Method for forming tungsten plug in carbon-based integrated circuit and carbon-based integrated circuit
By forming a barrier layer between titanium nitride and palladium on the carbon-based integrated circuit, and removing the tungsten layer through chemical mechanical grinding, the problem of uneven surface of the tungsten plug is solved, and a high-precision planarized tungsten plug is achieved, meeting the device performance requirements of carbon-based integrated circuits.
Patent Information
- Application Number
- CN202510269528.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-03-07
- Publication Date
- 2025-07-01
AI Technical Summary
In the existing silicon-based integrated circuit manufacturing process, there are problems such as tooth thickness of tungsten film and uneven surface during the formation of tungsten plugs, which is difficult to meet the device performance requirements of carbon-based integrated circuits.
Connecting holes are formed on the oxide layer of the carbon-based integrated circuit, and a barrier layer of titanium nitride and palladium are deposited on its surface, followed by depositing a tungsten layer, and the tungsten layer on the barrier layer and the barrier layer on the oxide layer are removed by chemical mechanical grinding, retaining the tungsten layer in the connection hole to form a high-precision planarized tungsten plug.
It realizes the formation of high-precision and flat tungsten plugs on carbon-based integrated circuits, solves the surface defects and recesses of tungsten plugs, and meets the device performance requirements of carbon-based integrated circuits.
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Figure CN120237093A_ABST
Abstract
Description
Technical Field
[0001] The present disclosure relates to a method for forming a tungsten plug in a carbon-based integrated circuit and a carbon-based integrated circuit. Background Art
[0002] In the existing silicon-based integrated circuit manufacturing process, titanium and titanium nitride are deposited on an oxide layer, and then tungsten is deposited. The tungsten fills the connection holes in the oxide layer and covers the entire surface of the oxide layer, and a titanium and titanium nitride layer is between the tungsten and the oxide layer. The tungsten completely fills the holes and forms an overly thick tungsten film on the surface, for example Figure 11 as shown. Then, the surface is polished by chemical mechanical polishing (CMP) to remove the tungsten, titanium, and titanium nitride on the surface of the oxide layer, and the tungsten, titanium, and titanium nitride in the connection holes are retained. Finally, a flat tungsten plug is formed, for example Figure 12 as shown. Summary of the Invention
[0003] According to one aspect of the present disclosure, a method for forming a tungsten plug in a carbon-based integrated circuit is provided, including: forming connection holes on a first surface of an oxide layer of a substrate; depositing a barrier layer on the first surface and the surface of the connection holes, where the barrier layer is a combination of titanium nitride and palladium, or a combination of titanium nitride and scandium; depositing a tungsten filling layer on the barrier layer; and removing the tungsten layer on the barrier layer and the barrier layer on the first surface by chemical mechanical polishing, and retaining the tungsten layer in the connection holes to form the tungsten plug.
[0004] According to the technical solution of this aspect, a method for forming a tungsten plug on a carbon-based integrated circuit is proposed for the first time, which can meet the requirements of the device performance of the carbon-based integrated circuit.
[0005] According to the method for forming a tungsten plug according to at least one embodiment of the present disclosure, in the barrier layer, the film layer formed by titanium nitride is the upper layer, and the film layer formed by palladium or scandium is the lower layer.
[0006] According to the method for forming a tungsten plug according to at least one embodiment of the present disclosure, removing the tungsten layer on the barrier layer and the barrier layer on the first surface by chemical mechanical polishing includes: using a tungsten polishing liquid to remove the tungsten layer and the barrier layer on the first surface through a polishing disk; and using an oxide polishing liquid to remove a part of the oxide on the first surface of the oxide layer through the polishing disk to repair the depression of the tungsten plug and the defects on the surface of the oxide layer.
[0007] According to the technical solution of this embodiment, it can form a tungsten plug with high-precision planarization and can process the surface defects of the oxide layer.
[0008] The tungsten plug formation method according to at least one embodiment of the present disclosure uses a tungsten grinding fluid to remove the tungsten layer and the barrier layer on the first surface through a polishing pad, and includes: using a first polishing pad to remove the tungsten layer; using a second polishing pad to remove the remaining tungsten and the barrier layer.
