JP3559234B2 - Contact plug for pillar type storage node and method of manufacturing the same - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a structure of a pedestal type storage node in contact with a plug and a method of manufacturing the same, and more particularly, a pedestal including a seed layer having a shallow hole and a large-sized pedestal storage node. The present invention relates to a contact plug for a type storage node.
[0002]
[Prior art]
Under the condition that the same design standard is applied, the pillar-type storage node has a larger capacitance area than the concave-type storage node, but at present, the pillar-type storage node is manufactured using a conventional method. There is a tendency for confusion when etching the corners and critical dimensions of the profile and when the barrier layer is exposed due to misalignment.
[0003]
Then, H. Horri et al., “A Self-aligned stacked Capacitor using Novel Pt Electroplating Method for 1 Gbit DRAMs and Beyond” (see Symp. It has gained. As shown in FIG. 1, a seed layer 13 made of ruthenium (Ru) is deposited in a buried contact 12 having a diameter of 120 nm and a depth of 240 nm. Furthermore, a storage node 14 made of platinum (Pt) is formed on the Ru seed layer 13 by using a self-aligning Pt electroplating method used for the multilayer capacitor.
[0004]
[Problems to be solved by the invention]
However, forming a conformable seed layer by deposition in the buried contact of the Pt storage node described above is extremely difficult due to the large depth-to-width ratio of the buried contact (240 nm / 120 nm = 2). is there.
[0005]
Accordingly, it is an object of the present invention to provide a pillar type storage node contact plug having a shallow seed layer in a buried contact and a method of manufacturing the same.
[0006]
[Means for Solving the Problems]
The contact plug for a pillar type storage node according to the present invention includes an insulating layer, a conductive layer, a barrier layer, a seed layer, and a storage node, wherein the insulating layer has at least one buried contact. The conductive layer is formed in the buried contact. The barrier layer is formed on the conductive layer, the height obtained by adding a conductive layer and the barrier layer is not lower than the depth of the buried contact. Further, the seed layer is formed on the barrier layer and bulges upward at the edge of the opening of the buried contact. The pillar type storage node is formed on the seed layer.
[0007]
In this configuration, since the conductive layer and the barrier layer are provided inside the buried contact, the seed layer is located at an upper part, that is, a shallow portion in the buried contact. Therefore, the formation of the seed layer is facilitated, and a contact plug having a defect-free seed layer is obtained. It is also possible to increase the width of the buried contact, thereby increasing the electrical capacitance area of the storage node and increasing the tolerance for displacement due to the contact plug.
[0008]
The method of manufacturing a contact plug for a pillar type storage node according to the present invention includes: (a) providing a substrate; (b) forming a first insulating layer on the substrate; and (c) embedding the first insulating layer in the first insulating layer. Forming at least one contact, (d) forming a conductive layer and a barrier layer on the substrate in the buried contact by a series of deposition and etching (the height of the conductive layer plus the barrier layer is 20~40nm lower than the depth of the buried contacts), the step of forming the adaptive seed layer with respect to (e) the shape of the buried contact and the conductive layer on the first insulating layer and barrier layer, the (f) 2) forming an insulating layer and forming a hole connected to the buried contact therein; (g) forming a storage node for filling the hole on the seed layer; and (h) positioning on the first insulating layer. Second insulating layer and seed layer Comprising the step of removing.
[0009]
In this manufacturing method, by reducing the depth of the concave portion of the buried contact, the ratio of the depth to the width in the buried contact can be reduced, and the seed layer can be more adaptively deposited. The buried contact is formed by, for example, etching. At this time, it is easy to increase the width of the buried contact, and therefore, the tolerance of the area of the storage node and the displacement of the contact plug can be increased.
[0010]
The step of removing the seed layer located on the first insulating layer may employ etching. Here, by adjusting the etching parameters so that the etching rate of the seed layer is equal to the etching rate of the insulating layer below the seed layer, it is possible to prevent excessive etching of the remaining portion of the seed layer. Can be. As a result, a contact plug having a smoother surface on which a (Ba, Sr) TiO ₃ film (BST film) can be deposited is obtained.
[0011]
BEST MODE FOR CARRYING OUT THE INVENTION
In order to further clarify the objects, features and advantages of the present invention, preferred embodiments of the present invention will be described below with reference to the accompanying drawings.
[0012]
As shown in FIG. 2, the pillar type storage node contact plug includes an insulating layer (dielectric layer) 20, a buried contact 202 formed in the insulating layer 20, and a contact plug formed in the buried contact 202. A barrier layer 22 formed on the conductive layer 21 at a height not exceeding the opening of the buried contact 202, and an edge of the opening of the buried contact 202 formed on the barrier layer 22 And a pillar type storage node 24 formed on the seed layer 23.
