Electrostatic chuck with automatic release of residual charge

Abstract

The application discloses a residual charge automatic release electrostatic chuck and belongs to the technical field of semiconductor plasma equipment. The electrostatic chuck mainly comprises an upper insulating ceramic layer, an electrode layer, a conductive ceramic layer and a lower insulating ceramic layer. The conductive ceramic layer is arranged between the upper insulating ceramic layer and the lower insulating ceramic layer, and a plurality of conductive ceramic columns of the conductive ceramic layer penetrate through the upper insulating ceramic layer and the lower insulating ceramic layer. Therefore, when a wafer is placed on the electrostatic chuck, the bottom surface of the wafer is in contact with the upper conductive ceramic column, and the lower conductive ceramic column is coupled to a grounding electrode. After a process is completed, the structure can provide a path for releasing residual charge of the wafer. Since the conductive ceramic layer, the upper insulating ceramic layer, the electrode layer and the lower insulating ceramic layer are integrally laminated and formed, and the same ceramic material is combined therebetween, the electrostatic chuck has the advantages of good matching degree, good combination stability and the like.

Description

Technical Field

[0001] This invention relates to the field of semiconductor equipment technology, and in particular to an electrostatic chuck for automatic release of residual charge. Background Technology

[0002] Electrostatic chucks (also simply called "chucks") are used for handling semiconductor wafers and microelectronic devices. A chuck securely holds a workpiece, such as a semiconductor wafer or microelectronic device substrate, in place to perform processes on the workpiece's surface. The upper surface of the chuck, sometimes referred to as the "substrate support surface," may include specialized features to improve chuck performance.

[0003] After the plasma etching process is completed, the electrostatic chuck stops outputting the electrostatic force used to hold the wafer, providing the necessary conditions for the subsequent wafer removal process. However, during the etching process, the ionization reaction generates a large amount of charge, which tends to accumulate at the interface between the wafer and the electrostatic chuck. Even after the electrostatic force output stops, this residual charge can still cause the wafer to remain strongly attracted to the electrostatic chuck, preventing normal wafer removal or causing problems such as breakage, scratches, or wafer misalignment during removal due to the residual charge's attraction. This directly impacts production efficiency and costs. Furthermore, most semiconductor equipment currently requires an additional destatic discharge step (such as Ar plasma) after the etching process to remove the residual charge from the electrostatic chuck. This destatic discharge step takes a certain amount of time (10-20 seconds), thus increasing the total etching process time per wafer.

[0004] Therefore, there is an urgent need to design an electrostatic chuck that automatically releases residual charge. This can effectively solve the various problems caused by the wafers still being attracted by residual charge after the process is completed, thereby improving production efficiency and product yield, and effectively reducing production costs. Summary of the Invention

[0005] The purpose of this invention is to provide an electrostatic chuck with automatic residual charge release to solve the problems mentioned in the background art.

[0006] To achieve the above objectives, the present invention provides the following technical solution: an electrostatic chuck for automatic release of residual charge, comprising: An upper ceramic insulating layer is provided, which is in direct contact with the wafer. An electrode layer is disposed below the upper ceramic insulating layer; A conductive ceramic layer is disposed below the electrode layer; A lower ceramic insulating layer is disposed below the conductive ceramic layer; The conductive ceramic layer extends upward with multiple upper conductive ceramic pillars, which pass through the electrode layer and the upper ceramic insulating layer in sequence and make direct contact with the wafer. The conductive ceramic layer extends downward with multiple lower conductive ceramic pillars, which pass through the lower ceramic insulating layer and are connected to the ground electrode.

[0007] Furthermore, the upper ceramic insulating layer extends upward with multiple bumps, the tips of which are in direct contact with the wafer.

[0008] Furthermore, the outer edge of the upper ceramic insulating layer protrudes upward to form a sealing ring.

[0009] Furthermore, the electrode layer includes an electrode and an electrically insulating plate, with the electrode disposed inside the electrically insulating plate.

[0010] Furthermore, a metal base is provided below the lower ceramic insulating layer, and the lower conductive ceramic pillar is in direct contact with the upper surface of the metal base and connected to the grounding electrode through the metal base.

[0011] Furthermore, the metal base is also provided with at least three lifting pins and helium gas channels. The lifting pins and helium gas channels pass through the metal base, the lower ceramic insulating layer, the conductive ceramic layer and the upper ceramic insulating layer from bottom to top, and are connected to the helium gas channels formed by the gaps between the multiple protrusions.

[0012] Furthermore, the metal base is also provided with horizontally arranged cooling water channels.

[0013] Furthermore, the height of each of the protrusions is the same as the top of the sealing ring.