[0009] The tungsten plug formation method according to at least one embodiment of the present disclosure, using a first polishing pad to remove the tungsten layer, includes: polishing by a polishing time control method or an endpoint detection method to remove most of the tungsten.
[0010] The tungsten plug formation method according to at least one embodiment of the present disclosure, using a second polishing pad to remove the remaining tungsten and the barrier layer, includes: polishing by an endpoint detection method to remove the remaining tungsten, titanium nitride, and palladium or scandium, and polishing to the oxide layer.
[0011] The tungsten plug formation method according to at least one embodiment of the present disclosure, after polishing to the oxide layer, uses deionized water to continue polishing through the second polishing pad to remove the remaining tungsten grinding fluid and palladium or scandium particles on the surface.
[0012] The tungsten plug formation method according to at least one embodiment of the present disclosure, after polishing by an endpoint detection method and before using deionized water to continue polishing through the second polishing pad, includes: using a tungsten grinding fluid to perform over-polishing through the second polishing pad to remove the remaining palladium or scandium.
[0013] According to the technical solution of this embodiment, the removal of palladium or scandium is achieved, and the problem of the lack of a suitable grinding fluid for removing palladium or scandium is solved.
[0014] The tungsten plug formation method according to at least one embodiment of the present disclosure, when using an oxide grinding fluid to remove a part of the oxide on the first surface of the oxide layer through a polishing pad, the polishing pad used is a third polishing pad different from the first polishing pad and the second polishing pad.
[0015] The tungsten plug formation method according to at least one embodiment of the present disclosure, the hardness of the polishing pads of the first polishing pad and the second polishing pad is greater than the hardness of the polishing pad of the third polishing pad.
[0016] According to another aspect of the present disclosure, a carbon-based integrated circuit is provided. The carbon-based integrated circuit includes a tungsten plug structure. In the tungsten plug structure, the film layer formed of titanium nitride is the upper layer, and the film layer formed of palladium or scandium is the lower layer, wherein the upper layer contacts the tungsten in the tungsten plug structure, and the lower layer contacts the oxide layer.
[0017] According to the carbon-based integrated circuit of this aspect, the tungsten plug structure of the carbon-based integrated circuit is proposed for the first time, and this tungsten plug structure can meet the device performance requirements.
[0018] According to another aspect of the present disclosure, a carbon-based integrated circuit is provided, and the tungsten plug structure in the carbon-based integrated circuit is formed by the tungsten plug forming method described in any one of the above. BRIEF DESCRIPTION OF THE DRAWINGS
[0019] The drawings illustrate exemplary embodiments of the present disclosure and, together with the description thereof, are used to explain the principles of the present disclosure. These drawings are included to provide a further understanding of the present disclosure and are included in this specification and form a part of this specification.
[0020] Figure 1 is a flowchart of a method for forming a tungsten plug in a carbon-based integrated circuit according to an embodiment of the present disclosure.
[0021] Figure 2 shows a schematic diagram of a device structure before step S110.
[0022] Figure 3 shows a schematic diagram of a device structure after step S110.
[0023] Figure 4 shows a schematic diagram of a device structure after step S120.
[0024] Figure 5 shows a schematic diagram of a device structure after step S130.
[0025] Figure 6 shows a schematic diagram of a device structure after step S140.
[0026] Figure 7 is a flowchart of a method for forming a tungsten plug in a carbon-based integrated circuit according to an embodiment of the present disclosure.
[0027] Figure 8 shows a schematic diagram of a device structure in which a depression is formed in the tungsten plug.
[0028] Figure 9 shows a flowchart of chemical mechanical polishing according to an embodiment of the present disclosure.
[0029] Figure 10 shows the tungsten plug structure of a carbon-based integrated circuit according to an embodiment of the present disclosure Figure 11 and Figure 12 shows a schematic diagram of tungsten plug formation in the prior art. DETAILED DESCRIPTION
[0030] The present disclosure will be further described in detail below in conjunction with the accompanying drawings and embodiments. It can be understood that the specific embodiments described herein are only used to explain the relevant content and do not limit the present disclosure. Additionally, it should be noted that for the convenience of description, only the parts related to the present disclosure are shown in the drawings.