[0013]
Here, the insulating layer 20 is made of SiO ₂ . Conductive layer 21 is made of polysilicon . The barrier layer 22 is made of TiN, TiSiN, TaSiN, or TiAlN. The seed layer 23 is made of Pt, Ir, or Ru. The storage node 24 is made of Pt.
[0014]
Hereinafter, the steps included in the method of manufacturing a pillar type storage node contact plug according to the present invention will be described in detail with reference to FIGS. 3 to 13, elements corresponding to the elements in FIG. 2 are denoted by the same reference numerals.
[0015]
First, as shown in FIG. 3, a 200-1000 nm-thick SiO ₂ insulating layer 20 is formed on a substrate 300 made of silicon by PECVD.
[0016]
Next, as shown in FIG. 4, the insulating layer 20 is patterned by an exposure and etching process to form a buried contact 202 having a diameter of 0.07 to 0.15 μm.
[0017]
Next, as shown in FIG. 5, after a polysilicon conductive layer 21 acting as a contact plug is deposited in the buried contact, the polysilicon is subjected to a chemical dry etching (CDE) step or a reactive ion etching (RIE) step. The silicon conductive layer 21 is etched back to a height lower than the opening of the buried contact 202 by about 70 to 170 nm. Further, the barrier layer 22 is deposited on the conductive layer 21, and is etched back by a CDE process or an RIE process using a chlorine-based gas such as Cl ₂ or BCl ₃ , so that the barrier layer 22 is about 20 to about 20 to less than the opening of the buried contact 202. Make the height 40 nm lower.
[0018]
Then, as shown in FIG. 6, a seed layer 23 made of Pt, Ir, or Ru and having a thickness of about 30 to 60 nm and adapted to the shape of the conductive layer is provided with an IMP (ionized metal). The barrier layer 22 and the insulating layer 20 are formed by a plasma, sputtering, or CVD process. The seed layer 23 adapted to the shape of the buried contact and the conductive layer functions as a stopping layer for etching and as an electrode for electroplating.
[0019]
Next, as shown in FIG. 7, another insulating layer 30 made of SiO ₂ and having a thickness of 200 to 1000 nm is formed on the seed layer by a PECVD process.
[0020]
Then, as shown in FIG. 8, a hole 302 of the seed layer 23 is formed by an exposure step and an etching step using an etching pattern having a size of about (0.07 to 0.15 μm) × (0.14 to 0.45 μm). Form. The pattern of the etched holes 302 defines the surface pattern of the subsequently formed storage node 24 (see FIGS. 10 and 12). Here, the surface area of the Pt storage node and the tolerance for the shift between the Pt storage node and the plug can be increased by enlarging the hole surface pattern using a wet etching process as shown in FIG. it can.
[0021]
Next, as shown in FIG. 11, a Pt storage node 24 is formed by a Pt electroplating process. During this step, the seed layer 23 is used as an electrode. The surface pattern of the Pt storage node is formed in a region defining the surface pattern of the hole 302 and surrounded by the insulating layer 30. In this way, a storage node with advantages such as vertical profile angle and minimum deviation in critical dimension is obtained.
[0022]
Then, as shown in FIG. 12, the insulating layer 30 is removed by a wet etching process or an RIE process using a fluorine-based gas. The seed layer 23 located on the surface of the insulating layer 20 is also removed by the RIE process. When SiO ₂ is etched, it is usually accompanied by an etching product of optical emission spectrometry (OES). The appearance of OES is considered an etch stop signal. Next, the etch selectivity between Pt / SiO _{2 and} between Ir / SiO ₂ was changed to Ar / O ₂ / Cl ₂ or Ar / O ₂ to prevent significant loss of the buried seed layer exposed during excessive etching. Adjust to about 1 by adjusting the flow rate of O ₂ / BCl ₃ . The barrier layer 22 and a subsequently formed BST film (not shown) are separated by the remaining seed layer 23 to prevent oxidation.
[0023]
Furthermore, when a Ru seed layer is applied to the above process, the loss of the surface of the Pt storage node is smaller because Pt itself is not easily etched by an etching gas mainly composed of oxygen, and therefore, a larger capacitance area is required. (See FIG. 13). However, the Ru seed layer located on the insulating layer has such a characteristic that current leaks more than the Pt or Ir seed layer. In contrast, when a Pt or Ir seed layer is used in the above process, the top edge of the Pt storage node is etched and rounded, thus reducing the capacitance area. On the other hand, the advantage of using the Pt or Ir seed layer is that the step is better covered when depositing the BST film and the upper electrode layer formed thereafter.
