Structure of semiconductor metal capacitor and etching method

Abstract

The structure of semiconductor alloy capacitance includes lower electrode, dielectric layer and upper electrode in sequence from lower to upper. The dielectric layer includes an oxide film layer, an ammoniated film layer, and another oxide film layer from lower to upper. Using multiple dielectric layers, the structure makes semiconductor alloy capacitance possible to reserve each advantage of oxide film layer, and ammoniated film layer, and overcome disadvantage of small dielectric coefficients of the film layers, and lot of pinholes on the film layers. The invention also discloses method for etching the capacitance. After etching out upper electrode, and using condition of selection ration in high etching speed, the method etches out uppermost oxide film layer, and stops etching operation when the ammoniated film layer is met. Advantages are: easy of implementation, large technical window for etching time, even thickness of dielectric layer, and raised quality and efficiency.

Description

technical field [0001] The invention relates to a structure of a capacitor, in particular to a structure of a semiconductor metal capacitor; the invention also relates to an etching method of a semiconductor metal capacitor. Background technique [0002] In the process of semiconductor manufacturing, it is often necessary to grow a dielectric layer and a titanium nitride metal film on the metal aluminum line to form a metal capacitor. Metal capacitors require specific etching procedures to give them the desired shape. The structure of metal capacitors before etching can be found in figure 1 . The lowermost layer is a metal layer 7 of titanium / titanium nitride, above which there is a metal layer 6 of metal aluminum, and a layer of metal layer 5 of titanium / titanium nitride is further formed on the top of the metal aluminum layer 6. The above three layers 5, 6 , 7 jointly form the lower electrode 4 of the metal capacitor. On the lower electrode 4 is a dielectric layer 3 as...

AI Technical Summary

Problems solved by technology

The oxide film has good film quality and less pinholes, but the dielectric coefficient is small, only about 4, which cannot achieve large-capacity capacitance; the nitride film has a large dielectric coefficient, which can reach 7.8, and is more commonly used

However, there are many pinholes in the nitride film, which is easy to cause leakage

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