TWI834028B - Physical vapor deposition chamber, method for depositing film, and method for forming semiconductor structure - Google Patents

Abstract

A physical vapor deposition chamber includes a chamber, a wafer support, a cover ring, and a shield. The wafer support is disposed on a bottom of the chamber. The cover ring surrounds the wafer support and is electrically insulated from the wafer support. The shield surrounds a chamber wall of the physical vapor deposition chamber. The shield includes a first vertical portion, a second vertical portion, and a horizontal portion. The first vertical portion is substantially parallel to the chamber wall of the physical vapor deposition chamber, and the cover ring is disposed between the first vertical portion and the wafer support. The first vertical portion is separated from an outer side wall of the cover ring by about 2.3 mm to about 2.7 mm. The second vertical portion is disposed below the cover ring, and a top end of the second vertical portion is substantially in direct with contact with the cover ring. The horizontal portion is disposed below the cover ring and connects a first bottom end of the first vertical portion and a second end of the second vertical portion.

Description

Physical vapor deposition apparatus, method of depositing thin film, and method of forming semiconductor structure

The present disclosure relates to a physical vapor deposition apparatus, a method of depositing a thin film, and a method of forming a semiconductor structure.

Physical vapor deposition (PVD) is a well-known process for depositing thin films of materials on substrates and is commonly used to manufacture semiconductor devices. The physical vapor deposition process is performed under high vacuum in a chamber that receives a substrate (eg, a wafer) and contains a solid source or plate of material to be deposited on the substrate. Therefore, the solid source or plate of material is called a physical vapor deposition target. In the physical vapor deposition process, the physical vapor deposition target material is physically converted from a solid into a gas. The target gas is transported from the physical vapor deposition target to the substrate, where it is deposited as a thin film on the substrate.

There are many methods of achieving physical vapor deposition, including evaporation, electron beam evaporation, plasma spray deposition and sputtering. Currently, sputtering is the most commonly used method to achieve physical vapor deposition. During sputtering, a plasma is generated in the chamber and directed to the physical vapor deposition target. Due to collisions with high-energy particles (ions) of the plasma, the plasma physically displaces or erodes (sputters) atoms or molecules from the reaction surface of the physical vapor deposition target into the gas of the target. The gas with sputtered atoms or molecules of the target material is transported to the substrate through a reduced pressure zone and deposited on the substrate to form a thin film containing the target material.

One aspect of the present disclosure provides a physical vapor deposition device including a chamber, a base, a cover ring, and a barrier. The base is arranged at the bottom of the chamber. The cover ring surrounds the base and is electrically insulated from the base. The barrier surrounds the chamber walls of the physical vapor deposition apparatus. The barrier includes a first vertical portion, a second vertical portion, and a horizontal portion. The first vertical portion is substantially parallel to the chamber wall of the physical vapor deposition device, and the cover ring is located between the first vertical portion and the base, wherein the first vertical portion is spaced a first distance from the outer sidewall of the cover ring, and the first The distance is between 2.3 mm and 2.7 mm. The second vertical portion is located below the cover ring, wherein a top end of the second vertical portion contacts the cover ring. The horizontal portion is located below the cover ring and connects the first bottom end of the first vertical portion and the second bottom end of the second vertical portion.

Another aspect of the present disclosure is to provide a method for depositing a thin film, including the following operations. A wafer is received in a physical vapor deposition apparatus. The process gas is introduced through the gas channel, and the process gas flows from the bottom of the base through the recess of the cover ring and through a channel between the barrier and the outer side wall of the cover ring, and flows upward into the chamber. Energy is delivered into the chamber to form a plasma from the process gas, wherein the energy is provided by a radio frequency source and a direct current source. The plasma is bombarded with the target material in the physical vapor deposition device. Deposit a thin film onto the surface of the wafer.

Another aspect of the present disclosure is to provide a method of forming a semiconductor structure, including the following operations. Deposit a dielectric layer on the underlying structure. An opening is formed through the dielectric layer. A work function layer is formed in the opening. Depositing a first cobalt thin film layer in the opening in a physical vapor deposition device, and the first cobalt thin film layer is located on the work function layer, wherein depositing the first cobalt thin film layer includes allowing a process gas to flow through the gap between the barrier and the cover ring A flow rate is between about 400 sccm and about 450 sccm. A second cobalt thin film layer is formed to cover the first cobalt thin film layer and the sidewall of the opening. A third cobalt film is formed to cover the second cobalt film layer.

In order to make the description of the present disclosure more detailed and complete, the following provides an illustrative description of the implementation aspects and specific embodiments of the present disclosure; however, this is not the only form of implementing or using the specific embodiments of the present disclosure. The embodiments disclosed below can be combined or replaced with each other under beneficial circumstances, and other embodiments can be added to one embodiment without further description or explanation.

The following disclosure provides many different embodiments or examples for implementing different features of various embodiments of the present disclosure. The following content describes specific examples of each component and its arrangement to simplify the explanation. Of course, these specific examples are not limiting. For example, in the following description, a first member formed over or on a second member may include embodiments in which the first member and the second member are formed in direct contact, and may also include embodiments in which additional members may be formed on the first member. An embodiment in which the first member and the second member are not in direct contact with the second member. Additionally, the present disclosure may repeat reference symbols and/or letters in various examples. This repetition is for purposes of simplicity and clarity and does not by itself indicate a relationship between the various embodiments and/or configurations discussed.

