JP5483710B2 - Applied voltage setting method, heat treatment method and heat treatment apparatus - Google Patents

Description

  The present invention relates to an applied voltage for setting an applied voltage to a flash lamp that irradiates and heats a thin plate-like precision electronic substrate (hereinafter simply referred to as “substrate”) such as a semiconductor wafer or a glass substrate for a liquid crystal display device. The present invention relates to a setting method, and a heat treatment method and a heat treatment apparatus for performing heat treatment of a substrate by irradiating flash light from a flash lamp with the applied voltage.

  In recent years, in an impurity (ion) activation process of a semiconductor wafer after ion implantation, it is required to suppress the diffusion of impurities and make the junction depth shallower as the pattern of a semiconductor device becomes finer. As a technology that satisfies these requirements, a xenon flash lamp (hereinafter simply referred to as “flash lamp” means xenon flash lamp) is used to irradiate the surface of a semiconductor wafer with flash light (flash) for a very short time. Flash lamp annealing (FLA) is attracting attention.

  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 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. Therefore, in flash lamp annealing, the surface of a semiconductor wafer into which ions are implanted is irradiated with flash light, and only the surface of the semiconductor wafer is heated to 1000 ° C. or higher in a very short time (several milliseconds or less). it can. As a result, only impurity activation can be performed without deeply diffusing the impurities.

  However, in flash lamp annealing, 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, ion activation cannot be performed. Therefore, it is important to optimize the energy range of the flash light 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 energy of flash light 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. Usually, even when light of the same energy is irradiated, a patterned wafer has a higher emissivity than a bare wafer and tends to absorb a large amount of light energy. 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 problems, Patent Document 1 discloses a standard wafer with a known reflectance, a plain wafer without pattern formation (for example, a bare wafer), and actual processing prior to flash heating. The reflected light intensity of the target semiconductor wafer is measured to calculate the flash energy absorbed by the plain wafer and the flash energy absorbed by the target wafer. Based on these, the flash energy absorption ratio of the target wafer to the plain wafer is calculated. However, a technique for calculating an appropriate energy value to be applied to the wafer to be processed from the value and the appropriate energy value of the flash light applied to the plain wafer is disclosed.

  On the other hand, using an insulated gate bipolar transistor (IGBT), the current flowing in the flash lamp is chopper-controlled, and the flash lamp is turned on for a longer time (approximately 10 milliseconds or more) than simply causing the flash lamp to emit light. Techniques for causing light emission are proposed in Patent Documents 2 and 3. By using such a technique, it is possible to freely set the light emission waveform (time profile of light emission intensity) of the flash lamp. As a result, the surface temperature of the semiconductor wafer can be raised and lowered somewhat gently, and better impurity activation and recovery of defects introduced in a layer deeper than the impurity implantation layer can be realized. Even if it is a gradual temperature increase / decrease, it is just a comparison with the ultra-high speed temperature increase / decrease that simply causes the flash lamp to emit light. It is warm.

JP-A-2005-39213 JP 2009-070948 A JP 2009-099758 A

  Although the appropriate energy value to be applied to the wafer to be processed can be calculated by the technique disclosed in Patent Document 1, the flash energy depends on the voltage applied to the both end electrodes of the flash lamp and the light emission waveform. Therefore, the actual flash energy is adjusted by adjusting the charging voltage of the capacitor that supplies power to the flash lamp.

  Conventionally, the correspondence between the flash energy of flash light emitted from a flash lamp and the voltage applied to the flash lamp has been obtained using a calorimeter. The calorimeter measures the energy of the absorbed light. Since the calorimeter was installed in the chamber at the time of initial setup and maintenance of the device, the charging voltage of the capacitor was changed and flash light irradiation was performed several times to obtain the correspondence between flash energy and applied voltage. is there.

  If the flash lamp is simply made to emit light, the light emission waveform is single. Therefore, once the correspondence between the flash energy and the applied voltage to the flash lamp is obtained by the method described above, based on that, The charging voltage to the capacitor can be adjusted to achieve the desired flash energy.

  However, when the emission waveform of the flash lamp is set freely using the techniques disclosed in Patent Documents 2 and 3, a calorimeter is installed in the chamber each time a new emission waveform is set. The above measurement is required. The calorimeter is installed in the chamber only at the time of measuring flash energy, and the operation of installing the calorimeter by opening the chamber is complicated. In addition, once the chamber is opened and measurement is performed, a contamination check in the chamber is required. For this reason, every time a new light emission waveform is set, there is a problem that the work for obtaining the correspondence between the flash energy and the voltage applied to the flash lamp using a calorimeter becomes very heavy.

  The present invention has been made in view of the above problems, and an object thereof is to provide an applied voltage setting method, a heat treatment method, and a heat treatment apparatus capable of easily setting an applied voltage to a flash lamp.

In order to solve the above-described problem, the invention of claim 1 is an applied voltage setting method for setting an applied voltage to a flash lamp that heats a substrate by irradiating flash light, and causes the flash lamp to emit light at a plurality of applied voltages. An energy measuring step for measuring flash energy of flash light emitted from a flash lamp for each of the plurality of applied voltages, and an applied voltage to the flash lamp and the flash lamp based on a measurement result obtained in the energy measuring step A correlation acquisition step of acquiring a relational expression indicating a correlation with flash energy of flash light emitted from the substrate, and measuring reflected light intensity of the processing target substrate, and emissivity of the standard substrate and processing substrate Acquired in the emissivity ratio calculation process to calculate the emissivity ratio of the above and the correlation acquisition process Based on the relational expression indicating the correlation between the applied voltage and the flash energy and the emissivity ratio between the standard substrate and the substrate to be processed calculated in the emissivity ratio calculation step, the standard substrate absorbs, etc. An applied voltage calculating step for calculating an applied voltage required to absorb the amount of flash energy in the substrate to be processed , wherein the energy measuring step is performed at a plurality of applied voltages for each emission waveform of the flash lamp. the emit light to measure the flash energy, the correlation acquisition process is characterized by the acquired child a relational expression indicating a correlation between the applied voltage and flash energy for each emission waveform of the flash lamp.

According to a second aspect of the present invention, there is provided a heat treatment method for heating a substrate by irradiating the substrate with flash light, a waveform setting step for setting a light emission waveform of the flash lamp , and a flash lamp with a plurality of applied voltages. And measuring the flash energy of the flash light emitted from the flash lamp for each of the plurality of applied voltages, and applying to the flash lamp based on the measurement result obtained in the energy measuring step A correlation acquisition process for acquiring a relational expression indicating a correlation between the voltage and the flash energy of flash light emitted from the flash lamp, and the reflected light intensity of the target substrate is measured, and the emissivity of the standard substrate and the target substrate Emissivity ratio calculation process for calculating the emissivity ratio with the emissivity of the above, and obtaining the correlation The standard substrate absorbs based on the relational expression indicating the correlation between the applied voltage and the flash energy acquired in the step and the emissivity ratio between the standard substrate and the substrate to be processed calculated in the emissivity ratio calculation step. Charging the capacitor with the applied voltage calculated in the applied voltage calculating step, the applied voltage calculating step for calculating the applied voltage required to absorb the same amount of flash energy as the processing target substrate, and And a flash light irradiation step of irradiating the processing target substrate with flash light by supplying power from the capacitor to the flash lamp, and the energy measurement step is performed for each emission waveform of the flash lamp set in the waveform setting step. The flash lamp is caused to emit light at a plurality of applied voltages and the flash energy is measured. And obtaining a relational expression representing a correlation between the applied voltage and flash energy for each emission waveform.

According to a third aspect of the present invention, in the heat treatment method according to the second aspect of the invention, the emissivity ratio calculating step and the applied voltage calculating step are executed for each substrate to be processed.

According to a fourth aspect of the present invention, in the heat treatment method according to the second or third aspect of the present invention, the emissivity ratio calculating step includes a standard substrate, a target substrate, and a substrate to be processed within a light emission wavelength range of a flash lamp. It is characterized by calculating the emissivity ratio.

According to a fifth aspect of the present invention, in the heat treatment apparatus for heating the substrate by irradiating the substrate with flash light, the substrate is held by the holding unit and the substrate held by the holding unit is irradiated with the flash light. A flash lamp, a capacitor that supplies power to the flash lamp, and a flash lamp that emits light by supplying power from a capacitor that is charged with a plurality of applied voltages, and each of the plurality of applied voltages is irradiated from the flash lamp. And a correlation between an applied voltage to the flash lamp and flash energy of the flash light emitted from the flash lamp based on a measurement result obtained by the energy measuring means. Correlation to obtain a relational expression indicating An acquisition means, a reflected light intensity measuring means for measuring the reflected light intensity of the substrate to be processed, and an emissivity of the standard substrate and an emissivity of the substrate to be processed based on the measurement result obtained by the reflected light intensity measuring means. An emissivity ratio calculating means for calculating an emissivity ratio, a relational expression showing a correlation between an applied voltage acquired by the correlation acquiring means and flash energy, and a standard substrate and processing calculated by the emissivity ratio calculating means Based on the emissivity ratio with the target substrate, an applied voltage calculation means for calculating an applied voltage required for the processing target substrate to absorb the same amount of flash energy as the standard substrate absorbs, and the applied voltage calculation means The processing object held in the holding means by charging the capacitor with the applied voltage calculated by the above and supplying power to the flash lamp from the capacitor. And control means for irradiating a flash light to the plate, and a waveform setting means for setting a light emission waveform of the flash lamp, the energy measurement means, for each emission waveform of the flash lamp set by the waveform setting unit, The flash energy when the flash lamp emits light with a capacitor charged with a plurality of applied voltages is measured, and the correlation acquisition means is a relationship showing the correlation between the applied voltage and the flash energy for each light emission waveform of the flash lamp. It is characterized by acquiring an expression .

According to a sixth aspect of the present invention, in the heat treatment apparatus according to the fifth aspect of the invention, the reflected light intensity measuring means measures the reflected light intensity for each substrate to be processed.

The invention of claim 7 is the heat treatment apparatus according to claim 5 or 6 , wherein the emissivity ratio calculating means includes a standard substrate, a substrate to be processed, and a substrate to be processed within the emission wavelength range of the flash lamp. It is characterized by calculating the emissivity ratio.

According to the first aspect of the invention, the energy measuring step of causing the flash lamp to emit light at a plurality of applied voltages and measuring the flash energy of the flash light emitted from the flash lamp for each of the plurality of applied voltages, and the measurement results Based on the correlation acquisition step of acquiring a relational expression showing the correlation between the voltage applied to the flash lamp and the flash energy of the flash light emitted from the flash lamp, and the reflected light intensity of the substrate to be processed is measured, and the standard An emissivity ratio calculation step for calculating an emissivity ratio between the emissivity of the substrate and the emissivity of the substrate to be processed, a relational expression indicating a correlation between the applied voltage and the flash energy, and emissivity between the standard substrate and the substrate to be processed Based on the ratio, the target substrate can absorb the same amount of flash energy as the standard substrate absorbs. To provide the applied voltage calculation step of calculating the principal application voltage, and the voltage applied to the flash lamp without performing a complicated work such as installing a calorimeter can be set easily.

According to the invention of claim 1 , the flash energy is measured by causing the flash lamp to emit light at a plurality of applied voltages for each light emission waveform of the flash lamp, and the applied voltage and the flash energy are measured for each light emission waveform of the flash lamp. Since the relational expression indicating the correlation is acquired, the applied voltage to the flash lamp can be easily set even when the light emission waveform is changed.

According to the invention of claim 2 to claim 4 , the flash lamp emits light at a plurality of applied voltages, and energy measurement for measuring flash energy of flash light emitted from the flash lamp for each of the plurality of applied voltages. A correlation obtaining step for obtaining a relational expression indicating a correlation between a voltage applied to the flash lamp and a flash energy of the flash light emitted from the flash lamp based on the measurement result, and a reflected light of the processing target substrate An emissivity ratio calculation process for measuring the emissivity ratio between the emissivity of the standard substrate and the emissivity of the substrate to be processed, a relational expression indicating the correlation between the applied voltage and flash energy, and the standard substrate and processing Based on the emissivity ratio with the target substrate, the same amount of flash energy is absorbed as the standard substrate absorbs. The applied voltage calculation process for calculating the applied voltage necessary for absorption into the capacitor, charging the capacitor with the calculated applied voltage, supplying power to the flash lamp from the capacitor, and irradiating the processing target substrate with flash light Therefore, the flash heating process can be performed by simply setting the voltage applied to the flash lamp without performing a complicated operation such as installing a calorimeter.

According to the second to fourth aspects of the present invention, the method further comprises a waveform setting step for setting a light emission waveform of the flash lamp, and the flash lamp is caused to emit light at a plurality of applied voltages for each light emission waveform of the flash lamp. Since energy is measured and a relational expression indicating the correlation between the applied voltage and flash energy is obtained for each flash lamp emission waveform, the applied voltage to the flash lamp can be easily set even when the emission waveform is changed. it can.

According to the invention of claim 5 to claim 7 , holding means for holding the substrate, a flash lamp for irradiating flash light to the substrate held by the holding means, a capacitor for supplying power to the flash lamp, An energy measuring means for measuring flash energy of flash light emitted from the flash lamp for each of the plurality of applied voltages when the flash lamp emits light by supplying power from a capacitor charged with the plurality of applied voltages; and Correlation acquisition means for acquiring a relational expression indicating the correlation between the voltage applied to the flash lamp and the flash energy of the flash light emitted from the flash lamp based on the measurement result, and the reflected light intensity of the substrate to be processed is measured Reflected light intensity measurement means and standard board radiation based on the measurement result Based on the emissivity ratio calculation means for calculating the emissivity ratio between the emissivity and the substrate to be processed, the relational expression indicating the correlation between the applied voltage and the flash energy, and the emissivity ratio between the standard substrate and the substrate to be processed The applied voltage calculation means for calculating the applied voltage required to absorb the same amount of flash energy as the standard substrate absorbs, and the capacitor is charged with the calculated applied voltage. And control means for irradiating the processing target substrate held by the holding means with flash light by supplying power to the flash lamp, so that the flash lamp can be operated without performing complicated work such as installing a calorimeter. The flash heating process can be performed by simply setting the applied voltage.

According to the invention of claim 5 to claim 7 , further comprising waveform setting means for setting a light emission waveform of the flash lamp, and each of the light emission waveforms of the flash lamp is flashed by a capacitor charged with a plurality of applied voltages. The flash energy when the lamp emits light is measured, and the relational expression indicating the correlation between the applied voltage and flash energy is obtained for each flash lamp emission waveform, so the applied voltage to the flash lamp is also changed when the emission waveform is changed. Can be set easily.

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 longitudinal cross-sectional view which shows the structure of the flash heating part of FIG. It is a figure which shows the drive circuit of a flash lamp. 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 figure which shows the hardware constitutions of a control part. It is a functional block diagram of a control part. It is a flowchart which shows the setting procedure of the applied voltage with respect to a flash lamp. It is a figure which shows the example of the light emission waveform of a flash lamp. It is a figure which shows an example of the linear approximation of the relationship between an applied voltage and flash energy. It is a figure which shows the spectral characteristic of the reflected light intensity of the semiconductor wafer used as a process target, and a standard wafer.

