3D nanochannel interleaved devices for molecular manipulation are provided. In one aspect, a method of forming a device includes: forming a pattern on a substrate of alternating mandrels and spacers alongside the mandrels; selectively removing the mandrels from a front portion of the pattern forming gaps between the spacers; selectively removing the spacers from a back portion of the pattern forming gaps between the mandrels; filling i) the gaps between the spacers with a conductor to form first electrodes and ii) the gaps between the mandrels with the conductor to form second electrodes; and etching the mandrels and the spacers in a central portion of the pattern to form a channel (e.g., a nanochannel) between the first electrodes and the second electrodes, wherein the first electrodes and the second electrodes are offset from one another across the channel, i.e., interleaved. A device formed by the method is also provided.

FIELD OF THE INVENTION

The present invention relates to nano-fabricated devices, and more particularly, to three-dimensional (3D) nanochannel interleaved devices for molecular manipulation using dipole moments.

BACKGROUND OF THE INVENTION

Molecular-level control of compounds has important applications in a variety of fields. In medicine, for instance, manipulation of molecules at the molecular level can be used to control the composition of medications. Such a fine-tuned control over the composition of medications can enable the creation of customized medicines and specific dosing. Further, molecular-level control can provide more efficient delivery systems for medications, thus advancing treatment options and efficacy.

However, the ability to effectively manipulate molecules at the molecular level remains challenging and difficult. Technology does not currently exist for production-scale molecular manipulation.

Accordingly, improved techniques for efficient and effective manipulation of molecules at the molecular level would be desirable.

SUMMARY OF THE INVENTION

The present invention provides three-dimensional (3D) nanochannel interleaved devices for molecular manipulation. In one aspect of the invention, a method of forming a device for molecular manipulation is provided. The method includes: forming a pattern on a substrate of alternating mandrels and spacers alongside the mandrels; selectively removing the mandrels from a front portion of the pattern forming gaps between the spacers; selectively removing the spacers from a back portion of the pattern forming gaps between the mandrels; filling i) the gaps between the spacers with a conductor to form first electrodes and ii) the gaps between the mandrels with the conductor to form second electrodes; and etching the mandrels and the spacers in a central portion of the pattern to form a channel (e.g., a nanochannel) between the first electrodes and the second electrodes, wherein the first electrodes and the second electrodes are offset from one another across the channel, i.e., interleaved.

In another aspect of the invention, a device is provided. The device includes: a channel (e.g., a nanochannel); first electrodes disposed in between spacers on a first side of the channel; and second electrodes disposed in between mandrels on a second side of the channel, wherein the first electrodes and the second electrodes are offset from one another across the channel, i.e., interleaved.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Provided herein are three-dimensional (3D) device structures for molecular manipulation that leverage the dipole within the molecule, as well as current nanofabrication techniques to precisely manufacture extremely small features, e.g., dimensions ranging from several micrometers (μm) to 10's of nanometers (nm). Further, the present techniques improve resolution through the interleaving of 3D spirally located electrodes enabling a much finer level of control and manipulation.

Namely, as will be described in detail below, advanced patterning techniques are leveraged herein to place the (interleaved) electrodes for field generation at precise locations at a molecular scale. Advanced etching techniques are used to precisely place channels of a nanoscale size at the center of the electrodes. By ‘interleaved’ it is meant that, instead of being directly opposite one another, the electrodes on opposite sides of the nanochannel are offset from one another.

Advantageously, the present 3D device structures permit the electro-kinetic control of individual molecules using the dipoles inherent in the subject material. For instance, during operation, applying a field selectively to portions of a molecule (via the electrodes) will electrokinetically orient and/or locomote the molecule in the nanochannel as a result of dynamic electric field application. Individual electrodes can be controlled individually and intelligently.

An exemplary methodology for forming a 3D device for molecular manipulation is now described by way of reference toFIGS.1-17. As shown inFIG.1, the process begins with the formation of mandrels104on a substrate102.

According to an exemplary embodiment, substrate102is a bulk semiconductor wafer, such as a bulk silicon (Si), bulk germanium (Ge), bulk silicon germanium (SiGe) and/or bulk III-V semiconductor wafer. Alternatively, substrate102can be a semiconductor-on-insulator (SOI) wafer. A SOI wafer includes an SOI layer separated from an underlying substrate by a buried insulator. When the buried insulator is an oxide it is referred to herein as a buried oxide or BOX. The SOI layer can include any suitable semiconductor, such as Si, Ge, SiGe, and/or a III-V semiconductor. Substrate102may already have pre-built structures (not shown) such as transistors, diodes, capacitors, resistors, isolation regions (e.g., shallow trench isolation (STI) regions), interconnects, wiring, etc.

To form the mandrels104on substrate102, a mandrel layer is first deposited onto the substrate102and then patterned into the individual mandrels104shown inFIG.1. According to an exemplary embodiment, mandrels104are formed from an undoped oxide material. Suitable undoped oxide materials include, but are not limited to, undoped silicon oxide (SiOx). A process such as chemical vapor deposition (CVD), atomic layer deposition (ALD) or physical vapor deposition (PVD) can be used to deposit the mandrel material.

Mandrels104can be patterned using a patterning technique such as lithography followed by an etching process. With a lithography and etching process, a lithographic stack (not shown), e.g., photoresist/organic planarizing layer (OPL)/anti-reflective coating (ARC), is typically used to pattern a hardmask (not shown). The pattern from the hardmask is then transferred to the underlying substrate (in this case the mandrel layer). The hardmask is then removed. Suitable etching processes include, but are not limited to, a directional (anisotropic) etching process such as reactive ion etching (RIE). Alternatively, the mandrels104can be formed by other suitable techniques, including but not limited to, sidewall image transfer (SIT), self-aligned double patterning (SADP), self-aligned quadruple patterning (SAQP), and other self-aligned multiple patterning (SAMP) techniques. It is notable that the patterning of four mandrels104on substrate102in the present embodiment is merely provided as an example meant to illustrate the present techniques. For instance, embodiments are contemplated herein where more or fewer mandrels104than shown are formed on substrate102.

According to an exemplary embodiment, mandrels104have nanoscale dimensions. Advantageously, use of the above-described pitch multiplying techniques such as SIT, SADP, SAQP or SAMP, permits the patterning of mandrels at a sub-lithographic pitch (i.e., a pitch smaller than what is achievable using direct lithography. For instance, in one exemplary embodiment, mandrels104have a height H of from about 20 nanometers (nm) to about 50 nm and ranges therebetween, a width W of from about 5 nm to about 10 nm and ranges therebetween, and a pitch p of from about 10 nm to about 20 nm and ranges therebetween. SeeFIG.1. Pitch is defined as the distance from a given point on one mandrel to the same point on the adjacent mandrel.

Spacers202are then formed on opposite sides of the mandrels104. SeeFIG.2. Preferably, the spacers202are formed from a different material than the mandrels104to provide etch selectivity between the spacers202and the mandrels104. This etch selectivity will be leveraged later on in the process to remove (portions) of the mandrels104selective to the spacers202. As provided above, the mandrels104can be formed from an undoped oxide material such as SiOx. In that case, a nitride material such as silicon nitride (SiN) and/or silicon oxynitride (SiON) can be used for the spacers202to provide etch selectivity vis-à-vis mandrels104.

According to an exemplary embodiment, spacers202are formed by depositing a spacer material (e.g., SiN and/or SiON—see above) onto the mandrels104. A process such as CVD, ALD or PVD can be used to deposit the spacer material. A directional (anisotropic) etching process such as RIE is then used to pattern the spacer material into the individual spacers shown inFIG.2. In one exemplary embodiment, spacers202have a width Wspacer of from about 5 nm to about 10 nm and ranges therebetween.

As shown inFIG.2, following placement of spacers202alongside the mandrels104, there is a space S present between the spacers202alongside adjacent mandrels104. As will be described in detail below, this space S will be filled with additional mandrel material in the next step.

It is notable, that the above-described process of placing mandrels104and then spacers202alongside the mandrel can be repeated (in one or more iterations), if so desired, to achieve denser patterning. In that case, although not explicitly shown in the figures, an oxide-selective etch can be used to remove the mandrels104selective to the spacers202(see above). Additional spacers (not shown) can then be placed alongside spacers202, effectively doubling the pitch of spacers202.

