Selective deposition of germanium

Abstract

Methods for selectively depositing germanium-containing films are disclosed. Some embodiments of the present disclosure provide deposition on bare silicon with little or no deposition on silicon oxide surfaces. Some embodiments of the present disclosure provide conformal films on trench sidewalls. Some embodiments of the present disclosure provide excellent gap filling without seams or voids.

Description

【Technical Field】 【0001】 【0001】Embodiments of the present disclosure relate to a method for selectively depositing a film containing germanium. More specifically, embodiments of the present disclosure are directed to a method for selectively depositing germanium within a substrate feature. 【Background Art】 【0002】 【0002】The semiconductor industry faces many challenges in pursuing device miniaturization, which involves the rapid scaling of nanoscale features. Such problems include the introduction of complex device manufacturing processes involving multiple lithography steps and etching. Furthermore, in the semiconductor industry, low-cost alternatives to high-cost EUV are desired for patterning complex structures. Selective deposition has shown promise in simplifying integration schemes and eliminating costly lithography steps to maintain the progress of device miniaturization and reduce chip manufacturing costs. 【0003】 【0003】Selective deposition of materials can be achieved in various ways. For example, some processes may have a selectivity specific to a surface based on its chemical properties. For example, several methods are known for selectively depositing on silicon or metal surfaces over a dielectric (e.g., silicon oxide). 【0004】

[0004] Furthermore, germanium is a versatile material in semiconductor manufacturing. Silicon-germanium alloys are rapidly becoming an important semiconductor material for high-speed integrated circuits. Circuits that utilize the properties of silicon-silicon-germanium junctions can be much faster than circuits that use silicon alone. Silicon-germanium is also beginning to replace gallium arsenide (GaAs) in many wireless communication devices. Germanium-on-insulator (GeOI) substrates are also seen as a potential alternative to silicon-on-miniature chips. Other applications in electronics include phosphors in fluorescent lamps and solid-state light-emitting diodes (LEDs). 【0005】

[0005] Therefore, there is a need for methods to selectively deposit germanium-containing films and further utilize these materials in increasingly smaller electronic devices. [Overview of the Initiative] 【0006】

[0006] One or more embodiments of the present disclosure relate to a method for selective deposition. The method involves exposing a substrate to a reactive gas containing a germanium precursor to selectively deposit a germanium-containing film on a second material which is substantially oxygen-free and contains silicon and / or germanium, compared to a first material which contains silicon and oxygen. The substrate comprises a plurality of features, each having a depth from top to bottom and a width between two sidewalls. The bottom contains the first material, and the sidewalls contain the second material. 【0007】

[0007] Further embodiments of the present disclosure relate to a method of selective deposition. This method involves exposing a substrate, maintained at a temperature in the range of 500°C to 800°C, to a reactive gas containing Germanine and hydrogen gas to deposit a first material containing silicon and oxygen. Rather The method includes selectively depositing a conformal germanium-containing film on a second material which is substantially silicon. The substrate comprises a plurality of features, each feature consisting of a bottom and two side walls, the bottom comprising the first material and the side walls comprising the second material. 【0008】

[0008] Further embodiments of the present disclosure relate to a bottom-up gap-filling method. The method involves exposing a substrate to a reactive gas containing a germanium precursor to selectively deposit a germanium-containing film on a second material which is substantially oxygen-free and contains silicon and / or germanium, rather than a first material which contains silicon and oxygen. The substrate comprises a plurality of features, each having a depth from top to bottom and a width between two sidewalls. The bottom contains the second material, and the sidewalls contain the first material. 【0009】

[0009] 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 reference to embodiments, some of which are illustrated in the accompanying drawings. However, it should be noted that the accompanying drawings only illustrate typical embodiments of the present disclosure and should not be considered to limit the scope of the present disclosure, as the present disclosure may also permit other equally valid embodiments. [Brief explanation of the drawing] 【0010】 [Figure 1A]

[0010] This is a side view of an exemplary substrate before processing according to one or more embodiments of the present disclosure. [Figure 1B] 【0011】 This is an exemplary top view of a substrate before processing, according to one or more embodiments of the present disclosure. [Figure 2] 【0012】 This is a lateral cross-sectional view of an exemplary substrate being processed according to one or more embodiments of the present disclosure. [Figure 3A] 【0013】 This is a side view of an exemplary substrate before processing according to one or more embodiments of the present disclosure. [Figure 3B] 【0014】 This is an exemplary top view of a substrate before processing, according to one or more embodiments of the present disclosure. [Figure 4] 【0015】 This is a lateral cross-sectional view of an exemplary substrate being processed according to one or more embodiments of the present disclosure. [Modes for carrying out the invention]

[0011] 【0016】 Before describing some exemplary embodiments of this disclosure, it should be understood that this disclosure is not limited to the configuration or process details presented below. Other embodiments of this disclosure are possible and can be implemented or performed in various ways.

[0012] 【0017】 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. Those skilled in the art will also understand that when a substrate is referred to, unless otherwise explicitly stated in the context, it may refer to only a portion of the substrate. Furthermore, when a deposition on a substrate is referred to, it may mean both a bare substrate and a substrate on which one or more films or features are deposited or formed.

[0013] 【0018】In this specification, “substrate” refers to any substrate on which a film treatment is performed during a manufacturing process, or any material surface formed on such a substrate. 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 be exposed to pretreatment processes for polishing, etching, reduction, oxidation, hydroxylation, annealing, UV curing, electron beam (e-beam) curing, and / or baking of the substrate surface. In addition to film treatment directly on the surface of the substrate itself, any of the disclosed film treatment steps may be performed on an underlying layer formed on the substrate, as will be disclosed in more detail below, and the term “substrate surface” is intended to include such underlying layer, 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.

[0014] 【0019】 One or more embodiments of this disclosure relate to methods for selectively depositing germanium-containing films. In some embodiments, the method advantageously provides a method for selectively depositing germanium or a silicon-germanium alloy. In some embodiments, the method advantageously provides conformal germanium-containing films. In some embodiments, the method advantageously provides depositing germanium-containing films on silicon on silicon oxide.

[0015] 【0020】 As used herein and in the appended claims, terms such as “selectively depositing a film on the first surface rather than the second surface” mean that a first amount of film is deposited on the first surface, a second amount of film is deposited on the second surface, the first amount of film is greater than the second amount of film, or no film is deposited on the second surface.

[0016] 【0021】 The term "over" used in this context does not imply the physical orientation of one surface over the other, but rather implies the relationship of the thermodynamic or mechanical properties of the chemical reaction of one surface to the other. For example, selectively depositing a cobalt film on a metal surface over a dielectric surface means that the cobalt film deposits on the metal surface and either a lesser amount or no cobalt film deposits on the dielectric surface, or that the formation of the cobalt film on the metal surface is thermodynamically or mechanically favorable over the formation of the cobalt film on the dielectric surface. 【0017】 【0022】 The selectivity of a deposition process is generally expressed as a multiple of growth rates. For example, if one surface deposits 25 times faster than another surface, the process has a selectivity of 25:1 or is simply described as 25. In this regard, a higher ratio indicates a more selective process. 【0018】 【0023】 Referring to FIGS. 1A, 1B, and 2, an exemplary method 200 uses a substrate 100. For clarity, FIG. 1B shows a top view of the substrate 100. FIG. 1A shows a side cross-sectional view along A - A' shown in FIG. 1B. The substrate 100 includes a first material 110 and a second material 120. 【0019】 【0024】 The substrate 100 includes a plurality of features 130. Each feature 130 has a depth D from the top 132 to the bottom 134 of the feature 130 and a width W between two sidewalls 136, 138. The bottom 134 contains the first material 110 and the sidewalls 136, 138 contain the second material 120. 【0020】 【0025】In some embodiments, as shown in FIG. 1B, each feature 130 is a trench having a length L greater than the width W. In some embodiments, the ratio of the length L to the width W is 2 or more, 5 or more, 10 or more, 20 or more, 50 or more, 100 or more, or 500 or more. In some embodiments not shown in FIG. 1B, the length L of the feature 130 is surrounded by vertical walls. In some embodiments, the length L of the feature 130 is surrounded only by the edge of the substrate 100. 【0021】 【0026】 In some embodiments, the width W of the feature 130 ranges from 10 nm to 100 nm, from 20 nm to 50 nm, from 30 nm to 40 nm, from 10 nm to 50 nm, or from 15 nm to 30 nm. In some embodiments, the width W of the feature 130 is about 20 nm. In some embodiments, the depth D of the feature 130 ranges from 5 nm to 100 nm, from 10 nm to 50 nm, or from 15 nm to 30 nm. In some embodiments, the ratio of the depth D to the width W (i.e., the aspect ratio) ranges from 0.1 to 10, from 0.25 to 4, from 0.5 to 2, or from 0.5 to 1. In some embodiments, the depth D is greater than the width W, and the aspect ratio ranges from 1 to 20, from 2 to 20, from 5 to 20, or from 10 to 20. 【0022】 【0027】 The first material 110 includes silicon and oxygen. In some embodiments, the first material includes one or more of SiO, SiOC, SiON, or SiOCN. In some embodiments, the first material 110 consists essentially of silicon oxide. In some embodiments, the first material consists essentially of silicon dioxide (SiO2). 【0023】 【0028】Unless otherwise stated, the material compositions identified in this disclosure and the appended claims do not assume any specific ratio of the identified elements. For example, SiO or silicon oxide should be understood as any material containing silicon and oxygen without assuming a specific ratio of silicon to oxygen. In contrast, SiO2 should be understood as a material containing silicon and oxygen in an atomic ratio of 1:2, respectively. As used herein, a material "substantially consisting of" an identified material includes materials described on an atomic basis of more than 95%, more than 98%, more than 99%, or more than 99.5%.

