Preparation method of SiCN diffusion barrier layer

Abstract

The invention belongs to the technical field of integrated circuit manufacturing, and particularly relates to a preparation method of a SiCN diffusion barrier layer, and the SiCN diffusion barrier layer is prepared from trimethylsilane, deuterated ammonia and disilane through a plasma vapor deposition method. The deuterated ammonia can influence the microstructure and composition of the material in the process of participating in the preparation of the SiCN diffusion barrier layer, so that the defect degree is lower after annealing treatment. Meanwhile, the introduction of disilane promotes the uniform distribution of each reaction gas in the chamber, and reduces the local concentration difference, thereby enabling the surface of the barrier layer to be smoother and smoother, and effectively improving the surface flatness of the barrier layer.

Description

Technical Field

[0001] The invention belongs to the technical field of integrated circuit manufacturing, and in particular relates to a preparation process of a SiCN diffusion barrier layer. Background Art

[0002] With the development of advanced manufacturing processes in the integrated circuit industry, the process technology is constantly approaching the physical limit. The RC delay and crosstalk of the metal interconnection system of the integrated circuit have gradually become the main factors restricting the further improvement of the speed of the integrated circuit. Cu is widely used in metal interconnection due to its excellent performance and low price, but the diffusion speed of Cu in Si and its oxide layer is quite fast, so it is necessary to add a barrier layer between Cu and Si. SiCN has a low dielectric constant and good high temperature resistance. In the traditional scheme, trimethylsilane and ammonia are mainly used to prepare the SiCN barrier layer. However, due to the uniformity of gas mixing and defects after annealing, the local anti-puncture property of the SiCN barrier layer is poor, and breakdown is prone to occur, resulting in reduced device reliability.

[0003] The Chinese patent with the announcement number CN102110639B discloses a method for making a diffusion barrier layer, wherein a diluent gas (nitrogen), trimethylsilane and ammonia are introduced into a reaction chamber, and a diffusion barrier layer is deposited on the copper surface and the dielectric layer surface filled in the interconnection groove by multi-frequency plasma chemical vapor deposition. However, multi-frequency plasma chemical vapor deposition requires the simultaneous regulation of plasma parameters of multiple frequencies, which increases the difficulty and complexity of process parameter regulation. At the same time, slight changes in parameters may have a significant impact on the deposition results, so more precise control and monitoring means are required. The Chinese patent with the announcement number CN102403220A discloses a SiCN diffusion barrier layer preparation process, which adopts a plasma-assisted chemical vapor deposition method, and the reaction gases are trimethylsilane, ammonia and silane to deposit and form the SiCN diffusion barrier layer, but its deposition temperature is relatively high, so the equipment requirements are higher.

[0004] In summary, providing a method for preparing a SiCN diffusion barrier layer with high quality, high performance and simple process is an urgent problem to be solved. Summary of the invention

[0005] In view of the problems in the prior art of complex preparation process and poor performance of SiCN diffusion barrier layer, the present application provides a method for preparing SiCN diffusion barrier layer.

[0006] To achieve the above purpose, the technical solution adopted by the present invention is as follows:

[0007] A method for preparing a SiCN diffusion barrier layer comprises the following steps: preparing the SiCN diffusion barrier layer by using trimethylsilane, deuterated ammonia and disilane through a plasma vapor deposition method.

[0008] Preferably, the deposition temperature is 200-400°C.

[0009] Preferably, the deposition pressure is 3-6 Torr.

[0010] Preferably, the deposition time is 0.5 to 2 hours.

[0011] Preferably, the deposition power is 100-2000w.

[0012] Preferably, the purity of the trimethylsilane, deuterated ammonia and disilane is 99.99-99.999%.

[0013] Preferably, the flow rate of trimethylsilane is 100-1000 sccm, and the flow rates of deuterated ammonia and disilane are 50-1000 sccm.

[0014] Preferably, the thickness of the SiCN diffusion barrier layer is 200 to 2000 angstroms.

