KR19980038845A - Metal contact method of semiconductor device - Google Patents

Abstract

1. TECHNICAL FIELD OF THE INVENTION

Semiconductor device manufacturing method

2. The technical problem to be solved by the invention

In the BOE cleaning process for removing the contact point and the natural oxide film generated during the contact hole etching, a part of the insulating film protrudes due to the jaw, which causes voids in the subsequent deposition of the aluminum film.

3. Summary of Solution to Invention

The purpose of the present invention is to provide a metal contact method that rounds the peaks of contact holes and effectively removes natural oxide films by dry cleaning using CF ₄ / O ₂ / Ar plasma after contact hole etching.

4. Important uses of the invention

Used to form metal contacts in semiconductor devices

Description

Metal contact method of semiconductor device

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a metal contact method of a semiconductor device, and more particularly to a metal contact method of a semiconductor device having improved step coverage of a metal film.

In general, metal contacts of semiconductor devices have used a method of sputtering using aluminum. However, as the semiconductor device is highly integrated, the size of the metal contact hole gradually decreases, and thus, the process margin is gradually reduced when the aluminum film is deposited, resulting in an over-hang phenomenon in the contact, thereby covering the step coverage of the aluminum film. It became difficult to secure. In order to solve this problem, the aluminum film deposition temperature is increased to increase the step coverage, but there is another problem such as causing a metal residue when etching the aluminum film.

In addition, a buffered oxide etch (BOE) solution cleaning process is performed to remove the natural oxide layer before the aluminum layer is buried in the contact hole. In this step, a portion of the insulating layer whose etching rate is relatively slow due to the etching rate difference between the insulating layers is contacted. Protruding into the hole causes voids in the aluminum filling.

In addition, since the contamination and damage occurs on the substrate in the dry etching step at the time of contact etching, the reliability of the semiconductor device is deteriorated, thus requiring a separate post-processing step.

In addition, in the case of a general wine glass type contact hole, the peak point of the contact hole also causes deterioration of the step coverage in the subsequent aluminum filling.

Hereinafter, a conventional metal contact method and its problems will be described with reference to the accompanying drawings, FIGS. 1A to 1D.

First, FIG. 1A illustrates a photoresist on an entire structure in which a BPSG (BoroPhosphoric Silicate Glass) film 11a, an IPO (InterPoly Oxide) 12, and a BPSG film 11b are sequentially stacked on a silicon substrate 10. After coating, the photoresist pattern 13 for metal contact is formed.

Next, as shown in FIG. 1B, the wet glass and the dry etching are sequentially performed to form a wine glass metal contact hole. Here, a cusp site A occurs. This pointed portion (A) is a cause of voids during the subsequent deposition of the aluminum film to deteriorate the step coverage of the metal film. That is, the aluminum film flows down along the contact hole surface, and the flow stops at the peak portion A so that the contact hole cannot be effectively buried.

Subsequently, the photoresist pattern 13 is removed as shown in FIG. 1C, and then a cleaning process is performed using a BOE solution. This process is performed to remove the natural oxide film formed on the silicon substrate 10. At this time, a portion of the interlayer insulating film BPSG film 11a, IPO 12, BPSG film 11b is etched. However, since the etching rates for the BOE solutions of the IPO 12 and the BPSG films 11a and 11b are different, that is, the BPSG films 11a and 11b doped with B and P as compared to the IPO 12 which is an undoped oxide film. Because of the fast etching speed of the relatively slow etching speed IPO (12) is to protrude.

Finally, as shown in FIG. 1D, a Ti / TiN film 14, which is a barrier metal, is deposited on top of the entire structure, and an aluminum film 15 is deposited on it. At this time, the Ti / TiN film 14 is cut off by the protruding IPO 12, and the aluminum film 15 is primarily formed by the IPO film 12 protruding secondly from the peak portion A. Deposition stops and an over-hang phenomenon occurs. That is, the aluminum film flows down along the contact hole wall, and the flow is stopped at the peak portion A and the jaw portion, causing voids. Such voids cause problems such as disconnection, resulting in a decrease in reliability of the semiconductor device.

SUMMARY OF THE INVENTION An object of the present invention is to provide a metal contact method for rounding the peaks of contact holes and effectively removing the native oxide layer by dry cleaning using CF ₄ / O ₂ / Ar plasma after contact hole etching.

1A to 1C are process diagrams of metal contact of a semiconductor device formed according to the prior art;

2A to 2D are metal contact process diagrams of a semiconductor device according to an embodiment of the present invention.

* Explanation of symbols for main parts of the drawings

10, 20: silicon substrate 11a, 11b, 21a, 21b: BPSG film

12, 22: IPO 13, 23: photoresist pattern

14, 24: Ti / TiN film 15, 25: aluminum film

A: cusp area

In order to achieve the above object, the present invention provides a method of manufacturing a semiconductor device, the method comprising: forming a photoresist pattern for forming a metal contact hole on a predetermined interlayer insulating layer formed on a semiconductor substrate, and etching the photoresist pattern Forming a metal contact hole that penetrates the predetermined interlayer insulating film by performing wet and dry etching sequentially as a barrier, removing the photoresist pattern and the natural oxide film formed on the semiconductor substrate, and removing the peaks generated during the contact hole etching. Dry cleaning using a plasma containing CF ₄ gas, O ₂ gas and Ar gas to round the surface, and filling the contact hole by forming a metal film on the entire structure.

Hereinafter, an embodiment of the present invention will be described in detail with reference to the accompanying drawings, FIGS. 2A to 2D.

First, in FIG. 2A, a photoresist is applied over an entire structure in a structure in which a BPSG film 21a, an IPO 22, and a BPSG film 21b are sequentially stacked on a silicon substrate 20. The state in which the photoresist pattern 23 is formed is shown.

Next, as shown in FIG. 2B, wet etching and dry etching are performed to form a wine glass metal contact hole. Here, a cusp site A occurs.

Subsequently, dry cleaning is performed using a CF ₄ / O ₂ / Ar plasma as shown in FIG. 1C. At this time, the peak portion A in the native oxide film and the contact hole formed on the exposed silicon substrate 20 is removed. Here, since Ar gas is self-stable as an inert gas, no chemical reaction occurs and only a physical action is performed. The O ₂ gas serves to oxidize and remove the damaged part on the silicon substrate 20 generated during the contact hole dry etching and to remove the photoresist pattern 23.

Finally, as shown in FIG. 2D, the Ti / TiN film 24, which is a barrier metal, is deposited on the entire structure, and then the aluminum film 25 is deposited to fill the contact holes.

The present invention described above is not limited to the above-described embodiments and the accompanying drawings, and various substitutions, modifications, and changes can be made in the art without departing from the technical spirit of the present invention. It will be apparent to those of ordinary knowledge.

As described above, the present invention performs a predetermined dry cleaning process after etching the contact hole, to sharpen the spots in the contact hole, and to prevent the bulging of a part of the conventional BOE cleaning process insulating film for removing the natural oxide film. In this way, the contact hole can be buried without voids in the subsequent aluminum filling process, thereby improving the reliability of the semiconductor device and improving the yield in the semiconductor device manufacturing process.

Claims (2)

A method of manufacturing a semiconductor device, comprising: forming a photoresist pattern for forming a metal contact hole on a predetermined interlayer insulating film formed on a semiconductor substrate, and performing wet and dry etching sequentially by using the photoresist pattern as an etch barrier. forming a metal contact hole penetrating the predetermined inter-layer insulating film, the photoresist pattern, and CF ₄ gas to remove the natural oxide film formed on a semiconductor substrate, and to round the cusp region occurred at the contact hole etching, O ₂ gas And dry cleaning using a plasma including Ar gas, and filling the contact hole by forming a metal film on the entire structure. The method of claim 1, further comprising forming a barrier metal film on the entire structure after the dry cleaning.