Semiconductor device including contact plug and associated methods

A semiconductor device and associated methods, the semiconductor device including a semiconductor layer including a first region and a second region, a first contact plug disposed on the semiconductor layer and electrically connected to the first region, a second contact plug disposed on the semiconductor layer and electrically connected to the second region, a conductive layer electrically connected to the first contact plug, the conductive layer having a side surface and a bottom surface, and an insulating layer disposed between the conductive layer and the second contact plug so as to insulate the conductive layer from the second contact plug, the insulating layer facing the side surface and a portion of the bottom surface of the conductive layer.

BACKGROUND

Embodiments relate to a semiconductor device including a contact plug and associated methods.

2. Description of the Related Art

An active region of a substrate in a semiconductor device may be electrically connected to another structure via a contact plug. Due to the small size of such semiconductor devices, research has been conducted into the formation of a reliable contact plug in a minute region. In this regard, the research has been conducted into a method of forming a self aligning contact (SAC) by which a bit line contact plug and a bit line may first be formed, and then a storage contact plug may be formed using a spacer, which may cover the bit line, as a mask.

SUMMARY

Embodiments are directed to a semiconductor device including a contact plug and associated methods, which substantially overcome one or more of the drawbacks, limitations, and/or disadvantages of the related art.

It is a feature of an embodiment to provide a semiconductor device including a contact plug capable of providing an excellent electrical contact with an active region of a substrate.

At least one of the above and other features and advantages may be realized by providing a semiconductor device including a semiconductor layer including a first region and a second region, a first contact plug disposed on the semiconductor layer and electrically connected to the first region, a second contact plug disposed on the semiconductor layer and electrically connected to the second region, a conductive layer electrically connected to the first contact plug, the conductive layer having a side surface and a bottom surface, and an insulating layer disposed between the conductive layer and the second contact plug so as to insulate the conductive layer from the second contact plug, the insulating layer facing the side surface and a portion of the bottom surface of the conductive layer.

The second contact plug may include a lower portion and an upper portion, and a cross-sectional area of the lower portion of the second contact plug may be greater than a cross-sectional area of the upper portion of the second contact plug.

The insulating layer may include a bottom surface and at least a portion of the second contact plug may face the bottom surface of the sidewall insulating layer.

The insulating layer may include a first side surface and a second side surface, the first side surface facing the second contact plug and having a first height, the second side surface facing away from the second contact plug and having a second height.

The first height may be greater than the second height.

The first contact plug may include a material different from a material in the second contact plug.

The first contact plug may include a material the same as a material in the second contact plug.

The semiconductor device may further include an etch stopping layer interposed between the first contact plug and the first conductive layer.

The conductive layer may be a bit line, the first contact plug may be a bit line contact plug connected to the bit line, and the second contact plug may be a storage contact plug.

At least one of the above and other features and advantages may also be realized by providing a semiconductor device including a semiconductor layer including a plurality of active regions, a bit line contact plug disposed on the semiconductor layer and electrically connected to one of the plurality of active regions, a storage contact plug disposed on the semiconductor layer and electrically connected to another one of the plurality of active regions, a bit line electrically connected to the bit line contact plug, the bit line having a side surface and a bottom surface, a storage capacitor electrically connected to the storage contact plug, and an insulating layer disposed between the bit line and the storage contact plug so as to insulate the bit line from the storage contact plug, the insulating layer having a bottom surface, the insulating layer facing the side surface and a portion of the bottom surface of the bit line, at least a portion of the bottom surface of the insulating layer facing the storage contact plug.

At least one of the above and other features and advantages may also be realized by providing a method of manufacturing a semiconductor device including forming a first interlayer insulating layer on a semiconductor layer, forming a first contact plug in the first interlayer insulating layer, covering the first interlayer insulating layer with a second interlayer insulating layer, forming a second contact plug in the second interlayer insulating layer and the first interlayer insulating layer, forming a third interlayer insulating layer on the second interlayer insulating layer, patterning the third interlayer insulating layer, patterning a portion of the second interlayer insulating layer by using the patterned third interlayer insulating layer as an etch mask to form one opening, the one opening exposing at least a portion of the second contact plug, forming another opening by etching the portion of the second contact plug exposed by the one opening, forming a sidewall insulating layer in the one opening and the other opening, and forming a conductive layer in the one opening.

