Encapsulation method

Abstract

The present invention provides a method of encapsulation, and in particular provides methods and apparatus for depositing a low hydrogen content, hermetic thin encapsulation layer at a temperature below about 300 °C. The method includes pulsing a plasma while exposing a substrate to deposition reactants and post-treating the deposited encapsulation film to densify it and reduce the hydrogen content. The post-treatment method includes periodic exposure to an inert plasma without reactants and exposure to ultraviolet radiation at a substrate temperature below about 300 °C.

Description

[0001] This application is a divisional application of the invention patent application with the application number 201710316752.2, the application date of May 8, 2017, and the invention name of "Packaging Method". Technical Field

[0002] The present invention generally relates to the field of semiconductor processing, and more particularly to a packaging method. Background Art

[0003] The fabrication of semiconductor devices involves the formation of memory stacks, which are typically sensitive to oxidation and moisture and may not be able to withstand high-temperature operations or exposure to energetic species. Therefore, memory stacks are typically encapsulated prior to subsequent processing. However, conventional methods of depositing an encapsulation layer may damage components of the processing chamber or the substrate material. Additionally, conventional techniques may not be able to form a sufficiently thin and sealed layer. Summary of the Invention

[0004] Methods and apparatuses for forming an encapsulation layer on a memory device are provided herein. One aspect relates to a method of encapsulating a memory device on a substrate, the method comprising: (i) exposing a substrate having a memory device to a deposition precursor and a reactant at a substrate temperature below 300 °C; and (ii) igniting a plasma to deposit an encapsulation layer on the memory device, the encapsulation layer being sealed and having a hydrogen content of less than 15%.

[0005] In various embodiments, the method further comprises exposing the encapsulation layer to a post-processing process at a temperature below 300 °C.

[0006] For example, in some embodiments, the post-processing process comprises exposing the substrate to a post-processing gas and igniting a second plasma in the absence of a reactant. The substrate may be exposed to the post-processing gas and the second plasma for a duration between about 10 seconds and about 50 seconds. In some embodiments, the post-processing gas is any one of nitrogen, ammonia, helium, argon, and combinations thereof. The method may further comprise repeating (i) and (ii) to form the encapsulation layer.

[0007] In another example, in some embodiments, the post-processing process comprises exposing the substrate to ultraviolet radiation. The ultraviolet radiation may be emitted at a wavelength between about 180 nm and about 600 nm for a duration between about 60 seconds and about 600 seconds.

[0008] In various embodiments, the deposited encapsulation layer is any one of silicon nitride, undoped silicon carbide, oxygen-doped silicon carbide, germanium nitride, undoped germanium carbide, and oxygen-doped germanium carbide.

[0009] In various embodiments, the method includes pulsing a plasma to deposit a capping layer. The pulse of the plasma can have a pulse duration between about 0.02 milliseconds and about 5 milliseconds. The plasma can be pulsed at a pulse frequency between about 100 Hz and about 6 Hz. In some embodiments, the plasma is generated in-situ. In some embodiments, the deposition precursor is a silicon-containing precursor or a germanium-containing precursor.

[0010] In various embodiments, the capping layer is deposited by remote plasma enhanced chemical vapor deposition. For example, in some embodiments, the plasma is generated in a region upstream of and separated from a processing region in which a substrate is housed. In some embodiments, remote plasma enhanced chemical vapor deposition includes: (a) flowing reactants to a remote plasma generation region and igniting the plasma to generate reactant radicals; (b) introducing the reactant radicals into the substrate through a showerhead; and (c) directing a deposition precursor downstream of the showerhead to the substrate while introducing the reactant radicals. The substrate can be processed in a chamber having a chamber pressure between about 1.5 Torr and about 7 Torr.

[0011] In various embodiments, the memory device is a magnetoresistive random access memory. In various embodiments, the memory device includes a magnetic tunnel junction.

[0012] The capping layer can be deposited to a thickness between about 50 angstroms and about 500 angstroms. In some embodiments in which a post-treatment process is used, the post-treatment process can be performed after the capping layer is deposited to a thickness between about 20 angstroms and about 50 angstroms.

[0013] In various embodiments, the capping layer is deposited by plasma enhanced chemical vapor deposition. The capping layer deposited on the memory device can have a step coverage between about 70% and about 90%. In various embodiments, the substrate is patterned with features having an aspect ratio between about 1.5:1 and about 20:1.

[0014] The capping layer can be a silicon nitride film deposited by exposing the substrate to a silicon-containing precursor and a nitrogen-containing reactant. In some embodiments, the capping layer is a silicon carbide film deposited by exposing the substrate to a precursor containing silicon and carbon and hydrogen.

[0015] The method can further include heating the substrate to a temperature of about 300 °C before depositing the capping layer.

[0016] On the other hand, it relates to a method of encapsulating a memory device on a substrate, the method comprising (i) exposing the substrate to a deposition precursor and a reactant at a substrate temperature below about 300 °C; and (b) pulsing the plasma at a pulse frequency between about 100 Hz and about 6 Hz for a duration of about 0.02 milliseconds to about 5 milliseconds while the substrate is exposed to the deposition reactant to form an encapsulation layer such that the formed encapsulation layer is any one of silicon nitride, undoped silicon carbide, oxygen-doped silicon carbide, germanium nitride, undoped germanium carbide, and oxygen-doped germanium carbide.

[0017] The method may further comprise, after depositing the film, exposing the film to a post-treatment process at a substrate temperature below about 300 °C to form an encapsulation layer. The post-treatment process may comprise exposing the substrate to a post-treatment gas and igniting the plasma in the absence of a silicon- or germanium-containing reactant. In some embodiments, the post-treatment process comprises exposing the substrate to ultraviolet radiation.

[0018] On the other hand, it relates to a memory device, the memory device comprising: a memory stack; an airtight encapsulation layer deposited on the memory stack and encapsulating the memory stack, the encapsulation layer being deposited at a substrate temperature below about 300 °C by exposure to a deposition precursor, a reactant, and a plasma, the encapsulation layer having a hydrogen content of less than 15%. In various embodiments, the encapsulation layer has a step coverage of at least 70%. In some embodiments, the exposure may comprise pulsing the plasma with a plasma pulse duration between about 0.02 milliseconds and about 5 milliseconds. The encapsulation layer may be post-treated using UV exposure at a substrate temperature below about 300 °C. In some embodiments, the encapsulation layer is post-treated by exposure to a second plasma for a duration between about 10 seconds and about 50 seconds in the presence of a post-treatment gas.

[0019] In some embodiments, the encapsulation layer is any one of silicon nitride (SiN), silicon carbide (SiC), oxygen-doped silicon carbide (SiCO), germanium nitride (GeN), germanium carbide (GeC), and oxygen-doped germanium carbide (GeCO).

[0020] Remote plasma chemical vapor deposition may be used to deposit the encapsulation layer.

[0021] On the other hand, it relates to an apparatus for processing a semiconductor substrate including a semiconductor material, the apparatus comprising: one or more processing chambers, wherein at least one processing chamber includes a heating pedestal for heating the semiconductor substrate; a plasma generator; one or more gas inlets leading to the processing chamber and associated flow control hardware; and a controller having at least one processor and a memory, wherein the at least one processor and the memory are communicatively connected to each other, the at least one processor is at least operably connected to the flow control hardware, and the memory stores computer-executable instructions for controlling the at least one processor to at least control the flow control hardware by performing the following operations: (i) setting the pedestal temperature to a temperature below about 300 °C; (ii) introducing a deposition precursor and a reactant into the one or more processing chambers; and (iii) when the deposition precursor and the reactant are introduced into the one or more processing chambers, igniting the plasma in a pulsed manner to form a hermetic sealing layer having a hydrogen content of less than 15%.

[0022] The computer-executable instructions may include pulsing the plasma in (iii) at a pulse frequency between about 100 Hz and about 6 Hz for a pulse duration between about 0.02 milliseconds and about 5 milliseconds. In some embodiments, the memory further stores computer-executable instructions for controlling the at least one processor to at least control the flow control hardware by performing the following operations: (iv) after igniting the plasma in a pulsed manner, stopping the inflow of the deposition precursor and the reactant into the one or more processing chambers; (v) introducing an inert gas into the one or more processing chambers; and (vi) igniting the plasma for a duration between about 10 seconds and about 50 seconds.

[0023] In some embodiments, the apparatus further includes an ultraviolet radiation source, wherein the memory further stores computer-executable instructions for controlling the at least one processor to at least control the flow control hardware by turning on the ultraviolet radiation source.

[0024] Specifically, some aspects of the present invention can be described as follows:

[0025] 1. A method of encapsulating a memory device on a substrate, the method comprising:

[0026] (i) exposing the substrate having the memory device to a deposition precursor and a reactant at a substrate temperature below 300 °C; and

[0027] (ii) igniting a plasma to deposit an encapsulation layer on the memory device, the encapsulation layer being hermetic and having a hydrogen content of less than 15%.

[0028] 2. The method according to clause 1, further comprising exposing the encapsulation layer to a post-treatment process at a temperature below 300 °C.

[0029] 3. The method according to clause 1, wherein the encapsulation layer is selected from silicon nitride, undoped silicon carbide, oxygen-doped silicon carbide, germanium nitride, undoped germanium carbide, and oxygen-doped germanium carbide.

[0030] 4. The method according to clause 1, further comprising pulsing the plasma to deposit the encapsulation layer.

[0031] 5. The method according to clause 4, wherein the pulse of the plasma has a pulse duration between about 0.02 milliseconds and about 5 milliseconds.

[0032] 6. The method according to clause 4, wherein the plasma is pulsed at a pulse frequency between about 100 Hz and about 6 Hz.

[0033] 7. The method according to clause 1, wherein the encapsulation layer is deposited by remote plasma enhanced chemical vapor deposition.

[0034] 8. The method as in clause 7, wherein the remote plasma enhanced chemical vapor deposition comprises:

[0035] (a) flowing the reactants to a remote plasma generation region and igniting a plasma to generate reactant radicals;

[0036] (b) introducing the reactant radicals into the substrate through a showerhead; and

[0037] (c) introducing the deposition precursor downstream of the showerhead into the substrate when introducing the reactant radicals.

[0038] 9. The method according to clause 2, wherein the post-treatment process comprises exposing the substrate to a post-treatment gas and igniting a second plasma in the absence of reactants.

[0039] 10. The method according to clause 9, wherein the substrate is exposed to the post-treatment gas and the second plasma for a duration between about 10 seconds and about 50 seconds.

[0040] 11. The method according to clause 9, wherein the post-treatment gas is selected from nitrogen, ammonia, helium, argon, and combinations thereof.

[0041] 12. The method according to clause 2, wherein the post-treatment process comprises exposing the substrate to ultraviolet radiation.

[0042] 13. The method according to any one of clauses 1-12, wherein the memory device is a magnetoresistive random access memory.

[0043] 14. The method according to any one of clauses 1 - 12, wherein the memory device includes a magnetic tunnel junction.

[0044] 15. The method according to any one of clauses 1 - 12, wherein the encapsulation layer is deposited to a thickness between about 50 angstroms and about 500 angstroms.

[0045] 16. The method according to any one of clauses 1 - 12, wherein the encapsulation layer is deposited by plasma enhanced chemical vapor deposition.

