Dose reduction for patterned metal oxide photoresists

Abstract

Various embodiments of the present disclosure generally relate to multilayer stacks for use as masks in extreme ultraviolet (EUV) lithography and methods for forming the multilayer stacks. In one embodiment, the method includes the steps of forming a carbon layer on top of the film stack, forming a metal-rich oxide layer on the carbon layer by a physical vapor deposition (PVD) process, forming a metal oxide photoresist layer on the metal-rich oxide layer, and patterning the metal oxide photoresist layer. The metal oxide photoresist layer is different from the metal-rich oxide layer and is formed by a process different from the PVD process. The metal-rich oxide layer formed by the PVD process improves the adhesion of the metal oxide photoresist layer and increases secondary electrons during EUV lithography, thereby resulting in a reduction in EUV dose energy.

Description

[0001] background

[0002] field

[0003] Various embodiments of the present disclosure relate generally to an apparatus and method, and more particularly, to a multilayer stack and a method for forming the multilayer stack.

[0004] Related technical description

[0005] Reliably producing submicron and smaller features is a key requirement for very large-scale integration (VLSI) and ultra-large-scale integration (ULSI) of semiconductor components. However, as circuit technology continues to miniaturize, the size and pitch of circuit features, such as interconnects, are increasing, placing additional demands on processing capabilities. At the heart of this technology are multilevel interconnects, which require precise imaging and placement of high-aspect-ratio features. These interconnects need to be reliably formed to further increase device and interconnect density.

[0006] One process for forming various interconnects and other semiconductor feature structures is to use extreme ultraviolet (EUV) lithography. Traditional EUV patterning uses a multilayer stack in which a photoresist is patterned on top of a hard mask. Common hard mask materials are spin-on silicon anti-reflective coating (SiARC) and deposited silicon oxynitride (SiON). SiARC incorporates organic components into the silicon backbone while maintaining sufficient etch selectivity to the photoresist and the stack below. Scaling the thickness of the SiARC backbone can be challenging, and spin coating limits the minimum thickness that can be achieved without too many defects. The SiON hard mask uses an organic adhesion layer (OAL) to improve the adhesion of the resist. The OAL prevents nitrogen poisoning and can be reworked.

[0007] Several metal oxide materials have been tested as EUV hard masks (HMs). Metal oxide films, including films with highly EUV absorbing elements, are stoichiometric and non-conductive. In addition, EUV lithography processes generally take considerable exposure time and require a large amount of energy.

[0008] Therefore, there is a need in the art for new multilayer stacks as masks that allow for reduced dose time and / or lower dose energy. Summary of the Invention

[0009] Various embodiments of the present disclosure generally relate to multilayer stacks for use as masks in extreme ultraviolet (EUV) lithography and methods for forming the multilayer stacks.

[0010] In one embodiment, a method for forming a multilayer stack is provided. The method includes the steps of forming a first layer on a film stack, forming a second layer on the first layer by a physical vapor deposition process, and forming a metal oxide photoresist layer on the second layer, wherein the first layer comprises a carbon-containing layer, the second layer comprises a metal oxide-rich layer, and the metal oxide photoresist layer comprises a different material than the second layer.

[0011] In another embodiment, a multilayer stack is provided. The multilayer stack includes a first layer disposed on a film stack, a second layer disposed on the first layer, and a metal oxide photoresist layer disposed on the second layer, wherein the first layer comprises a carbon-containing layer, the second layer comprises a metal oxide-rich layer, and the metal oxide photoresist layer comprises a different material than the second layer.

[0012] In yet another embodiment, a non-transitory computer-readable storage medium is provided. The non-transitory computer-readable storage medium includes a plurality of instructions, including instructions for controlling components of a processing system to perform the following process: forming a first layer on a film stack, forming a second layer on the first layer by a physical vapor deposition process, and forming a photoresist layer on the second layer, wherein the first layer includes a carbon-containing layer, the second layer includes a metal oxide-rich layer, and the photoresist layer includes a polymer having a metal oxide coating. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] In order to understand in detail how the above-described features of the present disclosure are structured, a more particular description of the present disclosure, briefly summarized above, may be obtained by reference to a number of embodiments, some of which are illustrated in the accompanying drawings. However, it should be noted that the accompanying drawings illustrate only a number of exemplary embodiments and are not to be construed as limiting the scope of the present disclosure, which may admit to many other equally effective embodiments.

