JP6068556B2 - Heat treatment apparatus and heat treatment method - Google Patents

Description

  The present invention relates to a heat treatment apparatus and a heat treatment method for heating a substrate by irradiating light onto a semiconductor wafer, a glass substrate for a liquid crystal display device or the like (hereinafter simply referred to as “substrate”).

  In the semiconductor device manufacturing process, impurity introduction is an indispensable step for forming a pn junction in a semiconductor wafer. Currently, impurities are generally introduced by ion implantation and subsequent annealing. The ion implantation method is a technique in which impurity elements such as boron (B), arsenic (As), and phosphorus (P) are ionized and collided with a semiconductor wafer at a high acceleration voltage to physically perform impurity implantation. The implanted impurities are activated by annealing. At this time, if the annealing time is about several seconds or more, the implanted impurities are deeply diffused by heat, and as a result, the junction depth becomes deeper than required, and there is a possibility that good device formation may be hindered.

  Therefore, in recent years, flash lamp annealing (FLA) has attracted attention as an annealing technique for heating a semiconductor wafer in an extremely short time. Flash lamp annealing is a semiconductor wafer in which impurities are implanted by irradiating the surface of the semiconductor wafer with flash light using a xenon flash lamp (hereinafter, simply referred to as “flash lamp” means xenon flash lamp). This is a heat treatment technique that raises the temperature of only the surface of the material in a very short time (several milliseconds or less). The radiation spectral distribution of a xenon flash lamp ranges from the ultraviolet region to the near infrared region, has a shorter wavelength than the conventional halogen lamp, and almost coincides with the fundamental absorption band of a silicon semiconductor wafer. Therefore, when the semiconductor wafer is irradiated with flash light from the xenon flash lamp, the semiconductor wafer can be rapidly heated with little transmitted light. Further, it has been found that if the flash light is irradiated for a very short time of several milliseconds or less, only the vicinity of the surface of the semiconductor wafer can be selectively heated. For this reason, if the temperature is raised for a very short time by the xenon flash lamp, only the impurity activation can be performed without deeply diffusing the impurities.

  In Patent Document 1, in a flash lamp annealing apparatus, a calorimeter disposed outside the chamber body, a light derivation structure for guiding the light irradiated inside the chamber body to the calorimeter, and an output from the calorimeter There is disclosed a technique for providing a light measurement unit including a calculation unit that performs calculation based on the above, and measuring the energy of light irradiated from the flash lamp into the chamber body using a calorimeter.

JP 2005-93750 A

  The technique disclosed in Patent Document 1 is to measure the total energy of one flash light irradiation. The flash lamp emits light by discharging a charge charged to a capacitor with a predetermined voltage between the lamp electrodes. Therefore, the total energy of one flash light irradiation is generally determined by the capacitance of the capacitor and the charge voltage.

  However, the intensity of light emitted from the flash lamp even if the total energy is the same due to variations between flash lamps (for example, individual differences such as the distance between electrodes and the gas pressure enclosed) and deterioration of the flash lamp. The waveform could be different. It is also possible to intentionally change the intensity waveform of light emission by controlling energization to the flash lamp.

  On the other hand, the inventors of the present application irradiate the flash lamp when performing the activation process of the impurity and the recovery process of the crystal defect introduced at a position slightly deeper than the impurity implantation layer during the ion implantation by the flash lamp annealing. It was found that the intensity waveform of the light itself has a great influence on the processing result. That is, even if the total energy is the same, if the intensity waveform of the light emitted from the flash lamp is different, the processing results are also different.

  Therefore, in order to perform light irradiation heat treatment with good reproducibility, it is required to make not only the total energy but also the light intensity waveform the same, but the conventional technique as disclosed in Patent Document 1 is required. However, even the intensity waveform of the light emitted from the flash lamp could not be measured. In addition, the calorimeter used in the technique disclosed in Patent Document 1 converts the energy of light absorbed by the black body inside the sensor into an electrical signal, so the response speed is slow, and the flash lamp has a very short irradiation. It couldn't keep up with time.

  For this reason, even if the intensity waveform is abnormal in the light irradiated inside the chamber when processing the semiconductor wafer, it is extremely difficult to measure the intensity waveform of the irradiated light and detect the abnormality. It was.

  The present invention has been made in view of the above problems, and an object thereof is to provide a heat treatment apparatus and a heat treatment method capable of measuring an intensity waveform of light and detecting an abnormality in light irradiation from a flash lamp. .

  In order to solve the above-mentioned problems, a first aspect of the present invention is a heat treatment apparatus for heating a substrate by irradiating the substrate with light, and a chamber for accommodating the substrate and a holding for holding the substrate in the chamber. A flash lamp that irradiates light onto the substrate held by the holding unit, a switching element that controls a current flowing through the flash lamp, and a signal setting unit that sets a waveform of a signal applied to the gate of the switching element A signal generation unit that outputs a signal according to the waveform of the signal set by the signal setting unit and applies the signal to the gate of the switching element, and a time of intensity of light emitted from the flash lamp to the inside of the chamber A waveform measuring unit for measuring a waveform, and a signal having a predetermined waveform is applied to the gate of the switching element to A signal having the predetermined waveform is applied to the reference waveform, which is a time waveform of light intensity when normal light irradiation is performed, and the gate of the switching element, and the substrate to be processed is irradiated with light from the flash lamp. A waveform storage unit that stores a processing waveform that is a temporal waveform of light intensity when performed, and an abnormality detection unit that performs an abnormality detection process by comparing the reference waveform with the processing waveform, To do.

  According to a second aspect of the present invention, in the heat treatment apparatus according to the first aspect of the invention, the abnormality detection unit calculates a difference between the reference waveform and the processing waveform in a predetermined time range and performs abnormality detection processing. It is characterized by performing.

  According to a third aspect of the present invention, in the heat treatment apparatus according to the first aspect of the invention, the abnormality detection unit compares the integrated value of the reference waveform with the integrated value of the processing waveform in a predetermined time range. An abnormality detection process is performed.

  According to a fourth aspect of the present invention, in the heat treatment apparatus according to the first aspect of the invention, the abnormality detection unit performs an abnormality detection process by comparing the highest value of the reference waveform with the highest value of the processing waveform. It is characterized by.

  The invention according to claim 5 is the heat treatment apparatus according to claim 1, wherein the abnormality detection unit detects an abnormality by comparing the intensity value of the reference waveform and the intensity value of the processing waveform at a predetermined time. It is characterized by performing processing.

  The invention according to claim 6 is the heat treatment apparatus according to claim 1, wherein the abnormality detection unit includes the intensity value of the n-th peak (n is an integer of 1 or more) of the reference waveform and the processing waveform. An abnormality detection process is performed by comparing the intensity value with the n-th peak.

  The invention according to claim 7 is the heat treatment apparatus according to claim 1, wherein the abnormality detection unit includes a time of an n-th peak (n is an integer of 1 or more) of the reference waveform and an n of the processing waveform. The abnormality detection process is performed by comparing with the time of the first peak.

  The invention according to claim 8 is the heat treatment apparatus according to claim 2 or 3, wherein the abnormality detection unit sets the predetermined time range so as to include a peak of the reference waveform. And

  According to a ninth aspect of the present invention, in the heat treatment apparatus according to any one of the first to eighth aspects, the waveform measuring unit includes a photodiode.

  According to a tenth aspect of the present invention, in the heat treatment apparatus according to any one of the first to ninth aspects, the switching element is an insulated gate bipolar transistor.

  The invention according to claim 11 is the gate of the switching element for controlling the current flowing in the flash lamp in a heat treatment method for heating the substrate by irradiating light to the substrate held in the chamber from the flash lamp. A reference waveform acquisition step of acquiring a time waveform of the intensity of light irradiated inside the chamber as a reference waveform when a signal of a predetermined waveform is applied and normal light irradiation is performed from the flash lamp; Processing the time waveform of the intensity of the light applied to the inside of the chamber when the signal of the predetermined waveform is applied to the gate of the switching element and the substrate to be processed is irradiated with light from the flash lamp. A processing waveform acquisition step for acquiring a waveform, and an abnormality for performing an abnormality detection process by comparing the reference waveform and the processing waveform Characterized in that it comprises a left step.

  The invention according to claim 12 is the heat treatment method according to claim 11, wherein the abnormality detection step calculates the difference between the reference waveform and the processing waveform in a predetermined time range and performs abnormality detection processing. It is characterized by performing.

  The invention according to claim 13 is the heat treatment method according to claim 11, wherein the abnormality detecting step compares the integrated value of the reference waveform with the integrated value of the processing waveform in a predetermined time range. An abnormality detection process is performed.

  The invention according to claim 14 is the heat treatment method according to claim 11, wherein the abnormality detection step performs an abnormality detection process by comparing a maximum value of the reference waveform with a maximum value of the processing waveform. It is characterized by.

  The invention according to claim 15 is the heat treatment method according to claim 11, wherein the abnormality detection step detects an abnormality by comparing the intensity value of the reference waveform with the intensity value of the processing waveform at a predetermined time. It is characterized by performing processing.

  The invention according to claim 16 is the heat treatment method according to claim 11, wherein the abnormality detection step includes the intensity value of the n-th peak (n is an integer of 1 or more) of the reference waveform and the processing waveform. An abnormality detection process is performed by comparing the intensity value with the n-th peak.