The spaces S between the spacers202alongside adjacent mandrels104are then filled with additional mandrel material, forming mandrels302. SeeFIG.3. According to an exemplary embodiment, mandrels302have the same dimensions (i.e., height, width, pitch, etc.) as mandrels104. For clarity, mandrels104and mandrels302may also be referred to herein as first mandrels and second mandrels, respectively. As provided above, suitable mandrel materials include, but are not limited to, undoped oxide materials such as undoped SiOx. A process such as CVD, ALD or PVD can be used to deposit the mandrel material into the spaces S. Following deposition, the mandrel material can be planarized using a process such as chemical-mechanical polishing (CMP).

As shown inFIG.3, an alternating pattern304of spacers202and mandrels104/mandrels302is now present on the surface of substrate102. Using the configuration above where the spacer material is a nitride material (such as SiN and/or SiON) and the mandrels material is an oxide material (such as undoped SiOx) as an example, an alternating nitride/oxide pattern is now present on the surface of wafer102.

The next task is to selectively remove portions of the mandrels104/mandrels302from a (first) portion402of the pattern304. To do so, a mask406is next formed masking/covering a (second) portion403and a (third) portion404of the pattern. SeeFIG.4. As shown inFIG.4, in the present example, the first portion402encompasses a front portion of the pattern304, the second portion403encompasses a central portion of the pattern304, and the third portion404encompasses a back portion of the pattern304. As will be described in detail below, the first/front portion402and the third/back portion404of the pattern304will be used to form interleaved/offset electrodes of the device. A channel of the device will be formed in the second/central portion403, between the first/front portion402and third/back portion404electrodes.

According to an exemplary embodiment, mask406is formed by depositing a hardmask material onto substrate102over the pattern304. Suitable hardmask materials include, but are not limited to, a carbon-containing hardmask material such as amorphous carbon. Use of a carbon-containing hardmask will enable the removal of mask406selective to the underlying (e.g., nitride) spacers202and (e.g., oxide) mandrels104/mandrels302. The hardmask material can be deposited using a process such as plasma-enhanced CVD (PECVD) or a casting process such as spin coating or spray coating. Lithography and etching techniques (see above) are then employed to pattern the hardmask material into the patterned mask406shown inFIG.4.

An etch is next performed to selectively remove portions of the mandrels104/mandrels302from the first/front portion402of the pattern304. According to an exemplary embodiment, a directional (anisotropic) etching process such as RIE is employed to remove the mandrels104/mandrels302from first/front portion402. As provided above, mandrels104/mandrels302can be formed from an oxide material such as SiOx. In that case, an oxide-selective RIE can be used to remove the portions of the mandrels104/mandrels302from the first/front portion402of pattern304selective to spacers202. Notably, as shown inFIG.4, mask406is present over and protecting the portions of the mandrels104/mandrels302in the second/central portion403and the third/back portion404of the pattern304.

Removal of mandrels104/mandrels302in this manner creates gaps408between the spacers202in the first/front portion402of pattern304. Ultimately, these gaps408will be filled with a conductor to form the electrodes on one side of the channel. However, at this stage in the process, gaps408are first filled with a sacrificial material502. SeeFIG.5. The term ‘sacrificial’ as used herein refers to the notion that material502will be used early on in the process to place a channel spacer, and then later removed and replaced with the electrode conductor. See below. Suitable sacrificial materials include, but are not limited to, amorphous silicon and/or poly-silicon. A process such as CVD, ALD or PVD can be employed to deposit the sacrificial material502into the gaps408. As shown inFIG.5, the deposited sacrificial material502overfills the gaps408and is then planarized to the top of mask406. The sacrificial material502can be planarized using a process such as CMP.

Mask406is next selectively removed from the second/central portion403and third/back portion404of the pattern304exposing the underlying spacers202/mandrels104/mandrels302. SeeFIG.6. As shown inFIG.6, sacrificial material502remains in the first/front portion402of pattern304filling the gaps408between the spacers202. As provided above, mask406can be formed from a carbon-containing hardmask material such as amorphous carbon. Amorphous carbon is an ashable material. Thus, according to an exemplary embodiment, mask406is removed selective to the underlying (e.g., nitride) spacers202and (e.g., oxide) mandrels104/mandrels302using oxygen-containing plasma ashing.

