Two-stage roughing and controlled deposition rates for fabricating laser ablation masks

• US 6,537,707 B1
• Filed: 03/15/2000
• Issued: 03/25/2003
• Est. Priority Date: 03/15/2000
• Status: Expired due to Fees

• Current Assignee: Agilent Technologies Europe BV (Agilent Technologies, Inc.)
• Original Assignee: Agilent Technologies, Inc.
• Inventors: Lee, Lawrence Hakchu
• Primary Examiner(s): Huff, Mark F.
• Assistant Examiner(s): Mohamedulla, Saleha R.
• Application Number:
  US09/525,981
• Time in Patent Office: 1,105 Days
• Field of Search: 430/5, 430/322, 430/323, 430/324, 219/121.7, 216/27, 427/569, 427/576, 427/579, 427/585
• US Class Current: 430/5
• CPC Class Codes: C23C 14/54 Controlling or regulating the coating process
• CPC Class Codes: C23C 14/564 Means for minimising impurities in the coating chamber such as dust, moisture, residual gases

Abstract

A method of fabricating a high energy radiation mask, such as a laser ablation mask for manufacturing inkjet printheads, includes a multi-stage evacuation process and/or a step of reducing the deposition rate of silicon dioxide during formation of a dielectric stack. When the multi-stage evacuation procedure is combined with the slower deposition rate of silicon dioxide, the resulting mask has a surprisingly low defect density. In the first embodiment, the evacuation procedure is initiated using a low-rate first evacuation connection. The relatively slow purging of a vacuum chamber in which the dielectric stack is subsequently formed controls turbulence and environmental changes that can generate contamination and water along the surface of the substrate on which the dielectric stack is formed. When a pressure setpoint is reached, a second roughing connection is activated to increase the speed of the procedure. The second connection has a higher maximum rate than the first connection. In the preferred embodiment, there is an overlap in the activations of the first and second connections. When another setpoint is reached, a high vacuum connection is activated in order to bring the vacuum chamber to a high vacuum condition for deposition of the dielectric stack. The dielectric stack includes alternating layers of higher refractive index material and low refractive index material. The low refractive index material is silicon dioxide that is deposited at a rate in the optimal range of 1.0 Å/second to 3.0 Å/second. Practical considerations dictate a range of 1.6 Å/second to 2.4 Å/second.

Claims

1. A method of fabricating a high energy radiation mask comprising steps of:

locating a substrate in a vacuum chamber;

activating a first roughing evacuation connection to said vacuum chamber, said first roughing evacuation connection having a first maximum rate of evacuation;

detecting when pressure within said vacuum chamber is reduced to a first threshold pressure;

activating a second roughing evacuation connection to said vacuum chamber in response to detecting that said pressure is below said first threshold pressure, said second roughing connection having a second maximum rate that is greater than said first maximum rate;

detecting when pressure within said vacuum chamber is reduced to an intermediate threshold pressure that is between said first threshold pressure and a second threshold pressure;

deactivating said first roughing evacuation connection in response to detecting that said pressure within said vacuum chamber is below said intermediate threshold pressure, thereby providing a range between said first and intermediate threshold pressures in which said first and second roughing evacuation connections are simultaneously activated;

detecting when pressure within said vacuum chamber is reduced to said second threshold pressure;

activating a high vacuum pump connection to said vacuum chamber in response to detecting that said pressure is below said second threshold pressure; and

depositing at least one layer on said substrate within said vacuum chamber to form a coating that is resistant to damage when exposed to a high energy beam.

2. The method of claim 1 wherein said steps of activating said first and second roughing evacuation connections include selectively operating two independent vacuum pumps.

3. The method of claim 2 wherein said step of activating said high vacuum pump includes selectively operating a diffusion pump that is independent of said vacuum pumps operated in steps of activating said first and second roughing evacuation connections.

4. The method of claim 1 further comprising the step of:

deactivating said second roughing evacuation connection in response to detecting that said pressure within said vacuum chamber is below said second threshold pressure.

5. The method of claim 1 wherein said depositing step includes vapor depositing a stack of layers for forming a laser ablation mask, including depositing a plurality of silicon oxide layers at a rate in the range of 1 Å

/second to 3 Å

/second.

6. The method of claim 5, wherein said step of vapor depositing includes alternating said silicon oxide layers with layers of hafnium oxide.

7. The method of claim 5 further comprising a step of patterning said layer stack to form a selected exposure pattern.

8. The method of claim 7 wherein said step of patterning is implemented to form a laser ablation mask for fabricating an inkjet printhead.

9. A method of fabricating a laser ablation mask comprising steps of:

locating a substrate in a vacuum chamber;

activating a two-stage roughing procedure for evacuating said vacuum chamber to a threshold pressure level, including;

(a) triggering a first stage roughing connection;

(b) triggering a second stage roughing connection when pressure within said vacuum chamber reaches a first threshold pressure level, including maintaining said first stage roughing connection;

(c) terminating said first stage roughing connection when said pressure within said vacuum chamber reaches an intermediate threshold pressure level less than said first threshold pressure level, including maintaining said second stage roughing connection;

activating a high evacuation vacuum procedure for evacuating said vacuum chamber to a high vacuum pressure level, said high evacuation vacuum procedure being activated when said pressure in said vacuum chamber reaches a second threshold pressure level below said first and intermediate threshold pressure levels; and

depositing material on said substrate in said vacuum chamber to form a layer stack that is resistant to damage by exposure to a high energy laser source, including depositing a plurality of spaced apart silicon dioxide layers at a rate in the range of 1 Å

/second to 3 Å

/second.

10. The method of claim 9 further comprising a step of patterning said layer stack to form an exposure pattern for manufacturing inkjet printheads.

11. The method of claim 9 wherein said step of depositing material includes depositing hafnium layers between said silicon dioxide layers.

12. The method of claim 9 wherein said two-stage roughing procedure is implemented using two vacuum sources.