JPS6320833A - Ashing apparatus - Google Patents

Abstract

PURPOSE:To avoid some adverse effect of a plasma on e wafer and furthermore, increase reactivity to ozone as well as organic substances by separating an ashing chamber having a wafer from a discharge chamber and irradiating the wafer with light of Deep UV region to. CONSTITUTION:The following facilities: ashing chamber 1 housing a wafer 2, discharge chamber 5 using high frequency weves or microwaves which are connected to the ashing chamber 1, lamp chamber 8 having lamps 9 that irradiate low wavelength light to the wafer 2 installed in the vicinity of an asher, and exhausting means 11 and 12 connecting to the ashing chamber 1 are provided respectively. Under such a configuration, an effect of plasma to the wafer 2 can be avoided by separating the ashing chamber 1 housing the wafer 2 from the discharge chamber 5. Moreover, in addition to introducing gas excited by discharging the high frequency waves into the ashing chamberl, Deep UV light including 185nm and 253.7nm are irradiated. As a result, the above arrangements improve reactivity of ozone and resist end increase an etching speed of resist.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention (Industrial Application Field) The present invention relates to an ashing device, and more particularly to a device for etching resist formed on a wafer.

(Prior Art) Conventionally, a barrel-type device has been used as an ashing device for etching resist.

However, in this device, the wafer itself is exposed to plasma, so the f-
) Deterioration of device characteristics such as destruction is likely to occur. In particular, f-)
This becomes a problem for devices with a large degree of integration where the insulating film thickness becomes thinner.

Therefore, ozone cleaning using ultraviolet irradiation in an atmosphere of oxygen gas is being developed, but ultraviolet irradiation alone is insufficient to etch the resist, and the system loop requires a long processing time.

(Problems to be Solved by the Invention) The present invention has been made in view of the above circumstances, and by separating the ashing chamber in which the wafer is stored and the discharge chamber, the influence of plasma on the wafer is avoided, and An object of the present invention is to provide an ashing device that can increase the reactivity between ozone and organic matter by irradiating low wavelength light into an ozone atmosphere created from an excited gas generated by electric discharge.

[Structure of the Invention (Means and Effects for Solving Problems)] The present invention provides an ashing chamber containing a wafer, a discharge chamber connected to the ashing chamber using high frequency or microwave, and the ashing device. A lamp chamber having a rung provided close to the ashing chamber and irradiating the wafer with low wavelength light, and an exhaust means connected to the ashing chamber to avoid the influence of plasma on the wafer. and an increase in the etching rate of organic matter.

(Example) An embodiment of the present invention will be described below with reference to FIG.

1 in the figure is an ashing chamber that stores Weno 2 at the bottom. This ashing chamber 1 is provided with a Pirani gauge 3 that detects the pressure inside the chamber.

A discharge chamber 5 equipped with a high frequency power source 4 is connected to the ashing chamber 1 . Oxygen (02) gas is introduced into the discharge chamber 5 through a flow rate controller 6. A lamp chamber 8 having a quartz window 7 at the bottom is placed above the ashing chamber 1. In this lamp chamber 8, for example, three mercury lamps 9 and a reflecting plate 10 for these lamps are installed. Here, the wavelength 18 is determined by the mercury rung 9.
Ultraviolet light including 5 nm and 254 mm is irradiated onto the wafer 2 through the quartz window 7. A flow meter 11 is connected to the upper part of the lamp chamber 8, and the flow meter 11 is connected to the upper part of the lamp chamber 8.
03 generation due to UV light is prevented. Here, since the interior of the lamp chamber 8 is a N2 atmosphere, the strong reduction in the intensity of the 185 nm and 254 nm ultraviolet rays necessary for the ozone reaction is small. Further, cooling water is circulated on the surface of the lamp chamber 8 in order to prevent the temperature of the lamp chamber surface from rising due to UV light. An inverter type mechanical booster pump 12 and a rotary pump 13 are sequentially connected to the ashing chamber 1.

These pumps 12, 13 exhaust reaction products from etching. The seven bumps 12 can change the exhaust speed by controlling the rotation speed, and can control the pressure inside the ashing chamber 1. This pressure is
- Measured at 3.

