Film structure for electric field-induced photoresist pattern formation process

Abstract

A method and apparatus for minimizing line edge / width roughness of lines formed by photolithography is provided. In one embodiment, a method for treating a substrate includes applying a photoresist layer containing a photoacid generator over 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 includes exposing a first portion of the photoresist layer that is not protected by a photomask in a lithographic exposure step to radiation, 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]

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

Background Art

[0002]

[0002] Integrated circuits have evolved into complex devices that can have millions of components (e.g., transistors, capacitors, and resistors) on a single chip. Photolithography can be used to form components on the chip. Generally, the photolithography process includes several basic steps. First, a photoresist layer is formed on the 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 changes the solubility of the photoresist in the development process when exposed to electromagnetic radiation in a subsequent exposure step. The electromagnetic radiation can have any suitable wavelength, such as a wavelength in the extreme ultraviolet region. The electromagnetic radiation can be from any suitable source, such as an ArF laser at 193 nm, an electron beam, an ion beam, or other sources. Next, in the pre-exposure bake process, excess solvent can be removed.

[0003]

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

[0004]

[0004] After exposure and baking, 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 Figure 1. Figure 1 shows an exemplary top cross-sectional view of a substrate 100 having a patterned photoresist layer 104 placed on a target material 102 to be etched. Openings 106 are defined between the patterned photoresist layers 104, and after the development and rinsing process, the underlying target material 102 is exposed and etched to transfer features onto the target material 102. However, improper control or low resolution of the lithography exposure process can lead to inaccurate limit dimensions of the photoresist layer 104, resulting in unacceptable linewidth roughness (LWR) 108. Furthermore, during the exposure process, the acid generated from the photoacid generator (shown in Figure 1) may randomly diffuse into any region, including areas protected under the mask that are not intended to be diffused, and thus may generate undesirable wiggling or roughness profiles 150 at the edges or interfaces of the patterned photoresist layer 104 interface-connected to the opening 106. The large linewidth roughness (LWR) 108 and undesirable wiggling profiles 150 of the photoresist layer 104 result in inaccurate feature transfer to the target material 102, and thus may ultimately lead to device failure and yield loss.

[0005]

[0005] Therefore, in order to obtain a patterned photoresist layer having the desired limit dimensions, methods and apparatus are needed to control the linewidth roughness (LWR) and increase the resolution as well as dose sensitivity. [Overview of the project]

[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 process or a pre-exposure or post-exposure baking process. In one embodiment, the device structure includes a film structure disposed on a substrate and a plurality of openings formed in the film structure, the openings formed across the substrate having a limit dimensional uniformity of about 1 nm to 2 nm.

[0007]

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

[0008]

[0008] In yet another embodiment, a method for processing a substrate includes adding a photoresist layer on a lower layer placed on the substrate, exposing a first portion of the photoresist layer not protected by a photomask to radiation light in a lithography exposure step, performing a baking step on the photoresist layer and the lower layer, and applying an electric or magnetic field while performing the baking step.

[0009]

[0009] In order to provide a detailed understanding of the features of the present disclosure described above, the present disclosure, which has been briefly summarized above, will be described in more detail with reference to embodiments, some of which are illustrated in the accompanying drawings. However, it should be noted that the accompanying drawings show only typical embodiments of the present disclosure, and therefore the present disclosure may allow for other equally valid embodiments, and should not be considered to limit the scope of the present disclosure. [Brief explanation of the drawing]

[0010] [Figure 1]

[0010] A top view of an exemplary structure of a patterned photoresist layer placed on a conventional substrate is shown. [Figure 2]

[0011] This is a schematic cross-sectional view of an apparatus for processing substrates according to one embodiment. [Figure 3]

[0012] Figure 2 is a top view of one embodiment of an electrode assembly located within the apparatus. [Figure 4]

[0013] This diagram illustrates the control of the acid distribution in the photoresist layer placed on the film structure during the exposure process. [Figure 5]

