Method of forming high-k dielectric layer
By first growing an alumina seed layer on the barrier layer and adjusting the pulse time of the ALD process, the problems of slow growth rate and poor stability of the ALD process were solved, achieving efficient film formation of high-k dielectric layers and improving product reliability.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- HUA HONG SEMICON WUXI LTD
- Filing Date
- 2026-03-30
- Publication Date
- 2026-07-10
Smart Images
Figure CN122373368A_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of semiconductor devices and integrated circuit technology, and in particular to a method for forming a high-k dielectric layer. Background Technology
[0002] Atomic layer deposition (ALD) is a process for forming high-quality thin films with atomic-scale thickness. In the semiconductor integrated circuit manufacturing industry, it is commonly used to prepare high-dielectric-constant dielectric (dielectric material with a dielectric constant k greater than 8, hereinafter referred to as "high-k dielectric") films. Among these, hafnium oxide (HfO) thin films are a commonly used high-k dielectric and can be used as the dielectric layer for front-end devices and / or back-end metal-insulator-metal (MIM) capacitors.
[0003] However, the growth rate of high-k dielectric layers grown by ALD process is relatively slow, especially the dielectric layer used as a MIM capacitor, which usually requires a thickness of more than 30 angstroms. At the same time, the growth rate of ALD process is affected by factors such as the previous dielectric layer, reaction mode, density of active reaction sites on the dielectric surface, and reaction temperature. Both the growth rate and stability have defects, which reduces the production efficiency of device products. Summary of the Invention
[0004] This application provides a method for forming a high-k dielectric layer, which can solve the problems of low growth rate and poor film stability of high-k dielectric layers grown by ALD process in related technologies. The method includes: The wafer is transferred to the process chamber of the ALD machine, the wafer being used to fabricate semiconductor devices, and a barrier layer is formed on top of the wafer; An alumina seed layer is grown on the barrier layer using the ALD process. The growth of the alumina seed layer requires n operation cycles, where n is a natural number and n≥1. A high-k dielectric layer is grown on the alumina seed layer using the ALD process. The high-k dielectric layer comprises a dielectric material with a dielectric constant k greater than 8. The growth of the high-k dielectric layer requires N operation cycles, where N is a natural number and N > n. In this context, the pulse time in the first m work cycles of N work cycles is greater than the pulse time in the subsequent work cycles, where m is a natural number and n < m < N.
[0005] In some embodiments, the high-k dielectric layer comprises a hafnium oxide thin film layer.
[0006] In some embodiments, the thickness of the alumina seed layer is less than 3 angstroms.
[0007] In some embodiments, the growth of a high-k dielectric layer on the alumina seed layer via the ALD process includes: Perform m operation cycles, and within each m operation cycle, introduce a reaction gas containing water vapor and hafnium tetrachloride in a pulsed manner; Perform (Nm) operating cycles, during which a reaction gas containing water vapor and hafnium tetrachloride is introduced in a pulsed manner, and the pulse time in the (Nm) operating cycles is 1 / 3 to 1 / 2 of the pulse time in the m operating cycles.
[0008] In some embodiments, the barrier layer includes a titanium nitride layer and / or a tantalum nitride layer.
[0009] In some embodiments, the barrier layer comprises periodically alternating layers of titanium nitride and tantalum nitride.
[0010] The technical solution of this application has at least the following advantages: By first growing a thin alumina layer (with fewer operation cycles than the pretreatment stage of the high-k dielectric layer) on the barrier layer during the fabrication of the high-k dielectric layer, and then growing the high-k dielectric layer sequentially through pretreatment and cyclic operation, the surface of the alumina seed layer is rich in hydroxyl groups, which can provide reaction sites for the precursor of the high-k dielectric layer. At the same time, the pulse time of the pretreatment stage is greater than the pulse time of the cyclic operation, which can increase the adsorption probability. This improves the growth rate and film stability of the high-k dielectric layer grown by the ALD process, thereby improving production efficiency and product reliability. Attached Figure Description
[0011] To more clearly illustrate the technical solutions in the specific embodiments of this application or the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.
[0012] Figure 1 This is a flowchart of a method for forming a high-k dielectric layer provided in an exemplary embodiment of this application; Figures 2 to 6 This is a schematic diagram illustrating the formation process of a high-k dielectric layer provided in an exemplary embodiment of this application. Detailed Implementation
[0013] The technical solutions of this application will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this application. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.
[0014] In the description of this application, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.
[0015] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal connection of two components; and they can refer to a wireless connection or a wired connection. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.
[0016] Furthermore, the technical features involved in the different embodiments of this application described below can be combined with each other as long as they do not conflict with each other.
[0017] refer to Figure 1 It illustrates a flowchart of a method for forming a high-k dielectric layer according to an exemplary embodiment of this application, such as... Figure 1 As shown, the method includes: Step S1: The wafer is transferred to the process chamber of the ALD machine. The wafer is used to fabricate semiconductor devices and a barrier layer is formed on top of the wafer.
[0018] In this embodiment, if the high-k dielectric layer is the gate dielectric layer of the device, the barrier layer is formed on the upper surface of the wafer; if the high-k dielectric layer is the dielectric layer of the MIM capacitor, the barrier layer is formed on the lower electrode metal layer above the wafer. The following description uses the example of a barrier layer formed on the upper surface of the wafer.
