 170 in the xy plane. The lithography exposure apparatus 169 can be an immersion system or a dry system. The photolithography system 100 may also include a control system 150 that controls the light source 105 and / or the lithography exposure device 169 .

[0021]

[0034] For example, microelectronic features are formed on wafer 170 by exposing a layer of radiation-sensitive photoresist material on wafer 170 to light beam 160. Referring again to FIG. 1B, projection optical system 175 includes a slit 176, a mask 174, and a projection objective including a lens 177. Light beam 160 enters optical system 175 and impinges on slit 176, through which at least a portion of beam 160 passes. In the example of FIGS. 1A and 1B, slit 176 is rectangular and shapes light beam 160 into an elongated rectangular light beam. A pattern is formed on mask 174, and the pattern determines which portions of the shaped light beam are transmitted by mask 174 and which portions are blocked by mask 174. The design of the pattern is determined by the particular microelectronic circuit design to be formed on wafer 170.

[0022]

[0035] The shaped light beam interacts with mask 174. The portion of the shaped light beam transmitted by mask 174 passes through (and may be focused by) projection lens 177, exposing wafer 170. The portion of the shaped light beam transmitted by mask 174 forms an aerial image in the xy plane of wafer 170. The aerial image is the intensity pattern formed by the light that reaches wafer 170 after interacting with mask 174. The aerial image is at wafer 170 and extends generally in the xy plane.

[0023]

[0036] System 100 can form multiple aerial images during a single exposure pass, each at a different spatial location along the z-axis of wafer 170. Also referring to FIG. 1C, which shows a cross-sectional view of wafer 170 in the yz-plane, projection optical system 175 forms two aerial images 173a, 173b at different planes along the z-axis in a single exposure pass. As discussed in more detail below, each of aerial images 173a, 173b is formed from light having a different primary wavelength.

[0024]

[0037] The position of the aerial image along the z-axis depends on the properties of optical system 175 (including projection lens 177 and mask 174) and the wavelength of light beam 160. The focal position of lens 177 depends on the wavelength of light incident on lens 177. Thus, by varying or otherwise controlling the wavelength of light beam 160, the position of the aerial image can be controlled. By providing pulses having different primary wavelengths of light during a single exposure pass, multiple (two or more) aerial images, each at a different position along the z-axis, can be formed in a single exposure pass without moving optical system 175 (or any component of optical system 175) and wafer 170 relative to each other along the z-axis.

[0025]

[0038] In the example of FIG. 1A, light passing through mask 174 is focused to a focal plane by projection lens 177. The focal plane of projection lens 177 is between projection lens 177 and wafer stage 171, and the location of the focal plane along the z-axis depends on the properties of optical system 175 and the wavelength of light beam 160. Aerial images 173a, 173b are formed from light having different wavelengths and therefore are at different locations on wafer 170. Aerial images 173a, 173b are separated from each other along the z-axis by a separation distance 179. Separation distance 179 depends on the difference between the wavelength of the light forming aerial image 173a and the wavelength of the light forming aerial image 173b.

[0026]

[0039] The wafer stage 171 and mask 174 (or other components of the optical system 175) typically move relative to one another in the x, y, and z directions during scanning for normal performance correction and operation, and this motion can be used to achieve, for example, basic leveling, correction of lens distortion, and correction of stage positioning errors. This relative motion is referred to as incidental motion motion. However, in the system of FIG. 1A, the relative motion of the wafer stage 171 and the optical system 175 is not used to create the separation distance 179. Instead, the separation distance 179 is created by being able to control the primary wavelength of the pulses passing through the mask 174 during an exposure pass. Thus, the separation distance 179 is not created by simply moving the optical system 175 and the wafer 170 relative to one another along the z axis, as in some conventional systems. Also, the aerial images 173a and 173b are both present on the wafer 170 during the same exposure pass. In other words, system 100 does not require that aerial image 173a be formed in a first exposure pass and aerial image 173b be formed in a subsequent second exposure pass.

[0027]

[0040] The light in the first aerial image 173a interacts with the wafer at portion 178a, and the light in the second aerial image 173b interacts with the wafer at portion 178b. These interactions can form electronic features or other physical features, such as openings or holes, on the wafer 170. Because the aerial images 173a, 173b are at different planes along the z-axis, the aerial images 173a, 173b can be used to form three-dimensional features on the wafer 170. For example, the aerial image 173a can be used to form a peripheral region, and the aerial image 173b can be used to form a channel, trench, or depression that is at a different location along the z-axis. Thus, the techniques discussed herein can be used to form three-dimensional semiconductor components, such as three-dimensional NAND flash memory components.

[0028]

[0041] Before considering further details regarding forming multiple aerial images in a single exposure pass, exemplary implementations of light source 105 and photolithography system 100 are discussed with reference to Figures 2A-2C, 3A-3C, and 4.

[0029]

[0042] Referring to FIG. 2A, a block diagram of a photolithography system 200 is shown. The system 200 is an exemplary implementation of the system 100 (FIG. 1A). For example, in the photolithography system 200, a light source 205 is used as the light source 105 (FIG. 1A). The light source 205 generates a pulsed light beam 260, which is provided to a lithography exposure apparatus 169. The light source 205 may be, for example, an excimer light source that outputs the pulsed light beam 260, which may be a laser beam. Once the pulsed light beam 260 enters the lithography exposure apparatus 169, the pulsed light beam 260 is directed through a projection optical system 175 and projected onto the wafer 170. In this manner, one or more microelectronic features are patterned on the photoresist on the wafer 170, which is then developed and cleaned prior to a subsequent process step, and the process repeats. Photolithography system 200 also includes a control system 250, which in the example of Figure 2A is connected to components of light source 205 as well as lithography exposure apparatus 169 for controlling various operations of system 200. Control system 250 is an exemplary implementation of control system 250 of Figure 1A.

[0030]

[0043] 2A, the light source 205 is a two-stage laser system with a master oscillator (MO) 212 that provides a seed light beam 224 to a power amplifier (PA) 230. The MO 212 and PA 230 may be considered subsystems of the light source 205, or systems that are part of the light source 205. The power amplifier 230 receives the seed light beam 224 from the master oscillator 212 and amplifies the seed light beam 224 to generate a light beam 260 for use in the lithography exposure tool 169. For example, the master oscillator 212 may emit a pulsed seed light beam with a seed pulse energy of about 1 millijoule (mJ) per pulse, and these seed pulses may be amplified by the power amplifier 230 to about 10-15 mJ.

