阅读说明：本技术 一种低应力的半导体芯片 (Low-stress semiconductor chip ) 是由 阳平 于 2020-04-28 设计创作，主要内容包括：本发明涉及一种低应力的半导体芯片,包括半导体基板,半导体基板包括由多个IGBT元胞并联形成的IGBT芯片区,衬底上还设有阻止区,阻止区位于IGBT芯片区以外,阻止区内设有设有第一接触沟槽,第一接触沟槽内设有热膨胀系数大于二氧化硅热膨胀系数的金属。本发明的低应力的半导体芯片,能降低半导体芯片的面内应力和IGBT芯片区内的应力,改善硅片的翘曲度,能避免后续工艺中设备传送问题,能形成低应力的深沟槽IGBT器件。(The invention relates to a low-stress semiconductor chip which comprises a semiconductor substrate, wherein the semiconductor substrate comprises an IGBT chip area formed by connecting a plurality of IGBT unit cells in parallel, a stopping area is further arranged on the substrate and positioned outside the IGBT chip area, a first contact groove is formed in the stopping area, and metal with a thermal expansion coefficient larger than that of silicon dioxide is arranged in the first contact groove. The low-stress semiconductor chip can reduce the in-plane stress of the semiconductor chip and the stress in an IGBT chip area, improve the warping degree of a silicon wafer, avoid the problem of equipment transmission in the subsequent process and form a low-stress deep-groove IGBT device.)

1. A low-stress semiconductor chip comprising a semiconductor substrate (100) including an IGBT chip region (1) formed by a plurality of IGBT cells connected in parallel, characterized in that: the semiconductor substrate is further provided with a stopping area (2), the stopping area is located outside the IGBT chip area, a first contact groove (28) is formed in the stopping area, and metal with a thermal expansion coefficient larger than that of silicon dioxide is arranged in the first contact groove.

2. The low stress semiconductor chip of claim 1, wherein: the number of the blocking regions is even, and the plurality of blocking regions are uniformly distributed at the edge of the surface of the low-stress semiconductor chip.

3. The low stress semiconductor chip of claim 1, wherein: and a scribing groove (6) is arranged between the blocking area and the IGBT chip area.

4. The low stress semiconductor chip of claim 1, wherein: the IGBT unit cell comprises an N-type drift region (101), an N-type field termination region (21) located on the back of the N-type drift region and a collector (5) located below the N-type field termination region, a P-type collector region (22) is arranged between the N-type field termination region and the collector, an accumulation region (11) is arranged on the surface of the N-type drift region, a plurality of gate trench regions (12-A) and virtual trench regions (12-B) are further arranged in the IGBT chip region, the bottom ends of the gate trench regions are located in the N-type drift region, an insulating film (13-A) and a gate electrode (14-A) are arranged in each gate trench region, the insulating film (13-B) and a virtual gate electrode (14-B) are arranged in each virtual trench region, the insulating medium layer (17) is arranged on the surface of a semiconductor substrate, and the insulating medium layer (17) is arranged above each gate, the semiconductor device is characterized in that a P-type base region (15) is further arranged above the accumulation region, N + emitter regions (16) located on the surface of the P-type base region are arranged on the left side and the right side of the gate groove region, a second contact groove (18) or a third contact groove (19) located on the surface of the P-type base region is arranged between the gate groove region and the virtual groove region, a P + high-doping region (20) located below the second contact groove or the third contact groove is formed at the top of the P-type base region through ion implantation, emitter metal (3) connected with the N + emitter region and the virtual gate electrode is arranged on the surface of the IGBT chip region, a gate metal layer connected with the gate metal is further arranged on the surface of the IGBT chip region, and the gate metal layer and the emitter metal layer are both made of metal.

5. The low stress semiconductor chip of claim 4, wherein: and the metal filled in the first contact groove, the second contact groove and the third contact groove is aluminum-silicon alloy or aluminum-silicon-copper alloy.

