KR20060098417A - Growing method of silicon single crystal and apparatus for growing the same - Google Patents

Abstract

The present invention relates to a technique for producing a high quality silicon single crystal at a high growth rate. In the present invention, a method for growing a silicon single crystal by the Czochralski method, wherein the temperature gradient of the silicon melt is measured along an axis parallel to the radial direction of the single crystal. When the measured maximum temperature gradient is ΔTmax and the minimum temperature gradient is ΔTmin, a silicon single crystal growth method of growing a silicon single crystal under conditions satisfying {(ΔTmax−ΔTmin) / ΔTmin} × 100 ≦ 10 is provided.

Silicone, point defect, melt, temperature

Description

Growing method of silicon single crystal and apparatus for growing the same

1 is a cross-sectional view showing a process of growing a silicon single crystal by the Czochralski method and a temperature gradient profile of a melt measured along an axis parallel to the radial direction of the single crystal ingot according to one embodiment of the present invention.

2 is a cross-sectional view showing a process of growing a silicon single crystal by the Czochralski method and a temperature profile of the melt measured along an axis parallel to the longitudinal direction of the single crystal ingot according to one embodiment of the present invention.

3 is a graph showing the temperature difference ΔTr of the melt from the center position to the crucible wall in the radial direction at 1/5 the silicon melt depth by the crucible rotation speed.

Fig. 4 is a graph showing the growth rate of high quality single crystal with respect to Ln [Vs / Vc], which is a log value obtained by the rotational speed Vc of the crucible and the rotational speed Vs of the silicon single crystal.

5 is a cross-sectional view showing the growth of a silicon single crystal in a state in which a magnetic field is applied according to the present invention.

The present invention relates to a method for growing a high quality silicon single crystal, and more particularly, to grow a high quality silicon single crystal ingot by controlling the temperature distribution of the silicon melt when growing the silicon single crystal by the Czochralski method. An apparatus and a silicon wafer manufactured therefrom.

In the related art, in order to grow a high quality silicon single crystal ingot capable of increasing semiconductor device yield, the high temperature region temperature distribution of the single crystal ingot after crystallization is controlled. This is to control stress induced by shrinkage due to cooling after crystallization or to control the behavior of point defects generated during solidification.

In general, in the method of growing a silicon single crystal ingot according to the Czochralski method, polycrystalline silicon is loaded into a quartz crucible and melted polycrystalline silicon with heat radiated from a heater to form a silicon melt, and then a silicon single crystal ingot from the surface of the silicon melt. To grow.

When growing a silicon single crystal ingot, the crucible is raised while rotating the shaft supporting the crucible so that the solid-liquid interface maintains the same height, and the silicon single crystal ingot is about the same axis as the rotation axis of the crucible in a direction opposite to the rotation direction of the crucible. While rotating, pull up.

In addition, in order to facilitate silicon single crystal ingot growth, an inert gas such as argon (Ar) gas is introduced into the upper portion of the ingot growth apparatus, and a method of discharging the lower portion of the ingot growth apparatus is widely used.

In the conventional silicon single crystal ingot manufacturing method, a heat shield and a water cooling tube were installed to control the temperature gradient of the growing silicon single crystal ingot. Conventional techniques for controlling the temperature gradient of a silicon single crystal ingot using a heat shield and the like include Korean Patent Registration No. 374703, Korean Patent Application No. 2000-0071000, US Patent Registration No. 6,527,859, and the like.

However, only the temperature gradient control of such silicon single crystal ingot has a limitation in producing high quality silicon single crystal ingot and silicon wafer with low point defect concentration.

In particular, if a semiconductor device is manufactured using a silicon wafer manufactured according to the conventional method, micro precipitates are formed from point defects through several heat treatments during the device manufacturing process, resulting in poor device yield. There was a problem of this deterioration.

Meanwhile, as described in Korean Patent Application Nos. 1999-7009261, 1999-7009307, and 1999-7009309, the vertical temperature gradient G ₀ of a crystal has a form of G ₀ = c + ax ² . As a result, the concentration of vacancy increases from the outer circumference of the wafer toward the center, while the interstitial concentration tends to decrease. If sufficient out-diffusion does not occur near the outer periphery of the wafer, crystal defects of interstitial characteristics such as LDP will appear, so crystal growth usually occurs at a high concentration of bacony at the center. Therefore, vacancy concentrations much higher than equilibrium concentrations are likely to cause crystalline defects (eg, voids, oxidation induced stacking faults (OiSF)) at the center of the wafer. Even if the oxidized lamination defect region is controlled, minute precipitation defects, which are latent from several heat treatments in the semiconductor process, may occur.