[0014] This diagram illustrates the control of the acid distribution in the photoresist layer on a film structure having a desired profile during the post-exposure baking process. [Figure 6]

[0015] This is a flowchart illustrating one method for controlling the acid distribution in the photoresist layer during the exposure process. [Modes for carrying out the invention]

[0011]

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

[0012]

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

[0013]

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

[0014]

[0019] The processing chamber 200 may be an independent, standalone processing chamber. Alternatively, the processing chamber 200 may be part of a processing system, such as an inline processing system, a cluster processing system, or a track processing system, as needed. The processing chamber 200 is described in detail below and may be used for pre-exposure baking, post-exposure baking, and / or other processing steps.

[0015]

[0020] The processing chamber 200 includes a chamber wall 202, an electrode assembly 216, and a substrate support assembly 238. The chamber wall 202 includes a side wall 206, a lid assembly 210, and a bottom 208. The chamber wall 202 partially encloses the processing space 212. The processing space 212 is accessed through a substrate transfer port (not shown) configured to facilitate the movement of the substrate 240 in 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 allow the transfer of the substrate 240 in and out of an adjacent transfer chamber.

[0016]

[0021] A pumping port 214 may optionally be located through the lid assembly 210, side wall 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 pump components, such as a vacuum pump. The pumping component reduces the pressure in the processing space 212, allowing any gases and / or process byproducts to be discharged from 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 located within the processing chamber 200. The substrate support assembly 238 supports the substrate 240 during processing. The substrate support assembly 238 may comprise a body 224 enclosing 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 located within the substrate support assembly 238. The heater 232 controls the heating of the substrate support assembly 238 and the substrate 240 placed on it to a predetermined temperature. The heater 232 is configured to rapidly raise the temperature of the substrate 240 at a constant rate and to precisely 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, supply 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 within the processing chamber 200, such as from the chamber wall, chamber liner, or edge rings circumscribing the substrate or chamber ceiling, as needed to supply thermal energy to the substrate 240 placed 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 around the z-axis. The substrate support assembly 238 may be configured to rotate continuously or at a constant rate, or it may be configured to rotate in a stepwise or indexing manner. For example, the substrate support assembly 238 may rotate by a predetermined amount, such as 90 degrees, 180 degrees, or 270 degrees, and then the rotation may be stopped 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 to the second surface 226. The first surface 234 is configured to support the substrate 240. A stem 242 is connected 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 the exposure step of the photolithography process. The photoresist layer 250 has a latent image line 255 formed internally from the exposure step. The latent image lines 255 may 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 connected to a lift system (not shown) for moving the substrate support assembly 238 between a raised processing position (as shown) and a lowered substrate transport position. The lift system can precisely and tightly control the position of the substrate 240 in the z direction. In some embodiments, the lift system may 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 conduits for electrical and thermocouple conductors between the substrate support assembly 238 and other components of the processing chamber 200. A vacuum seal is provided between the processing space 212 and the atmosphere outside the processing chamber 200, and a bellows 246 is connected to the substrate support assembly 238 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 the gas supplied by the source 204 can enter the processing chamber 200. Optionally, the source 204 can controllably pressurize the processing space 212 using a gas such as nitrogen, argon, helium, other gases, or combinations thereof. A controlled environment can be created within the processing chamber 200 by the gas from the source 204. 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. As used herein, the x and y directions are referred to as the lateral direction or lateral dimension. The actuator 290 enables the electrode assembly 216 to scan the surface of the substrate 240. The actuator 290 also enables 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 can be coupled to the inside of the bottom 208 of the processing chamber 200, the second surface 226 of the substrate support assembly 238, or the stem 242. In still other embodiments, the electrode assembly 216 can 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 supplying power to the substrate support is a dual-pole power supply that switches between positive and negative bias. In some embodiments, the power supply 270 or 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 power supply 275 may be connected to the first electrode 258, the second electrode 260, and the substrate support assembly 238. In such embodiments, the pulse delays to the first electrode 258, the second electrode 260, and the substrate support assembly 238 may differ. The electrode assembly 216 may be configured to generate an electric field parallel to the 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 the y direction, the x direction, or one of the other directions in the x-y plane.

[0022]

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

[0023]

[0028] In some embodiments, any or all of power supplies 270, 274, and 275 may use a DC offset. The DC offset can 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 the first electrode 258 and the second electrode 260 are negatively pulsed, the substrate support assembly 238 is also negatively pulsed. In these embodiments, the first electrode 258, the second electrode 260, and the substrate support assembly 238 are synchronized but offset in time. For example, the first electrode 258 can be in a "1" state while the substrate support assembly is in a "0" state, and then the substrate support assembly 238 can be in a "1" state while the first electrode 258 is in a "0" state.

[0024]

[0029] The electrode assembly 216 extends approximately across 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 can extend between about 10% and about 80% of the width of the substrate support assembly 238, such as between about 20% and about 40%. In embodiments where the width of the electrode assembly 216 is smaller than the width of the substrate support assembly 238, the actuator 290 can scan the electrode assembly 216 across the surface of the substrate 240 disposed on the first surface 234 of the substrate support assembly 238. For example, the actuator 290 can scan such that the electrode assembly 216 scans across the entire surface of the substrate 240. In other embodiments, the actuator 290 can scan only a portion of the substrate 240. Instead, the substrate support assembly 238 can scan under the electrode assembly 216.

[0025]

[0030] In some embodiments, one or more magnets 296 can be placed inside the processing chamber 200. In the embodiment shown in Figure 2, the magnets 296 are connected to the inner surface of the side wall 206. In other embodiments, the magnets 296 may be located elsewhere inside the processing chamber 200 or outside the processing chamber 200. The magnets 296 may be, for example, permanent magnets or electromagnets. Typical permanent magnets include ceramic magnets and rare-earth magnets. In embodiments in which the magnets 296 include electromagnets, the magnets 296 may be connected to a power source (not shown). The magnets 296 are configured to generate a magnetic field perpendicular to or parallel to the direction of the electric field lines generated by the electrode assembly 216 on the first surface 234 of the substrate support assembly 238. For example, the magnets 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 Figure 2) and polarized species (not shown) generated by the photoacid generator in the photoresist layer 250 in directions perpendicular to the magnetic field, such as parallel to the latent image line 255. By driving the charged species 355 and polarized species in directions parallel to the latent image line 255, line roughness can be reduced. The uniform movement of the charged species 355 and polarized species is shown by the double-headed arrow 370 in Figure 3. In contrast, when no magnetic field is applied, the charged species 355 and polarized species may move randomly, as shown by the arrow 370'.

[0026]

[0031] Continuing to refer to Figure 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 of the first electrode 258, the first support structure 330, and the one or more antennas 320 may form a single body. Alternatively, the first electrode 258 may include separate parts that can be connected 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 consist 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 can be manufactured by machining, casting, or additive manufacturing.

[0027]

[0032] The first support structure 330 may be made from a conductive material such as a metal. For example, the first support structure 330 may be made from 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, for example, between about 100 mm and about 300 mm. In some embodiments, the first support structure 330 has a length L approximately equal to the diameter of a standard semiconductor substrate. In other embodiments, the first support structure 330 has a length L greater than or less than the diameter of a standard semiconductor substrate. For example, in various representative embodiments, the length L of the first support structure 330 may 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 may 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 may be between about 1 mm and about 10 mm, such as about 5 mm, or between about 2 mm and about 8 mm. In some embodiments, the first support structure 330 may be square, cylindrical, rectangular, oval, rod-shaped, or other shapes. Embodiments having a curved outer surface can avoid arc discharge.

