Measurement method of anti-sputtering rate

Abstract

The present invention provides a method for measuring the anti-sputtering rate. A first thin film layer is formed on a wafer through a sputtering process and an anti-sputtering process. Then, a gas is introduced into the reaction chamber to form a dense first protective layer on the first thin film layer; an insulating layer is formed on the first protective layer; on the insulating layer, a second thin film layer is formed through a sputtering process. The first thin film layer and the second thin film layer are made of the same material. Then, a gas is introduced into the reaction chamber to form a dense second protective layer on the second thin film layer; the anti-sputtering rate is calculated based on the first and second resistances of the first and second thin film layers, the resistivity of the first and second thin film layers, and the time for forming the first thin film layer. By introducing a gas after film deposition to form a protective layer, the surface activity of the deposited film is reduced, interference factors such as surface oxidation and the time for two film depositions are decreased, and the detection stability of the anti-sputtering rate in the PVD tantalum chamber is optimized.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor technology, and particularly to a method for measuring the reverse sputtering rate. Background Art

[0002] The working principle of a PVD (Physical Vapor Deposition) tantalum chamber is to use Ar ions in the plasma to bombard the object to be sputtered (such as a tantalum target), so that tantalum particles are present in the gas-phase plasma. These tantalum particles are deposited on the silicon wafer to form a tantalum thin film (as Figure 1 shown).

[0003] The reverse sputtering process is to directly bombard the tantalum thin film with tantalum particles to etch the thin film (as Figure 2 shown).

[0004] The reverse sputtering rate is a parameter reflecting the etching rate in the reverse sputtering process. In related technologies, the method for measuring the reverse sputtering rate is as follows: A thin film with a thickness of H1 is formed on the wafer through the sputtering process and the reverse sputtering process. A thin film with a thickness of H2 is deposited on the wafer 2 through the sputtering process. The thickness of the etched thin film is calculated, that is, (H2 - H1), and then divided by the reverse sputtering time to obtain the reverse sputtering rate.

[0005] The existing method for detecting and calculating the reverse sputtering rate of a tantalum thin film: Different tantalum thin films are grown on the same wafer in two times, and the thickness difference of the thin films is detected by measuring the resistance value (as Figure 3 shown).

[0006] However, please refer to Figure 4 , due to factors such as the idle time of the chamber for the two thin films, the interval time for the growth of the two thin films, and the oxidation of the thin film stored in the FOUP, the thickness values fluctuate, and the stability of the calculated thickness difference of the thin films is poor (as Figure 4 shown), and the actual reverse sputtering rate of the chamber cannot be effectively detected.

[0007] To solve the above problems, a new method for measuring the reverse sputtering rate needs to be proposed. Summary of the Invention

[0008] In view of the above-mentioned disadvantages of the prior art, the purpose of the present invention is to provide a method for measuring the reverse sputtering rate, which is used to solve the problem in the prior art that due to factors such as the idle time of the chamber for the two thin films, the interval time for the growth of the two thin films, and the oxidation of the thin film stored in the FOUP, the thickness values fluctuate, the stability of the calculated thickness difference of the thin films is poor, and the actual reverse sputtering rate of the chamber cannot be effectively detected.

[0009] To achieve the above purpose and other related purposes, the present invention provides a method for measuring the reverse sputtering rate, including:

[0010] A first thin film layer is formed on the wafer through a sputtering process and an anti-sputtering process. Then, a gas is introduced into the reaction chamber to form a dense first protective layer on the first thin film layer;

[0011] An insulating layer is formed on the first protective layer;

[0012] On the insulating layer, a second thin film layer is formed through the sputtering process. The first thin film layer and the second thin film layer are made of the same material. Then, the gas is introduced into the reaction chamber to form a dense second protective layer on the second thin film layer;

[0013] The anti-sputtering rate is calculated through the first and second resistances of the first and second thin film layers, the resistivity of the first and second thin film layers, and the time for forming the first thin film layer.

[0014] Preferably, both the first thin film layer and the second thin film layer are metal thin film layers.

[0015] Preferably, the metal thin film layer is a tantalum thin film layer.

