Patent Application
20120067847
This application is based upon and claims the benefit of priority from prior Japanese Patent Application No. 2010-212632, filed Sep. 22, 2010, the entire contents of which are incorporated herein by reference.
Embodiments described herein relate generally to an apparatus and a method of processing a substrate such as a semiconductor wafer or a glass substrate.
In an apparatus which performs wet etching on a substrate such as a semiconductor wafer or a glass substrate, oxide films on the substrate are removed by supplying the substrate with an etching solution while rotating the substrate. After an etching treatment, a rinsing treatment with pure water and drying are performed.
In general, according to one embodiment, an apparatus of processing a substrate including first and second surfaces includes a treatment chamber, a holder, a first feed device, and a temperature control device. The holder is provided in the treatment chamber and is configured to rotatably hold the substrate. The first feed device includes a first nozzle configured to eject an etching solution to the first surface of the substrate held by the holder. The temperature control device includes a first device, a second device, and a controller. The first device is configured to heat and/or cool an atmosphere inside the treatment chamber. The second device is configured to heat and/or cool the etching solution. The controller is configured to control operation of the first and second devices such that a temperature of the atmosphere is higher than a temperature of the etching solution in the first nozzle and that difference between the temperature of the atmosphere and the temperature of the etching solution is maintained constant.
According to another embodiment, an apparatus of processing a substrate including first and second surfaces includes a treatment chamber, a holder, a first feed device, and a temperature control device. The holder is provided in the treatment chamber and is configured to rotatably hold the substrate. The first feed device includes a first nozzle configured to eject an etching solution to the first surface of the substrate held by the holder. The temperature control device includes a shielding member, a second device, and a controller. The shielding member is placed such that the shielding member is opposed to the first surface of the substrate and forms a space having a layer shape between the first surface and the shielding member, and the shielding member includes a first device configured to heat and/or cool gas in the space. The second device is configured to heat and/or cool the etching solution. The controller is configured to control operation of the first and second devices such that a temperature of the gas is equal to or higher than a temperature of the etching solution in the nozzle.
According to further another embodiment, a method of processing a substrate comprising first and second surfaces in a treatment chamber includes at least partially etching the first surface by supplying an etching solution to the first surface with rotating the substrate; and controlling a temperature of the etching solution and a temperature of an atmosphere inside the treatment chamber such that the temperature of the atmosphere is higher than the temperature of the etching solution and that difference between the temperature of the etching solution and the temperature of the atmosphere is maintained constant.
Various embodiments will be described hereinafter with reference to the accompanying drawings.
The apparatus of processing shown in
At a bottom part inside the treatment chamber 1, for example, a columnar block 2 is provided to be vertically movable. The columnar block 2 is, for example, rotatable about an axis in parallel with a height direction thereof by a motor not shown.
A cylindrical rotary shaft 3 is attached to the block 2. Here, the rotary shaft 3 has a cylindrical shape and penetrates to the columnar block 2 along the height direction thereof. The rotary shaft 3 is used as a third nozzle and a fourth nozzle which are explained below.
A vacuum chuck 4 is provided on a top face of the block 2. The vacuum chuck 4 holds a substrate, for example, a semiconductor wafer 36 by suction. Here, the top surface and a bottom surface of the wafer 36 held by the vacuum chuck 4 are a first surface and a second surface, respectively.
An inner cup 5 and an outer cup 6 each have a cylindrical shape, an upper part of which is bent toward inside of the cup, and they are provided and nested to stand on the bottom part of the chamber 1 such that they encircle the block 2. A top end of the outer cup 6 is positioned at a higher position than a top end of the inner cup 5.
An annular space between the columnar block 2 and the inner cup 5 functions as an area for collecting an etching solution scattered from the wafer 36 rotating during etching. The etching solution scattered to the annular space is recovered through a recovery line 7 connected to the bottom part of the chamber 1. An annular space between the inner cup 5 and the outer cup 6 functions as a liquid receiver portion which receives a rinse solution scattered from the wafer 36 rotating during a rinsing treatment. The rinse solution scattered to the annular space is discharged through a drain line 8 connected to the bottom part of the chamber 1.
