TWI799140B - Single wafer cleaning apparatus and monitor method thereof - Google Patents

Abstract

A single wafer cleaning apparatus includes a platform, a wafer holder for securing a wafer, and a distance sensor. The wafer holder is configured to secure the wafer and rotates relative to the platform. The distance sensor is disposed over the wafer holder to detect a distance between the distance sensor and an edge of the wafer holder. A monitor method of the single wafer cleaning apparatus is also disclosed.

Description

Single wafer cleaning equipment and its monitoring method

The invention relates to a wafer cleaning device and a monitoring method thereof.

In semiconductor manufacturing, after a processing step, reaction residues are usually left on the wafer. For example, after the etching step, substances such as high molecular polymers are often left on the wafer. In order to prevent these process residues from affecting the subsequent process, and to prevent the reaction chamber and other wafers from being polluted by process residues, most of the current wafers are cleaned after a processing step, so as to remove the adhesion on the wafer. Process residues on the wafer to ensure process reliability.

Wet etching and wet cleaning of wafers is usually accomplished by immersing the batch of wafers in a liquid, and sometimes by spraying the liquid on the batch of wafers. However, a standard cleaning cycle for a lot of wafers takes a long time to complete, thus requiring a fast single wafer cleaning process.

One embodiment of the present invention relates to a single wafer cleaning equipment, including a platform, a wafer support for holding the wafer, and a distance sensor. The wafer support rotates the wafer relative to the stage. The distance sensor is disposed on the wafer support for measuring the distance between the distance sensor and the outer edge of the wafer support.

In some embodiments, the single-wafer cleaning equipment further includes a processing unit, and the processing unit is connected to a distance sensor to issue an alarm signal after determining that the wafer support member is operating abnormally.

In some embodiments, the distance sensor includes a laser source and a receiver, and the emitting direction of the laser source and the receiving direction of the receiver are substantially perpendicular to the wafer support.

In some embodiments, the wafer support includes gripper fingers for holding the wafer, and the distance sensor is positioned to align with the gripper fingers.

In some embodiments, the single wafer cleaning apparatus further includes a liquid nozzle for spraying a cleaning solution on the wafer.

In some embodiments, the single wafer cleaning apparatus further includes a gas nozzle for providing gas through the upper surface of the wafer.

Another embodiment of the present invention relates to a monitoring method for single wafer cleaning equipment, including detecting the distance between the wafer support and the distance sensor; judging whether the change in the distance is greater than a preset value; judging the Whether the duration of the change in distance greater than the preset value is greater than the preset time; and when the change in the distance between the wafer support and the distance sensor is greater than the preset value, and the change in the distance is greater than the preset When the duration of the value is also greater than the preset time, a warning signal is issued.

In some embodiments, the step of detecting the distance between the wafer support and the distance sensor is performed while the wafer support is holding the wafer in rotation.

In some embodiments, the step of detecting the distance between the wafer support and the distance sensor includes detecting the distance between the gripping fingers of the wafer support and the distance sensor.

In some embodiments, the monitoring method of the single wafer cleaning equipment further includes shutting down for maintenance after an alarm signal is issued.

The above-mentioned single-wafer cleaning equipment and its monitoring method can monitor the operating status of the wafer support in real time during the single-wafer cleaning process, and send a warning signal when the wafer support operates abnormally, so as to perform The abnormal operation of the wafer support is eliminated before the cleaning process of the next wafer, thereby improving the manufacturing yield of the wafer.

The following will clearly illustrate the spirit of the present invention with drawings and detailed descriptions. Anyone with ordinary knowledge in the technical field can change and modify it by the technology taught in the present invention after understanding the preferred embodiments of the present invention. It does not depart from the spirit and scope of the present invention.

In the single wafer cleaning process, the removal of polymers on the wafer can be performed on a rotary machine. The rotary machine can provide an automated single-wafer chemical cleaning process, which is suitable for the processing of the front, back and edge of the wafer. When using a rotary machine to clean the polymer on the wafer, the cleaning solution is applied to the wafer from above the wafer while the wafer is rotating. The centrifugal force generated by the rotation makes the cleaning solution cover the entire wafer to make the cleaning solution react with the residue, and then the cleaning reactants are removed from the wafer surface by centrifugal force. Then, the wafer is dried by blowing the dry gas to complete a cycle of wafer cleaning. If the cleanliness of the wafer still does not meet the process standard at this time, the wafer can be cleaned repeatedly according to the above steps until the cleanliness of the wafer has reached the process standard.

