JP2005333032A - Forming method of temperature conversion function of processed materials for monitor, calculating method of temperature distribution, and sheet-fed type heat treatment equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide the forming method of a temperature conversion function by which a heat treatment temperature at which a processed material is exposed in a heat treatment process after heat treatment, and temperature distribution is obtained with higher accuracy. <P>SOLUTION: In the forming method of the temperature conversion function to obtain the temperature at which the processed material for a monitor is exposed, from a sheet resistance value before and after the heat treatment of the processed material 5M for the monitor with a metal-containing film formed on its surface, the forming method includes a process to prepare a plurality of sheets of the processed material for the monitor, a process to measure the sheet resistance of the metal-containing film before the treatment, a process to apply the heat treatment to a plurality of the processed materials for the monitor, a process to measure the sheet resistance of the metal-containing film of the processed materials for the monitor after the heat treatment, a calculating process to obtain a finite difference value of the sheet resistance value before and after the heat treatment, a process to obtain a standard finite difference value compensating a quantity of the sheet resistance value in which the sheet resistance value before the heat treatment makes an impact on the sheet resistance value after the heat treatment for the finite difference value, a calculating process to obtain the compensated finite difference value at each heat treatment temperature averaging the standard finite difference value, and a process to obtain the temperature conversion function which is correlation between the temperature in the heat treatment process and the compensated finite difference value, based on the compensated finite difference value. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a temperature conversion function forming method, a temperature distribution calculating method, and a single wafer heat treatment apparatus for obtaining a temperature distribution during heat treatment of an object to be processed such as a semiconductor wafer after the heat treatment.

In general, in the manufacturing process of a semiconductor integrated circuit, various film formations such as W, WSi, Ti, TiN, TiSi, SiO _2, etc. are used to form wiring patterns, hole holes, and interlayer insulating films on the surface of a semiconductor wafer. The film-forming heat treatment is repeated. In addition to the film formation heat treatment, various heat treatments such as etching treatment, oxidation diffusion treatment, and ashing treatment are also performed.
In this case, in order to improve the yield and the like, it is necessary to perform various heat treatments uniformly over the wafer surface. For this purpose, the process pressure, the flow rate of the process gas, the process temperature, etc. are accurately controlled. It must be managed and controlled, especially the management of process temperature. That is, if a temperature difference occurs in the wafer surface during the process, the uniformity of the heat treatment is also lowered. Therefore, it is necessary to maintain the in-plane uniformity of the wafer temperature during the heat treatment process.

  In this case, it is very difficult to measure the temperature of the wafer itself during the heat treatment, and even if the temperature of the mounting table on which the wafer is mounted and the heater embedded in the wafer are detected by a thermocouple, Generally, a temperature difference of several tens of degrees centigrade occurs between the temperature and the temperature of the wafer itself, and it is quite difficult to accurately measure the temperature of the wafer itself. For example, even if the heater temperature is about 680 ° C., the actual temperature of the wafer is, for example, about 600 ° C., which is about 80 ° C. lower than this, and the measured temperature value does not accurately reflect the wafer temperature.

  In addition, the following method using a thermocouple is also known as a method for ensuring the uniformity of the in-plane temperature of the wafer. That is, in order to accurately know the temperature of the wafer itself at the time of heat treatment, a plurality of, for example, about five thermocouples are provided on the surface of the monitor wafer substantially evenly in the surface, and these are introduced into the processing container as a target. A reference value such as the amount of electric power input to the heater and the temperature detection value of the embedded thermocouple, which is a temperature condition (uniform condition of in-plane temperature), is obtained. When the product wafer is actually heat-treated, the temperature uniformity within the wafer surface is controlled by maintaining the input power amount, the temperature detection value of the embedded thermocouple, etc., obtained using the monitor wafer. To ensure.

  In this case, when the inside of the heat treatment apparatus is maintained, the inside of the processing container is cleaned, or when the processing recipe is changed, etc., using the monitor wafer with a plurality of thermocouples as described above, the target surface can be maintained. It is necessary to verify whether the temperature uniformity is maintained at a high level. At this time, it is necessary to install a monitor wafer with a thermocouple on the mounting table, or to remove it after measurement. Each time, it is necessary not only to raise and lower the pressure in the processing container to open the atmosphere, but also to lower the monitor wafer to a room temperature that can be handled by humans. As a result, the measurement takes a lot of time, for example, two days. In some cases, it was necessary to reduce productivity.

Further, since thermocouples are used for temperature measurement, the number of wafers attached to the wafer surface cannot be increased so much, and there is an inconvenience that the detailed temperature distribution in the wafer surface cannot be known.
Therefore, using the phenomenon that the sheet resistance value of the surface changes according to the heat treatment temperature of the semiconductor wafer, the technology to know the temperature distribution of the wafer during the heat treatment by measuring the sheet resistance value after the heat treatment Has also been proposed (Patent Documents 1, 2, and 3).
For example, Patent Literature 1 discloses a technique for obtaining a heat treatment temperature within a range of, for example, about 200 to 500 ° C. by obtaining a graph showing a relationship between a change in sheet resistance value of a semiconductor wafer and a heat treatment temperature. Patent Document 2 discloses a technique for estimating a heat treatment temperature of a wafer within a range of, for example, about 400 to 500 ° C. from a correlation between a sheet resistance value and a heat treatment temperature. Patent Document 3 discloses a technique in which the heat treatment temperature is obtained within a range of about 530 to 720 ° C., for example, from the correlation between the sheet resistance value of the wafer into which impurities are ion-implanted and the heat treatment temperature.

