JPH01175231A - Ashing - Google Patents

Abstract

PURPOSE:To prevent contamination by a heavy metal due to an ashing operation of a resist while a heating temperature is lowered and to increase an ashing speed in a low-temperature region by a method wherein a heated object to be treated is treated by using an ashing medium gas containing an OH group to be generated by transforming, e.g., water or O2+H2O2 into a plasma. CONSTITUTION:A semiconductor water 11 is heated via a heating stage 20; a substance 21 containing an OH group is transformed directly into a plasma by microwave 23; a resist film and the like are ashed by using an ashing medium gas 12 containing the OH group. When water is used as the substance 21 and the microwave output is set at 1.5kW, an ashing speed is about 3100 [Angstrom /min] when a heating temperature of the semiconductor wafer 11 is 160 deg.C; this value is about 1.4 times as compared with about 2200 [Angstrom /min] for O2.

Description

[Detailed Description of the Invention] (4I! Essential) The present invention relates to an ashing method, particularly a processing method for heating a workpiece such as a semiconductor wafer to ash a resist film, etc. The heating temperature of the workpiece The purpose of this is to lower the ashing rate of the resist film, prevent heavy metal contamination due to ashing of the resist film, etc., and speed up the ashing speed at low temperatures.
The method includes ashing the workpiece using an ashing medium gas containing OH groups.

[Industrial application field]

The present invention relates to an ashing method, and more specifically to a processing method for heating a workpiece such as a semiconductor wafer to ash a resist film or the like.

[Conventional technology] FIG. 8.9 is an explanatory diagram of a conventional example.

FIG. 8 is a block diagram of a processing device according to a conventional ashing method, and shows an oxygen downflow ashing device. In the figure, l is a semiconductor wafer to be processed,
For example, it is a resist film that is no longer needed after being patterned on a semiconductor element in the process of forming a semiconductor device. 2 is a container for processing, 2a is a shower plate, 3 is μ
A waveguide that guides the wave 13, 4 a gas inlet for introducing oxygen 9, 5 an exhaust port for exhausting the ashed exhaust gas 10, 6 a quartz window that transmits the alternating electric field of the μ-wave 13, and 7 a 8 is a heating stage that supports and heats the semiconductor wafer 1; 9 is oxygen serving as the ashing medium gas; IO is the ashing exhaust gas; 13 is the energy of the plasma. μ wave (frequency 2.45±0.1GHz
).

These constitute an oxygen downflow ashing device.

FIG. 9 is an etching characteristic diagram related to a conventional ashing method, showing the etching characteristics of oxygen downflow ashing plotted on an Arrhenius plot.

In the figure, the horizontal axis is the heating temperature θ [°C] of the semiconductor wafer 1.
] plus the absolute temperature 273K, the reciprocal of temperature T, (1/T
) x 10 go (K-'), and the vertical axis is the ashing speed V
[Input/min] is expressed logarithmically.

In addition, as the oxygen downflow ashing condition, μ wave 1
The output of 3 is 1.5 (KW), and the pressure inside container 2 is 0.8.
(Torr), the flow rate of oxygen 9 is l (SLM), and the resist film on the semiconductor wafer 1 is 0FPR-800 (
In addition, the etching characteristics of oxygen downflow ashing in this case are as follows: The heating temperature θ of the semiconductor wafer l is 20°C from 220°C to 140″C.
From the relationship between (1/T) Become.

Therefore, in order to increase the ashing rate V [in/l1in], it is necessary to increase the heating rate θ ("C) of the semiconductor wafer l. For example, at a heating temperature of 220"C in the figure, the ashing rate V is approximately 15000 [in/+min
), and similarly, at a heating temperature of 180°C, the ashing rate V is approximately 4500 C person/-in).

In this way, the ashing speed V can be adjusted to
It is clear that the heating temperature greatly depends on the heating temperature.

In addition to oxygen downflow ashing, there is also ozone ashing with a heating temperature range of 250°C to 300°C.
At a heating temperature of 180° C. or lower, the ashing rate decreases as in oxygen downflow ashing.

In addition, downflow ashing using a mixed gas such as oxygen and a small amount of halogen gas is effective at low temperatures, but it overetches the semiconductor substrate, resulting in LS
Not suitable for ultra-fine processing such as I.

