Antioxidant protection layer in room conditioning

Abstract

In some examples, a method for conditioning a wafer processing chamber includes: setting a pressure in the chamber to a predetermined pressure range; setting a temperature in the chamber to a predetermined temperature range; and supplying a process gas mixture to a gas distribution device in the chamber. A plasma is ignited in the chamber and a state in the chamber is monitored. A chamber conditioning operation is performed based on detecting that the monitored state reaches or crosses a threshold. The chamber conditioning operation may include: depositing a pre-conditioning film on an inner surface of the chamber, depositing a silicon oxycarbide (SiCO) film on the pre-conditioning film, and depositing a protective layer on the SiCO film.

Description

[0001] Priority claim

[0002] This patent application claims the benefit of priority to U.S. Provisional Patent Application Serial No. 62 / 595,948, filed on December 7, 2017, the entire contents of which are hereby incorporated by reference herein. Technical Field

[0003] The present disclosure relates generally to processing and conditioning cycles in wafer processing chambers, and more particularly to defect reduction and batch size extension by utilizing an anti-oxidation protective layer in wafer processing and chamber conditioning operations. Background Art

[0004] The background description provided here is for the purpose of generally presenting the context of the present disclosure. Work by the presently designated inventors to the extent described in this background section and in aspects of the description that could not be determined as prior art at the time of filing the application is neither explicitly nor implicitly admitted to be prior art against the present disclosure.

[0005] Over time, repeated wafer processing cycles in the processing chamber may cause various types of films to accumulate on the chamber walls. As the film height (level) gradually grows on the components in the reaction chamber, film stress may increase, and the adhesion between the accumulated film and the chamber surface may significantly deteriorate over time. This loss of adhesion may cause parts of the accumulated film to peel off from the chamber wall. When there is too much film accumulation in the chamber, the accumulated film will not adhere well to the chamber wall and it begins to peel off. Flakes and parts of the peeled film may fall on the wafer in the processing chamber and appear as particles or defects themselves. In some cases, oxygen-rich plasma exacerbates film peeling because first it may cause the accumulated film to shrink, resulting in higher tension, and secondly, it may consume carbon materials in the accumulated film, thereby causing further degradation of film adhesion. Summary of the invention

[0006] In some examples, a method for regulating a wafer processing chamber includes: setting a pressure in the chamber to a predetermined pressure range; setting a temperature of the chamber to a predetermined temperature range; supplying a process gas mixture to a gas distribution device in the chamber, wherein the process gas mixture includes a gas containing at least an oxygen species and helium or argon; igniting a plasma in the chamber; monitoring a state in the chamber; and performing a chamber regulation operation based on detecting that the monitored state reaches or crosses a threshold, wherein the chamber regulation operation includes: depositing a pre-conditioning film on an inner surface of the chamber, depositing a silicon oxycarbide (SiCO) film on the pre-conditioning film, and depositing a protective layer on the SiCO film. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Some embodiments are described by way of example and not limitation in the figures of the accompanying drawings:

[0008] Figure 1 is a schematic diagram of a wafer processing chamber in which some exemplary methods of the present disclosure may be used.

[0009] Figure 2 A graph showing results of film shrinkage and stress according to some exemplary embodiments.

[0010] Figure 3A-3B Comparative graphs of measured defect properties are shown according to some exemplary embodiments.

[0011] Figure 4 is a cross-sectional view of a composite protective layer according to an exemplary embodiment.

[0012] Figure 5 A flowchart depicting operations in a method according to an exemplary embodiment is provided. DETAILED DESCRIPTION

[0013] The following description includes systems, methods, techniques, instruction sequences, and computer program products that implement illustrative embodiments of the present invention. In the following description, for the purpose of illustration, a large number of specific details are described to provide a thorough understanding of the exemplary embodiments. However, it is apparent to those skilled in the art that the subject matter of the present invention can be practiced without these specific details.

[0014] Portions of the disclosure of this patent document contain material that is subject to copyright protection. The copyright owner has no objection to the facsimile reproduction by anyone of the patent document or the patent disclosure, as it appears in the Patent and Trademark Office patent files or records, but otherwise reserves all copyright rights whatsoever. The following notice applies to any data described below and in the accompanying drawings that constitute a part of this document: Copyright Lam Research Corporation, 2018, All Rights Reserved.

