TWI624567B - Electrofill vacuum plating cell - Google Patents

Abstract

The disclosed embodiments relate to methods and equipment for immersing a substrate in an electrolyte in a plating bath under a sub-atmospheric state to reduce or eliminate bubble formation or entrapment when the substrate is immersed. Various electrolyte recycling circuits are exposed to provide electrolyte to the plating tank. The recirculation loop may include pumps, degassers, sensors, valves, and the like. The disclosed embodiments allow rapid immersion of the substrate, thereby greatly reducing issues related to bubble formation and uneven plating time during plating.

Description

Vacuum plating tank

This application claims the priority of US Patent Provisional Application No. 61 / 735,971 filed on December 11, 2012. The name of this US patent provisional application is "ELECTROFILL VACUUM PLATING CELL". This application also claims Priority of US Patent Provisional Application No. 61 / 773,725, filed on March 6, 2013, the name of this US Patent Provisional Application is "ELECTROFILL VACUUM PLATING CELL", the content of which is hereby incorporated by reference as a whole. Part of the content and for all purposes. This application is also a part of US Patent Application Nos. 12 / 684,787 and 12 / 684,792 filed on January 8, 2010. The patent names are "APPARATUS FOR WETTING PRETREATMENT FOR ENHANCED DAMASCENE METAL "FILLING" and "WETTING PRETREATMENT FOR ENHANCED DAMASCENE METAL FILLING", the contents of which are hereby incorporated by reference as a part of the disclosure of this case and for all purposes.

The present invention relates to a method and apparatus for electroplating a metal onto a substrate surface.

For various reasons, the wafer to be plated can be tilted to a non-horizontal angle when immersed in a plating bath. Therefore, relative to the total time it takes to fill features on the substrate (eg, current technology node wafer structures can be filled in about 1-2s, in some cases less than 500ms), some existing methods for electroplating And the equipment requires that the substrate needs to be immersed in the plating solution for a relatively long period of time (for example: 120-200ms between the time when the leading edge enters the solution and the time when the trailing edge is completely immersed). Because the leading edge of the substrate enters the plating solution and plating begins before the trailing edge of the substrate, a relatively long immersion time (defined as the time it takes for the entire plating surface of the substrate to be immersed in the plating solution) will cause inconsistent feature filling . Initial plating inhomogeneities may Persistent during the plating process, resulting in uneven filling. As the industry moves from 300mm to 450mm wafers, these effects will be worsened. The expectation is not limited to any particular theory or mechanism of action. The difference in the start time of plating of the entire wafer may lead to uneven adsorption of additives such as accelerators, inhibitors, and leveling agents, which may cause unevenness of the entire wafer surface Uniform plating. Therefore, it is substantially better to have a shorter immersion time relative to the time it takes to fill the smaller features, so that the difference in fill start time of the entire wafer can have the smallest impact, so that the filling of the features and the plating Uniformity can be maximized.

The cost of minimizing the immersion time is that bubbles will form at the interface between the plating solution and the substrate. During the immersion of the wafer into the plating electrolyte, bubbles may be trapped below the plated side (active side or plated side) of the wafer. If the substrate is dipped too quickly, the problem of air bubble trapping may worsen. Air bubbles trapped on the plated side of the wafer can cause problems. Where the bubbles appear, the bubbles will cover the plated surface of the wafer and prevent the plated surface of the wafer from contacting the electrolyte, thereby creating areas where plating cannot occur. According to the time when the bubbles start to be trapped on the wafer and the length of time that the bubbles remain trapped on the wafer, the resulting plating defects can be manifested as areas without plating or areas with reduced coating thickness. Therefore, under the current plating method, if the immersion time is too fast, significant plating defects may occur.

The embodiments herein relate to methods and equipment for plating materials onto substrates. In the disclosed embodiment, the substrate is immersed in the electrolyte at a low pressure to reduce or eliminate the risk of air bubbles trapping under the substrate when immersed in the substrate. In an embodiment of the disclosed embodiment, a method for electroplating a metal onto a substrate is provided. The method includes flowing an electrolyte through a plating recirculation circuit, the electroplating recirculation circuit including an electrolyte storage tank, a pump, and the like. A plating tank and a degasser for degassing the electrolyte before being introduced into the plating tank; the substrate is immersed in the electrolyte in the plating tank, wherein the pressure in the plating tank during the immersion is Below about 100 Torr; plating the material onto a substrate; and removing the substrate from the electrolyte.

In some embodiments, the pressure in the plating bath during immersion is at least about 20 Torr. The step of immersing the substrate in the electrolyte may occur during a period of about 255 ms or less, where the substrate has a diameter of about 150 mm or more. In some cases, the immersion duration may be shorter. For example: the step of immersing the substrate in the electrolyte may take about 50ms In the following periods, the substrate has a diameter of about 150 mm or more. In these or other embodiments, the step of immersing the substrate in the electrolyte occurs during a period having a first duration, and the step of plating the material to fill a feature on the substrate occurs during a period having a second duration , Where the first duration is less than about 10% of the second duration. In some cases, as measured by volume, the feature is the smallest feature on the substrate. If measured by volume, the feature may also be a feature with a medium size on the substrate.

The substrate can be immersed at an angle, and in some embodiments, the substrate is swung in a horizontal direction at a swing speed of about 0.25-10 degrees / second. The low pressure in the plating bath will exist at least during the immersion period and may last for a long time. In some embodiments, the pressure in the plating tank is maintained at about 100 Torr or less during about 10 ms from the beginning of the plating. In some examples, the pressure in the plating tank is maintained at about 100 Torr or less until after the plating is stopped. Load lock chambers may be used in some embodiments. In this case, the method may further include: inserting the substrate into the load lock chamber and reducing the pressure in the load lock chamber to below about 100 Torr.

The method may further include a step of injecting a gas into the electrolytic solution after the electrolytic solution is degassed and before the electrolytic solution is introduced into the plating tank. The injected gas may be oxygen. Oxygen can be injected to an electrolyte concentration of less than about 10 ppm. In some cases, oxygen can be injected to an electrolyte concentration below about 1 ppm.

In some embodiments, the method further comprises: flowing the electrolyte through a gas-controlled recirculation loop, the gas-controlled recirculation loop comprising: an electrolyte storage tank, and a dissolved gas sensor, wherein the dissolved gas controller The input of the controller controls the gas injection unit to adjust the concentration of dissolved gas in the electrolyte. The electroplating recirculation circuit can be separated from the gas control recirculation circuit. In some embodiments, the electrolyte can bypass the electrolyte storage tank of the electroplating recirculation loop by passing the bypass conduit during electroplating. When electroplating does not occur, the electrolyte can also flow through an atmospheric pressure recirculation circuit, wherein the atmospheric pressure recirculation circuit includes an electrolyte storage tank, an atmospheric pressure electrolyte storage tank, and an atmospheric pressure circuit pump. The method may also include: degassing the electrolyte in a degassed electrolyte storage tank; and flowing the electrolyte through a degassing recirculation circuit and an atmospheric pressure recirculation circuit, wherein the degassing recirculation circuit includes: An air circuit pump and a degassed electrolyte storage tank, wherein the atmospheric pressure recirculation circuit includes: a degassed electrolyte storage tank, an atmospheric pressure circuit pump, and an atmospheric pressure electrolyte storage tank.

In another aspect of the disclosed embodiment, an apparatus for electroplating metal onto a substrate is provided. The apparatus includes: a plating tank configured to withstand a pressure of about 100 Torr or less, and the plating tank includes: a A substrate holder, an electrolyte storage tank, and a substrate positioning system capable of controlling the direction of the substrate when the substrate is immersed in the electrolyte storage tank; a plating recirculation circuit includes: an electrolyte storage tank, a pump, A degasser, and a plating tank, wherein the degasser is disposed after the electrolyte storage tank and in front of the plating tank in the plating recycling circuit; and a plating controller for use during the plating process and when the substrate is When immersed in the electrolyte storage tank, the pressure was maintained below about 100 Torr.

In some embodiments, the substrate positioning system can control the movement, tilt, and rotation of the substrate. The device may also include a dissolved gas sensor. In some cases, the dissolved gas controller may be used in combination with a dissolved gas sensor and a gas injector, where the dissolved gas controller controls the gas injector based on the measurement results from the dissolved gas sensor.

The bypass conduit can be used in some embodiments, where the plating controller is used to flow the electrolyte through the bypass conduit during plating, thereby bypassing the electrolyte storage tank. In some embodiments, an atmospheric pressure recirculation circuit may be used. The atmospheric recirculation circuit includes an electrolyte storage tank, an atmospheric pressure circuit pump, and an atmospheric pressure electrolyte storage tank, wherein the electroplating controller is used to avoid the atmospheric recirculation circuit. Circulate during plating. In some embodiments, the device may include a degassed electrolyte recycling circuit and an atmospheric pressure recycling circuit, wherein the degassed electrolyte recycling circuit includes: an electrolyte storage tank, a degassing circuit pump, and A degassed electrolyte storage tank, and the atmospheric recirculation circuit includes: a degassed electrolyte storage tank, an atmospheric circuit pump, and an atmospheric pressure electrolyte storage tank, wherein the plating controller is used to ensure the degassed electrolyte recycling circuit It will not circulate during plating. In various cases, the apparatus includes more than one additional plating tank configured to operate below about 100 Torr, wherein the additional plating tanks are in fluid communication with the electrolyte storage tank.

