JP2010153468A - Thermal treatment apparatus of semiconductor wafer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To successively start the thermal treatment of semiconductor wafers one by one. <P>SOLUTION: The thermal treatment apparatus of the semiconductor wafer includes a tubular heating furnace, a plurality of carrying shafts extended inside the heating furnace and an actuator for rotating the plurality of carrying shafts respectively. The tubular heating furnace is extended from a carry-in port where the semiconductor wafer can be carried in to a carry-away port where the semiconductor wafer can be carried away. The plurality of carrying shafts are extended from the carry-in port through the inside of the heating furnace to the carry-away port and are disposed in such a positional relation that they can be abutted to the outer peripheral edge of the semiconductor wafer. On each carrying shaft, a spiral groove which is spirally extended along an axial direction and is capable of receiving the outer peripheral edge of the semiconductor wafer is formed. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a technique for heat-treating a semiconductor wafer.

  Patent Document 1 discloses a technique for heat-treating a semiconductor wafer. In this technique, a large number of semiconductor wafers are collectively heat-treated by placing a large number of semiconductor wafers on a jig and storing the jig in a heating furnace.

Japanese Patent Laid-Open No. 2003-1000064

When heat-treating a semiconductor wafer, the required processing time is long, and as in the technique disclosed in Patent Document 1, a plurality of semiconductor wafers are often heat-treated in a lump. However, in the method of collectively heat-treating a plurality of semiconductor wafers, the work-in-process semiconductor wafer is unnecessarily retained until a predetermined number of semiconductor wafers are supplied from the previous process. Further, even after the heat treatment, a large number of heat-treated semiconductor wafers are collectively supplied to the subsequent process, and the work-in-process semiconductor wafers are unnecessarily retained. There is a need for a technique capable of sequentially starting the heat treatment of the semiconductor wafer supplied from the previous process.
The present invention solves the above problems. The present invention provides a technique capable of sequentially starting the heat treatment of a semiconductor wafer.

  The present invention is embodied in a heat treatment apparatus for heat treating a semiconductor wafer. This heat treatment apparatus includes a tubular heating furnace, a plurality of conveying shafts extending in the heating furnace, and an actuator for rotating the plurality of conveying shafts. The tubular heating furnace extends from a carry-in port that can carry in a semiconductor wafer to a carry-out port that can carry out the semiconductor wafer. The plurality of transfer shafts extend from the carry-in port through the heating furnace to the carry-out port, and are arranged in a positional relationship capable of contacting the outer peripheral edge of the semiconductor wafer. Each conveyance shaft is formed with a spiral groove that extends in a spiral shape along the axial direction and can receive the outer peripheral edge of the semiconductor wafer.

  In this heat treatment apparatus, a spiral groove is formed on a transfer shaft extending in a heating furnace, and a semiconductor wafer to be processed is supported by the spiral grooves formed on a plurality of transfer shafts. The semiconductor wafer supported by the spiral groove is carried out from the carry-in entrance through the heating furnace to the carry-out exit as the carrying shaft rotates. Semiconductor wafers can be sequentially placed on the rotating transfer shaft, and the semiconductor wafers placed on the transfer shaft are sequentially heat-treated in a heating furnace. Since the heat treatment of semiconductor wafers supplied from the previous process can be started one by one in sequence, in-process semiconductor wafers can be processed in the process compared to the conventional technology that heat-treats many semiconductor wafers at once. It does not stay unnecessarily.

In the above-described conveyance shaft, it is preferable that the lead of the spiral groove changes along the axial direction of the conveyance shaft. In this case, it is also preferable that the lead of the spiral groove changes stepwise along the axial direction of the transport shaft, or it also changes continuously along the axial direction of the transport shaft.
Here, the lead of the spiral groove is the amount of movement that the spiral groove moves in the axial direction of the transport shaft when the spiral groove makes one turn around the transport shaft. It becomes equal to the pitch (interval) of the groove. That is, the lead of the spiral groove corresponds to the distance that the semiconductor wafer is transported when the transport shaft makes one rotation. For example, the shorter the lead of the spiral groove, the faster the transport speed of the semiconductor wafer with respect to the rotational speed of the transport shaft. Will be late. Therefore, if the lead of the spiral groove is appropriately changed along the axial direction of the transfer shaft, the transfer speed of the semiconductor wafer can be changed appropriately for each position in the heating furnace even if the rotation speed of the transfer shaft is kept constant. Can do.

