# Patent

## Title
Patterning approach for improved via landing profile

## Abstract

The present disclosure is directed to a semiconductor structure and a method of manufacturing a semiconductor structure in which a spacer element is formed adjacent to a metal body embedded in a first dielectric layer of a first interconnect layer. A via which is misaligned relative to an edge of the metal body is formed in a second dielectric material in second interconnect layer disposed over the first interconnect layer and filled with a conductive material which is electrically coupled to the metal body. The method allows for formation of an interconnect structure without encountering the various problems presented by via substructure defects in the dielectric material of the first interconnect layer, as well as eliminating conventional gap-fill metallization issues.

## Background
CROSS REFERENCE TO RELATED APPLICATION
This application is a Divisional Patent Application claiming priority to U.S. patent application Ser. No. 13/794,999 with a filing date of Mar. 12, 2013, entitled “Novel Patterning Approach for Improved Via Landing Profile” in the name of Chih-Yuan Ting and is hereby incorporated in its entirety.


BACKGROUND
In semiconductor devices, it is known to etch through a dielectric material to make electrical contact to a conductive or semiconductor feature which is covered by the dielectric material. Electrical contact may be made by way of a via, for example, or by formation of a conductor formed by a damascene method.



BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a partial cross section view illustrating a semiconductor structure formed in accordance with a conventional process.
FIGS. 2A-2J are partial cross sectional views illustrating steps of one embodiment of forming a semiconductor device in accordance with the disclosure.
FIG. 3 illustrates a flow diagram of some embodiments of a method for the fabrication of a semiconductor device in accordance with the disclosure.



