JP2011082548A - High breakdown voltage semiconductor switching element and switching power supply using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a high breakdown voltage semiconductor switching element capable of reducing loss over the whole range from a light load to a heavy load, and a switching power supply using the same. <P>SOLUTION: An N-type region 202 is formed at a surface part of a semiconductor substrate 201. A P-type base region is formed in the semiconductor substrate 201 contiguously with the N-type region 202. In the base region, an N-type emitter/source region 206 is formed separately from the N-type region 202. A gate electrode 210 is formed so as to cover the base region between the emitter/source region 206 and N-type region 202. In the N-type region 202, an N-type drain region 213 and a P-type collector region 203 are formed separately from the base region. Further, there are provided an electrode electrically connected to the collector region 203 and drain region 213, and an electrode electrically connected to the base region and emitter/source region 206. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a switching power supply device, and more particularly to a high voltage semiconductor switching element that is used in a switching power supply device and repeatedly opens and closes a main current.

  In recent years, from the viewpoint of global warming prevention measures, reduction of standby power for home appliances and the like has attracted attention, and a switching power supply device with lower power consumption during standby is strongly demanded.

  A conventional switching power supply device will be described below.

  FIG. 13 shows an example of a circuit configuration of a conventional switching power supply device. As shown in FIG. 13, the conventional switching power supply device includes a primary side rectifying / smoothing circuit 111, a main body circuit 112, a transformer 104, and a secondary side rectifying / smoothing circuit 121.

  Specifically, the AC voltage input between the input terminals 116 and 117 of the primary side rectifying and smoothing circuit 111 is rectified and smoothed by the primary side rectifying and smoothing circuit 111 and supplied to the main circuit 112 as an input DC voltage. Here, the primary side rectifying / smoothing circuit 111 includes a diode bridge 131 and an input capacitor 132, and a voltage that has been full-wave rectified by the diode bridge 131 is smoothed by the input capacitor 132 and supplied to the main circuit 112. ing.

  In the main circuit 112, a semiconductor switching element 113 and a voltage control circuit 114 are provided. The semiconductor switching element 113 and the voltage control circuit 114 can be integrated on one chip. A primary winding 141 is provided in the transformer 104, and the primary winding 141 and the semiconductor switching element 113 are connected in series, and the input DC voltage from the primary side rectifying and smoothing circuit 111 is connected to the series connection circuit. Have been supplied.

  The control terminal of the semiconductor switching element 113 is connected to the voltage control circuit 114, and the semiconductor switching element 113 is controlled to be turned on and off by a gate signal output from the voltage control circuit 114.

  In the transformer 104, a secondary winding 142 magnetically coupled to the primary winding 141 and an auxiliary winding 143 magnetically coupled to the primary winding 141 and the secondary winding 142 are provided. When the semiconductor switching element 113 performs a switching operation and a current flows intermittently in the primary winding 141, a voltage is induced in the secondary winding 142 and the auxiliary winding 143.

  The secondary-side rectifying / smoothing circuit 121 rectifies and smoothes the voltage induced in the secondary winding 142 to generate a DC output voltage and outputs it from the output terminals 126 and 127. Specifically, the secondary side rectifying / smoothing circuit 121 includes a diode 122, a choke coil 123, and first and second output capacitors 124 and 125. The choke coil 123 and the first and second output capacitors 124 and 125 are π-type connected, and the voltage induced in the secondary winding 142 is half-wave rectified by the diode 122 and the choke coil 123 Smoothed by the first and second output capacitors 124 and 125.

  The voltage generated at both ends of the auxiliary winding 143 is input to the control terminal of the semiconductor switching element 113 via the voltage control circuit 114. That is, the switching power supply device shown in FIG. 13 is a ringing choke converter (RCC) system, and the semiconductor switching element 113 performs a self-excited switching operation by the voltage generated in the auxiliary winding 143.

  The voltage between the output terminals 126 and 127 is fed back to the voltage control circuit 114 via the photocoupler 129. For example, when the voltage between the output terminals 126 and 127 decreases, the voltage control circuit 114 forcibly increases the conduction period of the semiconductor switching element 113, and conversely, the voltage between the output terminals 126 and 127 increases. In this case, the voltage control circuit 114 forcibly shortens the conduction period of the switching element 113. As a result, the voltage appearing at the output terminals 126 and 127 is maintained at a constant value.

  Inside the voltage control circuit 114, an auxiliary DC voltage is generated using the voltage induced in the auxiliary winding 143. Therefore, the voltage control circuit 114 does not support the auxiliary power supply except when the switching power supply is started. It operates with a direct current voltage.

  Note that when the switching power supply device is started, that is, when an AC voltage is applied between the input terminals 116 and 117, the semiconductor switching element 113 does not perform the switching operation, so there is no voltage induction in the auxiliary winding 143. The voltage control circuit 114 is in a no-power state. Therefore, in order to start the switching to the semiconductor switching element 113, a low voltage suitable for starting the voltage control circuit 114 is supplied from the primary side rectifying and smoothing circuit 111 through the external resistor 151 (high withstand voltage, high power). .

  In the switching power supply as described above, the loss mainly occurs in the semiconductor switching element 113. The switching element 113 is usually a MOSFET (Metal Oxide Semiconductor Field-Effect Transistor). In general, a bipolar transistor has a large switching loss when switching from a conductive state to a cut-off state, but a MOSFET has a small switching loss because of a high switching speed. On the other hand, unlike a bipolar transistor, a MOSFET has a large conduction resistance, so that conduction loss cannot be ignored. Therefore, when a large current flows through the MOSFET, the loss increases.

  In recent years, in the technical field of switching power supplies, bipolar IGBTs (Insulated Gate Bipolar Transistors) that inject minority carriers into the drift layer have attracted attention for unipolar MOSFETs. In the conventional switching power supply device shown in FIG. 13, when an IGBT is used for the switching element 113, conductivity modulation occurs as in the case of the bipolar transistor, so that the conduction resistance is reduced, but since minority carriers are used, the switching speed is increased. Slowing increases switching loss.

