阅读说明：本技术 一种可引入双轴应变的igbt压接式压装结构 (IGBT compression joint type press mounting structure capable of introducing double-shaft strain ) 是由 吴汪然 朱浩 王耀辉 杨光安 汤鹏宇 孙伟锋 时龙兴 于 2019-09-11 设计创作，主要内容包括：本发明提出了一种可引入双轴应变的IGBT压接式压装结构,包含发射极金属电极板、发射极凸台、银片、下钼片、IGBT芯片、上钼片和集电极金属电极板。所述的下钼片为一侧是平面一侧为球面,其中面向芯片一侧为向外突出的球面,面向发射极电极板一侧为平面；所述的上钼片一侧为平面一侧为球面,其中面向芯片一侧为向内凹陷的球面,面向集电极电极板的一侧为平面。可通过调节上钼片与下钼片球面一侧的曲率,来改变压接在其中间IGBT芯片的曲率,在不损坏IGBT芯片的前提下,可使其获得不同大小的双轴应力,其中所述的IGBT芯片集电极应面向上钼片,而发射极与源极则面向下钼片。本发明可降低器件的导通压降并提升器件的电流能力。(The invention provides an IGBT compression joint type press mounting structure capable of introducing biaxial strain, which comprises an emitting electrode metal electrode plate, an emitting electrode boss, a silver sheet, a lower molybdenum sheet, an IGBT chip, an upper molybdenum sheet and a collector electrode metal electrode plate. One side of the lower molybdenum sheet is a plane, and the other side of the lower molybdenum sheet is a spherical surface, wherein the side facing the chip is an outward protruding spherical surface, and the side facing the electrode plate of the emitter electrode is a plane; one side of the upper molybdenum sheet is a plane, and the other side of the upper molybdenum sheet is a spherical surface, wherein the side facing the chip is an inwards-concave spherical surface, and the side facing the collector electrode plate is a plane. The curvature of the IGBT chip in the middle of the upper molybdenum sheet and the lower molybdenum sheet can be changed by adjusting the curvature of one spherical side of the upper molybdenum sheet and the lower molybdenum sheet, and the IGBT chip can obtain biaxial stress with different sizes on the premise of not damaging the IGBT chip, wherein the collector of the IGBT chip is supposed to face the upper molybdenum sheet, and the emitter and the source are supposed to face the lower molybdenum sheet. The invention can reduce the conduction voltage drop of the device and improve the current capability of the device.)

1. The utility model provides a can introduce biax straying IGBT crimping formula pressure equipment structure, its characterized in that, the whole structure of crimping type IGBT pressure equipment, including emitter metal electrode board (7), emitter boss (6), silver piece (5), lower molybdenum sheet (4), IGBT chip (3), go up molybdenum sheet (2) and collector metal electrode board (1), all parts above arrange from bottom to top according to the order of emitter metal electrode board, emitter boss, silver piece, lower molybdenum sheet, IGBT chip, last molybdenum sheet and collector metal electrode board, combine together through the mode of pressure contact.

2. The IGBT compression-type press-fitting structure capable of introducing biaxial strain according to claim 1, is characterized in that the upper molybdenum sheet (2), the IGBT chip (3) and the lower molybdenum sheet (4) are embodied as follows: a lower molybdenum sheet (4) with one side being a plane and the other side being a spherical surface, wherein the side facing the chip is the spherical surface protruding outwards, and the side facing the electrode plate of the emitter electrode is the plane; the IGBT chip comprises an upper molybdenum sheet (2) with one side being a plane and the other side being a spherical surface, wherein the side facing the chip is an inward concave spherical surface, the side facing the collector electrode plate is a plane, the convex spherical surface of a lower molybdenum sheet (4) is completely matched with the concave spherical surface of the upper molybdenum sheet (2), and in addition, the curvature of the IGBT chip (3) pressed in the middle of the upper molybdenum sheet (2) and the lower molybdenum sheet (4) can be changed by adjusting the curvatures of the spherical surfaces of the upper molybdenum sheet (2) and the lower molybdenum sheet (4), so that the IGBT chip (3) obtains different biaxial stresses.

3. The IGBT compression-type press-fitting structure capable of introducing biaxial strain according to claim 1, wherein the IGBT chip (3) is embodied as follows: the collector of the IGBT chip (3) faces upward the molybdenum sheet (2), and the emitter and the source face downward the molybdenum sheet (4).

Technical Field

The invention relates to the field of IGBT packaging, in particular to an IGBT compression joint type press mounting structure capable of introducing biaxial strain.

