JP2007081348A - Method for controlling temperature of thermal process, method of thermal process of substrate and device of thermal process of substrate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a temperature control method, a method of thermal process of a semiconductor substrate and a device of thermal process which can improve a uniformity of the in-plane temperature of the substrate during a rapid thermal process using lamp heating. <P>SOLUTION: In the first place, calibration data are acquired in temperature measuring positions on the substrate by associating the thickness of an oxide film formed by thermal process and the set temperature of thermal process. In the second place, the thickness of the oxide film which is formed on the substrate is measured in the temperature measuring positions on the substrate which is subjected to thermal process at a specific set temperature of thermal process. Then set temperature T of thermal process corresponding to the measured thickness of the oxide film and set temperature Tm' of thermal process corresponding to the thickness of the oxide film which should be acquired at the specific set temperature of thermal process are acquired from the calibration data. Temperature correction values of temperature probes are acquired according to these temperature differences. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a precise temperature adjustment method for a heat treatment apparatus employing a rapid thermal process (RTP) method for heat treating a semiconductor substrate widely used in a semiconductor integrated circuit manufacturing process, a substrate heat treatment method, and a substrate heat treatment apparatus. About.

  In recent years, with the miniaturization of element patterns constituting semiconductor devices, it is necessary to form a thin gate insulating film, a shallow impurity diffusion region, and the like uniformly and stably without reducing throughput. . For this reason, in the manufacturing process of a semiconductor device, an RTP heat treatment apparatus that performs a short-time heat treatment in a single wafer type is used. As this type of apparatus, a lamp-type RTP apparatus that heat-treats a semiconductor substrate with energy radiated from a substrate heating lamp such as a halogen lamp has been developed and is widely used.

  FIG. 1 shows a longitudinal sectional view of an essential part of the lamp type RTP heat treatment apparatus 1 (hereinafter referred to as heat treatment apparatus 1). The heat treatment apparatus 1 is a lamp in which about 20 to 300 tungsten halogen lamps are disposed through a quartz plate 4 above a cylindrical chamber 3 in which a semiconductor substrate (hereinafter simply referred to as a substrate) is heat treated. Unit 2 is provided.

A gas introduction path 8 for introducing a process gas into the chamber 3 is communicated with the side wall of the chamber 3, and a gas outlet for discharging the gas in the chamber 3 is disposed on the side wall at a position facing the gas introduction path 8. Road 9 is in communication. For example, when a heat treatment for forming a specific material film such as an oxide film or a nitride film on the substrate 10 is performed, a substrate into which impurities are implanted by introducing a material gas corresponding to the material film from the gas introduction path 8. When the activation annealing process 10 is performed, an inert gas such as N ₂ gas or Ar gas is introduced from the gas introduction path 8.

  A support ring 5 made of a heat-resistant material such as silicon carbide having an inner diameter slightly smaller than the diameter of the substrate 10 to be heat-treated is disposed in the horizontal plane in the chamber 3. The support ring 5 is supported by a cylindrical rotary cylinder 6 protruding vertically upward from the lower surface of the chamber 3, and the edge portion of the substrate 10 is placed on the inner edge portion of the support ring 5. The rotating cylinder 6 is supported on the bottom surface of the chamber 3 via a bearing (not shown) that can rotate in a horizontal plane, and the heat treatment is performed while rotating the substrate 10. The substrate 10 is carried in / out through a substrate inlet / outlet (not shown) provided on the side wall of the chamber 3 so as to be freely opened and closed.

  Further, at the bottom surface of the chamber 3, one end of a plurality of temperature probes 7 made of optical fiber probes arranged at appropriate intervals is exposed in a region inside the rotary cylinder 6, and is exposed from the bottom surface of the substrate 10. A temperature measuring device such as a pyrometer (not shown) that receives the emitted light (radiant heat) and is connected to the other end of the optical temperature probe 7 changes the temperature of the substrate surface during the heat treatment from the center to the periphery of the substrate. Is measured.

