JPH0922882A - Formation of contact hole of minute semiconductor element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the damage of a lower insulation layer and insulation between undesired conductors against the side wall of a contact hole when an insulation spacer is formed in a fine contact hole by forming an insulation film for forming a spacer in a manner to weaken its covering characteristic of stepped part and forming an insulation spacer through anisotropic etching thereafter. SOLUTION: An oxide film 24 for forming a spacer is made relatively thick on an insulation film 22, while it is made reatively thin on the side wall of the film 22 in a contact hole and in the area connecting with an active region 20 on a silicon substrate 21 or conductive parts of other devices. The film 24 is anisotropically etched until the region 20 in the contact hole is exposed thoroughly to a blanket. Thus, in the interior of the contact hole, an insulation spacer 24" is prepared, and the devices and conductors protected by the film 22 can be prevented from being connected undesirably with the side wall of the contact hole even in the following steps such as vapor depositing of conductor, etc., for contact formation.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of forming a contact hole during a semiconductor device manufacturing process, and more particularly to a fine semiconductor device for preventing a lower insulating layer from being damaged when an insulating spacer is formed in the fine contact hole. The present invention relates to a contact hole forming method.

[0002]

2. Description of the Related Art Contact holes are becoming more and more difficult to form due to the increased integration of semiconductor devices. As a result, a contact hole having the first largest width is formed in order to form a fine contact hole by opening (opening) only a connecting portion while effectively maintaining insulation between the inner conductors. A method of forming an insulating spacer on a sidewall to prevent a short circuit between conductors due to a contact hole is widely used.

3 (a) and 3 (b) are sectional views showing a process of forming a contact hole by a conventional method, and the conventional technique will be schematically considered through the following steps.

In FIG. 3A, an insulating film 12 is formed after forming other elements and wiring (not shown) on the silicon substrate 11. After this, photolithography
A contact hole mask is formed through a photolithography process and is used as an etching mask to remove the insulating film 12 in a portion connected to the device and the wiring by an anisotropic dry etching method, thereby forming the active region 10 already formed. FIG. 6 is a cross-sectional view showing a state in which the photoresist is removed after exposing the film, and a spacer forming oxide film 13 is deposited.

Next, as shown in FIG. 3B, the spacer forming oxide film 13 is anisotropically etched on the blanket until the active region 10 inside the contact hole is completely exposed, and the insulating spacer 13 is formed. In the cross-sectional view of the state where'is formed, reference numeral 12 'in FIG. 3B indicates that a part of the insulating film 12 during etching for forming the spacer is damaged.

[0006]

However, in the above-mentioned conventional method, the lower insulating film is etched in the required excessive etching process when the insulating spacer in the contact hole is formed. As a result, there is a great concern that an undesired connection between the conductors may occur during a subsequent process for forming the contact.

Therefore, the present invention devised to solve the above-mentioned problems of the prior art is intended to prevent the lower insulating layer from being damaged during the formation of the insulating spacer in the fine contact hole. It is an object of the present invention to provide a method for forming a contact hole in a semiconductor device.

[0008]

In order to achieve the above object, the present invention provides a method of forming a contact hole of a semiconductor element, the step of supplying a semiconductor substrate, and forming a first insulating film on the semiconductor substrate. A step of removing a predetermined portion of the first insulating film to form an opening exposing the semiconductor substrate, and forming a second insulating film on the upper portion of the entire structure, which is formed on a sidewall of the opening. Forming the second insulating film having a thickness smaller than that of the second insulating film formed on the first insulating film, and the second insulating film so that a predetermined portion of the semiconductor substrate is exposed. And anisotropically etching the film to form an insulating film spacer on the sidewall of the opening.