[0028]

[0033] The first support structure 330 may be made from the same material as the second support structure 331. The dimensional range suitable for the first support structure 330 is 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] One or more antennas 320 of the first electrode 258 may also be made from a conductive material. One or more antennas 320 may be made from the same material as the first support structure 330. One or more antennas 320 of the first electrode 258 may have any desired dimensions. For example, the length L1 of one or more antennas 320 may be between about 25 mm and about 450 mm, for example, between about 100 mm and about 300 mm. In some embodiments, the first support structure 330 has a length L1 approximately equal to the diameter of a standard substrate. In other embodiments, the length L1 of one or more antennas 320 may be between about 75% and 90% of the diameter of a standard substrate. The width W1 of one or more antennas 320 may be between about 2 mm and about 25 mm. In other embodiments, the width W1 of one or more antennas 320 is less than about 2 mm. In other embodiments, the width W1 of one or more antennas 320 is greater than 25 mm. The thickness of one or more antennas 320 can be between approximately 1 mm and 10 mm, such as between approximately 2 mm and approximately 8 mm. One or more antennas 320 may have a cross-section that is square, rectangular, oval, circular, cylindrical, or of another shape. Embodiments having a rounded outer surface can avoid arc discharge.

[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 from one or more of the other antennas 320. For example, some of the one or more antennas 320 may have a different length L1 from 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 may be made from the same range of material 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] Antenna 320 may include a number of antennas 320 between 1 and about 40. For example, antenna 320 may include a number of antennas 320 between about 4 and about 40, such as a number of antennas 320 between about 10 and about 20. In other embodiments, antenna 320 may include a number of antennas 320 greater than 40. In some embodiments, each of the antennas 320 may be substantially perpendicular to the first support structure 330. For example, in embodiments where 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. Distances C and C' may be between approximately 1 mm and approximately 10 mm, respectively. In other embodiments, distances C and C' may be less than approximately 1 mm or greater than approximately 10 mm. In some embodiments, distances C and C' are equal. In other embodiments, distances C and C' are different.

[0034]

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

[0035]

[0040] A distance B is defined between the opposing surfaces of one of the antennas 320 and one of the adjacent antennas 321. Distance B can be greater than, for example, about 1 mm. For example, distance B could be between about 2 mm and about 10 mm, such as between about 4 mm and about 6 mm. The distance B defined between them may be the same, each distance B may be different, or some distance B may be the same and some distance B may be different. By adjusting distance B, the electric field strength can be easily controlled.

[0036]

[0041] Antennas 320 and 321 may be oriented in an alternating arrangement above the photoresist layer 250. For example, the antenna 320 of the first electrode 258 and the antenna 321 of the second electrode 260 may be arranged such that at least one of the antennas 320 is positioned between two of the antennas 321. In addition, at least one antenna 321 may be positioned between two of the antennas 320. In some embodiments, all but one of the antennas 320 are positioned between two of the antennas 321. In these embodiments, all but one of the antennas 321 are positioned between two of the antennas 320. In some embodiments, antennas 320 and antennas 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 may be a contact between the first electrode 358 and a power supply 270, a power supply 275, or ground. The second terminal 311 may be a contact between the second electrode 260 and a power supply 270, a power supply 275, or ground. The first terminal 310 and the second terminal 311 are shown as being located 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 may 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 from the first support structure 330 and the second support structure 331, respectively. In other embodiments, the first terminal 310 and the second terminal 311 may generally have the same shape and size as the first support structure 330 and the second support structure 331, respectively.

[0038]

