Method for improving electromigration resistance of copper interconnection

Abstract

The invention provides a method for improving electromigration resistance of copper interconnection, which comprises the following steps of: providing a substrate, and forming an integrated circuit device on the substrate; an interconnection structure is formed on the substrate, the interconnection structure comprises a plurality of conductive parts connected with the integrated circuit device and an interlayer dielectric layer to separate and isolate various conductive parts, and a top metal wire of the interconnection structure is a copper metal wire; transferring the substrate into a process cavity, and removing water vapor in the process cavity; introducing reducing gas into the process cavity, and reducing copper oxide on the surface of the copper metal wire into copper; introducing silicon-containing gas into the process cavity to form copper silicide on the surface of the copper metal wire; introducing silicon-containing gas and nitrogen-containing gas into the process cavity at the same time, so that new copper silicide and copper nitride are formed on the surface of the copper metal wire, and a nitride layer covering the copper silicide and the copper nitride is formed; and forming a dielectric barrier layer covering the nitride layer. According to the method, the electromigration resistance of copper interconnection can be improved; and the method has good compatibility with the existing process.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor technology, and particularly to a method for improving the electromigration resistance of copper interconnects. Background Art

[0002] The electro-migration effect refers to the phenomenon of electron migration in metal wires under the action of a large current, which may lead to an open circuit in the circuit in severe cases.

[0003] The main reason for the electro-migration effect is that the momentum brought by the electron flow causes metal atoms to detach from the metal surface and migrate. With the continuous progress of the process nodes, the interconnect line width continues to decrease, and the current density passing through the interconnects continues to increase, resulting in a more and more serious electro-migration effect.

[0004] All metal interconnects are polycrystalline structures, so metal atoms have three diffusion paths, namely: lattice diffusion, grain boundary diffusion, and surface diffusion. Among them, Ea (in electron volts) [Surface] < Ea [Grain boundary] < Ea [Lattice], and the surface and grain boundaries are the main paths for metal atom migration.

[0005] To solve the above problems, a new method for improving the electromigration resistance of copper interconnects needs to be proposed. Summary of the Invention

[0006] In view of the above-mentioned disadvantages of the prior art, the purpose of the present invention is to provide a method for improving the electromigration resistance of copper interconnects, which is used to solve the problem that with the continuous progress of the process nodes in the prior art, the interconnect line width continues to decrease, the current density passing through the interconnects continues to increase, and the electro-migration effect becomes more and more serious.

[0007] To achieve the above object and other related objects, the present invention provides a method for improving the electromigration resistance of copper interconnects, including:

[0008] Step 1: Provide a substrate on which integrated circuit devices are formed;

[0009] Form an interconnect structure on the substrate, wherein the interconnect structure includes a plurality of conductive components connected to the integrated circuit devices, and includes an interlayer dielectric layer to separate and isolate various conductive components, and the top metal wire of the interconnect structure is a copper metal wire;

[0010] Step 2: Transfer the substrate to a process chamber and remove the water vapor in the process chamber;

[0011] Step 3: introducing a reducing gas into the process chamber to reduce the copper oxide on the surface of the copper metal wire to copper;

[0012] Step 4: introducing a silicon-containing gas into the process chamber to form copper silicide on the surface of the copper metal wire;

[0013] Step 5: introducing silicon-containing gas and nitrogen-containing gas into the process chamber at the same time, so that new copper silicide and copper nitride are formed on the surface of the copper metal wire, and a nitride layer covering the copper silicide and the copper nitride is formed;

[0014] Step six: forming a dielectric barrier layer covering the nitride layer.

[0015] Preferably, the substrate in step one is a silicon substrate.

[0016] Preferably, step 2 also includes a step of annealing the substrate.

[0017] Preferably, in step 2, water vapor in the process chamber is removed by introducing He into the process chamber.

[0018] Preferably, the reducing gas in step three is NH3.

[0019] Preferably, the silicon-containing gas in step 4 is SiH4.

[0020] Preferably, in step four, the silicon-containing gas is introduced into the process chamber for 0 to 15 seconds.

[0021] Preferably, the silicon-containing gas in step five is SiH4, and the nitrogen-containing gas is N2 and NH3.

[0022] Preferably, the material of the dielectric barrier layer in step six is ​​nitrogen-doped silicon carbide.

[0023] Preferably, the temperature in the process chamber in steps 2 to 6 ranges from 300 to 400 degrees Celsius.

[0024] As described above, the method for improving the electromigration resistance of copper interconnects of the present invention has the following beneficial effects:

[0025] The method of the invention can improve the electromigration resistance (EM) performance of copper interconnection; the method is simple and easy to implement and has good compatibility with existing processes. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 Shown is a schematic diagram of the process flow of the present invention;

[0027] Figure 2 Shown is a schematic diagram of the copper metal wire of the present invention;

[0028] Figure 3 It is a schematic diagram showing the formation of copper silicide, copper nitride and nitride layer according to the present invention;

[0029] Figure 4 It is a schematic diagram of forming a dielectric barrier layer according to the present invention;

[0030] Figure 5 It is a schematic diagram showing the performance improvement of the device electromigration effect of the present invention. DETAILED DESCRIPTION

[0031] The following describes the embodiments of the present invention through specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention.

[0032] See also Figure 1 The present invention provides a method for improving the anti-electromigration performance of copper interconnection, comprising:

[0033] Step 1: providing a substrate, on which an integrated circuit device is formed;

[0034] An interconnect structure is formed on the substrate, wherein the interconnect structure includes a plurality of conductive components connected to the integrated circuit device and an interlayer dielectric layer to separate and isolate various conductive components, and the top metal line of the interconnect structure is a copper metal line 101 (such as Figure 2 As shown, other structures are not shown);

[0035] Preferably, the substrate in step one is a silicon substrate.

[0036] Preferably, for example, the interconnect structure includes a contact; a metal line; and a via. The metal line is distributed in a plurality of metal layers. For example, the metal line may include copper, an aluminum-copper alloy, other suitable conductive materials, or a combination thereof. The via may include copper, an aluminum-copper alloy, other suitable conductive materials, or a combination thereof. The contact may include tungsten, silicide, nickel, cobalt, copper, other suitable conductive materials, or a combination thereof. In some examples, the various conductive components may further include barrier layers such as tantalum and tantalum nitride, titanium and titanium nitride.

[0037] Preferably, the interlayer dielectric (ILD) layer includes a dielectric material such as silicon oxide, a low-k dielectric material, other suitable dielectric materials, or a combination thereof. In some examples, the low-k dielectric material includes fluorinated silicon glass (FSG), carbon-doped silicon oxide, xerogel, aerogel, amorphous fluorinated carbon, polyparaxylene, BCB (bisbenzocyclobutene), polyimide, and / or other suitable dielectric materials having a dielectric constant substantially less than that of thermal silicon oxide. For example, the formation of the ILD layer includes deposition and CMP. The deposition may include spin coating, CVD, other suitable deposition techniques, or a combination thereof.

[0038] Step 2: transferring the substrate into a process chamber and removing water vapor in the process chamber;

[0039] Preferably, step 2 also includes a step of annealing the substrate.

[0040] Preferably, in step 2, water vapor in the process chamber is removed by introducing He into the process chamber.

[0041] For example, high-temperature He may be introduced into the process chamber, so as to simultaneously remove water vapor in the process chamber and perform annealing using high temperature.

[0042] Step 3: introducing a reducing gas into the process chamber to reduce the copper oxide on the surface of the copper metal wire 101 to copper;

[0043] Preferably, the reducing gas in step three is NH3.

[0044] Step 4: Introduce silicon-containing gas into the process chamber to form copper silicide on the surface of the copper metal wire 101. This step can increase the thickness of the CuSix alloy on the surface of the copper metal wire 101, enhance the adhesion between Cu and the dielectric barrier layer 104, reduce surface diffusion, and improve the resistance to electromigration. The thickness of the CuSix alloy can be adjusted by controlling the flow rate and time of SiH4 introduction.

[0045] Preferably, the silicon-containing gas in step 4 is SiH4.

[0046] Preferably, in step 4, silicon-containing gas is introduced into the process chamber for 0 to 15 seconds.

[0047] See also Figure 5 The step of introducing silicon-containing gas can effectively improve the EM (electromigration effect) performance of different structures, and the EM improvement effect is greater as the time of introducing silicon-containing gas increases within 0 to 5 seconds.

