Patent Publication Number: US-2020294993-A1

Title: Electrostatic discharge (esd) robust transistors and related methods

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation application of the earlier U.S. Utility Patent Application to Fujiwara et al. entitled “Electrostatic Discharge (ESD) Robust Transistors and Related Methods,” application Ser. No. 14/852,912, filed Sep. 14, 2015, now pending, the disclosure of which is hereby incorporated entirely herein by reference. 
    
    
     BACKGROUND 
     1. Technical Field 
     Aspects of this document relate generally to semiconductor transistors. 
     2. Background Art 
     A semiconductor transistor is a device used to amplify and/or switch an electronic signal. Semiconductor transistors may be subject to damage or altered behavior due to electrostatic discharge (ESD). There are a variety of models/standards that are used for designing and testing against transistor failure due to electrostatic discharge. These include the human body model (HBM), the charge device model (CDM) and the machine model (MM). The HBM simulates ESD due to discharge from a human being. The CDM simulates a charged device&#39;s discharge when it contacts a conductor. The MM simulates discharge from a non-human source to the device, such as from production equipment or a tool. 
     SUMMARY 
     Implementations of an electrostatic discharge (ESD) robust semiconductor transistor (transistor) may include: a semiconductor substrate of a first conductivity type; a substrate contact region of the first conductivity type coupled with the semiconductor substrate; a source region of a second conductivity type coupled with the semiconductor substrate; a channel region of the second conductivity type; a gate region of the first conductivity type; a drain region including a first drain region of the first conductivity type and a second drain region of the second conductivity type, and; an electrical conductor coupled over the second drain region and a portion of the first drain region; wherein a portion of the first drain region is not covered by the electrical conductor and becomes a resistive electrical ballast region configured to protect the transistor from electrostatic discharge (ESD) induced voltage pulses, and; wherein the transistor includes a silicon controlled rectifier junction field effect transistor (SCR JFET). 
     Implementations of an ESD robust semiconductor transistor may include one, all, or any of the following: 
     The first conductivity type may be P type conductivity, the second conductivity type may be N type conductivity, the channel region may include an N− channel region, and the transistor may include an N− channel SCR JFET. 
     The semiconductor substrate may include a P type substrate, the substrate contact region may include a P+ substrate contact region, the source region may include an N+ source region, the gate region may include a P+ gate region, the first drain region may include a P+ drain region, and the second drain region may include an N+ drain region. 
     The electrical conductor may include a silicide. 
     The resistive electrical ballast region may have a width of at least 3 microns. 
     The resistive electrical ballast region may form a separation layer between the electrical conductor and an electrically insulative region. 
     The transistor may have a stadium shape. 
     Implementations of an electrostatic discharge (ESD) robust semiconductor transistor (transistor) may include: a semiconductor substrate of a first conductivity type; a first substrate contact region of the first conductivity type coupled with the semiconductor substrate; a source region of a second conductivity type coupled with the semiconductor substrate; a channel region of the second conductivity type; a gate region of the first conductivity type; a drain region having a first drain region of the first conductivity type and a second drain region of the second conductivity type; a second substrate contact region of the second conductivity type coupled with the semiconductor substrate, and; an electrical conductor coupled over the second drain region and a portion of the first drain region; wherein a portion of the first drain region is not covered by the electrical conductor and becomes a resistive electrical ballast region configured to protect the transistor from electrostatic discharge (ESD) induced voltage pulses, and; wherein the transistor includes a silicon controlled rectifier junction field effect transistor (SCR JFET). 
     Implementations of an ESD robust semiconductor transistor may include one, all, or any of the following: 
     The first conductivity type may be P type conductivity and the second conductivity type may be N type conductivity, wherein the channel region includes an N− channel region, and wherein the SCR JFET includes an N− channel SCR JFET. 
     The semiconductor substrate may include a P type substrate, the first substrate contact region may include a P+ substrate contact region, the source region may include an N+ source region, the channel region may include an N− channel region, the gate region may include a P+ gate region, the first drain region may include a P+ drain region (P+ anode), the second drain region may include an N+ drain region, and the second substrate contact region may include an N+ substrate contact region (N+ cathode). 
     The electrical conductor may include a silicide. 
     The resistive electrical ballast region may have a width of at least 3 microns. 
     The resistive electrical ballast region may form a separation layer between the electrical conductor and an electrically insulative region. 
     The transistor may have a stadium shape. 
     Implementations of an electrostatic discharge (ESD) robust semiconductor transistor (transistor) may include: a semiconductor substrate of a first conductivity type; a substrate contact region of the first conductivity type coupled with the semiconductor substrate through a first well region of the first conductivity type, the first well region separating the substrate contact region from the semiconductor substrate; a source region of a second conductivity type coupled with the semiconductor substrate; a second well region of the second conductivity type coupled with the semiconductor substrate; a drain region having a first drain region of the first conductivity type and a second drain region of the second conductivity type; a gate region, and; a silicide coupled over the second drain region and a portion of the first drain region; wherein a portion of the first drain region is not covered by the silicide and becomes a resistive electrical ballast region having a width of at least 3 microns, the resistive electrical ballast region configured to protect the transistor from electrostatic discharge (ESD) induced voltage pulses, and; wherein the transistor includes a silicon controlled rectifier field effect transistor (SCR FET). 
     Implementations of an ESD robust semiconductor transistor may include one, all, or any of the following: 
     The SCR FET may include a laterally diffused metal-oxide semiconductor (SCR LDMOS) transistor. 
     The first conductivity type may be P type conductivity and the second conductivity type may be N type conductivity. 
     The semiconductor substrate may include a P type substrate, the substrate contact region may include a P+ substrate contact region, the first well region may include a P well region, the second well region may include an N well region, the source region may include an N+ source region, the gate region may include an N+ gate region, the first drain region may include a P+ drain region, and the second drain region may include an N+ drain region. 
     The first well region may fully separate the substrate contact region from the semiconductor substrate and the first well region may directly contact the semiconductor substrate. 
     The second well region may fully separate the first well region from the semiconductor substrate. 
     The foregoing and other aspects, features, and advantages will be apparent to those artisans of ordinary skill in the art from the DESCRIPTION and DRAWINGS, and from the CLAIMS. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Implementations will hereinafter be described in conjunction with the appended drawings, where like designations denote like elements, and: 
         FIG. 1  is a top view of an implementation of a semiconductor transistor; 
         FIG. 2  is a side cross-section view of the semiconductor transistor of  FIG. 1  taken along line A-A′; 
         FIG. 3  is an infrared microscope photograph of a close-up top view of a semiconductor transistor having the configuration of  FIG. 1  in a damaged state; 
         FIG. 4  is a close-up side cross-section view of a drain region of the semiconductor transistor of  FIG. 1 ; 
         FIG. 5  is a close-up side cross-section view of a drain region of an implementation of an electrostatic discharge (ESD) robust semiconductor transistor; 
         FIG. 6  is top and enlarged views of an implementation of an ESD robust semiconductor transistor; 
         FIG. 7  is a top view of an implementation of an ESD robust semiconductor transistor; 
         FIG. 8  is a side cross-section view of the ESD robust semiconductor transistor of  FIG. 7  taken along line A-A′; 
         FIG. 9  is a side cross-section view of an implementation of an ESD robust semiconductor transistor; 
         FIG. 10  is a side cross-section view of an implementation of an ESD robust semiconductor transistor, and; 
         FIG. 11  is a side cross-section view of an implementation of an ESD robust semiconductor transistor. 
     
    
    
     DESCRIPTION 
     This disclosure, its aspects and implementations, are not limited to the specific components, assembly procedures or method elements disclosed herein. Many additional components, assembly procedures and/or method elements known in the art consistent with the intended electrostatic discharge (ESD) robust transistors and related methods will become apparent for use with particular implementations from this disclosure. Accordingly, for example, although particular implementations are disclosed, such implementations and implementing components may comprise any shape, size, style, type, model, version, measurement, concentration, material, quantity, method element, step, and/or the like as is known in the art for such ESD robust transistors and related methods, and implementing components and methods, consistent with the intended operation and methods. 
     Referring now to  FIG. 1 , an implementation of a semiconductor transistor (transistor)  2  is shown. In the implementation shown the transistor is a silicon controlled rectifier junction field effect transistor (SCR JFET), though the transistor could have a different configuration/use. Similarly, in the implementation shown the transistor has a stadium shape, though in other implementations other closed shapes, such as circular, elliptical, or rectangular, could be used. 
