Method to manufacture low oxygen silicon single crystal and system for the same

Abstract

The present invention relates to the manufacture of a single crystal according to the Czochralski method (hereinafter referred to as the "CZ method"), and in particular, comprises the steps of: dividing the molten liquid present in a crucible into a first region below a critical point and a second region above a critical point based on the degree of growth of an ingot being pulled up from the molten liquid; heating only the molten liquid up to a pre-set critical liquid level based on the initial liquid level of the molten liquid; and a first adjustment step of adjusting the height of a magnetic field generating means so that a ZGP (Zero Gauss Plan) in the first region is positioned above the liquid level. The present invention relates to a method for manufacturing a low-oxygen silicon single crystal and a system based thereon, characterized by including: a second adjustment step of adjusting the height of the magnetic field generating means to position the ZGP below the liquid level in the second region; thereby limiting the heating area of ​​the crucible to reduce the temperature of the lower part of the crucible and minimize the amount of oxygen elution; and adjusting the oxygen concentration inflow path by changing the position of the ZGP (Zero Gauss Plan) in sections under Cusp magnetic field conditions, thereby manufacturing a single crystal ingot with an oxygen concentration of 3 ppma or less.

Description

Technology Field

[0001] An embodiment according to the present invention relates to the manufacture of a single crystal according to the Czochralski method (hereinafter referred to as the "CZ method"), and in particular, to a method for manufacturing a low-oxygen silicon single crystal and a system according thereto for manufacturing a single crystal ingot with an oxygen concentration of 3 ppma or less by limiting the heating area of ​​the crucible to reduce the temperature of the bottom of the crucible and minimize the amount of oxygen leaching, and by adjusting the oxygen concentration inflow path by changing the position of the Zero Gauss Plan (ZGP) section by section under Cusp magnetic field conditions. Background Technology

[0002] Generally, the CZ method is widely used as a method for growing large-diameter ingots. Referring to FIG. 1 which shows a method for growing a single crystal ingot according to the conventional CZ method, first, silicon is introduced into a quartz crucible (10), and the quartz crucible (10) is heated by a heating element (40) to create a molten liquid (M: Melt) in which the silicon is melted.

[0003] Afterwards, a seed crystal connected to a tension cable (2) is immersed in the molten liquid (M), and the seed crystal is rotated in a certain direction and pulled up so that crystallization occurs at the interface between the molten liquid (M) and the seed crystal, thereby growing the silicon ingot (1) in the order of a neck part (1N), a shoulder part (1S) with increasing diameter, a cylindrical body part (1B) with constant diameter, and finally a tail part with decreasing diameter.

[0004] In the above-described CZ method, natural convection of the molten liquid (M) occurs due to heating of the heating element, and forced convection of the molten liquid (M) occurs due to rotation of the crystal and the crucible (10). These natural convection and forced convection interact with each other to form a complex convection pattern within the molten liquid (M).

[0005] In particular, as the ingot (1) grows from the neck (1N) to the solder (1S) and then to the body (1B), the temperature gradient in the vertical direction of the crystal changes, and the convection pattern of the molten liquid (M) also changes due to the decrease in the volume of the molten liquid (M). These changes affect the quality of the crystal and cause the quality of the crystal to change according to the crystal length.

[0006] In addition, the convection pattern of the molten liquid (M) is closely related to the quality of the crystal, and it is known that applying a magnetic field to the molten liquid (M) to control the convection of the molten liquid (M) is an effective method. The magnetic field used at this time is broadly classified into a horizontal magnetic field, a vertical magnetic field, and a cusp magnetic field depending on the distribution of magnetic field lines.

[0007] Among these, the cusp magnetic field forms a circular magnetic field application part (51, 52) around the crucible, consisting of an upper coil (51A, 51B) and a lower coil (52A, 52B), and is formed by supplying current of opposite directions (or different polarities) to the upper coil (51) and the lower coil (52).

[0008] The shape of the above cusp magnetic field consists of the ZGP (Zero Gauss Plane), which represents the position where the vertical component of the magnetic field is zero in two dimensions, and the upper magnetic field (G upper ) and lower magnetic field (G lower R(G) calculated as the ratio of ) intensity lower / G upper It can be explained as follows. In addition, in the case of the above cusp magnetic field, depending on the position of the magnetic field, a region is generated where there is no influence of the perpendicular magnetic field, and this region is called ZGP.

