Coating apparatus – Gas or vapor deposition – With treating means
Reexamination Certificate
2000-08-25
2001-07-03
Bueker, Richard (Department: 1763)
Coating apparatus
Gas or vapor deposition
With treating means
C118S715000, C118S725000, C118S728000
Reexamination Certificate
active
06254686
ABSTRACT:
BACKGROUND OF THE INVENTION
1) Field of the Invention
The present invention relates to semiconductor processing equipment, more particularly, to a method and apparatus for reducing particle contamination in a semiconductor processing apparatus.
2) Discussion of Related Art
One type of processing apparatus for semiconductor wafers is a single wafer processor in which one wafer at a time is processed in a processing chamber. An example of a single wafer reactor is shown in
FIG. 1. A
susceptor
120
divides a chamber
112
into one portion which is below the susceptor (the lower portion)
124
, and a second portion which is above the susceptor (the upper portion)
122
. The susceptor
120
is generally mounted on a shaft
126
which rotates the susceptor about its center to achieve a more uniform processing of the wafer. A flow of a processing gas, such as a deposition gas
115
, is provided in the upper portion
122
of the chamber. The chamber generally has a gas inlet passage
178
at one side thereof, and a gas exhaust passage
116
at an opposite side to achieve a flow of the processing gas across the wafer. The susceptor
120
is heated in order to heat the wafer to a desired processing temperature. One method used to heat the susceptor is by the use of lamps
134
provided around the chamber and directing their light into the chamber and onto the susceptor
120
. In order to control the temperature to which the wafer is being heated, the temperature of the susceptor is constantly measured. This is often achieved by means of an infrared temperature sensor
136
which detects the infra-red radiation emitted from the heated susceptor.
A problem with this type of processing apparatus is that some of the processing gas, which is often a gas or mixture of gases for depositing a layer of a material on the surface of the wafer, tends to flow around the edge of the susceptor and deposits a layer of the material on the back surface of the susceptor. Since the deposited material is generally different from the material of the susceptor, the deposited layer has an emissivity which is different from that of the ernissivity of the susceptor. Thus, once the layer of the material is deposited on the back surface of the susceptor, the infrared temperature sensor detects a change caused by the change in the emissivity of the surface from which the infra-red radiation is emitted. This change indicates a change in temperature of the susceptor which actually does not exist.
One technique which has been used to prevent the problem of deposits on the back surface of the susceptor is to provide a flow of an inert gas
121
, such as hydrogen, into the lower portion of the chamber at a pressure slightly greater than that of the deposition gas in the upper portion of the chamber. One apparatus for achieving this is described in the application for U.S. Patent of Roger N. Anderson et al., Ser. No. 08/099/977, filed Jul. 30, 1993, entitled “Gas Inlets For Wafer Processing Chamber”. Since the inert gas in the lower portion of the chamber is at a higher pressure, it will flow around the edge of the susceptor from the lower portion of the chamber and into the upper portion of the chamber. This flow of the inert gas prevents the flow of the deposition gas
115
into the lower portion of the chamber. Unfortunately, however, as the purge gas flows from the lower portion of the chamber to the upper portion of the chamber in order to exit through the exhaust passage
116
located in the upper portion
122
of chamber
122
, it carries metal contaminants from the lower portion of the chamber into the upper portion, resulting in contamination of wafers being processed.
Another problem associated with the processing apparatus of
FIG. 1
is that as deposition gas
115
exits the chamber through exhaust passage
116
, the deposition gas cools and condenses to form deposits
114
within the exhaust passage
116
. Deposition gas cools because the apparatus of
FIG. 1
is a “cold wall reactor”. That is, the sidewall of the deposition chamber is at a substantially lower temperature than is susceptor
120
(and wafer) during processing because the sidewall is not directly irradiated by lamp
134
due to reflectors
135
and because cooling fluid is circulated through the sidewall. Since the sidewall and the exhaust outlet passage are at a lower temperature, the deposition gas heated by susceptor
120
cools while in the passage and forms deposits
114
therein. These deposits
114
can find their way back into chamber
112
and onto the wafer being processed. Deposits
114
can detrimentally affect film quality and uniformity which can result in a substantial decrease in device yield.
Thus, what is desired is a method and apparatus which can reduce the formation of deposits in the exhaust passage and which can reduce metal contamination from the lower portion of the chamber.
SUMMARY OF THE INVENTION
The present invention is a single wafer reactor having a vented lower liner for heating exhaust gas. The apparatus of the present invention includes a reaction chamber. A wafer support member which divides the chamber into an upper and lower portion is positioned within the chamber. An exhaust channel is formed in the sidewall of the reaction chamber to exhaust gas from within the chamber. Deposition gas is exhausted through an exhaust passage located between the upper portion of the chamber and the exterior sidewall of the deposition chamber. A high flow rate of heated purge gas is exhausted from the lower portion of the chamber through a vent located between the lower portion of the chamber and the exhaust passage. The high flow rate of heated purge gas into the exhaust passage prevents the exhausted deposition gas from condensing in the exhaust passage and forming deposits therein.
REFERENCES:
patent: 4976996 (1990-12-01), Monkowski et al.
patent: 5133284 (1992-07-01), Thomas et al.
patent: 5275976 (1994-01-01), Moslehi
patent: 5326725 (1994-07-01), Sherstinsky et al.
patent: 5383971 (1995-01-01), Selbrede
patent: 5445677 (1995-08-01), Kawata et al.
patent: 5447570 (1995-09-01), Schmitz et al.
patent: 5516367 (1996-05-01), Lei et al.
patent: 5578532 (1996-11-01), van de Ven et al.
patent: 5614247 (1997-03-01), Barbee et al.
patent: 5871586 (1999-02-01), Crawley et al.
patent: 4142877 (1992-07-01), None
patent: 60-273819 (1985-05-01), None
patent: 61-065880 (1986-03-01), None
patent: 0445596 (1991-09-01), None
patent: 0606751 (1994-07-01), None
Carlson David K.
Comita Paul B.
Fan Doria W.
Ranganathan Rekha
Riley Norma B.
Applied Materials Inc.
Blakely & Sokoloff, Taylor & Zafman
Bueker Richard
LandOfFree
Vented lower liner for heating exhaust gas from a single... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Vented lower liner for heating exhaust gas from a single..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Vented lower liner for heating exhaust gas from a single... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2554015