JPS60225427A - Removing method of photosensitive resin - Google Patents

Abstract

PURPOSE:To enable removing even a photo resist processed by dry etching by processing a sample at first with a hydrogen radical and then with an oxygen radical. CONSTITUTION:In a main process chamber 5 housing a sample 20, a discharge tube 6 for generating a hydrogen radical and an Hg-Xe lamp 7 for generating an oxygen radical are provided. The discharge tube 6 is a pipe made of stainless steel and a copper rod 7 is provided inside as an electrode. An RF of 13.56MHz is supplied from a power source 8 through a matching network 9. Meanwhile, the Hg-Xe lamp 7 is provided with a window 11 made of MgF2 to avoid absorption of shorter wavelength light and the optical pass to the main process chamber is an N2 atmosphere. This equipment can remove the resist processed by dry etching in a short time.

Description

[Detailed description of the invention] [Technical field to which the invention pertains] The present invention relates to a method for removing photosensitive resin,
In particular, the present invention relates to improvements in methods for removing photosensitive resin (photoresist) used for pattern formation in semiconductor manufacturing processes.

[Prior art and its problems]

The general idea for removing organic matter is to incinerate it through the action of oxygen atoms (radicals). Conventionally, this has been carried out by immersing the sample in a mixed solution of sulfuric acid/hydrogen peroxide and boiling it to generate oxygen atoms. Also,
After forming the AI wiring, AJ cannot be used because it dissolves in acid, so a weak organic acid whose main component is carbolic acid has been used instead.

However, with the introduction of dry etching technology mainly based on reactive ion etching, a problem has arisen in that photoresist that has undergone a dry etching process is difficult to remove by the above method. Therefore, a new photoresist removal method was developed, which uses oxygen plasma.
Ashing method was developed. In general, a sample is placed in a cylindrical reaction chamber made of quartz, an oxygen atmosphere is created, and PF power is capacitively applied from a flat electric pole placed around the outside of the reaction chamber to generate plasma. This is a method in which organic matter (photoresist) is incinerated by the action of oxygen radicals and oxygen ions. In this method, the gas temperature increases in the plasma, and the photoresist that has undergone the dry etching process can be easily removed.

However, it has recently become clear that this method also has serious problems. This is a phenomenon in which the gate insulating films of JD and MO8 type transistors and capacitors are destroyed by the action of charged particles in plasma. An overview of this phenomenon will be explained using drawings.

First, FIG. 1(a) is a cross-sectional view of an MO8 type capacitor. Using a P-type (100) plane silicon substrate 1 with a resistance of 0.1 to 0.3 Ω, an element isolation region 2 is formed by selective oxidation, and a gate oxide film 3 of 40 OA is formed in a dry oxygen atmosphere. Then, a polycrystalline silicon film is deposited by low pressure vapor phase epitaxy (4000A) and 1000℃ at 1000℃.
Phosphorus diffusion is performed for 0 minutes to make it n-type. Next, an electrode/< turn is formed by one step of photolithography, and the polycrystalline silicon is etched along this pattern to form the electrode 4. ) and (C) in Figure 1 show the oxide film 3 when the photoresist is removed in a sulfuric acid-hydrogen peroxide mixed solution and when it is removed using an oxygen plasma ashing device.
This is a histogram showing the breakdown voltage yield. It is clear that the oxide film 3 is easily destroyed when oxygen plasma is used.

In order to avoid this problem, methods of ashing the resist by photoexcitation of ozone or oxygen have recently been studied. However, a resist that has not undergone any treatment can be removed by photoexcitation with ozone or oxygen, but a resist that has undergone a dry etching process is difficult to remove.

[Purpose of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to provide a photosensitive resin removal method that can remove photoresist that has undergone a dry etching process.

[Summary of the invention]

The inventor of the present invention conducted extensive research to clarify the reason why photoresist that has undergone a dry etching process is difficult to be removed by ozone and oxygen radicals, and as a result, the following was discovered.

That is, the resist surface layer is 8i0. After dry etching of the film, it is fluorinated due to the etching gas, and after dry etching of Al, it is chlorinated. Positive resists are generally made by bonding quinone diazide to novolak resin (-norformalin resin), but the sites to be converted into quinone diazide include not only the methylene group in the novolac resin but also the benzene ring. It extends to Halogen atoms have high electronegativity, and when bonded to a carbon atom, the electrons in the carbon atom are drawn toward the halogen atom, reducing the electron density on the carbon atom.

As a result, it is thought that the reactivity toward oxygen radicals, which are the desired nuclei, decreases, making it difficult to be removed by oxygen radicals. However, if you use a reagent with high reactivity against balogens such as hydrogen,
It is possible to extract the halogen atom bonded to the carbon atom, and after the halogen atom is extracted, it can be removed by oxygen radicals.

The present invention is based on the above findings, and is characterized by first allowing hydrogen radicals to act on the sample, and then oxygen radicals to act on the sample.

[Embodiments of the invention]

An embodiment of the present invention will be described below.

FIG. 2 is a schematic diagram of an apparatus used in an embodiment of the present invention. A sample 20 supported on a stage (not shown) is placed in the main processing chamber 5, and a discharge tube 6 for generating hydrogen radicals and Hg-X for generating oxygen radicals are placed in the main processing chamber 5.
Consists of e-rambuta. The discharge tube 6 is a stainless steel pipe and has a five-layer copper rod 7 therein as an electrode.

RIF power is supplied from a 13.56 MHz RF power source 8 via a matching network 9. A stainless steel mesh 10 is installed to prevent discharge from extending into the main processing chamber. On the other hand, for the HgXe') pumper, a window 11 made of KMgFt was used to prevent short wavelength light from being absorbed, and the optical path to the main processing chamber was set to N and atmosphere. Only the oil rotary pump 12 can be used for exhaust.

FIG. 3 is a diagram showing how the resist is removed.

The resist to be removed was 0FPR800 manufactured by Tokyo Ohka Co., Ltd. After coating, it was baked at 100°C for 3 minutes, and then OF4/H,
(1:1) exposed to mixed gas plasma for 10 minutes. FIG. 1(a) shows 0. Results when irradiated with Hg-X e lamp under 100 Torr (Yes.5
Even after 0 minutes, the resist film hardly decreased. 1st
) in the figure, the H2 gas in the discharge tube is ITorr, and 50
Apply 0W RF power and discharge to remove 10 H radicals.
After acting for a minute, O2 was set to 100 Torr and Hg-
This is the result when irradiating Xe and yp. The resist film decreased sufficiently quickly, and the effect of the present invention is clear.

〔Effect of the invention〕

According to the present invention, a resist that has undergone a sufficient dry etching process can be removed.

[Brief explanation of drawings]

Fig. 1 is a diagram showing the dielectric breakdown of an oxide film that occurs when using an oxygen plasma axor; Fig. 2 is a schematic diagram of the device used in an embodiment of the present invention;
The figure is a characteristic diagram showing how the resist film decreases in the conventional method and the present invention. DESCRIPTION OF SYMBOLS 1... 8i substrate, 2... Element isolation region, 3... Gate oxide film, 4... Polysilicon electrode, 5... Main process ★, 6... Discharge tube, 7... Hg-xe? pump, 8
...RF power supply, 9...Matching circuit, 10...
Metsy, 11...MgF! Window, 12...oil rotary pump, 13...pulp. Agent Patent Attorney Kensuke Chika (and 1 other person) No. 1
Figure 2

Claims (2)

[Claims] (1) A photosensitive resin removal method comprising the steps of applying hydrogen radicals to a sample and applying oxygen radicals or ozone to the sample. (2) The photosensitive resin removal method according to claim 1, characterized in that the hydrogen radicals and oxygen radicals are made to act on the sample under irradiation with ultraviolet light having a wavelength of 300 nm or less.