  The invention according to claim 17 is the heat treatment method according to claim 11, wherein the abnormality detection step includes the time of the n-th peak (n is an integer of 1 or more) of the reference waveform and the n of the processing waveform. The abnormality detection process is performed by comparing with the time of the first peak.

  The invention according to claim 18 is the heat treatment method according to any one of claims 11 to 17, wherein the switching element is an insulated gate bipolar transistor.

  According to the first to tenth aspects of the present invention, light irradiation is performed on the substrate to be processed from the reference waveform that is the time waveform of the light intensity when normal light irradiation is performed from the flash lamp and the flash lamp. Since the abnormality detection process is performed by comparing with the processing waveform which is the time waveform of the light intensity at the time, the abnormality of the light irradiation from the flash lamp can be detected by measuring the light intensity waveform.

  In particular, according to the ninth aspect of the present invention, since the waveform measuring section includes the photodiode, even if the light irradiation time from the flash lamp is short, the light intensity waveform can be reliably measured and the light from the flash lamp can be measured. Irradiation abnormalities can be detected.

  According to the invention of claims 11 to 18, when the normal light irradiation from the flash lamp is performed, the reference waveform which is the time waveform of the intensity of the light irradiated into the chamber and the processing object from the flash lamp. In order to perform anomaly detection processing by comparing with the processing waveform that is the time waveform of the intensity of the light irradiated inside the chamber when the substrate is irradiated with light, the light intensity waveform is measured and the flash lamp It is possible to detect abnormalities in the light irradiation from.

It is a longitudinal cross-sectional view which shows the structure of the heat processing apparatus which concerns on this invention. It is sectional drawing which shows the gas path of the heat processing apparatus of FIG. It is sectional drawing which shows the structure of a holding | maintenance part. It is a top view which shows a hot plate. It is a longitudinal cross-sectional view which shows the structure of the heat processing apparatus of FIG. It is a figure which shows the drive circuit of a flash lamp. It is a block diagram which shows the structure of a waveform measurement part. It is a flowchart which shows the outline | summary of the whole processing procedure in the heat processing apparatus of FIG. It is a figure which shows the change of the surface temperature of the semiconductor wafer after preheating is started. It is a figure which shows an example of the waveform of a pulse signal. It is a figure which shows an example of the waveform of the emitted light intensity of a flash lamp. It is a figure which shows the other example of the waveform of the emitted light intensity of a flash lamp. It is a figure which shows the other example of the waveform of the emitted light intensity of a flash lamp. It is a figure which shows the other example of the waveform of the emitted light intensity of a flash lamp. It is a flowchart which shows the waveform acquisition procedure of the light irradiated inside a chamber. It is a figure for demonstrating an example of the comparison with a reference | standard waveform and a process waveform. It is a figure for demonstrating the other example of a comparison with a reference | standard waveform and a process waveform. It is a figure for demonstrating the other example of a comparison with a reference | standard waveform and a process waveform. It is a figure for demonstrating the other example of a comparison with a reference | standard waveform and a process waveform. It is a figure for demonstrating the other example of a comparison with a reference | standard waveform and a process waveform. It is a longitudinal cross-sectional view which shows the other example of a structure of the heat processing apparatus. It is a longitudinal cross-sectional view which shows the other example of a structure of the heat processing apparatus. It is a longitudinal cross-sectional view which shows the other example of a structure of the heat processing apparatus.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

<1. Configuration of heat treatment equipment>
<1-1. Overall schematic configuration>
First, the overall schematic configuration of the heat treatment apparatus according to the present invention will be described. FIG. 1 is a longitudinal sectional view showing a configuration of a heat treatment apparatus 1 according to the present invention. The heat treatment apparatus 1 is a lamp annealing apparatus that irradiates a substantially circular semiconductor wafer W as a substrate with light and heats the semiconductor wafer W.

  The heat treatment apparatus 1 includes a substantially cylindrical chamber 6 that accommodates a semiconductor wafer W, and a lamp house 5 that houses a plurality of flash lamps FL. In addition, the heat treatment apparatus 1 includes a main controller 3 that controls each operation mechanism provided in the chamber 6 and the lamp house 5 to execute the heat treatment of the semiconductor wafer W.

  The chamber 6 is provided below the lamp house 5 and includes a chamber side 63 having a substantially cylindrical inner wall and a chamber bottom 62 covering the lower part of the chamber side 63. A space surrounded by the chamber side 63 and the chamber bottom 62 is defined as a heat treatment space 65. An upper opening 60 is formed above the heat treatment space 65, and a chamber window 61 is attached to the upper opening 60 to be closed.

  The chamber window 61 constituting the ceiling portion of the chamber 6 is a disk-shaped member made of quartz, and transmits light emitted from the lamp house 5 to the heat treatment space 65. The chamber bottom 62 and the chamber side 63 constituting the main body of the chamber 6 are formed of, for example, a metal material having excellent strength and heat resistance such as stainless steel, and a ring on the upper side of the inner side surface of the chamber side 63. 631 is formed of an aluminum (Al) alloy or the like having durability superior to stainless steel against deterioration due to light irradiation.

  Further, in order to maintain the airtightness of the heat treatment space 65, the chamber window 61 and the chamber side portion 63 are sealed by an O-ring. That is, the O-ring is sandwiched between the lower surface peripheral portion of the chamber window 61 and the chamber side portion 63, the clamp ring 90 is brought into contact with the upper peripheral portion of the chamber window 61, and the clamp ring 90 is attached to the chamber side portion 63. The chamber window 61 is pressed against the O-ring by screwing.

  The chamber bottom 62 has a plurality (in this embodiment) for supporting the semiconductor wafer W from the lower surface (surface opposite to the side irradiated with light from the lamp house 5) through the holding portion 7. 3) support pins 70 are provided upright. The support pin 70 is made of, for example, quartz and is fixed from the outside of the chamber 6 and can be easily replaced.

The chamber side 63 has a transfer opening 66 for carrying in and out the semiconductor wafer W, and the transfer opening 66 can be opened and closed by a gate valve 185 that rotates about a shaft 662. In a portion of the chamber side 63 opposite to the transfer opening 66, an inert gas such as a processing gas (for example, nitrogen (N ₂ ) gas, helium (He) gas, argon (Ar) gas), etc. Alternatively, an introduction path 81 for introducing oxygen (O ₂ ) gas or the like is formed, one end of which is connected to an air supply mechanism (not shown) via a valve 82, and the other end is formed inside the chamber side portion 63. Connected to the gas introduction buffer 83. A discharge passage 86 for discharging the gas in the heat treatment space 65 is formed in the transfer opening 66 and is connected to an exhaust mechanism (not shown) through a valve 87.

  FIG. 2 is a cross-sectional view of the chamber 6 cut along a horizontal plane at the position of the gas introduction buffer 83. As shown in FIG. 2, the gas introduction buffer 83 is formed over about ３ of the inner periphery of the chamber side 63 on the opposite side of the transfer opening 66 shown in FIG. Then, the processing gas guided to the gas introduction buffer 83 is supplied into the heat treatment space 65 from the plurality of gas supply holes 84.

  The heat treatment apparatus 1 also includes a substantially disk-shaped holding unit 7 that holds the semiconductor wafer W in a horizontal position in the chamber 6 and performs preheating of the semiconductor wafer W held before light irradiation, and a holding unit. And a holding unit elevating mechanism 4 that elevates 7 with respect to the chamber bottom 62 which is the bottom surface of the chamber 6. 1 includes a substantially cylindrical shaft 41, a moving plate 42, guide members 43 (three arranged around the shaft 41 in the present embodiment), a fixed plate 44, a ball screw 45, It has a nut 46 and a motor 40. A substantially circular lower opening 64 having a smaller diameter than the holding portion 7 is formed in the chamber bottom 62 which is the lower portion of the chamber 6, and the stainless steel shaft 41 is inserted through the lower opening 64 to hold the holding portion. 7 (strictly speaking, the hot plate 71 of the holding unit 7) is connected to the lower surface of the holding unit 7 to support it.

  A nut 46 that is screwed into the ball screw 45 is fixed to the moving plate 42. The moving plate 42 is slidably guided by a guide member 43 that is fixed to the chamber bottom 62 and extends downward, and is movable in the vertical direction. Further, the moving plate 42 is connected to the holding unit 7 via the shaft 41.

  The motor 40 is installed on a fixed plate 44 attached to the lower end of the guide member 43, and is connected to the ball screw 45 via the timing belt 401. When the holding part 7 is raised and lowered by the holding part raising / lowering mechanism 4, the motor 40 as a driving part rotates the ball screw 45 under the control of the main controller 3, and the moving plate 42 to which the nut 46 is fixed follows the guide member 43. Move vertically. As a result, the shaft 41 fixed to the moving plate 42 moves along the vertical direction, and the holding unit 7 connected to the shaft 41 moves between the delivery position of the semiconductor wafer W shown in FIG. 1 and the semiconductor wafer W shown in FIG. Move up and down smoothly between the processing positions.

