In semiconductor manufacturing processes, lithography is one important technical link of IC pattern transfer, the gluing quality directly affects the quality of the lithography, then the coating process is particularly important. The vast majority of the photoresist in the lithography coating process is hydrophobic, while the hydroxyl groups of the silicon wafer surface and residual water molecules is hydrophilic, which resulted in poor adhesion of the photoresist and silicon wafer, in particular, it is for plastic. When developing the developer will invade the junction of the photoresist and silicon wafer, which is likely to cause drift bar, floating plastic, resulting in the failure of the lithography pattern transfer, meantime the wet etching prone to lateral corrosion. The thickening agent-HMDS (hexamethyl silazane) can improve the condition well.
Model: HMDS-6210 HMDS pretreatment system
Product Features:
1,The enclosure is made of medical grade stainless steel 316L material, the inner container is made of stainless steel 316L material; The heater is evenly distributed around the inner container outer wall, there is no electrical parts and flammable and explosive devices in the inner chamber. Toughened, bulletproof double glass door to observe the work of indoor objects at a glance.
2, The door tightness can be adjusted, the overall shape of the silicon rubber door seals to ensure the high degree of vacuum.
3,Microcomputer intelligent temperature controller, the measuring temperature is Dual Digital display, and with PID self-tuning function, accurate, reliable temperature control.
4, Intelligent touch screen control system matching Japan's Mitsubishi PLC module for users to change the procedures, temperature, vacuum degree, and each program time under different process conditions.
5,HMDS gas sealed automatically absorb and add design, good sealing performance of the vacuum chamber, to ensure that the HMDS has no gas leakage concerns.
6, The entire system uses high quality materials, no dust material, suitable for 100 grade lithography to purify the environment.
Technical parameters:
Supply Voltage: AC 380V ± 10% / 50Hz ± 2%
Input Power: 4000W
Temperature range: RT+10 ℃ -250 ℃
Temperature Resolution: 0.1 ° C
Temperature fluctuation: ± 0.5 ° C
Vacuum Degree: 133Pa
Volume: 210L
Inner size (mm): 560 * 640 *600
Overall size(mm): 720 * 820 * 1750
Shelves: 3
Unit of time: minutes
Vacuum pump: ’LEYBOLD’ DC rotary vane pump(Optional accessory), .
The necessity of HMDS pretreatment system:
In semiconductor manufacturing processes, lithography is one important technical link of IC pattern transfer, the gluing quality directly affects the quality of the lithography, then the coating process is particularly important. The vast majority of the photoresist in the lithography coating process is hydrophobic, while the hydroxyl groups of the silicon wafer surface and residual water molecules is hydrophilic, which resulted in poor adhesion of the photoresist and silicon wafer, in particular, it is for plastic. When developing the developer will invade the junction of the photoresist and silicon wafer, which is likely to cause drift bar, floating plastic, resulting in the failure of the lithography pattern transfer, meantime the wet etching prone to lateral corrosion. The thickening agent-HMDS (hexamethyl silazane) can improve the condition well. Coat the HMDS on silicon wafer surface while heated by the oven can have a reaction and generate the compounds which main component is siloxane. It successfully changes the silicon wafer surface from hydrophilic to hydrophobic, the hydrophobic group can be well combined with the photoresist which plays the role of the coupling agent.
Principle of HMDS-6000 series of pre-treatment system:
HMDS-6000 pretreatment system through the operating temperature, the processing time, to keep the processing time and other parameters of the oven HMDS,can be coated with a layer of HMDS on silicon wafer and substrate surface, and reduces the angle of contact of silicon wafers in HMDS treatment, also reduces the dosage of the photoresist and improves the adhesion of photoresist and silicon wafer.
The general workflow of HMDS-6000 Series pretreatment system:
First, confirm the operating temperature of the oven. Typical pretreatment process: Open the vacuum pump to vacuumize, when the vacuum degree of the inner chamber achieve a high vacuum degree, then start to fulfill with the nitrogen,after reach a low vacuum degree, start the process of vacuumization and nitrogen fulfilling once again.when reach the setting times of fulfilling nitrogen and remain a period of time, so that the silicon to full heat, reduce the water of the silicon wafer surface. Then start the process of vacuumization again, fill with HMDS gas, after the set time reaches, stop the HMDS liquid filled into the holding phase, start enter into the hold period, make the silicon wafer have a full reaction with HMDS. When it reaches the set hold time, start the process of vacuumization and nitrogen fulfilling once again,and complete the whole work process.The reaction mechanism of HMDS and silicon wafer shown in Figure: First, heated to 100 ℃ -200 ℃, to remove the water of the silicon wafer surface, and then HMDS with the surface OH have a reaction, and generate the silyl ether to eliminate the hydrogen bonding in silicon sheet, thus so that the polarity of the surface change into a non-polar surface. The reaction continues until the space steric hindrance (trimethylsilyl) to prevent its further reaction.
Exhaust emissions: The redundant HMDS vapor (exhaust) will be pulled out by the the vacuum pump, discharges to a dedicated exhaust collection pipes. To be done to deal specifically without the dedicated exhaust gas collection pipes.
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