Film structure for electric field induced photoresist patterning process.

Abstract

A method and apparatus are provided for minimizing line edge / width roughness of photolithographically formed lines. [Solution] A method for treating a substrate includes adding a photoresist layer containing a photoacid generator onto a multilayer disposed on the substrate, the multilayer including an underlayer formed from an organic material, an inorganic material, or a mixture of organic and inorganic materials, and the method further includes exposing a first portion of the photoresist layer that is not protected by a photomask to radiation in a lithographic exposure step, and applying an electric or magnetic field to change the migration of photoacid generated from the photoacid generator in a substantially vertical direction.

Description

[Technical Field]

[0001] FIELD OF THE DISCLOSURE

[0001] The present disclosure relates generally to methods and apparatus for processing substrates, and more particularly to methods and apparatus for improving photoresist profile control. [Background technology]

[0002]

[0002] Integrated circuits have evolved into complex devices that can contain millions of components (e.g., transistors, capacitors, and resistors) on a single chip. Photolithography can be used to form the components on the chip. Generally, the photolithography process includes several basic steps. First, a photoresist layer is formed on a substrate. This photoresist layer can be formed, for example, by spin coating. The photoresist layer can include a resist resin and a photoacid generator. The photoacid generator, when exposed to electromagnetic radiation in a subsequent exposure step, changes the solubility of the photoresist in a development process. The electromagnetic radiation can have any suitable wavelength, such as a wavelength in the extreme ultraviolet range. The electromagnetic radiation can be from any suitable source, such as a 193 nm ArF laser, an electron beam, an ion beam, or other source. Excess solvent can then be removed in a pre-exposure bake step.

[0003]

[0003] In the exposure step, a photomask or reticle may be used to selectively expose specific regions of a photoresist layer disposed on a substrate to electromagnetic radiation. Other exposure methods may be maskless exposure methods. Upon exposure, the photoacid generator decomposes, which generates acid, which may create a latent acid image in the resist resin. After exposure, the substrate may be heated in a post-exposure bake step. During the post-exposure bake step, the acid generated by the photoacid generator reacts with the resist resin in the photoresist layer, changing the solubility of the resist of the photoresist layer during the subsequent development process.

[0004] After the post-exposure bake, the substrate (particularly the photoresist layer) can be developed and rinsed. Then, after development and rinsing, a patterned photoresist layer is formed on the substrate, as shown in FIG. 1. FIG. 1 illustrates an exemplary top cross-sectional view of a substrate 100 having a patterned photoresist layer 104 disposed on a target material 102 to be etched. Openings 106 are defined in the patterned photoresist layer 104, and after development and rinsing steps, the underlying target material 102 is exposed and etched, transferring features onto the target material 102. However, imprecise control or low resolution of the lithographic exposure process can cause inaccurate critical dimensions in the photoresist layer 104, resulting in unacceptable line width roughness (LWR) 108. Furthermore, during the exposure process, the acid generated from the photoacid generator (shown in FIG. 1) may randomly diffuse into any areas, including areas protected under the mask, where it is not intended to diffuse, thus creating an undesirable wigging or roughness profile 150 at the edge or interface of the patterned photoresist layer 104 interfaced with the opening 106. The large linewidth roughness (LWR) 108 and undesirable wiggling profile 150 of the photoresist layer 104 can result in inaccurate feature transfer to the target material 102 and thus ultimately lead to device failure and yield loss.

[0005] Therefore, there is a need for a method and apparatus that controls line width roughness (LWR) and improves resolution as well as dose sensitivity to obtain a patterned photoresist layer with desired critical dimensions. Summary of the Invention

[0006]

[0006] Embodiments of the present disclosure include a method for forming a film structure for efficiently controlling the distribution and diffusion of acid from a photoacid generator in a photoresist layer during an exposure step or a pre-exposure or post-exposure bake step. In one example, a device structure includes a film structure disposed on a substrate and a plurality of openings formed in the film structure, wherein the openings formed across the substrate have a critical dimension uniformity of about 1 nm to 2 nm.

[0007]

[0007] In another embodiment, a method for treating a substrate includes adding a photoresist layer containing a photoacid generator onto a multilayer disposed on the substrate, the multilayer including an underlayer formed from an organic material, an inorganic material, or a mixture of organic and inorganic materials, the method further including exposing a first portion of the photoresist layer not protected by a photomask to radiation in a lithographic exposure step, and applying an electric or magnetic field to change the migration of photoacid generated from the photoacid generator in a substantially vertical direction.

[0008]

[0008] In yet another embodiment, a method for processing a substrate includes adding a photoresist layer over an underlayer disposed on the substrate, exposing a first portion of the photoresist layer that is not protected by a photomask to radiation in a lithographic exposure process, performing a baking process on the photoresist layer and the underlayer, and applying an electric or magnetic field while performing the baking process.

[0009]

[0009] In order to enable the above-mentioned features of the present disclosure to be understood in detail, the present disclosure briefly summarized above will now be more particularly described with reference to embodiments, some of which are illustrated in the accompanying drawings. It should be noted, however, that the accompanying drawings show only typical embodiments of the present disclosure, and therefore should not be considered as limiting the scope of the present disclosure, since the present disclosure may admit of other equally effective embodiments. [Brief explanation of the drawings]

[0010] [Figure 1]

[0010] FIG. 1 depicts a top view of an exemplary structure of a patterned photoresist layer disposed on a substrate in the prior art. [Figure 2]

[0011] 1 is a schematic cross-sectional view of an apparatus for processing a substrate according to one embodiment; [Figure 3]

[0012] FIG. 3 is a top view of one embodiment of an electrode assembly disposed within the device of FIG. 2. [Figure 4]

[0013] 1 depicts acid distribution control of a photoresist layer disposed on a film structure during an exposure process. [Figure 5]

[0014] 1 illustrates acid distribution control of a photoresist layer on a film structure with a desired profile during a post-exposure bake step. [Figure 6]

[0015] FIG. 1 is a flow diagram of one method for controlling acid distribution in a photoresist layer during an exposure process. DETAILED DESCRIPTION OF THE INVENTION

[0011]

[0016] For ease of understanding, where possible, the same reference numerals have been used to designate identical elements that are common to multiple figures. Additionally, elements of one embodiment may be advantageously adapted for use in other embodiments described herein.

