There are many considerations to the design of BARC materials. Among those many properties, one important property that can effect lithographic performance is BARC coating uniformity. In general, the basic coating property (conformal or planar) depends on basic characteristics of polymer (Mw, chemistry, etc). But another major factor to control the coating uniformity is the choice of solvent system in the formulation of the BARC. According to our experimental results, two major factors that can affect the coating uniformity of one BARC are the vapor pressure and the hydrophilicity of solvents. If any solvent has too high vapor pressure and high hydrophilicity relatively, polymer segregation occurs in BARC surface area in case of high humidity condition, resulted in bad coating uniformity.
In this paper, we will show basic evaluation results including the morphology change of BARC surface with several solvents which can be used in BARC formulation according to various humidity and temperature conditions. And also we will show the solution to overcome this problem in device manufacturing.
We have developed several COMA (Cycloolefin-maleic anhydride) type resists and demonstrated their good lithographic performances, especially in the isolated line. Our resist (DHA-H110) was newly upgraded for the manufacturing of sub-100nm device in terms of bulk slope, LER (Line Edge Roughness), CD Linearity, and matching with substrate to prevent pattern collapse. The chemical structure of base resin was almost unchanged. The bulk slope resulted from high absorbency of the matrix resin was successfully overcome by introducing new additive, S1, which is an agent to remove not only top loss but also footing in the bottom. In real device application, DHA-H110 exhibits better adhesion and smaller LER than acrylate type resists on organic BARC. In addition, it shows superior pattern profile after etch process to acrylate type resists. In this paper, we suggest resist related issues for sub-100nm patterning and present lithographic performances of DHA-H110 in detail.
Application of a top surface imaging process by silylation (TIPS) to ArF excimer lithography is desirable for ULSI production with minimum feature size below 0.12micrometers . It provides high etch resistance and controls non-uniform reflectivity in the multiple film layers over topography and shows superior characteristics in terms of adhesion and resist pattern collapse compared with single layer resist process of wet development. The processes for top surface imaging have been improved by many groups, however, the design of photoresist for TIPS in 193nm lithography has been considerably limited due to its characteristics like energy sensitivity, silylation selectivity. Positive-tone chemically amplified TSI resist of crosslinking type is more appropriate for sub-100nm lithography in consideration of adhesion and resist rigidity. A new class of positive phororesist containing polyvinylphenol and novel acetal type crosslinker of poly(3,3'-dimethoxypropene) was developed for 193nm top surface imaging process by silylation. This new resist containing acetal type crosslinker is quite different with those practiced in traditional DUV and ArF lithography. Novel crosslinker was synthesized from polyacrolein with a yield of 90%. And then the silylation properties and lithography performances of the resist were investigated for 193nm top surface imaging process using gas-phase 1,1,3,3- tetramethyl disilazane(TMDS) as a silylating agent. The minimum pattern size of 0.12micrometers L/S was defined after dry development at a sensitivity of 2 mJ/cm2 with annular illumination using ArF microstepper having 0.60 NA. In this paper, the material characteristics of novel resist containing acetal type crosslinker of poly(3,3'- dimethoxypropene) and lithographic performances is reported for 193nm top surface imaging process by silylation.
The compatibility of novel organic bottom anti-reflective coatings (BARC), HEART003 and HEART004 developed by Hyundai Electronics, with various chemically amplified resists (CAR) was reported. The incompatibility between organic BARC and CARs is caused by the differences of residual activity on the surface of organic BARC after baking process and the types of dissolution inhibitors in the polymer of CAR and photo acid generators (PAG) used in their formulation. In KrF lithography, the HEART003 was much compatible with acetal type resist than annealing type resist because it's neutral acidity on the surface of BARC. The incompatibility with annealing type resist was caused by weak residual acidity on the surface of BARC, relatively. Thus we tried to adjust the feasible residual acidity on the surface of BARC and optimum thermal baking condition. The modified HEART003 has excellent compatibility not only with acetal type resist, but also with annealing type resist in the same platform. In ArF lithography, the HEART004 has also good compatibility with cycloolefin type and (meth)acrylate type ArF resist by modification of its formulation.
