Manufacturing method of groove

Abstract

The invention provides a trench manufacturing method, which comprises the following steps of: providing a substrate, and sequentially forming an oxide layer and a titanium nitride layer on the substrate; the titanium nitride layers in the different areas 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 layers is larger than or equal to zero and smaller than or equal to the thickness of the titanium nitride layers; and etching the titanium oxide layer or / and the titanium nitride layer in each region, the oxide layer below the titanium nitride layer and the substrate in sequence to form grooves with different depths. According to the method, the titanium nitride layers in different areas are oxidized to different degrees, so that the titanium nitride layers with different thicknesses are oxidized to form the titanium oxide layers, namely, the thicknesses of the titanium oxide layers formed in the areas are different, the etching rates of the titanium nitride layers and the titanium oxide layers are different, and the thicker the titanium oxide layers are, the slower the etching is; the depth of the formed groove is shallower, so that grooves with different depths can be formed in the same etching step.

Description

Technical Field

[0001] The present invention relates to the technical field of semiconductor integrated circuits, and in particular to a method for manufacturing a trench. Background Art

[0002] In the manufacture of advanced semiconductor devices, precise control of multi-level trench structures is crucial for achieving high performance. Traditionally, trenches of varying depths require multiple mask deposition, photolithography, and etching steps. This results in a complex process flow, long cycle times, high costs, and cumulative overlay errors. For example, a dual-trench structure requires two separate masking and etching steps. This cumulative overlay error reduces the control accuracy of trench depth and width.

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

[0004] Therefore, there is an urgent need for a manufacturing method that can simultaneously achieve multi-level groove depth differentiation. Summary of the Invention

[0005] The object of the present invention is to provide a method for manufacturing a groove, which can form grooves of different depths in one etching process.

[0006] To solve the above technical problems, the present invention provides a method for manufacturing a groove, comprising the following steps: providing a substrate, and sequentially forming an oxide layer and a titanium nitride layer on the substrate; Oxidizing different areas of the titanium nitride layer to different degrees, so that the titanium nitride layer of 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; and The titanium oxide layer and / or the titanium nitride layer in each region and the oxide layer and the substrate thereunder are etched in sequence to form grooves of different depths.

[0007] Optionally, the method of oxidizing the titanium nitride layer in different regions to different degrees and etching to form grooves of different depths includes: forming a first mask layer on the titanium nitride layer, and forming a first oxidation window exposing the titanium nitride layer in the first mask layer; oxidizing the titanium nitride layer 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; removing the first mask layer and forming a second mask layer on the titanium nitride layer and the titanium oxide layer; 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; performing an etching process using the second mask layer as a mask to form a first trench below the first etching window, which penetrates the titanium oxide layer and the oxide layer and extends into the substrate; and forming a second trench below the second etching window, which penetrates the titanium nitride layer and the oxide layer and extends into the substrate, wherein the depth of the second trench is greater than the depth of the first trench; and The second mask layer is removed.

[0008] Optionally, the first mask layer and the second mask layer are photoresist layers.

[0009] Optionally, while forming a first oxidation window exposing the titanium nitride layer in the first mask layer, a second oxidation window is also formed in the first mask layer, and a depth of the second oxidation window is smaller than a depth of the first oxidation window.

[0010] 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 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 exposing the titanium oxide layer is also formed in the second mask layer, wherein the third etching window corresponds to the second etching window; During the etching process using the second mask layer as a mask, a third trench is formed below the third etching window, which penetrates the titanium oxide layer, the titanium nitride layer and the oxide layer and extends to the substrate. The depth of the third trench is less than the depth of the second trench and greater than the depth of the first trench.

[0011] Optionally, the method of oxidizing the titanium nitride layer in different regions to different degrees and etching to form grooves of different depths includes: 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; oxidizing the titanium nitride layer 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 a portion of the titanium nitride layer below the second oxidation window is oxidized to form a titanium nitride layer; performing an etching process using the first mask layer as a mask to form a first trench below the first oxidation window, the trench penetrating the titanium oxide layer and the oxide layer and extending into the substrate; and forming a third trench below the second oxidation window, the trench penetrating the titanium oxide layer, the titanium nitride layer, and the oxide layer and extending into the substrate, wherein the depth of the third trench is greater than the depth of the first trench; and The first mask layer is removed.

