This invention relates to the addition of a dual damascene pattern liner to the trenches or vias of the Back-End-Of-Line section of an integrated circuit.
The present invention is described with reference to the attached figures, wherein like reference numerals are used throughout the figures to designate similar or equivalent elements. The figures are not drawn to scale and they are provided merely to illustrate the instant invention. Several aspects of the invention are described below with reference to example applications for illustration. It should be understood that numerous specific details, relationships, and methods are set forth to provide a full understanding of the invention. One skilled in the relevant art, however, will readily recognize that the invention can be practiced without one or more of the specific details or with other methods. In other instances, well-known structures or operations are not shown in detail to avoid obscuring the invention. The present invention is not limited by the illustrated ordering of acts or events, as some acts may occur in different orders and/or concurrently with other acts or events. Furthermore, not all illustrated acts or events are required to implement a methodology in accordance with the present invention.
Referring to the drawings,
Immediately above the transistor is a layer of dielectric insulation 10 containing metal contacts 11 that electrically tie the transistor to the other logic elements (not shown) of the FEOL section 4. As an example, the composition of dielectric insulation 10 may be SiO2 and contacts 11 may comprise W.
The BEOL 5 contains a single damascene metal layer 12 and at least one dual damascene layer 13. Layers 12 and 13 contain metal lines, 14 and 15 respectively, that properly route electrical signals and power properly through the electronic device. Layer 13 also contains vias 16 that properly connect the metal lines of one metal layer (e.g. 14) to the metal lines of another metal layer (e.g. 15).
The single damascene metal layer 12 has metal lines 14 electrically insulated by dielectric material 17. As an example, the metal lines 14 may contain any metal such as copper and the dielectric material 17 may be any insulative material such as tetraethyl orthosilicate (TEOS). Furthermore, the single damascene metal layer 12 may have a thin dielectric layer 18 formed between the dielectric material 17 and the FEOL 4. It is within the scope of this invention to use any suitable material for the dielectric layer 18. For example, the dielectric layer 18 may comprise SiCN. The dielectric layer 18 may perform many functions. For example, dielectric layer 18 may function as a barrier layer; preventing the copper from interconnects 14 from diffusing to the silicon channel of the transistor or to another isolated metal line (thereby creating an electrical short). Second, dielectric layer 18 may function as an etch stop when manufacturing the metal lines 14 within the dielectric insulation material 17. Lastly, the dielectric layer 18 may function as an adhesion layer to help hold a layer of TEOS 17 to the FEOL 4 or to the dual damascene layer 13. For purposes of readability, the dielectric layer 18 will be called the barrier layer 18 during the rest of the description of this invention.
Referring again to
In accordance with the best mode of the present invention, the dual damascene layer 13 has a dual damascene pattern liner 21. The dual damascene pattern liner 21 is used during manufacturing (as described below) to ensure the proper formation of the metal lines 15 and 16. The dual damascene pattern liner 21 supports proper metal line formation because it facilitates proper trench patterning by protecting the photoresist from poisoning. It is within the scope of this invention to use one or more thin films to create the dual damascene pattern liner 21. Furthermore, it is within the scope of this invention to use any suitable material or layers of materials to create the dual damascene pattern liner 21. For example, either metal barrier films (such as TiSiN, TiN, or TaN) or dielectric barrier films (such as SiN, SiC, or SiON) may be used to create the dual damascene pattern liner 21. In the best mode application shown in
It is within the scope of this invention to use a dual damascene pattern liner 21 in any one of many configurations. For example, instead of using a dual damascene pattern liner 21 in one dual damascene layer 13, the dual damascene pattern liner 21 may be used in more than one consecutive or nonconsecutive dual damascene layers 13, 22, as shown in
An example variation of the dielectric layer for the dual damascene layer 13 is also shown in
Referring again to the drawings,
The present invention may be used in any integrated circuit configuration; therefore the first step is to fabricate the front-end section 4 (step 600) to create any logic elements necessary to perform the desired integrated circuit function. In addition, the single damascene metal layer 12 of the BEOL 5 is fabricated over the FEOL 4.
