# US 6,294,461 B1 · Structure for contact formation using a silicon-germanium alloy

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- Number: US 6,294,461 B1
- Document ID: US6294461B1
- Status: Granted
- Kind: B1
- Application number: 09/592,748
- Filed: 2000-06-13
- Granted: 2001-09-25
- Earliest claimed: 1998-02-27
- Assignees: Micron Technology, Inc.
- Inventors: Randhir P. S. Thakur
- Web page: https://patentgrep.com/patent/US6294461B1

## CPC

- H10W 20/076: {in via holes or trenches}
- H10D 64/0113: {the conductive layers comprising highly doped semiconductor materials, e.g. polysilicon layers or amorphous silicon layers}
- H10W 20/033: {in openings in dielectrics}
- H10W 20/047: {by introducing additional elements therein}
- H10W 20/0523: {by irradiating with ultraviolet or particle radiation}
- H10W 20/0526: {by thermal treatment thereof}
- H10W 20/057: {by selectively depositing, e.g. by using selective CVD or plating}
- H10W 20/081: {by forming openings in the dielectric parts}
- Y10S 257/915: with titanium nitride portion or region
- H10W: GENERIC PACKAGES, INTERCONNECTIONS, CONNECTORS OR OTHER CONSTRUCTIONAL DETAILS OF DEVICES COVERED BY CLASS H10
- H10D: INORGANIC ELECTRIC SEMICONDUCTOR DEVICES
- Y10S: TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS

## Abstract

A new method and structure for improved contact using doped silicon is provided. The structures are integrated to several higher level embodiments. The improved contact has low contact resistivity. Improved junctions are thus provided between an IGFET device and substuent metallization layers. The improvements are obtained through the use of a silicon-germanium (Si—Ge) alloy. The alloy can be formed from depositing germanium onto the substrate and subsequently annealing the contact or by selectively depositing the preformed alloy into a contact opening. The above advantages are incorporated with relatively few process steps.

## Claims

### Claim 1

A method for forming a semiconductor contact comprising:
forming a contact opening in a dielectric layer on a semiconductor substrate;
depositing a first contact material on the semiconductor substrate, and within the contact opening in the dielectric layer;
depositing a barrier metal on the first contact material;
annealing the contact;
depositing a second contact material on the barrier metal; and
depositing a third contact material on the second contact material.

### Claim 2 (depends on 1)

The method of claim 1 wherein annealing the contact comprises forming an alloy between the first contact material and the semiconductor substrate.

### Claim 3 (depends on 1)

The method of claim 1 wherein depositing the first contact material comprises depositing the first contact material prior to depositing the barrier metal.

### Claim 4 (depends on 1)

The method of claim 1 wherein depositing the first contact material comprises depositing germanium (Ge).

### Claim 5

A method for forming a semiconductor contact comprising:
forming a contact opening in a dielectric layer on a semiconductor substrate;
depositing a first contact material on the semiconductor substrate, and within the contact opening in the dielectric layer;
depositing a barrier metal on the first contact material comprising:
depositing a layer of titanium (Ti); and
depositing a layer of titanium nitride (TiN) on the layer of titanium (Ti)
annealing the contact;
depositing a second contact material on the barrier metal; and
depositing a third contract material on the second contract material.

### Claim 6 (depends on 5)

The method of claim 5 wherein depositing the barrier metal comprises depositing the layer of titanium (Ti) prior to depositing the first contact material.

### Claim 7 (depends on 1)

The method of claim 1 wherein depositing a second contact material comprises depositing a refractory metal.

### Claim 8

A method for forming a semiconductor contact comprising:
forming a contact opening in a dielectric layer on a semiconductor substrate;
depositing a first contact material on the semiconductor substrate, and within the contact opening in the dielectric layer;
depositing a barrier metal on the first contact material;
annealing the contact;
depositing a second contact material on the barrier metal; and
depositing a aluminum (Al) on the second contract material.

### Claim 9

A method for forming a semiconductor contact comprising:
forming a contact opening in a dielectric layer on a semiconductor substrate;
forming an alloy material on the semiconductor substrate and within the contact opening in the dielectric layer;
depositing a barrier metal on the alloy material;
depositing a first contact material on the barrier metal; and
depositing a second contact material on the first contact material.

### Claim 10 (depends on 9)

The method of claim 9 wherein forming the alloy material comprises forming an alloy including silicon and germanium.

### Claim 11 (depends on 9)

The method of claim 9 wherein forming the alloy material is achieved by epitaxial deposition.

### Claim 12 (depends on 9)

The method of claim 9 wherein forming the contact opening in the dielectric layer comprises forming a contact opening in borophosphorus silicate glass (BPSG).

### Claim 13

A method for forming a semiconductor contact comprising:
forming a contact opening in a dielectric layer on a semiconductor substrate;
forming an oxide layer on the semiconductor substrate and within the contact opening in the dielectric layer;
removing a portion of the oxide layer that is over the semiconductor substrate; and
forming an alloy material on the semiconductor substrate and adjoining a remaining portion of the oxide layer.

### Claim 14 (depends on 13)

The method of claim 13 wherein forming the oxide layer comprises forming a layer of tetraethyl orthosilicate (TEOS).

### Claim 15

A method for forming a semiconductor contact comprising:
forming a contact opening in a dielectric layer on a semiconductor substrate;
forming an oxide layer on the semiconductor substrate and within the contact opening in the dielectric layer;
removing a portion of the oxide layer that is over the semiconductor substrate; and
forming an alloy material on the semiconductor substrate and adjoining a remaining portion of the oxide layer, the alloy material comprising silicon and geranium.

### Claim 16 (depends on 13)

The method of claim 13 wherein forming the alloy material is achieved by epitaxial deposition.

### Claim 17 (depends on 13)

The method of claim 13 wherein forming the contact opening within the dielectric layer comprises forming a contact opening in borophosphorus silicate glass (BPSG).

### Claim 18

A method for forming a semiconductor contact comprising:
forming a contact opening in a dielectric layer on a semiconductor substrate;
forming an oxide layer on the semiconductor substrate and within the contact opening in the dielectric layer;
removing a portion of the oxide layer that is over the semiconductor substrate;
implanting a germanium (Ge) contact in the semiconductor substrate; and
annealing the contact.

### Claim 19 (depends on 18)

The method of claim 18 wherein forming the oxide layer comprises tetraethyl orthosilicate (TEOS).

### Claim 20 (depends on 18)

The method of claim 18 wherein depositing the germanium (Ge) contact comprises forming an alloy between the germanium (Ge) contact and the silicon substrate.

### Claim 21 (depends on 18)

The method of claim 18 wherein forming the contact opening within the dielectric layer comprises forming a contact opening in borophosphorus silicate glass (BPSG).