When the lead of the spiral groove is changed as described above, it is preferable to shorten the lead of the spiral groove in a range located in the middle section of the heating furnace.
According to this configuration, the semiconductor wafer can stay for a long time in the middle section of the heating furnace maintained at a relatively high temperature, and sufficient heat treatment can be performed on the semiconductor wafer. In other words, the heat treatment that requires a relatively long processing time can be performed by a relatively short heating furnace.

The plurality of transport shafts are each formed with spiral grooves that rotate in the same direction, and the actuator preferably rotates the plurality of transport shafts in the same direction.
According to this configuration, the semiconductor wafer supported on the transport shaft is transported while rotating due to the frictional force generated between the semiconductor wafer and the transport shaft. By transporting the semiconductor wafer while rotating, even if there is a temperature difference in the heating furnace in a cross section perpendicular to the transport direction, a uniform thermal history can be given to the entire surface of the semiconductor wafer. In other words, it is not necessary to make the temperature in the heating furnace uniform in a cross section perpendicular to the conveying direction, and the configuration and control of the heater for heating the inside of the heating furnace can be simplified. .

When the semiconductor wafer is conveyed while rotating with the above-described configuration, it is preferable to form irregularities on at least a part of the inner surface of the spiral groove.
By forming irregularities on the inner surface of the spiral groove, the frictional force generated between the semiconductor wafer and the transfer shaft can be increased, and the semiconductor wafer can be rotated more reliably.

  According to the present invention, the heat treatment of the semiconductor wafers supplied from the previous process can be sequentially started one by one, so that the work-in-process semiconductor wafer can be avoided from being unnecessarily retained in the process. In addition, it becomes possible to uniformly perform heat treatment of a plurality of semiconductor wafers, and the manufacturing quality of a semiconductor device manufactured from the semiconductor wafer can be stabilized.

Preferred features for carrying out the present invention are listed.
(Embodiment 1) The conveyance shaft can be formed of, for example, quartz, silicon carbide, alumina, or the like. However, the material for forming the transfer shaft is not limited to these materials, and other materials having relatively high strength and higher heat resistance than the semiconductor wafer to be heat-treated can be used.
(Mode 2) It is preferable that the plurality of transfer shafts support the semiconductor wafer substantially perpendicularly to the transfer direction.
(Mode 3) The heating furnace is preferably provided with a plurality of heaters surrounding the heating furnace from the circumferential direction along the axial direction of the heating furnace. In this case, a plurality of heaters having a ring shape may be provided along the axial direction of the heating furnace, or a plurality of panel heaters arranged so as to surround the tubular heating furnace from the circumferential direction are arranged in the axial direction of the heating furnace. It is preferable to provide a plurality along the line.
(Mode 4) The heating furnace preferably extends substantially horizontally from the carry-in port to the carry-out port. According to this configuration, the formation of an airflow toward the carry-in port or the carry-out port in the heating furnace is prevented, and entry of foreign matters such as dust into the heating furnace from the carry-in port or the carry-out port can be suppressed.
(Mode 5) It is preferable that the heating furnace is provided with a stable gas supply pipe capable of supplying a stable (non-reactive) gas to the semiconductor wafer. In this case, it is preferable that the stable gas supply pipe can supply a stable gas over the entire section in the heating furnace. Here, examples of the stable gas include nitrogen gas.
(Mode 6) The heating furnace is preferably provided with a reactive gas supply pipe capable of supplying a reactive gas for forming a film on the surface of the semiconductor wafer. In this case, it is preferable that the reactive gas supply pipe can supply the reactive gas only to a range located in the middle section of the heating furnace. Here, examples of the reactive gas include oxygen gas for forming an oxide film, silane gas for forming a polysilicon film, and the like.
(Mode 7) The heating furnace is preferably provided with a gas discharge pipe for discharging the gas in the heating furnace. In this case, it is preferable that the gas discharge pipe is opposed to the stable gas supply pipe and the reaction gas supply pipe with the semiconductor wafer to be conveyed interposed therebetween.

  Embodiments of the present invention will be described with reference to the drawings. In FIG. 1, the schematic diagram which shows the structure of the heat processing apparatus 10 of a present Example is shown. 2 is a cross-sectional view taken along line II-II in FIG. The heat treatment apparatus 10 is an apparatus for performing a heat treatment for heating the semiconductor wafer 100. By the heat treatment by the heat treatment apparatus 10, an annealing treatment for diffusing conductive impurities and a film formation treatment such as an oxide film can be performed. In the present specification, the annealing process and the film forming process accompanied by heating of the semiconductor wafer 100 may be collectively referred to simply as heat treatment.

