A Method of Origin Positioning for Controlling Wafer Lifting Movement

Abstract

An origin positioning method for controlling lifting motion of a wafer boat comprises the steps that firstly, the wafer boat is controlled to move downwards at a set speed parameter, and the wafer boat is controlled immediately to be decelerated and stopped when an origin sensor detects that the origin sensor is just shielded by a wafer boat lifting mechanism; secondly, the wafer boat is controlled to start to move upwards at a smaller speed parameter, when an origin pulse rising edge is detected, Z-phase pulses are searched for, and the wafer boat is controlled to be decelerated and stopped after the Z-phase pluses are found. In addition, after the steps, the wafer boat is continuously controlled to move downwards at a slow speed, and the wafer boat is stopped immediately when the origin pulse rising edge is detected, or Z-phase pulses are searched for, and the wafer boat is decelerated and stopped or stopped immediately after the Z-phase pulses are found. The accuracy and the stability for returning to the origin are improved through the steps. Besides, different working conditions of a digital sensor are combined for use, so that reliability is improved, and the implementation mode is quite simple.

Description

technical field [0001] The invention relates to the field of semiconductor devices and processing and manufacturing, and more specifically, relates to a method for positioning the origin of the crystal boat lifting movement for controlling the crystal boat loaded with wafers to be unloaded from the semiconductor vertical oxidation furnace equipment. Background technique [0002] The design of semiconductor devices is rapidly developing in the direction of high density and high integration, which puts forward higher and higher requirements for new technology, new technology and new equipment of semiconductor integrated circuits. Among all semiconductor special equipment, the vertical diffusion / oxidation furnace is one of the important process equipment in the pre-process of the integrated circuit production line. It is mainly suitable for diffusion, annealing, alloying, oxidation, film growth, etc. in the process of silicon wafers with a diameter of VLSL above 150mm craft. ...

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Problems solved by technology

[0010] ①. Due to the electromagnetic interference in the factory building, and NC51 is a voltage output positioning module, the module has poor anti-electromagnetic interference, which makes the stability of the control worse;

[0011] ②. The existing technology adopts a two-step positioning method, that is, only two times of positioning of the origin of the crystal boat stop, but the boat stop point and the initial origin have a large positioning error, which cannot meet the positioning accuracy of the equipment for the boat lifting mechanism. Require;

[0012] ③. In particular, the stop point of this scheme is above the origin sensor, and the boat lifting mechanism does not have a pen-and-paper home sensor. In this way, it is very inconvenient to use the home sensor for subsequent procedures, and the subsequent processing steps take the initial origin as the reference point , will continue to use the error;

[0013] ④. The error of the stop point of the wafer boat will be different each time, especially after multiple lifting processes, the wafer transfer manipulator needs to be calibrated with the wafer boat stop point, otherwise, it will be difficult to complete the accurate loading and unloading of the wafer;

[0014] ⑤. Using a single sensor type, for example, using a normally closed sensor type, when the sensor is powered off, the movement of the boat lifting mechanism cannot be controlled, so that the boat lifting mechanism falls to the negative limit and damages the crystal boat. There is a great risk in safety. Hidden danger

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