Next, the operation of the ashing device shown in FIG. 1 will be explained.

■ When 03 is irradiated with 254 mm ultraviolet rays, it absorbs the ultraviolet rays, decomposes 03, and generates oxygen radicals (0'').On the other hand, ultraviolet rays with a wavelength of 185 nm decompose 02 and generate 03 (02+0→ 03).For this reason, in addition to the O produced by high-frequency discharge, the generation and decomposition of O3 is further promoted by ultraviolet irradiation. During this process, extremely reactive O" is produced. However, it reacts with organic substances such as resist on the wafer to form a volatile gas CO9CO2, and etching of the resist progresses. In general, the intensity of ultraviolet rays strongly depends on the distance between the lamp 9 and the wafer 2, but in the above example, the distance was set to about 5u.

■ When 02 gas is flowed at a flow rate of 0.2 L/-〇 and the ashing chamber is evacuated using the pump 12 so that the pressure becomes approximately 100 mTorr, the difference in resist etching speed due to the presence or absence of high frequency discharge is as follows. Become.

Without high frequency discharge...0120μyB/-
i - With or without high frequency discharge...0.45μm2
/- However, the high frequency discharge was performed with an applied power of 300W. As a result, when high-frequency discharge is used in combination, the increase is greater than when high-frequency discharge is not used, confirming that not only UV irradiation but also high-frequency discharge is extremely effective for resist etching.

■ Also, under the conditions of 02 flow -5110.2t/w-, the exhaust speed was changed to increase the pressure in the ashing chamber to 50.100.20.
When the etching rate of the resist was measured at 0 m Tor-r, the results shown in FIG. 2 were obtained.

As shown in the figure, there was a tendency for the etching rate to increase as the ashing pressure was lowered. Next, the pressure in the ashing chamber was kept constant at 50 mTorr, and the O2 flow rate was set at 0.
When the etching rate of the resist was measured by changing the values to 1, 0.2, and 0.4 t/cod, the results shown in Figure 3 were obtained. As shown in the figure, it can be seen that as the 0□ flow rate increases, the etching rate of the resist tends to increase.

According to the embodiment described above, by separating the ashing chamber 1, which houses the wafer 2, and the discharge chamber 5, it is possible to avoid the influence of plasma on the wafer 2. Also, Do to Weno S2 in the upper part of the ashing chamber 1. .

Since the structure includes a lamp chamber 7 equipped with a mercury lamp 9 etc. that irradiates UV light, gas excited by high frequency discharge is introduced into the ashing chamber l, and the 185
Irradiation with D@@p UV light containing wavelengths of 253.7 nm and 253.7 nm can significantly increase the reactivity of ozone and resist. Therefore, the etching rate of the resist can be increased. It is clear from FIGS. 2 and 3 that the resist can be etched more effectively by increasing the 02 flow rate and lowering the ashing pressure.

In addition, although the said Example described the case where high frequency discharge was used in the discharge chamber, it is not limited to this and microwave discharge may be used.

[Effects of the Invention] As detailed above, according to the present invention, it is possible to provide an ashing apparatus that can avoid the influence of plasma on etching materials and increase the etching rate by increasing the reactivity between ozone and organic matter.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of an ashing apparatus according to an embodiment of the present invention, FIG. 2 is a characteristic diagram showing the relationship between ashing pressure and renost etching speed according to the present invention, and FIG. FIG. 3 is a characteristic diagram showing the relationship between gas flow rate and resist etching speed. 1...Ashing chamber, 2...Wafer, 5...Discharge chamber, 8...Rung water, 9...Mercury lamp, )θ...
・Reflector, 11... Mechanical booster pump, 1
2...Rotary pump. Applicant's representative Patent attorney Takehiko Suzue (7”n/m:
n) 7y>')”;-force (m Torr ) (Prn/mi
n)

Claims (1)

[Claims] The ashing chamber includes an ashing chamber storing a wafer, a discharge chamber connected to the ashing chamber using high frequency or microwave, and a lamp provided close to the ashing device and irradiating the wafer with light in the deep UV range. 1. An ashing device comprising: a lamp chamber; and an exhaust means connected to the ashing chamber.