Compact wafer-level high-precision metal auxiliary chemical etching equipment

Abstract

The invention discloses compact wafer-level high-precision metal-assisted chemical etching equipment, which relates to the field of microelectronic manufacturing, is suitable for small-scale metal-assisted chemical etching experiment or production on the surface of a substrate material, can be conveniently expanded into multi-cavity equipment by a single cavity, allows a plurality of wafers to be processed at the same time by a multi-cavity parallel framework, and is suitable for large-scale metal-assisted chemical etching. Compared with traditional single-cavity or groove type equipment, the yield per unit time can be increased by several times. And each cavity is provided with an independent fluid system, so that the consistency of the etching rate and the morphology and high etching precision are ensured. Compared with a traditional groove type device in which multiple wafers share the same reaction environment, the multi-cavity design effectively avoids the fringe effect and the difference in batches. The device has the advantages of being small in size, low in manufacturing cost, simple in structure and short in production period, and the requirement for high-uniformity metal auxiliary etching can be met.

Description

Technical Field

[0001] This invention relates to a compact wafer-level high-precision metal-assisted chemical etching device, belonging to the field of microelectronics manufacturing technology. Background Technology

[0002] Metal-assisted chemical etching (MaCE), a wet etching technique, holds significant application value in the semiconductor and microelectromechanical systems (MEMS) fields due to its ability to fabricate high aspect ratio micro / nano structures. The core mechanism of this technology lies in accelerating the etching reaction of silicon using a noble metal catalyst (such as Au or Ag) deposited on the substrate surface within the etching solution, thereby achieving directional and selective etching of the substrate material. Notably, the trajectory of the metal catalyst directly determines the etching direction, making the control of catalyst movement a critical parameter in the MaCE process. In MaCE, the etching solution needs continuous flow to enhance the diffusion of chemical components and accelerate the etching rate; however, the flow rate cannot be too high to avoid affecting the trajectory of the metal catalyst.

[0003] Currently, there is no high-precision wafer-level etching equipment specifically designed for the MaCE process. Similar wet etching equipment typically includes transport pipelines, large solution pumps, control systems, and valves, which are not only cumbersome to operate and maintain, but also have a large footprint, long production cycles, and high costs. Furthermore, they generally lack precise flow rate control capabilities, making them unsuitable for wafer-level metal-assisted chemical etching (MACE). Therefore, this patent, based on the characteristics of metal-assisted chemical etching, specifically designs a compact wafer-level high-precision metal-assisted chemical etching equipment, featuring small size, low cost, simple structure, and short production cycle. Summary of the Invention

[0004] Objective: To achieve high-precision, high-throughput MaCE etching, this invention provides a compact wafer-level high-precision metal-assisted chemical etching (MACE) device. It features small size, low cost, simple structure, and short production cycle, meeting the requirements for high-uniformity metal-assisted etching. It is suitable for small-scale metal-assisted chemical etching experiments or production on substrate material surfaces (silicon wafers, glass, ceramics). A single cavity can be easily expanded into a multi-cavity device to simultaneously etch multiple wafers, meeting high-throughput production needs. Fluid control within each cavity ensures the uniformity of each wafer.

[0005] Technical solution: To solve the above technical problems, the technical solution adopted by the present invention is as follows:

[0006] A compact wafer-level high-precision metal-assisted chemical etching (MaCE etching) apparatus is disclosed. The etching target is a wafer substrate with a surface covered by a metal catalyst film and a passivation layer film. The passivation layer film is used to cover the surface of non-etched areas to prevent etching in those areas. The etching medium is a solution containing oxidant, acid, and other components. The apparatus consists of a microcavity, a circulation tank, and a solution pump. The microcavity and the circulation tank are connected by a pipeline. The microcavity has a specific geometry to provide space for wet etching of the substrate and to control the flow field of the solution. The solution pump is installed on the pipeline to control the flow rate of the etching solution.

