KR20100113494A - Placing table apparatus, processing apparatus and temperature control method - Google Patents

Abstract

Placement table 26 for arranging to-be-processed object W on an upper surface, Heating mechanism 30 which has a some heating heater part provided for each heating zone partitioned concentrically to the placing table 26, Placement table A leg portion 28 connected to the central portion of the center 26 and supporting the mounting table horizontally in an upright position, and a temperature measuring portion 38 provided in correspondence with the heating zones of the innermost circumferences in the plurality of heating zones; Based on the measured value of the temperature measuring part 38, the feedback control of the temperature of the heating heater part of the innermost periphery is carried out, and the heating of the innermost perimeter determined so that the temperature difference between heating zones may become a range which does not damage the mounting table 26. The power supply control part 42 which controls supply power to another heating heater part with a safe supply electric power ratio with respect to a heater part is provided.

Description

Batch Unit, Treatment Unit and Temperature Control Method {PLACING TABLE APPARATUS, PROCESSING APPARATUS AND TEMPERATURE CONTROL METHOD}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a processing apparatus for performing a heat treatment such as a film forming process on a target object such as a semiconductor wafer, a mounting table apparatus used for this, and a temperature control method.

Generally, in order to manufacture a semiconductor integrated circuit, various processes, such as a film-forming process, an etching process, a thermal-diffusion process, and a modification process, are performed repeatedly with respect to to-be-processed objects, such as a semiconductor wafer.

For example, a single wafer type processing apparatus which heat-treats a semiconductor wafer for one sheet will be described as an example. The arrangement in which a resistance heating heater made of, for example, molybdenum wire is incorporated in a processing container capable of vacuum state The stand is attached to the upper end of the leg standing up from the bottom of the container, and the semiconductor wafer is placed on the mounting table. Then, while the semiconductor wafer is placed on the mounting table in this manner, while the predetermined processing gas flows into the processing container, the inside of the semiconductor wafer is maintained in a predetermined reduced pressure atmosphere, and at the same time, the resistance heating heater is driven to heat the semiconductor wafer to a predetermined temperature. The predetermined | prescribed process, such as a film-forming process, is performed.

In general, aluminum alloys have been generally used mainly for the mounting table and the legs, but as is well known, since semiconductor wafers are very weak to various metal contaminations, the degree of metal contamination is less than that of the aluminum alloys. It is proposed to use an excellent ceramic material such as AlN as a mounting table or a leg portion (for example, JP-A-128668 and JP-A-6-252055).

In these patent documents, one hollow leg part is connected to the center of the back surface of a mounting table, and necessary wirings, such as a feeder for a resistance heating heater, are accommodated in the hollow leg part. Then, a thermocouple is provided on the lower surface side of the center of the mounting table, and two heating zones of concentric type that can be independently controlled from each other are provided by dividing the resistance heating heater of the mounting table into a plurality of, for example, two, The temperature of each said heating zone is controlled individually based on the measured value of the said thermocouple provided in the center of a mounting table.

Specifically, for example, in the case of forming a film, for example, the temperature distribution at which the in-plane uniformity of the film thickness is best varies depending on the process temperature for heating the semiconductor wafer. Obtaining the current ratio or the voltage ratio between the heaters which becomes the optimum temperature distribution in advance, and when processing the actual product wafer, the feedback is given based on the measured value in the thermocouple regarding the temperature of the heating zone around the innermost circumference. Control the temperature of the other outer heating zone, and supplying electric power based on a current ratio or a voltage ratio with respect to the heater of the innermost circumferential heating zone previously found corresponding to the process temperature, so-called open loop. It is supposed to be controlled.

By the way, although the mounting table and the leg part which support this are made of ceramic materials, such as AlN (aluminum nitride) as mentioned above, this ceramic material is a brittle material, and the heat | fever which arises due to the temperature distribution between the inner and outer peripheries in a mounting table is mentioned. This mounting table may be easily damaged by stress. In particular, in the method of controlling the temperature of the heating zone (heater) of the inner and outer circumference of the mounting table by the current ratio and the voltage ratio depending on the process temperature, there is a problem that the mounting table made of ceramics is easily damaged.

SUMMARY OF THE INVENTION An object of the present invention is to provide a mounting table apparatus that is hardly damaged by thermal stress when the object to be processed is disposed on the mounting table and to be heated, and a processing device equipped with such a mounting table device.

Another object of the present invention is to provide a temperature control method in which the mounting table is not easily damaged by thermal stress when the object to be processed is placed on the mounting table and heated.

Another object of the present invention is to provide a storage medium storing a program for executing such a temperature control method.