The forming the conductive layer in the one opening may include filling at least a portion of the one opening with a conductive material.

The method may further include forming a fourth interlayer insulating layer on the conductive layer.

The first contact plug, the second contact plug, and the conductive layer may each be independently formed to include at least one of polysilicon, aluminum (Al), gold (Au), beryllium (Be), bismuth (Bi), cobalt (Co), copper (Cu), hafnium (Hf), indium (In), manganese (Mn), molybdenum (Mo), nickel (Ni), lead (Pb), palladium (Pd), platinum (Pt), rhodium (Rh), rhenium (Re), ruthenium (Ru), tantalum (Ta), tellurium (Te), titanium (Ti), tungsten (W), zinc (Zn), and zirconium (Zr).

The method may further include forming an etch stopping layer on the first interlayer insulating layer prior to covering the first interlayer insulating layer with the second interlayer insulating layer.

The forming the sidewall insulating layer may include fashioning the sidewall insulating layer to have a bottom surface, at least a portion of the bottom surface of the sidewall insulating layer facing the second contact plug.

DETAILED DESCRIPTION

Korean Patent Application No. 10-2009-0012599, filed on Feb. 16, 2009, in the Korean Intellectual Property Office, and entitled: “Semiconductor Device Including Contact Plug,” is incorporated by reference herein in its entirety.

It will be understood that when an element, such as a layer, a region, or a substrate, is referred to as being “connected to” or “coupled to” another element, it may be directly connected or coupled to the other element or intervening elements may be present. When an element is referred to as being “directly on,” “directly connected to” or “directly coupled to” another element or layer, there are no intervening elements or layers present. As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items.

Exemplary embodiments are described herein with reference to illustrations that are schematic illustrations of exemplary embodiments (and intermediate structures). As such, variations from the shapes of the illustrations as a result, for example, of manufacturing techniques and/or tolerances, are to be expected. Thus, exemplary embodiments should not be construed as limited to the particular shapes of regions illustrated herein but may be to include deviations in shapes that result, for example, from manufacturing. For example, an implanted region illustrated as a rectangle may, typically, have rounded or curved features and/or a gradient of implant concentration at its edges rather than a binary change from implanted to non-implanted region. Likewise, a buried region formed by implantation may result in some implantation in the region between the buried region and the surface through which the implantation takes place. Thus, the regions illustrated in the figures are schematic in nature and their shapes may be not intended to illustrate the actual shape of a region of a device and are not intended to limit the scope of exemplary embodiments.

FIG. 1illustrates a cross-sectional view of a semiconductor device1including contact plugs according to an embodiment. Referring toFIG. 1, a first interlayer insulating layer110, an etch stopping layer130, and a second interlayer insulating layer140may be sequentially disposed on a semiconductor layer100including a first region and a second region.

The semiconductor layer100may include a substrate including a semiconductor material, e.g., silicon and silicon-germanium, an epitaxial layer, a silicon-on-insulator (SOI) layer, and/or a semiconductor-on-insulator (SEOI) layer. The semiconductor layer100may include, e.g., a device isolation layer (not shown), an active region (not shown), and a gate structure (not shown). The active region (not shown) may include, e.g., a source/drain region (not shown) and/or a channel region (not shown). The gate structure (not shown) may be a general transistor and may include, e.g., a gate insulating layer, a gate electrode, a spacer, and a capping layer.

The first region will now be described. A first contact plug120may be disposed on the semiconductor layer100, penetrating the first interlayer insulating layer110. The first contact plug may be electrically connected to the first region of the semiconductor layer100. A conductive layer180may be disposed on the first contact plug120. A fourth interlayer insulating layer190may be disposed on the conductive layer180. Although the etch stopping layer130is illustrated inFIG. 1as being interposed between the first and second insulating layers110and140, the etch stopping layer130may also be disposed between the conductive layer180and the first contact plug120. A sidewall insulating layer170may be disposed between the second interlayer insulating layer140and the conductive layer180, and between the second interlayer insulating layer140and the fourth interlayer insulating layer190.

The conductive layer180may be a bit line and the first contact plug120may be a bit line contact plug connected to the bit line. Also, the first region may be the active region, that is, the source/drain region, and thus, the first contact plug120may be electrically connected to the source/drain region. However, the embodiments are not limited thereto.

