JP2000208481A - Collective etching of multilayer different kind insulating film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To carry out etching a multiplayer sample of an organic SOG based insulating film having low permittivity and SiO2 collectively at high rate with good profile. SOLUTION: The ratio of oxygen gas flow rate to etching gas flow rate is set in the range of 0.7-1.3 using a semi-gap parallel plate type UHF band ECR plasma etching system. A gas containing at least any one kind of elements of carbon, fluorine and hydrogen is employed as an etching gas and a gas which can supplying oxygen through dissociation in plasma is employed as an alternative gas of oxygen gas.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an etching method in a manufacturing process of a semiconductor device or the like, and more particularly to a method of collectively dry-etching a laminated structure including different kinds of insulating films.

[0002]

2. Description of the Related Art In recent years, as semiconductor devices have become more highly integrated, finer wiring and more multilayer wiring have been promoted. In a semiconductor device having such a multilayer wiring, the wiring delay is one of the signal delays of the entire device. In order to reduce wiring delay, it is important to reduce wiring resistance and wiring capacitance. In order to reduce the wiring resistance, a damascene process using Cu as a wiring material has been advanced.

On the other hand, p-SiO ₂ having a relative dielectric constant of about ε = 4 has been continuously used as an interlayer insulating film which has a great influence on the wiring capacitance, and the study of a low dielectric constant insulating film has been advanced. Examples of the low dielectric constant film include SiOF, inorganic hydrogen-containing SOG, and organic SOG. The organic SOG mainly handled in the present invention has a structure in which an organic group (mainly a methyl group) is bonded to a side chain with respect to a main chain of —O—Si—O—.

In conventional etching of an interlayer insulating film, specifically, etching of an oxide film such as formation of a contact hole, etching is mainly performed using an organic gas containing fluorine (CHF ₃ or C ₄ F ₈ ). . For fine patterns,
In order to ensure the removability of the pattern bottom, a process of adding a few sccm of oxygen has been established. However, in most cases, the insulating film to be etched is a single type of SiO ₂ .

[0005] As a known example of the conventional etching of a low dielectric constant film, see the monthly Semiconductor World (Semiconducto).
r World) January 1998, page 108. In this conventional example, an organic polymer based low dielectric constant film is mainly taken up.

[0006]

One of the technical problems required for etching when forming a dual damascene structure using a low dielectric constant insulating film is an intermediate stopper layer (for example, SiO ₂ (p-TEOS)). ) And the low dielectric constant insulating film are collectively etched. Conventionally, even with the same insulating film, if the film composition changes, the etching characteristics greatly change, and in many cases, the oxide film etching process conditions must be greatly changed in order to perform optimal etching. Further, even if batch etching can be performed under the same conditions, there is a problem that bowing and sub-trench occur.

SUMMARY OF THE INVENTION An object of the present invention is to overcome the above problems and to provide an insulating film having a low dielectric constant, in particular, organic S
An object of the present invention is to simultaneously etch a OG-based insulating film and SiO ₂ at a high etching rate with good shape.

[0008]

According to the present invention, as a means for solving the above-mentioned problems, a ratio of an oxygen gas flow rate to an etching gas flow rate in a batch etching of a heterogeneous interlayer insulating film is in a range of 0.7 to 1.3. Inside. As another solution, a gas containing at least one of carbon, fluorine, and hydrogen is used as an etching gas.

In the above structure, a gas capable of supplying oxygen by dissociation in plasma is used as a gas instead of oxygen gas. Alternatively, the above gas is diluted with Ar, the pressure of the gas used is set to 2 Pa or less, the total flow rate of the gas used is set to 300 sccm or more, etching is performed using a semi-gap parallel plate type UHF band ECR plasma etching apparatus, or the like. Configuration.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A batch etching of a heterogeneous insulating film laminated structure of the present invention is carried out by using a semi-gap parallel plate type UH shown in FIG.
This is performed using an F-band ECR plasma etching apparatus. In this etching apparatus, an evacuated etching chamber 101 is used.
An upper antenna 1 with an etching gas introduced into it and installed
An electromagnetic wave in the UHF band having a frequency of 450 MHz or the like from 02 is radiated and coupled with a magnetic field generated by the coil 103 to form ECR plasma. The equal magnetic field region having a magnetic field intensity of about 160 Gauss for ECR resonance is located in a space between the antenna and the lower electrode 104 at the center of the antenna, and a bowl-shaped shape that crosses the antenna at the periphery is most preferable.

The sample 105 is held on the lower electrode 104 by electrostatic attraction, and heat exchange is performed with a He flow from the back surface to control the sample temperature at the lower electrode set temperature. An RF bias of 800 kHz is applied to the lower electrode, ions in the plasma are drawn into the sample, and the insulating film is etched. The surface of the antenna 102 is a Si shower plate 106, which serves as a gas supply path.
The apparatus is configured such that a high frequency of 3.56 MHz is applied, F is consumed on the antenna surface, and the composition of active species in the plasma can be changed.

