Method of forming capacitor

Abstract

The present disclosure provides a method of forming a capacitor. The method includes the following operations. A metal oxide insulating layer is formed on the first conductive layer at a first temperature, wherein the first temperature is lower than a crystallization temperature of the metal oxide insulating layer. A second conductive layer is formed on the metal oxide insulating layer at a second temperature. Forming an insulating layer on the second conductive layer at a third temperature, and crystallizing the metal oxide insulating layer to form a crystallized metal oxide insulating layer, the second temperature being between the first temperature and the third temperature; the first temperature, the second temperature and the third temperature are used in a gradient increasing mode when the capacitor is formed, the method of the present disclosure can be easily implemented, the capacitor with a high length-width ratio can be formed through the method of the present disclosure, the capacitance of the capacitor is improved, and leakage current is avoided.

Description

Technical Field

[0001] The present disclosure relates to a method of forming a capacitor. Background Art

[0002] A memory cell comprising a capacitor and a transistor is the basic unit for storing data in a memory device. Data is stored in the form of electric charge in the capacitor. The transistor controls the charging and discharging of the capacitor. However, as the size of memory devices is getting smaller and smaller, it becomes challenging to achieve high capacitance in a small capacitor. In addition, avoiding leakage current is crucial for a memory device to have good performance while having a capacitor that can maintain high capacitance. Therefore, a method of forming a capacitor with high capacitance and reduced leakage current is very important. Summary of the invention

[0003] The present disclosure provides a method for forming a capacitor. The method includes the following operations. A metal oxide insulating layer is formed on a first conductive layer at a first temperature, wherein the first temperature is lower than a crystallization temperature of the metal oxide insulating layer. A second conductive layer is formed on the metal oxide insulating layer at a second temperature. An insulating layer is formed on the second conductive layer at a third temperature to crystallize the metal oxide insulating layer to form a crystallized metal oxide insulating layer, wherein the second temperature is between the first temperature and the third temperature.

[0004] In some embodiments, the second temperature is lower than a crystallization temperature of the metal oxide insulating layer.

[0005] In some embodiments, the metal oxide insulating layer includes hafnium zirconium oxide, zirconium oxide, hafnium oxide, titanium oxide, or a combination thereof.

[0006] In some embodiments, the first temperature is in the range of 180°C to 280°C.

[0007] In some embodiments, the second temperature is greater than the first temperature and equal to or less than 330°C.

[0008] In some embodiments, the third temperature is equal to or greater than 330°C and less than 450°C.

[0009] In some embodiments, the method further includes forming a first conductive layer on the cylindrical substrate.

[0010] In some embodiments, the crystallized metal oxide insulating layer includes a plurality of crystals uniformly arranged in a plurality of lines.

[0011] In some embodiments, the method further includes forming a first conductive layer on the cylindrical substrate, and etching the cylindrical substrate to form the first conductive layer to have a hollow cylindrical shape.

[0012] In some embodiments, forming a metal oxide insulating layer includes forming an outer metal oxide insulating layer and an inner metal oxide insulating layer on the outer surface and inner surface of a first conductive layer having a hollow cylindrical shape, respectively; forming a second conductive layer includes forming an outer second conductive layer on the outer metal oxide insulating layer and forming an inner second conductive layer on the inner metal oxide insulating layer; and forming an insulating layer includes forming an outer insulating layer on the outer second conductive layer and forming an inner insulating layer on the inner second conductive layer.

[0013] In some embodiments, the crystallized metal oxide insulating layer includes a plurality of crystals uniformly arranged in a plurality of lines.

[0014] In some embodiments, the first conductive layer includes titanium, aluminum, titanium nitride, or a combination thereof, and the second conductive layer includes titanium, aluminum, titanium nitride, or a combination thereof.

[0015] The present disclosure also provides a method for forming a capacitor. The method includes the following operations. A metal oxide insulating layer is formed on a first conductive layer at a first temperature equal to or greater than 180°C. A second conductive layer is formed on the metal oxide insulating layer at a second temperature in the range of 280°C to 330°C. An insulating layer is formed on the second conductive layer at a third temperature lower than 450°C, wherein the third temperature is greater than the second temperature, and the second temperature is greater than the first temperature.

[0016] In some embodiments, before forming the insulating layer, the metal oxide insulating layer is amorphous, and after forming the insulating layer, the metal oxide insulating layer is crystalline.

[0017] In some embodiments, the metal oxide insulating layer includes hafnium zirconium oxide, zirconium oxide, hafnium oxide, titanium oxide, or a combination thereof.

[0018] In some embodiments, the method further includes forming a first conductive layer on the cylindrical substrate.

[0019] In some embodiments, the crystallized metal oxide insulating layer includes a plurality of crystals uniformly arranged in a plurality of lines.

[0020] In some embodiments, the method further includes forming a first conductive layer on the cylindrical substrate, and etching the cylindrical substrate to form the first conductive layer to have a hollow cylindrical shape.

