Power Semiconductor Devices Having Termination Structures and Methods of Manufacture

• US 20080135931A1
• Filed: 02/15/2008
• Published: 06/12/2008
• Est. Priority Date: 05/20/2003
• Status: Active Grant

• Current Assignee: Semiconductor Components Industries LLC (ON Semiconductor Corporation)
• Original Assignee: Adam Selsley, Alan Elbanhawy, Ashok Challa, Babak S. Sanl, Becky Losee, Bruce D. Marchant, Chongman Yun, Christopher B. Kocon, Christopher L. Rexer, Dean E. Probst, Debra S. Woolsey, Gary M. Dolny, Gordon K. Madson, H.C. Jang, James J. Murphy, J.G. Lee, John Mytych, Joseph A. Yedinak, Jung Jy, Nathan L. Kraft, Peter H. Wilson, Qi Wang, Richard Stokes, Robert Herrick, Rodney S. Ridlay, Steven P. Sapp, Thomas E. Grebs
• Inventors: Herrick, Robert, Probst, Dean E., Murphy, James J., Losee, Becky, Elbanhawy, Alan, Wang, Qi, Wilson, Peter H., Yedinak, Joseph A., Stokes, Richard, Yun, Chongman, Marchant, Bruce D., Dolny, Gary M., Selsley, Adam, Sapp, Steven P., Kraft, Nathan L., Kocon, Christopher B., Grebs, Thomas E., Woolsey, Debra S., Madson, Gordon K., Ridlay, Rodney S., Lee, J.G., Mytych, John, Jang, H.C., Rexer, Christopher L., Jung, J.Y., Sanl, Babak S., Challa, Ashok
• Granted Patent: US 7,855,415 B2
• Time in Patent Office: Days
• US Class Current: 257/331
• CPC Class Codes: H01L 21/26586 characterised by the angle between the ion beam and the crystal planes or the main crystal surface
• CPC Class Codes: H01L 21/3065 Plasma etching; Reactive-ion etching
• CPC Class Codes: H01L 21/30655 comprising alternated and repeated etching and passivation steps, e.g. Bosch process
• CPC Class Codes: H01L 21/31116 by dry-etching
• CPC Class Codes: H01L 21/6835 using temporarily an auxiliary support
• CPC Class Codes: H01L 2221/6834 used to protect an active side of a device or wafer
• CPC Class Codes: H01L 2221/68363 used in a transfer process involving transfer directly from an origin substrate to a target substrate without use of an intermediate handle substrate
• CPC Class Codes: H01L 2224/16 of an individual bump connector
• CPC Class Codes: H01L 23/4952 the additional leads being a bump or a wire
• CPC Class Codes: H01L 23/49816 Spherical bumps on the substrate for external connection, e.g. ball grid arrays [BGA]
• CPC Class Codes: H01L 27/0629 in combination with diodes, or resistors, or capacitors
• CPC Class Codes: H01L 29/0623 Buried supplementary region, e.g. buried guard ring multi-RESURF H01L29/0634
• CPC Class Codes: H01L 29/0634 Multiple reduced surface field (multi-RESURF) structures, e.g. double RESURF, charge compensation, cool, superjunction (SJ), 3D-RESURF, composite buffer (CB) structures
• CPC Class Codes: H01L 29/0653 adjoining the input or output region of a field-effect device, e.g. the source or drain region
• CPC Class Codes: H01L 29/0661 specially adapted for altering the breakdown voltage by removing semiconductor material at, or in the neighbourhood of, a reverse biased junction, e.g. by bevelling, moat etching, depletion etching
• CPC Class Codes: H01L 29/0696 of cellular field-effect devices, e.g. multicellular DMOS transistors or IGBTs
• CPC Class Codes: H01L 29/1095 Body region, i.e. base region, of DMOS transistors or IGBTs cell layout H01L29/0696
• CPC Class Codes: H01L 29/165 in different semiconductor regions , e.g. heterojunctions
• CPC Class Codes: H01L 29/402 Field plates
• CPC Class Codes: H01L 29/407 Recessed field plates, e.g. trench field plates, buried field plates
• CPC Class Codes: H01L 29/41766 : with at least part of the source or drain electrode having contact below the semiconductor surface, e.g. the source or drain electrode formed at least partially in a groove or with inclusions of conductor inside the semiconductor H01L29/41733 - H01L29/41758 take precedence
• CPC Class Codes: H01L 29/4236 : within a trench, e.g. trench gate electrode, groove gate electrode
• CPC Class Codes: H01L 29/42368 : the thickness being non-uniform
• CPC Class Codes: H01L 29/4238 : characterised by the surface lay-out
• CPC Class Codes: H01L 29/4933 : with a silicide layer contacting the silicon layer, e.g. Polycide gate with a barrier layer between the silicide and silicon layers H01L29/4941
• CPC Class Codes: H01L 29/495 : the conductor material next to the insulator being a simple metal, e.g. W, Mo H01L29/4908, H01L29/4983 take precedence
• CPC Class Codes: H01L 29/66348 : with a recessed gate
