JP4290389B2 - Lamp annealing device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a lamp annealing apparatus, and more particularly to a lamp annealing apparatus having a mechanism for replacing an atmosphere in a furnace with an inert gas.
[0002]
[Prior art]
Usually, a lamp annealing apparatus has been used to eliminate residual stress generated in a semiconductor substrate such as a silicon wafer by an ion implantation apparatus or to diffuse doped impurities. In this lamp annealing apparatus, a wafer, which is a semiconductor substrate to be processed, is stored in a furnace, an inert gas is introduced into the furnace, and the semiconductor substrate is placed by an infrared lamp outside the furnace based on the atmosphere of the inert gas. It was heated and treated for a certain time.
[0003]
However, even if the atmosphere (air) in the furnace is replaced with an inert gas (nitrogen gas, argon gas, etc.), the atmosphere is not completely replaced, and sometimes a small amount of oxygen may remain in the furnace. This residual oxygen oxidizes the semiconductor substrate during the heat treatment and adversely affects the quality. Japanese Laid-Open Patent Publication No. 4-264734 discloses a lamp annealing apparatus that solves the problem of remaining oxygen.
[0004]
FIG. 3 is a view showing an example of a conventional lamp annealing apparatus. As shown in FIG. 3, the lamp annealing apparatus disclosed in Japanese Patent Laid-Open No. 4-264734 is configured to draw gas inside the tube 23 from the middle portion of the tube 23 as a furnace through the suction line 10. A suction pump 14 for exhausting air and an oxygen concentration measuring device 13 provided in the middle of the suction line 10 are provided. Further, the suction amount sucked from the tube 23 is determined by the opening degree of the needle valve 21.
[0005]
In the processing operation of the wafer 25 by this lamp annealing apparatus, first, the wafer 25 is opened at a predetermined position in the tube 23 by opening the door 4. Next, the door 4 is closed and, for example, nitrogen gas, which is a process gas, is introduced into the tube 23 from the gas introduction line 5 by controlling the flow rate of the mass flow controller 7 according to a command from the control unit 8. Separately from this, the air in the tube 23 is exhausted from the exhaust line 26 and begins to be replaced with the introduced nitrogen gas. On the other hand, air and nitrogen gas in the tube 23 are also sucked from the suction line 10.
[0006]
As the time elapses, the atmosphere in the tube 23 is diluted and replaced, and the atmosphere in the tube 23 is sucked in parallel with the diluted replacement, and the oxygen concentration in the tube 23 is measured by the oxygen concentration measuring device 13. To do. When the oxygen concentration falls below the specified value, the heating lamp 22 is turned on and the annealing process for the wafer 25 is started.
[0007]
In this way, while the oxygen concentration in the tube 23 is monitored, the annealing process is performed after the oxygen concentration in the tube 23 is reduced and completely replaced with nitrogen gas.
[0008]
[Problems to be solved by the invention]
In the conventional lamp annealing apparatus described above, the exhaust gas in the exhaust line (the exhaust capacity is large but the ultimate vacuum is low at about 650 Torr) is a viscous flow. The gas flows from the gas inlet of the tube 23 to the door 4 side of the tube 23. On the other hand, the suction line 10 is also a viscous flow, and the introduced gas flow is in two directions. As a result, the introduced gas stagnates near the wafer 25 of the tube 23, and the flow of the introduced gas is not uniform.
[0009]
Accordingly, the amount of oxygen in the atmosphere in the tube 23 exhausted from the exhaust line is not equal to the amount of oxygen in the atmosphere sucked from the tube from the suction line 10, and the oxygen concentration in the tube is accurately measured. There is a problem that you can not.
[0010]
Further, even if it is attempted to replace the air staying in the suction line 10 with nitrogen gas for maintenance (furnace replacement, etc.), since there is no replacement means, it takes a very long time to replace the nitrogen in the suction line 10 when the apparatus is started up. There is a problem of reducing the operating rate.
[0011]
Accordingly, it is an object of the present invention to provide a lamp annealing apparatus that can uniformly measure the residual oxygen concentration by making the exhaust flow of the atmosphere in the furnace uniform, and can replace the suction line by gas alone.
[0012]
[Means for Solving the Problems]
The present invention includes a furnace that houses a wafer and includes a door for loading and unloading the wafer 25 at one end and a gas introduction line for introducing an inert gas to the other end, and a furnace disposed around the furnace 3. A heating lamp for heating the wafer housed in the furnace, an in-furnace exhaust line connected to the furnace near the door at one end of the furnace and exhausting the atmosphere in the furnace, and branched from the in-furnace exhaust line A suction pump connected to the suction line, an oxygen concentration measuring device provided in the middle of the suction line, a mass flow controller for controlling the flow rate of the inert gas supplied to the gas introduction line, and the oxygen concentration the controls the cans mass flow - - heated by the signal measuring instrument control - a control unit 8 for controlling the La, via the stop valve and said suction line the gas inlet line Binding to Pas - and a Jirain Ranpuani - providing Le device.
