TWI879709B - Method of forming capacitor - Google Patents

Abstract

The present disclosure provides a method of forming a capacitor. The method includes the following operations. A first conductive layer is formed on a side surface of a cylindrical substrate. A dielectric layer is formed on the first conductive layer. A metal nitride layer is formed on the dielectric layer. The metal nitride layer is converted to a metal oxynitride layer under an ozone environment. A second conductive layer is formed on the metal oxynitride layer.

Description

Method of forming a capacitor

The present disclosure relates to a method of forming a capacitor.

As the size of semiconductor devices becomes smaller and smaller, the manufacturing processes related to semiconductor devices are becoming more and more complex and challenging. For example, for capacitors in dynamic random access memory (DRAM), how to reduce their size while retaining high capacitance and avoiding leakage current has become a problem that must be solved. Therefore, it is necessary to develop a method for forming capacitors that not only has a high capacitance value but also avoids leakage current.

The present disclosure provides a method for forming a capacitor. The method includes the following operations: forming a first conductive layer on a side surface of a cylindrical substrate; forming a dielectric layer on the first conductive layer; forming a metal nitride layer on the dielectric layer; converting the metal nitride layer into a metal oxynitride layer in an ozone environment; and forming a second conductive layer on the metal oxynitride layer.

In some embodiments, the ozone concentration in the ozone environment is between 50 g/m ³ and 500 g/m ³ .

In some embodiments, the temperature in the ozone environment is between 200°C and 400°C.

In some embodiments, the number of oxygen atoms in the metal oxynitride layer accounts for 50% to 90% of the total number of atoms in the metal oxynitride layer.

In some embodiments, the number of oxygen atoms in the metal oxynitride layer accounts for 50% to 70% of the total number of atoms in the metal oxynitride layer.

In some embodiments, the metal nitride layer includes titanium nitride, and the metal oxynitride layer includes titanium oxynitride.

In some embodiments, the dielectric layer includes zirconium dioxide, tantalum dioxide, aluminum oxide, silicon oxide, rhodium oxide, ruthenium oxide, or a combination thereof.

In some embodiments, the metal oxynitride layer has a thickness in a range of 0.3 nm to 3 nm.

In some embodiments, the thickness of the metal nitride layer is between 0.3 nm and 3 nm.

In some embodiments, the method further includes the following operations. After forming the first conductive layer on the side surface of the cylindrical substrate, removing the cylindrical substrate to form a hollow cylindrical first conductive layer, wherein forming the dielectric layer on the first conductive layer includes forming an inner dielectric layer on the inner surface of the first conductive layer and forming an outer dielectric layer on the outer surface of the first conductive layer, and forming the metal nitride layer on the dielectric layer includes forming an inner metal nitride layer on the inner dielectric layer and forming an outer metal nitride layer. A metal nitride layer is formed on the outer dielectric layer, converting the metal nitride layer into a metal oxynitride layer in an ozone environment includes converting the inner metal nitride layer into an inner metal oxynitride layer and converting the outer metal nitride layer into an outer metal oxynitride layer, and forming a second conductive layer on the metal oxynitride layer includes forming an inner second conductive layer on the inner metal oxynitride layer and forming an outer second conductive layer on the outer metal oxynitride layer.

The embodiments, features and advantages of the present disclosure can be better understood by referring to the following description and the attached patent scope. It should be understood that the general description above and the specific description below are exemplary and explanatory, and are intended to provide further explanation of the present disclosure.

In order to make the description of the present disclosure more detailed and complete, the following is an illustrative description of the implementation mode and the specific implementation mode. It should be noted that this does not limit the implementation mode of the present disclosure to a single form. The implementation modes of the present disclosure can be combined or replaced with each other when beneficial, and other implementation modes can be added without further description.

In addition, spatially relative terms, such as above or below, etc., may be used in this disclosure to describe the relationship of one element or feature to another element or feature in the figure. Spatially relative terms are intended to cover different orientations of the device when in use or operation in addition to the orientation described in the figure. For example, the device may be oriented in other ways, such as rotated 90 degrees or in other orientations, so the spatially relative terms of this disclosure may be interpreted accordingly. In this disclosure, unless otherwise specified, the same element number in different figures refers to the same or similar elements formed by the same or similar methods with the same or similar materials.

