JP5010797B2 - Vertical boat for heat treatment and manufacturing method thereof - Google Patents

Description

  The present invention relates to a vertical boat for heat treatment such as a semiconductor wafer, and more particularly to a vertical boat for heat treatment suitable for heat-treating a silicon wafer and a method for manufacturing the same.

  When a device is manufactured using a wafer cut from a semiconductor ingot such as a silicon single crystal, a number of steps are involved from a wafer processing process to an element formation process. One of these processes is a heat treatment process. This heat treatment step is a very important process performed for the purpose of forming a defect-free layer on the surface layer of the wafer, gettering, crystallization, oxide film formation, impurity diffusion, and the like.

As a diffusion furnace (oxidation / diffusion apparatus) used for such a wafer heat treatment step, for example, for oxidation or impurity diffusion, a large number of wafers W as shown in FIG. A vertical heat treatment furnace 20 that performs heat treatment in a state where it is horizontally supported with an opening is mainly used. The wafer W in the heat treatment furnace 20 can be heated by a heater 24 provided around the reaction chamber 22. During the heat treatment, gas is introduced into the reaction chamber 22 through the gas introduction pipe 26, flows from the upper side to the lower side, and is discharged from the gas exhaust pipe 28 to the outside. The gas to be used varies depending on the purpose of the heat treatment, but H ₂ , N ₂ , O ₂ , Ar, etc. are mainly used. In the case of impurity diffusion, these gases are also used as a carrier gas for the impurity compound gas.

When the wafer W is heat-treated using such a vertical heat treatment furnace 20, a heat treatment vertical boat 11 (hereinafter referred to as “heat treatment boat”, “vertical boat”) for setting a number of wafers W horizontally. Or simply “boat”).
FIG. 10A schematically shows a general heat treatment boat 11. A pair of plate materials (top plate 16a and bottom plate 16b) are connected to both ends of four rod-like (columnar) columns (rods) 14. A large number of slits (grooves) 15 are formed in each support column 14, and a convex portion between the slits 15 acts as a support portion 12 for the wafer W. In addition, the boat for heat processing which formed many groove | channels 15 in the column-shaped support | pillar 14 in this way is generally called the short finger type.
When the wafer W is heat-treated using the vertical boat 11 for heat treatment of this type, as shown in FIG. 10 (b), the support portion 12 formed at the same height of each column 14 is used. The outer periphery of the wafer W is supported at four locations, and the wafer W is supported horizontally.

  When the peripheral edge portion of the wafer W is supported as described above, the weight of the wafer W is concentrated on the support portion, so that the stress generated thereby acts constantly. When this stress exceeds the critical shear stress, dislocations are generated in the wafer. This dislocation spreads to a macroscopic size due to the action of stress and becomes a slip. The occurrence of slip greatly reduces the quality of the wafer, so it is important to prevent this.

However, generally, a slip is remarkably generated on the wafer under a high temperature atmosphere. In particular, as semiconductor devices are highly integrated, the diameter of wafers is increasing in order to increase the device yield per wafer. As a result, the weight of the wafer increases, and accordingly, the stress acting on the wafer tends to increase, and slip is more likely to occur in the wafer.
In addition, due to the increase in wafer size, the temperature difference between the wafer center and the periphery tends to increase especially during temperature rise, and the thermal stress caused by this temperature difference is also a cause of the occurrence of the slip. It has become one.

  As a means for preventing the occurrence of slip during such heat treatment, it has been proposed to use an annular or arcuate auxiliary jig (see Patent Document 1). Specifically, the lower surface peripheral edge of the wafer is supported by the entire circumference or a part of a width of several mm to several tens of mm through an annular or arcuate auxiliary jig placed on the support portion of each support column. A method for supporting the wafer on the entire back surface has also been proposed. If these methods are used, the surface (support surface) for supporting the wafer becomes large and the load and the like are dispersed, so that an effect of suppressing the occurrence of slip can be obtained.

  However, recently, with the high integration of semiconductor devices, not only slip but also scratches generated on the back surface of the wafer are regarded as important. This is because in the case of using a pin chuck type stepper, there is a concern that defocusing may occur when a wafer rear surface scratch is placed on the pin chuck pin. For this reason, attention is paid to a boat for heat treatment and an auxiliary jig of the type that supports the wafer at the periphery rather than the type that supports the wafer on the entire back surface.