  FIG. 2 is a diagram showing a general heat treatment sequence used for heat treatment in the heat treatment apparatus 1 described above. As shown in FIG. 2, the heat treatment sequence includes a temperature raising process, a main process for maintaining a predetermined heat treatment temperature Tm for a predetermined time t, and a temperature lowering process. In each process, the lamp power balance is determined by the lamps of a plurality of lamps installed in a region opposed to each temperature probe 7 by the temperature control means 20 based on the temperature measured by each temperature probe 7 in the apparatus of FIG. By controlling the power, the temperature in the substrate surface is adjusted to be uniform.

  Various techniques for improving the temperature distribution in the substrate surface have been proposed. For example, the temperature of the semiconductor substrate is increased over time by dividing it into a plurality of stages with different heating rates in the heating process. A method has been proposed in which the power balance of the lamp is set for each temperature raising stage, and the temperature raising speed of each temperature raising stage is sequentially decelerated until reaching the apparatus setting temperature of the main process (for example, Patent Document 1).

In this technique, the power balance of the lamp is adjusted based on the evaluation result obtained from the dummy substrate with respect to the heat load of the temperature rising process for raising the temperature at a constant speed and the main process for holding the given temperature for a given time. . For example, a lamp power balance condition is set by forming an oxide film by RTP on the surface of a dummy substrate and evaluating the in-plane distribution of the thickness of the oxide film.
JP 2000-331949 A

  However, if the temperature raising process is divided into a plurality of stages, the temperature of the main process in FIG. 2 in the region of 500 ° C. to 1200 ° C. may cause a temperature difference of 10 degrees or more in the substrate surface. Will occur. Such a temperature variation causes a characteristic variation in a semiconductor device that will be further miniaturized in the future. Therefore, there is a demand for further uniform temperature.

  The present invention has been proposed in view of the above-described conventional circumstances, and is a temperature adjusting method for removing in-plane non-uniformity of a substrate at a heat treatment temperature as described above in short-time heat treatment using lamp heating, and heat treatment of a substrate. It is an object to provide a method and a heat treatment apparatus.

  In order to solve the above problems, the present invention employs the following means. That is, the present invention is a method for adjusting a heat treatment temperature applied to a heat treatment apparatus that performs temperature control based on temperatures measured at a plurality of positions on the same substrate and performs heat treatment of the substrate. Calibration data in which a physical quantity that varies according to the heat treatment set temperature is associated is acquired. Next, the physical quantity is measured at each temperature measurement position of the substrate that has been heat-treated at a specific heat treatment set temperature. Then, from the calibration data, the heat treatment set temperature corresponding to the measured physical quantity and the heat treatment set temperature corresponding to the physical quantity to be obtained at the specific heat treatment set temperature are obtained, and each physical quantity measurement is performed based on these temperature differences. The temperature correction value of the temperature probe corresponding to the position is obtained. The calibration data is preferably acquired at each temperature measurement position. Further, as the calibration data, data in which the average value of the physical quantity in the substrate surface is associated with the heat treatment set temperature can be used.

  The physical quantity is, for example, the thickness of the dry oxide film or wet oxide film formed on the substrate by the heat treatment, or the sheet resistance of the impurity diffusion region on the substrate activated by the heat treatment.

  By performing the heat treatment of the substrate with the heat treatment apparatus in which the heat treatment temperature is adjusted by the above method, the substrate can be uniformly heat treated.

  On the other hand, in another aspect, the present invention can provide a heat treatment apparatus suitable for carrying out the above-described method for adjusting a heat treatment temperature. That is, the heat treatment apparatus according to the present invention associates a plurality of heating means for heating the substrate, a plurality of temperature probes for measuring the temperature of the substrate, a physical quantity that varies according to the heat treatment, and a heat treatment set temperature. An arithmetic processing unit is provided for correcting the temperature measured by each temperature probe based on the temperature correction value of each temperature probe calculated from the calibration data. And the heating amount of each said heating means is controlled based on the temperature which each temperature probe correct | amended based on the said temperature correction value acquired.

