KR20020091891A - A forming method of contact - Google Patents

Abstract

PURPOSE: A method for forming a contact is provided to prevent losses of a hard mask and an interlayer dielectric by forming the contact after forming an etch stopper of an over-hang structure. CONSTITUTION: An insulating layer(35) for a spacer and an interlayer dielectric(36) are sequentially formed on a substrate(30) having gate patterns on which a gate oxide(31), a gate polysilicon layer(32), a gate silicide layer(33) and a nitride hard mask(34) are stacked sequentially. An etch stopper(37) is formed on the resultant structure so as to have an over-hang structure for covering the upper of the gate patterns and the sidewalls between adjacent gate patterns. Contact holes(38) are formed to expose the substrate(30) by selectively etching the etch stopper(37) of the over-hang structure and the insulating layer(35) for the spacer.

Description

A forming method of contact

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a semiconductor device, and more particularly, to a method of forming a contact, and more particularly, to a method of forming a landing plug contact.

Conventional plugs are formed in the vertical direction only at the contact forming site. Meanwhile, another plug for contact with another conductive pattern to be formed on the plug is formed in order to form a stacked structure of the device for improving the degree of integration. As the size decreases, the density decreases, and the possibility of short circuit due to misalignment increases, resulting in a decrease in process margin. Therefore, a landing plug that can be extended to the contact forming area and the surrounding area to increase the contact margin is mainly used. .

However, due to the high integration of semiconductor devices, such landing plug contact sizes become smaller and smaller, resulting in problems such as misalignment and contact open fail, and hard masks on the word lines due to contact formation are etched. As the probability of occurrence of short increases, this problem also remains a problem to be solved to improve the integration and yield of the device.

1A to 1C are cross-sectional views illustrating a process for forming a contact in the prior art, and FIG. 2 is a plan view illustrating a structure in which an interlayer insulating film is selectively etched in FIG. 1B.

First, as illustrated in FIG. 1A, a plurality of gate polysilicon layers 3 and a gate silicide layer 4 such as tungsten silicide are stacked on a substrate 1 on which various elements for forming a semiconductor device are formed. Form a word line.

Specifically, the gate oxide film 2 is formed between the substrate 1 and the gate polysilicon layer 3, and the gate silicide layer 4 is formed on the gate silicide layer 4 to prevent the loss of the gate due to subsequent self-aligned etching or the like. The hard mask nitride film 5 is formed.

Subsequently, the nitride film 6 for word line spacers and the interlayer insulating film 7 are sequentially formed on the entire surface of the substrate including the word lines, and then the interlayer insulating film 7 is subjected to a chemical mechanical polishing (CMP) process. After the planarization, the photoresist pattern 9 is formed on the interlayer insulating layer 7 to define a contact portion connected to the storage node and the bitline to be formed by a subsequent process.

Here, a-a 'and b-b' direction shows the direction in which the structure is cut in that direction on the plan view of FIG.

Next, as shown in FIG. 1B, a landing plug contact that connects the charge storage electrode and the bit line by etching the exposed portion of the interlayer insulating layer 7 by an etching process using the photoresist pattern 10 as an etching mask ( 8) is formed at the same time by a self-aligned contact (hereinafter referred to as SAC) method.

In the SAC process, an etching material having a high selectivity is used to minimize the attack of the hard mask nitride film 5, but the attack of the hard mask nitride film 5 such as 'E' is not completely prevented. Short circuits between the other plugs occur in the word line and subsequent processing.

In addition, in order to minimize the attack of the hard mask nitride film 5 during the SAC process, an etching material having a high selectivity is used, so that the hard mask nitride film 5 and the nitride nitride film 6 for the spacer are large amounts of polymer during etching. By inducing a slope (A) to the contact forming site by the polymer generated by the trigger, the open area such as 'B' is narrowed to act as a factor to increase the overall resistance of the device, or in severe cases 'C' and As contact open defects occur, this is likely to become a bigger problem as the integration speeds up, and such polymers are not easily removed through subsequent cleaning processes.

