METHOD FOR INFILTRATION OF METAL OXIDE INTO PHOTORESIST - Patent application

Abstract

Disclosed herein is a method for forming a metal oxide in a photoresist to improve profile control. The method includes infiltrating a metal oxide into a photoresist layer by pressing a methyl-containing material in a processing environment proximate to the film stack. The film stack includes a photoresist layer, the photoresist layer being disposed over and in contact with an underlying layer. The underlying layer is disposed over a substrate. The method includes etching the film stack including the photoresist layer implanted with the metal oxide.

Description

[Technical Field]

[0001] Examples of the present disclosure generally relate to methods for enhancing photoresist profile control. In particular, examples of the present disclosure provide methods for forming metal oxides in photoresist to improve profile control. [Background technology]

[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. Typically, the photolithography process involves forming a photoresist layer on a substrate. The 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 during a development process when exposed to electromagnetic radiation in a subsequent exposure stage. The electromagnetic radiation can have any suitable wavelength, such as a wavelength in the extreme ultraviolet range, and can be from any suitable radiation source, such as a 193 nm ArF laser, electron beam, ion beam, or other radiation source. Excess solvent can then be removed during a pre-exposure bake process.

[0003] During the exposure stage, a photomask or reticle can be used to selectively expose specific areas of a photoresist layer disposed on a substrate to electromagnetic radiation. Other exposure methods may be maskless exposure methods. Exposure to light can decompose a photoacid generator, thereby generating acid, and a hidden acid image is obtained 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 the subsequent development process.

[0004] After the post-exposure bake, the substrate and photoresist layer are developed and rinsed. A patterned photoresist layer is then subsequently formed on the substrate. After the development and rinsing process, openings are defined in the patterned photoresist layer, thereby exposing the underlying target material, which is etched to transfer features onto the target material. Factors such as imprecise control or low resolution of the lithography exposure process or the elastic energy of the patterned layer can cause poor critical dimensions in the patterned photoresist layer, resulting in unacceptable line width roughness (LWR). High line width roughness (LWR) in the patterned photoresist layer can cause inaccurate feature transfer to the target material, ultimately resulting in premature device failure and yield loss. Summary of the Invention

[0005] Therefore, there is a need for improved patterned photoresist layers.

[0006] Examples of the present disclosure relate to methods for forming metal oxides in photoresist to improve profile control. In one example, a method for infiltrating a photoresist layer is disclosed. The method includes forming a metal oxide in the photoresist layer by pressing a methyl-group-containing material in a processing environment proximate a film stack. The film stack includes a photoresist layer disposed over and in contact with an underlying layer. The underlying layer is disposed over a substrate. The method further includes etching the film stack including the photoresist layer implanted with the metal oxide.

[0007] In another example, a method for infiltrating a photoresist layer includes pressurizing a methyl-containing material in a processing environment adjacent a film stack. The film stack includes a photoresist layer disposed over and in contact with an underlying layer. The underlying layer is disposed over a substrate. The method further includes heating the methyl-containing material to a predetermined temperature and converting the methyl-containing material to a metal oxide in the photoresist layer. The method includes etching the film stack including the photoresist layer implanted with the metal oxide.

[0008] In yet another example, a semiconductor processing system is provided that includes a semiconductor processing chamber. A non-transitory computer-readable medium stores instructions that, when executed by a processor, result in a method being performed in the semiconductor processing chamber. The method includes forming a metal oxide in a photoresist layer by pressing a methyl-containing material in a processing environment proximate a film stack. The film stack includes a photoresist layer disposed over and in contact with an underlying layer. The underlying layer is disposed over a substrate. The method includes etching the film stack, including the photoresist layer implanted with the metal oxide.

[0009] Thus, in order that the above-described features of examples of the present disclosure may be understood in detail, the more particular description of the present disclosure briefly summarized above will in some cases refer to examples, some of which are illustrated in the accompanying drawings. It should be noted, however, that the accompanying drawings merely illustrate typical examples of the present disclosure, which may admit of other equally effective examples, and therefore the accompanying drawings should not be considered as limiting the scope of the present disclosure. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 illustrates an exemplary processing chamber configured to perform patterning and etching of a substrate. [Figure 2] 2 is a flowchart of a method for patterning a film stack disposed over the substrate shown in FIG. 1. [Figure 3A-3B] FIG. 10 is a cross-sectional view of a film stack during patterning and etching of the film stack. [Figure 3C-3E] FIG. 10 is a cross-sectional view of a film stack during patterning and etching of the film stack. DETAILED DESCRIPTION OF THE INVENTION

[0011] For ease of understanding, where possible, identical reference numerals have been used to designate identical elements common to the figures, and it is contemplated that elements disclosed in one example may be conveniently utilized in other examples without specific recitation.

