JP2001144006A - Method for removing resist - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve etching rate and shorten a treatment time in a method for removing a resist film which used ozone dissolving water. SOLUTION: Chemical liquid capable of turning to ozonolysis catalyst such as aqueous ammonia and hydrogen peroxide water is added together with ozone dissolving water on a wafer wherein a resist film is formed on the upper surface. As a result, etching rate can be improved without increasing temperature of the ozone dissolving water.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for removing a resist, and more particularly to a method for removing a resist film (organic film) formed on a semiconductor substrate using ozone-dissolved water.

[0002]

2. Description of the Related Art In a lithography process which is one of semiconductor device manufacturing processes, a resist is generally used as a patterning mask. This resist film needs to be removed when the patterning of the semiconductor device is completed. To remove the resist film, the SPM (Sulfuric-acid Hydrogen-Peroxide Mixture) usually heated to 100 ° C or higher
: A mixed solution of sulfuric acid and hydrogen peroxide (hereinafter referred to as SPM) or an organic solvent. Since the resist removal by SPM is performed at a high temperature of 100 ° C. or higher, it is general to use the SPM by raising the temperature in a quartz tank. For this reason, the amount of use of chemicals is extremely large, and the amount of waste liquid of the processing solution after use is also large. In addition, since the SPM is maintained at a high temperature in the processing tank, there is a disadvantage that the burden on the processing apparatus is large and the frequency of maintenance of the apparatus must be increased. Organic solvents have the same problem.Especially in the case of organic solvents, it is easy to volatilize, and it is necessary to increase the degree of sealing of the processing equipment to prevent leakage and diffusion of organic substances around the equipment. Strict management is required for the treatment method for the waste liquid.

[0003] Instead of a processing liquid that burdens these apparatuses and waste liquid processing, ozone-dissolved water is used as a processing liquid for removing the resist. Ozone has a very high oxidizing power, and has a short natural decomposition time for waste liquid, and does not require special waste liquid treatment. Therefore, ozone is a treatment liquid that can be easily used in semiconductor production lines. FIG. 4 shows a so-called single-wafer type wet processing apparatus as an apparatus for performing a conventional resist removal method using ozone-dissolved water. Ozone-dissolved water generated by the ozone water production device 4 is discharged from the processing liquid discharge nozzle 3 while the wafer 1 having a photoresist film formed thereon is vacuum-sucked on the wafer stage 2 and the wafer 1 is rotated. Then, the photoresist on the wafer surface is removed by supplying it onto the wafer 1. The ozone-dissolved water producing apparatus 4 may be a commercially available apparatus, and details thereof are omitted here.

[0004]

However, the above-described conventional method of removing the resist using ozone-dissolved water has the following problems. Ozone dissolved water is DIW (De-Ionized)
Water (hereinafter referred to as DIW) is produced by dissolving ozone gas in a dissolving module. FIG. 5 shows the relationship between the DIW temperature and the concentration of dissolved ozone. 150p when DIW liquid temperature is 5 ℃
While ozone of about pm is dissolved, the ozone dissolved concentration at 25 ° C. is 100 ppm, and it can be seen that the ozone dissolved concentration further decreases as the temperature increases. As described above, the concentration of dissolved ozone in DIW is inversely proportional to the DIW temperature, and the concentration of ozone that can be dissolved in DIW decreases as the DIW temperature increases. The etching rate of the resist by the ozone-dissolved water is proportional to the ozone-dissolved concentration. The etching rate of the resist by the ozone-dissolved water is also proportional to the liquid temperature of the ozone-dissolved water. Therefore, ideally, it is desirable that the ozone concentration in the ozone-dissolved water be high and the liquid temperature of the ozone-dissolved water be high. However, as described above, since the liquid temperature of ozone and the concentration of dissolved ozone are in an inverse relationship, even if high-concentration ozone-dissolved water is produced at a low liquid temperature, the liquid temperature is raised thereafter. At this point, the ozone in the ozone-dissolved water is decomposed and becomes low-concentration ozone-dissolved water when supplied onto the resist.

[0005] As described above, in the conventional method, the resist cannot be removed with ozone-dissolved water having a high concentration and a high liquid temperature, and the etching rate cannot be increased so much. Could not shorten.

Accordingly, it is an object of the present invention to solve the above-mentioned problems of the prior art and to provide a method for removing a resist with ozone-dissolved water in a short time.

[0007]

According to the present invention, there is provided a method for removing a resist, comprising: forming a resist on a resist film formed on a semiconductor wafer;
The resist film is removed by supplying ozone-dissolved water and an ozone decomposition catalyst solution.

As described above, by supplying the ozone decomposition catalyst solution to the resist film in addition to the ozone dissolved water, even when the ozone dissolved water is at a low temperature (for example, normal temperature), the etching rate is increased (twice the conventional technology). Above).

[0009] In addition to the conventional removal of resist using only ozone-dissolved water, that is, the removal of resist by oxidizing the resist (organic substance), an ozone-decomposing catalyst such as aqueous ammonia or hydrogen peroxide is added to ozone-dissolved water. Ozone is decomposed to generate OH radicals, and the resist film (organic film) undergoes several stages of decomposition reaction to form carbon dioxide gas and water by a radical chain reaction using the OH radicals as a reaction initiator. It is considered that resist removal due to decomposition is added.

In the present invention, it is preferable that the ozone-dissolved water and the ozone decomposition catalyst liquid are separately supplied onto the resist film and mixed on the resist film.

It is preferable to supply the ozone decomposition catalyst liquid onto the resist film in advance, and then supply ozone-dissolved water onto the resist film.

While supplying the ozone-dissolved water onto the resist film, it is preferable that the ozone decomposition catalyst liquid is also continuously supplied onto the resist film.

[0013]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a schematic diagram of a resist removing apparatus according to an embodiment of the present invention. The resist removal apparatus of the present embodiment is a so-called single-wafer processing apparatus that processes wafers one by one.

The resist removing apparatus includes a rotatable wafer stage 2 in a cup 5, and the stage 2 has a function of vacuum-sucking the wafer 1. The apparatus further includes two processing liquid discharge nozzles 3 and 4 whose tips are located above the wafer stage 2, and the ozone-dissolved water generated by the ozone-dissolved water producing device 6 is used for the processing liquid discharge nozzle 3.
Thus, the ozone decomposition catalyst liquid filled in the tank 7 can be discharged from the processing liquid discharge nozzle 4 onto the wafer.

Hereinafter, a method of removing a photoresist on a semiconductor wafer according to a first embodiment of the present invention using the resist removing apparatus shown in FIG. 1 will be described.

The first embodiment is an example in which ammonia water is used as the ozone decomposition catalyst liquid. The tank 7 shown in FIG.
Ammonia water is filled.

First, a wafer 1 having a resist film formed on the upper surface thereof is vacuum-adsorbed on the wafer stage 2, and the wafer stage 2 is rotated. In this state, by opening the valves 10 and 12 and operating the pump 18,
The diluted ammonia water is discharged from the processing liquid discharge nozzle 4 and supplied onto the wafer 1 having a resist film formed on the surface.
The ammonia concentration in the diluted ammonia water may be 1000 ppm or less. Here, the adjustment of the ammonia concentration in the diluted ammonia water is performed by adjusting the valves 10 and 12 attached to the ammonia water supply pipe 9 and the DIW supply pipe 11 by the flow rate controller 8.

After the diluted ammonia water is discharged onto the wafer 1 at a flow rate of 1 L / min for 1 second or more, the valve 17 provided in the ozone-dissolved water supply pipe 16 is opened to open the ozone-dissolved water producing apparatus. The ozone-dissolved water generated in 6 is discharged onto the wafer 1 from the processing liquid discharge nozzle 3. At this time, the discharge flow rate of the ozone dissolved water may be about 1 L / min. The discharge of the diluted ammonia water is continued even during the discharge of the ozone solution.

Here, it is possible to simultaneously supply the ozone decomposition catalyst solution and the ozone-dissolved water onto the wafer 1, but the ozone decomposition catalyst solution is discharged onto the wafer 1 in advance as described above, By discharging ozone-dissolved water onto the wafer surface while the entire surface of the wafer 1 is covered with the ozone decomposition catalyst solution, ozone can be instantaneously decomposed on the wafer surface, further shortening the etching time. It is possible to do.

The processing time is as follows. When a resist having a film thickness of 1 μm is formed on the wafer 1, the etching rate of the resist when the ozone concentration of the ozone-dissolved water is 100 ppm in the presence of diluted ammonia water is 6000 Å / min. Therefore, the length is 2 min. 30 sec. In consideration of the over-etching time.

When the etching of the resist is completed, the valves 10, 12, and 17 are closed to stop the discharge of the ozone-dissolved water and the diluted ammonia water. Then, DIW
The valve 15 attached to the supply pipe 14 is opened, DIW is discharged from the processing liquid discharge nozzle 3 onto the wafer 1, and the wafer 1 is rinsed. Rinse time by DIW is 2min.
The degree is good.

After the rinsing process of the wafer 1, the drying process of the wafer 1 is performed by rotating the stage 2 at 1000 rpm. When the drying of the wafer 1 is completed,
A series of resist removing operations is completed.

