Preparation method of conductive plug, preparation method of semiconductor device and semiconductor device

Abstract

The invention provides a preparation method of a conductive plug, a preparation method of a semiconductor device and the semiconductor device. The preparation method comprises the following steps that a to-be-ground substrate is provided, the to-be-ground substrate comprises an insulating layer, a barrier layer and a conductive layer, a plug hole is formed in the insulating layer, the barrier layer is arranged on the top face of the insulating layer and extends to cover the hole wall of the plug hole, and the conductive layer is arranged on the barrier layer; performing first grinding treatment on the conductive layer, wherein the first grinding treatment is stopped on the surface of the barrier layer; performing second grinding treatment on the conductive layer after the first grinding treatment; performing third grinding treatment on the barrier layer and the conductive layer, wherein the third grinding treatment is stopped on the surface of the insulating layer; and performing fourth grinding treatment on the insulating layer and the conductive layer. According to the preparation method, the thinning amount of the conductive layer can be more controllable, the quality of the prepared conductive plug can be improved, and the device has a higher yield.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor technology, and in particular to a method for preparing a conductive plug, a method for preparing a semiconductor device, and a semiconductor device. Background Art

[0002] Conductive plugs are usually arranged in the insulating layer and used to realize the electrical connection between the upper and lower structures of the insulating layer. They are common structures in semiconductor devices. Conductive plugs are usually prepared by first depositing conductive material in the plug hole and then etching back. As the size of semiconductor devices gradually decreases, the aspect ratio of the plug hole used to prepare the conductive plug will gradually increase. When the conductive material is deposited in a plug hole with a large depth-to-width ratio, the conductive material deposited on the hole wall has the problem of intersection and premature sealing, which eventually leaves a gap inside the conductive plug. When etching back the conductive material, the traditional process of etching back the conductive material has the problem of difficult to control the grinding amount. In the actual etching back process, it is easy to expose the gaps in the conductive material, and thus significantly reduce the quality of the conductive plug and the yield of the device. Summary of the invention

[0003] Based on this, it is necessary to provide a method for preparing a conductive plug to address the problems in the above background technology, so as to improve the controllability of the conductive material during the etching back process, thereby improving the quality of the conductive plug and the yield of the device.

[0004] According to some embodiments of the present disclosure, a method for preparing a conductive plug is provided, which comprises the following steps:

[0005] Providing a substrate to be polished, the substrate to be polished comprising an insulating layer, a barrier layer and a conductive layer, the insulating layer having a plug hole, the barrier layer being arranged on the top surface of the insulating layer and extending to cover the hole wall of the plug hole, and the conductive layer being arranged on the barrier layer;

[0006] Performing a first grinding process on the conductive layer, wherein the first grinding process stops at a surface of the barrier layer;

[0007] performing a second grinding process on the conductive layer after the first grinding process;

[0008] Performing a third grinding process on the barrier layer and the conductive layer, wherein the third grinding process stops at a surface of the insulating layer;

[0009] The insulating layer and the conductive layer are subjected to a fourth grinding process.

[0010] In some embodiments of the present disclosure, after the fourth grinding process, the top of the conductive layer is higher than or equal to the top of the insulating layer.

[0011] In some embodiments of the present disclosure, in the step of performing a fourth grinding process on the insulating layer and the conductive layer, a thinning rate of the conductive layer is controlled to be smaller than a thinning rate of the insulating layer.

[0012] In some embodiments of the present disclosure, after the third grinding process, the height difference between the bottom end of the conductive layer and the top surface of the insulating layer is H. C3 During the fourth grinding process, the conductive layer is reduced by H C4 ; where H C3 With H C4 The sum is less than the thinning amount of the insulating layer during the fourth grinding process.

[0013] In some embodiments of the present disclosure, the time of the second grinding process is controlled accordingly according to the initial thickness of the insulating layer, so that the top of the conductive layer is higher than or equal to the top of the insulating layer.

[0014] Before the first grinding process, the initial thickness of the insulating layer is H 0 The target thickness of the insulating layer retained after the fourth grinding process is preset to be H T After the first grinding process and before the second grinding process, the thickness of the barrier layer is H B The time required for the second grinding process is T 2 , the thinning rate of the conductive layer during the second grinding process is R C1 The thinning rate of the conductive layer during the third grinding process is R C2 The thinning rate of the conductive layer during the fourth grinding process is R C4 The thinning rate of the barrier layer during the third grinding process is R B The thinning rate of the insulating layer during the fourth grinding process is R T , where each parameter satisfies the following relationship: .