  When heat treatment is performed with the wafer supported at the peripheral edge, it is ideal that the wafer be supported along the entire circumference of the lower surface. However, in a general heat treatment furnace, the wafer picks up the back surface of the wafer W as shown in FIG. 11B or the jig 31 that picks up the back surface of the wafer W as shown in FIG. Therefore, when the wafer is transferred to the auxiliary jig, a notch is partially cut out as shown in FIG. 12A so as not to interfere with the auxiliary jig. An arcuate auxiliary jig 37 provided or an annular auxiliary jig 38 provided with a step 39 as shown in FIG. 12B is used.

Since the arc-shaped auxiliary jig 37 as described above is relatively thin and does not need to widen the groove pitch of the boat so much, there is an advantage that the number of batch heat treatments can be increased. However, it is difficult to maintain surface accuracy, and slipping may occur if the heights of both ends of the notch are different.
Further, in the case of the auxiliary jig 38 having a step, it can be manufactured with relatively high surface accuracy and is advantageous for reducing the slip. However, since the jig 38 becomes thicker due to the step 39, the groove pitch of the boat is also increased. It is necessary to widen, and the number of batch heat treatments is reduced.

  Furthermore, these auxiliary jigs 37 and 38 are time-consuming because they are made by punching a circular plate-like member, and are very expensive. Dozens of auxiliary jigs and a vertical boat are used for batch-type heat treatment. If a set is prepared, the cost will be very high compared to a normal vertical boat that directly supports a wafer as shown in FIG.

  On the other hand, there is also proposed a heat treatment boat in which an arc-shaped support portion is integrally formed on one cylinder serving as a boat body (see Patent Document 2). As shown in the cross-sectional view of FIG. 13, this heat treatment boat is provided with an opening (notch) 34 for passing the conveying jig and a notch 35 for venting atmospheric gas, as shown in the cross-sectional view of FIG. A plurality of wide vertical grooves are formed in the vertical direction (axial direction), a wafer is inserted in the horizontal direction, and a horizontal groove for supporting the peripheral edge of the lower surface is formed to the inside of the cylinder. In such a boat, the columns 33a, 33b, 33c, and 33d and the arc-shaped support portions 36a, 36b, 36c, and 36d are integrally formed, so that an arc-shaped auxiliary jig or the like is not used. The lower peripheral edge portion of the wafer W can be intermittently supported by the support portions 36a, 36b, 36c, and 36d.

  However, when the wafer W is supported by a boat provided with a large number of the notches 34 and 35 as described above, when the wafer is bent during heat treatment, the arc-shaped support portions 36a, 36b, 36c, and 36d are at the end portions. There is a problem that slip easily occurs. On the other hand, if the notch 35 for venting the atmospheric gas is not provided in order to prevent the occurrence of such slip, the venting of the atmospheric gas and the movement of heat are hindered, and the wafer W cannot be uniformly heat-treated, There is a problem that the temperature difference in the wafer surface becomes large, and as a result, slip is likely to occur.

JP-A-6-260438 JP-A-5-129214

  In view of such a problem, the present invention provides a vertical boat for heat treatment that can effectively prevent the occurrence of slipping on a wafer or the like during heat treatment and can be uniformly heat-treated. Objective.

In order to achieve the above object, according to the present invention, a top plate, a bottom plate, and a column member fixed between the top plate and the bottom plate, a plurality of grooves are formed in the column member, A vertical boat for heat treatment in which a support portion for horizontally supporting a wafer-like object to be processed is formed between grooves, wherein the support member has an annular or arc-shaped cross section, and the groove Are formed, and an insertion port for inserting the object to be processed, and an annular or continuous arc-shaped support portion integrally formed on the inner side of the column member are provided, and the insertion port A ventilation port is provided at the same height for each support part, and comprises a single column member provided with a column unit formed integrally with the column member between the insertion port and the ventilation port, The wafer-like object to be processed is inserted from the insertion port and is circular or continuous. Vertical boat for heat treatment, characterized in that the Jo of the support portion are intended to be supported along the lower surface peripheral edge portion Ru are provided.