To the chamber 1, a first device 9 is connected through a High Efficiency Particulate Air (HEPA) filter 10 and a feed line 11. The chamber 1 and the first device 9 are connected to each other through a return line 12.
The first device 9 includes a heater and/or a cooler and heats and/or cools an atmosphere inside the chamber 1. The first device 9 may further include a humidification function. The first device 9 takes in a gas from the inside of the treatment chamber 1 through the return line 12, heats and/or cools the gas, and arbitrarily humidifies the gas. Thereafter, the first device 9 returns the gas to the treatment chamber 1 through the feed line 11 and the filter 10. As the first device 9, an air conditioner, for example, a water-cooling air conditioner capable of precisely controlling a temperature can be used. The following explanation will be made assuming that the first device 9 has a function which heats and humidifies the gas.
A first temperature sensor 13 and a humidity sensor 14 are provided inside the chamber 1. The first temperature sensor 13 and the humidity sensor 14 are each connected to a controller 38. To the controller 38, the first device 9 is further connected.
The first device 9, the first temperature sensor 13, and the controller 38 perform temperature adjustment of the atmosphere inside the chamber 1. Specifically, the sensor 13 detects an atmospheric temperature inside the chamber 1, and outputs a detection signal to the controller 38. The controller 38 controls operation of the first device 9 based on output from the sensor 13. For example, the controller 38 performs a feedback control, using the output from the sensor. According to an example, the controller 38 controls operation of the first device 9 so as to minimize an absolute value of difference between an actually measured temperature obtained from the output of the sensor 13 and a preset temperature.
The first device 9, the humidity sensor 14, and the controller 38 perform humidity adjustment inside the chamber 1. Specifically, the sensor 14 detects the humidity inside the chamber 1 and outputs a detection signal to the controller 38. The controller 38 controls operation of the first device 9 based on output from the sensor 14. For example, the controller 38 performs a feedback control, using the output from the sensor 14. According to an example, the controller 38 controls operation of the first device 9 so as to minimize an absolute value of difference between the actually measured humidity and preset humidity.
The apparatus of processing further include a first feed device.
The first feed device includes a tank 16, a first nozzle 15, a first conduit, and a pump 39.
The tank 16 contains an etching solution. For example, a fluorinated acid- or hydrofluoric acid-based solution may be used as the etching solution.
The first nozzle 15 is provided to be positioned above the center of the wafer 36 held by the vacuum chuck 4. The first nozzle 15 ejects the etching solution to the first surface of the wafer 36. For example, the first nozzle 15 is movable along a radial direction of the wafer 36.
The first conduit functions to connect liquid between the tank and the first nozzle 15. Here, the first conduit is a first feed line 17 which is provided between the tank 16 and the first nozzle 15.
A pump 39 is provided on the first conduit. The pump 39 pumps the etching solution from the tank 16 and supplies the solution to the nozzle 15 through the line 17.
The first feed device further includes a third nozzle 3, a second conduit, and a pump 40.
The third nozzle is the rotary shaft 3, as is described above. The third nozzle 3 ejects the etching solution to the second surface of the wafer 36.
The second conduit functions to connect liquid between the tank 16 and the nozzle 3. Here, the second conduit includes a second feed line 18, a valve 20, and a main line 19. One end of the second feed line 18 is connected to the tank 16, and the other end is connected to one end of the main line 19 through the valve 20. The other end of the main line 19 is connected to the bottom end of the nozzle 3.
The pump 40 is provided on the second conduit. The pump 40 pumps the etching solution from the tank 16 and supplies the solution to the nozzle 3 through the second feed line 18, the valve 20, and the main line 19.
The third nozzle, the second conduit and the pump 40 may be omitted.
For example, under control by the controller 38, the first feed device guides the etching solution from the tank 16 to the first nozzle 15 through the line 17 by the pump 39 while moving the first nozzle 15 along the radial direction of the wafer 36, and the etching solution is ejected to the first surface of the wafer 36 from the nozzle 15. At this time, the first feed device guides the etching solution from the tank 16 to the nozzle 3 through the line 18, the valve 20, and the line 19 by the pump 40, and the etching solution is ejected to the second surface of the wafer 36 from the nozzle 3.