[0012] Examples of the present disclosure relate to methods for forming metal oxides in photoresist to improve profile control. The methods disclosed herein are directed to the formation or infiltration of metal oxides into a photoresist layer.

[0013] In conventional resist layers, the resist material is selected from polymers to control parameters such as selectivity and linewidth roughness when the film stack on which the resist layer is formed is exposed to an etchant, and a via or trench is formed in the lower layer of the film stack. However, when the resist layer is selected from polymers and the lower layer is formed from a complex metal or amorphous compound, undercuts may form at the interface between the resist layer and the lower layer. Conventional approaches to improving selectivity sometimes require the deposition of multiple resist layers or require improvements to the polymer structure of each resist layer. However, conventional approaches sometimes require changing the composition of the photoresist depending on the size of the features intended to be patterned.

[0014] According to the method disclosed herein, a metal oxide is formed in a patterned photoresist layer. A methyl-containing material is introduced into a semiconductor processing chamber having a film stack disposed therein. The methyl-containing material can also include one of aluminum, hafnium, or zirconium. In one example, the film stack includes a substrate, an underlayer disposed on the substrate, and a patterned photoresist layer disposed on the underlayer. The film stack, and thus the patterned photoresist layer, is heated to absorb the methyl-containing material into the patterned photoresist layer. The processing environment is subsequently purged, and the film stack is exposed to an oxidizing agent, such as H2O. The oxidizing agent is heated under pressure to form water or water vapor on the film stack. The oxidizing agent is absorbed into the patterned photoresist layer, oxidizing the absorbed methyl-containing material. Upon oxidation, the methyl-containing material forms a metal oxide in the patterned photoresist layer. When the methyl-containing material is a tri-methylaluminum (TMA) precursor introduced into the processing environment and subsequently purged and pumped, a single pre-etch process is performed, i.e., HO is introduced into the processing environment without repeated introduction of TMA prior to the oxidation and etching of the film stack. The pre-etch process can include any one or all of the processes of the disclosed method (discussed in detail below) prior to the etching of the film stack. Advantageously, the single pre-etch process can infiltrate the metal oxide into the photoresist layer by between about 20 nm and about 40 nm. Furthermore, the metal oxide is crosslinked throughout the entire thickness of the patterned photoresist. Repeating one or all of the pre-etch processes prior to the etching of the film stack stops the infiltration of the methyl-containing material through the thickness of the photoresist layer, thereby stopping the infiltration of the metal oxide. In this case, in some examples disclosed herein, the entire method, i.e., the complete cycle including the pre-etch process and etching of the film stack, can be repeated.

[0015] The methods disclosed herein are feature size independent. Advantageously, metal oxide infiltration into the underlayer can achieve a critical dimension change of less than 1 nm, with a linewidth roughness change of less than 0.4 nm. Therefore, the method of metal oxide infiltration into a polymer ensures that the metal oxide does not infiltrate into the underlayer by controlling the properties of the photoresist layer, including its density, relative to the properties of the underlayer. For example, the photoresist can be selected from low-density carbonyl-based materials, and the underlayer can be selected from high-density materials such as silicon, germanium, gallium, or their derivatives, including each of the materials disclosed in the information in paragraph

[0039] .

[0016] 1 is a simplified cross-sectional view of a processing chamber 100, such as a dual load lock chamber. It is understood that processing chamber 100 is exemplary and that other processing chambers may be adapted to perform the methods disclosed herein.

[0017] Additionally, the processing chamber 100 is suitable for performing deposition processes. One example of a processing chamber that can be adapted to benefit from the present disclosure is the CENTRIS® Sym3™ etch processing chamber, available from Applied Materials, Inc., Santa Clara, California. The processing chamber can also be configured for deposition, particularly atomic layer deposition (ALD). One example of an ALD tool is the iSprint™ ALD / CVD SSW chamber configured using a Centura® system or an Endura® system.

[0018] The processing chamber 100 includes an upper chamber volume 120 for transferring and processing a substrate 138, and a lower chamber volume 110 for transferring the substrate 138. The upper chamber volume 120 and the lower chamber volume 110 are vertically stacked and isolated from each other. Each of the lower and upper chamber volumes 110, 120 can be selectively connected to two adjacent external environments (i.e., a factory interface and a transfer chamber, neither of which are shown) via two openings configured for transferring substrates. Example substrate sizes include 200 mm diameter, 250 mm diameter, 300 mm diameter, and 450 mm diameter, among others.

[0019] The processing chamber 100 includes a chamber body 103. In one example, the chamber body 103 includes an upper chamber body 121 and a lower chamber body 111, which are coupled together to define lower and upper chamber volumes 120, 110. The processing chamber 100 can include a hoop assembly 144 configured to confine a containment region within the upper chamber volume 120 and to load and unload substrates. While the hoop assembly 144 is described in the context of a load lock chamber having a processing volume, it will be understood that the hoop assembly 144 can be utilized in any suitably adapted load lock and / or processing chamber, including a load lock chamber having a single processing volume, where a symmetrical containment region is desired. The processing chamber 100 can include support pins 113 for supporting a substrate 138 within the lower chamber volume 110.