[0016] Preferably, the method for forming the first thin film layer through the sputtering process and the anti-sputtering process includes: bombarding a tantalum target with argon ions to form a first tantalum layer on the wafer, and bombarding the first tantalum layer with tantalum ions to etch the first tantalum layer to form the first thin film layer.

[0017] Preferably, the method for forming the second thin film layer through the sputtering process includes: bombarding the tantalum target with argon ions to form the second thin film layer on the insulating layer.

[0018] Preferably, the gas is nitrogen, and the nitrogen is used to form titanium nitride thin films on the first and second thin film layers.

[0019] Preferably, the calculation of the anti-sputtering rate through the first and second resistances of the first and second thin film layers, the resistivity of the first and second thin film layers, and the time for forming the first thin film layer includes: calculating the anti-sputtering rate through the first and second resistances of the first and second thin film layers, the resistivity of the first and second thin film layers, and the time for forming the first thin film layer according to the following formula:

[0020] Anti-sputtering rate = difference in anti-sputtering etched film thickness / anti-sputtering time, i.e., (ρTa / Rsdeponly - ρTa / Rsdepetch) / t = (ρTa / Rsdeponly2 - 2ρTa / Rsdepetch) / t, where ρTa is the resistivity of the tantalum thin film, t is the anti-sputtering time, Rsdeponly is the resistance value of the second thin film layer, Rsdepetch is the resistance value of the first thin film layer, and Rsdeponly2 is the sum of the thicknesses of the first and second thin film layers.

[0021] Preferably, after forming a dense first protective layer on the first thin film layer, it further includes: measuring the resistance value of the first thin film layer.

[0022] Preferably, after forming a dense second protective layer on the second thin film layer, it further includes: measuring the resistance value of the second thin film layer.

[0023] As described above, the method for measuring the anti-sputtering rate of the present invention has the following beneficial effects:

[0024] By introducing a gas after thin film deposition to form a protective layer, the surface activity of the deposited thin film is reduced, surface oxidation is reduced, and interference factors such as the time of two thin film depositions are reduced, optimizing the detection stability of the anti-sputtering rate of the PVD tantalum cavity. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 Schematic diagram of a sputtering process shown as the prior art;

[0026] Figure 2 Schematic diagram of an anti-sputtering process shown as the prior art;

[0027] Figure 3 Schematic diagram of an anti-sputtering rate detection shown as the prior art;

[0028] Figure 4 Schematic diagram of an anti-sputtering rate trend shown as the prior art;

[0029] Figure 5 Schematic diagram of the anti-sputtering rate test method of the present invention;

[0030] Figure 6 Schematic diagram of the test structure of the present invention;

[0031] Figure 7 Schematic diagram of an anti-sputtering rate trend of the present invention;

[0032] Figure 8 Schematic diagram of the comparison of the anti-sputtering rate results of the present invention with the prior art. DETAILED DESCRIPTION OF THE INVENTION

[0033] The following describes the embodiments of the present invention through specific examples. Those skilled in the art can easily understand the other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments. Various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention.

[0034] Please refer to Figure 5 , the present invention provides a method for measuring the anti-sputtering rate, including:

[0035] Step 1: Form a first thin film layer 01 on the wafer through a sputtering process and an anti-sputtering process. Then, introduce a gas into the reaction chamber to form a dense first protective layer 04 on the first thin film layer 01.

[0036] In the embodiment of the present invention, the first thin film layer 01 is a metal thin film layer.

[0037] In the embodiment of the present invention, the metal thin film layer is a tantalum thin film layer, that is, the first thin film layer 01 is a tantalum thin film layer.

[0038] In the embodiment of the present invention, the method for forming the first thin film layer 01 through a sputtering process and an anti-sputtering process includes: bombarding a tantalum target with argon ions to form a first tantalum layer on the wafer, and using tantalum ions to bombard the first tantalum layer to etch the first tantalum layer to form the first thin film layer 01.

[0039] In the embodiment of the present invention, the gas is nitrogen, and nitrogen is used to form a titanium nitride thin film on the first thin film layer 01.

