JPH01255664A - Formation of thin film - Google Patents

Abstract

PURPOSE:To form a thin film on a specimen without lowering step coverage and evenness while making damage affecting an element small by especially making both reactive gas added with etching gas and sputtering gas to plasma with plasma discharge and producing the excitation species. CONSTITUTION:A magnetic field is generated in plasma chamber 7 by electrifying a magnetic coil 3 and microwaves are introduced 8 into the chamber 7. Simultaneously SiH4, etc., as a feed source incorporated in reactive gas, O2 and H2O, etc., as an O2 feed source incorporated therein, gaseous Ar as sputtering gas and furthermore SF6 and CF4, etc., as etching gas are introduced into the chamber 7 respectively. As a result, SiH4 and O2, etc., are dissociated by plasma discharge to generate the excitation species such as ions and radicals. A thin film is formed on a base plate (specimen) 2 by allowing these excitation species to react and also negative auto-bias is induced by impressing RF high frequency on a specimen base 1 with a high frequency power source 5 and directional property is given to the plasma flow and a thin film excellent in step coverage and evenness is formed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to electron cyclotron resonance (E 1 ectron resonance).
Cyclotron Re5onance) excited plasma or RF (Radio Frequency)
) Using excited plasma・CV D (Ckmical
The present invention relates to a thin film forming method using a vapor deposition method, a sputtering method, or the like.

[Conventional technology]

Improvements in photolithography technology, reactive ion etching technology, etc. have made it possible to manufacture VLSIs using CVD methods that utilize plasma discharge, sputtering methods, and the like.

When forming a thin film on a sample such as a silicon substrate by CVD or sputtering, in order to improve the step coverage or flatness of the thin film, it is necessary to use a support stand on which the sample is placed. One of the improved techniques is to apply a high frequency to induce self-bias.

[Problem to be solved by the invention]

However, when self-bias is induced in the support, there is a problem that the sample itself is damaged by the sputtering gas during the planarization process. This problem can be solved by lowering the self-bias voltage, but this results in a decrease in step coverage and flatness. Also, the t that the element receives
Even when the amount of sputtering gas used is reduced in order to reduce damage, the step coverage and flatness are similarly reduced.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a three-layer forming method that does not reduce step coverage and flatness and can reduce damage to elements. .

[Means to solve the problem]

The present invention has been made to achieve the above-mentioned object, and the thin film forming method according to the invention described in claim 1 is characterized in that a reactive gas and a sputtering gas are turned into plasma by plasma discharge to generate excited species, and a high frequency wave is generated. A method for forming a thin film in which a thin film is formed on a sample on a support base by applying a self-bias to induce a self-bias, characterized in that an etching gas is added to the reaction gas and the sputtering gas, and the invention according to claim 2 The thin film forming method is a thin film forming method in which a sputtering gas is turned into plasma by plasma discharge to generate excited species, and a thin film is formed on a sample on a support base on which a self-bias is induced by applying a high frequency. A feature of this method is that an etching gas is added to the gas.

[Effect]

Exciting sputtering and etching gases or reactive gases, sputtering gases, and etching gases by plasma discharge generates excited species. A thin film is formed on the sample by the reactive species, and a self-bias is induced by applying high frequency to the support base on which the sample is placed, and the excited species of the sputtering gas and etching gas preferentially form the convex parts of the thin film. By etching, a thin film with excellent step coverage and flatness and less damage is formed on the sample.

〔Example〕

Hereinafter, an embodiment 911 of the present invention will be explained based on the drawings, taking a plasma CVD method as an example.

FIG. 3 shows a plasma CVD apparatus, which itself is a known apparatus. In the figure, 6 is a reaction chamber, and a sample stage 1 on which a sample substrate 2 is placed is placed in the center of the reaction chamber 6 with its placement surface being horizontal.

A plasma extraction window is provided in the upper part of the reaction chamber 6, so that the plasma generated in the plasma chamber 7 located above is introduced into the reaction chamber 6. A microwave introduction window is set up on the upper wall of the plasma chamber 7.
The plasma chamber 7 and a microwave oscillation source (not shown) are connected via a waveguide 8 . Further, a magnetic coil 3 is wound around the plasma chamber 7. On the other hand, sample stage 1
is connected to a high frequency power source 5 via a matching box 4 in order to increase the effective value of the output, so that a self-bias is induced.