As shown in FIGS. 1 and 2, the heat treatment apparatus 10 mainly includes a heating furnace 12 that heats the semiconductor wafer 100 and a plurality of transfer shafts 40 that transfer the semiconductor wafer 100 within the heating furnace 12. The plurality of transport shafts 40 are provided with motors 48. The motor 48 rotates each of the plurality of transport shafts 40.
The heating furnace 12 has a tube shape with a substantially circular cross section. Here, the inner diameter of the heating furnace 12 is sufficiently larger than the diameter of the semiconductor wafer 100. At one end of the heating furnace 12, a carry-in port 12 a that opens to a size capable of carrying the semiconductor wafer 100 is formed. At the other end of the heating furnace 12, a carry-out port 12 b that opens to a size that allows the semiconductor wafer 100 to be carried out is formed. That is, the diameters of the carry-in port 12 a and the carry-out port 12 b are sufficiently larger than the diameter of the semiconductor wafer 100.
As will be described in detail later, the semiconductor wafer 100 to be processed is carried into the heating furnace 12 from the carry-in entrance 12a by the plurality of carrying shafts 40, is carried through the heating furnace 12, and is carried out from the carry-out exit 12b. . The plurality of transfer shafts 40 sequentially carry the semiconductor wafers 100 supplied from the previous process into the heating furnace 12, transfer the inside of the heating furnace 12, and sequentially carry out the outside of the heating furnace 12.

The heating furnace 12 is disposed substantially horizontally. That is, the carry-in port 12a and the carry-out port 12b have the same vertical height position and are located in the same horizontal plane. And the heating furnace 12 is extended substantially linearly in the horizontal surface from the carrying-in entrance 12a to the carrying-out exit 12b.
According to this structure, it can suppress that foreign materials, such as dust, penetrate | invade into the heating furnace 12 from the carrying-in entrance 12a or the carrying-out exit 12b. In other words, when the height of the carry-in port 12a and the carry-out port 12b is different and the tubular heating furnace 12 is inclined with respect to the horizontal direction, dust or the like enters the heating furnace 12 from the carry-in port 12a or the carry-out port 12b. It becomes easy for foreign matter to enter. For example, it is assumed that the carry-out port 12b is located above the carry-in port 12a and the heating furnace 12 is inclined upward toward the carry-out port 12b. In this case, the high-temperature gas in the heating furnace 12 flows toward the carry-out port 12b located above. As a result, an air flow from the carry-in port 12a to the carry-out port 12b is generated in the heating furnace 12, and a lot of outside air flows from the carry-in port 12a. At this time, foreign matters such as dust contained in the outside air easily enter the heating furnace 12 together with the outside air. Similarly, when the carry-in port 12a is positioned above the carry-out port 12b and the heating furnace 12 is inclined upward toward the carry-in port 12a, the foreign matter is heated from the carry-out port 12b with the outside air. It becomes easy to enter the furnace 12.

A plurality of heaters 14 are provided in the heating furnace 12. The heater 14 has a ring shape and surrounds the tubular heating furnace 12 from the circumferential direction. The inner peripheral surface of the heater 14 is a heater surface that radiates heat toward the inside of the heating furnace 12. The plurality of heaters 14 are arranged along the axial direction of the heating furnace 12 (left-right direction in FIG. 1). In the present embodiment, five heaters 14 having a ring shape are arranged along the axial direction of the heating furnace 12.
Here, the individual heaters 14 are not limited to ring-shaped ones. For example, a plurality of panel heaters (planar heaters) may be arranged around the heating furnace 12.