[0031] It should be noted that, without conflict, the embodiments in the present disclosure and the features in the embodiments can be combined with each other. The technical solutions of the present disclosure will be described in detail below with reference to the drawings and embodiments.
[0032] Unless otherwise specified, the exemplary embodiments / examples shown will be understood to provide exemplary features of various details of some ways in which the technical concept of the present disclosure can be implemented in practice. Therefore, unless otherwise specified, without departing from the technical concept of the present disclosure, the features of various embodiments / examples can be additionally combined, separated, interchanged, and / or rearranged.
[0033] In the drawings, cross - hatching and / or shading are generally used to make the boundaries between adjacent components clear. Thus, unless stated otherwise, the presence or absence of cross - hatching or shading does not convey or imply any preference or requirement for the specific material, material properties, dimensions, proportions, commonality between the components shown, and / or any other characteristics, attributes, properties, etc. of the components. Additionally, in the drawings, for clarity and / or descriptive purposes, the dimensions and relative dimensions of the components may be exaggerated. When the exemplary embodiments can be implemented differently, the specific process sequences can be performed in a different order than described. For example, two consecutively described processes can be performed substantially simultaneously or in an order opposite to the described order. Furthermore, the same reference numerals denote the same components.
[0034] In the current silicon - based integrated circuit manufacturing process, a tungsten plug (W Plug) structure is formed by chemical mechanical polishing. In the tungsten plug structure, the film layer between tungsten and the oxide layer is Ti (titanium) and TiN (titanium nitride). During the chemical mechanical polishing process, a tungsten polishing liquid is used to remove the surface tungsten layer, Ti layer, and TiN layer through a combination of chemical reaction and mechanical polishing to form a tungsten plug. In this process, the tungsten polishing liquid can react chemically with tungsten, Ti, and TiN to produce by - products that are easily removed, and then can be easily removed by mechanical action, and precise planarization can be achieved.
[0035] The inventors have found through research that in the manufacturing process of carbon - based integrated circuit transistors, the tungsten plugs of carbon - based integrated circuits need to be different from those of silicon - based integrated circuits. If they are the same, the requirements for the device performance of carbon - based integrated circuits will not be met.
[0036] Therefore, in the present application, through careful research, the inventors have pioneered a tungsten plug structure for carbon-based integrated circuits, which can well meet the requirements of the device performance of carbon-based integrated circuits. In this structure, a tungsten plug structure is formed on the oxide layer. In the tungsten plug structure, a film layer formed by titanium nitride and palladium (Pd), or a film layer formed by titanium nitride and scandium (Sc), is provided between the tungsten and the oxide layer. As a specific embodiment of the tungsten plug structure, palladium or scandium is in the lower layer, titanium nitride is in the upper layer, and tungsten is above the titanium nitride.
[0037] During the process of forming the tungsten plug structure of the carbon-based integrated circuit of the present application, it is necessary to remove the tungsten, titanium nitride, and palladium or scandium on the surface. However, there is currently no suitable abrasive for removing palladium or scandium, especially no suitable abrasive for removing palladium, and it is difficult for the tungsten abrasive to chemically react with palladium or scandium. Therefore, in the present application, in order to form the tungsten plug structure of the carbon-based integrated circuit, a method for forming this tungsten plug structure is further provided. The tungsten plug formed according to this forming method has high-precision flatness.
[0038] According to at least one embodiment of the present disclosure, a method for forming a tungsten plug in a carbon-based integrated circuit is provided. Figure 1 The flowchart of the method for forming a tungsten plug in a carbon-based integrated circuit according to an embodiment of the present disclosure is shown.
[0039] As Figure 1 shown, the method for forming the tungsten plug may include steps S110 to S140.
[0040] In step S110, a connection hole is formed on the first surface of the oxide layer of the substrate of the carbon nanotube integrated circuit.
