Method for inspecting a semiconductor device

A method for inspecting a semiconductor device includes an inspection station (10), a handling system (12), a microscope (14), a camera (18), and a computer (20) having a monitor (22). A magnified image (40) of the device being inspected is transmitted to monitor (22) via camera (18). A template image (60) is then recalled from computer readable memory and is superimposed upon the magnified image of the device appearing on monitor (22). The template image (60) includes transparent regions (62) and opaque regions (64). The opaque regions block out all areas of the device not associated with the characteristic being inspected, while the transparent regions highlight the area of interest. Using the superimposed image (70), the operator can quickly focus on the area of the device requiring attention. In specific embodiments of the invention, a template is used to assist inspection of a wire bond configuration, a die attach material bondline, lead skew, and mark placement.

FIELD OF THE INVENTION 
The present invention relates to inspection methods, and more particularly 
to methods for inspecting semiconductor devices. 
BACKGROUND OF THE INVENTION 
Inspection operations are imposed throughout manufacturing processes to 
insure that the product being produced conforms to the manufacturer's 
quality standards. Semiconductor manufacturing is no exception. Inspection 
for defects, for alignment tolerances, and for critical dimension control 
are just a few of the characteristics of a semiconductor device which are 
inspected during wafer fabrication processes. Once wafer fabrication is 
complete, the wafer moves to assembly operations for packaging. Within 
assembly, inspections occur to insure, for example, that a semiconductor 
die is aligned properly within a package, that the appropriate number of 
wire bonds or solder bumps are formed on a device, and that the package 
leads are coplanar. 
During each of these inspection processes, an operator is charged with 
comparing the device being inspected to a standard which has been approved 
as an acceptable level of quality. The accepted standard can take many 
forms, but is very often simply a piece of paper noting in words or with a 
drawing what an acceptable product should look like. While such "paper 
standards" have the advantage of simplicity, use of paper standards also 
impose a high degree of human error. 
One example of a paper standard which is sometimes used by semiconductor 
manufacturers is the use of a paper wire bond diagram to inspect the 
configuration of wire bonds of a semiconductor device. Some semiconductor 
devices are designed such that not all bond pads of a die are wire bonded 
to a corresponding lead, or more commonly that not all lead of a designed 
package are wire bonded to a die bond pad. In order for an operator to 
understand which bond pads and which lead are to include wire bonds, a 
diagram is created on paper to indicate where wire bonds should be 
located. To inspect an actual wire bonded device, an inspector views the 
device through a microscope and compares the image as magnified by the 
microscope optics to the paper wire bond diagram. Having to repeatedly 
view the image of the device under the microscope and turn away to view 
the paper wire bond diagram creates a number of opportunities for error. 
For instance, operators can lose their place in making a comparison, 
creating the potential for portions of the device to pass without 
inspection. Furthermore, the repeated motion of viewing a microscope image 
and then viewing a paper image increases cycle time and reduces throughput 
during the inspection process. Also, because the paper wire bond diagram 
only marginally presents the actual image as seen under the microscope, 
use of a paper diagram tends to make the inspection process tedious, time 
consuming, confusing, and susceptible to error. 
With the emergence of highly advanced manufacturing and inspection 
equipment, some inspection operations have the potential for being fully 
automated. By incorporating optical recognition capability and integrated 
software, some semiconductor manufacturing and inspection equipment is 
available which does an electronic comparison between the device being 
inspected and a stored electronic file containing information about a 
manufacturer's acceptable standards. For example, a digitized version of 
the device being inspected is generated and is compared to a digitized 
version of an accepted standard. The comparison of the two digitized files 
is performed by a computer, and the results of the comparison provide an 
"accepted" or "rejected" output. In an ideal world, such a sophisticated 
digital comparison would seem to be the perfect solution. However, in a 
manufacturing world, such a solution is sometimes not possible. The 
sophisticated equipment necessary to perform such automated inspections is 
very expensive. Moreover, the time it takes for the equipment to do the 
comparison and to provide a result only inhibits a manufacturer's goal of 
reducing total cycle time. Furthermore, the systems are not usually 
entirely automatic. Some human intervention is still needed, for example 
to make close judgement calls. 
Therefore, a need exists for an improved inspection process for 
semiconductor devices wherein an inspection can be accomplished in a very 
quick, efficient manner, with much smaller room for error as compared to 
prior art paper standard techniques. Moreover, it is desirable for such an 
inspection method to be practiced with minimal capital investment.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT 
The present invention provides a fast, inexpensive method of inspecting 
semiconductor devices at various stages throughout the manufacturing 
process, and particularly throughout the assembly process. While the 
present invention does not remove all possibility of error during the 
inspection process, the possibility of human error is significantly 
reduced as compared to prior art inspection methods which rely upon 
standards set upon paper. The present invention provides a nice compromise 
between the error prone inspection methods which rely upon operator 
judgment and those which are fully automated as a result of technological 
improvements in the inspection equipment, but which are expensive and 
require too much time to complete an inspection. Generally, a method of 
inspecting in accordance with the present invention involves positioning 
the device to be inspected under a microscope, and transmitting a 
magnified image of the device from the microscope to a computer monitor 
via a camera. A template which has been specifically created for the 
device characteristic which is being inspected is retrieved from computer 
memory or computer readable, memory and is displayed on the computer 
monitor, superimposed on the magnified device image already present on the 
monitor. An inspection station operator then compares the device being 
inspected as shown on the monitor with the template and determines whether 
the device falls within the accepted standards set by the manufacturer and 
as accounted for in the template. If the device being inspected conforms 
with the template, the device is accepted, otherwise the device is 
rejected. 
In more specific embodiments of the present invention, the characteristic 
being inspected is either a wire bond configuration, the location of a die 
attach material bondline, or lead and marking positions. In using the 
present invention to inspect a wire bond configuration, a template is 
created to have opaque portions and transparent portions. Opaque portions 
of the template are designed to block out all portions of the device being 
inspected except for the actual wire bonds. The transparent portions thus 
correspond to where actual wire bonds are supposed to be located. Upon 
superimposing the template on to the magnified image of the device being 
inspected, only the wire bonds will be visible on the computer monitor. 
Thus, the image which an inspection station operator looks at during an 
inspection is focused only where the operator needs to look to properly 
inspect the device. Extraneous portions of the magnified image are blocked 
out by the opaque regions of the template. Similarly, in using the present 
invention to inspect a die attach material bondline, a template is created 
to have opaque portions which block out portions of the magnified image 
other than the die attach bondline. Moreover, the template is designed to 
define a lower limit or an upper limit (or both) as to where the die 
attach material bondline can acceptably exist along the die side. 
Likewise, a template can be used to inspect external leads position in a 
packaged device. In the template, transparent portions highlight the leads 
tips and define acceptable limits on lead tip positions. A manufacturer's 
product marking position can also be inspected using templates. By 
employing a simple template with opaque and transparent regions 
superimposed upon a magnified image of the device being inspected, the 
present invention focuses an inspector's attention to that characteristic 
being inspected and facilitates a quick "pass" or "reject" ("go" or "no 
go") result for the inspection process. 
These and other features, and advantages, will be more clearly understood 
from the following detailed description taken in conjunction with the 
accompanying drawings. It is important to point out that the illustrations 
are not necessarily drawn to scale and that there can be other embodiments 
of the present invention which are not specifically illustrated. 
Throughout this description and in the figures, like reference numerals 
are sometimes used to designate identical or corresponding parts. 
FIG. 1 illustrates an inspection station 10 which is suitable for 
practicing the present invention. Inspection station 10 includes a 
handling system 12, a microscope 14, a camera 18, and a computer 20. 
Computer 20 includes a monitor 22, a keyboard 24, and a controller unit 26 
with memory. FIG. 2 is a process flow chart indicating the most important 
steps for carrying out an inspection process using the present invention. 
In operation, a semiconductor device or multiple devices are loaded into 
handling system 12, for example by inserting a cassette or magazine filled 
with a plurality of devices at the front end or entrance of the handling 
system. Handling system 12 is used to unload one device from the magazine 
and convey or index it to within a stage area in a field of view of 
microscope 14, as indicated by a step 30 in FIG. 2. In a conventional 
inspection process, an operator would view the device being inspected 
through the optics of the microscope. In accordance with the present 
invention, instead a magnified image 40 of the device being inspected is 
transmitted to monitor 22 by camera 18. Displaying the magnified image on 
monitor 22 is a step 32 of the: process flow of FIG. 2. As illustrated and 
described in reference to FIGS. 1-5, the characteristic being inspected is 
a wire bond configuration of a semiconductor device. Accordingly, the 
magnified image appearing on monitor 22 is that of a semiconductor die as 
it is wire bonded to a plurality of leads. 
Magnified image 40 as it appears on monitor 22 is illustrated in more 
detail in FIG. 3. Elements of the magnified image include a semiconductor 
die 42 (for example, an integrated circuit) which is mounted to a die 
paddle or die flag 44 of a lead frame. Also included as part of the lead 
frame are tie bars 46 which support the die flag, and a plurality of leads 
48. Semiconductor die 42 includes a plurality of bond pads 50 which are 
electrically coupled to the plurality of leads by a plurality of wire 
bonds 52. Wire bonds 52 are wire bonded between bond pads 50 and leads 48 
in accordance with conventional methods. During a wire bond configuration 
inspection, it is necessary to determine whether wire bonds 52 are wire 
bonded to the appropriate leads and the appropriate bond pads. In many 
instances, not all leads or not all bond pads of the die are designed to 
be used. Accordingly, during the inspection an operator will see that some 
leads do not have wire bonds connected to them. However, this may be by 
design. For an operator to determine which leads need to be bonded, and to 
which bond pads, in the past the operator referred to a paper wire bonding 
diagram. But in comparing the device being inspected to a wire bond 
diagram, there was large room for human operator error and confusion. The 
present invention simplifies the inspection process by eliminating the 
need for paper wire bonding diagrams, or other paper standards, and 
instead employs a template. 
In displaying the magnified image onto the monitor, it is preferred that 
the entire area to be inspected is within the field of view of the 
micrope, and is thus displayed on the monitor, as illustrated in FIG. 3. 
Once magnified image 40 is displayed on monitor 22, the inspection station 
operator calls up from the computer memory a template specifically created 
for the characteristic being inspected, as indicated in a step 34 of FIG. 
2. Upon retrieving the template in electronic form, the template is also 
displayed on monitor 22, superimposed onto magnified image 40, as recited 
in a step 36 of the process flow of FIG. 2. The template can be called up 
from memory using keyboard 24, and can preferably be accomplished by 
pressing a single key on the keyboard. Existing software programs to 
simplify the key stroke combination necessary to retrieve files or perform 
other computer functions can be used to facilitate recall and display 
steps. 
FIG. 4 is a template image 60 of a template designed for inspecting a wire 
bond configuration for die 42 as it would appear (by itself) on monitor 22 
upon being retrieved from memory. Template image 60 is one of numerous 
template designs which could be used in accordance with the invention. The 
actual template design will depend upon the particular device 
characteristic being inspected. Generally, template image 60, and other 
templates used in accordance with the invention, have two primary 
components; transparent regions 62, and opaque regions 64. Although opaque 
regions 64 (and others illustrated herein) are shown as being 
cross-hatched to meet drawing requirements, preferably the regions are 
solid in color, for example black, to enhance the contrast between the 
opaque regions and transparent regions. Opaque regions 64 are designed to 
hide all portions of the magnified image of the wire bonded device except 
those regions including wire bonds. Thus, transparent regions 62 highlight 
only the wire bonded portions of the device. Upon retrieving the template 
from the computer memory and displaying the template image 60 on monitor 
22, the image of the template is superimposed upon the already existing 
magnified image 40 of the wire bonded device, to create a superimposed 
image 70 as illustrated in FIG. 5. 
