阅读说明：本技术 改善深孔填充均匀性的靶材组件、溅射设备及设计方法 (Target assembly for improving deep hole filling uniformity, sputtering equipment and design method ) 是由 陈东伟 周云 宋维聪 于 2021-08-13 设计创作，主要内容包括：本发明涉及改善深孔填充均匀性的靶材组件、溅射设备及设计方法,包括靶材本体,所述靶材本体为溅射面是凹弧面的半球形,所述靶材本体的背面安装于靶材背板上,所述靶材背板另一侧设置有磁性部,所述靶材本体、靶材背板和磁性部同轴设置,且所述靶材背板及磁性部与所述靶材本体的溅射面的形状相匹配。设备还包括箱体和加热器,靶材组件的形状通过设计方法得出。本发明的靶材组件能够提高对基片上深孔填充的均匀性；溅射设备在保证填充均匀性的同时,减小了薄膜的内应力,提高成膜的致密度；设计方法,操作简单,得到的靶材组件填充均匀性好。(The invention relates to a target assembly for improving deep hole filling uniformity, sputtering equipment and a design method. The equipment also comprises a box body and a heater, and the shape of the target assembly is obtained by a design method. The target material assembly can improve the uniformity of filling the deep hole on the substrate; the sputtering equipment reduces the internal stress of the film and improves the film-forming density while ensuring the filling uniformity; the design method is simple to operate, and the obtained target material assembly is good in filling uniformity.)

1. The target assembly for improving the filling uniformity of the deep hole is characterized by comprising a target body, wherein the target body is hemispherical, the sputtering surface of the target body is a concave arc surface, the back surface of the target body is installed on a target back plate, a magnetic part is arranged on the other side of the target back plate, the target body, the target back plate and the magnetic part are coaxially arranged, and the target back plate and the magnetic part are matched with the sputtering surface of the target body in shape.

2. The target assembly for improving deep hole filling uniformity of claim 1, wherein the chord length of the cross-sectional arc of the target body is fixed, and the angle of the cross-sectional arc is 0-90 °.

3. The target assembly for improving deep hole filling uniformity of claim 2, wherein the angle of said cross-sectional arc is 27 ° -33 °.

4. The target assembly for improving deep hole filling uniformity of claim 1, wherein the magnetic portion is mounted in a cover plate, the target backing plate seals the opening of the cover plate, the magnetic portion comprises a magnet body and a rotating motor, and the rotating motor passes through the cover plate and is connected with the magnet body.

5. The target assembly for improving the filling uniformity of the deep hole according to claim 4, wherein a plurality of the magnet bodies are provided, the plurality of the magnet bodies are uniformly mounted on a rotating bracket, the polarities of the adjacent magnet bodies are opposite, and the rotating motor is connected with the rotating bracket.

6. The target assembly for improving deep hole filling uniformity of claim 5, wherein the rotating support is a double-layer cross support, and the magnet body is clamped between the double-layer cross support.

7. Sputtering equipment for improving deep hole filling uniformity, which is characterized by comprising the target assembly according to any one of claims 1 to 6, wherein the target assembly is arranged in a box body, a heater opposite to the target assembly is further arranged in the box body, and the heater penetrates through the box body.

8. A method of designing a target assembly for improving deep hole filling uniformity according to any of claims 1-6, comprising the steps of:

determining the total radius of the target body according to the size of sputtering equipment;

selecting parameters influencing the concave shape of the target body, and respectively selecting a plurality of numerical values for designing the shapes of the target body, the target back plate and the magnetic part according to each parameter;

verifying the target material assembly corresponding to each numerical value;

and determining the optimal shape of the target body by observing and calculating the distribution condition of the deposition thickness in the holes on the outer side of the sample wafer.

9. The method of claim 8, wherein the parameters affecting the concave shape of the target body are selected to include an angle of a cross-sectional arc of the hemispherical target body, and a plurality of angle parameters are selected for verification.