  On the upper surface of the moving plate 42, a mechanical stopper 451 having a substantially semi-cylindrical shape (a shape obtained by cutting the cylinder in half along the longitudinal direction) is provided so as to extend along the ball screw 45. If the upper limit of the mechanical stopper 451 is struck against the end plate 452 provided at the end of the ball screw 45, the moving plate 42 is prevented from rising abnormally. Thereby, the holding part 7 does not rise above a predetermined position below the chamber window 61, and the collision between the holding part 7 and the chamber window 61 is prevented.

  The holding unit lifting mechanism 4 has a manual lifting unit 49 that manually lifts and lowers the holding unit 7 when performing maintenance inside the chamber 6. The manual elevating unit 49 has a handle 491 and a rotating shaft 492. By rotating the rotating shaft 492 through the handle 491, the ball screw 45 connected to the rotating shaft 492 is rotated through the timing belt 495 to hold the holding unit. 7 can be moved up and down.

  A telescopic bellows 47 that surrounds the shaft 41 and extends downward is provided below the chamber bottom 62, and its upper end is connected to the lower surface of the chamber bottom 62. On the other hand, the lower end of the bellows 47 is attached to the bellows lower end plate 471. The bellows lower end plate 471 is attached by being screwed to the shaft 41 by a flange-shaped member 411. The bellows 47 is contracted when the holding portion 7 is raised with respect to the chamber bottom 62 by the holding portion lifting mechanism 4, and the bellows 47 is expanded when the holding portion 7 is lowered. When the holding unit 7 moves up and down, the airtight state in the heat treatment space 65 is maintained by the expansion and contraction of the bellows 47.

  FIG. 3 is a cross-sectional view showing the configuration of the holding unit 7. The holding unit 7 is installed on a hot plate (heating plate) 71 that preheats the semiconductor wafer W (so-called assist heating), and an upper surface of the hot plate 71 (a surface on the side where the holding unit 7 holds the semiconductor wafer W). The susceptor 72 is provided. As described above, the shaft 41 that moves up and down the holding unit 7 is connected to the lower surface of the holding unit 7. The susceptor 72 is made of quartz (or may be aluminum nitride (AIN) or the like), and a pin 75 for preventing displacement of the semiconductor wafer W is provided on the upper surface thereof. The susceptor 72 is installed on the hot plate 71 with its lower surface in surface contact with the upper surface of the hot plate 71. Thus, the susceptor 72 diffuses the thermal energy from the hot plate 71 and transmits it to the semiconductor wafer W placed on the upper surface of the susceptor 72, and can be removed from the hot plate 71 and cleaned during maintenance.

  The hot plate 71 includes an upper plate 73 and a lower plate 74 made of stainless steel. A resistance heating wire 76 such as a nichrome wire for heating the hot plate 71 is disposed between the upper plate 73 and the lower plate 74, and is filled with a conductive nickel (Ni) solder and sealed. The end portions of the upper plate 73 and the lower plate 74 are bonded by brazing.

  FIG. 4 is a plan view showing the hot plate 71. As shown in FIG. 4, the hot plate 71 includes a disc-shaped zone 711 and an annular zone 712 that are concentrically arranged in a central portion of a region facing the held semiconductor wafer W, and a zone 712. There are four zones 713 to 716 obtained by equally dividing a peripheral substantially annular region into four equal parts in the circumferential direction, and a slight gap is formed between the zones. The hot plate 71 is provided with three through holes 77 through which the support pins 70 are inserted, every 120 ° on the circumference of the gap between the zone 711 and the zone 712.

  In each of the six zones 711 to 716, heaters are individually formed so that mutually independent resistance heating wires 76 circulate, and each zone is individually formed by a heater built in each zone. Heated. The semiconductor wafer W held by the holding unit 7 is heated by heaters built in the six zones 711 to 716. Each of the zones 711 to 716 is provided with a sensor 710 that measures the temperature of each zone using a thermocouple. Each sensor 710 passes through the inside of a substantially cylindrical shaft 41 and is connected to the main controller 3.

  When the hot plate 71 is heated, the resistance heating wire disposed in each zone is set so that the temperature of each of the six zones 711 to 716 measured by the sensor 710 becomes a predetermined temperature. The amount of power supplied to 76 is controlled by the main controller 3. The temperature control of each zone by the main controller 3 is performed by PID (Proportional, Integral, Derivative) control. In the hot plate 71, the temperature of each of the zones 711 to 716 is continuously measured until the heat treatment of the semiconductor wafer W (when plural semiconductor wafers W are continuously processed, the heat treatment of all the semiconductor wafers W) is completed. Then, the power supply amount to the resistance heating wire 76 disposed in each zone is individually controlled, that is, the temperature of the heater built in each zone is individually controlled, and the temperature of each zone becomes the set temperature. Maintained. The set temperature of each zone can be changed by an offset value set individually from the reference temperature.

  The resistance heating wires 76 respectively disposed in the six zones 711 to 716 are connected to a power supply source (not shown) via a power line passing through the inside of the shaft 41. On the way from the power supply source to each zone, the power lines from the power supply source are arranged so as to be electrically insulated from each other inside a stainless tube filled with an insulator such as magnesia (magnesium oxide). The The interior of the shaft 41 is open to the atmosphere.

  Next, the lamp house 5 is provided above the holding part 7 in the chamber 6. The lamp house 5 includes a light source including a plurality of (30 in the present embodiment) xenon flash lamps FL and a reflector 52 provided so as to cover the light source inside the housing 51. Composed. A lamp light emission window 53 is attached to the bottom of the casing 51 of the lamp house 5. The lamp light radiation window 53 constituting the floor of the lamp house 5 is a plate-like member made of quartz. By installing the lamp house 5 above the chamber 6, the lamp light emission window 53 faces the chamber window 61. The lamp house 5 heats the semiconductor wafer W by irradiating the semiconductor wafer W held by the holding unit 7 in the chamber 6 with light from the flash lamp FL through the lamp light emission window 53 and the chamber window 61.

  Each of the plurality of flash lamps FL is a rod-shaped lamp having a long cylindrical shape, and the longitudinal direction of each of the flash lamps FL is along the main surface of the semiconductor wafer W held by the holding unit 7 (that is, along the horizontal direction). They are arranged in a plane so as to be parallel to each other. Therefore, the plane formed by the arrangement of the flash lamps FL is also a horizontal plane.

  In addition, the reflector 52 is provided above the plurality of flash lamps FL so as to cover all of them. The basic function of the reflector 52 is to reflect the light emitted from the plurality of flash lamps FL toward the holding unit 7. The reflector 52 is formed of an aluminum alloy plate, and the surface (the surface facing the flash lamp FL) is roughened by blasting to exhibit a satin pattern. The roughening process is performed when the surface of the reflector 52 is a perfect mirror surface, and a regular pattern is generated in the intensity of the reflected light from the plurality of flash lamps FL, so that the surface temperature distribution of the semiconductor wafer W is obtained. This is because the uniformity of the is reduced.

  The main controller 3 also controls the various operating mechanisms provided in the heat treatment apparatus 1. The configuration of the main controller 3 as hardware is the same as that of a general computer. That is, the main controller 3 stores a CPU that performs various arithmetic processes, a ROM that is a read-only memory that stores basic programs, a RAM that is a readable and writable memory that stores various information, control software, data, and the like. It has a magnetic disk.

  In addition to the above configuration, the heat treatment apparatus 1 is used for various cooling purposes in order to prevent excessive temperature rise of the chamber 6 and the lamp house 5 due to the heat energy generated from the flash lamp FL and the hot plate 71 during the heat treatment of the semiconductor wafer W. It has the structure of For example, water-cooled tubes (not shown) are provided on the chamber side 63 and the chamber bottom 62 of the chamber 6. The lamp house 5 has an air cooling structure provided with a gas supply pipe 55 and an exhaust pipe 56 for exhausting heat by forming a gas flow therein (see FIG. 1). Air is also supplied to the gap between the chamber window 61 and the lamp light emission window 53 to cool the lamp house 5 and the chamber window 61.

<1-2. Lamp drive circuit>
FIG. 6 is a diagram showing a driving circuit for the flash lamp FL. As shown in the figure, a capacitor 93, a coil 94, a flash lamp FL, and a switching element 96 are connected in series. As shown in FIG. 6, the main controller 3 includes a pulse generator 31 and a pulse setting unit 32 and is connected to the input unit 33. As the input unit 33, various known input devices such as a keyboard, a mouse, and a touch panel can be employed. The pulse setting unit 32 sets the waveform of the pulse signal based on the input content from the input unit 33, and the pulse generator 31 generates the pulse signal according to the waveform.

  The flash lamp FL includes a rod-shaped glass tube (discharge tube) 92 in which xenon gas is sealed and an anode and a cathode are disposed at both ends thereof, and a trigger electrode provided on the outer peripheral surface of the glass tube 92. 91. A predetermined voltage is applied to the capacitor 93 by the power supply unit 95, and a charge corresponding to the applied voltage is charged. A voltage can be applied from the trigger circuit 97 to the trigger electrode 91. The timing at which the trigger circuit 97 applies a voltage to the trigger electrode 91 is controlled by the main controller 3.

