JP3660254B2 - Substrate heat treatment equipment - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
In the present invention, a semiconductor wafer, a glass substrate for a liquid crystal display device, a glass substrate for a photomask, a substrate for an optical disk, etc. (hereinafter referred to as “substrate”) are carried one by one into a heat treatment furnace, and the substrates are irradiated by light irradiation. The present invention relates to a substrate heat treatment apparatus for performing heat treatment by heating.
[0002]
[Prior art]
In a semiconductor device manufacturing process, like a lamp annealing apparatus or a CVD apparatus, a substrate, for example, a semiconductor wafer is carried into a heat treatment furnace one by one, and the wafer is heated and heat-treated by irradiating the substrate with light. Leaf-type heat treatment apparatuses are widely used in various processes.
[0003]
By the way, in order to achieve high integration of semiconductor devices, high-speed operation as well as miniaturization of devices is an important factor. For example, in order to increase the operation speed of the diode, it is necessary to reduce the depth of the PN junction. Therefore, it is necessary to electrically activate ions such as B, As, and P implanted into the wafer without diffusing them. There is. For this purpose, a device is required that rapidly raises the wafer to an ion activation temperature (for example, 150 ° C./second) and rapidly cools the wafer to a temperature at which ions do not diffuse after the temperature rise.
[0004]
The lamp annealing apparatus has been developed from the above-mentioned necessity. Conventionally, a method of naturally cooling the lamp as a heating source by turning off the lamp as a heating source has been adopted for cooling the wafer in the lamp annealing apparatus. It was. Also, compressed air or nitrogen is blown out from the nozzle of the gas injection device toward the outer wall surface of the heat treatment furnace that holds the heat-treated wafer inside, and the furnace wall of the heat treatment furnace is cooled to indirectly attach the wafer in the furnace. The method of cooling was also performed.
[0005]
[Problems to be solved by the invention]
However, with the method of naturally cooling the wafer, it is difficult to rapidly cool the wafer. In addition, the method of indirectly cooling the wafer in the furnace by cooling the furnace wall of the heat treatment furnace improves the throughput by quickly cooling the wafer to the temperature at which the wafer is taken out from the furnace (eg, 300 ° C. to 500 ° C.). In this method, it is difficult to rapidly cool the wafer to such an extent that ion diffusion is suppressed. That is, in order to form a shallow PN junction on a wafer, a low voltage ion implanter is used to implant a required amount of ions shallowly into the wafer, and the wafer is subjected to an ion activation temperature (for example, in a subsequent heat treatment) It is necessary to cool the wafer in a short time to a temperature (about 700 ° C.) at which ion diffusion is suppressed as much as possible after the temperature is raised to 1000 ° C. at a high speed. However, the conventional method of indirectly cooling the wafer can mainly increase the cooling rate on the low temperature side and shorten the time for cooling the wafer to the extraction temperature, but on the high temperature side, ion diffusion is as much as possible. The time for cooling the wafer to a temperature that can be suppressed cannot be shortened.
[0006]
The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a substrate heat treatment apparatus capable of rapidly cooling a substrate on a high temperature side.
[0007]
[Means for Solving the Problems]
The invention according to claim 1 is directed to a heat treatment furnace in which at least the upper furnace wall is formed of a light-transmitting material and the substrate is carried and held therein, and at least the upper surface of the substrate held in the heat treatment furnace is opposed to the heat treatment furnace. And a heating means that heats the substrate by irradiating the substrate with light through a furnace wall formed of the light-transmitting material, and a substrate held in the heat treatment furnace. A movable cooling plate supported so as to be able to reciprocate between a cooling position in contact with or close to and a standby position in contact with or close to the lower furnace wall of the heat treatment furnace, and drive means for reciprocating the movable cooling plate; Gas introduction means for introducing gas between the movable cooling plate and the lower furnace wall of the heat treatment furnace at the standby position, and the gas introduction when the movable cooling plate is moved from the standby position to the cooling position by the driving means. And control means for controlling to actuate the stage, and further comprising a.
[0008]
The invention according to claim 2 is the heat treatment apparatus according to claim 1, wherein the movable cooling plate is formed of quartz glass.
[0009]
The invention according to claim 3 is the heat treatment apparatus according to claim 1 or 2, wherein the movable cooling plate is cooled to a temperature of 50 ° C. or less.
[0010]
The invention according to claim 4 is the heat treatment apparatus according to any one of claims 1 to 3, wherein the lower furnace wall of the heat treatment furnace is water-cooled, and the movable cooling plate is in contact with the water-cooled lower furnace wall. Alternatively, the movable cooling plate is cooled in the vicinity.
