Abrasive-free CMP method, abrasive-free CMP device and polished substrate

Abstract

The invention provides an abrasive-free CMP (chemical mechanical polishing) method, an abrasive-free CMP device and a polished substrate. The abrasive-free CMP method comprises the following steps: performing electrolytic activation on a polishing solution when the polishing solution is sprayed out; and / or anode current is applied to the to-be-polished substrate, so that the surface of the to-be-polished substrate is oxidized. According to the abrasive-free CMP method provided by the invention, the coordination of mechanical grinding, chemical corrosion and electrochemical reaction is realized by electrolyzing and activating the polishing solution to generate active groups and / or applying an electrochemical oxidation effect caused by anode current, the surface layer of the substrate can be efficiently removed without intervention of abrasive particles, and different polishing requirements can be flexibly met; the surface quality is improved; therefore, according to the method, the polishing rate of the to-be-polished substrate is high, and the obtained polished substrate has excellent surface quality.

Description

Technical Field

[0001] This invention belongs to the field of polishing technology, and relates to a method of abrasive-free CMP, and more particularly to a method of abrasive-free CMP, an abrasive-free CMP apparatus, and a polished substrate. Background Technology

[0002] Chemical mechanical polishing (CMP) is a key process technology for achieving global planarization of wafer surfaces in the manufacturing of very large-scale integrated circuits. As the feature size of semiconductor devices continues to shrink to the nanometer level and the three-dimensional integrated circuit structure is widely used, the requirements for wafer surface planarization quality are becoming increasingly stringent.

[0003] Traditional CMP processes use polishing slurries containing solid abrasive particles to remove material through the combined effects of mechanical friction and chemical reaction. However, this traditional method is no longer suitable for advanced manufacturing processes due to issues such as surface defects caused by abrasive particles, abrasive residue, and environmental pollution.

[0004] Abrasive-Free CMP (Chemical Motion Processing) is a revolutionary planarization solution that achieves finer surface finishes by using a special chemical solution free of solid abrasive particles, combined with an optimized polishing pad. This technology relies on a chemically-driven material removal mechanism. During polishing, the synergistic effect of oxidants, corrosion inhibitors, and other chemical components forms a soft, easily removable reactive layer on the wafer surface. The material is then removed through the mechanical friction of the polishing pad, significantly reducing surface damage.

[0005] Taking abrasive-free CMP for copper interconnects as an example, its process advantages compared to traditional CMP include superior surface quality, simplified process with abrasive-free slurry formulation, reduced costs, and improved environmental friendliness and sustainability of the slurry. Therefore, abrasive-free is a new polishing technology solution with significant development prospects.

[0006] A common core issue facing abrasive-free CMP technology is its relatively low material removal rate (MRR). For large-scale production lines requiring high efficiency, the surface layer removal rate directly impacts capacity and cost. Traditional abrasive-based CMP can typically improve the surface layer removal rate by adjusting the type, concentration, and size of the abrasive, while abrasive-free CMP relies entirely on the chemical reaction rate and mass transfer efficiency.

[0007] For example, CN119776839A discloses a method for controlling the surface roughness rate difference using abrasive-free copper CMP polishing slurry, which aims to achieve abrasive-free chemical mechanical polishing, thereby solving the problem of surface scratches caused by abrasive action during the polishing process. It is applicable to substrate polishing slurries containing copper metal layers.

[0008] For example, CN117464462A discloses a novel semiconductor CMP polishing method based on a composite CMP pipeline. The composite CMP pipeline includes a rough polishing device, a composite CMP device that combines rough and medium polishing functions, and a fine polishing device. The rough polishing device is connected to the CMP device, and the CMP device is connected to the fine polishing device.

[0009] In summary, existing abrasive-free CMP methods all have certain drawbacks, including low surface layer removal efficiency and poor surface quality after polishing. Therefore, it is crucial to develop and design a novel abrasive-free CMP method, an abrasive-free CMP apparatus, and a polished substrate. Summary of the Invention

[0010] To address the shortcomings of existing technologies, the present invention aims to provide a non-abrasive CMP method, a non-abrasive CMP apparatus, and a polished substrate. The non-abrasive CMP method provided by the present invention generates active groups by electrolytically activating the polishing slurry and / or applying an anodic current to induce electrochemical oxidation, thereby achieving the synergistic effect of mechanical grinding, chemical corrosion, and electrochemical reaction. It can efficiently remove the surface layer of the substrate without the intervention of abrasive particles and flexibly adapt to different polishing requirements, thereby improving surface quality. Therefore, the method has a high polishing rate on the substrate to be polished, and the resulting polished substrate has superior surface quality.

[0011] To achieve this objective, the present invention adopts the following technical solution:

[0012] In a first aspect, the present invention provides a method for abrasive-free CMP, the method comprising:

[0013] The polishing slurry is electrolytically activated when it is sprayed out.

[0014] And / or,

[0015] An anodic current is applied to the substrate to be polished, causing the surface of the substrate to be polished to oxidize.

[0016] In the abrasive-free CMP method provided by the present invention, the polishing slurry is electrolytically activated when it is sprayed out, which promotes the production of more active groups (such as hydroxyl groups) in the polishing slurry. The increase of hydroxyl groups will accelerate the oxidation reaction, thereby significantly improving the removal efficiency of the surface layer (such as the electroplating layer of the electroplating substrate) on the substrate to be polished (such as the electroplating substrate) and improving the surface quality after polishing.

[0017] In the abrasive-free CMP method provided by the present invention, an anodic current is applied to the substrate to be polished, and a current loop with the substrate to be polished (such as an electroplated substrate) as the anode is formed during the polishing process. This causes the surface layer of the substrate to be polished to undergo electrochemical oxidation while being chemically corroded, thereby synergistically enhancing the polishing efficiency of the surface layer (such as the electroplated layer of an electroplated substrate) and improving the surface quality after polishing.

[0018] In the abrasive-free CMP method provided by the present invention, different polishing requirements can be adapted by adjusting the voltage during the electrolytic activation process and / or adjusting the anodic current applied to the substrate to be polished.

[0019] The abrasive-free CMP method provided by this invention eliminates the need for preheating of the substrate to be polished or for further processing after polishing, thus obtaining a substrate with high surface quality.

[0020] In summary, the abrasive-free CMP method provided by this invention generates active groups through electrolytic activation of the polishing slurry and / or electrochemical oxidation induced by the application of anodic current, achieving a synergistic effect of mechanical grinding, chemical corrosion, and electrochemical reaction. It can efficiently remove the surface layer of the substrate without the intervention of abrasive particles and flexibly adapt to different polishing requirements, thereby improving surface quality. Therefore, the method has a high polishing rate on the substrate to be polished, and the polished substrate has superior surface quality.

[0021] Preferably, the electrolytic activation includes: during polishing, applying a first voltage between an inert cathode and an inert anode extending from the nozzle of the CMP device, so that the polishing liquid sprayed from the nozzle undergoes an electrochemical activation reaction.

[0022] In this invention, when the polishing liquid is sprayed from the nozzle, the polishing liquid immediately after being sprayed is located between the inert cathode and the inert anode extending from the nozzle. The polishing liquid, the inert cathode, the inert anode and the external DC power supply form a circuit, and the polishing liquid undergoes an electrochemical activation reaction.

[0023] Preferably, the first voltage is a DC voltage, and the first voltage is not higher than 60V. For example, it can be 10V, 15V, 20V, 25V, 30V, 35V, 40V, 45V, 50V, 55V or 60V, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0024] Preferably, the first voltage is a DC voltage, which is 20V to 40V. For example, it can be 20V, 22V, 24V, 26V, 28V, 30V, 32V, 34V, 36V, 38V or 40V, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0025] Preferably, the application of the anodic current includes: during polishing, applying a second voltage between the polishing head and the polishing pad of the CMP device to generate an anodic current on the substrate to be polished connected to the polishing head, causing an electrolytic reaction and oxidation of the surface of the substrate to be polished;

[0026] In this invention, during polishing, a path is formed between the substrate to be polished, the polishing head, the external DC power supply, and the polishing pad, thereby forming a current loop with the substrate to be polished as the anode. This causes the surface of the substrate to be polished to undergo electrochemical oxidation while being chemically corroded, thus synergistically enhancing the polishing efficiency of the substrate surface.

[0027] Preferably, the second voltage is a DC voltage, and the second voltage is not higher than 120V. For example, it can be 50V, 60V, 70V, 80V, 90V, 100V, 110V or 120V, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0028] Preferably, the second voltage is a DC voltage, and the second voltage is 50V~70V, for example, it can be 50V, 52V, 54V, 56V, 58V, 60V, 62V, 64V, 66V, 68V or 70V, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0029] Preferably, the polishing solution comprises an oxidant, a pH adjuster, a corrosion inhibitor, a complexing agent, and a solvent.

[0030] Preferably, the oxidant includes any one or a combination of at least two of hydrogen peroxide, ammonium persulfate, or periodic acid. Typical but non-limiting combinations include the combination of hydrogen peroxide and ammonium persulfate, the combination of ammonium persulfate and periodic acid, the combination of hydrogen peroxide and periodic acid, or the combination of hydrogen peroxide, ammonium persulfate, and periodic acid.

[0031] Preferably, the pH adjuster comprises any one or a combination of at least two of sulfuric acid, hydrochloric acid, or nitric acid. Typical but non-limiting combinations include combinations of sulfuric acid and hydrochloric acid, hydrochloric acid and nitric acid, sulfuric acid and nitric acid, or sulfuric acid, hydrochloric acid, and nitric acid.

[0032] Preferably, the corrosion inhibitor comprises any one or a combination of at least two of benzotriazole, methylbenzotriazole, or 2-mercaptobenzimidazole. Typical but non-limiting combinations include a combination of benzotriazole and methylbenzotriazole, a combination of methylbenzotriazole and 2-mercaptobenzimidazole, a combination of benzotriazole and 2-mercaptobenzimidazole, or a combination of benzotriazole, methylbenzotriazole, and 2-mercaptobenzimidazole.

