KR20050001207A - method for fabricating storge node electrodes of capacitor - Google Patents

Abstract

PURPOSE: A method for forming a storage node electrode of a capacitor is provided to prevent a capacitor from collapsing and avoid a short circuit between adjacent capacitors by forming a storage node electrode of a stable cone type. CONSTITUTION: A semiconductor substrate(100) including a conductive plug(104) is prepared. A cap oxide layer(106) to which dopants of higher density are injected as it goes to the lower part is formed on the front surface of the substrate. The cap oxide layer is selectively etched to form a storage node contact of a cone type exposing the conductive plug. A polycrystalline silicon layer and a photoresist layer are formed on the front surface of the storage node contact structure. A CMP(chemical mechanical polishing) process is performed on the photoresist layer and the polycrystalline silicon layer until the cap oxide layer is exposed. The remaining photoresist layer is eliminated.

Description

Method for fabricating storge node electrodes of capacitor

The present invention relates to a method of manufacturing a semiconductor device, and more particularly, to a method of forming a storage node electrode of a capacitor capable of securing a high capacitance.

In general, as the high integration of semiconductor devices is increased, a high capacitance of a capacitor is required. In order to solve this problem, a method of using a material having a high dielectric constant of a capacitor, decreasing a thickness of a dielectric film, or manufacturing a high capacitor has emerged. Hereinafter, a method of manufacturing a high height of the capacitor will be described as one of the measures for the fixed capacitance of the capacitor.

1A to 1D are manufacturing process diagrams illustrating a method of forming a storage node electrode of a capacitor according to the prior art.

First, as shown in FIG. 1A, a semiconductor substrate 10 provided with a transistor (not shown) is provided. Subsequently, after the interlayer insulating layer 12 is formed on the substrate 10, via holes 13 are formed by selectively etching portions of the interlayer insulating layer 12. Thereafter, a first polycrystalline silicon film (not shown) is formed on the entire surface of the substrate including the via hole 13, and the conductive plug is embedded in the via hole 13 by CMP (Chemical Mechnical Polishing). 14).

Subsequently, after the cap oxide layer 16 is formed on the entire surface of the substrate including the conductive plug 14, the photoresist pattern 30 exposing a portion corresponding to the conductive plug 14 on the cap oxide layer 16 is exposed. To form.

Subsequently, as shown in FIG. 1B, the cap oxide layer 16 is etched using the photoresist pattern as a mask to form a storage node contact 17.

Next, as shown in FIG. 1C, a second polycrystalline silicon film 18 and a photoresist film 20 are sequentially formed on the entire structure of the storage node contact 17.

Thereafter, as shown in FIG. 1D, the photoresist film and the second polycrystalline silicon film are CMPed, and the remaining cap oxide film is removed to form the storage node electrode S1 of the capacitor.

Subsequently, as shown in FIG. 1D, a dielectric film 20 and a third polycrystalline silicon film 22 for plate electrodes are sequentially formed to manufacture a capacitor of a semiconductor device. An oxide-nitride-oxide (ONO) structure is used as the dielectric layer 20.

Figure 2 is a SEM photograph for explaining the problem according to the prior art, part A shows that the fall of the capacitor occurs. In addition, in FIG. 2, part B shows a normal capacitor without collapse, and part C shows that the storage node contact size is smaller than the upper part.

In the prior art, the cap oxide film thickness must be increased in order to increase the height of the capacitor. However, when the cap oxide film thickness is increased, as shown in part C of FIG. 2, a fall of a capacitor (part A) occurs, and the collapsed capacitor is shorted by being attached to a neighboring capacitor.

In particular, in the structure in which the storage node contact size is smaller than the upper portion (see C), the capacitor is very vulnerable to the force in the transverse direction, thereby accelerating the capacitor collapse.

Accordingly, an object of the present invention for solving the above problems is to provide a method of forming a storage node electrode of a capacitor capable of stably increasing the height of the capacitor without falling of the capacitor.

1a to 1d is a manufacturing process diagram for explaining a storage node electrode forming method of a capacitor according to the prior art.

Figure 2 is a SEM photograph for explaining the problem according to the prior art.

3A to 3D are manufacturing process diagrams illustrating a method of forming a storage node electrode of a capacitor according to the present invention.

