Synthesis Of Matrix Resin For Chemical Amplified Photoresist And Their Performance Study

The chip industry as a strategic industry involves the national economy and national security.In 2018,the chip imports reached more than 312 billion dollars,which is far more than crude oil.More efforts have been focused on semiconductor chip industry because of the ZTE incident and the Japan-Korea trade war.Chips are mainly manufactured through lithography,doping,etching,packaging and testing.Lithography is the core process in semiconductor manufacturing process,and the photoresist as a key material in the photolithography process is used to transfer the pattern to substrate through exposure and development.As a strategic material,photoresist is monopolized by foreign companies,which greatly limits the development of China’s chip industry.The film-forming resin as the bakebone component of photoresist which determines the performance of the photoresist.In this dissertation,serious of film-forming resin are designed and synthesized,and the effect of resin structure and synthesis process on the performance of photoresist are studied.The work in this dissertation includes the following parts:(1)Synthesis of linear polymer and its application in photoresistPoly(TBA-CA-St-ASM)(PTCSA)were synthesized by using tert-butyl acrylate(TBA),styrene(St),p-acetoxy styrene(ASM),and cedryl methacrylate(CA)as co-monomer via precipitation polymerization.Then,Poly(TBA-CA-St-HS)(PTCSH)were prepared by hydrolysis reaction in the presence of sodium methoxide in methanol.The FT-IR and ~1H-NMR spectra were used to characterize the structure of the polymer.The effects of monomer ratio,system solid content and initiator amount on the molecular weight and T_g of the polymer were investigated.The results show that the molecular weight of the polymer increases with increasing the solid content;the molecular weight decrease with increasing the amount of initiator increases;the T_g of the polymers increases with increasing the CA feed ratio.The effect of the factors,such as CA structural units,photoacid generator,and the photolithography process on the sensitivity and resolution of photoresist were studied,and the composition of photoresist and process conditions were optimized.KrF photoresist were prepared by mixing PTCSH(ASM:TBA:CA:St=6:1:1:2,Mw=11970 g/mol,PDI=1.69)with 3.3%of DTBPI-CS,and the resolution is 0.25μm.I-line photoresist was prepared by using PTCSH as the matrix resin,NHNI-TF as PAG,the aspect ratio reached 4.(2)Preparation of star polymer and its lithography performanceWell-defined star copolymers were synthesized through RAFT polymerization methodologies with ASM,TBA,initiator AIBN and star RAFT agent CTA.The molecular weight,polydispersity index,and intrinsic viscosity of the polymers were obtained using triple detection size exclusion chromatography.The zimm branching factor g′was lower than 1 which confirmed the formation of star polymers.The effects of CTA agent and monomer concentration on the polymer molecular weight and branching degree were studied.The results show that with the loading of CTA increases,the molecular weight and viscosity of the polymer decrease,the molecular weight distribution becomes narrower,and the T_g decreases.With the monomer concentration increases,the molecular weight and T_g of the polymer increase.The thermal properties and lower absorbance at 248 nm of the polymers indicated that the polymer was suitable for using as KrF photoresist.Moreover,the photolithography performance of the photoresist based on star polymer BPHT4(8600g/mol,PDI=1.46)with DTBPI-CS was evaluated using KrF laser exposure system;the results indicated that the resolution reach 0.2μm at 12 mJ/cm~2 under the conditions:soft bake 90℃,60 s,post exposure bake 130℃×90 s.(3)Synthesis of polymer containing photoacid generator unitsTerpolymer PATS(non-ionic type)and PATT(ionic type)were obtained by using ASM,TBA and photoacid-generating monomers through free radical copolymerization.FT-IR and ~1H-NMR spectra were used to characterize the structure of the polymers.The effect of photoacid-generating units on the molecular weight,residual carbon content and dissolution in solvents of the polymers were investigated.The results show that with the increase of photoacid-generating units,the molecular weight and the amount of residual carbon increases,and PATS has an excellent solubility,whereas the solubility of PATT became weaker.The hydrolysis behavior of two types of polymers was also studied,the results show that the imide ring of PATS undergoes a ring-opening reaction with sodium methoxide,and PATT become insoluble in common solvents after hydrolysis.PATS and PATT were dissolved in solvent to prepare photoresist.The sensitivity,contrast and the adhesion of photoresist were tested.The results show that the photoresist based on PATS and PATT is slower than the photoresist based on polymer-blend-PAG,and acetoxy group leads to lower adhesion between photoresist and the substrate,resulting in peeling of the photoresist.New copolymers based on St and TBA were synthesized to decrease the hydrophobic effect of acetoxy group,and the resolution of the photoresist reached 0.27μm.(4)The property and performance of single-component molecular glass photoresist materialsTPPA-t-BOC were synthesized through the reaction of TPPA and di-tert-butyldicarbonate(DBDC)at room temperature.FT-IR,~1H-NMR,XRD,and TGA were used to characterize the structure and properties of TPPA-t-BOC.The effect of t-BOC content on the solubility,heat resistance and film retention rate of TPPA-t-BOC was investigated.The results showed that with the increase of t-BOC grafting rate,the solubility of molecular glass decreased,the heat resistance and retention rate increased.Then,TPPA-t-BOC-PAG were obtained through the reaction of TPPA-t-BOC with 4-(2-bromoethyl)benzenesulfonate sodium and triphenylsulfonium chloride benzenesulfonic.FT-IR,~1H-NMR,XPS,TGA were used to characterize the structure and properties of TPPA-t-BOC-PAG.The photoresist was prepared by dissolving TPPA-t-BOC-PAG and additivites in solvent.The effect of the ratio between t-BOC and PAG unit and post exposure bake temperature on sensitivity and film retention rate of photoresist were tested.The acid diffuse length properties and patterning performance of the single-component molecular glass resist is discussed,showing a resolution of 0.25mm.In conclusion,series of different structure of film forming resins were synthesized,and photoresist based on these film forming resins were prepared.The effect of different reaction conditions on the properties of film forming resin were studied.The effect of molecular structure and property on the performance of photoresist were aslo analyzed.