[0043] During operation, a voltage may be supplied from a power source such as power supply 270, power supply 274, or power supply 275 to the first terminal 310, the second terminal 311, and / or the substrate support assembly 238. 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 one of the one or more antennas 320 and an adjacent antenna of the one or more antennas 321. Due to the alternating and aligned spatial relationship of the antennas 320 and 321, the electric field is generated 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 line 255 is parallel to the electric field line generated by the electrode assembly 216. Since the charged species 355 is charged, the charged species 355 is affected by the electric field. The charged species 355 generated by the photoacid generator within the photoresist layer 250 are driven in the direction of the electric field. By driving the charged species 355 in a direction parallel to the latent image line 255, line edge roughness can be reduced. Its uniform directional movement is illustrated by the double arrow 370. In contrast, if 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] Figure 4 depicts a film structure 404 placed on a substrate 400 during the lithography exposure process. A photoresist layer 407 is placed on the film structure 404. The film structure 404 includes a lower layer 405 placed on a target layer 402, on top of a hard mask layer 403. The target layer 402 is then patterned to form desired device features within the target layer 402. In one embodiment, the lower layer 405 may be an organic material, an inorganic material, or a mixture of organic and inorganic materials. In embodiments where the lower layer 405 is an organic material, the organic material may be a crosslinkable polymer material that can be coated onto the substrate 400 via a spin-on process and then thermocured. The photoresist layer 407 can then be added thereon. In embodiments where the lower layer 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, or spray coating.

[0040]

[0045] The lower layer 405 functions as a planarization layer, an anti-reflective coating, and / or a photo-acid direction control. It can provide etching resistance and edge roughness control when transferring the pattern into the underlying hard mask layer 403 and target layer 402. The patterning resistance functionality from the lower layer 405 can work together with the underlying hard mask layer 403 during the resist process transfer. In one embodiment, the lower layer 405 does not interact with the photoresist layer 407 and does not have interfacial mixing and / or diffusion or cross-contamination with the photoresist layer 407.

[0041]

[0046] The lower layer 405 contains one or more additives, such as an acidifying agent (e.g., a photoacid generator (PAG) or an acid catalyst), a base agent, an adhesion promoter, or a photosensitive component. One or more additives may be placed in an organic solvent or a resin and / or inorganic matrix material. Suitable examples of acidifying 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 tolyllomethanesulfonate, pyridinium 3-nitrobenzenesulfonate), and mixtures thereof. Suitable organic solvents may include homopolymers or higher-order polymers containing two or more repeating units and polymer backbone chains. 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 lower layer 405 provides an active acid agent, a base agent, or ironoic / non-ironic species during the lithography exposure process, or pre-exposure or post-exposure baking process, to help control the direction of photoacid flow 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, and combinations thereof.

[0044]

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

[0045]

[0050] As described above, an electric field from the electrode 116 may be applied during the lithography exposure process, the pre-exposure or post-exposure baking process, and especially the post-exposure baking process, as well as a magnetic field from the magnet 296. In the embodiment shown in Figure 4, an electric field and / or a magnetic field are applied during the lithography exposure process. During the lithography exposure process, the light emission 412 is directed to a first region 408 of the photoresist layer 407, while a second region 406 of the photoresist layer 407 is protected by the photomask 410. - The photoacid shown is generated in the exposed first region 408 of the photoresist layer 407 when the photoacid generator (PAG) is exposed to light radiation 412 such as UV light radiation. However, often the migration of the photoacid is generally random, and the photoacid distribution may not be uniform within the first region 408, or a clear boundary may not be established at the interface 430 formed in the plane that defines the boundary between the first region 408 and the second region 406 (bordering the boundary with the second region 406). As a result, as shown by arrow 422, some of the photoacid drifts and diffuses into the second region 406 where the generation of photoacid is not intended. Thus, lateral photoresist migration (e.g., in a direction parallel to the plane of the substrate 400) drifts into the second region 406, as indicated by arrow 422, causing edge roughness, loss of resolution, photoresist fitting, and profile deformation, which in turn can lead to inaccurate feature migration to the underlying target layer 402 and / or ultimately to device failure.

