Deep trench isolation and manufacturing method thereof
By forming N-type and P-type doped layers in the deep trench isolation structure, the problem of insufficient breakdown voltage of deep trench isolation PN junction in the prior art is solved, and the device density and isolation effect are improved.
Patent Information
- Application Number
- CN202411098812.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-08-12
- Publication Date
- 2024-12-10
AI Technical Summary
In the prior art, the deep trench isolation PN junction breakdown voltage is limited, which cannot effectively prevent crosstalk and leakage between devices, resulting in insufficient device density.
An N-type buried layer and a P-type epitaxial layer are formed on the P-type substrate, and an N-type deep well is created thereon, followed by shallow trench isolation and deep trench on the deep well, with the surface and bottom of the deep trench uniform. Doping forms an N-type and P-type doped layer, filled with deep trench isolation, and an N-type heavily doped region is formed on the N-well.
The PN junction breakdown voltage is improved with deep trench isolation, enhances the isolation capability between devices, and achieves a higher density device layout.
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Figure CN119108412A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the field of semiconductor technology, and in particular to a deep trench isolation and a manufacturing method thereof. Background Art
[0002] Deep Trench Isolation (DTI) is an isolation technology used in integrated circuit manufacturing. It uses photolithography and etching techniques to form deep trenches, usually reaching the silicon substrate, effectively preventing crosstalk and leakage between devices and achieving higher density device layout.
[0003] See also Figure 1 , which shows a deep trench isolation in the prior art, wherein the respective figures are marked as:
[0004] 101—P-type substrate, 102—N-type buried layer, 103—N-type deep well on P-type epitaxy, 104—shallow trench isolation, 105—deep trench isolation, 106—P-type implantation, 107—N-well, 108—N-type heavily doped region.
[0005] The PN junction breakdown voltage of this structure is limited.
[0006] In order to solve the above problems, it is necessary to propose a new deep trench isolation and a manufacturing method thereof. Summary of the invention
[0007] In view of the above-mentioned shortcomings of the prior art, an object of the present invention is to provide a deep trench isolation and a manufacturing method thereof, so as to solve the problem of limited PN junction breakdown voltage of the deep trench isolation in the prior art.
[0008] To achieve the above objectives and other related objectives, the present invention provides a deep trench isolation, comprising:
[0009] A P-type substrate, an N-type buried layer is formed by implanting N-type impurities on the surface of the substrate, a P-type epitaxial layer is formed on the substrate, and an N-type deep well is formed on the epitaxial layer;
[0010] A shallow trench isolation is formed on the deep well to define an active area;
[0011] A deep trench is formed on the deep well, wherein the deep trench extends from the isolated upper surface of the shallow trench to the substrate;
[0012] A uniform N-type doping layer is formed on the surface of the deep trench;
[0013] A P-type doping layer is formed at the bottom of the deep trench, and the deep trench is filled with deep trench isolation;
[0014] An N-well is formed on the deep well, and an N-type heavily doped region is formed on the N-well.
[0015] Preferably, the doping concentration of the N-type doping layer is lower than the doping concentration of the P-type doping layer.
[0016] The present invention also provides a method for manufacturing the above-mentioned deep trench isolation, comprising:
[0017] Step 1: providing a P-type substrate, performing N-type impurity implantation on the surface of the substrate to form an N-type buried layer, forming a P-type epitaxial layer on the substrate, and forming an N-type deep well on the epitaxial layer by ion implantation;
[0018] Step 2: forming a shallow trench isolation on the deep well to define an active area, forming a deep trench, wherein the deep trench extends from the upper surface of the isolation of the shallow trench to the substrate;
[0019] Step 3: performing thermal diffusion in a phosphorus gas atmosphere to form a uniform N-type doping layer on the surface of the deep trench;
[0020] Step 4: forming a P-type doping layer at the bottom of the deep trench by ion implantation, and then forming a deep trench isolation filling the deep trench;
[0021] Step 5: define a well implantation region by photolithography, form an N-well by ion implantation, and then form an N-type heavily doped region on the N-well.