[0012]

[0017] A method for improving profile control of a photoresist layer formed by photolithography is provided. The diffusion of acid generated by a photoacid generator during a post-exposure bake procedure, which contributes to line edge / width roughness, can be mitigated by utilizing a film structure disposed below the photoresist layer, as disclosed herein. The application of an electric field, as well as an underlayer disposed within the film structure below the photoresist layer, controls the diffusion and distribution of the acid generated by the photoacid generator within the photoresist layer, thus preventing line edge / width roughness resulting from random diffusion. A method for forming a film structure disposed below the photoresist layer that is utilized to control the distribution and diffusion of the acid is disclosed herein.

[0013]

[0018] Figure 2 is a schematic cross-sectional view of an apparatus for processing a substrate according to one embodiment. As shown in the embodiment of Figure 2, the apparatus may take the form of a reduced pressure processing chamber 200. In other embodiments, the processing chamber 200 may not be connected to a vacuum source.

[0014]

[0019] Processing chamber 200 may be an independent, stand-alone processing chamber. Alternatively, processing chamber 200 may be part of a processing system, such as an in-line processing system, a cluster processing system, or a track processing system, as desired. Processing chamber 200 is described in more detail below and may be used for pre-exposure bake, post-exposure bake, and / or other processing steps.

[0015]

[0020] The processing chamber 200 includes chamber walls 202, an electrode assembly 216, and a substrate support assembly 238. The chamber walls 202 include sidewalls 206, a lid assembly 210, and a bottom 208. The chamber walls 202 partially enclose a processing space 212. The processing space 212 is accessed through a substrate transfer port (not shown) configured to facilitate movement of a substrate 240 into and out of the processing chamber 200. In embodiments where the processing chamber 200 is part of a processing system, the substrate transfer port may enable transfer of the substrate 240 into and out of an adjacent transfer chamber.

[0016]

[0021] A pumping port 214 may optionally be disposed through one of the lid assembly 210, sidewalls 206, or bottom 208 of the processing chamber 200 to connect the processing space 212 to an exhaust port. The exhaust port connects the pumping port 214 to various vacuum pumping components, such as a vacuum pump. The pumping components may reduce the pressure in the processing space 212 and evacuate any gases and / or process by-products out of the processing chamber 200. The processing chamber 200 may be connected to one or more sources 204 for supplying one or more source compounds into the processing space 212.

[0017]

[0022] The substrate support assembly 238 is centrally disposed within the processing chamber 200. The substrate support assembly 238 supports the substrate 240 during processing. The substrate support assembly 238 may include a body 224 that encapsulates at least one embedded heater 232. In some embodiments, the substrate support assembly 238 may be an electrostatic chuck. The heater 232, such as a resistive element, is disposed within the substrate support assembly 238. The heater 232 controllably heats the substrate support assembly 238 and the substrate 240 disposed thereon to a predetermined temperature. The heater 232 is configured to rapidly and consistently increase the temperature of the substrate 240 and accurately control the temperature of the substrate 240. In some embodiments, the heater 232 is connected to and controlled by a power supply 274. The power supply 274 may alternatively or additionally apply power to the substrate support assembly 238. The power supply 274 may be configured similarly to the power supply 270 described below. Furthermore, it should be noted that the heater 232 may be positioned from other locations in the processing chamber 200, such as from the chamber walls, chamber liner, edge rings circumscribing the substrate or chamber ceiling, etc., as needed to provide thermal energy to a substrate 240 disposed on the substrate support assembly 238.

[0018]

[0023] In some embodiments, the substrate support assembly 238 may be configured to rotate. In some embodiments, the substrate support assembly 238 is configured to rotate about the z-axis. The substrate support assembly 238 may be configured to rotate continuously or constantly, or the substrate support assembly 238 may be configured to rotate in a stepped or indexing manner. For example, the substrate support assembly 238 may rotate a predetermined amount, such as 90 degrees, 180 degrees, or 270 degrees, and then the rotation may stop for a predetermined amount of time.

[0019]

[0024] Generally, the substrate support assembly 238 has a first surface 234 and a second surface 226. The first surface 234 is opposite the second surface 226. The first surface 234 is configured to support a substrate 240. A stem 242 is coupled to the second surface 226. The substrate 240 may be any type of substrate, such as a dielectric substrate, a glass substrate, a semiconductor substrate, or a conductive substrate. The substrate 240 may have a material layer 245 disposed thereon. The material layer 245 may be any desired layer. In other embodiments, the substrate 240 may have two or more material layers 245. The substrate 240 also has a photoresist layer 250 disposed on the material layer 245. The substrate 240 has already been exposed to electromagnetic radiation during an exposure step of a photolithography process. The photoresist layer 250 has latent image lines 255 formed therein from the exposure step. The latent image lines 255 can be substantially parallel. In other embodiments, the latent image lines 255 may not be substantially parallel. Also as shown, the first surface 234 of the substrate support assembly 238 is separated from the electrode assembly 216 by a distance d in the z-direction. The stem 242 is coupled to a lift system (not shown) for moving the substrate support assembly 238 between an elevated processing position (as shown) and a lowered substrate transfer position. The lift system can accurately and precisely control the position of the substrate 240 in the z-direction. In some embodiments, the lift system can also be configured to move the substrate 240 in the x-direction, the y-direction, or both the x- and y-directions. The stem 242 additionally provides a conduit for electrical and thermocouple leads between the substrate support assembly 238 and other components of the processing chamber 200. A bellows 246 is coupled to the substrate support assembly 238 to provide a vacuum seal between the processing space 212 and the atmosphere outside the processing chamber 200 and to facilitate movement of the substrate support assembly 238 in the z-direction.