6. The low stress semiconductor chip of claim 1, wherein: the depth of the third contact trench is smaller than that of the P-type base region and larger than that of the second contact trench.

7. The low stress semiconductor chip of claim 1, wherein: the third contact grooves are in strip shapes or square shapes arranged at intervals.

Technical Field

The present invention relates to semiconductor chips, and more particularly to a low stress semiconductor chip.

Background

With the development of semiconductor manufacturing technology, various chips are continuously developed toward high integration, high performance, low power consumption, light weight, and low cost. As wafer size increases and wafer thickness decreases, stress problems during wafer processing gradually develop. The stresses generated during wafer processing can cause significant warpage in wafers with larger dimensions and thinner thicknesses. In the structure of a semiconductor power device, a trench transistor is widely applied to various power devices, particularly an insulated gate bipolar transistor, due to its excellent electrical characteristics. With the improvement of the performance requirement of the device, the depth of the groove required by the device is deeper and deeper, the stress problem of the groove type polysilicon gate caused by the depth is more prominent, and the warping degree of the silicon wafer is increased due to the larger stress. When the wafer is warped, the alignment difficulty of a subsequent photoetching machine can be increased, so that the whole IGBT process flow, especially the photoetching equipment transmission difficulty in the photoetching process can be caused, and even the silicon wafer can not flow. In addition, the excessive stress may cause misalignment, which may cause a change in electrical properties of the device, an increase in the chip breaking rate, and a low chip yield.

In view of the above-mentioned drawbacks, the present designer is actively making research and innovation to create a new structure of low stress semiconductor chip, which has more industrial utility value.

Disclosure of Invention

In order to solve the above-mentioned problems, it is an object of the present invention to provide a low-stress semiconductor chip that is less likely to cause warpage.

The low-stress semiconductor chip comprises a substrate, wherein the substrate comprises an IGBT chip area formed by connecting a plurality of IGBT unit cells in parallel, the substrate is also provided with a stopping area, the stopping area is positioned outside the IGBT chip area, a first contact groove is arranged in the stopping area, and metal with the thermal expansion coefficient larger than that of silicon dioxide is arranged in the first contact groove.

Further, in the low-stress semiconductor chip of the present invention, the number of the blocking regions is even, and the plurality of blocking regions are uniformly distributed at the edge of the surface of the low-stress semiconductor chip.

Furthermore, according to the low-stress semiconductor chip, a scribing groove is arranged between the blocking area and the IGBT chip area.

Further, the low-stress semiconductor chip of the invention, the IGBT unit cell includes an N-type drift region, an N-type field termination region located on the back of the N-type drift region and a collector located below the N-type field termination region, a P-type collector region is arranged between the N-type field termination region and the collector, an accumulation region is arranged on the surface of the N-type drift region, a plurality of gate trench regions and virtual trench regions are further arranged in the IGBT chip region, the bottom ends of the gate trench regions are located in the N-type drift region, an insulating film located on the surface of the gate trench regions and a gate electrode above the insulating film are arranged in the gate trench regions, an insulating medium layer located on the surface of the substrate is arranged in the virtual trench regions and a virtual gate electrode above the insulating film, a P-type base region is further arranged above the accumulation region, N + emitter regions located on the surface of the P-type base region are arranged on the left and right sides, a second contact groove or a third contact groove located on the surface of the P-type base region is arranged between the gate groove region and the virtual groove region, a P + high doping region located below the second contact groove or the third contact groove is formed at the top of the P-type base region through ion implantation, emitter metal connected with an N + emitter region and a virtual gate electrode is arranged on the surface of the IGBT chip region, a gate metal layer connected with gate metal is further arranged on the surface of the IGBT chip region, and the gate metal layer and the emitter metal layer are both made of metal with thermal expansion coefficients larger than that of silicon dioxide.

Further, in the low-stress semiconductor chip of the present invention, the metal filled in the first contact trench, the second contact trench, and the third contact trench is aluminum-silicon alloy or aluminum-silicon-copper alloy.

