Defect-free germanium oxide gap fill

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] FIELD OF THE DISCLOSURE

[0001] Embodiments of the present disclosure generally relate to methods for forming germanium oxide materials. In particular, embodiments of the present disclosure relate to methods for forming defect-free germanium oxide gap fills. [Background technology]

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

[0003] One scheme of interest is filling substrate features (e.g., vias, trenches, etc.) with gap fill material. Unfortunately, typical gap fill methods often result in gap fill material that contains defects, including seams and voids. The defects can cause multiple problems during downstream processing. These problems are often most clearly evidenced by the etching process, which affects the defects differently than the surrounding gap fill. These defects can also cause degradation of the pattern / device containing the gap fill material over time.

[0004]

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

[0005] One or more embodiments of the present disclosure are directed to a method for depositing a gap fill material, the method comprising: subjecting a substrate surface including at least one feature to a process for depositing a gap fill material including germanium oxide within the at least one feature;germane The method includes exposing the at least one feature to a precursor and a first oxidizing agent. The at least one feature has an opening width and extends to a depth into the substrate. The gap fill material is substantially void-free and seam-free.

[0006] A further embodiment of the present disclosure is directed to a method for depositing a gap fill material, the method comprising exposing a substrate surface including at least one feature to a continuous flow of a first oxidizer and a second oxidizer to deposit a gap fill material including germanium oxide in the at least one feature. germane The method includes exposing the precursor to alternating flows of a precursor and a second oxidizer. At least the feature has an opening width and extends to a depth into the substrate. germane The precursor and second oxidizer each have a duty cycle of 25% or less. The gap filler is substantially free of voids and seams.

[0007]

[0007] A further embodiment of the present disclosure is directed to a method for selectively removing germanium oxide, the method comprising exposing a germanium oxide layer to an aqueous base.

[0008]

[0008] So that the features of the present disclosure described above may be understood in detail, a more particular description of the present disclosure briefly summarized above may be had by reference to embodiments, some of which are illustrated in the accompanying drawings. It should be noted, however, that the attached drawings illustrate only typical embodiments of the present disclosure, and the present disclosure may admit of other equally effective embodiments, and therefore the attached drawings should not be considered as limiting the scope of the present disclosure. [Brief explanation of the drawings]

[0009] [Figure 1] 1 illustrates an exemplary substrate having features before processing, in accordance with one or more embodiments of the present disclosure. [Figure 2] 1 illustrates an exemplary substrate after processing to form a gap filler in accordance with one or more embodiments of the present disclosure. [Figure 3]1 illustrates an exemplary substrate after processing to form a super-conformal film in accordance with one or more embodiments of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0010]

[0012] Before describing several example embodiments of the present disclosure, it is to be understood that the present disclosure is not limited to the details of structure or process steps set forth in the following description. The present disclosure is capable of other embodiments and of being practiced or carried out in various ways.

[0011]

[0013] The term "substrate," as used herein and in the appended claims, refers to a surface or portion of a surface upon which a process acts. It will also be appreciated by those skilled in the art that when reference is made to a substrate, it may refer to only a portion of the substrate, unless the context clearly dictates otherwise. Furthermore, when reference is made to deposition on a substrate, it may refer to both a bare substrate and a substrate upon which one or more films or features have been 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 a manufacturing process. For example, substrate surfaces on which treatments may be performed include 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, depending on the application. Substrates include, but are not limited to, semiconductor wafers. Substrates 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 processing directly on the substrate surface itself, the present disclosure also contemplates that any of the disclosed film processing steps may be performed on an underlying layer formed on the substrate, as described in more detail below, and the term "substrate surface" is intended to include such underlying layers as the context indicates. Thus, for example, if a film / layer or partial film / layer is being deposited on the substrate surface, the exposed surface of the newly deposited film / layer would be the substrate surface.

