Defect-free germanium oxide gap filler

Abstract

A method is disclosed for forming a defect-free gap filler comprising germanium oxide. In some embodiments, the gap filler is deposited by simultaneously exposing the substrate surface to a germanium precursor and an oxidizing agent. The germanium precursor may be flowed intermittently. The substrate may also be exposed to a second oxidizing agent to increase the relative concentration of oxygen in the gap filler.

Description

Technical Field

[0001]

[0001] Embodiments of the present disclosure relate generally to methods for forming germanium oxide materials. In particular, embodiments of the present disclosure relate to methods for forming germanium oxide gap fillers that are free of defects.

Background Art

[0002]

[0002] Germanium oxide is becoming an increasingly important material in semiconductor manufacturing. Since germanium is a Group 14 element like silicon, germanium-containing materials often have similar properties to their silicon-based analogs. With the widespread use of silicon oxide in semiconductor manufacturing, there has been increasing interest in germanium oxide, its properties, and methods for forming germanium oxide materials in various processing schemes.

[0003]

[0003] One scheme of interest is to fill features (e.g., vias, trenches, etc.) of a substrate with a gap filler. Unfortunately, typical gap filling methods often result in gap fillers that contain defects, including seams and voids. Defects can cause multiple problems during downstream processing. These problems are often most clearly demonstrated by etching processes that affect the defects differently than the surrounding gap filler. These defects can also cause the pattern / device containing the gap filler to degrade over time.

[0004]

[0004] Therefore, there is a need for novel methods of depositing gap fillers that do not create seams, voids, or other defects in the deposited material.

Summary of the Invention

[0005]

[0005] One or more embodiments of the present disclosure are directed to a method for depositing a gap filler. The method includes exposing a substrate surface including at least one feature to deposit a gap filler including germanium oxide within at least one feature.germane This includes exposure to a precursor and a first oxidizing agent. At least one feature has an opening width and extends to a certain depth into the substrate. The gap filler is substantially free of voids and seams.

[0006]

[0006] Further embodiments of the present disclosure relate to a method for depositing a gap filler. The method involves a substrate surface including at least one feature being subjected to a continuous flow of a first oxidizer, in order to deposit a gap filler containing germanium oxide within at least one feature. germane This involves exposure to alternating flows of a precursor and a second oxidizing agent. At least the feature has an opening width and extends to a certain depth into the substrate. germane The precursor and the second oxidizer each have a duty cycle of 25% or less. The gap filler is substantially free of voids and seams.

[0007]

[0007] Further embodiments of the present disclosure relate to a method for selectively removing germanium oxide, which includes exposing a germanium oxide layer to a basic aqueous solution.

[0008]

[0008] To enable a detailed understanding of the features of the present disclosure described above, a more specific description of the present disclosure, which has been briefly summarized above, can be obtained by referring to embodiments, some of which are illustrated in the accompanying drawings. However, it should be noted that the accompanying drawings illustrate only typical embodiments of the present disclosure, and since the present disclosure may also permit other equally valid embodiments, the accompanying drawings should not be considered to limit the scope of the present disclosure. [Brief explanation of the drawing]

[0009] [Figure 1] An exemplary substrate having features before processing according to one or more embodiments of the present disclosure is shown. [Figure 2] The following are exemplary substrates after processing for forming gap-filling material according to one or more embodiments of the present disclosure. [Figure 3]The following are exemplary substrates after processing for forming a super-conformal film according to one or more embodiments of the present disclosure. [Modes for carrying out the invention]

[0010]

[0012] Before describing some exemplary embodiments of this disclosure, it should be understood that this disclosure is not limited to the structural or process step details presented in the following description. Other embodiments of this disclosure are possible and can be implemented or performed in a variety of ways.

[0011]

[0013] As used herein and in the appended claims, the term “substrate” refers to a surface or portion of a surface on which a process is performed. As will be obvious to those skilled in the art, when a substrate is mentioned, it may refer only to a portion of the substrate unless otherwise explicitly stated in the context. Furthermore, when a deposition on a substrate is mentioned, it may mean both a bare substrate and a substrate on which one or more films or features are deposited or formed.