[0015] Based on the above technical solutions, the present invention has the following beneficial effects:

[0016] The present application uses deuterated ammonia instead of ammonia to prepare the SiCN diffusion barrier layer: the chemical bond strength of deuterated ammonia is higher than that of ammonia, so it is more stable in a high temperature environment and is not prone to decomposition reaction. In the high temperature process of preparing the SiCN diffusion barrier layer, deuterated ammonia can maintain better chemical stability and reduce impurities produced by decomposition, thereby improving the purity and performance of the barrier layer. At the same time, the molecular weight of deuterated ammonia is larger, and the atomic weight is more than doubled than that of ammonia, which may make deuterated ammonia affect the microstructure and composition of the material during the preparation of the SiCN diffusion barrier layer, thereby showing a lower defectivity after annealing. Due to the uniqueness of deuterated ammonia in chemical and physical properties, it may provide a more effective barrier effect when preparing the SiCN diffusion barrier layer. At the same time, the introduction of disilane promotes the uniform distribution of each reaction gas in the chamber, reduces the local concentration difference, and thus makes the surface of the barrier layer smoother and flatter, effectively improving the surface flatness of the barrier layer. This improvement in uniformity and flatness has an important positive impact on subsequent thin film deposition and device performance. DETAILED DESCRIPTION

[0017] In order to further explain the technical means and effects adopted by the present invention to achieve the predetermined application purpose, a clear and complete description is given below in conjunction with the preferred embodiments.

[0018] Example 1

[0019] The present embodiment provides a method for preparing a SiCN diffusion barrier layer. Before the experiment, the deposition substrate is cleaned and placed in a deposition system, and then trimethylsilane with a purity of 99.999%, deuterated ammonia with a purity of 99.999% and disilane with a purity of 99.999% are introduced into the deposition system, wherein the flow rate of trimethylsilane is 500sccm, and the flow rates of deuterated ammonia and disilane are 500sccm. The SiCN diffusion barrier layer is prepared at a temperature of 300°C, a deposition pressure of 5Torr, a deposition power of 1000w, and a deposition time of 1h.

[0020] In the high-temperature process of preparing the SiCN diffusion barrier layer, since the chemical bond strength of deuterated ammonia is higher than that of ammonia, deuterated ammonia can maintain better chemical stability in a high-temperature environment and reduce impurities produced by decomposition, thereby improving the purity and performance of the barrier layer; at the same time, the introduction of disilane promotes the uniform distribution of the reaction gases in the chamber, reduces the local concentration difference, and thus makes the surface of the barrier layer smoother and flatter, effectively improving the surface flatness of the barrier layer.

[0021] Example 2

[0022] The present embodiment provides a method for preparing a SiCN diffusion barrier layer. Before the experiment, the deposition substrate is cleaned and placed in a deposition system, and then trimethylsilane with a purity of 99.99%, deuterated ammonia with a purity of 99.999% and disilane with a purity of 99.99% are introduced into the deposition system, wherein the flow rate of trimethylsilane is 100 sccm, and the flow rates of deuterated ammonia and disilane are 50 sccm. The SiCN diffusion barrier layer is prepared at a temperature of 350°C, a deposition pressure of 6 Torr, a deposition power of 2000w, and a deposition time of 1.5h.

[0023] In the high-temperature process of preparing the SiCN diffusion barrier layer, since the chemical bond strength of deuterated ammonia is higher than that of ammonia, deuterated ammonia can maintain better chemical stability in a high-temperature environment and reduce impurities produced by decomposition, thereby improving the purity and performance of the barrier layer; at the same time, the introduction of disilane promotes the uniform distribution of the reaction gases in the chamber, reduces the local concentration difference, and thus makes the surface of the barrier layer smoother and flatter, effectively improving the surface flatness of the barrier layer.

[0024] Example 3

[0025] The present embodiment provides a method for preparing a SiCN diffusion barrier layer. Before the experiment, the deposition substrate is cleaned and placed in a deposition system, and then trimethylsilane with a purity of 99.99%, deuterated ammonia with a purity of 99.999% and disilane with a purity of 99.999% are introduced into the deposition system, wherein the flow rate of trimethylsilane is 1000sccm, and the flow rates of deuterated ammonia and disilane are 1000sccm. The SiCN diffusion barrier layer is prepared at a temperature of 400°C, a deposition pressure of 3Torr, a deposition power of 650w, and a deposition time of 0.5h.

[0026] In the high-temperature process of preparing the SiCN diffusion barrier layer, since the chemical bond strength of deuterated ammonia is higher than that of ammonia, deuterated ammonia can maintain better chemical stability in a high-temperature environment and reduce impurities produced by decomposition, thereby improving the purity and performance of the barrier layer; at the same time, the introduction of disilane promotes the uniform distribution of the reaction gases in the chamber, reduces the local concentration difference, and thus makes the surface of the barrier layer smoother and flatter, effectively improving the surface flatness of the barrier layer.

[0027] Example 4

[0028] The present embodiment provides a method for preparing a SiCN diffusion barrier layer. Before the experiment, the deposition substrate is cleaned and placed in a deposition system, and then trimethylsilane with a purity of 99.999%, deuterated ammonia with a purity of 99.99% and disilane with a purity of 99.99% are introduced into the deposition system, wherein the flow rate of trimethylsilane is 600sccm, and the flow rates of deuterated ammonia and disilane are 600sccm. The SiCN diffusion barrier layer is prepared at a temperature of 200°C, a deposition pressure of 4Torr, a deposition power of 100W, and a deposition time of 2h.

[0029] In the high-temperature process of preparing the SiCN diffusion barrier layer, since the chemical bond strength of deuterated ammonia is higher than that of ammonia, deuterated ammonia can maintain better chemical stability in a high-temperature environment and reduce impurities produced by decomposition, thereby improving the purity and performance of the barrier layer; at the same time, the introduction of disilane promotes the uniform distribution of the reaction gases in the chamber, reduces the local concentration difference, and thus makes the surface of the barrier layer smoother and flatter, effectively improving the surface flatness of the barrier layer.

[0030] Comparative Example 1

[0031] The difference between this comparative example and Example 1 is that ammonia is used instead of deuterated ammonia.

[0032] Performance Testing

[0033] The stress, thickness and dielectric constant of the SiCN diffusion barrier layer were tested, and the results are shown in Table 1.

[0034] Table 1

[0035] sample Stress(Mpa) Thickness (Angstroms) Dielectric constant Example 1 -285 800 4.89 Example 2 -250 1500 4.92 Example 3 -294 200 4.65 Example 4 -305 2000 4.75 Comparative Example 1 -325 1100 5.25

[0036] Combining Examples 1 to 4, Comparative Example 1 and Table 1, it can be seen that the present invention adopts deuterated ammonia instead of ammonia to prepare the preparation method of SiCN diffusion barrier layer, which not only releases the residual stress of SiCN diffusion barrier layer, improves the stability and reliability of the film, but also optimizes the microstructure of the film, reduces defects and porosity. Due to the large molecular weight of deuterated ammonia, the atomic weight is more than doubled than that of ammonia, so that deuterated ammonia can affect the microstructure and composition of the material during the preparation process of SiCN diffusion barrier layer, thereby showing lower defectivity after annealing treatment; at the same time, due to the uniqueness of deuterated ammonia in chemical and physical properties, it provides a more effective barrier effect when preparing SiCN diffusion barrier layer.

[0037] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Although the present invention has been disclosed as a preferred embodiment as above, it is not used to limit the present invention. Any technical personnel in this field can make some changes or modify the technical contents disclosed above into equivalent embodiments without departing from the scope of the technical solution of the present invention. However, any brief modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention are still within the scope of the technical solution of the present invention.

Claims

1. A method for preparing a SiCN diffusion barrier layer, characterized in that: The SiCN diffusion barrier layer is prepared by plasma vapor deposition of trimethylsilane, deuterated ammonia and disilane.

2. The method for preparing a SiCN diffusion barrier layer according to claim 1, characterized in that: The deposition temperature is 200-400°C.

3. The method for preparing a SiCN diffusion barrier layer according to claim 1, characterized in that: The deposition pressure is 3-6 Torr.

4. The method for preparing a SiCN diffusion barrier layer according to claim 1, characterized in that: The deposition time is 0.5 to 2 hours.

5. The method for preparing a SiCN diffusion barrier layer according to claim 1, characterized in that: The deposition power is 100-2000w.

6. The method for preparing a SiCN diffusion barrier layer according to claim 1, characterized in that: The purity of the trimethylsilane, deuterated ammonia and disilane is 99.99-99.999%.

7. The method for preparing a SiCN diffusion barrier layer according to claim 1, characterized in that: The flow rate of trimethylsilane is 100-1000 sccm, and the flow rates of deuterated ammonia and disilane are both 50-1000 sccm.

8. The method for preparing a SiCN diffusion barrier layer according to claim 1, characterized in that: The thickness of the SiCN diffusion barrier layer is 200 to 2000 angstroms.