Improved plasma chamber electrode structure and plasma activation apparatus thereof

Abstract

The utility model relates to the field of semiconductor manufacturing technology discloses an improved plasma cavity electrode structure and its plasma activation equipment, including the lower electrode of setting in the plasma cavity, the positive face air channel groove of setting positive face air channel groove on the lower electrode upper surface, still having the hole of setting through the lower electrode, the positive face air channel groove is communicated with the hole and the hole is communicated with the cavity exhaust port, and the positive face air channel groove includes the following electrode center as the center, and the radial air channel groove of setting multiple pieces of radial air channel groove along the radial direction, and / or the following electrode center as the center, and the at least one annular groove of setting along the circumference direction, the lower electrode lower surface sets back air channel groove, and back air channel groove is communicated with the hole, compared with prior art, the utility model improves the lower electrode surface exhaust channel, optimizes the electrode surface and the back exhaust channel, and is communicated with the loading thimble hole position, guarantees that the gas between wafer and electrode can stably flow into the cavity exhaust port.

Description

Technical Field

[0001] This utility model relates to the field of semiconductor manufacturing technology, and in particular to an improved plasma cavity electrode structure and its plasma activation equipment. Background Technology

[0002] Before bonding, wafer bonding requires surface activation by a plasma module to lower the annealing temperature, improve the hydrophilicity of the wafer surface, and enhance pre-bonding strength. (See plasma module for details.) Figure 1 Capacitively coupled plasma (CCP) is generated by a radio frequency (RF) power supply creating a high-frequency electric field on the two electrodes of a parallel-plate capacitor. Initial electrons in the gas within the cavity gain energy under the influence of this electric field, bombarding gas molecules and producing more electrons, ions, and free radicals, forming a dynamically balanced low-temperature plasma. Plasma bombardment of the wafer surface breaks the covalent bonds, resulting in higher surface activity. After plasma bombardment, the wafer's surface activity and hydrophilicity increase, making it easier for hydroxyl groups to form on the wafer surface during subsequent cleaning processes. Following surface activation, the wafer can be annealed at lower temperatures to form covalent bonds, improving production efficiency and reducing thermal damage to the silicon wafer from high temperatures.

[0003] Because wafer position often shifts during the process of transferring the wafer to the lower electrode of the plasma module, see [link / reference]. Figure 2 When the wafer edge deviates from the focusing ring, the impedance increases, coupling lower RF power to the focusing ring region. This reduces the thickness of the plasma sheath region at the edge, distorting the edge sheath profile. More ions bombard the wafer edge, resulting in a thicker THK at the edge. Conversely, when the wafer edge is aligned with the focusing ring, the impedance decreases, coupling higher RF power to the focusing ring region. This increases the thickness of the plasma sheath region at the edge, leading to more ion bombardment and a thinner THK at the edge. This instability in the surface thickness (THK) uniformity of the plasma module during plasma processing results in poor activation uniformity, unstable bonding strength, and bonding defects at process boundaries.

[0004] Bonding defects refer to bonding defects that occur at the chip edges during the chip bonding process. These defects can affect the electrical performance and reliability of the chip. Uneven activation of electrical metal connection sites: In hybrid bonding, plasma treatment can remove oxides and other contaminants from the copper surface, making the surface clean and more active. If the copper pillar surface is not uniformly activated during the plasma process, it can lead to electrical connection defects at the bonding surface. Utility Model Content

[0005] Purpose of the utility model: To address the problems existing in the prior art, this utility model provides an improved plasma cavity electrode structure and its plasma activation equipment. The exhaust channels on the lower electrode surface are improved, the exhaust channels on the electrode surface and back are optimized, and they are connected to the loading pin holes to ensure that the gas between the wafer and the electrode can be stably drawn into the cavity exhaust port.

[0006] Technical solution: This utility model provides an improved plasma cavity electrode structure, including a lower electrode disposed in the plasma cavity. The upper surface of the lower electrode is provided with a front air passage groove, and a hole is also provided through the lower electrode. The front air passage groove is connected to the hole, and the hole is connected to the cavity exhaust port.