• CPC Class Codes: H01L 29/66734 : with a step of recessing the gate electrode, e.g. to form a trench gate electrode
• CPC Class Codes: H01L 29/7396 : with a non planar surface, e.g. with a non planar gate or with a trench or recess or pillar in the surface of the emitter, base or collector region for improving current density or short circuiting the emitter and base regions H01L29/7398 takes precedence
• CPC Class Codes: H01L 29/7802 : Vertical DMOS transistors, i.e. VDMOS transistors
• CPC Class Codes: H01L 29/7804 : the other device being a pn-junction diode
• CPC Class Codes: H01L 29/7805 : in antiparallel, e.g. freewheel diode
• CPC Class Codes: H01L 29/7806 : the other device being a Schottky barrier diode
• CPC Class Codes: H01L 29/7811 : with an edge termination structure guard regions per se H01L29/0619; field plates per se H01L29/402
• CPC Class Codes: H01L 29/7813 : with trench gate electrode, e.g. UMOS transistors trench gate electrodes per se H01L29/4236
• CPC Class Codes: H01L 29/7815 : with voltage or current sensing structure, e.g. emulator section, overcurrent sensing cell
• CPC Class Codes: H01L 29/7828 : without inversion channel, e.g. vertical ACCUFETs, normally-on vertical MISFETs
• CPC Class Codes: H01L 29/7831 : with multiple gate structure FinFETs or MuGFETs H01L29/7855, thin film transistors H01L29/78645
• CPC Class Codes: H01L 2924/00 : Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
• CPC Class Codes: H01L 2924/00014 : the subject-matter covered by the group, the symbol of which is combined with the symbol of this group, being disclosed without further technical details
• CPC Class Codes: H01L 2924/01012 : Magnesium [Mg]
• CPC Class Codes: H01L 2924/01019 : Potassium [K]
• CPC Class Codes: H01L 2924/01078 : Platinum [Pt]
• CPC Class Codes: H01L 2924/10253 : Silicon [Si]
• CPC Class Codes: H01L 2924/12032 : Schottky diode
• CPC Class Codes: H01L 2924/1301 : Thyristor
• CPC Class Codes: H01L 2924/13034 : Silicon Controlled Rectifier [SCR]
• CPC Class Codes: H01L 2924/1305 : Bipolar Junction Transistor [BJT]
• CPC Class Codes: H01L 2924/13055 : Insulated gate bipolar transistor [IGBT]
• CPC Class Codes: H01L 2924/13091 : Metal-Oxide-Semiconductor Field-Effect Transistor [MOSFET]
• CPC Class Codes: H01L 2924/15311 : being a ball array, e.g. BGA
• CPC Class Codes: H01L 2924/1532 : the connection portion being formed on the die mounting surface of the substrate
• CPC Class Codes: H01L 2924/19041 : being a capacitor
• CPC Class Codes: H01L 2924/30105 : Capacitance
• CPC Class Codes: H01L 2924/3011 : Impedance
• CPC Class Codes: H01L 2924/3025 : Electromagnetic shielding
• CPC Class Codes: H02M 3/00 : Conversion of dc power input into dc power output
• CPC Class Codes: H02M 3/33592 : having a synchronous rectifier circuit or a synchronous freewheeling circuit at the secondary side of an isolation transformer
• CPC Class Codes: H02M 7/48 : using discharge tubes with control electrode or semiconductor devices with control electrode
• CPC Class Codes: Y02B 70/10 : Technologies improving the efficiency by using switched-mode power supplies [SMPS], i.e. efficient power electronics conversion e.g. power factor correction or reduction of losses in power supplies or efficient standby modes

Abstract

A semiconductor power device includes a drift region of a first conductivity type, a well region extending above the drift region and having a second conductivity type opposite the first conductivity type, an active trench extending through the well region and into the drift region, source regions having the first conductivity type formed in the well region adjacent the active trench, and a first termination trench extending below the well region and disposed at an outer edge of an active region of the device. The sidewalls and bottom of the active trench are lined with dielectric material, and substantially filled with a first conductive layer forming an upper electrode and a second conductive layer forming a lower electrode, the upper electrode being disposed above the lower electrode and separated therefrom by inter-electrode dielectric material. The first termination trench can be lined with a layer of dielectric material that is thicker than the dielectric material lining the sidewalls of the active trench, and is substantially filled with conductive material.