In addition, for ease of description, spatially relative terms (such as “below,” “below,” “lower,” “above,” “upper,” “on,” and the like) may be used herein. To describe the relationship between one element or component and another element or component, as shown in the figure. In addition to the orientation depicted in the figures, spatially relative terms are also intended to cover different orientations of the device in use or operation. The device may be otherwise oriented (rotated 100 degrees or at other orientations) and the spatially relative descriptors used herein interpreted similarly.

As used herein, terms such as “first,” “second,” and “third” describe various elements, components, regions, layers and/or sections, but such elements, components, regions, layers and/or segments shall not be limited by such terms. These terms are only used to distinguish one element, component, region, layer or section from another element, component, region, layer or section. Terms such as “first,” “second,” and “third” when used herein do not imply a sequence or order unless the context clearly dictates otherwise.

Physical vapor deposition is a suitable and widely used process for forming a thin film on a substrate (ie, a wafer). Typically, an apparatus for performing physical vapor deposition operations includes a chamber and a process package. The chamber may include chamber walls and a pedestal, and a process kit may be placed within the chamber to avoid undesired material deposition on chamber components such as the chamber walls and pedestal.

Typically, the process kit includes a deposition ring, a cover ring, and a shield, but is not limited thereto. The deposition ring is placed on the base. The cover ring is disposed to surround the deposition ring and the base, and may at least partially cover the deposition ring. The wafer can be positioned on the susceptor, and an edge of the wafer can overlap at least a portion of the deposition ring. The barrier forms an enclosed space between the cover ring and the chamber wall. During the physical vapor deposition process of forming a film layer on the wafer (such as but not limited to), electrical arcing problems may occur. The arc may be caused by the electric breakdown of gas due to an excessively strong electric field and the continuous formation of plasma. The reason for the excessive electric field is that the charge accumulation exceeds a critical value. It should be noted here that the critical value will vary depending on the target impedance or the distance between process kits. For example, compared to common metal materials (such as titanium (Ti) or aluminum (Al)), cobalt materials have greater resistance. During the PVD process, their charge accumulation is also relatively large, which makes it easy to occur. Arc phenomenon. Generally speaking, arcing usually occurs at the interface between the cover ring and the barrier. The arc generated during physical vapor deposition may cause thicker deposits or undesirable contaminant residues on the wafer in areas containing the target film. For example, undesirable locally thicker layers can form above the wafer edge.

In some comparative embodiments, an additional cleaning operation may be performed to remove residues that serve as potential arc sources prior to the physical vapor deposition operation. This approach reduces arcing problems but reduces overall throughput and increases process costs. In other comparative examples, extending the exhaust time during the physical vapor deposition operation or increasing the exhaust temperature during the physical vapor deposition operation mitigates arcing problems, but reduces physical vapor deposition operation throughput and increases energy consumption. In other comparative examples, the discharge power is reduced to reduce charge accumulation, but this approach reduces physical vapor deposition throughput. In summary, although device designers have attempted to prevent arcing problems during physical vapor deposition operations by making the modifications described above, these methods have not been able to do so without increasing process time, energy consumption, and cost, or without reducing overall throughput. Effectively reduce arcing.

Therefore, the present disclosure provides a physical vapor deposition apparatus for mitigating arc problems without reducing physical vapor deposition throughput, increasing process costs, or increasing energy consumption. In some embodiments, by adjusting the distance between the cover ring and the barrier in the physical vapor deposition apparatus, the electron density distribution can be changed, thereby reducing the electric field strength to avoid arcing.

Figure 1 illustrates a schematic diagram of a physical vapor deposition apparatus 100 according to certain embodiments of the present disclosure. It should be understood that although an apparatus is illustrated as having components specific to a physical vapor deposition process, aspects of the disclosed apparatus are applicable to any type of processing operation utilizing plasma. For example, the disclosed aspects may be applied to a plasma-assisted chemical vapor deposition (PECVD) operation or a plasma etching operation.

As shown in FIG. 1 , physical vapor deposition apparatus 100 includes chamber walls 102 . In some embodiments, the chamber wall 102 may be a vacuum-sealed stainless steel chamber body, and a chamber 104 (or processing area) is formed within the chamber wall 102 . The physical vapor deposition apparatus 100 also includes a base 110, a cover ring 120, and a barrier 130. Specifically, the base 110 (also called a wafer stage or a substrate support) is disposed at the bottom of the chamber 104 . The base 110 is used to support and accommodate an object to be processed, such as a wafer. In some embodiments, the base 110 may include a heater (not shown) and/or an electrostatic chuck (ESC) (not shown).