The second region will now be described. The second contact plug150may be disposed on the semiconductor layer100, penetrating the first interlayer insulating layer110and the second interlayer insulating layer140. The second contact plug150may be electrically connected to the second region of the semiconductor layer100. The sidewall insulating layer170may be disposed between the second contact plug150and at least a portion of the first interlayer insulating layer110. In particular, the second contact plug150may extend under the sidewall insulating layer to face at least a portion of a bottom surface of the sidewall insulating layer170. Also, the sidewall insulating layer170may face a portion of a side surface of the second contact plug150that extends above the first interlayer insulating layer110. The conductive layer180may be disposed on the first interlayer insulating layer110. Portions of a side surface and a bottom surface of the conductive layer180may face the sidewall insulating layer170so that the conductive layer180may be insulated by, e.g., being separated, from the second contact plug150. Thus, the conductive layer180and the second contact plug150may be electrically insulated from one another due to the sidewall insulating layer170. Also, another portion of the sidewall insulating layer170may contact both the conductive layer180and the second interlayer insulating layer140.

The fourth interlayer insulating layer190may be disposed on the conductive layer180. The fourth interlayer insulating layer190may be surrounded by the sidewall insulating layer170. The sidewall insulating layer170may include a first side surface and a second side surface, wherein the first side surface faces the second contact plug150and has a first height, and the second side surface faces away from the second contact plug150, contacts the second interlayer insulating layer140, and has a second height. The first height may be greater than the second height. A storage capacitor195may be disposed on and electrically connected to the second contact plug150.

The second region may be the active region, that is, the source/drain region, and thus, the second contact plug150may be electrically connected to the source/drain region. The second contact plug150may be a storage contact plug connected to the storage capacitor195. However, the embodiments are not limited thereto.

The semiconductor device1according to the embodiment illustrated inFIG. 1may be, e.g., a Dynamic Random Access Memory (DRAM) device. However, the embodiments are not limited thereto and the semiconductor device according to an embodiment may also be, e.g., a Static Random Access Memory (SRAM) device or a non-volatile memory device.

FIGS. 2A through 12Aillustrate plan views of stages in a method of manufacturing the semiconductor device ofFIG. 1.FIGS. 2B through 12Billustrate cross-sectional views of stages in a method of manufacturing the semiconductor device ofFIG. 1, which are respectively taken along the lines A-A′ and B-B′ ofFIGS. 2A through 12A. In other words,FIGS. 2B,3B,4B,5B,6B,7B,8B,9B,10B,11B, and12B are cross-sectional views of the semiconductor device, taken along lines A-A′ and B-B′ ofFIGS. 2A,3A,4A,5A,6A,7A,8A,9A,10A,11A, and12A, respectively. The cross-sectional view taken along the line A-A′ corresponds to the first region and the cross-sectional view taken along the line B-B′ corresponds to the second region.

Referring toFIGS. 2A and 2B, a semiconductor layer100may be prepared. A buffer insulating layer (not shown) including, e.g., a silicon oxide, may be formed on the semiconductor layer100. A hard mask layer including, e.g., polysilicon or a silicon nitride, may be formed on the semiconductor layer100or the buffer insulating layer. Detailed descriptions of layers such as a sacrificial layer, a buffer layer, a pad layer, and a hard mask layer that are formed by deposition and removed by etching so as to form the semiconductor device are not provided here.

A first interlayer insulating layer110may be formed on the semiconductor layer100. The first interlayer insulating layer110may include, e.g., a silicon oxide, a silicon nitride, or a silicon oxynitride. The first interlayer insulating layer110may be formed by, e.g., thermal oxidation, rapid thermal oxidation (RTO), chemical vapor deposition (CVD), plasma enhanced CVD (PECVD), high density plasma CVD (HDP-CVD), sputtering, atomic layer deposition (ALD), or the like.

Then, a portion of the first interlayer insulating layer110may be patterned to form first openings112in the first interlayer insulating layer110, exposing the semiconductor layer100. This patterning may be performed by a typical method using, e.g., a photoresist or a hard mask. An etching method used to form the first openings112may be, e.g., an anisotropic etching method including reactive ion etching (RIB) and plasma etching, or a sloped etching method, but the embodiments are not limited thereto.