[0046] 17. The method according to any one of clauses 1 - 12, wherein the encapsulation layer deposited on the memory device has a step coverage between about 70% and about 90%.

[0047] 18. The method according to any one of clauses 1 - 12, wherein the encapsulation layer is a silicon nitride film deposited by exposing the substrate to a silicon - containing precursor and a nitrogen - containing reactant.

[0048] 19. The method according to any one of clauses 1 - 12, wherein the encapsulation layer is a silicon carbide film deposited by exposing the substrate to a silicon - and carbon - containing precursor and hydrogen.

[0049] 20. The method according to any one of clauses 1 - 12, further comprising heating the substrate to a temperature of about 300 °C before depositing the encapsulation layer.

[0050] 21. A method of encapsulating a memory device on a substrate, the method comprising:

[0051] (i) exposing the substrate to deposition precursors and reactants at a substrate temperature below about 300 °C; and

[0052] (b) pulsing the plasma at a pulse frequency between about 100 Hz and about 6 Hz for a duration between about 0.02 milliseconds and about 5 milliseconds while the substrate is exposed to the deposition reactants to form an encapsulation layer,

[0053] wherein the formed encapsulation layer is selected from silicon nitride, undoped silicon carbide, oxygen - doped silicon carbide, germanium nitride, undoped germanium carbide, and oxygen - doped germanium carbide.

[0054] 22. The method according to clause 21, further comprising exposing the film to a post - treatment process at a substrate temperature below about 300 °C after depositing the film to form the encapsulation layer.

[0055] 23. The method according to clause 22, wherein the post - treatment process includes exposing the substrate to a post - treatment gas and igniting the plasma in the absence of silicon - or germanium - containing reactants.

[0056] 24. The method according to clause 22, wherein the post-treatment process includes exposing the substrate to ultraviolet radiation.

[0057] 25. A memory device, comprising:

[0058] A memory stack;

[0059] An airtight encapsulation layer deposited on the memory stack and encapsulating the memory stack, the encapsulation layer being deposited at a substrate temperature below about 300 °C by exposure to deposition precursors, reactants, and plasma, the encapsulation layer having a hydrogen content of less than 15%.

[0060] 26. The memory device according to clause 25, wherein the encapsulation layer has a step coverage of at least 70%.

[0061] 27. The memory device according to clause 25, wherein the encapsulation layer is selected from silicon nitride (SiN), silicon carbide (SiC), oxygen-doped silicon carbide (SiCO), germanium nitride (GeN), germanium carbide (GeC), and oxygen-doped germanium carbide (GeCO).

[0062] 28. The memory device according to any one of clauses 25-27, wherein the exposure to the deposition precursor includes pulsing the plasma with a plasma pulse duration between about 0.02 milliseconds and about 5 milliseconds.

[0063] 29. The memory device according to any one of clauses 25-27, wherein the encapsulation layer is post-treated using UV exposure at a substrate temperature below about 300 °C.

[0064] 30. The memory device according to any one of clauses 25-27, wherein the encapsulation layer is post-treated by exposure to a second plasma for a duration between about 10 seconds and about 50 seconds in the presence of a post-treatment gas.

[0065] 31. The memory device according to any one of clauses 25-27, wherein the encapsulation layer is deposited using remote plasma enhanced chemical vapor deposition.

[0066] 32. A device for processing a semiconductor substrate comprising a semiconductor material, the device comprising:

[0067] One or more processing chambers, wherein at least one processing chamber includes a heating pedestal for heating the semiconductor substrate;

[0068] A plasma generator;

[0069] One or more gas inlets leading to the processing chamber and associated flow control hardware; and

[0070] A controller having at least one processor and a memory, wherein the at least one processor and the memory are communicatively connected to each other,

[0071] The at least one processor is at least operably connected to the flow control hardware, and

[0072] The memory stores computer-executable instructions for controlling the at least one processor to control the flow control hardware at least by:

[0073] (i) Setting the susceptor temperature to a temperature below about 300 °C;

[0074] (ii) Introducing deposition precursors and reactants into the one or more processing chambers; and

[0075] (iii) When introducing the deposition precursors and the reactants into the one or more processing chambers, igniting the plasma in a pulsed manner to form a hermetic encapsulation layer with a hydrogen content of less than 15%.

[0076] 33. The apparatus according to clause 32, wherein the computer-executable instructions include pulsing the plasma in (iii) at a pulse frequency between about 100 Hz and about 6 Hz with a pulse duration between about 0.02 milliseconds and about 5 milliseconds.

[0077] 34. The apparatus according to clause 32, wherein the memory further stores computer-executable instructions for controlling the at least one processor to control the flow control hardware at least by:

[0078] (iv) After igniting the plasma in a pulsed manner, stopping the flow of the deposition precursors and the reactants to the one or more processing chambers;

[0079] (v) Introducing an inert gas into the one or more processing chambers; and

[0080] (vi) Igniting the plasma for a duration between about 10 seconds and about 50 seconds.

[0081] 35. The apparatus according to clause 32, further comprising an ultraviolet radiation source, wherein the memory further stores computer-executable instructions for controlling the at least one processor to control the flow control hardware at least by turning on the ultraviolet radiation source.

[0082] These and other aspects are further described with reference to the accompanying drawings. Description of the Drawings

[0083] Figure 1 is a schematic diagram of an exemplary memory stack having an encapsulation layer that has been subjected to moisture and air exposure.

[0084] Figures 2A - 2C is a process flow diagram depicting the operations of a method according to the disclosed embodiments.

[0085] Figure 3 is a timing diagram showing an example of a method according to some disclosed embodiments.

[0086] Figures 4 - 6 is a schematic diagram of an exemplary processing chamber for performing the disclosed embodiments.

[0087] Figure 7 is a schematic diagram of an exemplary processing tool for performing the disclosed embodiments.

[0088] Figure 8 is the Fourier transform infrared spectrum of a film from experimental data.

[0089] Figure 9 is a schematic diagram of a substrate having an encapsulation layer deposited in an experiment according to the disclosed embodiments.

[0090] Figure 10 is the Fourier transform infrared spectrum of a film from experimental data.

[0091] Figure 11 is the Fourier transform infrared spectrum of a film from experimental data.

[0092] Figure 12A and 12B is an image of a substrate having an encapsulation layer deposited in an experiment according to the disclosed embodiments.

[0093] Figure 13A is a graph of the hydrogen content of various encapsulation layers deposited in an experiment.

[0094] Figure 13B is a graph of the wet etch rate of various encapsulation layers deposited in an experiment. Detailed Description

[0095] In the following description, numerous specific details are set forth to provide a thorough understanding of the presented embodiments. The disclosed embodiments may be practiced without some or all of these specific details. In other instances, well-known processing operations have not been described in detail so as not to unnecessarily obscure the disclosed embodiments. While the disclosed embodiments will be described in conjunction with specific embodiments, it should be understood that no limitation to the disclosed embodiments is intended.

[0096] In the present invention, the terms "semiconductor wafer", "wafer", "substrate", "wafer substrate", and "partially fabricated integrated circuit" are used interchangeably. One of ordinary skill in the art will understand that the term "partially fabricated integrated circuit" can refer to a silicon wafer during any stage of the many stages of integrated circuit fabrication thereon. Wafers or substrates used in the semiconductor device industry typically have a diameter of 200 mm, or 300 mm, or 450 mm. Unless otherwise specified, the processing details described herein (e.g., flow rates, power levels, etc.) are related to the processing of a 300 mm diameter substrate, or to a processing chamber configured to process a 300 mm diameter substrate, and can be scaled appropriately for substrates or chambers of other sizes.

[0097] The semiconductor manufacturing process involves fabricating memory stacks that typically include materials sensitive to oxidation and moisture. In addition, the memory stacks can also include materials that cannot withstand high-temperature operation or exposure to energetic species. Thus, the memory stacks are typically encapsulated prior to subsequent processing.

[0098] One example of a memory is a magnetic random access memory (MRAM) that includes multiple thin metal layers or films that can be sequentially etched to form a magnetic tunnel junction stack. A magnetic tunnel junction (MTJ) contains a thin dielectric barrier layer between two magnetic materials. Electrons pass through the barrier via the process of quantum tunneling. This can form the basis of a magnetic-based memory. Figure 1 An example of a substrate 101 with a memory stack is provided, the memory stack having a magnetic tunnel junction that includes a first magnetic layer 105a, a dielectric layer 105b, and a second magnetic layer 105c. A layer 103 is disposed between the first magnetic layer 105a and the substrate 101, and the layer 107 can be a barrier layer. Various suitable chemicals can be used for each of these layers, and each layer can include more than one layer.

[0099] A conformal encapsulation layer 109 covers both stacks. A conventional encapsulation layer 109 can include hydrogen 115, and the hydrogen 115 can diffuse into the magnetic tunnel junction and cause the formation of a nitrogen-containing layer 110. The defective encapsulation layer 109 can also be vulnerable to damage 120 that can form when the material is exposed to moisture, such as water molecules 130.

[0100] Conventional techniques for depositing the encapsulation layer are not sufficient to achieve optimal results. For example, an encapsulation layer deposited using conventional techniques results in a high hydrogen content, which can cause diffusion as described above with respect to Figure 1 that described; low density and gas tightness, which can lead to the peeling or removal of the encapsulation layer and insufficient quality to protect the underlying memory; and low step coverage, e.g., having a step coverage of approximately 30% to approximately 50% for vias having a depth-to-width ratio of 4:1, which can cause partial exposure of the sidewalls of the storage material.

[0101] The deposited film is also conformal. The conformity of the film can be measured by the step coverage. The "step coverage" described herein is calculated by obtaining a percentage by dividing the average thickness of the deposited film on the sidewall by the average thickness of the deposited film on the top of the feature and multiplying it by 100.

[0102] To address some of these problems, techniques for achieving a low hydrogen content in the encapsulation layer have been developed, but such techniques are typically carried out at high temperatures that the memory stack cannot tolerate, resulting in etching or damage to the memory (such as the dielectric layer in a magnetic tunnel junction), leading to a non-uniform memory stack.

[0103] Provided herein are methods and apparatuses for depositing a sealing layer having a low hydrogen content, high density, gas tightness, and high step coverage using techniques carried out at low temperatures below about 300 °C. A variety of disclosed embodiments can be carried out at a pressure between about 0.1 Torr and about 20 Torr. In many embodiments, the disclosed methods can be carried out at a substrate temperature below about 300 °C, such as about 250 °C or about 200 °C, or at a substrate temperature between about 200 °C and about 250 °C. In such embodiments, the susceptor can be set to a temperature below about 300 °C to control the substrate temperature. For example, for MRAM and phase change random access memory (PCRAM) applications, the materials on the substrate may be sensitive to high temperatures.

[0104] The film can be deposited by plasma enhanced chemical vapor deposition (PECVD) and / or remote plasma enhanced chemical vapor deposition (RPCVD). In a variety of embodiments, the film is deposited by exposing the substrate to deposition precursors and reactants while pulsing the plasma with short pulses, such as pulses having a pulse duration between about 0.01 ms and about 5 ms, or between about 0.02 ms and about 5 ms, or between about 0.05 ms and about 5 ms, or between about 0.05 ms and about 1.9 ms, between about 0.5 ms and about 1.9 ms. In a variety of embodiments, the plasma is pulsed using a pulse frequency between about 100 Hz and about 6 Hz.

