Semiconductor device manufacturing: process – Making field effect device having pair of active regions... – Having insulated gate
Reexamination Certificate
2001-09-28
2004-06-08
Pham, Long (Department: 2814)
Semiconductor device manufacturing: process
Making field effect device having pair of active regions...
Having insulated gate
C438S297000, C438S362000, C438S425000, C438S439000, C438S452000
Reexamination Certificate
active
06746908
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a temperature controlling method, a thermal treating apparatus for a semiconductor manufacturing device or the like, and a method for manufacturing a semiconductor device, and in particular, it relates to a temperature controlling method and a thermal treating apparatus for a semiconductor device or the like, and a method for manufacturing a semiconductor device, wherein in order to thermally treat a treatment target, the thermal treating apparatus is divided into a plurality of heating zones, and target temperatures are set for the plurality of heating zones for temperature control so that the target temperatures are corrected using temperatures detected in areas of the treatment target the number of which is larger than the number of the plurality of heating zones.
2. Description of the Related Art
With known thermal treating apparatuses, if, a semiconductor wafer (substrate) as a treatment target is thermally treated for film formation or the like, various temperatures are required which correspond to the types of films formed as a result of the treatment and a fabrication process thereof. Accordingly, during the thermal treatment, the temperature of the treatment target is controlled so as to be as close to the treatment temperature as possible (soaking control method).
FIG. 6
is a diagram showing the structure of a vertical diffusion furnace, which is typical of such thermal treatment apparatuses. The vertical diffusion furnace shown in
FIG. 6
is composed of a soaking pipe
112
and a reaction pipe
113
covered by an outer wall
111
, a heater
114
for heating the inside of the reaction pipe
113
, heater thermocouples
115
for detecting the temperatures of the heater
114
at a plurality of locations thereof, cascade thermocouples
116
for detecting the temperature at locations between the soaking pipe
112
and the reaction pipe
113
, a boat
117
on which a wafer to be subjected to thermal treatment is mounted, and a temperature controller
119
for controlling the amount of operation Z (value of electric power) for the heater
114
on the basis of the temperatures detected by the heater thermocouple
115
and the cascade thermocouple
116
as well as an indicated target temperature Y.
The heater
114
is divided into a plurality of heating zones so as to accurately control the in-furnace temperature (temperature of the reaction pipe
113
). If the heater
114
is divided, for example, into four heating zones as shown in
FIG. 6
, the zones are called U, CU, CL, and L zones (hereinafter these names will be used) respectively from the top to the bottom of the figure. Each of the heating zones has the heater thermocouples
115
and the cascade thermocouples
116
installed therein. In order that the temperatures detected by the cascade thermocouples
116
equal the target temperature, the temperature controller
119
detects the temperatures of the heater thermocouples
115
while calculating the amount of operation Z for the heater
114
in accordance with a given algorithm (PID calculations or the like), thereby adjusting the power value for the heater
114
.
In this manner, the conventional temperature control is executed so that the temperatures detected by the cascade thermocouples
116
equal the target value for the wafer treatment. Accordingly, there may be not a small difference between the temperature at the location of the wafer to be actually treated and the corresponding temperature detected by the cascade thermocouple, thereby degrading the quality of the thermal treatment. Thus, it is necessary to control the temperature of an area closer to the wafer or the temperature of the wafer itself so as to equal the target value for the wafer treatment in order to improve the quality of the thermal treatment. To achieve this, a means is required which detects the temperature of an area closer to the wafer or the temperature of the wafer itself. The detection means includes various methods such as the one of inserting thermocouples into the reaction tube to measure the temperatures of the neighborhoods of the wafer, or estimating the wafer temperatures using a mathematical model. Here, by way of example, a description will be given of a method of using temperature measuring wafers (thermocouple-mounted wafers) each comprising a thermocouple directly installed on a wafer.
FIG. 7
shows an example using the above described thermocouple-mounted wafers. In this case, thermocouple-mounted wafers
118
are arranged so as to correspond to the U, CU, CL, and L zones, the four heating zones. The heater thermocouples
115
and the cascade thermocouples
116
are also installed at locations corresponding to the U, CU, CL, and L zones. The temperatures detected by the thermocouple-mounted wafers
118
are obtained not only by the heater thermocouples
115
and the cascade thermocouples
116
but also by the temperature controller
119
. Further, for the thermocouple-mounted wafers, the location at which the thermocouple is installed and the number of thermocouples installed may depend on the usage thereof. For the thermocouple-mounted wafers
118
in the example described herein, it is assumed that only one thermocouple is installed in the center of the wafer.
FIG. 9
shows an example of the relationship between the temperatures detected by the cascade thermocouples
116
and the thermocouple-mounted wafers
118
, wherein the temperature control is executed so that the temperatures detected by the cascade thermocouples
116
equal the target value for the wafer treatment. In this case, the temperatures (◯) detected by the cascade thermocouples
116
equal the target value, whereas there may be errors between the temperatures (&Dgr;) detected by the thermocouple-mounted wafers
118
and the target value. Further, since the magnitude of the error and the like varies among the heating zones, this constitutes a factor reducing the quality of the thermal treatment. In this case, the errors between the temperatures detected by the thermocouple-mounted wafers
118
and the target temperature for the cascade thermocouples
116
may be used as corrective values for this target temperature. For example, in
FIG. 9
, if the temperature detected by the thermocouple-mounted wafer for the U zone is lower than the target value by 5° C., then this 5° C. can be used as a corrective value for the target temperature for the corresponding cascade thermocouple.
The above described correction increases the temperature detected by the cascade thermocouple
116
for the U zone, above the original target value by 5° C., but the temperature detected by the thermocouple-mounted wafer for the U zone can be made equal to the original target value.
FIG. 10
shows an example of the relationship between the temperatures detected by the cascade thermocouples and the thermocouple-mounted wafers, wherein the correction is executed for all the heating zones. In this case, the temperatures (◯) detected by the cascade thermocouples
116
do not equal the original target value, whereas the temperatures (&Dgr;) detected by the thermocouple-mounted wafers
118
equal the target value. The temperature of wafers to be actually thermally treated equals the target value, so that the quality of the thermal treatment can be improved. In this example, however, even if 5° C. is added to the target value for the cascade thermocouple as a corrective value in order to increase the temperature detected by the thermocouple-mounted wafer
118
by 5° C., the temperature detected by the thermocouple-mounted wafer often fails to actually increase by 5° C., thereby requiring an adjustment operation to be repeated several times.
Furthermore, in the construction shown in
FIG. 7
, the thermocouple-mounted wafers
118
are arranged at the locations corresponding to the heater thermocouples
115
and cascade thermocouples
116
installed for the respective heating zones. In contrast,
FIG. 11
shows an example of the relationship
Nakano Minoru
Tanaka Kazuo
Ueno Masaaki
Yamaguchi Hideto
Hitachi Kokusai Electric Inc.
Louie Wai-Sing
Pham Long
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