JP4509360B2 - Heat treatment method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
  The present inventionheatIt relates to the processing method.
[0002]
[Prior art]
A vertical heat treatment apparatus is known as one of semiconductor device manufacturing apparatuses. This heat treatment apparatus is of a batch type in which a large number of wafers are heat treated at once, and FIG. 11 shows a schematic view of an apparatus for performing low pressure CVD. Reference numeral 1 denotes a wafer boat which is a processing object holder. This wafer boat 1 holds a plurality of wafers W which are processing objects in a shelf shape, and an elevator (not shown), for example, a double-structure reaction tube 11 and It is carried into a reaction vessel composed of a cylindrical manifold 12. At this time, the reaction vessel is airtightly closed by the lid 10. On the other hand, a plurality of stages, for example, four stages of heaters 13 (13A to 13D) are provided outside the reaction vessel to divide the heat treatment atmosphere into a plurality of parts and perform temperature control (zone control). The inside is heated to a predetermined temperature and is reduced to a predetermined pressure by the exhaust pipe 14. Then, a film forming gas is supplied from the lower side of the reaction vessel through the gas supply pipe 15, is decomposed into thin film components and is deposited on the wafer W, and the remaining gas is supplied from the ceiling of the inner pipe 11a to the inner pipe 11a and the outer pipe. It descends the space between 11b.
[0003]
Under the wafer boat 1, for example, a thermal insulation unit 16 in which quartz wool or the like is accommodated in a cylindrical body made of quartz is interposed to insulate the atmosphere in which the wafer W is placed from the outside of the lid body 10 to keep the thermal insulation. Further, several dummy wafers W called side wafers are placed on the lower end side of the wafer boat 1 without placing the product wafers W.
[0004]
[Problems to be solved by the invention]
By the way, the heat capacity of the heat retaining unit 16 is set to be large so that the heat of the atmosphere in which the wafer W is placed is not released outside as much as possible. For this reason, when the temperature of the processing atmosphere is raised to the target processing temperature to stabilize the temperature, the temperature rise of the heat retaining unit 16 is delayed, and as a result, the time for the temperature to stabilize (recovery time) is long, resulting in a decrease in throughput. It is a factor of.
[0005]
Further, the heat retaining unit 16 blocks the heat flow between the processing atmosphere and the outside of the reaction vessel. However, since the lower part of the wafer placement area of the wafer boat 1 has a large amount of heat radiation, Side wafers (dummy wafers) are placed from the lowermost stage to several upper stages, and thus the area for placing the product wafer W must be narrowed.
[0006]
In order to solve such a problem, it is considered to provide a heat generating unit in the heat retaining unit 16, for example, to provide a planar heater on the upper surface of the heat retaining unit 16. By the way, the heaters 13A to 13D at each stage are temperature-controlled by the temperature controllers 17A to 17D, respectively. The temperature controllers 17A to 17D have temperature setting values from the recipe set by the main controller 18. Is given. When a heating element unit is provided, one dedicated temperature controller may be added. However, when adding to existing equipment, the recipe for the main controller 18 is usually equal to the number of heater stages currently present. In this example, only four steps can be set, and therefore, the operator must input the temperature set value outside the recipe.
[0007]
However, in such a method, it is difficult to find an optimum temperature set value at various process temperatures, and much labor is required. In order to be able to set the recipe for the temperature controller of the heating element unit in the main controller 18, the program must be recreated, which is not realistic.
[0008]
In addition, the present inventors are considering supplying a processing gas while slightly lowering the temperature when performing a heat treatment such as a film forming process. That is, since gas flows from the peripheral portion to the central portion of the wafer, the concentration of the film forming species at the peripheral portion is higher than the concentration of the film forming species at the central portion, and the film thickness of the peripheral portion of the wafer is larger than that of the central portion. It tends to grow. Therefore, if the processing gas is supplied while the wafer temperature is lowered, the heat radiation at the peripheral portion is larger than that at the central portion during the temperature drop, so the temperature at the peripheral portion is lower than that at the central portion, and the film thickness at the peripheral portion is central. It tends to be thinner than the portion, and this tendency and the previous tendency are offset, and as a result, the in-plane uniformity of the film thickness increases. Furthermore, depending on the type of heat treatment, processing with high in-plane uniformity may be performed by supplying a processing gas during the temperature rise and performing the heat treatment in a state where the temperature of the peripheral portion of the wafer W is higher than the central portion. .
[0009]
On the other hand, the purpose of providing the heat generating unit in the heat insulating unit is to increase the in-plane temperature uniformity of the wafer W near the bottom of the wafer boat 1, and therefore when the heat generating unit is provided, the temperature is lowered or increased. It was difficult to apply a process such as heat treatment.
[0010]
The present invention has been made under such circumstances, and an object of the present invention is to provide an existing apparatus for providing a heating element unit at the bottom of the reaction vessel separately from the heater surrounding the reaction vessel of the vertical heat treatment apparatus. It is an object of the present invention to provide a technique that can easily cope with a control system when adding a heating element unit to a heat treatment unit, and can also cope with heat treatment while raising or lowering the temperature in a reaction vessel.
[0011]
  The present invention allows a holder supported on a lid to hold a large number of objects to be processed in a shelf shape, and the holder is carried into a vertical reaction container from the lower side while the lid is used to react the reaction container. Airtightly seal the lower end ofAnd
  The inside of the reaction vessel is heated by a heater provided so as to surround the reaction vessel and divided into a plurality of stages, and a heating element unit provided between the lid and the holder. Performing a heat treatment on the object to be treated;
A set temperature is created from a temperature detection value of a first temperature detection unit provided in a region surrounded by a heater located at the lowest stage among the plurality of stages of heaters, and the set temperature and the heating element unit And a step of controlling the amount of heat generated by the heat generating unit in accordance with a deviation from a temperature detection value of a second temperature detection unit provided in the vicinity of Or b. It includes the requirements.
a. The step of performing heat treatment on the object to be processed is a step of performing heat treatment on the object to be processed by supplying a processing gas into the reaction container while lowering the temperature in the reaction container.
b. The step of performing heat treatment on the object to be processed is a step of performing heat treatment on the object to be processed by supplying a processing gas into the reaction container while raising the temperature in the reaction container.
[0012]
According to this invention, the heating element unit is provided on the lower side of the holder, and the set temperature is created from the temperature detection value of the first temperature detection unit provided in the area surrounded by the heater located at the lowermost stage. Therefore, the movement of the temperature of the heating element unit can be brought close to the movement of the conventional heat retaining unit. Therefore, the escape of heat from the heating atmosphere can be suppressed, the temperature can be quickly stabilized at the target temperature, and a recipe for the heating element unit need not be prepared, so that additional modifications to the existing apparatus are facilitated. Further, it is possible to cope with a case where the processing gas is supplied into the reaction vessel while the temperature in the reaction vessel is lowered or the temperature is raised to heat-treat the object to be processed.
[0013]
  In the present invention, a value obtained by subtracting the offset temperature from the temperature detection value of the first temperature detection unit is also used as the set temperature of the heating element unit.Good.The first temperature detection unit may be provided in the reaction vessel, or may be provided outside the reaction vessel. The heating element unit is configured, for example, by enclosing a resistance heating element with few metal impurities in ceramics.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
A vertical heat treatment apparatus according to an embodiment of the present invention will be described below. First, the structure of the apparatus will be briefly described with reference to FIGS. 1 to 3, and then a temperature control system will be described. 1 is a reaction tube having a double tube structure made of, for example, quartz made of an inner tube 2a and an outer tube 2b. A metal tubular manifold 21 is provided on the lower side of the reaction tube 2. It has been.
[0016]
The inner pipe 2 a has an upper end opened and is supported on the inner side of the manifold 21. The outer tube 2 b is closed at the upper end, and the lower end is airtightly joined to the upper end of the manifold 21. In this example, a reaction vessel is constituted by the inner tube 2a, the outer tube 2b, and the manifold 21. 21a is a base plate.