Referring to FIG. 1 , it is a schematic side view of an embodiment of a single wafer cleaning equipment of the present invention. The single wafer cleaning apparatus 100 includes a platform 110 , a wafer support 120 , at least one nozzle 130 , and a distance sensor 140 . The wafer 200 is held on the wafer support 120, and the wafer support 120 can rotate the wafer 200 about its central axis at a predetermined rate relative to the stage 110.

In some embodiments, wafer support 120 may be designed to hold wafer 200 in a desired orientation on a balanced underlying fluid according to Bernoulli's law. Alternatively, in other embodiments, the wafer support 120 may cooperate with gripping fingers 122 engaging the peripheral edge of the wafer 200 to mechanically hold the wafer 200 . The size of the gripping fingers 122 is designed to correspond to the diameter of the wafer, wherein 300 mm is the most common wafer diameter currently used.

In some embodiments, the platform 110 includes a plurality of sonic converters 112. The sonic converters 112 are preferably capable of generating megasonic with a frequency range above 350 kHz, and the specific frequency depends on the wafer 200. Depending on thickness. The sound wave transducer 112 may be a piezoelectric device capable of generating sound waves or sound waves in a direction perpendicular to the surface of the wafer 200 to remove particles on the surface of the wafer 200 .

In some embodiments, deionized water (de-ion water; DIW) is provided through the channel 114 and fills the gap between the back of the wafer 200 and the platform 110 , so that the sound wave generated by the sound wave converter 112 can be transmitted to the wafer 200 . Preferably, the deionized water filled between the wafers 200 and the wafers 200 has been degassed, so that the sound waves are stronger and thereby reduce the possibility of damaging the wafers 200 .

Nozzles 130 include liquid nozzles 132 for supplying cleaning chemicals or rinse water (such as deionized water) to the upper surface of wafer 200 so that when wafer support 120 holds wafer 200 and rotates , a liquid coating may be formed on the upper surface of the wafer 200 .

For example, a cleaning procedure may include stages such as HF-SC1-SC2. Hydrofluoric acid (HF) is a solution used to etch a thin oxide layer, followed by a standard clean 1 solution (SC1 solution) consisting of a mixture of NH ₄ OH, H ₂ O ₂ and H ₂ O ). SC1 solution is mainly used to remove particulates and residual organic contamination. Finally a standard clean 2 solution (SC2 solution) containing a mixture of HCl, _H2O2 and _H2O . SC2 solution is mainly used to remove metal contamination. The deionized water rinse (rinse) step will be placed between the HF, SC1 and SC2 solutions, usually after the SC2 solution will be rinsed with deionized water again and the wafer will be dried.

In some embodiments, the liquid nozzle 132 may spray the cleaning solution at a fixed point (eg, at the center of the wafer 200 ). Alternatively, in some other embodiments, the liquid nozzle 132 may spray the cleaning solution back and forth on the wafer 200 in a scanning manner. The liquid nozzle 132 is further connected to each solution/deionized water supply source through pipelines.

In addition, the nozzle 130 may further include a gas nozzle 134, which is used to pass nitrogen and/or isopropanol gas through the upper surface of the wafer 200 during the rinsing and/or drying steps to quickly remove moisture. And the surface of the wafer 200 is dried. In addition, the distance between the wafer 200 held by the wafer support 120 and the platform 110 is increased, for example by moving the wafer support 120 or the platform 110, so that the backside of the wafer 200 is no longer subjected to liquid-filled pressure. The constraint of the gap thereby allows the wafer 200 to be rotated at a very high speed during drying operations, for example.

Since the stability of the wafer support 120 during rotation will affect the uniformity of the distribution of the cleaning solution, and even cause defects on the wafer 200, therefore in order to ensure the stability of the wafer support 120 during operation, a single The wafer cleaning equipment 100 uses the distance sensor 140 to observe the operation status of the wafer support 120 in real time.

Please refer to FIG. 1 and FIG. 2 at the same time, wherein FIG. 2 is a schematic top view of an embodiment of the single wafer cleaning equipment 100 in operation of the present invention. When a single wafer cleaning process is performed, the grasping fingers 122 of the wafer support 120 clamp the periphery of the wafer 200 so that the wafer 200 is held on the wafer support 120 . The distance sensor 140 is disposed in the front direction of the wafer support 120 to sense the distance between the distance sensor 140 and the wafer support 120 from the vertical direction of the wafer 200 .

More specifically, since the wafer support 120 tends to vibrate the most at the outermost edge of the wafer support 120 when it does not operate normally, the distance sensor 140 is preferably set to Align the outermost edge of the wafer support 120 , such as aligning the grasping fingers 122 of the wafer support 120 , to improve the accuracy of interpretation.

In some embodiments, the distance sensor 140 can be a laser sensor, and the distance sensor 140 can include a laser source 142 that emits a laser beam L1 on the wafer 200, and the position of the reflected beam L2 is obtained by receiving Detected by the detector 144, wherein the angle between the laser source 142 and the receiver 144 is extremely small, the emission direction of the laser source 142 and the receiving direction of the receiver 144 are substantially perpendicular to the wafer support 120, and the laser beam L1 and reflected light beam L2 can be almost regarded as parallel light.

The distance sensor 140 is further connected to a processing unit 150 . When the wafer 200 is rotating, the distance sensor 140 can emit a laser beam L1 at a fixed point on the outer edge of the wafer support 120, such as on the gripping finger 122, to measure the distance between the wafer support 120 and the distance sense in real time. The distance between the detectors 140 is sent back to the processing unit 150, so as to monitor whether the wafer support 120 maintains stable operation when the wafer 200 rotates, and after the processing unit 150 judges that the wafer support 120 is operating abnormally, A warning signal is issued to alert operators that the wafer support 120 requires maintenance.

As shown in FIG. 3A and FIG. 3B , they are the distance-time charts of the stable operation and abnormal operation of the wafer support in an embodiment of the single wafer cleaning equipment of the present invention. If the wafer support is operating smoothly, then as shown in Figure 3A, the distance between the wafer support and the distance sensor will roughly maintain a constant value, and if the wafer support is operating abnormally, as shown in Figure 3B As shown in the figure, the distance between the wafer support and the distance sensor has a relatively obvious amplitude, and this amplitude has certain regularity. Therefore, when the amplitude of the distance between the wafer support and the distance sensor is greater than a preset value, such as greater than plus or minus 0.2 cm, and lasts for a period of time, such as more than five seconds, it means that the wafer support is abnormal and needs to be adjusted. Shutdown for maintenance.

Referring to FIG. 4 , it is a flow chart of an embodiment of the monitoring method of the single wafer cleaning equipment of the present invention. First, step 402 is to detect the distance between the wafer support and the distance sensor, wherein the distance sensor can be a combination of a laser source and a receiver, and the distance sensor is on the vertical side of the wafer support. direction to detect the distance between the wafer support and the distance sensor. Step 402 is performed while the wafer is held on the wafer support and performing single wafer cleaning.

Next, step 404 is to judge whether the amount of change (i.e. amplitude) of the distance is greater than a preset value, if the amount of change of the distance is greater than the preset value, such as greater than plus or minus 0.2 centimeters, then proceed to step 406 to judge the amount of change of the distance Whether the duration greater than the preset value is greater than the preset time, such as greater than five seconds. Since the aforementioned step 402 is performed while the wafer is held on the wafer support and performing single-wafer cleaning, sometimes in practice, the fluid on the surface of the wafer support or the grabbing of the wafer support The surface topography of the finger causes the distance to change slightly. In order to eliminate these changes, the judgment values in step 404 and step 406 of the embodiment of the present invention are arranged.

If in step 404 and step 406, the variation of the distance between the wafer support and the distance sensor is greater than the preset value, and the duration of the variation of the distance greater than the preset value is also greater than the preset time, it means Wafer support malfunctioning. Then enter step 408, send a warning signal to remind personnel, then enter step 410, carry out shutdown maintenance.

The shutdown maintenance action in step 410 can be set to wait for the current wafer cleaning process to be completed, or to directly shut down while an alarm is issued. Regardless of the situation above, the abnormal operation of the wafer support can be ruled out before performing the cleaning process on the next wafer, thereby improving the manufacturing yield of the wafer.