[0019] refer to Figure 2 This shows a schematic cross-sectional view before the formation of the alumina (Al2O3) seed layer. For example, as shown... Figure 2As shown, a barrier layer 221 is formed on the upper surface of wafer 210. The barrier layer 221 may include a titanium nitride (TiN) layer and / or a tantalum nitride (TaN) layer, and the thickness of the barrier layer 221 is 500 Å to 1000 Å.
[0020] Optionally, a barrier layer 221 can be formed by alternating growth of titanium nitride and tantalum nitride layers using physical vapor deposition (PVD) process. After the barrier layer 221 is formed, the wafer 210 with the barrier layer 221 formed is transferred from the process chamber of the PVD machine to the process chamber of the ALD machine.
[0021] Step S2 involves growing an alumina seed layer on the barrier layer using the ALD process. The growth of the alumina seed layer requires n operating cycles, where n is a natural number and n≥1.
[0022] refer to Figure 3 It shows a schematic cross-sectional view of the alumina seed layer; Reference Figure 4 It shows a schematic cross-sectional view after the formation of the alumina seed layer. For example, as shown... Figure 3 and Figure 4 As shown, an alumina seed layer 222 can be grown on the barrier layer 221 over n work cycles. In each work cycle, trimethylaluminium (C3H9Al) and water vapor (H2O) are alternately pulsed to form a thin film layer. Optionally, n ≤ 3; the thickness of the formed alumina seed layer 222 is less than 3 angstroms (e.g., it can be from 0.9 angstroms to 2.8 angstroms).
[0023] Step S3: A high-k dielectric layer is grown on the alumina seed layer using the ALD process. The high-k dielectric layer includes dielectric materials with a dielectric constant k greater than 8. The growth of the high-k dielectric layer requires N operation cycles, where N is a natural number and N > n.
[0024] The following description uses a high-k dielectric layer, including a hafnium oxide layer, as an example. The process of growing a high-k dielectric layer on an alumina seed layer using the ALD process requires N operation cycles, which can be divided into two stages: the first stage is a pretreatment stage, which requires m operation cycles (m is a natural number, n < m < N); the second stage is the thin film growth stage, which requires (Nm) operation cycles. The pulse time of each operation cycle in the first stage is greater than the pulse time of each operation cycle in the second stage; optionally, 2 ≤ m ≤ 4.
[0025] refer to Figure 5 This illustrates a cross-sectional schematic diagram of the preprocessing stage. For example, such as... Figure 5 As shown, the pretreatment stage includes: performing m operation cycles, during which a reaction gas containing water vapor and hafnium tetrachloride (HfCl4) is introduced in a pulse manner, with the pulse time in each operation cycle being t1.
[0026] refer to Figure 6 This illustrates a schematic cross-sectional view after the formation of a high-k dielectric layer. For example, such as... Figure 6 As shown, the thin film growth stage includes: performing (Nm) operation cycles, during which a reaction gas containing water vapor and hafnium tetrachloride is introduced in a pulsed manner to grow a hafnium oxide layer 223. The pulse time in each operation cycle is t2, where t2 < t1. Optionally, (1 / 3)t1 ≤ t2 ≤ (1 / 2)t1, for example, t1 = 1 second (s), t2 = 0.5 seconds.
[0027] In summary, in this embodiment of the application, during the fabrication of the high-k dielectric layer, a thin alumina layer (with fewer operation cycles than the pretreatment stage of the high-k dielectric layer) is first grown on the barrier layer, and then the high-k dielectric layer is grown sequentially through pretreatment and cyclic operation. Since the surface of the alumina seed layer is rich in hydroxyl groups, it can provide reaction sites for the precursor of the high-k dielectric layer. At the same time, the pulse time of the pretreatment stage is greater than the pulse time of the cyclic operation, which can increase the adsorption probability. Thus, the growth rate of the high-k dielectric layer grown by the ALD process is improved, and its film-forming stability is improved, thereby improving production efficiency and product reliability.
[0028] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this application.
Claims
1. A method for forming a high-k dielectric layer, characterized in that, include: The wafer is transferred to the process chamber of the ALD machine, the wafer being used to fabricate semiconductor devices, and a barrier layer is formed on top of the wafer; An alumina seed layer is grown on the barrier layer using the ALD process. The growth of the alumina seed layer requires n operation cycles, where n is a natural number and n≥1. A high-k dielectric layer is grown on the alumina seed layer using the ALD process. The high-k dielectric layer comprises a dielectric material with a dielectric constant k greater than 8. The growth of the high-k dielectric layer requires N operation cycles, where N is a natural number and N > n. In this context, the pulse time in the first m work cycles of N work cycles is greater than the pulse time in the subsequent work cycles, where m is a natural number and n < m < N.
2. The method according to claim 1, characterized in that, The high-k dielectric layer includes a hafnium oxide thin film layer.
3. The method according to claim 2, characterized in that, The thickness of the alumina seed layer is less than 3 angstroms.
4. The method according to claim 3, characterized in that, The process of growing a high-k dielectric layer on the alumina seed layer via ALD includes: Perform m operation cycles, and within each m operation cycle, introduce a reaction gas containing water vapor and hafnium tetrachloride in a pulsed manner; Perform (Nm) operating cycles, during which a reaction gas containing water vapor and hafnium tetrachloride is introduced in a pulsed manner, and the pulse time in the (Nm) operating cycles is 1 / 3 to 1 / 2 of the pulse time in the m operating cycles.
5. The method according to any one of claims 2 to 4, characterized in that, The barrier layer includes a titanium nitride layer and / or a tantalum nitride layer.
6. The method according to claim 5, characterized in that, The barrier layer comprises periodically alternating layers of titanium nitride and tantalum nitride.