  By the way, in the RCC switching power supply as described above, when the load connected to the output terminals 126 and 127 is heavy, the switching frequency of the switching element 113 is lowered and the conduction period of the switching element 113 is lengthened. As a result, a large current flows through the primary winding 141, whereby the voltage between the output terminals 126 and 127 is maintained at a constant value. Conversely, at the time of a light load such as the standby mode, the switching frequency of the switching element 113 is increased and the conduction period is shortened. As a result, the current flowing through the primary winding 141 is reduced, thereby reducing the current between the output terminals 126 and 127. The voltage is maintained at a constant value.

  Accordingly, when both the switching loss and the conduction loss are viewed comprehensively, in the case of a heavy load, since the low frequency and the large current are obtained, the MOSFET becomes disadvantageous and the IGBT becomes advantageous. On the other hand, when the load is light as in the standby mode, the high frequency and low current result, so that the MOSFET becomes advantageous and the IGBT becomes disadvantageous.

  FIG. 14 is a diagram showing the results of comparing the relationship between load and loss when MOSFETs (horizontal type, drift region is a RESURF structure) and IGBTs (horizontal type) are used as switching power supplies, respectively. As shown in FIG. 14, the loss of the IGBT is large because the switching frequency is high on the low output (light load) side, and the loss of the MOSFET is low because the switching frequency is low on the high output (heavy load) side. It is getting bigger.

JP-A-7-153951 JP 2002-345242 A

  As described above, when a MOSFET is used as a switching element, conduction loss at a heavy load increases. On the other hand, when an IGBT is used as a switching element, the switching loss at standby or light load increases. It has been difficult for conventional semiconductor switching elements to reduce the loss over the entire area from the load to the heavy load.

  In view of the above, an object of the present invention is to provide a high voltage semiconductor switching element capable of reducing loss over the entire region from a light load to a heavy load, and a switching power supply device using the same.

  In order to achieve the above object, that is, in order to reduce loss over the entire range from light load to heavy load, the inventors of the present application have considered using two types of MOSFET and IGBT in one switching power supply. I tried.

  Incidentally, Patent Document 1 proposes a configuration in which a vertical IGBT and a vertical power MOSFET coexist in one chip of the switching element. However, in this configuration, the current capability of the vertical power MOSFET is too small with respect to the driving capability of the vertical IGBT, and as a result, it is practically difficult to drive the power MOSFET at a light load. Further, in this configuration, since a step must be formed on the back surface of the semiconductor substrate, the manufacturing process is difficult.

  Patent Document 2 proposes a configuration using a Schottky junction type IGBT as a switching element. However, in this Schottky junction type IGBT, the loss at light load is larger than that of the power MOSFET, and the loss at heavy load is also larger than that of the conventional IGBT. It cannot be said that it will make progress.

  Furthermore, since both switching elements of Patent Documents 1 and 2 have a vertical structure, for example, when the switching elements having these vertical structures are used as the semiconductor switching element 113 of the conventional switching power supply device shown in FIG. However, there is a problem that it is difficult to make the voltage control circuit 114 and the semiconductor switching element 113 into one chip.

  Based on the above knowledge, the inventors of the present application can use two types of MOSFETs and IGBTs as a single element as described below, and can achieve a one-chip control circuit and the like. It came to invent the semiconductor switching element and the switching power supply device using the same.

  That is, the high breakdown voltage semiconductor switching element according to the present invention is formed so as to be adjacent to the RESURF region in the semiconductor substrate, and the RESURF region of the second conductivity type formed in the surface portion of the first conductivity type semiconductor substrate. A first conductivity type base region formed; a second conductivity type emitter / source region formed in the base region spaced apart from the RESURF region; and the base region from above the emitter / source region. And at least the gate insulating film formed on the RESURF region, a gate electrode formed on the gate insulating film, and a drain of the second conductivity type formed in the RESURF region so as to be separated from the base region. A collector region of a first conductivity type formed in the RESURF region and spaced apart from the base region; and a collector region formed on the semiconductor substrate and A collector / drain electrode electrically connected to both the region and the drain region, and an emitter / source electrode formed on the semiconductor substrate and electrically connected to both the base region and the emitter / source region And.

  According to the high voltage semiconductor switching element of the present invention, the MOSFET can be operated when the collector current flowing through the element is relatively small, and the IGBT operation can be performed when the collector current becomes large. And IGBT can be used properly. Therefore, it is possible to operate a MOSFET at the time of standby or light load, and also to perform an IGBT operation at heavy load, thereby realizing a high voltage semiconductor switching element capable of reducing loss over the entire region from light load to heavy load. be able to.

  In addition, according to the high breakdown voltage semiconductor switching element of the present invention, the extended drain region (for example, the region corresponding to the N-type RESURF region 202 of the first embodiment and mainly holding the breakdown voltage) has a RESURF structure. The resistance during MOSFET operation can be lowered by the concentration of the RESURF layer. Therefore, a larger collector (drain) current can be passed in the MOSFET operation as compared with the conventional lateral element.

  The high breakdown voltage semiconductor switching element according to the present invention is a lateral element in which a collector electrode (collector / drain electrode) and an emitter electrode (emitter / source electrode) are provided on the same main surface of the substrate. Both circuits and the like can be made into one chip.

  In the high breakdown voltage semiconductor switching element of the present invention, the collector region and the drain region are each composed of a plurality of separated parts, and in the direction perpendicular to the direction from the collector region to the emitter / source region, It is preferable that each part of the collector region and each part of the drain region are arranged so as to alternately contact each other.

  In this case, for example, the MOSFET operation is switched to the IGBT operation as compared with the case where each portion of the collector region and each portion of the drain region are arranged along the direction from the collector region to the emitter / source region. Since it becomes difficult to change, a larger collector (drain) current can flow in the MOSFET operation. Further, the collector voltage Vch when switching from the MOSFET operation to the IGBT operation can be changed by changing the length of each part of the collector region.

  In this case, if the length of each part of the collector region in the direction perpendicular to the direction from the collector region to the emitter / source region is 48 μm or less, the length of each part of the collector region is less than 48 μm. Since the fall time (tf) can be shortened compared with the case where it sets too large, switching loss can be reduced. Further, the collector voltage Vch at the time of switching from the MOSFET operation to the IGBT operation can be increased as compared with the case where the length of each part of the collector region is larger than 48 μm. MOSFET operation can be performed.

  Also, in this case, the arrangement of each part of the collector region and each part of the drain region is terminated by a terminal portion that is a part of the drain region, and the resurf region has the base region Another drain region of the second conductivity type is formed separately, and another drain electrode electrically connected to the other drain region is formed on the semiconductor substrate. The drain region and the end portion of the drain region are electrically connected via the RESURF region, and the region of the RESURF region located between the other drain region and the end portion of the drain region is connected. At least a part of the drain region is narrower than the other part, so that when a voltage higher than a predetermined value is applied to the collector / drain electrode, the drain region ends. The current path to the other drain region is pinched off by the field effect from the preferred. In this way, even when a high voltage is applied to the collector electrode (collector / drain electrode), the voltage appearing on the other drain electrode can be pinched off (lowered) by the depletion layer extending from the semiconductor substrate to the RESURF region. . Therefore, by pinching off the voltage of the other drain electrode to, for example, about 10 V, it becomes possible to connect the other drain electrode to the element of the low voltage circuit and supply power to the element.

  In the high breakdown voltage semiconductor switching element of the present invention, it is preferable that a second conductivity type buffer layer having an impurity concentration higher than that of the RESURF region is provided between the collector region and the RESURF region.

  In this way, the efficiency of injection of holes from the collector region to the RESURF region is reduced, so that, for example, the fall time (tf) can be improved short.

  In the high breakdown voltage semiconductor switching element of the present invention, it is preferable that one or more first-conductivity-type semiconductor layers electrically connected to the base region are formed in the RESURF region.

  In this case, compared to the case where the first conductivity type semiconductor layer is not formed, since the impurity concentration of the RESURF region can be increased, the conduction resistance during MOSFET operation is reduced. As a result, since the collector (drain) current during MOSFET operation can be increased, more practical light load MOSFET operation is possible. In addition, at the time of turn-off in the IGBT operation, holes are pulled out from the first conductivity type semiconductor layer, so that the fall time (tf) can be shortened. Furthermore, since the impurity concentration in the RESURF region can be made higher, the lifetime of the holes in the RESURF region is shortened, whereby the fall time (tf) can be shortened.

  A switching power supply according to the present invention includes a semiconductor switching element to which an input DC voltage is applied, a voltage control circuit that controls opening and closing of the semiconductor switching element, and a primary electrically connected to an output terminal of the semiconductor switching element. Switching comprising a winding, a secondary winding magnetically coupled to the primary winding, and a rectifying and smoothing circuit for rectifying and smoothing a voltage induced in the secondary winding and supplying an output DC voltage to a load In the power supply device, the high-voltage semiconductor switching element according to the present invention is used as the semiconductor switching element.

  According to the switching power supply device of the present invention, since the high voltage semiconductor switching element of the present invention is used, the switching loss can be reduced by operating the MOSFET at a light load, and the IGBT operation is performed at a heavy load. Therefore, conduction loss can be reduced. Therefore, it is possible to realize a switching power supply that can reduce loss over the entire region from light load to heavy load.

  In the high breakdown voltage semiconductor switching element of the present invention used in the switching power supply device of the present invention, the collector region and the drain region are each composed of a plurality of separated parts, and are directed from the collector region to the emitter / source region. It is preferable that the portions of the collector region and the portions of the drain region are alternately arranged in a direction perpendicular to the direction. Here, in the high withstand voltage semiconductor switching element, the arrangement of each part of the collector region and each part of the drain region is terminated by a terminal part that is a part of the drain region, and the RESURF region An other drain region of the second conductivity type is formed in the interior of the semiconductor substrate so as to be separated from the base region, and another drain electrode electrically connected to the other drain region is formed on the semiconductor substrate. The other drain region and the end of the drain region are electrically connected via the RESURF region, and the other drain region of the RESURF region and the end of the drain region are formed. At least a part of the region located between the first and second electrodes is narrower than the other parts, so that a voltage higher than a predetermined value is applied to the collector / drain electrodes. In this case, it is preferable that the current path from the terminal end of the drain region to the other drain region is pinched off by the electric field effect, and the switching power supply device according to the present invention includes a starting circuit for starting the voltage control circuit. It is preferable that the other drain electrode of the high breakdown voltage semiconductor switching element and the starting circuit are electrically connected.

  In this way, since a low-voltage bias voltage for starting necessary for power-on can be generated inside the high-voltage semiconductor switching element, it is possible to use a high-voltage and high-power resistor for power supply, which has been conventionally required. A power supply device can be configured.

  The switching power supply of the present invention further includes an auxiliary winding magnetically coupled to both the primary winding and the secondary winding, and a voltage induced in the auxiliary winding is transmitted through the voltage control circuit. A ringing choke converter system applied to the gate terminal of the semiconductor switching element is preferably used.

  In this way, the switching frequency rises at light loads and decreases at heavy loads. Conversely, the high withstand voltage semiconductor switching element of the present invention that operates as a MOSFET at light loads and operates at IGBT at heavy loads is more effective. Can be used.

  ADVANTAGE OF THE INVENTION According to this invention, the high voltage | pressure-resistant semiconductor switching element which can reduce a loss over the whole region from a light load to a heavy load, and a switching power supply device using the same are realizable.

