Method to fabricate a highly perforated silicon diaphragm with controlable thickness and low stress
First Claim
1. A method of fabricating a perforated silicon diaphragm comprising:
- providing a single crystal silicon substrate of a first conductivity type;
blanket implanting first ions of a second conductivity type opposite said first conductivity type into said single crystal silicon substrate to form an etch stop layer;
selectively implanting second ions of said first conductivity type into said single crystal silicon substrate to form a pattern of holes in a portion of said substrate;
implanting third ions of said first conductivity type overlying said pattern of holes and forming a first ohmic contact region;
implanting fourth ions of said second conductivity type not surrounding said pattern of holes to form a second ohmic contact region;
thereafter depositing a nitride layer on a frontside and a backside of said silicon substrate;
forming contacts through said nitride layer to said first and second ohmic contact regions;
thereafter patterning said backside nitride layer; and
from the backside, etching away said silicon substrate not covered by said nitride layer to said etch stop layer and simultaneously selectively etching away said pattern of holes to complete formation of said perforated diaphragm.
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Abstract
A method of fabricating a highly perforated silicon diaphragm is described. A single crystal silicon substrate of a first conductivity type is provided. First ions of a second conductivity type opposite the first conductivity type are implanted into the single crystal silicon substrate to form an etch stop layer. Second ions of the first conductivity type are selectively implanted into the single crystal silicon substrate to form a pattern of holes in a portion of the substrate. Third ions of the first conductivity type are implanted overlying the pattern of holes and forming a first ohmic contact region. Fourth ions of the second conductivity type are implanted into the substrate not surrounding the pattern of holes to form a second ohmic contact region. A nitride layer is deposited on a frontside and a backside of the silicon substrate. Contacts are formed through the nitride layer to the first and second ohmic contact regions. Thereafter, the backside nitride layer is patterned and from the backside, the silicon substrate not covered by the nitride layer is etched away to the etch stop layer and, simultaneously, the pattern of holes is selectively etched away to complete formation of a perforated diaphragm.
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Citations
25 Claims
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1. A method of fabricating a perforated silicon diaphragm comprising:
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providing a single crystal silicon substrate of a first conductivity type;
blanket implanting first ions of a second conductivity type opposite said first conductivity type into said single crystal silicon substrate to form an etch stop layer;
selectively implanting second ions of said first conductivity type into said single crystal silicon substrate to form a pattern of holes in a portion of said substrate;
implanting third ions of said first conductivity type overlying said pattern of holes and forming a first ohmic contact region;
implanting fourth ions of said second conductivity type not surrounding said pattern of holes to form a second ohmic contact region;
thereafter depositing a nitride layer on a frontside and a backside of said silicon substrate;
forming contacts through said nitride layer to said first and second ohmic contact regions;
thereafter patterning said backside nitride layer; and
from the backside, etching away said silicon substrate not covered by said nitride layer to said etch stop layer and simultaneously selectively etching away said pattern of holes to complete formation of said perforated diaphragm. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A method of fabricating a perforated silicon diaphragm comprising:
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providing a single crystal silicon substrate of a first conductivity type;
blanket implanting first ions of a second conductivity type opposite said first conductivity type into said single crystal silicon substrate to form an etch stop layer wherein a depth of said etch stop layer into said silicon substrate determines a thickness of said perforated diaphragm;
selectively implanting second ions of said first conductivity type into said single crystal silicon substrate to form a pattern of holes in a portion of said substrate;
implanting third ions of said first conductivity type overlying said pattern of holes and forming a first ohmic contact region;
implanting fourth ions of said second conductivity type not surrounding said pattern of holes to form a second ohmic contact region;
thereafter depositing a nitride layer on a frontside and a backside of said silicon substrate;
forming contacts through said nitride layer to said first and second ohmic contact regions;
thereafter patterning said backside nitride layer; and
from the backside, etching away said silicon substrate not covered by said nitride layer to said etch stop layer and simultaneously selectively etching away said pattern of holes to complete formation of said perforated diaphragm. - View Dependent Claims (10, 11, 12, 13, 14, 15, 16)
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17. A method of fabricating a perforated silicon diaphragm comprising:
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providing a single crystal silicon substrate of a first conductivity type;
blanket implanting at a first dose first ions of a second conductivity type opposite said first conductivity type into said single crystal silicon substrate to form an etch stop layer wherein a depth of said etch stop layer into said silicon substrate determines a thickness of said perforated diaphragm;
selectively implanting at a second dose second ions of said first conductivity type into said single crystal silicon substrate to form a pattern of holes in a portion of said substrate;
implanting at a third dose third ions of said first conductivity type overlying said pattern of holes and forming a first ohmic contact region;
implanting at a fourth dose fourth ions of said second conductivity type not surrounding said pattern of holes to form a second ohmic contact region;
thereafter depositing a nitride layer on a frontside and a backside of said silicon substrate;
forming contacts through said nitride layer to said first and second ohmic contact regions;
thereafter patterning said backside nitride layer; and
from the backside, etching away said silicon substrate not covered by said nitride layer to said etch stop layer and simultaneously selectively etching away said pattern of holes to complete formation of said perforated diaphragm. - View Dependent Claims (18, 19, 20, 21, 22, 23, 24, 25)
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Specification