[0033] Preferably, the complexing agent comprises any one or a combination of at least two of citric acid, ethylenediaminetetraacetic acid (EDTA), or oxalic acid. Typical but non-limiting combinations include combinations of citric acid and EDTA, combinations of EDTA and oxalic acid, combinations of citric acid and oxalic acid, or combinations of citric acid, EDTA, and oxalic acid.

[0034] Preferably, the solvent includes any one or a combination of at least two of water, ethanol, ethylene glycol, or propylene glycol. Typical but non-limiting combinations include combinations of water and ethanol, ethylene glycol and propylene glycol, ethanol and ethylene glycol, or water, ethanol, and propylene glycol.

[0035] Preferably, the concentration of the oxidant in the polishing solution is 1wt% to 5wt%, for example, it can be 1wt%, 1.5wt%, 2wt%, 2.5wt%, 3wt%, 3.5wt%, 4wt%, 4.5wt% or 5wt%, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0036] Preferably, the concentration of the pH adjuster in the polishing solution is 3wt% to 8wt%, for example, it can be 3wt%, 3.5wt%, 4wt%, 4.5wt%, 5wt%, 5.5wt%, 6wt%, 6.5wt%, 7wt%, 7.5wt% or 8wt%, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0037] Preferably, the concentration of the corrosion inhibitor in the polishing solution is 0.05wt% to 0.2wt%, for example, it can be 0.05wt%, 0.06wt%, 0.07wt%, 0.08wt%, 0.09wt%, 0.10wt%, 0.12wt%, 0.15wt%, 0.18wt%, or 0.20wt%, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0038] Preferably, the concentration of the complexing agent in the polishing solution is 0.005 mol / L to 0.02 mol / L, for example, it can be 0.005 mol / L, 0.006 mol / L, 0.007 mol / L, 0.008 mol / L, 0.009 mol / L, 0.010 mol / L, 0.012 mol / L, 0.015 mol / L, 0.018 mol / L or 0.020 mol / L, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0039] Preferably, in the method, the polishing head and the polishing table rotate independently from 60 rpm to 100 rpm, for example, 60 rpm, 65 rpm, 70 rpm, 75 rpm, 80 rpm, 85 rpm, 90 rpm, 95 rpm or 100 rpm, but are not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0040] Preferably, in the method, the downward pressure of the polishing head is 20kPa to 40kPa, for example, it can be 20kPa, 22kPa, 24kPa, 26kPa, 28kPa, 30kPa, 32kPa, 34kPa, 36kPa, 38kPa or 40kPa, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0041] Preferably, in the method, the flow rate of the polishing fluid is 60 mL / min to 150 mL / min, for example, it can be 60 mL / min, 70 mL / min, 80 mL / min, 90 mL / min, 100 mL / min, 110 mL / min, 120 mL / min, 130 mL / min, 140 mL / min or 150 mL / min, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0042] Preferably, in the method, the polishing time of the substrate to be polished is 5 min to 60 min, for example, it can be 5 min, 10 min, 15 min, 20 min, 25 min, 30 min, 35 min, 40 min, 45 min, 50 min, 55 min or 60 min, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0043] In a second aspect, the present invention provides a non-abrasive CMP device that matches the method described in the first aspect. The nozzle of the non-abrasive CMP device is provided with an inert cathode and an inert anode, and the inert cathode and inert anode are respectively connected to the negative and positive terminals of a first power supply.

[0044] And / or,

[0045] The polishing head and polishing pad of the abrasiveless CMP device are respectively connected to the positive and negative terminals of the second power supply.

[0046] In a second aspect, the present invention provides a polished substrate, which is obtained by the method described in the first aspect.

[0047] The numerical range described in this invention includes not only the point values ​​listed above, but also any point values ​​within the numerical ranges not listed above. Due to space limitations and for the sake of brevity, this invention will not exhaustively list all the specific point values ​​included in the range.

[0048] Compared with the prior art, the present invention has the following beneficial effects:

[0049] (1) In the abrasive-free CMP method provided by the present invention, the polishing liquid is electrolytically activated when it is sprayed out, which promotes the polishing liquid to generate more active groups, thereby significantly improving the removal efficiency of the surface layer (such as the electroplating layer of the electroplating substrate) on the substrate to be polished (such as the electroplating substrate) and improving the surface quality after polishing.

[0050] (2) In the abrasive-free CMP method provided by the present invention, an anodic current is applied to the substrate to be polished, and a current loop with the substrate to be polished (such as an electroplated substrate) as the anode is formed during the polishing process. This causes the surface layer of the substrate to be polished to undergo electrochemical oxidation while being chemically corroded, thereby synergistically enhancing the polishing efficiency of the surface layer (such as the electroplated layer of the electroplated substrate) and improving the surface quality after polishing.

[0051] (3) In the abrasive-free CMP method provided by the present invention, different polishing requirements can be adapted by adjusting the voltage during the electrolytic activation process and / or adjusting the anodic current applied to the substrate to be polished;

[0052] (4) In the abrasive-free CMP method provided by the present invention, it is not necessary to heat-treat the substrate to be polished in advance or to perform further processing after polishing, so as to obtain a substrate with high surface quality.