Background

The current packaging technology of a power Insulated Gate Bipolar Transistor (IGBT) mainly includes two types, namely a compression type and a welding type. The solderability packaged IGBT is widely applied at home and abroad at present, wherein the fixation of each component in a packaging structure and interconnection bonding leads are key links of welding, so that the difference of thermal expansion coefficients of materials at two sides of a welding point is required to be within a reasonable range, and the reliability of a packaged device is improved. However, with long-term operation of the chip, thermal degradation of the solder joint occurs, which in turn causes material separation on both sides of the solder joint to a large extent, resulting in more pronounced solder-type packaging problems.

Therefore, the IGBT of the press-fit type package is receiving attention in the industry. Compared with a welding type packaged IGBT device, the IGBT device has the advantages of double-sided heat dissipation, smaller parasitic inductance, higher reliability and the like, and has greater advantages in the high-voltage high-power field. In the press-fit type package structure, the press-fit form of the IGBT has a great influence on the package reliability, the performance of the device after packaging, and other characteristics. Although many existing improvement methods for press-fitting type IGBT are provided, the improvement mainly aims at the reliability and service life of press-fitting, for example, a large-assembly IGBT press-fitting unit proposed by Zhang et al can realize series press-fitting of multi-stage IGBT devices, and realize long-term pressure maintenance and deformation adaptation through a disc spring, so that the IGBT conforms to the press-fitting standard under various working conditions, and the reliability of the devices is effectively improved. No improvement is made to the packaged core device-IGBT cell.

According to the actual engineering requirements, on the basis of the existing crimping type press-fitting IGBT, higher requirements are put forward on the crimping type press-fitting IGBT unit, namely the external structure of a device is not changed to enable the IGBT unit to have lower conduction voltage drop and more excellent current characteristics. Introducing strain into silicon can change the band structure of silicon and improve the mobility of carriers, thereby obtaining more excellent Device characteristics, for example, S.E. Thompson et al, in the article "A local nanotechnology featured-silicon" (IEEE Electron devices Letters, vol.25, pp.191-193, 2004) propose that using SiN to introduce uniaxial tensile strain in n-MOSFET, and using the lattice mismatch between SiGe source and drain and Si channel in p-MOSFET to introduce uniaxial compressive strain can greatly reduce on-resistance; bai et al, in "A65 nm logic technology creating 35nm gate lengths hs, enhanced channel strings, 8Cu interconnect layers, low-k ILD and 0.57 μm 2SRAM cell" (IEEE International Electron Devices Meeting, 2004, pp.657-660), proposed that using a second generation strain technique at the 65nm technical node increased the stress in p-MOSFET and n-MOSFET by 60% and 80%, respectively, achieving greater operating currents, and so on. At present, the existing strain process is realized in the chip manufacturing process, strain is introduced into the chip, and the strain introduction process is complex, so that the method except for process induced stress is of great significance for introducing strain into the chip and further improving the voltage and current characteristics of the device.

Disclosure of Invention

Aiming at the problems of the crimping type press-mounting IGBT, the invention provides the IGBT crimping type press-mounting structure capable of introducing biaxial strain on the basis of keeping the original press-mounting form of double-sided heat dissipation, smaller parasitic inductance and higher reliability. According to the press-fitting structure, biaxial strain can be introduced into the IGBT chip by changing the curvature of the IGBT chip, so that complicated process steps are avoided, the conduction voltage drop of the press-fitting IGBT unit can be effectively reduced, and the current characteristic of the press-fitting IGBT unit can be effectively improved.

The IGBT compression joint type press fitting structure capable of introducing biaxial strain comprises an emitter metal electrode plate, an emitter boss, a silver sheet, a lower molybdenum sheet, an IGBT chip, an upper molybdenum sheet and a collector metal electrode plate, wherein all the parts are arranged from bottom to top according to the sequence of the emitter metal electrode plate, the emitter boss, the silver sheet, the lower molybdenum sheet, the IGBT chip, the upper molybdenum sheet and the collector metal electrode plate and are combined together in a pressure contact mode.

Further, go up molybdenum piece, IGBT chip and molybdenum piece down, the concrete expression is: one side of the lower molybdenum sheet is a plane, the other side of the lower molybdenum sheet is a spherical surface, wherein one side facing the chip is the spherical surface protruding outwards, and one side facing the electrode plate of the emitter electrode is the plane; the IGBT chip comprises an upper molybdenum sheet, a lower molybdenum sheet, a collector electrode plate and a lower molybdenum sheet, wherein one side of the upper molybdenum sheet is a plane, the other side of the upper molybdenum sheet is a spherical surface, the side facing the chip is an inwards concave spherical surface, the side facing the collector electrode plate is a plane, the convex spherical surface of the lower molybdenum sheet is completely matched with the concave spherical surface of the upper molybdenum sheet, in addition, the curvature of the IGBT chip pressed in the middle of the upper molybdenum sheet and the lower molybdenum sheet can be changed by adjusting the curvature of one side of the spherical surfaces of the upper molybdenum sheet and the lower molybdenum sheet, and.