[0007] As a preferred embodiment, the device features a compact etching chamber with an inner and outer cavity design. This chamber provides the necessary etching solution flow field control for MaCE etching, ensuring a specific velocity distribution of the fluid flowing across the substrate surface for high-precision etching. The microcavity comprises an outer cavity and an inner cavity. The inner cavity is housed within the outer cavity, with a drain outlet between them. The bottom of the outer cavity has an inlet communicating with the inner cavity, and a flow equalization plate is located at the bottom of the inner cavity. A substrate clamp is also detachably connected within the inner cavity. The inner cavity is constructed from corrosion-resistant materials such as polytetrafluoroethylene, polyetheretherketone, and polyvinylidene fluoride, capable of withstanding solutions and mixtures of hydrofluoric acid, sulfuric acid, nitric acid, potassium permanganate, and hydrogen peroxide without corrosion.

[0008] As a preferred embodiment, a boss is provided at the bottom edge of the inner cavity. This boss and the flow equalization plate form a buffer cavity for the solution, so that the solution flow rate in the substrate etching area is uniform.

[0009] As a preferred embodiment, the inner walls on both sides of the inner cavity are provided with slots for fixing the substrate fixture to ensure that the substrate does not move in the flowing etching solution.

[0010] As a preferred embodiment, the top of the inner cavity is provided with a notch, from which the etching fluid flows out, ensuring a stable flow rate in the substrate etching area.

[0011] As a preferred embodiment, the substrate fixture includes an upper cover and a lower cover; the upper cover has a perforated through-hole for controlling the flow of the etching solution, and the front edge of the perforated through-hole has a rounded transition area; the back of the perforated through-hole has a first sealing ring groove; the front of the lower cover has a substrate groove and a second sealing ring groove arranged sequentially from the outside to the inside, the substrate groove being used to place the substrate material; sealing rings are provided in the first sealing ring groove and the second sealing ring groove; both the upper and lower covers have mounting holes, and the upper and lower covers are fixed to the substrate with screws through the mounting holes; the perforated through-hole on the front of this fixture is the substrate etching area, and the sealing rings ensure that etching only occurs in the fixed area, protecting other areas of the substrate from corrosion by the etching solution.

[0012] As a preferred embodiment, the flow equalization plate is uniformly provided with flow equalization holes to control the flow velocity distribution in the substrate etching area.

[0013] As a preferred embodiment, the microcavity includes a main cavity, on which multiple pairs of clamping parts can be provided on the inner walls of both sides. Each pair of adjacent clamping parts on one side is provided with a flow equalization plate slot. A liquid inlet hole is provided on one side of the inner wall of the main cavity between two adjacent clamping parts on one side, and a liquid outlet hole is provided on the inner wall of the other side of the main cavity. A flow equalization plate is clamped on the adjacent flow equalization plate slot, and a substrate clamp is clamped on a pair of clamping parts.

[0014] As a preferred option, a dedicated solution heating device is provided, which can increase the MaCE etching reaction rate by controlling the solution temperature.

[0015] As a preferred embodiment, multiple liquid inlet holes are provided on one side of the inner wall of the main cavity between two adjacent clamping parts on one side, and multiple liquid outlet holes are provided on the other side of the inner wall of the main cavity; it has a dedicated high-precision, corrosion-resistant solution delivery pump with a flow control range of 10^-6 L / s to 1000 L / s, which can be adjusted with the etching time. The adjustment method includes manual or automatic, thereby ensuring that the flow rate of the etching solution on the wafer surface can be controlled at different etching stages.

[0016] Beneficial effects: The compact wafer-level high-precision metal-assisted chemical etching equipment provided by this invention has the following advantages compared with the prior art:

[0017] (1) Compact main structure. Compared with traditional cavity wet etching equipment, the micro-cavity (hereinafter referred to as micro-cavity) is used for processing. The size of the micro-cavity fits the shape of the substrate, reducing the ineffective volume. It includes a micro-cavity body with a concave cavity and a top opening. The micro-cavity body is provided with a liquid inlet and a liquid outlet; a substrate clamp is used to protect the back side of the substrate so that the back side is not etched; a fluid circulation tank is used to collect the solution in the micro-cavity. Then the solution pump draws out the solution and injects it back into the micro-cavity for recycling, realizing low consumption of etching solution.

[0018] (2) The substrate fixture has a specially designed sealing structure to seal the edges according to the shape of the substrate. The main body of the fixture acts as a rigid support layer, and sealing rings or gaskets are used as elastic contact layers. It can control the size and shape of the area on the substrate surface to be etched, while ensuring that the etching solution does not leak, thereby ensuring the safety and stability of other components of the equipment and other non-etched areas of the substrate. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the structure of a first embodiment of a compact wafer-level high-precision metal-assisted chemical etching apparatus according to the present invention.

[0020] Figure 2 This is a schematic diagram of the structure of the microcavity according to the first embodiment of the present invention.

[0021] Figure 3 This is a top view schematic diagram of the microcavity according to the first embodiment of the present invention.

[0022] Figure 4 This is a schematic diagram of the substrate fixture according to a first embodiment of the present invention. Figure 4 Image (a) is a front view of the top cover. Figure 4 Image (b) is a schematic diagram of the back of the top cover. Figure 4 Image (c) is a front view of the lower cover. Figure 4 The middle (d) is a schematic diagram of the back of the lower cover.

[0023] Figure 5 This is a schematic diagram of the flow uniform plate according to the first embodiment of the present invention.

[0024] Figure 6 This is a schematic diagram of a second embodiment of a compact wafer-level high-precision metal-assisted chemical etching apparatus according to the present invention. Figure 6 (a) is a top view, (b) is a side view, and (c) is an oblique view.

[0025] Figure 7 This is a schematic diagram of the structure of the microcavity according to the second embodiment of the present invention.

[0026] Figure 8 This is a schematic diagram of the liquid inlet and liquid outlet of the microcavity in the second embodiment of the present invention.

[0027] Figure 9 This is a schematic diagram of the flow equalization plate at the liquid inlet in a second embodiment of the present invention.

[0028] Figure 10 This is a schematic diagram of the flow equalization plate at the drain outlet in the second embodiment of the present invention. Detailed Implementation

[0029] The technical solutions 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 protection scope of the present invention.

[0030] The present invention will be further described below with reference to specific embodiments.

[0031] Example 1:

[0032] This embodiment describes a first embodiment of a compact wafer-level high-precision metal-assisted chemical etching apparatus, such as... Figure 1 As shown, it includes a micro chamber 1, a circulation tank 2, and a solution pump 3. The micro chamber 1, the circulation tank 2, and the solution pump 3 are connected by a pipeline 4. Valves 5 are installed on the inlet and outlet pipes of the micro chamber 1.

[0033] Furthermore, such as Figure 2 As shown, the microcavity 1 includes: an outer cavity 101 and an inner cavity 102. The inner cavity 102 is disposed inside the outer cavity 101. A drain port 103 is disposed between the outer cavity 101 and the inner cavity 102. A liquid inlet 104 communicating with the inner cavity 102 is disposed at the bottom of the outer cavity 101. A flow equalization plate 6 is disposed at the bottom of the inner cavity 102. A substrate clamp 7 is detachably connected inside the inner cavity 102.

[0034] Furthermore, such as Figure 3 As shown, a boss 105 is provided at the bottom edge of the inner cavity 102 for placing the flow equalizer 6, so that there is space for solution to flow in between the flow equalizer 6 and the liquid inlet 104.

[0035] Furthermore, slots 107 are provided on the inner walls on both sides of the inner cavity 102 for placing the substrate clamp 7.

[0036] Furthermore, a notch 106 is provided at the top of the inner cavity 102 to facilitate the flow of the solution inside the inner cavity 102 into the outer cavity 101.

[0037] Furthermore, multiple pairs of slots 107 are provided on the inner walls on both sides of the inner cavity 102 for placing multiple sets of substrate fixtures 7 to achieve simultaneous etching of multiple substrates.