[0041] Figure 2 The schematic diagram of the device structure before step S110 is shown. As Figure 2 shown, the reference numeral of the oxide layer of the substrate is 210, and the reference numeral of the first surface of the oxide layer is 211, where the first surface 211 is the surface for forming the tungsten plug. The oxide layer may be a silicon dioxide oxide layer or other suitable oxide layers.
[0042] Figure 3 The schematic diagram of the device structure after step S110 is shown. As Figure 3 shown, a connection hole 220 is formed on the first surface, and the wall surface of the connection hole 220 is called the surface 221 of the connection hole. During the etching process, reactive ion etching or plasma etching may be used. For the specific processing during the etching process, reference may be made to the prior art and will not be elaborated here.
[0043] In step S120, a barrier layer 230 is deposited on the first surface 211 and the surface 221 of the connection hole 220. In the present application, the barrier layer 230 is a combination of titanium nitride (TiN) and palladium (Pd), or a combination of titanium nitride and scandium (Sc). During the deposition of the barrier layer, a palladium layer or a scandium layer is first deposited, and then a titanium nitride layer is deposited on the palladium layer or the scandium layer. As an alternative embodiment, a titanium layer can also be first deposited on the oxide layer, a palladium layer or a scandium layer is deposited on the titanium layer, and a titanium nitride layer is deposited on the palladium layer or the scandium layer. In the present application, the example of depositing a palladium layer or a scandium layer first and then depositing a titanium nitride layer on the palladium layer or the scandium layer is used for illustration. Figure 4 A schematic diagram of the device after step S120 is shown.
[0044] In step S130, a tungsten filling layer 240 is deposited on the barrier layer 230. In a specific embodiment, a tungsten layer 240 is formed on the barrier layer 230 by chemical vapor deposition (CVD). As Figure 4 shown, the tungsten layer 240 is formed to cover the barrier layer 230, and the tungsten layer 240 fills the barrier layer on the first surface of the oxide layer and the surface in the connection hole 220 and covers the barrier layer in the connection hole 220. Figure 5 A schematic diagram of the device after step S130 is shown.
[0045] In step S140, the tungsten layer 240 on the barrier layer 230 and the barrier layer 230 on the first surface 211 are removed by chemical mechanical polishing, and the tungsten in the connection hole 220 is retained. The tungsten in the connection hole 220 forms a tungsten plug 250. In the connection hole 220, the barrier layer 230 is located between the tungsten plug 250 and the hole wall of the connection hole 220. Figure 6 A schematic diagram of the device after step S140 is shown.
[0046] According to a further embodiment of the present disclosure, as Figure 7 shown, step S140 may include step S1410 and step S1420.
[0047] In step S1410, using a tungsten polishing liquid, the tungsten layer and the barrier layer on the first surface are removed by a polishing disk. During the polishing process using the tungsten polishing liquid through chemical mechanical treatment in this step, a part of the tungsten in the connection hole 220 will be polished off. Figure 8 A schematic diagram of the device formed after step S1410 is shown. As Figure 8 shown, the tungsten plug in the connection hole 220 is formed with a depression.
[0048] In order to repair and reduce the depression, in step S1420, an oxide polishing liquid is used to remove a part of the oxide from the first surface of the oxide layer through a polishing pad. In step S1420, by removing a part of the oxide, the depression of the tungsten plug can be repaired and the surface defects of the oxide layer can also be repaired. For the schematic diagram of the device after step S1420, reference can be made to Figure 6 .
[0049] In step S1410, a tungsten polishing liquid can be used. Based on chemical mechanical processing, first, the tungsten layer is removed through the first polishing pad, and then the second polishing pad is used to remove the remaining tungsten and the barrier layer.
[0050] In the present disclosure, during the process of removing the tungsten layer through the first polishing pad, most of the tungsten can be removed by controlling the polishing time. The polishing time can be a preset time. The first polishing pad can be set at the first station and has a hard polishing pad. In addition, most of the tungsten can also be removed by performing polishing through an endpoint detection method. Here, the endpoint can be set as the barrier layer, that is, the polishing step stops when the barrier layer is polished to.
