Deep trench capacitor and method of manufacturing the same

Abstract

The present invention provides a deep trench capacitor and a manufacturing method thereof, wherein the deep trench capacitor comprises: a substrate having a first surface and a second surface opposite to each other, a deep trench formed from the first surface of the substrate toward the inside of the substrate, and the sidewalls of the deep trench on a cross section perpendicular to the first surface of the substrate comprising at least one first sidewall and at least one second sidewall connected alternately in sequence, the first sidewall being perpendicular to the first surface of the substrate, and the second sidewall having a protrusion, the protrusion protruding away from the normal direction perpendicular to the first surface of the substrate in the inside of the substrate away from the first sidewall; a dielectric material layer and a conductive material layer, alternately and conformally formed in the deep trench to form a deep trench capacitor, and the conductive material layer and the substrate and adjacent conductive material layers are electrically isolated by the dielectric material layer. The technical solution of the present invention increases the capacitance density, thereby reducing the power consumption of the circuit.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor integrated circuit manufacturing, and in particular to a deep trench capacitor and a manufacturing method thereof. Background Art

[0002] With the continuous improvement of chip integration, it has become a general trend to use deep trench capacitors (DTC) to replace traditional chip capacitors.

[0003] by Figure 1a and Figure 1b Taking the deep trench capacitor shown as an example, a plurality of deep trenches 12 are formed in the substrate 11, and the entire side wall of the deep trench 12 is perpendicular to the surface of the substrate 11. The deep trench capacitor is formed on the inner surface of the deep trench 12 and extends to the substrate 11 outside the deep trench 12. The deep trench capacitor includes a first electrode plate 131, an insulating layer 132 and a second electrode plate 133 stacked in sequence. The second electrode plate 133 fills the deep trench 12, and an isolation layer 111 is also formed between the first electrode plate 131 and the substrate 11.

[0004] The greater the capacitance density of the deep trench capacitor, the greater the benefit to the circuit power consumption. However, the existing method of increasing the material K value of the insulating layer 132 or reducing the thickness of the insulating layer 131 to increase the capacitance density of the deep trench capacitor is limited.

[0005] Therefore, a new method for increasing the capacitance density of deep trench capacitors is needed to further reduce circuit power consumption. Summary of the invention

[0006] The object of the present invention is to provide a deep trench capacitor and a manufacturing method thereof, so that the capacitance density is increased and the power consumption of the circuit is reduced.

[0007] To achieve the above object, the present invention provides a deep trench capacitor, comprising:

[0008] A substrate, the substrate having a first surface and a second surface opposite to each other, a deep trench being formed from the first surface of the substrate toward the inside of the substrate, the sidewalls of the deep trench comprising at least one first sidewall and at least one second sidewall connected alternately in sequence on a cross section perpendicular to the first surface of the substrate, wherein the first sidewall is perpendicular to the first surface of the substrate, the second sidewall has a protrusion, and the protrusion protrudes in the inside of the substrate away from the normal line perpendicular to the first surface of the substrate, opposite to the first sidewall;

[0009] Dielectric material layers and conductive material layers are alternately and conformally formed in the deep trench to form a deep trench capacitor. The conductive material layer and the substrate and adjacent conductive material layers are electrically isolated by the dielectric material layer.

[0010] Optionally, there are at least two deep trench capacitors, and protrusions of the adjacent deep trench capacitors on the same horizontal line are connected.

[0011] Optionally, in the protrusions in the adjacent deep trench capacitors on the same horizontal line, the dielectric material layers are connected to each other with the normal to the first surface of the substrate as the symmetry line, the conductive material layers are connected to each other, and the adjacent newly connected conductive material layers in the protrusions are electrically isolated by the newly connected dielectric material layers.

[0012] Optionally, the protrusion is in the shape of an arc or a polyhedron.

[0013] Optionally, the dielectric material layer and the conductive material layer further extend onto the substrate outside the deep trench.

[0014] The present invention also provides a method for manufacturing a deep trench capacitor, comprising:

[0015] Providing a substrate having a first surface and a second surface opposite to each other;

[0016] A deep trench is formed from the first surface of the substrate toward the inside of the substrate, wherein the sidewalls of the deep trench include at least one first sidewall and at least one second sidewall connected alternately in sequence on a cross section perpendicular to the first surface of the substrate, wherein the first sidewall is perpendicular to the first surface of the substrate, and the second sidewall has a protrusion, and the protrusion protrudes in the inside of the substrate away from the normal line perpendicular to the first surface of the substrate, away from the first sidewall;

[0017] Dielectric material layers and conductive material layers are conformally and alternately formed in the deep trench to form a deep trench capacitor. The conductive material layer and the substrate and adjacent conductive material layers are electrically isolated by the dielectric material layer.