[Problems to be Solved by the Invention] According to the conventional oxygen downflow ashing, the heating temperature of the semiconductor wafer l at which the ashing speed V shown in FIG. Ashing processing of the resist film etc. on the semiconductor wafer 1 is performed while maintaining the temperature.

However, there are the following problems.

(2) If the heating temperature θ of the semiconductor wafer 1 is set to 200° C. or more, the semiconductor device will be contaminated by heavy metals such as iron, nickel aluminum, W4, etc. from inside the ashed resist film.

(2) Furthermore, as LSIs become more microfabricated, heavy metal contamination induces leakage currents and crystal defects in semiconductor devices, reducing production yields.

(2) When the heating temperature of the semiconductor wafer l is lowered from 220 DEG C. to 180 DEG C., the ashing rate decreases by about 1/3 from 15,000 people/in to 4,500 people/in, resulting in poor productivity.

The present invention was created in view of the problems of the conventional method, and it lowers the heating temperature of the workpiece, prevents heavy metal contamination due to ashing of the resist film, etc., and speeds up the ashing speed in the low temperature range. The purpose of this invention is to provide an ashing method that enables this.

[Means for solving problems]

In the ashing method of the present invention, as shown in FIG. 1 for its principle and as shown in FIGS. The present invention is characterized in that the workpiece 11 is incinerated, thereby achieving the above object.

[Effect]

According to the present invention, the heated workpiece is filled with an ashing medium gas containing OH groups.

Therefore, the structural material of the workpiece and the OH groups of the ashing medium gas containing OH groups undergo a reduction reaction, thereby making it possible to increase the ashing rate in a low temperature range compared to the conventional method.

〔Example〕

Next, embodiments of the present invention will be described with reference to the drawings.

2 to 7 are explanatory diagrams of an ashing method according to an embodiment of the present invention, and FIG. 2 shows a configuration diagram of a processing apparatus according to the ashing method of the first embodiment of the present invention.

In the figure, reference numeral 11 indicates a semiconductor wafer as a workpiece, such as a resist film that is no longer needed after being patterned on a semiconductor element in the process of forming a semiconductor device.

Reference numeral 12 denotes an ashing medium gas containing OH groups, which is a gas component obtained by converting the substance 21 containing OH groups into plasma and removing electrons e- and ionic components. In addition, OH group (hydroxyl group)
The substance 21 containing water (HtO), hydrogen peroxide (Hzo
z), ammonium hydroxide (NT(, 0T()), and alcohols (R-OF()), and in the experimental examples related to the embodiments of the present invention, H, O and H2O are used.

14 is a container for ashing the workpiece 11; 15 is a waveguide that guides the μ-wave 23 to the plasma generation section 19; 16 is a gas introduction port for introducing the substance 21 containing an OH group into the plasma generation section 19; This is an exhaust port for evacuating the container 14 and exhausting the exhaust gas 22 after ashing the resist film and the like.

18 is a quartz window that receives the alternating electric field of the μ-waves 23; 19 is a plasma generating unit that converts a substance 21 containing an OH group, such as H2O, into plasma using the μ-wave energy; and 20 is a plasma generator that supports the semiconductor wafer 11; This is a heating temperature stage for heating. Note that the heating stage 20 can control a heater (not shown) or the like by a temperature control means.

Nao, 14a is a grid-shaped shower plate;
Electrons e- and ions generated when a substance 21 containing H groups is turned into plasma are grounded through a container 14.

Further, 22 is an exhaust gas, which is evacuated by a rotary pump (not shown) or the like connected to the exhaust port 17. For example, a rotary pump etc. has a pressure of 0.8 (To
rr] etc.

Further, 23 is a μ wave as an energy source for converting the substance 21 containing one ○■ group into plasma to generate an ashing medium gas containing OH groups, and for example, the frequency is 2.45±0.1 GH.
z, output 1.5 (KW).

These constitute a downflow ansing device.

Note that in the ashing method according to the first embodiment, heat is applied to the semiconductor wafer 11 via a heating stage 20 while controlling the heating temperature, and the substance 21 containing an OH group is directly irradiated via the μ-wave 23. The resist film and the like on the semiconductor wafer 11 are ashed by the ashing medium gas 12 which is turned into plasma and contains OH and l.

FIG. 3 is a comparative illustration of the ashing method according to the first embodiment of the present invention and the conventional method based on the experimental data of the present inventors, and shows the etching characteristics of downflow ashing of oxygen versus water plotted by Arrhenius plot. It shows.

In the figure, the horizontal axis is the heating temperature θ [°
C] plus the absolute temperature 273K, the reciprocal of the temperature T, (1/
T)X 10'' (K-1), and the vertical axis represents the ashing speed V [in/ff1in] in logarithm.

Moreover, the substance 2 containing an OH group according to the first embodiment of the present invention
The etching characteristics of ashing the semiconductor wafer 11 by using water as the ashing medium gas 12 containing 0H7ji and ashing the semiconductor wafer 11 are shown by a straight line connecting points Δ. Note that the straight line connecting the ○ points is the etching characteristic of the conventional oxygen downflow ashing.

Note that the downflow ashing conditions for the first embodiment of the present invention are similar to the conventional example, such that the output of the μ wave 23 is 1.5
(KW), the pressure inside the container 14 is 0,8 (Tor
r) The flow rate of the water 21 was set to 1 (SLM), and the resist film on the semiconductor wafer 11 was set to 0FPR-800 (manufactured by Tokyo Ohka Products).

Further, its etching characteristics are such that the heating temperature θ [°C] of the semiconductor evaporator 11 is changed to 220°C via the heating stage 20.
The ashing rate of the resist film, etc. of the semiconductor wafer 11 is
It shows the relationship between person/, in).

Here, the downflow ashing of the ashing medium gas containing OH groups according to the first embodiment of the present invention will be compared with the oxygen downflow ashing according to the conventional example.

For example, the heating rate θ of the semiconductor wafer 11 is in a high temperature range of 180° C. or higher, that is, the heating temperature θ of the semiconductor wafer 11 is
The ashing speed V of the first embodiment of the present invention at 200'C is about 6500C/11in), which is inferior to the conventional example of about 9000C/-1n).

However, the heating temperature θ of the semiconductor wafer 11 is in a low temperature range of 180'C or less, that is, the heating temperature θ of the semiconductor wafer 11 is
The ashing speed V of the first embodiment of the present invention when = 160°C is approximately 3100 (man/1 lin), which is approximately 1.4 times the value of the conventional example (approximately 2200 C man/1 lin). become.

Therefore, in the first embodiment of the present invention, it is possible to improve the ashing rate by 1.4 times compared to the conventional example under the same conditions in a low temperature range where heavy metal contamination is relatively low.

FIG. 4 shows a configuration diagram of a processing device related to the ashing method according to the second embodiment of the present invention.

The difference from the first embodiment is that the ashing medium gas 12 containing OH groups is chemically reacted with oxygen gas plasma 31a and a substance 34 containing OH groups, such as hydrogen peroxide, above the semiconductor wafer 11. This is the point where it is being generated.

In the figure, components with the same names as those in the first embodiment have the same functions, so the explanation will be omitted.

24 is a container, 25 is a waveguide, 26a is a gas inlet for introducing oxygen 31 into the plasma generating section 29, 26b is a gas inlet for introducing hydrogen peroxide, etc. 34 into the container 24, 27 is an exhaust port, and 28 is an exhaust port. a quartz window; 29 a plasma generation unit that converts oxygen 31 into oxygen gas plasma through the energy of the μ-wave 33;
30 is a heating stage, 31a is an oxygen gas plasma, 32
is an exhaust gas, 33 is a μ wave, and 34 is a substance containing an OH group, such as hydrogen peroxide. 24a is a shower plate, which constitutes down flow ashing manufacturing.

In the ashing method according to the second embodiment, heat is applied to the semiconductor wafer 11 via a heating stage 30 while controlling the heating temperature, and oxygen gas plasma 31a and hydrogen peroxide 34 are applied to the semiconductor wafer 11. A chemical reaction is caused above the semiconductor wafer 11, and the resist film and the like on the semiconductor wafer 11 are ashed using the ashing medium gas 12 containing OH groups.

FIG. 5 is a comparative explanatory diagram of the A:-sing method according to the second embodiment of the present invention based on the experimental data of the present inventors and the conventional example, and shows an Arrhenius plot of oxygen vs. oxygen + hydrogen peroxide. This shows the etching characteristics of downflow ashing.

In the figure, the horizontal axis is the reciprocal of temperature (
1/T) x 10'(K-'), and the vertical axis indicates the ashing speed V.

Moreover, the substance 3 containing OH group according to the second embodiment of the present invention
4, hydrogen peroxide is used to generate an ashing medium 12 containing OHg by oxygen gas plasma 31a, and the semiconductor wafer 1 is
The etching characteristics of ashing process 1 are shown by the straight line connecting the points to .

Note that the downflow ashing conditions of the second embodiment of the present invention are the same as those of the first embodiment, and its etching characteristics also vary depending on the heating temperature θ ("C) of the semiconductor wafer 11, 220'
Ashing speed V [in /
m1n) is shown.

Here, the downflow ashing of the ashing medium gas containing OH groups according to the second embodiment of the present invention will be compared with the oxygen downflow ashing according to the conventional example.

For example, as in the first embodiment, high temperature range (θ≧180'C)
, that is, the heating temperature θ of the semiconductor wafer 11 is 200°C.
The ashing speed V of the second embodiment of the present invention when
approximately -7000C person/-1n), compared to approximately 900C of the conventional example.
0 C person/-1n).

However, the ashing rate V of the second embodiment of the present invention in the low temperature range (θ = 180°C), that is, when the heating temperature of the semiconductor wafer 11 is θ = 160''C, is about 3500 (
(input/min), which is about 2200 [input/min] in the conventional example.
The value is about 1.7 times that of n ].

Therefore, as in the case of the first embodiment, in the second embodiment of the present invention, the ashing speed under the same conditions in a low temperature range with relatively little heavy metal contamination is improved by 1.7 times compared to the conventional example. It becomes possible to do so.

FIG. 6 shows a configuration diagram of a processing device related to an ashing method according to a third embodiment of the present invention.

Note that the difference from the processing apparatus according to the ashing method of Example 1.2 is the method of generating the ashing medium gas 12 containing OH groups.

In the figure, the same reference numerals and names as in the first embodiment have the same functions, so their explanation will be omitted.

61 is necessary for generating the ashing medium gas 12 containing OH groups,
Oxygen 31, a substance 21 containing an OH group, an inert gas 44, etc. are individually supplied to the plasma generating section 1 through valves 16a to 16c.
This is a gas introduction pipe to be introduced into 9. Note that 16a is a valve that controls injection of the inert gas 44, 16b is a valve that controls injection of oxygen 31, and 16c is a valve that controls injection of a substance containing an OH group. In addition, the inert gas 44 is OH
It serves as a carrier for the ashing medium gas 12 containing groups and has the effect of promoting the ashing process of the resist film and the like on the semiconductor wafer 11.

These components constitute a downflow ashing device according to the ashing method of the third embodiment.

Note that the ashing method according to the third embodiment applies heat to the semiconductor wafer 11 via the heating stage 20 while controlling the heating temperature, and heats the semiconductor wafer 11 using a heating stage 20 that contains a small amount of inert gas 44, oxygen 31, and OH groups. Substances 21, such as ammonium hydroxide, are introduced into the plasma generating section 19 through valves 16a to 16c, and are directly turned into plasma via the μ-waves 23. ashing the resist film, etc.

FIG. 7 shows a configuration diagram of another processing device related to the ashing method of each embodiment.

Note that the difference from the processing apparatus related to the ashing method of the first to third embodiments is that the plasma energy source for generating the ashing medium gas 12 containing OH groups is changed from the μ waves 23 and 33 to a high frequency power source. The point is that there is.

In the figure, numeral 35 is a container for generating plasma and processing the semiconductor wafer 11.

Further, 36 is a counter electrode that generates plasma, 37 is a support stand that supports a workpiece such as the semiconductor wafer 11, and 38 is an OH
a gas inlet for introducing a substance containing a group, such as water, 39
receives high frequency energy and converts the substance 41 containing OH groups into O
This is a plasma generation unit that generates an ashing medium gas 12 containing H groups.

Note that 40 is a heat source that heats the semiconductor wafer 11, and 41 is a substance containing an OH group such as water, hydrogen peroxide, ammonium hydroxide, or the like. Moreover, E is a high frequency power source for converting the substance 41 containing OH groups into plasma to generate the ashing medium gas 12 containing OH groups.

In addition, the frequency of high frequency power supply E is 13.56±IM Hz
It is. Further, 42 is an exhaust gas, 43 is an exhaust port,
These components constitute other processing equipment.

In this way, the heated semiconductor wafer 11 is filled with the ashing medium gas 12 containing OH groups.

For this reason, the constituent materials such as the resist film of the semiconductor wafer 11 and the OHI of the ashing medium gas containing OH groups undergo a reduction reaction, so that heavy metal contamination is relatively less in the low temperature range (θ <180') compared to the conventional example. Ashing speed V [on/
-11) can be accelerated by 1.4 to 1.7 times.

〔Effect of the invention〕

As explained above, according to the present invention, by incinerating a workpiece using an ashing medium gas containing OH groups, it is possible to improve the productivity of semiconductor devices in a low temperature range with little heavy metal contamination. It becomes possible to improve the production yield.

Therefore, it becomes possible to mold ultra-fine, highly integrated, and high-performance semiconductor devices.

[Brief explanation of the drawing]

Fig. 1 is a principle diagram of the ashing method of the present invention, Fig. 2 is a block diagram of a processing device related to the ashing method of the first embodiment of the present invention, and Fig. 3 is a diagram of the processing device according to the first embodiment of the present invention. A comparative explanatory diagram of the ashing method and a conventional example, FIG. 4 is a configuration diagram of a processing device according to the ashing method of the second embodiment of the present invention, and FIG. 5 is a diagram of the ashing method according to the second embodiment of the present invention. A comparative explanatory diagram of the method and a conventional example. FIG. 6 is a configuration diagram of a processing device related to the ashing method of the third embodiment of the present invention. FIG. FIG. 8 is a block diagram of a processing device according to a conventional ashing method, and FIG. 9 is an etching characteristic diagram according to a conventional ashing method. (Explanation of symbols) l, 11... Semiconductor wafer (workpiece), 2.14,
24.35... Container, 'la, 14a... Shower plate, 3.15.25... Waveguide, 4.16.26a, 26b, 3El=Gas inlet, 5.
17,27.43...Exhaust port, 6.18.28...Quartz window, 7.19,29.39...Plasma generation part, 8.20
．． 30... Heating stage, 9.31... Oxygen, 10.22.32.42... Exhaust gas, 12... O
Ashing medium gas containing H group, 13.33...μ wave, 21... Water (substance containing OH group), 34... Hydrogen peroxide (substance containing OH group), 36...
- Counter electrode, 37... Support stand, 40... Heat source, 41... Substance containing OH group, 44... Inert gas, E... High frequency power source. Ashing medium gas containing 120H group Figure 1: Principle diagram of the assoring method of the present invention @ Comparative explanatory diagram of the Ano/Fugu method according to the first embodiment of the present invention and the conventional example Figure 3: The method of the present invention Comparative diagram of the Anonong method according to the second embodiment and the conventional example. Fig. 8 Schematic diagram of processing equipment related to the Ano/Fugu method Fig. 9 Diagram of etching/gating process related to the conventional Ano/Fugu method

Claims (6)

[Claims] (1) An ashing method characterized by ashing the workpiece (11) with an ashing medium gas (12) containing OH groups while heating the workpiece (11). (2) The ashing medium gas (12) containing OH groups is
The ashing method according to claim 1, wherein the ashing method is generated by directly converting a substance (21) containing a group into plasma. (3) The ashing medium gas (12) containing OH groups is generated by hydrogen peroxide (34) and oxygen gas plasma (31a). ashing method. (4) The ashing medium gas (12) containing OH groups is
The ashing method according to claim 1, characterized in that the ashing method is produced by mixing a substance (21) containing a group with oxygen (31) and turning the mixture into plasma. (5) The energy source for generating the OH group-containing ashing medium gas (12) is a 2.45±0.1 GHz μ wave (23
．． 33) or 13.56±1MHz high frequency power supply (E
) The ashing method according to claim 1. (6) The ashing method according to claim 1, wherein the ashing medium gas (12) containing OH groups contains an inert gas (44).