Electrochemical etching method and electrochemical etching device

Abstract

The present invention relates to the technical field of semiconductor processing, and provides an electrochemical etching method and an electrochemical etching device. The electrochemical etching method comprises: performing metallization treatment on the back surface, on which etching is not needed, of an object to be etched, and forming a metal layer on the back surface of said object; and performing electrochemical etching treatment on the front surface, on which etching is needed, of said object. Before the electrochemical etching treatment, metallization treatment is firstly performed on the back surface of said object, so that the resistance of said object can be greatly reduced, effectively avoiding the edge effect of said object; and the potentials at positions of the surface of said object can be accurately controlled by energizing the metal layer on the back surface of said object, so that the potentials at the positions of said object are kept consistent, and uneven current density distribution in the etching process is avoided, thereby accurately controlling the etching rate of said object, and greatly reducing the difficulty of electrochemical etching of said object having poor conductivity.

Description

Electrochemical etching method and electrochemical etching device Technical Field

[0001] The present invention relates to the field of semiconductor processing technology, and more particularly to an electrochemical etching method and an electrochemical etching device. Background Art

[0002] Electrochemical etching has great potential for application in semiconductor processing due to its ability to precisely control the etching rate. However, electrochemical etching requires the target to be highly conductive. Poor conductivity can lead to severe edge effects during etching. Specifically, the voltage difference between the central and edge regions of the target is too great, making it impossible to accurately control the potential across the surface. Consequently, electrochemical etching suffers from poor etching uniformity for targets with poor conductivity, hindering its widespread application in semiconductor processing.

[0003] Summary of the Invention

[0004] In order to solve the above problems existing in the prior art, the present invention provides an electrochemical etching method and an electrochemical etching device.

[0005] The present invention solves the above technical problems through the following technical solutions:

[0006] An electrochemical etching method, comprising:

[0007] Performing metallization treatment on the back side of the etching object that does not need to be etched, so as to form a metal layer on the back side of the etching object;

[0008] The front surface of the etching object to be etched is subjected to electrochemical etching treatment.

[0009] Preferably, before metallizing the back side of the etching object which does not need to be etched, a barrier layer is deposited on the back side of the etching object.

[0010] Preferably, before depositing a barrier layer on the back side of the etching object, the back side of the etching object is further cleaned.

[0011] Preferably, after the front surface of the etching object to be etched is subjected to electrochemical etching, the method further comprises:

[0012] removing the metal layer on the back side of the etching object;

[0013] The barrier layer on the back side of the etched object is removed.

[0014] Preferably, after the electrochemical etching is performed on the front side of the etching object to be etched, the method further includes removing the metal layer on the back side of the etching object.

[0015] Preferably, the thickness of the metal layer is greater than or equal to 10 nm.

[0016] Preferably, the material of the barrier layer is any one of tantalum oxide, tantalum nitride, tantalum, titanium, titanium nitride, and cobalt.

[0017] Preferably, the thickness of the barrier layer is less than or equal to 1 nm.

[0018] Preferably, in the step of performing electrochemical etching on the front surface of the etching object to be etched, power is supplied to the metal layer in a surface contact manner.

[0019] Preferably, in the step of performing electrochemical etching on the front surface of the etching object to be etched, the etching solution used in the electrochemical etching is any one of KOH, HF and TMAH.

[0020] Preferably, in the step of performing electrochemical etching on the front surface of the etching object to be etched, the etching object is placed on a chuck of an electrochemical etching device by edge clamping.

[0021] An electrochemical etching device, comprising:

[0022] a coating module, configured to perform metallization treatment on the back side of the etching object to form a metal layer on the back side of the etching object;

[0023] An electrochemical etching module, configured to perform electrochemical etching on the front surface of the etching object;

[0024] Control module, including:

[0025] A transmission mechanism, used for transmitting the etching object to the coating module, and transferring the etching object from the coating module to the electrochemical etching module;

[0026] A controller, configured to send operating instructions to the transmission mechanism, the plating module, and the electrochemical etching module;

[0027] The controller controls the transmission mechanism to first transfer the etching object to the coating module. When the etching object reaches the coating module, the controller sends a working instruction to the coating module, and the coating module performs metallization on the back of the etching object.