According to the first embodiment, when the resist formed on the wafer surface is removed with ozone-dissolved water, ammonia water serving as an ozone-dissolving catalyst is supplied to the wafer surface in advance. In order to supply the ozone dissolving catalyst after forming a liquid film of diluted ammonia water on it,
The ozone concentration in the ozone-dissolved water can be maintained at a high level of about 100 ppm just before it is discharged onto the wafer. The chemical reaction with the resist is promoted, the etching rate of the resist film is increased, and the time for removing the resist film can be shortened.

FIG. 2 is a graph showing the etching rate of the resist by the conventional method (a method using only ozone-dissolved water) and the resist removal method of the first embodiment of the present invention. Is supplied on the resist film at room temperature. Compared with the etching rate when the ozone concentration in the ozone-dissolved water is 100 ppm, the etching rate of the resist film in the conventional method is about 3000 Å / min. In the case of the first embodiment, about 6000 mm / m
In. and an etching rate twice as high as the conventional one are obtained.
That is, according to the method for removing a resist film according to the first embodiment of the present invention, the processing can be completed in half the time of the related art.

Next, a method of removing a photoresist from a semiconductor wafer according to a second embodiment of the present invention will be described.

In the second embodiment, an example is shown in which aqueous hydrogen peroxide is used as the ozone decomposition catalyst liquid. As the resist removing apparatus, the apparatus shown in FIG. 1 is used as in the first embodiment.

The tank 7 in FIG. 1 is filled with a hydrogen peroxide solution as an ozone decomposition catalyst solution, and while the wafer stage 2 is rotated, the diluted hydrogen peroxide solution is discharged onto the wafer from the processing solution discharge nozzle 4. The concentration of the hydrogen peroxide solution in the diluted hydrogen peroxide solution may be 1% or less. The concentration of the hydrogen peroxide solution in the diluted hydrogen peroxide solution is adjusted by the flow controller 8 using the valve 10 attached to the hydrogen peroxide solution supply pipe 9 and the DIW.
This is performed by adjusting the valve 12 attached to the supply pipe.

After the diluted hydrogen peroxide solution is discharged onto the wafer surface at 1 L / min for 1 second or more, the discharge of ozone-dissolved water onto the wafer surface is started. The discharge flow rate of the ozone dissolved water at this time may be about 1 L / min. The discharge of the diluted hydrogen peroxide solution is continued even during the discharge of the ozone-dissolved water.
When the ozone concentration of the ozone-dissolved water is 100 ppm, the etching rate of the resist is 9000Å / min.
When a μm resist is formed on the wafer 1, the processing time is 1 min. 30 sec. in consideration of the amount of over-etching.

When the resist etching process is completed, the discharge of ozone-dissolved water and the diluted hydrogen peroxide solution is stopped, DIW is discharged from the processing liquid discharge nozzle 3 onto the wafer 1, and the wafer 1 is rinsed. . Rinse time by DIW should be about 2min. After the rinsing process of the wafer 1 is completed, the drying process of the wafer 1 is performed by rotating the stage 2 at 1000 rpm. When the drying of the wafer 1 is completed, a series of resist removing operations is completed.

In the second embodiment of the present invention, since hydrogen peroxide water having a resist (organic substance) etching action by itself is used as the ozone decomposition catalyst, ozone and ozone and the peroxide which is an ozone decomposition catalyst are used. Since the resist etching action of the hydrogen peroxide solution itself is added to the etching action by the reaction with the hydrogen water, the resist etching rate of the entire process is increased, and as a result, the resist stripping processing time is further shortened as compared with the first embodiment. It becomes possible.

FIG. 3 is a graph showing the etching rates of the resist according to the conventional example, the first embodiment of the present invention, and the second embodiment of the present invention. As in FIG. 2, each shows a case where ozone-dissolved water at room temperature is used. When comparing the ozone concentration in the ozone-dissolved water at 100 ppm, the conventional example is 3000 で は / min., And the first embodiment of the present invention is 6000Å / min.
In contrast, in the second embodiment of the present invention, about 9000Å / m
in. etching rate. As described above, according to the second embodiment, the processing time for removing the resist can be reduced to two thirds of the first embodiment, that is, one third of the conventional technique.

Under the resist, a film having low resistance to etching by ammonia water, such as a film mainly containing Al and a film mainly containing Ti, Cu, etc., mainly used as wiring in a semiconductor device, is formed. When removing the resist from a damaged wafer, it becomes difficult to use diluted ammonia water as the ozone decomposition catalyst solution. In contrast, the second embodiment of the present invention
In the embodiment of the present invention, since the hydrogen peroxide solution, which is a chemical contained in the conventionally used sulfuric acid-hydrogen peroxide solution mixture, is used as the ozone decomposition catalyst solution, the etching resistance with ammonia water as described above is used. Can be processed without any problem even on a wafer on which a film having a low level is formed.

