A radiation-resistant bipolar device with STI ion implantation and its fabrication method

Abstract

This invention discloses a radiation-hardened bipolar device with STI ion implantation and its fabrication method, belonging to the field of radiation hardening technology for bipolar devices. In the radiation hardening method provided by this invention, after STI etching, STI filling, and STI CMP in the bipolar device fabrication process, ion implantation is performed on the STI structure. The implanted ions are fluoride ions, chloride ions, bromide ions, iodide ions, or arsenic ions. By changing the type and concentration of ions in the STI oxide layer through ion implantation, the influence of trapped positive charges and interface states in the STI oxide after total dose irradiation can be significantly reduced, thereby improving the radiation resistance of the bipolar device.

Description

Technical Field

[0001] This invention belongs to the field of radiation hardening technology for bipolar devices, and specifically relates to a radiation-resistant bipolar device with STI ion implantation and its preparation method. Background Technology

[0002] The space radiation environment can cause total dose effect (TID) in bipolar devices, which is directly manifested as excess base current ΔI. B As the total dose irradiation increases, the gain coefficient β decreases. This is mainly due to the damage caused by the total dose irradiation to the SiO2 material in the bipolar device structure. The total dose effect generates electron-hole pairs in SiO2. The holes have a relatively slow migration rate. Apart from some recombination with electrons, the remaining holes are gradually captured by defects in the SiO2 layer as they move towards the SiO2 / Si interface, forming an oxide layer to fix the charge. In addition, the holes react with the Si-H bonds in the SiO2 layer to replace H atoms. + Ultimately H + It moves to the SiO2 / Si interface and reacts with the interface Si-H bonds to generate an interface state.

[0003] In the prior art, common methods for radiation hardening of bipolar devices mainly include reducing the base region width, increasing the surface doping concentration of the base region, reducing the surface oxide layer thickness of the base region, and reducing the emitter perimeter-to-area ratio. These hardening methods seriously affect the normal characteristics of bipolar devices. In order to ensure the stability of the normal characteristics of bipolar devices, a large number of process parameters need to be redeveloped.

[0004] Research has found that by altering the ion types and concentrations in the STI (Shallow Trench Isolation) oxide layer of bipolar devices through ion implantation, the fixed charge and number of interface states in the oxide layer caused by irradiation within the STI can be reduced, thereby improving the bipolar device's resistance to total dose irradiation. Summary of the Invention

[0005] To address the problem that the reduced radiation resistance (decreased current gain) of bipolar devices is caused by the trapping of positive charges and the influence of interface states in the STI oxide layer above the EB junction, this invention proposes an STI ion-implanted radiation-resistant bipolar device and its fabrication method.

[0006] The technical steps to achieve the objective of this invention are as follows: A radiation-resistant bipolar device with STI ion implantation includes, from bottom to top, a first conductivity type substrate, a second conductivity type buried layer, and a second conductivity type collector deep well region. A second conductivity type collector well region is disposed above the periphery of the second conductivity type collector well region. A second conductivity type collector implantation region is disposed above the second conductivity type collector well region. A first conductivity type base deep well region is disposed above the interior of the second conductivity type collector deep well region. A first conductivity type base well region is disposed above the periphery of the first conductivity type base deep well region. A first conductivity type base well region is disposed above the first conductivity type base well region. A base implantation region of the first conductivity type is provided, and an emitter well region of the second conductivity type is provided above the base deep well region of the first conductivity type. An emitter implantation region of the second conductivity type is provided above the emitter well region of the second conductivity type. An ion implantation STI isolation structure is provided between the emitter implantation region of the second conductivity type and the base implantation region of the first conductivity type and above the base deep well region of the first conductivity type. An ion implantation STI isolation structure is provided between the base implantation region of the first conductivity type and the collector implantation region of the second conductivity type. An ion implantation STI isolation structure is provided outside the collector implantation region of the second conductivity type and above the periphery of the collector deep well region of the second conductivity type.