The single-wafer cleaning equipment and its monitoring method provided in one embodiment of the present invention can monitor the operating status of the wafer support in real time during the single-wafer cleaning process, and detect abnormal operation of the wafer support When a warning signal is issued, the abnormal operation of the wafer support is eliminated before the next wafer is cleaned, thereby improving the wafer manufacturing yield.

Although the present invention has been disclosed as above with the embodiments, it is not intended to limit the present invention. Anyone skilled in this art can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the protection of the present invention The scope shall be defined by the appended patent application scope.

100:Single wafer clean equipment 110: Platform 112:Sonic Converter 114: channel 120: Wafer support 122: grab finger 130: Nozzle 132: liquid nozzle 134: gas nozzle 140: distance sensor 142: Laser source 144: Receiver 150: processing unit 200: Wafer L1: laser beam L2: reflected beam 402: step 404: step 406: step 408: Step 410: Step

In order to make the purpose, features, advantages and embodiments of the present invention more obvious and understandable, the detailed description of the accompanying drawings is as follows: FIG. 1 is a schematic side view of an embodiment of a single wafer cleaning equipment of the present invention. Fig. 2 is a schematic top view of an embodiment of the single wafer cleaning equipment of the present invention in operation. FIG. 3A and FIG. 3B are the distance-time graphs of the stable operation and abnormal operation of the wafer support in an embodiment of the single wafer cleaning equipment of the present invention, respectively. FIG. 4 is a flow chart of an embodiment of the monitoring method of the single wafer cleaning equipment of the present invention.

Domestic deposit information (please note in order of depositor, date, and number) none Overseas storage information (please note in order of storage country, institution, date, and number) none

100:Single wafer clean equipment

110: Platform

112:Sonic Converter

114: channel

120: Wafer support

122: grab finger

130: Nozzle

132: liquid nozzle

134: gas nozzle

140: distance sensor

142: Laser source

144: Receiver

150: processing unit

200: Wafer

L1: laser beam

L2: reflected beam

Claims (9)

A single wafer cleaning equipment, comprising: a platform; a wafer support, used to hold a wafer, so that the wafer rotates relative to the platform; a distance sensor, arranged on the wafer support, for measuring a distance between the distance sensor and an outer edge of the wafer support; and a processing unit connected to the distance sensor for judging whether a change in the distance is greater than a predetermined Setting a value; judging whether the variation of the distance is greater than the preset value for a duration greater than a preset time; and when the variation of the distance between the wafer support and the distance sensor is greater than the When the change amount of the distance is greater than the preset value and the duration is greater than the preset time, a warning signal is sent. The single wafer cleaning equipment as claimed in item 1, wherein the distance sensor includes a laser source and a receiver, the emitting direction of the laser source and the receiving direction of the receiver are substantially perpendicular to the wafer supporting item. The single wafer cleaning equipment as claimed in claim 1, wherein the wafer support includes a gripping finger for clamping the wafer, and the distance sensor is arranged to align with the gripping finger. The single wafer cleaning device as claimed in claim 1 further comprises a liquid nozzle for spraying a cleaning solution on the wafer. The single wafer cleaning equipment as claimed in Claim 1 further comprises a gas nozzle for providing a gas through the upper surface of the wafer. A monitoring method for single wafer cleaning equipment, comprising the following steps: detecting a distance between a wafer support and a distance sensor; judging whether a variation of the distance is greater than a preset value; judging the distance whether the duration of the variation is greater than the preset value is greater than a preset time; and when the variation of the distance between the wafer support and the distance sensor is greater than the preset value, and the When the change amount of the distance is greater than the preset value and the duration is also greater than the preset time, a warning signal is sent. The monitoring method of single wafer cleaning equipment as described in claim 6, wherein the step of detecting the distance between the wafer support and the distance sensor is to hold a wafer rotating on the wafer support simultaneously. The monitoring method of single wafer cleaning equipment as described in claim 6, wherein the step of detecting the distance between the wafer support and the distance sensor comprises detecting a grasping index of the wafer support A vertical distance from the distance sensor. The monitoring party of the single-wafer cleaning equipment as described in claim 6 method, further comprising performing a shutdown for maintenance after the warning signal is issued.

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