PRECUT METAL LINES
Embodiments of the present invention provide a method for cuts of sacrificial metal lines in a back end of line structure. Sacrificial Mx+1 lines are formed above metal Mx lines. A line cut lithography stack is deposited and patterned over the sacrificial Mx+1 lines and a cut cavity is formed. The cut cavity is filled with dielectric material. A selective etch process removes the sacrificial Mx+1 lines, preserving the dielectric that fills in the cut cavity. Precut metal lines are then formed by depositing metal where the sacrificial Mx+1 lines were removed. Thus embodiments of the present invention provide precut metal lines, and do not require metal cutting. By avoiding the need for metal cutting, the risks associated with metal cutting are avoided.
The present invention relates generally to semiconductor fabrication, and more particularly, to precut metal lines.
BACKGROUNDAs the fabrication techniques for semiconductor devices has progressed, manufacturers have been placing an increasingly larger number of devices on a chip by increasing the integration density of semiconductor devices. Accordingly, a critical dimension (CD) in a design rule is gradually reduced in order to increase the circuit density.
In order to increase the circuit density, it is necessary to reduce the sizes of elements inside the semiconductor devices and reduce the lengths and widths of interconnections which couple the elements together. Moreover, the resistances of interconnections must be small so that electric signals can be transferred with minimal loss within the semiconductor devices through interconnections having narrow widths.
In a typical integrated circuit, there may be many metallization layers and interconnecting via layers formed in a back end of line (BEOL) interconnect structure. The BEOL interconnect structure connects various devices (e.g. transistors, capacitors, etc.) to form functional circuits. During fabrication, it is necessary to form cuts and connections of metal lines to create the desired connectivity to implement a given design. As critical dimensions continue to shrink, this can be challenging. It is therefore desirable to have improvements to address the aforementioned challenges.
SUMMARYEmbodiments of the present invention provide a method for cuts of sacrificial metal lines in a back end of line structure. Sacrificial Mx+1 lines are formed above metal Mx lines. A line cut lithography stack is deposited and patterned over the sacrificial Mx+1 lines and a cut cavity is formed. The cut cavity is filled with dielectric material. A selective etch process removes the sacrificial Mx+1 lines, preserving the dielectric that fills in the cut cavity. Precut metal lines are then formed by depositing metal where the sacrificial Mx+1 lines were removed. Thus, embodiments of the present invention provide precut metal lines, and do not require metal cutting. By avoiding the need for metal cutting, the risks associated with metal cutting are avoided.
In a first aspect, embodiments of the present invention provide a method of forming a semiconductor structure, comprising: forming a plurality of sacrificial Mx+1 lines over a plurality of metal Mx lines; depositing a dielectric layer over the plurality of sacrificial Mx+1 lines; forming a cut cavity in one sacrificial Mx+1 line of the plurality of sacrificial Mx+1 lines; forming a dielectric region in the cut cavity; removing the plurality of sacrificial Mx+1 lines to form a plurality of Mx+1 line cavities; and filling the plurality of Mx+1 line cavities with a metal to form a plurality of metal Mx+1 lines.
In a second aspect, embodiments of the present invention provide a method of forming a semiconductor structure, comprising: forming a plurality of sacrificial Mx+1 lines over a plurality of metal Mx lines; depositing a dielectric layer over the plurality of sacrificial Mx+1 lines; depositing an organic planarization layer on the dielectric layer; depositing a resist layer on the organic planarization layer; forming a cavity in the resist layer and organic planarization layer; removing the resist layer; depositing a conformal spacer layer on the organic planarization layer; performing an anisotropic etch on the conformal spacer layer to form an aperture spacer; forming a cut cavity in one sacrificial Mx+1 line of the plurality of sacrificial Mx+1 lines; forming a dielectric region in the cut cavity; removing the plurality of sacrificial Mx+1 lines to form a plurality of Mx+1 line cavities; and filling the plurality of Mx+1 line cavities with a metal to form a plurality of metal Mx+1 lines.
In a third aspect, embodiments of the present invention provide a method of forming a semiconductor structure, comprising: forming a plurality of sacrificial Mx+1 lines over a plurality of metal Mx lines; depositing a dielectric layer over the plurality of sacrificial Mx+1 lines; forming a cut cavity in one sacrificial Mx+1 line of the plurality of sacrificial Mx+1 lines; forming a dielectric region in the cut cavity; removing the plurality of sacrificial Mx+1 lines to form a plurality of Mx+1 line cavities; depositing a via cut lithography stack; patterning an opening in the via cut lithography stack; forming a via cavity that exposes one Mx metal line of the plurality of metal Mx lines; removing the via cut lithography stack; and filling the plurality of Mx+1 line cavities and via cavity with a metal to form a plurality of metal Mx+1 lines and a via.
The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate several embodiments of the present teachings and, together with the description, serve to explain the principles of the present teachings.
Certain elements in some of the figures may be omitted, or illustrated not-to-scale, for illustrative clarity. The cross-sectional views may be in the form of “slices”, or “near-sighted” cross-sectional views, omitting certain background lines which would otherwise be visible in a “true” cross-sectional view, for illustrative clarity.
Often, similar elements may be referred to by similar numbers in various figures (FIGs) of the drawing, in which case, typically the last two significant digits may be the same, the most significant digit being the number of the drawing figure (FIG). Furthermore, for clarity, some reference numbers may be omitted in certain drawings.
Exemplary embodiments will now be described more fully herein with reference to the accompanying drawings, in which exemplary embodiments are shown. It will be appreciated that this disclosure may be embodied in many different forms and should not be construed as limited to the exemplary embodiments set forth herein. Rather, these exemplary embodiments are provided so that this disclosure will be thorough and complete and will fully convey the scope of this disclosure to those skilled in the art.
The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of this disclosure. For example, as used herein, the singular forms “a”, “an”, and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. Furthermore, the use of the terms “a”, “an”, etc., do not denote a limitation of quantity, but rather denote the presence of at least one of the referenced items. It will be further understood that the terms “comprises” and/or “comprising”, or “includes” and/or “including”, when used in this specification, specify the presence of stated features, regions, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, regions, integers, steps, operations, elements, components, and/or groups thereof.
Reference throughout this specification to “one embodiment,” “an embodiment,” “embodiments,” “exemplary embodiments,” or similar language means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention. Thus, appearances of the phrases “in one embodiment,” “in an embodiment,” “in embodiments” and similar language throughout this specification may, but do not necessarily, all refer to the same embodiment.
The terms “overlying” or “atop”, “positioned on” or “positioned atop”, “underlying”, “beneath” or “below” mean that a first element, such as a first structure, e.g., a first layer, is present on a second element, such as a second structure, e.g. a second layer, wherein intervening elements, such as an interface structure, e.g. interface layer, may be present between the first element and the second element.
A plurality of voids 124 are patterned in the lithography stack 122. The voids 124 each expose a region of a sacrificial line 116, as well as some of the dielectric region 118. The dielectric layer 118 and the sacrificial lines 116 are comprised of different materials, allowing selective etch techniques to remove the portions of the sacrificial lines 116 that are exposed through the voids 124, without removing the exposed dielectric regions 118. Thus, the tolerances of the position and sizing of each void 124 is relaxed, enabling easier manufacturing and improved product yield.
While the invention has been particularly shown and described in conjunction with exemplary embodiments, it will be appreciated that variations and modifications will occur to those skilled in the art. For example, although the illustrative embodiments are described herein as a series of acts or events, it will be appreciated that the present invention is not limited by the illustrated ordering of such acts or events unless specifically stated. Some acts may occur in different orders and/or concurrently with other acts or events apart from those illustrated and/or described herein, in accordance with the invention. In addition, not all illustrated steps may be required to implement a methodology in accordance with the present invention. Furthermore, the methods according to the present invention may be implemented in association with the formation and/or processing of structures illustrated and described herein as well as in association with other structures not illustrated. Therefore, it is to be understood that the appended claims are intended to cover all such modifications and changes that fall within the true spirit of the invention.
Claims
1. A method of forming a semiconductor structure, the method comprising:
- forming a plurality of sacrificial Mx+1 lines over a plurality of metal Mx lines;
- depositing a dielectric layer over the plurality of sacrificial Mx+1 lines;
- forming a cut cavity in one sacrificial Mx+1 line of the plurality of sacrificial Mx+1 lines;
- forming a dielectric region in the cut cavity;
- removing the plurality of sacrificial Mx+1 lines to form a plurality of Mx+1 line cavities; and
- filling the plurality of Mx+1 line cavities with a metal to form a plurality of metal Mx+1 lines.
2. The method of claim 1, wherein forming a plurality of sacrificial Mx+1 lines comprises:
- depositing a sacrificial layer over the plurality of metal Mx lines;
- depositing a lithography stack on the sacrificial layer;
- patterning the lithography stack to form a patterned lithography stack;
- removing a portion of the sacrificial layer that is not covered by the patterned lithography stack; and
- removing the lithography stack.
3. The method of claim 1, wherein depositing a dielectric layer comprises depositing SiOC.
4. The method of claim 3, further comprising planarizing the dielectric layer.
5. The method of claim 4, wherein planarizing the dielectric layer comprises performing a chemical mechanical polish process.
6. The method of claim 1, wherein filling the plurality of Mx+1 line cavities with metal comprises filling the plurality of Mx+1 line cavities with copper.
7. A method of forming a semiconductor structure, the method comprising:
- forming a plurality of sacrificial Mx+1 lines over a plurality of metal Mx lines;
- depositing a dielectric layer over the plurality of sacrificial Mx+1 lines;
- depositing an organic planarization layer on the dielectric layer;
- depositing a resist layer on the organic planarization layer;
- forming a cavity in the resist layer and organic planarization layer;
- removing the resist layer;
- depositing a conformal spacer layer on the organic planarization layer;
- performing an anisotropic etch on the conformal spacer layer to form an aperture spacer;
- forming a cut cavity in one sacrificial Mx+1 line of the plurality of sacrificial Mx+1 lines;
- forming a dielectric region in the cut cavity;
- removing the plurality of sacrificial Mx+1 lines to form a plurality of Mx+1 line cavities; and
- filling the plurality of Mx+1 line cavities with a metal to form a plurality of metal Mx+1 lines.
8. The method of claim 7, wherein depositing a conformal spacer layer comprises depositing carbon.
9. The method of claim 8, wherein depositing carbon is performed with an atomic layer deposition process.
10. The method of claim 7, wherein forming a plurality of sacrificial Mx+1 lines comprises:
- depositing a sacrificial layer over the plurality of metal Mx lines;
- depositing a lithography stack on the sacrificial layer;
- patterning the lithography stack to form a patterned lithography stack;
- removing a portion of the sacrificial layer that is not covered by the patterned lithography stack; and
- removing the lithography stack.
11. The method of claim 7, wherein depositing a dielectric layer comprises depositing SiOC.
12. The method of claim 11, further comprising planarizing the dielectric layer.
13. The method of claim 12, wherein planarizing the dielectric layer comprises performing a chemical mechanical polish process.
14. The method of claim 7, wherein filling the plurality of Mx+1 line cavities with metal comprises filling the plurality of Mx+1 line cavities with copper.
15. A method of forming a semiconductor structure, the method comprising:
- forming a plurality of sacrificial Mx+1 lines over a plurality of metal Mx lines;
- depositing a dielectric layer over the plurality of sacrificial Mx+1 lines;
- forming a cut cavity in one sacrificial Mx+1 line of the plurality of sacrificial Mx+1 lines;
- forming a dielectric region in the cut cavity;
- removing the plurality of sacrificial Mx+1 lines to form a plurality of Mx+1 line cavities;
- depositing a via cut lithography stack;
- patterning an opening in the via cut lithography stack;
- forming a via cavity that exposes one Mx metal line of the plurality of metal Mx lines;
- removing the via cut lithography stack; and
- filling the plurality of Mx+1 line cavities and via cavity with a metal to form a plurality of metal Mx+1 lines and a via.
16. The method of claim 15, wherein forming a plurality of sacrificial Mx+1 lines comprises:
- depositing a sacrificial layer over the plurality of metal Mx lines;
- depositing a line cut lithography stack on the sacrificial layer;
- patterning the line cut lithography stack to form a patterned line cut lithography stack;
- removing a portion of the sacrificial layer that is not covered by the patterned line cut lithography stack; and
- removing the patterned line cut lithography stack.
17. The method of claim 15, wherein depositing a dielectric layer comprises depositing SiOC.
18. The method of claim 17, further comprising planarizing the dielectric layer.
19. The method of claim 18, wherein planarizing the dielectric layer comprises performing a chemical mechanical polish process.
20. The method of claim 19, wherein filling the plurality of Mx+1 line cavities with metal comprises filling the plurality of Mx+1 line cavities with copper.
Type: Application
Filed: Aug 20, 2014
Publication Date: Feb 25, 2016
Inventors: Andy Chih-Hung Wei (Queensbury, NY), Guillaume Bouche (Albany, NY), Mark A. Zaleski (Galway, NY)
Application Number: 14/463,801