FIG. 1 is a cross-sectional view of a high voltage semiconductor switching element according to the first embodiment of the present invention. FIG. 2 is a plan view of the high breakdown voltage semiconductor switching element according to the first embodiment of the present invention. FIG. 3 is a sectional view of the high voltage semiconductor switching element according to the first embodiment of the present invention. FIG. 4 is a plan view showing a JFET portion of the high voltage semiconductor switching element according to the first embodiment of the present invention. FIG. 5 is a sectional view showing a JFET portion of the high voltage semiconductor switching element according to the first embodiment of the present invention. FIG. 6 is a diagram showing the correlation between the collector voltage and the collector current in the high breakdown voltage semiconductor switching element according to the first embodiment of the present invention. FIG. 7 is a diagram showing a correlation between the collector region length X, the fall time tf, and the collector voltage Vch switched to the IGBT operation in the high breakdown voltage semiconductor switching element according to the first embodiment of the present invention. FIG. 8 is a diagram showing an example of a circuit configuration of the switching power supply device according to the first embodiment of the present invention. FIG. 9 is a diagram showing the relationship between load and loss when the high voltage semiconductor switching element according to the first embodiment of the present invention is used in a switching power supply device. FIG. 10 is a cross-sectional view of a high voltage semiconductor switching element according to the second embodiment of the present invention. FIG. 11 is a cross-sectional view of a high voltage semiconductor switching element according to the third embodiment of the present invention. FIG. 12 is a plan view of a high voltage semiconductor switching element according to the fourth embodiment of the present invention. FIG. 13 is a diagram illustrating an example of a circuit configuration of a conventional switching power supply device. FIG. 14 is a diagram showing the results of comparing the relationship between load and loss when MOSFETs (horizontal type, drift region is a resurf structure) and IGBTs (horizontal type) are used as switching power supplies, respectively.

(First embodiment)
Hereinafter, a lateral high voltage semiconductor switching element according to a first embodiment of the present invention and a switching power supply device using the same will be described with reference to the drawings.

  1 to 3 are drawings showing an example of the configuration of the high voltage semiconductor switching element of the present embodiment, FIG. 2 is a plan view, and FIG. 1 is a sectional view taken along line AA ′ in FIG. FIG. 3 is a sectional view taken along line BB ′ in FIG. In FIG. 2, illustration of some components is omitted.

In the high breakdown voltage semiconductor switching element of the present embodiment shown in FIGS. 1 to 3, for example, a concentration of 1 × 10 ¹⁶ / cm ³ is formed on the surface of the P ⁻ type semiconductor substrate 201 having a concentration of about 1 × 10 ¹⁴ / cm ³ , for example. An N-type RESURF region 202 having a depth of about 7 μm is formed. Further, a p-type base region 204 having a concentration of, for example, about 1 × 10 ¹⁷ / cm ³ is formed in the semiconductor substrate 201 so as to be adjacent to the RESURF region 202. In the base region 204, a P ⁺ -type contact region 205 having a concentration of about 1 × 10 ¹⁹ / cm ³ and an N ⁺ -type emitter / source region 206 having a concentration of about 1 × 10 ²⁰ / cm ³ are separated from the RESURF region 202, for example. Are formed adjacent to each other. Here, the contact region 205 is disposed farther than the emitter / source region 206 when viewed from the RESURF region 202. A gate insulating film 209 is formed from the emitter / source region 206 over the base region 204 to at least the end portion of the RESURF region 202. A gate electrode 210 is formed on the gate insulating film 209.

Further, as shown in FIG. 1, a p ⁺ -type collector region 203 having a concentration of, for example, about 1 × 10 ¹⁹ / cm ³ is formed in the RESURF region 202 so as to be separated from the base region 204, as shown in FIG. Thus, an N ⁺ type drain region 213 having a concentration of about 1 × 10 ²⁰ / cm ³ is formed in the RESURF region 202 so as to be separated from the base region 204. Here, as shown in FIG. 2, the collector region 203 and the drain region 213 are each composed of a plurality of separated parts, and in a direction perpendicular to the direction from the collector region 203 to the emitter / source region 206. The portions of the collector region 203 and the portions of the drain region 213 are arranged so as to alternately contact each other.

  As shown in FIGS. 1 and 3, a collector / drain electrode 211 electrically connected to both the collector region 203 and the drain region 213 is formed on the semiconductor substrate 201, and the semiconductor substrate 201 is also formed. Above, an emitter / source electrode 212 is formed which is electrically connected to both the base region 204 and the emitter / source region 206. The emitter / source electrode 212 is electrically connected to the base region 204 through the contact region 205. Further, an interlayer film 208 is formed on the RESURF region 202 via a field insulating film 207, and the collector / drain electrode 211 and the emitter / source electrode 212 are respectively drawn on the interlayer film 208.

  In the high breakdown voltage semiconductor switching element of the present embodiment, a positive bias (hereinafter also referred to as a collector voltage) is applied between the collector / drain electrode 211 and the emitter / source electrode 212, and a positive voltage is applied to the gate electrode 210. When a voltage is applied, a current (hereinafter also referred to as a collector current) may flow from the drain region 213 to the emitter / source electrode 212 through the RESURF region 202, the base region 204 (portion serving as a channel region), and the emitter / source region 206. ) Starts to flow (MOSFET operation). By increasing the collector voltage, the collector current increases to some extent, and when the potential of the RESURF region 202 around the collector region 203 decreases by, for example, about 0.6 V compared to the collector region 203, holes are injected from the collector region 203 into the RESURF region 202. As a result, the MOSFET operation is shifted to the IGBT operation. At this time, the collector current flows from the collector region 203 to the emitter / source electrode 212 through the RESURF region 202 (or the semiconductor substrate 201), the base region 204, and the contact region 205. FIG. 6 shows the correlation between the collector voltage and the collector current in the high voltage semiconductor switching element of this embodiment.

  By the way, in the high breakdown voltage semiconductor switching element of the present embodiment, if the collector voltage for switching from the MOSFET operation to the IGBT operation is Vch, Vch is the collector region length X (from the collector region 203 to the emitter / source region 206 in FIG. 2). The length of each part of the collector region 203 in a direction perpendicular to the direction) can be changed. In FIG. 2, Y represents the drain region length (the length of each part of the drain region 213 in the direction perpendicular to the direction from the collector region 203 to the emitter / source region 206).

