Techniques for filling a structure using selective surface modification
10559496 ยท 2020-02-11
Assignee
Inventors
Cpc classification
C23C16/045
CHEMISTRY; METALLURGY
C23C16/52
CHEMISTRY; METALLURGY
C23C16/45536
CHEMISTRY; METALLURGY
H01L21/76825
ELECTRICITY
C23C16/45527
CHEMISTRY; METALLURGY
H01L21/76883
ELECTRICITY
H01L21/76826
ELECTRICITY
H01L21/76814
ELECTRICITY
C23C16/482
CHEMISTRY; METALLURGY
International classification
H01L21/30
ELECTRICITY
C23C16/04
CHEMISTRY; METALLURGY
C23C16/455
CHEMISTRY; METALLURGY
H01L21/02
ELECTRICITY
C23C16/48
CHEMISTRY; METALLURGY
H01L21/768
ELECTRICITY
H01L21/44
ELECTRICITY
H01L21/67
ELECTRICITY
C23C16/52
CHEMISTRY; METALLURGY
Abstract
A method of device processing. The method may include providing a cavity in a layer, directing energetic flux to a bottom surface of the cavity, performing an exposure of the cavity to a moisture-containing ambient, and introducing a fill material in the cavity using an atomic layer deposition (ALD) process, wherein the fill material is selectively deposited on the bottom surface of the cavity with respect to a sidewall of the cavity.
Claims
1. A method of device processing, comprising: providing a cavity in a layer; directing energetic flux to a bottom surface of the cavity, the cavity having a sidewall oriented perpendicularly to the bottom surface, wherein the energetic flux is oriented parallel to the sidewall and does not strike the sidewall of the cavity; performing an exposure of the cavity to a moisture-containing ambient; and introducing a fill material in the cavity using an atomic layer deposition (ALD) process, wherein the fill material forms in layers parallel to the bottom surface, while formation of fill material on the sidewall is suppressed.
2. The method of claim 1, wherein the energetic flux comprises ions, the ions having parallel trajectories.
3. The method of claim 2, wherein the ions comprise trajectories oriented parallel to the sidewall of the cavity.
4. The method of claim 2, wherein the ions comprise an ion energy of 500 eV or less.
5. The method of claim 1, wherein the bottom surface forms an OH-terminated surface after the exposure, and wherein the sidewall does not form an OH-terminated surface after the exposure.
6. The method of claim 1, wherein the fill material is a high dielectric constant material.
7. The method of claim 1, wherein the fill material is a metal.
8. The method of claim 1, wherein the cavity is disposed in a material comprising silicon oxide, silicon nitride, or silicon oxycarbide.
9. The method of claim 1, wherein the energetic flux comprises vacuum ultraviolet photons or electrons.
10. The method of claim 1, wherein the ALD process is performed for a predetermined number of ALD cycles, the method further comprising performing an etch process after the predetermined number of ALD cycles, the etch process being effective to remove a predetermined amount of fill material.
11. The method of claim 10, wherein no fill material is present on exposed regions of the sidewall above a surface of the fill material after the etch process.
12. The method of claim 10, further comprising performing a second ALD process comprising an additional number of ALD cycles after the etch process.
13. The method of claim 9, wherein the energetic flux comprises photons having an energy of 7 eV to 10 eV.
14. The method of claim 1, wherein the fill material partially fills the cavity up to a fill level.
15. The method of claim 14, wherein the fill material is not present on upper portions of the sidewall above the fill level.
16. A method of device processing, comprising: providing a cavity in a layer; directing energetic flux to a bottom surface of the cavity, the cavity having a sidewall oriented perpendicularly to the bottom surface, wherein the energetic flux is oriented parallel to the sidewall and does not strike the sidewall of the cavity; performing an exposure of the cavity to a moisture-containing ambient; and introducing a fill material in the cavity using an atomic layer deposition (ALD) process, wherein the fill material forms in layers parallel to the bottom surface, and wherein the fill material partially fills the cavity up to a fill level.
17. The method of claim 16, wherein the fill material is not present on upper portions of the sidewall above the fill level.
18. The method of claim 16, wherein the energetic flux comprises ions, vacuum ultraviolet photons, or electrons.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
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(9) The drawings are not necessarily to scale. The drawings are merely representations, not intended to portray specific parameters of the disclosure. The drawings are intended to depict exemplary embodiments of the disclosure, and therefore are not be considered as limiting in scope. In the drawings, like numbering represents like elements.
(10) Furthermore, 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 otherwise visible in a true cross-sectional view, for illustrative clarity. Furthermore, for clarity, some reference numbers may be omitted in certain drawings.
DETAILED DESCRIPTION
(11) The present embodiments will now be described more fully hereinafter with reference to the accompanying drawings, where some embodiments are shown. The subject matter of the present disclosure may be embodied in many different forms and are not to be construed as limited to the embodiments set forth herein. These embodiments are provided so this disclosure will be thorough and complete, and will fully convey the scope of the subject matter to those skilled in the art. In the drawings, like numbers refer to like elements throughout.
(12) The embodiments described herein provide novel device processing including processing for filling a cavity, such as a trench or via in a substrate. In various embodiments, techniques are provided for improving trench-fill or via-fill for cavities including high aspect ratio cavities where the aspect ratio is greater than 1. The embodiments are not limited in this context.
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(14) Turning now to
(15) The cavity 100 may have different structure according to various embodiments of the disclosure. In some embodiments, the cavity 100 may have a via structure where the cavity has an oval or circular shape within an X-Y plane according to the Cartesian coordinate system shown. In these embodiments, the sidewall 104 may be just one sidewall defining the side of the cavity 100. In other embodiments, the cavity has a trench structure where the trench includes a pair of opposing sidewalls, shown as the sidewall 104. Additionally, such a trench may include opposing endwalls (not shown). The cavity 100 may also include a bottom surface 102, as shown. In some embodiments, the cavity may have a complex shape within the X-Y plane, such as any targeted trench pattern to be filled.
(16) According to various embodiments, the sidewalls and bottom surface of the cavity 100 may be terminated by surface species 108, such as oxygen. As detailed below, the surface species 108, disposed on the surface of the cavity 100, may be configured to react with certain reactive species provided in a deposition process to facilitate deposition of a target material such as an insulator or metal.
(17) Turning now to
(18) In accordance with various embodiments, the energy of the energetic flux may be arranged to provide adequate energy to alter the surfaces of cavity 100 exposed to the energetic flux, in a manner rendering the surfaces more susceptible to formation of hydroxide (OH) terminations. In embodiments using ions to alter the surface of a cavity, the ion energy of ions may be tailored to provide adequate energy to render impacted surface(s) susceptible to hydroxide formation, while not imparting excessive damage to the impacted surface(s). In some embodiments, the ion energy of ions provided as energetic flux 112 may range between 5 eV and 500 eV. In some embodiments, ions may be provided as inert gas ions including Ar ions, or may be reactive ions, including O.sub.2 ions. In embodiments where photons are used as energetic flux 112, the photons may be provided as ultraviolet phonons in the ultraviolet (UV) energy range or vacuum ultraviolet photons in the vacuum ultraviolet (VUV) energy range. In particular embodiments, the photon energy of photons used as energetic flux 112 may be in the range of 7 eV to 10 eV.
(19) In accordance with embodiments of the disclosure, the cavity 100 may be exposed to a moisture-containing (H.sub.2O) ambient in conjunction with exposure to the energetic flux 112. In various embodiments, the moisture-containing ambient may be provided subsequently to the providing of the energetic flux 112. Turning now to
(20) After selective formation of an OH-terminated surface at the bottom surface 102, according to embodiments of the disclosure, the cavity 100 may be exposed to a deposition process, such as atomic layer deposition (ALD). ALD generally involves sequential exposure to two or more reactants to deposit a given monolayer of material. In various embodiments, an ALD process may be performed to selectively deposit a material such as an oxide, nitride or metal, such as Ta. In some embodiments, the oxide may be a high dielectric constant material, where examples of high dielectric constant materials include Al.sub.2O.sub.3, HfO.sub.2, Ta.sub.2O.sub.5, and other materials where the dielectric constant is greater than the dielectric constant of SiO.sub.2. The embodiments are not limited in this context.
(21) In accordance with embodiments of the disclosure, deposition of the fill material using an ALD process may be selectively promoted on the bottom surface 102 with respect to the sidewalls 104. In particular, the OH-termination of the bottom surface 102 may promote deposition of an aluminum-containing reactant, hafnium-containing reactant, or tantalum-containing reactant, to name certain materials. In different examples, this OH-termination may accordingly result in selective growth of Al.sub.2O.sub.3, HfO.sub.2, Ta.sub.2O.sub.5, or tantalum metal on the bottom surface 102, as opposed to the sidewalls 104. In various embodiments, the given ALD process may be performed in a cyclic fashion to generate bottom-up filling of a given material as suggested by the fill material 120 shown in
(22) By way of further explanation,
(23) Turning now to
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(25) In accordance with additional embodiments of the disclosure, selective deposition of a given material on a targeted surface may be promoted by performing a combination of ALD and etching. In some embodiments, the ALD and etching, such as HF etching, may be performed in a cyclic fashion. The embodiments are not limited in this context.