JP-A-8-22963 JP-A-9-292285 JP 2000-208524 A

  By the way, each technique in the above-mentioned patent documents 1 to 3 obtains the temperature or temperature distribution during the heat treatment by measuring the sheet resistance after the heat treatment, and according to this, it is somewhat high. The temperature or temperature distribution can be obtained with accuracy. However, the sheet resistance value after the above heat treatment actually changes not only depending on the heat treatment temperature, but also slightly depends on the sheet resistance value of that part before the heat treatment, so the obtained temperature Alternatively, there is a problem that the temperature distribution is slightly different from the actual temperature or temperature distribution during the heat treatment.

In particular, recently, a metal film such as a titanium film or a tungsten film or a metal nitride film such as a TiN film may be subjected to a heat treatment such as annealing at a low temperature of about 200 to 500 degrees, but at such a low temperature, In the technique (Patent Document 3) in which the heat treatment temperature is obtained from the sheet resistance value of the wafer into which impurities are ion-implanted, since the implanted impurities are difficult to activate, the change in the sheet resistance value itself is small and the heat treatment temperature is obtained. There was a problem that it became more difficult.
The present invention has been devised to pay attention to the above problems and to effectively solve them. An object of the present invention is to provide a temperature conversion function forming method, a temperature distribution calculating method, and a temperature distribution function capable of accurately obtaining the heat treatment temperature and temperature distribution exposed in the heat treatment step after heat treatment even in heat treatment in a relatively low temperature region. The object is to provide a single wafer heat treatment apparatus.

  As a result of intensive studies on the relationship between the heat treatment temperature and the sheet resistance value, the present inventor has found that the sheet resistance value before the heat treatment (hereinafter also referred to as “initial sheet resistance value”) affects the increase in the sheet resistance value after the heat treatment. Therefore, the present invention has been achieved by obtaining the knowledge that, by removing the amount of sheet resistance value that affects this, an accurate heat treatment temperature or a temperature distribution thereof can be obtained.

  The invention according to claim 1 is the formation of a temperature conversion function for obtaining the exposed temperature of the monitor object from the sheet resistance value before and after the heat treatment of the monitor object having a metal-containing film formed on the surface. In the method, a step of preparing a plurality of monitoring objects having a metal-containing film formed on a surface thereof, and a sheet resistance is measured at one or a plurality of locations of the metal-containing film with respect to each of the monitoring objects. A pre-treatment sheet resistance measurement step, a heat treatment step in which the plurality of monitoring objects are subjected to heat treatment at different temperatures, and the pre-treatment sheet resistance with respect to the metal-containing film of the monitoring object after the heat treatment A post-treatment sheet resistance measurement step for measuring the sheet resistance at the same location as the location where the sheet resistance was measured in the measurement step, a sheet resistance value obtained in the pre-treatment sheet resistance measurement step, and the post-treatment sheet A difference value calculation step for obtaining a difference value from the sheet resistance value obtained in the resistance measurement step, and a sheet resistance value amount that the sheet resistance value before the heat treatment affects the sheet resistance value after the heat treatment with respect to the difference value. A step of obtaining a standard difference value by compensating, a correction difference value calculating step of obtaining a correction difference value at each of the heat treatment temperatures by averaging the standard difference value, and the obtained one or more correction difference values And a step of obtaining a temperature conversion function that is a correlation between the temperature in the heat treatment step and the correction difference value based on the temperature conversion function.

As described above, since the sheet resistance value that affects the sheet resistance value after the heat treatment is removed from the sheet resistance value before the heat treatment, it is possible to obtain a highly accurate and appropriate heat treatment temperature and its temperature distribution. In particular, for example, the heat treatment temperature in a low temperature range of about 200 to 500 ° C. and the accuracy of temperature distribution can be improved.
In this case, for example, as defined in claim 2, the object to be monitored is configured by forming a metal-containing film on a silicon substrate via an insulating layer.
Further, for example, as defined in claim 3, the metal-containing film is made of a metal film or a metal nitride film.
For example, as defined in claim 4, the predetermined temperature of the heat treatment is in a range of 200 to 500 ° C.

According to a fifth aspect of the present invention, there is provided a temperature distribution for obtaining a temperature distribution of the monitor object exposed from a sheet resistance value before and after the heat treatment of the monitor object having a metal-containing film formed on the surface. In the calculation method, a step of preparing a monitoring target object having a metal-containing film formed on a surface thereof, and a process before measuring sheet resistance at one or a plurality of locations of the metal-containing film with respect to the monitoring target object A sheet resistance measurement step, a heat treatment step in which the monitor object is subjected to heat treatment by exposing it to a predetermined temperature, and a sheet resistance measurement step before the treatment with respect to the metal-containing film of the monitor object after heat treatment The sheet resistance measurement step after the process of measuring the sheet resistance at the same location as the location where the resistance was measured, the sheet resistance value obtained in the pre-treatment sheet resistance measurement step, and the post-treatment sheet resistance measurement step A difference value calculation step of calculating a difference value between the sheet resistance value,
In the process according to claim 1, the sheet resistance value before heat treatment compensates for the amount of sheet resistance value that affects the sheet resistance value after heat treatment to obtain a standard difference value, and the obtained standard difference value and the invention according to claim 1 And a step of calculating a temperature in the heat treatment step at the sheet resistance measurement location based on the calculated temperature conversion function.

