JPH10261628A - Formation of contact hole of semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for forming a contact hole which has superior process reproducibility and has an increased margin for the optimum processing conditions, since a nitride film and a substrate are not damaged either, and which has an increased evenness in etching and therefore increasing yield and the reliability of element operation. SOLUTION: In the formation of a self-aligned contact hole using a nitride film 15 as an etching barrier layer, a mixed gas of percarbon fluorine carbide gas used for an etching of an interlayer insulating film 16 on the nitride film and carbon monoxide gas is used. By this method, a difference in etching selectivity between the oxide film 16 and the nitride film 15 is increased by C dissociated from CO. As a result, the damage to the nitride film 15 is prevented, and the stoppage of etching by O is also prevented.

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 contact hole of a semiconductor device, and more particularly to a method of manufacturing a contact hole of a semiconductor device using a nitride film as a self-aligned contact (SAC) used as an etching stop layer in contact hole etching. Things.

[0002]

2. Description of the Related Art The recent trend of high integration of semiconductor devices has been greatly affected by the development of fine pattern forming technology, and photosensitive films widely used as masks in etching or ion implantation processes in the manufacturing process of semiconductor devices. The miniaturization of the pattern is an essential condition.

[0003] The resolution (R) of the photosensitive film pattern is proportional to the wavelength (λ) of the light source of the reduction exposure apparatus and the process variable (K), and is a numerical aperture (N) of the exposure apparatus.
A, numerical aperture). [R = k * λ / NA, R = resolution, λ = wavelength of light source, N
A = numerical aperture]

Here, the wavelength of the light source is reduced to improve the optical resolution of the reduction exposure apparatus. For example, G-lines and i-lines having wavelengths of 436 and 365 nm are used.
The line reduction exposure apparatus has a process resolution of about 0.7,
The limit is about 0.5 μm. To form a fine pattern of 0.5 μm or less, deep ultraviolet rays having a small wavelength are used.
ra violet; DUV), for example, K having a wavelength of 248 nm.
An exposure apparatus using an rF laser or a 193 nm ArF laser as a light source is used, and as a method in the process, a phase shift mask (phase shift mask) using an exposure mask (photo mask) is used.
k) and a C.E.L. (co.) method of forming a separate thin film on the wafer to improve the image contrast.
ntrast enhancement layer (hereinafter referred to as CEL) method or S.O.G (spin on glass;
Trilayer resist (Tri la) with an intermediate layer such as SOG
A method of selectively injecting silicon above the photosensitive film has been developed to reduce the resolution limit value.

On the other hand, the size of the contact hole connecting the upper and lower conductive wirings and the distance between the wiring and the peripheral wiring are reduced as the element is highly integrated, and the aspect ratio, which is the ratio of the contact hole diameter to the depth, is obtained. ) Increases.
Therefore, in a highly integrated semiconductor device having a multi-layer conductive wiring, accurate and strict alignment between masks and the like in a manufacturing process is required to form a contact, and the process margin is reduced.

[0006] Such a contact hole has a misalignment tolerance at the time of mask alignment in order to maintain an interval.
nt tolerance), lens distortion during the exposure process (lens disto)
The mask is formed in consideration of factors such as critical dimension variation during mask fabrication and photo-etching, and registration between masks.

Further, a technique for forming a contact hole by a self-alignment method has been developed to overcome the limitations of a lithography process when forming a contact hole. The most preferable method for forming a self-aligned contact hole is a method using a nitride film as an etching barrier layer.

Although not shown, a method of manufacturing a contact hole of a conventional semiconductor device, for example, a charge storage electrode contact hole using a nitride film as an etching barrier will be described below.

First, a predetermined lower structure is provided on a semiconductor substrate.
For example, a MOS field effect transistor (Metal Oxide Semico
nductor Field Effect Transister; MOS FE
After that, a nitride film used as an etching barrier layer and an interlayer insulating film made of an oxide film material are sequentially formed on the entire surface of the structure.

Next, after forming a photosensitive film pattern exposing an interlayer insulating film on a portion of the semiconductor substrate that is to be formed in the charge storage electrode contact hole, the interlayer insulating film exposed by the photosensitive film pattern is formed. Is dry-etched using a carbon rich fluorocarbon gas to expose the nitride film, and the nitride film is etched again to form a contact hole.

