Micron-scale photolithography machine for advanced packaging and applications

Abstract

The application relates to a micron-level photoetching machine for advanced packaging and application and belongs to the field of exposure technology. The micron-level photoetching machine for advanced packaging comprises a motion control platform and a gantry installed on a marble base, a suction device installed on the motion control platform, a fine alignment system and a coarse alignment system of the gantry and an optical path system. The micron-level photoetching machine is provided with a combination of the coarse alignment system and the fine alignment system, can achieve higher micron-level alignment precision although the alignment time is lengthened, can ensure that an accurate focal plane is obtained through real-time focusing alignment by using a displacement sensor, and can provide good effects for subsequent exposure. The micron-level photoetching machine can simultaneously expose wafers of two stations, effectively improves the production capacity efficiency, and further reduces the error of manual adjustment by using a piezoelectric screw to adjust the flatness and inclination of a DMD.

Description

Technical Field

[0001] This invention relates to a micron-level lithography machine and its application for advanced packaging, belonging to the field of exposure technology. Background Technology

[0002] LDI (Laser Direct Imaging) is a device that uses laser scanning to directly image a substrate. With the development of LDI technology, it has been increasingly applied in advanced packaging fields, such as flip-chip packaging, redistribution layers, wafer-level packaging, and 2.5D and 3D packaging. Advanced packaging technologies require high alignment accuracy, resolution precision, and high throughput. Furthermore, in the exposure process, there are situations where the pattern to be exposed is known, but the alignment information and layout of the pattern are uncertain.

[0003] Current LDI equipment still has the following problems in meeting the above requirements:

[0004] In terms of alignment accuracy, the existing LDI alignment in the circuit field is basically around ±10μm. Since the mark points of PCB circuits are relatively large (around 2mm), the alignment structure usually chosen is a combination of mechanical alignment axis and low magnification lens. This combination is difficult to identify micron-level mark points and the alignment accuracy does not meet the requirements of advanced packaging fields.

[0005] In terms of focusing, when exposing fine line widths and spacings and high-precision alignment, high-magnification telecentric lenses and low-magnification exposure lenses are usually selected. These two types of lenses have a small depth of focus (only a few micrometers). When the flatness of the adsorption platform exceeds the depth of focus, it may cause defocusing during alignment and exposure.

[0006] In terms of capacity, current LDI equipment can only expose single wafers for lithography, which is very inefficient when exposing small linewidths.

[0007] Currently, there is no LDI device that can uniformly solve the above problems. Summary of the Invention

[0008] To address the aforementioned issues, this invention provides a micron-level lithography machine for advanced packaging, comprising a motion control platform and a gantry mounted on a marble base, an adsorption device mounted on the motion control platform, a fine alignment system, a coarse alignment system, and an optical path system mounted on the gantry.

[0009] The motion control platform includes X-axis, Y-axis and Z-axis motion components, which enable the adsorption device to move in the X-axis, Y-axis and Z-axis directions;

[0010] The precision alignment system includes an alignment camera, a high-magnification telecentric lens, and a point light source;

[0011] The illumination system is an important component of the exposure engine in laser direct imaging equipment, used to achieve pattern transfer. In the illumination system, several key indicators of the exposure engine, such as wavelength, energy, uniformity, and divergence angle, directly affect the exposure effect and lithography production efficiency.

[0012] The coarse alignment system includes an alignment camera, a telecentric lens, and a point light source. The alignment camera is a large-area array camera.

[0013] In one embodiment of the present invention, the precision alignment system and / or optical path system further includes a displacement sensor for real-time detection of depth of focus.

[0014] In one embodiment of the present invention, the adsorption device includes a suction cup body, a suction cup pad, a calibration ruler assembly, and a suction cup camera. The suction cup camera and the calibration ruler assembly are disposed on the edge of the suction cup pad and are used to calibrate the positions of the alignment cameras of the fine alignment system and the coarse alignment system, and to adjust the angle between the camera and the magnification of the exposure lens.