[0014] Figure 1 is a flow chart of a method for a patterning process according to one embodiment.

[0015] Figure 2 A structure is shown according to one embodiment.

[0016] Figure 3 A schematic top view of a multi-chamber processing system is depicted according to one embodiment.

[0017] To facilitate understanding, identical reference numerals have been used, where possible, to designate identical elements in the drawings. It is contemplated that elements and features of one embodiment may be beneficially utilized in other embodiments without further recitation. DETAILED DESCRIPTION

[0018] Various embodiments of the present disclosure generally relate to multilayer stacks for use as masks in EUV lithography and methods for forming the multilayer stacks. In one embodiment, the method includes the steps of forming a carbon layer on the film stack, forming a metal-rich oxide layer on the carbon layer by a physical vapor deposition (PVD) process, forming a metal oxide photoresist layer on the metal-rich oxide layer, and patterning the metal oxide photoresist layer. The metal oxide photoresist layer is different from the metal-rich oxide layer and is formed by a process different from the PVD process. The metal-rich oxide layer formed by the PVD process improves the adhesion of the metal oxide photoresist layer and increases secondary electrons during EUV lithography, thereby resulting in a reduction in EUV dose energy.

[0019] Figure 1 is a flow chart of a method 100 for a patterning process according to one embodiment. Figure 2 The structure 200 is shown according to one embodiment. Figure 1 During the patterning process, structure 200 is formed. Those skilled in the art will recognize that the complete process for forming semiconductor devices and related structures is not depicted in the drawings or described herein. Although various operations are depicted in the drawings and described herein, no limitation is implied as to the order of these operations or the presence or absence of these operations. Unless explicitly stated, operations depicted or described sequentially are for illustrative purposes only and do not preclude the possibility that these various operations may be performed, at least partially, if not entirely, in parallel or in an overlapping manner.

[0020] The method 100 begins at operation 102 by forming a first layer 204 on a film stack 202 in a processing chamber of a processing system. The film stack 202 can be used to form a gate structure, a contact structure, or an interconnect structure in front-end or back-end processing. The film stack 202 can include a stair-like structure used in memory structures such as NOT-AND (NAND) structures.

[0021] In one embodiment, the film stack 202 has a plurality of vertically stacked layers. The film stack 202 may include pairs of alternating layers, such as alternating dielectric layers, for example, alternating oxide and nitride layers. The alternating dielectric layers may include silicon oxide, silicon nitride, silicon oxynitride, silicon carbide, silicon oxycarbide, titanium nitride, any other composite material of oxides and nitrides, or any combination of the above materials. In some embodiments, the dielectric layer includes one or more high-k materials having a dielectric constant greater than 4. Suitable examples of high-k materials include hafnium dioxide (HfO2), zirconium dioxide (ZrO2), hafnium silicon oxide (HfSiO2), hafnium aluminum oxide (HfAlO), zirconium silicon oxide (ZrSiO2), tantalum dioxide (TaO2), aluminum oxide, aluminum-doped hafnium dioxide, barium strontium titanate (BST), and lead zirconium titanate (PZT), or any combination thereof.

[0022] The first layer 204 may be a carbon-containing layer, such as a high-density carbon-containing layer. In one embodiment, the first layer 204 is a hard mask made of doped carbon (such as boron-doped amorphous carbon). The first layer 204 may be a Saphira® hard mask manufactured by Applied Materials, Inc., located in Santa Clara, California. TM Hardmask. In one embodiment, the first layer 204 includes one or more Advanced Patterning Film (APF) carbon hardmasks produced by Applied Materials, Inc., located in Santa Clara, California.

