Nozzle reposition device used in a resist coating process

1. Field of the Invention

The present invention provides a resist spray nozzle resetting device, namely a device for achieving uniformity of resist coating on a semiconductor wafer.

2. Description of the Prior Art

In semiconductor manufacturing processes, a semiconductor wafer must go through many coating processes from start to finish, such as lithographic resist and developer coating processes. With the narrowing line width in semiconductor processes, photolithographic technology has become critical, for it is with photolithography that all the MOS components, metallic wires, thin film patterns and dopant regions are made. Moreover, the pattern-transferring process, mandatory in photolithography, is complicated and subtle, and so only a precise pattern of resist can ensure the reliability of later processes.

In today's market, most resist coating processes are performed by spin-coating liquid resist over a wafer to form a resist layer with an even thickness. This forms a light-sensitive photo-emulsion layer. Since the uniformity of the thickness of a resist layer can later affect the resolution, the depth of focus (DOF), and even the quality of the wafer, it is important in wafer production to know how to achieve and maintain the uniformity of the resist layer.

Please refer to FIG. 1 . FIG. 1 is a front view of a resist coating device 10 according to the prior art. As shown here, the resist coating device 10 comprises a rotary robotic arm 12 and a spray nozzle 14 . The spray nozzle 14 has a covering nut 16 fastened on the rotary arm 12 . The spray nozzle 14 sprays resist 18 over a wafer's surface 20 which, positioned on a vacuum rotary station 22 , is kept in rotating motion. Ideally, the spray nozzle aims straight at the midpoint 26 of the wafer 20 ; in other words, it forms a line with the central axis 24 , so that the resist 18 drops directly on the midpoint 26 of the wafer 20 and coats the wafer surface. Unfortunately, sometimes the spray nozzle 14 might move astray from the center axis 24 due to maintenance errors or operating negligence, causing the resist 18 to fall off the midpoint 26 , resulting in a non-uniform resist coating. Even though resetting of the spray nozzle 14 can be done manually, if it is off of the central axis 24 , it wastes both time and money, and alignment errors after manual resetting are not negligible.

The purpose of the present invention is to provide a spray nozzle resetting device to correct the weaknesses of the conventional counterpart described above.

Another purpose of the present invention is to provide a spray nozzle resetting device to avoid misalignment problems, so as to improve the uniformity of the resist layer.

In a preferred embodiment of the present invention, a spray nozzle resetting device comprises a spray nozzle for spraying resist on the midpoint of a wafer, a rotary robotic arm, a resist-delivering duct connected to one end of the spray nozzle, a covering nut, a resetting ring, a fixing ring connecting the covering nut to the rotary robotic arm, and a spring positioned between the covering nut and the resetting ring. The covering nut has an opening of diameter D. The resetting ring has a rotary part with a diameter equal to or less than D, and at last two protrusions. The rotary part fits in the opening of the covering nut. The fixing ring is used to fix the covering nut to the rotary robotic arm, and it has two recesses corresponding to the two protrusions to interact with the two protrusions.

In the preferred embodiment, the midpoint of the resetting ring is not aligned with the two protrusions. To move the spray nozzle, the operator can lift up the rotary part of the fixing ring and rotate it to a desired angle, with the spray nozzle rotating along with it. For performing the resist coating process, the operator can rotate the rotary part in the reverse direction until the two protrusions re-catch on the two recesses, so as to again aim the spray nozzle at the midpoint of the wafer.

FIG. 1 is a front view of a resist spray nozzle according to the prior art.

FIG. 2 is an exploded diagram of a spray nozzle resetting device according to the present invention.

FIG. 3A is a side view of a resetting ring of the present invention.

FIG. 3B is a front view of a resetting ring of the present invention.

FIG. 3C is a rear view of a resetting ring of the present invention.

FIG. 4A is a cross-sectional view of a fixing ring of the present invention.

FIG. 4B is a front view of a fixing ring of the present invention.

FIG. 5 is a perspective view of a spray nozzle resetting device according to the present invention.

Please refer to FIG. 2 . FIG. 2 is an exploded diagram of a spray nozzle resetting device 30 according to the present invention. As shown here, the spray nozzle resetting device 30 comprises a spray nozzle 34 bent at a 90 degree angle that is used to spray resist on the midpoint of a wafer, a rotary robotic arm 32 for resist delivery, a covering nut 36 with an opening 36 a of diameter D, a spring 44 , a resetting ring 38 and a fixing ring 42 for connecting the covering nut 36 to the rotary robotic arm 32 . The spring 44 is located between the covering nut 36 and the resetting ring 38 , and is fixed resiliently on the rotary part 38 a , providing a tightening force between the resetting ring 38 and the fixing ring 42 . The rotary robotic arm 32 has a resist-delivering duct 32 a connected to one end of the spray nozzle 34 .

In the preferred embodiment, the spray nozzle 34 is made of stainless steel, and is bent at 90 degrees. Additionally, the spraying end of the spray nozzle 34 is equipped with a plastic head 34 a . The spray nozzle 34 of the present invention, however, is not restricted to this particular material and bending angle. Other materials and bending angles can be used for the spray nozzle 34 .

