High-frequency wireless communication system on a single ultrathin silicon on sapphire chip
First Claim
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1. A method of fabricating a semiconductor substrate structure comprising the steps of:
- (a) forming a substantially monocrystalline silicon layer on an electrically insulating substrate;
(b) implanting ions in the silicon layer to amorphorize an inner portion of the silicon layer adjacent to the substrate while maintaining an outer portion of the silicon layer substantially monocrystalline;
(c) annealing the silicon layer in an inert ambient for causing solid phase epitaxial regrowth of the inner portion from the outer portion by ramping a temperature of the silicon layer upwardly from an initial value; and
(d) displacing the inert ambient with an oxidizing ambient and exposing the silicon layer to the oxidizing ambient for surface oxidation thereof when the temperature of the silicon layer reaches a first predetermined value, thereby forming a first surface layer of oxidized silicon, and subsequently increasing the temperature of the silicon layer to a second predetermined value.
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Abstract
A high-frequency wireless communication system on a single ultrathin silicon on sapphire chip is presented. This system incorporates analog, digital (logic and memory) and high radio frequency circuits on a single ultrathin silicon on sapphire chip. The devices are fabricated using conventional bulk silicon CMOS processing techniques. Advantages include single chip architecture, superior high frequency performance, low power consumption and cost effective fabrication.
134 Citations
18 Claims
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1. A method of fabricating a semiconductor substrate structure comprising the steps of:
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(a) forming a substantially monocrystalline silicon layer on an electrically insulating substrate; (b) implanting ions in the silicon layer to amorphorize an inner portion of the silicon layer adjacent to the substrate while maintaining an outer portion of the silicon layer substantially monocrystalline; (c) annealing the silicon layer in an inert ambient for causing solid phase epitaxial regrowth of the inner portion from the outer portion by ramping a temperature of the silicon layer upwardly from an initial value; and (d) displacing the inert ambient with an oxidizing ambient and exposing the silicon layer to the oxidizing ambient for surface oxidation thereof when the temperature of the silicon layer reaches a first predetermined value, thereby forming a first surface layer of oxidized silicon, and subsequently increasing the temperature of the silicon layer to a second predetermined value. - View Dependent Claims (2, 3)
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4. A method of fabricating a semiconductor substrate structure comprising the steps of:
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(a) forming a substantially monocrystalline silicon layer on a surface of an electrically insulating substrate; (b) implanting ions in the silicon layer to form an amorphous region in the silicon layer near the surface of the insulating substrate while leaving substantially monocrystalline silicon in another region of the silicon layer which is adjacent to the amorphous region; (c) annealing the silicon layer in an inert ambient to cause solid phase epitaxial regrowth of the amorphous region; (d) displacing the inert ambient with an oxidizing ambient and exposing the silicon layer to the oxidizing ambient for surface oxidation thereof thereby forming a first surface layer of oxidized silicon; (e) removing the first surface layer of oxidized silicon by etching; (f) oxidizing the silicon layer a second time to form a second surface layer of oxidized silicon; and (g) removing the second surface layer of oxidized silicon by etching.
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5. A method of fabricating a silicon on sapphire wafer having an intrinsic silicon layer on a sapphire substrate, said method comprising the steps of:
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epitaxially depositing a layer of silicon on a surface of a sapphire substrate; implanting a given ion species into said layer of silicon under such conditions that said implanted ions form a buried amorphous region in said silicon layer which extends substantially from said surface of said sapphire substrate into said layer of silicon, thus leaving a surface layer of monocrystalline silicon covering said buried amorphous region; maintaining said layer of silicon at or below a temperature of approximately zero degrees centigrade (0°
C.) such that said temperature is substantially uniform throughout said layer of silicon during said ion implanting step;annealing the wafer to induce solid phase epitaxial regrowth of said buried amorphous region using said surface layer of monocrystalline silicon as a crystallization seed; oxidizing said layer of silicon by exposure to an oxidizing ambient for surface oxidation thereof thereby forming a first surface layer of oxidized silicon; removing said first surface layer of oxidized silicon; oxidizing said layer of silicon a second time to form a second surface layer of oxidized silicon; and removing said second surface layer of oxidized silicon. - View Dependent Claims (6, 7, 8, 9, 10, 11, 12, 13, 14, 15)
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16. A method of fabricating a silicon on sapphire wafer having an intrinsic silicon layer on a sapphire substrate, said method comprising the steps of:
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epitaxially depositing a layer of silicon on a surface of a sapphire substrate; positioning said sapphire substrate adjacent a chamber through which flows a coolant such that said coolant contacts said sapphire substrate; implanting a given ion species into said layer of silicon under such conditions that said implanted ions form a buried amorphous region in said silicon layer which extends substantially from said surface of said sapphire substrate into said layer of silicon, thus leaving a surface layer of monocrystalline silicon covering said buried amorphous region; controlling the flow rate or the temperature or both the flow rate and the temperature of said coolant through said chamber to maintain said layer of silicon substantially at or below a temperature of approximately zero degrees centigrade (0°
C.) during said ion implanting step;annealing the wafer to induce solid phase epitaxial regrowth of said buried amorphous region using said surface layer of monocrystalline silicon as a crystallization seed; oxidizing said silicon layer by exposure to an oxidizing ambient for surface oxidation thereof thereby forming a first surface layer of oxidized silicon; removing said first surface layer of oxidized silicon; oxidizing said silicon layer a second time to form a second surface layer of oxidized silicon; and removing said second surface layer of oxidized silicon. - View Dependent Claims (17, 18)
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Specification