[0015] In some embodiments of the present disclosure, after the second grinding process, the height difference between the bottom end of the conductive layer and the top surface of the barrier layer is 0 nm to 50 nm.

[0016] In some embodiments of the present disclosure, the mode used in the step of performing the fourth grinding treatment is process control feedback, and the polishing time is dynamically controlled according to the thickness of the insulating layer before the fourth grinding treatment so that the thinned insulating layer reaches a preset target thickness.

[0017] In some embodiments of the present disclosure, the material of the insulating layer is selected from one or more of silicon nitride, silicon carbide, silicon dioxide, silicon oxynitride and black diamond; and / or,

[0018] The material of the conductive layer is selected from one or more of tungsten, aluminum, copper, gold and silver; and / or,

[0019] The material of the barrier layer is selected from one or more of titanium nitride, tantalum nitride, titanium, tantalum and titanium-tungsten alloy.

[0020] In some embodiments of the present disclosure, the second grinding process is performed immediately after the first grinding process, and the grinding liquid used in the first grinding process is the same as the grinding liquid used in the second grinding process.

[0021] In some embodiments of the present disclosure, the polishing liquid used in the first polishing process includes one or more of amorphous silicon dioxide, hydrogen peroxide, water, a corrosion inhibitor and a barrier layer inhibitor; and / or,

[0022] The polishing liquid used in the second polishing treatment comprises one or more of amorphous silicon dioxide, hydrogen peroxide, water, a corrosion inhibitor and a barrier layer inhibitor; and / or,

[0023] The polishing liquid used in the third polishing process comprises one or more of amorphous silicon dioxide, hydrogen peroxide, water, a corrosion inhibitor and a barrier layer inhibitor; and / or,

[0024] The grinding liquid used in the fourth grinding process includes one or more of amorphous silicon dioxide, hydrogen peroxide, water, citric acid and a chelating agent.

[0025] Furthermore, the present disclosure also provides a method for preparing a semiconductor device, which comprises the following steps:

[0026] An insulating layer, a barrier layer and a conductive layer are sequentially prepared on the functional structure as a substrate to be polished;

[0027] A conductive plug is prepared in the substrate to be ground using the method for preparing a conductive plug as described in any of the above embodiments.

[0028] Furthermore, the present disclosure also provides a semiconductor device, which is prepared by the method for preparing a semiconductor device as described in the above embodiment; or,

[0029] The semiconductor device includes a conductive plug prepared by the conductive plug preparation method described in the above embodiment.

[0030] In the preparation method of the conductive plug disclosed in the present invention, the substrate to be ground is subjected to the first grinding treatment, the second grinding treatment, the third grinding treatment and the fourth grinding treatment in sequence. In the first grinding treatment, the barrier layer is used as the stop layer, the conductive layer is continuously ground as the over-grinding step in the second grinding treatment, and the insulating layer is used as the stop layer in the third grinding treatment. In the preparation method, the over-grinding step, that is, the second grinding treatment step, is arranged before the barrier layer, which can make the thinning amount of the conductive layer more controllable. And in the subsequent third grinding treatment and fourth grinding treatment, there is no need to perform the over-grinding step, so the depression amount of the conductive layer in the plug hole can be reduced, reducing or avoiding the probability of exposing the pores therein. Therefore, the preparation method of the conductive plug can improve the quality of the prepared conductive plug, and thus make the device have a higher yield.

[0031] The above description is only an overview of the technical solution of the present invention. In order to more clearly understand the technical means of the present invention and implement it according to the contents of the specification, the following is a detailed description of the preferred embodiments of the present invention in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] In order to more clearly illustrate the technical solutions of the embodiments of the present disclosure, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present disclosure. For ordinary technicians in this field, drawings of other embodiments can be obtained based on these drawings without creative work.

[0033] Figure 1 A schematic diagram of the steps of a method for preparing a conductive plug;

[0034] Figure 2 is a schematic diagram of the structure of a substrate to be ground;

[0035] Figure 3 For Figure 2 A schematic diagram of the structure after the conductive layer is subjected to a first grinding treatment based on the structure shown;

[0036] Figure 4 For Figure 3 A schematic diagram of a structure after a second grinding process is performed on the structure shown;

[0037] Figure 5 For Figure 4 A schematic diagram of a structure after a third grinding process is performed on the structure shown in FIG.

[0038] Figure 6 For Figure 5 A schematic diagram of a structure after a fourth grinding process is performed on the insulating layer and the conductive layer based on the structure shown;

[0039] Figure 7 A schematic diagram showing the comparison of thickness changes of each layer during step S1 to step S5;

[0040] Figure 8 for Figure 7 Schematic diagram of the enlarged structure of area A in the middle.

