Plating uniformity control by contact ring shaping

Mode of execution

According to some aspects of the invention, provided with a ring of a plurality of electrical contacts, to the processing system of the substrate for providing an electrical bias. The average thickness of the ring can be formed in the contact ring, the contact of the protrusions or "convex (scallop)" to increase. By compensating for the increase in the contact between the seed layer resistance, outstanding can help to control the contact between the change of the current density.

The terminology used here is that some proeminent ring generally refers to, or close to the contact thereof with respect to the contact between the contact (thinner) of the contact ring part has the thickness increased. For example, the convex can be formed on the bottom surface of the contact ring, under the electrical contact. Furthermore, in this use of the top and bottom are relative terms, is not limited to any particular orientation, generally refers to part away from the contact ring of the electroplating bath (top) or the contact ring of the electroplating bath-oriented part (bottom). In other words, upward plating surface of the substrate in a processing system, referred to here may be the top surface of the ring is the actual top-down.

Figure 1 according to one embodiment of the present invention has described an exemplary electrochemical plating (ECP) system 100 a perspective view and cross-sectional view part of the, electrochemical plating system 100 proeminent have utilized 156 contact ring 150. ECP system 100 generally includes a head assembly 102, substrate holding assembly 110 and the plating bath assembly 161. Head assembly 102 is carried by the support arm 106 is connected to the base 104. Head assembly 102 suitable for the plating bath assembly 161 the position of the above fixed assembly to the support substrate 110, its supporting a way that the head assembly 102 can be in the electroplating bath 165 positioning the substrate 120 (is fixed to the substrate fixing assembly ll0 in), to carry out the processing. Head assembly 120 is also suitable for the substrate 120 is put into the electroplating bath 165 before, during and after, to the substrate holding assembly 110 to provide a vertical movement, rotation and angular motion.

Electroplating trough module 161 generally includes an inner groove 167, contained in the greater diameter of the outer trough 163 inner. Any suitable technique can be used to the plating assembly 160 supply plating solution. For example, the electroplating solution can be through the inner bath 167 the inlet of the bottom surface 166 is supplied to the groove 167. The inlet 166 can be connected to the supply line, the supply line from the storage system, for example (not illustrated). Outer tank 163 recepting from the inner groove 163 of the liquid, and through the liquid discharge pipe 168 discharge of the collected liquid, discharge pipe 168 can also be connected to the electrolyte reservoir system.

An anode assembly 170 is positioned generally inside groove 163 in the lower region. The anode assembly 170 may be any suitable consumable or non-consumption type of anode. For certain embodiments, the diaphragm (not illustrated) generally across the diameter of the groove, located in anode assembly 170 above. The diaphragm can be any suitable type of diaphragm, such as a cation membrane, an anion membrane, uncharged film or multi-layer diffusion differentiated permeable membrane (  diffusion differentiated   permeable multi-layer). Can use any suitable method to the anode assembly 170 for providing an electrical connection.

For example, to the anode assembly 170 through the electrical connection of the anode electrode joint 174 provides. Anode electrode joint 174 can be made of any suitable conductive material, the conductive material is not dissolved in the plating liquid, for instance titanium , platinum and platinum painting stainless steel. As illustrated, the anode electrode joint 174 can extend through the plating bath assembly 161 of the bottom surface, and can be connected to the power supply (not illustrated) of the anode connector, for example, by any suitable wiring tube. The cathode of a power source connector can be connected to the contact ring 150, at the anode assembly 170 and the substrate 120 provide an electrical bias. In response to the anode assembly 170 and the substrate 120 plating surface 122 between the an electrical bias is applied, the current flux lines 180 in general the current from the anode assembly 170 to the substrate 120. The current flux lines 180 tend to the substrate 120 from the periphery of the. Therefore, the contact ring 150 may include a plurality of outstanding 156, which is generally formed in a plurality of contacts 154 below. Projection 156 can be used for the contact 154 or close to the contact 154 of control in the substrate 120 of the periphery of the current flux lines 180, efforts to control along the substrate 120 peripheral current density, such as the following, as will be described in more detail.