[0007] A method for fabricating the above-mentioned STI ion-implanted radiation-resistant bipolar device includes the following steps:

[0008] (i) A first conductivity type substrate silicon wafer is provided, and photolithography and doping ion implantation are performed on its upper surface, followed by annealing to form a second conductivity type buried layer; photolithography and doping ion implantation are performed on the upper surface of the second conductivity type buried layer, followed by annealing to form a second conductivity type collector deep well region; photolithography and doping ion implantation are performed on the upper surface of the second conductivity type collector deep well region to form a first conductivity type base deep well region.

[0009] (ii) An oxide layer and a SiN layer are grown on the upper surface of the collector deep well region of the second conductivity type and the base deep well region of the first conductivity type, and active region photolithography and STI etching are performed to form STI trenches.

[0010] (iii) Deposit SiO2 or a stacked structure in the STI trench to ensure electrode isolation, and then perform chemical mechanical polishing to form the STI shallow trench isolation area.

[0011] (iv) Ion implantation is performed on the filling material of the STI shallow trench isolation zone. The implanted ions are fluoride ions, chloride ions, bromide ions, iodide ions or arsenic ions, and then annealing is performed.

[0012] (v) Photolithography and doped ion implantation are performed on the upper surfaces of the second conductivity type collector deep well region and the first conductivity type base deep well region to form the second conductivity type collector well region, the second conductivity type collector implantation region, the first conductivity type base well region, the first conductivity type base implantation region, the second conductivity type emitter well region, and the second conductivity type emitter implantation region, thus forming a complete radiation-hardened bipolar device structure.

[0013] Compared with the prior art, the significant advantages of the present invention are as follows: The reinforcement method proposed in this invention is based on the existing bipolar device fabrication process. By ion implantation into the STI filling material, the types and concentrations of ions in the STI filling material are changed, so that under the same irradiation dose conditions, the degree of current gain damage is reduced, and the influence of oxide trapping positive charge and interface state is reduced, so as to improve the bipolar device's resistance to total dose irradiation. Attached Figure Description

[0014] Figure 1 This is a schematic cross-sectional view of the structure formed by photolithography and doping ion implantation on a silicon wafer 1 of the first conductivity type, followed by annealing to form a buried layer 2 of the second conductivity type; photolithography and ion implantation on the upper surface of the buried layer 2 of the second conductivity type, followed by annealing to form a collector deep well region 3 of the second conductivity type; and photolithography and ion implantation on the upper surface of the collector deep well region 3 of the second conductivity type, followed by annealing to form a base deep well region 6 of the first conductivity type.

[0015] Figure 2 This is a schematic diagram of the structure after growing an oxide layer and depositing a SiN layer on the upper surfaces of the collector deep well region 3 (second conductivity type) and the base deep well region 6 (first conductivity type), performing active region photolithography and STI etching to form an STI trench.

[0016] Figure 3 This is a schematic diagram of the cross-section of the structure after depositing SiO2 or various stacked structures in the STI trench, ensuring electrode isolation, and then performing chemical mechanical polishing to form the STI shallow trench isolation zone 11.

[0017] Figure 4 This is a schematic diagram of photolithography on the device surface, where photoresist is used to block most of the surface, exposing only the STI trench area, and then ion implantation is performed on the STI trench.

[0018] Figure 5 This is a schematic diagram of the complete radiation-hardened bipolar device structure.

[0019] Labeling explanations: 1: Substrate of first conductivity type, 2: Buried layer of second conductivity type, 3: Collector deep well region of second conductivity type, 4: Collector well region of second conductivity type, 5: Collector implantation region of second conductivity type, 6: Base deep well region of first conductivity type, 7: Base well region of first conductivity type, 8: Base implantation region of first conductivity type, 9: Emitter well region of second conductivity type, 10: Emitter implantation region of second conductivity type, 11: Ion implanted STI isolation structure. Detailed Implementation

[0020] The following detailed description, in conjunction with the accompanying drawings and specific embodiments, provides a method for strengthening the total dose radiation resistance of a SiN-interlayer STI-isolated transistor according to the present invention. The advantages and features of the present invention will become clearer from the following description and claims. It should be noted that the drawings are all in a very simplified form and use non-precise proportions, and are only used to facilitate and clarify the illustration of the embodiments of the present invention.

