Photoresist, method for manufacturing semiconductor device, and extreme ultraviolet lithography method

Abstract

A photoresist, a method for manufacturing a semiconductor device, and an extreme ultraviolet lithography method are disclosed. The method for manufacturing a semiconductor device includes the following steps: forming a photoresist layer on a substrate, selectively exposing the photoresist layer to EUV radiation, and developing the selectively exposed photoresist layer. The photoresist layer is composed of a solvent and a photosensitive compound, which is dissolved in the solvent and consists of a molecular cluster compound that binds hexameric tin and two chlorine ligands.

Description

Technical Field

[0001] The present disclosure relates to a photoresist, a method for manufacturing a semiconductor device, and an extreme ultraviolet lithography method. Background Art

[0002] As the size of modern integrated circuits decreases, the size of the associated features also decreases. Photolithography is a mechanism for projecting a pattern from a mask onto a substrate such as a semiconductor wafer. In fields such as semiconductor lithography, it is necessary to create images on the semiconductor wafer that contain minimum feature sizes at the resolution limit or critical dimension (CD). Semiconductor lithography typically includes the steps of applying a photoresist (also known as an etchant) coating on the top surface of the semiconductor wafer (e.g., a thin film stack) and exposing the photoresist to a pattern. The semiconductor wafer is then transferred to a developing chamber to remove the exposed etchant, which is soluble in an aqueous developer solution. As a result, a patterned photoresist layer is present on the top surface of the wafer. Summary of the Invention

[0003] According to one aspect of an embodiment of the present disclosure, a method for fabricating a semiconductor device includes the following steps: forming a photoresist layer on a substrate; selectively exposing the photoresist layer to EUV radiation; and developing the selectively exposed photoresist layer. The photoresist layer is composed of a solvent and a photosensitive compound, wherein the photosensitive compound is dissolved in the solvent and comprises a molecular cluster compound that binds hexameric tin and two chlorine ligands.

[0004] According to one aspect of an embodiment of the present disclosure, an extreme ultraviolet lithography (EUVL) method includes the following steps: turning on a droplet generator to spray metal droplets toward an excitation region in front of a collector; turning on a laser source to emit laser light toward the excitation region so that the metal droplets are heated by the laser light to generate EUV radiation; directing the EUV radiation toward a reflective mask in an exposure apparatus using one or more first optical devices; and directing the EUV radiation reflected by the reflective mask toward a photoresist-coated substrate in the exposure apparatus using one or more second optical devices. The photoresist includes a solvent and a photosensitive compound, wherein the photosensitive compound is dissolved in the solvent and comprises the following formula (I):

[0005] (RSn)6O4(R'CO2)4(R”CO2)4X2(I)

[0006] wherein X is a halide anion, R is an alkyl group, and each of R, R' and R" is one of the alkyl groups shown below:

[0007]

[0008] According to one aspect of an embodiment of the present disclosure, a photoresist includes a solvent and a photosensitive compound. The photosensitive compound is dissolved in the solvent and has the following formula (I):

[0009] (RSn)6O4(R'CO2)4(R”CO2)4X2(I)

[0010] wherein X is a halide anion, R is an alkyl group, and each of R, R' and R" is one of the alkyl groups shown below:

[0011] BRIEF DESCRIPTION OF THE DRAWINGS

[0012] The present disclosure is best understood from the following detailed description in conjunction with the accompanying drawings. Note that, in accordance with standard practice in the industry, various features are not drawn to scale and are for illustration purposes only. In fact, the dimensions of the various features may be arbitrarily increased or decreased for clarity of discussion.

[0013] Figure 1A is a schematic diagram of an EUV lithography tool having an LPP-based EUV radiation source according to some embodiments of the present disclosure;

[0014] Figure 1B is a simplified schematic diagram of details of an extreme ultraviolet lithography tool according to an embodiment of the present disclosure, showing exposure of a photoresist-coated substrate with a patterned EUV beam;

[0015] Figure 2 is a cross-sectional view of an EUV mask constructed according to some embodiments of the present disclosure;

[0016] Figure 3 、 Figure 4 and Figure 5 Schematic partial cross-sectional side views of a semiconductor device at various stages of fabrication according to various aspects of the present disclosure;

[0017] Figure 6 shows a top view of a photoresist segment having a half-pitch (HP) of 22 nm that can be observed using a scanning electron microscope (SEM) according to some embodiments;

[0018] Figure 7 For the Figure 6 A cross-sectional view of line A'-A;

[0019] Figure 8 and Figure 9 The results show that the irradiation rate of the EUV radiation at 200±10mJ / cm2 according to some embodiments is 0.01% and 0.01% respectively. 2A top view of the photoresist layer after exposure to a dose of 16 nm and 18 nm was formed, forming photoresist segments with half-pitch (HP) of 16 nm and 18 nm, respectively. These photoresist segments can be observed using a scanning electron microscope (SEM);

[0020] Figure 10 Schematic partial cross-sectional side views of a semiconductor device at various stages of fabrication according to various aspects of the present disclosure.

