Chemical mechanical polishing process method and apparatus

Abstract

The embodiment of the present disclosure provides a chemical mechanical polishing process method and device, and relates to the technical field of semiconductor manufacturing, and comprises the following steps: providing a substrate formed with a dielectric layer and a conductive layer; using a mixed polishing liquid of a first polishing liquid and a second polishing liquid to perform chemical mechanical polishing on the substrate placed on a polishing disc, so as to remove the conductive layer covering the upper surface of the dielectric layer; after using a cleaning liquid to flush the substrate placed on the polishing disc, using the second polishing liquid to perform chemical mechanical polishing on the substrate placed on the polishing disc, so as to remove part of the dielectric layer, so that the upper surface of the dielectric layer is lower than the upper surface of the conductive layer filled in the groove, thereby ensuring that the conductive layer in the groove can protrude from the surface of the dielectric layer, and the product yield of the CMP process based on a single polishing disc is improved.

Description

TECHNICAL FIELD

[0001] Embodiments of the present disclosure relate to the technical field of semiconductor manufacturing, and in particular, to a chemical mechanical polishing process method and device. BACKGROUND

[0002] Chemical mechanical polishing (CMP) process is one of the most critical processes in semiconductor manufacturing process, which can be used for the preparation of conductive plug in semiconductor structure.

[0003] Taking the CMP process of metal tungsten as an example, in the preparation process of tungsten connection filling hole, a deep-well groove is generally formed in the oxide layer, and then metal tungsten is filled in the groove. In the filling process, the surface of the oxide layer is also deposited with metal tungsten. At this time, it is necessary to remove the metal tungsten on the surface of the oxide layer by the CMP process, and only the metal tungsten in the groove is retained as the metal connection. The existing CMP process generally uses two polishing discs. Although the metal tungsten in the groove can be protruded from the surface of the oxide layer by using different polishing liquids for the two polishing discs, the utilization rate of the CMP machine is not high.

[0004] In order to improve the utilization rate of the CMP machine, the CMP process based on a single polishing disc is proposed in the prior art. However, the CMP process based on a single polishing disc in the prior art cannot make the metal tungsten in the groove protrude from the surface of the oxide layer, which may result in that the metal tungsten and the metal conductive layer cannot be effectively connected, thereby reducing the product yield. SUMMARY

[0005] Embodiments of the present disclosure provide a chemical mechanical polishing process method and device, which can solve the technical problem of low product yield of the CMP process based on a single polishing disc in the prior art.

[0006] In a first aspect, embodiments of the present disclosure provide a chemical mechanical polishing process method, comprising:

[0007] providing a substrate formed with a dielectric layer and a conductive layer, the dielectric layer having a groove, the conductive layer covering the upper surface of the dielectric layer and filling in the groove, the conductive layer comprising a tungsten layer;

[0008] performing chemical mechanical polishing on the substrate placed on a polishing disc using a mixed polishing liquid of a first polishing liquid and a second polishing liquid, to remove the conductive layer covering the upper surface of the dielectric layer; the polishing rate of the mixed polishing liquid on the conductive layer is greater than the polishing rate on the dielectric layer;

[0009] performing flushing on the substrate placed on the polishing disc using a cleaning liquid, to remove the mixed polishing liquid remaining on the substrate;

[0010] chemically mechanically polishing the substrate placed on the polishing plate using the second polishing liquid to remove part of the dielectric layer so that the upper surface of the dielectric layer is lower than the upper surface of the conductive layer filled in the groove, the second polishing liquid having a smaller polishing rate on the conductive layer than on the dielectric layer.

[0011] In an embodiment, the conductive layer further comprises a titanium nitride layer, the titanium nitride layer being between the dielectric layer and the tungsten layer.

[0012] In an embodiment, the chemically mechanically polishing the substrate placed on the polishing plate using the mixed polishing liquid of the first polishing liquid and the second polishing liquid to remove the conductive layer covered by the upper surface of the dielectric layer comprises:

[0013] detecting whether the titanium nitride layer has been polished to using a preset chemical mechanical polishing endpoint detection program during the chemically mechanically polishing the substrate using the mixed polishing liquid.

[0014] stopping the chemically mechanically polishing the substrate using the mixed polishing liquid when the titanium nitride layer has been polished to.

[0015] In an embodiment, the chemically mechanically polishing the substrate placed on the polishing plate using the second polishing liquid to remove part of the dielectric layer comprises:

[0016] chemically mechanically polishing the substrate using the second polishing liquid to remove the dielectric layer with a preset thickness, the preset thickness being in a range of 40 nm to 200 nm.

[0017] In an embodiment, the mass ratio of the first polishing liquid to the second polishing liquid in the mixed polishing liquid is in a range of 1:1 to 1:4.

[0018] In an embodiment, the first polishing liquid comprises a base liquid, a catalyst and a stabilizer, and the second polishing liquid has the same components as the base liquid.

[0019] In an embodiment, the base liquid comprises solid polishing particles, hydrogen peroxide and water.

[0020] wherein,

[0021] the solid polishing particles are sol-type silicon dioxide.

[0022] the mass percentage of the hydrogen peroxide in the base liquid is in a range of 1% to 3%.

[0023] The mass percentage of the water in the base fluid is 50% to 95%;

[0024] The pH value of the base fluid is 1 to 3.

[0025] In a feasible implementation, the catalyst is ferric nitrate, and the mass percentage of the catalyst in the first polishing liquid is 0.1% to 1%.

[0026] In a feasible implementation, the stabilizer is ammonium persulfate, and the mass percentage of the stabilizer in the first polishing liquid is 0.05% to 1%.

[0027] In a feasible implementation, the solid content of the first polishing liquid and the second polishing liquid is the same, and the solid content is 8% to 14%.

[0028] In a feasible implementation, the average particle size of the solid polishing particles in the first polishing liquid and the second polishing liquid is 100 nm to 140 nm.

[0029] In a feasible implementation, the cleaning liquid is deionized water.

[0030] In a second aspect, the embodiments of the present disclosure provide a chemical mechanical polishing device, comprising:

[0031] a polishing disc;

[0032] a polishing head located above the polishing disc, configured to press a substrate to be polished on the polishing disc for chemical mechanical polishing; the substrate comprises a dielectric layer and a conductive layer, the dielectric layer has a groove, the conductive layer covers the upper surface of the dielectric layer and fills in the groove, and the conductive layer comprises a tungsten layer;

[0033] a polishing liquid supply assembly configured to supply a polishing liquid to the surface of the polishing disc;

[0034] a cleaning assembly configured to supply a cleaning liquid to the surface of the polishing disc;

[0035] a control assembly connected with the polishing liquid supply assembly and the cleaning assembly respectively, and configured to:

[0036] control the polishing liquid supply assembly to supply a mixed polishing liquid of a first polishing liquid and a second polishing liquid to the surface of the polishing disc to remove the conductive layer covering the upper surface of the dielectric layer; the polishing rate of the mixed polishing liquid on the conductive layer is greater than the polishing rate on the dielectric layer;

[0037] control the cleaning assembly to supply a cleaning liquid to the surface of the polishing disc to remove the mixed polishing liquid remaining on the substrate;

[0038] controlling the polishing liquid supply assembly to provide the second polishing liquid to the surface of the polishing plate to remove part of the dielectric layer so that the upper surface of the dielectric layer is lower than the upper surface of the conductive layer filled in the groove, the second polishing liquid having a smaller polishing rate on the conductive layer than on the dielectric layer.

[0039] In an embodiment, the conductive layer further comprises a titanium nitride layer between the dielectric layer and the tungsten layer.

[0040] In an embodiment, the number of substrates to be polished on each polishing plate is four.

[0041] The CMP process and device provided in the embodiments of the present disclosure use a new first polishing liquid and a second polishing liquid. For a substrate with a dielectric layer and a conductive layer, a mixed polishing liquid of the first polishing liquid and the second polishing liquid is used to polish the substrate placed on a polishing plate to remove the conductive layer covered by the upper surface of the dielectric layer. Then, a cleaning liquid is used to flush the substrate placed on the polishing plate, and the second polishing liquid is used to polish the substrate placed on the polishing plate to remove part of the dielectric layer so that the upper surface of the dielectric layer is lower than the upper surface of the conductive layer filled in the groove, thereby ensuring that the conductive layer in the groove protrudes from the surface of the dielectric layer, and improving the product yield of the CMP process based on a single polishing plate. BRIEF DESCRIPTION OF DRAWINGS

[0042] Figure 1 A flowchart of a CMP process based on a double polishing plate provided in the embodiments of the present disclosure;

[0043] Figure 2 A flowchart of a CMP process based on a single polishing plate provided in the embodiments of the present disclosure;

[0044] Figure 3 A flowchart of a CMP process provided in the embodiments of the present disclosure;

[0045] Figure 4 A flowchart of a CMP process provided in the embodiments of the present disclosure;

[0046] Figure 5 A flowchart of the influence of the flow rate of the first polishing liquid and the second polishing liquid on the polishing rate of W and oxide provided in the embodiments of the present disclosure;

[0047] Figure 6 A flowchart of the product results of several CMP processes described in the embodiments of the present disclosure;

[0048] Figure 7A structural schematic diagram of a chemical mechanical polishing device provided in an embodiment of the present disclosure.

[0049] Label description:

[0050] 10 substrate

[0051] 20 dielectric layer

[0052] 30 conductive layer

[0053] 31 tungsten (W) layer

[0054] 32 titanium nitride (TiN) layer

[0055] 311 tungsten plug

[0056] 312 W protruding structure

[0057] 313 recess

[0058] 40 metal structure

[0059] 61 polishing disc

[0060] 62 polishing pad

[0061] 63 polishing head

[0062] 64 polishing liquid supply assembly

[0063] 6411 first polishing liquid supply source

[0064] 6412 second polishing liquid supply source

[0065] 6421 first liquid delivery tube

[0066] 6422 second liquid delivery tube

[0067] 6431 first spray head

[0068] 6432 second spray head

[0069] 65 control assembly

[0070] 66 cleaning assembly DETAILED DESCRIPTION

[0071] In order to make the objects, technical solutions and advantages of the embodiments of the present disclosure clearer, the following will be combined with the drawings in the embodiments of the present disclosure to make a clear and complete description of the technical solutions in the embodiments of the present disclosure. Obviously, the described embodiments are only a part of the embodiments of the present disclosure, rather than all the embodiments. Based on the embodiments in the present disclosure, all other embodiments obtained by those of ordinary skill in the art without creative work belong to the scope of protection of the present disclosure. In addition, although the disclosure is introduced according to one or more exemplary examples, it should be understood that each aspect of the disclosure can also constitute a complete embodiment independently.

[0072] It should be noted that the brief description of the terms in the present disclosure is only for the convenience of understanding the subsequently described embodiments, and is not intended to limit the embodiments of the present disclosure. Unless otherwise specified, these terms should be understood according to their ordinary and general meanings.

[0073] The terms "first", "second", and the like in the specification and claims of the present disclosure and the above-described drawings are used to distinguish similar or similar objects or entities, and do not necessarily mean to limit the specific order or sequence, unless otherwise specified. It should be understood that the terms used in this way can be interchanged under appropriate circumstances, for example, those other than the order given in the embodiment illustration or description of the present disclosure can be implemented.

