KR100290875B1 - Method for anisotropic etching by formation of polymer film - Google Patents

Abstract

PURPOSE: Provided is a method for anisotropic etching an etching film by forming a polymer film at lateral wall of the etching film, and at surface and lateral wall of the processing layer in etching process, using a plasma etching device. CONSTITUTION: The method comprises the steps of (i) patterning a processing layer for patterning an etching film on the upper of the etching film of conductor board, and loading the patterned sample into the plasma etching device; (ii) introducing a reactive gas between the upper and lower electrodes(11,12), applying electric field or both electric field and magnetic field to the electrodes to etch the processing layer by plasma discharge, thereby forming a polymer film at lateral walls of the processing layer and the etching film with a small possibility of ion collision, at the same time, etching the processing layer and the etching film with a large possibility of ion collision by chemical reaction by heavy ion collision to form a polymer film at surface of the processing layer.

Description

Anisotropic Etching Method by Forming Polymer Film

(A)-(E) is sectional drawing for demonstrating the conventional etching method.

2 (A) is a schematic view of the plasma etching equipment used in the present invention (B), (C) is a cross-sectional view for explaining the etching method of the present invention

* Explanation of symbols for main parts of the drawings

1. Semiconductor substrate 2. Etching film 3. Process layer 4. Polymer film

10. Reactor 11. Upper electrode 12. Lower electrode 13. Wafer chuck

14.Wafer 15.Dielectric board 16,17.Upper and lower power

TECHNICAL FIELD The present invention relates to anisotropic etch, and more particularly, to an anisotropic etch method using a polymer film, which is suitable for reducing the ratio of side etching by forming a polymer film on the side and the surface and side surfaces of the etching layer.

1 (A)-(E) are process cross-sectional views for explaining the prior art, which will be described below.

First, an etching film (all etching materials such as Poly-Ai, Si ₃ N ₄ , SiO _2, etc.) 2 is formed on the semiconductor substrate 1 having a flat surface as shown in FIG. 1A. After forming the process layer (all masking material) 3 on (2), the process layer 3 is patterned, and in the sample in which the process layer 3 pattern with a predetermined width was formed, an etching film was formed. An electric field and a magnetic field using an etching gas in an microwave and an etching by an electric field using an etching gas between two electrodes in the plasma reactor for anisotropic etching of (2). A process is performed by the etching method by this.

At this time, the total input in the reactor is tens or less (Torr) or less, and a power supply system for forming an electric field is a plasma type applied to the upper electrode and a RIE (Reative Ion Etching) type applied to the lower electrode.

In this case, the polymer film formed on the sidewalls of the etching layer 2 and the process layer 3 is formed by plasma discharge of a gas source containing carbon, or plasma of a gas source containing fluorine. Formation is related to the formation of unsaturated radicals generated by the discharge, or the formation by the etching product generated on the horizontal surface removed by the ion bombardment.

That is, the polymer film is formed during the anisotropic etching process of the etching film 2 by the above method, and is formed on the side of the etching film 2 to be positioned below the process layer 3 during the etching by plasma ( 2) to prevent undercut and laterally etching (Lateral Etch).

However, the sidewall etching of the etching layer 2 is prevented by the polymer film formed on the side during the etching process of the etching layer 2 by the conventional technique, and the side etching of the etching layer 2 is prevented according to the anisotropic etching. In addition, although the etching film 2 may be etched according to the anisotropic etching, there is a problem in which the position where the polymer film 4 is formed is unclear as shown in FIGS. 1B and 1E.

SUMMARY OF THE INVENTION The present invention has been made to solve the problems of the prior art, and an object of the present invention is to anisotropically etch an etching film by using a plasma etching apparatus to produce a polymer film during the etching process on the sidewall and the surface and sidewalls of the etching layer. have.

Referring to the accompanying drawings, an embodiment of the present invention for achieving the above object is as follows.

Figure 2 shows a schematic configuration of the plasma etching equipment used in the present invention, the upper electrode 11 is located above the reactor 10, the dielectric plate 15 is located below the upper electrode 11, the lower side The lower electrode 12 is positioned at a predetermined distance from the upper electrode 11 and is connected to the wafer chuck 13 that loads the semiconductor substrate 14 on the lower electrode 12.

The upper and lower electrodes 11 and 12 are connected to RF power sources 16 and 17, respectively.

However, the upper electrode 11 is a TCP (Transformer Coupled Plasma) type using a spiral coil.

FIG. 2B is a sample cross-sectional view for explaining the anisotropic etch of the present invention. All etching materials such as etching films (SiO ₂ , Si ₃ N ₄ , Poly-Si, MoSix, etc.) on the semiconductor substrate 1 are illustrated. (2), and a process layer (all masking materials such as SiO ₂ , Si ₃ N ₄ , Poly-Si, P / R, etc.) 3 is formed on the etching layer ₂ as a masking material. The process layer 3 is patterned for use as a masking film.

In order to anisotropically etch the etch film 2 of the sample on which the process layer 3 is patterned, a sample is loaded into a plasma etch apparatus and the etch film 2 is etched in a plasma atmosphere.

