JPH0521336B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a photochemical reaction method, and particularly to a method for rapidly vaporizing and decomposing an organic layer present on a substrate and removing it.

[Background of the invention]

Various methods have been used to remove the photosensitive resin present on wafers, but the UV ozone method is attracting attention because of its advantages such as easy automation, easy maintenance, and less damage to the wafer. There is. An example of the UV ozone method is shown below using Figure 3. Inside the chamber 1, there is a susceptor 2 for placing the wafer 3, and a resistance heater 7 for heating the wafer 3 via the susceptor 2.With oxygen gas being supplied into the chamber 1 from the gas supply nozzle 4, Ultraviolet light (UV) can be irradiated onto the wafer 3 by a low-pressure mercury lamp 5. The low-pressure mercury lamp 5 used has strong wavelengths of 185 nm and 254 nm. With this device, a wafer 3 coated with a photosensitive resin is placed on a susceptor 2 and irradiated with ultraviolet rays, and after a predetermined period of time, the photosensitive resin layer on the wafer 3 is vaporized, decomposed, and removed. This principle is based on a reaction in which molecular bonds (e.g. C-C, C-H bonds) in the photosensitive resin layer are decomposed by the energy of ultraviolet rays.
It is thought that ozone and oxygen radicals generated by irradiating oxygen with ultraviolet rays react with these unbonded carbon atoms, hydrogen atoms, etc., resulting in a vaporization reaction that produces carbon dioxide, water, etc. There is.

FIG. 4 shows the influence of the wafer temperature Tw on the vaporization decomposition rate R of the photosensitive resin, which was determined through experiments. R is strongly influenced by Tw, and as Tw is increased, R increases dramatically. But Tw
At 300℃, most of the photosensitive resin on the wafer was vaporized and decomposed at a high rate as shown in Figure 4.
It was found that some components that are extremely difficult to decompose locally remained, and that it would take much longer to decompose all of these components than when Tw was 150°C.

Figure 5 shows how the maximum residual film thickness t of a 1 μm thick photosensitive resin layer decreases as the ultraviolet light irradiation time T increases as the wafer temperature Tw increases.
This is a comparison between 150 and 300℃. Tw is
At 300℃, the film thickness t decreases rapidly due to the initially high rate of vaporization, but it takes a long time to vaporize and decompose the refractory components, and eventually Tw reaches 150℃.
It can be seen that it takes a longer time than when

The reason why persistent components were generated when the wafer temperature Tw was set to 300℃ is not clear, but the local temperature distribution on the wafer causes a difference in the amount of thermal expansion of the photosensitive resin. This is thought to be due to the accumulation phenomenon. Note that the temperature at which the hardly decomposable component is generated differs depending on the type of photosensitive resin.

As described above, in the conventional technology, the effect that the rate of vaporization and decomposition of the photosensitive resin is high when the wafer temperature is high cannot be fully utilized, and the operation has to be performed at a lower temperature for a long time.

In addition, related technologies include UV Resist−Stripping for High−Speed and
Damage−Free Process／Exten and Abstracts
of the 15th Cont.on Solid State Devices and
Materials Tokyo 1983.Kiyoshi Ozawa etal.／
Described in Fujitsu Lab. Ltd.

[Purpose of the invention]

An object of the present invention is to eliminate such drawbacks of the prior art and to provide a method capable of vaporizing and decomposing an organic layer at high speed.

[Summary of the invention]

The present invention involves the steps of placing a substrate with an organic layer on its surface on a susceptor placed in a chamber, introducing oxygen into the chamber, and increasing the temperature of the substrate to 150°C while irradiating the substrate with ultraviolet rays. The time required to remove the organic layer on the substrate is reduced by gradually increasing the amount of organic layer on the substrate until it is decomposed and removed.

[Embodiments of the invention]

FIG. 1 shows an example of a photosensitive resin removal apparatus suitable for carrying out the method of the present invention. The chamber 11 has a susceptor 1 for installing the wafer 13.
2, and a gas supply nozzle 14 inside the chamber 11.
Light is irradiated onto the wafer 13 from the light source 15 while O ₂ gas is supplied from the wafer 13 . Although a low-pressure mercury lamp is used as the light source 15, other light sources that emit light at ultraviolet wavelengths may also be used. Wafer is resistance type heater 1
Heat at 7. The output of the resistive heater 17 is adjusted by a wafer temperature adjustment device 19. With such a device, the wafer 1 is placed on the susceptor 12 which has been heated to 150°C by the resistance heater 17.
3 and irradiated with ultraviolet rays in an oxygen atmosphere. A signal indicating that the wafer 13 has begun to be irradiated with ultraviolet light is input to the wafer temperature control device 19 by a transmitter (not shown), and the output of the resistive heater 17 is gradually increased based on a preset sequence. The sequence includes the thickness of the photosensitive resin layer based on previous experiments.
By the time the wafer becomes about 200nm, the wafer temperature Tw has reached 300℃.
Set it so that

