A method for reducing metal residue in the edge bead region from metal-containing resists.

Abstract

The present invention provides a method for removing edge beads on a wafer associated with a resist coating containing a metal-containing resist composition. [Solution] In a corresponding apparatus for processing a wafer, the method comprises the step of spin-coating a wafer 150 with a metal-based resist composition 158, and then applying a first bead edge rinse solution along the wafer edge. The edge bead solution comprises an organic solvent and an additive comprising a carboxylic acid, an inorganic fluorinated acid, a tetraalkylammonium compound, or a mixture thereof. Alternatively or in addition, the method comprises the step of applying a protective composition 154 to the wafer 150 before performing the edge bead rinse. The protective composition is a sacrificial material or an anti-adhesion material and is applied only to the wafer edge, or, in the case of a protective composition, over the entire wafer.

Description

[Technical Field]

[0001] Cross-reference of related applications This application claims priority to the concurrently contested U.S. Provisional Patent Application No. 62 / 374,582, titled "Bead Washing for Metal Oxide Based Resists," filed August 12, 2016, and to the concurrently contested U.S. Provisional Patent Application No. 62 / 430,722, titled "Method of Reducing Metal Residue in Edge Bead Region from Metal-Containing Resists," filed December 6, 2016, both of which are incorporated herein by reference.

[0002] The present invention relates to a process for reducing metal contamination along wafer edges that can potentially arise from the use of metal-based patterning resists. [Background technology]

[0003] The fabrication of semiconductor circuits and devices has been accompanied by a continuous reduction in critical dimensions across each generation. As these dimensions shrink, new materials and methods are needed to meet the demand for fabricating and patterning increasingly smaller features. Patterning generally involves selectively exposing thin layers of radiosensitive material (resist) to form patterns that are then transferred to subsequent layers or functional materials. A promising new class of metal-based radioresists has been discovered that are particularly well-suited to providing good absorption of extreme ultraviolet and electron beam radiation, while simultaneously offering very high etching contrast. To bring these new classes of resists into practical use, considering process integration to realize the desired end product may be an important step. [Overview of the Initiative] [Means for solving the problem]

[0004] In a first aspect, the present invention relates to a method for removing edge beads on a wafer associated with a resist coating comprising a resist composition containing a metal, the method comprising the steps of spin-coating the wafer with the resist composition and then applying a first bead edge rinse solution along the wafer edge. In some embodiments, the edge bead solution comprises an organic solvent and an additive comprising a carboxylic acid, an inorganic fluorinated acid, a tetraalkylammonium compound, or a mixture thereof.

[0005] In a further embodiment, the present invention relates to a method for preparing a wafer for radiation-based patterning, comprising the steps of: coating a protective composition onto the wafer; spin-coating a resist composition containing a metal after coating the protective composition; and performing edge beading by applying an edge beading solution along the edge of the wafer after spin-coating the resist composition.

[0006] In other embodiments, the present invention relates to an apparatus comprising a spindle including a wafer support, a dispenser having a nozzle configured to deposit fluid along the edge of a wafer mounted on the spindle, and a fluid reservoir configured to deliver the fluid to the nozzle for distribution. Generally, the spindle is operably connected to a motor configured to rotate the spindle. In some embodiments, the fluid comprises an organic solvent with additives including a surface modifier, an acidic compound, a tetraalkylammonium compound, or a mixture thereof. [Brief explanation of the drawing]

[0007] [Figure 1] This is a schematic perspective view of an edge bead rinsing apparatus, showing the wafer position for processing to perform edge bead rinsing. [Figure 2] This is a schematic diagram illustrating the steps for preparing a wafer with a resist layer after edge bead rinsing, showing two processing steps. [Figure 3] This is a microscope image showing the wafer edge after edge bead rinsing. [Figure 4] This is a schematic diagram illustrating the steps used to form a sacrificial layer on the substrate, which is then used to facilitate the removal of edge beads in the rinsing step. Inset A shows a top view of the wafer after the final rinsing. [Figure 5] These are schematic diagrams illustrating steps used to form a sacrificial edge coating or sacrificial ring on a substrate to facilitate the removal of edge beads. Inset A is a top view of a wafer with a sacrificial ring, and inset B shows the final structure with the bead edges rinsed. [Figure 6] This schematic diagram illustrates a process using an anti-adhesion edge coating to substantially avoid resist deposition along the edges and a bead edge rinse to further reduce residual metal contamination along the edges after processing. Inset A shows a top view of a wafer with the anti-adhesion edge coating, inset B shows a top view of the structure after resist deposition, and inset C shows a top view of the structure after edge bead rinsing. [Modes for carrying out the invention]

[0008] Edge bead removal processes have been developed to more effectively remove metal and organometallic resist materials and residues. Substrate edge resist deposition can be removed before radiation patterning to reduce contamination of process equipment by the resist material. Edge bead removal solutions designed for conventional organic photoresists may not be sufficiently effective in removing metal-containing resists. Improved edge bead removal solutions may use selected solvents and may further contain additives such as acids to facilitate the removal of resist deposition. In additional or alternative embodiments, a sacrificial layer, such as a polymer layer, may be placed on the wafer edge or across the entire wafer surface to facilitate the removal of resist from the bead edge. Furthermore, an anti-adhesion layer, such as a coating with a sufficiently low critical surface tension, can be placed along the substrate edge to reduce or eliminate initial adhesion of resist along the substrate edge. Given the improved patterning performance of metal-based resists, particularly for fine patterning using extreme ultraviolet (EUV) light, it is advantageous to provide processing methods that can effectively incorporate metal-based resists into patterning processes using corresponding high-performance equipment. Therefore, the processes and corresponding compositions described herein greatly contribute to the practical application of metal-based resists. Where used herein, substrates and wafers are interchangeable to refer to structures that are generally, but always, cylindrical in shape and typically have a small thickness relative to their planar extent, unless otherwise specified.

