USA As Represented by Secretary of the Navy

David J Godbey

Francis J Kub

Syed B Qadri

Harold L Hughes

A method of producing a silicon membrane has a step of forming an etch stop layer on an upper surface of a silicon substrate having lower and upper opposing surfaces, the etch stop layer comprising an alloy of silicon and at least one other Group IV element. The method of producing a silicon membrane has another step of forming a cap layer on the etch stop layer, the cap layer having lower and upper opposing surfaces with the lower surface contacting the etch stop layer. The method of producing a silicon membrane has a further step of removing a portion of the silicon substrate at a time when the upper surface of the cap layer is exposed, the portion of the silicon substrate being removed extending from the upper surface of the silicon substrate to the lower surface of the silicon substrate to thereby define an exposed portion of the etch stop layer. The exposed portion of the etch stop layer may be removed. Also, the formed membrane can be further processed to define undoped device structures isolated by thin silicon legs. According to another embodiment, a cap layer is never formed and the etch stop layer itself functions as the membrane.

Method of producing a silicon membrane using a silicon alloy etch stop

A monocrystalline germanium film is grown on a sapphire substrate with a (1102) orientation. The substrate is first pretreated to restructure the (1102) surface plane. Typically, restructuring is accomplished by either an anneal at high temperature or ion bombardment. A monocrystalline germanium layer is grown on the pretreated surface by a vapor deposition process such as molecular beam epitaxy or chemical vapor deposition.

Monocrystalline germanium film on sapphire

A process for fabricating thin film silicon wafers using a novel etch stop composed of a silicon-germanium alloy includes properly doping a prime silicon wafer for the desired application, growing a strained Si.sub.1-x Fe.sub.x alloy layer onto seed wafer to serve as an etch stop, growing a silicon layer on the strained alloy layer with a desired thickness to form the active device region, oxidizing the prime wafer and a test wafer, bonding the oxide surfaces of the test and prime wafers, machining the backside of the prime wafer and selectively etching the same to remove the silicon, removing the strained alloy layer by a non-selective etch, thereby leaving the device region silicon layer. In an alternate embodiment, the process includes implanting germanium, tin or lead ions to form the strained etch stop layer.

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Bethesda, MD, United States of America

David J Godbey