CN114369816A - Electroless plating tank, electroless plating system and electroless plating method - Google Patents

Abstract

An electroless plating bath, an electroless plating system including the same, and an electroless plating method using the same are provided. The chemical plating bath comprises a bath body and a rotatable bearing disc positioned in the bath body.

Description

Electroless plating tank, electroless plating system and electroless plating method

technical field

The present application relates to an electroless plating tank, an electroless plating system, and an electroless plating method.

Background technique

In order to provide more functionality, techniques are currently being developed to incorporate more than two semiconductor substrates in a semiconductor substrate package. In this technology, a semiconductor substrate may be stacked on another semiconductor substrate. In order to enable the signals of the two semiconductor substrates to communicate with each other, a bonding structure must be prepared between the two semiconductor substrates to electrically connect the two semiconductor substrates to each other. It is desired to prepare a good bonding structure, so that the semiconductor substrate package can perform its functions, and at the same time, the purpose of miniaturizing the semiconductor substrate package can be achieved.

SUMMARY OF THE INVENTION

In some embodiments, the present application provides an electroless plating bath. The electroless plating tank includes a tank body and a rotatable carrier plate located in the tank body.

In some embodiments, the present application provides an electroless plating system. The electroless plating system includes an electroless plating tank and one or more raw material tanks. The electroless plating tank includes a tank body and a rotatable carrier plate located in the tank body.

In some embodiments, the present application provides an electroless plating method. The method includes fixing an object to be plated on a rotatable carrier plate of an electroless plating tank; and injecting an electroless plating solution into the electroless plating tank to coat a metal layer on the object to be plated.

Description of drawings

Aspects of some embodiments of the present application are readily understood from the following detailed description when read in conjunction with the accompanying drawings. It should be noted that the various structures may not be drawn to scale and that the dimensions of the various structures may be arbitrarily increased or decreased for clarity of discussion.

1 illustrates a cross-sectional view of an electroless plating bath in accordance with some embodiments of the present application.

2 illustrates a cross-sectional view of an electroless plating bath in accordance with some embodiments of the present application.

3 illustrates a schematic diagram of an electroless plating system according to some embodiments of the present application.

4, 5, 6, and 7 illustrate various stages of an electroless plating method according to some embodiments of the present application.

FIG. 8 illustrates a joint structure according to some embodiments of the present application.

FIG. 9 illustrates a joint structure according to some embodiments of the present application.

10 and 11 illustrate bonding structures according to some comparative embodiments of the present application.

Shared reference numerals are used throughout the drawings and the detailed description to refer to the same or similar components. Embodiments of the present application will be readily understood from the following detailed description taken in conjunction with the accompanying drawings.

Detailed ways

The following disclosure provides many different embodiments or examples for implementing different features of the provided subject matter. Specific examples of components and arrangements are described below. Of course, these are only examples and are not intended to be limiting. In the present application, in the following description, reference to the formation or placement of a first feature over or on a second feature may include embodiments in which the first feature and the second feature are formed or placed in direct contact, and may also include additional features Embodiments that may be formed or positioned between the first feature and the second feature such that the first feature and the second feature may not be in direct contact. Additionally, this application may repeat reference numerals and/or letters in various instances. This repetition is for simplicity and clarity, and does not in itself prescribe the relationship between the various embodiments and/or configurations discussed.

Embodiments of the present application are discussed in detail below. It should be appreciated, however, that this application provides many applicable concepts that can be embodied in a wide variety of specific contexts. The specific embodiments discussed are illustrative only and do not limit the scope of the application.

The present application provides a novel electroless plating tank, an electroless plating system including the electroless plating tank, and an electroless plating method using the electroless plating tank. The electroless plating tank includes a tank body and a rotatable carrier plate located in the tank body. The object to be plated is placed on the rotatable carrier plate, and by rotating the rotatable carrier plate, the concentration of the plating solution can be made uniform, the thickness of the metal deposition can be uniform, and the gas can be discharged by centrifugal force. Therefore, the present application can prepare a bonding structure with good structure between two semiconductor substrates, and the obtained bonding structure has good reliability and electrical performance. Electroless plating is also called electroless plating. Compared with other prior art, the present application utilizes electroless plating to complete the metal bonding structure at a relatively low temperature.