  In the present embodiment, an insulated gate bipolar transistor (IGBT) is used as the switching element 96. The IGBT is a bipolar transistor in which a MOSFET (Metal Oxide Semiconductor Field Effect Transistor) is incorporated in a gate portion, and is a switching element suitable for handling high power. A pulse signal is applied from the pulse generator 31 of the main controller 3 to the gate of the switching element 96.

  Even when a pulse is output to the gate of the switching element 96 with the capacitor 93 charged and a high voltage is applied to both ends of the glass tube 92, the xenon gas is normally an insulator, so In this state, electricity does not flow in the glass tube 92. However, when the trigger circuit 97 applies a voltage to the trigger electrode 91 to break the insulation, an electric current instantaneously flows in the glass tube 92 due to the discharge between the two end electrodes, and the excitation of the xenon atoms or molecules at that time Light is emitted.

<1-3. Waveform measurement mechanism>
As shown in FIGS. 1 and 5, the heat treatment apparatus 1 of this embodiment includes a quartz probe 18 and a waveform measuring unit 20. The quartz probe 18 is a light guide rod made of quartz and is erected on the chamber bottom 62. As shown in FIG. 5, the height position of the tip of the quartz probe 18 is preferably the same as the height position of the semiconductor wafer W held at the processing position. The base end of the quartz probe 18 passes through the chamber bottom 62 and faces the outside of the chamber 6.

  The base end of the quartz probe 18 is connected to the waveform measuring unit 20 via the optical fiber 17. FIG. 7 is a block diagram showing a configuration of the waveform measuring unit 20. The waveform measurement unit 20 includes a photodiode 21, a current / voltage conversion circuit 22, an amplification circuit 23, a high-speed A / D converter 24, and a one-chip microcomputer 25. The photodiode 21 generates a photocurrent according to the intensity of light received by the photovoltaic effect. The photodiode 21 has a characteristic that the response time is extremely short. Although the wavelength range of light detected by the photodiode 21 varies depending on the material used, the silicon photodiode 21 can detect infrared light from visible light, and can detect light from the flash lamp FL. Is preferred. The current-voltage conversion circuit 22 is a circuit that converts a weak current generated in the photodiode 21 into a voltage signal that can be easily handled. The current-voltage conversion circuit 22 can be configured using, for example, an operational amplifier.

  The amplification circuit 23 amplifies the voltage signal output from the current-voltage conversion circuit 22 and outputs the amplified voltage signal to the high-speed A / D converter 24. The high-speed A / D converter 24 converts the voltage signal amplified by the amplifier circuit 23 into a digital signal. The one-chip microcomputer 25 is a kind of microcomputer and is a processing device in which a CPU, a memory, a timer, and the like are mounted on one IC chip. The one-chip microcomputer 25 cannot perform general-purpose processing, but can perform specific processing at high speed. The one-chip microcomputer 25 of this embodiment samples the digital signal output from the high-speed A / D converter 24 at a predetermined interval and sequentially stores it in a memory in the chip. The sampling interval of the one-chip microcomputer 25 can be set as appropriate, but can be as short as 2 microseconds (μ seconds).

  The one-chip microcomputer 25 of the waveform measuring unit 20 is connected to the main controller 3 via a communication line. As described above, the main controller 3 has the same configuration as a general computer. Normally, the main controller 3 can perform general-purpose processing, but cannot perform sampling at intervals as short as the one-chip microcomputer 25. The digital data stored in the on-chip memory by the one-chip microcomputer 25 is transferred to the main controller 3 and stored in the waveform storage unit 35. The waveform storage unit 35 is configured by a storage medium such as a memory of the main controller 3 or a magnetic disk. The main controller 3 includes an abnormality detection unit 37. The abnormality detection unit 37 is a processing unit that is realized by the CPU of the main controller 3 executing predetermined processing software, and details of the processing will be described later. The communication line connecting the one-chip microcomputer 25 and the main controller 3 may be serial communication or parallel communication.

<2. Operation of heat treatment equipment>
<2-1. Overview of overall processing procedure in heat treatment equipment>
Next, operation | movement of the heat processing apparatus 1 which has said structure is demonstrated. FIG. 8 is a flowchart showing an outline of the entire processing procedure in the heat treatment apparatus 1.

  First, prior to processing of the semiconductor wafer W to be processed, when normal light irradiation is performed from the flash lamp FL of the lamp house 5, a time waveform (time waveform) of the intensity of light irradiated into the chamber 6 is set. Profile) is acquired as a reference waveform (step S1). That is, the “reference waveform” is an intensity waveform of light inside the chamber 6 when normal light irradiation is performed from the flash lamp FL, and is an intensity waveform that serves as a reference in the abnormality detection process in step S6. The reference waveform may be acquired by irradiating light from the flash lamp FL when a dummy wafer or the like exists in the chamber 6 or by irradiating light from the flash lamp FL when no wafer exists. You may do it. The reference waveform acquired in step S1 is finally stored in the waveform storage unit 35 of the main controller 3 (step S2). The acquisition of the waveform of the light irradiated into the chamber 6 will be further described later.

  Next, a light irradiation heat treatment is performed on the semiconductor wafer W to be processed (step S3). Here, the semiconductor wafer W to be processed is a semiconductor substrate into which impurities (ions) have been implanted by an ion implantation method, and activation of the implanted impurities is performed by light irradiation heat treatment (annealing) by the heat treatment apparatus 1. . Further, when performing the light irradiation heat treatment of the semiconductor wafer W, a time waveform of the intensity of the light irradiated into the chamber 6 is acquired as a processing waveform (step S4). That is, the “processing waveform” is a light intensity waveform inside the chamber 6 when the semiconductor wafer W actually to be processed is irradiated from the flash lamp FL, and is compared in the abnormality detection processing in step S6. It is a target intensity waveform. Step S4 is performed in a part of the process in which the light irradiation heat treatment of step S3 is performed. The processing waveform acquired in step S4 is finally stored in the waveform storage unit 35 of the main controller 3 (step S5). In the present specification, the simple term “intensity waveform” means an intensity time waveform.

  Next, processing abnormality detection processing is executed based on the acquired reference waveform and processing waveform (step S6). The process abnormality detection process in step S6 will be further described later. Then, after the abnormality detection process is completed, it is determined whether or not the processes for all the semiconductor wafers W constituting the lot have been completed (step S7). If the processing of all the semiconductor wafers W has not been completed, the process returns to step S3, and the light irradiation heat treatment of the new semiconductor wafer W and the light intensity waveform acquisition at that time are executed. In this way, the processes in steps S3 to S6 are repeated for all the semiconductor wafers W to be processed.

<2-2. Light irradiation heat treatment of semiconductor wafers>
Next, the light irradiation heat treatment in step S3 of FIG. 8 will be described. First, the holding unit 7 is lowered from the processing position shown in FIG. 5 to the delivery position shown in FIG. The “processing position” is the position of the holding unit 7 when the semiconductor wafer W is irradiated with light from the flash lamp FL, and is the position in the chamber 6 of the holding unit 7 shown in FIG. Further, the “delivery position” is the position of the holding unit 7 when the semiconductor wafer W is carried in and out of the chamber 6, and is the position of the holding unit 7 shown in FIG. The reference position of the holding unit 7 in the heat treatment apparatus 1 is the processing position. Before the processing, the holding unit 7 is located at the processing position, and this is lowered to the delivery position at the start of processing. As shown in FIG. 1, when the holding portion 7 is lowered to the delivery position, the holding portion 7 comes close to the chamber bottom portion 62, and the tip of the support pin 70 penetrates the holding portion 7 and protrudes above the holding portion 7.

  Next, when the holding unit 7 is lowered to the delivery position, the valve 82 and the valve 87 are opened, and normal temperature nitrogen gas is introduced into the heat treatment space 65 of the chamber 6. Subsequently, the gate valve 185 is opened to open the transfer opening 66, and the semiconductor wafer W is loaded into the chamber 6 through the transfer opening 66 by the transfer robot outside the apparatus and placed on the plurality of support pins 70. Is done.

  The purge amount of nitrogen gas into the chamber 6 when the semiconductor wafer W is loaded is about 40 liters / minute, and the supplied nitrogen gas is moved from the gas introduction buffer 83 in the direction of the arrow AR4 shown in FIG. Then, the exhaust gas is exhausted by utility exhaust via the discharge path 86 and the valve 87 shown in FIG. A part of the nitrogen gas supplied to the chamber 6 is also discharged from an outlet (not shown) provided inside the bellows 47. In each step described below, nitrogen gas is continuously supplied to and exhausted from the chamber 6, and the supply amount of the nitrogen gas is variously changed according to the processing process of the semiconductor wafer W.

  When the semiconductor wafer W is loaded into the chamber 6, the transfer opening 66 is closed by the gate valve 185. The holding unit lifting mechanism 4 raises the holding unit 7 from the delivery position to a processing position close to the chamber window 61. In the process in which the holding unit 7 is lifted from the delivery position, the semiconductor wafer W is transferred from the support pins 70 to the susceptor 72 of the holding unit 7 and is placed and held on the upper surface of the susceptor 72. When the holding unit 7 is raised to the processing position, the semiconductor wafer W held by the susceptor 72 is also held at the processing position.

