JP2014045067A - Heat treatment method and heat treatment apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heat treatment method and a heat treatment apparatus, allowing light energy absorbed by a substrate being a treatment object when the substrate is irradiated with flash light to be accurately calculated.SOLUTION: Spectral emissivity of a semiconductor wafer is calculated using spectral intensity of a halogen lamp and spectral intensity of reflected light obtained by irradiating a surface of the semiconductor wafer being a treatment object with halogen light from the halogen lamp. On the basis of the spectral emissivity of the semiconductor wafer and spectral intensity of a flashlamp, light energy absorbed by the semiconductor wafer when the semiconductor wafer is irradiated with flash light from the flashlamp is calculated. Since the calculation is made by taking account of a difference in spectral distribution of the halogen lamp used for measuring reflected light intensity and the flashlamp used for heat treatment and also taking account of spectral characteristics of the emissivity of the semiconductor wafer, light energy absorbed by the semiconductor wafer when the semiconductor wafer is irradiated with the flash light can be accurately calculated.

Description

  The present invention relates to a heat treatment method and a heat treatment apparatus for heating a thin plate-shaped precision electronic substrate (hereinafter simply referred to as “substrate”) such as a semiconductor wafer or a glass substrate for a liquid crystal display device by irradiating flash light. .

  Conventionally, a lamp annealing apparatus using a halogen lamp has been generally used in an impurity activation process of a semiconductor wafer after ion (impurity) implantation. In such a lamp annealing apparatus, the semiconductor wafer is heated (annealed) to a temperature of about 1000 ° C. to 1100 ° C., for example, to activate the impurities of the semiconductor wafer. In such a heat treatment apparatus, the temperature of the substrate is raised at a rate of several hundred degrees per second by using the energy of light irradiated from the halogen lamp.

  On the other hand, in recent years, as semiconductor devices have been highly integrated, it is desired to reduce the junction depth as the gate length becomes shorter. However, even when the impurity activation of the semiconductor wafer is performed using the above-described lamp annealing apparatus that raises the temperature of the semiconductor wafer at a speed of about several hundred degrees per second, impurities such as boron and phosphorus implanted in the semiconductor wafer are heated. It was found that the phenomenon of deep diffusion occurs. When such a phenomenon occurs, there is a concern that the junction depth becomes deeper than required, which hinders good device formation.

  For this reason, only the surface of the semiconductor wafer into which impurities have been implanted is irradiated by flashing the surface of the semiconductor wafer using a xenon flash lamp (hereinafter simply referred to as “flash lamp” means xenon flash lamp). There has been proposed a technique for raising the temperature of the material in an extremely 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. It has also been found that if the flash irradiation is performed 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 by a flash lamp for a very short time, only impurity activation can be performed without deeply diffusing the impurities.

  However, in a heat treatment apparatus using a flash lamp, a very large amount of light energy is irradiated onto the wafer surface in a very short time, so that the surface temperature rises rapidly and only the wafer surface expands rapidly. It has also been found that if the energy irradiated from the flash lamp is excessive, only the surface expands rapidly, resulting in slippage on the wafer surface, or in the worst case, wafer cracking. On the other hand, if the irradiation energy is low, impurity activation cannot be performed. Therefore, it is important to optimize the range of light energy emitted from the flash lamp.

  In general, in the case of a flash lamp with an extremely short irradiation time, it is impossible to perform feedback control of the lamp output based on the temperature measurement result of a semiconductor wafer. Therefore, ion implantation is performed on a bare wafer that has not been patterned, and the wafer is actually The characteristics (for example, sheet resistance value) after processing after light irradiation are measured, and the light energy irradiated from the flash lamp is adjusted based on the result.

  However, the wafer to be actually processed is a pattern-formed wafer, and often has a light absorption characteristic different from that of a plain bare wafer. In general, even when irradiated with light of the same energy, a patterned wafer tends to absorb more light energy than a bare wafer. For this reason, even if the irradiation energy is optimized in the bare wafer, there has been a problem that the wafer to be actually processed absorbs more light energy, resulting in wafer cracking. In order to prevent this, it is necessary to correct the appropriate irradiation energy value on the bare wafer for each wafer to be processed.

  In order to solve such a problem, Patent Documents 1 to 3 calculate the light energy values absorbed by measuring the reflected light intensity of the bare wafer and the semiconductor wafer that is actually processed, and based on them. It is disclosed that the light energy absorption ratio of the wafer to be processed with respect to the bare wafer is obtained. And the technique of calculating the appropriate energy value of the flash light which should be irradiated to a process target wafer from the optical energy absorption ratio and the appropriate energy value of the light irradiated to a bare wafer is disclosed.

JP-A-2005-39213 JP 2007-13047 A JP 2008-159994 A

  However, the light source generally has a spectral characteristic that the intensity depends on the wavelength, and the spectral distribution of the intensity of the continuous lighting light source used when measuring the reflected light intensity is different from the spectral distribution of the intensity of the flash lamp. For this reason, even if the reflected light intensity of a semiconductor wafer is measured using a continuous lighting light source, and the light energy absorbed by the wafer upon flash light irradiation is calculated based on the measured intensity, the actual absorbed energy value is different. There was a possibility. Further, the emissivity (or reflectance) of the semiconductor wafer itself is not uniform for all wavelengths and has spectral characteristics, but in the techniques disclosed in Patent Documents 1 to 3, the spectral emissivity of the semiconductor wafer is It was not considered. For this reason, there has been a problem that it is impossible to accurately calculate the light energy and the like absorbed by the wafer during flash light irradiation.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a heat treatment method and a heat treatment apparatus capable of accurately calculating the light energy absorbed by the substrate to be treated at the time of flash light irradiation.

  In order to solve the above-mentioned problems, the invention of claim 1 is a heat treatment method for heating a substrate to be processed by irradiating the substrate to be processed with flash light, and (a) obtaining a spectral intensity of a halogen lamp; (b) measuring the spectral intensity of the reflected light obtained by irradiating the surface of the substrate to be processed from the halogen lamp with the halogen light; and (c) spectroscopic analysis of the halogen lamp obtained in the step (a). Calculating the spectral emissivity of the substrate to be processed from the intensity and the spectral intensity of the reflected light obtained in the step (b), and (d) the spectral emissivity of the substrate to be processed and the spectral intensity of the flash lamp. And calculating a light energy absorbed by the substrate to be processed when flash light is irradiated onto the surface of the substrate to be processed from the flash lamp.

  Further, the invention of claim 2 is the heat treatment method according to the invention of claim 1, in which (e) the processing target is obtained at the time of flash light irradiation from the light energy absorbed by the processing target substrate obtained in the step (d). The method further includes a step of calculating a temperature reached by the surface of the substrate.

