JPS639935A - Dry etching device - Google Patents

Abstract

PURPOSE:To enable dry etching, through which damage is hardly generated, by controlling a reaching to a substrate to be etched of charged particles by an ion collector. CONSTITUTION:A reaching inhibiting means for inhibiting a reaching to a substrate to be etched of charged particles generated together with metastable excitation species by a metastable excitation-seed generating section 6 is provided. An ion collector 7 is used as the reaching inhibiting means, and the connecting section of a reaction chamber 1 and the metastable excitation-species generating section 6 is fitted. An silicon substrate 2 is employed as the substrate to be etched, and nitrogen gas, argon gas or xenon gas is used as a gas for generating the metastable excitation species When conducting microwave discharge, partial charged particles hold charges even at a stage when they reach to the connecting section of the reaction chamber 1 and an introducing pipe 31, but the greater part of such charged particles are removed by the ion collector 7. Accordingly, the damage of the surface of the substrate to be etched 2 by charged particles can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a dry etching apparatus used in the process of manufacturing semiconductor integrated circuits and the like. .

[Conventional technology]

Dry etching equipment used in the manufacturing process of semiconductor integrated circuits, etc. includes plasma etching equipment, reactive sputter etching equipment, etc., and these are currently widely used.

In these etching devices, a process gas containing a halogen element is discharged under reduced pressure to generate reactive species such as radicals and ions, and these reactive species react with the surface of the substrate to be etched. Etching the substrate.

This is because such dry etching equipment is superior to solution etching equipment in terms of processing accuracy.

Under the current situation where processing dimensions are becoming finer and it is necessary to process single-level patterns, this technology is becoming more and more important. However, in plasma etching equipment and reactive sputter etching equipment, the substrate to be etched is placed inside a discharge vessel, so the substrate to be etched is easily damaged by charged particles, and the resist may deteriorate due to heat radiation from the plasma. There is a problem.

A new dry etching apparatus (Japanese Unexamined Patent Publication No. 61-22628) has been proposed by the present inventors to solve these problems. This dry etching apparatus includes a reaction chamber for accommodating a substrate to be etched, an exhaust means for evacuating the reaction chamber, a means for generating metastable excited species for generating metastable excited species, and a means for generating metastable excited species for evacuation of the reaction chamber. and a means for introducing a process gas containing a halogen element into the reaction chamber, and the substrate to be etched is etched with the process gas activated by a deexcitation reaction of metastable excited species.

In such an etching apparatus, since no discharge is performed in the reaction chamber that houses the substrate to be etched, problems such as damage to the substrate to be etched due to charged particles and deterioration of the resist due to heat radiation from the plasma are greatly reduced. be able to.

[Problem that the invention seeks to solve]

However, in this dry etching device,
Some of the ions generated together with the metastable excited species by the metastable excited species generation means flow into the reaction chamber.

For example, when a rare gas is used as a gas for generating metastable excited species, He", Ar", Ne", Kr+
etc. flow into the reaction chamber. This means that when, for example, Ha gas is used as the gas for generating metastable excited species, if CO□ gas is separately introduced into the reaction chamber, G O" (A - X)
This is clear from the fact that the luminescence of WA is observed. Furthermore, even when nitrogen gas is used as a gas for generating metastable excited species, N , + (x
12g4'') is produced and flows into the reaction chamber.

In this way, when charged particles such as ions flow into the reaction chamber, the surface of the substrate to be etched is damaged by the charged particles.

The present invention has been made to solve the above-mentioned problems, and it is an object of the present invention to provide a dry etching apparatus in which the surface of a substrate to be etched is not damaged by charged particles.

[Means for solving problems]

To achieve this objective, in this invention.

a reaction chamber for accommodating a substrate to be etched, an exhaust means for evacuating the reaction chamber, a metastable excited species generation means for generating a metastable excited species, and a metastable excitation for introducing the metastable excited species into the reaction chamber. With different means.

In a dry etching apparatus having a process gas introducing means for introducing a process gas containing a halogen element into the reaction chamber, charged particles generated together with the metastable excited species in the metastable excited species generating means reach the substrate to be etched. A reach suppression means is provided to suppress this.

