Power transistor device having ultra deep increased concentration region
First Claim
1. A method of manufacture of a power semiconductor device comprising the steps of:
- forming an oxide layer on a surface of a semiconductor chip which is of a first conductivity type;
forming a first window mask on a surface of said oxide layer, etching a portion of said oxide layer that is exposed by said first window mask to form thin oxide regions, applying carriers of said first conductivity type to said chip through said thin oxide regions and diffusing said carriers to a first depth into said substrate to form increased conduction regions;
the side boundaries of said increased conduction regions side diffusing toward one another to boundary positions which are at least close to one another;
forming a second window mask which overlies and is centered on the boundaries between said increased conduction regions and then applying a first given concentration of carriers of a second conductivity type to said chip surface through said second window mask;
forming a thin gate dielectric and a conductive gate electrode over at least portions of the surface of said increased conduction regions;
forming a third window mask which surrounds and is at least adjacent to the locations of respective ones of said second window mask and then applying a second given concentration of carriers of the second conductivity type, which is less than said first given concentration, to said chip through said third window mask;
diffusing said carriers of said first and second given concentrations of said second conductivity type to their final depths which are less than the final depth of said increased conduction regions of the first conductivity type, with said carriers of said first given concentration forming a body of high concentration and said carriers of said second given concentration forming a low concentration channel region which surrounds said body of high concentration and underlies said thin gate dielectric;
applying a high concentration of carriers of said first conductivity type through said third window mask and diffusing them to form shallow source regions which diffuse laterally to underlie said thin gate dielectric and bounds the inner edge of said low concentration channel region; and
forming a source electrode on said source regions and a drain electrode which is electrically connected to said chip.
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Accused Products
Abstract
A cellular insulated gate bipolar transistor ("IGBT") device employs increased concentration in the active region between spaced bases to a depth greater than the depth of the base regions. The implant dose which is the source of the increased concentration is about 3.5×1012 atoms per centimeter squared and is driven for about 10 hours at 1175° C. Lifetime is reduced by an increased radiation dose to reduce switching loss without reducing breakdown voltage or increasing forward voltage, drop above previous levels. The increased concentration region permits a reduction in the spacing between bases and provides a region of low localized bipolar gain, increasing the device latch current. The avalanche energy which the device can successfully absorb while turning off an inductive load is significantly increased. The very deep increased conduction region is formed before the body and source regions in a novel process for making the new junction pattern.
48 Citations
21 Claims
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1. A method of manufacture of a power semiconductor device comprising the steps of:
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forming an oxide layer on a surface of a semiconductor chip which is of a first conductivity type; forming a first window mask on a surface of said oxide layer, etching a portion of said oxide layer that is exposed by said first window mask to form thin oxide regions, applying carriers of said first conductivity type to said chip through said thin oxide regions and diffusing said carriers to a first depth into said substrate to form increased conduction regions;
the side boundaries of said increased conduction regions side diffusing toward one another to boundary positions which are at least close to one another;forming a second window mask which overlies and is centered on the boundaries between said increased conduction regions and then applying a first given concentration of carriers of a second conductivity type to said chip surface through said second window mask; forming a thin gate dielectric and a conductive gate electrode over at least portions of the surface of said increased conduction regions; forming a third window mask which surrounds and is at least adjacent to the locations of respective ones of said second window mask and then applying a second given concentration of carriers of the second conductivity type, which is less than said first given concentration, to said chip through said third window mask; diffusing said carriers of said first and second given concentrations of said second conductivity type to their final depths which are less than the final depth of said increased conduction regions of the first conductivity type, with said carriers of said first given concentration forming a body of high concentration and said carriers of said second given concentration forming a low concentration channel region which surrounds said body of high concentration and underlies said thin gate dielectric; applying a high concentration of carriers of said first conductivity type through said third window mask and diffusing them to form shallow source regions which diffuse laterally to underlie said thin gate dielectric and bounds the inner edge of said low concentration channel region; and forming a source electrode on said source regions and a drain electrode which is electrically connected to said chip. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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14. A method of manufacture of a power semiconductor device comprising the steps of:
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forming a first window mask on a surface of a semiconductor chip which is of a first conductivity type and applying carriers of said first conductivity type to the exposed surface of said chip through said first window mask and then diffusing said carriers to a first depth into said substrate to form increased conduction regions;
the side boundaries of said increased conduction regions side diffusing toward one another to boundary positions which are at least close to one another;forming a second window mask which overlies and is centered on the boundaries between said increased conduction regions and then applying a first given concentration of carriers of a second conductivity type to said chip surface through said second window mask; forming a thin gate dielectric and a conductive gate electrode over at least portions of the surface of said increased conduction regions; forming, atop said thin gate dielectric, a third window mask which surrounds and is at least adjacent to the locations of respective ones of said second window mask and applying a second given concentration of carriers of the second conductivity type, which is less than said first given concentration, to said chip through said third window mask and through said thin gate dielectric; diffusing said carriers of said first and second given concentrations of said second conductivity type to their final depths which are less than the final depth of said increased conduction regions of the first conductivity type, with said carriers of said first given concentration forming a body of high concentration and said carriers of said second given concentration forming a low concentration channel region which surrounds said body of high concentration and underlies said thin gate dielectric; applying a high concentration of carriers of said first conductivity type through said third window mask and diffusing them to form shallow source regions which diffuse laterally to underlie said thin gate dielectric and bounds the inner edge of said low concentration channel region; and forming a source electrode on said source regions and a drain electrode which is electrically connected to said chip. - View Dependent Claims (15, 16, 17, 18, 19, 20, 21)
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Specification