Abstract:
A method for forming a field effect transistor device includes patterning an arrangement of fin portions on a substrate, patterning a gate stack portion over portions of the fin portions and the substrate, growing an epitaxial material from the fin portions that electrically connects portions of adjacent fin structures, and removing a portion of the gate stack portion to expose a portion of the substrate.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is a divisional of U.S. patent application Ser. No. 13/293,207 filed Nov. 10, 2011, now U.S. Pat. No. 8,697,514, the disclosure of which is incorporated by reference herein in its entirety. 
    
    
     BACKGROUND 
     The present invention relates to field effect transistor (FET) devices, and more specifically, to methods for fabrication and multi-gate FET devices. 
     Multi-gate FET devices include FinFET devices which are non-planar transistors disposed on a substrate. The FinFET device often includes active source and drain regions and a channel region that are formed from a silicon fin. The channel region is wrapped with gate materials such as polysilicon, metal materials, or high-k materials. 
     BRIEF SUMMARY 
     According to one embodiment of the present invention, a method for forming a field effect transistor device includes patterning an arrangement of fin portions on a substrate, patterning a gate stack portion over portions of the fin portions and the substrate, growing an epitaxial material from the fin portions that electrically connects portions of adjacent fin structures, and removing a portion of the gate stack portion to expose a portion of the substrate. 
     According to another embodiment of the present invention, a field effect transistor device includes an arrangement of fin portions disposed on a substrate, a first gate stack portion arranged over the arrangement of fin portions and portions of the substrate, a first epitaxial material connecting portions of the fin portions arranged in a first region defined by a first side of the first gate stack portion, a second epitaxial material connecting portions of the fin portions arranged in a second region defined by a second side of the first gate stack portion, and a second gate stack portion arranged substantially collinear to the first gate stack portion, the first gate stack portion and the second gate stack portion partially defined by a region of the substrate arranged between the first gate stack portion and the second gate stack portion. 
     Additional features and advantages are realized through the techniques of the present invention. Other embodiments and aspects of the invention are described in detail herein and are considered a part of the claimed invention. For a better understanding of the invention with the advantages and the features, refer to the description and to the drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
       The subject matter which is regarded as the invention is particularly pointed out and distinctly claimed in the claims at the conclusion of the specification. The forgoing and other features, and advantages of the invention are apparent from the following detailed description taken in conjunction with the accompanying drawings in which: 
         FIG. 1  illustrates a perspective view of an exemplary arrangement of FinFET devices. 
         FIGS. 2-14  illustrate an exemplary method of fabrication and resultant embodiment of FinFET devices. In this regard: 
         FIG. 2  illustrates a top view of fin portions arranged on a substrate. 
         FIG. 3  illustrates the resultant structure following the removal of a fin portion. 
         FIG. 4  illustrates the resultant structure following the formation of gate stack portions. 
         FIG. 5  illustrates the resultant structure following the formation of spacers over and adjacent to the gate stack portions. 
         FIG. 6  illustrates the resultant structure following the epitaxial growth of an epitaxial material. 
         FIG. 7  illustrates a side cut-away view along the line  7  of  FIG. 6 . 
         FIG. 8  illustrates an example of a photolithographic mask material. 
         FIG. 9  illustrates a side cut-away view along the line  9  of  FIG. 8 . 
         FIG. 10  illustrates the resultant structure following an etching process that removes the exposed portion of the oxide layer. 
         FIG. 11  illustrates the resultant structure following an etching process that removes exposed portions of the spacer. 
         FIG. 12  illustrates the resultant structure following an etching process that removes exposed portions of the gate stack. 
         FIG. 13  illustrates the resultant structure following the removal of the masking layer of  FIG. 12 . 
         FIG. 14  illustrates a top view of the resultant FinFET structure illustrated in  FIG. 13 . 
     
    
    
     DETAILED DESCRIPTION 
     Previous fabrication methods for FinFET devices included forming epitaxial regions that connect portions of adjacent fins of the FinFET devices following the patterning and fabrication of gate stacks. These methods may result in the formation of epitaxial regions that undesirably cause an electrical short between fins on opposing sides of the gate stack due to the geometry of the gate stack and the spacing of the adjacent fins. 
       FIG. 1  illustrates a perspective view of an exemplary arrangement of FinFET devices  102 . The FinFET devices  102  include fin portions that are arranged in parallel on an insulator layer  101  of a substrate  100 . A gate stack portion  106  is disposed over portions of the fin portions. A portion of the gate stack portion  106  has been removed such that a region  103  of the substrate  100  is exposed. In some embodiments, an epitaxial growth process may be performed to grow epitaxial material (not shown) from the exposed portions of the fin portions. It is desirable to grow the epitaxial material such that the exposed portions of the fin portions  104   a  are connected to each other on one side of the gate stack portion  106 , while the exposed portions of the fin portions  104   b  are connected to each other on the opposing side of the gate stack portion  106 . The fin portions  104  are arranged such that the spaces between the fin portions may be filled with the epitaxial material; however, it is undesirable to grow epitaxial material in the region  103  since the epitaxial material may form an electrical short between the fin portions  104   a  and  104   b . The end of the gate stack portion  106  that defines a distance (x) from the end of the gate stack portion  106  to the adjacent fin portions  104   a  and  104   b  may sufficient to prevent undesired epitaxial growth in the  103  region, however if the distance x is less than the distance (y) defined by adjacent fin portions, the epitaxial growth in the region  103  may cause a short between the fin portions  104   a  and  104   b . Thus, a method for fabricating a structure that allows epitaxial growth to connect adjacent fin portions without connecting opposing fin portions is described below. 
       FIG. 2  illustrates a top view of fin portions  202  arranged on a substrate  201 . The substrate  201  may include, for example, an insulator layer. The fin portions  202  may be formed by any suitable process such as, for example, a lithographic patterning and etching process, and may include a silicon or germanium material. The fin portions  202  are arranged substantially parallel to each other, and define a distance (a) between each fin portion  202 . 
       FIG. 3  illustrates the resultant structure following the removal of a fin portion  202  using, for example, a lithographic patterning and etching process. Though the illustrated embodiment shows the removal of one fin portion  202 , any number of fin portions  202  may be removed according to design specifications. 
       FIG. 4  illustrates the resultant structure following the formation of gate stack portions  402   a ,  402   b . The gate stack portions  402   a ,  402   b  may be formed by any suitable deposition, patterning and etching process. For example, a gate dielectric material (not shown) such as an oxide or high-k material may be disposed over the substrate  201  and the fin portions  202 , and a gate electrode material such as a polysilicon material may be formed over the gate dielectric material. A lithographic patterning and etching process may be used to form the gate stack portions  402   a ,  402   b . The fin portions  202  are arranged substantially parallel to each other, and the gate stack portions  402   a ,  402   b  are arranged substantially perpendicular to the fin portions  202 . 
       FIG. 5  illustrates the resultant structure following the formation of spacers  502  over and adjacent to the gate stack portions  402   a ,  402   b  (of  FIG. 4 ). The spacers  502  may include, for example, an oxide or nitride material. 
       FIG. 6  illustrates the resultant structure following the epitaxial growth of an epitaxial material  602  that may include, for example, a silicon or germanium material. In this regard, the epitaxial material  602  is grown from exposed portions of the fin portions  202  such that some of the adjacent fin portions  202  are connected. An oxide material  604  may be formed on surfaces of the fin portions  202  and the spacers  502  (or in some embodiments the gate stack portions  402   a ,  402   b ) to prevent epitaxial growth from undesired portions of the devices. The epitaxial material  602  is grown from the sidewalls of the fin portions  202 . The epitaxial growth process is timed or metered such that the epitaxial material  602  grown from adjacent fin portions  202  contact each other. In this regard, the epitaxial growth process is performed such that the epitaxial material  602  grows approximately ½ a from opposing sides of the fin portions  202 . The epitaxial material  602  grown in the region  601  for example, extends from the fin portion  202   a  and  202   b , however, the gate stack portion  402   b  inhibits epitaxial growth of the epitaxial material  602  that would result in an electrical short or connection between the fin portions  202   a  and  202   b  via epitaxial material  602 . 
       FIG. 7  illustrates a side cut-away view along the line  7  (of  FIG. 6 ) and shows epitaxial material  602  arranged on the substrate  201 . 
       FIG. 8  illustrates an example of a photolithographic mask material  801  that has been patterned on exposed portions of the substrate  201 , the fin portions  202 , the epitaxial material  602 , and portions of the gate stacks  402  (and/or portions of materials such as the spacers  502  and oxide layer  604  that may be formed over the gates stacks  402 ). A portion of the gate stack  402   a  remains exposed. 
       FIG. 9  illustrates a side cut-away view along the line  9  (of  FIG. 8 ). 
       FIG. 10  illustrates the resultant structure following an etching process that removes the exposed portion of the oxide layer  604 . The etching process may include any suitable etching process such as, for example, a dry etching process or reactive ion etching (RIE). 
       FIG. 11  illustrates the resultant structure following an etching process that removes exposed portions of the spacer  502  to expose a portion of the gate stack  402   a , such as, for example a dry etching process. 
       FIG. 12  illustrates the resultant structure following an etching process that removes exposed portions of the gate stack  402   a . In this regard, the etching process may include a dry etch or RIE process that is selective to the spacer material (e.g., SiN) and oxide materials. 
       FIG. 13  illustrates the resultant structure following the removal of the masking layer  801  (of  FIG. 12 ), the deposition of an oxide material  1302  over exposed portions of the substrate  201 , and a chemical mechanical process (CMP) or other suitable planarizing process. 
       FIG. 14  illustrates a top view of the resultant FinFET structure illustrated in  FIG. 13 . The region  1401  illustrates the portion of the gate stack  402   a  (of  FIG. 4 ) and the spacers  502  that were removed following the growth of the epitaxial material  602  as described above. The gate stack  402   a  and the spacers  502  inhibited the growth of epitaxial material  602  in the region  1401  thereby reducing the likelihood that the fin portions  1402   a  and  1402   b  could be electrically connected or shorted by the epitaxial material  602 . The removal of the portion of the gate stack  402   a  in the region  1401  results in gate stack portions  402   a  and  402   c  arranged collinear along the line  1420  that illustrates longitudinal axis of the gate stack portions  402   a  and  402   c , where the gate stack portions  402   a  and  402   c  are partially defined by the region  1401 . 
     The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises” and/or “comprising,” when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one more other features, integers, steps, operations, element components, and/or groups thereof. 
     The corresponding structures, materials, acts, and equivalents of all means or step plus function elements in the claims below are intended to include any structure, material, or act for performing the function in combination with other claimed elements as specifically claimed. The description of the present invention has been presented for purposes of illustration and description, but is not intended to be exhaustive or limited to the invention in the form disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the invention. The embodiment was chosen and described in order to best explain the principles of the invention and the practical application, and to enable others of ordinary skill in the art to understand the invention for various embodiments with various modifications as are suited to the particular use contemplated 
     The diagrams depicted herein are just one example. There may be many variations to this diagram or the steps (or operations) described therein without departing from the spirit of the invention. For instance, the steps may be performed in a differing order or steps may be added, deleted or modified. All of these variations are considered a part of the claimed invention. 
     While the preferred embodiment to the invention had been described, it will be understood that those skilled in the art, both now and in the future, may make various improvements and enhancements which fall within the scope of the claims which follow. These claims should be construed to maintain the proper protection for the invention first described.