  The invention of claim 3 is the heat treatment method according to the invention of claim 1 or claim 2, wherein (f) the spectral intensity of the flash lamp and the processing result when flash light of the spectral intensity is irradiated. Obtaining a spectral emissivity of a standard substrate whose correlation is known, and (g) based on the spectral emissivity of the standard substrate and the spectral intensity of the flash lamp, from the flash lamp to the surface of the standard substrate. A step of calculating the light energy absorbed by the standard substrate when the flash light is irradiated to (h) the calculation result obtained in the step (d) and the calculation result obtained in the step (g) And (i) calculating a light energy absorption ratio of the substrate to be processed relative to the standard substrate based on the correlation substrate and the light energy absorption ratio. And a step of determining the spectral intensity of the Schw light.

  According to a fourth aspect of the present invention, in a heat treatment apparatus that heats a processing target substrate by irradiating the processing target substrate with flash light, a halogen lamp that emits halogen light, a flash lamp that emits flash light, A reflected light intensity measuring unit that measures the spectral intensity of reflected light obtained by irradiating the surface of the substrate to be processed from the halogen lamp with the spectral intensity of the halogen lamp and the spectral intensity of the reflected light. The spectral emissivity of the substrate is calculated, and based on the spectral intensity and the spectral emissivity of the flash lamp, the processing target substrate absorbs when the flash lamp is irradiated with flash light from the flash lamp. And an absorbed energy calculation unit for calculating light energy.

  Further, the invention of claim 5 is the heat treatment apparatus according to claim 4, wherein the surface of the substrate to be processed is irradiated with flash light from the light energy absorbed by the substrate to be processed calculated by the absorbed energy calculating unit. The apparatus further includes a temperature calculation unit that calculates a temperature at which the temperature reaches.

  The invention of claim 6 is the heat treatment apparatus according to claim 4 or claim 5, wherein the correlation between the spectral intensity of the flash lamp and the processing result when the standard substrate is irradiated with flash light of the spectral intensity. The relationship is known, and the absorption energy calculation unit is configured to irradiate flash light from the flash lamp onto the surface of the standard substrate based on the spectral emissivity of the standard substrate and the spectral intensity of the flash lamp. Calculate the light energy absorbed by the standard substrate, calculate the light energy absorption ratio of the substrate to be processed with respect to the standard substrate when flash light is irradiated from the flash lamp, and calculate the correlation and the light energy absorption ratio. A flash light intensity determination unit that determines the spectral intensity of the flash light irradiated to the substrate to be processed, based on Characterized in that it comprises a.

  According to the first to third aspects of the present invention, the spectral emission of the substrate to be processed is obtained from the spectral intensity of the halogen lamp and the spectral intensity of the reflected light obtained by irradiating the surface of the substrate to be processed from the halogen lamp. To calculate the light energy absorbed by the target substrate when the flash lamp is irradiated with flash light from the flash lamp based on the obtained spectral emissivity and the spectral intensity of the flash lamp. The light energy absorbed by the substrate to be processed can be accurately calculated in consideration of the spectral characteristics of the halogen lamp, the flash lamp, and the substrate to be processed.

  According to the fourth to sixth aspects of the present invention, the spectral emission of the substrate to be processed is obtained from the spectral intensity of the halogen lamp and the spectral intensity of the reflected light obtained by irradiating the surface of the substrate to be processed from the halogen lamp. To calculate the light energy absorbed by the target substrate when the flash lamp is irradiated with flash light from the flash lamp based on the obtained spectral emissivity and the spectral intensity of the flash lamp. The light energy absorbed by the substrate to be processed can be accurately calculated in consideration of the spectral characteristics of the halogen lamp, the flash lamp, and the substrate to be processed.

It is a top view which shows the heat processing apparatus which concerns on this invention. It is a front view of the heat processing apparatus of FIG. It is a longitudinal cross-sectional view which shows the structure of a flash heating part. It is sectional drawing which shows the gas path of a flash heating part. 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 sectional side view which shows the structure of the flash heating part of FIG. It is a figure which shows the structure of an alignment part. It is a figure for demonstrating the structure of a measurement optical system. It is a block diagram which shows the structure of a control part. It is a flowchart which shows the calculation procedure of the light energy which a semiconductor wafer absorbs. It is a figure which shows spectral intensity, such as a halogen lamp. It is a figure which shows the spectral emissivity of the semiconductor wafer used as a process target. This is the spectral intensity of the flash light emitted from the flash lamp. It is a flowchart which shows the calculation procedure of the surface arrival temperature of a semiconductor wafer. It is a flowchart which shows the calculation procedure of the spectral intensity of flash light.

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

<1. First Embodiment>
First, the overall schematic configuration of the heat treatment apparatus 100 according to the present invention will be briefly described. FIG. 1 is a plan view showing a heat treatment apparatus 100 according to the present invention, and FIG. 2 is a front view thereof. In FIG. 1 and the subsequent drawings, the size and number of each part are exaggerated or simplified as necessary for easy understanding. In addition, in FIGS. 1 and 2 and subsequent figures, an XYZ orthogonal coordinate system in which the Z-axis direction is the vertical direction and the XY plane is the horizontal plane is attached as necessary to clarify the directional relationship. .

  As shown in FIGS. 1 and 2, the heat treatment apparatus 100 includes an indexer unit 101 for loading an unprocessed semiconductor wafer W into the apparatus from outside and unloading the processed semiconductor wafer W outside the apparatus. Alignment unit 130 for positioning the semiconductor wafer W, cooling unit 140 for cooling the semiconductor wafer W after the heat treatment, flash heating unit 160 for performing flash heat treatment on the semiconductor wafer W, the alignment unit 130, the cooling unit 140, and the flash A transport robot 150 that transports the semiconductor wafer W to the heating unit 160 is provided. Further, the heat treatment apparatus 100 includes a control unit 3 that controls the operation mechanism provided in each processing unit and the transfer robot 150 to advance the processing on the semiconductor wafer W.

  The indexer unit 101 loads a plurality of carriers C (two in this embodiment) side by side and loads the unprocessed semiconductor wafers W from the carriers C, and processes the semiconductor wafers processed by the carriers C. And a delivery robot 120 for storing W. The carrier C containing the unprocessed semiconductor wafer W is transported by an automatic guided vehicle (AGV, OHT) or the like and placed on the load port 110, and the carrier C containing the processed semiconductor wafer W is an automatic guided vehicle. Is taken away from the load port 110. Further, the load port 110 is configured such that the carrier C can be moved up and down as indicated by an arrow CU in FIG. 2 so that the delivery robot 120 can take in and out an arbitrary semiconductor wafer W with respect to the carrier C. ing. As a form of the carrier C, in addition to a FOUP (front opening unified pod) for storing the semiconductor wafer W in a sealed space, a standard mechanical interface (SMIF) pod and an OC (open for exposing the stored semiconductor wafer W to the open air) cassette).

