TW447120B - Method for making capacitor including a plasma cleaning step - Google Patents

Abstract

The present invention relates to a method for forming a capacitor, which comprises an oxygen plasma cleaning step for treating the oxides on the surface of a metal electrode and a dielectric layer. The cleaning step can be an oxygen plasma method, or a plasma method using a mixture gas of oxygen (O2) and tetrafluoro-methane (CF4). This method reduces the formation of a native oxidation layer or a metal oxidation layer for thereby reducing a leakage current and obtaining a stable voltage coefficient.

Description

447120 V. Description of the invention (l) Field of the invention: The present invention relates to a method of manufacturing a capacitor ', and particularly to a method including a gas plasma cleaning step to form a capacitor. * Background of the invention: _

Semiconductor element capacitors usually consist of two electrodes and a dielectric between the two electrodes. This structure is commonly used on many semiconductor devices, such as dynamic random access memory (DRAM). The manufacturing process of such a capacitor is usually as follows. First, a conductive layer is formed on the substrate, the pattern is escaped, and a time is left to form a lower electrode of the electric valley. Next, a dielectric layer is formed on the lower electrode. Finally, another conductive layer is used to cover the dielectric layer as an electrode on the capacitor, thus forming a capacitor.

The capacitance of a capacitor is related to the area of the electrode, the distance between the two electrodes, and the dielectric constant of the dielectric layer. There are several ways to increase the capacitance of a capacitor ' including increasing the area of the electrode, reducing the thickness of the dielectric layer, and using a dielectric material with a high dielectric constant. The material of the electrode includes at least polycrystalline silicon, polycrystalline metal silicide, and metal. Since the quality of a metal electrode capacitor is better than that of a polycrystalline silicon capacitor, the metal-insulator-metal (MIM) capacitors are usually formed with a metal layer for the lower electrode.

Page 4. ¾ ^ 447120 Five 'Invention Description (2) However, due to the presence of native oxide or metal oxide on the surface of the metal electrode and the dielectric layer, high leakage current will be caused (large leakage current) And the Unstabu voltage coefficient (Vc), which causes capacitance variation (capacitance variation) and makes capacitor performance not as expected at design time. Therefore, it is necessary to remove these oxides to improve capacitor performance. 5-3 Invention Purpose and summary The main object of the present invention is to provide a method for forming a capacitor, including an oxygen plasma cleaning process step, to process the original oxide or metal oxide on the surface of the metal electrode and the dielectric layer. The leakage current can be reduced and a stable voltage coefficient can be obtained. According to the above-mentioned object, the present invention provides a method for forming a capacitor, which includes the following steps. First, a first conductor layer is formed on a substrate to form a lower electrode of the capacitor. Secondly, the surface of the lower electrode was cleaned with 02 + cf4 plasma. Then a dielectric layer was formed for cleaning Above the lower electrode, and then cleaning the surface of the dielectric layer with 〇2 + CF4 plasma. Finally, a second conductor layer is formed to cover the cleaned dielectric layer to serve as the upper electrode of the capacitor, forming the capacitor of the method. In another embodiment provided by this statement, the method for forming a capacitor includes the following steps. First, a first conductor layer is formed on a substrate. Then,

Page 5 447120 V. Description of the invention (3) Define the pattern and etch the first conductor layer to form the lower electrode of the capacitor. The surface of the lower electrode was then washed with a 02 + CF4 plasma. Next, a dielectric layer is formed on the cleaned lower electrode. Then, the surface of the dielectric layer was cleaned with 0 2 + cf4 plasma. After that, a second conductor layer is formed to cover the washed dielectric layer. Finally, a pattern is defined and the second conductor layer is etched to serve as an electrode above the capacitor. That is, the capacitor of this method is formed. '5-4 Detailed Description of the Invention: Preferred embodiments of the present invention will be discussed in detail later. This embodiment is used to describe a specific example of using the present invention, and is not intended to limit the scope of the present invention. In the following description, 'Although it describes the method of manufacturing a single capacitor', it is clear that it is also possible to manufacture a plurality of capacitors on a substrate at the same time. In this invention, the kind of the substrate is not limited. Suitable semiconductor substrates can be used. In general, silicon semiconductors are used. There is no other way to form electrodes or dielectric layers in the valley device. The cleaning step can be performed by oxygen plasma method (oxygen plasma), and is performed by using a gas mixture of oxygen and carbon tetrafluoride (or plasma). U2 + CF4 according to the present invention-Example ’This method includes the following steps, as shown in the figure-’ Provide a substrate 10, possible substrates to :: First can be ~

