JPH02226722A - Treatment of organic film - Google Patents

Abstract

PURPOSE:To remove an organic film having a hardened region rapidly without leaving any residue and stably without damaging an underlying wafer by treating the organic film with plasma as required. CONSTITUTION:By treating a wafer with etching plasma containing at least hydrogen, a hardened region in an organic film which has been carbonized and hardened by bombardment of charged particles containing ions on the wafer can be removed rapidly without leaving any residue and stably without damaging the underlying wafer. This pretreatment provides conditions facilitating a chemical action and, therefore, subsequent treatments of the organic film can be performed in a desirable manner.

Description

[Detailed Description of the Invention] [Summary] Concerning a method for processing an organic film, the organic film having a hardened region that is carbonized and hardened by being bombarded by charged particles containing ions can be quickly, without any residue, and applied to an underlying wafer, etc. The purpose of the present invention is to provide a method for treating organic films that can be stably removed without causing damage. In a method for treating an organic film in which the film is treated with a chemical reaction, 1.
The method is configured to include a step of treating the hardened region of the organic film with plasma containing at least hydrogen prior to the treatment involving the chemical reaction to make it more likely to cause a chemical reaction.

[Industrial application field]

The present invention relates to a method for processing an organic film, which has a hardened region that is carbonized and hardened by the impact of charged particles containing ions, and is used, for example, as an ion implantation mask or patterning mask in a semiconductor device manufacturing method. The present invention can be applied to a method for treating organic films such as resists, and in particular, it relates to a method for treating organic films that can quickly remove the organic film in which the hardened region is present without leaving any residue.

When an organic film is bombarded by charged particles containing ions, it carbonizes and hardens to form a hardened region.
yama etc, JJ1ctroche+m, soc
Vol, 125°No, 8＾gust 1978
PP, 1293-1298 and is known. Since the hardened region has a depth that allows ions to reach, it is formed particularly close to the surface area of the organic film that is bombarded by charged particles containing ions, and hardened regions are formed in areas where charged particles containing ions do not reach. is not formed. It is known that an organic film having such a carbonized and hardened region cannot be removed only by a general wet chemical treatment, and can be removed by irradiating oxygen plasma.
This treatment method using oxygen plasma produces a large amount of residue such as oxides of non-volatile ionic species. Therefore, this residue is often removed by etching the underlying layer (for example, a wafer made of Si, a wiring layer made of A1, etc.) by lift-off. For example, in the manufacturing process of semiconductor devices, this residue becomes particles and is one of the factors that lowers the yield. In addition, an organic film having a hardened region such as - has high resistance to oxygen-containing plasma, and the processing speed is also reduced. Furthermore, in view of recent miniaturization of semiconductor devices, it is not preferable to remove the resist in plasma until the underlying layer is exposed because damage will occur.

Therefore, there is a need for a removal method that can quickly remove an organic film having a hardened region without leaving any residue and with minimal damage.

[Prior Art] A method for treating an organic film that can remove without any residue an organic film having a hardened region that is carbonized and hardened by the impact of charged particles containing ions, such as a resist used as a mask for ion implantation, is as follows. A method is known in which all of the gas is removed by plasma treatment 1 using a gas containing hydrogen but not containing oxygen.

[Problems to be Solved by the Invention] In this method of treating an organic film using plasma treatment that contains hydrogen but does not contain oxygen, all hardened areas can be completely removed without producing oxide residues as in oxygen plasma treatment. However, even when processing is performed using only hydrogen plasma, the rate of etching (also called ashing) of the organic film is very slow (for example, 300 cc of H2 gas, 0 pressure). .5 Torr,
The etching rate for 0FPR-800 (trade name, manufactured by Tokyo Ohka Co., Ltd.), an organic film without a hardened area called a positive photoresist, using RIE at RF 13.56 MHz and power 300 W is approximately 700 people/min. The etching rate for organic films with carbonized and hardened areas is less than 500 people/min. ),
The problem was that it was not practical. Furthermore, there is a problem in that the underlying wafer and the like are etched, resulting in damage to the wafer and the like.

By the way, as a means to solve the above-mentioned problem of slow etching speed, an organic film processing method using HtO plasma has been proposed, and it is considered to be an effective method that produces relatively no residue and has a faster etching speed than H2 plasma. However, this method had the problem of producing a peculiar deposit-like residue.

Specifically, for example, when removing an organic film having localized hardened regions on a Si wafer, a unique deposit-like residue is generated where the organic film was. The residues here are Si, C, and O.

It is presumed that H, etc. were mixed in. therefore,
When such a residue is generated, a new removal step is required to remove the residue.

Therefore, the present invention provides a process for removing an organic film having a hardened region that is carbonized and hardened by being bombarded by charged particles containing ions, quickly and without leaving any residue, and stably without damaging the underlying wafer, etc. The purpose of the present invention is to provide a method for treating organic films that can be used to treat organic films.

