Method of filling gap on substrate surface using plasma

Abstract

A method of forming a silicon oxide film on a substrate is provided. The method may include the steps of: (a) placing a substrate on a susceptor in a reaction chamber; wherein the substrate comprises a gap; (b) a deposition step comprising: providing a continuous flow of silicon-containing precursor to the reaction chamber; providing a continuous flow of oxidizing gas to the reaction chamber; and depositing a portion of the silicon oxide film on the substrate by providing plasma power to the silicon-containing precursor and the oxidation precursor; and (c) an etching step including: etching a portion of the portion by supplying an etching gas to the reaction chamber; wherein the etching gas is activated by a remote plasma unit, and wherein the remote plasma unit is fluidly coupled to the reaction chamber.

Description

Technical Field

[0001] The present disclosure generally relates to methods of forming structures suitable for fabricating electronic devices. More specifically, examples of the present disclosure relate to methods of filling gaps using plasma on a substrate surface. Background Art

[0002] Chips on wafer are used as part of an advanced 3D packaging process. Several small chips are placed on a large chip or wafer by micro - bumps or direct bonding. In this process, it is necessary to fill the gaps between the small chips. When the width of the gap is between 30um and 650um and the depth of the gap is between 5um and 50um, a plasma - enhanced chemical vapor deposition (PECVD) process can be used to fill the gap.

[0003] Silicon oxide films are commonly used to fill the gaps. Because the step coverage of the PECVD process is not good, an etch sequence may be necessary.

[0004] Therefore, there is a need for improved methods for filling gaps.

[0005] Any discussion set forth in this section, including discussions of problems and solutions, is included in the present disclosure solely to provide background for the present disclosure and should not be taken as an admission that any or all of the discussion was known at the time the invention was made or constitutes prior art. Summary of the Invention

[0006] The Summary of the Invention is provided to introduce some concepts in a simplified form. These concepts are further described in detail in the detailed description of the exemplary embodiments disclosed below. The Summary of the Invention is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter.

[0007] According to an exemplary embodiment of the present disclosure, a method of forming a silicon oxide film on a substrate is provided. The method may include the following steps: (a) placing the substrate on a pedestal in a reaction chamber; wherein the substrate includes a gap; (b) a deposition step, including: providing a continuous flow of a silicon - containing precursor to the reaction chamber; providing a continuous flow of an oxidizing gas to the reaction chamber; and depositing a portion of the silicon oxide film on the substrate by providing plasma power to the silicon - containing precursor and the oxidizing precursor; and (c) an etching step, including: etching locally the portion by providing an etching gas to the reaction chamber; wherein the etching gas is activated by a remote plasma unit, and wherein the remote plasma unit is fluid - coupled to the reaction chamber.

[0008] According to a further example of the present disclosure, the method may further include repeating step (b) and step (c) until the silicon oxide film fills the gap.

[0009] According to a further example of the present disclosure, the silicon-containing precursor may include at least one of the following: SiH4, SiF4, Si2H6, TEOS, TMCTS, OMCTS, DMDMOS, 3MS, 4MS, or a combination thereof.

[0010] According to a further example of the present disclosure, the oxidizing gas may include at least one of the following: O2, O3, N2O, N2O4, NxOy, CO, CO2, H2O, H2O2, or a combination thereof.

[0011] According to a further example of the present disclosure, the etching gas may include a fluorine-containing gas.

[0012] According to a further example of the present disclosure, the flow rate of the etching gas may be between 0.5 and 5 slm.

[0013] According to a further example of the present disclosure, the fluorine-containing gas may include at least one of the following: NF3, C2F6, CF4, or a combination thereof.

[0014] According to a further example of the present disclosure, the fluorine-containing gas may include NF3, and the flow rate of NF3 may be between 3 and 5 slm.

[0015] According to a further example of the present disclosure, steps (b) and (c) may be performed in the same chamber.

[0016] According to a further example of the present disclosure, step (c) may be performed in a second reaction chamber.