  According to the present invention, the uniformity of the in-plane temperature of the substrate can be improved, and the temperature difference in the substrate surface can be suppressed to 4 degrees or less. As a result, variations in characteristics and reliability of the semiconductor device in the substrate surface can be reduced.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a schematic view showing a main configuration of a heat treatment apparatus according to this embodiment. This heat treatment apparatus has a metal chamber 3 similar to the conventional heat treatment apparatus described above, and is provided with a number of tungsten halogen lamps or the like serving as a lamp light source via a quartz plate 4 in the upper part of the chamber 3. A lamp unit 2 is provided. In the chamber 3, a support ring 5 that horizontally supports the substrate 10 and a plurality of temperature probes 7 are provided on the bottom surface of the chamber 3 (the back surface side of the substrate 10). The rotating cylinder 6 on which the support ring 5 is placed is rotated by a driving mechanism (not shown) to rotate the substrate 10 in the chamber 3 at, for example, 90 to 250 rotations / minute. The chamber 3 is provided with a gas introduction path 8 for introducing a process gas and a gas outlet path 9 for exhausting the introduced process gas.

  Radiation light from the back surface of the substrate 10 enters the temperature probe 7, and the temperature of the substrate 10 is measured by converting the radiation light into temperature. Further, in order to measure the temperature and temperature distribution in the surface of the substrate 10, a plurality of temperature probes 7 are installed from a position facing the center of the substrate 10 to a position facing the outer periphery.

  In the heat treatment apparatus 1, the heat treatment sequence when performing heat treatment is as shown in FIG.

  The method for adjusting the heat treatment temperature according to the present invention utilizes the fact that the film thickness of the thermal oxide film grown on the surface of the substrate 10 in response to the heat treatment sensitively reflects the heat treatment temperature. First, dry oxygen is introduced into the chamber 3 at a constant flow rate, and the time t for maintaining the heat treatment temperature Tm is fixed, for example, for a predetermined time from 5 seconds to 5 minutes, and the heat treatment apparatus shown in FIG. The substrate 10 (here, a silicon substrate) is rotated together with the support ring 5 using the above, and an oxidation treatment is performed between 500 and 1200 ° C. including the heat treatment temperature range used in the actual semiconductor device manufacturing process. At this time, in the heat treatment apparatus 1, the oxide film thickness d grown when the heat treatment temperature Tm is set is measured by changing the heat treatment temperature Tm in steps of 5 to 100 degrees. The oxide film thickness d can be measured with an ellipsometer or the like. Hereinafter, the heat treatment temperature set in the heat treatment apparatus is referred to as a heat treatment set temperature.

  FIG. 3 is a diagram showing the relationship between the heat treatment set temperature Tm and the oxide film thickness d obtained in this way. The temperature range for acquiring the temperature characteristic diagram is acquired from 500 ° C., which is the temperature measurement reliability of the temperature probe, to 1200 ° C., which is the maximum temperature range used in a general RTP process.

  FIG. 3 shows the heat treatment set temperature Tm of the oxide film thickness d at a position facing three temperature probes 7 (shown by solid lines, broken lines, and dotted lines in FIG. 3) arranged at different positions of the heat treatment apparatus of FIG. It is a figure which shows the example of dependence (calibration data). As shown in FIG. 3, even if the set temperature is the same, the oxide film thickness d formed at the position corresponding to each temperature probe 7 is different. This is because the temperature probe 7 does not measure the true temperature on the substrate 10, but during the heat treatment, the distance from the support ring 5 whose temperature is different from that of the substrate 10, the mounting condition of the temperature probe 7, and each temperature probe This is presumably because the apparent temperature was measured including variations such as the difference in the lamp power contribution to 7. Here, the calibration data as described above is acquired for all the temperature probes 7.

  After acquiring the calibration data shown in FIG. 3 for all temperature probes, a dry oxygen flow rate and a heat treatment maintenance time t are set as above using a dummy substrate (a silicon substrate may be used) with a silicon surface exposed. Then, dry oxidation is performed by a heat treatment sequence arbitrarily selected between a heat treatment set temperature Tm of 500 ° C. and 1200 ° C. And the temperature correction value of each temperature probe 7 is calculated | required based on the film thickness d of the oxide film formed by the said heat processing sequence.