[0011]
In the heat treatment apparatus according to the first aspect of the present invention, the heating means irradiates and heats the substrate held in the heat treatment furnace to heat the substrate. Until that time, the movable cooling plate is cooled by being stopped at a standby position that is in contact with or close to the lower furnace wall of the heat treatment furnace. As soon as the heat treatment is completed, heating of the substrate by the heating means is stopped, and the driving means and the gas introducing means are respectively operated by the control means, and the movable cooling plate and the heat treatment furnace at the standby position are operated by the gas introducing means. Gas is introduced between the lower furnace wall and the movable cooling plate is moved from the standby position toward the cooling position by the driving means. As described above, when the movable cooling plate is moved from the standby position to the cooling position, gas is introduced between the movable cooling plate and the lower furnace wall of the heat treatment furnace, so that the movable cooling plate is moved along with the movement of the movable cooling plate. The vacuum state formed between the plate and the lower furnace wall of the heat treatment furnace does not cause the movable cooling plate to remain in close contact with the lower furnace wall of the heat treatment furnace or the movement of the movable cooling plate is suppressed. Then, the movable cooling plate quickly moves from the standby position to the cooling position and comes into contact with or close to the substrate, rapidly taking away the amount of heat of the substrate and rapidly cooling the substrate on the high temperature side.
[0012]
In the heat treatment apparatus according to the second aspect of the present invention, since the movable cooling plate is formed of quartz glass, even if the movable cooling plate is interposed between the substrate and the lower furnace wall of the heat treatment furnace, There is no problem in measuring the temperature of the substrate and the substrate support member by a radiation thermometer or the like performed on the furnace wall surface.
[0013]
In the heat treatment apparatus of the invention according to claim 3, by cooling the movable cooling plate to a temperature of 50 ° C. or lower, the effect of cooling the substrate by the movable cooling plate can be reliably obtained.
[0014]
In the heat treatment apparatus of the invention according to claim 4, the movable cooling plate is reliably cooled at the standby position by contacting or approaching the water-cooled lower furnace wall.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.
[0016]
FIG. 1 shows an example of an embodiment of the present invention, and shows a schematic configuration of a lamp annealing apparatus, which is one of heat treatment apparatuses for a substrate such as a semiconductor wafer, in a cut end face.
[0017]
The lamp annealing apparatus includes a heat treatment furnace 10 having an opening 12 for carrying in and carrying out a semiconductor wafer W. The opening 12 of the heat treatment furnace 10 is closed by a shutter 14 so as to be freely opened and closed. At least the upper furnace wall of the heat treatment furnace 10 is a light incident window 16. A light incident window 16, which is a partition wall between the reaction chamber 18 of the heat treatment furnace 10 and a lamp house 20 (not shown in detail) which is a heating source, is formed of a material having infrared transparency, such as quartz glass. The radiation light emitted from the lamp of the house 20 is transmitted efficiently. This light incident window 16 is incorporated in a quartz glass window holder 22 so that it can be removed, and is sealed by an O-ring 24 and disposed at the upper part of the reaction chamber 18.
[0018]
Although not shown, a support arm for supporting the wafer W in a horizontal posture is provided on the surface facing the opening 12 of the heat treatment furnace 10, and the wafer W before heat treatment is carried into the heat treatment furnace 10 from the alignment unit. A wafer carry-in / out device for carrying out the wafer W after the heat treatment from the heat treatment furnace 10 is provided.
[0019]
A wafer support ring 26 formed of silicon carbide (SiC) or the like is disposed inside the heat treatment furnace 10, and the wafer support ring 26 is placed horizontally on the upper end portion of the wafer support cylindrical holder 28 formed of quartz glass. It is fixed with. The wafer support cylindrical holder 28 is held on the wafer rotation mechanism 32 via an adjuster 30 for adjusting the horizontal state of the wafer W. The wafer W is supported on the wafer support ring 26 and is rotated by the wafer rotation mechanism 32. In addition, a wafer push-up mechanism 36 is provided that has a plurality of, for example, three support pins 34 that contact the lower surface of the wafer W to support the wafer W and reciprocate the support pins 34 in the vertical direction.