[0020]

[0025] Optionally, the lid assembly 210 includes an inlet 280 through which gas supplied by the source 204 can enter the processing chamber 200. Optionally, the source 204 can controllably pressurize the processing space 212 with gases such as nitrogen, argon, helium, other gases, or combinations thereof. The gases from the source 204 can create a controlled environment within the processing chamber 200. Optionally, an actuator 290 can be coupled between the lid assembly 210 and the electrode assembly 216. The actuator 290 is configured to move the electrode assembly 216 in one or more of the x, y, and z directions. The x and y directions are referred to herein as lateral directions or lateral dimensions. The actuator 290 allows the electrode assembly 216 to scan across the surface of the substrate 240. The actuator 290 also allows the distance d to be adjusted. In some embodiments, the electrode assembly 216 is coupled to the lid assembly 210 by a fixed stem (not shown). In other embodiments, the electrode assembly 216 may be coupled to the inside of the bottom 208 of the processing chamber 200, to the second surface 226 of the substrate support assembly 238, or to the stem 242. In yet other embodiments, the electrode assembly 216 may be embedded between the first surface 234 and the second surface 226 of the substrate support assembly 238.

[0021]

[0026] The electrode assembly 216 includes at least a first electrode 258 and a second electrode 260. As shown, the first electrode 258 is connected to a power supply 270, and the second electrode 260 is connected to an optional power supply 275. In other embodiments, one of the first electrode 258 and the second electrode 260 may be connected to a power supply and the other electrode may be connected to ground. In some embodiments, the first electrode 258 and the second electrode 260 are connected to ground, and the power supply 274, which provides power to the substrate support, is a bipolar power supply that switches between a positive and a negative bias. In some embodiments, the power supply 270 or the power supply 275 may be connected to both the first electrode 258 and the second electrode 260. In other embodiments, the power supply 270 or the power supply 275 may be connected to the first electrode 258, the second electrode 260, and the substrate support assembly 238. In such an embodiment, the pulse delays to each of the first electrode 258, the second electrode 260, and the substrate support assembly 238 may be different. The electrode assembly 216 may be configured to generate an electric field parallel to an x-y plane defined by the first surface of the substrate support assembly 238. For example, the electrode assembly 216 may be configured to generate an electric field in one of the y direction, the x direction, or other directions within the x-y plane.

[0022]

[0027] Power supply 270 and power supply 275 are configured to supply, for example, about 500 V to about 100 kV to electrode assembly 216 to generate an electric field having a strength between about 0.1 MV / m and about 100 MV / m. In some embodiments, power supply 274 may also be configured to supply power to electrode assembly 216. In some embodiments, any or all of power supply 270, power supply 274, or power supply 275 are pulsed direct current (DC) power sources. The pulsed DC wave may be from a half-wave rectifier or a full-wave rectifier. The DC power may have a frequency between about 10 Hz and 1 MHz. The duty cycle of the pulsed DC power may be between about 5% and about 95%, such as between about 20% and about 60%. In some embodiments, the duty cycle of the pulsed DC power may be between about 20% and about 40%. In other embodiments, the duty cycle of the pulsed DC power may be about 60%. The rise and fall times of the pulsed DC power can be between about 1 ns and about 1000 ns, such as between about 10 ns and about 500 ns. In other embodiments, the rise and fall times of the pulsed DC power can be between about 10 ns and about 100 ns. In some embodiments, the rise and fall times of the pulsed DC power can be about 500 ns. In some embodiments, any or all of power source 270, power source 274, and power source 275 are AC power sources. In other embodiments, any or all of power source 270, power source 274, and power source 275 are DC power sources.

[0023]

[0028] In some embodiments, any or all of power supply 270, power supply 274, and power supply 275 may use a DC offset. The DC offset may be, for example, between about 0% and about 75% of the applied voltage (such as between about 5% and about 60% of the applied voltage). In some embodiments, while first electrode 258 and second electrode 260 are negatively pulsed, substrate support assembly 238 is also negatively pulsed. In these embodiments, first electrode 258 and second electrode 260 and substrate support assembly 238 are synchronized but offset in time. For example, first electrode 258 may be in a "1" state while the substrate support assembly is in a "0" state, and then substrate support assembly 238 may be in a "1" state while first electrode 258 is in a "0" state.

[0024]

[0029] The electrode assembly 216 spans approximately the width of the substrate support assembly 238. In other embodiments, the width of the electrode assembly 216 may be smaller than the width of the substrate support assembly 238. For example, the electrode assembly 216 may span between about 10% and about 80%, such as between about 20% and about 40%, of the width of the substrate support assembly 238. In embodiments in which the width of the electrode assembly 216 is smaller than the width of the substrate support assembly 238, the actuator 290 may scan the electrode assembly 216 across the surface of a substrate 240 disposed on the first surface 234 of the substrate support assembly 238. For example, the actuator 290 may scan the electrode assembly 216 so that the electrode assembly 216 scans the entire surface of the substrate 240. In other embodiments, the actuator 290 may scan only a portion of the substrate 240. Alternatively, the substrate support assembly 238 may scan underneath the electrode assembly 216.