Once superimposed image 70 is established on monitor 22, the operator in 
charge of the inspection station compares the magnified image of the 
device and the image of the template, as indicated in a step 38 of the 
process flow of FIG. 2. The result of the comparison step leads to a 
conclusion as to whether the device being inspected is acceptable or 
should be rejected, as indicated by a decision step 39 in FIG. 2. As can 
be seen by FIG. 5, superimposed image 70 provides a very clear image for 
an inspection station operator to view in inspecting for a proper wire 
bond configuration. Wire bonded regions of the device being inspected are 
visible through transparent regions 62 of the template, while other 
regions of the device being inspected are blocked out by opaque regions 
64. Thus, the inspectors attention is focused only on that characteristic 
of the device being inspected, in this case the wire bond configuration. 
There is no point during the inspection process where the examiner has to 
look away from the device being inspected, for example to look at a paper 
wire bond diagram. Thus, the likelihood of the operator losing his or her 
place during the inspection is significantly reduced. As can be seen by 
the superimposed image 70 shown in FIG. 5, the template can be designed to 
hide those leads which are not to include a wire bond by making those 
regions of the template image opaque. Accordingly, an operator can tell in 
an instant whether or not the appropriate leads are wire bonded, and thus 
render a decision as to whether the device should be accepted or rejected. 
It is noted that in some instances a wire bond may exist from die 42 to a 
lead 48, but that the wire bond is not supposed to be there, in which case 
it may be covered by an opaque region of the template. Looking only at the 
superimposed image 70, this wire bond would be hidden, and not visible to 
the inspector. However, the computer system can be configured so that an 
operator can toggle back and forth between viewing only an image of the 
device being inspected and the superimposed image which includes both the 
device being inspected with an overlaying template image. The operator can 
then look for the existence of wire bonds beneath otherwise opaque regions 
of the template to reject the device as being improperly wire bonded. 
Enhancements can be made to template image 60 to further facilitate the 
inspection process. For example, in reference to using a template to 
inspect a wire bond configuration, alpha-numeric characters or symbols can 
be added to the template such as shown in FIG. 6. FIG. 6 illustrates a 
template image 75 much like the template image illustrated in FIGS. 4 and 
5 but which include a series of numbers corresponding to transparent 
sections of the template image. The numbers listed next to each 
transparent section correspond to the number of wire bonds which should be 
included within that region. For example: along the left edge of the die 
there should be thirteen wire bonds; along the bottom side of the die 
there should be fifteen wire bonds; at the bottom right corner there 
should be one isolated wire bond; along the right side of the die there 
should be twelve wire bonds; and along the top edge of the die, there 
should be two segments, one with nine wire bonds and the other with eight 
wire bonds, with an unbonded lead separating these two sections. In 
addition to the wire bond count, alpha-numeric characters can be included 
to denote non-standard bonding arrangements. For example, the locations of 
double bonds, wherein two wires are connected to one lead, can be denoted 
by "Double" or "2W". Similarly, "G" or "GND" can be used to denote that a 
wire is connected to a ground. Caution is advised, however, to avoid 
overcrowding the template image with alpha-numeric symbols. The image that 
the operator must view during inspection should be relatively clear and 
unobstructed for inspecting the characteristic at hand. 
FIG. 7 illustrates an example of using the present invention for inspecting 
a die attached material bondline. Shown in FIG. 7 is a magnified image 78 
of a side view of semiconductor die 42 as it is mounted on flag 44, and 
prior to being wire bonded to leads 48. The die is attached to flag 44 
using a conventional die attach material 43, which for example is a 
silver-filled epoxy. The die attach material creates a bondline 45 along 
each of four sides of the die. The location of the bondline (how far up 
along the die edge or side face the die attached material exists) is 
important, and is usually inspected. Having the bondline too close to the 
flag (i.e. not high enough up the die side) results in an unreliable die 
attachment, while having the bondline too close to the active surface of 
the die creates a potential problem of electrically short circuiting the 
device since the die attach material is usually electrically conductive. 
