KR100713288B1 - Method of determining set temperature trajectory for heat treatment system - Google Patents

Abstract

The present invention relates to a method for determining a set temperature trajectory in a heat treatment apparatus for performing a first heat treatment and a second heat treatment on a workpiece.

The method includes performing a first heat treatment process on a first test object using a temporary first set temperature trajectory, measuring a result of the first heat treatment process performed on the first test object, and And determining the first set temperature trajectory in the first heat treatment process by modifying the temporary first set temperature trajectory based on the measurement result of the first heat treatment process. In addition, the present invention, the step of performing the second heat treatment process to the second test object to be subjected to the first heat treatment process using the first set temperature trajectory determined by using a temporary second set temperature trajectory Measuring the results of the first heat treatment process and the second heat treatment process performed on the second test target object, and the temporary agent based on the measurement results of the first heat treatment process and the second heat treatment process. And modifying the second set temperature trajectory to determine the second set temperature trajectory in the second heat treatment process.

Description

Method of determining set temperature trajectory in heat treatment apparatus {METHOD OF DETERMINING SET TEMPERATURE TRAJECTORY FOR HEAT TREATMENT SYSTEM}

1A and 1B are configuration diagrams for describing one embodiment of the present invention;

2 is a flowchart showing a procedure for optimizing a set temperature in a reaction tube corresponding to a plurality of heaters, for each of two films formed successively;

3 is a flowchart detailing the step 121 in FIG. 2;

4 is a flowchart detailing the step 122 in FIG.

5A to 5C are control diagrams showing the temperature of the wafer for explaining the optimization operation of the first set temperature for forming the first film;

6A and 6B are control diagrams showing the temperature of the wafer for explaining the optimization operation of the second set temperature for forming the second film;

7A to 7C are control diagrams showing the temperature of the wafer for explaining the optimization operation of the first dynamic set temperature for forming the first film;

8A and 8B are control diagrams showing the temperature of the wafer for explaining the optimization operation of the second dynamic set temperature for forming the second film;

9A to 9C are explanatory diagrams for showing that the film thickness in the wafer is made uniform by a decrease in temperature during film formation;                 

10A to 10C are diagrams showing an example of the distribution of the film thickness on the wafer in the wafer boat;

FIG. 11 is a flowchart showing a procedure for optimizing a set temperature in a reaction tube corresponding to a plurality of heaters with respect to each of two films formed successively, which is different from those shown in FIGS. 2 to 4;

12 is a flowchart detailing the step 221 in FIG. 11,

13 is a flowchart detailing the step 222 in FIG. 11,

FIG. 14 is a flowchart showing a case where the first and second films are continuously formed by the heat treatment apparatus shown in FIG. 1A;

15 is a table showing the components of the gate-oxide-film forming process as an embodiment of the present invention in comparison with the comparative example.

<Description of the symbols for the main parts of the drawings>

 11: reaction tube 12: inner tube

13: wafer boat 14: wafer

15: thermos 16: manifold

17: base plate 18: cover body

19: boat elevator 20: gas supply pipe

21: exhaust pipe 22, 23, 24, 25, 26: heater

27, 28, 29, 30, 31: external thermocouple

32, 33, 34, 35, 36: internal thermocouple                 

37: state estimation 38: control unit

39: optimizer

The present invention relates to a method for determining a set temperature trajectory in a heat treatment apparatus for performing heat treatment such as forming a film on a workpiece. In particular, the present invention relates to a method for determining a set temperature trajectory in a heat treatment apparatus suitable for forming an accurate film.

In the process of manufacturing a semiconductor device or the like, the step of heat-treating the wafer to form a specific film on its surface is indispensable. In such a heat treatment process, a chemical vapor deposition process (CVD process), an oxidation-diffusion process, and the like are performed in a heat treatment apparatus at a relatively high temperature such as about 750 ° C. to about 900 ° C.

In general, a heat treatment apparatus includes a holder called a wafer boat for arranging and holding a plurality of wafers in a shelf shape, a cylindrical reaction tube containing the holder and surrounding the holder, and a circular shape surrounding the side surface of the reaction tube. A gas introduction pipe having a plurality of heaters divided in the axial direction and introducing a reaction gas into the reaction tube, and an exhaust pipe for removing exhaust gas from the reaction tube.

Predetermined power is supplied to the heater, and control is made to maintain the wafer temperature for film formation. Here, in practice, it is impossible to measure the wafer temperature itself during the film forming process. It is common to use the measured temperature at the site of its replacement to control the process temperature.

Such control of the heater output is an essential condition for ensuring precision and performing heat treatment such as film formation on the wafer. Hereinafter, as a representative example of the heat treatment, a film forming step will be described as an example.

In the film forming step, the film thickness and the film quality change when the wafer temperature is slightly different from the setting. For example, in some film-forming processes, the difference of 1 degreeC of temperature becomes the difference of 0.1 nm of formed film thickness. Therefore, in the case where the thickness of a certain film as a whole is about several nm to several tens of nm, control of at least several degrees Celsius is required for several hundred degrees Celsius.

The concentration of the reaction gas is not uniform in the reaction tube because a constant flow is given from the gas introduction side to the exhaust side. Therefore, if the same temperature control is performed at either site of the reaction tube, This is because the film thickness on the wafer is rather different. In addition, it is common for the control of each of the plurality of heaters divided in the array direction of the plurality of wafers to be heat treated to be different, including the set temperature.

In this way, in order to form the same and highly accurate film thickness on the wafer in the reaction tube, the set temperature in the reaction tube corresponding to the plurality of heaters is optimized (modification can be repeated several times to obtain the film thickness within the allowable range). It is necessary to do                         

In order to optimize the set temperature, for example, a film is formed at a set temperature at which a plurality of test wafers are placed in a reaction tube, the film thickness is measured by a measuring instrument, and corresponding to the plurality of heaters due to an error from a desired film thickness. A method of shifting the set temperature in the reaction tube can be used. Do the same again using the test wafer with the shifted set temperature and repeat until the error in the desired film thickness is accommodated within the allowable range. The set temperature converged in this way is the optimized set temperature in the reaction tube corresponding to the plurality of heaters.

By the way, in a semiconductor manufacturing process, it forms by forming different types of film | membrane. In such a case, the optimized set temperature in the reaction tube corresponding to the plurality of heaters may be obtained for each film forming process.

That is, assuming, for example, that the first film is formed and the second film is formed thereon. First, with regard to the first film formation, the optimized set temperature in the reaction tube corresponding to the plurality of heaters is obtained by the above method. Next, using the wafer on which the first film is formed at the optimized set temperature, the optimized set temperature in the reaction tube corresponding to the plurality of heaters is obtained by the above method with respect to the second film formation. The set temperature can be optimized independently for each film formed in this way.

However, in the semiconductor manufacturing process, the first film and the second film may be formed continuously. When continuously forming the first film and the second film, the wafer is loaded in the heat treatment apparatus to grow the first film, and then the second film is formed on the first film without unloading the wafer from the heat treatment apparatus once.                         

In such a case, data of the film formation result cannot be measured with a measuring device only for the wafers on which the first and second films are formed. Therefore, the optimization method of the independent set temperature for each film | membrane mentioned above cannot be used.

In this case, two cases can be considered in the measurement data of the film formation result of the first film and the second film. That is, in one case, for example, when both the first film and the second film are nitride films, the individual film thicknesses cannot be measured separately, and only the film thicknesses of these two films can be measured. In another case, for example, when the first film is an oxide film and the second film is a nitride film, the film thickness can be measured by distinguishing either film.

In the former, the film formation results can be used to optimize the set temperature for film formation in either the first film or the second film. However, in this way, the total film thickness of the first film and the second film can be controlled. However, the film thickness is not managed in the individual films. It is also conceivable to optimize the set temperature by appropriately distributing the film formation results to the temperature settings of the first and second film formations, but in reality, it is unclear whether the distribution is appropriate. Will not be done.

In the latter case, the order of optimization must be appropriately performed. For example, if the set temperature is optimized for the second film following the formation of the first and second films, and then the set temperature is optimized for the first film, the set temperature for the first film is optimized. There is a fear that the result of the optimization of the set temperature regarding the second film will be affected. Accordingly, it is necessary to further optimize the set temperature with respect to the second film. In this case, it is difficult to optimize the effective set temperature.

As mentioned above, although the film-forming process was demonstrated as an example of heat processing, this can speak about the general heat processing performed by such a heat processing apparatus.

