KR101390802B1 - Method for manufacturing silicon single crystal and melt of silicon single crystal - Google Patents

Abstract

Examples include (a) adding sulfuric acid to the dopant to form a solid acid catalyst; (b) adding an anti-volatilization agent to the resultant of the step (a) to bond the anti-volatilization agent to the remaining dopant; And (c) injecting the resultant of step (b) into a silicon melt.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a method of manufacturing a silicon single crystal and a silicon single crystal melt,

The present invention relates to a method of manufacturing a silicon single crystal and a method of manufacturing a silicon single crystal by preparing a silicon single crystal melt by adding a dopant and an anti-volatilization agent.

Silicon used as a material for semiconductor devices and solar cells is naturally present in the form of oxide (silicate) or silicate. And, when the silica which is the main component of silica is put into the electric furnace together with the coke and subjected to the chemical treatment after melting, a powdery silicon having a purity of about 98% called metalloid silicon is obtained.

When the powdered silicon is converted to silicon in the form of gas, it is annealed to obtain polycrystalline silicon having a purity of about 99%. Since silicon wafers used in integrated circuit fabrication must be monocrystalline, a physical refining method is used to convert polycrystalline silicon into monocrystalline silicon.

In order to manufacture a wafer, a silicon single crystal must be grown as an ingot. For this purpose, a czochralski (CZ) method or a floating zone (FZ) method may be applied. At this time, a silicon wafer used as a substrate of a semiconductor device can be doped with a dopant in the growth process of a silicon single crystal so as to have an appropriate resistivity value. A p-type or n-type dopant may be added.

However, the conventional silicon single crystal growth process has the following problems.

A dopant is added to a silicon single crystal melt for producing a silicon single crystal as described above, but a large amount of the dopant is volatilized in the silicon melt, resulting in a large loss. Further, when the high-volatility dopant is volatilized, the doping concentration of the dopant in the silicon single crystal melt is decreased, and the silicon single crystal having the desired doping concentration or characteristics can not be grown.

The embodiment is intended to prevent the volatilization of the dopant in the production process of the silicon single crystal ingot and to improve the silicon doping effect.

Examples include (a) adding sulfuric acid to the dopant to form a solid acid catalyst; (b) adding an anti-volatilization agent to the resultant of the step (a) to bond the anti-volatilization agent to the remaining dopant; And (c) injecting the resultant of step (b) into a silicon melt.

The dopant may be an n-type dopant or a p-type dopant.

The dopant may be at least one of As, Al, P, Sb, Fe, Co, Zr, Zn, Mg,

Solid acid catalyst _{B (HSO 4) 3, Al} (HSO 4) 3 and _{Fe (HSO 4) 3, Co} (HSO 4) 3, Zr (HSO 4) 4, Zn (HSO 4) 2, Mg (HSO 4) ₂ , Ca (HSO ₄ ) ₂ , and As (HSO ₄ ) ₃ .

The concentration of sulfuric acid may be from 90% to 98%.

0.1 milliliter to 1000 milliliters of the sulfuric acid per microgram of dopant may be added.

The molar concentration of the anti-volatilization agent may be added above the molar concentration of the dopant.

The anti-volatilization agent may be a sugar alcohol.

The anti-volatilization agent may be at least one of mannitol, sorbitol, maltitol, inositol, dulcitol and erithritol.

Other embodiments include silicone melt; Dopant; A solid acid catalyst in which the dopant and sulfuric acid are combined; And a complex in which the dopant and the anticorrosion agent are combined. The present invention provides a silicon single crystal melt which is at least one of dulcitol and erythritol.

In the method for manufacturing a silicon single crystal and the silicon single crystal melt according to the embodiment, sulfuric acid is added to a high volatility dopant to form a solid acid catalyst. When the addition of an antioxidant is further performed, the dopant and the antivolvent are combined to form a complex, It is possible to prevent volatilization of the dopant and to reduce the dopant cost and improve the doping effect.

1 is a view showing a silicon single crystal ingot growing apparatus,
2 is a flowchart showing a method of manufacturing a silicon single crystal,
3 is a graph showing input concentrations and analytical concentrations of the elements injected into the silicon single crystal melt.

Embodiments will now be described with reference to the accompanying drawings.

In the description of embodiments according to the present invention, in the case of being described as being formed "on or under" of each element, the upper (upper) or lower (lower) or under are all such that two elements are in direct contact with each other or one or more other elements are indirectly formed between the two elements. Also, when expressed as "on or under", it may include not only an upward direction but also a downward direction with respect to one element.

The thickness and size of each layer in the drawings are exaggerated, omitted, or schematically shown for convenience and clarity of explanation. Also, the size of each component does not entirely reflect the actual size.

Fig. 1 is a view showing a silicon single crystal ingot growing apparatus, and Fig. 2 is a flowchart showing a manufacturing method of a silicon single crystal.

Ga and other impurities may be added as a dopant during the growth of the silicon single crystal ingot using the growth apparatus of the silicon single crystal ingot of Fig. 1. In this embodiment, sulfuric acid and an anti-volatilization agent are added to the dopant Thereby preventing the dopant from being volatilized, thereby reducing the dopant cost and improving the doping concentration.

To this end, sulfuric acid (H ₂ SO ₄ ) may be added to the dopant to form a solid acid catalyst. As the dopant, p-type or n-type dopants can be used. These dopants can be classified into a high melting point dopant whose melting point is higher than that of silicon and a low melting point dopant whose melting point is lower than the melting point of silicon.

At this point, sulfuric acid (H ₂ SO ₄₎ The ionization reaction is primary in the ionization reaction H ⁺ and HSO ₄ a ^- is ionized in this case the ionization constant of 10 ² degree, and the secondary HSO ₄ in the ionization ^reaction is H ⁺ and HSO ₄ ^{2 -} , and the ionization constant at this time is about 1.2 × 10 ^-2 . Thus, the ions in solution are present as H ⁺ and HSO ₄ ^- and the dopants described above and HSO ₄ ^- combine to form a solid acid catalyst whose formula is M (HSO 4) _n , where M is the dopant And n is an integer.

The dopant is selected from the group consisting of As (arsenic), Al (aluminum), P (phosphorus), Sb (antimony), Fe (iron), Co (cobalt), Zr (zirconium) ) And B (boron) may be used. The dopant is divided into a low-melting-point dopant having a melting point lower than that of silicon and a high-melting point dopant having a melting point higher than that of silicon. Accordingly, the dopant may be added to the silicon melt.

The above-mentioned dopants are a group 5 element or a group 3 element having one or more electrons than silicon (Si). All the compounds formed by combining the above-described elements with an acid have a boiling point higher than room temperature It can have high volatility.

The addition of sulfuric acid may be carried out by adding from 0.1 milliliter (s) to 1,000 milliliters of sulfuric acid per microgram of dopant. Since sulfuric acid acts as a catalyst, if it is put in too much amount, it may be difficult to act as an obstructing substance in the reaction or to expect a better effect than a proper amount. In addition, when too little sulfuric acid is added, it may not sufficiently serve as a catalyst.

Then, sulfuric acid having a concentration of 90% (percent) to 98% can be combined with the above-mentioned dopant. If the concentration of sulfuric acid is too small, it may not play the same role as strong sulfuric acid.

For example, boron is combined with sulfuric acid to form B (HSO ₄ ) ₃ , aluminum to form Al (HSO ₄ ) ₃ , iron to form Fe (HSO ₄ ) ₃ , ₄ ) ₃ , cobalt Co (HSO ₄ ) ₃ , zirconium Zr (HSO ₄ ) ₄ , zinc Zn (HSO ₄ ) ₂ , magnesium Mg (HSO ₄ ) ₂ , calcium Ca ₄ ) ₂ and arsenic as As (HSO ₄ ) ₃ , respectively. The above-mentioned solid acid catalyst can serve as a catalyst for promoting the bonding of the anti-volatilization agent such as mannitol in the remaining dopant in the step to be described later.

Then, an anti-volatilization agent may be added to the resultant product to bind the remaining anti-volatilization agent to the dopants. That is, a part of the dopant binds with sulfuric acid to form a solid acid catalyst, and the remaining unreacted dopant can further bind to the anti-volatilization agent to form a complex.