[0021] This invention proposes a radiation-resistant bipolar device with STI ion implantation, comprising, from bottom to top, a first conductivity type substrate 1, a second conductivity type buried layer 2, and a second conductivity type collector deep well region 3. A second conductivity type collector well region 4 is disposed above the periphery of the second conductivity type collector well region 3. A second conductivity type collector implantation region 5 is disposed above the second conductivity type collector well region 4. A first conductivity type base deep well region 6 is disposed above the interior of the second conductivity type collector deep well region 3. A first conductivity type base well region 7 is disposed above the periphery of the first conductivity type base deep well region 6. A first conductivity type base implantation region 7 is disposed above the first conductivity type base well region 7. An ion implantation STI isolation structure 11 is provided above the first conductivity type base deep well region 6 in the entry region 8. An ion implantation STI isolation structure 11 is provided between the second conductivity type base implantation region 8 and the first conductivity type base implantation region 8 and above the first conductivity type base deep well region 6. An ion implantation STI isolation structure 11 is provided between the first conductivity type base implantation region 8 and the second conductivity type collector implantation region 5. An ion implantation STI isolation structure 11 is provided outside the second conductivity type collector implantation region 5 and above the four edges of the second conductivity type collector deep well region 3.

[0022] Furthermore, the second conductivity type collector injection region 5 is located inside the second conductivity type collector well region 4, with the former having a smaller area and a higher concentration than the latter.

[0023] The first conductivity type base injection region 8 is located inside the first conductivity type base well region 7, with a smaller area and higher concentration.

[0024] The second conductivity type emitter injection region 10 is located inside the second conductivity type emitter well region 9, with the former having a smaller area and a higher concentration than the latter.

[0025] Furthermore, the edge of the second conductivity type collector injection region 5 is tangent to the STI structure, the edge of the first conductivity type base injection region 8 is tangent to the STI structure, and the edge of the second conductivity type emitter injection region 10 is tangent to the STI structure.

[0026] Furthermore, the second conductivity type collector deep well region 3, the second conductivity type collector well region 4, and the second conductivity type collector injection region 5 together constitute the collector structure.

[0027] The first type of conductivity base deep well region 6, the first type of conductivity base well region 7, and the first type of conductivity base injection region 8 together constitute the base structure;

[0028] The second type of conductivity emitter well region 9 and the first type of conductivity emitter injection region 10 together constitute the emitter structure.

[0029] Furthermore, the second conductivity type collector well region 4 is not in direct contact with the first conductivity type base well region 7; the first conductivity type base well region 7 is not in direct contact with the second conductivity type emitter well region 9.

[0030] Furthermore, when the first conductivity type doped impurity is acceptor type, the second conductivity type doped impurity is donor type; when the first conductivity type doped impurity is donor type, the second conductivity type doped impurity is acceptor type.

[0031] Furthermore, the material filled inside the ion-implanted STI isolation structure 11 is SiO2 or a stacked structure, such as a SiO2 / SiN / SiO2 three-layer structure, a SiO2 / PSG two-layer structure, or a SiO2 / polysilicon two-layer structure, and is doped with ion implantation.

[0032] The ions implanted by STI doping are fluoride ions, chloride ions, bromide ions, iodide ions, or arsenic ions.

[0033] This invention also provides a method for fabricating a radiation-resistant bipolar device via STI ion implantation, the specific steps of which are as follows:

[0034] Step 1: Provide a silicon substrate 1 of the first conductivity type, perform photolithography and doping ion implantation, and anneal to form a buried layer 2 of the second conductivity type; perform photolithography and doping ion implantation on the upper surface of the buried layer 2 of the second conductivity type to form a collector deep well region 3 of the second conductivity type; perform photolithography and doping ion implantation on the upper surface of the collector deep well region 3 of the second conductivity type to form a base deep well region 6 of the first conductivity type, such as... Figure 1 As shown;

[0035] Step 2: An oxide layer and a SiN layer are grown on the upper surfaces of the second conductivity type collector deep well region 3 and the first conductivity type base deep well region 6. Active region photolithography and STI etching are then performed to form STI trenches, such as... Figure 2 As shown;

[0036] Step 3: Deposit SiO2 or various multilayer structures, such as a SiO2 / SiN / SiO2 three-layer structure, a SiO2 / PSG two-layer structure, or a SiO2 / polysilicon two-layer structure, within the STI trench to ensure electrode isolation. Then perform chemical mechanical polishing to form the STI shallow trench isolation region 11. Figure 3 As shown;

[0037] Step 4: Perform photolithography on the device surface, covering most of the surface with photoresist, exposing only the STI trench area, and then perform ion implantation on the STI trench filling material, such as... Figure 4 As shown;

[0038] Step 5: Photolithography and doped ion implantation are performed on the upper surfaces of the second conductivity type collector deep well region 3 and the first conductivity type base deep well region 6 to form the second conductivity type collector well region 4, the second conductivity type collector implantation region 5, the first conductivity type base well region 7, the first conductivity type base implantation region 8, the second conductivity type emitter well region 9, and the second conductivity type emitter implantation region 10, thus forming a complete radiation-hardened bipolar device structure, such as... Figure 5 As shown.

[0039] Furthermore, the second conductive type buried layer 2 can be omitted as needed.

[0040] When the second conductivity type buried layer 2 is present, the first conductivity type base deep well region 6 can be in direct contact with the second conductivity type buried layer 2. The second conductivity type collector deep well region 3 between the first conductivity type base deep well region 6 and the second conductivity type buried layer 2 can be squeezed to appear only below the edge 4, and the first conductivity type base deep well region 6 and the second conductivity type buried layer 2 can be in direct contact in the middle.

[0041] The total dose irradiation-hardened transistor prepared by the above method has an effective improvement in its total dose irradiation resistance, which can effectively solve the problem of current gain decrease after total dose irradiation.

[0042] The above description is merely a description of preferred embodiments of the present invention and is not intended to limit the scope of the present invention in any way. Any changes or modifications made by those skilled in the art based on the above disclosure shall fall within the protection scope of the claims.

Claims

1. A radiation-resistant bipolar device implanted by STI ion implantation, characterized in that, The structure includes, from bottom to top, a first conductivity type substrate (1), a second conductivity type buried layer (2), and a second conductivity type collector deep well region (3). A second conductivity type collector well region (4) is provided above the four edges of the second conductivity type collector deep well region (3). A second conductivity type collector injection region (5) is provided above the second conductivity type collector well region (4). A first conductivity type base deep well region (6) is provided above the interior of the second conductivity type collector deep well region (3). A first conductivity type base well region (7) is provided above the four edges of the first conductivity type base deep well region (6). A first conductivity type base injection region (8) is provided above the first conductivity type base well region (7). A second conductivity type emitter well is provided above the interior of the first conductivity type base deep well region (6). A second conductivity type emitter implantation region (10) is provided above the second conductivity type emitter well region (9). An ion implantation STI isolation structure (11) is provided between the second conductivity type emitter implantation region (10) and the first conductivity type base implantation region (8) and above the first conductivity type base deep well region (6). An ion implantation STI isolation structure (11) is provided between the first conductivity type base implantation region (8) and the second conductivity type collector implantation region (5). An ion implantation STI isolation structure (11) is provided outside the second conductivity type collector implantation region (5) and above the four edges of the second conductivity type collector deep well region (3). The material filled inside the ion implantation STI isolation structure (11) is SiO2 or a stacked structure, and it has been doped with ion implantation.