[0023] In some embodiments, the first layer 204 is a high-density carbon-containing layer with excellent film qualities, such as improved hardness and density. Such hardness and density allow the first layer 204 to serve as a stronger barrier against metal penetration and to reduce nanofailure to a greater extent than traditional SOC films.

[0024] In some embodiments, the first layer 204 has one or more of the following characteristics:

[0025] 1) sp 3 The number / percentage of hybridized carbon atoms (i.e. sp 3 The hybridized carbon atom content) is at least about 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80% or 85% of the total carbon atoms in the as-deposited layer, such as about 50% to about 90% or about 60% to about 70%.

[0026] 2) Thickness is about With Between, such as from about to about or about to about between, or about to about

[0027] 3) A refractive index at about 633 nm greater than about 2.0, for example, about 2.0 to about 3.0, such as about 2.3.

[0028] 4) An extinction coefficient at about 633 nm greater than about 0.1, for example, from about 0.2 to about 0.3, such as about 0.25.

[0029] 5) Stress is less than about -300 MPa, such as about -600 MPa to about -300 MPa, or about -600 MPa to about -500 MPa, such as about -550 MPa.

[0030] 6) Density greater than about 1.8 g / cc, such as about 2.0 g / cc or greater, or about 2.5 g / cc or greater, such as about 1.8 g / cc to about 2.5 g / cc.

[0031] 7) An elastic modulus greater than about 150 GPa, such as about 200 GPa to about 400 GPa.

[0032] The first layer 204 can be formed on the film stack 202 by a physical vapor deposition (PVD) process or a plasma enhanced chemical vapor deposition (PECVD) process. In one embodiment, the first layer 204 is a diamond-like carbon layer. The diamond-like carbon layer described herein can be formed by a chemical vapor deposition (CVD) (plasma enhanced and / or thermal) process using a hydrocarbon-containing gas mixture. The hydrocarbon-containing gas mixture can include precursors including, but not limited to, acetylene, propylene, methane, butene, 1,3-dimethyladamantane, bicyclo[2.2.1]hepta-2,5-diene (2,5-norbornadiene), adamantane, norbornene, or combinations thereof.

[0033] The deposition process may be performed at a temperature ranging from about -50°C to about 600°C. The deposition process may be performed at a pressure of about 0.1 mTorr to about 10 Torr in the process space. The hydrocarbon-containing gas mixture may further include any one of helium, argon, xenon, nitrogen (N2), and hydrogen (H2), or a combination thereof.

[0034] The hydrocarbon-containing gas mixture may further include an etchant gas (e.g., chlorine), carbon tetrafluoride, and / or nitrogen trifluoride to improve film quality. A plasma (e.g., a capacitively coupled plasma) may be formed from one of the top and bottom electrodes or the side electrodes. The electrodes may be formed from a single powered electrode, dual powered electrodes, or more electrodes having multiple frequencies (e.g., but not limited to, about 350 KHz to about 100 MHz) that may be used alternatively or simultaneously in a CVD system with any or all of the reactive gases listed in this specification to deposit a thin layer of diamond-like carbon for use as a hard mask and / or etch stop or any other suitable application.

[0035] The high etch selectivity of the diamond-like carbon layer is achieved by having a higher density and modulus than the current generating film. Without being bound by theory, it is generally believed that the higher density and modulus are due to the sp 3 The content of hybridized carbon atoms is high, which can be achieved through a combination of low pressure and plasma power.

[0036] In some embodiments, hydrogen radicals are fed by a remote plasma source (RPS), which results in the generation of sp 2 Selective etching of hybridized carbon atoms. Therefore, the sp 3 The hybridized carbon atom fraction is further increased, thereby further increasing the etching selectivity.

[0037] In one embodiment, the diamond-like carbon layer is deposited in a chamber wherein the substrate pedestal is maintained at about 10° C. and a pressure of about 2 mTorr, wherein a plasma is generated at substrate level by biasing an electrostatic chuck at about 2500 W at a frequency of about 13.56 MHz. In some embodiments, an additional radio frequency (RF) of about 1000 W at about 2 MHz is also delivered to the electrostatic chuck, thereby generating a dual-bias plasma at substrate level.

