University of Delaware

Sourav K Sengupta

Henry C Foley

Robert D Varrin, Jr

A beam or flow of a reactive or metastable precursor such as a hydride or organometallic compound is created, and this beam or flow is used to treat (e.g. dope or coat or otherwise modify) a substrate, e.g. an advanced material such as a semiconductor layer, a photovoltaic cell, or a solar cell. The beam or flow can also be directed into a storage zone so that the precursor or precursors can be collected for future use. The beam or flow is created in an apparatus comprising at least three zones. Zone 1 is irradiated with microwave energy to generate a reactive gas rich in free radicals (e.g. rich in H.sup.., CH.sub.3.sup.., etc.) zone 2 (downstream from zone 1) is substantially free of microwave energy and contains a target which is impinged upon by the free radicals and becomes a source of the precursor; zone 3 (downstream from zone 2) is where the precursors are either collected for storage or are used to treat the substrate. In a typical apparatus of this invention, a feed gas such as H.sub.2 or CH.sub.4 is introduced into an elongated tube 50 which communicates with a microwave cavity 57 containing a microwave plasma. A reactive gas containing free radicals (and perhaps some ions) flows from cavity (57 to target 61, where the free radicals react with the target to form the precursor (e.g. a hydride such as silane). When the precursor enters zone 3 it can treat an advanced material 73, e.g. by decomposing into Si+2H.sub.2. The Si is deposited on substrate 73 and the liberated H.sub.2 is pumped away. The pumping system also keeps the interior of the apparatus under subatmospheric pressure, e.g. 0.1 to 10 torr.

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Newark, DE, United States of America

Sourav K Sengupta