[0105] Multiple embodiments involve deposition followed by one or more post - processing operations. The post - processing operations include periodic exposure to an inert gas and ignition of a plasma during exposure to the inert gas. For example, in some embodiments, after the encapsulation layer is deposited, the encapsulation layer can be exposed to an argon plasma for a duration between about 10 seconds and about 50 seconds. In multiple embodiments, the encapsulation layer can be deposited by cycling between (1) PECVD deposition including short - pulse plasma and (2) exposure to an inert gas and plasma. Another post - processing operation includes exposing the deposited encapsulation layer to ultraviolet radiation at a substrate temperature below 300 °C.

[0106] The hydrogen content of the films deposited by the disclosed embodiments is about 50% to 70% lower than the hydrogen content of encapsulation layers deposited by conventional techniques (which typically have a hydrogen content between 25% and 35%). In multiple embodiments, the deposited encapsulation film has a hydrogen content between about 10% and 15% atomic percentage (measured by FTIR).

[0107] The methods described herein can be used to deposit an encapsulation layer with any suitable chemical, which can include group - IV element nitrides or carbides, either of which can be doped (e.g., with oxygen) or undoped. In multiple embodiments, the encapsulation layer can be any one of the following chemicals or a combination thereof: silicon nitride (SiN), silicon carbide (SiC), oxygen - doped silicon carbide (SiCO), germanium nitride (GeN), germanium carbide (GeC), and oxygen - doped germanium carbide (GeCO).

[0108] The disclosed embodiments are applicable to depositing an encapsulation layer to a thickness between about 50 angstroms and about 500 angstroms. For example, the encapsulation layer deposited on an MRAM stack can have a thickness between about 150 angstroms and about 300 angstroms. The thickness of another exemplary encapsulation layer deposited on a PCRAM stack can be about 50 angstroms. The disclosed embodiments can achieve a step coverage greater than about 70%, or greater than about 90%, or between about 70% and about 90%.

[0109] Figure 2A A process flow diagram depicting operations that can be performed according to the disclosed embodiments is provided. In operation 201, a substrate including a memory stack is provided. In multiple embodiments, the substrate is provided to a processing chamber. The exemplary processing chamber will be further described below with reference to Figures 4 - 6 Further describe the exemplary processing chamber.

[0110] The substrate can be a silicon wafer (e.g., a 200 mm wafer, a 300 mm wafer, or a 450 mm wafer), including a wafer having one or more layers of material (e.g., dielectric, conductive, or semiconductor material) deposited thereon. Non-limiting examples of underlying layers include dielectric layers and conductive layers, such as silicon oxide, silicon nitride, silicon carbide, metal oxides, metal nitrides, metal carbides, and metal layers. In some embodiments, the substrate includes a stack such as a magnetic tunnel junction. In some embodiments, the substrate includes two or more stacks, each stack including layers such as Figure 1 the layers shown. The spacing between the stacks can be narrow such that the aspect ratio between the stacks can be between about 1:1 and about 60:1, or greater than about 1.5:1, or greater than about 4:1, or between about 1.5:1 and 60:1, or between about 1.5:1 and 40:1, or between about 1.5:1 and 20:1, such as about 5:1. In some embodiments, the space between the stacks can be referred to as a "feature". The stacks can contain non-volatile and ferromagnetic materials, such as Co, Fe, Mn, Ni, Pt, Pd, Ru, and combinations thereof (e.g., CoFe), and can include a dielectric layer, such as a MgO layer between two ferromagnetic layers. Some stack materials can include any of the above ferromagnetic layers in combination with boron, such as CoFeB.

[0111] After operation 201 and before operation 203, the substrate can be subjected to a "temperature soak", whereby the substrate is heated to the processing temperature for performing the various operations on the substrate as described herein. For example, the disclosed method can be performed at a substrate temperature below about 300 °C, such as about 250 °C or about 200 °C, or between about 200 °C and about 250 °C. Thus, in some embodiments, the substrate is exposed to a temperature soak such that the pedestal holding the substrate in the processing chamber is set to a temperature, such as about 250 °C, to heat the substrate to the process temperature and stabilize the temperature prior to processing.

[0112] In operation 203, an encapsulation layer is deposited on the memory stack. In various embodiments, the encapsulation layer is deposited on two or more memory stacks. In many embodiments, the encapsulation layer is deposited as a conformal film.

[0113] The encapsulation layer can be deposited by various methods. Figure 2B and 2C A process flow diagram depicting operations of two exemplary methods for depositing an encapsulation layer according to the disclosed embodiments is provided.

[0114] The operations of Figure 2B can be used to perform Figure 2A operation 203. In Figure 2BIn operation 213a, the substrate can be exposed to deposition precursors and reactants at a low substrate temperature. For example, in various embodiments, when the substrate is heated at a temperature below about 300 °C, a continuous flow of deposition precursors and reactants can flow into the processing chamber containing the substrate.

[0115] Depending on the type of encapsulation layer to be deposited, various reactants can be used to deposit the encapsulation layer. For example, the deposition of a silicon nitride encapsulation layer can be carried out by exposing the substrate to a silicon-containing precursor and a nitrogen-containing reactant. In another example, the deposition of a silicon carbide precursor can be carried out by exposing the substrate to a silicon-containing precursor and a carbon-containing reactant. In another example, the deposition of an oxygen-doped silicon carbide precursor can be carried out by exposing the substrate to a silicon-containing precursor and a reactant containing oxygen and carbon. In another example, the deposition of an oxygen-doped silicon carbide precursor can be carried out by exposing the substrate to a silicon- and carbon-containing precursor and hydrogen. In another example, the deposition of a germanium nitride encapsulation layer can be carried out by exposing the substrate to a germanium-containing precursor and a nitrogen-containing reactant. In another example, the deposition of a germanium carbide precursor can be carried out by exposing the substrate to a germanium-containing precursor and a carbon-containing reactant. In another example, the deposition of an oxygen-doped germanium carbide precursor can be carried out by exposing the substrate to a germanium-containing precursor and a reactant containing oxygen and carbon. In another example, the deposition of an oxygen-doped germanium carbide precursor can be carried out by exposing the substrate to a germanium- and carbon-containing precursor and hydrogen.

[0116] The general silicon-containing precursors used in the methods described herein can have the following structure:

[0117]

[0118] where R 1 , R 2 and R 3 can be the same or different substituents and can include silanes, amines, halides, hydrogen, or organic radicals such as alkylamines, alkoxys, alkyls, alkenyls, alkynyls, and aryls.

[0119] Exemplary silicon-containing precursors include polysilanes (H 3 Si 2 -(SiH 2 ) n →SiH 3 ), where n ≥ 1, such as silane, disilane, trisilane, tetrasilane; and trimethylsilylamine:

[0120]

[0121] In some embodiments, the silicon-containing precursor is an alkoxysilane. Alkoxysilanes that can be used include, but are not limited to, the following:

[0122] H x-Si-(OR) y , where x = 1 - 3, x + y = 4, and R is a substituted or unsubstituted alkyl group; and

[0123] H x (RO) y -Si-Si-(OR) y H x , where x = 1 - 2, x + y = 3, and R is a substituted or unsubstituted alkyl group.

[0124] Examples of silicon-containing precursors include: methylsilane; trimethylsilane (3MS); ethylsilane; tetrasilane; pentasilane; octasilane; heptasilane; hexasilane; cyclotetrasilane; cycloheptasilane; cyclohexasilane; cyclooctasilane; cyclopentasilane; 1,4-dioxo-2,3,5,6-tetrasilacyclohexane; diethoxymethylsilane (DEMS); diethoxysilane (DES); dimethoxymethylsilane; dimethoxysilane (DMOS); methyldiethoxysilane (MDES); methyldimethoxysilane (MDMS); octamethoxydodecasiloxane (OMODDS); tert-butoxydisilane; tetramethylcyclotetrasiloxane (TMCTS); tetraoxymethylcyclotetrasiloxane (TOMCTS); triethoxysilane (TES); triethoxysiloxane (TRIES); and trimethoxysilane (TMS or TriMOS).

[0125] In some embodiments, the silicon-containing precursor can be an aminosilane having hydrogen atoms, such as bis(diethylamino)silane, diisopropylaminosilane, tert-butylaminosilane (BTBAS), or tris(dimethylamino)silane. Aminosilane precursors include, but are not limited to, the following: H x -Si-(NR) y , where x = 1 - 3, x + y = 4, and R is an organic or hydride radical.

[0126] In some embodiments, a halogen-containing silane can be used such that the silane includes at least one hydrogen atom. Such a silane can have the chemical formula SiX a H y . For example, in some embodiments, dichlorosilane (H 2 SiCl 2 ) can be used.

[0127] Exemplary nitrogen-containing reactants include nitrogen gas and ammonia gas.

[0128] Exemplary germanium-containing reactants include any germanium compound that can react to form a germanium nitride, germanium carbide, or oxygen-doped germanium carbide layer. Examples include germane, such as Ge n H n+4 , Ge n H n+6, Ge n H n+8 and Ge n H m , where n is an integer from 1 to 10 and n is an integer different from m. Other germanium-containing compounds can also be used, such as alkylgermanes, alkylgermaniums, aminogermanes, carbagermanes, and haloalkanes.

[0129] Exemplary carbon-containing reactants include tetramethylsilane, trimethylsilane, and bistributylaminosilane. In some embodiments, a silicon carbide or germanium carbide encapsulation layer can be deposited by reacting a silicon-containing and a carbon-containing precursor with hydrogen.

[0130] A doped-oxygen carbide can be deposited by using a co-reactant different from one or more silicon-containing precursors or by using a co-reactant in addition to one or more silicon-containing precursors. Examples of such co-reactants include carbon dioxide (CO 2 ), carbon monoxide (CO), water (H 2 O), methanol (CH 3 OH), oxygen (O 2 ), ozone (O 3 ), nitrogen (N 2 ), nitric oxide (N 2 O), ammonia (NH 3 ), methane (CH 4 ), ethane (C 2 H 6 ), acetylene (C 2 H 2 ), ethylene (C 2 H 4 ), diborane, and combinations thereof.

[0131] In some embodiments, oxygen and / or carbon dioxide are introduced together with the precursor to change the composition of the silicon carbide film by removing carbon from the film or the precursor during deposition. In some embodiments, a reactant containing oxygen and carbon (such as methanol) can be used.

[0132] In various embodiments, hydrogen can be used as a reactant to deposit a doped-oxygen silicon carbide encapsulation layer or a doped-oxygen germanium carbide encapsulation layer.