       FIG. 2  is a cross-section view of the transistor of  FIG. 1  taken along line A-A. Referring now to  FIGS. 1-2 , the transistor  2  includes a semiconductor substrate  4 . In the implementation shown the substrate is a P type (p doped) substrate, though in other implementations other configurations (such as an N type (n doped) substrate) could be used. Thus, in the implementation shown the gate/channel/substrate forms a PNP configuration, though in other implementations this could be configured so that an NPN configuration is formed. 
     The configuration (P type, N type, etc.) of the semiconductor substrate may be manufactured using any number of doping, diffusion, and/or annealing steps, or the like, with a silicon substrate, by non-limiting example. As will be described below, the transistor further includes electrically insulative regions, drain regions, gate regions, source regions, substrate contact regions, and the like, each of which may have different electrical and/or other properties. The different regions may be formed by any number or combination of masking (photoresist), exposing, etching, washing, doping, implanting, diffusing, annealing, and/or other steps, using appropriate materials and dopants, and the like. 
     The transistor  2  includes source, gate, drain, and channel regions. The channel region may be an N− channel region  16 . The gate, source, and drain regions are all coupled with (and, in the implementations shown, are in direct contact with) the channel region, thus electrical current may flow between the source and drain through the channel and may be controlled by the gate. The source region (labeled “Source” in  FIG. 2 ) is an N+ source region  6  and is separated from the nearby gate region using an electrically insulative region  18 . The gate region (labeled “Gate” in  FIG. 2 ) is a P+ gate region  8 , thus the gate, channel and substrate form a PNP structure. 
     The drain region (labeled “Drain” in  FIG. 2 ) is separated from the gate region using an electrically insulative region  18 . The drain region includes both a P+ drain region  12  (P+ anode) and an N+ drain region  14 . A substrate contact region is also included (labeled “Sub” in  FIG. 2 ) and is separated from the source region with an electrically insulative region  18 . The substrate contact region in the implementation shown is a P+ substrate contact region  10 . 
     A number of electrically insulative regions  18  separate the source, gate and drain at the surface of the transistor. The electrically insulative regions may be formed of, by non-limiting example, SiO 2 , or any other electrically insulative material. 
     Although the various regions in the representative example are formed of particular material types, i.e., a P type substrate, N+ source region, P+ gate region, P+ substrate contact region, P+ drain region (P+ anode), N+ drain region, N− channel region, silicide region, and so forth, other material types and combinations could be chosen by the practitioner of ordinary skill having similar or different electrical or other properties as desired (for instance beginning with an N type substrate and choosing the other material types accordingly). 
       FIG. 3  is a top close-up view of an infrared microscope photograph of a transistor having the configuration of transistor  2  but having damaged regions  20  resulting from electrostatic discharge (ESD). As indicated above, there are a number of sources of ESD, including contact with a human body, discharge of a charged device itself, or discharge from a tool or production implement that comes into contact with the device. The device of  FIG. 3  was an 800 V SCR-JFET and was stressed with a single 2500 V HBM pulse.  FIG. 3  shows four damaged regions  20 . The upper two are filament-like failure spots at the channel region. There are also two damaged regions  20  in the drain region (within dotted-line circles). The dotted square of  FIG. 3  shows a non-damaged region  22 , and is simply metal routing of the transistor that appears darker in the infrared microscope photograph. Naturally, damaged areas, as those shown in  FIG. 3 , can lead to undesirable transistor operation or likely failure. 
       FIG. 4  is a close-up view of the drain region of transistor  2 . An electrical conductor  24  is shown laid over the P+ drain region  12  and over the N+ drain region  14 . The electrical conductor fully covers the P+ and N+ drain regions. In the implementation shown the electrical conductor is an electrically conductive silicide region, though in other implementations it could be formed of some other conductor, such as a metal layer. A number of electrically conductive leads  26  are coupled with the electrical conductor  24 , thus the drain region of transistor  2  may be in electrical communication with an external element or some other element through the electrical conductor and the electrically conductive leads. 