  In addition, the delivery robot 120 is capable of sliding movement as indicated by an arrow 120S, turning operation and raising / lowering operation as indicated by an arrow 120R. Thereby, the delivery robot 120 can carry the semiconductor wafer W in and out of the two carriers C and can deliver the semiconductor wafer W to the alignment unit 130 and the cooling unit 140. The delivery / removal robot 120 moves the semiconductor wafer W in and out of the carrier C by sliding the hand 121 and moving the carrier C up and down. Further, the delivery of the semiconductor wafer W between the delivery robot 120 and the alignment unit 130 or the cooling unit 140 is performed by the sliding movement of the hand 121 and the lifting operation of the delivery robot 120.

  The alignment unit 130 is a processing unit that rotates the semiconductor wafer W and directs the semiconductor wafer W in an appropriate direction for subsequent flash heating. The semiconductor wafer W is delivered from the delivery robot 120 to the alignment unit 130 so that the center of the semiconductor wafer W is located at a predetermined position. The alignment unit 130 includes an optical measurement unit 30 described later, and the optical measurement unit 30 measures the reflected light intensity of the semiconductor wafer W and the like.

  The flash heating unit 160, which is a main part of the heat treatment apparatus 100, is a processing unit that performs flash heating processing by irradiating the semiconductor wafer W with flash light (flash light) from the xenon flash lamp FL. The configurations of the flash heating unit 160 and the alignment unit 130 will be described in detail later.

  The cooling unit 140 is configured by placing a quartz plate on the upper surface of a metal cooling plate. Since the temperature of the semiconductor wafer W immediately after the flash heating process is performed by the flash heating unit 160 is high, the semiconductor wafer W is placed on the quartz plate and cooled by the cooling unit 140.

  The transfer robot 150 can be turned around an axis along the vertical direction as indicated by an arrow 150R, and has two link mechanisms composed of a plurality of arm segments, and at the end of the two link mechanisms. Are provided with transfer arms 151a and 151b for holding the semiconductor wafer W, respectively. These transfer arms 151a and 151b are arranged vertically apart from each other by a predetermined pitch, and can be slid linearly in the same horizontal direction independently by a link mechanism. Also, the transfer robot 150 moves up and down the two transfer arms 151a and 151b while moving away from each other by a predetermined pitch by moving up and down a base provided with two link mechanisms.

  In addition, a transfer chamber 170 that houses the transfer robot 150 is provided as a transfer space for the semiconductor wafer W by the transfer robot 150, and the alignment unit 130, the cooling unit 140, and the flash heating unit 160 are connected to the transfer chamber 170. ing. When the transfer robot 150 transfers (inserts / removes) the semiconductor wafer W as a transfer partner to the alignment unit 130, the flash heating unit 160, or the cooling unit 140, first, the transfer arms 151a and 151b are opposed to the transfer partner. Turn. Thereafter (or while turning), the transfer robot 150 moves up and down and is positioned at a height at which one of the transfer arms 151a (151b) transfers the semiconductor wafer W to the transfer partner. Then, the transfer arm 151a (151b) is slid linearly in the horizontal direction, and the transfer partner and the semiconductor wafer W are transferred.

  Gate valves 181 and 182 are provided between the indexer unit 101 and the alignment unit 130 and the cooling unit 140, respectively. Between the transfer chamber 170 and the alignment unit 130, the cooling unit 140 and the flash heating unit 160, respectively. Gate valves 183, 184 and 185 are provided. Then, a high-purity nitrogen gas is supplied from a nitrogen gas supply unit (not shown) so that the inside of the alignment unit 130, the cooling unit 140, and the transfer chamber 170 is kept clean, and excess nitrogen gas is appropriately exhausted. Exhausted from the tube. When the semiconductor wafer W is transported, these gate valves are appropriately opened and closed.

  The alignment unit 130 and the cooling unit 140 are positioned on the forward and return paths of the wafer transfer path between the indexer unit 101 and the transfer robot 150. The alignment unit 130 positions the semiconductor wafer W in order to position the semiconductor wafer W. Is temporarily placed, and the cooling unit 140 temporarily places the semiconductor wafer W in order to cool the semiconductor wafer W after the heat treatment.

  Next, the configuration of the flash heating unit 160 will be described. FIG. 3 is a longitudinal sectional view showing the configuration of the flash heating unit 160. The flash heating unit 160 is a heat treatment unit that irradiates a substantially circular semiconductor wafer W as a substrate with flash light and heats the semiconductor wafer W.

  The flash heating unit 160 includes a substantially cylindrical chamber 6 that houses the semiconductor wafer W, and a lamp house 5 that houses a plurality of flash lamps FL. Note that each operation mechanism provided in the chamber 6 and the lamp house 5 is controlled by the control unit 3 provided in the heat treatment apparatus 100 to advance 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 functions as a quartz window that transmits the flash light emitted from the flash lamp FL 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 (the surface opposite to the side irradiated with the flash light from the flash lamp FL) 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. 4 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. 4, the gas introduction buffer 83 is formed over about ３ of the inner circumference of the chamber side portion 63 on the opposite side of the transfer opening 66 shown in FIG. 3. 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.

  Returning to FIG. 3, the flash heating unit 160 holds the semiconductor wafer W in the horizontal position inside the chamber 6 and performs preheating of the semiconductor wafer W held before the flash light irradiation, while holding the semiconductor wafer W in a substantially posture. 7 and a holding unit raising / lowering mechanism 4 that raises and lowers the holding unit 7 with respect to the chamber bottom 62 which is the bottom surface of the chamber 6. 3 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 the driving part rotates the ball screw 45 under the control of the control part 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 portion 7 connected to the shaft 41 moves between the delivery position of the semiconductor wafer W shown in FIG. 3 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 part 49 has a handle 491 and a rotating shaft 492. By rotating the rotating shaft 492 via the handle 491, the ball screw 45 connected to the rotating shaft 492 is rotated via the timing belt 495 to hold the holding part. 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. 5 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. 6 is a plan view showing the hot plate 71. As shown in FIG. 6, the hot plate 71 includes a disc-shaped zone 711 and an annular zone 712 that are concentrically arranged in the center of a region facing the semiconductor wafer W to be held, and the 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 control unit 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 control unit 3. The temperature control of each zone by the control unit 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 heat treatment 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 heat treatment 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 flash light from the flash lamp FL via 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.

