An exhaust system and device and method for preventing backflow of dust particles

Abstract

The invention provides an exhaust system and an apparatus for preventing dust backflow and a method thereof. Through real-time monitoring on a motor rotating speed signal of a vacuum pump and gas pressures of an upstream and a downstream of a filter, when the measured motor rotating speed equals to or lower than a set first rotating speed, a difference value of the measured pressures of the upstream and the downstream can reach a threshold set by current processes, and a control valve is closed before the motor rotating speed is decreased the second rotating speed. According to the invention,an exhaust pipeline communicated with a reaction chamber is closed before the motor rotating speed of the vacuum pump is reduced or rotation stops due to fault, dust backflow is blocked, and loss of core hardware in the reaction chamber due to pollution is effectively avoided.

Description

technical field [0001] The present invention relates to a semiconductor device with a vacuum reaction chamber, in particular to an exhaust system suitable for the above-mentioned semiconductor device and a device and method for preventing backflow of dust particles. Background technique [0002] The existing MOCVD (Metal Organic Chemical Vapor Deposition) equipment includes a reaction chamber. Through the shower head set on the top of the reaction chamber, the MO source and process gas are respectively introduced into the shower head for mixing and then injected into the reaction chamber to act on the reaction chamber. On a rotatable heating base in the chamber, epitaxial thin film is grown on the substrate placed on the heating base. [0003] On the exhaust pipeline connected with the gas outlet of the reaction chamber, a shut-off valve, a filter, a vacuum pump, and a waste gas processor are arranged in sequence. During the normal process, the gas inside the reaction chamb...

AI Technical Summary

Problems solved by technology

However, in some special cases, for example, when the pump body of the vacuum pump fails, the shut-off valve has not been closed, and the speed of the motor in the pump has begun to drop, which will cause the pressure downstream of the filter to rise; when the downstream pressure is greater than the chamber of the reaction chamber When the internal pressure is high, a large amount of dust particles and impurities accumulated on the filter between the chamber and the pump body will quickly flow back into the reaction chamber, causing serious pollution in the chamber, and even blocking the spray hole of the sprinkler head

[0004] For example, due to the leakage of cooling water in the vacuum pump, the purge gas N 2 Due to lack of other reasons, the above-mentioned problem of dust particle backflow may occur when the pump body is shut down due to overheating failure; among them, the control of the purge gas N 2 The delay mechanism when shutting down will further accelerate the return flow and expand the adverse effects

Or, due to the particles of the reaction product falling into the pump body, its power consumption suddenly increases, which may also cause a sudden overload fault; when overloaded, the operating frequency of the vacuum pump inverter will be automatically adjusted to prevent component damage

For example, in a specific example, the overload compensation of the vacuum pump starts from the frequency of 100Hz. When the frequency is reduced to around 40Hz, the motor speed of the pump body decreases correspondingly with the frequency reduction. At this time, if the upstream and downstream pressures are detected, it can be known that backflow has occurred; but , based on the current control mechanism, the control system of the vacuum pump delayed more than 5s before sending out an alarm, during which the frequency was further reduced to 2.5Hz, but no software control or hardware linkage operation was performed; The corresponding control command is issued to close the shut-off valve, etc.

That is, the delay in sending the alarm to indicate that the frequency dropped to 40 Hz continued to drop below 10 Hz during the delay, causing dust particles to flow back into the reaction chamber

It takes at least two weeks to clean the contaminated reaction chamber and replace parts such as spray heads, which leads to long-term production stoppage and huge economic losses

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