[0017]
In the reaction tube 2, a large number of, for example, 126 wafers W to be processed are placed on a wafer boat 22, which is a holder, in a horizontal state in a horizontal state with a vertical spacing. As shown in FIG. 2, the wafer boat 22 is configured by providing a plurality of support posts 22c between a top plate 22a and a bottom plate 22b, and forming grooves for holding the peripheral edge of the wafer W in the support posts 22c. The wafer boat 22 is held on the lid body 23 via an installation area of a heat retaining unit 31 described later. The lid 23 is mounted on a boat elevator 24 for loading and unloading the wafer boat 22 into and from the reaction tube 2. When the lid 23 is at the upper limit position, the lower end opening of the manifold 21, that is, the reaction tube 2 and the manifold 21 has the role of closing the lower end opening of the reaction vessel.
[0018]
Further, a heater 4 made of, for example, a resistance heating element is provided around the reaction tube 2 so as to surround the reaction tube 2. As an example of the heater 4, for example, a linear flexible carbon wire formed by weaving a plurality of bundles of thin high-purity carbon fibers is used in ceramics such as a transparent quartz tube. And the like that are enclosed in a container. In this example, the heat treatment atmosphere in the reaction tube 2 is divided into a plurality of, for example, four, and the heater 4 is divided into four stages (4-1 to 4-4) corresponding to each divided region, as described later. Temperature zone control (temperature control of divided areas) is performed. Although not shown in FIG. 1, a heat insulating layer is provided around the heater 4, and an exterior body is further provided on the outer side thereof, and these constitute a heating furnace 20 (see FIG. 2).
[0019]
A plurality of gas supply pipes are provided around the manifold 21 so that a plurality of process gases can be supplied into the inner pipe 2a. In FIG. 1, one of the gas supply pipes 25 is shown, and this gas supply pipe 25 is connected to a gas supply source 26 via a valve V1, a flow meter MFC, and a valve V2. Further, an exhaust pipe 27 is connected to the manifold 21 so as to be able to exhaust air from the space between the inner pipe 2a and the outer pipe 2b, and the inside of the reaction pipe 2 can be maintained in a predetermined reduced pressure atmosphere by a vacuum pump 28. It has become.
[0020]
Briefly describing the heat retaining unit 31 and the parts related thereto, the heat retaining unit 31 includes a heat insulating unit 32 made of, for example, quartz, and each heat insulating unit 32 has a circular upper surface as shown in FIG. A portion 33 and a bottom plate portion 34, three supporting column portions 35 which are provided between the upper surface portion 33 and the bottom plate portion 34 and are provided at intervals in the circumferential direction; And quartz fins 36 (see FIG. 1), which are heat insulating members inserted in multiple stages.
[0021]
Further, a first protective tube 37 and a second protective tube 38 are provided between the upper surface portion 33 and the bottom surface portion 34 of the heat insulating unit 32 at intervals in the circumferential direction. Both ends open to the upper surface portion 33 and the bottom surface portion 34, respectively. For example, a planar heating element unit 5 is provided on the upper surface portion of the heat insulating unit 32. The heating element unit 5 is configured by enclosing a resistance heating element with few metal impurities in ceramics such as quartz. For example, as shown in FIG. 4, a quartz disk-shaped body having a thickness of about 8 mm. A heater wire 52 made of a high-purity carbon material 51 is arranged in a spiral shape.