[Means to solve the problem]

In order to achieve the above objectives, the method for treating an organic film according to the present invention has the following features:
In a method for treating an organic film in which a treatment involving a chemical reaction is performed on an organic film having a hardened region that is carbonized and hardened by being bombarded by charged particles containing at least ions, the organic film is treated with a chemical reaction. The method includes a step of treating the hardened region of the film with plasma containing at least hydrogen to modify it so that chemical reactions occur more easily.

(Function) The present invention provides a method for treating an organic film having a hardened region that is carbonized and hardened by the impact of charged particles containing at least ions. Prior to the treatment, the hardened region of the organic film is treated with plasma containing at least hydrogen to modify it so that a chemical reaction occurs more easily.

Therefore, since the hardened region of the organic film is modified so that it can be removed by chemical treatment, the organic film having the hardened region can be removed by chemical treatment without any residue.

Since it can be performed using, for example, downstream chemical treatment, it can be removed more quickly than the conventional method of removing only H2 plasma treatment or H, O plasma treatment. In addition, because it is possible to perform downstream chemical processing with a high selectivity on the underlying wafer, etc., H2
This enables stable removal without damaging the underlying wafer, etc., compared to the method of removing using only plasma processing.

(Example) Hereinafter, the present invention will be explained based on the drawings.

FIGS. 1 to 3 are diagrams for explaining one embodiment of the organic film processing method according to the present invention, and FIG. 1 is a schematic diagram showing a removal device (here, R1E device) of one embodiment. , FIG. 2 is a diagram showing details of the wafer holding and cooling mechanism of the removal apparatus of one embodiment, and FIGS. 3(a) to (C) are diagrams explaining the effects of one embodiment.

In these teeth, l is a wafer made of Si, for example;
2 is an organic film used for example in resist, 3 is an inlet for introducing a gas for etching, etc., 4 is quartz, 5 is a counter electrode, 6 is an inlet for introducing cooling water (cooling gas), 7
is an exhaust port for introducing cooling water (cooling gas), 8 is a DC power source, 9 is an RF power source, 10a and lob are insulators, 11 is an exhaust port for vacuum exhaust, 12 is an electrostatic chuck electrode, and 13 is a cathode. 14 is an inlet for introducing cooling gas, 15 is an exhaust port for evacuating the cooling gas, 16 is an inlet for introducing cooling water, and 17 is an outlet for discharging waste water.

First, as shown in Table 1, using an organic film that does not have a hardened region that has not been subjected to the impact of charged particles containing ions, plasma treatment with H2 gas, plasma treatment with H, O gas, and plasma treatment with 02 gas are performed. Each plasma treatment was performed and the etching rate (in/min) was investigated.

Table 1 Specifically, each etching rate (person/min) here is for the commercially available positive photoresist 0FPR-8 as the organic film 2.
00 (trade name, manufactured by Tokyo Ohka Co., Ltd.; the base polymer is novolac resin), the organic film 2 is coated on a wafer 1 with a diameter of 6 inches, for example, to a thickness of about 1.1 am, and then heated to a thickness of 120' with a hot plate. C: Etching rate when a sample baked for 2 minutes was plasma etched using 02 gas, H, O gas, and N2 gas, respectively. As the removal device for the organic film 2, a commonly used RIE device as shown in FIGS. 1 and 2 is used, and the etching conditions include a flow rate of each gas of 300 cc for 7 minutes, and a pressure of 0.5 cc, for example. 5 Torr, 0. ITorr, RF power is e.g. 300 W, 500 W, RF is e.g. 1
3.56 MHz, and the stage temperature is, for example, about 6°C.

From Table 1, the etching speed increases in the order of H8 plasma treatment, H,O plasma treatment, and 08 plasma treatment.In H3 plasma treatment, the etching speed is extremely slow to remove organic films that do not have hardened regions. It turns out that. In addition, here, H! plasma treatment, H,O
As mentioned above, if an organic film having a hardened region is removed only by plasma treatment or Oz plasma treatment, problems such as etching rate and residue will occur.

Next, as shown in Table 2, using an organic film having a hardened region that was carbonized and hardened by the impact of charged particles containing ions, we applied H, which had a higher etching rate than the H2 plasma treatment in Table 1. Using O plasma treatment, after this H,O plasma treatment, downstream treatment was performed as a chemical treatment to examine the amount of film reduction and the presence or absence of residue.