[0012] Optionally, the method of oxidizing the titanium nitride layer in different regions to different degrees and etching to form grooves of different depths includes: 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; oxidizing the titanium nitride layer 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 a portion of the titanium nitride layer below the second oxidation window is oxidized to form a titanium nitride layer; forming a second mask layer on the first mask layer, wherein the second mask layer covers the first mask layer and fills the first oxidation window and the second oxidation window; 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 in the second mask layer and forming a second etching window exposing the titanium nitride layer; An etching process is performed using the second mask layer and the first mask layer as masks, forming a first trench below the first etching window that penetrates the titanium oxide layer and the oxide layer and extends into the substrate, forming a second trench below the second etching window that penetrates the titanium nitride layer and the oxide layer and extends into the substrate, and forming a third trench below the third etching window that penetrates the titanium oxide layer, the titanium nitride layer, and the oxide layer and extends 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; and The second mask layer and the first mask layer are removed.

[0013] Optionally, the material of the first mask layer and the second mask layer includes silicon oxide; The method of forming a first oxidation window and a second oxidation window in the first mask layer includes: forming a photoresist layer on the first mask layer; exposing the photoresist layer using a half-tone mask or a step mask and developing the photoresist layer to form a patterned photoresist layer; Using the patterned photoresist layer as a mask, etching the first mask layer to form a first oxidation window and a second oxidation window of different depths in the first mask layer; and The patterned photoresist layer is removed.

[0014] Optionally, the cross-sectional dimensions of the first oxidation window and the second oxidation window are different; and / or the cross-sectional dimensions of the first etching window, the second etching window and the third etching window are different.

[0015] Optionally, after forming the trench, the method further includes: removing the titanium nitride layer and the oxide layer.

[0016] In summary, in the method for making a groove provided by the present invention, a substrate is first provided, and an oxide 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 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; then, the titanium oxide layer in each region, or / and the titanium nitride layer and the oxide layer thereunder and the substrate are sequentially etched to form grooves of different depths. The present invention performs different degrees of oxidation on the titanium nitride layer in different regions, so that the titanium nitride layer of 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, and the etching rate of the titanium nitride layer and the titanium oxide layer is different. The thicker the titanium oxide layer, the slower it is etched, and the shallower the depth of the formed groove is, thereby being able to form grooves of different depths in the same etching step.

[0017] Furthermore, the cross-sectional dimensions of the first oxidation window and the second oxidation window are different, and / or the cross-sectional dimensions of the first etching window, the second etching window and the third etching window are different, thereby forming grooves of different widths and depths.

[0018] Furthermore, a first oxidation window and a second oxidation window are formed in the first mask layer, and the titanium nitride layer is oxidized. Then, an etching process is performed directly using the first mask layer as a mask. Since the etching selectivity ratio of titanium nitride to titanium oxide is relatively large, the thickness of the titanium oxide layer at the bottom is compensated by the first mask layer retained at the bottom of the second oxidation window, thereby lowering the etching selectivity and accurately controlling the etching depth. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 4 is a flow chart of a method for manufacturing a groove provided by an embodiment of the present invention.

[0020] Figure 2 It is a schematic diagram of the structure after the titanium nitride layer is formed provided in the first embodiment of the present invention.

[0021] Figure 3 It is a schematic diagram of the structure after the titanium oxide layer is formed provided in the first embodiment of the present invention.

[0022] Figure 4 It is a schematic diagram of the structure after the second mask layer is formed provided in the first embodiment of the present invention.

[0023] Figure 5 It is a structural diagram after forming the first etching window and the second etching window provided in the first embodiment of the present invention.

[0024] Figure 6 It is a schematic diagram of the structure after the first trench and the second trench are formed, provided in the first embodiment of the present invention.

[0025] Figure 7 It is a structural schematic diagram after forming the first trench isolation structure and the second trench isolation structure provided in the first embodiment of the present invention.

[0026] Figure 8 It is a schematic diagram of the structure after the first mask layer is formed provided by the second embodiment of the present invention.

[0027] Figure 9 It is a schematic diagram of the structure after the titanium oxide layer is formed provided by the second embodiment of the present invention.

[0028] Figure 10 It is a schematic structural diagram after the second mask layer is formed according to the second embodiment of the present invention.

[0029] Figure 11 It is a structural diagram after forming the first etching window, the second etching window and the third etching window provided in the second embodiment of the present invention.

[0030] Figure 12 It is a schematic diagram of the structure after the first trench, the second trench and the third trench are formed, provided in the second embodiment of the present invention.

[0031] Figure 13 It is a structural schematic diagram after forming the first trench isolation structure, the second trench isolation structure and the third trench isolation structure provided in the second embodiment of the present invention.

[0032] Figure 14 It is a schematic diagram of the structure after the first etching window and the third etching window are formed, as provided in the third embodiment of the present invention.

[0033] Figure 15 It is a structural diagram after forming the first trench isolation structure and the third trench isolation structure provided in the third embodiment of the present invention.