Claims

1-156. -156. (canceled)

157. A semiconductor device comprising:

a drift region of a first conductivity type;

a well region extending above the drift region and having a second conductivity type opposite the first conductivity type;

an active trench extending through the well region and into the drift region, the active trench having its sidewalls and bottom lined with dielectric material, and substantially filled with a first conductive layer forming an upper electrode and a second conductive layer forming a lower electrode, the upper electrode being disposed above the lower electrode and separated therefrom by inter-electrode dielectric material;

source regions having the first conductivity type formed in the well region adjacent the active trench; and

a first termination trench extending below the well region and disposed at an outer edge of an active region of the device.

158. The semiconductor device of claim 157 wherein the first termination trench is lined with a layer of dielectric material that is thicker than the dielectric material lining the sidewalls of the active trench, and is substantially filled with conductive material.

159. The semiconductor device of claim 158 wherein the conductive material inside the first termination trench electrically couples to source metal.

160. The semiconductor device of claim 158 wherein the conductive material inside the first termination trench is buried under dielectric material in a lower portion of the termination trench.

161. The semiconductor device of claim 157 wherein the first termination trench is substantially filled with dielectric material.

162. The semiconductor device of claim 157 wherein width of a mesa formed between the first termination trench and an adjacent active trench is different than the width of a mesa formed between two active trenches.

163. The semiconductor device of claim 157 wherein the first termination trench surrounds an active area of the device in the shape of a ring.

164. The semiconductor device of claim 163 further comprising a second termination trench that surrounds the active area of the device outside the first termination trench.

165. The semiconductor device of claim 164 wherein a distance S1 between the first and second termination trenches is approximately twice a distance S2 between the first termination trench and an end of the active trench.

166. A termination structure at an outer edge of a semiconductor device, the termination structure comprising a plurality of concentric rings of pillars of first conductivity type formed inside a termination region of second conductivity type opposite the first conductivity type, and surrounding an active area of the device, wherein each pillar separately connects to a conductive field plate.

167. The termination structure of claim 166 wherein a large field plate made of conductive material covers and is dielectrically isolated from a subset of the plurality of pillars, and a separate conductive field plate connects to a remaining one of the plurality of pillars.

168. The termination structure of claim 167 wherein the large field plate is coupled to ground.

169. The termination structure of claim 166 wherein a subset of the pillars are not covered by any conductive field plate.

170. The termination structure of claim 166 wherein a center-to-center spacing between the plurality of pillars varies with distance from edge of the active area.

171. The termination structure of claim 170 wherein the center-to-center spacing between the plurality of pillars increases with distance from edge of the active area.

172. The termination structure of claim 166 wherein a width of each pillar varies with distance from edge of the active area.

173. The termination structure of claim 172 wherein a width of each pillar decreases with distance from edge of the active area.

174. The termination structure of claim 166 wherein a width of the plurality of pillars in the termination structure remains substantially the same whereas a width of opposite polarity pillars under well regions inside the active area decrease with distance from the well region.

175-235. -235. (canceled)

236. A method of forming a semiconductor device comprising:

forming a drift region of a first conductivity type;

forming a well region extending above the drift region, the well region having a second conductivity type opposite the first conductivity type;

forming an active trench extending through the well region and into the drift region;

lining the active trench sidewalls and bottom with a dielectric material;

forming a first conductive layer over the dielectric material on the bottom on the trench;

depositing an inter-electrode dielectric material over the first conductive layer in the active trench;

forming a second conductive layer over the inter-electrode dielectric material;

forming source regions in the well region adjacent the active trench, the source regions having the first conductivity type; and

forming a first termination trench extending below the well region and disposed at an outer edge of an active region of the device.

237. The method of claim 236 further comprising:

lining the first termination trench with a layer of dielectric material that is thicker than the dielectric material lining the sidewalls of the active trench; and

substantially filling the lined first termination trench with a conductive material.