  FIG. 7 shows the collector region length X and the turn-off fall time (fall time tf: after turn-off, the collector current is reduced (changed) from 90% to 10% of the peak value in the high breakdown voltage semiconductor switching element of this embodiment. And the correlation with Vch. As shown in FIG. 7, when the collector region length X is shortened, the hole injection efficiency is decreased and tf is decreased. Further, when the collector region length X is shortened, a potential difference is less likely to occur between the collector region 203 and the surrounding RESURF region 202, and Vch increases. Conversely, when the collector region length X is increased, Vch decreases. Further, as the collector region length X is shortened, tf is reduced and the switching loss is reduced. In order to realize a practical light load MOSFET operation, Vch needs to be about 2 V or larger. Therefore, in the high breakdown voltage semiconductor switching element of this embodiment, it is desirable to design the collector region length X to 48 μm or less.

  According to the high-breakdown-voltage semiconductor switching element of the present embodiment described above, the MOSFET operation can be performed when the collector current flowing through the element is relatively small, and the IGBT operation can be performed when the collector current increases. Two types of MOSFET and IGBT can be used properly with one element. Therefore, it is possible to operate a MOSFET at the time of standby or light load, and also to perform an IGBT operation at heavy load, thereby realizing a high voltage semiconductor switching element capable of reducing loss over the entire region from light load to heavy load. be able to.

  Further, according to the high voltage semiconductor switching element of the present embodiment, since the N-type RESURF region 202 is used, the conduction resistance during MOSFET operation can be lowered by the RESURF region 202 having a high impurity concentration. For this reason, as shown in FIG. 6, a larger collector (drain) current can flow in the MOSFET operation as compared with the conventional lateral element.

  Further, according to the high breakdown voltage semiconductor switching element of this embodiment, the collector region 203 and the drain region 213 are each composed of a plurality of separated parts, and are perpendicular to the direction from the collector region 203 toward the emitter / source region 206. In the direction, each part of the collector region 203 and each part of the drain region 213 are arranged to contact each other alternately. Accordingly, since it is difficult to switch from the MOSFET operation to the IGBT operation, a larger collector (drain) current can flow in the MOSFET operation. Specifically, for example, when each part of the collector region 203 and each part of the drain region 213 are arranged along the direction from the collector region 203 toward the emitter / source region 206 unlike the present embodiment. In the MOSFET operation, the lower side of each part of the collector region 203 becomes a current path, and a voltage drop is likely to occur in the RESURF region 202 around the collector region 203. For this reason, hole injection is started from the collector region 203 to the RESURF region 202 before almost MOSFET operation, and the operation shifts to IGBT operation. Therefore, it is difficult to reduce loss over the entire region from light load to heavy load. Become. On the other hand, in the present embodiment, the above-described configuration of the collector region 203 and the drain region 213 makes it difficult to switch from the MOSFET operation to the IGBT operation, and a more practical light load MOSFET operation is possible.

  Further, since the high breakdown voltage semiconductor switching element of the present embodiment is a lateral element in which the collector / drain electrode 211 and the emitter / source electrode 212 are provided on the same main surface of the semiconductor substrate 201, both the gate signal control circuit and the like It can be made into one chip.

  In the high breakdown voltage semiconductor switching element of the present embodiment, the collector region 203 and the drain region 213 are each composed of a plurality of separated parts, and are perpendicular to the direction from the collector region 203 toward the emitter / source region 206. In FIG. 2, each part of the collector region 203 and each part of the drain region 213 are arranged so as to contact each other alternately. However, both or one of the collector region 203 and the drain region 213 may be a single region. Further, the arrangement of the collector region 203 and the drain region 213 is not particularly limited, except for the arrangement in which the switching from the MOSFET operation to the IGBT operation easily occurs as described above.

  FIG. 4 is a plan view showing a region not shown in the plan view of FIG. 2 in the high voltage semiconductor switching element of the present embodiment, and FIG. 5 is a cross-sectional view taken along line C-C ′ in FIG. 4.

As shown in FIGS. 4 and 5, the arrangement of each part of the collector region 203 and each part of the drain region 213 is an N ⁺ type having a concentration of about 1 × 10 ²⁰ / cm ^3, which is a part of the drain region 213. The drain region (termination drain region) 218 is terminated. An N ⁺ -type second drain region 219 having a concentration of about 1 × 10 ²⁰ / cm ³ is formed in the RESURF region 202 so as to be separated from the base region 204. A second drain electrode 220 electrically connected to the second drain region 219 is formed on the semiconductor substrate 201. The second drain electrode 220 is drawn on the interlayer film 208. The second drain region 219 and the termination drain region 218 are electrically connected via the RESURF region 202. Here, at least a part (hereinafter referred to as a JFET (Junction Field-Effect Transistor) part) 51 of a region located between the second drain region 219 and the termination drain region 218 in the RESURF region 202 is compared with other portions. Accordingly, when a voltage higher than a predetermined value is applied to the collector / drain electrode 211, the current path from the terminal drain region 218 to the second drain region 219 is pinched off by the electric field effect.

  In the high withstand voltage semiconductor switching element of the present embodiment, the voltage shown in the second drain electrode 220 is generated from the semiconductor substrate 201 even when a high voltage is applied to the collector / drain electrode 211 by the configuration shown in FIGS. It can be pinched off (lowered) by a depletion layer that extends into the RESURF region 202. Therefore, by pinching off the voltage of the second drain electrode 220 to about 10 V, for example, the second drain electrode 220 can be connected to the element of the low voltage circuit and power can be supplied to the element.

  FIG. 8 shows an example of a circuit configuration of a switching power supply device using the high voltage semiconductor switching element of the present embodiment shown in FIGS. As shown in FIG. 8, the switching power supply of the present embodiment is a ringing choke converter (RCC) type switching power supply, and includes a primary side rectifying and smoothing circuit 11, a body circuit 12, a transformer 4, and a secondary side rectifying and smoothing. Circuit 21.

  Specifically, the primary side rectifying and smoothing circuit 11 includes a diode bridge 31 and an input capacitor 32, and the input terminals 16 and 17 of the primary side rectifying and smoothing circuit 11 are connected to a commercial power source. The AC voltage applied between the input terminals 16 and 17 is full-wave rectified by the diode bridge 31 and then input to the input capacitor 32 to be smoothed, whereby the input DC voltage (the input DC voltage supplied to the main circuit 12). Voltage) is generated.

