Abstract:
An integrated circuit comprises a first drain region having a symmetric shape across at least one of horizontal and vertical centerlines. A first gate region has a first shape that surrounds the first drain region. A second drain region has the symmetric shape. A second gate region has the first shape that surrounds the second drain region. A connecting gate region connects the first and second gate regions. A first source region is arranged adjacent to and on one side of the first gate region, the second gate region and the connecting gate region. A second source region is arranged adjacent to and on one side of side of the first gate region, the second gate region and the connecting gate region.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a Continuation of U.S. patent application Ser. No. 11/524,113 filed Sep. 20, 2006, which application claims the benefit of U.S. Provisional Application Nos. 60/825,517, filed Sep. 13, 2006, 60/824,357, filed Sep. 1, 2006, 60/823,332, filed on Aug. 23, 2006, 60/821,008, filed Aug. 1, 2006 and 60/798,568, filed on May 8, 2006 and is a continuation-in-part of U.S. patent application Ser. No. 11/252,010 filed on Oct. 17, 2005, which is a continuation of U.S. patent application Ser. No. 10/691,237 filed on Oct. 22, 2003. The disclosure of the above application is incorporated herein by reference in its entirety. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates to transistor structures, and more particularly to transistor structures with reduced chip area. 
     BACKGROUND OF THE INVENTION 
     Integrated circuits or chips may include a large number of interconnected transistors. The transistors and other circuit elements are interconnected in various ways to provide desired circuit functions. It is usually most efficient to fabricate multiple integrated circuits on a single wafer. After processing, the integrated circuits that are fabricated on the wafer are separated and then packaged. The wafer can accommodate a fixed number of integrated circuits for a given integrated circuit size. Reducing the size of individual transistors in the integrated circuit may help to reduce the overall size of the integrated circuit. This, in turn, allows an increased number of integrated circuits or chips to be made on each wafer and reduces the cost of the integrated circuits. 
     Referring now to  FIGS. 1 and 2 , an exemplary transistor  10  includes a drain  12 , a gate  14 , a source  16  and a body  18  or substrate tap. For example, the transistor  10  in  FIG. 1  is an NMOS transistor. In some circumstances, the body  18  is connected to the source  16  as shown in  FIG. 2 . 
     Referring now to  FIG. 3 , the body  18  includes a p +  region and may include a contact tap  30 . The source  16  includes an n +  region and may include a contact tap  32 . The drain  12  includes an n +  region and may include a contact tap  34 . Additional transistors may be fabricated on one or sides of the transistor  10  as indicated by “ . . . ” in  FIG. 3 . 
     Referring now to  FIG. 4 , the body  18  may be repeated between sources  16  of adjacent transistors. The body  18  takes up valuable chip area and increases the size of the transistor and the integrated circuit. Additional transistors can be arranged on one or more sides of the transistor  10  as shown by “ . . . ” in  FIG. 4 . 
     SUMMARY OF THE INVENTION 
     An integrated circuit comprises a first source, a first drain, a second source, a first gate arranged between the first source and the first drain, and a second gate arranged between the first drain and the second source. The first and second gates define alternating first and second regions in the drain. The first and second gates are arranged farther apart in the first regions than in the second regions. 
     In other features, a well substrate contact is arranged in the first regions. Alternatively, R well substrate contacts are arranged in the first regions, where R is an integer greater than one. R is an integer that is greater than three and less than seven. The integrated circuit includes a plurality of transistors. The transistors include PMOS transistors. The R well substrate contacts are associated with respective ones of R transistors. 
     In other features, the integrated circuit comprises a second drain; and a third gate arranged between the second source and the second drain. The second and third gates define alternating third and fourth regions. The second and third gates are arranged farther apart in the third regions than in the fourth regions. 
     In yet other features, the first regions are arranged adjacent to the fourth regions and the second regions are arranged adjacent to the third regions. The first and third regions include R well substrate contacts. 
     A method for providing an integrated circuit comprises providing a first source; providing a first drain; providing a second source; locating a first gate between the first source and the first drain; locating a second gate between the first drain and the second source; defining alternating first and second regions in the drain using the first and second gates; and arranging the first and second gates farther apart in the first regions as compared to the second regions. 
     In other features, the method includes locating a well substrate contact in the first regions. The method includes locating R well substrate contacts in the first regions, where R is an integer greater than one. R is an integer that is greater than three and less than seven. The integrated circuit includes a plurality of transistors. The transistors include PMOS transistors. The method includes associating the R well substrate contacts with respective ones of R transistors. 
     In other features, the method includes providing a second drain; providing a third gate between the second source and the second drain; defining alternating third and fourth regions using the second and third gates; and arranging the second and third gates are arranged farther apart in the third regions than in the fourth regions. 
     In other features, the method includes arranging the first regions adjacent to the fourth regions and the second regions adjacent to the third regions. The first and third regions include R well substrate contacts, where R is an integer greater than one. 
     An integrated circuit comprises a first drain region having a generally rectangular shape. First, second, third and fourth source regions have a generally rectangular shape and are arranged adjacent to sides of the first drain region. A gate region is arranged between the first, second, third and fourth source regions and the first drain region. First, second, third and fourth substrate contact regions are arranged adjacent to corners of the first drain region. 
     In other features, the first, second, third and fourth source regions have a length that is substantially equal to a length of the drain region. The first, second, third and fourth source regions have a width that is less than a width of the first drain region. The width of the first, second, third and fourth source regions is approximately one-half the width of the first drain region. 