In this way, if one vertical member having an annular or arc-shaped cross section is provided with an annular or continuous arc-shaped support portion integrally and having a vent, a circular arc-shaped boat is used. Auxiliary jigs are not required, and the number of notches in the support portion is one or less, so that the peripheral edge of the lower surface of the wafer can be supported continuously, and even if the groove pitch is narrow, the vent It is possible to sufficiently ensure the passage of atmospheric gas into and out of the boat through.
Therefore, if heat treatment of the semiconductor wafer or the like is performed using this heat treatment boat, the heat treatment can be performed uniformly and the occurrence of slip from the end portion of the support portion can be effectively prevented.

In this case, an annular or continuous arc-shaped support portion having a central angle of 200 ° or more and 360 ° or less may be formed on the support member (claim 2).
If the support member having the central angle of the size as described above is formed on the support member, it is possible to support more than half of the peripheral edge of the lower surface of the wafer, so that the wafer can be supported stably and slip. Can be more effectively suppressed.

The vertical boat for heat treatment can be used for heat treatment of a silicon wafer.
A vertical boat is often used for heat treatment of silicon wafers, and the boat having the configuration according to the present invention is particularly effective in preventing the occurrence of slip. By using this boat, an annealed wafer having almost no slip dislocation and no back surface scratches is obtained. Can be mass-produced at low cost.

It is preferable that the edge part of the support surface of the said support part is chamfered (Claim 4).
By chamfering the edge of the support surface in contact with the object to be processed such as a wafer in this way, it is possible to more reliably prevent the occurrence of slip and scratches.

Further, the support surface of the support portion may be inclined downward toward the inside (claim 5).
If the support surface is inclined as described above, the vicinity of the outer peripheral edge of the wafer or the like is supported, and the occurrence of scratches or the like on the back surface can be more effectively prevented.

Furthermore, according to the present invention, there is provided a method for manufacturing the vertical boat for heat treatment, the step of disposing and fixing a column member having an annular or continuous arc-shaped cross section between the top plate and the bottom plate; The column member is cut from the direction in which the object to be processed is inserted to form a groove, thereby forming an insertion port for inserting the object to be processed, and the object to be processed inside the column member. A step of forming an annular or continuous arc-shaped support portion for supporting the body along the peripheral edge of the lower surface, and the post member is cut and penetrated from another direction at the same height as the insertion port. Thus, there is provided a method of manufacturing a vertical boat for heat treatment, which includes the step of forming the vent and forming a column portion between the insertion port and the vent (Claim 6). .
According to such a method, the vertical boat for heat treatment according to the present invention can be efficiently manufactured, and the manufacturing cost can be kept low.

  Further, as another method, a step of producing a column member having an annular or continuous arc-shaped cross section and a beam formed on the outside, and the column member is disposed between the top plate and the bottom plate And fixing the workpiece to the support member using a circumferential blade having a radius larger than the inner periphery radius of the support member and smaller than the outer periphery radius of the beam portion. An annular for forming the insertion port for inserting the object to be processed by cutting from the direction to be formed and for supporting the object to be processed along the peripheral edge of the lower surface inside the column member Or forming a continuous arc-shaped support portion, and further forming the vent by penetrating a portion other than the beam, and forming the beam portion as the support column. Manufacturing method of vertical boat for heat treatment There is provided (claim 7).

  According to such a method, it is possible to form the wafer insertion port, the support portion, the vent hole, and the support portion at a time by the circumferential blade, and the manufacturing cost can be further reduced.

The vertical boat for heat treatment of the present invention has few end portions of the support portion that induces slip, and sufficiently passes the atmospheric gas into and out of the boat through the vent. Therefore, if the semiconductor wafer is heat-treated using this heat treatment boat, the occurrence of slip can be suppressed extremely effectively and the wafer can be uniformly heat-treated.
In addition, since the occurrence of slip can be suppressed and uniform heat treatment can be performed, the groove pitch can be increased to the same level as a general short finger type vertical boat for heat treatment, and the number of batch processing can be increased. Since the heat treatment time can be shortened by increasing the temperature raising / lowering rate, the productivity can be remarkably improved.

Hereinafter, as a preferred embodiment, a vertical boat for heat treatment according to the present invention used for heat treatment of a silicon wafer will be specifically described with reference to the accompanying drawings.
FIG. 1 shows an outline of an example of a vertical boat for heat treatment according to the present invention. This heat treatment boat 10 has an arc shape with a central angle of about 300 ° between a hollow disk-shaped top plate 1 and a disk-shaped bottom plate 2 arranged in parallel to face the top plate 1. A column member 3 having a transverse cross section (in the present invention, it may be referred to as an arc-shaped column member or simply a column member) is fixed.