The method of manufacturing a contact hole of a semiconductor device according to the prior art as described above includes dry etching under the condition that the difference in etching selectivity between the interlayer insulating film and the etching barrier layer is 5: 1 or more. Is exposed, and the exposed nitride film is removed again to form a contact hole exposing the semiconductor substrate. In the etching process, a large amount of polymer is generated in order to increase an etching selectivity. C ₂ F ₄ , C ₂
F ₆ , C ₃ F ₆ , C ₃ F ₈ , C ₄ F ₈ , C ₂ H ₂ , CH
₃ F, C ₂ HF ₅ etc. are used by mixing with an inert gas.
When a polymer generated during etching is deposited on an interlayer insulating film made of an oxide film, the polymer is continuously removed by oxygen generated from the oxide film and etching occurs, but the polymer is deposited on a nitride film. Since there is no etching source, the nitride film is not damaged.

Therefore, while the etching selectivity between the oxide film and the nitride film increases as the amount of the polymer increases, when the amount of the polymer is abnormally increased or the polymer of the component which is not etched is generated, a certain stage is reached. Etching stops.

Furthermore, as the C / F ratio increases, the production of polymer increases, and the problem of the above-mentioned etching stop increases.

On the other hand, when the difference in the etching selectivity between the oxide film and the nitride film becomes small, the nitride film is damaged at the time of etching the oxide film, and a conductive layer thereunder, for example, a semiconductor substrate is damaged, or the upper and lower wirings are damaged. In this case, a short circuit occurs, the process margin of the optimum process condition is small, and the reproducibility of the device is deteriorated, which causes another problem that the process yield and the reliability of the device operation are deteriorated.

Further, the etching chamber itself is also formed of a material that generates oxygen, such as quartz or aluminum oxide, and the outgassing during the etching process lowers the etching uniformity at the edge and center of the wafer. Has problems.

[0016]

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object of the present invention is to provide a SAC manufacturing process using a nitride film as an etching barrier layer in contact hole etching. In order to obtain an appropriate etching selectivity between the nitride film and the oxide film, the carbon film is spontaneously dissociated into the perfluorocarbon gas, and the CO gas for maintaining the partial pressure of C and O is added to damage the nitride film by the C component. The difference in etching selectivity is maintained so that the O component prevents etching stoppage due to the polymer, so that the reproducibility is excellent, the margin of the optimal process conditions increases, the uniformity of the etching increases, and the process yield and An object of the present invention is to provide a method for manufacturing a contact hole of a semiconductor device, which can improve the reliability of device operation.

[0017]

A feature of a method for manufacturing a contact hole of a semiconductor device according to the present invention for achieving the above object is that an etching barrier layer is formed on a semiconductor substrate having a predetermined lower structure. Forming a film, forming an interlayer insulating film on the nitride film, forming a photosensitive film pattern exposing a portion of the interlayer insulating film that is to be formed in a contact hole, and forming the photosensitive film pattern. Removing the exposed interlayer insulating film and exposing the nitride film by using a mixed gas of a percarbonated carbon fluoride gas and a CO gas, and removing the nitride film to form a contact hole. It is to provide a process.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a method for manufacturing a contact hole of a semiconductor device according to the present invention will be described in detail with reference to the accompanying drawings.

FIGS. 1 and 2 are views showing a process of manufacturing a contact hole of a semiconductor device according to the present invention, which is an example of a charge storage electrode SAC using a nitride film as an etching barrier layer.

First, a gate oxide film (11) and a gate electrode (1) are formed on a semiconductor substrate (10), for example, a silicon wafer.
2), spacer (13) and LDD (lightly dope)
After forming a MOS FET composed of source / drain regions (14) having a d drain (hereinafter referred to as LDD) structure, a nitride film (15) used as an etching barrier layer at the time of contact hole etching is formed on the entire surface of the structure. Is formed, and an interlayer insulating film (16) is sequentially formed thereon.

At this time, the interlayer insulating film (16) is made of BPS.
G (Boro Phospho Silicate Glass; hereinafter referred to as BPSG), TEOS (Tetra Ethyl Ortho Silicate; hereinafter referred to as TEOS), PSG (Phospho Silicate Glass;
(PSG) or the like.