  Each of the six zones 711 to 716 of the hot plate 71 is heated to a predetermined temperature by a heater (resistive heating wire 76) individually incorporated in each zone (between the upper plate 73 and the lower plate 74). ing. When the holding unit 7 rises to the processing position and the semiconductor wafer W comes into contact with the holding unit 7, the semiconductor wafer W is preheated by the heater built in the hot plate 71 and the temperature gradually rises.

  FIG. 9 is a diagram showing a change in the surface temperature of the semiconductor wafer W since the preheating is started. Preheating is performed for a time tp at the processing position, and the temperature of the semiconductor wafer W rises to a preset preheating temperature T1. The preheating temperature T1 is set to about 200 ° C. to 800 ° C., preferably about 350 ° C. to 600 ° C. (in this embodiment, 600 ° C.) at which impurities added to the semiconductor wafer W are not likely to diffuse due to heat. . The time tp for preheating the semiconductor wafer W is about 3 seconds to 200 seconds (60 seconds in the present embodiment). The distance between the holding unit 7 and the chamber window 61 can be arbitrarily adjusted by controlling the rotation amount of the motor 40 of the holding unit lifting mechanism 4.

  After the preheating time of time tp has elapsed, light irradiation heating of the semiconductor wafer W by the flash lamp FL is started at time A. When irradiating light from the flash lamp FL, charges are accumulated in the capacitor 93 by the power supply unit 95 in advance. Then, a pulse signal is output from the pulse generator 31 of the main controller 3 to the switching element 96 in a state where charges are accumulated in the capacitor 93.

  FIG. 10 is a diagram illustrating an example of a waveform of a pulse signal. The waveform of the pulse signal can be defined by inputting from the input unit 33 a recipe in which a pulse width time (on time) and a pulse interval time (off time) are sequentially set. When the operator inputs such a recipe from the input unit 33 to the main controller 3, the pulse setting unit 32 of the main controller 3 sets a pulse waveform that repeats ON / OFF as shown in FIG. Then, the pulse generator 31 outputs a pulse signal according to the pulse waveform set by the pulse setting unit 32. As a result, a pulse signal having a waveform as shown in FIG. 10 is applied to the gate of the switching element 96, and the on / off driving of the switching element 96 is controlled.

  The main controller 3 controls the trigger circuit 97 to apply a voltage to the trigger electrode 91 in synchronization with the timing when the pulse signal output from the pulse generator 31 is turned on. Thus, when the pulse signal input to the gate of the switching element 96 is on, a current always flows between the two end electrodes in the glass tube 92, and light is emitted by excitation of the xenon atoms or molecules at that time. A pulse signal having the waveform of FIG. 10 is output from the main controller 3 to the gate of the switching element 96, and a voltage is applied to the trigger electrode 91 in synchronization with the timing when the pulse signal is turned on, thereby including the flash lamp FL. A sawtooth current flows in the circuit. That is, the value of the current flowing in the glass tube 92 of the flash lamp FL increases when the pulse signal input to the gate of the switching element 96 is on, and the current value decreases when the pulse signal is off. Each current waveform corresponding to each pulse is defined by a constant of the coil 94.

  When a current flows through a circuit including the flash lamp FL, the flash lamp FL emits light. The emission intensity of the flash lamp FL is substantially proportional to the current flowing through the flash lamp FL. As a result, the time waveform (time profile) of the light emission intensity of the flash lamp FL has a pattern as shown in FIG. With the intensity waveform from the flash lamp FL as shown in FIG. 11, the semiconductor wafer W held on the processing position holding unit 7 is irradiated with light.

  Here, when the flash lamp FL is caused to emit light without using the switching element 96, the electric charge accumulated in the capacitor 93 is instantaneously consumed by one light emission. For this reason, the waveform of the light emission intensity of the flash lamp FL is a single pulse with a width that suddenly rises and drops sharply about 0.1 to 10 milliseconds.

  On the other hand, as in the present embodiment, the switching element 96 is connected in the circuit and the pulse signal as shown in FIG. 10 is output to the gate thereof, so that the emission of the flash lamp FL is chopper-controlled. As a result, the electric charge accumulated in the capacitor 93 is divided and consumed, and the flash lamp FL repeatedly blinks in a very short time. However, before the current value flowing through the flash lamp FL becomes completely “0”, the next pulse is applied to the gate of the switching element 96 to increase the current value again. Therefore, the light emission intensity does not completely become “0” even while the flash lamp FL is repeatedly blinking, and the light emission intensity of the flash lamp FL is as shown in FIG. Draw a pattern.

  If not only the activation of the impurities implanted into the semiconductor wafer W but also the recovery of crystal defects introduced at a position slightly deeper than the impurity implantation layer at the time of ion implantation, the intensity waveform of a simple single pulse is used. For example, an intensity waveform as shown in FIG. 11 having a plurality of peaks may be preferable. Also, from the viewpoint of preventing the semiconductor wafer W from cracking due to a rapid temperature change, an intensity waveform having a plurality of peaks as shown in FIG. 11 may be preferable to a simple single pulse intensity waveform.

  Further, by adjusting the waveform of the pulse signal applied to the gate of the switching element 96, the time waveform of the light emission intensity of the flash lamp FL can be changed to a pattern as shown in FIGS. The waveform of the pulse signal can be adjusted by the time of the pulse width and the time of the pulse interval input from the input unit 33.

  In the time waveform of the emission intensity shown in FIG. 12, the flash lamp FL first emits light with a waveform having a peak, and then emits light with a gentle waveform for a relatively long time at an emission intensity lower than the intensity value of the peak. Is. Conversely, the time waveform of the emission intensity shown in FIG. 14 is such that the flash lamp FL first emits light with a gentle waveform for a relatively long time, and then emits light with a waveform having a peak at the end. 13 is a flat waveform in which the flash lamp FL emits light with a substantially constant intensity for a relatively long time. Thus, by adjusting the waveform of the pulse signal applied to the gate of the switching element 96, the time waveform of the light emission intensity of the flash lamp FL can be freely changed. However, regardless of the form of the time waveform of the light emission intensity of the flash lamp FL, the light emission time of the flash lamp FL in one heat treatment is 1 second or less.

  By performing light irradiation from the flash lamp FL with an intensity waveform as shown in FIGS. 11 to 14, the surface temperature of the semiconductor wafer W is gradually raised from the preheating temperature T1 to the target processing temperature T2. Decrease the temperature slowly. However, even if the surface temperature of the semiconductor wafer W gradually rises and then falls slowly, it is just compared to conventional flash lamp annealing, and the flash lamp FL emission time is less than 1 second. Therefore, compared with light irradiation heating using a halogen lamp or the like, the temperature rises and falls in a remarkably short time.

  After the light irradiation heating by the flash lamp FL is completed, the semiconductor wafer W waits for about 10 seconds at the processing position, and then the holding unit 7 is lowered again to the delivery position shown in FIG. Is passed from the holding portion 7 to the support pin 70. Subsequently, the transfer opening 66 closed by the gate valve 185 is opened, and the semiconductor wafer W placed on the support pins 70 is unloaded by the transfer robot outside the apparatus, and the light of the semiconductor wafer W in the heat treatment apparatus 1 is transferred. Irradiation heat treatment is completed.

  As described above, nitrogen gas is continuously supplied to the chamber 6 during the heat treatment of the semiconductor wafer W in the heat treatment apparatus 1, and the supply amount is about 30 liters / minute when the holding unit 7 is located at the processing position. When the holding unit 7 is located at a position other than the processing position, the rate is about 40 liters / minute.

<2-3. Waveform measurement processing of light incident on the chamber>
Next, the acquisition of the reference waveform in step S1 in FIG. 8 and the acquisition of the processing waveform in step S4 will be described. The waveform acquisition in step S1 and step S4 is both performed by the quartz probe 18 and the waveform measurement unit 20, and the processing content itself in both steps is the same.

  FIG. 15 is a flowchart showing a procedure for acquiring the waveform of the light applied to the inside of the chamber 6. The waveform acquisition processing procedure shown in FIG. 15 proceeds as the one-chip microcomputer 25 executes each step. First, it is determined whether or not the input voltage from the high-speed A / D converter 24 to the one-chip microcomputer 25 is equal to or higher than a predetermined threshold (step S11). Even when light is not irradiated inside the chamber 6, the photodiode 21 generates a very weak current, and prevents a voltage signal resulting from such current from being acquired as light intensity data. Therefore, the determination process of step S11 is performed. The predetermined threshold value in step S11, that is, the recording start voltage can be set to an appropriate value according to the circuit characteristics of the waveform measuring unit 20 (in this embodiment, 1 V).

  While the input voltage from the high-speed A / D converter 24 to the one-chip microcomputer 25 continues to be less than a predetermined threshold, the one-chip microcomputer 25 is on standby. On the other hand, when the input voltage becomes equal to or higher than a predetermined threshold value, the one-chip microcomputer 25 starts measuring time with a timer (step S12).

  The input voltage from the high-speed A / D converter 24 to the one-chip microcomputer 25 exceeds the predetermined threshold when the light from the flash lamp FL enters the quartz probe 18. That is, when the flash lamp FL emits light, a part of the light goes directly into the chamber 6 and the other part is once reflected by the reflector 52 and then goes into the chamber 6. A part of the light emitted from the flash lamp FL of the lamp house 5 to the inside of the chamber 6 enters the tip of the quartz probe 18. The light incident on the quartz probe 18 is guided to the photodiode 21 of the waveform measuring unit 20 by the optical fiber 17.

  The photodiode 21 generates a photocurrent according to the intensity of light incident on the quartz probe 18. Since the photodiode 21 has a very short response time, it can follow the irradiation light from the flash lamp FL whose intensity changes dramatically in a short time. The current generated in the photodiode 21 is converted into a voltage signal that can be easily handled by the current-voltage conversion circuit 22.

  The voltage signal output from the current-voltage conversion circuit 22 is amplified by the amplification circuit 23 and then converted into a digital signal suitable for handling by the computer by the high-speed A / D converter 24. The level of the digital signal output from the high-speed A / D converter 24 becomes the input voltage to the one-chip microcomputer 25. When the flash lamp FL starts to emit light, the photodiode 21 generates a photocurrent, and the input voltage to the one-chip microcomputer 25 becomes equal to or higher than a predetermined threshold value, the process proceeds to step S12 and the time measurement by the timer is started. At the same time, sampling in steps S13 to S15 is started.

  In step S13, the level of the digital signal input to the one-chip microcomputer 25 is stored as data in the memory (the memory of the one-chip microcomputer 25) together with the sampling time from the start of timing. After sampling one piece of data in this way, the process proceeds to step S14 and waits for a predetermined time. The waiting time in step S14 is a sampling interval, and an arbitrary time can be set within a range acceptable as hardware of the waveform measuring unit 20, and is set to 0.1 milliseconds in the present embodiment. Yes.

  Next, it progresses to step S15 and it is determined whether the preset waveform acquisition time passed. The waveform acquisition time here is the total time for sampling, and an arbitrary time can be set. In this embodiment, the waveform acquisition time is set to 10 milliseconds. If the preset waveform acquisition time has not elapsed, the process returns to step S13 to again store the digital signal level at that time in the memory. Steps S13 to S15 are repeated until the waveform acquisition time elapses. That is, the one-chip microcomputer 25 repeats the sampling of the level of the digital signal output from the high-speed A / D converter 24 at a predetermined interval for a predetermined time, and sequentially stores the sampled data in the memory together with the sampling time. In the present embodiment, the one-chip microcomputer 25 repeats sampling of the digital signal output from the high-speed A / D converter 24 for 10 milliseconds at intervals of 0.1 milliseconds.

  Data thus repeatedly sampled at a constant time interval and sequentially stored in the memory constitutes a time waveform of the intensity of light incident on the quartz probe 18. That is, if the data stored in the memory of the one-chip microcomputer 25 is plotted in time series along the sampling time, a time waveform of the intensity of light incident on the quartz probe 18 is drawn. For example, if light irradiation is performed with the intensity waveform as shown in FIG. 11 from the flash lamp FL of the lamp house 5, the intensity waveform of the light irradiated inside the chamber 6 is substantially the same, and the one-chip microcomputer 25 The time waveform of the intensity of the light acquired by is as shown in FIG.

  When acquiring a reference waveform of the intensity of light irradiated to the inside of the chamber 6 in step S1 of FIG. 8, light irradiation may be performed from the flash lamp FL while a dummy wafer or the like is carried into the chamber 6. Light irradiation may be performed from the flash lamp FL in the absence of a wafer. The reference waveform is a time waveform of light intensity serving as a reference in the abnormality detection processing in step S6, and is an intensity waveform of light irradiated into the chamber 6 when normal light irradiation is performed from the flash lamp FL. . Therefore, when acquiring the reference waveform, it is necessary that normal light irradiation is performed from the flash lamp FL and that the waveform measurement unit 20 performs normal waveform acquisition. For this reason, it is preferable that the reference waveform acquisition process in step S1 of FIG. 8 is repeated a plurality of times, and when the obtained time waveforms of the light intensity are substantially matched, it is used as the reference waveform. The reference waveform obtained in step S1 is transferred to the main controller 3 and stored in the waveform storage unit 35 (step S2 in FIG. 8).

  On the other hand, when the processing waveform is acquired in step S4 of FIG. 8, light irradiation is performed from the flash lamp FL in a state where the semiconductor wafer W to be processed is held at the processing position by the holding unit 7, and the chamber 6 A time waveform of the intensity of light irradiated inside is acquired. That is, the processing waveform is an intensity waveform of light irradiated to the inside of the chamber 6 when the semiconductor wafer W to be processed is irradiated from the flash lamp FL. Therefore, acquisition of the processing waveform is executed only once for one semiconductor wafer W. The processing waveform acquired in step S4 is also transferred to the main controller 3 and stored in the waveform storage unit 35 (step S5 in FIG. 8). In the waveform storage unit 35, the processing waveform acquired by the waveform measuring unit 20 is accumulated for each semiconductor wafer W to be processed.

<2-4. Processing abnormality detection processing>
Next, the process abnormality detection process in step S6 of FIG. 8 will be described. The reference waveform and the processing waveform are stored in the waveform storage unit 35 of the main controller 3 until the process proceeds to step S6, and the abnormality detection unit 37 compares them to perform the processing abnormality detection process.

<2-4-1. Difference calculation>
16 to 20 are diagrams for explaining comparison between the reference waveform and the processing waveform. In the example of FIG. 16, the abnormality detection unit 37 performs the abnormality detection process by calculating the difference between the reference waveform and the processing waveform in a predetermined time range. The waveform storage unit 35 stores the level of the digital signal output from the high-speed A / D converter 24 together with the sampling time. The abnormality detection unit 37 calculates the difference between the signal level of the reference waveform and the signal level of the processing waveform at the same sampling time within a predetermined time range. If the difference value exceeds a preset allowable range, the abnormality detection unit 37 does not perform normal light irradiation from the flash lamp FL on the semiconductor wafer W to be processed. Therefore, it is determined that the processing quality of the semiconductor wafer W cannot be maintained.

  The difference value is preferably calculated at a plurality of points. The time range for calculating the difference can be set to an arbitrary value. In the example of FIG. 16, the difference value between the reference waveform and the processing waveform is calculated for a plurality of sampling times at a constant time interval (for example, 0.1 milliseconds) over the entire time range of the reference waveform. The difference value may be calculated only in the time range. In this case, it is preferable to set the time range for calculating the difference in the vicinity including the peak of the reference waveform. Since the vicinity of the peak of the intensity waveform of the irradiation light has a great influence on the processing result, the processing quality can be maintained at a higher level by calculating the difference value in the vicinity of the peak and detecting the processing abnormality. Further, when setting a partial time range, it may be set at a plurality of locations (for example, set to each peak if the reference waveform has a plurality of peaks). Furthermore, the time interval for calculating the difference can also be set to an arbitrary value (however, it is an integral multiple of the waiting time in step S14 in FIG. 15).

  Further, the difference value may be integrated in the time range in which the calculation is performed, and the processing abnormality may be detected by comparing the integrated values.

  If the process abnormality is detected with the difference value exceeding the allowable range, the abnormality detection unit 37 displays an error on the display unit of the main controller 3. As the contents of the error display, for example, a difference value exceeding the allowable range and its sampling time may be displayed. Further, the reference waveform and the processing waveform itself as shown in FIG. 16 may be graphically displayed.

<2-4-2. Comparison of integral values>
In the example of FIG. 17, the abnormality detection unit 37 performs an abnormality detection process by comparing the integrated value of the reference waveform and the integrated value of the processing waveform in a predetermined time range. FIG. 17A shows the integrated value of the reference waveform, and FIG. 17B shows the integrated value of the processed waveform. The waveform storage unit 35 stores the level of the digital signal output from the high-speed A / D converter 24 together with the sampling time. The abnormality detection unit 37 calculates an integrated value of the signal level of the reference waveform and an integrated value of the signal level of the processing waveform within a predetermined time range. When the ratio between the integrated value of the reference waveform and the integrated value of the processing waveform is out of a preset allowable range (for example, 99% to 101%), the abnormality detection unit 37 sets the processing target. It is determined that the semiconductor wafer W is not normally irradiated with light from the flash lamp FL, and the processing quality of the semiconductor wafer W cannot be maintained.

  The time range for calculating the integral value can be set to an arbitrary value. For example, as shown in FIG. 17, the integral value may be calculated over the entire time range of the intensity waveform, or may be calculated only in a part of the time range. When setting a partial time range, it is a matter of course that a common integration time range is used for the reference waveform and the processing waveform. When setting a partial time range, it is preferable to set the time range in the vicinity including the peak of the reference waveform. Since the vicinity of the peak of the intensity waveform of the irradiation light has a great influence on the processing result, the processing quality can be maintained at a higher level if the processing abnormality is detected by calculating the integral value in the vicinity of the peak. Further, when setting a partial time range, it may be set at a plurality of locations (for example, set to each peak if the reference waveform has a plurality of peaks).

  When a process abnormality is detected, the abnormality detection unit 37 displays an error on the display unit of the main controller 3. As the contents of the error display, for example, the integrated values of the reference waveform and the processing waveform or the ratio thereof may be displayed. Further, the reference waveform and the processing waveform itself as shown in FIG. 17 may be displayed graphically.

