JPH0646630B2 - Plasma processing method - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a plasma processing method, and more particularly to a plasma processing method suitable for removing a surface damage layer of a sample generated after etching.

[Background of the Invention]

The method of transferring the pattern to the film deposited on the sample is shifting from the wet etching method to the dry etching method. In the dry etching method, when the SiO ₂ film is etched using a gas containing C, O, H, F, etc., stacking faults are formed on the surface of the underlying Si, and these stacking faults are about 200 Å. It is known that the plasma can be almost completely removed by performing an after-etching process of plasma in which CF ₄ or Cl ₂ gas is introduced up to the depth of. (J. Dielembn, F.
HM Sanders, "Plasma Etching: Selectivity and Non-Damage", Solid. State. Technology (Solid st
ate technology) Japan edition 6th issue 1984, 68th issue, P
80-84) In order to remove the surface defect layer formed by dry etching, wet treatment using a chemical solution (organic acid, inorganic acid, etc.) is also possible, but when the wet treatment is used, waste solution treatment or pure water is used. Recently, a method using CF ₄ or Cl ₂ gas has been adopted because a large amount of cost is required for manufacturing. However, when CF ₄ gas is used, there is a problem that the C component still remains on the surface of the sample after the treatment because the gas contains C, and when Cl ₂ gas is used. Had a problem that the exhaust system requires a low temperature trap function and a dedicated exhaust gas treatment device (for example, a scrubber, an adsorption tower, etc.).

Further, in the plasma processing, ions are always generated and incident on the workpiece, but there is a problem that the larger the mass number of ions, the larger the lattice defect.

[Object of the Invention]

An object of the present invention is to provide a plasma processing method capable of removing a surface damage layer of a sample without changing the configuration of the apparatus by selecting a reactive gas.

[Outline of Invention]

The present invention is characterized in that the surface damage layer of the sample generated in the step of plasma-etching a sample that reacts with a fluorine-based gas with a reactive gas, and etching removal with the plasma of a fluorine gas are performed, and the configuration of the apparatus is changed. Instead, the surface damage layer of the sample can be removed.

Example of Invention

An embodiment of the present invention will be described below with reference to FIGS. 1 and 2.

FIG. 1 shows a sample table 8a on which a sample 1 is placed and a sample table 8a.
A processing chamber 2a in which the inside of the processing chamber 2a is disposed, a plasma generation chamber 9a installed in communication with the processing chamber 2a, an exhaust member 7 for evacuating the processing chamber 2a and the plasma generation chamber 9a to a predetermined pressure, and the processing chamber. 2a and a plasma generating chamber 9a, a gas supply system 6 for supplying a reactive gas which is a processing gas, a ground electrode 5 for generating a plasma of the reactive gas in the plasma generating chamber 9a, an applying electrode 4, a high frequency power source 3 In the plasma processing apparatus including the above, the plasma generated in the plasma generating chamber 9a is transported to the processing chamber 2a to perform the plasma processing of the sample 1.

Fig. 2 shows that the unprocessed lifetime is 85 to 95 µsec.
Then, when CHF ₃ is used, a sample having a lifetime after etching of 13 to 18 μsec, in this case, a Si single crystal Si substrate is used as a reactive gas with Cl as a reactive gas.
₂ , the surface damage layer of the sample was removed using CF ₄ and F ₂ , and the sample lifetimes were compared. Here, Table 1 shows the etching conditions of each reactive gas.

When the surface damage layer after etching of CHF ₃ is treated with Cl ₂ discharge, the lifetime of the sample is restored to 58 to 66 μsec, with CF ₄ discharge to 38 to 48 μsec, and with F ₂ discharge to 60. Recovers up to ~ 70μsec.

If F ₂ gas is used to remove the surface damage layer of the sample as in the above Example 1, the recovery of the lifetime of the sample is improved.
Compared with Cl ₂ and CF ₄ , it is equal to or more than that, and it does not require a dedicated exhaust gas treatment device in the exhaust system like Cl ₂ and does not leave C component like CF ₄ .

Next, a second embodiment of the present invention will be described with reference to FIGS. 3 and 4.

FIG. 3 shows a sample table 8b on which the sample 1 is placed and a sample table 8b.
Processing chamber 2b in which the inside is disposed, a plasma generation chamber 9b communicating with the processing chamber 2b, an exhaust system 7 for evacuating the inside of the processing chamber 2b and the plasma generation chamber 9b to a predetermined pressure, the processing chamber 2b and plasma generation. It comprises a gas supply system 6 for supplying a reactive gas into the chamber 9b, a microwave source 10 for generating a plasma of the reactive gas in the plasma generating chamber 9b, and a magnet provided around the plasma generating chamber 9b. In the plasma apparatus according to the first aspect of the present invention, plasma is generated using microwaves to perform plasma processing on the sample 1.

FIG. 4 compares the same reactive gas as in FIG. 2 using the apparatus of FIG. Raw and CH
F ₃ lifetime of the sample after etching, similar to those used in Figure 2, the untreated during the 85~95μsec, CHF ₃
After etching, the etching time is 13 to 18 μsec. Table 2 shows the etching conditions for each reactive gas.

