Manufacturing method of metal electrode and NMOS (N-channel Metal Oxide Semiconductor) device

Abstract

The invention provides a manufacturing method of a metal electrode and an NMOS device, and belongs to the field of semiconductors. The manufacturing method of the metal electrode comprises the following steps: providing a semiconductor structure, wherein the semiconductor structure is provided with a gate structure layer; and depositing a work function metal layer on the surface of the gate structure layer. And depositing a first barrier layer on the surface of the work function metal layer in a vapor deposition mode, wherein the vapor deposition temperature is 25-340 DEG C. And depositing a metal layer on the surface of the first barrier layer as a contact electrode. When the TiN layer is deposited, chemical vapor deposition or physical vapor deposition is adopted to replace a traditional atomic layer deposition mode, the deposition temperature is reduced, diffusion of the TiAL layer to the TiN layer can be reduced, diffusion of AL in the TiAL layer to the metal layer can be prevented, it can be ensured that the performance of an NMOS device reaches the expectation, and meanwhile the performance of the NMOS device is improved. And the yield of the NMOS device can be improved.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor technology, and in particular to a method for manufacturing a metal electrode and an NMOS device. Background Art

[0002] NMOS means N-type metal-oxide-semiconductor, and transistors with this structure are called NMOS transistors. Since metal tungsten (W) is a high-melting-point, high-density metal that can provide better thermal stability and mechanical strength in practical applications, in order to improve the performance and reliability of NMOS devices, tungsten may be selected as the gate material to replace aluminum at the 22-nanometer process node. The tensile stress of W-gate can improve the performance of NMOS and reduce the metal gate resistance by 50%.

[0003] However, after replacing aluminum with tungsten as the gate material, it was found that although the electrical parameters of the NMOS device met expectations, the yield was reduced, and the wafer scanning image obtained by the electron scanning microscope showed that the Al in the TiAl deposited in the gate structure layer diffused upward into the metal W. It was found that the diffusion of metal Al caused the NMOS device yield to decrease.

[0004] It should be noted that the information disclosed in the background technology section of the invention is only intended to deepen the understanding of the general background technology of the invention, and should not be regarded as an admission or suggestion in any form that the information constitutes prior art already known to those skilled in the art. Summary of the invention

[0005] The object of the present invention is to provide a method for manufacturing a metal electrode and an NMOS device, so as to solve the problem of decreased yield of the NMOS device caused by diffusion of metal Al into metal W.

[0006] In order to solve the above technical problems, the present invention provides a method for manufacturing a metal electrode, comprising:

[0007] Providing a semiconductor structure, the semiconductor structure having a gate structure layer;

[0008] Depositing a work function metal layer on the surface of the gate structure layer;

[0009] Depositing a first barrier layer on the surface of the work function metal layer by vapor deposition, wherein the vapor deposition temperature is 25° C. to 340° C.;

[0010] A metal layer is deposited on the surface of the first barrier layer as a contact electrode.

[0011] Preferably, before depositing the first barrier layer, the method for manufacturing the metal electrode further comprises:

[0012] A second barrier layer is deposited on the surface of the work function metal layer.

[0013] Preferably, depositing a first barrier layer on the surface of the work function metal layer by vapor deposition comprises:

[0014] A first barrier layer is deposited on the surface of the work function metal layer by chemical vapor deposition, and the temperature of the chemical vapor deposition is 340°C.

[0015] Preferably, depositing a first barrier layer on the surface of the work function metal layer by vapor deposition comprises:

[0016] A first barrier layer is deposited on the surface of the work function metal layer by physical vapor deposition, and the temperature of the physical vapor deposition is 25°C.

[0017] Preferably, depositing a second barrier layer on the surface of the work function metal layer comprises:

[0018] A second barrier layer is deposited on the surface of the work function metal layer by vapor deposition, and the vapor deposition temperature is 275°C.

[0019] Preferably, the material of the work function metal layer is TiAL alloy.

[0020] Preferably, the material used for the first barrier layer is TiN.

[0021] Preferably, the material of the second barrier layer is TaN, and the thickness of the second barrier layer is 1.5 nanometers.

[0022] Preferably, the material of the metal layer deposited on the surface of the first barrier layer is metal tungsten.

[0023] Based on the same inventive concept, the present invention also provides an NMOS device, comprising:

[0024] The metal electrode is manufactured by adopting the above-mentioned method for manufacturing the metal electrode.