[0046]

[0051] Although the examples described herein illustrate electron transfer from photoacid, it should be noted that any suitable species, including charges, charged particles, photons, ions, electrons, or any form of reactive species, may 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 photoacid within the exposed first region 408 can be efficiently 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., the y direction, indicated by arrows 416 and 420, substantially perpendicular to the plane of the substrate 400) with minimal lateral movement (e.g., the 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 the electric or magnetic field applied to it, and therefore the photoacid can be oriented in a specific direction, thus generating the 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 (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, 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. The magnetic field generated in the photoresist layer 407 may cause electrons to orbit along certain magnetic field lines, such as longitudinally (in 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, if desired, optimize the trajectory of the photoacid in a particular path and confine it within the exposed first region 408. Furthermore, it is desirable that the perpendicular photoacid movement smooths out the prominent waves naturally generated by the exposure tool, thereby increasing the exposure resolution. In one embodiment, an electric field having an intensity between approximately 0.1 MV / m and approximately 100 MV / m can be applied to the photoresist layer 407 during the lithography exposure process, pre-baking process, or post-baking process to restrict the photoacid generated within the photoresist layer 407 to the vertical direction, for example, the y-direction.In one embodiment, a magnetic field between 0.1 Tesla (T) and 10 Tesla (T), along with an electric field, can be applied to the photoresist layer 407 during the lithography exposure process, pre- or post-baking process, to restrict the photoacid generated within the photoresist layer 407 to a minimum transverse range (e.g., x-direction) in both the longitudinal and perpendicular directions, for example, in the y and z directions. While combining the electric and magnetic fields, the generated photoacid may also be further restricted to be distributed longitudinally, for example, in the direction indicated by arrow 428, remaining in the first region 408 of the photoresist layer 407 and parallel to the interface 430 within the exposed first region 408.

[0048]

[0053] Figure 5 illustrates another profile of the photoacid distribution, which can be controlled by utilizing an electric field, a magnetic field, or a combination thereof, to specifically control the location of photoacid in a particular area during the post-exposure baking process. The exposed region 502 of the photoresist layer 407 is chemically altered from the first region 408 after the lithography exposure process, as shown in Figure 4. After the photoresist layer 407 is exposed by lithography, a post-exposure baking process is performed to cure the photoresist layer 407, including the exposed region 502 and the remaining region within the photoresist layer 407 (e.g., shielded by a photomask during the lithography exposure process). During the post-exposure baking process, an acidifying agent (e.g., photoacid), a basic agent, or other suitable additive from the underlying layer 405 can be controlled in such a way that it can help the distribution / migration of photoacid within the photoresist layer 407 in a desired direction, as indicated by the arrow 506 in Figure 5. The additives in the lower layer 405 diffuse into the upper photoresist layer 504 during the post-exposure baking process (or even during the lithography exposure process), helping to improve the sensitivity of the photoresist layer 407 so as to maintain its vertical profile. As a result, after development and rinsing, a substantially vertical profile is obtained within the photoresist layer 407.

[0049]

[0054] In one embodiment, to efficiently control the profile of the photoresist layer 407, an additive such as an acid or photoacid from the lower layer 405 can be thermally driven upward as indicated by arrow 506 during the post-exposure baking process. Furthermore, the additive from the lower layer 405 may be driven upward in a specific direction by an electric field, a magnetic field, or a combination thereof during the post-exposure baking process, so that the electrons supplied by the additive can be controlled to move along a specific path, such as primarily vertically toward the photoresist layer 407. In this way, a desired vertical structure can be defined and confined within the photoresist layer 407 as needed. Note that the embodiments of the photoresist layer 407 depicted in Figures 4-5 are formed with a linear 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 flare-out opening, as needed.

[0050]

[0055] After the post-exposure baking process, an anisotropic etching process or other suitable patterning / etching process may be performed, if necessary, to transfer features to the lower layer 405, the hard mask layer 403, and the target layer 402.

[0051]

[0056] Figure 6 shows a flowchart of method 600 for assisting in the control of photoacid distribution / diffusion within the photoresist layer during the lithography exposure process, pre-exposure baking process, or post-exposure baking process, by utilizing an underlying layer placed beneath the photoresist layer. Method 600 is started in operation 602 by placing a substrate, such as the aforementioned substrate 400, inside a processing chamber, such as the processing chamber 200 shown in Figures 2 and 3, with an electrode assembly and a magnetic assembly placed inside.

