JP2937109B2 - Single crystal manufacturing apparatus and manufacturing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus and a method for producing a single crystal such as silicon and the like. The present invention relates to a manufacturing apparatus suitable for precise control of concentration.

[0002]

2. Description of the Related Art At present, single crystals such as silicon are often produced by the Czochralski method. In the Czochralski method, a single crystal is grown by being pulled up from a silicon melt in a quartz crucible, and thus the grown crystal contains a large amount of oxygen eluted from the quartz (SiO ₂ ) in the crucible. For this reason, even if it is repeatedly subjected to heat treatment in the manufacturing process of an IC or an LSI, a slip or a warp hardly occurs. Further, the oxygen precipitate inside has a function of forming a high-density defect layer by heat treatment at around 1000 ° C. and reducing impurities present in the surface region of the wafer (so-called intrinsic gettering function).

FIG. 8 is a schematic sectional view showing the state of implementation of the Czochralski method. The crucible 1 has a double structure, the inside being a quartz container 1a and the outside being a graphite container 1b. A heater 2 is provided outside the crucible 1,
The melt 5 of the crystal raw material melted by the heater is accommodated therein. By bringing the lower end of the seed crystal 3 into contact with the surface of the melt 5 and pulling it upward, the single crystal 4 is grown at the lower end. These parts,
The members are housed in a water-cooled metal chamber 6 and constitute a single crystal manufacturing apparatus as a whole.

During the pulling of the single crystal, a high-purity argon gas as an inert gas is constantly flowed from the upper central portion of the metal chamber 6 to form a gas flow 30. Gas flow 30
Is accompanied by silicon monoxide (SiO) evaporating from the surface of the silicon melt 5 and carbon monoxide (CO) generated by a reaction between the silicon monoxide and a high-temperature member such as the heater 2 or the graphite container 1b. As a result, a gas flow 31 flows down the inner and outer peripheral surfaces of the heater 2 and is discharged from the discharge port 8.

The flow of the argon gas in the metal chamber 6 is a complicated turbulent flow, and local stagnation occurs. Therefore, the deposit of silicon monoxide is deposited on the ceiling of the metal chamber 6 in a layered or lump form. Adheres to The precipitated silicon monoxide fine powder or lump falls onto the surface of the melt 5 and is taken into the crystal growth interface, which causes dislocation of the crystal.

[0006] On the other hand, if carbon monoxide is not properly discharged, it contaminates the silicon melt and mixes into the single crystal, causing a crystal defect of the single crystal.

[0007] As a countermeasure, the following devices have been proposed.

FIG. 5 shows an apparatus proposed by Japanese Patent Publication No. 57-40119 (hereinafter referred to as a first apparatus). This device has an upper flat annular rim 7a projecting from the edge of the crucible, and a connecting portion 7b attached to the annular rim 7a and tapering conically downward from an inner edge. , The inner height of the connecting portion 7b is the depth of the crucible 1
It is characterized by 0.2 to 1.2 times.

FIG. 6 shows an apparatus disclosed in JP-A-64-72984 (hereinafter referred to as a second apparatus). This apparatus extends downward from the junction between the metal chamber 6 and the sub-chamber 6c, is air-tightly joined to the sub-chamber 6c, and coaxially surrounds the growing single crystal 4 with heat.
10 and a doughnut-shaped heat-resistant heat insulator having an outer periphery closely contacting the upper end of the heat-insulating member 12 and substantially matching the outer periphery of the heat-insulating member 12, and having a through hole at the center thereof for substantially fitting the heat-resistant heat-insulating cylinder 10. It is characterized by having a plate 11.

The above-described first and second devices improve the crystal pulling speed due to a radiation heat shielding effect, prevent fine particles of silicon monoxide from dropping into a silicon melt, and further suppress thermal oxidation-induced stacking faults (hereinafter referred to as “defects”) of a crystal substrate. , OSF). However, these devices have a problem in improving the oxide film breakdown voltage characteristics required for highly integrated fine semiconductors.

In addition, there is a problem in that the suppression of the oxygen concentration in the crystal is adversely affected.

