With the rapid development of information technology, various industries have higher and higher requirements for chips, such as high speed, nanoscale ultra-small size, low power consumption, low delay, etc., and these requirements have put forward higher requirements for the performance and accuracy of microelectronics manufacturing equipment.
Process of Microelectronics Manufacturing Equipment
The process of microelectronics manufacturing is very complicated, starting with raw materials, and going through many complicated steps to get the final chip that can be used. The general process is as follows:
1.Addition Process
1.1 Doping (diffusion, ion implantation)
Corresponding equipment: diffusion furnace, ion implantation machine, annealing furnace.
1.2 Thin films (oxidation, chemical vapor deposition, sputtering, epitaxy)
Corresponding equipment: oxidation furnace, CVD reactor, sputtering coating machine, epitaxial equipment.
2.Subtraction Process
Etching (wet etching, dry etching)
Corresponding equipment: wet etching machine, reactive ion etching machine.
3.Auxiliary Process
Polishing and cleaning (chemical mechanical flattening, cleaning)
Corresponding equipment: CMP polishing machine, silicon wafer cleaning machine.
4.Graphic Transfer Process
Graphic Transfer (Lithography)
5.Subsequent Process
Testing and Encapsulation (Testing, encapsulation)
Corresponding equipment: test equipment, scribing machine, bonding machine
Lithography machine is also called mask alignment exposure machine, exposure system, lithography system, etc. The lithography process is generally divided into 8 basic steps: air coating film, rotary coating, soft drying, alignment and exposure, post-exposure baking, developing, solid film baking, developing check. Alignment and exposure are performed in the Lithography Tool. Other processes are carried out on the glue-coated developer (Track).
There are two important working platforms in the alignment and exposure process of the lithography machine. One is the workpiece platform, which is used to carry the silicon wafers, namely the wafers. The other is the mask stage, which is used to carry the mask plate, or mask for short. The mask carries the design pattern, and the light shining through the mask onto the wafer will project the design pattern on the mask onto the wafer's photoresist. The light source should be screened through multiple mirrors for the final spectrum, through the mask, and then through the projection objective, which has multiple lenses, including moving mirrors, in order to adjust the aberration.
Note: Image source network
Application of Piezo Nano Motion Products in Lithography Machine
As the size of integrated circuits becomes smaller and smaller, the aberrations of lithographic projection objective have more and more influence on the image quality. However, the aberrations such as astigmatism, spherical aberration and distortion can be compensated in real time by using piezo nano motion products as the driving source of the objective lens.
I)CoreMorrow N31 Linear Piezo Motor is Used for High Precision Fine-tuning of the Projection Objective
The flexible hinge type piezo nano positioning platform produced by the CoreMorrow has the precision up to nanometer or even sub-nanometer level, and the upper limit of displacement can be up to about 1mm.
The linear piezo motor produced by CoreMorrow can not only meet the travel requirements of up to 100mm, but also ensure the corresponding nano-level positioning accuracy, such as CoreMorrow N31 linear piezo motor, can ensure a large range, but also provide high-precision motion regulation.
Step Drive is adopted to ensure large stroke, nanometer precision and large output
CoreMorrow N31 linear piezo motor is similar of the walking way of stepping movement, its interior has more groups of piezo actuators, each step is performed by two pairs of piezo actuators, and each piezo actuators controlled by voltage signa. The elongation and contraction between each pair of piezo actuator movement coordination control the middle shift lever forward or backward.
Incremental Encoder Ensures High Precision Position Control
N31 linear piezo motor has non-contact optical encoder built-in, high resolution, simple structure, small volume, for the piezo motor movement platform to provide a high precision movement, and not affected by mechanical action, elastic deformation and so on.
Note: Image source network
II)CoreMorrow Piezo Hexapod Parallel Mechanism is used in a Lithography Machine to Adjust the Tilt and Position of the Wafer or Objective Lens
CoreMorrow Piezo Hexapod is different from the common six-axis parallel mechanism, its linear resolution can be better than 0.5 nm, and deflection angle motion resolution can be better than 0.5μrad. This provides ultra-high positioning accuracy for six-axis alignment and angle adjustment of the wafer or objective lens in the lithography machine, and can be used to eliminate the thermal distortion of the objective lens caused by laser energy and compensate the image quality.
The six driving rods of CoreMorrow H60 Hexapod parallel mechanism are all piezo driving. The six piezo actuators are connected in parallel, and the actuators cooperate with each other to control the tilt or linear movement of the moving surface of the upper end. This kind of structure has no error accumulation, small error and high precision.