  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 configuration>
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. The heat treatment apparatus 100 is a flash lamp annealing apparatus that irradiates a substantially circular semiconductor wafer W as a substrate with flash light and heats the semiconductor wafer W. 1 and FIG. 2 are partially sectional views as appropriate, and details are simplified as appropriate. 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 and unloading the processed semiconductor wafer W outside the apparatus, and an unprocessed semiconductor. Alignment unit 130 for positioning wafer W, cooling unit 140 for cooling semiconductor wafer W after the heat treatment, flash heating unit 160 for performing flash heat treatment on semiconductor wafer W, alignment unit 130, cooling unit 140, and flash heating unit A transport robot 150 that transports a semiconductor wafer W to 160 is provided. Further, the heat treatment apparatus 100 includes a control unit 3 that controls the operation mechanism and the transfer robot 150 provided in each processing unit described above to advance the flash heating process of 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) or the like and placed on the load port 110, and the carrier C containing the processed semiconductor wafer W is transported by the automatic guided vehicle. It 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. As a result, the delivery robot 120 carries the semiconductor wafer W in and out of the two carriers C, and delivers 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 wafer center is located at a predetermined position. The alignment unit 130 positions the semiconductor wafer W by optically detecting notches, orientation flats, and the like by rotating about the central axis of the semiconductor wafer W received from the indexer unit 101 around the vertical axis. The alignment unit 130 includes an optical measurement unit described later, and the reflected light intensity of the semiconductor wafer W to be processed is measured by the optical measurement unit.

  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 flash light (flash light) from the xenon flash lamp FL onto the pre-heated semiconductor wafer W. The configurations of the flash heating unit 160 and the alignment unit 130 will be further described 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 including a plurality of arm segments. 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 accommodates the transfer robot 150 is provided as a transfer space of 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. It turns and then moves up and down (or while it is turning) so that one of the transfer arms is positioned at a height at which the semiconductor wafer W is delivered to the delivery 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. Note that these gate valves are appropriately opened and closed when the semiconductor wafer W is transported.

  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.

<1-2. Configuration of flash heating unit>
Next, the configuration of the flash heating unit 160 will be described in detail. FIG. 3 is a longitudinal sectional view showing the configuration of the flash heating unit 160. 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.

  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 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 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.

  Further, the light measuring unit 2 is provided at a portion of the chamber side 63 opposite to the transfer opening 66. The light measurement unit 2 includes a calorimeter 24 and a light derivation structure 20, receives light irradiated into the chamber 6, and sends an electrical signal for calculating the energy to the control unit 3. The light derivation structure 20 includes a first quartz rod 21, a prism 22, and a second quartz rod 23, and guides the light irradiated in the chamber 6 to a calorimeter 24 installed outside the chamber 6.

  The first quartz rod 21 is provided above the gas introduction buffer 83 so as to penetrate the chamber side portion 63 in the horizontal direction. The height position at which the first quartz rod 21 is installed is the same height position as that of the semiconductor wafer W held by the holding unit 7 raised to the processing position described later. The first quartz rod 21 is a quartz rod-shaped member having a diameter of about 10 mm. The tip of the first quartz rod 21 on the heat treatment space 65 side is cut obliquely to form a prism, and the upper side is a flat incident surface.

  A prism 22 is bonded to the base end side of the first quartz rod 21 (outside the chamber 6). Further, a second quartz rod 23 is bonded to the prism 22. The prism 22 is a triangular prism member made of quartz, and the first quartz rod 21 is bonded to one surface forming a right angle, and the second quartz rod 23 is bonded to the other surface. The second quartz rod 23 is also a quartz rod-like member having a diameter of about 10 mm, like the first quartz rod 21. The second quartz rod 23 is provided along the vertical direction, its upper end is bonded to the prism 22, and its lower end is connected to the calorimeter 24.

  The light irradiated from above into the heat treatment space 65 in the chamber 6 is incident on the incident surface of the first quartz rod 21, is reflected by the inclined surface of the tip, and is guided to the proximal end side in the first quartz rod 21. . The light guided through the first quartz rod 21 is totally reflected by the prism 22 and enters the second quartz rod 23. Further, the light guided through the second quartz rod 23 enters the calorimeter 24.

  The calorimeter 24 incorporates a black body (not shown) that absorbs light, and converts heat generated in the black body that has absorbed incident light into an electrical signal such as a voltage. In the present embodiment, the calorimeter 24 sends an electrical signal obtained by converting the heat energy to the control unit 3, and the energy measurement unit 301 (see FIG. 12) of the control unit 3 irradiates the energy of the light irradiated into the chamber 6 ( Strictly speaking, the energy density is calculated.

  Further, the flash heating unit 160 holds the semiconductor wafer W in a horizontal posture inside the chamber 6 and performs a preheating of the semiconductor wafer W held before the flash light irradiation, and a substantially disc-shaped holding unit 7; A holding unit lifting mechanism 4 that lifts and lowers the holding unit 7 with respect to the chamber bottom 62 that 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 includes a light source composed of a plurality of (30 in this embodiment) xenon flash lamps FL inside the housing 51, and a reflector 52 provided so as to cover the light source, It is configured with. 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 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.

  FIG. 8 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 an IGBT (insulated gate bipolar transistor) 96 are connected in series. 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 control unit 3.

  The IGBT 96 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. An IGBT control unit 98 is connected to the gate of the IGBT 96. The IGBT control unit 98 is a circuit that drives the IGBT 96 on and off by applying a pulse signal to the gate of the IGBT 96. The control unit 3 controls the timing at which the IGBT control unit 98 turns the IGBT 96 on and off. Specifically, the waveform setting unit 305 (see FIG. 12) of the control unit 3 sets the waveform of the pulse signal, and the IGBT control unit 98 outputs the pulse signal to the gate of the IGBT 96 according to the waveform. When the IGBT control unit 98 applies a voltage higher than a predetermined value (Hi voltage when the pulse signal is on) to the gate of the IGBT 96, the IGBT 96 is turned on, and a voltage lower than the predetermined value (Low voltage when the pulse signal is off). Is applied, the IGBT 96 is turned off. In this way, the circuit including the flash lamp FL is turned on / off by the IGBT 96.

  Even if the IGBT 96 is turned on while the capacitor 93 is charged and a high voltage is applied to both end electrodes of the glass tube 92, the xenon gas is electrically an insulator, so that the glass is normal in the state. No electricity flows in the 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.

  Further, the reflector 52 in FIG. 3 is provided above the plurality of flash lamps FL so as to cover the whole. 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.

  In addition to the above-described configuration, the flash heating unit 160 performs various cooling operations in order to prevent an excessive increase in temperature of the 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. It has a structure for. 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 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.

<1-3. Configuration of alignment unit>
Next, the configuration of the alignment unit 130 will be described. FIG. 9 is a diagram illustrating a configuration of the alignment unit 130. The alignment unit 130 includes a chamber 131 and a wafer holding unit 132 and an optical measurement unit 230.

  The chamber 131 is a metal housing that houses the semiconductor wafer W. Openings (not shown) for accessing the delivery robot 120 and the transfer robot 150 are provided on the side walls of the chamber 131, and the openings are opened and closed by gate valves 181 and 183.

  A wafer holding part 132 is provided at the bottom of the chamber 131. The wafer holding unit 132 includes a rotary table 133 and an alignment motor 135. The turntable 133 supports and places the semiconductor wafer W from the lower surface. The rotary table 133 can be rotated around the vertical axis by an alignment motor 135.

  The optical measurement unit 230 includes a measurement optical system 231, a projector 233 coupled to the measurement optical system 231 via a light projecting optical fiber 232, and a light receiving optical fiber 234 to the measurement optical system 231. And a spectroscope 235 coupled to each other. Among the constituent elements of the optical measurement unit 230, the measurement optical system 231 is fixedly installed on the ceiling portion of the chamber 131, and the other elements are provided outside the chamber 131. The projector 233 contains a halogen lamp and generates a certain amount of light. The light emitted from the projector 233 is guided to the measurement optical system 231 through the projection optical fiber 232.