In this case, for example, as defined in claim 6, the object to be monitored is configured by forming a metal-containing film on a silicon substrate via an insulating layer.
For example, as defined in claim 7, the metal-containing film is made of a metal film or a metal nitride film.
For example, as defined in claim 8, the predetermined temperature of the heat treatment is in a range of 200 to 500 ° C.

  The invention according to claim 9 is a single wafer heat treatment apparatus for performing heat treatment on an object to be processed, a processing container capable of accommodating the object to be processed, a support portion for supporting the object to be processed, and the processing container. A gas supply means for introducing a predetermined gas into the inside, an exhaust means for exhausting the inside of the processing container, and an outside of the processing container, and is divided into a plurality of heating zones so that control can be performed for each heating zone. And a temperature control unit that controls electric power supplied to each heating zone by controlling the heating unit based on a temperature distribution obtained by the invention according to any one of claims 5 to 8. A single wafer heat treatment apparatus.

According to the method for forming the temperature conversion function, the method for calculating the temperature distribution, and the single-wafer heat treatment apparatus according to the present invention, the following excellent effects can be obtained.
According to the method of the present invention, since the sheet resistance value before the heat treatment affects the sheet resistance value after the heat treatment is removed, an accurate and accurate heat treatment temperature and its temperature distribution can be obtained. it can. In particular, for example, the heat treatment temperature in a low temperature range of about 200 to 500 ° C. and the accuracy of the temperature distribution can be improved.
According to the apparatus of the present invention, the in-plane uniformity of the heat treatment temperature can be made extremely high by performing temperature control during the heat treatment based on the heat treatment temperature or temperature distribution with high accuracy obtained as described above. .

Hereinafter, an embodiment of a method for forming a temperature conversion function, a method for calculating a temperature distribution, and a single wafer heat treatment apparatus according to the present invention will be described in detail with reference to the accompanying drawings.
FIG. 1 is a sectional view showing an example of a single wafer type heat treatment apparatus used for carrying out the method of the present invention, FIG. 2 is a plan view showing heating means of the apparatus shown in FIG. 1, and FIG. It is sectional drawing shown.
First, the single wafer type heat treatment apparatus will be described. As shown in FIGS. 1 and 2, the heat treatment apparatus 2 includes a processing vessel 4 made of, for example, a rectangular shape made of quartz. An opening 6 for introducing, for example, a semiconductor wafer 5 as an object to be processed is formed on one side of the processing container 4, and a flange portion 8 is formed around the opening 6. A plurality of projections 12 made of, for example, quartz are erected on the bottom of the processing vessel 4 as support portions 10 for supporting the wafer 5 introduced into the vessel. 12 supports the periphery of the back surface of the wafer 5.

Further, a transfer pick (not shown) that enters the processing container 4 is prevented from interfering with the projection 12, and the transfer pick is inserted with the pick inserted between the projections 12. The wafer 5 is transferred by moving up and down.
A gas supply port 14 is provided at one end of the processing container 4 as a gas supply means for introducing a predetermined gas required therein, and the atmosphere in the processing container 4 is, for example, a vacuum. An exhaust port 16 is provided as an exhaust means for exhausting air.
Further, a cooling plate 20 is provided on the end surface of the opening 6 of the processing container 4 with a seal member 18 such as an O-ring interposed therebetween so as to be in contact with the flange portion 8. And in this cooling plate 20, the cooling water channel 22 which flows a cooling water is provided, and the said sealing member 18 is cooled. The cooling plate 20 is fastened and fixed by, for example, an aluminum casing 24 surrounding the outside of the processing container 4 with bolts 26 or the like. At this time, the flange portion 8 of the processing container 4 is also fixed at the end of the casing 24. It has come to be able to do.

  A gate valve 28 that is opened and closed in an airtight manner when the wafer W is loaded and unloaded is provided at a portion facing the opening 6. A heating means 30 for heating the wafer 5 is provided immediately outside the processing container 4 so as to surround the processing container 4. Specifically, the heating means 30 is formed by a resistance heater 32 made of Kanthal wire provided over the entire upper surface side and lower surface side of the processing container 4. The resistance heater 32 may also be provided on the outer side surface of the processing container 4. The resistance heater 32 is divided into a plurality of heating zones, that is, three heating zones 32A, 32B, and 32C in this case. For example, the temperature control unit 34 including a microcomputer or the like inputs the heating heaters 32A to 32C. Power to be controlled. Here, the three heating zones include a front heating zone 32A, a central heating zone 32B, and a rear heating zone 32C. Thermocouples 36A, 36B, and 36C are provided for each of the heating zones 32A to 32C, and the detected temperature can be input to the temperature controller 34.

When performing heat treatment of a semiconductor wafer or the like using the single-wafer type heat treatment apparatus 2 formed in this manner, prior to this, it is confirmed whether or not the wafer can be heated with good in-plane temperature uniformity. There must be. Also, the confirmation of the uniformity of the in-plane temperature is performed regularly or irregularly as necessary.
An example of a monitoring object to be used for confirming the uniformity of the in-plane temperature, for example, a monitoring wafer is shown in FIG. That is, the monitor wafer 5M is formed by laminating the metal-containing film 44 on the silicon substrate 40 via the insulating layer 42 made of, for example, SiO ₂ . The insulating layer 42 has a function of preventing the metal-containing film 44 from being silicided. As the metal-containing film 44, in addition to a metal film such as Ti, W, Cu, Co, and Ni, a nitride film of these metals, for example, a TiN metal nitride film can be used. Is used.

<Process for obtaining heat treatment temperature from sheet resistance value>
Next, a process (method) for obtaining the heat treatment temperature from the sheet resistance value will be described.
FIG. 4 is a graph showing the relationship between the heat treatment temperature before correction and the increase in sheet resistance value: ΔRs. In general, metal materials such as Ti, W, TiN, Ni, Co, and Cu that are generally used as film forming materials for semiconductor wafers are easily oxidized and nitrided even at low temperatures. When this reaction occurs, the sheet resistance value Rs increases. There is a phenomenon. Therefore, using the monitor wafer 5M as shown in FIG. 3, the sheet resistance value before and after the heat treatment is measured in advance, and the increase (difference value) ΔRs in the sheet resistance value at this time and the heat treatment are measured. A relationship with the temperature T is obtained in advance. An example of the correlation created in this way is shown in FIG. The process conditions during this heat treatment were a TiN film as the metal-containing film, and an annealing treatment of 300 sec was performed while supplying 0.5 slm O ₂ gas.

At this time, a correlation function as shown in FIG. 4, that is, an approximate expression of the temperature conversion function, is expressed as the following Expression 1.
ΔRs = 0.1600096667967257e ^{0.014943307967261XT} ... Formula 1
First, a reference temperature conversion function as shown in FIG. 4 is obtained, and thereafter, for example, the monitor wafer as described above is heat-treated periodically or irregularly as necessary. If the sheet resistance value ΔRs before and after the heat treatment is obtained and applied to the graph shown in FIG. 4 or Formula 1, the temperature and temperature distribution at the time of processing at the location where the sheet resistance value is measured can be obtained.

However, as described above, the sheet resistance value after the heat treatment does not actually change depending on the heat treatment temperature, but also slightly depends on the sheet resistance value (initial sheet resistance value) before the heat treatment. Since it varies, the temperature and temperature distribution obtained with reference to Equation 1 shown in FIG. 4 may have a considerable error from the actual temperature and temperature distribution.
Therefore, in the method of the present invention, the difference between the initial resistance value and the sheet resistance value before and after heat treatment based on the amount of sheet resistance value that affects the sheet resistance value after heat treatment, that is, the sheet resistance value amount. The value is corrected to obtain a correction difference value, and a temperature conversion function is obtained based on the correction difference value.

  Specifically, first, it is verified how much the initial resistance value affects the increase in the sheet resistance value after the heat treatment. FIG. 5 is a graph showing the relationship between the initial resistance value Rs when the heat treatment temperature is 300 ° C. and the increase ΔRs of the sheet resistance value before and after the heat treatment. FIG. 6 is a graph showing the relationship between the initial resistance value Rs when the heat treatment temperature is 350 ° C. and the increase ΔRs of the sheet resistance value before and after the heat treatment. FIG. 7 is a graph showing the relationship between the initial resistance value Rs when the heat treatment temperature is 400 ° C. and the increment ΔRs of the sheet resistance value before and after the heat treatment.

In each heat treatment shown in FIG. 5 to FIG. 7, an annealing process of 300 sec is performed while supplying O ₂ gas at a flow rate of 0.5 slm. The sheet resistance value is measured at 49 points. Here, the increase ΔRs of the sheet resistance value is naturally obtained as a difference value between the sheet resistance values before and after the heat treatment. In each graph shown in FIG. 5 to FIG. 7, each straight line is a trend line obtained by the least square method based on the sheet resistance value of 49 points, and each trend line is “y” at 300 ° C. = 0.4232x-18.455 ", 350 [deg.] C. is expressed as" y = 0.5378x-14.997 ", and 400 [deg.] C. is expressed as" y = 2.6443x-96.536 ". It should be noted that in the above trend directly, x is the initial sheet resistance value Rs, and y is the increase ΔRs of the sheet resistance value.

  As apparent from FIGS. 5 to 7, as the heat treatment temperature increases to 300 ° C., 350 ° C., and 400 ° C., the inclination of the trend line is “0.4232”, “0.5378”, and “2. The size increases in the order of 0643 ″. As a result, it can be confirmed that the initial sheet resistance value of the wafer significantly affects the increase of the sheet resistance value after the heat treatment. In other words, for example, even if the wafer is heat-treated at the same temperature, if there is a variation in the initial sheet resistance value, the sheet resistance value after the heat treatment is expressed in a state where the variation is expanded. Here, the standard difference value is obtained by compensating the amount of sheet resistance that the initial sheet resistance value affects the sheet resistance value after the heat treatment with respect to the difference value.

Next, the obtained standard difference value is averaged to obtain a correction difference value (correction ΔRs) at each heat treatment temperature. Further, a temperature conversion function that is a correlation between the temperature in the heat treatment step and the correction difference value is obtained based on the obtained correction difference value at each heat treatment temperature.
First, the standard difference value is obtained by compensating the sheet resistance value amount that the initial sheet resistance value affects the sheet resistance value after the heat treatment from the increment ΔRs of each sheet resistance value in FIGS. Ask. Specifically, in each of the graphs of FIGS. 5 to 7, the difference between the average value of the 49 sheet resistance increases and the temperature conversion function is subtracted from or added to the increase of each sheet resistance value. To compensate. As an example, the compensation operation will be described with reference to FIG. 5 showing an increase in the sheet resistance value when the heat treatment temperature is 300.degree.

First, in FIG. 5, if the average value of the increase in sheet resistance value at all 49 points of measurement is “AV”, the difference between the average value AV and the trend line is defined as the above-mentioned sheet resistance value amount. Is done. Then, the sheet resistance value amount is subtracted from the increase ΔRs of the sheet resistance value at the corresponding point (a region on the right side of the intersection O1 where the average value AV and the trend line intersect) or added (the average value AV and the trend line). To the left of the intersection O1). Specifically, the sheet resistance value amount at the point P1 (x1, y1) in the region on the right side of the intersection O1 is “| Δy1 |” (absolute value), and the standard difference value Δm1 at this point P1 is expressed by the following equation. It becomes like this.
Δm1 = y1- | Δy1 |
Further, the sheet resistance value amount at the point P2 (x2, y2) in the region on the left side of the intersection O1 is “| Δy2 |”, and the standard difference value Δm2 at this point P2 is expressed by the following equation.
Δm2 = y2 + | Δy2 |
In this way, 49 standard difference values Δm1, Δm2,..., Δm49 are obtained. And the average value of the said standard difference value is calculated | required like a following formula, and this is defined as correction | amendment difference value (correction (DELTA) Rs).
Correction ΔRs = (Δm1 + Δm2 +... + Δm48 + Δm49) / 49
In this way, the correction difference value (correction ΔRs) at the temperature of 300 ° C. is obtained.

Then, the correction difference value (correction ΔRs) at 350 ° C. shown in FIG. 6 and the correction difference value (correction ΔRs) at 400 ° C. shown in FIG. Then, a temperature conversion function that is a correlation with the heat treatment temperature T is approximately obtained based on the three correction difference values (correction ΔRs) of 300 ° C., 350 ° C., and 400 ° C. FIG. 8 is a graph showing the temperature conversion function obtained as described above, that is, the relationship between the heat treatment temperature and the correction difference value. Here, the correction difference value at 300 ° C. is “14.27”, the correction difference value at 350 ° C. is “27.22”, and the correction difference value at 400 ° C. is “67.43”. The approximated temperature conversion function is the following equation (2).
Correction ΔRs = 0.1637660569041313e ^{0.0148700248044760xT}
... Formula 2
As is clear from comparison between FIG. 4 and FIG. 8, the temperature conversion function shown in FIG. 8 compensates for the increase in the sheet resistance value after the heat treatment caused by the initial sheet resistance value.

Here, a series of operations until the above-described temperature conversion function is obtained will be generally described based on a flow for obtaining the temperature conversion function shown in FIG.
First, a plurality of monitor wafers having, for example, a TiN film formed as a metal-containing film on the surface, in this case, a total of three monitor wafers for 300 ° C., 350 ° C. and 400 ° C. are prepared (S1).
Next, before the heat treatment, the sheet resistance values on the surfaces of the three monitor wafers are measured at a plurality of locations, for example, 49 locations (S2).
Next, heat treatment is performed at different temperatures on the three monitor wafers (S3). Here, as described above, annealing or the like is performed at different temperatures of 300 ° C., 350 ° C., and 400 ° C. In this case, the process conditions other than the process temperature, particularly the process time, are set to be the same.

Next, each of the monitor wafers after the heat treatment is cooled to room temperature, and the sheet resistance value of the TiN film on the surface is measured (S4). In this case, the measurement location and the number of measurement points are the same as in the measurement of the sheet resistance value before the heat treatment (step S2).
Next, the difference value ΔRs of the sheet resistance values before and after the heat treatment obtained in the above steps S2 and S4 is obtained at 49 points for each monitor wafer (S5). By plotting the difference value ΔRs on a graph, the graphs shown in FIGS. 5 to 7 are obtained.
Next, the sheet resistance values (Δy1 and Δy2 in FIG. 5) that the sheet resistance value before the heat treatment (initial sheet resistance value) affects the sheet resistance value after the heat treatment are compensated for each difference value. Thus, 49 standard difference values are obtained for each heat treatment temperature (S6). This standard difference value corresponds to Δm1 to Δm49 shown above.

Next, the standard difference value is averaged for each heat treatment temperature of 300 ° C., 350 ° C., and 400 ° C. to obtain a corrected difference value at each heat treatment temperature (S7).
Next, a temperature conversion function indicating the correlation between the heat treatment temperature T and the correction difference value (correction ΔRs) as shown in FIG. 8 is obtained based on each of the correction difference values, here, the three correction difference values ( S8).
The above-described temperature conversion function forming operation as shown in FIG. 8 is performed when the heat treatment apparatus is started up or when internal components are replaced, and the obtained temperature conversion function as shown in FIG. For example, it is stored in the temperature controller 34 shown in FIG.