[0021] In some embodiments, forming a metal oxide insulating layer includes forming an outer metal oxide insulating layer and an inner metal oxide insulating layer on the outer surface and inner surface of a first conductive layer having a hollow cylindrical shape, respectively; forming a second conductive layer includes forming an outer second conductive layer on the outer metal oxide insulating layer and forming an inner second conductive layer on the inner metal oxide insulating layer; and forming an insulating layer includes forming an outer insulating layer on the outer second conductive layer and forming an inner insulating layer on the inner second conductive layer.

[0022] In some embodiments, the crystallized metal oxide insulating layer includes a plurality of crystals uniformly arranged in a plurality of lines.

[0023] The features, aspects and advantages of the present disclosure may be better understood by referring to the following detailed description. It should be noted that the above general description and the following detailed description are exemplary and are intended to provide further explanation of the appended claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The present disclosure can be best understood from the following detailed description and accompanying drawings. It should be noted that the elements in the drawings may not meet the exact proportions. The size of some elements may be increased or reduced for clarity of discussion.

[0025] Figure 1 is a flow chart of a method of forming a capacitor according to some embodiments of the present disclosure.

[0026] Figure 2A , Figure 3A , Figure 4A and Figure 5A FIG. 4 is a schematic top view of a capacitor at an intermediate stage in the method for forming a capacitor according to the first embodiment or the third embodiment of the present disclosure.

[0027] Figure 2B , Figure 3B , Figure 4B and Figure 5B is a schematic cross-sectional view of a capacitor at an intermediate stage in the method for forming a capacitor according to the first embodiment or the third embodiment of the present disclosure.

[0028] Fig. 6A , Fig. 7A , Fig. 8A , Fig.9A and Fig. 10A is a schematic top view of a capacitor at an intermediate stage in the method for forming a capacitor according to the second embodiment or the fourth embodiment of the present disclosure.

[0029] Figure 6B , Figure 7B , Figure 8B , Fig. 9B and Fig. 10B is a schematic cross-sectional view of a capacitor at an intermediate stage in the method for forming a capacitor according to the second embodiment or the fourth embodiment of the present disclosure.

[0030] Fig.11 is a flow chart of a method of forming a capacitor according to some embodiments of the present disclosure.

[0031] Fig.12 According to the second embodiment or the fourth embodiment of the present disclosure, Fig. 10A Electron microscope image of a portion of a capacitor. DETAILED DESCRIPTION

[0032] In order to make the description of the present disclosure more detailed and complete, the following provides an illustrative description of the aspects of the embodiments and specific embodiments. This is not to limit the embodiments of the present disclosure to the only form. The embodiments of the present disclosure may be combined or replaced with each other in a beneficial situation. Other embodiments may also be attached without further description or explanation.

[0033] In addition, spatially relative terms, such as above and below, etc., may be used in the present disclosure to describe the relationship of one element or feature to another element or feature in the figure. In addition to the directions described in the figures, spatially relative terms are intended to include different directions of the device when in use or operation. For example, the device can be oriented in other ways (e.g., rotated 90 degrees or otherwise), and the spatially relative terms of the present disclosure can be interpreted accordingly. In the present disclosure, unless otherwise stated, the same element number in different figures refers to the same or similar elements formed by the same or similar materials by the same or similar methods.

[0034] The present disclosure provides a method for forming a capacitor. The method includes the following operations. A metal oxide insulating layer is formed on a first conductive layer at a first temperature, wherein the first temperature is lower than a crystallization temperature of the metal oxide insulating layer. A second conductive layer is formed on the metal oxide insulating layer at a second temperature. An insulating layer is formed on the second conductive layer at a third temperature to crystallize the metal oxide insulating layer to form a crystallized metal oxide insulating layer, wherein the second temperature is between the first temperature and the third temperature. Details of the method are provided below according to some embodiments.

[0035] Figure 1 is a flow chart of the above method 100 according to some embodiments of the present disclosure. Figure 2A , Figure 3A , Figure 4A and Figure 5A Top view and Figure 2B , Figure 3B , Figure 4B and Figure 5B The cross-sectional view is a schematic diagram of a capacitor at an intermediate stage in the method 100 according to the first embodiment of the present disclosure. Figure 1 Please also read FIG. 2A to FIG. 5B . Fig. 6A , Fig. 7A , Fig. 8A , Fig.9A and Fig. 10A Top view and Figure 6B , Figure 7B , Figure 8B , Fig. 9B and Fig. 10B The cross-sectional view is a schematic diagram of a capacitor at an intermediate stage in the method 100 according to the second embodiment of the present disclosure. The differences between the first embodiment and the second embodiment are explained as follows. Figure 1 Please also read FIG. 6A to FIG. 10B .