10. The method according to claim 8, wherein the distribution K of the deposition thickness in the outer hole is calculated as follows:

K＝c/d

wherein c is the thinnest thickness of the sample deep hole at the same height, and d is the thickest thickness of the sample deep hole at the same height.

Technical Field

The invention relates to the technical field of physical vapor deposition, in particular to a target assembly for improving deep hole filling uniformity, sputtering equipment and a design method.

Background

In the advanced very large scale integrated circuits (VLSI) industry, the manufacturing process has advanced to 1-2 cm²Designing hundreds of thousands of Metal Oxide Semiconductor (MOS) crystals on the silicon surface with area, even more than millions of MOS crystalsBody tubes, etc. The metallization and interconnection processes are used to make contact (contact) between the devices, such as three electrodes on the MOS devices, and between the metal layers, and it is necessary to electrically connect the conductive wires that have been in contact with the respective MOS devices by using the conductive wires according to the circuit route of the circuit design to form a complete circuit (circuit), thereby forming a complete electronic device.

In the current VLSI process technology, the two main types of conductor materials used for contacts and metal interconnects are tungsten (tungsten) metal and copper (Cu), and the copper process refers to a series of semiconductor manufacturing processes using copper as the metal interconnect material. The process of copper wiring includes deposition of barrier layer (barrier) and seed layer (seed) in via/recess structures and electroplating of copper.

At present, the deposition of the barrier layer and the seed layer in the through hole/deep hole structure is mainly manufactured by Physical Vapor Deposition (PVD) long-range sputtering, which has the advantage of good conductive effect, but relatively speaking, copper has the disadvantages of easy oxidation, easy diffusion and the like. The diffusion of copper into the dielectric can affect transistor performance and, for reliability reasons, to prevent copper diffusion into silicon and/or silicon dioxide, it is necessary to deposit a reliable barrier layer of tantalum nitride over the via, followed by a layer of tantalum to increase copper adhesion, and then a very thin layer of copper as a conductive dielectric for ECP and also as a nucleation layer for metal crystal growth for copper electroplating.

In the coating apparatus of the prior art, the target is generally in a circular planar shape, and the lower wafer is placed on the heater. In the coating process, because the concentrations of sputtered particles from the target material at the center of the wafer and at the edge of the wafer are different, the directions of the sputtered particles to the surface of the wafer are also different, the filling of the side wall of the deep hole structure at the edge of the wafer is easy to cause the condition that one side is thick and the other side is thin, so that the uniformity of the filling of the tantalum nitride barrier layer and the copper seed layer in the deep hole is poor, and serious asymmetry is caused.

Disclosure of Invention

Therefore, the technical problem to be solved by the invention is to overcome the defect of uneven sputtering of the side wall in the through hole/deep hole in the prior art, and provide a target material, sputtering equipment and a design method for improving the deep hole filling uniformity, so that the deep hole filling on the substrate is more uniform.

In order to solve the technical problem, the invention provides a target assembly for improving the filling uniformity of a deep hole, which comprises a target body, wherein the target body is hemispherical with a concave arc surface, the back surface of the target body is arranged on a target back plate, a magnetic part is arranged on the other side of the target back plate, the target body, the target back plate and the magnetic part are coaxially arranged, and the shapes of the target back plate and the magnetic part are matched with the sputtering surface of the target body.

In one embodiment of the invention, the chord length of the cross-sectional arc of the target body is fixed, and the angle of the cross-sectional arc is 0-90 degrees.

In one embodiment of the invention, the angle of the cross-sectional arc is between 27 ° and 33 °.

In one embodiment of the present invention, the magnetic part is installed in a cover plate, the target backing plate seals the opening of the cover plate, and the magnetic part includes a magnet body and a rotating motor, and the rotating motor penetrates through the cover plate and is connected with the magnet body.

In one embodiment of the invention, the magnet bodies are provided in plurality, the magnet bodies are uniformly arranged on a rotating bracket, the polarities of the adjacent magnet bodies are opposite, and the rotating motor is connected with the rotating bracket.

In one embodiment of the invention, the rotating bracket is a double-layer cross bracket, and the magnet body is clamped between the double-layer cross bracket.

The invention also provides sputtering equipment for improving the filling uniformity of the deep hole, which comprises the target material assembly, wherein the target material assembly is arranged in the box body, the box body is also internally provided with a heater opposite to the target material assembly, and the heater penetrates through the box body.

The invention further provides a method for designing the target material assembly for improving the deep hole filling uniformity, which comprises the following steps:

determining the total radius of the target body according to the size of sputtering equipment;

selecting parameters influencing the concave shape of the target body, and respectively selecting a plurality of numerical values for designing the shapes of the target body, the target back plate and the magnetic part according to each parameter;

verifying the target material assembly corresponding to each numerical value;

and determining the optimal shape of the target body by observing and calculating the distribution condition of the deposition thickness in the holes on the outer side of the sample wafer.

In one embodiment of the present invention, the parameters affecting the concave shape of the target body are selected to include the angle of the cross-sectional arc of the hemispherical target body, and a plurality of angle parameters are selected for verification.

In one embodiment of the present invention, the distribution K of the deposition thickness in the outside hole is calculated by the following formula:

K＝c/d

wherein c is the thinnest thickness of the sample deep hole at the same height, and d is the thickest thickness of the sample deep hole at the same height.

Compared with the prior art, the technical scheme of the invention has the following advantages:

the target material assembly can improve the uniformity of filling the deep hole on the outer side of the substrate;

the sputtering equipment disclosed by the invention has the advantages that the filling uniformity is ensured, the internal stress of the film is reduced, and the film-forming density is improved;

the design method of the target assembly obtained by the invention is simple to operate, and the obtained target assembly has good deep hole filling uniformity.

Drawings

In order that the present disclosure may be more readily and clearly understood, reference is now made to the following detailed description of the embodiments of the present disclosure taken in conjunction with the accompanying drawings, in which

FIG. 1 is a schematic view of the overall structure of the present invention;

fig. 2 is a cross-sectional view of a target assembly of the present invention;

FIG. 3 is a schematic view of the magnetic portion of the present invention;

FIG. 4 is a schematic view of a sputtering apparatus of the present invention;

fig. 5 is a cross-sectional view of a sputtering apparatus of the present invention.

The specification reference numbers indicate: 1. a target assembly; 10. a target material body; 20. a back plate; 30. a magnetic part; 31. a cover plate; 32. a magnet body; 33. a rotating electric machine; 34. rotating the bracket; 2. a sputtering apparatus; 3. a box body; 4. a heater.

Detailed Description

The present invention is further described below in conjunction with the following figures and specific examples so that those skilled in the art may better understand the present invention and practice it, but the examples are not intended to limit the present invention.

Referring to fig. 1, a schematic diagram of a target assembly 1 for improving deep hole filling uniformity according to an embodiment of the present invention is shown. The target assembly 1 in this embodiment includes a target body 10, the target body 10 is a hemisphere whose sputtering surface is a concave arc surface, the back surface of the target body 10 is installed on a target backing plate 20, a magnetic portion 30 is disposed on the other side of the target backing plate 20, the target body 10, the target backing plate 20 and the magnetic portion 30 are coaxially disposed, and the sputtering surface shape of the target backing plate 20 and the magnetic portion 30 are matched with that of the target body 10.

