Method and apparatus for coating photoresist over a substrate

Abstract

The present application relates to a method and apparatus for coating photoresist on a substrate. In a method for coating photoresist on a wafer, dispensing photoresist on a wafer from a nozzle is started while the wafer is rotated, and dispensing photoresist is stopped while the wafer is rotated. After dispensing photoresist is started and before dispensing photoresist is stopped, the wafer rotation speed is changed at least 4 times. During dispensing, an arm holding a nozzle can be moved horizontally. The tip of the nozzle can be located at a height of 2.5 mm to 3.5 mm from the wafer.

Description

Technical Field

[0001] The present disclosure generally relates to methods and apparatus for coating photoresist over a substrate. Background Art

[0002] Photolithography is one of the key operations in semiconductor manufacturing processes. Photolithography includes ultraviolet lithography, deep ultraviolet lithography, and extreme ultraviolet lithography (EUVL). Photolithography is usually a high-cost process, and reducing the cost is one of the issues to be addressed. Specifically, in EUV lithography, the cost of photoresist is much higher than that of deep UV photoresist. Summary of the invention

[0003] According to a first aspect of the present disclosure, a method for coating a photoresist onto a wafer is provided, comprising: starting to dispense the photoresist onto the wafer from a nozzle while rotating the wafer; stopping dispensing the photoresist while rotating the wafer; and changing the wafer rotation speed at least 4 times after starting to dispense the photoresist and before stopping dispensing the photoresist.

[0004] According to a second aspect of the present disclosure, a method for coating photoresist on a wafer is provided, comprising: starting to dispense the photoresist from a nozzle while rotating the wafer at a first speed; continuously dispensing the photoresist for a second duration T2 while rotating the wafer at a second speed different from the first speed; continuously dispensing the photoresist for a third duration T3 while rotating the wafer at a third speed different from the second speed; continuously dispensing the photoresist for a fourth duration T4 while rotating the wafer at a fourth speed different from the third speed; continuously dispensing the photoresist while rotating the wafer at a fifth speed and horizontally moving the nozzle from the center of the wafer to the edge of the wafer; and after stopping the movement of the nozzle, stopping dispensing the photoresist while rotating the wafer at a sixth speed different from the fifth speed.

[0005] According to a third aspect of the present disclosure, a photoresist coating device is provided, comprising: a wafer holder configured to support a wafer and rotate the wafer; a nozzle configured to dispense photoresist; an arm coupled to the nozzle and configured to move the nozzle horizontally and vertically; and a control system, comprising a processor and a memory storing a program and a coating recipe, and configured to control the wafer holder, the nozzle and the arm according to the coating recipe, wherein: the program, when executed by the processor, causes the control system to perform the following operations: start dispensing the photoresist from the nozzle while rotating the wafer at a first speed; The invention relates to a method for dispensing photoresist; continuously dispensing the photoresist while rotating the wafer at a second speed different from the first speed; continuously dispensing the photoresist while rotating the wafer at a third speed different from the second speed; continuously dispensing the photoresist while rotating the wafer at a fourth speed different from the third speed; continuously dispensing the photoresist while rotating the wafer at a fifth speed and horizontally moving the nozzle from the center of the wafer to the edge of the wafer; and after stopping the movement of the nozzle, stopping dispensing the photoresist while rotating the wafer at a sixth speed different from the fifth speed. BRIEF DESCRIPTION OF THE DRAWINGS

[0006] Figure 1A and Figure 1B is a schematic diagram of a photoresist coating device according to an embodiment of the present disclosure.

[0007] Figure 2A , Figure 2B , Figure 2C , Figure 2D , Figure 2E and Figure 2F Various stages of a sequential process for coating a photoresist on a wafer / substrate according to an embodiment of the present disclosure are shown. Figure 2G A resist coating sequence (recipe) according to an embodiment of the present disclosure is shown.

[0008] Figure 3 The effect of nozzle height according to an embodiment of the present disclosure is shown.

[0009] Figure 4A , Figure 4B and Figure 4C Various nozzle configurations are shown according to embodiments of the present disclosure.

[0010] Figure 5A , Figure 5B and Figure 5C Various nozzle configurations are shown according to embodiments of the present disclosure.

[0011] Fig. 6A and Figure 6BThe effects of nozzle height and nozzle size are shown according to an embodiment of the present disclosure.

[0012] Fig. 7A and Figure 7B The effect of reducing the amount of resist dispensed according to an embodiment of the present disclosure is shown. DETAILED DESCRIPTION

[0013] It should be understood that the following disclosure provides many different embodiments or examples for realizing different features of the present invention. Specific embodiments and examples of components and arrangements are described below to simplify the present disclosure. Of course, these are only examples and are not intended to be restrictive. For example, the size of the element is not limited to the disclosed range or value, but may depend on the process conditions and / or desired characteristics of the device. In addition, in the following description, forming a first feature above or on a second feature may include an embodiment in which the first feature and the second feature are formed in direct contact, and may also include an additional feature that may be formed between the first feature and the second feature so that the first feature and the second feature may not be in direct contact. For simplicity and clarity, various features may be arbitrarily drawn in different proportions. In the accompanying drawings, some layers / features may be omitted for simplicity.

[0014] In addition, for ease of description, spatially related terms (such as "below", "below", "below", "above", "upper", etc.) may be used herein to describe the relationship of an element or feature shown in the figure relative to another (one or more) element or (one or more) feature. These spatially related terms are intended to cover different orientations of the device in use or operation except for the orientation shown in the figure. The device can be oriented in other ways (rotated 90 degrees or in other orientations), and the spatially related descriptors used in this article can also be interpreted accordingly. In addition, the term "made of..." can mean "including" or "consisting of...". In addition, in the subsequent manufacturing process, there may be one or more additional operations in / between the described operations, and the order of operations may change. In the present disclosure, the phrase "one of A, B and C" means "A, B and / or C" (A; B; C; A and B; A and C; B and C; or A, B and C), and does not mean an element from A, an element from B, and an element from C, unless otherwise specified.

[0015] As mentioned above, reducing the cost of photoresist is one of the key issues in photolithography operations. One of the ways to reduce the cost of photoresist is to reduce the amount of photoresist used (dispensed) per wafer or substrate. However, simply reducing the amount of photoresist dispensed will result in uneven coating of photoresist on the wafer, which will increase the defective pattern of the photoresist after development after exposure.

[0016] In the present disclosure, a method and apparatus for coating a photoresist on a wafer or a substrate are provided, which can reduce the use of photoresist paste without reducing the uniformity of the thickness of the coated photoresist.

[0017] For example, according to one or more embodiments, the resist dispense amount can be reduced to 0.35-0.65 cc (cm2) per 300 mm wafer. 3 ), and for an average resist thickness of about 30-50 nm, the thickness variation (range) is less than 2 nm (greater than zero). In other embodiments, for an average resist thickness of about 30-50 nm, the thickness variation is greater than 0.5 nm to less than about 1.0 nm. In some embodiments, when the average resist thickness is about T0 (nm), the thickness variation is about 1% to about 2% of T0. In some embodiments, the target resist thickness is in the range of about 10 nm to about 120 nm.

[0018] Figure 1A and Figure 1B Schematic diagram of a photoresist coating device according to an embodiment of the present disclosure. A person skilled in the art will understand that Figure 1A and Figure 1B The illustrated apparatus utilizes one or more additional features.

[0019] The photoresist coating apparatus 1000 includes a housing or casing 1001 in which a substrate holder 1003 is disposed. Figure 1AAs shown. The substrate holder is configured to hold a wafer or substrate 1010 by vacuum (vacuum chuck) and includes a motor for rotating the wafer at various speeds. The substrate holder 1003 is also configured to move the wafer up and down. The device 1000 includes a plurality of fluid nozzles, which include a photoresist dispensing nozzle 1021 and an edge cutting solution nozzle 1023, the photoresist dispensing nozzle 1021 being configured to dispense photoresist, and the edge cutting solution nozzle 1023 being configured to dispense solvent to remove the applied photoresist from the edge portion of the wafer. In some embodiments, a plurality of nozzles for different photoresists are provided. The nozzles are respectively coupled to movable arms and can move in the lateral (horizontal) direction and the vertical direction in some embodiments. The movable arm includes one or more of a motor, a gear, a power transmission belt, or other known components to move the nozzle horizontally and / or vertically. The fluid nozzle 1021 is fluidly connected to a photoresist source (e.g., a bottle or tank) 1015 storing photoresist, and the fluid nozzle 1023 is fluidly connected to a solvent source 1050 storing solvent. One or more pumps 1040 having one or more filters and one or more valves are disposed on the fluid path from the photoresist source 1015 to the nozzle 1021, and one or more pumps 1042 having one or more filters and one or more valves are disposed on the fluid path from the solvent source 1050 to the nozzle 1023.

[0020] In some embodiments, the solvent is one or more selected from the following: propylene glycol methyl ether acetate (PGMEA), propylene glycol monomethyl ether (PGME), 1-ethoxy-2-propanol (PGEE), γ-butyrolactone (GBL), cyclohexanone (CHN), ethyl lactate (EL), methanol, ethanol, propanol, n-butanol, acetone, dimethylformamide (DMF), isopropanol (IPA), tetrahydrofuran (THF), methyl isobutyl carbinol (MIBC), n-butyl acetate (nBA), and 2-heptanone (MAK).

[0021] At least a portion of the operation of the photoresist coating apparatus 1000 is controlled by one or more control systems 900, such as Figure 1B As shown, the control system 900 may be communicatively connected to the photoresist coating apparatus 1000 or included in the photoresist coating apparatus 1000 .

[0022] When the control program is executed by the computer, the control system 900 controls the operation of the arm coupled to the nozzles 1021 and 1023 and / or the pump systems 1040, 1042, for example, the rotation of the substrate holder 1003, according to the selected coating recipe. Figure 1BA schematic diagram of a control system 900 for performing control of the photoresist coating device 1000 according to one or more embodiments is also shown. All or part of the process, method and / or operation of the photoresist coating device 1000 can be implemented using computer hardware and a computer program executed thereon. The control system 900 is equipped with a computer 901, which includes an optical disk read-only memory (e.g., CD-ROM or DVD-ROM) drive 905 and a disk drive 906, a keyboard 902, a mouse 903 and a monitor 904. In addition to the optical disk drive 905 and the disk drive 906, the computer 901 is also equipped with one or more processors 911 (e.g., a microprocessing unit (MPU)), a ROM 912 (in which programs such as a boot program are stored), a random access memory (RAM) 913 (connected to the MPU 911, and in which commands of application programs are temporarily stored and a temporary storage area is provided), a hard disk 914 (in which application programs, system programs and data are stored), and a bus 915 (connecting the MPU 911, the ROM 912, etc.). Note that the computer 901 may include a network card (not shown) for providing a connection to a LAN. A program for causing the computer system 900 to perform the functions of the photoresist coating apparatus 1000 may be stored in an optical disk 921 or a magnetic disk 922 inserted into the optical disk drive 905 or the magnetic disk drive 906 and transferred to the hard disk 914. Specifically, one or more coating recipes are stored in one or more of the aforementioned memories.

[0023] Alternatively, the recipe may be transmitted to the computer 901 via a network (not shown) and stored in the hard disk 914. At execution, the recipe is loaded into the RAM 913. The program may be loaded from the optical disk 921 or the disk 922, or directly from the network. The program does not necessarily have to include, for example, an operating system (OS) or a third-party program to enable the computer 901 to perform the functions of the resist coating device 1000. The program may only include a command portion that calls the appropriate function (module) in a controlled mode and obtains the desired result.

[0024] Figures 2A-2F shows the resist coating operation, and Figure 2G Detailed steps (recipes) for a resist coating operation according to the present disclosure are shown. In some embodiments, the recipe for coating the photoresist is stored in a memory of the photoresist coating device. In some embodiments, the recipe is stored in a memory such as a flash memory, a CD-ROM, or a DVD-ROM, and can be copied from one device to another. In addition, in some embodiments, the recipe is distributed from a server to multiple photoresist coating devices.

[0025] like Figure 2AAs shown, the wafer 100 rotates at a predetermined speed. Then, the photoresist is dispensed from the nozzle 120 while the wafer rotates clockwise. Figure 2B In some embodiments, nozzle 120 is located above the center of wafer 100. Photoresist is continuously dispensed while wafer 100 is rotating. Figure 2C Then, the nozzle 120 moves horizontally along the diameter of the wafer while dispensing the photoresist and rotating the wafer, as shown in FIG. Figure 2D As shown. The wafer 120 is rotated while dispensing from the nozzle 120 at the shifted position, such as Figure 2E As shown, however Figure 2F As shown, the dispensing stops. In some embodiments, the wafer 100 is a semiconductor wafer (eg, a Si wafer) having a diameter of 150 mm, 200 mm, or 300 mm. In some embodiments, one or more layers or features are formed on the semiconductor wafer 100 .

[0026] like Figure 2G As shown, the rotation speed of the wafer is changed at least four times during the dispensing of the photoresist. In some embodiments, the rotation speed of the wafer is changed five or six times during the dispensing of the photoresist. In some embodiments, the photoresist coating sequence includes six steps with different conditions. Step 0 is a pre-dispensing sequence, which includes steps corresponding to Figure 2A and step 7 is a post-assignment step, which also includes a step corresponding to Figure 2F In some embodiments, the wafer is treated with a resist primer material, such as hexamethyldisilazane (HMDS), to improve adhesion between the wafer surface and the photoresist.

[0027] In some embodiments, the pre-dispensing sequence includes applying a compound for resist reduction consumption, which is a pre-wet process for improving the surface condition of the wafer. In some embodiments, the compound includes a solvent for edge cutting operation and / or backside cleaning operation in the post-dispensing sequence. In some embodiments, the solvent is applied to the wafer for about 10 seconds to about 30 seconds at a wafer rotation speed of about 100 rpm to about 500 rpm. In some embodiments, after applying the solvent for resist reduction consumption, the wafer is rotated at about 100 rpm to about 500 rpm for about 0.5 seconds to about 2 seconds.

[0028] In some embodiments, at step 1, the dispensing of photoresist begins. In some embodiments, the wafer rotation speed S1 in step 1 is in the range of about 50 rpm to about 1000 rpm. In other embodiments, the wafer rotation speed S1 in step 1 is in the range of about 50 rpm to about 150 rpm. In some embodiments, the acceleration A1 from the speed S0 of the last step of the pre-dispensing sequence to the speed S1 is about 1000 rpm / sec.2 To about 30000rpm / sec 2 and in other embodiments, about 5000 rpm / sec 2 Up to 15000rpm / sec 2 In some embodiments, the duration T1 of step 1 is in the range of about 0.6 seconds to about 1.0 seconds, and in other embodiments, in the range of about 0.7 seconds to 0.9 seconds. In step S1, the dispensed photoresist forms a puddle on the wafer at a relatively low wafer rotation speed. In some embodiments, the nozzle position is at the center of the wafer.

[0029] In some embodiments, at step 2, the photoresist pits are spread over the wafer at a higher speed, which corresponds to Figure 2C In some embodiments, the wafer rotation speed S2 in step 2 is in the range of about 2500 rpm to about 4000 rpm. In other embodiments, the wafer rotation speed S2 in step 2 is in the range of about 3000 rpm to about 4000 rpm. In some embodiments, the acceleration A2 from the speed S1 in step 1 to the speed S2 is about 15000 rpm / sec. 2 To about 30000rpm / sec 2 In other embodiments, the speed is about 20,000 rpm / sec. 2 Up to 25000rpm / sec 2 The duration T2 of step 2 is less than T1, and in some embodiments is in the range of about 0.1 seconds to about 0.3 seconds, and in other embodiments is in the range of about 0.15 seconds to 0.25 seconds. In some embodiments, the nozzle position is at the center of the wafer.

[0030] In some embodiments, in step 3, the diffused photoresist is reflowed by reducing the speed. In some embodiments, the wafer rotation speed S3 in step 3 is lower than the speed S2 and higher than the speed S1, and is in the range of about 100 rpm to about 2500 rpm. In other embodiments, the wafer rotation speed S3 in step 3 is in the range of about 1500 rpm to about 1900 rpm. In some embodiments, the acceleration A3 from the speed S2 of step 2 to the speed S3 is about 1000 rpm / sec. 2 To about 30000rpm / sec 2 In the range of , and in other embodiments at about 5000 rpm / sec 2 Up to 15000rpm / sec 2In some embodiments, the duration T3 of step 3 is in the range of about 0.1 seconds to about 0.3 seconds, and in other embodiments in the range of about 0.15 seconds to 0.25 seconds. In some embodiments, the nozzle position is at the center of the wafer.

[0031] In some embodiments, in step 4, the thickness of the diffused photoresist is adjusted by increasing the speed. In some embodiments, the wafer rotation speed S4 in step 4 is higher than the speeds S3 and S1 and lower than the speed S2, and is in the range of about 1000 rpm to about 3000 rpm. In other embodiments, the wafer rotation speed S4 in step 4 is in the range of about 2000 rpm to about 2500 rpm. In some embodiments, the acceleration A4 from the speed S3 of step 3 to the speed S4 is about 10000 rpm / sec. 2 To about 30000rpm / sec 2 In the range of , and in other embodiments at about 15000 rpm / sec 2 Up to 25000rpm / sec 2 The duration T4 of step 4 is longer than T3, and in some embodiments is in the range of about 0.3 seconds to about 0.7 seconds, and in other embodiments is in the range of about 0.4 seconds to 0.6 seconds. In some embodiments, the nozzle position is at the center of the wafer.

[0032] In some embodiments, at step 5, the nozzle position is moved while dispensing to further adjust the thickness of the photoresist, which corresponds to Figure 2D . In some embodiments, in the case of a 300 mm wafer, the total nozzle movement distance M1 is in the range of about 1 mm to about 15 mm, and in other embodiments in the range of about 5 mm to about 10 mm. In some embodiments, the nozzle movement distance M1 is adjusted proportionally according to the diameter of the wafer. In some embodiments, the speed S15 of the nozzle movement is in the range of about 25 mm / sec to about 294 mm / sec, and in other embodiments in the range of about 100 mm / sec to about 200 mm / sec. When the nozzle moves faster or slower than the above range, the thickness variation of the applied photoresist increases and exceeds the desired variation.

[0033] In some embodiments, the wafer rotation speed S5 in step 5 is higher than speeds S3 and S1 and lower than speed S2, and is in the range of about 1000 rpm to about 3000 rpm. In other embodiments, the wafer rotation speed S5 in step 5 is in the range of about 2000 rpm to about 2500 rpm. In some embodiments, the acceleration A5 from speed S4 in step 4 to speed S5 is about 10000 rpm / sec. 2To about 30000rpm / sec 2 In the range of , and in other embodiments about 20000 rpm / sec 2 Up to 25000rpm / sec 2 In some embodiments, speed S5 is equal to speed S4, so acceleration A5 is zero. Duration T5 of step 5 is shorter than T4, and in some embodiments is in the range of about 0.1 seconds to about 0.3 seconds, and in other embodiments is in the range of about 0.15 seconds to 0.25 seconds. In some embodiments, nozzle motion begins and / or ends within duration T5.

[0034] In some embodiments, at step 6, the spread photoresist is reflowed by reducing the speed, such as Figure 2E As shown. In some embodiments, the wafer rotation speed S6 in step 6 is lower than speeds S4 and S5 and higher than speed S1, and is in the range of about 500 rpm to about 2500 rpm. In other embodiments, the wafer rotation speed S6 in step 6 is in the range of about 500 rpm to about 1500 rpm. In some embodiments, the acceleration A6 from speed S5 in step 5 to speed S6 is about 1000 rpm / sec. 2 To about 30000rpm / sec 2 In the range of , and in other embodiments at about 5000 rpm / sec 2 Up to 15000rpm / sec 2 The duration T6 of step 6 is longer than T5, and in some embodiments is in the range of about 0.3 seconds to about 0.7 seconds, and in other embodiments is in the range of about 0.4 seconds to 0.6 seconds. In some embodiments, the nozzle position is at the shifted position. In some embodiments, during or at the end of step 6, the resist dispensing stops. In some embodiments, the dispensing stops about 0.08 seconds to 0.12 seconds after the start of step 6.

[0035] After step 6, the post-allocation sequence step 7 is executed, such as Figure 2F As shown. The post-dispensing sequence includes various steps, such as a dry spin, an edge cutting operation (for removing the applied photoresist at the edge (e.g., 3-5 mm) of the wafer), and a backside rinsing operation (for cleaning the back side of the wafer 100). The rotation speed S7 in step 7 of the post-dispensing sequence varies depending on the operation and in some embodiments is in the range of about 500 rpm to 1500 rpm. In some embodiments, the acceleration A7 from the speed S6 of step 6 to the speed S7 is about 1000 rpm / sec. 2 To about 30000rpm / sec 2In the range of , and in other embodiments at about 5000 rpm / sec 2 Up to 15000rpm / sec 2 within the range.

[0036] In the foregoing embodiments, in some embodiments, the pump supplies photoresist at a rate of about 0.1cc / sec to about 0.3cc / sec, and in other embodiments, the rate is about 0.15cc / sec to about 0.25cc / sec. In some embodiments, the total amount of photoresist dispensed is in the range of about 0.35cc to about 0.6cc, and in other embodiments in the range of about 0.4cc to 0.5cc. The above sequence is adjusted according to the viscosity of the photoresist. The total amount of dispensed can be adjusted by adjusting one or more of the durations in steps 1-6 and / or by adjusting the pump speed.

[0037] In some embodiments, the photoresist is an EUV photoresist, a DUV photoresist, a UV photoresist, or an electron beam photoresist. The photoresist according to the present disclosure is a chemically amplified resist, which includes a polymer resin, a photosensitive compound (PAC) and a solvent. In some embodiments, the polymer resin includes a hydrocarbon structure (e.g., an alicyclic hydrocarbon structure) containing one or more groups, which will decompose (e.g., an acid-labile group) or react in other ways when mixed with an acid, a base or a free radical produced by PAC (as described below). In some embodiments, the hydrocarbon structure includes a repeating unit forming the skeleton backbone of the polymer resin. The repeating unit may include acrylates, methacrylates, crotonates, vinyl esters, maleic diesters, fumaric diesters, itaconic diesters, (meth) acrylonitrile, (meth) acrylamide, styrene, vinyl ether, combinations thereof, etc. In some embodiments, the repeating unit of the hydrocarbon structure also has a monocyclic or polycyclic hydrocarbon structure substituted therein, or the monocyclic or polycyclic hydrocarbon structure is a repeating unit so as to form an alicyclic hydrocarbon structure.

[0038] PACs are photosensitive components, such as photoacid generators, photobase generators, free radical generators, etc. PACs can be positive-acting or negative-acting. In some embodiments where the PAC is a photoacid generator, the PAC includes halogenated triazines, onium salts, diazonium salts, aromatic diazonium salts, phosphonium salts, sulfonium salts, iodonium salts, imide sulfonates, oxime sulfonates, diazodisulfones, disulfones, o-nitrobenzylsulfonates, sulfonates, halogenated sulfonyloxy dicarboximides, diazodisulfones, α-cyanooxyamine-sulfonates, imide sulfonates, ketodiazosulfones, sulfonyldiazoesters, 1,2-di(arylsulfonyl)hydrazines, nitrobenzyl esters, and s-triazine derivatives, combinations of these, and the like. In some embodiments where the PAC is a photobase generator, the PAC includes quaternary ammonium dithiocarbamates, alpha aminoketones, oxime-carbamate-containing molecules (such as dibenzophenoneoximehexamethylene diurethan), ammonium tetraorganylborate salts, and N-(2-nitrobenzyloxycarbonyl)cyclic amines, combinations of these, and the like.

[0039] In some embodiments, a cross-linking agent is added to the photoresist. The cross-linking agent reacts with a group of one of the hydrocarbon structures in the polymer resin, and also reacts with a second group of another hydrocarbon structure to cross-link and bond the two hydrocarbon structures together. This bonding and cross-linking increases the molecular weight of the polymer product of the cross-linking reaction and increases the total connection density of the photoresist. This increase in density and connection density helps to improve the resist pattern.

[0040] In some embodiments, a quencher is added to the photoresist. The quencher inhibits the diffusion of the generated acid / base / radicals within the photoresist. The quencher improves the resist pattern configuration and the stability of the photoresist over time.