[0013]

[0015] FIG. 1 shows a cross-sectional view of a substrate 100 having a feature 110. The present disclosure relates to substrates and substrate surfaces that include at least one feature. While FIG. 1 shows substrate 100 with a single feature 110 for illustrative purposes, one skilled in the art will understand that there may be more than one feature. The shape of feature 110 may be any suitable shape, including, but not limited to, a trench, a cylindrical via, or a rectangular via.

[0014]

[0016] As used in this context, the term "feature" means any intentional surface irregularity. Suitable examples of a feature include, without limitation, a trench having a top, two sidewalls, and a bottom, and a peak having a top and two sidewalls without a bottom. As described below, a feature can have any suitable aspect ratio (the ratio of the depth of the feature to the width of the feature).

[0015]

[0017] Substrate 100 has a substrate surface 120. At least one feature 110 forms an opening in substrate surface 120. Feature 110 extends a depth D from substrate surface 120 (also referred to as a top surface) to a bottom surface 112. Feature 110 has a first sidewall 114 and a second sidewall 116. While the feature shown in FIG. 1 has parallel sidewalls 114, 116, the width of the feature is most often defined by the width W of the feature at the top opening of feature 110. This measurement may also be referred to as the opening width. The open area formed by sidewalls 114, 116 and bottom portion 112 may also be referred to as a gap.

[0016]

[0018] One or more embodiments of the present disclosure are directed to methods for depositing a gap filler that is substantially free of defects. Some embodiments of the present disclosure deposit a gap filler that is substantially free of seam(s). Some embodiments of the present disclosure deposit a gap filler that is substantially free of void(s). Some embodiments of the present disclosure advantageously deposit the gap filler without a plasma. Some embodiments of the present disclosure advantageously deposit the gap filler without using a separate densification step.

[0017]

[0019] One or more embodiments of the present disclosure are directed to methods for depositing superconformal films. Some embodiments of the present disclosure deposit superconformal films having greater thickness on the sidewalls and / or bottom than on top. Some embodiments of the present disclosure advantageously deposit superconformal films without a plasma. Some embodiments of the present disclosure advantageously deposit superconformal films without the use of a separate etching process.

[0018]

[0020] 2 , some embodiments of the present disclosure relate to a method for depositing a gap filler 210 in 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 that forms in a feature 110 between the sidewalls of the feature, but not necessarily in the center between the two sidewalls. Without being bound by theory, a seam may form when the lattice structures of films grown from the sidewalls of the feature do not match when they meet near the center of the feature.

[0020]

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

[0021]

[0023] As used in this context, the terms "substantially seam-free" or "substantially void-free" mean that there is no material formed within the spaces between the sidewalls of the features, and that any crystalline irregular or enclosed spaces account for less than about 1% of the cross-sectional area of ​​the features.

[0022]

[0024] 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 a top thickness T T a sidewall thickness T on the sidewalls 114, 116 that is greater than S and / or a lower thickness T on the lower surface 112 B In some embodiments, T S and T T is 1.2 or greater, 1.5 or greater, 2 or greater, 3 or greater, or 4 or greater. 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] The method for depositing the gap fill material 210 includes: subjecting the substrate 100 and the substrate surface 120, including at least one feature 110, to deposition of the gap fill material 210 within the feature 110; germane The gap filling material 210 includes germanium oxide.

[0024]

[0026] The method for depositing the superconformal film 310 includes: subjecting the substrate 100 and the substrate surface 120, including at least one feature 110, to a process for depositing the superconformal film 310 within the feature 110, comprising: germane The superconformal film 310 includes germanium oxide.

[0025]

[0027] The methods for depositing the gap filler 210 and the methods for depositing the superconformal film 310 are similar in some respects. The remainder of this disclosure provides further details about these processes. Except where expressly specified, the details provided relate to both the deposition of the gap filler 210 and the superconformal film 310.

[0026]

[0028] Upon deposition of gap fill material 210, in some embodiments, features 110 have opening widths 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, features 110 have aspect ratios (depth divided by opening 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 bound by theory, it is believed that the gap filler material 210 is slightly more flowable and susceptible to capillary forces when deposited onto features with narrower opening widths, which increases the likelihood that the gap filler material 210 will be drawn into the features 110 to form gap filler material 210 that is substantially free of seams or voids.

[0028]

[0030] In depositing the superconformal film 310, in some embodiments, the features 110 have opening widths ranging from 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 features 110 have aspect ratios (depth divided by opening width) ranging from 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 fill material 210, the superconformal film 310 is typically deposited on features with a relatively wide opening width. This wider width reduces the capillary effect experienced by the superconformal film 310, allowing the superconformal film 310 to remain on each of the feature surfaces without flowing underneath the feature 110.

[0030]

[0032] The substrate 100 or the substrate surface 120 is germane In this regard, to deposit the gap filler 210 and / or the superconformal film 310, germane Those skilled in the art will appreciate that the precursor and first oxidant will react in the vapor phase.

[0031]

[0033] germane The precursor may include any suitable compound for depositing a germanium oxide gap fill material. In some embodiments, germane The precursors include one or more of germane (GeH4) and / or digermane (Ge2H6).

[0032]

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

[0033]

[0035] The first oxidizer may be any oxygen-donating compound capable of donating oxygen atoms to the germanium oxide gap filler. In some embodiments, the first oxidizer comprises one or more of nitrous oxide (NO), oxygen gas (O), ozone (O), or water (HO). In some embodiments, the first oxidizer consists essentially of nitrous oxide (NO).

[0034]

[0036] In some embodiments, germane The ratio of the precursor to the first oxidizer is controlled. In some embodiments, when depositing the gap fill material 210: germane The ratio of the first oxidizer to the precursor ranges from 5 to 200, from 10 to 100, from 10 to 50, or from 30 to 50. In some embodiments, when depositing the superconformal film 310, germane The ratio of first oxidizer to precursor ranges from 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 substrate 100 or substrate surface 120 is intermittently exposed to the precursor. Stated differently, in some embodiments, the method is a pulsed CVD type method, where one reactant flows continuously into the chamber and the other reactant is pulsed at regular intervals. In some embodiments, the substrate 100 or substrate surface 120 is exposed to a first oxidizing agent and germane It is exposed to a first oxidizing agent for a period of time before being simultaneously exposed to the precursor.

[0036]

[0038] germane When the precursor is flowed intermittently or in pulses, germane The percentage of time that the precursor flow is active may be described as the duty cycle. germane The precursor duty cycle 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 ranges from 10 seconds to 60 seconds, or from 15 seconds to 50 seconds. Thus, germane The precursor pulse length ranges from 1 second to 30 seconds.

[0038]

[0040] In some embodiments, germane When the precursor is not flowing, the substrate 100 or substrate surface 120 is exposed to a second oxidizer. In some embodiments, the first oxidizer and the second oxidizer are compositionally different. In some embodiments, the second oxidizer comprises one or more of nitrous oxide (NO), oxygen gas (O), ozone (O), or water (HO). In some embodiments, the first oxidizer consists essentially of nitrous oxide (NO) and the second oxidizer consists essentially of oxygen gas (O).

[0039]

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

[0040]

[0042] In some embodiments, the method for depositing the gap fill material 210 is performed without the use of a plasma. In some embodiments, the method for depositing the superconformal film 310 is performed without the use of a plasma. Stated differently, the method of the present disclosure is a thermal process in the absence of plasma-based reactants.

[0041]

[0043] The pressure of the processing environment may also be controlled, and in some embodiments, the method is carried out at a pressure in the range of 100 Torr to 500 Torr, in the range of 200 Torr to 500 Torr, in the range of 250 Torr to 400 Torr, or in the range of 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, in the range of 450°C to 550°C, in the range of 400°C to 500°C, or in the range of 500°C to 600°C.

[0043]

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

[0044]

[0046] Without being bound by theory, it is believed that the use of a second oxidizer as described above increases the relative oxygen content of the germanium oxide material, and 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 a second oxidizer is used.

[0045]

[0047] One or more embodiments of the present disclosure are directed to methods of removing or etching germanium oxide. In some embodiments, the germanium oxide is selectively removed. As used in this context, a selective removal process is one in which the target material (e.g., germanium oxide) is removed more quickly 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 of the silicon dioxide film / etching rate of SiO or SiN) is 10 or more, 20 or more, 50 or more, or 100 or more.

[0046]

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

[0047]

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

[0048]

[0050] In some embodiments, the aqueous solution is heated to facilitate removal of germanium oxide, ie, 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, references to "one embodiment," "certain embodiment," "one or more embodiments," or "an embodiment" mean that a particular feature, structure, material, or characteristic described in connection with an embodiment is included in at least one embodiment of the present disclosure. Thus, the appearances of phrases such as "in one or more embodiments," "in a particular embodiment," "in one embodiment," or "in an embodiment" in various places throughout this specification are not necessarily all referring to the same embodiment of the present disclosure. Furthermore, the particular features, structures, materials, or characteristics may be combined in any suitable manner in one or more embodiments.

[0050]

[0052] Although the disclosure herein has been described with reference to particular embodiments, it is to be understood that these embodiments are merely illustrative of the principles and applications of the disclosure. It will be apparent to those skilled in the art that various modifications and variations can be made to the disclosed method and apparatus without departing from the spirit and scope of the disclosure. Thus, it is intended that the present invention cover such modifications and variations as come within the scope of the appended claims and their equivalents.

Claims

1. 1. A method for depositing a gap fill material, comprising: exposing a substrate surface including at least one feature to a germane precursor and a first oxidizing agent to deposit a gap fill material comprising germanium oxide within the at least one feature, the at least one feature having an opening width and extending to a depth into the substrate, the gap fill material being substantially free of voids and seams; The method wherein the substrate surface is continuously exposed to the first oxidizing agent and intermittently exposed to the germane precursor, and is performed without the use of a plasma.

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

3. The method of claim 1 , wherein the ratio between the depth and the opening width ranges from 2 to 10.

4. The germane precursor is germane (GeH 4 10. The method of claim 1, comprising:

5. The germane precursor is hydrogen gas (H 2 5. The method of claim 4, further comprising:

6. 6. The method of claim 5, wherein the ratio of the hydrogen gas to the germane ranges from 5 to 20.

7. The first oxidant is nitrous oxide (N 2 O), oxygen gas (O 2 ), ozone (O 3 ), or water (H 2 0). The method of claim 1, further comprising one or more of:

8. 10. The method of claim 1, wherein the ratio of the first oxidizer to the germane precursor ranges from 10 to 50.

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

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

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

12. 10. The method of claim 1, wherein the germane precursor has a duty cycle of 33% or less.

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

14. The first oxidant is N 2 and the second oxidant consists essentially of O. 2 14. The method of claim 13, consisting essentially of

15. The method of 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 method of claim 1, wherein the first oxidant consists essentially of N2O.

17. A method for depositing a gap filler, comprising exposing a substrate surface including at least one feature to a continuous flow of a first oxidizer and alternating flows of a germane precursor and a second oxidizer to deposit a gap filler including germanium oxide within the at least one feature, the at least one feature having an opening width and extending to a depth into the substrate, the germane precursor and the second oxidizer each having a duty cycle of 25% or less, and the gap filler being substantially free of voids and seams.

18. The first oxidant is N 2 and the second oxidant consists essentially of O. 2 18. The method of claim 17, consisting essentially of 19. A method for depositing a gap filler, comprising exposing a substrate surface including at least one feature to a germanium precursor and a first oxidizer to deposit a gap filler comprising germanium oxide within the at least one feature, the at least one feature having an opening width and extending a depth into the substrate, the gap filler being substantially free of voids and seams; The method wherein the germane precursor comprises germane (GeH 4 ) and hydrogen gas (H 2 ).

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

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