     In other features, a second drain region has a generally rectangular shape and has one side that is arranged adjacent to the first source region. Fifth, sixth and seventh source regions have a generally rectangular shape. The fifth, sixth and seventh source regions are arranged adjacent to other sides of the second drain region. 
     In other features, a gate region is arranged between the first, fifth, sixth and seventh source regions and the second drain region. Fifth and sixth substrate contact regions are arranged adjacent to corners of the second drain region. The integrated circuit includes laterally-diffused MOSFET transistors. 
     A method for providing an integrated circuit comprises providing a first drain region having a generally rectangular shape; arranging sides of first, second, third and fourth source regions, which have a generally rectangular shape, adjacent to sides of the first drain region; arranging a gate region between the first, second, third and fourth source regions and the first drain region; and arranging first, second, third and fourth substrate contact regions adjacent to corners of the first drain region. 
     In other features, the first, second, third and fourth source regions have a length that is substantially equal to a length of the drain region. The first, second, third and fourth source regions have a width that is less than a width of the first drain region. The width of the first, second, third and fourth source regions is approximately one-half the width of the first drain region. 
     In other features, the method includes arranging one side of a second drain region, which has a generally rectangular shape, adjacent to the first source region; and arranging fifth, sixth and seventh source regions, which have a generally rectangular shape, adjacent to other sides of the second drain region. The method includes arranging a gate region between the first, fifth, sixth and seventh source regions and the second drain region. The method includes arranging fifth and sixth substrate contact regions adjacent to corners of the second drain region. The integrated circuit includes laterally-diffused MOSFET transistors. 
     An integrated circuit comprises a first drain region having a symmetric shape across at least one of horizontal and vertical centerlines. A first gate region has a first shape that surrounds the first drain region. A second drain region has the symmetric shape. A second gate region has the first shape that surrounds the second drain region. A connecting gate region connects the first and second gate regions. A first source region is arranged adjacent to and on one side of the first gate region, the second gate region and the connecting gate region. A second source region is arranged adjacent to and on one side of side of the first gate region, the second gate region and the connecting gate region. 
     In other features, the symmetric shape tapers as a distance from a center of the symmetric shape increases. First and second substrate contacts are arranged in the first and second source regions. The integrated circuit includes laterally-diffused MOSFET transistors. 
     In other features, the symmetric shape is a circular shape. The symmetric shape is an elliptical shape. The symmetric shape is a polygonal shape. The symmetric shape is a hexagonal shape. 
     A method for providing an integrated circuit comprises providing a first drain region having a symmetric shape across at least one of horizontal and vertical centerlines; providing a first gate region having a first shape that surrounds the first drain region; providing a second drain region having the symmetric shape; providing a second gate region having the first shape that surrounds the second drain region; connecting a connecting gate region to the first and second gate regions; arranging a first source region adjacent to and on one side of the first gate region, the second gate region and the connecting gate region; and arranging a second source region adjacent to and on one side of side of the first gate region, the second gate region and the connecting gate region. 
     In other features, the symmetric shape tapers as a distance from a center of the symmetric shape increases. In other features, the method includes arranging first and second substrate contacts in the first and second source regions. The integrated circuit includes laterally-diffused MOSFET transistors. 
     In other features, the symmetric shape is a circular shape. The symmetric shape is an elliptical shape. The symmetric shape is a polygonal shape. The symmetric shape is a hexagonal shape. 
     An integrated circuit comprises first and second drain regions having a generally rectangular shape. First, second and third source regions that have a generally rectangular shape, wherein the first source region is arranged between first sides of the first and second drain regions and the second and third source regions are arranged adjacent to second sides of the first and second drain regions. A fourth source region is arranged adjacent to third sides of the first and second drain regions. A fifth source region is arranged adjacent to fourth sides of the first and second drain regions. A gate region is arranged between the first, second, third, fourth and fifth source regions and the first and second drain regions. First and second drain contacts are arranged in the first and second drain regions. 
     A method for providing an integrated circuit comprises providing first and second drain regions having a generally rectangular shape; arranging a first source region between first sides of the first and second drain regions; arranging second and third source regions adjacent to second sides of the first and second drain regions; arranging a fourth source region adjacent to third sides of the first and second drain regions; arranging a fifth source region adjacent to fourth sides of the first and second drain regions; arranging a gate region between the first, second, third, fourth and fifth source regions and the first and second drain region; and arranging first and second drain contacts in the first and second drain regions. 
     In other features of the integrated circuit and method, the first, second and third source regions have a length that is substantially equal to a length of the first drain region and wherein the fourth and fifth source regions have a length that is greater than or equal to a length of the first and second drain regions. The first, second and third source regions have a width that is less than a width of the first drain region. The width of the first, second and third source regions is approximately one-half the width of the first drain region. The fourth and fifth source regions are driven from sides thereof. The first and second drain contacts have a size that is greater than a minimum drain contact size. The drain contacts have one of a regular shape and an irregular shape. The drain contacts are one of square, rectangular, and cross-shaped. The first, second and third source regions include source contacts. The first and second drain regions and the firs, second and third source regions are arranged in a first row and further comprising N additional rows, wherein drain regions of at least one of the N additional rows share one of the fourth and fifth source regions. 