[0024]
Although the preferred embodiment of the present invention has been described herein, any person skilled in the art can make various modifications without departing from the technical idea of the present invention. The above embodiments are merely examples, and the technical scope of the present invention is as described in the claims.
[0025]
【The invention's effect】
The pillar-type storage node contact plug according to the present invention has a defect-free seed layer and reliably functions. In addition, a high-performance contact plug having a large electric capacitance area of the storage node and a large tolerance of a shift between the storage node and the plug is obtained.
[0026]
Further, the method of manufacturing a contact plug for a pillar-type storage node according to the present invention can easily provide a high-performance contact plug having a defect-free seed layer.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing a storage node according to a conventional technique.
FIG. 2 is a sectional view of a pillar type storage node contact plug according to an embodiment of the present invention.
FIG. 3 is a cross-sectional view illustrating an initial step of manufacturing a contact plug for a pillar-type storage node according to an embodiment of the present invention.
FIG. 4 is a cross-sectional view showing a step that follows the step of FIG.
FIG. 5 is a cross-sectional view showing a step that follows the step of FIG.
FIG. 6 is a cross-sectional view showing a step that follows the step of FIG.
FIG. 7 is a cross-sectional view showing a step that follows the step of FIG.
8 is a cross-sectional view showing a step that follows the step of FIG.
FIG. 9 is a sectional view showing a step obtained by modifying the step of FIG. 8;
FIG. 10 is a sectional view showing a step after the step in FIG. 9;
FIG. 11 is a cross-sectional view showing a step that follows the step of FIG.
FIG. 12 is a cross-sectional view showing a step that follows the step of FIG.
FIG. 13 is a cross-sectional view showing a step that follows the step of FIG.
[Explanation of symbols]
Reference Signs List 20: insulating layer, 21: conductive layer, 22: barrier layer, 23: seed layer, 24: pillar type storage node, 202: buried contact, 300: substrate

Claims (13)

An insulating layer having at least one buried contact; a conductive layer located in the buried contact; a barrier layer formed on the conductive layer; and an opening in the buried contact formed on the barrier layer. A contact layer comprising a seed layer bulging at an edge of a portion and a pillar-type storage node formed on the seed layer , wherein the height of the barrier layer and the conductive layer is the depth of the buried contact. 20 to 40 nm lower than the contact plug. A thickness of the insulating layer having the buried contact is 200 to 1000 nm; a height of the conductive layer located in the buried contact is 70 to 170 nm lower than a depth of the buried contact; 2. The contact plug according to claim 1 , wherein a height of the contact plug is 20 to 40 nm lower than a depth of the buried contact, and a height of the pillar-type storage node is 200 to 1000 nm. . Contact plug according to claim 1 or claim 2 the thickness of the seed layer is characterized in that it is a 30 to 60 nm. 4. The contact plug according to claim 1, wherein the insulating layer is made of SiO ₂ , and the conductive layer is made of polysilicon . 5. The contact plug according to any one of claims 1 to 4, wherein the barrier layer is made of any one of TiN, TiSiN, TiAlN, and TaSiN. The contact plug according to claim 1, wherein the seed layer is made of one of Pt, Ir, and Ru. 7. The contact plug according to claim 1, wherein the storage node is made of Pt. Providing a substrate, forming a first insulating layer on the substrate, forming at least one buried contact in the first insulating layer, and depositing and etching a conductive material in the buried contact. Forming a layer and forming a barrier layer on the conductive layer in the buried contact by depositing and etching such that the height added to the conductive layer is 20 to 40 nm lower than the depth of the buried contact Forming a seed layer conforming to the shape of the buried contact and the conductive layer on the first insulating layer and the barrier layer; and forming a second insulating layer on the seed layer. Forming a hole connected to the buried contact in the second insulating layer, forming a storage node in the hole on the seed layer, and positioning the storage node on the first insulating layer. Method for producing a contact plug, characterized removing the second insulating layer and the seed layer, in that it consists of. The method according to claim 8, wherein SiO ₂ is used as a material of the first insulating layer. 10. The method according to claim 8, wherein polysilicon is used as a material of the conductive layer. The method according to any one of claims 8 to 10, wherein any one of TiN, TiSiN, TiAlN, and TaSiN is used as a material of the barrier layer. The method of manufacturing a contact plug according to any one of claims 8 to 11, wherein one of Pt, Ir, and Ru is used as a material of the seed layer. 13. The method of manufacturing a contact plug according to claim 8, wherein Pt is used as a material of the storage node.

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