[0015] As a prior art, a wafer processing chamber (such as Striker Carbide TM The process chamber) allows remote plasma chemical vapor deposition (RPCVD) technology to produce highly conformal silicon carbide films. Some highly conformal silicon carbide films are called SPARC TMFilm. At many times during a wafer processing cycle in a chamber, a chamber cleaning or conditioning operation may be required. Chamber cleaning may be required when defect performance on a wafer deviates from specifications. As described above, if too much film accumulates in the chamber, the accumulated film may begin to peel off and deposit particles on the processed wafer. This may lead to a high degree of defects in chips and devices made from the wafers processed in the chamber. A chamber cleaning operation may remove some or all of the accumulated film to bring defect performance back into specification again.

[0016] After the chamber is cleaned, atomic layer deposition (ALD) is typically used to deposit a thin layer of an oxide film (also called a preconditioning film) on one or more interior surfaces of the processing chamber, and then RPCVD is used to deposit another thin layer of a silicon oxycarbide (SiCO) film. In some cases, the cumulative film thickness in the chamber consists only of SiCO. Since SiCO films are easily oxidized, further film deposition on wafers processed in the chamber by oxygen-rich plasma exacerbates the oxidation problem. Therefore, applying a SiCO film after cleaning does not necessarily solve the problem of degraded defect performance. In other words, the "defect performance" of a processing chamber, or its ability to prevent defects from occurring in wafers processed therein, can become increasingly worse over time.

[0017] In other conventional methods, when SPARC TM Before film deposition on the wafer, a wafer preconditioning operation can be performed to TM The film modifies the surface state of the substrate (wafer) when applied to the wafer. The wafer preconditioning step may include, for example, applying a starting layer to the wafer surface and surface treating it. However, even during this wafer preconditioning operation, the film layer on the chamber surface may still be attacked by the oxygen-rich plasma. The plasma may reduce the thickness of the preconditioning film on the chamber surface and other accumulated film layers on the chamber surface. The thickness reduction (or shrinkage) may cause the "stress" of the accumulated film on the chamber surface (including, for example, the chamber wall and the showerhead) to become more tensile in nature, while the adhesion of the preconditioning film to subsequent film layers may itself be affected for similar reasons. These shrinkage and stress effects may lead to early degradation of wafer performance, reduced chamber defect performance, more on-wafer defect occurrences, and reduced batch size, which is caused by rejecting defective chips or other devices from affected wafers.

[0018] In some examples of the present disclosure, the problems discussed above are addressed by implementing periodic chamber conditioning, which produces a high carbon content and oxidation resistant protective layer on the chamber surface to compensate for film stress and mitigate the effects of oxygen-rich plasma erosion on the pre-conditioned film. Example triggering conditions for chamber conditioning may include, but are not limited to, detecting a degradation in defect performance level approaching or reaching a threshold, or detecting a level of cumulative film stress approaching or reaching a threshold. In some examples, the threshold may be related to the thickness of the cumulative film in the chamber, the cumulative film thickness being in the range of 0.05 to 0.5 μm (micrometers).

[0019] In some examples, a protective layer is formed on the chamber surface by chemical vapor deposition (CVD). Exemplary chemicals used in the deposition reaction include silicon-containing substances such as silane or disilane, oxygen-containing substances such as oxygen or carbon dioxide, and diluent gases such as hydrogen or helium. The reaction may occur at a pressure in the range of 0.1 to 10 Torr and at a temperature in the range of 100°C to 600°C. When a threshold chamber film accumulation (e.g., a thickness in the range of 0.05 to 0.5 μm) is reached, the chamber stops processing additional wafers. In some examples, the processing stop may occur automatically when a threshold accumulated thickness is detected. In some examples, the processing chamber is further configured to begin depositing a protective layer thereafter without a wafer being supported in the processing chamber. The thickness of the protective layer may vary depending on the type of wafer processing. Exemplary thicknesses may fall within the range of 50 nanometers (nm) to 1 micrometer (μm). In some examples, after the initial protective layer is deposited on the surface of the processing chamber, the processing chamber may continue to process the wafer until the chamber film accumulation increases to a further threshold thickness (e.g., the thickness doubles). Other thresholds are possible. When further thresholds are reached or approached, a protective layer may be deposited again onto the initial layer to maintain the defect performance of the chamber within a given specification. In some examples, the deposition cycle of the protective layer continues until a composite protective film is formed. In some examples, the formation of the composite protective film continues until its outer layer fails to adhere to the composite film, or until the following situation: the rupture of the outer layer fails to prevent the initial film previously coated on the inner surface of the chamber from peeling off and causing defects and other problems on the wafer in the above-mentioned manner.