Next, as shown in FIG. 1C, a cleaning process is performed to remove the residues A such as polymers due to contact formation.

In this case, when the cleaning process is increased to increase the area of the contact portion by removing the polymer (A), loss of the interlayer insulating film 7 becomes severe as in 'D', resulting in inter-element isolation, which is an inherent characteristic of the interlayer insulating film. Isolation is reduced, thereby increasing the possibility of short circuit between devices.

Next, although not shown in the drawings, the polysilicon for plug contact is deposited on the entire surface of the resultant, and then the polysilicon layer and the interlayer insulating film 7 and the plug contact are contacted until the hard mask nitride film 5 is sufficiently exposed by the CMP process. The nitride film 6 for the spacer is polished to complete the poly contact forming process.

As described above, the conventional landing plug forming method has a fatal problem that is weak to meet the multilayer wiring structure and the contact size due to the high integration.

The present invention proposed to solve the problems of the prior art as described above, after forming an etch stop layer of the over-hang structure surrounding the top and sidewalls of one end of the exposed conductive pattern after etching the interlayer insulating layer to define the contact region The purpose of the present invention is to provide a method for forming a contact that can prevent the loss of a hard mask due to the formation of a contact, and can prevent the loss of an interlayer insulating film caused by a subsequent cleaning process.

Another object of the present invention is to provide a contact forming method capable of preventing contact open defects by reducing the deposition thickness of an insulating film for a spacer.

1A to 1C are cross-sectional views illustrating a process for forming a contact according to the prior art;

2 is a plan view showing a structure in which an interlayer insulating film is selectively etched;

3A to 3D are cross-sectional views illustrating a process for forming a contact in the present invention;

FIG. 4 is a SEM photograph showing that the hard mask is protected by the etch stop layer of the over-hang structure. FIG.

* Explanation of symbols for the main parts of the drawings

30: substrate

31: gate oxide film

32: polysilicon layer for gate

33: silicide layer for gate

34: hard mask nitride film

35: insulating film for spacer

36: interlayer insulating film

37: etching prevention film

38: contact hole

In order to solve the above problems, the present invention includes a first step of sequentially forming an insulating film for a spacer and an interlayer insulating film along a surface on a substrate on which a plurality of neighboring conductive patterns are formed; Selectively etching the interlayer insulating film to expose the spacer insulating film between the adjacent conductive patterns while exposing an upper portion of each end of the neighboring conductive pattern; A third step of forming an etch stop layer on the finished product of the second step, and having an over-hang structure covering a sidewall between an upper portion of each end of the conductive pattern and the neighboring conductive pattern; And a fourth step of selectively etching the etch stop layer and the spacer insulating layer between the conductive patterns to expose the substrate.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings, in order to enable those skilled in the art to more easily implement the present invention.

3A to 3D are cross-sectional views illustrating a contact forming process according to an embodiment of the present invention.

First, as illustrated in FIG. 3A, a plurality of gate polysilicon layers 32 and a gate silicide layer 33 such as tungsten silicide are stacked on a substrate 30 on which various elements for forming a semiconductor device are formed. A conductive pattern, for example, a word line (hereinafter referred to as a word line) is formed.

That is, a gate oxide film 31 is formed between the substrate 30 and the gate polysilicon layer 32, and the nitride film for preventing the loss of the gate due to subsequent self-aligned etching or the like on the gate silicide layer 33. A hard mask 34 of the back is formed.

Subsequently, an insulating film 35 for word line spacers such as a nitride film and the interlayer insulating film 36 are sequentially formed on the entire surface of the substrate including the word line, and then the interlayer insulating film 36 is planarized by a CMP process, and then, by a subsequent process. A photoresist pattern 39 is formed on the interlayer insulating layer 36 to define a portion of the charge storage electrode to be formed and a contact portion connected to the bit line.