       FIG. 5  shows a close-up cross-section view of a drain region of an electrostatic discharge (ESD) robust semiconductor transistor (transistor)  28 . In the implementation shown the transistor  28  has many similarities to transistor  2  and is a silicon controlled rectifier junction field effect transistor (SCR JFET), though in other implementations transistor  28  could have some other configuration/use. 
       FIG. 5  illustrates that the drain region of transistor  28  is coupled with an N− channel region  42 . Electrically insulative regions  44  separate the drain region from other portions of the transistor. The electrically insulative regions  44  may be formed of any materials that electrically insulative regions  18  may be formed of. The drain region is seen as including a P+ drain region (P+ anode)  38  and an N+ drain region  40 . An electrical conductor  46  is laid over these two drain regions. The electrical conductor in the implementation shown is an electrically conductive silicide region, though in other implementations it could be formed of a metal or another electrically conductive element. Electrically conductive leads  48  couple with the electrical conductor  46  and may be used to electrically couple the drain region with an external element or some other device. 
     As can be seen from  FIG. 5 , the electrical conductor  46  of transistor  28  does not fully cover the P+ drain region  38 . Instead, a gap is left, which forms and/or becomes a resistive electrical ballast region (separation layer)  50 . This resistive electrical ballast region (separation layer)  50  may greatly enhances the ESD robustness of the transistor. 
       FIG. 6  shows a top view of an implementation of a transistor  28  having a first configuration in which the drain region forms a stadium shape and the source, gate, and other regions form circle shapes. A number of electrically insulative regions  44  separate the various other regions of the transistor. In the left side of  FIG. 6  is a close up magnified view that shows an N+ cathode region  52 , a P+ substrate contact region  36 , a gate region (which in the implementation shown is a P+ gate region  34 ), an N+ source region  32 , a P+ drain region  38  (P+ anode), and an electrical conductor  46 . 
     In the close-up view on the right hand side of  FIG. 6  the elements of the drain region are shown more closely and somewhat in see-through. The N+ drain region  40  is shown along with the P+ drain region  38 . The electrical conductor  46  completely covers the N+ drain region and a portion of the P+ drain region. Electrically conductive leads  48  are coupled with the electrical conductor  46 . A portion of one of the electrically insulative regions  44  is also shown in the close-up view. The resistive electrical ballast region (separation layer)  50  is that portion of the P+ drain region which is not covered with the electrical conductor  46 . 
       FIG. 7  shows a top view of another configuration for a transistor  28  in which the drain region and the other regions all form stadium shapes.  FIG. 7  shows various regions including an N+ cathode region  52 , a P+ substrate contact region  36 , an N+ source region  32 , a P+ gate region  34 , a P+ drain region  38 , an electrical conductor  46 , and a number of electrically insulative regions  44 . Shapes other than circles, stadiums and/or ellipses could be formed with the various elements of the transistor. 
       FIG. 8  is a side cross-section view of the transistor  28  of  FIG. 7  taken along line A-A. The semiconductor substrate  30  of transistor  28  is a P type substrate, and thus the gate/channel/substrate forms a PNP structure, but as described above with respect to transistor  2 , transistor  28  could be fabricated having an N type substrate and having an NPN gate/channel/substrate structure. Various configurations could be formed by a practitioner of ordinary skill in the art to form transistors which are different from those disclosed in the drawings but which include the resistive electrical ballast regions (separation layers)  50  to provide the ESD robustness. 
     An N+ cathode region  52  is included (leftmost item labeled “Sub” in  FIG. 8 ) and is coupled with (and, in the implementation shown, is in direct contact with) the semiconductor substrate  30 . A P+ substrate contact region  36  (rightmost item labeled “Sub” in  FIG. 8 ) is coupled with (and, in the implementation shown, is in direct contact with), the semiconductor substrate  30 . An N− channel region  42  is included in the semiconductor substrate and the source, gate, and drain regions are all coupled with the N− channel region. 