Removal of the mask406enables the placement of a channel spacer702over the second/central portion403of the pattern304adjacent to sacrificial material502. SeeFIG.7. Namely, as provided above, mask406had been present over the second/central portion403and third/back portion404of the pattern304in which a channel and electrodes of the device will be formed, respectively. Removal of the mask406is needed so that the full height channel spacer702(relative to the top of sacrificial material502) can be formed. Suitable materials for the channel spacer702include, but are not limited to carbon-containing spacer materials such as amorphous carbon. Use of a carbon-containing spacer material will enable the selective removal of sacrificial material502(e.g., amorphous silicon and/or poly-silicon) later on in the process (see below). The spacer material can be deposited using a CVD process such as PECVD or a casting process such as spin coating or spray coating. Lithography and etching techniques (see above) can then be employed to pattern the spacer material into the channel spacer702shown inFIG.7.

In one embodiment, the channel of the device has nanoscale dimensions, i.e., the device has a nanochannel. In that case, according to an exemplary embodiment, channel spacer702has a width Wchannel spacer of from about 2 nm to about 10 nm and ranges therebetween. SeeFIG.7.

With sacrificial material502covering the first/front portion402and channel spacer702covering the second/central portion403of pattern304, an etch is next performed to selectively remove portions of the spacers202from the third/back portion404of the pattern304. SeeFIG.8. According to an exemplary embodiment, a directional (anisotropic) etching process such as RIE is employed to remove to the portions of the spacers202from third/back portion404. As provided above, spacers202can be formed from a nitride material such as SiN and/or SiON. In that case, a nitride-selective RIE can be used to remove the portions of spacers202from the third/back portion404of pattern304selective to (e.g., oxide) mandrels104/mandrels302.

Removal of spacers202in this manner creates gaps802between the mandrels104/mandrels302in the third/back portion404of pattern304. Later in the process, these gaps802will be filled with a conductor to form the electrodes on one side of the channel. Notably, the mandrels104/mandrels302in the third/back portion404of pattern304are offset from the spacers202present in the first/front portion402of pattern304. Thus, as will be described in detail below, electrodes formed in the gaps802too will be offset from the electrodes formed (on an opposite side of the channel) in the gaps408(see, e.g.,FIG.4—described above) between spacers202. As highlighted above, having offset or interleaved electrodes is a unique aspect of the present device design that advantageously improves resolution thereby enabling a much finer level of control and manipulation of molecules.

Next, sacrificial material502is selectively removed from the first/front portion402of pattern304and from in between spacers202. SeeFIG.9. As shown inFIG.9, removal of sacrificial material502re-opens gaps408between spacers202. According to an exemplary embodiment, a directional (anisotropic) etching process such as RIE is employed to remove sacrificial material502. As provided above, suitable materials for sacrificial material502include, but are not limited to, amorphous silicon and/or poly-silicon. In that case, a silicon-selective RIE can be used to remove sacrificial material502selective to (e.g., nitride) spacers202, (e.g., oxide) mandrels104/mandrels302, and (e.g., amorphous carbon) channel spacer702.

As shown inFIG.9, channel spacer702remains covering the second/central portion403of pattern304. However, for clarity, if one were to visualize the structure looking through the channel spacer702(seeFIG.10where channel spacer702is shown transparent for illustrative purposes only) it can be seen that the gaps408between spacers202(in the first region402of pattern304) are offset from the gaps802between the mandrels104/mandrels302(in the third region404of pattern304). Thus, when the gaps408and gaps802are filled with a conductor to form electrodes of the device, those electrodes formed in the gaps408and gaps802too will be offset from one another, i.e., interleaved.

Namely, following fromFIG.9, the gaps408between spacers202(in the first/front portion402of pattern304) and the gaps802between the mandrels104/mandrels302(in the third/back portion404of pattern304) are next filled with a conductor1102. SeeFIG.11. Suitable conductors include, but are not limited to, copper (Cu), tungsten (W), cobalt (Co) and/or ruthenium (Ru). A process such as sputtering, evaporation, or electrochemical plating can be employed to deposit conductor1102into the gaps408and the gaps802. As shown inFIG.11, the conductor1102overfills the gaps408and the gaps802and is then planarized to the top of channel spacer702. The conductor1102can be planarized using a process such as CMP.

As shown inFIG.11, the channel spacer702now separates the conductor1102over the first/front portion402from the conductor1102over the third/back portion404of pattern304. The channel spacer702is then selectively removed. SeeFIG.12. As shown inFIG.12, removal of channel spacer702forms a trench1202in between the conductor1102over the first/front portion402and the conductor1102over the third/back portion404of pattern304.

As provided above, channel spacer702can be formed from a carbon-containing spacer material such as amorphous carbon. Amorphous carbon is an ashable material. Thus, according to an exemplary embodiment, channel spacer702is removed selective to conductor1102using oxygen-containing plasma ashing.

Opening of trench1202in conductor1102exposes the underlying portions of spacers202and mandrels104/mandrels302in the second/central portion403of the pattern304. An etch is then used to remove these portions of spacers202and mandrels104/mandrels302through trench1202. SeeFIG.13. As shown inFIG.13, this etch step forms a channel1302in between the first/front portion402and the third/back portion404of the pattern304. According to an exemplary embodiment, a directional (anisotropic) etching process such as RIE is employed for the channel etch. As provided above, the spacers202can be formed from a nitride material, and the mandrels104/mandrels302can be formed from an oxide material. Thus, in that case, an oxide/nitride-selective RIE (or combination of RIE steps) can be used to pattern channel1302through trench1202. Based on the dimensions of channel spacer702(see above), according to an exemplary embodiment, channel1302is a nanochannel having a width of from about 2 nm to about 10 nm and ranges therebetween.

The conductor1102is then recessed. SeeFIG.14. A process such as CMP or a metal-selective etch can be used to recess conductor1102down to spacers202(in the first/front portion402of the pattern304) and mandrels104/mandrels302(in the third/back portion404of the pattern304). Recessing the conductor1102forms an array of electrodes on both sides of the channel1302. Namely, as shown inFIG.14, first electrodes1402are present in between spacers202on a first side of channel1302, and second electrodes1404are present in between mandrels104/mandrels302on a second/opposite side of channel1302.

When viewed from the top-down (i.e., from viewpoint A), it can be seen that the first electrodes1402are offset from second electrodes1404across channel1302. SeeFIG.15. This configuration is what is referred to herein as ‘interleaving’ the electrodes.

For instance, if one were to visualize the structure without the mandrels104/mandrels302and spacers202(seeFIG.16where mandrels104/mandrels302and spacers202are transparent for illustrative purposes only) it can be seen that the first electrodes1402are offset from second electrodes1404across channel1302, i.e., interleaved. According to an exemplary embodiment, each of first/second electrodes1402/1404has a width Welectrode of from about 5 nm to about 10 nm and ranges therebetween, and a height Helectrode of from about 20 nm to about 50 nm and ranges therebetween. SeeFIG.16.

As highlighted above, the present 3D device structures permit the electro-kinetic control of individual molecules using the dipoles inherent in the subject material. See, for example,FIG.17. As is known in the art, polar molecules have a partial negative end and a partial positive end. Dipole-dipole interactions occur when the partial positive end of one molecule is attracted to the partial negative end of another molecule, and vice versa. These interactions can also be used to control the orientation and movement of individual polar molecules with the nanochannel.

For instance, as shown inFIG.17, during operation a field applied selectively to portions of a polar molecule1702will electrokinetically orient (see angle θ) and/or locomote (along x-direction) the polar molecule1702in the channel1302as a result of dynamic electric field applied to the first/second electrodes1402/1404. Polar molecule1702can be present in a fluid medium such as a solvent. Thus, in addition to electrokinetics, a positive pressure of the fluid can also be employed to move molecule1702through channel1302.

Advantageously, first/second electrodes1402/1404can be controlled individually to locomote and/or orient polar molecule1702. See, for example, the electric field being applied dynamically to the electrodes1402/1404on opposite sides of channel1302. Further, as provided above, first/second electrodes1402/1404are offset from one another on opposite sides of the channel1302. Interleaving the electrodes1402/1404in this manner enables a much finer level of control and manipulation of the molecule1702.