SUMMARY OF THE INVENTION The present invention has been made in consideration of the above-described problems. The present invention relates to a heat treatment apparatus for performing heat treatment such as film formation on a workpiece to be optimized for each set temperature condition in a plurality of heat treatment processes continuously in a reaction tube. An object of the present invention is to provide a method for determining a set temperature trajectory.

MEANS TO SOLVE THE PROBLEM In order to solve the said subject, the method of determining the set temperature trace in the heat processing apparatus which continuously performs a 1st heat processing and a 2nd heat processing to the to-be-processed object which concerns on this invention is a temporary 1st heat processing process. Performing on the first test target object using a set temperature trajectory, measuring a result of the first heat treatment process performed on the first test object, the temporary based on a measurement result of the first heat treatment process Determining a first set temperature trajectory in the first heat treatment process by modifying a first set temperature trajectory of the first heat treatment process, wherein the first heat treatment process is performed using the temporary second set temperature trajectory in the second heat treatment process. Performing on the second test object to be performed using the determined first set temperature trajectory, wherein the first heat target is performed to the second test object Measuring the result of the second process and the second heat treatment process, and modifying the temporary second set temperature trajectory based on the measurement result of the first heat treatment process and the second heat treatment process, thereby performing the second heat treatment process. And determining a second set temperature trajectory at.

According to the above feature, the arbitrary second set temperature trajectory is modified based on the measured result of the first heat treatment process and the second heat treatment process. The first set temperature trajectory in the first heat treatment is already corrected before this point, and as a result, the second set temperature trajectory in the second heat treatment process is optimized.

Preferably, the first set temperature trajectory is fixed and the second set temperature trajectory is fixed.

In this case, the difference between the objects to be processed simultaneously by the heat treatment apparatus in the result of the heat treatment process such as the difference in thickness of the film is reduced. The average thickness of the film formed on the workpiece depends on the treatment temperature.

Also, the first set temperature trajectory can be varied, and the second set temperature trajectory can be varied.

In this case, not only the difference between the components of each workpiece in the result of the heat treatment process such as the film thickness difference can be reduced, but also the features simultaneously processed by the heat treatment apparatus in the result of the heat treatment process such as the film thickness difference. The difference between the bodies is also reduced. Appropriate temperature gradients occur between the peripheral and central portions of the workpiece to be treated by varying the set temperature during the heat treatment process by using a ratio of thermal conditions in the workpiece. Therefore, the difference in deposition conditions such as the concentration of the source gas between the peripheral portion and the central portion of the object to be treated can be offset.

Further, preferably, the heat treatment system is divided into a plurality of regions in which the heat treatment apparatus can be heated respectively, and a first set temperature trajectory is determined in the region of the heat treatment apparatus, respectively, and the first set temperature in the region. The trajectories are different from each other, the second set temperature trajectories are respectively determined in the region of the heat treatment apparatus, and the second set temperature trajectories in the region are different from each other.

Therefore, this method is more effective when different heat treatment conditions need to be set in the tier-like arrangement direction of the workpiece to be treated.

Further, preferably, the first heat treatment process is a gate-oxide-film forming process using thermal oxide, and the second heat treatment process is a nitrogenization process for nitrogenizing the gate-oxide-film.

Furthermore, the present invention relates to a method for determining a set temperature trajectory in a heat treatment apparatus that continuously performs a first heat treatment and a second heat treatment on a target object, and the method further includes a temporary first setting of the first heat treatment process. Performing on the first test target object using a temperature trajectory, measuring a result of the first heat treatment process performed on the first test target object, and based on the measurement result of the first heat treatment process Determining a first set temperature trajectory in the first heat treatment process by modifying a first set temperature trajectory, wherein the first heat treatment process uses the temporary second set temperature trajectory, Performing on the second test object to be performed using the determined first set temperature trajectory, the first heat treatment process and the water to the second test object Measuring the result of the second heat treatment process, modifying the temporary second set temperature trajectory based on the measurement results of the first heat treatment process and the second heat treatment process, Determining a second set temperature trajectory, wherein the third heat treatment process is performed using a temporary third set temperature trajectory, the first heat treatment process is performed using the determined first set temperature trajectory, and the second heat treatment process Performing the third test object to be processed using the determined second set temperature trajectory, the first heat treatment process, the second heat treatment process, and the third heat treatment process performed to the third test object. Measuring a result, and based on the measurement result of the first heat treatment process, the second heat treatment process, and the third heat treatment process, And modifying a third set temperature trajectory, thereby determining a third set temperature trajectory in the third heat treatment process.

In this case, based on the result of the first heat treatment step, the set temperature condition in the reaction tube in the first heat treatment step can be optimized, and based on the result of the first and second heat treatment steps using this set temperature condition. In the second heat treatment process, the set temperature condition in the reaction tube can be optimized. Then, based on the results of the first, second and third heat treatment processes using this set temperature condition, the set temperature conditions in the reaction tube in the third heat treatment process can be optimized. Therefore, the set temperature conditions in the first, second and third heat treatment processes can be managed. Set temperature conditions for four or more heat treatment processes can be optimized in a similar fashion.                     

Preferably, the first set temperature trajectory is fixed, the second set temperature trajectory is fixed, and the third set temperature trajectory is fixed.

The first set temperature trajectory is variable, the second set temperature trajectory is variable, and the third set temperature trajectory is variable.

Further, preferably, the heat treatment apparatus is divided into a plurality of regions each of which can be heated, a first set temperature trajectory is respectively determined in the region of the heat treatment apparatus, and the first set temperature trajectory in the region is mutually different. Different, second set temperature trajectories are respectively determined in the region of the heat treatment apparatus, the second set temperature trajectories in the region are different from each other, and third set temperature trajectories are respectively determined in the region of the heat treatment apparatus. The third set temperature trajectories in the region are different from each other.

Furthermore, the present invention relates to a method for determining a set temperature trajectory in a heat treatment apparatus that continuously performs a first heat treatment and a second heat treatment on a target object, and this method is a temporary first setting of a first heat treatment step. Performing on the first test target object using a temperature trajectory, measuring a result of the first heat treatment process performed on the first test target object, and based on the measurement result of the first heat treatment process Determining a first set temperature trajectory in the first heat treatment process by modifying a first set temperature trajectory, wherein the first heat treatment process uses the temporary second set temperature trajectory, Performing on the second test object to be performed using the determined first set temperature trajectory, and the second heat treatment ball performed to the second test object Determining a second set temperature trajectory in the second heat treatment process by modifying the temporary second set temperature trajectory based on a measurement result of the second heat treatment process. .

In this case, the set temperature in the reaction tube related to each result of the continuous heat treatment process can be optimized. In this case, the optimum set temperature is determined in the first heat treatment process, that is, the best heat treatment process, and then the optimum set temperature is determined in the second heat treatment process, that is, the subsequent heat treatment process. Therefore, the adjustment of the optimum set temperature in the first heat treatment process becomes unnecessary, and therefore the optimum set temperature inside the reaction tube can be effectively determined.

The present invention also relates to a method of continuously performing a first heat treatment and a second heat treatment on a workpiece. The method includes performing a first heat treatment process on a first test object using a temporary first set temperature trajectory, measuring a result of the first heat treatment process performed on the first test object, Determining a first set temperature trajectory in the first heat treatment process by modifying the temporary first set temperature trajectory based on a measurement result of the first heat treatment process, and temporarily setting the second heat treatment process to a second temporary setting. Using the temperature trace, performing the first heat treatment process on the second test object to be performed using the determined first set temperature trajectory, the first heat treatment process to be performed on the second test object, and the Measuring the result of the second heat treatment process, and based on the measurement results of the first heat treatment process and the second heat treatment process, the temporary second set temperature bin Determining a second set temperature trajectory in the second heat treatment step by modifying the product, performing the first heat treatment process on the workpiece using the determined first set temperature trajectory, and the second heat treatment And performing a process on the workpiece to which the first heat treatment process is performed using the determined second set temperature trajectory.