These and other features are described below with reference to the associated drawings.

101‧‧‧Plating System

103 / 322‧‧‧ Wafer

104‧‧‧Clamp

105‧‧‧ liquid tank

107‧‧‧ Electrolyte

109‧‧‧ Bubble

112‧‧‧immersion situation

301 / 601‧‧‧plating tank

304‧‧‧ storage tank

306/606/706/806/824/906/916 / 926‧‧‧Pump

308‧‧‧Degasser

302‧‧‧Recirculation circuit

310‧‧‧Vacuum pump

312‧‧‧Gas control circuit

314‧‧‧Dissolved gas sensor

318‧‧‧pressure sensor

323‧‧‧Anode

350‧‧‧ Controller

355‧‧‧Gas injection unit

402‧‧‧wafer lifting assembly

404‧‧‧wafer tilt assembly

406‧‧‧Wafer Rotation Assembly

410‧‧‧slot

408‧‧‧Vacuum top plate

422‧‧‧ cone

424‧‧‧Clamp

500‧‧‧plating equipment

510‧‧‧washing device

512‧‧‧Nozzle arm actuator

513‧‧‧nozzle arm

514‧‧‧Nozzle

522‧‧‧lip seal

524‧‧‧ cup body

525‧‧‧bottom

526‧‧‧ cone

528‧‧‧cup post

530‧‧‧plating tank

532‧‧‧volume

533‧‧‧Top hat

534‧‧‧fluid

535‧‧‧level

560‧‧‧Recycling Mask

570‧‧‧Flushing Mask

602‧‧‧plating fluid circuit

604‧‧‧Plating fluid storage tank

608/708/808 / 908‧‧‧ Deaerator

610‧‧‧vacuum pump

612‧‧‧fluid sensing circuit

614‧‧‧Dissolved gas sensor

618‧‧‧pressure sensor

616‧‧‧ pre-humidifier

701/801 / 901‧‧‧vacuum plating tank

702‧‧‧plating circuit

704‧‧‧Plating bath

720‧‧‧fluid circuit

722/822/922 / 923‧‧‧ Valve

804 / 904‧‧‧Vacuum plating bath

825 / 940‧‧‧ Atmospheric Plating Bath

930‧‧‧Vacuum degassing tank

1001A / 1001B‧‧‧ device

1062A / 1062B‧‧‧ Wafer

1007A / 1007B‧‧‧Wafer Holder

1044‧‧‧Vacuum Atmospheric Interface

1200‧‧‧Electrodeposition equipment

1202/1204/1206/1212/1214 / 1216‧‧‧ Module

1222‧‧‧ Chemical dilution module

1224‧‧‧electrodeposition chamber

1226‧‧‧Dosing system

1228‧‧‧Pump unit

1230‧‧‧System Controller

1232‧‧‧Transportation Station

1242 / 1244‧‧‧ Cassette

1240 / 1246‧‧‧ Transfer Tool

1248‧‧‧ Aligner

1250‧‧‧Transfer Station

1300‧‧‧electrodeposition equipment

1302‧‧‧ Robot

1302a‧‧‧Robot track

1303‧‧‧ Spindle

1304 / 1308‧‧‧Accessible Station

1309‧‧‧Mounting bracket

1306‧‧‧ substrate

1307‧‧‧Plating Tank

1301‧‧‧FOUP

1 and 2 show views of a substrate when the substrate is immersed in an electrolyte in a plating bath during horizontal immersion (FIG. 1) and oblique immersion (FIG. 2).

Figure 3 shows electricity with a plating recirculation loop and a gas controlled recirculation loop. Plating system.

FIG. 4 illustrates a vacuum plating bath according to some embodiments.

FIG. 5 shows a cross-sectional view of a vacuum plating tank according to some embodiments.

FIG. 6 depicts a plating system according to various embodiments.

Figure 7 shows a plating system with a bypass duct.

FIG. 8 illustrates a plating system having two electrolyte storage tanks and two recycling circuits.

Figure 9 shows a plating system with three electrolyte storage tanks and three recirculation circuits.

Figure 10 shows a plating tank with a load lock chamber.

FIG. 11 is a graph showing the results of an electroplating process experiment performed at sub-atmospheric pressure and atmospheric pressure.

12 and 13 depict an alternative embodiment of a multi-tool plating apparatus according to some embodiments.

In this application, the terms "semiconductor wafer", "wafer", "substrate", "wafer substrate", and "partially fabricated integrated circuit" are used interchangeably. Those skilled in the art will understand that the term "partially manufactured integrated circuit" may represent a silicon wafer at any of the many stages of integrated circuit manufacturing. The wafer or substrate used in the semiconductor device industry generally has a diameter of 200 mm, or 300 mm, or 450 mm. In addition, the terms "electrolyte", "plating bath", "immersion bath", and "plating bath" are used interchangeably. The following detailed description assumes that the present invention is implemented on a wafer. However, the present invention is not limited to this. Work pieces can be of various shapes, sizes, and materials. In addition to semiconductor wafers, other work pieces that can utilize the present invention include various objects, such as printed circuit boards.

In the following description, numerous specific details are provided to provide a thorough understanding of embodiments of the invention. The disclosed embodiments may be practiced without some or all of these details. In other cases, well-known process operations are not described in detail so as not to unnecessarily obscure the disclosed embodiments. Although the disclosed embodiments are described in conjunction with specific embodiments, it should be understood that these specific embodiments do not limit the disclosed embodiments.

This disclosure is provided in the context of a method and apparatus for electroplating a substrate in a vacuum state. The vacuum-assisted method and related hardware disclosed herein allow rapid immersion into the substrate (eg, less than about 50 ms, less than 35 ms, about less than 20 ms, less than about 10 ms, or 5-15 ms) without forming harmful bubbles. In addition, some of the disclosed vacuum embodiments allow the substrate to be immersed during the immersion without applying an electrical bias to the substrate. In addition, some embodiments allow the substrate to be immersed in a slightly inclined or non-inclined manner so that all portions of the substrate are in contact with the plating solution substantially simultaneously. Many different embodiments may be useful in a variety of applications, including applications that include mosaic interconnects (examples of providing this functional tool are Sabre ^TM NExT ^TM , Sabre ^TM Extreme ^TM from Lam Research Corporation of Fremont, California, Sabre ^(TM) Excel ^(TM) , Sabre ^(TM) Max ^(TM ), etc.), wafer level package (WLP), through silicon via (TSV, examples of this functional tool are Sabre-3D ^(TM )), and electroless deposition (ELD).

Embodiments herein eliminate gas at the substrate / fluid interface before or during immersion, and by carefully controlling the entry profile of the wafer (e.g., vertical entry speed, tilt angle, and rotation speed) And greatly reduce the formation of bubbles. This allows the substrate to enter the plating solution faster, and thus achieves higher quality and more uniform plating / filling on the plating surface of the entire substrate. In addition, the removal of oxygen in the plating environment reduces the deleterious effects of metal erosion at the wafer surface.

As described above, bubble formation results in significant plating defects that include reduced plating or non-plating at the location where the bubbles occur. When the wafer is immersed in a horizontal or substantially horizontal orientation (parallel to a plane defined by the surface of the electrolyte) along a vertical immersion track, bubbles are likely to form. FIG. 1 shows a cross-sectional view of a typical bubble trapping scenario that occurs in a plating system 101. The horizontal wafer 103 held by the wafer holder 104 is lowered toward the electrolytic solution 107 in the liquid tank 105 along the vertical Z axis, and is finally immersed in the electrolytic solution 107. The vertical immersion of the wafer 103 in the horizontal direction generates bubbles 109 trapped on the bottom surface (plating layer) of the wafer 103. In an inverted (downward facing) configuration, buoyancy tends to pull the bubbles up to the active side of the wafer. Because the plating tank does not have an internal mechanism to drive bubbles around the wafer edge, and the only way around the wafer is to leave the wafer surface, it is quite difficult to remove these bubbles from the wafer surface. In addition, some embodiments use a clamping fixture (such as wafer holder 104 of FIG. 1) at the edge of the wafer, which supports the wafer during immersion. Bubble leaves wafer table The surface is perpendicular to the surface of the wafer surface, so the trapped state of the bubbles is worsened. Generally speaking, the wafer 103 rotates around an axis passing through its center and perpendicular to its plating layer. Such rotation causes the bubbles to leave through centrifugal force, but the attachment of many smaller bubbles to the wafer is quite tenacious and cannot be removed by rotation.

Angled immersion

One approach to addressing several of these issues is the use of angled wafer immersion. In this method, the wafer is tilted relative to a plane defined by the surface of the electrolyte, and at the same time the wafer is introduced into the electrolyte along a vertical path (along the Z axis). FIG. 2 depicts an immersion scenario 112 in which a wafer 103 is immersed into the electrolytic solution 107 along the Z axis, and at the same time, the wafer is also inclined with respect to the surface of the electrolytic solution 107 at an angle θ, for example. Due to the use of angled immersion, bubbles that might have been trapped on the surface of the wafer will be propelled by the help of buoyancy and the wave that advances from the front immersion edge toward the rear immersion edge, and therefore the bubbles will not It can be trapped again to escape from the atmosphere. In addition, a single wet front will also be established, so there will be no problem with collective wet fronts. In US Patent No. 6,551,487, and US Patent Application No. 13 / 460,423, filed on April 30, 2012, the patent name is "WETTING WAVE FRONT CONTROL FOR REDUCED AIR ENTRAPMENT DURING WAFER ENTRY INTO ELECTROPLATING BATH" , "Angle Wafer Immersion" is described in more detail, and its content is hereby incorporated by reference as part of the disclosure of this case. The rotation speed can be matched with the angled immersion to reduce the formation of air bubbles. As described above, the wafer holder can increase the trapping of bubbles.