[0015] In one embodiment of the present invention, the suction cup body is made of marble, and the suction cup pad has two stations capable of simultaneously adsorbing two wafers, as well as adsorbing photomasks. The suction cup pad is made of porous ceramic, ensuring that the wafer or photomask can be adsorbed in any area of ​​the suction cup. The adsorption body has positioning pins for the wafer and photomask, ensuring that the wafer and photomask are correctly placed on the suction cup pad. The suction cup pad also has grooves for the robotic arm to pick up and place wafers, thus enabling both automatic and manual placement.

[0016] In one embodiment of the present invention, multiple sets of optical path systems and precision alignment systems are installed on the gantry to enable simultaneous exposure of two workstations, and each set of precision alignment systems is coaxial with one set of optical path systems.

[0017] In one embodiment of the present invention, the optical path system includes an illumination system, an objective lens, a DMD, and a DMD adjustment device. The DMD adjustment device, while supporting the DMD, can adjust the flatness and tilt of the DMD. The structure of the DMD adjustment device is roughly the same as that of CN215729279U, except that the present invention uses an automatically adjustable piezoelectric screw instead of the manually adjustable differential adjustment screw of CN215729279U, thus reducing the error caused by manual adjustment.

[0018] The present invention also provides a method for exposing a wafer or mask with known exposure patterns, alignment information, and layout using the aforementioned micron-scale lithography machine, the method comprising:

[0019] Step 1: Accurately place the wafer or mask on the work station of the adsorption device, then turn on the vacuum to completely adsorb the wafer or mask;

[0020] Step 2: The wafer or mask is carried by the adsorption device of the motion control platform and moved to the bottom of the precision alignment system. Multiple mark points on the wafer or mask are selected and marked. The displacement sensor of the precision alignment system detects the position feedback signal of the wafer or mask in real time and sends it to the platform control system. The position of the focal plane is kept unchanged by the movement of the Z-axis motion component of the motion control platform, thereby achieving real-time focusing and alignment.

[0021] Step 3: Expose the wafer or mask. After exposure, the motion control platform exits and the wafer or mask is removed.

[0022] The present invention also provides a method for exposing a wafer with a known exposure pattern but unknown alignment information and layout using the aforementioned micron-scale lithography machine, the method comprising:

[0023] Step 1: Place the wafer accurately on the work station of the adsorption device, then turn on the vacuum to completely adsorb the wafer;

[0024] Step 2: The wafer is carried by the adsorption device of the motion control platform and moved to the bottom of the coarse alignment system. The coarse alignment system takes several pictures around the center of the wafer with an area array camera. The software algorithm identifies the mark points and identifies the wafer layout. Multiple mark points are selected for alignment as needed, and a part number system is established based on the mark points.

[0025] Step 3: The wafer or mask is carried by the adsorption device of the motion control platform and moved to the bottom of the precision alignment system. Multiple mark points on the wafer are selected for marking. The position feedback signal of the wafer is detected by the displacement sensor of the precision alignment system and sent to the platform control system. The position of the focal plane is kept unchanged by the movement of the Z-axis motion component of the motion control platform, thereby achieving real-time focusing and alignment.

[0026] Step 4: Expose the wafer. After exposure is complete, the motion control platform exits and the wafer is removed.

[0027] In one embodiment of the present invention, when exposing a wafer or mask, a displacement sensor of the optical path system detects the position feedback signal of the wafer or mask and sends it to the platform control system. The Z-axis motion component of the motion control platform is then used to maintain the focal plane position, thereby achieving real-time focusing and alignment. In another embodiment of the present invention, four mark points are selected, located at four different positions on the wafer or mask, and distributed as far as possible in the corners of the wafer or mask.

[0028] It should be noted that, in this invention, the axis perpendicular to the gantry beam in the planar space of the motion control platform is defined as the Y-axis, the axis parallel to the gantry beam is defined as the X-axis, and the direction of the plumb bob is defined as the Z-axis.