In the column member 3, a plurality of grooves 8 are formed at equal intervals perpendicular to the column member 3 so as to have a width wider than the diameter of the wafer to be heat-treated. By forming these grooves 8, an insertion port 4 for inserting a wafer and a continuous arcuate support portion 6 integrally formed inside the support column member 3 are provided. In FIG. 1, the description of the support portion 6 in the middle portion of the boat 10 is omitted.
And since the notch part (opening part) 9 is between the both ends of the circular arc-shaped support part 6, when transferring a wafer from the insertion port 4 with a conveyance jig, a conveyance jig and the support part 6 are used. It can pass without interference.

On the other hand, apart from the insertion port 4, a ventilation port 5 having the same height as the insertion port 4 and the same height as the insertion port 4 is provided for each stage.
Further, between the insertion port 4 and the vent hole 5, column portions 3 a, 3 b, 3 c and 3 d formed integrally with the column member 3 are provided. These column portions 3a, 3b, 3c, 3d are integrally formed in the vertical direction of the column member 3, and function as columns that support the entire boat.

  In the boat 10 configured as described above, the arc-shaped support portions 6 of each stage are continuous, and the cutout portion 9 is only one place. Therefore, the wafer placed on the support portion 6 is supported by the support portion. It will be continuously supported by parts other than the 6 notch part, and generation | occurrence | production of a slip can be suppressed effectively.

However, even if the bottom edge of the wafer is supported by the continuous arc-shaped support portion 6 of the boat 10 according to the present invention, the support is provided when severe heat treatment is performed so that the rate of temperature rise or the rate of temperature fall is very high. When the point contact occurs at the minute convex portion remaining on the surface 6a, or when the wafer is bent during the heat treatment, the point contact occurs particularly at the end portion of the support portion 6 or at the corner portion of the inner periphery, and slip occurs. It can also occur.
Therefore, in order to reliably prevent the occurrence of slip even under severe heat treatment conditions, it is preferable that the support surface 6a is polished and smoothed, or the edge of the support surface 6a is chamfered.

  Moreover, you may form so that the support surface 6a of the support part 6 may incline below toward inner side. Even when the boat 10 according to the present invention supports the wafer along the peripheral edge of the lower surface, some scratches on the back surface are generated in a region several mm wide from the outer periphery in contact with the support portion 6, but the support surface 6 a is not a horizontal surface but a dish. It is possible to further reduce the scratches on the back surface by forming a taper inclined downward on the inside of the boat 10 like the edge of the boat and supporting the wafer only at the edge portion or in the vicinity of the edge portion. it can.

  In such a heat treatment boat 10 according to the present invention, since the continuous arc-shaped support portion 6 is integrally formed inside the support member 3, it is not necessary to separately use an arc-shaped auxiliary jig or the like. The wafer can be widely supported along the peripheral edge of the lower surface, and the support portion 6 has only one notch portion 9, so that slip due to the notch portion hardly occurs. Further, since the vents 5 are provided for each stage of the support portion 6, gas and heat can freely flow inside and outside the boat to uniformly heat the wafer, and the temperature distribution in the wafer surface is uniform. Easy to be. Therefore, in the boat 10 having the configuration according to the present invention, the occurrence of slip can be effectively suppressed and the heat treatment can be uniformly performed on the wafer.

  The size of the arc-shaped support member 3 (the size of the central angle) may be set in consideration of the width of the space for passing the conveying jig, the stable support of the wafer, and the like. It may have a wider central angle. Further, the column member has a circular cross section, that is, a cylindrical support member. For example, an annular support member provided with a step for preventing interference with the transport jig, such as the annular auxiliary jig 38 shown in FIG. A support part may be formed.

  However, the larger the arc-shaped support portion 6 is, the more the load of the wafer can be dispersed and the occurrence of slip can be suppressed. In addition, in consideration of the stability when the wafer is supported, the passage of the conveying jig, etc., It is preferable that the support member 3 is formed with an annular or continuous arc-shaped support portion having a central angle of 200 ° to 360 °. In particular, if the cutout portion 9 or the stepped portion is provided as the support portion 6 (support surface 6a) having a central angle of 340 ° or less, interference between the support portion 6 and the conveying jig can be reliably prevented.

