Infrared thermal imaging MEMS wafer cutting protection method and wafer cutting protection structure
By coating the surface of infrared thermal imaging MEMS wafers with hydrophobic photoresist and modifying it into a nano-coating, the problem of particle introduction during the dicing process was solved, improving the packaging yield and reducing environmental pollution.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- SUZHOU ZERO PERCEPTION TECH CO LTD
- Filing Date
- 2023-02-14
- Publication Date
- 2026-05-19
AI Technical Summary
Infrared thermal imaging MEMS wafers are prone to introducing particles during the dicing process, which affects the packaging yield and is difficult to solve effectively with existing technologies.
Photoresist is coated onto the surface of a MEMS wafer and modified to be hydrophobic. A nano-coating is then formed by coating it with a silicon-based or fluorine-based hydrophobic electronic solution. Particles introduced during dicing are easily washed away by cooling water, eliminating the need for wet cleaning processes on individual chips.
It effectively curbs particle contamination on wafer surfaces, improves packaging yield, reduces the use of organic solvents, and reduces environmental hazards.
Smart Images
Figure CN116281836B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to a wafer dicing protection method, and more particularly to an infrared thermal imaging MEMS wafer dicing protection method and wafer dicing protection structure. Background Technology
[0002] With the rapid development of optoelectronic imaging technologies such as infrared thermal imaging, infrared focal plane detectors have begun to be applied in large quantities to the military market and civilian markets such as security, power temperature measurement, industrial monitoring, consumer electronics, and automotive driver assistance.
[0003] Infrared focal plane array chips are the core components of detectors. They are made by integrating the focal plane array onto a silicon-based readout circuit using MEMS technology. Infrared thermal imaging MEMS wafers have various micromechanical structures such as cantilever beams, thin films, and sacrificial layers. These micromechanical structures are easily damaged by mechanical contact or contaminated by exposure.
[0004] Silicon wafer dicing is a key process for packaging infrared MEMS devices, and traditional blade dicing remains the most widely used method. Blade dicing is prone to problems such as chipping, micro-damage, and cracks on both sides, while also causing microparticle contamination from debris. These problems are difficult to completely solve by improving the dicing process itself.
[0005] As the size of a single pixel in an infrared focal plane array chip becomes smaller and smaller, the tolerance for particle size also becomes smaller and smaller. The common method is to cut the wafer into individual chips and then perform ultrasonic organic cleaning. However, the addition of cleaning process steps leads to the introduction of other defects. It is urgent to solve the problem of particles introduced during the cutting of infrared thermal imaging MEMS wafers, so as to improve the packaging yield. Summary of the Invention
[0006] The technical problem solved by this invention is to provide a method for protecting infrared thermal imaging MEMS wafers during dicing, overcoming the technical problem that particles are easily introduced during the dicing of infrared thermal imaging MEMS wafers in existing technologies, which in turn affect the packaging yield.
[0007] The technical solution of this invention is: to provide a method for protecting infrared thermal imaging MEMS wafers during dicing, comprising the following steps:
[0008] Constructing a MEMS structure: The infrared thermal imaging MEMS wafer includes a silicon substrate, an infrared readout circuit disposed on the silicon substrate, and a MEMS structure constructed on top of the infrared readout circuit;
[0009] Photoresist coating: Photoresist is coated on the surface of the MEMS structure on the silicon-based wafer;
[0010] Modifying the photoresist surface to a hydrophobic state: applying a silicon-based or fluorine-based hydrophobic electronic solution to the photoresist surface to form a coating, wherein the silicon-based or fluorine-based hydrophobic electronic solution modifies the photoresist surface to a hydrophobic state, such that the contact angle between the modified photoresist surface and the crystal plane is greater than 100 degrees.
[0011] Cutting: The infrared thermal imaging MEMS wafer is cut.
[0012] A further technical solution of the present invention is: the silicon-based or fluorine-based hydrophobic electronic solution is applied to the surface of the photoresist by spin coating or spray coating.
[0013] A further technical solution of the present invention is that the silicon-based or fluorine-based hydrophobic electronic solution forms a nano-coating on the photoresist surface.
[0014] A further technical solution of the present invention is that the thickness of the nano-coating formed by the silicon-based or fluorine-based hydrophobic electronic liquid is 10 nm to 100 nm.
[0015] A further technical solution of the present invention is that the contact angle between the modified photoresist surface and the crystal plane is 100 degrees to 125 degrees.
[0016] A further technical solution of the present invention is that the photoresist is applied to the upper surface of the infrared thermal imaging MEMS wafer by spin coating.
[0017] A further technical solution of the present invention is that the photoresist has a thickness of 1 micrometer to 2 micrometers.