In addition, considering the errors caused by measurement or the errors caused by actual operation, the "about", "approximately", "substantially" or "substantially" in the present disclosure include the values or features and the values or features within the deviation range acceptable to the ordinary skilled person in the art. For example, the values within the deviation range of ±15%, ±10% or ±5%. The acceptable deviation range can be selected according to the measurement properties or other properties affecting the operation.

The present disclosure provides a method for forming a capacitor. The method includes the following operations: forming a dielectric layer on a first conductive layer; forming a metal nitride layer on the dielectric layer; converting the metal nitride layer into a metal oxynitride layer in an ozone environment; and forming a second conductive layer on the metal oxynitride layer. Next, the method for forming a capacitor according to the present disclosure is described in detail according to an implementation method.

FIG. 1 is a flow chart of a method 100 for forming a capacitor according to some embodiments. In FIG. 1, method 100 includes operation 101, operation 102, operation 103, and operation 104. FIG. 1 may be read in conjunction with the preferred embodiments further described below, such as the first embodiment of FIGS. 2 to 5, the second embodiment of FIGS. 6A to 10B, and the third embodiment not shown separately. It should be noted that although the third embodiment is not shown separately, the similar drawings of the second embodiment may be referred to, and the differences will be described separately.

In the method 100 of FIG. 1 , operation 101 includes forming a dielectric layer 203 on a first conductive layer 202, for example, referring to FIG. 2 or FIGS. 6A to 8B. The first conductive layer 202 will be used together with a second conductive layer 206 formed in a subsequent operation as electrodes located on both sides of the dielectric layer 203 in a capacitor to charge and discharge the dielectric layer 203. In some embodiments, the method 100 further includes forming the first conductive layer 202 on a substrate before performing operation 101. In some embodiments, the substrate includes a flat substrate (such as the first embodiment further described below) or a cylindrical substrate (such as the second and third embodiments further described below), etc.

Continuing with operation 101 of FIG. 1 , in some embodiments, the preferred first conductive layer 202 includes titanium nitride. In some embodiments, the preferred dielectric layer 203 includes zirconium dioxide, tantalum dioxide, aluminum oxide, silicon oxide, rhodium oxide, ruthenium oxide, or a combination thereof to have a higher dielectric constant. In some embodiments, forming the dielectric layer 203 on the first conductive layer 202 includes any suitable process, such as atomic layer deposition (ALD) method.

In the method 100 of FIG. 1 , operation 102 includes forming a metal nitride layer 204 on the dielectric layer 203, such as referring to FIG. 3 or FIGS. 8A to 8B. The metal nitride layer 204 will form a metal oxynitride layer 205 in a subsequent operation to prevent the capacitor from leaking.

Continuing with the description of operation 102 of FIG. 1 , in some embodiments, the thickness T1 of the metal nitride layer 204 is preferably between 0.3 nm and 3 nm, such as 0.3 nm, 0.5 nm, 1.0 nm, 1.5 nm, 2.0 nm, 2.5 nm, or 3.0 nm. If the thickness T1 of the metal nitride layer 204 is too small, the thickness T2 of the formed metal nitride oxide layer 205 will also be too small, so that the effect of reducing leakage of the capacitor is reduced. If the thickness T1 of the metal nitride layer 204 is too large, the distance between the second conductive layer 206 to be formed in the subsequent operation and the dielectric layer 203 is too far, so it is more difficult to charge and discharge the dielectric layer 203 through the second conductive layer 206. In some embodiments, the preferred metal nitride layer 204 includes titanium nitride. In some embodiments, forming the metal nitride layer 204 on the dielectric layer 203 includes any suitable process, such as atomic layer deposition.

In the method 100 of FIG. 1 , operation 103 includes converting the metal nitride layer 204 into the metal oxynitride layer 205 in an ozone environment, for example, referring to FIGS. 3 to 4 or FIGS. 8A to 9B. The metal oxynitride layer 205 can prevent the atoms (e.g., oxygen atoms) in the dielectric layer 203 from migrating into the second conductive layer 206 when the second conductive layer 206 to be formed in a subsequent operation directly contacts the dielectric layer 203, thereby causing atomic vacancies in the dielectric layer 203 and causing leakage. In some embodiments, the metal nitride layer 204 is placed in an ozone environment including ozone to form the metal oxynitride layer 205.

Continuing to explain operation 103 of FIG. 1, operation 103 can also adjust the ratio of the number of different atoms in the metal oxynitride layer 205 to optimize the reduction of the leakage of the capacitor. For example, the ratio of the number of oxygen atoms in the metal nitride layer 204 to the total number of atoms is a first ratio of the number of oxygen atoms. After completing operation 103, the ratio of the number of oxygen atoms in the metal oxynitride layer 205 to the total number of atoms is a second ratio, and the second ratio is greater than the first ratio. For example, the ratio of the number of nitrogen atoms in the metal nitride layer 204 to the total number of atoms is a first ratio of the number of nitrogen atoms. After completing operation 103, the ratio of the number of nitrogen atoms in the metal oxynitride layer 205 to the total number of atoms is a second ratio, and the second ratio is less than the first ratio. In some embodiments, the number of oxygen atoms in the metal oxynitride layer 205 is preferably 50% to 90% of the total number of atoms, such as 50%, 60%, 70%, 80% or 90%, and more preferably 50% to 70%, such as 55%, 60%, 65% or 70%.

Continuing with the description of operation 103 of FIG. 1 , in some embodiments, a preferred thickness T2 of the metal oxynitride layer 205 is between 0.3 nm and 3 nm, such as 0.3 nm, 0.5 nm, 1.0 nm, 1.5 nm, 2.0 nm, 2.5 nm, or 3.0 nm. If the thickness T2 of the metal oxynitride layer 205 is too small, the effect of reducing capacitor leakage will be reduced. If the thickness T2 of the metal oxynitride layer 205 is too large, the distance between the second conductive layer 206 formed in the subsequent operation and the dielectric layer 203 will be too far, so it is difficult to charge and discharge the dielectric layer 203 through the second conductive layer 206.

Continuing with operation 103 of FIG. 1 , in some embodiments, a preferred ozone concentration in the ozone environment is 50 g/m ³ to 500 g/m ³ , such as 50 g/m ³ , 100 g/m ³ , 150 g/m ³ , 200 g/m ³ , 250 g/m ³ , 300 g/m ³ , 350 g/m ³ , 400 g/m ³ , 450 g/m ³ or 500 g/m ³ , more preferably 100 g/m ³ to 200 g/m ³ . Too little or too much ozone concentration may cause the ratio of the number of atoms in the metal oxynitride layer 205 to be inconsistent with expectations. In some embodiments, the preferred temperature in the ozone environment is 200°C to 400°C, such as 200°C, 250°C, 300°C, 350°C or 400°C, more preferably 250°C to 300°C. In some embodiments, the metal oxynitride layer 205 includes titanium oxynitride. Too low or too high a temperature may cause the ratio of the number of atoms in the metal oxynitride layer 205 to be undesirable.

In the method 100 of FIG. 1 , operation 104 includes forming a second conductive layer 206 on the metal oxynitride layer 205, such as referring to FIG. 5 or FIG. 10A-10B. The second conductive layer 206 and the first conductive layer 202 serve as electrodes in the capacitor as described above.

Continuing with operation 104 of FIG. 1 , in some embodiments, the thickness T3 of the second conductive layer 206 is preferably greater than 3 nm to charge and discharge the dielectric layer 203 well. In some embodiments, the second conductive layer 206 comprises titanium nitride. In some embodiments, forming the second conductive layer 206 on the metal oxynitride layer 205 comprises any suitable process, such as atomic layer deposition.

Next, the method 100 of FIG. 1 is further described with reference to the first embodiment of FIG. 2 to FIG. 5 , wherein the capacitor of the first embodiment is formed in a planar shape.