Substrate holding assembly

Substrate holding assembly 110 generally includes a means of connection elements 116 connected to the contact ring 150 of the mounting member 112. Connecting element 116 can fully interval in order to allow insertion of the substrate 120 (that is, the connecting element 116 of the interval may be greater than the substrate 120 of the diameter). Mounting member 112 can be via thrust plate assembly mounting plate 146, the substrate holding assembly 110 is connected to the head assembly 102. Substrate holding assembly 110 may lack other embodiments of mounting member 112, and may, for example, via the contact ring 150 is directly connected to the mounting plate 146. Mounting member 112, contact ring 150, and connection element 116 each can be coated with anti-plating material, for example PTFE material (such as Aflon^ or Tefzel^), or any other suitable plating-resistant coating material.

Contact ring 150 can make the substrate support surface 152 generally adapted to receive the substrate 120, the substrate plating surface 122 facing the plating bath 165. Substrate holding assembly 110 may also include a thrust plate 144, thrust plate is connected with the seal plate 142 generally suitable for the fixing force applied to the substrate 120 is, used for fixing the substrate 120 to the substrate support surface 152 on. Push plate reservoir 144 can be sufficient to ensure that the holding force placed on the sealing plate 142 of the annular sealing element 148 and the substrate of the non-plating surface 124 of the full seal between. In the case of note, because the contacts 154 engage the plating surface of the substrate 122, annular sealing element 148 can be suitable for the edge from the substrate substantially the same as the radial position of the contact substrate 120 of the non-plating surface 124. For certain embodiments, the substrate holding assembly 110 may include expandable bladder assembly (not illustrated), is suitable for exerting the same along the substrate 120 of the non-plating surface 124 the evenly distributed.

Push plate reservoir 144 is applied can also be sufficient to ensure the fixing of the substrate plating surface 122 and contact 154 the full electrical contact between, the contact 154 from the contact ring 150 of the substrate support surface 152 extends. Contact 154 generally suitable for electric contact substrate 120 of the plating surface 122, to the plating surface 122 to provide an electrical bias for electroplating. Contact 154 can be made of any suitable conductive material, such as copper (cu), platinum (Pt), tantalum (Ta), titanium (Ti), gold (Au), silver (Ag), stainless steel, its alloy or any other suitable conductive material.

As shown in Figure 2, the contacts 154 may be formed on protruding 156 above, is generally the same around the contact ring 150 of the substrate support surface 152 of the annular pattern. Contact 154 the number of variable, for example according to a substrate 120 (in fig. 2 is not displayed in) the change in size. Contact 154 also can be elastic so as to the height of the inconsistent contact non-plating surface. The (not-shown) through the power supply to the contact 154 power supply. Power supply can be used to all electrical contact 154 common power supply, to the electrical contacts 154 separately group or group of the power supply, or to the individual contacts 154 power supply. The current is supplied to the contact group or a single contact 154 embodiment, a current control system may be used to control pressure applied to each group or pin the current (pin).

For certain embodiments, the contact ring 150, the connecting element 116 and mounting member 112 is made from an electrically conductive material. And contact 154 the same, contact ring 150, the connecting element 116 and mounting member 112 can be made of suitable conductive material, and for certain embodiments, they can be made of stainless steel. According to this, the connecting element 116 may be electrically connected the mounting member 112 and the contact ring 150. Therefore, through the mounting member 112 and the power supply, one or more electrically connected to the contact 154 power supply.

Furthermore, for certain embodiments, the mounting member 112 of the thrust plate mounting plate 146 physical connection and the electrical connection, the mounting plate 146 also can be made of conducting material and is connected to the power supply. Mounting member 112 or mounting plate 146 can be via any suitable connection device is connected to the power supply, when the substrate holding assembly 110 is Figure 1 the head assembly 102 mobile (that is, lifting, dropping and rotating), the, device is suitable for connection to the contact 154 power supply.

As mentioned above, the seal plate 142 can be connected to the thrust plate 144. Thrust plate 144 is suitable for independent of the contact ring 150 mobile (upper or lower), in order to through the sealing element 148 non-electroplating the substrate exerts force on the surface, thereby fixing the substrate to the contact ring 150 of the substrate support surface 152. Sealing element 148 can be designed to offer the contact 154 and the substrate plating surface is between the contact force.

For example, the sealing element 148 can be made of flexible material, which is designed to reduce the sealing element 148 the effective spring constant. In other words, the sealing element 148 compressible to be suitable for non-plating surface of the substrate uniform slightly (or annular sealing element 148 of minor in the heterogeneous). For example, the sealing element 148 compressed, so the lowest point possible before the sealing, a relatively small sealing force of the highest point of the non-plating surface. Between the highest point and the lowest point reducing the difference, of the substrate on the surface of the non-plated partial strength , the substrate plating surface contact with the contact 154 on the local force can be more uniform. Contact 154 is more uniform force can lead to uniform the contact resistance and improved plating uniformity.

A plurality of outstanding 156 can be formed in a plurality of contacts 154 of the contact ring 150 on the bottom surface. Projection 156 of the size and the shape is not limited, and can be changed according to different application. For example, as shown in Figure 2, is formed on the contact 154 of the convex under 156 is basically rectangular shape. However, for other applications, the protruding can be other shapes, including, but not limited to, circular (such as a semi-cylinder or hemisphere) and the triangular (pyramid or serrated, for example). As illustrated, the protruding 156 can be from the contact ring 150 extending bottom surface of the (for example with the substrate support surface 152 relatively). However, for other embodiments, the protruding support surface can be from the substrate 152 extending, equivalent to lift the contact 154.

Figure 3A is a detailed cross-sectional view of the contact ring 150. As shown, contact ring 150 with contact 154 the thickness of the between t1, and the protruded 156 thickness of t2. Thickness t1 is from the substrate support surface 152 to the contact 154 the contact ring of the between 150 bottom surface 162 of the measured, and the thickness t2 is from the substrate support surface 152 of the contact ring to the contact 150 bottom surface 164 measured. Generally, as the t2 increase, the contact 154 or close to the contact 154 to reduce the current density, and the contacts 154 or close to the contact 154 of reduced galvanization quantity. Similarly, as the t1 reduced, increase of the current density between the contacts, and contact 154 to an increased plating between. By controlling the thickness t2 the t1 ratio, can make the current density is uniform, hence along the substrate 120 the periphery of the non-uniformity of the thickness of the plating can be reduced.

As shown, contact ring 150 of the plating-resistant coating 158 wrapped conductive core 160 is formed. For certain embodiments, the conductive core 160 can be a piece of solid electrically conductive material. Contact 154 can be from the plating surface 152 extends through the anti-plating coating 158. In order to maximize the plating surface 122 exposed to the surface area of the electroplating solution, contact 154 can be suitable for the periphery of the engaging or in close proximity with the periphery of the substrate 120 of the plating surface 122. For example, for different embodiments, contact 154 can be suitable for the substrate from the distance 120 edge less than 5 mm (for example, 2.5 mm or 4.5 mm) jointed at plating surface 122. As noted earlier, thrust plate assembly may include a sealing element (in Figure 3A did not display), the sealing element is adapted to be in and contact 154 the position of the diametrically opposite to the substrate 120 of the non-plating surface 124 exerts constant force, in order to against the contact ring 150 of the substrate support surface 152 fixed substrate 120. The contact can be suitable for the sealing element 154 and plating surface 122 provide a uniform sealing force between, it can help to provide a uniform contact resistance, this helps to provide around the plating surface 122 a uniform current.