Next, the inspection of the temperature distribution on the wafer that is performed regularly or irregularly using the temperature conversion function will be described.
For example, this inspection is performed every time a predetermined number of product wafers, for example, 4 slots and 100 product wafers are heat-treated. FIG. 10 shows a flow for inspecting the temperature distribution of the semiconductor wafer. The flow shown in FIG. 10 is substantially the same as the flow shown in FIG. 9 except that the temperature distribution is obtained using the temperature conversion function obtained in the flow shown in FIG. 9 in the last step. Here, a case where the temperature distribution when the heat treatment temperature is 350 ° C. is obtained will be described as an example.

First, a monitoring wafer for 350 ° C. having, for example, a TiN film formed as a metal-containing film on the surface is prepared (S21).
Next, before the heat treatment, the sheet resistance value on the surface of the monitor wafer is measured at a plurality of locations, for example, 49 locations (S22).
Next, a heat treatment is performed on the monitor wafer at a predetermined temperature, here 350 ° C. (S23). Here, as described above, annealing or the like is performed at a temperature of 350 ° C. In this case, the process conditions other than the process temperature, in particular the process time, are set to be the same as those in the heat treatment when the temperature conversion function is obtained.

Next, the monitor wafer after the heat treatment is cooled to room temperature, and the sheet resistance value of the TiN film on this surface is measured (S24). In this case, the measurement location and the number of measurement points are the same as in the measurement of the sheet resistance value before the heat treatment (step S22).
Next, the difference value ΔRs between the sheet resistance values before and after the heat treatment obtained in steps S22 and S24 is obtained at 49 points for the monitor wafer (S25). By plotting the difference value ΔRs on a graph, the graphs shown in FIGS. 5 to 7 are obtained.
Next, the sheet resistance value before the heat treatment (initial sheet resistance value) affects the sheet resistance value after the heat treatment (same as the case where Δy1 and Δy2 in FIG. 5 are respectively determined), 49 standard difference values are obtained for each heat treatment temperature by compensating for each difference value (S6). This standard difference value corresponds to Δm1 to Δm49 shown above.

Next, by referring to the standard difference value by applying it to the temperature conversion function shown in FIG. 8, the heat treatment temperature T of each of the 49 sheet resistance value measurement locations is obtained (S27). In this case, the standard difference value corresponds to the correction difference value (correction ΔRs) on the vertical axis in FIG. The temperature distribution in the wafer is obtained by plotting the 49 heat treatment temperatures thus obtained on the wafer map.
As described above, since the sheet resistance value that affects the sheet resistance value after the heat treatment is removed from the sheet resistance value before the heat treatment, it is possible to obtain a highly accurate and appropriate heat treatment temperature and its temperature distribution. In particular, for example, the heat treatment temperature in a low temperature range of about 200 to 500 ° C. and the accuracy of the temperature distribution can be improved.
Then, referring to the temperature distribution obtained here, the temperature control unit 34 (see FIG. 1) moves the temperature control unit 34 to each of the heating zones 32A to 32C of the heating means 30 so that the temperature distribution becomes more uniform. The temperature is controlled by individually determining the power to be supplied. Actually, thermocouples 36A to 36C are provided in each heating zone, and the temperature of the thermocouple in each heating zone is set from the temperature distribution obtained here.

  Here, the temperature distribution state of the wafer obtained by using each temperature conversion function shown in FIGS. 4 and 8 will be described. FIG. 11 is a diagram showing the temperature distribution of the wafer obtained using the temperature conversion function before and after correction. 11A shows a case where the temperature conversion function before correction shown in FIG. 4 is used, and FIG. 11B shows a case where the temperature conversion function after correction shown in FIG. 8 is used. The heat treatment temperatures are 300 ° C., 350 ° C., and 400 ° C., respectively. As shown in the figure, it is clear that the temperature distribution is clearly different before and after the correction. In addition, the number in a figure shows the difference value of sheet resistance value, or a correction | amendment difference value (standard difference value).

Next, whether or not the temperature distribution of the wafer obtained by using the corrected temperature conversion function shown in FIG. 8 reflects an appropriate temperature will be described.
FIG. 12 is a graph showing the temperature of the thermocouple attached to the central portion and the peripheral portion of the surface of the monitor wafer when the wafer temperature distribution verification experiment is performed, and FIG. 13 is a diagram after the heat treatment of the monitor wafer shown in FIG. FIG. 9 is a diagram showing a temperature distribution obtained using the corrected temperature conversion function shown in FIG. Here, the heat treatment temperature was set to 350 ° C. and 362 ° C., respectively, and the verification experiment was performed twice.
In FIG. 12, the curve A1 shows the transition of the detected temperature of the thermocouple at the wafer center when the set temperature is 350 ° C., and the curve A2 shows the detected temperature of the thermocouple at the periphery of the wafer when the set temperature is 350 ° C. Curve B1 shows the transition of the detected temperature of the thermocouple at the center of the wafer when the set temperature is 362 ° C., and curve B2 shows the detected temperature of the thermocouple at the periphery of the wafer when the set temperature is 362 ° C. As can be seen from FIG. 12, the curve A1 and the curve B1 stably show the set temperatures of 350 ° C. and 362 ° C., respectively. Curves A2 and B2 show transitions at 345 ° C. and 380 ° C., respectively.