In the first embodiment, before performing the operation 101 described above, a first conductive layer 202 is formed on the upper surface of the flat substrate 201P, for example, referring to FIG. 2. In some embodiments, the flat substrate 201P includes active elements (such as transistors or diodes, etc.), passive elements (such as capacitors, resistors or inductors, etc.) or wires, etc., which are not shown in the figure, so that the capacitor formed on the flat substrate 201P can be connected to other elements of the flat substrate 201P. In some embodiments, the flat substrate 201P includes any suitable semiconductor material, such as carbon, silicon, germanium, silicon carbide, boron nitride, aluminum nitride, gallium nitride, gallium phosphide, gallium arsenide, indium phosphide, indium arsenide, indium arsenide, zinc oxide, SiGe, AlGaAs, InGaAs, InGaP, AlInAs, GaAsP, AlGaN, InGaN, AlGaInP, the like, or a combination thereof. In some embodiments, forming the first conductive layer 202 on the flat substrate 201P includes any suitable process, such as atomic layer deposition, etc.

In the first embodiment, when performing the above-mentioned operation 101 (for example, refer to FIG. 2), operation 102 (for example, refer to FIG. 3), operation 103 (for example, refer to FIGS. 3 to 4), and operation 104 (for example, refer to FIG. 5), since the flat substrate 201P is in a flat shape, the first conductive layer 202, the dielectric layer 203, the metal nitride layer 204, the metal oxynitride layer 205, and the second conductive layer 206 formed on the flat substrate 201P are basically in a flat shape with the flat substrate 201P, and the capacitor finally formed is in a flat shape.

Next, the method 100 of FIG. 1 is further described with reference to a second embodiment shown in FIGS. 6A to 10B , wherein the capacitor of the second embodiment is formed in a cylindrical shape.

In the second embodiment, before performing the operation 101 described above, a first conductive layer 202 is formed on the side surface of the cylindrical substrate 201C, and then the cylindrical substrate 201C is removed, so that the first conductive layer 202 forms a hollow cylindrical shape and has an exposed inner surface 202I and an outer surface 202O, for example, refer to FIGS. 6A to 7B. In some embodiments, the cylindrical substrate 201C includes but is not limited to silicon or silicon dioxide. In some embodiments, forming the first conductive layer 202 on the cylindrical substrate 201C includes any suitable process, such as atomic layer deposition. In some embodiments, removing the cylindrical substrate 201C includes any suitable process, such as dry etching or wet etching.

In the second embodiment, when performing the above-described operations 101 (e.g., referring to FIGS. 8A to 8B), 102 (e.g., referring to FIGS. 8A to 8B), 103 (e.g., referring to FIGS. 8A to 9B), and 104 (e.g., referring to FIGS. 10A to 10B), since the first conductive layer 202 has an inner surface 202I and an outer surface 202O, forming the dielectric layer 203 on the first conductive layer 202 includes forming an inner dielectric layer 203A on the inner surface 202I of the first conductive layer 202 and forming an outer dielectric layer 203B on the outer surface 202O of the first conductive layer 202; forming the metal nitride layer 204 on the dielectric layer 204; and forming the metal nitride layer 204 on the dielectric layer 204. 03 includes forming an inner metal nitride layer 204A on the inner dielectric layer 203A and forming an outer metal nitride layer 204B on the outer dielectric layer 203B, converting the metal nitride layer 204 into a metal nitride oxide layer 205 in an ozone environment, and converting the inner metal nitride layer 204A into the inner metal nitride oxide layer 205. A and converting the outer metal nitride layer 204B into an outer metal oxynitride layer 205B; and forming the second conductive layer 206 on the metal oxynitride layer 205 includes forming an inner second conductive layer 206A on the inner metal oxynitride layer 205A and forming an outer second conductive layer 206B on the outer metal oxynitride layer 205B.

In the second embodiment, a first conductive layer 202, a dielectric layer 203 (including two separated inner dielectric layers 203A and an outer dielectric layer 203B), a metal nitride layer 204 (including two separated inner metal nitride layers 204A and an outer metal nitride layer 204B), a metal oxynitride layer 205 (including two separated inner metal nitride layers 204A and an outer metal nitride layer 204B) are formed on a cylindrical substrate 201C. The inner metal oxynitride layer 205A and the outer metal oxynitride layer 205B separated from each other) and the second conductive layer 206 (including two separated inner second conductive layers 206A and outer second conductive layers 206B) are all hollow cylindrical or the inner second conductive layer 206A is also cylindrical (as shown in FIGS. 10A to 10B), and the capacitor finally formed is also cylindrical. The cylindrical capacitor can have a higher aspect ratio, thereby increasing the integration density of semiconductor devices (such as dynamic random access memory, etc.). In addition, the dielectric layer 203 includes two separated inner dielectric layers 203A and outer dielectric layers 203B, which can further increase the capacitance value of the capacitor.