DETAILED DESCRIPTION
The description herein is made with reference to the drawings, wherein like reference numerals are generally utilized to refer to like elements throughout, and wherein the various structures are not necessarily drawn to scale. In the following description, for purposes of explanation, numerous specific details are set forth in order to facilitate understanding. It may be evident, however, to one of ordinary skill in the art, that one or more aspects described herein may be practiced with a lesser degree of these specific details. In other instances, known structures and devices are shown in block diagram form to facilitate understanding.
Semiconductor devices are manufactured or fabricated on semiconductor wafers using a number of different processing steps to create transistor and interconnection elements. To electrically connect transistor terminals associated with the semiconductor wafer, conductive (e.g., metal) trenches, vias, and the like are formed in dielectric materials as part of the semiconductor device. The trenches and vias couple electrical signals and power between transistors, internal circuits of the semiconductor devices, and circuits external to the semiconductor device.
In forming the interconnection elements the semiconductor wafer may undergo, for example, masking, etching, and deposition processes to form the desired electronic circuitry of the semiconductor devices. In particular, multiple masking and etching steps can be performed to form a pattern of recessed areas in a dielectric layer, such as a low-k dielectric layer, on a semiconductor wafer that serves as trenches and vias for the interconnections. A deposition process may then be performed to deposit a metal layer over the semiconductor wafer thereby depositing metal both in the trenches and vias and also on the non-recessed areas of the semiconductor wafer. To isolate the interconnections, such as patterned trenches and vias, the metal deposited on the non-recessed areas of the semiconductor wafer is removed.
The ongoing reduction of the feature sizes and of the integrated circuits gives rise to the general problem that subsequent metallization levels have to be aligned ever more precisely with respect to one another. However, a certain intrinsic misalignment is inevitable when one level is being lithographically mapped onto another. Therefore, the design has to incorporate certain tolerances which ensure that the contacts of one via level can land reliably on the respective interconnects of the metallization level below it.
A semiconductor substrate having a via on a metallization structure is shown, for example, in FIG. 1. In FIG. 1, a substrate 102 having a first etch stop layer 104 is provided. Overlying etch stop layer 104 is a first interconnect layer 101 including a metal body 118, for example, a copper metal body, embedded in a first dielectric layer 106. Encompassing bottom surface and sidewalls of metal body 118 is a barrier layer 116. The first interconnect layer 101 is separated from a second interconnect layer 101′ by a second etch stop layer 104′. The second interconnect layer 101′ includes a second dielectric material 106′ having a via opening 140 filled with a conductive material 134. A second barrier layer 132 separates the conductive material 134 from the second dielectric material 106′.
As critical dimensions of semiconductor integrated circuit devices shrink, the misalignment between the via opening 140 and the copper metal body 118 becomes more pronounced. When misalignment occurs, the dielectric layer 106 that encapsulates the landing metal body 118 is etched, resulting in a via substructure defect 150 next to the metal body 118. Such a defect results in a degradation of the overall wiring reliability as well as the strength of the via to wire connection.
In view of the problems associated with current methods for interconnect structures, there is a continued need for developing a new and improved integration scheme that improves the reliability and strength of the via-to-wire connection, without introducing damaged regions into the dielectric material.
Accordingly, the present disclosure is directed to a semiconductor structure and methods of fabrication of a semiconductor structure. The methods provide a process for defining an interconnect structure that eliminates conventional gap-fill metallization issues, as well as providing a better via landing profile when a via is not perfectly aligned with the metal body to which it is electrically coupled.
FIGS. 2A-2J illustrate a plurality of partial cross section diagrams illustrating one embodiment of a method of forming a semiconductor structure at stages in the manufacturing process according to the disclosure. Referring to FIG. 2A, there is provided a first interconnect layer 201 on a semiconductor substrate 202 in which an opening 214 has been formed. Substrate 202 is understood to include a semiconductor wafer or substrate, comprised of a semiconducting material such as silicon or germanium, or a silicon on insulator structure (SOI). Semiconductor structure can further include one or more conductive layers (such as metal or silicon) and/or insulating layers, and one or more active or passive devices formed in or over the substrate, or the like, for example, a display substrate such as a liquid crystal display (LCD), plasma display, electro-luminescence (EL) lamp display, or a light emitting diode (LED) substrate.
First interconnect layer 201 includes a first etch stop layer 204. Etch stop layer 204 comprises, in one embodiment, dielectric etch stop materials, for example, SiO2, SiN, SiC, SiCN. In another embodiment, the etch stop material may include AlN. The etch stop layer may be deposited employing methods including but to limited to chemical vapor deposition (CVD) methods, plasma enhanced chemical vapor deposition (PECVD) methods and physical vapor deposition (PVD) sputtering methods. In one embodiment, etch stop layer 204 thickness will be in a range of from about 10 angstroms to about 500 angstroms.
First interconnect layer 201 further includes a first dielectric layer 206 overlying first etch stop layer 204. The first dielectric layer 206 comprises, in one embodiment, a low k dielectric material having a dielectric constant of less than 3.0. The low-k dielectric includes dielectrics with k less than about 3. Such dielectrics include, for example, carbon-doped silicon dioxide, also referred to as organosilicate glass (OSG) and carbon-oxide. Low-k materials may also include borophosphosilicate glass (BPSG), borosilicate glass (BSG), and phosphosilicate glass (PSG), among others. The dielectric layer 206 may be formed using, for example, tetraethyl orthosilicate (TEOS), chemical vapor deposition (CVD), plasma enhanced CVD (PECVD), low pressure CVD (LPCVD), or spin-on coating techniques. First dielectric layer may comprise a material such as SiCOH or SiO2. The first dielectric layer 206 will have a thickness of from about 600 angstroms to about 3000 angstroms.
A capping layer 208 is formed overlying first dielectric layer 206. Capping layer 208 comprises combinations of carbon, silicon, nitrogen, and oxygen, such as silicon oxycarbide, silicon nitride, silicon oxynitride, and the like. The method of formation includes commonly used methods such as chemical vapor deposition (CVD), physical vapor deposition (PVD), spin-on (for spin-on glass), atomic layer deposition (ALD), and the like. The thickness of the capping layer is between about 50 angstroms and about 500 angstroms.
A hard mask layer 210 overlies capping layer 208. The hard mask layer 208 is used in a subsequent photolithographic process to form opening 214 in first dielectric layer 206. In some embodiments, the hard mask layer 210 comprises a material such as titanium nitride. The hard mask layer 210 will have a thickness of from about 100 angstroms to about 500 angstroms in one embodiment.
In FIG. 2B, a metal is deposited (not shown) to fill opening 214 in first dielectric layer 206 to form a metal body 218 embedded within dielectric layer 206. Metal body 218 is defined by a bottom surface 221 and opposing sidewalls 222(a), 222(b) having first and second edges 223(a), 223(b). In one embodiment, the metal body 218 can be formed from elements such as Al, W, Cu, Cu alloys, and the like. Metal body 218 can be formed using, for example, a plasma vapor deposition technique, among others. Metal body 218 can have a height, in one embodiment, of from about 300 angstroms to about 1500 angstroms.
Prior to filling of opening 214 with metal body 218, a first barrier layer 216 can be deposited to line opening 214 and encompass bottom surface 221 and opposing sidewalls 222(a), 222(b) of metal body 218. First barrier layer 216 may comprise, in one embodiment, a material such as Ta, TaN, Co, W, TiSiN, TaSiN, or combinations thereof. The first barrier layer 216 may be formed at a thickness of from about 15 Å to about 1500 Å. A chemical mechanical polishing (CMP) process (not shown) can then be performed to remove excess metal and expose an upper surface 219u of metal body 218, as illustrated in FIG. 2B.
Following the CMP process, a second hard mask layer 208′ is deposited overlying metal body 218 and first dielectric layer 206, as illustrated in FIG. 2C. Hard mask layer 208′ is photolithographically patterned to provide an opening 224 therein, as illustrated in FIG. 2D. The opening 224 is positioned so as to be disposed over first edge 223(a) of metal body 218. An etch process (not shown) is then performed to etch through first dielectric layer 206 and a sidewall 222(a) of metal body 218, forming a second opening 226 therein, as illustrated in FIG. 2E. Second opening 226 is adjacent to metal body 218 and includes a sidewall 219s contiguous with the metal body 218
A spacer element 228 is then formed in FIG. 2G by deposition of a spacer material overlying hard mask layer 208′ and filling second opening 226. Spacer material may comprise, in one embodiment, dielectric materials, for example, SiO2, SiN, SiC, SiCN. In another embodiment, the spacer material may include AlN. In one embodiment, the spacer element 228 may be formed from the same material as the etch stop layer 204. In another embodiment, the spacer element 228 and the etch stop layer 204 may be formed from different materials. The spacer element 228 may be deposited, in one embodiment, by a method such as atomic layer deposition. Spacer element 228 may have a height, in one embodiment, of greater than or equal to 1500 A°. In one embodiment, the height of the spacer element will be greater than or equal to the height of the metal body 218. Following formation of spacer element 228, hard mask layer 208′ and spacer material overlying hard mask layer 208′ are removed, as by a CMP process (not shown) such that spacer element 228, metal body 218 and first barrier layer 216 each have an upper surface that is substantially coplanar, as illustrated in FIG. 2G.
After formation of the first interconnect layer 201, a second etch step layer 204′ is deposited overlying the first interconnect layer 201, as shown in FIG. 2H. Second etch stop layer 204′ may comprise the same material as first etch stop layer 204. A second interconnect layer 201′ may then be formed overlying first interconnect structure 201 by depositing a second dielectric material 206′ over second etch stop layer 204′. The second dielectric material 206′ may comprise the same or different materials as that of the first dielectric material 206. The processing techniques and thickness ranges for the first dielectric material 206 are applicable for the second dielectric material 206′.
A dielectric capping layer 260 is formed overlying the second interconnect layer 201′, as shown in FIG. 2H. Dielectric capping layer 260 may be formed utilizing a conventional process, such as, for example, chemical vapor deposition (CVD), PECVD, and the like. The capping layer 260 may comprise any suitable dielectric capping material, such as SiC, SiO2, SiN or SiCN. The capping layer 260 may be formed at a thickness of from about 50 angstroms to about 500 angstroms.
At least one opening such as a dual damascene trench and via structure 232 is formed in the second dielectric layer 206′ utilizing conventional photolithographic techniques, as previously described. In one embodiment, the etching may comprise a dry etch such as reactive ion etching, ion beam etching, plasma etching, and the like. As illustrated in FIG. 2I, the etching process provides at least one dual damascene trench and via structure 232 in the second dielectric layer 206′. The at least one dual damascene trench and via structure 232 may comprise a via which is misaligned relative to an edge 223(a) of the metal body 218 and extends into a top surface of the spacer element 228 and the metal body 218 to form a via substructure defect 250. A portion of the misaligned via lands on the metal body 218, while other portions of the misaligned via are formed in the adjacent spacer element 228. As is illustrated, then, in comparison with FIG. 1, the semiconductor structure of FIG. 2I has a significantly reduced via substructure defect 250 in the dielectric material 206′ of the first interconnect layer 201, while eliminating conventional gap-fill metallization issues.
In FIG. 2J, a second barrier layer 242 is disposed between second dielectric material 206′ and conductive material 240. Second barrier layer 242 may comprise the same material as first barrier layer 216, or a different material. The conductive material 240 is then deposited to fill the dual damascene trench and via structure 232 and electrically couple the conductive material 240 to the metal body 218 of the first interconnect layer 201. A CMP process may then be performed to planarize conductive material 240.
FIG. 3 illustrates a flow diagram of some embodiments of a method 300 for formation of a semiconductor structure according to an embodiment of the disclosure. While method 300 is illustrated and described below as a series of acts or events, it will be appreciated that the illustrated ordering of such acts or events are not to be interpreted in a limiting sense. For example, some acts may occur in different orders and/or concurrently with other acts or events apart from those illustrated and/or described herein. In addition, not all illustrated acts may be required to implement one or more aspects or embodiments of the description herein. Further, one or more of the acts depicted herein may be carried out in one or more separate acts and/or phases.
At 302 a first interconnect layer is provided. The first interconnect layer includes a dielectric material with a metal body, for example, a copper metal body, embedded therein. An opening is then formed in the first dielectric layer at 304.
At 306, a spacer element is formed in the opening. The spacer element has a sidewall contiguous with a sidewall of the metal body.
At 308, a second interconnect layer is provided overlying the first interconnect layer. Second interconnect layer includes a second dielectric material.
At 310, an opening is formed in the second dielectric layer by etching.
At 312, the opening is filled with a conductive material to electrically couple the conductive material to the metal body of the first interconnect layer. The method then ends.
It will be appreciated that equivalent alterations and/or modifications may occur to one of ordinary skill in the art based upon a reading and/or understanding of the specification and annexed drawings. The disclosure herein includes all such modifications and alterations and is generally not intended to be limited thereby. In addition, while a particular feature or aspect may have been disclosed with respect to only one of several implementations, such feature or aspect may be combined with one or more other features and/or aspects of other implementations as may be desired. Furthermore, to the extent that the terms “includes”, “having”, “has”, “with”, and/or variants thereof are used herein, such terms are intended to be inclusive in meaning—like “comprising.” Also, “exemplary” is merely meant to mean an example, rather than the best. It is also to be appreciated that features, layers and/or elements depicted herein are illustrated with particular dimensions and/or orientations relative to one another for purposes of simplicity and ease of understanding, and that the actual dimensions and/or orientations may differ substantially from that illustrated herein.
Therefore, the disclosure relates to a semiconductor structure comprising a first interconnect layer including a first dielectric layer having a metal body therein. The metal body is defined by opposing sidewalls having first and second edges and a bottom surface. The semiconductor structure further includes a spacer element adjacent to the metal body, the spacer element having a sidewall contiguous with a sidewall of the metal body. The semiconductor structure further includes a second interconnect layer overlying the first interconnect layer and including a second dielectric material having at least one opening therein. The opening is filled with a conductive material which is electrically coupled to the metal body of the first interconnect layer.
The disclosure further relates to a method of forming a semiconductor structure comprising providing a first interconnect layer by forming a first dielectric layer having a metal body embedded therein, the metal body comprising a bottom surface and opposing sidewalls having first and second edges. The method further comprises forming a second opening in the first dielectric layer, the second opening adjacent to the metal body and having a sidewall contiguous with the metal body. The method further comprises forming a spacer element in the second opening. The method further comprises providing a second interconnect layer by forming a second dielectric layer and forming at least one dual damascene trench and via structure in the second dielectric layer, the via connecting to the metal body in the first interconnect layer, and filling the structure with a conductive material, the conductive material electrically coupled with the metal body of the first interconnect layer.
The disclosure further relates to a semiconductor structure that comprises a first dielectric layer overlying a semiconductor body, and a metal body residing in the first dielectric layer, the metal body having a first sidewall defining a first edge, and a second, opposing sidewall defining a second edge. The semiconductor structure further comprises a spacer element formed contiguous to the first edge of the metal body, which forms an interface thereat, and a second dielectric layer overlies the first dielectric layer and has a conductive damascene structure therein having a bottom surface that straddles the interface, wherein the conductive damascene structure makes conductive contact with the metal body.

## Claims

1. A method of forming a semiconductor structure, comprising:
providing a semiconductor substrate;
forming a first dielectric layer over the semiconductor substrate, wherein the first dielectric layer includes an opening therein;
forming a metal body in the opening;
removing a first portion of the metal body to leave a sidewall of the metal body exposed;
forming a spacer element along the exposed sidewall of the metal body, wherein a sidewall of the spacer element and the sidewall of the metal body meet at an interface;
forming a second dielectric layer over the first dielectric layer, over the metal body, and over the spacer element; and
forming a conductive via which extends downwardly through the second dielectric layer, the conductive via being directly over the interface and being electrically coupled to the metal body.

2. The method of claim 1, wherein the spacer element has a lowermost surface that extends downward past a lowermost surface of the metal body without extending upwards along a second sidewall of the metal body, which is opposite the sidewall.

3. The method of claim 1, wherein forming the spacer element comprises:
forming a first mask over the first dielectric layer and over the metal body, wherein the first mask covers a second portion of the metal body and has a mask opening that leaves exposed both the first portion of the metal body and a region of the first dielectric layer adjacent to the first portion of the metal body;
performing an etch to remove both the first portion of the metal body and the region of the first dielectric layer while leaving the second portion of the metal body in place, thereby leaving a spacer opening alongside the second portion of the metal body; and
forming the spacer element in the spacer opening.

4. The method of claim 1, further comprising:
prior to forming the metal body, forming a barrier layer on a sidewall and lower surface of the opening, and subsequently forming the metal body over the barrier layer to fill the opening.

5. The method of claim 4, wherein forming the spacer element comprises:
forming a first mask over the metal body, over the barrier layer, and over the first dielectric layer, wherein the first mask covers a second portion of the metal body, a first portion of the barrier layer, and a first portion of the first dielectric layer, and wherein the first mask has a mask opening that exposes the first portion of the metal body, a second portion of the barrier layer, and a second portion of the first dielectric layer;
performing a first etch to remove the first portion of the metal body, the second portion of the barrier layer, and the second portion of the first dielectric layer, thereby leaving a spacer opening alongside the second portion of the metal body; and
forming the spacer element in the spacer opening.

6. The method of claim 1, wherein the metal body comprises copper, copper alloy, tungsten, or aluminum.

7. The method of claim 1, wherein the spacer element comprises silicon dioxide, silicon nitride, silicon carbide, silicon nitride carbide, or aluminum nitride.

8. A method of forming a semiconductor structure, comprising:
providing a semiconductor substrate with a first dielectric layer over the semiconductor substrate;
forming a first opening in the first dielectric layer;
forming a metal body that fills the first opening;
forming a first mask over the first dielectric layer and over the metal body, wherein the first mask covers a first portion of the metal body and covers a first portion of the first dielectric layer and has a mask opening that leaves exposed both a second portion of the metal body and a second portion of the first dielectric layer adjacent to the second portion of the metal body;
performing a first etch to remove both the second portion of the metal body and the second portion of the first dielectric layer while leaving the first portion of the metal body in place, thereby leaving a spacer opening alongside the first portion of the metal body; and
forming a spacer element in the spacer opening.

9. The method of claim 8, further comprising:
planarizing an upper surface of the metal body and an upper surface of the spacer element so the planarized upper surface of the metal body is co-planar with the planarized upper surface of the spacer element.

10. The method of claim 8, further comprising:
forming a second dielectric layer over the first dielectric layer, over the metal body, and over the spacer element;
forming a second opening in the second dielectric layer, wherein the second opening exposes an upper surface of the spacer element and an upper surface of the first portion of the metal body; and
forming a conductive via which extends through the second dielectric layer and which is electrically coupled to the metal body.

11. The method of claim 10, wherein a sidewall of the first portion of the metal body is in direct lateral contact with a sidewall of the spacer element at an interface, and wherein the conductive via has a lowermost surface directly over the interface.

12. The method of claim 11, wherein the lowermost surface of the conductive via extends below an uppermost surface of the metal body and extends beneath an uppermost surface of the spacer element.

13. The method of claim 8, further comprising:
prior to forming the metal body, forming a barrier layer on a sidewall and lower surface of the opening, and subsequently forming the metal body over the barrier layer to fill the opening.

14. The method of claim 13:
wherein the first mask covers a first portion of the metal body, a first portion of the barrier layer, and a first portion of the first dielectric layer, and wherein the first mask has a mask opening that exposes a second portion of the metal body, a second portion of the first dielectric layer, and a second portion of the barrier layer;
wherein the first etch removes the second portion of the metal body, the second portion of the first dielectric layer, and the second portion of the barrier layer, thereby leaving the spacer opening alongside the first portion of the metal body.

15. A method of forming a semiconductor structure, comprising:
providing a semiconductor substrate;
providing a first interconnect layer over the semiconductor substrate by forming a first dielectric layer and forming a first opening in the first dielectric layer, the first opening having a metal body embedded therein, the metal body comprising a bottom surface, a first sidewall and a second, opposing sidewall, wherein the first and second sidewalls define a first edge and a second edge, respectively;
forming a second opening in the first dielectric layer, the second opening adjacent to the metal body and having a sidewall contiguous with the first sidewall of the metal body;
forming a spacer element filling the second opening; and
providing a second interconnect layer by forming a second dielectric layer and forming at least one via opening in the second dielectric layer, the at least one via opening extending to the metal body, and filling the at least one via opening with a conductive material, the conductive material electrically coupled to the metal body of the first interconnect layer.

16. The method of claim 15, wherein forming the at least one via opening in the second dielectric layer comprises forming a via opening which is misaligned relative to the metal body such that the via opening overlies the first edge of the metal body by etching through the second dielectric layer and into a top surface of the spacer element.

17. The method of claim 15, wherein forming the spacer element comprises depositing the layer by atomic layer deposition (ALD).

18. The method of claim 17, wherein a height of the spacer element is greater than or substantially equal to a height of the metal body.

19. The method of claim 15, further comprising forming a first barrier between the metal body and the first dielectric layer and forming a second barrier layer between the conductive material and the second dielectric layer.

20. The method of claim 15, further comprising forming a first etch stop layer (ESL) between the semiconductor substrate and the first dielectric layer and forming a second ESL between the first interconnect layer and the second interconnect layer.