The solid line in Figure 2 is an example of the results of this experiment, and shows the pattern of increase in resistance heater output,
The increase pattern of the wafer temperature Tw from 150℃ and the change in the photosensitive resin layer thickness t on the wafer are shown below.
It is shown in relation to the UV irradiation time on the wafer surface. In the figure, for comparison, the data when Tw was kept constant at 150°C is shown by a broken line. As is clear from Figure 2, if the temperature of the substrate is gradually increased from 150°C until the organic layer on the substrate is decomposed and removed, the time required to remove the photosensitive resin layer is reduced by the conventional method (Tw = 150
It was possible to shorten the time to about 1/3 of that at 30°F (°C), confirming the effectiveness of this method.

FIG. 6 shows an application example of the present invention, in which a protective film (such as wax) made of an organic substance is removed from a substrate. The chamber 21 has a base body 23 to which a protective film is attached, and the base body 23 can be irradiated with ultraviolet light while oxygen is supplied from the gas supply nozzle 24 . A plurality of lamp-type heaters 27 are used to heat the base 23, and the blinking of the lamp-type heaters is adjusted according to a sequence pre-installed in the base temperature control device 29.

The solid line in FIG. 7 is an example of a sequence used to vaporize and decompose the protective film and remove it from the substrate.
It also shows changes in the number of lamp-type heaters turned on and the duration of ultraviolet irradiation on the substrate surface. When the substrate enters the chamber 21, all the lamp type heaters 27 are turned on to rapidly heat the surface of the substrate. When the surface reaches a certain temperature, a part of the lamp heater 27 is temporarily turned off, and thereafter, as the protective film thickness t decreases, the number of lamp heaters turned on is sequentially increased.
Although the surface temperature of the substrate 23 changes in steps due to this sequence, the effects of the present invention are similarly exhibited. In FIG. 7, a processing example in which the substrate temperature is kept constant is shown by a broken line, and in contrast, the processing time of this example was about 1/4. The unique effects of this example are that it can be applied to substrates that are not flat, that the temperature adjustment sequence can be simplified by adjusting the substrate surface temperature by blinking a lamp heater, and that it has an organic protective film. This can also be applied to the vaporization and decomposition of

〔Effect of the invention〕

By implementing the present invention, the time required to remove the organic layer can be shortened to 1/3 to 1/4 of the conventional method.

[Brief explanation of the drawing]

Fig. 1 is a cross-sectional view of an embodiment of the present invention, Fig. 2 is a diagram showing the embodiment and effects of the present invention based on the experimental results conducted using the apparatus shown in Fig. 1, and Fig. 3 is a diagram of the conventional A cross-sectional view showing the device, Fig. 4 is a diagram showing the relationship between the vaporization decomposition rate of photosensitive resin and wafer temperature, and Fig. 5 is a diagram showing the difference in the change in photosensitive resin layer thickness over time when the wafer temperature is different. , FIG. 6 is a sectional view of an apparatus according to an applied example of the present invention, and FIG. 7 is a diagram showing the results of an experiment conducted using the apparatus shown in FIG. 6. 1... Chamber, 2... Susceptor, 3... Wafer, 4... Gas supply nozzle, 5... Low pressure mercury lamp,
6... Gas discharge nozzle, 11... Chamber, 12
... Susceptor, 13 ... Wafer, 14 ... Gas supply nozzle, 15 ... Light source, 16 ... Gas discharge nozzle, 17 ... Resistance type heater, 21 ... Chamber,
23...Base body, 24...Gas supply nozzle, 25...
...Low pressure mercury lamp, 26...Gas discharge nozzle, 29...
...Substrate temperature control device.

Claims (1)

[Claims] 1. A step of placing a substrate having an organic layer on its surface on a susceptor placed in a chamber, and introducing oxygen into the chamber and controlling the temperature of the substrate while irradiating the substrate with ultraviolet rays. A photochemical reaction method comprising the step of gradually increasing the temperature from 150°C until the organic layer on the substrate is decomposed and removed.