Table 2 Specifically, using 11□0 gas, ions of, for example, As as an impurity were added to an organic film similar to that described in Table 1 at a dose of, for example, l×1016 pieces/c4, and an energy of, for example, 70 Kev. After injecting and performing H20 plasma treatment, downstream was performed by converting a mixed gas of 02 gas and 10% N2 gas into plasma as chemical treatment. O1Δ, × indicates the amount of residue left after downstream processing, ○ indicates that the cured area has been removed without any residue, Δ indicates that the cured area has some residue, and × indicates that the cured area is partially removed. It shows a state in which there are countless residues of hardened areas on one surface. Specifically, the conditions for downstream processing here are, for example, 0□gas 10 N!
Gas (10%) flow rate is, for example, 1ffi/min, pressure is, for example, I Torr, frequency is, for example, 2.45 GHz, power is, for example, 1.5 KW, and stage temperature is, for example, 15
0''C. The amount of film loss (in) removed during the H,O plasma treatment is also shown.

From Table 2, it can be seen that the hardened region of the organic film 2 cannot be removed by processing mainly based on chemical reactions such as downstream processing, so × and Δ indicate that the hardened region is not sufficiently removed during H, O plasma treatment, or that the hardened region is hardened. It can be seen that the region has not been modified for downstream removal.

Since the downstream etching rate is approximately 500 in/min here, if the hardened area is completely removed or modified so that it can be removed downstream, the thickness of the organic film 2 will be Since it is 1.1 μm, 3 minutes of downstream processing should be enough to remove it. On the other hand, after ion implantation
In other words, an organic film without a hardened region that has not been bombarded by charged particles containing ions can be removed in about 2 minutes and 10 seconds. In addition, the amount of film loss per minute in Table 2 (
The reason why the etching rate (etching rate) is lower than the etching rate in Table 1 is because the etching rate in the hardened area is slower than in the unhardened area.

Furthermore, from Table 2, it can be seen that in the system of H, O plasma treatment + downstream treatment, a residue in the hardened region is generated unless about 2000 or more particles are removed by I]20 plasma treatment. Therefore, considering that the thickness of the hardened region is about 2000 mm, it can be seen that in the case of H, O plasma treatment, it cannot be expected to modify the hardened region so that it can be removed downstream. That is, unless the entire hardened area is removed by H, O plasma treatment, a residue of the hardened area will remain.

In addition, since H, O plasma treatment is performed here,
As mentioned above, even if no residue is produced in the hardened region, the problem of the peculiar deposit-like residue cannot be solved.

However, H2 plasma treatment (0.5 Torr 30
After 0W 300cc 1 minute), downstream processing similar to that described in Table 2 did not result in hardened area residue or the characteristic deposit-like residue that occurs with H,O plasma. Since the amount of film reduction of the organic film in 1 minute of this H2 plasma treatment was about 400, the hardened area was naturally 2000, so the hardened area remained. Nevertheless, the reason why the above-mentioned residue did not occur when downstream processing was performed indicates that the hardened area was modified by H2 plasma treatment so that it could be removed by downstream processing. Further, since downstream chemical processing is used, it is possible to remove the particles more quickly than the conventional method, which uses only H, plasma processing, or H, O plasma processing. In addition, because it is possible to perform downstream chemical processing with a high selectivity on the underlying wafer, etc., it causes less damage to the underlying wafer, etc. than the conventional method, which removes only with H2 plasma treatment. can be stably removed without

Here, the fact that the organic film having the hardened region could be removed by the chemical treatment called downstream treatment after the Hz plasma treatment can be chemically estimated as follows.

When ions of 1X10 or more of phosphorus are implanted as an impurity into the novolac resin shown in FIG. 3(a) constituting the organic film, for example, the resin is carbonized and hardened to form a structure as shown in FIG. 3(b). The benzene rings shown in FIG. 3(b) have a structure in which they are mutually cross-linked with phosphorus, and are extremely difficult to chemically decompose, requiring plasma treatment to decompose them. However, as described above, in the conventional 0□ plasma treatment, phosphorus is oxidized to form a nonvolatile oxide and become a residue. The conventional method was to remove the organic film having the hardened region at a time only by H, plasma treatment, and H, O plasma treatment.

However, in the above embodiment of the present invention, unlike the conventional method, the hardened region of the organic film is modified so that it can be removed by downstream chemical treatment, as shown in FIG. 3(b). Fundamentally different, H2
It is thought that the plasma treatment reformed the structure into a hydrogenated structure again, as shown in FIG. 3(C). That is, it is thought that the benzene rings and the like in the hardened region are destroyed and hydrogenated to form a form similar to aliphatic metals, and the dopant is also hydrogenated and becomes volatile.

Furthermore, HzO plasma treatment + downstream treatment (a
), H, O plasma treatment only (b), I-(2 plasma treatment + downstream treatment (C), and H2 plasma treatment only (d)).

