Disclosure of Invention
In view of the above, the present invention is directed to an IGBT with an overcurrent limiting function, a circuit structure and a polysilicon to improve endurance time.
Specifically, the present invention provides a polysilicon having an overcurrent limiting function, the polysilicon including: the IGBT overcurrent protection device comprises a main Insulated Gate Bipolar Transistor (IGBT) area, a separation area and a sensing IGBT area, wherein the separation area is positioned between the main IGBT area and the sensing IGBT area, and the separation area is provided with an overcurrent limitation area for carrying out overcurrent limitation on the IGBT;
the over-current limiting region is provided with a Zener diode, a bipolar over-current limiting triode, a first temperature compensation diode, a second temperature compensation diode, a first detection resistor and a second detection resistor which are used for jointly realizing an over-current limiting function on SiO 2;
an emitter is arranged above the main IGBT region; an n-type drift region is arranged below the main IGBT region, the separation region and the sensing IGBT region, an n + -type buffer region is arranged below the n-type drift region, a p + -type collector region is arranged below the n + -type buffer region, and the collector is connected below the p + -type collector region.
Further, the Zener diode, the bipolar over-current limiting triode, the first temperature compensation diode, the second temperature compensation diode, the first detection resistor and the second detection resistor are formed by growing a substrate in a high-temperature deposition Poly-Si and laser annealing mode.
Furthermore, the Zener diode, the bipolar over-current limiting triode, the first temperature compensation diode, the second temperature compensation diode, the first detection resistor and the second detection resistor are formed by growing a substrate in a local epitaxial growth and laser annealing mode.
Furthermore, the Zener diode, the bipolar over-current limiting triode, the first temperature compensation diode, the second temperature compensation diode, the first detection resistor and the second detection resistor are formed by growing a substrate in an SOI substrate mode.
The invention provides a method for constructing polycrystalline silicon with an over-current limiting function, wherein the polycrystalline silicon comprises the following steps: the IGBT device comprises a main Insulated Gate Bipolar Transistor (IGBT) area, a separation area and a sensing IGBT area, wherein the separation area is positioned between the main IGBT area and the sensing IGBT area;
the method comprises the following steps:
an overcurrent limiting area used for carrying out overcurrent limiting on the IGBT is arranged in the separation area;
the over-current limiting region is provided with a Zener diode, a bipolar over-current limiting triode, a first temperature compensation diode, a second temperature compensation diode, a first detection resistor and a second detection resistor which are used for jointly realizing an over-current limiting function on SiO 2;
an emitter is arranged above the main IGBT region; an n-type drift region is arranged below the main IGBT region, the separation region and the sensing IGBT region; and
an n + -type buffer region is provided below the n-type drift region, a p + -type collector region is provided below the n + -type buffer region, and the collector is connected below the p + -type collector region.
Further, the Zener diode, the bipolar over-current limiting triode, the first temperature compensation diode, the second temperature compensation diode, the first detection resistor and the second detection resistor are formed by growing a substrate in a high-temperature deposition Poly-Si and laser annealing mode.
Furthermore, the Zener diode, the bipolar over-current limiting triode, the first temperature compensation diode, the second temperature compensation diode, the first detection resistor and the second detection resistor are formed by growing a substrate in a local epitaxial growth and laser annealing mode.
Furthermore, the Zener diode, the bipolar over-current limiting triode, the first temperature compensation diode, the second temperature compensation diode, the first detection resistor and the second detection resistor are formed by growing a substrate in an SOI substrate mode.
The IGBT with the overcurrent limiting function breaks through the trade-off relation between Vce (sat) and tolerance time by having the high-speed overcurrent limiting function, and realizes reasonable tolerance time under the condition of extremely large short circuit.
Detailed Description
The exemplary embodiments of the present invention will now be described with reference to the accompanying drawings, however, the present invention may be embodied in many different forms and is not limited to the embodiments described herein, which are provided for complete and complete disclosure of the present invention and to fully convey the scope of the present invention to those skilled in the art. The terminology used in the exemplary embodiments illustrated in the accompanying drawings is not intended to be limiting of the invention. In the drawings, the same units/elements are denoted by the same reference numerals.