Other conventional techniques for controlling the temperature distribution of silicon single crystal ingots to produce high quality silicon single crystals include the following. In Japanese Patent Application No. 2-119891, the lattice defect of silicon single crystal due to strain of solidification is reduced by controlling the temperature distribution of the center and the outer circumference of silicon single crystal ingot by adopting hot zone of high temperature region during single crystal cooling. In particular, here, the cooling sleeve increases the solidification rate in the single crystal growth direction and reduces the lattice defects. Also, Japanese Patent Application No. 7-158458 attempted to control the temperature distribution and crystal pulling rate in the crystal. Japanese Patent Application No. 7-66074 tried to control the defect density by improving the hot zone and controlling the cooling rate. Japanese Patent Application Laid-Open No. 4-17542 and Korean Patent Application No. 1999-7009309 (US 60 / 041,845) attempt to suppress crystal defect formation by spreading point defects by changing the hot zone and controlling the cooling rate. Korean application 2002-0021524 claims to improve the high quality single crystal productivity by improving the heat shield and water cooling tube. In Japanese Patent Application No. 5-61924, the crystalline defects are not formed in the silicon single crystal ingot by taking advantage of the hysteresis of the region where crystal defects occur, such as oxygen organic defect (OSF) or oxygen precipitation defect, by periodically changing the growth rate of the crystal. It was not.

However, these prior arts have the following problems because they are based on solid state reactions. First, there are many limitations in achieving the goal of high quality silicon single crystals. For example, Korean application 1999-7009309 (US 60 / 041,845) attempts to reduce the concentration of point defects by sufficiently diffusing supersaturated point defects in a high temperature region before they grow into crystal defects, but the required temperature holding time is even longer than 16 hours. Therefore, there is a problem that is theoretically possible but not practically applicable.

Second, in most cases, there is no practical effect. Impression of crystals in the same way as proposed by Japanese Patent Application No. 5-61924 and Eidenzon et al. (Defect-free Silicon Crystals Grown by the Czochralski Technique, Inorganic Materials, Vol. 33, No. 3, 1997, pp.272-279). The growth of 200 mm silicon single crystal ingots with periodic changes in speed resulted in the failure to achieve the desired high quality, but only caused process instability.

Third, the invention based on the solid state reaction theory cannot achieve high productivity. Korean application 2001-7006403 designed the optimal heat shield and water cooling tube as much as possible, but showed a low productivity with a pulling speed of about 0.4 mm / min to obtain a high quality single crystal.

Another conventional method for obtaining high quality silicon single crystals is to control the solid-liquid interface (crystal growth interface). Korean application 1998-026790 and US Pat. No. 6,458,204 define the form of a solid-liquid interface for obtaining high quality silicon single crystals. However, in Korean application 1999-7009309, a sufficient high quality single crystal was not obtained even in the form of the solid-liquid interface claimed by the above inventions.

In addition, in the above-described conventional methods, the yield of obtaining the desired high quality single crystal was low.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems, and an object thereof is to provide a method and apparatus for producing a high quality silicon single crystal in which the point defect concentration is extremely controlled so as not to cause defects even in actual device manufacturing. will be.

Another object of the present invention is to provide a high quality, high quality silicon single crystal growth method.

It is still another object of the present invention to provide a high quality silicon single crystal growth method with high acquisition yield.

In order to achieve the above technical problem, in the present invention, when the silicon single crystal is grown by the Czochralski method, the occurrence of point defects is minimized by controlling the temperature distribution of the silicon melt to grow a high quality silicon single crystal ingot.

That is, in the present invention, in the method of growing a silicon single crystal by the Czochralski method, when the temperature gradient of the silicon melt is measured along an axis parallel to the radial direction of the single crystal, the measured maximum temperature gradient is called ΔTmax and the minimum temperature. When the slope is ΔTmin, a silicon single crystal growth method is provided in which a silicon single crystal is grown under a condition satisfying {(ΔTmax−ΔTmin) / ΔTmin} × 100 ≦ 10.

Here, it is preferable that {(ΔTmax-ΔTmin) / ΔTmin} × 100 satisfies {(ΔTmax-ΔTmin) / ΔTmin} × 100 ≦ 5, more preferably the {(ΔTmax-ΔTmin) / ΔTmin} X100 satisfies {(ΔTmax-ΔTmin) / ΔTmin} × 100 ≦ 3, and most preferably the {(ΔTmax-ΔTmin) / ΔTmin} × 100 is {(ΔTmax-ΔTmin) / ΔTmin} × 100 ≤ 1 is satisfied.