[0022]
As shown in FIG. 3, a third protective tube 53 is connected to the lower surface of the peripheral edge of the heating element unit 5, and the power supply line 54 for supplying power to the heater wire 52 is shown in FIG. As shown in FIG. 3, the third protective tube 53 is connected to the connection portion, and is inserted into the protective tube 53 from there. The third protective tube 53 is inserted into the first protective tube 37 opened in the upper surface portion 33 of the heat insulating unit 32, and further penetrates the lid body 23 to the lower surface side of the lid body 23. Is fixed. Therefore, the third protective tube 53 also serves as a support for the heating element unit 5. Further, a temperature detection unit 55 made of a thermocouple is inserted into the second protective tube 38, and its tip is bent into an L shape to detect the temperature of the heating element unit 5 below. Located on the side. In addition, holes 33a, 34a, 36a (see FIG. 1) and 5a through which the rotary shaft 29 passes are formed in the center of the upper surface portion 33 and the bottom surface portion 34 of the heat insulation unit 32, the quartz fin 36, and the heating element unit 5, respectively. The wafer boat 22 is rotated by the motor M provided on the boat elevator 24 via the rotating shaft 29.
[0023]
Next, a control system for controlling the temperature in the reaction tube 2 will be described with reference to FIGS. In this embodiment, the temperature controllers 6 (6-1 to 6-4) and the power control units 7 (7-1 to 7-1) correspond to the heaters 4 (4-1 to 4-4) of the respective stages. 7-4) and temperature detectors TC1 to TC4 made of, for example, thermocouples for detecting the temperatures of the heaters 4-1 to 4-4, respectively. Although the temperature detectors TC1 to TC4 are described in a simplified manner in FIG. 5, the temperature detectors TC1 to TC4 are actually arranged between the heaters 4-1 to 4-4 and the reaction tube 2 from outside the heating furnace 20 shown in FIG. Is plugged in. In the temperature controllers 6-1 to 6-4, there are the temperature set values set by the recipe in the host controller (not shown) and the temperature detection values detected by the temperature detectors TC1 to TC4. A control signal corresponding to the deviation between the temperature set value and the temperature detection value is output to the power control unit 7 (7-1 to 7-4). The power control units 7-1 to 7-4 are configured to control the power supplied to the heaters 4-1 to 4-4 by phase control of semiconductor elements such as thyristors.
[0024]
Although not shown in FIGS. 1 and 5, as the temperature detection unit, in addition to the above-described temperature detection units (external temperature detection units) TC <b> 1 to TC <b> 4 provided outside the reaction tube 2, Temperature detectors (internal temperature detectors) are provided in the heating regions of the heaters 4-1 to 4-4, and the temperature controllers 6-1 to 6-4 are actually In addition to the temperature detection values of the external temperature detection units TC1 to TC4, the temperature detection value of the internal temperature detection unit is also taken in for temperature control.
[0025]
Further, in this embodiment, a temperature controller 6 (6-5) and a power control unit 7 (7-5) are provided corresponding to the heat generating unit 5 on the lower side of the wafer boat 22. The temperature controller 6 (6-5) receives the temperature detection value and the temperature set value detected by the temperature detection unit 55 described above. In this example, the temperature detection value of the temperature detection unit TC4 is used. The temperature detectors TC4 and 55 correspond to the first temperature detector and the second temperature detector in the claims, respectively. The position of the temperature detector TC4 is not accurate due to the limitation of the description area in FIG. 5, but is actually higher than the lowermost wafer W on the wafer board 22, for example.
[0026]
FIG. 6 is a block diagram showing the configuration of the temperature controller 6-5. Reference numeral 81 in FIG. 6 denotes an offset temperature table, which stores the relationship between the temperature detection value of the temperature detection unit TC4 and the offset temperature, and reads the offset temperature corresponding to the temperature detection value. A deviation circuit unit 82 outputs a value obtained by subtracting the offset temperature from the temperature detection value. A delay time table 83 stores the relationship between the temperature detection value of the temperature detection unit TC4 and the delay time, and reads the delay time corresponding to the temperature detection value. Reference numeral 84 denotes a delay circuit unit composed of, for example, a first-order delay circuit unit or a dead time circuit unit that delays the output of the deviation circuit unit 82 by the delay time.