Unless otherwise defined, terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Further, it will be understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense.
Referring to fig. 1, as a preferred embodiment of the IGBT with an overcurrent limiting function according to the present invention, the IGBT with an overcurrent limiting function includes: the IGBT driving circuit comprises a main IGBT region, a separation region and a sensing IGBT region, wherein the separation region is positioned between the main IGBT region and the sensing IGBT region, a plurality of grids are arranged in the main IGBT region and the sensing IGBT region, and the separation region is provided with an overcurrent limiting region for limiting the overcurrent of the IGBT; no trench gate is disposed in the separation region;
an emitter is arranged above the main IGBT region; an n-type drift region is arranged below the main IGBT region, the separation region and the sensing IGBT region, an n + -type buffer region is arranged below the n-type drift region, a p + -type collector region is arranged below the n + -type buffer region, and the collector is connected below the p + -type collector region.
Preferably, the length of the separation region is 2 times the hole carrier diffusion length in the separation region. That is, the distance between the sense IGBT region and the main IGBT region should be 2 times the hole carrier diffusion length of that region to avoid interaction with other cells in the IGBT chip.
In specific operation, a base region is arranged between the grid electrodes, and n + type emitting regions are arranged on two sides of the upper surface of each base region and connected with the emitter; and the p + type base region is arranged between the n + type emitter regions on two sides of each base region.
The current detection IGBT with the current limiting and protecting element of the present embodiment can prevent an overcurrent and short circuit condition, the separation region between the main IGBT and the sensing IGBT is arranged without any trench gate unit in order to avoid the interaction between the main IGBT part and the sensing IGBT part, and the separation region can avoid the interaction, and the overcurrent limiting function region, via which the withstand time is improved, is formed on the separation region.
Fig. 2 is a circuit diagram of a circuit structure with an overcurrent limiting function according to an embodiment of the present invention, and as shown in fig. 2, the circuit structure with an overcurrent limiting function is used for an IGBT, and the circuit structure includes: the temperature control circuit comprises a controller, a comparator, an overcurrent limiting diode ZD, an overcurrent limiting triode Tr, a current mirror detection IGBT, a first detection resistor R1, a second detection resistor R2, a first temperature compensation diode D1 and a second temperature compensation diode D2;
the emitter of the current mirror detection IGBT is connected with a reference voltage end on one hand and is connected with the base of the over-current limiting triode on the other hand;
the base electrode of the over-current limiting triode is connected with the reference voltage end through the first temperature compensation diode, the first detection resistor, the second temperature compensation diode and the second detection resistor which are sequentially connected; the collector of the over-current limiting triode is connected with the base of the current mirror detection IGBT through the over-current limiting diode; an emitting electrode of the over-current limiting triode is connected with the reference voltage end;
the positive input end of the comparator is connected with the connection point between the first detection resistor R1 and the second temperature compensation diode; the negative input end of the comparator is connected with the reference voltage end;
the output end of the comparator is connected with the input end of the controller, and the output end of the controller is connected with the base electrode of the current mirror detection IGBT.
Specifically, the overcurrent limiting diode is a zener diode.
Specifically, the current mirror detection IGBT is composed of tens of thousands of small batteries connected in parallel.
Specifically, the negative input end of the comparator is connected with the positive electrode of a reference voltage source, and the negative electrode of the reference voltage source is connected with the reference voltage end. The temperature coefficients of the first temperature compensation diode and the second temperature compensation diode are about-1.8 mV/DEG C, and the temperature coefficients of the first detection resistor and the second detection resistor sensing resistor are about +1.5 mV/DEG C. The breakdown voltage of the Zener diode is set to be 10-12V so as to limit safe overcurrent.
The present embodiment limits the IGBT, the resistors R1, R2, the temperature compensation diodes D1, D2, the overcurrent limiting transistor Tr, and the zener diode ZD to a given gate voltage by the current mirror detection of the overcurrent limiting circuit. The specific working mode is as follows:
the current sensing IGBT is composed of tens of thousands of small batteries connected in parallel, and the ratio of the number of the main IGBT to the number of the sensing IGBT exceeds thousands to 1. The overcurrent across the resistors R1, R2 and the temperature compensating diodes D1, D2 generates Vb between the base and emitter of the bipolar transistor. When Vb exceeds b-e and the built-in voltage exceeds about 0.8V, the overcurrent limiting triode Tr is turned on. At the same time, the gate voltage Vg is immediately lowered from the normal operation gate voltage 15V to about 10-12V, achieving that at the start of overcurrent limitation, the gate voltage drops rapidly to a prescribed value, but a limited overcurrent still continues to flow through the sense resistor, and the sense current flows through R1, R2D 1 and D2, and the resulting sense voltage Vs is compared with the specified reference voltage Vref. When Vs exceeds Vref, the controller begins to control soft turn off the IGBT.
To compensate for the temperature dependence of the shunt resistance and the sense current, additional temperature compensating diodes D1 and D2 are added, the temperature coefficient of the diodes being about-1.8 mV/deg.C and the temperature coefficient of the sense resistor being about +1.5 mV/deg.C, in order to achieve the acceptably accurate level of control needed to protect the IGBT from large short circuit conditions.
In this embodiment, when a short circuit occurs, the overcurrent limiting circuit starts to operate first, and Vb instantaneously exceeds the emitter-base voltage by about 0.8V. In short, the bipolar transistor arranged in the circuit starts to conduct and Vg momentarily drops to the overcurrent limit ZD voltage, about 10V to 12V, and the overcurrent has to limit the saturation current at a given Vge. Then, when the overcurrent detection circuit detects a voltage exceeding the prescribed voltage limit, it turns off the IGBT, achieving that the IGBT will remain safe, so that the safety of the IGBT will be maintained at least 10 μ sec even under severe circuit conditions.
Fig. 3 is a cross-sectional view of a polysilicon with an over-current limiting function according to an embodiment of the present invention, and fig. 3 shows a polysilicon with an over-current limiting function, which includes: the IGBT overcurrent protection device comprises a main IGBT region, a separation region and a sensing IGBT region, wherein the separation region is positioned between the main IGBT region and the sensing IGBT region, and the separation region is provided with an overcurrent limiting region for carrying out overcurrent limitation on the IGBT;
the over-current limiting region is provided with a Zener diode, a bipolar over-current limiting triode, a first temperature compensation diode, a second temperature compensation diode, a first detection resistor and a second detection resistor which are used for jointly realizing an over-current limiting function on SiO 2;
an emitter is arranged above the main IGBT region; an n-type drift region is arranged below the main IGBT region, the separation region and the sensing IGBT region, an n + -type buffer region is arranged below the n-type drift region, a p + -type collector region is arranged below the n + -type buffer region, and the collector is connected below the p + -type collector region.
Specifically, the zener diode, the bipolar overcurrent limiting triode, the first temperature compensation diode, the second temperature compensation diode, the first detection resistor, and the second detection resistor are formed by growing a substrate in any one of three ways, including: high-temperature deposition of Poly-Si and laser annealing; local epitaxial growth and laser annealing; and an SOI substrate.
In order to realize an IGBT with built-in more precise current limiting control, it is necessary to grow a high Si quality layer on SiO2 using high temperature Poly Si CVD growth and high temperature growth, and a Lase annealing or epitaxial growth layer on SiO2 is developed, so it can realize high performance elements such as ZD, bipolar Tr, diode and resistor, and realize precise sensing and limiting functions using bip.tr, diode, zener diode and resistor formed on a high quality substrate layer. Silicon dioxide. The sense IGBT part is separated from the main IGBT part by applying a deep p-base and a normal p + region without any active region, as shown in fig. 3, and the ratio of the sense current to the main current is always maintained at 1 to several thousand to 1 to 20 ten thousand.
The present embodiment achieves excellent polysilicon quality by built-in components, i.e., resistors, diodes, bipolar transistors and zener diodes, being polysilicon with large grain size fabricated on SiO2, and applies specific growth and recrystallization techniques, enabling to keep the IGBT free from any short circuit and over-current conditions, thus breaking through the trade-off relationship between vce (sat) and short circuit withstand capability, enabling lower vce (sat) without sacrificing withstand capability, with temperature compensation and high speed reaction to short circuit conditions formed at higher substrate crystal quality levels achieved by using specified polysilicon deposition and laser annealing and local epitaxial growth layers.
Fig. 4 is a flow chart of a method 400 for forming polysilicon with an over-current limiting function according to an embodiment of the present invention. The polycrystalline silicon with the overcurrent limiting function comprises: the IGBT device comprises a main IGBT region, a separation region and a sensing IGBT region, wherein the separation region is located between the main IGBT region and the sensing IGBT region.
In step 401, an overcurrent limiting region for overcurrent limiting of the IGBT is provided in the isolation region.
In step 402, the over-current limiting region is provided with a zener diode, a bipolar over-current limiting triode, a first temperature compensation diode, a second temperature compensation diode, a first detection resistor and a second detection resistor on SiO2 for jointly realizing an over-current limiting function.
At step 403, an emitter is disposed over the main IGBT region; and an n-type drift region is provided below the main IGBT region, the separation region and the sensing IGBT region.
In step 404, an n + -type buffer region is disposed below the n-type drift region, a p + -type collector region is disposed below the n + -type buffer region, and the collector is connected below the p + -type collector region.
Specifically, the zener diode, the bipolar overcurrent limiting triode, the first temperature compensation diode, the second temperature compensation diode, the first detection resistor, and the second detection resistor are formed by growing a substrate in any one of three ways, including: high-temperature deposition of Poly-Si and laser annealing; local epitaxial growth and laser annealing; and an SOI substrate.
In order to realize an IGBT with built-in more precise current limiting control, it is necessary to grow a high Si quality layer on SiO2 using high temperature Poly Si CVD growth and high temperature growth, and a Lase annealing or epitaxial growth layer on SiO2 is developed, so it can realize high performance elements such as ZD, bipolar Tr, diode and resistor, and realize precise sensing and limiting functions using bip.tr, diode, zener diode and resistor formed on a high quality substrate layer. Silicon dioxide. The sense IGBT part is separated from the main IGBT part by applying a deep p-base and a normal p + region without any active region, as shown in fig. 3, and the ratio of the sense current to the main current is always maintained at 1 to several thousand to 1 to 20 ten thousand.
The present embodiment achieves excellent polysilicon quality by built-in components, i.e., resistors, diodes, bipolar transistors and zener diodes, being polysilicon with large grain size fabricated on SiO2, and applies specific growth and recrystallization techniques, enabling to keep the IGBT free from any short circuit and over-current conditions, thus breaking through the trade-off relationship between vce (sat) and short circuit withstand capability, enabling lower vce (sat) without sacrificing withstand capability, with temperature compensation and high speed reaction to short circuit conditions formed at higher substrate crystal quality levels achieved by using specified polysilicon deposition and laser annealing and local epitaxial growth layers.
The invention has been described with reference to a few embodiments. However, other embodiments of the invention than the one disclosed above are equally possible within the scope of the invention, as would be apparent to a person skilled in the art from the appended patent claims.
Generally, all terms used in the claims are to be interpreted according to their ordinary meaning in the technical field, unless explicitly defined otherwise herein. All references to "a/an/the [ device, component, etc ]" are to be interpreted openly as referring to at least one instance of said device, component, etc., unless explicitly stated otherwise. The steps of any method disclosed herein do not have to be performed in the exact order disclosed, unless explicitly stated.