Abstract:
A method of automated generation of oxide pillar (PX) slot shapes of a PX layer within silicon-on-insulator (SOI) structures that includes generating a placement grid on recess oxide (RX) shapes, creating PX placement markers on the placement grid along a perimeter of the RX shapes, filtering the PX placement markers, generating a PX slot shape corresponding to each filtered PX placement marker on the RX shapes, correcting location errors associated with the generated PX slot shapes, generating PX slot shapes on RX shapes of a predetermined size for which PX slot shapes were not generated, performing a verification operation of the PX slot shapes, and outputting the PX layer including the verified PX slot shapes.

Description:
BACKGROUND 
     The present invention relates to the generation of oxide pillar (PX) slot shapes in localized silicon-on-insulator (SOI) formation technology, and more specifically, to the automatic and orderly placement of rectangular PX slot shapes in complex sets of structures associated with localized SOI formation technology. 
     Today, in SOI formation technology, rectangular shapes (i.e., PX slot shapes) are placed on the edges of recess oxide (RX) shapes to allow for etching of slots and subsequent undercutting of epitaxial (epi) regions which form localized SOI regions.  FIG. 1  illustrates a PX layer of an SOI structure according to the conventional art. As shown in  FIG. 1 , bulk silicon substrate  10  is provided where an epi region  12  is formed on top of the bulk silicon substrate  10  and a pad nitride film  14  is formed above the epi region  12 . A PX layer  16  including a PX slot shape  11  is formed on top of a pad nitride film  14  and a PX opening  18  and a lateral trench  20  formed by reactive ion etching (RIE) is also provided. 
     In a conventional method of forming PX slot shapes, the placement of the shapes is performed manually during manufacturing. Typically, as shown in  FIG. 2 , the PX slot shapes formed in L-shapes, T-shapes, and vertical or horizontal shapes positioned in parallel. However, there are several problems associated with the conventional method. As shown in  FIG. 2 , since the PX slot shapes are manually placed on the RX shapes, some of the PX slot shapes may not be formed properly. For example, as shown in  FIG. 2 , the circled portion  15  indicates PX slot shapes positioned perpendicular to one another which are too close to one another and the circled portion  20  indicates PX slot shapes formed offset and in parallel, which are too close to one another. 
     SUMMARY OF THE INVENTION 
     The present invention provides an automated solution for placement of rectangular PX slot shapes in complex sets of structures associated with localized SOI formation technology during a manufacturing phase, to minimize manufacturability problems. 
     According to one embodiment of the present invention, a method of automated generation of oxide pillar (PX) slot shapes of a PX layer within silicon-on-insulator (SOI) structures is provided. The method includes generating a placement grid on recess oxide (RX) shapes, creating PX placement markers on the placement grid along a perimeter of the RX shapes, filtering the PX placement markers, generating a PX slot shape corresponding to each filtered PX placement marker on the RX shapes, correcting location errors associated with the generated PX slot shapes, generating PX slot shapes on RX shapes of a predetermined size for which PX slot shapes were not generated, performing a verification operation of the PX slot shapes, and outputting the PX layer including the verified PX slot shapes. 
     According to another embodiment of the present invention, a computer program product performing the above-mentioned method is also provided. 
     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 an oxide pillar (PX) layer of an SOI structure according to the conventional art. 
         FIG. 2  illustrates an oxide pillar (PX) open level according to the conventional art. 
         FIG. 3  is a flow chart illustrating a method for generating a PX layer that can be implemented within embodiments of the present invention. 
         FIG. 4  is a diagram illustrating recess oxides (RX) shapes that can be implemented within embodiments of the present invention. 
         FIG. 5  is a diagram illustrating a placement grid generated according to embodiments of the present invention. 
         FIG. 6  is a diagram illustrating the generation of PX placement markers that can be implemented according to embodiments of the present invention. 
         FIG. 7  is a diagram illustrating the formation of PX slot shapes that can be implemented within embodiments of the present invention. 
         FIG. 8  is an exploded view of a portion of the diagram shown in  FIG. 7 . 
         FIG. 9  is an exploded view illustrating location corrections made to PX slot shapes according to an embodiment of the present invention. 
         FIG. 10  is a diagram illustrating a placement of a custom PX slot shape on a small RX shape that can be implemented within embodiments of the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     With reference now to  FIG. 3 , there is a flow chart illustrating a method for generating a PX layer according to embodiments of the present invention. The operations shown in  FIG. 3 , for generating a PX layer will be discussed below with reference to  FIGS. 4 through 10 . 
     As shown in  FIG. 4 , according to an embodiment, RX shapes  30  are formed on a bulk silicon substrate  32 . According to an embodiment of the present invention, a placement grid  50  (i.e., a marking grid) as depicted in  FIG. 5  is generated on top of RX shapes  30  (operation  100  of  FIG. 3 ). From operation  100 , the process moves to operation  110 , where PX placement markers  60   a  and  60   b  (depicted in  FIG. 6 ) are created wherever the placement grid  50  intersects any of the RX shapes  30 . That is, where the horizontal grid lines intersect the vertical edges (i.e., the left and right edges) of the RX shapes  30 , and where the vertical grid lines intersect the horizontal edges (i.e., the top and bottom edges) of the RX shapes  30 , PX placement markers  60   a  and  60   b  are created, respectively. 