The present invention also relates to a method of continuously performing a first heat treatment, a second heat treatment, and a third heat treatment on a workpiece, wherein the method comprises performing a first test on a first heat treatment process using a temporary first set temperature trajectory. Performing on the object to be processed, measuring a result of the first heat treatment process performed on the first test object, and correcting the temporary first set temperature trajectory based on the measurement result of the first heat treatment process Determining a first set temperature trajectory in the first heat treatment process, using the temporary second set temperature trajectory for the second heat treatment process, and using the first set temperature trajectory in which the first heat treatment process is determined. Performing results on the second test object to be performed, and measuring the results of the first and second heat treatment processes performed on the second test object. Determining a second set temperature trajectory in the second heat treatment process by modifying the temporary second set temperature trajectory based on the measurement results of the first heat treatment process and the second heat treatment process. The third heat treatment process is performed using the temporary third set temperature trajectory, the first heat treatment process is performed using the determined first set temperature trajectory, and the second heat treatment process is performed using the determined second set temperature trajectory. Performing a third test object to be performed; measuring a result of the first heat treatment process, the second heat treatment process, and the third heat treatment process performed to the third test object; and the first heat treatment process And the third row by modifying the temporary third set temperature trajectory based on measurement results of the second heat treatment step and the third heat treatment step. Determining a third set temperature trajectory in the treatment process, performing the first heat treatment process on the object to be processed using the determined first set temperature trajectory, and performing the second heat treatment process on the determined second set temperature Performing a process on the object to which the first heat treatment process is performed using a trajectory, and performing the third heat treatment process using the determined third set temperature trajectory, and performing the second heat treatment. And performing a process on the object to be processed.

The present invention also relates to a method of continuously performing a first heat treatment and a second heat treatment on a target object, performing the first heat treatment process on a first test target object using a temporary first set temperature trajectory, Measuring a result of the first heat treatment process performed on the first test object, and correcting the temporary first set temperature trajectory based on the measurement result of the first heat treatment process, thereby performing Determining a first set temperature trajectory of the second test feature, wherein the second heat treatment process is performed using the temporary second set temperature trajectory, and wherein the first heat treatment process is performed using the determined first set temperature trajectory Measuring the result of the second heat treatment step performed on the second body to be processed; Determining a second set temperature trajectory in the second heat treatment process by modifying the temporary second set temperature trajectory, and performing the first heat treatment process using the determined first set temperature trajectory. And performing the second heat treatment process on the workpiece to which the first heat treatment process is performed using the determined second set temperature trajectory.

[Embodiment of the Invention]

EMBODIMENT OF THE INVENTION Hereinafter, embodiment of this invention is described, referring drawings.

1A and 1B are configuration diagrams for describing one embodiment of the present invention. As shown in FIG. 1A, this embodiment is a heat treatment apparatus having a reaction tube 11, a peripheral device coupled to the reaction tube 11, a state estimation 37, a controller 38, and an offline optimizer 39. to be. The reaction tube 11 and its peripheral apparatus are shown in front sectional view, and the state estimation 37, the control part 38, and the optimization part 39 are shown in the block diagram.

The reaction tube 11 is closed at the top. The lower end of the reaction tube 11 is hermetically joined between the lower surface of the base plate 17 and the upper end of the manifold 16. The inner tube 12 has an upper end opening, and a lower end is supported inside the manifold 16.

In the reaction tube 11, a plurality of, for example, 150 wafers 14, i.e., the workpieces are tier-like in the wafer boat 13, which is a holding tool, spaced in the vertical direction at intervals in a horizontal state, respectively. ) Arranged and arranged. This wafer boat 13 is hold | maintained on the cover body 18 through the heat insulating container (insulation body) 15. As shown in FIG. The cover body 18 is mounted on the boat elevator 19 for carrying in and carrying out the wafer boat 13 into the reaction tube 11. When it is in the upper limit position, the lower end opening of the manifold 16, that is, the lower end opening of the processing vessel composed of the reaction tube 11 and the manifold 16 is closed.

Around the reaction tube 11, heaters 22 to 26 made of, for example, resistance heaters are provided in a ring shape, and the heaters 22 to 26 are axially in the axial direction (as shown in the arrangement of the wafers 14). It is divided into These heaters 22 to 26 can be independently controlled by the control unit 38 to generate heat.

The manifold 16 is provided with a gas supply pipe 20 for supplying gas into the inner tube 12. In addition, the exhaust pipe 21 is connected to the manifold 16 so as to exhaust from the gap between the inner tube 12 and the reaction tube 11. Typically, the plurality of gas supply pipes 20 are connected to the manifold 16 to supply a plurality of gases in the inner pipe 12. However, only one gas supply pipe 20 is shown for simplicity. In the middle of the exhaust pipe 21, a pressure adjusting unit (not shown) is provided, whereby the pressure in the reaction tube 11 is adjusted.

On the inner surfaces of the heaters 22 to 26, external thermocouples 27 to 31 are provided, respectively, to detect the temperature of the site. In addition, the inner surface of the inner tube 12 is provided so that the inner thermocouples 32 to 36 correspond to the outer thermocouples 27 to 31, respectively, to detect the temperature of the portion.

The temperature detected by the external thermocouples 27 to 31 and the internal thermocouples 32 to 36 is guided to the state estimation 37. The state estimating 37 also introduces a control amount for controlling the heaters 22 to 26 by the control unit 38. The state estimation 37 estimates the state (in this case, the temperature) of the wafer 14 heat-treated with the reaction tube 11 from these temperatures and control amounts. It is very difficult to make this estimation directly while measuring the temperature directly during the heat treatment of the wafer 14, and the temperature of the wafer 14 is a parameter directly involved in the growth of the film formed thereon. This is because it is originally necessary to control this.

For this estimation, a model for estimating the temperature of the wafer 14 based on the control amount to the heaters 22 to 26, the detection temperature of the external thermocouples 27 to 31, and the detection temperature of the internal thermocouples 32 to 36 is selected. Obtained in advance, the model is kept in the state estimator 37. Accordingly, the state estimator 37 enters the wafer 14 by inputting the control amount to the heaters 22 to 26, the detection temperature of the external thermocouples 27 to 31, and the detection temperature of the internal thermocouples 32 to 36. The temperature can be estimated.

In addition, the estimated temperature of the wafer 14 can be made into the estimation object regarding the some thing mounted in arbitrary positions of the wafer 14 mounted in the wafer boat 13 by the said model setting method. In the following description, the number (position) of the estimation target is set to 5, and the positions are assumed to be the upper, upper, upper, middle, lower, and lower portions of the wafer boat 13, respectively.

In addition, the estimated temperature of the wafer 14 can be made into the object about two or more specific positions in the wafer 14 by the said model setting method. Selecting these two positions is useful when a proper temperature gradient is produced at the outer circumferential portion and the central portion of the wafer 14 by using the conduction velocity of heat transmitted to the target object.                     

The estimated temperature of the wafer 14 is guided to the controller 38. The control part 38 calculates an appropriate control amount compared with the set temperature, and gives the calculated control amount to each heater 22-26 and the state estimation 37. As shown in FIG.

This set temperature uses the thing optimized in normal semiconductor manufacture. As described above, as described above, the modification is performed several times so that a heat treatment within the allowable range, for example, a film having a predetermined film thickness can be obtained. The present invention is characterized by a method for obtaining this optimum set temperature (set temperature trajectory). For this reason, prior to normal semiconductor manufacture, a wafer for testing is placed on the apparatus shown in Fig. 1A to actually operate the film forming process, thereby obtaining the film forming result of the test wafer. The film formation result is input to the offline optimizer 39, as shown in FIG. 1B, whereby the optimizer 39 outputs the correction set temperature. This correction set temperature is applied to the apparatus shown in FIG. 1A and again similarly to obtain a film formation result. In the optimizer 39, a program embedded in a predetermined program can be used.

In addition, the apparatus shown in FIG. 1A actually needs to be controlled in addition to the gas flow rate from the gas supply pipe 20, the pressure in the reaction tube 11, and the like. These portions are not shown because they are not directly involved in the operation as the present invention.

Incidentally, the set temperature, gas flow rate, and pressure in the reaction tube 11 are different depending on the type and film thickness of the film to be formed in the film forming process, which is heat treatment, and the set temperature, gas flow rate, and reaction in each specific film forming process. The processing procedure regarding the pressure in the pipe 11 and the like is called a recipe. In the description of the present invention, the gas flow rate, the pressure in the reaction tube 11, and the like do not directly relate to each other, but the processing procedure regarding the set temperature is related.

The determination method of the set temperature in the apparatus in the embodiment shown in FIG. 1 will be described with reference to FIGS. 2 to 4. 2 to 4 are flowcharts showing a procedure for optimizing a set temperature in a reaction tube corresponding to a plurality of heaters for each of two films formed successively. These two films are laminated and formed continuously. In this example, the thicknesses of the laminated films cannot be measured, respectively, and the sum of the film thicknesses can only be measured. This is the case where another nitride layer is laminated on the nitride layer.

The thickness tolerance of this two-layer film is assumed to be imposed within a predetermined thickness range, for example, within 4 nm ± 0.5% for a specific value, and the thickness of the underlying first film is, for example, within a predetermined thickness range for a specific value. It is assumed to be charged within 1.5 nm ± 1.0%.

