Method of making a trench

Abstract

The application provides a trench manufacturing method, comprising the following steps: providing a substrate, sequentially forming an oxidation layer and a titanium nitride layer on the substrate; oxidizing the titanium nitride layer in different regions in different degrees, so that the titanium nitride layer with different thicknesses is oxidized to form a titanium oxide layer, and the thickness of the oxidized titanium nitride layer is greater than or equal to zero and less than or equal to the thickness of the titanium nitride layer; sequentially etching the titanium oxide layer, or / and the titanium nitride layer and the oxidation layer and the substrate below the titanium nitride layer in each region to form trenches with different depths. The application oxidizes the titanium nitride layer in different regions in different degrees, so that the titanium nitride layer with different thicknesses is oxidized to form a titanium oxide layer, that is, the thickness of the titanium oxide layer formed in each region is different, the etching rate of the titanium nitride layer and the titanium oxide layer is different, the thicker the titanium oxide layer is, the slower the etching is, and the shallower the formed trench is, so that trenches with different depths can be formed in the same etching step.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of semiconductor integrated circuit, in particular to a trench manufacturing method. BACKGROUND

[0002] In the manufacturing of advanced semiconductor devices, the accurate control of multi-level trench structure is the key to achieve high performance. In the traditional process, trenches of different depths need to be completed through multiple mask deposition, lithography and etching steps, resulting in complex process flow, long cycle, high cost, and cumulative overlay error. For example: double-trench structure requires two independent masks and etching, and the cumulative overlay error leads to the decrease of control accuracy of trench depth and width.

[0003] In addition, the prior art usually uses a single material mask or a fixed double-layer structure mask, and the etching selectivity is fixed, which cannot dynamically adjust the etching rate of different regions, limiting the dynamic adjustment of trench depth and width.

[0004] Therefore, there is an urgent need for a manufacturing method that can simultaneously realize the differentiation of multi-level trench depth. SUMMARY

[0005] The purpose of the present application is to provide a trench manufacturing method that can form trenches of different depths in one etching process.

[0006] To solve the above technical problems, the present application provides a trench manufacturing method, comprising the following steps:

[0007] A substrate is provided, and an oxide layer and a titanium nitride layer are formed on the substrate in sequence;

[0008] The titanium nitride layer in different regions is oxidized to different degrees, so that the titanium nitride layer of different thicknesses is oxidized to form a titanium oxide layer, and the thickness of the oxidized titanium nitride layer is greater than or equal to zero and less than or equal to the thickness of the titanium nitride layer; and

[0009] The oxide layer, the titanium nitride layer and the substrate below each region are etched in sequence to form trenches of different depths.

[0010] Optionally, the method for oxidizing the titanium nitride layer in different regions to different degrees and etching to form trenches of different depths comprises:

[0011] A first mask layer is formed on the titanium nitride layer, and a first oxidation window exposing the titanium nitride layer is formed in the first mask layer;

[0012] The titanium nitride layer is oxidized through the first oxidation window, so that the titanium nitride layer below the first oxidation window is completely oxidized to form a titanium oxide layer;

[0013] removing the first mask layer, and forming a second mask layer on the titanium nitride layer and the titanium oxide layer;

[0014] forming a first etching window exposing the titanium oxide layer and a second etching window exposing the titanium nitride layer in the second mask layer;

[0015] performing etching process with the second mask layer as a mask, forming a first trench penetrating the titanium oxide layer and the oxide layer and extending into the substrate under the first etching window, and forming a second trench penetrating the titanium nitride layer and the oxide layer and extending into the substrate under the second etching window, the depth of the second trench being greater than the depth of the first trench; and

[0016] removing the second mask layer.

[0017] Optionally, the first mask layer and the second mask layer are photoresist layers.

[0018] Optionally, while forming the first etching window exposing the titanium nitride layer in the first mask layer, a second oxidation window is also formed in the first mask layer, the depth of the second oxidation window being less than the depth of the first oxidation window.

[0019] Optionally, while oxidizing the titanium nitride layer through the first oxidation window, the titanium nitride layer is also oxidized through the second oxidation window, so that the titanium oxide layer is formed under the second oxidation window by oxidizing part of the thickness of the titanium nitride layer;

[0020] while forming the first etching window and the second etching window in the second mask layer, a third etching window exposing the titanium oxide layer is also formed in the second mask layer, the third etching window corresponding to the second oxidation window;

[0021] during the etching process with the second mask layer as a mask, a third trench penetrating the titanium oxide layer, the titanium nitride layer and the oxide layer and extending into the substrate is formed under the third etching window, the depth of the third trench being less than the depth of the second trench and greater than the depth of the first trench.

[0022] Optionally, the method for forming trenches with different depths by oxidizing and etching the titanium nitride layer in different regions comprises:

[0023] forming a first mask layer on the titanium nitride layer, and forming a first oxidation window exposing the titanium nitride layer and a second oxidation window not exposing the titanium nitride layer in the first mask layer;

[0024] oxidizing the titanium nitride layer through the first oxidation window and the second oxidation window, so that the titanium nitride layer under the first oxidation window is entirely oxidized to form a titanium oxide layer, and a partial thickness of the titanium nitride layer under the second oxidation window is oxidized to form a titanium nitride layer;

[0025] forming a first trench through the titanium oxide layer and the oxide layer and extending into the substrate under the first oxidation window, and forming a third trench through the titanium oxide layer, the titanium nitride layer and the oxide layer and extending into the substrate under the second oxidation window, the third trench having a depth greater than that of the first trench, by performing an etching process with the first mask layer as a mask; and

[0026] removing the first mask layer.

[0027] Optionally, a method for forming trenches with different depths by oxidizing different regions of the titanium nitride layer to different degrees comprises:

[0028] forming a first mask layer on the titanium nitride layer, and forming a first oxidation window exposing the titanium nitride layer and a second oxidation window not exposing the titanium nitride layer in the first mask layer;

[0029] oxidizing the titanium nitride layer through the first oxidation window and the second oxidation window, so that the titanium nitride layer under the first oxidation window is entirely oxidized to form a titanium oxide layer, and a partial thickness of the titanium nitride layer under the second oxidation window is oxidized to form a titanium nitride layer;

[0030] forming a second mask layer on the first mask layer, the second mask layer covering the first mask layer and filling the first oxidation window and the second oxidation window;

[0031] forming a first etching window exposing the titanium oxide layer and corresponding to the first oxidation window, and a third etching window exposing the titanium oxide layer and corresponding to the second oxidation window, and a second etching window exposing the titanium nitride layer, in the second mask layer and the first mask layer;

[0032] forming a first trench through the titanium oxide layer and the oxide layer and extending into the substrate under the first etching window, forming a second trench through the titanium nitride layer and the oxide layer and extending into the substrate under the second etching window, and forming a third trench through the titanium oxide layer, the titanium nitride layer and the oxide layer and extending into the substrate under the third etching window; the depth of the second trench is greater than the depth of the first trench, the depth of the third trench is greater than the depth of the first trench and less than the depth of the second trench; and

[0033] removing the second mask layer and the first mask layer.

[0034] Optionally, the material of the first mask layer and the second mask layer comprises silicon oxide.

[0035] The method for forming the first oxidation window and the second oxidation window in the first mask layer comprises:

[0036] forming a photoresist layer on the first mask layer;

[0037] exposing and developing the photoresist layer to form a patterned photoresist layer by using a half-tone mask or a step mask;

[0038] etching the first mask layer by using the patterned photoresist layer as a mask to form the first oxidation window and the second oxidation window with different depths in the first mask layer; and

[0039] removing the patterned photoresist layer.

[0040] Optionally, the cross-sectional size of the first oxidation window is different from that of the second oxidation window; and / or the cross-sectional size of the first etching window, the second etching window and the third etching window is different.

[0041] Optionally, after forming the trench, the method further comprises: removing the titanium nitride layer and the oxide layer.

[0042] In summary, in the trench manufacturing method provided by the present application, a substrate is provided, and an oxidation layer and a titanium nitride layer are sequentially formed on the substrate. Then, the titanium nitride layer in different regions is oxidized to different degrees, so that the titanium nitride layer with different thicknesses is oxidized to form titanium oxide layers, and the thickness of the oxidized titanium nitride layer is greater than or equal to zero and less than or equal to the thickness of the titanium nitride layer. Then, the oxidation layer, the titanium nitride layer, and the substrate under the oxidation layer are etched to form trenches with different depths. In the present application, the titanium nitride layer in different regions is oxidized to different degrees, so that the titanium nitride layer with different thicknesses is oxidized to form titanium oxide layers, that is, the thickness of the titanium oxide layer formed in each region is different, the etching rate of the titanium nitride layer and the titanium oxide layer is different, the thicker the titanium oxide layer, the slower the etching, and the shallower the trench formed, so that trenches with different depths can be formed in the same etching step.

[0043] Further, the cross-sectional sizes of the first oxidation window and the second oxidation window are different, and / or the cross-sectional sizes of the first etching window, the second etching window, and the third etching window are different, so that trenches with different widths and different depths can be formed.

[0044] Further, the first oxidation window and the second oxidation window are formed in the first mask layer, and the titanium nitride layer is oxidized, and then etching process is directly performed on the first mask layer as a mask. Since the etching selectivity ratio of titanium nitride and titanium oxide is large, the first mask layer reserved at the bottom of the second oxidation window compensates the thickness of the titanium oxide layer at the bottom, so as to lower the etching selectivity ratio, thereby accurately controlling the etching depth. BRIEF DESCRIPTION OF DRAWINGS

[0045] Figure 1 It is a flowchart of the trench manufacturing method provided by an embodiment of the present application.

[0046] Figure 2 It is a structural schematic diagram after the titanium nitride layer is formed according to the first embodiment of the present application.

[0047] Figure 3 It is a structural schematic diagram after the titanium oxide layer is formed according to the first embodiment of the present application.

[0048] Figure 4 It is a structural schematic diagram after the second mask layer is formed according to the first embodiment of the present application.

[0049] Figure 5 It is a structural schematic diagram after the first etching window and the second etching window are formed according to the first embodiment of the present application.

[0050] Figure 6is a structural schematic diagram of a structure after a first trench and a second trench are formed according to an embodiment of the present application.

[0051] Figure 7 is a structural schematic diagram of a structure after a first trench isolation structure and a second trench isolation structure are formed according to an embodiment of the present application.

[0052] Figure 8 is a structural schematic diagram of a structure after a first mask layer is formed according to an embodiment of the present application.

[0053] Figure 9 is a structural schematic diagram of a structure after a titanium oxide layer is formed according to an embodiment of the present application.

[0054] Figure 10 is a structural schematic diagram of a structure after a second mask layer is formed according to an embodiment of the present application.

[0055] Figure 11 is a structural schematic diagram of a structure after a first etching window, a second etching window and a third etching window are formed according to an embodiment of the present application.

[0056] Figure 12 is a structural schematic diagram of a structure after a first trench, a second trench and a third trench are formed according to an embodiment of the present application.

[0057] Figure 13 is a structural schematic diagram of a structure after a first trench isolation structure, a second trench isolation structure and a third trench isolation structure are formed according to an embodiment of the present application.

[0058] Figure 14 is a structural schematic diagram of a structure after a first etching window and a third etching window are formed according to an embodiment of the present application.

[0059] Figure 15 is a structural schematic diagram of a structure after a first trench isolation structure and a third trench isolation structure are formed according to an embodiment of the present application.

[0060] Figure 16 is a structural schematic diagram of a structure after a second mask layer is formed according to an embodiment of the present application.

[0061] Figure 17 is a structural schematic diagram of a structure after a first etching window, a second etching window and a third etching window are formed according to an embodiment of the present application.

[0062] Figure 18 is a structural schematic diagram of a structure after a first trench, a second trench and a third trench are formed according to an embodiment of the present application.