[0009] Novel rinsing solutions have been identified for processing wafers coated with metal-based or metal-containing patterning resists to aid in edge bead removal. Metal-containing resist compositions can generally be considered to contain metal in excess of the amount of contaminants, e.g., at least 0.1 weight percent of metal, and several metal-containing resists of particular interest are described further below. For fine patterning of semiconductors and other radiation-based lithography processes, patterning resists are generally spin-coated onto wafers to form a relatively uniform resist layer over most of the wafer surface. Spin coating can result in beads along the wafer edges where the resist is deposited, relative to the resist layer covering most of the wafer, even if some of the excess resist spins off from the wafer surface. Since the edges themselves are not patterned using lithography, it is generally desirable to remove edge beads to facilitate wafer processing for patterning and reduce contamination. Novel rinsing compositions for effectively removing edge beads from metal-based or metal-containing resists may contain suitable organic solvents and additives, e.g., carboxylic acids, inorganic fluorinated acids, tetraalkylammonium fluoride containing strong acids, or combinations thereof. Removing edge beads from metal-based or metal-containing resists can also help reduce undesirable residual metal after the patterning process. After bead edge rinsing, wafer patterning generally continues using the usual steps for resist-based patterning.

[0010] During photoresist processing, an edge bead removal (EBR) rinsing step is commonly used. EBR processing is typically performed before any heat treatment or baking after photoresist deposition and involves rinsing the periphery of the wafer or substrate with a solvent to remove photoresist in selected areas. This EBR processing serves to reduce contamination of tools and machinery used to handle or manipulate the wafer or substrate. It is desirable to use metal-based photoresists to reduce the amount of residual metal, such as tin, in the EBR area. Standard EBR solvents based on organic solvents designed to remove polymer resists may not be as effective on their own to the desired extent in reducing the concentration of residual metal, such as tin, on the edge areas of the wafer surface to the desired level. In addition, the methods and materials described herein may be advantageous for processing resists containing a wide range of different metals, such as Hf, Zr, In, Te, Sb, Ni, Co, Ti, W, Ta, Mo, and combinations thereof, and this disclosure intends for such use.

[0011] A new class of radiation-based resists may be derived from metal oxide chemistry (metal oxo / hydroxo compositions) that utilizes radiation-sensitive ligands to control the stability and processability of the resist. A first set of new radiation-based resists utilizes peroxo ligands as radiation-sensitive stabilizing ligands. Peroxo-based metal oxo-hydroxo compounds are described, for example, in U.S. Patent No. 9,176,377B2, to Stowers et al., entitled “Patterned Inorganic Layers, Radiation Based Patterning Compositions and Corresponding Methods,” which is incorporated herein by reference. Related resist compounds are discussed in U.S. Patent Application Publication No. 2013 / 0224652A1, to Bass et al., entitled “Metal Peroxo Compounds With Organic Co-ligands for Electron Beam, Deep UV and Extreme UV Photoresist Applications,” which is incorporated herein by reference. Effective types of resists have been developed using alkyl ligands as described in U.S. Patent No. 9,310,684B2, entitled “Organometallic Solution Based High Resolution Patterning Compositions,” U.S. Patent Publication No. 2016 / 0116839A1, entitled “Organometallic Solution Based High Resolution Patterning Compositions and Corresponding Methods,” and U.S. Patent Publication No. 15 / 291738, entitled “Organotin Oxide Hydroxide Patterning Compositions, Precursors, and Patterning,” all of which are incorporated herein by reference.Tin compositions are exemplified in these patent documents, and the data presented herein focus on tin-based resists, but the edge bead removal solution described herein is expected to be effective for other metal-based resists as follows.

[0012] With particular reference to tin-based resists, these resists are based on the chemistry of organometallic compositions represented by the formula R z SnO (2-(z / 2)-(x / 2)) (OH) x where 0 < z ≦ 2 and 0 < (z + x) ≦ 4, and R is a hydrocarbyl group having 1 to 31 carbon atoms. However, at least some of the oxo / hydroxo ligands can be formed post-deposition based on in-situ hydrolysis based on compositions represented by the formula R n SnX 4-n where n = 1 or 2 and X is a ligand having a hydrolyzable M-X bond. Generally, suitable hydrolyzable ligands (X in RSnX3) include alkynides RC≡C, alkoxides RO - , azides N3 - , carboxylates RCOO - , halides and dialkylamides. Thus, in some embodiments, all or part of the oxo-hydroxy composition can be replaced with Sn-X compositions or mixtures thereof. The R-Sn boundary is generally radiation-sensitive and forms the basis for the radiation-processable aspect of the resist. However, some of the R z SnO (2-(z / 2)-(x / 2)) (OH) x compositions can be replaced with MO ((m / 2)-l / 2) (OH) l where 0 < z ≦ 2, 0 < (z + w) ≦ 4, m = the formal valence of M m+ , 0 ≦ l ≦ m, y / z = (0.05 to 0.6) and M = M’ or Sn, where M’ is a non-tin metal of Groups 2 to 16 of the periodic table and R is a hydrocarbyl group having 1 to 31 carbon atoms. Thus, the resist processed during edge bead rinse is R z SnO (2-(z / 2)-(x / 2)) (OH)x , R’ n SnX 4-n and / or MO ((m / 2)-l / 2) (OH) l may include a selected mixture of. In this case, generally, a significant portion of the composition contains alkyl-tin bonds. Other resist compositions include, for example, compositions having a metal carboxylate bond such as dibutyltin diacetate (ligands such as acetate, propanoate, butanoate, benzoate, etc.).

