Method for forming electrode layer of DTC
After forming a dielectric layer on the deep trench surface of DTC, the first titanium nitride layer is first formed at a high temperature, and then the second titanium nitride layer is formed at a low temperature, which solves the filling defect problem of the ALD process when filling the deep trench, and improves the step coverage and conformity of the metal electrode layer.
Patent Information
- Application Number
- CN202510213200.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-02-25
- Publication Date
- 2025-05-16
AI Technical Summary
During the metal electrode production process of deep trench capacitors (DTC), the atomic layer deposition (ALD) process is prone to filling the deep trench defects, affecting the capacitance density and step coverage of the electrode layer.
After forming a dielectric layer on the deep groove surface of DTC, a first titanium nitride layer is first formed by the ALD process at a high temperature, and then a second titanium nitride layer is formed at a relatively low temperature to form a metal electrode layer of DTC.
This method uses the deposited film layer under high temperature conditions to discharge water vapor in deep trenches, enhance the gas diffusion ability, and form a first titanium nitride layer with better conformity as the seed layer of the second titanium nitride layer, thereby improving the step coverage of the metal electrode layer and reducing the probability of defects.
Smart Images
Figure CN120018521A_ABST
Abstract
Description
Technical Field
[0001] The present application relates to the technical field of semiconductor devices and integrated circuits, and in particular to a method for forming an electrode layer of a DTC. Background Art
[0002] Compared with traditional planar capacitors, deep trench capacitors (DTCs) have a three-dimensional structure and can achieve ultra-high capacitance density, thus being widely used. Generally, DTCs are composed of metal electrodes and high-k dielectric layers (dielectrics with a dielectric constant greater than 3). After alternately depositing metal layers and high-k dielectric layers in the trenches for multiple times, parallel capacitors are formed through metal interconnections, thereby further improving capacitance density.
[0003] In the process of making the metal electrode of DTC, the atomic layer deposition (ALD) process is usually used to deposit the titanium nitride (TiN) layer as the metal electrode of the capacitor. However, although the ALD process has a higher step coverage rate than the physical vapor deposition (PVD) process and the metal-organic chemical vapor deposition (MOCVD) process, it still has a high filling defect when filling the deep trench of DTC (the ratio of its depth to width is much greater than 10:1). Summary of the invention
[0004] The present application provides a method for forming a metal layer of a DTC, which can solve the problem that the method for forming an electrode layer of a DTC provided in the related art is prone to defects. The method comprises:
[0005] forming a dielectric layer on the surface of a deep trench, wherein the deep trench is formed in an interlayer dielectric layer, and the deep trench is a trench having a ratio of depth to width greater than 20;
[0006] forming a first titanium nitride layer by an ALD process at a first temperature,
[0007] A second titanium nitride layer is formed by an ALD process at a second temperature, the first titanium nitride layer and the second titanium nitride layer constitute an electrode layer of the DTC, and the first temperature is greater than the second temperature.
[0008] In some embodiments, the first temperature ranges from 370 degrees Celsius to 470 degrees Celsius.
[0009] In some embodiments, the second temperature ranges from 300 degrees Celsius to 370 degrees Celsius.
[0010] In some embodiments, the first titanium nitride layer and the second titanium nitride layer have the same thickness.
[0011] In some embodiments, the interlayer dielectric layer includes a plasma enhanced oxide layer.
[0012] In some embodiments, the dielectric layer includes a silicon dioxide layer.
[0013] The technical solution of this application has at least the following advantages:
[0014] In the process of making DTC, after forming the dielectric layer on the surface of the deep groove of DTC, a first titanium nitride layer is first formed by an ALD process at high temperature, and then a second titanium nitride layer is formed by an ALD process at a relatively low temperature to constitute a metal layer of DTC. Since the thin film layer is deposited under high temperature conditions, the water vapor in the deep groove can be discharged, which is equivalent to a degassing process. At the same time, the gas diffusion ability under high temperature conditions is stronger, which can make the reaction gas diffuse to the bottom area of the deep groove. Therefore, the first titanium nitride layer formed has better conformality, which can be used as a seed layer for the second titanium nitride layer formed subsequently, so that the metal electrode layer finally formed has a higher step coverage, reducing the probability of defects caused by growing metal electrodes in deep trenches. BRIEF DESCRIPTION OF THE DRAWINGS
[0015] In order to more clearly illustrate the specific implementation methods of the present application or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.
[0016] Figure 1 is a flow chart of a method for forming an electrode layer of a DTC provided by an exemplary embodiment of the present application;
[0017] Figure 2 It is a cross-sectional schematic diagram of a DTC after the electrode layer is formed according to an exemplary embodiment of the present application. DETAILED DESCRIPTION
[0018] The following will be combined with the accompanying drawings to clearly and completely describe the technical solutions in this application. Obviously, the described embodiments are part of the embodiments of this application, not all of them. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.
