JPS62272539A - Resist removal method - Google Patents

Abstract

PURPOSE:To largely reduce a substrate damage at the time of removing a resist having a modified layer by removing by ashing the unmodified resist by diffusing gas containing ozone, and then removing by ashing the resist modified layer by an oxygen plasma. CONSTITUTION:When ashing, a substrate 1 to be processed is placed on a stage 2, and an oxygen (O2) is introduced from a gas inlet 6. This introduced oxygen (O2) is activated by an ozonizer 7, fed to a processing chamber 5, uniformly distributed by a gas dispersing plate 8 to be diffused to the main surface of the substrate 1 heated to the temperature. Unreacted resist layer on the substrate 1 is substantially completely removed by ashing by ozone (O3) in the reaction gas, and only the modified layer remains on the substrate 1. Then, the O3-ashed substrate 1 is plasma-processed, for example, by a sheet type plasma processor. In case of O2-plasma ashing, a plasma is generated between an anode 13 and a cathode 14, and the resist modified layer is completely removed by oxygen ions and radicals excited by the plasma.

Description

[Detailed Description of the Invention] 3. Detailed Description of the Invention [Summary] Resist removal comprising a step of removing an unaltered resist by ozone anothing and then removing a resist layer altered by ion bombardment, etc. by plasma ashing. Method.

[Industrial application field]

The present invention relates to a method for removing resist, and more particularly, to a method for completely removing a resist that has a large amount of deteriorated layer due to particularly strong ion bombardment during an ion implantation process without damaging a substrate.

As semiconductor circuits become larger and more sophisticated, the number of types of LSIs increases compared to conventional ICs, and it is inevitable that the production volume per type will decrease.

Therefore, single-wafer processing technology is often used in the manufacture of LSIs.

To form impurity-introduced regions such as base regions and source/drain regions in the above-mentioned single-wafer processing, an ion implantation technique is used in which impurity ions are acceleratedly implanted into the semiconductor substrate surface using a resist layer formed on the semiconductor substrate as a mask. used.

During this ion implantation, there is a phenomenon in which a degraded layer is formed due to the energy of the ions on the surface of the resist layer that is irradiated with accelerated impurity ions. There is a problem in that a large amount of the deteriorated layer is formed, making it difficult to remove the resist layer, and when removing the resist layer, the semiconductor substrate is seriously damaged, reducing the manufacturing yield of the above-mentioned LSI and the like.

Therefore, there is a need for a resist removal method that can completely remove a resist layer having an altered layer without causing significant damage to the substrate.

[Conventional technology]

Methods for removing resist that do not damage the substrate include sulfuric acid boiling and other wet processing methods, but it is nearly impossible to completely remove a resist layer that has a large amount of deteriorated layer using this wet processing method. .

Therefore, conventionally, a plasma ashing method using oxygen (0□) plasma or the like has been used to remove a resist layer having a deteriorated layer.

However, since this plasma ashing method promotes resist ashing by bombardment with ionized ions such as 0□, damage to the substrate is unavoidable.

Therefore, in an attempt to completely remove the resist layer, which is used as a mask for high-concentration ion implantation and has a large amount of altered layer,
When the plasma intensity is increased or the processing time is significantly extended, the damage to the substrate increases, resulting in a problem that the electrical characteristics of a semiconductor device formed on the substrate deteriorate.

[Problem that the invention seeks to solve]

The problem to be solved by the present invention is that conventionally, when removing a resist layer that caused a large amount of deteriorated layer, a large amount of damage was caused to the substrate.

[Means for solving problems]

The above-mentioned problem is solved by the process of removing unaltered resist by ashing by blowing ozone-containing gas, and then ashing and removing the deteriorated resist layer by oxygen plasma when removing a resist on which a deteriorated layer has been formed by ion bombardment. This problem is solved by the resist removal method according to the present invention.

[For production]

That is, in the method of the present invention, after the unaltered resist is completely removed by ozone ashing, which does not cause damage because it does not use plasma, only the remaining deteriorated layer is removed by plasma ashing, thereby causing no damage to the substrate. This greatly reduces the time required for plasma treatment, and significantly reduces damage to the substrate when removing a resist having an altered layer.

〔Example〕

Hereinafter, the present invention will be specifically explained by examples with reference to the drawings.

FIG. 1 is a schematic side sectional view showing an example of an ozone ashing device, and FIG. 2 is a schematic side sectional view showing an example of a plasma ashing device.

In this example, a mask is formed with a thickness of 1 μm on a silicon (Si) substrate, and an acceleration energy of 60
A substrate to be processed is used, which has a resist layer in which arsenic (^S) ions are implanted at KeV, dose it t X1015C1ll-2, and a large amount of altered layer is formed.

First, the substrate to be processed is inserted into an ozone (03) ashing device and subjected to the 03 ashing process.