Next, a photosensitive film pattern (18) for a charge storage electrode contact mask is formed. (See Fig. 1)

Thereafter, the nitride film (15) is exposed by dry-etching the interlayer insulating film (16) exposed by the photosensitive film pattern (18) using an etching gas obtained by mixing a CO gas and a perfluorocarbon gas. Let it.

At this time, the dry etching process is performed by using a carbon-carbon fluoride gas, for example, C ₂ F ₄ , C ₂ F ₆ , C ₃ F ₆ ,
Any one of the group consisting of C ₃ F ₈ , C ₄ F ₈ , CH ₃ F and C ₂ HF ₅ may be used, or a combination thereof or C ₂ H ₂ , CH ₂ F ₂ , One or more of H ₂ are used in combination.

Here, the CO component is dissociated so that the C component maintains a difference in the etching selectivity to the extent that the nitride film (15) is not damaged, and the O component serves as an etching source to prevent the polymer from stopping the etching. Then, an inert gas such as Ar or H is added to the mixed gas.
In some cases, e, Ne, N ₂ , or the like is used as a mixture.

Further, the dry etching step is performed for 500 times.
~ 3000 Watts of source power, 500-30
It is performed under the process conditions of a bias power of 00 watts, a pressure of 1 to 150 mTorr, and an electrode temperature of about −50 to 50 ° C.
The etching gas is 5-50 sccm (standard cubic c
C ₃ F ₈ of entimeter), C ₄ F of 5~30sccm
₈ or 1-30 sccm of CO gas is used as a percarbonated carbon fluoride gas such as CH ₃ F, but 0 to 500 sccm of Ar gas or 0 to 500 sccc is used.
m helium gas may be mixed.

Further, other percarbonated carbon fluoride gases used in the dry etching process include C ₂ F ₄ , C ₂ F ₆ and C _3.
Optimal gas flow rate F _6, C ₂ HF ₅ and C ₂ H ₂ are respectively 5～40,10～50,5～40,1～30 and 1～30Sccm.

Next, the exposed nitride film (1)
5) is removed by a continuous dry etching method to complete a contact hole (20) exposing the semiconductor substrate (10). (See Fig. 2)

FIGS. 3 to 6 are graphs showing the etching rate of the interlayer insulating film with respect to the flow rate of the dry etching gas used in the present invention.

FIG. 3 shows C ₂ F ₄ , C ₂ F ₆ , C ₃ F
₆ shows the etching rate of the interlayer insulating film with the flow rate of C ₃ F ₈ or C ₂ HF ₅ gas, and is indicated by a straight line having a positive slope. Here, the C ₂ F ₄ ,
C ₂ F ₆ , C ₃ F ₆ , C ₄ F ₈ and C ₂ HF ₅ gases are
It is a main etching gas for an oxide film forming the interlayer insulating film.

FIG. 4 shows C ₂ H ₂ , CH ₃ F, CH ₂
It shows the etching rate of the interlayer insulating film according to the flow rate of gas such as F ₂ or H ₂ , and the upper part is formed in a convex shape, but C ₂ H ₂ , CH ₃ F, CH ₂ F ₂ or The maximum point of the etching rate according to the gas flow rate such as H ₂ is C ₄ F ₈ / Ar, C
₃ influenced by F ₈ / Ar, and other variables may change.

FIG. 5 shows the etching rate of the interlayer insulating film in accordance with the CO gas flow rate. The upper part of the etching rate in accordance with the gas flow rate is partially convex, but the maximum point of the etching rate in accordance with the gas flow rate is determined by other variables. May be affected by the change.

FIG. 6 shows the etching rate of the interlayer insulating film depending on the flow rate of gas such as Ar, He, Ne or N _2. The minimum point of the etching rate may change due to other variables.

On the other hand, the graphs shown in FIGS.
Said C_Two H_Two , CH_Three F, CH_Two F _Two , H_Two Such as gas,
CO gas and Ar, He, Ne, N_Two The gas of the above is C
_Two F_Four , C_Two F₆ , C_Three F₆ , C_Three F₈ , C_Four F₈ as well as
C_Two HF_Five Used with major etching gases such as
You.

[0035]

As described above, the method for fabricating a contact hole in a semiconductor device according to the present invention is a SAC using a nitride film as an etching barrier layer, and a method of manufacturing a contact hole in an interlayer insulating film on a nitride film. Since a mixture of fluorine gas and carbon monoxide gas is used, the difference in etching selectivity between the oxide film and the nitride film is increased by C dissociated from CO, so that the nitride film is not damaged, and the O component is etched by the polymer. Prevents stoppage, excellent process reproducibility, prevents damage to substrate because nitride film is not damaged, increases margin of optimal process conditions, increases uniformity of etching, increases process yield and reliability of device operation This has the advantage that the performance can be improved.

[Brief description of the drawings]

FIG. 1 is a process diagram of manufacturing a contact hole of a semiconductor device according to the present invention.

FIG. 2 is a process diagram of manufacturing a contact hole of a semiconductor device according to the present invention.

FIG. 3 is a graph showing an etching rate of an interlayer insulating film with respect to a flow rate of a dry etching gas used in the present invention.

FIG. 4 is a graph showing an etching rate of an interlayer insulating film with respect to a flow rate of a dry etching gas used in the present invention.

FIG. 5 is a graph showing an etching rate of an interlayer insulating film with respect to a flow rate of a dry etching gas used in the present invention.

FIG. 6 is a graph showing an etching rate of an interlayer insulating film with respect to a flow rate of a dry etching gas used in the present invention.

DESCRIPTION OF SYMBOLS 10 Semiconductor substrate 11 Gate oxide film 12 Gate electrode 13 Spacer 14 Source / drain region 15 Nitride film 16 Interlayer insulating film 18 Photosensitive film pattern 20 Contact hole

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Kim Masahiro 136-1 Misatoyama, Fangbachi-eup, Icheon-si, Gyeonggi-do, Republic of Korea (72) Inventor Kim Masao Fang, Fang-eup-eup, Icheon, Gyeonggi-do, Republic of Korea 136-1 Misatoyama Inside Hyundai Electronics Industry Co., Ltd.

Claims (8)

[Claims] A step of forming an etching barrier layer with a nitride film on a semiconductor substrate having a lower structure; a step of forming an interlayer insulating film on the nitride film; and exposing a contact hole portion in the interlayer insulating film. Forming a photoresist pattern to be exposed; removing an interlayer insulating film exposed by the photoresist pattern to expose a nitride film, but performing etching using a mixed gas of a percarbonated carbon fluoride gas and a CO gas. Forming a contact hole by removing the nitride film. 2. The method according to claim 1, wherein the interlayer insulating film is BPSG or TEOS.
2. The method according to claim 1, wherein the contact hole is formed of any one of PSG. 3. The method of claim ₂ , wherein the percarbonated fluorocarbon gas is C ₂ F ₄ ,
C ₂ F ₆ , C ₃ F ₆ , C ₃ F ₈ , C ₄ F ₈ , CH ₃ F,
Any one of C ₂ HF ₅ , a combination thereof, or the selected gas may be C ₂ F ₄ , CH ₂ F ₂ , H ₂
2. The method according to claim 1, wherein at least one of the components is mixed.
The method for producing a contact hole of a semiconductor device according to the above. 4. The method according to claim 1, wherein the perfluorocarbon gas is 5 to 50 seconds.
C ₃ F ₈ gas ccm, C ₄ F ₈ gas 5~30sccm, CH ₃ F gas 1~30sccm, 5~40scc
C ₂ F ₄ gas m, C ₂ F ₆ gas 20~50sccm, C ₃ F ₆ gas 5~40sccm, 1~30scc
m C ₂ F ₂ gas or 1-30 sccm C ₂ HF ₅
4. The method according to claim 1, wherein the contact hole is used as a gas. 5. The method according to claim 1, wherein the CO gas is used at a flow rate of about 1 to 30 sccm. 6. The method of claim 1, wherein the etching using the mixed gas is performed by adding an inert gas to the mixed etching gas. 7. The method according to claim 1, wherein the inert gas is 0 to 500 sccm.
7. Ar or He is used.
The method for producing a contact hole of a semiconductor device according to the above. 8. The etching process using the mixed gas includes a source power of 500 to 3000 watts, and a power of 500 to 3000 watts.
2. The method according to claim 1, wherein a bias power of 000 watts, a pressure of 1 to 150 mTorr, and an electrode temperature of about -50 to 50 [deg.] C. are used as process conditions.