Method of Manufacturing a Component Carrier Metal Trace and a Component Carrier

Abstract

A method for manufacturing a component carrier includes i) providing a metal layer, in particular a copper layer; ii) forming a film on the metal layer; iii) patterning the film in order to expose a part of the metal layer; iv) carrying out a first etch, thereby thinning the film and removing a further part of the exposed metal layer; and thereafter v) carrying out a second etch, thereby forming at least one metal trace that is spatially separated from the metal layer. A component carrier made by the method is further described.

Claims

1. A method of manufacturing a component carrier, the method comprising: providing a metal layer; providing a film on the metal layer; patterning the film in order to expose an area of the metal layer; carrying out a first etch, thereby removing a part of the exposed metal layer and maintaining a thickness of the film; and thereafter carrying out a second etch, thereby forming at least one metal trace that is spatially separated from the metal layer.

2. The method according to claim 1, wherein forming the at least one metal trace further comprises: forming a first cavity in the metal layer by the first etch and the second etch, and forming a further cavity in the metal layer by the first etch and the second etch, such that the metal trace is located between the first cavity and the further cavity.

3. The method according to claim 1, wherein the area of the metal layer where the first etch and the second etch are carried out further comprises at least two adjacent sub-areas on one of the component carrier main surfaces, wherein said at least two sub-areas are provided at a distance from each other to form the metal trace.

4. The method according to claim 1, wherein the first etch comprises a wet etch or a dry etch.

5. The method according to claim 1, wherein the second etch comprises a wet etch or a dry etch.

6. The method according to claim 1, wherein the film is resistant to the second etch; and/or wherein the film is not resistant to the first etch.

7. The method according to claim 1, wherein the film is thinned during carrying out the first etch.

8. The method according to claim 7, further comprising: removing part of the film, and thereby enlarging the exposed area of the metal layer.

9. The method according to claim 1, wherein the first etch and/or the second etch is an isotropic etch comprising an isotropic etchant.

10. The method according to claim 1, wherein patterning the film comprises: forming at least one exposed area in the film, wherein the sidewalls of the at least one exposed area taper towards the metal layer.

11. The method according to claim 10, wherein forming the film comprises: laminating the film onto the metal layer.

12. The method according to claim 10, wherein forming the film comprises: providing the film with a thickness of 12 μm or more.

13. The method according to claim 1, wherein maintaining the thickness comprises: thinning the film to a thickness of 90% or lower of the initial thickness.

14. The method according to claim 1, wherein the film is a dry film or a wet film.

15. The method according to claim 1, wherein the method further comprises: removing the film after the second etch.

16. The method according to claim 1, wherein the metal layer has a thickness of 30 μm or more.

17. The method according to claim 1, further comprising: forming a further metal trace next to the metal trace, such that the metal trace and the further metal trace are arranged side-by-side with a bottom-sided spacing in between.

18. The method according to claim 17, further comprising at least one of the following features: wherein the area of the metal trace, where the first etch and the second etch are carried out, comprises more than two adjacent sub-areas on one of the component carrier main surfaces, wherein said more than two sub-areas are provided at a distance from each other, so that, after the first and the second etch, at least two adjacent metal traces between the sub-areas are formed side-by-side; wherein the sub-areas are arranged with a bottom-sided spacing in between; wherein, after the second etch, each of the at least two metal traces has a bottom-sided line width of 40 μm or less; wherein, after the second etch, at least two adjacent metal traces are spaced by the bottom-sided spacing of less than 45 μm; wherein, after the second etch, each of the at least two adjacent metal traces has a top-sided line width in the range 80% to 100% of its corresponding bottom-sided line width; wherein, after the second etch, each of the adjacent metal traces has a thickness of at least 30 μm.

19. A component carrier, comprising: a stack having at least one electrically conductive layer structure and at least one electrically insulating layer structure; wherein the at least one electrically conductive layer structure comprises a metal trace and a further metal trace arranged side by side; wherein each of the metal trace and the further metal trace has a bottom-sided line width of 40 μm or less; wherein the metal trace and the further metal trace are spaced by a bottom-sided spacing of 45 μm or less; wherein each of the metal trace and the further metal trace has a top-sided line width of at least 80% of its respective bottom-sided line width; and wherein each of the metal trace and the further metal trace has a vertical thickness of 30 μm or more.

20. The component carrier according to claim 19, wherein the metal trace and/or the further metal trace comprises an etching factor of 3 or more.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0064] FIG. 1 shows a component carrier according to an exemplary embodiment of the disclosure.

[0065] FIG. 2A, FIG. 2B, FIG. 2C and FIG. 2D illustrate a method of manufacturing a component carrier according to an exemplary embodiment of the disclosure.

[0066] FIG. 3A, FIG. 3B, and FIG. 3C illustrate a method of manufacturing a component carrier according to another exemplary embodiment of the disclosure.

[0067] FIG. 4 illustrates a definition of the etching factor.

DETAILED DESCRIPTION OF ILLUSTRATED EMBODIMENTS

[0068] The illustrations in the drawings are schematically presented. In different drawings, similar or identical elements are provided with the same reference signs.

[0069] FIG. 1 shows a component carrier 100 according to an exemplary embodiment of the disclosure. The component carrier 100 comprises a stack (not shown in detail) having at least one electrically conductive layer structure 110 and at least one electrically insulating layer structure 102. The electrically insulating layer structure 102 is configured as a base substrate 115, e.g., of FR4 material. The electrically conductive layer structure 110 comprises, e.g., a metal trace 130 and a further metal trace 131 arranged side by side with a bottom-sided spacing S in between. Each metal trace 130, 131 comprises a bottom-sided line width L1 and a top-sided line width L2. The bottom-sided line width L1 is for both metal traces 130, 131 less than 40 μm (in the example shown 35 μm). The bottom-sided spacing S is not more than 50 μm, in the example shown 40 μm. The top-sided line width L2 is for both metal traces 130, 131 in the range 80% to 100% of its corresponding bottom-sided line width L1, in the example shown 35 μm. Further, each of the metal traces 130, 131 has a vertical thickness (along the z-axis) of more than 30 μm, in the example shown 35 μm. It can be further calculated (see FIG. 4) that the metal trace 130 and the further metal trace 131 respectively comprises an etching factor of more than 14.

[0070] FIGS. 2A to 2D show a method of manufacturing a component carrier 100 according to an exemplary embodiment of the disclosure.

[0071] In FIG. 2A there is provided a metal layer 110, in this example a thick copper layer (e.g., 36 μm thickness) on an electrically insulating substrate 115, 102. An electrically insulating dry film 120, being a photoresist, is covered (laminated onto) the metal layer 110. Further, the film 120 is patterned (e.g., by photolithography) in order to expose a part 111 of the metal layer 110. In other words, by forming exposed areas (with sidewalls 125) in the film 120, the part(s) of the metal layer 120 below the holes will be exposed.

[0072] In FIG. 2B there is carried out a first etch which removes a further part 112 (which includes the part 111) of the exposed metal layer 110. By removing the further part(s) 112 of the metal layer 110, a cavity 140 and a further cavity 141 are formed in the metal layer 110.

[0073] In FIG. 2C the first etch is a dry etch or wet etch (e.g., a plasma etch, in particular a descum etch), to which the film 120 is not resistant. Thus, the first etch thins the film 120, removes part of the film 120 (and a further part 112 of the metal layer 110). In an example, the film 120 is thinned from a vertical thickness of more than 12 μm, in particular more than 14 μm to 10 μm or less, in particular 8 μm or less. As can be seen in FIG. 2C, a part of the film 120, which covers a metal layer main surface at the tops of the cavity 140 and the further cavity 141, is also removed. Thereby, the upper main surface of the metal layer 110 is exposed around the openings of the cavity 140 and the further cavity 141.

[0074] As illustrated in FIG. 2D, thereafter, it is carried out a second etch which enlarges the cavity 140 and the further cavity 141, so that a metal trace 130 is formed between the cavity 140 and the further cavity 141. Hereby, the entire metal plate thickness is removed in this area. In this manner, the formed metal trace 130 is spatially separated (by the cavity 140 and the further cavity 141) from the (rest of the) metal layer 110. The second etch comprises a wet etch (in particular using an isotropic etchant such as copper chloride) or a dry etch. Hereby, the film 120 is resistant to the second etch.

[0075] The metal trace 130 is still covered by a part of the film 121. The metal layer 110 is also still covered by the respective film parts 120. In a further step, however, the film 120, 121 can be removed (not shown).

[0076] FIGS. 3A to 3C show a method of manufacturing a component carrier 100 according to another exemplary embodiment of the disclosure. The method is very similar to the one described in FIGS. 2A to 2D above. The difference being that, during patterning of the film 120, sidewalls 125 of the holes in the film 120 are formed such that the film sidewalls 125 taper, with respect to the cavity 140 and the further cavity 141, towards the cavity 140 and the further cavity 141 (and to the metal layer 110). The angles of the sidewalls 125 with respect to the upper main surface of the metal layer 110 are preferably in the range 20 to 70°, more preferably around 60°.

[0077] In FIG. 3A during patterning of the film 120, holes are formed in the film 120 and the sidewalls 125 of the holes taper with respect to the cavity 140 and the further cavity 141. During the first etch, the cavity 140 and the further cavity 141 are formed.

[0078] In FIG. 3B further, during the first etch, the film 120 is thinned (a part 122 in the vertical thickness is removed). This thinning or removal also takes place at the tapering sidewalls 125.

[0079] In FIG. 3C there is performed the second etch which enlarges the cavity 140 and the further cavity 141, so that a metal trace 130 is formed between the cavity 140 and the further cavity 141. The film 120 is resistant to the second etch, so that the respective tops of the cavity 140 and the further cavity 141 are partially covered by the film 120 (and the tapering sidewalls 125).

[0080] FIG. 4 illustrates the definition of the etching factor (EF) that can be used to validate the quality of a (etched) metal trace. After etching a metal layer, an etched (trapezoidal) metal trace 130 can be described by the etching factor EF as follows: two times the line thickness (Thk, height) divided by the line width top (TW or L2) subtracted from the line width bottom (BW or L1): EF=(2*Thk)/(BW−TW). For example, an etching factor of three or more, in particular five or more, may be considered as accurate, depending on the manufacture circumstances.

[0081] It should be noted that the term “comprising” does not exclude other elements or steps and the article “a” or “an” does not exclude a plurality. Also, elements described in association with different embodiments may be combined.

[0082] Implementation of the invention is not limited to the preferred embodiments shown in the figures and described above. Instead, a multiplicity of variants are possible which variants use the solutions shown and the principle according to the invention even in the case of fundamentally different embodiments.

REFERENCE SIGNS

[0083] 100 Component carrier

[0084] 102 electrically insulating layer structure

[0085] 110 Metal layer

[0086] 111 Area of metal layer

[0087] 112 Part of metal layer

[0088] 115 Substrate, electrically insulating layer structure

[0089] 120 Film, film part

[0090] 121 Further film part

[0091] 122 Removed film part

[0092] 125 Tapering sidewalls

[0093] 130 Metal trace

[0094] 131 Further metal trace

[0095] 140 First cavity

[0096] 141 Second/further cavity

[0097] L1 Bottom-sided line width

[0098] L2 Top-sided line width

[0099] S Bottom-sided spacing