Accordingly, semiconductor manufacturers set an acceptable range within 
which the bondline can exist. Looking only at a side view of the die on 
the flag makes it difficult for an operator to determine if the bondline 
is appropriately within the accepted range. However, with the help of the 
present invention, this range can easily be incorporated into a template 
which is overlaid or superimposed upon the magnified side view of the die, 
allowing the operator to give a quick "pass" or "fail" conclusion as to 
whether the bondline falls within an accepted range. 
An example of what one suitable template for inspecting a die attach 
material bondline looks like is illustrated in FIG. 8. A template image 80 
has an opaque region 84 and a transparent rectangle 86. Again, opaque 
region 84 is preferably solid in color rather than cross-hatched as shown. 
Rectangle 86 is created to correspond with the top, bottom, and side 
boundaries of the magnified image of the side view of die 42 shown in FIG. 
7. It is noted, however, that the shape of a transparent region used for 
inspecting a die attach material bondline need not be a reactangle. Other 
shapes are likely to be suitable as well. Included within rectangle 86 are 
two opaque lines, specifically an upper limit line 88 and a lower limit 
line 89, as defined by a manufacturer's acceptable bondline height. As an 
example, lower limit line 89 can correspond to a distance of 5 percent of 
the total die height, while upper limit line can correspond to a distance 
of 75 percent of the total die height. Template image 80 is superimposed 
onto the magnified image of the side view of the die 42 to create a 
superimposed image 90, as illustrated in FIG. 9. In superimposed image 90, 
the magnified image of the device as illustrated in FIG. 7 is visible 
within transparent rectangle 86 such that the bondline 45 can be viewed by 
the operator. Because bondline 45 exists below the upper limit line 88 and 
above lower limit line 89, the inspector can immediately determine that 
the device passes inspection. If bondline 45 is not present entirely 
between the two limit lines, the device is rejected. As an alternative to 
limit lines, the transparent rectangle itself could define the upper and 
lower limits for the die attach material bondline. For example, the lower 
edge of the rectangle could serve as the lower limit and the upper edge as 
the upper limit. 
It is noted that in inspecting a die attach material bondline, generally 
one should inspect more than the bondline location on just one side of the 
die. Preferably, the bondline of all four sides of the die are inspected. 
In accordance with the present invention, inspection of all sides can be 
accomplished quite simply by utilizing four cameras (one for each side). 
The magnified image being displayed on the monitor can be rotated around 
the four sides of the device by changing which camera's input signal is 
being displayed on the monitor, without requiring movement of the device 
being inspected. Preferably, the cameras are positioned at angles ranging 
from about 25.degree.-30.degree. from the horizontal plane of lead frame 
and die flag. 
In accordance with yet another embodiment of the present invention, a 
template is used to inspect geometric tolerances of semiconductor package 
leads and marks. Illustrated in FIG. 10 is an image 100 of a leaded, 
packaged semiconductor device from a top view. The device as illustrated 
is a magnified image as it might appear on a monitor in accordance with 
the invention. The device includes a package body 102, a plurality of 
leads 104, and a manufacturer's mark 106. Once the device is encapsulated 
in package body 102, leads 104 are cut from a strip lead frame and formed 
into the desired lead configuration (for example, gull-wing, J-lead, or 
dual-in line). During the cutting and forming operations, and during 
handling operations, the leads can get moved from their original desired 
positions. For instance, as illustrated in image 100, some of the leads of 
the device are skewed (are not perpendicular to the package). Normally, a 
device's leads are not skewed as severly as illustrated. The exagerated 
lead positions are shown for demonstrations purposes. Skewed leads are 
unacceptable because the leads will no longer match the substrate pad 
configuration to which a user will mount the device. Likewise, leads which 
are too short will not be able to match a user's pad configuration. An 
inspection in accordance with the present invention uses a template to 
determine if the extent of lead skew and overall position is acceptable. 