  FIG. 10 is a diagram for explaining the configuration of the measurement optical system 231. The measurement optical system 231 functions as a light projecting / receiving unit that irradiates the main surface of the semiconductor wafer W supported by the rotary table 133 with halogen light and receives reflected light from the main surface. In the measurement optical system 231, an achromatic lens 236, a half mirror 237, and a total reflection mirror 238 are arranged along the vertical direction in order from the bottom. Further, a diffuser 239 is disposed along the direction in which the reflected light from the total reflection mirror 238 travels.

  The half mirror 237 is provided in a posture that forms an angle of 45 ° with respect to the semiconductor wafer W supported by the rotary table 133 (an angle of 45 ° with respect to the horizontal plane), and the emission end of the light projecting optical fiber 232. The light in the horizontal direction from 232a is received and reflected downward in the vertical direction. The light reflected by the half mirror 237 passes through the achromatic lens 236 and travels downward. The light emitted downward from the measurement optical system 231 is irradiated onto the main surface of the semiconductor wafer W when the semiconductor wafer W is supported on the rotary table 133.

  The reflected light reflected from the surface of the semiconductor wafer W sequentially passes through the achromatic lens 236 and the half mirror 237 and is reflected toward the diffuser 239 by the total reflection mirror 238. The reflected light that has entered the diffuser 239 undergoes a diffusion uniformization process, and enters the incident end 234 a of the light receiving optical fiber 234.

  In other words, the diffuser 239 is interposed between the incident end 234a of the light receiving optical fiber 234 and the total reflection mirror 238. The incident end surface 239a faces the total reflection mirror 238, and the emission end surface 239b receives light. The optical fiber 234 faces the incident end 234a. The achromatic lens 236 has a function of focusing the reflected light from the semiconductor wafer W onto the incident end surface 239a of the diffuser 239.

  The light incident on the light receiving optical fiber 234 is subjected to spectral decomposition processing by the spectroscope 235, and a signal output from the spectroscope 235 is input to the control unit 3 as a result of this processing. The emissivity ratio calculating unit 303 (see FIG. 12) of the control unit 3 calculates the emissivity between the emissivity of the standard wafer and the emissivity of the semiconductor wafer W to be processed from the reflected light intensity of the semiconductor wafer W as described later. Calculate the ratio.

  In addition to the components described above, the alignment unit 130 includes a detection head for detecting a notch (notch for a φ300 mm wafer, orientation flat for a φ200 mm wafer) of the semiconductor wafer W supported by the rotary table 133 and rotating. A gas supply unit that supplies nitrogen gas to the chamber 131, an exhaust unit that exhausts atmospheric gas in the chamber 131, and the like (both not shown) are provided.

<1-4. Configuration of control unit>
Next, the configuration of the control unit 3 will be described. The control unit 3 controls the various operation mechanisms provided in the heat treatment apparatus 100. FIG. 11 is a diagram illustrating a hardware 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 31 that performs various arithmetic processes, a ROM 32 that is a read-only memory that stores basic programs, a RAM 33 that is a readable / writable memory that stores various information, control software, data, and the like. The magnetic disk 34 to be placed is connected to a bus line 39.

  The bus line 39 includes a motor 40 of the holding unit lifting mechanism 4, a power supply unit 95 that charges the capacitor 93, a trigger circuit 97 that applies a high voltage to the trigger electrode 91, an IGBT control unit 98 that drives the IGBT 96 on and off, an optical unit The projector 233 and spectroscope 235 of the measurement unit 230, the calorimeter 24, and the like are electrically connected. Further, the display unit 35 and the input unit 36 are electrically connected to the bus line 39. The display unit 35 is configured by using, for example, a liquid crystal display and displays various information such as processing results and recipe contents. The input unit 36 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 36 while confirming the contents displayed on the display unit 35. The display unit 35 and the input unit 36 may be integrated to form a touch panel.

  FIG. 12 is a functional block diagram of the control unit 3. The energy measurement unit 301, the correlation acquisition unit 302, the emissivity ratio calculation unit 303, the applied voltage calculation unit 304, and the waveform setting unit 305 provided in the control unit 3 are stored in the magnetic disk 34 by the CPU 31 of the control unit 3. It is a function processing unit realized by executing processing software. The processing contents of these function processing units will be described together with the processing operation of the heat treatment apparatus 100.

<2. Processing operation of heat treatment equipment>
Next, the processing operation of the semiconductor wafer W by 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 semiconductor wafer to which impurities (ions) are added by ion implantation after pattern formation. The activation of the impurities is performed by flash light irradiation heat treatment (annealing) by the flash heating unit 160. Here, after briefly explaining the wafer flow in the heat treatment apparatus 100 as a whole, the application voltage setting to the flash lamp FL and the processing contents in the flash heating unit 160 will be explained. The processing procedure of the heat treatment apparatus 100 described below proceeds by the control unit 3 controlling each operation mechanism of the heat treatment apparatus 100.

<2-1. Wafer flow in the entire heat treatment system>
In the heat treatment apparatus 100, first, a plurality of semiconductor wafers W after impurity implantation are placed on the load port 110 of the indexer unit 101 in a state where a plurality of semiconductor wafers W are accommodated in the carrier C. Then, the delivery robot 120 takes out the semiconductor wafers W one by one from the carrier C and places them on 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 supported on the rotary table 133 around the vertical axis with the central portion as a rotation center. Moreover, the reflected light intensity measurement of the semiconductor wafer W by the optical measurement unit 230 is also performed.

  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 semiconductor wafer W after the flash heating process 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.

  In the flash heating unit 160, the semiconductor wafer W is preheated, and then flash light is irradiated to perform flash heating. At this time, an applied voltage to the flash lamp FL is calculated as described later, and power is supplied to the flash lamp FL from the capacitor 93 charged with the applied voltage to irradiate the semiconductor wafer W with flash light. After the flash heating is completed, the semiconductor wafer W is received and carried out by the lower transfer arm 151b of the transfer robot 150. 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.

<2-2. Setting the emission waveform>
Prior to the description of the applied voltage setting and the flash heating process, the setting of the light emission waveform (light emission intensity time profile) of the flash lamp FL will be described. In the present embodiment, the waveform setting unit 305 of the control unit 3 sets the waveform of the pulse signal, and the IGBT control unit 98 outputs the pulse signal to the gate of the IGBT 96 according to the waveform, whereby the IGBT 96 is on / off controlled. The circuit including the flash lamp FL is turned on and off by the IGBT 96, whereby the light emission waveform of the flash lamp FL is defined.

  Such setting of the light emission waveform of the flash lamp FL is performed by adjusting the waveform of the pulse signal output from the IGBT control unit 98. Specifically, the operator sequentially inputs the pulse width time (ON time) and the pulse interval time (OFF time) of the pulse signal from the input unit 36 to the control unit 3. The waveform setting unit 305 of the control unit 3 sets the waveform of the pulse signal according to the input content. The time of each pulse width and the time of the pulse interval are approximately 0.1 milliseconds to several milliseconds.

  The IGBT control unit 98 outputs a pulse signal to the gate of the IGBT 96 according to the pulse waveform set by the waveform setting unit 305. Thereby, the IGBT 96 is turned on when the pulse signal output from the IGBT controller 98 is on, and the IGBT 96 is turned off when it is off. As a result, the circuit including the flash lamp FL is turned on / off by the IGBT 96.

  Further, the control unit 3 controls the trigger circuit 97 and applies a trigger voltage to the trigger electrode 91 in synchronization with the timing when the IGBT control unit 98 first turns on the IGBT 96. When the charge is accumulated in the capacitor 93 and the IGBT 96 is turned on, and when a high voltage is applied to the trigger electrode 91 in synchronization therewith, the charge accumulated in the capacitor 93 is transferred to the glass tube 92 of the flash lamp FL. A current starts to flow between the electrodes at both ends, and light is emitted by excitation of atoms or molecules of xenon at that time. That is, the flash lamp FL starts to emit light, and the current value flowing through the flash lamp FL increases with time.

