Manufacturing method of IGBT (Insulated Gate Bipolar Translator) device and IGBT device

Abstract

The invention provides a manufacturing method of an IGBT device and the IGBT device, the manufacturing process is divided into four stages of a front surface process, a back surface process, a thinning process and a bonding process, and the manufacturing method comprises the following steps: manufacturing a front surface structure on the front surface of a first substrate by adopting a conventional IGBT front surface process; performing a thinning process on the back surface of the first substrate; manufacturing a back surface structure on the first side of the second substrate by adopting a conventional IGBT back surface process, wherein the other side of the second substrate is a second side; performing a thinning process on the second side of the second substrate; and carrying out bonding connection on the back surface of the first substrate and the second side of the second substrate. The manufacturing method of the IGBT device is compatible with the existing MOS (Metal Oxide Semiconductor) process, the front substrate and the back substrate can adopt the conventional manufacturing process, and the process difficulty and cost are not increased; the two substrates are thinned after the front and back processes, so that the problems that the back of the conventional IGBT ultrathin sheet is difficult to process and is easy to break and the like can be effectively avoided; the bonding process adopts a plasma activation process, the annealing temperature is about 200-400 DEG C, and the damage to the device structure due to high temperature is avoided.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor manufacturing, and in particular to a method for manufacturing an IGBT device. Background Art

[0002] In recent years, insulated gate bipolar transistor technology has developed rapidly and has become one of the most important high-power mainstream devices in the field of power electronics. IGBT is a new type of composite power device developed on the basis of metal oxide field effect transistor and bipolar transistor. It has the main advantages of both in terms of performance: high input impedance, low input drive power, small on-resistance, large current capacity, fast switching speed, etc. It is widely used in rail transportation, smart grid, electric vehicles, new energy and other fields.

[0003] Since IGBT devices generally need to withstand large currents, thinner chip thickness can reduce resistance and the corresponding heat, and improve device performance. Therefore, the industry generally uses thinning processes to reduce the thickness of the chip drift region, thereby reducing internal resistance and improving device performance. The thickness of IGBT is generally around 100um. If the Taiko process is used, it can be thinned to 50um. However, the strength of the thinned substrate itself is greatly reduced due to the reduction in thickness, resulting in warping, cracks, and easy breakage. The existing IGBT manufacturing process is divided into three stages according to the process: front process, thinning process, and back process. First, the front structure is completed on the substrate, and then the thickness is thinned from the back of the substrate to a specified value. Finally, the back structure is formed by injection, metallization, and other processes on the back of the substrate. This method requires compatibility with ultra-thin sheets. When the substrate is thinned to a smaller thickness, it is easy to cause warping and breakage problems, which puts high demands on the subsequent back process, increases the difficulty of the back process, and the production difficulty and cost are very high.

[0004] Therefore, it is necessary to provide a method for manufacturing an IGBT device to solve the above technical problems. Summary of the invention

[0005] The present invention provides a method for manufacturing an IGBT device and an IGBT device, which solve the problems of warping, cracking and the like after thinning of the substrate in the traditional method, which increases the difficulty of subsequent back-side processing and makes production difficult and costly.

[0006] In order to solve the above technical problem, a first aspect of the present invention provides a method for manufacturing an IGBT device, comprising the following steps:

[0007] S1. Providing a first substrate for forming a functional area of ​​a transistor in an IGBT device. The first substrate may be made of any semiconductor material that can be used to make a chip substrate;

[0008] S2. Using a conventional IGBT front process to manufacture a front structure in and on the first substrate, the surface with the front structure being the front surface of the first substrate, and the other surface away from the front surface being the back surface of the first substrate;

[0009] S3, performing a thinning process on the back side of the first substrate, grinding or chemical mechanical grinding from the back side of the substrate to thin the substrate, and determining the grinding thickness according to needs;

[0010] S4, providing a second substrate for forming the functional regions of the collector region and the field stop region in the IGBT device, and the second substrate may be made of the same material as the first substrate;

[0011] S5, using a conventional IGBT back surface process to manufacture a back surface structure in the second substrate and on the second substrate, wherein the side where the back surface structure is formed is the first side of the second substrate, and the other side away from the first side is the second side of the second substrate;

[0012] S6, performing a thinning process on the second side of the second substrate, grinding from the second side of the substrate by a grinding or chemical mechanical grinding process to thin the substrate, and determining the grinding thickness according to needs;

[0013] S7, performing plasma cleaning on the back side of the first substrate;

[0014] S8, plasma cleaning the second side of the second substrate;

[0015] S9, bonding the back side of the first substrate and the second side of the second substrate, that is, bonding the substrates made of the same material to form an IGBT device.

[0016] In some embodiments of the first aspect, the front side process includes a metal process of a MOSFET; and the IGBT back side process includes an IGBT back side ion implantation, an annealing process, and a metal process.

[0017] In some embodiments of the first aspect, the back side process can also be made by doped EPI growth, annealing process and metal process. The doped EPI growth is to grow epitaxial layers of N-type impurities and P-type impurities with different doping concentrations on the first side of the second substrate by doped EPI growth to form the IGBT back side structure.

[0018] In some embodiments of the first aspect, high temperature annealing in the back side process may be performed by high temperature furnace annealing, RTA rapid annealing, laser annealing or other high temperature annealing methods.

[0019] In some embodiments of the first aspect, a chemical mechanical polishing process is used to perform polishing from the back side of the first substrate and the second side of the second substrate respectively to thin the substrates.

[0020] In some embodiments of the first aspect, the thickness of the first substrate after thinning is 25 μm to 100 μm, and the thickness of the second substrate after thinning is 25 μm to 100 μm.

[0021] In some embodiments of the first aspect, the first substrate and the second substrate are connected by a plasma activated bonding process, and the bonding annealing temperature is about 200-400°C.

[0022] A second aspect of the present invention provides an IGBT device formed by the method for forming an IGBT device according to any one of the first aspects.

[0023] In some embodiments of the second aspect, the IGBT device includes a first substrate and a second substrate: the first substrate includes a front side and a back side, the front side is provided with a front side structure, and the front side structure is provided with a front side metal layer and a front side passivation layer;

[0024] The second substrate comprises a first side and a second side, wherein the first side is provided with a back surface structure, and a back surface metal layer is provided inside the back surface structure;

[0025] The back side of the first substrate is bonded to the second side of the second substrate, and the connected substrate parts form a drift region.

[0026] The first substrate and the front structure form a combination, the second substrate and the back structure form a combination, and the two combinations are bonded together to form an IGBT device.

[0027] Compared with the related art, the manufacturing method of an IGBT device provided by the present invention has the following beneficial effects:

[0028] (1) The present invention provides a method for manufacturing an IGBT device. The manufacturing process is compatible with the existing MOS process. Both substrates can adopt conventional manufacturing processes without increasing the process difficulty and cost.

[0029] (2) Thinning the two substrates after the front and back processes can effectively avoid the problem of difficult backside processing and easy fragmentation of conventional IGBT ultra-thin wafers;

[0030] (3) The bonding process uses a plasma activation process with an annealing temperature of approximately 200 to 400°C to avoid damage to the device structure due to high temperature. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 A schematic structural diagram of a preferred embodiment of a method for manufacturing an IGBT device provided by the present invention;

[0032] Figure 2is a cross-sectional view of the first substrate after the manufacturing method according to the embodiment performs step S1;

[0033] Figure 3 is a cross-sectional view of the first substrate after the manufacturing method according to the embodiment performs step S2;

[0034] Figure 4 is a cross-sectional view of the first substrate after the manufacturing method according to the embodiment performs step S3;

[0035] Figure 5 is a cross-sectional view of the second substrate after the manufacturing method according to the embodiment performs step S4;

[0036] Figure 6 is a cross-sectional view of the second substrate after the manufacturing method according to the embodiment performs step S5;

[0037] Figure 7 is a cross-sectional view of the second substrate after the manufacturing method according to the embodiment performs step S6;

[0038] Figure 8 is a cross-sectional view of the first substrate after the manufacturing method according to the embodiment performs step S7;

[0039] Fig. 9 is a cross-sectional view of the second substrate after the manufacturing method according to the embodiment performs step S8;

[0040] Fig.10 is a cross-sectional view of the first and second substrate bonding bodies after the manufacturing method according to the embodiment performs step S9;

[0041] Numbers in the figure: 10, first substrate; 11, front structure; 12, front metal layer; 13, front passivation layer; 20, second substrate; 21, back structure; 22, back metal layer; 30, drift region; DETAILED DESCRIPTION

[0042] The present invention will be further described below in conjunction with the accompanying drawings and implementation modes.