In our previous model, we have introduced a lot of t- butylcarboxylate group in matrix resin to achieve a high contrast and obtain a good lithographic performance. Most ArF photoresists having only t-butylcarboxylate group as a dissolution inhibitor have showed by far the inferior performance in a poor amine controlled environment. To overcome this problem, we greatly reduced the usage of t-butyl carboxylate group and increased the amount of HMEBC that contains both carboxylic acid group and alcohol group. And also, we newly introduced acid labile cross-linker for high contrast. Our novel resist exhibited an excellent lithographic performance without any protective top coating material, namely, a good PED (post exposure delay) stability, an improved CD (Critical Dimension) linearity, a proper sensitivity for process, and a good contrast. In addition, its synthetic yield is very high (>50%) and then it is cost- effective for mass production. 120 nm patterns were successfully defined at 13 mJ/cm2 by using a BIM (Binary Intensity Mask) with 2/3 annular (0.50/0.75(sigma) ).
A chemically amplified resist containing a basic monomer, 3- (t-butoxycarbonyl)-1-vinylcaprolactam (BCVC), in the matrix polymer was synthesized with various monomer feed ratios. Diffusion and evaporation of photogenerated acid in the copolymer films were investigate for various fractions of the basic units in copolymers. It is found that only acid surviving deactivation by the BCVC units diffuses into unexposed areas and evaporates for the copolymer film to bleach the indicator film. Evaporation of a low molecular weight basic additive is also examined. Whereas the low molecular weight basic additive evaporated during baking, the basic monomer units in the copolymer did not evaporate at all due to covalent bonding to polymer backbone chain. Thus, the copolymer with the basic monomer can control the acid diffusion and evaporation effectively. The new resists system enables us to form fine patterns even after post- exposure delay of 2 h without any additional treatment.
A novel copolymer with alicyclic olefin moieties for an electron beam resist has been developed. In general, methacrylate copolymers widely used in the field of E-beam lithography show a low etch resistance due to their linear backbone structure. Our goal was to enhance an etch selectivity to various substrates while maintaining a high resolution. We designed alicyclic olefin copolymers with highly rigid backbone structures to improve the etch selectivity and synthesized a copolymer resin, poly(2- hydroxyethyl 5-norbornene-2-carboxylate/t-butyl 5- norbornene-2-carbolate/5-norbornene 2-carboxylic acid/maleic anhydride), which is formed with alicyclic units in their main chains. This alicyclic backbone structure of copolymer affords better etch selectivity to various substrates without sacrificing its resolution than those of other methacrylate copolymers. Etch selectivities have been studied for polysilicon, silicon dioxide, and tungsten substrates, respectively. Our resists showed the etch selectivities comparable to that of typical KrF resist for polysilicon substrate and comparable to those of typical novolac resist for silicon dioxide and tungsten substrates. The effect of photo acid generator to the electron beam lithographic performance was also investigated.
We have newly developed a novel multi-functional monomer. Application of this monomer also allows us to introduce another unit to further improve its etch resistance. Furthermore, our novel resist containing this multi- functional monomer exhibits an excellent adhesion to Si substrate, an improved CD linearity, a high sensitivity, a good contrast, and a high synthetic yield. A 110nm L/S pattern was successfully at 1:2 pitch of a strong PSM was also successfully obtained by using a 2.38wt percent TMAH aqueous solution as a developer.
In this paper we report here on lithographic performance of high resolution, environmentally stable and aqueous base developable positive tone resist for DUV lithography. There have been a lot of efforts to prevent the resist from suffering from the deactivation of acid during the delay time between exposure and post exposure bake (PEB). The new design of matrix resin containing amide functional group has advantages over current lithographic techniques. The effects of amide functional group as a basic additive in a chemically amplified resist was investigated. A new class of matrix resin containing amide functional group, poly(hydroxystyrene-co-t- butyl acrylate-co-3-(t-butoxycarbonyl)-1-vinyl-2-caprolactam), was developed. It showed 0.20 micrometer lines/spaces patterns of this resist using KrF excimer stepper (NA 0.55, partial coherence factor 0.55) with an exposure dose of 25 mJ/cm2. This resist showed no change of pattern profile after 2 hours post exposure delay in which ammonia concentration is 5 ppb. 3-(t-butoxycarbonyl)-1-vinyl-2-caprolatam (BCVC) unit as a basic additive can not only solve amine contamination effectively, but also improve the resolution of the resist. BCVC unit reduces the diffusion of acid and it results in sharp contrast at the interface between the exposed and unexposed areas. Therefore, adding BCVC unit in matrix resin leads to the stabilization of the pattern profile and higher resolution.
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