[0025]

[0030] In some embodiments, one or more magnets 296 may be disposed within the processing chamber 200. In the embodiment shown in FIG. 2, the magnet 296 is coupled to the inner surface of the sidewall 206. In other embodiments, the magnet 296 may be disposed elsewhere within the processing chamber 200 or outside the processing chamber 200. The magnet 296 may be, for example, a permanent magnet or an electromagnet. Exemplary permanent magnets include ceramic magnets and rare earth magnets. In embodiments in which the magnet 296 includes an electromagnet, the magnet 296 may be connected to a power source (not shown). The magnet 296 is configured to generate a magnetic field in a direction perpendicular or parallel to the direction of the electric field lines generated by the electrode assembly 216 at the first surface 234 of the substrate support assembly 238. For example, the magnet 296 may be configured to generate a magnetic field in the x-direction when the electric field generated by the electrode assembly 216 is in the y-direction. The magnetic field drives the charged species 355 (shown in FIG. 2) and polarized species (not shown) generated by the photoacid generator in the photoresist layer 250 in a direction perpendicular to the magnetic field, such as a direction parallel to the latent image lines 255. By driving the charged species 355 and polarized species in a direction parallel to the latent image lines 255, line roughness can be reduced. The uniform directional movement of the charged species 355 and polarized species is indicated by double-headed arrow 370 in FIG. 3. In contrast, when no magnetic field is applied, the charged species 355 and polarized species can move randomly, as indicated by arrow 370′.

[0026]

[0031] Continuing to refer to FIG. 3 , the electrode assembly 216 includes at least a first electrode 258 and a second electrode 260. The first electrode 258 includes a first terminal 310, a first support structure 330, and one or more antennas 320. The second electrode 260 includes a second terminal 311, a second support structure 331, and one or more antennas 321. The first terminal 310, the first support structure 330, and the one or more antennas 320 of the first electrode 258 may form a single body. Alternatively, the first electrode 258 may include separate parts that may be coupled together. For example, the one or more antennas 320 may be detachable from the first support structure 330. Similarly, the second electrode 260 may be a single body or may be comprised of separate, detachable parts. The first electrode 258 and the second electrode 260 may be fabricated by any suitable technique. For example, the first electrode 258 and the second electrode 260 may be fabricated by machining, casting, or additive manufacturing.

[0027]

[0032] The first support structure 330 may be made of a conductive material such as a metal. For example, the first support structure 330 may be made of silicon, polysilicon, silicon carbide, molybdenum, aluminum, copper, graphite, silver, platinum, gold, palladium, zinc, other materials, or mixtures thereof. The first support structure 330 may have any desired dimensions. For example, the length L of the first support structure 330 may be between about 25 mm and about 450 mm, e.g., between about 100 mm and about 300 mm. In some embodiments, the first support structure 330 has a length L that is approximately equal to the diameter of a standard semiconductor substrate. In other embodiments, the first support structure 330 has a length L that is greater than or less than the diameter of a standard semiconductor substrate. For example, in various exemplary embodiments, the length L of the first support structure 330 can be about 25 mm, about 51 mm, about 76 mm, about 100 mm, about 150 mm, about 200 mm, about 300 mm, or about 450 mm. The width W of the first support structure 330 can be between about 2 mm and about 25 mm. In other embodiments, the width W of the first support structure 330 is less than about 2 mm. In other embodiments, the width W of the first support structure 330 is greater than about 25 mm. The thickness of the first support structure 330 can be between about 1 mm and about 10 mm, such as between about 2 mm and about 8 mm, such as about 5 mm. In some embodiments, the first support structure 330 can be square, cylindrical, rectangular, oval, rod-shaped, or other shape. Embodiments with curved outer surfaces can avoid arcing.

[0028]

[0033] The first support structure 330 can be made from the same material as the second support structure 331. The size ranges suitable for the first support structure 330 are also suitable for the second support structure 331. In some embodiments, the first support structure 330 and the second support structure 331 are made from the same material. In other embodiments, the first support structure 330 and the second support structure 331 are made from different materials. The length L, width W, and thickness of the first support structure 330 and the second support structure 331 may be the same or different.

[0029]

[0034] The one or more antennas 320 of the first electrode 258 may also be made from a conductive material. The one or more antennas 320 may be made from the same material as the first support structure 330. The one or more antennas 320 of the first electrode 258 may have any desired dimensions. For example, the length L1 of the one or more antennas 320 may be between about 25 mm and about 450 mm, such as between about 100 mm and about 300 mm. In some embodiments, the first support structure 330 has a length L1 that is approximately equal to the diameter of a standard substrate. In other embodiments, the length L1 of the one or more antennas 320 may be between about 75% and 90% of the diameter of a standard substrate. The width W1 of the one or more antennas 320 may be between about 2 mm and about 25 mm. In other embodiments, the width W1 of the one or more antennas 320 is less than about 2 mm. In other embodiments, the width W1 of the one or more antennas 320 is greater than 25 mm. The thickness of the one or more antennas 320 can be between about 1 mm and about 10 mm, such as between about 2 mm and about 8 mm. The one or more antennas 320 can have a square, rectangular, oval, circular, cylindrical, or another shaped cross section. Embodiments with rounded outer surfaces can avoid arcing.

[0030]

[0035] Each of the antennas 320 may have the same dimensions. Alternatively, some of the one or more antennas 320 may have different dimensions than one or more of the other antennas 320. For example, some of the one or more antennas 320 may have a different length L1 than one or more of the other antennas 320. Each of the one or more antennas 320 may be made from the same material. In other embodiments, some of the antennas 320 may be made from a different material than the other antennas 320.

[0031]

[0036] Antenna 321 can be made from the same range of materials as antenna 320. The range of dimensions suitable for antenna 320 is also suitable for antenna 321. In some embodiments, antenna 320 and antenna 321 are made from the same material. In other embodiments, antenna 320 and antenna 321 are made from different materials. The length L1, width W1, and thickness of antenna 320 and antenna 321 may be the same or different.

[0032]

[0037] The antennas 320 may include between 1 and about 40 antennas 320. For example, the antennas 320 may include between about 4 and about 40 antennas 320, such as between about 10 and about 20 antennas 320. In other embodiments, the antennas 320 may include more than 40 antennas 320. In some embodiments, each of the antennas 320 may be substantially perpendicular to the first support structure 330. For example, in embodiments in which the first support structure 330 is linear, each antenna 320 may be substantially parallel to the first support structure 330. Each antenna 320 may be substantially parallel to each of the other antennas 320. Each of the antennas 321 may be similarly positioned relative to the support structure 331 and each of the other antennas 321.

[0033]

[0038] Each of the antennas 320 has a termination 323. Each of the antennas 321 has a termination 325. A distance C is defined between the first support structure 330 and the termination 325. A distance C' is defined between the second support structure 331 and the termination 323. Each of the distances C and C' may be between about 1 mm and about 10 mm. In other embodiments, the distances C and C' may be less than about 1 mm or greater than about 10 mm. In some embodiments, the distances C and C' are equal. In other embodiments, the distances C and C' are different.

[0034]

[0039] A distance A is defined between the facing surfaces of one of the antennas 321 and one of the adjacent antennas 321. A distance A' is defined between the facing surfaces of one of the antennas 320 and one of the adjacent antennas 320. The distances A and A' may be greater than approximately 6 mm. For example, the distances A and A' may be between approximately 6 mm and approximately 20 mm, such as between approximately 10 mm and approximately 15 mm. The distances A and A' between each adjacent antenna 321, 320 may be the same or different. For example, the distances A' between the first and second antennas, the second and third antennas, and the third and fourth antennas of the one or more antennas 320 may be different. In other embodiments, the distances A' may be the same.

[0035]

[0040] A distance B is defined between the facing surfaces of one of the antennas 320 and one of the adjacent antennas 321. The distance B may be, for example, greater than about 1 mm. For example, the distance B may be between about 2 mm and about 10 mm, such as between about 4 mm and about 6 mm. The defined distances B may be the same, or each distance B may be different, or some distances B may be the same and some distances B may be different. Adjusting the distance B makes it possible to easily control the electric field strength.

[0036]

[0041] The antennas 320, 321 may be oriented in an alternating arrangement above the photoresist layer 250. For example, the antennas 320 of the first electrode 258 and the antennas 321 of the second electrode 260 may be arranged such that at least one of the antennas 320 is disposed between two of the antennas 321. In addition, at least one antenna 321 may be disposed between two of the antennas 320. In some embodiments, all but one of the antennas 320 are disposed between two of the antennas 321. In these embodiments, all but one of the antennas 321 are disposed between two of the antennas 320. In some embodiments, the antennas 320 and 321 may each have only one antenna.

[0037]

[0042] In some embodiments, the first electrode 258 has a first terminal 310 and the second electrode 260 has a second terminal 311. The first terminal 310 can be a contact between the first electrode 358 and the power source 270, the power source 275, or ground. The second terminal 311 can be a contact between the second electrode 260 and the power source 270, the power source 275, or ground. The first terminal 310 and the second terminal 311 are shown as being at one end of the first electrode 258 and the second electrode 260, respectively. In other embodiments, the first terminal 310 and the second terminal 311 can be located at other positions on the first electrode 258 and the second electrode, respectively. The first terminal 310 and the second terminal 311 have different shapes and sizes than the first support structure 330 and the second support structure 331, respectively. In other embodiments, first terminal 310 and second terminal 311 may generally have the same shape and size as first support structure 330 and second support structure 331, respectively.

[0038]

[0043] In operation, a voltage may be supplied to the first terminal 310, the second terminal 311, and / or the substrate support assembly 238 from a power source, such as power source 270, power source 274, or power source 275. The supplied voltage generates an electric field between each of the one or more antennas 320 and each of the one or more antennas 321. The electric field is strongest between an antenna of the one or more antennas 320 and an adjacent antenna of the one or more antennas 321. The alternating and aligned spatial relationship of the antennas 320, 321 generates an electric field in a direction parallel to the plane defined by the first surface 234 of the substrate support assembly 238. The substrate 240 is positioned on the first surface 234 such that the latent image lines 255 are parallel to the electric field lines generated by the electrode assembly 216. Because the charged species 355 are electrically charged, the charged species 355 are affected by the electric field. The charged species 355 generated by the photoacid generator in the photoresist layer 250 are driven by the electric field in the direction of the electric field. By driving the charged species 355 in a direction parallel to the latent image lines 255, line edge roughness can be reduced. This uniform directional movement is illustrated by the double-headed arrow 370. In contrast, when no voltage is applied to the first terminal 310 or the second terminal 311, no electric field is generated to drive the charged species 355 in any particular direction. As a result, the charged species 355 may move randomly, as indicated by the arrow 370′. This can result in wariness or line roughness.