[Effect]

In this dry etching apparatus, it is possible to suppress the charged particles from reaching the substrate to be etched by the arrival suppressing means, and it is possible to prevent the surface of the substrate to be etched from being damaged by the charged particles.

〔Example〕

FIG. 1 is a diagram showing a dry etching apparatus according to the present invention. In FIG. 0, 1 is a reaction chamber, 2 is a silicon substrate housed in the reaction chamber 1, 3 is a nitrogen gas storage section, and 31 is a storage section 3. and the reaction chamber 1, 4 is an introduction pipe 31
5 is a mass flow controller provided in the introduction pipe 31, and 6 is a metastable excited species generator provided in the introduction pipe 31.

The metastable excited species generating section 6 generates metastable excited species using microwave discharge of 2.45 GHz, and the gas outflow side end face of the metastable excited species generating section 6 and the inlet pipe 31 of the reaction chamber 1 are connected to each other. The distance between the connecting portion and the connecting portion is 20 cm or more. 7 is an ion collector provided at the connection between the reaction chamber 1 and the introduction tube 31; 8 is a storage section for a process gas containing a halogen element; 32 is an introduction tube that connects the storage section 8 and the reaction chamber 1;
9 is a valve provided in the introduction pipe 32, 10 is a mass flow controller provided in the introduction pipe 32, and 11.12 is a gas ejection port of the introduction pipe 32.

Gas outlets 11 , 12 open into the reaction chamber 1 .

13 is an exhaust device for exhausting the inside of the reaction chamber 1. and,
A connection part between the reaction chamber 1 and the introduction pipe 31 is provided on the most upstream side, a gas outlet 11.12 is provided on the downstream side, a silicon substrate 2 is provided on the downstream side, and a reaction chamber is provided on the downstream side. 1 and the exhaust bag @13 are provided.

In this etching apparatus, after the inside of the reaction chamber 1 is evacuated by the exhaust device 13, the flow rate from the storage section 3 is 5.
When nitrogen gas of 11IQ/11in is led to the metastable excited species generation section 6 through the valve 4 and the mass flow controller 5, and microwave discharge is performed in the metastable excited species generation section 6 with a microwave output of 200W, metastable excited species are generated. In part 6, many chemical species such as ions, electrons, radicals, and metastable excited molecules are generated. These ions, electrons, radicals, etc. disappear due to recombination reactions as they move away from the discharge part.

Some of the charged particles retain their charge even when they reach the connection between the reaction chamber 1 and the introduction pipe 31. However, since the ion collector 7 is provided at the connection between the reaction chamber 1 and the introduction tube 31, most of these charged particles are removed by the ion collector 7, and neutral metastable excited molecules are left in the reaction chamber. 1. Here, nitrogen molecules exist in various excited states, but in particular, the metastable excited state N2'' (A3Σu
+) stays at that level for a long time (lifetime is about 2 seconds). Therefore, the metastable excited species N, *(A2Σu+)
is at that level even when it flows into the reaction chamber 1. On the other hand, the process gas flowing out from the storage section 8 passes through a valve 9 and a mass flow controller 10, and then branches into two directions.
Gas flows into the reaction chamber 1 through the gas outlets 11.12. Therefore, in one reaction chamber 1, the metastable excited species N,'(A'Σu+
) and process gas react, metastable excited species N, *
(A 3Σu+) activates the process gas, and as a result, the silicon substrate 2 is etched. Then, the reaction product, unreacted nitrogen gas, and unreacted process gas are exhausted by the exhaust device 13.

In this way, most of the charged particles are removed by the ion collector 7 and neutral metastable excited species flow into the reaction chamber 1, so that the silicon substrate 2 is not damaged by the charged particles.

By the way, the excitation energy Em of the metastable excited species is also important as another cause of inducing damage to the substrate to be etched. That is, the display stand energy E d (Displace
When a metastable excited species with an energy E+s higher than ment energy reaches the surface of the substrate to be etched, it causes damage to the surface of the substrate to be etched. For example, when the substrate to be etched is the silicon substrate 2, the energy Ed is 12.9 eV, and the gas for generating metastable excited species is He gas or N.