Although the manufacturing method of such a heat treatment boat 10 is not particularly limited, for example, it can be manufactured relatively easily by the following method.
2-5 has shown an example of the manufacturing method of the boat 10 for heat processing.
First, in addition to the top plate 1 and the bottom plate 2, the column member 3 has a continuous arc-shaped cross section as shown in FIG. 2, and the outer peripheral radius is substantially the same as the radius of the top plate 1 and the bottom plate 2. Thus, the column member 3 is produced which is larger than the radius of the wafer to be heat-treated, and whose inner peripheral radius is smaller than the radius of the wafer. The center angle θ of the arc may be determined in consideration of the shape of the wafer conveyance jig. For example, if the column member 3 has an arc-shaped cross section with the center angle θ being about 300 °, the peripheral edge of the lower surface of the wafer The portion can be supported in a wide area, and the notch 9 for passing the conveying jig can be sufficiently secured.

  The manufacturing method of the top plate 1, the bottom plate 2 and the arc-shaped support member 3 itself is not particularly limited. However, in the case of the silicon wafer heat treatment boat 10, as a material, for example, quartz glass, single crystal silicon, polycrystalline Use of silicon or the like can prevent contamination of the wafer, and in particular, a material based on a ceramic material such as silicon carbide (SiC) is preferable because it is extremely excellent in heat resistance in addition to preventing contamination.

  Next, the prepared arcuate column member 3 is disposed between the top plate 1 and the bottom plate 2 and fixed to the top plate 1 and the bottom plate 2. The fixing means is not particularly limited, and any method such as bonding with a binder, fitting, screwing, etc. may be used.

After fixing the arc-shaped column member 3 between the top plate 1 and the bottom plate 2, the groove 8 is formed by cutting the column member 3 from the direction in which the wafer is to be inserted (the position of the notch 9). Thus, the insertion port 4 for inserting the wafer is formed, and a continuous arc-shaped support portion 6 for supporting the wafer along the peripheral edge of the lower surface is formed inside the column member 3.
For such grooving, a grooving machine equipped with a disk-shaped circumferential blade (diamond cutter) 30 that is smaller than the outer peripheral radius of the column member 3 and larger than the radius of the wafer to be heat-treated can be suitably used. . When the groove 8 is formed, the groove 8 is cut from the notch portion of the support member toward the center axis G of the boat 10 until the center axis of the boat 10 and the circumferential blade 30 coincide. As a result, as shown in the cross-sectional view of FIG. 3 and the perspective view of FIG. 4, the groove 8 is formed in the support member 3, and the groove having a width wider than the diameter of the wafer on the side where the circumferential blade 30 is inserted. 8 is formed, and a continuous arc-shaped support portion 6 having an inner diameter smaller than a wafer diameter and a larger outer diameter is formed inside the column member 3.

  After the groove 8 (insertion port 4 and arcuate support portion 6) is formed at a predetermined height in the column member 3 as described above, it is cut through from another direction at the same height as the insertion port 4. By doing so, the vent hole 5 is formed and the column portions 3a, 3b, 3c, 3d between the insertion port 4 and the vent hole 5 are formed. For example, as shown in FIG. 5, the groove is cut by cutting from the outer peripheral side of the column member 3 with a circumferential blade having a smaller radius from three sides opposite to the insertion port 4 (notch portion 9). The three vent holes 5 are formed, and the portions (post portions) 3a, 3b, 3c, and 3d that become the pillars are left. If the vent holes 5 are formed at the same height as the insertion port 4 in this way, a new notch is not formed in the support portion 6, and the circulation of atmospheric gas and the movement of heat are promoted during the heat treatment. Therefore, uniform heat treatment can be performed on the wafer.

  The shape and number of the vents are not limited to those shown in FIG. 1, but may be circular or rectangular. However, at the same height as the groove 8 formed from the direction in which the wafer is inserted as described above, A wide vent hole 5 can be easily formed by grooving and penetrating from the direction. For example, as shown in FIG. 7A, the two vent holes 5 may be formed by cutting from two directions for each step, and the three support portions 3e, 3f, 3g may be formed.

  In addition, as a method of forming the groove | channel 8 (insertion port 4, arc-shaped support part 6) and the vent hole 5 as mentioned above, it is not restricted to the grooving machine using the circumferential blade 30 of a diamond cutter, but the same A technique such as a laser processing machine, a high-pressure jet flow, or a lathe may be used as long as it can be similarly processed with accuracy.

