A BJT device structure and manufacturing method thereof

Abstract

The present invention provides a BJT device structure and a method for fabricating the same, comprising a P-well; an N+ region located above the P-well; a barrier layer structure located above the N+ region, the barrier layer structure being a frame-shaped structure surrounding the periphery of the N+ region; the region within the barrier layer structure being the emitter region of the BJT device; a plurality of spaced-apart STI regions disposed above the N+ region of the emitter region, the upper surface of the P-well being higher than the bottom of the STI regions; a base region located outside the emitter region; and a collector region located outside the base region. The BJT device structure and method for fabricating the same have the following beneficial effects: Because the STI region of the emitter region is a discontinuous structure, the BJT device structure can significantly reduce the combined current between the emitter region and the base region, thereby effectively improving the amplification factor of the BJT device.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor manufacturing, and in particular to a BJT device structure and a manufacturing method thereof. Background Art

[0002] Bipolar junction transistors (BJTs) in general logic circuits are parasitic based on existing ion implantation conditions and cannot be adjusted independently, so they exhibit relatively small beta (amplification factor). For example, in BJT devices with an NPN structure, the current gain decreases significantly as the emitter area increases (other conditions remain unchanged). Taking the PNP structure as an example, its emitter is located in the middle of the entire transistor, and the edge is surrounded by a silicide block to reduce the recombination at the junction of the diffusion region and the STI region, thereby improving the performance of the BJT. The typical manufacturing process of CMOS in the current integration process is as follows: (1) Shallow trench isolation process to form the device active area; (2) Ion implantation to form P-type and N-type wells; (3) Gate oxide layer growth and gate formation; (4) Gate sidewall formation; (5) Ion implantation to form LDD region; (6) Gate main sidewall formation; (7) Ion implantation to form emitter, base and collector; (8) Deposition of SAB film; (9) Metal silicide-metal electrode formation; (10) Back-end metal layer interconnection and WAT testing. Among them, the production of BJT mainly involves processes such as (1), (2), (7) to (10).

[0003] However, the amplification factor of the BJT device structure in the prior art is generally low, so it is necessary to propose a new structure and method to effectively improve the amplification factor of the BJT device. Summary of the Invention

[0004] In view of the above-mentioned shortcomings of the prior art, an object of the present invention is to provide a BJT device structure and a manufacturing method thereof, so as to solve the problem of low amplification factor of BJT devices in the prior art.

[0005] To achieve the above and other related objectives, the present invention provides a BJT device structure, which at least includes:

[0006] A P-well; an N+ region located on the P-well; a barrier layer structure located on the N+ region, the barrier layer structure being a frame-shaped structure surrounding the periphery of the N+ region; the region within the barrier layer structure being the emitter region of the BJT device; a plurality of STI regions spaced apart from each other are provided on the N+ region of the emitter region, the upper surface of the P-well being higher than the bottom of the STI region;

[0007] A base region is located outside the emitter region; and a collector region is located outside the base region.

[0008] Preferably, the cross-sectional shape of the plurality of STI regions arranged at intervals from each other is a plurality of strip structures arranged at intervals from each other, and the plurality of strip structures are arranged at equal intervals within the barrier layer structure.

[0009] Preferably, the base region located outside the emitter region is isolated from the emitter region by an STI region and is led out from the P-well, and a P+ region is provided on the led-out P-well.

[0010] Preferably, a metal electrode constituting the base of the BJT device structure is provided on the P+ region.

[0011] Preferably, the collector region is composed of an N-well located outside the P-well and an N+ region on the N-well, and the collector region is isolated from the base region by an STI region.

[0012] Preferably, a metal electrode constituting a collector of the BJT device structure is provided on the N+ region constituting the collector region.

[0013] Preferably, the cross-sectional size of the emission region is 2 μm*2 μm.

[0014] The present invention also provides a method for manufacturing a BJT device structure, the method comprising at least the following steps:

[0015] Step 1: Simultaneously fabricating an STI region for isolating an emitter region, a base region, and a collector region, and a plurality of STI regions spaced apart from each other and located in a region where the emitter region is to be formed;

[0016] Step 2: performing ion implantation in the emitter region and the base region to be formed to form a P-well; performing ion implantation in the collector region to be formed to form an N-well; the upper surfaces of the P-well and the N-well are higher than the bottom of the STI region;

[0017] Step 3: Perform N-type ion heavy doping on the P-well to be formed as the emitter region and the N-well to be formed as the collector region to form an N+ region; perform P-type ion heavy doping on the P-well to be formed as the base region to form a P+ region;

[0018] Step 4: forming a barrier layer structure on the N+ region constituting the emitter region; the barrier layer structure is a frame-shaped structure surrounding the periphery of the N+ region of the emitter region;

[0019] Step 5: forming metal electrodes on the P+ region of the base region and on the N+ region of the collector region respectively.