[0020] The upper chamber volume 120 is defined by a sidewall 124 of the upper chamber body 121, a bottom wall 123 of the upper chamber body 121, and a top wall 118 of the lower chamber body 111, as well as a chamber lid assembly 116. The upper chamber volume 120 is suitable for patterning a material layer, forming, and etching a material layer disposed over a substrate 138. In examples not shown, it is also contemplated that one or more plasma generators may optionally be utilized to maintain a plasma in the upper chamber volume 120 in place of or in addition to a remote plasma source. Other processing chambers, including processing chambers from other manufacturers, are contemplated for adaptation to practice examples of the present disclosure.

[0021] A substrate support pedestal 140 is disposed within the upper chamber volume 120 to support a substrate 138 during processing. A cover ring 130 is disposed above the ESC 134 and along the periphery of the substrate support pedestal 140. The cover ring 130 is configured to confine etching gas to a desired portion of the exposed top surface of the substrate 138, while shielding the top surface of the substrate support pedestal 140 from the plasma environment inside the processing chamber 100. Lift pins (not shown) are selectively moved through the substrate support pedestal 140 to lift the substrate 138 above the substrate support pedestal 140 to facilitate access to the substrate 138 by a transfer robot (not shown) or other suitable transfer mechanism.

[0022] The substrate support pedestal 140 includes an electrostatic chuck (ESC) 134 for holding the substrate 138 during processing. The ESC 134 uses electrostatic attraction to hold the substrate 138 to the substrate support pedestal 140. The ESC 134 is powered by an RF power supply 154 integrated with a matching network 152. The ESC 134 includes an electrode 132 embedded within a dielectric body. The electrode 132 is coupled to the RF power supply 154 to provide a bias that attracts plasma ions formed by the process gas in the upper chamber volume 120 to the ESC 134 and the substrate 138 disposed thereon. The RF power supply 154 can be cycled on and off, i.e., pulsed, during processing of the substrate 138. The plasma generator can be an RF-driven coil located outside or within the upper chamber volume 120 and / or an RF-driven electrode located within the substrate support pedestal 140.

[0023] The ESC 134 may include a heater disposed therein and connected to a power source (not shown) for heating the substrate, while the cooling base 136 supporting the ESC 134 may include conduits for circulating a heat transfer fluid to maintain the temperature of the ESC 134 and the substrate 138 disposed thereon. The ESC 134 is configured to perform at a temperature range desired by the thermal budget of devices fabricated on the substrate 138. For example, the ESC 134 may be configured to maintain the substrate 138 at a temperature of about −25 degrees Celsius to about 150 degrees Celsius, such as between about 50 degrees Celsius and about 100 degrees Celsius.

[0024] The cooling base 136 is provided to help control the temperature of the substrate 138. The cooling base 136 can maintain a substantially constant temperature of the substrate 138 to reduce process variations and time. In one example, the temperature of the substrate 138 is maintained at approximately 30 degrees Celsius to 120 degrees Celsius throughout the subsequent cleaning process.

[0025] A power supply 150 is coupled to the electrode. The power supply 150 provides a chucking voltage of about 200 volts to about 2000 volts to the electrode 132. The power supply 150 may also include a system controller (not shown) for controlling the operation of the electrode 132 by directing DC current to the electrode 132 for chucking and dechucking the substrate 138. A vertical tube 137 provides passage for power supplies, sensors, and other wiring used by the substrate support pedestal 140.

[0026] According to one example of the present invention, a hoop assembly 144 is disposed within the upper chamber volume 120. As previously mentioned, the hoop assembly 144 can be used in other processing chambers and / or load lock chambers. The hoop assembly 144 has at least two functions. First, the hoop assembly 144 can be positioned vertically to transfer substrates between the substrate support pedestal 140 and a substrate transfer device (e.g., a robot end effector) entering the upper chamber volume 120. Second, the hoop assembly 144 can be positioned to define a cylindrical containment region 144a around the substrate 138 and the area directly above the substrate support pedestal 140 during processing, thereby providing a symmetrical processing environment within the upper chamber volume 120, which enhances processing. The hoop assembly 144 can also be used alone to establish a symmetrical containment region within the processing volume.

[0027] The hoop assembly 144 includes a ring-shaped hoop body 146 disposed within the upper chamber volume 20. The hoop body 146 has an inner diameter that is larger than the diameter of the substrate support pedestal 140. The hoop body 146 is coupled to a shaft 157 that extends through the chamber body 103 to a lift actuator 158. The lift actuator 158, such as a linear actuator or an electric motor, is operable to control the vertical elevation of the hoop body 146 within the upper chamber volume 120. In one example, a bellows assembly 156 is provided to prevent leakage between the shaft 157 and the chamber body 103.

[0028] The hoop assembly 144 also includes three or more lifting fingers (not shown) attached to the hoop body 146. The lifting fingers are configured to transfer substrates between the substrate support pedestal 140 and a substrate transfer device, such as a robot, that deploys into the upper chamber volume 120 when the hoop assembly 144 is in the upper transfer position, as shown in FIG.

[0029] The hoop assembly 144 also includes a hoop 145 attached to a hoop body 146. The hoop 145 extends vertically upward from the hoop body 146. In one example, the hoop 145 is a cylindrical ring having a substantially cylindrical inner wall 145a. The height 145b of the inner wall 145a is much greater than the thickness of the substrate 138, such that the inner wall 145a can confine a portion of the processing volume around and above the substrate 138 as a cylindrical containment region 144a. The inner wall 145a of the hoop 145 has a diameter greater than the outer diameter of the substrate support pedestal 140. In one example, the hoop 145 is tall enough to simultaneously overlap the substrate support pedestal 140 during processing.

[0030] The gas panel 160 is coupled to the chamber lid assembly 116 by gas lines 167 and supplies process gases into the upper chamber volume 120. The gas panel 160 can include one or more process gas sources 161, 162, 163, and 164, and can additionally include inert, non-reactive, and reactive gases as needed. In one example, the gas panel 160 is configured to deliver a metal precursor, such as aluminum, hafnium, or zirconium. In one example, the gas panel is configured to deliver tri-methylaluminum (TMA). In another example, the gas panel 160 is configured to deliver gas and vapor-phase precursors, such as tetrakis(ethylmethylamido)zirconium(IV) (TEMAZr) and tetrakis(ethylmethylamido)hafnium(IV) (TEMAHf). The gas panel 160 can be adapted to include one or more vapor-phase precursor sources disposed within or coupled to the gas panel 160. The vapor-phase precursor source uses a thermal and / or vacuum-enhanced evaporation process to vaporize a liquid precursor provided from a liquid-phase precursor ampoule in fluid communication with the vapor-phase precursor source. In other examples, the vapor-phase precursor source is a liquid injection vaporizer configured to provide a mixture of vapor-phase precursor and a carrier gas to the upper chamber volume 120 of the processing chamber 100. In some examples, the vapor-phase precursor source is configured to evaporate or sublimate a solid precursor.

[0031] Additional examples of process gases that can be provided by the gas panel 160 include, but are not limited to, hydrocarbon-containing gases including methane (CH), sulfur hexafluoride (SF), silicon chloride (SiCl), or organosilicon-containing gases such as bis(diethylamido)silane (BDEAS), tris(dimethylamino)silane (TDMAS), bis(tertiary-butylamino)silane (BTBAS), carbon tetrafluoride (CF), hydrogen bromide (HBr), hydrocarbon-containing gases, argon gas (Ar), chlorine (Cl), nitrogen (N), helium (He), and oxygen gas (O). Additionally, the process gas may include nitrogen, chlorine, fluorine, oxygen, and hydrogen-containing gases such as BCl3, C2F4, C4F8, C4F6, C2F2, C2F6, C5F8, CHF3, CH2F2, CH3F, F2, NF3, NH3, CO2, SO2, CO, N2, NO2, N2O, and H2, among others.

[0032] Valves 166 control the flow of process gas from process gas sources 161, 162, 163, 164 from gas panel 160 and are managed by controller 180. The flow of gas supplied from gas panel 160 to upper chamber volume 120 can include one of the disclosed gases or a combination of those gases.

[0033] The chamber lid assembly 116 includes a nozzle 114 that is fluidly coupled to a gas line 167. The nozzle 114 has one or more ports for introducing process gases from process gas sources 161, 162, 164, 163 of a gas panel 160 into the upper chamber volume 120. As the process gases are introduced into the processing chamber 100, energy is provided to the gases to form a plasma. Alternatively, gases, i.e., precursors, can be provided to the upper chamber volume and pulsed under pressure for a predetermined period of time to cause the precursors to react with the substrate surface, for example, by ALD.

[0034] An antenna 148, such as one or more inductor coils, can be provided adjacent to the processing chamber 100. An antenna power supply 142 can supply power to the antenna 148 through a matching network 141 to inductively couple energy, such as RF energy, to the process gases, thereby maintaining a plasma formed from the process gases in the upper chamber volume 120 of the processing chamber 100. Alternatively, or in addition to the antenna power supply 142, process electrodes below and / or above the substrate 138 can be used to capacitively couple RF power to the process gases, thereby maintaining a plasma in the upper chamber volume 120. The operation of the antenna power supply 142 can be controlled by a controller, such as controller 180, which also controls the operation of other components in the processing chamber 100.