[0022] Preferably, the method for forming the shallow trench isolation in step 2 includes: forming a shallow trench on the deep well by photolithography and etching, and forming the shallow trench isolation by deposition and grinding.
[0023] Preferably, the method of etching the shallow trench in step 2 is dry etching.
[0024] Preferably, the grinding method in step 2 is chemical mechanical planarization grinding.
[0025] Preferably, in step 2, the deep trench is formed by photolithography and etching.
[0026] Preferably, the method of etching the deep trench in step 2 is dry etching.
[0027] Preferably, in step four, the deep trench isolation is formed by deposition and grinding methods.
[0028] Preferably, the grinding method in step 4 is chemical mechanical planarization.
[0029] Preferably, the doping concentration of the N-type doping layer in step 4 is lower than the doping concentration of the P-type doping layer.
[0030] As described above, the deep trench isolation and the manufacturing method thereof of the present invention have the following beneficial effects:
[0031] The invention improves the PN junction breakdown voltage of deep trench isolation. BRIEF DESCRIPTION OF THE DRAWINGS
[0032] Figure 1 Shown is a schematic diagram of deep trench isolation in the prior art;
[0033] Figure 2 Shown is a schematic diagram of the process flow of the present invention;
[0034] Figure 3 It is a schematic diagram showing the formation of an N-type buried layer according to the present invention;
[0035] Figure 4 It is a schematic diagram showing the formation of an N-type deep well according to the present invention;
[0036] Figure 5 It is a schematic diagram of forming shallow trench isolation according to the present invention;
[0037] Figure 6 It is a schematic diagram showing the formation of deep trenches and N-type doping layers according to the present invention;
[0038] Figure 7 It is a schematic diagram of forming shallow trench isolation according to the present invention;
[0039] Figure 8 It is a schematic diagram showing the formation of an N-well and an N-type heavily doped region according to the present invention;
[0040] Fig. 9 A schematic diagram showing a comparison of the PN junction and the depletion region boundary of the prior art structure and the structure of the present invention;
[0041] Fig.10 A schematic diagram showing the comparison of the longitudinal electric field distribution (at the tangent cuteline) of the deep trench isolation of the prior art structure and the structure of the present invention;
[0042] Fig.11 It is a schematic diagram showing a comparison of the breakdown voltage curves of the deep trench isolation PN junction of the prior art structure and the structure of the present invention. DETAILED DESCRIPTION
[0043] The following describes the embodiments of the present invention through specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention.
[0044] See also Figure 8 The present invention provides a deep trench isolation, comprising:
[0045] A P-type substrate 101, N-type impurities are implanted on the surface of the substrate 101 to form an N-type buried layer 102, a P-type epitaxial layer is formed on the substrate 101, and an N-type deep well 103 is formed on the epitaxial layer;
[0046] A shallow trench isolation 104 is formed on the deep well 103 to define an active region;
[0047] A deep trench is formed on the deep well 103, and the deep trench extends from the isolated upper surface of the shallow trench to the substrate 101;
[0048] A uniform N-type doping layer 106 - 2 is formed on the surface (sidewall and bottom) of the deep trench;
[0049] A P-type doping layer 106 is formed at the bottom of the deep trench, and the deep trench is filled with a deep trench isolation 105;
[0050] The materials of the shallow trench isolation 104 and the deep trench isolation 105 are spin-on-glass (SOG), dense oxide formed by high-density plasma chemical vapor deposition (HDP-CVDOX), silicon dioxide (SiO2), or double filling of silicon dioxide and silicon nitride (SIN).
[0051] An N-well 107 is formed on the deep well 103 , and an N-type heavily doped region 108 is formed on the N-well 107 .
[0052] In some embodiments, the doping concentration of the N-type doping layer 106 - 2 is lower than the doping concentration of the P-type doping layer 106 .