[0029] Terminology Explanation:

[0030] DMD: Digital Micromirror Device, is a type of optical switch that uses rotating mirrors to open and close the optical switch. The opening and closing time is relatively long, on the order of microseconds. The process is very simple: light comes out of the optical fiber and shines on the reflector of the DMD. When the DMD is open, the light can enter the other end of the optical fiber through a symmetrical optical path. When the DMD is closed, the reflector of the DMD rotates slightly, and the light is reflected and cannot enter the other end of the symmetrical path, thus achieving the effect of turning off the optical switch.

[0031] Mark point: An alignment mark used to locate the precise position of a wafer during wafer exposure. A single wafer may have multiple marks or various types of marks.

[0032] Wafer: refers to the silicon wafer used to manufacture silicon semiconductor circuits.

[0033] EFEM: This is the front-end module of the equipment, which can automatically and accurately place the wafer onto the chuck after pre-alignment.

[0034] Piezoelectric screw: A linear piezoelectric actuator that combines manual coarse adjustment and piezoelectric fine adjustment. The manual adjustment stroke can reach 9.53mm, and the fine adjustment stroke is 16μm. During use, the large stroke in the mm range can be achieved by manual coarse adjustment, and then the displacement and accuracy in the nm range can be achieved by piezoelectric fine adjustment. It is suitable for applications with large stroke and high precision requirements.

[0035] Part Number: Production part number. Different part numbers are required for producing wafers or photomasks of different specifications. The part number consists of a series of information such as alignment information, exposure pattern, thickness of the exposed material, and exposure time of the alignment camera. At the beginning of production, all wafers or photomasks of different specifications need to be made into different part numbers and stored in the part number system. During the production process, switching between different specifications of wafers or photomasks only requires switching the part number.

[0036] The beneficial effects of this invention are:

[0037] 1. The present invention is equipped with a combination of a coarse alignment system and a fine alignment system. Although the alignment time is longer, it can achieve a high micron-level alignment accuracy.

[0038] 2. This invention utilizes a displacement sensor for real-time focusing and alignment, which ensures an accurate focal plane and provides excellent results for subsequent exposure.

[0039] 3. This invention can expose wafers at two workstations simultaneously, effectively improving production capacity efficiency.

[0040] 4. This invention utilizes piezoelectric screws to adjust the flatness and tilt of the DMD, further reducing the error of manual adjustment.

[0041] 5. The present invention is equipped with a motion control platform, which enables the wafer to move on the XYZ axis, providing convenience for operation.

[0042] 6. This invention can use a coarse alignment system to identify the layout features of unknown wafers and establish part numbers, and has wide applicability. Attached Figure Description

[0043] Figure 1 This is a schematic diagram of the overall structure in one embodiment of the present invention.

[0044] Figure 2 This is a schematic diagram of the adsorption device in one embodiment of the present invention.

[0045] Figure 3 This is a schematic diagram of the structure of a precision alignment system in one embodiment of the present invention.

[0046] Figure 4 This is a schematic diagram of the optical path system in one embodiment of the present invention.

[0047] Figure 5 This is a schematic diagram of the structure of the DMD adjustment device in one embodiment of the present invention.

[0048] Figure 6 This is a schematic diagram of the coarse alignment system in one embodiment of the present invention.

[0049] Figure 7 This is a bottom view of the optical path system and the precision alignment system at the gantry connection point in one embodiment of the present invention.

[0050] Figure 8 This is a flowchart of a method for exposing a wafer or mask in one embodiment of the present invention.

[0051] In the diagram, 1: Motion control platform, 2: Adsorption device, 3: Precision alignment system, 4: Optical path system, 5: Coarse alignment system, 6: Displacement sensor, 2.1: Air source connector, 2.2: Suction cup pad, 2.3: Suction cup body, 2.4: Wafer, 2.5: Positioning pin, 2.6: Suction cup camera, 2.7: Calibration scale assembly, 3.1: Alignment camera, 3.2: High-magnification telecentric lens, 3.3: Fixing plate, 3.4: Precision alignment point light source, 4.1: DMD, 4.2: Piezoelectric screw, 4.3: Illumination system, 4.4: Objective lens, 4.6: DMD adjustment device, 4.7: Angle rotating block, 4.8: Base, 5.1: Coarse alignment point light source, 5.2: Area array camera, 5.3: Area array camera fixing component, 5.4: Telecentric lens, 7: Gantry. Detailed Implementation

[0052] Example 1

[0053] like Figure 1 As shown, the present invention provides a micron-level lithography machine for advanced packaging, including a motion control platform 1 and a gantry 7 mounted on a marble platform, an adsorption device 2 mounted on the motion control platform 1, a fine alignment system 3 and a coarse alignment system 5 mounted on the gantry 7, and an optical path system 4.