[0036] exist Figure 1 In the embodiment, operation 101 includes forming a metal oxide insulating layer 203 on a first conductive layer 202 at a first temperature, wherein the first temperature is lower than a crystallization temperature of the metal oxide insulating layer 203. Figure 2A and Figures 2B to 3A and Figure 3B ,as well as Fig. 6A and FIG. 6B to FIG. 8A and Figure 8B . In some embodiments, before performing operation 101, the first conductive layer 202 can be formed on any substrate, such as the cylindrical substrate 201 discussed below, and the substrate can be of any shape, such as a flat plate or a cylindrical shape. With the help of the first temperature, the material of the metal oxide insulating layer 203 is deposited on the first conductive layer 202 and reacts to form the metal oxide insulating layer 203. When the first temperature is lower than the crystallization temperature of the metal oxide insulating layer 203, the metal oxide insulating layer 203 formed on the first conductive layer 202 is amorphous. Avoiding crystallization of the metal oxide insulating layer 203 before performing subsequent operations can avoid the problem of excessive crystallinity causing leakage current in the capacitor. In some embodiments, the first temperature is in the range of 180°C to 280°C, such as 180°C, 200°C, 220°C, 240°C, 260°C or 280°C. In some embodiments, the first conductive layer 202 includes titanium, aluminum, titanium nitride or a combination thereof. In some embodiments, the metal oxide insulating layer 203 includes hafnium zirconium oxide, zirconium oxide, hafnium oxide, titanium oxide, or a combination thereof. In some embodiments, forming the metal oxide insulating layer 203 includes performing an atomic layer deposition (ALD) process.

[0037] In some embodiments, the method 100 further includes forming a first conductive layer 202 on the cylindrical substrate 201, for example Figure 2A and Figures 2B to 3A and Figure 3B The first embodiment shown. When the first conductive layer 202 is formed on the cylindrical substrate 201, the first conductive layer 202 is in the shape of a hollow cylinder, and the metal oxide insulating layer 203 formed on the first conductive layer 202 is also in the shape of a hollow cylinder. In operation 103 discussed below, the hollow cylindrical shape is conducive to the crystallization of the metal oxide insulating layer 203. In some embodiments, the cylindrical substrate 201 includes silicon or silicon dioxide.

[0038] In some embodiments, the method 100 further includes forming a first conductive layer 202 on the cylindrical substrate 201, and then etching the cylindrical substrate 201 to form a hollow cylindrical first conductive layer 202, such as Fig. 6A and FIG. 6B to FIG. 8A and Figure 8BThe second embodiment shown. Since the first conductive layer 202 is formed on the cylindrical substrate 201, the shape of the first conductive layer 202 is a hollow cylinder. After etching the cylindrical substrate 201 wrapped in the first conductive layer 202, the inner surface 202I and the outer surface 202O of the first conductive layer 202 are exposed. Therefore, the formation of the metal oxide insulating layer 203 in operation 101 includes forming an outer metal oxide insulating layer 203A on the outer surface 202O of the first conductive layer 202 and forming an inner metal oxide insulating layer 203B on the inner surface 202I of the first conductive layer 202. The metal oxide insulating layer 203 in the second embodiment includes an outer metal oxide insulating layer 203A and an inner metal oxide insulating layer 203B, and the outer metal oxide insulating layer 203A and the inner metal oxide insulating layer 203B are both hollow cylindrical. In operation 103 discussed below, the hollow cylindrical shape is conducive to the crystallization of the metal oxide insulating layer 203. In addition, since the capacitor of the second embodiment includes two separated dielectric parts for storing charge, namely, the outer metal oxide insulating layer 203A and the inner metal oxide insulating layer 203B, the capacitance of the capacitor of the second embodiment is greater than the capacitance of the capacitor of the first embodiment. In some embodiments, the cylindrical substrate 201 includes silicon or silicon dioxide. In some embodiments, the outer metal oxide insulating layer 203A includes hafnium zirconium oxide, zirconium oxide, hafnium oxide, titanium oxide, or a combination thereof, and the inner metal oxide insulating layer 203B includes hafnium zirconium oxide, zirconium oxide, hafnium oxide, titanium oxide, or a combination thereof. In some embodiments, etching the cylindrical substrate 201 includes any feasible semiconductor process. In some embodiments, forming the outer metal oxide insulating layer 203A includes performing an atomic layer deposition (ALD) process, and forming the inner metal oxide insulating layer 203B includes performing an atomic layer deposition (ALD) process.

[0039] exist Figure 1 In the embodiment, operation 102 includes forming a second conductive layer 204 on the metal oxide insulating layer 203 at a second temperature. Figure 3A and FIG. 3B to FIG. 4A and Figure 4B ,as well as Fig. 8A and FIG. 8B to FIG. 9A and Figure 8B. With the help of the second temperature, the material of the second conductive layer 204 is deposited on the metal oxide insulating layer 203 and reacts to form the second conductive layer 204. In some embodiments, the second temperature is lower than the crystallization temperature of the metal oxide insulating layer 203. When the second temperature is lower than the crystallization temperature of the metal oxide insulating layer 203, the metal oxide insulating layer 203 is still amorphous in operation 102. Therefore, the crystallization of the metal oxide insulating layer 203 is suppressed until operation 103 is performed to avoid excessive crystallinity in the metal oxide insulating layer 203 causing leakage current of the capacitor. In some embodiments, the second temperature is greater than the first temperature, and the second temperature is equal to or lower than 330° C., for example, equal to or lower than 320° C., equal to or lower than 310° C., equal to or lower than 300° C., equal to or lower than 290° C., or equal to or lower than 280° C. When the second temperature is greater than the first temperature, the crystallization of the metal oxide insulating layer 203 can be prepared (or facilitated) in operation 103 as the temperature gradient increases. The crystallization of the metal oxide insulating layer 203 increases the capacitance of the metal oxide insulating layer 203. In some embodiments, the second conductive layer 204 includes titanium, aluminum, titanium nitride, or a combination thereof. In some embodiments, forming the second conductive layer 204 includes performing an atomic layer deposition (ALD) process.

