US 2020/0319555 Al  1  Oct. 8, 2020  NEGATIVE RESIST FORMULATION FOR  PRODUCING UNDERCUT PATTERN  PROFILES  FIELD OF INVENTION  BACKGROUND  [0012]  There is a need for a high sensitivity i-line chemi› cally amplified negative resist which gives, during imaging,  [0007]  However, applications, such as processing of GaAs  or compound III-V substrates, light emitting diodes (LED),  high powered LED and organic light emitting diodes  (OLED), on the other hand, largely are still employing  [0006]  The major development in resist products and  chemistry has been devoted to the silicon integrated circuit  (IC) chip industry. This technology moved from i-line  lithography to shorter wave length ( deep UV) lithographies,  such as 248 nm, 193 nm and 157 nm in quest for higher  resolution. Several generations of advanced deep UV resist  materials have been developed. Critical dimensions (CD)  well below 0.2 µmare  achieved in production, applying 248  and 193 nm lithography based on chemically amplified  resists.  [0005]  The use of a negative-working, acid-sensitive pho› toresist composition is known in the prior art. Most of such  prior art photoresist compositions use a crosslinking agent  that reacts with the polymeric binder resin to form an  insoluble film comprising a higher molecular weight poly› mer  [0011]  Using a pattered resist, either CVD or sputtering  metal may be employed to metalize areas of substrate not  covered by resist. However, subsequent to this step the  remaining resist can be removed by either employing a  chemical etchant or an adhesive tape applied to the surface  of the resist to remove it. In either situation removal may be  facilitated by employing a lift-off process is employed where  the resist patterns were initially produced prior to metalli› zation have an undercut at the resist substrate interface. In  the case where a chemical etchant is employed, such as a  stripper, removal of remaining resist is made easier because  the undercut portion of the resist is not metallized allowing  the stripper to attack the resist and remove it. Straight wall,  resist profiles, and profiles with a poor undercut have  significant metallization at the sidewalls of these profiles  making removal of the resist with a stripper much more  difficult or impossible. Similarly, when using a sticky tape  approach to affect removal of the resist, the more pro› nounced the undercut of the profiles the easier these are to  remove without leaving large amount of residual resist on  the substrate. The minimization of this residue, in tum,  allows for a faster removal of this residue in subsequent  stripping operation. Traditional, approaches to getting  sloped profiles which have some undercut resist character› istics for lift-off application, have depended upon the  manipulation of optical conditions during exposure such as  exposure tool defocus. Such "optical" approaches are inher› ently limited by the optical physics itself, in the extent of  undercut which is possible.  [0004]  There are two types of photoresist compositions,  negative-working and positive-working. When negative› working photoresist compositions are exposed image-wise  to radiation, the areas of the resist composition exposed to  the radiation become less soluble to a developer solution  (e.g. a cross-linking reaction occurs) while the unexposed  areas of the photoresist coating remain relatively soluble to  such a solution. Thus, treatment of an exposed negative› working resist with a developer causes removal of the  non-exposed areas of the photoresist coating and the cre› ation of a negative image in the coating, thereby uncovering  a desired portion of the underlying substrate surface on  which the photoresist composition was deposited.  [0010]  CVD metal deposition occurs by reaction of a  reactive gas under reduced pressure with a either the semi› conductor substrate, itself or by reaction with a second  reactive gas producing in both scenarios a metal deposit. For  instance, as non-limiting examples, in the first scenario WF $_{6 }$ may affect deposition on a Silicon substrate by reaction with  Si to produce a metallic W deposits and producing as a  reaction product gaseous SiF $_{6 }$ which is pumped away. An  example of the second scenario is the gaseous reaction of  WF $_{6 }$ with H$_{2 }$ to deposit metallic W and producing as a  reaction product gaseous HF which is pumped away.  [0003]  This radiation exposure causes a chemical trans› formation in the exposed areas of the coated surface. Visible  light, ultraviolet  (UV) light, electron beam and X-ray radiant  energy are imaging radiation types commonly used today in  microlithographic processes. After this image-wise expo› sure, the coated substrate is treated with a developer solution  to dissolve and remove either the radiation-exposed or the  unexposed areas of the coated surface of the substrate.  [0002]  Photoresist compositions are used in microlitho› graphic processes for making miniaturized electronic com› ponents such as in the fabrication of computer chips and  integrated circuits. Generally, in these processes, a thin film  of a photoresist composition is first applied to a substrate  material, such as silicon wafers used for making integrated  circuits. The coated substrate is then baked to evaporate  solvent in the photoresist composition and to fix the coating  onto the substrate. The baked, coated surface of the substrate  is next subjected to an image-wise exposure to imaging  radiation.  [0009]  Sputtering metal deposition is done in a vacuum  chamber where an electrically grounded metallic target  wafer is bombarded with electrically charged Argon gas,  sputtering away the metal atoms and depositing them on a  target wafer.  [0008]  Electron beam physical vapor deposition, or  EBPVD, is a form of physical vapor deposition in which a  target anode is bombarded with an electron beam given off  by a charged tungsten filament under high vacuum. The  electron beam causes atoms from the target to transform into  the gaseous phase. These atoms then precipitate into solid  form, coating everything in the vacuum chamber (within  line of sight) with a thin layer of the anode material.  conventional i-line lithography and i-line resist materials  which are not chemically amplified. For these applications  Deposition of metal ( a.k.a. metallization) on semiconductor  substrates covered with a pattered photoresist is frequently  done by chemical vapor deposition (CVD) technologies  such as LPCVD. Sputtering metal deposition may also be  employed to deposit thick, uniform metal layers. Another  technique employed for metallization is Vacuum Deposition  (VD), in particular as induced bye-beam (EBPVD).  [0001]  The field of the invention pertains to a negative  radiation-sensitive aqueous base soluble photoresist compo› sition used for making integrated circuit  (IC) and light  emitting diode (LED) Devices 