In this embodiment, the target backing plate 20 is used to fix the target body 10, the magnetic portion 30 is used to generate a magnetic field, and during sputtering, a reaction gas, usually Ar gas, is ionized into positive ions and new electrons under the action of the electric field; new electrons fly to the substrate, and the Ar ions accelerate to the target body 10 under the action of the electric field and bombard the surface of the target body 10 at high energy, so that the target body 10 is sputtered. In the sputtered particles, neutral target atoms or molecules are deposited on the substrate to form a thin film. Electrons are constrained in a plasma region on the surface of the target body 10 to do circular motion under the action of a magnetic field, and a large amount of Ar ions are ionized in the region to bombard the target body 10, so that high deposition rate is realized. In the process of coating, the concentrations of sputtered particles from a target material at the center of the substrate and the edge of the substrate are different, and the directions of the sputtered particles to the surface of the substrate are also different, so that the situation that one side of the side wall of a deep hole structure at the edge of the substrate is thick and the other side of the side wall is thin is easy to occur in the aspect of probability, the uniformity of filling a film layer in the deep hole is poor, and serious asymmetry is caused. Therefore, the target body 10 is configured to have a concave arc surface, and in this embodiment, the target body 10 is specifically configured to be hemispherical. It should be noted that the hemispherical shape in the present embodiment only illustrates that the target body 10 is a partial spherical surface, but the target body 10 is not limited to 1/2 spherical. When the Ar ions bombard the surface of the target body 10, most of the sputtered particles fly out along the normal direction of the sputtering surface, in this embodiment, because the sputtering surface of the target body 10 is a concave arc surface, an included angle exists between the surface of the target body 10 and the surface of the substrate, so the normal direction of the target body 10 is not perpendicular to the surface of the substrate, but converges towards the center of the substrate, and meanwhile, the normal direction of the target body 10 continuously changes, so that the sputtered particles fly out from multiple angles, thereby the periphery of the deep hole can be filled, the situation that the side wall of the deep hole is thin at one side and thick at the other side due to the sputtered particles flying out along one direction in the planar target material can be avoided, and the deep hole can be filled uniformly. Meanwhile, the magnetic part 30 and the target back plate 20 are coaxially arranged with the target body 10 and are matched with the sputtering surface of the target body 10 in shape, so that the distance between the sputtering surfaces of the magnetic part 30 and the target body 10 is ensured to be constant, the magnetic field intensity formed around the target body 10 is ensured to be constant all the time, the magnetic field around the target body 10 is uniform, electrons bound on the surface of the target body 10 are prevented from being reduced, the concentration of Ar ions ionized by the electrons is prevented from being reduced, and the sputtering uniformity is improved. The substrate in this embodiment includes, but is not limited to, a wafer.

Furthermore, in the invention, a reliable tantalum nitride barrier layer is deposited on the deep hole, so that a layer of tantalum nitride is coated on the sputtering surface of the target body 10, the tantalum nitride layer has larger stress, and the tantalum nitride layer can be attached to the target body 10 because the surface of the concave arc surface is smooth and no stress mutation area exists.

Referring to fig. 2, a schematic cross-sectional view of a target assembly of the present invention is shown. The chord length f of the cross-sectional arc of the target body 10 is determined by the size of the sputtering apparatus 2, and therefore the chord length f is fixed, and when the chord length f is fixed, the factor influencing the curvature of the target body 10 is the arc length L of the cross-sectional arc, the arc length L is determined by the radius H of the circle in which the cross-sectional arc is located, and the angle δ corresponding to the cross-sectional arc is L/2 pi H, and f is 2Hsin δ/2, so the arc length L is δ f/(2sin δ/2). In the illustrated embodiment, the angle δ of the cross-sectional arc is approximately in the range of 0-90. δ may be about 10 °, 20 °, 30 °, 40 °, 50 °, 60 °, 70 °, 80 ° or 90 °, by experiment, it can be found that the optimal angular range of the cross-sectional arc is 27 ° -33 °. Within this angular range, the deposition thickness within the pores is most uniform.

