JP2718092B2 - Ashing apparatus and method for manufacturing semiconductor device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Summary] The present invention relates to an apparatus for ashing a resist film used in the manufacture of a semiconductor device and an ashing method using the same, which suppresses a decrease in ashing rate in a low-temperature region of 200 ° C. or lower. The aim is to make it possible to perform ashing process in low temperature range quickly, to prevent heavy metal contamination due to ashing of the resist film and to improve productivity. An ashing apparatus comprising: a heating support; and an ashing apparatus for performing an ashing process on the substrate to be processed, which is supported on the heating support and heated, and wherein a gas introduction port for introducing a gas containing O atoms into the plasma transport unit. Is provided,
When the plasma including H atoms generated in the plasma generation unit passes through the plasma transport unit, the plasma is mixed with the gas including O atoms introduced from the gas inlet and reaches the substrate to be processed. .

[Industrial applications]

The present invention relates to an apparatus for ashing a resist film or the like used for manufacturing a semiconductor device and an ashing method using the same.

[Conventional technology]

FIG. 2 is a diagram for explaining a conventional incinerator using oxygen gas plasma and an incineration method using the same. In the figure, 11 is a plasma generation unit, 12 is a plasma transport unit,
Reference numeral 13 denotes a heating support, reference numeral 20 denotes a gas exhaust port, reference numeral 19 denotes a substrate to be processed, on which an unnecessary resist film or the like is deposited. Further, the plasma generating unit 11 includes a waveguide 14, a quartz window 16, a gas inlet 15, a plasma generating chamber 17, and a shower plate 18.

In the figure, O ₂ gas introduced from a gas inlet 15 is turned into plasma in a plasma generation chamber 17 by an alternating electric field of micro (μ) waves guided from a waveguide 14. The generated O ₂ gas plasma passes through the shower plate 18, flows down in the plasma transport section 12, and reaches the substrate 19 to be processed. Then, the atomic oxygen (O) contained in the O ₂ gas plasma reacts with the resist film adhered to the substrate 19 to be ashed. The O ₂ gas plasma after the reaction is exhausted from the gas exhaust port 20. During the ashing process, the substrate to be processed 19 is heated to a predetermined temperature by the heating support 13.

The straight line 30 in FIG. 3 shows the temperature dependence of the incineration rate by the above-described incineration method. The microwave output is 1.5 kw, the pressure in the incinerator is 0.8 Torr, the O ₂ flow rate is 1 SLM, This shows the characteristics when the resist on the substrate 19 to be processed is OFPR-800 (manufactured by Tokyo Ohka). As is clear from the figure, the incineration rate strongly depends on the temperature of the substrate 19 to be processed, and it is necessary to increase the temperature of the substrate 19 to increase the ashing rate. For example, an incineration rate of about 4500 A / min at a temperature of 180 ° C. increases to about 15000 A / min at a temperature of 220 ° C.

Ozone ashing is also known in addition to the above-described O ₂ down-flow ashing (ashing), but at a temperature of 180 ° C. or lower, the ashing rate decreases as in the O ₂ down-flow ashing. In the case of down-flow ashing using a mixture of O ₂ gas and a small amount of halogen gas, the ashing rate does not significantly decrease even in a low temperature range of 180 ° C or less, but since the substrate to be processed is over-etched, LSI and the like are not used. Not suitable for ultra-fine processing.

[Problems to be solved by the invention]

In the semiconductor manufacturing process, it is desirable to shorten the ashing time as much as possible from the viewpoint of productivity and the like. For this reason, usually 200 ~ 250 ℃ which can increase the incineration rate
In many cases, a substrate to be processed such as a semiconductor wafer is heated to perform an ashing process. However, the temperature of the semiconductor wafer is 200 ° C
In this case, heavy metals such as iron, nickel, aluminum, and copper contained in the ashed resist film contaminate the semiconductor wafer to induce crystal defects or increase device leak current. Causes problems such as lowering the production yield. The present invention suppresses a decrease in the ashing rate in a low-temperature region of 200 ° C. or less, thereby enabling a rapid incineration treatment in a low-temperature region, thereby preventing heavy metal contamination due to incineration of a resist film and producing the same. The purpose is to improve the performance.

[Means for solving the problem]

An object of the present invention is to provide an ashing apparatus that includes a plasma generating unit, a plasma transport unit, and a heating support, and performs an ashing process on a substrate to be processed, which is supported by the heating support and heated. Is provided with a gas inlet for introducing a gas containing O atoms, and when the plasma containing H atoms generated in the plasma generating unit passes through the plasma transport unit, the O atoms introduced from the gas inlet are An incinerator characterized by being mixed with a gas containing the gas to reach the substrate to be processed, or by generating O-containing plasma and transporting the O-atom to the substrate to be processed. A method for manufacturing a semiconductor device is characterized in that the method includes a step of mixing with a gas to be included and ashing a film on the substrate to be processed with the mixed gas.