[0034] Figure 16 It is a schematic diagram of the structure after the second mask layer is formed provided by the fourth embodiment of the present invention.

[0035] Figure 17 It is a structural diagram after forming the first etching window, the second etching window and the third etching window provided in the fourth embodiment of the present invention.

[0036] Figure 18 This is a schematic diagram of the structure after the first trench, the second trench, and the third trench are formed, as provided in the fourth embodiment of the present invention.

[0037] Description of reference numerals: 10-substrate; 20-oxide layer; 30-titanium nitride layer; 31-titanium oxide layer; 40-first mask layer; 41-first oxidation window; 42-second oxidation 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

[0038] To make the objects, advantages, and features of the present invention more clearly apparent, the present invention is further described below in conjunction with the accompanying drawings and specific embodiments. It should be noted that the drawings are all in a very simplified form and are not drawn to scale. They are only used to conveniently and clearly assist in illustrating the purposes of the embodiments of the present invention. In addition, the structures shown in the drawings are often part of the actual structure. In particular, different drawings may need to illustrate different focuses and sometimes use different scales.

[0039] As used in the present invention, the singular forms "a", "an" and "the" include plural objects, unless the content clearly indicates otherwise. As used in the present invention, the term "or" is generally used in a sense including "and / or", unless the content clearly indicates otherwise. As used in the present invention, the term "several" is generally used in a sense including "at least one", unless the content clearly indicates otherwise. As used in the present invention, the term "at least two" is generally used in a sense including "two or more", unless the content clearly indicates otherwise. In addition, the terms "first", "second" and "third" are used for descriptive purposes only and are not to be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first", "second" and "third" may explicitly or implicitly include one or at least two of the features.

[0040] Figure 1This is a flow chart of a method for making a groove according to an embodiment of the present invention. Figure 1 As shown, the method for manufacturing the groove provided in this embodiment includes the following steps: Step S1: providing a substrate, and sequentially forming an oxide layer and a titanium nitride layer on the substrate; Step S2: oxidizing the titanium nitride layer in different regions to different degrees, so that the titanium nitride layer of 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; and Step S3: etching the titanium oxide layer and / or the titanium nitride layer in each region and the oxide layer and the substrate thereunder in sequence to form grooves of different depths.

[0041] In this embodiment, the titanium nitride layer in different areas is oxidized to different degrees, so that the titanium nitride layers of different thicknesses are oxidized to form titanium oxide layers, that is, the titanium nitride layers of different thicknesses in each area are oxidized, and the thicknesses of the titanium oxide layers formed in each area are different. The etching rates of the titanium nitride layer and the titanium oxide layer are different. The thicker the titanium oxide layer, the slower it is etched, and the depth of the formed groove is shallower, thereby forming grooves of different depths in the same etching step.

[0042] Each region refers to a region where a groove is predetermined to be formed, and the titanium nitride layer within the region where the groove is 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 may not be oxidized, and the deepest groove is formed in this region. The titanium nitride layer in some regions is completely oxidized to form a titanium oxide layer, and the shallowest groove is formed in this region. The titanium nitride layer in the remaining regions may be partially oxidized to form a titanium oxide layer. The thickness of the oxidized titanium nitride layer can be determined based on the actual depth of the groove to be formed, and the groove formed is between the deepest groove and the shallowest groove. The number of regions can be determined based on the number of grooves to be formed.

[0043] The present application is described below through different embodiments.

[0044] [Example 1] Figures 2 to 7 This is a schematic diagram of the structure of each step of the groove manufacturing method provided in the first embodiment of the present invention. Figure 1 、 Figures 2 to 7 The method for manufacturing the groove provided in the first embodiment of the present invention is described in detail.

[0045] In step S1, please refer to Figure 2 As shown, a substrate 10 is provided, and an oxide layer 20 and a titanium nitride layer 30 are sequentially formed on the substrate 10 .

[0046] The substrate 10 may be made of silicon, germanium, silicon germanium, silicon carbide, gallium arsenide, or indium gallium, or may be silicon-on-insulator (SOI) or germanium-on-insulator (GOI). Alternatively, the substrate 10 may be made of other materials, such as III-V compounds such as gallium arsenide. In this embodiment, the substrate 10 is a silicon substrate.

[0047] An oxide layer 20 and a titanium nitride layer 30 are sequentially formed on the substrate 10. The oxide layer 20 may be made of, but not limited to, silicon oxide and may be formed using any suitable process known to those skilled in the art, such as thermal oxidation, chemical vapor deposition (CVD), physical vapor deposition (PVD), or atomic layer deposition (ALD). The titanium nitride layer 30 may 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.