[0133] In operation 213b, when the precursor and the reactant flow continuously, the in-situ plasma can be ignited and pulsed by turning the plasma on or off. The plasma can be ignited at a plasma frequency of 13.56 MHz. In some embodiments, a dual-frequency radio frequency generator is used to generate the plasma. In some embodiments, a single-frequency radio frequency generator is used to generate the plasma. In various embodiments, the plasma power of the high-frequency plasma is about 400 W (0.1 W / cm 2) and about 5000 W (1.5 W / cm 2 ) and. In various embodiments, the plasma power of the low-frequency plasma is about 400 W (0.1 W / cm 2 ) and about 3000 W (1 W / cm 2 ). The plasma can be pulsed at a pulse frequency between about 2 Hz and about 100 kHz, and the duty cycle ranges from about 1% to about 95%. The duty cycle is defined as the duration during which the plasma is on during a period of duration T. During a given period of time, the duration T includes the duration of the pulse-on time (the duration during which the plasma is in the ON state) and the duration of the plasma-off time (the duration during which the plasma is in the OFF state). The pulse frequency is understood to be 1 / T. For example, for a plasma pulse period T = 100 μs, the frequency is 1 / T = 1 / 100 μs or 10 kHz. The duty cycle or duty factor is the fraction or percentage of the period T during which the plasma is on, such that the duty cycle or duty factor is the pulse-on time divided by T. For example, for a plasma pulse period T = 100, if the pulse-on time is 70 μs (such that the duration during which the plasma is on within the period is 70 μs) and the pulse-off time is 30 μs (such that the duration during which the plasma is off within the period is 30 μs), the duty cycle is 70%. In some embodiments, the shortest RF on-time during the pulse step can be as low as about 5 microseconds. In some embodiments, the shortest RF off-time can be about 5 microseconds. Depending on the duty cycle and frequency, various combinations of RF on / RF off pulses can be made. For example, in some embodiments, the operation can be performed for a duration of about 0.01 milliseconds to about 5 milliseconds, or between about 0.02 milliseconds and about 5 milliseconds, or between about 0.05 milliseconds and about 5 milliseconds, or between about 0.05 milliseconds and about 1.9 milliseconds, between about 0.5 milliseconds and about 1.9 milliseconds. During operation 213b, the plasma can be pulsed hundreds to thousands of times depending on the total plasma duration.

[0134] Without being bound by any particular theory, it is believed that pulsing the plasma results in conditions sufficient to form a conformal encapsulation layer with high step coverage on the substrate. In continuous PECVD plasma deposition, when the plasma is on, ions, radicals, neutrals, and other reactive species are generated in the chamber. The presence of ions causes directionality, such that the film deposited on the sidewalls of the features may not be deposited uniformly and high step coverage may not be achieved.

[0135] In pulsed PECVD as described herein, it is believed that when the plasma is turned off after each pulse, the reactive species recombine in the following order: electron disappearance / recombination, ion recombination, and radical recombination. Since the pulses are very short (e.g., the plasma is turned on for a short time and then off for a longer duration to allow deposition), when the plasma is turned off, the electrons and ions recombine, eliminating the directionality of the ions in the deposited material. The radicals take longer to recombine, so the deposition is mainly driven by radicals rather than ions. Then, the radicals can penetrate deeply into high aspect ratio features (1.5:1 - 20:1, particularly suitable for applications greater than 4:1), and conformal high step coverage films are deposited even at the bottom of the features.

[0136] Figure 2C A second exemplary method of depositing an encapsulation layer according to the disclosed embodiments is provided. Operations in Figure 2C can be used to perform Figure 2A operation 203. Figure 2C It can be carried out in any suitable apparatus for remote plasma chemical vapor deposition (RPCVD). An exemplary apparatus is provided in Figure 6 and is described in further detail below.

[0137] In Figure 2C operation 223a, reactants are introduced into a plasma generation region upstream of a showerhead of a processing chamber that houses a substrate. The reactants are introduced into this region to generate reactant radicals. It should be understood that although the process conditions of operation 223a can be varied to generate most of the reactant radicals, some ions, electrons, and other species may be generated in the plasma. For example, in some embodiments, nitrogen gas, or a mixture of nitrogen and hydrogen, can be delivered to the plasma generation region and ignited to form a plasma mainly containing reactant radicals.

[0138] In various embodiments, the reactants can be any of the nitrogen-containing reactants, carbon-containing reactants, oxygen- and carbon-containing reactants, hydrogen, or combinations thereof, as described above with respect to Figure 2B operation 213a, except for ammonia (NH 3 ) gas, because ammonia may not be as likely to form reactant radicals in a remote plasma. Note that for depositing silicon-containing or germanium-containing films, in this operation, silicon- or germanium-containing precursors may not be the reactants delivered to the plasma generation region.

[0139] Note that, in some embodiments, the plasma generation region can be in a remote plasma generator. For example, in some embodiments, a capacitively coupled plasma generator can be used. Plasma is generated by applying a plasma power between about 0 W and about 500 W at a frequency of 13.56 MHz to the plasma generation region. A power density between about 0.1 W / cm 2 to about 1.5 W / cm 2 can be used to generate the plasma.

[0140] In operation 223b, the reactant radicals generated from the plasma generation region are transferred to the processing chamber containing the substrate through a showerhead.

[0141] In operation 223c, a deposition precursor is introduced to the substrate downstream of the showerhead to react with the reactant radicals and form an encapsulation layer on the substrate. In some embodiments, the deposition precursor is introduced downstream of the plasma generation region. The deposition precursor can be flowed or injected into the processing chamber. In various embodiments, the deposition precursor is delivered to the processing chamber via an inlet separate from the showerhead. The deposition precursor can be any Group-IV-containing precursor, such as the silicon-containing precursor or germanium-containing precursor described above with respect to Figure 2B operation 213a.

[0142] It is believed that the reactant radicals transported from the plasma generation region react with the deposition precursor to form composite radicals, which deposit on the substrate surface as an encapsulation layer. It is further believed that since the plasma species delivered to the chamber mainly contain reactant radicals, as opposed to ions, there is little to no ion-induced damage due to ion bombardment on the substrate surface. The pressure in the processing chamber during deposition can be between about 1.5 Torr and about 7 Torr. In some embodiments, the processing chamber can have a pressure greater than about 7 Torr to deposit a more conformal film.

[0143] Operations 223a - 223c can be performed when the substrate in the processing chamber is heated to a temperature below about 300 °C. For example, the encapsulation layer formed in operation 223c can be formed on the substrate on a pedestal in the processing chamber, where the temperature of the pedestal is set to be below about 300 °C, such as a temperature of about 250 °C.

[0144] Using with respect to Figure 2CThe films deposited by the described encapsulation method can have a high step coverage. For example, for a substrate having features with an aspect ratio of 8:1, a doped oxygen silicon carbide encapsulation layer deposited according to a method such as that described with respect to operations 223a - 223c can have a step coverage greater than about 90%. Such films may also have a reduced hydrogen content, which may be due to the mechanism by which the film is deposited. In various embodiments, such films can have a high quality such that the film is thin but sealed. These films exhibit the same film quality on the sidewalls, such as on regions adjacent to the magnetic tunnel junction, as on the field regions of the substrate.

[0145] Return to Figure 2A , in operation 205, an optional post - processing is performed. In some embodiments, the post - processing methods described herein can be used in conjunction with conventional PECVD of the encapsulation layer to reduce the hydrogen content and improve the quality of the deposited layer. However, encapsulation layers deposited using conventional PECVD and post - processed using the disclosed embodiments may not produce high - quality films with the same high step coverage as those deposited using the disclosed embodiments (as described above with respect to Figure 2B and 2C described) and the post - processing embodiments described herein.

[0146] In some embodiments, the post - processing can be optional, such that a method such as that described with respect to Figure 2B or 2C is used to deposit the encapsulation layer. Encapsulation layers deposited using a combination of the deposition methods described herein and the post - processing methods described in further detail below will exhibit higher - quality, higher - step - coverage films than films deposited without post - processing. Examples are described in further detail herein.

[0147] Operation 205 can be performed by executing a periodic plasma treatment, examples of which are shown in Figure 2A operations 215a and 215b. Alternatively, operation 205 can be performed by executing an ultraviolet (UV) exposure post - processing process depicted in Figure 2A operation 225. In some embodiments, the substrate can be subjected to one or a combination of the two post - processing methods. For example, in some embodiments, after depositing the encapsulation layer, the substrate can be exposed to a periodic plasma treatment. In some embodiments, the operation can be repeated on a substrate including a first encapsulation layer exposed to a periodic plasma treatment such that after the periodic plasma treatment, a second encapsulation layer can be deposited on the treated first encapsulation layer. In some embodiments, after depositing the encapsulation layer, the substrate can be exposed to UV for UV post - processing. In some embodiments, after depositing the encapsulation layer, the substrate can be exposed to a periodic plasma treatment followed by a UV post - processing.

[0148] In operation 215a, as a method of performing a post - processing process, a substrate including a deposited encapsulation layer is exposed to a plasma without silicon - containing or germanium - containing reactants at a substrate temperature below about 300 °C to process the deposited encapsulation layer. In some embodiments in which the post - processing process is used, the post - processing process may be performed after the encapsulation layer is deposited to a thickness between about 20 angstroms and about 50 angstroms. In some embodiments, pulsed plasma deposition as described above with respect to Figure 2B is performed in combination with operation 215a such that operation 215a is performed periodically. For example, in some embodiments, after performing the operation 203 in Figure 2A , and thus after performing the operations 213a and 213b in Figure 2B , the flow of silicon - containing precursors and reactants is stopped, a post - processing gas is introduced, and a continuous plasma is ignited to process the deposited film in the absence of silicon - containing or germanium - containing reactants. Compared to performing pulsed PECVD alone, performing a combination of pulsed PECVD and post - processing plasma exposure to the post - processing plasma results in a higher - quality, higher step - coverage, and lower - hydrogen - content silicon - containing film. Although conventionally deposited PECVD films using continuous plasma deposition can be used in combination with post - processing, such films may not produce high - quality films with as high a step - coverage as the films deposited using the combination of pulsed PECVD and post - processing. In various embodiments in which the encapsulation layer is deposited by the pulsed PECVD process as described above with reference to Figure 2B , the plasma exposure during operation 215a can be longer than the time of each plasma pulse of the operation 213b in Figure 2B . For example, in various embodiments, the plasma exposure during operation 215b can have a duration between about 10 seconds and about 50 seconds, while each plasma pulse used to deposit the encapsulation layer in operation 203 during the pulse of operation 213b, for example, can have a short duration, from one - hundredth of a millisecond to a few milliseconds. Exemplary pulse durations for plasma pulsing in operation 213b are described above with reference to Figure 2B .

[0149] In addition, different from operation 213b, during operation 215a, a reaction stream without silicon or germanium is made to flow into the processing chamber. Instead, during operation 215, when the plasma is ignited, a post-treatment gas such as an inert gas is made to flow into the processing chamber, thereby generating a plasma species capable of altering and densifying the deposited encapsulation layer. The inert gas can be selected according to the type of film to be deposited and the reactants used during the encapsulation layer deposition process. A general list of possible inert gases includes nitrogen, ammonia, and inert gases such as helium and argon. The gas can be selected according to the type of film to be deposited and the reactants used during the deposition process. The post-treatment gas can include nitrogen only, ammonia only, a nitrogen / ammonia mixture, argon only, helium only, an argon / helium mixture, and combinations thereof. Other inert gases can also be used. In some embodiments, even if nitrogen is used to form silicon nitride in operation 205, operation 207 can involve exposure to a nitrogen plasma during post-treatment to reduce the hydrogen content and densify the film. It is believed that periodic exposure to a plasma and an inert gas for a longer duration reduces the hydrogen content of the deposited encapsulation layer. The upper region of the encapsulation layer can have a reduced hydrogen content. For example, in some embodiments, the top about 25 angstroms to about 30 angstroms of the encapsulation layer can have a reduced hydrogen content.