[0012] The formation mechanism of a defect that degrades the withstand voltage characteristic of an oxide film has not yet been sufficiently elucidated.

However, during the crystal growth, a defect nucleus is generated in the crystal, which causes a defect in the oxide film breakdown voltage characteristic. The defect nucleus shrinks in a high temperature region after the crystal growth, and grows in a low temperature region. Proceedings of the 39th Spring Meeting of the Japan Society of Applied Physics, 30P-ZD-1
7), it is known that the breakdown voltage characteristics of an oxide film are caused by the thermal history after crystal growth.

In the first apparatus shown in FIG. 5, the internal height of the frusto-conical cylindrical connecting portion 7b disposed around the pulled crystal is as short as 0.2 to 1.2 times the crucible height. Therefore, the crystal immediately after the crystal growth is directly exposed to the atmosphere in the metal chamber kept at a low temperature, so that the crystal is rapidly cooled and the defect nucleus does not shrink, so that the oxide film breakdown voltage characteristic is reduced.

In the second apparatus shown in FIG. 6, a heat-resistant heat-insulating cylinder 10 is provided with a water-cooled metal chamber 6 and a sub-chamber.
Since the inner surface of the heat-resistant heat-insulating cylinder 10 has a low temperature due to heat conduction because it is air-tightly bonded to the bonding portion with 6c, it is rapidly cooled in a high-temperature region immediately after crystal growth.

For this reason, in the crystal immediately after the crystal growth, the defect nucleus does not shrink, and the breakdown voltage characteristic of the oxide film deteriorates.

On the other hand, in order to effectively exert the intrinsic gettering action described above, it is necessary to control the oxygen concentration in the single crystal with a precision of ± 0.75 × 10 ¹⁷ atoms / cm ³ with respect to a target value. However, the oxygen concentration is strongly affected by the flow state of the argon gas.

The flow rate Vg of the argon gas depends on the gas supply pressure Pg, the gas flow rate Qg, the gas passage space sectional area Ag, and the furnace pressure Pf, and is expressed by the following equation (A).
This gas flow velocity Vg is determined not only by the oxygen concentration in the single crystal, but also
It also has a significant effect on the contamination of single crystals from carbon monoxide generated by the reaction of graphite members such as silicon monoxide evaporated from the melt surface and a heater.

Vg = (Qg / Ag) × (Pg / Pf) (A) In the first device shown in FIG. 5, a frusto-conical cylindrical connecting portion 7 b
Since the flat annular rim 7a and the cylindrical tubular member 13 are airtightly connected to each other, all the argon gas flowing from above the pulling chamber is supplied from the inside of the connecting portion 7b to the lower end of the connecting portion 7b and the surface of the molten liquid 5. After passing over the surface of the melt 5, the gas flow 31 flows downward on the inner and outer peripheral surfaces of the heater 2.

As described above, the argon gas flowing from above the pulling chamber is a complicated turbulent flow, and the influence of the upward flow of silicon monoxide evaporating from the surface of the melt 5 on the flow of the argon gas also affects the connection portion 7b. Not uniform in the circumferential direction. for that reason,
The argon gas flowing out from the lower end of the connecting portion 7b does not uniformly flow in the circumferential direction, and the flow rate Vg of the argon gas flowing through the gap between the lower end of the connecting portion 7b and the surface of the melt 5 causes a partial speed difference.

In the first apparatus shown in FIG. 5, when the gas flow rate Vg is increased by increasing the flow rate Qg of the argon gas, the function of discharging silicon monoxide and carbon monoxide is sufficiently exhibited. Therefore, it is possible to prevent them from being mixed into the melt 5. However, since the flow velocity Vg in the gap between the lower end of the connecting portion 7b and the surface of the melt 5 also increases, a partial speed difference in the circumferential direction increases, and the surface temperature of the melt 5 and the convection of the melt 5 increase. This makes it difficult to precisely control the oxygen concentration in the crystal within a desired range with good reproducibility.