[0020] A cross-sectional view of an exemplary protective layer having a membrane element layer generally designated 400 is shown in Figure 4. The protective layers 400A-N in this example are formed above the pre-conditioning film 404, which is formed on the surface 402 of the chamber wall. The illustrated protective layers 400A-N form a composite protective layer in this example, which will be referred to as a composite protective film for clarity. Other examples of composite protective films and layers therein are possible. The composite protective films 400A-N may be formed over time, for example, by performing one or more of the operations further described above. The composite protective films 400A-N may include repeating or alternating SiCO layer and protective layer pairs, such as shown in the continuous layers 400A to 400N. The formation of the paired SiCO layers and protective layers may be repeated cycles to expand the composite protective film 400 until a threshold of the monitored chamber state is reached. An exemplary threshold may be the thickness of the composite protective film, such as shown by the outer surface of the paired layer 400N.

[0021] In some cases, to improve the process chamber (e.g., Striker Carbide TM In order to reduce the defect performance of the pre-conditioning chamber (i.e., to minimize wafer defects), a protective layer is generated on one or more chamber surfaces to minimize film damage caused by the pre-conditioning operation. Once a certain film accumulation in the reaction chamber is detected based on, for example, one or more of the above thresholds, a protective layer comprising a high carbon content SiCO film is deposited on one or more chamber surfaces. In some examples, the inherent stress of the protective layer is compressive in nature, so it can fully or partially compensate for any tensile stress caused by shrinkage of the pre-conditioning film thickness or by the oxygen-rich plasma in the previously applied pre-conditioning film. Such film stress reduction or shrinkage compensation can help inhibit film cracking and flaking caused by high tensile stress.

[0022] In some examples, due to the presence of excess carbon atoms in the protective layer, the protective layer can further serve as a sacrificial layer to prevent the effects of oxygen-rich plasma erosion. The excess carbon atoms are sacrificially consumed by the oxygen-rich plasma. Therefore, the carbon content of the remaining pre-conditioned film in the reaction chamber can be similar to that of, for example, SPARC, which has known excellent adhesion properties and defect performance. TM The methods and systems disclosed herein can significantly improve and maintain the performance of process chambers (e.g., StrikerCarbide TM In addition, the improved chamber processing described herein can produce batch sizes that are 250% larger than conventional examples. Some examples facilitate film deposition at high deposition rates, such as 50 to 500 angstroms for high carbon protective layers. Some exemplary high carbon protective layers contain between 30% and 45% carbon by weight. Some exemplary protective layers have relatively low desired thicknesses, so the impact on production throughput by producing such protective layers is minimal. Testing performed using the methods described herein showed that in some examples, batch size can be improved by 250% while maintaining satisfactory defect performance of the processing chamber that achieves such batch size improvement.

[0023] An example chamber in which some exemplary operations of the present disclosure may be used (and appropriate chamber modifications for film deposition and control testing) is shown in the accompanying drawings. Figure 1 In. Plasma etching (or deposition) equipment includes a reactor in which there is a chamber through which one or more reactive gases flow. Within the chamber, these gases are ionized into a plasma, usually by radio frequency energy. The highly reactive ions of the plasma gas are capable of reacting with materials (e.g., a polymer mask on the surface of a semiconductor wafer being processed into an integrated circuit (IC)). The plasma gas (e.g., an oxygen-rich plasma gas) can react with other materials in the chamber (e.g., a pre-conditioning film or a protective film) in the manner described above.