Further, the IGBT chip is embodied as follows: the collector of the IGBT chip faces upward to the molybdenum sheet, and the emitter and the source face downward to the molybdenum sheet.

Compared with the prior art, the invention has the following advantages:

according to the press-fitting structure provided by the invention, the stress of the IGBT chip in the middle of the press-fitting structure can be changed by adjusting the curvature of the concave-convex spherical surfaces of the upper molybdenum sheet and the lower molybdenum sheet, so that the performance of the IGBT chip can be adjusted. The traditional method for improving the performance of the IGBT chip mainly achieves the corresponding purpose by changing the internal structure of a device, is limited by the limit of silicon materials, and cannot achieve breakthrough progress. According to the invention, through introducing the compression joint type press mounting structure, biaxial strain is introduced into the IGBT, and on the basis of keeping the original press mounting form of double-sided heat dissipation, smaller parasitic inductance and higher reliability, the purpose of improving the device performance is achieved by changing the mobility and the energy band structure of the IGBT current carrier. In addition, since the device structure is not changed, the rest of the press-fitting structure is not changed correspondingly.

According to the press-fitting structure provided by the invention, the IGBT chip is fixed in the upper molybdenum sheet and the lower molybdenum sheet due to the concave-convex structure, so that the packaging reliability of the device is improved.

The press mounting structure provided by the invention can effectively reduce the conduction voltage drop of the IGBT chip. Therefore, under the condition of lower voltage, the IGBT chip can be started.

The press mounting structure provided by the invention can effectively improve the current capability of the device. Therefore, compared with the traditional IGBT chip, the IGBT chip can obtain stronger current capability under the same voltage condition.

Therefore, the invention can effectively reduce the conduction voltage drop of the device and effectively improve the current capability of the device on the basis of keeping the original press mounting mode, namely double-sided heat dissipation, smaller parasitic inductance and higher reliability.

Drawings

FIG. 1 is an exploded view of the press-fit arrangement of the present invention;

FIG. 2 is a schematic view of the press-fitting structure of the present invention after press-fitting;

FIG. 3 is a schematic view of the upper molybdenum sheet in the press-fitting structure according to the present invention;

FIG. 4 is a schematic structural view of a lower molybdenum sheet in the press-fit configuration of the present invention;

fig. 5 shows output characteristic curves of the IGBT chip in the conventional press-fitting structure and the press-fitting structure of the present invention under different biaxial stress conditions, with a gate voltage of 15V and an emitter voltage of 0V;

FIG. 6 shows the device turn-on voltage drop variation of the IGBT chip under different biaxial stress conditions in the conventional press-fitting structure and the press-fitting structure of the present invention, and the gate voltage is 15V (the turn-on voltage drop value is based on the collector voltage when the collector voltage of the device is gradually increased to turn on the IGBT chip, the device current reaches 0.1A, and the 0MPa data comes from the conventional press-fitting structure, and the 500MPa and 1000MPa data comes from the press-fitting structure of the present invention, where it is to be noted that the strain magnitude is not fixed, and the 500MPa and 1000MPa data are taken from the upper surface of the device);

FIG. 7 shows the variation rate of the electron mobility of the IGBT chip under different biaxial stress conditions in the conventional press mounting structure and the press mounting structure of the present invention (the stress direction is XX; and the variation rate is derived from the variation of the carrier inside the device when the output characteristic curve of the simulation device is obtained);

FIG. 8 is a longitudinal sectional view of the device for obtaining data on the rate of change of electron mobility of FIG. 7;

fig. 9 shows transfer characteristic curves of the IGBT chip in the conventional press-fitting structure and the press-fitting structure of the present invention under different biaxial stress conditions, with a collector voltage of 5V and an emitter voltage of 0V.

Detailed Description

The invention is further described below with reference to the accompanying drawings.

The invention provides an IGBT compression joint type press mounting structure capable of introducing biaxial strain, the exploded schematic diagram of which is shown in figure 1, and the structure comprises: the emitting electrode metal electrode plate 7, the emitting electrode boss 6, the silver sheet 5, the lower molybdenum sheet 4, the IGBT chip 3, the upper molybdenum sheet 2 and the collecting electrode metal electrode plate 1 are arranged from bottom to top according to the sequence of the emitting electrode metal electrode plate, the emitting electrode boss, the silver sheet, the lower molybdenum sheet, the IGBT chip, the upper molybdenum sheet and the collecting electrode metal electrode plate and are combined together in a pressure contact mode. As can be seen from fig. 1, only 16 IGBT chip units are depicted in the exploded structure of the present invention, which is only for the sake of brevity and also for ease of description, and in fact the number of IGBT chips in the press-fit structure is far more than these. As is apparent from fig. 1, the middle of the side of the lower molybdenum sheet 4 facing the IGBT chip 3 protrudes outward, the surface protruding outward is a spherical surface, the middle of the side of the upper molybdenum sheet 2 facing the IGBT chip 3 is recessed inward, the surface recessed inward is a spherical surface, the IGBT chip 3 is sandwiched between the lower molybdenum sheet 4 and the upper molybdenum sheet 2, the collector side of the IGBT chip 3 faces the upper molybdenum sheet 2, the emitter side faces the lower molybdenum sheet 4, and the size of the IGBT chip 3 is smaller than that of the upper molybdenum sheet 2 and larger than that of the lower molybdenum sheet 4, so as to prevent the IGBT chip 3 from protruding out of the upper molybdenum sheet 2 on the collector side after crimping. Fig. 2 shows the effect of all the components in fig. 1 after crimping.