If the flow velocity Vg in the gap between the tip of the connecting portion 7b and the surface of the melt 5 increases, the surface of the melt 5 vibrates, and a situation may occur in which dislocation-free single crystals cannot be pulled. On the other hand, when the gas flow rate Vg is reduced by decreasing the flow rate Qg of the argon gas, the difference in the flow rate Vg in the gap between the lower end of the connecting portion 7b and the surface of the melt 5 is also reduced, so that the oxygen concentration control is performed. Sex is improved. But,
As the gas flow rate Vg decreases, the ability to discharge silicon monoxide and carbon monoxide decreases, and the problem arises that silicon monoxide and carbon monoxide that are not properly discharged contaminate the silicon melt 5.

The above problem exists not only in the first device but also in the second device shown in FIG. 6, and is a problem common to conventional devices.

In order to solve the above-mentioned problems in the conventional apparatus, the present applicant forms a temperature distribution appropriately in the pulling direction of the single crystal, avoids mixing of impurities into the single crystal, and reduces the temperature in the crystal. A manufacturing apparatus and a manufacturing method capable of pulling and growing a single crystal having excellent oxide film breakdown voltage characteristics without impairing the precision controllability of oxygen concentration have been proposed (Japanese Patent Application Laid-Open No. 7-277887,
Hereinafter, this is referred to as a prior application).

As shown in FIGS. 7 (a) and 7 (b), the apparatus according to the invention of the prior application is described as follows. An interval between the upper end of the member 7 and the ceiling 6a of the metal chamber 6 for branching the inert gas supplied from above the metal chamber 6 into an inert gas 32 flowing downward inside and outside the member 7. with h _1, a single crystal production apparatus "is supported from the ceiling portion 6a or sidewall 6b top of the metal chamber 6.

According to the apparatus of the prior application, not only can the temperature gradient in the pulling direction of the single crystal be adjusted, but also the branching and merging of the gas flow in the chamber can be appropriately controlled. Therefore, contaminants can be prevented from being mixed into the single crystal, and the oxide film breakdown voltage characteristics of the single crystal substrate can be improved and the oxygen concentration in the crystal can be precisely controlled.

[0027]

SUMMARY OF THE INVENTION An object of the present invention is to provide a new apparatus which can further improve the characteristics of the single crystal to be manufactured and improve the productivity by further improving the apparatus of the prior invention. And to provide a method for producing a single crystal having a small amount of impurities and the oxygen concentration in the crystal being precisely controlled using the apparatus, and having excellent oxide film breakdown voltage characteristics.
It is in.

[0028]

According to the present invention, as shown in FIG. 1, a crucible 1 containing a raw material melt of a single crystal to be grown, a means 2 for heating the melt, and a crucible 1. A single crystal manufacturing apparatus comprising pulling means 9 for growing a single crystal by bringing a seed crystal into contact with the surface of a melt 5 and a metal chamber 6 accommodating the above members. And a method for producing a single crystal by optimally adjusting the flow of an inert gas in a metal chamber using this apparatus.

A heat-resistant and heat-insulating member 7 having a cylindrical shape or a cylindrical shape whose diameter is reduced from above to below.

The heat-resistant and heat-insulating member 7 is configured such that an inert gas supplied from above the metal chamber 6 flows downward inside the member 7 between the upper end and the ceiling 6 a of the metal chamber 6. It is supported on the ceiling 6 a or the upper portion of the side wall 6 b of the metal chamber 6 with an interval h ₁ capable of branching into the active gas 33 and the inert gas 32 flowing downward outside the member 7.

A heat reflecting member 7 e is attached to at least a part of the inner surface of the heat-resistant and heat-insulating member 7.

The heat-resistant and heat-insulating member 7 is desirably made of graphite, and its surface is desirably coded with silicon carbide. The interval between the ceiling portion 6a of the upper end of the member 7 and the metallic vessel 6 (h ₁₎ is preferably in the range of 5 mm to 100 mm, also adjusting the spacing (h ₁₎ in accordance with the operational conditions in the above-mentioned range It is better to have a structure that can be used. Thereby, the flow rate of the inert gas flowing through this interval, that is, the flow rate can be adjusted to a desired range.

The heat reflecting member 7e is made of, for example, a material having a high reflectivity, a high temperature resistance and no contamination of crystals, such as Mo, and has a conical shape as shown in FIG. This is desirably mounted on the lower part of the heat-insulating member 7 as shown in FIG.