H60 Hexapod parallel mechanism platform is controlled by the upper computer software, and provides VC++, Matlab, LabView routines.
III)CoreMorrow Piezo Actuator is used for Mask Alignment and Positioning Fine Adjustment
The workpiece table and mask table are mainly composed of three parts: mechanical structure, measurement and control. A closed loop is formed between the workpiece table, mask table, transmission structure and position sensor to complete the accurate alignment between the workpiece table and mask table. This process requires that the motion of the mask table and the workpiece table must keep accurate alignment, otherwise it will lead to the offset of the imaging position, which will affect the accuracy of the final set engraving.
Therefore, the projection objective with four times reduction magnification is generally adopted, which can significantly reduce the impact of mask defects on image quality. But at the same time, the motion speed of the mask table is required to be 4 times faster than that of the workpiece table. This requires the moving machinery part to have the characteristics of high speed and high precision.
The CoreMorrow linear piezo actuator has the characteristics of small size, fast response speed, high precision, large output and so on, which can meet the requirements of high speed and high precision in mask alignment.
For example, CoreMorrow VS12 series piezo actuator’s stroke range is 9 to 152μm, output up to 1200N, fixed end and mobile end are connected by mechanical interface (flat head, internal thread, external thread, ball head, custom, etc.). It adopts piezo ceramic direct drive structure, with millisecond level fast response ability. Fast and high precision mask alignment can be achieved through the coordination of multiple piezo actuators.
In the process of exposure, due to the movement of the mask table, there will also be a large inertia force, which will cause the sliding of the mask table, leading to the reduction of accuracy. In order to compensate the uncontrollable vibration or position deviation, it is also necessary to adjust the moving machinery part with high speed and high precision, and coordinate with the position sensor.
IV)CoreMorrow Piezo Actuators are used for Inertia Cancellation and Active Vibration Suppression
Due to the high adjustment speed of the workpiece table and mask table in the lithography machine, inertia will be generated, which will cause the vibration of the table, and has an adverse effect on lithography.
The output of CoreMorrow piezo actuator can be up to 50kN, and the response speed can be up to millisecond level, which can quickly and accurately offset the vibration of the table.
V)CoreMorrow Capacitance Sensor is used in Lithography Machines for Position or Vibration Detection
The deviation or vibration of the workpiece table, mask table and objective lens in the lithography machine need to be detected by the sensor, and the capacitance sensor has been widely used in the lithography machine because of its simple structure, high precision and small volume.
CoreMorrow capacitance sensor is now on sale, with a variety of ranges, after the actual test, the resolution can be up to 1.25nm, -3db bandwidth up to 2kHz, linearity up to 0.05%, repetition up to 0.0025%.
CoreMorrow capacitance sensor is based on an ideal parallel plate capacitor principle, the sensor and the opposite surface of the measured target to form two electrodes. The principle of protective ring capacitor ensures that the sensor is still linear when measuring any metal.
CoreMorrow capacitance sensor is equipped with a signal acquisition module, which converts the capacitance value between the capacitance sensor and the measured surface into a voltage value through an internal circuit. The output voltage range is 0~10V, and the output range is linear with the capacitance sensor from 0 to the maximum range.
The capacitance sensor is very suitable for vibration detection of table, mask table and objective lens. It has three ranges of 100μm, 200μm and 500μm, and its static detection resolution is 1.25nm, 2.5nm and 5nm, respectively. Its outer diameter is only φ10mm, and the small size is easy to integrate.
Conclusion
Piezo nanomotion products are used in ultra-high precision instruments such as lithography machines, because of its rapid response and high precision. In addition to the above applications, there are many piezo nanomotion products can be applied to lithography machines, such as piezo phase shifter for moving mirror phase shift, piezo tip/tilt stage for moving mirror phase shift and leveling, two-dimensional piezo stages for eccentric alignment of the objective lens, piezo ceramics for sensing and actuators... And so on, this is related to the specific structure of the lithography machine and the optical components adopted.
In addition, CoreMorrow can also customize large load bearing, large hole six-axis piezo nano positioning stage, used for objective position adjustment and tilt adjustment; The integrated system of piezo nano positioning stage and vibration detection capacitor sensor can also be customized to integrate detection and vibration reduction motion.
CoreMorrow has been dedicated to piezo nano motion and control technology for 15 years, providing customers with countless solutions.
Welcome to contact us for any high precision position adjustment programs, we will provide specific high adaptability solutions according to your application.