[0024] Prior to etching, the wafer is placed in the chamber and held in place by a chuck or holder that exposes the top surface of the wafer to the plasma gas. There are several types of known chucks in the prior art. The chuck provides an isothermal surface and acts as a heat sink for the wafer. In one type, the semiconductor wafer is held in place for etching by mechanical clamping. In another type of chuck, the semiconductor wafer is held in place by electrostatic forces generated by an electric field between the chuck and the wafer. These methods are applicable to both types of chucks.

[0025] Figure 1 An exemplary capacitively coupled plasma processing chamber 100 is shown, which represents an exemplary plasma processing chamber of the type typically used to etch or perform film deposition on a substrate. A chuck 102 represents an exemplary workpiece holder on which a substrate (e.g., a wafer 104) may be positioned during etching or deposition. The chuck 102 may be implemented by any suitable clamping technique (e.g., electrostatic, mechanical, clamping, vacuum, etc.). During etching, the chuck 102 is typically supplied with dual RF frequencies (low frequency and high frequency), such as 2 MHz and 27 MHz, simultaneously during etching via a dual frequency source 106.

[0026] The upper electrode 108 is located above the wafer 104. The upper electrode 108 is grounded. Figure 1An etch reactor is shown in which the surface of the upper electrode 108 is larger than the surface of the chuck 102 and the wafer 104. During etching, a plasma 110 is formed from an etchant source gas supplied through a gas line 112 and pumped out through an exhaust line 114. An electrical insulator ring 109 insulates the upper electrode 108 from the grounded chamber 100. A confinement ring 116 may be disposed between the upper electrode 108 and a lower electrode (e.g., Figure 1 Generally, confinement ring 116 assists in confining etching plasma 110 to a region above wafer 104 to improve process control and ensure reproducibility.

[0027] When RF power is supplied to the chuck 102 from the dual frequency power source 106, equipotential field lines are set above the wafer 104. Equipotential field lines are electric field lines that span the plasma sheath, which is located between the wafer 104 and the plasma 110. During plasma processing, positive ions are accelerated across the equipotential field lines and impact on the surface of the wafer 104, thereby providing the desired etching effect, such as improved etching directionality. Due to the geometry of the upper electrode 108 and the chuck 102, the field lines may not be uniform across the wafer surface and may vary significantly at the edge of the wafer 104. Therefore, a focus ring 118 is typically provided to improve processing uniformity across the wafer surface. Reference Figure 1 , the wafer 104 is shown disposed within a focus ring 118, which may be formed of a suitable dielectric material (e.g., ceramic, quartz, plastic, etc.). Thus, the presence of the focus ring 118 enables equipotential field lines to be substantially uniformly disposed over the entire surface of the wafer 104.

[0028] The conductive shield 120 substantially surrounds the focus ring 118. The conductive shield 120 is configured to be substantially grounded within the plasma processing chamber. The shield 120 prevents unwanted equipotential field lines from existing outside the focus ring 118.

[0029] Now referring to the accompanying drawings Figure 2 , which shows a table 200 of exemplary film stress and thickness shrinkage results. Here, in some examples, a reference film is formed on a test wafer without a chamber preconditioning step as a control example. A first comparative hybrid film is produced on another test wafer using the same total deposition time as the reference film, but in this case, a conventional chamber preconditioning step of the type described further above is performed successively for each tenth of film thickness in the process of producing the first hybrid film for a total of ten times. Figure 2 As can be seen in Table 200 of FIG. 2, the preconditioning operation caused the film stress to increase by nearly 400% from an initial value of 23.9 MPa for the control baseline film to a value of 99 MPa for the pressurized first hybrid film. In addition, the film experienced shrinkage (thickness reduction) from the control baseline film's To the first hybrid membrane

[0030] Depicted on Figure 3A-3B The comparison results in the graph of FIG. 1 relate to a second hybrid film. The second hybrid film was formed on a test wafer processed in a chamber conditioned by using a protective layer as exemplified herein. A quadrant module containing four stations labeled Stn1 to Stn4 in the figure was used to measure the particle size (defects) present in the various deposited layers in each film that was set up for testing. The pressurized first hybrid film (above) Figure 2 The results of the types tested in Figure 3A The results for the second hybrid membrane formed in the conditioned (protected) chamber of the present disclosure are shown in FIG. Figure 3B In. Figure 3A-3B In both views, particle (defect) size is shown on the left vertical axis of the diagram, and film thickness (or accumulation) is shown along the bottom horizontal axis for each of the four measurement stations.