[0034]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a single crystal manufacturing apparatus of the present invention and a method of manufacturing a single crystal using the apparatus will be described with reference to the drawings showing an embodiment of the present invention.

FIG. 1 is a longitudinal sectional view passing through the central axis of the apparatus of the present invention. In the figure, reference numeral 1 denotes a crucible, the inside of which is a quartz container 1a.
It has a double structure with a graphite container 1b on the outside, and is installed on the crucible support shaft 1c. The crucible support shaft 1c is capable of not only rotating the crucible but also raising and lowering the crucible.

The water-cooled metal chamber 6 in the figure is a cylindrical vacuum vessel composed of a ceiling 6a and a side wall 6b around a single crystal pulling axis, and the crucible 1 is disposed at the center of the vacuum chamber. A heater 2 is disposed around the periphery of the heater. On the other hand, above the crucible 1, a pulling means 9 is vertically suspended from the center of the ceiling 6a of the metal chamber 6 so as to be rotatable and vertically movable, and a seed crystal 3 is mounted at a lower end thereof. Seed crystal 3 rises while being rotated by pulling means 9, and single crystal 4 grows at the lower end, which is the contact surface with melt 5.

The conical heat-resistant and heat-insulating member 7 does not come into contact with the ceiling 6a of the metal chamber 6 coaxially with the pulling means 9, and an inert gas such as an inert gas, for example, is provided between the upper end of the heat-resistant and heat-insulating member 7 and the ceiling 6a. Argon gas is held at an interval (h ₁ ) so that it can flow, and is arranged around the single crystal pulling area at an interval (h ₂ ) from the surface of the melt 5. FIGS. 3 and 4 show specific examples of the arrangement of such heat-resistant and heat-insulating members 7. FIG.
Shown in

FIG. 3 is a view showing an example in which the heat-resistant and heat-insulating member 7 is held by the support member 21.

FIG. 7A is a longitudinal sectional view of the holding state by the support member 21, and FIG. 7B is a horizontal sectional view taken along the line AA. FIG. 2C is a perspective view of the heat- and heat-insulating member 7. In this example, four square bar-shaped support members 21 are arranged at 90 ° intervals on the ceiling 6a of the metal chamber 6,
The upper end of the heat- and heat-insulating member 7 is held between the support member 21 and the fastening bolt 21a. Accordingly, the upper end of the heat-insulating member 7 does not come into contact with the ceiling 6a, and an interval is provided so that the argon gas branches and flows downward inside and outside the heat-insulating member 7. Hold. The number of the support members 21 is not limited to the above four, and the shape does not need to be limited to a square rod shape.

As shown in FIG. 3C, the heat-resistant and heat-insulating member 7 is provided at its upper end with a holding through hole 7c through which a plurality of the bolts 21a pass. This is for adjusting an interval (the above-mentioned h ₁ ) between the upper end of the heat-resistant and heat-insulating member 7 and the ceiling 6 a by selecting an arbitrary through-hole for holding. Of course, this adjusting means is not limited to the illustrated means.

FIG. 4 is a view showing an example in which the heat-resistant and heat-insulating member 7 is held by the supporting leg members 22. The heat-resistant and heat-insulating member 7 is attached to the upper part of the side wall 6 b of the metal chamber 6. FIG. 2A is a longitudinal sectional view of a support state of the support leg member 22. FIG. 2B is a perspective view of the support leg member 22. The support leg member 22 is attached to an upper end ring 22a. It consists of four supporting legs 22b and a claw 22c at the tip. FIG. 3C is a perspective view of the heat-resistant and heat-insulating member 7 held by the support leg member 22. The protrusion 7d is provided at four locations on the circumference of the upper end surface.