[0054] The motion control platform 1 is a four-axis air flotation platform, including X-axis, Y-axis and Z-axis motion components, which enables the adsorption device to move in the X-axis, Y-axis and Z-axis directions.

[0055] like Figure 2 As shown, the suction cup body 2.3 of the adsorption device 2 has two workstations, each capable of simultaneously adsorbing two wafers 2.4. The suction cup body 2.3 also includes a suction cup pad 2.2, a calibration ruler assembly 2.7, a suction cup camera 2.6, positioning pins 2.5, and an air source connector 2.1. The suction cup camera 2.6 and the calibration ruler assembly 2.7 are located on the edge of the suction cup pad 2.2. The suction cup body 2.3 is a marble platform. The suction cup pad 2.2 is made of porous ceramic material, enabling the adsorption of wafers or photomasks, ensuring that the wafers or photomasks are adsorbed in any area of ​​the suction cup. The adsorption body 2.3 has positioning pins 2.5 for wafers and photomasks, allowing the wafers and photomasks to be correctly placed on the suction cup pad 2.2. The suction cup pad 2.2 has grooves for the robotic arm to pick up and place wafers, thus enabling both automatic and manual placement.

[0056] like Figure 3 As shown, the precision alignment system 3 includes an alignment camera 3.1, a high-magnification telecentric lens 3.2, and a precision alignment point light source 3.4. The displacement sensor 6 is mounted on a fixed plate 3.3, which is mounted on the crossbeam of the gantry 7.

[0057] like Figure 4As shown, the optical path system 4 includes an illumination system 4.3, an objective lens 4.4, a DMD 4.1, and a DMD adjustment device 4.6. The illumination system 4.3 is connected to the objective lens 4.4. The objective lens 4.4 passes through the crossbeam of the gantry 7 and has the DMD adjustment device 4.6 mounted on its top. The DMD adjustment device 4.6, while supporting the DMD 4.1, can adjust the flatness and tilt of the DMD 4.1 via a piezoelectric screw 4.2. The piezoelectric screw is a linear piezoelectric actuator combining manual coarse adjustment and piezoelectric fine adjustment. The manual adjustment stroke can reach 9.53 mm, and the fine adjustment stroke is 16 μm. During use, a large stroke in the mm range can be achieved through manual coarse adjustment, and then nanometer-level displacement and accuracy can be achieved through piezoelectric fine adjustment. It is suitable for applications with large strokes and high precision requirements.

[0058] like Figure 5 As shown, the DMD adjustment device 4.6 includes a DMD support platform 4.9, an angled rotating block 4.7, and a base 4.8, all of which are hollow structures to allow the light path to pass through. The base 4.8 and the DMD support platform 4.9 are connected by three piezoelectric screws 4.2 and an elastic component. The edge of the base 4.8 is also provided with two piezoelectric screws 4.2 for adjusting the rotation of the angled rotating block 4.7.

[0059] like Figure 7 As shown, four sets of optical path systems 4 and two sets of precision alignment systems 3 are installed on the crossbeam of the gantry 7. The two adjacent sets of optical path systems 4 correspond to the position of a wafer. Each pair of optical path systems 4 is equipped with a set of precision alignment systems 3 to enable simultaneous exposure of the two workstations. Each set of precision alignment systems 3 is coaxial with the optical path of one set of optical path systems 4.