[0018] The technical solution of this invention is: an infrared thermal imaging MEMS wafer dicing protection structure, comprising a silicon substrate, an infrared readout circuit disposed on the silicon substrate, a MEMS structure integrated on the infrared readout circuit, a photoresist layer disposed on the MEMS structure, and a chemical coating layer coated on the photoresist layer. A MEMS structure is constructed on top of the infrared readout circuit of the silicon substrate wafer to form a crystal plane. Photoresist is coated on the upper surface of the MEMS structure to form a photoresist layer. A silicon-based or fluorine-based hydrophobic electronic chemical coating is applied to the photoresist surface to form a coating layer. The silicon-based or fluorine-based hydrophobic electronic chemical coating modifies the photoresist surface to a hydrophobic state, such that the contact angle between the modified photoresist surface and the crystal plane is greater than 100 degrees.
[0019] A further technical solution of the present invention is that the thickness of the nano-coating formed by the silicon-based or fluorine-based hydrophobic electronic liquid is 10 nm to 100 nm.
[0020] A further technical solution of the present invention is that the silicon-based or fluorine-based hydrophobic electronic solution forms a nano-coating on the photoresist surface.
[0021] The technical effect of this invention is to provide a method and structure for protecting infrared thermal imaging MEMS wafers during dicing, comprising the following steps: the infrared thermal imaging MEMS wafer includes a silicon-based infrared readout circuit and a MEMS structure integrated on the circuit; a MEMS structure is constructed on one side of the silicon-based wafer to form a crystal plane; photoresist is coated on the crystal plane of the silicon-based wafer; a silicon-based or fluorine-based hydrophobic electronic solution is applied to the surface of the photoresist to form a coating; the silicon-based or fluorine-based hydrophobic electronic solution modifies the surface of the photoresist to a hydrophobic state, such that the contact angle between the modified photoresist surface and the crystal plane is greater than 100 degrees; and the infrared thermal imaging MEMS wafer is diced. This invention discloses a method for protecting infrared thermal imaging MEMS wafers during dicing. The wafer surface is protected by photoresist and is hydrophobic. Particles introduced during wafer dicing are easily washed away by cooling water, effectively preventing particle contamination on the wafer surface. Furthermore, the introduced protective layer does not alter the material properties of the MEMS structure itself. The protective layer is removed along with the dry release step of the infrared chip sacrificial layer. Compared with existing technologies, this method eliminates the need for wet cleaning of individual chips after dicing, improving yield while avoiding the use of large amounts of organic solvents and reducing environmental harm. Attached Figure Description
[0022] Figure 1 This is a flowchart of the present invention.
[0023] Figure 2 This is a diagram of the infrared thermal imaging MEMS wafer cutting and protection structure of the present invention.
[0024] Figure 3 This is a schematic diagram illustrating the working principle of the present invention. Implementation
[0025] The technical solution of the present invention will be further described below with reference to specific embodiments.
[0026] The technical problem solved by this invention is to provide a method for protecting infrared thermal imaging MEMS wafers during dicing, overcoming the technical problem that particles are easily introduced during the dicing of infrared thermal imaging MEMS wafers in existing technologies, which in turn affect the packaging yield.
[0027] like Figure 1 As shown, a specific embodiment of the present invention provides a method for protecting infrared thermal imaging MEMS wafers during dicing, comprising the following steps:
[0028] Constructing the MEMS structure: The infrared thermal imaging MEMS wafer includes a silicon substrate, an infrared readout circuit disposed on the silicon substrate, and a MEMS structure constructed on top of the infrared readout circuit.
[0029] Detailed Implementation: The infrared thermal imaging MEMS wafer includes a silicon substrate, an infrared readout circuit disposed on the silicon substrate, and a MEMS structure built on top of the infrared readout circuit. In specific implementation, the infrared readout circuit is fabricated on the silicon substrate using CMOS process technology. The next step is to integrate it using MEMS process technology, constructing the MEMS structure through thin film, photolithography, and etching cycle processes. The side of the silicon substrate wafer with the MEMS structure is called the crystal face, and the other side is called the crystal back.
[0030] Photoresist coating: Photoresist is coated on the surface of the MEMS structure on the silicon-based wafer.
[0031] Specific implementation method: Photoresist is coated on the surface of the MEMS structure on the silicon-based wafer, that is, photoresist is coated on the crystal surface of the infrared thermal imaging MEMS wafer to form a photoresist layer. In a specific embodiment, the photoresist is coated on the crystal surface of the infrared thermal imaging MEMS wafer by spin coating. The photoresist is applied to the crystal surface of the infrared thermal imaging MEMS wafer using an automated coating equipment that integrates spin coating and baking. The thickness of the photoresist is 1 micrometer to 2 micrometers.
[0032] Modifying the photoresist surface to a hydrophobic state: A silicon-based or fluorine-based hydrophobic electronic solution is coated on the photoresist surface to form a coating. The silicon-based or fluorine-based hydrophobic electronic solution modifies the photoresist surface to a hydrophobic state, so that the contact angle between the modified photoresist surface and the crystal plane is greater than 100 degrees.
[0033] Specific implementation method: A fluorine-based hydrophobic electron solution is coated onto the photoresist surface, namely: First, the parameters of the manual coating machine are set; second, the wafer is placed on a vacuum chuck, and the fluorine-based electron solution is distributed onto the wafer surface using a graduated dropper; third, the electron solution is spin-coated using the coating machine; fourth, the process is allowed to stand at room temperature for several hours. After the process is implemented, as shown... Figure 3 As shown, the contact angle of the crystal surface is greater than 90 degrees, indicating a hydrophobic state. The contact angle refers to the angle between the solid-liquid interface, through the liquid interior, and at the gas-liquid interface at the solid-liquid-gas three-phase junction. If the contact angle is greater than 90 degrees, the solid surface is hydrophobic, meaning the liquid does not easily wet the solid and easily moves on the surface. Because the surface energy of the fluorine-containing groups in the fluorine-containing coating decreases with the substitution of fluorine atoms, the nano-coating surface has ultra-low surface energy. Therefore, after the photoresist surface is modified with fluorine-based electronic reagents, the contact angle is greater than 90 degrees, achieving a lotus leaf effect. Dust does not easily adhere, so particles generated during the dicing process are easily washed away by water.
[0034] Cutting: The infrared thermal imaging MEMS wafer is cut.
[0035] In a specific embodiment: a silicon-based or fluorine-based hydrophobic electron solution is applied to the photoresist surface by spin coating or spraying, forming a nano-coating on the photoresist surface. The silicon-based or fluorine-based hydrophobic electron solution modifies the photoresist surface to a hydrophobic state, resulting in a contact angle greater than 100 degrees between the modified photoresist surface and the crystal plane. The wafer surface is protected by photoresist and is hydrophobic, making it extremely easy for particles introduced during wafer cutting to be washed away by cooling water, effectively curbing particle contamination on the wafer surface. Simultaneously, the introduced protective layer does not alter the material properties of the MEMS structure itself, and the protective layer is removed together with the dry release step of the infrared chip sacrificial layer. In a specific embodiment, the silicon-based or fluorine-based hydrophobic electron solution is applied to the photoresist surface by spin coating or spraying. The silicon-based or fluorine-based hydrophobic electron solution forms a nano-coating on the photoresist surface, with a thickness of 10 nm to 100 nm. The contact angle between the modified photoresist surface and the crystal plane is 100 to 125 degrees.
[0036] like Figure 2 As shown, a specific embodiment of the present invention is as follows: An infrared thermal imaging MEMS wafer dicing protection structure is constructed, comprising a silicon substrate 1, an infrared readout circuit 2 disposed on the silicon substrate, a MEMS structure 3 integrated on the infrared readout circuit 2, a photoresist layer 4 disposed on the MEMS structure 3, and a chemical coating 5 coated on the photoresist layer 4. The MEMS structure 3 is constructed on top of the infrared readout circuit 2 of the silicon substrate wafer to form a crystal plane. Photoresist is coated on the upper surface of the MEMS structure 3 to form a photoresist layer 4. A silicon-based or fluorine-based hydrophobic electronic chemical is coated on the photoresist surface, forming a coating on the photoresist surface. The silicon-based or fluorine-based hydrophobic electronic chemical modifies the photoresist surface to a hydrophobic state, such that the contact angle between the modified photoresist surface and the crystal plane is greater than 100 degrees. The thickness of the nano-coating formed by the silicon-based or fluorine-based hydrophobic electronic chemical is 10 nm to 100 nm. The silicon-based or fluorine-based hydrophobic electronic chemical forms a nano-coating on the photoresist surface.