[0150] In operation 215b, operations 203 - 215a can be optionally repeated such that the encapsulation layer is deposited in different cycles, each cycle including deposition and post-treatment. The repeated cycles can be performed to improve the quality of the deposited encapsulation layer.

[0151] In operation 225, the substrate can be exposed to UV radiation at a substrate temperature below about 300 °C. For operation 225, the substrate can be transferred from the deposition processing chamber to the UV radiation processing chamber. Referring below Figure 5 to describe an exemplary device. Ultraviolet radiation can be emitted at a wavelength between about 180 nm and about 600 nm for a duration between about 60 seconds and about 600 seconds.

[0152] In some embodiments, operation 225 can be performed at a temperature higher than the substrate temperature used during the encapsulation layer deposition. In some embodiments, if a conventional PECVD encapsulation layer is deposited at a temperature higher than 300 °C, the encapsulation layer can have less hydrogen content than the encapsulation layer deposited at a temperature below 300 °C, but the encapsulation layer deposited at a temperature higher than 300 °C may be less susceptible to changes caused by UV treatment, so UV treatment may not help reduce the overall hydrogen content of such an encapsulation layer. Therefore, UV treatment is suitable for embodiments in which the encapsulation layer is deposited at a temperature below about 300 °C.

[0153] In some embodiments, the substrate temperature during deposition can be different from the substrate temperature during UV treatment. In some embodiments where periodic plasma treatment is also used between deposition and UV treatment, the substrate temperature during periodic plasma treatment can be the same as or different from the substrate temperature during deposition. In various embodiments, although the substrate temperatures are different, the substrate temperature during each operation can be below about 300 °C. The temperatures selected for deposition and UV treatment can depend on the encapsulation layer material to be deposited. For example, a germanium-containing encapsulation layer includes germanium-hydrogen bonds, which have an energy lower than that of silicon-hydrogen bonds. Thus, for the deposition and treatment of a germanium-containing encapsulation layer, deposition can be carried out at a higher temperature (e.g., at about 300 °C), and treatment with UV radiation can be carried out at the same higher temperature because the bond energy between germanium and hydrogen in the germanium-containing encapsulation layer (although the layer is deposited at a higher temperature to produce a layer with less hydrogen content than a layer deposited at a lower temperature) is less than the bond energy between silicon and hydrogen. Therefore, UV radiation can change the germanium-hydrogen bonds in the film deposited at a higher temperature, while UV radiation may not be able to change the silicon-hydrogen bonds in the film deposited at the same temperature. Thus, in some embodiments, to deposit a silicon-containing encapsulation layer, the silicon-containing encapsulation layer can be deposited at a lower deposition temperature (e.g., a temperature below about 250 °C), and then UV radiation can be carried out at a temperature of, for example, about 300 °C.

[0154] In one example, an encapsulation layer can be deposited by the method described above with respect to Figure 2B and then UV treatment can be carried out at a temperature below about 300 °C (e.g., about 300 °C, or about 250 °C). In another example, an encapsulation layer can be deposited by the method described above with respect to Figure 2C and then UV treatment can be carried out at a temperature below about 300 °C. In another example, an encapsulation layer can be deposited by the method described above with respect to Figure 2B and then post-treatment as described with respect to operations 215a and 215b can be carried out, and then UV treatment can be carried out at a temperature below about 300 °C. In another example, an encapsulation layer can be deposited by the method described above with respect to Figure 2C and then post-treatment as described with respect to operations 215a and 215b can be carried out, and then UV treatment can be carried out at a temperature below about 300 °C.

[0155] Figure 3 is an exemplary timing diagram showing an example of a method according to certain disclosed embodiments. Method 300 includes a deposition stage 303, a periodic plasma post-treatment stage 315, and a UV treatment stage 325. The deposition stage 303 can correspond to Figure 2A operation 203. In this exemplary process 300, the deposition stage 303 includes using as described above with respect to Figure 2BThe pulse PECVD-deposited encapsulation layer. An exemplary process 300 is provided when depositing a silicon-containing encapsulation layer. As shown, an inert gas may be flowed during deposition stage 303. A silicon-containing precursor is also flowed constantly during deposition stage 303, and the second reactant may be any of the reactants described above with respect to Figure 2B operation 213a, which may also be flowed constantly during deposition stage 303. As shown in deposition stage 303, the plasma may be pulsed such that the plasma is turned on and off in short pulses. During this stage, UV exposure is not used.

[0156] In the periodic plasma post-treatment stage 315, the inert gas may continue to flow. Note that although the inert gas used in method 300 is used as a post-treatment gas for post-treatment to ignite the plasma, in some embodiments, the periodic plasma post-treatment may be performed using a post-treatment gas (which is not an inert gas and / or not a carrier gas for delivering process gases). For example, any suitable post-treatment gas as described above with respect to Figure 2A may be used to generate the plasma for post-treatment. The periodic plasma post-treatment stage 315 may correspond to Figure 2A operations 215a and 215b. During this stage, the silicon-containing precursor flow and the second reactant flow are turned off to prevent any material from depositing on the substrate. For example, as Figure 3 shown, the plasma is turned on and off for two cycles. Note that the duration of plasma turn-on during each exposure in the periodic plasma post-treatment stage is longer than the short pulses used during deposition. Note that although two cycles are described here, in some embodiments, the periodic plasma post-treatment may perform one cycle, or may perform two or more cycles. Although the UV treatment stage 325 immediately follows the periodic plasma post-treatment stage 315 in this embodiment, in some embodiments, another deposition stage may be performed after the periodic plasma post-treatment stage 315. During the periodic plasma post-treatment stage 315, there is no UV exposure.

[0157] In the UV treatment stage 325, the inert gas may be turned off, and all reactant flows including the silicon-containing precursor and the second reactant flow are cut off. Here, the plasma is not ignited, and only the UV radiation is turned on to modify, densify, and / or cure the deposited encapsulation layer. The UV treatment stage 325 may correspond to Figure 2A operation 225.

[0158] Device

[0159] The deposition techniques provided herein can be implemented in a plasma enhanced chemical vapor deposition (PECVD) chamber or a conformal film deposition (CFD) chamber, or in some embodiments, in an atomic layer deposition (ALD) chamber. Such chambers can take a variety of forms and can be part of an apparatus that includes one or more chambers or reactors (sometimes including multiple stations), one or more of which, for example, as described in further detail with respect to Figure 7 which can each accommodate one or more substrates or wafers and can be configured to perform various substrate processing operations. One or more chambers can hold the substrate at defined one or more positions (with or without movement within the position, such as rotation, vibration, or other agitation). In one embodiment, during the process, the substrate undergoing film deposition can be transferred from one station within the chamber to another station (or from one chamber within the apparatus to another chamber). In other embodiments, the substrate can be transferred from a chamber within the apparatus to a chamber to perform different operations, such as a UV exposure operation, an etching operation, or a lithography operation. The complete film deposition can be performed entirely at a single station, or any portion of the total film thickness can be deposited for any deposition step. When being processed, each substrate can be held in place by a pedestal, a substrate chuck, and / or other substrate holding means. For certain operations in which the substrate is to be heated, the apparatus can include a heater, such as a hot plate.

[0160] Figure 4A simple block diagram depicting various reactor components arranged to implement the methods described herein is provided. Reactor 400 can be used to deposit an encapsulation layer as described herein. As shown, reactor 400 includes a processing chamber 424 that surrounds other components of the reactor and is configured to contain plasma generated by a capacitively coupled system including a showerhead 414 that works with a grounded heater block 420. A high-frequency (HF) radio frequency (RF) generator 404 and a low-frequency (LF) RF generator 402 can be connected to a matching network 406 and the showerhead 414. The power and frequency provided by the matching network 406 can be sufficient to generate plasma from the process gases supplied to the processing chamber 424. For example, the matching network 406 can provide power in the range of 100 W to 1000 W. The HF RF component can generally be between 1 MHz and 100 MHz, such as 13.56 MHz. In operations where an LF component is present, the LF component can be less than about 1 MHz, such as 100 kHz. In some embodiments, the plasma can be pulsed at a pulse frequency between about 300 Hz and about 1.5 kHz (e.g., for a duty cycle of about 500 Hz). The controller 428 can be configured to set the duration of each plasma pulse to be between about 0.05 milliseconds and about 5 milliseconds, such as a duration between about 0.02 milliseconds and about 1.9 milliseconds. In some embodiments, the plasma can be turned on for periodic plasma processing as a post-treatment as described herein. For periodic plasma processing, the plasma can be turned on for a duration between about 10 seconds and about 50 seconds.

[0161] Within reactor 400, a susceptor 418 can support a substrate 416. The susceptor 418 can include a chuck, forks, or lift pins (not shown) to hold and transfer the substrate 416 during and between deposition and / or post-treatment operations. The chuck can be an electrostatic chuck, a mechanical chuck, or various other types of chucks that can be used in industry and / or research.

[0162] A variety of process gases can be introduced via an inlet 412. For example, the gases can include Group-IV precursors, such as silicon-containing precursors or germanium-containing precursors. The gases can include a second reactant, such as hydrogen, a carbon-containing reactant, an oxygen-containing reactant, an oxygen- and carbon-containing reactant, a nitrogen-containing reactant (e.g., nitrogen or ammonia), and combinations thereof. In some embodiments, an inert gas or a carrier gas can also be flowed. Exemplary inert gases include argon, helium, and in some cases, nitrogen. In some embodiments, the carrier gas is transferred before delivering the process gases to the processing chamber 424.

[0163] Multiple source gas lines 410 are connected to the manifold 408. The gases can be pre-mixed or not pre-mixed. Appropriate valves and mass flow control mechanisms can be employed to ensure the delivery of the correct process gases during the deposition and post-treatment stages of the process. In cases where chemical precursors are delivered in liquid form, liquid flow control mechanisms can be employed. Then, during transport in a manifold heated to a temperature above the evaporation point of the chemical precursor supplied in liquid form, such liquid can be vaporized and mixed with the process gas before reaching the processing chamber 424.

[0164] Process gases, such as silicon-containing precursors or nitrogen-containing gases, can leave the processing chamber 424 via the outlet 422. A vacuum pump 426, such as a single-stage or two-stage mechanical dry pump and / or a turbomolecular pump, can be used to evacuate the process gas from the processing chamber 424 and maintain an appropriate low pressure within the processing chamber 424 by using a flow restricting device with closed-loop control (such as a throttle valve or a flap valve).

[0165] The apparatus 400 includes a controller 428, which can include one or more memory devices, one or more mass storage devices, and one or more processors. The processor can include a CPU or a computer, analog and / or digital input / output connections, a stepper motor controller board, etc. The apparatus 400 includes a system controller 428 for controlling the process state and the hardware state of the processing tool 400. The controller 428 can be configured to deliver certain process gases at various flow rates for certain durations, and control the plasma frequency, plasma pulse frequency, plasma power, and other process conditions as described herein. The controller 428 can be configured to turn on and off the plasma according to some embodiments. The controller 428 can have any of the characteristics of the controller 750 described below Figure 7 described.

[0166] In some embodiments, the encapsulation layer can be deposited in a remote plasma chemical vapor deposition (RPCVD) chamber. Figure 5A simplified view of an apparatus 500 that can be used for certain radical-based processes, such as radical-based encapsulation layer deposition processes, is shown. According to certain embodiments, other radical-based methods and reaction chambers can also be used. The apparatus 500 includes a processing chamber 524 that includes a chamber wall 503, a chamber bottom plate 504, and a chamber top plate 505. Inside the processing chamber 524 is a substrate support 518, and a substrate 516 is located on the substrate support 518. The processing chamber 524 further includes an inlet 508 and an outlet 509. A remote plasma source 510 is disposed above the processing chamber 524. The remote plasma source 510 includes a plasma generator (not shown) for generating a plasma within the remote plasma source. The plasma generator includes hardware (e.g., coils, electrodes, etc.) for generating the plasma, and the plasma can be inductively coupled plasma, capacitively coupled plasma, microwave coupled plasma, etc. The remote plasma source 510 is separated from the processing chamber 524 by a showerhead 514a having a plurality of showerhead holes 514b. The remote plasma source 510 has an inlet 512 for providing a gas for generating the remote plasma. The apparatus 500 includes a system controller 550 for controlling the process state and hardware state of the processing tool 500. The controller 550 can have any of the characteristics of the controller 750 described below with respect to Figure 7 The controller 750 described.

[0167] In various embodiments, the deposited encapsulation layer can be subjected to ultraviolet (UV) post-treatment as described in the disclosed embodiments, such as with respect to operation 225 described above. In some embodiments, a substrate including the deposited encapsulation layer can be transferred into a chamber to cure the substrate or expose the substrate to UV radiation. Figure 2A A schematic diagram of an example of an exposure chamber 624 for exposing a substrate 616 to UV is shown. For example, Figure 6 The apparatus 600 shown can be used to perform as described above with respect to Figure 6 The apparatus 600 shown can be used to perform as described above with respect to Figure 2AThe operation 225 described above. The apparatus 600 has a plasma generation section 611 and an exposure chamber 624 separated by a showerhead assembly or panel 614. Inside the exposure chamber 624, a platen (or stage) 618 provides wafer support. The platen 618 is equipped with heating / cooling elements. In some embodiments, the platen 618 is also configured to apply a bias to the substrate 616. A low pressure is obtained in the exposure chamber 624 via a vacuum pump through a conduit 607. A source of gaseous processing gas provides a gas flow to the plasma generation section 611 of the apparatus 600 through an inlet 612. The plasma generation section 611 may be surrounded by an induction coil (not shown). During operation, a gas mixture is introduced into the plasma generation section 611, the induction coil is energized, and a plasma is generated in the plasma generation section 611. The showerhead assembly 614 may have a voltage applied and terminate the flow of some ions and allow neutral flow species to enter the exposure chamber 624. The apparatus 600 includes a system controller 650 for controlling the process conditions and hardware state of the apparatus 600. The controller 650 may have any of the characteristics of the controller 750 described below with respect to Figure 7 the controller 750 described.

[0168] As described above, the techniques for deposition and post-processing encapsulation discussed herein can be implemented on multi-station or single-station tools. Figure 7 is a schematic diagram of an example of such a tool. In a specific embodiment, a 300 mm Lam Vector TM tool with a 4-station deposition scheme or a 200 mm Sequel TM tool with a 6-station deposition scheme can be used. In some embodiments, a tool for processing 450 mm substrates can be used. In various embodiments, the substrate can be repositioned after each deposition and / or post-deposition plasma treatment, or if the etch chamber or station is also part of the same tool, it can be repositioned after the etch step, or the substrate can be repositioned after multiple depositions and processes at a single station.

[0169] Figure 7FIG. shows a schematic view of an embodiment of a multi-station processing tool 700 having an inlet load lock 702 and an outlet load lock 704, one or both of the inlet load lock 702 and the outlet load lock 704 may include a remote plasma source. A robot 706 is configured at atmospheric pressure to move wafers from a cassette loaded through a pod 708 to the inlet load lock 702 via an atmospheric port 710. The wafer is placed on a pedestal 712 in the inlet load lock 702 by the robot 706, the atmospheric port 710 is closed, and the load lock 702 is pumped. In the case where the inlet load lock 702 includes a remote plasma source, in the inlet load lock 702, the wafer can be exposed to remote plasma processing in the inbound load lock 702 and then introduced into the processing chamber 714. Additionally, the wafer can also be heated in the inlet load lock 702, for example, to remove moisture and adsorbed gases. In some embodiments, the wafer can undergo a "temperature soak" as described elsewhere herein in the inbound load lock 702.

[0170] The chamber transfer port 716 of the processing chamber 714 is opened, and another robot (not shown) places the wafer on the pedestal of the first station shown in the reactor in the reactor for processing. Although Figure 7 the illustrated embodiment includes load locks, it should be understood that in some embodiments, the wafer can enter the processing station directly.

[0171] The depicted processing chamber 714 includes Figure 7 four processing stations numbered from 1 to 4 in the illustrated embodiment. Each station has a heated pedestal (shown as 718 for station 1) and a gas line inlet. It should be understood that in some embodiments, each processing station can have different purposes or multiple purposes. For example, in some embodiments, the processing station can switch between a PECVD deposition mode and a periodic plasma post-treatment process mode. In some embodiments, the processing station can switch between a chemical vapor deposition (CVD) process mode and a plasma-enhanced chemical vapor deposition (PECVD) process mode. In some embodiments, the processing station can switch between a PECVD process mode and an RPCVD process mode. Additionally or alternatively, in some embodiments, the processing chamber 714 can include one or more paired atomic layer deposition or plasma-enhanced atomic layer deposition processing stations. Although the depicted processing chamber 714 includes four stations, it should be understood that the processing chamber according to certain disclosed embodiments can have any suitable number of stations. For example, in some embodiments, the processing chamber can have five or more stations, while in other embodiments, the processing chamber can have three or fewer stations.

[0172] Figure 7Depicts an embodiment of a wafer processing system 790 for transferring wafers within a processing chamber 714. In some embodiments, the wafer handling system 790 can transfer wafers between various processing stations and / or between a processing station and a load lock. It should be understood that any suitable wafer handling system can be employed. Non-limiting examples include wafer conveyors and wafer handling robots. Figure 7 Also depicts an embodiment of a system controller 750 for controlling the process state and hardware state of a processing tool 700. The system controller 750 can include one or more memory devices 756, one or more mass storage devices 754, and one or more processors 752. The one or more processors 752 can include a CPU or computer, analog and / or digital input / output connections, a stepper motor controller board, etc.

[0173] In some embodiments, the system controller 750 controls all activities of the processing tool 700. The system controller 750 executes system control software 758 stored in the mass storage device 754, loaded into the memory device 756, and executed on the processor 752. Alternatively, the control logic can be hard-coded in the controller 750. Application-specific integrated circuits, programmable logic devices (e.g., field-programmable gate arrays or FPGAs), etc. can be used for these purposes. In the following discussion, wherever "software" or "code" is used, functionally comparable hard-coded logic can be used therein. The system control software 758 can include instructions for controlling timing, gas mixtures, gas flow rates, chamber and / or station pressures, chamber and / or station temperatures, wafer temperatures, target power levels, RF power levels, substrate pedestals, chucks, and / or pedestal positions, plasma pulse frequencies, plasma exposure durations, UV radiation durations, and other parameters of a specific process performed by the processing tool 700. The system control software 758 can be configured in any suitable manner. For example, various processing tool component subroutines or control objects can be written to control the operation of the processing tool components necessary to perform various processing tool processes. The system control software 758 can be encoded in any suitable computer-readable programming language.

[0174] In some embodiments, the system control software 758 can include input / output control (IOC) sequencing instructions for controlling the various parameters described above. Other computer software and / or programs stored on the mass storage device 754 and / or the memory device 756 associated with the system controller 750 can be employed in some embodiments. Examples of programs or program segments for this purpose include substrate positioning programs, process gas control programs, pressure control programs, heater control programs, UV exposure control programs, and plasma control programs.

[0175] The substrate positioning program may include instructions for processing tool components that load a substrate onto a pedestal and control the spacing between the substrate and other components of the processing tool.

[0176] The process gas control program may include instructions for controlling gas composition (such as silicon-containing gases, germanium-containing gases, nitrogen-containing gases, carbon-containing gases, oxygen- and carbon-containing gases, carbon-containing gases, post-treatment gases, and other gases described herein) and flow rates, and optionally code for flowing the gas to one or more processing stations prior to deposition to stabilize the pressure in these processing stations. The pressure control program may include code for controlling the pressure within a processing station by adjusting, for example, a throttle valve in the exhaust system of the processing station, the gas flow into the processing station, and the like.

[0177] The heater control program may include code for controlling the current flowing to a heating unit for heating the substrate. Alternatively, the heater control program may control the delivery of a heat transfer gas (such as helium) toward the substrate.

[0178] The plasma control program may include code for setting the RF power level applied to a processing electrode in one or more processing stations in accordance with embodiments herein.

[0179] The UV exposure control program may include code for setting the exposure duration of UV radiation in one or more processing stations in accordance with embodiments herein.

[0180] The pressure control program may include code for maintaining the pressure in the reaction chamber in accordance with embodiments herein.

[0181] In some embodiments, there may be a user interface associated with the system controller 750. The user interface may include a display screen, a graphical software display of the apparatus and / or process conditions, and user input devices such as a pointing device, keyboard, touch screen, microphone, and the like.

[0182] In some embodiments, the parameters adjusted by the system controller 750 relate to process conditions. Non-limiting examples include process gas composition and flow rate, temperature, pressure, plasma conditions (such as RF bias power level), and the like. These parameters may be provided to the user in the form of a recipe, which may be input using the user interface.

[0183] Signals for monitoring processing can be provided by analog and / or digital input connectors of system controller 750 from various processing tool sensors. Signals for controlling processing can be output on the analog and digital output connectors of processing tool 700. Non-limiting examples of processing tool sensors that can be monitored include mass flow controllers, pressure sensors (e.g., pressure gauges), thermocouples, etc. Appropriately programmed feedback and control algorithms can be used with data from these sensors to maintain process conditions.

[0184] System controller 750 can provide program instructions for performing the deposition processes described above. The program instructions can control a variety of processing parameters, such as DC power level, RF power level, pressure, temperature, plasma pulse frequency, plasma exposure duration, UV exposure duration, etc. The instructions can control these parameters to operate the in-situ deposition of the film stack according to the various embodiments described in the present invention.

[0185] System controller 750 will generally include one or more memory devices and one or more processors configured to execute instructions such that the device will perform the methods disclosed herein. A machine-readable medium containing instructions for controlling processing operations according to the disclosed embodiments can be coupled to system controller 750.