As shown in FIG. 1 , the cover ring 120 surrounds the base 110 and is electrically insulated from the base 110 . In some embodiments, cover ring 120 includes aluminum, stainless steel, or copper. In some embodiments, cover ring 120 holds the wafer in place on susceptor 110 when a positive air pressure is applied between the heater and susceptor 110 so that heat can be efficiently conducted from the heater to the wafer. . In some embodiments, the cover ring 120 includes a recess 122 that is recessed from the lower surface of the cover ring 120 toward the upper surface of the cover ring 120 . Therefore, another function of the cover ring 120 is to allow a process gas flow (eg, argon gas) to flow from below the base 110 into the chamber 104 . In one embodiment, the base angle 124 of the notch 122 is not a right angle. In some embodiments, the bottom corner 124 of the notch 122 may be chamfered. Generally speaking, chamfering is a process that softens the corners of objects with sharp edges or edges. A common method is to process a right-angled edge into a surface with an angle of about 45 degrees. In other alternative embodiments, the bottom corner 124 of the recess 122 may be machined to form a face with other angles (eg, about 30 degrees to about 60 degrees). When the bottom corner 124 of the notch 122 is machined to form a chamfer, the bottom surface of the notch 122 will shrink. In detail, the portion of the notch 122 adjacent to the opening has a first width W1, and the portion far from the opening has a second width W2, and the first width W1 is greater than the second width W2.

In some embodiments, the physical vapor deposition apparatus 100 further includes a deposition ring 150 located between the base 110 and the cover ring 120 . In some embodiments, as shown in FIG. 1 , a deposition ring 150 is located on the base 110 and surrounds the periphery of the base 110 . Deposition ring 150 may be at least partially covered by cover ring 120 . In some embodiments, deposition ring 150 includes an insulating material such as aluminum oxide ( _AlXOY ) or aluminum nitride ( _{AlXNY )} , but _is not limited thereto. The deposition ring 150 is used to electrically insulate the base 110 and the cover ring 120 .

As shown in Figure 1, barrier 130 surrounds chamber wall 102 of physical vapor deposition apparatus 100. Specifically, barrier 130 is disposed between cover ring 120 and chamber wall 102 to form chamber 104 . Barrier 130 helps prevent or minimize deposition of particles sputtered from the target on the interior surface of chamber wall 102 . In some embodiments, barrier 130 includes aluminum, stainless steel, or copper.

As shown in FIG. 1 , barrier 130 may include a first vertical portion 132 , a second vertical portion 134 , a horizontal portion 136 , and an attachment portion 138 . In more detail, the cover ring 120 is located between the first vertical portion 132 and the base 110 . In some embodiments, attachment portion 138 is mounted to the top of chamber wall 102 . The first vertical portion 132 extends downwardly from the attachment portion 138 and is substantially parallel to the chamber wall 102 . The horizontal portion 136 is connected to the bottom end of the first vertical portion 132 and extends inwardly. In some embodiments, the angle between the horizontal portion 136 and the first vertical portion 132 is substantially a right angle. The second vertical portion 134 is connected to one end of the horizontal portion 136 and extends upward. Two ends of the horizontal part 136 are respectively connected to the bottom end of the first vertical part 132 and the bottom end of the second vertical part 134 and are located below the cover ring 120 . In some embodiments, the second vertical portion 134 is substantially parallel to the first vertical portion 132 . In some embodiments, second vertical portion 134 is smaller than first vertical portion 132 . In one embodiment, the first vertical portion 132, the second vertical portion 134, the horizontal portion 136, and the attachment portion 138 of the barrier 130 may be integrally formed. In another embodiment, the first vertical portion 132, the second vertical portion 134, the horizontal portion 136, and the attachment portion 138 of the barrier 130 may be assembled by welding.

Figure 2A illustrates a three-dimensional schematic view of the barrier 130 and the cover ring 120 according to certain embodiments of the present disclosure. Figure 2B shows a schematic cross-sectional view along section line A-A’ of Figure 2A. Figure 2C shows a partial enlarged view of area R in Figure 2B. You can refer to Figure 1, Figure 2A, Figure 2B and Figure 2C at the same time. It should be noted that the first vertical portion 132 is spaced apart from the outer side wall of the cover ring 120 by a first distance D1, and the first distance D1 is between about 2.3 mm and about 2.7 mm. In some embodiments, the first distance D1 may be between about 2.4 mm and about 2.6 mm, between about 2.4 mm and about 2.5 mm, or between about 2.5 mm and about 2.6 mm.

Figure 2D, Figure 2E and Figure 2F are diagrams illustrating the distribution relationship between the first distance and the charge according to various embodiments of the present disclosure. Figure 2D illustrates the charge distribution when the first distance D1 is between about 2.3 mm and about 2.7 mm. It can be seen from Figure 2D that when the first distance D1 is between about 2.3 millimeters and about 2.7 millimeters, the charges are uniformly distributed. Figure 2E illustrates the charge distribution when the first distance D1 is less than approximately 2.3 mm. It can be seen from FIG. 2E that when the first distance D1 is less than about 2.3 mm, most of the charges will be concentrated and accumulated between the first vertical portion 132 and the outer wall of the cover ring 120 , causing arcing to occur. Figure 2F illustrates the charge distribution when the first distance D1 is greater than approximately 2.7 mm. It can be seen from Figure 2F that when the first distance D1 is greater than about 2.7 mm, the charge is relatively loosely distributed between the first vertical portion 132 and the outer wall of the cover ring 120, making it difficult for plasma to be generated or requiring increased application. power to produce the required amount of plasma. Accordingly, if the first distance D1 is too large or too small, it will affect the uniformity of charge distribution or the intensity of the electric field, resulting in insufficient plasma or causing arc generation.

