JP2768760B2 - Resist ashing device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Field of Industrial Application) The present invention relates to an improvement in a resist ashing method.

(Prior art) Conventionally, as a method of ashing the resist formed on the substrate, the substrate was exposed to an ozone atmosphere by DA Balon and CO Kung of GE in 1972, or ultraviolet rays were irradiated in an ozone atmosphere. After that, a method of ashing a resist has been developed, and thereafter, various improved methods have been proposed. For example, O ₃ and N ₂ O in 200~300nm in an atmosphere of gas, a method of the ultraviolet 260~210nm ashing the resist by irradiating the resist on the substrate is disclosed in JP-B-64-4024 . Japanese Patent Application Laid-Open No. 63-266825 discloses that ultraviolet rays of 175 nm, 194 nm and 254 nm are irradiated under an oxygen-containing atmosphere containing ozone.
An ashing method that irradiates a resist on a substrate heated to 100 to 200 ° C. and regulates the ultraviolet illuminance on the resist surface to 50 mW / cm ² or more is disclosed.

By the way, the decomposition rate of the resist by the ashing method described above requires several minutes for a film thickness of 1 μm. When the illuminance, substrate temperature, and O ₃ concentration of the ultraviolet light on the resist surface are increased, an ashing rate of about 1 μm / min can be obtained depending on conditions. However, an increase in the illuminance of ultraviolet rays and an increase in the heating temperature cause problems such as damage to elements formed in advance on a substrate (especially a semiconductor substrate) and oxidation by ozone, and the control of these conditions naturally increases the ashing rate. There is a limit. In a semiconductor manufacturing process, the resist is exposed to plasma, various active gases, ions, and the like. For example, a phenol novolak-based resist undergoes three-dimensionalization and changes in chemical structure due to crosslinking, and is exposed to an ozone atmosphere or exposed to an ozone atmosphere. However, there is a problem that ashing cannot be performed at a sufficiently high rate by the conventional ashing method of irradiating ultraviolet rays.

(Problems to be Solved by the Invention) The present invention provides a method for quickly decomposing a resist on a substrate under atmospheric pressure (under normal pressure) without exposing it to a high temperature of 200 ° C. or more and strong ultraviolet rays, thereby efficiently removing the resist. It is an object of the present invention to provide a resist ashing apparatus having a simple structure.

[Structure of the Invention] (Means for Solving the Problems) A resist ashing apparatus according to claim 1 of the present invention comprises: a processing container for processing a substrate on which a resist is formed under atmospheric pressure; And an excited gas generating means for generating an excited gas by discharging a gas containing a fluoride at atmospheric pressure.

Examples of the substrate include a glass substrate and a semiconductor substrate.

As the resist, for example, various resists such as a novolak-based resist can be used.

As the above-mentioned fluoride, for example, CF ₄ , SF ₆ , NF ₃ , C ₂ F ₆
And the like.

The resist ashing apparatus according to claim 2 of the present invention is a processing container for processing a substrate on which a resist is formed under atmospheric pressure, and is connected to the processing container and discharges a gas containing a fluoride under atmospheric pressure. It is characterized by comprising: an excited gas generating means for generating an excited gas; and an ozone generating means connected to the processing container and generating ozone.

When the excited gas generated by the excited gas generating means and the ozone generated by the ozone generating means are introduced into the processing vessel, it is desirable that the ratio of the excited gas to the ozone be 0.5% by volume or more.

In the resist ashing apparatus according to the first and second aspects of the present invention, it is possible to add a heating means to improve an ashing rate of the resist on the substrate disposed in the processing container. When the resist is heated by such a heating means, the temperature is preferably set to 180 ° C. or less so as not to thermally damage the substrate.

In the resist ashing apparatus according to the first and second aspects of the present invention, if necessary, ultraviolet irradiation means for irradiating ultraviolet light having an energy intensity that does not damage elements formed on the substrate may be additionally provided.

(Operation) According to the resist ashing apparatus according to claim 1 of the present invention, an excited gas generated by discharging a gas containing a fluoride by an excited gas generating means at atmospheric pressure is introduced into a processing vessel, and the inside of the processing vessel is formed. By spraying the excitation gas under atmospheric pressure onto the resist on the disposed substrate, the resist is simply exposed to an ozone atmosphere, or damage to an element formed on the substrate as in a conventional method of irradiating ultraviolet rays under an ozone atmosphere. The resist can be ashed efficiently under atmospheric pressure without problems such as oxidation and oxidation.