[0007] Furthermore, the front airway groove includes multiple radial airway grooves arranged radially with the center of the electrode as the center; and / or the front airway groove includes at least one annular groove arranged circumferentially with the center of the electrode as the center.

[0008] Furthermore, the width of the front air passage groove is greater than or equal to the diameter of the hole.

[0009] Furthermore, the width of the front airway groove is 3.5mm~4.5mm, the depth is 0.5~1.5mm, and the diameter of the hole is 1.5~2.5mm.

[0010] Furthermore, the holes are pin holes, and there are multiple pin holes arranged at intervals along the circumference of the lower electrode.

[0011] Furthermore, a back air channel groove is provided on the lower surface of the lower electrode. The back air channel groove is connected to the hole and the back air channel groove is aligned with the air channel direction of the quartz disk base disposed in the plasma cavity.

[0012] Furthermore, the back airway groove includes multiple radial airway grooves arranged radially with the electrode center as the center.

[0013] Furthermore, the width of the back air passage groove is greater than or equal to the diameter of the hole.

[0014] Furthermore, the width of the back airway groove is 3.5mm~4.5mm, the depth is 0.5~1.5mm, and the diameter of the hole is 1.5~2.5mm.

[0015] The present invention also discloses a plasma activation device, wherein the plasma activation device is provided with the improved plasma cavity electrode structure as described above.

[0016] Beneficial effects:

[0017] 1. Compared to traditional lower electrode structures, this invention features a gas channel groove on the upper surface of the lower electrode that connects to a hole through which P penetrates the lower electrode. Gas from the gas channel groove on the upper surface of the electrode can be transmitted through the hole, ensuring that the gas between the wafer and the electrode can stably flow into the cavity exhaust port. According to Bernoulli's equation in physics, in a closed system, the total energy of a non-viscous, incompressible fluid flowing along a streamline remains constant. When the fluid velocity increases, the static pressure decreases; conversely, when the fluid velocity decreases, the static pressure increases. When the airflow velocity increases, the static pressure P decreases, allowing the wafer to fall more stably onto the electrode, thus reducing slippage. The hole penetrating the lower electrode can be a pin-through hole, containing a ejector pin. No new hole structure is needed; the above objective can be achieved using existing pin-through holes, simplifying the structure and saving costs.

[0018] 2. Compared to the traditional lower electrode structure, this utility model provides radial and / or annular airway grooves, increasing the flow of gas through the airway. Furthermore, the annular grooves are connected to the radial airway grooves, which further enhances the flow of gas through the airway.

[0019] 3. Compared with the traditional lower electrode structure, the width of the gas channel groove in this utility model is designed to be greater than or equal to the diameter of the hole, and the size is increased to 3.5mm~4.5mm. Compared with the traditional 2mm size, it can accelerate the stable flow of gas between the wafer and the electrode into the cavity exhaust port, and reduce wafer slippage.

[0020] 4. This utility model also provides a gas channel groove on the back of the lower electrode. After passing through the hole, the gas passes through the gas channel groove on the back of the lower electrode. Because the gas channel groove is aligned with the gas channel of the quartz disk on the base of the plasma chamber, the gas can flow into the exhaust port of the chamber more quickly. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the overall structure of a traditional plasma chamber for wafer activation.

[0022] Figure 2 This is a schematic diagram of the plasma edge ion trajectory of the wafer at different positions on the lower electrode; where (a) is the case where the wafer is in the middle; and (b) is the case where the wafer has slid to the edge.

