WO2018040563A1 - Novel polycrystalline silicon thin-film zener diode and fabrication method therefor - Google Patents

Abstract

Disclosed are a polycrystalline silicon thin-film Zener diode and a fabrication method therefor, comprising: a substrate (100), and a passivation layer A (200) and a polycrystalline silicon thin film (300) sequentially grown on the substrate (100), wherein an N-type doped region (301) is formed in a part of the polycrystalline silicon thin film (300), and a P-type doped region (302) is formed in another part of the polycrystalline silicon thin film (300); a passivation layer B (400), located in an upper surface region of the polycrystalline silicon thin film (300); an electrode (500) on the N-type doped region (301), the electrode (500) being located above the N-type doped region (301) and above a portion of the passivation layer (401); an electrode (600) on the P-type doped region (302), the electrode (600) being located above the P-type doped region (302) and above a portion of the passivation layer (402). Activating N-type dopants and P-type dopants by using laser annealing may improve the activation processes in a traditional high-temperature furnace, while featuring a short time and high flexibility.

Description

Novel polysilicon film Zener diode and manufacturing method thereof Technical field

The invention relates to the field of manufacturing semiconductor devices, in particular to a novel polysilicon film Zener diode and a manufacturing method thereof.

Background technique

The Zener diode acts as a reference voltage source in a regulated power supply or as a protection diode in an overvoltage protection circuit due to its regulation.

After the conventional Zener diode is doped, the N-type and P-type doped regions are obtained by annealing in a high-temperature furnace in a vacuum environment. In combination with the fabrication process, production cost, and integration of power devices such as GaN, conventional high temperature furnace annealed Zener diodes have the following disadvantages:

(1) Heating and annealing of high temperature furnace, the lattice damage repair rate is low, the electric activation rate is low, and the impurities are also changed due to thermal diffusion.

(2) Heating and annealing of high-temperature furnace requires high-temperature furnace annealing in a vacuum environment for a long time. The environment is relatively complicated and time-consuming is long. In terms of production, it is not conducive to the increase of output.

(3) The treatment of the high temperature furnace easily causes the deformation of the silicon wafer and increases the difficulty of the subsequent processing.

(4) If integrated with GaN and other power devices to achieve voltage regulation, the high temperature annealing process can only be performed before metallization of power devices such as GaN, which limits the integration process.

Summary of the invention

In view of the above problems, the present invention provides a novel polysilicon film Zener diode and a fabrication method thereof, the main feature of which is to activate the N-type dopant and the P-type dopant by laser annealing, thereby improving the activation of the conventional high-temperature furnace. Process problems, short time and high flexibility can effectively solve problems in the background art.

In order to achieve the above object, the technical solution adopted by the present invention is as follows: A novel polysilicon film Zener diode, comprising:

a substrate and a passivation layer A and a polysilicon film sequentially grown on the substrate; an N-type doped region formed in a portion of the polysilicon film; and a P-type doped region formed in another portion of the polysilicon film;

a passivation layer B, the passivation layer being located in an upper surface region of the polysilicon film;

An N-region electrode on the N-type doped region, the electrode being above the N-type doped region and above the portion of the passivation layer A;

A P-region electrode on the P-type doped region, the electrode being above the P-type doped region and above the portion of the passivation layer B.

Preferably, the material of the substrate is Si material; the material of the passivation layer A is SiO ₂ , Si ₃ N ₄ , AlN, Al ₂ O ₃ , MgO, Sc ₂ O ₃ , TiO ₂ , HfO ₂ , BCB, ZrO ₂ , Ta ₂ O ₅ and La ₂ O ₃ ; the polysilicon film is an in-situ doped or intrinsic polysilicon film; the logarithm of the PN junction is 1, or any integer greater than one.

Preferably, the material of the N-region electrode is Si, Ti, Al, Ni, Mo, Pt, Pd, Au, W, TiW, TiN and any combination therebetween; the material of the P-region electrode is Si, Ti, Al, Ni, Mo, Pt, Pd, Au, W, TiW, TiN and any combination therebetween.

In addition, the present invention also designs a novel polysilicon film Zener diode manufacturing method, including the following steps:

S1, a passivation layer A is grown on the substrate, and a polysilicon film is formed on the passivation layer A;

S2, forming an N-type doped region in a partial region of the polysilicon film;

S3, forming a P-type doped region in another portion of the polysilicon film region;

S4, forming a passivation layer B over the polysilicon film region;

S5, forming an N-region electrode in the N-type doping region;

S6, forming a P-region electrode in the P-type doping region.

Preferably, the material of the substrate is Si, diamond or SiC material; the polysilicon film is grown in a high temperature CVD mode; the polysilicon film has a thickness of 10 nm to 1 μm; and the dopant concentration of the N-doped region 10 ¹⁷ -10 ²² /cm ^-3 ; the activation process of the dopant of the N-type doping region is laser annealing; the dopant concentration of the P-type doping region is 10 ¹⁷ -10 ²² /cm ^{- 3} .

