Technological method applied to back-end process

Abstract

The invention discloses a process method applied to a back-end process, and the method comprises the steps: providing a substrate, forming a semiconductor device on the substrate, forming an interlayer dielectric layer on the semiconductor device, forming a copper metal connecting wire in the interlayer dielectric layer, and enabling the upper surface of the copper metal connecting wire to be exposed; forming an SRN thin film layer on the copper metal connecting wire; forming a copper nitrogen compound thin film layer between the SRN thin film layer and the copper metal connecting wire; and forming a silicon nitride thin film layer on the SRN thin film layer. In the back-end process, before the silicon nitride thin film layer is formed on the copper metal connecting wire, the SRN thin film layer is formed on the copper metal connecting wire, and then the copper nitrogen compound thin film layer is formed between the SRN thin film layer and the copper metal connecting wire so as to protect the copper metal layer and prevent the copper metal layer from being bombarded by ions to form a mound-shaped protrusion defect. Therefore, the morphology defect of the copper metal layer is improved, and the reliability and yield of device products are improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of semiconductor devices and integrated circuits, and particularly relates to a process method applied to a back-end-of-line process. BACKGROUND

[0002] In a back end of line (BEOL) process of semiconductor integrated circuit manufacturing, a metal interconnection structure is usually formed to realize the lead-out of electrodes in a device. Taking a copper (Cu) metal interconnection structure as an example, after a Cu line is formed, a large number of hillock defects are usually formed after a silicon nitride (Si3N4) film layer is formed on the Cu line. The hillocks are formed by the recrystallization of Cu or copper oxide (CuO) grains under the action of high temperature in the deposition process of the silicon nitride film, and the formed regions are often located at the grain boundaries of the Cu metal layer.

[0003] In a manufacturing process with high requirements for stress migration (SM), a CuSi x film layer is usually formed between the Cu line and the silicon nitride film layer to improve the adhesion between the Cu metal layer and the silicon nitride film layer and thus improve the SM performance. However, the introduction of the CuSi film layer will cause more serious hillock defects. SUMMARY

[0004] The present application provides a process method applied to a back-end-of-line process, which can solve the problem that a copper interconnection structure provided in the related art is prone to hillock defects after a copper nitride compound is introduced. The method comprises the following steps:

[0005] A substrate is provided, a semiconductor device is formed on the substrate, an interlayer dielectric layer is formed on the semiconductor device, a Cu line is formed in the interlayer dielectric layer, and an upper surface of the Cu line is exposed outside;

[0006] An SRN film layer is formed on the Cu line;

[0007] A copper nitride compound film layer is formed between the SRN film layer and the Cu line;

[0008] A silicon nitride film layer is formed on the SRN film layer.

[0009] In some embodiments, the step of forming the SRN film layer on the Cu line comprises the following steps:

[0010] Silane and ammonia are introduced to form the SRN film layer on the Cu line.

[0011] In some embodiments, during the process of forming the SRN thin film layer on the copper metal wire, the temperature in the reaction chamber is 300-500 degrees Celsius.

[0012] In some embodiments, during the process of forming the SRN thin film layer on the copper metal wire, the flow rate of silane is 100-300 SCCM.

[0013] In some embodiments, during the process of forming the SRN thin film layer on the copper metal wire, the flow rate of ammonia is 100-300 SCCM.

[0014] In some embodiments, the process of forming the silicon nitride thin film layer on the SRN thin film layer comprises:

[0015] introducing ammonia and not introducing silane to form a copper-nitrogen compound thin film layer between the SRN thin film layer and the copper metal wire.

[0016] In some embodiments, the thickness of the SRN thin film layer is 10-30 angstroms.

[0017] In some embodiments, the thickness of the silicon nitride thin film layer is 300-500 angstroms.

[0018] The technical solution of the present application has at least the following advantages:

[0019] By forming the SRN thin film layer on the copper metal wire before forming the silicon nitride thin film layer on the copper metal wire in the back-end-of-line process, and then forming the copper-nitrogen compound thin film layer between the SRN thin film layer and the copper metal wire to protect the copper metal layer from ion bombardment to form hill-shaped protrusion defects, the morphology defects of the copper metal layer are improved on the basis of improving the stress migration performance, and the reliability and yield of the device product are improved. BRIEF DESCRIPTION OF DRAWINGS

[0020] In order to more clearly illustrate the specific embodiments of the present application or the technical solutions in the prior art, the following will briefly introduce the drawings needed to be used in the description of the specific embodiments or the prior art. Obviously, the drawings described below are some embodiments of the present application, and those skilled in the art can also obtain other drawings according to these drawings without creative labor.

[0021] Figure 1 is a flow chart of the process method applied in the back-end-of-line process provided by an exemplary embodiment of the present application;

[0022] Figures 2 to 4 is a schematic diagram of thin film layer formation of the process method applied in the back-end-of-line process provided by an exemplary embodiment of the present application. DETAILED DESCRIPTION

[0023] The technical solutions in the present application will be described clearly and completely in combination with the drawings. Obviously, the described embodiments are only some of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative effort belong to the scope of the present application.

[0024] In the description of the present application, it should be noted that the orientation or positional relationship indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. is the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present application and simplifying the description, and does not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation of the present application. In addition, the terms "first", "second", "third" are only for the purpose of description, and cannot be understood as indicating or implying relative importance.

[0025] In the description of the present application, it should be noted that unless otherwise explicitly specified and limited, the terms "mounting", "connection", "connection" should be understood broadly, for example, it can be fixed connection, or detachable connection, or integrally connected; it can be mechanical connection, or electrical connection; it can be directly connected, or indirectly connected through an intermediate medium, or the internal communication of two elements, it can be wireless connection, or wired connection. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0026] In addition, the technical features involved in different embodiments of the present application described below can be combined with each other as long as there is no conflict.

[0027] Reference Figure 1 It shows a flowchart of a process method applied in back-end-of-line provided by an exemplary embodiment of the present application, as shown in Figure 1 The method comprises the following steps:

[0028] Step S1, providing a substrate, a semiconductor device is formed on the substrate, an interlayer dielectric layer is formed on the semiconductor device, a copper metal wire is formed in the interlayer dielectric layer, and the upper surface of the copper metal wire is exposed outside.

[0029] Step S2, forming an SRN thin film layer on the copper metal wire.

[0030] Reference Figure 2 It shows a cross-sectional schematic diagram after forming a silicon rich silicon nitride (SRN) thin film layer on the copper metal wire. It should be noted that the drawings attached to the descriptionFigures 2 to 4 Only the copper metal line and other thin film layers formed on the copper metal line are shown to illustrate the embodiments of the present application. The substrate, semiconductor devices formed on the substrate, and interlayer dielectric layers are not shown.

[0031] As shown in FIG. 2B, for example, silane (SiH4) and ammonia (NH3) can be introduced to form a SRN thin film layer 220 on the copper metal line 210 by a chemical vapor deposition (CVD) process. The SRN thin film layer 220 has a thickness of 10 angstroms (A) to 30 A. Figure 2

[0032] Optionally, during the process of forming the SRN thin film layer 220 on the copper metal line 210, the temperature in the reaction chamber is 300 degrees Celsius (°C) to 500 °C, the flow rate of the silane is 100 standard cubic centimeters per minute (SCCM) to 300 SCCM, the flow rate of the ammonia is 100 SCCM to 300 SCCM, the pressure is maintained at 4 Torr to 4.4 Torr, and the power is 60 watts (W) to 100 W. Optionally, the gases introduced also include nitrogen (N2) at a flow rate of 15,000 SCCM to 20,000 SCCM.

[0033] Step S3: Forming a copper nitride thin film layer between the SRN thin film layer and the copper metal line.