[0023] Figure 3 This is a schematic diagram of the modified structure of the upper surface of the lower electrode of the plasma cavity in Embodiment 1 of this utility model;

[0024] Figure 4 This is a schematic diagram of the modified structure of the upper surface of the lower electrode of the plasma cavity in Embodiment 2 of this utility model;

[0025] Figure 5This is a schematic diagram of the modified structure of the lower surface of the lower electrode of the plasma cavity of this utility model;

[0026] Figure 6 The images show a comparison of the lower electrode of the plasma chamber before and after the modification, where (a) is a top view of the upper surface of the lower electrode before modification; (b) is a top view of the upper surface of the lower electrode after modification; (c) is a bottom view of the lower surface of the lower electrode before modification; and (d) is a bottom view of the lower surface of the lower electrode after modification.

[0027] Figure 7 This is a schematic diagram of the wafer operating on the lower electrode according to this utility model;

[0028] Figure 8 Offline monitoring charts of THK after the improved design of the Plasma lower electrode of this utility model;

[0029] Figure 9 The images show a comparison of THK uniformity after the Plasma lower electrode design was improved. (a) shows the THK range of 5.19A before the lower electrode modification, and (b) shows the THK range of 0.69A after the modification.

[0030] Among them, 1-upper electrode, 2-lower electrode, 21-front air passage groove, 22-back air passage groove, 201-radial air passage groove A, 202-hole, 203-circular groove, 204-radial air passage groove B, 3-wafer, 4-RF source, 5-cavity exhaust port. Detailed Implementation

[0031] The present invention will now be described in detail with reference to the accompanying drawings.

[0032] In the description of this utility model, it should be understood that the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc., indicating the orientation or positional relationship are based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this utility model and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this utility model.

[0033] Implementation method 1:

[0034] This utility model discloses an improved plasma cavity electrode structure, see [link to relevant documentation]. Figure 3The system includes a lower electrode 2 disposed within the plasma chamber. A front airway groove 21 is provided on the upper surface of the lower electrode 2, and a hole 202 is also provided penetrating the lower electrode. The front airway groove communicates with the hole 202, and the hole 202 communicates with the chamber exhaust port 5. The width of the front airway groove 21 is greater than or equal to the diameter of the hole 202.

[0035] In this embodiment, the front airway groove 21 consists of multiple radial airway grooves A201 arranged radially, such as three radial airway grooves A201, but not limited to three. The holes 202 are pin holes, and the number of them is multiple, such as three, but not limited to three. The three pin holes are spaced apart along the circumference of the lower electrode. The three radial airway grooves 201 are respectively connected to the three pin holes. In this application, the radial airway groove refers to the groove extending from the center of the lower electrode surface to the edge in the overall extension direction. The shape of the airway groove can be a straight line, an arc, a broken line, etc., as long as gas flow is achieved. Smooth shapes such as straight lines and arcs that are conducive to stable gas flow are preferred.

[0036] In this embodiment, the radial airway groove 201 has a width of 3.5mm to 4.5mm and a depth of 1mm. The pin hole 202 has a diameter of 2mm.

[0037] Implementation Method 2:

[0038] The difference between this embodiment and Embodiment 1 is that the front air passage groove 21 includes at least one annular groove 203 centered on the center of the upper surface of the lower electrode 2. The annular groove can overlap and communicate with the hole in the top view direction of the upper surface of the lower electrode (not shown in the figure), or it can communicate with the hole through a radial air passage groove. In this application, the annular groove refers to a groove whose overall extension direction surrounds the center of the lower electrode surface. The shape of the annular groove can be various, as long as gas flow is achieved. A circular annular groove that is conducive to stable gas flow is preferred.

[0039] See Figure 4 In this embodiment, two annular grooves 203 are equidistantly arranged on the upper surface of electrode 2 with the center as the center, but not limited to two. The width of the annular grooves 203 is 3.5mm~4.5mm and the depth is 1mm.