[0013]
The present invention also includes a furnace for storing a wafer and having a door for carrying in and out of the wafer 25 at one end and a gas introduction line for introducing an inert gas at the other end, and an outer periphery of the furnace 3. A heating lamp for heating the wafer housed in the furnace, an in-furnace exhaust line connected to the furnace near the door at one end of the furnace and exhausting the atmosphere in the furnace, and a branch from the in-furnace exhaust line A suction pump connected to the suction line, an oxygen concentration measuring device provided in the middle of the suction line, a mass flow controller for controlling the flow rate of the inert gas supplied to the gas introduction line, and A lamp having a control unit 8 for controlling the heating sequence and controlling the mass flow controller by a signal from an oxygen concentration measuring device, and a stop valve for sealing the suction line. Two - to provide Le devices.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Next, the present invention will be described with reference to the drawings.
[0015]
FIG. 1 is a schematic cross-sectional view showing a configuration of a lamp annealing apparatus according to an embodiment of the present invention. As shown in FIG. 1, the lamp annealing apparatus includes a furnace 3 that houses a wafer 25 and includes a door 4 for loading and unloading the wafer 25 at one end and a gas introduction line 5 connected to the other end. A heating lamp 2 that heats the wafer 25 that is disposed in the outer periphery of the furnace 3 and that is housed in the furnace 3, a chamber 1 that encloses the outer periphery of the furnace 3 and the heating lamp 2, and a suction line 10 that is branched to the furnace exhaust line 6. A suction pump 14 for exhausting the atmosphere in the furnace 3 through, an oxygen concentration measuring device 13 provided in the middle of the suction line 10, a gas flow controller 7 for controlling the flow rate of the process gas in the gas introduction line 5, A control unit 8 for controlling the heating sequence and controlling the mass flow controller 7 by a signal from the oxygen concentration measuring device 13 is provided.
[0016]
Further, a purge line 15 for branching from the gas introduction line 5 and having a stop valve 11 in the middle and for purging the process gas 5 in the suction line 10 is provided so that the atmosphere of the suction line 10 can be replaced with a process gas. Is desirable. Furthermore, it is desirable to provide a pressure gauge 17 for measuring the pressure in the furnace 3 in the furnace exhaust line 6 near the furnace 3. On the other hand, preferably, an on-off valve 16 and a damper 18 for adjusting the exhaust capacity of the furnace exhaust line 6 are provided in the middle of the piping of the furnace exhaust line 6. Note that it is desirable to use nitrogen gas, which is inexpensive, as the process gas.
[0017]
Next, the operation of the lamp annealing apparatus will be described. First, the door 4 is opened and the wafer 25 is carried into the furnace 3. At this time, the on-off valve 16 is opened so that outside air does not enter the furnace 3, and the vicinity of the inlet of the furnace 3 is exhausted by the furnace exhaust line 6. And if the wafer 25 is mounted in the predetermined position in the furnace 3, the door 4 will be closed and the furnace 3 will be sealed.
[0018]
Next, the stop valve 12 is opened, and nitrogen gas whose flow rate is adjusted in the mass flow controller 7 is introduced into the furnace 3 through the gas introduction line 5. The introduced nitrogen gas is exhausted together with the air in the furnace 3 by the in-furnace exhaust line 6 and the suction pump 14 of the suction line 10. At this time, if the pointer of the pressure gauge 17 indicates the negative pressure in the furnace, the mass flow controller 7 is adjusted to increase the flow rate of the nitrogen gas so that the pressure in the furnace 3 becomes close to the positive pressure. To do. If the pressure is higher than a predetermined pressure, the opening of the damper 18 is adjusted to reduce the exhaust flow rate in the furnace exhaust line 6 so that the pressure becomes constant.
[0019]
Nitrogen gas introduced with the passage of time flows in one direction, and the atmosphere in the furnace 3 is replaced. Oxygen contained in the gas sucked into the suction line 10 is measured by the oxygen concentration measuring device 13. When the oxygen concentration falls below a predetermined value, the control unit 8 starts the heating sequence, the heating lamp 2 is turned on, the wafer 25 is heated, and the annealing process is started.
[0020]
By adopting a structure in which the suction line 10 is branched from the in-furnace exhaust line 6 in this way, the introduced nitrogen gas and the air in the furnace 3 uniformly flow to the door 4 side. 3 is exhausted by an in-furnace exhaust line 6 attached to a furnace port near the door 4. Accordingly, the oxygen concentration of the atmosphere exhausted from the furnace 3 is different from the case where the gas flows into the suction line 10 branched to the furnace exhaust line 6 and sucks only the vicinity of the wafer 25 in the furnace described in the section of the prior art. Can be measured accurately.
[0021]
The suction pump 14 desirably has the same performance as the exhaust pump provided in the in-furnace exhaust line. When the replacement exhaust operation proceeds to some extent and the oxygen concentration in the exhaust gas becomes low, the on-off valve 16 is closed and the exhaust through the furnace exhaust line 6 is stopped, and the replacement exhaust operation in the furnace 3 is performed only by the suction line 10. For example, all the exhausted gas passes through the suction line 10 and there is an advantage that the residual oxygen in the furnace 3 can be measured more accurately.
[0022]
Since this lamp annealing apparatus is provided with a purge line 15 for connecting the gas introduction line 5 and the suction line 10 via the stop valve 11, it is easy to replace nitrogen in the suction line 10 which could not be done conventionally. it can.
[0023]
FIG. 2 is a schematic cross-sectional view showing a configuration of a lamp annealing apparatus according to another embodiment of the present invention. As shown in FIG. 2, this lamp annealing apparatus is provided with stop valves 19 and 20 for sealing the suction line 10 in place of the nitrogen gas purge line 15 in the above-described embodiment.
[0024]
That is, when the first annealing process is performed, the stop valves 19 and 20 are opened, and the atmosphere in the furnace 3 is replaced with nitrogen gas. At the same time, the atmosphere in the suction line 10 is also replaced with nitrogen gas. Then, the stop valves 19 and 20 are closed and the suction line 10 is sealed. As a result, the suction line 10 is maintained in a state filled with nitrogen gas, and after the maintenance of the furnace 3, the gas replacement of the suction line 10 necessary at the time of start-up becomes unnecessary.
[0025]
【The invention's effect】
As described above, according to the present invention, the suction line for measuring the oxygen concentration is the same exhaust line as the exhaust line in the furnace. The oxygen contained in the gas is uniform. As a result, the oxygen concentration can be accurately measured, thereby improving the quality of the annealed wafer.
[0026]
Further, by providing a means for replacing the gas in the suction line, the gas replacement in the suction line after maintenance can be completed in a short time, so that the operating rate of the apparatus is improved.
[Brief description of the drawings]
FIG. 1 is a schematic cross-sectional view showing a configuration of a lamp annealing apparatus according to an embodiment of the present invention.
FIG. 2 is a schematic cross-sectional view showing a configuration of a lamp annealing apparatus according to another embodiment of the present invention.
FIG. 3 is a view showing an example of a conventional lamp annealing apparatus.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Chamber 2 Heating lamp 3 Furnace 4 Door 5 Gas introduction line 6 Furnace exhaust line 7 Mass flow controller 8 Control part 10 Suction line 11, 12, 19, 20 Stop valve 13 Oxygen concentration measuring device 14 Suction pump 15 Jiline 16 On-off valve 17 Pressure gauge 18 Damper

Claims (6)

A furnace that houses a wafer and has a door for carrying in and out of the wafer 25 at one end and a gas introduction line that introduces an inert gas to the other end, and a furnace disposed around the furnace 3 and housed in the furnace. A heating lamp for heating the wafer, a furnace exhaust line connected to the furnace near the door at one end of the furnace and exhausting the atmosphere in the furnace, and a suction line branched from the furnace exhaust line A suction pump, an oxygen concentration measuring device provided in the middle of the suction line, a mass flow controller for controlling the flow rate of the inert gas supplied to the gas introduction line, and a signal of the oxygen concentration measuring device the controls the cans mass flow - - heated by control - a control unit 8 for controlling the La, Pa connecting the said suction line the gas introduction line via a stop valve Le device - Ranpuani, characterized in that it comprises a Jirain. A furnace that houses a wafer and has a door for carrying in and out of the wafer 25 at one end and a gas introduction line that introduces an inert gas to the other end, and a furnace disposed around the furnace 3 and housed in the furnace. A heating lamp for heating the wafer, a furnace exhaust line connected to the furnace near the door at one end of the furnace and exhausting the atmosphere in the furnace, and a suction line branched from the furnace exhaust line A suction pump, an oxygen concentration measuring device provided in the middle of the suction line, a mass flow controller for controlling the flow rate of the inert gas supplied to the gas introduction line, and a signal of the oxygen concentration measuring device the controls the cans mass flow - - heated by control - a control unit 8 for controlling the La, characterized in that it comprises a stop valve to entrap the suction line lamp Two - Le devices. The lamp annealing apparatus according to claim 1 or 2, wherein the inert gas is nitrogen gas. The lamp annealing apparatus according to any one of claims 1 to 3, further comprising a pressure gauge for measuring a pressure in the furnace. The lamp annealing apparatus according to any one of claims 1 to 4, further comprising an on-off valve that shuts off the furnace exhaust line. The lamp annealing apparatus according to any one of claims 1 to 5, further comprising an exhaust flow rate adjusting mechanism for adjusting an exhaust flow rate of the exhaust line in the furnace.

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