[0009] The above upper magnetic field (G upper ) and the lower magnetic field (G lower When the strength of ) is the same (R=1), the upper magnetic field (G upper ) and the lower magnetic field (G lower) In the middle, a magnetic pole is opposed, and the upper magnetic field (G upper ) and the lower magnetic field (G lower A ZGP is formed in the form of a horizontal plane at the center of ). And, the lower magnetic field (G lower The strength of ) is the upper magnetic field (G upper When the intensity is greater than (R>1), the ZGP is formed in the shape of a parabola with a convex top.

[0010] Typically, the distribution of the cusp magnetic field can be controlled in various forms by adjusting the current strength applied to each coil, the number of windings of the upper and lower coils, and the positions of the upper and lower coils.

[0011] Meanwhile, with the recent high integration of semiconductor devices, the quality standards required by manufacturers for wafers are improving. As a result, the required range for oxygen concentration, a key quality characteristic, has narrowed and has decreased significantly compared to the past, and there is now a demand for wafers that are free from single-crystal defects. The problem to be solved

[0012] One embodiment of the present invention aims to resolve the problems described above.

[0013] A method for manufacturing a low-oxygen silicon single crystal and a system thereunder according to one embodiment of the present invention are particularly intended to produce a single crystal ingot with an oxygen concentration of 3 ppma or less by limiting the heating area of ​​the crucible during the single crystal manufacturing process according to the CZ method to reduce the temperature of the lower part of the crucible and minimize the amount of oxygen elution, and by adjusting the oxygen concentration inflow path by changing the position of the Zero Gauss Plan (ZGP) section by section under Cusp magnetic field conditions. means of solving the problem

[0014] The feature of the method for manufacturing a low-oxygen silicon single crystal according to the present invention for achieving the above-described purpose is to include: a step of dividing the molten liquid present in a crucible into a first region below a predetermined critical point and a second region above the said critical point based on the degree of growth of an ingot being pulled up while rotating; a step of heating only the molten liquid up to a predetermined critical liquid level based on the initial liquid level of the said molten liquid; a first adjustment step of adjusting the height of a magnetic field generating means so that a ZGP (Zero Gauss Plan) is positioned above the liquid level in the first region; and a second adjustment step of adjusting the height of the magnetic field generating means so that the ZGP is positioned below the liquid level in the second region.

[0015] An additional feature of the method for manufacturing a low-oxygen silicon single crystal according to the present invention for achieving the above-described purpose is that the first region has an ingot growth degree of 60% or less, and the second region has an ingot growth degree of 60% or more.

[0016] As an additional feature of the method for manufacturing a low-oxygen silicon single crystal according to the present invention for achieving the above-described purpose, the critical liquid level is 30% to 40% when the initial liquid level is considered as 100% based on the bottom surface of the crucible.

[0017] As an additional feature of the method for manufacturing a low-oxygen silicon single crystal according to the present invention for achieving the purpose described above, the first adjustment step is to adjust the height of the magnetic field generating means so that the ZGP is positioned at +30mm to +100mm above the liquid level.

[0018] As an additional feature of the method for manufacturing a low-oxygen silicon single crystal according to the present invention for achieving the purpose described above, the first adjustment step is to make the strength of the magnetic field generated by the magnetic field generating means 1,000 gauss or more.

[0019] As an additional feature of the method for manufacturing a low-oxygen silicon single crystal according to the present invention for achieving the purpose described above, the second adjustment step is to adjust the height of the magnetic field generating means so that the ZGP is positioned at -20mm to -60mm below the liquid level.

[0020] The feature of the low-oxygen silicon single crystal manufacturing system according to the present invention for achieving the above-described purpose is a single crystal growth apparatus using the Czochralski method comprising: a crucible for receiving a semiconductor melt; a heater installed around the side wall of the crucible; a lifting means for lifting a single crystal from the semiconductor melt received in the crucible by a seed crystal; and a magnetic field device installed around the crucible; wherein the heater limits the length of the heating element to within a critical range so as to heat only the solution within a range up to a pre-set critical liquid level based on the initial liquid level of the solution; and the magnetic field device is positioned such that, when divided into a first region below a pre-set critical point and a second region above the critical point based on the degree of growth of the ingot lifted from the solution present in the crucible, the ZGP (Zero Gauss Plan) is positioned above the liquid level in the first region and the ZGP is positioned below the liquid level in the second region.

[0021] An additional feature of the low-oxygen silicon single crystal manufacturing system according to the present invention for achieving the above-described purpose is that the critical liquid level is 30% to 40% when the initial liquid level is considered as 100% based on the bottom surface of the crucible.

[0022] An additional feature of the low-oxygen silicon single crystal manufacturing system according to the present invention for achieving the above-described purpose is that the length of the heating element has a range of 250 mm to 350 mm.

[0023] As an additional feature of the low-oxygen silicon single crystal manufacturing system according to the present invention for achieving the purpose described above, the magnetic field device slides up and down according to the control of the control unit based on a detection signal from a liquid level measuring means that measures the liquid level of the solution.

[0024] As another additional feature of the low-oxygen silicon single crystal manufacturing system according to the present invention for achieving the purpose described above, the first region is such that the degree of ingot growth is within 60%.

[0025] As an additional feature of the low-oxygen silicon single crystal manufacturing system according to the present invention for achieving the purpose described above, the magnetic field device is configured to position the ZGP at +30mm to +100mm above the liquid level detected by the liquid level measuring means under the control of the control unit.

[0026] Another additional feature of the low-oxygen silicon single crystal manufacturing system according to the present invention for achieving the above-described purpose is that the strength of the magnetic field generated by the magnetic field device is 1,000 gauss or more.

[0027] As another additional feature of the low-oxygen silicon single crystal manufacturing system according to the present invention for achieving the purpose described above, the second region is such that the degree of ingot growth is 60% or more.

[0028] As an additional feature of the low-oxygen silicon single crystal manufacturing system according to the present invention for achieving the purpose described above, the magnetic field device is positioned at -20mm to -60mm below the liquid level detected by the liquid level measuring means under the control of the control unit. Effects of the invention

[0029] According to one embodiment of the present invention, a method for manufacturing a low-oxygen silicon single crystal and a system according thereto are provided, thereby limiting the heating area of ​​the crucible during the single crystal manufacturing process according to the CZ method to reduce the temperature of the lower part of the crucible and minimize the amount of oxygen elution, and by changing the position of the Zero Gauss Plan (ZGP) in sections under Cusp magnetic field conditions to adjust the oxygen concentration inflow path, it is possible to manufacture a single crystal ingot with an oxygen concentration of 3 ppma or less. Brief explanation of the drawing

[0030] Figure 1 is an illustrative diagram explaining a method for manufacturing silicon single crystals according to the general Czochralski method. FIGS. 2 and 3 are exemplary drawings for explaining a manufacturing apparatus to which the low-oxygen silicon single crystal manufacturing method according to the present invention is applied. FIGS. 4 and 5 are exemplary diagrams of the magnetic field resulting from the position adjustment of the ZGP (Zero Gauss Plan) during the process of applying the low-oxygen silicon single crystal manufacturing method according to the present invention. FIG. 6 is a graph of the oxygen concentration of an ingot to which the low-oxygen silicon single crystal manufacturing method according to the present invention is applied. Specific details for implementing the invention

[0031] Embodiments according to the present invention may be modified in various different forms, and the scope of the present invention should not be interpreted as being limited to the embodiments described below. The embodiments of the present invention are provided to more fully explain the present invention to those with average knowledge in the art.

[0032] Additionally, relational terms such as "first" and "second," "upper" and "lower," etc., used below, may be used solely to distinguish one entity or element from another, without necessarily requiring or implying any physical or logical relationship or order between such entities or elements.

[0033] Hereinafter, a method for manufacturing a low-oxygen silicon single crystal according to the present invention and a system based thereon will be described with reference to the attached drawings.

[0034] Figures 2 and 3 attached are exemplary diagrams for explaining a manufacturing apparatus to which the low-oxygen silicon single crystal manufacturing method according to the present invention is applied, Figures 4 and 5 are exemplary diagrams of a magnetic field according to the position adjustment of a Zero Gauss Plan (ZGP) during the process of applying the low-oxygen silicon single crystal manufacturing method according to the present invention, and Figure 6 is a graph of the oxygen concentration of an ingot to which the low-oxygen silicon single crystal manufacturing method according to the present invention is applied.