[0039]

[0044] FIG. 4 depicts a film structure 404 disposed on a substrate 400 during a lithography exposure process. A photoresist layer 407 is disposed on the film structure 404. The film structure 404 includes an underlayer 405 disposed on a hard mask layer 403 and on a target layer 402. The target layer 402 is then patterned to form desired device features in the target layer 402. In one example, the underlayer 405 may be an organic material, an inorganic material, or a mixture of organic and inorganic materials. In embodiments where the underlayer 405 is an organic material, the organic material may be a cross-linkable polymeric material that can be coated onto the substrate 400 via a spin-on process and then thermally cured, whereby the photoresist layer 407 may be subsequently applied thereon. In embodiments where the underlayer 405 is an inorganic material, the inorganic material may be a dielectric material formed by any suitable deposition technique, such as CVD, ALD, PVD, spin-on coating, spray coating, etc.

[0040]

[0045] The underlayer 405 functions as a planarization layer, an anti-reflective coat, and / or a photoacid direction control. It can provide etch resistance and line edge roughness control when transferring a pattern into the underlying hard mask layer 403 and target layer 402. The patterning resistance functionality from the underlayer 405 can work together with the underlying hard mask layer 403 during the transfer resist process. In one embodiment, the underlayer 405 does not interact with the photoresist layer 407 and has no interfacial mixing and / or diffusion or cross-contamination with the photoresist layer 407.

[0041]

[0046] The underlayer 405 includes one or more additives, such as an acid agent (e.g., a photoacid generator (PAG) or acid catalyst), a base agent, an adhesion promoter, or a photosensitive component. The one or more additives may be disposed in an organic solvent or a resin and / or inorganic matrix material. Suitable examples of acid agents include photoacid generators (PAGs) and / or acid catalysts selected from the group consisting of sulfonic acids (e.g., p-toluenesulfonic acid, styrenesulfonic acid), sulfonates (e.g., pyridinium p-toluenesulfonate, pyridinium tolylomethanesulfonate, pyridinium 3-nitrobenzenesulfonate), and mixtures thereof. Suitable organic solvents may include homopolymers or higher order polymers containing two or more repeating units and a polymer backbone. Suitable examples of organic solvents include, but are not limited to, propylene glycol methyl ether acetate (PGMEA), ethyl lactate (EL), propylene glycol methyl ether (PGME), propylene glycol n-propyl ether (PnP), cyclohexanone, acetone, gamma butyrolactone (GBL), and mixtures thereof.

[0042]

[0047] In one embodiment, the underlayer 405 provides active acidic, basic, or ironoic / non-ironic species during the lithographic exposure, pre-exposure, or post-exposure bake steps to help control the flow direction of photoacid from the upper photoresist layer 407.

[0043]

[0048] The hard mask layer 403 may be an ARC layer made from the group consisting of silicon oxide, silicon nitride, silicon oxynitride, silicon carbide, amorphous carbon, doped amorphous carbon, TEOS oxide, USG, SOG, organosilicon, oxide containing material titanium nitride, titanium oxynitride, combinations thereof, and the like.

[0044]

[0049] The photoresist layer 407 may be a positive photoresist and / or a negative photoresist that can undergo a chemical amplification reaction. The photoresist layer 407 is a polymer organic material.

[0045]

[0050] As mentioned above, an electric field from electrode 116, as well as a magnetic field from magnet 296, may be applied during the lithographic exposure step, pre-exposure or post-exposure bake step, and particularly the post-exposure bake step. In the embodiment depicted in Figure 4, the electric and / or magnetic fields are applied during the lithographic exposure step. During the lithographic exposure step, optical radiation 412 is directed toward a first region 408 of photoresist layer 407, while a second region 406 of photoresist layer 407 is protected by a photomask 410. In Figure 4, - Photoacid, shown as , is generated in exposed first regions 408 of photoresist layer 407 when a photoacid generator (PAG) is exposed to light radiation 412, such as UV light radiation. However, often the movement of photoacid is generally random, and the photoacid distribution may not be uniformly distributed within first regions 408 or may not be clearly demarcated at interface 430 formed in the plane defining between first region 408 and second region 406 (bounding second region 406), resulting in some of the photoacid drifting and diffusing into second region 406 where photoacid generation is not intended, as shown by arrows 422. As such, lateral photoacid migration (e.g., in a direction parallel to the plane of the substrate 400) can drift into the second region 406, as shown by arrow 422, causing line edge roughness, resolution loss, photoresist footing, profile distortion, and thus causing inaccurate feature transfer to the underlying target layer 402, and / or ultimately resulting in device failure.

[0046]

[0051] It should be noted that although the examples described herein are illustrated as the transfer of electrons from photoacid, any suitable species, including charges, charged particles, photons, ions, electrons, or reactive species in any form, can have a similar effect when an electric field is applied to the photoresist layer 407.

[0047]

