Semiconductor device manufacturing: process – Coating of substrate containing semiconductor region or of... – Insulative material deposited upon semiconductive substrate
Reexamination Certificate
2000-06-21
2002-05-07
Everhart, Caridad (Department: 2825)
Semiconductor device manufacturing: process
Coating of substrate containing semiconductor region or of...
Insulative material deposited upon semiconductive substrate
C438S622000, C438S789000
Reexamination Certificate
active
06383949
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method of forming an ozonetetraethylorthosilicate (O
3
-TEOS) oxide film, and to apparatus for depositing material, such as O
3
-TEOS oxide, on a substrate.
2. Description of the Related Art
As of recent, TEOS oxide films are being widely used as interlayer dielectric films and planarization films of semiconductor devices. O
3
-TEOS oxide films, which comprise a TEOS film formed using ozone (O
3
) as a catalyst, are also being widely used for such applications.
General TEOS films have a step coverage superior to that of conventional exhibits a smooth shape at the edges of an underlying pattern layer and excels in filling the gap between adjacent portions of the pattern layer. Moreover, O
3
-TEOS films have excellent characteristics when serving as planarization films. However, when TEOS films are formed on an underlying film, they may exhibit an abnormal growth pattern or poor surface characteristics, depending on the type of material or pattern of the underlying film. That is, the dependence of the quality of O
3
-TEOS films upon their underlying films includes pattern dependence (or pattern sensitivity) and base material dependence. Pattern dependence refers to the fact that O
3
-TEOS deposits relatively slowly over dense patterns and much quicker over sparse patterns; consequently, an O
3
-TEOS film typically will have a non-uniform thickness when deposited over an underlying pattern layer. Base material dependence refers to the fact that O
3
-TEOS can grow irregularly or acquire an excessive surface roughness depending on the material of its underlying film, independently of the density of patterns of the underlying film.
The present invention particularly relates to the base material dependence of O
3
-TEOS films. The base material dependence of O
3
-TEOS films will now be described in further detail with reference to FIG.
1
.
As shown in this figure, a layer
13
having a predetermined pattern is formed on a substrate
11
(a silicon substrate or a layer of material already formed on a substrate). A lower film
15
of a material for which O
3
-TEOS exhibits base dependence is then formed on the resultant substrate. An O
3
-TEOS film
17
is then formed on the lower film
15
. As shown in
FIG. 1
, the O
3
-TEOS film
17
forms unevenly on the lower film, and has an extremely rough surface due to abnormal growth. Here, it must be noted that the high surface roughness is not due to the pattern of the underlying layer
13
but due to the material of the lower film
15
on which the O
3
-TEOS film
17
is formed. In fact, even if the O
3
-TEOS film
17
were formed on a flat underlying layer
13
instead of one having a stepped configuration as shown in
FIG. 1
, only the pattern dependence of the O
3
-TEOS film
17
would be reduced and the film would still exhibit base dependence problems similar to those described above. Films for which an O
3
-TEOS film has base material dependence include a thermal oxide film, a high temperature oxide (HTO) film, a nitride film formed by chemical vapor deposition (CVD), and a TEOS film formed by plasma enhanced CVD (PE-CVD). Finally, it should be noted that the cause of base material dependence is assumed to be some characteristic of the underlying film, e.g., hydrophilicity/hydrophobicity, or the existence of an ON group, but such a cause has not yet been ascertained with a high degree of certainty.
Regardless, base material dependence can be eliminated by the following three proposed methods.
First, a lower film
15
of a material for which the O
3
-TEOS film
17
has no base material dependence can be formed on the substrate just prior to the depositing of the O
3
-TEOS film
17
. For example, this material can be an oxide deposited by PE-CVD using a silane gas as a source gas, or a nitride deposited by PE-CVD (see U.S. Pat. No. 5,804,498 entitled “Method Of Making An Underlayer To Reduce Pattern Sensitivity Of Ozone-TEOS”). Although this patent refers to pattern sensitivity, strictly speaking, what has been eliminated by the nitride or oxide formed by PE-CVD is base material dependence. However, since the PE-CVD oxide or nitride is formed by plasma deposition, the quality of its material is poor. Furthermore, PE-CVD is a complicated method to perform, and it is difficult to produce an oxide or nitride layer having a uniform thickness using PE-CVD. Therefore, the use of these materials as the film underlying the O
3
-TEOS film makes for unreliable semiconductor devices.
Secondly, the underlying film on which the O
3
-TEOS film has base material dependence may be plasma-treated for a predetermined period of time under an N
2
or NH
3
gas atmosphere, before the O
3
-TEOS is deposited thereon (see K. Fujino, Y. Nishimoto, N. Tokumasu, and K. Maeda, “Surface Modification of Base Materials for TEOS/O
3
Atmospheric Pressure Chemical Vapor Deposition”, J. Electrochem. Soc., Vol. 139, No. 6, June 1999). The surface roughness of the O
3
-TEOS film
18
is significantly kept in check in this way, as shown in FIG.
2
. However, plasma treatment is another complex processing method, and detracts from the productivity of the overall manufacturing process.
Thirdly, the O
3
-TEOS film may be deposited on the substrate at a high temperature. That is, O
3
-TEOS films are typically formed at about 400° C. However, it has been shown that an O
3
-TEOS film formed at about 500° C. has an excellent surface roughness. Unfortunately, this method is problematic in that the deposition rate is very slow and thus the method is associated with poor productivity. For example, when O
3
-TEOS is deposited on a bare silicon substrate at 400° C., the deposition rate is approximately 800 Å/min, but at 500° C., the deposition rate is only about 150 Å/min. Therefore, this third method is not suitable for mass production.
SUMMARY OF THE INVENTION
Accordingly, a first object of the present invention is to provide a simple method of depositing O
3
-TEOS, in which base material dependence is eliminated, and film quality and productivity are guaranteed.
The second object of the present invention is to provide a deposition apparatus which is particularly suitable for performing the above-described O
3
-TEOS deposition method and can also be used to deposit other materials on a substrate.
To achieve the first object, the present invention provides a method of forming an O
3
-TEOS oxide film which includes depositing a first portion of O
3
-TEOS oxide on a lower film, at such a high temperature that the characteristics of the O
3
-TEOS oxide film are not base material dependent on the lower film, and then depositing a second portion of O
3
-TEOS oxide on the first portion of O
3
-TEOS oxide at a low temperature which allows the deposition to occur at a high rate.
The temperature at which the first portion of the O
3
-TEOS oxide film is formed is preferably within a range of 450 to 600° C., and the temperature at which the second portion of the O
3
-TEOS oxide film is preferably within a range of 360 to 440° C. Also, such temperature conditions can be produced as a series step-wise temperature changes or as a continuously decreasing temperature.
Also, the deposition steps are preferably performed in situ to enhance productivity.
To achieve the second object, the present invention provides a deposition apparatus which includes at least two susceptors, each of which is configured to support a wafer on which a layer is to be formed and comprises a heater for heating the wafer, at least one shower head for directing source gases toward the wafers, and a robot arm for loading the susceptors with wafers, transferring the wafers between the susceptors, and unloading completed wafers from the susceptors. The temperature of at least one of the heaters can heat the wafer supported on its susceptor to a temperature different from that/those provided by the other heater/heaters.
To achieve the second object, the present invention also provides a deposition apparatus which includes a conv
Kim Do-hyung
Na Dong-geun
Everhart Caridad
Samsung Electronics Co,. Ltd.
Volentine & Francos, PLLC
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