[0035] As shown in the attached FIGS. 2 and 3, the manufacturing apparatus to which the low-oxygen silicon single crystal manufacturing method according to the present invention is applied introduces silicon into a quartz crucible (10) and heats the quartz crucible (10) by means of a heating element (100) to melt the silicon and produce a molten liquid (M: Melt).

[0036] Afterwards, a seed crystal connected to a tension cable (2) is immersed in the molten liquid (M), and the seed crystal is rotated in a certain direction and pulled up so that crystallization occurs at the interface between the molten liquid (M) and the seed crystal, thereby growing in the order of a neck part (1N), a shoulder part (1S) with increasing diameter, a cylindrical body part (1B) with constant diameter, and finally a tail part with decreasing diameter, to grow a single crystal silicon ingot (1).

[0037] At this time, the crucible support (20) supporting the quartz crucible (10) rotates in the opposite direction to the rotation direction of the ingot (1) by means of the rotation axis (30) to promote the growth of the ingot (1).

[0038] At this time, the heating element (100) limits the length of the heating part to within a critical range so as to heat only the solution within a range up to a pre-set critical liquid level based on the initial liquid level of the molten liquid (M).

[0039] In the present invention, the length of the heating element (100) is limited to a range of 250 mm to 350 mm. By limiting the length range, the molten liquid (M) is heated only up to a level of 30% to 40% when the initial liquid level of the molten liquid (M) is considered as 100% based on the bottom surface (or bottom surface) of the crucible (10), and the molten liquid (M) corresponding to the lower region is not heated, thereby reducing the lower temperature of the crucible (10) and minimizing the amount of oxygen leached from the molten liquid (M).

[0040] In addition, the convection pattern of the molten liquid (M) is closely related to the quality of the crystal, and to control the convection of the molten liquid (M), a circular magnetic field application section (200A, 200B) is formed around the crucible (10) to apply a magnetic field to the molten silicon. This section consists of an upper coil (210A, 210B) and a lower coil (220A, 220B), and is formed by supplying currents of opposite directions (or different polarities) to the upper coil (210A, 210B) and the lower coil (220A, 220B).

[0041] At this time, the magnetic field application unit (200A, 200B) slides up and down along the sliding support unit referred to as reference numbers 230A and 230B, and the position adjustment of the magnetic field application unit (200A, 200B) is performed by a control unit (not shown), and the control unit adjusts the oxygen concentration inflow path by changing the ZGP (Zero Gauss Plan) position based on the detection signal from the liquid level measuring means (60) that measures the liquid level of the molten liquid (M).

[0042] To further explain with reference to the attached FIGS. 4 and 5, based on the degree of growth of the ingot (1) being pulled up from the molten liquid (M) present in the crucible (10), it is divided into a first region below the critical point (ingot growth degree within 60%) and a second region above the critical point (ingot growth degree 60% or more).

[0043] At this time, as shown in Fig. 4 with the ZGP (Zero Gauss Plan) attached in the first region, the position of the magnetic field application unit (200A, 200B) is adjusted to be located at +30mm to +100mm above the liquid level based on the liquid level detected by the liquid level measuring means (60), and in the second region, as shown in Fig. 5 with the ZGP attached, the position of the magnetic field application unit (200A, 200B) is adjusted to be located at -20mm to -60mm below the liquid level based on the liquid level detected by the liquid level measuring means (60).

[0044] In addition, in the first region, it is preferable to make the magnetic field strength generated by the magnetic field application unit (200A, 200B) 1,000 gauss or more.

[0045] Therefore, the process of oxygen leaching out from the molten liquid (M) and distributed in the working environment flowing into the ingot (1) can be minimized.

[0046] By providing a low-oxygen silicon single crystal manufacturing method and a system according to the present invention as described above, the area of ​​the crucible being heated during the single crystal manufacturing process according to the CZ method is limited to reduce the temperature of the lower part of the crucible and minimize the amount of oxygen elution. Additionally, by changing the position of the ZGP (Zero Gauss Plan) in sections under Cusp magnetic field conditions to adjust the oxygen concentration inflow path, it is possible to manufacture a single crystal ingot with an average oxygen concentration of 3 ppma or less according to the solidification rate (solidification rate) of the ingot (1) as shown in the attached Fig. 6.