Using, for example, OF RR-800 (trade name, manufactured by Tokyo Ohka Co., Ltd.) as an organic film, an organic film pattern with a film thickness of, for example, 1 μm is formed on a Si wafer using a photolithography process. , then the dose is set to, for example, l
An organic film having a hardened region was formed by ion implantation with Xl0''/c4 and an energy of, for example, 70 Keν. After that, H, O plasma treatment + downstream treatment (a), H, O plasma treatment only (b) ), Hz plasma processor downstream processing (C) and H
.

The organic film having the hardened region was removed by performing plasma treatment (d). The conditions were H, O plasma treatment for 1 minute (300cc 7 minutes, 300W% 0.
5 Torr) + downstream treatment (a), H20 plasma treatment for 5 minutes only (b), Hz plasma treatment for 1 minute (3
00cc 7 minutes, 300 W, 0.5 Torr) + downstream treatment (C), and HzO plasma treatment 1
Perform each of the above four processes for only 8 minutes (d),
The surface of the wafer after the treatment was observed using a SEM or the like. In cases (a) and (b) where H20 plasma treatment was used, a deposit-like residue was generated where the organic film was, whereas t
Those using +z plasma treatment (C) and (d) were clean with no residue. However, in the case of (d) with only H2 plasma treatment, even the wafer was removed.

In the above example, the case where downstream treatment is used as the chemical treatment after the 11□ plasma treatment was explained, but the present invention is not limited to this, and the present invention is not limited to this, and it is possible to use an organic film having a modified hardened region. Any chemical treatment that can remove it may be used, such as ozone ashing, wet treatment, or the like.

The above embodiments are pure ir as a method of modifying the organic film so that the hardened region can be removed by chemical treatment.

Although the case of performing H plasma processing using gas (100%) has been described, the present invention is not limited to this. It is sufficient that the number ratio of oxygen atoms to hydrogen atoms in the source gas is smaller than 1/2.

In addition, the plasma containing hydrogen may be hydrogen alone, but since hydrogen gas is a highly explosive gas, it may be ionized gas diluted with a rare gas such as He. good.

Although the present invention has been described above in detail with respect to the case where an organic film such as a resist is removed by performing a process that involves a chemical reaction such as a downstream process containing oxygen, the application of the present invention is not limited to this. For example, this can also be used when subjecting an organic film to boiling treatment.

Specifically, for example, when ions are implanted into an organic film such as a resist layer to form a conductive organic film, the vicinity of the surface is further treated by downstream treatment containing fluorine. Boiling has the advantage of improving the resistance to oxygen and ozone mentioned above, but the part that has been carbonized and hardened by ion implantation has the disadvantage of being difficult to chemically react, making it difficult for the boiling treatment to progress. .

However, prior to this boiling treatment,
When plasma treatment containing hydrogen is performed under the same conditions as described in the above embodiment, boiling treatment can be easily performed by downstream treatment containing fluorine or the like.

[Effects of the Invention] According to the present invention, an organic film having a hardened region that is carbonized and hardened by being bombarded by charged particles containing ions can be formed quickly without any residue and stably without damaging the underlying wafer etc. This has the effect that it is possible to perform processing such as removal.

[Brief explanation of the drawing]

FIGS. 1 to 3 are diagrams explaining an embodiment of the organic film treatment method according to the present invention, FIG. 1 is a schematic diagram showing a removal device of one embodiment, and FIG. 2 is a diagram of one embodiment. FIG. 3 is a diagram illustrating the effects of one embodiment. 1...Wafer, 2...Organic film. Figure Figure

Claims (7)

[Claims] (1) An organic film processing method in which a treatment involving a chemical reaction is performed on an organic film having a hardened region that is carbonized and hardened by being bombarded by charged particles containing at least ions, the treatment involving the chemical reaction as described above. A method for treating an organic film, comprising the step of first treating the hardened region of the organic film with plasma containing at least hydrogen to modify it so that a chemical reaction occurs more easily. (2) Claim 1 characterized in that the number ratio of oxygen atoms in the source gas for generating the plasma containing hydrogen when performing plasma treatment containing at least hydrogen is smaller than 1/2 with respect to hydrogen atoms. The method for treating the organic film described above. (3) The method for treating an organic film according to claim 1 or 2, wherein the treatment involving a chemical reaction is treatment by downstream of plasma containing oxygen or fluorine. (4) The method for treating an organic film according to any one of claims 1 to 3, characterized in that the bombardment of charged particles containing ions is brought about by ion implantation. (5) The method for treating an organic film according to claim 4, wherein the amount of ions is 1×10^1^4/cm^2 or more. (6) The method for treating an organic film according to claim 1, wherein the plasma containing hydrogen is ionized hydrogen or a gas obtained by diluting hydrogen with a rare gas. (7) The method for treating an organic film according to claim 6, wherein the gas for diluting hydrogen is helium.