2. The STI-implanted radiation-resistant bipolar device according to claim 1, characterized in that: The second conductivity type collector injection region (5) is located inside the second conductivity type collector well region (4). The former has a smaller area and a higher concentration than the latter. The first conductivity type base injection region (8) is located inside the first conductivity type base well region (7), the former has a smaller area and a higher concentration than the latter; The second type of emitter injection region (10) is located inside the second type of emitter well region (9). The former has a smaller area and a higher concentration than the latter.

3. The STI-implanted radiation-resistant bipolar device according to claim 1, characterized in that: The edge of the second conductivity type collector implantation region (5) is tangent to the ion implantation STI isolation structure (11), the edge of the first conductivity type base implantation region (8) is tangent to the ion implantation STI isolation structure (11), and the edge of the second conductivity type emitter implantation region (10) is tangent to the ion implantation STI isolation structure (11).

4. The STI-implanted radiation-resistant bipolar device according to claim 1, characterized in that, The second conductivity type collector deep well region (3), the second conductivity type collector well region (4), and the second conductivity type collector injection region (5) together constitute the collector structure; The first conductivity type base deep well region (6), the first conductivity type base well region (7), and the first conductivity type base injection region (8) together constitute the base structure; The second type of conductive emitter well region (9) and the second type of conductive emitter injection region (10) together constitute the emitter structure.

5. The STI-implanted radiation-resistant bipolar device according to claim 1, characterized in that, The second type of collector well region (4) is not in direct contact with the first type of base well region (7); the first type of base well region (7) is not in direct contact with the second type of emitter well region (9).

6. The STI-implanted radiation-resistant bipolar device according to claim 1, characterized in that, When the first conductivity type doped impurity is acceptor type, the second conductivity type doped impurity is donor type; when the first conductivity type doped impurity is donor type, the second conductivity type doped impurity is acceptor type.

7. The STI-implanted radiation-resistant bipolar device according to claim 1, characterized in that, The ions implanted by STI doping are fluoride ions, chloride ions, bromide ions, iodide ions, or arsenic ions.

8. The method for fabricating a radiation-resistant bipolar device by STI ion implantation as described in any one of claims 1 to 7, characterized in that, Includes the following steps: (i) Provide a first conductivity type substrate (1), perform photolithography and doping ion implantation on its upper surface, and anneal to form a second conductivity type buried layer (2); perform photolithography and doping ion implantation on the upper surface of the second conductivity type buried layer (2), and anneal to form a second conductivity type collector deep well region (3); perform photolithography and doping ion implantation on the upper surface of the second conductivity type collector deep well region (3) to form a first conductivity type base deep well region (6). (ii) An oxide layer is grown and a SiN layer is deposited on the upper surface of the collector deep well region (3) of the second conductivity type and the base deep well region (6) of the first conductivity type. Active region photolithography and STI etching are performed to form STI trenches. (iii) Deposit SiO2 or a stacked structure in the STI trench to ensure electrode isolation, and then perform chemical mechanical polishing to form an ion-implanted STI isolation structure (11). (iv) Ion implantation is performed on the ion implantation STI isolation structure (11) with fluoride ions, chloride ions, bromide ions, iodide ions or arsenic ions, and then annealing is performed; (v) Photolithography and doped ion implantation are performed on the upper surfaces of the second conductivity type collector deep well region (3) and the first conductivity type base deep well region (6) to form the second conductivity type collector well region (4), the second conductivity type collector implantation region (5), the first conductivity type base well region (7), the first conductivity type base implantation region (8), the second conductivity type emitter well region (9), and the second conductivity type emitter implantation region (10), forming a complete radiation-hardened bipolar device structure.

9. The method according to claim 8, characterized in that, The first type of conductive base deep well region (6) and the second type of conductive buried layer (2) can be in direct contact.

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