[0013] While the metal oxo / hydroxo or carboxylate-based resists mentioned above are particularly preferred, in some embodiments, several other high-performance resists may be suitable. Specifically, other metal-based resists include those with high etching selectivity for templates, fillers, and buffer hard masks. These may include resists such as metal oxide nanoparticle resists (e.g., Jiang, Jing; Chakrabarty, Souvik; Yu, Mufei et al., “Metal Oxide Nanoparticle Photoresists for EUV Patterning”, Journal Of Photopolymer Science And Technology 27(5), 663-666 2014, incorporated herein by reference) or other metal-containing resists (e.g., A Platinum-Fullerene Complex for Patterning Metal Containing Nanostructures, DXYang, A. Frommhold, DSHe, ZYLi, REPalmer, MALebedeva, TWChamberlain, ANKhlobystov, APGRobinson, Proc SPIE Advanced Lithography, 2014, incorporated herein by reference). Other metal-based resists are described in U.S. Patent Application Publication No. 2009 / 0155546A1 to Yamashita et al., entitled “Film-Forming Composition, Method for Pattern Formation, and Three-Dimensional Mold,” and U.S. Patent No. 6,566,276 to Maloney et al., entitled “Method of Making Electronic Materials,” both of which are incorporated herein by reference.

[0014] In the processing of electronic equipment, it is generally desirable to reduce trace metal contamination, and therefore, it is desirable to use organometallic resists to remove tin and / or other metal residues potentially arising from the resist. Improved edge bead removal solutions generally comprise an organic solvent and one or more additives, where the additives can improve metal removal. Suitable additives include, for example, organic acids, inorganic fluoroacids, tetraalkylammonium halides, and mixtures thereof. Suitable additives may also function as complexing or chelating agents, such as carboxylates, dicarboxylates, halides, phosphates, phosphonates, sulfates, sulfonates, and mixtures thereof. Additives may also function as surfactants and / or chelating agents. Therefore, conjugated anions of various acids listed herein can be added as chelating agents. Similarly, nonionic surfactants such as Triton TMSurfactants such as -X can also be used as additives. Additives can be selected so as to be soluble in organic solvents. The solution may contain about 0.1% to about 25% by weight of the additive, in a further embodiment about 0.2% to about 20% by weight, and in an additional embodiment about 0.25% to about 20% by weight of the additive. Those skilled in the art will recognize that other ranges of additive concentrations within the express range above are intended and that they are within the scope of this disclosure. Suitable organic solvents include, for example, glycol ethers and their esters such as propylene glycol methyl ether (PGME), propylene glycol methyl ethyl acetate (PGMEA), propylene glycol butyl ether (PGBE), and ethylene glycol methyl ether; alcohols such as ethanol, propanol, isopropyl alcohol, isobutyl alcohol, hexanol, ethylene glycol, and propylene glycol; cyclic esters such as gamma-butyrolactone; esters and / or mixtures thereof such as n-butyl acetate and ethyl acetate; ketones such as heptanone; liquid cyclic carbonates such as propylene carbonate and butylene carbonate, and any mixtures thereof. A mixed solvent containing approximately 50 to 90% by weight of PGMEA, approximately 1% to 20% by weight of PGME, approximately 1% to 10% by weight of γ-brilolactone, and approximately 1% to 20% by weight of n-butyl acetate is proposed as a desirable EBR solution having desirable rheological and evaporation properties in U.S. Patent No. 8,227,182, entitled "Methods of Forming a Photosensitive Film," to Lee et al., incorporated herein by reference. Suitable organic acids include, for example, carboxylic acids such as acetic acid, citric acid, oxalic acid, 2-nitrophenylacetic acid, 2-ethylhexanoic acid, and dodecanoic acid; sugar acids such as ascorbic acid, tartaric acid, and glucuronic acid; sulfonic acids such as benzenesulfonic acid and p-toluenesulfonic acid; phosphoric acids such as phosphate esters and bis(2-ethylhexyl) phosphate; hydrofluoric acid (HF); sulfuric acid (H2SO4); and any mixtures thereof. Suitable inorganic fluoroacids include, for example, hexafluorosilicic acid, hexafluorophosphate, and fluoroboric acid.Suitable tetraalkylammonium compounds include, for example, tetramethylammonium fluoride, tetrabutylammonium fluoride, tetrabutylammonium fluorosilicate, etc. or mixtures thereof.

[0015] Multiple rinse steps can be performed to achieve the desired level of edge cleaning. In some embodiments, to achieve the desired reduction of metal, the edge rinse can be performed 1, 2, 3, 4, 5, 6, 10, or 11 or more times with the same solution. Further, two different rinse solutions can be applied during the edge bead rinse process. The different solutions can be selected independently from the above solutions. Generally for wafers with a diameter of about 3 inches to about 18 inches, during each application, the solution can be delivered in an amount of about 0.05 milliliters (mL) to about 50 mL, in further embodiments about 0.075 mL to about 40 mL, and in other embodiments about 0.1 mL to about 25 mL. In some embodiments, the solution can be sprayed at a flow rate of about 5 mL / min to about 50 mL / min, and the solution can be applied over a period of about 1 second to about 5 minutes, in further embodiments about 5 seconds to about 2 minutes. Those skilled in the art will recognize that other ranges of solution application times and amounts are contemplated within the above explicit ranges and that they are within the scope of the present disclosure.

[0016] A device for performing edge bead removal is shown in Figure 1. Referring to Figure 1, the wafer processing apparatus 100 includes a spindle 102 having a hollow core 104, connected to a motor for rotating the spindle and a pump configured to apply negative pressure to the hollow core of the spindle; a chuck 106 operably connected to the spindle and rotating with the spindle; and a fluid dispenser 108 supported on the chuck 106 and configured to distribute fluid 110 to one or both edges of a wafer held in place by the negative pressure in the hollow core 104. A wafer 112 appropriately positioned within the apparatus is shown in Figure 1. The fluid dispenser 108 may include a nozzle for directing the fluid towards the wafer. A reservoir 114 is operably connected to the fluid dispenser 108 that supplies the fluid. The reservoir may be a container suitable for holding fluid connected to pipes, hoses, etc., and the movement of fluid from the reservoir 114 can be driven using gravity or a pump. The negative pressure applied to the hollow core 104 can be supplied by a negative pressure device 116. The negative pressure device may be a pump, aspirator, blower, etc. The spindle 102 can also be connected to a motor 118. The motor may have an appropriate design and mounting for spinning the spindle 102 for wafer processing. A specific apparatus design for edge bead processing is described in U.S. Patent No. 8,826,926B2 to Chalom et al., entitled “Methods of Profiling Edges and Removing Edge Beads,” which is incorporated herein by reference.