Further, in the low-stress semiconductor chip of the present invention, the depth of the third contact trench is smaller than the depth of the P-type base region and larger than the depth of the second contact trench.

Further, in the low-stress semiconductor chip of the present invention, the third contact trench is in a stripe shape or a square shape arranged at intervals.

By the scheme, the invention at least has the following advantages: according to the low-stress semiconductor chip, the semiconductor substrate is provided with the plurality of stopping areas, no device structure is designed on the stopping areas, the plurality of contact grooves are only arranged in the stopping areas, the first contact grooves are formed by etching the insulating medium layer, and then the contact grooves are filled with metal with the thermal expansion coefficient larger than that of silicon dioxide. In specific implementation, 2N (N is a natural number) blocking regions may be designed on the semiconductor substrate, and the blocking regions may be in various symmetric patterns, such as circular, tetragonal, hexagonal, octagonal, and the like. The plurality of stopping areas are formed on the edge of the surface of the semiconductor chip, and the metal with the thermal expansion coefficient larger than that of silicon dioxide is arranged in the stopping areas, so that the metal generates stress in the opposite direction after being deposited at high temperature and cooled, the stress of the groove type polycrystalline silicon grid electrode is relieved, the stress among the chips of the groove type grid IGBT device is mutually isolated, and further, the tensile stress and the compressive stress generated on the whole wafer are reduced, the warping deformation of the whole wafer is improved, and the photoetching alignment precision and the flow sheet efficiency are improved.

In addition, by adding the second contact trench 18 or the third contact trench 19 between the adjacent gate trench regions and the dummy trench region, stress within a single IGBT chip can be improved. The second contact groove and the third contact groove are filled with metal (such as aluminum) with thermal expansion coefficients larger than that of silicon dioxide, so that the metal generates stress in opposite directions after being deposited at high temperature and cooled, the stress of the groove type polysilicon gate is relieved, the stress in a single IGBT chip is improved, and the performance of the IGBT device is improved. Wherein, the second contact trench 18 and the third contact trench 19 are formed by different dry etching processes respectively; the depth of the third contact trench 19 is greater than the depth of the second contact trench 18, and the depth of the third contact trench 19 is shallower than the depth of the P-type base region 15, in order to ensure that the PN junction bearing region is not pierced. The width of the third contact trench 19 and the width of the second contact trench 18 may be the same or different; the third contact groove 19 may be a unitary elongated shape or may be formed of a plurality of squares arranged at intervals; the etching depth of the third contact trench 19 and the first contact trench 28 is controlled by the etching time, and the etching depth can be set according to the requirements of device performance.

In conclusion, the low-stress semiconductor chip provided by the invention has the advantages that the problem of warping is not easy to generate in the process of processing a semiconductor power device, so that the fragment rate of a silicon wafer is reduced, and the yield of the chip is improved.

The foregoing description is only an overview of the technical solutions of the present invention, and in order to make the technical solutions of the present invention more clearly understood and to implement them in accordance with the contents of the description, the following detailed description is given with reference to the preferred embodiments of the present invention and the accompanying drawings.

Drawings

Fig. 1 is a front layout structure of a low-stress semiconductor chip in which the number of blocking regions is four, and IGBT chip regions and scribe grooves are not shown;

fig. 2 is another front side layout structure of a low stress semiconductor chip, in which the number of blocking regions is eight, and IGBT chip regions and scribe grooves are not shown;

fig. 3 is yet another front side layout configuration of a low stress semiconductor chip, wherein the number of blocking regions is four.

Fig. 4 is a plan sectional view of an IGBT chip region in which third contact trenches are stripe-shaped;

fig. 5 is another plan cross-sectional view of an IGBT chip region in which the third contact trench is square;

FIG. 6 is a cross-sectional view of an IGBT chip area;

fig. 7 is a longitudinal sectional view of an IGBT chip region.

Detailed Description

The following detailed description of embodiments of the present invention is provided in connection with the accompanying drawings and examples. The following examples are intended to illustrate the invention but are not intended to limit the scope of the invention.

