Manufacturing method of metal through hole and semiconductor structure

Abstract

The invention discloses a manufacturing method of a metal through hole and a semiconductor structure, and the method comprises the steps: executing a first plasma etching technology with a mask, and carrying out the periodic etching of the surface of a substrate, and forming a first through hole; a maskless second plasma etching process is executed, the first through hole is etched into a second through hole, the second plasma etching process sequentially comprises a first etching stage, a second etching stage and a third etching stage, the first etching stage is used for forming a side wall notch in the top of the first through hole, and the second etching stage is used for forming a side wall notch in the top of the second through hole; the second etching stage is used for smoothening the top morphology and the side wall, and the third etching stage is used for forming a second through hole which is larger than the opening width of the first through hole and smaller than the inclination angle of the side wall; and filling the formed second through hole to form a metal through hole. According to the manufacturing method, the through hole with a small inclination angle can be manufactured, the defect of incomplete filling can be avoided, and the requirements of a high-performance device for electrical connection, heat dissipation and the like are met.

Description

Technical Field

[0001] The present application relates to the field of semiconductor processing technology, and in particular to a method for manufacturing a metal through hole and a semiconductor structure. Background Art

[0002] With the development of electronic devices, silicon-based materials are increasingly being used, particularly in high-performance integrated circuits, microelectromechanical systems (MEMS), image sensors, and power electronics. Through-hole (Via) technology plays a crucial role in these devices, enabling electrical connections between multi-layer circuits, thermal management, and light transmission. To improve device performance, especially in high-power and high-density integrated circuits, higher requirements are being placed on the structure and filling of VIAs.

[0003] Currently, traditional through-hole (VH) deep silicon etching methods mostly use vertical hole wall designs. However, with the miniaturization of device critical dimensions and the increase in aspect ratios, this design may cause problems in some applications, such as incomplete filling, poor heat dissipation, and unstable electrical connections. Therefore, it is necessary to develop a new metal via fabrication method that can meet high performance requirements while overcoming these shortcomings of existing technologies. Summary of the Invention

[0004] The purpose of this application is to overcome the above-mentioned problems existing in the prior art and to provide a method for manufacturing a metal through hole and a semiconductor structure, which can meet high performance requirements while overcoming the problems existing in the prior art such as incomplete filling, poor heat dissipation performance, and unstable electrical connection.

[0005] To achieve the above objectives, the technical solutions of this application are as follows: According to a first aspect of the present application, an embodiment of the present application provides a method for manufacturing a metal through hole, comprising: Performing a first plasma etching process with a mask to periodically etch a surface of one side of the substrate to form a first through hole in the substrate, wherein the first through hole has a first opening width and a first sidewall inclination angle; performing a maskless second plasma etching process to etch the sidewall of the first through hole to form the second through hole; the second plasma etching process comprises a first etching stage, a second etching stage, and a third etching stage connected in sequence, wherein the first etching stage uses a first etching gas and a first pressure to form a sidewall notch at the top of the first through hole, the second etching stage uses a second etching gas and a second pressure to round the top morphology of the sidewall notch and smooth the sidewall of the first through hole, and the third etching stage uses a third etching gas and a third pressure to form the second through hole having a second orifice width and a second sidewall inclination angle; the second orifice width is greater than the first orifice width, and the second sidewall inclination angle is less than the first sidewall inclination angle; the first etching gas, the second etching gas, and the third etching gas are different, and the first pressure, the second pressure, and the third pressure increase in sequence; The second through hole is filled with metal to form a metal through hole.

[0006] In some embodiments, the sidewall notch has a third sidewall inclination angle, and the third sidewall inclination angle is smaller than the second sidewall inclination angle.

[0007] In some embodiments, the sidewall of the first through hole has a first roughness, and the sidewall of the second through hole has a second roughness. When performing the second etching stage, the second roughness is made smaller than the first roughness by rounding the top morphology of the sidewall notch and smoothing the sidewall of the first through hole.

[0008] In some embodiments, the first etching gas includes an oxidizing gas.

[0009] In some embodiments, the second etching gas includes an oxidizing gas and a carbon-fluorine gas.

[0010] In some embodiments, the third etching gas includes sulfur-fluorine gas and carbon-fluorine gas.

[0011] In some embodiments, the first pressure is 8 mtorr to 50 mtorr.

[0012] In some embodiments, the second pressure is 10 mtorr to 100 mtorr.

[0013] In some embodiments, the third pressure is 110 mtorr to 200 mtorr.

[0014] In some embodiments, when performing the first etching stage, the bias power is 10W to 100W, and the time is 3s to 12s.

[0015] In some embodiments, when performing the second etching stage, the bias power is 0W to 90W, and the time is 3s to 12s.

[0016] In some embodiments, when performing the third etching stage, the bias power is 0W to 100W, and the time is 5s to 100s.

[0017] In some embodiments, the first etching gas includes O 2 with a flow rate of 1 sccm to 200 sccm.

[0018] In some embodiments, the second etching gas includes O2 and CF4, the flow rate of O2 is 1 sccm to 200 sccm, and the flow rate of CF4 is 1 sccm to 150 sccm.

[0019] In some embodiments, the third etching gas includes SF6 and C4F8, the flow rate of SF6 is 1 sccm to 200 sccm, and the flow rate of C4F8 is 1 sccm to 200 sccm.

[0020] In some embodiments, the inclination angle of the first sidewall is 88 degrees to 89 degrees.

[0021] In some embodiments, the inclination angle of the second sidewall is 80 degrees to 87 degrees.

[0022] In some embodiments, the inclination angle of the third sidewall is 4 degrees to 20 degrees.

[0023] In some embodiments, the substrate material includes silicon.

[0024] In some embodiments, the metal filled in the second via hole includes copper or tungsten.

[0025] In some embodiments, the first plasma etching process includes periodic cycle steps formed by a deposition step and an etching step in sequence. The process gas used in the deposition step includes C4F8, and the process gas used in the etching step includes SF6. The first through hole is formed by alternately using C4F8 to deposit a passivation layer and using SF6 for etching.