As the antioxidant, sugar alcohols can be used. Specifically, any one of mannitol, sorbitol, maltitol, inositol, dulcitol and erithritol can be used. have.

At this time, the above-mentioned anti-volatilization agent may be added at a molar concentration or more of the dopant.

If the sulfuric acid and the anti-volatilization agent are simultaneously supplied to the dopant in the same volume, the dopant can bind faster with the anti-volatilizing agent. At the same volume, since the molar concentration of the dopant is higher than the molarity of the sulfuric acid, the remaining dopant can bind to the sulfuric acid after the dopant is first bound to the anti-volatilization agent.

Then, sulfuric acid is added to the above-described dopant to form a solid acid catalyst, and further, an anti-volatilization agent is supplied, and the resultant bonded with the remaining dopant can be injected into the silicon melt.

At this time, the method of injecting the high melting point dopant and the low melting point dopant may be different.

Boron, which is a high melting point dopant, has a melting point of about 2180 캜, which is higher than the melting point of silicon of 1412 캜. Therefore, the polycrystalline silicon, which is the preparation step for growing silicon single crystal, is loaded on the quartz crucible with the polycrystalline silicon A dopant may be added to the silicon melt.

Since the melting point of low melting point dopants such as antimony, phosphorus, and arsenic is low, the polycrystalline silicon can be melted and vaporized before the polycrystalline silicon is completely melted in the melting step of the first polycrystalline silicon in the silicon single crystal growing process. Therefore, After silicon is completely dissolved, doping can be performed by spraying a low melting point dopant on the surface of the molten silicon.

Then, the above-mentioned resultant material, that is, a material in which sulfuric acid and an anti-volatilization agent are sequentially or simultaneously bonded to the dopant is injected into a silicon melt. At this time, the above-mentioned resultant is put into the crucible 20, and the inside of the chamber 10 is treated with vacuum, and then argon (Ar) gas is injected. Then, the crucible 20 is heated to melt the raw material silicon.

The silicon single crystal ingot growing apparatus 100 according to the present invention includes a chamber 10 in which a space for growing a silicon single crystal ingot 14 from a silicon (Si) melt is formed, a chamber 10 in which the silicon single crystal melt is accommodated A crucible 20 for heating the crucible 20; a heating unit 40 for heating the crucible 20; a crucible 20 for cutting off the heat of the heating unit 40 toward the silicon single crystal ingot; A seed chuck 18 for fixing a seed (not shown) for growing the silicon single crystal ingot 14, a crucible 22 rotated by a driving means, And a rotary shaft 30 for rotating the rotary shaft 30 upward.

The chamber 10 may be in the form of a cylinder having a cavity formed therein and the crucibles 20 and 22 are located in a central region of the chamber 10. The crucibles 20 and 22 are in the shape of a generally concave vessel so that the silicon single crystal melt can be received. The crucible may comprise a quartz crucible 20 in direct contact with the silicon single crystal melt and a graphite crucible 22 surrounding the quartz crucible 20 and supporting the quartz crucible 20. [

The silicon raw material is mixed with the above-mentioned resultant, and the molten silicon melt may include a silicon melt, the above-mentioned dopant, a solid acid catalyst in which a dopant and sulfuric acid are bonded, and a complex in which a dopant and an anti-volatilization agent are combined.

The solid acid catalyst may be B (HSO ₄ ) ₃ (Al 2 O 3), and may be an n-type dopant or a p-type dopant. Specific examples of the dopant include As, Al, P, Sb, Fe, Co, Zr, Zn, , Al (HSO _{4) 3} and _{Fe (HSO 4) 3, Co} (HSO 4) 3, Zr (HSO 4) 4, Zn (HSO 4) 2, Mg (HSO 4) 2, Ca (HSO 4) 2 and As (HSO ₄ ) ₃ , and the like.

The anti-volatilization agent may be a sugar alcohol, and specifically may be, for example, mitool, sorbitol, maltitol, inositol, dulcitol, erythritol and the like.