[0021]

Explanation of symbols

[0022] 10: EUV lithography system

[0023] 30:Substrate

[0024] 32: conductive layer

[0025] 34: Reflective multilayer structure

[0026] 36: Covering layer

[0027] 38: buffer layer

[0028] 40: Absorption layer

[0029] 45:Semiconductor device

[0030] 48:Substrate

[0031] 50: Material layer

[0032] 50A, 50B: Section

[0033] 60: Photoresist layer

[0034] 60A, 60B: Photoresist section

[0035] 62:Solvent

[0036] 64: Photosensitizing compounds

[0037] 66: Platinum

[0038] 68: Dielectric layer

[0039] 100:EUV radiation source

[0040] 105: Chamber

[0041] 110: Collector

[0042] 115: Target droplet generator

[0043] 120: Nozzle

[0044] 125:Droplet catcher

[0045] 200: Exposure device

[0046] 205a~205e: Optical devices

[0047] 208:Substrate table

[0048] 210: Photoresist coated substrate

[0049] 300: Excitation laser source

[0050] 302: Exposure process

[0051] 310: Laser generator

[0052] 320: Laser Guided Optics

[0053] 330: Focusing device

[0054] A'-A: line

[0055] BF: bottom layer

[0056] DP: target droplet

[0057] DP1, DP2: dampers

[0058] EUV: Extreme Ultraviolet

[0059] LR1: Laser

[0060] LR2: Excitation laser

[0061] MF: Baseline layer

[0062] PP1, PP2: base plate

[0063] PR1~PR3: Photoresist segment

[0064] ZE:EUV light emitter DETAILED DESCRIPTION

[0065] The following disclosure provides many different embodiments or examples for implementing the different features of the provided subject matter. Specific examples of components and arrangements are described below to simplify the disclosure. Of course, these are merely examples and are not intended to be limiting. For example, in the description below, forming a first feature above or on a second feature may include embodiments in which the first and second features are formed in direct contact, and may also include embodiments in which additional features are formed between the first and second features so that the first and second features may not be in direct contact. In addition, the disclosure may repeat element symbols or letters in various examples. This repetition is for simplicity and clarity and does not, in itself, specify the relationship between the various embodiments or configurations discussed.

[0066] Furthermore, for ease of description, spatially relative terms, such as "below," "beneath," "beneath," "above," and "above," may be used herein to describe the relationship of one element or feature to another element or feature as illustrated in the figures. Spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. The device may be otherwise oriented (rotated 90 degrees or at other orientations), and the spatially relative descriptors used herein should be interpreted accordingly.

[0067] Figure 1A Schematic diagram of an EUV lithography system 10 constructed according to some embodiments. The EUV lithography system 10 may also be generally referred to as a scanner, which is used to perform a lithography exposure process using a corresponding radiation source and exposure mode. The EUV lithography system 10 is designed to expose a photoresist layer using EUV light or EUV radiation. The photoresist layer is a material that is sensitive to EUV light. The EUV lithography system 10 uses a radiation source 100 to generate EUV light, such as EUV light having a wavelength in a range between about 1 nm and about 100 nm. In a specific example, the radiation source 100 generates EUV light having a wavelength centered at about 13.5 nm. Therefore, the radiation source 100 is also referred to as an EUV radiation source 100.

[0068] Extreme ultraviolet (EUV) lithography is widely used, for example, in the 20-nanometer (nm) technology node due to its ability to achieve small semiconductor device dimensions. Metal oxide-based photoresists, such as tin-based coating materials, exhibit excellent absorption of far-ultraviolet (FUV) light with a wavelength of 193 nm and extreme ultraviolet (EUV) light with a wavelength of 13.5 nm, and are more effective at EUV absorption than organic polymers. While metal oxide photoresists offer excellent lithographic patterns, they are sensitive to air and moisture and are prone to forming microcrystalline particles, which increases surface defects and negatively impacts overall coating quality.

[0069] The present disclosure provides a novel photoresist having hexameric tin clusters and two chlorine ligands. These two chlorine ligands can disrupt the molecular symmetry of the photoresist, preventing the formation of microcrystalline particles. In particular, the chlorine atoms can absorb EUV light, thereby enhancing the photosensitivity of the photoresist. As a result, the photoresist can form a thin and smooth film over a large area with reduced surface defects. Various aspects of the present disclosure will be discussed below. Figures 1A to 10 First, we will refer to Figure 1A 、 Figure 1B and Figure 2 Next, we will discuss the EUV lithography system. Figures 3 to 10 Discusses details of new photoresists and the lithography processes that use them.

[0070] The advanced lithography processes, methods, and materials described in this disclosure can be used in many applications, including fin-type field effect transistors (FinFETs) and gate-all-around (GAA) FETs. For example, fins can be patterned to create relatively tight spacing between features, for which the disclosure is well suited. Furthermore, spacers used to form the fins of FinFETs can be processed according to the disclosure.

[0071] To address the Moore's Law trend of shrinking chip device sizes and the demand for higher-performance chips in mobile electronic devices like smartphones, which offer computing, multitasking, and even workstation capabilities, a shorter-wavelength lithography exposure system is desirable. Extreme ultraviolet (EUV) lithography utilizes an EUV radiation source that emits EUV light with a wavelength of approximately 13.5 nm. Because this wavelength falls within the range of X-ray radiation, EUV radiation sources are also known as soft X-ray radiation sources. The EUV light emitted by laser-produced plasma (LPP) is collected by a collector mirror and reflected onto a patterned mask.