As a result of intensive studies on the breakage of the placement table made of ceramic material, the inventors have compared the temperature difference between the inner and outer circumferences that cause the breakage in the case of the temperature control by the power ratio, as compared with the temperature control by the current ratio or the voltage ratio. The present invention has been accomplished by finding that it can be suppressed small.

That is, according to the first aspect of the present invention, there is provided a heating mechanism including a mounting table for arranging a target object, a plurality of heating heaters provided for each of the plurality of heating zones concentrically partitioned on the mounting table, and the mounting table. The innermost side based on the leg part which is connected to the center part, and horizontally supports the said mounting table, the temperature measuring part provided corresponding to the heating zone of the innermost periphery in the said some heating zone, and the measured value of the said temperature measuring part. Feedback-controlling the temperature of the circumferential heating heater part, and having a safety supply power ratio to the heating heater part of the innermost circumference, determined so that the temperature difference between the heating zones is such that the placement table is not damaged. There is provided a pedestal device comprising a power supply control unit for controlling supply power.

Thus, in controlling the temperature of the mounting table which arrange | positions a to-be-processed object, it feedback-controls the temperature of the said heating heater part of the innermost periphery based on the measured value of a temperature measuring part, and arrange | positions the temperature difference of each heating zone (heater) of a mounting table. By controlling the power supply to the other heating heater part with the power ratio (safety supply power ratio) with respect to the heating heater part of the innermost periphery determined so that it might become the range which does not damage a stand | base, the temperature difference which arises between the inner and outer peripheries of a mounting table is suppressed, and arrangement | positioning It is possible to prevent the stand from being damaged by the stress.

In this case, the said safety supply power ratio can be set so that the temperature of the heating zone around the innermost periphery of the said mounting table may become lowest, and specifically, the said safety supply power ratio corresponds to the to-be-processed object of 300 mm in diameter. When doing so, it can set to the electric power ratio in which the temperature difference between the said innermost periphery and the heating zone of an outermost periphery becomes 33 degrees C or less.

Moreover, at the time of the temperature increase and the temperature of the said mounting base, the said power control part has the temperature of the heating zone of the innermost periphery lower than the temperature of the heating zone of the outermost perimeter at the time of the temperature increase and the temperature of the said mounting base. It is desirable to control so as not to lose.

In addition, the said power supply control part heats up the temperature of the heating zone of the innermost periphery rather than the outermost periphery at the time of the temperature increase of the said mounting table, and, if it reaches | attains the set temperature, supplies the power supply to each said heating heater part to the said safety supply. It is desirable to control to sequentially approach the power ratio. Moreover, as said temperature measuring part, what has a thermocouple typically can be used.

Moreover, as at least one of the said mounting table and the said leg part, what consists of a ceramic material can be used.

According to a second aspect of the present invention, there is provided a processing apparatus for performing a predetermined heat treatment on a target object, comprising: a processing container configured to exhaust an internal atmosphere; a gas supply mechanism for supplying a gas required in the processing container; And a mounting table device for arranging the ribs, wherein the mounting table device includes a mounting table for placing the object to be processed and a plurality of heating heaters provided for each of the plurality of heating zones concentrically partitioned on the mounting table. A measurement unit connected to a mechanism, a central portion of the mounting table, the leg portion supporting the mounting table horizontally, a temperature measuring section provided in correspondence with the heating zones of the innermost periphery in the plurality of heating zones, and the measured value of the temperature measuring section. Based on the feedback control of the temperature of the heating heater portion of the innermost circumference, the temperature difference between the heating zones does not damage the mounting table There is provided a processing apparatus including a power supply control section for controlling supply power to the other heating heater section at a safe supply power ratio to the heating heater section around the innermost circumference, determined to be in the range.

According to a third aspect of the present invention, a plurality of heating heaters are disposed on a mounting table provided in a processing container capable of evacuating an internal atmosphere, and are provided for the plurality of heating zones concentrically partitioned on the mounting table. A method of controlling the temperature of the object to be processed by controlling a heating mechanism including a portion, the method comprising: measuring a temperature of a heating zone of the innermost circumference in the plurality of heating zones, and based on the measured temperature, The other heating heater with a safety supply power ratio to the heating heater part of the innermost circumference determined such that the heating heater part is controlled by feedback control to be a set temperature and the temperature difference between the heating zones is within a range such that the placement table is not damaged. A temperature control method is provided that includes controlling the power supply to the unit.

From the said 3rd viewpoint, at the time of temperature rising of the said mounting table, it is preferable to keep the temperature of the heating zone of the innermost periphery not to become lower than the temperature of the heating zone of the outermost perimeter more than predetermined temperature. Moreover, it is preferable to keep the temperature of the heating zone of the innermost periphery not lower than the predetermined temperature difference more than the heating zone temperature of the outermost periphery at the time of the temperature drop of the said mounting table.