[0014] Furthermore, the resistivity of the conductive ceramic layer is 10⁻⁶. 9 ~10 11 Ω·cm.

[0015] The present invention has at least the following beneficial effects: 1. The residual charge self-release path of the present invention can effectively release residual charge, that is, eliminate the adsorption force of residual charge on wafer after the process, thereby reducing or completely solving the problems such as breakage, scratches, and displacement caused by the adsorption force of residual charge on wafer when the wafer is lifted, ensuring that the wafer can be smoothly and intactly removed by the robotic arm, thereby effectively reducing the number of maintenance and improving product yield.

[0016] 2. The residual charge self-release path of the present invention can effectively shorten the wafer desorption time after the process is completed, thereby effectively improving the overall production efficiency of the equipment and reducing production costs.

[0017] 3. The residual charge self-release path of this invention can effectively reduce the problem of particulate matter adsorbed on the surface of the electrostatic chuck due to residual electrostatic charge not being able to be removed. This effectively changes the internal environment of the chamber, improving wafer yield.

[0018] 4. The present invention uses conductive ceramic material, which has easier conductivity and manufacturing process and is less likely to cause grounding failure due to high temperature firing during the production of electrostatic chuck. It can also reduce wear and contamination between conductive ceramic and wafer. Attached Figure Description

[0019] Figure 1 Cross-sectional view of Embodiment 1 of the present invention; Figure 2 Exploded cross-sectional view of Embodiment 1 of the present invention; Figure 3 Cross-sectional view of Embodiment 2 of the present invention; Figure 4 Exploded cross-sectional view of Embodiment 2 of the present invention; Figure 5 Top view of the structure after removing the wafer in Embodiment 2 of the present invention; The labels in the attached diagram are as follows: 10, wafer; 20, upper ceramic insulating layer; 211, sealing ring; 212, bump; 213, helium channel; 30, electrode layer; 311, electrode pattern; 312, electrical insulating plate; 40, conductive ceramic layer; 411, upper conductive ceramic pillar; 412, lower conductive ceramic pillar; 50, lower ceramic insulating layer; 60, metal base; 611, cooling water channel; 612, lifting pin and helium channel; 613, upper surface of metal base. Detailed Implementation

[0020] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0021] As an embodiment of the present invention, please refer to Figures 1-2 An electrostatic chuck with automatic residual charge release, comprising: An upper ceramic insulating layer 20 is in direct contact with the wafer 10. Electrode layer 30 is disposed below the upper ceramic insulating layer 20; A conductive ceramic layer 40 is disposed below the electrode layer 30; The lower ceramic insulating layer 50 is disposed below the conductive ceramic layer 40; The conductive ceramic layer 40 extends upward with multiple upper conductive ceramic pillars 411, which pass through the electrode layer 30 and the upper ceramic insulating layer 20 in sequence and directly contact the wafer 10. The conductive ceramic layer 40 extends downward with multiple lower conductive ceramic pillars 412, which pass through the lower ceramic insulating layer 50 and connect to the ground electrode. The upper ceramic insulating layer 20 extends upward with multiple protrusions 212, the tips of which directly contact the wafer 10. The outer edge of the upper ceramic insulating layer 20 protrudes upward to form a sealing protrusion ring 211. The electrode layer 30 includes an electrode 311 and an electrical insulating plate 312, with the electrode 311 disposed inside the electrical insulating plate 312.

[0022] The electrostatic chuck electrode layer 30 is electrically insulated from the conductive ceramic layer 40. The conductive ceramic layer 40 is integrally stacked with the electrode layer 30. The upper insulating ceramic layer 20 is integrally stacked with the electrode layer 30, and the conductive ceramic layer 40 is integrally stacked with the lower insulating ceramic layer 50.

[0023] In practical use, the wafer 10 is placed on the electrostatic chuck by a robotic arm. A DC voltage is applied to the electrode 311 by the electrostatic chuck power supply or an external power source, generating electrostatic force to attract and flatten the wafer 10 onto the electrostatic chuck. The electrostatic chuck comprises, from top to bottom, an upper insulating ceramic layer 20, an electrode layer 30, a conductive ceramic layer 40, and a lower insulating ceramic layer 50. The electrode layer 30 is electrically insulated from the conductive ceramic layer 40, the upper insulating ceramic layer 20, and the lower insulating ceramic layer 50. The conductive ceramic layer 40 extends upwards from the upper insulating ceramic layer 20, extending multiple upper conductive ceramic pillars 411 that pass through the electrode layer 30 and the upper insulating ceramic layer 20 in sequence. The conductive ceramic layer 40 extends downwards from the lower insulating ceramic layer 50... A lower conductive ceramic pillar 412 passes through the lower insulating ceramic layer 50 and is coupled to the ground electrode; the upper insulating ceramic layer 20 extends upward with multiple protrusions 212, the upper surface of which is flush with the upper conductive ceramic pillar 411, and a sealing protrusion 211 extends from the edge of the upper surface of the upper insulating ceramic layer 20. The sealing protrusion 211 is flush with the upper surface of the protrusions 212 and the upper conductive ceramic pillar 411, which can ensure the sealing of the helium channel 213 when the wafer 10 is placed on the electrostatic chuck.