     The N+ source region  32  (labeled “Source” in  FIG. 8 ) is coupled with the N− channel region and, in the implementation shown, is in direct contact therewith. The gate region  34  (labeled “Gate” in  FIG. 8 ) is a P+ gate region and is coupled with (and in direct contact with) the N− channel region. The drain region (labeled “Drain” in  FIG. 8 ) includes a P+ drain region  38  (P+ anode) and an N+ drain region  40 . An electrical conductor  46  is shown covering all of the N+ drain region and a portion of the P+ drain region, thus the uncovered portion of the P+ drain region forms or becomes a resistive electrical ballast region (separation layer)  50 . A number of electrically insulative regions  44  separate the other regions at the surface of transistor  28  and may be formed of, by non-limiting example, SiO 2  or any other electrically insulative material. As described above, the electrical conductor  46  in implementations is an electrically conductive silicide, though in other implementations it may be formed of another electrically conductive material, such as a metal, and electrically conductive leads  48  may be coupled with the electrical conductor  46  as described above. 
     The configuration (P type, N type, etc.) of the substrate of transistor  28  may be configured utilizing any number of doping, diffusion, and/or annealing steps, or the like, with a silicon substrate, by non-limiting example. The various electrically insulative regions, drain regions, gate regions, source regions, substrate contact regions, cathode regions, and the like, each of which may have different electrical and/or other properties, may be formed by any number or combination of masking (photoresist), exposing, etching, washing, doping, implanting, diffusing, annealing, and/or other steps, using appropriate materials and dopants, and the like. 
     Although the various regions of transistor  28  are denoted by particular material types, i.e., a P type substrate, N+ source region, P+ gate region, P+ substrate contact region, P+ drain region (P+ anode), N+ drain region, N− channel region, silicide region, N+ cathode region, and so forth, other material types and combinations could be chosen by the practitioner of ordinary skill having similar or different electrical or other properties as desired (for instance beginning with an N type substrate and choosing the other material types accordingly). 
     As indicated to some extent above, the resistive electrical ballast regions are buffer regions or layers between the gate/source and the drain and help to increase the robustness of the device to damage from ESD. In implementations the resistive electrical ballast region  50  could be even greater, such as up to about 10 microns, in width. However, in experiments a 6 micron width for the resistive electrical ballast region (separation layer)  50  did not show notable improvement in ESD robustness over a 3 micron width. Simulation data indicated that the effect of a 1 micron width resistive electrical ballast region (separation layer)  50  was much less effective than a 3 micron width region, and that the protection from a 5 micron width region was similar to that of a 3 micron width region. Thus it appears that the protective benefits may be located in a range of widths of about 3-5 microns. 
     In various implementations, the transistor is an ultra-high voltage device and the depletion layer, at several hundred volts of operation, must extend about 100 microns in depth. In such circumstances it may be desirable to have a P type semiconductor substrate instead of an N type semiconductor substrate. An alternative may be to form a thick P epitaxial layer on an N doped substrate, but in such a case the overall thickness may need to be more than 100 microns and may make this option less desirable. 
     The configuration of transistor  28  shows an improved ESD robustness for an ultra high voltage (800 V) silicon controlled rectifier junction field-effect transistor (SCR-JFET). Although there have been laterally diffused metal oxide semiconductors (LDMOS) with a silicon controlled rectifier (SCR) structure that have exhibited acceptable ESD robustness, achieving ESD robustness in the ultra high voltage range (≥800 V) has remained a challenging issue. 
     Most of the ESD surge current flows not from the N+ drain region but from the P+ drain region (P+ anode of the SCR), thus the extension of the P+ drain region creates an effective resistive electrical ballast region (separation layer)  50  that increases the ESD robustness. The addition of the resistive electrical ballast region  50  does not greatly alter the size of the overall device. In a representative example the diameter of a reference device without the resistive electrical ballast region  50  was 410 microns, and the width of the resistive electrical ballast region  50  was 3 microns, so the overall diameter of the altered device was 416 microns. The area penalty for the addition of the resistive electrical ballast region  50  is negligible. 
     HBM robustness of an 800 V SCR-JFET transistor  28  with the resistive electrical ballast region  50  was measured and compared with a similar 800 V SCR-JFET without the resistive electrical ballast region  50 . Both transistors had a same drain width of 1900 microns. HBM robustness was improved from about 2000 V to 6000 V by implementing the resistive electrical ballast region  50   
     The transistors described herein may be used in a variety of product such as, by non-limiting example: off-line pulse width modulation (PWM) controllers for consumer and computing power supplies; 700 V startup product families such as adapters, flat TVs, low power, LED lighting; HB drivers, as a power transistor, and the like. 
