Method for making a semiconductor device comprising a stack alternately consisting of silicon layers and dielectric material layers
First Claim
1. A method of fabricating a semiconductor device, the method comprising:
- forming on a main surface of a silicon substrate, a stack comprising successively at least one first combination and one second combination, wherein each combination comprises, with reference to the substrate, a thin bottom layer of germanium, or a germanium and silicon alloy (SiGe), and a thin top layer of silicon;
forming on the thin top silicon layer of the second combination, a thin silicon dioxide layer that supports the layers of the stack on at least two opposite lateral sides of the stack;
forming a hard mask on the thin silicon dioxide layer so as to form two separate opposed areas on respective opposite sides of two opposite edges of the hard mask;
etching the thin silicon dioxide layer, the top silicon layer and at least part of the lower germanium or SiGe layer of the second combination in the two separate opposed areas;
selectively laterally etching the bottom germanium or SiGe layer of the second combination to form a tunnel;
thermally oxidizing the tunnel of the second combination;
etching the top silicon layer and at least part of the bottom germanium or SiGe layer of the first combination in the two separate opposed areas; and
selectively laterally etching the bottom germanium or SiGe layer of the first combination to form a tunnel.
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Accused Products
Abstract
A method of fabricating a semiconductor device consisting of a silicon substrate on which is formed a stack of layers is described. The stack may have successively at least one first and one second combination. Each combination may consist, with reference to the substrate, of a thin bottom SiGe layer and a thin top silicon layer. A thin silicon dioxide film (18) is formed on the thin top silicon layer of the second combination so that the layer concerned supports the layers of the stack on at least two opposite lateral sides of the stack. Successive selective lateral etching of the SiGe layers is then carried out to form tunnels which are filled with a dielectric material.
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Citations
11 Claims
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1. A method of fabricating a semiconductor device, the method comprising:
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forming on a main surface of a silicon substrate, a stack comprising successively at least one first combination and one second combination, wherein each combination comprises, with reference to the substrate, a thin bottom layer of germanium, or a germanium and silicon alloy (SiGe), and a thin top layer of silicon;
forming on the thin top silicon layer of the second combination, a thin silicon dioxide layer that supports the layers of the stack on at least two opposite lateral sides of the stack;
forming a hard mask on the thin silicon dioxide layer so as to form two separate opposed areas on respective opposite sides of two opposite edges of the hard mask;
etching the thin silicon dioxide layer, the top silicon layer and at least part of the lower germanium or SiGe layer of the second combination in the two separate opposed areas;
selectively laterally etching the bottom germanium or SiGe layer of the second combination to form a tunnel;
thermally oxidizing the tunnel of the second combination;
etching the top silicon layer and at least part of the bottom germanium or SiGe layer of the first combination in the two separate opposed areas; and
selectively laterally etching the bottom germanium or SiGe layer of the first combination to form a tunnel. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A method of fabricating a semiconductor device, the method comprising:
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forming on a main surface of a silicon substrate, a stack comprising successively at least one first combination and one second combination, wherein each combination comprises, with reference to the substrate, a thin bottom layer of germanium, or a germanium and silicon alloy (SiGe), and a thin top layer of silicon;
forming on the thin top silicon layer of the second combination, a thin silicon dioxide layer that supports the layers of the stack on at least two opposite lateral sides of the stack;
forming a hard mask on the thin silicon dioxide layer so as to form two separate opposed areas on respective opposite sides of two opposite edges of the hard mask;
etching the thin silicon dioxide layer, the top silicon layer and at least part of the lower germanium or SiGe layer of the second combination in the two separate opposed areas;
selectively laterally etching the bottom germanium or SiGe layer of the second combination to form a tunnel;
thermally oxidizing the tunnel of the second combination;
etching the top silicon layer and at least part of the bottom germanium or SiGe layer of the first combination in the two separate opposed areas;
selectively laterally etching the bottom germanium or SiGe layer of the first combination to form a tunnel; and
filling the tunnel of the first combination with a solid dielectric material. - View Dependent Claims (10, 11)
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Specification