A processor based method for measuring dimensional properties of a photoresist profile, the method comprising steps of: inputting photoresist and exposure parameters into a stochastic model of a photoresist process with the steps and of determining a number of acid generators and quenchers within a photoresist volume; determining a refractive index and irradiance of the photoresist volume; computing the photoresist profile from the stochastic model using the processor with the steps (18, 20, 22, 24, 28, 30, 32) of determining a number of photons absorbed by the photoresist volume; determining which one of a photolysis mechanism or an ionization mechanism is most appropriate and selecting either the photolysis mechanism or the ionization mechanism; determining (22, 24) a number of the acid generators converted to acid by the selected photolysis mechanism or ionization mechanism; calculating resist reactions between the acid generators and the quenchers in the photoresist volume which produces a model of the photoresist that indicates which portions of the photoresist has been exposed and to what degree; calculating a development of the photoresist volume which determines the effects of a developing solution upon the exposed portions of the photoresist; producing with the processor a three-dimensional simulated scanning electron microscope image of the photoresist profile created by the development of the photoresist volume; measuring the dimensional properties of the photoresist profile using a CDSEM simulator running on the processor; and specifying processes for fabricating integrated circuits based at least on the dimensional properties of the photoresist profile. inputting photoresist and exposure parameters into a stochastic model of a photoresist process with the steps and of determining a number of acid generators and quenchers within a photoresist volume; determining a refractive index and irradiance of the photoresist volume; computing the photoresist profile from the stochastic model using the processor with the steps (18, 20, 22, 24, 28, 30, 32) of determining a number of photons absorbed by the photoresist volume; determining which one of a photolysis mechanism or an ionization mechanism is most appropriate and selecting either the photolysis mechanism or the ionization mechanism; determining (22, 24) a number of the acid generators converted to acid by the selected photolysis mechanism or ionization mechanism; calculating resist reactions between the acid generators and the quenchers in the photoresist volume which produces a model of the photoresist that indicates which portions of the photoresist has been exposed and to what degree; calculating a development of the photoresist volume which determines the effects of a developing solution upon the exposed portions of the photoresist; producing with the processor a three-dimensional simulated scanning electron microscope image of the photoresist profile created by the development of the photoresist volume; measuring the dimensional properties of the photoresist profile using a CDSEM simulator running on the processor; and specifying processes for fabricating integrated circuits based at least on the dimensional properties of the photoresist profile.