On the other hand, the temperature distribution of the two monitor wafers shown in FIG. 12 is shown in FIG. 13, and FIG. 13A shows the temperature distribution when the heat treatment temperature is 350 ° C. FIG. B) shows the temperature distribution at the heat treatment temperature or 362 ° C. In FIG. 13, the installation positions of the thermocouples corresponding to the curves A1, A2, B1, and B2 in FIG. 12 are indicated by A1, A2, B1, and B2. As shown in FIG. 13A, this temperature distribution shows that the central portion (position A1) has a temperature of about 352 ° C., and the temperature gradually decreases toward the periphery of the wafer. A2 indicates about 345 ° C. As a result, it was confirmed that FIG. 13A shows an actual substantially appropriate temperature distribution of the wafer temperature.
As shown in FIG. 13B, this temperature distribution shows that the central portion (position B1) is approximately 362 ° C., and the temperature decreases or increases very gradually toward the periphery of the wafer. The position B2 indicates about 378 ° C. As a result, it can be confirmed that FIG. 13B shows an actual substantially appropriate temperature distribution of the wafer temperature.

Next, based on the temperature distribution of the monitor wafer obtained as shown in FIG. 13, the control thermocouples of the heating zones 32A, 32B, 32C of the heating means 30 shown in FIG. The temperature distribution of the wafer when the temperature setting is actually individually controlled will be described.
FIG. 14 is a graph showing the temperature distribution in the wafer diameter direction when the temperature setting of each heating zone is actually individually controlled based on the temperature distribution of the monitor wafer. In the figure, curve X1 shows the case where the front heating zone (F) is set to “+ 0 ° C.” and the rear heating zone (R) is set to “+ 0 ° C.” with the center heating zone as the center, and curve X2 is the center The front heating zone (F) is set to “+ 20 ° C.” with the heating zone as the center, and the rear heating zone (R) is set to “−20 ° C.”, and the curve X3 is the front with the center heating zone as the center. The case where the heating zone (F) is set to “+ 15 ° C.” and the rear heating zone (R) is set to “−15 ° C.” is shown. Curve X3 shows that the front heating zone (F) is centered on the central heating zone. The case where “+ 20 ° C.” is set and the rear heating zone (R) is set to “+ 0 ° C.” is shown.

As is apparent from the curves X1 to X4, as shown by the curve X3, the set temperature of the front heating zone 32A (F) is set to “+ 15 ° C.” with respect to the set temperature of the central heating zone 32B. It was found that the in-plane uniformity of the wafer temperature can be maximized by setting the set temperature of 32C (R) to “−15 ° C.”.
Thus, from the temperature distribution obtained as shown in FIG. 13, the temperature setting of each of the heating zones 32A to 32C of the heating means 32 can be optimized and controlled so as to make it uniform.
Further, when a plurality of wafers, for example, six wafers (two on the way are dummy wafers) are sequentially processed in a state where the heating zones 32A to 32C are controlled as indicated by a curve X3 in FIG. The actual heat treatment temperatures are 355.1 ° C. (first sheet), 355.7 ° C. (second sheet), 355.5 ° C. (third sheet), and 356.4 ° C. (sixth sheet). It was shown that the reproducibility was good.

In the above embodiment, the sheet resistance value was measured at 49 points. However, this measurement point is not particularly limited, and the more the measurement points, the higher the accuracy. When the sheet resistance value is measured by, for example, one measurement point may be used.
Further, here, an example of an apparatus in which the processing container 4 is formed of quartz in a rectangular shape has been described. However, the present invention is not limited to this, and a support unit made of a mounting table or the like in a cylindrical processing container made of aluminum or the like. Of course, the present invention can also be applied to a heat treatment apparatus that performs heat treatment by heating with a heating lamp or a heating means including a resistance heater embedded in a mounting table.
Further, the form of the heating zone is not limited to the strip shape as shown in FIG. 2, and may be formed as, for example, a concentric circle or an assembly of circular heating zones.
The object to be processed is not limited to a semiconductor wafer, and the present invention can of course be applied to an LCD substrate, a glass substrate, and the like.

It is a cross-sectional block diagram which shows an example of the single wafer type heat processing apparatus used for implementation of the method of this invention. It is a top view which shows the heating means of the apparatus shown in FIG. It is sectional drawing which shows the to-be-processed object for a monitor. It is a graph which shows the relationship between the heat processing temperature before correction | amendment, and the increase in a sheet resistance value. It is a graph which shows the relationship between initial resistance value Rs in the heat processing temperature of 300 degreeC, and the increment of the sheet resistance value before and behind heat processing. It is a graph which shows the relationship between the initial resistance value Rs in the heat processing temperature of 350 degreeC, and the increase in the sheet resistance value before and behind heat processing. It is a graph which shows the relationship between the initial resistance value in the heat processing temperature of 400 degreeC, and the increment of the sheet resistance value before and behind heat processing. It is a graph which shows a temperature conversion function (The relationship between heat processing temperature and a correction | amendment difference value). It is a flow which shows the process of calculating | requiring a temperature conversion function. It is a figure which shows the flow in the case of test | inspecting the temperature distribution of a semiconductor wafer. It is a figure which shows the temperature distribution of the wafer calculated | required using the temperature conversion function before correction | amendment and after correction | amendment. It is a graph which shows the temperature of the thermocouple attached to the surface center part and peripheral part of the wafer for a monitor when the verification experiment of the temperature distribution of a wafer was conducted. It is a figure which shows the temperature distribution calculated | required using the temperature conversion function after correction | amendment after the heat processing of the monitor wafer shown in FIG. It is a graph which shows the temperature distribution in the wafer diameter direction when the input electric power to each heating zone is actually controlled individually based on the temperature distribution of the monitor wafer.