In such a plasma device, the magnetic coil 3 is energized to generate a magnetic field in the plasma chamber 7, a microwave oscillation source (not shown) oscillates microwaves, and the microwaves are transmitted to the plasma chamber 7 via a waveguide 8. At the same time, SiH4, 5iJ6, etc. are introduced into the plasma chamber 7 through an inlet (not shown) as a silicon supply source among the reaction gases, 0□, HzO, COt, etc. as an oxygen supply source among the reaction gases, and a sputtering gas is also introduced into the plasma chamber 7. In addition, SFb, CF4, CHF4, etc. are added to the plasma chamber 7 as an etching gas.
to be introduced.

Then, SiH4,0□, etc. are dissociated by plasma discharge, and excited species such as ions and radicals are generated, and these excited species react to form a thin film on the substrate.
RF high frequency (13, 56
When a negative self-bias is induced by applying a negative self-bias (MHz), directionality is generated in the plasma flow, and a thin film with excellent step coverage and flatness is formed. Further, the convex portions of the thin film formed by the excited species of the sputtering gas and the etching gas are preferentially sputtered and etched. In addition, in this example, microwave energy of 800 (b)
, RF energy 300 (b) was used.

Figure 2 shows a case where a thin film is formed on a substrate using such an apparatus, and SF4 is not added (indicated by ◇ in the figure).
, SF, flow rate is 10 (SCCM > (○ in the figure)
Indicated by ) and SF, the flow rate is 20 (SCCM) (
Indicated by Δ in the figure. ) The relationship between the metered gas flow rate and the flatness in each case is shown with the Ar gas flow rate (SCCM) on the horizontal axis and the value obtained by dividing the sidewall recession rate by the film formation rate on the vertical axis. be. Here, the sidewall retraction speed is the value obtained by dividing the sidewall retraction distance d by the film forming time t, as shown in the conceptual diagram in FIG. This is the distance from the peripheral edge of the thin film on the pattern to the peripheral edge of 〇. In this way, the flatness can be expressed as the value obtained by dividing the sidewall receding speed by the film deposition rate.As is clear from FIG. is expressed as d/T, and dividing this denominator and numerator results in (
d/l)/(T/l), which is equal to the sidewall recession rate divided by the film formation rate.

As is clear from Figure 3, A: If the gas flow rate is constant, the flatness of the thin film is better when using SF than when not using SF6, and the higher the SP&flow rate, the better the flatness of the thin film is. In addition, when SF is used, compared to when SF is not used, a smaller amount of Ar gas flow rate is required to obtain a thin film with the same level of flatness, which reduces damage to the element due to Ar gas. be able to.

〔Effect of the invention〕

In the thin film forming method of the present invention, since an etching gas is added, the step coverage and flatness are excellent, and since relatively low RF power can be used, there is less damage caused by Ar gas. A thin film can be formed on the substrate.

[Brief explanation of the drawing]

Figure 1 is a flatness graph, Figure 2 is an explanatory diagram of flatness, and Figure 3 is a flatness graph.
The figure is an explanatory diagram of a bias type plasma cV6 device. 1...Support stand 2...Sample 6...Reaction chamber 7...
・Plasma chamber 8...Waveguide time Applicant Sumitomo Metal Industries Co., Ltd. Agent Patent attorney Noboru Kono OTo 20 30
40 5OA, use X (SCCM) Winnow 1 Kokukan 2 Concave chopsticks 3 Flash

Claims (1)

[Claims] 1. A method for forming a thin film, in which a reactive gas and a sputtering gas are turned into plasma by plasma discharge to generate excited species, and a thin film is formed on a sample on a support base on which self-bias is induced by applying high frequency waves. A thin film forming method characterized in that an etching gas is added to the reaction gas and the sputtering gas. 2. Generate excited species by turning the sputtering gas into plasma by plasma discharge, use the excited species to launch reactive species from the target by sputtering, and apply high frequency to the sample on the support base to induce self-bias. A thin film forming method for forming a thin film, characterized in that an etching gas is added to the sputtering gas.