[0038] In operation 104, a second layer 206 is formed on the first layer 204. The second layer 206 is a metal oxide layer formed by a PVD process. The metal oxide layer can be a rich metal oxide layer that provides sufficient secondary electrons when excited by EUV radiation. A completely stoichiometric metal oxide layer does not produce as many electrons as a rich metal oxide layer. Consider including a high Z metal and a low resistance rich metal oxide layer for EUV process to reduce EUV dose energy. High Z metal refers to a metal with an atomic number greater than or equal to 40. In some embodiments, the second layer 206 is a rich metal oxide layer that includes one or more of tin (Sn), indium (In), gallium (Ga), zinc (Zn), tellurium (Te), antimony (Sb), nickel (Ni), titanium (Ti), aluminum (Al), or tantalum (Ta). Examples of rich metal oxide layers include tin oxide (SnO x ), indium gallium zinc oxide (IGZO), indium tin oxide (ITO), tantalum oxide (TaO x ) or other suitable rich metal oxides. The metal-rich oxide layer is formed by a PVD process, which can produce a metal oxide layer with a nonstoichiometric ratio of metal to oxide, such as a higher metal content. For example, a stoichiometric metal oxide layer can be characterized as M x O y , wherein M is one or more metals, and the stoichiometric metal-to-oxide ratio is x to y. The metal-rich oxide layer produced by the PVD process can have a metal-to-oxide ratio of about 1.5x to y (1.5x-to-y) or greater, such as about 2x to y (2x-to-y) or greater.

[0039] At operation 106, a metal oxide photoresist layer 208 is formed on the second layer 206. The metal oxide photoresist layer 208 may include molecular metal oxide cluster cores, each core having a plurality of radiation-sensitive ligands. The metal oxide photoresist layer 208 is made of a different material than the second layer 206. The second layer 206 improves the adhesion of the metal oxide photoresist layer 208 to the second layer 206.

[0040] At operation 108, the metal oxide photoresist layer 208 is patterned to form a pattern 210 in the metal oxide photoresist layer 208. The metal oxide photoresist layer 208 can be a positive resist that becomes soluble when exposed to radiation, or a negative resist that becomes insoluble when exposed to radiation. The radiation can have a wavelength in the EUV range.

[0041] At operation 110, the pattern 210 is transferred to the film stack 202 by one or more etching processes. The pattern 210 is first transferred to the first layer 204 and the second layer 206, and then to the film stack 202. The one or more etching processes may include any suitable etching process.

[0042] The first layer 204 may be a doped carbon layer or a high-density carbon-containing layer, and the second layer 206 may be a metal-rich oxide layer formed by a PVD process. In one embodiment, the first layer 204 is a doped carbon layer, such as a boron-doped carbon layer, and the second layer 206 is a metal-rich oxide layer. In another embodiment, the first layer 204 is a high-density carbon-containing layer, such as a diamond-like carbon layer having a density greater than about 1.8 g / cc.

[0043] Figure 3 A schematic top view of a multi-chamber processing system 300 is depicted according to one embodiment. The multi-chamber processing system 300 can be configured to perform the method 100. Examples of processing systems that can be appropriately modified according to the teachings provided herein include the ® ... or It is contemplated that other processing systems (including those from other manufacturers) may be adapted to benefit from various aspects described herein.

[0044] like Figure 3 As shown, a plurality of process chambers 302 are coupled to a first transfer chamber 304. The first transfer chamber 304 is also coupled to a first pair of pass-through chambers 306. The first transfer chamber 304 has a centrally located transfer robot (not shown) for transferring substrates between the pass-through chambers 306 and the process chambers 302. The pass-through chambers 306 are coupled to a second transfer chamber 310, which is coupled to a process chamber 314 and a process chamber 316. The second transfer chamber 310 has a centrally located transfer robot (not shown) for transferring substrates between a set of load lock chambers 312 and either the process chamber 314 or the process chamber 316. A factory interface 320 is connected to the second transfer chamber 310 through the load lock chambers 312. The factory interface 320 is coupled to one or more pods 330 on opposite sides of the load lock chambers 312. The bay 330 is typically a front opening unit (FOUP) accessible from a cleaning room.