(Operation)

According to the present invention, H ₂ generated in the plasma generation section
On the way to the substrate to be processed through the plasma transport section, the gas plasma mixes with and reacts with the gas containing O atoms introduced from the gas inlet provided in the plasma transport section, and reacts with OH.
Yields a group. Therefore, the resist film etc. on the substrate to be processed and OH
And the like cause a reduction reaction, which makes it possible to suppress a decrease in the ashing rate in a low-temperature region as compared with the conventional oxidation reaction with atomic oxygen.

〔Example〕

FIG. 1 shows an incinerator for explaining an embodiment of the present invention. In the figure, 1 is a plasma generation unit, 2 is a plasma transport unit, 3 is a heating support, 10 is a gas exhaust port, 9
Denotes a substrate to be processed, on which an unnecessary resist film or the like is adhered. The plasma generating unit 1 includes a waveguide 4, a gas inlet 5, a quartz window 6, a plasma generating chamber 7, and a shower plate 8.
A gas inlet 21 is provided.

In the figure, H ₂ gas introduced from a gas inlet 5 of a plasma generator 1 is turned into plasma in a plasma generation chamber 7 by an alternating electric field of a μ-wave guided from a waveguide 4. When the generated H ₂ gas plasma passes through the shower plate 8 and flows down in the plasma transport unit 2, it mixes with the NO ₂ gas introduced from the gas inlet 21 provided on the side wall of the plasma transport unit 2. Reacts to produce OH groups. And the O
The H ₂ gas plasma containing the H group reaches the substrate 9 to be processed, and reacts with the resist film to ash it. The plasma after the reaction is exhausted from the gas exhaust port 10. During the ashing process, the substrate 9 to be processed is heated to a predetermined temperature by the heating support 3.

The straight line 40 shown in FIG. 3 shows the temperature dependence of the incineration rate obtained by the above incineration method.
H ₂ gas 600SCCM diluted to 30% was introduced from the gas inlet 5, a waveguide 4 frequency 2.45 ± 0.1 GHz, power 1.5KW mu
The graph shows the characteristics when a wave is introduced and when a NO ₂ gas of 600 SCCM is introduced from the gas inlet 21. Compared with the conventional incineration device using oxygen downflow and the characteristics represented by the straight line 30 obtained by the incineration method using it, the incineration rate in the low temperature region of 200 ° C or higher has been improved. Is evident.

For example, when the temperature of the substrate 9 to be processed is 200 ° C., the incineration rate when the incineration apparatus according to the present invention is used is about 11000 A / min.
It is inferior to the ashing rate of the conventional oxygen downflow ashing of about 15000 A / min, but when the temperature is 160 ° C., the ashing rate of the present invention is about 4300 A / min, which is about 2500 A / min of the conventional example. It is about 1.7 times that of min.

The gas introduced from the gas introduction section 21 is not limited to NO ₂ gas, but any gas containing O atoms as a constituent component is sufficient. The reason why the H ₂ gas is diluted with the Ar gas is to prevent danger such as a flash explosion, and there is no difference from the case of using pure H ₂ gas from the viewpoint of the effect of the present invention.

〔The invention's effect〕

As described above, according to the present invention, a gas containing O atoms is mixed with H ₂ gas plasma, and by using the reacted gas, the ashing rate is increased in a low-temperature region of 200 ° C. or less with less heavy metal contamination. The substrate to be processed can be ashed without lowering, and the productivity and quality of the semiconductor device can be improved.

[Brief description of the drawings]

 FIG. 1 is a schematic sectional view showing an embodiment of the present invention, FIG. 2 is a schematic sectional view showing a conventional example, and FIG. In the figure, reference numerals 1 and 11 denote a plasma generating section, 2 and 12 a plasma transport section, 3 and 13 a heating support, 4, 14 a microwave waveguide, 5, 15 a gas inlet, 6, 16 a quartz window. 7 and 17 are plasma generation chambers, 8 and 18 are shower plates, 9 and 19 are substrates to be processed, 10 and 20 are exhaust ports, 21 is a gas inlet port, 30 is a temperature characteristic of an ashing rate according to a conventional example, 40 is the temperature characteristic of the incineration rate according to the present invention.

Claims (2)

(57) [Claims] An ashing apparatus, comprising: a plasma generating section, a plasma transport section, and a heating support, wherein the ashing apparatus performs an ashing process on a substrate to be processed which is supported and heated by the heating support. A gas introduction port for introducing a gas containing O atoms in the plasma generating section,
When the plasma containing atoms passes through the plasma transport unit, the plasma is mixed with a gas containing O atoms introduced from the gas inlet and reaches the substrate to be processed. 2. A plasma containing H atoms is generated and mixed with a gas containing O atoms during transportation of the plasma onto a substrate to be processed, and the mixed gas is used to ash a film on the substrate to be processed. A method for manufacturing a semiconductor device, comprising the steps of: