Integrated sputtering target assembly

• US 5,565,071 A
• Filed: 05/24/1995
• Issued: 10/15/1996
• Est. Priority Date: 11/24/1993
• Status: Expired due to Term

• Current Assignee: Applied Materials Incorporated
• Original Assignee: Applied Materials Incorporated
• Inventors: Demaray, Richard E., Berkstresser, David E., Herrera, Manuel J.
• Primary Examiner(s): Weisstuch, Aaron
• Application Number:
  US08/449,618
• Time in Patent Office: 510 Days
• Field of Search: 204/192.12, 204/298.07, 204/298.09, 204/298.12, 204/298.2, 204/192.13, 204/298.03
• US Class Current: 204/192.12
• CPC Class Codes: C23C 14/3407 Cathode assembly for sputtering apparatus, e.g. Target
• CPC Class Codes: C23C 14/564 Means for minimising impurities in the coating chamber such as dust, moisture, residual gases
• CPC Class Codes: F28F 3/12 Elements constructed in the shape of a hollow panel, e.g. with channels F28D1/02, F28D1/03 take precedence
• CPC Class Codes: H01J 2237/022 Avoiding or removing foreign or contaminating particles, debris or deposits on sample or tube
• CPC Class Codes: H01J 37/32458 Vessel
• CPC Class Codes: H01J 37/3411 Constructional aspects of the reactor
• CPC Class Codes: H01J 37/3435 Target holders (includes backing plates and endblocks)
• CPC Class Codes: H01J 37/3497 Temperature of target

Abstract

A target plate assembly completely covers and seals against a top opening of a sputtering processing chamber. Cooling liquid connections are provided only from the perimeter of the target assembly. When a top vacuum chamber seals the side opposite the pressure chamber, the pressure on both sides of the target assembly is nearly equalized. Large thin target assemblies, such as large flat plates used for flat panel displays can be sputtered effectively and uniformly without adverse sputtering effects due to target deflection or cooling deficiencies.

A target, target backing plate, and cover plate form the target plate assembly. The sputtering target assembly includes an integral cooling passage. A series of grooves are constructed in either the target backing plate or the target backing cooling cover plate, which are then securely bonded to one another. The sputtering target can be a single monolith with a target backing plate or can be securely attached to the target backing plate by one of any number of conventional bonding methods. Tantalum to titanium, titanium to titanium and aluminum to titanium, diffusion bonding can be used.

The energized target assembly is protected from adjacent components by overlapping insulators to prevent accidents and isolate the target assembly from other components. An electrical connection to the target assembly remains unconnected until a vacuum is produced in the top chamber.

Claims

1. A sputtering assembly comprising:

a sputtering target in intimate contact with a first side of a target backing plate assembly;

said target backing plate assembly having a first side configured to cover an opening of a sputtering chamber so as to seal the opening;

a top chamber having a bottom opening sealed against a second side of said target backing plate assembly opposite from said first side such that said target backing plate assembly acts as a wall between said sputtering chamber and said top chamber;

wherein said target backing plate assembly is disposed between said bottom opening of said top chamber and said opening of said sputtering chamber so that a pressure load on said target plate assembly due to differential pressure between the chambers is reduced as the pressure in said top chamber and the pressure in said sputtering chamber approach one another,

a top chamber pressure control system to control the pressure in said top chamber to be different from the pressure in said sputtering chamber,

wherein a portion of said target backing plate assembly and sputtering target are configured to bow as the differential pressure between the top chamber and the sputtering chamber changes,

wherein the pressure in at least one of the two chambers is adjustable to control the bow in a portion of the target assembly and a portion of the sputtering target to change the distance between said portion of said sputtering target and a portion of said object being sputter deposited so as to improve the uniformity of film thickness sputter deposited on the object being sputter deposited.

2. The sputtering assembly as in claim 1, wherein a connection from a vacuum source to said top chamber is routed through a rough vacuum port adjacent to said sputtering chamber and around said target backing plate assembly to said top chamber, such that positioning of the target backing plate assembly and the top chamber to be sealed for evacuation simultaneously provides a seal between said top chamber and said connection from said vacuum source.

3. A sputtering assembly as in claim 1, wherein said backing plate assembly has heat exchange fluid passages therethrough, said heat exchange fluid passages having one or more inlet and outlet openings.

4. The sputtering assembly as in claim 3, wherein said target backing plate assembly is configured without a seal between a passage or chamber at vacuum pressure and said cooling fluid passages.

5. The sputtering assembly as in claim 3, further comprising a non-contact measuring instrument to measure the displacement due to bowing of said portion of the target backing plate assembly from a reference location.

6. The sputtering assembly as in claim 5, wherein the instrument for measurement of the displacement due to bowing provides a feedback signal to said top chamber pressure control system so that pressure in said top chamber is adjusted to maintain approximately a desired distance between the object to be sputtered and a surface of said portion of said sputtering target whose location can be adjusted by changing the bowing of the target backing plate assembly and the sputtering target by changing the differential pressure between the top chamber and the sputtering chamber.

7. The sputtering assembly as in claim 1, further comprising a non-contact measuring instrument to measure the displacement due to bowing of said portion of the target backing plate assembly from a reference location.

8. The sputtering assembly as in claim 7, wherein the instrument for measurement of the displacement due to bowing provides a data signal to said top chamber pressure control system so that pressure in said top chamber is adjusted to maintain approximately a desired distance between the object to be sputtered and a surface of said portion of said sputtering target which can be bowed.

9. A sputtering process comprising the steps of:

placing a target assembly on a top surface of a processing chamber such that when a vacuum is provided to said processing chamber said processing chamber is sealed by said target assembly;

evacuating said processing chamber to provide a processing chamber vacuum pressure in said chamber sealed by said target assembly;

placing a cover chamber on said target assembly on a back side of said target assembly opposite a target side of said assembly, said cover chamber being supported on said back side of said target assembly such that a vacuum seal is created against said back side of said target assembly, thereby enclosing at least the portion of said back side of said target assembly corresponding to the location on said target side of said target assembly which comprises a sputtering target; and

evacuating said cover chamber to provide a cover chamber vacuum pressure in said cover chamber;

setting and adjusting the differential pressure between said cover chamber and said processing chamber during sputtering to control the bowing of a portion of the target assembly located between the processing chamber and the cover chamber to adjust the distance between a portion of the sputtering target susceptible to movement due to bowing of the target assembly between adjacent chambers and an object to be sputtered to improve the uniformity of sputtering film sputter deposited on said object in said sputter chamber during sputtering of said sputtering target on said target side of said target assembly as a portion of said sputtering target susceptible to movement due to bowing is eroded away during sputtering.

10. The sputtering process as in claim 9, wherein the step of adjusting includes:

adjusting the differential pressure between said cover chamber and said processing chamber according to a measurement of the bowing of said portion of said target assembly between said processing chamber and said cover chamber.

11. The sputtering process as in claim 10, wherein the measurement is done by a non-contact measuring method.