[0038] Furthermore, the number of liquid inlets 104 and liquid outlets 103 are both set to be multiple to accelerate the circulation of the solution.

[0039] Furthermore, the liquid inlet 104 and the liquid outlet 103 are configured as bottom-contracting liquid collection hopper structures to enhance the liquid collection and drainage capacity.

[0040] Furthermore, the inlet 104 and outlet 103 are also equipped with spiral guide vanes to enhance the liquid collection and drainage capacity.

[0041] Furthermore, the valve 5 is a corrosion-resistant spherical external thread pagoda head valve with a switch.

[0042] Furthermore, the pipeline 4 is made of corrosion-resistant rubber tubing.

[0043] Furthermore, the substrate clamp 7 includes: an upper cover 701 and a lower cover 702, as shown below. Figure 4As shown in (a), the upper cover 701 is provided with a perforated through hole 703, and the front edge of the perforated through hole 703 is provided with an arc transition area 704, which is used for better solution flow. Figure 4 As shown in (b), a first sealing ring groove 705 is provided on the back side of the hollow through hole 703. Figure 4 As shown in (c) and (d), the front side of the lower cover 702 is provided with a substrate groove 706 and a second sealing ring groove 707 from the outside to the inside. The substrate groove is used to place the substrate. Sealing rings are provided in the first sealing ring groove 705 and the second sealing ring groove 707. The upper cover 701 and the lower cover 702 are both provided with mounting holes 708, and the upper cover and the lower cover are fixed to each other with screws through the mounting holes.

[0044] Furthermore, such as Figure 5 As shown, the flow equalization plate 6 is uniformly provided with flow equalization holes 601. The number of flow equalization holes is increased or decreased according to biomimetic fluid dynamics. The shape of the flow equalization holes includes but is not limited to circular, square, triangular, conical, hexagonal and star-shaped. The flow equalization holes are arranged in a hexagonal close-packed array or other arrangements.

[0045] Furthermore, the gray portion of the circulating tank 2 is a schematic diagram of the heating belt winding, representing a solution heating device. This device can increase the MaCE etching reaction rate by controlling the solution temperature.

[0046] In a first embodiment of a compact wafer-level high-precision metal-assisted chemical etching apparatus, the substrate material is placed on the substrate groove 706 of the lower cover 702 of the substrate fixture 7, and then the upper cover 701 is closed and secured with screws. The fully enclosed substrate fixture design provides dual protection through physical isolation and hermetical sealing of the back side, preventing etching of the back side of the substrate. The fixed substrate fixture 7 is then snapped into the slot 107 of the inner cavity 102. The solution pump is turned on, and the etching solution is drawn from the circulation tank, enters through pipes and valves from the inlet at the bottom of the inner cavity 102, and then wet-etches the substrate material (such as surface silicon wafers, glass, or ceramics) within the inner cavity 102 via the flow equalization plate 6. The etched liquid flows out of the inner cavity 102, exits through the drain port on the outer cavity 101, and flows back to the circulation tank through pipes, achieving the recycling of the etching solution and flow etching.

[0047] Example 2:

[0048] This embodiment describes a second embodiment of a compact wafer-level high-precision metal-assisted chemical etching apparatus, such as... Figure 6As shown, the system includes a microcavity 1, a circulation tank 2, a drain pump 8, and an inlet pump 9. One side of the microcavity 1 is connected to the outlet of the inlet pump 9 via a pipeline, and the other side of the microcavity 1 is connected to the inlet of the drain pump 8 via a pipeline. The other ends of the inlet pump 9 and the drain pump 8 are respectively connected to the circulation tank 2 via pipelines. In the second embodiment, each pipeline is equipped with a corrosion-resistant valve to control the flow rate of each cavity, thereby regulating the flow rate of the etching solution on each wafer surface.