<2-4-3. Comparison of maximum values>
In the example of FIG. 18, the abnormality detection unit 37 performs an abnormality detection process by comparing the maximum value of the reference waveform with the maximum value of the processing waveform. FIG. 18A shows a reference waveform, and FIG. 18B shows a processing waveform. The waveform storage unit 35 stores the level of the digital signal output from the high-speed A / D converter 24 together with the sampling time. The abnormality detection unit 37 compares the maximum value SS _MAX of the signal level of the reference waveform with the maximum value SP _MAX of the signal level of the processing waveform. When the ratio between the maximum value SS _MAX of the reference waveform and the maximum value SP _MAX of the processing waveform is out of a preset allowable range (for example, 99% to 101%), the abnormality detection unit 37 It is determined that the semiconductor wafer W to be processed is not normally irradiated with light from the flash lamp FL, and the processing quality of the semiconductor wafer W cannot be maintained.

In the example of FIG. 18, since only the highest value is compared, the sampling time of the highest value SS _MAX of the reference waveform may be different from the sampling time of the highest value SP _MAX of the processing waveform. If the abnormality detection process is performed only by comparing the maximum values of the intensity waveforms, the sampling time data is not necessarily required. Therefore, in order to save the memory of the one-chip microcomputer 25 and the waveform storage unit 35, only the level of the digital signal output from the high-speed A / D converter 24 may be stored. Furthermore, since only the maximum values of the reference waveform and the processing waveform need be acquired, a peak hold circuit may be used instead of the one-chip microcomputer 25.

  When a process abnormality is detected, the abnormality detection unit 37 displays an error on the display unit of the main controller 3. As the contents of the error display, for example, the maximum values of the reference waveform and the processing waveform or the ratio thereof may be displayed. Further, the reference waveform and the processing waveform itself as shown in FIG. 18 may be displayed graphically.

<2-4-4. Level comparison at any time>
In the example of FIG. 19, the abnormality detection unit 37 performs an abnormality detection process by comparing the intensity value of the reference waveform with the intensity value of the processing waveform at a predetermined time. FIG. 19A shows a reference waveform, and FIG. 19B shows a processing waveform. The waveform storage unit 35 stores the level of the digital signal output from the high-speed A / D converter 24 together with the sampling time. The abnormality detection unit 37 compares the signal level value SPx of the reference waveform at the predetermined sampling time tx with the signal level value SPx of the processing waveform at the sampling time tx. When the ratio between the intensity value SSx of the reference waveform and the intensity value SPx of the processing waveform at the sampling time tx is out of a preset allowable range (for example, 99% to 101%), an abnormality is detected. The unit 37 determines that the semiconductor wafer W to be processed is not normally irradiated with light from the flash lamp FL, and the processing quality of the semiconductor wafer W cannot be maintained.

  When a process abnormality is detected, the abnormality detection unit 37 displays an error on the display unit of the main controller 3. As the contents of the error display, for example, the intensity values at the sampling time tx of the reference waveform and the processing waveform, or the ratio thereof may be displayed. Further, the reference waveform and the processed waveform itself as shown in FIG. 19 may be displayed graphically.

<2-4-5. Comparison of peak intensity>
In the example of FIG. 20, the abnormality detection unit 37 compares the intensity value of the nth peak (n is an integer equal to or greater than 1) of the reference waveform with the intensity value of the nth peak of the processing waveform, and performs the abnormality detection process. Do. FIG. 20A shows a reference waveform, and FIG. 20B shows a processing waveform. The waveform storage unit 35 stores the level of the digital signal output from the high-speed A / D converter 24 together with the sampling time. The abnormality detection unit 37 compares the intensity value SSn of the nth peak of the reference waveform with the intensity value SPn of the nth peak of the processing waveform. When the ratio between the intensity value SSn of the nth peak of the reference waveform and the intensity value SPn of the nth peak of the processed waveform is out of a preset allowable range (for example, 99% to 101%). In this case, the abnormality detection unit 37 determines that the semiconductor wafer W to be processed is not normally irradiated with light from the flash lamp FL, and the processing quality of the semiconductor wafer W cannot be maintained.

  As described above, the vicinity of the peak of the intensity waveform of the irradiation light has a great influence on the processing result. For this reason, it is effective from the viewpoint of maintaining the processing quality to detect the abnormality by comparing the peak intensity values of the reference waveform and the processing waveform. The number of peaks to be compared is not limited to one. When the reference waveform includes a plurality of peaks as in the example of FIG. 20, the intensity values are compared for the plurality of peaks. May be.

  When a process abnormality is detected, the abnormality detection unit 37 displays an error on the display unit of the main controller 3. As the contents of the error display, for example, the intensity values of the respective peaks of the reference waveform and the processing waveform or the ratio thereof may be displayed. Further, the reference waveform and the processing waveform itself as shown in FIG. 20 may be displayed graphically.

<2-4-6. Peak time comparison>
In the example of FIG. 20, the abnormality detection unit 37 compares the time of the nth peak of the reference waveform (n is an integer equal to or greater than 1) with the time of the nth peak of the processing waveform, and performs abnormality detection processing. You may make it do. The abnormality detection unit 37 compares the time tSn of the nth peak of the reference waveform with the time tPn of the nth peak of the processing waveform. When the time tSn of the nth peak of the reference waveform and the time tPn of the nth peak of the processing waveform deviate beyond a preset allowable range, the abnormality detection unit 37 determines whether to process It is determined that the semiconductor wafer W is not normally irradiated with light from the flash lamp FL, and the processing quality of the semiconductor wafer W cannot be maintained.

  Since the vicinity of the peak of the intensity waveform of the irradiation light has a great influence on the processing result, it is effective to detect the abnormality by comparing the peak times of the reference waveform and the processing waveform from the viewpoint of maintaining the processing quality. Note that the number of peaks to be compared is not limited to one, and when a plurality of peaks are included in the reference waveform as in the example of FIG. 20, time comparison is performed for a plurality of peaks. Also good.

  When a process abnormality is detected, the abnormality detection unit 37 displays an error on the display unit of the main controller 3. As the contents of the error display, for example, the time of each peak of the reference waveform and the processing waveform or the time difference between them may be displayed. Further, the reference waveform and the processing waveform itself as shown in FIG. 20 may be displayed graphically.

<3. Effect>
In this embodiment, a change in the intensity of light irradiated into the chamber 6 from the flash lamp FL having a short irradiation time is reliably detected by the photodiode 21 having a very short response time, and this is detected by the one-chip microcomputer 25. It is acquired as a time waveform of intensity. Then, the reference waveform and the processing waveform acquired by the one-chip microcomputer 25 are respectively transferred to the waveform storage unit 35 of the main controller 3, and the abnormality detection unit 37 compares the reference waveform with the processing waveform and performs an abnormality detection process. Yes.

  The technique for detecting the energy of the light irradiated inside the chamber 6 as disclosed in Patent Document 1 cannot measure the time waveform itself of the light intensity. On the other hand, as described above, not only the impurity activation process but also the recovery process of the crystal defect introduced at a position slightly deeper than the impurity implantation layer at the time of ion implantation is performed from the flash lamp FL. The light intensity waveform itself has a great influence on the processing result.

  According to the present embodiment, the time waveform itself of the intensity of light emitted from the flash lamp FL to the inside of the chamber 6 can be measured and acquired by the waveform measuring unit 20. Then, a reference waveform that is a time waveform of light intensity when normal light irradiation is performed from the flash lamp FL and a time of light intensity when light irradiation is performed from the flash lamp FL to the semiconductor wafer W to be processed. Abnormalities in light irradiation are detected by comparing the processed waveform, which is a waveform. Since the time waveforms of the light intensity are compared, it is possible to detect abnormalities in the light irradiation from the flash lamp FL with higher accuracy than before, and as a result, the processing quality of the semiconductor wafer W is maintained at a high level. can do.

<4. Modification>
While the embodiments of the present invention have been described above, the present invention can be modified in various ways other than those described above without departing from the spirit of the present invention. For example, the configuration of the heat treatment apparatus 1 may be as shown in FIGS. In the above embodiment, the quartz probe 18 and the waveform measuring unit 20 are connected via the optical fiber 17, but in the example shown in FIG. 21, the quartz probe 18 and the waveform measuring unit 20 are directly connected. Even if configured as shown in FIG. 21, the same processing as in the above embodiment can be performed.

  In the example shown in FIG. 22, a quartz window 19 is used instead of the quartz probe 18 of the above embodiment. The quartz window 19 is installed on the chamber bottom 62 which is the bottom wall surface of the chamber 6. The quartz window 19 is connected to the waveform measuring unit 20 via the optical fiber 17. In the example shown in FIG. 23, the quartz window 19 and the waveform measuring unit 20 are directly connected. 22 and FIG. 23, a part of the light emitted from the flash lamp FL to the inside of the chamber 6 enters the quartz window 19, and the waveform measurement process similar to that in the above embodiment is executed. . That is, the quartz probe 18 in FIGS. 1 and 21 and the quartz window 19 in FIGS. 22 and 23 all function as an incident portion where light irradiated from the flash lamp FL of the lamp house 5 into the chamber 6 enters. The waveform measuring unit 20 measures the time waveform of the intensity of the incident light. 21 to 23, the configuration other than the waveform measurement mechanism is the same as that in the above embodiment, and the same elements as those in the above embodiment are denoted by the same reference numerals.