Although angled immersion in a plating bath operating at atmospheric pressure significantly reduces bubble formation, it poses a problem. The plated surface of the substrate is in contact with the solution over a period of time, and several areas of the plated surface are in contact with the solution before other areas of the plated surface. As a result, some areas can establish fully developed concentrations and adsorption profiles of plating additives (accelerators, inhibitors, and / or homogenizers), while other areas have just come into contact with the additives. When electroplating begins, these areas with the fully developed additive distribution perform better than other areas without the fully developed additive distribution. In addition, when the substrate is electrically biased during entry, the area of the substrate that was initially in contact with the plating solution begins plating long before the area of the substrate that is later in contact with the plating solution is electroplated. Therefore, during the electroplating process, the leading edge portion of the substrate is electroplated to a greater extent than the trailing edge portion. In an atmospheric pressure electroplating bath, the amount of time required for angled immersion can be a fairly significant proportion of the total time required to fill the recessed features during electroplating, especially relatively small features. The resulting unevenness is undesirable.

In some embodiments of the vacuum chamber, the wafer angle during the immersion may be less than about 3 degrees from the horizontal plane. In some embodiments, the angle is less than about 2 degrees, and in some embodiments, the angle is less than about 1 degree.

In some embodiments, the angle at which the wafer is tilted changes during the immersion protocol. This can cause a reduction in bubble entrapment. In these embodiments, the "swing speed" may be controlled, that is, the speed at which the wafer is tilted from θ to horizontal (and vice versa) so as not to create turbulence and thus cause unwanted air entrapment. However, like many phenomena in a high-yield environment, there are trade-offs between efficiency and yield. In particular, if the swing speed is too slow, the yield will deteriorate, and if the swing speed is too fast, turbulence may be caused. In one embodiment, the wafer swing speed is between about 0.25-10 degrees per second. In another embodiment, the swing speed is between about 0.25-1.5 degrees per second. In another embodiment, the swing speed is between about 0.5-1 degrees per second. In another embodiment, the swing speed is about 1 degree or more per second. In order to reduce the entrapment of bubbles, the control of the effective tilt angle can be used independently or in combination with the Z-velocity change. In some embodiments, when the wafer is inclined to a horizontal plane at a first angle, the leading edge of the wafer contacts the plating solution; then the tilt angle of the wafer is increased to a second angle, and then lowered to, for example, 0 degrees. In other embodiments, when the wafer is tilted to the horizontal plane at a first angle, the leading edge of the wafer will contact the plating solution, and then the tilt angle is reduced to a smaller tilt angle before the tilt angle is finally reduced to 0 degrees. .

In some embodiments, the angle of inclination is established before immersion and remains unchanged during the immersion process.

The wafer can also be rotated during immersion. Like tilting, the wafer can be rotated at any time along the vertical track of the wafer to the electrolyte, as long as the wafer is rotated when entering the electrolyte. In an embodiment, for the step of immersing the wafer, the rotation speed of a 200mm diameter wafer is between about 10-180RPM, the rotation speed of a 300mm diameter wafer is between about 5-180RPM, and a 450mm diameter The rotation speed of the wafer is between about 5-150 RPM. Different rotation speeds can be used for the immersion step (first rotation speed) and the plating step (second rotation speed), and the post-plating step (additional plating speed). For example: wafers can rotate at special speeds, This allows the electrolyte to be recovered from the wafer after the wafer has been removed from the tank and, for example, when the electrolyte is cleaned from a plated wafer. The details of these rotations, as well as exemplary hardware for performing an angled immersion method, are described in more detail in U.S. Patent No. 6,551,487, and the contents of which are incorporated herein by reference.

During immersion, the vertical entry speed of the wafer may be constant or variable. The vertical speed can be changed to provide the best wet distribution of the wafer. For example, in some embodiments, during at least a part of the immersion process, the wafer is accelerated and / or decelerated to control the wet wave front of the electrolyte.

In some embodiments, two or three of the wafer's rotation, vertical movement, and tilt can be adjusted simultaneously using a suitable mechanical control system. The adjustment mechanism can operate on a portion of the wafer holder located outside the vacuum element of the plating bath. When the wafer is moved, tilted, and / or rotated, the wafer holder spindle or other rotating / tilting / moving components can be connected to the plating tank via a bellows, vacuum bearing, and / or other suitable interface to maintain vacuum. The vacuum seal wall or cover engages.

Immersion under vacuum

In different embodiments disclosed herein, the wafer is immersed under vacuum. Under the conventional electroplating technology, there are (1) rapid immersion into the wafer; and (2) reduced air trapping; a trade-off between the two. However, the use of a vacuum plating bath allows rapid immersion without the formation of air bubbles, because virtually no air is trapped under the wafer during wafer immersion. Because bubbles are significantly less likely to form on the substrate surface under vacuum, the examples herein allow for a faster immersion time, which is approximately used for additive adsorption (about 100 ms) and nucleation (about 50 ms) Is in the order of magnitude, and in many instances is faster than that time range. The total immersion time can be quite important. For example, this is because during the immersion, part of the wafer will come into contact with the electrolyte, while the other part will not. Depending on the plating conditions and the thickness of the seed layer, it is often important to immerse the wafer as quickly as possible. The fast immersion time will result in a more uniform plating layer and a more uniform filling of features on the entire substrate.

When using an atmospheric pressure plating bath and angled entry, the immersion time of a 300mm wafer can be less than about 150ms. The 450mm wafer immersion time can be less than about 225ms. When the immersion step is performed in a tank in which the pore space above the electrolyte has a low pressure (e.g., a pressure below atmospheric pressure), the risk of bubble formation is greatly reduced, especially at high entry speeds. In some cases, when sub-atmospheric plating baths are used, the immersion time does not exceed filling About 10% of the total time of the smallest feature on the plated substrate (or no more than about 10% of the total time of filling the size feature on the plated substrate). As mentioned above, in some embodiments, the immersion time may be less than about 50 ms, less than about 35 ms, less than about 20 ms, less than about 10 ms, or about 5-15 ms. These speeds may be suitable for wafers with a diameter of 300 mm and / or wafers with a diameter of 450 mm. In some cases, the vertical entry speed of the substrate is between 200-400mm / s. The principles described herein allow faster vertical entry speeds than typical entry speeds used in conventional methods.

In different embodiments, the plating bath with the plating solution and the wafer (or other substrate) is under vacuum (for example, about 100 Torr or less, about 30-100 Torr, or about 40-80 Torr) (Or sub-atmospheric pressure between 30-50 Torr). The pressure should be maintained at a sub-atmospheric level at least during wafer immersion. In some embodiments, during the beginning of the plating process (eg, during about 0.5% or 1% of the beginning of the plating time, during a period of about 10ms or 20ms at the beginning of the plating, or when the plating is initially about 0.5% Å or 1Å metal), the pressure is also maintained at the sub-atmospheric level. In some embodiments, the pressure is maintained at a sub-atmospheric level until the plating stops.

In order to replace the wafer, refresh the plating solution, etc., it may be necessary to periodically expose the plating bath to a higher pressure (such as environmental pressure). In some embodiments, the entire plating process is performed at sub-atmospheric pressure, and the plating bath is exposed to ambient pressure only when no wafers are being plated. If a load lock chamber is used (to be discussed in more detail below with reference to FIG. 10), when replacing a plated wafer with an unplated wafer, it may be possible to operate the plating bath without breaking the vacuum.

Generally, the plating bath is in fluidic communication with other components of the plating system. These other components include: a storage tank for the plating solution, a source of the solution that makes up the plating solution, different sensors, filters, and in some embodiments for removing the dissolution from the plating solution and / or the pre-wet solution Degasser for gas. When the plating tank is operated at sub-atmospheric pressure, other system components in direct fluid contact with the plating tank should also be operated at sub-atmospheric pressure. The different embodiments shown in the figures provide mechanisms for maintaining a vacuum during electroplating of all components in fluid communication with the plating bath. Other components may still be exposed to atmospheric pressure during plating. These non-vacuum components will only interface with vacuum components during certain periods, especially when the plating bath itself is not exposed to vacuum.

Control of dissolved gas

In various embodiments, the concentration of one or more gases in the electrolyte is controlled by using a degasser operating under vacuum to substantially remove all of the dissolved gas in the electrolyte. If the plating solution is not degassed before entering the vacuum plating environment, the solution will easily bubbling, and bubbling is a state that is not beneficial to the production of high-quality plating. In some embodiments, the concentration of the dissolved gas in the plating solution is further controlled by selectively injecting the gas back into the degassed electrolyte at a predetermined concentration for a particular application. More than one of these gases should be added at a relatively low concentration to avoid bubbling of the plating solution under vacuum. In some embodiments, oxygen is added at a concentration of single digits per billion or parts per billion (eg, below about 10 ppm, or below about 1 ppm). Molecular oxygen is thought to play a role in the activity of organic plating additives (called promoters). In some embodiments, the concentration of all or part of the gas in the electrolyte is reduced to a range of low ppb or lower (eg, exceeding the size detected using current tools). This can be done by passing the electrolyte through a degasser operated under vacuum. Degasser and vacuum technology are described in US Patent Application Nos. 12 / 684,787 and 12 / 684,792, filed on January 8, 2010, and the contents of which were previously incorporated by reference into the disclosure of this case by reference.