At this time, the temperature gradient is a vertical instantaneous temperature gradient of the melt.

In addition, while satisfying the above equation, when the temperature of the silicon melt is measured along an axis parallel to the longitudinal direction of the single crystal, the temperature of the melt gradually increases to reach the peak as the temperature increases from the interface between the melt and the single crystal. It is preferable to grow a silicon single crystal so as to satisfy the condition of falling and keeping the rising melt temperature slope larger than the falling melt temperature slope.

When measuring the temperature gradient of the silicon melt along an axis parallel to the radial direction of the single crystal, it is preferable in the melt from the solid-liquid interface to the height having the highest point temperature.

When the temperature of the silicon melt is measured along an axis parallel to the longitudinal direction of the single crystal, the axis preferably passes through the center of the silicon single crystal.

The peak may be present at 1/5 to 2/3 points from the surface of the melt relative to the total depth of the silicone melt, preferably from 1/3 to 1/2 point from the surface of the melt relative to the total depth of the silicone melt. May exist in

When the crucible holding the silicon melt has a rotational speed of Vc and a silicon single crystal having a rotational speed of Vs, it is preferable to grow a silicon single crystal under conditions satisfying 3 ≦ Ln [Vs / Vc] ≦ 5.

At this time, the Vc preferably satisfies Vc ≦ 2 rpm, more preferably the Vc satisfies Vc ≦ 1 rpm, and most preferably the Vc satisfies Vc ≦ 0.6 rpm.

In addition, it is preferable to grow a silicon single crystal in a state in which a magnetic field is applied to the silicon melt. In this case, a magnetic field in a vertical direction or a horizontal direction with respect to the longitudinal direction of the single crystal is applied to the silicon melt, or in the form of a cusp. Magnetic field can be applied.

In addition, a heater is provided on the side of the silicon melt, and the silicon single crystal is formed in a state in which the calorific value of the portion corresponding to 1/5 to 2/3 points from the surface of the melt is increased relative to the periphery of the silicon melt in the heater. Can grow.

The magnetic field can promote the flow of heat from the closest portion with the heater toward the center of the solid-liquid interface to the high temperature region of the melt.

In addition, the present invention is a device for growing a silicon single crystal by the Czochralski method, which is installed inside the chamber, inside the chamber, and installed on the side of the crucible containing the silicon melt, the crucible to heat the silicon melt, Installed on the side of the crucible, a heater that raises the amount of heat generated from the surface of the melt corresponding to 1/5 to 2/3 from the surface of the melt, and the silicon single crystal grown from the silicon melt. To provide a silicon single crystal growth apparatus comprising a magnet for applying a magnetic field to the silicon melt.

The growth device may further comprise a heat shield disposed between the silicon single crystal ingot and the crucible so as to surround the silicon single crystal ingot, and blocking the heat radiated from the ingot, and attached to the closest portion of the heat shield to the silicon single crystal ingot. And a cylindrical heat shield surrounding the silicon single crystal ingot.

Hereinafter, the present invention will be described in detail.

The present invention is directed to the fact that growing high quality silicon single crystal ingots with minimal point defects in growing solid silicon single crystals from a silicon melt is not achieved by only controlling the temperature gradient of the single crystal ingot and controlling the shape of the solid-liquid interface. Starting from the recognition, we focused on the fact that there is a more decisive factor for the growth of high quality silicon single crystal ingots.

In the present invention, in order to overcome the limitations of the solid phase reaction occurring after crystallization, the fluid state of the liquid phase before solidification was thoroughly analyzed, and as a result, the temperature distribution of the melt was found to be very important.

In general, crystal growth is achieved by moving a growth unit in the form of atoms or molecules into a crystal growth interface or a metastable region and adhering to the interface.As the temperature gradient in the silicon melt increases, the crystal growth unit in the fluid state becomes a crystal growth interface or quasi-state. The driving force to move to the stable area is increased.

The crystal growth interface, also referred to as crystallization interface or solid-liquid interface, is an interface where a solid silicon single crystal ingot meets a liquid silicon melt. The metastable region refers to a region in which the liquid silicon melt is just before crystallization but is crystalline but incomplete.