[0017] According to a further example of the present disclosure, the pressure for step (b) may be lower than the pressure for step (c).

[0018] According to a further example of the present disclosure, the pressure for step (c) may be between 700 and 900 Pa.

[0019] According to a further example of the present disclosure, the gas may be supplied to the reaction chamber through a shower plate.

[0020] According to a further example of the present disclosure, the gap between the shower plate and the substrate may be narrower during step (c) than during step (b).

[0021] According to a further example of the present disclosure, the distance during step (c) may be between 5.0 mm and 7.0 mm.

[0022] According to a further example of the present disclosure, the width of the gap in the substrate may be between 30 μm and 650 μm, and the depth of the gap may be between 5 μm and 50 μm.

[0023] According to a further example of the present disclosure, a substrate processing apparatus may be provided to perform these steps. Brief Description of the Drawings

[0024] When considered in conjunction with the following illustrative drawings, a more complete understanding of the exemplary embodiments of the present disclosure can be obtained by reference to the detailed description and the claims.

[0025] Figure 1 A method according to an exemplary embodiment of the present disclosure is shown.

[0026] Figure 2 A timing sequence according to an exemplary embodiment of the present disclosure is shown.

[0027] Figure 3a A scanning electron microscope image of the structure after the deposition step is shown.

[0028] Figure 3b A scanning electron microscope image of the structure after the etching step of the structure in Figure 3a by direct plasma is shown.

[0029] Figure 3c A scanning electron microscope image of the structure according to an exemplary embodiment of the present disclosure is shown.

[0030] Figure 4 A graph illustrating the process conditions of the etching step is shown.

[0031] Figure 5 A plasma system according to an exemplary embodiment of the present disclosure is shown.

[0032] It should be understood that the elements in the drawings are shown for simplicity and clarity and are not necessarily drawn to scale. For example, the dimensions of some elements in the figures may be exaggerated relative to other elements to assist in improving the understanding of the illustrated embodiments of the present disclosure. Detailed Description of the Embodiments

[0033] Although certain embodiments and examples are disclosed below, those skilled in the art will understand that the present invention extends beyond the specifically disclosed embodiments and / or uses of the present invention and their obvious modifications and equivalents. Therefore, it is intended that the scope of the present invention as disclosed should not be limited by the specifically disclosed embodiments described below.

[0034] As used herein, the term "substrate" can refer to any one or more underlying materials, including any one or more underlying materials that can be modified or on which a device, circuit, or film can be formed. A "substrate" can be continuous or discontinuous; rigid or flexible; solid or porous; and combinations thereof. A substrate can be in any form, such as a powder, a plate, or a workpiece. A plate-like substrate can include wafers of various shapes and sizes. A substrate can be made of a semiconductor material, including, for example, silicon, silicon germanium, silicon oxide, gallium arsenide, gallium nitride, and silicon carbide.

[0035] For example, a substrate in powder form can be used in pharmaceutical manufacturing. The porous substrate can comprise a polymer. Examples of workpieces can include medical devices (such as stents and syringes), jewelry, tooling equipment, components for battery manufacturing (such as anodes, cathodes, or separators), or components of photovoltaic cells, etc.

[0036] The continuous substrate can extend beyond the boundaries of the processing chamber where the deposition process occurs. In some processes, the continuous substrate can be moved through the processing chamber such that the process continues until the end of the substrate is reached. The continuous substrate can be provided from a continuous substrate feeding system to allow the continuous substrate to be manufactured and output in any suitable form.

[0037] Non-limiting examples of continuous substrates can include sheets, non-woven membranes, rolls, foils, meshes, flexible materials, bundles of continuous filaments or fibers (such as ceramic fibers or polymer fibers). The continuous substrate can also include a carrier or sheet on which a discontinuous substrate is mounted.

[0038] The illustrations presented herein are not meant to be actual views of any particular material, structure, or device, but are merely idealized representations for describing embodiments of the present disclosure.

[0039] The specific embodiments shown and described are illustrative of the invention and its best mode and are not intended to limit the scope of these aspects and embodiments in any way. Indeed, for the sake of brevity, conventional manufacturing, connection, preparation, and other functional aspects of the system may not be described in detail. Additionally, the connecting lines shown in the various figures are intended to represent example functional relationships and / or physical couplings between various elements. Many alternative or additional functional relationships or physical connections may exist in the actual system and / or may not exist in some embodiments.

[0040] It should be understood that the configurations and / or methods described herein are exemplary in nature and these specific embodiments or examples should not be considered limiting as many variations are possible. The specific routines or methods described herein can represent one or more of any number of processing strategies. Accordingly, the various acts shown can be performed in the order shown, in other orders, or in some cases omitted.

[0041] The subject matter of the present disclosure includes all novel and non-obvious combinations and sub-combinations of various processes, systems, and configurations, as well as other features, functions, acts, and / or properties disclosed herein, and any and all equivalents thereof.

[0042] In the present disclosure, "gas" may include materials that are gaseous at normal temperature and pressure, evaporated solids, and / or evaporated liquids, and may consist of a single gas or a gas mixture, depending on the context. Gas introduced without passing through a gas supply unit (such as a shower plate, etc.) may be used, for example, to seal the reaction space and may include a sealing gas, such as a noble gas or other inert gas. The terms inert gas, carrier gas, and diluent gas refer to gases that do not participate in a chemical reaction to a perceptible extent and / or gases that are capable of exciting precursors when plasma power is applied.

[0043] As used herein, the terms "film" and "thin film" may refer to any continuous or discontinuous structure and material deposited by the methods disclosed herein. For example, "film" and "thin film" may include 2D materials, nanorods, nanotubes, or nanoparticles, or even partial or complete molecular layers or partial or complete atomic layers or clusters of atoms and / or molecules. "Film" and "thin film" may include materials or layers having pinholes but are still at least partially continuous.

[0044] Figure 1 A method 100 for forming a silicon oxide film on a substrate according to an exemplary embodiment of the present disclosure is shown. Method 100 includes the following steps: placing the substrate on a pedestal in a reaction chamber (step 101) and a deposition step 102, the deposition step including:

[0045] Providing a continuous flow of a silicon-containing precursor to the reaction chamber (step 104);

[0046] Providing a continuous flow of an oxidizing gas to the reaction chamber (step 106); and depositing a portion of the silicon oxide film on the substrate by applying plasma power to the silicon-containing precursor and the oxidizing precursor (step 108). The method further includes an etching step 121, the etching step including locally etching the portion by providing an etching gas to the reaction chamber. The etching gas may be activated by a remote plasma unit.

[0047] During step 101, the substrate is placed on a pedestal in the reaction chamber. The substrate may include a gap. The width of the gap may be between 30 μm and 650 μm, and the depth of the gap may be between 5 μm and 50 μm. According to an example of the present disclosure, the reaction chamber may form part of a chemical vapor deposition reactor, such as a plasma-enhanced chemical vapor deposition (PECVD) reactor. The various steps of the methods described herein may be performed in a single reaction chamber or may be performed in multiple reaction chambers, such as the reaction chambers of a cluster tool.

[0048] During step 101, the substrate can be brought to a desired temperature and the reaction chamber can be brought to a desired pressure, such as temperatures and pressures suitable for subsequent steps. For example, the temperature in the reaction chamber (such as the temperature of the substrate or the substrate support) can be from 100 °C to 400 °C. The pressure in the reaction chamber can be from 300 to 1000 Pa.

[0049] During step 104 of providing a silicon-containing precursor to the reaction chamber, precursors for forming a silicon oxide film are continuously introduced into the reaction chamber. Exemplary silicon-containing precursors can include: SiH4, SiF4, Si2H6, TEOS, TMCTS, OMCTS, DMDMOS, 3MS, 4MS, or combinations thereof.

[0050] During step 106, an oxidizing gas can be continuously supplied to the reaction chamber. The oxidizing gas can flow into the reaction chamber simultaneously with or overlapping in time with the step of supplying one or more precursors to the reaction chamber. Exemplary oxidizing gases can include one or more of the following: O2, O3, N2O, N2O4, NxOy, CO, CO2, H2O, or combinations thereof.

[0051] During the step of providing plasma power to the silicon-containing precursor and the oxidizing gas in the reaction chamber (step 108), a direct plasma system can be used to generate plasma, which will be described in more detail below. The power used to generate plasma during step 108 can be between about 200 W and about 2000 W. Using a dual RF power source (such as LRF 400 kHz and HRF 13.56 MHz), the frequency of the power can be in the range from 200 kHz to 30 MHz.

[0052] Figure 2 A timing diagram according to an exemplary embodiment of the present disclosure is shown. Plasma power can be provided during the period of precursor supply and oxidation.

[0053] During step 121, an etching gas can be supplied to the reaction chamber. The etching gas can include a fluorine-containing gas. The fluorine-containing gas can include at least one of the following: NF3, C2F6, CF4, or combinations thereof. The deposition step 102 and the etching step 121 can be repeated until the silicon oxide film fills the gap. The pressure in the reaction chamber during the etching step can be higher than the pressure during the deposition process.

[0054] Figure 3a A scanning electron microscope image of the structure after the deposition step by the PECVD process is shown. The gap after the deposition step is narrow. Therefore, an etching step is required to widen the gap. Figure 3b A scanning electron microscope image of the structure after the direct plasma etching step is shown. Even after the direct plasma, the gap may still be narrow. Figure 3cA scanning electron microscope image of a structure according to an exemplary embodiment of the present disclosure is shown. By using remote plasma etching, the gap is widened. Thus, gap filling can be achieved by repeating the deposition step and such remote plasma-based etching processes.

[0055] Figure 4 A graph illustrating the process conditions of the etching step is shown. After the deposition step, the edge profile of the deposited film may be high. Increasing the amount of NF3 (e.g., between 3 and 5 slm), increasing the pressure (e.g., between 700 Pa and 900 Pa), and decreasing the gap between the susceptor and the showerhead (e.g., between 5 mm and 7 mm) are effective for obtaining a high edge etching rate during the etching step, thereby improving the film uniformity.

[0056] Figure 5 A plasma reactor system 500 according to an exemplary embodiment of the present disclosure is shown. The plasma reactor system 500 can be used to perform one or more steps or sub-steps described herein, and / or to form one or more structures or portions thereof described herein.

[0057] The plasma reactor system 200 may include a pair of conductive flat plate electrodes 4 and 2 that are parallel and face each other inside the reaction chamber 3 (reaction zone). By applying, for example, HRF power (e.g., 13.56 MHz or 27 MHz) and LRF power (e.g., 400 to 500 kHz) from a power source 25 to one electrode (e.g., electrode 4) and electrically grounding the other electrode (e.g., electrode 2), plasma can be excited inside the reaction chamber 3. A temperature regulator may be provided in the lower platform 2 (lower electrode), and the temperature of the substrate 1 placed thereon can be maintained at a desired temperature. The electrode 4 can be used as a gas distribution device, such as a showerhead. Reactant gas, dilution gas (if any), precursor gas, etc. can be introduced into the reaction chamber 3 through the showerhead 4 using one or more of the gas lines 20, gas line 21, and gas line 22, respectively. Although three gas lines are shown, the reactor system 200 may include any suitable number of gas lines. The remote plasma unit 30 can be fluidly coupled to the reaction chamber 3. An etching gas can be introduced into the remote plasma unit 30. The etching gas can be activated by the remote plasma unit 30 and introduced into the reaction chamber 3 through the showerhead 4.

[0058] In reaction chamber 3, a circular conduit 13 with an exhaust pipeline 7 can be provided through which the gas in the interior 11 of reaction chamber 3 can be exhausted. Additionally, a transfer chamber 5 provided below reaction chamber 3 can be provided with a seal gas pipeline 24 to introduce seal gas into the interior 11 of reaction chamber 3 via the interior 16 (transfer zone) of transfer chamber 5, where a partition plate 14 for separating the reaction zone and the transfer zone can be provided (a gate valve for transferring wafers into or out of transfer chamber 5 is omitted in this figure). The transfer chamber can also be provided with an exhaust pipeline 6. In some embodiments, the deposition and etching steps can be carried out in the same reaction space such that the two steps can be carried out continuously without exposing the substrate to air or other oxygen-containing atmospheres.

[0059] Those skilled in the art will understand that the apparatus includes one or more controllers that are programmed or otherwise configured to perform one or more of the method steps described herein. The controller communicates with various power supplies, heating systems, pumps, robots, and gas flow controllers or valves of the reactor, as will be understood by those skilled in the art.

[0060] In some embodiments, a multi-chamber reactor (two or more parts or compartments for processing wafers that are disposed close to each other) can be used, where reactant gases and rare gases can be supplied through shared pipelines, while precursor gases can be supplied through non-shared pipelines.

[0061] The above-described exemplary embodiments do not limit the scope of the present invention, as these embodiments are merely examples of embodiments of the present invention. Any equivalent embodiments are within the scope of the present invention. Indeed, various modifications of the present disclosure, such as alternative useful combinations of the described elements, will become apparent to those skilled in the art from the description. Such modifications and embodiments are also intended to fall within the scope of the appended claims.

Claims

1. A method for forming a silicon oxide film on a substrate; The method comprises the following steps: (a) placing a substrate on a susceptor in a reaction chamber; wherein the substrate includes a gap; (b) a deposition step, comprising: providing a continuous flow of a silicon-containing precursor to a reaction chamber; providing a continuous flow of oxidizing gas to the reaction chamber; and depositing a portion of a silicon oxide film on a substrate by providing plasma power to a silicon-containing precursor and an oxidizing gas; and (c) an etching step, comprising: etching a portion of the portion by supplying an etching gas to the reaction chamber; Wherein the etching gas is activated by a remote plasma unit, and wherein the remote plasma unit is fluidly coupled to the reaction chamber.

2. The method according to claim 1, further comprising repeating step (b) and step (c) until the silicon oxide film fills the gap.

3. The method according to claim 1, wherein: The silicon-containing precursor includes at least one of the following: SiH4, SiF4, Si2H6, TEOS, TMCTS, OMCTS, DMDMOS, 3MS, 4MS or a combination thereof.

4. The method according to claim 1, wherein: The oxidizing gas includes at least one of the following: O2, O3, N2O, N2O4, NxOy, CO, CO2, H2O, H2O2 or a combination thereof.

5. The method according to claim 1, wherein: The etching gas includes a fluorine-containing gas.

6. The method according to claim 1, wherein: The flow rate of the etching gas is between 0.5 and 5 slm.

7. The method according to claim 5, wherein: The fluorine-containing gas includes at least one of the following: NF3, C2F6, CF4 or a combination thereof.

8. The method according to claim 7, wherein: The fluorine-containing gas includes NF3, and the flow rate of NF3 is between 3 and 5 slm.

9. The method according to claim 1, wherein: Steps (b) and (c) are performed in the same reaction chamber.

10. The method according to claim 1, wherein: Step (c) is performed in the second reaction chamber.

11. The method according to claim 1, wherein: The pressure used in step (b) is lower than the pressure used in step (c).

12. The method according to claim 11, wherein: The pressure used in step (c) is between 700 and 900 Pa.

13. The method according to claim 1, wherein: The precursors and gases are provided to the reaction chamber through a shower plate.

14. The method according to claim 13, wherein: The gap between the shower plate and the susceptor is narrower during step (c) than during step (b).

15. The method according to claim 14, wherein: The distance during step (c) is between 5.0 mm and 7.0 mm.

16. The method according to claim 1, wherein: The width of the gap in the substrate is between 30um and 650um, and the depth of the gap is between 5um and 50um.

17. A substrate processing apparatus for performing the steps of claim 1.

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