[0040] exist Figure 3A and FIG. 3B to FIG. 4A and Figure 4B In the first embodiment shown, the second conductive layer 204 formed on the hollow cylindrical metal oxide insulating layer 203 is also hollow cylindrical. Since the hollow cylindrical metal oxide insulating layer 203 is sandwiched between the hollow cylindrical first conductive layer 202 and the hollow cylindrical second conductive layer 204, this shape provides guidance for the growth direction of crystals in the metal oxide insulating layer 203 in operation 103. In other words, the crystallinity of the metal oxide insulating layer 203 can be increased in operation 103 to increase the capacitance of the capacitor.

[0041] exist Fig. 8A and FIG. 8B to FIG. 9A and Fig. 9BIn the second embodiment shown, the operation 102 of forming the second conductive layer 204 includes forming the outer second conductive layer 204A on the outer metal oxide insulating layer 203A, and forming the inner second conductive layer 204B on the inner metal oxide insulating layer 203B. In other words, the second conductive layer 204 in the second embodiment includes the outer second conductive layer 204A and the inner second conductive layer 204B, wherein the outer second conductive layer 204A formed on the hollow cylindrical outer metal oxide insulating layer 203A is also hollow cylindrical, and the inner second conductive layer 204B formed on the hollow cylindrical inner metal oxide insulating layer 203B is also hollow cylindrical. Since the hollow cylindrical first conductive layer 202 and the hollow cylindrical outer second conductive layer 204A and the hollow cylindrical inner second conductive layer 204B respectively sandwich the outer metal oxide insulating layer 203A and the inner metal oxide insulating layer 203B, such a shape provides a guide for the growth direction of crystals in the outer metal oxide insulating layer 203A and the inner metal oxide insulating layer 203B in operation 103. In other words, the crystallinity of the outer metal oxide insulating layer 203A and the inner metal oxide insulating layer 203B can be increased in operation 103 to increase the capacitance of the capacitor. In some embodiments, the outer second conductive layer 204A includes titanium, aluminum, titanium nitride, or a combination thereof, and the inner second conductive layer 204B includes titanium, aluminum, titanium nitride, or a combination thereof. In some embodiments, forming the outer second conductive layer 204A includes performing an atomic layer deposition (ALD) process, and forming the inner second conductive layer 204B includes performing an atomic layer deposition (ALD) process.

[0042] exist Figure 1 In the embodiment, operation 103 includes forming an insulating layer 205 on the second conductive layer 204 at a third temperature, and allowing the metal oxide insulating layer 203 to be crystallized to form a crystallized metal oxide insulating layer 203', wherein the second temperature is between the first temperature and the third temperature (or the third temperature is greater than the second temperature, and the second temperature is greater than the first temperature). Figure 4A and FIG. 4B to FIG. 5A and Figure 5B ,as well as Fig.9A and FIG. 9B to FIG. 10A and Fig. 10B. Since the third temperature can crystallize the metal oxide insulating layer 203, the capacitance of the capacitor increases. In some embodiments, the third temperature is equal to or greater than 330°C and lower than 450°C, for example, 330°C, 350°C, 370°C, 390°C, 410°C or 430°C. When the third temperature is lower than 450°C, excessive crystallinity in the crystallized metal oxide insulating layer 203' can be avoided, thereby avoiding the problem of leakage current in the capacitor. In some embodiments, the insulating layer 205 includes but is not limited to polycrystalline germanium. In some embodiments, forming the insulating layer 205 includes performing an atomic layer deposition (ALD) process.

[0043] exist Figure 4A and FIG. 4B to FIG. 5A and Figure 5B In the first embodiment shown, the insulating layer 205 formed on the hollow cylindrical second conductive layer 204 is also in the shape of a hollow cylinder. The hollow cylindrical insulating layer 205 encapsulating the second conductive layer 204, the metal oxide insulating layer 203 and the first conductive layer 202 provides structural support for a capacitor having a high aspect ratio. In addition, in the case where a plurality of capacitors can be formed, the insulating layer 205 can provide insulation between adjacent capacitors to avoid electrical short circuits. In addition, the crystallized metal oxide insulating layer 203' formed in operation 103 includes the above-mentioned crystal growth into a uniformly arranged line due to being sandwiched between the hollow cylinders, thereby increasing the capacitance of the capacitor.

[0044] exist Fig.9A and FIG. 9B to FIG. 10A and Fig. 10BIn the second embodiment shown, the operation 103 of forming the insulating layer 205 includes forming an outer insulating layer 205A on the outer second conductive layer 204A, and forming an inner insulating layer 205B on the inner second conductive layer 204B. In other words, the insulating layer 205 in the second embodiment includes an outer insulating layer 205A and an inner insulating layer 205B, wherein the outer insulating layer 205A formed on the hollow cylindrical outer second conductive layer 204A is also hollow cylindrical, and the inner insulating layer 205B formed on the hollow cylindrical inner second conductive layer 204B is also hollow cylindrical. The outer insulating layer 205A in the hollow cylindrical shape that wraps multiple layers can provide structural support for capacitors with a high aspect ratio. In addition, in the case where there can be multiple capacitors, the outer insulating layer 205A provides insulation between adjacent capacitors to avoid electrical short circuits. In addition, the crystallized metal oxide insulating layer 203', i.e., the crystallized outer metal oxide insulating layer 203A' and the crystallized inner metal oxide insulating layer 203B', have crystals uniformly arranged in a linear shape by being sandwiched between the hollow cylinders in operation 103, thereby increasing the capacitance of the capacitor. In some embodiments, the outer insulating layer 205A includes, but is not limited to, polycrystalline germanium, and the inner insulating layer 205B includes, but is not limited to, polycrystalline germanium. In some embodiments, forming the outer insulating layer 205A includes performing an atomic layer deposition (ALD) process, and forming the inner insulating layer 205B includes performing an atomic layer deposition (ALD) process.

[0045] The present disclosure also provides a method for forming a capacitor. The method includes the following operations. A metal oxide insulating layer is formed on a first conductive layer at a first temperature equal to or greater than 180°C. A second conductive layer is formed on the metal oxide insulating layer at a second temperature in the range of 280°C to 330°C. An insulating layer is formed on the second conductive layer at a third temperature lower than 450°C, wherein the third temperature is greater than the second temperature, and the second temperature is greater than the first temperature. Details of the method are provided below according to some embodiments.

[0046] Fig.11 is a flow chart of the above method 300 according to some embodiments of the present disclosure. It should be noted that, FIG. 2A to FIG. 10B The capacitor shown may also be used to explain the method 300. Therefore, in order to simplify the present disclosure, the capacitor is repeatedly used in the following text. FIG. 2A to FIG. 10B ,in Figure 2A , Figure 3A , Figure 4A and Figure 5A Top view and Figure 2B , Figure 3B , Figure 4B and Figure 5Bis a cross-sectional view of a capacitor at an intermediate stage in method 300 according to a third embodiment of the present disclosure, and Fig. 6A , Fig. 7A , Fig. 8A , Fig.9A and Fig. 10A Top view and Figure 6B , Figure 7B , Figure 8B , Fig. 9B and Fig. 10B The cross-sectional view is a schematic diagram of a capacitor at an intermediate stage in the method 300 according to the fourth embodiment of the present disclosure. Fig.11 Please also read FIG. 2A to FIG. 10B .

[0047] exist Fig.11 In the embodiment, operation 301 includes forming a metal oxide insulating layer 203 on the first conductive layer 202 at a first temperature equal to or greater than 180° C. (e.g., equal to or greater than 200° C., equal to or greater than 220° C., equal to or greater than 240° C., equal to or greater than 260° C., or equal to or greater than 280° C.). Figure 2A and Figures 2B to 3A and Figure 3B ,as well as Fig. 6A and FIG. 6B to FIG. 8A and Figure 8B . In some embodiments, before operation 301, the first conductive layer 202 can be formed on any substrate, such as a cylindrical substrate 201 discussed below, and the substrate can be of any shape, such as a flat plate or a cylindrical shape. With the help of the first temperature, the material of the metal oxide insulating layer 203 is deposited on the first conductive layer 202 and reacts to form the metal oxide insulating layer 203. In addition, since the first temperature is lower than the second temperature in operation 302 discussed below, the metal oxide insulating layer 203 formed on the first conductive layer 202 in operation 301 is amorphous. In other words, before performing the operations discussed below, operation 301 avoids crystallization of the metal oxide insulating layer 203 to avoid excessive crystallinity causing leakage current of the capacitor. In some embodiments, the first conductive layer 202 includes titanium, aluminum, titanium nitride, or a combination thereof. In some embodiments, the metal oxide insulating layer 203 includes hafnium zirconium oxide, zirconium oxide, hafnium oxide, titanium oxide, or a combination thereof. In some embodiments, forming the metal oxide insulating layer 203 includes performing an atomic layer deposition (ALD) process.

[0048] In some embodiments, the method 300 further includes forming a first conductive layer 202 on the cylindrical substrate 201, for example Figure 2A and Figures 2B to 3A and Figure 3BThe third embodiment shown in FIG. The formation of the first conductive layer 202 on the cylindrical substrate 201 in the third embodiment is substantially the same as the formation of the first conductive layer 202 on the cylindrical substrate 201 in the first embodiment. Therefore, please refer to the detailed description above.

[0049] In some embodiments, the method 300 further includes forming a first conductive layer 202 on the cylindrical substrate 201, and etching the cylindrical substrate 201 to form a hollow cylindrical first conductive layer 202, for example Fig. 6A and FIG. 6B to FIG. 8A and Figure 8B The fourth embodiment shown. The process of forming the first conductive layer 202 on the cylindrical substrate 201 and etching the cylindrical substrate 201 to form the hollow cylindrical first conductive layer 202 in the fourth embodiment is substantially the same as the process of forming the first conductive layer 202 on the cylindrical substrate 201 and etching the cylindrical substrate 201 to form the hollow cylindrical first conductive layer 202 in the second embodiment. Therefore, please refer to the detailed description above.

[0050] exist Fig.11 In the embodiment, operation 302 includes forming a second conductive layer 204 on the metal oxide insulating layer 203 at a second temperature in the range of 280° C. to 330° C. Figure 3A and FIG. 3B to FIG. 4A and Figure 4B ,as well as Fig. 8A and FIG. 8B to FIG. 9A and Figure 8B . With the help of the second temperature, the material of the second conductive layer 204 is deposited on the metal oxide insulating layer 203 and reacts to form the second conductive layer 204. In addition, since the second temperature is in the range of 280° C. to 330° C., for example, 280° C., 290° C., 300° C., 310° C., 320° C., or 330° C., the metal oxide insulating layer 203 in operation 302 is amorphous. In other words, before operation 303 discussed below is performed, the metal oxide insulating layer 203 can be prevented from being crystallized to avoid excessive crystallinity in the metal oxide insulating layer 203 and causing leakage current of the capacitor. In addition, since the second temperature is greater than the first temperature, the increase in the temperature gradient can prepare for (or facilitate) the crystallization of the metal oxide insulating layer 203 before performing operation 303. The crystallization of the metal oxide insulating layer 203 can increase the capacitance of the metal oxide insulating layer 203. In some embodiments, the second conductive layer 204 includes titanium, aluminum, titanium nitride, or a combination thereof. In some embodiments, forming the second conductive layer 204 includes performing an atomic layer deposition (ALD) process.

[0051] exist Figure 3A and FIG. 3B to FIG. 4A and Figure 4BIn the third embodiment shown, the second conductive layer 204 formed on the hollow cylindrical metal oxide insulating layer 203 is also hollow cylindrical. Since the hollow cylindrical first conductive layer 202 and the hollow cylindrical second conductive layer 204 sandwich the metal oxide insulating layer 203, this shape provides guidance for the growth direction of crystals in the metal oxide insulating layer 203 in operation 303. In other words, the crystallinity of the metal oxide insulating layer 203 is increased in operation 303 to increase the capacitance of the capacitor.

[0052] exist Fig. 8A and FIG. 8B to FIG. 9A and Fig. 9B In the fourth embodiment shown, the operation 302 of forming the second conductive layer 204 includes forming the outer second conductive layer 204A on the outer metal oxide insulating layer 203A, and forming the inner second conductive layer 204B on the inner metal oxide insulating layer 203B. In other words, the second conductive layer 204 in the fourth embodiment includes the outer second conductive layer 204A and the inner second conductive layer 204B, wherein the outer second conductive layer 204A formed on the outer metal oxide insulating layer 203A in the shape of a hollow cylinder is also in the shape of a hollow cylinder, and the inner second conductive layer 204B formed on the inner metal oxide insulating layer 203B in the shape of a hollow cylinder is also in the shape of a hollow cylinder. Since the hollow cylindrical first conductive layer 202 and the hollow cylindrical outer second conductive layer 204A and the hollow cylindrical inner second conductive layer 204B sandwich the outer metal oxide insulating layer 203A and the inner metal oxide insulating layer 203B respectively, this shape provides guidance for the direction of crystal growth in the outer metal oxide insulating layer 203A and the inner metal oxide insulating layer 203B in operation 303. In other words, the crystallinity of the outer metal oxide insulating layer 203A and the inner metal oxide insulating layer 203B can be increased in operation 303 to increase the capacitance of the capacitor. In some embodiments, the outer second conductive layer 204A includes titanium, aluminum, titanium nitride, or a combination thereof, and the inner second conductive layer 204B includes titanium, aluminum, titanium nitride, or a combination thereof. In some embodiments, forming the outer second conductive layer 204A includes performing an atomic layer deposition (ALD) process, and forming the inner second conductive layer 204B includes performing an atomic layer deposition (ALD) process.