[0063] Explanation of reference signs:

[0064] 10 - substrate; 20 - oxide layer; 30 - titanium nitride layer; 31 - titanium oxide layer; 40 - first mask layer; 41 - first oxide window; 42 - second oxide window; 50 - second mask layer; 51 - first etching window; 52 - second etching window; 53 - third etching window; 61 - first trench; 62 - second trench; 63 - third trench; 71 - first trench isolation structure; 72 - second trench isolation structure; 73 - third trench isolation structure. DETAILED DESCRIPTION

[0065] In order to make the objects, advantages and features of the present application clearer, the following will further describe the present application in detail with reference to the accompanying drawings and specific embodiments. It should be noted that all the drawings are very simplified and not drawn according to scale, and are only used to facilitate and clarify the purpose of assisting the description of the embodiments of the present application. In addition, the structures shown in the drawings are often a part of the actual structures. In particular, the emphasis shown in each drawing is different, and sometimes different scales are used.

[0066] As used in the present application, the singular forms "a", "an" and "the" include plural referents unless the content clearly dictates otherwise. As used in the present application, the term "or" is generally employed in the sense as including "and / or" unless the content clearly dictates otherwise. As used in the present application, the term "several" is generally employed in the sense as including "at least one" unless the content clearly dictates otherwise. As used in the present application, the term "at least two" is generally employed in the sense as including "two or more" unless the content clearly dictates otherwise. In addition, the terms "first", "second", "third" are only used for the purpose of description, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined with "first", "second", "third" can explicitly or implicitly include one or at least two features.

[0067] Figure 1 is a flowchart of a trench manufacturing method provided by an embodiment of the present application. As shown in Figure 1 The trench manufacturing method provided by the embodiment includes the following steps:

[0068] Step S1: providing a substrate, and sequentially forming an oxide layer and a titanium nitride layer on the substrate;

[0069] Step S2: oxidizing the titanium nitride layer in different regions to different degrees, so that the titanium nitride layer with different thicknesses is oxidized to form a titanium oxide layer, and the thickness of the oxidized titanium nitride layer is greater than or equal to zero and less than or equal to the thickness of the titanium nitride layer; and

[0070] Step S3: etching the titanium oxide layer, or / and the titanium nitride layer and the oxide layer below the titanium nitride layer in each region and the substrate to form trenches with different depths.

[0071] In this embodiment, the titanium oxide layer is formed by oxidizing the titanium nitride layer in different regions to different degrees, that is, the titanium nitride layer in each region is oxidized to form a titanium oxide layer, the thickness of the titanium oxide layer formed in each region is different, the etching rate of the titanium nitride layer and the titanium oxide layer is different, the thicker the titanium oxide layer, the slower the etching, and the shallower the trench formed, thereby being able to form trenches with different depths in the same etching step.

[0072] Each region refers to a region in which a trench is to be formed, and the titanium nitride layer in the region in which a trench is to be formed is oxidized. The thickness of the oxidized titanium nitride layer is greater than or equal to zero and less than or equal to the thickness of the titanium nitride layer, that is, the titanium nitride layer in some regions can not be oxidized, and a trench with the deepest depth is formed in this region. The titanium nitride layer in some regions is fully oxidized to form a titanium oxide layer, and a trench with the shallowest depth is formed in this region. The thickness of the oxidized titanium nitride layer can be determined according to the depth of the trench to be formed, and the trench formed is between the deepest trench and the shallowest trench. The number of regions can be determined according to the number of trenches to be formed.

[0073] The present application will be described below through different embodiments.

[0074]

Embodiment One

[0075] Figures 2 to 7 is a schematic structural diagram of each step of the trench manufacturing method provided by Embodiment One of the present application. Next, the trench manufacturing method provided by Embodiment One of the present application will be described in detail in combination with Figure 1 、 Figures 2 to 7 the trench manufacturing method provided by Embodiment One of the present application.

[0076] In step S1, please refer to Figure 2 , a substrate 10 is provided, and an oxide layer 20 and a titanium nitride layer 30 are formed on the substrate 10 in sequence.

[0077] The material of the substrate 10 can be silicon, germanium, silicon germanium, silicon carbide, gallium arsenide, or indium gallium, etc., and can also be silicon on insulator or germanium on insulator; or can also be other materials, such as gallium arsenide and other III-V compounds. In this embodiment, the substrate 10 is a silicon substrate.

[0078] An oxide layer 20 and a titanium nitride layer 30 are sequentially formed on the substrate 10. The material of the oxide layer 20 includes but is not limited to silicon oxide, and the oxide layer 20 can be formed by any suitable process known to those skilled in the art, such as thermal oxidation, chemical vapor deposition (CVD), physical vapor deposition (PVD), atomic layer deposition (ALD), etc. The titanium nitride layer 30 can be formed by any suitable process known to those skilled in the art, such as chemical vapor deposition, physical vapor deposition, atomic layer deposition, etc.

[0079] In one embodiment, the oxide layer 20 and the titanium nitride layer 30 are formed by a chemical vapor deposition process. For example, the thickness of the oxide layer 20 is 100-500 nm, and the thickness of the titanium nitride layer 30 is 5-50 nm, but the present application is not limited thereto.

[0080] In step S2, as shown in Figures 3 to 5 the titanium nitride layer 30 in different regions is oxidized to different degrees, so that the titanium nitride layer 30 with different thicknesses is oxidized to form titanium oxide layers 31, and the thickness of the oxidized titanium nitride layer 30 is greater than or equal to zero and less than or equal to the thickness of the titanium nitride layer 30.

[0081] In step S3, as shown in Figure 6 the oxide layer 20 and the substrate 10 under the oxide layer 20 and the titanium nitride layer 30 in each region are sequentially etched to form trenches with different depths.

[0082] First, as shown in Figure 3 a first mask layer 40 is formed on the titanium nitride layer 30, and a first oxidation window 41 exposing the titanium nitride layer 30 is formed in the first mask layer 40.

[0083] In one embodiment, the first mask layer 40 is a photoresist layer. The photoresist layer is exposed and developed to form the first oxidation window 41 exposing the titanium nitride layer 30. The region of the titanium nitride layer 30 exposed by the first oxidation window 41 is the region where the trench is to be etched, and the trench formed in this region has the shallowest depth.

[0084] Next, as shown in Figure 3 the titanium nitride layer 30 is oxidized through the first oxidation window 41, so that the titanium nitride layer 30 under the first oxidation window 41 is completely oxidized to form a titanium oxide layer 31. For example, the titanium nitride layer 30 is oxidized by an inductively coupled low-temperature oxygen plasma or a reactive ion etching system, but the present application is not limited thereto.

