Monocrystal growth system and method capable of controlling shape of ingot interface

Patent metadata

Field	Value
Publication number	US-2017356100-A1
Application number	US-201515540219-A
Country	US
Kind code	A1
Filing date	Aug 20, 2015
Priority date	Dec 30, 2014
Publication date	Dec 14, 2017
Grant date	—

Abstract

The present invention relates a method for controlling a growth interface shape while growing a monocrystal ingot by a Czochralski method, the method including a step of starting a growth of the monocrystal ingot after setting a control condition of a monocrystal growing process so that an interface of the ingot becomes a target shape; a step of deriving a measurement value by measuring a weight of the ingot grown for a predetermined time by means of a load cell disposed on an upper portion the monocrystal ingot; a step of deriving a theoretical value of the weight of the monocrystal ingot through a diameter of the monocrystal ingot measured by a diameter measuring camera disposed outside of a process chamber for a predetermined time and a height of the monocrystal ingot grown for the predetermined time; a step of predicting a growth interface shape of a growing monocrystal ingot by deriving a difference between the measurement value and the theoretical value; and changing process conditions during growth of the monocrystal ingot by comparing the predicted interface shape of the monocrystal ingot with the targeted interface shape of the monocrystal ingot. Therefore, the interface shape of the growing ingot may be predicted during the growing process of the monocrystal ingot, and the process conditions may be controlled to grow the silicon ingot in the targeted interface shape.

First claim

1 . A monocrystal growing system as a system of controlling a growth interface shape by pulling up and growing a monocrystal ingot in a process chamber by a Czochralski method, the system comprising:
an ingot weight measuring part for measuring a weight of a growing ingot; an ingot diameter measuring part for measuring a diameter of the growing ingot; an ingot height measuring part for measuring a height of the growing ingot; a comparing part for comparing a measurement value obtained by measuring a weight increase amount of the ingot for unit time and a theoretical value of the ingot weight increase amount derived through a change in the diameter and the height of the ingot for the unit time; and a control part changing a process condition during monocrystal ingot growth according to a difference between the measurement value and the theoretical value derived from the comparing part.

2 . The monocrystal growing system of claim 1 , wherein the ingot weight measuring part measures the weight of the ingot at a specific time by a load cell connected to a wire provided on an upper portion of the process chamber and on which the monocrystal ingot is pulled.

3 . The monocrystal growing system of claim 1 , wherein the ingot diameter measuring part is provided on the upper portion of the process chamber and is measured by a camera illuminating a growth interface of the ingot.

4 . The monocrystal growing system of claim 1 , wherein the ingot height measuring part measures a length of an ingot body grown through a change in a height of a seed chuck supporting the ingot for the unit time.

5 . The monocrystal growing system of claim 4 , wherein the length of the ingot body is calculated by multiplying a current pulling speed of the ingot by the unit time.

6 . The monocrystal growing system of claim 1 , wherein the comparing part predicts a growth interface shape of the ingot to be grown by deriving the difference value between the measurement value and the theoretical value.

7 . The monocrystal growing system of claim 1 , wherein the control part changes a pulling speed of the growing ingot according to the difference between the measurement value and the theoretical value transmitted from the comparing part.

8 . The monocrystal growing system of claim 7 , wherein when the measurement value is larger than the theoretical value, it is predicted that the interface shape of the monocrystal ingot protrudes convexly downward, and the control unit increases the pulling speed of the monocrystal ingot, thereby increasing a growth speed of the monocrystal ingot.

9 . The monocrystal growing system of claim 7 , wherein when the measurement value is smaller than the theoretical value, it is predicted that the interface shape of the monocrystal ingot is formed to be concave upward, and the control unit decreases the pulling speed of the monocrystal ingot, thereby reducing a growth speed of the monocrystal ingot.

10 . A monocrystal growing method as a method for controlling a growth interface shape while growing a monocrystal ingot by a Czochralski method, the method comprising;
a step of starting a growth of the monocrystal ingot after setting a control condition of a monocrystal growing process so that an interface of the ingot becomes a target shape; a step of deriving a measurement value by measuring a weight of the ingot grown for a predetermined time by means of a load cell disposed on an upper portion the monocrystal ingot; a step of deriving a theoretical value of the weight of the monocrystal ingot through a diameter of the monocrystal ingot measured by a diameter measuring camera disposed outside of a process chamber for a predetermined time and a height of the monocrystal ingot grown for the predetermined time; a step of deriving a difference between the measurement value and the theoretical value to predict a growth interface shape of the growing monocrystal ingot; and a step of comparing the predicted interface shape of the monocrystal ingot and the targeted interface shape of the monocrystal ingot and changing process conditions during growth of the monocrystal ingot.

11 . The monocrystal growing method of claim 10 , wherein the step of starting the growth of the monocrystal ingot after setting the control condition of the monocrystal growing process so that the interface of the ingot has the target shape sets the control condition of the monocrystal growing process based on the control condition of the monocrystal ingot growing process most recently performed and a quality of the monocrystal ingot grown accordingly.

12 . The monocrystal growing method of claim 10 , wherein the step of deriving the theoretical value of the monocrystal ingot weight through the diameter of the monocrystal ingot measured by the diameter measuring camera disposed outside of the process chamber for the predetermined time and the height of the monocrystal ingot grown for the predetermined time is derived by equation 1:
Δ W =π( r/ 2) 2 ×( h 2− h 1)×( K )  Equation 1.
r diameter of the ingot measured from the diameter measuring camera h1−h2: height of the ingot changed for unit time
K: density of the ingot.

13 . The monocrystal growing method of claim 10 , wherein in the step of deriving the difference between the measurement value and the theoretical value and predicting the growth interface shape of the growing monocrystal ingot, in the case in which the measurement value is same as the theoretical value, it is predicted that the targeted interface shape of the ingot and the interface shape of the growing ingot are the same.

14 . The monocrystal growing method of claim 13 , wherein in the case in which the theoretical value is larger than the measurement value, it is predicted that the interface shape of the growing ingot is formed to be concave upward than the targeted interface shape of the ingot, and in the case in which the theoretical value is smaller than the measurement value, it is predicted that the interface shape of the growing ingot is formed to be convex downward than the targeted interface shape of the ingot.

15 . The monocrystal growing method of claim 10 , wherein in the step of comparing the predicted interface shape of the monocrystal ingot with the targeted interface shape of the monocrystal ingot and changing the process conditions during the growth of the monocrystal ingot, in the case in which the targeted interface shape of the monocrystal ingot and the predicted interface shape of the monocrystal ingot are the same, a pulling speed of the monocrystal ingot is kept the same as a current pulling speed.

16 . The monocrystal growing method of claim 10 , wherein in the step of comparing the predicted interface shape of the monocrystal ingot with the targeted interface shape of the monocrystal ingot and changing the process conditions during the growth of the monocrystal ingot, in the case in which the predicted interface shape of the monocrystal ingot is concavely recessed upward as compared with the targeted interface shape of the monocrystal ingot, a pulling speed of the monocrystal ingot is reduced so as to reduce a growth speed of the monocrystal ingot.

17 . The monocrystal growing method of claim 10 , wherein in the step of comparing the predicted interface shape of the monocrystal ingot with the targeted interface shape of the monocrystal ingot and changing the process conditions during the growth of the monocrystal ingot, in the case in which the predicted interface shape of the monocrystal ingot convexly protrudes downward as compared with the targeted interface

Assignees

• Lg Siltron Inc

Inventors

• Bang In-Sik

Classifications

• C30B29/06

  Silicon · CPC title

• C30B15/28 Primary

  using weight changes of the crystal or the melt, e.g. flotation methods · CPC title

• C30B15/26 Primary

  using television detectors; using photo or X-ray detectors · CPC title

• C30B15/20

  Controlling or regulating (controlling or regulating in general G05) · CPC title

• C30B15/22 Primary

  Stabilisation or shape controlling of the molten zone near the pulled crystal; Controlling the section of the crystal · CPC title