Method for improving electromigration performance in Cu interconnection structure

Abstract

The invention provides a method for improving the electromigration performance in a Cu interconnection structure, and the method comprises the steps: introducing SiH4 gas into the surface of a copper wire for pretreatment, and generating a CuSix transition layer; a SiN layer is deposited on the CuSix transition layer; and depositing an NDC dielectric layer on the SiN layer. According to the invention, the adhesiveness between Cu and the NDC dielectric layer can be greatly improved, so that the electromigration performance of the device is improved.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor technology, and in particular to a method for improving electromigration performance in a Cu interconnect structure. Background Art

[0002] As integrated circuits enter process nodes below 0.18μm, copper (Cu) interconnects and low-k dielectric layers (such as NDC) are replacing traditional aluminum / silicon dioxide structures as back-end interconnects to alleviate signal delays, crosstalk, and power dissipation caused by resistance-capacitance (RC) coupling. However, the integration of copper (Cu) interconnects and low-k dielectric layer interconnects faces the critical issue of Cu atoms / ions easily diffusing into the insulating medium under certain temperature and electric field stress conditions. SIN film is the most widely used dielectric barrier layer for copper (Cu) interconnects and low-k dielectric layer interconnects, but its high dielectric constant increases parasitic capacitance between metal lines.

[0003] Therefore, most of the dielectric barrier layers are currently turning to the development of dielectric barrier layers with smaller dielectric constants, such as NDC dielectric layers. Figure 1 As shown) directly forms an NDC dielectric layer 102 on the surface (as shown) Figure 2 Compared with SIN, Figure 3 As can be seen, NDC has weaker adhesion, resulting in slightly weaker EM (electromigration) performance than NDC. On platforms with poor electromigration performance at smaller process nodes like 40nm, optimizing NDC to improve electromigration performance is particularly important.

[0004] In order to solve the above problems, it is necessary to propose a new method to improve the electromigration performance in Cu interconnect structures. Summary of the Invention

[0005] In view of the above-mentioned shortcomings of the prior art, the object of the present invention is to provide a method for improving the electromigration performance of Cu interconnect structures, so as to solve the problem in the prior art that NDC has weaker adhesion than SIN, and therefore its EM (electromigration) performance is slightly weaker than NDC.

[0006] To achieve the above objectives and other related objectives, the present invention provides a method for improving electromigration performance in a Cu interconnect structure, comprising:

[0007] Step 1: Pre-treat the copper wire surface with SiH4 gas to generate CuSi x transition layer;

[0008] Step 2: In the CuSi x Depositing a SiN layer on the transition layer;

[0009] Step three, depositing a NDC dielectric layer on the SiN layer.

[0010] Preferably, the process parameters for the pre-treatment of the copper line surface with SiH4 gas in step one are: temperature of 300-400°C, SiH4 gas flow of 200-400sccm, pressure of 2.2-2.6Torr, and pre-treatment time of 2-10 seconds.

[0011] Preferably, the SiN layer is formed by a chemical vapor deposition process using NH3 and SiH4 as ion sources in step two.

[0012] Preferably, the process parameters for depositing the SiN layer on the CuSi x Preferably, the process parameters for depositing the SiN layer on the CuSi

[0013] Preferably, the thickness of the SiN layer in step two is 10-1000A.

[0014] Preferably, the NDC dielectric layer is formed by a chemical vapor deposition process using NH3 and tetramethylsilane as ion sources in step three.

[0015] Preferably, the temperature for depositing the NDC dielectric layer on the SiN layer in step three is 300-400°C.

[0016] Preferably, the thickness of the NDC dielectric layer in step three is 10-1000A.

[0017] As described above, the method for improving the electromigration performance in Cu interconnection structure of the present application has the following beneficial effects:

[0018] The present application can greatly improve the adhesion between Cu and the NDC dielectric layer, thereby improving the electromigration performance of the device. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1 A schematic diagram of a copper line showing the prior art;

[0020] Figure 2 A schematic diagram of forming a NDC dielectric layer on a copper line showing the prior art;

[0021] Figure 3 A schematic diagram of the performance comparison between SIN and NDC dielectric layers showing the prior art;

[0022] Figure 4 A schematic diagram of the process flow showing the present application;

[0023] Figure 5 A schematic diagram showing the copper line of the present application;

[0024] Figure 6 A schematic diagram showing the formation of CuSi x transition layer;

[0025] Figure 7 A schematic diagram showing the formation of CuSi x SiN layer on the transition layer 202;

[0026] Figure 8 A schematic diagram showing the deposition of NDC dielectric layer on the SiN layer 203 of the present application;

[0027] Figure 9 A schematic diagram showing the comparison of electromigration performance of the reference group and examples 1 to 3 of the present application. DETAILED DESCRIPTION

[0028] The present application is described in detail by specific embodiments, and those skilled in the art can easily understand other advantages and effects of the present application from the disclosure of the present specification. The present application can also be implemented or applied by other different embodiments, and various modifications or changes can be made to the details in the present specification based on different views and applications without departing from the spirit of the present application.

[0029] Referring to Figure 4 , the present application provides a method for improving the electromigration performance of Cu interconnection structure, comprising:

[0030] Step 1, pre-treatment of the surface of copper line 201 (as shown in Figure 5 ) by introducing SiH4 gas to form CuSi x transition layer 202, forming a structure as shown in Figure 6 ;

[0031] In some embodiments, the process parameters for pre-treating the copper wire 201 by passing SiH4 gas through the surface in step 1 are as follows: a temperature of 300°C to 400°C, for example, 300°C, 320°C, 340°C, 360°C, 380°C, or 400°C; a SiH4 gas flow rate of 200-400 sccm, for example, 200 sccm, 250 sccm, 300 sccm, 350 sccm, or 400 sccm; a pressure of 2.2-2.6 Torr, for example, 2.2 Torr, 2.3 Torr, 2.4 Torr, 2.5 Torr, or 2.6 Torr; and a pre-treatment time of 2-10 seconds, for example, 2 seconds, 4 seconds, 6 seconds, 8 seconds, or 10 seconds. After the temperature stabilizes, the reaction gas SiH4 is introduced. The SiH4 introduced at 300°C to 400°C reacts with Cu to form a CuSix transition layer with good adhesion.

[0032] Step 2: In CuSi x A SiN layer 203 is deposited on the transition layer 202 to form a Figure 7 The structure shown in FIG. 2 is a NDC dielectric layer 204 and a CuSi x a transition layer between transition layers 202;

[0033] In some embodiments, in step 2, the SiN layer 203 is formed by a chemical vapor deposition process using NH 3 and SiH 4 as ion sources.

[0034] In some embodiments, in step 2, the CuSi x The process parameters for depositing the SiN layer 203 on the transition layer 202 are as follows: a temperature of 300°C to 400°C, for example, 300°C, 320°C, 340°C, 360°C, 380°C, and 400°C; a SiH4 gas flow rate of 200-400sccm, for example, 200sccm, 250sccm, 300sccm, 350sccm, and 400sccm; a RF power of 100-500W, for example, 100W, 200W, 300W, 400W, and 500W; and a pressure of 2.2-2.6Torr, for example, 2.2Torr, 2.3Torr, 2.4Torr, 2.5Torr, and 2.6Torr.

[0035] In some embodiments, the thickness of the SiN layer 203 in step 2 is 10 to

[0036] Step 3: Deposit an NDC dielectric layer 204 on the SiN layer 203 to form a Figure 8 The structure shown.

[0037] In some embodiments, in step three, the NDC dielectric layer 204 is formed by a chemical vapor deposition process using NH 3 and tetramethylsilane as ion sources.

[0038] In some embodiments, the temperature for depositing the NDC dielectric layer 204 on the SiN layer 203 in step three is 300-400℃.

[0039] In some embodiments, the thickness of the NDC dielectric layer 204 in step three is 10-50nm.

[0040] Referring to Figure 9 , which shows the electromigration performance comparison of the reference group and the embodiments one to three of the present application. By increasing the SIN deposition time and adjusting the SiH4 infiltration time 0s, 3s, 5s, the failure time T0.1% (yrs) is increased from 1.20E+02 to 4.83E+02.

[0041] It should be noted that the diagrams provided in the embodiments only schematically illustrate the basic concept of the present application, and only the components related to the present application are shown in the diagrams, not the number, shape and size of the components when actually implemented. The actual implementation of each component can be randomly changed in shape, number and proportion, and the layout pattern of the components can be more complex.

[0042] In summary, the present application can greatly improve the adhesion between Cu and the NDC dielectric layer, thereby improving the electromigration performance of the device. Therefore, the present application effectively overcomes the various shortcomings in the prior art and has a high industrial utilization value.

[0043] The above embodiments only illustratively explain the principles and effects of the present application, and are not used to limit the present application. Any person skilled in the art can modify or change the above embodiments without departing from the spirit and scope of the present application. Therefore, all equivalent modifications or changes made by those skilled in the art without departing from the spirit and technical idea of the present application should be covered by the claims of the present application.

Claims

1. A method for improving electromigration performance in a Cu interconnect structure, characterized in that: At least: Step 1: Pre-treat the copper wire surface with SiH4 gas to generate CuSi x transition layer; Step 2: In the CuSi x Depositing a SiN layer on the transition layer; Step 3: depositing an NDC dielectric layer on the SiN layer.

2. The method for improving electromigration performance in a Cu interconnect structure according to claim 1, wherein: The process parameters for pre-treatment of the copper wire surface by introducing SiH4 gas in step 1 are: temperature of 300°C to 400°C, SiH4 gas flow rate of 200-400 sccm, pressure of 2.2-2.6 Torr, and pre-treatment time of 2-10 seconds.

3. The method for improving electromigration performance in a Cu interconnect structure according to claim 1, wherein: In step 2, the SiN layer is formed by a chemical vapor deposition process using NH 3 and SiH 4 as ion sources.

4. The method for improving electromigration performance in a Cu interconnect structure according to claim 3, wherein: In step 2, the CuSi x The process parameters for depositing the SiN layer on the transition layer are: temperature of 300°C to 400°C, SiH4 gas flow rate of 200-400sccm, RF power of 100-500W, and pressure of 2.2-2.6Torr.

5. The method for improving electromigration performance in a Cu interconnect structure according to claim 1, wherein: The thickness of the SiN layer in step 2 is 10 to 6. The method for improving electromigration performance in a Cu interconnect structure according to claim 1, wherein: In step three, the NDC dielectric layer is formed by a chemical vapor deposition process using NH 3 and tetramethylsilane as ion sources.

7. The method for improving electromigration performance in a Cu interconnect structure according to claim 6, wherein: In step 3, the temperature for depositing the NDC dielectric layer on the SiN layer is 300° C. to 400° C.

8. The method for improving electromigration performance in a Cu interconnect structure according to claim 1, wherein: The thickness of the NDC dielectric layer in step 3 is 10 to

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