Semiconductor device and manufacturing method

Abstract

The invention discloses a semiconductor device. A drift region of the semiconductor device comprises a slowly-changing drift region with doping concentration increased slowly, and the slowly-changing drift region is positioned on the back of the drift region, is provided with a slowly-increasing area with the width more than or equal to one micrometer and is capable of blocking an electric field of the drift region and keeping low on resistance. Meanwhile, the defect that a built-in electric field in a field blocking layer is large in an existing field blocking type semiconductor device can be eliminated by the aid of the slowly-changing drift region which is set with large width and capable of increasing slowly, so that current fall speed can be controlled effectively when the semiconductor device is turned off, and reliability of the semiconductor device can be improved. By arranging field blocking layers on the back of the slowly-changing drift region, the semiconductor device has the advantages that hole emitting efficiency of a terminal region of the device can be reduced, and current density of a junction region of the device is decreased, so that device reliability can be improved. The invention further discloses a semiconductor device manufacturing method.

Description

technical field [0001] The invention relates to the field of manufacturing semiconductor integrated circuits, in particular to a semiconductor device; the invention also relates to a method for manufacturing the semiconductor device. Background technique [0002] In semiconductor high-voltage devices, whether it is an insulated gate bipolar transistor (IGBT), a fast recovery diode (FRD), or a MOSFET, when the gate of the device is positively biased, the device is turned on. The power consumption is the smallest, that is, the on-state voltage drop of the device is expected to be small, and the on-state voltage drop of the device can be directly reduced by using a thinner silicon chip, but the decrease in the thickness of the device will reduce the reverse breakdown of the device. Under the condition of pressure resistance, the two are a pair of contradictions. In order to solve the above contradictions, the field blocking layer is introduced into the semiconductor high-volta...

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Problems solved by technology

Since metal materials such as Al have been formed on the front of the device before annealing, the annealing temperature generally cannot be higher than 500 degrees Celsius when using ordinary thermal annealing technology, and the implanted field-blocking layer ions are not activated efficiently, and at the same time, they cannot reach the diffusion level. Effect

The use of laser annealing can greatly improve the efficiency, the depth that laser annealing can reach is limited, and the process cost is high, so it is impossible to activate for a long time, and there is no effective diffusion of impurities, so the obtained field blocking layer The ion distribution of the

This dramatic change in carrier concentration, in the process of changing the device from the on state to the off state, due to the large built-in electric field in the field blocking layer, accelerates the flow of electrons in the drift region during the on state. The speed of the N-type field-blocking layer causes a sharp drop in current and reduces the flexibility of the switch. It is easy to generate a high peak voltage under inductive load to make the device invalid; on the other hand, in a short time, the P+N on the back The blocking layer, that is, the PN junction of the P-type emitter 4 and the field blocking layer 3 is prone to cause a large difference between local electrons and holes, and a very high electric field is formed near the junction, which is also easy to cause the device to fail.

[0005] The area around the charge flow region of the existing field-blocking IGBT also includes the termination region and the junction region, the termination region is used to protect the unit structure of the charge flow region, and the junction region is the charge flow region. The transition region between the region and the terminal region, the drift region of the charge flow region, the terminal region and the junction region in the existing field-stop type IGBT are connected and are all formed by the silicon wafer 1 body, the holes entering the drift region of the terminal region and the junction region from the P-type emitter 4 also participate in conduction, and when the existing field-blocking IGBT is turned off, the holes enter the Holes in the drift region of the terminal region and the junction region will be extracted from the contact hole in the junction region, so that the current density in this region is higher than the current density in the charge flow region in the middle of the device, so that the failure of the device occurs in the area

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