  In the main body circuit 12, the high voltage semiconductor switching element 13 and the voltage control circuit 14 of the above-described embodiment are provided. Here, the switching element 13, the voltage control circuit 14, the starting circuit 15 described later, the high breakdown voltage JFET portion 51, and the second drain electrode 220 extending from the JFET portion 51 to the starting circuit 15 are all integrated into one chip. It is integrated. A primary winding 41 is provided in the transformer 4. One end of the primary winding 41 is connected to the collector / drain electrode 211 of the switching element 13 of the present embodiment, and the other end of the primary winding 41 is connected. Are connected to the high potential side terminal of the input capacitor 32 of the primary side rectifying and smoothing circuit 11. Further, the emitter / source electrode 212 of the switching element 13 is connected to a terminal on the ground potential side of the input capacitor 32, whereby the input DC voltage output from the primary side rectifying / smoothing circuit 11 is connected to the primary winding 41. The switching element 13 is applied to a series connection circuit.

  In the transformer 4, a secondary winding 42 magnetically coupled to the primary winding 41 and an auxiliary winding 43 magnetically coupled to the primary winding 41 and the secondary winding 42 are provided. That is, the transformer 4 is configured such that a voltage is induced in the secondary winding 42 and the auxiliary winding 43 when a current flows intermittently in the primary winding 41.

  The voltage induced in the auxiliary winding 43 is input to the gate electrode 210 of the switching element 13 through the voltage control circuit 14. That is, the switching power supply device shown in FIG. 8 is configured such that self-excited oscillation is generated by the voltage induced in the auxiliary winding 43. When the switching element 13 performs a switching operation by self-excited oscillation, a current flows intermittently in the primary winding 41, and a voltage is induced in the secondary winding 42 and the auxiliary winding 43.

  In the secondary side rectifying and smoothing circuit 21, a rectifying diode 22, a choke coil 23, and first and second output capacitors 24 and 25 are provided. One end of the secondary winding 42 is connected to the anode terminal of the rectifier diode 22, and the cathode terminal of the rectifier diode 22 is connected to the high potential side terminal of the first output capacitor 24. The cathode terminal of the rectifier diode 22 is also connected to one end of the choke coil 23, and the other end of the choke coil 23 is connected to the output terminal 26 on the high potential side. The other end of the secondary winding 42 is connected to the output terminal 27 on the low potential side. The output terminal 27 on the low potential side includes the terminal on the low potential side of the first output capacitor 24 and the second output. An output terminal on the low potential side of the capacitor 25 is also connected. The polarity of the voltage induced in the secondary winding 42 is set to a polarity in which a positive voltage is applied to the anode terminal of the rectifier diode 22 when the switching element 13 changes from the conductive state to the cut-off state. When the rectifier diode 22 is forward biased, a current flows.

  The current flowing through the rectifier diode 22 charges the first output capacitor 24 and flows through the choke coil 23 to charge the second output capacitor 25. When a load is connected between the output terminals 26 and 27, the current flowing through the choke coil 23 is also supplied to the load. In this state, the voltage induced in the secondary winding 42 is smoothed by the first and second output capacitors 24 and 25 and the choke coil 23.

  When the switching element 13 changes from the cut-off state to the conductive state, a voltage that reversely biases the rectifier diode 22 is induced in the secondary winding 42, so that no current flows through the rectifier diode 22. In this state, a current is applied to the load connected between the output terminals 26 and 27 due to the electrostatic energy accumulated in the first and second output capacitors 24 and 25 and the magnetic energy accumulated in the choke coil 23. Supplied.

  The voltage between the output terminals 26 and 27 is fed back to the voltage control circuit 14 via the photocoupler 29. The voltage control circuit 14 controls the conduction period of the switching element 13 according to the magnitude of the voltage input from the photocoupler 29. Specifically, the voltage control circuit 14 increases the conduction period of the switching element 13 when the voltage between the output terminals 26 and 27 decreases, and conversely, when the voltage between the output terminals 26 and 27 increases. Forcibly shorten the conduction period of the switching element 13. As a result, the voltage appearing between the output terminals 26 and 27 is maintained at a constant value.

  In a state where a voltage is induced in the secondary winding 42, a voltage is also induced in the auxiliary winding 43. Inside the voltage control circuit 14, an auxiliary DC voltage is generated using the voltage induced in the auxiliary winding 43, and the voltage control circuit 14 supports the auxiliary DC voltage except when the switching power supply device is started. It operates with a direct current voltage.

  However, when the switching power supply device is started, since the switching element 13 is not performing a switching operation, no voltage is induced in the auxiliary winding 43 and the voltage control circuit 14 is in a state of no power supply. Here, when a voltage from an AC power supply is input to the input terminals 16 and 17, a part of the DC current generated in the primary side rectifying and smoothing circuit 11 and passing through the primary winding 41 in the transformer 4 is a high withstand voltage JFET portion. 51, the second drain electrode 220 and the starting circuit 15 are reached to reach the voltage control circuit 14, and the voltage control circuit 14 is started. Then, since the switching element 13 repeats opening and closing operations, a voltage is induced in the secondary winding 42 of the transformer 4 and the voltage control circuit 14 enters a steady operation state.

  As described above, when the high voltage semiconductor switching element of this embodiment is used in a switching power supply device, the high voltage JFET unit 51 can generate a starting low voltage required when the power is turned on. Therefore, a high withstand voltage and high power resistor (for example, the resistor 151 in FIG. 13) is not required. As a result, the wiring can be simplified, the cost can be reduced, and the power supply circuit can be downsized.

  Further, in the switching power supply device of the present embodiment, when the load connected between the output terminals 26 and 27 is heavy, the switching frequency of the switching element 13 is lowered and the conduction period of the switching element 13 is lengthened. When a large current flows through the primary winding 41, the voltage between the output terminals 26 and 27 is maintained at a constant value. Conversely, at a light load such as the standby mode, the switching frequency of the switching element 13 is increased and the conduction period of the switching element 13 is shortened, whereby the current flowing through the primary winding 41 is reduced, whereby the output terminal 26 and The voltage between 27 is maintained at a constant value.