When such a specification is imposed, as shown in Fig. 2, first, the set temperature for forming the first film as the lower layer is optimized (step 121), and then the set temperature for forming the second film as the upper layer is optimized ( Step 122).

In order to optimize the set temperature for forming the first film, as shown in FIG. 3, first, a first film is formed on a plurality of wafers (test wafers) in the apparatus shown in FIG. 1A (step 131). The plurality of wafers include the upper, middle upper part, middle part, middle lower part, and lower part (five pieces in total) of the wafer boat 13 described above. Normally, the second film is formed following the formation of the first film (that is, without unloading the wafer from the device once), but here, only the film formation of the first film is stopped and the test wafer is unloaded from the device. Incidentally, the film-setting temperature of the first film here is extremely standard (for example, the same temperature for the five wafers to be controlled).

In the unloaded test wafer, the thickness of the first film is measured using a film thickness meter such as an ellipsometer (step 132). The film formation result is input to the optimizer 39 shown in Fig. 1B (step 133), and the optimizer 39 calculates and outputs the corrected first set temperature (step 134).

For this calculation, a physical model of the film thickness that grows with respect to values of parameters such as temperature is incorporated into the optimizer 39 in advance, and the modified model is considered to be appropriate for the film formation result and the current first set temperature using this. The method of deriving a 1st set temperature can be employ | adopted.

The film is formed again using a separate test wafer by applying the first set temperature modified in the heat treatment apparatus shown in FIG. 1A (step 135). Then, only the first film is formed, the film is stopped and the test wafer is unloaded from the apparatus. In the unloaded test wafer, the thickness of the first film is measured using a film thickness meter such as an ellipsometer (step 136).

This measured thickness is compared to a predetermined thickness range, for example 1.5 nm ± 1.0% (step 137). If the measured thickness is within this predetermined thickness range, the optimization of the first set temperature for forming the first film ends. The modified first set temperature (modified set temperature trajectory) used to form the film is the optimized first set temperature (set temperature trajectory).

If the measured thickness is not accommodated within the predetermined thickness range, the process returns to step 133 and the film forming result (measured thickness) is inputted to the optimizer 39, and the optimizer 39 performs another modified agent. 1 Estimate the set temperature. In this way, finally, an optimum first set temperature (modified first set temperature) for forming a first film having a thickness that is settled within a predetermined thickness range can be obtained.

Thus, only the process of the 1st film | membrane of two films | membrane can be taken out, film-forming and measuring, and the optimal 1st set temperature which can satisfy | fill the permissible range imposed on a 1st film | membrane can be determined.

Next, the second set temperature for forming the second film as the upper film is optimized. For this purpose, as shown in Fig. 4, first, a first film is formed on a plurality of test wafers in the apparatus at a predetermined set temperature as described above, and then a second film is formed (that is, without unloading) (step 141). . The plurality of test wafers includes the upper, middle upper, middle, middle and lower portions of the wafer boat 13 described above. The second film forming process uses standard temperatures for all five test wafers. In this way, when the first and second films are laminated, the test wafer is unloaded from the heat treatment apparatus.

In the unloaded test wafer, the total thickness of the first and second films is measured using a film thickness meter such as an ellipsometer (step 142). In this case, the film thickness measurement cannot be performed separately for the first film and the second film. The data of this film formation result is input to the optimization part 39 shown in FIG. 1B (step 143). In contrast, the optimizer 39 calculates and outputs the corrected second set temperature (step 144).

For this calculation, the physical model of the film thickness that grows with respect to the parameter value including the temperature is incorporated in the optimizer 39 in advance, and accordingly, it is considered appropriate for the data of the film formation result and the present second set temperature. A method of deriving the modified second set temperature can be employed. This is the same as the optimization of the first set temperature.

The modified second set temperature (set temperature trajectory) is applied to the second film formation, and the first and second films are successively formed by the heat treatment apparatus shown in FIG. 1A again using a separate test wafer (step 145). . In this way, when the first and second films are laminated, the test wafer is unloaded from the heat treatment apparatus.

In the test wafer, the thickness of the two-layer film of the first and second films is measured using a film thickness meter such as an ellipsometer (step 146).

This measured thickness is compared to a predetermined thickness range, eg, 4 nm ± 0.5% (step 147). If the measured thickness is within this predetermined thickness range, the optimization of the second set temperature for forming the second film ends. Here, the modified second set temperature (modified set temperature trajectory) used for the second film formation is the optimized second set temperature (set temperature trajectory).

If this measured thickness is not accommodated within the predetermined thickness range, the process returns to step 143 and the film formation result (measured thickness) is input to the optimizer 39 to perform again. In this way, an optimized second set temperature (modified set temperature) for forming a second film finally contained within a predetermined thickness range can be obtained.

Therefore, this embodiment forms a two-layer film having a thickness (heat treatment synthesis result) in a predetermined range around a set value, and a first film having a thickness (first heat treatment result) in a predetermined range around a set value. Optimal first set temperature and optimal second set temperature can be determined. As a result, the film thickness (second heat treatment result) of the second film can also be managed.

In addition, when the optimum first set temperature and the optimum second set temperature are applied to the heat treatment apparatus shown in Fig. 1A, the semiconductor fabrication of forming a film having such specifications (film quality) becomes possible.

Moreover, it is a case where three or more types of films are laminated | stacked continuously, and even if each film thickness cannot be measured in these laminated films, each set temperature can be optimized similarly.

When forming three films, i.e., the first, the second, and the third film, on the wafer, first, the process of forming the first film is performed, so that the first set temperature is optimized. Next, the process of forming the first and second films is continuously performed by applying the optimized first set temperature, so that the second set temperature is optimized. Finally, the process of forming the first, second and third films is continuously performed by applying the optimized first and second set temperatures, and the third set temperature is optimized. The same applies to the optimization of the set temperatures of four or more membranes.

Next, the controlled temperature change of the test wafer in the apparatus shown in FIG. 1A used for the optimization of the first set temperature and the second set temperature described above will be described with reference to FIGS. 5A to 6B.

5A to 5C are control diagrams showing the temperature of the wafer for explaining the optimization determination of the first set temperature for forming the first film. 5A shows a nominal temperature change curve for forming first and second films on a wafer. Referring to FIG. 5A, first, the wafer is heated to 800 ° C., the wafer is maintained at 800 ° C. for several minutes as a first temperature stabilization process, and a first film deposition process is performed to deposit the first film. A first annealing process is performed to anneal the first film. The wafer is maintained at a fixed control temperature at 800 ° C. during the first temperature stabilization process, the first film deposition process, and the first annealing process.

Then, the temperature of the wafer is lowered to 760 ° C, the wafer is kept at 760 ° C in the second temperature stabilization process, the second film deposition process is performed to form the second film, and the second annealing process forms the second film. To anneal. The wafer is maintained at a control temperature of 760 ° C during the second temperature stabilization process, the second film deposition process and the second annealing process. The temperature of the wafer is lowered after finishing the second annealing step, and the wafer is unloaded from the heat treatment apparatus.

When the temperature in the film forming process of the first and second films is controlled according to the nominal temperature control diagram, the optimum first set temperature (nominally 800 ° C.) for forming the first film is determined by the following procedure.

Referring to Fig. 5B showing the temperature raising process, the first temperature stabilizing process, the first film forming process, the first annealing process, and the first temperature lowering process, the first film is a first set temperature (first set temperature trajectory). The film is formed using a nominal temperature. The optimizer 39 calculates the modified first set temperature based on the data of the film forming result, and the other first film is formed by the first film forming process using the modified first set temperature. The first film deposition and the first set temperature correction are repeated until a first film having a thickness that meets the required specifications is formed. 5C shows the optimal first set temperature determined in this way. As shown in FIG. 5C, the optimum first set temperatures of the upper, upper, middle, middle, and lower regions of the wafer boat 13 are 810 ° C, 805 ° C, 802 ° C, 800 ° C, and 798 ° C, respectively. . In FIG. 5C, the difference between the first set temperatures of the upper, middle, middle, middle, and lower regions of the wafer boat is exaggerated for explanation. This exaggerated illustration is the same in the other drawings.

In this manner, only the first film is formed by the first film forming step of the two films, and the optimum first set temperature which can satisfy the specifications imposed on the first film can be determined by measuring the thickness of the formed first film.

6A and 6B are control diagrams showing the temperature of the wafer for explaining the optimization determination of the second set temperature for forming the second film. The optimization of the second set temperature (here constant at nominal 760 ° C.) for forming the second film will be described below with this temperature control diagram.

With reference to FIG. 6A, the second film forming process for forming the second film using the nominal temperature is performed according to the first film forming process using the optimum first set temperature. The optimizer 39 calculates the modified second set temperature based on the data of the film forming result, and the second film is formed by the second film forming process using the modified second set temperature. The second film deposition and the second set temperature correction are repeated up to the second film thickness where the required requirements are accommodated. 6B shows the optimal second set temperature determined in this way. As shown in FIG. 6B, the optimum second set temperatures of the upper, upper, middle, middle, and lower regions of the wafer boat 13 are 755 ° C, 758 ° C, 759 ° C, 760 ° C, and 762 ° C, respectively. .

Therefore, this embodiment forms a two-layer film having a thickness (heat treatment synthesis result) in a predetermined range around a set value, and a first film having a thickness (first heat treatment result) in a predetermined range around a set value. Optimal first set temperature and optimal second set temperature can be determined. As a result, the film thickness (second heat treatment result) of the second film can also be managed.

Other forms of controlled temperature variation of the test wafer that can be used to determine the optimal first set temperature and the optimal second set temperature of the heat treatment apparatus shown in FIG. 1A will be described with reference to FIGS. 7A-8B. .

7A to 7C are control diagrams showing the temperature of the wafer for explaining the optimization determination of the first dynamic set temperature for forming the first film. 7A shows a nominal temperature change for forming first and second films on a wafer (object to be processed). With respect to FIG. 7A, the wafer is heated, the wafer is held at a temperature for a few minutes by the first temperature stabilization process, the first film deposition process forms the first film, and then the first annealing process anneals the first film. do.                     

In the first film forming step, the temperature is slightly lowered. As such, the first set temperature for the first film forming process is not a fixed temperature but a dynamic set temperature that changes in time. Here, the process of determining the optimum first dynamic set temperature is described. The purpose of growing the first film while slightly lowering the first set temperature is to increase the temperature at the center of the wafer and to produce an outer circumferential portion having a lower temperature than this.

This temperature change not only reduces the variation in the thickness of the formed film on each wafer, i.e., intra-wafer, but also the variation in the thickness of the formed film in the wafers, i.e., inter-wafer, is also small. There is a number. This is because by changing the set temperature during the first film formation, an appropriate temperature gradient is generated to the outer periphery and the center of the wafer by using the speed of heat transmitted in the wafer.

For example, at the outer periphery of the wafer and the central portion, it is intended to offset the difference in the deposition conditions such as the concentration of the deposition gas by an appropriate temperature gradient.

For example, when the set temperature does not decrease during the first film forming process, the film thickness formed in the wafer becomes as shown in Fig. 9A, for example. As shown in Fig. 9A, usually, the film thickness formed at the center of the wafer becomes thinner than the outer circumferential portion, which is mainly caused by the difference in the deposition gas concentration. This is because the deposition gas flows from the outer periphery of the wafer to the center portion and is consumed for film formation during this time, and the concentration of the deposition gas gradually decreases as it goes from the outer periphery of the wafer to the center portion. Therefore, the film thickness becomes thinner at the center part rather than the outer periphery of the film, for example, about 1 nm of moisture. In the following description, the characteristic of the heat treatment apparatus for forming the film having the thickness difference shown in Fig. 9A is called the cup characteristic.]

Therefore, the temperature of the wafer is controlled such that the central portion is somewhat higher, for example, several degrees Celsius than the outer circumferential portion, as shown in Fig. 9B. For this purpose, the temperature during the first film forming process is somewhat lowered. Then, heat is conducted to the outer periphery at the center of the warmed wafer, and a temperature gradient is created in which the temperature decreases toward the outer periphery at the center of the wafer. As a result, as shown in Fig. 9C, a uniform film thickness with high uniformity can be obtained in the wafer.

Returning to the description of FIG. 7A, the temperature is then lowered after the first annealing process for the second film formation. Similarly, a 2nd stabilization process, a 2nd film-forming film process, and a 2nd annealing process are performed. In the second film forming step, the second film is grown while the second set temperature is slightly decreased. Here, it is intended to optimize the second dynamic set temperature. After completion of the second annealing process, the temperature is lowered and the wafer is brought into a state in which it can be unloaded from the heat treatment apparatus.

The optimization of the first dynamic set temperature of the first film deposition process in the film formation process of the first and second films having such a nominal temperature control diagram will be described below.

7B is a control diagram showing the temperature of the wafer for explaining the heating (temperature rise) process, the first stabilization process, the first film deposition process, the first annealing process, and the first temperature fall process. The first film is formed using the nominal temperature as the first dynamic set temperature. The optimizer 39 calculates the modified first dynamic set temperature based on the data of the film formation result, and then the other first film is formed using the modified dynamic set temperature. The steps of first film deposition and first dynamic set temperature correction are repeated until a first film of thickness is formed that meets the required specifications. As shown in FIG. 7C, the first dynamic set temperature in the wafer held in the upper region of the wafer boat 13 is controlled in accordance with the temperature control diagram 171 and maintained in the lower region of the wafer boat 13. The first dynamic set temperature at the wafer is controlled in accordance with the temperature control diagram 172. The first dynamic set temperature at the wafer held in the upper, middle, and lower middle regions of the wafer boat 13, which can be determined by the same order, is omitted in FIG. 7C.

As such, the first film meets the specifications of the film quality required for the film thickness variation (difference) in the allowable inter-wafer and the film thickness variation (difference) in the allowable intra-wafer. The film can be determined by forming and measuring only the first step of two films formed continuously.

8A and 8B are control diagrams showing the temperature of the wafer for explaining the optimization operation of the second dynamic set temperature for forming the second film. Optimization of the second dynamic set temperature for forming this second film is determined by the following procedure.

Referring to FIG. 8A, a second film deposition process for forming a second film using a nominal second dynamic set temperature is performed following a first film deposition process using an optimal first dynamic set temperature. The optimizer 39 calculates the modified second dynamic set temperature based on the result of the film forming data, and the second film is formed by the second film forming process using the modified second dynamic set temperature. The steps of the second deposition and the second dynamic temperature correction are repeated until a second film of thickness is formed that meets the required specifications. As shown in FIG. 8B, the second dynamic set temperature at the wafer held in the upper region of the wafer boat 13 is controlled in accordance with the temperature control diagram 181 and maintained in the lower region of the wafer boat 13. The second dynamic set temperature at the wafer is controlled in accordance with the temperature control diagram 182. The second dynamic set temperature in the wafer held in the upper, middle, and lower middle regions of the wafer boat 13, which can be determined by the same order, is omitted in FIG. 8B.

Therefore, a two-layer film having a thickness (composite result of heat treatment) in a predetermined range around the set value is formed, and a first film, i.e., a lower film, having a thickness (first heat treatment result) in a predetermined range around the set value is formed. Optimally suited to the required quality specification to specify the range of acceptable (inter-wafer) thickness variation (difference) and the range of acceptable intra-wafer thickness (difference) The first dynamic set temperature and the optimal second dynamic set temperature can be determined. As a result, the thickness (second heat treatment result) of the second film can also be managed.

In addition, the use of an optimal dynamic set temperature improves the uniformity of the film when a film having a thickness as shown in FIG. 10A is formed on the wafer held in the upper region of the wafer boat 13 (shown in FIG. 1), In the case where the set temperature does not change dynamically, a film having a thickness as shown in FIG. 10B is formed on the wafer held in the middle region of the wafer boat 13, and a film having a thickness as shown in FIG. It is formed on the wafer held in the lower region of the boat 13.

 This membrane produces the membrane distribution described above when the difference between the deposition conditions in the reaction tube is complex. This membrane has the above-described membrane distribution when gas is supplied into the reaction tube through the top of the reaction tube, and the gas is gradually decomposed in the reaction tube for film formation, thereby generating at least one cup characteristic as shown in 9A. Is generated.

In this case, the film thickness becomes thicker at the center portion than the outer peripheral portion of the wafer. This factor is hereinafter referred to as cap characteristic. This additional factor has little effect on the difference in thickness between the periphery and the center of the film formed on the wafer held in the wafer boat bottom region. When this ancillary factor overlaps the original cup characteristics of the heat treatment system shown in FIG. 1 A, this cap characteristic is superior in the upper region of the wafer boat, and the heat treatment apparatus exhibits cap characteristics (FIG. 10A). In the middle region, the cap and cup characteristics cancel each other so that the film has a nearly flat thickness (Fig. 10B). In the lower region of the wafer boat, the cup characteristics were excellent and overlapped so that the heat treatment apparatus exhibited cup characteristics (FIG. 10C).

