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CN-121985741-A - SIPOS technology for improving square sheet voltage and performance

CN121985741ACN 121985741 ACN121985741 ACN 121985741ACN-121985741-A

Abstract

The invention relates to the technical field of semiconductor manufacturing, in particular to a SIPOS process for improving square sheet voltage and performance, which comprises the steps of sequentially depositing a first oxygen-doped polysilicon layer, a second oxygen-doped polysilicon layer, a silicon dioxide layer and a silicon nitride layer.

Inventors

  • GE HAO

Assignees

  • 江苏东晨电子科技有限公司

Dates

Publication Date
20260505
Application Date
20251222

Claims (10)

  1. 1. The SIPOS process for improving the square sheet voltage and the performance is characterized by comprising the following steps of: step one, taking a silicon substrate with the groove etched, and removing a silicon dioxide layer and other dielectric layers remained on the front surface of the silicon substrate by adopting a wet process; depositing a first oxygen-doped polysilicon layer on the front surface of the silicon substrate by adopting an LPCVD process; depositing a polycrystalline silicon layer on the first oxygen-doped polycrystalline silicon layer by adopting an LPCVD process; Depositing a second oxygen-doped polysilicon layer on the polysilicon layer by adopting an LPCVD process; Depositing a silicon dioxide layer on the second oxygen-doped polysilicon layer by adopting an LPCVD process; And step six, depositing a silicon nitride layer on the silicon dioxide layer by adopting an LPCVD process.
  2. 2. The SIPOS process for improving square wave voltage and performance of claim 1, wherein, In the second step, in the process of depositing the first oxygen-doped polysilicon layer, the temperature of a cavity is controlled to be 580-600 ℃, the flow rate of silane gas as a reaction gas is controlled to be 170-190ml/min, the flow rate of dinitrogen gas as a reaction gas is controlled to be 25-35ml/min, the pressure of the cavity is controlled to be 190-210mtorr, and the thickness of the final first oxygen-doped polysilicon layer is controlled to be 300-400 angstroms; In the third step, the temperature of a cavity is controlled to be 580-600 ℃ in the process of depositing the polycrystalline silicon layer, the flow rate of the reactive gas silane gas is controlled to be 140-160ml/min, the flow rate of the reactive gas nitrous oxide gas is controlled to be 0ml/min, the pressure of the cavity is controlled to be 190-210mtorr, and the thickness of the final polycrystalline silicon layer is controlled to be 18-22 angstroms; In the fourth step, in the process of depositing the second oxygen-doped polysilicon layer, the temperature of a cavity is controlled to be 580-600 ℃, the flow rate of silane gas as a reaction gas is controlled to be 140-160ml/min, the flow rate of dinitrogen gas as a reaction gas is controlled to be 28-32ml/min, the pressure of the cavity is controlled to be 190-210mtorr, and the thickness of the final second oxygen-doped polysilicon layer is controlled to be 1800-2000 angstroms; In the fifth step, in the process of depositing the silicon dioxide layer, the temperature of a cavity is controlled to be 600-620 ℃, the flow rate of the silane gas as a reaction gas is controlled to be 50-58ml/min, the flow rate of the nitrous oxide gas as a reaction gas is controlled to be 120-140ml/min, the pressure of the cavity is controlled to be 250-300 mtorr, and the thickness of the final silicon dioxide layer is controlled to be 2400-2600 angstrom; in the sixth step, in the process of depositing the silicon nitride layer, the temperature of a cavity is controlled to be 710-730 ℃, the flow rate of ammonia gas of reaction gas is controlled to be 110-130ml/min, the flow rate of dichlorosilane gas of reaction gas is controlled to be 30-36ml/min, the pressure of the cavity is controlled to be 250-300 mtorr, and the thickness of the final silicon nitride layer is controlled to be 1000-1200 angstrom.
  3. 3. The SIPOS process of claim 2, wherein in step two, the reactive gas silane gas flow is controlled to 180ml/min, the reactive gas nitrous oxide gas flow is controlled to 30ml/min, and the chamber pressure is controlled to 200mtorr.
  4. 4. The SIPOS process of claim 2, wherein the reactive gas silane gas flow rate is controlled at 150ml/min, the chamber pressure is controlled at 200mtorr, and the final polysilicon layer thickness is controlled at 20 angstroms.
  5. 5. The SIPOS process of claim 2, wherein in step four, the reactive gas silane gas flow is controlled to 150ml/min, the reactive gas nitrous oxide gas flow is controlled to 30ml/min, and the chamber pressure is controlled to 200mtorr.
  6. 6. The SIPOS process of claim 2, wherein the flow rate of the reactive gas silane is controlled to 54ml/min, the flow rate of the reactive gas nitrous oxide is controlled to 130ml/min, and the chamber pressure is controlled to 280mtorrr.
  7. 7. The SIPOS process for improving square voltage and performance according to claim 2, wherein in the sixth step, the flow rate of the reactive gas ammonia gas is controlled to 120ml/min, the flow rate of the reactive gas dichlorosilane gas is controlled to 33ml/min, and the chamber pressure is controlled to 280mtorr.
  8. 8. The SIPOS process for improving square-wave voltage and performance of claim 1, further comprising a step of densification of the silicon dioxide layer between steps five and six; After the second oxygen doped polysilicon layer is formed, the temperature of the cavity is controlled to be increased to 660-700 ℃ within 28-32min, then the temperature of the cavity is controlled to be continuously increased to 750-790 ℃ within 4-6min, the temperature is maintained for 28-32min, and finally the temperature is reduced to 620-660 ℃ within 28-32 min.
  9. 9. The SIPOS process of claim 8, wherein after the second oxygen doped polysilicon layer is formed, the chamber temperature is controlled to increase to 680 ℃ within 30 minutes, then the chamber temperature is controlled to continue to increase to 770 ℃ within 5 minutes, for 30 minutes, and finally the temperature is reduced to 640 ℃ within 30 minutes.
  10. 10. The silicon controlled thyristor is characterized in that a PN junction terminal area comprises a first oxygen doped polysilicon layer (1), a polysilicon layer (2), a second oxygen doped polysilicon layer (3), a silicon dioxide layer (4) and a silicon nitride layer (5) which are sequentially stacked, wherein the thickness of the first oxygen doped polysilicon layer (1) is 300-400 angstroms, the thickness of the polysilicon layer (2) is 18-22 angstroms, the thickness of the second oxygen doped polysilicon layer (3) is 1800-2000 angstroms, the thickness of the silicon dioxide layer (4) is 2400-2600 angstroms and the thickness of the silicon nitride layer 5 is 1000-1200 angstroms, and the silicon controlled thyristor is prepared by the SIPOS process according to any one of claims 1-9.