[0074] In addition, the terms "include" and "have" and any variations thereof are intended to cover but not exclusive inclusion, for example, a product or device including a series of components does not have to be limited to the clearly listed components, but can include other components not clearly listed or inherent to these products or devices.

[0075] The term "module" used in the embodiments of the present disclosure refers to any known or later developed hardware, software, firmware, artificial intelligence, fuzzy logic or a combination of hardware or / and software code capable of performing functions related to the element.

[0076] Optionally, the embodiments of the present disclosure relate to a dynamic random access memory (DRAM) process, which can be applied to the tungsten (W) CMP process in DRAM production.

[0077] In the preparation process of tungsten connection filling holes, a deep well type groove is generally formed in the oxide layer, and then metal tungsten is filled in the groove. In the filling process, the surface of the oxide layer will also be deposited with metal tungsten. At this time, it is necessary to remove the metal tungsten on the surface of the oxide layer by the CMP process, and only the metal tungsten in the groove is retained as the metal connection.

[0078] A conventional CMP process generally uses two polishing pads, as shown in FIG. 1. Figure 1 , Figure 1 FIG. 1 is a flow diagram of a conventional CMP process using two polishing pads.

[0079] As shown in FIG. 2, the CMP process using two polishing pads includes: Figure 1

[0080] Step 1, providing a substrate 10 having a dielectric layer 20 and a conductive layer 30, wherein the dielectric layer 20 has a recess, and the conductive layer 30 covers the upper surface of the dielectric layer 20 and fills the recess.

[0081] The conductive layer 30 includes a tungsten (W) layer 31 and a titanium nitride (TiN) layer 32, and the titanium nitride layer 32 is between the dielectric layer 20 and the tungsten layer 31.

[0082] In some embodiments, the dielectric layer 20 is an oxide.

[0083] Step 2, removing part of the W by using a polishing pad 1 with an A polishing liquid (the polishing rate of W > the polishing rate of oxide).

[0084] Step 3, removing part of the titanium nitride and part of the oxide by using a polishing pad 2 with a B polishing liquid (the polishing rate of oxide > the polishing rate of W), so as to achieve a W protruding structure 312 on the top of the tungsten plug 311, and ensure better contact and connection between the W and the metal layer.

[0085] Since the A polishing liquid and the B polishing liquid contain different raw materials, and the A polishing liquid and the B polishing liquid will react during mixing, it is difficult to remove the by-products formed, so the A polishing liquid can only act on the polishing pad 1 alone, and the B polishing liquid can only act on the polishing pad 2 alone. The W protruding structure can be well formed by the polishing process of the two polishing pads, but in the production line of batch production, more consumables and machines are needed for production, and the utilization rate of the machines is low.

[0086] Therefore, although the CMP process using two polishing pads can achieve the W protruding structure, the utilization rate of the CMP machine is not high.

[0087] In order to improve the utilization rate of the CMP machine, some solutions propose a CMP process based on a single polishing pad. However, the existing CMP process based on a single polishing pad uses a traditional single polishing liquid, which cannot achieve the polishing rate of oxide > the polishing rate of W, so the W is recessed in the process result, and the W protruding structure cannot be formed.

[0088] In order to better understand the embodiments of the present disclosure, refer to Figure 2 , Figure 2 ​A schematic diagram of a CMP process based on a single polishing plate provided in embodiments of the present disclosure.

[0089] As shown in Figure 2 The CMP process based on a single polishing plate includes the following steps:

[0090] Step 1: providing a substrate 10 formed with a dielectric layer 20 and a conductive layer 30, wherein the dielectric layer 20 has a groove, and the conductive layer 30 covers the upper surface of the dielectric layer 20 and fills in the groove.

[0091] The conductive layer 30 includes a tungsten (W) layer 31 and a titanium nitride (TiN) layer 32, and the titanium nitride layer 32 is located between the dielectric layer 20 and the tungsten layer 31.

[0092] In some embodiments, the dielectric layer 20 is an oxide.

[0093] Step 2: removing part of the W and the titanium nitride from the substrate by the polishing plate using a polishing liquid (the polishing rate of W > the polishing rate of oxide).

[0094] Since the polishing rate of the polishing liquid on W is greater than the polishing rate of oxide, a recess 313 will appear on the top of the tungsten plug 311 in the process result, and a W protruding structure cannot be formed. Such a process result increases the processing difficulty of subsequent processes, which may cause the W and the metal layer to be unable to be effectively connected, and seriously affects the yield of the product.

[0095] In addition, if the CMP process based on a single polishing plate uses the A polishing liquid and the B polishing liquid to polish twice in sequence, the surface of the substrate 10 is difficult to be completely washed after the first polishing even after washing, and since the A polishing liquid and the B polishing liquid are greatly different, the A polishing liquid and the B polishing liquid that are not completely washed will react when the second polishing is performed, and the by-products formed are difficult to remove, which will seriously affect the yield of the product.

[0096] To solve the above technical problems, embodiments of the present disclosure provide a chemical mechanical polishing process, which uses a new type of first polishing liquid and second polishing liquid. For a substrate formed with a dielectric layer and a conductive layer, a mixed polishing liquid of the first polishing liquid and the second polishing liquid is used to perform chemical mechanical polishing on the substrate placed on a polishing plate to remove the conductive layer covering the upper surface of the dielectric layer. Then, a cleaning liquid is used to wash the substrate placed on the polishing plate, and then the second polishing liquid is used to perform chemical mechanical polishing on the substrate placed on the polishing plate to remove part of the dielectric layer, so that the upper surface of the dielectric layer is lower than the upper surface of the conductive layer filled in the groove, thereby ensuring that the conductive layer in the groove can protrude from the surface of the dielectric layer, and improving the yield of the product based on the CMP process of a single polishing plate.

