Plasma etching electrode

Abstract

The utility model relates to a plasma etching electrode. The etching electrode is provided with a circular section perpendicular to a central shaft. An inner surface of the etching electrode is formed on one side facing the plasma chamber along the central axis direction, and an outer surface of the etching electrode is formed on one side outside the plasma chamber along the central axis direction; air holes penetrating through the outer surface and the inner surface are distributed in the surface of the etching electrode, and the diameter of the air holes ranges from 0.35 mm to 0.5 mm. The air holes annularly expand towards the edge on the etching electrode by taking the central shaft as the center, and the distance between the rings is firstly increased and then reduced from the central shaft to the edge along the radial direction. According to the etching electrode, stable conveying of gas in a single gas hole is ensured through the size design of the gas holes distributed in the etching electrode, so that the stability and the consistency of the gas sent out from the gas holes are ensured, and the etching uniformity is improved. In addition, the design of the sizes of the air holes also gives consideration to the production efficiency of the etching electrode.

Description

Technical Field

[0001] This utility model relates to the field of plasma etching equipment technology, and specifically to a plasma etching electrode. Background Technology

[0002] Etching is used to precisely remove patterns or features from the surface of a material. The mainstream etching method is dry etching, which uses low-temperature plasma to etch the material surface. Dry etching is widely used in semiconductor manufacturing and requires specific open-hole electrodes. The holes on the electrodes form plasma channels. After a potential difference is established between the electrodes, the plasma bombards the workpiece at a certain velocity.

[0003] Due to the large wafer size, current processes typically produce wafers larger than 250mm, with advanced processes reaching diameters of up to 450mm. As the wafer etching area increases, edge effects and other factors have a more pronounced impact on plasma beam stability, making it more difficult to ensure uniformity in dry etching. Utility Model Content

[0004] Given that the consistency of the plasma beam in large-area etching under the current dry etching process needs to be improved and the etching uniformity still needs to be enhanced, this utility model provides a plasma etching electrode.

[0005] The technical solution of this utility model is as follows:

[0006] A plasma etching electrode has a circular cross-section perpendicular to its central axis; an inner surface of the etching electrode is formed on the side facing the plasma chamber along the central axis, and an outer surface of the etching electrode is formed on the side outside the plasma chamber along the central axis; pores are distributed on the surface of the etching electrode, penetrating the outer and inner surfaces, and the diameter of the pores is between 0.35-0.5 mm.

[0007] Preferably, the pores are regularly distributed on the etched electrode in units of individual pores.

[0008] Preferably, the pores are densely packed in equilateral triangles or in regular quadrilaterals on the etched electrode.

[0009] Preferably, the pores extend in a ring shape from the central axis to the edge on the etched electrode; the pores in each ring are equally spaced, or the spacing between the rings increases and then decreases radially from the central axis to the edge.

[0010] Preferably, a group of pores is formed, and the group of pores extends in a ring shape from the central axis to the edge on the etched electrode; the pore groups in each ring are equally spaced, or the spacing between the rings increases and then decreases radially from the central axis to the edge.

[0011] Preferably, the etching electrode is divided into a circular inner region and an annular outer region located on the side of the inner region away from the central axis, with the central axis as the center; the pores in the inner region are provided with a first diameter, and the pores in the outer region are provided with a second diameter, the second diameter being smaller than the first diameter.

[0012] Preferably, the second diameter is 0.4 mm and the first diameter is 0.5 mm.

[0013] Preferably, the inner surface is a smooth curved surface with a smooth curved profile that protrudes at both ends and is concave in the middle along the radial direction from the center axial edge.

[0014] The etching electrode of this invention ensures stable gas delivery within each individual pore through its pore size design. This helps guarantee the stability and consistency of the gas delivered from the pores, thereby improving etching uniformity. Furthermore, the pore size design also considers the production efficiency of the etching electrode. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of a specific embodiment of the etching electrode 1 of this utility model.

[0016] In the picture:

[0017] 1: Etched electrode; 11: Outer surface; 12: Inner surface; 13: Pore; 14: Hole group; O: Central axis. Detailed Implementation

[0018] The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments. In this specification, the dimensions of the drawings do not represent the actual dimensions. They are only used to illustrate the relative positional and connection relationships between the components. Components with the same name or the same reference numeral represent similar or identical structures and are limited to illustrative purposes.

[0019] Figure 1 This is a schematic diagram of Embodiment 1 of this application. Since the wafer is circular, the plasma etching chamber also generally has a circular cross-section consistent with the wafer to ensure isotropic uniformity along the wafer circumference. Correspondingly, the etching electrode 1 has a circular cross-section perpendicular to its central axis. When the etching electrode 1 is in operation, it forms a plasma chamber with the limiting ring, counter electrode, etc. The surface along the axis facing into the plasma chamber is the inner surface 12 of the etching electrode 1, and the surface along the axis outside the plasma chamber is the outer surface 11 of the etching electrode 1. The etching electrode 1 is uniformly distributed with pores 13 penetrating both the outer surface 11 and the inner surface 12. During etching, gas passes through the pores 13. In the plasma chamber, an electric field is generated between the etching electrode 1 and the bottom counter electrode by a bias voltage, causing partial ionization of the gas in the plasma chamber to form plasma that bombards the wafer surface.