[0031]

[0044] The master oscillator 212 comprises a discharge chamber 240 having two elongated electrodes 217, a gain medium 219 which is a gas mixture, and a fan for circulating the gas between the electrodes 217. A resonator is formed between a line narrowing module 216 on one side of the discharge chamber 240 and an output coupler 218 on a second side of the discharge chamber 240. The line narrowing module 216 may comprise a diffractive optical component such as a grating that finely tunes the spectral output of the discharge chamber 240. Figures 2B and 2C provide further details about the line narrowing module 216.

[0032]

[0045] 2B is a block diagram of an example implementation of a spectral feature selection module 258 that includes one or more examples of the line narrowing module 216. The spectral feature selection module 258 couples to light propagating from the light source 205. In some implementations (e.g., shown in FIG. 2B ), the spectral feature selection module 258 receives light from the chamber 214 of the master oscillator 212 to enable fine tuning of spectral features, such as wavelength and bandwidth, within the master oscillator 212.

[0033]

[0046] The spectral feature selection module 258 may include a control module, such as a spectral feature control module 254, which includes electronic components in the form of any combination of firmware and software. The control module 254 is connected to one or more actuation systems, such as spectral feature actuation systems 255_1-255_n. Each of the actuation systems 255_1-255_n may comprise one or more actuators connected to respective optical features 256_1-256_n of the optical system 257. The optical features 256_1-256_n are configured to adjust the spectral features of the light beam 260 by adjusting certain characteristics of the generated light beam 260. The control module 254 receives control signals from the control system 250, which include specific commands to operate or control one or more of the actuation systems 255_1-255_n. The actuation systems 255_1-255_n may be selected and designed to work together, i.e., in concert, or the actuation systems 255_1-255_n may be configured to work individually. Additionally, each of the actuation systems 255_1 to 255_n may be optimized to handle a particular class of disturbance.

[0034]

[0047] Each of the optical features 256_1-256_n is optically coupled to the light beam 260 generated by the light source 105. The optical system 257 can be implemented as a line narrowing module 216C as shown in FIG. 2C. The line narrowing module includes a dispersive optical element, such as a reflective grating 291, as the optical features 256_1-256_n, and a refractive optical element, such as a prism 292, 293, 294, 295. One or more of the prisms 292, 293, 294, 295 may be rotatable. An example of this line narrowing module can be found in U.S. Application Serial No. 12 / 605,306, filed October 23, 2009, entitled SYSTEM METHOD AN APPARATUS FOR SELECTING AND CONTROLLING LIGHT SOURCE BANDWIDTH (the '306 application). The '306 application describes a line narrowing module that includes a beam expander (including one or more prisms 292, 293, 294, 295) and a dispersive element such as a grating 291. Not shown in Figure 2C are the actuation systems for each of the actuatable optical features such as the grating 291 and one or more of the prisms 292, 293, 294, 295.

[0035]

[0048] Each of the actuators of the actuation system 255_1-255_n is a mechanical device for moving or controlling a respective optical feature 256_1-256_n of the optical system 257. The actuators receive energy from the module 254 and convert the energy into some type of motion imparted to the optical features 256_1-256_n of the optical system 257. For example, the '306 application describes actuation systems such as force devices (for applying force to regions of the grating) and rotation stages for rotating one or more of the prisms of the beam expander. The actuation systems 255_1-255_n can include, for example, motors such as stepper motors, valves, pressure control devices, piezo devices, linear motors, hydraulic actuators, and / or voice coils.

[0036]

[0049] 2A , the master oscillator 212 also includes a line center analysis module 220 that receives the output light beam from the output coupler 218, and a beam combining optical system 222 that optionally resizes or shapes the output light beam to form a seed light beam 224. The line center analysis module 220 is a measurement system that may be used to measure or monitor the wavelength of the seed light beam 224. The line center analysis module 220 may be located elsewhere within the light source 205 or may be located at the output of the light source 205.

[0037]

[0050] The gas mixture used in the discharge chamber 240 may be any gas suitable for producing a light beam at the wavelength and bandwidth required for this application. In the case of an excimer source, the gas mixture may include noble gases, such as argon or krypton, halogens, such as fluorine or chlorine, and traces of xenon, other than the buffer gases helium and / or neon. Specific examples of gas mixtures include argon fluoride (ArF), which emits light at a wavelength of about 193 nm, krypton fluoride (KrF), which emits light at a wavelength of about 248 nm, or xenon chloride (XeCl), which emits light at a wavelength of about 351 nm. The excimer gain medium (gas mixture) is excited with a short (e.g., nanosecond) current pulse in a high-voltage discharge by applying a voltage to the elongated electrodes 217.

[0038]

[0051] The power amplifier 230 includes a beam combining optical system 232 that receives the seed light beam 224 from the master oscillator 212 and directs the light beam through a discharge chamber 240 to beam turning optics 248, which redirects or changes the seed light beam 224 so that it is transmitted back into the discharge chamber 240. The discharge chamber 240 includes a pair of elongated electrodes 241, a gain medium 219 which is a gas mixture, and a fan for circulating the gas mixture between the electrodes 241.

[0039]

[0052] The output light beam 260 is directed through a bandwidth analysis module 262 that can measure various parameters of the beam 260, such as bandwidth and wavelength. The output light beam 260 can also be directed through a beam generation system 263. The beam generation system 263 can include, for example, a pulse stretcher, where each pulse of the output light beam 260 is stretched in time, for example in an optical delay unit, to adjust the performance characteristics of the light beam impinging on the lithography exposure apparatus 169. The beam generation system 263 can also include other components that can act on the beam 260, such as reflective and / or refractive optical elements (such as lenses and mirrors), filters, and optical apertures (including automatic shutters).

[0040]

[0053] The photolithography system 200 also includes a control system 250. In the implementation shown in FIG. 2A, the control system 250 is connected to various components of the light source 205. For example, the control system 250 can control when the light source 205 emits a pulse of light or a burst of light pulses including one or more pulses of light by sending one or more signals to the light source 205. The control system 250 is also connected to the lithography exposure apparatus 169. Thus, the control system 250 can also control various aspects of the lithography exposure apparatus 169. For example, the control system 250 can control the exposure of the wafer 170 and thus can be used to control how electronic features are printed on the wafer 170. In some implementations, the control system 250 can control the scanning of the wafer 170 by controlling the movement of the slit 176 in the xy plane (FIG. 1B). The control system 250 can also exchange data with the metrology system 172 and / or the optical system 175.

[0041]

[0054] The lithography exposure apparatus 169 may also comprise, for example, temperature control devices (such as air conditioning and / or heating devices) and / or power supplies for various electrical components. The control system 250 may also control these components. In some implementations, the control system 250 is implemented to comprise two or more sub-control systems, with at least one sub-control system (a lithography controller) dedicated to controlling aspects of the lithography exposure apparatus 169. In these implementations, the control system 250 may be used to control aspects of the lithography exposure apparatus 169 instead of or in addition to using a lithography controller.

[0042]

[0055] The control system 250 comprises an electronic processor 251, electronic storage 252, and an I / O interface 253. The electronic processor 251 includes one or more processors suitable for executing a computer program, such as general purpose or special purpose microprocessors, and any one or more processors of any type of digital computer. Typically, an electronic processor receives instructions and data from a read-only memory, a random access memory, or both. The electronic processor 251 may be any type of electronic processor.

[0043]

[0056] Electronic storage 252 may be volatile memory, such as RAM, or non-volatile memory. In some implementations, electronic storage 252 comprises non-volatile and volatile parts or components. Electronic storage 252 may store data and information used in the operation of control system 250, components of control system 250, and / or systems controlled by control system 250. The information may be stored, for example, in a look-up table or database. For example, electronic storage 252 may store data indicative of values ​​of various characteristics of beam 260 under different operating conditions and performance scenarios.

[0044]

[0057] The electronic storage 252 may also store various recipes or process programs 259 that determine the parameters of the light beam 260 during use. For example, the electronic storage 252 may store a recipe that indicates the wavelength of each pulse in the light beam 260 for a particular exposure pass. The recipe may indicate different wavelengths for different exposure passes. The wavelength control techniques discussed below may be applied on a pulse-by-pulse basis. In other words, the wavelength components may be controlled for each individual pulse in an exposure pass to facilitate formation of an aerial image at a desired location along the z-axis.

[0045]

[0058] The electronic storage 252 may also store instructions, possibly computer programs, that, when executed, cause the processor 251 to communicate with the control system 250 , the optical system 205 , and / or components within the lithographic exposure apparatus 169 .

[0046]

[0059] I / O interface 253 is any type of electronic interface that allows control system 250 to receive and / or provide data and signals to an operator, optical system 205, lithography exposure apparatus 169, any component or system within optical system 205 and / or lithography exposure apparatus 169, and / or an automated process operating on another electronic device. For example, I / O interface 253 may include one or more of a visual display device, a keyboard, and a communications interface.

[0047]

[0060] Light beam 260 (and light beam 160) is a pulsed light beam and can include one or more bursts of pulses separated from one another in time. Each burst can include one or more pulses of light. In some implementations, a burst can include hundreds of pulses, for example 100-400 pulses. Figures 3A-3C provide an overview of the generation of pulses and bursts in light source 205. Figure 3A shows the amplitude of wafer exposure signal 300 as a function of time, Figure 3B shows the amplitude of gating signal 315 as a function of time, and Figure 3C shows the amplitude of a trigger signal as a function of time.

[0048]

[0061] The control system 250 can be configured to send a wafer exposure signal 300 to the light source 205 to control the light source 205 to generate the light beam 260. In the example shown in Figure 3A, the wafer exposure signal 300 has a high value 305 (e.g., 1) for a period 307 during which the light source 205 generates a burst of light pulses. In another situation, when the wafer 170 is not being exposed, the wafer exposure signal 300 has a low value 310 (e.g., 0).

[0049]

[0062] 3B, the light beam 260 is a pulsed light beam, the light beam 260 includes pulse bursts. The control system 250 also controls the duration and frequency of the pulse bursts by sending a gating signal 315 to the light source 205. The gating signal 315 has a high value 320 (e.g., 1) during the pulse bursts and a low value 325 (e.g., 0) during the time between successive bursts. In the example shown, the period during which the gating signal 315 has a high value is also the duration of a burst 316. The bursts are separated in time by the time interval between the bursts. During the time interval between the bursts, the lithography exposure apparatus 169 can position the next die on the wafer 170 for exposure.

[0050]

[0063] 3C, the control system 250 also controls the repetition rate of the pulses in each burst using a trigger signal 330. The trigger signal 330 includes triggers 340, one of which is provided to the light source 205 to cause the light source 205 to generate a light pulse. The control system 250 can send the trigger 340 to the light source 205 each time a pulse is to be generated. Thus, the repetition rate of the pulses generated by the light source 205 (the time between two successive pulses) can be set by the trigger signal 330.

[0051]

[0064] As described above, when the gain medium 219 is excited by applying a voltage to the electrode 217, the gain medium 219 emits light. When a voltage is applied to the electrode 217 in pulses, the light emitted from the medium 219 is also pulsed. Thus, the repetition rate of the pulsed light beam 260 is determined by the rate at which a voltage is applied to the electrode 217, and a light pulse is generated each time the voltage is applied. The light pulses propagate through the gain medium 219 and exit the chamber 214 through the output coupler 218. Thus, a pulse train is generated by the cyclically repeated application of a voltage to the electrode 217. The trigger signal 330 can be used, for example, to control the application of the voltage to the electrode 217 and the repetition rate of the pulses, which may be between about 500-6,000 Hz in most applications. In some implementations, the repetition rate may be greater than 6,000 Hz, for example 12,000 Hz or greater.

[0052]

[0065] Signals from the control system 250 can also be used to control electrodes 217, 241 in the master oscillator 212 and power amplifier 230, respectively, to control the pulse energy of the master oscillator 212 and power amplifier 230, respectively, and thus the energy of the light beam 260. There may be a delay between the signal provided to electrode 217 and the signal provided to electrode 241. The amount of delay may affect the properties of the pulsed light beam 260, such as the amount of coherence in the beam 260.

[0053]

[0066] The pulsed light beam 260 can have an average output power in the range of tens of watts, for example, from about 50 W to about 130 W. The irradiance (i.e., average power per unit area) of the light beam 260 at the output can be greater than 60 W / cm. 2 ~80W / cm 2 could reach.

[0054]

[0067] Also referring to FIG. 4, the wafer 170 is illuminated with a light beam 260. The lithography exposure apparatus 169 comprises an optical system 175 (FIGS. 1A and 1B). In the example of FIG. 4, the optical system 175 (not shown) comprises an illuminator system 429 with an objective 432. The objective 432 comprises a projection lens 177 (FIG. 1B) and enables image transfer from the mask 174 to the photoresist on the wafer 170. The illuminator system 429 adjusts the angular range of the light beam 260 that impinges on the mask 174. The illuminator system 429 can also equalize (uniformize) the intensity distribution of the light beam 260 in the xy plane across the mask 174.