[0040] In the embodiment of the present invention, after forming a dense first protective layer 04 on the first thin film layer 01, it further includes: measuring the resistance value of the first thin film layer 01.

[0041] Step 2: Form an insulating layer 02 on the first protective layer 04. When measuring the first and second thin films, the first and second thin film layers can be regarded as two resistors in series;

[0042] In the embodiment of the present invention, the material of the insulating layer 02 is silicon dioxide. It should be noted that the insulating layer 02 can also be other insulating materials known to those skilled in the art.

[0043] Step 3: On the insulating layer 02, form a second thin film layer 03 through a sputtering process. The first thin film layer 01 and the second thin film layer 03 are made of the same material. Then, introduce a gas into the reaction chamber to form a dense second protective layer 05 on the second thin film layer 03, obtaining the structure as Figure 6 shown;

[0044] In the embodiment of the present invention, the second thin film layer 03 is a metal thin film layer.

[0045] In an embodiment of the present invention, the metal thin film layer is a tantalum thin film layer, that is, the second thin film layer 03 is a tantalum thin film layer.

[0046] In an embodiment of the present invention, the method for forming the second thin film layer 03 by a sputtering process includes: bombarding a tantalum target with argon ions to form the second thin film layer 03 on the insulating layer 02.

[0047] In an embodiment of the present invention, the gas is nitrogen, and the nitrogen is used to form a titanium nitride thin film on the second thin film layer 03.

[0048] In an embodiment of the present invention, after forming a dense second protective layer 05 on the second thin film layer 03, it further includes: measuring the resistance value of the second thin film layer 03.

[0049] Step Four: Calculate the backsputtering rate through the first and second resistances of the first and second thin film layers, the resistivity of the first and second thin film layers, and the time for forming the first thin film layer 01. Since the first and second protective layers are respectively formed on the first and second thin films, the surface activity of the deposited thin film is reduced, interference factors such as surface oxidation and the time for two thin film depositions are reduced, and the detection stability of the backsputtering rate of the PVD tantalum cavity is optimized.

[0050] In an embodiment of the present invention, calculating the backsputtering rate through the first and second resistances of the first and second thin film layers, the resistivity of the first and second thin film layers, and the time for forming the first thin film layer 01 includes: calculating the backsputtering rate through the first and second resistances of the first and second thin film layers, the resistivity of the first and second thin film layers, and the time for forming the first thin film layer 01, and calculating the backsputtering rate through the following formula:

[0051] Backsputtering rate = backsputtering etching film thickness difference / backsputtering time, that is, (ρTa / Rsdeponly - ρTa / Rsdepetch) / t = (ρTa / Rsdeponly2 - 2ρTa / Rsdepetch) / t, where ρTa is the resistivity of the tantalum thin film, t is the backsputtering time, Rsdeponly is the resistance value of the second thin film layer 03, Rsdepetch is the resistance value of the first thin film layer 01, and Rsdeponly2 is the sum of the thicknesses of the first and second thin film layers.

[0052] That is, the resistances of these two thin films can be regarded as series resistances.

[0053] Therefore, the total thin film thickness: ρTa / Rsdeponly2 = ρTa / Rsdepetch + ρTa / Rsdeponly Formula (2)

[0054] The formula (2) is derived to obtain ρTa / Rsdeponly = ρTa / Rsdeponly2 - ρTa / Rsdepetch, formula (3).

[0055] Substituting formula (3) into formula (1) gives the optimized anti-sputtering rate calculation formula:

[0056] Anti-sputtering etching rate = anti-sputtering etching film thickness difference / anti-sputtering time

[0057] =(ρTa / Rsdeponly - ρTa / Rsdepetch) / t = (ρTa / Rsdeponly2 - 2ρTa / Rsdepetch) / t.

[0058] In an embodiment of the present invention, please refer to Figure 7 and Figure 8 , which are respectively the anti-sputtering rate trend chart and the analysis structure obtained by the anti-sputtering rate measurement method of the present invention. The measured data is very stable, and the difference from the prior art calculation is smaller.

[0059] It should be noted that the illustrations provided in this embodiment only illustrate the basic concept of the present invention in a schematic manner. Therefore, only the components related to the present invention are shown in the drawings, rather than being drawn according to the number, shape, and size of the components in actual implementation. The types, quantities, and proportions of the components in actual implementation can be arbitrarily changed, and the component layout type may also be more complex.

[0060] In summary, the present invention forms a protective layer by introducing gas after film deposition, reducing the surface activity of the deposited film, reducing surface oxidation, and reducing interference factors such as the time of two film depositions, optimizing the detection stability of the anti-sputtering rate of the PVD tantalum cavity. Therefore, the present invention effectively overcomes various disadvantages in the prior art and has high industrial utilization value.

[0061] The above embodiments are only illustrative of the principles and effects of the present invention, and are not used to limit the present invention. Any person familiar with this technology can modify or change the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or changes completed by those with ordinary knowledge in the technical field without departing from the spirit and technical idea disclosed by the present invention should still be covered by the claims of the present invention.

Claims

1. A method for measuring the anti-sputtering rate, characterized in that Comprising: A first thin film layer is formed on a wafer through a sputtering process and a reverse sputtering process. Then, a gas is introduced into a reaction chamber to form a dense first protective layer on the first thin film layer; An insulating layer is formed on the first protective layer; On the insulating layer, a second thin film layer is formed through the sputtering process. The first thin film layer and the second thin film layer are made of the same material. Then, the gas is introduced into the reaction chamber to form a dense second protective layer on the second thin film layer; The reverse sputtering rate is calculated through the first and second resistances of the first and second thin film layers, the resistivity of the first and second thin film layers, and the time for forming the first thin film layer.

2. The method for measuring the backsputtering rate according to claim 1, characterized in that: Both the first thin film layer and the second thin film layer are metal thin film layers.

3. The method for measuring the anti-sputtering rate according to claim 2, wherein: The metal thin film layer is a tantalum thin film layer.

4. The method for measuring the backsputtering rate according to claim 3, characterized in that: The method for forming the first thin film layer through the sputtering process and the reverse sputtering process includes: bombarding a tantalum target with argon ions to form a first tantalum layer on the wafer, and bombarding the first tantalum layer with tantalum ions to etch the first tantalum layer to form the first thin film layer.

5. The method for measuring the anti-sputtering rate according to claim 4, characterized in that: The method for forming the second thin film layer through the sputtering process includes: bombarding the tantalum target with argon ions to form the second thin film layer on the insulating layer.

6. The method for measuring the anti-sputtering rate according to claim 1, wherein: The material of the insulating layer is silicon dioxide.

7. The method for measuring the anti-sputtering rate according to claim 5, characterized in that: The gas is nitrogen, and the nitrogen is used to form titanium nitride thin films on the first and second thin film layers.

8. The method for measuring the anti-sputtering rate according to claim 1, characterized in that: The calculating the reverse sputtering rate through the first and second resistances of the first and second thin film layers, the resistivity of the first and second thin film layers, and the time for forming the first thin film layer includes: calculating the reverse sputtering rate through the first and second resistances of the first and second thin film layers, the resistivity of the first and second thin film layers, and the time for forming the first thin film layer according to the following formula: Reverse sputtering rate = reverse sputtering etching film thickness difference / reverse sputtering time, that is, (ρTa / Rsdeponly - ρTa / Rsdepetch) / t = (ρTa / Rsdeponly2 - 2ρTa / Rsdepetch) / t, where ρTa is the resistivity of the tantalum thin film, t is the reverse sputtering time, Rsdeponly is the resistance value of the second thin film layer, Rsdepetch is the resistance value of the first thin film layer, and Rsdeponly2 is the sum of the thicknesses of the first and second thin film layers.

9. The method for measuring the backsputtering rate according to claim 8, characterized in that: After forming the dense first protective layer on the first thin film layer, it further includes: measuring the resistance value of the first thin film layer.

10. The method for measuring the anti-sputtering rate according to claim 9, wherein: After forming the dense second protective layer on the second thin film layer, it further includes: measuring the resistance value of the second thin film layer.

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