[0020] Generally, the etching depth of a wafer along the radial direction may be uneven due to edge effects. Furthermore, due to the instability of the gas intake, other locations on the wafer surface may also exhibit etching depth differences exceeding the standard. The uniformity of etching depth can be improved by controlling the vents 13 on the etching electrode 1. Firstly, the vents 13 should be uniformly distributed across the etching electrode 1, either evenly distributed on the surface of the etching electrode 1 or evenly distributed in groups on the surface of the etching electrode 1. To ensure the gas uniformity of a single vent 13, the diameter of the vent 13 is 0.35-0.5 mm. A smaller vent diameter primarily ensures the stability of gas flow; if the diameter is too large, the gas passing through the vent 13 may form stronger turbulence, leading to localized uneven etching. A smaller vent size is beneficial for stable gas delivery, and the overall uniformity of gas distribution can be ensured through the reasonable layout of the vents 13. Setting the minimum size to 0.35 mm is not only for process considerations but also to ensure the gas intake effect. In terms of manufacturing process, a smaller pore diameter means a smaller drill bit diameter. Therefore, the process design needs to prioritize preventing drill bit breakage, which can negatively impact drilling efficiency. Furthermore, a reduced pore diameter means that more pores (13) are required to meet the same air intake demand, which also affects drilling efficiency. In addition, during the sample verification phase, the applicant not only conducted production verification for electrodes with pore diameters of 0.35mm and 0.5mm, but also for electrodes with an intermediate pore size of 0.4mm.

[0021] The overall uniformity variation caused by systemic factors can be reduced through targeted shape design of the inner surface 12 of the etching electrode 1. Systemic distribution differences in plasma and applied electric field across a large cross-section can result in weaker etching at the center and edges. To compensate for this, the inner surface 12 of the etching electrode 1 can be modified from a planar design to a curved design based on the variation of etching depth from the center outwards. For example... Figure 1 As shown in section AA, the inner surface 12 has a smooth curved profile with convex ends and concave middle along the radial direction from the central axis O to the edge, which realizes etching depth compensation.

[0022] Regarding the pores 13, they can be regularly distributed on the etching electrode 1 as individual pores 13, for example, densely packed in equilateral triangles or squares, extending in a ring shape from the central axis O to the edge, with equal spacing between pores 13 within each ring. Pores 13 can also be arranged in groups, as shown in the figure, where three pores 13 form a group 14. Preferably, the group 14 extends in a ring shape from the central axis O to the edge, with equal spacing between group 14 within each ring. The spacing between rings can be equal, but preferably variable. By adjusting the spacing between rings, the density of the group 14 can be adjusted, thereby compensating for the non-uniformity of etching the electrode 1 under the original scheme. Therefore, the spacing between rings can be set to gradually increase to a maximum value from the central axis O to the edge for compensation purposes, and then optionally remain constant or gradually decrease.

[0023] Furthermore, preferably, the gas distribution is controlled by the diameter of the pores 13. For the annularly extended pores 13 or the hole group 14, the compensation function is achieved by using different diameters of the pores 13 between the rings. Specifically, the pores 13 are divided into outer and inner regions according to the position of the rings. A first diameter is set for the pores 13 in the outer region, and a second diameter is set for the pores 13 in the inner region. The second diameter is set to be smaller than the first diameter according to the compensation needs, so as to ensure that the gas supply near the central axis O of the inner layer is more sufficient per unit area, thereby improving the etching depth and ensuring etching uniformity. In this regard, based on the above range, the outer layer uses a diameter of 0.5 mm and the inner layer uses a diameter of 0.4 mm. The inner layer includes two rows of pores 13 extending to the central axis O, which can improve the consistency of the etching depth of the wafer.

[0024] The above description is merely a preferred embodiment of the present utility model and is not intended to limit the scope of the present utility model. Any modifications and improvements made to the technical solution of the present utility model by those skilled in the art without departing from the spirit of the present utility model should fall within the protection scope defined by the claims of the present utility model.

Claims

1. A plasma etching electrode, characterized in that, The etching electrode (1) has a circular cross section perpendicular to the central axis (O); the inner surface (12) of the etching electrode (1) is formed on the side facing the plasma chamber along the central axis (O), and the outer surface (11) of the etching electrode (1) is formed on the side outside the plasma chamber along the central axis (O); the surface of the etching electrode (1) is distributed with pores (13) that penetrate the outer surface (11) and the inner surface (12), and the diameter of the pores (13) is between 0.35-0.5 mm.

2. The plasma etching electrode as described in claim 1, characterized in that, The pores (13) are regularly distributed on the etching electrode (1) in units of individual pores (13).

3. The plasma etching electrode as described in claim 2, characterized in that, The pores (13) are densely packed on the etching electrode (1) in either equilateral triangles or in regular quadrilaterals.

4. The plasma etching electrode as described in claim 2, characterized in that, The pores (13) extend in a ring shape from the central axis (O) to the edge on the etching electrode (1); The pores (13) in each ring are equally spaced, or the spacing between the rings increases and then decreases radially from the central axis (O) towards the edge.

5. The plasma etching electrode as described in claim 1, characterized in that, A number of pores (13) form a hole group (14), which extends in a ring shape from the central axis (O) to the edge on the etching electrode (1); The holes (14) in each ring are equally spaced, or the spacing between the rings increases and then decreases radially from the central axis (O) towards the edge.

6. The plasma etching electrode as described in any one of claims 4 and 5, characterized in that, The etching electrode (1) is divided into a circular inner region and an annular outer region located on the side of the inner region away from the central axis (O) with the central axis (O) as the center. The pores (13) in the inner region are provided with a first diameter, and the pores (13) in the outer region are provided with a second diameter, the second diameter being smaller than the first diameter.

7. The plasma etching electrode as described in claim 6, characterized in that, The second diameter is 0.4 mm, and the first diameter is 0.5 mm.

8. The plasma etching electrode as described in claim 1, characterized in that, The inner surface (12) is a smooth curved surface with a smooth curved profile that is raised at both ends and recessed in the middle along the radial direction from the central axis (O) to the edge.

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