Referring now to
Next a low-k dielectric layer 19 is formed (step 602,
Now, a cap layer 25 is formed (step 602,
Step 604 starts with forming a bottom anti-reflection coating (“BARC”), over the cap layer 25, as shown in
Now the holes for the vias are etched using any well-known manufacturing process such as fluorocarbon-based plasma etch (step 606). In this example process the via hole is etched through the cap layer 25, the dielectric layer 19, and the dielectric layer 20. However, various via-first process flows are within the scope of this invention. For example, the dielectric layer 20 may not be etched at this time (rather it is etched in a later process). Or, a partial via etch may be performed (and then the via etch is completed in a later process). Once the via holes have been etched, the BARC 26 and photoresist 27 is removed by an ash process, resulting in the structure shown in
In the via-first process, the next step is to create the pattern for the trenches. However, applying a second layer of BARC and photoresist, and then developing the photoresist to create the trench pattern is problematic. After the via etch and ash (step 606) the dielectric layer 19 and possibly the barrier layer 20 is exposed inside the via pattern (see
In accordance with the invention, photoresist poisoning is eliminated by forming a dual damascene pattern liner 21 (step 608) over the substrate as shown in
Moreover, it is within the scope of this invention to use a range of thicknesses for the dual damascene pattern liner 21. Specifically, the dual damascene pattern liner 21 can be a thin as a monolayer or as thick as the pattern feature will allow. However, in the preferred application, the thickness of the dual damascene pattern liner 21 is approximately 5% of the pattern feature width.
Once the dual damascene pattern liner 21 is formed then the trenches are patterned. As shown in
In step 612 the trenches are etched using any well-known manufacturing process such as fluorocarbon-based plasma etch. If a trench stop layer was formed within the dielectric layer 19 then it is used to create the proper trench depth. Otherwise, the trench depth is controlled through manufacturing process techniques. Once the trenches have been etched then an ash process removes the BARC 26 and photoresist 27, resulting in the structure shown in
The dual damascene layer is completed by forming the metal trench 15 and via 16 structures. In the preferred application, the metal material is copper; however, the use of other metals such as aluminum or titanium is within the scope of this invention. In step 614 a layer of copper is formed over the substrate, as shown in
If the barrier layer 20 was not etched during via etch, then it will be etched during the trench etch process. Similarly, if a partial via etch was performed (as described above) then the via etch will be completed by etching remainder of the via and possibly the barrier layer 20 during the trench etch process. Moreover, the barrier layer 20 may be etched separately after either the trench etch process or the trench pattern ash process.
The structure of the integrated circuit at this point in the manufacturing process is shown in
Now the fabrication any remaining metal layers (such as layer 22 shown in
If a trench-first manufacturing process is used, then the trenches are patterned in step 604 and the trenches are etched in step 606. Next, the dual damascene pattern liner 21 is formed over the trench pattern, as shown in
In the trench-first manufacturing process the vias now are patterned and etched (steps 610 and 612). The structure at this point in the manufacturing process is shown in
Various modifications to the invention as described above are within the scope of the claimed invention. As an example, instead of using positive photoresist as described above, negative photoresist may be used. Instead of copper trenches 15 and vias 16, any electrically conductive material such as aluminum or titanium may be used. Similarly, instead of SiC the barrier material 18, 20 may be silicon nitride, silicon oxide, nitrogen-doped silicon carbide, or oxygen doped silicon carbide. In addition, it is within the scope of the invention to have a back-end structure 5 with a different amount or configuration of metal layers 12, 13 than is shown in
While various embodiments of the present invention have been described above, it should be understood that they have been presented by way of example only, and not limitation. Numerous changes to the disclosed embodiments can be made in accordance with the disclosure herein without departing from the spirit or scope of the invention. Thus, the breadth and scope of the present invention should not be limited by any of the above described embodiments. Rather, the scope of the invention should be defined in accordance with the following claims and their equivalents.
This is a division of application Ser. No. 10/430,558, filed May 6, 2003, the entire disclosure of which is hereby incorporated by reference.
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Number | Date | Country | |
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20040222529 A1 | Nov 2004 | US |
Number | Date | Country | |
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Parent | 10430558 | May 2003 | US |
Child | 10789338 | US |