Therefore, when the temperature gradient in the silicon melt is large, the participation of crystal growth in the growth unit increases, so that when the pulling rate of the crystal is not high enough, excess atoms are crystallized. As a result, the silicon single crystal ingot has a self-interstitial rich characteristic. Will have On the contrary, when the temperature gradient in the silicon melt is low, there are not enough atoms to crystallize, and thus the pulling rate of the high crystal creates a silicon single crystal ingot having vacancy rich characteristics.

1 is a cross-sectional view showing a process of growing a silicon single crystal by the Czochralski method according to an embodiment of the present invention. As shown in FIG. 1, the apparatus for manufacturing a silicon single crystal ingot according to an embodiment of the present invention includes a chamber 10, and growth of the silicon single crystal ingot is performed in the chamber 10.

The quartz crucible 20 containing the silicon melt SM is installed in the chamber 10, and the crucible support 25 made of graphite is installed outside the quartz crucible 20 so as to surround the quartz crucible 20. do.

The crucible support 25 is fixedly installed on the rotating shaft 30, which is rotated by a driving means (not shown) to raise the crucible 25 while rotating the quartz-liquid interface to have the same height. Keep it. The crucible support 25 is surrounded by a cylindrical heater 40 at predetermined intervals, and the heater 40 is surrounded by a thermos 45.

That is, the heater 40 is installed on the side of the crucible 25 to melt a high-purity polysilicon mass loaded in the quartz crucible 20 to form a silicon melt SM, and the heat insulating cylinder 45 is the heater 40. The heat emitted from the to prevent the diffusion to the wall of the chamber 10 to improve the thermal efficiency.

In the upper part of the chamber 10, a pulling means (not shown) for winding and pulling a cable is provided. The lower part of the cable 10 is in contact with the silicon melt SM in the quartz crucible 20 and pulled up to form a single crystal ingot ( A seed crystal for growing IG) is installed. The pulling means rotates while pulling up the cable during the growth of the single crystal ingot IG, wherein the silicon single crystal ingot IG is rotated about the same axis as the rotation axis 30 of the crucible 20. Rotate in the opposite direction to the direction of pulling up.

In the upper portion of the chamber 10, an inert gas such as argon (Ar), neon (Ne), and nitrogen (N) is supplied to the grown single crystal ingot (IG) and the silicon melt (SM). Discharge through the bottom of the chamber (10).

Between the silicon single crystal ingot (IG) and the crucible 20 can be installed a heat shield 50 to surround the ingot (IG) to block the heat radiated from the ingot, in the heat shield 50 ingot (IG) and The closest portion of the cylindrical heat shield 60 is attached to the installation to further block the heat flow can be preserved heat.

In the present invention, the temperature of the silicon melt SM is controlled to be uniform in the radial direction of the single crystal IG.

To illustrate this in more detail, FIG. 1 shows an isotherm in the silicon melt SM and also shows the temperature gradient profile of the melt measured along an imaginary axis parallel to the radial direction of the single crystal ingot.

In general, when looking at the temperature of the silicon melt (SM), the liquid-liquid interface at which the crystal growth occurs, showing the highest melt temperature (indicated by the T _P region in Figure 1) in the side portion of the crucible closest to the heater 40, the heat source Shows the lowest melt temperature, which is the solidification temperature in the part.

When measuring the temperature gradient of the silicon melt SM along an axis parallel to the radial direction of the single crystal IG, this temperature gradient is a vertical instantaneous temperature gradient, and is preferably measured in the melt located below the single crystal IG. Do.

If the maximum value of the measured temperature gradient is called ΔTmax and the minimum value is ΔTmin, the silicon single crystal is grown under the conditions satisfying Equation 1 below.

{(ΔTmax-ΔTmin) / ΔTmin} × 100 ≤ 10

Equation 1 above means that the difference between the maximum temperature gradient ΔTmax and the minimum temperature gradient ΔTmax is controlled to be 10% or less with respect to the minimum temperature gradient. In this case, the content is preferably 5% or less, more preferably 3% or less, and even more preferably 1% or less.

If the temperature of the silicon melt SM becomes uneven in the radial direction of the single crystal IG such that the difference between the maximum temperature gradient ΔTmax and the minimum temperature gradient ΔTmax exceeds 10% with respect to the minimum temperature gradient, in the present invention, The high quality silicon single crystal to be presented cannot be obtained. Since the temperature of the silicon melt may change periodically due to the influence of melt convection, the measured temperature is preferably taken as an average value.

