Method for mounting a flip chip on a substrate

• US 20070145102A1
• Filed: 12/22/2006
• Published: 06/28/2007
• Est. Priority Date: 12/22/2005
• Status: Active Grant

• Current Assignee: Oerlikon Assembly Equipment AG
• Original Assignee: Unaxis International Trading Ltd.
• Inventors: Grueter, Ruedi, Blessing, Patrick, Werne, Dominik
• Granted Patent: US 7,597,234 B2
• Time in Patent Office: Days
• US Class Current: 228/101
• CPC Class Codes: H01L 21/67144 Apparatus for mounting on conductive members, e.g. leadframes or conductors on insulating substrates
• CPC Class Codes: H01L 21/681 using optical controlling means
• CPC Class Codes: H01L 2224/75 Apparatus for connecting with bump connectors or layer connectors
• CPC Class Codes: H01L 2224/757 Means for aligning
• CPC Class Codes: H01L 2224/75702 in the upper part of the bonding apparatus, e.g. in the bonding head
• CPC Class Codes: H01L 2224/758 Means for moving parts
• CPC Class Codes: H05K 13/0812 the monitoring devices being integrated in the mounting machine, e.g. for monitoring components, leads, component placement
• CPC Class Codes: H05K 2201/10674 Flip chip

Abstract

The invention concerns a method for mounting a semiconductor chip with bumps on one surface onto a substrate location of a substrate, whereby the bumps are brought into contact with corresponding pads on the substrate location. Reference marks are attached to the bondhead that enable measurement of the actual position of the semiconductor chip as well as measurement of the actual position of the substrate location in relation to a system of coordinates defined by the reference marks. Positional displacement of the individual components of the assembly machine caused by thermal influences can be compensated without perpetual calibration procedures having to be carried out.

Claims

1. A method for mounting a semiconductor chip having a surface with bumps onto a substrate location of a substrate whereby the bumps are brought into contact with corresponding pads on the substrate location whereby the positioning of the semiconductor chip over the substrate location is done by means of three axes of motion, the method comprising:

picking the semiconductor chip from a wafer table;

turning the semiconductor chip by 180°

about an axis parallel to the surface with the bumps;

passing the semiconductor chip over to a bondhead;

presenting the substrate location;

the method further comprising the steps

A) with a first camera, making an image of the semiconductor chip whereby the image contains the bumps of the semiconductor chip as well as reference marks attached to the bondhead, whereby the three axes of motion are in first positions, and determining the position and orientation of the actual position of the semiconductor chip in relation to a system of coordinates defined by the reference marks and calculating a first correction vector v₁ that describes the deviation of the actual position of the semiconductor chip from its set position,

B) with a second camera, making a first image whereby the substrate location is visible in the image, determining the position and orientation of the substrate location in relation to the system of coordinates defined by the reference marks, whereby fictitious positions are used for the positions of the reference marks that they would take up if the three axes of motion had been moved from the first positions by a vector v to second positions, and calculating a second correction vector v₂ that describes the deviation of the actual position of the substrate location from its set position,

C) calculating the positions to be approached by the three axes of motion under consideration of the vector v and the two correction vectors v₁ and v₂,

D) moving the three axes of motion to these calculated positions, and

E) depositing the semiconductor chip onto the substrate location.

2. A method according to claim 1, characterised in that after step D the following steps are carried out:

with the second camera, making a second image whereby the reference marks attached to the bondhead are visible in the second image, and determining the actual positions of the reference marks,

calculating a third correction vector v₃ that describes the deviation of the actual positions of the reference marks from the used fictitious positions of the reference marks assumed in step B on evaluation of the first image made by the second camera,

adapting the vector v to v=v+v₃,

if at least one component of the third correction vector v₃ is greater than a specified limit value, moving at least the axis of motion corresponding to this component to a new, corrected position.