     An integrated circuit comprises first and second drain regions having a generally rectangular shape. First, second and third source regions that have a generally rectangular shape, wherein the first source region is arranged between first sides of the first and second drain regions and the second and third source regions are arranged adjacent to second sides of the first and second drain regions. A fourth source region is arranged adjacent to third sides of the first and second drain regions. A fifth source region is arranged adjacent to fourth sides of the first and second drain regions. A gate region is arranged between the first, second, third, fourth and fifth source regions and the first and second drain regions. First and second drain contacts are arranged in the first and second drain regions. 
     A method for providing an integrated circuit comprises providing first and second drain regions having a generally rectangular shape; arranging a first source region between first sides of the first and second drain regions; arranging second and third source regions adjacent to second sides of the first and second drain regions; arranging a fourth source region adjacent to third sides of the first and second drain regions; arranging a fifth source region adjacent to fourth sides of the first and second drain regions; arranging a gate region between the first, second, third, fourth and fifth source regions and the first and second drain region; and arranging first and second drain contacts in the first and second drain regions. 
     In other features of the integrated circuit and method, the first, second and third source regions have a length that is substantially equal to a length of the first drain region and wherein the fourth and fifth source regions have a length that is greater than or equal to a length of the first and second drain regions. The first, second and third source regions have a width that is less than a width of the first drain region. The width of the first, second and third source regions is approximately one-half the width of the first drain region. The fourth and fifth source regions are driven from sides thereof. The first and second drain contacts have a size that is greater than a minimum drain contact size. The drain contacts have one of a regular shape and an irregular shape. The drain contacts are one of square, rectangular, and cross-shaped. The first, second and third source regions include source contacts. The first and second drain regions and the first, second and third source regions are arranged in a first row and further comprising N additional rows, wherein drain regions of at least one of the N additional rows share one of the fourth and fifth source regions. 
     Further regions of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present invention will become more fully understood from the detailed description and the accompanying drawings, wherein: 
         FIG. 1  is an electrical symbol for a transistor with a drain, source, gate and body according to the prior art; 
         FIG. 2  is an electrical symbol for a transistor with a drain, source, gate and body, which is connected to the source according to the prior art; 
         FIG. 3  is an exemplary layout of the transistor of  FIG. 2  according to the prior art; 
         FIG. 4  is an exemplary layout of multiple transistors that are arranged in a row according to the prior art; 
         FIG. 5A  is a first exemplary layout of transistors including a body that is arranged in the source; 
         FIG. 5B  is a second exemplary layout of transistors including a body having edges that align with the gates in plan view; 
         FIG. 6  is a second exemplary layout of transistors including a body that is arranged in the source; 
         FIG. 7  is a third exemplary layout of transistors including a body that is arranged in the source; 
         FIG. 8  is a fourth exemplary layout of transistors including a body that is arranged in the source; 
         FIG. 9  is a fifth exemplary layout of transistors including a body that is arranged in the source; 
         FIG. 10  is a cross-sectional view of a PMOS transistor according to the prior art; 
         FIG. 11  is a plan view of a sixth exemplary layout including well substrate contacts; 
         FIG. 12A  is a plan view of a seventh exemplary layout for reducing R DSon ; 
         FIG. 12B  is a plan view of the seventh exemplary layout of  FIG. 12A ; 
         FIG. 12C  is a plan view of an eighth exemplary layout for reducing R DSon ; 
         FIG. 12D  is a plan view of a ninth exemplary layout for reducing R DSon  that is similar to  FIG. 12C ; 
         FIG. 12E  is a plan view of a tenth exemplary layout for reducing R DSon  that is similar to  FIG. 12C ; 
         FIGS. 12F-12I  illustrate other exemplary drain contacts; 
         FIG. 13  is a plan view of a eleventh exemplary layout for reducing R DSon ; and; 
         FIG. 14  is a plan view of a twelfth exemplary layout for reducing R DSon ; 
         FIG. 15  is a plan view of a thirteenth exemplary layout for reducing R DSon ; 
         FIG. 16A  is a functional block diagram of a hard disk drive; 
         FIG. 16B  is a functional block diagram of a DVD drive; 
         FIG. 16C  is a functional block diagram of a high definition television; 
         FIG. 16D  is a functional block diagram of a vehicle control system; 
         FIG. 16E  is a functional block diagram of a cellular phone; 
         FIG. 16F  is a functional block diagram of a set top box; and 
         FIG. 16G  is a functional block diagram of a media player. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The following description of the preferred embodiment(s) is merely exemplary in nature and is in no way intended to limit the invention, its application, or uses. For purposes of clarity, the same reference numbers will be used in the drawings to identify the same elements. Additional transistors can be arranged on one or more sides of the illustrated transistors that are shown in the FIGs. as indicated by “ . . . ” in the FIGs. 
     Referring now to  FIGS. 5A and 5B , a transistor  50  according to the present invention is shown to include one or more sources  54  and one or more drains  56 . The sources  54  and the drains  56  include n +  regions. While an NMOS transistor is shown, skilled artisans will appreciate that the present invention also applies to other types of transistors such as PMOS transistors. Gates  58  are located between adjacent pairs of sources  54  and drains  56 . In one implementation, the gates  58  that are located on opposite sides of the sources  54  are connected together as shown at  64 . In other configurations, however, the gates  58  need not be connected together. 
     A body  66  including a p +  region is arranged inside of and is surrounded by the source  54 . The body  66  preferably has a shape that tapers as a distance between a midportion of the body  66  and adjacent gates decreases. The body  66  may touch or not touch the gates  58  in the plan views of  FIGS. 5A and 5B . In other words, one or both edges of the body  66  may be spaced from the gates  58  in plan view (as shown in  FIG. 5A ) and/or substantially aligns with the gates in plan view (as shown in  FIG. 5B ). By utilizing some of the area of the source  54  for the body  66 , the overall size of the transistor  50  is reduced as compared to conventional transistors. In the exemplary implementation that is shown in  FIG. 5 , the body  66  has a diamond shape. 