In addition, in the present invention, there is a high temperature region (indicated by the T _H region in FIG. 1) having a relatively high temperature inside the melt, especially the temperature gradient of the upper portion of the high temperature region T _H and the temperature of the lower portion. Control the slope

To illustrate this in more detail, FIG. 2 also shows the temperature profile of the melt measured along the axis X parallel to the longitudinal direction of the single crystal ingot.

When the temperature of the silicon melt SM is measured along the axis X parallel to the longitudinal direction of the silicon single crystal ingot IG, the temperature of the melt SM gradually increases as it moves away from the solid-liquid interface to the ingot IG. The highest point (H) is reached and then descends gradually toward the bottom of the melt (SM), which is the furthest point from the highest point (H) to the ingot (IG).

At this time, the rising melt temperature gradient ΔTi from the solid-liquid interface to the highest point H is greater than the falling temperature gradient ΔTd from the highest point H to the melt bottom, that is, ΔTi> ΔTd. While maintaining, it is preferable to grow a single crystal ingot. Here, it is preferable that the axis | shaft X which becomes a reference | standard which displays a temperature measuring position is a central axis which penetrates the center of a single crystal ingot.

At this time, the highest point (H) is preferably present at 1/5 to 2/3 from the surface of the melt (SM) with respect to the total depth of the silicon melt (SM), more preferably 1/3 to 1 May exist at point / 2.

It is more preferable to grow the single crystal ingot while satisfying the above expression (1) and maintaining the above condition of ΔTi> ΔTd.

In this case, when the temperature gradient of the silicon melt, measured in Equation 1, is measured along the axis parallel to the radial direction of the single crystal, the melt from the solid-liquid interface at which crystal growth occurs to the height (D ₁ ) having the highest temperature (H) temperature is used. It is preferable to measure.

The temperature gradient profile shown in FIG. 1 is measured at 1/5 point from the surface of the melt (SM).

On the other hand, in the present invention, it was found that the melt temperature distribution in the single crystal radial direction is related to the rotational speed of the crucible 20 containing the silicon melt SM. When the crucible containing the silicon melt is rotated, the silicon melt is subjected to centrifugal force. At this time, the centrifugal force (F) received by the unit volume of the melt is expressed as F = mrω ² . Where m is the mass of the unit volume of the melt, r is the distance from the central axis, and ω is the angular velocity experienced by the unit volume of the melt. In addition to centrifugal forces, frictional forces, etc., will not be considered due to the relatively low viscosity of the silicon melt.

That is, as the position of the melt changes radially from the single crystal center position toward the outer circumferential portion, the centrifugal force (F) received by the unit volume of the melt increases linearly, and the centrifugal force (F) increases in proportion to the square of the crucible rotation speed. do.

FIG. 3 is a graph showing the temperature difference ΔTr of the melt from the center position to the crucible wall radially from the center position (from the surface) at the 1/5 point of the silicon melt by the crucible rotational speed, that is, ω the _three curves in the down to ω ₁ curve melt temperature distribution in the radial direction to decrease the melt temperature difference (ΔTr) in the radial direction can be seen so as to be uniformly improved.

Therefore, in order to make the temperature of the silicon melt uniform in the radial direction of the single crystal, the crucible rotation speed should be as low as possible, for example, 2 rpm or less, preferably 1 rpm or less, and more preferably 0.6 rpm or less.

In addition, in order to manufacture high quality single crystal with high productivity, the operating range of the single crystal (IG) rotation speed should be determined in consideration of the rotation speed of the crucible 20. Fig. 4 is a graph showing the growth rate of single crystals against Ln [Vs / Vc], which is a log value obtained by the rotational speed Vc of the crucible and the rotational speed Vs of the silicon single crystal. In the graph of FIG. 4, Vp means a growth rate at which high-quality single crystals are implemented according to the present invention, and Vo is a growth rate according to the prior art.

As the Ln [Vs / Vc] value increases from the graph of FIG. 4, it can be seen that the growth rate of high quality single crystal is increased and then decreases again after a certain period. This is because, as in Korean Patent Application No. 2003-0080998, which the inventors have previously filed, when the single crystal rotation speed becomes too large compared to the low crucible rotation speed, the temperature of the hot zone decreases due to the rise of the cold melt at the bottom of the crucible, and thus This is because the vertical temperature gradient decreases. In addition, when setting the value of Ln [Vs / Vc], abnormal growth of crystals may occur if the melt temperature gradient in the single crystal radial direction near the triple point where single crystal (solid)-melt (liquid)-atmosphere (gas) meets becomes too small. It is desirable to avoid such values as they may be. Through these results, in the present invention, when the rotation speed of the crucible is Vc and the rotation speed of the silicon single crystal is Vs, the silicon single crystal is grown under the condition that the following Equation 2 is satisfied.