  Further, in order to effectively suppress the occurrence of slip from the end portion of the support portion 6, a point contact on the support surface side of the support portion 6 is prevented as shown in FIG. 6 so that point contact does not occur when the wafer is bent during heat treatment. It is effective to chamfer and round the end 6b and the inner corner 6c. By performing such chamfering, the occurrence of slip can be prevented more effectively.

Further, FIGS. 8A and 8B are views showing another manufacturing method of the boat for heat treatment according to the present invention.
First, as shown in the cross-sectional view of FIG. 8A, a column member 43 having a continuous arc-shaped cross section and having a beam 49 formed on the outer side (outer peripheral surface) is prepared. In the longitudinal direction of the column member 43, in the arc of the cross section, two positions that form a semicircle on the opposite side of the notch 9 and two positions that divide the semicircle into approximately three equal parts, that is, a semicircle Beams 49 are formed at four positions of 0 °, 60 °, 120 °, and 180 °. It should be noted that the outer peripheral radius of the protruding portion that becomes the beam 49 is substantially the same as the radius of the top plate 1 and the bottom plate 2, and the outer peripheral radius of the portion other than the beam is smaller than the radius of the top plate 1 and the like, and the radius of the wafer Larger than.

The column member 43 having such a shape is disposed and fixed between the top plate 1 and the bottom plate 2. Next, a circumferential blade whose radius is larger than the inner peripheral radius of the support member 43 and smaller than the outer periphery radius of the portion that becomes the beam 49, in particular, the size of the support member 43 is smaller than that of the support member 43. The wafer should be inserted as shown in FIG. 8 (b) using a circumferential blade set equal to or slightly larger than the outer radius excluding the beam 49 (size that allows cutting to the boundary with the beam 49). By forming a groove by cutting from the direction (the direction of the notch 9), an insertion port 44 for inserting the wafer is formed and the wafer is supported inside the support member 43 along the peripheral edge of the lower surface. A continuous arc-shaped support portion 46 is formed.
Further, the vent 45 is formed by cutting with a circumferential blade as it is and penetrating the part other than the beam, and the beam part is formed as the column parts 43a, 43b, 43c, 43d.

  By performing such grooving once, in addition to the wafer insertion port 44 and the continuous arc-shaped support portion 46, the support portions 43a, 43b, 43c and 43d and the vent hole 45 are simultaneously formed from the same material. And no new cutouts are formed. That is, the inner part remaining after forming a groove in the column member 43 becomes an arc-shaped wafer support portion 46 having a particularly wide support area, and the uncut portion of the beam serves as a column supporting the entire boat. A vent 45 is formed between the portions 43a, 43b, 43c, and 43d. Accordingly, less grooving is required and the manufacturing cost can be further reduced.

Examples of the present invention and comparative examples will be described below.
Example 1
Manufacture of vertical boat for heat treatment Silicon carbide (SiC) member having a cross-sectional shape of a continuous arc having an outer radius of 165 mm, an inner radius of 147 mm, a central angle of 300 °, and a length of 930 mm Was made. And the corner | angular part (equivalent to 6c of FIG. 6) of the inner peripheral side of the end surface of a longitudinal direction was chamfered in R25.

  As a member serving as a top plate, a hollow disk having an outer diameter (diameter) of 330 mm, an inner diameter (diameter) of 270 mm, and a thickness of 4 mm, and as a member serving as a bottom plate, a disk having a diameter of 330 mm and a thickness of 5 mm, Each was made of SiC.

Between the top plate and the bottom plate, the arc-shaped support member was fixed by bonding with a carbon-based binder. At this time, as shown in FIG. 2, the outer periphery of the support member and the outer periphery of the top plate / bottom plate were aligned with each other. In addition, the angle A formed by the both ends of the arc of the column member and the center axis G of the boat is 60 °, and a notch portion through which the conveying jig passes is sufficiently secured.
Subsequently, in order to impregnate Si with SiC grain boundaries constituting the integrated members, they were immersed in molten Si.

For forming the groove, a grooving machine equipped with a diamond cutter circumferential blade having a diameter of 303 mm was used.
First, in the grooving machine, the integrated strut member is connected to the angle A / the angle formed by the approach direction of the circumferential blade, the center axis G of the boat, and one end a of the strut member as shown in FIG. 2 was set to 30 °. And the width of the groove in the vertical direction is set to 6.6 mm, the thickness of the support portion formed between the grooves is set to 3.0 mm, the number of grooves is set to 95, and the center of the circumferential blade is the center axis G of the boat. By inserting the circumferential blade until it coincided, a groove was formed in the support member and an arc-shaped support portion continuous inside was formed. By such an operation, each groove (wafer insertion port, arcuate support portion) was sequentially formed as shown in FIG.