[0055]

[0068] In some implementations, an immersion medium may be provided to cover the wafer 170. The immersion medium may be a liquid for immersion lithography (such as water). In other implementations where the lithography is dry, the immersion medium may be a gas, such as dry nitrogen, dry air, or clean air. In other implementations, the wafer 170 may be exposed inside a pressure-controlled environment (such as a vacuum or partial vacuum).

[0056]

[0069] During an exposure pass, a number N of pulses of light beam 260 illuminate the same area of ​​wafer 170, where N is any integer greater than 1. The number N of pulses of light beam 110 that illuminate the same area may be referred to as an exposure window or exposure pass 400. The size of window 400 may be controlled by slit 176. For example, slit 176 may comprise multiple blades that are movable to form an aperture in one shape and close the aperture in another shape. The size of window 400 may also be controlled by arranging the blades of slit 176 to form an aperture of a particular size.

[0057]

[0070] The N pulses also determine the illumination dose of the exposure pass. The illumination dose is the amount of optical energy delivered to the wafer during an exposure pass. Thus, the characteristics of the N pulses, such as the optical energy of each pulse, determine the illumination dose. Also, as will be discussed in more detail below, the N pulses can be used to determine the amount of light in each aerial image 173a, 173b. Specifically, a recipe can specify that, of the N pulses, a certain number of the pulses have a first primary wavelength that forms aerial image 173a, and a certain number of the pulses have a second primary wavelength that forms aerial image 173b.

[0058]

[0071] Also, the slit 176 and / or mask 174 can be moved in the scan direction in the xy plane so that only a portion of the wafer 170 is exposed at a given time or during a particular exposure scan (or exposure pass). The size of the area exposed by the light beam 160 on the wafer 170 is determined by the non-scanning distance between the blades and by the scan-direction length (distance) of the scan. In some implementations, the value of N is a few tens, e.g., 10-100 pulses. In other implementations, the value of N is greater than 100 pulses, e.g., 100-500 pulses. The exposure field 479 of the wafer 170 is the physical area of ​​the wafer 170 that is exposed in one scan of an exposure slit or window in the lithography exposure tool 169.

[0059]

[0072] The wafer stage 171, mask 174, and objective arrangement 432 are mounted on associated motion systems to form a scan arrangement, in which one or more of the mask 174, objective arrangement 432, and wafer 170 (via stage 171) can move relative to one another in the xy plane. However, apart from incidental relative motion between the wafer stage 171, mask 174, and objective arrangement 432, these elements do not move relative to one another along the z-axis during or during an exposure pass.

[0060]

[0073] Referring to Figure 5, a flow chart of a process 500 is shown. The process 500 is an example of a process for forming a three-dimensional semiconductor component or a portion of such a component. The process 500 can be performed using the photolithography systems 100 or 200. The process 500 will be discussed with respect to the system 200 shown in Figure 2A. The process 500 will also be discussed with respect to Figures 6A-10B.

[0061]

[0074] Light beam 260 is directed (510) at mask 174. Light beam 260 is a pulsed light beam that includes multiple pulses, each pulse separated in time from one another as shown in FIG. 3C. FIGs. 6A and 6B show example optical spectra of a single pulse that is part of light beam 260. Other pulses in light beam 260 can have different optical spectra.

[0062]

[0075] 6A, an optical spectrum 601A of an optical pulse 600A is shown. The pulse 600A has a non-zero intensity within a wavelength band, which may also be referred to as the bandwidth of the pulse 600A.

[0063]

[0076] The information shown in FIG. 6A is the instantaneous optical spectrum 601A (or emission spectrum) of the pulse 600A. The optical spectrum 601A contains information about how the optical energy or power of the pulse of the light beam 260 is distributed among different wavelengths (or frequencies). The optical spectrum 601A is depicted diagrammatically, plotting the spectral intensity (not necessarily with absolute calibration) as a function of wavelength or optical frequency. The optical spectrum 601A may be referred to as the spectral shape or intensity spectrum of the pulse of the light beam 260. The pulse 600A has a primary wavelength 602A, which in the example of FIG. 6A is the peak intensity. Although the discussion of the pulse of the light beam 260 and the aerial image formed by the pulse of the light beam 260 refers to the primary wavelength of the pulse, the pulse includes wavelengths other than the primary wavelength and has a finite bandwidth that can be characterized by a metric. For example, the total width of the spectrum 601A (called FWXM) as a fraction (X) of the maximum peak intensity of the spectral shape can be used to characterize the optical beam bandwidth. As another example, the width of the spectrum (referred to as EY), which comprises a fraction of the integrated spectral intensity (Y), can be used to characterize the optical beam bandwidth.

[0064]

[0077] Pulse 600A is shown as an example of a pulse that may be present in light beam 260. When pulse 600A is used to expose a portion of wafer 120, the pulse of light forms an aerial image. The position of the aerial image in the z-direction (FIGS. 1C and 4) is determined by the value of primary wavelength 602A. The various pulses of light beam 260 may have different primary wavelengths. For example, to generate two aerial images during a single exposure pass, some pulses of light beam 260 have one primary wavelength (first primary wavelength) and other pulses of light beam 260 have another primary wavelength (second primary wavelength). The first and second primary wavelengths are different wavelengths. The wavelength difference between the first and second primary wavelengths may be referred to as the spectral separation. The spectral separation may be, for example, 200 femtometers (fm) to 5 picometers (pm). Although the wavelengths of the various pulses of light beam 260 may be different, the shape of the optical spectrum of the pulses may be the same.

[0065]

[0078] The light source 205 can dither the primary wavelength, i.e., switch between the first and second primary wavelengths, for each pulse, such that every pulse has a different primary wavelength than the pulses immediately preceding or following it in time. In these implementations, this distribution of the first and second primary wavelengths produces two aerial images with the same intensity at different positions in the z-direction, assuming that all pulses in the light beam 260 have the same intensity.

[0066]

[0079] In some implementations, a portion of the pulses (e.g., 33%) have the first primary wavelength and the remaining portion (67% in this example) have the second primary wavelength. In these implementations, assuming all the pulses in light beam 260 have the same intensity, two aerial images are formed having different intensities. The aerial image formed by the pulses having the first primary wavelength has approximately half the intensity of the aerial image formed by the pulses having the second primary wavelength. In this manner, the dose delivered to a particular location along the z-axis of wafer 170 can be controlled by controlling the fraction of the N pulses having each of the first and second primary wavelengths.

[0067]

[0080] The fraction of the pulses that will have a particular primary wavelength for an exposure pass can be defined in a recipe file 259 stored in electronic storage 252. The recipe 259 defines the proportions of the various primary wavelengths for an exposure pass. The recipe 259 can also define proportions for other exposure passes, so that different proportions can be used for other exposure passes and the aerial image can be adjusted or controlled on a field by field basis.

[0068]

[0081] Referring to FIG. 6B, an optical spectrum 601B of pulse 600B is shown. Pulse 600B is another example of a pulse of light beam 260. Optical spectrum 601B of pulse 600B has a different shape than optical spectrum 601A. Specifically, optical spectrum 601B has two peaks corresponding to two primary wavelengths 602B_1 and 602B_2 of pulse 600B. Pulse 600B is part of light beam 260. When pulse 600B is used to expose a portion of wafer 120, the light of the pulse forms two aerial images at different positions along the z-axis on the wafer. The positions of the aerial images are determined by the wavelengths of the primary wavelengths 602B_1 and 602B_2.

[0069]

[0082] The pulses shown in FIGS. 6A and 6B can be formed by any hardware capable of forming such pulses. For example, a pulse train of pulses such as pulse 600A can be formed using a line narrowing module similar to line narrowing module 216C of FIG. 2C. The wavelength of light diffracted by grating 291 depends on the angle of light incident on the grating. A mechanism for varying the angle of incidence of light interacting with grating 291 can be used with such a line narrowing module to create a pulse train including N pulses for an exposure pass, where at least one of the N pulses has a different primary wavelength than another of the N pulses. For example, one of prisms 292, 293, 294, 295 can be rotated to vary the angle of light incident on grating 291 from pulse to pulse. In some implementations, the line narrowing module includes a mirror in the path of beam 260 that can be moved to vary the angle of light incident on grating 291. Examples of such implementations are discussed, for example, in US Pat. No. 6,192,064, issued Feb. 20, 2001, and entitled NARROW BAND LASER WITH FINE WAVELENGTH CONTROL.

[0070]

[0083] Pulses such as pulse 600B (FIG. 6B) can also be formed using a line narrowing module similar to line narrowing module 216C of FIG. 2C. For example, a stimulated optical element such as an acousto-optic modulator can be placed in line narrowing module 216C on the path of beam 260. The acousto-optic modulator deflects incident light at an angle that depends on the frequency of the acoustic wave used to excite the modulator. The acoustic modulator comprises a material, such as glass or quartz, that allows for the propagation of acoustic waves, and a transducer coupled to the material. The transducer vibrates in response to an excitation signal, and the vibrations generate acoustic waves in the material. The acoustic waves create moving expansion and compression surfaces that change the refractive index of the material. As a result, the acoustic waves act as a diffraction grating that diffracts the incident light and exits the material simultaneously at several different angles. Light from two or more orders can be made to reach grating 291, with each of the various diffracted orders having a different angle of incidence to grating 291. In this manner, a single pulse can be formed that includes two or more primary wavelengths. An example of a line narrowing module comprising an acousto-optic modulator is discussed, for example, in U.S. Pat. No. 7,154,928, issued Dec. 26, 2006, and entitled LASER OUTPUT BEAM WAVEFRONT SPLITTER FOR BANDWIDTH SPECTRUM CONTROL.

[0071]

[0084] During a single exposure pass, a set of light pulses is directed through the mask 174 toward the wafer 170 (520). As discussed above, N light pulses can be provided to the wafer 170 during an exposure pass. The N light pulses can be consecutive light pulses of the beam 260. The exposed portion of the wafer 170 is an average of the optical spectra of each of the N pulses during the exposure pass. Thus, if a portion of the N pulses have a first primary wavelength and the remainder of the N pulses have a second primary wavelength, the average optical spectrum at the wafer 170 is an optical spectrum that includes a peak at the first primary wavelength and a peak at the second primary wavelength. Similarly, if all or a portion of the individual pulses of the N pulses have more than one primary wavelength, the primary wavelengths can form peaks in the average optical spectrum. FIG. 7 illustrates an example of an average optical spectrum 701 at the wafer 170. The average optical spectrum 701 includes a first primary wavelength 702_1 and a second primary wavelength 702_2. 7, the first primary wavelength 702_1 and the second primary wavelength 702_2 are separated by a spectral separation 703 of approximately 500 fm, although other combinations are contemplated. The spectral separation 703 is such that the first primary wavelength 702_1 and the second primary wavelength 702_2 are different and the average optical spectrum 701 includes a spectral region 704 where there is little or no intensity between the wavelengths 702_1 and 702_2.

[0072]

[0085] Two or more aerial images, for example, a first aerial image based on a first primary wavelength and a second aerial image based on a second primary wavelength, are formed on the wafer 170 based on the average optical spectrum (530). Continuing with the example of the average optical spectrum 701 and still referring to FIG. 8A, two aerial images 873a and 873b are formed in a single exposure pass based on N pulses. The N pulses include pulses having a first primary wavelength 702_1 and pulses having a second primary wavelength 702_2. The pulses having the first primary wavelength 702_1 form the first aerial image 873a, and the pulses having the second primary wavelength 702_2 form the second aerial image 873b. The aerial image 873a is formed in a first plane 878a, and the aerial image 873b is formed in a second plane 878b. The planes 878a and 878b are perpendicular to the propagation direction of the light beam 260 on the wafer 170. Planes 878a and 878b are separated by a separation distance 879 along the z direction.

[0073]

[0086] The separation distance 879 is greater than the depth of focus of the lithography apparatus 169 for an average optical spectrum having a single primary wavelength. The depth of focus can be defined as the range of focus along the z-direction for which, for a dose value (amount of optical energy delivered to the wafer), that dose provides a feature size that is within the feature size tolerance range for the process being applied to the wafer 170. The process 500 can increase the depth of focus of the lithography exposure apparatus 169 by providing two or more different aerial images to the wafer 170 during a single exposure pass. This is because each of the multiple aerial images can expose the wafer at a different position in the z-direction with features that are within the feature size tolerance range. In other words, the process 500 can provide a wider range of depth of focus to the lithography exposure apparatus 169 during a single exposure pass. As discussed above, an operator of the lithography exposure apparatus 169 can control various parameters of the exposure process using the recipe file 259. In some implementations, an operator of the lithography exposure tool 169 can obtain information from a simulation program, such as Tachyon Source-Mask Optimization (SMO), available from Brion, an ASML company, and use this information to program or specify parameters in the recipe file 259. For example, the operator of the lithography exposure tool 169 may know that an upcoming lot will not require as much depth of focus as a previously exposed lot. In this example, the operator specifies the depth of focus and dose variation to a simulation program, which returns a value for the spectral separation 703 to obtain the desired parameters. The operator can then prescribe the value of the spectral separation 703 for the upcoming lot by programming the recipe file 259 using the I / O interface 253. In some implementations, the operator can use the simulation to determine whether a particular exposure pass requires a larger depth of focus (such as may be possible by exposing the wafer 170 with multiple aerial images at different planes).If a greater depth of focus is not required to form a particular portion of a semiconductor component, the recipe file 259 can be configured, for example, so that the exposure pass used to form that particular portion of the semiconductor component has an average optical spectrum that includes a single primary wavelength.