[0053] The isolation capability of the deep trench isolation 105 is strongly correlated with the PN junction breakdown voltage of the deep trench isolation 105 (PN junction breakdown voltage of the N-type buried layer 102 / P-type substrate 101). The lighter the concentration of the P-type substrate 101, the more depletion of the P-type substrate 101, and the higher the PN junction breakdown voltage of the deep trench isolation 105. Since the P-type substrate 101 cannot be easily changed, the present invention uses phosphorus atmosphere thermal diffusion to form a uniform N-type doping layer 106-2 on the surface of the deep trench sidewall, increases the depletion of the P-type substrate 101 on the sidewall of the deep trench isolation 105, pulls up a higher peak electric field at the bottom of the deep trench isolation 105, and improves the PN junction breakdown voltage of the deep trench isolation 105. Figures 9 to 11 The simulation data of Fig. 9 A schematic diagram showing a comparison of the PN junction and the depletion region boundary of the prior art structure and the structure of the present invention is shown. Fig.10 A schematic diagram showing the comparison of the longitudinal electric field distribution (cuteline) of the deep trench isolation 105 of the prior art structure and the structure of the present invention is shown. Fig.11 A schematic diagram showing a comparison of the breakdown voltage curves of the deep trench isolation 105PN junction of the prior art structure and the structure of the present invention is shown.
[0054] See also Figure 2 The present invention also provides a method for manufacturing the above-mentioned deep trench isolation, comprising:
[0055] Step 1: Provide a P-type substrate 101, and perform N-type impurity implantation on the surface of the substrate 101 to form an N-type buried layer 102, forming a Figure 3 The structure shown in FIG. 1 is a structure in which a P-type epitaxial layer is formed on a substrate 101, and an N-type deep well 103 is formed on the epitaxial layer by ion implantation, forming a structure as shown in FIG. Figure 4 The structure shown;
[0056] Step 2: forming a shallow trench isolation 104 on the deep well 103 to define an active area, forming a Figure 5 The structure shown forms a deep trench, which extends from the isolated upper surface of the shallow trench to the substrate 101;
[0057] In some embodiments, the method for forming the shallow trench isolation 104 in step 2 includes: forming a shallow trench on the deep well 103 by photolithography and etching, and forming the shallow trench isolation 104 by deposition and grinding. The material of the shallow trench isolation 104 is spin-on glass (SOG), dense oxide formed by high-density plasma chemical vapor deposition (HDP-CVDOX), silicon dioxide (SiO2), or double filling of silicon dioxide and silicon nitride (SIN) materials.
[0058] In some embodiments, the method of etching the shallow trench in step 2 is dry etching.
[0059] In some embodiments, the polishing method in step 2 is chemical mechanical planarization polishing.
[0060] In some embodiments, in step 2, the deep trench is formed by photolithography and etching.
[0061] In some embodiments, the method of etching the deep trench in step 2 is dry etching.
[0062] Step 3: Perform thermal diffusion in a phosphorus atmosphere to form a uniform N-type doping layer 106-2 on the surface (sidewall and bottom) of the deep trench. Figure 6 The structure shown;
[0063] Step 4: Form a P-type doping layer 106 at the bottom of the deep trench by ion implantation, and then form a deep trench isolation 105 filling the deep trench, so as to form Figure 7 The structure shown;
[0064] In some embodiments, in step 4, a deposition and grinding method is used to form a deep trench isolation 105. The material of the shallow trench isolation 104 is spin-on glass (SOG), dense oxide formed by high-density plasma chemical vapor deposition (HDP-CVDOX), silicon dioxide (SiO2), or double filling of silicon dioxide and silicon nitride (SIN).
[0065] In some embodiments, the polishing method in step 4 is chemical mechanical planarization.
[0066] In some embodiments, the doping concentration of the N-type doping layer 106 - 2 in step 4 is lower than the doping concentration of the P-type doping layer 106 , which can prevent the parasitic BJT (N-type buried layer 102 / P-type substrate 101 / N-type buried layer 102 ) from being turned on.
[0067] Step 5: Use photolithography to define the well injection area, use ion implantation to form an N well 107, and then form an N-type heavily doped region 108 on the N well 107 to form a Figure 8 The N-type regions on both sides of the deep trench isolation 105 are led out through the N-type heavily doped region 1081, with one end connected to a high potential and the other end connected to a low potential.
[0068] The isolation capability of the deep trench isolation 105 is strongly correlated with the PN junction breakdown voltage of the deep trench isolation 105 (PN junction breakdown voltage of the N-type buried layer 102 / P-type substrate 101). The lighter the concentration of the P-type substrate 101, the more depletion of the P-type substrate 101, and the higher the PN junction breakdown voltage of the deep trench isolation 105. Since the P-type substrate 101 cannot be easily changed, the present invention uses phosphorus atmosphere thermal diffusion to form a uniform N-type doping layer 106-2 on the surface of the deep trench sidewall, increases the depletion of the P-type substrate 101 on the sidewall of the deep trench isolation 105, pulls up a higher peak electric field at the bottom of the deep trench isolation 105, and improves the PN junction breakdown voltage of the deep trench isolation 105. Figures 9 to 11 The simulation data of Fig. 9 A schematic diagram showing a comparison of the PN junction and the depletion region boundary of the prior art structure and the structure of the present invention is shown. Fig.10 A schematic diagram showing the comparison of the longitudinal electric field distribution (cuteline) of the deep trench isolation 105 of the prior art structure and the structure of the present invention is shown. Fig.11 A schematic diagram showing a comparison of the breakdown voltage curves of the deep trench isolation 105PN junction of the prior art structure and the structure of the present invention is shown.
[0069] It should be noted that the illustrations provided in this embodiment are only used to illustrate the basic concept of the present invention in a schematic manner. Therefore, the drawings only show components related to the present invention rather than being 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 complicated.
[0070] In summary, the present invention improves the PN junction breakdown voltage of deep trench isolation. Therefore, the present invention effectively overcomes various shortcomings in the prior art and has high industrial utilization value.
[0071] 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 familiar with 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 a person of ordinary skill in the art without departing from the spirit and technical concept disclosed by the present invention shall still be covered by the claims of the present invention.
Claims
1. A deep trench isolation, characterized in that: include: A P-type substrate, an N-type buried layer is formed by implanting N-type impurities on the surface of the substrate, a P-type epitaxial layer is formed on the substrate, and an N-type deep well is formed on the epitaxial layer; A shallow trench isolation is formed on the deep well to define an active area; A deep trench is formed on the deep well, wherein the deep trench extends from the isolated upper surface of the shallow trench to the substrate; A uniform N-type doping layer is formed on the surface of the deep trench; A P-type doping layer is formed at the bottom of the deep trench, and the deep trench is filled with deep trench isolation; An N-well is formed on the deep well, and an N-type heavily doped region is formed on the N-well.
2. The method for manufacturing deep trench isolation according to claim 2, wherein: The doping concentration of the N-type doping layer is lower than the doping concentration of the P-type doping layer.
3. The method for manufacturing deep trench isolation according to claim 1, wherein: Step 1: providing a P-type substrate, performing N-type impurity implantation on the surface of the substrate to form an N-type buried layer, forming a P-type epitaxial layer on the substrate, and forming an N-type deep well on the epitaxial layer by ion implantation; Step 2: forming a shallow trench isolation on the deep well to define an active area, forming a deep trench, wherein the deep trench extends from the upper surface of the isolation of the shallow trench to the substrate; Step 3: performing thermal diffusion in a phosphorus gas atmosphere to form a uniform N-type doping layer on the surface of the deep trench; Step 4: forming a P-type doping layer at the bottom of the deep trench by ion implantation, and then forming a deep trench isolation filling the deep trench; Step 5: define a well implantation region by photolithography, form an N-well by ion implantation, and then form an N-type heavily doped region on the N-well.
4. The method for manufacturing deep trench isolation according to claim 2, wherein: The method for forming the shallow trench isolation in step 2 includes: forming a shallow trench on the deep well by photolithography and etching, and forming the shallow trench isolation by deposition and grinding.
5. The method for manufacturing deep trench isolation according to claim 2, wherein: In step 2, the deep trench is formed by photolithography and etching.
6. The method for manufacturing deep trench isolation according to claim 2, wherein: In step 4, the deep trench isolation is formed by deposition and grinding.
7. The method for manufacturing deep trench isolation according to claim 2, wherein: The doping concentration of the N-type doping layer in step 4 is lower than the doping concentration of the P-type doping layer.