3 is a graph showing input concentrations and analytical concentrations of the elements injected into the silicon single crystal melt. It can be seen that elements such as boron, phosphorus, arsenic and antimony, that is, dopants, are analyzed in the silicon single crystal melt almost in the same manner as the input concentration, so that they are not volatilized with time and have almost no concentration fluctuation.

After the silicon melt is melted in the crucible, an ingot is grown in the silicon single crystal ingot growing apparatus 100. In the case of the Czochralski method, a seed single crystal is dipped on the surface of the silicon melt, Single crystals are grown at the bottom of the seed from the melt and grown at the neck part through the necking process in the early growth part.

Then, a monocrystalline ingot is grown through a body growth process when a certain length is reached through a shouldering process in which the diameter of the single crystal gradually expands. At this time, the body of the silicon monocrystal ingot is grown over a certain length while lifting up the seed chuck by using the lifting device installed on the growth furnace.

In addition, a slicing process in which the grown ingot is sliced into thin chips on a wafer-by-wafer basis, a lapping process for improving the flatness while polishing the wafer to a desired wafer thickness, an etching process for removing damage to the wafer, A polishing process for improving the surface mirroring and flatness, and a cleaning process for removing contaminants on the surface of the wafer to produce a silicon wafer.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, This is possible.

Therefore, the scope of the present invention should not be limited to the described embodiments, but should be determined by the equivalents of the claims, as well as the claims.

10: chamber 14: single crystal ingot
18: seed chuck 20, 22: crucible
30: rotating shaft 40: heating part
60: upper heat insulating portion 100: silicon single crystal ingot growth device

Claims (15)

(a) adding sulfuric acid to the dopant to form a solid acid catalyst;
(b) adding an anti-volatilization agent to the resultant of the step (a) to bond the anti-volatilization agent to the remaining dopant; And
(c) injecting the resultant of step (b) into a silicon melt. The method according to claim 1,
Wherein the dopant is an n-type dopant or a p-type dopant. The method according to claim 1,
Wherein the dopant is at least one of As, Al, P, Sb, Fe, Co, Zr, Zn, Mg, Ca and B. The method according to claim 1,
The solid acid catalyst is _{B (HSO 4) 3, Al} (HSO 4) 3 and _{Fe (HSO 4) 3, Co} (HSO 4) 3, Zr (HSO 4) 4, Zn (HSO 4) 2, Mg (HSO 4 ) ₂ , Ca (HSO ₄ ) ₂ , and As (HSO ₄ ) ₃ . The method according to claim 1,
Wherein the concentration of the sulfuric acid is 90% to 98%. The method according to claim 1,
Wherein the sulfuric acid is added in an amount of 0.1 milliliter to 1000 milliliters per microgram of the dopant. The method according to claim 1,
Wherein the molar concentration of the anti-volatilization agent is added at a molarity or more of the dopant. The method according to claim 1,
Wherein the volatilization inhibitor is a sugar alcohol. The method according to claim 1,
Wherein the volatilization inhibitor is at least one of mannitol, sorbitol, maltitol, inositol, dulcitol and erithritol. Silicone melt;
Dopant;
A solid acid catalyst in which the dopant and sulfuric acid are combined; And
And a complex in which the dopant and the anti-volatilization agent are combined. 11. The method of claim 10,
Wherein the dopant is an n-type dopant or a p-type dopant. 11. The method of claim 10,
Wherein the dopant is at least one of As, Al, P, Sb, Fe, Co, Zr, Zn, Mg, Ca and B. 11. The method of claim 10,
The solid acid catalyst is _{B (HSO 4) 3, Al} (HSO 4) 3 and _{Fe (HSO 4) 3, Co} (HSO 4) 3, Zr (HSO 4) 4, Zn (HSO 4) 2, Mg (HSO 4 ) ₂ , Ca (HSO ₄ ) ₂ , and As (HSO ₄ ) ₃ . 11. The method of claim 10,
The anti-volatilization agent is a silicon monocrystal melt which is a sugar alcohol. 11. The method of claim 10,
Wherein the volatilization inhibitor is at least one of mannitol, sorbitol, maltitol, inositol, dulcitol and erithritol.

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