Method of fabricating a micro-electromechanical actuating mechanism

• US 7,331,101 B2
• Filed: 07/08/2005
• Issued: 02/19/2008
• Est. Priority Date: 10/16/1998
• Status: Expired due to Fees

• Current Assignee: Memjet Technology Ltd. (Memjet Limited)
• Original Assignee: Silverbrook Research Pty Limited
• Inventors: Silverbrook, Kia
• Primary Examiner(s): TUGBANG, ANTHONY D
• Application Number:
  US11/176,158
• Publication Number:
  US 20050270335A1
• Time in Patent Office: 956 Days
• Field of Search: 296/11, 298/901, 298/46, 298/31, 438/21, 438/199, 438/210, 438/330, 438/382, 347 68- 72, 347/20, 347/27, 347/40, 347/50, 347/54, 347/63, 347/65
• US Class Current: 29/611
• CPC Class Codes: B41J 2/04505 aiming at correcting alignment
• CPC Class Codes: B41J 2/04516 preventing formation of satellite drops
• CPC Class Codes: B41J 2/04518 reducing costs
• CPC Class Codes: B41J 2/0452 reducing demand in current or voltage
• CPC Class Codes: B41J 2/04528 aiming at warming up the head
• CPC Class Codes: B41J 2/04541 Specific driving circuit
• CPC Class Codes: B41J 2/04543 Block driving
• CPC Class Codes: B41J 2/04553 detecting ambient temperature
• CPC Class Codes: B41J 2/04563 detecting head temperature; Ink temperature
• CPC Class Codes: B41J 2/04565 detecting heater resistance
• CPC Class Codes: B41J 2/0457 Power supply level being detected or varied
• CPC Class Codes: B41J 2/04571 detecting viscosity
• CPC Class Codes: B41J 2/04585 controlling heads based on thermal bent actuators
• CPC Class Codes: B41J 2/04588 using a specific waveform
• CPC Class Codes: B41J 2/0459 Height of the driving signal being adjusted
• CPC Class Codes: B41J 2/04591 Width of the driving signal being adjusted
• CPC Class Codes: B41J 2/04593 Dot-size modulation by changing the size of the drop
• CPC Class Codes: B41J 2/04596 Non-ejecting pulses
• CPC Class Codes: B41J 2/04598 Pre-pulse
• CPC Class Codes: B41J 2/14427 Structure of ink jet print heads with thermal bend detached actuators
• CPC Class Codes: B41J 2/1623 : bonding and adhesion
• CPC Class Codes: B41J 2/1626 : etching
• CPC Class Codes: B41J 2/1628 : dry etching
• CPC Class Codes: B41J 2/1629 : wet etching
• CPC Class Codes: B41J 2/1631 : photolithography
• CPC Class Codes: B41J 2/1632 : machining
• CPC Class Codes: B41J 2/1635 : dividing the wafer into individual chips
• CPC Class Codes: B41J 2/1637 : molding
• CPC Class Codes: B41J 2/1639 : sacrificial molding
• CPC Class Codes: B41J 2/164 : thin film formation
• CPC Class Codes: B41J 2/1642 : thin film formation by CVD [chemical vapor deposition]
• CPC Class Codes: B41J 2/1646 : thin film formation by sputtering
• CPC Class Codes: B41J 2/1648 : Production of print heads with thermal bend detached actuators
• CPC Class Codes: B41J 2002/14491 : Electrical connection
• CPC Class Codes: B41J 25/005 : for serial printing movements superimposed to character- or line-spacing movements
• CPC Class Codes: Y10T 29/49083 : Heater type
• CPC Class Codes: Y10T 29/49155 : Manufacturing circuit on or in base
• CPC Class Codes: Y10T 29/49401 : Fluid pattern dispersing device making, e.g., ink jet

Abstract

A method of fabricating a micro-electromechanical actuating mechanism on a wafer substrate includes the step of carrying out a CMOS fabrication process on the wafer to form transistor control and drive circuitry. Sacrificial material is deposited on the transistor control and drive circuitry. The sacrificial material is etched to provide connection access to the drive circuitry. A MEMS fabrication process is carried out on the layer of sacrificial material to form a micro-electromechanical actuator connected to the drive circuitry and responsive to electrical signals from the drive circuitry. The sacrificial material is removed to free the actuator. The steps of carrying out the CMOS and MEMS fabrication processes are such that the transistor circuitry is interposed between the actuator and the wafer substrate.

Claims

1. A method of fabricating a micro-electromechanical actuating mechanism on a wafer substrate, the method comprising the steps of:

carrying out a CMOS fabrication process on the wafer to form transistor control and drive circuitry;

depositing sacrificial material on the transistor control and drive circuitry;

etching the sacrificial material to provide connection access to the drive circuitry;

carrying out a MEMS fabrication process on the layer of sacrificial material to form a micro-electromechanical actuator connected to the drive circuitry and responsive to electrical signals from the drive circuitry; and

removing the sacrificial material to free the micro-electromechanical actuator, wherein

the steps of carrying out the CMOS and MEMS fabrication processes are such that the transistor circuitry is interposed between the actuator and the wafer substrate.

2. A method as claimed in claim 1, in which the step of carrying out the MEMS fabrication process is such that the micro-electromechanical actuator is elongate, with one end anchored to the substrate.

3. A method as claimed in claim 2, in which the step of carrying out the CMOS fabrication process includes the step of forming traces for the transistor circuitry such that the traces include a series of portions that extend transversely with respect to the micro-electromechanical actuator.

4. A method as claimed in claim 3, in which the step of carrying out the MEMS fabrication process includes the step of forming actuator layers on the sacrificial material such that one of the actuator layers defines a series of corrugations that correspond with the series of transversely extending portions of the heater layer.

5. A method as claimed in claim 4, in which the step of forming the actuator layers includes the step of forming said one of the actuator layers in the form of a resistive heating circuit of a conductive material in electrical contact with the drive transistor circuitry to be heated on receipt of an electrical signal from the drive transistor circuitry.

6. A method as claimed in claim 5, in which the resistive heating circuit is formed with a conductive material having a coefficient of thermal expansion sufficient to result in expansion and subsequent contraction of the heating circuit upon heating and subsequent cooling to result in displacement of the micro-electromechanical actuator with respect to the substrate.

7. A method as claimed in claim 6, in which the step of forming said resistive heating circuit incorporates the steps of forming a fluid ejection paddle such that said one of the actuator layers also defines the fluid ejection paddle, and forming an electrical discontinuity between the fluid ejection paddle and the heating circuit to insulate the fluid ejection paddle.

8. A method as claimed in claim 7, which includes the step of forming a nozzle chamber structure on the substrate to define a nozzle chamber such that the fluid ejection paddle extends into the nozzle chamber and the actuator extends through a wall of the nozzle chamber structure.