[0026] In some embodiments, the second through hole has a sidewall shape that is inclined and curved inward from top to bottom.

[0027] According to the second aspect of the present application, an embodiment of the present application further provides a semiconductor structure comprising a metal via, wherein the metal via is obtained using the method for manufacturing a metal via provided in any one of the embodiments of the first aspect above.

[0028] The embodiments of the present application may or at least have the following advantages: (1) The present application forms a through hole (second through hole) structure with a desired inclination angle (second sidewall inclination angle) by performing the first plasma etching process and the second plasma etching process in stages. The first plasma etching process can be used to achieve accurate through hole depth, thereby ensuring the stability and uniformity of the etching depth, while ensuring a reasonable balance between the etching rate and the selectivity, avoiding the problem of uneven depth and width, and providing a stable benchmark for subsequent processes. On this basis, the second plasma etching process is performed and further subdivided into three connected stages (the first The process comprises the following steps: the first etching stage, the second etching stage, and the third etching stage), which can effectively improve the smoothness of the top of the through-hole, ensure that the hole mouth has no sharp corners, and repair the roughness of the side wall to achieve the ideal surface quality. It can also produce a through-hole with a smaller tilt angle (an inverted trapezoidal or trumpet-shaped second through-hole), thereby improving the shortcomings of the traditional single etching process in making inclined through-holes (such as large hole wall roughness and top morphology defects), providing higher flexibility and precision, and thus meeting the requirements for the through-hole tilt angle in different applications, thereby meeting the needs of high-performance devices for electrical connection and heat dissipation.

[0029] (2) This application provides a complete set of efficient manufacturing processes for tapered through-holes with tilt angles, which solves many challenges in depth, morphology, tilt angle, etc., so that during the metal filling process, the improved second through-hole etching structure can better control the filling effect, avoid defects such as incomplete filling (such as the appearance of voids), and significantly improve the performance and reliability of the filled metal through-holes.

[0030] (3) This application not only overcomes the limitation of the traditional single etching process that cannot achieve high-precision control, but also provides a more sophisticated and controllable metal through-hole etching solution for the manufacture of high-performance devices.

[0031] Other advantages of the present application will be described in the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 This is a flow chart of a method for manufacturing a metal through hole according to a preferred embodiment of the present application.

[0033] Figure 2 A schematic diagram of a structure after a mask is formed on a substrate is provided in a preferred embodiment of the present application.

[0034] Figure 3 A schematic structural diagram of a preferred embodiment of the present application after a first through hole is formed on a substrate.

[0035] Figure 4 A schematic diagram of a structure after removing the mask is provided in a preferred embodiment of the present application.

[0036] Figure 5 A schematic diagram of a structure after a sidewall notch is formed at the top of a first through hole provided in a preferred embodiment of the present application.

[0037] Figure 6 A schematic diagram of a structure after the top morphology of a sidewall notch is rounded and the sidewall of a first through hole is smoothed, provided in a preferred embodiment of the present application.

[0038] Figure 7 A schematic structural diagram of a preferred embodiment of the present application after a second through hole is formed on a substrate.

[0039] Figure 8 A schematic diagram of a structure after a metal through hole is formed on a substrate is provided in a preferred embodiment of the present application.

[0040] Figure 9 An electron microscope schematic diagram of a second through hole provided in a preferred embodiment of the present application.

[0041] Figure 10 This is an electron microscope schematic diagram of a traditional through hole A provided for comparative example 1.

[0042] Figure 11 A schematic diagram of a traditional through hole B provided for comparative example 2.

[0043] In the figure, 10. substrate; 11. mask; 12. opening; 13. first through hole; 14. scallop pattern; 15. sidewall notch; 16. second through hole; 17. metal through hole. DETAILED DESCRIPTION

[0044] In order to solve the problems of incomplete through-hole filling, poor heat dissipation performance, unstable electrical connection, etc. existing in the vertical through-hole manufactured using traditional processes in the prior art, the embodiment of the present application provides a method for manufacturing a metal through-hole, comprising: Performing a first plasma etching process with a mask to periodically etch a surface of one side of the substrate to form a first through hole in the substrate, wherein the first through hole has a first opening width and a first sidewall inclination angle; performing a maskless second plasma etching process to etch the sidewall of the first through hole to form the second through hole; the second plasma etching process comprises a first etching stage, a second etching stage, and a third etching stage connected in sequence, wherein the first etching stage uses a first etching gas and a first pressure to form a sidewall notch at the top of the first through hole, the second etching stage uses a second etching gas and a second pressure to round the top morphology of the sidewall notch and smooth the sidewall of the first through hole, and the third etching stage uses a third etching gas and a third pressure to form the second through hole having a second orifice width and a second sidewall inclination angle; the second orifice width is greater than the first orifice width, and the second sidewall inclination angle is less than the first sidewall inclination angle; the first etching gas, the second etching gas, and the third etching gas are different, and the first pressure, the second pressure, and the third pressure increase in sequence; The second through hole is filled with metal to form a metal through hole.

[0045] The through-hole (second through-hole) manufactured by the embodiment of the present application has a specific tilt angle, providing greater flexibility and precision. The smoothness of the top wall and the roughness of the sidewall are controlled by an improved etching process, which can meet the requirements of electrical connection and thermal management in high-performance electronic devices. The embodiment of the present application not only overcomes the limitations of the traditional single etching process and solves challenges in depth, morphology, tilt angle, etc., but also provides a more refined and controllable etching scheme for the manufacture of high-performance devices, significantly improving the performance and reliability of metal through-holes.

[0046] The specific implementation methods of this application are described in detail below with reference to the accompanying drawings.

[0047] refer to Figure 1 The embodiment of the present application provides a method for manufacturing a metal through hole, which comprises the following steps in sequence: Step S11: providing a substrate.

[0048] refer to Figure 2 In some embodiments, the material of the substrate 10 includes silicon, that is, the substrate 10 is a silicon substrate.

[0049] In some embodiments, a silicon wafer may be used as the substrate 10 to further form a desired through-hole etching structure on the substrate 10 .

[0050] In some embodiments, the silicon wafer may be doped to provide the substrate 10 with desired electrical properties.

