US 2020/0192222 Al  1  Jun.  18,2020  RESIST COMPOSITION AND PATTERNING  PROCESS  CROSS-REFERENCE TO RELATED  APPLICATION  TECHNICAL FIELD  BACKGROUND ART  CITATION LIST  SUMMARY OF INVENTION  [0001]  This non-provisional application claims pnonty  under 35 U.S.C. § 119(a) on Patent Application No. 2018- 236571 filed in Japan on Dec. 18, 2018, the entire contents  of which are hereby incorporated by reference.  [0002]  This invention relates to a resist composition and a  patterning process using the composition.  [0003]  To meet the demand for higher integration density  and operating speed of LS Is, the effort to reduce the pattern  rule is in rapid progress. The logic devices used in smart  phones or the like drive forward the miniaturization tech› nology. Logic devices of 10-nm node are manufactured in a  large scale using a multi-patterning lithography process  based on ArF lithography.  [0004]  In the application of lithography to next 7-nm or  5-nm node devices, the increased expense and overlay  accuracy of multi-patterning lithography become tangible.  The advent of EUV lithography capable of reducing the  number of exposures is desired.  [0005]  Since the wavelength (13.5 nm) of extreme ultra› violet (EUV) is shorter than  ‰o of the wavelength (193 nm)  of ArF excimer laser, the EUV lithography achieves a high  light contrast, from which a high resolution is expectable.  Because of the short wavelength and high energy density of  EUV, an acid generator is sensitive to a small dose of  photons.  It  is believed that the number of photons available  with EUV exposure is  ‰4 of that of ArF exposure. In the  EUV lithography, the phenomenon that the edge roughness  (LWR) of line patterns or the critical dimension uniformity  (CDU) of hole patterns is degraded by a variation of photon  number is considered a problem.  [0006]  Aiming to reduce a photon number variation, an  attempt was made to render the resist more absorptive so that  the number of photons absorbed in the resist is increased.  [0007]  Patent Document 1 discloses a halogen-substituted  styrene base resin. Among the halogen atoms, iodine is  highly absorptive to EUV radiation of wavelength 13.5 nm.  Recently Patent Documents 2 to 4 propose to use iodine› substituted resins as EUV resist material. Regrettably, it is  not true that a higher sensitivity is obtainable merely by  incorporating iodine to increase the number of photons  absorbed. With respect to the acid generation in EUV  exposure, Non-Patent Document 1 reports that the acid  generation efficiency of iodized styrene is only 14% of that  of hydroxystyrene.  [0008]  The EUV lithography resist must meet high sensi› tivity, high resolution and low LWR at the same time. As the  acid diffusion distance is reduced, LWR is reduced, but  sensitivity becomes lower. For example, as the PEB tem› perature is lowered, the outcome is a reduced LWR, but a  lower sensitivity. As the amount of quencher added is  increased, the outcome is a reduced LWR, but a lower  sensitivity.  It  is necessary to overcome the tradeoff relation  between sensitivity and LWR.  It  would be desirable to have  [0023]  Preferably, the sulfonium or ammonium salt of  iodized benzene ring-containing carboxylic acid, the sulfo› nium or ammonium salt of iodized benzene ring-containing  N-carbonylsulfonamide, the iodized benzene ring-contain› ing amine, and the iodized benzene ring-containing ammo› nium salt have the following formulae (A)-1 to (A)-4,  respectively.  [0022]  In one aspect, the invention provides a resist com› position comprising an iodized base polymer, and at least  one quencher selected from the group consisting of a sul› fonium or ammonium salt of iodized benzene ring-contain› ing carboxylic acid, a sulfonium or ammonium salt of  iodized benzene ring-containing N-carbonylsulfonamide, an  iodized benzene ring-containing amine, and an iodized ben› zene ring-containing ammonium salt.  [0021]  The inventors have found that a resist composition  comprising an iodized polymer and a quencher selected  from a sulfonium or ammonium salt of iodized benzene  ring-containing carboxylic acid, a sulfonium or ammonium  salt of iodized benzene ring-containing N-carbonylsulfona› mide, an iodized benzene ring-containing amine, and an  iodized benzene ring-containing ammonium salt exhibits a  high sensitivity, low LWR, improved CDU, and wide pro› cess margin.  [0020]  An object of the invention is to provide a resist  composition which exhibits a high sensitivity, low LWR and  improved CDU independent of whether it is of positive tone  or negative tone, and a pattern forming process using the  same.  [0019]  For the acid-catalyzed chemically amplified resist,  it is desired to develop a resist composition providing a high  sensitivity and reducing LWR or improving CDU of hole  patterns.  a resist material having a high sensitivity and resolution as  well as improved LWR and CDU.  [0009]  Patent Document 5 proposes a quencher of iodo› nium carboxylate type having a carboxylate ion bonded to  an iodonium cation. Patent Documents 6 and 7 propose the  use of hypervalent iodine compounds as the quencher.  Patent Document 8 discloses a sulfonium salt of iodized  benzoic acid. Since iodine has a large atomic weight,  quenchers in the form of iodized compounds are fully  effective for suppressing acid diffusion.  [0010]  Patent Document  1:  JP-A 805-204157  [0011]  Patent Document 2: JP-A 2015-161823  [0012]  Patent Document 3: WO 2013/024777  [0013]  Patent Document 4: JP-A 2018-004812  [0014]  Patent Document 5: JP 5852490 (U.S. Pat. No.  9,176,379)  [0015]  Patent Document 6: JP-A 2015-180928 (U.S. Pat.  No. 9,563,123)  [0016]  Patent Document 7: JP-A 2015-172746 (U.S. Pat.  No. 9,448,475)  [0017]  Patent Document 8: JP-A 2017-219836  [0018]  Non-Patent Document 1: Jpn. J. Appl. Physics, Vol.  46, No. 7, pp. L142-L144, 2007 