[0051] During the process of using the second polishing pad to remove the remaining tungsten and the barrier layer, a tungsten polishing liquid can be used, and a small amount of remaining tungsten, titanium nitride, and the underlying palladium are removed through the second polishing pad. The endpoint detection method can be adopted during this process, and the endpoint is the oxide layer. That is, by detecting the oxide layer, the polishing process stops on the oxide layer. The second polishing pad can be set at the second station, and the hardness of the second polishing pad of the second polishing pad is the same as that of the first polishing pad of the first polishing pad. During this process, since palladium is difficult to chemically react with the tungsten polishing liquid, the removal of palladium is achieved through the mechanical action between the polishing particles of the tungsten polishing liquid and palladium.
[0052] During the process of using the second polishing pad to perform polishing through the endpoint detection method, a part of palladium will still remain on the oxide layer. The reason is that the texture of metallic palladium is relatively soft and it is difficult to chemically react with the polishing liquid. Therefore, there will be random palladium residues on the surface of the oxide layer. At this time, the tungsten polishing liquid can continue to be used, and an over polish step is added to remove the remaining palladium through the second polishing pad. Here, it is still achieved through the mechanical action between the polishing particles of the tungsten polishing liquid and palladium.
[0053] According to a further embodiment of the present application, the following treatment can also be added: Deionized water is used to continue polishing through the second polishing pad. During this polishing process, the polishing pressure is relatively small, and its purpose is to remove the remaining polishing liquid and palladium particles on the surface of the oxide layer.
[0054] In the above description, residual palladium is removed through an over-grinding step and palladium particles are removed using deionized water. As another embodiment, the over-grinding step may not be added, and only deionized water is used to remove palladium particles.
[0055] Since palladium metal is difficult to remove and the grinding time needs to be increased, dishing will occur in the tungsten plug. And as described above, during the removal of palladium, mechanical action is relied on, so it will cause damage to the surface of the oxide layer. Therefore, step S1420 is added in this application. Through step S1420, the dishing of the tungsten plug and the surface defects of the oxide layer are repaired. The grinding disk used in step S1420 is the third grinding disk, the third grinding disk can be arranged at the third station, and the hardness of the grinding pad of the third grinding disk is less than the hardness of the grinding pads of the first grinding disk and the second grinding disk.
[0056] Figure 9 The flowchart of chemical mechanical polishing of the above embodiment is shown.
[0057] In step S910, a tungsten polishing liquid is used, and most of the tungsten is removed through the first grinding disk based on the grinding time control method or the endpoint detection method. In step S920, a tungsten polishing liquid is used, and the residual tungsten, titanium nitride, and a part of palladium are removed through the second grinding disk based on the endpoint detection method. In step S930, the tungsten polishing liquid is continuously used, and the residual palladium is removed through the second grinding disk based on the over-grinding step. In step S940, deionized water is used, and the residual tungsten polishing liquid and palladium particles on the surface of the oxide layer are removed through the second grinding disk. In this application, step S930 can be omitted, and the treatment is directly carried out through step S940. In step S950, an oxide polishing liquid is used, and polishing is carried out through the third grinding disk, so that a part of the oxide layer is ground off to repair the dishing of the tungsten plug and the defects on the surface of the oxide layer.
[0058] In addition, in the steps of using the second grinding disk, it is also feasible to use an independent grinding disk at an independent station for each step.
[0059] According to a further embodiment of the present disclosure, a carbon-based integrated circuit is also provided, wherein the carbon-based integrated circuit includes a tungsten plug structure. Figure 10 The tungsten plug structure of the carbon-based integrated circuit is shown, the film layer formed by titanium nitride is the upper layer, and the film layer formed by palladium or scandium is the lower layer, wherein the upper layer contacts the tungsten in the tungsten plug structure, and the lower layer contacts the oxide layer.
[0060] According to a further embodiment of the present disclosure, a carbon-based integrated circuit is also provided, wherein the tungsten plug structure in the carbon-based integrated circuit is formed by the tungsten plug forming method described above.