According to the fourth aspect of the present invention, a plurality of heatings are provided for each of a plurality of heating zones arranged concentrically on the mounting table and arranged on the mounting table provided in the processing container configured to exhaust the internal atmosphere. In controlling a heating mechanism including a heater unit, controlling the temperature of the object to be processed, and performing a predetermined treatment on the object to be processed, the temperature of the heating zone around the innermost circumference in the plurality of heating zones And controlling the heating heater of the innermost circumference based on the measured temperature to control the heating heater to be a set temperature, and determining that the temperature difference between the heating zones is such that the placement table is not damaged. Controlling the supply power to the other heating heater with a safe supply power ratio to the heater; A storage medium is provided which stores a program for controlling a processing device in a computer so as to perform the temperature control method.

1 is a schematic cross-sectional view showing a processing apparatus according to an embodiment of the present invention.
It is a top view which shows the heating mechanism provided in the mounting table of the mounting apparatus of the processing apparatus of FIG.
It is a figure which shows typically the relationship of the process gas concentration and temperature distribution in the radial direction of a semiconductor wafer.
4 is a graph showing an example of the relationship between supply power ratio and film thickness variation.
FIG. 5 is a diagram showing the result of the presence or absence of damage to the mounting table when the power to the outer zone heater is controlled by a predetermined power supply ratio to actually perform the film formation process.
6 is a diagram illustrating a range of allowable power supply ratios depending on process temperatures.
7A is a graph showing changes in heater temperature and operation amount when the conventional voltage ratio is controlled.
7B is a graph showing changes in heater temperature and operation amount when the power ratio of the present invention is controlled.
It is a graph for demonstrating an example of the change state of the temperature of a heater and supply power ratio at the time of temperature rising of a mounting table.

EMBODIMENT OF THE INVENTION Below, embodiment of this invention is described with reference to an accompanying drawing.

BRIEF DESCRIPTION OF THE DRAWINGS The schematic sectional drawing which shows the processing apparatus which concerns on one Embodiment of this invention, and FIG. 2 is a top view which shows the heating mechanism provided in the mounting table of the mounting apparatus of the processing apparatus. Here, the case where the film-forming process is performed by CVD with respect to the semiconductor wafer which is a to-be-processed object is demonstrated as an example.

As shown, this processing apparatus 2 has the processing container 4 shape | molded to cylindrical shape by nickel, nickel alloy, or aluminum alloy, for example. The ceiling of this processing container 4 is provided with a shower head portion 6 having a plurality of gas ejection holes 6A and 6B in the lower surface as a gas supply mechanism, whereby, for example, film forming gas is used as the processing gas. It is possible to introduce into the processing space S in the processing container 4. The shower head part 6 is divided into two gas spaces 8A and 8B, for example, and the gas ejection holes 6A and 6B communicate with each gas space 8A and 8B, respectively. It is a so-called postmix type which can mix two gases for the first time in (S).

The whole shower head part 6 is formed with nickel, nickel alloy, aluminum alloy etc., for example. The ceiling of the processing container 4 having the shower head portion 6 is attached to the upper end of the side wall of the processing container 4 through a seal member 10 made of, for example, an O-ring, so that the inside of the processing container 4 can be installed. It is intended to maintain confidentiality.

In the sidewall of the processing container 4, a carry-out port 12 for carrying in and out of the semiconductor wafer W as an object to be processed is formed, and a gate valve 14 is provided to open and close it. . A load lock chamber or a transfer chamber (not shown) is connected to the gate valve 14.

Moreover, the recessed part 17 recessed in the downward direction is formed in the center part side of the bottom part 16 of this processing container 4, and the inside of this recessed part 17 becomes the exhaust space 18. As shown in FIG. And the exhaust port 20 is formed in the lower side wall of the recessed part 17 which defines this exhaust space 18. The exhaust port 20 is connected to a vacuum exhaust system 22 in which a pressure control valve and a vacuum pump not shown are interposed, and the vacuum exhaust system 22 is in a vacuum state in advance. It is to be maintained at a predetermined pressure.

In the processing container 4, a mounting table device 24 for placing a semiconductor wafer as an object to be processed is provided. The mounting table apparatus 24 is connected to a center of the lower surface of the mounting table 26 and extends downward while the mounting table 26 actually arranges the wafer W on its upper surface. It has a leg 28 to support. The leg portion 28 is supported by the bottom portion 16A of the concave portion 17 whose lower end defines the exhaust space 18. The leg 28 has a hollow inside, that is, a cylindrical body, and has an open bottom. The mounting table 26 and the leg portion 28 are both made of ceramic material such as AlN. One of these may be formed of a ceramic material.