[0031] As shown in the figure, for Figure 3A For the first hybrid film under pressure shown in , particle sizes greater than 50 nm (ie, defects) suddenly increase at a film thickness of approximately 0.8 μm at each of the four stations. Figure 3B Very few, if any, defects were found in the adjusted second hybrid film results shown in , even at a film thickness depth of about 2 μm (e.g., 1.904 μm) of Stnl. Individual values ​​for the upper control limit (UCL) (e.g., set at three standard deviations), the lower control limit (LCL), and the average are shown, and Figure 3B The conditioned second hybrid membrane showed significant improvement.

[0032] In view of the above, a usable batch size based on the exemplary film results shown (i.e., the height of the film deposited on the wafer between chamber cleans) can be established at 0.8 μm, since significant defects can be seen to occur at greater film thicknesses. Conversely, for films conditioned according to the methods of the present disclosure, a usable batch size can be established even at film thicknesses of about 2 μm or more, since no significant defects appear to occur below this exemplary value.

[0033] Some embodiments of the present disclosure include methods. Figure 5, a method 500 for regulating a wafer processing chamber includes: at operation 502, setting a pressure in the chamber to a predetermined pressure range; at operation 504, setting a temperature of the chamber to a predetermined temperature; at operation 506, supplying a process gas mixture to a gas distribution device in the chamber, wherein the process gas mixture includes a gas containing at least an oxygen species and helium or argon; at operation 508, igniting a plasma in the chamber; at operation 510, monitoring a state in the chamber; at operation 512, performing a chamber regulation operation based on detecting that the monitored state reaches or crosses a threshold, wherein the chamber regulation operation includes: at operation 514, depositing a pre-conditioning film on an inner surface of the chamber, at operation 516, depositing a silicon oxycarbide (SiCO) film on the pre-conditioning film, and at operation 518, depositing a protective layer on the SiCO film.

[0034] Some aspects of method 500 may include the following features or operations. In some examples, the monitored state includes chamber defect performance. In some examples, the monitored state includes film stress values. In some examples, the monitored state includes film cumulative thickness on the inner surface of the chamber. In some examples, the film cumulative thickness is in the range of 0.05 to 0.5 μm (micrometer).

[0035] In some examples, the protective layer is formed by chemical vapor deposition (CVD). Chemicals used in the CVD reaction may include silicon-containing substances, such as silane or disilane.

[0036] In some examples, the predetermined chamber pressure range during the protective layer deposition is in the range of 0.1 to 10 Torr. In some examples, the predetermined chamber temperature range during the protective layer deposition is in the range of 100° C. to 600° C. In some examples, the thickness of the protective layer is in the range of 50 nanometers (nm) to 1 micrometer (μm).

[0037] In some examples, the operations of depositing a silicon oxycarbide (SiCO) film on the preconditioning film and depositing a protective layer on the SiCO film are sequentially repeated to form a pair of SiCO film and protective layer in the composite protective film.

[0038] In some examples, the protective layer is a high carbon, oxidation resistant protective layer comprising 30% to 45% carbon by weight.

[0039] In some examples, method 500 further includes performing a step of heating at 50 to 500 angstroms. The protective layer is deposited at a deposition rate within a range of .

[0040] In some examples, igniting the plasma includes supplying HF power in a range of 500 to 6000 W to one of the upper electrode and the lower electrode, and supplying LF power in a range of 500 to 6000 W to the one of the upper electrode and the lower electrode. In some examples, igniting the plasma includes supplying HF power in a range of 2000 to 4000 W to one of the upper electrode and the lower electrode, and supplying LF power in a range of 1000 to 4000 W to the one of the upper electrode and the lower electrode.