When gas is used, the energy of the metastable excited species of both gases Em (He” (2LS); 20.6aV, H
e”(2”S); 19.8eV, N6”('P
, ) : 16.7eV, Ne”(3P2) ;16
．． 6 eV) is higher than the energy Ed of silicon, there is a risk that the crystal lattice on the surface of the silicon substrate 2 will be disturbed.

Nitrogen gas, which generates the metastable excited species N-(A320), which has energy Em lower than the energy Em of the metastable excited species of rare gases such as He gas and Ne gas, also has the advantage of being inexpensive. It is suitable as a gas for performing dry etching.However, even when nitrogen gas is used as a gas for generating metastable excited species, when generating metastable excited species by electric discharge, the energy Ed of silicon is When excited species with high energy Em are generated and these excited species with high energy Em collide with the surface of the silicon substrate 2, the silicon substrate 2
There is a risk of shifting the crystal lattice position on the surface.

By the way, active species with high energy Em are thought to be generated by collisions between nitrogen molecules and electrons or collisions between metastable excited nitrogen molecules, although this varies depending on the discharge conditions. Therefore, active species with high energy E ra exist in a region relatively close to the discharge part in the afterglow formed by the discharge. For example, when the flow rate of nitrogen gas is 0.2+*fi/ff1in, and microwave discharge of 2.45G& is performed with a microwave output of 200W, a pink color appears over approximately 10cm downstream from the metastable excited species generation section 6. Afterglow is formed,
In this region, a large amount of active species with high energy Ea+ exist.

On the other hand, the desired metastable excited species N 2m (A 3Σ, +)
Most of the transition is called the first regular band (Na(B”rIg)
→N, (A3Σu1)]. During this transition process, yellow light emission of 5g0n++ is observed, and its presence can be easily confirmed visually. From this point of view, the metastable excited species N−(A′Σu +
) to perform dry etching using 58
If conditions are selected in which afterglow around 0 nm is dominant, and a reaction region with process gas is formed in a spatial region where such yellow afterglow exists or downstream thereof, dry etching can be performed with extremely low damage. be able to.

In the dry etching apparatus shown in FIG. 1, when the nitrogen gas flow rate is 5 mjl/+ain and discharge is performed at a microwave output of 200 W without introducing a process gas, a yellow color of 580 nm is generated throughout the entire interior of the reaction chamber 1. Observed. Therefore, when etching is performed using the dry etching apparatus shown in FIG. 1, the excited species with energy Em higher than the energy Ed of silicon will not reach the surface of the silicon substrate 2, and the metastable excited species N2'' (A”Σu+) activates the process gas, but the metastable excited species N, *(A3Σu+
) has energy Em of 6. ．． 2 eV, and the energy Ed of the silicon substrate 2, which is the substrate to be etched.
is 12,9eV, so the metastable excited species N,”(A
Since the energy E m of 3Σu + ) is sufficiently smaller than the energy Ed of silicon, N2'(A
3Σu+) collides with the surface of the silicon substrate 2, the surface of the silicon substrate 2 is not damaged.

In the dry etching apparatus shown in FIG. 1, the ion collector 7 is used as a means for suppressing the arrival of charged particles, but by applying a magnetic field as the means for suppressing the arrival of charged particles and bending the path of the charged particles, the ion collector 7 is used as the means for suppressing the arrival of charged particles. A method that prevents charged particles from colliding with the surface may be used.

Furthermore, in an apparatus that utilizes a metastable excited species having an energy E11 smaller than the energy Ed of the crystal of the substrate to be etched, the entire surface of the substrate to be etched is composed of a single crystal; It can be used not only when etching, but also when the part to be etched is part of the surface of the substrate to be etched, and different materials are exposed in other parts, as is typical in semiconductor processes. Needless to say, it can be done.

FIG. 2 is a diagram showing another dry etching apparatus according to the present invention. In FIG. 0, 14 is a light source, 15 is a lens,
16 is a light transmission window.