In the second embodiment, the features (e.g., formation materials, formation methods, thickness, atomic ratio, etc.) of the inner dielectric layer 203A and the outer dielectric layer 203B, the inner metal nitride layer 204A and the outer metal nitride layer 204B, the inner metal oxynitride layer 205A and the outer metal oxynitride layer 205B, and the inner second conductive layer 206A and the outer second conductive layer 206B are substantially the same as the features (e.g., formation materials, formation methods, thickness, atomic ratio, etc.) of the dielectric layer 203, the metal nitride layer 204, the metal oxynitride layer 205, and the second conductive layer 206 described above. Therefore, please refer to the above for details, and no further description is given here.

Next, the method 100 of FIG. 1 is further described with reference to a third embodiment, wherein the capacitor of the third embodiment is formed into a cylindrical shape. Although the third embodiment is not shown separately, it is similar to the second embodiment, and thus reference may be made to FIGS. 6A to 10B of the second embodiment, and the differences will be described separately.

In the third embodiment, before performing the operation 101 described above, a first conductive layer 202 is formed on the side surface of the cylindrical substrate 201C so that the first conductive layer 202 forms a hollow cylindrical shape, for example, similar FIGS. 6A to 6B can be referred to. It should be noted that the difference between the third embodiment and the second embodiment is that the third embodiment does not remove the cylindrical substrate 201C. In some embodiments, the cylindrical substrate 201C includes but is not limited to silicon or silicon dioxide. In some embodiments, forming the first conductive layer 202 on the cylindrical substrate 201C includes any suitable process, such as atomic layer deposition.

In the third embodiment, after performing the above-described operation 101 (for example, similar FIGS. 8A to 8B may be referred to, except that the inner side of the first conductive layer 202 is a cylindrical substrate 201C as shown in FIGS. 6A to 6B), operation 102 (for example, similar FIGS. 8A to 8B may be referred to, except that the inner side of the first conductive layer 202 is a cylindrical substrate 201C as shown in FIGS. 6A to 6B), operation 103 (for example, similar FIGS. 8A to 9B may be referred to, except that the inner side of the first conductive layer 202 is a cylindrical substrate 201C as shown in FIGS. 6A to 6B), operation 104 (for example, similar FIGS. 8A to 9B may be referred to, except that the inner side of the first conductive layer 202 is a cylindrical substrate 201C as shown in FIGS. 6A to 6B) and operation 105 (for example, similar FIGS. 8A to 9B may be referred to, except that the inner side of the first conductive layer 202 is a cylindrical substrate 201C as shown in FIGS. B) and operation 104 (for example, similar FIGS. 10A to 10B can be referred to, but the inner side of the first conductive layer 202 is the cylindrical substrate 201C as shown in FIGS. 6A to 6B), since the cylindrical substrate 201C is cylindrical, the first conductive layer 202, the dielectric layer 203, the metal nitride layer 204, the metal oxynitride layer 205 and the second conductive layer 206 formed on the cylindrical substrate 201C basically have a hollow cylindrical shape, and the capacitor finally formed is cylindrical. The cylindrical capacitor can have a higher aspect ratio, thereby increasing the integration density of the semiconductor device (such as dynamic random access memory, etc.).

The capacitor formed by the method of forming a capacitor disclosed in the present invention has high capacitance and prevents leakage. Moreover, the capacitor formed by the present invention has various forms and the process is simple. It is not only compatible with various semiconductor processes, but also can be applied in various semiconductor devices with increasingly smaller sizes.

The present disclosure describes some embodiments in considerable detail, but other embodiments may also be possible, and thus the description of the embodiments contained in the present disclosure should not limit the scope and spirit of the appended patent applications.