Specifically, the word line spacer insulating film 35 has a thickness of 50 kPa to 200 kPa thinner than that of a conventional spacer nitride film. The interlayer insulating film 36 may include a BoroPhosphor Silicate Glass (HDPS), a High Density Plasma (HDP) oxide film, or a PSG. An oxide-based material film such as (Phospho-Silicate Glass) is used.

Here, a-a 'and b-b' direction shows the direction in which the structure is cut in that direction on the plan view of FIG.

Next, as shown in FIG. 3B, the interlayer insulating layer 36 is selectively etched by an etching process using the photoresist pattern 39 as an etching mask to define a region to be formed for contact formation between the charge storage electrode and the bit line. In this case, the upper portion of each end of the neighboring word line is exposed while exposing the insulating film 35 for the word line spacer between the neighboring word lines.

At this time, while maintaining a pressure of 15 mTorr to 50 mTorr and a power of 1000W to 2000W, gas such as C ₄ F ₈ , CH ₂ F ₂ , Ar, O ₂ , Co, or a mixed gas thereof is used.

At this time, the substrate 40 between the interlayer insulating films 46 is exposed in the cross section in the b-b 'direction.

Subsequently, a washing process is performed to remove the polymer, a by-product generated during etching, and a buffered oxide etchant including sulfuric acid (H ₂ SO ₄ ) and hydrogen peroxide (H ₂ O ₂ ) mixed at 300: 1. Etchant; BOE) for 70 seconds to 200 seconds.

As described above, by depositing the insulating layer 35 for the spacer thinner than in the related art, the process margin is increased during etching, and thus the amount of polymer produced is reduced, thereby increasing the area in the contact region and at the same time, in the case of other contact open defects. Probability can be minimized.

Next, as illustrated in FIG. 3C, an etch stop layer 37 is formed on the resultant, and an over-hang structure covering a sidewall between an upper portion of each end of the word line and a neighboring word line is formed. To form.

In this case, the etch stop layer 37 is for preventing the loss of the hard mask 34 due to the subsequent etching process, and there is no flow because there is no impurity doping, so that the step coverage is relatively low. By appropriate process conditions, such as to make the over-hang structure only on the top of the exposed surface, the thickness of the upper end of each end of the word line of the over-hang structure to 800 ~ 1500Å, bar plasma chemical vapor Plasma Enhanced Chemical Vapor Deposition (hereinafter referred to as PECVD) is used.

At this time, a source gas containing SiH ₄ of 200 SCCM to 300 SCCM and N ₂ of 6000 SCCM to 8000 SCCM and H ₂ of 2000 SCCM to 4000 SCCM was used, and the temperature of 300 ° C. to 500 ° C. and 1500 mTorr to 2500 mTorr were used. It is deposited under the pressure of 800W to 1500W while adjusting the power.

Subsequently, the USG component deposited in the contact is removed again by washing, and the same treatment is performed as described above.

Next, as shown in FIG. 3D, the etch stop layer 37 and the spacer insulating layer 35 are selectively etched to form a contact hole 38 exposing the substrate 30 between the word lines, followed by cleaning. Under the same conditions, the cleaning process is performed to remove the byproduct polymer. In b-b ', the etch-by film 37 remains as an over-hang structure that protects the sidewall of the interlayer insulating film 36. As a result, the loss of the interlayer insulating film 36 is prevented, and in the a-a ', the polymer is sufficiently removed through a cleaning process, and as the contact region is secured in advance by the insulating film 35 for the spacer, contact open defects and the like are prevented. The problem can be prevented, and the increase in resistance due to the decrease in the contact area can be minimized.

Here, during etching for forming the contact hole 38, the pressure is performed under a pressure of 20 mTorr to 50 mTorr and a power of 300 W to 800 W, and a gas such as CF ₄ , CHF ₃ , Ar, or a mixed gas thereof is used.

4 is a SEM (Scanning Electron Microscopy) photograph showing that the hard mask 34 is protected by the etch stop layer 37 having an over-hang structure.

Next, although not shown in the drawings, the polysilicon for plug contact is deposited on the entire surface of the resultant, and then the polysilicon layer for the plug contact, the interlayer insulating layer 36 and the spacer until the hard mask 34 is sufficiently exposed by the CMP process. The subsequent CMP process may be omitted by polishing the insulating film 35 or by partially filling the inside of the contact hole 38 using the selective epitaxial growth (SEG) method.

According to the present invention as described above, the insulating layer for the spacer is thinly deposited before the landing plug contact is formed to secure a wide area of the contact area when forming the contact, and the etch stop layer of the over-hang structure is formed after the interlayer insulating layer is etched for forming the contact. As a result, the present invention has been found to prevent the loss of the hard mask according to the subsequent etching process, prevent the loss of the interlayer insulating layer due to the cleaning process, and prevent the contact open defect.

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

The present invention as described above, by securing a wide contact area when forming a contact, it is possible to prevent contact resistance reduction and contact open defects, to prevent the loss of the interlayer insulating film due to the cleaning process to minimize the possibility of short circuit between devices, contact By preventing the short circuit between devices due to the loss of the hard mask during the etching for formation, it can be expected that the excellent effect that can ultimately improve the characteristics and yield of the device.

Claims (15)

In the semiconductor device manufacturing method, A first step of sequentially forming an insulating film for a spacer and an interlayer insulating film along a surface on a substrate on which a plurality of neighboring conductive patterns are formed; Selectively etching the interlayer insulating film to expose the spacer insulating film between the adjacent conductive patterns while exposing an upper portion of each end of the neighboring conductive pattern; A third step of forming an etch stop layer on the finished product of the second step, and having an over-hang structure covering a sidewall between an upper portion of each end of the conductive pattern and the neighboring conductive pattern; And A fourth step of selectively etching the etch stop layer and the spacer insulating layer between the conductive patterns to expose the substrate Contact forming method comprising a. The method of claim 1, The etch stop layer is USG (Undoped Silicate Glass) characterized in that the contact forming method. The method of claim 1, The etch stop layer is a contact forming method, characterized in that the thickness of 800 ~ 1500Å. The method of claim 1, The etch stop layer is formed by a plasma chemical vapor deposition method. The method of claim 4, wherein The etch stop layer is formed in a gas atmosphere comprising a SiH ₄ of 200 SCCM to 300 SCCM and N ₂ of 6000 SCCM to 8000 SCCM and H ₂ of 2000 SCCM to 4000 SCCM. The method of claim 4, wherein The etch stop layer is formed under a temperature of 300 ℃ to 500 ℃, a pressure of 1500 mTorr to 2500 mTorr and a power of 800W to 1500W. The method of claim 1, The insulating film for spacers is a nitride film. The method of claim 1, The spacer insulating film has a thickness of 50 kPa to 200 kPa. The method of claim 1, The etching of the second step, the method of forming a contact, characterized in that using at least one gas of C ₄ F ₈ , CH ₂ F ₂ , O ₂ , CO or Ar. The method of claim 9, The etching of the second step, maintaining a pressure of 15 mTorr to 50 mTorr, using a power of 1000W to 2000W. The method of claim 1, And after the second step, the third step, and the fourth step, further cleaning. The method of claim 11, The cleaning is performed by using a buffered oxide film etchant mixed with sulfuric acid and hydrogen peroxide in a ratio of 300: 1. The method of claim 11, The cleaning is performed, the contact forming method, characterized in that performed for 70 seconds to 200 seconds. The method of claim 1, The method of claim 1, The etching of the fourth step, the method of forming a contact, characterized in that using at least one gas of CHF ₃ , CF ₄ or Ar. The method of claim 14, The etching of the fourth step, the contact forming method characterized in that using a power of 300W to 800W under a pressure of 20 mTorr to 50 mTorr.