To the tank 16 of the first feed device, a second device 21 is connected through circulation lines 22 and 23. The second device 21 includes a pump, and it takes in the etching solution from the tank 16 through the line 22 and returns the solution to the tank 16 through the line 23.
The second device 21 further includes a heater and/or a cooler, and heats and/or cools the etching solution which has been taken in. As the heater and/or the cooler, for example, an air-cooling and water-cooling temperature regulator using a peltier element and circulation fluid can be used. The second device 21 may not heat or cool the etching solution inside the tank 16. For example, the second device 21 may be configured to heat and/or cool the etching solution inside the line 18 or 19, or the nozzle 3.
In the tank 16, a second temperature sensor 24 is provided. The second temperature sensor 24 is connected to the controller 38. To the controller 38, the second device 21 is further connected.
The second device 21, the second temperature sensor 24, and the controller 38 perform temperature adjustment of the etching solution in the tank 16. Specifically, the sensor 24 detects a temperature of the etching solution in the tank 16 and outputs a detection signal to the controller 38. The controller 38 controls operation of the second device 21 based on output from the sensor 24. For example, the controller 38 performs a feedback control, using output from the sensor 24. According to one example, the controller 38 controls operation of the second device 21 so as to minimize an absolute value of difference between an actually measured temperature obtained from the output of the sensor 24 and a preset temperature.
The apparatus of processing further includes a second feed device.
The second feed device includes a tank 26, a second nozzle 25, a third conduit, and a pump 41.
The tank 26 contains the rinse solution. For example, the rinse solution is pure water.
The second nozzle 25 is provided to be positioned above the center of the wafer held by the vacuum chuck 4 inside the treatment chamber 1. The second nozzle 25 ejects the rinse solution to the first surface of the wafer 36. The second nozzle 25 is movable along a radial direction of the wafer 36.
The third conduit functions to connect liquid between the tank 26 and the second nozzle 25. Here, the third conduit is a third feed line 27 which is provided between the tank 26 and the second nozzle 25.
The pump 41 is provided on the third conduit. The pump 41 pumps the rinse solution from the tank 26 and supplies the solution to the nozzle 25 through the line 27.
The second feed device further includes a fourth nozzle, a fourth conduit, and a pump 42.
The fourth nozzle is the rotary shaft 3, as is described above. The fourth nozzle 4 ejects the rinse solution to the second surface of the wafer 36.
The fourth conduit functions to connect liquid between the tank 26 and the nozzle 3. The fourth conduit includes a fourth feed line 28, a valve 29, and the main line 19. One end of the fourth feed line 28 is connected to the tank 26, and the other end is connected to one end of the main line 19 through the valve 29. The other end of the main line 19 is connected to the bottom end of the nozzle 3.
A pump 42 is provided on the fourth conduit. The pump 42 pumps the etching solution from the tank 26 and supplies the solution to the nozzle 3 through the fourth feed line 28, the valve 29, and the main line 19.
The fourth nozzle, the fourth conduit, and the pump 42 may be omitted.
For example, under control by the controller 38, the second feed device guides the rinse solution from the tank 26 to the nozzle 25 through the line 27 by the pump 41 while moving the second nozzle 25 along the radial direction of the wafer 36, and the rinse solution is ejected to the first surface of the wafer 36 from the nozzle 25. At this time, the second feed device guides the rinse solution from the tank 26 to the nozzle 3 through the line 28, the valve 29, and the line 19 by the pump 42, and the etching solution is ejected to the second surface of the wafer 36 from the nozzle 3.
To the tank 26 of the second feed device, a third device 30 is connected through circulation lines 31 and 32. The third device 30 includes a pump, and it takes in the rinse solution from the tank 26 through the line 32 and returns the solution to the tank 26 through the line 31.
The third device 30 further includes a heater and/or a cooler, and heats and/or cools the rinse solution which has been taken in. As the heater and/or the cooler, for example, an air-cooling and water-cooling temperature regulator using a peltier element and circulation fluid can be used. The third device 30 may not heat or cool the rinse solution inside the tank 26. For example, the third device 30 may be configured to heat and/or cool the rinse solution inside the line 28 or 19, or the nozzle 3.
Inside the tank 26, a third temperature sensor 33 is provided. The third temperature sensor 33 is connected to the controller 38. To the controller 38, the third device 30 is further connected.
The third device 30, the third temperature sensor 33, and the controller 38 perform temperature adjustment of the rinse solution in the tank 26. Specifically, the sensor 33 detects a temperature of the rinse solution in the tank 26 and outputs a detection signal to the controller 38. The controller 38 controls operation of the third device 30 based on output from the sensor 33. For example, the controller 38 performs a feedback control, using output from the sensor 33. According to an example, the controller 38 controls operation of the third device 30 so as to minimize an absolute value of difference between an actually measured temperature obtained from the output of the sensor 33 and a preset temperature.
The apparatus of processing further includes a blower 44. The blower 44 includes a nozzle 34, a line 35, and a blower main body 43. The nozzle 34 is positioned above the wafer 36 held by the vacuum chuck 4 inside the treatment chamber 1 such that it blows dry gas such as dry nitrogen to the wafer 36 from an upper tilted direction. The line 35 is provided between the nozzle 34 and the blower main body 43 provided outside the chamber 1 and connects them, and it guides the dry gas from the blower main body 43 to the nozzle 34.
Next, a method of processing a substrate, for example a semiconductor wafer 36, according to the first embodiment, will be described referring to the processing apparatus as described above.
At first, a substrate such as a semiconductor wafer 36 is held by the vacuum chuck 4. Typically, the atmosphere of the chamber is substituted by inert gas such as nitrogen gas in advance.
Subsequently, under control by the controller 38 the first device 9 and the second device 21 are operated to adjust a temperature of the gas inside the treatment chamber 1 and a temperature of the etching solution. Specifically, the temperatures are controlled such that the atmospheric temperature inside the treatment chamber 1 is higher than the temperature of the etching solution and difference between these temperatures is maintained constant. For example, when the temperature of the etching solution is set within the range of 22 to 24° C., the target temperature of the atmosphere inside the chamber 1 is set to be 1.5 to 8° C. higher than the temperature of the etching solution. When the temperature of the etching solution is set to be higher, for example, at 25° C. or more, preferably within a range of 27 to 35° C., the target temperature of the atmosphere inside the chamber 1 is set to be 1 to 15° C. higher than that of the etching solution. If difference between the atmospheric temperature inside the chamber 1 and the temperature of the etching solution is small, it is difficult to improve the in-plane uniformity of etching of the wafer.
Preferably, in addition to the temperature adjustment described above, the humidity of the atmosphere inside the chamber 1 is controlled by the controller 38 and the first device 9. For example, control is performed such that the relative humidity of the atmosphere inside the chamber 1 so as to be within a range of 90 to 100%.
Next, the vacuum chuck 4 holding the wafer 36 is rotated, and then the etching solution is ejected from the first nozzle 15 to the wafer 36 with moving the first nozzle 15 along the radial direction of the wafer 36 to treat the surface of the wafer 36. For example, oxide film is removed from the surface of the wafer 36.
The etching solution on the wafer 36 is outwardly transferred from the center of the wafer 36 due to centrifugal force, and then scatters along the radial direction of the wafer 36. At this time, if the height of the block 2 is controlled such that the top surface of the wafer 36 is lower than the height of the top end of the inner cup 5, the scattered etching solution is collected in the annular space between the columnar block 2 and the inner cup 5 and is recovered through a recovery line 7 which is connected to the bottom part of the chamber 1.
In this method, temperature reduction of the wafer 36 or the etching solution thereon caused by vaporization of the etching solution is small, since the atmospheric temperature inside the chamber 1 is controlled to be higher than the temperature of the etching solution. Therefore, breadth of temperature distribution occurring due to the evaporation of the etching solution on the surface of the wafer 36, that is, temperature difference between the center of the wafer 36 and the periphery thereof is minimized, and thereby the in-plane uniformity of the etching of the wafer 36 can be improved.
