| Patent application number | Description | Published |
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| 20100024716 | METHOD AND APPARATUS FOR CONTROLLING DIAMETER OF A SILICON CRYSTAL INGOT IN A GROWTH PROCESS - An improvement to a method and an apparatus for growing a monocrystalline silicon ingot from silicon melt according to the CZ process. The improvement performs defining an error between a target taper of a meniscus and a measured taper, and translating the taper error into a feedback adjustment to a pull-speed of the silicon ingot. The conventional control model for controlling the CZ process relies on linear control (PID) controlling a non-linear system of quadratic relationship defined in the time domain between the diameter and the pull-speed. The present invention transforms the quadratic relationship in the time domain between the diameter and the pull-speed into a simile, linear relationship in the length domain between a meniscus taper of the ingot and the pull-speed. The present invention applies a linear control (modified PID) which operates in the length domain, and controls a system that has a linear relationship between the ingot taper and the pull-speed in the length domain to control the diameter of a growing silicon ingot. | 02-04-2010 |
| 20100024718 | Procedure for in-situ determination of thermal gradients at the crystal growth front - A method and apparatus for growing a semiconductor crystal include pulling the semiconductor crystal from melt at a pull speed and modulating the pull speed by combining a periodic pull speed with an average speed. The modulation of the pull speed allows in-situ determination of characteristic temperature gradients in the melt and in the crystal during crystal formation. The temperature gradients may be used to control relevant process parameters that affect morphological stability or intrinsic material properties in the finished crystal such as for instance the target pull speed of the crystal or the melt gap, which determines the thermal gradient in the crystal during growth. | 02-04-2010 |
| 20100206219 | METHOD AND APPARATUS FOR CONTROLLING DIAMETER OF A SILICON CRYSTAL INGOT IN A GROWTH PROCESS - An improvement to a method and an apparatus for growing a monocrystalline silicon ingot from silicon melt according to the CZ process. The improvement performs defining an error between a target taper of a meniscus and a measured taper, and translating the taper error into a feedback adjustment to a pull-speed of the silicon ingot. The conventional control model for controlling the CZ process relies on linear control (PID) controlling a non-linear system of quadratic relationship defined in the time domain between the diameter and the pull-speed. The present invention transforms the quadratic relationship in the time domain between the diameter and the pull-speed into a simile, linear relationship in the length domain between a meniscus taper of the ingot and the pull-speed. The present invention applies a linear control (modified PID) which operates in the length domain, and controls a system that has a linear relationship between the ingot taper and the pull-speed in the length domain to control the diameter of a growing silicon ingot. | 08-19-2010 |
| 20100319611 | Method and apparatus for controlling the growth process of a monocrystalline silicon ingot - The present invention provides a method and apparatus for controlling the growth of a silicon ingot in which the diameter of the growing silicon ingot can be accurately measured. A camera captures an image of the interface ring between the growing silicon ingot and the silicon melt. An image processor extracts local intensity maxima from the captured image, which are then digitized into an image data which comprises attributes of the pixels forming the local intensity maxima. An analyzer statistically analyzes the image data to derive parameters of an equation statistically simulating the interface ring. A probabilistic filter conducts the statistical analysis on the equation in which the respective pixels are weighted by their weight factors. The weight factor functions to attenuate the effect of noises caused by pixels which do not represent the interface ring. The statistical analysis may be repeated, using the renewed parameters, to progressively attenuate the effect of the noises to thereby obtain a satisfactorily accurate diameter of the silicon ingot. | 12-23-2010 |
| 20110060467 | METHOD FOR CORRECTING SPEED DEVIATIONS BETWEEN ACTUAL AND NOMINAL PULL SPEED DURING CRYSTAL GROWTH - A system and method correct crystal pulling motor speed deviations in a crystal pulling mechanism. In a first embodiment, a processor implements a tracking filter by estimating new filter state based on previous state and the since-then-travelled nominal distance, and then updating the filter state based on estimation error and filter gains which are also functions of the travelled nominal distance. In a second embodiment, a harmonic tracking filter suppresses residual harmonic modulation and allows a short time constant. Rapid variations of pulling speed may thus be corrected. | 03-10-2011 |
| Patent application number | Description | Published |
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| 20090064923 | SILICON SINGLE CRYSTAL PULLING METHOD - An object of the present invention is to provide a silicon single crystal pulling method of accurately controlling the diameter of a silicon single crystal, thereby obtaining a high-quality silicon single crystal with little crystal defect. | 03-12-2009 |
| 20100175611 | METHOD FOR MANUFACTURING SILICON SINGLE CRYSTAL - In this method for manufacturing a silicon single crystal, when growing the silicon single crystal, in order to control the V/G value with high accuracy so as to yield a desired defect-free region, it is important to conduct the pulling at a constant pulling rate. In the method for pulling a silicon single crystal in the present invention, in order to control the V/G value with high accuracy, the distance Δt between the melt surface of the silicon melt and the heat shielding member that is disposed so as to oppose to and to partially cover this melt surface is continuously measured while pulling (growing) the silicon single crystal. | 07-15-2010 |
| 20100319612 | METHOD OF PRODUCING SILICON SINGLE CRYSTAL - In a method of producing a silicon single crystal through a Czochralski method, the pulling process includes a process of conducting a neck trial pulling for the formation of a neck portion after a seed crystal is dipped into a melt and before a neck actual pulling for the formation of a neck portion is conducted, and it is judged whether or not a temperature of the melt is a temperature suitable for the formation of the neck portion from a change of a diameter in the neck portion formed by the neck trial pulling. | 12-23-2010 |