Description

SIPOS technology for improving square sheet voltage and performance Technical Field The invention belongs to the technical field of semiconductor manufacturing processes, and particularly relates to a SIPOS process for improving square-sheet voltage and performance. Background SIPOS (oxygen doped semi-insulating polysilicon) is a functional film widely applied to passivation of the surface of a semiconductor device, and can effectively passivate the surfaces of P-type and N-type silicon, inhibit the density of surface states and improve the pressure resistance and high-temperature stability of the device because of the neutrality and semi-insulating properties of the silicon device. In the manufacture of power devices (such as TVS, rectifier diode, silicon controlled rectifier, etc.) with high voltage and high reliability requirements, SIPOS is often used as a key component of a passivation structure of a PN junction terminal, and is usually combined with other dielectric layers (such as SiO 2、Si3N4, LTO, glass, etc.) to form a composite passivation system, so as to take into account multiple functions of electric field modulation, stress control, impurity blocking, etc. With the continuous improvement of the requirements of the terminal application on the breakdown voltage, the high-temperature leakage current and the long-term reliability of the device, the traditional SIPOS composite passivation process faces new challenges. For example, in a high-voltage square sheet product, the existing technology usually adopts a laminated structure of a polysilicon layer, an oxygen-doped polysilicon layer, an MTO (medium temperature oxide layer) and a silicon nitride layer, but in practical application, the structure is easy to have the problems of uneven voltage distribution, local electric field concentration and the like under a high electric field, so that the square sheet voltage yield is reduced, and the structure shows a double-wire breakdown characteristic under a specific bias condition, thereby influencing the consistency and the reliability of a device. Disclosure of Invention Aiming at the problems, the invention provides a SIPOS process for improving square sheet voltage and performance, by reconstructing a passivation laminated structure and accurately regulating and controlling deposition parameters of each dielectric layer, the whole passivation system presents uniform potential gradient distribution under a high electric field, so that local electric field concentration is effectively inhibited, a double-line breakdown phenomenon is eliminated, and the consistency of overall breakdown voltage is improved. The technical scheme of the invention is as follows: In a first aspect, the present invention provides a SIPOS process for improving square sheet voltage and performance, comprising the steps of: step one, taking a silicon substrate with the groove etched, and removing a silicon dioxide layer and other dielectric layers remained on the front surface of the silicon substrate by adopting a wet process; depositing a first oxygen-doped polysilicon layer on the front surface of the silicon substrate by adopting an LPCVD process; depositing a polycrystalline silicon layer on the first oxygen-doped polycrystalline silicon layer by adopting an LPCVD process; Depositing a second oxygen-doped polysilicon layer on the polysilicon layer by adopting an LPCVD process; Depositing a silicon dioxide layer on the second oxygen-doped polysilicon layer by adopting an LPCVD process; And step six, depositing a silicon nitride layer on the silicon dioxide layer by adopting an LPCVD process. Further, in the second step, in the process of depositing the process film, the temperature of the cavity is controlled to be 580 ℃ to 600 ℃, the flow rate of the silane gas as the reaction gas is controlled to be 170 ml/min to 190ml/min, the flow rate of the nitrous oxide gas as the reaction gas is controlled to be 25 ml/min to 35ml/min, the pressure of the cavity is controlled to be 190 mtorr to 210mtorr, and the thickness of the final first oxygen-doped polysilicon layer is controlled to be 300 angstrom to 400 angstrom; In the third step, the temperature of a cavity is controlled to be 580-600 ℃ in the process of depositing the polycrystalline silicon layer, the flow rate of the reactive gas silane gas is controlled to be 140-160ml/min, the flow rate of the reactive gas nitrous oxide gas is controlled to be 0ml/min, the pressure of the cavity is controlled to be 190-210mtorr, and the thickness of the final polycrystalline silicon layer is controlled to be 18-22 angstroms; In the fourth step, in the process of depositing the second oxygen-doped polysilicon layer, the temperature of a cavity is controlled to be 580-600 ℃, the flow rate of silane gas as a reaction gas is controlled to be 140-160ml/min, the flow rate of dinitrogen gas as a reaction gas is controlled to be 28-32ml/min, the pressure of the cavity is controlled to be 190-