[0020]
The wafer W before the heat treatment is supported by the support arm of the wafer carry-in / out apparatus, is carried into the heat treatment furnace 10, is transferred onto the raised support pins 34 of the wafer push-up mechanism 36, and then the support pins 34 are lowered. As a result, it is placed on the wafer support ring 26 and supported in a horizontal position. Further, after the heat treatment, the wafer W is lifted from the wafer support ring 26 by raising the support pins 34 of the wafer push-up mechanism 36 and then transferred from the support pins 34 onto the support arms of the wafer loading / unloading apparatus. It is replaced and carried out of the heat treatment furnace 10 by the wafer carry-in / out device.
[0021]
In addition, a plurality of gas blowing holes are formed in the heat treatment furnace 10 so as to be opposed to the upper surface of the wafer W supported on the wafer support ring 26 and made of a material having infrared transparency, such as quartz glass. A shower plate 38 is provided. Between the shower plate 38 and the light incident window 16 is a gas introduction chamber 40 into which a reaction gas is introduced. The gas introduction chamber 40 is connected to a reaction gas supply source through a gas introduction path 42. Yes. Then, the reaction gas supplied from the reaction gas supply source and introduced into the gas introduction chamber 40 is uniformly blown out to the entire upper surface of the wafer W on the wafer support ring 26 through the plurality of gas blowing holes of the shower plate 38. It is like that.
[0022]
The lower furnace wall of the heat treatment furnace 10 is constituted by a reflector plate 44. The reflection plate 44 is made of stainless steel, and the surface facing the wafer W is polished to a mirror surface in order to obtain high reflectivity. A cooling water passage 46 is formed inside the reflection plate 44, and the reflection plate 44 is cooled by flowing cooling water through the passage 46. Two types of radiation thermometers, that is, a support ring temperature detection radiation thermometer 48 and a wafer temperature detection radiation thermometer 50 are attached to the reflection plate 44. The support ring temperature detecting radiation thermometer 48 is installed so that the focus is on a position on the outer side of the wafer W on the wafer support ring 26 about 5 mm outward. The wafer temperature detecting radiation thermometer 50 is attached to a plurality of positions, for example, a position corresponding to the approximate center of the wafer W, a position corresponding to the radius of the wafer W, and a position corresponding to the outer periphery of the wafer W.
[0023]
A movable cooling plate 52 is disposed on the side of the reflecting plate 44 facing the wafer W. The movable cooling plate 52 is made of, for example, quartz glass. The movable cooling plate 52 is held by a cooling plate vertical mechanism 54 and is moved at a high speed in the vertical direction by a driving device such as an air cylinder of the cooling plate vertical mechanism 54 to contact the wafer W on the wafer support ring 26. Alternatively, it reciprocates between a close upper cooling position and a standby position in contact with or close to the reflector 44. In addition, a gas introduction path 56 for supplying a gas, for example, nitrogen gas, between the reflection plate 44 and the movable cooling plate 52 is provided at the central position of the reflection plate 44. The gas introduction path 56 is illustrated in the drawing. Not connected to the nitrogen gas supply device. A controller (not shown) for controlling the cooling plate up-and-down mechanism 54 and the nitrogen gas supply device is provided, and at the same time or slightly before the heat treatment of the wafer W is completed and the lamp of the lamp house 20 is turned off. Further, the cooling plate vertical mechanism 54 and the nitrogen gas supply device are operated by a control signal from the controller, and the movable cooling plate 52 is moved from the standby position to the cooling position at high speed.
[0024]
In addition to the reflector 44, the movable cooling plate 52 and the cooling plate vertical mechanism 54, the wafer rotation mechanism 32, adjuster 30, wafer support cylindrical holder 28, wafer support ring 26 and the like are integrally connected to a metal bellows 58. It is driven by an up / down mechanism 60 such as a reflector so that the volume of the reaction chamber 18 can be changed. This change in volume has three stages depending on the position of the wafer W: a wafer upper stage position A, a wafer middle stage position B, and a wafer lower stage position C. Wafer upper stage position A is a position during heat treatment of wafer W, wafer middle stage position B is a position for purging gas accumulated between wafer W and movable cooling plate 52, and wafer lower stage position C is This is a position where the wafer W is taken in and out of the heat treatment furnace 10.
[0025]
An upper exhaust port 62 for exhausting the wafer W during heat treatment is formed in the upper part of the heat treatment furnace 10. During the heat treatment of the wafer W, the reaction gas is introduced into the gas introduction chamber 40 through the gas introduction path 42, and the wafer W on the wafer support ring 26 is formed from the plurality of gas blowing holes of the shower plate 38. After blowing out to the entire upper surface, the wafer W passes through the upper surface of the wafer support ring 26 from the outer periphery and is discharged out of the heat treatment furnace 10 from the upper exhaust port 62.
