The properties and thermal stability of porous organic low-dielectric-constant films (version 8 and version 9) have been studied in this research. These porous films were obtained by spin coating, followed by baking and furnace curing. Both porous films exhibit very low dielectric constants of only approximately 2.1 and good physical and electric properties. Thermal decomposition and further shrinkages occur in these as-cured films during heat treatments, indicating the release of residual poragens and some structural changes of these films; whereas the properties of the version 9 porous organic films remain at the same levels after heat treatments and exhibit better thermal stability. Residual compressive stresses of approximately 40 MPa exist in both films and decrease after heat treatments, revealing some film degradation and stress relaxation. (C) 2004 Elsevier B.V. All rights reserved.