In this example, the support leg 22 is held by fitting the upper end ring 22a of the support leg 22 to a fastening ring 23 provided above the side wall 6b of the metal chamber 6. Next, the claw portion 22c of the support leg member 22 and the projection 7d of the heat-resistant and heat-insulating member 7 are engaged with each other and separated from the ceiling 6a to hold the heat-resistant and heat-insulating member 7. Further, the distance (h ₁ ) between the upper end of the heat-insulating member 7 and the ceiling 6a is adjusted by adjusting the length and angle of the support leg 22b of the support leg member 22. As in the case of FIG. 3, the shape of the support leg member 22 and the number of the support legs 22b are not limited to those illustrated.

As is clear from FIGS. 3 and 4, the structure of the support member may be configured so as not to close the space between the upper end of the heat-insulating member 7 and the ceiling 6a. The distance between the upper end of the member 7 and the ceiling 6a is such that the argon gas supplied from above the metal chamber 6 is branched and flows downward through the area inside the heat-insulating member 7 and the area outside the heat-insulating member 7. It is provided. As long as such a supporting member is used to support the heat-resistant and heat-insulating member 7 from the ceiling 6a or the side wall 6b of the metal chamber 6, the object of the present invention is achieved.

In any of the examples, the heat-insulating member 7 has a cylindrical shape whose diameter is reduced from the top to the bottom.
Desirably, the heat-resistant and heat-insulating member 7 is made of graphite, and its surface is coated with silicon carbide. If the heat-resistant and heat-insulating member 7 is made of graphite, it can be manufactured with high purity, and there is little risk of contamination of the pulled crystal by heavy metals or the like. If the surface is coated with silicon carbide, gas emission from the pores of the graphite member can be prevented, and the reaction between silicon monoxide evaporated from the surface of the melt 5 and the graphite member can be prevented.

As described above, it is necessary to appropriately adjust the temperature gradient of the pulled crystal in order to obtain a single crystal having excellent oxide film breakdown voltage characteristics. In particular, a temperature gradient is required to gradually cool the high temperature region after crystal growth.

In the apparatus of the present invention, the heat- and heat-insulating member 7 is provided in a wide range from the surface of the melt 5 in the crucible to the ceiling 6 a of the metal chamber 6 around the pulling region of the single crystal. And it is attached with an appropriate space between it and the ceiling 6a of the water-cooled metal chamber 6, and is not airtightly joined to the ceiling.

With such a structure, the crystal after the crystal growth is directly exposed to the low-temperature atmosphere in the metal chamber because the internal height of the connecting portion 7b is low as in the apparatus shown in FIG. Nothing. Further, since the temperature drop of the heat-insulating member 7 due to heat conduction is small compared to the case where the heat-insulating cylindrical member is air-tightly joined to the ceiling of the metal chamber as in the apparatus shown in FIG. The inner surface can be kept at a high temperature.

As described above, the slow cooling in the high temperature region after the crystal growth can be achieved by the above-described basic structure of the device of the present invention. However, such a structure has a disadvantage that the temperature gradient (G) at the solid-liquid interface becomes small. That is, the presence of the heat-resistant and heat-insulating member 7 hinders the dissipation of heat at the solid-liquid interface and increases the temperature near the solid-liquid interface, thereby reducing G. If this G is small,
The pulling speed (Vc) of the single crystal must be reduced, which ultimately lowers the productivity of the single crystal.

In order to solve the above problem, in the apparatus of the present invention, a heat reflecting member 7e is attached to a part of the inner surface of the heat-resistant and heat-insulating member 7 as shown in FIG. The heat reflecting member reflects heat radiated from the solid-liquid interface upward, that is, toward a high-temperature region after crystal growth to be gradually cooled. Therefore, the heat reflecting member 7e promotes the dissipation of heat at the solid-liquid interface to increase the temperature gradient (G) at that portion, and at the same time, the upper crystal temperature decreases.
It has the effect of keeping the high temperature range of 1000 to 1200 ° C high and reducing the temperature gradient there.

In order to enhance the above effects, it is desirable that the heat reflection member 7e has a reflectance of 0.5 or more.
Further, the heat reflecting member is not limited to, for example, Mo shown in Examples described later, has a high reflectance, withstands high temperatures,
Any material that does not contaminate the crystal may be used.

As shown in FIG. 2, the shape of the heat reflecting member 7a is desirably a cylindrical shape whose diameter is reduced downward in accordance with the shape of the heat and heat insulating member. The heat reflecting member 7e
Although it should be provided at least on the lower inner surface of the heat-resistant and heat-insulating member 7, it may cover the entire inner surface of the heat-resistant and heat-insulating member 7.

According to the device of the present invention having the above structure,
Promotes heat dissipation at the solid-liquid interface and causes a temperature gradient (G) at that portion
And the upper crystallization temperature is 1000 ~ 1200 ℃
It is possible to gradually cool the single crystal in the high temperature region to improve the oxide film breakdown voltage characteristics. In addition, since the temperature gradient of the crystal at the solid-liquid interface can be increased, the pulling speed can be increased to increase the productivity.

Next, the method for producing a single crystal of the present invention will be described.

As shown in FIG. 1, when the apparatus of the present invention is used, the flow 30 of the argon gas supplied from above the metal chamber 6 depends on the distance between the upper end of the heat-insulating member 7 and the ceiling 6a. It is once branched into a gas flow 33 flowing downward inside the member 7 and a gas flow 32 flowing downward outside the heat- and heat-insulating member 7. Branched gas stream 32 and
33 merges in the outer peripheral region of the crucible 1 to form a gas flow 34,
The gas flows between the crucible 1 and the heater 2 and outside the heater 2, and is discharged from the exhaust port 8 to the outside of the chamber together with silicon monoxide and carbon monoxide. Accordingly, the flow rate of the gas flow 33 is reduced by decreasing the flow rate of the gas flow 33 so that the partial velocity difference generated in the flow of the argon gas between the lower end of the heat-resistant and heat-insulating member 7 and the surface of the melt 5 is reduced. Also, as long as the flow rate of the gas flow 32 flowing downward outside the heat-resistant and heat-insulating member 7 is sufficiently ensured, the flow velocity of the gas flow 34 converging toward the exhaust port 8 can be maintained at a certain value or more. Therefore, the oxygen concentration in the single crystal can be controlled accurately, and silicon monoxide and carbon monoxide can be appropriately discharged.

The distance (h ₁ ) between the upper end of the heat-insulating member 7 and the ceiling 6a is preferably set in the range of 5 mm to 100 mm. h
_{If 1} is less than 5 mm, the gas flow 33 becomes dominant, and the flow of argon gas between the lower end of the heat-resistant and heat-insulating member 7 and the surface of the melt 5 has a large partial velocity difference. A change occurs in the surface temperature and the convection of the melt 5, and it becomes difficult to precisely control the oxygen concentration in the crystal to a desired range. On the other hand, if h ₁ exceeds 100 mm, the cooling rate of the pulled crystal 4 becomes too high due to the influence of the water-cooled metal chamber 6 and the withstand voltage characteristics of the oxide film deteriorate. Further h ₁ is even more desirable to 30mm or less. h
_{If 1} exceeds 30 mm, the gas flow 33 that should flow to the exhaust port 8
Flows backward or stays in the single crystal pulling region, and the evaporated silicon monoxide is condensed in the metal chamber 6 to form the molten liquid 5.
May fall.

The distance (h ₂ ) between the lower end of the heat-insulating member 7 and the surface of the melt 5 is preferably in the range of 10 mm to 50 mm. h ₂
Exceeds 50 mm, the influence of radiant heat from the heater or the melt on the pulled crystal becomes large, and the pulling speed of the crystal must be reduced.

When h ₂ is in the range of ₁₀ to 50 mm, the gas flow of the argon gas between the lower end of the heat-insulating member 7 and the surface of the melt 5 is made uniform, and the effect of shielding the pulled crystal from heat is ensured. Can be.

In order to control the oxygen concentration in the crystal with respect to the target value with an accuracy of, for example, ± 0.75 × 10 ¹⁷ atoms / cm ³ , the flow rate of the argon gas on the surface of the melt 5 is reduced, and It is necessary to minimize a large speed difference. Then, to control reproducibly the gas flow velocity, the distance h ₂ between the distance h ₁ and the heat resistant and heat insulating member 7 the lower end and the surface of the melt 5 in the upper end and the ceiling portion 6a of the heat insulating component 7 , Within the above range.

When producing a single crystal using the apparatus of the present invention, the flow rate and flow rate of the argon gas are properly adjusted according to the single crystal pulling conditions such as the size of the single crystal, the pulling speed, and the required oxygen concentration. It is preferable to set the interval h ₁ and the interval h ₂ in advance so as to manufacture a single crystal.

[0060]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In the manufacturing apparatus of the present invention shown in FIG. 1, a heat-insulating member 7 made of graphite, whose surface is coated with silicon carbide, has a height of 380 mm, an upper end inner diameter of 400 mm,
The lower end was formed in a conical cylindrical shape with an inner diameter of 200 mm and a thickness of 10 mm. A heat reflecting member made of Mo and having a thickness of 2 mm and a reflectance of 0.5 is provided below the heat-insulating member 7 (in a range of 1/3 in the height direction).
7e (shape shown in FIG. 2) was attached.

The heat-resistant and heat-insulating member 7 having the above structure is shown in FIG.
The heat-insulating member 7 held by the supporting member 21 shown in FIG.
The top and the spacing h ₁ between the ceiling portion 6a of the metallic vessel 6 10
and mm, the distance h ₂ between the lower end and the melt 5 surface of the heat resistant and heat insulating member 7 as 30 mm, is disposed substantially coaxially with the pulling shaft 9 of the single crystal.

Separately, as a comparative example, pulling was performed under the same pulling conditions using an apparatus using a heat-resistant and heat-insulating member without the heat reflecting member.

The pulled single crystal 4 is a silicon single crystal having a diameter of 6 inches, the quartz crucible 1a having an inner diameter of 406 mm (16 inches) is used, and the flow rate of argon gas flowing into the metal chamber 6 is 60 l / liter. min condition.

The pulling speed was 1.2 mm / min when the heat reflecting member 7e was attached (Example of the present invention), and 1.1 mm / min when the heat reflecting member 7e was not attached (Comparative Example), and the pulling length was 12 mm.
00 mm.

The single crystal thus pulled up has a dislocation-free single crystal yield,
Evaluations were made on test items such as an OSF conforming rate, an oxide film withstand voltage conforming rate, and an oxygen concentration passing rate. Here, the dislocation-free single crystal yield is
It is represented by the ratio of the weight of the dislocation-free single crystal obtained by cutting and removing dislocations to the weight of the used polycrystalline raw material. OSF non-defective rate is as follows: 780 ℃ × 3Hr and 1000 ℃ × 16
After heat treatment of Hr, selective etching was performed, and those having an OSF defect equal to or less than a reference value (10 / cm ² ) were regarded as non-defective products, and represented by a ratio of the number of non-defective OSF wafers to the total number of wafers.

The oxide film breakdown voltage non-defective rate is evaluated by a voltage ramping method. The gate electrode is made of phosphorus (P) -doped polycrystalline silicon, is a dry oxide film having a film pressure of 250 °, and its area is 8 mm ^2. The quality of a wafer was determined as a non-defective wafer that did not undergo dielectric breakdown even at a reference value (average electric field of 8 Mv / cm) or more, and expressed as a ratio.

Further, the pass rate of oxygen concentration was determined to be ± 0.75 × 10 5 with respect to the standard value among single crystals pulled without dislocation.
Those within the range of ¹⁷ atoms / cm ³ were determined to be acceptable and represented by the ratio of the oxygen concentration pass rate single crystal weight to the dislocation-free single crystal weight.

Table 1 shows the test results.

[0069]

[Table 1]

As shown in Table 1, the silicon single crystal produced by the method of the present invention using the apparatus of the present invention gave better results for all the test items than those produced by the method of the comparative example. Especially in the oxide film breakdown voltage
A 10% improvement has been obtained. In addition, the pulling speed of the present invention example was 1.2 mm / min compared to 1.1 mm / min of the comparative example,
A 1.1-fold improvement in productivity has also been obtained.