[0027]
These components create the set temperature of the heating element unit 5 based on the temperature detection value of the temperature detection unit TC4, and here, the meaning thereof will be mentioned. The temperature of a heat insulating unit that does not include a heating element unit as in the prior art, for example, the temperature of a heat insulating cylinder, is composed of the relationship between heat transfer and heat radiation with the bottom zone temperature (the temperature surrounded by the heater 4-4). When the temperature control is performed by associating the heating element unit 5 with the bottom zone temperature, the heating element unit 5 has a heat insulation performance for preventing escape of heat from the heated wafer W located in the lowest zone. It can be regarded as a thermal insulation unit with good thermal insulation performance. In this embodiment, the control system is assembled from this point of view, but the temperature of the normal heat retaining unit is less than the temperature of the bottom zone heater (lowermost heater) 4-4 due to heat escape. In order to make a temperature difference between the temperature of the lowermost heater 4-4 and the temperature of the heating element unit 5, an offset temperature is added to the temperature detection value of the temperature detection unit TC4. Is added. In addition, since a normal heat retaining unit is warmed by the heat of the heater, the temperature rises and falls slightly later, so a delay circuit unit 84 is provided to delay the temperature detection value of the temperature detection unit TC4, which will be described later. To the PID arithmetic circuit section.
[0028]
Further, when the wafer boat 22 is outside the reaction vessel or during loading or unloading, the heating element unit 5 is set to a temperature lower than the bottom zone temperature (the temperature surrounded by the heater 4-4). The temperature controller 6-5 includes a standby temperature table 85 in which a plurality of set temperatures for standby are prepared so that the temperature can be lowered. The standby temperature is not limited to a plurality of preparations, but an apparatus that handles a plurality of process recipes may require a plurality of standby temperatures. In this example, a standby temperature table 85 is prepared, for example, the temperature The standby temperature is output based on a signal from a temperature selection unit 86 provided outside the controller 4-4.
[0029]
The vertical heat treatment apparatus includes an open / close sensor 87, a signal selection unit 88, and a PID control circuit unit 89 that detect whether the lid body 23 is open or closed. When the sensor 87 detects the open state of the lid 23, the signal selection unit 88 uses the detection signal as a standby temperature output from the standby temperature table 85 to set the heating element unit 5 as the set temperature of the PID control circuit. When the open / close sensor 87 detects that the lid 23 is closed, the signal selection unit 88 inputs the set temperature from the delay circuit unit 84 to the PID control circuit unit 89 based on the detection signal. It is configured. The PID control circuit unit 89 receives the set temperature from the signal selection unit 88 and the temperature detection value of the heating element unit 5 from the temperature detection unit 55, performs PID calculation based on the deviation, and the calculation result Is output as a control signal to the power control unit 7 (7-5) shown in FIG. An IPD control unit or a modern control unit may be used instead of the PID control circuit unit.
[0030]
Next, the operation of the above embodiment will be described. Here, an example of forming a silicon nitride film by a CVD process is given as an example of a specific process. First, a predetermined number of wafers W to be processed are held in a shelf shape on the wafer boat 22 and the boat elevator 24 is moved up to be loaded (loaded) into the reaction vessel. When the wafer board 22 is not loaded into the reaction vessel, that is, when the wafer W is being transferred to the wafer board 22 or during loading, the opening / closing sensor 87 opens the lid. Since a detection signal indicating that the body 23 is open is output to the signal selection unit 88, the standby temperature output from the standby temperature table 85 is selected as the setting signal for the heating element unit 5, and this standby temperature is selected. Based on the above, the temperature of the heating element unit 5 is controlled.
[0031]
When the wafer boat 22 is loaded, the inside of the reaction tube 2 is maintained at about 600 ° C., for example. The wafer boat 22 is loaded and the lower end opening of the reaction vessel (specifically, the lower end opening of the manifold 21) is covered. After being blocked by the body 23, the temperature inside the reaction tube 2 is stabilized, and then the reaction temperature inside the reaction tube 2 is increased by the heater 4 (4-1 to 4-4) and the heating element unit 5, for example, 760 ° C. And the inside of the reaction vessel is evacuated to a predetermined degree of vacuum by the vacuum pump 28 through the exhaust pipe 27. Although the inside of the reaction tube 2 is also heated by the heating element unit 5, this heating is referred to as heat insulation that prevents heat escape from the wafer W located in the lowest zone, as described above, rather than active heating. The meaning is greater.