[0041] In some embodiments, an organometallic compound is added to the photoresist to increase the absorption of EUV. In some embodiments, the organometallic compound includes one or more metal oxide nanoparticles selected from the group consisting of titanium dioxide, zinc oxide, zirconium dioxide, nickel oxide, cobalt oxide, manganese oxide, copper oxide, iron oxide, strontium titanate, tungsten oxide, vanadium oxide, chromium oxide, tin oxide, hafnium oxide, indium oxide, cadmium oxide, molybdenum oxide, tantalum oxide, niobium oxide, aluminum oxide, and combinations thereof. As used herein, nanoparticles are particles having an average particle size between about 1 nm and about 20 nm. In some embodiments, the metal oxide nanoparticles have an average particle size between about 2 nm and about 5 nm. In some embodiments, the amount of metal oxide nanoparticles in the photoresist composition is in the range of about 1 wt.% to about 15 wt.%, based on the weight of the solvent. In some embodiments, the amount of nanoparticles in the photoresist composition is in the range of about 5 wt.% to about 10 wt.%, based on the weight of the solvent.

[0042] In some embodiments, the solvent is one or more selected from the following: propylene glycol methyl ether acetate (PGMEA), propylene glycol monomethyl ether (PGME), 1-ethoxy-2-propanol (PGEE), γ-butyrolactone (GBL), cyclohexanone (CHN), ethyl lactate (EL), methanol, ethanol, propanol, n-butanol, acetone, dimethylformamide (DMF), isopropanol (IPA), tetrahydrofuran (THF), methyl isobutyl carbinol (MIBC), n-butyl acetate (nBA), and 2-heptanone (MAK).

[0043] In some embodiments, the viscosity of the photoresist is adjusted to a range of about 1.0 centipoise (mPa·s) to about 2.5 centipoise. When the viscosity of the photoresist is high, the total dispense amount is set higher. In some embodiments, depending on the process requirements (e.g., dry etching selectivity), the thickness of the photoresist is in the range of about 20nm to about 500nm, and in the range of about 30nm to about 120nm. The thickness can be adjusted by adjusting one or more of the following items: rotation speed, duration in steps 1-6, total dispense amount, nozzle movement speed in step 5, and / or nozzle movement amount. In some embodiments, the nozzle movement amount is set longer (e.g., 8mm to 12mm) to obtain a resist thickness equal to or greater than 100nm. In some embodiments, the nozzle movement amount is set shorter (e.g., 4mm to 6mm) to obtain a resist thickness less than 100nm. In some embodiments, the rotation speed of step 2 is set lower (e.g., 2800rpm to 3200rpm) to obtain a resist thickness equal to or greater than 100nm. In some embodiments, the spin speed of step 2 is set higher (eg, 3300 rpm to 3700 rpm) to obtain a resist thickness of less than 100 nm.

[0044] Figure 3 1 shows the effect of nozzle tip height according to an embodiment of the present disclosure. In some embodiments, during dispensing, the nozzle tip (dispensing opening) of nozzle 120 is set at a height H1 from the surface of wafer 100. In some embodiments, height H1 is in the range of about 2.0 mm to about 4.0 mm, and in other embodiments in the range of about 2.5 mm to about 3.5 mm.

[0045] The lower height of the nozzle tip can reduce the resist dispensing momentum, which prevents the resist from splashing on the wafer and enables continuous dispensing rather than droplets. Specifically, when the wafer rotation speed of step 1 is low, the lower height of the nozzle tip is more effective in preventing resist splashing. When the height is less than the disclosed range, the smooth dispensing of the photoresist is impaired, which will result in uneven resist thickness. When the height is greater than these ranges, resist splashing may occur.

[0046] Figure 4A is a schematic diagram of a resist dispensing nozzle 120 according to an embodiment of the present disclosure. In some embodiments, the end opening of the nozzle has a circular shape, such as Figure 4CAs shown, the diameter D1 (inner diameter) is in the range of about 0.4 mm to about 0.6 mm. In other embodiments, the diameter is in the range of about 0.45 mm to about 0.55 mm. When the diameter is less than these ranges, the smooth distribution of the photoresist is impaired, which will result in uneven resist thickness. When the diameter is greater than these ranges, the resist consumption is large and the cost of photoresist operation per wafer increases.

[0047] In some embodiments, Figure 4A As shown, the inner diameter of the nozzle 120 is constant within a certain distance L2 from the tip, for example, at least about 0.5 cm to about 3 cm. In other embodiments, the inner diameter of the nozzle decreases from the diameter D2 toward the tip, such as Figure 4B In some embodiments, the diameter D2 is in the range of about 1 mm to about 3 mm. In some embodiments, the nozzle has a tapered shape (interior) that reduces the diameter from D2 to D1 at a constant rate. In some embodiments, the tapered portion L2 is in the range of about 0.5 cm to about 3 cm. The ratio of the height H1 to the diameter D2 is in the range of about 3.3 to about 10.

[0048] In some embodiments, the shape of the end opening of the nozzle 120 is elliptical, such as Figure 4C As shown, in this case, the diameter D1 is the average of the short diameter (minor axis) and the long diameter (major axis) of the ellipse.

[0049] In some embodiments, the nozzle 120 is tilted relative to the normal direction of the wafer 100, such as Figure 5A In some embodiments, the tilt angle θ1 is greater than zero and equal to or less than about 10 degrees. Figure 5B and Figure 5C As shown, the nozzle 120 is tilted in the rotation direction (tangential direction of rotation) at the shift position so that the resist dispensing direction is consistent with the wafer rotation direction. Figure 5B and Figure 5C As shown, when the nozzle 120 is tilted, the nozzle moves in step 5 so that the angle between the resist dispensing direction and the rotation direction does not change. In other embodiments, during the movement of the nozzle in step 5, the angle between the resist dispensing direction and the rotation direction changes.

[0050] In some embodiments, the tilt angle θ1 is fixed during the resist dispensing. In other embodiments, the tilt angle θ1 varies during the resist dispensing. In some embodiments, the tilt angle changes at the beginning, during, or end of the movement of the nozzle in step 5. In some embodiments, before step 5 (steps 1-4), the tilt angle θ1 is set to zero degrees, and in step 5, the tilt angle θ1 is set to be greater than zero degrees. In some embodiments, the tilt angle θ1 changes gradually in step 5, and in other embodiments, the tilt angle θ1 changes in a step-wise manner. In some embodiments, when the opening shape of the nozzle has a shape such as Figure 4B The ellipse is shown with the major axis parallel to the wafer 100 .