[0052]

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

[0053]

[0058] In operation 606, after the exposure step, a post-exposure baking step is performed to cure the photoresist layer and the underlying layer. During the baking step, energy (e.g., electrical energy, thermal energy, or other suitable energy) can also be supplied to the underlying layer. In one embodiment described herein, this energy is thermal energy supplied to the substrate during the post-exposure baking step. Additives from the underlying layer can also help control the direction of photoacid flow within the photoresist layer. By utilizing the control of the direction of photoacid distribution in a given path having a patterned photoresist layer, a desired edge profile with high resolution, dose sensitivity, resistance to line collapse, and stochastics failure following a probability distribution can be obtained, resulting in minimum edge roughness. In one embodiment, by utilizing the underlying layer structure, critical dimensional uniformity (CDU) (e.g., variability in critical dimensions) can generally be reduced from 3 nm to 6 nm, 1 nm to 2 nm, or less, which is an improvement in uniformity of about 50% to 600%. Line width roughness (LWR) can generally be reduced to 3 nm to 5 nm, 1 nm to 2 nm, or even less, which represents a roughness improvement of approximately 50% to 600%. 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. In addition, several types of defects such as corner rounding, footing, deformation profiles, and sloping sidewall profiles can also be efficiently eliminated and reduced.

[0054]

[0059] The embodiments described above have many advantages, including the following. For example, the embodiments disclosed herein can reduce or eliminate edge / width roughness having high resolution and sharp edge profiles. The advantages described above are illustrative and not limiting. Not all embodiments are required to have all of these advantages.

[0055]

[0060] While the above description applies to embodiments of the present disclosure, other embodiments and further embodiments of the present disclosure may be devised without departing from the basic scope of the present disclosure, and the scope of the present disclosure is defined by the following claims.

Claims

1. A method for processing a substrate, The process involves adding a photoresist layer containing a photoacid generator to a multilayer arranged on a substrate, wherein the multilayer includes a lower layer containing the photoacid generator and in contact with the photoresist layer. Exposing the first portion of the photoresist layer that is not protected by the photomask to radiation light in a lithography exposure process, and By applying an electric or magnetic field, the photoacid generated from the photoacid generator in the lower layer is moved to the photoresist layer, and the movement of the photoacid within the photoresist layer is substantially changed in a vertical direction. Methods that include...

2. Baking the photoresist layer and the lower layer, The method according to claim 1, further comprising applying an electric field or a magnetic field while baking the photoresist layer and the underlying layer.

3. The method according to claim 1, wherein the electric field or the magnetic field is applied to the photoresist layer during the lithography exposure process.

4. The method according to claim 2, further comprising performing a pre-baking step on the photoresist layer and the underlying layer disposed on the substrate, wherein the electric field or the magnetic field is applied to the photoresist layer during the pre-baking step.

5. The method according to claim 1, wherein the lower layer contains the photoacid generator in an organic polymer solvent.

6. The method according to claim 5, 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 method according to claim 1, wherein the multilayer further includes a hard mask layer disposed below the lower layer and on the substrate.

8. The method 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. A method for processing a substrate, Adding a photoresist layer that is located on a lower layer containing a photoacid generator placed on a substrate and is in contact with the lower layer, Exposing the first portion of the photoresist layer that is not protected by the photomask to radiation light in a lithography exposure process, Performing a baking process on the photoresist layer and the lower layer, A method comprising applying an electric or magnetic field while performing the baking step to move the photoacid generated from the photoacid generator in the lower layer to the photoresist layer, thereby substantially changing the movement of the photoacid in the photoresist layer in a vertical direction.

10. Exposing the first portion of the photoresist layer is The method according to claim 9, further comprising applying an electric field or a magnetic field while performing the lithography exposure step.

11. The method according to claim 9, wherein the lower layer is an organic material.

12. The method according to claim 11, wherein the lower layer contains the photoacid generator in an organic solvent.

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