(26) After 20 ALD cycles, the exposed region subject to UV flux and unexposed region of the substrate are subject to an etch, where the etch removes a target amount of hafnium oxide material. The respective amount of hafnium oxide remaining after etch in the two samples is illustrated by the point 506 and point 508. As shown, no hafnium oxide remains on the unexposed portion after etch, while a hafnium oxide layer remains on the exposed portion. Subsequently, a series of 20 more ALD cycles is performed, followed by a second etch. At the end of this process, no hafnium oxide remains on the unexposed portion, while hafnium oxide remains on the exposed portion. This result is confirmed by the inset figures, showing cross-sectional electron micrographs of UV-exposed samples and unexposed samples at various stages of processing. As illustrated in the upper right inset figure, approximately 3 nm hafnium oxide layer is deposited after 40 ALD cycles in this example.
(27) The above example of
(28) For example, for purposes of illustration, in one scenario after 20 ALD cycles is performed a 4 nm thick layer of fill material may be deposited in a trench, generally in a bottom-up manner, as shown in
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(30) At block 606, an exposure of the cavity to a moisture-containing ambient is performed. According to various embodiments, the exposure to moisture-containing ambient may be conducted after block 604.
(31) At block 608, a fill material is introduced in the cavity using an ALD process, wherein a fill material is selectively deposited on the bottom surface of the cavity with respect to a sidewall of the cavity. In various embodiments, the fill material may constitute an oxide such as a high dielectric constant material, or a metal.
(32) At block 610, an etch process is performed. The etch process may be arranged to remove a predetermined amount of fill material. At decision block 612, a determination is made as to whether the fill process is complete. If so, the flow ends. If not, the flow returns to block 608.
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(34) The system 700 may further include a controller 730 to direct and coordinate transport and processing of a substrate 720, among the different processing chambers of system 700. For example, the controller 730 may include any combination of software and hardware, including logic, memory, and a user interface, to control processing of a substrate among a plurality of processing chambers of the system 700, including plasma immersion chamber 706, moisture chamber 708, ALD chamber 710, and etch chamber 712. As one example, the controller 730 may direct the substrate 720 to be transferred between various process chambers of system 700 in a cyclic process according to a recipe for filling a cavity. A cyclic process may entail transferring the substrate 720 multiple times into and out of a given processing chamber(s), and may entail transferring the substrate 720 between different processing chambers multiple times to complete a cavity fill process. In one specific example of a processing recipe, the substrate 720 may be transported into the UV chamber 714 for a first exposure to energetic photons to alter a bottom surface of cavities within the substrate 720. The substrate 720 may subsequently be transported via transfer chamber 704 to moisture chamber 708 for a second exposure, where the bottom surface of cavities becomes OH-terminated, as described above with respect to
(35) While system 700 may provide one approach involving a cluster tool configuration for performing a cavity fill process in accordance with embodiments of the disclosure, in other embodiments, cavity fill processes may be performed using different apparatus. For example, in some embodiments, a processing apparatus for performing a cavity fill process may include fewer process chambers, such as just one process chamber. In one embodiment, as shown in
(36) The present embodiments provide the advantage of filling narrow trenches and trenches having high aspect ratio without buried voids by favoring growth just on a target surface, such as the bottom of a trench. In addition, the present embodiments provide a further advantage scalability to smaller dimensions, since cavities such as trenches may be filled from the bottom up.
(37) The present disclosure is not to be limited in scope by the specific embodiments described herein. Indeed, other various embodiments of and modifications to the present disclosure, in addition to those described herein, will be apparent to those of ordinary skill in the art from the foregoing description and accompanying drawings. Thus, such other embodiments and modifications are intended to fall within the scope of the present disclosure. Furthermore, the present disclosure has been described herein in the context of a particular implementation in a particular environment for a particular purpose. Those of ordinary skill in the art will recognize the usefulness is not limited thereto and the present disclosure may be beneficially implemented in any number of environments for any number of purposes. Thus, the claims set forth below are to be construed in view of the full breadth and spirit of the present disclosure as described herein.