[0018] Optionally, the step of forming a deep trench from the first surface of the substrate toward the interior of the substrate includes:

[0019] Step S21, covering the substrate with a patterned mask layer;

[0020] Step S22, using the patterned mask layer as a mask and adopting a dry etching process to etch the substrate to form a first opening, wherein the sidewall of the first opening is the first sidewall; conformally forming a first dielectric layer on the sidewall and bottom wall of the first opening, and etching the first dielectric layer on the bottom wall of the first opening to expose the substrate on the bottom wall of the first opening;

[0021] Step S23, etching the exposed substrate of the bottom wall of the first opening by a wet etching process to form a second opening having the protrusion below the bottom wall of the first opening, wherein the sidewall of the protrusion of the second opening is the second sidewall; conformally forming a second dielectric layer on the sidewall and bottom wall of the protrusion of the second opening, and etching the second dielectric layer of the bottom wall of the second opening to expose the substrate of the bottom wall of the second opening;

[0022] The steps S22 to S23 are executed in a loop in sequence.

[0023] Optionally, after the deep trench is formed from the first surface of the substrate toward the inside of the substrate, the first dielectric layer on all the first side walls and the second dielectric layer on all the second side walls in the deep trench are removed.

[0024] Optionally, there are at least two deep trench capacitors, and the at least two deep trench capacitors are formed simultaneously; when the substrate of the exposed bottom wall of the first opening is etched using a wet etching process in step S23 to form a protrusion of the second side wall, the protrusions of the adjacent deep trenches on the same horizontal line are connected.

[0025] Optionally, an etching selectivity ratio of the substrate to the first dielectric layer and the second dielectric layer is greater than 20.

[0026] Compared with the prior art, the technical solution of the present invention has the following beneficial effects:

[0027] 1. The deep trench capacitor of the present invention comprises: a substrate, the substrate having a first surface and a second surface opposite to each other, a deep trench formed from the first surface of the substrate toward the inside of the substrate, and the sidewalls of the deep trench on a cross section perpendicular to the first surface of the substrate comprising at least one first sidewall and at least one second sidewall connected alternately in sequence, wherein the first sidewall is perpendicular to the first surface of the substrate, and the second sidewall has a protrusion, and the protrusion protrudes in the direction of a normal line perpendicular to the first surface of the substrate away from the first sidewall inside the substrate; dielectric material layers and conductive material layers are alternately and conformally formed in the deep trench to form a deep trench capacitor, and the conductive material layers and the substrate and adjacent conductive material layers are electrically isolated by the dielectric material layers, so that the capacitance density is increased, thereby reducing the power consumption of the circuit.

[0028] 2. A method for manufacturing a deep trench capacitor of the present invention comprises forming a deep trench from the first surface of the substrate toward the interior of the substrate, wherein the sidewalls of the deep trench include at least one first sidewall and at least one second sidewall connected alternately in sequence on a cross section perpendicular to the first surface of the substrate, wherein the first sidewall is perpendicular to the first surface of the substrate, and the second sidewall has a protrusion, and the protrusion protrudes away from the first sidewall in the interior of the substrate in a normal direction perpendicular to the first surface of the substrate; dielectric material layers and conductive material layers are alternately and conformally formed in the deep trench to form a deep trench capacitor, and the conductive material layers are electrically isolated from the substrate and from adjacent conductive material layers by the dielectric material layers, so that the capacitance density is increased, thereby reducing the power consumption of the circuit. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1a is a schematic longitudinal cross-sectional view of a deep trench capacitor;

[0030] Figure 1b It is a top view schematic diagram of a deep trench;

[0031] Figure 2a is a schematic longitudinal cross-sectional view of a deep trench capacitor according to a first embodiment of the present invention;

[0032] Figure 2b yes Figure 2a A schematic top view of a deep trench in a deep trench capacitor shown;

[0033] Figure 3a is a schematic longitudinal cross-sectional view of a deep trench capacitor according to a second embodiment of the present invention;

[0034] Figure 3b yes Figure 3a A schematic top view of a deep trench in a deep trench capacitor shown;

[0035] Figure 4 is a schematic longitudinal cross-sectional view of a deep trench capacitor according to a third embodiment of the present invention;

[0036] Figure 5 is a flow chart of a method for manufacturing a deep trench capacitor according to an embodiment of the present invention;

[0037] Figure 6a to Figure 6l yes Figure 5 Schematic diagram of a device in a method for manufacturing a deep trench capacitor.

[0038] Among them, Figure 1a to Figure 6l The reference numerals are described as follows:

[0039] 11-substrate; 111-isolation layer; 12-deep trench; 131-first electrode plate; 132-insulating layer; 133-second electrode plate; 21-substrate; 210-patterned isolation layer; 211-patterned mask layer; 221-first opening; 222-second opening; 223-first side wall; 224-second side wall; 231-first dielectric layer; 232-second dielectric layer; 24-dielectric material layer; 25-conductive material layer; 26-insulating layer; 27-conductive plug. DETAILED DESCRIPTION

[0040] In order to make the purpose, advantages and features of the present invention more clear, the deep trench capacitor and the manufacturing method thereof proposed by the present invention are further described in detail below in conjunction with the accompanying drawings. It should be noted that the accompanying drawings are all in a very simplified form and are not in precise proportions, and are only used to conveniently and clearly assist in explaining the purpose of the embodiments of the present invention.

[0041] An embodiment of the present invention provides a deep trench capacitor, comprising: a substrate, the substrate having a first surface and a second surface opposite to each other, a deep trench formed from the first surface of the substrate toward the interior of the substrate, the deep trench sidewalls comprising at least one first sidewall and at least one second sidewall alternately connected in sequence on a cross section perpendicular to the first surface of the substrate, wherein the first sidewall is perpendicular to the first surface of the substrate, the second sidewall has a protrusion, the protrusion protrudes in the interior of the substrate away from the normal direction perpendicular to the first surface of the substrate opposite to the first sidewall; dielectric material layers and conductive material layers are alternately conformally formed in the deep trench to form a deep trench capacitor, the conductive material layers and the substrate, as well as adjacent conductive material layers, are electrically isolated by the dielectric material layers.

[0042] See below Figure 2a to Figure 4 The deep trench capacitor provided by this embodiment is described in detail, wherein: Figure 2a The deep grooves in the Figure 2b Schematic diagram of the longitudinal section of AA', Figure 3a The deep grooves in the Figure 3b Schematic diagram of the longitudinal section of BB'.

[0043] The substrate 21 has a first surface and a second surface opposite to each other, and a deep trench is formed from the first surface of the substrate 21 toward the inside of the substrate 21, and the sidewalls of the deep trench include at least one first sidewall 223 and at least one second sidewall 224 connected alternately in sequence on a cross section perpendicular to the first surface of the substrate 21, wherein the first sidewall 223 is perpendicular to the first surface of the substrate 21, and the second sidewall 224 has a protrusion, and the protrusion protrudes inside the substrate 21 away from the normal direction perpendicular to the first surface of the substrate 21, opposite to the first sidewall 223, so that the width of the deep trench having the first sidewall 223 is smaller than the width of the deep trench having the second sidewall 224.

[0044] Among them, Figure 2a and Figure 3a As shown in FIG. 1 , the sidewall of the deep trench away from the first surface is the second sidewall 224; or Figure 4 As shown, the sidewall of the deep trench at one end away from the first surface is the first sidewall 223 .

[0045] When the number of the deep trench capacitors is at least two, the protrusions of the adjacent deep trench capacitors on the same horizontal line are connected or disconnected. Figure 2a , Figure 2b and Figure 4 As shown, the protrusions of the adjacent deep trench capacitors on the same horizontal line are connected; Figure 3a and Figure 3b As shown, the protrusions of the adjacent deep trench capacitors on the same horizontal line are disconnected, that is, the substrate 21 is spaced between the protrusions of the adjacent deep trench capacitors on the same horizontal line.

[0046] The shape of the protrusion may be an arc (such as a sphere or an ellipsoid, etc.) or a polyhedron (such as a three-dimensional rhombus or a cuboid, etc.).

[0047] The dielectric material layers 24 and the conductive material layers 25 are conformally formed alternately in the deep trench to form a deep trench capacitor. The conductive material layers 25 and the substrate 21 as well as adjacent conductive material layers 25 are electrically isolated by the dielectric material layers 24 .

[0048] exist Figure 2a , Figure 3a and Figure 4 In the illustrated embodiment, three layers of the dielectric material layer 24 and two layers of the conductive material layer 25 are formed in the deep trench, and the deep trench is filled with the dielectric material layer 24. The number of layers of the dielectric material layer 24 and the conductive material layer 25 can be arbitrarily set as needed.

[0049] exist Figure 2a and Figure 4 In the illustrated embodiment, since the protrusions of the adjacent deep trench capacitors on the same horizontal line are connected, in the protrusions of the adjacent deep trench capacitors on the same horizontal line, the dielectric material layers 24 and the dielectric material layers 24 with a symmetry line perpendicular to the normal to the first surface of the substrate 21 are connected as a whole, the conductive material layers 25 and the conductive material layers 25 are connected as a whole, and the adjacent newly connected conductive material layers 25 in the protrusions are electrically isolated by the newly connected dielectric material layers 24.

[0050] The dielectric material layer 24 and the conductive material layer 25 also extend onto the substrate 21 outside the deep trench.

[0051] A patterned isolation layer 210 may also be formed on the substrate 21 outside the deep trench to isolate the substrate 21 from the dielectric material layer 24 and the portion of the conductive material layer 25 extending to the substrate 21 outside the deep trench. At this time, the dielectric material layer 24 and the conductive material layer 25 extend to the patterned isolation layer 210 outside the deep trench.

[0052] The dielectric material layer 24 is any insulating material known to those skilled in the art. Preferably, the dielectric material layer 24 is made of a material having a dielectric constant greater than 7.9 (7.9 is the dielectric constant of silicon nitride), such as a metal oxide material, so that the capacitance density of the deep trench capacitor is higher. It should be noted that the dielectric material layer 24 may also be made of other materials such as silicon oxide or silicon oxynitride.

[0053] The conductive material layer 25 is any conductive material known to those skilled in the art. Preferably, the conductive material layer 25 is at least one of metal, metal nitride and polysilicon.

[0054] In addition, the deep trench capacitor further includes a conductive plug 27 formed on each layer of the conductive material layer 25 extending to the periphery of the deep trench, so as to electrically lead out each layer of the conductive material layer 25 extending to the periphery of the deep trench.

[0055] From the above content, it can be seen that Figure 1a and Figure 1bIn the embodiment, the entire sidewall of the deep trench 12 is perpendicular to the surface of the substrate 11, so that the width of the deep trench 12 from top to bottom is the same. In the embodiment of the present invention, since the sidewall of the deep trench includes at least one first sidewall 223 and at least one second sidewall 224 connected alternately in sequence on the cross section perpendicular to the first surface of the substrate 21, and the first sidewall 223 is perpendicular to the first surface of the substrate 21, and the second sidewall 224 has a protrusion, and the protrusion protrudes away from the first sidewall 223 in the inner part of the substrate 21 away from the normal direction perpendicular to the first surface of the substrate 21, so that the width of the portion of the deep trench with the second sidewall 224 is greater than the width of the portion of the deep trench with the first sidewall 223, and further, when the depth range of the sidewall is the same, the surface area of ​​the second sidewall 224 with the protrusion is greater than the surface area of ​​the sidewall perpendicular to the first surface of the substrate 21. Then, Figure 1a and Figure 1b Compared with the structure in which the entire side wall of the deep groove 12 is perpendicular to the surface of the substrate 11, in the embodiment of the present invention, the second side wall 224 with a larger surface area is formed in the deep groove, so that the surface area of ​​the inner wall of the deep groove is increased, thereby increasing the area of ​​the conductive material layer 25 in the deep groove, thereby increasing the area of ​​the conductive material layer 25 per unit area of ​​the chip, increasing the capacitance density, and increasing the capacitance value that can be used per unit area of ​​the chip, thereby reducing circuit power consumption.

[0056] The deep trench capacitor provided by the present invention comprises: a substrate, the substrate having a first surface and a second surface opposite to each other, a deep trench formed from the first surface of the substrate toward the inside of the substrate, the sidewalls of the deep trench comprising at least one first sidewall and at least one second sidewall connected alternately in sequence on a cross section perpendicular to the first surface of the substrate, wherein the first sidewall is perpendicular to the first surface of the substrate, the second sidewall has a protrusion, the protrusion protrudes in the direction of the normal line perpendicular to the first surface of the substrate away from the first sidewall inside the substrate; a dielectric material layer and a conductive material layer are alternately and conformally formed in the deep trench to form a deep trench capacitor, the conductive material layer and the substrate and the adjacent conductive material layers are electrically isolated by the dielectric material layer. The deep trench capacitor of the present invention increases the capacitance density, thereby reducing the power consumption of the circuit.

[0057] An embodiment of the present invention provides a method for manufacturing a deep trench capacitor. Figure 5 , Figure 5 1 is a flow chart of a method for manufacturing a deep trench capacitor according to an embodiment of the present invention, wherein the method for manufacturing a deep trench capacitor comprises:

[0058] Step S1, providing a substrate, wherein the substrate has a first surface and a second surface opposite to each other;

[0059] Step S2, forming a deep trench from the first surface of the substrate toward the inside of the substrate, wherein the sidewalls of the deep trench include at least one first sidewall and at least one second sidewall connected alternately in sequence on a cross section perpendicular to the first surface of the substrate, wherein the first sidewall is perpendicular to the first surface of the substrate, and the second sidewall has a protrusion, and the protrusion protrudes in the inside of the substrate away from the normal line perpendicular to the first surface of the substrate, away from the first sidewall;

[0060] Step S3, alternately and conformally forming dielectric material layers and conductive material layers in the deep trench to form a deep trench capacitor, wherein the conductive material layer and the substrate and adjacent conductive material layers are electrically isolated by the dielectric material layer.

[0061] See 6a below. Figure 6l as well as Figure 2a to Figure 2b , Figure 3a to Figure 3b and Figure 4 The manufacturing method of the deep trench capacitor provided in this embodiment is introduced in detail.

[0062] According to step S1 , a substrate 21 is provided. The substrate 21 has a first surface and a second surface opposite to each other.

[0063] Step S2, forming a deep trench from the first surface of the substrate 21 toward the inside of the substrate 21, in a cross section perpendicular to the first surface of the substrate 21, the sidewall of the deep trench includes at least one first sidewall 223 and at least one second sidewall 224 which are alternately connected in sequence, wherein the first sidewall 223 is perpendicular to the first surface of the substrate 21, and the second sidewall 224 has a protrusion, and the protrusion protrudes inside the substrate 21 away from the normal direction perpendicular to the first surface of the substrate, opposite to the first sidewall 223, so that the width of the deep trench with the first sidewall 223 is smaller than the width of the deep trench with the second sidewall 224.

[0064] The step of forming a deep trench from the first surface of the substrate 21 toward the inside of the substrate 21 may include:

[0065] Step S21, as Figure 6a As shown, a patterned mask layer 211 is covered on the substrate 21;

[0066] Step S22, first, Figure 6aAs shown, the substrate 21 is etched by dry etching process with the patterned mask layer 211 as a mask to form a first opening 221, and the side wall of the first opening 221 is the first side wall 223, wherein, since the dry etching process has anisotropy, the first side wall 223 is perpendicular to the first surface of the substrate 21; then, as shown Figure 6b As shown, a first dielectric layer 231 is conformally formed on the sidewalls and bottom wall of the first opening 221, wherein the first dielectric layer 231 can be formed by a chemical vapor deposition process, a thermal oxidation process or an atomic layer deposition process; then, as shown Figure 6c As shown, the first dielectric layer 231 at the bottom wall of the first opening 221 is etched by a dry etching process to expose the substrate 21 at the bottom wall of the first opening 221, wherein, since the dry etching process has anisotropy, when the first dielectric layer 231 at the bottom wall of the first opening 221 is etched away, the first dielectric layer 231 at the side wall of the first opening 221 can be retained;

[0067] Step S23, first, Figure 6d As shown, the substrate 21 of the exposed bottom wall of the first opening 221 is etched by a wet etching process using the patterned mask layer 211 as a mask, so as to form a second opening 222 having the protrusion below the bottom wall of the first opening 221, and the sidewall of the protrusion of the second opening 222 is the second sidewall 224; wherein, since the wet etching process is isotropic, in the process of etching the substrate 21 of the exposed bottom wall of the first opening 221, both horizontal and vertical etching are performed simultaneously, so that the width of the formed second opening 222 is greater than the width of the first opening 221, that is, the width of the portion of the deep trench having the second sidewall 224 is greater than the width of the portion of the deep trench having the first sidewall 223; then, as Figure 6e As shown in FIG. 2 , a second dielectric layer 232 is conformally formed on the sidewalls and the bottom wall of the protruding portion of the second opening 222. In order to form the second dielectric layer 232 with a uniform thickness on the entire sidewalls and the bottom wall of the second opening 222, a thermal oxidation process or an atomic layer deposition process may be used to form the second dielectric layer 232. Then, as shown in FIG. Figure 6f As shown, the second dielectric layer 232 at the bottom wall of the second opening 222 is etched by a dry etching process to expose the substrate 21 at the bottom wall of the second opening 222, wherein, since the width of the first opening 221 is smaller than the width of the second opening 222, and an anisotropic dry etching process is used for etching, only the second dielectric layer 232 at a portion of the bottom wall of the second opening 222 is etched away, that is, the second dielectric layer 232 corresponding to the projection of the first opening 221 on the bottom wall of the second opening 222 is etched away to expose the substrate 21 at a portion of the bottom wall of the second opening 222.

[0068] Furthermore, it should be noted that, in the process of etching the second dielectric layer 232 on the bottom wall of the second opening 222, the first dielectric layer 231 on the side wall of the first opening 221 can also act as a mask, so that the width of the second dielectric layer 232 etched and removed on the bottom wall of the second opening 222 is slightly smaller than the width of the first opening 221.

[0069] Furthermore, through the above-mentioned steps S21 to S23, a first opening 221 and a second opening 222 are formed in the substrate 21; the steps S22 to S23 can be cyclically performed in sequence to form at least two first openings 221 and at least two second openings 222 in the substrate 21, so that the sidewall of the deep trench includes at least two first sidewalls 223 and at least two second sidewalls 224 that are alternately connected.

[0070] like Figure 6g to Figure 6i As shown, by cyclically executing step S22 to step S23, three first openings 221 and three second openings 222 are formed in the substrate 21, and the deep groove sidewalls include three groups of first side walls 223 and second side walls 224 that are alternately connected in sequence. It should be noted that the number of the first side walls 223 and the second side walls 224 can be set as needed. Preferably, the total number of the first side walls 223 and the second side walls 224 is 10.

[0071] Furthermore, in the step of forming a deep trench from the first surface of the substrate 21 toward the inside of the substrate 21, if the step S23 is the last step, then Figure 6i , Figure 2a and Figure 3a As shown, the end of the deep trench away from the first surface is the second opening 222, and the side wall of the deep trench away from the first surface is the second side wall 224; or, in the step of forming the deep trench from the first surface of the substrate 21 toward the inside of the substrate 21, if the step S22 is the last step, then Figure 4 As shown, one end of the deep trench away from the first surface is the first opening 221 , and the side wall of one end of the deep trench away from the first surface is the first side wall 223 .

[0072] The materials of the first dielectric layer 231 and the second dielectric layer 232 may be the same or different. Preferably, the first dielectric layer 231 and the second dielectric layer 232 may be at least one of insulating materials such as silicon oxide, silicon oxynitride or silicon nitride.

[0073] Preferably, the etching selectivity ratios of the substrate 21 to the first dielectric layer 231 and the second dielectric layer 232 are both greater than 20, so that each time the substrate 21 at the bottom wall of the exposed first opening 221 is etched using a wet etching process to form the second opening 222 and each time the substrate 21 is etched using a dry etching process to form the first opening 221, the first dielectric layer 231 on the side wall of the first opening 221 and the second dielectric layer 232 on the side wall of the second opening 222 are avoided from being etched or only a small amount of etching is performed.

[0074] Furthermore, after the end of the deep trench away from the first surface of the substrate 21 is formed, the patterned mask layer 211 may be removed or retained.

[0075] Furthermore, when the number of the deep trenches is at least two, the at least two deep trenches are formed simultaneously, and when the exposed substrate 21 at the bottom wall of the first opening 221 is etched by a wet etching process in the step S23 to form the protrusion of the second sidewall 224, the protrusions of the adjacent deep trenches on the same horizontal line are connected or disconnected. Figure 6i , Figure 2a , Figure 2b and Figure 4 As shown, the protrusions of the adjacent deep grooves on the same horizontal line are connected; Figure 3a and Figure 3b As shown, the protrusions of the adjacent deep trenches on the same horizontal line are disconnected, that is, the substrate 21 is spaced between the protrusions of the adjacent deep trenches on the same horizontal line.

[0076] The shape of the protrusion may be an arc (such as a sphere or an ellipsoid, etc.) or a polyhedron (such as a three-dimensional rhombus or a cuboid, etc.).

[0077] Step S3, see Figure 6k , dielectric material layers 24 and conductive material layers 25 are alternately and conformally formed in the deep trench to form a deep trench capacitor, and the conductive material layer 25 and the substrate 21 as well as adjacent conductive material layers 25 are electrically isolated by the dielectric material layer 24 .

[0078] Furthermore, after the deep trench is formed from the first surface of the substrate 21 toward the inside of the substrate 21 and before the dielectric material layer 24 and the conductive material layer 25 are sequentially and conformally formed alternately in the deep trench, as shown in FIG. Figure 6jAs shown, the first dielectric layer 231 of all the first sidewalls 223 in the deep trench and the second dielectric layer 232 of all the second sidewalls 224 can be removed. Alternatively, the first dielectric layer 231 of the first sidewalls 223 and the second dielectric layer 232 of the second sidewalls 224 in the deep trench can be retained, so that the first dielectric layer 231 and the second dielectric layer 232 together serve as the dielectric material layer 24 for electrically isolating the substrate 21 from the conductive material layer 25, or the first dielectric layer 231 and the second dielectric layer 232 together serve to isolate the dielectric material layer 24 from the substrate 21.

[0079] It should be noted that, in the step of forming the deep trench from the first surface of the substrate 21 toward the inside of the substrate 21, since the second dielectric layer 232 may be formed on the first side wall 223 and the first dielectric layer 231 may be formed on the second side wall 224, when removing the first dielectric layer 231 of all the first side walls 223 and the second dielectric layer 232 of all the second side walls 224 in the deep trench, the second dielectric layer 232 of all the first side walls 223 and the first dielectric layer 231 of all the second side walls 224 in the deep trench can also be removed.

[0080] The dielectric material layer 24 and the conductive material layer 25 may be formed by an atomic layer deposition process.

[0081] When the number of the deep trench capacitors is at least two, the at least two deep trench capacitors are formed simultaneously.

[0082] And, in Figure 6k , Figure 2a and Figure 4 In the illustrated embodiment, since the protrusions of the adjacent deep trench capacitors on the same horizontal line are connected, in the protrusions of the adjacent deep trench capacitors on the same horizontal line, the dielectric material layers 24 and the dielectric material layers 24 with a symmetry line perpendicular to the normal to the first surface of the substrate 21 are connected as a whole, the conductive material layers 25 and the conductive material layers 25 are connected as a whole, and the adjacent newly connected conductive material layers 25 in the protrusions are electrically isolated by the newly connected dielectric material layers 24.

[0083] exist Figure 6k , Figure 2a , Figure 3a and Figure 4In the embodiment shown, three layers of the dielectric material layer 24 and two layers of the conductive material layer 25 are formed in the deep trench, and the dielectric material layer 24 is used to fill the deep trench, the three layers of the dielectric material layer 24 include a first dielectric material layer, a second dielectric material layer, and a third dielectric material layer in sequence, and the two layers of the conductive material layer 25 include a first conductive material layer and a second conductive material layer in sequence, wherein the first dielectric material layer is used to electrically isolate the first conductive material layer from the substrate, and the second dielectric material layer is used to electrically isolate the second conductive material layer from the first conductive material layer. The material layer, the third dielectric material layer fills the deep trench, and the protrusions of the adjacent deep trench capacitors on the same horizontal line are connected, then the first dielectric material layer of the adjacent deep trench capacitors is connected to the first dielectric material layer to form a newly connected first dielectric material layer, and the first conductive material layer of the adjacent deep trench capacitors is connected to the first conductive material layer to form a newly connected first conductive material layer, and the newly connected first dielectric material layer is used to electrically isolate the newly connected first conductive material layer from the substrate, and the same can be applied to other dielectric material layers and conductive material layers.

[0084] Furthermore, the dielectric material layer 24 and the conductive material layer 25 extend onto the substrate 21 outside the deep trench. If the patterned mask layer 211 is not removed, the dielectric material layer 24 and the conductive material layer 25 extend onto the patterned mask layer 211 outside the deep trench.

[0085] The dielectric material layer 24 is any insulating material known to those skilled in the art. Preferably, the dielectric material layer 24 is made of a material having a dielectric constant greater than 7.9 (7.9 is the dielectric constant of silicon nitride), such as a metal oxide material, so that the capacitance density of the deep trench capacitor is higher. It should be noted that the dielectric material layer 24 may also be made of other materials such as silicon oxide or silicon oxynitride.

[0086] The conductive material layer 25 is any conductive material known to those skilled in the art. Preferably, the conductive material layer 25 is at least one of metal, metal nitride and polysilicon.

[0087] In addition, the manufacturing method of the deep trench capacitor further includes: forming a conductive plug on each layer of the conductive material layer 25 extending to the periphery of the deep trench, so as to electrically lead out each layer of the conductive material layer 25 extending to the periphery of the deep trench. Figure 6l , Figure 2a , Figure 3a and Figure 4For example, the steps of forming a conductive plug include: first, exposing each conductive material layer 25 extending to the periphery of the deep trench through an etching process, that is, sequentially etching the third dielectric material layer, the second conductive material layer, and the second dielectric material layer above the first conductive material layer extending to the periphery of the deep trench to expose the first conductive material layer, and sequentially etching the third dielectric material layer above the second conductive material layer extending to the periphery of the deep trench to expose the second conductive material layer; then, covering the dielectric material and the conductive material extending to the periphery of the deep trench with an insulating layer 26, that is, the insulating layer 26 covers the third dielectric material layer and each exposed conductive material layer; finally, etching the insulating layer 26 on the exposed first conductive material layer and the insulating layer 26 on the second conductive material layer to respectively form a first through hole (not shown) exposing the first conductive material layer and a second through hole (not shown) exposing the second conductive material layer; then, filling metal in the first through hole and the second through hole to form a plurality of conductive plugs 27.

[0088] From the above content, it can be seen that Figure 1a and Figure 1b In the embodiment of the present invention, the entire sidewall of the deep trench 12 is perpendicular to the surface of the substrate 11, so that the width of the deep trench 12 from top to bottom is the same. In the embodiment of the present invention, since the sidewall of the deep trench includes at least one first sidewall 223 and at least one second sidewall 224 connected alternately in sequence on the cross section perpendicular to the first surface of the substrate 21, and the first sidewall 223 is perpendicular to the first surface of the substrate 21, and the second sidewall 224 has a protrusion, and the protrusion protrudes away from the first sidewall 223 in the inner part of the substrate 21 in the normal direction perpendicular to the first surface of the substrate 21, so that the width of the portion of the deep trench with the second sidewall 224 is greater than the width of the portion of the deep trench with the first sidewall 223 (that is, the width of the second opening 222 is greater than the width of the first opening 221), and thus when the depth range of the sidewall is the same, the surface area of ​​the second sidewall 224 with the protrusion is greater than the surface area of ​​the sidewall perpendicular to the first surface of the substrate 21. Then, Figure 1a and Figure 1b Compared with the structure in which the entire side wall of the deep groove 12 is perpendicular to the surface of the substrate 11, in the embodiment of the present invention, the second side wall 224 with a larger surface area is formed in the deep groove, so that the surface area of ​​the inner wall of the deep groove is increased, thereby increasing the area of ​​the conductive material layer 25 in the deep groove, thereby increasing the area of ​​the conductive material layer 25 per unit area of ​​the chip, increasing the capacitance density, and increasing the capacitance value that can be used per unit area of ​​the chip, thereby reducing circuit power consumption.

[0089] The manufacturing method of the deep trench capacitor provided by the present invention comprises: providing a substrate, the substrate having a first surface and a second surface opposite to each other; forming a deep trench from the first surface of the substrate toward the inside of the substrate, wherein the sidewalls of the deep trench include at least one first sidewall and at least one second sidewall connected alternately in sequence on a cross section perpendicular to the first surface of the substrate, wherein the first sidewall is perpendicular to the first surface of the substrate, and the second sidewall has a protrusion, and the protrusion protrudes in the direction of a normal line perpendicular to the first surface of the substrate away from the first sidewall inside the substrate; and alternately conformally forming dielectric material layers and conductive material layers in the deep trench to form a deep trench capacitor, wherein the conductive material layer and the substrate and adjacent conductive material layers are electrically isolated by the dielectric material layer. The deep trench capacitor of the present invention increases the capacitance density, thereby reducing the power consumption of the circuit.

[0090] The above description is only a description of the preferred embodiments of the present invention, and is not intended to limit the scope of the present invention. Any changes or modifications made by a person skilled in the art in the field of the present invention based on the above disclosure shall fall within the scope of protection of the claims.

Claims

1. A deep trench capacitor, characterized in that: include: A substrate, the substrate having a first surface and a second surface opposite to each other, a deep trench being formed from the first surface of the substrate toward the inside of the substrate, the sidewalls of the deep trench comprising at least one first sidewall and at least one second sidewall connected alternately in sequence on a cross section perpendicular to the first surface of the substrate, wherein the first sidewall is perpendicular to the first surface of the substrate, the second sidewall has a protrusion, and the protrusion protrudes in the inside of the substrate away from the normal line perpendicular to the first surface of the substrate, opposite to the first sidewall; Dielectric material layers and conductive material layers are alternately and conformally formed in the deep trench to form a deep trench capacitor, and the conductive material layers and the substrate and adjacent conductive material layers are electrically isolated by the dielectric material layers; Among them, there are at least two deep trench capacitors, and the protrusions of the adjacent deep trench capacitors on the same horizontal line are connected, and the dielectric material layers in the connected protrusions with the normal line perpendicular to the first surface of the substrate as the symmetry line are connected to each other, and the conductive material layers are connected to each other, and the adjacent newly connected conductive material layers in the protrusions are electrically isolated by the newly connected dielectric material layer.

2. The deep trench capacitor according to claim 1, wherein: The protrusion is in the shape of an arc or a polyhedron.

3. The deep trench capacitor according to claim 1, wherein: The dielectric material layer and the conductive material layer also extend onto the substrate outside the deep trench.

4. A method for manufacturing a deep trench capacitor, characterized in that: include: Providing a substrate having a first surface and a second surface opposite to each other; A deep trench is formed from the first surface of the substrate toward the inside of the substrate, wherein the sidewalls of the deep trench include at least one first sidewall and at least one second sidewall connected alternately in sequence on a cross section perpendicular to the first surface of the substrate, wherein the first sidewall is perpendicular to the first surface of the substrate, and the second sidewall has a protrusion, and the protrusion protrudes in the inside of the substrate away from the normal line perpendicular to the first surface of the substrate, away from the first sidewall; Alternating and conformally forming dielectric material layers and conductive material layers in the deep trench to form a deep trench capacitor, wherein the conductive material layer and the substrate and adjacent conductive material layers are electrically isolated by the dielectric material layer; Among them, there are at least two deep trench capacitors, and the protrusions of the adjacent deep trench capacitors on the same horizontal line are connected, and the dielectric material layers in the connected protrusions with the normal line perpendicular to the first surface of the substrate as the symmetry line are connected to each other, and the conductive material layers are connected to each other, and the adjacent newly connected conductive material layers in the protrusions are electrically isolated by the newly connected dielectric material layer.

5. The method for manufacturing a deep trench capacitor according to claim 4, wherein: The step of forming a deep trench from the first surface of the substrate toward the inside of the substrate comprises: Step S21, covering the substrate with a patterned mask layer; Step S22, using the patterned mask layer as a mask and adopting a dry etching process to etch the substrate to form a first opening, wherein the sidewall of the first opening is the first sidewall; conformally forming a first dielectric layer on the sidewall and bottom wall of the first opening, and etching the first dielectric layer on the bottom wall of the first opening to expose the substrate on the bottom wall of the first opening; Step S23, etching the exposed substrate of the bottom wall of the first opening by a wet etching process to form a second opening having the protrusion below the bottom wall of the first opening, wherein the sidewall of the protrusion of the second opening is the second sidewall; conformally forming a second dielectric layer on the sidewall and bottom wall of the protrusion of the second opening, and etching the second dielectric layer of the bottom wall of the second opening to expose the substrate of the bottom wall of the second opening; The steps S22 to S23 are executed in a loop in sequence.

6. The method for manufacturing a deep trench capacitor according to claim 5, wherein: After the deep trench is formed from the first surface of the substrate toward the inside of the substrate, the first dielectric layer of all the first side walls and the second dielectric layer of all the second side walls in the deep trench are removed.

7. The method for manufacturing a deep trench capacitor according to claim 5, wherein: The at least two deep trench capacitors are formed simultaneously; when the substrate of the exposed bottom wall of the first opening is etched by a wet etching process in the step S23 to form the protrusion of the second side wall, the protrusions of the adjacent deep trenches on the same horizontal line are connected.

8. The method for manufacturing a deep trench capacitor according to claim 5, wherein: The etching selectivity ratios of the substrate to the first dielectric layer and the second dielectric layer are both greater than 20.

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