[0049] Furthermore, the microcavity, such as Figure 7 As shown, it includes: a main cavity 108, on which multiple pairs of clamping parts 109 are provided on the inner walls of both sides of the main cavity 108; on each of the two adjacent clamping parts 109 on one side, a flow equalization plate slot 110 is provided; on the inner wall of one side of the main cavity 108 between the two adjacent clamping parts 109 on one side, a liquid inlet hole 104 is provided; on the inner wall of the other side of the main cavity, a liquid outlet hole 103 is provided; a flow equalization plate 6 is clamped on the adjacent flow equalization plate slot 110; and a substrate clamp 7 is clamped on a pair of clamping parts.

[0050] Furthermore, such as Figure 8 As shown, a plurality of liquid inlet holes 104 are provided on one side of the inner wall of the main cavity 108 between two adjacent clamping parts 109 on one side, and a plurality of liquid outlet holes 103 are provided on the other side of the inner wall of the main cavity.

[0051] Furthermore, such as Figure 9 , Figure 10 As shown, the density of the flow equalization holes 601 of the flow equalization plate 6 at the liquid inlet is equal to the density of the flow equalization holes 601 of the flow equalization plate 6 at the liquid outlet.

[0052] Furthermore, the main cavity 108 is made of corrosion-resistant polytetrafluoroethylene material.

[0053] A second embodiment of a compact wafer-level high-precision metal-assisted chemical etching apparatus involves placing multiple substrate materials on the substrate grooves 706 of the lower covers 702 of multiple substrate clamps 7. The upper cover 701 is then placed on top and secured with screws. The fully enclosed substrate clamp design provides dual protection through physical isolation and gas-tight sealing of the back side, preventing etching of the back side of the substrate. The fixed substrate clamps 7 are then snapped between a pair of clamping parts 109 of the main cavity 108. The inlet and outlet pumps are turned on. The inlet pump draws the solution from the circulation tank and flows it evenly into the microcavity through a six-way diversion valve. Five substrate materials are simultaneously fixed in the microcavity for wet etching. Ten flow equalizers are held in place by a fixing structure and evenly positioned at the inlet and outlet. The outlet pump generates negative pressure to evenly extract the etching solution from the microcavity and discharges the solution back into the fluid circulation tank, achieving the recycling of the etching solution and flow etching.

[0054] This invention provides a compact wafer-level high-precision metal-assisted chemical etching apparatus, relating to the field of microelectronics manufacturing. Specifically, it discloses a miniaturized wet etching system characterized by small size, low cost, simple structure, and short production cycle, meeting the requirements for high-uniformity metal-assisted etching. It is suitable for small-scale wet etching experiments or production on substrate material surfaces (silicon wafers, glass, ceramics). A single cavity can be easily expanded into a multi-cavity device, and the multi-cavity parallel architecture allows for the simultaneous processing of multiple wafers, increasing throughput by several times compared to traditional single-cavity or tank-type equipment. Each cavity is equipped with an independent fluid system, allowing real-time adjustment of parameters (such as flow rate, pressure, and temperature) for different wafers, ensuring consistency in etching rate and morphology. Compared to traditional tank-type equipment where multiple wafers share the same reaction environment, the multi-cavity design effectively avoids edge effects and batch-to-batch variations. (Compared to traditional tank etching, fluid control capability is significantly improved.)

[0055] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A compact wafer-level high-precision metal-assisted chemical etching (hereinafter referred to as MaCE etching) device, characterized in that: The etching target is a wafer substrate with a metal catalyst film and a passivation layer film on its surface; the passivation layer film is used to cover the surface of the non-etched area so that the area is not etched; the etching medium is a solution containing oxidant, acid and other components; the equipment consists of a microcavity, a circulation tank and a solution pump, and the microcavity and the circulation tank are connected by a pipeline. The microcavity has a specific geometry to provide space for wet etching of the substrate and to control the flow field of the solution; a solution pump is installed on the pipeline to control the flow rate of the etching solution.