In this dry etching apparatus, the process gas that flows out from the gas storage section 8 and is introduced into the reaction chamber 1 is generated in the metastable excited species generation section 6, passes through the ion collector 7, and is introduced into the reaction chamber 1. At the same time, the reaction is excited by the energy of the light projected from the light source 14, passed through the lens 15 and the light transmission window 16, and irradiated into the reaction chamber 1, resulting in a synergistic effect between the two. The reaction proceeds efficiently.

In addition, in this dry etching device.

The light emitted from the light source 14 uniformly irradiates the silicon substrate 2, but the light emitted from the light source 14 may be light with pattern information, such as light that has passed through a mask, beam-like light such as a laser, etc. Good too. In such a case, there is an added effect that a desired location on the surface of the silicon substrate 2 can be selectively etched. In addition, the light source 14
Effective examples include laser light sources such as carbon dioxide lasers and excimer lasers, and gas discharge tubes that emit a strong spectrum in the ultraviolet region, such as Hg lamps, Hg-X5 lamps, and metal halide lamps. Further, in this embodiment, the silicon substrate 2 is irradiated with a light beam at right angles, but a method in which a light beam parallel to the silicon substrate 2 is passed through may also be used.

FIG. 3 is a diagram showing another dry etching apparatus according to the present invention. In FIG. 1, 17 is a pre-chamber for carrying the silicon substrate 2 into the reaction chamber 1, and 18 is a pre-chamber for carrying the silicon substrate 2 into the reaction chamber 1 after the etching process is completed. A rear chamber for carrying out the silicon substrate 2, 19 a partition wall between the reaction chamber 1 and the front chamber 17, 20 a partition wall between the reaction chamber 1 and the rear chamber 18, 23 and 24 each a front chamber 17, This is an exhaust device that exhausts the rear chamber 18.

In this dry etching apparatus, when the etching process in the reaction chamber 1 is completed, the partition wall 20 is opened,
The silicon substrate 2 in the reaction chamber 1 is transported to the rear chamber 18,
At the same time, bulkhead 19 was opened.

The silicon substrate 2 installed in the pre-chamber 17 is the reaction chamber 1
inserted within. Subsequently, after the partition walls 19 and 20 are closed, the silicon substrate 2 newly introduced into the reaction chamber 1 is etched.

In this dry etching apparatus, there are two preliminary chambers adjacent to one reaction chamber 1, namely a pre-treatment chamber 17 and a post-treatment chamber 18.
is provided, and the front chamber 17 and the rear chamber 18 are equipped with an exhaust device i.
Since the air is continuously evacuated at steps 23 and 24, outside air does not flow into one reaction chamber 1 when the etching process of the silicon substrate 2 is completed and the process proceeds to the next step. As a result, the step of re-evacuating the inside of the reaction chamber 1 to a desired degree of vacuum can be omitted or shortened, and problems inherent to the dry etching apparatus caused by outside air, such as air or water vapor, flowing into the reaction chamber 1 can be eliminated, i.e. Reaction chamber 1
Since the air and water vapor adsorbed inside reduce the activity of the coating-stabilized excited species, the problem of longer etching time can be overcome, and the etching throughput can be improved.

Furthermore, by adding a light source, lens, light transmission window, etc. as shown in Fig. 2 to the apparatus shown in Fig. 3, the synergistic effect between the photoexcitation reaction and the deexcitation reaction of metastable excited species can be utilized. Needless to say, the etching efficiency is further improved.

In the above embodiment, the case where the substrate to be etched is the silicon substrate 2 has been described, but the present invention can also be applied to the case where the substrate to be etched is another substrate. In this case, when the energy Ed of the crystal of the substrate to be etched is smaller than the energy Ed of the silicon substrate 2, if nitrogen gas is used as the gas for generating metastable excited species, the excited species N2 with energy Em around 11 eV will be generated.
(C3rIu) are generated at the same time, so the excited species N, (C
3rTu) has a high possibility of damaging the substrate to be etched. Therefore, it is preferable to set discharge conditions that suppress the excited species N, (C3rIu) from flowing into the reaction chamber 1, and allow the metastable excited species N2II (A3Σu+) to flow into the reaction chamber 1 dominantly. Further, in the above embodiment, nitrogen gas was used as the gas for generating metastable excited species, but other gases such as rare gases such as argon gas and xenon gas may also be used as the gas for generating metastable excited species. , when argon gas is used, Ar'(3Po) with energy Em of 11 and 7 eV, Ar'('P,) with energy Em of 11 and 5 eV can be used, and xenon gas can be used. In this case, the energy E1
Xe” (3P, ) where 1 is 9.5eV, energy E11
Xe' (3P, ) with a voltage of 8 and 3 eV can be used. Further, in the above-described embodiment, the metastable excited species generating section 6 that uses microwave discharge is used as a means for generating metastable excited species, but one that uses high frequency discharge may also be used.