[0060] like Figure 6 As shown, the coarse alignment system 5 includes an area array camera 5.2 with a coarse alignment point light source 5.1 and a telecentric lens 5.4. The area array camera 5.2 is mounted on the crossbeam of the gantry 7 by an area array camera mounting bracket 5.3. The area array camera mounting bracket is also connected to a water cooling pipe, which can cool the area array camera 5.2.

[0061] The high-magnification telecentric lens 3.2 and / or objective lens 4.4 are both equipped with displacement sensors 6.

[0062] Example 2

[0063] like Figure 8 As shown, the present invention also provides a method for exposing a wafer with known exposure patterns, alignment information, and layout using the aforementioned micron-level lithography machine, the method comprising:

[0064] Step 1: Using the EFEM system automatically or manually with the positioning pins 2.5, accurately place the two wafers 2.4 on the two stations of the adsorption device 2. Then open the air source connector 2.1 to turn on the vacuum and simultaneously and completely adsorb the two wafers 2.4.

[0065] Step 2: The wafer is carried by the adsorption device of the motion control platform and moved to the bottom of the precision alignment system 3. Four mark points on the wafer 2.4 are selected for marking to ensure that the center of the high-magnification telecentric lens 3.2 is as close as possible to the center of the displacement sensor 6. The displacement sensor 6 of the precision alignment system 3 detects the position feedback signal of the wafer or mask and sends it to the platform control system. The Z-axis motion component of the motion control platform moves to keep the focal plane position unchanged, thereby achieving real-time focusing and alignment.

[0066] Step 3: Open multiple optical path systems 4 to expose wafers 2.4 at two workstations simultaneously. After exposure is complete, motion control platform 1 exits and wafers 2.4 are removed.

[0067] Example 3

[0068] like Figure 8 As shown, the present invention also provides a method for exposing a wafer with a known exposure pattern but unknown alignment information and layout using the aforementioned micron-level lithography machine. The unknown wafer needs to have a regular arrangement of mark points, and these mark points must be present in each shot. The method includes:

[0069] Step 1: Using the EFEM system automatically or manually with the positioning pins 2.5, accurately place the two wafers 2.4 on the two stations of the adsorption device 2. Then open the air source connector 2.1 to turn on the vacuum and simultaneously and completely adsorb the two wafers 2.4.

[0070] Step 2: The wafer is carried by the motion control platform adsorption device and moved to the bottom of the coarse alignment system 5. The coarse alignment system 5 is used to take several pictures around the center of the wafer 2.4 with an area array camera. The software algorithm identifies the mark points and identifies the layout of the wafer 2.4. Four mark points are selected for alignment as needed, and a part number system is established based on the four mark points.

[0071] Step 3: The wafer or mask is carried by the adsorption device of the motion control platform and moved to the bottom of the precision alignment system 3. Four mark points on the wafer 2.4 are selected for marking to ensure that the center of the high-magnification telecentric lens 3.2 is as close as possible to the center of the displacement sensor 6. The displacement sensor 6 of the precision alignment system 3 detects the position feedback signal of the wafer and sends it to the platform control system. The Z-axis motion component of the motion control platform moves to keep the focal plane position unchanged, thereby achieving real-time focusing and alignment.

[0072] Step 4: Open multiple optical path systems 4 to expose wafers 2.4 at two workstations simultaneously. After exposure is complete, the motion control platform 1 exits and wafers 2.4 are removed.

[0073] Furthermore, before focusing and alignment, the flatness and tilt angle of DMD4.1 are automatically adjusted by piezoelectric screw 4.2. The flatness is adjusted to make DMD4.1 and the objective lens 4.4 completely horizontal, and the tilt angle is adjusted to ensure the accuracy of the tilt exposure angle.

[0074] Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Anyone skilled in the art can make various modifications and alterations without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention should be determined by the claims.