     Referring now to  FIGS. 6 and 7 , other exemplary shapes for the body  66  are shown. In  FIG. 6 , the body  66  has a hexagon shape. In  FIG. 7 , the body is generally football shaped. Skilled artisans will appreciate that there are a wide variety of other suitable shapes. For example, a circular body is shown in  FIG. 8 , which is described. Other suitable shapes include an ellipse, an octagon, etc. 
     Referring now to  FIGS. 8 and 9 , the gates  58  can be arranged such that they are closer together when there are no contact taps and further apart when there are contact taps. In  FIG. 8 , a source contact tap  70 , which is not located in the body  66 , is located in a region where the adjacent gates  58  are located farther apart. In  FIG. 9 , a body contact tap  80 , which is located in the body  66 , is located in the source  54  where the adjacent gates  58  are located farther apart. 
     Referring now to  FIG. 10 , a PMOS transistor  120  is shown. The transistor  120  includes a gate contact  122 , a source contact  126 , a drain contact  128  and a negative (N)-well contact  130 . The source contact  126  provides a connection to a P++ region  134  formed an N-type substrate layer  138 . The N-type layer  138 , in turn, is formed in a P-type substrate  140 . The P++ region  134  forms the source. The drain contact  128  provides an electrical connection to a P++ region  136  formed in the N-type layer  138 . The P++ region  136  forms the drain. The N-well contact  130  provides a connection to an N++ region  141  or N-well. 
     Referring now to  FIG. 11 , a plan view of a sixth exemplary layout is shown. For some transistor designs such as PMOS and/or NMOS transistors, electrostatic discharge (ESD) is less important than other design criteria. Therefore, N-well contact areas can be minimized. For PMOS transistors, the N-well contact area may be approximately 2.5 to 3 times the area in NMOS transistors. The source-drain resistance may be less important. Therefore, the layout in  FIG. 11  minimizes the N-well contact areas and the source-drain area. Skilled artisans will appreciate that while the foregoing description relates to PMOS transistors, similar principles apply to NMOS transistors. 
     In a layout shown in  FIG. 11 , gate regions  200 - 1 ,  200 - 2 , . . . , and  200 -G (collectively gate regions or gates  200 ) are defined between source regions  224 - 1 ,  224 - 2 , . . . , and  224 -S (collectively source regions  224 ) and drain regions  220 - 1 ,  220 - 2 , . . . , and  220 -D (collectively drain regions  220 ). Adjacent gates  200 - 1  and  200 - 2  define regions  210  having a wider width than adjacent regions  212  having narrower widths. Drain regions  220  and source regions  224  are alternately defined between the adjacent gates  200 . 
     Groups of transistors  230 - 11 ,  230 - 12 , . . . , and  230 -XY (collectively groups of transistors  230 ) are arranged adjacent to each other. Adjacent groups of transistors  230  share R N-well contacts  260 , where R is an integer greater than one. The R N-well contacts  260  can be located between the adjacent groups of transistors  230  in regions  210  where the gates  200  are spaced further apart. 
     The source-drain area is minimized by this layout. For example, each group may include 4-6 transistors. The R N-well contacts  260  are provided for adjacent groups in both vertical and horizontal directions. Therefore, abutting edges of the adjacent groups without the R N-well contacts  260  can be located in regions  212  where the gates are spaced closer together. In other words, the gates  200  can be arranged closer together to minimize areas of the regions  212  without the R N-well contacts  260 . 
     Referring now to  FIG. 12A , an exemplary high-density layout for laterally diffused MOSFET (LDMOS) transistors  300  is shown. The layout tends to reduce turn-on drain-source resistance R DSon . The transistors  300  include source (S) regions  304 , drain (D) regions  306  and gates  310 . Some, none or all of the source regions  304  may include one or more source contacts  311 . For illustration purposes, not all of the source regions  304  are shown with source contacts  311 . 
     The gates  310  define a checkerboard pattern. Source regions  304  are arranged along sides of the drain regions  306 . More particularly, the drain regions  306  may have a generally rectangular shape. The source regions  304  may be arranged along each side of the generally rectangular drain regions  306 . Substrate contacts  330  may be provided adjacent to corners of the drain regions  306  at intersections between adjacent source regions  304 . Drain contacts  334  may also be provided at a central location within the drain regions  306 . 
     Each drain region  306  may be arranged adjacent to source regions  304  that are common with other adjacent drain regions  306 . For example in dotted area  331  in  FIG. 12A , drain region  306 - 1  shares the source region  304 - 1  with the drain region  306 - 2 . Drain region  306 - 1  shares the source region  304 - 2  with the drain region  306 - 3 . Drain region  306 - 1  shares the source region  304 - 3  with the drain region  306 - 4 . Drain region  306 - 1  shares the source region  304 - 4  with the drain region  306 - 5 . This pattern may be repeated for adjacent drain regions  306 . 
     Each of the drain regions  306  may have an area that is greater than or equal to two times the area of each of the source regions  304 . In  FIG. 12A , the drain regions  306  have a width “b” and a height “a”. The source regions  304  have a width (or height) “d” and a height (or width) “c”. The drain regions  306  may have substantially the same length as the source regions  304 . The drain regions  306  may have greater than or equal to two times the width of the source regions  304 . 
