Target material and manufacturing method thereof

Abstract

The invention discloses a target material and a manufacturing method thereof, the target material is suitable for a semiconductor manufacturing process, the target material comprises an alloy target material made of a first metal and a second metal, the target material comprises an upper section interval and a lower section interval, and the atomic ratio of the first metal to the second metal in the lower section interval is smaller than the atomic ratio of the first metal to the second metal. The atomic ratio of the first metal to the second metal in the upper section is different from that in the lower section.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor manufacturing technology, and in particular to a target material structure suitable for physical vapor deposition manufacturing technology and a manufacturing method thereof. Background Art

[0002] Vapor deposition is one of the commonly used manufacturing process steps for semiconductors, and can deposit various required material layers on a substrate located in a cavity.

[0003] In general semiconductor manufacturing processes, alloys are often used as deposition material layers. For example, the work function material layer in the gate often uses alloy materials. At this time, a target material made of alloy is selected and placed in the chamber. During physical vapor deposition, the target material is bombarded with inert gas ions, which will disperse the material particles in the air in the chamber and plate the material layer on the desired substrate. Summary of the invention

[0004] The present invention provides a target material suitable for use in a semiconductor manufacturing process, comprising a target material, an alloy made of a first metal and a second metal, wherein the target material comprises an upper section and a lower section, wherein the atomic ratio of the first metal to the second metal in the lower section is different from the atomic ratio of the first metal to the second metal in the upper section.

[0005] The present invention further provides a method for manufacturing a target material suitable for use in a semiconductor manufacturing process, comprising forming a target material, an alloy made of a first metal and a second metal, wherein the target material comprises an upper section and a lower section, wherein the atomic ratio of the first metal to the second metal in the lower section is different from the atomic ratio of the first metal to the second metal in the upper section.

[0006] The present invention provides a target material for a physical vapor deposition (PVD) manufacturing process in a semiconductor manufacturing process, wherein the target material includes two metals (such as titanium and aluminum), and the ratio of the two metals in the lower section of the target material is different from the ratio of the two metals in the upper section of the target material. The applicant has found that due to the different atomic weights of the metals, one of the metals (such as aluminum) is more likely to be bombarded and dispersed, and when the target material is used for a long time, it will affect the metal ratio of the deposited alloy layer. The present invention is characterized in that in the designed target material, the ratio of the two metals is adjusted with the height, so that the above-mentioned problem that one of the metals of the target material is more likely to be bombarded and dispersed due to the difference in atomic weight, thereby affecting the ratio of the deposited alloy layer, can be corrected, thereby improving the quality of the manufacturing process. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Figure 1A schematic diagram of the relationship between the ratio of aluminum and titanium in the titanium-aluminum alloy layer over a period of time for depositing a titanium-aluminum alloy layer using an existing titanium-aluminum alloy target;

[0008] Figure 2 is a schematic diagram of a target material according to a first embodiment of the present invention;

[0009] Figure 3 A schematic diagram of the relationship between the ratio of aluminum and titanium in the titanium-aluminum alloy layer over a period of time is provided for depositing a titanium-aluminum alloy layer using a titanium-aluminum alloy target material of the present invention;

[0010] Figure 4 FIG. 4 is a schematic diagram of a target material according to a second embodiment of the present invention.

[0011] Main component symbols

[0012] 1: Target

[0013] 2: Target

[0014] 10: Lower section

[0015] 10A: Lower section

[0016] 20: Middle section

[0017] 20A: Middle section

[0018] 30: Upper section

[0019] 30A: Upper section DETAILED DESCRIPTION

[0020] In order to enable a person skilled in the art to further understand the present invention, the preferred embodiments of the present invention are listed below, and the components and intended effects of the present invention are described in detail with reference to the accompanying drawings.

[0021] For the convenience of explanation, the drawings of the present invention are only for illustration to make it easier to understand the present invention, and the detailed proportions can be adjusted according to the design requirements. The upper and lower relationships of the relative elements in the drawings described in the text should be understood by those skilled in the art to refer to the relative positions of the objects, so they can be flipped to present the same components, which should all fall within the scope of the disclosure of this specification, and will be explained here first.

[0022] In the conventional steps, a target material and vapor deposition are used to deposit the required metal layer, for example, a titanium aluminum alloy (AlTi) target material is used to deposit the work function layer in the semiconductor gate.

[0023] The applicant has found that the titanium-aluminum alloy target in the existing steps has some disadvantages. First, since the atomic weight of aluminum (27) is less than that of titanium (48), the weight of aluminum atoms is lighter. When the target is bombarded with inert gas ions (such as argon ions) during the PVD step, aluminum atoms are more likely to be knocked out and dispersed into the cavity and deposited as titanium-aluminum alloy than titanium atoms. The above situation will become more obvious as the target is used for a longer time. Please refer to Figure 1 , Figure 1 A schematic diagram showing the relationship between the ratio of aluminum to titanium in the titanium-aluminum alloy layer over a period of time is shown using an existing titanium-aluminum alloy target to deposit a titanium-aluminum alloy layer. Figure 1 As shown, the horizontal axis is time, and the vertical axis is the measured atomic ratio of aluminum to titanium. The value of the vertical axis varies between 1.7 and 2. This value is measured by a metrology tool called HKXPS to measure the number of aluminum and titanium atoms per unit area in the titanium-aluminum alloy layer deposited on the wafer, and then the ratio is calculated by dividing them. It can be found that with time, the ratio of aluminum in the titanium-aluminum alloy layer gradually increases. At this time, the target material needs to be replaced to restore the atomic ratio of aluminum to titanium to normal (such as Figure 1 As shown in the figure, the low point formed by the sudden drop in each rising process is the time to replace the target material). In other words, the applicant measured the deposited titanium-aluminum alloy layer and found that as the target material was used, the proportion of aluminum in the titanium-aluminum alloy layer gradually increased until the proportion of aluminum in the titanium-aluminum alloy layer exceeded a specified upper limit, indicating that the formed titanium-aluminum alloy layer no longer met the specifications, and it was necessary to replace the target material with a new one before the target material was used up, which also caused a waste of materials.

[0024] Please refer to Figure 2 , which is a schematic diagram of a target material according to a first embodiment of the present invention, such as Figure 2 As shown, the target material 1 provided by the present invention is a target material suitable for semiconductor physical vapor deposition (PVD), which contains at least two metals. In the present invention, aluminum and titanium are taken as examples, that is, the main material of the target material 1 is titanium aluminum alloy (AlTi). After the physical vapor deposition step, a titanium aluminum alloy layer can also be formed on the target substrate, which can be used for the work function layer in the semiconductor manufacturing process.

[0025] The target material 1 of the present invention includes a plurality of different intervals, such as a lower interval 10, a middle interval 20 and an upper interval 30. The ratios of aluminum to titanium contained in the lower interval 10, the middle interval 20 and the upper interval 30 are different. For example, in the lower interval 10, the ratio of aluminum to titanium is about 50:50, while in the middle interval 20, the ratio of aluminum to titanium is about 30:70 (that is, the ratio of aluminum decreases), and in the upper interval 30, the ratio of aluminum to titanium is about 20:80 (that is, the ratio of aluminum decreases again), but the above ratio is only one example of the present invention, and the present invention is not limited thereto. As long as the ratios of the two metal atoms in different intervals are different from each other, they should all fall within the scope of the present invention.

[0026] When the target material 1 is used for physical vapor deposition, the target material will be consumed first from the lower section 10, and then the middle section 20 and the upper section 30 will be consumed in sequence. Figure 1 It is observed that since aluminum is more easily bombarded during the physical vapor deposition step and dispersed into the air and deposited as a titanium-aluminum alloy layer, the aluminum content in the titanium-aluminum alloy layer gradually increases. Therefore, as the target material 1 designed by the present invention is used over time, the aluminum content contained in the target material 1 itself gradually decreases, thereby offsetting or compensating for the above-mentioned problem of gradually increasing aluminum content.

[0027] The target material 1 provided by the present invention has been found to have improved Figure 1 The problem of gradually increasing aluminum content in the titanium aluminum alloy layer is shown. Figure 3 A schematic diagram showing the relationship between the ratio of aluminum to titanium in the titanium-aluminum alloy layer over a period of time is shown using a titanium-aluminum alloy target material of the present invention to deposit a titanium-aluminum alloy layer. Figure 3 As shown, the aluminum content in the titanium-aluminum alloy layer does not increase significantly, so the manufacturing process conditions can be stabilized, and there is no need to replace the target material in advance before the target material is consumed, which also saves costs.

[0028] In actual production, the titanium-aluminum alloy target 1 of the present invention can be formed by blending and pressing aluminum powder and titanium powder. For example, aluminum powder and titanium powder in roughly the same proportion can be first blended to form a titanium-aluminum mixed powder with an aluminum-to-titanium ratio of about 50:50, and then the titanium-aluminum mixed powder is pressed to form a titanium-aluminum alloy layer constituting the lower section 10. Then, the above steps can be repeated to form other multiple layers of titanium-aluminum alloy in the same manner and stacked thereon. However, it is worth noting that as the height of the titanium-aluminum alloy layer increases, that is, gradually increases from the lower section 10 to the middle section 20 or the upper section 30, it is necessary to adjust the ratio of the mixed aluminum powder and titanium powder, that is, gradually reduce the ratio of aluminum powder. In this way, the following can be produced: Figure 2 The target material 1 is shown.