[0012]

[0014] As used herein, “substrate” refers to any substrate or material surface formed on a substrate on which a film treatment is performed during the manufacturing process. For example, substrate surfaces on which treatment may be performed include, depending on the application, materials such as silicon, silicon oxide, strained silicon, silicon-on-insulator (SOI), carbon-doped silicon oxide, amorphous silicon, doped silicon, germanium, gallium arsenide, glass, sapphire, and any other materials such as metals, metal nitrides, metal alloys, and other conductive materials. A substrate includes, but is not limited to, a semiconductor wafer. A substrate may undergo pretreatment processes to polish, etch, reduce, oxidize, hydroxylate, anneal, UV cure, electron beam (e-beam) cure, and / or bake the substrate surface. In addition to performing film treatment directly on the substrate surface itself, in this disclosure any of the disclosed film treatment steps may also be performed on underlying layers formed on the substrate, as will be described in more detail later. The term “substrate surface” is intended to include such underlying layers, as the context indicates. Therefore, for example, if a film / layer or partial film / layer is deposited on the substrate surface, the exposed surface of the newly deposited film / layer becomes the substrate surface.

[0013]

[0015] Figure 1 shows a cross-sectional view of a substrate 100 having a feature 110. This disclosure relates to a substrate and a substrate surface having at least one feature. Although Figure 1 shows a substrate 100 having a single feature 110 for illustrative purposes, those skilled in the art will understand that two or more features may be present. The shape of the feature 110 may be any suitable shape, including, but not limited to, a trench, a cylindrical via, or a rectangular via.

[0014]

[0016] When used in this context, the term "feature" refers to any intentional irregularity of a surface. Suitable embodiments of a feature include, non-limitingly, a trench having a top, two sidewalls, and a bottom, as well as a peak having a top and two sidewalls but no bottom. As described below, a feature may have any suitable aspect ratio (the ratio of the feature's depth to its width).

[0015]

[0017] The substrate 100 has a substrate surface 120. At least one feature 110 forms an opening within the substrate surface 120. The feature 110 extends to a depth D from the substrate surface 120 (also called the top surface) to the bottom surface 112. The feature 110 has a first side wall 114 and a second side wall 116. The feature shown in Figure 1 has parallel side walls 114, 116, but the width of the feature is most often defined by the width W of the feature at the upper opening of the feature 110. This measurement may also be called the opening width. The open area formed by the side walls 114, 116 and the bottom 112 is also called the gap.

[0016]

[0018] One or more embodiments of this disclosure relate to methods for depositing substantially defect-free void fillers. Some embodiments of this disclosure deposit void fillers that are substantially free of (one or more) seams. Some embodiments of this disclosure deposit void fillers that are substantially free of (one or more) voids. Some embodiments of this disclosure advantageously deposit void fillers without plasma. Some embodiments of this disclosure advantageously deposit void fillers without using another densification step.

[0017]

[0019] One or more embodiments of the present disclosure are directed to a method for depositing a superconformal film. Some embodiments of the present disclosure deposit a superconformal film having a greater thickness on sidewalls and / or lower portions than on upper surfaces. Some embodiments of the present disclosure advantageously deposit a superconformal film without plasma. Some embodiments of the present disclosure advantageously deposit a superconformal film without using another etching process.

[0018]

[0020] Referring to FIG. 2, some embodiments of the present disclosure relate to a method for depositing a gap filler 210 within a feature 110 of a substrate 100. In some embodiments, the gap filler 210 is substantially free of defects including, but not limited to, seams and voids. In some embodiments, the gap filler 210 is substantially free of seams. In some embodiments, the gap filler 210 is substantially free of voids.

[0019]

[0021] As used herein and in the appended claims, a seam is a gap or crack formed within a feature between the sidewalls of the feature 110, but not necessarily centered between two sidewalls. Without being bound by theory, a seam may be formed when the lattice structure of a film grown from the sidewalls of a feature does not match up when meeting near the center of the feature.

[0020]

[0022] As used herein and in the appended claims, a void is an empty area where the gap filler 210 did not deposit within the feature 110. Without being bound by theory, voids are often formed when material deposits faster near the top of the feature and blocks the opening of the feature before the gap filler can completely fill the feature. The remaining unfilled space is the void.

[0021]

[0023] When used in this regard, the terms "substantially free of seams" or "substantially free of voids" mean that any crystalline irregularities or closed spaces in which there is no material formed within the space between the sidewalls of the feature are less than about 1% of the cross-sectional area of the feature.

[0022]

[0024] Referring to FIG. 3, some embodiments of the present disclosure relate to depositing a superconformal film 310 within a feature 110 of a substrate 100. The superconformal film 310 has an upper thickness T on the substrate surface 120 outside the feature 110 greater than the sidewall thickness T on sidewalls 114, 116 S and / or a lower thickness T on the bottom surface 112. B In some embodiments, the ratio between T S and T T is 1.2 or more, 1.5 or more, 2 or more, 3 or more, or 4 or more. In some embodiments, the ratio between T B and T T is 1.2 or more, 1.5 or more, 2 or more, 3 or more, or 4 or more.

[0023]

[0025] A method for depositing a gap filler 210 includes exposing a substrate 100 and a substrate surface 120 including at least one feature 110 to a precursor and a first oxidant to deposit the gap filler 210 within the feature 110. The gap filler 210 includes germanium oxide. germane

[0024]

[0026] A method for depositing a superconformal film 310 includes exposing a substrate 100 and a substrate surface 120 including at least one feature 110 to a precursor and a first oxidant to deposit the superconformal film 310 within the feature 110. The superconformal film 310 includes germanium oxide. germane

[0025]

[0025]

[0027] ​The methods for depositing the gap-filling material 210 and the methods for depositing the superconformal film 310 are similar in several respects. The remainder of this disclosure provides further details about these processes. Unless otherwise explicitly stated, the details provided relate to both the deposit of the gap-filling material 210 and the superconformal film 310.

[0026]

[0028] In the deposition of the gap filler 210, in some embodiments, the feature 110 has an aperture width in the range of 10 nm to 30 nm, 10 nm to 20 nm, 15 nm to 30 nm, 20 nm to 30 nm, or 25 nm to 30 nm. In some embodiments, the feature 110 has an aspect ratio (depth divided by aperture width) in the range of 2 to 10, 2 to 5, or 5 to 10. In some embodiments, the aspect ratio is in the range of 2.5 to 3.5 or 7.5 to 8.5.

[0027]

[0029] Without being constrained by theory, it is thought that the gap filler 210 is slightly fluid and susceptible to capillary forces when deposited on a feature with a narrower opening width. A narrower opening increases the likelihood that the gap filler 210 will be drawn into the feature 110 to form a gap filler 210 that is substantially free of seams or voids.

[0028]

[0030] In the deposition of the superconformal film 310, in some embodiments, the feature 110 has aperture widths in the range of 50 nm to 200 nm, 80 nm to 120 nm, 50 nm to 100 nm, or 100 nm to 200 nm. In some embodiments, the feature 110 has an aspect ratio (depth divided by aperture width) in the range of 2 to 10, 2 to 5, or 5 to 10. In some embodiments, the aspect ratio is in the range of 4.5 to 5.5.

[0029]

[0031] In contrast to the gap filler 210, the superconformal film 310 is typically deposited on features with relatively wide openings. This wider width reduces the capillary effect experienced by the superconformal film 310, allowing it to remain on each feature surface without flowing under the feature 110.

[0030]

[0032] The substrate 100 or the substrate surface 120 is germane The precursor and the first oxidizing agent are exposed simultaneously. In this regard, in order to deposit the gap filler 210 and / or the superconformal film 310, germane Those skilled in the art will understand that the precursor and the first oxidizing agent will react in the gas phase.

[0031]

[0033] germane The precursor may contain any suitable compound for depositing the germanium oxide gap filler. In some embodiments, germane The precursor contains one or more of the following: germane (GeH4) and / or digermane (Ge2H6).

[0032]

[0034] In some embodiments, germane The precursor further contains hydrogen gas (H2). In some embodiments, the ratio of hydrogen gas to German is in the range of 5 to 20, 7 to 15, or 8 to 12. In some embodiments, germane The precursor essentially consists of 10% Germanic gas in hydrogen gas. When used in this context, a process gas "essentially consisting of" the stated gas or mixture of gases includes, on a molar basis, more than 95%, more than 98%, more than 99%, or more than 99.5% of the stated gas or mixture of gases, excluding any inert carriers or diluent gases.

[0033]

[0035] The first oxidizing agent may be any oxygen-supplying compound capable of supplying oxygen atoms to the germanium oxide gap filler. In some embodiments, the first oxidizing agent comprises one or more of nitrous oxide (N2O), oxygen gas (O2), ozone (O3), or water (H2O). In some embodiments, the first oxidizing agent consists essentially of nitrous oxide (N2O).

[0034]

[0036] In some embodiments, germane The ratio of the precursor to the first oxidizing agent is controlled. In some embodiments, when depositing the gap filler 210, germane The ratio of the first oxidizing agent to the precursor is in the range of 5 to 200, 10 to 100, 10 to 50, or 30 to 50. In some embodiments, when depositing the superconformal film 310, germane The ratio of the first oxidizing agent to the precursor is in the range of 50 to 2000, 100 to 1000, 100 to 500, or 300 to 500.