[0045] During operation, the substrate is first transferred to the processing chamber 314 or the processing chamber 316, wherein the film stack (eg Figure 2In other words, operation 102 of method 100 may be performed in processing chamber 314 or 316.

[0046] The substrate is then transferred to one or more processing chambers 302, where a metal-rich oxide layer (e.g., second layer 206) is formed on the carbon-containing layer by a PVD process. In other words, operation 104 of method 100 can be performed in a processing chamber 302. Processing chamber 302 can be a PVD chamber. Because operations 102 and 104 are performed within the same processing system 300, vacuum is not broken when the substrate is transferred to various chambers, which reduces the chance of contamination and improves the quality of the deposited epitaxial film.

[0047] In some embodiments, the substrate is provided to a chamber of a processing system different from the processing system 300 to form a photoresist layer (operation 106). Patterning of the photoresist layer (operation 108) and transferring the pattern to the film stack (operation 110) can be performed in a chamber of a processing system different from the processing system 300. In other words, operations 102 and 104 can be performed in a first processing system, and operations 106, 108, and 110 can be performed in a second processing system different from the first processing system.

[0048] The system controller 380 is coupled to the processing system 300 to control the processing system 300 or components of the processing system 300. For example, the system controller 380 controls the operation of the processing system 300 using direct control of the chambers 302, 304, 306, 310, 312, 314, 316, the factory interface 320, and / or the pods 330 of the processing system 300. In another example, the system controller 380 controls individual controllers associated with the chambers 302, 304, 306, 310, 312, 314, 316, the factory interface 320, and / or the pods 330 of the processing system 300. In operation, the system controller 380 enables data and feedback to be collected from the various chambers to coordinate the performance of the processing system 300.

[0049] System controller 380 typically includes a central processing unit (CPU) 382, ​​memory 384, and support circuits 386. CPU 382 can be any general-purpose processor suitable for use in an industrial environment. Memory 384, a non-transitory computer-readable medium or machine-readable storage device, is accessible by CPU 382 and can include random access memory (RAM), read-only memory (ROM), a floppy or hard disk, or any other form of digital storage (whether local or remote). Support circuits 386 are coupled to CPU 832 and include cache, clock circuits, input / output subsystems, power supplies, and similar circuits.

[0050] System controller 380 is configured to perform one or more operations of method 100 stored in memory 384. Generally, various embodiments disclosed herein are performed by executing computer instruction program code (e.g., a computer program product or software routine) stored in memory 384 (or in memory of a particular processing chamber) under the control of CPU 382. That is, the computer program product is tangibly embodied in memory 384 (or on a non-transitory computer-readable medium or machine-readable storage device). When the computer instruction program code is executed by CPU 382, ​​CPU 382 controls the chamber to perform operations according to various embodiments.

[0051] As described above, various embodiments of the present disclosure reduce EUV dose energy by utilizing a metal oxide-rich layer and a metal oxide photoresist formed on the metal oxide-rich layer. The adhesion of the metal oxide photoresist to the metal oxide-rich layer is also improved. Furthermore, various embodiments of the present disclosure utilize a high-density carbon-containing layer, which acts as a strong barrier against metal penetration and reduces nano-faults during EUV processing.

[0052] While the foregoing is directed to various embodiments of the present disclosure, various other and further embodiments of the disclosure may be devised without departing from the true scope of the disclosure, the scope of which is defined by the following claims.