[0032]
When the lid 23 is closed, a detection signal indicating that the lid 23 is closed is output from the open / close sensor 87 to the signal selection unit 88, so that the set temperature of the heating element unit 5 is the delay circuit unit 84. The output signal from is used. That is, in this example, the temperature detection value of the temperature detection unit TC4 used for temperature control of the lowermost heater 4 (4-4) is set as a set temperature, and more specifically, an offset temperature corresponding to this temperature detection value is set as the temperature. The temperature value subtracted from the detected value is delayed by a predetermined time and used as the set temperature of the heating element unit 5.
[0033]
In this embodiment, the offset temperature can be changed according to the temperature detection value of the temperature detection unit TC4, and the delay time by the delay circuit unit 84 can also be changed according to the temperature detection value. 7 is a fixed value, for example, FIG. 7 shows the temperature of the heating element unit 5 when the offset temperature is 50 ° C. and the delay time is 50 seconds. In FIG. 7, the solid line a is the set temperature of the lowermost heater 4-4, the chain line b is the temperature of the wafer W in the heating area (covering range) by the heater 4-4, and the dotted line c is the heating element unit 5. Temperature.
[0034]
As can be seen from FIG. 7, during the loading period, as the wafer boat 22 is carried into the reaction vessel, the temperature of the wafer W (the wafer W temperature described here is the wafer in the heating region of the heater 4-4). After the temperature is increased and loading is completed, the temperature stabilizes near the set temperature. Next, during the temperature raising period, the temperature of the wafer W rises with a delay after the set temperature rises and stabilizes at the process temperature (760 ° C.). On the other hand, the temperature of the heating element unit 5 also moves in the same manner as the temperature of the wafer W, but rises after the temperature rise of the wafer W and stabilizes at a temperature lower by the temperature corresponding to the offset temperature. . In this example, since the set temperature of the heating element unit 5 is set with a delay with respect to the temperature of the external temperature detector TC4, the delay time described in FIG. 7 is strictly the delay time set by the circuit of FIG. Smaller than.
[0035]
Thus, after the inside of the reaction tube 2 is stabilized at a process temperature, for example, 760 ° C., a processing gas, for example, dichlorosilane (SiH 2 Cl 2) gas and ammonia (NH 3) gas, are supplied to two gas supply tubes 25 (as described above, 1 in FIG. (Only the book is shown) and the pressure inside the reaction vessel is maintained at a predetermined degree of vacuum while being supplied into the reaction vessel, and a silicon nitride film is formed on the surface of the wafer W. At this time, the wafer boat 22 is rotated by the motor M. Thus, after the silicon nitride film is formed for a predetermined time, the supply of the processing gas is stopped, the temperature in the reaction tube 2 is lowered to 600 ° C., and the wafer boat 22 is unloaded (unrolled). Do).
[0036]
According to the above-described embodiment, since the temperature set value of the heating element unit 5 is created from the temperature of the region surrounded by the heater 4-4, for example, the delay time, the offset temperature, the PID control circuit unit 89 By adjusting the parameters, etc., the movement of the temperature of the heating element unit 5 can be brought close to the movement of a conventional heat insulation unit that has been conventionally used (a heat insulation unit that does not include a heating element unit). Furthermore, the heat insulation performance can be improved and the temperature recovery performance can be improved as compared with a normal heat retaining unit, and the function of the heating element unit can be exhibited as described in the section of the problem to be solved by the invention. Further, since it is not necessary to create a recipe for the heating element unit 5, additional modification to the existing vertical heat treatment apparatus is facilitated.
[0037]
Here, as mentioned in the item of the problem to be solved by the present invention, an example in which film formation is performed while the temperature is lowered will be described. FIG. 8 shows a profile of the set temperature of the heater 4. In this case, for example, the temperature inside the reaction tube 2 is raised to a temperature of 770 ° C., and then the power supplied to the heater 4 is reduced or turned off to lower the temperature inside the reaction tube 2 to 750 ° C. A silicon nitride film is formed on the wafer W by supplying dichlorosilane gas and ammonia gas. Next, the supply of the processing gas is stopped and the temperature in the reaction tube 2 is raised to 770 ° C. Thus, the temperature rise and fall is repeated, for example, film formation is performed three times during the temperature drop.
[0038]
FIG. 9 is a temperature change for a part of the series of operations of FIG. 8, where solid line a is the set temperature of the lower heater 4-4, and chain line b is the heating region ( The temperature of the wafer W within the (handling range) and the dotted line c are the temperatures of the heating element unit 5. In this example, the offset temperature is set to zero when the temperature detection value of the temperature detection unit TC4 is set to the set temperature of the heating element unit 5.
[0039]
If the film is formed during the temperature decrease in this way, the temperature of the peripheral portion of the wafer W becomes lower than the central portion during the temperature decrease as described above, so that the film thickness of the peripheral portion tends to be thinner than the central portion. For this reason, the in-plane non-uniformity of the film thickness based on the fact that there are more active species in the peripheral portion than in the central portion is offset and the in-plane uniformity of the film thickness is increased. As can be seen from FIG. 9, the temperature of the heating element unit 5 is the same as that of a normal heat retaining unit. Therefore, the temperature at the peripheral edge of the wafer W is lower than the temperature at the center during the temperature decrease. it can. In this example, the offset temperature is zero, but it is not limited to zero. Also, depending on the process, the heat treatment during the temperature rise may result in a treatment with higher in-plane uniformity. Therefore, in the present invention, the heat treatment may be performed during the temperature rise. In this case, the temperature of the peripheral portion of the wafer W is higher than that of the central portion, but it can be dealt with while using the heating element unit 5 for the same reason.
[0040]
In the above description, the temperature detection value of the temperature detection unit TC4 is handled as the temperature setting value of the heating element unit 5, but this temperature setting value is a temperature corresponding to the heat generation amount of the lowermost heater 4-4. As described above, the temperature detection value of the internal temperature detection unit provided in the reaction tube 2 may be used as described above, or the temperature read by the temperature controller 6-4 may be used.
[0041]
Furthermore, in the present invention, a planar heating element unit (top plate heater) 9 having the same configuration as that of the heating element unit 5 is provided above the reaction tube 2 as shown in FIG. The temperature controller 6 detects the temperature of the area surrounded by the heater 4-1, for example, the temperature controller 6 in the same manner as the setting temperature of the heating element unit 5 described above from the temperature detection value of the temperature detection unit TC1. In (6-6), the set temperature of the top heater 9 is created, and based on this set temperature and the temperature detection value of the temperature detector 91 that detects the temperature of the top heater 9, the power You may make it output the control signal of the control part 7 (7-6). The temperature controller 6-6 has the same configuration as the temperature controller 6-5, but does not have a configuration in which the setting signal is switched by opening and closing the lid 23.
[0042]
If the top plate heater 9 is provided and such temperature control is performed, heat radiation from the ceiling portion of the heating furnace 20 can be suppressed, and it can be easily applied to existing devices, and the temperature of the top plate heater 9 can be controlled. Since the same movement as that of a conventional heat insulation unit such as a heat insulation cylinder is performed, it is possible to cope with a case where heat treatment is performed while lowering or raising the temperature.
[0043]
The present invention can be applied not only to a low pressure CVD apparatus but also to a so-called oxidation and diffusion furnace.
[0044]
【The invention's effect】
As described above, according to the present invention, since the heating element unit is provided on the lower side of the holder in the vertical heat treatment apparatus, a high heat insulating effect is obtained, and the region surrounded by the heater located at the lowermost stage Since the set temperature is created from the temperature detection value of the temperature detector provided in the control unit, it is easy to handle the control system when adding a heating element unit to an existing device, and the temperature inside the reaction vessel is increased. It can also be used for heat treatment while the temperature is being lowered or lowered.