[0053] exist Fig.11 In the embodiment, operation 303 includes forming an insulating layer 205 on the second conductive layer 204 at a third temperature lower than 450°C (e.g., lower than 430°C, lower than 410°C, lower than 390°C, lower than 370°C, or lower than 350°C), wherein the third temperature is greater than the second temperature, and the second temperature is greater than the first temperature. Figure 4A and FIG. 4B to FIG. 5Aand Figure 5B ,as well as Fig.9A and FIG. 9B to FIG. 10A and Fig. 10B . Since the third temperature is greater than the second temperature, the metal oxide insulating layer 203 is crystallized into a crystallized metal oxide insulating layer 203', thereby increasing the capacitance of the capacitor. In other words, before forming the insulating layer 205, the metal oxide insulating layer 203 is amorphous, and after forming the insulating layer 205, the metal oxide insulating layer 203 is crystallized. In addition, when the third temperature is lower than 450°C, excessive crystallinity in the crystallized metal oxide insulating layer 203' can be avoided to prevent leakage current problems occurring in the capacitor. In some embodiments, the insulating layer 205 includes, but is not limited to, polycrystalline germanium. In some embodiments, forming the insulating layer 205 includes performing an atomic layer deposition (ALD) process.

[0054] exist Figure 4A and FIG. 4B to FIG. 5A and Figure 5B In the third embodiment shown, the insulating layer 205 formed on the hollow cylindrical second conductive layer 204 is also hollow cylindrical. The hollow cylindrical insulating layer 205 encapsulating the second conductive layer 204, the metal oxide insulating layer 203 and the first conductive layer 202 provides structural support for the capacitor with a high aspect ratio. In addition, in the case where multiple capacitors can be formed, the insulating layer 205 provides insulation between adjacent capacitors to avoid electrical short circuits. In addition, the crystallized metal oxide insulating layer 203' formed in operation 303 includes the above-mentioned crystals uniformly arranged in a linear shape due to being sandwiched between the hollow cylinders, so the capacitance of the capacitor is increased.

[0055] exist Fig.9A and FIG. 9B to FIG. 10A and Fig. 10BIn the fourth embodiment shown, the operation 303 of forming the insulating layer 205 includes forming an outer insulating layer 205A on the outer second conductive layer 204A, and forming an inner insulating layer 205B on the inner second conductive layer 204B. In other words, the insulating layer 205 in the fourth embodiment includes an outer insulating layer 205A and an inner insulating layer 205B, wherein the outer insulating layer 205A formed on the hollow cylindrical outer second conductive layer 204A is also hollow cylindrical, and the inner insulating layer 205B formed on the hollow cylindrical inner second conductive layer 204B is also hollow cylindrical. The outer insulating layer 205A in the hollow cylindrical shape that wraps multiple layers provides structural support for capacitors with high aspect ratios. In addition, in the case of forming multiple capacitors, the outer insulating layer 205A provides insulation between adjacent capacitors to avoid electrical short circuits. In addition, the crystallized metal oxide insulating layer 203', i.e., the crystallized outer metal oxide insulating layer 203A' and the crystallized inner metal oxide insulating layer 203B', in operation 303, includes the above-mentioned crystals uniformly arranged in a linear shape due to being sandwiched between the hollow cylinders, so the capacitance of the capacitor is increased. In some embodiments, the outer insulating layer 205A includes but is not limited to polycrystalline germanium, and the inner insulating layer 205B includes but is not limited to polycrystalline germanium. In some embodiments, forming the outer insulating layer 205A includes performing an atomic layer deposition (ALD) process, and forming the inner insulating layer 205B includes performing an atomic layer deposition (ALD) process.

[0056] To further explain the present disclosure in detail, Fig.12 In the electron microscope image of FIG. 1 , the uniformly arranged crystals in the crystallized metal oxide insulating layer 203 ′ in the second embodiment or the fourth embodiment are as shown in FIG. Fig.12 shown. Fig.12 It is from Fig. 10A Electron microscope image captured in the area indicated by the dashed square in . Fig.12 The crystallized metal oxide insulating layer 203' shown includes a crystallized outer metal oxide insulating layer 203A' and a crystallized inner metal oxide insulating layer 203B', and multiple lines can be seen under an electron microscope to indicate the growth direction of the crystals. The significant crystal arrangement indicates that the capacitor has sufficient crystallinity to increase the capacitance of the capacitor. The electron microscope images (not shown) of the first embodiment and the third embodiment also have crystals uniformly arranged in lines in the crystallized metal oxide insulating layer 203'.

[0057] The present disclosure provides a method for forming a capacitor with high capacitance and low leakage current. The method of the present disclosure can be easily implemented by using a first temperature, a second temperature, and a third temperature in a gradient increasing manner when forming the capacitor. By the method provided by the present disclosure, a capacitor with a high aspect ratio can not only be formed to have an increased capacitance, but also to avoid undesirable leakage current.

[0058] The present disclosure describes the present disclosure in considerable detail through embodiments. However, other embodiments may also be feasible. Therefore, the scope and spirit of the appended claims should not be limited to the description of the embodiments in the present disclosure.

[0059] It will be apparent to those skilled in the art that modifications and changes may be made to the present disclosure without departing from the spirit and scope of the present disclosure, and the present disclosure shall include such modifications and changes if they fall within the scope and spirit of the appended claims.