[0041] The reference numerals and their meanings are as follows:

[0042] 110, insulating layer; 120, barrier layer; 130, conductive layer; 131, conductive plug. DETAILED DESCRIPTION

[0043] To facilitate understanding of the present invention, a more comprehensive description of the present invention is provided below. The preferred embodiments of the present invention are given herein. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the content of the present invention more thorough and comprehensive.

[0044] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which this document pertains. The terms used herein in the specification of this document are only for describing specific embodiments and are not intended to limit this document.

[0045] It should be understood that when an element or layer is referred to as being "on, "adjacent to, "connected to, or "coupled to" another element or layer, it may be directly on, adjacent to, connected to, or coupled to the other element or layer, or there may be intervening elements or layers. In contrast, when an element is referred to as being "directly on, "directly adjacent to, "directly connected to, or "directly coupled to" another element or layer, there may be no intervening elements or layers. It should be understood that although the terms first, second, third, etc. may be used to describe various elements, components, regions, layers, and / or portions, these elements, components, regions, layers, and / or portions should not be limited by these terms. These terms are merely used to distinguish one element, component, region, layer, or portion from another element, component, region, layer, or portion.

[0046] Spatially relative terms such as "under," "beneath," "below," "under," "above," "above," and the like may be used herein for ease of description to describe the relationship of one element or feature to other elements or features. It should be understood that the spatially relative terms are intended to also include different orientations of the device in use and operation. For example, if the device in the accompanying drawings is flipped, then the elements or features described as "under other elements" or "under" or "under" will be oriented as "over" the other elements or features. Thus, the exemplary terms "under" and "under" may include both upper and lower orientations. The device may be otherwise oriented (e.g., rotated 90 degrees or other orientations) and the spatial descriptors used may be interpreted accordingly.

[0047] The purpose of the terms used herein is only to describe specific embodiments and is not intended to be a limitation of the present disclosure. When used herein, the singular forms "a", "an" and "the" are also intended to include plural forms, unless the context clearly indicates otherwise. It should also be understood that the terms "consisting of" and / or "comprising", when used in this specification, determine the presence of features, integers, steps, operations, elements and / or parts, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, parts and / or groups. When used herein, the term "and / or" includes any and all combinations of the relevant listed items.

[0048] Since the surface of the wafer has certain non-uniformity during the grinding process, it is usually necessary to over-polish the conductive layer during the preparation of the conductive plug. In the related art, the over-polishing step is usually performed after the insulating layer is exposed, and a certain depression is generated on the surface of the conductive layer in the plug hole. At this time, the thinning amount of the conductive layer is difficult to control. If the thinning amount is too large, the depression on the surface of the conductive layer deepens, which can easily lead to the exposure of the gap in the conductive layer during the subsequent grinding process, affecting the quality of the conductive plug and the yield of the device.

[0049] The present disclosure provides a method for preparing a conductive plug, which comprises the following steps:

[0050] A substrate to be ground is provided, which includes an insulating layer, a blocking layer and a conductive layer. The insulating layer has a plug hole, the blocking layer is arranged on the top surface of the insulating layer and extends to cover the hole wall of the plug hole, and the conductive layer is arranged on the blocking layer.

[0051] The conductive layer is subjected to a first grinding process, and the first grinding process stops at a surface of the barrier layer.

[0052] The conductive layer after the first grinding process is subjected to a second grinding process.

[0053] The barrier layer and the conductive layer are subjected to a third grinding process, and the third grinding process stops at a surface of the insulating layer.

[0054] The insulating layer and the conductive layer are subjected to a fourth grinding process.

[0055] In the preparation method of the conductive plug disclosed in the present invention, the substrate to be ground is subjected to the first grinding treatment, the second grinding treatment, the third grinding treatment and the fourth grinding treatment in sequence. In the first grinding treatment, the barrier layer is used as the stop layer, the conductive layer is continuously ground as the over-grinding step in the second grinding treatment, and the insulating layer is used as the stop layer in the third grinding treatment. In the preparation method, the over-grinding step, that is, the second grinding treatment step, is arranged before the barrier layer, which can make the thinning amount of the conductive layer more controllable. And in the subsequent third grinding treatment and fourth grinding treatment, there is no need to perform the over-grinding step, so the depression amount of the conductive layer in the plug hole can be reduced, reducing or avoiding the probability of exposing the pores therein. Therefore, the preparation method of the conductive plug can improve the quality of the prepared conductive plug, and thus make the device have a higher yield.

[0056] In order to facilitate understanding of the specific implementation of the present disclosure, the present disclosure further provides specific steps of a method for preparing a conductive plug. Figure 1 Schematic diagram of the steps of the method for preparing the conductive plug, which includes steps S1 to S5, as follows.

[0057] Step S1, providing a substrate to be ground.

[0058] Figure 2 Schematic diagram of the structure of a substrate to be ground. Figure 2 As shown, the substrate to be polished includes an insulating layer 110, a barrier layer 120 and a conductive layer 130. The insulating layer 110 has a plug hole, the barrier layer 120 is disposed on the top surface of the insulating layer 110 and extends to cover the hole wall of the plug hole, and the conductive layer 130 is disposed on the barrier layer 120.

[0059] The insulating layer 110 is made of insulating materials and is used to insulate and space components above and below it. The barrier layer 120 is used to isolate the conductive layer 130 and the insulating layer 110 and to prevent atoms of the conductive layer 130 from diffusing outward.

[0060] As some examples of this embodiment, a functional structure may be further provided in the substrate to be ground, and the functional structure may be provided below the insulating layer 110 .

[0061] The material of the insulating layer 110 should be an insulating material. As some examples of this embodiment, the material of the insulating layer 110 may be selected from one or more of silicon nitride, silicon carbide, silicon dioxide, silicon oxynitride and black diamond.

[0062] The material of the conductive layer 130 should be a conductive material. As some examples of this embodiment, the material of the conductive layer 130 is selected from one or more of tungsten, aluminum, copper, gold and silver.

[0063] The material of the barrier layer 120 should be selected from materials having strong blocking capability for atoms of the conductive layer 130. As some examples of this embodiment, the material of the barrier layer 120 is selected from one or more of titanium nitride, tantalum nitride, titanium, tantalum and titanium-tungsten alloy.

[0064] As some examples of this embodiment, the step of providing a substrate to be ground may include: sequentially preparing an insulating layer 110 , a barrier layer 120 , and a conductive layer 130 on the functional structure.

[0065] Further, in this example, the step of preparing the insulating layer 110 on the functional structure includes: depositing an insulating material on the functional structure, and etching the insulating material to form a plug hole. The method of depositing the insulating material is chemical vapor deposition or atomic layer deposition, and the method of etching the insulating material is selected from wet etching or dry etching.

[0066] In this example, the barrier layer 120 is prepared on the functional structure by chemical vapor deposition or atomic layer deposition. Figure 2 As shown, the material of the barrier layer 120 can be deposited on the top surface of the insulating layer 110 and the wall of the plug hole at the same time.

[0067] In this example, the conductive layer 130 is prepared on the functional structure by chemical vapor deposition or atomic layer deposition. Figure 2 As shown, the material of the conductive layer 130 is deposited on a side of the barrier layer 120 away from the insulating layer 110 . Specifically, the conductive layer 130 may be located in the plug hole and cover the top surface of the barrier layer 120 .

[0068] In step S2 , the conductive layer 130 is subjected to a first grinding process, and the first grinding process stops at the surface of the barrier layer 120 .

[0069] Figure 3 For Figure 2 A schematic diagram of a structure after the conductive layer 130 is subjected to a first grinding process based on the structure shown in FIG. Figure 3 As shown, after the first grinding process, the conductive layer 130 located above the barrier layer 120 is removed, and the shielded barrier layer 120 is exposed. In this embodiment, the barrier layer 120 serves as a stop layer for the first grinding process, that is, the first grinding process is stopped when the grinding reaches the barrier layer 120. The first grinding process can be performed in an endpoint control mode.

[0070] As some examples of this embodiment, after the first grinding process, the surface of the remaining conductive layer 130 may be flush with the surface of the barrier layer 120 .

[0071] As some examples of this embodiment, the first grinding process is chemical mechanical polishing. Chemical mechanical polishing is a processing technology that combines mechanical polishing and chemical etching, and is usually used for global flattening to obtain a flat surface. In the process of chemical mechanical polishing, it is usually necessary to use a grinding disc to mechanically grind the substrate to be polished, and at the same time add a grinding liquid for chemical etching.

[0072] It is understood that the grinding liquid used in the first grinding process should be able to etch the conductive layer 130. Furthermore, the etching rate of the conductive layer 130 by the grinding liquid used in the first grinding process is greater than the etching rate of the blocking layer 120.

[0073] As some examples of this embodiment, the polishing liquid used in the first polishing process includes one or more of amorphous silicon dioxide, hydrogen peroxide, water, a corrosion inhibitor, and a barrier layer 120 inhibitor.

[0074] Step S3 , performing a second grinding process on the conductive layer 130 after the first grinding process.

