JPS5846638A - Reactive ion etching device - Google Patents

Abstract

PURPOSE:To enable the reactive ion etching device which generates no residue and shapes a pattern having high accuracy by forming an opening section by a concave section or a through port to an electrode at the ground side, giving plasma discharge a hollow effect and improving the degree of dissociation. CONSTITUTION:A cathode 2 is fitted to a reaction vessel 1 grounded, and a high-frequency power supply 3 in 13.56MHz is connected through a matching circuit 4. An anode 5 oppositely forming parallel plate electrodes is grounded, and a workpiece 7 is placed onto a carbon board 6 on the surface of the cathode 2. The cathode 2 or the anode 5 is turned during etching in order to obtain the uniformity of a wafer. The anode 5 has a 50cm diameter, and the concave section 5' having a 6mm. diameter and 12mm. depth is shaped at the center. When the total flow rates of CF3Br and Cl2 are made 30SOCM and a phosphorus doped poly-Si film formed onto the silicon wafer 20 in the figure a through CVD through a thermal silicon oxide film 21 under the states of a 60% Cl2 flow rate ratio, 0.1 Torr total pressure and 0.3w/cm<3> high-frequency power is etched while using a photo-resist as a mask, an etching profile in which there is no residue and undercut in the figure b is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a reactive ion etching apparatus used for forming patterns of semiconductor devices and the like.゛In recent years, methods of forming patterns using reactive ions have attracted attention in the manufacturing process of semiconductor devices, especially LSIs and ultra-L8Is41}κ
Research and development is also being carried out on the device itself for forming highly accurate patterns. Among these methods, there is a method in which high-frequency power is applied to an electrode on which the material to be patterned is placed, thereby introducing the reactive gas into the processing chamber and causing a glow discharge (also referred to as low-temperature plasma discharge) of a reactive gas at zero pressure. At this time, the potentials of the high-frequency electrode are adjacent to each other, resulting in a negative self-bias, based on the difference in mobility between electrons and ions caused by plasma discharge. This negative self-bias is called a base voltage drop, is measured from the ground potential, and is expressed as Vdc, and varies depending on the shape of the electrodes of the device, etc.

The positive ions in the plasma, which is an etchant, are
It accelerates and irradiates the area to be etched, reacts with the irradiation, becomes gasified, and is exhausted out of the system.

1 shows a cross-sectional view of a conventionally used reactive ion etching apparatus. The etching apparatus reaction vessel (1) is provided with a frequency electrode, hereinafter referred to as an anode (2).

This cathode {2} is connected to a 13.56MHz high frequency power source (3
) are connected via a matching circuit (4). A grounded anode (5) is provided opposite to the above-mentioned electrode (2) so as to form a parallel plate electrode. A carbon plate (6) is placed on the surface of the cathode (2), and the object to be etched is placed on top of the carbon plate (6). By applying high-frequency power to the anode (2) while expelling the reactive gas from the gas outlet (8) provided in the reactor (1) and exhausting it from the exhaust port (9).
A uniform glow discharge (plasma discharge) (11) is generated and reactive ions/nip/g is performed.

When etching silicon oxide (SiOx) to form a contact hole, good etching can be achieved by using CF4+)I, CHF.

Single crystal silicon (Si) and polycrystalline silicon (poly
-S i) poly -8i with especially added impurities
other materials, such as 810. Although it was difficult to perform etching with good pattern accuracy and high etching selectivity, these problems were solved to some extent by using CBrF C1 gas.

However, etching residues peculiar to poly-8i, especially poly-Si to which impurities such as phosphorus (P) are added, sometimes occur, and in order to remove them, Cj
The reduction in flexibility was achieved by increasing the m flow rate ratio, but the new K
For this reason, in order to maintain machining accuracy, a small amount of etching residue has been sacrificed, but in recent years, the density of elements seen in LSI devices has increased. However, even small amounts of etching residue can cause electron defects, which has become a major problem.

The present invention was developed in consideration of the above circumstances, and after extensive research, it was discovered that the poly-8i etching residue in the reactive ion nip puffer is related to the plasma discharge behavior caused by the structure of the etching device. , a parallel plate electrode with a grounded 1iIl electrode has an opening S formed by a recess or a through hole, which gives a hollow effect to the plasma discharge and improves the degree of dissociation, resulting in poly-8I that does not generate any residue. The object of the present invention is to provide a reactive ion etching device that enables highly accurate pattern formation.

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

@211 shows an embodiment of the present invention, in which a reaction vessel +1) is provided with a cathode (2) and connected to a 13.56 MHz high frequency power source (3) via a matching circuit (4). Anodes (5) facing each other forming parallel plate electrodes are grounded, and a carbon plate (6) is placed on the surface of the cathode (2), on which a workpiece is placed. On the other hand, the container (1) is also grounded. The cathode (2) is rotated within the wafer during etching to obtain rounding uniformity. The anode (5) may also be rotated. (8) is a gas inlet, (9) is an exhaust port, and Uυ is a refrigerant pipe.

The anode (5) is a 501 pole, and a recess (5) with a diameter of 16E, 6 inches and a depth of 12 inches is provided in the center.