[0097] Reference will be made toFigure 3 , Figure 3 FIG. 1 is a flowchart of a chemical mechanical polishing process according to an embodiment of the present disclosure. In some embodiments of the present disclosure, the chemical mechanical polishing process comprises:

[0098] S301, providing a substrate formed with a dielectric layer and a conductive layer, wherein the dielectric layer has a recess, and the conductive layer covers an upper surface of the dielectric layer and fills in the recess.

[0099] In some embodiments, the conductive layer comprises a tungsten layer.

[0100] S302, performing chemical mechanical polishing on the substrate placed on a polishing plate using a mixed slurry of a first slurry and a second slurry, so as to remove the conductive layer covering the upper surface of the dielectric layer.

[0101] In some embodiments, the mixed slurry has a polishing rate on the conductive layer greater than that on the dielectric layer.

[0102] S303, rinsing the substrate placed on the polishing plate using a cleaning liquid, so as to remove the mixed slurry remaining on the substrate.

[0103] S304, performing chemical mechanical polishing on the substrate placed on the polishing plate using the second slurry, so as to remove part of the dielectric layer, and make the upper surface of the dielectric layer lower than the upper surface of the conductive layer filling in the recess.

[0104] In some embodiments, the second slurry has a polishing rate on the conductive layer less than that on the dielectric layer.

[0105] For better understanding of the embodiments of the present disclosure, reference is made to the following detailed description of the embodiments of the present disclosure. Figure 4 , Figure 4 FIG. 2 is a flowchart of a CMP process according to an embodiment of the present disclosure. The CMP process is based on a single polishing plate.

[0106] In some embodiments of the present disclosure, the CMP process comprises:

[0107] Step one, providing a substrate 10 formed with a dielectric layer 20 and a conductive layer 30, wherein the dielectric layer 20 has a recess, and the conductive layer 30 covers an upper surface of the dielectric layer 20 and fills in the recess.

[0108] Optionally, the substrate 10 can be any substrate, such as a silicon substrate, a sapphire substrate, a gallium nitride substrate, etc.

[0109] In some embodiments, the substrate 10 is formed with functional devices requiring electrical leads, such as MOS devices, etc.

[0110] In some embodiments, the dielectric layer 20 is an oxide, such as silicon oxide (SiOx), etc. Alternatively, the dielectric layer 20 can also be silicon nitride (SiN), etc.

[0111] In some embodiments, the dielectric layer 20 can be formed on the front surface of the substrate 10 by a physical vapor deposition process or a chemical vapor deposition process.

[0112] In some embodiments, the above-mentioned recesses can be formed in the dielectric layer 20 by a photolithography and etching process. The number of the recesses formed in the dielectric layer 20 can be set according to actual needs. For example, the number of the recesses formed in the dielectric layer 20 can be multiple.

[0113] In some embodiments, the conductive layer 30 includes a tungsten (W) layer 31 and a titanium nitride (TiN) layer 32, and the titanium nitride layer 32 is located between the dielectric layer 20 and the tungsten layer 31. Alternatively, the titanium nitride layer 32 is located on the sidewalls and the bottom of the above-mentioned recesses, and extends from the above-mentioned recesses to the surface of the dielectric layer 20, and covers the upper surface of the dielectric layer 20; the tungsten layer 31 is located on the upper surface of the titanium nitride layer 32, and the tungsten layer 31 fills the above-mentioned recesses and covers the surface of the titanium nitride layer 32.

[0114] Alternatively, the tungsten layer 31 can be formed by a physical vapor deposition process or a chemical vapor deposition process, etc.

[0115] In other embodiments, the conductive layer 30 can also include other metal layers that can form a conductive metal plug, such as at least one of a copper layer, a tin layer, a titanium layer, a nickel layer, a silver layer, or a gold layer.

[0116] Step two, using a mixed abrasive liquid of the first abrasive liquid and the second abrasive liquid to chemically mechanically polish the substrate 10 placed on the polishing plate, so as to remove part of the conductive layer 30 covering the surface of the dielectric layer 20.

[0117] In the above-mentioned mixed abrasive liquid, the polishing rate of the tungsten in the conductive layer 30 is greater than the polishing rate of the oxide in the dielectric layer 20.

[0118] In the above-mentioned mixed abrasive liquid, the basic components and concentrations of the first abrasive liquid and the second abrasive liquid are similar, so that the mixed abrasive liquid of the first abrasive liquid and the second abrasive liquid can be mixed and polished on the same polishing plate.

[0119] It should be noted that in the chemical mechanical polishing process, the device to be polished is fixed on a polishing head, the polishing head presses the device to be polished on the polishing plate located on the upper surface of the polishing platform, the polishing liquid supply system sprays the polishing liquid on the above-mentioned polishing plate while the above-mentioned polishing platform drives the above-mentioned polishing plate to rotate, and the above-mentioned polishing head drives the above-mentioned device to be polished to rotate in the opposite direction of the above-mentioned polishing plate, so as to polish the above-mentioned device to be polished.

[0120] In some embodiments, during the chemical mechanical polishing of the substrate 10 using the mixed slurry described above, a preset chemical mechanical polishing endpoint detection program is used to detect whether the titanium nitride layer 32 has been polished; when it is detected that the titanium nitride layer 32 has been polished, the chemical mechanical polishing of the substrate using the mixed slurry is stopped.

[0121] In some embodiments, the chemical mechanical polishing endpoint detection program described above can be a friction-based endpoint detection program.

