Patent Application
20080020549
The foregoing and other objects, aspects, features, and advantages of the invention will become more apparent and may be better understood by referring to the following description taken in conjunction with the accompanying drawings, in which:
The present invention will be more completely understood through the following detailed description, which should be read in conjunction with the attached drawings. In this description, like numbers refer to similar elements within various embodiments of the present invention. Within this detailed description, the claimed invention will be explained with respect to preferred embodiments. However, the skilled artisan will readily appreciate that the methods and systems described herein are merely exemplary and that variations can be made without departing from the spirit and scope of the invention.
In the process of manufacturing semiconductor chips, an essential step is to oxidize the surface of the semiconductor wafer as described above. The invention disclosed herein relates to an apparatus and a method for forming an oxide layer on semiconductor wafer by using a combination of ultraviolet light and heat. In brief overview, a silicon wafer is exposed to ozone gas so that a chemical reaction takes place on the surface of the silicon wafer forming an oxide layer on the surface. Ultraviolet radiation is used to convert oxygen gas to ozone gas, and the silicon wafer is heated in the process to accelerate the chemical reaction.
Referring to
In operation, a silicon wafer 102 is first positioned in the chamber 100 by a robotic arm 122. The chamber 100 is then sealed except for the oxygen gas inlet 112 and the outlet 114. Oxygen gas enters the chamber 114 through the oxygen gas inlet 112. Once in the chamber 112, oxygen gas is ionized by ultraviolet radiation from the ultraviolet source 104 to form ozone. As ozone gas fills up the chamber 100 and surrounds the silicon wafer 102, a chemical reaction takes place on the surface of the silicon wafer 102. The reaction forms an oxide layer (not illustrated) on the surface of the silicon wafer 102. During the process, the silicon wafer 102 is simultaneously heated by the infrared source 110 at the bottom of the chamber 100 to accelerate the formation of the oxide layer.
To prevent infrared rays from reaching the ultraviolet source 104 and heating it, the ultraviolet transparent filter 106, transparent substantially only to ultraviolet radiation, is positioned between the chamber 100 and the ultraviolet source 104. Similarly, the infrared transparent filter 108, transparent only to infrared rays, blocks all ultraviolet radiation and prevents the radiation from reaching the infrared source 110. In one embodiment, the infrared source 110 is a set of infrared lamps 126, which is a strong infrared source. Here, the infrared transparent filter 108 also serves as a heat conductor that helps to distribute the heat from the multiple lamps 126 evenly on the silicon wafer 102.
As illustrated in
As illustrated in
The ultraviolet source may overheat as the process carries on. In one embodiment, the ultraviolet source is a tubular ultraviolet lamp located in a nitrogen gas chamber 124 as shown in
The method of forming an oxide layer on a silicon wafer involves a chemical reaction of the silicon wafer and ozone gas. To start the reaction, the silicon wafer is moved by a robotic arm into the chamber where the silicon wafer is heated to an optimal temperature at which the chemical reaction can be most efficiently carried out. In one embodiment, the heating is achieved by exposing the silicon wafer under infrared rays from multiple infrared lamps (see
Variations, modifications, and other implementations of what is described herein will occur to those of ordinary skill in the art without departing from the spirit and scope of the invention as claimed. Accordingly, the invention is to be defined not by the preceding illustrative description but instead by the spirit and scope of the following claims.
