Electric heating – Heating devices – Combined with container – enclosure – or support for material...
Reexamination Certificate
1997-10-31
2002-02-05
Paik, Sang (Department: 3742)
Electric heating
Heating devices
Combined with container, enclosure, or support for material...
C118S725000
Reexamination Certificate
active
06344632
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a round heating plate used in a heating chamber for heating a semiconductor wafer to a predetermined temperature. The present invention also relates to a heating chamber for semiconductor device manufacturing, in which a pair of round heating plates is located so as to be concentric with a pair of wafers when the wafers are installed in the heating chamber, in order to heat the wafers uniformly.
2. Background of the Related Art
In semiconductor device manufacturing, a wafer undergoes several important heat treatments, usually for purposes such as defect removal, active device fabrication and interconnect formation.
Thermal treatments are divided into classifications such as high pressure oxidization, low temperature processing and short time, high temperature processing.
A Rapid Thermal Processing System (RTP) is generally used for short time, high temperature processing. The RTP may use either a single zone heater such as a bell jar type, or a dual wafer system. A dual wafer system is illustrated in FIG.
1
and
FIG. 2
, which includes a heating chamber
1
and a robot arm
3
.
To obtain uniform heating of the wafer in the single zone heater, the inside of the chamber should closely approximate a black body, and for this, the length and width should be large. Due to the impossibility of constricting a chamber with infinite dimensions, temperature varies according to the location of the wafer in the chamber.
In the case of the dual wafer system, two heating plates
2
are secured to a housing
1
of the heating chamber, so as to define a space where an upper wafer
4
and a lower wafer
4
′ are heated simultaneously. The heating plates
2
have a perfect square shape as shown in FIG.
3
. Therefore, it is impossible to heat the wafers
4
and
4
′ evenly, and it is hard to form a layer on each wafer uniformly.
As shown in
FIGS. 4 and 5
, when the wafers
4
and
4
′ are heated to a specified temperature, for example either 760° C. or 820° C. in a nitrogen atmosphere, the temperature at the center of each wafer
4
,
4
′ and the temperatures at other locations on the wafer may be different. The temperature distributions on wafers
4
,
4
′ heated with a square heating plate to 760° C. and 820° C. are shown in
FIGS. 4 and 5
, respectively. As can be seen from
FIGS. 4 and 5
, the temperature deviates from the center of the wafer to the edge of the wafer. Temperature deviations measured front to back and left to right can be seen by following the solid and dotted lines connecting the open circles and triangles for the upper wafer
4
, and connecting the solid circles and triangles for the lower wafer
4
′. Therefore, it is undesirable to heat a round wafer
4
with a square heating plate
2
.
SUMMARY OF THE INVENTION
Accordingly, the present invention is directed to a round heating plate for use in the heating chamber for semiconductor device manufacturing, which heats the wafer evenly. The present invention is also directed to a heating chamber in which a pair of round heating plates have been secured, forming a space between the heating plates into which a pair of wafers is installed for heating. The round heating plate for use in a heating chamber for semiconductor device manufacturing provides for formation of uniform layers on the surface of the wafer through uniform heating of the wafer.
Additional features and advantages of the invention will be set forth in the description which follows, and in part will be apparent from the description, or may be learned through practice of the invention. The objectives and other advantages of the invention will be realized and attained by the structure, particularly pointed out in the written description and claims hereof as well as the appended drawings.
To achieve these and other advantages in the dual wafer system heating chamber, where the wafer is heated, and in accordance with the purpose of the present invention as embodied and broadly described, the round heating plate for use in a heating chamber for semiconductor device manufacturing has the same shape as the wafer to be heated.
The round heating plate can be a resistance heating plate which heats the wafer through electrical resistance heating. The round heating plate is located such that the wafer is concentric with the heating plate during heating. The diameter of the round heating plate is preferably 1.1 to 1.6 times that of the wafer.
The round heating plate may comprise one small diameter round heating plate and multiple ring-shaped heating plates arranged concentrically, in which case an inner surface of the inner-most ring-shaped heating plate is adjacent to an outer surface of the small diameter round heating plate.
Ideally, the ring-shaped heating plate should comprise two to six separate ring-shaped heating plate, wherein the ring-shaped heating plate are arranged so that the outer surface of each ring-shaped heating plate is adjacent to the inner surface of the next larger ring-shaped heating plate.
In the round heating plates and ring-shaped heating plates, temperature can be controlled using variable resistors.
It is to be understood that both the foregoing general description and the following detailed description are intended to provide further explanation of the invention as claimed.
REFERENCES:
patent: 4926025 (1990-05-01), Wilhelm
patent: 5059770 (1991-10-01), Mahawili
patent: 5294778 (1994-03-01), Carman et al.
patent: 5635093 (1997-06-01), Arena et al.
patent: 5753891 (1998-05-01), Iwata et al.
Lee Jung-kyu
Yu Seung-il
Paik Sang
Volentine & Francos, PLLC
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