3 ≤ Ln [Vs / Vc] ≤ 5

As another method, the present invention uses a magnetic field to make the temperature of the silicon melt more uniform in the radial direction of the single crystal. That is, in the present invention, a silicon single crystal is grown while a magnetic field is applied to the silicon melt. In this case, as the magnetic field, a magnetic field in a vertical direction or a horizontal direction with respect to the longitudinal direction of the single crystal may be applied, or a magnetic field having a CUSP shape may be applied.

5 is a cross-sectional view illustrating growth of a silicon single crystal in a state in which a cusp-shaped magnetic field is applied, and FIG. 4 illustrates a magnetic field profile. The magnetic field controls the convection of the silicon melt. More specifically, it inhibits the flow of the melt in a direction perpendicular to the lines of magnetic force, thus affecting the flow of heat. Thus, the magnetic field applied to the silicon melt promotes the flow of heat from the closest portion T _P with the heater to the center of the solid-liquid interface to the high temperature region T _H of the melt.

That is, since the magnetic field helps to transfer heat from the highest temperature region T _P to the high temperature region T _H while minimizing heat loss, the temperature difference between the solid-liquid interface and the high temperature region T _H , that is, the rising melt As temperature gradients increase, high-quality crystal growth rates may increase.

Further, in the present invention, the heater can be improved in order to make the position of the peak H and the temperature gradient in the melt SM as described above. For example, in the heater 40 provided on the side of the silicon melt, the silicon single crystal in a state in which the calorific value of the portion corresponding to 1/5 to 2/3 from the surface of the melt is increased relative to the periphery with respect to the total depth of the silicon melt. Ingots can be grown.

More preferably, in the heater, the calorific value of the portion corresponding to 1/3 to 1/2 point from the surface of the melt with respect to the total depth of the silicon melt can be increased compared to the surroundings.

For example, in the case of a heater using Joule's heat generated by passing a current through a resistance wire, a portion corresponding to 1/5 to 2/3 points, more preferably 1/3 to 1/2 points from the surface of the melt It is possible to increase the resistance of the corresponding part. As such, in order to increase the resistance of a specific part of the heater, the resistance is proportional to the specific resistance and the length and is inversely proportional to the cross-sectional area, so that the cross-sectional area is narrowed or a high specific resistance heater material is used.

As described above, as a result of optimizing the temperature distribution of the melt, it was possible to easily obtain a high quality single crystal that eliminated various crystal defects, and it was confirmed that the growth rate realized was greatly improved.

This phenomenon is due to the increase in the melting temperature gradient from the solid-liquid interface to the highest point, which increases the driving force for the growth of atoms or molecules to move to the crystal growth interface, thereby minimizing defects such as bacon and interstitial. The high quality crystal growth rate, that is, the pulling rate of the crystal, can be improved.

By controlling the improvement of the heater as described above, the application of the magnetic field, the rotation speed of the crucible and the single crystal, the so-called 'channel effect' causes the temperature distribution of the silicon melt to be described in the single crystal radial direction and the single crystal length direction. Optimized as conditions.

As shown in FIG. 4, 'channel effect' means heat transfer while minimizing heat loss along the virtual channel 100 from the highest temperature region of the melt toward the high temperature region. In this way, the channel effect not only increases the melt temperature gradient from the solid-liquid interface to the high temperature region, that is, the rising melt temperature gradient, but also reduces the temperature of the crucible bottom to the maximum because the temperature of the crucible bottom is relatively low. Will be.

In the present invention, by controlling the occurrence of point defects such as bacon and interstitial by the above-described method, dislocation defects (edge, screw, loop type dislocations) and stacking defects which are growth defects (stacking fault), defects such as void (vaid aggregate) is suppressed.

Thus, the silicon single crystal ingot grown using the apparatus and method described above has a low point defect concentration contained therein of 10 ¹⁰ to 10 ¹² pieces / cm ³ . This degree of point defect concentration is the vacancy threshold, which is the minimum concentration of vacancy that can form micro precipitates by heat treatment when ingots are subsequently fabricated into wafers and semiconductor devices are fabricated from the wafers. Corresponds to saturation concentration.