  Subsequently, as shown in FIG. 5, the integrated member is fixed to the grooving machine so that the angle B formed by the circumferential blade approach direction, the boat center axis G, and one end a of the support member is 85 °. did. In this case, a circumferential blade having a diameter of 200 mm was used, and the support member was cut and penetrated from the same height as the groove formed earlier from the direction in which the wafer should be inserted. Furthermore, it penetrated from the side facing the insertion port in the same manner, and three vent holes each having a width of 70 mm were formed on each column member.

  After forming each groove (insertion slot, support section, support section, and vent hole) as described above, chamfering is applied to the edge of the support surface of each support section, and in particular, the support surface and end face of the support section intersect. The corner (6b in FIG. 6) to be chamfered with R15.

  After the acid cleaning was performed on the boat shape by the series of processes as described above, an SiC-CVD coat film of about 100 μm was formed. Since the surface of this SiC-CVD coating film has a Ra of about 1 μm and there is a risk of slipping due to point contact occurring on a minute convex surface, the support surface is smoothed by polishing until Ra reaches about 0.03 μm. went.

Heat treatment of silicon wafer As a wafer to be heat-treated, a mirror-polished silicon wafer having a diameter of 300 mm and a thickness of 779 μm was prepared.
As the heat treatment boat, a heat treatment vertical boat 10 having an arcuate support portion as shown in FIG. 1 manufactured in Example 1 was used.

Ninety-five wafers were placed on this boat so that the peripheral edge of the lower surface of the wafer was evenly in contact with the arc-shaped support surface, and carried into a heat treatment furnace as shown in FIG. Then, heat treatment was performed in an oven at 1200 ° C. for 1 hour in an argon atmosphere.
After the heat treatment, the boat was taken out from the heat treatment furnace, and the occurrence of slip dislocation was confirmed visually and by X-ray Lang method on 75 wafers excluding 10 wafers from the top and 10 wafers from the bottom.
As a result, no slip dislocation was observed by either visual observation or X-ray Lang method.

(Comparative Experiment 1)
Using a general vertical boat for heat treatment (short finger type) as shown in FIG. 10, the silicon wafer was heat-treated in the same manner as the above experiment.
After heat treatment, when the occurrence of slip dislocation was observed visually and by X-ray Lang method, there were many wafers that could clearly recognize the occurrence of slip dislocation by visual observation, and the slip dislocation occurrence rate evaluated by X-ray Lang method was 90% or more, and slip dislocation was confirmed in most wafers.

(Comparative experiment 2)
Further, by forming vertical grooves in the vertical direction (axial direction) for one cylinder as a boat body as shown in FIG. The silicon wafer was heat-treated in the same manner as in the above experiment, using an integrated vertical boat for heat treatment provided with openings (notches) for gas ventilation.
After heat treatment, the occurrence of slip dislocations was observed visually and by X-ray Lang method. Some slip dislocations could be confirmed by visual observation. Also, when evaluated by X-ray Lang method, slip dislocation occurrence rate Was almost 30%. Although the slip dislocation occurrence rate was lower than in the case of Comparative Experiment 1, in addition to the vertical groove 34 for passing through the conveying jig, a plurality of gas support vertical grooves 35 formed along the vertical direction were formed in the wafer support portion 36 at a plurality of locations. It is considered that the occurrence of slip was promoted due to the presence of the disconnected portion.

  The present invention is not limited to the above embodiment. The above embodiment is merely an example, and the present invention has the same configuration as that of the technical idea described in the claims of the present invention, and any device that exhibits the same function and effect is the present invention. It is included in the technical scope of the invention.

  For example, when using a wafer conveyance system with a wafer lift mechanism, an annular support portion 7 is formed on a support member 13 having an annular cross section as shown in FIG. It may be supported by Thus, if it supports by a perimeter, generation | occurrence | production of a slip can be suppressed more effectively.