[0017] The edge bead rinsing process is schematically shown in Figure 2. As shown in the image on the left, a substrate 120 is obtained and coated 122 with a metal-based resist 124. Next, a bead edge rinsing step 126 is performed to remove the resist along the edges 128 of the substrate 120 to form an edged resist layer 130. The edge bead rinsing process is further described above in terms of composition, amount of composition and delivery apparatus. The resulting structure 132 having the edged resist layer 130 can then be used in the patterning step of the substrate 120. Wafer coating with resist can be performed, for example, by depositing about 0.25 mL to about 20 mL of resist solution in a suitable configuration onto a stationary wafer, and then spreading the resist by spin-rotating the wafer for a time of about 5 seconds to about 15 minutes at, for example, 250 rpm to 10,000 rpm. The spin rotation speed can be varied over the spin rotation time as needed. Those skilled in the art will recognize that other ranges of fluid volume, spin rotation speed and spin rotation time are intended within the express range above and that they are within the scope of this disclosure.

[0018] To perform the rinsing step, the wafer can generally be spun at a low to medium speed during fluid deposition, and then at a higher speed after fluid deposition. The edge bead rinsing solution can be applied not only to the edges of the wafer but also to the back surface. For example, the wafer can be spun at 5 rpm to 10,000 rpm during fluid deposition, and in further embodiments, at 50 rpm to 5,000 rpm. The liquid deposition process can be carried out over a period of 1 second to 5 minutes, and in further embodiments, over a period of about 5 seconds to about 3 minutes. Following liquid deposition, the wafer can be spun at a speed of at least 500 rpm, and in further embodiments, at a speed of 750 rpm to 6,000 rpm, and the spin rotation after liquid deposition can be carried out over a period of 2 seconds to 10 minutes, and in further embodiments, over a period of 5 seconds to about 5 minutes. The spin rotation speed can be varied over the spin rotation time as needed. Those skilled in the art will recognize that other ranges of spin rotation speeds and spin rotation times are intended within the express ranges described above and that they are within the scope of this disclosure. Following the spin rotation after deposition, a subsequent rinsing step can be performed, and this process can be repeated as selected.

[0019] After applying the edge bead solution to remove the edge bead, the wafer edge may appear clearly clean to inspection, as shown in Figure 3, with a clean edge 134. As described above, the edge bead rinsing process may involve multiple rinsing steps using the same and / or different rinsing solutions to achieve the desired result. To fully evaluate the removal of metal, the wafer can be inspected for residual metal. A suitable technique in practical use for evaluating trace metals generally involves inductively coupled plasma mass spectrometry (ICP-MS). A variation of this analytical technique, called vapor-phase decomposition-inductively coupled plasma mass spectrometry (VPD-ICP-MS), can be used to evaluate the silicon wafer surface. Using this technique, the amount of residual metal per unit area of ​​the wafer surface along the edge can be determined. In the case of the tin-based resist described in the examples, the amount of residual tin obtained is approximately 100 × 10⁶ of the wafer area relative to the wafer area of ​​the rinsing region. 10 atoms / cm 2 In further embodiments, approximately 25 × 10 10 atoms / cm 2 In the following, and in additional embodiments, approximately 10 × 10 10 atoms / cm 2 Preferably, the following applies: A person skilled in the art will recognize that other ranges of residual tin are intended within the express scope described above and that they fall within the scope of this disclosure.

[0020] In addition to using the improved EBR solutions described above, coatings can be applied along the substrate edge or across the entire substrate to further facilitate the reduction of residual metal along the wafer edge after EBR processing. Such coatings are generally insoluble in the photoresist coating solution and may or may not be completely or substantially removed as part of the subsequent EBR process. After coating, a resist solution can be deposited, which may or may not cover the coating, as will be further described below. In some embodiments, a suitable coating may be a sacrificial material such as polystyrene or amorphous carbon, which may or may not cover the entire substrate. It may also be selectively removed with respect to the resist coating during the subsequent EBR process. If the coating covers the entire wafer, the remaining coating can be used as a layer that can be etched differently within the patterning stack, as in the case of amorphous carbon. In other embodiments, a suitable polymer coating, such as polystyrene, can be applied only along the periphery of the wafer and may be at least partially removed during the subsequent EBR process. In this case, the coating can be removed by EBR processing of the resist material, or alternatively by alternating EBR processing. In other embodiments, a suitable coating, such as a surface modification layer coating or an anti-adhesion coating, may cover only the periphery of the wafer to prevent the resist solution from adhering to the coating surface during resist deposition, and may or may not be removed during the subsequent EBR process.

[0021] Therefore, the improved treatment may relate to coating the edge surface region or the entire surface of the wafer with a secondary sacrificial material before coating with a metal-based resist. In additional or alternative embodiments, the improved treatment may include coating the wafer edge surface region with a surface treatment layer that prevents the edge surface region from wetting with the resist precursor solution. Generally, both sacrificial and anti-adhesion layers do not require a baking step before resist coating and EBR, providing a desirable process flow. While we do not wish to be limited to theory, it is believed that anti-adhesion materials and processes suppress the adhesion of metal-containing species to the substrate surface, thereby making it easier to more completely remove the photoresist with reduced metal residue when a suitable EBR solvent or mixture is applied. The improved rinsing solutions described herein have proven particularly effective in removing residual tin atoms and can be used as standalone EBR solutions or in combination with the sacrificial or surface treatment layers described herein. As illustrated by the materials and methods of the examples, the level of residual tin after EBR treatment can be reduced to an acceptable level using the methods described herein.