  The xenon flash lamp FL has a rod-shaped glass tube (discharge tube) in which xenon gas is sealed and an anode and a cathode connected to a capacitor at both ends thereof, and an outer peripheral surface of the glass tube. And a triggered electrode. Since xenon gas is an electrical insulator, electricity does not flow into the glass tube under normal conditions even if electric charges are accumulated in the capacitor. However, when the insulation is broken by applying a high voltage to the trigger electrode, the electricity stored in the capacitor flows instantaneously in the glass tube, and light is emitted by excitation of atoms or molecules of xenon at that time. In such a xenon flash lamp FL, the electrostatic energy stored in the capacitor in advance is converted into an extremely short light pulse of 0.1 millisecond to 100 millisecond. It has the feature that it can irradiate strong light.

  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 flash 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. 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.

  In addition to the above-described configuration, the flash heating unit 160 prevents various temperature rises of the heat treatment chamber 6 and the lamp house 5 due to thermal energy generated from the flash lamp FL and the hot plate 71 during the heat treatment of the semiconductor wafer W. A cooling structure is provided. For example, water-cooled tubes (not shown) are provided on the chamber side 63 and the chamber bottom 62 of the heat treatment 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 FIGS. 3 and 7). 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.

  Next, the configuration of the alignment unit 130 will be described. FIG. 8 is a diagram illustrating a configuration of the alignment unit 130. The alignment unit 130 includes a wafer holding unit 132 and an optical measurement unit 30 in a chamber 131. The chamber 131 is a metal housing that houses the semiconductor wafer W. Openings 133 and 134 for accessing the delivery robot 120 and the transfer robot 150 are provided on the side wall of the chamber 131, and the openings are opened and closed by gate valves 181 and 183, respectively. In FIG. 8, illustration of the gate valves 181 and 183 is omitted.

  A wafer holding part 132 is provided at the bottom of the chamber 131. The wafer holding unit 132 includes three support pins 136 (only two are shown for convenience of illustration in FIG. 8) and a motor 135. Three support pins 136 support and place the semiconductor wafer W from the lower surface. The three support pins 136 are connected to each other, and the three support pins 136 are rotated by a motor 135 around a vertical axis. In addition, the alignment unit 130 includes a detection head (not shown), and a notch (notch for a φ300 mm wafer, orientation flat for a φ200 mm wafer) of a semiconductor wafer W that is supported by a support pin 136 and rotates. To detect.

  The optical measurement unit 30 includes a measurement optical system 31, a projector 33 coupled to the measurement optical system 31 via a light projecting optical fiber 32, and a light receiving optical fiber 34 to the measurement optical system 31. And a spectroscope 35 coupled together. Of the components of the optical measurement unit 30, the measurement optical system 31 is fixedly installed on the ceiling portion of the chamber 131, and the other elements are provided outside the chamber 131.

  The projector 33 has a built-in halogen lamp HL. The halogen lamp HL is a filament-type light source that emits light by making the filament incandescent by energizing the filament in a gas obtained by introducing a small amount of a halogen element (iodine, bromine, etc.) into an inert gas such as nitrogen or argon. By introducing a halogen element, it is possible to set the filament temperature to a high temperature while suppressing breakage of the filament. The halogen lamp HL continuously emits a constant amount of halogen light. Light emitted from the halogen lamp HL of the projector 33 is guided to the measurement optical system 31 through the optical fiber 32 for projection.

  FIG. 9 is a diagram for explaining the configuration of the measurement optical system 31. The measurement optical system 31 functions as a light projecting / receiving unit that irradiates the main surface of the semiconductor wafer W supported by the support pins 136 and receives the reflected light from the main surface. In the measurement optical system 31, an achromatic lens 36, a half mirror 37, and a total reflection mirror 38 are arranged along the vertical direction in order from the bottom. Further, a diffuser 39 is disposed along the direction in which the reflected light from the total reflection mirror 38 is directed.

  The half mirror 37 is provided in an attitude that forms an angle of 45 ° with respect to the semiconductor wafer W supported by the support pins 136 (an angle of 45 ° with respect to the horizontal plane), and the emission end of the light projecting optical fiber 32. The light in the horizontal direction from 32a is received and reflected downward in the vertical direction. The light reflected by the half mirror 37 passes through the achromatic lens 36 and travels downward. Thus, the light emitted downward from the measurement optical system 31 is applied to the upper surface of the semiconductor wafer W supported by the support pins 136.

  The reflected light reflected from the upper surface of the semiconductor wafer W sequentially passes through the achromatic lens 36 and the half mirror 37 and is reflected toward the diffuser 39 by the total reflection mirror 38. The reflected light that has entered the diffuser 39 undergoes a diffusion uniformization process and enters the incident end 34 a of the light receiving optical fiber 34. That is, the diffuser 39 is interposed between the incident end 34a of the light receiving optical fiber 34 and the total reflection mirror 38. The incident end surface 39a faces the total reflection mirror 38 and the emission end surface 39b receives light. It faces the incident end 34a of the optical fiber 34 for use. The achromatic lens 36 has a function of focusing the reflected light from the semiconductor wafer W onto the incident end surface 39 a of the diffuser 39.

  The light incident on the light receiving optical fiber 34 is subjected to spectral decomposition processing by the spectroscope 35, and a signal output from the spectroscope 35 as a result of the processing is transmitted to the measuring unit 95. The measuring unit 95 measures the spectral intensity of the light incident on the light receiving optical fiber 34 (that is, the reflected light reflected by the semiconductor wafer W) based on the signal output from the spectroscope 35. A measurement result by the measurement unit 95 is transmitted to the control unit 3.

  The control unit 3 is a controller that manages the entire heat treatment apparatus 100 and controls the flash heating unit 160 and the optical measurement unit 30, as well as the light energy absorbed by the semiconductor wafer W during flash light irradiation as will be described later. calculate. FIG. 10 is a block diagram illustrating a configuration of the control unit 3. The configuration of the control unit 3 as hardware is the same as that of a general computer. That is, the control unit 3 stores a CPU 11 that performs various arithmetic processes, a ROM 12 that is a read-only memory that stores basic programs, a RAM 13 that is a readable / writable memory that stores various information, control software, data, and the like. The magnetic disk 14 to be placed is connected to a bus line 19.

  Further, the measurement unit 95 and the power supply unit 96 of the flash lamp FL are electrically connected to the bus line 19. Further, the projector 33 and the spectroscope 35 of the optical measurement unit 30 are also electrically connected to the bus line 19 via the measurement unit 95. The CPU 11 of the control unit 3 executes processing software stored in the magnetic disk 14 to control these mechanisms, and calculates an optical energy absorbed by the semiconductor wafer W. It functions as a temperature calculation unit that calculates the surface temperature and a flash light intensity determination unit that determines the spectral intensity of the flash light. Further, the control unit 3 adjusts the power supplied from the power supply unit 96 to the flash lamp FL, more specifically, the charging voltage of the capacitor included in the power supply unit 96.

  Further, a display unit 21 and an input unit 22 are electrically connected to the bus line 19. The display unit 21 is configured using, for example, a liquid crystal display or the like, and displays various information such as processing results and recipe contents. The input unit 22 is configured using, for example, a keyboard, a mouse, and the like, and receives input of commands, parameters, and the like. The operator of the apparatus can input commands and parameters from the input unit 22 while confirming the contents displayed on the display unit 21. Note that the display unit 21 and the input unit 22 may be integrated to form a touch panel.

  Next, the processing operation in the heat treatment apparatus 100 according to the present invention will be described. A semiconductor wafer W to be processed in the heat treatment apparatus 100 is a silicon semiconductor wafer into which impurities (ions) are introduced. Here, after briefly explaining the wafer flow in the entire heat treatment apparatus 100 and the processing contents in the flash heating unit 160, calculation of light energy absorbed by the semiconductor wafer W will be explained.

  In the heat treatment apparatus 100, first, a plurality of semiconductor wafers W after ion implantation are placed on the load port 110 of the indexer unit 101 while being stored in a carrier C. Then, the delivery robot 120 takes out the semiconductor wafers W one by one from the carrier C and carries them into the alignment unit 130. The alignment unit 130 positions the semiconductor wafer W by optically detecting notches and the like by rotating the semiconductor wafer W held on the support pins 136 around the vertical axis around the center portion. In the alignment unit 130, the optical measurement unit 30 measures the spectral intensity of the reflected light from the semiconductor wafer W.

  The semiconductor wafer W positioned by the alignment unit 130 is taken out into the transfer chamber 170 by the transfer arm 151 a on the upper side of the transfer robot 150, and turns so that the transfer robot 150 faces the flash heating unit 160.

  When the transfer robot 150 faces the flash heating unit 160, the lower transfer arm 151b takes out the preceding flash heat-treated semiconductor wafer W from the flash heating unit 160, and the upper transfer arm 151a removes the unprocessed semiconductor wafer W. It is carried into the flash heating unit 160. At this time, the transfer robot 150 slides the transfer arms 151a and 151b perpendicularly to the longitudinal direction of the flash lamp FL.

  Next, the transfer robot 150 turns to face the cooling unit 140, and the lower transfer arm 151 b places the semiconductor wafer W that has been subjected to the flash heat treatment in the cooling unit 140. The semiconductor wafer W cooled by the cooling unit 140 is returned to the carrier C by the delivery robot 120.

  Then, the processing content in the flash heating part 160 is demonstrated. In the flash heating unit 160, activation of impurities introduced into the semiconductor wafer W is executed by flash heating processing.

  First, the holding unit 7 is lowered from the processing position shown in FIG. 7 to the delivery position shown in FIG. The “processing position” is a position of the holding unit 7 when the semiconductor wafer W is irradiated with flash light from the flash lamp FL, and is a 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 in the chamber 6 of the holding unit 7 shown in FIG. The reference position of the holding unit 7 in the flash heating unit 160 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 when the processing is started. As shown in FIG. 3, when the holding unit 7 is lowered to the delivery position, the holding unit 7 comes close to the chamber bottom 62, and the tip of the support pin 70 penetrates the holding unit 7 and protrudes above the holding unit 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 to be processed is transferred into the chamber 6 via the transfer opening 66 by the transfer robot 150 and mounted on the plurality of support pins 70. Placed.

  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 through 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 moves up to the processing position, the semiconductor wafer W placed on 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.

  Preheating for about 60 seconds is performed at this 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 550 ° C., in which impurities added to the semiconductor wafer W are not likely to diffuse due to heat. Further, 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 about 60 seconds elapses, flash light is irradiated from the flash lamp FL of the lamp house 5 toward the semiconductor wafer W under the control of the control unit 3 while the holding unit 7 is positioned at the processing position. At this time, a part of the flash light emitted from the flash lamp FL goes directly to the holding part 7 in the chamber 6, and the other part is once reflected by the reflector 52 and then goes into the chamber 6. Flash heating of the semiconductor wafer W is performed by irradiation of the flash light. Since the flash heating is performed by flash irradiation from the flash lamp FL, the surface temperature of the semiconductor wafer W can be increased in a short time.

  In other words, the flash light emitted from the flash lamp FL of the lamp house 5 is converted to a light pulse whose electrostatic energy stored in advance is extremely short, and the irradiation time is about 0.1 to 100 milliseconds. A short and strong flash. The surface temperature of the semiconductor wafer W flash-heated by flash light irradiation from the flash lamp FL instantaneously rises to a processing temperature T2 of about 1000 ° C. to 1100 ° C., and the impurities implanted into the semiconductor wafer W are activated. After being converted, the surface temperature rapidly decreases. As described above, in the heat treatment apparatus 100, the surface temperature of the semiconductor wafer W can be raised and lowered in a very short time, so that the impurities are activated while suppressing the diffusion of the impurities injected into the semiconductor wafer W due to the heat. Can do. Since the time required for the activation of impurities is extremely short compared to the time required for the thermal diffusion, the activation is possible even in a short time in which diffusion of about 0.1 millisecond to 100 millisecond does not occur. Complete. Further, the light energy absorbed by the semiconductor wafer W during the flash light irradiation is calculated as described below.

  Further, by preheating the semiconductor wafer W by the holding unit 7 before the flash heating, the surface temperature of the semiconductor wafer W can be quickly raised to the processing temperature T2 by the flash light irradiation from the flash lamp FL. .

  After the flash heating is finished and the standby for about 10 seconds at the processing position, the holding unit 7 is lowered again to the delivery position shown in FIG. 3 by the holding unit lifting mechanism 4, and the semiconductor wafer W is transferred from the holding unit 7 to the support pins 70. Is passed. 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 150, and flash heating of the semiconductor wafer W in the flash heating unit 160 is performed. Processing is complete.

  As described above, nitrogen gas is continuously supplied to the chamber 6 during the heat treatment of the semiconductor wafer W in the flash heating unit 160, and the supply amount is about 30 liters / second 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.

  Next, calculation of the light energy absorbed by the semiconductor wafer W when the flash light is irradiated will be described. FIG. 11 is a flowchart showing a calculation procedure of light energy absorbed by the semiconductor wafer W. First, the spectral intensity of the halogen lamp HL provided in the projector 33 of the alignment unit 130 is acquired (step S11). In this embodiment, the spectral intensity of the halogen lamp HL is acquired using a standard wafer with a known spectral emissivity. As such a standard wafer having a known spectral emissivity, for example, a bare wafer on which no pattern is formed can be used.

  A standard wafer is carried into the alignment unit 130 and placed on the support pins 136. Then, the spectral intensity of the reflected light obtained when the surface of the standard wafer is irradiated with the halogen light from the halogen lamp HL of the projector 33 via the measurement optical system 31 is measured. Specifically, when the standard wafer is supported on the support pins 136, the light emitted from the measurement optical system 31 is irradiated onto the surface of the standard wafer. The reflected light reflected from the surface of the standard wafer is received by the measurement optical system 31 and then subjected to spectral decomposition processing by the spectroscope 35, and the processing result is input to the measurement unit 95. The measuring unit 95 measures the spectral intensity of the reflected light reflected on the surface of the standard wafer based on the signal output from the spectroscope 35.

  FIG. 12 is a diagram showing the spectral intensity of the halogen lamp HL or the like. FIG. 12 also shows the spectral intensity of the reflected light of the standard wafer and the semiconductor wafer W to be processed. The spectral emissivity of a standard wafer (in this embodiment, a bare wafer) is known. Since the transmittance of the silicon wafer can be regarded as 0 in the visible light region having a wavelength of 400 nm to 800 nm, the relationship that the sum of the emissivity and the reflectance is 1 is satisfied. Therefore, if the spectral emissivity of the standard wafer is known, the spectral reflectance is also known.

  The spectral intensity of the reflected light of the standard wafer shown in FIG. 12 is an actual measurement result measured by the alignment unit 130 as described above. The spectral intensity of the halogen lamp HL shown in FIG. 12 can be obtained by dividing the spectral intensity of the reflected light of the standard wafer by the spectral reflectance of the standard wafer. In this case, calculation is performed for each wavelength within a range of 400 nm to 800 nm. For example, the intensity of 500 nm of the halogen lamp HL is obtained by dividing the intensity of reflected light of 500 nm by the reflectance of 500 nm. It is done.

  Such acquisition of the spectral intensity of the halogen lamp HL does not have to be performed every time the semiconductor wafer W to be processed is processed. For example, the spectral intensity acquired during maintenance of the heat treatment apparatus 100 is used as the magnetic disk of the control unit 3. It may be stored at 14 mag. In this embodiment, the spectral intensity of the halogen lamp HL is acquired using a standard wafer. However, the present invention is not limited to this. For example, instead of the standard wafer, an ideal mirror wafer having a reflectance of almost 100% ( For example, you may make it use an aluminum vapor deposition wafer etc.). Alternatively, the spectral decomposition processing may be performed by directly receiving the light emitted from the halogen lamp HL.

  Next, the semiconductor wafer W to be processed is carried into the alignment unit 130 (step S12). This is the loading of the semiconductor wafer W into the alignment unit 130 for positioning in the wafer flow of the entire heat treatment apparatus 100 described above. The alignment unit 130 positions (adjusts the orientation of) the semiconductor wafer W to be processed and measures the spectral intensity of the reflected light from the semiconductor wafer W (step S13). Specifically, the semiconductor wafer W carried into the alignment unit 130 is placed on the support pins 136. The semiconductor wafer W supported by the support pins 136 is rotated and positioned. Further, by supporting the semiconductor wafer W on the support pins 136, the surface of the semiconductor wafer W is irradiated with halogen light emitted from the halogen lamp HL of the projector 33 through the measurement optical system 31. Then, the reflected light reflected by the surface of the semiconductor wafer W to be processed is received by the measurement optical system 31 and then subjected to spectral decomposition processing by the spectroscope 35, and the processing result is input to the measurement unit 95. Is done. The measuring unit 95 measures the spectral intensity of the reflected light reflected from the surface of the semiconductor wafer W to be processed based on the signal output from the spectroscope 35. The measurement result by the measurement unit 95 is transmitted to the control unit 3 and stored in the magnetic disk 14 or the like.

  The spectral intensity of the reflected light of the wafer to be processed shown in FIG. 12 is the spectral intensity of the reflected light of the semiconductor wafer W obtained as described above. The standard wafer of this embodiment is a bare wafer, and the reflectance of a bare wafer that is not patterned is different from the reflectance of a semiconductor wafer W to be processed on which a pattern is formed. In general, the reflectivity of the patterned semiconductor wafer W to be processed is lower than the reflectivity of the bare wafer (that is, the emissivity of the semiconductor wafer W to be processed is higher). For this reason, as shown in FIG. 12, the spectral intensity of the reflected light of the semiconductor wafer W to be processed is generally lower than the spectral intensity of the reflected light of the standard wafer.

  Next, the spectral emissivity of the semiconductor wafer W to be processed is calculated (step S14). In this process, the control unit 3 determines the spectral emissivity of the semiconductor wafer W to be processed from the spectral intensity of the halogen lamp HL acquired in step S11 and the spectral intensity of the reflected light of the semiconductor wafer W to be processed actually measured in step S13. Calculate. Specifically, the spectral reflectance of the semiconductor wafer W to be processed is divided by dividing the spectral intensity of the reflected light of the semiconductor wafer W to be processed stored in the magnetic disk 14 or the like by the spectral intensity of the halogen lamp HL. Calculated. This calculation is divided for each wavelength within a range of 400 nm to 800 nm. Then, by subtracting the spectral reflectance from 1, the spectral emissivity of the semiconductor wafer W to be processed is calculated.

  FIG. 13 is a diagram showing the spectral emissivity of the semiconductor wafer W to be processed. FIG. 13 also shows the spectral emissivity of the standard wafer. As mentioned above, the spectral emissivity of a standard wafer is known. The spectral emissivity of the patterned semiconductor wafer W is generally higher than that of the standard wafer. The calculated spectral emissivity of the processing target semiconductor wafer W shown in FIG. 13 is stored in the magnetic disk 14 or the like.

  Next, the light energy absorbed by the semiconductor wafer W to be processed at the time of flash light irradiation is calculated (step S15). This calculation is performed by the control unit 3 executing the calculation of the following equation (1).

  In Equation (1), E is the light energy to be obtained, and λ is the wavelength. I (λ) is the intensity at the wavelength λ of the flash light emitted from the flash lamp FL, and ε (λ) is the emissivity (absorption rate) at the wavelength λ of the semiconductor wafer W to be processed. . That is, Expression (1) is obtained by integrating the intensity of the flash light irradiated from the flash lamp FL by the emissivity of the semiconductor wafer W in the range from the wavelength λ1 to the wavelength λ2.

  FIG. 14 shows the spectral intensity of the flash light emitted from the flash lamp FL. The spectral intensity of the flash light varies depending on the gas pressure of the flash lamp FL and the like, and if the flash lamp FL of the same standard emits light under the same conditions (the same applied voltage), the spectral intensity is also the same. Generally, the spectral characteristic of the intensity of the flash lamp FL is shifted to the shorter wavelength side than the spectral characteristic of the intensity of the halogen lamp HL shown in FIG. Such a spectral intensity I (λ) of the flash lamp FL is acquired in advance and stored in the magnetic disk 14 or the like of the control unit 3. On the other hand, the emissivity for each wavelength of the semiconductor wafer W to be processed, that is, the spectral emissivity ε (λ) is obtained as described above (FIG. 13). The light energy E absorbed by the semiconductor wafer W during the flash light irradiation from the flash lamp FL is calculated by integrating the value obtained by multiplying these values in the range of the wavelength λ1 = 400 nm to the wavelength λ2 = 800 nm.

  In the first embodiment, the spectral intensity of the halogen lamp HL and the spectral intensity of the reflected light obtained by irradiating the surface of the semiconductor wafer W to be processed from the halogen lamp HL with the halogen light are measured. Spectral emissivity is calculated. Based on the spectral emissivity of the semiconductor wafer W to be processed and the spectral intensity of the flash lamp FL, the light absorbed by the semiconductor wafer W when the flash light is irradiated onto the surface of the semiconductor wafer W from the flash lamp FL. Energy E is calculated. That is, the difference between the spectral distribution of the intensity of the halogen lamp HL used for the reflected light intensity measurement and the spectral distribution of the intensity of the flash lamp FL used for the heat treatment is taken into consideration, and the spectral characteristic of the emissivity of the semiconductor wafer W is also taken into consideration. Therefore, the light energy E absorbed by the semiconductor wafer W at the time of flash light irradiation can be accurately calculated.

<2. Second Embodiment>
Next, a second embodiment of the present invention will be described. The configuration of the heat treatment apparatus of the second embodiment is exactly the same as that of the first embodiment. The wafer flow in the entire heat treatment apparatus of the second embodiment and the processing content in the flash heating unit are also the same as those in the first embodiment. In the second embodiment, the light energy absorbed by the semiconductor wafer W during flash light irradiation is obtained, and the temperature at which the surface of the semiconductor wafer W reaches during flash light irradiation is calculated.

  FIG. 15 is a flowchart showing a procedure for calculating the surface temperature of the semiconductor wafer W. In FIG. 15, Steps S21 to S25 are exactly the same as Steps S11 to S15 of FIG. 11 of the first embodiment. That is, the spectral emissivity of the semiconductor wafer W is calculated from the spectral intensity of the halogen lamp HL and the spectral intensity of the reflected light obtained by irradiating the surface of the semiconductor wafer W to be processed from the halogen lamp HL. To do. Based on the spectral emissivity of the semiconductor wafer W to be processed and the spectral intensity of the flash lamp FL, the light absorbed by the semiconductor wafer W when the flash light is irradiated onto the surface of the semiconductor wafer W from the flash lamp FL. Calculate energy.

  In the second embodiment, the temperature at which the surface of the semiconductor wafer W reaches during flash light irradiation is calculated based on the light energy absorbed by the semiconductor wafer W (step S26). This calculation is based on the light energy absorbed by the semiconductor wafer W at the time of flash light irradiation and the density, specific heat, and thermal conductivity (which are already known) of the semiconductor wafer W, for example, a known unsteady heat conduction analysis method. Can be used.

  In the second embodiment, the surface temperature of the semiconductor wafer W at the time of flash light irradiation can be accurately calculated based on the absorbed light energy of the semiconductor wafer W accurately obtained in consideration of spectral characteristics. Since it is difficult to directly measure the surface temperature of the semiconductor wafer W by flash heating with an extremely short irradiation time, the technical significance of calculating the surface temperature at the time of flash light irradiation as in the second embodiment is great. .

<3. Third Embodiment>
Next, a third embodiment of the present invention will be described. The configuration of the heat treatment apparatus of the third embodiment is exactly the same as that of the first embodiment. The wafer flow in the entire heat treatment apparatus of the third embodiment and the processing contents in the flash heating unit are also the same as those in the first embodiment. In the third embodiment, the light energy absorbed by the semiconductor wafer W at the time of flash light irradiation is obtained, and the spectral intensity of the flash light at the time of flash light irradiation is determined.

  FIG. 16 is a flowchart showing a procedure for calculating the spectral intensity of flash light. In FIG. 16, Steps S31 to S35 are exactly the same as Steps S11 to S15 of FIG. 11 of the first embodiment. That is, the spectral emissivity of the semiconductor wafer W is calculated from the spectral intensity of the halogen lamp HL and the spectral intensity of the reflected light obtained by irradiating the surface of the semiconductor wafer W to be processed from the halogen lamp HL. To do. Based on the spectral emissivity of the semiconductor wafer W to be processed and the spectral intensity of the flash lamp FL, the light absorbed by the semiconductor wafer W when the flash light is irradiated onto the surface of the semiconductor wafer W from the flash lamp FL. Calculate energy.

  In the third embodiment, next, the spectral emissivity of the standard wafer is acquired (step S36). As described above, when the standard wafer is a bare wafer, the spectral emissivity of the standard wafer is already known and stored in the magnetic disk 14 or the like and already acquired. However, when a wafer different from the bare wafer is used as the standard wafer, the spectral emissivity of the standard wafer is acquired by the same method as that used to calculate the spectral emissivity of the semiconductor wafer W in the first embodiment.

  For a standard wafer, the correlation between the spectral intensity of the flash lamp FL and the processing result when the flash light having the spectral intensity is irradiated is known. Therefore, for the standard wafer, the spectral intensity of the flash lamp FL that provides the optimum processing result is also known. The processing result here is, for example, the degree of activation of impurities introduced into the wafer, and is specifically defined by the sheet resistance value. Such correlation may be obtained in advance by an experiment or simulation using a standard wafer.

  Next, the light energy absorbed by the standard wafer at the time of flash light irradiation is calculated (step S37). This calculation is performed by the control unit 3 executing the calculation of Expression (1), as in the first embodiment. However, ε (λ) used in the calculation of step S37 is the emissivity at the wavelength λ of the standard wafer. Further, the spectral intensity I (λ) of the flash lamp FL used in this calculation is the same as the spectral intensity used when calculating the light energy absorbed by the processing target semiconductor wafer W in step S35.

  Next, the light energy absorption ratio r of the semiconductor wafer W to be processed with respect to the standard wafer is calculated (step S38). This calculation is performed by the control unit 3 executing the calculation of the following equation (2).

  In Equation (2), Ep is the light energy absorbed by the semiconductor wafer W to be processed at the time of flash light irradiation obtained at step S35, and Es is absorbed by the standard wafer at the time of flash light irradiation obtained at step S37. Light energy. As shown in FIG. 13, in general, since the emissivity of the semiconductor wafer W to be processed is higher than the emissivity of the standard wafer, Ep> Es, and the optical energy absorption of the semiconductor wafer W to be processed with respect to the standard wafer. The ratio r is greater than 1.