As can be seen from the distribution of the film thicknesses shown in Figs. 10A to 10C, in order to make these film thicknesses uniform on film formation on the wafer, the wafers held in the upper region of the wafer boat are somewhat heated up dynamically. A set temperature is used, a constant (static) set temperature is used for the wafer held in the middle region of the wafer boat, and a slightly lower dynamic set temperature is used for the wafer held in the lower region of the wafer boat.                     

As described above, a two-layer film having a thickness (complex result of heat treatment) in a predetermined range around the set value is formed, and a first film having a thickness (first heat treatment result) in a predetermined range around the set value, namely Deposits the underlayer and meets the specifications of the required quality specifying the range of acceptable inter-wafer thickness (difference) and the range of acceptable intra-wafer thickness (difference). Appropriate optimal first dynamic set temperature and optimal second dynamic set temperature may be determined. As a result, the thickness (second heat treatment result) of the second film can also be managed.

Next, another method described with reference to FIGS. 2 to 4 as a method for determining the set temperature in the heat treatment apparatus in the embodiment shown in FIG. 1 will be described with reference to FIGS. 11 to 13. 11 to 13 are flowcharts showing a procedure for optimizing a set temperature in a reaction tube corresponding to a plurality of heaters for each of two films formed successively. These two films are formed successively in a two-layer film, and the thicknesses of the two films can be measured respectively. For example, one of the two films is an oxide film and the other is a nitride film formed on the oxide film.

 The first, that is, the film thickness of the lower film needs to be in a predetermined thickness range for a specific value, such as 1.5 nm ± 1.0%, and the second, that is, the film thickness of the upper film is 2, 5 nm ± 1.0 Assume that it needs to be a certain thickness range for a particular value, such as%.

To meet this requirement, the optimal set temperature for depositing the first, i.e., lower film, is determined in step 221, as shown in 11, and the optimal set temperature for depositing the second, ie, upper film, is determined in step ( 222).                     

Referring to FIG. 12, in order to determine the optimum set temperature for forming the first film, first, on the plurality of test wafers, a film forming process of the first and second films is performed in the heat treatment apparatus shown in FIG. 1A in step 231. It is carried out continuously. The plurality of wafers each include five wafers each held in an upper region, an upper middle region, a middle region, a middle lower region, and a lower region of the wafer boat 13. The test wafer is unloaded from the heat treatment apparatus after completion of the first and second film forming steps. The film forming process of the first and second films uses standard set temperatures for five test wafers.

The thickness of the first film formed on each of the unloaded test wafers is measured at step 232 using a film thickness meter such as an ellipsometer. The film formation result data is input to the optimizer 39 shown in Fig. 1B (step 233), and the optimizer 39 calculates and outputs the corrected set temperature (step 234).

For this calculation, a physical model of the film thickness that grows with respect to a parameter value such as temperature is put in advance in the optimizer 39 and used to derive a new set temperature which is considered appropriate from the film formation result and the current set temperature. The technique to do it can be adopted. This is the same as the description in FIG.

Once the correction set temperature is obtained, this is applied again to form a first film and a second film by means of a separate test wafer (step 235). When the film formation ends, the test wafer is unloaded from the apparatus. In the unloaded test wafer, the thickness of the first film is measured using a film thickness meter such as an ellipsometer (step 236).

The measured film thickness is compared with a predetermined film thickness range, such as 1.5 nm ± 1.0% (step 237). If the measured thickness is within this predetermined film thickness, the determination of the optimum first set temperature for forming the first film ends. Therefore, the first set temperature (modified set temperature trajectory) used for film formation is the optimum first set temperature (set temperature trajectory).

If the measured film thickness is not within the predetermined thickness range, the procedure returns to step 233. Then, the result of the film formation (measured thickness) is input to the optimizer 39, and the optimizer 39 calculates another modified set temperature. Therefore, an optimal first set temperature suitable for forming the first film having the film quality that matches the required film quality is finally obtained.

An optimal first set temperature suitable for depositing a first film meeting the required specification can be determined by depositing both the first film and the second film and measuring the thickness of the deposited first film.

Next, an optimum set temperature for forming the second film, which is the upper film, is determined. As shown in Fig. 13, firstly, the first film is deposited on a plurality of test wafers held in the heat treatment apparatus using the optimum first set temperature, as determined above, and the second film forming process is followed by the first film forming process. It is performed to form a second film on the first film (step 241). The plurality of test wafers includes five wafers each held in the upper region, the upper middle region, the middle region, the middle lower region, and the lower region of the wafer boat 13. The second film deposition process uses standard set temperatures for five test wafers. After the end of the film forming process of the first and second films, the test wafer is unloaded from the heat treatment apparatus.                     

The thickness of the second film formed on each of the unloaded test wafers is measured at step 242 using a film thickness meter such as an ellipsometer. The film formation result data is input to the optimizer 39 shown in Fig. 1B (step 243), and the optimizer 39 calculates and outputs the corrected set temperature (step 244).

For this calculation, a physical model of the film thickness that grows with respect to a parameter value such as temperature is put in advance in the optimizer 39 and used to derive a new set temperature which is considered appropriate from the film formation result and the current set temperature. The technique to do it can be adopted. This is the same as the description in FIG.

Once the corrected set temperature is obtained, this is applied again to form a first film and a second film by a heat treatment apparatus shown in Fig. 1A using a separate test wafer (step 245). When the film formation ends, the test wafer is unloaded from the apparatus.

The thickness of the second film formed on each of the unloaded test wafers is measured using a film thickness meter such as an ellipsometer (step 246).

The measured film thickness is compared with a predetermined film thickness range, such as 2.5 nm ± 1.0% (step 247). When the measured thickness is within this predetermined film thickness, determination of the optimum second set temperature for forming the second film is finished. Therefore, the second set temperature (modified set temperature trajectory) used for film formation is the optimum second set temperature (set temperature trajectory).

If the measured film thickness is not within the predetermined thickness range, the procedure returns to step 243. Then, the result of the film formation (measured thickness) is input to the optimizer 39, and the optimizer 39 calculates another modified set temperature. Therefore, an optimum second set temperature suitable for forming a second film having a film quality that matches the required film quality is finally obtained.

Therefore, this embodiment forms a first film having a film thickness (first heat treatment result) within a range of thickness variation in a predetermined wafer around a set value, and a film thickness within a range of thickness variation in a predetermined wafer around a set value. Determination of an optimum first set temperature and an optimal second set temperature suitable for forming a second film having (second heat treatment result) can be achieved.

In this case, an optimum first set temperature for the first film forming step of the first film to be formed is first determined, and then an optimum set temperature for the second film forming step to be formed later is determined. Therefore, the optimum first set temperature for the film forming process of the first film does not need any readjustment, so that the optimum set temperature in the reaction tube corresponding to the output of the plurality of heaters can be effectively determined.

The first and second set temperatures can be said to be dynamic set temperatures which change with time during the corresponding film formation, respectively. The first and second set temperatures may vary during film formation of the film in different modes of change in different regions.

Incidentally, the heat treatment apparatus shown in FIG. 1A can be formed in accordance with the necessary thickness condition using the determined set temperature. As shown in FIG. 14, the heat treatment apparatus shown in FIG. 1A forms the first film using the optimum first set temperature (step 251), and then forms the second film at the optimum second set temperature following film formation of the first film. (Step 252). FIG. 14 is a flowchart showing a case where a film is continuously formed by the heat treatment apparatus shown in FIG. 1A.

An example of the determination of the optimum set temperature already described with reference to FIGS. 5A-6B will be described according to a specific semiconductor manufacturing process. The semiconductor manufacturing process described here is the formation of a gate oxide film.

In general, the formation of the gate-oxide-film refers to a process of forming an oxide film by thermal oxidation on a semiconductor substrate. The gate electrode of the polycrystalline silicon film is formed on the oxide film (insulating film). For example, polycrystalline silicon is implanted with B (boron), for example, to increase conductivity as an electrode. In recent years, as the integration and miniaturization of semiconductor devices, the thickness of the gate-oxide-film becomes gradually thinner. Therefore, in the heat treatment in the subsequent process, boron (B) injected into the gate electrode layer in the formed gate-oxide-film passes through the diffusion or the semiconductor substrate. If this phenomenon occurs, the characteristics required as a device cannot be maintained.

In order to prevent such B from passing out, it is known that a method of modifying the formed oxide film to form an oxynitride film is effective. Here, the process of continuously heat-processing including such a deformation | transformation (modification) is taken as an example.