Continue to Figure 1, Figure 2A, Figure 2B and Figure 2C. The second vertical portion 134 is located below the cover ring 120 . In some embodiments, the top end of the second vertical portion 134 extends into the recess 122 of the cover ring 120 and substantially contacts the bottom surface of the recess 122 . It should be noted that although the top end of the second vertical portion 134 substantially contacts the bottom surface of the recess 122 , it does not block the flow of process gas (eg, argon gas) into the chamber 104 . During the physical vapor deposition process, high-energy particles (ions) collide with each other at high speed in the chamber, and may hit the process kits (eg, barrier 130) in the chamber, causing a slight displacement in the distance between the process kits. By processing the bottom corner 124 of the notch 122 of the cover ring 120 into a chamfer, the degree of displacement of the second vertical portion 134 of the barrier 130 during the physical vapor deposition process is further limited, thereby controlling the first distance D1 Between about 2.3 mm and about 2.7 mm. In one embodiment, the bottom surface of the notch 122 has a second width W2, the second vertical portion has a third width W3, and the second width W2 is substantially greater than or equal to the third width W3. In more detail, the second width W2 is greater than the third width W3 by about 0.1 mm to about 0.4 mm, such as about 0.2 mm to about 0.3 mm.

Figure 2G illustrates a partial enlarged view of the region R in Figure 2B according to another embodiment of the present disclosure. In some embodiments, the top end of the second vertical portion 134 extends into the recess 122 of the cover ring 120 and does not contact the bottom surface of the recess 122 .

Please return to FIG. 1 . In some embodiments, the physical vapor deposition apparatus 100 may further include an annular grounding ring 140 surrounding the support column 112 and installed on the base 110 . Specifically, the diameter of the grounding ring 140 is larger than the diameter of the bearing platform of the base 110 . In more detail, the grounding ring 140 extends laterally below the horizontal portion 136 of the barrier 130 . In some embodiments, support posts 112 include aluminum, stainless steel, or copper. In some embodiments, ground coil 140 includes aluminum, stainless steel, or copper. The ground ring 140 can lead away excess charges accumulated on the base 110 .

In some embodiments, the physical vapor deposition apparatus 100 further includes a target 160 and a power supply 170 . The power supply 170 can be electrically connected to the target 160 . In some embodiments, the power supply 170 is a direct current (DC) supply, a radio frequency (RF) supply, or a direct current-radio frequency (DC-RF) supply. Target 160 contains the material to be deposited onto the wafer. In various embodiments, the target 160 may include copper (Cu), titanium (Ti), nickel (Ni), aluminum (Al), cobalt (Co), tungsten (W), tantalum (Ta), silver (Ag) ), gold (Au), nickel-platinum alloy (Ni-Pt), nickel-titanium alloy (Ni-Ti) or other suitable metals or metal alloys. The power supply 170 can apply a bias voltage to the target 160, and the electric field generated in the chamber 104 by the applied voltage excites the sputtering gas to form a plasma. The plasma actively impacts and bombards the target 160 to remove particles from the target. Material 160 is sputtered and deposited onto the wafer.

In some embodiments, physical vapor deposition apparatus 100 also includes one or more pumps 180 to exhaust gas from chamber 104 . In various embodiments, pump 180 may be controlled by a controller (not shown) and may be used to maintain the pressure in chamber 104 at a desired pressure value. In addition, after the processing process is completed, the pump 180 may be used to remove gases from the chamber 104 in preparation for removing the wafer from the chamber 104 . In various embodiments, pump 180 may include a cryopump, a turbomolecular pump, a mechanical pump, or other suitable pumps.

In some embodiments, physical vapor deposition apparatus 100 further includes gas channels 190 . The gas channel 190 has a gas flow control valve (not shown) such as a mass flow controller to allow the process gas to pass through at a set flow rate. The process gas may include an inert gas such as argon (Ar) or xenon (Xe) that is capable of striking target 160 and sputtering material from target 160 . Figure 1 only shows one gas channel 190, but it is not limited thereto. The number of gas channels 190 can be increased according to the demand, for example, 2, 3 or 4.

In some embodiments, the physical vapor deposition apparatus 100 further includes an arc detection element 210 . The arc detection element 210 is connected to the chamber 104 and transmits signals to the arc detection element 210 through a sensing element (not shown) disposed in the chamber 104 . In some embodiments, the arc detection component 210 includes a magnetic field sensor (not shown) and an arc analysis circuit system (not shown). Magnetic field sensors may include coils made of conductive materials such as copper, aluminum, nickel, or other metals or alloys. In some embodiments, the coil is a closed conductive path. The magnetic field sensor is configured to generate a magnetic field signal, for example in the form of a current or a voltage, where the magnitude of the magnetic field signal is proportional to the magnetic flux through a closed conductive path of the magnetic field sensor. The arc analysis circuitry is configured to evaluate the magnetic field signal and determine whether an arc has occurred within the chamber 104 . If an arc is detected, the wafer can be removed and evaluated for defects, and power supply 170 can be immediately shut down until chamber 104 can be tested and/or repaired.

In some embodiments, the physical vapor deposition apparatus 100 can be controlled and automated through a system controller (not shown). Generally speaking, the system controller includes a central processing unit (not shown), a support circuit (not shown) or a memory (not shown). The central processing unit can be any type of computer processor, which is used to control various system functions, wafer movement, supporting hardware (such as sensors, robotic arms, motors, etc.) and monitoring processes (such as base temperature, Power supply variables, process time, support circuit signals, etc.). The memory is connected to the central processing unit and is an easily accessible memory, such as Random Access Memory (RAM), Read-Only Memory (ROM), hard disk, floppy disk or any Other local or remote digital storage. Software instructions and data can be encoded and stored in memory to instruct the central processing unit. Support circuit connection to central processing unit. Support circuits include power supplies, clock circuits, output/input circuits, cache memories, subsystems, etc.

FIG. 3 is a schematic diagram of a physical vapor deposition apparatus 100 during a process according to certain embodiments of the present disclosure. During the physical vapor deposition process, the support column 112 will raise the base 110 and the ground ring 140 to an operating height. At this time, the ground ring 140 will touch the barrier 130, thereby making the overall charge loop appear uniform. Grounding state. At the same time, the deposition ring 150 will also touch the cover ring 120 , and the deposition ring 150 is used to electrically insulate the base 110 and the cover ring 120 . On the other hand, the process gas (such as argon (Ar) or xenon (Xe)) flows from below the base 110 through the gas channel 190 through the recess 122 of the cover ring 120 and passes through the first vertical portion 132 and the outside of the cover ring 120 A first distance D1 between the walls and upward into the chamber 104, as indicated by the direction of the arrow in Figure 3. Since the process gas will flow through the channel or gap (ie, the first distance D1 ) between the first vertical portion 132 and the outer wall of the cover ring 120 , the flow rate of the process gas will affect the formation of plasma and/or the arc. produce. In some embodiments, the flow rate of the process gas through the channel or void (ie, the first distance D1 ) may range from about 400 sccm to about 450 sccm. For example, the flow rate of the process gas flowing through the channel or gap (ie, the first distance D1 ) may be in the range of about 410 sccm to about 440 sccm or may be in the range of about 420 sccm to about 430 sccm. When the flow rate of the process gas is less than about 400 sccm, the amount of process gas entering the chamber 104 is insufficient, thereby affecting the amount of plasma generated. On the contrary, when the flow rate of the process gas is greater than about 450 sccm, a large amount of charge is likely to accumulate between the first vertical portion 132 and the outer wall of the cover ring 120 (ie, the first distance D1) after the plasma is formed, and an arc is easily generated. .

FIG. 4 illustrates a flow chart of a method 30 of depositing a thin film according to certain embodiments of the present disclosure. Figures 5, 6, 7, and 8 illustrate schematic cross-sectional views at different stages of a method of depositing a thin film according to certain embodiments of the present disclosure. It is understood that additional operations may be performed before, during, and after method 30, and some of the operations may be replaced, eliminated, or moved for additional embodiments of method 30. The method 30 of depositing a cobalt film is only an exemplary embodiment, which includes operations 310 , 320 , 330 , 340 and 350 .

Referring to FIG. 5 , in operation 310 , a wafer 410 is received in a physical vapor deposition apparatus (such as the physical vapor deposition apparatus 100 described above). In some embodiments, the wafer 410 placed on the base 110 is raised to an operating position such that the deposition ring 150 contacts the cover ring 120 .

In operation 320 , a process gas is introduced through the gas channel 190 , and the process gas flows from below the base 110 through the recess 122 at the bottom of the cover ring 120 and passes through the barrier 130 (ie, the first vertical portion 132 ) and the cover ring 120 After passing through the passage between the outer side walls (ie, the first distance D1), it flows into the chamber 104, as shown in Figure 3.

Referring to FIG. 6 , in operation 330 , energy is delivered to the physical vapor deposition apparatus 100 to form a plasma 510 . Specifically, the energy is provided by the power supply 170, where the power supply 170 is a DC-RF power supply. In some embodiments, the pressure in chamber 104 can be adjusted to a desired pressure by pump 180 . A process gas (such as argon (Ar) or xenon (Xe)) is then introduced into the chamber 104 through the gas channel 190 until optimal conditions for igniting the plasma 510 are reached.

Referring to FIG. 7 , in operation 340 , the plasma 510 is caused to bombard the target 160 in the physical vapor deposition apparatus 100 . Specifically, the target 160 may be a cobalt target. In some embodiments, the power supply 170 may apply a bias voltage to the target 160 , thereby generating atoms, molecules, and/or ions from the target 160 . Ions in plasma 510 , such as Ar ions or Xe ions, accelerate and impact target 160 . It should be noted that compared with common metal materials (such as titanium (Ti) or aluminum (Al)), cobalt materials have greater resistance, and their charge accumulation during the PVD process is also relatively large, making it easy to Arcing occurs. Therefore, it is necessary to limit the first distance D1 between the first vertical portion 132 of the barrier 130 and the outer side wall of the cover ring 120 in the physical vapor deposition apparatus 100 (see FIG. 1 ).

Referring to Figure 8, in operation 350, a thin film 420 is deposited onto the surface of wafer 410. Specifically, the film 420 may be a cobalt film.

FIG. 9 illustrates a flowchart of a method 60 of forming a semiconductor structure according to certain embodiments of the present disclosure. FIGS. 10 , 11 , 12 , 13 , 14 , 15 and 16 illustrate schematic cross-sectional views at different stages of a method 60 for forming a semiconductor structure according to certain embodiments of the present disclosure. It is to be understood that additional operations may be performed before, during, and after method 60, and that some of the operations may be replaced, eliminated, or moved for additional embodiments of method 60. The method 60 of forming a semiconductor structure is only an exemplary embodiment, which includes operations 610 , 620 , 630 , 640 , 650 and 660 .

Referring to FIG. 10, in operation 610, a dielectric layer 720 is deposited on the underlying structure 710. In various embodiments, dielectric layer 720 includes one or more layers of dielectric materials, such as silicon oxide, silicon nitride, titanium nitride, other suitable dielectric materials, and/or combinations thereof. Examples of high-k dielectric materials include HfO ₂ , HfSiO, HfSiON, HfTaO, HfTiO, HfZrO, zirconium oxide, aluminum oxide, titanium oxide, hafnium dioxide-aluminum oxide (HfO ₂ -Al ₂ O ₃ ) alloy, and others Suitable high dielectric constant dielectric materials, and/or combinations thereof. In various embodiments, dielectric layer 720 may be formed by chemical vapor deposition (CVD), atomic layer deposition (ALD), or any suitable method.

In some embodiments, the underlying structure 710 is a typical semiconductor substrate with various preparatory metal layers deposited or separate dielectric layers formed thereon. For example, the underlying structure 710 may be a silicon substrate with active features, such as one or more polysilicon layers, a field isolation oxide layer, a gate oxide layer, a silicon nitride layer, and a metallization layer.

In some embodiments, to form underlying structure 710, an extremely pure single crystal silicon wafer is first exposed to high temperature vapor and a layer of silicon nitride is formed thereon. Then, reactive gases, such as brine and ammonia, are deposited on the surface of the silicon nitride layer by CVD. It is worth noting that other deposition steps such as atmospheric pressure CVD (APCVD), low pressure CVD (LPCVD), plasma enhanced CVD (PECVD), organic metal CVD (Metal Organic CVD, MOCVD), PVD, ALD, chemical solution deposition, sputtering, and combinations thereof can all be used. This structure is coated with a photoresist layer, and vias are etched through photolithographic patterning and dry etching processes to form a shallow trench isolation (STI) structure. The underlying structure 710 includes various structures and the layers in front of the metal layer are simplified as a single layer in FIGS. 10-16 .

Referring to FIG. 11 , in operation 620 , an opening 730 is formed through the dielectric layer 720 . In more detail, opening 730 exposes a portion of underlying structure 710 . In various embodiments, first, a photoresist layer (not shown) can be coated on the dielectric layer 720, and then the patterning process is completed through photolithography technology. During the patterning process, the photoresist layer can be selectively exposed to ultraviolet radiation and developed to form a pattern of holes in the photoresist mask (not shown). Openings 730 may then be formed through the dielectric layer 720 by dry etching using reactive gases such as fluoride, oxygen, chlorine, and boron trichloride. In other embodiments, nitrogen, argon, helium and other gases may sometimes be added to the reaction gas.

Referring to FIG. 12 , in operation 630 , a work function layer 740 is formed at the bottom of the opening 730 . Work function layer 740 is a single layer made of a conductive material, such as TiN, TaN, TaAlC, TiC, TaC, Co, Al, TiAl, HfTi, TiSi, TaSi, or TiAlC, or a multilayer of two or more of these materials. . For n-channel field-effect transistors (FETs), one or more of TaN, TaAlC, TiN, TiC, Co, TiAl, HfTi, TiSi, and TaSi are used as work function layer 740, and for p-channel FET, one or more of TiAlC, Al, TiAl, TaN, TaAlC, TiN, TiC, and Co are used as work function layer 740. The work function layer 740 can be formed by ALD, PVD, CVD, electron beam evaporation, or other suitable processes. Additionally, work function layer 740 may be formed separately for n-channel FETs and p-channel FETs, which may use different metal layers.

Referring to FIG. 13 , in operation 640 , a first cobalt thin film layer 750 is deposited in the opening 730 in a physical vapor deposition device (such as the above-mentioned physical vapor deposition device 100 ), and the first cobalt thin film layer 750 is located in the functional area. On the function layer 740. It should be noted that depositing the first cobalt thin film layer includes flowing a process gas through the gap between the barrier and the cover ring at a flow rate of between about 400 sccm and about 450 sccm.

Referring to FIG. 14 , in operation 650 , a second cobalt thin film layer 760 is formed to cover the first cobalt thin film layer 750 and a sidewall of the opening 730 . In some embodiments, the second cobalt thin film layer 760 is conformally deposited on the first cobalt thin film layer 750 and the sidewalls of the opening 730 by a CVD process.

Referring to FIG. 15 , in operation 660 , a third cobalt thin film layer 770 is formed to cover the second cobalt thin film layer 760 . In some embodiments, the third cobalt thin film layer 770 fills the remaining openings 730 by electrochemical plating (ECP).

In some embodiments, after operation 660, the metal gate 810 may be formed by planarizing the second cobalt film layer 760 and the third cobalt film layer 770, as shown in FIG. 16. Since the materials of the first cobalt thin film layer 750 , the second cobalt thin film layer 760 and the third cobalt thin film layer 770 are all cobalt, there is actually no obvious interface in the metal gate 810 as shown in FIG. 16 . For example, a chemical-mechanical planarization (CMP) process may be used to planarize the top surface of the metal gate 810 and the top surface of the dielectric layer 720 .