[0053] (5) The abrasive-free CMP method provided by the present invention generates active groups by electrolyzing the polishing liquid and / or applying an anodic current to induce electrochemical oxidation, thereby achieving the synergy of mechanical grinding, chemical corrosion and electrochemical reaction. Without the intervention of abrasive particles, the surface layer of the substrate can be efficiently removed and can flexibly adapt to different polishing requirements to improve surface quality. Therefore, the method has a high polishing rate on the substrate to be polished and the polished substrate has a better surface quality. Attached Figure Description

[0054] Figure 1 These are schematic diagrams of the abrasive-free CMP devices provided in Examples 1-3.

[0055] Figure 2 This is a schematic diagram of the abrasive-free CMP device provided in Example 4.

[0056] Figure 3 This is a schematic diagram of the abrasive-free CMP device provided in Example 5.

[0057] Wherein, 1-first power source; 2-nozzle; 3-inert cathode; 4-inert anode; 5-polishing slurry; 6-polishing disc; 7-polishing pad; 8-second power source; 9-polishing head; 10-first electrode; 11-second electrode; 12-substrate to be polished. Detailed Implementation

[0058] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention in any way.

[0059] The "range" disclosed in this invention can be defined in the form of a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, which define the boundaries of the specific range. This type of range definition can include or exclude endpoints; any endpoint can be independently included or excluded, and they can be arbitrarily combined, meaning any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60~120 and 80~110 are listed for specific parameters, it is understood that ranges of 60~110 and 80~120 are also expected. Furthermore, if minimum range values ​​1 and 2 are listed, and maximum range values ​​3, 4, and 5 are also listed, then the following ranges are all expected: 1~3, 1~4, 1~5, 2~3, 2~4, and 2~5. In this invention, unless otherwise stated, the numerical range "a~b" represents a shortened representation of any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range "0~5" indicates that all real numbers between "0" and "5" have been listed in this article; "0~5" is simply a shortened representation of these numerical combinations. Furthermore, when a parameter is described as an integer ≥2, it is equivalent to listing integers such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc. For instance, when a parameter is described as an integer selected from "2~10", it is equivalent to listing the integers 2, 3, 4, 5, 6, 7, 8, 9, and 10.

[0060] In this invention, "a combination of at least two" refers to a quantity greater than or equal to two, unless otherwise specified. For example, "any combination of one or at least two" means one or more or more items. It can be understood that when referring to "a combination of at least two," it refers to any suitable combination of multiple items, that is, a combination of "at least two" items carried out in a manner that does not conflict with and enables the implementation of this invention.

[0061] Unless otherwise specified, all embodiments and optional embodiments of the present invention can be combined with each other to form new technical solutions.

[0062] The term "embodiment" as used in this invention means that a specific feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment or implementation of the invention. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a mutually exclusive, independent, or alternative embodiment. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described in this invention can be combined with other embodiments.

[0063] In this invention, open-ended technical features or solutions described using terms such as "comprising" do not exclude additional members beyond those listed unless otherwise specified. They can be considered as providing both closed-ended features or solutions comprised of the listed members and open-ended features or solutions that include additional members beyond the listed members. For example, A includes a1, a2, and a3. Unless otherwise specified, it may also include other members or exclude additional members. This can be considered as providing both technical features or solutions where "A is composed of a1, a2, and a3" or "A is selected from a1, a2, and a3," and technical features or solutions where "A includes not only a1, a2, and a3, but also other members."

[0064] In this invention, unless otherwise specified, the features or solutions corresponding to "and / or" include any one of two or more of the related listed items, as well as any and all combinations of the related listed items. These arbitrary and all combinations include any two related listed items, any more related listed items, or a combination of all related listed items. For example, "A and / or B" represents a group consisting of A, B, and "a combination of A and B". "Containing A and / or B" can mean "containing A, containing B, and containing A and B", or "containing A, containing B, or containing A and B", and can be appropriately understood according to the context.

[0065] In this invention, the terms "first aspect," "second aspect," "third aspect," "fourth aspect," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or quantity, nor should they be construed as implicitly indicating the importance or quantity of the indicated technical features. Moreover, "first," "second," "third," "fourth," etc., serve only as a non-exhaustive enumeration and should be understood not to constitute a closed limitation on the quantity.

[0066] Example 1

[0067] This embodiment provides a method for abrasive-free CMP, the method comprising:

[0068] like Figure 1As shown, during polishing, a 30V DC voltage is applied through the first power source 1 between the inert cathode 3 and the inert anode 4 extending from the nozzle 2 of the abrasiveless CMP device, causing the polishing liquid 5 sprayed from the nozzle 2 to undergo an electrochemical activation reaction (the polishing liquid 5 undergoes an electrochemical activation reaction when it is between the inert cathode 3 and the inert anode 4, but the polishing liquid 5 is not shown between the inert cathode 3 and the inert anode 4 in the figure; only the surface of the polishing pad 7 on the polishing disc 6 after the polishing liquid 5 is sprayed out is shown).

