Adhesive bonding and miscellaneous chemical manufacture – Differential fluid etching apparatus – With mechanical mask – shield or shutter for shielding workpiece
Reexamination Certificate
2001-09-24
2004-05-18
Hassanzadeh, Parviz (Department: 1763)
Adhesive bonding and miscellaneous chemical manufacture
Differential fluid etching apparatus
With mechanical mask, shield or shutter for shielding workpiece
C156S345100, C355S053000
Reexamination Certificate
active
06736928
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to an exposure apparatus used to form microcircuit patterns in manufacturing devices such as semiconductor chips and a method of manufacturing semiconductor devices using the exposure apparatus.
BACKGROUND OF THE INVENTION
As a conventional technology, there are two systems mainly used by an exposure apparatus for applying exposure to a mask pattern (device pattern); a step and repeat system that performs exposure (printing) of mask patterns on a photo-mask through collective illumination and a scan and repeat system that applies split illumination to a mask pattern through slits and completes a predetermined mask pattern while scanning the photo-mask and the wafer in synchronization with each other.
Furthermore, an exposure system called “flash on the fly” was proposed in the past. This is a system that completes a latent image on a wafer on a wafer stage running at a constant velocity through one-time exposure using pulse light with an extremely short life such as excimer laser light, and the this system is described in U.S. Pat. No. 4,095,891 and Japanese Patent Laid-Open No. 62-176129, etc.
However, the step and repeat system moves and stops the wafer stage repeatedly for every one shot area and must perform exposure after stopping and setting the shot area at a predetermined pattern projection position, while the scan and repeat system needs a cycle of accelerating the wafer stage for every one shot, performing exposure when the stage reaches a constant velocity area and decelerating the stage after exposure. Thus, it is necessary to control the complicated movement of the stage required for exposure in synchronization with optical elements, which causes throughput to decrease.
On the other hand, the flash on the fly system moves the wafer stage at a constant velocity, but since exposure onto one shot area of a wafer is performed with one-time emission of pulse light with an extremely short life, the exposure energy of the pulse light must be stabilized exactly. With such energy control, it is quite difficult to achieve desired accuracy even if the discharge voltage, gas pressure or gas circulation velocity, etc., are controlled.
SUMMARY OF THE INVENTION
The present invention has been proposed to solve the conventional problems, and has as its object to provide an exposure apparatus and a method of manufacturing semiconductor devices using the exposure apparatus characterized by having the following configuration. That is, the present invention provides an exposure apparatus that performs exposure of device patterns provided in the pattern effective area of a photo-mask sequentially onto shots of a wafer, the apparatus comprising:
an illumination unit that collectively illuminates the entire pattern effective area of the photomask contained in the illumination range with exposure light;
a mask stage that moves the photo-mask in the mask scanning direction for the illumination range;
a wafer stage that moves the wafer in the wafer scanning direction within the projection range in which the pattern effective area of the photo-mask is projected; and
control means for containing at least one of the shot areas within the projection range to perform exposure of the device patterns provided in the pattern effective area of the photo-mask onto the shot area of the wafer and controlling and synchronizing the movements of the mask stage and the wafer stage while keeping the entire pattern effective area of the photo-mask contained within the illumination range.
The wafer stage of the above-described exposure apparatus preferably moves at a constant velocity or a substantially constant velocity so that a plurality of shot areas of the wafer is contained sequentially within the projection range.
The illumination unit of the above-described exposure apparatus preferably comprises a laser light source that emits pulse light,
wherein the laser light source emits pulse exposure light at least one to perform exposure of the device patterns provided in the pattern effective area of the photo-mask onto one of shot areas of the wafer.
The above-described exposure apparatus preferably comprises a projection lens for projecting the pattern effective area of the photo-mask within the projection range,
wherein the control means keeps the entire pattern effective area of the photo-mask contained within the field of view range of the projection lens while synchronizing and controlling the movements of the mask stage and the wafer stage.
The above-described exposure apparatus preferably satisfies the relationship:
D≧
((
Ma+Mb
)
2
+Md
2
)
1/2
where,
Ma: Length of pattern effective area of the photo-mask in the mask scanning direction;
Mb: Amount of movement of the photo-mask in the mask scanning direction when exposure is performed onto one of shot areas of the wafer:
Md: Width of the photo-mask; and
D: Diameter of the field of view range.
The above-described exposure apparatus preferably satisfies the relationship:
Ta≦
(
Wa−Wb
)/V
where,
Ta: Time after exposure of one shot area of the wafer is completed, then the mask stage is returned to the initial position in the mask scanning direction until synchronization is established with the wafer stage that has moved in the wafer scanning direction for an exposure of the next shot area of the wafer;
V: Moving velocity of the wafer stage;
Wa: Length of one shot area of the wafer in the wafer scanning direction; and
Wb: Amount of movement of the wafer in the wafer scanning direction when exposure is performed onto one shot area of the wafer.
The mask stage of the above-described exposure apparatus is preferably returned to an initial position for every one row or one column of consecutive shot areas of the wafer, and
the time for returning to the initial position is made shorter than the time of movement for changing the row or column of the wafer stage in order to move to the next shot area.
The illumination unit of the above-described exposure apparatus preferably comprises an illumination sensor to determine whether a predetermined amount of exposure has been reached or not, and
terminates pulse emission of the laser light source when the total amount of exposure of the illumination sensor has reached a predetermined amount of exposure.
The above-described exposure apparatus preferably comprises voltage measuring means for measuring an applied voltage of the laser light source, gas concentration measuring means for measuring gas concentration in a chamber of the laser light source and storing means for storing light emission history of the laser light source as data,
wherein the laser light source calculates total exposure energy based on any one of or a combination of measurement results of the voltage measuring means and gas concentration measuring means or the light emission history data and controls from the calculation result so that the next pulse light emission reaches a predetermined level of exposure energy.
The illumination unit of the above-described exposure apparatus preferably comprises a micro mirror array for adjusting exposure energy in the light path,
wherein the micro mirror array is controlled based on information of any one or a combination of the illumination sensor, the voltage control means, the gas concentration measuring means the light emission history data so that pulse light emission reaches a predetermined level of exposure energy.
The above-described exposure apparatus preferably controls the pulse light emission count for one shot area of the wafer under the relationship of I·S/(J·P),
where,
I: Amount of required exposure per unit area;
S: Area of one shot area of the wafer;
J: Energy of one-time pulse light emission from the laser light source; and
P: Transmittance for light with exposure wavelength from the laser light source to the wafer.
Furthermore, the semiconductor device manufacturing method according to the present invention comprises the steps of:
installing a plurality of semiconductor manufacturing apparatuses, including the exposure a
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