REMOVAL OF SMALL PARTICLES-DEPOSITED ON S OLID-SURFACES BY A FREEZINGMETHOD

A new method of particle removal from solid surfaces, which will be ca lled the ''freezing and melting method'', has been proposed. Substrate s or materials to be cleaned are dipped into a certain liquid (ultrapu re water with surfactant or methanol), and the liquid is frozen by liq uid nitrogen and then melted. Submicron particles deposited on substra tes (Si wafer and slide glass) were found to be effectively removed by this simple procedure. The main mechanisms of the particle removal ar e thought to be an expelling effect at the front of freezing (a kind o f coacervation) and the difference in thermal shrinkage between frozen liquid and subtsrate.