[0071]

According to the present invention, the temperature gradient in the pulling direction of the single crystal can be appropriately adjusted, and the branching and merging of the gas flow in the chamber can be appropriately controlled. Thus, contamination of the single crystal with contaminants can be avoided, and the oxide film breakdown voltage characteristics of the single crystal substrate can be improved and the oxygen concentration in the crystal can be precisely controlled. In addition, the pulling speed of the single crystal can be increased, and a high-quality single crystal can be manufactured with high productivity.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing a single crystal manufacturing apparatus of the present invention.

FIGS. 2A and 2B are a longitudinal sectional view and a perspective view showing an example of the shape of a heat reflecting member, and a longitudinal sectional view showing a state where the heat reflecting member is attached to a heat-insulating member.

3A and 3B are diagrams showing an example of a holding state of a heat- and heat-insulating member, wherein FIG. 3A is a longitudinal sectional view, FIG. 3B is a horizontal sectional view, and FIG. is there.

4A and 4B are diagrams showing another example of a holding state of the heat- and heat-insulating member, wherein FIG. 4A is a longitudinal sectional view, FIG.
(C) is a perspective view of the heat-resistant and heat-insulating member held.

FIG. 5 is a longitudinal sectional view showing an example of a conventional single crystal manufacturing apparatus.

FIG. 6 is a longitudinal sectional view showing another example of a conventional single crystal manufacturing apparatus.

FIG. 7 is a longitudinal sectional view showing a single crystal manufacturing apparatus proposed earlier by the present application.

FIG. 8 is a schematic cross-sectional view showing an embodiment of the Czochralski method.

[Explanation of symbols]

1 ... crucible, 1a ... quartz container, 1b ... graphite container, 1c
... crucible support shaft 2 ... heater, 3 ... seed crystal, 4 ... pulled crystal, 5 ...
Melt 6: metal chamber, 6a: ceiling of chamber, 6b: side wall of chamber 6c: sub-chamber 7: heat-resistant and heat-insulating member, 7a: annular rim, 7b: connecting part, 7c ...
Through hole, 7d Projection 7e Heat reflection member 8 Outlet, 9 Pulling means, 10 Heat-resistant insulating cylinder, 11
… Heat-resistant heat-insulating plate 12… Insulation member, 13… Cylindrical tube member 21… Support member, 21a… Tightening bolt 22… Support leg material, 22a… Top ring, 22b… Support leg, 22c
... claw 23 ... fastening ring, 30, 31, 32, 33, 34 ... gas flow

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁶ , DB name) C30B 1/00-35/00

Claims (2)

(57) [Claims] 1. A crucible containing a single crystal raw material melt to be grown, a means for heating the melt, and a pulling means for growing a single crystal by bringing a seed crystal into contact with the surface of the melt in the crucible. And a metal chamber for accommodating each of the above members, wherein the single crystal manufacturing apparatus has the following features. A heat-resistant and heat-insulating member having a cylindrical shape or a cylindrical shape whose diameter is reduced from above to below. The heat-resistant and heat-insulating member is configured such that an inert gas supplied from above the metal chamber between an upper end thereof and a ceiling portion of the metal chamber flows downward through the inside of the heat-resistant and heat-insulating member. It is supported on the ceiling or the upper part of the side wall of the metal chamber with an interval capable of branching to the inert gas flowing down the outside of the heat insulating member. A heat reflecting member is attached to at least a part of the inner surface of the heat-insulating member. 2. A crucible for accommodating a single crystal raw material melt to be grown, means for heating the melt, and pulling means for growing a single crystal by bringing a seed crystal into contact with the surface of the melt in the crucible. And a single crystal manufacturing method using a single crystal manufacturing apparatus having a metal chamber for accommodating each of the above members, wherein the diameter of the single crystal is reduced from a cylinder surrounding the pulling region of the single crystal or downward from above. A heat-resistant and heat-insulating member having a tubular shape and a heat reflection member attached to at least a part of the inner surface at a lower portion thereof is disposed above the melt in the crucible, and the member and a ceiling portion of the metal chamber are provided. An inert gas supplied from above the metal chamber is provided between the metal gas chamber and the inert gas flowing downward from the inside of the member, and the external gas from the outside of the member is directed downward. Flowing Mixture was allowed to branch to the active gas, the method for producing a single crystal, characterized in that for combining the inert gas is branched.