[0022] The choice of composition for the sacrificial material may be influenced by whether the coating covers the entire substrate / wafer, or only the edges. Generally, the sacrificial material may or may not be completely removed during bead edge rinsing, as long as the presence of the sacrificial material is advantageous for the removal of metal ions along the bead edge from the bead edge. If the sacrificial layer covers the wafer, the sacrificial layer may also be removable when the corresponding resist is removed, with or without irradiation. Specifically, the sacrificial material may be selected to be removed using a developer for the resist. In addition or alternatively, sacrificial layers, such as amorphous carbon layers or spin-on carbon layers, can be removed during the etching step on the wafer / substrate material. Spin-on carbon materials are commercially available from JSR Corporation (Japan). Furthermore, see, for example, U.S. Patent No. 9,102,129B2 to Krishnamurthy et al., “Spin-on Carbon Compositions for Lithographic Processing,” which is incorporated herein by reference. Spin-on carbon materials can be coated using appropriate coating processes and can also be dried, for example, by heating. The deposition of a CVD carbon layer is described, for example, in U.S. Patent Application Publication No. 2007 / 0037014 to Nagata, entitled “Method of Forming a Protective Film and a Magnetic Recording Medium Having a Protective Film Formed by the Method,” which is incorporated herein by reference. A sacrificial coating is described that modifies the surface edges of the substrate without heating or other post-treatment, allowing for the removal of the tin-based resist along with the edge portions of the protective coating during EBR processing. A specific example using polystyrene as an edge coating for use with a tin-based resist is described below.

[0023] Figure 4 schematically illustrates the process of covering the entire substrate with a sacrificial material. After the substrate 150 is obtained, a layer of sacrificial material is coated 152 onto the substrate 150 to form a sacrificial layer 154. The coating of the sacrificial layer 154 can be carried out, for example, using a coating solution suitable for deposition of amorphous carbon using spin coating, spray coating, knife-edge coating, chemical vapor deposition (CVD), or other suitable coating techniques or a combination thereof, as described above. Next, a resist precursor solution can be deposited 156 to form a resist layer 158. The resist precursor solution is generally coated by spin coating, but spray coating or other coating treatments can be used. After forming the resist layer 158, an edge bead rinsing step 160 can be performed to form an edged structure 162 having an edged sacrificial layer 164 and an edged resist layer 166. The edge bead rinsing process has been further described above and can also be used for the process in Figure 4. A top view of the edged structure 162 is shown in inset A of Figure 4.

[0024] The process of covering the substrate with a sacrificial material can follow the procedure used for depositing the resist. A precursor solution for the sacrificial material can be deposited on a stationary wafer in an appropriate coverage area. The wafer can then be spun to distribute the fluid onto the wafer surface. The amount of fluid can be selected based on fluid properties such as concentration and viscosity, the desired thickness of the sacrificial material after drying, and other relevant parameters adjusted based on empirical evaluation. Generally, the amount of fluid can be about 0.1 mL to about 100 mL, and in further embodiments, about 0.25 mL to about 25 mL. After the fluid has been deposited, the wafer can be spun to distribute the fluid onto the wafer in order to spread it. In this case, the wafer can be spun at 250 rpm to 10,000 rpm, and in further embodiments, 450 rpm to 6,000 rpm for a time of 2 seconds to 10 minutes, and in further embodiments, for a time of 5 seconds to 5 minutes. The spin speed can be varied over the spin time as needed. Multiple deposition and spin steps can be used as needed to achieve the desired coating. Those skilled in the art will recognize that other ranges of fluid volume, spin rotation speed, and spin rotation time are intended within the express range described above and that they fall within the scope of this disclosure.

[0025] The use of a sacrificial layer along the edge is schematically illustrated in Figure 5. After obtaining the substrate 180, a sacrificial layer coating material can be applied 182 along the edge of the substrate 180 to form an edge-protected structure 184 having a sacrificial ring 186 on the substrate 180. The application of the sacrificial layer coating material can be carried out along the edge, for example, using a beading apparatus modified to deliver the coating material along the edge. During the delivery of the coating material, the substrate can be spun and rotated at a speed consistent with maintaining at least a substantial portion of the coating material along the edge. A top view of the edge-protected structure 184 is shown in inset A of Figure 5. Next, a resist solution can be deposited 188 on the edge-protected structure 184 to form a resist layer 190. Then, the edge beading process 192 removes both the sacrificial ring 186 and the resist material along the edge to form an edge-bearing structure 194 having an edge-bearing resist layer 196 on the substrate 180. The edge beading process has been further described above and can be similarly used with respect to the process in Figure 5. A top view of the edged structure 194 is shown in inset B of Figure 5.

[0026] An alternative method for providing clean bead edges involves applying an edge coating surface treatment to suppress resist deposition along the edge. In particular, an edge coating composition can be applied whose critical surface tension is less than the surface tension of the resist coating composition. Critical surface tension (CST) is a property of solid surfaces. Most inorganic solids, such as the surface of a silicon wafer, are hard and correspondingly have high critical surface tension. Therefore, most liquids wet silicon wafers. A coating with low surface tension, such as a silane or fluorinated compound, can be applied as a surface treatment agent that functions as an anti-adhesion coating along the wafer edge. The anti-adhesion coating can be applied to the wafer edge before the resist is applied. Once the resist is applied, the resist will not adhere substantially along the edge. Next, a bead edge rinse is performed following the resist application to remove any small amount of resist that may remain along the edge. After the bead edge rinse, processing can continue as usual. Since the edge is not patterned, the anti-adhesion coating along the edge does not need to be removed or processable during the wafer patterning process.