[0047] Although preferred embodiments of the present invention have been illustrated and described above, the present invention is not limited to the specific embodiments described above. It is understood that various modifications can be made by those skilled in the art without departing from the essence of the invention as claimed in the patent claims, and such modifications should not be understood individually from the technical spirit or perspective of the present invention. Explanation of the symbols

[0048] 1 : Ingot 2 : Tension cable 10: Quartz crucible 20 : Crucible support 30 : Rotation axis 40, 100: Heating element M: Molten liquid 51, 52, 200A, 200B: Magnetic field application section 60: Liquid level measuring means

Claims

Claim 1 A method for manufacturing a low-oxygen silicon single crystal, characterized by comprising: a step of dividing the molten liquid present in a crucible into a first region below a preset critical point and a second region above the preset critical point based on the degree of growth of an ingot being pulled up from the molten liquid; a step of heating only the molten liquid up to a preset critical liquid level based on the initial liquid level of the molten liquid; a first adjustment step of adjusting the height of a magnetic field generating means in the first region to position a ZGP (Zero Gauss Plan) above the liquid level; and a second adjustment step of adjusting the height of the magnetic field generating means in the second region to position the ZGP below the liquid level. Claim 2 A method for manufacturing a low-oxygen silicon single crystal according to claim 1, wherein the first region is characterized by an ingot growth degree of within 60%. Claim 3 A method for manufacturing a low-oxygen silicon single crystal according to claim 1, wherein the second region has an ingot growth degree of 60% or more. Claim 4 A method for manufacturing a low-oxygen silicon single crystal according to claim 1, characterized in that the critical liquid level is 30% to 40% when the initial liquid level is considered as 100% based on the bottom surface of the crucible. Claim 5 A method for manufacturing a low-oxygen silicon single crystal according to claim 1, wherein the first adjustment step is characterized by adjusting the height of the magnetic field generating means to position the ZGP at +30mm to +100mm above the liquid level. Claim 6 A method for manufacturing a low-oxygen silicon single crystal according to claim 5, wherein the first adjustment step is characterized by making the strength of the magnetic field generated by the magnetic field generating means 1,000 gauss or more. Claim 7 A method for manufacturing a low-oxygen silicon single crystal according to claim 1, wherein the second adjustment step is characterized by adjusting the height of the magnetic field generating means to position the ZGP at -20mm to -60mm below the liquid level. Claim 8 A single crystal growth apparatus using the Czochralski method, comprising: a crucible for receiving a semiconductor melt; a heater installed around the side wall of the crucible; a lifting means for lifting a single crystal from the semiconductor melt received in the crucible by a seed crystal; and a magnetic field device installed around the crucible; wherein the heater limits the length of the heating element to within a critical range so as to heat only the solution within a range up to a pre-set critical liquid level based on the initial liquid level of the solution; and wherein the magnetic field device is positioned such that, when divided into a first region below a pre-set critical point and a second region above the critical point based on the degree of growth of the ingot lifted from the solution present in the crucible, the ZGP (Zero Gauss Plan) is positioned above the liquid level in the first region and the ZGP is positioned below the liquid level in the second region. Claim 9 A low-oxygen silicon single crystal manufacturing system according to claim 8, characterized in that the critical liquid level is 30 to 40% when the initial liquid level is considered as 100% based on the bottom surface of the crucible. Claim 10 A low-oxygen silicon single crystal manufacturing system according to claim 8, characterized in that the length of the heating element has a range of 250 mm to 350 mm. Claim 11 A low-oxygen silicon single crystal manufacturing system according to claim 8, wherein the magnetic field device slides up and down according to the control of a control unit based on a detection signal from a liquid level measuring means for measuring the liquid level of the solution. Claim 12 A low-oxygen silicon single crystal manufacturing system according to claim 11, wherein the first region is characterized by an ingot growth degree of within 60%. Claim 13 A low-oxygen silicon single crystal manufacturing system according to claim 12, wherein the magnetic field device positions the ZGP at +30mm to +100mm above the liquid level in the first region according to the control of the control unit. Claim 14 A low-oxygen silicon single crystal manufacturing system according to claim 13, characterized in that the magnetic field strength generated by the magnetic field device is 1,000 gauss or more. Claim 15 A low-oxygen silicon single crystal manufacturing system according to claim 11, wherein the second region is characterized by an ingot growth degree of 60% or more. Claim 16 A low-oxygen silicon single crystal manufacturing system according to claim 15, wherein the magnetic field device is positioned at -20mm to -60mm below the liquid level in the second region under the control of the control unit.

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