[0035]

[0037] In some embodiments, the substrate 100 or the substrate surface 120 is continuously exposed to a first oxidizing agent. germane The precursor is intermittently exposed. In other words, in some embodiments, the method is a pulsed CVD type method. In this case, one reactant is continuously flowed into the chamber, and the other reactant is flowed in pulses at regular intervals. In some embodiments, the substrate 100 or the substrate surface 120 is exposed to the first oxidizing agent and germane The precursor is exposed to the first oxidizing agent for a period of time prior to simultaneous exposure to the precursor.

[0036]

[0038] germane When the precursor is flowed intermittently or in a pulsed manner, germane The proportion of time during which the precursor flow is active may be described as a duty cycle. In some embodiments, germane The duty cycle of the precursor is 50% or less, 33% or less, 25% or less, or 10% or less.

[0037]

[0039] The length of the deposition cycle may be any suitable length. In some embodiments, the cycle length is in the range of 10 to 60 seconds, or 15 to 50 seconds. Therefore, germane The length of the precursor pulse ranges from 1 second to 30 seconds.

[0038]

[0040] In some embodiments, germane When the precursor is not flowing, the substrate 100 or the substrate surface 120 is exposed to a second oxidizing agent. In some embodiments, the first and second oxidizing agents differ in composition. In some embodiments, the second oxidizing agent comprises one or more of nitrous oxide (N2O), oxygen gas (O2), ozone (O3), or water (H2O). In some embodiments, the first oxidizing agent consists essentially of nitrous oxide (N2O), and the second oxidizing agent consists essentially of oxygen gas (O2).

[0039]

[0041] In some embodiments, germane The exposure times to the precursor and the second oxidizing agent are approximately equal. In some embodiments, germane The precursor and the second oxidizing agent are separated by a period of approximately the same length. In some embodiments, the substrate is subjected to a continuous flow of the first oxidizing agent over a 25% deposition cycle. germane The material is exposed to a deposition cycle that includes a precursor pulse, a first pause over a 25% deposition cycle, a second oxidizer pulse over a 25% deposition cycle, and a second pause over a 25% deposition cycle.

[0040]

[0042] In some embodiments, a method for depositing a gap filler 210 is performed without the use of plasma. In some embodiments, a method for depositing a superconformal film 310 is performed without the use of plasma. In other words, the methods of the present disclosure are thermal processes that do not involve plasma-based reactants.

[0041]

[0043] The pressure of the processing environment may also be controlled. In some embodiments, the method is performed at pressures ranging from 100 Torr to 500 Torr, from 200 Torr to 500 Torr, from 250 Torr to 400 Torr, or from 280 Torr to 350 Torr.

[0042]

[0044] The temperature of the substrate 100 may also be controlled. In some embodiments, the substrate 100 is maintained at a temperature in the range of 400°C to 600°C, 450°C to 550°C, 400°C to 500°C, or 500°C to 600°C.

[0043]

[0045] The gap filler 210 and the superconformal film 310 share several similar material properties. In some embodiments, the atomic ratio of germanium to oxygen is in the range of 0.2 to 1, 0.2 to 0.5, 0.5 to 1, 0.7 to 1, or 0.7 to 0.9.

[0044]

[0046] Without being constrained by theory, the use of the second oxidizing agent as described above is thought to increase the relative oxygen content of the germanium oxide material. Therefore, the gap filler 210 or superconformal film 310 deposited by the disclosed method will have a relatively low atomic ratio of germanium to oxygen when the second oxidizing agent is used.

[0045]

[0047] One or more embodiments of this disclosure relate to methods for removing or etching germanium oxide. In some embodiments, germanium oxide is selectively removed. When used in this context, a selective removal process is one in which the target material (e.g., germanium oxide) is removed more rapidly than the surrounding material. In some embodiments, the method for removing germanium oxide is selective to one or more of silicon oxide or silicon nitride. In some embodiments, the selectivity (GeO xThe etching rate (etching rate of SiO or SiN) is 10 or greater, 20 or greater, 50 or greater, or 100 or greater.

[0046]

[0048] In some embodiments, a method for removing germanium oxide includes exposing germanium oxide to an aqueous solution. In some embodiments, the aqueous solution further comprises hydrogen peroxide (H2O2).

[0047]

[0049] In some embodiments, the aqueous solution is acidic. In some embodiments, the aqueous solution contains sulfuric acid (H2SO4). In some embodiments, the aqueous solution is basic. In some embodiments, the aqueous solution contains one or more of NaOH or NH4OH. In some embodiments, the aqueous solution essentially consists of 0.05 M NaOH.

[0048]

[0050] In some embodiments, the aqueous solution is heated to facilitate the removal of germanium oxide. In some embodiments, the aqueous solution is heated to a temperature in the range of 60°C to 100°C, 70°C to 90°C, 65°C to 75°C, or 85°C to 95°C.

[0049]

[0051] Throughout this specification, any reference to “one embodiment,” “certain embodiments,” “one or more embodiments,” or “an embodiment” means that a particular feature, structure, material, or property described in relation to an embodiment is included in at least one embodiment of this disclosure. Therefore, expressions such as “in one or more embodiments,” “in a particular embodiment,” “in one embodiment,” or “in an embodiment” in various parts of this specification do not necessarily refer to the same embodiment of this disclosure. Furthermore, particular features, structures, materials, or properties may be combined in any suitable manner in one or more embodiments.

[0050]

[0052] While the disclosure herein is described with reference to specific embodiments, it should be understood that these embodiments are merely illustrative of the principles and uses of the disclosure. It will be apparent to those skilled in the art that various modifications and variations can be made to the methods and apparatus of the disclosure without departing from the spirit and scope of the disclosure. Therefore, the present invention is intended to include modifications and variations contained in the accompanying claims and equivalents.

Claims

1. A method for depositing a gap filler, comprising exposing the substrate surface containing at least one feature to a Germanine precursor and a first oxidizing agent in order to deposit a gap filler containing germanium oxide within at least one feature, wherein the at least one feature has an opening width and extends to a certain depth into the substrate, and the gap filler is substantially free of voids and seams. The substrate surface is continuously exposed to the first oxidizing agent and intermittently exposed to the German precursor, and the method is performed without the use of plasma.

2. The method according to claim 1, wherein the aperture width is in the range of 15 nm to 30 nm.

3. The method according to claim 1, wherein the ratio between the depth and the opening width is in the range of 2 to 10.

4. The aforementioned Germanine precursor is Germanine (GeH 4 The method according to claim 1, including )

5. The aforementioned Germanian precursor is hydrogen gas (H 2 The method according to claim 4, further comprising:

6. The method according to claim 5, wherein the ratio of hydrogen gas to Germanic gas is in the range of 5 to 20.

7. The first oxidizing agent is nitrous oxide (N 2 O), oxygen gas (O 2 ), ozone (O 3 ), or water (H 2 The method according to claim 1, comprising one or more of O).

8. The method according to claim 1, wherein the ratio of the first oxidizing agent to the German precursor is in the range of 10 to 50.

9. The method according to claim 1, wherein the method is performed at a pressure in the range of 100 Torr to 500 Torr.

10. The method according to claim 1, wherein the substrate is maintained at a temperature in the range of 400°C to 600°C.

11. The method according to claim 1, wherein the gap filler has an atomic ratio of germanium to oxygen in the range of 0.5 to 1.

12. The method according to claim 1, wherein the Germanine precursor has a duty cycle of 33% or less.

13. The method according to claim 1, further comprising exposing the substrate surface to a second oxidizing agent while the German precursor is not flowing.

14. The first oxidizing agent is N 2 Essentially consisting of O, the second oxidizing agent is O 2 The method according to claim 13, which essentially consists of the above.

15. The method according to claim 13, wherein the gap filler has an atomic ratio of germanium to oxygen in the range of 0.2 to 0.

5.

16. The first oxidizing agent is N 2 O and consists essentially of, the method according to claim 1.

17. A method for depositing a gap filler, comprising exposing the substrate surface containing the at least one feature to a continuous flow of a first oxidizer and an alternating flow of a germanium oxide precursor and a second oxidizer in order to deposit a germanium oxide-containing gap filler within the at least one feature, wherein the at least one feature has an opening width and extends to a certain depth into the substrate, the germanium oxide precursor and the second oxidizer each have a duty cycle of 25% or less, and the gap filler is substantially free of voids and seams.

18. The first oxidizing agent is N 2 Essentially consisting of O, the second oxidizing agent is O 2 The method according to claim 17, comprising essentially the above.

19. A method for depositing a gap filler, comprising exposing the substrate surface containing at least one feature to a Germanine precursor and a first oxidizing agent in order to deposit a gap filler containing germanium oxide within at least one feature, wherein the at least one feature has an opening width and extends to a certain depth into the substrate, and the gap filler is substantially free of voids and seams. The aforementioned Germanine precursor is Germanine (GeH 4 ) and hydrogen gas (H 2 Methods including )

20. The method according to claim 19, wherein the ratio of the hydrogen gas to the Germanic gas is in the range of 5 to 20.

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