1 and 2 illustrate cross-sectional views of an electroless plating bath 1 according to some embodiments of the present application.

Referring to FIG. 1 , the electroless plating tank 1 includes a tank body 10 and a rotatable carrier plate 11 located in the tank body. The top of the tank body 10 has an opening (not numbered in FIG. 1 ), and the electroless plating tank 1 further includes a cover body 15 . The cover body 15 is disposed on the top of the tank body 10 and closes the opening.

The electroless plating tank 1 further comprises one or more inlets 17 fluidly connected to the tank body 10 ; and one or more outlets 18 fluidly connected to the tank body 10 . In some embodiments, the inlet 17 can be disposed on the side wall of the tank body 10 , or disposed on the cover body as shown in FIG. 1 , and the electroless plating solution 20 can be injected into the electroless plating tank 1 through the inlet 17 . The outlet 18 can be arranged on the side wall or the bottom of the tank body 10 , and the waste plating solution after the reaction can be discharged to the outside of the electroless plating tank 1 through the outlet 18 .

The rotatable carrier plate 11 can be rotated continuously or in pulses, and can generate a stirring effect through the rotation, so that the concentration of the plating solution can be uniformed, so that the thickness of the metal deposition can be more uniform. In addition, centrifugal force can also be generated by rotation to discharge impurities or gases (for example, hydrogen generated by electroless plating reaction), so as to avoid impurities or gases remaining in the bonding structure and affecting the mechanical strength and electrical performance of the bonding structure. In some embodiments, the rotational speed of the rotatable carrier disc 11 is in the range of 0 to 300 rpm, for example, 0 rpm, 25 rpm, 50 rpm, 75 rpm, 100 rpm, 125 rpm, 150 rpm, 175 rpm, 200 rpm, 225 rpm, 250 rpm, 275 rpm or 300 rpm . In some embodiments, the electroless plating tank 1 includes a rotating shaft 13 , and the rotatable carrier plate 11 is fixed in the tank body through the rotating shaft 13 , and is continuously rotated or pulsed by the rotating shaft 13 . In some embodiments, the rotating shaft 13 is disposed at the center of the rotatable carrier plate 11 .

The rotatable carrier disc 11 may be a circular disc or other suitable shape. In some embodiments, the rotatable carrier plate 11 is a circular disk, which is beneficial to provide stable centrifugal force during rotation. In some embodiments, the rotatable carrier plate 11 has a bottom 111 and a side wall 112 , and the side wall 112 is disposed on the edge of the bottom 111 . In some embodiments, the sidewall 112 surrounds the edge of the bottom 111 . In some embodiments, the rotatable carrier plate 11 has one or more holding parts 16 for fixing the object to be plated 21, for example, two, three, four or more holding parts 16, the The holding member 16 can be disposed on the bottom 111 of the rotatable carrier plate 11 . In some embodiments, the holding member 16 can move according to the size of the object to be plated, so as to improve the holding effect and make the rotatable carrier plate 11 suitable for objects to be plated with different sizes.

The edge of the rotatable carrier plate 11 includes sacrificial electrodes 12 . The sacrificial electrode 12 can be independently disposed on the edge of the rotatable carrier plate 11 ; or disposed on the inner surface of the side wall 112 of the rotatable carrier plate 11 . In some embodiments, the sacrificial electrode 12 surrounds the edge of the rotatable carrier plate 11 . The sacrificial electrode can deposit or adsorb impurities on it, so as to prevent impurities from depositing on the inner sidewall of the tank body or dissociating in the plating solution and affecting the deposition effect. In some embodiments, the sacrificial electrode 12 is a material that is not easily corroded by acid or alkali, and impurities deposited or adsorbed thereon can be removed by cleaning. In some embodiments, the sacrificial electrode 12 comprises a noble metal (eg, platinum) or stainless steel. In some embodiments, the sacrificial electrode 12 may be mesh-shaped or sheet-shaped. In some embodiments, the sacrificial electrode 12 is detachable. When the deposit or adsorbate reaches a certain thickness, a new sacrificial electrode can be directly replaced to continue the electroless plating reaction, and the used sacrificial electrode 12 can be removed for further electroless plating. cleaning, so the cleaning and electroless plating efficiency can be improved. In some embodiments, when the rotatable carrier plate rotates, impurities move outward due to centrifugal force, and can be intercepted by the sacrificial electrodes disposed on the edge of the rotatable carrier plate 11 and deposited on the sacrificial electrodes , to avoid contamination of the entire electroless plating tank 1.