Recent advances in silicon wafer fabrication technology have resulted in point defect concentrations as low as 10 ¹¹ to 10 ¹³ / cm ³ , thus achieving defect-free wafer levels in as-grown conditions. However, even as-grown defect-free wafers having a point defect concentration of about 10 ¹¹ to 10 ¹³ pieces / cm ³ , secondary defects such as microprecipitation defects due to heat treatment are not produced during the fabrication of the actual semiconductor device from the wafer. It is occurring.

Thus, the present invention provides a wafer having a lower point defect concentration so that such secondary defects do not occur. That is, a wafer having a high point defect concentration having a level equal to or less than the bacony critical saturation concentration, which is the minimum bacony concentration capable of forming microprecipitation defects by heat treatment, is manufactured.

At this time, the standard heat treatment conditions for defining the critical saturation concentration in bacon are the first heat treatment performed at 700-800 ° C. for 5-7 hours and the second heat treatment performed at 1000-1100 ° C. for 14-18 hours. It includes. Further, the microprecipitation defects are smaller than or equal to 0.3 mu m and formed within a depth greater than or equal to at least 1 mu m from the wafer surface.

As described above, the silicon wafer of the present invention having a point defect concentration of 10 ¹⁰ to 10 ¹² pcs / cm ³ does not produce secondary defects such as microprecipitation defects through any device process.

In the past, the center of the wafer was the dominant region of baconsea and the outer region of the wafer was the interstitial dominant region. Thus, in the present invention, the center of the silicon ingot and the wafer may be an interstitial dominant region, and the outer part of the center may be a vacancy dominant region. In addition, a balanced region in which the interstitial concentration and the baconic concentration are balanced cannot be identified as either an interstitial dominant or baconsie dominant. In addition, since the present invention is based on the fluid phenomenon, the interstitial predominant regions and the baconsea predominant regions do not necessarily appear symmetrically about the central axis in the ingot longitudinal direction, but there are no problems in securing high quality single crystals and silicon wafers. Does not occur. That is, in the silicon wafer manufactured according to the present invention, the interstitial dominant region and the vacancy dominant region may be asymmetric with respect to the center of the wafer.

In addition, the silicon single crystal ingots and wafers produced according to the present invention have a uniform distribution of point defects. For example, when the point defect concentration is measured in an area within 90% of the radius from the center of the ingot and the wafer, the point defect concentration having the lowest difference between the highest point defect concentration (Cmax) and the lowest point defect concentration (Cmin) ( The distribution of point defects is uniform to the extent that it is within 10% with respect to Cmin, ie, satisfy | fills the conditions which are (Cmax-Cmin) / Cminx100 <= (10)%.

On the other hand, two types of convection are largely distributed in the melt. That is, the convection distribution of the melt rises to the surface of the melt SM along the bottom and sidewall portions of the crucible and circulates toward the single crystal along the surface of the melt SM and the lower portion of the single crystal along the inner slope of the outer circumferential region. It is divided into an inner region that circulates in the proximal portion.

Preferred convection distribution of the melt in the present invention is described in detail in patent application 2003-0080998, to which the inventors have filed. This makes the quality of the single crystal more uniform in the radial direction.

As described above, according to the present invention, by controlling the temperature distribution of the silicon melt to the specific conditions presented in the present invention, it is possible to grow a high quality silicon single crystal ingot, and also due to the high growth rate, high quality silicon single crystal with high productivity It is effective in providing a method for growing an ingot.

In addition, the present invention has the effect of providing a high-quality silicon single crystal ingot and silicon wafer having a low point defect concentration at a level where secondary defects such as microprecipitation defects are not generated by heat treatment in the actual device manufacturing process.

Using a wafer processed from such a high quality single crystal as a substrate has an effect of improving the yield of an electronic device.

Claims (25)