[0026]
Further, a purge gas introduction port 64 for introducing a reaction gas into the heat treatment 10 in order to purge the gas accumulated between the wafer W and the movable cooling plate 52 at the wafer middle stage position B below the upper stage exhaust port 62. Is formed. Further, an intermediate exhaust port 66 is formed below the purge gas introduction port 64. The middle exhaust port 66 is provided to separate the reaction chamber 18 and the periphery of the wafer rotation mechanism 32 with a gas flow. That is, the gas in the reaction chamber 18 (sometimes corrosive gas) does not flow around the wafer rotation mechanism 32, and the gas (including particulate dust) around the wafer rotation mechanism 32 is in the reaction chamber 18. The gas is exhausted while adjusting by the middle exhaust so that it does not rise.
[0027]
In addition, a gas purge port 68 and a lower exhaust port 70 are formed in order to quickly exhaust particulate dust that may be discharged from the wafer rotation mechanism 32, the metal bellows 58, and the like out of the heat treatment furnace 10. Normally, nitrogen gas is introduced from the gas purge port 68, and the space volume of the reaction chamber 18 increases or decreases as the reflector 44 moves up and down, so that the gas in the reaction chamber 18 flows around the wafer rotation mechanism 32. Conversely, the flow rate of the introduced gas is adjusted in accordance with the increase or decrease in the space volume of the reaction chamber 18 so as to prevent the gas around the wafer rotation mechanism 32 from flowing into the reaction chamber 18.
Further, in order to prevent air from being introduced into the reaction chamber 18 from the wafer loading / unloading opening 12 when the shutter 14 is opened and closed, a purge gas such as nitrogen gas introduced from the purge gas inlet 64 into the heat treatment furnace 10 is supplied to the furnace outlet. A furnace port exhaust 72 is provided to allow flow in the direction.
[0028]
A reference numeral 74 in FIG. 1 is a stopper for preventing the wafer W, which is moved in the vertical direction by the vertical mechanism 60 such as a reflector, from further rising beyond the wafer upper stage position C. Reference numeral 76 denotes a light-shielding ring for blocking the stray light from the lamp so that the lamp light from the lamp house 20 does not enter the radiation thermometers 48 and 50 when the wafer W is heat-treated at the wafer upper stage position C. The light shielding ring 76 is formed in an annular shape with SiC or the like.
[0029]
In the lamp annealing apparatus having the above-described configuration, the heat treatment of the wafer W is performed as usual by irradiating the wafer W with light from the lamp of the lamp house 20 to heat the wafer W. Before and during the heat treatment, the movable cooling plate 52 is stopped at a standby position in contact with or close to the reflecting plate 44 as shown by a solid line, as shown in a partial enlarged sectional view in FIG. The movable cooling plate 52 is cooled to substantially the same temperature as the water-cooled reflection plate 44, for example, 30 ° C. to 50 ° C.
[0030]
When the heat treatment of the wafer W is completed and the lamp of the lamp house 20 is turned off, at the same time or shortly before, the cooling plate elevating mechanism 54 and the nitrogen gas supply device are respectively operated by the controller, and the gas introduction path 56 is operated. Nitrogen gas is introduced between the movable cooling plate 52 and the reflection plate 44, and the movable cooling plate 52 is moved upward from the standby position. Then, nitrogen gas is introduced between the movable cooling plate 52 and the reflecting plate 44, so that the movable cooling plate 52 is easily detached from the reflecting plate 44 and is quickly raised by the air cylinder of the cooling plate vertical mechanism 54. As shown by the two-dot chain line, it quickly moves to the cooling position and stops. Thus, when the low-temperature movable cooling plate 52 contacts or approaches the wafer W on the wafer support ring 26, the movable cooling plate 52 rapidly takes away the heat amount of the wafer W, and the wafer W rapidly rises on the high temperature side. Allow to cool.
[0031]
FIG. 3 compares the temperature drop of each wafer W when the wafer W is cooled rapidly by bringing the movable cooling plate 52 close to the wafer W immediately after the heat treatment and when the wafer W is naturally cooled. FIG. A solid line a is when the wafer W is cooled by the movable cooling plate 52, and a broken line b is when the wafer W is naturally cooled. As shown by the solid line a, when the wafer W is cooled by the movable cooling plate 52, the cooling rate increases on the high temperature side (700 ° C. to 1000 ° C.), and the temperature is about 700 ° C., which is a temperature at which ion diffusion is suppressed as much as possible. Cools to temperature in a short time.