In order to achieve the above object, the present invention provides a method for forming a contact hole in a semiconductor device,
A step of supplying a semiconductor substrate, and a first step on the semiconductor substrate.
Forming an insulating film; forming a second insulating film having a uniform thickness on the first insulating film; and removing a predetermined portion of the first and second insulating films to expose the semiconductor substrate. A step of forming an opening that allows the third insulating film to have a uniform thickness on the entire structure, and the third insulating film is anisotropic so that a predetermined portion of the semiconductor substrate is exposed. And forming an insulating film spacer on the side wall of the opening by erosion etching.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described in detail with reference to the attached FIGS. FIG. 1 (a) (b)
1A is a cross-sectional view showing a process of forming a contact hole according to an embodiment of the present invention. First, as shown in FIG. 1A, after forming other elements and wiring not shown on a silicon substrate 21, an insulating film 22 is formed. A contact hole that is formed and is formed in a subsequent process is insulated from an element and a wiring that are already formed and connected through the contact hole.

Subsequently, photolithography (photo
After forming the contact hole mask through the lithography process, the insulating film 22 of the portion connected to the device and the wiring is removed by the anisotropic dry etching method using the contact hole mask as an etching mask, thereby forming the already formed active region. Expose 20. At this time, the insulating film 22 is a normal oxide film, or BPSG (borophosphosilicate).
e-glass) film, PSG (phosphosili)
Cate glass) film or a combination of the oxide films listed above.

Next, the photoresist is removed by a usual plasma photoresist etching method and a wet photoresist etching method, and a spacer forming oxide film 24 is deposited.
At this time, the spacer forming oxide film 24 is relatively thick on the insulating film 22 and is connected to the sidewall of the insulating film 22 in the contact hole and the active region 20 of the silicon substrate 21 or the conductor portion of another element. Then, make it relatively thin.

As shown in Table 1 below, the spacer forming insulating film 24 is formed by LTO (Low Temperature O) by a separate vapor deposition process having different process conditions.
xide), MTO (Middle Temperat)
er Oxide), LPTEOS (Low Pre)
ssure TEOS (tetraethoxysila)
ne)) each oxide film can be formed.

[0014]

[Table 1]

However, TEOS represents Si (OC ₂ H ₅ ) ₄ .

Next, as shown in FIG. 1B, the spacer forming oxide film 24 is anisotropically etched by blanket until the active region 20 inside the contact hole is completely exposed. At this time, even if a part of the spacer oxide film 24 ′ is left on the insulating film 22 or the lower insulating film 22 is etched, the thickness of the insulating film consumed is very small. The protected element and conductor are not exposed, and the insulating film 22 having a sufficient thickness provides an insulating state. Also, the inside of the contact hole is the insulating spacer 2.
By 4 ", it is possible to prevent undesired connection of the element and the conductor protected by the insulating film 22 to the side wall of the contact hole even in the subsequent step such as vapor deposition of a conductor for forming a contact.

On the other hand, FIGS. 2A and 2B are sectional views showing a process of forming a contact hole according to another embodiment of the present invention. First, as shown in FIG.
Other elements and wiring not shown are formed. After that, an insulating film 32 is formed, an oxide film 35 is formed on the insulating film 32, and then photolithography (photo) is performed.
A contact hole mask is formed through an o-lithography process and is used as an etching mask to remove the insulating film 32 and the oxide film 35 in a portion connected to the device and the wiring by an anisotropic dry etching method. A contact hole is formed to expose the exposed active region 30. At this time, the insulating film 32 is an ordinary oxide film, a BPSG film,
It is produced by a combination of the PSG film or the oxide films listed above.

Next, the photoresist is removed by the usual plasma photoresist etching method and wet photoresist etching method, and the spacer forming oxide film 36 having a uniform thickness is deposited under the following process conditions.

Temperature: 800 to 950 ° C. Pressure: 0.1 to 4.0 Torr Source gas: SiH ₂ Cl ₂ (dichloros, la)
ne) + N ₂ O gas amount: 60 sccm: 60 sccm gas ratio: 1:10 At this time, by forming an oxide film on the insulating film 32, the insulating layer is relatively relatively formed on the insulating film 32 as a whole. The side wall of the insulating film 32 in the contact hole is thick and is relatively thin in the portion connected to the active region 30 of the silicon substrate 31 or the conductor portion of another element.

Next, as shown in FIG. 2B, the spacer forming oxide film 36 and the oxide film 35 are etched by an anisotropic etching method to form an insulating spacer 36 '. At this time, a part 35 'of the oxide film 35 remains on the upper portion of the insulating film 32, and the lower insulating film 32 is protected by the lossless residual oxide film 35'. Also, the inside of the contact hole is prevented by the insulating spacer 36 'from causing an undesired connection between the element and the conductor protected by the insulating film 32 on the side wall of the contact hole even in a subsequent step such as vapor deposition of a conductor for forming a contact. You can do it.