In particular, when an etching speed is increased by using a heated etching solution, the breadth of temperature distribution caused by the vaporization of the etching solution on the surface of the wafer 36 becomes broad compared to a case of using the etching solution at a room temperature. According to the above-mentioned method, even in the case of using the heated etching solution, the breadth of temperature distribution can be sufficiently diminished, and the in-plane uniformity of the wafer 36 can be improved.
According to this method, as is described above, the atmosphere inside the chamber 1 is preferably humidified. When the atmospheric temperature inside the chamber 1 is increased, vaporization of the etching solution on the surface of the wafer 36 is accelerated. When the humidity inside the chamber 1 is increased, the vaporization of the etching solution can be restrained, and thus the breadth of the temperature distribution caused by the vaporization of the etching solution on the surface of the wafer 36 can be diminished.
When a solvent contained in the etching solution, for example, water is vaporized on the surface of the wafer 36, a concentration of the etching solution is increased. If the breadth of concentration distribution is broad, ununiformity of etching occurs due to the breadth. Excess increase of the concentration of the etching solution can be prevented by humidifying the atmosphere inside the chamber 1.
Therefore, if the atmosphere inside the chamber 1 is humidified, etching can be achieved with better uniformity compared to a case where the atmosphere is not humidified.
While the first surface of the wafer 36 is subjected to etching, the etching solution can be supplied to the second surface of the wafer 36 as well. Namely, the pump 40 may be operated in condition that a valve 29 is closed and a valve 20 is open. Thereby, the etching solution is pumped from the tank 16 and is supplied to the nozzle 3 through the line 18, the valve 20, and the line 19, and is ejected to the second surface of the wafer from the nozzle 3.
If the etching solution is not supplied to the second surface of the wafer 36, the etching solution supplied to the first surface of the wafer flows to a periphery portion of the second surface of the wafer 36, and etching may occur in the periphery portion. In this case, the periphery portion of the wafer 36 becomes thinner than the central portion of the wafer.
If the etching solution is supplied to the second surface of the wafer 36 while the first surface of the wafer 36 is subjected to etching, occurrence of the thickness ununiformity of the wafer 36 can be avoided. Here, difference between the atmospheric temperature inside the chamber 1 and the temperature of the etching solution supplied to the second surface of the wafer 36 is within the range described above and is maintained constant, since the temperature of the etching solution in the tank 16 is controlled as is described above. Therefore, the ununiformity of thickness due to the supply of the etching solution to the second surface cannot occur.
Subsequently, supply of the etching solution to the wafer 36 is stopped. The top surface of the wafer 36 held by the vacuum chuck 4 is then positioned to be higher than the top end of the inner cup 5 and lower than the top end of the outer cup 6 by moving the block 2 upwardly. While the wafer 36 is kept rotated, the pump 41 is operated to supply the etching solution, for example, pure water from the tank 26 to the second nozzle 25 through the first feed line 27 and eject it to the wafer 36 from the nozzle 25. Thereby, the etching solution on the wafer 36 is rinsed out.
The rinse solution on the wafer 36 is outwardly transferred from the center of the wafer 36 due to centrifugal force, and then scatters along the radial direction of the wafer 36. The scattered rinse solution is collected in the annular space between the inner cup 5 and the outer cup 6, and can be recovered through the drain line 8 which is connected to the bottom part of the chamber 1.
In this rinsing treatment, the temperature of the rinse solution inside the tank 26 is controlled, for example, to be equal to or higher than the temperature of the etching solution. In the rinsing treatment performed subsequent to the etching treatment, residual etching solution may etch the surface of the wafer 36.
If the rinse solution having a lower temperature than that of the etching solution is supplied to the wafer, the etching solution is cooled by the rinse solution. However, the cooling of the etching solution does not occur uniformly within the surface of the wafer 36. The etching speed is varied in accordance with the temperature of the etching solution. Therefore, the wafer 36 cannot be etched uniformly, and the thickness of the wafer 36 may become ununiform. As is described above, in this method, the temperature of the rinse solution is controlled to be equal to or higher than that of the etching solution. Therefore, the ununiform cooling of the residual etching solution on the wafer 36 and ununiformity of the etching speed caused thereby can be avoided, and thus occurrence of the thickness ununiformity of the wafer 36 can be also avoided.