The outputs of the plurality of heaters 14 are individually controlled by a temperature control device (not shown). Thereby, as shown in FIG. 3, a temperature distribution is formed in the heating furnace 12 along the direction from the carry-in port 12a to the carry-out port 12b (hereinafter simply referred to as the carrying direction). Here, in the graph shown in FIG. 3, the horizontal axis X indicates the distance from the carry-in port 12a, and the vertical axis T indicates the temperature.
As shown in FIGS. 1 and 3, in the first section S <b> 1 located on the carry-in port 12 a side of the heating furnace 12, the temperature in the heating furnace 12 continuously increases along the transport direction. Since the carry-in port 12a is always open, the temperature near the room temperature is near the carry-in port 12a. Next, in the second section S2 located in the middle portion of the heating furnace 12, the temperature in the heating furnace 12 is maintained substantially constant. The temperature in the second section S2 can be set to a required processing temperature in accordance with the heat treatment performed on the semiconductor wafer 100. Finally, in the third section S3 located on the carry-out port 12b side of the heating furnace 12, the temperature in the heating furnace 12 is lowered along the transport direction. Since the carry-out port 12b is always open, the temperature near the room temperature is near the carry-out port 12b.

The temperature gradient as described above is formed in the heating furnace 12. Thereby, the temperature of the semiconductor wafer 100 carried into the heating furnace 12 from the carry-in port 12 a is gradually raised while being transferred into the heating furnace 12. Further, the semiconductor wafer 100 unloaded from the heating furnace 12 from the unloading port 12b is gradually lowered in temperature while being transferred to the unloading port 12b. Thereby, when the semiconductor wafer 100 is carried into the heating furnace 12 and when the semiconductor wafer 100 is carried out of the heating furnace 12, the temperature of the semiconductor wafer 100 rapidly changes due to a temperature difference with the outside. It is prevented. By preventing a rapid temperature change of the semiconductor wafer 100, the semiconductor wafer 100 is prevented from being damaged due to thermal stress.
All the semiconductor wafers 100 are similarly transported in the heating furnace 12 from the carry-in port 12a to the carry-out port 12b. Therefore, even if the temperature distribution in the heating furnace 12 is not uniform along the conveyance direction, substantially the same thermal history can be given to all the semiconductor wafers 100.

  As shown in FIGS. 1 and 2, the heating furnace 12 is provided with a stable gas supply pipe 20 and a reaction gas supply pipe 24. The stable gas supply pipe 20 is provided in the upper part in the heating furnace 12, and extends from the carry-in port 12a of the heating furnace 12 to the carry-out port 12b. A plurality of discharge ports 20 a for discharging gas are formed in the stable gas supply pipe 20 over all the sections S 1, S 2, S 3 of the heating furnace 12. A nitrogen supply device 22 for supplying nitrogen gas is connected to one end of the stable gas supply pipe 20 so that nitrogen gas can be supplied over the entire sections S1, S2, and S3 of the heating furnace 12. The stable gas supply pipe 20 is a pipe for supplying a stable (non-reactive) gas to the semiconductor wafer 100, and the supplied gas is not limited to nitrogen gas. By filling the inside of the heating furnace 12 with a stable gas, the semiconductor wafer 100 can be heat-treated without unnecessarily degrading the semiconductor wafer 100. It is also effective to increase the amount of nitrogen gas supplied from the stable gas supply pipe 20 in the vicinity of the carry-in port 12a and the carry-out port 12b. In this case, it is possible to effectively prevent the atmosphere from entering from the carry-in port 12a and the carry-out port 12b.

  The reaction gas supply pipe 24 is provided in the upper part in the heating furnace 12, and extends from the carry-in port 12a of the heating furnace 12 to a position exceeding the second section S2. The reaction gas supply pipe 24 is also formed with a plurality of discharge ports 24a for discharging gas. However, in the reaction gas supply pipe 24, the plurality of discharge ports 24a are formed in a range located in the second section S2 instead of all the sections S1, S2, and S3 of the heating furnace 12. An oxygen supply device 26 that supplies oxygen gas is connected to one end of the reaction gas supply pipe 24, and oxygen gas can be supplied to the second section S <b> 2 located in the middle of the heating furnace 12. By supplying oxygen gas to the second section S2 maintained at a high temperature, an oxide film can be formed on the surface of the semiconductor wafer 100 at least in the second section S2. At this time, nitrogen gas is simultaneously supplied through the stable gas supply pipe 20, and air can be prevented from entering the heating furnace 12 from the outside. Accordingly, the oxygen concentration in the second section S2 can be accurately adjusted by adjusting the oxygen supply amount from the reaction gas supply pipe 24.

  Here, the reactive gas supply pipe 24 is not limited to oxygen gas, and can supply other reactive gas. For example, if a supply device such as silane gas is connected to the reaction gas supply pipe 24, silane gas or the like can be supplied to the second section S2 maintained at a high temperature, and a polysilicon film is formed on the surface of the semiconductor wafer 100. Can do. As described above, in the heat treatment apparatus 10, not only annealing the semiconductor wafer 100 but also changing the type of reactive gas supplied by the reaction gas supply pipe 24, an oxide film or polycrystal is formed on the surface of the semiconductor wafer 100. Various types of coatings such as silicon films can be formed.

  As shown in FIGS. 1 and 2, the heating furnace 12 is also provided with a gas discharge pipe 28. The gas discharge pipe 28 is provided in the lower part in the heating furnace 12, and extends from the carry-out port 12b of the heating furnace 12 to a position exceeding the second section S2. The gas discharge pipe 28 is formed with a plurality of suction holes 28a for sucking gas. The plurality of suction ports 28a are formed in a range located in the second section S2 instead of all the sections S1, S2, and S3 of the heating furnace 12. A suction pump (not shown) is connected to one end of the gas discharge pipe 28. Thereby, the gas discharge pipe 28 sucks the gas in the second section S <b> 2 located in the middle of the heating furnace 12 and discharges the sucked gas to the outside of the heating furnace 12.

  The gas discharge pipe 28 is opposed to the stable gas supply pipe 20 and the reaction gas supply pipe 24 located on the upper side with the semiconductor wafer 100 to be transferred interposed therebetween. Thereby, at least in the second section S2, an airflow from the upper side to the lower side is formed. As will be described in detail later, the semiconductor wafer 100 is supported perpendicular to the transport direction. Therefore, the airflow flows substantially parallel to the surface of the semiconductor wafer 100. As described above, in the second section located in the middle of the heating furnace 12, a film such as an oxide film is formed. If an air flow parallel to the surface of the semiconductor wafer 100 is formed in the second section S2, no foreign matter is blown on the surface of the semiconductor wafer 100, and the attached foreign matter may be removed. Therefore, it is possible to prevent impurities from being mixed into the film to be formed. Further, foreign matters floating in the heating furnace 12 are also quickly discharged to the outside of the heating furnace 12.

As shown in FIG. 1, the heating furnace 12 is provided with a first oxygen meter 31 and a second oxygen meter 32. The first oximeter 31 and the second oximeter 32 have sensor heads 31 a and 32 a disposed in the heating furnace 12, and measure the oxygen concentration in the heating furnace 12.
The first oximeter 31 monitors the oxygen concentration in the second section S2, and the sensor head 31a is disposed in the vicinity of the boundary between the first section S1 and the second section S2. The reason why the sensor head 31a is arranged at the boundary position instead of within the second section S2 is to monitor the minimum value of the oxygen concentration in the second section S2. The oxygen concentration measured by the first oxygen meter 31 is used for oxygen gas supply amount control by the oxygen supply device 26. That is, the oxygen supply device 26 increases or decreases the supply amount of the oxygen gas supplied to the reaction gas supply pipe 24 according to the measurement value by the first oxygen meter 31. Thereby, the oxygen concentration in the second section S2 is maintained at a required concentration. In addition, when supplying reactive gas other than oxygen from the reactive gas supply pipe 24, it is preferable to install a sensor for measuring the concentration of the reactive gas in place of the first oxygen meter 31.
The second oximeter 32 monitors outside air entering from the carry-in port 12a, and the sensor head 32a is disposed in the vicinity of the carry-in port 12a. The oxygen concentration measured by the second oximeter 32 is used for nitrogen gas supply amount control by the nitrogen supply device 22. That is, the nitrogen supply device 22 increases or decreases the supply amount of nitrogen gas supplied to the stable gas supply pipe 20 according to the measurement value by the second oximeter 32. This reliably prevents outside air from entering from the carry-in port 12a and the carry-out port 12b.

Next, the conveyance shaft 40 will be described. As shown in FIGS. 1 and 2, in the heat treatment apparatus 10 of the present embodiment, four transport shafts 40 are provided. Each conveyance shaft 40 is made of quartz and has heat resistance capable of withstanding up to about 1200 ° C. In addition, the conveyance shaft 40 can also be formed with the other material which has required heat resistance.
The plurality of transfer shafts 40 extend in parallel to each other from the carry-in port 12a to the carry-out port 12b through the heating furnace 12. Note that both ends of the plurality of transport shafts 40 extend to the outside of the heating furnace 12. As well shown in FIG. 2, the four transfer shafts 40 are arranged on the same circumference so as to contact the outer peripheral edge 100 e of the semiconductor wafer 100. An arrow D1 in FIG. 2 indicates the rotation direction of each conveyance shaft 40. As indicated by an arrow D1, the four transport shafts 40 are configured to rotate in the same direction by a motor 48 (see FIG. 1).

FIG. 4 shows an enlarged part of the transport shaft 40. As shown in FIG. 4, the conveying shaft 40 is formed with a spiral groove 42 (screw groove) extending in a spiral shape along the axial direction thereof. The spiral groove 42 has a width larger than the thickness of the semiconductor wafer 100 and can receive the outer peripheral edge 100 e of the semiconductor wafer 100. In addition, a number of grooves extending in the axial direction are formed on the bottom surface 42a of the spiral groove 42 so that minute irregularities are formed.
In the heat treatment apparatus 10 of the present embodiment, the same spiral groove 42 is formed on all the conveyance shafts 40. The four transfer shafts 40 can support the outer peripheral edge 100 e of the semiconductor wafer 100 by the spiral groove 42. At this time, the semiconductor wafer 100 is supported perpendicular to the transport direction. When the transfer shaft 40 is rotated by the motor 48, the semiconductor wafer 100 supported by the transfer shaft 40 is transferred toward the carry-out port 12b. That is, the four transfer shafts 40 transfer the semiconductor wafer 100 by the principle of screw feeding.

In the present embodiment, each conveyance shaft 40 is formed with a spiral groove 42 that turns in the same direction. As shown in FIG. 2, each conveyance shaft 40 is configured to rotate in the same direction D <b> 1 by a motor 48. According to this configuration, the semiconductor wafer 100 is conveyed while rotating in the direction D2 shown in FIG. 2 by the frictional force generated between the semiconductor wafer 100 and the spiral groove 42. In the heating furnace 12, an unavoidable temperature difference may occur in a cross section perpendicular to the transport direction. Even in such a case, if the semiconductor wafer 100 is conveyed while rotating, the entire semiconductor wafer 100 can be uniformly heated without being affected by the temperature difference, and a uniform thermal history can be provided. It becomes possible. Furthermore, since minute irregularities are formed on the bottom surface 42a of the spiral groove 42, the frictional force generated between the semiconductor wafer 100 and the spiral groove 42 is relatively large, and the semiconductor wafer 100 is rotated more reliably. be able to. Furthermore, since the spiral groove 42 can be prevented from sliding with respect to the semiconductor wafer 100 by rotating the semiconductor wafer 100, wear and chipping of the semiconductor wafer 100 can be avoided.
When the above-described advantages are not particularly required, it is not always necessary to rotate the semiconductor wafer 100 when the semiconductor wafer 100 is transferred. In this case, the rotation direction of the spiral groove 42 can be made different for each conveyance shaft 40, and the rotation direction of the conveyance shaft 40 can be made different accordingly. That is, it is only necessary that the spiral groove 42 is turned in each transfer shaft 40 according to the rotation direction so that the semiconductor wafer 100 can be transferred.

  In the heat treatment apparatus 10, it is also effective to change the lead of the spiral groove 42 formed on the transport shaft 40 along the axial direction of the transport shaft 40. Here, the lead of the spiral groove 42 is a moving amount by which the spiral groove 42 moves in the axial direction of the transport shaft 40 when the spiral groove 42 makes one round around the transport shaft 40. That is, the lead of the spiral groove 42 corresponds to the distance to which the semiconductor wafer 100 is transported when the transport shaft 40 makes one rotation. For example, the shorter the lead of the spiral groove 42 is, the faster the transport speed of the transport shaft 40 is. The transfer speed of the semiconductor wafer 100 can be reduced. Therefore, when the lead of the spiral groove 42 is partially changed, the transfer speed of the semiconductor wafer 100 can be changed in a partial range in the transfer direction while keeping the rotation speed of the transfer shaft 40 constant.