One aspect of the present disclosure provides a physical vapor deposition device including a chamber, a base, a cover ring, and a barrier. The base is arranged at the bottom of the chamber. The cover ring surrounds the base and is electrically insulated from the base. The barrier surrounds the chamber walls of the physical vapor deposition apparatus. The barrier includes a first vertical portion, a second vertical portion, and a horizontal portion. The first vertical portion is substantially parallel to the chamber wall of the physical vapor deposition device, and the cover ring is located between the first vertical portion and the base, wherein the first vertical portion is spaced a first distance from the outer sidewall of the cover ring, and the first The distance is between 2.3 mm and 2.7 mm. The second vertical portion is located below the cover ring, wherein a top end of the second vertical portion substantially contacts the cover ring. The horizontal portion is located below the cover ring and connects the first bottom end of the first vertical portion and the second bottom end of the second vertical portion.

According to various embodiments of the present disclosure, the physical vapor deposition apparatus further includes a deposition ring located between the base and the cover ring, and the deposition ring is configured to electrically insulate the base and the cover ring. According to various embodiments of the present disclosure, the cover ring has a recess, which is recessed from the lower surface of the cover ring toward the upper surface of the cover ring. According to various embodiments of the present disclosure, a bottom corner of the recess is chamfered. According to various embodiments of the present disclosure, a top end of the second vertical portion extends into the recess. According to various embodiments of the present disclosure, the bottom surface of the notch has a first width, the second vertical portion has a second width, and the first width is substantially greater than or equal to the second width. According to various embodiments of the present disclosure, the physical vapor deposition device further includes a grounding ring surrounding the support column of the base, and the diameter of the grounding ring is larger than the diameter of the bearing platform of the base. According to various embodiments of the present disclosure, the grounding ring extends laterally below the horizontal portion.

Another aspect of the present disclosure is to provide a method for depositing a thin film, including the following operations. A wafer is received in a physical vapor deposition apparatus. The process gas is introduced through the gas channel, and the process gas flows from the bottom of the base through the recess of the cover ring and through a channel between the barrier and the outer side wall of the cover ring, and flows upward into the chamber. Energy is delivered into the chamber to form a plasma from the process gas, wherein the energy is provided by a radio frequency source and a direct current source. The plasma is bombarded with the target material in the physical vapor deposition device. Deposit a thin film onto the surface of the wafer.

Another aspect of the present disclosure is to provide a method of forming a semiconductor structure, including the following operations. Deposit a dielectric layer on the underlying structure. An opening is formed through the dielectric layer. A work function layer is formed in the opening. Depositing a first cobalt thin film layer in the opening in a physical vapor deposition device, and the first cobalt thin film layer is located on the work function layer, wherein depositing the first cobalt thin film layer includes allowing a process gas to flow through the gap between the barrier and the cover ring The flow rate is between approximately 400 sccm and approximately 450 sccm. A second cobalt thin film layer is formed to cover the first cobalt thin film layer and the sidewall of the opening. A third cobalt film is formed to cover the second cobalt film layer.

The foregoing text summarizes the features of many embodiments so that those with ordinary knowledge in the art can better understand the various embodiments of the present disclosure from various aspects. It should be understood by those with ordinary skill in the art that other processes and structures can be easily designed or modified based on the various embodiments of the present disclosure to achieve the same purpose and/or achieve the same goals as those introduced here. Embodiments have the same advantages. Those of ordinary skill in the art should also understand that these equivalent structures do not depart from the spirit and scope of the invention of various embodiments of the present disclosure. Various changes, substitutions or modifications may be made to the various embodiments of the present disclosure without departing from the spirit and scope of the present disclosure.

100:Physical vapor deposition device 102: Chamber wall 104: Chamber 110:Pedestal 112:Support column 120: cover ring 122: Notch 124: Bottom corner 130:Barrier 132: First vertical section 134: Second vertical part 136: Horizontal part 138: Attachment part 140:Ground circle 150: Sedimentation Ring 160:Target 170:Power supply 180:Pump 190:Gas channel 210: Arc detection element 30:Method 310: Operation 320: Operation 330: Operation 340: Operation 350: Operation 410:wafer 420:Thin film 510:Plasma 60:Method 610: Operation 620: Operation 630: Operation 640: Operation 650:Operation 660: Operation 710:Infrastructure 720: Dielectric layer 730:Open your mouth 740: Work function layer 750: First cobalt film layer 760: Second cobalt film layer 770: The third cobalt film layer 810: Metal gate A-A’: section line D1: first distance R:Region W1: first width W2: second width W3: third width