[0186] In some embodiments, controller 750 is part of a system, which can be part of the above-described embodiments. Such a system can include semiconductor processing equipment, which includes one or more processing tools, one or more chambers, one or more platforms for processing, and / or specific processing components (wafer pedestal, gas flow system, etc.). These systems can be integrated with electronics to control the operation of these systems before, during, or after the processing of semiconductor wafers or substrates. The electronics can be referred to as a "controller" that can control various components or sub-parts of one or more systems. Depending on the processing requirements and / or the type of system, controller 750 can be programmed to control any of the processes disclosed in the present invention, including controlling the delivery of processing gases, temperature settings (e.g., heating and / or cooling), pressure settings, vacuum settings, power settings, radio frequency (RF) generator settings, RF matching circuit settings, frequency settings, flow rate settings, plasma pulse frequency settings, UV exposure settings, fluid delivery settings, position and operation settings, the loading and unloading of wafers into and out of the tool and other transfer tools and / or the transfer of load locks connected to or interfacing with a particular system.

[0187] Broadly speaking, the controller 750 can be defined as an electronic device with various integrated circuits, logic, memory, and / or software that receives instructions, issues instructions, controls operations, enables cleaning operations, enables endpoint measurements, etc. The integrated circuit can include a chip storing program instructions in the form of firmware, a digital signal processor (DSP), a chip defined as an application specific integrated circuit (ASIC), and / or one or more microprocessors or microcontrollers that execute program instructions (e.g., software). The program instructions can be instructions delivered to the controller or system in the form of various different settings (or program files), and the different settings (or program files) define the operating parameters for specific processing on or for a semiconductor wafer or to the system. In some embodiments, the operating parameters can be part of a recipe defined by a process engineer to complete one or more processing steps in the manufacturing process of one or more layers, materials, metals, oxides, silicon, silicon dioxide, surfaces, circuits, and / or bare chips of a wafer.

[0188] In some embodiments, the controller 750 can be part of a computer that is integrated with, coupled to, or networked to the system or a combination thereof. For example, the controller can be in the "cloud" or be all or part of a fab host system, which can allow remote access to wafer processing. The computer can enable remote access to the system to monitor the current progress of manufacturing operations, check the history of past manufacturing operations, check trends or performance criteria of multiple manufacturing operations, to change the parameters of the current processing, set processing steps to follow the current processing or start a new process. In some examples, a remote computer (e.g., a server) can provide a process recipe to the system via a network, which can include a local network or the Internet. The remote computer can include a user interface that allows input or programming of parameters and / or settings, which are then transmitted from the remote computer to the system. In some examples, the controller 750 receives instructions in the form of data that specify the parameters for each processing step to be performed during one or more operations. It should be understood that these parameters can be for the type of process to be performed as well as the type of tool, and the controller is configured to connect to or control that type of tool. Thus, as described above, the controller 750 can be distributed, for example, by including one or more discrete controllers that are connected together via a network and work towards a common goal (e.g., the processes and controls described herein). An example of a distributed controller for these purposes can be one or more integrated circuits in the chamber that communicate with one or more remote integrated circuits (e.g., at the platform level or as part of a remote computer), which combine to control the processes in the chamber.

[0189] In some embodiments, apparatus configured to perform the techniques described herein may be provided. Suitable apparatus may include hardware for performing various processing operations and a system controller 750 having instructions for controlling the processing operations in accordance with the disclosed embodiments. The system controller 750 will generally include one or more memory devices and one or more processors communicatively coupled to and configured to execute instructions with various process control devices (e.g., valves, RF generators, substrate processing systems, etc.) such that the apparatus will perform the techniques in accordance with the disclosed embodiments, such as, for example, the techniques provided in Figures 2A - 2C the operations of. A machine-readable medium containing instructions for controlling process operations in accordance with the present disclosure may be coupled to the system controller 750. The controller 750 may be communicatively coupled to various hardware devices (e.g., mass flow controllers, valves, RF generators, vacuum pumps, etc.) to facilitate control of the various process parameters associated with the deposition operations described herein.

[0190] In some embodiments, the system controller 750 may control all activities of the reactor 700. The system controller 750 may execute system control software stored in a mass storage device, loaded into a memory device, and executed on a processor. The system control software may include instructions for controlling gas flow timing, substrate movement, RF generator activation, etc., and instructions for controlling other parameters such as gas mixture, chamber and / or station pressure, chamber and / or station temperature, substrate temperature, target power level, RF power level, substrate pedestal, chuck and / or pedestal position, and specific processes performed by the reactor apparatus 700. For example, the software may include instructions or code for controlling the flow rate of silicon-containing precursors, the flow rate of reactants, the flow rate of nitrogen-containing gases, plasma frequency, plasma pulse frequency, plasma power, UV exposure time, precursor and reactant exposure time, the flow rate of post-treatment gases, and the UV exposure time for each of the above flow chemicals. The system control software may be configured in any suitable manner. For example, various processing tool component subroutines or control objects may be written to control the operation of the processing tool components necessary to perform various processing tool processes. The system control software may be encoded in any suitable computer-readable programming language.

[0191] The system controller 750 will generally include one or more memory devices 756 and one or more processors 752 configured to execute instructions such that the apparatus will perform the techniques in accordance with the disclosed embodiments. A machine-readable medium containing instructions for controlling processing operations in accordance with the disclosed embodiments may be coupled to the system controller 750.

[0192] Exemplary systems can include, but are not limited to: plasma etch chambers or modules, deposition chambers or modules, spin rinse chambers or modules, metal plating chambers or modules, cleaning chambers or modules, bevel edge etch chambers or modules, physical vapor deposition (PVD) chambers or modules, chemical vapor deposition (CVD) chambers or modules, atomic layer deposition (ALD) chambers or modules, atomic layer etch (ALE) chambers or modules, ion implantation chambers or modules, track chambers or modules, and any other semiconductor processing systems that can be associated with or used in the fabrication and / or manufacture of semiconductor wafers.

[0193] As described above, depending on one or more process steps to be performed by the tool, the controller can communicate with one or more other tool circuits or modules, other tool components, integrated tools, other tool interfaces, adjacent tools, neighboring tools, tools located throughout the factory, a host, another controller, or tools used in a material handling that transports a container of wafers between tool locations and / or load ports in a semiconductor manufacturing factory.

[0194] Suitable apparatus for performing the methods disclosed herein are further discussed and described in U.S. Patent No. 8,728,956, issued May 20, 2014, and entitled "Plasma-activated conformal film deposition," filed April 11, 2011; and U.S. Patent Application No. 13 / 084,305, filed April 11, 2011, and entitled "SILICON NITRIDE FILMS AND METHODS," the entire contents of which are incorporated herein by reference.

[0195] The apparatus and methods described herein can be used in conjunction with lithographic patterning tools or processes, such as for fabricating or preparing semiconductor devices, displays, LEDs, photovoltaic panels, etc. Typically, but not necessarily, such tools / processes will be used or performed in a common manufacturing facility. Lithographic patterning of a film generally includes some or all of the following operations, each of which can be performed using a variety of available tools: (1) applying a photoresist to a workpiece, i.e., a substrate, using a spin coater or spray tool; (2) curing the photoresist using a hot plate or oven or UV curing tool; (3) exposing the photoresist to visible light or ultraviolet or X-rays using a tool such as a wafer stepper; (4) developing the resist to selectively remove the resist using a tool such as a wet bench, thereby patterning it; (5) transferring the resist pattern to an underlying film or workpiece by using a dry or plasma-assisted etch tool; and (6) removing the resist using a tool such as a radio frequency or microwave plasma resist stripper.

[0196] Experiment

[0197] Experiment 1

[0198] Experiments were conducted on the deposition of a silicon nitride (SiN) encapsulation layer. A first substrate containing 4:1 aspect ratio features was exposed to silane (SiH 4 ) and a mixture of nitrogen and ammonia (N 2 / NH 3 ) to deposit the SiN encapsulation layer. The first substrate achieved a step coverage of 40%.

[0199] While the plasma was turned on at a pulse frequency of 0.02 milliseconds and off for 1.98 milliseconds and pulsed between 0 W and 500 W at a plasma frequency of 13.56 MHz, a second substrate containing 4:1 aspect ratio features was continuously exposed to SiH 4 and N 2 / NH 3 at 300 °C to deposit a 300 angstrom SiN encapsulation layer. The bottom-to-top ratio of the deposited film was 68% and the sidewall-to-top ratio was 71%. An example of the resulting substrate is Figure 9 shown. Figure 9 includes a substrate 901 having TEOS 903 and a SiN layer 905 deposited at low pressure and a silicon oxide film 907 deposited by ALD. A silicon nitride layer 909 deposited by pulsed PECVD as described herein was conformally deposited with a step coverage of 70% on the substrate.

[0200] Experiment 2

[0201] Experiments were conducted that included exposing a non-pulsed PECVD deposited SiN encapsulation layer to periodic plasma post-treatment. A substrate including the deposited SiN encapsulation layer deposited by non-pulsed PECVD was exposed to a plasma with an argon / helium post-treatment gas for a post-treatment operation for 30 seconds at a power of 2000 W and a plasma frequency of 13.56 MHz. The substrate was exposed to the following exposure sequence: (a) plasma on for 0.02 milliseconds, (b) plasma off for 1.98 milliseconds, (c) repeat (a) and (b), (d) post-treatment with an inert plasma for 10 s - 60 s, (e) repeat (a)-(d).

[0202] The FTIR spectra of both the as-deposited substrate (dashed line) and the substrate treated only with periodic plasma (solid line) are Figure 10 shown. As shown, the solid line shows a weakening of the Si-H bond, which indicates a reduction in hydrogen content and an enhancement of the densification peak, both of which indicate the production of a higher quality film by periodic plasma treatment.

[0203] Experiment 3

[0204] Experiments were conducted for exposing a SiN encapsulation layer deposited by non-pulsed PECVD to a post-treatment of UV exposure. Substrates containing the deposited SiN encapsulation layer deposited by non-pulsed PECVD were exposed to UV radiation at a temperature of 300 °C for a duration of 300 seconds at wavelengths from 180 nm to 600 nm. The FTIR spectra of only the deposited substrates (solid line) and the substrates treated with UV (dashed line) are as Figure 11 shown. As shown, the dashed line shows a weakening of the N-H bond at 1101, indicating a decrease in hydrogen content; a weakening of the Si-H bond at 1103, which also indicates a reduction in hydrogen content; and an enhancement of the densification peak at 1105. These features indicate that the UV treatment produced a higher-quality film.

[0205] Experiment 4

[0206] Deposition experiments of the encapsulation layer were carried out at 250 °C using remote plasma chemical vapor deposition.

[0207] By introducing nitrogen radicals from a remote plasma to the substrate, and delivering silane onto the substrate downstream of the showerhead, and setting the pedestal holding the substrate at a temperature of 250 °C, an encapsulation layer was deposited on a first substrate with an aspect ratio feature of 4:1 in an RPCVD chamber containing a showerhead. The step coverage of the deposited film was greater than 80%.

[0208] A SiCO encapsulation layer was deposited on a second substrate with an aspect ratio feature of 7:1 in an RPCVD chamber containing a showerhead by introducing radicals from a remote plasma to the substrate, and delivering a silicon-containing precursor onto the substrate downstream of the showerhead, and setting the pedestal holding the substrate at a temperature of 250 °C. Figure 12A The substrate before performing the wet etching rate experiment is shown. Substrate 1200 has an underlying layer 1201 and TEOS 1203, with a SiN layer 1207 deposited at a low pressure and a SiCO encapsulation layer 1209 conformally deposited on the substrate. Note the conformality indicated by arrow 1219.