[0072] Figure 1A FIG2 is a schematic diagram of an EUV lithography tool having an EUV radiation source based on LPP according to some embodiments of the present disclosure. The EUV lithography system includes an EUV radiation source 100 for generating EUV radiation, an exposure device 200 such as a scanner, and an excitation laser source 300. Figure 1A As shown, in some embodiments, an EUV radiation source 100 and an exposure device 200 are mounted on a reference layer MF in a cleanroom, while an excitation laser source 300 is mounted in a bottom layer BF located below the reference layer MF. Each of the EUV radiation source 100 and the exposure device 200 is placed above base plates PP1 and PP2, respectively, via dampers DP1 and DP2. The EUV radiation source 100 and the exposure device 200 are coupled to each other via a coupling mechanism, which may include a focusing unit.

[0073] The EUV lithography system is designed to expose a resist layer to EUV light (also referred to interchangeably herein as EUV radiation). The resist layer is a material sensitive to EUV light. The EUV lithography system employs an EUV radiation source 100 to generate EUV light, such as EUV light having a wavelength between approximately 1 nm and approximately 100 nm. In one specific example, the EUV radiation source 100 generates EUV light having a wavelength centered around approximately 13.5 nm. In this embodiment, the EUV radiation source 100 utilizes a laser-produced plasma (LPP) mechanism to generate EUV radiation.

[0074] Exposure apparatus 200 includes various reflective optical elements, such as convex / concave / flat mirrors, a mask holding mechanism including a mask stage, and a wafer holding mechanism. EUV radiation generated by EUV radiation source 100 is directed by the reflective optical elements onto a mask secured to the mask stage. In some embodiments, the mask stage includes an electrostatic chuck for securing the mask.

[0075] Figure 1B A simplified schematic diagram of details of an extreme ultraviolet lithography tool according to an embodiment of the present disclosure is shown, showing exposure of a photoresist-coated substrate 210 mounted on a substrate stage 208 of an exposure apparatus 200 using a patterned EUV beam. The exposure apparatus 200 is an integrated circuit lithography tool provided with one or more optical devices 205a, 205b, such as a stepper, a scanner, a step and scan system, a direct write system, a device using a contact and / or proximity mask, etc., for example, a patterning optical device 205c such as a mask plate for irradiating the EUV beam to produce a patterned beam, and one or more reduction projection optical devices 205d, 205e for projecting the patterned beam onto the photoresist-coated substrate 210. Mechanical components (not shown) may be provided to produce controlled relative motion between the photoresist-coated substrate 210 and the patterning optical device 205c. As shown in FIG. Figure 2 As further shown, the EUVL tool includes an EUV radiation source 100 including an EUV light radiator ZE that emits EUV light in a chamber 105 , which is reflected by a collector 110 along a path into an exposure device 200 to illuminate a photoresist coated substrate 210 .

[0076] As used herein, the term "optical device" is intended to be broadly interpreted to include, but not necessarily be limited to, one or more elements that reflect and / or transmit and / or act on incident light, and includes, but is not limited to, one or more lenses, windows, filters, wedges, prisms, grisms, gratings, transmission fibers, etalons, diffusers, homogenizers, detectors and other instrumentation components, apertures, axicons, and mirrors including multilayer mirrors, near-normal-incidence mirrors, grazing-incidence mirrors, specular mirrors, diffuse mirrors, and combinations thereof. Furthermore, unless otherwise indicated, the term "optical device" as used herein refers to, but is not limited to, elements that operate solely or advantageously within one or more specific wavelength ranges, such as, for example, EUV output wavelengths, illumination laser wavelengths, wavelengths suitable for metrology, or any other specific wavelength.

[0077] In various embodiments of the present disclosure, the photoresist-coated substrate 210 is a semiconductor wafer, such as a silicon wafer or other types of wafers to be patterned.

[0078] In some embodiments, the EUVL tool further includes other modules or is integrated (or coupled) with other modules.

[0079] like Figure 1A As shown, EUV radiation source 100 includes a target droplet generator 115 and a collector 110 surrounded by a chamber 105. Collector 110 is, for example, a laser-produced plasma (LPP) collector. In various embodiments, target droplet generator 115 includes a reservoir for holding a source material and a nozzle 120 through which target droplets DP of the source material are supplied into chamber 105.

[0080] In some embodiments, the target droplets DP are metal droplets of tin (Sn), lithium (Li), or an alloy of Sn and Li. In some embodiments, each of the target droplets DP has a diameter in the range of about 10 micrometers (μm) to about 100 μm. For example, in one embodiment, the target droplets DP are tin droplets having a diameter of about 10 μm to about 100 μm. In other embodiments, the target droplets DP are tin droplets having a diameter of about 25 μm to about 50 μm. In some embodiments, the target droplets DP are supplied via the nozzle 120 at a rate of about 50 droplets / second (i.e., a spraying frequency of about 50 Hz) to about 50,000 droplets / second (i.e., a spraying frequency of about 50 kHz).