In the heat treatment apparatus 10 of the present embodiment, as shown in FIG. 1, the lead of the spiral groove 42 is shortened in a range located in the second section S <b> 2 of the heating furnace 12. Thereby, the semiconductor wafer 100 can be allowed to stay for a long time in the second section S2 where the heat treatment is actually performed. According to this configuration, heat treatment that requires a relatively long processing time can be performed by the relatively short heating furnace 12.
Further, in the heat treatment apparatus 10 of the present embodiment, the lead of the spiral groove 42 is shortened also in the range located in the sections S0 and S4 outside the heating furnace 12. The section S0 located outside the carry-in entrance 12a is a section where the semiconductor wafer 100 is placed on the transfer shaft 40. If the lead of the spiral groove 42 is shortened in this section S0, the moving speed of the spiral groove 42 in the axial direction becomes slow, and the semiconductor wafer 100 can be easily placed on the transport shaft 40. On the other hand, the section S4 located outside the unloading port 12b is a section in which the semiconductor wafer 100 is picked up from the transfer shaft 40. If the lead of the spiral groove 42 is shortened in this section S4, the moving speed of the semiconductor wafer 100 on the transfer shaft 40 becomes slow, and the semiconductor wafer 100 can be easily taken out from the transfer shaft 40.

  As described above, in the heat treatment apparatus 10 of this embodiment, the semiconductor wafers 100 sequentially supplied from the previous process can be sequentially placed on the rotating transfer shaft 40. The semiconductor wafers 100 placed on the transfer shaft 40 are sequentially carried into the heating furnace 12 by the spiral grooves 42 of the transfer shaft 40. The semiconductor wafer 100 carried into the heating furnace 12 is transferred through the heating furnace 12 by the spiral groove 42 of the rotating transfer shaft 40, and heat treatment is performed during that time. Then, the semiconductor wafer 100 that has been heat-treated in the heating furnace 12 is sequentially carried out of the heating furnace 12 by the spiral groove 42 of the rotating transfer shaft 40. As described above, the heat treatment apparatus 10 can sequentially start the heat treatment of the semiconductor wafers 100 one by one and can sequentially complete the wafers one by one. Since it is not necessary to heat-treat the plurality of semiconductor wafers 100 at once, it is possible to efficiently manufacture the semiconductor device without unnecessarily stagnation of work in progress.

  Further, in the heat treatment apparatus 10 of the present embodiment, all the semiconductor wafers 100 are similarly conveyed in the heating furnace 12 from the carry-in port 12a to the carry-out port 12b. That is, unlike the conventional technique in which a plurality of semiconductor wafers 100 are collectively heat-treated, each semiconductor wafer 100 does not stay at a specific position. Thereby, even if the temperature distribution in the heating furnace 12 is not uniform along the conveying direction without the cross section, substantially the same thermal history can be given to all the semiconductor wafers 100. Further, by transporting the semiconductor wafer 100 while rotating, even if the temperature distribution in the heating furnace 12 is not uniform in the cross section perpendicular to the transport direction, the variation of the thermal history applied to the semiconductor wafer 100 is substantially eliminated. You can also.

Further, in the heat treatment apparatus 10 of the present embodiment, the semiconductor wafer 100 to be transferred is supported perpendicular to the transfer direction. The temperature in the heating furnace 12 decreases toward the carry-in port 12a or the carry-out port 12b. Therefore, a temperature gradient is generated in the heating furnace 12 along the transfer direction of the semiconductor wafer 100. In this case, for example, when the semiconductor wafer 100 is held in parallel with the transport direction, between the portion located in the front of the semiconductor wafer 100 in the transport direction and the portion located in the rear of the semiconductor wafer 100 in the transport direction, A relatively large temperature difference occurs. When such a temperature difference occurs in the semiconductor wafer 100, a large thermal stress is generated in the semiconductor wafer 100, which may damage the semiconductor wafer 100. On the other hand, if the semiconductor wafer 100 is supported substantially perpendicularly to the transport direction, the temperature difference generated in the semiconductor wafer 100 is suppressed to be small, and excessive thermal stress is prevented from being generated in the semiconductor wafer 100.
However, when the temperature difference generated in the semiconductor wafer 100 is small, such as when the transfer speed of the semiconductor wafer 100 is very low, the semiconductor wafer 100 does not necessarily need to be supported vertically. In this case, the semiconductor wafer 100 can be transported while being supported obliquely with respect to the transport direction by adjusting the positional relationship between the plurality of transport shafts 40. With this configuration, the cross-sectional area of the heating furnace 12 can be made relatively small.