[0027] Suitable anti-adhesion compositions include, for example, fluorinated vinyl polymers such as polytetrafluoroethylene and copolymers thereof. Fluoropolymers can be fully fluorinated or not fully fluorinated, i.e., they can be perfluoropolymers. Alkylhalogenated silanes can also be useful in providing anti-adhesion surfaces with low critical surface tension. Suitable silanes include alkyltrichlorosilanes such as heneicosafluorododecyltrichlorosilane (CST ≈ 6-7 dynes / cm at 25°C), heptadecylfluorodecyltrichlorosilane (CST ≈ 12 dynes / cm at 25°C), and octadecyltrichlorosilane (CST ≈ 20-24 dynes / cm at 25°C). Alkyltrialkoxysilanes can also provide sufficient anti-adhesion properties for resists with somewhat higher surface tension. Suitable alkyltrialkoxysilanes include, for example, methyltrimethoxysilane (CST ≈ 22.5 dynes / cm at 25°C), nonafluorohexyltrimethoxysilane (CST ≈ 23 dynes / cm at 25°C), or mixtures thereof. The illustrated alkyloxyhydroxytin-based resists exemplified herein had a surface tension of about 23 dynes / cm at 25°C. The choice of anti-adhesion coating material may generally be influenced by the composition of the resist, but the coating compositions generally have a critical surface tension of about 50 dynes / cm or less at 25°C, and in further embodiments, about 30 dynes / cm or less, and in further embodiments, about 22 dynes / cm or less. Those skilled in the art will recognize that other ranges of critical surface tensions are intended within the express ranges above and that they are within the scope of this disclosure.

[0028] Fluoropolymers can be partitioned, for example, as a dispersion of polymer fine particles. The liquid of the dispersion may be a fluorinated alkane such as perfluorohexane, perfluorooctane, or a mixture thereof. Silanes can be partitioned in a suitable solvent such as methylene chloride, tetrahydrofuran (THF), toluene, or other suitable organic solvents or mixtures thereof.

[0029] Figure 6 schematically illustrates the application of an anti-adhesion coating along the substrate edge. After obtaining the substrate 210, a solution of the surface modification material is applied 212 to form an edge-protected structure 214 having an anti-adhesion edge coating 216 along the substrate 210. The application of the surface modification material to form the anti-adhesion edge coating 216 can be carried out, for example, using an edge beading apparatus modified to deliver the material under appropriate conditions and leave a substantial amount of coating material on the substrate edge. A top view of the edge-protected structure 214 is shown in inset A of Figure 6. Next, a resist precursor solution is deposited 218 onto the edge-protected structure 214 to form an edged resist layer 220. The resist precursor solution can be applied using spin coating, spray coating or other suitable techniques. A top view of the structure having the edged resist layer 220 is shown in inset B of Figure 6. Next, edge bead rinsing 222 is performed to remove all residual resist along the edge, and optionally all or part of the anti-adhesion edge coating 216, to form a rinsed structure 224 having a rinsed edge 226. The rinsed edge may or may not include the residual anti-adhesion edge coating. Edge bead rinsing is performed as described above. A top view of the rinsed structure 224 is shown in inset C of Figure 6.

[0030] With regard to the application of a sacrificial coating along the wafer edge, as schematically shown in Figure 5, or the application of a surface modification composition, as schematically shown in Figure 6, the wafer can generally be spun at a low to medium speed during fluid deposition, and then at a higher speed after fluid deposition. For example, the wafer can be spun at 5 rpm to 500 rpm during fluid deposition, and in further embodiments, at 10 rpm to 250 rpm. The liquid deposition process can be carried out over a period of 5 seconds to 5 minutes, and in further embodiments, over a period of about 15 seconds to about 3 minutes. Following liquid deposition, the wafer can be spun at a speed of at least 500 rpm, and in further embodiments, at a speed of 750 rpm to 4000 rpm, and the spin rotation after liquid deposition can be carried out over a period of 5 seconds to 10 minutes, and in further embodiments, over a period of 10 seconds to about 5 minutes. The spin rotation speed can be varied over the spin rotation time as needed. Those skilled in the art will recognize that other ranges of spin rotation speeds and spin rotation times are intended within the express range described above and that they are within the scope of this disclosure. Following the spin rotation after deposition, a subsequent rinsing step can be performed, and this process can be repeated as selected.

[0031] In general, with respect to surface modification coatings (e.g., sacrificial coatings or anti-adhesion coatings) along edges or on wafer surfaces, the dried coating may be about 10 microns or less in some embodiments, about 5 microns or less in some embodiments, and about 1 micron or less in further embodiments. In additional or alternative embodiments, thinner coatings, e.g., coatings of about 1 nm to about 500 nm, coatings of about 5 nm to about 250 nm in further embodiments, and coatings of about 7 nm to about 100 nm in other embodiments may be desirable. Those skilled in the art will recognize that other ranges are intended within the expressly defined thickness ranges above and that they are within the scope of this disclosure. Both the concentration and the thickness of the liquid coating can be adjusted to achieve a coating of the desired thickness.

[0032] In all embodiments, those skilled in the art will recognize that the identity of the substrate is not limited except by reasonable constraints recognized by those skilled in the art, such as size suitable for the process apparatus and sufficient mechanical strength to withstand the processing. Suitable substrate surfaces may include ceramics such as silicon, including single-crystal silicon, polycrystalline silicon, amorphous silicon, silicon oxide, titanium oxide, or other suitable materials or combinations thereof. The substrate surface may or may not have been patterned prior to the commencement of a further patterning process in which the EBR treatment is part of a particular patterning step. [Examples]

[0033] Example 1 - Selected EBR solvent and carboxylic acid additive This embodiment demonstrates the effectiveness of organic solvents containing carboxylic acid additives for effective residue removal using tin-based radiation-patternable resists.

[0034] Experiments were conducted using two different radiation-patternable resists. R1 resist contained an organometallic tin oxyhydroxide resist containing a mixture of two different alkyl ligands, while R2 resist contained a mixture of an organometallic tin oxyhydroxide resist containing alkyl ligands and a tin oxyhydroxide composition without alkyl ligands. The resists were deposited onto single-crystal silicon wafers by spin coating. Immediately following resist deposition, the wafer was set to rotate at 50 rpm, while 5 mL of rinse solution was distributed onto the wafer to cover the entire surface. Immediately after distribution of the rinse solution, the wafer was spun at 1500 rpm for 45 seconds until dry. In some cases, as shown in Table 1, after the spin-drying of the first rinse solution, a second rinse solution was distributed onto the wafer and processed in the same manner, i.e., distributed onto the wafer while rotating at 50 rpm, and then spun at 1500 rpm for 45 seconds to dry. The next volume of rinse solution was dispensed immediately after this high-speed spin rotation as needed, and the procedure was typically repeated five times as described above until after the high-speed spin rotation following the application of the final rinse solution. The residue removal evaluated in these tests is considered to be close to the effectiveness of an edge bead rinse process that rinses only the wafer edges.