     Referring now to  FIG. 9 , in implementations an electrostatic discharge (ESD) robust semiconductor transistor (transistor)  54  has a structure similar to transistor  28  except without the N+ cathode region  52 . The other elements are similar, including the resistive electrical ballast region (separation layer), similar to that of transistor  28 , and in implementations this resistive electrical ballast region (separation layer) may be 3 microns or more in width, similar as has been discussed herein relative to transistor  28 . Transistor  54  is thus in some ways functionally and structurally similar to transistor  28 . 
     In transistor  54 , a PNPN path exists from the P+ drain region (P+ anode)  12 , through the N− channel region  16 , through the P type substrate  4  or the P+ gate region  8 , then via the N− channel region  16  to the N+ source region  6  which acts as an N+ cathode, and therefore transistor  54  forms a silicon controlled rectifier (SCR) structure. Transistor  28  also has a PNPN path similar to transistor  54  from P+ drain region (P+ anode)  38 , through the N− channel region  42 , through the P type substrate  30  or the P+ gate region  34 , then via N− channel region  42  to the N+ source region  32  which acts as an N+ cathode, and therefore transistor  28  forms a silicon controlled rectifier (SCR) structure. Transistor  28  forms another PNPN path from the P+ drain region (P+ anode)  38 , through the N− channel region  42 , through the P type substrate  30 , and through the N+ cathode region  52 . Thus there are two current paths that allow the SCR structure in transistor  28 . The N+ cathode region  52  allows the N+ source region  32  to not be grounded, which in implementations may result in more flexible circuit design. 
     In implementations, most of the current may go through the P type substrate but in other implementations the P+ gate may form a portion of a PNPN path as described above. 
       FIG. 10  shows a representative example of an ESD robust semiconductor transistor (transistor)  58  formed using a laterally-diffused metal-oxide semiconductor (LDMOS) process/structure. The transistor  58  includes a semiconductor substrate  60  which in implementations is a P type substrate, though in other implementations it could be an N type substrate. An N well region  72  and a P well region  74  are included, and a gate region  64  couples with both of the well regions through an oxide  88 , forming the metal-oxide semiconductor (MOS) structure. In implementations the gate region is an N+ gate region, though in other implementations other configurations could be used for the gate region. 
     The N well region and P well region are next to one another and a source region  62  resides above (and is in direct contact with) the P well region. In implementations the source region is an N+ source region. A P+ substrate contact region  66  also resides above (and is in direct contact with) the P well region. The P+ substrate contact region  66  is coupled with the P type substrate through the P well region and the P well region fully separates the P+ substrate contact region from the semiconductor substrate. 
     The drain region of the transistor  58  includes a P+ drain region (P+ anode)  68  and an N+ drain region  70 . A number of electrically insulative regions  76  are located at the upper surface of the device and between the various other elements and contacts, and may include SiO 2  or some other electrically insulative material. A silicide  78  covers all of the N+ drain region and a portion of the P+ drain region, and may be formed of any electrically conductive silicide material. A resistive electrical ballast region (separation layer)  80  is thus formed, and operates similarly to others described herein by increasing the ESD robustness of the transistor. In implementations the resistive electrical ballast region (separation layer)  80  may have a width ranging from 3-10 microns. In implementations the resistive electrical ballast region (separation layer)  80  has a width of at least 3 microns. The resistive electrical ballast region forms a separation layer between the silicide and an electrically insulative region  76  of the transistor. Transistor  58  is an LDMOS transistor. 
       FIG. 11  shows a representative example of an ESD robust semiconductor transistor (transistor)  82  formed using an LDMOS process/structure and is similar to transistor  58  except that the N well region  84  extends below the P well region  86  and therefore fully separates the P well region from the P type substrate, thus forming a PNP structure vertically below the P+ substrate contact region (P well region, N well region, and P type substrate stacked vertically). A silicide  78  covers all of the N+ drain region and a portion of the P+ drain region, and may be formed of any electrically conductive silicide material. A resistive electrical ballast region (separation layer)  80  is formed, and operates similarly to others described herein by increasing the ESD robustness of the transistor. In implementations the resistive electrical ballast region (separation layer)  80  may have a width ranging from 3-10 microns. In implementations the resistive electrical ballast region (separation layer)  80  has a width of at least 3 microns. The resistive electrical ballast region forms a separation layer between the silicide and an electrically insulative region  76  of the transistor. Transistor  82  is an LDMOS transistor. 
     As used herein, “conductivity type” refers to either P type (including P, P+, P−) and/or N type (including N, N+, N−) conductivity. 
     As disclosed above, and referring again to  FIG. 9 , in implementations an ESD robust semiconductor transistor (transistor)  54  includes a semiconductor substrate  4  of a first conductivity type, a substrate contact region  10  of the first conductivity type coupled with the semiconductor substrate, a source region  6  of a second conductivity type coupled with the semiconductor substrate, a channel region  16  of the second conductivity type, a gate region  8  of the first conductivity type, a drain region having a first drain region  12  of the first conductivity type and a second drain region  14  of the second conductivity type, and an electrical conductor  56  coupled over the second drain region and a portion of the first drain region, wherein a portion of the first drain region is not covered by the electrical conductor and becomes a resistive electrical ballast region configured to protect the transistor from ESD induced voltage pulses, and wherein the transistor forms a silicon controlled rectifier junction field effect transistor (SCR JFET). 
     Referring still to  FIG. 9 , in implementations the first conductivity type is P type conductivity and the second conductivity type is N type conductivity, though these polarities may be reversed in other implementations. In implementations the channel region  16  is an N− channel region, and the transistor is an N− channel SCR JFET. In implementations the semiconductor substrate  4  is a P type substrate, the substrate contact region  10  is a P+ substrate contact region, the source region  6  is an N+ source region, the gate region  8  is a P+ gate region, the first drain region  12  is a P+ drain region, and the second drain region is an N+ drain region. The electrical conductor  56  may include, or may be fully formed of, a silicide. The resistive electrical ballast region may have a width of at least 3 microns and may form a separation layer between the electrical conductor and an electrically insulative region  18 . The transistor may form a stadium shape. 
     Referring to  FIG. 8 , in implementations an ESD robust semiconductor transistor (transistor)  28  includes a semiconductor substrate  30  of a first conductivity type, a first substrate contact region  36  of the first conductivity type coupled with the semiconductor substrate, a source region  32  of a second conductivity type coupled with the semiconductor substrate, a channel region  42  of the second conductivity type, a gate region  34  of the first conductivity type, a drain region having a first drain region  38  of the first conductivity type and a second drain region  40  of the second conductivity type, a second substrate contact region  52  of the second conductivity type coupled with the semiconductor substrate, and an electrical conductor  46  coupled over the second drain region and a portion of the first drain region, wherein a portion of the first drain region not covered by the electrical conductor forms a resistive electrical ballast region  50  configured to protect the transistor from ESD induced voltage impulses, and wherein the transistor includes a silicon controlled rectifier junction field effect transistor (SCR JFET). 
     Still referring to  FIG. 8 , in implementations the first conductivity type is P type conductivity and the second conductivity type is N type conductivity, though these polarities may be reversed in other implementations. In implementations the channel region includes an N− channel region, and the SCR JFET includes an N− channel SCR JFET. In implementations the semiconductor substrate includes a P type substrate, the first substrate contact region includes a P+ substrate contact region, the source region includes an N+ source region, the channel region includes an N− channel region, the gate region includes a P+ gate region, the first drain region includes a P+ drain region (P+ anode), the second drain region includes an N+ drain region, and the second substrate contact region includes an N+ substrate contact region (N+ cathode). In implementations the electrical conductor  46  includes, or is fully formed of, a silicide. The resistive electrical ballast region  50  may include a width of at least 3 microns and forms a separation layer between the electrical conductor and an electrically insulative region  44 . The transistor may have a stadium shape. 
     Referring to  FIGS. 10-11 , in implementations an EST robust semiconductor transistor (transistor) includes a semiconductor substrate  60  of a first conductivity type, a substrate contact region  66  of the first conductivity type coupled with the semiconductor substrate through a first well region  74 / 86  of the first conductivity type, the first well region separating the substrate contact region from the semiconductor substrate, a source region  62  of a second conductivity type coupled with the semiconductor substrate, a second well region  72 / 84  of the second conductivity type coupled with the semiconductor substrate, a drain region having a first drain region  68  of the first conductivity type and a second drain region  70  of the second conductivity type, a gate region  64 , and a silicide coupled over the second drain region and a portion of the first drain region, wherein a portion of the first drain region not covered by the silicide forms a resistive electrical ballast region  80  having a width of at least 3 microns and configured to protect the transistor from ESD induced voltage pulses, and wherein the transistor forms a silicon controlled rectifier field effect transistor (SCR FET). 
     Still referring to  FIGS. 10-11 , in implementations the SCR JFET could form a metal-semiconductor field effect transistor (MESFET), a metal-oxide semiconductor field effect transistor (MOSFET), a superjunction FET, and the like. In implementations the SCR FET forms a laterally diffused metal oxide semiconductor (SCR LDMOS) transistor. In implementations the first conductivity type is P type conductivity and the second conductivity type is N type conductivity, though these polarities may be reversed in other implementations. 
     In implementations the semiconductor substrate includes a P type substrate, the substrate contact region includes a P+ substrate contact region, the first well region includes a P well region, the second well region includes an N well region, the source region includes an N+ source region, the gate region includes an N+ gate region, the first drain region includes a P+ drain region, and the second drain region includes an N+ drain region. Referring to  FIG. 10 , in implementations the first well region  74  fully separates the substrate contact region  66  from the semiconductor substrate  60  and the first well region directly contacts the semiconductor substrate. Referring to  FIG. 11 , in implementations the second well region  84  fully separates the first well region  86  from the semiconductor substrate  60 . 
     Examples of conventional transistor designs may be found in the following references, each of which is entirely incorporated herein by reference: Fujiwara, S., Nakaya, K., Hirano, T., Okuda, T., Watanabe, Y., “Source engineering for ESD robust NLDMOS,” published at 33rd Electrical Overstress/Electrostatic Discharge Symposium (EOS/ESD), 11-16 Sept. 2011, Anaheim Calif., pg. 1-6; Pendharkar, S., Teggatz, R., Devore, J., Carpenter, J., Efland, T., Chin-Yu Tsai, “SCR-LDMOS: A novel LDMOS device with ESD robustness,” published at The 12th International Symposium on Power Semiconductor Devices and ICs, 2000, pg. 341-344; Jung-Ruey Tsai, Yuan-Min Lee, Min-Chin Tsai, Gene Sheu, Shao-Ming Yang, “Development of ESD robustness enhancement of a novel 800V LDMOS multiple RESURF with linear P-top rings,” published at TENCON 2011-2011 IEEE Region 10 Conference, pg. 760-763, 21-24 Nov. 2011; Chin-Yu Tsai, Taylor Efland, Sameer Pendharkar, Jozef Mitros, Alison Tessmer, Jeff Smith, John Erdeljac, Lou Hutter, “16-60V Rated LDMOS Show Advanced Performance in an 0.72 um Evolution BiCMOS Power Technology,” published in Technical Digest of International Electron Devices Meeting (IEDM) 1997 by IEEE, p. 367-370, disclosed at conference proceedings at least as early as 10 Dec. 1997 at Washington, DC, and; Jeffrey Smith, Alison Tessmer, Lily Springer, Praful Madhani, John Erdeljac, Jozef Mitros, Taylor Efland, Chin-Yu Tsai, Sameer Pendharkar, Louis Hutter, “A 0.7 um Linear BiCMOS/DMOS Technology for Mixed-Signal/Power Applications,” Published in Proceedings of the Bipolar/BiCMOS Circuits and Technology Meeting 1997, p. 155-157 by IEEE, disclosed at conference proceedings at least as early as 30 Sep. 1997 at Minneapolis, Minn. 
     In places where the description above refers to particular implementations of ESD robust transistors and related methods and implementing components, sub-components, methods and sub-methods, it should be readily apparent that a number of modifications may be made without departing from the spirit thereof and that these implementations, implementing components, sub-components, methods and sub-methods may be applied to other ESD robust transistors and related methods.