Here, add 3r to Ck'@ and the total flow rate of (j) to 30110
0M, Cjffi flow rate ratio 60 pm, total pressure Q, ITo
A phosphorus-doped poly-8+ film (60°
00λ thickness) using a 7-photoresist as a mask, an etching profile without residue or undercut can be obtained as shown in FIG. 3(b).

Figure 3 (C) shows a total flow rate of 30aOOM and a C'wa amount ratio of 6.
0%.

0.1Torr, 0.3w/d TE, conventional TAFL
It is a sectional view taken by K yb machining y f /f. Although there was no undercut, columnar *dl@ was generated.

Also, Fig. 3(d) shows the same <C12 flow rate ratio 8 at conventional fj position.
Figure 3 (
Although the residue (2) of C) is not visible, an undergoo cut (2) in a reverse tapered shape is formed.

In Figure 3 (-, the workpiece is a 4-inch wafer;
Cathode (2) arranged in a circle at a position of 201 from the center;
By providing the recess in the anode (5) in this manner, a hollow effect is generated, the degree of plasma dissociation is increased, and the generation of residue can be prevented. There is no need for a recess to be provided at the center of the recessed Fi anode (5), but it may be provided at the opposing portion of the wafer.

Also, as a substitute for CFiBr and C1, CFIBr + fi
Similarly good results were obtained when using r.

In the above embodiment, one recess is provided in the ground electrode, but nine examples are described. However, depending on the size of the reaction chamber and the area and quantity of the objects to be etched, a large number of recesses may be provided, and the ground electrode may be provided with one recess. The present invention was also effective in a nine reaction apparatus in which the opening was vacuum sealed. Needless to say, similar results were obtained when several through holes were provided in this case.

Further, as a modification of the present invention, the shape of the ten portions of the recess or through-hole is not limited to a circular shape, but may be shaped as shown in FIGS. 3(a) to 3(e).

D, ≦D for the opening diameter D+Fi and Dl toward the center of the opening.

It is preferable to have the following relationship in order to improve the degree of dissociation, and the Sekiguchi may be provided anywhere on the #i pole, but the number that is 50D and ≦D3 with respect to the diameter D3 of the parallel plate electrode matrix prevents uneven etching. Good for what you do.

In addition, the opening can also serve as a gas inlet to achieve the same result and to further prevent the occurrence of cruelty, but in addition to carbon plates, hydrocarbon-based organic films such as polyester films or polypropylene may be used.

Polymer films such as isopolypropylene and polystyrene may be used, and sheets containing carbon are effective.

In practical use, CF4. C, F・etc.C-
It is even better to deposit a Teflon-based polymer film over the entire anode by adding Hl to the F gas and subjecting the gas to plasma discharge in advance. This polymer membrane is indicated by the number α in FIG.

As explained above, the present invention is effective in preventing etching residues, and is effective in preventing etching residues formed on monocrystalline silicon, polycrystalline silicon, amorphous silicon, and silicon substrates.
, W, etc. are effective for etching high-melting point metals used for electrode wiring or their high-melting point metal silicides, especially those to which impurities are added, and CFIBr is used as a reactive gas.
+(j,) and others, CF'sBr+Srt, OF, ij
r +I, , CF, CI-+ Mrt, CF, C
j+CJ, , CF, Cj+I,.

OF@l-41r,, (J, l-4-(j!, CF
, I+I, and even CF, 8r 1CBr,, 011
Even if a partner is used, the effects of the present invention do not change.

[Brief explanation of the drawings] Figure 1 is a # side view of a conventional reactive ion etching device.
#I2 is a cross-sectional view of the reactive ion etching device used in the embodiment of the present invention, Figure 3 is a cross-sectional view explaining the details of the present invention, and Figure 4 is a recessed portion of the J formed by this invention. Or it is a top view of a penetration hole. In the figure, 1... reaction container, 2... cathode, 3...
High Mll wave power supply, 4... Matching box, 5... Ground electrode, 5... Recessed part, 6
...Carbon plate, 7...Workpiece intelligence, 8...
・Gas inlet, 9...exhaust port, lO...
Plasma discharge, lO...Hollow effect, 11...Refrigerant pipe, 12...Insulating material, 13...Polymer membrane, 14...Dark space seal)' (M edge body) , Canada
...Silicon substrate, 4...Silicon oxide film, 4
...Polycrystalline silicon, Mu...Photoresist. Representative Patent Attorney Yu Yu Chika and 1 other person Figure 1 Figure 2 Figure 3 Figure 4-19';

Claims (2)

[Claims] (1) Polarize the parallel plate VL1 consisting of nine anodes arranged opposite to each other and an anode to which high-frequency power is applied;
In a reactive ion etching device in which a workpiece is placed on the anode to which high-frequency power is applied and plasma is generated between the electrodes, a recess or a through hole is provided in the anode surface facing the anode, and the anode or A reactive ion etching device in which at least one of the anodes is rotatable. (2) Opening diameter Dh of the recess or through hole - Depth of the opening DI
+Parallel plate electrode diameter Ds is ≦Bird, 50D+≦L)
A patented reactive ion etching device characterized by: