Browse Prior Art Database

Electrostatic Cleaner for Integrated Circuit Devices

IP.com Disclosure Number: IPCOM000083676D
Original Publication Date: 1975-Jul-01
Included in the Prior Art Database: 2005-Mar-01
Document File: 3 page(s) / 39K

Publishing Venue

IBM

Related People

Li, LB: AUTHOR [+2]

Abstract

This electrostatic cleaner is useful for cleaning integrated circuit (IC) devices and the like, and it can be used one or more times during one or more different processing steps or stages associated with the fabrication of IC devices. For example, it can be used at least once during the .wafer preparation stage of an IC fabrication process.

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Electrostatic Cleaner for Integrated Circuit Devices

This electrostatic cleaner is useful for cleaning integrated circuit (IC) devices and the like, and it can be used one or more times during one or more different processing steps or stages associated with the fabrication of IC devices. For example, it can be used at least once during the .wafer preparation stage of an IC fabrication process.

More specifically, after the semiconductor substrate has been prepared as a finished wafer and prior to the wafer being subsequently subjected to the diffusion processing steps in the case of a planar diffused fabrication process or, alternatively, prior to the wafer being subsequently subjected to the epitaxial layer deposition processing steps in the case of an epitaxial IC fabrication process, the wafer surface at which these subsequent processing steps are to be effected is cleaned by this apparatus.

As such, wafers W in the figure are finished substrates of semiconductor material, e.g., silicon, which are appropriately doped and have a polished surface S at which the aforementioned diffusion or epitaxial processing steps will be subsequently affected. Located on surfaces S are particulates, not shown, which are to be removed prior to the operation of the aforementioned subsequent processing steps. The particulates may be small particles of the semiconductor material used in the substrate, or may be some other foreign particles formed from the other materials used in the associated processes or from any other materials, such as airborne matter in the form of dust and dirt and the like.

A grounded conveyor belt B, which is part of a transport system, not shown, carries each wafer W to an electrostatic charging station 1 in the direction of arrow A. Station 1 electrostatically charges the wafer W and provides the wafer surface S with an electrostatic polarity opposite to that which it provides in the remainder R of the wafer W. The particulates, as a result, are induced with the same electrostatic polarity as that of the surface S, but opposite to that in the wafer's remainder R.

For this purpose, charging station 1 has an ionizer 2 which ionizes the medium, e.g., air, adjacent the surface S, and thus provides the wafer W with an electrostatic negative polarity charge type bombardment. A secondary emission collector 3, which is disposed in proximity to the ionizer 2, collects the secondary electrons released from the surface S due to the ion bombardment thereof by the ionized gas medium. This causes an opposite electrostatic charge polarity, to wit: positive, to be effected on surface S. As a result, the surface S of wafer W and, hence, the particulates to be removed are of the same polarity type and the remainder R of wafer W is of the opposite polarity type.

Ionizer 2 includes a corona wire 21 having one end connected to the negative terminal 22 of an adjustable and controlled high-voltage source 23, e.g., 10 kv to 14 kv. The positive te...