(12) United States Patent (10) Patent No.: US 6,232,417 B1 Rhodes Et Al

USOO6232417 B1 (12) United States Patent (10) Patent No.: US 6,232,417 B1 Rhodes et al. (45) Date of Patent: May 15, 2001 (54) PHOTORESIST COMPOSITIONS FOREIGN PATENT DOCUMENTS COMPRISING POLYCYCLIC POLYMERS WITH ACID LABILE PENDANT GROUPS O789278 8/1997 (EP). 0836119 4/1998 (EP). 5297591 11/1993 (JP). (75) Inventors: Larry F Rhodes, Silverlake; Andrew 9230595 9/1997 (JP). Bell, Lakewood; Saikumar Jayaraman, Cuyahoga Falls, OTHER PUBLICATIONS John-Henry Lipian, Broadview Heights; Brian L. Goodall, Akron; J. V. Crivello et al., Chemically Amplified Electron-Beam Photoresists, Chem. Mater, 1996, 8,376-381. it. Shick, Strongsville, all of Louis A. Cappino et al., Novel Carboxylic Acid and Car boxamide Protective Groups Based on the Exceptional Sta (73) Assignee: The B. F. Goodrich Company, bilization of the Cyclopropylmethyl Cation, J. Org. Chem. 1995, 60, 7718. T719. Brecksville,reCKSVIIIe, OH (US)(US Patents wr’sAbstracts of Japan, vol. 018, No. 096 (P-1694), Feb. (*) Notice: Subject to any disclaimer, the term of this 16, 1994. patent is extended or adjusted under 35 Robert G. Gastinger et al., IL-Arene Complexes of Nickel U.S.C. 154(b) by 0 days. (II). Synthesis (from Metal Atoms) of (T-Arene)bis(pen tafluorophenyl)nickel(II). Properties, C-Arene Lability, and (21) Appl. No.: 08/928,573 Chemistry, J. Am. Chem. Soc., 1980, 102, 4959–4966. y - - - 9 (22) Filed: Sep. 12, 1997 Primary Examiner Donald R. Wilson e - as ASSistant Examiner-Caixia Lu (51) Int. Cl." ........................................................ C08F 4/80 (74) Attorney, Agent, or Firm Thoburn T. Dunlap (52) U.S. Cl. .......................... 526/171; 526/283; 526/308;526/309 (57) ABSTRACT (58) Field of Search ..................................... 526/283, 171, The present invention relates to a radiation Sensitive photo 526/308, 309 resist composition comprising a photoacid initiator and a polycyclic polymer comprising repeating units that contain (56) References Cited pendant acid labile groups. Upon exposure to an imaging radiation Source the photoacid initiator generates an acid U.S. PATENT DOCUMENTS which cleaves the pendant acid labile groups effecting a 4,491,628 1/1985 Ito et al. polarity change in the polymer. The polymer is rendered 5,155,188 10/1992 Goodall et al.. Soluble in an aqueous base in the areas exposed to the 5,372,912 12/1994 Allen et al.. imaging Source. The polymer repeating units are polymer 5,399,647 3/1995 Nozaki. ized from polycyclic monomers in the presence of Single or 5,468.819 11/1995 Goodall et al.. multicomponent catalyst Systems containing a Group VIII 5,585,219 12/1996 Kaimoto et al.. 5,585,222 12/1996 Kaimoto et al.. metal 5,705,503 1/1998 Goodall et al. 5,843,624 12/1998 Houlihan et al.. 13 Claims, 3 Drawing Sheets U.S. Patent May 15, 2001 Sheet 1 of 3 US 6,232,417 B1 Figure 1 U.S. Patent May 15, 2001 Sheet 2 of 3 US 6,232,417 B1 Figure 2 U.S. Patent May 15, 2001 Sheet 3 of 3 US 6,232,417 B1 Figure 3 US 6,232,417 B1 1 2 PHOTORESIST COMPOSITIONS ceSSes Suffer because of the undesirable environmental and COMPRISING POLYCYCLIC POLYMERS Safety ramifications. WITH ACID LABILE PENDANT GROUPS Various “dry” processes have been developed to over come the drawbacks of the wet chemical process. Such dry BACKGROUND OF THE INVENTION processes generally involve passing a gas through a chamber 1. Technical Field and ionizing the gas by applying a potential acroSS two The present invention is related to polycyclic polymers electrodes in the presence of the gas. The plasma containing and methods for their use as photoresists in the manufacture the ionic Species generated by the potential is used to etch a of integrated circuits. More Specifically, the invention is Substrate placed in the chamber. The ionic Species generated directed to photoresist compositions comprising a polycy in the plasma are directed to the exposed Substrate where clic polymer and a cationic photoinitiator. The polycyclic they interact with the Surface material forming volatile polymer contains recurring acid labile groups that are pen products that are removed from the Surface. Typical dant from the polymer backbone. The acid labile groups can examples of dry etching are plasma etching, Sputter etching be selectively cleaved to form recurring polar groups along and reactive ion etching. the backbone of the polymer. The polymers are transparent 15 Reactive ion etching provides well defined vertical Side to Short wave lengths of imaging radiation and exhibit wall profiles in the substrate as well as substrate to substrate resistance to reactive ion etching. etching uniformity. Because of these advantages, the reac 2. Background tive ion etching technique has become the Standard in IC Integrated circuits (ICs) are paramount in the manufac manufacture. ture of an array of electronic devices. They are fabricated Two types of photoresists are used in the industry, nega from the Sequential formation of alternating and intercon tive and positive photoresists. Negative resists, upon expo necting bands of conductive, Semiconductive and noncon Sure to imaging radiation, polymerize, crosslink, or change ductive layers on an appropriate Substrate (e.g., Silicon Solubility characteristics Such that the exposed regions are wafer) that are Selectively patterned to form circuits and 25 insoluble to the developer. UneXposed areas remain Soluble interconnections to produce Specific electrical functions. and are washed away. Positive resists function in the oppo The patterning of ICS is carried out according to various Site way, becoming Soluble in the developer Solution after lithography techniques known in the art. Photolithography exposure to imaging radiation. employing ultraViolet (UV) light and increasingly deep UV One type of positive photoresist material is based upon light or other radiation is a fundamental and important phenol-formaldehyde novolac polymers. A particular technology utilized in the production of IC devices. A example is the commercially utilized Shipley AZ1350 mate photosensitive polymer film (photoresist) is applied over the rial which comprises an m-creSol formaldehyde novolak wafer Surface and dried. A photomask containing the desired polymer composition and a diazoketone (2-diazo-1-napthol patterning information is then placed in close proximity to 5-Sulphonic acid ester). When exposed to imaging radiation, the photoresist film. The photoresist is irradiated through the 35 the diaZOketone is converted to a carboxylic acid, which in overlying photomask by one of Several types of imaging turn converts the phenolic polymer to one that is readily radiation including UV light, e-beam electrons, X-rays, or Soluble in weak acqueous base developing agent. ion beam. Upon eXposure to radiation, the photoresist under U.S. Pat. No. 4,491,628 to Ito et al. discloses positive and goes a chemical change with concomitant changes in Solu negative photoresist compositions with acid generating pho bility. After irradiation, the wafer is Soaked in a Solution that 40 toinitiators and polymers with acid labile pendant groups. develops (i.e., Selectively removes either the exposed or Because each acid generated causes deprotection of multiple unexposed regions) the patterned images in the photosensi acid labile groups this approach is known as chemical tive polymer film. Depending on the type of polymer used, amplification which Serves to increase the quantum yield of or the polarity of the developing Solvent, either the exposed the overall photochemical process. The disclosed polymers or noneXposed areas of film are removed in the developing 45 include Vinylic polymerS Such as poly Styrenes, process to expose the underlying Substrate, after which the polyvinylbenzoates, and polyacrylates that are Substituted patterned exposed or unwanted Substrate material is with recurrent pendant groups that undergo acidolysis to removed or changed by an etching process leaving the produce products that differ in Solubility than their precur desired pattern in a functional layer of the wafer. Etching is Sors. The preferred acid labile pendant groups include accomplished by plasma etching, Sputter etching, and reac 50 t-butyl esters of carboxylic acids and t-butyl carbonates of tive ion etching (RIE). The remaining photoresist material phenols. The photoresist can be made positive or negative functions as a protective barrier against the etching process. depending on the nature of the developing Solution Removal of the remaining photoresist material gives the employed. patterned circuit. Trends in the electronics industry continually require ICS In the manufacture of patterned IC devices, the processes 55 that are faster and consume less power. To meet this speci of etching different layers on the wafer are among the most fication the IC must be made Smaller. Conducting pathways crucial Steps involved. One method is to immerse the (i.e., lines) must be made thinner and placed closer together. Substrate and patterned resist in a chemical bath which The Significant reduction in the size of the transistors and the attacks the exposed Substrate Surfaces while leaving the lines produced yields a concomitant increase in the effi resist itself intact. This “wet' chemical process suffers from 60 ciency of the IC, e.g., greater Storage and processing of the difficulty of achieving well defined edges on the etched information on a computer chip. To achieve thinner line Surfaces. This is due to chemical undercutting of the resist widths, higher photoimaging resolution is necessary. Higher material

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