When the etching solution is supplied to the second surface of the wafer 36 as well, the rinse solution may be also supplied to the second surface of the wafer 36 in the rinsing treatment of the wafer 36. Namely, in condition that a valve 20 is closed and a valve 29 is open, the pump 42 may be operated to pump the rinse solution, for example, pure water from the tank 26 and supply to the nozzle 3 through the line 28, the valve 29, and the line 19, to eject it to the second surface of the wafer from the nozzle 3. Thereby, the etching solution on the second surface of the wafer 36 is rinsed out.
Difference between the temperature of the etching solution supplied to the second surface of the wafer 36 and that of the rinse solution is, for example, within the range described above and is maintained constant. In this case, occurrence of etching ununiformity due to the residual etching solution can be avoided, and thus thickness ununiformity of the wafer 36 cannot occur.
Subsequently, supply of the rinse solution is stopped. Then, while the wafer 36 is maintained, dry gas is supplied to the nozzle 34 from the blower main body 43 through the line 35 and is blown to the wafer 36 from the nozzle 34. Thereby the wafer 36 is dried. Here, the dry gas is, for example, dry nitrogen.
By thus blowing dry gas to the wafer 36, the humidity near the wafer 36 can be decreased, and the drying time can be shortened.
According to the first embodiment as described above, in the etching of the substrate, the etching speed can be accelerated and simultaneously in-plane uniformity occurring between the center of the substrate and the periphery thereof can be avoided.
In the apparatus of processing a substrate shown in
The shielding member 37 includes a plate 45 and a first device 9.
For example, the plate 45 has an approximate same size as that of the wafer 36. According to an example, the plate 45 has, for example, a disc shape with a thickness of 5 to 10 mm, and is made of polytetrafluoroethylene.
The first device 9 heats and/or cools the gas in the space between the shielding member 37 and the wafer 36. The first device 9 is, for example, a heater. The first device 9 may be, for example, provided to be adjacent to the plate 45, or may be built in the plate 45. Here, the first device 9 is assumed to be a heater Which is built in the plat body 45.
The shielding member 37 is provided with two through holes. The inner walls of the through holes each are provided with an insulating material having a ring form. The nozzle 15 and 25 penetrate the shielding member 37 through the through holes.
The first temperature sensor not shown is connected to the controller 38. In this embodiment, the first temperature sensor is, for example, held by the shielding member 37, and it detects a temperature of the space formed between the shielding member 37 and the wafer 36 and having a layer shape and outputs a detection signal to the controller 38. For example, the first temperature sensor may be provided on a surface of the shielding member opposed to the wafer 36, on a back surface of the aforementioned surface, or the like, to detect a temperature of the shielding member 37 itself and output the detection signal to the controller 38.
The heater 9, the first temperature sensor, and the controller 38 perform temperature adjustment of the gas in the space formed between the shielding member 37 and the wafer 36 and having a layer shape. Specifically, the temperature sensor detects the temperature of the space formed between the shielding member 37 and the wafer 36 and outputs a detection signal to the controller 38. The controller 38 controls the operation of the heater 9 based on the outputs from the temperature sensor. For example, the controller 38 performs feedback control using the outputs from the first temperature sensor. According to an example, the controller 38 controls operation of the heater 9 so as to minimize an absolute value of difference between an actually measured temperature obtained from the output of the first temperature sensor and a preset temperature of the heater 9.
The nozzle 34 can be moved vertically and horizontally in the treatment chamber 1. Thus, when the wafer 36 is dried, dry gas can be blown to the substrate by moving the shielding member 37 upwardly and then positioning the nozzle 34 between the wafer 36 and the shielding member 37.
Described next is a method of processing a substrate by using the processing apparatus as described above, according to the second embodiment.