[0034] Referring to FIG. 2C, which shows a cross-sectional view after the copper nitride (CuN x ) thin film layer is formed between the SRN thin film layer and the copper metal line. Figure 3 Figure 3 As shown in FIG. 2C, for example, the CVD process can be continued in the chamber of step S2 to form the copper nitride thin film layer. In this process, the ammonia is introduced without the silane to form a copper nitride thin film layer 221 between the SRN thin film layer 220 and the copper metal line 210. The copper nitride thin film layer 221 can improve stress migration.

[0035] Optionally, during the process of forming the copper nitride thin film layer between the SRN thin film layer and the copper metal line, the temperature in the reaction chamber is 300 °C to 500 °C, the flow rate of the ammonia is 100 SCCM to 300 SCCM, the pressure is maintained at 4 Torr to 4.4 Torr, and the power is 250 W to 300 W.

[0036] Step S4: Forming a silicon nitride thin film layer on the SRN thin film layer.

[0037] Referring to FIG. 2D, which shows a cross-sectional view after the silicon nitride thin film layer is formed on the SRN thin film layer.​​​Figure 4 which shows a cross-sectional view after forming the silicon nitride film layer. As shown in the example, a CVD process is used to form a silicon nitride film layer 230 on the SRN film layer 220 in the chamber of step S2 and step S3. The thickness of the silicon nitride film layer 230 is 300-500 angstroms. Figure 4

[0038] Optionally, during the process of forming the silicon nitride film layer on the SRN film layer, silane and ammonia are introduced, and the temperature in the reaction chamber is 300-500 degrees Celsius.

[0039] In summary, in the embodiments of the present application, before forming the silicon nitride film layer on the copper metal interconnect in the back-end-of-line process, an SRN film layer is first formed on the copper metal interconnect, and then a copper nitride film layer is formed between the SRN film layer and the copper metal interconnect to protect the copper metal layer from ion bombardment and form hill-shaped protrusion defects. Thus, on the basis of improving the stress migration performance, the morphology defects of the copper metal layer are improved, and the reliability and yield of the device product are improved.

[0040] Obviously, the above embodiments are only examples for clarity, and are not intended to limit the embodiments. For those skilled in the art, other different forms of changes or variations can be made on the basis of the above description. Here, it is not necessary and impossible to enumerate all the embodiments. The obvious changes or variations derived therefrom are still within the scope of protection of the present application.​

Claims

1. A process method used in a back-end process, characterized in that: include: A substrate is provided, wherein a semiconductor device is formed on the substrate, an interlayer dielectric layer is formed on the semiconductor device, a copper metal connection is formed in the interlayer dielectric layer, and the upper surface of the copper metal connection is exposed to the outside; forming an SRN thin film layer on the copper metal wiring; forming a copper nitride compound thin film layer between the SRN thin film layer and the copper metal connection; A silicon nitride thin film layer is formed on the SRN thin film layer.

2. The method according to claim 1, characterized in that The forming of the SRN thin film layer on the copper metal wiring comprises: Monosilane and ammonia are introduced to form a SRN thin film layer on the copper metal wiring.

3. The method according to claim 2, characterized in that During the process of forming the SRN thin film layer on the copper metal wiring, the temperature in the reaction chamber is 300 degrees Celsius to 500 degrees Celsius.

4. The method according to claim 3, characterized in that During the process of forming the SRN thin film layer on the copper metal wiring, the flow rate of monosilane is 100 SCCM to 300 SCCM.

5. The method according to claim 4, characterized in that During the process of forming the SRN thin film layer on the copper metal wiring, the flow rate of the ammonia gas is 100 SCCM to 300 SCCM.

6. The method according to claim 2, characterized in that The step of forming a silicon nitride thin film layer on the SRN thin film layer comprises: Ammonia gas is introduced without introducing monosilane, and a copper nitride compound thin film layer is formed between the SRN thin film layer and the copper metal wiring.

7. The method according to any one of claims 1 to 6, characterized in that: The thickness of the SRN thin film layer is 10 angstroms to 30 angstroms.

8. The method according to claim 7, characterized in that The thickness of the silicon nitride film layer is 300 angstroms to 500 angstroms.

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