[0043] Please refer to Figure 1 , Figure 2 , Figure 3 , Figure 4 , Figure 5 , Figure 6 , Figure 7 , Figure 8 , Fig. 9 and Fig.10 ,in, Figure 1 A schematic structural diagram of a preferred embodiment of a method for manufacturing an IGBT device provided by the present invention; Figure 2 is a cross-sectional view of the first substrate after the manufacturing method according to the embodiment performs step S1; Figure 3is a cross-sectional view of the first substrate after the manufacturing method according to the embodiment performs step S2; Figure 4 is a cross-sectional view of the first substrate after the manufacturing method according to the embodiment performs step S3; Figure 5 is a cross-sectional view of the second substrate after the manufacturing method according to the embodiment performs step S4; Figure 6 is a cross-sectional view of the second substrate after the manufacturing method according to the embodiment performs step S5; Figure 7 is a cross-sectional view of the second substrate after the manufacturing method according to the embodiment performs step S6; Figure 8 is a cross-sectional view of the first substrate after the manufacturing method according to the embodiment performs step S7; Fig. 9 is a cross-sectional view of the second substrate after the manufacturing method according to the embodiment performs step S8; Fig.10 FIG. 4 is a cross-sectional view of the first and second substrate bonding bodies after the manufacturing method according to the embodiment performs step S9 .

[0044] The first aspect of the present invention provides a method for forming an IGBT device, wherein a first substrate having an IGBT front structure and a second substrate having an IGBT back structure are bonded and connected to form an IGBT device. On the one hand, the front structure and the back structure are formed on two substrates respectively, and both substrates can adopt conventional manufacturing processes without increasing process difficulty and cost; on the other hand, the two substrates are thinned in advance before bonding, which effectively avoids the difficulty of conventional IGBT ultra-thin back process processing, reduces process difficulty, and improves the quality of IGBT devices.

[0045] In the method for forming an IGBT device provided in the embodiment of the present application, as Figure 1 As shown, the manufacturing method comprises the following steps:

[0046] S1. Provide a first substrate 10 for forming a functional area of ​​a transistor in an IGBT device. The first substrate 10 may be made of any semiconductor material that can be used to make a chip substrate.

[0047] S2, using a conventional IGBT front process to manufacture a front structure 11 in and on the first substrate 10, the surface with the front structure being the front surface of the first substrate, and the other surface away from the front surface being the back surface of the first substrate;

[0048] S3, performing a thinning process on the back side of the first substrate 10, grinding or chemical mechanical grinding from the back side of the substrate 10 to perform a thinning process on the back side of the substrate 10, and determining the grinding thickness according to needs;

[0049] S4, providing a second substrate 20, which is used to form the functional areas of the collector region and the field stop region in the IGBT device, and the second substrate 20 can be made of the same material as the first substrate 10;

[0050] S5, using a conventional IGBT back surface process to manufacture a back surface structure 21 in the second substrate 20 and on the second substrate 20, wherein the side where the back surface structure is formed is the first side of the second substrate, and the other side away from the first side is the second side of the second substrate;

[0051] S6, performing a thinning process on the second side of the second substrate 20, grinding from the second side of the substrate 20 by a grinding or chemical mechanical grinding process to thin the second side of the substrate 20, and determining the grinding thickness according to needs;

[0052] S7, plasma cleaning the back side of the first substrate 10;

[0053] S8, plasma cleaning the second side of the second substrate 20;

[0054] S9, bonding the back side of the first substrate 10 and the second side of the second substrate 20, that is, bonding the substrates made of the same material, so that the first substrate 10 and the second substrate 20 form the drift region 30 of the IGBT device.