[0081] Return to view Figure 1AThe excitation laser LR2 generated by the excitation laser source 300 is a pulsed laser. The laser pulse LR2 is generated by the excitation laser source 300. The excitation laser source 300 may include a laser generator 310, a laser guiding optical device 320, and a focusing device 330. In some embodiments, the laser generator 310 includes a carbon dioxide (CO2) or a neodymium-doped yttrium aluminum garnet (Nd:YAG) laser source having a wavelength in the infrared region of the electromagnetic spectrum. For example, in an embodiment, the laser generator 310 has a wavelength of approximately 9.4 μm or approximately 10.6 μm. The laser light LR1 generated by the laser generator 310 is guided by the laser guiding optical device 320 and focused by the focusing device 330 into the excitation laser light LR2, which is then introduced into the EUV radiation source 100.

[0082] In some embodiments, the excitation laser LR2 includes a preheating laser and a main laser. In these embodiments, the preheating laser pulse (interchangeably referred to herein as a "pre-pulse") is used to heat (or preheat) a given target droplet to produce a low-density target plume having multiple smaller droplets. This low-density target plume is then heated (or reheated) by the pulse of the main laser, thereby producing more EUV light emission.

[0083] In various embodiments, the preheating laser pulses have a spot size of approximately 100 μm or less, and the main laser pulses have a spot size in the range of approximately 150 μm to approximately 300 μm. In some embodiments, the preheating laser pulses and the main laser pulses have a pulse duration in the range of approximately 10 ns to approximately 50 ns and a pulse frequency in the range of approximately 1 kHz to approximately 100 kHz. In various embodiments, the preheating laser and the main laser have an average power in the range of approximately 1 kilowatt (kW) to approximately 50 kW. In embodiments, the pulse frequency of the excitation laser LR2 is matched (e.g., synchronized) with the ejection frequency of the target droplets DP.

[0084] Laser light LR2 is directed through a window (or lens) into an excitation zone ZE in front of the collector 110. The window is made of a suitable material that is substantially transparent to the laser beam. The generation of pulsed laser light is synchronized with the ejection of target droplets DP through the nozzle 120. As the target droplets pass through the excitation zone, the pre-pulse heats the target droplets and converts them into a low-density target plume. The delay between the pre-pulse and the main pulse is controlled to allow the target plume to form and expand to an optimal size and geometry. In various embodiments, the pre-pulse and the main pulse have the same pulse duration and peak power. When the main pulse heats the target plume, a high-temperature plasma is generated. The plasma emits EUV radiation EUV that is collected by the collector 110. The collector 110 further reflects and focuses the EUV radiation for use in the lithography exposure process performed by the exposure device 200. The droplet catcher 125 is used to capture excess target droplets. For example, some target droplets may be intentionally omitted by the laser pulse.

[0085] In some embodiments, the collector 110 is designed with an appropriate coating material and shape to act as a mirror for EUV collection, reflection, and focusing. In some embodiments, the collector 110 is designed with an elliptical geometry. In some embodiments, the coating material of the collector 110 is similar to the reflective multilayer of the EUV mask. In some instances, the coating material of the collector 110 includes a ML (such as a plurality of Mo / Si film pairs) and may further include a capping layer (such as Ru) coated on the ML to substantially reflect EUV light. In some embodiments, the collector 110 may further include a grating structure designed to effectively scatter the laser beam directed onto the collector 110. For example, a silicon nitride layer is coated on the collector 110 and patterned to have a grating pattern.

[0086] Throughout this disclosure, the terms mask, reticle, and reticle plate are used interchangeably. In this embodiment, patterned optical device 205c is a reflective mask 205c. Reflective mask 205c also includes a reflective ML deposited on a substrate. The ML comprises a plurality of film pairs, such as molybdenum-silicon (Mo / Si) film pairs (e.g., a molybdenum layer above or below the silicon layer in each film pair). Alternatively, the ML may comprise a molybdenum-beryllium (Mo / Be) film pair, or other suitable materials that are highly reflective of EUV light.

[0087] Mask 205c may further include a capping layer, such as ruthenium (Ru), disposed on the ML for protection. Mask 205c further includes an absorber layer deposited on the ML. The absorber layer is patterned to define layers of an integrated circuit (IC), as discussed in more detail below according to various aspects of the present disclosure. Alternatively, another reflective layer may be deposited over the ML and patterned to define IC layers, thereby forming an EUV phase-shift mask.

[0088] The mask 205c and its manufacturing method are further described according to some embodiments. In some embodiments, the mask manufacturing process includes two operations: a blank mask manufacturing process and a mask patterning process. In the blank mask manufacturing process, a blank mask is formed by depositing a suitable layer (e.g., a reflective multilayer) on a suitable substrate. The blank mask is then patterned during the mask patterning process to achieve the desired design of an integrated circuit (IC) layer. The patterned mask is then used to transfer the circuit pattern (e.g., the design of the IC layer) to a semiconductor wafer. The pattern can be transferred over and over to multiple wafers via various lithography processes. A set of masks is used to build a complete IC.

[0089] An example of a reflective mask 205c is Figure 2. The reflective mask 205c in the illustrated embodiment is an EUV mask and includes a substrate 30 made of LTEM. LTEM materials may include SiO2 doped with TiO2 and / or other low thermal expansion materials known in the art. In some embodiments, a conductive layer 32 is additionally disposed beneath the backside of the LTEM substrate 30 for electrostatic clamping purposes. In one example, the conductive layer 32 comprises chromium nitride (CrN), although other suitable compositions are possible.

