Fairchild Camera and Instrument Corp.

Robert L Berry

Jay A Shideler

Wen-Chuang Ko

Steven J Radigan

A method of defining narrow regions in an underlying integrated circuit structure includes the steps of depositing a first layer of material 30 having selected etching characteristics on the underlying integrated circuit structure, depositing a second layer of material 32 having etching characteristics different from the first layer 30 on the first layer 30, anisotropically etching the first layer 30 and the second layer 32 from all of the underlying integrated circuit structure 26 except for a desired region having a periphery which includes the narrow region, forming a coating 35 of smoothing material over all of the underlying integrated circuit structure 26 except for the first layer 30, and isotropically etching the first layer 30 to remove it from the surface of the underlying integrated circuit structure 26 to thereby define the narrow region 36. Use of the process to fabricate a compact bipolar transistor structure is also disclosed.

Method of fabricating integrated circuit structures using replica

A lateral bipolar transistor having a base width of 0.5 micron or less is made by forming a protective layer on an electrically insulating layer along a surface of a semiconductor body, forming an open space through the protective layer so as to define a guiding edge for it, introducing a first semiconductor dopant of a selected conductivity type into the body using the guiding edge to control the lateral extent of the first dopant, etching the insulating layer back under the protective layer a selected distance from the guiding edge, oxidizing material of the body exposed by the open space in the protective and insulating layers to form a composite electrically insulating region, removing the remainder of the protective layer, etching the insulating region sufficiently long to create an open space through it and thereby define another guiding edge, and introducing a second semiconductor dopant of the selected conductivity type into the body using this second guiding edge to control the lateral extent of the second dopant toward the first dopant and thereby to control the resulting base width.

Method of forming self-aligned lateral bipolar transistor

A semiconductor structure is fabricated using a process involving all ion implantation and using only five masks prior to metallization. A buried contact mask is used to form a buried contact layer (114), an isolation mask is used to form grooves (130a, 130b) in an epitaxial layer of silicon (113), a self-aligned transistor mask is used to form a mask (134a to 134e) to define the areas in which emitters (138a, 140b, 140c) bases (113, 139) and contact regions (140a) are to be formed, a base exclusion mask (135a,b) is provided to exclude certain impurities from being implanted into a region to be formed of one conductivity type, and a second exclusion mask (137a, 137b) is provided to exclude impurities to be implanted in a region of opposite conductivity type from the prohibited regions of the structure. The last ion implantation of the device is a two-level implantation to yield a shallow implant which provides good ohmic contact to certain to-be-formed metal contact areas and a deep implant to provide current gain control for the base of the NPN transistors (Q.sub.1, Q.sub.2). The metal contacts to active regions on the device are formed merely by etching the device to remove a thin oxide (131) over these regions. A thicker oxide (134a through 134e) overlying all other regions of the device is substantially unaffected by this etching.

Method for the formation of high density memory cells using ion

A process for patterning plasma etchable regions on a semiconductor structure includes the steps of forming a layer of an oxide of aluminum over the surface of the semiconductor structure, forming an overlying layer of plasma etchable material on the layer of oxide, and removing undesired portions of the overlying layer by plasma etching to thereby expose portions of the layer of oxide. In some embodiments of the invention the thereby exposed portions of the layer of oxide are then removed, together with any underlying portions of the first layer, by isotropic etching.

Process for patterning metal connections on a semiconductor structure by

In an oxide isolated semiconductor structure having an epitaxial layer formed on a monocrystalline substrate, a buried, laterally extending PN isolation junction in said structure, and oxidized isolation regions extending through said epitaxial layer to said PN isolation junction, thereby to form a plurality of electrically isolated pockets of semiconductor material, a dopant is located in those regions of the semiconductor material directly adjacent the oxidized isolation regions to prevent unwanted current flow called 'channeling.' The region formed by this dopant is often referred to as the field predeposition region. Typically, to form the field predeposition region, a selected dopant is placed in the exposed surface regions of the epitaxial semiconductor material just prior to the formation of the oxidized isolation regions. The field predeposition and oxidation of the epitaxial semiconductor material also cause the formation of a conductive buried region from that portion of the field predeposition dopant in the epitaxial pockets directly adjacent the oxidized semiconductor material. If desired, a collector sink then may be formed in the epitaxial pocket without disrupting the function of the conductive buried region. The conductive buried region may be utilized to facilitate manufacture of smaller memory circuits than heretofore available, compact junction field effect transistors, and other integrated circuit structures.

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Cupertino, CA, United States of America

Robert L Berry