The detailed description of embodiments of the present disclosure will be fully understood when read in conjunction with the accompanying drawings. It should be noted that, in accordance with standard industry practice, features are not drawn to scale and are for illustration purposes only. In fact, the dimensions of various features may be arbitrarily increased or reduced for clarity of discussion. The same reference numbers are used in the description and drawings to represent similar features. Figure 1 is a schematic diagram of a physical vapor deposition apparatus according to certain embodiments of the present disclosure. Figure 2A is a schematic three-dimensional view of a barrier and a cover ring according to certain embodiments of the present disclosure. Figure 2B shows a schematic cross-sectional view along section line A-A’ of Figure 2A. Figure 2C shows a partial enlarged view of area R in Figure 2B. Figure 2D, Figure 2E and Figure 2F are diagrams illustrating the distribution relationship between the first distance and the charge according to various embodiments of the present disclosure. Figure 2G illustrates a partial enlarged view of the region R in Figure 2B according to another embodiment of the present disclosure. Figure 3 is a schematic diagram of a physical vapor deposition apparatus during a process according to certain embodiments of the present disclosure. FIG. 4 illustrates a flow chart of a method of depositing a thin film according to certain embodiments of the present disclosure. Figures 5, 6, 7 and 8 illustrate schematic cross-sectional views at different stages of a method of depositing a thin film according to certain embodiments of the present disclosure. FIG. 9 illustrates a flowchart of a method of forming a semiconductor structure according to certain embodiments of the present disclosure. 10 , 11 , 12 , 13 , 14 , 15 and 16 are schematic cross-sectional views at different stages of a method of forming a semiconductor structure according to certain embodiments of the present disclosure.

100:Physical vapor deposition device

102: Chamber wall

104: Chamber

110:Pedestal

112:Support column

120: cover ring

122: Notch

124: Bottom corner

130:Barrier

132: First vertical section

134: Second vertical part

136: Horizontal part

138: Attachment part

140:Ground circle

150: Sedimentation Ring

160:Target

170:Power supply

180:Pump

190:Gas channel

210: Arc detection component

D1: first distance

W1: first width

W2: second width

W3: third width

Claims (10)

A physical vapor deposition device, including: a chamber; a base arranged at a bottom in the chamber; a target material arranged in the chamber, wherein the target material is a cobalt target material; and a cover ring surrounding the base is electrically insulated from the base; and a barrier surrounds a chamber wall of the physical vapor deposition device, the barrier including: a first vertical portion connected to the chamber of the physical vapor deposition device The walls are substantially parallel, and the cover ring is located between the first vertical portion and the base, wherein the first vertical portion is spaced a first distance from an outer wall of the cover ring, and the first distance is between about 2.3 millimeters. to about 2.7 mm, and a flow rate of a process gas flowing through the first distance is in the range of about 400 sccm to about 450 sccm, the first distance and the flow rate are configured such that the resistance of the cobalt causes easy accumulation of The charge presents a uniform distribution; a second vertical portion is located below the cover ring, and a top end of the second vertical portion substantially contacts the cover ring; and a horizontal portion is located below the cover ring and connected to the first vertical portion a first bottom end of the second vertical portion and a second bottom end of the second vertical portion. The physical vapor deposition apparatus of claim 1, further comprising a deposition ring located between the base and the cover ring, the deposition ring being configured to electrically insulate the base and the cover ring. The physical vapor deposition device of claim 1, wherein the cover ring has a recess, which is recessed from a lower surface of the cover ring toward an upper surface of the cover ring. The physical vapor deposition device as claimed in claim 3, wherein a bottom corner of the notch is chamfered. The physical vapor deposition device of claim 3, wherein the top end of the second vertical portion extends into the notch. The physical vapor deposition device of claim 3, wherein a bottom surface of the notch has a first width, the second vertical portion has a second width, and the first width is substantially greater than or equal to the second width. Width. The physical vapor deposition device of claim 1 further includes a grounding ring surrounding a support column of the base, and a diameter of the grounding ring is larger than a diameter of a bearing platform of the base. The physical vapor deposition device of claim 7, wherein the grounding ring extends laterally below the horizontal part. A method of depositing a thin film, including: receiving a wafer in a physical vapor deposition device, wherein the physical vapor deposition device includes a target material, and the target material is a cobalt target material; A process gas is introduced through a gas channel, and the process gas flows from below a base through a recess of a cover ring and through a channel between a barrier and an outer wall of the cover ring, and flows upward into a cavity Chamber, wherein a flow rate of the process gas flowing through the channel is in the range of about 400 sccm to about 450 sccm, and a distance of the channel between the barrier and the outer side wall of the cover ring is from about 2.3 mm to About 2.7 mm, this distance is configured to uniformly distribute the charge that is easily accumulated due to the resistance of the cobalt; deliver an energy to the chamber to cause the process gas to form a plasma, wherein the energy is provided by a direct current - Provided by an RF supplier; causing the plasma to bombard the target in the physical vapor deposition device; and depositing a cobalt film onto a surface of the wafer. A method of forming a semiconductor structure, including: depositing a dielectric layer on a lower structure; forming an opening penetrating the dielectric layer; forming a work function layer in the opening; depositing a The first cobalt thin film layer is in the opening, and the first cobalt thin film layer is located on the work function layer, wherein depositing the first cobalt thin film layer includes: flowing a process gas through a barrier and an outer side wall of a cover ring a flow rate of a gap between about 400 sccm and about 450 sccm, and a distance of the gap between about 2.3 mm and about 2.7 mm; delivering energy to the physical vapor deposition device to cause the process gas to form a plasma ;and Make the plasma bombard a target in the physical vapor deposition device, wherein the target is a cobalt target; form a second cobalt thin film layer covering the first cobalt thin film layer and a side wall of the opening; and form A third cobalt thin film layer covers the second cobalt thin film layer; wherein the distance is configured so that charges that are easily accumulated due to the resistance of the cobalt present a uniform distribution.

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