[0029] Please refer to Figure 4 , which is a schematic diagram of a target material according to a second embodiment of the present invention, such as Figure 4 As shown, the target material 2 of this embodiment is similar to the above Figure 2 The target material 1 shown in the figure is different in that the proportion of aluminum in the target material 2 in this embodiment decreases gradually as the height increases. To be more specific, the target material 2 includes a lower section 10A, a middle section 20A, and an upper section 30A. The ratio of aluminum to titanium in different sections is different. In addition, in the same section (taking the lower section 10A as an example), the ratio of aluminum to titanium also decreases gradually and continuously as the height increases. Therefore, in this embodiment, near the boundaries between different sections, the ratio of aluminum changes more slowly, and will not change as much as in the previous embodiment. Figure 2 The ratio of aluminum in the embodiment shown suddenly drops significantly. The method for making the target material 2 of this embodiment is also similar to the above description. Aluminum powder and titanium powder in different ratios are repeatedly blended and pressed to form a target material 2. Figure 4 The remaining features of the target material 2 shown are the same as those described above and will not be repeated here.

[0030] In addition, although the target material in the above embodiment is divided into three sections, namely, the upper section, the middle section and the lower section, the present invention does not limit the number of sections, that is, more or fewer sections may be formed in other embodiments, which also fall within the scope of the present invention.

[0031] In addition, although titanium-aluminum alloy is used as an example of the target material in this embodiment, the present invention can also be applied to other types of alloy targets, such as antimony-telluride, titanium-chromium, titanium-silicon, chromium-molybdenum, nickel-chromium, nickel-vanadium, nickel-copper, chromium-tungsten, chromium-vanadium, terbium-iron-cobalt and other alloy targets. As long as the atomic weights of two or three metals in the alloy have a certain degree of difference, they can be applied to the scope of the present invention.

[0032] In summary, the present invention provides a target material 1 suitable for use in a semiconductor manufacturing process, comprising a target material, wherein the target material 1 is an alloy made of a first metal (e.g., aluminum) and a second metal (e.g., titanium), wherein the target material 1 comprises an upper section 30 and a lower section 10, wherein the atomic ratio of the first metal to the second metal in the lower section 10 is different from the atomic ratio of the first metal to the second metal in the upper section 30.

[0033] In some embodiments of the present invention, the first metal comprises aluminum and the second metal comprises titanium.

[0034] In some embodiments of the present invention, in the lower section 10, the atomic ratio of the first metal to the second metal is 1:1.

[0035] In some embodiments of the present invention, in the upper section 30, the atomic percentage of the first metal to the second metal is less than 0.3 (for example, the ratio of aluminum to titanium is 20:80, so 20 / 80<0.3).

[0036] In some embodiments of the present invention, the target further includes a middle section 20 located between the upper section 30 and the lower section 10 .

[0037] In some embodiments of the present invention, in the target material 2, the atomic percentage values ​​of the first metal and the second metal decrease gradually from the lower section 10A, the middle section 20A to the upper section 30A (e.g. Figure 4 embodiment shown).

[0038] In some embodiments of the present invention, the atomic percentages of the first metal and the second metal in the target material 1 are fixed values ​​(e.g. Figure 2 embodiment shown).

[0039] In some embodiments of the present invention, the target material is used in a physical vapor deposition (PVD) machine.

[0040] The present invention further provides a method for manufacturing a target material suitable for use in a semiconductor manufacturing process, comprising forming a target material 1, wherein the target material 1 is an alloy made of a first metal (e.g., aluminum) and a second metal (e.g., titanium), wherein the target material comprises an upper section 30 and a lower section 10, wherein the atomic ratio of the first metal to the second metal in the lower section 10 is different from the atomic ratio of the first metal to the second metal in the upper section 30.

[0041] In some embodiments of the present invention, the method for forming a target material further includes providing a first metal powder (e.g., aluminum powder) and a second metal powder (e.g., titanium powder), mixing them with each other in a first ratio (e.g., approximately 50:50), performing a pressing step to form a first alloy layer from the first metal powder and the second metal powder, providing the first metal powder and the second metal powder again, mixing them with each other in a second ratio, wherein the second ratio is different from the first ratio (e.g., a ratio of 30:70 or 20:80), performing another pressing step to form a second alloy layer from the first metal powder and the second metal powder, and stacking it on the first alloy layer.

