US4983544A — Silicide bridge contact process

Claim 1

Independent Claim 166 words

A method of forming a bridge contact between silicon regions on a substrate that are separated by a first insulating region having a first lateral length, without forming a bridge contact between silicon regions on the substrate that are separated by other insulating regions that have lateral lengths that are greater than that of said first insulating region, comprising the steps of: forming a refractory metal layer on the substrate under conditions so that said metal layer has a grain shape in which lower portions of the grains have a lateral length that approximates the lateral length of said first insulating region; sintering the substrate under conditions that limit lateral silicon diffusion, so that a silicide is formed over all of said silicon regions and said first insulation region without forming a silicide over said other insulating regions; and exposing the substrate to an etchant that preferentially removes portions of said refractory metal that did not react to form said silicide, without appreciably removing said silicide.

Claim 2

Independent Claim 166 words

A method of forming a bridge contact between silicon regions on a substrate that are separated by a first insulating region having a first lateral length, without forming a bridge contact between silicon regions on the substrate that are separated by other insulating regions that have lateral lengths that are greater than that of said first insulating region, comprising the steps of: forming a refractory metal layer on the substrate under conditions so that said metal layer has a grain shape in which lower portions of the grains have a lateral length that approximates the lateral length of said first insulating region; sintering the substrate under conditions that limit lateral silicon diffusion, so that a silicide is formed over all of said silicon regions and said first insulation region without forming a silicide over said other insulating regions; and exposing the substrate to an etchant that preferentially removes portions of said refractory metal that did not react to form said silicide, without appreciably removing said silicide.

Claim 3

Dependent Claim 30 words

The method of forming a bridge contact as recited in claim 1, wherein said refractory metal is selected from the group consisting of titanium, tungsten, cobalt, molybdenum, nickel and tantalum.

Claim 4

Dependent Claim 18 words

The method of forming a bridge contact as recited in claim 1, wherein said refractory metal comprises titanium.

Claim 5

Dependent Claim 24 words

The method of forming a bridge contact as recited in claim 1, wherein said refractory metal is formed on the substrate by evaporation techniques.

Claim 6

Dependent Claim 25 words

The method of forming a bridge contact as recited in claim 4, wherein said refractory metal is evaporated from a plurality of offset evaporation sources.

Claim 7

Dependent Claim 22 words

The method of forming a bridge contact as recited in claim 1, wherein said refractory metal has a substantially columnar grain structure.

Claim 8

Dependent Claim 23 words

The method of forming a bridge contact as recited in claim 6, wherein said refractory metal has a minimal amount of matrix material.

Claim 9

Dependent Claim 27 words

The method of forming a bridge contact as recited in claim 3, wherein said titanium is formed on the substrate at a temperature of approximately 370° C.

Claim 10

Dependent Claim 21 words

The method of forming a bridge contact as recited in claim 1, wherein said substrate is sintered in a nitrogen ambient.

Claim 11

Dependent Claim 28 words

The method of forming a bridge contact as recited in claim 3, wherein said substrate is sintered at approximately 700° C. in a 95% nitrogen -5% hydrogen ambient.

Claim 12

Dependent Claim 26 words

The method of forming a bridge contact as recited in claim 1, wherein said etchant comprises a 10:1 mixture of hydrogen peroxide and sulfuric acid, respectively.

Claim 13

Dependent Claim 36 words

The method of forming a bridge contact as recited in claim 1, wherein said etchant comprises a 5:1:1 mixture of deionized water, 58% concentrated NH 4 OH, and 30% concentrated H 2 O 2 , respectively.

Claim 14

Independent Claim 169 words

A method of forming a silicide bridge contact between two relatively coplanar silicon regions on a substrate that are separated by an insulating region having a small lateral length, without forming a bridge contact between other silicon regions on the substrate that are separated by other insulating regions that have lateral lengths that are greater than the lateral length of the thin insulating layer, comprising the steps of: forming a layer of refractory metal on the substrate under conditions such that said refractory metal has a grain shape wherein bottom portions of the grains have a lateral length that approximates the lateral length of the thin insulating regions; sintering the substrate under conditions that limit the lateral formation of silicide, said refractory metal reacting with the substrate to form a silicide above said silicon regions and said thin insulating region without forming a silicide above said other insulating regions; and exposing the substrate to an etchant that preferentially removes remaining portions of said refractory metal without removing said silicide.

Claim 15

Independent Claim 169 words

A method of forming a silicide bridge contact between two relatively coplanar silicon regions on a substrate that are separated by an insulating region having a small lateral length, without forming a bridge contact between other silicon regions on the substrate that are separated by other insulating regions that have lateral lengths that are greater than the lateral length of the thin insulating layer, comprising the steps of: forming a layer of refractory metal on the substrate under conditions such that said refractory metal has a grain shape wherein bottom portions of the grains have a lateral length that approximates the lateral length of the thin insulating regions; sintering the substrate under conditions that limit the lateral formation of silicide, said refractory metal reacting with the substrate to form a silicide above said silicon regions and said thin insulating region without forming a silicide above said other insulating regions; and exposing the substrate to an etchant that preferentially removes remaining portions of said refractory metal without removing said silicide.