[0048] In one embodiment, the oxide layer 20 and the titanium nitride layer 30 are formed by chemical vapor deposition. For example, the thickness of the oxide layer 20 is 100 nm to 500 nm, and the thickness of the titanium nitride layer 30 is 5 nm to 50 nm, but the present invention is not limited thereto.

[0049] In step S2, please refer to Figures 3 to 5 As shown, 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, 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.

[0050] In step S3, please refer to Figure 6 As shown, the titanium oxide layer 31 and / or the titanium nitride layer 30 in each region and the oxide layer 20 and the substrate 10 thereunder are sequentially etched to form grooves of different depths.

[0051] First, please refer to Figure 3 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 is formed in the first mask layer 40 .

[0052] In one embodiment, the first mask layer 40 is a photoresist layer. The photoresist layer is exposed and developed to form a first oxidation window 41 exposing the titanium nitride layer 30. The area of ​​the titanium nitride layer 30 exposed by the first oxidation window 41 is the area where the trench is to be etched, and the depth of the trench formed in this area is the shallowest.

[0053] Next, please continue to refer to Figure 3As shown, the titanium nitride layer 30 is oxidized through the first oxidation window 41, so that the titanium nitride layer 30 below the first oxidation window 41 is completely oxidized to form a titanium oxide layer 31. Exemplarily, the titanium nitride layer 30 is oxidized by an inductively coupled low-temperature oxygen plasma or a reactive ion etching system, but is certainly not limited thereto.

[0054] In this embodiment, the titanium nitride layer 30 below the first oxidation window 41 is completely oxidized and 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.

[0055] 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.

[0056] Afterwards, 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 in the second mask layer 50. The first etching window 51 corresponds to the first oxidation window 41, that is, the area exposed by the first etching window 51 is the area previously exposed by the first oxidation window 41, and the cross-sectional size of the first etching window 51 is equal to the cross-sectional size of the first oxidation 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 area of ​​the titanium nitride layer 30 that does not need to be oxidized, and the trench formed in this area is the deepest trench.

[0057] 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, and a first groove 61 is formed below the first etching window 51, which penetrates the titanium oxide layer 31 and the oxide layer 20 and extends into the substrate 10. A second groove 62 is formed below the second etching window 52, ​​which penetrates the titanium nitride layer 30 and the oxide layer 20 and extends into the substrate 10. The depth of the second groove 62 is greater than the depth of the first groove 61.

[0058] In one embodiment, dry etching is used to form the groove. Exemplarily, the etching gas includes a mixture of CF4 and O2. The etching rate of titanium nitride is greater than the etching rate of titanium oxide, and the etching selectivity ratio of titanium oxide to titanium nitride is, for example, 1:10. Therefore, in the process of etching using the second mask layer 50 as a mask, the time for etching the titanium oxide layer 31 exposed by the first etching window 51 is longer than the time for etching the titanium nitride layer 30 exposed by the second etching window 52. Therefore, the etching in the second etching window 52 etches the substrate 10 first, and the depth of the second groove 62 is greater than the depth of the first groove 61, thereby forming grooves of different depths in the substrate 10 in the same etching process.

[0059] In one embodiment, the cross-sectional dimensions of the second etch window 52 may be larger or smaller than the cross-sectional dimensions of the first etch window 51, thereby making the cross-sectional dimensions of the second trench 62 larger or smaller than the cross-sectional dimensions of the first trench 61, i.e., forming two trenches of different depths and widths in the substrate 10. In another embodiment, the cross-sectional dimensions of the second etch window 52 may be equal to the cross-sectional dimensions of the first etch window 51, thereby making the cross-sectional dimensions of the second trench 62 equal to the cross-sectional dimensions of the first trench 61, i.e., forming two trenches of the same width but different depths in the substrate 10. The dimensions of the trenches may be determined according to actual needs.

[0060] In one embodiment, please refer to Figure 6 As shown, the longitudinal section of the groove is a rectangle. In another embodiment, the longitudinal section of the groove can also be a trapezoid that is wide at the top and narrow at the bottom. Of course, the longitudinal section of the groove can also be other shapes known to those skilled in the art, and the present invention is not limited thereto.

[0061] Please refer to Figure 6 and Figure 7 As shown, after forming the first trench 61 and the second trench 62, the process 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 a hydrogen peroxide (H2O2) solution or a sulfuric acid (H2SO4) solution, and the oxide layer 20 can be removed using diluted hydrofluoric acid (HF).

[0062] Then, please refer to Figure 7As shown, an insulating material is filled in 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 by any suitable process known to those skilled in the art, such as a chemical vapor deposition process, a physical vapor deposition process, an atomic layer deposition process, etc. The insulating material fills the first trench 61 and the second trench 62 and covers the substrate 10, and then is planarized until the substrate 10 is exposed. A first trench isolation structure 71 is formed in the first trench 61, and a second trench isolation structure 72 is formed in the second trench 62.

