JPH0513376A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To provide the title manufacturing method capable of manufacturing semiconductor device by a method wherein an oxide film is etched away at high etching selection ratio between the oxide film and a substrate without developing a crystal defect in the substrate. CONSTITUTION:In order to perform the dry etching step in the manufacturing process of LSI, a carbon fluoride gas or Co or NO gas having the carbon fluoride gas and pi coupling represented by a formula of CnF2n+2 or CnF2n (where, n=2-6) is used.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a semiconductor device. More specifically, it relates to a reactive gas used in a dry etching process.

[0002]

2. Description of the Related Art Conventionally, a reactive gas used for dry etching which requires a high selectivity between an oxide film and a substrate is CF.
₄ + H ₂ , CF ₄ + CHF ₃ , CHF ₃ , CHF ₃ + O ₂
Alternatively, CH ₂ F ₂ is known.

[0003]

The reactive gas used in the conventional dry etching process is such that H causes the F withdrawing reaction from the fluorocarbon compound, and the withdrawing reaction proceeds to etch the oxide film and the substrate. The selection ratio can be increased. On the other hand, the following problems occur.

That is, as shown in FIG. 2A, a silicon oxide film 12 is formed on a silicon substrate 11, and a photoresist pattern 13 formed on the silicon oxide film 12 is used as a mask for etching by a dry etching method. (b) and
As shown in (c), CHF ⁺ , CHF ₂ ⁺ gives C, F
The high density defect layer 14 and the deep crystal defect layer 15 due to H are formed. Further, when the above-mentioned crystal defect layer is formed, the contact resistance becomes high or becomes non-ohmic.

As shown in FIG. 2 (e), the contact resistance is reduced by removing the defective layer (dry etching) 17, but the contact resistance is very low.
Since SI has a shallow Xj (junction depth), if the defect layer is deep, leakage occurs. Also, as shown in FIG. 2 (d), Xj
Undercut when removing the defect layer, even if it does not exceed
16 occurs and it is difficult to form wiring in the next process. The present invention has been made to solve the above-mentioned problems, and has a high etching selectivity with respect to an oxide film and a substrate, and it is possible to manufacture a semiconductor device by etching the oxide film without causing crystal defects in the substrate. An object of the present invention is to provide a method of manufacturing a semiconductor device that can be manufactured.

[0006]

According to the present invention, the LS
When performing dry etching in the manufacturing process of I,
Provided is a method for manufacturing a semiconductor device, which comprises using a fluorocarbon gas of the formula: C _n F _{2n + 2} or C _n F _2n (n = 2 to 6) and a CO or NO gas having a π bond. It

In the present invention, C _n F _{2n + 2} or C _n F
_2n (n = 2 to 4) fluorocarbon gas is used. Fluorocarbon gas is a raw material of plasma for dry etching a silicon oxide film formed on a silicon substrate,
Corresponding plasma has a high etching property for silicon oxide and a low etching property for silicon (etching selectivity), and at the same time, crystal defects are generated even when the surface of the silicon substrate is irradiated or enters the silicon single crystal. which do not induce well, C _n F _{2n + 2} or _{C n F 2n (n = 2~6} )
Can be used.

C_nF_{2n + 2}Or C_nF_2n(N = 2-6)
The fluorocarbon gas shown is C₂F ₆, C₃F₈, C_Four
F_Ten, C_FiveF₁₂, C₆F₁₄, C₂F_Four, C₃F₆, C_Four
F₈, C_FiveF_TenAnd C₆F₁₂There is also C₂F
₆, C₃F₈, C_FourF₈, C ₂F_Four, C₃F₆And C_Four
F₈Is a gas at room temperature and requires no vaporizer.
It is preferable because it is easy to handle.

In the present invention, fluorocarbon gas may be used alone, but C having fluorocarbon gas and π bond is used.
O or NO gas may be used. CO or NO gas having a π bond is a raw material of plasma for dry etching a silicon oxide film formed on a silicon substrate, and is mixed with a fluorocarbon gas to perform plasma dry etching. The selectivity (having a high etching property for silicon oxide and a low etching property for silicon) can be enhanced.

Further, the CO or NO gas having a π bond has a high etching selectivity and a low etching property with respect to silicon, and forms a plasma which does not enter the silicon single crystal even when the surface of the silicon substrate is irradiated. You can The ratio of the amount of the fluorocarbon gas to the CO or NO gas having a π bond depends on the fluorocarbon gas to be used, but it is usually 1 to 3 or more. A capacity ratio of about 50 is required.

[0011]

Ions generated from the C _n F _{2n + 2} or C _n F _2n (n = 2 to 4) gas have a large size and do not enter the crystal of the silicon substrate. CO or NO with π bond
As for the gas, CO is CO _{2 and} CO ₂ becomes CO ₂ because SiO is released from SiO ₂ during etching of the oxide film, but SiO ₂ etching progresses, but since there is no O in Si etching, CO becomes a deposition gas and increases the selection ratio.

[0012]

【Example】

Embodiment 1 An embodiment of the present invention will be described with reference to the drawings. As shown in FIG. 1 (a), a film thickness of 0.5 to 1.5 is formed on the silicon substrate 1.
A μm silicon oxide film 2 is formed, and a resist pattern 3 is formed thereon.

Next, as shown in FIG. 1 (b), this substrate is placed in a magnetically enhanced reactive ion etching (MERIE) apparatus, and CO gas and C ₂ F ₆ gas are used as reactive gases in a 1/4 ratio. The silicon oxide film 2 is etched with the resist pattern 3 as a mask using a mixed gas having a volume ratio of. Although the silicon substrate 1 is also slightly etched by etching the silicon oxide film 2, C and F diffused into the silicon substrate show the relationship between the concentration and the depth thereof as shown in FIG.
As shown in, there are few.

In addition, the formation of a crystal defect layer on the silicon substrate is not observed by TEM observation. Example 2 In Example 1, instead of using C ₂ F ₆ gas, C ₄ was used.
The silicon oxide film was etched in the same manner as in Example 1 except that F ₈ gas was used. In the obtained silicon substrate, formation of a crystal defect layer is not observed by TEM observation.

[0015]

According to the present invention, it is possible to provide a semiconductor device manufacturing method capable of manufacturing a semiconductor device by etching an oxide film without generating a crystal defect layer in a silicon substrate.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of a manufacturing process of a semiconductor device manufactured according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram of a manufacturing process of a conventional semiconductor device.

[Explanation of symbols]

 1 Silicon substrate 2 Silicon oxide film 3 Resist pattern

Claims (1)

Claims: 1. When dry etching is performed in the manufacturing process of an LSI, the formula: C _n F _{2n + 2} or C _n F _2n (n =
2-6) The method of manufacturing a semiconductor device, characterized in that the fluorocarbon gas and the CO or NO gas having a π bond are used.