[0024] 【0029】 The second material 120 comprises substantially oxygen-free silicon and / or germanium. When used in this respect, a material “substantially oxygen-free” has less than 2%, less than 1%, or less than 0.5% oxygen on an atomic basis. In some embodiments, the second material 120 consists substantially of Si, Ge, or SiGe.

[0025] 【0030】 Referring to Figure 2, Method 200 includes exposing the substrate 100 to a reactive gas containing a germanium precursor to selectively deposit a germanium-containing film 250 on the second material 120 on the first material 110.

[0026] 【0031】 In some embodiments, the germanium precursor contains or is substantially composed of germane (GeH4). In some embodiments, the germanium precursor contains one or more of germane, digermane, isobutylgermane, chlorogermane, or dichlorogermane.

[0027] 【0032】In some embodiments, the reactive gas further comprises hydrogen gas (H2). In some embodiments, the hydrogen gas is used as a carrier or diluent for the germanium precursor. In some embodiments, the reactive gas comprises or substantially consists of german and hydrogen gas. In some embodiments, the mole percent of german in the reactive gas is in the range of 1% to 50%, 2% to 30%, or 5% to 20%.

[0028] 【0033】 In some embodiments, the germanium-containing film 250 contains 50% or more of germanium as an atomic percentage. In this respect, the germanium-containing film 250 may be described as a "germanium-rich film." In some embodiments, the atomic percentage of germanium in the germanium-containing film 250 is 60% or more, 70% or more, 80% or more, 90% or more, 95% or more, 98% or more, 99% or more, or 99.5% or more. In other words, in some embodiments, the germanium-containing film 250 consists substantially of germanium.

[0029] 【0034】 In some embodiments, the germanium-containing film 250 includes silicon and germanium. In other words, in some embodiments, the germanium-containing film 250 includes SiGe.

[0030] 【0035】 In some embodiments, if the germanium-containing film 250 contains silicon, the reactive gas further contains a silicon-containing precursor. In some embodiments, the silicon-containing precursor contains one or more of silane (SiH4), polysilane, or halosilane. In this regard, "polysilane" is a compound of the general formula SiH4. n H 2n+2 It is a species having (n is from 2 to 6). Furthermore, "Halosiran" has the general formula Si a X b H 2a+2-b The species has (where X is a halogen, a is from 1 to 6, and b is from 1 to 2a+2). In some embodiments, the silicon-containing precursor is SiH4, Si2H6, Si3H8, Si4H 10It contains one or more of SiCl4 or SiH2Cl2.

[0031] 【0036】 In some embodiments, the germanium-containing film 250 is selectively deposited on the second material on the first material. In some embodiments, the selectivity is 5 or greater, 10 or greater, 20 or greater, 30 or greater, or 50 or greater. In some embodiments, the germanium-containing film 250 can be deposited on the second material 120 to a thickness before deposition is observed on the first material 110. In some embodiments, a germanium-containing film 250 exceeding 50 nm, exceeding 100 nm, exceeding 150 nm, exceeding 200 nm, or exceeding 250 nm is deposited on the second material 120 before a 5 nm film is deposited on the first material 110.

[0032] 【0037】 The temperature of the substrate 100 can be maintained during processing. In some embodiments, the substrate 100 is maintained at a temperature in the range of 300°C to 800°C, 400°C to 800°C, 500°C to 800°C, 250°C to 600°C, 400°C to 600°C, or 500°C to 600°C. In some embodiments, the substrate is maintained at approximately 540°C.

[0033] 【0038】 The pressure in the processing chamber can be maintained during processing. In some embodiments, the pressure is maintained in the range of 1 Torr to 300 Torr, 10 Torr to 300 Torr, 50 Torr to 300 Torr, 100 Torr to 300 Torr, 200 Torr to 300 Torr, or 1 Torr to 20 Torr. In some embodiments, the pressure is maintained at approximately 13 Torr.

[0034] 【0039】In some embodiments, the substrate 100 is pre-treated before exposure to the reactive gas. In some embodiments, the native oxide layer is removed from the second material 120 before the substrate 100 is exposed to the reactive gas. In some embodiments, the native oxide is removed by exposing the substrate 100 to a plasma formed from a plasma gas. In some embodiments, the plasma gas contains or consists substantially of hydrogen gas (H2). In some embodiments, the plasma gas contains ammonia (NH3) or nitrogen gas (N2). In some embodiments, the plasma gas consists substantially of nitrogen gas (N2) and hydrogen gas (H2). In some embodiments, the plasma gas consists substantially of ammonia (NH3) and hydrogen gas (H2).

[0035] 【0040】 In some embodiments, the ratio of nitrogen gas or ammonia to hydrogen gas can be controlled. In some embodiments, the ratio (N / H) is in the range of 5 to 0.5 or 2 to 1.

[0036] 【0041】 In some embodiments, the germanium-containing film 250 is substantially conformal on the second material 120 of the substrate 100. As used in this regard, a film is "substantially conformal" if the thickness of the film at all points is within 20%, within 10%, or between 10% and 20% of the average thickness of the film.

[0037] 【0042】 In some embodiments, the germanium-containing film 250 has low roughness. In some embodiments, the surface roughness of the germanium-containing film 250 is 1 nm (Rms) or less.

[0038] 【0043】While not bound by theory, films deposited within features are generally considered to be of lower quality than blanket films. However, when features are small vias, the difference in film quality is not immediately noticeable and does not pose a problem. However, when features are expanded into trenches, the degradation in film quality can become more apparent. Therefore, the inventors found that the film quality of germanium-containing films deposited within trenches by the disclosed method is remarkably superior.

[0039] 【0044】 Referring to Figures 3A, 3B, and 4, a similar method 400 is disclosed in which the first material 110 and the second material 120 are exchanged from a point of position. The bottom 134 of feature 130 contains the second material 120, and the side walls 136, 138 contain the first material.

[0040] 【0045】 Referring to Figure 4, the germanium-containing film 250 is selectively deposited on the second material 120 on the first material 110. In this configuration, the film forms gap fillers within features 130, which are deposited from the bottom 134 toward the top 132. This process can be referred to as a bottom-up gap-filling process.

[0041] 【0046】 While not bound by theory, the bottom-up gap-filling process disclosed herein is considered to favorably provide a germanium-containing film (gap-filling) without the possibility of forming seams, voids, or other film irregularities within feature 130.

[0042] 【0047】Throughout this specification, any reference to “one embodiment,” “a particular embodiment,” “one or more embodiments,” or “a certain 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, phrases such as “in one or more embodiments,” “in a particular embodiment,” “in one embodiment,” or “in a certain embodiment” appearing in various places throughout 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 optimal manner in one or more embodiments.

[0043] 【0048】 While the disclosure herein is described with reference to specific embodiments, those skilled in the art will understand that the embodiments described are merely illustrative of the principles and uses of the disclosure. It will be obvious to those skilled in the art that various modifications and alterations can be made to the methods and apparatus of the disclosure without departing from the essence and scope of the disclosure. Accordingly, the disclosure may include modifications and alterations within the scope of the appended claims and their equivalents.

Claims

[Claim 1] A method for selective deposition, comprising: exposing a substrate maintained at a temperature in the range of 500°C to 800°C to a reactive gas containing a germanium precursor to a second material substantially free of oxygen and containing silicon and / or germanium, wherein the germanium precursor contains germane, the mole percent of germane in the reactive gas is in the range of 5% to 20%, the substrate comprises a plurality of features, each feature having a depth from top to bottom and a width between two sidewalls, the bottom containing the first material, the sidewalls containing the second material, the selectivity for depositing the germanium-containing film being 5 or more, and the method comprising removing native oxides from the second material of the substrate before exposing the substrate to the reactive gas. [Claim 2] The germanium precursor is hydrogen gas (H ２ The method according to claim 1, which is diluted with ). [Claim 3] The method according to claim 1, wherein the germanium-containing film contains SiGe. [Claim 4] The method according to claim 3, wherein the reactive gas further comprises silane, polysilane, or halosilane. [Claim 5] The method according to claim 1, wherein the germanium-containing film is substantially made of germanium. [Claim 6] The method according to claim 1, wherein the first material includes SiO, SiOC, SiON, or a combination thereof. [Claim 7] The method according to claim 1, wherein the second material is substantially composed of Si, Ge, or SiGe. [Claim 8] The method according to claim 1, wherein the width is in the range of 30 nm to 40 nm. [Claim 9] The method according to claim 1, wherein the depth is in the range of 15 nm to 30 nm. [Claim 10] The method according to claim 1, wherein the ratio of the depth to the width is in the range of 0.5 to 1. [Claim 11] The method according to claim 1, wherein the native oxide is removed by exposing the substrate to a plasma formed from a plasma gas. [Claim 12] The plasma gas is substantially composed of hydrogen gas and ammonia (H ２ / NH ３ ), or hydrogen gas and nitrogen gas (H ２ / N ２ The method according to claim 11, comprising, wherein the N / H ratio is in the range of 5 to 0.

5. [Claim 13] The method according to claim 1, wherein the germanium-containing film is substantially conformal on the second material of the substrate. [Claim 14] The method according to claim 1, wherein the germanium-containing film has a roughness of 1 nm (Rms) or less. [Claim 15] A method for selective deposition, comprising: exposing a substrate maintained at a temperature in the range of 500°C to 800°C to a reactive gas containing Germanine and hydrogen gas to selectively deposit a conformal germanium-containing film on a second material substantially composed of silicon rather than a first material containing silicon and oxygen, wherein the substrate comprises a plurality of features, each feature comprising a bottom and two side walls, the bottom comprising the first material and the side walls comprising the second material, the selectivity for depositing the germanium-containing film being 5 or more, the mole percent of Germanine in the reactive gas being in the range of 5% to 20%, and removing native oxides from the second material of the substrate before exposing the substrate to the reactive gas. [Claim 16] A bottom-up gap-filling method, the method comprising exposing a substrate maintained at a temperature in the range of 500°C to 800°C to a reactive gas containing a germanium precursor to selectively deposit a germanium-containing film on a second material which is substantially oxygen-free and contains silicon and / or germanium, compared to a first material containing silicon and oxygen, wherein the germanium precursor contains germane, the mole percent of germane in the reactive gas is in the range of 5% to 20%, the substrate comprises a plurality of features, each feature having a depth from top to bottom and a width between two side walls, the bottom comprising the second material, the side walls comprising the first material, the selectivity for depositing the germanium-containing film being 5 or more, and the method comprising removing native oxides from the second material of the substrate before exposing the substrate to the reactive gas.

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