     Once the PX placement markers  60   a  and  60   b  are created in operation  110 , the process moves operation  115 , where invalid PX placement markers  60   a  and  60   b  are filtered out by performing a check of the PX placement markers  60   a  and  60   b  using a set of predetermined PX placement marker rules. According to an embodiment of the present invention, the set of PX placement marker rules may include, for example, determining whether the PX placement markers  60   a  and  60   b  do not land on the perimeter edges of an RX shape  30 , determining whether a PX placement marker is too close to the corner of an RX shape  30 , determining whether a PX placement marker  60   a  and  60   b  is too close to an adjacent RX shape  30 , and determining whether a PX placement marker  60   a  and  60   b  is on an RX shape  30  which is less than a predetermined size, for example. As a result, all invalid PX placement markers  60   a  and  60   b  are deleted. According to one embodiment of the present invention, in some cases, the PX placement markers  60   a  and  60   b  may be recreated. For example, when a plurality of PX placement markers  60   a  and  60   b  are deleted from a respective RX shape  30 , one of the PX placement markers  60   a  and  60   b  may be recreated now that the other PX placement markers  60   a  and  60   b  are deleted from the respective RX shape  30 . 
     Once it is determined that the PX placement markers  60   a  and  60   b  are all valid in operation  115 , the process moves to operation  120 , where PX slot shapes  70  (as depicted in  FIG. 7 ) are generated corresponding to each PX placement marker  60   a  and  60   b . According to an embodiment of the present invention, the PX slot shapes  70  are generated on the placement grid  50  (as depicted in  FIG. 5 ). That is, according to an embodiment of the present invention, the PX slot shapes may only be placed on the vertical and horizontal lines of the grid  50 . The PX slot shapes  70  are generating using shapes generation tools, such as caliber software tools, to grow the PX placement markers  60   a  and  60   b  in a direction inside and outside of the respective RX shape  30 . 
     After the PX slot shapes  70  have been generated in operation  120 , the process moves to operation  125  where location corrections are made to errors regarding the PX slot shapes  70  corresponding to each PX placement marker  60   a  and  60   b . A set of predetermined ground rules are used to determine whether the PX slot shapes are satisfactory. The set of predetermined ground rules may include, for example, whether the PX slot shape  70  is of a minimum width or length, whether the PX slot shape  70  is of a predetermined area for a non-rectangular RX shape  30 , whether the PX slot shape  70  overlaps the respective RX shape  30  and whether it extends outside of the RX shape  30 . Examples of problems that may exist with PX slot shapes  70  can be seen in  FIG. 8 , for example. As shown in  FIG. 8 , there may be areas along the RX shape  30  where at least two PX slot shapes  70  are too close to each other as indicated by arrows  80  and  81 , for example. If so, according to an embodiment of the present invention, the respective PX slot shapes  70  may be merged together using the shapes generation tools to shrink or grow the PX slot shapes  70  in order to fix errors, as shown in  FIG. 9 . 
     According to an embodiment of the present invention, each RX shape  30  is required to have a PX slot shape  70  generated thereon. Therefore, when PX slot shapes  70  are not formed on small RX shapes  30   a  which are less than a predetermined size (as depicted in  FIG. 9 ), in operation  130  of  FIG. 3 , a custom PX slot shape  70   a  is generated on any small RX shapes  30   a  which did not have PX slot shapes  70  generated thereon, as shown in  FIG. 10 . According to an embodiment of the present invention, predetermined criteria may be used to generate custom PX slot shapes  70   a  on the small RX shapes  30   a , for example, if the RX shape  30   a  is wider in the x-direction (i.e., the horizontal) than in the y-direction then a custom PX slot shape  70   a  is generated vertically. On the other hand, if the RX shape  30   a  is wider in the y-direction (i.e., the vertical direction) than in the x-direction, then the custom PX slot shape  70   a  is generated horizontally. Further, the custom PX slot shape  70   a  may be of a size corresponding to the size of the respective small RX shape  30   a . The custom PX slot shape  70   a  is then checked using the predetermined ground rules to determine whether the custom PX slot shape  70   a  crosses the RX shape  30   a  and overlaps the RX shape  30   a  by a predetermined amount and to determine whether to custom PX slot shape  70   a  interferes with any of the existing PX slot shapes  70 . According to an embodiment of the present invention, the custom PX slot shapes  70   a  may not be formed on along the grid  50  shown in  FIG. 5 . 
     From operation  130 , the process moves to operation  135 , where PX slot shapes are generated on memory arrays according to an embodiment of the present invention. In one embodiment, PX slot shapes are custom generated on the RX shapes of each SRAM 
     From operation  135 , the process moves to operation  140 , where a final verification operation is performed. During the final verification operation, the PX slot shapes  70   a,    70   b  are examined using the set of predetermined ground rules as used in operation  125  so that any errors found may be corrected. Once the final verification operation has been performed, the process moves to operation  145  where a final PX layer including the verified PX slot shapes is outputted. 
     The method for generating PX slot shapes according to embodiments of the present invention involves the use of a placement grid when generating PX slot shapes, and performing error check and correction operations, which provides the advantage of performing automatic and orderly placement of PX slot shapes in complex sets of structures associated with localized SOI formation technology during the manufacturing phase, to thereby improve manufacturability. 
     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 ore 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 flow 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.