When the surface damage layer after CHF ₃ etching is subjected to Cl ₂ discharge treatment, the sample lifetime is restored to 75 to 85 μsec, CF ₄ discharge treatment is restored to 55 to 65 μsec, and F ₂ discharge treatment is restored to 80 to 90 μsec. .

Also in the apparatus of the second embodiment, if F ₂ gas is used to remove the surface damage layer of the sample, the same effect as that of the first embodiment can be obtained.

Next, a third embodiment of the present invention will be described with reference to FIGS.

FIG. 5 shows a sample table 8c, which is an electrode on which a sample is placed, a counter electrode 12 provided so as to face the sample table 8c, and a sample table 8
c and the counter electrode 12 inside, a processing chamber 2c, an exhaust system 7 for evacuating the processing chamber 2c to a predetermined pressure, and a gas supply system 6 for supplying a reactive gas into the processing chamber 2c. This is a plasma device composed of a high-frequency power source 3 for converting a reactive gas into plasma between the sample stage 8c and the counter electrode 12, and is a device generally called an anode coupling system.

FIG. 6 compares the same reactive gas as in FIG. 2 using the apparatus of FIG. Raw and CH
F ₃ lifetime of the sample after etching, similar to those used in Figure 2, the untreated during the 85~95μsec, CHF ₃
After etching, the etching time is 13 to 18 μsec. Here, Table 3 shows the etching conditions of each reactive gas.

When the surface damage layer after CHF ₃ etching was treated with Cl ₂ discharge, the lifetime of the sample was recovered to 32 to 39 μsec,
The CF ₄ discharge treatment recovers to 25 to 32 μsec, and the F ₂ discharge treatment recovers to 45 to 55 μsec.

Also in the apparatus of the third embodiment, if F ₂ gas is used to remove the surface damage layer of the sample, the same effect as that of the first embodiment can be obtained.

Next, a fourth embodiment of the present invention will be described with reference to FIGS. 7 and 8.

FIG. 7 shows a sample table 8d for holding a sample, a processing chamber 2d in which the sample table 8d is arranged, an exhaust system 7 for evacuating the processing chamber 2d to a predetermined pressure, and a reactivity in the processing chamber 2d. Plasma composed of a gas supply system 6 for supplying a gas, an earth electrode 5 provided across the processing chamber 2d for plasmaizing the reactive gas in the processing chamber 2d, an application electrode 4 and a high frequency power source 3 It is a device of a type generally called a barrel type.

FIG. 8 compares the same reactive gas as in FIG. 2 using the apparatus of FIG. Raw and CH
F ₃ lifetime of the sample after etching, similar to those used in Figure 2, the untreated during the 85~95μsec, CHF ₃
After etching, the etching time is 13 to 18 μsec. Table 4 shows the etching conditions of each reactive gas.

When the surface damage layer after CHF ₃ etching is treated with Cl ₂ discharge, the lifetime of the sample is recovered to 28 to 35 μsec,
The CF ₄ discharge treatment recovers to 22 to 27 μsec, and the F ₂ discharge treatment recovers to 25 to 32 μsec.

Also in the apparatus of the fourth embodiment, if F ₂ gas is used to remove the surface damage layer of the sample, the same effect as that of the first embodiment can be obtained.

As described above, since the surface damage layer can be removed by using F ₂ gas without using a chlorine-based gas as in these examples, the cost can be saved without remodeling the apparatus or the waste gas treatment facility. You can Further, the post-treatment with F ₂ gas is performed by the plasma transport type of the one embodiment, the microwave discharge type of the second embodiment, the anode couple type of the third embodiment, and the fourth embodiment.
It can be used for each etching apparatus of the barrel type or the like of the above embodiment and has high versatility. Further, since the mass of F ₂ gas is smaller than that of Cl ₂ gas, lattice defects generated in the sample during etching are reduced, and the effect of damage recovery is large.

In this embodiment, the sample of the single crystal Si substrate is described, but in addition to this, the same effect can be obtained for the polycrystalline Si film, the molybdenum silicide film and the tungsten silicide film as the surface damage layer can be removed by the fluorine gas. be able to.

〔The invention's effect〕

According to the present invention, by using the fluorine gas to remove the surface damage layer of the sample, it is possible to remove the surface damage layer of the sample without changing the configuration of the apparatus.

[Brief description of drawings]

FIGS. 1, 3, 5, and 7 are configuration diagrams showing an apparatus for carrying out the present invention, and FIGS. 2, 4, 6, and 8 show experimental results of the present invention. It is a graph which shows. 1 ... Sample, 2a to 2d ... Processing chamber, 3 ... High frequency power source, 6 ... Gas supply system, 7 ... Exhaust system, 9a, 9b ...
… Plasma generation chamber, 10… Microwave source

Claims (1)

[Claims] 1. A plasma processing method, characterized in that a surface damage layer of a sample generated in a step of plasma etching a sample that reacts with a fluorine-based gas with a reactive gas is removed by etching with plasma of a fluorine gas.