In order to achieve the above object, the method of forming a storage node electrode of a capacitor according to the present invention comprises the steps of providing a semiconductor substrate including a conductive plug, and forming a cap oxide film implanted with a high concentration of dopant toward the bottom of the substrate Forming a conical storage node contact to expose the conductive plug by selectively etching the cap oxide film; sequentially forming a polycrystalline silicon film and a photoresist film on the entire surface of the storage node contact structure; and until the cap oxide film is exposed. CMP of the photosensitive film and the polycrystalline silicon film to form a storage node electrode, and removing the remaining photosensitive film.

As the dopant to be injected into the cap oxide film, boron or phosphorus ions are used.

3A to 3D are cross-sectional views illustrating a method of forming a storage node electrode of a capacitor according to the present invention.

A method of forming a storage node electrode of a capacitor according to the present invention, as shown in Figure 3a, provides a semiconductor substrate 100 provided with a transistor (not shown). Subsequently, after the interlayer insulating layer 102 is formed on the substrate 100, the via hole 103 is formed by selectively etching the interlayer insulating layer 102. Next, a first polycrystalline silicon film (not shown) is formed on the entire surface of the substrate including the via hole 103, and the conductive plug 104 is formed by filling the via hole 103 by CMP of the first polycrystalline silicon film.

Thereafter, a cap oxide film 106 in which boron or phosphorus dopant is implanted is formed on the entire surface of the substrate including the conductive plug 104, and then the conductive plug 104 is formed on the cap oxide film 106. The photosensitive film pattern 130 exposing the site is formed. At this time, the dopant implantation of the cap oxide film 106 is to be changed in a stepwise manner rather than a continuous linear.

That is, the cap oxide film 106 has a large amount of dopant injected into the lower portion, and a small amount of the dopant is injected into the upper portion of the cap oxide film 106, so that a large amount of dopant is injected in a subsequent etching process. The lower portion of 106) shows higher etching ratio than the upper portion.

Subsequently, as shown in FIG. 3B, the cap oxide layer 106 is etched using the photoresist pattern as a mask to form a storage node contact 107. In this case, the cap oxide layer 106 has a characteristic that the lower portion of the dopant implanted with a high concentration is higher than the upper portion injected with a low concentration, the etch ratio is higher, the storage node contact 107 has a lower conical shape than the upper do. Accordingly, the conical storage node contact 107 has a wide bottom area and thus has a stable structure.

Then, the photoresist pattern is removed.

Thereafter, as shown in FIG. 3C, a second polycrystalline silicon film 108 and a photoresist film 120 are sequentially formed on the entire surface of the conical storage node contact 107 structure.

Subsequently, as illustrated in FIG. 3D, the photoresist film and the second polycrystalline silicon film are CMPed, and then the remaining cap oxide film is removed to form the storage node electrode S2 of the capacitor. In this case, the storage node electrode S2 has a stable conical shape having a lower area than that of the upper part.

Subsequently, in the subsequent process, the dielectric film 122 having the ONO structure and the third polycrystalline silicon film 124 for the plate electrode are sequentially formed to complete the manufacturing of the capacitor of the semiconductor device.

According to the present invention, when the cap oxide film is deposited, the dopant implantation concentration is adjusted stepwise so that the lower portion of the cap oxide film is injected at a higher concentration than the upper portion, so that the cap oxide film is etched in a subsequent process. Since the lower portion has a higher etching ratio than the upper portion, the storage node contact shape can be manufactured in a stable cone structure.

As described above, the present invention is to inject a dopant into the cap oxide film, the lower concentration of the dopant is injected to the lower portion of the cap oxide film than the upper, in the subsequent cap oxide film etching process, the high concentration dopant is injected cap The lower portion of the oxide layer may have a higher etching ratio than the upper portion, thereby manufacturing a stable cone-shaped storage node contact and a storage node electrode of a capacitor.

Accordingly, the conical storage node electrode has a lower structure having a more stable structure than the upper portion, and thus has a strong resistance to lateral pressure, thereby preventing the capacitor from falling down and shorting between adjacent capacitors.

In addition, this invention can be implemented in various changes within the range which does not deviate from the summary.

Claims (3)

Providing a semiconductor substrate including a conductive plug, Forming a cap oxide film in which a dopant is injected at a high concentration toward the bottom of the substrate; Selectively etching the cap oxide layer to form a conical storage node contact exposing the conductive plug; Sequentially forming a polycrystalline silicon film and a photoresist film on the entire storage node contact structure; Forming a storage node electrode by CMP of the photoresist film and the polycrystalline silicon film until the cap oxide film is exposed; And removing the remaining photoresist layer. The method of claim 1, wherein the dopant is boron or phosphorus ions. The method of claim 1, wherein the cap oxide layer is changed in a stepwise manner when the dopant is injected.