The first heat treatment step is a wet thermal oxidation step by steam, and the second heat treatment step is a deformation (modification) (oxynitride film step) of the thermal oxide film carried out under NO atmosphere. Therefore, the object of optimization is the set temperature in each area | region of the wafer boat in a thermal oxidation process, and the set temperature in each area | region of the wafer boat in a reforming process. In addition, the wafer boat is divided into four areas.

First, as a comparative example, the case where the thermal oxide film forming step and the modifying step are performed continuously and the target value of the formed film thickness is set to 1.5 nm will be described. The processing conditions of the process excluding temperature, including gas pressure, gas flow rate, processing time, and the like, are fixed. Appropriate set temperatures for the four regions of the top, middle, bottom, bottom, and bottom of the wafer boat are determined by repeating the measurement of the film thickness formed in the process sequence and the correction of the set temperature.

The set temperatures determined in the four regions are 855 ° C, 855 ° C, 840 ° C and 830 ° C, respectively. The average thickness of the gate-oxide-film formed on the wafer held on the wafer boat using this set temperature is 1.559 nm, and the range of film thickness variation in the wafer is ± 0.65%. The nitrogen concentration in the film is 0.91 to 1.26% [atoms%] per atom (0.91% is the wafer on the wafer boat and 1.26% is the wafer on the wafer boat). In addition, this measurement measures the peak concentration in a film | membrane using secondary ion-mass spectrography (SIMS).

As described above, in the comparative example, the uniformity of the film thickness can be obtained with respect to the wafers in the wafer boat in the process of continuously forming the thermal oxide film forming process and the modifying process, but the nitrogen concentration in the film has a large variation (about ± 16). %), A homogeneous oxynitride film cannot be formed for each wafer.

Next, the result of applying the optimization described using Figs. 5A to 6B will be described. First, the thermal oxidation process is optimized. The target value of the formed film thickness by the thermal oxidation process is 1.65 nm, including the gas pressure, the gas flow rate, the processing time, and the like, and the process conditions except for the temperature are fixed, and the formed film thickness is measured, as described above. By optimizing, appropriate set temperatures are obtained for the four regions of the top, middle, bottom, and bottom of the wafer boat.

The determined set temperatures in the four regions are 805 ° C, 801 ° C, 799 ° C, and 796 ° C, respectively. The average film thickness of the thermal oxide film formed on the wafer held in the wafer boat was 1.667 nm, and the range of the film thickness variation in the wafer was ± 0.47%. In the processing conditions other than the temperature, the flow rate of H ₂ was 0.4 [slm], the flow rate of O ₂ was 0.4 [slm], the flow rate of N ₂ was 30 [slm], the oxidation time was 40 seconds, and the processing pressure was atmospheric pressure. .

Using a predetermined set temperature, the thermal oxide treatment is successively continued to an oxide film modifying process, which includes gas pressure, gas flow rate, processing time, and the like, and the processing conditions of this deformation process except temperature are fixed. . The thickness of the deformed film is measured, and the appropriate set temperature in four areas of the waferboat, namely the top, middle top, bottom and bottom areas, is determined by the procedure already described. The preferred thickness of the modified film is 1.8 nm in the oxide film modification process, and this value is determined on the assumption that the oxide film can be sufficiently effectively deformed with respect to an oxide film having a thickness of 1.65 nm. In the oxide film deformation process, nitrogen contained in the NO gas used for the deformation (modification) diffuses into the oxide film, and oxygen contained in the NO gas increases the thickness of the oxide film. In addition, the processing conditions other than temperature were made into 1 [slm] of NO flow volume, 3 minutes of processing time, and 1 [kPa] of pressure. The set temperatures in the four wafer boat regions used in the oxide film deformation (modification) process, namely, the upper, middle, middle, and lower regions, are 848 ° C, 850 ° C, 851 ° C, and 852 ° C, respectively. The average film thickness of the thermal oxide film formed on the wafer held in the wafer boat is 1.762 nm, and the range of film thickness variation in the wafer is ± 0.64%. The nitrogen concentration of the modified oxide film is in the range of 1.05 to 1.15 [atoms%] per atom (1.05% is the number of atoms in the film formed on the wafer held on top of the wafer boat, and 1.15% is maintained on the bottom of the wafer boat). Number of atoms in the film formed on the wafer). The peak nitrogen concentration of this membrane was measured using SIMS.

This embodiment can perform the thermal oxide film formation process and the deformation (modification) process continuously, and form a uniform film thickness on the wafer held in the wafer boat. The scattering range of the nitrogen content of the membrane is about ± 4.5% narrower than the scattering range of the nitrogen content of the membrane formed by the comparative example. That is, a homogeneous oxynitride film can be formed on the wafer.

This example uses the measured thickness of the strained film as a result of the oxide film strain (modification) process. The thickness of this modified film depends on both the thermal oxide film formation process (first process) and the oxide film modification (modification) process (second process), and only the result of the second process is not measured at the time of optimization of the second process. . That is, the thickness of the deformed film resulting from both the first process and the second process is measured upon optimization of the second process. As a result, the second process can also be properly managed, which is a feature of the present invention. Fig. 15 shows the above examples in comparison with the comparative examples. FIG. 15 is a table comparing elements of a gate-oxide-film deposition process as an embodiment of the present invention with those of a gate-oxide film deposition as a comparative example. FIG.

As described above, according to the present invention, firstly, only the first heat treatment step is selected from among the first and second heat treatment steps that are successively performed, and the heat treatment result of the first to-be-processed object is measured. 1 The heat treatment result is optimized for the set temperature in the reaction tube, and then the optimized set temperature is applied, and then the first and second heat treatments are continuously performed, and the first and second heat treatments By measuring the heat treatment result of the sum, the set temperature in the reaction tube is optimized for the second heat treatment, so that the set temperature in the reaction tube can be optimized for each result of the successive heat treatments.

In addition, first, the first and second heat treatments are performed continuously, and the first heat treatment result of the first and second heat treatment targets is measured to optimize the set temperature in the reaction tube with respect to the first heat treatment. Next, by applying the optimized set temperature, the first and second heat treatments are performed successively, and the second heat treatment result of the object to be treated with the first and second heat treatments is measured, whereby the second heat treatment is performed in the reaction tube. Since the set temperature is optimized, it is possible to optimize the set temperature in the reaction tube for each of the successive heat treatments. In this case, since the optimization of the set temperature is performed first with respect to the first heat treatment, which is performed first, and the optimization of the set temperature is performed with respect to the second heat treatment, which is later performed, the first heat treatment is set again. There is no work to optimize the temperature, and the set temperature in the reaction tube is efficiently optimized.

Claims (20)

