Patent FR-2788708-A1 (FR)
Title: Apparatus and method for treatment of surfaces of semiconductor substrates, comprising cylindrical chamber with bath, injectors for liquid, vibrators, positioning and emptying devices
Inventor: GIRARDIE LIONEL
IPC: B08B3/10
Filed: 1999-01-26
Abstract: The apparatus comprises a cylindrical chamber (2) with counter-chamber (3), a system of injectors for the distribution of liquid, a system of vibrators (13) in the interior walls (12) of the chamber (2), a system for input, output and holding of wafers (9) in the chamber, and emptying device (11). The counter-chamber (3) comprises an upper level (4) separated from a lower level (6) by a partition (5) in the form of plate with openings.  The upper level (4) is a collector for doped rinsing and drying solutions utilized in the treatment of wafers. The lower level (6) is used as a reservoir for the recovery of liquid after passage through the chamber (2). The injection system allows two different and complementary methods of liquid input, distribution by gravity action from three pipes with openings mounted in length of cylinder, and lateral injection by utilizing six pipes with openings and jet parallel to the wafers as controlled in direction by an input of nitrogen. The vibration device (13) mounted on the interior walls of chamber is for the generation of acoustic waves which propagate perpendicular to the walls of chamber and traverse the bath towards the interior of chamber (2). The vibration device (13) comprises eight (8) piezoelectric zones in the form of transducers located around the chamber (2) and functioning in the frequency range from 500 kHz to 5 MHz. The acousting waves sweep the wafers in vertical plane on front and rear surfaces. The acoustic waves are generated in synchronous mode by the propagation of waves of the same frequency from two opposite piezoelectric zones, or in asynchronous mode by the propagation of acoustic waves of different frequencies from two consecutive piezoelectric zones. The emptying device (11) consists of a valve with diaphragm for isolating the chamber, and after the treatment of wafers emptying the chamber by gravity action. The holding system comprises a structure of stainless steel bars of predetermined diameter fastened at the bottom of chamber, and a structure of paired hollow tubes made of polymeric material which fit the bars structure; the hollow tubes structure supports the wafers, which can slide on the bars structure to the center of chamber (2). The doped rinsing solution can be a combination of two or three solutions, which is obtained by the dissolution of a gas in ultra pure water by bubble injection; the gas is hydrogen chloride (HCI), ozone (O3), or hydrogen fluoride (HF). The apparatus also comprises principal and support heat-exchangers for maintaining the temperature of liquid injection below 19 deg.C, valves and a set of filters of type: chemical, membrane for the capture of particles, positive membrane and negative membrane. The treatment of wafers (9) by rinsing solution is in stages before growth of layers as oxide or epitaxial, and includes the injection of the rinsing solutions after combining during predetermined time intervals. The injection of drying solution is close to the state of vaporization.