Method of releasing devices from a substrate

• US 20040173575A1
• Filed: 03/05/2003
• Published: 09/09/2004
• Est. Priority Date: 03/05/2003
• Status: Active Grant

• Current Assignee: Applied Materials Incorporated
• Original Assignee: Applied Materials Incorporated
• Inventors: Khan, Anisul H., Kumar, Ajay, Pamarthy, Sharma V., Thekdi, Sanjay M.
• Granted Patent: US 6,905,616 B2
• Time in Patent Office: Days
• US Class Current: 216/86
• CPC Class Codes: B81C 1/00952 Treatments or methods for avoiding stiction during the manufacturing process not provided for in groups B81C1/00928 - B81C1/00944

Abstract

Micro devices are formed in situ in a high density in a substrate comprising a masked silicon layer over a stop layer of a silicon compound, by anisotropically etching the desired feature in the silicon layer, overetching to form a notch at the silicon-stop layer interface, depositing a protective fluorocarbon polymer layer on the sidewalls and bottom of the etched silicon layer, and isotropically etching to separate the etched feature from the stop layer. This method avoids the problems of stiction common in other methods of forming micro devices.

Claims

1. A method of releasing devices formed in a silicon layer over a stop layer without stiction comprising,

a) anisotropically etching features in a masked silicon layer down to the stop layer;

b) overetching the features to form a notch at the silicon-stop layer interface;

c) depositing a fluorine-containing polymer over the sidewalls and bottom of the etched features; and

d) isotropically etching to widen the notch until the etched feature becomes separated from the stop layer.

2. A method according to claim 1 wherein steps a) through d) are carried out sequentially in situ in a plasma etch chamber.

3. A method according to claim 1 wherein step a) is carried out using SF₆ and a passivation gas at a chamber pressure of about 18 miillitorr and about 700 watts of source power.

4. A method according to claim 1 wherein step b) is carried out using a mixture of SF₆ and a fluorocarbon gas at a chamber pressure of about 25 millitorr until a notch forms at the silicon-stop layer interface.

5. A method according to claim 1 wherein step c) is carried out using a fluorine-containing gas having the formula C_xF_yH_z wherein x is an inter of 1 to 5;

y is an integer of 1 to 12, and z is an integer of 0 to 12.

6. A method according to claim 1 wherein step d) is carried out using an etchant selected from the group consisting of SF₆ and XnF₂ until the silicon feature is separated from the stop layer.

7. A method according to claim 1 wherein steps a) through d) are carried out in sequence.

8. A method according to claim 1 wherein steps a) to c) are carried out sequentially, the photoresist mask layer is removed, another photoresist layer deposited and patterned, steps a) to c) repeated one or more times to form a more complex pattern in the silicon layer, and carrying out step d).