Preferably, the material of the passivation layer B above the polysilicon film is SiO ₂ , Si ₃ N ₄ , AlN, Al ₂ O ₃ , MgO, Sc2O3, TiO ₂ , HfO ₂ , BCB, ZrO ₂ , Ta ₂ O ₅ and La ₂ O ₃ .

Preferably, the N-type doped region electrode and the P-type doped region electrode are prepared by sputtering or evaporation; the N-type doped region is doped by in-situ doping or implantation; The dopant of the doped region is an impurity such as phosphorus or arsenic; and the dopant of the N-type doping region is doped by in-situ doping or implantation.

Preferably, the method further comprises the step of forming a mesa on the same wafer by etching to isolate the other novel polysilicon film Zener diodes.

Preferably, the activation mode of the dopant of the P-type doping region is laser annealing activation; the P-type doping region is doped by in-situ doping or implant doping.

Preferably, the dopant of the P-type doping region is boron or other impurity source.

The beneficial effects of the invention:

(1) Using the laser annealing process to improve the damage repair rate and the electrical activation rate in the conventional process;

(2) Using the laser annealing process, the annealing time is short, the speed is fast, and the efficiency is high, which is beneficial to the reduction of the device preparation cost;

(3) The laser annealing process is adopted, no vacuum environment is needed in the annealing process, and it can be carried out in the atmosphere, and the conditions are simplified;

(4) Omit the high temperature furnace treatment to avoid deformation of the silicon wafer, and at the same time, the preparation of the Zener diode can be compatible with the preparation process of power devices such as GaN, realize on-chip integration, and has wide application prospects.

DRAWINGS

In order to make the objects, contents and advantages of the present invention more comprehensible, the detailed description will

1 is a schematic view showing a structure of a novel polysilicon film Zener diode according to an embodiment of the present invention;

2 to 13 are flow charts of a preparation process according to an embodiment (taking implant doping as an example, and the number of PN junctions is greater than 1).

The labels in the figure are:

100-substrate; 200-passivation layer A; 300-polysilicon film; 400-passivation layer B;

500-N zone electrode; 600-P zone electrode; 301-N type doped zone; 302-P type doped zone;

401-partial passivation layer A; 402-partial passivation layer B.

detailed description

It should be noted that the embodiments in the present application and the features in the embodiments may be combined with each other without conflict. The invention will be described in detail below with reference to the drawings in conjunction with the embodiments.

In order to make the objects, technical solutions and advantages of the present invention more comprehensible, the present invention will be further described in detail below with reference to the embodiments. It is understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

implementation plan:

As shown in FIG. 2, a passivation layer A200 is deposited on the substrate 100. The passivation layer A200 is SiO ₂ , Si ₃ N ₄ , AlN, Al ₂ O ₃ , MgO, Sc ₂ O ₃ , TiO ₂ , HfO ₂ , BCB, ZrO ₂ , Ta ₂ O ₅ and La ₂ O ₃ . The passivation layer A200 is deposited by sputtering or chemical vapor deposition or the like. The passivation layer A200 has a thickness of 20 nm to 1 μm;

As shown in FIG. 2, a polysilicon film 300 is deposited on the passivation layer A200 by a process such as CVD. 20 nm-1 μm of the polysilicon film 300;

As shown in FIG. 3, a sacrificial layer 305 is deposited on the polysilicon thin film layer 300. The sacrificial layer 305 is SiO ₂ , Si ₃ N ₄ , AlN, Al ₂ O ₃ , MgO, Sc ₂ O ₃ , TiO ₂ , HfO ₂ , BCB, ZrO ₂ , Ta ₂ O ₅ and La ₂ O ₃ . The passivation layer B400 is deposited by sputtering or chemical vapor deposition or the like. The thickness of the sacrificial layer 305 is 5 nm - 100 nm

As shown in FIG. 4, N-doping is performed, and the implanted impurity source is phosphorus or arsenic, and the implantation dose is E13 to E18/cm3, and the implantation energy is 20 to 400 keV;

As shown in FIG. 5, the sacrificial layer is removed by an etch etching process and activated by a laser annealing process.

As shown in FIG. 6, a portion of the polysilicon film region is etched by photolithography, plasma dry etching or wet etching to form a mesa 304 to achieve isolation between the devices.

As shown in FIG. 7, a P-type implantation sacrificial layer 305 is deposited in the polysilicon film 300 region, and the sacrificial layer 305 is SiO ₂ , Si ₃ N ₄ , AlN, Al ₂ O ₃ , MgO, Sc ₂ O ₃ , TiO ₂ , HfO. ₂ , BCB, ZrO ₂ , Ta ₂ O ₅ and La ₂ O ₃ and the like. The sacrificial layer 305 is deposited by sputtering or chemical vapor deposition or the like. The sacrificial layer 305 has a thickness of 20 nm to 1 μm.

As shown in FIG. 8, the P-type injecting window 306 is implanted by a process such as photolithography, dry etching, or wet etching.

As shown in FIG. 9, N-doping implantation is performed, and the implanted impurity source is boron or gallium, and the implantation dose is E13 to E18/cm3, and the implantation energy is 20 to 400 keV;

As shown in FIG. 10, the sacrificial layer is removed by an etch etching process and activated by a laser annealing process.