Claims

1. A method for forming a multilayer stack, comprising the steps of: forming a first layer on the membrane stack, the first layer comprising a carbon-containing layer; forming a second layer on the first layer by a physical vapor deposition process, the second layer comprising a metal-rich oxide layer, wherein the metal-rich oxide layer has a metal-to-oxide ratio of 1.5 times or more the stoichiometric metal-to-oxide ratio; and forming a metal oxide photoresist layer on the second layer, the metal oxide photoresist layer comprising a material different from that of the second layer, wherein the second layer improves the adhesion of the metal oxide photoresist layer to the second layer, The metal oxide photoresist layer includes molecular metal oxide cluster cores, each core having a plurality of radiation sensitive ligands. The method of claim 1 , wherein the first layer further comprises a doped carbon-containing layer. The method of claim 2 , wherein the first layer further comprises a boron-doped carbon layer.

4. The method of claim 1, wherein the first layer further comprises a carbonaceous layer having a density greater than 1.8 g / cc. The method of claim 4 , wherein the carbon-containing layer is a diamond-like carbon layer. The method of claim 1 , wherein the second layer further comprises a high-Z metal.

7. The method of claim 1, wherein the second layer further comprises one or more of: tin, indium, gallium, zinc, tellurium, antimony, nickel, titanium, aluminum, or tantalum. 8 . The method of claim 7 , wherein the second layer is a tin oxide layer, an indium gallium zinc oxide layer, an indium tin oxide layer, or a tantalum oxide layer.

9. A multilayer stack for use as a mask in extreme ultraviolet lithography, comprising: a first layer disposed on the membrane stack, the first layer comprising a carbon-containing layer; a second layer disposed on the first layer, the second layer comprising a metal-rich oxide layer, wherein the metal-rich oxide layer has a metal-to-oxide ratio of 1.5 times or greater than the stoichiometric metal-to-oxide ratio; and a metal oxide photoresist layer disposed on the second layer, the metal oxide photoresist layer comprising a material different from that of the second layer, wherein the second layer improves the adhesion of the metal oxide photoresist layer to the second layer, The metal oxide photoresist layer includes molecular metal oxide cluster cores, each core having a plurality of radiation sensitive ligands.

10. The multilayer stack of claim 9, wherein the first layer further comprises a doped carbon-containing layer. The multilayer stack of claim 10 , wherein the first layer further comprises a boron-doped carbon layer.

12. The multi-layer stack of claim 9, wherein the first layer further comprises a carbon-containing layer having a density greater than 1.8 g / cc.

13. The multilayer stack of claim 12, wherein the carbon-containing layer is a diamond-like carbon layer.

14. The multilayer stack of claim 9, wherein the second layer further comprises a high-Z metal.

15. The multilayer stack of claim 9, wherein the second layer further comprises one or more of: tin, indium, gallium, zinc, tellurium, antimony, nickel, titanium, aluminum, or tantalum. 16 . The multilayer stack of claim 15 , wherein the second layer is a tin oxide layer, an indium gallium zinc oxide layer, an indium tin oxide layer, or a tantalum oxide layer. 17 . The multilayer stack of claim 12 , wherein the second layer is a tin oxide layer, an indium gallium zinc oxide layer, an indium tin oxide layer, or a tantalum oxide layer.

18. A non-transitory computer-readable storage medium having a plurality of instructions stored thereon, the plurality of instructions comprising a plurality of instructions for controlling components of a processing system to: forming a first layer on the membrane stack, the first layer comprising a carbon-containing layer, the carbon-containing layer having a density greater than 1.8 g / cc; forming a second layer on the first layer by a physical vapor deposition process, the second layer comprising a metal-rich oxide layer, the second layer comprising one or more of: tin, indium, gallium, zinc, tellurium, antimony, nickel, titanium, aluminum, or tantalum; and forming a metal oxide photoresist layer on the second layer, the metal oxide photoresist layer comprising a material different from that of the second layer, wherein the second layer improves adhesion of the metal oxide photoresist layer to the second layer, and wherein the metal oxide photoresist layer comprises molecular metal oxide cluster cores, each core having a plurality of radiation sensitive ligands.

19. The non-transitory computer-readable storage medium of claim 18, wherein the first layer is a diamond-like carbon layer. 20 . The non-transitory computer-readable storage medium of claim 18 , wherein the second layer is a tin oxide layer, an indium gallium zinc oxide layer, an indium tin oxide layer, or a tantalum oxide layer.

Images