Fig. 3 shows a specific structure of the upper molybdenum sheet 2, and fig. 4 shows a specific structure of the lower molybdenum sheet 4. The concave spherical surface of the upper molybdenum sheet 2 is completely matched with the convex spherical surface of the lower molybdenum sheet 4. The change of the spherical curvature of the upper molybdenum sheet 2 and the lower molybdenum sheet 4 causes the change of the pressure of the IGBT chip 3 sandwiched therebetween, which is biaxial stress. When the spherical curvatures of the upper molybdenum sheet 2 and the lower molybdenum sheet 4 are changed, the IGBT chip 3 can bear different biaxial stresses, and different device characteristics can be obtained by changing the biaxial stresses borne by the IGBT chip.

In order to verify the advantages of the invention, the device is contrastively simulated by the multi-physical field simulation software COMSOL and the semiconductor device simulation software Sentaurus TCAD, as shown in FIGS. 5 to 9. (it should be noted here that in the present embodiment, the IGBT device of 800V and 2.5A is used for simulation, the thickness of the IGBT device is 72.27 μm, and the IGBT device simulated by the present invention has universality, that is, the performance variation represents the general variation of the IGBT device after biaxial compressive stress is applied.) fig. 5 shows the output characteristic curve of the IGBT chip in the conventional press-mounting structure and the press-mounting structure of the present invention under different biaxial stress conditions, and the gate voltage is 15V and the emitter voltage is 0V, since the application of stress to the IGBT chip 3 changes the mobility of carriers, it can be seen that after biaxial stress is applied, the device is more obviously shifted to the upper left side along with the gradual increase of biaxial stress, that is, the performance of the device is more obviously improved. Fig. 6 shows the change of the turn-on voltage drop of the device when the gate voltage of the IGBT chip is 15V under different biaxial stress conditions in the conventional press-fitting structure and the press-fitting structure of the present invention (the turn-on voltage drop is based on the collector voltage when the collector voltage of the device is gradually increased to turn on the device, the collector current of the device reaches 0.1A, and the data of 0MPa is from the conventional press-fitting structure, and the data of 500MPa and 1000MPa is from the press-fitting structure of the present invention), so that fig. 6 shows this point clearly, specifically, the stresses of 500MPa and 1000MPa are obtained for the upper surface of the IGBT chip 3, respectively, because the curvatures of the IGBTs after press-fitting are different. Fig. 7 shows the change rate of the electron carrier mobility (the stress direction is XX; and the change rate comes from the change of the carrier inside the device when the output characteristic curve of the simulation device is obtained) of the IGBT chip under different biaxial stress conditions in the conventional press-fitting structure and the press-fitting structure of the present invention, so fig. 7 explains some reasons for the enhancement of the current characteristic of the device in a microscopic way, that is, the biaxial stress can improve the electron carrier mobility of the device to a certain extent. Fig. 8 shows a device longitudinal sectional line for obtaining data on the rate of change of electron mobility in fig. 7, i.e., a sectional line in which data on electron mobility is extracted in the middle of the device, starting at-72.27 μm and ending at-3 μm. Fig. 9 shows transfer characteristic curves of the IGBT chip in the conventional press-fitting structure and the press-fitting structure of the present invention under different biaxial stress conditions, where the collector voltage is 5V and the emitter voltage is 0V, and for the same reason, the current capability of the device is enhanced by applying biaxial stress to the IGBT chip 3.

Therefore, the invention can effectively reduce the conduction voltage drop of the device and effectively improve the current capability of the device on the basis of keeping the original press mounting form of double-sided heat dissipation, smaller parasitic inductance and higher reliability, so that the invention can be widely applied in the field of larger current.

It should be noted that the present invention relates to a press-fitting structure, i.e. the improvement of the structure in a broad sense, and does not relate to the specific size of the press-fitting structure, and the corresponding size can be designed according to the needs in actual production. Meanwhile, the above is only a specific embodiment of the present invention, and it is apparent to those skilled in the art that the present invention may be variously modified and changed. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.