[0052] By applying an electric field and / or a magnetic field to the photoresist layer 407, the distribution of the photoacid within the exposed first region 408 can be effectively controlled and the photoacid can be confined within the first region 408. The electric field applied to the photoresist layer 407 can move the photoacid in a vertical direction (e.g., a y direction indicated by arrows 416 and 420, substantially perpendicular to the plane of the substrate 400) with minimal lateral movement (e.g., an x ​​direction indicated by arrow 422) without diffusing into the adjacent second region 406. Generally, the photoacid has a specific polarity that can be influenced by an electric or magnetic field applied thereto, thus orienting the photoacid in a specific direction and thus generating a desired directional movement of the photoacid within the exposed first region 408 without crossing into the adjacent protected second region 406. In one embodiment, the photoacid is further controlled to move longitudinally (e.g., in the z-direction indicated by arrow 428, defined in a plane interconnected with the second region 406 of the photoresist layer 407 protected by the photomask 410) along a lateral plane, as indicated by arrow 414, thereby controlling the longitudinal distribution of the photoacid confined within the exposed first region 408 without intersecting in the x-direction within the second region 406 of the photoresist layer 407, as indicated by arrow 422. A magnetic field generated in the photoresist layer 407 may cause electrons to orbit along certain magnetic field lines, such as the longitudinal direction (e.g., the z-direction indicated by arrow 428), to further control the photoacid in a desired three-dimensional distribution. The interaction between the magnetic and electric fields can optimize the photoacid trajectories in specific paths, as desired, while remaining confined within the exposed first region 408. Furthermore, vertical photoacid movement is desirable to smooth noticeable waves naturally generated by the exposure tool, thereby enhancing exposure resolution. In one embodiment, an electric field having a strength between about 0.1 MV / m and about 100 MV / m can be applied to the photoresist layer 407 during a lithographic exposure step, a pre-baking step, or a post-baking step to confine the photoacid generated in the photoresist layer 407 in a vertical direction, e.g., the y-direction.In one embodiment, a magnetic field between 0.1 Tesla (T) and 10 Tesla (T) can be applied to the photoresist layer 407 during a lithographic exposure step, pre- or post-baking step, along with an electric field, to confine the photoacid generated in the photoresist layer 407 in both longitudinal and vertical directions, e.g., y and z directions, with a minimum lateral (e.g., x) extent. While combining the magnetic field with the electric field, the generated photoacid can be further confined to be distributed longitudinally, e.g., in the direction indicated by arrow 428, remaining in the first region 408 of the photoresist layer 407 and parallel along the interface 430 within the exposed first region 408.

[0048]

[0053] FIG. 5 illustrates another profile of photoacid distribution that can be controlled by utilizing an electric field, a magnetic field, or a combination thereof to specifically control the location of photoacid in specific areas during a post-exposure bake process. The exposed region 502 of the photoresist layer 407 is chemically altered from the first region 408 as shown in FIG. 4 after the lithographic exposure process. After the photoresist layer 407 is lithographically exposed, a post-exposure bake process is performed to harden the photoresist layer 407, including the exposed region 502 and the remaining regions within the photoresist layer 407 (e.g., blocked by a photomask during the lithographic exposure process). During the post-exposure bake process, the amount of an acidic agent (e.g., photoacid), a basic agent, or other suitable additive from the underlayer 405 can be controlled in a manner that can assist in the distribution / migration of the photoacid within the photoresist layer 407 in a desired direction, as indicated by arrows 506 in FIG. 5 . The additive in the lower layer 405 diffuses into the upper photoresist layer 504 during a post-exposure bake step (or even during a lithographic exposure step) and helps improve the sensitivity of the photoresist layer 407 so as to maintain a vertical profile of the photoresist layer 407. As a result, a substantially vertical profile is obtained in the photoresist layer 407 after development and rinsing.

[0049]

[0054] In one embodiment, an additive, such as an acid agent or photoacid, from the lower layer 405 can be thermally driven upward, as indicated by arrow 506, during a post-exposure bake process to efficiently control the profile of the photoresist layer 407. Furthermore, the additive from the lower layer 405 can be driven upward in a specific direction by an electric field, a magnetic field, or a combination thereof during the post-exposure bake process, so that electrons provided by the additive can be controlled to travel in a specific direction, such as a primarily vertical direction, toward the photoresist layer 407. This allows desired vertical structures to be defined and confined within the photoresist layer 407, as needed. Note that the example photoresist layer 407 depicted in FIGS. 4-5 is formed with a straight edge profile (e.g., vertical sidewalls). However, the profile of the photoresist layer 407 can be formed into any desired shape, such as a tapered or flared-out opening, as needed.

[0050]

[0055] After the post-exposure bake step, an anisotropic etching step, or other suitable patterning / etching step, may be performed to transfer features into the underlayer 405, the hard mask layer 403, and the target layer 402, if desired.

[0051]

[0056] 6 depicts a flow diagram of a method 600 for utilizing an underlayer disposed beneath a photoresist layer to assist in controlling photoacid distribution / diffusion within the photoresist layer during a lithographic exposure step or during a pre-exposure bake step or a post-exposure bake step. Method 600 begins in operation 602 by placing a substrate, such as substrate 400 described above, into a processing chamber, such as processing chamber 200 depicted in FIGS. 2-3, with an electrode assembly and a magnetic assembly disposed therein.

[0052]

[0057] In operation 604, after the substrate 400 is positioned, an electric field and / or a magnetic field may be applied individually or collectively to the processing chamber (during the lithography exposure process and / or the post-exposure bake process) to control photoacid migration in the photoresist layer having an underlayer disposed therebelow. After the electric field and / or the magnetic field are applied individually or collectively to the photoresist layer and the underlayer disposed on the substrate, the generated photoacid may move primarily in a vertical, longitudinal, or circular direction, rather than a lateral direction. As a result of the assistance provided by the underlayer disposed below the photoresist layer, photoacid migration in the photoresist layer can be efficiently controlled.