Referring toFIGS. 3A and 3B, the first openings112may be filled with a first conductive material, and thus, first contact plugs120(hereinafter, referred to as ‘the first contact plug120’) may be formed. The first conductive material may include, e.g., polysilicon, aluminum (Al), gold (Au), beryllium (Be), bismuth (Bi), cobalt (Co), copper (Cu), hafnium (Hf), indium (In), manganese (Mn), molybdenum (Mo), nickel (Ni), lead (Pb), palladium (Pd), platinum (Pt), rhodium (Rh), rhenium (Re), ruthenium (Ru), tantalum (Ta), tellurium (Te), titanium (Ti), tungsten (W), zinc (Zn), and/or zirconium (Zr). The first conductive material may further include, e.g., a nitride or a silicide. If polysilicon is used, it may be doped with n-type impurities or p-type impurities. The first contact plug120may further include a barrier layer (not shown) for, e.g., lowering a potential barrier between contacts. The barrier layer may be a monolayer including, e.g., titanium (Ti), tantalum (Ta), or tungsten (W), or may be a multilayer including, e.g., titanium/titanium nitride (Ti/TiN), tantalum/tantalum nitride (Ta/TaN), or tungsten/tungsten nitride (W/WN). However, materials and layers included in the first contact plug120are not limited to the aforementioned materials and layers.

A planarization process including, e.g., an etch-back and/or chemical mechanical polishing (CMP), may be performed, so that an uppermost surface of the first contact plug120is the same level as an uppermost surface of the first interlayer insulating layer110. The first contact plug120may be electrically connected to the active region of the semiconductor layer100. The active region may be the source/drain region. Also, the first contact plug120may be electrically connected to a gate electrode of a gate structure included in the semiconductor layer100.

Referring toFIGS. 4A and 4B, an etch stopping layer130and a second interlayer insulating layer140may cover the first interlayer insulating layer110and the first contact plug120. The etch stopping layer130may include, e.g., a silicon oxide, a silicon nitride, or a silicon oxynitride. In addition, the etch stopping layer130may include a material different from the first interlayer insulating layer110. The second interlayer insulating layer140may include, e.g., a silicon oxide, a silicon nitride, or a silicon oxynitride. The second interlayer insulating layer140may include a material different from the etch stopping layer130. The second interlayer insulating layer140may include the same material as the first interlayer insulating layer110. Referring toFIG. 4A, the first contact plug120is denoted using a dotted line, meaning that other layers, e.g., the etch stopping layer130and the second interlayer insulating layer140, are formed above the first contact plug120.

Referring toFIGS. 5A and 5B, portions of the second interlayer insulating layer140, the etch stopping layer130, and the first interlayer insulating layer110may be patterned to form second openings142exposing the semiconductor layer100through the second interlayer insulating layer140, the etch stopping layer130, and the first interlayer insulating layer110. This patterning operation may be performed according to a typical method using, e.g., a photoresist or a hard mask. The second openings142may not contact the first contact plug120. The embodiments are not limited to a specific alignment of the second openings142shown inFIG. 5A.

Referring toFIGS. 6A and 6B, the second openings142(hereinafter, referred to as “the second opening142”) may be filled with a second conductive material and thus, second contact plugs150(hereinafter, referred to as “the second contact plug150”) may be formed. The second conductive material may include, e.g., polysilicon, aluminum (Al), gold (Au), beryllium (Be), bismuth (Bi), cobalt (Co), copper (Cu), hafnium (Hf), indium (In), manganese (Mn), molybdenum (Mo), nickel (Ni), lead (Pb), palladium (Pd), platinum (Pt), rhodium (Rh), rhenium (Re), ruthenium (Ru), tantalum (Ta), tellurium (Te), titanium (Ti), tungsten (W), zinc (Zn), and/or zirconium (Zr). The second conductive material may further include, e.g., a nitride or silicide. If polysilicon is used, it may be doped with n-type impurities or p-type impurities. The second contact plug150may further include a barrier layer (not shown) for, e.g., lowering a potential barrier between contacts. The barrier layer may be a monolayer including, e.g., titanium (Ti), tantalum (Ta) or tungsten (W), or may be a multilayer including, e.g., titanium/titanium nitride (Ti/TiN), tantalum/tantalum nitride (Ta/TaN), or tungsten/tungsten nitride (W/WN). However, materials and layers included in the second contact plug150are not limited to the aforementioned materials and layers. The second conductive material of the second contact plug150may be to the same as or different from the first conductive material of the first contact plug120.

A planarization process including, e.g., etch-back and/or CMP, may be performed, so that an uppermost surface of the second contact plug150is the same level as an uppermost surface of the second interlayer insulating layer140. The second contact plug150may be electrically connected to the active region of the semiconductor layer100. The active region may be the source/drain region. Also, the second contact plug150may be electrically connected to a gate electrode of a gate structure included in the semiconductor layer100. Here, the active region to which the second contact plug150is electrically connected may be different from the active region to which the first contact plug120is electrically connected. That is, if the first contact plug120is electrically connected to the drain region of the source/drain region, the second contact plug150may be electrically connected to the source region of the source/drain region, or vice versa.

Referring toFIGS. 7A and 7B, a third interlayer insulating layer160may cover the second interlayer insulating layer140and the second contact plug150. The third interlayer insulating layer160may serve as a hard mask, and may include, e.g., a silicon oxide, a silicon nitride, or a silicon oxynitride. The third interlayer insulating layer160may include a different material from the second interlayer insulating layer140. Referring toFIG. 7A, the second contact plug150is also denoted using a dotted line, meaning that other layers including the third interlayer insulating layer160are formed above the second contact plug150.

Referring toFIGS. 8A and 8B, the third interlayer insulating layer160may be patterned. Then, a portion of the second interlayer insulating layer140may be patterned using the third interlayer insulating layer160as an etch mask so that third openings162(hereinafter, referred to in the singular as one opening, i.e., as “the third opening162”) may be formed to expose portions of the etch stopping layer130and the second contact plug150. In a region including the first contact plug120, the third opening162may expose a portion of the etch stopping layer130and the second interlayer insulating layer140at a side portion thereof. In a region including the second contact plug150, the third opening162may expose a portion of the etch stopping layer130at a lowermost portion thereof and the second interlayer insulating layer140at the side portion thereof. In addition, the third opening162may expose at least a portion of the second contact plug150.

Referring toFIGS. 9A and 9B, the portion of the etch stopping layer130exposed by the third opening162may be removed to expose the first contact plug120under the etch stopping layer130. In the case where the third interlayer insulating layer160includes the same material as the etch stopping layer130, the third interlayer insulating layer160may be removed, or its height may be lowered in a process related toFIGS. 9A and 9B. Furthermore, a portion of the second contact plug150exposed by the third opening162may be further etched downwardly (that is, an over-etching) so that fourth openings164(hereinafter, referred to in the singular as another opening, i.e., as “the fourth opening164”) may be formed. The fourth opening164may be formed by using, e.g., an anisotropic dry etching method. Removal of portions of the second contact plug150may be controlled to prevent the fourth opening164from exposing the semiconductor layer100.

Also, in the case where the first contact plug120and the second contact plug150include different materials, the first contact plug120may not be etched during the above-described over-etching process in which the fourth opening164is formed. For this, the first contact plug120may include a material having a high etching selectivity with respect to the material of second contact plug150. However, in the case where the first contact plug120and the second contact plug150include the same material, the first contact plug120would be etched during the above-described over-etching process in which the fourth opening164is formed. Accordingly, the etch stopping layer130may remain on the first contact plug120during over etching of the second contact plug150.

Referring toFIGS. 10A and 10B, the sidewall insulating layer170may be formed in the third opening162and the fourth opening164. The sidewall insulating layer170may include, e.g., a silicon oxide, a silicon nitride, or a silicon oxynitride. The sidewall insulating layer170may be formed by using, e.g., CVD, Physical Vapor Deposition (PVD), or ALD, but the embodiments are not limited thereto. Thus, the sidewall insulating layer170may be formed by using any suitable deposition method. The sidewall insulating layer170may cover side walls in the third opening162. That is, in the region including the first contact plug120, the sidewall insulating layer170may cover side walls of the etch stopping layer130, the second interlayer insulating layer140, and/or the third interlayer insulating layer160. In the region including the second contact plug150, the sidewall insulating layer170may cover side walls of the etch stopping layer130, the second interlayer insulating layer140, the second contact plug150, and/or the third interlayer insulating layer160. Also, the sidewall insulating layer170may completely cover and/or fill the fourth opening164by covering side walls of the first interlayer insulating layer110and the second contact plug150, which may be exposed by the fourth opening164. In particular, the sidewall insulating layer170may be formed in such a manner that the sidewall insulating layer170may insulate the second contact plug150from a conductive layer (refer to reference numeral180ofFIG. 11B) that is to be formed in a portion of the third opening162in a subsequent process. Thus, a lower portion of the second contact plug150may have a cross-sectional area larger than that of an upper portion of the second contact plug150, wherein the sidewall insulating layer170may not contact the lower portion of the second contact plug150, while the sidewall insulating layer170may contact the upper part of the second contact plug150. By doing so, an area (that is, the cross-sectional area of the lower part of the second contact plug150) contacting the active region of the substrate100may be relatively large. Thus, an electrical contact area may increase so that electrical resistance may decrease and the number of defects may be reduced. Otherwise, a typical second contact plug (e.g., a storage contact plug) formed according to a self-aligning method after a bit line is formed may have, e.g., a higher resistance and a greater number of defects.

Referring toFIGS. 11A and 11B, a conductive layer180may be formed by filling at least a portion of the third opening162with a third conductive material. The third conductive material may include, e.g., polysilicon, aluminum (Al), gold (Au), beryllium (Be), bismuth (Bi), cobalt (Co), copper (Cu), hafnium (Hf), indium (In), manganese (Mn), molybdenum (Mo), nickel (Ni), lead (Pb), palladium (Pd), platinum (Pt), rhodium (Rh), rhenium (Re), ruthenium (Ru), tantalum (Ta), tellurium (Te), titanium (Ti), tungsten (W), zinc (Zn), and/or zirconium (Zr). The third conductive material may further include a nitride or silicide. If polysilicon is used, it may be doped with n-type impurities or p-type impurities. The conductive layer180may further include a barrier layer (not shown) to lower a potential barrier between contacts. The barrier layer may be a monolayer including, e.g., titanium (Ti), tantalum (Ta), or tungsten (W), or may be a multilayer including, e.g., titanium/titanium nitride (Ti/TiN), tantalum/tantalum nitride (Ta/TaN), or tungsten/tungsten nitride (W/WN). However, materials and layers included in the conductive layer180are not limited to the aforementioned materials and layers. The third conductive material may be the same as or different from the first conductive material and/or the second conductive material.

The conductive layer180may be formed by covering the third opening162with the conductive material and then performing a planarization process and an optional recess process. Alternatively, the conductive layer180may be formed by filling a portion of the area in the third opening162to a height lower than that of the second interlayer insulating layer140. The conductive layer180may be electrically connected to the first contact plug120. The conductive layer180may be electrically insulated from the second contact plug150by the sidewall insulating layer170.

Referring toFIGS. 12A and 12B, a fourth interlayer insulating layer190may be formed on the conductive layer180so as to completely fill remaining portions of the third opening162. The fourth interlayer insulating layer190may serve as a capping layer with respect to the conductive layer180, and may include, e.g., a silicon oxide, a silicon nitride, or a silicon oxynitride. Also, the fourth interlayer insulating layer190may include the same material as or a different material from the third interlayer insulating layer160.

Then, the third interlayer insulating layer160may be removed to expose, e.g., the second contact plug150. The storage capacitor195(seeFIG. 1) may be formed on the second contact plug150, thereby completing the manufacture of the semiconductor device1ofFIG. 1.

The method of manufacturing the semiconductor device according to the embodiment illustrated inFIGS. 2A through 12Bmay involve forming the first contact plug120, including the first conductive material, in the first interlayer insulating layer110on the semiconductor layer100; forming the second interlayer insulating layer140that covers the first interlayer insulating layer110; forming the second contact plug150including the second conductive material in the second interlayer insulating layer140and the first interlayer insulating layer110; forming the third interlayer insulating layer160on the second interlayer insulating layer140; patterning a portion of the second interlayer insulating layer140by using the third interlayer insulating layer160as an etch mask, and thus forming the third opening162that exposes a portion of the second contact plug150; forming the fourth opening164by additionally etching the portion of the second contact plug150exposed by the third opening162in a lower direction; forming the sidewall insulating layer170in the third opening162and the fourth opening164; and forming the conductive layer180by filling at least a portion of an area in the third opening162with the third conductive material.