[0028] After the coating module finishes working, the controller controls the transmission mechanism to transfer the etching object from the coating module to the electrochemical etching module;

[0029] When the etching object reaches the electrochemical etching module, the controller sends a working instruction to the electrochemical etching module to control the electrochemical etching module to perform electrochemical etching on the front surface of the etching object.

[0030] The positive progressive effect of the present invention is that: in the present invention, before the electrochemical etching treatment, the back side of the etching object is first metallized, which can greatly reduce the resistance of the etching object, thereby effectively avoiding the edge effect of the etching object; during the electrochemical treatment, by applying power to the metal layer on the back side of the etching object, the electric potential at various locations on the surface of the etching object can be accurately controlled, so that the electric potential at various locations on the etching object remains consistent, avoiding uneven current density distribution during the etching process, and then accurately controlling the etching rate of the etching object, greatly reducing the difficulty of electrochemical etching of etching objects with poor conductivity.

[0031] Summary of the Figures

[0032] The features and properties of the present invention are further described by the following examples and accompanying drawings.

[0033] FIG1 is a schematic flow diagram of an electrochemical etching method according to Example 1 of the present invention;

[0034] FIG2 is a schematic flow chart of the electrochemical etching method according to Example 2 of the present invention.

[0035] Preferred embodiments of the present invention

[0036] To illustrate the technical content, structural features, achieved objectives and effects of the present invention in detail, embodiments will be described below in conjunction with drawings, but the present invention is not limited to the scope of the embodiments.

[0037] Example 1

[0038] Electrochemical etching processes can precisely control the etching rate by selecting an appropriate electrolyte and controlling the potential and current of the working electrode. Therefore, electrochemical etching holds great potential in semiconductor processing. Electrochemical etching typically targets materials with good electrical conductivity, which results in consistent electrical potential across different locations and uniform etching. However, for materials with poor electrical conductivity, regions with high electrical resistance can easily develop high local potentials during the etching process, leading to uneven etching. Furthermore, poor electrical conductivity can reduce the etching rate and prolong the etching time. For example, silicon has very poor electrical conductivity; even when cut into small 2cm*2cm pieces, its resistance can reach as high as 1MΩ. While increasing the voltage during electrochemical etching of materials with poor electrical conductivity is often used to increase the etching rate, this still fails to achieve uniform etching. Currently, there is no optimal method for electrochemical etching of materials with poor electrical conductivity.

[0039] The present invention provides an electrochemical etching method that can be applied to materials with poor conductivity. The etching object in the present invention is a silicon wafer, but the etching object is not limited to this and can also be other materials with poor conductivity.

[0040] The electrochemical etching method is shown in FIG1 and includes the following steps:

[0041] S100 , performing metallization treatment on the back side of the silicon wafer that does not need to be etched, to form a metal layer on the back side of the silicon wafer.

[0042] S200: Performing electrochemical etching on the front side of the silicon wafer that needs to be etched.

[0043] Before the electrochemical etching process, the back of the silicon wafer is first metallized, which can greatly reduce the resistance of the silicon wafer, thereby effectively avoiding the edge effect of the silicon wafer. During the electrochemical treatment, by applying power to the metal layer on the back of the silicon wafer, the electric potential at various locations on the silicon wafer surface can be accurately controlled, so that the electric potential at various locations on the silicon wafer remains consistent, avoiding uneven current density distribution during the etching process, and thus maintaining a consistent electrochemical etching rate on the front of the silicon wafer. Therefore, this embodiment greatly reduces the difficulty of etching silicon wafers using electrochemical methods, optimizes the performance and effect of the electrochemical silicon etching process, and enables the process of etching silicon wafers using electrochemical methods to be mass-produced.

[0044] In this embodiment, metals with good electrical conductivity, such as copper, silver, aluminum, etc., are selected.

[0045] The thickness of the metal layer is greater than or equal to 10nm. A thicker metal layer can provide lower resistance, enhance the electrical conductivity of the etched object, maintain a consistent electrical potential across the object after power is applied, and is less susceptible to damage during power application, which helps improve stability during the electrochemical etching process. Furthermore, a thicker metal layer can provide better structural support and stability to a certain extent, increasing the mechanical strength of the back of the etched object and reducing the risk of deformation or cracking.

