Browse Prior Art Database

Float Processing

IP.com Disclosure Number: IPCOM000079442D
Original Publication Date: 1973-Jul-01
Included in the Prior Art Database: 2005-Feb-26
Document File: 2 page(s) / 45K

Publishing Venue

IBM

Related People

Bohan, LM: AUTHOR [+2]

Abstract

In float processing of semiconductor wafers, that is, etching the wafer for subsequent deposition of metals, impurities etc., stagnation of the liquid may occur directly beneath the wafer as it floats on the liquid. Additionally, it may be desirable to effect a greater etching of the wafer at certain localized portions thereof than at other portions. To accomplish a uniform processing of the wafer, the embodiments of Figs. 2 and 3 may be employed wherein, for example, a porous convexly shaped disk 10 (Fig. 3) is connected to the walls 11 of a processing tank in which liquid is forced through the disk, and impinges upon the underside of a wafer, the process liquid being removed as through sidewall conduits 12.

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Float Processing

In float processing of semiconductor wafers, that is, etching the wafer for subsequent deposition of metals, impurities etc., stagnation of the liquid may occur directly beneath the wafer as it floats on the liquid. Additionally, it may be desirable to effect a greater etching of the wafer at certain localized portions thereof than at other portions. To accomplish a uniform processing of the wafer, the embodiments of Figs. 2 and 3 may be employed wherein, for example, a porous convexly shaped disk 10 (Fig. 3) is connected to the walls 11 of a processing tank in which liquid is forced through the disk, and impinges upon the underside of a wafer, the process liquid being removed as through sidewall conduits 12.

In the embodiment in Fig. 2 the insert 15, also porous, is made with a substantially plain upper surface 15a, while the lower surface 15b is cone shaped. This structure permits a higher velocity liquid discharge onto the underside of the wafer near the central portion and a lower velocity discharge near or adjacent its periphery. Once again the insert 15 is connected to the walls of the tank 16 and liquid discharge is effected through the sidewall conduits 17.

In the embodiment illustrated in Fig. 1, differential velocities may be achieved in a uniform density insert 20 so as to effect greater etching on selected portions of a wafer 21, by providing, at selected locations, cut outs 22 in the insert. Once again the insert may be connected in...