According to the resist ashing apparatus according to claim 2 of the present invention, the excited gas generated by discharging the gas containing fluoride by the excited gas generating means at atmospheric pressure and the ozone generated by the ozone generating means are introduced into the processing vessel. By spraying the excitation gas and ozone at atmospheric pressure onto a resist on a substrate placed in this processing container, the substrate is exposed to an ozone atmosphere or exposed to ultraviolet light in an ozone atmosphere, as in a conventional method. The resist can be efficiently ashed under the atmospheric pressure without causing a problem such as damage to the element formed in the semiconductor device. However, with respect to the ashing rate, although only the excitation gas generated by discharging the gas containing fluoride by the above-described excitation gas generation means at atmospheric pressure is slightly lower than that of the apparatus that blows the resist on the substrate,
The possibility of contaminating the substrate or the like can be avoided as compared with the case where the excitation gas alone is introduced into the processing container.

Further, the resist ashing apparatus according to claims 1 and 2 of the present invention is not as large as an apparatus for ashing a resist under a vacuum atmosphere because the processing vessel for angling the resist on the substrate is placed under atmospheric pressure. No evacuation means is required, and handling properties can be improved.

(Example) Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

Embodiment 1 FIG. 1 is a partially cutaway schematic view showing an ashing apparatus used for resist ashing of this embodiment. The quartz cell 1 is housed in a heater box 2. In the quartz cell 1, a substrate holder 3 is disposed so as to face a connecting portion (blow-out portion) of a transport pipe 5 described later. A discharge tube 4 for discharging a gas containing a fluoride at atmospheric pressure is connected to the quartz cell 1 via a transport tube 5.
An on-off valve 6 is interposed in the transport pipe 5.

The discharge tube 4 includes a tube body 7 having both ends sealed and an upper portion of the side wall to which the gas transport tube 5 is connected. A glass tube 8 whose upper end is integrated with the upper wall of the tube body 7 is inserted into the tube body 7. Inside the glass tube 8, a mesh electrode 9 is arranged along the longitudinal direction of the glass tube 8. A wound electrode 10 is wound around the outside of the glass tube 8 at a predetermined interval. A power supply 11 is connected to the electrodes 9 and 10. The glass tube 8
Is connected to an introduction pipe 12 for supplying a gas containing a fluoride to the glass tube 8.

An ozonizer 14 is connected to the quartz cell 1 via a transport pipe 13. The transport pipe 13 is provided with an on-off valve 15. An O ₂ gas introduction pipe 16 is connected to a lower portion of the side wall of the ozonizer. The quartz cell 1
Is connected to an exhaust pipe 17.

Next, a method for ashing a resist using the ashing apparatus shown in FIG. 1 will be described.

First, a novolak-based resist (trade name: OFPR-800, manufactured by Tokyo Ohkasha Co., Ltd.) was applied on the silicon substrate on which the elements were formed.
After drying, a resist film having a thickness of 1.5 μm was coated, a resist pattern was formed by photolithography, and the underlying film was selectively etched and patterned using the resist pattern as a mask. Then, as shown in FIG. The silicon substrate 18 with the remaining resist pattern was held by the substrate holder 3 of the quartz cell 1.

Next, the on-off valve 15 of the gas transport pipe 13 on the ozonizer 14 side was closed. Subsequently, a predetermined amount of CF ₄ gas is supplied from the gas introduction tube 12 of the discharge tube 4 into the glass tube 8, and a high voltage of 50 Hz and 10 kV is applied between the mesh electrode 9 and the winding electrode 10 from the power supply 11. The CF ₄ gas supplied to the glass tube 8 was discharged by atmospheric pressure excitation. This excited gas is passed through the transport pipe 5 into the quartz cell 1 heated to 150 ° C.
The resist pattern was ashed by supplying for 10 minutes under the condition of hr.

Example 2 As in Example 1, the silicon substrate 18 with the resist pattern remaining was held by the substrate holder 3 of the quartz cell 1. Subsequently, O ₂ gas is supplied from the gas introduction pipe 16 to the ozonizer 14 for 24 hours.
Ozone at a concentration of about 110 g / Nm ³ was generated by an ozonizer, and the ozone was introduced into a quartz cell 1 heated to 150 ° C. by a heater box 2 through a transport pipe 13 at a rate of 20 / hr. In the same manner as in Example 1, the CF ₄ gas was discharged in the discharge tube 4 at atmospheric pressure, and the excitation gas was passed through the transport tube 5 into the quartz cell 1 for 2 / hr, 5 / hr, and 10 / hr.
Supplied under the following conditions. By supplying these gases for 10 minutes, the resist pattern on the silicon substrate in the quartz cell 1 was ashed.