  Further, the structure for receiving the light irradiated from the flash lamp FL into the chamber 6 and guiding it to the waveform measuring unit 20 is not limited to the forms shown in FIGS. 1, 21 to 23. For example, the light guiding structure disclosed in Patent Document 1 may be used. Further, a quartz probe 18 and a quartz window 19 may be provided in the lamp house 5 to directly measure light from the flash lamp FL.

  In the above embodiment, the sampling of the digital signal is started when the input voltage from the high-speed A / D converter 24 to the one-chip microcomputer 25 becomes equal to or higher than a predetermined threshold. However, the present invention is not limited to this. For example, the sampling may be started in synchronization with the timing of outputting the pulse signal from the pulse generator 31 of the main controller 3. Further, sampling may be started in synchronization with the timing at which the trigger circuit 97 applies a voltage to the trigger electrode 91. Alternatively, sampling may be started when the slope of the input voltage from the high-speed A / D converter 24 to the one-chip microcomputer 25 becomes a predetermined value or more. Further, the sampling may be started when a predetermined time elapses after the transfer opening 66 is closed by the gate valve 185.

  In the above-described embodiment, the reference waveform is obtained by performing normal light irradiation from the flash lamp FL prior to the processing of the semiconductor wafer W to be processed. When the semiconductor wafer W is subjected to the light irradiation heat treatment, the time waveform of the intensity of the light irradiated into the chamber 6 may be acquired as the reference waveform. Further, a time waveform of the intensity of light irradiated into the chamber 6 when the semiconductor wafer W in the lot is subjected to the light irradiation heat treatment may be acquired as a reference waveform. Furthermore, as the reference waveform, a waveform previously stored in the waveform storage unit 35 may be used, a waveform set manually, or downloaded from outside the apparatus. May be.

  Further, when performing the abnormality detection process by calculating the difference (FIG. 16) or comparing the integral values (FIG. 17), the time range in which the calculation is performed may be automatically set. Specifically, the abnormality detection unit 37 detects the peak of the reference waveform, and sets a time range having a length set in advance so as to include the detected peak. In this way, it is possible to set a time range in which calculation is performed reliably in the vicinity of the peak.

  Further, in the above embodiment, the abnormality detection process is performed every time the light irradiation heat treatment of one semiconductor wafer W is completed (step S6 in FIG. 8), but the light irradiation heat treatment of all the semiconductor wafers W is performed. The process abnormality detection process may be performed after the process ends. That is, step S6 may be executed after step S7 in FIG.

  Further, in the above embodiment, the time waveform of the light emission intensity is adjusted by controlling the energization to the flash lamp FL by the switching element 96, but from the flash lamp FL without using the switching element 96. Even if the light emission is a simple single pulse intensity waveform, the intensity waveform of the irradiation light can be measured by applying the technique according to the present invention.

  In the above embodiment, the lamp house 5 is provided with 30 flash lamps FL. However, the present invention is not limited to this, and the number of flash lamps FL can be any number. The flash lamp FL is not limited to a xenon flash lamp, and may be a krypton flash lamp.

  In the above-described embodiment, the IGBT is used as the switching element 96. However, the present invention is not limited to this, and other transistors other than the IGBT may be used. The waveform of the input pulse signal may be used. Any element can be used as long as the circuit can be turned on and off accordingly. However, since a considerable amount of power is consumed for the light emission of the flash lamp FL, it is preferable to employ an IGBT or a GTO (Gate Turn Off) thyristor suitable for handling a large amount of power as the switching element 96.

  The substrate to be processed by the heat treatment apparatus according to the present invention is not limited to a semiconductor wafer, and may be a glass substrate used for a liquid crystal display device or the like.

DESCRIPTION OF SYMBOLS 1 Heat processing apparatus 3 Main controller 4 Holding part raising / lowering mechanism 5 Lamphouse 6 Chamber 7 Holding part 17 Optical fiber 18 Quartz probe 19 Quartz window 20 Waveform measuring part 21 Photodiode 22 Current voltage conversion circuit 23 Amplifier circuit 24 High-speed A / D converter 25 One Chip microcomputer 35 Waveform storage unit 37 Abnormality detection unit 60 Upper opening 61 Chamber window 62 Chamber bottom 63 Chamber side 65 Heat treatment space 71 Hot plate 72 Susceptor 96 Switching element FL Flash lamp W Semiconductor wafer

Claims (18)

A heat treatment apparatus for heating a substrate by irradiating the substrate with light,
A chamber for housing the substrate;
A holding unit for holding the substrate in the chamber;
A flash lamp for irradiating the substrate held by the holding unit with light;
A switching element for controlling a current flowing through the flash lamp;
A signal setting unit for setting a waveform of a signal applied to the gate of the switching element;
A signal generating unit that outputs a signal according to the waveform of the signal set by the signal setting unit and applies it to the gate of the switching element;
A waveform measuring unit that measures a time waveform of the intensity of light emitted from the flash lamp to the inside of the chamber;
A reference waveform which is a time waveform of light intensity when a signal having a predetermined waveform is applied to the gate of the switching element and normal light irradiation is performed from the flash lamp, and the gate of the switching element has the predetermined waveform. A waveform storage unit for storing a processing waveform which is a time waveform of light intensity when a signal is applied and light irradiation is performed on the substrate to be processed from the flash lamp;
An abnormality detection unit that performs an abnormality detection process by comparing the reference waveform and the processing waveform;
A heat treatment apparatus comprising: The heat treatment apparatus according to claim 1, wherein
The abnormality detection unit performs an abnormality detection process by calculating a difference between the reference waveform and the processing waveform in a predetermined time range. The heat treatment apparatus according to claim 1, wherein
The abnormality detection unit performs an abnormality detection process by comparing an integrated value of the reference waveform with an integrated value of the processing waveform in a predetermined time range. The heat treatment apparatus according to claim 1, wherein
The abnormality detection unit performs an abnormality detection process by comparing the highest value of the reference waveform with the highest value of the processing waveform. The heat treatment apparatus according to claim 1, wherein
The abnormality detection unit performs an abnormality detection process by comparing an intensity value of the reference waveform with an intensity value of the processing waveform at a predetermined time. The heat treatment apparatus according to claim 1, wherein
The abnormality detection unit performs an abnormality detection process by comparing an intensity value of an nth peak (n is an integer of 1 or more) of the reference waveform with an intensity value of an nth peak of the processing waveform. Heat treatment equipment. The heat treatment apparatus according to claim 1, wherein
The abnormality detection unit performs an abnormality detection process by comparing the time of the n-th peak (n is an integer equal to or greater than 1) of the reference waveform and the time of the n-th peak of the processing waveform. Heat treatment equipment. In the heat treatment apparatus according to claim 2 or 3,
The heat treatment apparatus, wherein the abnormality detection unit sets the predetermined time range so as to include a peak of the reference waveform. In the heat processing apparatus in any one of Claims 1-8,
The waveform measurement unit includes a photodiode, and is a heat treatment apparatus. In the heat treatment apparatus according to any one of claims 1 to 9,
The heat treatment apparatus, wherein the switching element is an insulated gate bipolar transistor. A heat treatment method for heating a substrate by irradiating light to the substrate held in a chamber from a flash lamp,
The time of the intensity of light irradiated to the inside of the chamber when a signal having a predetermined waveform is applied to the gate of the switching element that controls the current flowing through the flash lamp and normal light irradiation is performed from the flash lamp. A reference waveform acquisition step of acquiring a waveform as a reference waveform;
Processing the time waveform of the intensity of the light applied to the inside of the chamber when the signal of the predetermined waveform is applied to the gate of the switching element and the substrate to be processed is irradiated with light from the flash lamp. Processing waveform acquisition step to acquire as a waveform;
An abnormality detection step of performing an abnormality detection process by comparing the reference waveform and the processing waveform;
A heat treatment method comprising: The heat treatment method according to claim 11,
The abnormality detection step performs an abnormality detection process by calculating a difference between the reference waveform and the processing waveform in a predetermined time range. The heat treatment method according to claim 11,
In the abnormality detection step, an abnormality detection process is performed by comparing an integrated value of the reference waveform with an integrated value of the processing waveform in a predetermined time range. The heat treatment method according to claim 11,
In the abnormality detection step, an abnormality detection process is performed by comparing a maximum value of the reference waveform with a maximum value of the processing waveform. The heat treatment method according to claim 11,
In the abnormality detection step, an abnormality detection process is performed by comparing an intensity value of the reference waveform with an intensity value of the processing waveform at a predetermined time. The heat treatment method according to claim 11,
In the abnormality detection step, an abnormality detection process is performed by comparing the intensity value of the nth peak (n is an integer of 1 or more) of the reference waveform with the intensity value of the nth peak of the processing waveform. A heat treatment method. The heat treatment method according to claim 11,
In the abnormality detection step, an abnormality detection process is performed by comparing the time of the nth peak (n is an integer of 1 or more) of the reference waveform and the time of the nth peak of the processing waveform. Heat treatment method. The heat treatment method according to any one of claims 11 to 17,
The heat treatment method, wherein the switching element is an insulated gate bipolar transistor.

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