Hydrolysis and condensation of a benzocyclobutene-functionalized precursor for the synthesis of high performance low-K polymers

Abstract

The development of microelectronics requires high performance interlevel dielectric materials with an extremely low dielectric constant and loss factor. Benzocyclobutene (BCB)-based materials have attracted significant attention because of their low-dielectric constant, low loss factor, and excellent high-temperature performance. The Dow chemical company has developed a series of BCB photoresists for interlevel dielectrics based on 1,3-bis[2-(1,2-dihyd-benzocyclobutene-4-yl)vinyl]-1,1,3,3-tetramethyldisiloxane (DVS-BCB). However, the introduction of a BCB group to prepare BCB resins requires expensive noble metal catalysts such as Pd salts for the Heck reaction or Suzuki reaction. Herein, a simple but novel synthetic route for the hydrolysis and condensation of BCB-functionalized chlorosilane (BCS) to obtain 1,3-bis(1,2-dihydro-benzocyclobutene-4-yl)-1,3-dimethyl-1,3-divinyldisiloxane (DBDVS) was developed. Similarly, BCB-functionalized chlorosilane as the BCB precursor can also react with silanols or alcohols such as 1,3-adamantanediol to afford 1,3-bis[(1,2-dihydro-benzocyclobutene-4-yl)methylvinylsilyloxy]adamantane (AdaDBDVS), which provides a method for the BCB functionalization of hydroxyl-containing organic or inorganic surfaces. The cured DBDVS and AdaDBDVS exhibit high glass transition temperatures above 380 °C and good thermal stability (T_5% > 440 °C). Moreover, the crosslinking density of the cured DBDVS and AdaDBDVS is higher than that of the cured DVS-BCB. Thus, the cured DBDVS and AdaDBDVS exhibit better thermal mechanical properties such as higher modulus and higher glass transition temperature. In addition, the cured DBDVS exhibits a low CTE of 47.8 ppm per °C from 30 to 275 °C as well as an extremely low dissipation factor of 0.00045 at 1 MHz, which is lower than that of cured DVS-BCB.