[0024] During the process, the conductive ceramic pillar 412 can still be grounded. The reason for this is that the conductive ceramic layer 40 selected in the design has a medium-to-high resistivity, with a resistivity range of 10. 9 ~10 11Ω·cm, such as high-purity conductive ceramics doped with a very small amount of zirconium oxide, has a conductivity between that of a conductor and an insulator, and is therefore called a weakly conductive ceramic. When a continuous high voltage is applied to the electrostatic chuck, the wafer 10 and the electrostatic chuck will generate charge polarization at a rate in milliseconds with an electric field transfer efficiency of 85%~95%. Although there are a few upper conductive ceramic pillars 411 on the back of the wafer 10 that are in close contact with it, their number accounts for only 1%~2% of the total area of ​​the wafer 10, so the contact area with the wafer 10 is very limited. In addition, its conductivity is between that of a conductor and an insulator, belonging to weakly conductive ceramics. Therefore, compared with the rate of charge polarization, the amount of charge it can conduct away is very small, so its impact on the electrostatic adsorption force is extremely small.

[0025] However, once the process is complete and the voltage applied to the electrostatic chuck is stopped, there will be no more charge polarization between the electrostatic chuck and wafer 10. Furthermore, the grounding of the conductive ceramic will quickly conduct away any remaining polarized charge. This fundamentally eliminates the residual electrostatic force's attraction to the wafer, ensuring a safe and controllable wafer 10 removal process.

[0026] As described above, the electrostatic chuck of the present invention with automatic residual charge release mainly consists of a conductive ceramic layer disposed between the upper and lower insulating ceramic layers, with multiple upper and lower conductive ceramic pillars passing through the upper and lower insulating ceramic layers. Thus, when the wafer is adsorbed onto the electrostatic chuck, the bottom surface of the wafer contacts multiple upper conductive ceramic pillars, and the lower conductive ceramic pillars are coupled to the grounding electrode. This structure establishes a path for automatic release of residual charge from the wafer. Because the conductive ceramic layer is stacked with at least one of the upper and lower insulating ceramic layers, and they are all ceramic materials combined without the combination of dissimilar materials, the electrostatic chuck has advantages such as high bonding stability and simple manufacturing.

[0027] As a second embodiment of the present invention, please refer to Figures 3-5 An electrostatic chuck with automatic residual charge release, comprising: An upper ceramic insulating layer 20 is in direct contact with the wafer 10. Electrode layer 30 is disposed below the upper ceramic insulating layer 20; A conductive ceramic layer 40 is disposed below the electrode layer 30; The lower ceramic insulating layer 50 is disposed below the conductive ceramic layer 40; The conductive ceramic layer 40 extends upward with multiple upper conductive ceramic pillars 411, which pass through the electrode layer 30 and the upper ceramic insulating layer 20 in sequence and directly contact the wafer 10. The conductive ceramic layer 40 extends downward with multiple lower conductive ceramic pillars 412, which pass through the lower ceramic insulating layer 50 and are connected to the grounding electrode.

[0028] The upper ceramic insulating layer 20 extends upward with multiple protrusions 212, the tips of which directly contact the wafer 10. The outer edge of the upper ceramic insulating layer 20 protrudes upward to form a sealing ring 211. The electrode layer 30 includes electrodes 311 and an electrical insulating plate 312, with the electrodes 311 disposed inside the electrical insulating plate 312. A metal base 60 is also provided below the lower ceramic insulating layer 50. The lower conductive ceramic pillar 412 directly contacts the upper end face 613 of the metal base 60 and is connected to the grounding electrode through the metal base 60. The metal base 60 also has at least two lifting pins and a helium gas channel 612, which sequentially penetrate the metal base 60, the lower ceramic insulating layer 50, the conductive ceramic layer 40, and the upper ceramic insulating layer 20 from bottom to top, and are connected to the helium gas channel 213 formed by the gaps between the multiple protrusions 212. A cooling water channel 611 is also horizontally arranged inside the metal base 60. The resistivity of the conductive ceramic layer 40 is 10 Ω·cm. 9 ~10 11 Ω·cm.

[0029] In practical use, after the wafer 10 is placed in the electrostatic chuck, the electrostatic chuck power supply or an external power supply applies a DC voltage to the electrode 311, generating an electrostatic field. Due to this electrostatic field, the internal charge of the wafer 10 placed on the electrostatic chuck is polarized or forms an electric dipole, thereby generating a Johnson-Labec force. The wafer 10 is firmly fixed on the electrostatic chuck, specifically at the top of the upper insulating ceramic layer 20. In addition, the electrostatic chuck is also designed with helium gas channels 213 and cooling water channels 611. The helium gas channels refer to the gaps between the bumps 212. Their function is to allow helium gas to flow freely and comprehensively on the back of the wafer, making the temperature of the entire wafer more uniform. At the same time, it also effectively conducts heat to the upper insulating ceramic 20, conductive ceramic 40, lower insulating ceramic 50, and finally to the metal base 60. Finally, the heat is carried away by the cooling water. If a high-temperature heating process is required, the heat can also be transferred to the wafer in the reverse direction to meet the process requirements. After the process is completed and the electrostatic chuck power supply is cut off, the electric dipoles formed inside wafer 10 due to the electric field will be conducted through the upper conductive ceramic pillar 411 to the conductive ceramic 40, and then through the lower conductive ceramic pillar 412 to the metal base 60. The metal base is connected to the chamber, and the residual charge is finally conducted away through the metal base. Then, the wafer is lifted upward by the lifting pin and the helium gas channel 612. One of the lifting pins and the helium gas channel 612 can serve as the helium filling inlet, and then the wafer is removed by the robotic arm. The upper surfaces of the sealing ring 211 and the bump 212, as well as the upper surface of the upper conductive ceramic pillar 411, are flush to reduce the loss of helium gas on the back of the wafer. When the upper end face 613 of the metal base and the lower end face 613 of the lower insulating ceramic layer are joined, a special thermally conductive and bonding aid material is added to increase the bonding stability between the ceramic and the metal, as well as the high reliability of thermal conductivity.

[0030] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0031] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. An electrostatic chuck with automatic residual charge release, characterized in that, include: An upper ceramic insulating layer (20) is in direct contact with the wafer (10); An electrode layer (30) is disposed below the upper ceramic insulating layer (20); A conductive ceramic layer (40) is disposed below the electrode layer (30); A lower ceramic insulating layer (50) is disposed below the conductive ceramic layer (40); The conductive ceramic layer (40) extends upward with multiple upper conductive ceramic pillars (411), which pass through the electrode layer (30) and the upper ceramic insulating layer (20) in sequence and directly contact the wafer (10). The conductive ceramic layer (40) extends downward with multiple lower conductive ceramic pillars (412), which pass through the lower ceramic insulating layer (50) and are connected to the ground electrode.

2. The electrostatic chuck for automatic release of residual charge according to claim 1, characterized in that: The upper ceramic insulating layer (20) extends upward with a plurality of bumps (212), the top of which is in direct contact with the wafer (10).

3. The electrostatic chuck for automatic release of residual charge according to claim 2, characterized in that: The outer edge of the upper ceramic insulating layer (20) protrudes upward to form a sealing ring (211).

4. The electrostatic chuck for automatic release of residual charge according to claim 1, characterized in that: The electrode layer (30) includes an electrode (311) and an electrical insulating plate (312), wherein the electrode (311) is disposed inside the electrical insulating plate (312).

5. An electrostatic chuck for automatic release of residual charge according to claim 1, characterized in that: A metal base (60) is provided below the lower ceramic insulating layer (50). The lower conductive ceramic pillar (412) is in direct contact with the upper end face (613) of the metal base (60) and is connected to the grounding electrode through the metal base (60).

6. The electrostatic chuck for automatic release of residual charge according to claim 5, characterized in that: The metal base (60) is also provided with at least three lifting pins and helium channels (612). The lifting pins and helium channels (612) pass through the metal base (60), the lower ceramic insulating layer (50), the conductive ceramic layer (40) and the upper ceramic insulating layer (20) from bottom to top, and are connected to the helium channels (213) formed by the gaps between the multiple protrusions (212).

7. An electrostatic chuck for automatic release of residual charge according to claim 6, characterized in that: The metal base (60) is also provided with a horizontal cooling water channel (611).

8. An electrostatic chuck for automatic release of residual charge according to claim 3, characterized in that: The height of the plurality of protrusions (212) is the same as the top of the sealing protrusion (211).

9. An electrostatic chuck for automatic release of residual charge according to claim 1, characterized in that: The resistivity of the conductive ceramic layer (40) is 10. 9 ~10 11 Ω·cm.

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