  Here, the film thickness of the oxide film formed on the dummy substrate at a position facing each temperature probe 7 is measured. Then, based on the calibration data for each temperature probe 7 shown in FIG. 3, a heat treatment set temperature Tm corresponding to the oxide film thickness measured at each position is obtained. This temperature becomes the temperature T at the position where the oxide film is formed. For example, when an oxide film having a thickness of 10 nm is formed at a position facing the temperature probe 7 from which calibration data indicated by a solid line in FIG. 3 is acquired, the temperature T is 1050 ° C.

  Next, in the heat treatment of the dummy substrate, a difference between the heat treatment set temperature Tm ′ corresponding to the film thickness (target oxide film thickness) of the oxide film to be formed on the dummy substrate and the temperature T is obtained, and the temperature difference is calculated. The temperature correction value of the temperature probe 7 is used. For example, in the calibration data indicated by the solid line in FIG. 3, when the target oxide film thickness is 12 nm, the temperature Tm ′ is 1070 ° C. Therefore, the temperature difference ΔT is 20 ° C. That is, in order to obtain the target oxide film thickness at the position of the temperature probe 7, the lamp power of the heating lamp corresponding to the position may be adjusted as the temperature of the heat treatment set temperature Tm + ΔT.

  As described above, the temperature correction value of each temperature probe 7 is obtained, and the lamp film of the lamp unit is adjusted based on the temperature in consideration of the temperature correction value, so that the same oxide film is formed at any position on the substrate 10. The temperature can be adjusted to obtain a thickness. That is, the heat treatment temperature can be made substantially uniform in the plane of the substrate 10.

  In the above description, the temperature correction value of each temperature probe 7 is obtained based on the calibration data obtained in advance for each temperature probe 7. However, the temperature correction value can also be obtained as follows.

  FIG. 4 is a diagram showing calibration data showing the relationship between the oxide film thickness and the heat treatment set temperature Tm obtained in the same manner as FIG. Here, the oxide film thickness is different from that in FIG. 3 in that the average film thickness da in the plane of the substrate 10 is used. Thus, by using the average film thickness, the above-described temperature non-uniformity in the surface of the substrate 10 is eliminated. Further, in the range where the heat treatment set temperature Tm is 500 ° C. to 1200 ° C., the in-plane temperature non-uniformity is expected to be different, but the temperature variation width in the substrate surface is the same at any temperature. . Therefore, it can be considered that the calibration data shown in FIG. 4 using the in-plane average film thickness da is data in which the in-plane temperature variation is reduced.

  After obtaining the calibration data shown in FIG. 4, similarly to the above, using a dummy substrate, the dry oxygen flow rate and the heat treatment maintenance time t are fixed, and the heat treatment set temperature Tm is between 500 ° C. and 1200 ° C. Dry oxidation is performed by an arbitrarily selected heat treatment sequence. And the temperature correction value of each temperature probe 7 is calculated | required based on the film thickness d of the oxide film formed by the said heat processing sequence.

  Also in this case, the film thickness of the oxide film formed at the position facing each temperature probe 7 of the dummy substrate is measured, and the temperature T with respect to the oxide film thickness measured at each position is obtained from the calibration data of FIG. Next, a difference between the heat treatment set temperature Tm ′ and the temperature T corresponding to the target oxide film thickness obtained from the same curve of FIG. 4 is obtained, and the temperature difference is set as a temperature correction value of the temperature probe 7.

  For example, when an oxide film having a film thickness of 10 nm is formed at a position facing the temperature probe 7 to be calibrated, the temperature T is 1050 ° C. according to the calibration data shown in FIG. When the target oxide film thickness is 12 nm, the temperature Tm ′ is 1070 ° C. Therefore, the temperature difference ΔT is 20 ° C. That is, in order to obtain the target oxide film thickness at the position of the temperature probe 7, the lamp power of the heating lamp corresponding to the position may be adjusted as the temperature of the heat treatment set temperature Tm + ΔT.