On the upper side of the mounting table 26, a resistance heating heater 30 is embedded as a heating mechanism for heating the wafer W disposed thereon. The resistance heating heater 30 is made of, for example, molybdenum wire, and as shown in FIG. 2, the resistance heating heater 30 is concentrically formed here with the inner zone heater 32A and the outer zone heater 32B. It is divided into two and two heating zones of an inner heating zone and an outer heating zone are formed, and heating temperature can be controlled for every zone. And a ceramic heater is comprised by the mounting base 26 and the resistance heating heater 30 which consist of ceramic materials.

In addition, this zone number is not specifically limited, Three or more zones may be sufficient.

The connecting terminals of the heaters 32A and 32B in each zone are located at the center of the mounting table 26 (see FIG. 1), and the feeding terminals 36A and 36B made of, for example, Ni are respectively provided at these connecting terminals, for example. It is joined by Ni-Au soldering. These power feeding rods 36A and 36B extend downward, extend through the hollow leg portion 28 to the outside, and are connected to a power supply 37 for supplying electric power.

In addition, although only one feed bar 36A, 36B is described in FIG. 1, respectively, two pieces are actually provided.

The upper end of the ceramic leg portion 28 is hermetically joined to the lower surface of the center portion of the mounting table 26. Moreover, 28 A of attachment flange parts of the lower end part of this leg part 28 are airtightly attached to the bottom part 16A of the recessed part 17 which defines the exhaust space 18. As shown in FIG. In addition, an inert gas such as N ₂ gas is supplied into the leg portion 28.

When the semiconductor wafer to be processed is a 300 mm wafer, the diameter of the mounting table 26 is about 340 mm, and the diameter of the leg 28 is about 40 mm to 50 mm.

In the center part of the rear surface side (lower surface side) of the mounting table 26, the temperature measuring part 38 is provided in correspondence with 34 A of innermost heating zones, here, an inner heating zone, and 34 A of inner heating zones are provided. It is possible to measure the temperature of. As this temperature measuring part 38, a thermocouple can be used, for example, and this thermocouple is attached to the center of the rear surface of the mounting table 26 by fusion. In this case, since the temperature measuring part 38 made of this thermocouple is in the state accommodated in the leg part 28, a thermocouple is not exposed to the various gas supplied in the processing container 4, and corrosion of a thermocouple is prevented. .

The wiring 40 extending from the temperature measuring part 38 extends through the bottom part 16A side to the outside and is connected to a power supply control part 42 made of, for example, a microprocessor (computer). And this power supply control part 42 is able to control each heater 32A, 32B of the said heating zone based on the detection value of the said temperature measuring part 38. As shown in FIG. In this case, the inner side zone heater 32A of the said inner side heating zone 34A is feedback-controlled so that the process temperature of a film-forming process may be maintained. In contrast, the outer zone heater 32B of the outer heating zone 34B is connected to the inner zone heater 32A even if the inner zone heater 32A is controlled in any control mode such as current control, voltage control, and power control. On the basis of the supply power, the power determined by the predetermined safe supply power ratio is set to be supplied, and the control of the open loop is performed.

For example, when the safety supply power ratio at a certain process temperature is 0.8, 0.8 times the power supplied to the inner zone heater 32A is controlled to be supplied to the outer zone heater 32B.

Here, the current control outputs an operation amount corresponding to the difference between the set temperature and the actual temperature in the form of a current, the voltage control outputs the difference as a voltage, and the power control outputs the difference as power.

The safety supply power ratio is determined so that the temperature difference between the heating zones is such that the mounting table 26 is not damaged, and depending on the process temperature, the mounting table 26 is reduced even if the in-plane uniformity of the film thickness is slightly reduced. It is also possible to set the power ratio to prevent breakage. This point is mentioned later.

In addition to controlling the operation of the placement table device 24, the power control unit 42 also has a function of controlling the entire operation of the processing device 2, and the power control unit 42 controls the operation. The storage medium 44 which stores the program to be connected is connected. As the storage medium 44, for example, a flexible disk, a flash memory, or the like can be used.

On the other hand, a plurality of pin holes 46 are formed in the mounting table 26 so as to penetrate in the vertical direction, and lower ends of the pin holes 46 are commonly connected to the connecting ring 48, for example, made of quartz. Of the push-up pins 50 are accommodated in a fluidly fitted state. The connection ring 48 is connected to an upper end of the sunken rod 52 installed to penetrate the bottom of the container and move up and down, and the lower end of the sunken rod 52 is an air cylinder 54. Is connected to. As a result, the push-up pins 50 are projected upward from the upper end of each pin hole 46 at the time of transferring the wafer W. As shown in FIG. In addition, a bellows 56 that can be stretched and interposed is provided at a penetrating portion of the sunken rod 52 to the bottom of the container, and the sunken rod 52 maintains airtightness in the processing container 4. It is possible to get on and off.

