Electric heating – Heating devices – Combined with container – enclosure – or support for material...
Reexamination Certificate
2001-02-16
2003-02-11
Walberg, Teresa (Department: 3742)
Electric heating
Heating devices
Combined with container, enclosure, or support for material...
C219S405000, C219S411000, C118S724000, C118S050100, C392S416000, C392S418000
Reexamination Certificate
active
06518547
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a substrate heat treatment apparatus irradiating a substrate such as a semiconductor wafer, a glass substrate for a photomask, a glass substrate for a liquid crystal display or a substrate for an optical disk (hereinafter simply referred to as “substrate”) for performing heat treatment.
2. Description of the Background Art
As refinement of a semiconductor device or the like is strictly required, a rapid heat treatment process referred to as an RTP (rapid thermal process) is watched with interest as one of heating steps for a substrate.
FIG. 17
is a longitudinal sectional view of a conventional RTP apparatus. In the RTP, the following treatment is performed with this apparatus: Lamps
91
a,
91
b
and
91
c
are employed as heating sources, and treatment gas (e.g., nitrogen gas or oxygen gas) responsive to the treatment process is supplied into a treatment chamber
90
from a gas inlet port
90
a
for keeping the treatment chamber
90
in such a gas atmosphere, heating a substrate W to a desired temperature (up to about 1200° C.) in order of seconds, holding the substrate W at the temperature for a desired time (several 10 seconds) and thereafter turning off the lamps
91
a
to
91
c
and rapidly cooling the substrate W.
This apparatus, capable of preventing impurities from re-diffusion caused by heat in junction layers of transistors formed on the substrate W and forming an insulator film such as a thin oxide film, can perform treatment which has been hard to implement by conventional long-time high-temperature heat treatment with an electric furnace.
In the conventional apparatus, the cylindrical lamps
91
a
to
91
c
are embedded in a reflector
93
having a cylindrical reflecting surface
95
as shown in
FIG. 17
, in order to apply emitted light to the substrate W with a certain degree of directivity.
In general, however, light emitted from filaments
94
is mainly applied in a direction (hereinafter referred to as “side surface direction”) perpendicular to the longitudinal direction of the filaments
94
, i.e., in the direction (along an X-Y plane) of the cylindrical reflecting surface
95
of the reflector
93
in the apparatus shown in FIG.
17
. In other words, the light is intensely applied toward the side surface direction and extremely weakly applied in the longitudinal direction (Z-axis direction) of the filaments
94
. Therefore, most of the light emitted from the filaments
94
is multiple-reflected in the cylindrical reflecting surface
95
to thereafter outgo from the lower end of the cylindrical reflecting surface
95
. Also in this case, the light mainly outgoes in the side surface direction, and the optical path toward the substrate W may be elongated to attenuate the light, leading to inferior heating efficiency for the substrate W.
Most of the light in the aforementioned side surface direction reaches the cylindrical reflecting surface
95
, to be partially absorbed by the cylindrical reflecting surface
95
. It follows that most of the light reflected by the cylindrical reflecting surface
95
returns to the lamps
91
a,
91
b
and
91
c,
and hence the cylindrical reflecting surface
95
and the lamps
91
a
to
91
c
reserve heat to be deflected due to high temperatures or inhibit the halogen cycle of halogen gas in glass tubes
96
provided in the lamps
91
a
to
91
c,
leading to reduction of the lives of the lamps
91
a
to
91
c.
In the RTP, temperature distribution in the substrate surface (X-Y plane) of the substrate W is desirably uniform. In order to improve temperature uniformity of the substrate W, therefore, radiation thermometers
92
a,
92
b
and
92
c
are provided in correspondence to a center area CA, a middle area MA and an edge area EA respectively, for example, in the substrate surface for measuring the temperatures of the aforementioned areas CA, MA and EA respectively while the plurality of lamps
91
a,
91
b
and
91
c
are provided in correspondence to the areas CA, MA and EA respectively for feedback-controlling power supplied to the lamps
91
a
to
91
c
for the areas CA, MA and EA so that the substrate temperatures on the respective areas CA, MA and EA match with each other.
However, the temperatures of intermediate portions between the center area CA and the middle area MA and between the middle area MA and the edge area EA, for example, are not measured, and these intermediate portions located between the areas CA, MA and EA cannot be selectively temperature-controlled. Therefore, the temperature of the substrate W is ununiform on these intermediate portions. Temperature ununiformity in these intermediate portions is further described.
FIG. 18
is a plan view showing lamp arrangement in the conventional RTP apparatus. This RTP apparatus comprises a lamp group
99
formed by 19 lamp units
98
. Each lamp unit
98
is formed by a lamp
91
and a cylindrical reflecting surface
95
. As shown in
FIG. 18
, the lamp group
99
is in honeycomb arrangement having six lamp units
98
adjacently provided around a single lamp unit
98
. The lamp group
99
is arranged to cover the overall surface of a substrate W with the 19 lamps
91
. The diameter of the substrate W is 200 mm.
In order to heat-treat the substrate W with the lamp group
99
, each lamp
91
is supplied with power to emit light. The light outgoing from each lamp
91
reaches the substrate W directly or after reflected by the cylindrical reflecting surface
95
, to heat the substrate W. At this time, the lamp group
99
is divided into three areas consisting of a center area formed by the centermost lamp
91
, an edge area formed by 12 outermost lamps
91
and a middle area formed by six intermediately located lamps
91
for varying power supply patterns with the areas while rotating the substrate W, thereby ensuring inplane temperature uniformity of the substrate W.
However, the conventional heat treatment apparatus cannot ensure sufficient inplane temperature uniformity despite the aforementioned power supply control for each area and rotation of the substrate W. The reason for this is now described.
FIG. 19
illustrates illuminance distribution on the substrate W with a single lamp
91
. Referring to
FIG. 19
, the left-end position (position of a distance zero) is a position immediately under the lamp
91
in the vertical direction on the substrate W. Symbol RP denotes the radius of the lamp
91
.
While high illuminance is obtained on the position immediately under the lamp
91
, illuminance on the substrate W tends to gradually lower as the distance from this position is increased. In other words, the light emitted from the lamp
91
has downward directivity due to the cylindrical reflecting surface
95
and hence substantially uniform high illuminance is obtained immediately under the lamp
91
(within the range of the diameter of the lamp
91
), while illuminance of the light emitted from the lamp
91
lowers as the horizontal distance (direction parallel to the surface of the substrate W) from the lamp
91
is increased.
On the other hand, the
19
lamps
91
forming the lamp group
99
is arranged in the form of a honeycomb as described above, and it can be said that the
19
lamps
91
are arranged on concentric circles in another point of view. Therefore, the conventional heat treatment apparatus exhibits illuminance distribution shown in
FIG. 20
also when rotating the substrate W.
FIG. 20
illustrates radial illuminance distribution on the substrate W in the conventional heat treatment apparatus. As shown in
FIG. 20
, a certain degree of illuminance is attained in positions on the substrate W under the aforementioned center area, the middle area and the edge area respectively, while illuminance lowers in positions under the intermediate portions between the areas. Each lamp
91
applies a sufficient quantity of light under the center area, the middle area and the edge area to increase illuminance due to the illuminance distribution of the light emitted from each la
Ito Yoshio
Nishihara Hideo
Takahashi Mitsukazu
Dainippon Screen Mfg. Co,. Ltd.
Fuqua Shawntina T.
Ostrolenk Faber Gerb & Soffen
Walberg Teresa
LandOfFree
Heat treatment apparatus does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Heat treatment apparatus, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Heat treatment apparatus will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3168706