阅读说明：本技术 一种带有内置电流传感器的沟槽igbt器件结构及制作方法 (Groove IGBT device structure with built-in current sensor and manufacturing method ) 是由 汤艺 永福 王良元 徐泓 于 2019-07-29 设计创作，主要内容包括：一种带有内置电流传感器的沟槽IGBT器件结构及制作方法,该制造方法包括如下步骤：在选定的N型外延硅衬底或者区熔片上定义有源区,生长场区氧化层；选择性的定义深P阱或者不做此步骤；光刻沟槽图形,干法刻蚀硅衬底；生长栅极氧化层,淀积原位参杂的多晶硅材料填充沟槽；然后光刻栅极图形,刻蚀多晶硅形成顶层结构的栅极；注入P型杂质并扩散形成浅P阱作为沟道区；光刻N型源区注入N型杂质；然后淀积氧化层或者氮化硅等绝缘材料并退火致密,光刻接触孔,刻蚀绝缘层裸露出之前形成的所有元胞的P阱区和N型源区硅表面；注入P型杂质并激活,溅射顶层金属,光刻刻蚀顶层金属,淀积钝化层,光刻刻蚀钝化层,合金完成顶层结构的制作。(A groove IGBT device structure with a built-in current sensor and a manufacturing method thereof are disclosed, the manufacturing method comprises the following steps: defining an active area on the selected N-type epitaxial silicon substrate or the selected zone melting plate, and growing a field area oxide layer; selectively defining a deep P well or not performing the step; photoetching a groove pattern, and etching the silicon substrate by a dry method; growing a grid oxide layer, and depositing an in-situ doped polycrystalline silicon material to fill the groove; then photoetching a grid electrode pattern, and etching the polycrystalline silicon to form a grid electrode of a top layer structure; injecting P-type impurities and diffusing to form a shallow P well as a channel region; photoetching an N-type source region and injecting N-type impurities; then depositing an oxide layer or silicon nitride and other insulating materials, annealing and compacting, photoetching a contact hole, and etching the insulating layer to expose the silicon surfaces of the P well region and the N type source region of all the cells formed before; injecting P-type impurities and activating, sputtering top metal, photoetching and etching the top metal, depositing a passivation layer, photoetching and etching the passivation layer, and finishing the manufacturing of the top structure by using the alloy.)

1. A trench IGBT device structure with a built-in current sensor is characterized by comprising a main IGBT and a current sampling IGBT which are integrally arranged in parallel, wherein the main IGBT structure is isolated from the current sampling IGBT through a trench, and the main IGBT and the current sampling IGBT respectively comprise an N-type substrate, a P-type substrate, an N-type charge storage layer, a P-type channel region, a trench and a contact hole; an N-type charge storage layer and a P-type channel region are sequentially arranged on the N-type substrate, and a P-type substrate is arranged at the bottom of the N-type substrate; the top of the P-type channel region is provided with a plurality of grooves of which the bottoms are communicated with the N-type substrate, at least one group of contact holes are formed between the grooves through an N-type source region, and a groove oxide layer and polycrystalline silicon are arranged in each groove; the groove penetrates through the P-type channel region, the N-type charge storage layer and the N-type substrate, and the groove oxidation layer is arranged in the groove and covers the surface of each groove.

2. A method for manufacturing the trench IGBT device structure according to claim 1, wherein the manufacturing method comprises the steps of:

1) defining an active area on the selected N-type substrate or the selected zone melting sheet, and growing a field area oxide layer;

2) according to the design of a terminal structure and an active area unit cell, selectively defining a deep P well or not performing the step;

3) photoetching a groove pattern, and etching the silicon substrate by a dry method, wherein the groove simultaneously defines an active area grid groove and a groove for isolating the current sampling IGBT;

4) growing a grid oxide layer, and depositing an in-situ doped polycrystalline silicon material to fill the groove; then photoetching a grid electrode pattern, and etching the polycrystalline silicon to form a grid electrode of a top layer structure;

5) injecting P-type impurities and diffusing to form a shallow P well (P-base) as a channel region; a shallow P-well channel region (P-base) can also be optionally formed before defining the trench;