Comparative Example Ashing was performed in the same manner as in Example 2 except that the supply of the excitation gas obtained by discharging the CF ₄ gas at atmospheric pressure to the quartz cell was reduced to zero.

The decrease in the thickness of the resist pattern after ashing in Examples 1 and 2 and Comparative Example was measured by a lambda ace film thickness meter. The result is shown in FIG. Note that the measurement result of the film thickness decrease was corrected by the tally step.

As apparent from FIG. 3, in the comparative example in which the supply of the excitation gas obtained by discharging the CF ₄ gas at atmospheric pressure is zero, the resist ashing rate is about 0.12 μm / 10 minutes. On the other hand, when the excitation gas is supplied at a rate of 2 / hr (addition amount to ozone gas; 0.5% by volume) as in Example 2, the resist ashing rate becomes about 0.4 μm / 10 minutes, and the supply of the excitation gas becomes zero. It turns out that it increases about 3 to 4 times compared with it. Further, even if the supply amount of the excitation gas is further increased, the ashing rate of the resist does not increase rapidly but increases only slowly.

On the other hand, in the method of Example 1 in which only the excitation gas obtained by discharging the CF ₄ gas at atmospheric pressure is supplied to the quartz cell, the ashing rate of the resist is 1.4 μm / 10 minutes, which indicates that the ashing rate is significantly improved.

Reference Example As shown in FIG. 2, as in Example 1, the silicon substrate 18 with the remaining resist pattern was held by the substrate holder 3 of the quartz cell 1. Subsequently, as in the second embodiment, ozone having a concentration of about 110 g / Nm ³ is generated by an ozonizer (not shown), and the ozone is passed through the transport pipe 13 to the heater box 2.
Is supplied into the quartz cell 1 heated to 150 ° C. at a rate of 20 / hr, and, similarly to the first embodiment, the excited gas obtained by atmospherically discharging the CF ₄ gas using a discharge tube (not shown) is transported. 5
To the transport tube 13 at a rate of 2 / hr. That is, without separately supplying ozone and the excitation gas into the quartz cell 1, the gases were mixed before the quartz cell 1, and then the ozone added with the excitation gas was supplied into the quartz cell 1 to perform ashing.

As a result, although the improvement of the ashing rate was recognized as compared with the method of ashing using only ozone, the ashing rate as high as in Examples 1 and 2 could not be realized. This is due to the fact that the active gases F ^* and HF in the excited gas are easily lost in the ozone because the gases are mixed before the ozone and the excited gas are supplied into the quartz cell 1. it is conceivable that.

In the above example, CF ₄ was used as the gas containing fluoride.
Using a gas, it can achieve a similar effect by using the excitation gas atmospheric pressure discharge gas containing other fluoride such as SF ₆ was confirmed.

In the above example, the heating was performed under the condition that the substrate was heated at 150 ° C., but it was confirmed that the ashing can be performed efficiently even at the normal temperature.

[Effects of the Invention] As described in detail above, according to the present invention, a resist on a substrate is rapidly decomposed under atmospheric pressure without being exposed to a high temperature of 200 ° C. or more or strong ultraviolet rays which cause damage to the substrate. A resist ashing apparatus having a simple structure that can be efficiently removed can be provided.

[Brief description of the drawings]

FIG. 1 is a partially cutaway schematic view showing an embodiment of a resist ashing apparatus according to the present invention, FIG. 2 is a schematic view of a main part showing a resist ashing apparatus used in a reference example, and FIG.
FIG. 4 is a characteristic diagram showing a relationship between a supply amount of an atmospheric pressure discharge gas (excitation gas) of CF ₄ and an ashing depth (decrease in film thickness) of a resist. DESCRIPTION OF SYMBOLS 1 ... Quartz cell, 2 ... Heater box, 3 ... Substrate holder, 4 ... Discharge tube, 5, 13 ... Transport tube, 14 ... Ozonizer, 18 ... Silicon substrate.

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-60-254730 (JP, A) JP-A-63-115343 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) H01L 21/3065

Claims (2)

(57) [Claims] 1. A processing vessel for processing a substrate on which a resist is formed under atmospheric pressure, and an excitation for generating an excitation gas by discharging a gas containing a fluoride at atmospheric pressure connected to the processing vessel. A resist ashing apparatus, comprising: gas generating means. 2. A processing container for processing a substrate on which a resist is formed under atmospheric pressure, and an excitation device connected to the processing container for discharging a gas containing a fluoride under atmospheric pressure to generate an excitation gas. A resist ashing apparatus comprising: a gas generation unit; and an ozone generation unit connected to the processing container and configured to generate ozone.