Asymmetrical electrolytic plating for a conductive pattern

Abstract

The present invention relates to methods and systems for deposition of metal conductors using asymmetrical electrolytic plating, in which one surface (e.g., top) of a substrate is coated with an electrical conductor, and an opposite (e.g., bottom, or other) surface of which is not coated. A channel is formed between the two sides of the substrate, passing through the substrate and, in some embodiments, passing through the conductor. Electrolytic plating is performed such that metal is deposited from the edge of the conduct proximal to the channel, along the side walls of the channel, and up to, and in some embodiments on to, the other side of the substrate. Use of etching or plate resist layers are also contemplated.

Claims

1. A method of creating an electrically conductive via in a substrate having a first side and a second side, comprising the ordered steps of: creating a channel through the substrate; and using electrolytic plating to deposit a metal procedurally on the substrate, first from a conductor at a first region about the channel on the first side of the substrate, then along a wall of the channel, and then to a second region about the second side of the substrate; further comprising placing a plating resist onto a portion of the substrate, thereby further protecting the substrate from metal deposition, wherein the plating resist only inhibits metal deposition by electroless plating, and is a polymer.

2. The method of claim 1, wherein the conductor is coupled to the substrate prior to creating the channel.

3. The method of claim 1, wherein the conductor is coupled to the substrate after creating the channel.

4. The method of claim 1, wherein the step of creating the channel comprises removing a portion of the conductor.

5. The method of claim 1, wherein the channel does not extend entirely through the conductor.

6. The method of claim 1, further comprising placing an etching resist to protect a portion of the metal that had been plated to the first region, and then using an etching process to remove at least some of the metal not protected by the etching resist.

7. The method of claim 6, wherein the etching resist is selected from the group consisting of photoimagable and non-photoimagable polymer film, wax, metal, oligomer, and hardmask.

8. The method of claim 1, further comprising placing an etching resist to protect a portion of the metal that had been plated to the second region, and then using an etching process to remove at least some of the metal not protected by the etching resist.

9. The method of claim 1, wherein the substrate is selected from the group consisting of dielectric material ceramic, polymer and insulated metal.

10. The method of claim 1, wherein the metal is selected from the group consisting of gold, silver, nickel, copper, aluminum, lithium, iron, palladium, platinum, iridium, and corresponding alloys.

11. The method of claim 1, wherein the conductor is selected from the group consisting of gold, silver, nickel, copper, aluminum, lithium, iron, palladium, platinum, iridium, corresponding alloys and non-metals including carbon.

12. The method of claim 1, the channel is formed by photolithography technique or abrasion technique.

13. The method of claim 1, wherein the plating resist is selected from the group consisting of photoimagable and non-photoimagable polymer film, wax, oligomer, and hardmask.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 illustrates a cross-sectional view of steps in depositing metal along the sides of a channel using asymmetrical electrolytic plating, using an etching resist.

(2) FIG. 2 illustrates a cross-sectional view of metal deposition along the sides of a channel using asymmetrical electrolytic plating, using a plating resist.

(3) FIG. 3 illustrates a cross-sectional view of metal deposition along the sides of a channel using asymmetrical electrolytic plating, where an etching resist is deposited prior to the electrolytic plating.

(4) FIG. 4 illustrates a cross-sectional view of metal deposition along the sides of a channel using asymmetrical electrolytic plating, followed by electroless plating that uses both etching and plating resists.

(5) FIG. 5 illustrates a cross-sectional view of metal deposition along the sides of a channel using asymmetrical electrolytic plating, using an electroless metal deposition blocker.

(6) FIG. 6 illustrates a cross-sectional view of metal deposition into a channel using asymmetrical electrolytic plating, followed by the electroless plating.

DETAILED DESCRIPTION

(7) The inventive subject matter provides methods describing metal deposition along the sides of a channel formed within a dielectric substrate, using asymmetrical electrolytic plating. The metal deposition is formed on a dielectric substrate by electrolytic plating, starting from an end of the channel where the substrate is coated with an electrical conductor.

(8) FIG. 1 shows steps of a process 100 in which metal is deposited along the sides of the channel 130 using asymmetrical electrolytic plating. A substrate 110 is comprised of dielectric material and has a board structure. One surface (e.g., bottom surface) of the substrate 110 is coated by a layer of an electrical conductor 120 while the opposite surface (e.g., top surface) is not coated. The plating of an electrical conductor on substrate 110 is carried out by, for example, catalytic plating on a surface of the substrate 110, followed by electroless plating on the surface. A channel (hole) 130 is created in substrate 110, which includes channel 130 extending through electric conductor 120 as well as substrate 110. While FIG. 1 depicts forming a substrate with electrical conductor on one side and a channel passing through both the substrate and the electrical conductor, in some embodiments such are prefabricated, with the combination depicted in step A ready for additional processing

(9) Electrolytic plating is applied to substrate 110 (e.g., substrate placed in electrolytic bath), which causes metal deposition to grow from ends 140 of electrical conductor 120. As conductor continues to plate to ends 140 of electrical conductor 120, the conductor plates up interior walls 112 of substrate 110 (walls of channel 130) forming wall conductor 122, until it reaches the mouth of channel 130 forming conductor edge 141 (see steps B1 and B2). In some embodiments, electrolytic plating is continued further, which allows conductor to continue plating from conductor edge 141 and over the top surface of substrate 110, forming top conductor 142 (see step B2). In the two steps of B1 and B2, wall conductor 122 is deposited in a thin, even, and essentially vertical layer along the sides of the channel.

(10) Whether plating is stopped after conductor edge 141 is formed as in step B1, or allowed to continue and form top conductor 142 as in B2, the following steps C1 and C2 deposits an etching resist 160 over both mouths of channel 130, and covering portions of conductor 120, conductor edge 141, and top conductor 142 (step C2) proximal to channel 130. Steps D1 and D2 then apply either mechanical or chemical etching process to remove portions of conductor 120 and top conductor 142. In steps E1 and E2, etching resist 160 is removed (e.g., mechanically, chemically, thermally, light, etc), yielding substrate 110 with electroless plated conductor on the bottom surface, and thin electrolytic plated conductors vertically along the wall of channel 130, with conductor edge 141 (steps E1 and E2) or portions of top conductor 142 (step E2) on the top surface of substrate 110.

(11) FIG. 2 shows steps of another process 200 in which metal is deposited along the sides of a channel 230 using asymmetrical electrolytic plating. In step A, surface 212 (e.g., bottom surface) of substrate 210 is coated by a layer of electrical conductor 220, and the opposite surface 212 is not coated (e.g., top surface). Channel 230 is then formed through substrate 210 and conductor 220. In step B, a plating resist 270 is applied on opposite surface 212, except for rim surface 213 of opposite surface 212 proximal to channel 230. In step C, electrolytic plating is applied on substrate 210, which causes the metal deposition to start from the end 240 of the electrical conductor, and grow continuously up channel wall 214, and onto rim surface 213 of substrate 210, to the end 242 against, or immediately adjacent to, plating resist 270. In some embodiments, an etching resist 260 is applied about both ends of the channel to protect from etching in step D, either before or after removing plating resist 270 from substrate 210. Etching is performed in step E, which removes any conductor not protected or covered by etching resist 260. Etching resist 260 is removed in step F, leaving behind the conductor plated to the substrate. Viewed from another perspective, the process of FIG. 2 of FIG. 2 produces a substrate with a channel having thin electrolytic plated conductor extending from a conductor on the bottom surface of the substrate, vertically up the walls of a channel, and forming a thin conductor on the top surface of the substrate.

(12) FIG. 3 shows steps of another process 300 in which metal is deposited along the sides of a channel 330 using asymmetrical electrolytic plating. In step A, one surface (311) of substrate 310 is coated by a layer of an electrical conductor 320 and the other, opposing surface (312) is not coated. Channel 330 is then formed through substrate 310 and electrical conductor 320, for example by mechanical or laser methods. Etching resist 360 is then applied in step B on surfaces 311 and 312 about both ends of channel 330 and covering channel 330. Etching is performed in step C, removing portions of electrical conductor 320 from substrate surface 311 that were not protected by etching resist 360. After etching is performed, the etching resist is removed in steps D1 and D2, exposing wall surface 313 inside channel 330, substrate surfaces 311 and 312, and conductor portions 322 and 324 on surface 311.

(13) In some embodiments, electrolytic plating is then performed on the substrate 310, such that conductor deposition starts from conductor portions 322 and 324, extends along wall surface 313 of channel 330 in a thin line, and ultimately extending onto surface 312 the substrate (see step E1). As depicted, the electrolytic plating is terminated once the conductor deposition reaches a desired position on substrate surface 312, providing conductors 323 and 325 extending from substrate surfaces 311 and 312 across wall surface 313.

(14) In some embodiments, plating resist 370 is applied onto substrate surface 312, except for portions of surface 312 proximal to the opening of channel 330 (see step E2). The electrolytic plating is then performed, such that conductor deposition starts from conductor portions 322 and 324, extends along wall surface 313 of channel 330 in a thin line, and ultimately extending onto surface 312 the substrate (see step F). Conductor deposition ceases when the conductor meets or is immediately adjacent to plating resist 370. Plating resist is then removed in step G, leaving conductors 323 and 325 extending from substrate surfaces 311 and 312 across wall surface 313.

