US 5,711,812 AGranted

Apparatus for obtaining dose uniformity in plasma doping (PLAD) ion implantation processes

AssigneeVarian Associates, Inc.

InventorsDavid LeRoy Chapek, Susan Benjamin Felch, Michael William Kissick, Shamim Muhammad Malik, Tienyu Terry Sheng

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Abstract

An apparatus for improving dose uniformity in the PLAsma Doping (PLAD) ion implantation of a target material is described. By providing means for simultaneously biasing both the electrode, upon which the target is disposed, and a separately biasable concentric structure introduced about the electrode and sufficiently close to the target, together with means for adjustable bias variation between the electrode and the structure one can sufficiently adjust the shape of the implantation plasma, e.g. induced electric field and plasma sheath thickness, in order to effectively provide a uniform dose distribution during PLAD ion implantation processes.

Claims8

Dependent claims

Apparatus for accomplishing PLAsma Doping (PLAD) ion implantation comprising:

an electrode enclosed in a vacuum chamber;
a target disposed upon said electrode;
means for maintaining a plasma having dopant ions at an implantation surface of said target;
a concentric structure of suitably conductive material being electrically isolated from said target bearing electrode and disposed so as to surround said electrode while being sufficiently close to said target;
and
means for separately biasing said electrode concurrently with said concentric structure in order to provide adjustable bias variation between said electrode and said structure capable of providing dose uniformity during said PLAD ion implantation of said target.

3 more elements

Dependencies are inferred from the claim text.