[0051] In some embodiments, integrated circuits, such as transistor structures, etc., can be fabricated on the substrate 10 to achieve desired vertical interconnections through the metal vias formed by filling the metal after forming the vias (second vias).

[0052] Step S12: Forming a plurality of masks on the surface of the substrate.

[0053] Reference Figure 2 In some embodiments, a photoresist layer is spin-coated on the upper surface of the substrate 10 as a mask layer. A photolithography process is performed on the photoresist layer to form a plurality of photoresist patterns on the upper surface of the substrate 10, and the photoresist patterns are used as the masks 11. Any two adjacent masks 11 have an opening 12 therebetween as an etching window.

[0054] It should be noted that Figure 2 In the above embodiment, only the case where three masks 11 are formed on the upper surface of the substrate 10 is shown. However, it should be understood that other different numbers of masks, such as two masks, four masks, five masks, ten masks, etc., can be formed on the upper surface of the substrate 10, and the number of masks is not limited to the above.

[0055] Step S13: Performing a first plasma etching process and periodically and cyclically etching the exposed surface of the substrate through the masks to form first vias in the substrate.

[0056] Reference Figure 3 In some embodiments, when the first plasma etching process is performed, the upper surface of the substrate 10 exposed within the opening 12 is periodically and cyclically etched downward through the masks 11 formed in the previous step to form the first vias 13 in the substrate 10 on the upper surface of the substrate 10 exposed within the opening 12. That is, the first plasma etching process with masks is performed to etch the upper surface of the substrate 10 exposed within the opening 12 downward and form the first vias 13.

[0057] In some embodiments, before performing the first plasma etching process, the substrate 10 is pre-etched to open the upper surface of the substrate 10. That is, the bottom of the opening 12 is pre-etched downward through the masks 11 formed in the previous step to expose the upper surface of the substrate 10 on the bottom of the opening 12, so that when the first plasma etching process is subsequently performed, the upper surface of the substrate 10 exposed within the opening 12 can be periodically and cyclically etched downward.

[0058] In some embodiments, the first plasma etching process includes a periodic cycle of steps, sequentially followed by a deposition step and an etching step. Specifically, each cycle includes a deposition step and an etching step, which are repeated, thereby forming a periodic cyclic etching process. The deposition step forms a passivation layer (polymer) that protects the sidewalls and mask 11. During the deposition step, the passivation layer is deposited on the inner walls of the first through-hole 13 being formed and on the surface of the mask 11. The etching step first etches open the passivation layer at the bottom of the first through-hole 13 being formed, and then continues etching downward through the substrate 10 to a depth of one unit. During the etching step, the passivation layer on the sidewalls of the first through-hole 13 being formed and on the surface of the mask 11 is also etched away. In the next deposition step, the passivation layer is again deposited on the inner wall of the first through-hole 13 being formed and on the surface of the mask 11, thereby continuously protecting the sidewalls and the mask 11. The etching step in this cycle will again etch open the new passivation layer at the bottom of the first through-hole 13 being formed, and then continue to etch downward to a unit depth of the substrate 10. By repeating the above process and periodically etching the substrate 10, a first through-hole 13 of a predetermined depth and having a vertical (or substantially vertical) orientation can be formed in the substrate 10.

[0059] It should be noted that during the first plasma etching process, the etching step in each cycle etches the substrate 10 isotropically. Due to repeated passivation deposition, periodic scallop-like ripples, i.e., scallop patterns 14, inevitably form on the sidewalls. This increases the roughness of the sidewalls and thus affects the metal filling quality. Therefore, this can be addressed and improved in subsequent steps.

[0060] The sidewall of the first through hole 13 formed by the first plasma etching process has a first roughness.

[0061] The first through-hole 13 formed by the first plasma etching process has a first opening width m and a first sidewall inclination angle. The first opening width m is the width of the top opening of the first through-hole 13. The first sidewall inclination angle is a first angle α between the sidewall of the first through-hole 13 and the horizontal cross-sectional direction of the first through-hole 13, which is directed outward.

[0062] In some embodiments, when performing the first plasma etching process, the process gas used in the deposition step includes C4F8, and the process gas used in the etching step includes SF6. By alternately using C4F8 to deposit the passivation layer and using SF6 to etch, a first through hole 13 having a first opening width m, a first sidewall inclination angle, and a first sidewall roughness is formed.

[0063] In some embodiments, during the first plasma etching process, the C4F8 deposition step may have a flow rate of 1 sccm to 1000 sccm. For example, the flow rate may be 1 sccm, 5 sccm, 10 sccm, 50 sccm, 100 sccm, 500 sccm, 700 sccm, or 1000 sccm, or any value between any two of the aforementioned flow rates. The flow rate range is not limited to this.

[0064] In some embodiments, when performing the first plasma etching process, the SF6 flow rate used in the etching step is 1 sccm to 1000 sccm. For example, the flow rate can be 1 sccm, 4 sccm, 8 sccm, 20 sccm, 60 sccm, 100 sccm, 500 sccm, or 1000 sccm, or any value between any two of the aforementioned flow rates. The flow rate range is not limited to this.

[0065] In some embodiments, an inert gas may be used as a carrier gas during the first plasma etching process. For example, argon (Ar) may be used as a carrier gas with a flow rate of 1 sccm to 500 sccm. For example, the flow rate may be 1 sccm, 3 sccm, 6 sccm, 15 sccm, 40 sccm, 90 sccm, 200 sccm, or 500 sccm, or any value between any two of the aforementioned flow rates. The flow rate range is not limited to this.

[0066] In some embodiments, the temperature during the first plasma etching process is 10° C. to 60° C. For example, the temperature may be 10° C., 10.1° C., 11° C., 22° C., 28° C., 35° C., 36° C., 44° C., 49° C., 59° C., or 60° C., or any value between any two of the foregoing temperature values. The temperature range is not limited thereto.