[0037] The technical effect of this invention is to provide a method and structure for protecting infrared thermal imaging MEMS wafers during dicing, comprising the following steps: the infrared thermal imaging MEMS wafer includes a silicon-based infrared readout circuit and a MEMS structure integrated on the circuit; a MEMS structure is constructed on one side of the silicon-based wafer to form a crystal plane; photoresist is coated on the crystal plane of the silicon-based wafer; a silicon-based or fluorine-based hydrophobic electronic solution is applied to the surface of the photoresist to form a coating; the silicon-based or fluorine-based hydrophobic electronic solution modifies the surface of the photoresist to a hydrophobic state, such that the contact angle between the modified photoresist surface and the crystal plane is greater than 100 degrees; and the infrared thermal imaging MEMS wafer is diced. This invention discloses a method and structure for protecting infrared thermal imaging MEMS wafers during dicing. The wafer surface is protected by photoresist and is hydrophobic. Particles introduced during wafer dicing are easily washed away by cooling water, effectively preventing particle contamination on the wafer surface. Furthermore, the introduced protective layer does not alter the material properties of the MEMS structure itself. The protective layer is removed along with the dry release step of the infrared chip sacrificial layer. Compared to existing technologies, this method eliminates the need for wet cleaning of individual chips after dicing, improving yield while avoiding the use of large amounts of organic solvents and reducing environmental harm.
[0038] The above description, in conjunction with specific preferred embodiments, provides a further detailed explanation of the present invention. It should not be construed that the specific implementation of the present invention is limited to these descriptions. For those skilled in the art, various simple deductions or substitutions can be made without departing from the concept of the present invention, and all such modifications and substitutions should be considered within the scope of protection of the present invention.
Claims
1. A method for protecting infrared thermal imaging MEMS wafers during dicing, characterized in that, Includes the following steps: Constructing a MEMS structure: The infrared thermal imaging MEMS wafer includes a silicon substrate and an infrared readout circuit disposed on the silicon substrate. A MEMS structure is constructed on the infrared readout circuit to form a crystal plane. Photoresist coating: Photoresist is coated onto the surface of the MEMS structure; Modifying the photoresist surface to a hydrophobic state: Coating the photoresist surface with a silicon-based or fluorine-based hydrophobic electronic solution to form a coating on the photoresist surface. The silicon-based or fluorine-based hydrophobic electronic solution modifies the photoresist surface to a hydrophobic state, so that the contact angle between the modified photoresist surface and the crystal plane is greater than 100 degrees. Cutting: The infrared thermal imaging MEMS wafer is cut; The photoresist and the coating on the surface of the photoresist layer are removed together in the dry release step of the sacrificial layer of the infrared thermal imaging MEMS wafer.
2. The infrared thermal imaging MEMS wafer dicing protection method according to claim 1, characterized in that, The silicon-based or fluorine-based hydrophobic electronic solution is applied to the photoresist surface by spin coating or spray coating.
3. The infrared thermal imaging MEMS wafer dicing protection method according to claim 1, characterized in that, The silicon-based or fluorine-based hydrophobic electronic solution forms a nano-coating on the photoresist surface.
4. The infrared thermal imaging MEMS wafer dicing protection method according to claim 1, characterized in that, The thickness of the nano-coating formed by the silicon-based or fluorine-based hydrophobic electronic liquid is 10 nm to 100 nm.
5. The infrared thermal imaging MEMS wafer dicing protection method according to claim 1, characterized in that, The contact angle between the modified photoresist surface and the crystal plane is 100 to 125 degrees.
6. The infrared thermal imaging MEMS wafer dicing protection method according to claim 1, characterized in that, The photoresist is applied to the crystal surface of the infrared thermal imaging MEMS wafer by spin coating or spray coating.
7. The infrared thermal imaging MEMS wafer dicing protection method according to claim 1, characterized in that, The photoresist has a thickness of 1 to 2 micrometers.
8. A protective structure for infrared thermal imaging MEMS wafer dicing, characterized in that, The process includes a silicon substrate, an infrared readout circuit disposed on the silicon substrate, a MEMS structure integrated on the infrared readout circuit, a photoresist layer disposed on the MEMS structure, and a chemical coating applied to the photoresist layer. The MEMS structure is constructed on top of the infrared readout circuit on the silicon substrate wafer to form a crystal plane. Photoresist is coated on the upper surface of the MEMS structure to form a photoresist layer. A silicon-based or fluorine-based hydrophobic electronic chemical is applied to the photoresist surface to form a coating. The silicon-based or fluorine-based hydrophobic electronic chemical modifies the photoresist surface to a hydrophobic state, making the contact angle between the modified photoresist surface and the crystal plane greater than 100 degrees. The infrared thermal imaging MEMS wafer is then diced. The photoresist and the coating on the photoresist layer surface are removed together in the dry release step of the infrared thermal imaging MEMS wafer sacrificial layer.
9. The infrared thermal imaging MEMS wafer dicing protection structure according to claim 8, characterized in that, The thickness of the nano-coating formed by the silicon-based or fluorine-based hydrophobic electronic liquid is 10 nm to 100 nm.
10. The infrared thermal imaging MEMS wafer dicing protection structure according to claim 8, characterized in that, The silicon-based or fluorine-based hydrophobic electronic solution forms a nano-coating on the photoresist surface.