Coating apparatus – Gas or vapor deposition
Reexamination Certificate
2001-07-16
2004-10-05
Lund, Jeffrie R. (Department: 1763)
Coating apparatus
Gas or vapor deposition
C156S345330, C156S345340
Reexamination Certificate
active
06800139
ABSTRACT:
TECHNICAL FIELD
The present invention generally relates to a film deposition apparatus and method, and, more particularly, to a film deposition apparatus and method for depositing a PZT film on a semiconductor wafer.
BACKGROUND ART
A PZT film can be obtained as a crystal film of Pb(Zr
1-x
Tix)O
3
having a perovskite structure by making an organometallic material gas react with an oxidant gas such as NO
2
gas in a chemical vapor deposition (CVD) process apparatus. The organometallic material gas contains Pb(DPM)
2
(Bisdipivaloyl-methanatolead : Pb(C
11
H
19
O
2
)
2
), Zr (t-OC
4
H
9
)
4
(Tetratertiary-butoxyzirconium) and Ti(I-OC
3
H
7
)
4
(Tetraisopropoxy-titanium). Pb refers to lead, Zr refers to zirconium, and Ti refers to titanium. The PZT film has attracted great attention as a memory capacitor material of a second-generation planar stack type FeRAM.
Generally, in order to deposit an oxide film such as a PZT film in a crystal state, a wafer or substrate on which the oxide film is deposited must be heated to a temperature as high as about 600° C. However, in a case in which a structure having weakness against heat is previously formed on the wafer or substrate, the film deposition process must be performed by a two-stage process including a process of forming a crystalline nucleus and a process of growing the crystal so as to decrease the process temperature of the film deposition process. The degrees of vacuum appropriate for the two processes are not always equal to each other. Thus, it is required to perform a low vacuum process and a high vacuum process by using a single chamber. However, since there is no showerhead, which can be used for both the high vacuum process and the low vacuum process, the two-stage process must be performed by using two different chambers.
When an organometallic material (MO) is used in a gaseous state, the organometallic material gas must be heated due to its low vapor pressure. Accordingly, if the organometallic material gas meets an oxidant gas within a supply pipe, the organometallic material gas immediately reacts with the oxidant gas within the supply pipe, which results in deposition or formation of particles within the supply pipe. In order to eliminate such a problem, when the organometallic material gas is used, a post mix type showerhead is normally used so as to mix the organometallic material gas with the oxidant gas after exiting the showerhead. However, it is difficult to eliminate leakage between the organometallic material gas and the oxidant gas in the showerhead due to the construction of the showerhead. That is, there is a small air gap formed between the passages of the organometallic material gas and the oxidant gas due to the fabrication method of the showerhead. Thus, a gas leakage occurs between the areas of the organometallic material gas and the oxidant gas in the showerhead, which results in deposition of the oxidized organometallic material or generation of particles of the oxidized organometallic material.
DISCLOSURE OF INVENTION
It is a general object of the present invention to provide an improved and useful film deposition apparatus and method in which the above-mentioned problems are eliminated.
A more specific object of the present invention is to provide a film deposition apparatus and method which can form a PZT film at a high deposition rate under a low temperature by using a single showerhead throughout the deposition process.
In order to achieve the above-mentioned objects, there is provided according to one aspect of the present invention a film deposition apparatus for depositing a film on an object to be processed, the film deposition apparatus comprising: a process chamber accommodating the object therein; process gas supplying means for supplying process gases including a raw material gas and an oxidant gas; evacuating means for evacuating the process gases from the process chamber so as to maintain the process chamber to be at a predetermined vacuum; and process gas introducing means for introducing the process gases supplied from the process gas supplying means into the process chamber, wherein the process gas introducing means is configured and arranged to inject the process gases to an entire surface of the object, a gas injection surface from which the process gases are injected being divided into an inner zone covering a center portion of the object and an outer zone surrounding the inner zone; and the process gas supplying means selectively supplies the process gases to the process gas introducing means so that the raw material gas is separately injected from the inner zone and the outer zone, and the oxidant gas is separately injected from the inner zone and the outer zone.
According to the above-mentioned invention, crystalline nucleuses can be efficiently formed on the object to be processed such as a wafer by injecting the raw material gas to the center portion of wafer and the oxidant gas to the peripheral portion of the wafer surrounding the center portion while maintaining the process chamber at a high vacuum. After the crystalline nucleuses are formed on the wafer, the crystal of the film can be grown at a high rate by injecting the raw material gas and the oxidant gas uniformly to the entire surface of the wafer at a relatively low temperature while maintaining the process chamber at a relatively low vacuum.
In the film deposition apparatus according to the present invention, the process gas supplying means may include switching means for switching the supply of the raw material gas to the process gas introducing means so that the raw material gas is selectively injected from either the inner zone alone or both the inner zone and the outer zone and the oxidant gas is selectively injected from either the outer zone alone or both the inner zone and the outer zone.
In one embodiment of the present invention, the process gas supplying means may include a first raw material gas supply passage supplying the raw material gas to the inner zone, a second raw material gas supply passage supplying the raw material gas to the outer zone, a first oxidant gas supply passage supplying the oxidant gas to the inner zone and a second oxidant gas supply passage supplying the oxidant gas to the outer zone; and the switching means may include a first open/close valve provided to the first raw material gas supply passage, a second open/close valve provided to the second raw material gas passage, a third open/close valve provided to the first oxidant gas supplying passage and a fourth open/close valve provided to the second oxidant gas supply passage.
Additionally, the raw material gas may be a mixture of a plurality of material gases, and the process gas supplying means may include: a plurality of material gas supplying passages; and an open/close valve provided to one of the material gas supplying passages so that the material gas supplied through the one of the material gas supplying passages is selectively added to the raw material gas.
The process chamber may include a table on which the object is placed; and a vertical moving mechanism for moving the table in a vertical direction so that a distance between the table and the process gas introducing means is changeable. Accordingly, when the film deposition process is performed at a high vacuum so as to form crystalline nucleuses, the distance between the wafer and the shower head can be increased so that the raw material gas and the oxidant gas are uniformly mixed to each other by diffusion, which results in a uniform composition of the deposited film.
The film deposition apparatus according to the present invention may further comprise: pressure detecting means for detecting a pressure of each of the raw material gas and the oxidant gas in said process gas introducing means; dilution gas adding means for adding a dilution gas to one of the raw material gas and the oxidant gas; and dilution gas amount control means for controlling an amount of the dilution gas to be added based on the pressure detected by the pressure detecting means so that th
Matsumoto Kenji
Shinriki Hiroshi
Lund Jeffrie R.
Pillsbury & Winthrop LLP
Tokyo Electron Limited
LandOfFree
Film deposition apparatus and method does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Film deposition apparatus and method, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Film deposition apparatus and method will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3305225