In this case, the plasma is formed by injecting a reaction gas between the upper and lower electrodes 11 and 12 and generating an electric field or an electric field + a magnetic field to generate plasma.

By the generation of this plasma, etching proceeds by chemical reaction of positive ion bombardment with directional and material to be etched.

Plasma is formed by the process layer 3 being etched during the etching process, so that the deposition amount is increased on the side of which ion collision probability is low, and the chemical reaction by ion collision occurs because of the ion collision probability in the plane.

The polymer film is formed by plasma formation by gas with plasma discharge, plasma formation by recombination with saturation formation, and recombination of etch by-products generated by ion collision and reactant gas in a plane.

Accordingly, as shown in FIG. 2C, the polymer film is formed by the plasma discharge during the plasma etching of the etching layer 2 using the process layer 3 as a mask, and the plane of the sidewalls of the etching layer 2 and the process layer 3 by plasma discharge. And formed on the side wall, the etching layer 2 of the bottom of the process layer 3 is anisotropic etching proceeds without undercut (undercut) and lateral etch (lateral etch) is possible to selectively etch.

An embodiment of the anisotropic etching having such an etching characteristic is as follows.

As shown in FIG. 2B, an oxide film (SiO ₂ ) is deposited on the semiconductor substrate 1 as an etching film at about 300 ° C., and polysilicon is deposited at 2500 ° C. at a temperature of 640 ° C. An etching film 2 made of silicon is formed.

The polysilicon is injected with acenic (As) at a concentration of 1.0 × 10 ¹⁶ cm ^{−3 with} an energy of 80 KeV.

The sample is then heat treated for 10 minutes at a temperature of 900 ° C while injecting N ₂ / O ₂ (1%) gas into the diffusivity.

Next, a photosensitive film is coated on polysilicon and cured at a temperature of 100 ° C. to 140 ° C., followed by a photo-etching process to form a photoresist pattern as the process layer 3.

In a state in which a sample formed of the above materials is loaded in a plasma etching apparatus, the pressure in the reactor; 1.5 mTorr, electrode spacing 6 cm, reaction gas Cl ₂ + O ₂ gas and C ₂ HCl ₂ F ₃ + SF ₆ = 20 The process is performed under the conditions of +20 SCCM, electrode temperature; 20 ° C., RF power; 13,56 MHz, upper electrode power = 300 to 600 W, lower electrode; 10 W to 60 W.

Then, MoSix is sputtered at a temperature of 250 ° C. to form 300 Å to form an etch film 2 and a photoresist pattern on the etch film 2 to form a process layer 3. Pressure in the reactor to anisotropically etch MoSix in this sample; 10 mTorr, electrode spacing; 6 cm, reaction gas BCl ₃ + N ₂ + SF ₆ = 20 + 20 + 20SCCM, electrode temperature; 50 ° C, top electrode = 400W, bottom The etching process was performed under the conditions of 100W.

(However, the electrode may be supplied with microwave or Halocarbon gas as a reaction gas.)

After the plasma etching process, the photosensitive film pattern, which is the process layer 3 on the polysilicon film and the MoSix film, was etched with UV + ozone (O ₃ ) gas at 300 ° C. for 3 minutes and observed to form a polymer film. Then, the concentrations of carbon (C) and fluorine (F) are examined on the surface of the etching film 2 etched by Auger analysis.

The present invention forms a polymer film on the sidewalls of the etch film 2 and the surface and the sidewalls of the process layer 3, thereby making it easy to control the vertical etching thickness of the etch film 2, and to undercut and side surfaces. Anisotropic etching is performed to prevent the etching (Lateral etch), etc., thereby forming a precise pattern.

Claims (6)

Patterning a process layer 3 for patterning the etch film 2 over the etch film 2 on the semiconductor substrate 1 and loading the sample into a plasma etching equipment; The process layer 3 having a low ion collision probability as the process layer 3 is etched by a plasma discharge of the gas mixture by inserting a reaction gas between the upper and lower electrodes 11 and 12 and applying an electric field or an electric field + magnetic field. And the polymer film 4 is formed on the sidewall of the etching film 2, and at the same time, the process layer 3 and the etching film 2 are etched by a chemical reaction caused by a large ion collision in a horizontal plane having a high ion collision probability. And anisotropic etching is performed by forming a polymer film (4) on the surface of the process layer (3). 2. The polymer film (4) according to claim 1, wherein the polymer film (4) is formed by the formation of the polymer film (4) according to the gas by plasma discharge, by recombination due to the formation of an unsaturated radocal of the gas, and by the ion collision in the horizontal plane. Anisotropic etch method by forming a polymer film, characterized in that formed by recombination of by-products and gas. The method of claim 1, wherein the etching film (2) uses BCl ₃ + SF ₆ + N ₂ gas for etching of MoSix, NiN, TiW, WSix, and the like. The method of claim 1, wherein the plasma is formed using a microwave source. The anisotropic etch method according to claim 4, wherein the etching gas is Cl ₂ or Cl ₂ + O ₂ gas when the etching film is polysilicon. The method of claim 1, wherein when the etching film (2) is MoSix, BCl ₃ + N ₂ + SF ₆ is used as the plasma reaction gas.