[0035] A controller 180 is coupled to the processing chamber 100 to control its operation. For example, the controller 180 is configured to control the flow of various precursor and process gases and purge gases from gas sources during substrate processing sequences of different operations. The controller 180 includes a processor 182, a memory 184, and support circuits 186 for the processor 182 to facilitate control of the components of the processing chamber 100. The controller 180 may be one of any form of general-purpose computer processor and sub-processors that can be used in industrial settings to control various chambers. The memory 184 stores software (source code or object code) that can be executed or effected to control the operation of the processing chamber 100 in the manner described herein. The memory 184 is a non-transitory computer-readable medium and may be one or more of random access memory (RAM), read-only memory (ROM), or any other form of readily available memory, such as digital storage, local or remote. The memory 184 includes instructions that, when executed by the processor 182, facilitate the performance of the method 200 (shown in FIG. 2).

[0036] To facilitate control of the processing chamber 100, the processor 182 may be one of any form of general-purpose computer processor or general-purpose central processing unit (CPU), each of which may be used in industrial settings such as programmable logic controllers (PLCs) for controlling various chambers and sub-processors. Support circuits 186 are coupled to the processor 182 and support the processor in a conventional manner. Charged species generation, heating, and other processes are typically stored in memory 184, typically as software routines. The software routines may also be stored and / or executed by a second CPU (not shown) located remotely from the processing chamber 100 controlled by the processor 182.

[0037] The memory 184 is a form of computer-readable storage medium containing instructions that, when executed by the processor 182, facilitate operation of the process chamber 100. The instructions in the memory 184 are in the form of a program product, such as a program, that implements the methods of the present disclosure. The program code can be in any one of many different programming languages. In one example, the present disclosure can be implemented as a program product stored on a computer-readable storage medium for use with a computer system. The program in the program product defines the functions of the examples (including the methods described herein). Example computer-readable storage media include, but are not limited to, (i) non-writable storage media on which information is permanently stored (e.g., a read-only memory device such as a CD-ROM disk readable by a CD-ROM drive in a computer, flash memory, a ROM chip, or any type of solid-state nonvolatile semiconductor memory), and (ii) writable storage media on which changeable information is stored (e.g., a floppy disk in a diskette drive or hard-disk drive, or any type of solid-state random-access semiconductor memory). Such computer-readable storage media, when carrying computer-readable instructions that direct the functions of the methods described herein, are examples of the present disclosure.

[0038] 2 illustrates a flow chart of a method 200 for patterning a film stack 300. In one example, the film stack 300 is patterned by a photolithography and etching process. FIGS. 3A-3F illustrate cross-sectional views of a portion of the film stack 300 at various stages of the method 200.

[0039] FIG. 3A illustrates a cross section of a film stack 300 including a substrate 138 having a bottom layer 301 disposed over and in contact with the substrate 138. The film stack 300 also includes a photoresist layer 302 disposed over and in contact with the bottom layer 301. The photoresist layer 302 includes one or more patterned layers 304. To better illustrate examples of the present disclosure, the patterned layers 304 are shown adjacent to each other with gaps between them. However, it is understood that examples of patterned layers 304 of the photoresist layer 302 could be disposed with portions of the photoresist layer 302 connected without departing from the present disclosure. Exemplary materials for the substrate 138 include silicon, silicon oxide, doped silicon, silicon germanium, germanium, gallium arsenide, glass, sapphire, and any other material, such as a metal, a metal nitride, a metal alloy, and other conductive or semiconductive materials, depending on the application. The substrate 138 or its surface may be made of a dielectric material such as silicon dioxide, silicon nitride, organosilicates, and carbon-doped silicon oxide or silicon nitride materials.

[0040] In one example, the lower layer 301 may be a sol-gel solution or a nanoparticle solution. The first solution may include silicon dioxide (SiO2) and / or silicon oxycarbide (SiOC). In the first solution, the ratio of SiO2 to SiOC is controlled to obtain a first refractive index. For example, the first solution may include a first ratio of SiO2 or SiOC. In one embodiment, the sol-gel precursor for SiO2 may include tetramethyl orthosilicate (TMOS), methyl-tri-methoxy-silane (MTMS), and tetraethyl orthosilicate (TEOS). The first refractive layer may include a first material, and subsequent refractive layers may include a second material different from the first material. A series of refractive layers, such as a graded antireflective coating (ARC), may include metals and / or dielectrics of various dielectric constants and refractive indices to reduce glare, reflection, or blur. The refractive index of the encapsulation layer may be adjusted from greater than about 2.0 to about 1.47. An exemplary range for the refractive index of bottom layer 301 may be between about 1.5 and about 2.0, such as about 1.75. In yet another example, the refractive index of bottom layer 301 may be between about 1.0 and about 1.5, such as about 1.47. In yet another example, the refractive index of bottom layer 301 may be between about 1.0 and about 1.5, such as about 1.48 or about 1.49, or between about 1.0 and about 1.5, such as about 1.47.

[0041] 2 and 3B, the method 200 begins at operation 202, in which a methyl-containing material 306 is provided to a processing volume of a processing chamber, such as the upper chamber volume 120 of the processing chamber 100 having the film stack 300 disposed therein. The methyl-containing material is provided to the processing volume (e.g., the upper chamber volume 120) at high pressure. In one example, the methyl-containing material 306 is a gas containing tri-methylaluminum (TMA). Alternatively, the methyl-containing material 306 can be provided as a vapor or liquid that can be provided to the processing volume. In one example, the vapor or liquid includes (TEMAZr) or (TEMAHf). The methyl-containing material 306 is provided to the upper chamber volume 120 at a predetermined temperature, pressure, and for a predetermined time. The methyl-containing material 306 includes aluminum atoms 308, hydrogen atoms 310, and carbon atoms 312. In one example, the methyl-containing material 306 is provided to the upper chamber volume 120 at high pressure for a predetermined time at a predetermined temperature. For example, the pressure may be from about 1 Torr to about 10 Torr, or from about 100 mTorr to about 10 Torr, such as between about 3 Torr and about 7 Torr. The predetermined time is between about 1 second and about 45 seconds, such as between about 10 seconds and 30 seconds. In another example, the pressurized methyl-containing material 306 is provided to the upper chamber volume 120 for about 15 seconds, or about 20 seconds, or about 30 seconds. In at least one example, the predetermined temperature is between about 0 degrees Celsius and about 150 degrees Celsius, such as between about 50 degrees Celsius and about 100 degrees Celsius, such as between about 75 degrees Celsius and about 100 degrees Celsius.

[0042] In operation 204, the methyl-containing material is absorbed into the patterned photoresist layer. Providing heat, for example, in the upper chamber volume 120, can cause the methyl-containing material 306 to diffuse into the patterned layer 304 of the photoresist layer 302, as shown in FIG. 3C . This heat can also create gaps or spaces between the polymers 314, which can be infiltrated by the methyl-containing material 306 when pressure is applied. For clarity, FIG. 3C shows only one patterned layer 304 in the film stack 300. The polymers 314 in the photoresist layer 302 are sufficiently dispersed to allow the methyl-containing material 306 to diffuse through the top surface 316 of the photoresist layer 302, so that the methyl-containing material 306 can occupy the spaces between the polymers 314. The photoresist layer 302 is saturated with the methyl-containing material 306. The methyl-containing material 306 is therefore trapped between the top surface 316 and the bottom surface 318 of the photoresist layer 302. In other words, the methyl-containing material 306 is absorbed and uniformly distributed throughout the thickness of the photoresist layer 302, which is defined as the distance between the top surface 316 and the bottom surface 318.

[0043] In operation 206, the process volume is purged of methyl-containing material. For example, a purge gas is introduced into the upper chamber volume 120 for approximately 20 seconds. After approximately 20 seconds, the flow of the purge gas is stopped, and the purge gas, along with any remaining methyl-containing material 306, is evacuated from the upper chamber volume 120 for approximately 20 seconds using one or more dedicated vacuum pumps. The one or more dedicated vacuum pumps (not shown) are part of a vacuum pumping system (not shown), in one example. The purge gas is a non-reactive gas, and in one example, may be N. In another example, the purge gas is a chemically inert gas such as Ar or He. Purging can leave the top surface 316 of the photoresist layer 302 substantially free of methyl-containing material 306 in preparation for oxidation in operation 208.

[0044] 3D-3E illustrate the oxidation of the film stack described in operation 208. An oxidizing agent 320 containing oxygen atoms 322 and hydrogen atoms 310 is introduced into the upper chamber volume 120. In one example, the oxidizing agent 320 is water, which can be provided to the upper chamber volume 120 as a liquid or gas, as shown in FIG. 3D. When the methyl-containing material 306 interacts with the oxidizing agent 320 during the oxidation process 326, a metal oxide 324 and a byproduct gas 328 are formed within the photoresist layer 302. The byproduct gas 328 diffuses from the photoresist layer 302 through the surface of the patterned layer 304, including the top surface 316. Because the top surface 316 of the photoresist layer 302 is in contact with the upper chamber volume 120 and the material contained in the lower layer 301 is denser than any gas in the upper chamber volume 120, there is substantially no diffusion of the byproduct gas 328 through the lower layer 301.

[0045] When the methyl group-containing material 306 is TMA, alumina (AlO x ) is the metal oxide 324 produced, and the by-product gas 328 is methane. xmay be Al2O3, Al2O, AlO2, or AlO. Alternatively, if the methyl-containing material 306 is TEMAZr, the metal oxide 324 formed in the photoresist layer 302 upon oxidation is ZrOx, such as ZrO2 or ZrO. If the methyl-containing material 306 is TEMAHf, oxidizing the methyl-containing material 306 produces HfOx, such as HfO2, in the photoresist layer 302. The concentration of the metal oxide 324 is between about 30 percent and about 60 percent by volume of the photoresist layer 302. TEMAZr and TEMAHf infiltrate the photoresist layer 302, but do not infiltrate the entire thickness of the photoresist layer 302 as compared to TMA. The TEMAZr and TEMAHf penetrate closer to the top surface 316 of the photoresist layer 302 to form a crust-like layer having TEMAZr and / or TEMAHf with polymer 314 near the top surface 316, and a layer of polymer 314 near the bottom surface 316. For example, the TEMAZr and TEMAHf may penetrate into the photoresist layer 302 to a depth of about 0.05 nm to about 2 nm, such as about 1 nm or about 1.5 nm. Thus, the polymer 314 is formed throughout the remaining thickness of the photoresist layer 302. Advantageously, in the case of ZrOx or HfOx, AlO x , resulting in higher selectivity during subsequent etching of the film stack 300.

[0046] The photoresist layer 302 is exposed to an oxidizing agent at a predetermined pressure, temperature, and for a predetermined time. The oxidizing agent 320 is provided to the processing volume of the processing chamber under high pressure. For example, the oxidizing agent 320 can be provided to the upper chamber volume 120 (i.e., processing volume) at a pressure between about 100 mTorr and about 10 Torr, such as between about 1 Torr and about 10 Torr, or between about 3 Torr and about 7 Torr. The temperature at which the oxidizing agent 320 is provided to the processing volume is between about 50 degrees Celsius and about 100 degrees Celsius, such as between about 75 degrees Celsius and about 100 degrees Celsius.

[0047] In one example, the predetermined time for which the oxidizing agent 320 is provided to the upper chamber volume 120 is between about 1 second and about 400 seconds. During the predetermined time, the methyl-containing materials in the photoresist layer are oxidized by a hydrolysis reaction. In another example, the predetermined time is between about 240 seconds and about 350 seconds, such as about 270 seconds, about 300 seconds, or about 330 seconds. This predetermined time ensures that the oxidation process 326 can occur throughout the photoresist layer 302 and form a metal oxide 324 uniformly distributed between the top surface 316 and the bottom surface 318. If the photoresist layer 302 is exposed to the oxidizing source for less than the predetermined time, a layer of alumina will form near the top surface 316 of the photoresist layer 302 without forming throughout the photoresist layer 302, resulting in a layer of polymer 314 near the bottom surface 318. If the photoresist layer 302 is exposed to an oxidizing source, such as the oxidizing agent 320, for less than a predetermined time, the metal oxide 324 may concentrate on the top surface 316 of the mask, resulting in a crust, even though the methyl-containing material 306 has spread throughout the thickness of the photoresist layer 302.

[0048] 3E, the metal oxide 324 formed in operation 208 includes metal atoms 332 and oxygen atoms 322. In one example, when the methyl group-containing material 306 is TMA, the metal atoms 332 are aluminum, and therefore the metal oxide 324 is alumina (AlO x Alternatively, if the methyl group-containing material 306 is TEMAZr, the metal atoms 332 are zirconium, and the metal oxide 324 formed is zirconium oxide (ZrO x As yet another example, when TEMAHf is the methyl-containing material 306, the metal oxide 324 formed is hafnium oxide (HfO x ) and metal atom 332 is hafnium.

[0049] In operation 210, the film stack with the patterned treated photoresist layer is etched. The film stack 300 is exposed to an etchant 330, which may be, for example, a dry etch or a wet etch. In one example, the film stack 300 is etched using a fluorine-containing gas or Carbon-Fluorine The film stack 300 is exposed to an etchant 330 from a plasma formed from any of the process gases discussed above, such as a methyl-containing gas. When exposed to the plasma and subjected to an electric field generated by an RF generator or DC power source, as detailed above, the process gas dissociates, generating components from the process gas, including ions, neutrons, protons, and radicals. Advantageously, the metal oxide 324 formed in operation 208 improves etch selectivity in operation 210. Optionally, in operation 212, the method 200 can return to operation 202, where another photoresist layer 302 is deposited and the film stack 300 is again exposed to a methyl-containing material 306.

[0050] Examples of the present disclosure relate to methods for forming metal oxides in photoresists to improve profile control. Advantageously, the methods disclosed herein can achieve critical dimensions (CD) of less than 1 nm and line width roughness (LWR) of less than 0.4 nm. As used herein, the term "about" refers to a + / - 10% variation from the nominal value. It is understood that such variations may be included in all values ​​provided herein. The foregoing is intended to illustrate examples of the present disclosure; however, other and further examples of the present disclosure may be devised without departing from the basic scope of the present disclosure, which is determined by the following claims.