The method according to the second embodiment is the same as the method according to the first embodiment, except that the breadth of the temperature of the etching solution on the wafer 36, that is, the temperature difference between the center of the wafer 36 and the periphery thereof is minimized with use of the shielding member 37. The temperature of the space formed between the shielding member 37 and the wafer 36 and having a layer shape is controlled to be equal to or higher than that of the etching solution. The reason why the temperature of the space may be equal to that of the etching solution is that more precise temperature adjustment is achieved since the first device 9 adjusts a temperature of a smaller space compared to the first embodiment.
The temperature adjustment is performed as described above, and thus temperature reduction of the wafer 36 or the etching solution thereon due to the vaporization of the etching solution is smaller. Therefore, the breadth of the temperature distribution caused by the vaporization of the etching solution on the surface of the wafer 36, that is, temperature difference between the center of the substrate and the periphery thereof is minimized. Thus, the in-plane uniformity in the surface of the wafer 36 can be improved.
According to the second embodiment as described above, the etching speed can be accelerated in the etching of the substrate, and simultaneously the thickness ununiformity occurring between the center of the substrate and the periphery thereof can be avoided.
Although a semiconductor wafer is used as a substrate in each of the first and second embodiments, other substrates such as a glass substrate may be used.
Hereinafter, more concrete examples will now be described referring to the processing apparatuses described above.
In the processing apparatus as shown in
The wafer 36 having a radius of 150 nm was held by the vacuum chuck 4. As the wafer 36, a wafer with temperature detection chips buried along the radial direction was used. Then, while rotating the wafer 36, pure water was ejected from the first nozzle 15 to the wafer 36, and temperature was measured by the temperature detection chips from the center of the wafer 36 to the periphery thereof. Conditions for measurement are indicted below.
Rotation speed of wafer 36: 500 rpm
Ejection amount of pure water: 1.5 to 2.0 L/min
Atmospheric temperature inside chamber 1: 24.1° C.
Temperature of pure water: 22.5° C., 24.5° C., and 26.5° C.
Ejection period of pure water per wafer: 20 seconds
Results are shown in
Next, uniformity of etching was studied. The same treatment described above was performed except that an etching solution and a wafer having thermally oxidized film were used in place of pure water and the wafer with the buried temperature detection chips. The etching solution used herein is an aqueous solution containing 3 wt % of ammonium hydrogen fluoride, 34 wt % of aluminum fluoride solution, and maximum 1 wt % of a surfactant, and pure water.
The uniformity of etching was obtained by carrying out the measurement described below before and after the aforementioned treatment.
First, thickness of the thermally oxidized film of a wafer not being subjected to etching was measured with respect to four diameter directions with use of an optical interferotype spectroscopic ellipsometer. Next, relationship between distance from the center of the wafer and thickness of the thermally oxidized film was obtained by averaging the data obtained thereby. Subsequently, the wafer was subjected to etching treatment and, after 20 seconds from beginning of the etching, the same measurement as described above was carried out. Then, for each distance from the center of the wafer, difference between thickness of the thermally oxidized film before etching and that of the film after etching was calculated as an etching amount. The procedure mentioned above was repeated four times, and the average of the data obtained thereby was calculated. From the data, a maximum etching amount, a minimum etching amount, and an average etching amount were obtained, and difference between the maximum etching amount and the minimum etching amount was divided by the average etching amount. The value obtained thereby was etching uniformity. The results are shown in Table 1.
As is apparent from Table 1, in Example 1 in which the atmospheric temperature inside the chamber 1 was higher than the temperature of the etching solution, in-plane etching uniformity of the wafer was improved compared with Examples 2 and 3 in which the atmospheric temperature inside the chamber 1 was lower than the temperature of the etching solution.
While certain embodiments have been described, these embodiments have been presented by way of example only, and are not intended to limit the scope of the inventions. Indeed, the novel embodiments described herein may be embodied in a variety of other forms; furthermore, various omissions, substitutions and changes in the form of the embodiments described herein may be made without departing from the spirit of the inventions. The accompanying claims and their equivalents are intended to cover such forms or modifications as would fall within the scope and spirit of the inventions.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2010-212632 | Sep 2010 | JP | national |