[0209] The substrate was exposed to a 100:1 diluted HF solution for 5 minutes. Figure 12B The substrate 1220 after this exposure is shown. As shown, the top and sidewalls of the feature indicated by arrow 1229 do not show etching, indicating that the wet etching rate of the deposited encapsulation layer 1209 is close to 0.

[0210] Experiment 5

[0211] Experiments were conducted by various methods to deposit the encapsulation layer. Four deposition methods were carried out on the substrate. The first method included using conventional PECVD exposed to continuous plasma (continuous exposure to a silicon-containing precursor and a second reactant with continuous plasma), without post-treatment. The plasma power was set to 500 W and the plasma frequency was 13.5 MHz. This method is represented as white bars (1302) in Figure 13A and 13B .

[0212] The second method involved pulsed PECVD (continuous exposure to a silicon-containing precursor and a second reactant with pulsed plasma), without post-treatment. The plasma was pulsed between 0 W and 500 W with a duty cycle of 10% and a pulse frequency of 500 Hz. This method is represented as diagonal striped bars (1304) in Figure 13A and 13B .

[0213] The third method involved pulsed PECVD (continuous exposure to a silicon-containing precursor and a second reactant with pulsed plasma), with periodic plasma post-treatment. The plasma during the pulsed plasma deposition process was pulsed with a pulse frequency of 500 Hz, between 0 W and 500 W, with a 0.2 ms RF on / 1.8 ms RF off pulse. During the periodic plasma post-treatment, the plasma was turned on for 60 seconds, the plasma power was 2000 W (4 stations, power density = 0.6 W / cm 2 ), and the plasma frequency was 13.56 MHz. This method is shown as horizontal striped bars (1306) in Figure 13A and 13B .

[0214] The fourth method included using conventional PECVD exposed to continuous plasma (continuous exposure to a silicon-containing precursor and a second reactant with continuous plasma) with periodic plasma post-treatment. The plasma power was set to 500 W and the plasma frequency was 13.56 MHz. The film was deposited using continuous plasma for several seconds to deposit 25 Å - 30 Å. Then the film was exposed to plasma post-treatment with a duration of 60 seconds, plasma power of 2000 W, and plasma frequency of 13.56 MHz. This cycle was repeated until the entire film thickness was reached. This method is represented as shaded bars (1308) in Figure 13A and 13B .

[0215] The process conditions for process conditions A, B, and C as shown in Figure 13A and 13B are outlined in Table 1 below.

[0216] Table 1. Process conditions for deposition section

[0217]

[0218] Figure 13A Shows the resulting hydrogen content of substrates exposed to each set of process conditions and deposited by each of the four methods. For process condition A, the hydrogen content of the substrates treated with periodic plasma is less than that of the substrates treated with pulsed plasma and periodic plasma, and the hydrogen content of both of these methods is lower than that of the substrates subjected to continuous plasma treatment and the substrates treated with pulsed plasma without post-treatment. This indicates that periodic plasma post-treatment reduces the hydrogen content. In addition, in some embodiments, pulsed plasma with post-treatment may be a viable and suitable option.

[0219] For process condition B, the hydrogen content of the substrates subjected to pulsed plasma is the highest, which indicates that at high temperature (400 °C), pulsed plasma may not be suitable in some embodiments, but the combination of pulsed plasma and periodic plasma treatment significantly reduces the hydrogen content. Periodic plasma treatment alone also results in a low hydrogen content. These results show that even when deposited at 400 °C, the combination of pulsed plasma deposition and periodic plasma treatment, or periodic plasma treatment alone can result in a low content of the film.

[0220] For process condition C, the hydrogen content of the substrates treated with both continuous plasma and pulsed plasma is high, but the combination of either with periodic plasma treatment results in a significant reduction in the hydrogen content, which further supports for some embodiments that even when the substrates are deposited at 400 °C, periodic plasma treatment can be applied to reduce the hydrogen content. The results show that post-treatment reduces the hydrogen content and the wet etch rate.

[0221] Figure 13B Shows when subjected to a 200:1 hydrofluoric acid etchant, Figure 13A the resulting wet etch rate of each substrate. For process condition A, the wet etch rate of the substrates with an encapsulation layer deposited by pulsed plasma, with an encapsulation layer deposited by pulsed plasma and periodic plasma treatment, and with an encapsulation layer deposited by periodic plasma treatment is lower than that of the substrates with an encapsulation layer deposited by continuous plasma. The wet etch rate of the encapsulation layer deposited and subjected to periodic plasma treatment is even lower than that of the encapsulation layer deposited by pulsed plasma without post-treatment. The lower wet etch rate indicates a higher quality of the film, and thus it can withstand exposure to more demanding conditions in subsequent processing, allowing the encapsulation layer to effectively protect the underlying memory stack.

[0222] For process condition B, a similar trend is shown because the encapsulation layer that also undergoes periodic plasma treatment results in a lower wet-etch rate than the layer without post-treatment. Similarly, for process condition C, a similar trend is also shown, where the wet-etch rate of the encapsulation layer deposited and subjected to periodic plasma treatment is significantly lower compared to the layer without periodic plasma treatment.

[0223] Conclusion

[0224] Although the foregoing embodiments have been described in some detail for purposes of clear understanding, it will be apparent that certain changes and modifications may be practiced within the scope of the appended claims. It should be noted that there are many alternative ways of implementing the methods, systems, and devices of this embodiment. Therefore, this embodiment is considered illustrative rather than restrictive, and the embodiments are not limited to the details given herein.

Claims

1. A method for encapsulating a memory device on a substrate in a processing chamber, the method comprises: exposing the substrate having the memory device located in the processing chamber to a deposition precursor at a substrate temperature below 300 °C; generating a reactive species in a remote plasma generator; and introducing the reactive species into the processing chamber to react with the deposition precursor to deposit an encapsulation layer over the memory device, wherein the encapsulation layer deposited on the memory device has a step coverage between 70% and 90%; wherein the encapsulation layer is selected from silicon nitride, undoped silicon carbide, oxygen-doped silicon carbide, germanium nitride, undoped germanium carbide, and oxygen-doped germanium carbide, wherein depositing the encapsulation layer comprises: (a) flowing a reactant gas stream to a remote plasma generation region and igniting a plasma to generate the reactive species including reactant free radicals; (b) introducing the reactant free radicals into the substrate through a showerhead; and (c) introducing the deposition precursor downstream of the showerhead into the substrate while introducing the reactant free radicals.

2. The method according to claim 1, further comprising exposing the encapsulation layer to a post-treatment process to form a hermetic encapsulation layer, wherein the post-treatment process is performed at a temperature below 300 °C.

3. The method according to claim 1, wherein the encapsulation layer is deposited by remote plasma enhanced chemical vapor deposition.

4. The method according to claim 1, further comprising exposing the encapsulation layer to a post-treatment process to form a hermetic encapsulation layer, wherein the post-treatment process comprises exposing the substrate to a post-treatment gas and igniting a second plasma in the absence of reactants.

5. The method according to claim 4, wherein the substrate is exposed to the post-treatment gas and the second plasma for a duration between 10 seconds and 50 seconds.

6. The method according to claim 4, wherein the post-treatment gas is selected from nitrogen, ammonia, helium, argon, and combinations thereof.

7. The method according to claim 1, wherein the memory device is a magnetoresistive random access memory.

8. The method according to claim 1, wherein the memory device comprises a magnetic tunnel junction.

9. The method according to claim 1, wherein the encapsulation layer is deposited to a thickness between 50 angstroms and 500 angstroms.

10. The method according to claim 1, wherein the encapsulation layer is deposited by plasma enhanced chemical vapor deposition.

11. The method according to claim 1, wherein the encapsulation layer is a silicon nitride film deposited by exposing the substrate to a silicon-containing precursor and a nitrogen-containing reactant.

12. The method according to claim 1, wherein the encapsulation layer is a silicon carbide film deposited by exposing the substrate to a silicon- and carbon-containing precursor and hydrogen.

13. The method according to claim 1, further comprising heating the substrate to a temperature of 300 °C before depositing the encapsulation layer.

14. The method according to claim 1, wherein the reactive species comprises nitrogen gas and an inert gas.

15. A method for encapsulating a memory device on a substrate in a processing chamber, the method Comprising: Exposing the substrate having a memory device located in the processing chamber to a deposition precursor and a reactant at a substrate temperature below 300°C; And Introducing reactive species in a pulsed plasma into the processing chamber to react with the deposition precursor, thereby depositing a capping layer over the memory device, the capping layer having a step coverage between 70% and 90%; Wherein the capping layer is selected from silicon nitride, undoped silicon carbide, oxygen-doped silicon carbide, germanium nitride, undoped germanium carbide, and oxygen-doped germanium carbide.

16. The method according to claim 15, further comprising exposing the capping layer to a post-treatment process to form a hermetic capping layer, wherein the post-treatment process is performed at a temperature below 300°C.

17. The method according to claim 15, wherein the pulse of the pulsed plasma has a duration between 0.02 milliseconds and 5 milliseconds.

18. The method according to claim 15, wherein the pulsed plasma is pulsed at a pulse frequency between 100 Hz and 6 Hz.

19. The method according to claim 15, wherein the pulsed plasma is generated within a remote plasma generator.

20. The method according to claim 15, wherein the capping layer is deposited by remote plasma enhanced chemical vapor deposition.

21. The method according to claim 20, wherein remote plasma enhanced chemical vapor deposition Comprises: (a) Flowing a reactant gas to a remote plasma generation region and pulse-igniting the plasma to generate the reactive species including reactant radicals; (b) Introducing the reactant radicals into the substrate through a showerhead; And (c) Introducing the deposition precursor downstream of the showerhead into the substrate when introducing the reactant radicals.

22. The method according to claim 15, further comprising exposing the capping layer to a post-treatment process to form a hermetic capping layer, wherein the post-treatment process comprises exposing the substrate to a post-treatment gas and igniting a second plasma in the absence of reactants.

23. The method according to claim 22, wherein the substrate is exposed to the post-treatment gas and the second plasma for a duration between 10 seconds and 50 seconds.

24. The method according to claim 22, wherein the post-treatment gas is selected from nitrogen, ammonia, helium, argon, and combinations thereof.

25. The method according to claim 15, wherein the memory device is a magnetoresistive random access memory.

26. The method according to claim 15, wherein the memory device comprises a magnetic tunnel junction.

27. The method according to claim 15, wherein the capping layer is deposited to a thickness between 50 angstroms and 500 angstroms.

28. The method according to claim 15, wherein the capping layer is deposited by plasma enhanced chemical vapor deposition.

29. The method according to claim 15, wherein the capping layer is a silicon nitride film deposited by exposing the substrate to a silicon-containing precursor and a nitrogen-containing reactant.

30. The method according to claim 15, wherein the encapsulation layer is a silicon carbide film deposited by exposing the substrate to silicon- and carbon-containing precursors and hydrogen.

31. The method according to claim 15, further comprising heating the substrate to a temperature of 300 °C before depositing the encapsulation layer.

32. The method according to claim 15, wherein the reactive species includes nitrogen gas and an inert gas.

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