[0020] Preferably, the method for forming a blocking layer structure on the N+ region constituting the emitter region in step 4 includes: (1) depositing a layer of metal silicide on the N+ region and the P+ region; and (2) forming the frame structure of the metal silicide surrounding the periphery of the N+ region on the N+ region constituting the emitter region using a photolithography and etching process.

[0021] Preferably, the method further comprises step six, performing a WAT ​​test on the BJT device structure to extract its current gain.

[0022] As described above, the BJT device structure and its fabrication method of the present invention have the following beneficial effects: Since the STI region of the emitter region of the BJT device structure of the present invention is a discontinuous structure, the recombination current between the emitter region and the base region can be significantly reduced, thereby effectively improving the amplification factor of the BJT device. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 Shown is a schematic diagram of the cross-sectional structure of a BJT device of the present invention;

[0024] Figure 2 Shown is a schematic diagram of the cross-sectional structure of a BJT device of the present invention;

[0025] Figure 3 Shown is a graph showing the relationship between the amplification factor and the electrical parameter Vbe of the BJT device of the present invention;

[0026] Figure 4 Shown is a graph showing the relationship between the base current and the electrical parameter Vbe of the BJT device of the present invention;

[0027] Figure 5a A TCAD simulation diagram showing the electron current density of a BJT device in the prior art;

[0028] Figure 5b The figure shows the TCAD simulation of the electron current density of the BJT device of the present invention. DETAILED DESCRIPTION

[0029] The following describes the embodiments of the present invention through specific examples. Those skilled in the art will readily understand the other advantages and benefits of the present invention from the disclosure herein. The present invention may also be implemented or applied through various other specific embodiments, and the details in this specification may be modified or altered based on different viewpoints and applications without departing from the spirit of the present invention.

[0030] See also Figures 1 to 5bIt should be noted that the diagrams provided in this embodiment are merely schematic illustrations of the basic concept of the present invention. Therefore, the diagrams only show components related to the present invention and are not drawn according to the number, shape, and size of components in actual implementation. In actual implementation, the type, quantity, and proportion of each component may be changed arbitrarily, and the component layout may also be more complex.

[0031] The present invention provides a BJT device structure, such as Figure 1 As shown, Figure 1 The schematic diagram of the cross-sectional structure of the BJT device of the present invention is shown, which comprises at least: a P-well (P-Well); an N+ region 01 located on the P-well (P-Well); a barrier layer structure 02 located on the N+ region 01, the barrier layer structure 02 being a frame structure surrounding the periphery of the N+ region; the barrier layer structure as shown in FIG. Figure 2 As shown, Figure 2 The schematic diagram of the cross-sectional structure of the BJT device of the present invention is shown. The area within the barrier layer structure 02 is the emitter region of the BJT device; the emitter region is composed of the P well and the N+ region located on the P well. A plurality of STI regions 03 arranged at intervals are provided on the N+ region 01 of the emitter region, and the upper surface of the P well is higher than the bottom of the STI region; Figure 2 As shown, the STI region in the emitter region is located inside the barrier layer structure, and the multiple STI regions 03 are discontinuous structures located in the emitter region. In this embodiment, the discontinuous structures are arranged in intervals within the frame structure. The frame structure of the barrier layer structure surrounds the periphery of the N+ region in the emitter region.

[0032] like Figure 2 As shown, in the present invention, the cross-sectional shape of the multiple mutually spaced STI regions 03 is a plurality of mutually spaced strip structures, and the multiple strip structures are evenly spaced within the barrier layer structure.

[0033] The BJT device structure of the present invention further includes a base region located outside the emitter region; and a collector region located outside the base region. Figure 1 As shown, the base region located outside the emitter region is isolated from the emitter region by the STI region and is led out from the P well, and a P+ region is provided on the led out P well. Figure 2 It can be seen that the base region located outside the emitter region is composed of the P well and the P+ region 04 located on the P well, as shown in FIG. Figure 1 As shown, the P-well constituting the base region is led out from the P-well constituting the emitter region. The N+ region 01 of the emitter region and the P+ region 04 of the base region are isolated by the STI region.

[0034] The present invention further provides a metal electrode on the P+ region that forms the base of the BJT device structure. Figure 1 and Figure 2 The metal electrode on the P+ region 04 is not shown.