Claim 16

Dependent Claim 31 words

The method of forming a silicide bridge contact as recited in claim 13, wherein said refractory metal is selected from the group consisting of tungsten, titanium, cobalt, molybdenum, nickel and tantalum.

Claim 17

Dependent Claim 19 words

The method of forming a silicide bridge contact as recited in claim 13, wherein said refractory metal comprises titanium.

Claim 18

Dependent Claim 29 words

The method of forming a bridge contact as recited in claim 13, wherein said refractory metal has a substantially columnar grain structure and a minimal amount of matrix material.

Claim 19

Dependent Claim 28 words

The method of forming a bridge contact as recited in claim 14, wherein said refractory metal is evaporated onto the substrate from a plurality of offset evaporation sources.

Claim 20

Dependent Claim 33 words

The method of forming a bridge contact as recited in claim 15, wherein said titanium is evaporated onto the substrate while the substrate is heated to a temperature of at least 370° C.

Claim 21

Dependent Claim 27 words

The method of forming a bridge contact as recited in claim 15, wherein said substrate is sintered at 700° C. in a 95% nitrogen -5% hydrogen ambient.

Claim 22

Independent Claim 154 words

A method of forming a silicide bridge contact between two relatively coplanar silicon regions on a substrate that are separated by a thin insulating region having a small lateral length, without forming a bridge contact between other silicon regions on the substrate that are separated by other insulating regions having lateral lengths that are greater than the lateral length of the thin insulating layer, comprising the steps of: forming a layer of refractory metal under conditions such that the metal has a substantially columnar grain structure and a minimal amount of matrix material; sintering the substrate under conditions that limit the lateral formation of silicide, said refractory metal reacting with the substrate to form a silicide above said silicon regions and said thin insulating region without forming a silicide above said other insulating regions; and exposing the substrate to an etchant that preferentially removes remaining portions of said refractory metal without removing said silicide.

Claim 23

Independent Claim 154 words

A method of forming a silicide bridge contact between two relatively coplanar silicon regions on a substrate that are separated by a thin insulating region having a small lateral length, without forming a bridge contact between other silicon regions on the substrate that are separated by other insulating regions having lateral lengths that are greater than the lateral length of the thin insulating layer, comprising the steps of: forming a layer of refractory metal under conditions such that the metal has a substantially columnar grain structure and a minimal amount of matrix material; sintering the substrate under conditions that limit the lateral formation of silicide, said refractory metal reacting with the substrate to form a silicide above said silicon regions and said thin insulating region without forming a silicide above said other insulating regions; and exposing the substrate to an etchant that preferentially removes remaining portions of said refractory metal without removing said silicide.

Claim 24

Dependent Claim 27 words

The method of forming a bridge contact as recited in claim 20, wherein said grains have a lateral length that approximates that of said thin insulating region.

Claim 25

Dependent Claim 30 words

The method of forming a bridge contact as recited in claim 21, wherein said layer of refractory metal comprises titanium that is evaporated onto the substrate at approximately 370° C.

Claim 26

Independent Claim 178 words

A method of forming a silicide bridge contact between two relatively coplanar silicon regions on a substrate that are separated by a thin insulating region having a small lateral length, without forming a bridge contact between other silicon regions on the substrate that are separated by other insulating regions having lateral lengths that are appreciably greater than the lateral length of the thin insulating layer, comprising the steps of: forming a layer of titanium metal on the substrate, the substrate being heated to a temperature at which the titanium has a substantially columnar grain structure with a minimal amount of matrix material, said grains having a lateral length that approximates said lateral length of said thin insulating region; sintering the substrate at approximately 700° C. in a nitrogen atmosphere, said refractory metal reacting with the substrate to form a silicide above said silicon regions and said thin insulating region without forming a silicide above said other insulating regions; and exposing the substrate to an acid that preferentially removes remaining portions of said refractory metal without removing said silicide.

Claim 27

Independent Claim 178 words

A method of forming a silicide bridge contact between two relatively coplanar silicon regions on a substrate that are separated by a thin insulating region having a small lateral length, without forming a bridge contact between other silicon regions on the substrate that are separated by other insulating regions having lateral lengths that are appreciably greater than the lateral length of the thin insulating layer, comprising the steps of: forming a layer of titanium metal on the substrate, the substrate being heated to a temperature at which the titanium has a substantially columnar grain structure with a minimal amount of matrix material, said grains having a lateral length that approximates said lateral length of said thin insulating region; sintering the substrate at approximately 700° C. in a nitrogen atmosphere, said refractory metal reacting with the substrate to form a silicide above said silicon regions and said thin insulating region without forming a silicide above said other insulating regions; and exposing the substrate to an acid that preferentially removes remaining portions of said refractory metal without removing said silicide.

Claim 28

Dependent Claim 32 words

The method of forming a bridge contact as recited in claim 23, wherein said substrate is heated to a temperature of approximately 370° C. when said layer of titanium is formed thereon.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	1994-01-07	1994-07-09	1995-01-08	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	1998-01-07	1998-07-09	1999-01-08	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	2002-01-07	2002-07-09	2003-01-08	$7700.00	Window Closed / Lapsed

Silicide bridge contact process

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