[0074]

[0087] The operator and / or simulator can also obtain information about the formed three-dimensional component as measured by metrology system 172 or by another sensor. For example, metrology system 172 can provide data regarding sidewall angles of the formed 3D semiconductor component, which can be used to program parameters in recipe file 259 for subsequent exposure passes.

[0075]

[0088] Figure 8B shows an aerial image 873a in the xy plane (looking into the page of Figure 8A) at plane 878a. Aerial images 873a and 873b are generally two-dimensional intensity patterns formed in the xy plane. The nature of this intensity pattern depends on the properties of mask 174. The first and second planes 878a, 878b are portions of wafer 170. As shown in Figure 8B, first plane 878a may be only a small portion of the entire wafer 170.

[0076]

[0089] The value of separation distance 879 depends on the spectral separation 703 and the characteristics of optical system 275. For example, the value of separation distance 879 can depend on the focal length, aberrations, and other characteristics of the lenses and other optical elements in optical system 275. For a scanner lens having chromatic aberration C, separation distance 879 can be determined from Equation 1: ΔD=C*Δλ Equation (1) where ΔD is the separation distance 879 in nanometers (nm), C is the chromatic aberration (defined as the distance the focal plane moves in the propagation direction due to a change in wavelength), and Δλ is the spectral separation 873 in picometers. The separation distance 875 may be, for example, 5000 nm (5 μm), and the spectral separation 873 may be about 200-300 fm.

[0077]

[0090] Also, due to variations in the manufacturing and installation process and / or modifications by the end user, a different primary wavelength may be required to achieve the desired separation distance 879 for a particular instance of a type of lithography exposure apparatus 169. As discussed above, a recipe or process control program 259 may be stored in electronic storage 252 of the control system 250. The recipe 259 may be modified or programmed to be customized for a particular exposure apparatus or type of exposure apparatus. The recipe 259 may be programmed when the lithography system 200 is manufactured and / or the recipe 259 may be programmed by an end user or other operator familiar with the operation of the system 200, for example, via the I / O interface 253.

[0078]

[0091] The recipe 259 may also specify different separation distances 879 for different exposure passes used to expose different areas of the wafer 170. Additionally or alternatively, the recipe 259 may specify the separation distances 879 per lot or per layer or per wafer. A lot or layer is a group of wafers processed by the same exposure tool under the same nominal conditions. The recipe 259 may also specify other parameters related to the aerial images 873a, 873b, such as the dose provided by each image. For example, the recipe 259 may specify the ratio of the number of pulses having the first primary wavelength 702_1 to the number of pulses having the second primary wavelength 702_2 out of N pulses. These other parameters may also be specified per field, per lot (or per layer) and / or per wafer.

[0079]

[0092] Also, recipe 259 can specify that some layers are not exposed with the first primary wavelength 702_1 and the second primary wavelength 702_2, but are instead exposed with pulses having an optical spectrum that includes a single primary wavelength. Such an optical spectrum can be used, for example, when planar semiconductor components are to be formed rather than three-dimensional semiconductor components. I / O interface 253 allows an end user and / or manufacturer to program or create recipes that specify the number of primary wavelengths, including scenarios where a single primary wavelength is used, for example, for a particular layer or lot.

[0080]

[0093] Also, while the above examples discuss an average optical spectrum 701 having two primary wavelengths, in other examples, the average optical spectrum 701 can have more than two primary wavelengths (e.g., three, four, or five primary wavelengths), each separated from the nearest other primary wavelength by a spectral separation and region, such as region 704. I / O interface 253 allows the end user and / or manufacturer to program or create recipes that define these parameters.

[0081]

[0094] A three-dimensional (3D) semiconductor component is formed (540). FIG. 9A illustrates a cross-sectional view of an exemplary 3D semiconductor component 995. FIG. 9B illustrates the wafer 170 and the component 995 in the xy plane at the first plane 878a. The 3D semiconductor component 995 may be a complete component or a portion of a larger component. The 3D semiconductor component 995 may be any type of semiconductor component having features that are not all formed at one z location in the wafer 170. For example, the 3D semiconductor component may be a device with a recess or opening that extends along the z-axis. For example, the 3D semiconductor component may be all or part of a 3D NAND flash memory component. A 3D NAND flash memory is a memory in which memory cells are stacked along the z-axis.

[0082]

[0095] In the example of Figure 9A, 3D semiconductor component 995 comprises a recess 996 formed in exterior surface 999. Recess 996 comprises a floor 997 and a sidewall 998 extending generally along the z-axis between exterior surface 999 and floor 997. Floor 997 is formed by exposing photoresist at plane 878b to light in second aerial image 873b (Figure 8A). Features on exterior surface 999 are formed using light in first aerial image 873a (Figure 8A).

[0083]

[0096] Using process 500 can also produce a sidewall angle 992 that is equal to or closer to 90° than is possible using other processes. Sidewall angle 992 is the angle between floor 997 and sidewall 998. If sidewall 998 extends in the xz plane and floor extends in the xy plane, sidewall angle 992 is 90° and can be considered vertical in this example. Vertical sidewall angles are desirable because, for example, such sidewalls enable better defined features of 3D semiconductor components. Process 500 achieves sidewall angle 992 that is equal to or closer to 90° because the locations of first aerial image 873a and second aerial image 873b (first plane 878a and second plane 878b, respectively) are separate images in different portions of wafer 170. Forming separate aerial images in a single exposure pass can improve the quality of each image, resulting in more vertically oriented and better defined features compared to features formed by a lower quality single aerial image.

[0084]

[0097] 10A and 10B are examples of simulated data associated with process 500. FIG. 10A shows three plots 1001, 1002, 1003 of aerial image intensity versus mask position along the y-axis (FIG. 9A). Each plot 1001, 1002, 1003 represents the intensity versus mask position of one aerial image. In FIG. 10A, plot 1001 represents a simulation of the average optical spectrum forming two aerial images during a single exposure pass as described above for FIG. 5. Plot 1002 represents a simulation of tilting the wafer stage according to ASML's EFESE technique, a procedure that increases the depth of focus to facilitate printing three-dimensional features (such as vias and holes) on a wafer. In the EFESE technique, the wafer stage is tilted at an angle to scan the aerial image through the focus while exposing the wafer. The EFESE technique generally results in a larger depth of focus. In FIG. 10A, only plot 1002 represents data simulated using the EFESE technique. The remaining data shown in Figure 10A did not employ the EFESE technique. Plot 1003 represents data from a dose-based best focus simulation.