As shown in Figure 3B shown, for certain embodiments, is connected to the contact ring 150 of the sealing element 130 can be suitable for from the electrical contact 154 to the mainland engaging substrate radial direction 120 of the plating surface 122. According to this, sealing element 130 can be a contact 154 shielding plating liquid flow, this can also contribute to provide a uniform contact resistance, for example, by preventing the contact 154 of the electroplating.

Plating surface 122 on any position of the current general and seed layer resistance, the contact resistance and electrode resistance inversely proportional to the sum. As mentioned above, the contact 154 of the plating surface 122 comparable the position of the the contact 154 or close to the contact 154 the position on the surface of the electroplating has a greater effective seed layer resistance. Seed layer resistance may lead to the increase of the current is reduced, as a result, contact 154 to reduce plating between. However, as shown in Figure 3C and 3D illustrated, the size of the more thick the protruding 156 is added between the contacts can be compensated the seed layer resistance, thus reducing along the plating surface 122 surrounding the change of the current.

Figure 3C is plating surface 122, and graph of current flux lines 180 extending to the contact 154 of under 3D shown the current flux lines 180 extending to the contact 154 of the plating surface 122. As shown, in either case, the flux lines 180 tend to along the contact ring 150 squeezing together, this effectively increases the effective resistance of the electroplating solution. However, since the projection 156 has increased thickness, therefore chart 3C in line of flux 180 bitu 3D in line of flux 180 squeezing together distance is long. According to this, the protruded 156 in the area between the, smaller effective resistance of the electroplating solution, this can be compensated when the contact 154 increased seed layer resistance between.

Figure 4A-B chart of the use of traditional separately with the contact ring and the contact ring of the uniformity of the plating. Each map is displayed with along the 40 nm of the seed layer 2 a 300 mm substrate sampling the peripheral of the plating thickness. Along the perimeter of the plating thickness is that of half of a quadrant (for example, 45 degrees) the sample. As shown, half of a quadrant may include 6 contacts, identified as pin in the Figure (that is, there are a total of 48 contacts). Figure 4A is the use of the sample substrate with approximately 7 mm uniform thickness (i.e., contact and the thickness of the contacts) of the conventional contact ring is plated. Figure 4B is the use of the sample substrate with the plating of the contact ring, the contact between the contact ring having a thickness of 5 mm (t1), the thickness of the under the contact 7 mm (t2). As shown in Figure 4A illustrated, the use of the traditional electric switches, electroplating thickness increase the contact or near contact, the contact is reduced. For example, electroplating thickness from the contact or near contact may be about 8000 angstroms changes to the position of the in between contact less than 6500 angstroms. On the contrary, as shown in Figure 4B shown, with a convex ring is used, only a small change in the thickness of the plating. Of course, for different embodiments and different application, possible changes in the actual plating uniformity.

According to this, both for different applications, the size and shape of the projection can be changed, in order to realize the optimum plating uniformity. For example, the thickness of the protruding ring between (t1) and the thickness of the ring (t2) can change based on different application parameters, such as the thickness of the seed layer, the desired thickness of the plating, the substrate size, intensity and an electrical bias, and so on of the material to be galvanized. In other words, increase t2 is to reduce in contact or close to the contact to the electroplating thickness, and reduce t1 is to increase contact between the necessary for the electroplating thickness. As shown in the example, for one embodiment, thickness t2 can be about 7 mm, and the thickness t1 can be about 5 mm. Thickness t2 (under the contact) typically in the 3 mm to 9 mm between, and the thickness t1 (in between contact) typically in the 1 mm to 5 mm between.

Contact ring manufacture

As mentioned above, uniform contact resistance also can to promote uniform plating thickness. Therefore, for certain embodiments, can be in accordance with the operation of the to ensure that uniform contact resistance of a contact ring is manufactured in a manufacturing process. Figure 5A-5F of the invention shown the basis for another embodiment, the different steps in the manufacturing process an example of the contact ring 550 a top (for example, support surface look down into the substrate).

For example, in Figure 5A in, contact ring 550 may include a monolithic conductive material 560 (e.g., stainless steel). By bonding a piece of contact material 570 to the contact ring 550 is, can be in the contact ring 550 is formed on the contact. Can be by any suitable bonding technique, such as soldering or welding the this piece of contact material 570 is bonded to the contact ring 550 on. (General, soldering when the melting point is lower than the 450 [...] of metal, and is higher than the melting point of the braze is the 450 [...] of metal. ) For certain embodiments, this piece of contact material 570 is bonded through brazing process. For example, this piece of contact material 570 may be placed in the formed in the contact ring 550 the hole 562 inner, contact material 570 in the top of cavity 562 on the top surface.

As shown in Figure 5B shown, one or a plurality of brazing material 572 can be adjacent contact material block 570 is placed in the cavity 562 in. Generally, brazing material 572 should also be the melting point of the conductive material 560 and the contact material 570 under the melting point of. Can also choose to have high corrosion resistance, high purity in order to avoid pollution, having a low vapor pressure at the brazing temperature and capable of wetting the contact material 570 and the conductive material 560 of the braze material 572. For example, for certain embodiments, contact material 570 can be a melting point approximately 2230 the of [...]platinum indium alloy (for example 85% platinum , 15% indium), and the conductive material 560 can be a melting point of approximately 1650 the stainless steel [...]. For brazing platinum indium alloy contact to the stainless steel contact ring (for example, with the above-mentioned nature) of appropriate brazing material 572 is one example of a melting point of approximately 1220 the [...] palladium cobalt alloy (for example, 65% of palladium, 35% cobalt). In other words, the contact ring 550 can be heated (such as in a furnace) to a temperature above the brazing material 572 the temperature of the melting point (for example higher than 1220 the [...]), lead to braze material 572 to melt and form the single braze material block 574, brazing material block 574 the contact material 570 is fixed to the contact ring 550, as shown in Figure 5C illustrated. The advantages of soldering the contact life cycle can include growth, more uniform and more uniform contact height of the contact resistance.

As mentioned above, general wish to maximize the surface area of the plating of the substrate. Therefore, for certain embodiments, the contact ring 550 of the inner ring part, by fig. 5D of said a dashed line, can be removed (e.g., cut) in order to prevent the removal of the part of the plating solution which can not be blocked from reaching the substrate, are formed and allows the contact of the contact close to the edge of the substrate plating surface of the substrate.

Figure 5E shown after the removal of the contact ring of the inner ring part 550. For certain embodiments, the plated material paints anti- 558 before the coating (shown in chart 5F in), contact ring 550 of the conductive material 560 surface can be processed in order to enhance the anti-plating material 558 to the contact ring 550 of adhesion. For example, the conductive material 560 surface may be sandblasted, this may change the conductive material 560 and enhanced the surface finish of the anti-plating material 558 of adhesion. Solidex can also prevent the plating-resistant material 558 as the time to slide over the contact material 570 top, this may hinder and plating surface of the substrate adequate electrical contact between contacts, thus increasing the contact resistance. Furthermore, for certain embodiments, the first coating material layer can be applied to the conductive material 560 surface, in addition or instead solidex surface, in order to enhance the anti-plating material 558 of adhesion.

Figure 5F shown in the coating of the anti-plating material 558 of the coating after final contact ring 550. As shown, contact material 570 through plating resistant material 558 coating is exposed, allowing the contact material 570 engaging substrate plating surface. For certain embodiments, the plated material paints anti- 558 before coating can cover the contact material 570, in order to prevent the anti-plating material 558 coating contact material. For other embodiments, the anti-plating material 558 coating can be applied to the contact material 570 on, and subsequently removing the.

Although the foregoing description is directed to the embodiment of the invention, but other of this invention and additional embodiments can be in the basic range not deviating from the derived under the condition of, and its range is the requirement of the rights attached.