Next, a film formation method (including a temperature control method) performed using the processing apparatus 2 configured as described above will be described.

First, if the push-up pin 50 is moved up and down and the unprocessed semiconductor wafer W is placed on the mounting table 26 maintained at the process temperature to seal the inside of the processing container 4, the vacuum exhaust system 22 is closed. By this, the inside of the processing container 4 is maintained at a predetermined process pressure, a predetermined processing gas (film forming gas) is introduced into the processing container 4 from the shower head portion 6 which is a gas supply means, and the wafer is formed by CVD. A predetermined thin film is formed at (W). For example, when forming a TiN film by thermal CVD as an example, NH ₃ gas is supplied to one gas space 8A of the shower head portion 6, and TiCl ₄ + N ₂ gas is supplied to the other gas space 8B. These gases are mixed in the processing space S to form a TiN film.

By the way, in performing this film-forming process, the said power supply control part 42 uses the said power supply part 37 based on the measured value from the temperature measuring part 38 which consists of a thermocouple provided in the center part of the lower surface of the mounting table 26. The amount of operation to the zone heaters 32A and 32B is controlled through this. For example, the supply voltage to the inner side zone heater 32A of the inner side heating zone 34A is feedback-controlled so as to maintain the process temperature of this film-forming process (voltage control). On the other hand, the outer zone heater 32B of the outer heating zone 34B has a power determined by a predetermined safety supply power ratio based on the supply power (not the supply voltage) to the inner zone heater 32A. And control of the open loop is made. As a result, the temperature difference between the inner and outer circumferences of the mounting table 26 can be prevented from becoming excessively large, and the mounting table 26 can be prevented from being damaged.

The temperature distribution of the mounting table 26 at this time is the temperature distribution in which the temperature of the center part of the mounting table 26 is the lowest, and gradually increases in temperature as it approaches the peripheral part (edge part), ie, the temperature distribution state of a center cool. have. The state of this temperature distribution is demonstrated with reference to FIG.

It is a figure which shows typically the relationship of the process gas concentration and temperature distribution in the radial direction of a semiconductor wafer. Generally, the processing gas is supplied to the processing space from the shower head portion 6 provided on the ceiling of the processing container, and is flowed down into the processing space to diffuse substantially evenly toward the periphery of the mounting table 26 so that the processing table is placed. (26) It is to exhaust from below. Therefore, the concentration of the processing gas supplied from the shower head portion 6 to the processing space is high at the wafer center portion and gradually decreases as it goes to the edge portion. As a result, when the wafer temperature is uniform throughout, the reaction in the portion (center portion) having a high gas concentration is promoted, and the film thickness of this portion is thicker than the other portion (edge portion), which is not preferable.

Therefore, as shown in FIG. 3, the reaction at the center portion is suppressed by setting the wafer temperature at the center portion of the wafer to be the lowest, and the temperature distribution state of the center cool at which the temperature gradually increases as it goes to the edge portion. As a result, the in-plane uniformity of the film thickness is set to be higher. Thus, the state which sets temperature of center part lower than the periphery of a wafer is called center cool state. In addition, the opposite temperature relationship is called the center hot state.

In this case, depending on the process temperature, in the case of a wafer having a diameter of 300 mm, the temperature difference Δt of the wafer center portion and the edge portion is, for example, about 5 ° C.

By the way, in the temperature distribution state of the center cool as mentioned above, when the said temperature difference (DELTA) t becomes excessively large, a big stress concentration will be in the junction part of the mounting table 26 which consists of ceramic materials, and the leg part 28 which consists of ceramic materials. It turned out that it was found that the mounting table 26 was broken. According to the research of the present inventors, in the case of the temperature distribution of center cool, the upper limit of the said temperature difference (DELTA) t is about 33 degreeC, and setting the temperature difference (DELTA) t to 33 degrees C or less is required for damage prevention.

As described above, in the temperature control in the conventional mounting table apparatus, the feedback control is performed based on the measured value in the temperature measuring section made of the thermocouple with respect to the inner heating heater, and the process of the temperature of the outer heating heater is performed. The outer current heater is open-looped so as to obtain a current ratio or a voltage ratio having the best in-plane uniformity of the film thickness in correspondence with the temperature, and to maintain the current or voltage corresponding to the current ratio or the voltage ratio based on the inner heater. Was controlling.

However, in such a conventional control method, when a thermal disturbance such as arranging the wafer W at room temperature is applied on the mounting table 26 which is temperature controlled at about 700 ° C., a large temperature difference between the central portion and the edge portion of the mounting table is applied. Occurred, and the placement table 26 was damaged due to this. Thus, it is thought that one of the causes of the temperature difference is that the electrical resistance of the heater made of molybdenum wire fluctuates depending on the temperature.