(15) FIG. 4 shows steps of another process 400 in which metal is deposited along the walls 413 of channel 430 using asymmetrical electrolytic plating. In step A, substrate 410 is plated with conductor 420 (e.g., via electroless or catalytic deposition) on side 411 (e.g., bottom side), and channel 430 is formed through substrate 410, having wall surface 413. In step B, electrolytic plating is performed, such that metal deposition starts from the end of conductor 420 proximal to channel 430, and extends along wall surface 413 toward substrate surface 412. Electrolytic deposition is ceased when the plated conductor is approximately flush with substrate surface 412. In step C, electroless plating is performed, such that additional conductor 480 is deposited on substrate surface 412. In step D, plating resist 470 is applied to the surface of conductor 480, leaving open a portion of conductor 480 proximal to channel 430. In step E, additional electrolytic plating is performed, increasing the deposit (e.g., depth, volume, etc) of conductor 480. In step F, plating resist 470 is removed, and etching resist 460 is applied on conductors 420 and 480 on surfaces 411 and 412 about both ends of channel 430 and covering channel 430. The portions of conductor 480 not covered by etching resist 460 are then etched away. Etching resist 460 is then removed in step F, leaving a substrate with thin line of conductor plated from one side of the substrate, along the walls of a channel in the substrate, and to the opposite side of the substrate.

(16) FIG. 5 shows steps of another process 500 in which metal is deposited along the sides of channel 530 using asymmetrical electrolytic plating. In step A, surface 511 (e.g., bottom) of substrate 510 is coated by a layer of electrical conductor 520, with surface 512 (e.g., top) coated by electroless blocker 590. In step B, channel 530 and trench 531 are created through the substrate and electroless blocker 590, with trench 531 crossing a mouth of channel 530 proximal to surface 512. The diameter and the depth of the trench 531 are greater and lesser than those of channel 530, respectively. In step C, electroless plating is performed to deposit conductor 580 along surface 513 of channel 530 and surface 514 of trench 531. In step D, electrolytic plating is applied to further deposit conductor along surface 513 of channel 530, and surface 514 of trench 531. Optional, electroless blocker 560 is then removed.

(17) FIG. 6 shows steps of another process 600 in which metal is deposited into channel 630 using asymmetrical electrolytic plating. In step A, surface 611 (e.g., bottom) of substrate 610 is coated by a layer of electrical conductor 620, and surface 612 (e.g., top) is coated by electroless blocker 690. In step B, blind channels 630a and 630b are formed through electroless blocker 690 and substrate 610 from surface 612 toward surface 611. Blind channels 630a and 630b do not penetrate conductor 620. Trench 631 is also formed across the mouths of blind channels 630a and 630b, proximal to surface 612 and electroless blocker 690. Preferably, the diameter and the depth of trench 631 are greater and lesser than those of blind channels 630a and 630b, respectively. In step C, conductor 622a and 622b is then plated or deposited inside channels 630a and 630b up to trench base 632, using at least one of electrolytic and electroless plating, preferably electrolytic plating. In step D, the surface of both substrate 610 and conductor 622a and 622b is further covered by conductor 680 via electroless plating. In some embodiments, additional conductor is deposited on top of conductor 680 by electrolytic plating to increase the layer of conductor (see step E).

(18) The discussion herein provides example embodiments of the inventive subject matter. Although each embodiment represents a single combination of inventive elements, the inventive subject matter is considered to include all possible combinations of the disclosed elements. Thus if one embodiment comprises elements A, B, and C, and an intermediate embodiment comprises elements B and D, then the inventive subject matter is also considered to include other remaining combinations of A, B, C, or D, even if not explicitly disclosed.

(19) As used herein, and unless the context dictates otherwise, the term “coupled to” is intended to include both direct coupling (in which two elements that are coupled to each other contact each other) and indirect coupling (in which at least one additional element is located between the two elements). Therefore, the terms “coupled to” and “coupled with” are used synonymously.

(20) Unless the context dictates the contrary, all ranges set forth herein should be interpreted as being inclusive of their endpoints, and open-ended ranges should be interpreted to include commercially practical values. Similarly, all lists of values should be considered as inclusive of intermediate values unless the context indicates the contrary.

(21) It should be apparent to those skilled in the art that many more modifications besides those already described are possible without departing from the inventive concepts herein. The inventive subject matter, therefore, is not to be restricted except in the scope of the appended claims. Moreover, in interpreting both the specification and the claims, all terms should be interpreted in the broadest possible manner consistent with the context. In particular, the terms “comprises” and “comprising” should be interpreted as referring to elements, components, or steps in a non-exclusive manner, indicating that the referenced elements, components, or steps may be present, or utilized, or combined with other elements, components, or steps that are not expressly referenced. Where the specification claims refers to at least one of something selected from the group consisting of A, B, C . . . and N, the text should be interpreted as requiring only one element from the group, not A plus N, or B plus N, etc.