  As described above, the temperature correction value of each temperature probe 7 is obtained, and the lamp film of the lamp unit is adjusted based on the temperature in consideration of the temperature correction value, so that the same oxide film is formed at any position on the substrate 10. The temperature can be adjusted to obtain a thickness. That is, the heat treatment temperature can be made substantially uniform in the plane of the substrate 10.

  However, in the calibration data of FIG. 4, the temperature correction value of each temperature probe 7 is acquired based on the average film thickness of the oxide film. In this case, the number of lamps to be heated at the position facing each temperature probe 7, the distance from the center of the substrate of each temperature probe, the cooling action of the outer periphery of the substrate by the support ring, the distance between each temperature probe, etc. It is not accurately reflected in the correction value. Therefore, in order to obtain a more accurate temperature correction value, it is preferable to perform further correction by adding a specific coefficient to the temperature correction value.

  As described above, the uniformity of the in-plane temperature of the substrate can be improved by using the method for adjusting the heat treatment temperature of the present invention. In particular, with the method of acquiring calibration data individually for each temperature probe 7, the temperature difference in the substrate surface can be suppressed to 4 degrees or less. Therefore, by performing the heat treatment of the substrate by the heat treatment apparatus in which the heat treatment temperature is adjusted by this method, it is possible to reduce the variation in characteristics and reliability of the semiconductor device in the substrate surface.

  FIG. 5 is a view showing a heat treatment apparatus provided with a temperature control means 20 for executing the above heat treatment temperature adjusting method. As shown in FIG. 5, in this heat treatment apparatus, the arithmetic processing unit 22 of the temperature control means 20 acquires the temperature of the substrate 10 measured by each temperature probe 7 (pyrometer is not shown). Then, the arithmetic processing unit 22 sends a control signal to the lamp driver 21 that individually controls the lamp power of a group of lamps provided in a region facing each temperature probe 7, with a temperature correction value for each temperature probe described above. Output. Note that the calibration data shown in FIG. 3 or FIG. 4 is set in the arithmetic processing unit 22. The lamp driver 21 and the arithmetic processing unit 22 include, for example, dedicated arithmetic circuits, hardware including a processor and a memory such as a RAM and a ROM, and software stored in the memory and operating on the processor. Can be realized.

  In the above configuration, when a heat treatment sequence including the heat treatment set temperature Tm is input from the input unit 23 by the operator, the arithmetic processing unit 22 performs the above calculation based on the calibration data set in advance. The temperature correction value of each temperature probe 7 is calculated. Then, the arithmetic processing unit 22 sends a control signal such that the temperature data input from each temperature probe 7 is corrected using each temperature correction value to the input heat treatment set temperatures Tm and Tm. Output to. The lamp driver 21 controls the lamp power of the lamp unit 2 according to the control signal.

  For this reason, according to the heat treatment apparatus having the above-described configuration, the lamp power is controlled based on the temperature correction value acquired by the above-described method, and therefore, the heat treatment can be performed with the entire surface of the substrate at a uniform temperature.

  In the above description, the temperature correction value is obtained at one heat treatment set temperature and the temperature adjustment is performed. However, once the adjustment is made, the non-uniformity is usually adjusted at other heat treatment temperatures. Heat treatment can be performed at other temperatures using the temperature correction value.

  By the way, according to the calibration data of FIGS. 3 and 4, it is possible to construct a function indicating the calibration data, Tm = f (d) (in the case of FIG. 3, there is a function for each temperature probe 7). Created). Therefore, the temperature correction value may be calculated by inputting the oxide film thickness measured with the dummy substrate from the input unit 23 by incorporating the function into the arithmetic processing unit 22. By obtaining such a function, it is possible to obtain a temperature correction value by extrapolation even in a temperature region outside the acquisition range of the calibration data. The arithmetic processing unit 22 may store the temperature correction value of each temperature probe 7 input from the input unit 23 and control the lamp driver 21 based on the temperature correction value.