[0085]

[0098] Aerial image intensity as a function of mask position, shown in Figure 10A, indicates that forming two or more aerial images in a single exposure pass can produce similar contrast as tilting the wafer stage. Greater contrast indicates that 3D features at different positions along the z-axis (Figure 8A) are more likely to be properly formed.

[0086]

[0099] FIG. 10B shows three plots 1004, 1005, 1006 of critical dimension as a function of focus position for three different aerial images, each averaged during an exposure pass. Plot 1004 in FIG. 10B represents data from a simulation in which a single aerial image was formed without applying the EFESE technique. Plot 1005 represents data from a simulation in which the EFESE technique was applied. As shown, the EFESE technique increases the depth of focus compared to the simulation without the application of EFESE, since the critical dimension values ​​do not change further away from zero focus. Plot 1005 represents data from a simulation in which two aerial images were generated in a single exposure pass, and the EFESE technique was not applied. The depth of focus of the simulation without the EFESE technique using multiple aerial images is comparable or better than the EFESE technique. Thus, a larger depth of focus can be achieved in a single exposure pass using process 500 without resorting to techniques such as EFESE.

[0087]

[0100] The embodiments can be further described using the following clauses. 1. A method for forming a three-dimensional semiconductor component using a photolithography system, the method comprising: directing a pulsed light beam, the pulsed light beam including a plurality of light pulses, along a propagation direction toward a mask; directing a set of light pulses of a light beam through the mask and onto the wafer during a single exposure pass; generating at least a first aerial image and a second aerial image on the wafer based on the light pulses in the set of pulses passing through the mask during a single exposure pass, the first aerial image being at a first plane on the wafer and the second aerial image being at a second plane on the wafer, the first plane and the second plane being separated from each other along a propagation direction by a separation distance; patterning a three-dimensional semiconductor component in the photoresist based on an interaction of the light of the first aerial image with a material of the first portion of the wafer and an interaction of the light of the second aerial image with a material of the second portion of the wafer; The method of claim 1, wherein at least one of the pulses in the set of pulses has a first primary wavelength and at least one other pulse in the set of pulses has a second primary wavelength that is different from the first primary wavelength, such that the spectra of the first and second pulse sets are spectrally distinct, and the separation distance is based on the difference between the first primary wavelength and the second primary wavelength. 2. The method of claim 1, wherein at least one of the pulses in the set of pulses that passes through the mask during a single exposure pass includes two or more primary wavelengths of light. 3. The method of claim 2, wherein each primary wavelength is separated from the nearest other primary wavelength by a spectral separation of 200 femtometers (fm) to 500 picometers (pm). 4. The method of claim 1, wherein the separation distance between the first aerial image and the second aerial image is changed during a single exposure pass. 5. The method of clause 1, wherein the single exposure pass is a first exposure pass, and the method further includes directing a second set of light pulses of the light beam through the mask to the wafer during a second exposure pass and after the first exposure pass is completed, and wherein a separation distance between the first aerial image and the second aerial image is different during the first exposure pass and the second exposure pass. 6. The method of claim 1, wherein a separation distance between the first aerial image and the second aerial image is set prior to the single exposure pass, and the separation distance does not change during the single exposure pass. 7. The method of clause 6, wherein a separation distance between the first aerial image and the second aerial image is set to accommodate one or more features of a photolithography system. 8. The set of pulses includes a first group of light pulses and a second group of light pulses, each pulse in the first group of light pulses having a first primary wavelength and each pulse in the second group of light pulses having a second primary wavelength, and the method further comprises: controlling an amount of light of the first aerial image by controlling a characteristic of the first group of pulses; and 2. The method of claim 1, comprising controlling the amount of light of the second aerial image by controlling a characteristic of the second group of pulses. 9. The method of claim 8, wherein the first group of characteristics includes a number of pulses in the first group and the second group of characteristics includes a number of pulses in the second group. 10. The method of claim 9, wherein controlling the number of pulses in the first group includes determining a first number of pulses to include in the first group of pulses before the single exposure pass begins, and controlling the number of pulses in the second group of pulses includes determining a second number of pulses to include in the second group of pulses before the single exposure pass. 11. The method of claim 10, wherein determining the first number of pulses and the second number of pulses includes one or more of: (a) receiving input from an operator; and (b) accessing predefined settings associated with the photolithography system. 12. The method of claim 8, wherein the characteristics of the first group of pulses include an intensity of each pulse in the first group, and the characteristics of the second group of pulses include an intensity of each pulse in the second group. 13. The method of claim 1, wherein the first plane on the wafer and the second plane on the wafer are planes that are substantially perpendicular to the direction of propagation. 14. The method of claim 9, wherein the first group of pulses and the second group of pulses include all pulses that pass through the mask in a single exposure pass. 15. A three-dimensional semiconductor first feature is formed in a first plane; A three-dimensional semiconductor second feature is formed in the second plane; 2. The method of claim 1, wherein the first and second features are separated from one another by sidewalls that extend substantially parallel to the direction of propagation. 16. The method of clause 1, wherein the three-dimensional semiconductor component includes a three-dimensional NAND flash memory component. 17. The method of claim 1, wherein the first plane corresponds to a first focal plane and the second plane corresponds to a second focal plane, and a separation distance between the first plane and the second plane is based on one or more wavelength differences of the light pulses passing through the mask or wavelength differences between individual pulses of the set of pulses. 18. Light source and a mask positioned to interact with the pulsed light beam from the light source; a lithography scanner apparatus comprising: a control system coupled to the light source, a control system configured to cause the light source to emit a pulsed light beam toward the lithography scanner apparatus during a single exposure pass, during which at least a first aerial image and a second aerial image are formed on a wafer supported by a wafer holder based on a set of light pulses passing through a mask along a propagation direction, the first aerial image being at a first plane on the wafer and the second aerial image being at a second plane on the wafer, the first plane and the second plane being spaced apart from each other along the propagation direction by a separation distance, and a three-dimensional semiconductor component being formed based on an interaction of the light of the first aerial image with a material of a first portion of the wafer and an interaction of the light of the second aerial image with a material of a second portion of the wafer; At least one of the pulses in the set of pulses has a first primary wavelength; at least one of the other pulses in the set of pulses has a second primary wavelength that differs from the first primary wavelength such that the spectra of the first and second sets of pulses are spectrally distinct; A photolithography system, wherein the separation distance is based on a difference between the first primary wavelength and the second primary wavelength. 19. A photolithography system as described in clause 18, wherein the control system comprises a computer-readable storage medium, one or more electronic processors coupled to the computer-readable storage medium, and an input / output interface, and wherein recipes associated with the photolithography system are stored in the computer-readable storage medium. 20. The photolithography system of clause 19, wherein a recipe defines the separation distance. 21. The photolithography system of clause 20, wherein a recipe defines the separation distance on a per-wafer or per-lot basis. 22. The photolithography system of claim 18, wherein the light source comprises a krypton fluoride (KrF) gain medium or an argon fluoride (ArF) gain medium.