Explanation of symbols

2 Heat treatment apparatus 4 Processing container 5 Object to be processed 5M Monitor wafer (Monitor object)
14 Gas supply port (gas supply means)
16 Exhaust port (exhaust means)
30 Heating means 32 Resistance heater 32A to 32C Heating zone 34 Power control unit

Claims (9)

In the method of forming a temperature conversion function for determining the exposed temperature of the monitor object from the sheet resistance value before and after the heat treatment of the monitor object having a metal-containing film formed on the surface,
A step of preparing a plurality of monitoring objects having a metal-containing film formed on the surface;
A pre-treatment sheet resistance measurement step of measuring sheet resistance at one or a plurality of locations of the metal-containing film with respect to each monitor object;
A heat treatment step of heat-treating each of the plurality of monitoring objects to different temperatures; and
A post-treatment sheet resistance measurement step for measuring the sheet resistance at the same location as the location where the sheet resistance was measured in the pre-treatment sheet resistance measurement step for the metal-containing film of the monitor target after the heat treatment,
A difference value calculating step for obtaining a difference value between the sheet resistance value obtained in the pre-treatment sheet resistance measurement step and the sheet resistance value obtained in the post-treatment sheet resistance measurement step;
A step of obtaining a standard difference value by compensating the amount of sheet resistance that the sheet resistance value before heat treatment affects the sheet resistance value after heat treatment with respect to the difference value;
A correction difference value calculating step for obtaining a correction difference value at each of the heat treatment temperatures by averaging the standard difference values;
Obtaining a temperature conversion function that is a correlation between the temperature in the heat treatment step and the corrected difference value based on the obtained one or more corrected difference values;
A method for forming a temperature conversion function for a monitoring object.   The temperature conversion function of the monitor object according to claim 1, wherein the monitor object is formed by forming a metal-containing film on a silicon substrate via an insulating layer. Forming method.   3. The method of forming a temperature conversion function for a monitor object according to claim 1, wherein the metal-containing film is made of a metal film or a metal nitride film.   4. The method for forming a temperature conversion function of a monitor object according to claim 1, wherein the predetermined temperature of the heat treatment is in a range of 200 to 500 [deg.] C. In the temperature distribution calculation method for obtaining the temperature distribution of the monitor object to be exposed from the sheet resistance value before and after the heat treatment of the monitor object having a metal-containing film formed on the surface,
A step of preparing a monitor object having a metal-containing film formed on the surface;
A pre-treatment sheet resistance measurement step for measuring the sheet resistance at one or more locations of the metal-containing film with respect to the monitor object;
A heat treatment step of subjecting the monitoring object to a predetermined temperature and heat-treating;
A post-treatment sheet resistance measurement step for measuring the sheet resistance at the same location as the location where the sheet resistance was measured in the pre-treatment sheet resistance measurement step for the metal-containing film of the monitor target after the heat treatment,
A difference value calculating step for obtaining a difference value between the sheet resistance value obtained in the pre-treatment sheet resistance measurement step and the sheet resistance value obtained in the post-treatment sheet resistance measurement step;
A step of obtaining a standard difference value by compensating a sheet resistance value amount in which the sheet resistance value before the heat treatment affects the sheet resistance value after the heat treatment;
A step of obtaining a temperature in the heat treatment step of the sheet resistance measurement portion based on the obtained standard difference value and a temperature conversion function obtained in advance in the invention according to claim 1;
A method for calculating a temperature distribution of a monitoring object.   6. The calculation of the temperature distribution of the monitor target object according to claim 5, wherein the monitor target object is formed by forming a metal-containing film on a silicon substrate via an insulating layer. Method.   7. The method for calculating a temperature distribution of a monitor object according to claim 5, wherein the metal-containing film is made of a metal film or a metal nitride film.   The method for calculating a temperature distribution of a monitor object according to any one of claims 5 to 7, wherein the predetermined temperature of the heat treatment is in a range of 200 to 500 ° C. In a single-wafer type heat treatment apparatus that performs heat treatment on a workpiece,
A processing container capable of accommodating the object to be processed;
A support part for supporting the object to be processed;
Gas supply means for introducing a predetermined gas into the processing container;
Exhaust means for exhausting the inside of the processing container;
A heating means provided outside the processing vessel and divided into a plurality of heating zones so as to be controlled for each heating zone;
A power control unit that controls power to be supplied to each heating zone by controlling the heating unit based on the temperature distribution obtained by the invention according to any one of claims 5 to 8;
A single-wafer type heat treatment apparatus.

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