[0053]

[0058] In operation 606, after the exposure step, a post-exposure bake step is performed to harden the photoresist layer and the underlayer. During the bake step, energy (e.g., electrical energy, thermal energy, or other suitable energy) can also be supplied to the underlayer. In one embodiment depicted herein, the energy is thermal energy supplied to the substrate during the post-exposure bake step. Additives from the underlayer can also help control the flow direction of the photoacid within the photoresist layer. By utilizing directional control of the photoacid distribution in a predetermined path with the patterned photoresist layer, a desired edge profile with high resolution, dose sensitivity, resistance to line collapse, and stochastic failure can be obtained, resulting in minimal line edge roughness. In one embodiment, by utilizing the underlayer structure, critical dimension uniformity (CDU) (e.g., critical dimension variation) can be reduced typically to 3 nm to 6 nm, 1 nm to 2 nm, or even less, which is approximately a 50% to 600% uniformity improvement. The line width roughness (LWR) can be generally reduced to 3 nm to 5 nm, 1 nm to 2 nm, or even less, which is about a 50% to 600% roughness improvement. Furthermore, the distance between the first tip edge of the first trench and the second tip edge of the second trench may generally be reduced to 30 nm to 50 nm, or 10 nm to 20 nm. Furthermore, several types of defects, such as corner rounding, footing, deformation profile, and sloped sidewall profile, can also be effectively eliminated or reduced.

[0054]

[0059] The above-described embodiments have many advantages, including the following: For example, the embodiments disclosed herein can reduce or eliminate line edge / width roughness with high resolution and sharp edge profiles. The above-described advantages are exemplary and not limiting. Not all embodiments need to have all advantages.

[0055]

[0060] While the forgoing description is directed to embodiments of the present disclosure, other and further embodiments of the disclosure may be devised without departing from the basic scope thereof, the scope of which is defined by the claims that follow.

Claims

1. A device structure, substrate, and The substrate comprises a multilayer film structure, and the multilayer film structure is A lower layer comprising an organic solvent and an acid selected from the group consisting of sulfonic acids, sulfonates, and mixtures thereof, A photoresist layer comprising a photoacid generator disposed above the lower layer, wherein the photoresist layer is configured to move the photoacid generated from the photoacid generator substantially vertically when exposed to an electric field or magnetic field, and A photomask disposed above the photoresist layer, wherein the photomask is configured to expose a first portion of the photoresist layer not protected by the photomask to radiation light during the lithography exposure process. A device structure that includes this.

2. The device structure according to claim 1, wherein the photomask has an opening that exposes the first portion of the photoresist layer.

3. The device structure according to claim 2, wherein the opening that exposes the first portion of the photoresist layer has a limit dimension between approximately 1 nm and 2 nm.

4. The device structure according to claim 1, wherein the lower layer further comprises one or more additives in an organic polymer solvent.

5. The device structure according to claim 4, wherein the lower layer further comprises an additive including a base agent, an adhesion promoter, and a photosensitive component, or any combination thereof.

6. The device structure according to claim 4, wherein the organic polymer solvent is selected from the group consisting of propylene glycol methyl ether acetate (PGMEA), ethyl lactate (EL), propylene glycol methyl ether (PGME), propylene glycol n-propyl ether (PnP), cyclohexanone, acetone, gamma butyrolactone (GBL), and mixtures thereof.

7. The device structure according to claim 1, wherein the multilayer film structure further includes a hard mask layer disposed below the lower layer and above the substrate.

8. The device structure according to claim 7, wherein the hard mask layer is selected from the group consisting of silicon oxide, silicon nitride, silicon oxynitride, silicon carbide, amorphous carbon, doped amorphous carbon, TEOS oxide, USG, SOG, organosilicon, oxide-containing material titanium nitride, titanium oxynitride, and combinations thereof.

9. The device structure according to claim 1, wherein the lower layer is made of an organic material.

10. A device structure, substrate, and The substrate comprises a multilayer film structure, and the multilayer film structure is The lower layer, the lower layer contains an organic solvent and an acid, A photoresist layer comprising a photoacid generator disposed above the lower layer, wherein the photoresist layer is configured to move the photoacid generated from the photoacid generator substantially vertically when exposed to an electric or magnetic field, thereby forming a plurality of openings within the multilayer film structure having a linewidth roughness (LWR) between approximately 3 nm and approximately 5 nm, and A photomask disposed above the photoresist layer, wherein the photomask is configured to expose a first portion of the photoresist layer not protected by the photomask to radiation light during the lithography exposure process. A device structure that includes this.

11. The device structure according to claim 10, wherein the photomask has an opening that exposes the first portion of the photoresist layer.

12. The device structure according to claim 11, wherein the opening that exposes the first portion of the photoresist layer has a limiting dimension between approximately 1 nm and 2 nm.

13. The device structure according to claim 10, wherein the lower layer further comprises one or more additives in an organic polymer solvent.

14. The device structure according to claim 13, wherein the organic polymer solvent is selected from the group consisting of propylene glycol methyl ether acetate (PGMEA), ethyl lactate (EL), propylene glycol methyl ether (PGME), propylene glycol n-propyl ether (PnP), cyclohexanone, acetone, gamma butyrolactone (GBL), and mixtures thereof.

15. The device structure according to claim 10, wherein the lower layer further comprises an additive including a base agent, an adhesion promoter, and a photosensitive component, or any combination thereof.

16. The device structure according to claim 10, wherein the multilayer film structure further includes a hard mask layer disposed below the lower layer and above the substrate.

17. The device structure according to claim 16, wherein the hard mask layer is selected from the group consisting of silicon oxide, silicon nitride, silicon oxynitride, silicon carbide, amorphous carbon, doped amorphous carbon, TEOS oxide, USG, SOG, organosilicon, oxide-containing material titanium nitride, titanium oxynitride, and combinations thereof.

18. The device structure according to claim 16, wherein the multilayer film structure further includes a target layer disposed below the hard mask layer and above the substrate.

19. The device structure according to claim 10, wherein the lower layer is made of an organic material.

20. The device structure according to claim 10, wherein the photoresist layer is a polymeric organic material.

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