[Brief description of the drawings]
FIG. 1 is a longitudinal side view showing a structure of a vertical heat treatment apparatus according to an embodiment of the present invention.
FIG. 2 is a perspective view showing an appearance of the vertical heat treatment apparatus.
FIG. 3 is an exploded perspective view showing a part of a heat retaining unit used in the vertical heat treatment apparatus.
FIG. 4 is a sectional view and a plan view showing a heating element unit used in the vertical heat treatment apparatus.
FIG. 5 is a block diagram showing a temperature control system in the present embodiment.
FIG. 6 is a block diagram showing a temperature controller of a heating element unit in the present embodiment.
FIG. 7 is a characteristic diagram showing an example of temporal changes in heater set temperature, wafer temperature, and heating element unit temperature.
FIG. 8 is a characteristic diagram showing temporal changes in the set temperature of the heater when heat treatment is performed while the temperature in the reaction tube is lowered.
FIG. 9 is a characteristic diagram showing another example of temporal changes in the heater set temperature, the wafer temperature, and the heating element unit temperature.
FIG. 10 is a block diagram showing a temperature control system in another embodiment of the present invention.
FIG. 11 is a vertical side view showing a conventional vertical heat treatment apparatus.
[Explanation of symbols]
2 reaction tubes
21 Manifold
23 Lid
W Semiconductor wafer
25 Gas supply pipe
27 Exhaust pipe
31 Thermal insulation unit
32 Thermal insulation unit
4 (4-1 to 4-4) Heater
TC1 to TC4 Temperature detector
5 Heating unit
55 Temperature detector
6 (6-1 to 6-6) Temperature controller
7 (7-1 to 7-6) Power control unit
81 Offset temperature table
82 Adder
83 Delay time table
84 Delay circuit
85 Standby temperature table
87 Open / close sensor
88 Signal selector
89 PID control circuit

Claims (3)

A plurality of objects to be processed are held in a shelf shape on a holder supported on a lid, and the holder is carried into a vertical reaction container from below and the lower end of the reaction container is hermetically sealed by the lid. The process of closing
The inside of the reaction vessel is heated by a heater provided so as to surround the reaction vessel and divided into a plurality of stages, and a heating element unit provided between the lid and the holder. Performing a heat treatment on the object to be treated;
A set temperature is created from a temperature detection value of a first temperature detection unit provided in a region surrounded by a heater located at the lowest stage among the plurality of stages of heaters, and the set temperature and the heating element unit A step of controlling the amount of heat generated by the heating element unit according to a deviation from a temperature detection value of a second temperature detection unit provided in the vicinity of
The step of performing heat treatment on the object to be processed is a step of performing heat treatment on the object to be processed by supplying a processing gas into the reaction container while lowering the temperature in the reaction container. Method. A plurality of objects to be processed are held in a shelf shape on a holder supported on a lid, and the holder is carried into a vertical reaction container from below and the lower end of the reaction container is hermetically sealed by the lid. The process of closing
The inside of the reaction vessel is heated by a heater provided so as to surround the reaction vessel and divided into a plurality of stages, and a heating element unit provided between the lid and the holder. Performing a heat treatment on the object to be treated;
A set temperature is created from a temperature detection value of a first temperature detection unit provided in a region surrounded by a heater located at the lowest stage among the plurality of stages of heaters, and the set temperature and the heating element unit A step of controlling the amount of heat generated by the heating element unit according to a deviation from a temperature detection value of a second temperature detection unit provided in the vicinity of
The step of performing the heat treatment on the object to be processed is a step of performing a heat treatment on the object to be processed by supplying a processing gas into the reaction container while increasing the temperature in the reaction container. Heat treatment method. The heat treatment method according to claim 1 or 2 , wherein a value obtained by subtracting an offset temperature from a temperature detection value of the first temperature detection unit is set as a set temperature of the heating element unit.

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