  The present invention is not limited to the embodiments described above, and various modifications and applications are possible within the scope of the effects of the present invention. For example, the example in which the temperature correction value of each temperature probe is obtained based on the thickness of the dry oxide film on the dummy substrate has been described above. However, the oxide film may be an oxide film formed by wet oxidation. The temperature correction value is not limited to the oxide film thickness as long as it is a physical quantity that varies depending on the heat treatment, and can be obtained using any physical quantity. For example, heat treatment (activation annealing treatment) is performed using a semiconductor substrate into which impurities such as arsenic, phosphorus, and boron are ion-implanted, and the above-described distribution of the sheet resistance value of the impurity diffusion region after the heat treatment is used. It is also possible to obtain a temperature correction value. Since the sheet resistance value of such an impurity diffusion region reacts very sensitively to the heat treatment temperature, a stricter temperature correction value can be obtained.

  The present invention can improve the uniformity of the in-plane temperature of the substrate, and is useful for a heat treatment apparatus for performing heat treatment of a substrate.

The principal part longitudinal cross-sectional view of the heat processing apparatus of this invention The figure for demonstrating the heat processing sequence of this invention. The figure which shows an example of the calibration data of this invention The figure which shows an example of the calibration data of this invention Schematic configuration diagram of heat treatment apparatus of the present invention

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Heat processing apparatus 2 Lamp unit 3 Chamber 4 Quartz plate 5 Support ring 6 Rotating cylinder 7 Temperature probe 8 Gas introduction pipe 9 Gas outlet pipe 10 Substrate 20 Temperature control means 21 Lamp driver 22 Arithmetic processing part 23 Input part

Claims (9)

A method of adjusting a heat treatment temperature applied to a heat treatment apparatus for performing a temperature control based on temperatures measured at a plurality of positions on the same substrate and performing a heat treatment of the substrate,
Obtaining calibration data associating a physical quantity varying according to the heat treatment with a heat treatment set temperature;
Measuring the physical quantity at each temperature measurement position of the substrate heat-treated at a specific heat treatment set temperature;
A heat treatment set temperature corresponding to the measured physical quantity and a heat treatment set temperature corresponding to a physical quantity to be obtained at the specific heat treatment set temperature are acquired from the calibration data, and each physical quantity measurement position is based on these temperature differences. Obtaining a temperature correction value of the temperature probe corresponding to
A method for adjusting the heat treatment temperature, characterized by comprising:   The method for adjusting a heat treatment temperature according to claim 1, wherein the calibration data is data in which an average value of the physical quantities in a substrate surface is associated with a heat treatment set temperature.   The method for adjusting a heat treatment temperature according to claim 1, wherein the calibration data is acquired at each temperature measurement position.   The method for adjusting a heat treatment temperature according to claim 1, wherein the physical quantity is a thickness of an oxide film formed by the heat treatment.   The method for adjusting a heat treatment temperature according to claim 4, wherein the oxide film is a wet oxide film.   The method for adjusting a heat treatment temperature according to any one of claims 1 to 3, wherein the heat treatment is an activation annealing treatment of an impurity diffusion region formed on a substrate, and the physical quantity is a sheet resistance of the impurity diffusion region.   The method for adjusting a heat treatment temperature according to claim 6, wherein the impurity is arsenic, phosphorus, or boron.   A substrate heat treatment method for performing heat treatment of a substrate by a heat treatment apparatus adjusted by the heat treatment temperature adjustment method according to claim 1. In a heat treatment apparatus that performs temperature control based on temperatures measured at a plurality of positions on the same substrate and performs heat treatment of the substrate,
A plurality of heating means for heating the substrate;
A plurality of temperature probes for measuring the temperature of the substrate;
Means for correcting the temperature measured by each temperature probe based on the temperature correction value of each temperature probe calculated from the calibration data in which the physical quantity varying according to the heat treatment and the heat treatment set temperature are associated with each other;
Means for controlling the amount of heating of each heating means based on the corrected temperature;
A heat treatment apparatus comprising:

Images