Referring to fig. 1 to 7, a low stress semiconductor chip according to a preferred embodiment of the present invention includes a substrate 100, the substrate includes an IGBT chip area 1 formed by a plurality of IGBT unit cells connected in parallel, the substrate further includes a blocking area 2, the blocking area is located outside the IGBT chip area, a first contact trench 28 is formed in the blocking area, and a metal having a thermal expansion coefficient greater than that of silicon dioxide is formed in the first contact trench.

In the low-stress semiconductor chip, a plurality of stopping areas are scribed on a semiconductor substrate, no device structure is designed on the stopping areas, a plurality of contact grooves are only arranged in the stopping areas, a first contact groove 28 is formed by etching an insulating medium layer, and then metal with a thermal expansion coefficient larger than that of silicon dioxide is filled in the contact grooves. In specific implementation, 2N (N is a natural number) blocking regions may be designed on the semiconductor substrate, and the blocking regions may be in various symmetric patterns, such as circular, tetragonal, hexagonal, octagonal, and the like. The plurality of stopping areas are formed on the edge of the surface of the low-stress semiconductor chip, and the metal with the thermal expansion coefficient larger than that of silicon dioxide is arranged in the stopping areas, so that the metal generates stress in the opposite direction after being deposited and cooled at high temperature, the stress of the groove type polycrystalline silicon grid electrode is relieved, the stress among the chips of the groove type grid IGBT device is mutually isolated, the tensile stress and the compressive stress generated on the whole wafer are further reduced, the warping deformation of the whole wafer is improved, and the photoetching alignment precision and the flow sheet efficiency are improved.

Preferably, the number of the blocking regions is an even number, preferably four or eight, and the plurality of blocking regions are uniformly distributed at the edge of the surface of the low-stress semiconductor chip.

Preferably, the number of the blocking regions is four, and four first contact grooves 28 are provided in each blocking region.

Preferably, a scribing groove 6 is arranged between the blocking area and the IGBT chip area.

Preferably, the IGBT unit cell comprises an N-type drift region 101, an N-type field termination region 21 located on the back of the N-type drift region, and a collector 5 located below the N-type field termination region, a P-type collector region 22 is arranged between the N-type field termination region and the collector, an accumulation region 11 is arranged on the surface of the N-type drift region, a plurality of gate trench regions 12-A and virtual trench regions 12-B are further arranged in the IGBT chip region, the bottom ends of the gate trench regions are located in the N-type drift region, an insulating film 13-A and a gate electrode 14-A are arranged in each gate trench region, the insulating film 13-B and the virtual gate electrode 14-B are arranged in each virtual trench region, the insulating medium layer 17 is arranged on the surface of the substrate, and a P-type base region 15 is further arranged above the accumulation region, the IGBT chip area is characterized in that N + emitter regions 16 located on the surface of the P-type base region are arranged on the left side and the right side of the gate groove region, a second contact groove 18 or a third contact groove 19 located on the surface of the P-type base region is arranged between the gate groove region and the virtual groove region, a P + high-doping region 20 located below the second contact groove or the third contact groove is formed at the top of the P-type base region through ion implantation, emitter metal 3 connected with the N + emitter region and the virtual gate electrode is arranged on the surface of the IGBT chip region, a gate metal layer (not shown in the figure) connected with gate metal is further arranged on the surface of the IGBT chip region, and the gate metal layer and the emitter metal layer are both made of metal with thermal expansion coefficients larger.

