Poly(Methyl Methacrylate‐Isobutylene) Copolymers as Highly Sensitive Electron Beam Resists

Gipstein, Edward; Moreau, Wayne M.; Need, Omar U.

doi:10.1149/1.2133004

Cited by 13 publications

(3 citation statements)

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“…The AD–SD type copolymers presented various T g -composition dependences. For example, lMMA–VDC copolymers show positive deviation behavior, while MMA–IB copolymers show negative deviation in a certain composition range, as shown in Figure a. According to the previous discussion, it is expected that dynamic rigid structures existing in the AD-type monomer sequence will be destroyed by copolymerization, so the negative deviation should be observed in the high AD-type content region.…”

Section: More Complex Casesmentioning

confidence: 99%

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Glass Transition Temperatures of Copolymers: Molecular Origins of Deviation from the Linear Relation

Huang

Zhang

et al. 2022

Macromolecules

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The glass transition temperature (T g) is an important material parameter in determining polymer properties. The main molecular structure factors affecting T g are chain stiffness and cohesive energy, causing polymers to exhibit the complex micro-structure dependence of T g. The composition dependence of the T gs of binary random copolymers mainly shows as three cases: the linear relation, the negative deviation (or concave curve), or the positive deviation (convex curve). The study of the T g’s composition dependence can guide the design of copolymer materials with desirable properties. On the other hand, it can provide insights into understanding the precise nature of the glass transition. In this study, the root cause of the T g deviation from the linear relation in random copolymers was revealed, and new molecular origins were proposed. First, the theoretical basis of why there exists a linear T g relation for copolymers was clarified, and the influence of the specific polar interactions between components was discussed briefly. More importantly, it has been identified that the negative T g deviation is related to copolymers composed of the mono-substituted (M-type) monomer and asymmetrical di-substituted (AD-type) monomer, and the positive T g deviation is related to copolymers composed of the M-type monomer and symmetrical di-substituted (SD-type) monomer. The molecular origin of the T g deviations from the linear relation is the destruction of the special conformational structures (e.g., the locally rigid conformational structure in the AD-type homopolymer or the dynamic flexible structure in the SD-type homopolymer) caused by copolymerization. The behaviors for more complex binary copolymers (AD–AD, SD–SD, and AD–SD types) were also discussed. Finally, the variation in T g of a statistical copolymer as a function of composition was summarized.

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Section: More Complex Casesmentioning

confidence: 99%

“…Glass transition temperature and compositions of (a) MMA–VDC copolymers (data from ref ) and MMA–IB copolymers (data from ref ) and (b) αMS–IB copolymers (data from ref ).…”

Section: More Complex Casesmentioning

confidence: 99%

Glass Transition Temperatures of Copolymers: Molecular Origins of Deviation from the Linear Relation

Huang

Zhang

et al. 2022

Macromolecules

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“…The sensitivity is also improved by copolymerization with highly radiation susceptible groups. Acrylonitrile (2), isobutylene (3), methacrylic acid (4), and a-chloromethacrylate (5) were incorporated into PMMA. On the other hand, polymers of methacrylic esters (4) and methacrylic esters containing halogens (6) were reported as making a more highly sensitive positive electron resist than PMMA.…”

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confidence: 99%

Polymers Constituted by Methyl Methacrylate, Methacrylic Acid, and Methacryloyl Chloride as a Positive Electron Resist