[0069] During polishing, a 60V DC voltage is applied between the polishing head 9 and the polishing pad 7 of the abrasiveless CMP device via the second power supply 8 (the positive terminal of the second power supply 8 is electrically connected to the first electrode 10 connected to the polishing head 9, and the negative terminal of the second power supply 8 is electrically connected to the second electrode 11 connected to the polishing disc 6), so that an anodic current is generated on the substrate 12 to be polished connected to the polishing head 9, and an electrolytic reaction occurs, causing the surface of the substrate 12 to be polished to be oxidized.

[0070] The polishing solution 5 comprises an oxidant (hydrogen peroxide) with a mass concentration of 3 wt%, a pH adjuster (sulfuric acid) with a mass concentration of 5 wt%, a corrosion inhibitor (benzotriazole) with a mass concentration of 0.1 wt%, a complexing agent (citric acid) with a molar concentration of 0.01 mol / L, and a solvent (water).

[0071] In the method, the polishing head 9 and the polishing table rotate independently at 80 rpm, the downward pressure of the polishing head 9 is 30 kPa, the flow rate of the polishing liquid 5 is 100 mL / min, and the polishing time of the substrate 12 to be polished is 10 min.

[0072] This embodiment also provides a method that matches the above method, such as... Figure 1 The abrasive-free CMP apparatus shown has an inert cathode 3 and an inert anode 4 extending out of the nozzle 2. The inert cathode 3 and the inert anode 4 are respectively connected to the negative and positive terminals of the first power supply 1.

[0073] Furthermore, the polishing head 9 of the abrasive-free CMP device is electrically connected to the positive terminal of the second power supply 8 through the first electrode 10, and the polishing pad 7 of the abrasive-free CMP device is connected to the negative terminal of the second power supply 8 through the second electrode 11.

[0074] Example 2

[0075] This embodiment provides a method for abrasive-free CMP, the method comprising:

[0076] During polishing, a DC voltage of 20V is applied between the inert cathode 3 and the inert anode 4 extending from the nozzle 2 of the abrasiveless CMP device through the first power source 1, so that the polishing liquid 5 sprayed out of the nozzle 2 undergoes an electrochemical activation reaction.

[0077] During polishing, a 70V DC voltage is applied between the polishing head 9 and the polishing pad 7 of the abrasiveless CMP device through the second power supply 8 (the positive terminal of the second power supply 8 is electrically connected to the first electrode 10 connected to the polishing head 9, and the negative terminal of the second power supply 8 is electrically connected to the second electrode 11 connected to the polishing disk 6), so that an anodic current is generated on the substrate 12 to be polished connected to the polishing head 9, and an electrolytic reaction occurs, and the surface of the substrate 12 to be polished is oxidized.

[0078] The polishing solution 5 comprises an oxidant (ammonium persulfate) with a mass concentration of 1 wt%, a pH adjuster (sulfuric acid) with a mass concentration of 8 wt%, a corrosion inhibitor (methylbenzotriazole) with a mass concentration of 0.2 wt%, a complexing agent (ethylenediaminetetraacetic acid) with a molar concentration of 0.005 mol / L, and a solvent (water).

[0079] In the method, the polishing head 9 and the polishing table rotate independently at 100 rpm, the downward pressure of the polishing head 9 is 40 kPa, the flow rate of the polishing liquid 5 is 150 mL / min, and the polishing time of the substrate 12 to be polished is 10 min.

[0080] This embodiment also provides a non-abrasive CMP device that matches the above method. The non-abrasive CMP device is provided with an inert cathode 3 and an inert anode 4 extending out of the nozzle 2. The inert cathode 3 and the inert anode 4 are respectively connected to the negative and positive terminals of the first power supply 1.

[0081] Furthermore, the polishing head 9 of the abrasive-free CMP device is electrically connected to the positive terminal of the second power supply 8 through the first electrode 10, and the polishing pad 7 of the abrasive-free CMP device is connected to the negative terminal of the second power supply 8 through the second electrode 11.

[0082] Example 3

[0083] This embodiment provides a method for abrasive-free CMP, the method comprising:

[0084] During polishing, a DC voltage of 40V is applied between the inert cathode 3 and the inert anode 4 extending from the nozzle 2 of the abrasiveless CMP device through the first power source 1, so that the polishing liquid 5 sprayed out of the nozzle 2 undergoes an electrochemical activation reaction.

[0085] During polishing, a 50V DC voltage is applied between the polishing head 9 and the polishing pad 7 of the abrasiveless CMP device through the second power supply 8 (the positive terminal of the second power supply 8 is electrically connected to the first electrode 10 connected to the polishing head 9, and the negative terminal of the second power supply 8 is electrically connected to the second electrode 11 connected to the polishing disc 6), so that an anodic current is generated on the substrate 12 to be polished connected to the polishing head 9, and an electrolytic reaction occurs, and the surface of the substrate 12 to be polished is oxidized.

[0086] The polishing solution 5 comprises an oxidant (hydrogen peroxide) with a mass concentration of 5 wt%, a pH adjuster (hydrochloric acid) with a mass concentration of 3 wt%, a corrosion inhibitor (2-mercaptobenzimidazole) with a mass concentration of 0.05 wt%, a complexing agent (citric acid) with a molar concentration of 0.02 mol / L, and a solvent (water).

[0087] In the method, the polishing head 9 and the polishing table rotate independently at 60 rpm, the downward pressure of the polishing head 9 is 20 kPa, the flow rate of the polishing liquid 5 is 60 mL / min, and the polishing time of the substrate 12 to be polished is 10 min.

[0088] This embodiment also provides a non-abrasive CMP device that matches the above method. The non-abrasive CMP device is provided with an inert cathode 3 and an inert anode 4 extending out of the nozzle 2. The inert cathode 3 and the inert anode 4 are respectively connected to the negative and positive terminals of the first power supply 1.

[0089] Furthermore, the polishing head 9 of the abrasive-free CMP device is electrically connected to the positive terminal of the second power supply 8 through the first electrode 10, and the polishing pad 7 of the abrasive-free CMP device is connected to the negative terminal of the second power supply 8 through the second electrode 11.

[0090] Example 4

[0091] This embodiment provides a method for abrasive-free CMP, the method comprising:

[0092] like Figure 2 As shown, during polishing, a DC voltage of 30V is applied between the inert cathode 3 and the inert anode 4 extending from the nozzle 2 of the abrasiveless CMP device through the first power supply 1, so that the polishing liquid 5 sprayed out of the nozzle 2 undergoes an electrochemical activation reaction.

[0093] The polishing solution 5 comprises an oxidant (hydrogen peroxide) with a mass concentration of 3 wt%, a pH adjuster (sulfuric acid) with a mass concentration of 5 wt%, a corrosion inhibitor (benzotriazole) with a mass concentration of 0.1 wt%, a complexing agent (citric acid) with a molar concentration of 0.01 mol / L, and a solvent (water).

[0094] In the method, the polishing head 9 and the polishing table rotate independently at 80 rpm, the downward pressure of the polishing head 9 is 30 kPa, the flow rate of the polishing liquid 5 is 100 mL / min, and the polishing time of the substrate 12 to be polished is 10 min.

[0095] This embodiment also provides a method that matches the above method, such as... Figure 2 The abrasive-free CMP apparatus shown has an inert cathode 3 and an inert anode 4 extending from the nozzle 2. The inert cathode 3 and the inert anode 4 are respectively connected to the negative and positive terminals of the first power supply 1.

[0096] Example 5

[0097] This embodiment provides a method for abrasive-free CMP, the method comprising:

[0098] like Figure 3 As shown, during polishing, a 60V DC voltage is applied between the polishing head 9 and the polishing pad 7 of the abrasiveless CMP device through the second power supply 8 (the positive terminal of the second power supply 8 is electrically connected to the first electrode 10 connected to the polishing head 9, and the negative terminal of the second power supply 8 is electrically connected to the second electrode 11 connected to the polishing disk 6), so that an anodic current is generated on the substrate 12 to be polished connected to the polishing head 9, and an electrolytic reaction occurs, and the surface of the substrate 12 to be polished is oxidized.

[0099] The polishing solution 5 comprises an oxidant (hydrogen peroxide) with a mass concentration of 3 wt%, a pH adjuster (sulfuric acid) with a mass concentration of 5 wt%, a corrosion inhibitor (benzotriazole) with a mass concentration of 0.1 wt%, a complexing agent (citric acid) with a molar concentration of 0.01 mol / L, and a solvent (water).

[0100] In the method, the polishing head 9 and the polishing table rotate independently at 80 rpm, the downward pressure of the polishing head 9 is 30 kPa, the flow rate of the polishing liquid 5 is 100 mL / min, and the polishing time of the substrate 12 to be polished is 10 min.

[0101] This embodiment also provides a method that matches the above method, such as... Figure 3 The abrasive-free CMP apparatus shown has a polishing head 9 electrically connected to the positive terminal of a second power supply 8 via a first electrode 10, and a polishing pad 7 connected to the negative terminal of a second power supply 8 via a second electrode 11.

[0102] Example 6

[0103] This embodiment provides a method for abrasive-free CMP. Except that, during polishing, a DC voltage of 10V is applied between the inert cathode 3 and the inert anode 4 extending from the nozzle 2 of the abrasive-free CMP device, the rest is the same as in embodiment 4.

[0104] Example 7

[0105] This embodiment provides a method for abrasive-free CMP. Except that, during polishing, a DC voltage of 60V is applied between the inert cathode 3 and the inert anode 4 extending from the nozzle 2 of the abrasive-free CMP device, the rest is the same as in embodiment 4.

[0106] Example 8

[0107] This embodiment provides a method for abrasive-free CMP. Except that, during polishing, a DC voltage of 70V is applied between the inert cathode 3 and the inert anode 4 extending from the nozzle 2 of the abrasive-free CMP device, the rest is the same as in embodiment 4.

[0108] Example 9

[0109] This embodiment provides a method for abrasive-free CMP. Except that, during polishing, a DC voltage of 30V is applied between the polishing head 9 and the polishing pad 7 of the abrasive-free CMP device, the rest of the method is the same as in embodiment 5.

[0110] Example 10

[0111] This embodiment provides a method for abrasive-free CMP. Except that, during polishing, a DC voltage of 120V is applied between the polishing head 9 and the polishing pad 7 of the abrasive-free CMP device, the rest of the method is the same as in Embodiment 5.

[0112] Example 11

[0113] This embodiment provides a method for abrasive-free CMP. Except that, during polishing, a DC voltage of 150V is applied between the polishing head 9 and the polishing pad 7 of the abrasive-free CMP device, the rest of the method is the same as in Embodiment 5.

[0114] Comparative Example 1

[0115] This comparative example provides a method for abrasive-free CMP, except that the following are omitted: "During polishing, a 30V DC voltage is applied between the inert cathode 3 and the inert anode 4 extending from the nozzle 2 of the abrasive-free CMP device, causing the polishing liquid 5 sprayed from the nozzle 2 to undergo an electrochemical activation reaction," and "During polishing, a 60V DC voltage is applied between the polishing head 9 and the polishing pad 7 of the abrasive-free CMP device, causing an anodic current to be generated on the substrate 12 to be polished connected to the polishing head 9, resulting in an electrolytic reaction and oxidation of the surface of the substrate 12 to be polished." The rest of the method is the same as in Example 1.

[0116] Comparative Example 2

[0117] This comparative example provides a non-abrasive CMP method, which is the same as Comparative Example 1 except that the polishing slurry 5 also contains 2wt% nano-silica (i.e., the polishing slurry 5 also contains abrasive).

[0118] Using the abrasive-free CMP method and corresponding abrasive-free CMP apparatus provided in the above embodiments and comparative examples, the substrate 12 to be polished with a copper electroplated layer on the surface was polished. The material (copper electroplated layer) removal rate during the polishing process is shown in Table 1, and the surface roughness of the substrate after polishing is shown in Table 1.

[0119] Table 1

[0120]

[0121] From Table 1, we can obtain:

[0122] (1) Polishing was performed using the abrasive-free CMP method provided in Examples 1 to 3. The material removal rate was high (removal rate was 585.7 nm / min to 601.9 nm / min), and the surface roughness of the polished substrate was low (surface roughness was 4.2 nm to 4.5 nm), showing high polishing quality.

[0123] (2) By comparing Example 1 with Examples 4 and 5, it can be seen that in this invention, while the polishing liquid 5 is electrolyzed and activated when it is sprayed out, an anodic current is also applied to the substrate 12 to be polished, so that the surface of the substrate 12 to be polished is oxidized, which is more conducive to improving the polishing rate and surface quality. This is because the strong oxidizing active groups (such as hydroxyl radicals) generated by electrolysis activation can greatly enhance the chemical oxidation ability of the polishing liquid 5, while the application of anodic current directly promotes the rapid oxidation of the surface of the substrate 12 to be polished. The synergistic effect of the two makes the surface oxidation rate significantly faster, ensuring that the oxide layer generation rate and the mechanical removal rate reach the best balance, thereby obtaining a very high removal rate while ensuring the surface quality through uniform oxidation.

[0124] (3) By comparing Example 4 with Examples 6 and 7, it can be seen that in the present invention, when the voltage applied between the inert cathode 3 and the inert anode 4 extending from the nozzle 2 of the abrasive-free CMP device is 20V~40V during polishing, it is more conducive to improving the polishing effect. This is because when the applied voltage is within this range, it is conducive to efficiently generating a high concentration of active groups, thereby ensuring sufficient chemical oxidation efficiency on the substrate surface.

[0125] (4) By comparing Example 4 and Example 8, it can be seen that in the present invention, when the voltage applied between the inert cathode 3 and the inert anode 4 extending from the nozzle 2 of the abrasive-free CMP device is not higher than 60V during polishing, it is more conducive to improving the polishing effect. If the voltage is too high, the electrolytic reaction will be too violent and accompanied by the precipitation of a large number of bubbles. This will not only cause the flow field of the polishing liquid 5 to be unstable and affect the uniformity of polishing, but also easily cause micro-cavitation or pitting due to bubble rupture, increasing the surface roughness. In addition, the excessively high voltage will also cause side reactions, consume the effective components in the polishing liquid 5, and reduce the service life of the polishing liquid 5.

[0126] (5) By comparing Example 5 with Examples 9 and 10, it can be seen that in the present invention, when the voltage applied between the polishing head 9 and the polishing pad 7 of the abrasiveless CMP device is 50V~70V, it is more conducive to improving the polishing effect. This is because the voltage range can maintain the appropriate anodic polarization state on the surface of the substrate 12 to be polished, thereby improving the material removal rate and the surface quality of the substrate after polishing.

[0127] (6) By comparing Example 5 and Example 11, it can be seen that in the present invention, when the voltage applied between the polishing head 9 and the polishing pad 7 of the abrasiveless CMP device is not higher than 120V, it is more conducive to improving the polishing effect; if the applied voltage is too high and the anodic current density is too large, it is very easy to cause severe over-corrosion, pitting or grain boundary corrosion on the substrate surface, resulting in pits on the surface of the substrate after polishing.