[0122] The friction-based endpoint detection program is to judge the polishing interface by the different friction coefficients of the materials relative to the polishing pad. The specific implementation methods include indirect measurement method and direct measurement method. The direct measurement method is to directly measure the polishing friction to achieve endpoint detection. For example, the friction between the material being polished and the polishing pad will generate resistance to the swing of the polishing head, and a force pressure piezoelectric sensor is used to monitor the lateral force received by the polishing head. When the material of the polishing interface changes, the lateral friction will change, and the endpoint detection can be achieved by directly measuring the change of the friction. The indirect method is an endpoint detection method by detecting the change of the polishing motor current caused by the change of the polishing friction. In order to maintain the stability of the swing and rotation of the polishing head, the current intensity of the polishing head driving motor will change with the change of the rotation resistance of the polishing head and the rotation torque of the polishing disc. Therefore, by measuring the driving current of the motor, the motor resistance of the polishing head and other parameters in real time, the endpoint of the polishing can be judged.

[0123] In some other embodiments, the chemical mechanical polishing endpoint detection program described above can also be an optical-based endpoint detection program, an electromagnetic coupling endpoint detection program, an electrochemical endpoint detection program, a thermal imaging endpoint detection program, etc., which are not limited in the embodiments of the present disclosure.

[0124] Step three, using a cleaning liquid to rinse the substrate 10 placed on the polishing disc to remove the mixed slurry remaining on the substrate 10.

[0125] In some embodiments, deionized water (DIW) can be used to rinse the substrate 10 placed on the polishing disc to remove the mixed slurry remaining on the substrate 10, so as to avoid excessive polishing of the W in the groove.

[0126] Step four, using a second slurry to chemically mechanically polish the substrate 10 placed on the polishing disc to remove part of the dielectric layer 20, so that the upper surface of the dielectric layer 20 is lower than the upper surface of the conductive layer 30 filled in the groove, and a W protruding structure 312 is formed on the top of the tungsten plug 311.

[0127] The second slurry described above has a polishing rate on the oxide in the dielectric layer 20 that is greater than the polishing rate on the W in the conductive layer 30.

[0128] It can be understood that, since the polishing rate of the second polishing liquid to the oxide is greater than the polishing rate to W, after the substrate 10 placed on the polishing plate is polished by the second polishing liquid for a period of time, the upper surface of the dielectric layer 20 is lower than the top surface of the tungsten plug 311 filled in the groove.

[0129] In some embodiments, the polishing thickness can be set, and then the oxide of the thickness can be polished away using the second polishing liquid, and then the polishing can be stopped.

[0130] Optionally, the polishing thickness can be in the range of 40 nm to 200 nm.

[0131] The CMP process provided in the embodiments of the present disclosure includes the following steps: after a substrate with a dielectric layer and a conductive layer is provided, the substrate placed on a polishing plate is polished by a mixed polishing liquid of a first polishing liquid and a second polishing liquid to remove the conductive layer covered by the upper surface of the dielectric layer; then the substrate placed on the polishing plate is rinsed by a cleaning liquid, and then the substrate placed on the polishing plate is polished by the second polishing liquid to remove part of the dielectric layer, so that the upper surface of the dielectric layer is lower than the upper surface of the conductive layer filled in the groove, thereby ensuring that the conductive layer in the groove can protrude from the surface of the dielectric layer, and the product yield of the CMP process based on a single polishing plate is improved.

[0132] In the embodiments of the present disclosure, a new type of first polishing liquid and second polishing liquid are provided. The basic components and concentrations of the first polishing liquid and the second polishing liquid are similar, thereby helping to realize the mixed polishing of the two polishing liquids on the same polishing plate without chemical reaction to generate insoluble substances.

[0133] In some embodiments, the first polishing liquid can be obtained by adding an appropriate amount of catalyst (Catalyst) and stabilizer (Stabilizer) to the second polishing liquid, to increase the polishing rate of W, but the polishing rate to the oxide is basically constant.

[0134] In some embodiments of the present disclosure, if the second polishing liquid is used as the base liquid, the first polishing liquid includes the base liquid and the above-mentioned catalyst and stabilizer.

[0135] Optionally, the base liquid includes solid polishing particles, hydrogen peroxide and water.

[0136] The solid polishing particles are sol-type silicon dioxide or cerium dioxide; the mass percentage of the hydrogen peroxide in the base liquid is 1% to 3%; the mass percentage of the water in the base liquid is 50% to 95%; and the pH value of the base liquid is 1 to 3.

[0137] Optionally, the first polishing liquid and the second polishing liquid have the same solid content, and the solid content is 8% to 14%.

[0138] Optionally, the average particle size of the solid polishing particles in the first polishing liquid and the second polishing liquid is 100 nm to 140 nm.

[0139] For better understanding of the embodiments of the present disclosure, refer to Table 1, which is a component comparison table of the first polishing liquid and the second polishing liquid.

[0140] Table 1: Component comparison table of the first polishing liquid and the second polishing liquid

[0141] Ingredients First polishing liquid Second polishing liquid Solid polishing particles Sol-gel Sol-gel Average particle size 100 nm to 140 nm 100 nm to 140 nm Hydrogen peroxide 1％～3％ 1％～3％ Water 50％～95％ 50％～95％ Solid content 8％～14％ 8％～14％ pH 1～3 1～3 Other Catalyst + stabilizer None

[0142] Optionally, the catalyst is soluble iron, such as ferric nitrate, etc. In the presence of hydrogen peroxide (H2O2), the surface of W is easily oxidized, making the surface of W soft and easier to remove.

[0143] Optionally, the mass percentage of the catalyst in the first polishing liquid is 0.1% to 1%.

[0144] Optionally, the stabilizer is an organic acid and its salt, such as ammonium persulfate, etc.

[0145] Optionally, the mass percentage of the stabilizer in the first polishing liquid is 0.05% to 1%.

[0146] For better understanding of the embodiments of the present disclosure, refer to Figure 5 , Figure 5 is a schematic diagram of the influence of the flow rate of the first polishing liquid and the second polishing liquid on the polishing rate of W and oxide in the embodiments of the present disclosure.

[0147] In Figure 5 , a represents the maximum flow rate of the first polishing liquid, and b represents the maximum flow rate of the second polishing liquid.

[0148] From Figure 5As can be seen, when the maximum flow rate of the first grinding fluid is 0 cc and the maximum flow rate of the second grinding fluid is 200 cc (equivalent to providing only the second grinding fluid to the grinding disc), the grinding rate of the oxide is greater than that of W. When the maximum flow rate of the first grinding fluid increases (e.g., the maximum flow rate of the first grinding fluid exceeds 50 cc), the grinding rate of W becomes greater than that of the oxide. With the increase of the maximum flow rate of the first grinding fluid, i.e., the increase of the amount of catalyst and stabilizer in the grinding fluid, the grinding rate of W is expected to increase accordingly. However, unexpectedly, the actual grinding rate of W remains essentially unchanged. One explanation is that although catalyst and stabilizer are added to the first grinding fluid, and their amounts are continuously increasing, the amount that can come into contact with W is limited. When the first grinding fluid is added to the second grinding fluid to a certain extent, saturation is reached, and the grinding rate of W does not change significantly. Furthermore, considering that the polishing slurries used in the first polishing (polishing the conductive layer) and the second polishing (polishing the dielectric layer) during the single-disc polishing process should be as similar as possible, otherwise, if the polishing slurries used are significantly different, on the one hand, the two polishing slurries may react; on the other hand, during the polishing transition period, the first polishing (polishing the conductive layer) cannot be quickly switched to the second polishing (polishing the dielectric layer), resulting in over-polishing of the conductive layer. Moreover, from the perspective of cost optimization, in some embodiments of this disclosure, when polishing the conductive layer covering the upper surface of the dielectric layer, a mixture of the first and second polishing slurries is used; when polishing the dielectric layer, the second polishing slurry is used. Furthermore, when the first and second polishing slurries are used in combination, the mass ratio of the first and second polishing slurries can be 1:1 to 1:4. Additionally, when polishing the conductive layer covering the upper surface of the dielectric layer, considering that a higher selectivity ratio of polishing slurry for the conductive layer and the dielectric layer is better, the mass ratio of the first and second polishing slurries is preferably 1:1.

[0149] To better understand the embodiments of this disclosure, please refer to... Figure 6 , Figure 6 This is a schematic diagram comparing the product results of several CMP processes described in the embodiments of this disclosure.

[0150] from Figure 6 As can be seen, in traditional CMP processes based on a single grinding disc, the tungsten plug 311 cannot form a W-shaped protrusion structure on its top, resulting in an ineffective connection between the tungsten plug 311 and the metal structure 40, posing a risk of open circuit. However, the novel CMP process based on a single grinding disc provided in this embodiment allows for an effective connection between the tungsten plug 311 and the metal structure 40 because the top of the tungsten plug 311 can form a W-shaped protrusion structure. The resulting product achieves the same level of performance as traditional CMP processes based on dual grinding discs.

[0151] The chemical mechanical polishing process method provided in the embodiments of the present disclosure can realize W protruding structures on a single polishing disc by preparing two new types of polishing liquids, thereby improving the utilization rate of the polishing machine and ensuring the yield of products.

[0152] Based on the above-described content in the embodiments, the present disclosure further provides a chemical mechanical polishing device. Referring to Figure 7 , Figure 7 FIG. 1 is a structural schematic diagram of a chemical mechanical polishing device provided in the embodiments of the present disclosure. The chemical mechanical polishing device comprises:

[0153] a polishing disc 61.

[0154] a polishing pad 62 located on the upper surface of the polishing disc 61.

[0155] a polishing head 63 located above the polishing pad 62 and used for pressing a substrate to be polished on the polishing pad 62 for chemical mechanical polishing.

[0156] a polishing liquid supply assembly 64 used for supplying a first polishing liquid and a second polishing liquid to the surface of the polishing pad 62.

[0157] Optionally, the polishing liquid supply assembly 64 comprises a first polishing liquid supply source 6411, a second polishing liquid supply source 6412, a first liquid delivery pipe 6421, a second liquid delivery pipe 6422, a first spray head 6431 and a second spray head 6432; one end of the first liquid delivery pipe 6421 is connected with the first polishing liquid supply source 6411, the other end is connected with the first spray head 6431, and the first spray head 6431 is located above the polishing pad 62; one end of the second liquid delivery pipe 6422 is connected with the second polishing liquid supply source 6412, the other end is connected with the second spray head 6432, and the second spray head 6432 is located above the polishing pad 62.

[0158] In a possible implementation, the first polishing liquid supply source 6411 is used for supplying the first polishing liquid, and the second polishing liquid supply source 6412 is used for supplying the second polishing liquid.

[0159] Alternatively, the first polishing liquid supply source 6411 is used for supplying a mixed polishing liquid of the first polishing liquid and the second polishing liquid, and the second polishing liquid supply source 6412 is used for supplying the second polishing liquid.

[0160] a control assembly 65 connected with the polishing liquid supply assembly 64 and used for adjusting the type and flow rate of the polishing liquid supplied by the polishing liquid supply assembly 64 to the polishing pad 62.

[0161] a cleaning assembly 66 used for supplying a cleaning liquid to the surface of the polishing disc.

[0162] In one embodiment, the control component 65 is connected to the first slurry supply source 6411 and the second slurry supply source 6412.

[0163] The control component 65 is connected to the cleaning component 66, and is configured to provide a cleaning liquid to the surface of the polishing pad 62 after the first polishing process to remove the mixed slurry from the polishing pad 62.

[0164] The control component 65 is further configured to control the second slurry supply source 6412 to provide the second slurry to the surface of the polishing pad 62 during the second polishing process.

[0165] In some embodiments of the present disclosure, the substrate to be polished has a dielectric layer and a conductive layer formed thereon. The dielectric layer has a recess, and the conductive layer covers the top surface of the dielectric layer and fills the recess. The conductive layer includes a tungsten (W) layer and a titanium nitride layer, and the titanium nitride layer is between the dielectric layer and the tungsten layer. Optionally, the titanium nitride layer is on the sidewall and bottom of the recess, extends from the recess to the surface of the dielectric layer, and covers the top surface of the dielectric layer; the tungsten layer is on the top surface of the titanium nitride layer, fills the recess, and covers the surface of the titanium nitride layer.

[0166] In some embodiments, the dielectric layer is an oxide, such as silicon oxide (SiOx).

[0167] In some embodiments, during the first polishing process, the control component 65 can control the first slurry supply source 6411 to provide the mixed slurry of the first slurry and the second slurry to the surface of the polishing pad 62; or the control component 65 can control the first slurry supply source 6411 to provide the first slurry to the surface of the polishing pad 62 at a first flow rate, and control the second slurry supply source 6412 to provide the second slurry to the surface of the polishing pad 62 at a second flow rate.

[0168] Since the mixed slurry of the first slurry and the second slurry has a higher polishing rate on the tungsten in the conductive layer than on the oxide in the dielectric layer, during the first polishing process, part of the conductive layer covering the surface of the dielectric layer can be removed.

[0169] In some embodiments, the CMP device further includes a detection device configured to detect whether the titanium nitride layer has been polished to during the first polishing process using a preset CMP endpoint detection program; and stop the first polishing process when it is detected that the titanium nitride layer has been polished to.

[0170] In some embodiments, the CMP endpoint detection program can be a friction-based endpoint detection program.

[0171] In some embodiments, the CMP endpoint detection procedure described above can also be an optical-based endpoint detection procedure, an electromagnetic coupling endpoint detection procedure, an electrochemical endpoint detection procedure, a thermal imaging endpoint detection procedure, etc., and the present disclosure is not limited thereto.

[0172] In some embodiments, after the first polishing is stopped, the control component 65 can control the cleaning component 66 to provide a cleaning liquid to the surface of the polishing plate to remove the mixed polishing liquid remaining on the substrate.

[0173] In some embodiments, deionized water (DIW) can be used to rinse the substrate placed on the polishing plate to avoid over-polishing the W in the recess.

[0174] In some embodiments, after the substrate is rinsed, the second polishing can be started, and during the second polishing, the control component 65 can control the second polishing supply source 6412 to provide the second polishing liquid to the surface of the polishing pad 62.

[0175] It can be understood that, since the polishing rate of the second polishing liquid on the oxide is greater than that on the W, after the substrate placed on the polishing plate is polished by the second polishing liquid for a period of time, the upper surface of the dielectric layer will be lower than the top surface of the tungsten plug filled in the recess.

[0176] In some embodiments, a polishing thickness can be set, and then the second polishing liquid can be used to polish away the thickness of the oxide, and then the polishing can be stopped.

[0177] Optionally, the polishing thickness can be in the range of 40 nm to 200 nm.

[0178] In some embodiments, the first polishing liquid can be obtained by adding an appropriate amount of catalyst (Catalyst) and stabilizer (Stabilizer) to the second polishing liquid to increase the polishing rate of W, but the polishing rate on the oxide is basically constant.

[0179] In some embodiments of the present disclosure, if the second polishing liquid is used as the base liquid, the first polishing liquid includes the base liquid and the catalyst and the stabilizer described above.

[0180] Optionally, the base liquid includes solid polishing particles, hydrogen peroxide, and water.

[0181] In the above, the solid polishing particles are sol-gel silica or ceria; the mass percentage of the hydrogen peroxide in the base liquid is 1% to 3%; the mass percentage of the water in the base liquid is 50% to 95%; and the pH value of the base liquid is 1 to 3.

[0182] Optionally, the first polishing liquid and the second polishing liquid have the same solid content, and the solid content is 8% to 14%.

[0183] Optionally, the solid polishing particles in the first polishing liquid and the second polishing liquid have an average particle size of 100 nm to 140 nm.

[0184] Optionally, the catalyst is soluble iron, such as ferric nitrate and the like. In the presence of hydrogen peroxide (H2O2), the W surface is easily oxidized, making the W surface soft and easier to remove.

[0185] Optionally, the mass percentage of the catalyst in the first polishing liquid is 0.1% to 1%.

[0186] Optionally, the stabilizer is an organic acid and a salt thereof, such as ammonium persulfate and the like.

[0187] Optionally, the mass percentage of the stabilizer in the first polishing liquid is 0.05% to 1%.

[0188] In addition, in order to make the polishing liquid used in the first polishing (polishing of the conductive layer) and the second polishing (polishing of the dielectric layer) as similar as possible, otherwise, the difference between the two polishing liquids is too large, on the one hand, the two polishing liquids can react with each other, on the other hand, during the polishing transition, the first polishing (polishing of the conductive layer) cannot be quickly switched to the second polishing (polishing of the dielectric layer), thereby causing over-polishing of the conductive layer, and from the perspective of optimizing the cost, in some embodiments of the present disclosure, when the conductive layer covering the upper surface of the dielectric layer is polished, a mixed polishing liquid of the first polishing liquid and the second polishing liquid is used; when the dielectric layer is polished, the second polishing liquid is used. In some embodiments of the present disclosure, when the first polishing liquid and the second polishing liquid are used in the mixed polishing liquid, the mass ratio of the first polishing liquid to the second polishing liquid can be 1:1 to 1:4, in addition, when the conductive layer covering the upper surface of the dielectric layer is polished, it is considered that the larger the polishing liquid selection ratio of the conductive layer to the dielectric layer is, the better, therefore, the mass ratio of the first polishing liquid to the second polishing liquid is preferably 1:1.

[0189] It can be understood that, by using the single polishing disc process, the chemical mechanical polishing device provided in the embodiments of the present disclosure can switch the traditional 2x2 production mode of the machine to a 4x1 mode, thereby greatly improving the utilization rate of the machine and saving production costs. The 2x2 production mode refers to that the machine uses two polishing discs, each polishing disc uses a different polishing process, and two wafers can be polished at the same time. The 4x1 mode refers to that the machine uses one polishing disc, and the polishing disc can polish four wafers at the same time.

[0190] The chemical mechanical polishing device provided in the embodiments of the present disclosure can realize W protruding structures on a single polishing disc by using two new types of polishing liquid, thereby improving the utilization rate of the polishing machine and ensuring the yield of products.

[0191] In several embodiments provided in the present disclosure, it should be understood that the disclosed devices and methods can be implemented in other manners. For example, the embodiments of the device described above are merely schematic, and the division of the modules is merely a logical function division, and there can be another division manner in actual implementation. For example, a plurality of modules or features can be combined or integrated into another system, or some features can be ignored or not executed. In addition, the displayed or discussed mutual couplings or direct couplings or communication connections between different modules can be indirect couplings or communication connections through some interfaces, devices or modules, and can be electrical, mechanical or in other forms.

[0192] The modules described as separated components can or can not be physically separated, and the components displayed as modules can or can not be physical units, i.e., can be located in one place, or can be distributed on a plurality of network units. Part or all of the modules can be selected according to actual needs to achieve the purpose of the embodiments.

[0193] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present disclosure, but not to limit them; although the present disclosure has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that: it can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacement to part or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present disclosure.

Claims

1. A chemical mechanical grinding process, characterized in that, include: A substrate having a dielectric layer and a conductive layer formed thereon is provided, wherein the dielectric layer has a groove, the conductive layer covers the upper surface of the dielectric layer and fills the groove, and the conductive layer includes a tungsten layer. The substrate placed on the grinding disc is subjected to chemical mechanical polishing using a mixture of a first polishing slurry and a second polishing slurry to remove the conductive layer covering the upper surface of the dielectric layer; The grinding rate of the mixed grinding fluid on the conductive layer is greater than that on the dielectric layer; The substrate placed on the grinding disc is rinsed with a cleaning solution to remove any residual mixed grinding solution from the substrate; The substrate placed on the grinding disc is chemically and mechanically ground using the second polishing slurry to remove part of the dielectric layer, so that the upper surface of the dielectric layer is lower than the upper surface of the conductive layer filling the groove. The polishing rate of the second polishing slurry on the conductive layer is less than the polishing rate on the dielectric layer. In the mixed grinding fluid, the mass ratio of the first grinding fluid to the second grinding fluid is 1:1 to 1:4; The first polishing slurry includes a base liquid, a catalyst, and a stabilizer, and the composition of the second polishing slurry is the same as that of the base liquid.

2. The method according to claim 1, characterized in that, The conductive layer further includes a titanium nitride layer, which is located between the dielectric layer and the tungsten layer.

3. The method according to claim 2, characterized in that, The step of performing chemical mechanical polishing on the substrate placed on a polishing pad using a mixture of a first polishing slurry and a second polishing slurry to remove the conductive layer covering the upper surface of the dielectric layer includes: During the chemical mechanical polishing of the substrate using the mixed polishing slurry, a preset chemical mechanical polishing endpoint detection program is used to detect whether the titanium nitride layer has been polished to the end. When it is detected that the titanium nitride layer has been ground down, the chemical mechanical polishing of the substrate using the mixed polishing slurry is stopped.

4. The method according to claim 1, characterized in that, The step of using the second polishing slurry to perform chemical mechanical polishing on the substrate placed on the polishing disc to remove part of the dielectric layer includes: The substrate is chemically and mechanically polished using the second polishing slurry to remove the dielectric layer of a predetermined thickness; the predetermined thickness is in the range of 40 nm to 200 nm.

5. The method according to claim 1, characterized in that, The base liquid comprises solid abrasive particles, hydrogen peroxide, and water; wherein... The solid abrasive particles are sol-gel silica; The hydrogen peroxide in the base solution has a mass percentage of 1% to 3%; The water in the base liquid is 50% to 95% by mass; The pH value of the base solution is 1 to 3.

6. The method according to claim 1, characterized in that, The catalyst is ferric nitrate, and the mass percentage of the catalyst in the first grinding slurry is 0.1% to 1%.

7. The method according to claim 1, characterized in that, The stabilizer is ammonium persulfate, and the mass percentage of the stabilizer in the first grinding slurry is 0.05% to 1%.

8. The method according to claim 5, characterized in that, The first polishing slurry and the second polishing slurry have the same solid content, which is 8% to 14%.

9. The method according to claim 8, characterized in that, The average particle size of the solid grinding particles in the first grinding slurry and the second grinding slurry is 100nm to 140nm.

10. The method according to claim 1, characterized in that, The cleaning solution is deionized water.

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