[0051] Fig. 6A and Figure 6B The effect of nozzle height is shown. For three different target thicknesses (36nm, 40nm and 43nm), Fig. 6A The resist thickness variation when the nozzle tip opening size is 0.8 mm and the nozzle height is 5 mm is shown. Figure 6B The resist thickness variation is shown when the nozzle tip opening size is 0.5 mm and the nozzle height is 3 mm. Fifty-five (55) points were measured on a 300 mm Si wafer (bare Si). Fig. 6A and Figure 6B As shown, by reducing the nozzle tip opening size and the nozzle height from the wafer surface, the uniformity of the resist thickness is improved by about 17% to about 27%.

[0052] Typically, the resist dispense amount for a 300 mm wafer is about 0.6 cc to about 1.5 cc, depending on the type of photoresist (eg, viscosity). By using the foregoing embodiments, the resist dispense amount can be reduced by about 20% to about 75%.

[0053] Fig. 7A and Figure 7B The effect of reducing the amount of resist dispensed according to an embodiment of the present disclosure is shown. Fig. 7A and Figure 7B In , the resist thickness applied on 300 mm bare Si wafers was measured at 225 points for 8 wafers by varying the total resist dispense amount per wafer. Fig. 7A and Figure 7B In the experiment, the nozzle height was set to 3 mm and the diameter of the nozzle end opening was 0.5 mm.

[0054] exist Fig. 7AIn the embodiment of the present invention, the viscosity of the photoresist is 1.5 centipoise. Although the photoresist cannot be uniformly coated with a dispense amount of 0.3 cc, it can be uniformly coated with a dispense amount of 0.4 cc or more. For a target thickness of 100 nm, the variation of the resist thickness for the 0.5 cc case is about 1.1 nm to about 1.4 nm.

[0055] exist Figure 7B In the example, the viscosity of the photoresist is 2.445 centipoise. Although the photoresist cannot be uniformly coated with a 0.4cc dispense amount, it can be uniformly coated with a 0.5cc or larger dispense amount. For a target thickness of 20nm, the variation in resist thickness for the 0.6cc case is about 0.6nm to about 0.7nm.

[0056] When the resist coating recipe includes three steps (dispensing photoresist at a low speed (e.g., 200-300 rpm), dispensing photoresist at a high speed (e.g., 3000-3500 rpm) while continuously dispensing photoresist, and reflowing photoresist at a low speed (e.g., 500-1000 rpm) while continuously dispensing photoresist), the amount of photoresist dispensed is about 0.7 cc to obtain the desired thickness variation of less than 1 nm. In contrast, using the recipe of the aforementioned embodiment, the amount of resist dispensed can be reduced to 0.4-0.6 cc.

[0057] It will be understood that not all advantages have necessarily been discussed herein, that a particular advantage is not required for all embodiments or examples, and that other embodiments or examples may provide different advantages.

[0058] For example, according to one or more of the foregoing embodiments, the amount of resist dispensed is reduced to 0.4-0.6cc per 300mm wafer, and the thickness variation (range) is less than 1.5nm (greater than zero) or less than 1nm, which is more than 15% less than the conventional resist coating method. This significantly reduces the cost of the photolithography process by more than $10 million per year.

[0059] According to one aspect of the present disclosure, in a method of coating photoresist on a wafer, dispensing photoresist on the wafer from a nozzle begins while the wafer is rotating, and dispensing photoresist stops while the wafer is rotating. After dispensing photoresist begins and before dispensing photoresist stops, the wafer rotation speed changes at least 4 times. In one or more of the foregoing or following embodiments, photoresist is dispensed while the wafer is rotating at a first speed, dispensing photoresist continues while the wafer is rotating at a second speed different from the first speed, dispensing photoresist continues while the wafer is rotating at a third speed different from the second speed, dispensing photoresist continues while the wafer is rotating at a fourth speed different from the third speed, dispensing photoresist continues while the wafer is rotating at a fifth speed, and dispensing photoresist stops while the wafer is rotating at a sixth speed different from the fifth speed. In one or more of the foregoing or following embodiments, the first speed is lower than the second to sixth speeds. In one or more of the foregoing or following embodiments, the second speed is higher than the first speed and the third to sixth speeds. In one or more of the foregoing or following embodiments, the third speed is lower than the second speed. In one or more of the foregoing or following embodiments, the fourth speed and the fifth speed are higher than the third speed. In one or more of the foregoing or following embodiments, the sixth speed is lower than the fifth speed. In one or more of the foregoing or following embodiments, the fourth speed is equal to the fifth speed. In one or more of the foregoing or following embodiments, the total dispensed amount of the photoresist is in the range of 0.35cc to 0.65cc. In one or more of the foregoing or following embodiments, the tip of the nozzle is located at a height of 2.5mm to 3.5mm from the wafer. In one or more of the foregoing or following embodiments, the nozzle is tilted relative to the normal of the wafer.

[0060] According to another aspect of the present disclosure, in a method of coating a photoresist on a wafer, dispensing of photoresist from a nozzle begins while the wafer is rotated at a first speed, dispensing of photoresist continues for a duration T2 while the wafer is rotated at a second speed different from the first speed, dispensing of photoresist continues for a duration T3 while the wafer is rotated at a third speed different from the second speed, dispensing of photoresist continues for a duration T4 while the wafer is rotated at a fourth speed different from the third speed, dispensing of photoresist continues while the wafer is rotated at a fifth speed and the nozzle is horizontally moved from the center of the wafer to the edge of the wafer, and after stopping the movement of the nozzle, dispensing of photoresist stops while the wafer is rotated at a sixth speed different from the fifth speed. In one or more of the foregoing or following embodiments, the nozzle moves at a speed in the range of 25 mm / sec to 294 mm / sec. In one or more of the foregoing or following embodiments, the nozzle moves a distance of 1 mm to 15 mm. In one or more of the foregoing or following embodiments, the duration T1 of changing from the first speed to the second speed after starting to dispense the photoresist is in the range of 0.6sec to 1.0sec, T2 and T3 are shorter than T1 and T4, and the duration T5 of moving the nozzle is in the range of 0.15sec to 0.25sec. In one or more of the foregoing or following embodiments, the tip of the nozzle is located at a height of 2.5mm to 3.5mm from the wafer. In one or more of the foregoing or following embodiments, the nozzle is tilted relative to the normal of the wafer. In one or more of the foregoing or following embodiments, the first speed is in the range of 100rpm to 1000rpm, the second speed is in the range of 2000rpm to 4000rpm, the third speed is in the range of 1500rpm to 1900rpm, the fourth speed is in the range of 1000rpm to 3000rpm, and the sixth speed is in the range of 500rpm to 1000rpm. In one or more of the foregoing or following embodiments, the average thickness of the applied photoresist is T0, and the thickness variation of the applied photoresist is within a range of 1% to 2% of T0.