The embodiments of the present invention have been described above.
It is apparent that the present invention is not limited to the above-described embodiment, but can be appropriately modified within the technical idea of the present invention.

For example, the ozone concentration in ozone-dissolved water, the temperature of ozone-dissolved water, the flow rate of ozone-dissolved water, the concentration, flow rate, and treatment time of the ozone decomposition catalyst solution (aqueous ammonia and hydrogen peroxide) are limited to those in the above embodiment. Instead, it can be appropriately changed according to the semiconductor device manufacturing capacity of the semiconductor device manufacturing line to which the processing method of the present invention is applied.

As the ozone decomposition catalyst solution, not only ammonia water and hydrogen peroxide solution, but also an alkaline chemical solution can be used as long as it does not itself become a pollution source in the semiconductor manufacturing process.

In the first and second embodiments, the ozone-dissolved water and the ozone decomposition catalyst solution are mixed on the wafer 1. However, instead of this method, before discharging onto the wafer, The ozone-dissolved water and the ozone decomposition catalyst solution may be mixed in advance. However, if both liquids are mixed before ejection, the radicals generated by the ozone-dissolved water and the ozone component catalyst liquid generally have a very short life,
When discharged to the resist, the effect of improving the etching rate of the resist is small because most of the radicals as reaction products have disappeared. Therefore, it is most preferable to mix on the wafer as in the above embodiment.

In the above embodiment, the discharge of the ozone decomposition catalyst liquid is continued even after the start of the discharge of the ozone-dissolved water, and the discharge of both liquids is stopped simultaneously. However, the discharge depends on the thickness of the resist film to be removed. Then, the discharge of the ozone decomposition catalyst liquid may be stopped at the time when the discharge of the ozone-dissolved water is started, or after the discharge is started for a while and before the discharge of the ozone-dissolved water is stopped. In this case as well, although the effect is inferior to that of the above embodiment, it is possible to shorten the etching time as compared with the prior art.

As described above, according to the present invention, in the method of removing resist using ozone-dissolved water, it is considered that the action of OH radicals generated by the decomposition of ozone by adding an ozone decomposition catalyst solution. By the decomposition reaction of the resist, an effect is obtained that the etching rate can be increased without increasing the temperature of the ozone-dissolved water.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of a resist removing apparatus according to an embodiment of the present invention.

FIG. 2 is a graph showing the etching rates of the processing according to the first embodiment of the present invention and the processing according to the conventional method.

FIG. 3 is a graph showing the etching rates of the processing according to the first embodiment, the processing according to the second embodiment, and the processing according to the conventional method of the present invention.

FIG. 4 is a schematic view of a conventional resist removing apparatus.

Fig. 5 Relationship between DIW concentration and ozone dissolved concentration

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Wafer 2 Wafer stage 3, 4 Processing liquid discharge nozzle 5 Cup 6 Ozone dissolved water production apparatus 7 Tank 8 Flow controller 9 Ozone decomposition catalyst liquid supply pipe 10, 12, 15, 17 Valve 11, 14 DIW supply pipe 18 Pump

Claims (10)

[Claims] 1. A method for removing a resist film by supplying ozone-dissolved water and an ozone decomposition catalyst solution onto a resist film formed on a semiconductor wafer. 2. The method according to claim 1, wherein the ozone decomposition catalyst liquid is ammonia water. 3. The method according to claim 1, wherein the ozone decomposition catalyst liquid is a hydrogen peroxide solution. 4. The method according to claim 1, wherein the ozone decomposition catalyst liquid is an alkaline solution. 5. The method according to claim 1, wherein the ozone decomposition catalyst liquid is a chemical liquid that decomposes ozone in the ozone-dissolved water to generate OH radicals. 6. The method according to claim 1, wherein the ozone-dissolved water and the ozone decomposition catalyst solution are separately supplied onto the resist film and mixed on the resist film. 7. The supply of the ozone-dissolved water and the ozone-decomposition catalyst liquid onto the resist film includes supplying the ozone-decomposition catalyst liquid onto the resist film in advance, and then applying the ozone-decomposition catalyst liquid to the resist film. 2. The method according to claim 1, wherein the resist is supplied onto the film. 8. The method according to claim 6, wherein the supply of the ozone decomposition catalyst liquid onto the resist film is continued even when the ozone decomposition catalyst liquid is supplied onto the resist film.
The resist removal method described in the above. 9. The method according to claim 1, wherein the ozone-dissolved water is supplied onto the resist film at a normal temperature. 10. The method according to claim 3, wherein a film having low etching resistance to an alkaline solution is formed under the resist film.