[0067] In some embodiments, during the first plasma etching process, the pressure is between 1 mtorr and 100 mtorr. For example, the pressure can be 1 mtorr, 1.2 mtorr, 5 mtorr, 10 mtorr, 20 mtorr, 25 mtorr, 30 mtorr, 50 mtorr, 80 mtorr, or 100 mtorr, or any value between any two of the aforementioned pressure values. The pressure range is not limited to this.

[0068] In some embodiments, when performing the first plasma etching process, the source power is 100 W to 3000 W. For example, the source power can be 100 W, 200 W, 500 W, 800 W, 1000 W, 1500 W, 2000 W, 2500 W, or 3000 W, or any value between any two of the aforementioned source power values. The source power range is not limited to this.

[0069] In some embodiments, when performing the first plasma etching process, the bias power is 10 W to 200 W. For example, the bias power can be 10 W, 20 W, 30 W, 50 W, 80 W, 100 W, 130 W, 150 W, 190 W, or 200 W, or any value between any two of the foregoing bias power values. The bias power range is not limited to this.

[0070] In some embodiments, during the first plasma etching process, while maintaining a balance between the deposition and etching steps, the amount of lateral etching of the substrate 10 is gradually reduced in each cycle, resulting in an overall tapered etched profile. This etching method can also reduce the prominence of the sidewall scallops 14 to a certain extent, resulting in a relatively smooth sidewall surface. The amount of lateral etching can be controlled by adjusting the etching step duration in each cycle.

[0071] In some embodiments, the inclination angle of the first sidewall of the first through hole 13 is 88 degrees to 89 degrees, but is not limited thereto (may be slightly less than 88 degrees or slightly greater than 89 degrees).

[0072] In some embodiments, the first roughness of the sidewall of the first through hole 13 is approximately 30 nm to 50 nm, but is not limited thereto.

[0073] In some embodiments, the aspect ratio of the first through hole 13 is greater than 3:1, or greater than 5:1, or greater than 10:1, but is not limited thereto.

[0074] Step S14: removing the mask.

[0075] refer to Figure 4 In some embodiments, a dry ashing process (asher process) is used to remove the photoresist, that is, to completely remove the photoresist pattern serving as mask 11. After removing the photoresist pattern (mask 11), the entire upper surface of substrate 10 is completely exposed, that is, the upper surface of substrate 10 on both sides of first through hole 13 is no longer protected by mask 11.

[0076] In some embodiments, when a dry ashing process is used to remove the photoresist pattern serving as the mask 11 , the process gas used includes at least one of O 2 , a mixed gas of H 2 and N 2 , and N 2 , but is not limited thereto.

[0077] Step S15: performing a second plasma etching process to etch the sidewall of the first through hole to etch the first through hole into a second through hole, so that the second through hole has a sidewall inclination angle smaller than that of the first through hole.

[0078] In some embodiments, a second plasma etching process different from the periodic cyclic etching of the first plasma etching process is performed to etch the sidewalls of the first through-hole 13, so as to convert the first through-hole 13 having the first sidewall inclination angle into a second through-hole having the second sidewall inclination angle, and the second through-hole has a sidewall inclination angle smaller than that of the first through-hole 13, i.e., the second sidewall inclination angle is smaller than the first sidewall inclination angle. In other words, the second through-hole has a sidewall that is more inclined relative to the vertical direction (etching direction) than the first through-hole 13. The structure of the formed second through-hole 16 is as follows: Figure 7 The second sidewall inclination angle is a second angle β formed outwardly between the sidewall of the second through hole 16 and the cross-sectional direction (horizontal direction) of the second through hole 16. In this example, both the first angle α and the second angle β are acute angles, and the second angle β is smaller than the first angle α.

[0079] Different from the periodic cyclic etching of the first plasma etching process, the second plasma etching process only includes its own corresponding etching steps, and does not include the deposition step in the first plasma etching process. That is, the second plasma etching process is a non-periodic cyclic etching process.

[0080] In some embodiments, since the mask 11 in the previous step has been completely removed, the second plasma etching process in this step is performed on the upper surface of the substrate 10 under the condition that there is no mask 11 on the upper surface of the substrate 10, that is, the second plasma etching process without mask 11 is performed.

[0081] In some embodiments, the second plasma etching process includes a first etching phase, a second etching phase, and a third etching phase. The first etching phase uses a first etching gas and a first pressure to Figure 5 The top of the first through hole 13 is formed with a sidewall notch 15 (equivalent to a chamfer). The second etching stage uses a second etching gas and a second pressure to round the top morphology of the sidewall notch 15 of the first through hole 13 and smooth the sidewall of the first through hole 13 (refer to Figure 6 The third etching stage uses a third etching gas and a third pressure to form a second through hole 16 having a second opening width n and a second sidewall inclination angle (refer to Figure 7 ).

[0082] In some embodiments, the second opening width n of the second through hole 16 is greater than the first opening width m of the first through hole 13 , and the second sidewall inclination angle of the second through hole 16 is smaller than the first sidewall inclination angle of the first through hole 13 (the second angle β is smaller than the first angle α).

[0083] In some embodiments, the first etching gas, the second etching gas, and the third etching gas are different.

[0084] In some embodiments, the first pressure, the second pressure, and the third pressure increase sequentially.

[0085] refer to Figure 5 In some embodiments, when performing the first etching stage of the second plasma etching process, the first etching gas used includes an oxidizing gas. For example, the first etching gas includes O2, and an inert gas, such as Ar, can be used as a dilution and dissociation gas. Without any mask, the first through hole 13 is etched, and a sidewall notch 15 with a certain tilt angle is formed at the top of the first through hole 13.

[0086] In some embodiments, during the first etching stage, the flow rate of O2 as the first etching gas is 1 sccm to 200 sccm. For example, the flow rate can be 1 sccm, 2 sccm, 5 sccm, 10 sccm, 50 sccm, 100 sccm, 150 sccm, or 200 sccm, or any value between any two of the aforementioned flow rates. The flow rate range is not limited to this.

[0087] In some embodiments, the etching temperature during the first etching stage is 10° C. to 60° C. For example, the temperature can be 10° C., 11° C., 15° C., 20° C., 25° C., 30° C., 40° C., 45° C., 50° C., or 60° C., or any value between any two of the aforementioned temperature values. The temperature range is not limited thereto.

