JPS58172289A - Growth device of crystal - Google Patents

Abstract

PURPOSE:To detect the height of a melt surface easily and exactly and to enable the replenishing of a raw material with good controllability in a growth device for a crystal by a pulling method, by detecting the change in the atmosphere resistance between a conducting terminal installed without contacting on the melt of the raw material for the crystal and the melt. CONSTITUTION:Polycrystalline Si and a dopant are put into a crucible 1, and are melted with a heater 3 so as to prepare an Si melt 2. The bottom end of the seed crystal 4 mounted to a pulling shaft 5 is immersed in the melt 2 in the crucible 1 and is pulled gradually under rotation of the shaft 5, thereby growing a crystal 7 gradually. On the other hand, granular polycrystalline Si is replenished continuously from a raw material well 13. A DC power source 11 is turned on to apply DC bias to a conducting terminal 9 at around the time when the crystal 7 grows to a specified diameter, and the conducting electric current is amplified with a logarithmic operational amplifier 12, the output signal whereof is outputted to a display 15 for the height of the melt surface. On the other hand, the output signal of the amplifier 12 is outputted to to a solenoid coil of a mechanism for adjusting the inclination of a well 13 to adjust the rate of replenishing from the well 13 so that the height of the liquid surface is kept constant.

Description

[Detailed description of the invention] [Oa* field] This invention relates to a crystal growth apparatus using the Tararus method:
It is something to do.

[Technical background and problems with the invention]

Conventionally, the Clarus medium method has been widely used to produce single-crystal materials such as silicon. For this crystal pulling, a device is used in which polycrystalline silicon and a dopant (horizontal material) containing quartz rutz (ZFC) are heated by a heater to form a melt. Contact the IkmlK seed crystal of , and gradually pull it up while rotating the pulling axis t-1, until it reaches the lower end of the seed crystal! Lit crystal tI [This is what will be grown next.

However, in the conventional pulling device, the dopant in the I11 moat decreases exponentially as the crystal is pulled up, so the single crystal I1 with a constant O resistance value in the direction of the pulling axis is 11 There are some flaws.) Good.

In addition, it is difficult to prepare a polycrystalline silicon material for SO preparation, and it is difficult to round up the IA material when it is put into the SWC. be.

A number of proposals have already been made to recommend a rounding and crystal pulling device for raw material handling equipment to solve these problems.

However, ζOI [fare supplement 0vLir is 0IIi in Ruth I
Countermeasures against insufficient amount of liquid and measures against accidents where liquid leaks from the root l are still unresolved, and we have not yet reached the stage where animals can be put to practical use.

[Ko-01] The present invention aims to provide a method for easily and accurately detecting *a*ii* high 1, making it possible to replenish J material with good controllability, and providing nine crystal growth am. There is also c+'e.

C%@t)1! The present invention detects the height of the melt surface by installing a current-carrying terminal on the crystal raw material in a non-contact manner and detecting the change in atmospheric resistance between the current-carrying terminal and the ζO current-carrying terminal. Provide means to do so.

The atmosphere is usually a mixed gas, but according to experiments conducted by the present inventors, if a current-carrying terminal is provided on the melt without contact, and a voltage is applied between them with the Luzml as a counter electrode, 1
118 Current flows in the atmosphere, and this atmospheric resistance increases exponentially as the melt surface height decreases;
It became clear that 9, so OI! Although it is still unclear whether the reason for this is due to the high 1*txo ion conductivity or other mechanical factors, the present invention actively utilizes the findings from the H0 experiment.

〔Effect of the invention〕

According to the present invention, the height of the crystal jI material melt surface can be easily and accurately detected, and the JIc material replenishment can be performed continuously during crystal growth using the sound of the detection result. meet The bottle is [the supply is too much sea bream O Yang, this is [the bulk of the melt surface O]
Detection as information and control such as not interrupting raw material replenishment are also included in the package.

This lifting, the crystal side lν does not need to be interrupted, Ruth, r
By gradually decreasing EIllO1lltFi, it returns to the predetermined otmai. Further, according to the present invention, since the current-carrying terminal is installed without contacting the melt, it is possible to obtain a liquid level detection means that is excellent in durability and has a simple structure. Although it is necessary to insulate the current-carrying terminal so that it does not come in contact with the center O lead wire tRut I or the heater RC, this can be easily achieved by using an electrically insulating tube.

[Collection of invention examples]

This will be explained with reference to the drawings of example tubes.

1 shows the schematic configuration of the device, 1 is a quartz crystal, 2 is a silicon melt, 3 is a heater, 4 is a seed crystal, I is a pulling shaft,
6 is a root axis, and 1 is a nine-silicon crystal that has been pulled up.

This basic configuration remains the same as before. A current-carrying terminal t protected by a quartz tube 8 is placed on the Ruth MlO melt 2 .

The current-carrying terminal 9 is led outside the pr by a lead wire 10 and connected to a DC power source 11. The I-shaft 6 is grounded by an electric brush, and one end of the DC current fill 10 is connected to the logarithmic term @tars, so that current flows through the air between the current-carrying terminal 9 and the melt 1. It is now possible to detect. On Nitsu 11, raw materials wIJ and its raw materials are listed on Nitsu 1.
A funnel 14 is provided for replenishing. Raw material 1i
The J jtc is equipped with a nine-tilt adjustment mechanism (not shown) using a d-lenoid coil, and the raw material is supplied by controlling this J [sho@f/kt] with the output of the operational amplifier 110. The operational amplifier@110 output is also connected to the liquid level indicator II.

The crystal growth and raw material replenishment operations using this apparatus will be described next. First, polycrystalline silicon! After putting 00g and 900g of boron into tludll, melt it in the heater 3 to create a silicon melt. Seed crystal cha of the pulling shaft 5 provided above the nut 11.

After attaching the seed crystal 4 to the recess, the pulling shaft 5 is lowered to immerse the lower end of the seed crystal 4 in the silicon melt 2 in the melt 1, and then, while rotating the pulling shaft 5, Gradually pull up to the bottom of seed crystal 4! i! i crystal yt * next growth. (B)
The optimum rotation speed is 6 to 10 revolutions per minute, and the preferable pulling speed is 2 mm per minute.At this time, the rudder shaft 6 is also rotated at the same time, but the rudder shaft 6 is grounded with an electric brush.

The pulling begins before the diameter of crystal 1 becomes constant, and the raw material reservoir 13
The tilting mechanism 11 of the raw material reservoir 13 is operated so that the raw material is continuously fed into the granular polycrystalline silicon melt 11. Then, around the time when the diameter of the crystal 7 becomes constant, the pulling is performed by turning on the switch of the DC current @ 11 and applying a DC current to the energizing terminal 9, which is amplified by the energizing current St logarithmic operational amplifier 12, and its output When a signal is output to the display 15 that displays the liquid level height, VC! j Output to the solenoid coil of the inclination adjustment mechanism of the A-feed latch 13. According to experiments, the distance between the surface of the melt 2 and the current-carrying terminal 9 is x3.
9, the resistance R (Q/am'') between them is expressed by the following equation.

R=7.5xlO' @! Therefore, according to the actual noodles example, P (1,6
It is possible to pull crystals stably for a long time. Furthermore, continuous growth greatly increases the length of the input, greatly improving work efficiency. Additives such as impurities can also be prepared and placed in the raw material reservoir 13 in advance.Ninth, homogeneous crystals can be produced continuously by arbitrarily correcting once changes in exponential function impurities, which was difficult with conventional technology. be able to.

As a modification of the present invention, not only the crystal pulling apparatus but also the semiconductor casting method (Nakajastinda method) K can be applied.

The current-carrying terminal of the present invention can be used not only to control the supply of raw materials, but also to check the height of the melt surface using the current-carrying terminal.

It can also be used for diameter control using the Kralski method.

In this case, the rod-shaped ingot is in contact with the St liquid.

It is necessary to install the current-carrying terminal near the liquid surface in a non-contact manner. As a result, the mound of melt changes by 1 degree in proportion to the change in diameter, and this can be detected.

[Brief explanation of drawings]

The figure is a schematic diagram of a crystal pulling apparatus according to an embodiment of the present invention. 1...Rutsu〆, 2 silicoy melt, s...heater, 4
... Seed crystal, 5... Pulling axis, C... Ruth is the axis,
1... Pulling crystal 1.8... Quartz tube, 9... Current-carrying terminal, 1 No... DC power supply, 12... Logarithmic operational amplifier, I3... Raw material reservoir, 14...・Funnel, 1j...Liquid level height indicator.

Claims (1)

[Scope of Claims] An apparatus for growing a crystal by directly influencing a crystal raw material, a melt, and bringing a seed crystal into contact with the melt and pulling it up. A current-carrying terminal is installed on top of the non-contact part, and the ζO overcurrent terminal and crystal J
Change in resistance, [when detected]
ll- A crystal growth apparatus characterized in that it is equipped with a hand Rt for detecting a liquid image height of 1.