In the method of determining the set temperature trajectory in the heat processing apparatus which performs a 1st heat processing process and a 2nd heat processing process continuously to a to-be-processed object, Performing the first heat treatment process on a first test target object using a temporary first set temperature trajectory, Measuring a result of the first heat treatment process performed on the first test object, Determining a first set temperature trajectory in the first heat treatment process by modifying the temporary first set temperature trajectory based on a measurement result of the first heat treatment process, Performing the second heat treatment process on a second test target object subjected to the first heat treatment process using the determined first set temperature trajectory using a temporary second set temperature trajectory, Measuring a total of heat treatment results by the first heat treatment process and the second heat treatment process performed on the second test object, and Determining a second set temperature trajectory in the second heat treatment process by modifying the temporary second set temperature trajectory based on the measured sum of the heat treatment results by the first heat treatment process and the second heat treatment process. Method for determining the set temperature trajectory in the heat treatment apparatus, comprising a. The method of claim 1, wherein the first set temperature trajectory is fixed, and the second set temperature trajectory is fixed. The method of claim 1, wherein the first set temperature trajectory is variable and the second set temperature trajectory is variable. The heat treatment apparatus according to claim 1, wherein the heat treatment apparatus is divided into a plurality of regions each of which can be heated, First set temperature trajectories are respectively determined in the region of the heat treatment apparatus, The first set temperature trajectories in the region are different from each other, Second set temperature trajectories are respectively determined in the region of the heat treatment apparatus; And the second set temperature trajectory in the region is different from each other. The method of claim 1, wherein the first heat treatment process is a gate-oxide-film forming process using thermal oxide, And the second heat treatment step is a nitrogenation step for nitrifying the gate-oxide-film. In the method of determining the set temperature trajectory in the heat processing apparatus which performs a 1st heat treatment process, a 2nd heat treatment process, and a 3rd heat treatment process continuously to a to-be-processed object, Performing the first heat treatment process on a first test target object using a temporary first set temperature trajectory, Measuring a result of the first heat treatment process performed on the first test object, Determining a first set temperature trajectory in the first heat treatment process by modifying the temporary first set temperature trajectory based on a measurement result of the first heat treatment process, Performing the second heat treatment process on a second test target object subjected to the first heat treatment process using the determined first set temperature trajectory using a temporary second set temperature trajectory, Measuring a total of heat treatment results by the first heat treatment process and the second heat treatment process performed on the second test object, Determining a second set temperature trajectory in the second heat treatment process by modifying the temporary second set temperature trajectory based on the measured sum of the heat treatment results by the first heat treatment process and the second heat treatment process. , The third heat treatment process is performed using a temporary third set temperature trajectory, the first heat treatment process is performed using the determined first set temperature trajectory, and the second heat treatment process is performed to determine the determined second set temperature trajectory. Performing on the third test subject to be carried out using, Measuring a total of heat treatment results by the first heat treatment process, the second heat treatment process, and the third heat treatment process performed on the third test object, and The third setting in the third heat treatment step by modifying the temporary third set temperature trajectory based on the measured sum of the heat treatment results by the first heat treatment step, the second heat treatment step and the third heat treatment step. Determining Temperature Trajectory Method for determining the set temperature trajectory in the heat treatment apparatus comprising a. The method of claim 6, wherein the first set temperature trajectory is fixed, the second set temperature trajectory is fixed, and the third set temperature trajectory is fixed. Way. The method of claim 6, wherein the first set temperature trajectory is variable, the second set temperature trajectory is variable, and the third set temperature trajectory is variable. Way. The heat treatment apparatus of claim 6, wherein the heat treatment apparatus is divided into a plurality of regions each of which can be heated, First set temperature trajectories are respectively determined in the region of the heat treatment apparatus, The first set temperature trajectories in the region are different from each other, Second set temperature trajectories are respectively determined in the region of the heat treatment apparatus; The second set temperature trajectories in the region are different from each other, Third set temperature trajectories are respectively determined in the region of the heat treatment apparatus; And the third set temperature trajectory in the region is different from each other. In the method of determining the set temperature trajectory in the heat processing apparatus which performs a 1st heat processing process and a 2nd heat processing process continuously to a to-be-processed object, Performing the first heat treatment process on a first test target object using a temporary first set temperature trajectory, Measuring a result of the first heat treatment process performed on the first test object, Determining a first set temperature trajectory in the first heat treatment process by modifying the temporary first set temperature trajectory based on a measurement result of the first heat treatment process, Performing the second heat treatment process on a second test target object subjected to the first heat treatment process using the determined first set temperature trajectory using a temporary second set temperature trajectory, Measuring a result of the second heat treatment process performed on the second test object, and In the heat treatment apparatus comprising the step of determining the second set temperature trajectory in the second heat treatment process by modifying the temporary second set temperature trajectory based on the measurement result of the second heat treatment process. How to determine the set temperature trajectory of In the method of continuously performing the first heat treatment and the second heat treatment to the target object, Performing a first heat treatment process on the first test target object using a temporary first set temperature trajectory, Measuring a result of the first heat treatment process performed on the first test object, Determining a first set temperature trajectory in the first heat treatment process by modifying the temporary first set temperature trajectory based on a measurement result of the first heat treatment process, Performing the second heat treatment process on a second test target object subjected to the first heat treatment process using the determined first set temperature trajectory using a temporary second set temperature trajectory, Measuring a total of heat treatment results by the first heat treatment process and the second heat treatment process performed on the second test object, Determining a second set temperature trajectory in the second heat treatment process by modifying the temporary second set temperature trajectory based on the measured sum of the heat treatment results by the first heat treatment process and the second heat treatment process. , Performing the first heat treatment process on the object to be processed using the determined first set temperature trajectory, and Performing the second heat treatment process on the workpiece to which the first heat treatment process is performed using the determined second set temperature trajectory; Method for continuously performing the first heat treatment and the second heat treatment to the object to be treated, comprising a. 12. The method of claim 11, wherein the first set temperature trajectory is fixed, and the second set temperature trajectory is fixed. 12. The method of claim 11, wherein the first set temperature trajectory is variable and the second set temperature trajectory is variable. The apparatus of claim 11, wherein the heat treatment apparatus is divided into a plurality of regions each of which can be heated, First set temperature trajectories are respectively determined in the region of the heat treatment apparatus, The first set temperature trajectories in the region are different from each other, Second set temperature trajectories are respectively determined in the region of the heat treatment apparatus; And the second predetermined temperature trajectory in the region is different from each other. 12. The method of claim 11, wherein the first heat treatment process is a gate-oxide-film formation process using thermal oxide, And the second heat treatment process is a nitrogenization process for nitrifying the gate-oxide-film. In the method of continuously performing the first heat treatment step, the second heat treatment step and the third heat treatment step to the object to be treated, Performing a first heat treatment process on the first test target object using a temporary first set temperature trajectory, Measuring a result of the first heat treatment process performed on the first test object, Determining a first set temperature trajectory in the first heat treatment process by modifying the temporary first set temperature trajectory based on a measurement result of the first heat treatment process, Performing the second heat treatment process on a second test target object subjected to the first heat treatment process using the determined first set temperature trajectory using a temporary second set temperature trajectory, Measuring a total of heat treatment results by the first heat treatment process and the second heat treatment process performed on the second test object, Determining a second set temperature trajectory in the second heat treatment process by modifying the temporary second set temperature trajectory based on the measured sum of the heat treatment results by the first heat treatment process and the second heat treatment process. , The third heat treatment process is performed using the temporary third set temperature trajectory, the first heat treatment process is performed using the determined first set temperature trajectory, and the second heat treatment process uses the determined second set temperature trajectory. Performing on the third test object to be performed by Measuring a total of heat treatment results by the first heat treatment process, the second heat treatment process, and the third heat treatment process performed on the third test object, The third setting in the third heat treatment step by modifying the temporary third set temperature trajectory based on the measured sum of the heat treatment results by the first heat treatment step, the second heat treatment step and the third heat treatment step. Determining a temperature trajectory, Performing the first heat treatment process on the object to be processed using the determined first predetermined temperature trajectory, Performing the second heat treatment process on the workpiece to which the first heat treatment process is performed using the determined second set temperature trajectory, and Performing the third heat treatment process on the to-be-processed object on which the first heat treatment process is performed and the second heat treatment process is performed using the determined third set temperature trajectory. Method for continuously performing the first heat treatment, the second heat treatment and the third heat treatment to the object to be treated, characterized in that it comprises a. 17. The method of claim 16, wherein the first set temperature trajectory is fixed, the second set temperature trajectory is fixed, and the third set temperature trajectory is fixed. A method of continuously performing a third heat treatment. The method of claim 16, wherein the first set temperature trajectory is variable, the second set temperature trajectory is variable, and the third set temperature trajectory is variable. A method of continuously performing a third heat treatment. 17. The apparatus of claim 16, wherein the heat treatment apparatus is divided into a plurality of regions each of which can be heated, First set temperature trajectories are respectively determined in the region of the heat treatment apparatus, The first set temperature trajectories in the region are different from each other, Second set temperature trajectories are respectively determined in the region of the heat treatment apparatus; The second set temperature trajectories in the region are different from each other, Third set temperature trajectories are respectively determined in the region of the heat treatment apparatus; And the third set temperature trajectory in the region is different from each other, wherein the first heat treatment, the second heat treatment, and the third heat treatment are successively performed. In the method of continuously performing the first heat treatment step and the second heat treatment step to the object to be treated, Performing the first heat treatment process on a first test target object using a temporary first set temperature trajectory, Measuring a result of the first heat treatment process performed on the first test object, Determining a first set temperature trajectory in the first heat treatment process by modifying the temporary first set temperature trajectory based on a measurement result of the first heat treatment process, Performing the second heat treatment process on a second test target object subjected to the first heat treatment process using the determined first set temperature trajectory using a temporary second set temperature trajectory, Measuring a result of the second heat treatment process performed on the second test object, Determining a second set temperature trajectory in the second heat treatment process by modifying the temporary second set temperature trajectory based on the measurement result of the second heat treatment process, Performing the first heat treatment process on the object to be processed using the determined first set temperature trajectory, and Performing the second heat treatment process on the workpiece to which the first heat treatment process is performed using the determined second set temperature trajectory; Method for continuously performing the first heat treatment and the second heat treatment to the object to be treated, comprising a.

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