Method for manufacturing thin film capacitor with anodic oxidation film as dielectric layer

An anodized film, film capacitor technology, applied in capacitor manufacturing, capacitors, circuits, etc., can solve the problems of complex production process of air bridge, complex equipment and process, poor film compactness, etc., to achieve capacitance value and withstand voltage value The effect of easy adjustment of size, good electrical properties, and low manufacturing cost

Active Publication Date: 2015-02-04
CHINA ELECTRONIS TECH INSTR CO LTD
5 Cites 6 Cited by

AI-Extracted Technical Summary

Problems solved by technology

The disadvantage of this manufacturing process is that in addition to physical vapor deposition coating equipment, large and expensive equipment such as plasma chemical vapor deposition and dry etching are required, and a complex manufacturing process for air bridges is required.
For example, it is mentioned in the published patent CN 1295341A: adopt low-pressure chemical vapor deposition (LPCVD) to obtain amorphous Ta 2 o 5 thin film, however this amorphous Ta 2 o 5 The compactne...
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Method used

In the design of the present invention, first etch out lower electrode and the first lower electrode lead-out line, adopt photolithography process to make photoresist mask and protect the first lower electrode lead-out line, lower electrode is carried out in acid electrolyte Anodic oxidation, a dense insulating layer is grown on the surface and side of the lower electrode at the same time, and the insulating layer grown by anodic oxidation on the side of the lower electrode edge naturally forms a dielectric bridge, so that when the lead-out line of the upper electrode passes through the edge of the lower electrode, there is no need to Special treatment greatly simplifies the manufacturing process.
The electrolytic solution of anodic oxidation adopts acid...
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Abstract

The invention discloses a method for manufacturing a thin film capacitor with an anodic oxidation film as a dielectric layer. The method comprises the following steps: a substrate is prepared, and a layer of metal or metal oxide thin film is deposited on the substrate; the thin film is patterned by a photolithography and etching process to form a lower electrode and a first lower electrode lead-out wire; photoresist is applied to the lower electrode and the first lower electrode lead-out wire, and an anodic oxidation mask is formed through a photolithography process; anode oxidation is carried out on the lower electrode to form a dielectric layer; and the photoresist is removed, an electrode layer is deposited on the substrate, and the electrode layer is patterned by a photolithography and etching process to form a second lower electrode lead-out wire, an upper electrode, and an upper electrode lead-out wire. Manufacturing equipment and processes needed by the method are simple, the manufacturing cost is low, the capacitance value and voltage value are easy to adjust, and excellent electrical characteristics are achieved.

Application Domain

Capacitor manufacture

Technology Topic

Film capacitorPhotoresist +6

Image

  • Method for manufacturing thin film capacitor with anodic oxidation film as dielectric layer
  • Method for manufacturing thin film capacitor with anodic oxidation film as dielectric layer
  • Method for manufacturing thin film capacitor with anodic oxidation film as dielectric layer

Examples

  • Experimental program(1)

Example Embodiment

[0056] Example one:
[0057] On a sapphire substrate 1 with a thickness of 0.254 mm, a Ta film is deposited as a metal film 2 by magnetron sputtering. The thickness of the Ta film is about 300 nm, such as figure 1 Shown.
[0058] The metal thin film 2 is patterned by a photolithography etching process to form a lower electrode 202 and a first lower electrode lead line 201, such as figure 2 Shown. Among them, Ta etchant uses HF buffer.
[0059] A photoresist is spin-coated on the lower electrode 202 and the first lower electrode lead-out line 201, and an anodic oxidation mask is formed through a photolithography process. The thickness of the patterned anodic oxidation mask 3 is 8 microns. The anodizing mask 3 completely covers the first lower electrode lead-out line 201 to prevent the first lower electrode lead-out line 201 from being oxidized during anodization. The opening area of ​​the anodizing mask 3 is larger than that of the lower electrode 202, so that the side surface of the lower electrode 202 is also exposed. The positive pole of the DC stabilized current power supply is connected to the bottom electrode 202 as the anode through the first bottom electrode lead wire 201, and the negative pole of the power supply is connected to the steel plate as the cathode, soaked in the electrolyte. The composition of the electrolyte is oxalic acid: water: ethylene glycol = 1: 2:3 (weight ratio), temperature 25°C. Anodizing is carried out by using constant current first and then constant voltage. Set the current according to the area of ​​anodization, that is, the area of ​​the lower electrode 202, so that the current density is 1mA/mm 2 , The oxidation voltage is set to 180V. After being energized, the portion of the bottom electrode 202 in contact with the electrolyte undergoes an oxidation reaction to generate metal oxide Ta 2 O 5 At the beginning of the electrolysis reaction, the lower electrode 202 has better conductivity and lower access resistance, so the voltage is lower. As the electrolysis reaction time increases, an oxide film grows on the surface of the lower electrode 202, and the resistance gradually increases, so the voltage also gradually increases. When the voltage increases to the set voltage of 180V, the oxidation reaction continues, the access resistance continues to increase, and the current gradually decreases, when the current density decreases to 2μA/mm 2 Stop anodizing at the time. A dielectric layer 4 is formed on the surface (including the side surface) of the lower electrode 202. The thickness of the dielectric layer 4 is about 320nm (1.78*180=320.4), and the thickness of the consumed Ta film is 128nm (0.4*320.4=128.2). The dielectric layer 4 The thickness of the unoxidized Ta film below is about 171.8nm (300-128.2=171.8), such as image 3 Shown.
[0060] Remove the anodic oxidation mask 3, and deposit TiW-Au multilayer metal film as the electrode layer 5 by magnetron sputtering on the substrate 1 that already contains the circuit pattern. TiW is used as an adhesion layer to increase the Au layer and the substrate. The adhesion between the sheets 1, the thickness of the TiW layer is about 50nm, and the thickness of the Au layer is about 200nm, such as Figure 4 Shown.
[0061] The electrode layer 5 is patterned by a photolithography etching process to form a second lower electrode lead-out line 501, an upper electrode 503, and an upper electrode lead-out line 502, such as Figure 5 Shown. Among them, the TiW layer is etched with hydrogen peroxide, and the Au layer is etched with iodine and potassium iodide solutions.

PUM

PropertyMeasurementUnit
Thickness50.0 ~ 500.0nm
Thickness1.0 ~ 30.0µm

Description & Claims & Application Information

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