  Here, in the switching power supply device of this embodiment, since the high voltage semiconductor switching device of this embodiment is used as the switching device 13, as shown in FIG. 9 (thick line), the switching loss is caused by the MOSFET operation at the time of light load. It is possible to reduce the conduction loss, and the conduction loss can be reduced by the IGBT operation at the time of heavy load. Therefore, the effect that the loss can be reduced over the entire region from the light load to the heavy load is obtained. In FIG. 9, for comparison, the losses of the MOSFET and IGBT shown in FIG. 14 are also shown.

  In addition, since the switching power supply of the present embodiment is an RCC type switching power supply, the switching frequency increases at light load and decreases at heavy load. On the other hand, the MOSFET operates at light load and operates at heavy load. The high-breakdown-voltage semiconductor switching element of the present embodiment that performs the IGBT operation can be used more effectively.

(Second Embodiment)
Hereinafter, a lateral high-breakdown-voltage semiconductor switching element according to a second embodiment of the present invention and a switching power supply device using the same will be described with reference to the drawings.

FIG. 10 is a cross-sectional view showing an example of the configuration of the high voltage semiconductor switching element of the present embodiment. As shown in FIG. 10, the high withstand voltage semiconductor switching element of the present embodiment is different from the first embodiment shown in FIG. 1 in that, for example, a concentration of 1 is used instead of the RESURF region 202 of the first embodiment. The p-type semiconductor layer 216 of about × 10 ¹⁶ / cm ³ has an N-type RESURF region 217 provided therein. Note that the p-type semiconductor layer 216 is formed immediately below the field insulating film 207 in the RESURF region 217 (surface portion of the RESURF region 217), and at a portion not shown, the base region 204 (that is, the emitter / source region 206). Electrically connected.

  According to the second embodiment, the following effects can be obtained in addition to the effects of the first embodiment. That is, when the reverse bias is applied, since the depletion layer is more easily spread in the resurf region 217, the resurf region 217 is formed with a higher impurity concentration than, for example, the resurf region 202 of the first embodiment shown in FIG. Can do. Thus, if the concentration of the RESURF region 217 can be formed higher, the conduction resistance during the MOSFET operation becomes smaller, so that a larger collector (drain) current can flow. That is, when the high voltage semiconductor switching element of the present embodiment is used as a switching power supply, a practical light load MOSFET operation is possible. In addition, since the holes are pulled out from the p-type semiconductor layer 216 at the turn-off in the IGBT operation, the fall time (tf) can be shortened. Furthermore, when the impurity concentration of the RESURF region 217 is high, the lifetime of the holes in the RESURF region 217 is shortened, thereby obtaining an effect that the fall time (tf) can be further shortened.

  In the present embodiment, one p-type semiconductor layer 216 is provided in the RESURF region 217, but a plurality of p-type semiconductor layers may be provided instead.

(Third embodiment)
Hereinafter, a lateral high-breakdown-voltage semiconductor switching element according to a third embodiment of the present invention and a switching power supply device using the same will be described with reference to the drawings.

FIG. 11 is a cross-sectional view showing an example of the configuration of the high voltage semiconductor switching element of the present embodiment. As shown in FIG. 11, the high withstand voltage semiconductor switching element of the present embodiment is different from the second embodiment shown in FIG. 10 in that, for example, a concentration of 1 is used instead of the RESURF region 217 of the second embodiment. The N-type RESURF region 222 having the p-type semiconductor layer 221 of about × 10 ¹⁶ / cm ³ at a deeper position is provided. Specifically, the p-type semiconductor layer 221 is formed at a position deeper than the p-type semiconductor layer 216 in the RESURF region 217 of the second embodiment, and similarly to the second embodiment, the portion not shown in the figure. Are electrically connected to the base region 204 (ie, the emitter / source region 206).

  According to the third embodiment, compared to the second embodiment shown in FIG. 10, the desurfing layer 222 is more easily expanded in the resurf region 222 at the time of reverse bias. Since it can be formed with a higher impurity concentration than the RESURF region 217, the same effect as in the second embodiment can be obtained more remarkably.

  In the present embodiment, one p-type semiconductor layer 221 is provided in the RESURF region 222, but a plurality of p-type semiconductor layers may be provided instead.

(Fourth embodiment)
Hereinafter, a lateral high-breakdown-voltage semiconductor switching element and a switching power supply device using the same according to a fourth embodiment of the present invention will be described with reference to the drawings.

FIG. 12 is a plan view showing an example of the configuration of the high voltage semiconductor switching element of the present embodiment. As shown in FIG. 12, the high voltage semiconductor switching element of this embodiment is different from the first embodiment shown in FIGS. 1 to 3 in the p ⁺ -type collector region 203 of the first embodiment. Instead, a p ⁺ type collector region 215 having a width smaller than that of the p ⁺ type collector region 203, for example, a concentration of about 1 × 10 ¹⁹ / cm ³ is formed, and the p ⁺ type collector region 215 and the RESURF region 202 In the meantime, an N-type buffer layer 214 having an impurity concentration higher than that of the RESURF region 202, for example, a concentration of about 1 × 10 ¹⁷ / cm ³ is provided. That is, the N-type buffer layer 214 is disposed around the collector region 215 of this embodiment.

  According to the fourth embodiment, since the efficiency of injection of holes from the collector region 215 to the RESURF region 202 is reduced, for example, the fall time (tf) can be shortened and improved.

  In this embodiment, the collector side modification of the semiconductor switching element of the present invention has been described. Needless to say, various modifications may be made without departing from the gist of the present invention.

  In the first to fourth embodiments, the semiconductor switching element of the present invention is provided on the P-type semiconductor substrate 201 on which the N-type RESURF region 202, 217 or 222 is formed. Instead, the P-type RESURF is provided. You may provide the semiconductor switching element of this invention in the N type semiconductor substrate in which the area | region was formed.

  The present invention relates to a high withstand voltage semiconductor switching element and a switching power supply device using the same, and is very useful because it has a special effect that loss can be reduced over the entire region from a light load to a heavy load.