[0085] In this embodiment, the titanium nitride layer 30 below the first oxidation window 41 is completely oxidized, and the titanium nitride layer 30 is entirely converted into a titanium oxide layer 31. The titanium nitride layer 30 in the remaining area covered by the first mask layer 40 remains unchanged.

[0086] Then, please refer to Figure 3 and Figure 4 As shown, the first mask layer 40 is removed, and a second mask layer 50 is formed on the titanium nitride layer 30 and the titanium oxide layer 31. In one embodiment, the second mask layer 50 is a photoresist layer.

[0087] Next, please refer to Figure 5 As shown, a first etching window 51 exposing the titanium oxide layer 31 and a second etching window 52 exposing the titanium nitride layer 30 are formed within the second mask layer 50. The first etching window 51 corresponds to the first oxide window 41, meaning the area exposed by the first etching window 51 is the same area previously exposed by the first oxide window 41, and the cross-sectional size of the first etching window 51 is equal to the cross-sectional size of the first oxide window 41. The first etching window 51 exposes the titanium oxide layer 31, while the second etching window 52 exposes the titanium nitride layer 30. The area exposed by the second etching window 52 is the region of the titanium nitride layer 30 that does not require oxidation, and the trenches formed in this region are the deepest trenches.

[0088] Next, please refer to Figure 5 and Figure 6 As shown, an etching process is performed using the second mask layer 50 as a mask. A first trench 61 is formed below the first etching window 51, penetrating the titanium oxide layer 31 and the oxide layer 20 and extending into the substrate 10. A second trench 62 is formed below the second etching window 52, ​​penetrating the titanium nitride layer 30 and the oxide layer 20 and extending into the substrate 10. The depth of the second trench 62 is greater than the depth of the first trench 61.

[0089] In one embodiment, the trenches are formed using dry etching. Exemplarily, the etching gas includes a mixture of CF4 and O2. The etching rate of titanium nitride is greater than that of titanium oxide, and the etching selectivity ratio of titanium oxide to titanium nitride is, for example, 1:10. Therefore, during etching using the second mask layer 50 as a mask, the etching time for the titanium oxide layer 31 exposed by the first etching window 51 is longer than the etching time for the titanium nitride layer 30 exposed by the second etching window 52. Consequently, the etching within the second etching window 52 first etches the substrate 10, and the depth of the second trench 62 is greater than the depth of the first trench 61, thereby forming trenches of different depths within the substrate 10 in the same etching process.

[0090] In one embodiment, the cross-sectional dimension of the second etching window 52 can be larger or smaller than the cross-sectional dimension of the first etching window 51, thereby making the cross-sectional dimension of the second trench 62 larger or smaller than the cross-sectional dimension of the first trench 61, i.e., forming two trenches with different depths and widths within the substrate 10. In another embodiment, the cross-sectional dimension of the second etching window 52 can also be equal to the cross-sectional dimension of the first etching window 51, making the cross-sectional dimension of the second trench 62 equal to the cross-sectional dimension of the first trench 61, i.e., forming two trenches with the same width but different depths within the substrate 10. The trench size can be determined according to actual needs.

[0091] In one embodiment, please refer to Figure 6 As shown, the longitudinal section of the trench is rectangular. In another embodiment, the longitudinal section of the trench can also be a trapezoid, wider at the top and narrower at the bottom. Of course, the longitudinal section of the trench can also be other shapes known to those skilled in the art, and the present invention does not limit this.

[0092] Please refer to Figure 6 and Figure 7 As shown, after forming the first trench 61 and the second trench 62, the method further includes: removing the second mask layer 50, and removing the titanium nitride layer 30 and the oxide layer 20. In one embodiment, the titanium nitride layer 30 can be removed using hydrogen peroxide (H2O2) solution or sulfuric acid (H2SO4) solution, and the oxide layer 20 can be removed using diluted hydrofluoric acid (HF).

[0093] Then, please refer to Figure 7 As shown, insulating material is filled into the first trench 61 and the second trench 62 to form a first trench isolation structure 71 and a second trench isolation structure 72. The insulating material is, for example, silicon oxide, and can be formed using any suitable process known to those skilled in the art, such as chemical vapor deposition, physical vapor deposition, or atomic layer deposition. The insulating material fills the first trench 61 and the second trench 62 and covers the substrate 10, and then planarization is performed to expose the substrate 10. The first trench isolation structure 71 is formed in the first trench 61, and the second trench isolation structure 72 is formed in the second trench 62.

[0094] In the trench manufacturing method provided by the embodiment, first, a substrate 10 is provided, and an oxide layer 20 and a titanium nitride layer 30 are sequentially formed on the substrate 10; then, the titanium nitride layer 30 in different regions is subjected to different degrees of oxidation, so that the titanium nitride layer 30 with different thicknesses is oxidized to form a titanium oxide layer 31, in the embodiment, the titanium nitride layer 30 in one region is completely oxidized to form the titanium oxide layer 31, and the titanium nitride layer 30 in another region is not oxidized; then, the titanium oxide layer 31 in the two regions, or the titanium nitride layer 30 and the oxide layer 20 and the substrate 10 thereunder are sequentially etched to form two-depth trenches. The titanium nitride layer 30 in one region is completely oxidized, and the titanium nitride layer 30 in another region is not oxidized, the etching rates of the titanium nitride layer 30 and the titanium oxide layer 31 are different, the thicker the titanium oxide layer 31 is, the slower the etching is, and the shallower the formed trench is, so that the first trench 61 and the second trench 62 with different depths can be formed in the same etching step.

[0095] Embodiment Two

[0096] The difference between the embodiment and the embodiment one is that while the first oxidation window 41 exposing the titanium nitride layer 30 is formed in the first mask layer 40, a second oxidation window is also formed in the first mask layer 40, and the depth of the second oxidation window is smaller than that of the first oxidation window 41. That is, in the embodiment, three trenches are formed, corresponding to the titanium nitride layer 30, the titanium nitride layer 30 in one region is completely oxidized to form the titanium oxide layer 31, the titanium nitride layer 30 in one region is partially oxidized, and the titanium nitride layer 30 in one region is not oxidized.

[0097] Figures 8 to 13 is a structural schematic diagram of each step of the trench manufacturing method provided by the embodiment two of the application. Next, the trench manufacturing method provided by the embodiment two of the application will be described in detail in combination with Figure 1 、 Figure 2 、 Figures 8 to 13 the trench manufacturing method provided by the embodiment two of the application.

[0098] Please refer to Figure 2 , an oxide layer 20 and a titanium nitride layer 30 are sequentially formed on the substrate 10.

[0099] Please refer to Figure 8As shown, a first mask layer 40 is formed on the titanium nitride layer 30, and a first oxidation window 41 exposing the titanium nitride layer 30 is formed in the first mask layer 40. Meanwhile, a second oxidation window 42 exposing the titanium nitride layer 30 is also formed in the first mask layer 40. The second oxidation window 42 has a smaller depth than the first oxidation window 41. The first oxidation window 41 and the second oxidation window 42 expose different regions of the titanium nitride layer 30, both of which are regions to be etched to form trenches. The region exposed by the first oxidation window 41 has the shallowest depth of the trenches formed therein, and the region exposed by the second oxidation window 42 has an increased depth of the trenches formed therein. In this embodiment, the material of the first mask layer 40 includes, but is not limited to, silicon oxide.

[0100] Please refer to Figure 9 As shown, the titanium nitride layer 30 is oxidized through the first oxidation window 41 and the second oxidation window 42, so that the titanium nitride layer 30 under the first oxidation window 41 is fully oxidized to form a titanium oxide layer 31, and part of the titanium nitride layer 30 under the second oxidation window 42 is oxidized to form the titanium oxide layer 31. Since the first oxidation window 41 exposes the titanium nitride layer 30, and part of the first mask layer 40 remains between the bottom of the second oxidation window 42 and the titanium nitride layer 30, during the oxidation process, the titanium nitride layer 30 under the first oxidation window 41 is fully oxidized, and only part of the titanium nitride layer 30 under the second oxidation window 42 is oxidized, so that the titanium oxide layer 31 formed still has part of the titanium nitride layer 30 under it.

[0101] In one embodiment, a photoresist layer (not shown) is formed on the first mask layer 40. The photoresist layer is exposed and developed to form a patterned photoresist layer using a half-tone mask or a step mask. The first mask layer 40 is etched using the patterned photoresist layer as a mask to form first oxidation windows 41 and second oxidation windows 42 with different depths in the first mask layer 40. The first oxidation windows 41 expose the titanium nitride layer 30, and the second oxidation windows 42 do not expose the titanium nitride layer 30. Then, the patterned photoresist layer is removed.

[0102] Please refer to Figure 9 With Figure 10 As shown, the first mask layer 40 is removed, and a second mask layer 50 is formed on the titanium nitride layer 30 and the titanium oxide layer 31. In this embodiment, the material of the second mask layer 50 includes, but is not limited to, silicon oxide.

[0103] Please refer to Figure 11As shown, a first etching window 51 exposing the titanium oxide layer 31 and a second etching window 52 exposing the titanium nitride layer 30 are formed in the second mask layer 50, and a third etching window 53 exposing the titanium oxide layer 31 is also formed in the second mask layer 50, the third etching window 53 corresponds to the second etching window 42, that is, the area exposed by the third etching window 53 is the area exposed by the second etching window 42, and the cross-sectional size of the third etching window 53 is equal to the cross-sectional size of the second etching window 42.

[0104] Please refer to Figure 12 As shown, a first etching window 51 exposing the titanium oxide layer 31 and a second etching window 52 exposing the titanium nitride layer 30 are formed in the second mask layer 50, and a third etching window 53 exposing the titanium oxide layer 31 is also formed in the second mask layer 50, the third etching window 53 corresponds to the second etching window 42, that is, the area exposed by the third etching window 53 is the area exposed by the second etching window 42, and the cross-sectional size of the third etching window 53 is equal to the cross-sectional size of the second etching window 42.

[0105] In an embodiment, the cross-sectional sizes of the first groove 61, the second groove 62 and the third groove 63 can be equal, that is, three grooves with the same width and different depths are formed in the substrate 10. In another embodiment, the cross-sectional sizes of the first groove 61, the second groove 62 and the third groove 63 are not equal, for example, the cross-sectional sizes of the second groove 62, the third groove 63 and the first groove 61 decrease in turn, so that three grooves with different depths and widths are formed in the substrate 10.

[0106] After the first groove 61, the second groove 62 and the third groove 63 are formed, the second mask layer 50 is removed, the titanium nitride layer 30 and the oxide layer 20 are removed, and the first groove isolation structure 71, the second groove isolation structure 72 and the third groove isolation structure 73 are formed by filling insulating materials in the first groove 61, the second groove 62 and the third groove 63, as shown in the structure. Figures 14 to 15

[0107] ​In the trench manufacturing method provided in the embodiment, first, a substrate 10 is provided, and an oxide layer 20 and a titanium nitride layer 30 are sequentially formed on the substrate 10; then, the titanium nitride layer 30 in different regions is subjected to different degrees of oxidation, so that the titanium nitride layer 30 with different thicknesses is oxidized to form a titanium oxide layer 31, in the embodiment, the titanium nitride layer 30 in one region is completely oxidized to form a titanium oxide layer 31, the titanium nitride layer 30 in another region is partially oxidized to form a titanium oxide layer 31, and the titanium nitride layer 30 in a third region is not oxidized; and then, the titanium oxide layer 31, the titanium nitride layer 30, the oxide layer 20 below the titanium nitride layer 30, and the substrate 10 in the three regions are sequentially etched to form trenches with three depths. In the embodiment, the titanium nitride layer 30 in one region is completely oxidized, the titanium nitride layer 30 with a partial thickness in another region is oxidized, and the titanium nitride layer 30 in a third region is not oxidized, the etching rates of the titanium nitride layer 30 and the titanium oxide layer 31 are different, the thicker the titanium oxide layer 31, the slower the etching, and the shallower the depth of the formed trench, so that the first trench 61, the second trench 62, and the third trench 63 with different depths can be formed in the same etching step.

