Method and apparatus for etching Si
a technology of etching method and etching rate, which is applied in the direction of electrical apparatus, electric discharge tubes, basic electric elements, etc., can solve the problems of poor processing efficiency, low etching rate, and incompatibility of mix gas with dti, and achieve high etching rate, high etching rate, and high reaction possibility
Inactive Publication Date: 2006-02-02
TOKYO ELECTRON LTD
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- Application Information
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Benefits of technology
The present invention provides a method and apparatus for etching silicon using a mixture gas of Cl2, O2, and NF3 with a specific residence time of at least 180 msec. The etching gas is supplied to the chamber at a gas inlet pressure of at least 60 mtorr and an effective volume of etching space of at least 100 μm. The etching gas is a mixture of Cl2, O2, and NF3 with a ratio of O2 to Cl2 and NF3 of 0.1-0.3. The etching gas can be mixed with an inert gas such as Ar as a diluent gas, and the total flow rate of the etching gas should be equal to or less than about 100 sccm. The etching pressure should range from about 20 mtorr to about 2000 mtorr, and the distance between electrodes should range from about 30 mm to about 300 mm. The invention allows for a high etching rate with a high aspect ratio of the etched structure.
Problems solved by technology
However, the deep trench with a high aspect ratio cannot be formed with the mixture gas of HBr and O2 and thus this mixture gas is not compatible with the DTI.
Moreover, this mixture gas presents a several drawbacks such as a low etching rate and thus a poor processing efficiency and a low productivity.
Method used
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Examples
Experimental program
Comparison scheme
Effect test
examples 1 to 8
[0045] Trench etchings for forming a trench for DTI, which has an opening width of about 0.3 μm and a depth of about 3 to about 6 μm, were performed by using the plasma etching apparatus shown in FIG. 1 while varying gas flow rates of Cl2, O2 and NF3 included in the etching gas and ratios of flow rates thereof. FIGS. 3 and 4 show the resultant data obtained from the examples 1 to 8. The other major etching conditions are as follows: [0046] Diameter of the Si wafer; 200 mm [0047] Mask made of two material layers; [0048] upper layer—SiO2 layer of 3000 Å[0049] lower layer—SiN layer of 1500 Å[0050] Pressure; 60 mtorr [0051] RF power (upper electrode / lower electrode); 500 W / 600 W [0052] Electrode gap; 115 mm [0053] Temperature (upper electrode / lower electrode / chamber sidewall); 80° C. / 60° C. / 60° C.
[0054] Comparative examples of etching DTI in Si also have been carried out for comparison.
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Abstract
A method for dry-etching a Si substrate or a Si layer in a processing chamber includes the step of supplying an etching gas into the processing chamber, wherein the etching gas is a mixture gas including Cl2, O2 and NF3 and a residence time τ of the etching gas is equal to or greater than about 180 msec, the residence time τ being defined as: τ=pV / Q where p represents an inner pressure of the processing chamber; V, an effective volume of etching space formed on the Si substrate or the Si layer; and Q, a flow rate of the etching gas.
Description
FIELD OF THE INVENTION [0001] The present invention relates to a method and apparatus for etching Si (silicon); and, more particularly, to a method and an apparatus for forming a trench with a narrow width and a deep depth in a Si substrate or a Si layer. BACKGROUND OF THE INVENTION [0002] A shallow trench isolation (STI) scheme is widely used in the manufacture of LSI (large scale integrated) circuits to isolate devices or elements thereof. The STI generally includes the step of dry-etching in a Si substrate a relatively shallow trench (or groove) having a depth of 1 μm or less by using a photoresist or an insulating layer as a mask. Such a trench etching requires a technique to control a trench depth and a trench profile, especially a sidewall angle (taper angle). [0003] Conventionally, a Br(bromine)-based mixture gas, typically a mixture gas of HBr and O2, is widely used as an etching gas for the STI procedure. HBr is a relatively less reactive with an oxide layer (SiO2) formed b...
Claims
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IPC IPC(8): C23F1/00H01L21/302H01L21/3065H01L21/306H01L21/461
CPCH01L21/3065H01J37/32082H01L21/306
Inventor SAITA, YOSHITAKAYAMAGUCHI, MASASHI
Owner TOKYO ELECTRON LTD