4 transformer 11 primary side rectifying and smoothing circuit 12 main circuit 13 high voltage semiconductor switching element 14 voltage control circuit 15 starting circuit 16 and 17 of voltage control circuit 14 input terminal 21 secondary side rectifying and smoothing circuit 22 rectifier diode 23 choke coil 24 first Output capacitor 25 second output capacitor 26 high potential side output terminal 27 low potential side output terminal 29 photocoupler 31 diode bridge 32 input capacitor 41 primary winding 42 secondary winding 43 auxiliary winding 51 high withstand voltage JFET section 201 P ⁻ type semiconductor substrate 202 N type RESURF region 203 p ⁺ type collector region 204 p type base region 205 P ⁺ type contact region 206 N ⁺ type emitter / source region 207 field insulating film 208 interlayer film 209 gate insulating film 210 gate electrode 211 Collector / drain electrode 212 Emitter / source electrode 213 N ⁺ type drain region 214 N type buffer layer 215 p ⁺ type collector region 216 p type semiconductor layer 217 High concentration N type resurf region 218 N ⁺ type termination drain region 219 N ⁺ type first 2 drain region 220 second drain electrode 221 p-type semiconductor layer 222 high concentration N-type RESURF region

Claims (12)

An N-type region formed on the surface of the semiconductor substrate;
A P-type base region formed adjacent to the N-type region in the semiconductor substrate;
An N-type emitter / source region formed in the base region apart from the N-type region;
A gate insulating film formed to cover the base region in a portion between the emitter / source region and the N-type region;
A gate electrode formed on the gate insulating film;
An N-type drain region formed in the N-type region apart from the base region;
A P-type collector region formed in the N-type region apart from the base region;
A collector / drain electrode formed on the semiconductor substrate and electrically connected to both the collector region and the drain region;
An emitter / source electrode formed on the semiconductor substrate and electrically connected to both the base region and the emitter / source region;
When a positive voltage is applied to the gate electrode and the collector / drain electrode with respect to the emitter / source electrode, the collector / drain electrode is applied to the collector / drain electrode according to the magnitude of the collector voltage applied to the collector / drain electrode. The magnitude of the flowing collector current changes,
The first ratio of the change amount of the collector current to the change amount of the collector voltage when the magnitude of the collector voltage is larger than the predetermined voltage Vch, and the magnitude of the collector voltage is higher than the predetermined voltage Vch. The second ratio of the change amount of the collector current to the change amount of the collector voltage in the case of being small is different,
The high withstand voltage semiconductor switching element, wherein the first ratio is larger than the second ratio. The high voltage semiconductor switching element according to claim 1,
When the magnitude of the collector voltage is smaller than the predetermined voltage Vch, the emitter / source passes from the collector / drain electrode through the drain region, the N-type region, the base region, and the emitter / source region. A current flows to the electrode, and the current lowers the potential of the N-type region around the collector region so that holes are injected from the collector region to the N-type region at least compared to the collector region. ,
The high withstand voltage semiconductor switching element, wherein the collector voltage when the holes start to be injected into the N-type region is equal to the predetermined voltage Vch. The high voltage semiconductor switching element according to claim 1 or 2,
The collector region and the drain region are each composed of a plurality of separated parts,
In the direction perpendicular to the direction from the collector region to the emitter / source region, each part of the collector region and each part of the drain region are arranged so as to alternately contact each other. High voltage semiconductor switching element. In the high voltage semiconductor switching device according to claim 3,
The high breakdown voltage semiconductor switching element, wherein the length of each part of the collector region and the length of each part of the drain region in the direction from the collector region to the emitter / source region are equal. In the high voltage semiconductor switching device according to claim 3 or 4,
A high withstand voltage semiconductor switching element, wherein a length of each portion of the collector region in a direction perpendicular to a direction from the collector region to the emitter / source region is 48 μm or less. In the high voltage semiconductor switching element according to any one of claims 3 to 5,
The arrangement of each part of the collector region and each part of the drain region is terminated by a terminal part that is a part of the drain region,
In the N-type region, another N-type drain region is formed apart from the base region,
On the semiconductor substrate, another drain electrode electrically connected to the other drain region is formed,
The other drain region and the terminal end of the drain region are electrically connected via the N-type region,
Of the N-type region, at least a part of the region located between the other drain region and the terminal end of the drain region is narrower than the other part, whereby the collector / drain electrode is formed. A high withstand voltage semiconductor switching element, wherein when a voltage of a predetermined value or more is applied, a current path from the terminal end of the drain region to the other drain region is pinched off by an electric field effect. The high breakdown voltage semiconductor switching element according to any one of claims 1 to 6,
An N-type buffer layer having an impurity concentration higher than that of the N-type region is provided between the collector region and the N-type region. In the high voltage semiconductor switching element according to any one of claims 1 to 7,
The high breakdown voltage semiconductor switching element, wherein the N-type region is a RESURF region. In the high voltage semiconductor switching element according to any one of claims 1 to 8,
One or more P-type semiconductor layers electrically connected to the base region are formed in the N-type region. A semiconductor switching element to which an input DC voltage is applied, a voltage control circuit for controlling opening and closing of the semiconductor switching element, a primary winding electrically connected to an output terminal of the semiconductor switching element, and the primary winding A switching power supply comprising: a magnetically coupled secondary winding; and a rectifying / smoothing circuit that rectifies and smoothes a voltage induced in the secondary winding and supplies an output DC voltage to a load,
A switching power supply device using the high voltage semiconductor switching element according to claim 1 as the semiconductor switching element. In the switching power supply device according to claim 10,
The high-voltage semiconductor switching element according to claim 6 is used as the semiconductor switching element.
A start circuit for starting the voltage control circuit;
The switching power supply device, wherein the other drain electrode of the high-breakdown-voltage semiconductor switching element and the starter circuit are electrically connected. The switching power supply device according to claim 10 or 11,
An auxiliary winding magnetically coupled to both the primary winding and the secondary winding;
A switching power supply apparatus using a ringing choke converter system in which a voltage induced in the auxiliary winding is applied to a gate terminal of the semiconductor switching element through the voltage control circuit.

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