[0032]
On the low temperature side of about 500 ° C. or lower, the cooling is slower when the wafer W is cooled by the movable cooling plate 52 than when it is naturally cooled. This is because the temperature of the movable cooling plate 52 rises due to radiant heat from the wafer W on the high temperature side, and then the wafer W and the movable cooling plate 52 are naturally cooled together on the low temperature side. As a result, it takes a long time to cool the wafer W to the temperature of taking out from the furnace. However, the object of the apparatus of the present invention is to increase the cooling rate on the high temperature side, so there is no problem. Further, when the temperature of the wafer W is lowered to about 500 ° C. to 700 ° C., the movable cooling plate 52 may be moved downward to return to the original standby position.
[0033]
【The invention's effect】
When the substrate heat treatment apparatus of the invention according to claim 1 is used, the substrate can be rapidly cooled on the high temperature side. For example, in the diode manufacturing process, after the wafer is heated to the ion activation temperature at high speed, The wafer can be rapidly cooled to a temperature at which ions do not diffuse.
[0034]
In the heat treatment apparatus of the invention according to claim 2, even if a movable cooling plate is interposed between the substrate and the lower furnace wall of the heat treatment furnace, the substrate and the substrate support by the radiation thermometer etc. performed on the lower furnace wall surface of the heat treatment furnace There is no problem in measuring the temperature of the member.
[0035]
In the heat treatment apparatus according to the third aspect of the invention, the substrate can be surely rapidly cooled on the high temperature side.
[0036]
In the heat treatment apparatus of the invention according to claim 4, the movable cooling plate is reliably cooled to the desired temperature.
[Brief description of the drawings]
FIG. 1 shows an example of an embodiment of the present invention, and shows a schematic configuration of a lamp annealing apparatus, which is one of substrate heat treatment apparatuses, in a cut end face.
FIG. 2 is an enlarged longitudinal sectional view of a part of the apparatus shown in FIG.
FIG. 3 is a diagram comparing the temperature drop of each wafer when the wafer immediately after the heat treatment is rapidly cooled using the apparatus according to the present invention and when the wafer is naturally cooled.
[Explanation of symbols]
W Semiconductor wafer 10 Heat treatment furnace 12 Wafer carry-in / out opening 14 Shutter 16 Light incident window 18 Reaction chamber 20 Lamp house 26 Wafer support ring 28 Wafer support cylindrical holder 30 Adjuster 32 Wafer rotation mechanism 36 Wafer push-up mechanism 38 Shower plate 40 Gas introduction Chambers 42, 56 Gas introduction path 44 Reflector plate 46 forming the lower furnace wall of the heat treatment furnace Cooling water passages 48, 50 Radiation thermometer 52 Movable cooling plate 54 Cooling plate vertical mechanism 58 Metal bellows 60 Reflective plate vertical mechanism 62, 66 70 exhaust port 64 purge gas introduction port 68 gas purge port 72 furnace port exhaust port

Claims (4)

A heat treatment furnace in which at least an upper furnace wall is formed of a light-transmitting material, and a substrate is carried and held therein;
A heating means arranged to face at least the upper surface of the substrate held in the heat treatment furnace, and irradiates and heats the substrate through the furnace wall formed of the light transmissive material;
In a substrate heat treatment apparatus comprising:
A movable cooling plate supported so as to be reciprocally movable between a cooling position in contact with or close to a substrate held in the heat treatment furnace and a standby position in contact with or close to a lower furnace wall of the heat treatment furnace;
Driving means for reciprocating the movable cooling plate;
Gas introduction means for introducing gas between the movable cooling plate and the lower furnace wall of the heat treatment furnace at the standby position;
Control means for controlling the driving means and controlling the gas introducing means to operate when the movable cooling plate is moved from the standby position to the cooling position by the driving means;
A substrate heat treatment apparatus, further comprising: The substrate heat treatment apparatus according to claim 1, wherein the movable cooling plate is made of quartz glass. The substrate heat treatment apparatus according to claim 1, wherein the movable cooling plate is cooled to a temperature of 50 ° C. or less. The substrate according to any one of claims 1 to 3, wherein a lower furnace wall of the heat treatment furnace is water-cooled, and the movable cooling plate is cooled in contact with or in proximity to the water-cooled lower furnace wall. Heat treatment equipment.

Images