In the method of growing a silicon single crystal by the Czochralski method, When the temperature gradient of the silicon melt is measured along an axis parallel to the radial direction of the single crystal, the measured maximum temperature gradient is ΔTmax and the minimum temperature gradient is ΔTmin. How to grow. {(ΔTmax-ΔTmin) / ΔTmin} × 100 ≤ 10 The method of claim 1, The {(ΔTmax-ΔTmin) / ΔTmin} × 100 is, {(ΔTmax-ΔTmin) / ΔTmin} × 100 ≦ 5, wherein the silicon single crystal growth method is satisfied. The method of claim 1, The {(ΔTmax-ΔTmin) / ΔTmin} × 100 is, {(ΔTmax-ΔTmin) / ΔTmin} × 100 ≦ 3, wherein the silicon single crystal growth method is satisfied. The method of claim 1, The {(ΔTmax-ΔTmin) / ΔTmin} × 100 is, A method for growing a single crystal of silicon, characterized by satisfying {(ΔTmax−ΔTmin) / ΔTmin} × 100 ≦ 1. The method of claim 1, Wherein said temperature gradient is a vertical instantaneous temperature gradient of said melt. The method of claim 1, While satisfying the above formula, when the temperature of the silicon melt was measured along an axis parallel to the longitudinal direction of the single crystal, the temperature of the melt gradually increased and reached the highest point as it moved away from the interface between the melt and the single crystal. And the silicon single crystal is grown so as to satisfy the condition that the rising melt temperature slope remains larger than the falling melt temperature slope. The method of claim 6, And the temperature gradient of the silicon melt is measured in the melt from the interface to the height having the highest temperature when the temperature gradient is measured along an axis parallel to the radial direction of the single crystal. The method according to any one of claims 1 to 4, And measuring the temperature gradient of the silicon melt along the axis parallel to the radial direction of the single crystal in a melt located below the single crystal. The method of claim 6, And the axis penetrates through the center of the silicon single crystal when the temperature of the silicon melt is measured along an axis parallel to the longitudinal direction of the single crystal. The method of claim 6, Wherein the peak is at a point 1/5 to 2/3 from the surface of the melt relative to the total depth of the silicon melt. The method of claim 10, Wherein the peak is at a point from one third to one half of the surface of the melt relative to the total depth of the silicon melt. The method according to any one of claims 1 to 6, A heater is installed on the side of the silicon melt, And growing the silicon single crystal in the heater in a state in which the calorific value of a portion corresponding to 1/5 to 2/3 points from the surface of the melt is increased with respect to the entire depth of the silicon melt in the heater. The method according to any one of claims 1 to 6, And growing the silicon single crystal in a state where a magnetic field is applied to the silicon melt. The method of claim 13, And a magnetic field in a vertical or horizontal direction with respect to the longitudinal direction of the single crystal, or a magnetic field in the form of a cusp. The method of claim 13, A heater is installed on the side of the silicon melt, And growing the silicon single crystal in the heater in a state in which the calorific value of a portion corresponding to 1/5 to 2/3 points from the surface of the melt is increased with respect to the entire depth of the silicon melt in the heater. The method of claim 15, When the temperature of the silicon melt is measured along an axis parallel to the longitudinal direction of the single crystal, the temperature of the melt gradually increases to reach the highest point as the distance from the interface between the melt and the single crystal increases, and gradually decreases. When the predetermined region centered on the highest point is the high temperature region of the melt, the magnetic field promotes the flow of heat from the center of the interface to the high temperature region at the closest portion with the heater. The silicon single crystal growth method of growing the silicon single crystal under the conditions satisfying the following formula when the rotational speed of the crucible containing the silicon melt is Vc and the rotational speed of the silicon single crystal is Vs. 3 ≤ Ln [Vs / Vc] ≤ 5 The method of claim 17, Wherein Vc satisfies Vc ≦ 2 rpm. The method of claim 17, Wherein Vc satisfies Vc ≦ 1 rpm. The method of claim 17, Wherein Vc satisfies Vc ≦ 0.6 rpm. In the apparatus for growing a silicon single crystal by the Czochralski method, chamber; A crucible installed inside the chamber and containing a silicon melt; A heater installed on the side of the crucible to heat the silicon melt, and a heat generation amount of a portion corresponding to 1/5 to 2/3 points from the surface of the melt with respect to the total depth of the silicon melt increased relative to the surroundings; An pulling mechanism for pulling up a silicon single crystal grown from the silicon melt; And A magnet installed on the side of the crucible to apply a magnetic field to the silicon melt Silicon single crystal growth apparatus comprising a. The method of claim 21, And the magnet applies a magnetic field that promotes melt convection toward the center of the single crystal from the closest portion to the heater. The method of claim 21, And the heater further increases the amount of heat generated in a portion corresponding to 1/3 to 1/2 point from the surface of the melt with respect to the total depth of the silicon melt. The method of claim 21, And a heat shield disposed between the silicon single crystal ingot and the crucible so as to surround the silicon single crystal ingot, and shielding heat radiated from the ingot. The method of claim 24, And a cylindrical heat shield attached to the closest portion of the heat shield with the silicon single crystal ingot and surrounding the silicon single crystal ingot.

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