Therefore, in the present invention, instead of the current ratio and the voltage ratio, the outer zone heater 32B is controlled by the power ratio as described above. In this case, if the power ratio is simply controlled so that the in-plane uniformity of the film thickness is always the best, in some cases, the temperature difference Δt may increase beyond 33 ° C. In this case, the in-plane uniformity of the film thickness Even if it lowers a little, it sets to the electric power ratio which does not cause damage to the mounting table 26.

In the following, a process for obtaining an optimum power ratio, that is, a safety supply power ratio, will be described. First, in the general processing apparatus, the ratio of the supply power to the outer zone heater 32B to the supply power of the inner zone heater 32A, that is, the supply power ratio (outer zone heater supply power / inner zone heater supply power = OUT / IN) And the nonuniformity of the film thickness in the wafer plane are as shown in FIG. 4. In addition, the less the nonuniformity of the film thickness, the better the in-plane uniformity of the film thickness. That is, FIG. 4 shows that the nonuniformity of the film thickness when the supply power ratio is " 1.1 " is the smallest, and the in-plane uniformity of the film thickness is excellent. The optimum power supply ratio seen from the nonuniformity of the film thickness varies depending on the process temperature.

Therefore, first, the supply power ratio (OUT / IN) in which the in-plane uniformity of the film thickness is the best is obtained in advance for various process temperatures, for example, for various process temperatures within the range of about 400 ° C to 900 ° C. . For example, when the process temperature is 400 ° C and 450 ° C, the supply power ratio is "0.65". When the process temperature is 500 ° C and 550 ° C, the supply power ratio is "0.70". Obtain it as follows.

In the actual process, if the supply power to the outer zone heater 32B is controlled at the supply power ratio as described above in accordance with the process temperature, an optimum center cool state is obtained, and the thin film is formed with the best in-plane uniformity of the film thickness. In this case, breakage may occur in the mounting table 26 depending on the conditions.

Thus, in order to prevent occurrence of this breakage, a limit is placed on the power supply ratio. That is, first, the power to the outer zone heater 32B is controlled at various process temperatures (660 ° C. or lower) in advance to actually perform the film forming process, and at that time, the placement table 26 is damaged. Was examined. In addition, feedback control was performed on the inner zone heater 32A to maintain the set process temperature. The result at that time is shown in FIG. In FIG. 5, the horizontal axis represents the number of tested heaters.

As is apparent from FIG. 5, in this mounting table, when the supply power ratio is approximately "1.00", cracks occur in the mounting table (left side in the drawing), and when cracks do not occur (right side in the drawing) It was found to be separated by). Therefore, in the case of the process temperature of 660 degrees C or less, when a supply electric power ratio is set to 1.00 or less, it turns out that damage is not produced to the mounting table 26. FIG.

Therefore, when process temperature is 660 degrees C or less, when supply power ratio which can obtain the in-plane uniformity of the best film thickness is 1.00 or less, let this power supply ratio be a safety supply power ratio. On the other hand, when the supply power ratio which can obtain the in-plane uniformity of the best film thickness exceeds 1.00, let "1.00" be the safe supply power ratio of the process temperature. In other words, in the case where the supply power ratio exceeds "1.00", the mounting table 26 is secured at the expense of the in-plane uniformity of the film thickness.

Similar considerations to those described above were also made for the case where the process temperature was larger than 660 ° C. As a result, in the case of the process temperature higher than 660 degreeC, when the supply power ratio was set to "0.82" or less, it turned out that the damage to the mounting table 26 does not occur. And the safety supply power ratio for every process temperature obtained by the above is memorize | stored in the power supply control part 42 previously. Therefore, if the temperature according to this power supply ratio is controlled, in the temperature distribution state of center cool, the temperature difference (DELTA) t between the inner and outer peripheries of the mounting table 26 can be controlled within 33 degreeC, and this damage can be prevented. have.

The result of the supply power ratio calculated | required in the above is shown in FIG. 6 is a graph showing the range of the allowable power supply ratio depending on the process temperature, and also shows the control range in the case of control by the conventional supply voltage ratio for reference. In this figure, the state of the center cool becomes larger toward the right side, and the center hot state becomes toward the left side. As described above, when the process temperature is 660 ° C or lower, the supply power ratio is allowed in the range of 0.38 to 1.00, and when the process temperature is larger than 660 ° C, the supply power ratio is allowed in the range of 0.38 to 0.82. Moreover, as a result of experiment, in the case of the center hot whose temperature of a center part is higher than a wafer edge part, damage did not occur in the mounting table 26 until the temperature difference became about 70 degreeC.