As demonstrated in FIG. 11, a template has opaque portion 111, within which 
are formed transparent squares 112 corresponding to the acceptable limits 
of lead location. There is a transparent square associated with each lead 
of the device. The template is superimposed onto a magnified image of the 
leaded device, and together the template and magnified image of the device 
are displayed on a monitor as a superimposed image 110. Within each 
transparent square 112 is a minimum lead length line 113. Leads lengths 
and other geometric parameters are often set according to industry 
standard. Thus, during an inspection process, minimum lead length line 113 
can be used to make sure each lead is at least a specified length. An 
inspector views each transparent square 112 to make sure each lead 104 
extends to the minimum lead length line 113. To inspect lead skew, 
transparent rectangles are designed and dimensioned such that if any 
portion of the lead touches an edge of the transparent square, the lead is 
too severly skewed and fails the inspection. As illustrated in FIG. 11, 
some leads are illustrated as being too skewed and too short to pass 
inspection, again in an exagerated manner. 
Superimposed image 110 also demonstrates that the present invention can be 
used to inspect geometric tolerances for a manufacturer's product marking. 
Most manufacturer's mark their semiconductor devices with a product 
number, their company logo, and perhaps a manufacturing date code. These 
manufacturers often have strick compliance guidelines for where on the 
device the mark can be placed. A template can be created to account for an 
inspection of the mark placement as well. Superimposed image 110 of FIG. 
11 shows two transparent rectangles 114 within opaque portion 111 which 
correspond to the two lines of alpha-numeric characters constituting a 
mark 106. It is noted that a mark may include any kind of symbol, rather 
than just alpha-numeric characters as illustrated, and may be of any size. 
With a quick look at superimposed image 110, an inspector can instantly 
tell whether the mark is properly placed. 
WORKING EXAMPLE 
Now that the present invention has been described in somewhat general 
terms, a more detailed description of how to actually implement the 
present invention follows. The following description will include 
information pertaining to particular equipment and software which was used 
to establish the present invention, however, the present invention should 
not in any way be limited to the particular configuration and setup herein 
described. Alternative equipment and alternative software can be used to 
accomplish the same objectives and still fall within the scope of the 
present invention. While the following working example is described in 
reference to using the present invention to inspect wire bond 
configurations for semiconductor devices, as noted earlier the present 
invention is not limited to inspecting this particular device 
characteristic. Principles, equipment, and software which are used and 
described in the working example can be extended to a variety of 
inspections needed throughout the semiconductor wafer fabrication and 
assembly process. 
An inspection station for practicing the present invention was built from, 
and based upon, an Allteq Series 3000 inspection station, available from 
Allteq Industries, Fremont, Calif. The Allteq Series 3000 includes both a 
handling system for moving the devices and a microscope. The microscope on 
the Allteq Series 3000 did not have a large enough field of field to view 
the entire wire bonded die and surrounding leads, nor was the microscope 
believed to have sufficient resolution. Therefore, the microscope which 
came with the inspection station was replaced with a Leica Wild M3Z 
microscope. A charge coupled device (CCD) camera was installed on the 
microscope and connected to enable transmission of the magnified image 
created by the microscope to a computer monitor. A high resolution CCD 
camera made by Sony Corporation, Model No. SSC/C374, was found to be 
suitable for this purpose. A Macintosh Quadra, Model 840AV, a computer 
made by Apple Computer, Inc. of Cupertino, Calif., was utilized also in 
the inspection station. The computer was equipped with 24 megabyte of RAM 
(random access memory), a 230 megabyte hard drive, and had built in video 
support (1 Meg Video RAM, upgradable to 2 Meg). The monitor used was a 20 
inch multi-sync monitor, also made by Apple Computer. An output of the CCD 
Camera was connected to an input of the computer to enable the magnified 
image of the device being inspected to be displayed on the monitor. An 
inspection station such as that described above (including the software 
described below) can be set up for a cost in the range of only 
$20,000-$30,000 as compared to fully automated stations which cost in 
excess of $100,000. 