  When energization of the flash lamp FL is once started and the IGBT 96 is repeatedly turned on and off intermittently in a state where the current value remains a predetermined value or more, the flash lamp FL is not required to be applied to the trigger electrode 91. Current continues to flow. That is, if a high voltage is applied to the trigger electrode 91 only when the IGBT 96 is first turned on, then the current continues to flow through the flash lamp FL without applying the trigger voltage. When the IGBT 96 is in the on state, the current value flowing in the glass tube 92 of the flash lamp FL increases, and when the IGBT 96 is in the off state, the current value decreases. When the pulse interval time is long or when the current value flowing through the flash lamp FL is low, a high voltage may be applied to the trigger electrode 91 each time the IGBT 96 is turned on. Further, a high voltage may be applied to the trigger electrode 91 at regular time intervals.

  In this way, the current value waveform is defined by the pattern in which the current continues to flow through the flash lamp FL and the IGBT 96 is turned on and off. The emission intensity of the flash lamp FL is substantially proportional to the current flowing through the flash lamp FL. Therefore, the light emission waveform of the flash lamp FL approximates the waveform of the current value flowing through the flash lamp FL.

  When the flash lamp FL is simply caused to emit light without using the IGBT 96 as in the prior art, the charge accumulated in the capacitor 93 is consumed by one light emission, and the output waveform from the flash lamp FL has a width. Becomes a single pulse of about 0.1 to 10 milliseconds. On the other hand, in the present embodiment, the IGBT 96 is connected to the circuit including the flash lamp FL and a pulse signal is output to the gate thereof, whereby the circuit is intermittently turned on and off by the IGBT 96. As a result, the light emission of the flash lamp FL is chopper-controlled, and the electric charge accumulated in the capacitor 93 is divided and consumed, and the flash lamp FL repeats blinking in a very short time. The IGBT 96 is turned on before the current value completely becomes “0”, and the current value increases again. Therefore, the light emission intensity becomes completely “0” even while the flash lamp FL is repeatedly blinking. It is not a thing.

  As described above, the waveform setting unit 305 of the control unit 3 sets the waveform of the pulse signal based on the input content from the input unit 36, and the IGBT control unit 98 outputs the pulse signal to the gate of the IGBT 96 according to the waveform. The IGBT 96 is on / off controlled in accordance with the pulse signal output from the IGBT control unit 98, and the circuit including the flash lamp FL is turned on / off by the IGBT 96, whereby the waveform of the current value flowing through the flash lamp FL is defined. As a result, the flash lamp FL emission waveform is defined. That is, the waveform setting unit 305 directly sets the waveform of the pulse signal output to the gate of the IGBT 96, but indirectly sets the light emission waveform of the flash lamp FL. By appropriately adjusting the pulse width time and the pulse interval time input from the input unit 36, the waveform of the pulse signal output from the IGBT control unit 98 to the gate of the IGBT 96 changes, and the emission waveform of the flash lamp FL is also shown in FIG. Can be freely set as illustrated in FIG.

  FIG. 14 is a diagram illustrating an example of a light emission waveform of the flash lamp FL. FIG. 14A shows a light emission waveform when the flash lamp FL is simply caused to emit light as in the conventional case, and such a light emission waveform is obtained when the IGBT 96 is turned on for a long time. FIG. 14B shows a light emission waveform in which the flash lamp FL emits light at a constant intensity for a while and then emits light so as to draw a light emission peak having the highest reached intensity higher than that intensity. Further, FIG. 14C shows a light emission in which the flash lamp FL emits light at a constant intensity for a while and then emits light so as to draw a light emission peak having a maximum intensity higher than that intensity, and then emits light at a constant intensity for a while. It is a waveform. These are all examples of the emission waveform of the flash lamp FL set by the waveform setting unit 305 in accordance with the input content from the input unit 36, and the purpose of the process (impurity activation, impurity diffusion prevention, wafer crack prevention, Depending on the recovery of defects introduced at the time of impurity implantation, etc.

<2-3. Setting of applied voltage>
FIG. 13 is a flowchart showing a procedure for setting an applied voltage to the flash lamp FL. First, the flash lamp FL is caused to emit light at a plurality of applied voltages for a certain light emission waveform, and the flash energy of the flash light emitted from the flash lamp is measured for each of the plurality of applied voltages (step S1). This measurement operation is preferably performed in a state where the semiconductor wafer W does not exist in the chamber 6 and is performed immediately after a new light emission waveform of the flash lamp FL is set by the waveform setting unit 305 of the control unit 3.

The measurement in step S1 will be described in more detail. The light emission waveform of the flash lamp FL is set in advance by the waveform setting unit 305 of the control unit 3. When the voltage V ₁ is applied to the capacitor 93 by the power supply unit 95, the electric charge corresponding to the applied voltage V ₁ is charged to the capacitor 93, and the applied voltage V ₁ is also applied between both end electrodes of the flash lamp FL. The Rukoto. When the IGBT 96 is turned on in a state where charges corresponding to the applied voltage V ₁ are accumulated in the capacitor 93 and a high voltage is applied to the trigger electrode 91 in synchronization therewith, the charges accumulated in the capacitor 93 are The flash lamp FL starts to flow between both end electrodes in the glass tube 92, and the flash lamp FL starts to emit light. The light emission waveform of the flash lamp FL is as set by the waveform setting unit 305.

When the flash lamp FL emits light, the heat treatment space 65 in the chamber 6 is irradiated with flash light. The flash light irradiated onto the heat treatment space 65 from above enters the incident surface at the tip of the first quartz rod 21 and is guided to the calorimeter 24 by the light derivation structure 20. The calorimeter 24 outputs an electrical signal obtained by converting the energy of heat generated in the black body that has absorbed the incident flash light to the energy measuring unit 301 of the control unit 3. The energy measuring unit 301 calculates the flash energy E ₁ of the flash light irradiated into the chamber 6 based on the electric signal output from the calorimeter 24. In this way, the power supply from the capacitor 93 that is charged by applying voltages V ₁ when the flash lamp FL emits light (i.e., when the flash lamp FL emits light at an applied voltages V _1), a flash lamp The flash energy E _{1 of the} flash light emitted from the FL is measured.

When the measurement at the applied voltage V ₁ is completed, the flash energy E ₂ at the applied voltage V ₂ is similarly measured. That is, the power supply unit 95 charges the capacitor 93 by applying the voltage V ₂ . Then, the flash lamp FL is caused to emit light by supplying power from the capacitor 93 charged with the applied voltage V ₂ , and the flash energy E ₂ of the flash light irradiated into the chamber 6 is converted into an electric signal output from the calorimeter 24. Based on this, the energy measurement unit 301 calculates.

Later, repeating such procedure, when the flash lamp FL emits light by the power supply from the capacitor 93 that is charged by a plurality of applied voltages _{V 1, V 2, V 3} ··· V n ( i.e., a plurality (When the flash lamp FL emits light at the applied voltages V ₁ , V ₂ , V ₃ ... V _n ), the flash energy E _{1 of the} flash light emitted from the flash lamp FL for each of the applied voltages. , E ₂ , E ₃ ... E _n are measured. This measurement operation is performed in a state where the semiconductor wafer W does not exist in the chamber 6, and may be performed, for example, for the purpose of calibrating a relational expression indicating a correlation described later between processing lots. Note that the emission waveform of the flash lamp FL set by the waveform setting unit 305 is common for all of the plurality of applied voltages. When the waveform setting unit 305 sets a different emission waveform, the energy measurement unit 301 calculates the flash energy when the flash lamp FL emits light at a plurality of applied voltages for each set emission waveform of the flash lamp FL. Measure.

  Next, based on the measurement result thus obtained, a relational expression indicating a correlation between the voltage V applied to the flash lamp FL and the flash energy E of the flash light emitted from the flash lamp FL is obtained ( Step S2). In the present embodiment, based on the measurement result obtained by the energy measurement unit 301, the correlation acquisition unit 302 of the control unit 3 linearly approximates the relationship between the applied voltage V and the flash energy E (approximate with a linear function). To do.