[0063] In the groove 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 layers 30 of different thicknesses are oxidized to form titanium oxide layers 31. In this 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 the other 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 thereunder, and the substrate 10 are sequentially etched to form grooves of two depths. The present invention completely oxidizes the titanium nitride layer 30 in one area and does not oxidize the titanium nitride layer 30 in another area. 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 it is etched, and the depth of the formed groove is shallower. Therefore, the first groove 61 and the second groove 62 of different depths can be formed in the same etching step.

[0064] [Example 2] The difference between this embodiment and the first embodiment is that, while a 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 less than the depth of the first oxidation window 41. That is, in this embodiment, three trenches are formed, corresponding to the titanium nitride layer 30: one region of the titanium nitride layer 30 is completely oxidized to form the titanium oxide layer 31, another region of the titanium nitride layer 30 is partially oxidized, and another region of the titanium nitride layer 30 is not oxidized.

[0065] Figures 8 to 13 This is a schematic diagram of the structure of each step of the groove manufacturing method provided by the second embodiment of the present invention. Figure 1 、 Figure 2 、 Figures 8 to 13 The method for manufacturing the groove provided in the second embodiment of the present invention is described in detail.

[0066] Please refer to Figure 2 As shown, an oxide layer 20 and a titanium nitride layer 30 are sequentially formed on the substrate 10 .

[0067] Please refer to Figure 8 As shown, a first mask layer 40 is formed on the titanium nitride layer 30, and a first oxidation window 41 is formed in the first mask layer 40 to expose the titanium nitride layer 30. A second oxidation window 42 is also formed. The second oxidation window 42 exposes the titanium nitride layer 30, and the depth of the second oxidation window 42 is less than the depth of the first oxidation window 41. The first oxidation window 41 and the second oxidation window 42 expose different areas of the titanium nitride layer 30. Both areas are areas where trenches need to be etched. The depth of the trench formed in the area exposed by the first oxidation window 41 is the shallowest, while the depth of the trench formed in the area exposed by the second oxidation window 42 is greater. In this embodiment, the material of the first mask layer 40 includes, but is not limited to, silicon oxide.

[0068] 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 below the first oxidation window 41 is completely oxidized to form a titanium oxide layer 31, and the partial thickness of the titanium nitride layer 30 below the second oxidation window 42 is oxidized to form a titanium oxide layer 31. Because the first oxidation window 41 exposes the titanium nitride layer 30, and a partial thickness 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 below the first oxidation window 41 is completely oxidized, while only a partial thickness of the titanium nitride layer 30 below the second oxidation window 42 is oxidized, resulting in a partial thickness of the titanium nitride layer 30 still below the formed titanium oxide layer 31.

[0069] In one embodiment, a photoresist layer (not shown) is formed on the first mask layer 40, and the photoresist layer is exposed and developed using a half-tone mask or a step mask to form a patterned photoresist layer. The first mask layer 40 is etched using the patterned photoresist layer as a mask to form a first oxidation window 41 and a second oxidation window 42 of different depths in the first mask layer 40, wherein the first oxidation window 41 exposes the titanium nitride layer 30, and the second oxidation window 42 does not expose the titanium nitride layer 30, and then the patterned photoresist layer is removed.

[0070] Please refer to Figure 9 and Figure 10As 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.

[0071] Please refer to Figure 11 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. At the same time, 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 oxidation window 42, that is, the area exposed by the third etching window 53 is the area previously exposed by the second oxidation window 42, and the cross-sectional size of the third etching window 53 is equal to the cross-sectional size of the second oxidation window 42.

[0072] Please refer to Figure 12 As shown, an etching process is performed using the second mask layer 50 as a mask, and a first groove 61 is formed below the first etching window 51, which penetrates the titanium oxide layer 31 and the oxide layer 20 and extends into the substrate 10. A second groove 62 is formed below the second etching window 52, ​​which penetrates the titanium nitride layer 30 and the oxide layer 20 and extends into the substrate 10. A third groove 63 is formed below the third etching window 53, which penetrates the titanium oxide layer 31, the titanium nitride layer 30 and the oxide layer 20 and extends into the substrate 10. The depth of the second groove 62 is greater than the depth of the first groove 61, and the depth of the third groove 63 is less than the depth of the second groove 62 and greater than the depth of the first groove 61.

[0073] In one embodiment, the cross-sectional dimensions of the first trench 61, the second trench 62, and the third trench 63 may be equal, that is, three trenches of equal width and different depths are formed in the substrate 10. In another embodiment, the cross-sectional dimensions of the first trench 61, the second trench 62, and the third trench 63 are unequal, for example, the cross-sectional dimensions of the second trench 62, the third trench 63, and the first trench 61 decrease in sequence, thereby forming three trenches of different depths and widths in the substrate 10.

[0074] After forming the first trench 61, the second trench 62 and the third trench 63, the method further includes: removing the second mask layer 50, removing the titanium nitride layer 30 and the oxide layer 20, filling the first trench 61, the second trench 62 and the third trench 63 with an insulating material to form a first trench isolation structure 71, a second trench isolation structure 72 and a third trench isolation structure 73, and forming Figure 13 The structure shown.

[0075] In the groove 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 layers 30 of different thicknesses are oxidized to form titanium oxide layers 31. In this embodiment, the titanium nitride layer 30 in one region is completely oxidized to form the titanium oxide layer 31, the titanium nitride layer 30 in another region is partially oxidized to form the titanium oxide layer 31, and the titanium nitride layer 30 in the third region is not oxidized; then, the titanium oxide layer 31, the titanium nitride layer 30, the oxide layer 20 thereunder, and the substrate 10 in the three regions are sequentially etched to form grooves of three depths. The present invention completely oxidizes the titanium nitride layer 30 in one area, oxidizes a portion of the titanium nitride layer 30 in another area, and does not oxidize the titanium nitride layer 30 in the third area. 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 it is etched, and the shallower the depth of the formed groove. Therefore, the first groove 61, the second groove 62 and the third groove 63 of different depths can be formed in the same etching step.

[0076] Based on this embodiment, three oxidation windows of different thicknesses can be formed in the first mask layer 40. The titanium nitride layer 30 in three regions is oxidized to three different degrees through the three oxidation windows, and four trenches of different depths are ultimately formed together with the regions where the titanium nitride layer 30 is not oxidized. Of course, five or more trenches of different depths can also be formed.

[0077] [Example 3] The difference between this embodiment and the second embodiment is that after the first oxidation window 41 and the second oxidation window 42 are formed in the first mask layer 40 and oxidized, the first mask layer 40 is not removed, and the etching process is directly performed using the first mask layer 40 as a mask.

[0078] Figures 14 and 15 This is a schematic diagram of the steps of the method for making a groove according to the third embodiment of the present invention. Figure 1 、 Figure 2 、 Figure 8 and Figure 9 、 Figure 14 and Figure 15 The method for manufacturing the groove provided in the third embodiment of the present invention is described in detail.

[0079] Please refer to Figure 2 As shown, an oxide layer 20 and a titanium nitride layer 30 are sequentially formed on the substrate 10 .

[0080] 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 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.

[0081] 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 below the first oxidation window 41 is completely oxidized to form a titanium oxide layer 31, and the partial thickness of the titanium nitride layer 30 below the second oxidation window 42 is oxidized to form a titanium oxide layer 31.

[0082] Please refer to Figure 9 and Figure 14 As shown, an etching process is performed using the first mask layer 40 as a mask, and a first trench 61 is formed below the first oxidation window 41, which penetrates the titanium oxide layer 31 and the oxide layer 20 and extends into the substrate 10. A third trench 63 is formed below the second oxidation window 42, which penetrates the titanium oxide layer 31, the titanium nitride layer 30 and the oxide layer 20 and extends into the substrate 10. The depth of the third trench 63 is greater than the depth of the first trench 61.

[0083] 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, 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, and forming Figure 15 The structure shown.

[0084] In the groove 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 layers 30 of different thicknesses are oxidized to form titanium oxide layers 31. In this 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 partially oxidized to form the titanium oxide layer 31; then, the titanium oxide layer 31, the titanium nitride layer 30, the oxide layer 20 thereunder, and the substrate 10 in the two regions are sequentially etched to form grooves of two depths. The present invention completely oxidizes the titanium nitride layer 30 in one area and oxidizes a portion of the titanium nitride layer 30 in another area. 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 it is etched, and the shallower the depth of the formed groove. Therefore, the first groove 61 and the third groove 63 of different depths can be formed in the same etching step.

[0085] In addition, a first oxidation window 41 and a second oxidation window 42 are formed in the first mask layer 40, and the titanium nitride layer 30 is oxidized. Then, the etching process is directly performed 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 oxidation window 42 is used to compensate for the thickness of the titanium oxide layer 31 at the bottom, which can lower the etching selectivity and thus accurately control the etching depth.

[0086] [Example 4] The difference between this embodiment and the third embodiment is that after the first oxidation window 41 and the second oxidation window 42 are formed in the first mask layer 40 and oxidized, 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.

[0087] Figures 16 to 18 This is a schematic diagram of the structure of each step of the groove manufacturing method provided by the fourth embodiment of the present invention. Figure 1 、 Figure 2 、 Figure 8 and Figure 9 、 Figures 16 to 18 as well as Figure 13 The method for manufacturing the groove provided in the fourth embodiment of the present invention is described in detail.

[0088] Please refer to Figure 2As shown, an oxide layer 20 and a titanium nitride layer 30 are sequentially formed on the substrate 10 .

[0089] Please refer to Figure 8 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.

[0090] 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 below the first oxidation window 41 is completely oxidized to form a titanium oxide layer 31, and the partial thickness of the titanium nitride layer 30 below the second oxidation window 42 is oxidized to form a titanium oxide layer 31.

[0091] Please refer to Figure 16 As shown, 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 .

[0092] Please refer to Figure 9 、 Figure 16 and Figure 17 As shown, a first etching window 51 exposing the titanium oxide layer 31 and corresponding to the first oxidation window 41 and a third etching window 53 exposing the titanium oxide layer 31 and corresponding to the second oxidation window 42 are formed in the second mask layer 50 and the first mask layer 40, and a second etching window 52 exposing the titanium nitride layer 30 is also formed.

[0093] Please refer to Figure 18 As shown, an etching process is performed using the second mask layer 50 and the first mask layer 40 as masks, and a first groove 61 is formed below the first etching window 51, which penetrates the titanium oxide layer 31 and the oxide layer 20 and extends into the substrate 10. A second groove 62 is formed below the second etching window 52, ​​which penetrates the titanium nitride layer 30 and the oxide layer 20 and extends into the substrate 10. A third groove 63 is formed below the third etching window 53, which penetrates the titanium oxide layer 31, the titanium nitride layer 30 and the oxide layer 20 and extends into the substrate 10. The depth of the second groove 62 is greater than the depth of the first groove 61, and the depth of the third groove 63 is greater than the depth of the first groove 61 and less than the depth of the second groove 62.

[0094] After forming the first trench 61, the second trench 62 and the third trench 63, the method further includes: removing the second mask layer 50 and the first mask layer 40, removing the titanium nitride layer 30 and the oxide layer 20, filling the first trench 61, the second trench 62 and the third trench 63 with an insulating material to form a first trench isolation structure 71, a second trench isolation structure 72 and a third trench isolation structure 73, and forming Figure 13 The structure shown.

[0095] In the groove 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 layers 30 of different thicknesses are oxidized to form titanium oxide layers 31. In this embodiment, the titanium nitride layer 30 in one region is completely oxidized to form the titanium oxide layer 31, the titanium nitride layer 30 in another region is partially oxidized to form the titanium oxide layer 31, and the titanium nitride layer 30 in the third region is not oxidized; then, the titanium oxide layer 31, the titanium nitride layer 30, the oxide layer 20 thereunder, and the substrate 10 in the three regions are sequentially etched to form grooves of three depths. The present invention completely oxidizes the titanium nitride layer 30 in one area, oxidizes a portion of the titanium nitride layer 30 in another area, and does not oxidize the titanium nitride layer 30 in the third area. 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 it is etched, and the shallower the depth of the formed groove. Therefore, the first groove 61, the second groove 62 and the third groove 63 of different depths can be formed in the same etching step.

[0096] In addition, in this embodiment, there is no need to remove the first mask layer 40 , and the second mask layer 50 is directly formed on the first mask layer 40 , thereby saving a step of removing the mask layer.

[0097] In summary, in the method for making a groove provided by the present invention, a substrate is first provided, and an oxide 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 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; then, the titanium oxide layer in each region, or / and the titanium nitride layer and the oxide layer thereunder and the substrate are sequentially etched to form grooves of different depths. The present invention performs different degrees of oxidation on the titanium nitride layer in different regions, so that the titanium nitride layer of 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, and the etching rate of the titanium nitride layer and the titanium oxide layer is different. The thicker the titanium oxide layer, the slower it is etched, and the shallower the depth of the formed groove is, thereby being able to form grooves of different depths in the same etching step.

[0098] Furthermore, the cross-sectional dimensions of the first oxidation window and the second oxidation window are different, and / or the cross-sectional dimensions of the first etching window, the second etching window and the third etching window are different, thereby forming grooves of different widths and depths.

[0099] Furthermore, a first oxidation window and a second oxidation window are formed in the first mask layer, and the titanium nitride layer is oxidized. Then, an etching process is performed directly using the first mask layer as a mask. Since the etching selectivity ratio of titanium nitride to titanium oxide is relatively large, the thickness of the titanium oxide layer at the bottom is compensated by the first mask layer retained at the bottom of the second oxidation window, thereby lowering the etching selectivity and accurately controlling the etching depth.

[0100] It should be noted that the embodiments in this specification are described in a progressive manner, and the manufacturing methods described later focus on the differences from the manufacturing methods described previously, and the similarities and similarities between the various embodiments can be referred to each other.

[0101] The above description is only a description of the preferred embodiments of the present invention and does not limit the scope of the present invention. Any changes and modifications made by ordinary technicians 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 method for making a groove, characterized in that: The following steps are involved: providing a substrate, and sequentially forming an oxide layer and a titanium nitride layer on the substrate; Oxidizing different areas of the titanium nitride layer to different degrees, so that the titanium nitride layer of 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; as well as The titanium oxide layer and / or the titanium nitride layer in each region and the oxide layer and the substrate thereunder are etched in sequence to form grooves of different depths.

2. The method for manufacturing a groove according to claim 1, wherein: The method of oxidizing the titanium nitride layer in different regions to different degrees and etching to form grooves of different depths includes: forming a first mask layer on the titanium nitride layer, and forming a first oxidation window exposing the titanium nitride layer in the first mask layer; oxidizing the titanium nitride layer 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; removing the first mask layer and forming a second mask layer on the titanium nitride layer and the titanium oxide layer; 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; performing an etching process using the second mask layer as a mask to form a first trench below the first etching window, which penetrates the titanium oxide layer and the oxide layer and extends into the substrate; and forming a second trench below the second etching window, which penetrates the titanium nitride layer and the oxide layer and extends into the substrate, wherein the depth of the second trench is greater than the depth of the first trench; and The second mask layer is removed.

3. The method for manufacturing a groove according to claim 2, wherein: The first mask layer and the second mask layer are photoresist layers.

4. The method for manufacturing a groove according to claim 2, wherein: While forming a first oxidation 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 is smaller than the depth of the first oxidation window.

5. The method for manufacturing a groove according to claim 4, characterized in that: While oxidizing the titanium nitride layer through the first oxidation window, the titanium nitride layer is 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 exposing the titanium oxide layer is also formed in the second mask layer, wherein the third etching window corresponds to the second etching window; During the etching process using the second mask layer as a mask, a third trench is formed below the third etching window, which penetrates the titanium oxide layer, the titanium nitride layer and the oxide layer and extends to the substrate. The depth of the third trench is less than the depth of the second trench and greater than the depth of the first trench.

6. The method for manufacturing a groove according to claim 1, wherein: The method of oxidizing the titanium nitride layer in different regions to different degrees and etching to form grooves of different depths includes: 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; oxidizing the titanium nitride layer 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 a portion of the titanium nitride layer below the second oxidation window is oxidized to form a titanium nitride layer; performing an etching process using the first mask layer as a mask to form a first trench below the first oxidation window, the trench penetrating the titanium oxide layer and the oxide layer and extending into the substrate; and forming a third trench below the second oxidation window, the trench penetrating the titanium oxide layer, the titanium nitride layer, and the oxide layer and extending into the substrate, wherein the depth of the third trench is greater than the depth of the first trench; and The first mask layer is removed.

7. The method for manufacturing a groove according to claim 1, wherein: The method of oxidizing the titanium nitride layer in different regions to different degrees and etching to form grooves of different depths includes: 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; oxidizing the titanium nitride layer 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 a portion of the titanium nitride layer below the second oxidation window is oxidized to form a titanium nitride layer; forming a second mask layer on the first mask layer, wherein the second mask layer covers the first mask layer and fills the first oxidation window and the second oxidation window; 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 in the second mask layer and forming a second etching window exposing the titanium nitride layer; An etching process is performed using the second mask layer and the first mask layer as masks, forming a first trench below the first etching window that penetrates the titanium oxide layer and the oxide layer and extends into the substrate, forming a second trench below the second etching window that penetrates the titanium nitride layer and the oxide layer and extends into the substrate, and forming a third trench below the third etching window that penetrates the titanium oxide layer, the titanium nitride layer, and the oxide layer and extends 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; and The second mask layer and the first mask layer are removed.

8. The method for manufacturing a groove 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 of forming a first oxidation window and a second oxidation window in the first mask layer includes: forming a photoresist layer on the first mask layer; exposing the photoresist layer using a half-tone mask or a step mask and developing the photoresist layer to form a patterned photoresist layer; Using the patterned photoresist layer as a mask, etching the first mask layer to form a first oxidation window and a second oxidation window of different depths in the first mask layer; and The patterned photoresist layer is removed.

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

10. The method for manufacturing a groove according to claim 1, wherein: After forming the trench, the method further includes removing the titanium nitride layer and the oxide layer.

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