[0128] (7) When polishing with the method provided in Example 1, the material removal rate is 226.9 nm / min, and the surface roughness of the polished substrate is 4.9 nm; when polishing with the method provided in Example 2, the material removal rate is 350.3 nm / min, and the surface roughness of the polished substrate is 8.1 nm.

[0129] By comparing Example 1 with Comparative Examples 1 and 2, it can be seen that in the abrasive-free CMP method provided by the present invention, the polishing slurry 5 is electrolytically activated when it is sprayed out, which promotes the polishing slurry 5 to generate more active groups, thereby significantly improving the removal efficiency of the upper surface layer (such as the electroplating layer of the electroplating substrate) of the substrate 12 to be polished (such as the electroplating substrate) and improving the surface quality after polishing.

[0130] In the abrasive-free CMP method provided by the present invention, an anodic current is applied to the substrate 12 to be polished, and a current loop with the substrate 12 to be polished (such as an electroplated substrate) as the anode is formed during the polishing process. This causes the surface layer of the substrate 12 to be polished to undergo electrochemical oxidation while being chemically corroded, thereby synergistically enhancing the polishing efficiency of the surface layer (such as the electroplated layer of an electroplated substrate) and improving the surface quality after polishing.

[0131] In the abrasive-free CMP method provided by the present invention, different polishing requirements can be adapted by adjusting the voltage during the electrolytic activation process and / or adjusting the anodic current applied to the substrate 12 to be polished.

[0132] In the abrasive-free CMP method provided by the present invention, a substrate with high surface quality can be obtained without preheating the substrate 12 to be polished or further processing after polishing.

[0133] In summary, the abrasive-free CMP method provided by this invention generates active groups through electrolytic activation of the polishing slurry 5 and / or electrochemical oxidation induced by the application of anodic current, achieving synergy between mechanical grinding, chemical corrosion, and electrochemical reaction. It can efficiently remove the surface layer of the substrate without the intervention of abrasive particles and flexibly adapt to different polishing requirements, thereby improving surface quality. Therefore, the method has a high polishing rate on the substrate 12 to be polished, and the polished substrate has superior surface quality.

[0134] The applicant declares that the above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A method for abrasive-free CMP, characterized in that, The method includes: The polishing slurry is electrolytically activated when it is sprayed out. And / or, An anodic current is applied to the substrate to be polished, causing the surface of the substrate to be polished to oxidize.

2. The method according to claim 1, characterized in that, The electrolytic activation includes: during polishing, applying a first voltage between an inert cathode and an inert anode extending from the nozzle of the abrasive-free CMP device, thereby causing the polishing liquid ejected from the nozzle to undergo an electrochemical activation reaction.

3. The method according to claim 2, characterized in that, The first voltage is a DC voltage, and the first voltage is not higher than 60V.

4. The method according to claim 2, characterized in that, The first voltage is a DC voltage, and the first voltage is 20V~40V.

5. The method according to claim 1, characterized in that, The application of the anodic current includes: during polishing, applying a second voltage between the polishing head and the polishing pad of the abrasiveless CMP device, so that an anodic current is generated on the substrate to be polished connected to the polishing head, an electrolytic reaction occurs, and the surface of the substrate to be polished is oxidized.

6. The method according to claim 5, characterized in that, The second voltage is a DC voltage, and the second voltage is 50V~70V.

7. The method according to any one of claims 1 to 6, characterized in that, The polishing fluid comprises an oxidant, a pH adjuster, a corrosion inhibitor, a complexing agent, and a solvent.

8. The method according to claim 7, characterized in that, The oxidant includes any one or a combination of at least two of hydrogen peroxide, ammonium persulfate, or periodic acid; And / or, the pH adjuster includes any one or a combination of at least two of sulfuric acid, hydrochloric acid, or nitric acid; And / or, the corrosion inhibitor comprises any one or a combination of at least two of benzotriazole, methylbenzotriazole or 2-mercaptobenzimidazole; And / or, the complexing agent includes any one or a combination of at least two of citric acid, ethylenediaminetetraacetic acid, or oxalic acid; And / or, the solvent includes any one or a combination of at least two of water, ethanol, ethylene glycol or propylene glycol; And / or, the concentration of the oxidant in the polishing solution is 1wt%~5wt%; And / or, the concentration of the pH adjuster in the polishing solution is 3wt%~8wt%; And / or, the concentration of the corrosion inhibitor in the polishing solution is 0.05wt%~0.2wt%; And / or, the concentration of the complexing agent in the polishing solution is 0.005 mol / L to 0.02 mol / L.

9. A non-abrasive CMP apparatus compatible with the method of any one of claims 1 to 8, characterized in that, The abrasive-free CMP device is provided with an inert cathode and an inert anode extending out of the nozzle, and the inert cathode and inert anode are respectively connected to the negative and positive terminals of the first power supply. And / or, The polishing head and polishing pad of the abrasiveless CMP device are respectively connected to the positive and negative terminals of the second power supply.

10. A polished substrate, characterized in that, The polished substrate is obtained by the method described in any one of claims 1 to 8.

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