In some embodiments, the rotatable carrier plate 11 has an inclination angle with respect to the horizontal direction, so that the gas can be discharged from the electroless plating reaction place by gravity, so as to avoid the gas remaining in the bonding structure. In some embodiments, the inclination angle is greater than 0° and not greater than 60°, such as 3°, 5°, 10°, 15°, 20°, 25°, 30°, 35°, 40°, 45° °, 50°, 55° or 60°. In some embodiments, by making the bottom of the electroless plating tank 1 have an inclination angle with respect to the horizontal direction, the rotatable carrier plate 11 can have the inclination angle. For example, in some embodiments as shown in FIG. 2, the rotatable carrier plate 11 is configured adjacent to the bottom of the electroless plating tank 1 and is substantially parallel to the bottom of the electroless plating tank 1, the bottom of the electroless plating tank 1 and the The rotatable carrier plate 11 has an inclination angle θ with respect to the horizontal direction.

In some embodiments, by rotating the rotatable carrier plate 11 and making the rotatable carrier plate 11 have an inclination angle with respect to the horizontal direction, the centrifugal force and gravity can cooperate to improve the gas discharge effect.

FIG. 3 illustrates a schematic diagram of an electroless plating system 3 according to some embodiments of the present application.

Referring to FIG. 3 , the electroless plating system 3 includes an electroless plating tank 1 and one or more raw material tanks (eg, 31 , 32 , 33 and 34 ). The one or more raw material tanks are fluidly connected to the electroless plating tank 1 and are independently operable to inject the electroless plating solution stored in the raw material tanks into the electroless plating tank 1 . In some embodiments, the one or more raw material tanks may be selected from electroless copper sump 31 , electroless nickel sump 32 , electroless gold sump 33 and One or more of the electroless silver sump 34, but not limited thereto. The copper chemical collection tank 31 , the nickel chemical liquid collection tank 32 , the gold chemical liquid collection tank 33 and the silver chemical liquid collection tank 34 can provide corresponding chemical plating solutions. Metals such as copper, nickel, gold or silver are deposited on the object to be plated, and two metal structures opposite to the object to be plated are joined together by the deposited metal such as copper, nickel, gold or silver to form a joint structure, providing The electrical connection between the upper and lower sides of the object to be plated.

In some embodiments, the electroless plating system 3 may further include a waste liquid collection tank 35 and a cleaning liquid tank 36 . The raw material tanks 31 , 32 , 33 and 34 and the cleaning liquid tank 36 are connected to the inlet 17 of the electroless plating tank 1 through pipes. In some embodiments, one or more valves 25 (or a plurality of valves) can be arranged between the raw material tank and the cleaning liquid tank and the inlet 17 of the electroless plating tank 1 . The electroless plating solution is introduced into an electroless plating tank for electroless plating reaction, or a cleaning solution (such as deionized water) is introduced into a pipeline or an electroless plating tank for cleaning. In some embodiments, two or more chemical plating solutions may be used in sequence to perform the electroless plating reaction, and before changing the plating solutions, the cleaning solution is introduced into the electroless plating tank for cleaning, so as to avoid the occurrence of different chemical plating solutions. cause pollution. In addition, in some embodiments, one or more filter devices (not shown in FIG. 3 ) may be disposed between the raw material tank and the cleaning solution tank and the inlet 17 of the electroless plating tank 1 to inject the electroless plating solution into the electroless plating solution. Remove impurities in the plating solution before tank 1. The waste liquid collecting tank 35 is connected to the outlet 18 of the electroless plating tank 1 through a pipeline for collecting the waste plating liquid.

In some embodiments, the electroless plating system 3 may further include a pressure control device 26 . In some embodiments, the pressure control device 26 may provide a low pressure environment in an electroless plating bath. In some embodiments, the pressure control device 26 is a vacuum pump. The low pressure environment can promote the electroless plating solution in the electroless plating tank to flow toward the object to be plated 21 from all directions, so that the thickness of the obtained plated metal layer is more uniform. In addition, the gas generated by the electroless plating reaction can also be removed by the pressure control device (such as a vacuum pump), or even discharged from the electroless plating tank, thus further preventing the gas from remaining in the bonding structure and affecting the mechanical strength of the bonding structure and electrical performance.

In some embodiments, the electroless plating system 3 may further include a control device 37, a liquid pan 38, a flow meter 39a, a pressure gauge 39b, and other suitable devices. The control device 37 can independently control or set the temperature of each raw material tank and the electroless plating tank, the flow rate of the electroless plating solution, the rotational speed of the rotatable carrier plate, and the like. In some embodiments, the control device 37 is an electric control box. The flow meter 39a may be deployed at any suitable location (eg, at the inlet 17, or on individual pipes connected to each feed tank). The pressure gauge 39b can be arranged at any suitable location to monitor the pressure inside the electroless plating tank. The liquid holding tray 38 can be arranged below the chemical plating tank 1 , the raw material tanks 31 , 32 , 33 and 34 and the cleaning liquid tank 36 , so as to avoid leakage of liquid and pollute the working environment.

4, 5, 6, and 7 illustrate various stages of an electroless plating method according to some embodiments of the present application. 4 , 5 , 6 and 7 , in conjunction with FIG. 1 , will be described below.

4 and 5 illustrate the preparation of the object to be plated 21 .

Referring to FIG. 4, a first substrate 40 is provided. The first substrate 40 has a first patterned metal layer 41 . The first patterned metal layer 41 includes electrical connection structures (eg, metal pads, metal pillars or metal bumps)

Referring to FIG. 5, a second substrate 50 is provided. The second substrate 50 has a second patterned metal layer 51 , and the second patterned metal layer 51 has electrical connection structures (eg, metal pads, metal posts or metal bumps). The second substrate 50 is disposed above the first substrate 40, the second patterned metal layer 51 faces the first patterned metal layer 41, and the first patterned metal layer is second The electrical connection structure of the patterned metal layer 41 corresponds to the electrical connection structure of the second patterned metal layer 51 . One or more spacers 55 are disposed between the first substrate and the second substrate so that the first patterned metal layer 41 does not contact the second patterned metal layer 51 (ie, the first patterned metal layer 51 ). There is a distance between the upper surface of the electrical connection structure of a patterned metal layer 41 and the lower surface of the electrical connection structure of the second patterned metal layer 51 ) to complete the preparation of the object to be plated 21 . By adjusting the height of the spacer 55 , the distance between the corresponding electrical connection structures of the second patterned metal layer 51 and the first patterned metal layer 41 can be adjusted.

In the following, for the convenience of description, symbols 41 and 51 may be used to refer to the first patterned metal layer and the second patterned metal layer, or to the electrical connection structure of the first patterned metal layer and the second patterned metal layer. electrical connection structure.

Then, referring to FIG. 1 , the object to be plated 21 is fixed on the rotatable carrier plate 11 of the electroless plating tank 1; An electroless plating reaction is performed on the above, and a metal layer (refer to FIG. 6 , electroless metal layers 64 and 65 ) is plated on the object to be plated 21 by electroless plating (ie, electroless plating).

Referring to FIG. 6 , the electroless plating reaction can start after the object to be plated 21 is partially or completely immersed in the electroless plating solution 20 , and the metal ions in the electroless plating solution begin to deposit on the electrical connection structure of the first patterned metal layer. An electroless metal layer 64 is formed on the top and sidewalls of 41 , and an electroless metal layer 65 is formed on the bottom and sidewalls of the electrical connection structure 51 deposited on the second patterned metal layer. The electroless metal layer 64 and the electroless metal layer 65 gradually thicken with time, and are finally connected together, and are connected to the electrical connection structure of the first patterned metal layer and the electrical connection structure of the second patterned metal layer 41 and 51 together form a bonding structure 100 through which the first substrate 40 can be electrically connected to the second substrate 50 . The electroless metal layer 64 and the electroless metal layer 65 are made of the same material. In some embodiments, an interface exists where the electroless metal layer 64 and the electroless metal layer 65 are connected. In some embodiments, no interface exists or only an inconspicuous interface exists at the connection between the electroless metal layer 64 and the electroless metal layer 65 . In some embodiments, the bonding structure is made of metal, so it can also be called a metal bonding structure; in some embodiments, the bonding structure is an interconnection structure between two or more semiconductor substrates, so it can also be called a metal bonding structure. It is called a semiconductor junction structure.

In some embodiments, the first substrate 40 may be a wafer or a chip. In some embodiments, the second substrate 50 may be a wafer or a chip. For example, the object to be plated 21 shown in FIG. 5 and FIG. 6 includes a first substrate 40 and a second substrate 50 , and both the first substrate 40 and the second substrate 50 are wafers.

FIG. 7 illustrates a finished plated object 21 ′ in accordance with some embodiments of the present application relative to FIG. 6 . The object to be plated 21 ′ shown in FIG. 7 has a structure similar to that shown in FIG. 6 , however, in the object to be plated 21 ′ shown in FIG. 7 , the first substrate 40 is a wafer, the second substrate 50 a and the 50b is a chip.

Singulation may be performed after the joining structure 100 shown in FIG. 6 or FIG. 7 is completed.

FIG. 8 illustrates a joint structure 200 according to some embodiments of the present application. The bonding structure 200 includes upper and lower corresponding electrical connection structures 41 and 51 ; first electroless metallization layers 64 and 65 respectively plated on the electrical connection structures 41 and 51 ; and respectively plated on the first electroless metallization layers Second electroless metallization layers 66 and 66' of 64 and 65. The second electroless metallization layers 66 and 66' are connected together (ie, the upper surface of the second electroless metallization layer 66 is in contact or coplanar with the lower surface of the second electroless metallization layer 66'). The second electroless metallization layer and the first electroless metallization layer are composed of different materials. In some embodiments, the bonding structure 200 can be prepared by using different electroless plating solutions in sequence. For example, a first electroless plating solution can be injected into the electroless plating tank to electrically connect the structures 41 and 41 of the first patterned metal layer. First electroless metal plating layers 64 and 65 are respectively plated on the electrical connection structure 51 of the second patterned metal layer; and then a second electroless plating solution is injected into the electroless plating tank to deposit the first electroless metal plating on the first electroless metal plating layer. Layers 64 and 65 are plated with second electroless metal layers 66 and 66 ′, respectively. The second electroless metal layers 66 and 66 ′ are gradually thickened with time, and finally connected together with the first electroless metal layer 64 and 65, the electrical connection structure 41 of the first patterned metal layer and the electrical connection structure 51 of the second patterned metal layer together form the bonding structure 200, so that the first substrate 40 can be electrically connected to the bonding structure 200 the second substrate 50 .

Using different electroplating solutions to prepare a joint structure with two or more different electroplating metal layers can make the joint structure have multiple advantages (more excellent performance, relatively lower cost, etc.). For example, gold has excellent oxidation resistance and excellent electrical properties, but is expensive and has a slow deposition rate. Therefore, in some embodiments, a first plating solution containing an inexpensive and fast deposition rate metal (such as , copper) for the first electroless plating, depositing the first electroless plating metal layers 64 and 65 on the electrical connection structures 41 and 51, when the first electroless plating metal layers 64 and 65 reach a certain deposition thickness, switch to gold-containing The second electroless plating solution performs the second electroless plating, and the second electroless metal layers 66 and 66 ′ are deposited on the first electroless metal layers 64 and 65 to complete the bonding structure. Thereby, time and cost can be saved, and the resulting joint structure has excellent electrical properties and oxidation resistance.

FIG. 9 illustrates a joint structure according to some embodiments of the present application. Using the electroless plating tank, electroless plating system and electroless plating method according to the present application, a plurality of joint structures with uniform thickness of electroless metal layers can be provided between two substrates, and the obtained joint structure has less impurities and residual gas. As shown in FIG. 9 , the second substrate 50 is disposed above the first substrate 40 , the first substrate 40 has adjacent electrical connection structures 411 and 412 , and the second substrate 50 has adjacent electrical connection structures 511 and 512 . The distance between two adjacent electrical connection structures ( 411 and 412 , 511 and 512 ) is D1 . The electrical connection structure 411 corresponds to the electrical connection structure 511 , and the electrical connection structure 412 corresponds to the electrical connection structure 512 . The distance between the two opposite electrical connection structures ( 411 and 511 , 412 and 512 ) is H. Electroless metallization layers 641 and 651 are deposited on the first group of electrical connection structures 411 and 511 respectively, with a thickness of T1. Electroless metallization layers 642 and 652 are deposited on the second group of electrical connection structures 412 and 512 respectively, with a thickness of T2. Since the electroless plating tank of the present application is provided with a rotatable carrying plate, the object to be plated is placed on the rotatable carrying plate, and by rotating the rotatable carrying plate, the concentration of the electroless plating solution can be uniformized, and the electroless plating reaction can be generated. Therefore, electroless metal layers with relatively uniform thickness can be prepared at different positions (T1 and T2 are substantially the same, or only have a small difference), and the two connected electroless metal layers (641 and T2) in the joint structure 651, 642 and 652) no gas residue or only trace gas residue.

10 and 11 illustrate bonding structures according to some comparative embodiments of the present application. In the comparative example of FIG. 10 and FIG. 11 , a microfluidic device (not shown in the figure) is used to continuously inject the electroplating solution, and the electroplating solution enters the reaction tank (not shown in the figure) from the inlet 91 and passes through the object to be plated, and then flows toward the Outlet 92 flows. However, the direction of the flow field of this technology is relatively single, resulting in uneven thickness of the electroless metal layer plated with different positions.

As shown in FIG. 10, the deposition thickness T1 of the electroless metal layers (641 and 651) near the inlet 91 is greater than the deposition thickness T2 of the electroless metal layers (642 and 652) near the outlet 92, and there is a large difference between T1 and T2. When the first group of electrical connection structures 411 and 511 are bonded through the electroless metal layers 641 and 651 , the second group of electrical connection structures 412 and 512 have not yet been bonded, which will affect the electrical performance of the resulting semiconductor device structure. In order to complete the bonding of the second set of electrical connection structures 412 and 512 , the electroplating time must be prolonged.

As shown in FIG. 11 , after prolonging the electroless plating time, the deposition thickness of the electroless metal layers ( 641 and 651 ) near the inlet 91 increases to T3 , and the deposition thickness of the electroless metal layers ( 642 and 652 ) near the outlet 92 increases to T4 However, if the distance D1 between the two adjacent electrical connection structures ( 411 and 412 , 511 and 512 ) is too small, when the second set of electrical connection structures 412 and 512 are joined together, the deposition thickness of the electroless metal layer may be too high. thick, and the two adjacent electrical connection structures ( 411 and 412 , 511 and 512 ) are joined together, resulting in the risk of short circuit and poor reliability.

Compared with the comparative embodiments of FIGS. 10 and 11 , using the electroless plating tank, electroless plating system and electroless plating method according to the present application, a plurality of joint structures with uniform thickness of electroless metal layers can be provided between two substrates, even When the distance D1 between the two adjacent electrical connection structures ( 411 and 412 , 511 and 512 ) is reduced (eg, reduced to 16 μm or less), the two adjacent electrical connection structures are not joined together. Therefore, the electroless plating tank, electroless plating system and electroless plating method of the present application contribute to the goal of miniaturization. In addition, the microfluidic device used in the comparative example of FIGS. 10 and 11 is only suitable for metal docking between small-sized substrates, which is not conducive to mass production; the electroless plating tank, electroless plating system and electroless plating method of the present application are suitable for Metal butt joint to large size substrates to facilitate mass production.

For example "above", "below", "top", "left", "right", "bottom", "top", "bottom", "vertical", "horizontal", "side" unless otherwise specified , "above", "below", "upper", "above", "below", etc. spatial descriptions are indicated relative to the orientation shown in the figures. It should be understood that the spatial descriptions used herein are for illustrative purposes only and that actual implementations of the structures described herein may be spatially arranged in any orientation or manner, provided that the advantages of the embodiments of the present application are not Deviations from such arrangements will occur.

As used herein, the terms "approximately," "substantially," "substantially," and "about" are used to describe and explain small variations. When used in conjunction with an event or circumstance, the terms can refer to instances in which the event or circumstance occurs precisely as well as instances in which the event or circumstance occurs closely. For example, when used in conjunction with a numerical value, a term may refer to a range of variation less than or equal to ±10% of the numerical value, eg, less than or equal to ±5%, less than or equal to ±4%, less than or equal to ±3% , less than or equal to ±2%, less than or equal to ±1%, less than or equal to ±0.5%, less than or equal to ±0.1%, or less than or equal to ±0.05%. For example, if the first value is within a range of less than or equal to ±10% of the second value, such as less than or equal to ±5%, less than or equal to ±4%, less than or equal to ±3%, less than or equal to ± 2%, less than or equal to ±1%, less than or equal to ±0.5%, less than or equal to ±0.1%, or less than or equal to ±0.05%, then the first numerical value may be considered to be "substantially" the same as or equal to the second numerical value . For example, "substantially" vertical may refer to an angular variation range of less than or equal to ±10° relative to 90°, eg, less than or equal to ±5°, less than or equal to ±4°, less than or equal to ±3°, ±2° or less, ±1° or less, ±0.5° or less, ±0.1° or less, or ±0.05° or less.

Two surfaces may be considered coplanar or substantially coplanar if the displacement between the two surfaces is no greater than 5 μm, no greater than 2 μm, no greater than 1 μm, or no greater than 0.5 μm. A surface is considered substantially flat if the displacement between the highest and lowest points of the surface is no greater than 5 μm, no greater than 2 μm, no greater than 1 μm, or no greater than 0.5 μm.

As used herein, the singular terms "a/an" and "the" can include plural referents unless the context clearly dictates otherwise.

As used herein, the terms "conductive," "electrically conductive," and "conductivity" refer to the ability to carry electrical current. Conductive materials generally refer to those materials that exhibit little or zero resistance to current flow. One measure of electrical conductivity is Siemens/meter (S/m). Typically, a conductive material is a material with a conductivity greater than approximately 104 S/m (eg, at least 105 S/m or at least 106 S/m). The conductivity of a material can sometimes change with temperature. Conductivity of materials is measured at room temperature unless otherwise specified.

In addition, amounts, ratios, and other numerical values are sometimes presented herein in a range format. It is to be understood that such range formats are used for convenience and brevity, and are to be flexibly construed to include not only the values expressly stated as the limits of the range, but also all individual values or subranges subsumed within that range, as if expressly Each numerical value and subrange is specified generically.

While the present application has been described and illustrated with reference to specific embodiments thereof, these descriptions and illustrations are not intended to be limiting. It will be understood by those skilled in the art that various changes may be made and equivalents may be substituted without departing from the true spirit and scope of the application as defined by the appended claims. Illustrations may not necessarily be drawn to scale. Due to manufacturing processes and tolerances, there may be differences between the artistic reproduction in this application and the actual device. There may be other embodiments of the application not specifically described. The specification and drawings are to be regarded in an illustrative rather than a restrictive sense. Modifications may be made to adapt a particular situation, material, composition of matter, method or process to the object, spirit and scope of this application. All such modifications are intended to be within the scope of the appended claims. Although the methods disclosed herein have been described with reference to specific operations performed in a specific order, it is understood that these operations may be combined, subdivided, or reordered to form equivalent methods without departing from the teachings of the present application. Accordingly, unless specifically indicated herein, the order and grouping of operations are not limitations of the present application.

Claims (10)

1. An electroless plating bath comprising:

a trough body; and

a rotatable bearing disc positioned in the trough body.

2. The electroless plating bath according to claim 1 wherein the rotatable carrier plate has an oblique angle with respect to the horizontal.

3. The electroless plating bath of claim 1 wherein an edge of the rotatable carrier plate comprises a sacrificial electrode.

4. The electroless plating bath according to claim 1 wherein the rotatable carrier plate has a retaining feature.

5. The electroless plating bath of claim 1 wherein the sacrificial electrode surrounds the edge of the rotatable carrier plate.

6. An electroless plating system, comprising:

the electroless plating bath according to any of claims 1 to 5; and

one or more raw material tanks.

7. The electroless plating system of claim 6 wherein the one or more feedstock tanks are fluidly connected to the electroless plating tank and are independently operable to inject the electroless plating solution stored in the feedstock tanks into the electroless plating tank.

8. The electroless plating system of claim 6 further comprising a filtration device to remove impurities from the electroless plating solution prior to injection into the electroless plating tank.

9. The electroless plating system of claim 6 further comprising a pressure control device, the pressure control device being a vacuum pump.

10. The electroless plating system of claim 6 wherein the one or more feedstock reservoirs are selected from one or more of a copper plating reservoir, a nickel plating reservoir, a gold plating reservoir, and a silver plating reservoir.

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