For example, as shown in FIG. 1, the 03 ashing device has a stage 2 on which a substrate to be processed 1 is placed, a gas supply pipe 3 at the top, and a gas discharge port 4 connected to an exhaust duct.
The ozonizer 7 is connected to the tip of the gas supply pipe 3 and has a gas inlet 6. A gas dispersion plate 8 is disposed in the upper part of the processing chamber 5. , a heater 9 is provided inside the stage 2.

During the ashing process, the substrate 1 to be processed is placed on the stage 2.
Placed on top and heated to 200 to 300°C, oxygen (0□) gas is supplied from the gas inlet 6, for example, at 2j? /wi
Introduce at a flow rate of about n. This introduced oxygen (0□) is activated by the ozonizer 7 and becomes an oxygen gas containing, for example, about 5% ozone (03), that is, (0□+5%0.) reaction gas, and is led to the processing chamber 5. The gas is uniformly distributed by the gas distribution plate 8 and blown onto the main surface of the substrate 1 to be processed heated to the above temperature.

The unreacted resist layer on the substrate 1 to be processed is almost completely removed by ashing due to the ozone (0,) in the reaction gas, and only the degraded layer remains on the substrate 1 to be processed. The processing time is about 1 minute.

Note that this treatment is performed at normal pressure.

Next, the substrate 1 to be processed after the above O and ashing is
For example, 0□ plasma processing is performed using a single-wafer type plasma processing apparatus, and the altered layer deposited on the substrate 1 to be processed as a residue is completely removed.

For example, as shown in Fig. 2, a single wafer plasma processing apparatus
In a reaction vessel 12 having a gas inlet 10 at the upper part and a vacuum exhaust port 11 at the lower part, an anode 13 serving as a stage is disposed at the lower part, and a cathode 14 is disposed at the upper part opposite to the anode 13. The anode 13 and cathode 14 are connected to a high frequency power source 16 of, for example, 13.56 MIIz via a capacitor 15 on the cathode 14 side.

0□ For plasma ashing, the substrate to be processed 1 is placed on the anode 13, the gas inlet 02 is introduced at a predetermined flow rate, and the vacuum exhaust port 11 is evacuated at a predetermined rate to drain the inside of the reaction vessel 12. While reducing the gas pressure to, for example, about 2 Torr, high frequency power of about IKW is applied between the anode 13 and the cathode 14.
During this process, plasma is generated, and oxygen ions and radicals excited by the plasma completely remove the altered resist layer deposited as a residue on the substrate 1 to be processed.

In the substrate 1 to be processed used in this example, the time required to completely remove the deteriorated resist layer was about 10 seconds. With the above steps, the removal of the resist layer having the deteriorated layer was completed.

As shown in the above embodiments, in the method of the present invention, the unaltered resist layer, which accounts for most of it, is removed by the 03 ashes process that does not damage the substrate.
3. Only the resist deteriorated layer remaining after the ashing process is 0.
□The resist layer including the altered layer is completely removed by plasma ashing.

Therefore, the 0□ plasma ashing process, which conventionally took about 2 minutes, can be significantly shortened to about 10 seconds, and the amount of damage done to the substrate when removing the resist layer with the altered layer is greatly reduced. do.

As a result, the life span of minority carriers on the substrate 1 to be processed after the resist removal, that is, a silicon (Si) substrate, was improved by about 30% to 8 compared to when the conventional resist removal method was used.

Note that the method of the present invention is not limited to the single wafer processing shown in the above embodiments, but is of course applicable to hatch processing using a ring furnace type reaction vessel.

〔Effect of the invention〕

As explained above, according to the resist removal method of the present invention,
A resist layer that has a large amount of altered layers due to ion implantation or the like can be completely removed without causing major damage to the substrate.

Therefore, the present invention is effective in improving the manufacturing yield of LSIs and the like.

[Brief explanation of drawings]

FIG. 1 is a schematic side sectional view showing an example of an ozone ashing device, and FIG. 2 is a schematic side sectional view showing an example of a plasma ashing device. In the figure, 1 is a substrate to be processed, 2 is a stage, 3 is a gas supply pipe, 4 is a gas discharge port, 5 is a processing chamber, 6 is a gas inlet, 7 is an ozonizer, 8 is a gas distribution plate,
9 is a heater, io is a waste inlet, 11 is a vacuum exhaust port, 12 is a reaction vessel, 13 is an anode,
14 is a cathode, 15 is a capacitor, and 16 is a high frequency power source.

Claims (1)

[Claims] When removing a resist in which an altered layer has been formed by ion bombardment, the unaltered resist is removed by ashing by blowing gas containing ozone, and then the altered resist layer is removed by ashing by oxygen plasma. A resist removal method comprising the steps of: