JP2000077387A - Method and system for removing resist - Google Patents

Abstract

PROBLEM TO BE SOLVED: To attain a practical ashing rate without causing any damage on a substrate by removing resist using ozone of high concentration within a specified range in an atmosphere reduced below atmospheric pressure under a relatively low temperature condition within a specified range. SOLUTION: Ozone gas generated from an ozonizer 3 is concentrated to 10-40 vol.% by an ozone concentrator 5 and supplied into an ashing chamber 9 where a substrate 20 applied with resist is processed. An atmosphere in the ashing chamber 9 is kept at a pressure lower than the atmospheric pressure and a relatively low temperature condition between the room temperature and 300 deg.C. According to the arrangement, a practical ashing rate on the order of 5000 Å/min (500 nm/min) can be attained. Furthermore, resist can be removed without causing any damage on the substrate 20.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a technique for removing a resist applied to a semiconductor substrate such as a wafer.

[0002]

2. Description of the Related Art At present, the mainstream of resist ashing technology practically used in mass production processes in the fields of IC and liquid crystal is oxygen plasma. However, ashing using plasma may not only damage the underlayer, but also prevent complete ashing of the altered resist that has undergone ion implantation or the like. I have. Therefore, in recent years, a plasma-less ashing technique using ozone has been proposed.

[0003]

However, in the conventional plasmaless ashing technology using ozone, the ashing speed is much lower than that of the oxygen plasma ashing, and the actual situation is that the ashing speed has not reached the level of practical use. . The present invention pays attention to such a point, and an object of the present invention is to provide an ozone ashing technique that can withstand practical use.

[0004]

SUMMARY OF THE INVENTION In order to achieve the above-mentioned object, the present invention provides a method in which a chamber in which a semiconductor substrate coated with a resist is mounted is maintained at a reduced pressure atmosphere below atmospheric pressure. An ozone gas having an ozone concentration of 10 to 40 vol% is supplied, and the resist applied to the semiconductor substrate is removed under a temperature condition of room temperature to 300 ° C. According to a second aspect of the present invention, the ozone gas to be supplied to the chamber is obtained by concentrating ozone generated by an ozonizer by an adsorption type concentrator. Further, an invention according to claim 3 is an apparatus for removing the above-mentioned resist, comprising: an ozone gas concentrating apparatus;
It is characterized by comprising a storage tank for storing high-concentration ozone derived from this ozone concentrator, and a resist ashing chamber connected to the ozone storage tank through a high-concentration ozone supply path with a mass flow controller interposed. .

[0005]

According to the present invention, a high-concentration ozone having an ozone concentration of 10 to 40 vol% is used, and the resist is removed under a reduced pressure atmosphere below the atmospheric pressure and under a relatively low temperature condition of a room temperature to 300.degree. / Min (500nm
/ Min), which makes it possible to obtain an ashing speed that can withstand practical use, and removes the resist without damaging the substrate.

[0007]

FIG. 1 is a conceptual diagram showing an example of the embodiment. This resist removing apparatus is an oxygen storage container (1)
The oxygen supply path (2) derived from the ozonizer (3) is connected to the ozonizer (3), and the ozone supply path (4) derived from the ozonizer (3) is connected to the adsorption type ozone concentrator (5).
The high-concentration ozone lead-out path (6) derived from (5) is connected to an ozone storage tank (7), and the high-concentration ozone supply path (8) derived from the ozone storage tank (7) is connected to a resist ashing chamber (9).
It is constituted by connecting to.

[0008] An ozone gas discharge passage (10) extends from the outlet of the ozone concentrator (5) and the resist ashing chamber (9), and the ozone gas discharge passage (10) is connected to an ozone decomposer (11). It is configured to decompose and release the discharged ozone. An ozone recovery container (12) is connected to the ozone concentrator (5).
In (12), when the pressure of the adsorption cylinder in the ozone concentrator (5) rises abnormally, the gas in the adsorption cylinder is safely released and collected.

As shown in FIG. 2, the ozone concentrating device (5) is constituted by arranging three adsorption tubes (14) each filled with an adsorbent (13) for selectively adsorbing ozone. As the adsorbent (13) for selectively adsorbing ozone, high-purity silica gel having a purity of 99.95% or more is used, and a cooling jacket (15) for storing a brine made of ethanol on the outer periphery of each adsorption tube (14). The temperature of the adsorbent (13) is indirectly controlled by controlling the temperature of the brine layer with a tape heater wound around the outer wall of the cooling jacket (15).

[0010] Each of the adsorption cylinders (14) has an ozone adsorption step, an ozone stabilizing and increasing step, an ozone desorption step, respectively.
The cooling process is controlled so that the four processes are repeated as one cycle. When the required time in each process is T for the adsorption process, T / 2 for the ozone stabilization and pressure raising process, T for the ozone desorption process, and cooling. The process is set to T / 2, and the operation cycle of each adsorption cylinder (14) is shifted by 1/3.

[0011] In the ozone concentrating apparatus (5) configured as described above, one of the three adsorption tubes (14) becomes a desorption step, so that the concentrated ozone-rich gas is continuously discharged. Is derived. The ozone concentration of the ozone-rich gas desorbed in the desorption step changes stepwise during the step. However, once the ozone concentration is introduced into the ozone storage tank (7), the ozone concentration is averaged. Is supplied to the resist ashing chamber (9).

In the drawing, reference numeral (16) denotes a mass flow controller mounted on the ozone supply path (4), and (17) denotes a high-concentration ozone derivation path.
A mass flow meter attached to (6), and a mass flow controller (18) attached to the high concentration ozone supply passage (8).
Reference numeral (19) denotes a susceptor in which a heater disposed in a resist ashing chamber (9) is embedded, (20) denotes a semiconductor substrate such as a wafer mounted on the susceptor (19),
(21) is a water cooling pipe for cooling the resist ashing chamber (9).

Using the resist removing apparatus having the above-mentioned structure, 5 vol% of the ozone gas generated from the ozonizer (3) is concentrated to about 40 vol% by the ozone concentrating apparatus (5), and the concentrated ozone gas is supplied to the ashing chamber.
An embodiment in the case of processing a wafer coated with a resist by supplying it into (9) will be described below. The wafer used was a 6-inch wafer coated with a 2 μm-thick resist film.

The temperature of the susceptor (19) in the ashing chamber (9) is fixed at 147 ° C., the flow rate of the gas supplied to the ashing chamber (9) is fixed at 200 sccm, and the ashing speed when the supplied ozone concentration is changed is adjusted. As shown in FIG. From this result, it is understood that the ozone concentration increases linearly as the ozone concentration increases. And the ozone concentration 30vol%
5000 o / min and ozone concentration 40vol%
It can be seen that an ashing speed of 6000 ° / min can be obtained.

FIG. 4 shows the ashing speed when the gas flow supplied to the ashing chamber (9) is fixed at 200 sccm and the temperature of the temperature susceptor (19) is changed. From this result, the ozone concentration of 25 vo
In the case of 1%, the influence of the temperature is extremely large, and it can be seen that in the temperature range up to about 200 ° C., the ashing speed increases exponentially with the rise in temperature. On the other hand, when the ozone concentration is 5 vol%, which is the concentration of the ozone gas generated from the ozonizer, a tendency to saturate around 150 ° C. is recognized. This is presumably because the ashing reaction speed increases as the temperature rises, but the absolute amount of ozone required for the ashing reaction at 150 ° C. is insufficient.

FIG. 5 shows the relationship between the gas supply amount and the ashing speed when the ashing temperature is fixed at 126 ° C. and the ozone concentration is fixed at 25 vol%. According to this figure, there is no significant difference in the ashing speed in the range of the supply gas flow rate of 200 to 400 sccm. From this, it is considered that the reaction rate on the resist surface has entered the rate-determining stage.

[0017]

According to the present invention, the ozone concentration is 10 to 40 vo.
By removing the resist under a reduced pressure atmosphere below the atmospheric pressure and at a relatively low temperature of room temperature to 300 ° C. using ozone at a high concentration of 1%, 5000 ° C./min (50
A practical ashing speed of about 0 nm / min to 6000 ° / min (600 nm / min) can be obtained, and the resist can be removed without damaging the substrate.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram illustrating an example of an embodiment.

FIG. 2 is a schematic configuration diagram of an ozone concentrator.

FIG. 3 is a graph showing a relationship between an ozone concentration and an ashing speed.

FIG. 4 is a graph showing a relationship between a temperature and an ashing speed.

FIG. 5 is a graph showing a relationship between a gas flow rate supplied to an ashing chamber and an ashing speed.

[Explanation of symbols]

3 ozonizer, 5 ozone concentrator, 9 chamber, 20 semiconductor substrate.

 ──────────────────────────────────────────────────続 き Continued on front page F term (reference) 2H096 AA25 AA30 HA30 LA06 4G042 CA05 CB15 CE04 5F004 AA09 AA16 BB17 BB26 BD01 CA02 CA04 DA27 DB26 5F046 MA11 MA13

Claims (4)

[Claims] 1. A chamber (9) in which a semiconductor substrate (19) coated with a resist is mounted is maintained at a reduced pressure atmosphere below atmospheric pressure, and 10 to 40 vol.
A resist removing method configured to supply an ozone gas having an ozone concentration of 1 to remove the resist applied to the semiconductor substrate (20) at a temperature of room temperature to 300 ° C. 2. Ozone gas generated by an ozonizer (3) is concentrated by an adsorption-type ozone concentrator (5), and concentrated ozone concentrated by the ozone concentrator (5) is supplied to a chamber (9). The method for removing a resist according to claim 1. 3. An ozone concentrator for concentrating ozone gas.
(5), an ozone storage tank (7) arranged downstream of the ozone concentrator (5), and a resist ashing chamber connected to the ozone storage tank (7) through a high-concentration ozone supply path (8). (9) A resist removing apparatus in which a mass flow controller (19) is interposed in a high-concentration ozone supply path (8). 4. The resist removing device according to claim 3, wherein the ozone concentrating device is an adsorption type ozone concentrating device.