[0046] In step S200, power is supplied to the metal layer by surface contact, which is less likely to damage the metal layer than point contact and provides more stable power supply.

[0047] In step S200 , the etching solution used in electrochemical etching is any one of KOH, HF and TMAH.

[0048] In step S200, the object to be etched is placed on the chuck of the electrochemical etching apparatus by edge clamping. This edge clamping can avoid damaging the metal layer on the back of the object to be etched, thereby affecting the difference in resistance on the back of the object to be etched, and ultimately affecting the uniformity of the electrochemical etching.

[0049] In this embodiment, a metallization process is performed on a silicon wafer by deposition, and a metal layer is grown on the surface of the silicon wafer. Since metal may intrude into the silicon wafer during the metallization process, affecting the subsequent production process, a step S90 is included before step S100 to deposit a barrier layer on the back side of the silicon wafer. The deposition of the barrier layer can effectively control the diffusion of the metal and prevent the metal from entering the interior of the silicon wafer. In addition, the deposition of the barrier layer can also provide good metal adhesion. The barrier layer can increase the adhesion of the metal to the back side of the silicon wafer, ensuring good contact between the metallization layer and the back side of the silicon wafer.

[0050] The material of the barrier layer may be any one of tantalum oxide, tantalum nitride, tantalum, titanium, titanium nitride, and cobalt.

[0051] In addition, the thickness of the barrier layer needs to be less than or equal to 1nm. The thin thickness of the barrier layer can prevent the metal layer from diffusing into the interior of the etched object, while also ensuring the consistency of the potential at all locations of the etched object after power is applied.

[0052] In addition, before step S90, step S80 is also included to clean the back side of the silicon wafer, which is helpful to remove impurities on the back side of the silicon wafer and enhance the bonding between the barrier layer and the silicon wafer.

[0053] Finally, after S200 also includes:

[0054] S300, removing the metal layer on the back side of the silicon wafer.

[0055] S400, removing the barrier layer on the back side of the silicon wafer.

[0056] Of course, if the metal layer needs to be retained after etching is completed, S300 and S400 may not be performed.

[0057] Example 2

[0058] In this embodiment of the invention, if the metal is not likely to penetrate into the interior of the etched object during the metallization treatment on the back side of the etched object, then S90 is not required. As shown in FIG2 , the electrochemical etching method at this time includes:

[0059] S100, performing metallization treatment on the back side of the silicon wafer that does not need to be etched, to form a metal layer on the back side of the silicon wafer;

[0060] S200, performing electrochemical etching on the front side of the silicon wafer that needs to be etched;

[0061] S300: Clear the metal layer on the back side of the silicon wafer.

[0062] In this embodiment, aluminum may be selected as the metal layer for deposition, wherein the aluminum is doped with 1%-2% silicon.

[0063] In other embodiments, the method of metallizing the back side of the silicon wafer is not limited thereto. A metal sheet with a relatively high surface flatness may be prepared and directly bonded to the back side of the silicon wafer.

[0064] Of course, if the metal layer needs to be retained after etching is completed, S300 may not be performed.

[0065] Of course, in this embodiment, the back side of the silicon wafer may also be cleaned before S100 , thereby increasing the bonding ability between the metal layer and the silicon wafer.

[0066] Example 3

[0067] An embodiment of the present invention provides an electrochemical etching device, which includes a coating module, an electrochemical etching module and a control module. The coating module is used to perform metallization treatment on the back of the etching object to form a metal layer on the back of the etching object, and the electrochemical etching module is used to perform electrochemical etching treatment on the front of the etching object.

[0068] The control module includes: a transmission mechanism for transmitting the etching object to the plating module and transferring the etching object from the plating module to the electrochemical etching module; a controller for sending work instructions to the transmission mechanism, the plating module and the electrochemical etching module; the controller controls the transmission mechanism to first transmit the etching object to the plating module, and when the etching object reaches the plating module, the controller sends a work instruction to the plating module, and the plating module performs metallization treatment on the back of the etching object; after the plating module finishes work, the controller controls the transmission mechanism to transfer the etching object from the plating module to the electrochemical etching module; when the etching object reaches the electrochemical etching module, the controller sends a work instruction to the electrochemical module, and controls the electrochemical etching module to perform electrochemical etching treatment on the front of the etching object.

[0069] The coating module can use an existing electroplating device to metallize the back of the etched object by electroplating. The electrochemical etching module can use an existing electrochemical etching machine. The transmission mechanism can use an existing transmission system, such as a robot.

[0070] Before the electrochemical etching module etches the front side of the etching object, the back side of the etching object is first metallized by the coating module to reduce the resistance of the back side of the etching object, so as to accurately control the electric potential at various locations on the surface of the etching object, keep the electric potential at various locations consistent, avoid uneven current density distribution during the etching process, and thus keep the electrochemical etching rate at the front side of the etching object consistent.

[0071] Although the above describes specific embodiments of the present invention, it should be understood by those skilled in the art that these are merely illustrative and that various changes or modifications may be made to these embodiments without departing from the principles and essence of the present invention. Therefore, the scope of protection of the present invention is defined by the appended claims.

Claims

1. An electrochemical etching method, characterized in that: include: Performing metallization treatment on the back side of the etching object that does not need to be etched, so as to form a metal layer on the back side of the etching object; The front side of the etching object to be etched is subjected to electrochemical etching treatment.

2. The electrochemical etching method according to claim 1, characterized in that: Before metallizing the back side of the etching object which does not need to be etched, a barrier layer is deposited on the back side of the etching object.

3. The electrochemical etching method according to claim 2, characterized in that: Before depositing a barrier layer on the back side of the etching object, the back side of the etching object is cleaned.

4. The electrochemical etching method according to claim 2, characterized in that: After the front side of the etching object to be etched is subjected to electrochemical etching, the method further comprises: removing the metal layer on the back side of the etching object; The barrier layer on the back side of the etching object is removed.

5. The electrochemical etching method according to claim 1, characterized in that: After the front side of the etching object to be etched is subjected to electrochemical etching, the method further includes removing the metal layer on the back side of the etching object.

6. The electrochemical etching method according to claim 1, characterized in that: The thickness of the metal layer is greater than or equal to 10 nm.

7. The electrochemical etching method according to claim 2, characterized in that: The material of the barrier layer is any one of tantalum oxide, tantalum nitride, tantalum, titanium, titanium nitride and cobalt.

8. The electrochemical etching method according to claim 2, characterized in that: The thickness of the barrier layer is less than or equal to 1 nm.

9. The electrochemical etching method according to claim 1, characterized in that: In the step of performing electrochemical etching on the front side of the etching object to be etched, power is supplied to the metal layer in a surface contact manner.

10. The electrochemical etching method according to claim 1, characterized in that: In the step of electrochemically etching the front side of the etching object to be etched, the etching solution used in the electrochemical etching is any one of KOH, HF and TMAH.

11. The electrochemical etching method according to claim 1, characterized in that: In the step of electrochemically etching the front side of the etching object to be etched, the etching object is placed on a chuck of an electrochemical etching device by edge clamping.

12. An electrochemical etching device, characterized in that: The device comprises: A coating module, used for performing metallization treatment on the back side of the etching object to form a metal layer on the back side of the etching object; An electrochemical etching module, used for performing electrochemical etching on the front side of the etching object; Control module, including: A transmission mechanism, used for transmitting the etching object to the coating module, and transferring the etching object from the coating module to the electrochemical etching module; A controller, used for sending working instructions to the transmission mechanism, the plating module and the electrochemical etching module; The controller controls the transmission mechanism to first transfer the etching object to the coating module. When the etching object reaches the coating module, the controller sends a working instruction to the coating module, and the coating module performs metallization on the back of the etching object. After the coating module finishes working, the controller controls the transmission mechanism to transfer the etching object from the coating module to the electrochemical etching module; When the etching object reaches the electrochemical etching module, the controller sends a working instruction to the electrochemical etching module to control the electrochemical etching module to perform electrochemical etching on the front side of the etching object.

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