[0035] Residual metals were measured using ChemTrace® with bevel-edge vapor-phase decomposition-inductively coupled plasma-mass spectrometry (VPD-ICP-MS). The results in Tables 1 and 2 were obtained using resist R1, and the results in Table 3 were obtained using resist R2. To obtain the results in Table 1, a total of 5 rinsing steps were performed, with 5 ml per rinsing step and one dry spin between each rinsing step. In Tables 2 and 3, "n × mL," such as 4 × 3 mL, indicates multiple rinsing steps of a specific volume using the same solution. Therefore, 4 × 3 mL would indicate 4 rinsing steps, each using 3 mL of solution. Table 4 lists the solvents and additives used in the previous tables. As the results show, R2 presented a greater challenge regarding the desired removal of tin, although desirable results were obtained with appropriate rinsing solutions. However, for both resists, rinsing solutions containing additives were successful in reducing tin.

[0036] [Table 1]

[0037] [Table 2]

[0038] [Table 3]

[0039] [Table 4]

[0040] Example 2 - Selected EBR solvent and fluorinated acid additive This embodiment demonstrates the effectiveness of an organic solvent containing a fluorinated acid additive for effective bead edge rinsing using a tin-based radiation-patternable resist.

[0041] These experiments were performed using tin-based resists R1 and R2, as mentioned in Example 1. The tests were carried out as described in Example 1, with the fluorinating additives replaced. All tests in this example consisted of a single 5 mL EBR rinse step, followed by a 5 × 5 mL rinse with a PGME / PGMEA solvent mixture. The results obtained for R1 are shown in Table 5, and the results obtained for R2 are shown in Table 6. In the tables, N represents the equivalent amount per liter using standard notation. These additives were particularly effective for the R2 resist. The solvents and additives used in this example are shown in Table 7.

[0042] [Table 5]

[0043] [Table 6]

[0044] [Table 7]

[0045] Example 3 - Sacrificial Edge Substrate This embodiment demonstrates an improvement to EBR processing based on applying a sacrificial layer across the wafer surface.

[0046] A coating solution was applied to form a sacrificial underlayer coating across the entire wafer. The coating solution contained 5% by weight of polystyrene dissolved in PGMEA, and this was applied to two wafers, with two more wafers used as controls. In each case, 5 mL of the coating solution was distributed onto a 100 mm wafer rotating at 50 rpm. Immediately after the distribution process, the wafers were spun at 1500 rpm for 45 seconds. Next, 1.5 mL of an organic tin-based resist solution R2 was distributed onto three wafers (two wafers with coated edges and one control wafer) in a stationary position, and immediately after the distribution of the resist solution, each wafer was spun at 1500 rpm for 45 seconds.

[0047] At the end of the wafer spin rotation to spread the resist solution, edge bead rinsing (EBR) was performed using 5 mL of EBR rinse solution for 5 cycles, as described in Example 1, excluding a control wafer without resist that was not EBR rinsed. For the control wafer containing resist but without edge coating, the EBR rinse solution was 65 / 35 vol% PGME / PGMEA, while for wafers with sacrificial edge coating, the EBR solvent was either PGMEA or 2-heptanone. Measurements were performed to evaluate the tin concentration along the edges of the four wafers, and the results are shown in Table 8. Edge coating significantly improved the EBR process.

[0048] [Table 8]

[0049] Example 4 - Anti-adhesion coating in the circumferential direction This embodiment demonstrates an improvement to EBR processing based on applying an anti-adhesion edge coating to a wafer.

[0050] A coating solution was applied to form an anti-adhesion edge coating. The coating solution contained 1 wt% poly(4,5-difluoro-2,2-bis(trifluoro-methyl)-1,3-dioxol-co-tetrafluoroethylene (FEO)) dissolved in perfluorooctane (Solution 1) or tetradecafluorohexane (Solution 2). Solution 1 and Solution 2 were applied to separate wafers, and two additional wafers were used as controls. To apply the coating solution, 5 mL of the coating solution was distributed into the EBR apparatus along the edge of a 100 mm wafer rotating at 500 rpm. Immediately after the distribution process, the wafer was spun at 1500 rpm for 45 seconds. Next, 1.5 mL of an organic tin-based resist solution R2 was distributed onto three wafers (two coated wafers and one control wafer) in a stationary position, and immediately after the distribution of the resist solution, each wafer was spun at 1500 rpm for 45 seconds.

[0051] At the end of the wafer spin rotation to spread the resist solution, edge bead rinsing (EBR) was performed using 5 cycles of rinsing with 5 mL of EBR rinsing solution, as described in Example 1, except for a control wafer without resist that was not EBR rinsed. The EBR rinsing solution was 65 / 35 vol% PGME / PGMEA for the control wafer containing resist but without coating, PGMEA for the first wafer containing a sacrificial coating, and the solvent used for EBR was the same as the solvent used to deposit the coating solution for the wafer containing an anti-adhesion edge coating. Measurements were performed to evaluate the tin concentration along the edges of the four wafers, and the results are shown in Table 9. Edge coating significantly improved the EBR process.

[0052] [Table 9]

[0053] The embodiments described above are intended to be illustrative and not limiting. Additional embodiments are available in the claims. In addition, while the invention has been described in relation to specific embodiments, those skilled in the art will recognize that modifications in form and detail are possible without departing from the spirit and scope of the invention. Any incorporation by reference to the above-mentioned documents is limited so as not to incorporate any subject matter contrary to the express disclosure herein. To the extent that a particular structure, composition and / or process is described herein using components, elements, components or other subdivisions, the disclosure herein is understood to encompass not only embodiments including specific embodiments, specific components, elements, components, other subdivisions or combinations thereof, but also embodiments substantially composed of such specific components, components or other subdivisions or combinations thereof, which may include additional features that do not alter the fundamental nature of the subject matter, as suggested in the description.

Claims

1. A method for removing edge beads on a wafer associated with a resist coating comprising a metal-based resist composition, comprising the steps of spin-coating the wafer with the metal-based resist composition, and then applying a first bead edge rinse solution along the wafer edge, wherein the edge bead solution comprises an organic solvent and an additive comprising a carboxylic acid, an inorganic fluorinated acid, a tetraalkylammonium compound, or a mixture thereof.

2. The method according to claim 1, wherein the metal-based resist composition comprises an alkyloxo / hydroxotin moiety.

3. The first edge bead linse solution is applied along the wafer edge in an amount of about 0.5 mL to about 20 mL, and the method involves spinning the wafer at a speed of at least about 500 rpm after the delivery of the first edge bead linse solution, and using a VPD-ICP-MS, measuring along the treated edge in an amount of about 50 × 10⁻¹⁶. １０ atoms / cm ２ The method according to claim 1 or 2, further comprising the step of obtaining the following residual tin measurement values.

4. The method according to claim 3, wherein the coating step and the spinning step are repeated 1 to 20 times using the first edge bead linse solution.

5. The method according to claim 3, wherein the steps of coating and spinning are repeated at least once and 1 to 20 times using a second edge beadlinse solution different from the first edge beadlinse solution.

6. The method according to any one of claims 1 to 5, wherein the solvent comprises a glycol ether or an ester thereof, an alcohol, a ketone, a liquid cyclic carbonate, or a mixture thereof.

7. The aforementioned additives include acetic acid, citric acid, oxalic acid, 2-nitrophenylacetic acid, 2-ethylhexanoic acid, dodecanoic acid, ascorbic acid, tartaric acid, glucuronic acid, benzenesulfonic acid, p-toluenesulfonic acid, and sulfuric acid (H ２ SO ４ The method according to any one of claims 1 to 6, comprising ) or a mixture thereof.

8. The method according to any one of claims 1 to 6, wherein the additive comprises hexafluorosilicic acid.

9. The method according to any one of claims 1 to 6, wherein the additive comprises tetramethylammonium fluoride, tetrabutylammonium fluoride, tetrabutylammonium fluorosilicic acid, or a mixture thereof.

10. A method for preparing wafers for radiation-based patterning, The steps include applying a protective composition to the wafer, The steps include applying the protective composition, followed by spin-coating with a metal-based resist composition, The steps include spin-coating the metal-based resist composition, followed by performing edge beading by applying an edge beading solution along the edge of the wafer, and A method that includes this.

11. The method according to claim 10, wherein the protective composition is applied along the edge of the wafer.

12. The method according to claim 11, wherein the protective composition comprises a non-volatile component having a dry critical surface tension of about 30 dynes / cm or less at 25°C.

13. The method according to claim 12, wherein the non-volatile component comprises a vinyl fluoride polymer or an alkylhalogenated silane.

14. The method according to claim 10 or 11, wherein the protective composition comprises a sacrificial polymer material that facilitates the removal of metal along the edge.

15. The method according to claim 14, wherein the sacrificial polymer is polystyrene.

16. The method according to any one of claims 10 to 15, wherein the protective composition is applied along the wafer edge in an amount of about 0.5 mL to about 20 mL, and the method further comprises the step of spinning the wafer at a speed of at least about 500 rpm after the delivery of the protective composition.

17. The method according to any one of claims 10 to 16, wherein the solvent comprises a glycol ether or an ester thereof, an alcohol, a ketone, a liquid cyclic carbonate, or a mixture thereof.

18. The additives include carboxylic acids, sugar acids, sulfonic acids, phosphoric acid, and sulfuric acid (H ２ SO ４ The method according to claim 17, comprising an inorganic fluoro acid, a tetraalkylammonium compound, or a mixture thereof.

19. It is a device, A spindle including a wafer support, which is operably connected to a motor configured to rotate the spindle, A dispenser having a nozzle configured to deposit fluid along the edge of a wafer mounted on the spindle, A fluid reservoir configured to deliver the fluid to the nozzle for distribution, An apparatus comprising, wherein the fluid contains an organic solvent to which an additive is added, the additive being a surface modifier, an acidic compound, a tetraalkylammonium compound, or a mixture thereof.

20. The apparatus according to claim 19, wherein the spindle has a hollow core, and the wafer support includes a negative pressure device configured to apply negative pressure within the hollow core and, based on the negative pressure, hold a wafer supported on the spindle.

21. The apparatus according to claim 19 or 20, wherein the organic solvent comprises a glycol ether or its ester, an alcohol, a ketone, a liquid cyclic carbonate, or a mixture thereof.

22. The apparatus according to claim 19 or 20, wherein the organic solvent comprises propylene glycol methyl ether (PGME), propylene glycol methyl ethyl acetate (PGMEA), propylene glycol butyl ether (PGBE), ethylene glycol methyl ether, ethanol, propanol, isobutyl alcohol, hexanol, ethylene glycol, propylene glycol, heptanone, propylene carbonate, butylene carbonate, or a mixture thereof.

23. The apparatus according to any one of claims 19 to 22, wherein the fluid contains the additive having a concentration of about 0.1% by weight to about 25% by weight.

24. The aforementioned additives include carboxylic acids, sugar acids, sulfonic acids, phosphoric acid, and sulfuric acid (H ２ SO ４ The apparatus according to any one of claims 19 to 23, comprising ) or a mixture thereof.

25. The apparatus according to any one of claims 19 to 23, wherein the additive comprises an inorganic fluoro acid, a tetraalkylammonium compound, or a mixture thereof.

26. The apparatus according to any one of claims 19 to 23, wherein the additive comprises a sacrificial polymer or compound having a dry critical surface tension of about 30 dynes / cm or less at 25°C.

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