  FIG. 15 is a diagram illustrating an example of linear approximation of the relationship between the applied voltage V and the flash energy E. In FIG. As shown in the figure, a substantially linear relationship is recognized between the voltage V applied to the flash lamp FL and the flash energy E of the flash light emitted from the flash lamp FL. For this reason, it is reasonable to perform linear approximation on both these parameters. The correlation acquisition unit 302 linearly approximates the relationship between the applied voltage V and the flash energy E as shown in FIG. 15 using a known method (for example, the least square method), and is expressed by the following equation (1). Get the relational expression. The acquired relational expression is stored in the storage unit (ROM 32, RAM 33 or magnetic disk 34) of the control unit 3.

  In Expression (1), a and b are constants obtained by linear approximation. The constants a and b are defined by various factors such as the characteristics of the flash lamp FL, the shape in the chamber 6 and the reflectance. Further, when the light emission waveform of the flash lamp FL is different, the correlation between the applied voltage V and the flash energy E is also different. Therefore, when the waveform setting unit 305 sets a different light emission waveform, a relational expression indicating the correlation between the applied voltage V and the flash energy E of the flash light is obtained for each light emission waveform of the flash lamp FL that has been set. To do.

  Next, the reflected light intensity of the semiconductor wafer W to be processed is measured (step S3). This measurement is performed when the semiconductor wafer W to be processed is loaded into the alignment unit 130 and placed on the rotary table 133. Specifically, when the semiconductor wafer W to be processed is placed on the turntable 133, the surface of the semiconductor wafer W is irradiated with light from the measurement optical system 231. The reflected light reflected from the surface of the semiconductor wafer W is received by the measurement optical system 231 and then subjected to spectral decomposition processing by the spectroscope 235. As a result of this processing, the spectral characteristic of the reflected light intensity of the semiconductor wafer W is obtained. Input to the control unit 3. The spectral characteristic of the reflected light intensity of the semiconductor wafer W to be processed is stored in the storage unit of the control unit 3.

  On the other hand, the spectral characteristic of the reflected light intensity of the standard wafer when light is irradiated from the measurement optical system 231 is also stored in the storage unit of the control unit 3. In this embodiment, a plain bare wafer that is not patterned is used as the standard wafer. With respect to the reflected light intensity of the standard wafer, the result of actually measuring the reflected light intensity of the standard wafer by the alignment unit 130 at any timing may be stored in the storage unit of the control unit 3. If the standard wafer is a bare wafer, the spectral characteristic of the reflected light intensity is known, and the data may be stored in the storage unit of the control unit 3 in advance.

  FIG. 16 is a diagram illustrating the spectral characteristics of the reflected light intensity of the semiconductor wafer W and the standard wafer to be processed. In the figure, the vertical axis indicates the reflected light intensity, and the horizontal axis indicates the wave number (the reciprocal of the wavelength). Also, the dotted line indicates the reflected light intensity of the standard wafer, and the dashed line indicates the reflected light intensity of the semiconductor wafer W to be processed. In FIG. 16, the solid line indicates the reflected light intensity of the ideal mirror that totally reflects. The total reflected light intensity is obtained when an ideal mirror having a reflectance of 100% is carried into the alignment unit 130 and the reflected light intensity is measured, but such an ideal mirror does not actually exist. Therefore, a theoretical value (calculated value) is used, which coincides with the spectral characteristic of the light emission intensity of the light source (halogen lamp) built in the projector 233.

An emissivity ratio ε _r , which is a ratio of the emissivity of the standard wafer to the emissivity of the semiconductor wafer W to be processed, is calculated from the reflected light intensity of the semiconductor wafer W to be processed and the reflected light intensity of the standard wafer ( Step S4). The emissivity ratio ε _r is calculated by the emissivity ratio calculating unit 303 of the control unit 3 according to the following equation (2).

In equation (2), ε _b is the emissivity of the standard wafer (bare wafer), and ε _samp is the emissivity of the semiconductor wafer W to be processed. Further, I _cal is the reflected light intensity of the total reflection, I _std is the reflected light intensity of the standard wafer, and I _samp is the reflected light intensity of the semiconductor wafer W to be processed. K is the wave number shown on the horizontal axis of FIG.

In FIG. 16, the value obtained by integrating the reflected light intensity (I) with the wave number (k) is the light energy of the reflected light. Therefore, the area of the region sandwiched between the solid line and the dotted line in FIG. 16 is the light energy absorbed by the standard wafer in the wave number range of 1/800 to 1/400 (nm ⁻¹ ), and is sandwiched between the solid line and the alternate long and short dash line. The area of the region is the light energy absorbed by the semiconductor wafer W to be processed in the same wave number range. Therefore, in equation (2), the ratio of the light energy absorbed by the standard wafer to the light energy absorbed by the semiconductor wafer W to be processed is the radiation of the standard wafer with respect to the emissivity ε _samp of the semiconductor wafer W to be processed. It is calculated as an emissivity ratio ε _r that is a ratio of the rate ε _b . In general, the emissivity ε _samp of the processing target semiconductor wafer W having a pattern formed on the surface is larger than the emissivity ε _{b of a} standard wafer on which no pattern is formed, and the emissivity ratio ε _r is smaller than 1. Become.

The emissivity ratio ε _r between the standard wafer calculated by the emissivity ratio calculation unit 303 and the semiconductor wafer W to be processed is stored in the storage unit of the control unit 3. In the calculation of equation (2), the wave number range for integrating the reflected light intensity is 1/800 to 1/400 (nm ⁻¹ ), that is, the visible light range is the emission wavelength of the xenon flash lamp FL. Considering the fact that the wavelength range from the ultraviolet range to the infrared range and that the silicon semiconductor wafer W transmits infrared rays, the wavelength that is within the emission wavelength range of the xenon flash lamp FL and contributes to the heating of the semiconductor wafer W The area is selected.

Next, the relational expression indicating the correlation between the voltage V applied to the flash lamp FL acquired by the correlation acquisition unit 302 in step S2 and the flash energy E of flash light and the emissivity ratio calculation unit 303 calculate in step S4. Based on the emissivity ratio ε _r of the standard wafer with respect to the processed semiconductor wafer W, the applied voltage calculation unit 304 of the control unit 3 calculates the applied voltage for the semiconductor wafer W to be processed (step S5). .

In order for the semiconductor wafer W to be processed to absorb the same amount of energy as the standard wafer absorbs when the flash light is irradiated from the flash lamp FL to the standard wafer with the flash energy E _b , It is necessary to irradiate the semiconductor wafer W to be processed from the flash lamp FL with the flash energy E _samp obtained in (3).

Since the target semiconductor wafer W on which the pattern is formed has a higher absorption rate (that is, higher emissivity) than the standard wafer on which the pattern is not formed, the same amount of flash energy as the standard wafer is processed. In order to make W absorb, it is necessary to make the flash energy of the flash light irradiated smaller than that of the standard wafer. Specifically, as shown in Expression (3), it is necessary to perform flash irradiation with a flash energy E _samp obtained by multiplying the flash energy E _b of the flash light irradiated to the standard wafer by the emissivity ratio ε _r. .

From this equation (3) and equation (1), the following equation (4) is derived. Here, V _samp is an applied voltage to the flash lamp FL when the semiconductor wafer W to be processed is irradiated with flash light. V _b is an applied voltage to the flash lamp FL when the standard wafer is irradiated with flash light of flash energy E _b .

The applied voltage calculation unit 304 absorbs an energy equivalent to that absorbed by the standard wafer when the standard wafer is irradiated with flash light with the flash energy _Eb from the equation (4) into the semiconductor wafer W to be processed. The applied voltage V _samp for the flash lamp FL required for the calculation is calculated.