In some embodiments, we would like to have different plating solutions in contact with the anode (anolyte) and the cathode (calyte). The anolyte and catholyte may have the same species at different concentrations (eg, copper ions of different concentrations), and / or the catholyte and anolyte may have different species in the solution (eg, catholyte may be present) And there are no organic plating additives in the anolyte, such as accelerators). Therefore, some embodiments utilize a partially or completely separated fluid circuit between the catholyte and the anolyte. Catholyte and anolyte can be independently optimized in this way.

One advantage of the at least partially separated fluid circuit is that the oxygen concentration can be maintained at different levels in the catholyte and anolyte when the oxygen is delivered to the plating bath. In some embodiments, we expect the oxygen concentration in the catholyte to be 0 ppm, or as close to 0 ppm (or 0 ppb) as possible, and at the same time to maintain the oxygen concentration in the anolyte at a low, non-zero (eg, 0.2-2 ppm) ). Because the presence of oxygen increases the degree and possibility of dissolution / oxidation of the seed layer during immersion, it is better to have zero oxygen in the catholyte in some cases. It may be desirable to have a small amount of oxygen in the anolyte.

A related advantage with having at least partially separated fluid circuits is to eliminate the need for an oxygen servo connected to the catholyte. In conventional electroplating, two oxygen servo devices can be used: one is a servo device that controls the amount of oxygen in the catholyte, and one is a servo device that controls the amount of oxygen in the anolyte. In the embodiment herein, because the deaerator / vacuum tank can reduce the oxygen level in the catholyte to about zero ppm, there is no need for a servo device that controls the amount of oxygen in the catholyte.

In some embodiments, we would like to have a small, carefully controlled amount of oxygen in the catholyte. This can be achieved, for example, by the selective injection of oxygen back into the degassed catholyte at a predetermined concentration. Such a situation can be achieved by placing an oxygen injector downstream of the degasser in a fluid circuit including a primary atmospheric plating tank. Not limited to any particular theory or action mechanism, I believe that a small amount of oxygen can promote the conversion of certain additives into their useful forms (such as: mercaptopropane sulfonic acid (MPS) into dimercaptopropane sulfonic acid (SPS)). US Patent Application No. 13 / 229,615 filed on September 9, 2011, with the patent name "By-Product Mitigation in Through-Silicon-Via Plating", and in 2011 U.S. Patent Application No. 13 / 324,890, filed on December 13, entitled "Configuration and Method of Operation of an Electrodeposition System for Improved Process Stability and Performance", further discusses the relationship between the control of dissolved oxygen and its effectiveness on additives The above documents are incorporated into the disclosure of this case by reference to the entirety.

The embodiments herein also allow different dissolved gas (eg, oxygen) concentrations at different locations in the fluid circuit. The oxygen concentration in the electrolytic solution can be changed between, for example, a plating solution storage tank and a plating tank. The degasser, vacuum plating tank, electrolyte storage tank, and other components (valves, vacuum pumps, etc.) operate in a combined manner to provide the desired gas content in different parts of the device. For example: Figure 3 will depict a device that allows such control.

Figure 3 shows the implementation of a vacuum plating tank equipment capable of controlling the dissolved gas content of the plating solution. In this embodiment, the vacuum plating tank 301 includes a pressure sensor 318, and in the recirculation circuit 302, the vacuum plating tank 301 is in continuous fluid communication with the vacuum plating solution storage tank 304, the pump 306, and the deaerator 308. This degasser may be connected to the vacuum pump 310. The vacuum plating solution storage tank 304 is maintained under vacuum, and is further connected to the gas control circuit 312. The gas control circuit 312 may include a dissolved gas sensor 314, a controller 350, and a gas injection unit 355. For example In other words, the controller 350 may be a servo device controller. As mentioned above, in some embodiments, we expect a specific level of more than one gas in the plating solution. The gas control circuit 312 allows the amount and kind of dissolved gas to be manipulated as desired. First, the dissolved gas sensor 314 senses the amount of dissolved gas present in the plating solution. Next, the controller 350 uses the measurement results of the dissolved gas to determine whether more gas should be injected into the plating solution. If the level of more than one dissolved gas is too low, the controller 350 will instruct the gas injection unit 355 to inject the desired gas into the plating solution. The control circuit 312 enables the amount of dissolved gas in the plating solution to be closely monitored and controlled over time. Because once or all of the dissolved gas is removed, it is relatively easy to achieve the desired gas content, the gas control loop 312 is particularly advantageous in these embodiments. The degassing plating solution provides a "blank slate", which is easily customized by injecting it into a desired gas at a desired gas concentration.

The vacuum plating tank 301 in FIG. 3 shows that there is no partition structure between the cathode / wafer 322 and the anode 323. When an undivided structure is used, the fluid channels shown correspond to the fluid channels of the electrolyte. Because the two flow systems are the same and a non-separated structure is used therein, there are no separate channels for the cathode and anode. However, when a membrane or other separation structure is disposed between the wafer 322 and the anode 323, the separated fluid circuit can be used for catholyte and anolyte. Unless otherwise stated, the fluid circuits disclosed herein may relate to an integral electrolyte fluid circuit, a catholyte fluid circuit, or an anolyte fluid circuit. For example, if the plating tank 301 in FIG. 3 includes a separation film between the wafer 322 and the anode 323, the fluid channel shown may correspond to the catholyte fluid channel. Although the fluid channel of the anolyte may be relatively simple in some embodiments, similar or identical fluid channels may be provided for the anolyte.

In one embodiment, oxygen is supplied to the subatmospheric plating tank at a relatively low level and oxygen is provided to the rest of the system outside the storage tank or subatmospheric plating tank at a slightly higher concentration. In this case, the plating additive can be "reconditioned" in the storage tank. Tank-based reforming allows the plating tank to operate at an oxygen concentration level where such recovery is unlikely to occur, thereby minimizing dissolution of the seed layer.

Power to the substrate during entry

Because wafers enter the electrolyte fairly quickly, the need for potentiostatic wafer entry can be significantly reduced or eliminated. Among many known electroplating technologies, the controller Or other power supplies provide power to the wafer during immersion to help achieve a uniform coating. For example, before and during the immersion, the controller can apply a constant cathode potential or current to the wafer to protect the seed layer from dissolution. This technology is referred to as a potentiostatic wafer entry, and is discussed further in US Patent No. 6,946,065, filed on November 16, 2000, and its contents are incorporated herein by reference for disclosure. The method of constant potential entry requires careful control of the current density applied to the wafer to achieve a uniform coating. In the conventional constant potential entry example, the current density control system is particularly difficult because the wetted wafer area changes as the substrate is gradually immersed. However, because the immersion occurs quite quickly so that the seed layer does not dissolve during immersion, the embodiments disclosed in this case significantly reduce or eliminate the need for constant potential entry. Therefore, in some embodiments, no cathode or anode bias is applied to the wafer during immersion. These embodiments are advantageous because electroplating does not occur during immersion. Therefore, the distribution of the organic plating additive can be completely established in the entire area of the substrate surface before the start of plating. Because one area of the substrate surface does not begin plating before any other area of the substrate is plated, fast entry is also advantageous. In addition, the plating control system is less sensitive, which means that the plating system does not need to be so careful to control the current density, and other key factors when entering using a potentiostatic wafer. Moreover, these embodiments may use less complex and less expensive controllers.

System controller

In some embodiments, a system controller (which may include more than one physical or logical controller) controls some or all operations of the process tool. The controller typically includes more than one memory device, and more than one processor. The processor may include a central processing unit (CPU) or computer, analog and / or digital input / output connections, a stepper motor control board, and other similar components. Instructions for implementing appropriate control operations are executed on the processor. Such instructions may be stored in a memory device associated with the controller, or such instructions may be provided via a network. In some embodiments, the system controller executes system control software.

The system control software can include control timing, mixture of electrolyte components, inlet pressure, plating tank pressure, plating tank temperature, wafer temperature, current and voltage applied to the wafer and any other electrodes, wafer position, wafer rotation, Wafer immersion speed and other parameters for a particular process performed by the process tool. The system control software can be set in any suitable way. For example, different process tool component subroutines or control objects can be written to control the execution of different process tool systems. The operation of process tool components necessary for the process. The system control software can be encoded in any suitable computer-readable programming language.

In some embodiments, the system control software includes input / output control (IOC) sequence instructions for controlling the different parameters described above. For example, each phase of the plating process may include more than one instruction for execution by the system controller. Instructions for setting process conditions for the immersion process stage may be included in the corresponding immersion recipe stage. In some embodiments, the plating formulation stages may be arranged sequentially, so that all instructions for the plating process stage are executed simultaneously with the process stage.

Other computer software and / or programs can be used in some embodiments. Examples of program sections or programs used for this purpose include: substrate positioning program, electrolyte composition control program, pressure control program, heater control program, and potential / current power supply control program.

In some examples, the controller controls more than one of the following functions: gas concentration in the electrolyte, wafer immersion (movement, tilt, rotation), fluid transfer between multiple tanks, and tanks and related components in the fluid circuit Vacuum control. The controller can control the gas concentration by, for example, using a gas concentration measured by a dissolved gas sensor, and instructing the gas injection unit to introduce the gas as desired. The wafer immersion can be controlled by, for example, instructing the wafer lifting assembly, the wafer tilting assembly, and the wafer rotating assembly to move as desired. The controller may control fluid transfer between the plurality of tanks by, for example, indicating that a part of the valve is opened or closed and a part of the pump is opened or closed. The controller can be based on the sensor output (such as when the current, current density, potential, pressure, etc. reach a certain threshold), the operating sequence (such as: opening the valve at certain points in the process), or according to the received from the use Instructions to control these implementations.

application

The embodiments disclosed herein may provide more than one advantage over conventional electroplating techniques. First, the vacuum plating bath allows the substrate to be dipped into the electrolyte fairly quickly. High-speed immersion can cause significantly lower dissolution of the seed layer and significantly fewer changes / defects in the resulting feature fill. High-speed immersion can also reduce the transient period of entry, making it equivalent to (and less than in some instances) a transient period of adsorption and nucleation. In addition, in some embodiments, immersion is performed without applying an electrical bias to the substrate, thereby avoiding plating during the immersion process. Second, the vacuum plating bath reduces the number of defects caused by bubble formation by substantially reducing (and eliminating in some instances) the gas close to the wafer surface during entry. In addition, by reducing or removing O ₂ near the wafer surface during entry, the erosion-type defects caused by O ₂ may be reduced. Similarly, the step of performing a pre-wetting operation under vacuum using a de-aerated pre-wetting fluid can also help reduce the erosion of the seed layer. The embodiments herein are also provided to reduce or eliminate dissolved gas from the plating solution. One of the benefits is to further reduce erosion-related defects caused by O ₂ .

The step of removing the dissolved gas from the plating solution provides a convenient way to control the precise amount / composition of the dissolved gas in the solution. After the dissolved gas is removed to a negligible concentration point, a desired amount of gas can be injected into the solution in order to achieve a gas concentration with a better electrolyte composition. The dissolved gas sensor and servo device can be used to strengthen the control of dissolved gas to maintain the gas concentration within a specific range.

Some embodiments herein allow electroplating to occur at lower temperature states than those typically used in conventional electroplating. For example, some embodiments allow electroplating to occur below the typical freezing temperature of the plating solution at atmospheric pressure. In addition, embodiments herein allow electroplating to occur at reduced pressure, and in some instances, the pressure may drop to the boiling point of the plating solution. In some embodiments, the low-pressure conditions in the plating chamber are continuously maintained, such as when using a load lock chamber design. In other embodiments, the pressure is cycled between atmospheric and sub-atmospheric states.

The vacuum plating tank can be used in combination with different wafer entry control equipment, such as: wafer lifting mechanism, wafer tilting mechanism, wafer rotation mechanism, and various wafer disturbance mechanisms, including (but not limited to): The sonic fluid disturbance and the periodic direction of the rotation axis change. Each of these elements can contribute to a reduction in bubble formation, and they can be optimized simultaneously to produce the fewest bubbles possible.

An additional advantage is that when the wafer is placed over a plating bath waiting to be immersed in the plating solution, the wafer is simultaneously in a vacuum state and thus does not come into contact with harmful gases such as oxygen. Such a situation eliminates any copper oxidation reactions that may occur at this stage in the atmospheric plating bath.

In an embodiment herein, the apparatus for electroplating includes an electrochemical cell capable of operating in a vacuum state (ie, less than atmospheric pressure). In many cases, the device includes a degasser capable of substantially degassing the electrolyte and / or the pre-wet solution before contacting the substrate. If the electrolyte / pre-wet fluid is not degassed before entering the vacuum chamber and contacting the substrate under vacuum, the dissolved gas may be released from the fluid when it enters the chamber. The release of dissolved gas can lead to the formation of air bubbles within the perforations and / or on the wafer surface. Although not limited to any particular theory or model, perforation The bottom has a negative curvature, and I believe that this location is particularly prone to bubble formation and gas release from the electrolyte / pre-wet fluid. If this release occurs, because the fluid is supersaturated in a vacuum, bubbles will be formed from the fluid. After the pre-wetting process and during the electroplating, the bubbles thus formed can stay there, thus suppressing electroplating and causing related defects at this location.

The equipment can include more than one electroplating fluid circuit, which can combine the electrochemical tank with more than one electrolyte storage tank, pump, deaerator, dissolved gas sensor, servo device controller or other controller, gas The injection unit and the valve are connected. Some or all of the aforementioned features may appear in some embodiments.

FIG. 4 shows an exemplary vacuum plating bath. The equipment includes: a wafer lifting assembly 402 for moving the substrate in the z direction (up and down); a wafer tilting assembly 404 for tilting the wafer relative to the horizontal plane; and a wafer rotating assembly 406 for plating During the wafer rotation. These components work together to control the vertical speed, angle, and rotation rate of the wafer during plating, and they are particularly important for controlling the plating system at the beginning of the plating process. Second, the apparatus according to the embodiment in FIG. 4 includes a vacuum-compatible plating tank 410 with a corresponding vacuum top plate 408. These elements 410 and 408 provide a vacuum environment where electroplating can occur. The electrochemical cell 410 also includes a wafer holder 424 and a cone 422. When the wafer is supported in the substrate holder 424, the cone 422 presses down the back of the wafer. FIG. 5 provides components of an additional plating bath 410.

FIG. 5 shows a plating apparatus 500 according to one embodiment. First, the plating equipment 500 has: a wafer holder; a plating tank 530 having a volume for containing a plating bath fluid 534; an anode; and a tophat 533, which can surround the upper part of the plating equipment ( For example: substrate holder when substrate is loaded). The top cap 533 can maintain a vacuum state on the plating tank, and the top cap 533 corresponds to the vacuum top plate 408 of FIG. 4. The substrate holder substantially includes: a lip seal 522 installed in the cup 524 having a cup bottom 525; and a cone 526 that is movable relative to the cup 524 and the lip seal 522. The substrate holder is used to fix the substrate by pressing the substrate (not shown) into the lip seal 522.

In some embodiments, as shown in FIG. 5, the cup body 524 is supported by the cup post 528 and is connected to the cup portion and the lifting portion of the cone (not shown, but located above the cone 526). The cup post 528 passes through a portion of the cone 526 to allow the cone to move up and down relative to the cup 524 by a pneumatic mechanism (not shown). Therefore, the clamshell assembly (or substrate holder) can be closed to close the substrate (not shown) on the periphery of the substrate against the lip seal 522. seal. When the cone 526 is in the retracted / up position and therefore the grab assembly (or substrate holder) is an open configuration as shown in FIG. 5, a substrate can be loaded into the grab assembly and placed side by side. On the lip seal 522. Once the substrate is placed on the lip seal 522, the cup post 528 can be compressed (ie, moved through the cone 526), so that the cup 524 and the cone 526 move toward each other to squeeze the bottom surface of the cone 526 against the post The back surface of the substrate causes the outer periphery of the other side of the substrate (ie, the side to be plated) to be pressed against the lip seal 522 to form a fluid seal.

The substrate holder also typically includes a plurality of electrical contacts (not shown in FIG. 5). During the plating operation, the electrical connectors are powered by the power supply (not shown) of the plating equipment to the substrate. In some embodiments, the electrical contacts are formed as electrical contact fingers, but other shapes / types of electrical leads can also be used to supply current to the substrate. As described above, during the electroplating, the electrical connector is substantially protected by a fluid seal formed between the substrate and the lip seal 522, which isolates the plating solution from the backside of the substrate and away from the electrical contacts during the electroplating. In some embodiments, the nozzle 514 is used to perform cleaning of the electrical contact. For example, it is to change the height of the nozzle relative to the electrical contact, and adjust the flow rate of the cleaning fluid and the rotation of the substrate holder. Rate, chemistry of the cleaning solution, and other suitable parameters to perform cleaning of the electrical contacts.

Once the substrate is loaded and sealed in the substrate holder (that is, sealed by the cup 524 and the cone 526 and sealed against the lip seal 522), the substrate holder (or grab assembly) The proximal end is ready to descend into the plating bath (assuming an angled immersion is used). The plating bath contains an electrolytic solution contained in a plating tank 530 of the plating equipment 500, and the plating tank 530 contains (or has a containing volume) a plating bath fluid 534. In some embodiments, the plating tank 530 may include an anode chamber and a cathode chamber separated by a membrane portion or other separation structure. In addition, the slot 530 may include a channeled ionically resistive plate, sometimes referred to as a high resistance virtual anode (HRVA), which serves as a current distribution controller and flow diffuser 538, such as the United States Patent cases Nos. 7,967,969, 7,622,024, and 8,308,931 are described, the contents of which are hereby incorporated by reference as a part of the disclosure of this case.

During the plating operation, the substrate holder is lowered into the plating tank volume 532 for containing the plating bath fluid 534, thereby lowering the working surface (downward surface) of the substrate to the fluid level 535 of the plating bath fluid / solution 534 Hereinafter, the working surface of the wafer is immersed in the plating solution.

The plating apparatus 500 may optionally include a cleaning device 510, which may It includes a nozzle 514, a cleaning fluid supply conduit fluidly connected to the nozzle 514, and a nozzle arm 513 to which the nozzle 514 is fixed. In some embodiments, the cleaning device 510 includes a nozzle arm actuator 512 mechanically connected to the nozzle arm 513 and configured to move the first nozzle 514 and the nozzle between the retracted position and the cleaning position. Arm 513. The rinse mask 570 may be used to protect the components of the device from the spray of the cleaning liquid. The recovery mask 560 may be used to help recover the used cleaning fluid. In some embodiments, a pre-wetting mechanism (not shown) can be used to pre-wet the plating surface of the substrate. Although the pre-wetting mechanism is provided so that the pre-wetting fluid will contact the plating surface of the substrate, the pre-wetting mechanism and the cleaning device 510 may be mechanically similar. In some cases, pre-wetting may occur outside the plating tank 530.

FIG. 6 shows an additional example of a vacuum plating tank 601 in fluid communication with a plating fluid storage tank 604. This embodiment is similar to the embodiment in FIG. 3, but is a bit simple. The area in the vacuum plating tank 601 is maintained in a vacuum state. The apparatus includes: a degasser 608 for removing dissolved gas from the plating solution; and a pump 606 for moving the plating fluid through the plating fluid circuit 602. Degasser and its use are described in US Patent Application Nos. 12 / 684,787 and 12 / 684,792, which were previously incorporated by reference into the disclosure of this case. The plating fluid circuit 602 connects the vacuum plating tank 601 with the plating fluid storage tank 604, the pump 606, and the deaerator 608. The vacuum pump 610 may be connected to the deaerator. In the embodiment of FIG. 6, the complete plating fluid circuit (including: the plating fluid storage tank 604) is maintained in a vacuum state.

In the embodiments herein, any one that is in open fluid communication with the vacuum plating tank during plating should be maintained in a vacuum state during plating to ensure that the pressure in the vacuum plating tank is properly controlled. The fluid sensing circuit 612 connects the plating fluid storage tank 604 with the dissolved gas sensor 614. The dissolved gas sensor ensures that the dissolved gas is at an acceptable level for electroplating. If the level of the dissolved gas is too high, it may lead to the formation of air bubbles in the plating solution, resulting in uneven plating. In addition, since oxygen oxidizes the copper seed layer, the presence of dissolved oxygen can be detrimental to the plating process. Therefore, in some embodiments, the dissolved gas sensor 614 is an oxygen sensor. The vacuum plating tank 601 may also include a pressure sensor 618. Although those skilled in the art will understand that many types of pressure sensors can be used, one possible type of pressure sensor that may be used is a Baratron pressure converter. The device optionally includes a pre-humidifier 616, which is used to provide degassed deionized water or other pre-humidifying solution to the surface of the substrate under vacuum before immersion in the plating fluid. Pre-humidifier can further reduce the need to completely remove the substrate without the formation of air bubbles Immersion time required for immersion in the plating fluid. Because the substrate system is shown in the plating position (ie, the lowered position, dropped into the electrolyte), the pre-humidifier system is located above the plane of the wafer. However, I understand that the pre-humidifier should be configured so that the pre-humidifier can apply a pre-humidifying solution to the plated surface of the substrate when the substrate is in its non-plated position.

FIG. 7 shows an additional embodiment of a vacuum plating tank 701 in fluid communication with the plating solution storage tank 704. In this embodiment, the plating circuit 702 is opened during plating, and the vacuum plating tank 701 is connected to the pump 706 and the deaerator 708. The electrolyte bypasses the electrolyte storage tank during electroplating and instead flows through a conduit connected to a plurality of valves 722. Each of these elements is maintained in a vacuum state. When electroplating does not occur, the valve 722 can be opened, thereby opening the non-plating fluid circuit 720. The non-plating fluid circuit 720 connects the vacuum plating tank 701 with the plating solution storage tank 704, the pump 706, and the deaerator 708. In this embodiment, the plating solution storage tank 704 is maintained at the atmospheric pressure. Therefore, the plating solution storage tank 704 must be fluidly separated from the vacuum plating tank during plating. To maintain a sufficient level of additives in the plating solution, the plating solution in the plating solution storage tank 704 should be periodically replaced or replenished. The level of the dissolved gas in the plating solution in the embodiment of FIG. 7 is about 2 ppm, which corresponds to the level of the dissolved gas that can be achieved after a single pass through a currently available degasser.

FIG. 8 shows an embodiment of a vacuum plating tank 801 with a dual tank system. In this embodiment, the vacuum plating tank 801 is in continuous fluid communication with the vacuum plating solution storage tank 804, the pump 806, and the deaerator 808. The vacuum plating solution storage tank 804 is maintained in a vacuum state, and is in fluid communication with the atmospheric pressure plating solution storage tank 825, the valve 822, and the pump 824. When electroplating does not occur, the fluid circuit connected to the atmospheric pressure plating bath 825 may be opened, but when electroplating occurs, the circuit should be closed. The atmospheric plating bath 825 can be used to provide a new plating fluid to the vacuum plating bath 804 between multiple plating operations. The level of dissolved gas in the plating solution in the plating tank 801 may be less than about 1 ppm. Having a dual storage tank and one of the tanks in a vacuum state substantially reduces the amount of dissolved gas in the plating fluid and provides additional control of the composition of the plating fluid.

FIG. 9 shows an embodiment of a vacuum plating tank 901 with a triple storage tank system. In this embodiment, the vacuum plating tank 901 is in continuous fluid communication with the vacuum plating solution storage tank 904, the pump 906, and the deaerator 908. The vacuum plating solution storage tank 904 is maintained in a vacuum state, and is further connected to the vacuum degassing tank 930, the pump 926, and the valve 922. The valve 922 is closed during the plating, so that the vacuum plating solution storage tank 904 and the vacuum degassing tank 930 are made when the plating occurs No fluid communication. However, when electroplating does not occur, the valve 922 may be opened, and the plating solution may flow between the vacuum plating solution storage tank 904 and the vacuum degassing tank 930. The atmospheric pressure plating solution storage tank 940 may be in fluid communication with the vacuum degassing tank 930 periodically. A pump 916 may be provided so that the plating solution flows between the vacuum degassing tank 930 and the atmospheric pressure plating solution storage tank 940 when the valve 923 is opened. The valve 923 should be opened periodically to replenish or exchange the plating solution, and to ensure that the concentration of additives or other plating solution components is maintained in their desired range. The set of valves 922 between the vacuum plating solution storage tank 904 and the vacuum degassing tank 930 should not be opened at the same time as the set of valves 923 between the vacuum degassing tank 930 and the atmospheric pressure plating solution storage tank 940. Such a situation would allow the vacuum plating tank 901 to be maintained in a vacuum state at all times. For example, the dissolved gas in the plating solution in this embodiment can be controlled to a level significantly less than 1 ppm.

Fig. 10 shows an embodiment of a vacuum plating tank equipped with a load lock chamber device. When replacing plated wafers with unplated wafers, the load lock chamber device allows the plating bath to operate without breaking the vacuum. Figure 10 shows the vacuum plating baths located in two different locations (ie, although this figure shows two wafers 1062A and 1062B and the related wafer holders 1007A and 1007B, the two wafers are intended to be presented in (A single wafer 1062 and a holder 1007) in different positions A and B). When the wafer is in the vacuum load lock chamber position in the non-vacuum part of the device 1001A, the plating bath is sealed in a vacuum state, and the wafer 1062 can be loaded. Next, the vacuum load lock chamber is evacuated to a vacuum state, and a slit valve (not shown in the figure) or other appropriate valve in the vacuum atmosphere interface 1044 is opened. The wafer 1062 then passes through the position of the vacuum plating bath in the vacuum portion of the device 1001B under vacuum, and then plating can occur.

Figure 11 shows the results of studies conducted to ensure that low-voltage plating can be successful. The two questions explored in the study were (1) whether the water-insoluble components of the plating fluid would evaporate in large quantities at low pressures, and (2) whether the plating fluid would boil at pressures significantly above the expected boiling point of water. These issues are important because electroplating may fail if the water-insoluble components evaporate under vacuum pressure, or if the plating solution begins to boil during electroplating. In order to explore these problems, a plating solution or a deionized aqueous solution is exposed to a pressure range between atmospheric pressure and a vacuum state (particularly 10, 20, 40, and 760 Torr). At each pressure, observe the samples for signs of boiling, and take a gas sample from the above plating solution and analyze it with a residual gas analyzer. For water and plating solutions, a boiling state was observed at 10 Torr, and the two solutions intermittently boiled at 20 Torr. No boiling was observed for the two solutions at 40 or 760 Torr. This situation indicates Electroplating should occur at least above 20 Torr. There was no significant difference between the RGA analysis of deionized water and the RGA analysis of the plating solution at any of the tested pressures. This means that the water-insoluble components of the plating fluid do not evaporate in large quantities, making low pressure plating a viable option.

One aspect of the disclosure involves an electroplating apparatus. The plating equipment includes a plating tank connected to a mechanism for reducing the pressure in the plating tank to a sub-atmospheric pressure level. The apparatus also includes a controller for making the pressure in the plating tank to a sub-atmospheric pressure while the plating substrate is immersed in the plating solution. The device can also include a variety of other features, such as a recirculation circuit with a storage tank, deaerator, pump, etc. as described in the figure. These circuits can be selectively separated or incorporated into the electroplating tank at atmospheric pressure as required. In some cases, the apparatus is used for immersion of a substrate at a pressure below about 100 Torr. In some cases, the device is used for substrate immersion for a duration of about 50 ms or less, or about 35 ms or less, or about 25 ms or less, or about 15 ms or less. In some cases, the device is used for substrate immersion for a duration that refers to no more than about 10 times the total time required to completely electrically fill the average or medium-sized features on the plated surface of the substrate. %.

Vacuum plating baths can be integrated into multi-tool semiconductor processing equipment. The multi-tool equipment may have more than one vacuum plating tank, more than one atmospheric pressure plating tank, and various other components. FIG. 12 shows an exemplary multi-tool device that can be used to implement the embodiments herein. The electrodeposition apparatus 1200 may include three separated plating modules 1202, 1204, and 1206. In addition, three separated modules 1212, 1214, and 1216 can be used for different process operations. For example, in some embodiments, one or more of the modules 1212, 1214, and 1216 may be a spin cleaning rinsing (SRD) module. In other embodiments, one or more of the modules 1212, 1214, and 1216 may be post-electrofill modules (PEMs), each of which is used to perform a function, such as: Edge bevel removal, backside etching, and acid cleaning of the substrate after the substrate is processed by one of the plating modules 1202, 1204, and 1206.

The electrodeposition apparatus 1200 includes a central electrodeposition chamber 1224. The central electrodeposition chamber 1224 is a chamber containing a chemical solution used as a plating solution in the plating modules 1202, 1204, and 1206. The electrodeposition apparatus 1200 also includes a dosing system 1226 that can store and transport additives for plating solutions. The chemical dilution module 1222 can store and mix chemicals used as an etchant. Filter and pump unit 1228 can filter plating for central electrodeposition chamber 1224 And can transfer the plating solution to the plating module.

The system controller 1230 provides the electrical and interface controls needed to operate the electrodeposition equipment 1200. The system controller 1230 has been introduced in the above-mentioned system controller unit and is further described herein. A system controller 1230 (which may include more than one physical or logical controller) controls some or all of the characteristics of the plating equipment 1200. The system controller 1230 typically includes more than one memory device and more than one processor. The processor may include a central processing unit (CPU) or computer, analog and / or digital output / input connections, a stepper motor control board, and other similar components. Instructions for implementing suitable control operations as described herein may be executed on a processor. Such instructions may be stored in a memory device associated with the system controller 1230, or they may be provided via a network. In some embodiments, the system controller 1230 executes system control software.

The system control software in the electrodeposition equipment 1200 may contain a number of instructions. These instructions are used to control timing, electrolyte composition mixing (including: concentration of more than one electrolyte component), electrolyte gas concentration, inlet pressure, plating tank pressure, plating tank temperature, substrate temperature, applied to the substrate and any other electrodes Current and potential, substrate position, substrate rotation, and other parameters of a particular process performed by the electrodeposition equipment 1200.

The system control logic can be configured in any suitable way. For example, various process tool component subprograms or control objects can be written to control the operations of the process tool components required to perform various process tool processing. The system control software can be encoded in any suitable computer-readable programming language. This logic can also be implemented as hardware in a programmable logic device (such as an FPGA), an ASIC, or other suitable carrier.

In some embodiments, the system control logic includes input / output control (IOC) sequence instructions for controlling various parameters described above. For example, each stage of the plating process may include more than one instruction executed by the system controller 1230. The instructions for setting the process conditions of the immersion process stage may be included in the corresponding immersion recipe stage. In some embodiments, the electroplating recipe phases can be sequentially arranged so that all instructions for the electroplating process phase are executed simultaneously with the process phase.

In some embodiments, the control logic can be divided into different parts, such as programs or program segments. Examples of logic sections used for this purpose include: substrate positioning section, electrolyte composition control section, stripping solution composition control section, solution flow control section, pressure control section, heater control section, and potential / Current power supply control section. The controller can use examples If instructed, the substrate holder is moved (rotated, raised, tilted) as desired to execute the substrate positioning portion. The controller can control the composition and flow of different fluids (including but not limited to electrolytes and stripping fluids) by instructing some valves to open or close at different points in the process. The controller can execute a pressure control program by instructing some valves, pumps, and / or sealing elements to open or close. Likewise, the controller may execute a temperature control program by, for example, instructing more than one heating and / or cooling element to be turned on or off. The controller can control the power supply by instructing the power supply to provide a desired current / potential level throughout the process.

In some embodiments, there may be a user interface associated with the system controller 1230. This user interface may include a graphical software display that displays the screen, equipment and / or process conditions, and user input devices, such as: pointing devices, keyboards, touch screens, microphones, and so on.

In some embodiments, the parameters adjusted by the system controller 1230 may be related to process conditions. Non-limiting examples include solution conditions (temperature, composition, and flow rate), and substrate position (rotation rate, linear (vertical) speed, angle from horizontal plane), etc. at different stages. These parameters can be provided to the user in the form of a recipe, which can be entered using the user interface.

The analog and / or digital input connections of the system controller 1230 can be used to provide signals from various process tool sensors to monitor the process. The signals used to control the process can be output on the analog and digital output connections of the process tool. Non-limiting examples of process tool sensors that can be monitored include: mass flow controllers, pressure sensors (eg, pressure gauges), thermocouples, optical position sensors, and so on. Properly programmed feedback and control algorithms can be used with data from these sensors to maintain process conditions.

In an embodiment of the multi-tool device, the instructions may include: inserting a substrate into a wafer holder, tilting the substrate, applying a bias voltage to the substrate during immersion, and electrodepositing a copper-containing structure on the substrate. These instructions may also include transferring the substrate to a removal tank, immersing the substrate in a stripping solution, rotating the substrate, and flowing the stripping liquid from the internal cross-flow manifold across the wafer surface (including: adjusting the flow rate, all or Part), and remove the substrate, clean the substrate, and dry the substrate.

The hand-off tool 1240 may select a substrate from a substrate cassette (such as the cassette 1242 or the cassette 1244). The cassette 1242 or the cassette 1244 may be front open wafer transfer cassettes (FOUPs). FOUP is a closed container designed to hold a substrate Reliably and securely housed in a controlled environment, and the tools are equipped with suitable load ports and robotic handling systems to allow the substrate to be moved for processing and measurement. The transfer tool 1240 may hold the substrate using a vacuum attachment device or some other attachment mechanism.

The transfer tool 1240 may interact with a wafer handling station 1232, a cassette 1242 or 1244, a transfer station 1250, or an aligner 1248. The transfer tool 1246 may retrieve the substrate from the transfer station 1250. The transfer station 1250 can be a groove or position, and the transfer tools 1240 and 1246 can pass the substrate back and forth to the groove or the position without passing through the aligner 1248. However, in some embodiments, to ensure that the substrate is properly aligned on the transfer tool 1246 for accurate transfer to a plating module, the transfer tool 1246 can align the substrate with the aligner 1248. The transfer tool 1246 can also transport the substrate to one of the plating modules 1202, 1204, or 1206, or one of the separated modules 1212, 1214, and 1216 for different process operations.

An apparatus for allowing a highly efficient circulating substrate to pass successive plating, cleaning, drying, and PEM process operations (such as peeling) is quite useful for implementations used in a manufacturing environment. In order to achieve such equipment, the module 1212 can be configured as a rotary washing and drying chamber, and an edge bevel removal chamber. With this module 1212, the substrate only needs to be transferred between the plating module 1204 and the module 1212 for copper plating and EBR operations. More than one internal portion of the device 1200 may be under subatmospheric pressure. For example, in some embodiments, the area surrounding all of the plating modules 1202, 1204, and 1206 and the PEMs 1212, 1214, and 1216 may be under vacuum. In other embodiments, only the area surrounding the plating bath is under vacuum. In a further embodiment, individual plating tanks can be under vacuum. Although the electrolyte fluid circuit is not shown in Figure 12 or 13, I can understand that the fluid circuit described herein can be implemented as part of (or in combination with) multiple tools.

FIG. 13 shows an additional example of a multi-tool device that can be used to implement the embodiments herein. In this embodiment, the electrodeposition apparatus 1300 has a set of electroplating baths 1307, each set of electroplating baths being contained in a pair or multiple pairs of plating baths. In addition to electroplating itself, the electrodeposition equipment 1300 can perform various processes and sub-steps related to electroplating, such as: spin cleaning, spin drying, wet etching of metals and silicon, electroless deposition, pre-wetting and pre-chemical treatment, reduction, annealing, Photoresist peeling and surface pre-activation. The electrodeposition equipment 1300 in the figure is schematically shown from top to bottom, and only a single level or "layer" is shown in the figure, but those skilled in the art can easily understand such equipment (such as: Lam Research Corporation of Fremont, CA's Sabre ^™ 3D tool) can have more than two levels stacked on top of each other, each of which can have the same or different kinds of processing stations.

Referring to FIG. 13 again, the substrate 1306 to be plated is generally fed to the electrodeposition equipment 1300 via a front-loading FOUP 1301, and in this example, the substrate is carried from the FOUP by the front-end robot 1302 to the main substrate of the electrodeposition equipment 1300 Processing area, the front-end robot can retrieve and move the substrate, and it is multi-dimensionally moved from one station of the accessible station to the other by the main shaft 1303 (shown as two front-end accessible stations 1304 in this example, And the other two front ends can access the station 1308) to be driven. The front-end accessible stations 1304 and 1308 may include, for example, a pretreatment station, a spin cleaning and drying (SRD) station. These stations 1304 and 1308 may also be removal stations as described herein. The robot track 1302a is used to achieve lateral movement from one side of the front-end robot 1302 to the other. Each base plate 1306 can be held by a cup / tapered component (not shown), which is driven by a spindle 1303 connected to a motor (not shown), and the motor can be connected to a mounting Bracket 1309. This example also shows four double plating tanks 1307 (that is, a total of eight plating tanks 1307). The plating bath 1307 can be used to electroplat copper for copper-containing structures, and electroplated solder (and other possible materials) for soldered structures. A system controller (not shown) may be connected to the electrodeposition apparatus 1300 to control the performance of part or all of the electrodeposition apparatus 1300. The system controller can be programmed or otherwise configured to execute instructions according to the process previously described herein.

