Multiple trigger photoresist compositions and methods

#The present invention relates to novel negative-type photoresist compositions and methods of using them. The invention further relates to multiple trigger photoresist processes which allow for improvement in contrast, resolution, and/or line edge roughness in some systems without giving up sensitivity. The photoresist compositions and the methods of the current disclosure are ideal for fine pattern processing using, for example, ultraviolet radiation, extreme ultraviolet radiation, beyond extreme ultraviolet radiation, X-rays and charged particle rays exposure.

#As is well known in the industry, the manufacturing process of various kinds of electronic or semiconductor devices such as ICs, LSIs and the like involves a fine patterning of a resist layer on the surface of a substrate material such as a semiconductor silicon wafer. This fine patterning process has traditionally been conducted by the photolithographic method in which the substrate surface is uniformly coated with a positive or negative tone photoresist composition to form a thin layer of the photoresist composition and selectively irradiating with actinic rays (such as ultraviolet light) through a photomask followed by a development treatment to selectively dissolve away the photoresist layer in the areas exposed or unexposed, respectively, to the actinic rays leaving a patterned resist layer on the substrate surface. The thus obtained patterned resist layer is utilized as a mask in the subsequent treatment on the substrate surface such as etching, plating, chemical vapor deposition and the like. The fabrication of structures with dimensions of the order of nanometers is an area of considerable interest since it enables the realization of electronic and optical devices which exploit novel phenomena such as quantum confinement effects and allows greater component packing density. Thus, the resist layer is required to have an ever-increasing fineness. One method which can be used to accomplish this is by using actinic rays having a shorter wavelength than the conventional ultraviolet light, such as, for example, electron beams (e-beams), excimer laser beams, EUV, BEUV and X-rays, used as the short wavelength actinic rays. Needless to say, the minimum size obtainable is primarily determined by the performance of the resist material and the wavelength of the actinic rays. Various materials have been proposed as suitable resist materials.

#Many positive photoresists they generally apply a technique called “chemical amplification” to the polymeric resist materials. A chemically amplified resist material is generally a multi-component formulation in which there is a main polymeric component, such as a novolac resin which contributes towards properties such as resistance of the material to etching, mechanical stability and developability; and one or more additional components which impart desired properties to the resist and a photoacid generator. Typically, a portion of the hydroxy groups of a phenolic polymer, such as a novolac, a polyhydroxystyrene and the like, is protected by a functional group which reacts with an acid and is removed to de-protect the hydroxy group making the hydroxy group available for other reactions, which in positive photoresists is developability. By definition, the chemical amplification occurs through a catalytic process involving the sensitizer which results in a single irradiation event causing a cascading effect by reacting with multiple functional groups of the protected novolac molecules. In a typical example the resist comprises a polymer and a photoacid generator (PAG) as sensitizer. The PAG releases a proton in the presence of actinic radiation (light or e-beam). This proton then reacts with the polymer to cause it to lose the functional group thus deprotecting the hydroxy group. In the process, a second proton is generated which can then react with a further molecule.

#FIG. 1: shows SEM images of (a) PHOST 1 and (b) PBOCST 1 resist patterns after 30 keV electron beam exposure.

#FIG. 2: shows SEM images of electron beam exposed 60 nm pitch lines in PHOST 2 (top) and PBOCST 2 (bottom) resists with various doses. 30 keV electron beam was used for patterning. The critical dimension (CD) values are shown in the individual images. Scale bar: 200 nm.

#FIG. 3: shows SEM images of EUV exposed 44 nm pitch lines patterned in PHOST 2 (top) and PBOCST 2 (bottom) resists with various doses. The dose-to-wafer details are shown in the individual images. Scale bar: 200 nm.

#In a first embodiment, a multiple trigger negative-working photoresist composition is disclosed comprising a) at least one polymer, oligomer or monomer, each comprising two or more crosslinkable functionalities, wherein essentially all the functionalities are attached to acid labile protecting groups, b) at least one acid activated crosslinker, and c) at least one photoacid generator.

#In a second embodiment, the multiple trigger photoresist composition of the above embodiment is disclosed, wherein at least about 90% of the crosslinkable functionalities are attached to acid labile protecting group.

#In a third embodiment, a multiple trigger photoresist composition of the above embodiments is disclosed, wherein the acid-labile protecting group is capable of being removed when exposed to acid under ambient conditions providing a functionality capable of crosslinking with the crosslinking system when the crosslinking system is catalyzed by acid.