Please refer to FIG. 3A, which is an enlarged side view of the resetting ring 38 according to the present invention. The resetting ring 38 comprises a rotary part 38 a on one side, and at least two protrusions 38 b on the opposite side. The rotary part 38 a fits into the opening 36 a of the covering nut 36 . Additionally, the rotary part 38 a has at least one screw hole 38 c that accommodates a bolt to secure the spray nozzle 34 . The resetting ring 38 has in its center a hole 38 d to accommodate the spray nozzle 34 . The hole 38 d extends through the resetting ring 38 , including the rotary part 38 a . There are in the rotary part 38 a two screw holes 38 c going through the hole 38 d for securing the spray nozzle 34 with a screw bolt, making the spray nozzle 34 and the rotary part 38 a rotate together.

Please refer to FIG. 3B, which is a front view of the resetting ring 38 according to the present invention. The rotary part 38 a is located on one side of the resetting ring 38 , and the two protrusions 38 b are on the opposite side. The diameter of the rotary part 38 is equal to or less than D, so that it may pass through the opening 36 a of the covering nut 36 .

“Please refer to FIG. 3C, which is a rear view of the resetting ring 38 according to the present invention The two protrusions 38 b and 38 e have distances of d 1 and d 2 from the center of the circle, respectively. In the preferred embodiment, d 1 is not equal to d 2 , and d 1 and d 2 are less than the diameter 39 of the resetting ring 38 . Additionally, the two protrusions 38 b and 38 e are not aligned together with the center point of the circle.”

“Please refer to FIG. 4 A and FIG. 4 B. FIG. 4 A and FIG. 4B are, respectively, a cross-sectional side view and a front view of the fixing ring 42 according to the present invention. As shown in FIG. 4A, the fixing ring 42 comprises a front part 45 and a rear part 46 . The front part 45 is screwed tightly to the covering nut 36 , and the rear part 46 to the rotary robotic arm 32 . In other words, the main function of the fixing ring 42 is to join together the covering nut 36 and the rotary robotic arm 32 . Moreover, the fixing ring 42 has in its center an opening 42 a that accommodates the spray nozzle 34 and the resist-delivering duct 32 a . There are two screw holes 42 b in the rear part 46 for securing the resist-delivering duct 32 a , which runs across the rear part.”

The fixing ring 42 has an the inner side 47 of the rear part 45 two recesses 42 c , which correspond to and interact with the two protrusions 38 b of the resetting ring 38 . In the preferred embodiment, the center point of the fixing ring 42 is not aligned with the two recesses 42 c . As shown in FIG. 3 C and FIG. 4B, the diameter 43 of the inner circle of the front part 45 of the fixing ring 42 is slightly longer than the diameter 39 (in FIG. 3C) of the resetting ring 38 .

What is worth noticing is that because the distances d 1 and d 2 from the two protrusions 38 b and 38 c to the center point of the circle, respectively, are not the same, and because the two protrusions 38 b and 38 c , and the center point of the resetting ring 38 are not aligned, the spray nozzle can have only one reset position.

Please refer to FIG. 5, which is a perspective view of the spray nozzle resetting device 30 according to the present invention. As shown here, to move the spray nozzle 34 for regular maintenance, the operator first pulls out the rotary part 38 a in the direction of the arrow 51 , and rotates it clockwise or counter clockwise through an angle. Since the spray nozzle 34 has been screwed securely to the rotary part 38 a , the spray nozzle 34 moves together through the same angle as the rotary part 38 a . When the operator releases the rotary part 38 a , the resetting ring 38 and the fixing ring 42 are kept in contact by the force provided by he spring 44 , allowing the spray nozzle 34 and the resetting device 30 to remain in the maintenance position. After the maintenance procedure has been completed, and when the operator needs to run another resist coating process, he or she may rotate the rotary part 38 a in the reverse direction until the two protrusions 38 b re-catch the two recesses 42 c , ensuring that the spray nozzle 34 points at the midpoint 86 of the wafer 80 , and aligning it with the center axis.

It should be remembered that before using the spray nozzle resetting device 30 , the operator should correct the spray nozzle 34 by aiming it at the midpoint 86 of the wafer 80 and aligning it with the center axis 84 . It is only after the correction that the operator may secure with screw bolts the spray nozzle 34 to the rotary part 38 a of the resetting ring 38 . In this manner, the operator ensures that the spray nozzle points precisely at the midpoint 86 of the wafer 80 for each run.

In comparison to the prior art, the present invention is superior in that it solves the resetting problem of the spray nozzle 34 , which the operator often encounters after a maintenance procedure. Because of this invention, the spray nozzle 34 can now be accurately aimed at the midpoint 86 of the wafer 80 in resist coating processes, thus improving the uniformity of resist and the reliability of the later photolithographic processes.

The above disclosure is based on the preferred embodiment of the present invention. Those skilled in the art will readily observe that numerous modifications and alterations of the device may be made while retaining the teachings of the invention. Accordingly, the above disclosure should be construed as limited only by the metes and bounds of the appended claims.