Referring to fig. 3, a magnetic part 30 according to the present invention is shown. In this embodiment, the magnetic portion 30 is installed in the cover plate 31, and the target backing plate 20 seals the opening of the cover plate 31, so that the magnetic portion 30 is sealed between the cover plate 31 and the target body 10, and the magnetic field generated by the magnetic portion 30 is prevented from being influenced by the external environment. Since the magnetic field is not completely uniform, which affects the utilization efficiency and sputtering uniformity of the target body 10, in the present embodiment, a rotating magnetic field is provided, and the magnetic portion 30 includes a magnet body 32 and a rotating motor 33, and the rotating motor 33 is connected to the magnet body 32 through the cover plate 31 in order to fix the magnet body 32. That is, the rotating electrical machine 33 is attached to the cover plate 31, and the magnet body 32 connected to the rotating electrical machine 33 is fixed. Since the magnetic field forms a magnetic field track between two opposite magnetic poles, the sputtering efficiency of the target material directly below the magnetic field track is high, and the sputtering efficiency of the target material in other areas is low, so in order to improve the utilization efficiency of the target material body 10, in the present embodiment, a plurality of the magnet bodies 32 are uniformly installed on the rotating bracket 34, the polarities of the adjacent magnet bodies 32 are opposite, and the rotating motor 33 is connected to the rotating bracket 34. The arrangement of the plurality of magnet bodies 32 enables the distribution of the magnetic field to be wider and more uniform, and improves the service efficiency of the target material body 10. Further, because the rotating bracket 34 and the magnet body 32 have a certain weight, in order to balance the stress of the rotating motor 33 and prolong the service life of the rotating motor 33, the rotating bracket 34 is a double-layer cross bracket, and the magnet body 32 is clamped between the double-layer cross bracket. On the one hand, the magnet body 32 is more firmly mounted and does not separate from the support even if continuously rotated, and on the other hand, the magnetic field is more dense and uniform.

Referring to fig. 4 and 5, a sputtering apparatus for improving deep hole filling uniformity according to the present invention is shown. The sputtering equipment 2 comprises the target material assembly 1, wherein the target material assembly 1 is arranged in a box body 3, a heater 4 opposite to the target material assembly 1 is also arranged in the box body 3, and the heater 4 penetrates through the box body 3 to be connected with a power supply. By adopting the target material body 10 with the concave arc-shaped sputtering surface, the deposition of sputtering particles in deep holes on the substrate is more uniform.

The invention also discloses a method for designing the target material assembly for improving the deep hole filling uniformity, which comprises the following steps:

determining the total radius of the target body according to the size of sputtering equipment; the total radius is the vertical distance from the axis of the target body to its edge, the length is determined by the equipment and is a determined value from which other parameters of the final shape of the target body can be determined.

The total radius determines the size of the periphery of the target body, and the specific shape of the target body is related to other parameters, so that parameters influencing the concave shape in the target body are continuously selected, and the shapes of the target body, the target back plate and the magnetic part are respectively designed by selecting a plurality of numerical values according to each parameter; therefore, different target assemblies can be obtained, theoretically, each target assembly has the effect of improving the sputtering uniformity, but the effects are different, so experimental verification is needed.

Verifying the target material assembly corresponding to each numerical value; in the embodiment of the present invention, since the target body is hemispherical, the selected parameter affecting the shape of the target body includes an angle δ of a cross-sectional arc of the target body, in the embodiment, δ is verified by selecting a plurality of values from 0 ° to 90 °, and the two values are separated by 10 °. Observing the same height position in the hole at the outer side of the sample wafer, when the difference between the thinnest position and the thickest position is minimum, the delta value is 20-40 degrees, then reducing the change range of the delta value, finally obtaining the optimal angle range of the section arc which is 27-33 degrees, calculating the arc length of the section arc according to L ═ delta f/(2sin delta/2), and determining the optimal shape of the target body. In order to determine the uniformity of the filling film layer more intuitively, the constant K is defined to represent the distribution condition of the deposition thickness in the outer hole, wherein K is equal to c/d, wherein c is the thinnest thickness of the sample deep hole at the same height, and d is the thickest thickness of the sample deep hole at the same height.

It should be understood that the above examples are only for clarity of illustration and are not intended to limit the embodiments. Other variations and modifications will be apparent to persons skilled in the art in light of the above description. And are neither required nor exhaustive of all embodiments. And obvious variations or modifications therefrom are within the scope of the invention.