Page 6 ^ 4471 2 〇 V. Description of the invention (4) ---- Silicon substrate 'then a first conductor layer is formed on the substrate 10 as the capacitor 1 electrode 20' offending conductor layer can be at least Inscription, copper, flip, silver, gold, or, network. Next, as shown in the second figure, a cleaning step is performed on the surface of the lower electrode 20. The cleaning step is performed using an oxygen and carbon tetrafluoride plasma (〇2 + CF4 pUsma) method, where the pressure used is about 1 ~ 5 Torr (Torr), and the plasma power source is about 80Ό ~ looo. Watt, the temperature is about 2000 ~ 300, it, the oxygen flow rate is about 2500 ~ 3500 sccm 'carbon tetrafluoride is about 20 ~ 100 sccm, and the time is about 10 ~ 30 seconds. Then, as shown in the third figure, a dielectric layer 30 is formed on the surface of the cleaned lower electrode 20. The possible dielectric layer can be at least two pentoxides.

Ta2 05, barium strontium titanate 'BST, lead zirconium titanate (PZT), oxide-nitride-oxide (ONO), silicon nitride, silicon oxynitride or silicon dioxide . Then, a cleaning step is performed on the surface of the dielectric layer 30. Finally, as shown in the fourth figure, 'the second conductor layer 40 is formed to cover the cleaned dielectric layer 30 as an electrode on the capacitor', so that a capacitor is formed. The substance that may be used as the upper electrode contains at least TiN »According to another embodiment of the present invention, the following steps are included: First, as shown in FIG. 5), a substrate 10 ′ is provided. The possible substrate can be at least one The substrate is then formed, and then a first conductor layer 50 is formed on the substrate 10, and then a pattern is defined to etch the first conductor layer to form the lower electrode 12 of the capacitor. A possible conductor layer that can be used as the lower electrode of the electrical device is as described in the previous embodiment. Next as the sixth

Page 7 447 彳 2 〇 5. Description of the invention (5) As shown in the figure, the surface of the lower electrode 50 is cleaned with 02 + CF4 plasma. Next, as shown in FIG. 7, a dielectric layer 60 is formed on the surface of the lower electrode 50 which has been cleaned. Possible dielectric layers can be at least two groups of pentoxide Ta205, BST, PZT, oxide-nitride-oxide (ONO), nitrided nitride, oxynitride, or silicon dioxide. Then, a cleaning step is performed on the surface of the dielectric layer 60. Then, as shown in the eighth figure, "the second conductor layer 70 is formed to cover the surface of the cleaned dielectric layer 60". Finally, a pattern is defined and engraved to form an electrode on the capacitor. However, the substance as the second electrode includes at least T i Ν. This forms a capacitor. The above are merely preferred embodiments of the present invention, and are not intended to limit the scope of patent application for the present invention; all other equivalent changes or modifications made without departing from the spirit disclosed by the present invention shall be included in the following Within the patent application park.

447120 Brief description of the drawings As shown in the drawings of this description: The first to fourth figures are cross-sectional views of a preferred embodiment of the present invention. The fifth to eighth figures are cross-sectional illustrations of another preferred embodiment of the present invention. 0 The representative symbols of the main parts: 10 substrate 20 first conductor layer 30 dielectric layer 40 second conductor layer 50 first conductor layer 60 Dielectric layer 70 Second conductor layer

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Claims (1)

447120 VI. _Please Patent Scope '---------- 1. A method for forming a capacitor, the method includes at least the following steps: providing a semiconductor substrate; an electrode forming a first conductor layer on the substrate, Cleaning the surface of the first conductor layer with an oxygen-containing plasma to form a capacitor; forming a dielectric layer to cover the surface of the lower electrode that has been cleaned; 'cleaning the surface of the dielectric layer using the oxygen-containing plasma; and A second conductor layer is formed to cover the cleaned dielectric layer to form the + -upper electrode of the capacitor. 2. The method of claim 1, wherein the first conductor layer is a metal layer. 3. The method according to item 2 of the scope of patent application, wherein the metal layer is one selected from the group consisting of aluminum, steel, platinum, gold, silver, and chromium. 4. The method of claim 1 in which the first-conductor layer is a polycrystalline dream layer. 5. The method according to item 1 of the scope of patent application, wherein the dielectric layer is selected from the group consisting of pentoxide, BST, ρζτ, oxide-nitride ~ oxide (0N0) 447120 VI. Scope of Patent Application 6. The method of claim 1, wherein the second conductor layer is a metal layer. Alas, as in the method of applying for the first item of the patent scope, wherein the second conductor layer is a titanium oxide layer D 8 'As in the method of applying for the first item of the patent scope, wherein the oxygen-containing plasma is used to clean the first conductor layer Surface step and cleaning the surface of the dielectric layer are carried out with an oxygen plasma. 9. The method according to item 1 of the scope of patent application, wherein the step of cleaning the surface of the first conductor layer with the oxygen-containing plasma and cleaning the dielectric layer The surface step is performed by a plasma of oxygen and carbon tetrafluoride mixed gas. I 0. The method according to item 9 of the scope of patent application, wherein the pressure used in the cleaning step is about 1 to 5 Torr, the plasma power source is about 800 to 1000 watts, and the temperature is about 200 to 300 ° C, the radon flow rate is about 2500 ~ 3500 seem, carbon tetrafluoride is about 20 ~ 100seem, and the time is about 10 ~ 30 seconds. II A method of forming a capacitor, the method comprising at least the following steps: providing a semiconductor substrate; Page 11 447120 VI. Scope of patent application: forming a first conductor layer on the substrate; defining a pattern on the first conductor layer; etching the first conductor layer to form a lower electrode of a capacitor; An oxygen-containing plasma is used to clean the surface of the first conductor layer; a dielectric layer is formed to cover the surface of the lower electrode that has been washed; an oxygen-containing plasma is used to clean the surface of the dielectric layer; a second conductor layer is formed to cover the cleaned one The dielectric layer defines a pattern on the second conductor layer; and the second conductor layer is engraved to form an upper electrode of the capacitor. 12. The method according to claim 11 of the scope of patent application, wherein the first conductor layer is a metal layer. 13. The method according to item 12 of the scope of patent application, wherein the metal layer is selected from one of the materials consisting of steel, steel, gold, silver, and chromium. 14 The method of item 'wherein the first conductor layer is a polycrystalline dream layer. 15. The method according to claim 11 of the patent application scope, wherein the dielectric layer is selected from the group consisting of pentoxide, BST, PZT, oxide-nitride-oxide (0N0), silicon nitride, and silicon oxynitride And silicon dioxide is one of the group of materials. 447120 6. Scope of applying for patent 16. The method according to item u of the scope of applying for patent, wherein the second conductor layer is a metal layer. 17. The method of claim π, wherein the second conductor layer is a nitrided layer. 18. The method according to item 11 of the application, wherein the step of cleaning the surface of the first conductor layer using the oxygen-containing plasma and the step of cleaning the surface of the dielectric layer are performed using an oxygen plasma. 19. The method of claim 11 in the scope of patent application, wherein the step of cleaning the surface of the first conductor layer using the oxygen-containing plasma and the step of cleaning the surface of the dielectric layer are performed with a plasma of oxygen and carbon tetrafluoride mixed gas. 20. The method according to item 19 of the scope of patent application, wherein the pressure used in the cleaning step is about 1 ~ 5 Torr, the plasma power is about 800 ~ 1000 Watt, and the temperature is about 200 ~ 300 ° C. The oxygen flow rate is about 2500 ~ 3500sccm, carbon tetrafluoride is about 20 ~ 100sccm, and the time is about 10 ~ 30 seconds.