[0025] Compared with the prior art, the method for making the metal electrode of the present invention has the following advantages:

[0026] The method for manufacturing the metal electrode provided by the present invention reduces the deposition temperature by adopting chemical vapor deposition or physical vapor deposition instead of the traditional atomic layer deposition deposition method when depositing the TiN layer, thereby reducing the diffusion of the TiAL layer into the TiN layer, and further preventing the Al in the TiAL layer from diffusing into the metal layer, thereby ensuring that the performance of the NMOS device reaches the expected level while also improving the yield of the NMOS device.

[0027] In addition, by providing the TaN layer, the TiAL layer can be further blocked, thereby further preventing the TiAL layer from diffusing into the TiN layer, and further preventing the Al in the TiAL layer from further diffusing into the metal layer, thereby further improving the yield of the NMOS device.

[0028] The NMOS device provided by the present invention and the method for manufacturing the metal electrode provided by the present invention belong to the same inventive concept. Therefore, the NMOS device provided by the present invention has at least all the advantages of the method for manufacturing the metal electrode provided by the present invention, and can ensure that the performance of the NMOS device reaches the expected level while also improving the yield of the NMOS device. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is a flow chart of a method for making a metal electrode of the present invention;

[0030] Figure 2 is a schematic diagram of yield distribution of wafer inspection in one embodiment;

[0031] Figure 3 is a schematic diagram of electrical performance parameters of an NMOS device in one embodiment of the present invention;

[0032] Figure 4 is an electronically scanned image in one embodiment of the present invention;

[0033] Figure 5 is a schematic diagram of the structure of metal electrode deposition in one embodiment of the present invention;

[0034] Figure 6 is a schematic diagram of the yield of an NMOS device obtained by depositing different titanium nitride layer thicknesses in one embodiment of the present invention;

[0035] Figure 7 This is a schematic diagram of the yield distribution of a wafer obtained by using the method for manufacturing a metal electrode provided by the present invention in one embodiment;

[0036] Figure 8 is a schematic diagram of wafer yield distribution obtained under different conditions in one embodiment of the present invention;

[0037] In the figure,

[0038] 100-TiAL layer; 200-TaN layer;

[0039] 300-TiN layer; 400-metal layer. DETAILED DESCRIPTION

[0040] In order to make the purpose, advantages and features of the present invention clearer, the following is a further detailed description of the method for making the metal electrode and the NMOS device proposed in the present invention in combination with the drawings and specific embodiments. It should be noted that the drawings are all in a very simplified form and are not in precise proportions, which are only used to conveniently and clearly assist in explaining the purpose of the embodiments of the present invention. It should be understood that the drawings in the specification do not necessarily show the specific structure of the present invention in proportion, and the illustrative features used to illustrate certain principles of the present invention in the drawings in the specification will also adopt a slightly simplified drawing method. The specific design features of the present invention disclosed herein include, for example, specific dimensions, directions, positions and shapes, which will be determined in part by the specific application and use environment. And, in the embodiments described below, sometimes the same figure mark is used in common between different drawings to represent the same part or a part with the same function, and its repeated description is omitted. In this specification, similar numbers and letters are used to represent similar items, so once an item is defined in one drawing, it does not need to be further discussed in subsequent drawings.

[0041] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of the present invention, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0042] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0043] Ginseng Figures 2 to 4 As shown, in the prior art, in order to improve the performance and reliability of NMOS devices, metal tungsten is used as the gate material to replace metal aluminum. Figure 3 It can be seen that when metal tungsten is used as the gate material to replace metal aluminum, the performance of the NMOS device, such as Figure 3 The relationship between the saturation current shown on the horizontal axis and the leakage current shown on the vertical axis shows that the electrical parameters of the MOS device have reached the expected level. Figure 4 The wafer scan image shown shows that Figure 4 In the metal W layer, there is metal Al at a. Further, by testing the wafer, we can get the following Figure 2 The test results are shown. Figure 2 In the figure, the color shown in d represents a good device, and the color shown in c represents a defective device. Figure 2 It can be found that the yield of NMOS devices decreases. Therefore, due to the diffusion of metal Al into metal W, the yield of the device decreases.

[0044] The core idea of ​​the present invention is to provide a method for manufacturing a metal electrode, which can solve the problem of reduced yield of NMOS devices caused by diffusion of metal Al into metal W.

[0045] In order to realize the above idea, the present invention provides a method for manufacturing a metal electrode. Figures 1 to 8 A specific implementation of a method for manufacturing a metal electrode disclosed herein includes the following steps S1 to S4.

[0046] Step S1: providing a semiconductor structure having a gate structure layer.

[0047] Step S2: depositing a work function metal layer on the surface of the gate structure layer.