Claims

1. 1. A method for infiltrating a photoresist layer, comprising: heating a methyl-group-containing material in a processing environment proximate a film stack, the film stack comprising a patterned photoresist layer having a thickness between 20 nm and 40 nm, the patterned photoresist layer being disposed on and in contact with an underlayer comprising a sol-gel solution or a nanoparticle solution having a refractive index between 1.47 and 2.0, the methyl-group-containing material interacting with an oxidizing agent within the patterned photoresist layer proximate a top surface of the patterned photoresist layer to produce a metal oxide and by-product gases, the by-product gases diffusing from the photoresist layer but not through the underlayer; Etching the film stack including the patterned photoresist layer implanted with the metal oxide; A method comprising:

2. Absorbing the methyl group-containing material through the top surface of the patterned photoresist layer. The method of claim 1 further comprising:

3. 3. The method of claim 2, wherein the methyl-containing material is absorbed throughout the thickness of the patterned photoresist layer and the metal oxide is alumina.

4. maintaining the patterned photoresist layer at a constant pressure to allow the methyl group-containing material to be absorbed throughout the thickness of the patterned photoresist layer; The method of claim 1 further comprising:

5. 5. The method of claim 4, wherein the methyl group-containing material is exposed to a temperature of 0 to 150 degrees Celsius for a time between 1 and 45 seconds.

6. purging the processing environment of the methyl group-containing material prior to oxidizing the methyl group-containing material. The method of claim 1 further comprising:

7. maintaining the hydrolysis reaction for a predetermined time between 1 second and 400 seconds to oxidize the methyl group-containing material in the patterned photoresist layer; The method of claim 6 further comprising:

8. Converting substantially all of said methyl group-containing material to alumina. The method of claim 1 further comprising:

9. The method of claim 8, wherein the film stack is etched using a fluorine-containing gas or a carbon-fluorine-containing gas.

10. 1. A method for infiltrating a photoresist layer, comprising: pressurizing a methyl-group-containing material in a processing environment proximate a film stack, the film stack comprising a patterned photoresist layer having a thickness between 20 nm and 40 nm, the patterned photoresist layer being disposed on and in contact with an underlying layer comprising a sol-gel solution or a nanoparticle solution having a refractive index between 1.47 and 2.0, the methyl-group-containing material interacting with an oxidizing agent in the patterned photoresist layer proximate a top surface of the patterned photoresist layer to produce a metal oxide and a by-product gas, the by-product gas diffusing from the photoresist layer but not through the underlying layer; heating the methyl group-containing material to a predetermined temperature; converting the methyl-group-containing material into a metal oxide in the patterned photoresist layer; Etching the film stack including the patterned photoresist layer implanted with the metal oxide; A method comprising:

11. maintaining the patterned photoresist layer at a constant pressure to allow the methyl group-containing material to be absorbed throughout the thickness of the patterned photoresist layer, wherein the metal oxide is alumina; The method of claim 10 further comprising:

12. 12. The method of claim 11, wherein the methyl group-containing material is exposed to a temperature of 0 to 150 degrees Celsius for a time between 1 and 45 seconds.

13. purging the processing environment of the methyl group-containing material prior to oxidizing the methyl group-containing material. The method of claim 10 further comprising:

14. oxidizing the methyl group-containing material in the patterned photoresist layer for a predetermined time between 1 second and 400 seconds; 14. The method of claim 13, further comprising:

15. oxidizing the methyl group-containing material in the patterned photoresist layer; converting substantially all of the methyl-containing material to alumina, wherein the film stack is etched using a fluorine-containing gas or a carbon-fluorine-containing gas; The method of claim 10 further comprising:

16. 1. A semiconductor processing system comprising: a semiconductor processing chamber; a non-transitory computer-readable medium storing instructions that, when executed by a processor, result in a method being performed within the semiconductor processing chamber; and wherein the method comprises: selectively infiltrating a metal oxide into a patterned photoresist layer by pressing a methyl-group containing material in a processing environment proximate a film stack, the film stack comprising the patterned photoresist layer having a thickness between 20 nm and 40 nm, the patterned photoresist layer being disposed on and in contact with an underlying layer comprising a sol-gel solution or a nanoparticle solution having a refractive index between 1.47 and 2.0, the methyl-group containing material interacting with an oxidizing agent in the patterned photoresist layer near a top surface of the patterned photoresist layer to produce a metal oxide and a by-product gas, the by-product gas diffusing out of the photoresist layer but not through the underlying layer; Etching the film stack including the patterned photoresist layer implanted with the metal oxide; 1. A semiconductor processing system comprising:

17. The method comprises: converting substantially all of said methyl group-containing material to alumina.

17. The semiconductor processing system of claim 16, further comprising:

18. The method comprises: heating the patterned photoresist layer at a constant pressure to allow the methyl group-containing material to be absorbed throughout the thickness of the patterned photoresist layer, wherein the metal oxide is alumina; 17. The semiconductor processing system of claim 16, further comprising:

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