[0040] Implementation Method 3:

[0041] The difference between this embodiment and embodiment 2 is that, based on embodiment 2, a back airway groove 22 is also provided on the lower surface of the lower electrode 2. In this embodiment, the back airway groove 22 consists of multiple radial airway grooves B204 arranged radially, such as three radial airway grooves B204, but not limited to three. The three radial airway grooves B204 are respectively connected to the three through holes 202. The width of the radial airway grooves B204 is 3.5mm~4.5mm, and the depth is 1mm. The radial airway grooves B204 on the lower surface of the lower electrode 2 are aligned with the airway direction of the quartz disk (not shown in the figure) on the base of the plasma chamber. The improved lower electrode structure in this embodiment is compared with the traditional lower electrode structure as follows: Figure 6 (a) is a top view of the upper surface of the lower electrode before modification; (b) is a top view of the upper surface of the lower electrode after modification; (c) is a bottom view of the lower surface of the lower electrode before modification; (d) is a bottom view of the lower surface of the lower electrode after modification.

[0042] Implementation Method 4:

[0043] This embodiment discloses a plasma activation device, which is provided with any of the improved plasma cavity electrode structures in embodiments 1 to 4. Other structures are conventional plasma activation device structures, which are not the focus of this utility model and will not be described in detail here.

[0044] After the above modifications, taking the lower electrode structure of Embodiment 3 as an example, it was applied to a plasma activation device for experimentation. See [link to related documentation]. Figure 8 The THK offline monitoring chart shows the maximum and minimum activation thickness of the wafer surface after plasma treatment on the vertical axis, and the number of experiments on the horizontal axis. After the improvement of the gas channel trench in the lower electrode 2, the difference in the activation thickness of the wafer surface gradually decreases. See [link to THK offline monitoring chart]. Figure 9 The THK range of the lower electrode before the improvement was 5.19A, and the THK range of the lower electrode after the improvement was 0.69A. This shows that the improved lower electrode structure can better improve the THK uniformity.

[0045] The above embodiments are only for illustrating the technical concept and features of this utility model, and are intended to enable those skilled in the art to understand the content of this utility model and implement it accordingly. They should not be construed as limiting the scope of protection of this utility model. All equivalent transformations or modifications made in accordance with the spirit and essence of this utility model should be included within the scope of protection of this utility model.

Claims

1. An improved plasma cavity electrode structure, comprising a lower electrode disposed within a plasma cavity, characterized in that, The upper surface of the lower electrode is provided with a front airway groove, and a hole is also provided through the lower electrode. The front airway groove is connected to the hole and the hole is connected to the cavity exhaust port. The front airway groove includes multiple radial airway grooves arranged radially with the center of the lower electrode as the center. And / or the front airway groove includes at least one annular groove arranged circumferentially with the center of the electrode as the center.

2. The improved plasma cavity electrode structure according to claim 1, characterized in that, The width of the front air passage groove is greater than or equal to the diameter of the hole.

3. The improved plasma cavity electrode structure according to claim 2, characterized in that, The width of the front airway groove is 3.5mm~4.5mm, the depth is 0.5~1.5mm, and the diameter of the hole is 1.5~2.5mm.

4. The improved plasma cavity electrode structure according to claim 1, characterized in that, The holes are pin holes, and there are multiple pin holes, which are spaced apart along the circumference of the lower electrode.

5. The improved plasma cavity electrode structure according to claim 1, characterized in that, The lower surface of the lower electrode is provided with a back air channel groove, which is connected to the hole and the back air channel groove is aligned with the air channel of the quartz disk of the base in the plasma chamber.

6. The improved plasma cavity electrode structure according to claim 5, characterized in that, The back airway groove includes multiple radial airway grooves arranged radially with the center of the electrode as the center.

7. An improved plasma cavity electrode structure according to claim 5, characterized in that, The width of the air passage groove on the back is greater than or equal to the diameter of the hole.

8. The improved plasma cavity electrode structure according to claim 7, characterized in that, The width of the back airway groove is 3.5mm~4.5mm, the depth is 0.5~1.5mm, and the diameter of the hole is 1.5~2.5mm.

9. A plasma activation device, characterized in that, The plasma activation device is provided with an improved plasma cavity electrode structure as described in any one of claims 1 to 8.

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