[0075] Figure 4 For Figure 3 The schematic diagram of the structure after the second grinding process is performed on the structure shown in FIG. Figure 3 and Figure 4 As shown, after the second grinding process, the conductive layer 130 is further thinned, and accordingly, a depression is generated on its surface.

[0076] There is a certain degree of unevenness in the actual grinding process, which may result in that during the first grinding process, part of the conductive layer 130 on the surface of the substrate to be ground has been ground away to expose the barrier layer 120, while another part of the conductive layer 130 has not been completely ground to expose the barrier layer 120. The second grinding process set in this embodiment is a process of over-grinding the conductive layer 130 to ensure that all of the conductive layer 130 is ground to expose the barrier layer 120. However, if Figure 4 As shown, over-grinding may also cause certain depressions on the surface of the remaining conductive layer 130 .

[0077] As some examples of this embodiment, the second polishing process is performed by chemical mechanical polishing.

[0078] As some examples of this embodiment, the polishing liquid used in the second polishing process includes amorphous silicon dioxide, hydrogen peroxide, water, a corrosion inhibitor and a barrier layer 120 inhibitor.

[0079] As some examples of this embodiment, the second grinding process can be performed immediately after the first grinding process. That is, after the first grinding process, no other grinding process is performed, and the second grinding process is directly started. Further, the grinding liquid used in the first grinding process is the same as the grinding liquid used in the second grinding process. This allows the first grinding process and the second grinding process to be actually performed and completed in the same process, and there is no need to replace the grinding liquid.

[0080] As some examples of this embodiment, the time of the second grinding process is controllable, so that after the second grinding process, the height difference between the bottom end of the conductive layer 130 and the surface of the barrier layer 120 (ie, the degree of depression of the conductive layer 130) is controllable.

[0081] As some examples of this embodiment, after the second grinding process, the height difference between the bottom end of the conductive layer 130 and the top surface of the barrier layer 120 is 0 nm to 50 nm.

[0082] In step S4 , a third grinding process is performed on the barrier layer 120 and the conductive layer 130 , and the third grinding process stops at the surface of the insulating layer 110 .

[0083] Figure 5 For Figure 4 The schematic diagram of the structure after the third grinding process is performed on the structure shown in FIG. Figure 4 and Figure 5 As shown, during the third grinding process, the barrier layer 120 is removed to expose the insulating layer 110 thereunder, and a portion of the conductive layer 130 is also removed, so that the conductive layer 130 is further thinned.

[0084] In this embodiment, the insulating layer 110 serves as a stop layer for the third grinding process, that is, the third grinding process is stopped when grinding to the insulating layer 110. The third grinding process may be performed in an endpoint control mode.

[0085] As some examples of this embodiment, the third polishing process is performed by chemical mechanical polishing.

[0086] It can be understood that the grinding liquid used in the third grinding process should be able to etch the barrier layer 120 and the conductive layer 130. Further, the etching rate of the grinding liquid used in the third grinding process for the barrier layer 120 is greater than the etching rate of the conductive layer 130, which makes the thinning amount of the conductive layer 130 less than the thinning amount of the barrier layer 120, so that when the barrier layer 130 is completely removed, a relatively thick conductive layer 130 is retained, so that the conductive layer 130 is easier to form a flat or convex conductive plug 131 in the subsequent etching process.

[0087] As some examples of this embodiment, the polishing liquid used in the third polishing process includes one or more of amorphous silicon dioxide, hydrogen peroxide, water, a corrosion inhibitor, and a barrier layer inhibitor.

[0088] It can be understood that, since the over-grinding has been completed in the second grinding process, the third grinding process can be stopped directly at the insulating layer 110, and there is no need to perform over-grinding on the conductive layer 130 thereafter, which can prevent the further deepening of the surface depression of the conductive layer 130. Therefore, compared with the conventional technology, the embodiment of the present disclosure can improve the depression degree of the conductive layer 130.

[0089] In step S5 , a fourth grinding process is performed on the insulating layer 110 and the conductive layer 130 .

[0090] Figure 6 For Figure 5 A schematic diagram of a structure after the insulating layer 110 and the conductive layer 130 are subjected to a fourth grinding process based on the structure shown in FIG. Figure 5 and Figure 6 As shown, during the fourth grinding process, the insulating layer 110 and the conductive layer 130 are both removed, so that the insulating layer 110 and the conductive layer 130 are both thinned.

[0091] As some examples of this embodiment, during the fourth grinding process, after the insulating layer 110 is thinned to a preset target thickness, the fourth grinding process is stopped and the remaining conductive layer 130 in the plug hole can serve as a conductive plug 131 .