[0035] The present invention further, as Figure 2 As shown, the collector region is composed of an N-well located outside the P-well and an N+ region 05 on the N-well. The collector region and the base region are isolated by an STI region. Figure 1 The collector region is located at the periphery of the base region, the N well is provided at the periphery of the P well, the N+ region 05 is provided on the N well, the N well and the N+ region located thereon constitute the collector region of the BJT device structure, and the collector region and the base region are isolated by the STI region.

[0036] The present invention further provides that the N+ region 05 located on the N well is provided with a metal electrode constituting the collector of the BJT device structure. Figure 1 and Figure 2 The metal electrode located on the N+ region 05 is not shown.

[0037] Furthermore, the cross-sectional dimension of the emitter region is 2 μm*2 μm. The BJT device of the present invention is an NPN type.

[0038] The present invention also provides a method for manufacturing the BJT device structure, which method comprises at least the following steps:

[0039] Step 1: Simultaneously fabricate an STI region for isolating the emitter region, the base region, and the collector region, and a plurality of STI regions spaced apart from each other in the region where the emitter region is to be formed; Figure 1 As shown, in step 1, after etching a shallow trench isolation region on the substrate, silicon oxide is filled to form an STI region to form an active region. The emitter region, base region and collector region of the BJT device are made in the active region, and the emitter region and the base region are isolated by the STI region, and the base region and the collector region are isolated by the STI region. In this step, a plurality of mutually spaced STI regions 03 are first made in the region where the emitter region is to be formed, and the plurality of mutually spaced STI regions 03 in the emitter region are formed simultaneously with the STI region for isolating the emitter region from the base region and the STI region for isolating the base region from the collector region. By Figure 2 It can be seen that the cross section of the multiple STI regions spaced apart from each other in the emitter region ( Figure 1 The top view is Figure 2 ) is in the shape of a strip structure arranged at equal intervals.

[0040] Step 2: Ion implantation is performed in the emitter region and base region to be formed to form a P well ( Figure 1 P-Well in the collector region to be formed by ion implantation to form an N well ( Figure 1 The upper surfaces of the P-well and the N-well are higher than the bottom of the STI region;

[0041] Step three, perform N-type ion heavy doping on the P-well to form the emitter region and the N-well to form the collector region to form, respectively, to form an N+ region; perform P-type ion heavy doping on the P-well to form the base region to form a P+ region; In this step three, perform N-type heavy doping ion injection on the P-well of the emitter region to be formed to form an N+ region 01 constituting the emitter region, and perform N-type heavy doping ion injection on the N-well (N-Well) to form the collector region to form an N+ region 05 constituting the collector region; and perform P-type heavy doping ion injection on the P-well to form the base region to form a P+ region 04 constituting the base region.

[0042] Step 4: forming a blocking layer structure on the N+ region constituting the emitter region; Figure 2 As shown, the blocking layer structure 02 is a frame-shaped structure surrounding the periphery of the N+ region of the emitter region; further, the method of forming the blocking layer structure on the N+ region constituting the emitter region in step 4 includes: (1) depositing a layer of metal silicide on the N+ region and the P+ region; (2) forming the frame-shaped structure of the metal silicide surrounding the periphery of the N+ region on the N+ region constituting the emitter region using a photolithography and etching process. The formation of the blocking layer structure includes transferring the pattern of the blocking layer structure to the photoresist on the N+ region on the P-well after a one-time exposure using a mask corresponding to the blocking layer structure. Thereafter, the remaining metal silicide is removed by development and etching, leaving the frame-shaped structure.

[0043] Step 5: Form metal electrodes on the P+ region of the base and on the N+ region of the collector, respectively.

[0044] The method further includes step 6, performing a WAT ​​test on the BJT device structure to extract its current gain. Figure 3 and Figure 4 As shown, Figure 3 The figure shows the relationship between the gain factor and the electrical parameter Vbe for BJT devices in the prior art and the present invention. Curve A shows the relationship between the gain factor and the electrical parameter Vbe for the BJT device in the prior art; Curve B shows the relationship between the gain factor and the electrical parameter Vbe for the BJT device in the present invention. It can be seen that the BJT device structure of the present invention improves the gain factor by 54%.