     Referring now to  FIG. 12B , a more detailed view of part of the layout of  FIG. 12A  is shown. Drain contacts  334 - 1  and  334 - 3  may be associated with drain regions  306 - 1  and  306 - 3 , respectively. Substrate contacts  330  are located adjacent to corners of the drain regions  306 - 1 . Source contacts  311 - 1 ,  311 - 2 , . . . and  311 -B may be arranged in source regions  304 - 2  and  304 - 4 , where B is an integer. Drain contacts  334 - 1  and  334 - 3  may be arranged in each of the drain regions  306 - 1  and  306 - 3 , respectively. Drain contact  334 - 1  may define an area that is greater than the area of the source contact  311 - 1  in the source region  304 - 2 . 
     Substantially all of the current flowing between the drain region  306 - 3  and the source contacts  311 - 1 ,  311 - 2 , . . . and  311 -B of the adjacent source region  304 - 2  flows between a facing portion  335  of the drain contact  334 - 3  and facing halves  337 - 1 ,  337 - 2 , . . . and  337 -S of source contacts  311 - 1 ,  311 - 2 , . . . and  311 -B in the source region  304 - 2 . Current flows in a similar manner between other facing portions of the drain contact  334 - 3  and source contacts (not shown) in other adjacent source regions  304 - 5 ,  304 - 6  and  304 - 7 . 
     Referring now to  FIG. 12C , another exemplary high-density layout for laterally diffused MOSFET (LDMOS) transistors  340  is shown. The layout tends to provide low turn-on drain-source resistance R DSon . The transistors  340  include source regions  304 - 11 ,  304 - 12 , . . .  304 - 4 Q, drain regions  306 - 11 ,  306 - 12 , . . .  306 - 4 T and gates  310 , where Q and T are integers. While four rows are shown in  FIG. 12B , additional and/or fewer rows and/or columns may be employed. Some, none or all of the source regions  304  may include source contacts  311 . For illustration purposes, not all of the source regions  304  are shown with source contacts. For example, source region  304 - 12  includes source contacts  311 - 1 ,  311 - 2 , . . . and  311 -B, where B is an integer. 
     Other elongated source regions  344 - 1 ,  344 - 2 ,  344 - 3 , . . . and  344 -R are arranged between rows (or columns) of drain regions  306  and may be driven by drivers  346 - 1 ,  346 - 2 , . . . , and  346 -R arranged on one or both sides (or tops) of the layout in  FIG. 12B . The elongated source regions  344 - 1 ,  344 - 2 ,  344 - 3 , . . . and  344 -R may extend adjacent to sides of at least two drain regions  306  such as at least drain regions  306 - 11  and  306 - 12 . 
     Each of the drain regions  306  (such as drain region  306 - 11 ) may have an area that is greater than or equal to two times the area of each of the source regions  304  (such as source region  304 - 12 ). The drain regions  306  (such as drain region  306 - 11 ) may have substantially the same length as the source regions  304  (such as source region  304 - 12 ). The drain regions  306  (such as drain region  306 - 11 ) may have greater than or equal to two times the width of the source regions  304  (such as source region  304 - 12 ). 
     Substrate contacts  347 - 11 ,  347 - 12 ,  347 - 21 ,  347 - 22 ,  347 - 23 , . . .  347 - 51 ,  347 - 52  (collectively substrate contacts  347 ) may be arranged in some, none or all of the elongated source regions  344 . The placement and number of substrate contracts  347  may be uniform or varied for each of the elongated source regions  344 . For example only, the substrate contacts  347  shown in  FIG. 12C  may be offset from the substrate contacts  347  in adjacent elongated source regions  344 . Each of the elongated source regions  344  may include the same number or a different number of substrate contacts  347  than adjacent elongated source regions  344 . The substrate contacts  347  may be aligned or offset as shown. Some elongated source regions  344  may include no substrate contacts  347 . Still other variations are contemplated. 
     Referring now to  FIG. 12D , first areas  345 -A 1 ,  345 -A 2 ,  345 -A 3  and  345 -A 4  may provide useful transistor areas. For example, first areas  345 -A 1 ,  345 -A 2 ,  345 -A 3  and  345 -A 4  may be located between drain region  306 - 12  and source regions  304 - 12 ,  344 - 1 ,  304 - 13 , and  344 - 2 , respectively. Second areas  345 -B 1 ,  345 -B 2 ,  345 -B 3  and  345 -B 4  may provide less useful transistor areas. For example, second areas  345 -B 1 ,  345 -B 2 ,  345 -B 3  and  345 -B 4  may be located between source regions  304 - 12 ,  344 - 1 ,  304 - 13 , and  344 - 2 . 
     In some implementations, the substrate contacts  347 - 11 ,  347 - 12 ,  347 - 21 ,  347 - 22 ,  347 - 23 , . . . may be arranged in some, none or all of the second areas  345 -B 1 ,  345 -B 2 ,  345 -B 3  and  345 -B 4  of the source regions  344 - 1 ,  344 - 2 , . . . and  344 -R, for example as shown in  FIG. 12D . The substrate contacts  347 - 11 ,  347 - 12 ,  347 - 21 ,  347 - 22 ,  347 - 23 , . . . are shown arranged in the elongated substrate regions  344 - 1  and  344 - 2  and tend to lower R DS     —     ON . The substrate contacts  347 - 11 ,  347 - 12 ,  347 - 21 ,  347 - 22 ,  347 - 23 , . . . may have a height that is less than or equal to a width “c” of the source regions  304  (as shown in  FIG. 12A ) and a width that is less than or equal to a width “d” of the source regions  304  (as shown in  FIG. 12A ). 
     Referring now to  FIG. 12E , substrate contacts  330 - 1  and  330 - 2  are provided between pairs of elongated source regions  344 - 1 A and  344 - 1 B and  344 - 2 A and  344 - 2 B, respectively. The elongated source regions  344 - 1 A and  344 - 2 A are driven from one side by drivers  346 - 1 A and  346 - 2 A. The elongated source regions  344 - 1 B and  344 - 2 B are driven from another side by drivers  346 - 1 B and  346 - 2 B. 
     Drain contacts  334  in  FIGS. 12A-12E  may have a minimum size or a size that is greater than the minimum size. Drain contacts  334  may have a simple or regular shape and/or an irregular or complex shape. For example, the drain contacts  334  may have a square or rectangular shape (as shown at  344  in  FIG. 12A ), a cross shape (as shown at  344 -W in  FIG. 12F ), clover-leaf shapes (as shown at  334 -X and  334 -Y in  FIGS. 12G and 12H , respectively), a modified cross-shaped region (as shown at  334 -Z in  FIG. 12I ) and/or other suitable shapes such as but not limited to diamond, circular, symmetric, non-symmetric, etc. The substrate contacts  347  may similarly have a simple or regular shape and/or an irregular or complex shape similar to the drain contacts  334 . 
     In some implementations, the number of source contacts B in a given source region may be an integer that is greater than one and less than six. In some implementations, B may be equal to 3 or 4. The area of the drain contact  334 - 3  may be greater than or equal to 2*B* (the area one of source contacts  311 - 1 ,  311 - 2 , . . . or  311 -B). For example, when B is equal to 3, the drain contact region  334 - 3  may have an area that is approximately greater than or equal to 6 times an area of one source contact  311 - 1 ,  311 - 2 , . . . or  311 -B. When B is equal to 4, the drain contact region  334 - 3  may an area that is approximately greater than or equal to 8 times an area of one source contact  311 - 1 ,  311 - 2 , . . . or  311 -B. 
     As the size of the drain contacts  334  increases relative to the corresponding drain region  306 , over-etching may occur. In other words, the etching process may adversely impact adjacent regions and/or underlying layers. To alleviate the problems of over-etching, the complex shapes in  FIGS. 12F-12I  and/or other complex shapes can be employed for the drain contacts  334 . Alternately, the drain contacts  334  can employ deep implant ions in and/or below the drain contacts  334 . 
     As an alternative to placing the substrate contact  330  in the elongated source regions  344 , a relief area may be provided in one or both sides of the source region  344  in areas  345 -B 1 ,  345 -B 2 ,  345 -B 3  and  345 -B. A substrate contact region  330  can be positioned in the relief area. The shape of the elongate source region  344  can be adjusted on an opposite side of the relief area to offset the effect of the relief area and to prevent reduction in current density in areas of the elongate source region  344  near the relief areas. 
     Referring now to  FIGS. 13-15 , drain, source and gate regions can also have other shapes that can be used to minimize R DSON . For example, drain regions  348  can have a circular shape as shown in  FIG. 13 , an elliptical shape as shown in  FIG. 14  and/or other suitable shapes. Gate regions  349  include circular-shaped gate regions  350  that are connected by linear gate connecting regions  352 . Similar elements are identified in  FIG. 14  using a prime symbol (“′”). The drain regions  348  are located in the circular-shaped gate regions  350 . Source regions  360  are located in between the gate regions  349  in areas other than the inside of the circular shaped gate regions  350 . Substrate contacts  364  are located in the source regions  360 . The drain regions  348  may also include a contact region  366 . The linear gate regions  352  may have a vertical spacing “g” that is minimized to increase density. Likewise, lateral spacing identified at “f” between adjacent circular-shaped gate regions  350  may be minimized to increase density. 
     Drain areas  368  can also have polygon shapes. For example, the drain areas can have a hexagon shape as shown in  FIG. 15 , although other polygon shapes can be used. Gate regions  369  include hexagon-shaped gate regions  370  that are connected by linear gate connecting regions  372 . The drain regions  368  are located in the hexagon-shaped gate regions  370 . Source regions  380  are located in between the gate regions  369  in areas other than the inside of the hexagon-shaped gate regions  370 . Substrate contacts  384  are located in the source regions  380 . The drain regions may also include a contact region  386 . The linear gate connecting regions  372  preferably have a vertical spacing “j” that is minimized to increase density. Likewise lateral spacing identified at “i” between adjacent hexagon-shaped gate regions  370  is minimized to increase density. 
     As can be appreciated, the shapes for the drain and gate areas in  FIGS. 13-15  can be any shape that is symmetric about at least one of the horizontal and vertical centerlines of the drain areas. The transistors in  FIGS. 13-15  may be LDMOS transistors. The shape of the drain regions may include any symmetric shape. The shape may taper as a distance from a center point of the drain area increases and/or as a center point of the drain area increases in a direction towards one or more other transistors. 
     Referring now to  FIGS. 16A-16G , various exemplary implementations incorporating the teachings of the present disclosure are shown. 
     Referring now to  FIG. 16A , the teachings of the disclosure can be implemented in a transistors of a hard disk drive (HDD)  400 . The HDD  400  includes a hard disk assembly (HDA)  401  and a HDD PCB  402 . The HDA  401  may include a magnetic medium  403 , such as one or more platters that store data, and a read/write device  404 . The read/write device  404  may be arranged on an actuator arm  405  and may read and write data on the magnetic medium  403 . Additionally, the HDA  401  includes a spindle motor  406  that rotates the magnetic medium  403  and a voice-coil motor (VCM)  407  that actuates the actuator arm  405 . A preamplifier device  408  amplifies signals generated by the read/write device  404  during read operations and provides signals to the read/write device  404  during write operations. 
     The HDD PCB  402  includes a read/write channel module (hereinafter, “read channel”)  409 , a hard disk controller (HDC) module  410 , a buffer  411 , nonvolatile memory  412 , a processor  413 , and a spindle/VCM driver module  414 . The read channel  409  processes data received from and transmitted to the preamplifier device  408 . The HDC module  410  controls components of the HDA  401  and communicates with an external device (not shown) via an I/O interface  415 . The external device may include a computer, a multimedia device, a mobile computing device, etc. The I/O interface  415  may include wireline and/or wireless communication links. 
     The HDC module  410  may receive data from the HDA  401 , the read channel  409 , the buffer  411 , nonvolatile memory  412 , the processor  413 , the spindle/VCM driver module  414 , and/or the I/O interface  415 . The processor  413  may process the data, including encoding, decoding, filtering, and/or formatting. The processed data may be output to the HDA  401 , the read channel  409 , the buffer  411 , nonvolatile memory  412 , the processor  413 , the spindle/VCM driver module  414 , and/or the I/O interface  415 . 
     The HDC module  410  may use the buffer  411  and/or nonvolatile memory  412  to store data related to the control and operation of the HDD  400 . The buffer  411  may include DRAM, SDRAM, etc. The nonvolatile memory  412  may include flash memory (including NAND and NOR flash memory), phase change memory, magnetic RAM, or multi-state memory, in which each memory cell has more than two states. The spindle/VCM driver module  414  controls the spindle motor  406  and the VCM  407 . The HDD PCB  402  includes a power supply  416  that provides power to the components of the HDD  400 . 
     Referring now to  FIG. 16B , the teachings of the disclosure can be implemented in a transistors of a DVD drive  418  or of a CD drive (not shown). The DVD drive  418  includes a DVD PCB  419  and a DVD assembly (DVDA)  420 . The DVD PCB  419  includes a DVD control module  421 , a buffer  422 , nonvolatile memory  423 , a processor  424 , a spindle/FM (feed motor) driver module  425 , an analog front-end module  426 , a write strategy module  427 , and a DSP module  428 . 
     The DVD control module  421  controls components of the DVDA  420  and communicates with an external device (not shown) via an I/O interface  429 . The external device may include a computer, a multimedia device, a mobile computing device, etc. The I/O interface  429  may include wireline and/or wireless communication links. 
     The DVD control module  421  may receive data from the buffer  422 , nonvolatile memory  423 , the processor  424 , the spindle/FM driver module  425 , the analog front-end module  426 , the write strategy module  427 , the DSP module  428 , and/or the I/O interface  429 . The processor  424  may process the data, including encoding, decoding, filtering, and/or formatting. The DSP module  428  performs signal processing, such as video and/or audio coding/decoding. The processed data may be output to the buffer  422 , nonvolatile memory  423 , the processor  424 , the spindle/FM driver module  425 , the analog front-end module  426 , the write strategy module  427 , the DSP module  428 , and/or the I/O interface  429 . 
     The DVD control module  421  may use the buffer  422  and/or nonvolatile memory  423  to store data related to the control and operation of the DVD drive  418 . The buffer  422  may include DRAM, SDRAM, etc. The nonvolatile memory  423  may include flash memory (including NAND and NOR flash memory), phase change memory, magnetic RAM, or multi-state memory, in which each memory cell has more than two states. The DVD PCB  419  includes a power supply  430  that provides power to the components of the DVD drive  418 . 
     The DVDA  420  may include a preamplifier device  431 , a laser driver  432 , and an optical device  433 , which may be an optical read/write (ORW) device or an optical read-only (OR) device. A spindle motor  434  rotates an optical storage medium  435 , and a feed motor  436  actuates the optical device  433  relative to the optical storage medium  435 . 
     When reading data from the optical storage medium  435 , the laser driver provides a read power to the optical device  433 . The optical device  433  detects data from the optical storage medium  435 , and transmits the data to the preamplifier device  431 . The analog front-end module  426  receives data from the preamplifier device  431  and performs such functions as filtering and A/D conversion. To write to the optical storage medium  435 , the write strategy module  427  transmits power level and timing information to the laser driver  432 . The laser driver  432  controls the optical device  433  to write data to the optical storage medium  435 . 
     Referring now to  FIG. 16C , the teachings of the disclosure can be implemented in a transistors of a high definition television (HDTV)  437 . The HDTV  437  includes a HDTV control module  438 , a display  439 , a power supply  440 , memory  441 , a storage device  442 , a WLAN interface  443  and associated antenna  444 , and an external interface  445 . 
     The HDTV  437  can receive input signals from the WLAN interface  443  and/or the external interface  445 , which sends and receives information via cable, broadband Internet, and/or satellite. The HDTV control module  438  may process the input signals, including encoding, decoding, filtering, and/or formatting, and generate output signals. The output signals may be communicated to one or more of the display  439 , memory  441 , the storage device  442 , the WLAN interface  443 , and the external interface  445 . 
     Memory  441  may include random access memory (RAM) and/or nonvolatile memory such as flash memory, phase change memory, or multi-state memory, in which each memory cell has more than two states. The storage device  442  may include an optical storage drive, such as a DVD drive, and/or a hard disk drive (HDD). The HDTV control module  438  communicates externally via the WLAN interface  443  and/or the external interface  445 . The power supply  440  provides power to the components of the HDTV  437 . 
     Referring now to  FIG. 16D , the teachings of the disclosure may be implemented in a transistors of a vehicle  446 . The vehicle  446  may include a vehicle control system  447 , a power supply  448 , memory  449 , a storage device  450 , and a WLAN interface  452  and associated antenna  453 . The vehicle control system  447  may be a powertrain control system, a body control system, an entertainment control system, an anti-lock braking system (ABS), a navigation system, a telematics system, a lane departure system, an adaptive cruise control system, etc. 
     The vehicle control system  447  may communicate with one or more sensors  454  and generate one or more output signals  456 . The sensors  454  may include temperature sensors, acceleration sensors, pressure sensors, rotational sensors, airflow sensors, etc. The output signals  456  may control engine operating parameters, transmission operating parameters, suspension parameters, etc. 
     The power supply  448  provides power to the components of the vehicle  446 . The vehicle control system  447  may store data in memory  449  and/or the storage device  450 . Memory  449  may include random access memory (RAM) and/or nonvolatile memory such as flash memory, phase change memory, or multi-state memory, in which each memory cell has more than two states. The storage device  450  may include an optical storage drive, such as a DVD drive, and/or a hard disk drive (HDD). The vehicle control system  447  may communicate externally using the WLAN interface  452 . 
     Referring now to  FIG. 16E , the teachings of the disclosure can be implemented in a transistors of a cellular phone  458 . The cellular phone  458  includes a phone control module  460 , a power supply  462 , memory  464 , a storage device  466 , and a cellular network interface  467 . The cellular phone  458  may include a WLAN interface  468  and associated antenna  469 , a microphone  470 , an audio output  472  such as a speaker and/or output jack, a display  474 , and a user input device  476  such as a keypad and/or pointing device. 
     The phone control module  460  may receive input signals from the cellular network interface  467 , the WLAN interface  468 , the microphone  470 , and/or the user input device  476 . The phone control module  460  may process signals, including encoding, decoding, filtering, and/or formatting, and generate output signals. The output signals may be communicated to one or more of memory  464 , the storage device  466 , the cellular network interface  467 , the WLAN interface  468 , and the audio output  472 . 
     Memory  464  may include random access memory (RAM) and/or nonvolatile memory such as flash memory, phase change memory, or multi-state memory, in which each memory cell has more than two states. The storage device  466  may include an optical storage drive, such as a DVD drive, and/or a hard disk drive (HDD). The power supply  462  provides power to the components of the cellular phone  458 . 
     Referring now to  FIG. 16F , the teachings of the disclosure can be implemented in a transistors of a set top box  478 . The set top box  478  includes a set top control module  480 , a display  481 , a power supply  482 , memory  483 , a storage device  484 , and a WLAN interface  485  and associated antenna  486 . 
     The set top control module  480  may receive input signals from the WLAN interface  485  and an external interface  487 , which can send and receive information via cable, broadband Internet, and/or satellite. The set top control module  480  may process signals, including encoding, decoding, filtering, and/or formatting, and generate output signals. The output signals may include audio and/or video signals in standard and/or high definition formats. The output signals may be communicated to the WLAN interface  485  and/or to the display  481 . The display  481  may include a television, a projector, and/or a monitor. 
     The power supply  482  provides power to the components of the set top box  478 . Memory  483  may include random access memory (RAM) and/or nonvolatile memory such as flash memory, phase change memory, or multi-state memory, in which each memory cell has more than two states. The storage device  484  may include an optical storage drive, such as a DVD drive, and/or a hard disk drive (HDD). 
     Referring now to  FIG. 16G , the teachings of the disclosure can be implemented in a transistors of a media player  489 . The media player  489  may include a media player control module  490 , a power supply  491 , memory  492 , a storage device  493 , a WLAN interface  494  and associated antenna  495 , and an external interface  499 . 
     The media player control module  490  may receive input signals from the WLAN interface  494  and/or the external interface  499 . The external interface  499  may include USB, infrared, and/or Ethernet. The input signals may include compressed audio and/or video, and may be compliant with the MP3 format. Additionally, the media player control module  490  may receive input from a user input  496  such as a keypad, touchpad, or individual buttons. The media player control module  490  may process input signals, including encoding, decoding, filtering, and/or formatting, and generate output signals. 
     The media player control module  490  may output audio signals to an audio output  497  and video signals to a display  498 . The audio output  497  may include a speaker and/or an output jack. The display  498  may present a graphical user interface, which may include menus, icons, etc. The power supply  491  provides power to the components of the media player  489 . Memory  492  may include random access memory (RAM) and/or nonvolatile memory such as flash memory, phase change memory, or multi-state memory, in which each memory cell has more than two states. The storage device  493  may include an optical storage drive, such as a DVD drive, and/or a hard disk drive (HDD). 
     Those skilled in the art can now appreciate from the foregoing description that the broad teachings of the present invention can be implemented in a variety of forms. Therefore, while this invention has been described in connection with particular examples thereof, the true scope of the invention should not be so limited since other modifications will become apparent to the skilled practitioner upon a study of the drawings, the specification and the following claims.