[0088]

[0101] Other implementations are within the scope of the claims.

Claims

1. 1. A method for forming a three-dimensional semiconductor component using a photolithography system, comprising: directing a pulsed light beam, the pulsed light beam including a plurality of light pulses, along a propagation direction toward a mask; directing the set of light pulses of the light beam through the mask and onto a wafer during a single exposure pass; generating at least a first aerial image and a second aerial image on the wafer based on the light pulses in the set of pulses passing through the mask during the single exposure pass, the first aerial image being at a first plane on the wafer and the second aerial image being at a second plane on the wafer, the first plane and the second plane being separated from each other by a separation distance along the propagation direction; patterning the three-dimensional semiconductor component in photoresist based on an interaction of the light of the first aerial image with a material of a first portion of the wafer and an interaction of the light of the second aerial image with a material of a second portion of the wafer; at least one of the pulses in the set of pulses has a first primary wavelength and at least one other pulse in the set of pulses has a second primary wavelength different from the first primary wavelength, such that the spectra of the first and second sets of pulses are spectrally distinct; The method, wherein the separation distance is based on a difference between the first primary wavelength and the second primary wavelength.

2. The method of claim 1 , wherein at least one of the pulses in the set of pulses that passes through the mask during the single exposure pass comprises two or more primary wavelengths of light.

3. 3. The method of claim 2, wherein each primary wavelength is separated from the nearest other primary wavelength by a spectral separation of 200 femtometers (fm) to 500 picometers (pm).

4. The method of claim 1 , wherein the separation distance between the first aerial image and the second aerial image varies during the single exposure pass.

5. the single exposure pass is a first exposure pass; the method further includes directing a second set of light pulses of the light beam through the mask to the wafer during a second exposure pass and after the first exposure pass is completed; The method of claim 1 , wherein the separation distance between the first aerial image and the second aerial image is different during the first exposure pass and the second exposure pass.

6. the separation distance between the first aerial image and the second aerial image is set prior to the single exposure pass; The method of claim 1 , wherein the separation distance does not change during the single exposure pass.

7. The method of claim 6 , wherein the separation distance between the first aerial image and the second aerial image is set to accommodate one or more features of the photolithography system.

8. the set of pulses includes a first group of light pulses and a second group of light pulses; each pulse of the first group of light pulses having the first primary wavelength; each pulse of the second group of light pulses having the second primary wavelength; The method further comprises: controlling an amount of light of the first aerial image by controlling a characteristic of the first group of pulses; controlling an amount of light of the second aerial image by controlling a characteristic of the second group of pulses; The method of claim 1 , comprising:

9. the characteristics of the first group include a number of pulses of the first group; The method of claim 8 , wherein the characteristics of the second group include a number of pulses of the second group.

10. controlling the number of pulses in the first group includes determining a first number of pulses to include in the first group of pulses before the single exposure pass begins; 10. The method of claim 9, wherein controlling the number of pulses in the second group of pulses comprises determining a second number of pulses to include in the second group of pulses prior to the single exposure pass.

11. 11. The method of claim 10, wherein determining the first number of pulses and the second number of pulses comprises one or more of: (a) receiving input from an operator; and (b) accessing predefined settings associated with the photolithography system.

12. the characteristics of the first group of pulses include an intensity of each pulse in the first group; The method of claim 8 , wherein the characteristics of the second group of pulses include an intensity of each pulse in the second group.

13. The method of claim 1 , wherein the first plane on the wafer and the second plane on the wafer are planes that are substantially perpendicular to the direction of propagation.

14. 10. The method of claim 9, wherein the first group of pulses and the second group of pulses include all pulses that pass through the mask in the single exposure pass.

15. the three-dimensional semiconductor first feature is formed in the first plane; a second feature of the three-dimensional semiconductor is formed in the second plane; The method of claim 1 , wherein the first and second features are separated from one another by sidewalls that extend substantially parallel to the direction of propagation.

16. The method of claim 1 , wherein the three-dimensional semiconductor component comprises a three-dimensional NAND flash memory component.

17. the first plane corresponds to a first focal plane; the second plane corresponds to a second focal plane; 2. The method of claim 1, wherein the separation distance between the first plane and the second plane is based on one or more wavelength differences of light pulses passing through the mask or wavelength differences between individual pulses of the set of pulses.

18. A light source; a lithography scanner apparatus having a mask and a wafer holder arranged to interact with the pulsed light beam from the light source; a control system coupled to the light source; A photolithography system comprising: the control system is configured to cause the light source to emit the pulsed light beam towards the lithography scanner apparatus during a single exposure pass, during which at least a first aerial image and a second aerial image are formed on a wafer supported by the wafer holder based on a set of light pulses passing through the mask along a propagation direction, the first aerial image being at a first plane on the wafer and the second aerial image being at a second plane on the wafer, the first plane and the second plane being spaced apart from each other along the propagation direction by a separation distance, and a three-dimensional semiconductor component is formed based on an interaction of the light of the first aerial image with a material of a first portion of the wafer and an interaction of the light of the second aerial image with a material of a second portion of the wafer; At least one of the pulses in the set of pulses has a first primary wavelength; at least one of the other pulses in the set of pulses has a second primary wavelength different from the first primary wavelength such that the spectra of the first and second sets of pulses are spectrally distinct; The photolithography system, wherein the separation distance is based on a difference between the first primary wavelength and the second primary wavelength.

19. the control system comprising a computer-readable storage medium, one or more electronic processors coupled to the computer-readable storage medium, and an input / output interface; The photolithography system of claim 18 , wherein a recipe associated with the photolithography system is stored in the computer readable storage medium.

20. The photolithography system of claim 19 , wherein the recipe defines the separation distance.

21. 21. The photolithography system of claim 20, wherein the recipe defines the separation distance on a wafer-by-wafer or lot-by-lot basis.

22. 20. The photolithography system of claim 18, wherein the light source comprises a krypton fluoride (KrF) gain medium or an argon fluoride (ArF) gain medium.

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