Claims

1. A micron-level lithography machine for advanced packaging, characterized in that, It includes a motion control platform and gantry mounted on a marble base, an adsorption device mounted on the motion control platform, a fine alignment system, a coarse alignment system, and an optical path system mounted on the gantry; The motion control platform includes X-axis, Y-axis and Z-axis motion components, which enable the adsorption device to move in the X-axis, Y-axis and Z-axis directions; The precision alignment system includes an alignment camera, a high-magnification telecentric lens, and a point light source; The coarse alignment system includes an alignment camera, a telecentric lens, and a point light source, wherein the alignment camera is a large-area array camera. The optical path system includes an illumination system, an objective lens, a DMD, and a DMD adjustment device. The DMD adjustment device can adjust the flatness and tilt of the DMD while supporting the DMD. The DMD adjustment device uses a piezoelectric screw that can achieve automatic adjustment instead of manual adjustment, reducing the error caused by manual adjustment. The adsorption device includes a suction cup body, a suction cup pad, a calibration ruler assembly, and a suction cup camera. The suction cup camera and the calibration ruler assembly are located on the edge of the suction cup pad and are used to calibrate the positions of the alignment cameras of the fine alignment system and the coarse alignment system, and to adjust the angle between the camera and the magnification of the exposure lens. The main body of the suction cup is made of marble. The suction cup pad has two stations that can simultaneously adsorb two wafers and also adsorb photomasks. The suction cup pad is made of porous ceramic, which can ensure that the wafer or photomask can be adsorbed in any area of ​​the suction cup. The gantry can be equipped with multiple optical path systems and precision alignment systems to enable simultaneous exposure of two workstations, and each precision alignment system is coaxial with one optical path system.

2. The micron-level lithography machine for advanced packaging according to claim 1, characterized in that, The precision alignment system and / or optical path system also includes a displacement sensor for real-time detection of depth of focus.

3. A method for exposing a wafer or mask with known alignment information and layout using the micron-level lithography machine of claim 2, characterized in that, The method includes: Step 1: Accurately place the wafer or mask on the work station of the adsorption device, then turn on the vacuum to completely adsorb the wafer or mask; Step 2: The wafer or mask is carried by the adsorption device of the motion control platform and moved to the bottom of the precision alignment system. Multiple mark points on the wafer or mask are selected and marked. The position feedback signal of the wafer or mask is detected by the displacement sensor of the precision alignment system and sent to the platform control system. The position of the focal plane is kept unchanged by the movement of the Z-axis motion component of the motion control platform, thereby achieving real-time focusing and alignment. Step 3: Expose the wafer or mask. After exposure, the motion control platform exits and the wafer or mask is removed.

4. A method for exposing a wafer with a known exposure pattern but unknown alignment information and layout using the micron-level lithography machine described in claim 2, characterized in that, The method includes: Step 1: Place the wafer accurately on the work station of the adsorption device, then turn on the vacuum to completely adsorb the wafer; Step 2: The wafer is carried by the adsorption device of the motion control platform and moved to the bottom of the coarse alignment system. The coarse alignment system takes several pictures around the center of the wafer with an area array camera. The software algorithm identifies the mark points and identifies the wafer layout. Multiple mark points are selected for alignment as needed, and a part number system is established based on the mark points. Step 3: The wafer or mask is carried by the adsorption device of the motion control platform and moved to the bottom of the precision alignment system. Multiple mark points on the wafer are selected for marking. The position feedback signal of the wafer is detected by the displacement sensor of the precision alignment system and sent to the platform control system. The position of the focal plane is kept unchanged by the movement of the Z-axis motion component of the motion control platform, thereby achieving real-time focusing and alignment. Step 4: Expose the wafer. After exposure is complete, the motion control platform exits and the wafer is removed.

5. The exposure method for a micron-scale lithography machine according to claim 3 or 4, characterized in that, When exposing a wafer or mask, the position of the wafer or mask is detected by the displacement sensor of the optical path system and the feedback signal is sent to the platform control system. The position of the focal plane is kept unchanged by the movement of the Z-axis motion component of the motion control platform, thereby achieving real-time focusing and alignment.

6. The exposure method for a micron-scale lithography machine according to claim 3 or 4, characterized in that, The number of the mark points is four, located in four different positions on the wafer or mask, and distributed as far as possible in the corners of the wafer or mask.

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