[0090] The reflective mask 205c includes a reflective multilayer (ML) structure 34 disposed above the LTEM substrate 30. The ML structure 34 can be selected to provide high reflectivity for a selected radiation type / wavelength. The ML structure 34 includes a plurality of film pairs, such as Mo / Si film pairs (e.g., a molybdenum layer above or below the silicon layer in each film pair). Alternatively, the ML structure 34 can include a Mo / Be film pair, or any material having a refractive index difference that is highly reflective at EUV wavelengths.

[0091] Still see Figure 2 EUV mask 205c also includes a capping layer 36 disposed over ML structure 34 to prevent ML oxidation. EUV mask 205c may further include a buffer layer 38 disposed over capping layer 36 to serve as an etch stop during patterning or repairing of the absorber layer, as described below. Buffer layer 38 has different etching characteristics than the absorber layer above it. In various embodiments, buffer layer 38 includes ruthenium (Ru), a Ru compound such as RuB, RuSi, chromium (Cr), chromium oxide, and chromium nitride.

[0092] EUV mask 205c also includes an absorber layer 40 (also referred to as an absorber layer) formed over buffer layer 38. In some embodiments, absorber layer 40 absorbs EUV radiation directed onto the mask. In various embodiments, the absorber layer can be made of tantalum boron nitride (TaBN), tantalum boron oxide (TaBO), or chromium (Cr), radium (Ra), or a suitable oxide or nitride (or alloy) of one or more of the following materials: actinium, radium, tellurium, zinc, copper, and aluminum.

[0093] Figure 3 、 Figure 4 、 Figure 5 and Figure 10Schematic partial cross-sectional side views of a semiconductor device 45 at various stages of fabrication according to various aspects of the present disclosure. The semiconductor device 45 may comprise an integrated circuit (IC) die, a system on chip (SoC), or a portion thereof, and may include various passive and active microelectronic devices such as resistors, capacitors, inductors, diodes, metal-oxide semiconductor field effect transistors (MOSFETs), complementary metal-oxide semiconductor (CMOS) transistors, bipolar junction transistors (BJTs), laterally diffused MOS (LDMOS) transistors, high-power MOS transistors, or other types of transistors.

[0094] See Figure 3 , semiconductor device 45 includes a substrate 48. In some embodiments, substrate 48 is a silicon substrate doped with a p-type dopant such as boron (e.g., a p-type substrate). Alternatively, substrate 48 may be another suitable semiconductor material. For example, substrate 48 may be a silicon substrate doped with an n-type dopant such as phosphorus or arsenic (an n-type substrate). Substrate 48 may include other elemental semiconductors, such as germanium and diamond. Substrate 48 may alternatively include a compound semiconductor and / or an alloy semiconductor. In addition, substrate 48 may include an epitaxial layer, may be strained to improve performance, and may include a silicon-on-insulator (SOI) structure.

[0095] In some embodiments, substrate 48 is substantially conductive or semiconductive. The resistance may be less than about 10 3 Ohm-meter. In some embodiments, substrate 48 comprises a metal, metal alloy, or metal nitride / sulfide / selenide / oxide / silicide having the formula MX a , where M is a metal, and X is N, S, Se, O, Si, and where "a" is in the range of about 0.4 to 2.5. For example, substrate 48 may contain Ti, Al, Co, Ru, TiN, WN2, or TaN.

[0096] In some other embodiments, the substrate 48 comprises a dielectric material having a dielectric constant in the range of about 1 to about 40. In some other embodiments, the substrate 48 comprises Si, a metal oxide, or a metal nitride, wherein the formula is MX b, wherein M is a metal or Si, and X is N or O, and wherein "b" is in the range of about 0.4 to 2.5. For example, substrate 48 may contain SiO2, silicon nitride, aluminum oxide, hafnium oxide, or lanthanum oxide.

[0097] A material layer 50 is formed over substrate 48. Material layer 50 can be patterned via a lithographic process and is therefore also referred to as a patternable layer. In one embodiment, material layer 50 comprises a dielectric material, such as silicon oxide or silicon nitride. In another embodiment, material layer 50 comprises a metal. In yet another embodiment, material layer 50 comprises a semiconductor material.

[0098] In some embodiments, material layer 50 has different optical properties than the photoresist. For example, material layer 50 has different n, k, or T values ​​than the photoresist. In some embodiments, material layer 50 and the overlying photoresist layer have different etch resistances. In some embodiments, material layer 50 contains etch-resistant molecules. It should be understood that in other embodiments, substrate 48 and material layer 50 may each include additional suitable material compositions.

[0099] A photoresist layer 60 is formed above the material layer 50. The photoresist layer 60 can be formed by a spin coating process. For example, the photoresist layer 60 can be spin-coated on a 4-inch silicon wafer. A few milliliters of the composition of the photoresist layer 60 are placed (distributed) on the silicon wafer, and the silicon wafer is rotated at a speed of several 1000±10 rpm (for example, 1500 rpm) for 10 to 20 seconds, for example, 10 seconds, and then at a rotation speed of 2000±10 rpm for 25 to 35 seconds, for example, 25 seconds. The photoresist layer 60 is then baked at 60°C to 100°C for 60 to 70 seconds, for example, 60 seconds. In some embodiments, the thickness of the photoresist layer 60 is in the range of 20nm to 25nm.

[0100] Photoresist layer 60 includes a solvent 62 and a photosensitive compound 64 dissolved in solvent 62. Solvent 62 includes an appropriate organic solvent for adjusting viscosity. Such organic solvents include, but are not limited to, 4-methyl-2-pentanol. The content of photosensitive compound 64 in 4-methyl-2-pentanol is 1.2 wt % to 1.5 wt % relative to photoresist layer 60.

[0101] The photosensitive compound 64 may be a compound containing a metal oxide. For example, the photosensitive compound 64 is a compound containing tin oxide and has the following general formula (I):

[0102] (RSn)6O4(R'CO2)4(R”CO2)4X2(I).

[0103] Here, X in the above formula (I) is an anion having a halogen anion, such as a fluorine (F) anion, a chloride (Cl) anion, a bromide (Br) anion, or an iodine (I) anion. Each of R, R', and R" is one of the alkyl groups shown below:

[0104]

[0105] In some embodiments, the photosensitive compound 64 has the following formula (I):

[0106] (RSn)6O4(R'CO2)4(R"CO2)4Cl2, and can be the following structure:

[0107]

[0108] The photosensitive compound 64 has two chlorine ligands. The chlorine ligands can destroy the molecular symmetry, thereby avoiding the formation of microcrystalline particles. In particular, the chlorine atoms can absorb EUV light, thereby increasing the photosensitivity of the photoresist layer 60. The photosensitive compound 64 has at least one ladder structure. For example, the photosensitive compound 64 includes a plurality of six-tin ladder clusters. By introducing this ladder structure into the photosensitive compound 64, the photoresist layer 60 can form a thin and smooth film over a large area. In some embodiments where the material layer 50 is a dielectric layer (e.g., a silicon oxide layer), the photoresist layer 60 can be firmly bonded to the material layer 50.

[0109] In one example, formula (I) can be (n-BuSn)6O4(CH3CO2)8Cl2. The term "Bu" refers to a butyl group. The molecular structure of (n-BuSn)6O4(CH3CO2)8Cl2, as determined by single crystal X-ray diffraction studies, is shown below:

[0110]

[0111] In some embodiments, photosensitive compound 64 is synthesized by reacting RSnCl 3 with compound MC-1 and compound MC-2, as shown in the following general reaction scheme 1:

[0112] Solution 1

[0113]

[0114] Compound MC-1 and Compound MC-2 are silver carboxylates. In some embodiments, in Scheme 1, R' of Compound MC-1 and R" of Compound MC-2 are the same and are represented by one of the following compounds:

[0115]

[0116] In some embodiments, R' of compound MC-1 and R" of compound MC-2 are the same. In other words, compound MC-1 and compound MC-2 have the same chemical formula. In this case, the amount of RSnCl3 is 1 mol relative to the total of 2.5 mol of compound MC-1 and compound MC-2 in Scheme 1.

[0117] In some embodiments, in Scheme 1, R' of compound MC-1 and R" of compound MC-2 are different from each other and are represented by the following compounds:

[0118]

[0119] As shown above, the size of R' of compound MC-1 is different from the size of R" of compound MC-2. For example, the size of R' of compound MC-1 is smaller than the size of R" of compound MC-2. In some embodiments where the sizes of R' of compound MC-1 and R" of compound MC-2 are different, the amount of RSnCl3 is 1 mole relative to 1 mole of compound MC-1 and 1 mole of compound MC-2 in Scheme 1.

[0120] In Scheme 1, RSnCl 3 , compound MC-1 and compound MC-2 are added to dichloromethane (DCM), and the mixture is stirred under reflux for 8 to 9 hours, for example, 8 hours. The crude product is purified by recrystallization to obtain solid photosensitive compound 64.

[0121] See now Figure 4 , an exposure process 302 is performed to selectively expose the photoresist layer 60 to EUV radiation. The exposure process 302 applies EUV radiation to areas of the photoresist layer 60. In some embodiments, a low dose EUV patterning photoresist layer may be used, for example, at 100 mJ / cm 2 Up to 200mJ / cm 2 In the range of, for example, 100mJ / cm 2 After the photoresist layer 60 is exposed, the photoresist layer 60 is baked at 80° C. to 100° C. for 1 minute to 2 minutes, for example, 1 minute.

[0122] See now Figure 5 The selectively exposed photoresist layer 60 is developed. For example, subsequent lithography processes (e.g., post-exposure baking, development, rinsing, etc.) may be performed to form a patterned photoresist, which, for simplicity, is illustrated herein as photoresist segments 60A and 60B separated by grooves. The selectively exposed photoresist layer 60 is developed using acetone for 60 seconds and then baked at 80° C. to 100° C.

[0123] The photoresist segments 60A and 60B are defect-free over a large area (e.g., 1.0±0.1 mm×0.7±0.1 mm). This is also supported by 12 SEM images, three of which are shown below. Figure 6 A top view of a photoresist segment PR1 having a half-pinch (HP) of 22±0.1 nm, which can be observed using a scanning electron microscope (SEM), is shown in accordance with some embodiments. Figure 7 For the Figure 6 A'-A line cross-sectional view. Figure 6 and Figure 7 These photoresist segments PR1 are derived from a photoresist layer, which is spin-coated on a dielectric layer 68 above a substrate SB and is coated using EUV at 200±10 mJ / cm 2 The photoresist segment PR1 is exposed to a dose of 100 nm and coated with platinum (Pt) 66 for SEM measurement. The thickness of the photoresist segment PR1 is in the range of 6 nm to 8 nm, for example, 7 nm. Figure 6 and Figure 7 No defects were observed in the photoresist segment PR1. The photoresist segment PR1 was of high quality and had no defects over a large area. For example, the photoresist segment PR1 remained intact and had reduced line-edge roughness (LER) and reduced line-width roughness (LWR).

[0124] Figure 8 and Figure 9 The results show that the irradiation rate of the EUV radiation at 200±10mJ / cm2 according to some embodiments is 0.01% and 0.01% respectively. 2 The top view of the photoresist layer after exposure to a dose of 100 nm forms photoresist segments PR2 and PR3 with half-pinch (HP) values ​​of 16±0.1 nm and 18±0.1 nm, respectively. The photoresist segments PR2 and PR3 can be observed using a scanning electron microscope (SEM). Figure 8 and Figure 9 The photoresist segments PR2 and PR3 are of high quality and free of defects over a large area. For example, the photoresist segments PR2 and PR3 remain intact and have reduced line-edge roughness (LER) and reduced line-width roughness (LWR).

[0125] Using the patterned photoresist as a mask, additional fabrication processes such as etching or implantation can be performed. Figure 10, the material layer 50 is etched into segments 50A and 50B separated by a groove. Thereafter, the patterned photoresist may be removed by a photoresist removal process known in the art, such as a stripping or ashing process.

[0126] Although the above discussion uses EUV lithography as an example, it should be understood that various aspects of the photoresist layer may also be applied to other types of lithography, such as electron beam lithography.

[0127] Based on the above discussion, it can be seen that the present disclosure provides advantages over conventional methods. However, it should be understood that other embodiments may provide additional advantages, and not all advantages must be disclosed in this article, and the specific advantages of all embodiments are not required. One advantage is that the photosensitive compound has two chlorine ligands. The chlorine ligands can destroy the molecular symmetry, thereby avoiding the formation of microcrystalline particles. Another advantage is that the chlorine atoms can absorb EUV light, thereby enhancing the photosensitivity of the photoresist layer. Another advantage is that since the photosensitive compound includes multiple six-tin ladder clusters, the photoresist layer can form a thin and smooth film over a large area. When adjacent carboxylates are decomposed by EUV light, the presence of chloride can also enhance photopolymerization. Chloride will become a bridging ligand between the two tin metals. This new process will provide SnO x Cl y film instead of SnO2.

[0128] In some embodiments, a method for manufacturing a semiconductor device includes the following steps: forming a photoresist layer on a substrate; selectively exposing the photoresist layer to EUV radiation; and developing the selectively exposed photoresist layer. The composition of the photoresist layer includes a solvent and a photosensitive compound, the photosensitive compound being dissolved in the solvent and consisting of a molecular cluster compound that combines hexameric tin and two chlorine ligands. In some embodiments, the molecular cluster compound is (RSn)6O4(R'CO2)4(R"CO2)4Cl2. In some embodiments, the size of R' is smaller than the size of R". In some embodiments, R' and R" have the same structural formula. In some embodiments, the molecular cluster compound is (n-BuSn)6O4(CH3CO2)8Cl2. In some embodiments, the EUV radiation has a strength of 100mJ / cm 2 Up to 200mJ / cm 2 In some embodiments, the content of the photosensitive compound in the solvent relative to the photoresist layer is 1.2 wt % to 1.5 wt %.

[0129] In some embodiments, an extreme ultraviolet lithography (EUVL) method includes the following steps: turning on a droplet generator to spray metal droplets toward an excitation region in front of a collector; turning on a laser source to emit laser light toward the excitation region so that the metal droplets are heated by the laser light to generate EUV radiation; directing the EUV radiation toward a reflective mask in an exposure apparatus using one or more first optical devices; and directing the EUV radiation reflected by the reflective mask toward a photoresist-coated substrate in the exposure apparatus using one or more second optical devices. The photoresist includes a solvent and a photosensitive compound, wherein the photosensitive compound is dissolved in the solvent and comprises the following formula (I):

[0130] (RSn)6O4(R'CO2)4(R”CO2)4X2(I)

[0131] wherein X is a halide anion, R is an alkyl group, and each of R, R' and R" is one of the alkyl groups shown below:

[0132]

[0133] In some embodiments, formula (I) is (RSn)6O4(R'CO2)4(R"CO2)4Cl2. In some embodiments, the photosensitive compound is formed by adding RSnCl3 and a first silver carboxylate salt to an organic solvent to form a mixture; and stirring the mixture under reflux, and purifying the mixture by recrystallization. In some embodiments, the organic solvent is dichloromethane (DCM). In some embodiments, the first silver carboxylate salt is selected from the following compounds:

[0134]

[0135]

[0136] In some embodiments, the photosensitive compound is formed by the following steps: adding RSnCl3, a first silver carboxylate salt, and a second silver carboxylate salt different from the first silver carboxylate salt to an organic solvent to form a mixture; and stirring the mixture under reflux, and purifying the mixture by recrystallization. In some embodiments, the size of the first silver carboxylate salt is larger than the size of the second silver carboxylate salt. In some embodiments, the first silver carboxylate salt and the second silver carboxylate salt are selected from the following compounds:

[0137]

[0138]

[0139] In some embodiments, the photoresist comprises a solvent and a photosensitive compound, wherein the photosensitive compound is dissolved in the solvent and comprises the following formula (I):

[0140] (RSn)6O4(R'CO2)4(R”CO2)4X2(I)

[0141] wherein X is a halide anion, R is an alkyl group, and each of R, R' and R" is one of the alkyl groups shown below:

[0142]

[0143] In some embodiments, formula (I) is (RSn)6O4(R'CO2)4(R"CO2)4Cl2. In some embodiments, formula (I) is (n-BuSn)6O4(CH3CO2)8Cl2. In some embodiments, the photosensitive compound has at least one ladder structure. In some embodiments, the photosensitive compound has multiple hexatin ladder clusters.

[0144] The features of several embodiments or examples are summarized above so that those skilled in the art can better understand the various aspects of the present disclosure. Those skilled in the art will understand that they can easily use this disclosure as a basis for designing or modifying other processes and structures to achieve the same purposes and / or achieve the same advantages as the embodiments or examples described herein. Those skilled in the art will also recognize that these equivalent constructions do not depart from the spirit and scope of the present disclosure, and that various changes, substitutions, and modifications may be made to these equivalent constructions without departing from the spirit and scope of the present disclosure.

Claims

1. A method for manufacturing a semiconductor device, characterized in that: The following steps are involved: forming a photoresist layer on a substrate; selectively exposing the photoresist layer to extreme ultraviolet radiation; and developing the selectively exposed photoresist layer, The photoresist layer has a composition comprising: a solvent; and a photosensitizing compound dissolved in the solvent and consisting of a molecular cluster compound bound to hexameric tin and two chlorine ligands; Wherein, the photosensitizing compound has the following structure:

2. The method according to claim 1, wherein The molecular cluster compound is (RSn)6O4(R'CO2)4(R”CO2)4Cl2.

3. The method according to claim 2, wherein The size of R' is smaller than the size of R".

4. The method according to claim 2, wherein wherein the R' and the R" have the same structural formula.

5. The method according to claim 1, wherein The molecular cluster compound is (n-BuSn)6O4(CH3CO2)8Cl2.

6. The method according to claim 1, wherein The EUV radiation has a radiation intensity of 100 mJ / cm 2 Up to 200mJ / cm 2 A dose within the range.

7. The method according to claim 1, wherein The content of the photosensitive compound in the solvent relative to the photoresist layer is 1.2 wt % to 1.5 wt %.

8. An extreme ultraviolet lithography method, characterized in that: The following steps are involved: Turning on a droplet generator to spray a metal droplet onto an excitation area in front of a collector; Turning on a laser source to emit a laser toward the excitation region so that the metal droplet is heated by the laser to generate extreme ultraviolet radiation; directing the EUV radiation toward a reflective mask in an exposure apparatus using one or more first optical devices; and directing the EUV radiation reflected by the reflective mask toward a photoresist-coated substrate in the exposure apparatus using one or more secondary optical devices, The photoresist comprises: a solvent; and A photosensitizing compound, dissolved in the solvent and comprising the following formula (I): (RSn)6O4(R'CO2)4(R”CO2)4X2(I), Where X is a halogen anion, R is an alkyl group, and Each of R, R' and R" is one of the groups shown below: Wherein, the photosensitizing compound has the following structure:

9. The method according to claim 8, wherein Wherein the formula (I) is (RSn)6O4(R'CO2)4(R"CO2)4Cl2.

10. The method according to claim 9, wherein The photosensitive compound is formed by the following steps: Adding RSnCl3 and a first silver carboxylate salt to an organic solvent to form a mixture; and The mixture was stirred under reflux and purified by recrystallization.

11. The method according to claim 10, wherein The organic solvent is dichloromethane (DCM).

12. The method according to claim 10, wherein The first carboxylic acid silver salt is selected from the following compounds:

13. The method according to claim 9, wherein The photosensitive compound is formed by the following steps: Adding RSnCl3, a first silver carboxylate salt, and a second silver carboxylate salt different from the first silver carboxylate salt into an organic solvent to form a mixture; and The mixture was stirred under reflux and purified by recrystallization.

14. The method according to claim 13, wherein The size of the first silver carboxylate salt is larger than that of the second silver carboxylate salt.

15. The method according to claim 13, wherein The first carboxylate silver salt and the second carboxylate silver salt are selected from the following compounds:

16. A photoresist, characterized in that: Include: a solvent; and A photosensitizing compound, dissolved in the solvent and comprising the following formula (I): (RSn)6O4(R'CO2)4(R”CO2)4X2(I), Where X is a halogen anion, R is an alkyl group, and Each of R, R' and R" is one of the groups shown below: Wherein, the photosensitizing compound has the following structure:

17. The photoresist according to claim 16, wherein Wherein the formula (I) is (RSn)6O4(R'CO2)4(R"CO2)4Cl2.

18. The photoresist according to claim 16, wherein Wherein the formula (I) is (n-BuSn)6O4(CH3CO2)8Cl2.

19. The photoresist according to claim 16, wherein The photosensitive compound has at least one ladder structure.

20. The photoresist according to claim 16, wherein The photosensitizing compound has a plurality of hexatin ladder-type clusters.

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