By adding the second contact trench 18 or the third contact trench 19 between the adjacent gate trench regions and the dummy trench region, the stress within a single IGBT chip can be improved. The second contact groove and the third contact groove are filled with metal with thermal expansion coefficient larger than that of silicon dioxide, such as aluminum, so that the metal generates stress in opposite directions after being deposited at high temperature and cooled, the stress of the groove type polysilicon gate is relieved, the stress in a single IGBT chip is improved, and the performance of the IGBT device is improved. Wherein, the second contact trench 18 and the third contact trench 19 are formed by different dry etching processes respectively; the depth of the third contact trench 19 is greater than the depth of the second contact trench 18, and the depth of the third contact trench 19 is shallower than the depth of the P-type base region 15, in order to ensure that the PN junction bearing region is not pierced. The width of the third contact trench 19 and the width of the second contact trench 18 may be the same or different; the third contact groove 19 may be a unitary elongated shape or may be formed of a plurality of squares arranged at intervals; the etching depth of the third contact trench 19 and the first contact trench 28 is controlled by the etching time, and the etching depth can be set according to the requirements of device performance.

Preferably, the metal filled in the first contact trench, the second contact trench, and the third contact trench is aluminum-silicon alloy or aluminum-silicon-copper alloy.

Preferably, the depth of the third contact trench is smaller than the depth of the P-type base region and larger than the depth of the second contact trench.

Preferably, the third contact trench is a stripe shape or a square shape arranged at intervals.

The manufacturing method of the low-stress semiconductor chip of the invention comprises the following steps:

s1, an N-type monocrystalline silicon material or an N-type epitaxial silicon material is used as a substrate material and serves as an N-type drift region of the power device.

S2. neglecting the formation process of the termination region, an accumulation region 11 is formed in the device active region of the semiconductor substrate 100 by ion implantation and high temperature drive-in.

S3. in the active areaThe gate trench region 12-a and the dummy trench region 12-B are formed by photolithography and reactive ion etching. A gate groove region 12-A and a virtual groove region 12-B are formed in an IGBT chip region, and the gate groove region 12-A and the virtual groove region 12-B can be formed according to a certain proportion of 1: n is set. The groove regions may be arranged at equal intervals or at unequal intervals. Specifically, the semiconductor substrate 100 is grown on the surface with a thickness ofThe silicon dioxide barrier layer is used as a barrier layer for etching the groove; etching the silicon dioxide barrier layer by using the photoetching mask to form a silicon dioxide barrier layer pattern; then removing the photoresist; etching the silicon substrate by taking the silicon dioxide barrier layer pattern as a mask, namely deeply digging a plurality of grooves to form a gate groove area 12-A and a virtual groove area 12-B; and removing the residual silicon dioxide barrier layer by wet etching.

S4, growing a layer of insulating films 13-A and 13-B with higher compactness on the inner wall of each groove area in the active area through high-temperature oxidation. Specifically, a sacrificial oxide layer is grown on the inner wall of each groove area through high-temperature oxidation, and then the sacrificial oxide layer is corroded by a wet method, so that the insulating film is smooth and flat; and growing an insulating film on the inner wall of each groove region through high-temperature oxidation. Wherein the thickness of the insulating film isThe operation steps are to reduce crystal defects and impurities, so that an insulating film with better compactness is grown to be used as a gate oxide film of an MOS structure;

and S5, depositing a layer of polycrystalline silicon on the surface of the semiconductor substrate 100, and covering the groove and the surface of the substrate by using the polycrystalline silicon. And then doping to form N-type polysilicon. Specifically, polysilicon is deposited on the surface of the semiconductor substrate 100 by a high-temperature furnace tube and is subjected to in-situ doping to form N-type polysilicon, the thickness of the polysilicon is 0.5-2um, and the concentration of the polysilicon is 1E20cm^-3(ii) a And then activating the polysilicon at high temperature of 950 ℃ for 30 minutes.

S6, performing reactive ion etching on the polycrystalline silicon on the surface of the semiconductor substrate 100, wherein the etching thickness is 0.5-2um, and only the polycrystalline silicon in each groove area, on the PAD (PAD area) of the gate electrode and on the BUS (BUS) channel of the gate electrode is reserved. Thereby forming a gate electrode 14-a and a dummy gate electrode 14-B. Wherein gate electrode 14-a is formed in gate trench region 12-a and dummy gate electrode 14-B is formed in dummy trench region 12-B.

S7, forming a P-type base region 15 in the active region; specifically, ion implantation is performed in the gap between the gate trench region 12-a and the dummy trench region 12-B; then, a high-temperature drive-in is performed for a long time, thereby forming the P-type base region 15 in the IGBT chip region. Wherein the concentration of the implanted boron ions is 2E13-3E13 cm^-2The implantation energy is 80-120 Kev.

And S8, forming an N + emitter region 16 on the upper surface of the P-type base region 15 in the active region of the IGBT device through ion implantation and high-temperature drive-in. Specifically, a mask which is not used for carrying out ion implantation on two sides of the virtual groove region but is only used for carrying out ion implantation on two sides of the grid groove region is used, and an implantation window of the N + emission region is formed by utilizing a photoetching mask; and injecting high-energy arsenic ions into the injection window of the N + emitter region and carrying out high-temperature well pushing, so that an N + emitter region 16 is formed on the upper surfaces of the P-type base regions on the two sides of the gate trench region in the IGBT region.

S9, depositing an insulating medium layer 17 on the surface of the semiconductor substrate, and reflowing to flatten the insulating medium layer. The thickness of the insulating medium layer is 1-1.5 um; the insulating medium layer can be formed by stacking a plurality of layers of insulating media;

s10, etching the insulating medium layer 17 in the gap between the grid groove area and the virtual groove area and etching the semiconductor substrate downwards to form a second contact groove 18.

And S11, etching the insulating medium layer 17 in the gap between the gate groove area and the virtual groove area and etching the semiconductor substrate downwards, so that a third contact groove 19 is formed in the IGBT chip area 1, and a first contact groove 28 is formed in the stopping area 2.

And S12, injecting boron ions into the contact grooves 18 and 19 to form a P + high-doping area 20, namely a contact area.

And S13, depositing emitter metal on the surface of the device and forming an emitter electrode 3 and a gate metal layer 4 through etching. Specifically, a metal film with the thickness of 1-5um is deposited on the surface of the device; then forming an emitter electrode 3 and a gate metal layer 4 by etching; the emitter electrode 3 and the gate metal layer 4 are isolated from each other by an insulating dielectric layer 17. The metal is aluminum/silicon alloy or aluminum/silicon/copper alloy or other materials, the thickness is 1-5um, and the high-doped silicon and the metal form ohmic contact through heating alloying, so that the contact resistance is reduced.

S14, after the front side of the power device is metalized, turning over the chip and thinning the back side.

S15, forming an N-type field termination region 21 on the back surface of the semiconductor substrate through phosphorus ion implantation and a high-temperature well pushing process; the doping concentration of the N-type field stop region 21 is 1E15-1E17 cm^-3The junction depth is 1-3um, so that the compromise characteristic of the IGBT can be improved, and the current trailing time when the IGBT is turned off is reduced.

S16, forming a back P-type collector region 22 on the back of the semiconductor substrate through boron ion implantation and a high-temperature well-pushing process; wherein the doping concentration of the P-type collector region 22 is 1E18-5E19 cm^-3The junction depth is 0.5-1um, so as to control the hole emission efficiency.

And S17, metalizing the back surface of the power device to form a back collector 5.

It will be evident to those skilled in the art that the invention is not limited to the details of the foregoing illustrative embodiments, and that the present invention may be embodied in other specific forms without departing from the spirit or essential attributes thereof. The present embodiments are, therefore, to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description.

In addition, the above description is only a preferred embodiment of the present invention, and is not intended to limit the present invention, it should be noted that, for those skilled in the art, several modifications and variations can be made without departing from the technical principle of the present invention, and these modifications and variations should also be regarded as the protection scope of the present invention. Also, it should be understood that although the present description refers to embodiments, not every embodiment may contain only a single embodiment, and such description is for clarity only, and those skilled in the art should integrate the description, and the embodiments may be combined as appropriate to form other embodiments understood by those skilled in the art.