JPS60102745A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To etch a polysilicon film at high speed with excellent controllability by using a mixed gas of a CXClYFZ group (X, Y, Z represent integers) and oxygen O2 for etching the polysilicon film. CONSTITUTION:A mixed gas of C2ClF5 and oxygen O2 is introduced to an etching device proper 2, to which electrodes 4, 5 are arranged, from an etching gas introducing port 6, and a polysilicon film 2 is etched at etching pressure of 0.8Torr. When the polysilicon film is etched at 20% oxygen concentration and an electrode space of 40mm., the film is etched as shown in the figure (a) on a just etching and as shown in the figure (b) on an over-etching of 100%, and a side etching does not progress even on an over-etching.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a method for manufacturing a semiconductor device, and more particularly to an improvement in a method for etching a polysilicon film during the manufacturing of a semiconductor device.

[Prior art]

FIGS. 1 and 2 show the state during etching of a polysilicon film in a conventional manufacturing method of this type of semiconductor device. That is, in each of these figures, reference numeral 1 indicates a semiconductor substrate, 2 indicates a polysilicon film formed on this semiconductor substrate 1 as a film to be etched, and 3 indicates a patterned silicon film covering this polysilicon film 2. This is an etching mask such as a photoresist film.

However, the above-mentioned FIG. 1 shows a cross section of the main part when etching is performed using CF4+O2 and the etching is terminated at the moment the surface of the substrate 1 is exposed, and the above-mentioned FIG.
2 is a cross section of a main part when etching is performed for a time 2t, which is twice the time t required for the surface of the substrate 1 to be exposed.

As is clear from these figures, since the above-mentioned CF4+O2 gas is used for etching a polysilicon film in the conventional method, the etching rate is limited to about 3,000 A/min at most. However, the amount of side etching is large and dimensional control is difficult.

[Summary of the invention]

In view of these conventional drawbacks, the present invention uses a mixed gas of CXCtYF z 102 for etching a polysilicon film, thereby making it possible to perform etching at high speed and with good controllability.

[Embodiments of the invention]

3, FIG. 4(a) + (b), and FIG. 5(,
), (C) and FIGS. 6(a) and 6(d).

FIG. 3 shows an example of an etching apparatus applied to this embodiment method. In this FIG. 3, numeral 4 indicates the main body of the device;
Reference numerals 5 and 6 denote a pair of electrodes arranged in the main body 4 of the apparatus, I an etching gas inlet, 8 an etching gas outlet, and 9 an oscillator of, for example, 13.56 MHz as a power source.

However, in this etching device, C2ctF s +02
Etching pressure: 0.8 Torr
r.

Figures 4 (a), (b) to 6 (a) show the state when polysilicon film is etched with fixed RF power.
It is shown in (b). In each of these figures, the first
The same reference numerals as those in the figures and FIG. 2 indicate the same or corresponding parts.

FIG. 4 (JL) l (b) is an example in which etching is performed at an 02 concentration of 20% and an electrode spacing of 40, and the etching rate is approximately 6,000 A/min, which is twice the conventional etching rate. The same figure (,) shows the cross section when just etching, and the same figure (b) shows the cross section when 100 th.
It can be seen that even when thiover etching is performed, side etching does not proceed as in the conventional method, and that the method is excellent in terms of dimensional control.

FIG. 5 (IL) shows an example in which etching is performed at a 0□ concentration of 20%, and FIG. 5(c) shows an example in which etching is performed at an O2 concentration of 35 cm and an electrode spacing of 40 mm. The etching rate is about 1 .mu.m/mln in FIG. 1(c), which is three times that of the conventional method, and the etching cross section is also tapered as indicated by the symbol e.

Figure 6 (,) shows 02 concentration of 20% and electrode spacing of 40 mm.

Figure (d) is an example of etching performed at a 02 concentration of 20 cm and an electrode spacing of 5 mm. In FIG. 3(d), the cross-section of the Tefer etching is formed in a reverse tapered shape as indicated by the symbol f.

That is, as is clear from these figures, when using the method of this embodiment, it is possible to obtain an etching rate of up to 1 μm/miH, and the amount of side etching is also small, resulting in excellent dimensional controllability. By changing the 02 concentration or the electrode spacing, the taper angle of the etched cross section can also be controlled.

In the above embodiment, C2C was used as the etching gas.
tF5+0□ was used, but other Cxc#Fz systems (
Similar actions and effects can be obtained by combining x, y, z: natural numbers) and 02.

〔Effect of the invention〕

As detailed above, when using the method of the present invention, CX is used for etching a polysilicon film when manufacturing a semiconductor device.
By using a mixed gas of CtYFz series (x, y, z: natural numbers) and 02, the same etching film can be etched at high speed and with good dimensional control using the same etching equipment as before.
It can be etched effectively under cross-sectional shape control, and its processing performance and capacity can be improved.

[Brief explanation of drawings]

1 and 2 are cross-sectional views showing the state during etching of a polysilicon film in a conventional semiconductor device manufacturing method, FIG. 3 is a cross-sectional view schematically showing an example of the configuration of an etching apparatus, and FIG. (a), (b) to Figure 6 (
') l (b) is a sectional view showing the state during etching of a polysilicon film using the same apparatus as described above according to an embodiment of the method of the present invention. 1... Semiconductor substrate, 2... Polysilicon film, 3
...Fist/etching mask, 4...O etching device body, 5, 6...1 set of electrodes, 7.8...Gas introduction, exhaust port, S...-oscillator. Agent Masuo Oiwa

Claims (1)

[Claims] In a method of manufacturing a semiconductor device in which a polysilicon film formed on a semiconductor substrate is masked and the polysilicon film is etched with an etching gas, the etching gas contains CXC4YFZ (x, y
, z: natural number) and 02.