[0088] In some embodiments, during the first etching stage, the first pressure is between 8 mtorr and 50 mtorr. For example, the first pressure can be 8 mtorr, 10 mtorr, 15 mtorr, 20 mtorr, 25 mtorr, 30 mtorr, 40 mtorr, or 50 mtorr, or any value between any two of the aforementioned pressure values. The first pressure range is not limited to this.

[0089] In some embodiments, during the first etching stage, the source power is between 100 W and 3000 W. For example, the source power can be 100 W, 200 W, 500 W, 800 W, 1000 W, 1500 W, 2000 W, 2500 W, or 3000 W, or any value between any two of the aforementioned source power values. The source power range is not limited to this.

[0090] In some embodiments, during the first etching stage, the bias power is between 10 W and 100 W. For example, the bias power can be 10 W, 20 W, 30 W, 40 W, 50 W, 60 W, 70 W, 80 W, 90 W, or 100 W, or any value between any two of the aforementioned bias power values. The bias power range is not limited thereto.

[0091] In some embodiments, the etching time during the first etching stage is 3 seconds to 12 seconds. For example, the time can be 3 seconds, 4 seconds, 5 seconds, 6 seconds, 7 seconds, 8 seconds, 9 seconds, 10 seconds, 11 seconds, or 12 seconds, or any value between any two of the aforementioned time values. The time range is not limited to this.

[0092] After the etching in the first etching stage is performed, a first through hole 13 having a top sidewall notch 15 is formed, that is, a first transition through hole structure is formed. Figure 5 shown.

[0093] In some embodiments, the sidewall notch 15 has a third sidewall inclination angle, which is a third angle θ (i.e., a downward inclination angle of the sidewall notch 15) formed outward between the sidewall (inclined surface) at the notch and the cross-sectional direction (horizontal direction) of the first through hole 13. The third angle θ is an acute angle and is smaller than the second angle β and the first angle α, i.e., the third sidewall inclination angle is smaller than the second and first sidewall inclination angles.

[0094] In some embodiments, the third sidewall inclination angle (third included angle θ) is between 4 and 20 degrees. For example, the third sidewall inclination angle can be 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, or 20 degrees, or any value between any two of the foregoing angles. The range of the third sidewall inclination angle is not limited to this.

[0095] In some embodiments, when performing etching in the first etching stage, the third sidewall tilt angle can be controlled by adjusting the bias power based on the first pressure. Furthermore, the bias power is proportional to the third sidewall tilt angle.

[0096] The purpose of forming the sidewall notch 15 at the top of the first through-hole 13 is to provide a transitional foundation for the subsequent formation of the second through-hole 16, which has a smaller sidewall inclination angle. Specifically, the pre-formed sidewall notch 15 at the top of the first through-hole 13 with a certain inclination angle increases the opening width of the top of the first through-hole 13, forming an etching guide. This sidewall notch 15 then serves as a guide for subsequent etching, thereby further achieving an overall sidewall profile with a certain inclination angle.

[0097] Since the formed sidewall notch 15 has a relatively sharp chamfered step morphology, in order to prevent this step morphology from being transferred downward and affecting the smoothness of the sidewall, it is necessary to perform a rounding process on the top morphology of the first through-hole 13 at the sidewall notch 15. Furthermore, since the use of the first plasma etching process will form periodic scallop patterns 14 on the sidewall of the first through-hole 13, resulting in high sidewall roughness, this also requires a smoothing process to avoid affecting the smoothness of the sidewall when forming the second through-hole 16.

[0098] In some embodiments, by performing etching in the second etching stage of the second plasma etching process and using a second etching gas and a second pressure, the top morphology of the sidewall notch 15 of the first through hole 13 is smoothed, and the sidewall of the first through hole 13 is modified to make the sidewall of the first through hole 13 smooth.

[0099] refer to Figure 6 . In some embodiments, when performing the second etching stage of the second plasma etching process, the second etching gas used includes an oxidizing gas and a fluorocarbon gas. For example, the second etching gas includes O2 and CF4, and an inert gas, such as Ar, can be used as a dilution and dissociation gas. Similarly, in the absence of a mask, the first through hole 13 with the sidewall notch 15 formed is further etched to eliminate the sharper step morphology of the sidewall notch 15, so that the top morphology of the sidewall notch 15 of the first through hole 13 is smoothed. At the same time, the etching also has a modifying effect on the sidewall of the first through hole 13, which can eliminate the scallop pattern 14 on the sidewall, so that the original rough sidewall of the first through hole 13 is smoothed.

[0100] Compared with the first etching stage, when performing the second etching stage, CF4 is further added on the basis of O2, and the second pressure is increased to a certain extent to improve the isotropic etching ability of the reaction. At the same time, the side wall damage can be reduced by correspondingly reducing the bias power.

[0101] In some embodiments, during the second etching stage, the flow rate of O2 is 1 sccm to 200 sccm, and the flow rate of CF4 is 1 sccm to 150 sccm. For example, the flow rate of O2 can be 1 sccm, 2 sccm, 5 sccm, 10 sccm, 50 sccm, 100 sccm, 150 sccm, or 200 sccm, or any value between any two of the aforementioned flow rates of O2; the flow rate of CF4 can be 1 sccm, 2 sccm, 4 sccm, 8 sccm, 10 sccm, 20 sccm, 50 sccm, 100 sccm, or 150 sccm, or any value between any two of the aforementioned flow rates of CF4. The flow rate ranges of O2 and CF4 are not limited to these.

[0102] In some embodiments, the etching temperature during the second etching stage is 10° C. to 60° C. For example, the temperature can be 10° C., 11° C., 15° C., 20° C., 25° C., 30° C., 40° C., 45° C., 50° C., or 60° C., or any value between any two of the aforementioned temperature values. The temperature range is not limited to this.

[0103] In some embodiments, during the second etching phase, the second pressure is between 10 mtorr and 100 mtorr. For example, the second pressure can be 10 mtorr, 20 mtorr, 30 mtorr, 35 mtorr, 50 mtorr, 70 mtorr, 80 mtorr, or 100 mtorr, or any value between any two of the aforementioned pressure values. The second pressure range is not limited to this.

[0104] In some embodiments, during the second etching stage, the source power is between 100 W and 3000 W. For example, the source power can be 100 W, 200 W, 500 W, 800 W, 1000 W, 1500 W, 2000 W, 2500 W, or 3000 W, or any value between any two of the aforementioned source power values. The source power range is not limited to this.

[0105] In some embodiments, during the second etching stage, the bias power is 0 W to 90 W. For example, the bias power can be 0 W, 10 W, 20 W, 30 W, 40 W, 50 W, 60 W, 70 W, 80 W, or 90 W, or any value between any two of the aforementioned bias power values. The bias power range is not limited to this.

[0106] In some embodiments, the etching time during the second etching stage is 3 seconds to 12 seconds. For example, the etching time can be 3 seconds, 4 seconds, 5 seconds, 6 seconds, 7 seconds, 8 seconds, 9 seconds, 10 seconds, 11 seconds, or 12 seconds, or any value between any two of the aforementioned time values. The time range is not limited to this.

[0107] After the second etching stage, the surface of the sidewall notch 15 at the top of the first through-hole 13 is rounded, thereby rounding the entire top surface of the sidewall notch 15. Simultaneously, the second etching stage acts on the sidewall surface of the first through-hole 13, eliminating (or substantially eliminating) the original periodic scalloping 14 on the sidewall of the first through-hole 13, smoothing the sidewall of the first through-hole 13 and thereby reducing sidewall roughness and improving sidewall smoothness. After the second etching stage, the sidewall roughness of the first through-hole 13 can be reduced to approximately 9 nm to 22 nm, based on the first roughness. Furthermore, the top opening width of the first through-hole 13 is further expanded based on the width of the sidewall notch 15.

[0108] After the second etching stage, the first through hole 13 is formed with the top morphology of the sidewall notch 15 being rounded and the sidewall being smoothed, that is, the second transition through hole structure is formed. Figure 6 shown.

[0109] By performing etching in the second etching stage, the top morphology of the sidewall notch 15 is rounded, the sidewall of the first through hole 13 is smoothed, and the top opening width of the first through hole 13 is further expanded, thereby laying a good foundation for forming the second through hole 16 with a specific inclined sidewall morphology by performing etching in the second etching stage.

[0110] refer to Figure 7 In some embodiments, a third etching stage of the second plasma etching process is performed using a third etching gas and a third pressure to form a second through-hole 16 having a second opening width n and a second sidewall inclination angle. The second through-hole 16 has a sidewall profile that slopes inward and smoothly transitions from top to bottom. That is, the top opening width (second opening width n) of the second through-hole 16 is greater than the bottom width, and the aperture gradually decreases from top to bottom, forming a second through-hole 16 that is approximately trumpet-shaped, with a larger top and a smaller bottom.

[0111] In some embodiments, the second through hole 16 has an open shape with sidewalls convexly curved inwardly, such as Figure 7 shown.

[0112] In some embodiments, during the third etching stage of the second plasma etching process, the third etching gas used includes a sulfur-fluorine gas and a carbon-fluorine gas. For example, the third etching gas includes SF6 and C4F8, and an inert gas, such as Ar, can be used as a dilution and dissociation gas. Similarly, without a mask, the first through-hole 13 (second transition through-hole structure) is etched after the top morphology of the sidewall notch 15 is rounded and the sidewalls are smoothed, thereby further increasing the top opening width and forming a more inclined sidewall, that is, further reducing the sidewall inclination angle.

[0113] In some embodiments, when performing the third etching stage of the second plasma etching process, the third etching gas includes SF6, C4F8 and O2, wherein by adding an appropriate amount of O2, the polymer forming ability of C4F8 can be regulated to avoid excessive polymer production affecting the etching effect.

[0114] Compared to the second etching stage, during the third etching stage, the third pressure must be maintained at a higher level to widen the top opening and form a more inclined sidewall angle. This intensifies the isotropic etching during the reaction, resulting in an open, curved morphology. Furthermore, the use of the third etching gas can reduce the etching rate and avoid over-etching. Furthermore, the bottom width of the second through-hole 16 can be maintained by adjusting the bias power (relatively increasing the bias power can reduce the tendency for the bottom width to expand).

[0115] In some embodiments, during the third etching stage, the flow rate of SF6 is 1 sccm to 200 sccm, and the flow rate of C4F8 is 1 sccm to 200 sccm. For example, the flow rate of SF6 can be 1 sccm, 2 sccm, 5 sccm, 10 sccm, 50 sccm, 100 sccm, 150 sccm, or 200 sccm, or any value between any two of the aforementioned flow rates of SF6; the flow rate of C4F8 can be 1 sccm, 2 sccm, 5 sccm, 10 sccm, 50 sccm, 100 sccm, 150 sccm, or 200 sccm, or any value between any two of the aforementioned flow rates of C4F8. The flow rate ranges of SF6 and C4F8 are not limited to these.

[0116] In some embodiments, the etching temperature during the third etching stage is 10° C. to 60° C. For example, the temperature can be 10° C., 11° C., 15° C., 20° C., 25° C., 30° C., 40° C., 45° C., 50° C., or 60° C., or any value between any two of the aforementioned temperature values. The temperature range is not limited to this.

[0117] In some embodiments, during the third etching stage, the third pressure is between 110 mtorr and 200 mtorr. For example, the third pressure can be 110 mtorr, 120 mtorr, 130 mtorr, 135 mtorr, 150 mtorr, 170 mtorr, 180 mtorr, or 200 mtorr, or any value between any two of the foregoing pressure values. The third pressure range is not limited to this.

[0118] In some embodiments, during the third etching stage, the source power is between 100 W and 3000 W. For example, the source power can be 100 W, 200 W, 500 W, 800 W, 1000 W, 1500 W, 2000 W, 2500 W, or 3000 W, or any value between any two of the aforementioned source power values. The source power range is not limited to this.

[0119] In some embodiments, during the third etching stage, the bias power is 0 W to 100 W. For example, the bias power can be 0 W, 10 W, 20 W, 30 W, 40 W, 50 W, 60 W, 70 W, 80 W, 90 W, or 100 W, or any value between any two of the aforementioned bias power values. The bias power range is not limited to this.

[0120] In some embodiments, the etching time during the third etching stage is 5 seconds to 100 seconds. For example, the etching time can be 5 seconds, 10 seconds, 15 seconds, 20 seconds, 30 seconds, 40 seconds, 50 seconds, 65 seconds, 80 seconds, or 100 seconds, or any value between any two of the aforementioned time values. The time range is not limited to this.

[0121] In some embodiments, the inclination angle of the second sidewall is 80 degrees to 87 degrees, but is not limited thereto.

[0122] In some embodiments, the sidewalls of the second through-hole 16 have a second roughness. By performing the second etching stage, the top morphology of the sidewall notch 15 is rounded and the sidewalls of the first through-hole 13 are smoothed, thereby reducing the original sidewall roughness of the first through-hole 13. As a result, after performing the third etching stage, the second roughness of the sidewalls of the second through-hole 16 is also reduced accordingly, making the second roughness less than the original first roughness of the first through-hole 13.

[0123] After etching in the third etching stage, the second through hole 16 structure is formed, as shown in FIG. Figure 7 As shown. Figure 4 or Figure 3As can be seen, after the third etching stage, the top aperture width of the second via hole 16 (second aperture width n) is further enlarged. The second aperture width n of the final second via hole 16 is significantly larger than the first aperture width m of the first via hole 13. Moreover, the second via hole 16 has a more inclined sidewall, and the second sidewall inclination angle is also smaller than the first sidewall inclination angle of the first via hole 13 (second included angle β is smaller than the first included angle α). Moreover, the smooth morphology of the sidewall formed after the second etching stage is also continued in the third etching stage, so that the sidewall of the obtained second via hole 16 also has a smooth morphology, thereby improving the quality during subsequent metal filling and effectively preventing the generation of filling voids.

[0124] Step S16: Metal filling is performed on the second via hole to form a metal via hole.

[0125] Reference Figure 8 In some embodiments, a metal deposition process is used to fill the second via hole 16 with metal, fill the second via hole 16, and remove the excess metal material on the upper surface of the substrate 10 through a planarization process (such as a chemical mechanical polishing process) to form a metal via hole 17 with a flat top.

[0126] In the metal filling process, the improved etching structure of the second via hole 16 can better control the filling effect and avoid the defect of incomplete filling, so that the obtained metal via hole 17 can meet the requirements of high-performance devices in terms of electrical connection and heat dissipation, thereby improving the stability and performance of the device.

[0127] In some embodiments, the metal filled in the second via hole 16 includes copper or tungsten, but is not limited thereto.

[0128] Subsequent other process steps required for chip manufacturing can be continued, and will not be described again.

[0129] Figure 10 A traditional via hole A structure formed in a substrate by using a traditional periodic cyclic dry etching process is shown. The traditional via hole A is a vertical via hole, and the sidewall inclination angle is about 89 degrees (89°). Figure 10 Label 1 indicates that the top width in the X direction is 36.215 microns, label 2 indicates that the bottom width in the X direction is 30.758 microns, and label 3 indicates that the depth in the Y direction is 102.20 microns. Figure 11The figure shows the structure of a traditional through-hole B formed in a substrate using a traditional non-periodic cyclic dry etching process. This traditional through-hole B is an inclined through-hole with a sidewall inclination angle of approximately 87 degrees. The traditional periodic cyclic dry etching process has advantages in terms of etching rate and etching selectivity. The challenges it faces mainly focus on the control of the inclination angle, the smoothness of the top, and the roughness of the sidewalls, which limits its application in the manufacture of complex hole shapes and devices with higher requirements. Although the traditional non-periodic cyclic dry etching process can produce inclined through-holes with a certain slope, its low etching rate and poor selectivity make it impossible to produce hole walls with smaller inclination angles, thus limiting its application in high-performance devices.

[0130] Figure 9 The electron microscope diagram of the second through hole manufactured by the manufacturing method of the metal through hole of the present application is shown. The side wall of the second through hole has an inclination angle of about 85 degrees ( Figure 9 Mark 1 indicates a depth of 86.568 μm in the Y direction, mark 2 indicates a top width of 58.415 μm in the X direction, and mark 3 indicates a bottom width of 35.843 μm in the X direction). Figure 10 The traditional through-hole A and Figure 11 Compared with the traditional through hole B shown, Figure 9 The second through hole shown has a more inclined side wall, and the overall opening of the second through hole is larger, especially the top angle is more inclined and smoother, and the side wall is smooth, which is conducive to filling and forming a high-quality metal through hole.

[0131] The present application forms a through hole (second through hole 16) structure having a desired inclination angle (second sidewall inclination angle) by performing a first plasma etching process and a second plasma etching process in stages. The first plasma etching process can be used to achieve accurate through hole depth, thereby ensuring the stability and uniformity of the etching depth, while ensuring a reasonable balance between the etching rate and the selectivity, avoiding the problem of uneven depth and width, and providing a stable benchmark for subsequent processes. On this basis, the second plasma etching process is performed and further subdivided into three connected stages (the first etching process and the second plasma etching process). The first etching stage, the second etching stage and the third etching stage) can effectively improve the smoothness of the top of the through-hole, ensure that the hole mouth has no sharp corners, and repair the roughness of the side wall to achieve the ideal surface quality, and can produce a second through-hole 16 with a smaller inclination angle (inverted trapezoidal or trumpet-shaped through-hole), thereby improving the shortcomings of the traditional single etching process in making inclined through-holes (such as large hole wall roughness and top morphology defects), providing higher flexibility and precision, and thus meeting the requirements of the through-hole inclination angle in different applications, thereby meeting the needs of high-performance devices for electrical connection and heat dissipation.

[0132] An embodiment of the present application further provides a semiconductor structure, which includes a metal through-hole. The metal through-hole is obtained using the metal through-hole manufacturing method of the above embodiment.

[0133] refer to Figure 8 In some embodiments, the semiconductor structure includes a substrate 10, on which a second through hole 16 is provided. The second through hole 16 is filled with metal to form a metal through hole 17. Specifically, the metal through hole 17 is obtained using the metal through hole manufacturing method of the above embodiment.

[0134] In some embodiments, the semiconductor structure is applied to the field of three-dimensional advanced packaging, and metal vias formed on a substrate are used as vertical interconnect structures on a 3D integrated circuit chip.

[0135] In a third aspect, embodiments of the present application further provide a plasma processing apparatus, configured to perform the first and second plasma etching processes corresponding to the aforementioned embodiments to form the second through-holes corresponding to the aforementioned embodiments. The plasma processing apparatus may be, for example, an inductively coupled plasma (ICP) etching apparatus or a capacitively coupled plasma (CCP) etching apparatus.

[0136] In other aspects, embodiments of the present application further provide an electronic device comprising a semiconductor structure obtained using the method for manufacturing a metal via according to the above embodiment. The electronic device may be a storage device, a mobile phone, a computer, a tablet computer, a television, an artificial intelligence device, or the like.

[0137] In summary, the embodiments of the present application, by combining the first plasma etching process with the second plasma etching process, not only overcome the limitation of the traditional single etching process that cannot achieve high-precision control, but also provide a more refined and controllable metal through-hole etching solution for the manufacture of high-performance devices. In addition, the embodiments of the present application provide a complete set of efficient manufacturing processes for tapered through-holes with tilted angles, which solves challenges in depth, morphology, tilt angle, etc., so that during the metal filling process, the improved etching structure of the second through-hole 16 can better control the filling effect, avoid incomplete filling defects, and significantly improve the performance and reliability of the filled metal through-hole 17. The present application can be widely used in the manufacture of high-performance devices, including but not limited to integrated circuits, power electronic devices, image sensors (CIS), MEMS devices, and optoelectronic devices.

[0138] The above are only preferred embodiments of the present application, and the embodiments are not intended to limit the scope of protection of the present application. Therefore, any equivalent changes made using the description and drawings of the present application should also be included in the scope of protection of the present application.

Claims

1. A method for manufacturing a metal through hole, characterized in that: include: Performing a first plasma etching process with a mask to periodically etch a surface of one side of the substrate to form a first through hole in the substrate, wherein the first through hole has a first opening width and a first sidewall inclination angle; performing a maskless second plasma etching process to etch the sidewall of the first through hole to form the second through hole; the second plasma etching process comprises a first etching stage, a second etching stage, and a third etching stage connected in sequence, wherein the first etching stage uses a first etching gas and a first pressure to form a sidewall notch at the top of the first through hole, the second etching stage uses a second etching gas and a second pressure to round the top morphology of the sidewall notch and smooth the sidewall of the first through hole, and the third etching stage uses a third etching gas and a third pressure to form the second through hole having a second orifice width and a second sidewall inclination angle; the second orifice width is greater than the first orifice width, and the second sidewall inclination angle is less than the first sidewall inclination angle; the first etching gas, the second etching gas, and the third etching gas are different, and the first pressure, the second pressure, and the third pressure increase in sequence; The second through hole is filled with metal to form a metal through hole.

2. The method for manufacturing a metal through hole according to claim 1, wherein: The sidewall notch has a third sidewall inclination angle, and the third sidewall inclination angle is smaller than the second sidewall inclination angle.

3. The method for manufacturing a metal through hole according to claim 1, wherein: The sidewall of the first through hole has a first roughness, and the sidewall of the second through hole has a second roughness. When performing the second etching stage, the second roughness is made smaller than the first roughness by rounding the top morphology of the sidewall notch and smoothing the sidewall of the first through hole.

4. The method for manufacturing a metal through hole according to claim 1, wherein: The first etching gas includes an oxidizing gas; and / or the second etching gas includes an oxidizing gas and a carbon-fluorine gas; and / or the third etching gas includes a sulfur-fluorine gas and a carbon-fluorine gas.

5. The method for manufacturing a metal through hole according to claim 1, wherein: The first pressure is 8 mtorr to 50 mtorr; and / or the second pressure is 10 mtorr to 100 mtorr; and / or the third pressure is 110 mtorr to 200 mtorr.

6. The method for manufacturing a metal through hole according to claim 1, wherein: When executing the first etching stage, the bias power is 10W~100W, and the time is 3s~12s; and / or, when executing the second etching stage, the bias power is 0W~90W, and the time is 3s~12s; and / or, when executing the third etching stage, the bias power is 0W~100W, and the time is 5s~100s.

7. The method for manufacturing a metal through hole according to claim 1, wherein: The first etching gas includes O2, with a flow rate of 1 sccm to 200 sccm; and / or, the second etching gas includes O2 and CF4, the flow rate of O2 is 1 sccm to 200 sccm, and the flow rate of CF4 is 1 sccm to 150 sccm; and / or, the third etching gas includes SF6 and C4F8, the flow rate of SF6 is 1 sccm to 200 sccm, and the flow rate of C4F8 is 1 sccm to 200 sccm.

8. The method for manufacturing a metal through hole according to claim 2, wherein: The inclination angle of the first side wall is 88 degrees to 89 degrees; and / or the inclination angle of the second side wall is 80 degrees to 87 degrees; and / or the inclination angle of the third side wall is 4 degrees to 20 degrees.

9. The method for manufacturing a metal through hole according to claim 1, wherein: The substrate material includes silicon; and / or the metal filled in the second through hole includes copper or tungsten; and / or the first plasma etching process includes a periodic cycle of steps formed in sequence by a deposition step and an etching step, the process gas used in the deposition step includes C4F8, and the process gas used in the etching step includes SF6, and the first through hole is formed by alternately using C4F8 to deposit a passivation layer and using SF6 for etching; and / or the second through hole has a sidewall morphology that is inclined and curved inward from top to bottom.

10. A semiconductor structure, characterized in that Contains a metal through hole, and the metal through hole is obtained using the metal through hole manufacturing method according to any one of claims 1 to 9.

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