Kitakohji¹,

Yoneda²,

Kitamura³

et al. 1979

J. Electrochem. Soc.

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Mixture systems of copolymer of methyl methacrylate-methacrylic acid P(MMA-MA) and terpolymer of methyl methacrylate-methacrylic acid-methacryloyl chloride P (MMA-MA-C1MA) have been synthesized and investigated as a positive electron resist. These resists form intermolecular acid anhydride bonds after baking, resulting in improved sensitivity and thermal stability while maintaining high resolution as compared with poly(methyl methacrylate). The polymer containing 5 mole percent (m/o) methacrylic acid (MA) and 0.5 m/o methacryloyl chloride (C1MA) has a sensitivity of 1.9 • 10 -5 C/cm2 at an accelerating voltage of 30 kV, a thermal stability even above 140~ The sensitivity of the polymer containing 0.36 m/o C1MA is 8 • 10 -8 C/cm 2, which is 20 times that of PMMA.Electron beam lithography has been widely investigated and accepted as a means of fabricating microelectronic devices. Properties such as electron sensitivity, resolution, thermal stability, and process tolerance are important factors in determining resist performance. In general, a positive resist has higher resolution than a negative resist which conversely has poor resolution.Many investigations have been carried out to improve the sensitivity of a positive resist while maintaining the other properties. Poly(methyl methacrylate), PMMA, is widely used, but its sensitivity is insufficient. The sensitivity of PMMA, which is fractionated in a mixture of methyl isobutyl ketone (MIBK) and isopropyl alcohol (IPA) to obtain high molecular weight materials with low dispersivity, and developed in a fractional solvent, is better than that of unfractionated or standard-developed PMMA (1). The sensitivity is also improved by copolymerization with highly radiation susceptible groups. Acrylonitrile (2), isobutylene (3), methacrylic acid (4), and a-chloromethacrylate (5) were incorporated into PMMA. On the other hand, polymers of methacrylic esters (4) and methacrylic esters containing halogens (6) were reported as making a more highly sensitive positive electron resist than PMMA. These highly sensitive resists, however, will not be so thermostable as PMMA.To obtain higher sensitivity and thermal stability than methacrylic esters such as PMMA, polymers incorporating methacrylic acid and methacryloyl chloride were synthesized and evaluated. These polymeric resists will form intermolecular anhydride bonds after heating. Polymeric resist, which is cross-linked by anhydride bridges among methacrylate chains, has been shown to have advantageous properties such as higher sensitivity and thermal stability than PMMA in cross-linked methacrylic esters such as ethyl-, isobutyl-, cyclohexyl-, etc. methacrylate. This modified type methyl methacrylate resist is reported by Roberts (7). It has greater thermal stability than PMMA, but the electron sensitivity is not much improved. The sensitivity obtained by MIBK development is 6-8 • 10-6 C/cm 2 at 10 kV after baking at 115~ for 30 min. Measured at 30 kV, the sensitivity is roughly estimated to be 2 X 10-~ C/cm 2 (8).We have examined...

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Studies of methyl methacrylate‐methyl α‐chloroacrylate, copolymers and poly(methyl α‐chloroactylate) as electron sensitive positive resists

Lai

Shepherd

Ulmer

et al. 1977

Polymer Engineering & Sci

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Poly(methyl α‐chloroacrylate) (PMCA) and the copolymers of methyl methacrylate and methyl α‐chloroacrylate (poly(MMA‐co‐MCA)) have been reported recently to be more susceptible to radiation degradation than poly(methyl methacrylate) (PMMA). In this paper we report our studies of PMCA and poly(MMA‐co‐MCA) as electron‐sensitive positive resists. It has been found that both PMCA and the copolymers are more sensitive than PMMA. Using mixtures of dimethylformamide and 2‐propanol as developers, the sensitivities of PMCA and poly(MMA‐co‐MCA) (38 mole percent MCA) have been found to be 1 × 10−5 and 6 × 10−6 coulomb/cm2, respectively. It has also been found that crosslinking predominates in PMCA when the electron dose exceeds 6 × 10−4 coulomb/cm2.

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Poly(Methyl Methacrylate‐Isobutylene) Copolymers as Highly Sensitive Electron Beam Resists

Cited by 13 publications

References 1 publication

Glass Transition Temperatures of Copolymers: Molecular Origins of Deviation from the Linear Relation

Glass Transition Temperatures of Copolymers: Molecular Origins of Deviation from the Linear Relation

Polymers Constituted by Methyl Methacrylate, Methacrylic Acid, and Methacryloyl Chloride as a Positive Electron Resist

Studies of methyl methacrylate‐methyl α‐chloroacrylate, copolymers and poly(methyl α‐chloroactylate) as electron sensitive positive resists

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