[0092] As some examples of this embodiment, the mode used in the step of performing the fourth grinding process is process control feedback, and the polishing time is dynamically controlled according to the thickness of the insulating layer 110 before the fourth grinding process, so that the thinned insulating layer 110 reaches a preset target thickness. Process control feedback (Advanced Process Control Feedback, APC Feedback) is a process control strategy for real-time monitoring and dynamic adjustment of the grinding process to ensure highly consistent and repeatable polishing results. Process control feedback usually involves the use of sensors and control systems to monitor key parameters such as material removal rate, surface roughness, temperature, etc. in the grinding process in real time, and automatically adjust grinding parameters such as grinding pressure, polishing liquid flow, rotation speed, etc. based on these feedback information. In the process of the fourth grinding process, the process control feedback mode is adopted, which can not only accurately control the insulating layer 110 to be ground to the target thickness, but also can simultaneously correct the depressions formed on the surface of the conductive layer 130 during the second polishing process and the third polishing process, thereby playing a role in improving the depressions.

[0093] As some examples of this embodiment, after the fourth grinding process, the top of the conductive layer 130 is higher than or equal to the top of the insulating layer 110. By setting the top of the conductive layer 130 to be higher than or equal to the top of the insulating layer 110, it is possible to more effectively avoid exposing the gap in the conductive layer 130, thereby ensuring the formation of a conductive plug 131 with good quality.

[0094] As some examples of this embodiment, in the step of performing the fourth grinding process on the insulating layer 110 and the conductive layer 130, the thinning rate of the conductive layer 130 is controlled to be smaller than the thinning rate of the insulating layer 110. It can be understood that the thinning rate can be controlled by selecting an appropriate grinding liquid. The time of the conductive layer 130 and the insulating layer 110 in the fourth grinding process is the same, so that the thinning rate of the conductive layer 130 is smaller than the thinning rate of the insulating layer 110, which can ensure that the final thinning amount of the conductive layer 130 is small.

[0095] In the embodiment of the present disclosure, the main purpose of the second grinding process is to perform a certain amount of over-grinding on the conductive layer 130. Compared with the over-grinding process during the removal of the barrier layer 120, by arranging the second grinding process before the third grinding process, that is, before the barrier layer 120 is removed, the thinning amount of the conductive layer 130 during over-grinding is more controllable, thereby avoiding the conductive layer 130 from forming an excessively deep depression. This will be conducive to achieving the top of the conductive layer 130 being higher than or equal to the top of the insulating layer 110 during the fourth grinding process.

[0096] Further, as some examples of this embodiment, according to the initial thickness of the insulating layer 110, the time of the second grinding process is correspondingly controlled so that the top of the conductive layer 130 is higher than or equal to the top of the insulating layer 110. In this embodiment, based on existing or known conditions, by controlling the time of the second grinding process, the thinning amount of the conductive layer 130 or the depression amount of the conductive layer 130 during the second grinding process can be dynamically controlled, and then the protrusion degree of the conductive layer 130 when the insulating layer 110 is ground to the target thickness can be accurately controlled. The specific analysis is as follows.

[0097] For ease of explanation, Figure 7 A schematic diagram showing the thickness variation of each layer during step S1 to step S5 is shown. Figure 8 for Figure 7 Schematic diagram of the enlarged structure of area A in the middle.

[0098] Reference Figure 7 and Figure 8 As shown, before the first grinding process, the initial thickness of the insulating layer 110 in the substrate to be ground is H 0 The target thickness of the insulating layer 110 remaining after the fourth grinding process is preset to be H TSince the insulating layer 110 is thinned only during the fourth grinding process, the thinning amount of the insulating layer 110 during the fourth grinding process is H. 0 -H T .

[0099] Reference Figure 7 and Figure 8 As shown, after the third grinding process, the height difference between the bottom end of the conductive layer 130 and the top surface of the insulating layer 110 is H C3 During the fourth grinding process, the conductive layer 130 is reduced by an amount of H C4 After the fourth grinding process, if it is necessary to obtain a conductive layer 130 whose top is higher than or equal to the insulating layer 110, H 0 , H C3 , H C4 and H T The following formula (1) should be satisfied.

[0100] (1)

[0101] It can be understood that in formula (1), when the equal sign holds, the conductive layer 130 retained after the fourth grinding process is flush with the top of the insulating layer 110, and a conductive plug 131 with a flat surface can be formed. When the less than sign holds, the top of the conductive layer 130 retained after the fourth grinding process is higher than the top of the insulating layer 110, and a conductive plug 131 with a raised surface can be formed.