[0045] Figure 4It shows the relationship curve between the current and the electrical parameter Vbe of the BJT device in the prior art and the present invention. Among them, ib (Case 1) and ic (Case 1) are the relationship curves between the current and the electrical parameter Vbe of the BJT device in the prior art, while ib (Case 2) and ic (Case 2) are the relationship curves between the current and the electrical parameter Vbe of the BJT device of the present invention. It can be seen that based on the curve relationship diagram, it can be seen that the main reduction is the Ib current. For the NPN type, Ib is the electron current injected from the base region (base) to the emitter region (emitter), and the structure of the present invention can significantly reduce this current. The TCAD simulation results show that the BJT structure proposed in this patent, such as Figure 5b As shown, Figure 5a The TCAD simulation diagram of the electron current density of the BJT device of the prior art is shown. Figure 5b The TCAD simulation diagram of the electron current density of the BJT device of the present invention shows that the BJT device of the present invention significantly reduces the electron current flowing into the base region, thereby effectively improving Beta. In the BJT device of the present invention, a discontinuous STI region is provided on the N+ region of the emitter region, which significantly reduces the recombination current Ib between the base and emitter. The hole current density of the new structure proposed by the present invention is significantly smaller than that of the existing structure. Figure 5b As shown, the amplification factor is increased.

[0046] In summary, the BJT device structure and its fabrication method of the present invention have the following beneficial effects: Because the STI region in the emitter region of the present invention is discontinuous, the combined current between the emitter and base regions can be significantly reduced. This effectively increases the amplification factor of the BJT device. Therefore, the present invention effectively overcomes the various shortcomings of the prior art and has high industrial applicability.

[0047] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the present invention. Anyone skilled in the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by one of ordinary skill in the art without departing from the spirit and technical principles disclosed herein are intended to be covered by the claims of the present invention.

Claims

1. A BJT device structure, characterized in that: The structure includes at least: A P-well; an N+ region located on the P-well; a barrier layer structure located on the N+ region, the barrier layer structure being a frame-shaped structure surrounding the periphery of the N+ region; the region within the barrier layer structure being the emitter region of the BJT device; a plurality of STI regions spaced apart from each other are provided on the N+ region of the emitter region, the upper surface of the P-well being higher than the bottom of the STI regions; the cross-section of the plurality of spaced apart STI regions being a plurality of spaced apart strip structures, the plurality of strip structures being equally spaced apart from each other within the barrier layer structure; a base region located outside the emitter region; A collector region is located outside the base region.

2. A BJT device structure according to claim 1, characterized in that: The base region located outside the emitter region is isolated from the emitter region by the STI region and is led out from the P well, and a P+ region is provided on the led-out P well.

3. A BJT device structure according to claim 2, characterized in that: A metal electrode constituting the base of the BJT device structure is provided on the P+ region.

4. A BJT device structure according to claim 3, characterized in that: The collector region is composed of an N well located outside the P well and an N+ region on the N well. The collector region and the base region are isolated by an STI region.

5. A BJT device structure according to claim 4, characterized in that: A metal electrode constituting the collector of the BJT device structure is provided on the N+ region constituting the collector region.

6. The BJT device structure according to claim 1, wherein: The cross-sectional size of the emission region is 2 μm*2 μm.

7. The method for manufacturing a BJT device structure according to any one of claims 1 to 6, characterized in that: The method comprises at least the following steps: Step 1: Simultaneously fabricating an STI region for isolating an emitter region, a base region, and a collector region, and a plurality of STI regions spaced apart from each other and located in a region where the emitter region is to be formed; Step 2: performing ion implantation in the emitter region and the base region to be formed to form a P-well; performing ion implantation in the collector region to be formed to form an N-well; the upper surfaces of the P-well and the N-well are higher than the bottom of the STI region; Step 3: Perform N-type ion heavy doping on the P-well where the emitter region is to be formed and on the N-well where the collector region is to be formed to form an N+ region; Performing heavy P-type ion doping on the P-well where the base region is to be formed to form a P+ region; Step 4: forming a barrier layer structure on the N+ region constituting the emitter region; the barrier layer structure is a frame-shaped structure surrounding the periphery of the N+ region of the emitter region; Step 5: forming metal electrodes on the P+ region of the base region and on the N+ region of the collector region respectively.

8. The method for manufacturing a BJT device structure according to claim 7, wherein: The method for forming a blocking layer structure on the N+ region constituting the emitter region in step 4 includes: (1) depositing a layer of metal silicide on the N+ region and the P+ region; and (2) forming the frame structure of the metal silicide surrounding the periphery of the N+ region on the N+ region constituting the emitter region using photolithography and etching processes.

9. The method for manufacturing a BJT device structure according to claim 7, wherein: The method also includes step six, performing a WAT ​​test on the BJT device structure to extract its current gain.

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