The sample used was, as shown in cross section in FIG.
200 nm thick Si ₃ N ₄ 202, 400 nm thick organic SOG 203, 100 nm thick p-T on Si substrate 201
It has a structure in which an EOS 204, an organic SOG 205 having a thickness of 400 nm, a p-TEOS 206 having a thickness of 100 nm, and a resist 207 having a thickness of 500 nm are laminated in this order.
A fine hole pattern 208 is formed by a photolithography process, and serves as an etching mask.

FIG. 3 is a schematic diagram of a hole shape formed by actually performing etching. In this example, Ar, C ₄ F ₈ , and O ₂ were used as gases used for etching. The flow rates were 320 sccm for Ar, 15 sccm for C ₄ F ₈ , and O
₂ was 15 sccm. The ratio of the O ₂ flow rate to the C ₄ F ₈ flow rate was appropriately adjusted within a range of 0.7 to 1.3, centering on 1, while maintaining both the processing shape and the etching rate. The pressure was 2 Pa, and the distance between the antenna and the sample was 70 mm.

UHF power is 1400 W, RF power is 1200 W and 13.56 MHz supplied to the antenna
The power of the electromagnetic wave is 400W, the antenna temperature is 30 ° C,
The lower electrode temperature was set to −20 ° C.

FIG. 4 shows the correlation between the etching depth and the etching time under these conditions. It can be seen that each insulating film layer is etched at a constant speed. Also, it can be seen that the microloading is small. The etching rate is 500 nm / min or more, and the selectivity with respect to the Si ₃ N ₄ stopper layer is about 10. When the flow rate of Ar was increased or brought to a low pressure region, the staying time of each active species was shortened, and the tendency of the fine pattern to be removed was improved.

The gas used is C ₂ instead of O _2.
A gas such as O or C ₃ F ₆ O for dissociating in plasma to supply oxygen may be used, or may be supplied together with O ₂ . However, in this case, it goes without saying that the preferable flow rate ratio with the etching gas changes. As the etching gas itself, a gas such as CHF ₃ or C ₅ F ₈ can be appropriately used.

[0017]

According to the present invention, it is possible to perform a batch etching of a laminated insulating film, to form a dual damascene structure, in particular, to suppress the occurrence of bowing and sub-trench in through hole processing, and to perform the processing accurately and at high speed. Become.

[Brief description of the drawings]

FIG. 1 is a sectional view of an etching apparatus for implementing the present invention.

FIG. 2 is a cross-sectional view of a typical heterogeneous insulating film stack structure used for etching.

FIG. 3 is a sectional view of a hole-etched shape.

FIG. 4 is a measurement diagram showing a correlation between an etching depth and an etching time.

[Explanation of symbols]

101: etching chamber, 102: antenna, 103: coil, 104: lower electrode, 105: sample, 106: Si
Shower plate, 201: sample, 202: Si ₃ N ₄ ,
203 ... organic SOG, 204 ... p-TEOS, 205 ...
Organic SOG, 206: p-TEOS, 207: resist, 208: hole pattern, 301: processed hole shape.

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Tsuyoshi Yoshida 4-term, Kanda Surugadai, Chiyoda-ku, Tokyo F-term in Hitachi Techno Engineering Co., Ltd. 5F004 AA16 BA04 BA08 BA09 BA14 BB11 BB13 BB18 BB25 BB26 DA00 DA16 DA23 DA26 DB03 DB23 EB01 EB03 5F033 MM02 QQ09 QQ10 QQ12 QQ15 QQ37 RR06 RR25 SS04 TT04 WW05 WW06 XX03

Claims (7)

[Claims] 1. A UHF band ECR of a semi-gap parallel plate type.
An etching method, wherein a ratio of an oxygen gas flow rate to an etching gas flow rate is set in a range of 0.7 to 1.3 in batch etching of a heterogeneous interlayer insulating film using a plasma etching apparatus. 2. The etching method according to claim 1, wherein
One of carbon, fluorine and hydrogen as etching gas
An etching method using a gas containing at least one kind of element. 3. The etching method according to claim 1, wherein
An etching method characterized by using a gas capable of supplying oxygen by dissociation in plasma as a gas replacing oxygen gas. 4. The etching method according to claim 1, wherein Ar is diluted. 5. The etching method according to claim 1, wherein the pressure of the gas used is 2 Pa or less. 6. The etching method according to claim 1, wherein the total flow rate of the gas used is 300.
An etching method characterized by being at least sccm. 7. The etching method according to claim 1, wherein the film to be etched has a laminated structure of organic SOG and SiO ₂ .