[0108] On the basis of the embodiment, three oxidation windows with different thicknesses can be formed in the first mask layer 40, the titanium nitride layer 30 in the three regions is subjected to three degrees of oxidation through the three oxidation windows, and four trenches with different depths are finally formed together with the region in which the titanium nitride layer 30 is not oxidized. Of course, five or more trenches with different depths can also be formed.

[0109] Embodiment Three

[0110] The difference between the embodiment and Embodiment Two is that, after the first oxidation window 41 and the second oxidation window 42 are formed in the first mask layer 40 and are subjected to oxidation, the first mask layer 40 is not removed, and the etching process is directly performed with the first mask layer 40 as a mask.

[0111] Figure 1 is a structural schematic diagram of each step of the trench manufacturing method provided in Embodiment Three of the application. Next, the trench manufacturing method provided in Embodiment Three of the application will be described in detail in combination with Figure 2 , Figure 8 , Figure 9 and Figure 14 , Figure 15 and Figure 2 .

[0112] Please refer to Figure 8 , an oxide layer 20 and a titanium nitride layer 30 are sequentially formed on the substrate 10.

[0113] Please refer to Figure 9As shown, a first mask layer 40 is formed on the titanium nitride layer 30. Within the first mask layer 40, a first oxide window 41 is formed to expose the titanium nitride layer 30, and a second oxide window 42 is formed to not expose the titanium nitride layer 30. The depth of the second oxide window 42 is less than the depth of the first oxide window 41.

[0114] Please refer to Figure 9 As shown, the titanium nitride layer 30 is oxidized through the first oxidation window 41 and the second oxidation window 42, such that the titanium nitride layer 30 below the first oxidation window 41 is completely oxidized to form a titanium oxide layer 31, and the titanium nitride layer 30 with a partial thickness below the second oxidation window 42 is oxidized to form a titanium oxide layer 31.

[0115] Please refer to Figure 14 and Figure 15 As shown, an etching process is performed using the first mask layer 40 as a mask. A first trench 61 is formed below the first oxide window 41, penetrating the titanium oxide layer 31 and the oxide layer 20 and extending into the substrate 10. A third trench 63 is formed below the second oxide window 42, penetrating the titanium oxide layer 31, the titanium nitride layer 30 and the oxide layer 20 and extending into the substrate 10. The depth of the third trench 63 is greater than the depth of the first trench 61.

[0116] After forming the first trench 61 and the third trench 63, the method further includes: removing the first mask layer 40, removing the titanium nitride layer 30 and the oxide layer 20, and filling the first trench 61 and the third trench 63 with insulating material to form a first trench isolation structure 71 and a third trench isolation structure 73, forming as shown in the figure. Figures 16 to 18 The structure shown.

[0117] In the trench fabrication method provided in this embodiment, a substrate 10 is first provided, and an oxide layer 20 and a titanium nitride layer 30 are sequentially formed on the substrate 10. Then, the titanium nitride layer 30 in different regions is oxidized to different degrees, so that the titanium nitride layer 30 of different thicknesses is oxidized to form a titanium oxide layer 31. In this embodiment, the titanium nitride layer 30 in one region is completely oxidized to form a titanium oxide layer 31, and the titanium nitride layer 30 in another region is partially oxidized to form a titanium oxide layer 31. Afterwards, the titanium oxide layer 31, the titanium nitride layer 30 and the oxide layer 20 and the substrate 10 below the two regions are etched sequentially to form trenches of two depths. The present invention oxidizes the titanium nitride layer 30 in one region completely and oxidizes a portion of the titanium nitride layer 30 in another region. The etching rates of the titanium nitride layer 30 and the titanium oxide layer 31 are different. The thicker the titanium oxide layer 31, the slower the etching, and the shallower the trench formed. Thus, it is possible to form a first trench 61 and a third trench 63 of different depths in the same etching step.

[0118] In addition, a first oxide window 41 and a second oxide window 42 are formed in the first mask layer 40, and the titanium nitride layer 30 is oxidized. Then, the etching process is performed directly using the first mask layer 40 as a mask. Since the etching selectivity of titanium nitride and titanium oxide is relatively large, the first mask layer 40 retained at the bottom of the second oxide window 42 can be used to compensate for the thickness of the titanium oxide layer 31 at the bottom, which can reduce the etching selectivity and thus accurately control the etching depth.

[0119]

Example 4

[0120] The difference between this embodiment and Embodiment 3 is that, after forming the first oxidation window 41 and the second oxidation window 42 in the first mask layer 40 and performing oxidation, a second mask layer 50 is formed on the first mask layer 40. The second mask layer 50 covers the first mask layer 40 and fills the first oxidation window 41 and the second oxidation window 42. An etching window is formed in the second mask layer 50 and the first mask layer 40, and the etching process is performed using the second mask layer 50 and the first mask layer 40 as masks.

[0121] Figure 1 This is a schematic diagram of the steps involved in the trench fabrication method provided in Embodiment 4 of the present invention. Next, we will combine... Figure 2 , Figure 8 , Figure 9 and Figures 16 to 18 , Figure 13 as well as Figure 2 The method for manufacturing the trench provided in Embodiment 4 of the present invention will be described in detail.

[0122] Please refer to Figure 8As shown, an oxide layer 20 and a titanium nitride layer 30 are sequentially formed on the substrate 10.

[0123] As shown, a first mask layer 40 is formed on the titanium nitride layer 30, and a first oxidation window 41 exposing the titanium nitride layer 30 and a second oxidation window 42 not exposing the titanium nitride layer 30 are formed in the first mask layer 40. The depth of the second oxidation window 42 is less than the depth of the first oxidation window 41. Figure 9 As shown, a first mask layer 40 is formed on the titanium nitride layer 30, and a first oxidation window 41 exposing the titanium nitride layer 30 and a second oxidation window 42 not exposing the titanium nitride layer 30 are formed in the first mask layer 40. The depth of the second oxidation window 42 is less than the depth of the first oxidation window 41.

[0124] Figure 16 As shown, a first mask layer 40 is formed on the titanium nitride layer 30, and a first oxidation window 41 exposing the titanium nitride layer 30 and a second oxidation window 42 not exposing the titanium nitride layer 30 are formed in the first mask layer 40. The depth of the second oxidation window 42 is less than the depth of the first oxidation window 41.

[0125] As shown, a first mask layer 40 is formed on the titanium nitride layer 30, and a first oxidation window 41 exposing the titanium nitride layer 30 and a second oxidation window 42 not exposing the titanium nitride layer 30 are formed in the first mask layer 40. The depth of the second oxidation window 42 is less than the depth of the first oxidation window 41. Figure 9 As shown, a first mask layer 40 is formed on the titanium nitride layer 30, and a first oxidation window 41 exposing the titanium nitride layer 30 and a second oxidation window 42 not exposing the titanium nitride layer 30 are formed in the first mask layer 40. The depth of the second oxidation window 42 is less than the depth of the first oxidation window 41.

[0126] Figure 16 As shown, a first mask layer 40 is formed on the titanium nitride layer 30, and a first oxidation window 41 exposing the titanium nitride layer 30 and a second oxidation window 42 not exposing the titanium nitride layer 30 are formed in the first mask layer 40. The depth of the second oxidation window 42 is less than the depth of the first oxidation window 41. Figure 17 Figure 18 As shown, a first mask layer 40 is formed on the titanium nitride layer 30, and a first oxidation window 41 exposing the titanium nitride layer 30 and a second oxidation window 42 not exposing the titanium nitride layer 30 are formed in the first mask layer 40. The depth of the second oxidation window 42 is less than the depth of the first oxidation window 41.

[0127] As shown, a first mask layer 40 is formed on the titanium nitride layer 30, and a first oxidation window 41 exposing the titanium nitride layer 30 and a second oxidation window 42 not exposing the titanium nitride layer 30 are formed in the first mask layer 40. The depth of the second oxidation window 42 is less than the depth of the first oxidation window 41. Figure 13 As shown, a first mask layer 40 is formed on the titanium nitride layer 30, and a first oxidation window 41 exposing the titanium nitride layer 30 and a second oxidation window 42 not exposing the titanium nitride layer 30 are formed in the first mask layer 40. The depth of the second oxidation window 42 is less than the depth of the first oxidation window 41.

[0128] ​​​After forming the first trench 61, the second trench 62 and the third trench 63, the method further comprises: removing the second mask layer 50 and the first mask layer 40, removing the titanium nitride layer 30 and the oxide layer 20, filling insulating material in the first trench 61, the second trench 62 and the third trench 63 to form a first trench isolation structure 71, a second trench isolation structure 72 and a third trench isolation structure 73, thereby forming a structure as shown in ​

[0129] In the method for forming trenches provided in the embodiment, first, a substrate 10 is provided, and an oxide layer 20 and a titanium nitride layer 30 are formed on the substrate 10 in sequence; then, the titanium nitride layer 30 in different regions is oxidized to different degrees, so that the titanium nitride layer 30 with different thicknesses is oxidized to form a titanium oxide layer 31, in the embodiment, the titanium nitride layer 30 in one region is completely oxidized to form a titanium oxide layer 31, the titanium nitride layer 30 in another region is partially oxidized to form a titanium oxide layer 31, and the titanium nitride layer 30 in a third region is not oxidized; then, the titanium oxide layer 31, the titanium nitride layer 30, the oxide layer 20 below the titanium nitride layer 30 and the substrate 10 in the three regions are etched to form trenches with three depths. In the method, the titanium nitride layer 30 in one region is completely oxidized, the titanium nitride layer 30 with a partial thickness in another region is oxidized, and the titanium nitride layer 30 in a third region is not oxidized, the etching rates of the titanium nitride layer 30 and the titanium oxide layer 31 are different, the thicker the titanium oxide layer 31 is, the slower the etching is, and the shallower the formed trench is, thereby being capable of forming the first trench 61, the second trench 62 and the third trench 63 with different depths in the same etching step.

[0130] In addition, in the embodiment, the first mask layer 40 does not need to be removed, and the second mask layer 50 is directly formed on the first mask layer 40, thereby saving a step of removing a mask layer.

[0131] ​In summary, in the trench manufacturing method provided by the application, a substrate is provided, and an oxidation layer and a titanium nitride layer are sequentially formed on the substrate; then the titanium nitride layers in different regions are oxidized to different degrees, so that the titanium nitride layers with different thicknesses are oxidized to form titanium oxide layers, and the thickness of the oxidized titanium nitride layer is greater than or equal to zero and less than or equal to the thickness of the titanium nitride layer; then the oxidation layers, the titanium nitride layers, and the substrates under the oxidation layers and the titanium nitride layers in each region are sequentially etched to form trenches with different depths. In the application, the titanium nitride layers in different regions are oxidized to different degrees, so that the titanium nitride layers with different thicknesses are oxidized to form titanium oxide layers, that is, the thicknesses of the titanium oxide layers formed in different regions are different, the etching rates of the titanium nitride layers and the titanium oxide layers are different, the thicker the titanium oxide layer, the slower the etching, and the shallower the formed trench, so that trenches with different depths can be formed in the same etching step.

[0132] Further, the cross-sectional sizes of the first oxidation window and the second oxidation window are different, and / or the cross-sectional sizes of the first etching window, the second etching window, and the third etching window are different, so that trenches with different widths and different depths can be formed.

[0133] Further, the first oxidation window and the second oxidation window are formed in the first mask layer, the titanium nitride layer is oxidized, and then the etching process is directly performed with the first mask layer as a mask. Since the etching selectivity ratio of titanium nitride and titanium oxide is relatively large, the first mask layer reserved at the bottom of the second oxidation window compensates the thickness of the titanium oxide layer at the bottom, reduces the etching selectivity ratio, and thus the etching depth is accurately controlled.

[0134] It should be noted that the embodiments in the specification are described in a progressive manner, and the manufacturing methods described later mainly explain the differences from the manufacturing methods described earlier. The same and similar parts between the embodiments can be referred to.

[0135] The above description is only a description of the preferred embodiments of the application, and does not limit the scope of the application in any way. Any modification or modification of the application by a person skilled in the art according to the above disclosure is within the protection scope of the claims.

Claims

1. A method for manufacturing a trench, characterized in that, Includes the following steps: A substrate is provided on which an oxide layer and a titanium nitride layer are sequentially formed; The titanium nitride layer in different regions is oxidized to different degrees, so that the titanium nitride layer of different thicknesses is oxidized to form titanium oxide layer, and the thickness of the oxidized titanium nitride layer is greater than or equal to zero and less than or equal to the thickness of the titanium nitride layer. The titanium nitride layer of different thickness in each region is oxidized, and the thickness of the titanium oxide layer formed is different. as well as The titanium oxide layer and / or the titanium nitride layer in each region, as well as the oxide layer below it and the substrate, are etched sequentially to form trenches of different depths.

2. The method for manufacturing a trench according to claim 1, characterized in that, Methods for oxidizing the titanium nitride layer in different regions to different degrees and etching it to form trenches of different depths include: A first mask layer is formed on the titanium nitride layer, and a first oxide window exposing the titanium nitride layer is formed within the first mask layer; The titanium nitride layer is oxidized through the first oxidation window, so that the titanium nitride layer below the first oxidation window is completely oxidized to form a titanium oxide layer. Remove the first mask layer and form a second mask layer on the titanium nitride layer and the titanium oxide layer; A first etching window exposing the titanium oxide layer and a second etching window exposing the titanium nitride layer are formed within the second mask layer; Using the second mask layer as a mask, an etching process is performed. A first trench is formed below the first etching window, penetrating the titanium oxide layer and the oxide layer and extending into the substrate. A second trench is formed below the second etching window, penetrating the titanium nitride layer and the oxide layer and extending into the substrate. The depth of the second trench is greater than the depth of the first trench. Remove the second mask layer.

3. The method for manufacturing a trench according to claim 2, characterized in that, The first mask layer and the second mask layer are photoresist layers.

4. The method for manufacturing a trench according to claim 2, characterized in that, While forming a first oxide window exposing the titanium nitride layer within the first mask layer, a second oxide window is also formed within the first mask layer, the depth of the second oxide window being less than the depth of the first oxide window.

5. The method for manufacturing a trench according to claim 4, characterized in that, While the titanium nitride layer is oxidized through the first oxidation window, the titanium nitride layer is also oxidized through the second oxidation window, so that a portion of the titanium nitride layer below the second oxidation window is oxidized to form a titanium oxide layer. While forming the first etching window and the second etching window in the second mask layer, a third etching window that exposes the titanium oxide layer is also formed in the second mask layer, and the third etching window corresponds to the second oxide window; During the etching process using the second mask layer as a mask, a third trench is formed below the third etching window, penetrating the titanium oxide layer, the titanium nitride layer, and the oxide layer and extending to the substrate. The depth of the third trench is less than the depth of the second trench but greater than the depth of the first trench.

6. The method for manufacturing a trench according to claim 1, characterized in that, Methods for oxidizing the titanium nitride layer in different regions to different degrees and etching it to form trenches of different depths include: A first mask layer is formed on the titanium nitride layer, and a first oxide window exposing the titanium nitride layer and a second oxide window not exposing the titanium nitride layer are formed within the first mask layer; The titanium nitride layer is oxidized through the first oxidation window and the second oxidation window, so that the titanium nitride layer below the first oxidation window is completely oxidized to form a titanium oxide layer, and the titanium nitride layer with a certain thickness below the second oxidation window is oxidized to form a titanium nitride layer. Using the first mask layer as a mask, an etching process is performed to form a first trench below the first oxide window, penetrating the titanium oxide layer and the oxide layer and extending into the substrate. A third trench is formed below the second oxide window, penetrating the titanium oxide layer, the titanium nitride layer, and the oxide layer and extending into the substrate. The depth of the third trench is greater than the depth of the first trench. Remove the first mask layer.

7. The method for manufacturing a trench according to claim 1, characterized in that, Methods for oxidizing the titanium nitride layer in different regions to different degrees and etching it to form trenches of different depths include: A first mask layer is formed on the titanium nitride layer, and a first oxide window exposing the titanium nitride layer and a second oxide window not exposing the titanium nitride layer are formed within the first mask layer; The titanium nitride layer is oxidized through the first oxidation window and the second oxidation window, so that the titanium nitride layer below the first oxidation window is completely oxidized to form a titanium oxide layer, and the titanium nitride layer with a certain thickness below the second oxidation window is oxidized to form a titanium nitride layer. A second mask layer is formed on the first mask layer, the second mask layer covering the first mask layer and filling the first oxidation window and the second oxidation window; A first etching window that exposes the titanium oxide layer and corresponds to the first oxidation window and a third etching window that exposes the titanium oxide layer and corresponds to the second oxidation window are formed in the second mask layer and the first mask layer, and a second etching window that exposes the titanium nitride layer is also formed. An etching process is performed using the second mask layer and the first mask layer as masks. A first trench is formed below the first etching window, penetrating the titanium oxide layer and the oxide layer and extending into the substrate. A second trench is formed below the second etching window, penetrating the titanium nitride layer and the oxide layer and extending into the substrate. A third trench is formed below the third etching window, penetrating the titanium oxide layer, the titanium nitride layer, and the oxide layer and extending into the substrate. The depth of the second trench is greater than the depth of the first trench, and the depth of the third trench is greater than the depth of the first trench but less than the depth of the second trench. Remove the second mask layer and the first mask layer.

8. The method for manufacturing a trench according to claim 4, 6, or 7, characterized in that, The materials of the first mask layer and the second mask layer include silicon oxide; The method for forming the first oxide window and the second oxide window within the first mask layer includes: A photoresist layer is formed on the first mask layer; The photoresist layer is exposed and developed using a halftone mask or a step mask to form a patterned photoresist layer; Using the patterned photoresist layer as a mask, the first mask layer is etched to form first oxide windows and second oxide windows of different depths within the first mask layer; and Remove the patterned photoresist layer.

9. The method for manufacturing a trench according to claim 5 or 7, characterized in that, The first oxidation window and the second oxidation window have different cross-sectional dimensions; and / or, the first etching window, the second etching window and the third etching window have different cross-sectional dimensions.

10. The method for manufacturing a trench according to claim 1, characterized in that, After forming the trench, the process further includes removing the titanium nitride layer and the oxide layer.

Images