In addition, in the control range by the conventional supply voltage ratio shown by reference, the placement table crack may generate | occur | produce in the area | region A1 shown to the right, and it was unpreferable.

Next, the conventional voltage ratio control and the power ratio of the present invention were controlled. Changes in the heater temperature and the operation amount at that time will be described with reference to FIGS. 7A and 7B.

FIG. 7A shows a case of conventional voltage ratio control, and FIG. 7B shows a case of power ratio control of the present invention. In each graph, the left vertical axis represents the heater temperature (inner zone heater), and the right vertical axis represents the operation amount. Here, in the case of FIG. 7A, the manipulated variable 100% represents 200 volts, and in the case of FIG. 7B, the manipulated variable 100% represents 4000 watts. The set process temperature at this time is 700 ° C, and the set supply voltage ratio (in the case of FIG. 7A) and the supply power ratio (in the case of FIG. 7B) are "0.95" and "0.82", respectively.

As shown, the change in the operation amount of each heater from the wafer loading and the change in the heater temperature are shown. In the case of the conventional voltage ratio control shown in Fig. 7A, the temperature until the temperature becomes stable after wafer loading. The fluctuation amount H1 is a very large value. Such a large temperature fluctuation amount H1 causes a large temperature difference between the inner and outer circumferences of the mounting table 26, and as a result, the breakage of the mounting table 26 occurs.

On the other hand, in the case of the power ratio control of the present invention shown in FIG. 7B, the temperature fluctuation amount H2 until the temperature is stabilized after the wafer loading is quite small, and is about half as compared with the case of FIG. 7A. have. As a result, it can be seen that the temperature difference generated between the inner and outer circumferences of the mounting table 26 is not so large that it is possible to prevent the mounting table 26 from being damaged, and exhibits good results.

In the above embodiment, the temperature control of the mounting table 26 when the process is actually performed has been described, but in practice, the temperature at which the mounting table 26 does not cause cracks even when the mounting table 26 is raised or lowered. Control is required. In this case, at the time of raising and lowering the mounting table 26, the temperature of the inner heating zone 34A is maintained at a predetermined temperature difference, for example, 33 ° C. or more lower than the temperature of the outer heating zone 34B. . Specifically, the temperature is elevated in a state of center hot or the temperature is elevated in a state where the temperature difference is 33 ° C. or lower even in the state of center cool. Even in the case of center hot, when the temperature difference is, for example, about 70 ° C. or more, since the placing table 26 is damaged as described above, the temperature difference is less than that.

Here, with reference to FIG. 8, an example of the change state of the temperature of a heater and the supply power ratio at the time of the temperature increase of the mounting table 26 is demonstrated. Here again, the safety supply power ratio at the process is set to "0.82".

First, in the idling state, the heater temperature is maintained at 300 ° C, and the supply power ratio at this time is maintained at "0.58". In this case, the control is performed such that the inner circumferential temperature of the mounting table is in a state of center hot higher than the outer circumferential temperature. Then, the heater is heated at a temperature increase rate of, for example, about 5 ° C / min by increasing the power supplied to both heaters while maintaining the above power supply ratio, that is, while maintaining the state of center hot. And when heater temperature reached 700 degreeC which is process temperature (setting temperature), the said supply power ratio will be gradually changed so that it may sequentially approach "0.82" which is a safe supply power ratio. As a result, the temperature distribution of the mounting table is sequentially shifted from the state of the center hot to the state of the center cool.

In this way, if the temperature of the heater is stabilized, the wafer is placed on the mounting table to start the film forming process. In addition, what is necessary is just to control a heater temperature by making the above process reverse, at the time of temperature fall of a heater.

In this way, even when the heater is raised and lowered, the temperature difference between the inner and outer circumferences of the mounting table can be set to a temperature difference at which it does not crack, so that damage to the mounting table can be prevented.

In addition, this invention is not limited to the said embodiment, It can variously change. For example, each numerical example used in the above description is merely an example, and the numerical value also changes depending on the design of the mounting table 26, the resistance heating heater 30, and the like.

In addition, in the said embodiment, although the case of film-forming processing was demonstrated as an example of a process process, it is not limited to this, This invention can be applied to various heat processings, such as an etching process, an oxidation-diffusion process, an annealing process, a modification process, and more. Furthermore, this invention can be applied also to a plasma processing apparatus.

In addition, in the said Example, although the case where two heating zones were installed concentrically was demonstrated as an example, it is not limited to this, The case can also apply this invention also when installing three or more heating zones concentrically. . Also in this case, in the temperature distribution state of the center cool, the safety supply power ratio is set in a temperature range in which the temperature difference between the heating zone around the innermost circumference and the heating zone around the outermost circumference is not broken, for example, within 33 ° C. Of course.

Moreover, it is not limited to a semiconductor wafer as a to-be-processed object, An LCD substrate, a glass substrate, a ceramic substrate, etc. can also be used.

Claims (12)

A mounting table for placing the object to be processed,
A heating mechanism including a plurality of heating heaters provided for each of the plurality of heating zones concentrically partitioned on the mounting table;
A leg portion connected to the center of the mounting table and supporting the mounting table horizontally;
A temperature measuring unit provided in correspondence with the heating zones of the innermost peripheries in the plurality of heating zones;
Feedback control of the temperature of the heating heater of the innermost circumference based on the measured value of the temperature measuring part, and the temperature difference between the heating zones is determined so that the placement table is not damaged. Power supply control part which controls supply power to another heating heater part by safety supply power ratio
Placement device including. The method of claim 1,
The said safety supply power ratio is set so that the temperature of the heating zone of the innermost periphery of the said mounting table may become lowest. The method of claim 2,
The said safety supply electric power ratio is a placement table apparatus which is set to the electric power ratio which the temperature difference between the heating zone of the innermost periphery and the outermost periphery becomes less than 33 degreeC, when the said mounting table corresponds to the to-be-processed object of 300 mm in diameter. . The method of claim 1,
And the power control unit controls the temperature of the heating zone of the innermost periphery to be lower than the temperature of the heating zone of the outermost periphery by a predetermined temperature difference or more at the time of the temperature increase and the temperature decrease of the placement table. The method of claim 1,
When the temperature of the placement table is elevated, the power supply controller increases the temperature of the heating zone of the innermost circumference than the outermost circumference and raises the power supplied to each of the heating heaters to the safety supply power ratio when the set temperature is reached. Placement device to control to sequentially approach. The method of claim 1,
The temperature measuring unit comprises a thermocouple. The method of claim 1,
At least one of the placing table and the leg portion is made of a ceramic material. A processing apparatus for performing a predetermined heat treatment on a target object,
A processing container configured to exhaust the internal atmosphere,
A gas supply mechanism for supplying a gas required in the processing container;
Placement device for placing the workpiece
Including,
The placement table device,
A mounting table for placing the object to be processed,
A heating mechanism including a plurality of heating heaters provided for each of the plurality of heating zones concentrically partitioned on the mounting table;
A leg portion connected to the center of the placement table and supporting the placement table horizontally;
A temperature measuring unit provided in correspondence with the heating zones of the innermost peripheries in the plurality of heating zones;
The feedback control of the temperature of the heating heater part of the innermost circumference based on the measured value of the temperature measuring part, and it is determined that the temperature difference between the heating zones is a range that does not damage the placement table for the heating heater part of the innermost circumference Power supply control part which controls supply power to another heating heater part by safety supply power ratio
Processing apparatus comprising a. The object to be processed is placed on a mounting table provided in a processing container configured to exhaust the internal atmosphere, and a heating mechanism including a plurality of heating heaters provided for each of the plurality of heating zones concentrically partitioned on the mounting table controls the heating mechanism. As a method of controlling the temperature of the workpiece,
Measuring the temperature of the heating zone of the innermost periphery in the plurality of heating zones,
Controlling the heating heater unit around the innermost periphery to be a set temperature based on the measured temperature;
Controlling supply power to other heating heaters at a safety supply power ratio to the heating heater section around the innermost circumference, determined so that the temperature difference between the heating zones is such that the mounting table is not damaged.
Temperature control method comprising a. 10. The method of claim 9,
And a temperature control method of maintaining the temperature of the heating zone at the innermost circumference lower than the temperature of the heating zone at the outermost circumference by a predetermined temperature difference or more at the time of the temperature increase of the placing table. 10. The method of claim 9,
And a temperature control method of maintaining the temperature of the heating zone of the innermost circumference not to be lower than the temperature of the heating zone of the outermost circumference by a predetermined temperature difference or more at the time of lowering of the mounting table. The object to be processed is placed on a mounting table provided in a processing container capable of evacuating an internal atmosphere, and a heating mechanism including a plurality of heating heaters provided for each of the plurality of heating zones concentrically partitioned on the mounting table is controlled. In controlling the temperature of the object to be treated and performing a predetermined treatment on the object,
Measuring the temperature of the heating zone of the innermost periphery in the plurality of heating zones,
Controlling the heating heater unit around the innermost periphery to be a set temperature based on the measured temperature;
Controlling supply power to other heating heaters at a safety supply power ratio to the heating heater section around the innermost circumference, determined so that the temperature difference between the heating zones is such that the mounting table is not damaged.
A storage medium in which a program for controlling a processing device in a computer is stored so as to perform a temperature control method comprising a.

Images