US 2020/0401045 Al  42  Dec. 24, 2020  [0520]  The pattern forming method of the embodiment of  the present invention is not particularly limited as long as it  includes the steps (i) to (iii), and may further include the  following steps.  [0535]  A light source wavelength used in the exposing  step is not particularly limited, and examples thereof include  infrared rays, visible light, ultraviolet rays, far ultraviolet  rays, extreme ultraviolet rays (EUV), X-rays, and electron  beams. Among those, far ultraviolet rays are preferable, and  a wavelength thereof is preferably 250 nm or less, more  preferably 220 nm or less, and still more preferably 1 to 200  mu. Specific examples thereof include a KrF excimer laser  (248 nm), an ArF excimer laser (193 nm), an F$_{2 }$ excimer  laser (157 mu), X-rays, EUV (13 mu), and electron beams,  the KrF excimer laser, the ArF excimer laser, EUV, or the  electron beams are preferable.  [0536]  In the developing step (iii), the developer may be  either an alkali developer or a developer including an  organic solvent (hereinafter also referred to as an organic  developer).  [0537]  As the alkali developer, a quaternary ammonium  salt typified by tetramethylammonium hydroxide is usually  used, but in addition to this, an alkaline aqueous solution  such as an inorganic alkali, primary to tertiary amines, an  alcoholamine, and a cyclic amine can also be used.  [0527]  In the pattern forming method of the embodiment  of the present invention, the film forming step (i), the  exposing step (ii), and the developing step (iii) described  above can be performed by a generally known method.  [0541]  The organic developer is preferably a developer  including at least one organic solvent selected from the  group consisting of a ketone-based solvent, an ester-based  solvent, an alcohol-based solvent, an amide-based solvent,  an ether-based solvent, and a hydrocarbon-based solvent.  [0542]  Examples of the ketone-based solvent include  1-octanone, 2-octanone, 1-nonanone, 2-nonanone, acetone,  2-heptanone  (methyl  amyl  ketone),  4-heptanone,  1-hexanone, 2-hexanone, diisobutyl ketone, cyclohexanone,  methylcyclohexanone, phenyl acetone, methyl ethyl ketone,  methyl isobutyl ketone, acetyl acetone, acetonyl acetone,  ionone, diacetonyl alcohol, acetyl carbinol, acetophenone,  methyl naphthyl ketone, isophorone, and propylene carbon› ate.  [0543]  Examples of the ester-based solvent include methyl  acetate, butyl acetate, ethyl acetate, isopropyl acetate, pentyl  acetate, isopentyl acetate, amyl acetate, propylene glycol  monomethyl ether acetate, ethylene glycol monoethyl ether  acetate, diethylene glycol monobutyl ether acetate, diethyl› ene glycol monoethyl ether acetate, ethyl-3-ethoxypropi› onate, 3-methoxybutyl acetate, 3-methyl-3-methoxybutyl  acetate, methyl formate, ethyl formate, butyl formate, propyl  formate, ethyl lactate, butyl lactate, propyl lactate, butyl  butyrate, methyl 2-hydroxyisobutyrate, isoamyl acetate,  isobutyl isobutyrate, and butyl propionate.  [0531]  The support is not particularly limited, and a sub› strate which is generally used in a step of manufacturing a  semiconductor such as an IC, and a process for manufac› turing a circuit board for a liquid crystal, a thermal head, or  the like, and other lithographic processes of photofabrication  can be used. Specific examples of the support include an  inorganic substrate such as silicon, SiO$_{2}$ ,  and SiN.  [0532]  For any of the prebaking step (iv) and the post› exposure baking step (v), the baking temperature is prefer› ably 70°  C. to 130°  C., and more preferably 80°  C. to 120°  C.  [0544]  As the alcohol-based solvent, the amide-based sol› vent, the ether-based solvent, and the hydrocarbon-based  [0533]  For any of the prebaking step (iv) and the  post-exposure baking step (v), the baking time is pref- [0530]  A protective film may be formed on the upper  layer of the resist film including the above-mentioned  hydrophobic resin.  [0540]  The alkali concentration, the pH, and the devel› opment time using the alkali developer can be appro› priately adjusted depending on a pattern formed.  [0539]  A time period for performing development the  using the alkali developer is usually 10 to 300 seconds.  [0538]  Furthermore, the alkali developer may include  an appropriate amount of alcohols and/or a surfactant.  The alkali concentration of the alkali developer is  usually 0.1 % to 20% by mass. The pH of the alkali  developer is usually 10 to 15.  [0529]  A protective film (topcoat) may be formed on the  upper layer of the resist film. As the protective film, a  known material can be appropriately used. For  example, the compositions for forming a protective  film  disclosed  in the  specification of US2007 /  0178407 A, the specification ofUS2008/0085466A, the  specification of US2007 /0275326A, the specification  of US2016/0299432A, the specification of US2013/  0244438A, or the specification of WO2016/157988A  can be suitably used. The composition for forming a  protective film preferably includes the above-described  acid diffusion control agent.  [0528]  In addition, a resist underlayer film (for example,  spin on glass (SOG), spin on carbon (SOC), and an  antireflection film) may be formed between the resist  film and the support, as desired. As a material consti› tuting the resist underlayer film, known organic or  inorganic materials can be appropriately used.  [0526]  The pattern forming method of the embodiment  of the present invention may include the post-exposure  baking step (v) a plurality of times.  [0525]  The pattern forming method of the embodiment  of the present invention may include the pre baking step  (iv) a plurality of times.  [0524]  The pattern forming method of the embodiment  of the present invention may include the exposing step  (ii) a plurality of times.  [0523]  The pattern forming method of the embodiment  of the present invention preferably includes a post› exposure baking (PEB) step (v) after the exposing step  (ii) and before the developing step (iii).  [0522]  The pattern forming method of the embodiment  of the present invention preferably includes a prebaking  (PB) step (iv) before the exposing step (ii).  [0521]  In the pattern forming method of the embodi› ment of the present invention, the exposing method in  the exposing step (ii) may be liquid immersion expo› sure.  [0534]  The baking may be performed using a unit  included in an exposure apparatus and a development  device, or may also be performed using a hot plate or  the like.  [0519]  (iii) a step of developing the exposed resist film  with a developer (developing step).  erably 30 to 300 seconds, more preferably 30 to 180  seconds, and still more preferably 30 to 90 seconds. 