[0102] Reference Figure 7 and Figure 8 As shown, after the first grinding process and before the second grinding process, the thickness of the barrier layer 120 is H B After the second grinding process and before the third grinding process, the height difference between the bottom end of the conductive layer 130 and the top surface of the barrier layer 120 is H C1 During the third grinding process, the conductive layer 130 is reduced by an amount of H C2 Then H C3 , H B , H C1 and H C2 The following formula (2) is satisfied.

[0103] (2)

[0104] Combining equation (1) and equation (2), we can easily obtain equation (3).

[0105] (3)

[0106] Furthermore, when the grinding conditions such as the grinding liquid used are determined, the thinning rate of the material being ground in each grinding process is also determined accordingly. In this embodiment, the thinning rate of the conductive layer 130 in the second grinding process is R C1 The thinning rate of the conductive layer 130 during the third grinding process is R C2 , the thinning rate of the conductive layer 130 during the fourth grinding process is R C4 The thinning rate of the barrier layer 120 during the third grinding process is R B The thinning rate of the insulating layer 110 during the fourth grinding process is R T It can be understood that each thinning rate can be obtained through actual measurement.

[0107] According to the above parameters, it is easy to obtain: the time required for the second grinding process T 2 =H C1 / R C1 The time required for the third grinding process is T 3 =H B / R B , while T 3 =H C2 / R C2 The time required for the fourth grinding process is T 4 =(H 0 -H T ) / R T , while T 4 =H C4 / R C4 Then, according to formula (3), we can further arrange it into the following formula (4).

[0108] (4)

[0109] That is, when equation (4) is satisfied, the conductive layer 130 can be obtained with its top higher than or equal to the insulating layer 110. In equation (4), each thinning rate R C1 , R C2 , R C4 , R B and R T The thickness H of the barrier layer 120 is related to the polishing liquid used and is usually a certain amount. B Usually a certain amount, target thickness H T The initial thickness H of the insulating layer 110 in the substrate to be ground is usually set according to actual needs. 0 and the time T of the second grinding process 2 According to the initial thickness H of the insulating layer 110 0 , corresponding to the time T of the second grinding process 2, and the relationship between the two satisfies equation (4), that is, the top of the conductive layer 130 can be higher than or equal to the top of the insulating layer 110 .

[0110] The preparation method of steps S1 to S5 has at least the following effects.

[0111] First, by controlling the time of the second grinding process, the thinning amount of the conductive layer 130 during the second grinding process can be dynamically controlled, so that the grinding amount of the conductive layer 130 is more controllable.

[0112] Furthermore, the second grinding process is used as over-grinding of the conductive layer 130 , and no over-grinding process is required after the third grinding process, which can improve the concavity of the conductive layer 130 .

[0113] Furthermore, the fourth grinding process using the process control feedback mode can accurately control the insulating layer 110 to reach the target thickness, and can correct the surface depression of the conductive layer 130 during the second grinding process to the third grinding process, so as to more accurately control the protrusion of the final conductive plug 131.

[0114] Furthermore, when other parameters are kept constant, the time of the second grinding process is adjusted accordingly according to the initial thickness of the insulating layer 110 , so that a flat or convex conductive plug 131 can be obtained conveniently and accurately.

[0115] In a second aspect, the present disclosure also provides a method for preparing a semiconductor device, which comprises the following steps: sequentially preparing an insulating layer 110, a barrier layer 120 and a conductive layer 130 on a functional structure as a substrate to be ground; and preparing a conductive plug 131 in the substrate to be ground using the method for preparing the conductive plug 131 of the above embodiment.

[0116] In a third aspect, the present disclosure further provides a semiconductor device, which is manufactured by the above-mentioned method for manufacturing a semiconductor device; or, the semiconductor device includes a conductive plug 131 manufactured by the method for manufacturing a conductive plug 131 of any of the above-mentioned embodiments.

[0117] Please note that the above embodiments are for illustrative purposes only and are not meant to be limiting of this document.

[0118] It should be understood that, unless otherwise specified herein, there is no strict order restriction for the execution of the steps, and the steps may be executed in other orders. Moreover, at least a portion of the steps in the preparation process may include multiple sub-steps or multiple stages, and these sub-steps or stages are not necessarily executed at the same time, but may be executed at different times, and the execution order of these sub-steps or stages is not necessarily sequential, but may be executed in turn or alternately with other steps or at least a portion of the sub-steps or stages of other steps.

[0119] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0120] The technical features of the above embodiments may be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

Claims

1. A method for preparing a conductive plug, characterized in that: The steps include: Providing a substrate to be polished, the substrate to be polished comprising an insulating layer, a barrier layer and a conductive layer, the insulating layer having a plug hole, the barrier layer being arranged on the top surface of the insulating layer and extending to cover the hole wall of the plug hole, and the conductive layer being arranged on the barrier layer; Performing a first grinding process on the conductive layer, wherein the first grinding process stops at a surface of the barrier layer; performing a second grinding process on the conductive layer after the first grinding process; Performing a third grinding process on the barrier layer and the conductive layer, wherein the third grinding process stops at a surface of the insulating layer; The insulating layer and the conductive layer are subjected to a fourth grinding process.

2. The method for preparing a conductive plug according to claim 1, characterized in that: After the fourth grinding process, the top of the conductive layer is higher than or equal to the top of the insulating layer.

3. The method for preparing a conductive plug according to claim 2, characterized in that: In the step of performing the fourth grinding process on the insulating layer and the conductive layer, a thinning rate of the conductive layer is controlled to be smaller than a thinning rate of the insulating layer.

4. The method for preparing a conductive plug according to claim 2, characterized in that: After the third grinding process, the height difference between the bottom end of the conductive layer and the top surface of the insulating layer is H C3 During the fourth grinding process, the conductive layer is reduced by H C4 ; where H C3 With H C4 The sum is less than the thinning amount of the insulating layer during the fourth grinding process.

5. The method for preparing a conductive plug according to claim 4, characterized in that: The time of the second grinding process is controlled accordingly according to the initial thickness of the insulating layer, so that the top of the conductive layer is higher than or equal to the top of the insulating layer.

6. The method for preparing a conductive plug according to claim 5, characterized in that: Before the first grinding process, the initial thickness of the insulating layer is H0, and the preset target thickness of the insulating layer retained after the fourth grinding process is H T After the first grinding process and before the second grinding process, the thickness of the barrier layer is H B The time required for the second grinding process is T2, and the thinning rate of the conductive layer during the second grinding process is R C1 The thinning rate of the conductive layer during the third grinding process is R C2 The thinning rate of the conductive layer during the fourth grinding process is R C4 The thinning rate of the barrier layer during the third grinding process is R B The thinning rate of the insulating layer during the fourth grinding process is R T , where each parameter satisfies the following relationship: .

7. The method for preparing a conductive plug according to any one of claims 1 to 6, characterized in that: After the second grinding process, the height difference between the bottom end of the conductive layer and the top surface of the barrier layer is 0 nm to 50 nm.

8. The method for preparing a conductive plug according to any one of claims 1 to 6, characterized in that: The mode used in the step of performing the fourth grinding treatment is process control feedback, and the polishing time is dynamically controlled according to the thickness of the insulating layer before the fourth grinding treatment, so that the insulating layer after thinning reaches a preset target thickness.

9. The method for preparing a conductive plug according to any one of claims 1 to 6, characterized in that: The material of the insulating layer is selected from one or more of silicon nitride, silicon carbide, silicon dioxide, silicon oxynitride and black diamond; and / or, The material of the conductive layer is selected from one or more of tungsten, aluminum, copper, gold and silver; and / or, The material of the barrier layer is selected from one or more of titanium nitride, tantalum nitride, titanium, tantalum and titanium-tungsten alloy.

10. The method for preparing a conductive plug according to any one of claims 1 to 6, characterized in that: The second grinding process is performed immediately after the first grinding process, and the grinding liquid used in the first grinding process is the same as the grinding liquid used in the second grinding process.

11. The method for preparing a conductive plug according to any one of claims 1 to 6, characterized in that: The polishing liquid used in the first polishing process comprises one or more of amorphous silicon dioxide, hydrogen peroxide, water, a corrosion inhibitor and a barrier layer inhibitor; and / or, The polishing liquid used in the second polishing treatment comprises one or more of amorphous silicon dioxide, hydrogen peroxide, water, a corrosion inhibitor and a barrier layer inhibitor; and / or, The polishing liquid used in the third polishing process comprises one or more of amorphous silicon dioxide, hydrogen peroxide, water, a corrosion inhibitor and a barrier layer inhibitor; and / or, The grinding liquid used in the fourth grinding process includes one or more of amorphous silicon dioxide, hydrogen peroxide, water, citric acid and a chelating agent.

12. A method for preparing a semiconductor device, characterized in that: The steps include: An insulating layer, a barrier layer and a conductive layer are sequentially prepared on the functional structure as a substrate to be polished; A conductive plug is prepared in the substrate to be ground using the method for preparing a conductive plug as described in any one of claims 1 to 11.

13. A semiconductor device, characterized in that: Prepared by the method for preparing a semiconductor device according to claim 12; or, The semiconductor device includes a conductive plug prepared by the conductive plug preparation method according to any one of claims 1 to 11.

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