In addition, as a process gas, SF or SF can be used depending on the purpose.

CCI, CF, C, C1, C1, F2, etc. may be used.

〔Effect of the invention〕

As explained above, in the dry etching apparatus according to the present invention, charged particles can be prevented from reaching the substrate to be etched, so that dry etching can be performed with extremely low damage. in this way,
The effects of this invention are remarkable.

[Brief explanation of the drawing]

1 to 3 are views showing a dry etching apparatus according to the present invention, respectively. 1... Reaction chamber 2... Silicon substrate 3...
・Nitrogen gas storage section 6... Metastable excited species generation section 7... Ion collector 8... Process gas storage section 13... Exhaust device agent Patent attorney Junnosuke Nakamura t l Figure 2

Claims (1)

[Claims] 1. A reaction chamber for accommodating a substrate to be etched, an exhaust means for evacuating the reaction chamber, a means for generating a metastable excited species for generating a metastable excited species, and the metastable excited species described above. In a dry etching apparatus having a means for introducing a metastable excited species into a reaction chamber and a process gas introducing means for introducing a process gas containing a halogen element into the reaction chamber, the metastable excited species can be excited by the means for generating a metastable excited species. A dry etching apparatus characterized by comprising an arrival suppressing means for suppressing charged particles generated together with the seeds from reaching the substrate to be etched. 2. Dry etching according to claim 1, characterized in that an ion collector is used as the arrival suppressing means, and the ion collector is provided at a connecting portion between the reaction chamber and the metastable excited species introduction means. Device. 3. The dry etching apparatus according to claim 1 or 2, wherein nitrogen gas or rare gas is used as the gas for generating the metastable excited species. 4. Claim 1 or 2, wherein the substrate to be etched is a silicon substrate, and nitrogen gas, argon gas, or xenon gas is used as the gas for generating the metastable excited species. The dry etching device described. 5. The method according to any one of claims 1 to 4, characterized in that a metastable excited species having an excitation energy lower than the display stand energy of the crystal of the substrate to be etched is used for activating the process gas. The dry etching apparatus according to any one of the above. 6. Using nitrogen gas as the gas for generating the metastable excited species, connect the connection part of the reaction chamber with the process gas introducing means to 58 in a state where the process gas is not introduced.
6. The dry etching apparatus according to claim 5, wherein the dry etching apparatus is located in or downstream of a spatial region where a yellow afterglow of 0 nm is observed. 7. The dry etching apparatus according to any one of claims 1 to 6, further comprising a light irradiation means for irradiating light for inducing a photoexcitation reaction into the reaction chamber. 8. The dry etching apparatus according to claim 7, wherein the light irradiation means is one that irradiates the surface of the substrate to be etched with light having pattern information. 9. Providing a preliminary chamber with an exhaust function adjacent to the reaction chamber, and carrying in the substrate to be etched through the preliminary chamber;
A dry etching apparatus according to any one of claims 1 to 8, characterized in that the dry etching apparatus carries out unloading. 10. The preliminary chamber is separated into a pre-chamber for carrying the substrate to be etched into the reaction chamber and a post-chamber for carrying out the substrate to be etched from the reaction chamber. A dry etching apparatus according to claim 9. 11. A connecting portion between the reaction chamber and the metastable excited species introduction means is provided on the most upstream side of the reaction chamber, a gas jet port of the process gas introduction means is provided on the downstream side, and the The dryer according to any one of claims 1 to 10, wherein a substrate to be etched is provided, and a connecting portion between the reaction chamber and the exhaust device is provided downstream thereof. Etching equipment.