6) photoetching an N-type source region and injecting N-type impurities; then depositing an oxide layer or silicon nitride and other insulating materials, annealing and compacting, photoetching a contact hole, and etching the insulating layer to expose the silicon surfaces of the P well region and the N type source region of all the cells formed before;

7) injecting P-type impurities and activating to ensure ohmic contact between the P well region and the top metal, sputtering the top metal, photoetching the top metal, depositing a passivation layer, photoetching the passivation layer, and alloying to finish the manufacture of the top structure; and then the back of the silicon chip is thinned to a specific thickness, P-type or N-type and P-type impurities are injected into the back, an IGBT collector region or an FS-IGBT with a field stop layer is formed through low-temperature annealing or laser annealing, and finally back metal is deposited through a sputtering or evaporation method to complete the manufacturing process of the whole IGBT device and the current sensor.

3. The method of claim 2, wherein the method is to isolate the inactive active region from the active channel region by using a transition region trench and a deep P-well design.

4. The method for manufacturing the trench IGBT device according to claim 2, wherein in step 3), the trench for isolating the current sensor is connected to an emitter.

Technical Field

The invention belongs to the technical field of manufacturing of IGBT devices, and particularly relates to a groove IGBT device structure with a built-in current sensor and a manufacturing method of the groove IGBT device structure.

Background

As a main representative of a new power semiconductor device, the IGBT is widely used in the fields of industry, information, new energy, medicine, transportation, military, and aviation. At present, the voltage resistance of the IGBT device on the market reaches 6500V, the current of a single tube core reaches 200A, and the frequency reaches 300 KHz. In the high-frequency high-power field, no other device can replace the high-frequency high-power field. With the continuous progress of semiconductor materials and processing technologies, IGBT devices adopting the trench technology have become mainstream products. Meanwhile, the requirement on the electrical performance of the trench IGBT device is higher and higher. In practical applications, the system often needs to be able to detect the occurrence of an overcurrent condition as soon as possible so as to respond in time to ensure the protection and normal operation of the system. External current sensors typically increase the complexity and area of the module and circuitry, and are relatively delayed in response time. The built-in sensor of the IGBT chip can effectively provide information of current in the chip in time, thereby simplifying a circuit and protecting a system.

Disclosure of Invention

The invention aims to solve the technical problem of providing a trench IGBT device structure with a built-in current sensor, which is simple in process control, compatible with a general trench IGBT process and free from increasing the process manufacturing cost, and a manufacturing method of the IGBT device structure.

The invention aims to solve the technical scheme that the trench IGBT device structure with the built-in current sensor comprises a main IGBT and a current sampling IGBT which are integrally arranged in parallel, wherein the main IGBT structure is isolated from the current sampling IGBT through a trench, and the main IGBT and the current sampling IGBT respectively comprise an N-type substrate, a P-type substrate, an N-type charge storage layer, a P-type channel region, a trench and a contact hole; an N-type charge storage layer and a P-type channel region are sequentially arranged on the N-type substrate, and a P-type substrate is arranged at the bottom of the N-type substrate; the top of the P-type channel region is provided with a plurality of grooves of which the bottoms are communicated with the N-type substrate, at least one group of contact holes are formed between the grooves through an N-type source region, and a groove oxide layer and polycrystalline silicon are arranged in each groove; the groove penetrates through the P-type channel region, the N-type charge storage layer and the N-type substrate, and the groove oxidation layer is arranged in the groove and covers the surface of each groove.

The manufacturing method comprises the following steps:

1) defining an active area on the selected N-type substrate or the selected zone melting sheet, and growing a field area oxide layer;

2) according to the design of a terminal structure and an active area unit cell, selectively defining a deep P well or not performing the step;

3) photoetching a groove pattern, and etching the silicon substrate by a dry method, wherein the groove simultaneously defines an active area grid groove and a groove for isolating the current sampling IGBT;

4) growing a grid oxide layer, and depositing an in-situ doped polycrystalline silicon material to fill the groove; then photoetching a grid electrode pattern, and etching the polycrystalline silicon to form a grid electrode of a top layer structure;

5) injecting P-type impurities and diffusing to form a shallow P well (P-base) as a channel region; a shallow P-well channel region (P-base) can also be optionally formed before defining the trench;

6) photoetching an N-type source region and injecting N-type impurities; then depositing an oxide layer or silicon nitride and other insulating materials, annealing and compacting, photoetching a contact hole, and etching the insulating layer to expose the silicon surfaces of the P well region and the N type source region of all the cells formed before;

7) injecting P-type impurities and activating to ensure ohmic contact between the P well region and the top metal, sputtering the top metal, photoetching the top metal, depositing a passivation layer, photoetching the passivation layer, and alloying to finish the manufacture of the top structure; and then the back of the silicon chip is thinned to a specific thickness, P-type or N-type and P-type impurities are injected into the back, an IGBT collector region or an FS-IGBT with a field stop layer is formed through low-temperature annealing or laser annealing, and finally back metal is deposited through a sputtering or evaporation method to complete the manufacturing process of the whole IGBT device and the current sensor.

Furthermore, the manufacturing method is to use transition region grooves and deep P-well design to isolate the ineffective active region and the effective channel region.

Further, in step 3), the trench for isolating the current sensor is connected to the emitter.

The invention has the beneficial technical effects that: the process control is simple, the method is compatible with the general groove type IGBT process, the process manufacturing cost does not need to be increased, the sampling proportion of the sensor is stable, and the method achieves a good isolation effect with the main IGBT.

Drawings

FIG. 1 is a structural diagram of a current sensor of a conventional trench IGBT device;

FIG. 2 is a structural diagram of another conventional trench IGBT device current sensor;

fig. 3 is a structural diagram of another conventional trench IGBT device current sensor;

FIG. 4 is a schematic cross-sectional view of a trench IGBT device current sensor in accordance with the present invention;

FIG. 5 is a schematic diagram of a top view structure of a trench IGBT device current sensor according to the present invention;

FIG. 6 is a schematic diagram of a first top view structure of a trench IGBT device current sensor according to the present invention;

FIG. 7 is a schematic diagram of a second top view of a trench IGBT device current sensor according to the present invention;

FIG. 8 is a schematic circuit diagram of a current sampling IGBT and a main IGBT used in the present invention;

FIG. 9 is another schematic structural diagram of a trench IGBT device current sensor according to the present invention;

fig. 10 is a schematic top view of the structure of fig. 7.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more clearly understood by those skilled in the art, the present invention is further described with reference to the accompanying drawings and examples.

In order to improve the working safety of a trench IGBT device in a system without increasing the complexity of a circuit system, a current sensor with a built-in chip needs to be designed, and a commonly adopted method is to arrange a small IGBT area in an active area and output sampling current; however, if the current sensor region is not effectively isolated from the main IGBT region, a parasitic resistance exists between the current sensor region and the main IGBT, which easily causes the sampling current ratio of the sensor to be unstable, and meanwhile, the position of the sensor also plays an important role, and if the sensor is far away from the main IGBT, the sensor carrier is easily subjected to excessive extension resistance, thereby further affecting the sampling precision of the sensor.

Referring to fig. 1, in a conventional structure, a current sensor is disposed at the other end of a deep P-well, and due to impedance inside the deep P-well, a built-in resistor exists between the current sensor and a main IGBT; this causes a shunting of the emitter current, so that the current sampling density changes with a change in the external resistance; referring to fig. 2, the current sensor and the main IGBT are divided by two different deep P-wells, which has the advantages that the problem of intrinsic resistance connection is basically solved, but due to the distance between the deep P-wells, the effective region of the current sensor is far away from the effective region of the main IGBT, the spreading resistance of the current sensor carrier is greatly increased, and the sampling proportion is affected; the structure shown in fig. 3 appears to isolate the current sensor from the main IGBT with trenches, but in the third direction, the P-well between the trenches causes a built-in resistance between the current sensor and the main IGBT.

As shown in fig. 3-9, the trench IGBT device structure according to the present invention includes a main IGBT and a current sampling IGBT that are integrally arranged in parallel, the main IGBT structure is isolated from the current sampling IGBT by a trench, and the main IGBT and the current sampling IGBT each include an N-type substrate, a P-type substrate, an N-type charge storage layer, a P-type channel region, a trench, and a contact hole; an N-type charge storage layer and a P-type channel region are sequentially arranged on the N-type substrate, and a P-type substrate is arranged at the bottom of the N-type substrate; the top of the P-type channel region is provided with a plurality of grooves of which the bottoms are communicated with the N-type substrate, at least one group of contact holes are formed between the grooves through an N-type source region, and a groove oxide layer and polycrystalline silicon are arranged in each groove; the groove penetrates through the P-type channel region, the N-type charge storage layer and the N-type substrate, and the groove oxidation layer is arranged in the groove and covers the surface of each groove. The current sampling IGBT has the same structure as the main IGBT, shares a trench gate electrode and a collector on the back side with the main IGBT, but has an emitter separated from the gate electrode, and the electrical isolation between the emitter of the main IGBT is realized through the trench.

The manufacturing method comprises the following steps:

1) defining an active area on the selected N-type substrate or the selected zone melting sheet, and growing a field area oxide layer;

2) according to the design of a terminal structure and an active area unit cell, selectively defining a deep P well or not performing the step;

3) photoetching a groove pattern, and etching the silicon substrate by a dry method, wherein the groove simultaneously defines an active area grid groove and a groove for isolating the current sampling IGBT;

4) growing a grid oxide layer, and depositing an in-situ doped polycrystalline silicon material to fill the groove; then photoetching a grid electrode pattern, and etching the polycrystalline silicon to form a grid electrode of a top layer structure;

5) injecting P-type impurities and diffusing to form a shallow P well (P-base) as a channel region; a shallow P-well channel region (P-base) can also be optionally formed before defining the trench;

6) photoetching an N-type source region and injecting N-type impurities; then depositing an oxide layer or silicon nitride and other insulating materials, annealing and compacting, photoetching a contact hole, and etching the insulating layer to expose the silicon surfaces of the P well region and the N type source region of all the cells formed before;

7) injecting P-type impurities and activating to ensure ohmic contact between the P well region and the top metal, sputtering the top metal, photoetching the top metal, depositing a passivation layer, photoetching the passivation layer, and alloying to finish the manufacture of the top structure; and then the back of the silicon chip is thinned to a specific thickness, P-type or N-type and P-type impurities are injected into the back, an IGBT collector region or an FS-IGBT with a field stop layer is formed through low-temperature annealing or laser annealing, and finally back metal is deposited through a sputtering or evaporation method to complete the manufacturing process of the whole IGBT device and the current sensor.

The manufacturing method is to design and isolate an invalid active region and an effective channel region by utilizing a transition region groove and a deep P well; in step 3), the trench for isolating the current sensor is connected to the emitter.

FIGS. 4-5 are a diagram of trench isolation design, contact hole design and position structure of the current sensor of the trench IGBT device of the present invention, which is characterized in that the isolation of the current sensor from the main IGBT is ensured by the position of the trench and the contact hole, ensuring accurate sampling density. The cross-sectional view of fig. 4 shows that the isolation of the deep P-well is not provided between the current sensor and the main IGBT, but trench isolation is used, so that the problem of built-in resistor connection between the current sensor and the main IGBT is avoided, electrical isolation between the current sensor and the main IGBT is ensured, and the sampling ratio of the current sensor is ensured. And because the current sensor and the main IGBT are arranged in the same active region, the phenomenon that the sampling current density is too low due to the extension resistance of the current sensor is effectively avoided. Fig. 5 is a layout design of the present invention showing the provision of trench isolation in both the x and y directions, effectively separating the current sensor from the emitter of the main IGBT. In the arrangement of the contact hole, the contact hole of the current sensor is only limited in the P-well region, and the contact hole of the current sensor is prevented from being arranged in the deep P-well region at the edge. So as to ensure that the current sensor and the main IGBT can not generate built-in resistance due to the connection of the deep P well.

Fig. 6-10 illustrate a current sensor in which the present invention is applicable to and not limited to other trench types, IGBT and MOSFET, wherein several trench structures are illustrated.

The specific embodiments described herein are merely illustrative of the principles and utilities of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or change the above-mentioned embodiments without departing from the spirit and scope of the present invention. Accordingly, it is intended that all equivalent modifications or changes which can be made by those skilled in the art without departing from the spirit and technical spirit of the present invention be covered by the claims of the present invention.