For a standard wafer, the appropriate flash energy value of the flash light to be emitted from the flash lamp FL has been found. An appropriate flash energy value is an energy value at which activation of implanted impurities is favorably performed without causing wafer cracking. If an appropriate flash energy value of the flash light to be irradiated on such a standard wafer is set as E _b , an energy equivalent to that absorbed by the standard wafer when the appropriate flash light irradiation is performed is treated. The applied voltage V _samp to the flash lamp FL necessary for absorption by the semiconductor wafer W can be calculated from the equation (4). That is, the applied voltage V _samp that can perform an appropriate flash heat treatment on the semiconductor wafer W to be processed can be calculated from the equation (4). V _b may be obtained by applying an appropriate flash energy E _b for the standard wafer to the equation (1), or may be obtained experimentally in advance.

As described above, after the applied voltage calculation unit 304 calculates the applied voltage V _samp that can perform an appropriate flash heating process on the semiconductor wafer W to be processed, the flash heating unit 160 calculates the applied voltage thus calculated. The semiconductor wafer W is actually irradiated with flash light from the flash lamp FL at V _samp (step S6).

<2-4. Processing in flash heating section>
Next, the processing operation of the semiconductor wafer W in the flash heating unit 160 will be described. 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 the position of the holding unit 7 when the semiconductor wafer W is irradiated with flash 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 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 transfer robot 150 causes the transfer arm 151 a holding the semiconductor wafer W to be processed to enter the chamber 6 from the transfer opening 66. The transfer robot 150 advances the transfer arm 151a to above the three support pins 70, and then slightly lowers the transfer arm 151a. At this time, the semiconductor wafer W held on the transfer arm 151 a is transferred to the three support pins 70.

  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 and placed on the three support pins 70, the transfer robot 150 moves the transfer arm 151 a out of the chamber 6. Then, after 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.

  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 700 ° C., preferably about 350 ° C. to 600 ° C. (500 ° C. in the present embodiment) at which impurities added to the semiconductor wafer W do not 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. When performing flash light irradiation from the flash lamp FL, the power supply unit 95 precharges the capacitor 93 with the applied voltage V _samp calculated by the applied voltage calculating unit 304 as described above. The light emission waveform of the flash lamp FL set by the waveform setting unit 305 was used to obtain the relational expression (1) indicating the correlation between the applied voltage V and the flash energy E when calculating the applied voltage V _samp . Keep the same as the emission waveform.

When the capacitor 93 is charged with the applied voltage V _{samp and the} IGBT control unit 98 outputs a pulse signal to the gate of the IGBT 96 and a high voltage is applied to the trigger electrode 91 in synchronization therewith, the capacitor 93 The electric charge accumulated in the flash lamp FL starts to flow as a current between both end electrodes in the glass tube 92 of the flash lamp FL, and the flash light irradiation from the flash lamp FL is executed. 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.

The applied voltage V _samp is calculated as an applied voltage necessary for the semiconductor wafer W to be processed to absorb the same amount of flash energy as that absorbed by a standard wafer that has been subjected to appropriate flash heat treatment. . That is, the applied voltage V _samp is calculated so that an appropriate flash heat treatment can be performed on the semiconductor wafer W to be processed. Accordingly, if power is supplied to the flash lamp FL from the capacitor 93 charged with the applied voltage V _samp and the flash lamp FL is _caused to emit light with the same light emission waveform as that used when calculating the applied voltage V _samp. The semiconductor wafer W to be processed can be irradiated with flash light of appropriate flash energy from the flash lamp FL. 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 1000 ° C. or more, and the impurities added to the semiconductor wafer W are activated. Later, the surface temperature drops rapidly.

  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 transfer robot 150 causes the transfer arm 151 b to enter the chamber 6 through the transfer opening 66. The transfer robot 150 advances the transfer arm 151b to below the semiconductor wafer W supported by the three support pins 70, and then raises the transfer arm 151b. As a result, the semiconductor wafer W placed on the support pins 70 is transferred to the transfer arm 151b. Thereafter, the transfer robot 150 causes the transfer arm 151 b that supports the semiconductor wafer W after the flash heat treatment to leave the chamber 6.

  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.

<3. Advantages of heat treatment apparatus of the present embodiment>
In the present embodiment, first, the flash lamp FL is caused to emit light at a plurality of applied voltages, and the flash energy of the flash light emitted from the flash lamp FL is measured for each of the applied voltages. Next, a relational expression indicating the correlation between the voltage applied to the flash lamp FL and the flash energy of the flash light emitted from the flash lamp FL is acquired based on the measurement result. Further, the reflected light intensity of the semiconductor wafer W to be processed is measured, and the emissivity ratio between the emissivity of the standard wafer and the emissivity of the semiconductor wafer W to be processed is calculated from the value and the reflected light intensity of the standard wafer. . Then, based on the relational expression indicating the correlation between the applied voltage and the flash energy and the emissivity ratio between the standard wafer and the processing target semiconductor wafer W, the processing target semiconductor wafer absorbs the same amount of flash energy as the standard wafer absorbs. The applied voltage required for W to absorb is calculated. The flash lamp FL is supplied with power from the capacitor 93, and the voltage applied to the flash lamp FL is the same as the voltage (charge voltage) applied to the capacitor 93 that supplies power to the flash lamp FL.

  In this way, it is not necessary to open the chamber 6 and install a calorimeter as in the conventional case, and the flash energy equivalent to that absorbed by the standard wafer is applied to the semiconductor wafer W to be processed. The voltage applied to the flash lamp FL necessary for absorption can be easily set. Therefore, there is no concern that the inside of the chamber 6 is contaminated when setting the voltage applied to the flash lamp FL. Then, it calculates the applied voltage necessary for the semiconductor wafer W to be processed to absorb the same amount of flash energy as that absorbed by a standard wafer that has been subjected to appropriate flash heat treatment, and charges the capacitor 93 with the applied voltage. Then, it is possible to execute an appropriate flash heating process on the semiconductor wafer W to be processed.

  In particular, in this embodiment, the waveform setting unit 305 of the control unit 3 can freely set the light emission waveform of the flash lamp FL based on the input content from the input unit 36, but this is the case when a new light emission waveform is set. However, the voltage applied to the flash lamp FL can be easily set for each light emission waveform by the above method. That is, since it is not necessary to open the chamber 6 and install a calorimeter every time a new light emission waveform is set, the burden of setting the applied voltage to the flash lamp FL when the light emission waveform is changed is extremely light. It becomes.

In addition, every time a semiconductor wafer W to be processed is carried into the alignment unit 130, the reflected light intensity of the semiconductor wafer W is measured, and the emissivity ratio ε _r between the standard wafer and the semiconductor wafer W is calculated. Anyway. In this case, the applied voltage calculation unit 304 sets the applied voltage for each semiconductor wafer W to be processed. In this way, even if the emissivity of the semiconductor wafer W to be processed is different, an appropriate applied voltage can be set according to the emissivity.

Further, in the present embodiment, the emissivity ratio ε _r between the standard wafer and the semiconductor wafer W to be processed is calculated by Equation (2) at 400 nm to 800 nm that is within the emission wavelength range of the flash lamp FL. ing. For this reason, the emissivity ratio ε _r becomes suitable for the light emission of the flash lamp FL, and the calculation accuracy of the voltage applied to the flash lamp FL can be improved.

<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 the above-described embodiment, the correlation acquisition unit 302 linearly approximates the relationship between the applied voltage V and the flash energy E. However, the present invention is not limited to this, and a higher-order function that is a quadratic function or higher is used. The relational expression indicating the correlation may be acquired by approximation.

Further, since the reflected light intensity in the equation (2) for calculating the emissivity ratio ε _r is that of a halogen lamp as the light source, weighting correction is further performed in consideration of the spectral distribution characteristics of the flash lamp FL in the equation (2). You may do it. Specifically, the reflected light intensity at a stronger wavelength is multiplied by a larger coefficient in the spectral distribution of the flash lamp FL.

