Detailed version of the silicon wafer semiconductor manufacturing process
1. POLY SILICON STACKING
First, the polysilicon and dopant are put into a quartz crucible in a monocrystalline furnace, and the temperature is raised to more than 1000 degrees Celsius to obtain the molten polysilicon.
2. INGOT GROWING
Ingot growth is a process in which polycrystalline silicon is made into monocrystalline silicon, and after the polysilicon is heated into a liquid, the thermal environment is precisely controlled to grow into high-quality monocrystal.
Related concepts:
Single crystal growth: After the temperature of the polycrystalline silicon solution is stabilized, the seed crystal is slowly lowered into the silicon melt (the seed crystal will also be melted in the silicon melt), and then the seed crystal is lifted upward at a certain speed for the crystallization process. Subsequently, the dislocations generated during the crystallization process are eliminated by necking operation. When necking to a sufficient length, the monocrystalline silicon diameter is increased to the target value by adjusting the drawing speed and temperature, and then the equal diameter is maintained to the target length. Finally, in order to prevent the dislocation and back-delay, the monocrystalline ingot is finished to obtain the finished monocrystalline ingot, which is taken out after the temperature is cooled.
Methods for preparing monocrystalline silicon: Straight-pull method (CZ method) and zone melting method (FZ method). The Straight-pull method is referred to as CZ method, which is characterized by the aggregation of a straight cylinder type thermal system, heated with graphite resistance, and the polycrystalline silicon installed in a high-purity quartz crucible is melted, and then the seed crystal is inserted into the melt surface for welding, and the seed crystal is rotated at the same time, and then the crucible is reversed, and the seed crystal is slowly lifted upward, and the monocrystalline silicon is obtained through the process of crystal introduction, amplification, shoulder turning, equal diameter growth, and finishing.
The zone melting method is a method of using polycrystalline ingots to melt and grow crystalline semiconductor crystals, using heat energy to generate a melting zone at one end of the semiconductor bar, and then welding single crystal seed crystals. The temperature is adjusted so that the molten zone slowly moves towards the other end of the rod, and through the whole bar, it grows into a single crystal with the same direction as the seed crystal. There are two types of zone melting methods: horizontal zone melting method and vertical suspension zone melting method. The former is mainly used for the purification and single crystal growth of germanium, GaAs and other materials. In the latter, a high-frequency coil is used to create a molten zone at the contact between the single crystal seed crystal and the polycrystalline silicon rod suspended above it in an atmosphere or vacuum furnace chamber, and then the molten zone is moved upward for single crystal growth.
About 85% of the wafers are produced by the Zorgial method and 15% by the zone melting method. According to the application, the monocrystalline silicon grown by the Zyopull method is mainly used for the production of integrated circuit components, while the monocrystalline silicon grown by the zone melting method is mainly used for power semiconductors. The Straight-pull process is mature, and it is easier to grow large-diameter monocrystalline silicon; The melt of the zone melting method is not in contact with the container, is not easy to pollute, and has high purity, which is suitable for the production of high-power electronic devices, but it is difficult to grow large-diameter monocrystalline silicon, which is generally only used for a diameter of 8 inches or less. In the video, it is the straight pull method.
3. INGOT GRINDING&CROPPING
Because it is difficult to control the diameter of the monocrystalline silicon rod in the process of pulling the monocrystal, in order to obtain the standard diameter of the silicon rod, such as 6 inches, 8 inches, 12 inches, etc. After pulling the single crystal, the diameter of the silicon ingot will be tumbled, and the surface of the silicon rod after tumbling is smooth, and the dimensional error is smaller.
4. WIRE SAWING
Using advanced wire cutting technology, the single crystal rod is cut into silicon wafers of appropriate thickness through slicing equipment.
5. EDGE GRINDING
Due to the small thickness of the silicon wafer, the edge of the cut silicon wafer is very sharp, and the purpose of edging is to form a smooth edge, and it is not easy to break in the future chip manufacturing.
6. LAPPING
LAPPING is when the chip is added between the heavy selected plate and the lower plate, and the pressure is applied to rotate the chip with the abrasive agent to flatten the chip.
7. ETCHING
Etching is a process that removes processing damage on the surface of a wafer by dissolving the surface layer that has been damaged by physical processing with a chemical solution.
8. DOUBLE SIDE GRINDING
Double-sided grinding is a process that flattens the wafer by removing small bumps on the surface.
9. RAPID THERMAL PROCESS
RTP is a process of rapidly heating the wafer in a few seconds, so that the defects inside the wafer are uniform, inhibit metal impurities, and prevent abnormal semiconductor operation.
10. POLISHING
Polishing is a process that ensures surface evenness through surface precision machining. The use of polishing paste and polishing cloth, with appropriate temperature, pressure and rotation speed, can eliminate the mechanical damage layer left by the previous process, and obtain a silicon wafer with excellent surface flatness.
11. CLEANING
The purpose of cleaning is to remove the residual organic matter, particles, metals, etc. on the surface of the silicon wafer after polishing, so as to ensure the cleanliness of the surface of the silicon wafer and make it meet the quality requirements of the following process.
12. INSPECTION
Flatness & resistivity tester tests the polished silicon wafers to ensure that the thickness, flatness, local flatness, curvature, warpage, resistivity, etc. of the polished silicon wafers meet customer requirements.
13. PARTICLE COUNTING
PARTICLE COUNTING is a process of accurately checking chip surfaces to determine the number of surface defects and defects through laser scattering.
14. EPI GROWING
EPI GROWING is a process of growing high quality silicon single crystal films on a ground silicon wafer by vapor chemical deposition.
Related concepts:
Epitaxial growth: refers to the growth of a single crystal layer on the single crystal substrate (substrate) that has certain requirements and is the same as the substrate crystal, as if the original crystal extends outward for a period. Epitaxial growth technology was developed in the late 1950s and early 1960s. At that time, in order to manufacture high-frequency high-power devices, it is necessary to reduce the series resistance of the collector, and require the material to withstand high voltage and high current, so it is necessary to grow a thin high-resistance epitaxial layer on the low resistance substrate. The epitaxial growth of the new single crystal layer can be different from the substrate in terms of conduction type, resistivity, etc., and can also grow multi-layer single crystals with different thicknesses and different requirements, thus greatly improving the flexibility of device design and device performance.
15. PACKING
Packaging is the packaging of the final qualified product.
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