The various hardware and method embodiments described above can be used in combination with lithographic patterning tools or processes used in the manufacture or production of semiconductor devices, displays, LEDs, solar panels, etc. Usually, though not necessarily, such tools / processes will be used together or implemented in a common manufacturing facility.

The electroplating equipment / method described above can be used in conjunction with lithographic patterning tools or processes, such as those used in the manufacture or production of semiconductor devices, displays, LEDs, solar panels, and the like. Usually, though not necessarily, such tools / processes will be used together or implemented in a common manufacturing facility. The lithographic patterning of a thin film usually includes some or all of the following steps (using some possible tools to perform each step): (1) using spin coating or spray tools to apply photoresist to the workpiece (ie, substrate ); (2) use a hot plate, furnace, or UV hardening tool to harden the photoresist; (3) use a tool like a wafer stepper to expose the photoresist to visible light, or UV light, or X-ray light; (4) use a tool like a wet bench to develop the photoresist to selectively remove the photoresist and thereby pattern the photoresist; (5) transfer by using a dry or plasma-assisted etching tool Photoresist Pattern into the underlying film or workpiece; and (6) use a tool such as an RF or microwave plasma resist remover to remove the resist.

Claims (27)

A method for electroplating a metal onto a substrate, the method comprising: flowing an electrolyte through a plating recirculation loop, the plating recirculation loop including an electrolyte storage tank, a pump, a plating tank, and a degasser, The degasser degass the electrolyte before the electrolyte is introduced into the plating tank; after the electrolyte is degassed and before the electrolyte is introduced into the plating tank, a gas is injected into the electrolyte; The substrate is immersed in the electrolyte in the plating bath, wherein the pressure in the plating bath during immersion is about 100 Torr or less; the material is plated on the substrate; and the substrate is removed from the electrolyte. For example, the method for plating a metal onto a substrate according to item 1 of the patent application, wherein the pressure in the plating bath during immersion is at least about 20 Torr. For example, the method for plating a metal onto a substrate according to item 1 of the patent application, wherein the step of immersing the substrate in the electrolyte occurs during a period of time of about 225 ms or less, and wherein the substrate has a diameter of about 150 mm or more. For example, a method for plating a metal onto a substrate according to item 3 of the patent application, wherein the step of immersing the substrate in the electrolyte occurs during a period of time of about 50 ms or less, and wherein the substrate has a diameter of about 150 mm or more. For example, the method for plating a metal onto a substrate according to item 1 of the patent application, wherein the step of immersing the substrate in the electrolyte occurs during a period of time having a first duration, and the material is plated to fill the substrate A feature step occurs during a time period having a second duration, and wherein the first duration is less than about 10% of the second duration. For example, the method for plating a metal on a substrate according to item 5 of the patent application, wherein the feature is a smallest feature on the substrate measured by volume. For example, the method for electroplating a metal onto a substrate according to item 5 of the application, wherein the feature is a medium-size feature on the substrate measured by volume. For example, the method for plating a metal onto a substrate according to item 1 of the application, wherein the substrate is immersed at an angle, and the substrate is swung in a horizontal direction at a swing speed of about 0.25-10 degrees / second. For example, the method for plating a metal onto a substrate according to item 1 of the scope of the patent application, wherein the pressure in the plating bath is maintained below about 100 Torr for at least 10 ms from the beginning of the plating. For example, the method for plating a metal onto a substrate according to item 9 of the scope of patent application, wherein the pressure in the plating tank is maintained below about 100 Torr until after the plating is stopped. For example, the method for plating metal onto a substrate according to item 1 of the patent application scope further includes inserting the substrate into a load lock chamber and reducing the pressure in the load lock chamber to less than about 100 Torr. For example, the method for electroplating a metal onto a substrate according to item 1 of the scope of the patent application, wherein the gas is oxygen, and the oxygen is injected to an electrolyte concentration of less than about 10 ppm. For example, the method for electroplating a metal onto a substrate according to item 12 of the application, wherein oxygen is injected to an electrolyte concentration of less than about 1 ppm. For example, the method for electroplating a metal onto a substrate according to item 1 of the scope of the patent application further includes flowing the electrolyte through a gas-controlled recirculation circuit. The gas-controlled recirculation circuit includes the electrolyte storage tank and a dissolved gas sensor. One of the dissolved gas controllers controls a gas injection unit according to the input from the dissolved gas sensor to adjust the dissolved gas concentration in the electrolyte. For example, the method for electroplating a metal onto a substrate according to item 14 of the application, wherein the electroplating recirculation circuit is separated from the gas control recirculation circuit. For example, the method for plating a metal onto a substrate according to item 1 of the patent application, wherein during the plating, the electrolyte bypasses the electrolyte storage tank of the electroplating recirculation circuit by a bypass duct. For example, the method for electroplating a metal onto a substrate according to item 1 of the scope of patent application further includes flowing the electrolyte through an atmospheric pressure recirculation circuit when the electroplating has not occurred, wherein the atmospheric pressure recirculation circuit includes the electrolyte storage tank and an atmospheric pressure. Electrolyte storage tank and atmospheric pressure circuit pump. For example, the method for electroplating a metal onto a substrate according to item 1 of the patent scope further includes degassing the electrolyte in a degassed electrolyte storage tank, and flowing the electrolyte through a degassing recirculation circuit and a Atmospheric pressure recirculation circuit, wherein the degassing recirculation circuit includes the electrolyte storage tank, a degassing circuit pump, and a degassed electrolyte storage tank, and wherein the atmospheric pressure recirculation circuit includes the degassed electrolyte storage tank and an atmospheric pressure circuit Pump, and a storage tank for atmospheric pressure electrolyte. An apparatus for electroplating a metal onto a substrate, the apparatus comprising: an electroplating tank configured to withstand a pressure lower than about 100 Torr, the electroplating tank including a substrate holder, an electrolyte storage tank, and a substrate positioning System, the substrate positioning system can control the direction of the substrate when the substrate is immersed in the electrolyte storage tank; a plating recycling circuit, the plating recycling circuit includes an electrolyte storage tank, a pump, a deaerator, and the A plating tank in which the deaerator is disposed after the electrolyte storage tank and in front of the plating tank in the plating recycling circuit; a gas injection unit; and a plating controller having instructions for: Through the electroplating recycling circuit, after the electrolyte is degassed and before the electrolyte is introduced into the electroplating tank, a gas is injected into the electrolyte from the gas injection unit, and the substrate is immersed in the electrolyte storage tank The electrolyte in the electrolyte, while maintaining a pressure of about 100 Torr or less in the electrolyte containing tank, plating the material onto the substrate, and removing the substrate from the electrolyte. For example, a device for electroplating a metal onto a substrate according to item 19 of the application, wherein the substrate positioning system can control the movement, tilt, and rotation of the substrate. For example, the device for electroplating a metal onto a substrate according to item 19 of the patent application scope further includes a dissolved gas sensor. For example, the apparatus for electroplating a metal onto a substrate according to item 21 of the patent application further includes a dissolved gas controller, wherein the dissolved gas controller controls the gas injection unit according to a measurement result from the dissolved gas sensor. For example, the equipment for electroplating a metal onto a substrate according to item 19 of the patent application further includes a bypass duct, wherein the electroplating controller is used to flow the electrolyte through the bypass duct during electroplating so as to bypass the bypass duct. Pass the electrolyte storage tank. For example, the equipment for electroplating a metal onto a substrate according to item 19 of the patent scope further includes an atmospheric pressure recirculation circuit including the electrolyte storage tank, an atmospheric pressure circuit pump, and an atmospheric pressure electrolyte storage tank. The electroplating controller is used to prevent the atmospheric pressure recirculation circuit from flowing during electroplating. For example, the equipment for electroplating a metal onto a substrate according to item 19 of the patent scope further includes a degassed electrolyte recycling circuit and a atmospheric pressure recycling circuit, wherein the degassed electrolyte recycling circuit includes the electrolyte storage tank , A pump, and a degassed electrolyte storage tank, and the atmospheric pressure recirculation circuit includes the degassed electrolyte storage tank, a pump, and an atmospheric pressure electrolyte storage tank, wherein the electroplating controller is used to ensure the degassed recycling There is no circulation of the circuit during plating. For example, the equipment for electroplating a metal onto a substrate according to item 19 of the scope of the patent application further includes an additional plating tank configured to operate below about 100 Torr, wherein the additional plating tank and the electrolytic The liquid storage tank is in fluid communication. A method for electroplating a metal onto a substrate, the method comprising: flowing an electrolyte through a plating recirculation loop, the plating recirculation loop including an electrolyte storage tank, a pump, a plating tank, and a degasser, The degasser degass the electrolyte before the electrolyte is introduced into the plating tank; the substrate is immersed in the electrolyte in the plating tank, wherein the pressure in the plating tank during immersion is below about 100 Torr; The material is electroplated onto the substrate, wherein during the electroplating, the electrolyte bypasses the electrolyte storage tank of the electroplating recirculation loop by a bypass conduit; and the substrate is removed from the electrolyte.