[0055] The front structure 11 at least includes: a gate structure, a P-type base region, a P-type heavily doped region, an N-type heavily doped region (none of which are shown in the figure), a front metal layer 12, and a front passivation layer 13. The front metal layer 12 serves as the emitter electrode of the IGBT device. The gate structure can be subsequently led out through other metal layers to serve as the base of the IGBT device. Based on the structure of the existing IGBT device, the front structure 11 specifically forms a metal-oxide-semiconductor field effect transistor. However, with the development of the semiconductor field, it may also be other semiconductor device regions that can realize corresponding functions. The present invention does not impose any limitation on the front structure of the IGBT. Conventional IGBT front processes are well known to those skilled in the art and will not be described here in detail.

[0056] The back structure 21 at least includes: an N-FS layer, a P+ collector region, an N+ short-circuit region (all not shown), and a back metal layer 22. The back metal layer 22 serves as a collector electrode of the IGBT device. Based on the structure of the existing IGBT device, the back structure 21 specifically forms a FS-IGBT, an RC-IGBT and an improved structure thereof. The present invention does not impose any limitation on the back structure of the IGBT. The IGBT back process may include ion implantation or doping EPI growth, annealing process and metal process, or other required processes in the prior art. The functional area may adopt an ion implantation process to implant the required N-type impurities and P into the second substrate 20. Type impurities are removed, and then high-temperature annealing is performed to activate the N-type impurities and P-type impurities in the second substrate 20. The high-temperature annealing can be performed by high-temperature furnace tube annealing, RTA rapid annealing, laser annealing or other high-temperature annealing methods. The functional area can also be obtained by a doping EPI growth method. Epitaxial layers of N-type impurities and P-type impurities with different doping concentrations are directly grown on the second substrate 20 to form an IGBT back structure. The required N-type impurities can be arsenic, phosphorus, antimony, sulfur or selenium, and the required P-type impurities can be boron, boron fluoride or indium. The undisclosed parts and process parameters in the IGBT back process described in the present invention can be specifically referred to the prior art and will not be repeated here.

[0057] The back side of the first substrate 10 and the second side of the second substrate 20 are bonded together by a plasma activated bonding process. The bonding annealing temperature is about 200-400° C. The temperature in this range can promote the atoms on the substrate surfaces to combine with each other to form covalent bonds and achieve the required bonding strength.

[0058] The adopted process flow is divided into four stages: front process, back process, thinning process and bonding process. Two substrates of the same material are selected, and the conventional device manufacturing process is adopted. The IGBT front structure is made on the first substrate, and the IGBT back structure is made on the second substrate. The backs of the two substrates are then thinned separately, and finally the first and second substrates are bonded to form an IGBT device.

[0059] Compared with the related art, the manufacturing method of an IGBT device provided by the present invention has the following beneficial effects:

[0060] The present invention provides a method for manufacturing an IGBT device. The manufacturing process is compatible with the existing MOS process. Both substrates can adopt conventional manufacturing processes without increasing process difficulty and cost.

[0061] Thinning the two substrates after the front and back processes can effectively avoid the problem of difficult backside processing and easy fragmentation of conventional IGBT ultra-thin wafers;

[0062] The bonding process uses a plasma activation process with an annealing temperature of approximately 200 to 400°C to avoid damage to the device structure due to high temperature.

[0063] A second aspect of an embodiment of the present invention provides an IGBT device formed by the method for forming an IGBT device according to any one of the first aspects above, comprising: a first substrate 10 and a second substrate 20;

[0064] The first substrate 10 includes a front side and a back side, wherein a front side structure 11 is disposed on the front side, and a front side metal layer 12 and a front side passivation layer 13 are disposed inside the front side structure 11;

[0065] The second substrate 20 includes a first side and a second side, wherein a back surface structure 21 is disposed on the first side, and a back surface metal layer 22 is disposed inside the back surface structure 21;

[0066] The back surface of the first substrate 10 is bonded to the second side of the second substrate 20 , and the first substrate 10 and the second substrate 20 form a drift region 30 .