In the present invention configured as described above,
The spacer forming insulating films 24 and 36 are covered with the step portion covering characteristic (s
The insulating spacers 24 ″ and 36 ′ are formed by anisotropic etching after forming the insulating layer to be fragile, so that the lower insulating layer is prevented from being damaged in forming the insulating spacer in the fine contact hole. Further, it is possible to prevent undesired connection between conductors on the side wall of the contact hole.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a process of forming a contact hole according to an embodiment of the present invention.

FIG. 2 is a sectional view showing a process of forming a contact hole according to another embodiment of the present invention.

FIG. 3 is a cross-sectional view showing a process of forming a contact hole by a conventional method.

[Explanation of symbols]

10 ... Active region, 21, 31 ... Silicon substrate, 22, 3
2 ... Insulating film, 24, 36 ... Spacer forming oxide film, 2
4 "... Insulating spacer, 35 ... Oxide film, 36 '... Insulating spacer.

Front Page Continuation (72) Inventor Bak Sung Wook South Korea 467-860 Kyung Kidd Yi Yong Kun Buba Ryu Ami Risan 136-1 Hyundai Electronics Industry Co., Ltd. Limited

Claims (8)

[Claims] 1. A method of forming a contact hole in a semiconductor device, comprising: supplying a semiconductor substrate; forming a first insulating film on the semiconductor substrate; and removing a predetermined portion of the first insulating film. Forming an opening exposing the semiconductor substrate; and forming a second insulating film on the upper portion of the entire structure, wherein the thickness of the second insulating film formed on the sidewall of the opening is the first insulating film. Forming the second insulating film to a thickness smaller than that of the second insulating film formed thereon, and forming the second insulating film so that a predetermined portion of the semiconductor substrate is exposed.
And a step of forming an insulating film spacer on the sidewall of the opening by anisotropically etching the insulating film. 2. The method of forming a contact hole in a fine semiconductor device according to claim 1, wherein the second insulating film is formed at 0.1 to 4.0 Torr. Method. 3. The method of forming a contact hole of a fine semiconductor device according to claim 2, further comprising the step of forming the second insulating film at 300 to 500 ° C. using SiH ₄ and O ₂ gas. A method for forming a contact hole in a featured fine semiconductor device. 4. The method for forming a contact hole of a fine semiconductor device according to claim 2, further comprising the step of forming the second insulating film at 700 to 900 ° C. using SiH ₄ and N ₂ O gas. A method for forming a contact hole in a fine semiconductor device, comprising: 5. The method for forming a contact hole in a fine semiconductor device according to claim 2, wherein the second insulating film is formed of Si.
600-800 using (OC ₂ H ₅ ) ₄ and N ₂ O gas
A method of forming a contact hole in a fine semiconductor device, comprising the step of forming the contact hole at a temperature of ° C. 6. A method of forming a contact hole in a semiconductor device, comprising: supplying a semiconductor substrate; forming a first insulating film on the semiconductor substrate; and forming a first insulating film on the first insulating film with a uniform thickness. A step of forming a second insulating film, a step of removing predetermined portions of the first and second insulating films to form an opening exposing the semiconductor substrate, and a third step of forming a uniform thickness on the entire structure. Forming an insulating film; and anisotropically etching the third insulating film until a predetermined portion of the semiconductor substrate is exposed to form an insulating film spacer on a sidewall of the opening. A method for forming a contact hole in a featured fine semiconductor device. 7. The method of forming a contact hole in a fine semiconductor device according to claim 6, wherein the third insulating film is formed at 0.1 to 4.0 Torr. Method. 8. The method of forming a contact hole of a fine semiconductor device according to claim 7, wherein the third insulating film is formed by using SiH ₂ Cl ₂ and N ₂ O gas at 800 to 950.
A method of forming a contact hole in a fine semiconductor device, comprising the step of forming the contact hole at a temperature of ° C.