[0061] According to another aspect of the present disclosure, a photoresist coating device includes: a wafer holder configured to support a wafer and rotate the wafer; a nozzle configured to dispense photoresist; an arm coupled to the nozzle and configured to move the nozzle horizontally and vertically; and a control system including a processor and a memory storing a program and a coating recipe, and configured to control the wafer holder, the nozzle, and the arm according to the coating recipe. The program, when executed by the processor, causes the control system to perform the following operations: start dispensing photoresist from the nozzle when the wafer is rotated at a first speed, continue dispensing photoresist when the wafer is rotated at a second speed different from the first speed, continue dispensing photoresist when the wafer is rotated at a third speed different from the second speed, continue dispensing photoresist when the wafer is rotated at a fourth speed different from the third speed, continue dispensing photoresist when the wafer is rotated at a fifth speed, and stop dispensing photoresist when the wafer is rotated at a sixth speed different from the fifth speed after stopping the movement of the nozzle. In one or more of the foregoing or following embodiments, continuously dispensing the photoresist while rotating the wafer at the fifth speed includes horizontally moving the nozzle from a center of the wafer toward an edge of the wafer.

[0062] 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 should understand that they can easily use the present disclosure as a basis for designing or modifying other processes and structures to achieve the same purpose of the embodiments or examples introduced herein and / or achieve the same advantages of the embodiments or examples introduced herein. Those skilled in the art should also recognize that such equivalent constructions do not depart from the spirit and scope of the present disclosure, and they can make various changes, substitutions and modifications herein without departing from the spirit and scope of the present disclosure.

[0063] Example 1. A method for coating photoresist onto a wafer, comprising: starting to dispense the photoresist onto the wafer from a nozzle while rotating the wafer; stopping dispensing the photoresist while rotating the wafer; and changing the wafer rotation speed at least 4 times after starting to dispense the photoresist and before stopping to dispense the photoresist.

[0064] Example 2. The method according to Example 1 includes: dispensing the photoresist while the wafer is rotated at a first speed; continuously dispensing the photoresist while the wafer is rotated at a second speed different from the first speed; continuously dispensing the photoresist while the wafer is rotated at a third speed different from the second speed; continuously dispensing the photoresist while the wafer is rotated at a fourth speed different from the third speed; continuously dispensing the photoresist while the wafer is rotated at a fifth speed; and stopping dispensing the photoresist while the wafer is rotated at a sixth speed different from the fifth speed.

[0065] Example 3. The method of Example 2, wherein the first speed is lower than the second to sixth speeds.

[0066] Example 4. The method of Example 3, wherein the second speed is higher than the first speed and the third to sixth speeds.

[0067] Example 5. The method of Example 4, wherein the fourth speed and the fifth speed are higher than the third speed.

[0068] Example 6. The method of Example 5, wherein the sixth speed is lower than the fifth speed.

[0069] Example 7. The method of Example 5, wherein the fourth speed is equal to the fifth speed.

[0070] Example 8. The method of example 1, wherein the total dispensed amount of the photoresist is in a range of 0.35 cc to 0.65 cc.

[0071] Example 9. The method of Example 1, wherein the tip of the nozzle is located at a height of 2.5 mm to 3.5 mm from the wafer.

[0072] Example 10. The method of Example 1, wherein the nozzle is tilted relative to a normal to the wafer.

[0073] Example 11. A method for coating photoresist on a wafer, comprising: starting to dispense the photoresist from a nozzle while rotating the wafer at a first speed; continuously dispensing the photoresist for a second duration T2 while rotating the wafer at a second speed different from the first speed; continuously dispensing the photoresist for a third duration T3 while rotating the wafer at a third speed different from the second speed; continuously dispensing the photoresist for a fourth duration T4 while rotating the wafer at a fourth speed different from the third speed; continuously dispensing the photoresist while rotating the wafer at a fifth speed and horizontally moving the nozzle from the center of the wafer to the edge of the wafer; and after stopping the movement of the nozzle, stopping dispensing the photoresist while rotating the wafer at a sixth speed different from the fifth speed.

[0074] Example 12. The method of Example 11, wherein the nozzle moves at a speed in the range of 25 mm / sec to 294 mm / sec.

[0075] Example 13. The method of Example 11, wherein the nozzle moves a distance of 1 mm to 15 mm.

[0076] Example 14. A method according to Example 11, wherein: a first duration T1 of changing from the first speed to the second speed after starting to dispense the photoresist is in the range of 0.6 sec to 1.0 sec, the second duration T2 and the third duration T3 are shorter than the first duration T1 and the fourth duration T4, and a fifth duration T5 of moving the nozzle is in the range of 0.15 sec to 0.25 sec.

[0077] Example 15. The method of Example 11, wherein the tip of the nozzle is located at a height of 2.5 mm to 3.5 mm from the wafer.

[0078] Example 16. The method of Example 11, wherein the nozzle is tilted relative to a normal to the wafer.

[0079] Example 17. A method according to Example 11, wherein: the first speed is in the range of 100rpm to 1000rpm, the second speed is in the range of 2000rpm to 4000rpm, the third speed is in the range of 1500rpm to 1900rpm, the fourth speed is in the range of 1000rpm to 3000rpm, and the sixth speed is in the range of 500rpm to 1000rpm.

[0080] Example 18. The method of Example 11, wherein: an average thickness of the applied photoresist is T0, and a thickness variation of the applied photoresist is within a range of 1% to 2% of T0.

[0081] Example 19. A photoresist coating device, comprising: a wafer holder configured to support a wafer and rotate the wafer; a nozzle configured to dispense photoresist; an arm coupled to the nozzle and configured to move the nozzle horizontally and vertically; and a control system comprising a processor and a memory storing a program and a coating recipe, and configured to control the wafer holder, the nozzle and the arm according to the coating recipe, wherein: the program, when executed by the processor, causes the control system to perform the following operations: start dispensing the photoresist from the nozzle while rotating the wafer at a first speed ; continuously dispensing the photoresist while rotating the wafer at a second speed different from the first speed; continuously dispensing the photoresist while rotating the wafer at a third speed different from the second speed; continuously dispensing the photoresist while rotating the wafer at a fourth speed different from the third speed; continuously dispensing the photoresist while rotating the wafer at a fifth speed and horizontally moving the nozzle from the center of the wafer to the edge of the wafer; and after stopping the movement of the nozzle, stopping dispensing the photoresist while rotating the wafer at a sixth speed different from the fifth speed.

[0082] Example 20. The photoresist coating apparatus of Example 19, wherein continuously dispensing the photoresist while rotating the wafer at the fifth speed comprises horizontally moving a nozzle from a center of the wafer toward an edge of the wafer.

Claims

1. A method for coating a photoresist on a wafer, comprising: beginning to dispense the photoresist from a nozzle over the wafer while rotating the wafer; stopping dispensing the photoresist while rotating the wafer; as well as changing a wafer rotation speed at least 4 times after starting to dispense the photoresist and before stopping to dispense the photoresist; Wherein, dispensing the photoresist comprises: dispensing the photoresist while rotating the wafer at a first speed; continuously dispensing the photoresist while rotating the wafer at a second speed greater than the first speed; continuously dispensing the photoresist while rotating the wafer at a third speed that is lower than the second speed and higher than the first speed; continuously dispensing the photoresist while rotating the wafer at a fourth speed that is higher than the first speed and the third speed and lower than the second speed; continuously dispensing the photoresist while rotating the wafer at a fifth speed that is higher than the first speed and the third speed and lower than the second speed and horizontally moving the nozzle from the center of the wafer toward the edge of the wafer; and The dispensing of the photoresist is stopped while the wafer is rotated at a sixth speed that is higher than the first speed and lower than the fourth speed and the fifth speed.

2. The method according to claim 1, wherein: The first speed is lower than the second to sixth speeds.

3. The method according to claim 2, wherein: The second speed is higher than the first speed and the third to sixth speeds.

4. The method according to claim 3, wherein: The fourth speed and the fifth speed are higher than the third speed.

5. The method according to claim 4, wherein: The sixth speed is lower than the fifth speed.

6. The method according to claim 4, wherein: The fourth speed is equal to the fifth speed.

7. The method according to claim 1, wherein: The total dispensed amount of the photoresist is in the range of 0.35 cc to 0.65 cc.

8. The method according to claim 1, wherein: The tip of the nozzle is located at a height of 2.5 mm to 3.5 mm from the wafer.

9. The method according to claim 1, wherein: The nozzle is tilted relative to a normal to the wafer.

10. A method for coating a photoresist on a wafer, comprising: beginning dispensing the photoresist from a nozzle while rotating the wafer at a first speed; continuing to dispense the photoresist for a second duration T2 while rotating the wafer at a second speed higher than the first speed; continuing to dispense the photoresist for a third duration T3 while rotating the wafer at a third speed that is lower than the second speed and higher than the first speed; continuing to dispense the photoresist for a fourth duration T4 while rotating the wafer at a fourth speed that is higher than the first speed and the third speed and lower than the second speed; continuously dispensing the photoresist while rotating the wafer at a fifth speed that is higher than the first speed and the third speed and lower than the second speed and horizontally moving the nozzle from the center of the wafer toward the edge of the wafer; as well as After stopping the movement of the nozzle, dispensing of the photoresist is stopped while rotating the wafer at a sixth speed that is higher than the first speed and lower than the fourth speed and the fifth speed.

11. The method according to claim 10, wherein: The nozzle moves at a speed in the range of 25 mm / sec to 294 mm / sec.

12. The method according to claim 10, wherein: The nozzle moves a distance of 1 mm to 15 mm.

13. The method of claim 10, wherein: A first duration T1 of changing from the first speed to the second speed after starting to dispense the photoresist is in the range of 0.6 sec to 1.0 sec, The second duration T2 and the third duration T3 are shorter than the first duration T1 and the fourth duration T4, and The fifth duration T5 for moving the nozzle is in the range of 0.15 sec to 0.25 sec.

14. The method according to claim 10, wherein: The tip of the nozzle is located at a height of 2.5 mm to 3.5 mm from the wafer.

15. The method according to claim 10, wherein: The nozzle is tilted relative to a normal to the wafer.

16. The method of claim 10, wherein: The first speed is in the range of 100 rpm to 1000 rpm, The second speed is in the range of 2000 rpm to 4000 rpm, The third speed is in the range of 1500 rpm to 1900 rpm, The fourth speed is in the range of 1000 rpm to 3000 rpm, and The sixth speed is within the range of 500 rpm to 1000 rpm.

17. The method of claim 10, wherein: The average thickness of the applied photoresist is T0, and The thickness variation of the applied photoresist is in the range of 1% to 2% of T0.

18. A photoresist coating device, comprising: a wafer holder configured to support a wafer and rotate the wafer; a nozzle configured to dispense photoresist; an arm coupled to the nozzle and configured to move the nozzle horizontally and vertically; as well as a control system comprising a processor and a memory storing a program and a coating recipe, and configured to control the wafer holder, the nozzle and the arm according to the coating recipe, wherein: The program, when executed by the processor, causes the control system to perform the following operations: beginning dispensing the photoresist from the nozzle while rotating the wafer at a first speed; continuously dispensing the photoresist while rotating the wafer at a second speed greater than the first speed; continuously dispensing the photoresist while rotating the wafer at a third speed that is lower than the second speed and higher than the first speed; continuously dispensing the photoresist while rotating the wafer at a fourth speed that is higher than the first speed and the third speed and lower than the second speed; continuously dispensing the photoresist while rotating the wafer at a fifth speed that is higher than the first speed and the third speed and lower than the second speed and horizontally moving the nozzle from the center of the wafer toward the edge of the wafer; and After stopping the movement of the nozzle, dispensing of the photoresist is stopped while rotating the wafer at a sixth speed that is higher than the first speed and lower than the fourth speed and the fifth speed.

19. The photoresist coating apparatus according to claim 18, wherein: Continuously dispensing the photoresist while rotating the wafer at the fifth speed includes horizontally moving a nozzle from a center of the wafer toward an edge of the wafer.

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