  Next, the spectral intensity of the flash light irradiated on the semiconductor wafer W to be processed is determined based on the correlation and the light energy absorption ratio r described above (step S39). As described above, with respect to the standard wafer, the correlation between the spectral intensity of the flash lamp FL and the processing result when the flash light having the spectral intensity is irradiated is known, and the flash lamp FL capable of obtaining the optimal processing result. The spectral intensity of is also known. In step S39, the control unit 3 obtains an optimum processing result for the semiconductor wafer W to be processed by dividing the spectral intensity of the flash lamp FL from which the optimum processing result is obtained for the standard wafer by the light energy absorption ratio r. The spectral intensity of the flash lamp FL is determined. In general, since the light energy absorption ratio r is larger than 1, it is smaller for the semiconductor wafer W to be processed than the spectral intensity of the flash lamp FL that can obtain the optimum processing result for the standard wafer.

  In the third embodiment, when the spectral intensity of the flash light applied to the semiconductor wafer W to be processed is determined in step S39, the semiconductor wafer W is carried into the flash heating unit 160 to perform flash heat processing. The control unit 3 controls the power supply unit 96 so that the flash lamp FL emits light with the calculated spectral intensity. Specifically, the control unit 3 adjusts the charging voltage (applied voltage) of the capacitor included in the power supply unit 96.

  In the third embodiment, a light energy absorption ratio r is calculated based on the absorbed light energy of the semiconductor wafer W and the standard wafer accurately obtained in consideration of the spectral characteristics, and the semiconductor wafer W to be processed is irradiated. It is possible to accurately determine the spectral intensity of the flash light. The control unit 3 controls the power supply unit 96 so that the flash lamp FL emits light with the spectral intensity, so that the semiconductor wafer W can be heated with the optimum flash light intensity.

<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, in each of the above embodiments, the optical measurement unit 30 is provided in the alignment unit 130 to measure the reflected light intensity of the semiconductor wafer W. However, the optical measurement unit 30 is changed from the indexer unit 101 to the flash heating unit 160. What is necessary is just to install in any position on the path | route which conveys the semiconductor wafer W.

  In each of the above embodiments, 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 may be arbitrary. The flash lamp FL is not limited to a xenon flash lamp, and may be a krypton flash lamp.

  In the above embodiment, the hot plate 71 is used as the assist heating means. However, a plurality of lamp groups (for example, a plurality of halogen lamps) are provided below the holding unit 7 that holds the semiconductor wafer W, and from there Assist heating may be performed by light irradiation.

  Further, 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 or a solar cell substrate used for a liquid crystal display device or the like. Further, the technique according to the present invention may be applied to bonding of metal and silicon or crystallization of polysilicon.

3 Control unit 11 CPU
DESCRIPTION OF SYMBOLS 30 Optical measurement unit 31 Measurement optical system 33 Projector 35 Spectrometer 95 Measurement part 96 Power supply unit 100 Heat processing apparatus 101 Indexer part 120 Delivery robot 130 Alignment part 140 Cooling part 150 Transport robot 160 Flash heating part FL Flash lamp HL Halogen lamp W Semiconductor wafer

Claims (6)

A heat treatment method for heating a processing target substrate by irradiating the processing target substrate with flash light,
(a) obtaining the spectral intensity of the halogen lamp;
(b) measuring the spectral intensity of the reflected light obtained by irradiating the surface of the substrate to be treated from the halogen lamp with halogen light;
(c) calculating the spectral emissivity of the substrate to be processed from the spectral intensity of the halogen lamp obtained in the step (a) and the spectral intensity of the reflected light obtained in the step (b); ,
(d) Based on the spectral emissivity of the substrate to be processed and the spectral intensity of the flash lamp, the light energy absorbed by the substrate to be processed when flash light is irradiated from the flash lamp onto the surface of the substrate to be processed. The process of calculating,
A heat treatment method comprising: The heat treatment method according to claim 1,
(e) The heat treatment further comprising a step of calculating a temperature at which the surface of the substrate to be processed reaches at the time of flash light irradiation from the light energy absorbed by the substrate to be processed obtained in the step (d) Method. In the heat processing method of Claim 1 or Claim 2,
(f) obtaining a spectral emissivity of a standard substrate having a known correlation between a spectral intensity of the flash lamp and a processing result when the flash light having the spectral intensity is irradiated;
(g) Based on the spectral emissivity of the standard substrate and the spectral intensity of the flash lamp, the light energy absorbed by the standard substrate when flash light is irradiated from the flash lamp onto the surface of the standard substrate is calculated. Process,
(h) A step of calculating a light energy absorption ratio of the processing target substrate with respect to the standard substrate based on the calculation result obtained in the step (d) and the calculation result obtained in the step (g). When,
(i) determining a spectral intensity of flash light irradiated to the substrate to be processed based on the correlation and the light energy absorption ratio;
The heat processing method characterized by further providing. A heat treatment apparatus for heating a processing target substrate by irradiating the processing target substrate with flash light,
A halogen lamp that emits halogen light;
A flash lamp that emits flash light;
A reflected light intensity measuring unit that measures the spectral intensity of the reflected light obtained by irradiating the surface of the substrate to be processed from the halogen lamp with halogen light;
The spectral emissivity of the substrate to be processed is calculated from the spectral intensity of the halogen lamp and the spectral intensity of the reflected light. Based on the spectral intensity of the flash lamp and the spectral emissivity, the processing target is calculated from the flash lamp. An absorbed energy calculating unit that calculates light energy absorbed by the substrate to be processed when flash light is irradiated on the surface of the substrate;
A heat treatment apparatus comprising: The heat treatment apparatus according to claim 4, wherein
A heat treatment apparatus, further comprising: a temperature calculation unit that calculates a temperature that the surface of the substrate to be processed reaches at the time of flash light irradiation from light energy absorbed by the substrate to be processed calculated by the absorption energy calculation unit . In the heat treatment apparatus according to claim 4 or 5,
The correlation between the spectral intensity of the flash lamp and the processing result when the standard substrate is irradiated with flash light of the spectral intensity is known,
The absorption energy calculating unit absorbs light that the standard substrate absorbs when flash light is irradiated from the flash lamp onto the surface of the standard substrate based on the spectral emissivity of the standard substrate and the spectral intensity of the flash lamp. Calculate energy,
A light energy absorption ratio of the processing target substrate with respect to the standard substrate when flash light is irradiated from the flash lamp is calculated, and the processing target substrate is irradiated based on the correlation and the light energy absorption ratio. A flash light intensity determination unit that determines the spectral intensity of the flash light;
A heat treatment apparatus comprising:

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