[0061] In the description of this specification, the description with reference to terms such as "one embodiment / way", "some embodiments / ways", "example", "specific example", or "some examples" means that the specific features, structures, materials, or characteristics described in connection with the embodiment / way or example are included in at least one embodiment / way or example of this application. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment / way or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in a suitable manner in any one or more embodiments / ways or examples. In addition, without contradiction, those skilled in the art can combine and combine the different embodiments / ways or examples described in this specification and the features of different embodiments / ways or examples.
[0062] In addition, the terms "first" and "second" are used only for descriptive purposes and cannot be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include at least one of such features. In the description of this application, "a plurality" means at least two, such as two, three, etc., unless otherwise specifically and clearly defined.
[0063] Those skilled in the art should understand that the above embodiments are only for clearly explaining the present disclosure and are not intended to limit the scope of the present disclosure. For those skilled in the art, other changes or modifications can be made on the basis of the above disclosure, and these changes or modifications are still within the scope of the present disclosure.
Claims
1. A method for forming a tungsten plug in a carbon-based integrated circuit, characterized in that: include: forming a connection hole on a first surface of the oxide layer of the substrate; Depositing a barrier layer on the first surface and the surface of the connection hole, wherein the barrier layer is a combination of titanium nitride and palladium, or a combination of titanium nitride and scandium; depositing a filling tungsten layer on the barrier layer; The tungsten layer on the barrier layer and the barrier layer on the first surface are removed by chemical mechanical polishing, and the tungsten layer in the connection hole is retained to form the tungsten plug.
2. The method for forming a tungsten plug according to claim 1, wherein: In the barrier layer, the film layer formed by the titanium nitride is an upper layer, and the film layer formed by the palladium or scandium is a lower layer.
3. The method for forming a tungsten plug according to claim 1 or 2, characterized in that: Removing the tungsten layer on the barrier layer and the barrier layer on the first surface by chemical mechanical polishing, comprising: Using a tungsten polishing liquid, removing the tungsten layer and the barrier layer on the first surface through a polishing disk; and An oxide polishing liquid is used to remove a portion of oxide on the first surface of the oxide layer through a polishing disk to repair the depression of the tungsten plug and the defects on the surface of the oxide layer.
4. The method for forming a tungsten plug according to claim 3, wherein: Using a tungsten polishing liquid to remove the tungsten layer and the barrier layer on the first surface through a polishing disk includes: removing the tungsten layer using a first grinding disk; A second grinding wheel is used to remove the remaining tungsten and the barrier layer.
5. The method for forming a tungsten plug according to claim 4, wherein: Optionally, removing the tungsten layer using a first grinding disk includes: performing grinding by grinding time control or endpoint detection to remove most of the tungsten, Optionally, using a second grinding disk to remove residual tungsten and the barrier layer includes: grinding by endpoint detection to remove residual tungsten, titanium nitride, and palladium or scandium, grinding to the oxide layer, Optionally, after grinding to the oxide layer, deionized water is used to continue grinding through a second grinding disk to remove residual tungsten grinding liquid and palladium or scandium particles on the surface.
6. The method for forming a tungsten plug according to claim 5, wherein: After grinding by the endpoint detection method and before continuing grinding by using the second grinding disc with deionized water, the method includes: using tungsten grinding liquid to perform grinding treatment by using the second grinding disc to remove residual palladium or scandium.
7. The method for forming a tungsten plug according to any one of claims 4 to 6, characterized in that: In the process of removing a portion of oxide from the first surface of the oxide layer by means of a grinding disk using an oxide grinding liquid, the grinding disk used is a third grinding disk different from the first grinding disk and the second grinding disk.
8. The method for forming a tungsten plug according to claim 7, wherein: The hardness of the grinding pads of the first grinding disk and the second grinding disk is greater than the hardness of the grinding pad of the third grinding disk.
9. A carbon-based integrated circuit, characterized in that: The carbon-based integrated circuit includes a tungsten plug structure, in which a film layer formed of titanium nitride is an upper layer, and a film layer formed of palladium or scandium is a lower layer, wherein the upper layer contacts the tungsten in the tungsten plug structure, and the lower layer contacts the oxide layer.
10. A carbon-based integrated circuit, characterized in that: The tungsten plug structure in the carbon-based integrated circuit is formed by the tungsten plug forming method according to any one of claims 1 to 8.