[0041] Although the embodiments have been described with reference to specific exemplary embodiments, it is apparent that various modifications and changes may be made to these embodiments without departing from the broader spirit and scope of the subject matter of the present invention. Therefore, the specification and the drawings are to be regarded as illustrative rather than restrictive. The drawings constituting a part of this document show specific embodiments in an illustrative (but not limiting) manner in which the subject matter may be implemented. The illustrated embodiments are described in sufficient detail to enable those skilled in the art to implement the teachings disclosed herein. Other embodiments may be utilized and derived therefrom so that structural and logical substitutions and changes may be made without departing from the scope of the present disclosure. Therefore, this detailed description is not to be regarded as limiting, and the scope of the various embodiments is defined only by the appended claims and the full scope of equivalents to which these claims are assigned.

[0042] Such embodiments of the subject matter of the present invention may be referred to herein individually and / or collectively by the term "invention", which is merely for convenience and is not intended to voluntarily limit the scope of the present application to any single invention or inventive concept (if more than one invention or inventive concept is in fact disclosed). Therefore, although specific embodiments are shown and described herein, it should be understood that any configuration calculated to achieve the same purpose may replace the specific embodiments shown. The present disclosure is intended to cover any and all adjustments or variations of the various embodiments. After reading the above description, combinations of the above embodiments and other embodiments not specifically described herein will be apparent to those skilled in the art.

Claims

1. A method for adjusting a substrate processing chamber, the method comprising: Setting the pressure in the substrate processing chamber to within a predetermined pressure range; Setting the temperature of the substrate processing chamber to within a predetermined temperature range; supplying a process gas mixture to a gas distribution device within the substrate processing chamber, wherein the process gas mixture includes a gas containing at least an oxygen species and helium or argon; Ignite a plasma within the substrate processing chamber: monitoring a condition in the substrate processing chamber; Detecting that the monitored state reaches or crosses a threshold; Performing a substrate processing chamber adjustment operation based on detecting that the monitored state reaches or crosses a threshold, wherein the substrate processing chamber adjustment operation includes: In the substrate processing chamber, a preconditioning film is deposited on an inner surface of the substrate processing chamber by atomic layer deposition, depositing a silicon oxycarbide film on the preconditioning film by remote plasma chemical vapor deposition in the substrate processing chamber, and In the substrate processing chamber, a protective layer is deposited on the silicon oxycarbide film by chemical vapor deposition, wherein the protective layer has a carbon content different from that of the silicon oxycarbide film.

2. The method of claim 1, wherein the conditions monitored include chamber defect performance. The method of claim 1 , wherein the monitored state includes a film stress value.

4. The method of claim 1, wherein the condition monitored includes a thickness of film buildup on the interior surface of the substrate processing chamber.

5. The method according to claim 4, wherein the cumulative thickness of the film is in the range of 0.05 to 0.5 μm (micrometer). 6 . The method of claim 1 , wherein chemicals used in the chemical vapor deposition reaction for depositing the protective layer include silicon-containing substances. The method of claim 6 , wherein the silicon-containing substance comprises silane or disilane. 8 . The method of claim 1 , wherein the pressure in the substrate processing chamber during deposition of the protective layer is set within a range of 0.1 to 10 Torr.

9. The method of claim 1, wherein the temperature of the substrate processing chamber during the deposition of the protective layer is set within a range of 100°C to 600°C. 10 . The method of claim 1 , wherein a thickness of the protective layer is in a range of 50 nanometers (nm) to 1 micrometer (μm).

11. The method according to claim 1, wherein: The operations of depositing the silicon oxycarbide film on the preconditioning film and depositing the protective layer on the silicon oxycarbide film are sequentially and repeatedly performed to form a pair of layers of the silicon oxycarbide film and the protective layer, the pair of layers forming a composite protective film.

12. The method according to claim 1, wherein the protective layer is a high carbon anti-oxidation protective layer comprising 30% to 45% by weight of carbon.

13. The method according to claim 1, further comprising: The protective layer is deposited at a deposition rate within a range of .

14. The method of claim 1 , wherein igniting the plasma comprises: HF power in the range of 500 to 6000 W is supplied to one of the upper electrode and the lower electrode, and LF power in the range of 500 to 6000 W is supplied to the one of the upper electrode and the lower electrode.

15. The method of claim 1 , wherein igniting the plasma comprises: HF power in the range of 2000 to 4000 W is supplied to one of the upper electrode and the lower electrode, and LF power in the range of 1000 to 4000 W is supplied to the one of the upper electrode and the lower electrode.

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