[0042] In some embodiments of the present invention, in the first ratio, the percentage of the total volume occupied by the first metal (eg, 50%) is greater than the percentage of the total volume occupied by the first metal in the second ratio (eg, 20%).

[0043] The present invention provides a target material for a physical vapor deposition (PVD) manufacturing process in a semiconductor manufacturing process, wherein the target material includes two metals (such as titanium and aluminum), and the ratio of the two metals in the lower section of the target material is different from the ratio of the two metals in the upper section of the target material. The applicant has found that due to the different atomic weights of the metals, one of the metals (such as aluminum) is more likely to be bombarded and dispersed, and when the target material is used for a long time, it will affect the metal ratio of the deposited alloy layer. The present invention is characterized in that in the designed target material, the ratio of the two metals is adjusted with the height, so that the above-mentioned problem that one of the metals of the target material is more likely to be bombarded and dispersed due to the difference in atomic weight, thereby affecting the ratio of the deposited alloy layer, can be corrected, thereby improving the quality of the manufacturing process.

[0044] The above descriptions are only preferred embodiments of the present invention. All equivalent changes and modifications made according to the claims of the present invention should fall within the scope of the present invention.

Claims

1. A target material suitable for use in a semiconductor manufacturing process, comprising: A target material, which is an alloy made of a first metal and a second metal, wherein the target material includes an upper section and a lower section, wherein the atomic ratio of the first metal to the second metal in the lower section is different from the atomic ratio of the first metal to the second metal in the upper section. 2 . The target material as claimed in claim 1 , wherein the first metal comprises aluminum, and the second metal comprises titanium. 3 . The target material as claimed in claim 1 , wherein in the lower section, the atomic ratio of the first metal to the second metal is 1:

1. The target material as claimed in claim 1 , wherein in the upper section, the atomic percentage of the first metal and the second metal is less than 0.

3. 5 . The target material as claimed in claim 1 , wherein the target material further comprises a middle section located between the upper section and the lower section. 6 . The target material as claimed in claim 5 , wherein the atomic percentage values ​​of the first metal and the second metal decrease gradually from the lower section, the middle section to the upper section. 7 . The target material as claimed in claim 5 , wherein in any one of the lower section, the middle section or the upper section, the atomic percentages of the first metal and the second metal are fixed values. 8 . The target material as claimed in claim 1 , wherein the target material is used in a physical vapor deposition (PVD) machine.

9. A method for producing a target material suitable for use in a semiconductor manufacturing process, comprising: A target material is formed, which is an alloy made of a first metal and a second metal, wherein the target material includes an upper section and a lower section, wherein the atomic ratio of the first metal to the second metal in the lower section is different from the atomic ratio of the first metal to the second metal in the upper section. 10 . The method for manufacturing a target material as claimed in claim 9 , wherein the first metal comprises aluminum, and the second metal comprises titanium. 11 . The method for manufacturing a target material as claimed in claim 9 , wherein in the lower section, the atomic ratio of the first metal to the second metal is 1:

1. 12 . The method for manufacturing a target material as claimed in claim 9 , wherein in the upper section, the atomic percentage of the first metal and the second metal is less than 0.

3. 13 . The method for manufacturing a target material as claimed in claim 9 , wherein the target material further comprises a middle section located between the upper section and the lower section. 14 . The method for manufacturing a target material as claimed in claim 13 , wherein the atomic percentage values ​​of the first metal and the second metal decrease gradually from the lower section, the middle section to the upper section. 15 . The method for manufacturing a target material as claimed in claim 13 , wherein in any one of the lower section, the middle section or the upper section, the atomic percentages of the first metal and the second metal are fixed values. 16 . The method for manufacturing a target material as claimed in claim 9 , wherein the target material is used in a physical vapor deposition (PVD) machine.

17. The method for manufacturing a target material as claimed in claim 9, wherein the method for forming the target material further comprises: Providing a first metal powder and a second metal powder, and mixing them with each other in a first ratio; Performing a pressing step to form the first metal powder and the second metal powder into a first alloy layer; Providing the first metal powder and the second metal powder again, and mixing them with each other in a second ratio, wherein the second ratio is different from the first ratio; Another pressing step is performed to make the first metal powder and the second metal powder into a second alloy layer, and stack the second alloy layer on the first alloy layer. 18 . The method for manufacturing a target material as claimed in claim 17 , wherein the percentage of the total volume occupied by the first metal in the first ratio is greater than the percentage of the total volume occupied by the first metal in the second ratio.

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