[0067] The first substrate 10 and the front structure 11 form a combination, and the second substrate 20 and the back structure 21 form a combination, and the two combinations are bonded together to form an IGBT device.

[0068] The IGBT device provided in the second aspect of the present application can have an overall thickness within the range of 50 to 200 μm. Thinning after completing the front and back processes can effectively avoid the difficulty of back side processing of conventional IGBT ultra-thin sheets. Since the thickness can be made thinner, the overall heat dissipation of the device is better.

[0069] The above descriptions are merely embodiments of the present invention and are not intended to limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made using the contents of the present invention specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A method for manufacturing an IGBT device, characterized in that: The following steps are involved: S1. Providing a first substrate for forming a functional area of ​​a transistor in an IGBT device. The first substrate may be made of any semiconductor material that can be used to make a chip substrate; S2. Using a conventional IGBT front process to manufacture a front structure in and on the first substrate, the surface with the front structure being the front surface of the first substrate, and the other surface away from the front surface being the back surface of the first substrate; S3, performing a thinning process on the back side of the first substrate, grinding or chemical mechanical grinding from the back side of the substrate to thin the substrate, and determining the grinding thickness according to needs; S4, providing a second substrate for forming the functional regions of the collector region and the field stop region in the IGBT device, and the second substrate may be made of the same material as the first substrate; S5, using a conventional IGBT back surface process to manufacture a back surface structure in the second substrate and on the second substrate, wherein the side where the back surface structure is formed is the first side of the second substrate, and the other side away from the first side is the second side of the second substrate; S6, performing a thinning process on the second side of the second substrate, grinding from the second side of the substrate by a grinding or chemical mechanical grinding process to thin the substrate, and determining the grinding thickness according to needs; S7, performing plasma cleaning on the back side of the first substrate; S8, plasma cleaning the second side of the second substrate; S9, bonding the back side of the first substrate and the second side of the second substrate, that is, bonding the substrates made of the same material to form an IGBT device.

2. The method for forming an IGBT device according to claim 1, characterized in that: The IGBT front side process includes the metal process of MOSFET; the IGBT back side process includes IGBT back side ion implantation, annealing process and metal process.

3. The method for forming an IGBT device according to claim 1, characterized in that: The IGBT back side process can also be produced by doped EPI growth, annealing process and metal process; the doped EPI growth is to grow epitaxial layers of N-type impurities and P-type impurities with different doping concentrations on the first side of the second substrate by doped EPI growth to form the IGBT back side structure.

4. The method for forming an IGBT device according to claim 1, characterized in that: The high temperature annealing in the IGBT back side process may be performed by high temperature furnace annealing, RTA rapid annealing, laser annealing or other high temperature annealing methods.

5. The method for forming an IGBT device according to claim 1, characterized in that: The back side of the first substrate and the second side of the second substrate are ground respectively by using a chemical mechanical grinding process to thin the substrates.

6. The method for forming an IGBT device according to claim 1, characterized in that: The thickness of the first substrate after thinning is 25 μm to 100 μm, and the thickness of the second substrate after thinning is 25 μm to 100 μm.

7. The method for forming an IGBT device according to claim 1, characterized in that: The first substrate and the second substrate are connected by a plasma activated bonding process, and the bonding annealing temperature is about 200-400°C.

8. An IGBT device formed by the method for forming an IGBT device according to any one of claims 1 to 7, characterized in that: include: a first substrate and a second substrate; The first substrate comprises a front side and a back side, wherein a front side structure is arranged on the front side, and a front side metal layer and a front side passivation layer are arranged inside the front side structure; The second substrate comprises a first side and a second side, wherein the first side is provided with a back surface structure, and a back surface metal layer is provided inside the back surface structure; The back side of the first substrate is bonded to the second side of the second substrate, and the connected substrate parts form a drift region.

9. The IGBT device according to claim 8, characterized in that: The first substrate and the front structure form a combination, the second substrate and the back structure form a combination, and the two combinations are bonded together to form an IGBT device.

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