[0019] In the description of the present application, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present application. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.
[0020] In the description of this application, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, it can also be the internal connection of two components, it can be a wireless connection, or it can be a wired connection. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.
[0021] In addition, the technical features involved in the different embodiments of the present application described below can be combined with each other as long as they do not conflict with each other.
[0022] refer to Figure 1 , which shows a flow chart of a method for forming an electrode layer of a DTC provided by an exemplary embodiment of the present application, such as Figure 1 As shown, the method includes:
[0023] Step S1, forming a dielectric layer on the interlayer dielectric layer and the surface of the deep trench, wherein the deep trench is formed in the interlayer dielectric layer, and the deep trench is a trench with a ratio of depth to width greater than 20.
[0024] The dielectric layer may be a silicon dioxide (SiO2) layer, and the silicon dioxide layer may be deposited on the inter-layer dielectric (ILD) layer and the surface of the deep trench by an ALD process.
[0025] Step S2, forming a first titanium nitride layer by an ALD process at a first temperature.
[0026] Step S3, forming a second titanium nitride layer by an ALD process at a second temperature, the first titanium nitride layer and the second titanium nitride layer constitute an electrode layer of the DTC, and the first temperature is greater than the second temperature.
[0027] refer to Figure 2 , which shows a cross-sectional schematic diagram after forming the first titanium nitride layer and the second titanium nitride layer. Figure 2As shown, a deep trench is formed in the interlayer dielectric layer 210, and the ratio of the depth H to the width W of the deep trench is greater than 20. The interlayer dielectric layer 210 is formed on the wafer ( Figure 2 The wafer is used to form a semiconductor device, the interlayer dielectric layer 210 may include a plasma enhanced oxide (PEOX) layer, a dielectric layer 220 is formed on the interlayer dielectric layer 210 and the surface of the deep trench, a first titanium nitride layer 231 may be formed by an ALD process at a first temperature, and a second titanium nitride layer 232 may be formed by an ALD process at a second temperature, and the first temperature is greater than the second temperature.
[0028] Optionally, the first temperature ranges from 370 degrees Celsius (°C) to 470 degrees Celsius, and the second temperature ranges from 300 degrees Celsius to 370 degrees Celsius. The thickness of the first titanium nitride layer 231 and the second titanium nitride layer 232 are the same (the thickness can be set according to actual production requirements, and here setting the thickness of the first titanium nitride layer 231 and the second titanium nitride layer 232 to be the same is an optional implementation).
[0029] To summarize, in the embodiment of the present application, during the manufacturing process of DTC, after forming the dielectric layer on the surface of the deep groove of the DTC, a first titanium nitride layer is first formed by a high-temperature ALD process, and then a second titanium nitride layer is formed by a relatively low-temperature ALD process to constitute a metal layer of the DTC. Since the thin film layer is deposited under high-temperature conditions, the water vapor in the deep groove can be discharged, which is equivalent to a degassing process. At the same time, the gas diffusion ability under high-temperature conditions is stronger, and the reaction gas can diffuse to the bottom area of the deep groove. Therefore, the first titanium nitride layer formed has better conformality, which can be used as a seed layer for the second titanium nitride layer formed subsequently, so that the metal electrode layer finally formed has a higher step coverage, thereby reducing the probability of defects caused by growing metal electrodes in the deep trenches.
[0030] Obviously, the above embodiments are merely examples for the purpose of clear explanation, and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived therefrom are still within the scope of protection created by this application.
Claims
1. A method for forming an electrode layer of a DTC, characterized in that: include: forming a dielectric layer on the surface of a deep trench, wherein the deep trench is formed in an interlayer dielectric layer, and the deep trench is a trench having a ratio of depth to width greater than 20; forming a first titanium nitride layer by an ALD process at a first temperature, A second titanium nitride layer is formed by an ALD process at a second temperature, the first titanium nitride layer and the second titanium nitride layer constitute an electrode layer of the DTC, and the first temperature is greater than the second temperature.
2. The method according to claim 1, characterized in that The first temperature ranges from 370 degrees Celsius to 470 degrees Celsius.
3. The method according to claim 2, characterized in that The second temperature ranges from 300 degrees Celsius to 370 degrees Celsius.
4. The method according to claim 3, characterized in that The first titanium nitride layer and the second titanium nitride layer have the same thickness.
5. The method according to any one of claims 1 to 4, characterized in that: The interlayer dielectric layer includes a plasma enhanced oxide layer. The method according to claim 5 , wherein the dielectric layer comprises a silicon dioxide layer.