2. The compact wafer-level high-precision metal-assisted chemical etching equipment according to claim 1, characterized in that: The device features a compact etching chamber with an inner and outer cavity design. This chamber provides the necessary etching solution flow field control for MaCE etching, ensuring a specific velocity distribution of the fluid flowing across the substrate surface for high-precision etching. The micro-cavity comprises an outer cavity and an inner cavity. The inner cavity is housed within the outer cavity, with a drain outlet between them. An inlet communicating with the inner cavity is located at the bottom of the outer cavity, and a flow equalizer is positioned at the bottom of the inner cavity. A substrate clamp is detachably connected within the inner cavity. The inner cavity is constructed from corrosion-resistant materials such as polytetrafluoroethylene, polyetheretherketone, and polyvinylidene fluoride, capable of withstanding solutions and mixtures of hydrofluoric acid, sulfuric acid, nitric acid, potassium permanganate, and hydrogen peroxide without corrosion.

3. The compact wafer-level high-precision metal-assisted chemical etching equipment according to claim 2, characterized in that: The bottom edge of the inner cavity is provided with a protrusion, which together with the flow equalization plate forms a buffer cavity for the solution, so that the solution flow rate in the substrate etching area is uniform.

4. The compact wafer-level high-precision metal-assisted chemical etching equipment according to claim 2, characterized in that: The inner walls on both sides of the inner cavity are provided with slots for fixing the substrate fixture to ensure that the substrate does not move in the flowing etching solution.

5. A compact wafer-level high-precision metal-assisted chemical etching apparatus according to claim 2, characterized in that: The top of the inner cavity is provided with a notch, from which the etching fluid flows out, ensuring a stable flow rate in the substrate etching area.

6. The compact wafer-level high-precision metal-assisted chemical etching equipment according to claim 2, characterized in that: The substrate fixture includes an upper cover and a lower cover. The upper cover has a perforated through-hole for controlling the flow of the etching solution, and the front edge of the perforated through-hole has a rounded transition area. A first sealing ring groove is provided on the back of the perforated through-hole. The front of the lower cover has a substrate groove and a second sealing ring groove arranged sequentially from the outside to the inside. The substrate groove is used to place the substrate material. Sealing rings are provided in the first and second sealing ring grooves. Both the upper and lower covers have mounting holes, and the upper and lower covers are fixed to each other with screws through the mounting holes. The perforated through-hole on the front of this fixture is the substrate etching area, and the sealing rings ensure that etching only occurs in the fixed area, protecting other areas of the substrate from corrosion by the etching solution.

7. A compact wafer-level high-precision metal-assisted chemical etching apparatus according to claim 2, characterized in that: The flow equalization plate is uniformly provided with flow equalization holes to control the flow velocity distribution in the substrate etching area.

8. A compact wafer-level high-precision metal-assisted chemical etching apparatus according to claim 1, characterized in that: The microcavity includes a main cavity. Multiple pairs of clamping parts can be provided on the inner walls of both sides of the main cavity. Each pair of adjacent clamping parts on one side is provided with a flow equalization plate slot. A liquid inlet hole is provided on one side of the inner wall of the main cavity between two adjacent clamping parts on one side. A liquid outlet hole is provided on the other side of the inner wall of the main cavity. A flow equalization plate is clamped on the adjacent flow equalization plate slot. A substrate clamp is clamped on a pair of clamping parts.

9. A compact wafer-level high-precision metal-assisted chemical etching apparatus according to claim 8, characterized in that: It has a dedicated solution heating device, which can increase the MaCE etching reaction rate by controlling the solution temperature.

10. A compact wafer-level high-precision metal-assisted chemical etching apparatus according to claim 8, characterized in that: Multiple liquid inlet holes are provided on one side of the inner wall of the main cavity between two adjacent clamping parts, and multiple liquid outlet holes are provided on the other side of the inner wall of the main cavity; it has a dedicated high-precision, corrosion-resistant solution delivery pump with a flow control range of 10^-6 L / s to 1000 L / s, which can be adjusted with the etching time. The adjustment method includes manual or automatic, so as to ensure that the flow rate of the etching solution on the wafer surface can be controlled at different etching stages.

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