Patent Application
20230256480
The present invention generally relates to semiconductor wafer cleaning, and more particularly, to wet cleaning methods and apparatus employing controlled sonic energy.
Semiconductor devices are manufactured or fabricated on semiconductor wafers employing a sequence of processing steps to create transistors and interconnection elements. These transistors are traditionally built in two dimensions but more recently in three dimensions, such as finFET transistors, as well. The interconnection elements include conductive (e.g., metal) trenches, vias, and the like formed in dielectric materials.
In forming these transistors and interconnection elements, semiconductor wafers undergo multiple masking, etching, and deposition processes to form desired structures for the semiconductor devices. For example, multiple masking and plasma etching steps are performed to form recessed areas in a dielectric layer on a semiconductor wafer that serve as fins for a finFET transistor and trenches and vias for the interconnection elements. In order to remove particles and contaminations in fin structures and/or trench and via post etching or photoresist ashing, a wet cleaning step is necessary. However, a wet cleaning with chemicals may result in side wall loss. When device manufacture node migrates down to 14 or 16 nm and beyond, reducing side wall loss in fins, trenches and vias becomes crucial for maintaining critical dimensions. In order to reduce or eliminate the side wall loss, it is important to use moderate or diluted chemicals and sometimes even de-ionized water only. However, the moderate or diluted chemicals or de-ionized water are usually not efficient enough to remove particles in the fin structures and/or trenches and vias. As a result, mechanical force generated by ultra or mega sonic energy, for instance, is needed in order to remove those particles efficiently. Ultra sonic or mega sonic waves generate bubble cavitation to apply mechanical force to the wafer structures under cleaning.
However, cavitation is a chaotic phenomenon. Onset of cavitation bubble and its collapse is affected by many physical parameters. A violent cavitation such as transit cavitation or micro jet can damage those patterned structures (fins, trenches and vias). In a conventional ultra sonic or mega sonic cleaning process, significant particle removal efficiency (“PRE”) occurs only when the power is high enough, for example greater than 5-10 watts. However, significant wafer damages begin to occur when the power is greater than about 2 watts. Therefore, it is difficult to find a power window where the wafer can be cleaned efficiently without causing significant damages. Therefore, maintaining a stable or controlled cavitation is a key for controlling the sonic mechanical force to be below a damage limit while still being capable of efficiently removing foreign particles from the patterned structures.
As such, it is desirable to provide a system and method for controlling bubble cavitation generated by ultra or mega sonic devices during a wafer cleaning process to be able to efficiently remove fine foreign particles without damaging patterned structures on the wafer.
A system for cleaning semiconductor wafers is disclosed which includes a wafer holder for temporary restraining a semiconductor wafer during a cleaning process, an inlet for delivering a cleaning liquid over a surface of the semiconductor wafer, a sonic generator configured to alternately operate at a first predetermined setting for a first predetermined period of time and at a second predetermined setting for a second predetermined period of time, and a controller programmed to determine the first and the second predetermined setting, the first and the second period of time and a number of the alternations between the first and second predetermined settings by the sonic generator, wherein bubble cavitation in the cleaning liquid increases during the first predetermined period of time and decreases during the second predetermined period of time. The first predetermined period of time and the second predetermined period of time consecutively follow one another. Therefore, the bubbles in the cleaning liquid can be sufficiently cooled down after the cleaning in each first period of time to avoid damages to the wafer.
Other aspects, features, and techniques will be apparent to one skilled in the relevant art in view of the following detailed description of the embodiments.
The drawings accompanying and forming part of this specification are included to depict certain aspects of the present disclosure. A clearer conception of the present disclosure, and of the components and operation of systems provided with the present disclosure, will become more readily apparent by referring to the exemplary, and therefore non-limiting, embodiments illustrated in the drawings, wherein like reference numbers (if they occur in more than one view) designate the same elements. The present disclosure may be better understood by reference to one or more of these drawings in combination with the description presented herein. It should be noted that the features illustrated in the drawings are not necessarily drawn to scale.
One aspect of the disclosure relates to controlling bubble cavitation in semiconductor wafer cleaning with sonic energy. Embodiments of the present disclosure will be described hereinafter with reference to the attached drawings.
Referring again to
Referring to
p
0
v
0
/T
0
=pv/T (1)
where p0 is a pressure inside the bubble before compression, v0 is an initial volume of the bubble 5016 before compression, T0 is a temperature of gas inside the bubble before compression, p is a pressure inside the bubble during compression, v is a volume of the bubble during compression, and T is a temperature of gas inside the bubble during compression.
In order to simplify the calculation, we may assume the temperature of gas does not change during the compression or the compression is very slow and temperature increase is cancelled by liquid surrounding the bubble. So the mechanical work wm caused by sonic pressure PM during one time of bubble compression (from volume N unit to volume 1 unit, or compression ratio=N) can be expressed as follows:
where S is an area of cross section of a cylinder, x0 is a length of the cylinder, p0 is a pressure of gas inside the cylinder before the compression. Equation (2) does not consider the factor of temperature increase during the compression, so that the actual pressure inside the bubble will be higher due to temperature increase. Therefore the actual mechanical work by sonic pressure will be larger than the value calculated by equation (2).
Assuming the mechanical work by sonic pressure is partially converted to thermal energy and partially converted mechanical energy of high pressure gas and/or vapor inside the bubble, and such thermal energy is fully contributed to temperature increase of gas inside the bubble (no energy is transferred to liquid molecules surrounding the bubble), and assuming the mass of gas inside the bubble stays constant before and after the compression, a temperature increase ΔT after one time of compression of bubble can be expressed by the following formula:
ΔT=Q/(mc)=βwm/(mc)=βSx0p0ln(x0)/(mc) (3)
where Q is thermal energy converted from mechanical work, β is a ratio of thermal energy to total mechanical work by sonic pressure, m is a mass of gas inside the bubble, c is a specific heat coefficient of the gas. If β=0.65, S=1E-12 m2, x0=1000 μm=1E-3 m (compression ratio N=1000), p0=1 kg/cm2=1E4 kg/m2, m=8.9E-17 kg for hydrogen gas, c=9.9E3 J/(kg °k), then ΔT=50.9° C.
The temperature T1 of gas inside the bubble after the first compression can be calculated as:
T
1
=T
0
+ΔT=20° C.+50.9° C.=70.9° C. (4)
when the bubble reaches the minimum size of 1 micron as shown in
T
2
=T
1
−δT=T
0
+ΔT−δT (5)
where δT is a temperature decrease after one time of expansion of the bubble, and δT is smaller than ΔT.
When a second cycle of bubble cavitation reaches the minimum bubble size, the temperature T3 of gas and/or vapor inside the bubble will be:
T
3
=T
2
±ΔT=T
0
+ΔT−δT+ΔT=T
0+2ΔT−δT (6)
When the second cycle of bubble cavitation finishes, the temperature T4 of gas and/or vapor inside the bubble will be:
T
4
=T
3
−δT=T
0+2ΔT−δT−δT=T0+2ΔT−2δT (7)
Similarly, when the nth cycle of bubble cavitation reaches the minimum bubble size, the temperature T2n-1 of gas and/or vapor inside the bubble will be:
T
2n-1
=T
0
+nΔT−(n−1)δT (8)
When the nth cycle of bubble cavitation finishes, the temperature T2n of gas and/or vapor inside the bubble will be:
T
2n
=T
0
+nΔT−nδT=T
0
+n(ΔT−δT) (9)
From equation (8), implosion cycle number ni can be written as follows:
n
i=(Ti−T0−ΔT)/(ΔT−δT)+1 (10)
From equation (10), implosion time τi can be written as follows:
where t1 is a cycle period, and f1 is a frequency of ultra/mega sonic wave.
Based on equations (10) and (11), implosion cycle number ni and implosion time τi can be calculated. Table 1 shows calculated relationships among implosion cycle number ni, implosion time τ1 and (ΔT−δT), assuming Ti=3000° C., ΔT=50.9° C., T0=20° C., and f1=500 KHz, 1 MHz, or 2 MHz.
Detailed processing steps to avoid bubble implosion according to a first embodiment of the present invention are illustrated in
Referring to
According to equations (8) and (9), if (+ΔT−δT) is known, then the implosion time τi can be calculated. But in general, (ΔT−δT) cannot be calculated or directly measured easily. However, τi can be determined empirically.
The above steps 7210 through 7240 can be repeated to narrow down the range of implosion time τi. After knowing the implosion time τi, the time τ1 can be set at a value smaller than 0.5*τi to allow a safety margin. The following paragraph describes an example of such experiment.
Suppose a patterned structure is formed by 55 nm poly-silicon gate lines; ultra sonic wave frequency is 1 MHz generated by a ultra/mega sonic device manufactured by Prosys operating in a gap oscillation mode (disclosed in PCT Application No. PCT/CN2008/073471) for achieving a uniform energy dose within wafer and from wafer to wafer. Other experimental parameters and final pattern damage data are summarized in Table 2 as follows:
In an experiment, when τ1=2 ms (or 2000 cycles), the aforementioned sonic cleaning process introduces as many as 1216 damage sites to the patterned structure with 55 nm feature size. When τ1=0.1 ms (or 100 cycles), the sonic cleaning process introduces zero (0) damage sites to the same patterned structure. So that the τi is a time value between 0.1 ms and 2 ms. Additional tests with narrowed τ1 range can yield a narrower τi range.
In the above experiment, the cycle number depends on ultra or mega sonic power density and frequency: the larger the power density, the less the cycle number is; and the lower the frequency, the less the cycle number is. From the above experiments, a damage-free cycle number can be predicted to be smaller than 2,000 given the power density of ultra or mega sonic wave is larger than 0.1 watts/cm2, and the frequency of ultra or mega sonic wave is equal to or less than 1 MHz. If the frequency increases to a range larger than 1 MHz or the power density is less than 0.1 watts/cm2, it can be predicted that the cycle number will increase.
After acquiring the time period τ1, the time period τ2 can be empirically obtained based on similar DOE method as described above. In this case τ1 is fixed at a predetermined value, and τ2 is gradually shortened in each DOE run until damage on patterned structure is observed. As the time period τ2 is shortened, the temperature of gas and/or vapor inside bubble cannot be cooled down enough, which will gradually increase the average temperature of gas and/or vapor inside the bubble, and eventually trigger an implosion of the bubble. This trigger time is called critical cooling time τc. With knowledge of the critical cooling time τc, the time period τ2 can be set at a value larger than 2*τc to allow a safety margin.
Therefore, parameters of the cleaning process may be determined such that a cleaning effect of imparting the sonic energy causes a yield improvement greater than a yield degradation caused by damages as a result of imparting the sonic energy. A predetermined threshold for the percentage of damages may also be specified, for example by a customer. Parameters of the cleaning process may be determined such that the percentage of damages is lower than the predetermined threshold, or substantially zero, or even zero. The predetermined threshold, for example, may be 10%, 5%, 2%, or 1%. The percentage of damages is substantially zero if the final yield of wafer production is not substantially impacted by any damages caused by the cleaning process. In other words, any damages caused by the cleaning process are tolerable in view of the entire manufacturing process. The percentage of damages can be determined by inspecting a sample wafer using electron microscopy, as discussed above.
A damage site caused by bubble expansion, as illustrated in
Referring again to
Referring again to
Referring to
A saturation point Rs is defined by the largest amount of bubbles that can be contained inside features of the vias 18034, the trench 18036 or another recessed area. When the amount of bubble is over the saturation point Rs, cleaning liquid will be blocked by the bubbles and can hardly reach to the bottom of side walls of the feature of the via 18034 or the trench 18036, so that cleaning performance will be negatively affected. When the amount of bubble is below the saturation point, the clean liquid will have ample availability inside the features of the via 18034 or the trench 18036, hence a good cleaning performance can be achieved.
Below the saturation point, the ratio R of total bubble volume VB to the volume of vias or trenches, or recessed spaces VVTR is:
R=V
B
/V
VTR
<RS
And at the saturation point Rs, the ratio R is
R=V
B
/V
VTR
=Rs
V
B
=N*V
B
As shown in
As shown in
Because the total volume of bubbles in a feature of via or trench is determined by the number and the sizes of the bubbles, controlling the bubble size expansion due to cavitation is critical for the cleaning performance for a wafer with high aspect ratio features.
V
1
=V
0
−ΔV (12)
V
2
=V
1
+δV (13)
V
3
=V
2
−ΔV=V
1
+δV−ΔV=V
0
−ΔV+δV−ΔV=V
0
+δV−2ΔV (14)
where ΔV is a volume compression of the bubble after one compression due to positive pressure generated by ultra/mega sonic wave, and δV is a volume increase of the bubble after one expansion due to negative pressure generated by ultra/mega sonic wave, and (δV−ΔV) is volume increase due to temperature increase (ΔT−δT) as calculated in equation (5) after one time cycle.
After the second cycle of bubble cavitation, the bubble expands to a larger size while the temperature keeps increasing. The volume of V4 of gas and/or vapor inside the bubble will be
V
4
=V
3
+δV=V
0
+δV−2ΔV+δV=V0+2(δV−ΔV) (15)
After the third compression, the volume V5 of gas and/or vapor inside the bubble will be
V
5
=V
4
−ΔV=V
0+2(δV−ΔV)−ΔV=V0+2δV−3ΔV (16)
Following this pattern, when the nth cycle of bubble cavitation reaches the minimum bubble size, the volume V2n−1 of gas and/or vapor inside the bubble will be
V
2n-1
=V
0+(n−1)δV−nΔV=V0+(n−1)δV−nΔV (17)
When the nth cycle of bubble cavitation finishes, the volume V2n of gas and/or vapor inside the bubble will be
V
2n
=V
0
+n(δV−ΔV) (18)
To limit the volume of bubble to a desired volume Vi, which is a dimension with enough physical movement feasibility or the status below the saturation point, and prevent blocking of the path of cleaning liquid exchange in the features of vias, trenches or other recessed areas, the cycle number ni can be written as follows:
n
i=(Vi−V0−ΔV)/(δV−ΔV)+1 (19)
From equation (19), a desired time τi to achieve Vi can be written as follows:
where t1 is a cycle period, and f1 is a frequency of ultra/mega sonic wave. Therefore the desired cycle number ni and the desired time τi for preventing the bubble dimension from reaching a feature blocking level can be calculated from equations (19) and (20).
Note that when the cycle number n of bubble cavitation increases, temperature of gas and/or vapor inside the bubble will increase, therefore more molecules on the bubble surface will evaporate into the inside of the bubble. Therefore the size of the bubble 19082 will further increase and become bigger than value calculated by equation (18). In operation, since the bubble size will be determined by experimental method to be disclosed hereinafter, bubble size impacted by the evaporation of liquid or water into the bubble inner surface due to temperature increase will not be theoretically discussed in detail here. As the average single bubble volume keeps increasing, the ratio R of total bubbles volume VB to the volume of vias, trenches or other recessed spaces VVTR increases from R0 continuously as shown in
As the bubble volume increases, the diameters of the bubbles eventually will reach the same size or same order in size of the feature W1 of the via 18034 as shown in
R=V
B
/V
VTR
=Nv
b
/V
VTR
where the ratio R of total bubble volume VB to the volume of via, trench or recessed space VVTR increases from R0 to Rn, where the average single bubble volume being expanded by the sonic cavitation after a certain cycle number n, in the time τ1. And Rn is controlled below the saturation point Rs,
R
n
=V
B
/V
VTR
=Nv
b
/V
VTR
<Rs.
And the ratio R of total bubble volume VB to the volume of via, trench or other recessed space VVTR decreases from Rn to R0, where the average single bubble volume return to the original size in the cooling process in the time τ2.
Referring to
The cooling state in the time τ2 plays a key role in this cleaning process. And a condition, τ1<τi, to restrict bubble size, is desired. The following method can experimentally determine the time τ2 to shrink bubble size during a cooling down state and the time τ1 to restrict the bubble expansion to the blockage size. The experiment is performed by using an ultra/mega sonic device coupled with a chemical liquid to clean a patterned substrate with small features of vias and trenches, where traceable residues exist to evaluate the cleaning performance.
A first step is to choose a τ1 which is long enough to block the features, which can be used to calculate τi based on the equation (20). A second step is to choose different times τ2 to run DOE. The selection of time τ2 is at least 10 times of τ1, preferably 100 times of τ1 at the first screen test. A third step is to fix time τ1 and fix a power P0 to run under at least five conditions to clean substrates with a specific patterned structure separately. Here, P0 is the power at which the features of vias or trenches on substrate will be surely not cleaned when running on continuous mode (non-pulse mode). A fourth step is to inspect traceable residue status inside the features of vias or trenches of the above five substrates by SEMS or an element analyzer tool such as EDX. The above first to fourth steps can be repeated a few times to gradually shorten the time τ2 till the traceable residues inside the features of vias or trenches are observed. As the time τ2 is shortened, the volume of bubble cannot shrink down enough, which will gradually block the features and influence the cleaning performance. This time is called critical cooling time τc. After acquiring the critical cooling time τc, the time τ2 can be set at a value larger than 2τc to have a safety margin.
A more detail example is shown as follows: a first step is to choose 10 different time τ1 as design of experiment (DOE) conditions, such as τ10, 2τ10, 4τ10, 8τ10, 16τ10, 32τ10, 64τ10, 128τ10, 256τ10, 512τ10, as shown in Table 3 blow. A second step is to choose time τ2 at least 10 times of 512τ10, preferably 20 times of 512τ10 at the first screen test, as shown in Table 3. A third step is to fix a power P0 to run under the above ten conditions to clean substrates with a specific patterned structure separately. Here, P0 is the power at which the features of vias or trenches on substrate will be surely not cleaned when running on continuous mode (non-pulse mode). A fourth step is to use the conditions as shown in Table 3 to process 10 substrates with features of vias or trenches post plasma etching. The reason for choosing post plasma etched substrates is that polymers generated during etching process are formed on sidewalls of trenches and vias. Those polymers formed on the bottoms or side walls of vias are difficult to remove by a conventional method. A next step is to inspect the cleaning status of features of vias or trenches on the ten substrates by SEMS on cross-sections of the substrates. Resulting data are shown in Table 3 below. From Table 3, it becomes clear that the cleaning effect reaches the best point for substrate #6 at τ1=32τ10, therefore the optimum time τ1 is 32τ10.
If there is no peak being found, then the above first to fourth steps can be repeated again with a wider time range of τ1 to find the time τ1. After finding the initial τ1, then the about first and fourth steps can be repeated again with a narrower time range τ1 to narrow down the range of time τ1. After knowing the time τi, the time τ2 can be optimized by reducing the time τ2 from 512 τ2 to a value where the cleaning effect starts to be reduced. A detailed procedure is disclosed as follows in Table 4. From Table 4, the cleaning effect reaches the best point for substrate #5 at τ2=256τ10, therefore the optimum time τ2 is 256τ10.
Since thermal transfer is not exactly uniform in the features, more and more bubble implosion may keep occurring after the temperature reaches Ti. The bubble implosion intensity will become higher and higher while the bubble temperature T increases. However, bubble implosion should be controlled to be below the implosion intensity that would result in damage to the patterned structures. Bubble implosion can be controlled by controlling the temperature Tn to be below the temperature Td by adjusting time Δτ, wherein Tn is the bubble's maximum temperature due to sonic power being applied to the cleaning liquid for n cycles, and Td is the temperature of the accumulation of certain amount of bubble implosion with a high intensity (or power) to result in the patterned structure being damaged. In the present cleaning process, controlling bubble implosion intensity is achieved by adjusting time Δτ after the first bubble implosion starts, so as to achieve a desired cleaning performance and efficiency while avoiding the bubble implosion intensity becomes too high to cause damage to the patterned structures under cleaning.
In order to increase particle removal efficiency (PRE), it is desirable to have a controlled transit cavitation in the ultra or mega sonic cleaning process as shown in
The frequency of ultra or mega sonic wave is another parameter to control the level of implosion. Maintaining a controlled transit cavitation can be achieved by setting a sonic power supply with frequency f1 at a time interval shorter than τ1, and setting the sonic power supply with frequency f2 at a time interval longer than τ2, and repeating the above steps till the wafer is cleaned, where f2 is much higher than f1 and preferably 2 times or 4 times higher. Normally, the higher the frequency is, the lower the level or intensity of the implosion becomes. Again, τ1 is a time interval during which the temperature inside bubble rises higher than a critical implosion temperature; and τ2 is a time interval during which the temperature inside bubble falls down to a temperature much lower than the critical implosion temperature. The controlled transit cavitation will provide a higher PRE (particle removal efficiency) with minimized damage to patterned structures. The critical implosion temperature is the lowest temperature inside bubble which causes the first bubble implosion. In order to further increase the PRE, it is needed to further increase temperature of the bubbles, therefore a longer time τ1 is needed. Also the temperature of bubble can be increased by shortening the time interval τ2. Generally, an ultra or mega sonic wave with the frequency between 0.1 MHz-10 MHz may be applied to the wafer cleaning processes disclosed in the present invention.
In the above embodiments, if all the critical process parameters of sonic power supply, such as power level, frequency, power-on time (τ1) and power-off time (τ2) are preset in a power supply controller without real-time monitoring during a wafer cleaning process, damages to patterned structures may still occur due to some abnormal conditions during the wafer cleaning process. Hence, there is a need for an apparatus and method for real-time monitoring of the sonic power supply operation status. If the parameters are not in the normal range, the sonic power supply should be shut down and an alarm signal should be sent out and reported.
Vout=(R2/R1)*Vin
assuming R1=200 k,R2=R3=R4=10 K,Vout=(R2/R1)*Vin=Vin/20
where Vout is amplitude value output by the voltage attenuation circuit 26090, Vin is amplitude value input to the voltage attenuation circuit 26090, and R1, R2, R3, R4 are resistances of the two operational amplifiers 28102 and 28104.
τ1=Counter_H*20 ns, and τ2=Counter_L*20 ns.
where Counter_H is the number of high level, Counter_L is the number of low level.
The main controller 26094 compares the calculated power-on time with a preset time τ1. If the calculated power-on time is longer than the preset time τ1, the main controller 26094 sends out an alarm signal to the host computer 25080. The host computer 25080, upon receiving the alarm signal, shuts down the sonic generator 25082. The main controller 26094 compares the calculated power-off time with a preset time τ2. If the calculated power-off time is shorter than the preset time τ2, the main controller 26094 sends out an alarm signal to the host computer 25080. The host computer 25080, upon receiving the alarm signal, shuts down the sonic generator 26082. In an embodiment, the main controller 26094 can be implemented using an Altera Cyclone IV FPGA model number EP4CE22F17C6N.
In some embodiments, the wafer cleaning processes depicted in various figures throughout the present disclosure can be combined to produce a desired cleaning result. In one embodiment, the amplitude detection in step 34030 in
The present invention provides an apparatus for cleaning semiconductor substrate using ultra/mega sonic device, comprising a chuck, an ultra/mega sonic device, at least one nozzle, an ultra/mega sonic power supply, a host computer, and a detection system. The chuck holds a semiconductor substrate. The ultra/mega sonic device is positioned adjacent to the semiconductor substrate. The at least one nozzle injects chemical liquid on the semiconductor substrate and in a gap between the semiconductor substrate and the ultra/mega sonic device. The host computer sets the ultra/mega sonic power supply at frequency f1 and power P1 to drive the ultra/mega sonic device; before bubble cavitation in the liquid damaging patterned structure on the semiconductor substrate, sets the ultra/mega sonic power supply at zero output; and after temperature inside bubble cooling down to a set temperature, sets the ultra/mega sonic power supply at frequency f1 and power P1 again. The detection system detects power on time at power P1 and frequency f1 and power off time separately, and compares the detected power on time at power P1 and frequency f1 with a preset time τ1. If the detected power on time is longer than the preset time τ1, the detection system sends out an alarm signal to the host computer, and the host computer receives the alarm signal and shuts down the ultra/mega sonic power supply. The detection system also compares the detected power off time with a preset time τ2. If the detected power off time is shorter than the preset time τ2, the detection system sends out an alarm signal to the host computer, and the host computer receives the alarm signal and shuts down the ultra/mega sonic power supply.
In an embodiment, the ultra/mega sonic device is further coupled with the nozzle and positioned adjacent to the semiconductor substrate, and the energy of the ultra/mega sonic device is transmitted to the semiconductor substrate through the liquid column out of the nozzle.
The present invention provides another apparatus for cleaning semiconductor substrate using ultra/mega sonic device, comprising a chuck, an ultra/mega sonic device, at least one nozzle, an ultra/mega sonic power supply, a host computer, and a detection system. The chuck holds a semiconductor substrate. The ultra/mega sonic device is positioned adjacent to the semiconductor substrate. The at least one nozzle injects chemical liquid on the semiconductor substrate and in a gap between the semiconductor substrate and the ultra/mega sonic device. The host computer sets the ultra/mega sonic power supply at frequency f1 and power P1 to drive the ultra/mega sonic device; before bubble cavitation in the liquid damaging patterned structure on the semiconductor substrate, sets the ultra/mega sonic power supply at zero output; after temperature inside bubble cooling down to a set temperature, sets the ultra/mega sonic power supply at frequency f1 and power P1 again. The detection system detects amplitude of each waveform output by the ultra/mega sonic power supply, and compares detected amplitude of each waveform with a preset value. If the detected amplitude of any waveform is larger than the preset value, the detection system sends out an alarm signal to the host computer, and the host computer receives the alarm signal and shuts down the ultra/mega sonic power supply, wherein the preset value is larger than a waveform amplitude at normal operation.
In an embodiment, the ultra/mega sonic device is further coupled with the nozzle and positioned adjacent to the semiconductor substrate, and the energy of the ultra/mega sonic device is transmitted to the semiconductor substrate through the liquid column out of the nozzle.
The present invention provides another apparatus for cleaning semiconductor substrate using ultra/mega sonic device, comprising a cassette, a tank, an ultra/mega sonic device, at least one inlet, an ultra/mega sonic power supply, a host computer, and a detection system. The cassette holds at least one semiconductor substrate. The tank holds the cassette. The ultra/mega sonic device is attached to an outside wall of the tank. The at least one inlet is used for filling chemical liquid into the tank to immerse the semiconductor substrate. The host computer sets the ultra/mega sonic power supply at frequency f1 and power P1 to drive the ultra/mega sonic device; before bubble cavitation in the liquid damaging patterned structure on the semiconductor substrate, sets the ultra/mega sonic power supply at zero output; after temperature inside bubble cooling down to a set temperature, sets the ultra/mega sonic power supply at frequency f1 and power P1 again. The detection system detects power on time at power P1 and frequency f1 and power off time separately, and compares the detected power on time at power P1 and frequency f1 with a preset time τ1. If the detected power on time is longer than the preset time τ1, the detection system sends out an alarm signal to the host computer, and the host computer receives the alarm signal and shuts down the ultra/mega sonic power supply. The detection system also compares the detected power off time with a preset time τ2. If the detected power off time is shorter than the preset time τ2, the detection system sends out an alarm signal to the host computer, and the host computer receives the alarm signal and shuts down the ultra/mega sonic power supply.
The present invention provides another apparatus for cleaning semiconductor substrate using ultra/mega sonic device, comprising a cassette, a tank, an ultra/mega sonic device, at least one inlet, an ultra/mega sonic power supply, a host computer and a detection system. The cassette holds at least one semiconductor substrate. The tank holds the cassette. The ultra/mega sonic device is attached to an outside wall of the tank. The at least one inlet is used for filling chemical liquid into the tank to immerse the semiconductor substrate. The host computer sets the ultra/mega sonic power supply at frequency f1 and power P1 to drive the ultra/mega sonic device; before bubble cavitation in the liquid damaging patterned structure on the semiconductor substrate, setting the ultra/mega sonic power supply at zero output; after temperature inside bubble cooling down to a set temperature, setting the ultra/mega sonic power supply at frequency f1 and power P1 again. The detection system detects amplitude of each waveform output by the ultra/mega sonic power supply, and compares detected amplitude of each waveform with a preset value. If detected amplitude of any waveform is larger than the preset value, the detection system sends out an alarm signal to the host computer, and the host computer receives the alarm signal and shuts down the ultra/mega sonic power supply, wherein the preset value is larger than a waveform amplitude at normal operation.
While this disclosure has been particularly shown and described with references to exemplary embodiments thereof, it shall be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit of the claimed embodiments.
This is a continuation-in-part application based on PCT International Patent Application Nos. PCT/CN2015/079015 filed May 15, 2015, PCT/CN2015/079342 filed May 20, 2015, PCT/CN2016/078510 filed Apr. 6, 2016, PCT/CN2016/099303 filed Sep. 19, 2016, and PCT/CN2016/099428 filed Sep. 20, 2016, the entire contents of which are incorporated herein by reference.
| Number | Date | Country | |
|---|---|---|---|
| Parent | 15814242 | Nov 2017 | US |
| Child | 17470713 | US |
| Number | Date | Country | |
|---|---|---|---|
| Parent | 17470713 | Sep 2021 | US |
| Child | 18181074 | US |
| Number | Date | Country | |
|---|---|---|---|
| Parent | PCT/CN2016/099428 | Sep 2016 | US |
| Child | 15814242 | US | |
| Parent | PCT/CN2016/099303 | Sep 2016 | US |
| Child | PCT/CN2016/099428 | US | |
| Parent | PCT/CN2016/078510 | Apr 2016 | US |
| Child | PCT/CN2016/099303 | US | |
| Parent | PCT/CN2015/079342 | May 2015 | US |
| Child | PCT/CN2016/078510 | US | |
| Parent | PCT/CN2015/079015 | May 2015 | US |
| Child | PCT/CN2015/079342 | US |