[0048] Specifically, refer to Figure 1 and Figure 4 As shown, a work function metal layer is deposited on the surface of the gate structure layer. The material of the work function metal layer is TiAL alloy. It is used to adjust the electrical parameters of the NMOS device, such as saturation current, leakage current, etc. In this embodiment, preferably, the material used for the work function metal layer is TiAL alloy. Therefore, the work function metal layer can also be called a TiAL layer. The thickness of the TiAL layer can be set based on design requirements. When depositing the TiAL layer, it can be deposited by chemical vapor deposition (CVD), physical vapor deposition (PVD), or atomic layer deposition (ALD), and there is no specific requirement for the deposition temperature.

[0049] Step S3: depositing a first barrier layer on the surface of the work function metal layer by vapor deposition, wherein the vapor deposition temperature is 25° C. to 340° C.

[0050] Specifically, refer to Figure 1 and Figure 5As shown, a first barrier layer is deposited on the surface of the TiAL layer by vapor deposition. The material of the first barrier layer is titanium nitride (TiN). The first barrier layer can be referred to as a TiN layer 300. Depositing the TiN layer 300 on the surface of the TiAL layer 100 by vapor deposition includes: depositing the TiAL100 layer on the surface of the TiAL layer 100 by chemical vapor deposition (CVD), and the temperature of the chemical vapor deposition is preferably 340°C. Low-temperature chemical vapor deposition (LT-CVD) is preferred for chemical vapor deposition (CVD). Since the commonly used temperature of low-temperature chemical vapor deposition (LT-CVD) can be as low as 200°C, the temperature of the chemical vapor deposition can be 200 to 340°C.

[0051] Depositing the TiN layer 300 on the surface of the TiAL100 layer by vapor deposition includes: depositing the TiAL100 layer on the surface of the TiAL100 layer by physical vapor deposition (PVD), wherein the temperature of the physical vapor deposition is 25° C. to 200° C. The TiN layer 300 can provide a structural layer for growing metal tungsten in a subsequent process. In addition, in a subsequent process, a fluorine-containing gas is used for the process, and the deposited TiN layer 300 can also play a role in blocking the diffusion of fluorine.

[0052] In the conventional method of depositing the TiN layer 300, an atomic layer deposition (ALD) deposition method is adopted, and the temperature of depositing the TiN layer 300 is above 450° C. As the thickness increases and the time spent in the deposition chamber increases, the TiAL layer 100 diffuses more seriously into the TiN layer 300, thereby reducing the yield of the NMOS device.

[0053] However, in this embodiment, when depositing the TiN layer 300, the deposition temperature is lowered by adopting chemical vapor deposition (CVD) or physical vapor deposition (PVD) instead of the traditional atomic layer deposition (ALD) deposition method, thereby reducing the diffusion of the TiAL layer 100 into the TiN layer 300, and further preventing the Al in the TiAL layer 100 from diffusing into the metal layer, thereby ensuring that the performance of the NMOS device reaches the expected level while also improving the yield of the NMOS device.

[0054] Furthermore, in order to further diffuse the metal Al into the metal W layer, before depositing the TiN layer 300, a second barrier layer is first deposited on the surface of the TiAl layer 100, and then the first barrier layer is deposited on the surface of the second barrier layer. The material of the second barrier layer is tantalum nitride (TaN). The second barrier layer can be called a TaN layer. Figure 1 and Figure 5As shown, first, a TaN layer 200 is deposited on the surface of the TiAL layer 100. Then, a TiN layer 300 is deposited on the surface of the TaN layer 200. When depositing the TaN layer 200, the TaN layer 200 is deposited by vapor deposition, such as chemical vapor deposition. The temperature of the TaN layer 200 during deposition is preferably 275°C. The thickness of the deposited TaN layer is preferably 1.5 nanometers. By providing the TaN layer 200, the TiAL layer 100 can be further blocked, thereby further preventing the TiAL layer 100 from diffusing into the TiN layer 300, and further preventing the Al in the TiAL layer 100 from further diffusing into the metal layer, thereby further improving the yield of the NMOS device.

[0055] Step S4: depositing a metal layer 400 on the surface of the first barrier layer as a contact electrode.

[0056] Specifically, refer to Figure 1 and Figure 5 As shown, metal tungsten is deposited on the surface of the TiN layer 300 as a contact electrode.

[0057] The above-mentioned method for making metal electrodes is used to make metal tungsten, and the metal tungsten is used as the contact electrode. The yield of the NMOS device obtained is as follows: Figure 7 As shown, Figure 7 The color displayed at position d is a good product, and the color displayed at position c is a defective product. Figure 2 and Figure 7 Compared with the yield in Figure 7 The yield of NMOS devices is significantly higher than Figure 2 The yield of NMOS devices in the test.

[0058] Ginseng Figures 6 to 8 As shown, under the condition that the TiN layer 300 is deposited by atomic layer deposition (ALD), the thickness of the TiN layer 300 is changed, and the yield of the device is measured, and the following is obtained: Figure 6 The schematic diagram shown. Figure 6 It can be seen that the thickness of the TiN layer 300 deposited has no effect on the yield of the device. Therefore, the influence of the thickness of the TiN layer 300 deposited on the yield of the device can be ruled out. Figure 6 It can be seen that when the TiN layer 300 is deposited by atomic layer deposition (ALD), the yield of the NMOS device is low.

[0059] Ginseng Figure 8 As shown, the yield of the device is measured under four conditions, and the yield distribution diagram of the wafer test results is obtained as shown in Figure 8As shown. The first condition is: using atomic layer deposition (ALD) to deposit the TiN layer 300. The second condition is: using chemical vapor deposition (CVD) to deposit the TiN layer 300. The third condition is: depositing a TaN layer 200 between the TiAL layer 100 and the TiN layer 300. At the same time, using atomic layer deposition (ALD) to deposit the TiN layer 300. The fourth condition is: depositing a TaN layer 200 between the TiAL layer 100 and the TiN layer 300. At the same time, using chemical vapor deposition (CVD) to deposit the TiN layer 300. As can be seen from the figure, under the fourth condition, the device yield is the highest, reaching more than 90%.

[0060] To realize the above idea, this embodiment further discloses an NMOS device, including: a metal electrode is manufactured by using the above-mentioned method for manufacturing a metal electrode.

[0061] In summary, the above embodiments have detailed the manufacturing method of the metal electrode and the different configurations of the NMOS device. Of course, the above description is only a description of the preferred embodiment of the present invention, and is not any limitation to the scope of the present invention. The present invention includes but is not limited to the configurations listed in the above implementations. Those skilled in the art can draw inferences based on the contents of the above embodiments. Any changes and modifications made by ordinary technicians in the field of the present invention based on the above disclosure are within the scope of protection of the claims.

Claims

1. A method for manufacturing a metal electrode, It is characterized in that include: Providing a semiconductor structure, the semiconductor structure having a gate structure layer; Depositing a work function metal layer on the surface of the gate structure layer; Depositing a first barrier layer on the surface of the work function metal layer by vapor deposition, wherein the vapor deposition temperature is 25° C. to 340° C.; A metal layer is deposited on the surface of the first barrier layer as a contact electrode.

2. The method for producing a metal electrode according to claim 1, It is characterized in that Before depositing the first barrier layer, the method for manufacturing the metal electrode further comprises: A second barrier layer is deposited on the surface of the work function metal layer.

3. The method for manufacturing a metal electrode according to claim 1, It is characterized in that Depositing a first barrier layer on the surface of the work function metal layer by vapor deposition comprises: A first barrier layer is deposited on the surface of the work function metal layer by chemical vapor deposition, and the temperature of the chemical vapor deposition is 340°C.

4. The method for manufacturing a metal electrode according to claim 1, It is characterized in that Depositing a first barrier layer on the surface of the work function metal layer by vapor deposition comprises: A first barrier layer is deposited on the surface of the work function metal layer by physical vapor deposition, and the temperature of the physical vapor deposition is 25°C.

5. The method for making a metal electrode according to claim 2, It is characterized in that Depositing a second barrier layer on the surface of the work function metal layer comprises: A second barrier layer is deposited on the surface of the work function metal layer by vapor deposition, and the vapor deposition temperature is 275°C.

6. The method for manufacturing a metal electrode according to claim 1, It is characterized in that The material of the work function metal layer is TiAL alloy.

7. The method for manufacturing a metal electrode according to claim 1, It is characterized in that The material used for the first barrier layer is TiN.

8. The method for manufacturing a metal electrode according to claim 2, It is characterized in that The material of the second barrier layer is TaN, and the thickness of the second barrier layer is 1.5 nanometers.

9. The method for manufacturing a metal electrode according to claim 1, It is characterized in that The material of the metal layer deposited on the surface of the first barrier layer is metal tungsten.

10. An NMOS device, It is characterized in that include: The metal electrode is manufactured by the method for manufacturing a metal electrode as described in any one of claims 1 to 9.

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