Specific examples of the present invention have been described in detail above, but these are merely examples and do not limit the scope of the claims. The technology described in the claims includes various modifications and changes of the specific examples illustrated above.
For example, the configurations of the stable gas supply pipe 20, the reaction gas supply pipe 24, and the gas discharge pipe 28 can be changed as appropriate. FIG. 5 shows a modification thereof. As in the modification shown in FIG. 5, the stable gas supply pipe 20 connected to the nitrogen supply device 22 can be disposed so as to penetrate the wall portion of the heating furnace 12. In this case, a plurality of stable gas supply pipes 20 may be disposed over the entire heating furnace 12. Further, the reaction gas supply pipe 24 connected to the oxygen supply device 26 can also be disposed so as to penetrate the wall portion of the heating furnace 12. In this case, the plurality of reaction gas supply pipes 24 may be disposed only in the middle portion of the heating furnace 12. Further, the gas discharge pipe 28 can also be disposed so as to penetrate the wall portion of the heating furnace 12 at the center position of the heating furnace 12.

  In addition, a larger number of heaters 14 can be disposed in the heating furnace 12. FIG. 6 shows a modification thereof. In the modification shown in FIG. 6, six heaters 14 having a ring shape are arranged along the axial direction of the heating furnace 12. Furthermore, in this modification, the heater 14 is not provided in the section that continues to the carry-out port 12b. According to this configuration, the temperature gradient can be formed in seven sections along the transport direction including the section where the heater 14 is not present. Note that the number of heaters 14 provided in the heating furnace 12 can be reduced conversely. If at least one heater 14 is provided in the second section S2 (see FIG. 1), the temperature rises along the conveyance direction. The first section S1 (see FIG. 1), the second section S2 whose temperature is substantially constant along the transport direction, and the first section S3 where the temperature decreases along the transport direction can be realized.

  In addition, a plurality of spiral grooves 42 can be formed in the conveying shaft 40 in parallel. In other words, multiple spiral grooves 42 may be formed. When the spiral groove 42 is a single line, the semiconductor wafer 100 can be loaded and unloaded every time the conveyance shaft 40 rotates once. On the other hand, for example, when the spiral groove 42 has two strips, each time the transport shaft 40 makes a half rotation, one semiconductor wafer 100 can be loaded and unloaded.

  The technical elements described in this specification or the drawings exhibit technical usefulness alone or in various combinations, and are not limited to the combinations described in the claims at the time of filing. In addition, the technology illustrated in the present specification or the drawings achieves a plurality of objects at the same time, and has technical utility by achieving one of the objects.

The schematic diagram which shows the structure of the heat processing apparatus. II-II sectional view taken on the line in FIG. The figure which shows the temperature distribution in the conveyance direction in a heating furnace. The figure which expands and shows a conveyance shaft. The figure which shows the modification which deform | transformed the structure of the stable gas supply pipe | tube, the reactive gas supply pipe | tube, and the gas exhaust pipe. The figure which shows the modification which changed the structure of the heater.

Explanation of symbols

10: Heat treatment apparatus 12: Heating furnace 12a: Carrying inlet 12b: Carrying outlet 14: Heater 20: Stable gas supply pipe 22: Nitrogen supply apparatus 24: Reaction gas supply pipe 26: Oxygen supply apparatus 28: Gas discharge pipe 31: First Oxygen meter 32: second oxygen meter 40: transfer shaft 42: spiral groove 42a: bottom surface 48 of spiral groove 42: motor 100: semiconductor wafer 100e: outer peripheral edge

Claims (5)

A heat treatment apparatus for heat treating a semiconductor wafer,
A tubular heating furnace extending from a carry-in port capable of carrying in a semiconductor wafer to a carry-out port capable of carrying out a semiconductor wafer;
A plurality of transfer shafts extending from the carry-in port to the carry-out port through the heating furnace;
An actuator for rotating each of the plurality of transport shafts;
The plurality of transfer shafts are disposed in a positional relationship in contact with the outer peripheral edge of the semiconductor wafer, and each transfer shaft is formed with a spiral groove capable of receiving the outer peripheral edge of the semiconductor wafer. A heat treatment device characterized.   The heat treatment apparatus according to claim 1, wherein the lead of the spiral groove changes along the axial direction of the transport shaft.   The heat treatment apparatus according to claim 2, wherein the lead of the spiral groove is shortened in a range located in an intermediate section of the heating furnace. The plurality of conveying shafts are respectively formed with spiral grooves that rotate in the same direction,
The heat treatment apparatus according to any one of claims 1 to 3, wherein the actuator rotates a plurality of conveyance shafts in the same direction.   The heat treatment apparatus according to claim 4, wherein unevenness is formed on at least a part of the inner surface of the spiral groove.

Images