US 10,394,127 B2  4  3  In a case where Re is the substituent and L$_{1 }$ is the linking  group, Re and L$_{1 }$may be bonded to each other to form a ring.  X represents a group capable of leaving by the action of  an acid.  <4> The pattern forming method as described in <3>, in  which the group represented by X in General Formula (1-1)  has a total number of carbon atoms and oxygen atoms of 4  or less.  <5> The pattern forming method as described in any one  of <l> to <4>, in which the content of the repeating unit  capable of decomposing by the action of an acid to generate  an acid having a pKa of3.0 or less is 55% to 100% by mole  with respect to all the repeating units of the resin.  <6> The pattern forming method as described in any one  of <l > to <5>, in which the resin further has a repeating unit  represented by General Formula (2).  In citations for a group ( atomic group) in the present  specification, in a case where the group is denoted without  specifying whether it is substituted or unsubstituted, the  group includes both a group not having a substituent and a  group having a substituent. For example, an "alkyl group"  includes not only an alkyl group not having a substituent  (unsubstituted alkyl group), but also an alkyl group having  a substituent (substituted alkyl group).  "Actinic rays" or "radiation" in the present specification  means, for example, a bright line spectrum of a mercury  lamp, far ultraviolet rays represented by an excimer laser,  extreme ultraviolet rays, X-rays, electron beams (EB), or the  like. In addition, in the present invention, light means actinic  rays or radiation.  Unless otherwise specified, "exposure" in the present  specification includes not only exposure by a bright line  spectrum of a mercury lamp, far ultraviolet rays represented  by an excimer laser, extreme ultraviolet rays, X-rays,  extreme ultraviolet rays, or the like, but also writing by  particle rays such as electron beams and ion beams.  In the present specification, a "(meth)acrylic monomer"  means at least one of monomers having a structure of  "CH$_{2}$=CH-CO-" or "CH$_{2}$=C(CH$_{3}$)----CO-". Simi› larly, "(meth)acrylate" and "(meth)acrylic acid" means "at  least one of acrylate or methacrylate" and "at least one of  acrylic acid or methacrylic acid".  In the present specification, the weight-average molecular  weight of the resin is a value measured in terms of poly› styrene by a GPC method. GPC follows a method using  HLC-8120 (manufactured by Tosoh Corporation), TSK gel  Multipore HXL-M (manufactured by Tosoh Corporation,  7.8 mmIDx30.0 cm) as a column, and tetrahydrofuran  (THF) or N-methyl-2-pyrrolidone (NMP) as an eluent.  Hereafter, the pattern forming method of the present  invention will be described in detail.  <Pattern Forming Method>  The pattern forming method of the present invention  includes:  a step (1) of forming a film using an actinic ray-sensitive  or radiation-sensitive resin composition (hereinafter also  referred to as a "composition") including a resin (hereinafter  also referred to as a "resin (A)") having an acid-decompos› able repeating unit capable of decomposing by the action of  an acid to generate an acid having a pKa of 3.0 or less,  a step (2) of exposing the film using actinic rays or  radiation, and  a step (3) of carrying out development using a developer  including an organic solvent after the exposure to form a  negative tone pattern.  According to the present invention, it is possible to  provide a pattern forming method having excellent perfor› mance of resolution and line width roughness as well as  reduction in film shrinkage (PEB shrinkage) in a PEB  process, particularly in the formation of an ultrafine pattern  (for example, a pattern having a line width of 20 nm hp or  less).  The reason thereof is not clear, but presumed as follows,  for example.  For example, it is thought that in a case where a film is  formed using a composition including a resin having an  acid-decomposable repeating unit capable of decomposing  by the action of an acid to generate methacrylic acid, and is  developed using a developer including an organic solvent  after the exposure to form a negative tone pattern, the  developer including an organic solvent permeates into the  pattern part, and thus, performance of resolution perfor› mance and line width roughness is deteriorated. In contrast,  Hereafter, embodiments of the present invention will be  described in detail.  According to the present invention, it is possible to  provide a pattern forming method having excellent perfor› mance of resolution and line width roughness as well as  reduction in film shrinkage (PEB shrinkage) in a PEB  process, particularly in the formation of an ultrafine pattern  (for example, a pattern having a line width of 20 nm hp or  less). In addition, according to the present invention, it is  possible to provide a method for manufacturing an elec› tronic device, including the pattern forming method.  DESCRIPTION OF THE PREFERRED  EMBODIMENTS  the pattern forming method as described in any one of  <l> to <10>.  <11> A method for manufacturing an electronic device,  comprising:  <10> The pattern forming method as described in any one  of <l> to <9>, in which the step (2) is a step of exposing the  film using electron beams, X-rays, or extreme ultraviolet  rays.  <9> The pattern forming method as described in any one  of <l> to <8>, in which the organic solvent includes an  ester-based solvent.  <8> The pattern forming method as described in any one  of <l> to <7>, in which the actinic ray-sensitive or radia› tion-sensitive resin composition contains a compound  capable of generating an acid with actinic rays or radiation.  <7> The pattern forming method as described in any one  of <l> to <6>, in which the resin does not contain a fluorine  atom.  In the formula,  R$_{11 }$ and R$_{12 }$ each independently represent a hydrogen  atom, an alkyl group, a cycloalkyl group, a halogen atom, a  cyano group, or an alkoxycarbonyl group. R$_{13 }$represents a  hydrogen atom, an alkyl group, a cycloalkyl group, a halo› gen atom, a cyano group, or an alkoxycarbonyl group, or is  bonded to Ar below to form a ring structure. Ar represents  an aromatic cyclic group. n represents an integer of 1 to 4.  (2) 