  Further, in the above embodiment, a plain bare wafer that is not patterned is used as a standard wafer, but instead of this, another type of wafer having a known spectral characteristic of reflected light intensity is used. Also good. For example, a blanket wafer obtained by implanting impurities into a bare wafer by an ion implantation method may be used as a standard wafer.

  The setting of the waveform of the pulse signal output to the gate of the IGBT 96 is not limited to inputting parameters such as the pulse width from the input unit 36 one by one. For example, the operator directly displays the waveform from the input unit 36 graphically. May be inputted, or a waveform previously set and stored in a storage unit such as a magnetic disk may be read out, or may be downloaded from the outside of the heat treatment apparatus 100. .

  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.

  Further, instead of the IGBT 96, another transistor that can turn on and off the circuit according to the signal level input to the gate may be used. 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.

  In the above embodiment, the semiconductor wafer W is preheated by placing it on the hot plate 71. However, the preheating method is not limited to this, and a halogen lamp is provided to provide light. The semiconductor wafer W may be preheated to the preheating temperature T1 by irradiation.

  Also, the upper transfer arm 151a of the transfer robot 150 is designed as a dedicated arm for holding the unprocessed semiconductor wafer W, and the lower transfer arm 151b is designed as a dedicated arm for holding the processed semiconductor wafer W. Thus, the transport robot 150 can be reduced in size and transport reliability can be improved.

  The optical measurement unit 230 is not limited to being installed in the alignment unit 130, and may be installed at any position on the path for transporting the semiconductor wafer W from the indexer unit 101 to the flash heating unit 160.

  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.

2 Light Measurement Unit 3 Control Unit 4 Holding Unit Lifting Mechanism 5 Lamp House 6 Chamber 7 Holding Unit 24 Calorimeter 31 CPU
36 Input Unit 93 Capacitor 95 Power Supply Unit 96 IGBT
98 IGBT Control Unit 100 Heat Treatment Device 101 Indexer Unit 130 Alignment Unit 132 Wafer Holding Unit 133 Rotating Table 140 Cooling Unit 150 Transfer Robot 160 Flash Heating Unit 170 Transfer Chamber 230 Optical Measurement Unit 231 Measurement Optical System 233 Projector 235 Spectroscope 301 Energy Measurement Unit 302 Correlation Acquisition Unit 303 Emissivity Ratio Calculation Unit 304 Applied Voltage Calculation Unit 305 Waveform Setting Unit FL Flash Lamp W Semiconductor Wafer

Claims (7)

An applied voltage setting method for setting an applied voltage to a flash lamp that irradiates and heats a substrate with flash light,
An energy measuring step of causing the flash lamp to emit light at a plurality of applied voltages and measuring flash energy of flash light emitted from the flash lamp for each of the plurality of applied voltages;
A correlation acquisition step of acquiring a relational expression indicating a correlation between the voltage applied to the flash lamp and the flash energy of the flash light irradiated from the flash lamp based on the measurement result obtained in the energy measurement step;
An emissivity ratio calculating step of measuring the reflected light intensity of the substrate to be processed and calculating an emissivity ratio between the emissivity of the standard substrate and the emissivity of the substrate to be processed;
Based on the relational expression showing the correlation between the applied voltage and flash energy acquired in the correlation acquisition step and the emissivity ratio between the standard substrate and the substrate to be processed calculated in the emissivity ratio calculation step, An applied voltage calculating step for calculating an applied voltage required for the substrate to be processed to absorb the same amount of flash energy as the standard substrate absorbs;
Equipped with a,
The energy measuring step measures the flash energy by causing the flash lamp to emit light at a plurality of applied voltages for each emission waveform of the flash lamp,
The correlation acquisition step acquires a relational expression indicating a correlation between an applied voltage and flash energy for each light emission waveform of a flash lamp .   A heat treatment method for heating a substrate by irradiating the substrate with flash light,
  A waveform setting process for setting the emission waveform of the flash lamp;
  An energy measuring step of causing the flash lamp to emit light at a plurality of applied voltages and measuring flash energy of flash light emitted from the flash lamp for each of the plurality of applied voltages;
  A correlation acquisition step of acquiring a relational expression indicating a correlation between the voltage applied to the flash lamp and the flash energy of the flash light irradiated from the flash lamp based on the measurement result obtained in the energy measurement step;
  An emissivity ratio calculating step of measuring the reflected light intensity of the substrate to be processed and calculating an emissivity ratio between the emissivity of the standard substrate and the emissivity of the substrate to be processed;
  Based on the relational expression showing the correlation between the applied voltage and flash energy acquired in the correlation acquisition step and the emissivity ratio between the standard substrate and the substrate to be processed calculated in the emissivity ratio calculation step, An applied voltage calculating step for calculating an applied voltage required for the substrate to be processed to absorb the same amount of flash energy as the standard substrate absorbs;
  A flash light irradiation step of charging a capacitor with the applied voltage calculated in the applied voltage calculation step, supplying power to the flash lamp from the capacitor and irradiating the processing target substrate with flash light,
With
  The energy measuring step measures the flash energy by causing the flash lamp to emit light at a plurality of applied voltages for each emission waveform of the flash lamp set in the waveform setting step,
  The correlation obtaining step obtains a relational expression indicating a correlation between an applied voltage and flash energy for each light emission waveform of a flash lamp.   The heat treatment method according to claim 2,
  A heat treatment method, wherein the emissivity ratio calculation step and the applied voltage calculation step are executed for each substrate to be processed.   In the heat processing method of Claim 2 or Claim 3,
  The emissivity ratio calculating step calculates an emissivity ratio between a standard substrate and a substrate to be processed within a light emission wavelength range of a flash lamp.   A heat treatment apparatus for heating a substrate by irradiating the substrate with flash light,
  Holding means for holding the substrate;
  A flash lamp for irradiating flash light onto the substrate held by the holding means;
  A capacitor for supplying power to the flash lamp;
  Energy measuring means for measuring flash energy of flash light emitted from the flash lamp for each of the plurality of applied voltages when the flash lamp emits light by power supply from a capacitor charged with a plurality of applied voltages;
  Correlation acquiring means for acquiring a relational expression indicating a correlation between an applied voltage to the flash lamp and flash energy of flash light emitted from the flash lamp based on a measurement result obtained by the energy measuring means;
  Reflected light intensity measuring means for measuring the reflected light intensity of the substrate to be processed;
  An emissivity ratio calculating means for calculating an emissivity ratio between the emissivity of the standard substrate and the emissivity of the substrate to be processed based on the measurement result obtained by the reflected light intensity measuring means;
  Based on the relational expression indicating the correlation between the applied voltage acquired by the correlation acquisition means and the flash energy and the emissivity ratio between the standard substrate calculated by the emissivity ratio calculation means and the substrate to be processed, An applied voltage calculating means for calculating an applied voltage required to cause the substrate to be processed to absorb the same amount of flash energy as that absorbed by
  Control means for charging the capacitor with the applied voltage calculated by the applied voltage calculating means, and supplying the flash lamp with power from the capacitor to irradiate the processing target substrate held in the holding means with flash light;
  Waveform setting means for setting the emission waveform of the flash lamp;
With
  The energy measuring means measures the flash energy when the flash lamp emits light by a capacitor charged with a plurality of applied voltages for each light emission waveform of the flash lamp set by the waveform setting means,
  The said correlation acquisition means acquires the relational expression which shows the correlation of an applied voltage and flash energy for every light emission waveform of a flash lamp, The heat processing apparatus characterized by the above-mentioned.   The heat treatment apparatus according to claim 5,
  The reflected light intensity measuring means measures the reflected light intensity for each substrate to be processed.   In the heat treatment apparatus according to claim 5 or 6,
  The emissivity ratio calculating means calculates the emissivity ratio between the standard substrate and the substrate to be processed within the range of the emission wavelength range of the flash lamp.

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