[0060]

Explanation of symbols

[0061] 100: Method

[0062] 101: Operation

[0063] 102: Operation

[0064] 103: Operation

[0065] 201: Cylindrical substrate

[0066] 202: first conductive layer

[0067] 203:Metal oxide insulating layer

[0068] 204: second conductive layer

[0069] 205: Insulation layer

[0070] 300: Methods

[0071] 301: Operation

[0072] 302: Operation

[0073] 303: Operation

[0074] 202I: Inner surface

[0075] 202O: Outer surface

[0076] 203': Crystalline metal oxide insulating layer

[0077] 203A: External metal oxide insulation layer

[0078] 203A': Crystalline outer metal oxide insulating layer

[0079] 203B: Internal metal oxide insulation layer

[0080] 203B': Metal oxide insulating layer inside the crystal

[0081] 204A: External second conductive layer

[0082] 204B: The second inner conductive layer

[0083] 205A: External insulation layer

[0084] 205B: Inner insulation layer.

Claims

1. A method for forming a capacitor, characterized in that: include: forming a metal oxide insulating layer on the first conductive layer at a first temperature, wherein the first temperature is lower than a crystallization temperature of the metal oxide insulating layer; forming a second conductive layer on the metal oxide insulating layer at a second temperature; as well as An insulating layer is formed on the second conductive layer at a third temperature to crystallize the metal oxide insulating layer to form a crystallized metal oxide insulating layer, wherein the second temperature is between the first temperature and the third temperature. 2 . The method according to claim 1 , wherein the second temperature is lower than the crystallization temperature of the metal oxide insulating layer. 3 . The method according to claim 1 , wherein the metal oxide insulating layer comprises hafnium zirconium oxide, zirconium oxide, hafnium oxide, titanium oxide or a combination thereof. The method according to claim 1 , wherein the first temperature is in the range of 180° C. to 280° C. The method according to claim 1 , wherein the second temperature is greater than the first temperature and is equal to or lower than 330° C. . The method according to claim 1 , wherein the third temperature is equal to or greater than 330° C. and lower than 450° C.

7. The method according to claim 1, wherein: The method also includes forming the first conductive layer on the cylindrical substrate.

8. The method of claim 7, wherein the crystallized metal oxide insulating layer comprises a plurality of crystals uniformly arranged in a plurality of lines.

9. The method according to claim 1, wherein: The method also includes forming the first conductive layer on the cylindrical substrate, and etching the cylindrical substrate to form the first conductive layer into a hollow cylindrical shape.

10. The method according to claim 9, wherein: Forming the metal oxide insulating layer includes forming an outer metal oxide insulating layer and an inner metal oxide insulating layer on the outer surface and the inner surface of the first conductive layer having the hollow cylindrical shape, respectively; Forming the second conductive layer includes forming an outer second conductive layer on the outer metal oxide insulating layer and forming an inner second conductive layer on the inner metal oxide insulating layer; as well as Forming the insulating layer includes forming an outer insulating layer on the outer second conductive layer and forming an inner insulating layer on the inner second conductive layer. 11 . The method of claim 10 , wherein the crystallized metal oxide insulating layer comprises a plurality of crystals uniformly arranged in a plurality of lines. 12 . The method of claim 1 , wherein the first conductive layer comprises titanium, aluminum, titanium nitride, or a combination thereof, and the second conductive layer comprises titanium, aluminum, titanium nitride, or a combination thereof.

13. A method of forming a capacitor, characterized in that: include: forming a metal oxide insulating layer on the first conductive layer at a first temperature equal to or greater than 180° C.; forming a second conductive layer on the metal oxide insulating layer at a second temperature ranging from 280° C. to 330° C.; and An insulating layer is formed on the second conductive layer at a third temperature lower than 450° C., wherein the third temperature is greater than the second temperature, and the second temperature is greater than the first temperature. 14 . The method according to claim 13 , wherein before forming the insulating layer, the metal oxide insulating layer is amorphous, and after forming the insulating layer, the metal oxide insulating layer is crystalline.

15. The method of claim 13, wherein the metal oxide insulating layer comprises hafnium zirconium oxide, zirconium oxide, hafnium oxide, titanium oxide, or a combination thereof.

16. The method according to claim 14, wherein: The method also includes forming the first conductive layer on the cylindrical substrate. 17 . The method of claim 16 , wherein the crystallized metal oxide insulating layer comprises a plurality of crystals uniformly arranged in a plurality of lines.

18. The method according to claim 14, wherein: The method also includes forming the first conductive layer on the cylindrical substrate, and etching the cylindrical substrate to form the first conductive layer into a hollow cylindrical shape.

19. The method of claim 18, wherein: Forming the metal oxide insulating layer includes forming an outer metal oxide insulating layer and an inner metal oxide insulating layer on the outer surface and the inner surface of the first conductive layer having the hollow cylindrical shape, respectively; Forming the second conductive layer includes forming an outer second conductive layer on the outer metal oxide insulating layer and forming an inner second conductive layer on the inner metal oxide insulating layer; as well as Forming the insulating layer includes forming an outer insulating layer on the outer second conductive layer and forming an inner insulating layer on the inner second conductive layer.

20. The method of claim 19, wherein the crystallized metal oxide insulating layer comprises a plurality of crystals uniformly arranged in a plurality of lines.

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