It is a perspective view which shows an example of the vertical boat for heat processing which concerns on this invention. It is sectional drawing before the groove formation process of the boat for heat processing of FIG. It is sectional drawing after the groove formation process of the boat for heat processing of FIG. It is a perspective view explaining the groove formation process of the boat for heat processing. FIG. 2 is a cross-sectional view of the heat treatment boat of FIG. It is the perspective view which expanded the edge part of the support part enclosed by C of FIG. It is sectional drawing which shows the other example of the vertical boat for heat processing which concerns on this invention. (A) Arc-shaped column member (b) Ring-shaped column member It is sectional drawing which shows the further another example of the vertical boat for heat processing which concerns on this invention. (A) Before groove formation processing (b) After groove formation processing It is the schematic which shows an example of a vertical heat processing furnace. It is the schematic which shows an example of the conventional vertical boat for heat processing. (A) Front view (b) Cross-sectional view in the lateral direction (state in which the wafer is supported) It is the schematic which shows the example of a conveyance jig. (A) Scooping method (b) Adsorption method It is a perspective view which shows the example of the auxiliary | assistant jig | tool for wafer periphery part support. (A) Arc-shaped auxiliary jig (b) An annular auxiliary jig with a step It is a schematic sectional drawing of the conventional vertical boat for integrated heat processing.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Top plate, 2 ... Bottom plate, 3 ... Column member, 3a-3g ... Column part,
4 ... wafer insertion port, 5 ... ventilation port, 6 ... continuous arcuate support,
7 ... Annular support, 6a ... Wafer support surface, 8 ... Groove, 9 ... Notch (opening),
10 ... Vertical boat for heat treatment, 20 ... Heat treatment furnace, 30 ... Circumferential blade, θ ... Center angle,
W ... wah.

Claims (7)

It has a top plate, a bottom plate, and a column member fixed between the top plate and the bottom plate. A plurality of grooves are formed in the column member, and a wafer-like object to be processed is horizontally supported between the grooves. A vertical boat for heat treatment in which a support portion is formed, wherein the support member has an annular or arc-shaped cross section, and the groove is formed to insert the object to be processed. And an annular or continuous arc-shaped support portion integrally formed on the inner side of the support member, and a vent hole is provided for each support portion at the same height as the insertion port. together is, consists of one strut member is provided with integrally formed struts in the strut member between the insertion opening and vent, the wafer-like object to be processed is, from the insertion port Inserted and supported along the peripheral edge of the lower surface by the annular or continuous arc-shaped support part Vertical boat for heat treatment, characterized in that it is intended to.   2. The vertical boat for heat treatment according to claim 1, wherein the support member is formed with an annular or continuous arc-shaped support portion having a central angle of 200 ° to 360 °.   The vertical boat for heat treatment according to claim 1 or 2, wherein the vertical boat for heat treatment is for heat treatment of a silicon wafer.   The vertical boat for heat treatment according to any one of claims 1 to 3, wherein an edge portion of the support surface of the support portion is chamfered.   The vertical boat for heat treatment according to any one of claims 1 to 4, wherein a support surface of the support portion is inclined downward toward the inside.   The method for manufacturing a vertical boat for heat treatment according to any one of claims 1 to 5, wherein a column member having an annular or continuous arc-shaped cross section is provided between the top plate and the bottom plate. Forming the insertion port for inserting the object to be processed by forming a groove by cutting the object to be inserted from the direction in which the object is to be inserted. A step of forming an annular or continuous arc-shaped support part for supporting the object to be processed along the peripheral edge of the lower surface inside the support member, and the support member are separated at the same height as the insertion port. A method of manufacturing a vertical boat for heat treatment, comprising the step of forming the vent hole by cutting and penetrating from the direction of, and forming a column portion between the insertion port and the vent hole.   A method for manufacturing a vertical boat for heat treatment according to any one of claims 1 to 5, wherein the boat has a circular or continuous arc-shaped cross section, and a beam is formed outside. A strut member having a radius larger than an inner peripheral radius of the strut member, and a step of arranging the strut member between the top plate and the bottom plate and fixing the strut member. While using a circumferential blade smaller than the outer peripheral radius of the portion to be a beam, forming an insertion port for inserting the object to be processed by forming a groove by cutting the object to be processed in a direction to be inserted An annular or continuous arc-shaped support part for supporting the object to be processed along the peripheral edge of the lower surface is formed inside the support member, and the vent is formed by penetrating a part other than the beam. And the beam portion is connected to the column portion. For heat treatment vertical boat method of manufacturing, which comprises the step of to form.

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