As shown in FIG. 11, a passivation layer B400 is deposited. The passivation layer B400 is SiO ₂ , Si ₃ N ₄ , AlN, Al ₂ O ₃ , MgO, Sc ₂ O ₃ , TiO ₂ , HfO ₂ , BCB, ZrO ₂ , Ta ₂ O ₅ and La ₂ O ₃ . The passivation layer B400 is deposited by sputtering or chemical vapor deposition or the like. The passivation layer B400 has a thickness of 20 nm to 1 μm;

As shown in FIG. 12, a pattern partial passivation layer A 401 and a partial passivation layer B 402 are formed on the passivation layer B400 by photolithography, plasma dry etching or wet etching.

As shown in FIG. 13, the N-region electrode 500 and the P-region electrode 600 are separately formed in the partial passivation layer A 401 and the partial passivation layer B 402 by photolithography, electron beam evaporation or sputtering techniques, respectively. The metals of the N-region electrode 500 and the P-region electrode 600 are Ti, Al, Ni, Mo, Pt, Pd, Au, W, TiW, TiN, and any combination therebetween. The N-region electrode 500 and the P-region electrode 600 form an ohmic contact with the N-type doping region 301 and the P-type doping region 302, respectively.

The above is only the preferred embodiment of the present invention, and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection of the present invention. Within the scope.

Claims (10)

A polysilicon film Zener diode, comprising: a substrate (100) and a passivation layer A (200) and a polysilicon film (300) sequentially grown on the substrate (100); an N-type doped region (301) formed in a partial region of the polysilicon film; a portion of the formed P-type doped region (302); a passivation layer B (400), the passivation layer being located in an upper surface region of the polysilicon film (300); An N-region electrode (500) on the N-type doped region (301), the electrode being above the N-type doped region (301) and above the portion of the passivation layer A (401); A P-region electrode (600) on the P-type doped region (302) is above the P-type doped region (302) and above the portion of the passivation layer B (402). The polysilicon thin film Zener diode according to claim 1, wherein the material of the substrate (100) is Si material; the material of the passivation layer A (200) is SiO ₂ , Si ₃ N ₄ , AlN, Al ₂ O ₃ , MgO, Sc ₂ O ₃ , TiO ₂ , HfO ₂ , BCB, ZrO ₂ , Ta ₂ O ₅ and La ₂ O ₃ ; the polysilicon film (300) is doped in situ or Intrinsic polysilicon film; the logarithm of the PN junction is 1, or any integer greater than one. The polysilicon thin film Zener diode according to claim 1, wherein the material of the N-region electrode (500) is Si, Ti, Al, Ni, Mo, Pt, Pd, Au, W, TiW, TiN and any combination therebetween; the material of the P-region electrode (600) is Si, Ti, Al, Ni, Mo, Pt, Pd, Au, W, TiW, TiN and any combination therebetween. A method for fabricating a polysilicon film Zener diode, comprising the steps of: S1, a passivation layer A (200) is grown on the substrate (100), and a polysilicon film (300) is formed on the passivation layer A (200); S2, forming an N-type doped region (301) in a partial region of the polysilicon film (300); S3, forming a P-type doped region (302) in another portion of the polysilicon film region (300); S4, forming a passivation layer B (400) above the polysilicon film region (300); S5, forming an N-region electrode (500) in the N-type doping region (301); S6, forming a P-region electrode (600) in the P-type doping region (302). The manufacturing method according to claim 4, wherein the material of the substrate (100) is Si, diamond or SiC material; the polysilicon film (300) is grown by a high temperature CVD method; 300) a film thickness of 10 nm to 1 μm; a dopant concentration of the N-type doping region (301) of 10 ¹⁷ -10 ²² /cm ^-3 ; a dopant of the N-type doping region (301) The activation process is laser annealing; the dopant concentration of the P-type doping region (302) is 10 ¹⁷ -10 ²² /cm ^-3 . The manufacturing method according to claim 4, wherein the material of the passivation layer B (400) above the polysilicon film is SiO ₂ , Si ₃ N ₄ , AlN, Al ₂ O ₃ , MgO, Sc ₂ O ₃ , TiO ₂ , HfO ₂ , BCB, ZrO ₂ , Ta ₂ O ₅ and La ₂ O ₃ . The manufacturing method according to claim 4, wherein the N-type doping region electrode (601) and the P-type doping region electrode (602) are prepared by sputtering or evaporation; the N-type doping The region (301) is doped by in-situ doping or implantation; the dopant of the N-type doping region (301) is an impurity such as phosphorus or arsenic; and the doping of the N-type doping region (301) The dopant is doped by in-situ doping or implantation. The fabricating method according to claim 4, further comprising the step of isolating the mesa (304) on the same wafer from the other novel polysilicon thin film Zener diodes by etching. The fabrication method according to claim 4, wherein the activation mode of the dopant of the P-type doping region (302) is laser annealing activation; the P-type doping region (302) is doped by in-situ Doping is carried out by means of impurities or implant doping. The method according to claim 4, wherein the dopant of the P-type doping region (302) is boron or other impurity source.

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