For those with ordinary knowledge in the art, modifications and changes can be made to the present disclosure without departing from the spirit and scope of the present disclosure. As long as the above modifications and changes are within the scope and spirit of the attached patent application, the present disclosure covers these modifications and changes.

100: method 101: operation 102: operation 103: operation 104: operation 201C: cylindrical substrate 201P: flat substrate 202: first conductive layer 202I: inner surface 202O: outer surface 203: dielectric layer 203A: inner dielectric layer 203B: outer dielectric layer 204: metal nitride layer 204A: inner metal nitride layer 204B: outer metal nitride layer 205: metal oxynitride layer 205A: inner metal oxynitride layer 205B: outer metal oxynitride layer 206: Second conductive layer 206A: Inner second conductive layer 206B: Outer second conductive layer T1: Thickness T2: Thickness T3: Thickness

When reading the drawings of the present disclosure, it is recommended to understand the various aspects of the present disclosure from the detailed description below. It should be noted that in accordance with standard industry practices, the sizes of various components may not be drawn to scale. In addition, in order to make the description clearer, the sizes of various components may be increased or reduced. Figure 1 is a flow chart of a method for forming a capacitor according to some embodiments of the present disclosure. Figures 2 to 5 are cross-sectional views of a capacitor in the intermediate process of forming a capacitor according to the first embodiment of the present disclosure. Figures 6A, 7A, 8A, 9A and 10A are top views of a capacitor in the intermediate process of forming a capacitor according to the second embodiment of the present disclosure. Figures 6B, 7B, 8B, 9B and 10B are cross-sectional views of capacitors during the intermediate process of forming a capacitor according to the second embodiment of the present disclosure.

Domestic storage information (please note in the order of storage institution, date, and number) None Foreign storage information (please note in the order of storage country, institution, date, and number) None

100:Methods

101: Operation

102: Operation

103: Operation

104: Operation

Claims (10)

A method for forming a capacitor, comprising: forming a first conductive layer on a side surface of a cylindrical substrate; forming a dielectric layer on the first conductive layer; forming a metal nitride layer on the dielectric layer; converting the metal nitride layer into a metal oxynitride layer in an ozone environment; and forming a second conductive layer on the metal oxynitride layer. The method of claim 1, wherein an ozone concentration in the ozone environment is between 50 g/m ³ and 500 g/m ³ . A method as described in claim 1, wherein a temperature in the ozone environment is between 200°C and 400°C. The method as described in claim 1, wherein the number of oxygen atoms in the metal oxynitride layer accounts for 50% to 90% of the total number of atoms in the metal oxynitride layer. A method as described in claim 4, wherein the number of oxygen atoms in the metal oxynitride layer accounts for 50% to 70% of the total number of atoms in the metal oxynitride layer. The method of claim 1, wherein the metal nitride layer comprises titanium nitride, and the metal oxynitride layer comprises titanium oxynitride. The method of claim 1, wherein the dielectric layer comprises zirconium dioxide, tantalum dioxide, aluminum oxide, silicon oxide, rhodium oxide, ruthenium oxide or a combination thereof. The method of claim 1, wherein the metal oxynitride layer has a thickness of 0.3 nm to 3 nm. The method of claim 1, wherein the metal nitride layer has a thickness of 0.3 nm to 3 nm. The method as described in claim 1 further includes removing the cylindrical substrate after forming the first conductive layer on the side surface of the cylindrical substrate to form a hollow cylindrical first conductive layer, wherein: Forming the dielectric layer on the first conductive layer includes: forming an inner dielectric layer on an inner surface of the first conductive layer, and forming an outer dielectric layer on an outer surface of the first conductive layer; Forming the metal nitride layer on the dielectric layer includes: forming an inner metal nitride layer on the inner dielectric layer, and forming an outer metal nitride layer on the outer dielectric layer; Converting the metal nitride layer to the metal oxynitride layer in the ozone environment includes: converting the inner metal nitride layer to an inner metal oxynitride layer, and converting the outer metal nitride layer to an outer metal oxynitride layer; and Forming the second conductive layer on the metal oxynitride layer includes: forming an inner second conductive layer on the inner metal oxynitride layer, and forming an outer second conductive layer on the outer metal oxynitride layer.

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