[0048] Step 5: A silicon-containing gas and a nitrogen-containing gas are introduced into the process chamber at the same time to form new copper silicide and copper nitride on the surface of the copper metal wire 101, and a mixed layer 102 composed of copper silicide and copper nitride is formed on the surface of the copper metal wire 101. The silicon-containing gas and the nitrogen-containing gas can also react to form a nitride layer 103 (SiNx) covering the copper silicide and copper nitride, forming a Figure 3 The structure shown;

[0049] Preferably, the silicon-containing gas in step five is SiH4, and the nitrogen-containing gas is N2 and NH3.

[0050] Step 6: forming a dielectric barrier layer 104 covering the nitride layer 103, forming a dielectric barrier layer 104 Figure 4 The structure shown.

[0051] Preferably, the material of the dielectric barrier layer 104 in step six is ​​nitrogen-doped silicon carbide.

[0052] Preferably, the temperature in the process chamber in steps 2 to 6 ranges from 300 to 400 degrees Celsius.

[0053] It should be noted that the illustrations provided in this embodiment are only used to illustrate the basic concept of the present invention in a schematic manner. Therefore, the drawings only show components related to the present invention rather than being drawn according to the number, shape and size of components in actual implementation. In actual implementation, the type, quantity and proportion of each component may be changed arbitrarily, and the component layout may also be more complicated.

[0054] In summary, the method of the present invention can improve the electromigration resistance (EM) of copper interconnects; the method is simple and easy to implement and has good compatibility with existing processes. Therefore, the present invention effectively overcomes various shortcomings of the prior art and has high industrial utilization value.

[0055] The above embodiments are merely illustrative of the principles and effects of the present invention, and are not intended to limit the present invention. Anyone familiar with the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by a person of ordinary skill in the art without departing from the spirit and technical concept disclosed by the present invention shall still be covered by the claims of the present invention.

Claims

1. A method for improving the electromigration resistance of copper interconnects, characterized in that: At least: Step 1: providing a substrate, on which an integrated circuit device is formed; forming an interconnect structure on the substrate, wherein the interconnect structure comprises a plurality of conductive components connected to the integrated circuit device and an interlayer dielectric layer to separate and isolate the various conductive components, and a top metal line of the interconnect structure is a copper metal line; Step 2: transferring the substrate into a process chamber and removing water vapor in the process chamber; Step 3: introducing a reducing gas into the process chamber to reduce the copper oxide on the surface of the copper metal wire to copper; Step 4: introducing a silicon-containing gas into the process chamber to form copper silicide on the surface of the copper metal wire; Step 5: introducing silicon-containing gas and nitrogen-containing gas into the process chamber at the same time, so that new copper silicide and copper nitride are formed on the surface of the copper metal wire, and a nitride layer covering the copper silicide and the copper nitride is formed; Step six: forming a dielectric barrier layer covering the nitride layer.

2. The method for improving the electromigration resistance of copper interconnect according to claim 1, characterized in that: The substrate in step one is a silicon substrate.

3. The method for improving the electromigration resistance of copper interconnect according to claim 1, characterized in that: Step 2 also includes the step of annealing the substrate.

4. The method for improving the electromigration resistance of copper interconnect according to claim 1, characterized in that: In step 2, water vapor in the process chamber is removed by introducing He into the process chamber.

5. The method for improving the electromigration resistance of copper interconnect according to claim 1, characterized in that: The reducing gas in step three is NH3.

6. The method for improving the electromigration resistance of copper interconnect according to claim 1, characterized in that: The silicon-containing gas in step 4 is SiH4.

7. The method for improving the electromigration resistance of copper interconnect according to claim 6, characterized in that: In step 4, the silicon-containing gas is introduced into the process chamber for 0 to 15 seconds.

8. The method for improving the electromigration resistance of copper interconnect according to claim 1, characterized in that: The silicon-containing gas in step five is SiH4, and the nitrogen-containing gas is N2 and NH3.

9. The method for improving the electromigration resistance of copper interconnect according to claim 1, characterized in that: The material of the dielectric barrier layer in step six is ​​nitrogen-doped silicon carbide.

10. The method for improving the electromigration resistance of copper interconnect according to claim 1, characterized in that: The temperature in the process chamber in step 2 to step 6 ranges from 300 to 400 degrees Celsius.

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