Software which was used to establish the present invention includes Video 
Monitor Version 1.0 and Simple Text Version 1.1.1, by Apple Computer, 
Inc., which comes pre-installed on the Quadra 840AV Apple Computer system, 
Quick Keys Version 3.0 by CE Software, Inc., of West Des Moines, Iowa, 
File Typer Version 4.1.2 (shareware available from Daniel Azuma of 
Sunnyvale, Calif.), and Photoshop Version 2.5.1 by Adobe Systems, Inc., of 
Mountain View, Calif. The Quick Keys software is used to enable an 
inspection station operator to simply press one key on the key board to 
perform a pre-specified task. For example, Quick Keys was used to create 
designated key stroke functions called "Video" and "Template." Upon 
pressing the Video key, a magnified image of the device being inspected as 
visible through the microscope is displayed upon the computer monitor via 
the camera. Upon pressing the Template key, the appropriate template for 
the device being inspected is called from computer memory and displayed on 
the monitor superimposed onto the magnified image of the device being 
inspected. 
The Photoshop software was utilized to create the templates used in 
practicing the present invention. To create the templates, features of 
Photoshop not discussed in the software's user manual (copyrighted 1993) 
were utilized. Accordingly, a discussion of how to use these features to 
create the templates is herein included. The discussion is on a level 
which assumes the reader is familar with using window-type (mouse based) 
computing systems. In carrying out the procedure described below, it is 
helpful to include SimpleText, Photoshop, and Video Monitor in the Apple 
Control menu of the computer system. Also, the following procedure makes 
reference to various tools in the Photoshop toolbox. The reader should 
consult the Photoshop user manual or open the Photoshop application as a 
graphical aid in using the tools described below: 
1. DISPLAY MICROSCOPE IMAGE OF DEVICE ON MONITOR 
Position the device under the microscope to get the desired view and at the 
desired magnification. Transmit the magnified image to the computer 
monitor by selecting "Video Monitor" from the Apple Control menu. The 
desired device view is preferably centered on the monitor, is in focus, 
and occupies a substantial portion, if not all, of the monitor. 
2. TAKE SNAPSHOT OF DEVICE IMAGE 
The image on the monitor can be copied by pressing simultaneously pressing 
"", (also referred to as the Command key) and "C". This is essentially the 
universal copy command in programs for the Macintosh. Copying the video 
image creates a PICT files of the image on the computer desktop. 
3. OPEN PICT FILE FROM WITHIN PHOTOSHOP 
Open Photoshop by selecting "Photoshop" from the Apple Control menu. Within 
Photoshop, choose "Open" from the "File" menu and select the PICT file 
copied to the desktop in Step 2. 
4. SET PHOTOSHOP SETTINGS 
Under the "Mode" menu, select "Indexed Color . . . ". Set the resolution to 
8 bits/pixel. Set Palette to "System". Set Dither to "none." Click OK. 
This greatly enhances resolution of the PICT file image appearing on the 
monitor. 
5. SET COLORS 
In the Photoshop toolbox, set the "Foreground" and "Background" color boxes 
to black, or whatever color is desired for the opaque portions of the 
template to be created. To change the color, click on the Foreground box 
and enter the numerical red, blue, and green equivalents of the desired 
color (e.g. for black set R=0, B=0, and G=0). Do the same to change the 
Background color. For purposes of creating templates in accordance with 
this procedure, the Foreground and Background color are initially set to 
the same value. 
6. ENLARGE IMAGE 
Select the "Full Screen without menu bar" tool from the bottom right corner 
of the toolbox. This centers the PICT file image on the screen and frames 
it in a black background, blocking out extraneous images from the computer 
desktop. Then select the "Zoom" tool from the Photoshop toolbox. Move the 
cursor (which should now look like a magnifying glass) to anywhere on the 
PICT file image and click. This magnifies the PICT file image to the 
original size of the snapshot taken in Step 2, which should correspond in 
size to the image which is transmitted from the microscope to the monitor 
via the camera in Step 1. 
7. CHANGE BACKGROUND TO TRANSENT 
Next, the background color is made transparent. The user manual of 
Photoshop does not explain how to do this. Applicants discovered the 
Background in Photoshop can be changed to transparent as explained in the 
following two steps, although an understanding of why these steps make the 
Background transparent is not understood. 
a. While still in Photoshop and viewing the enlarged PICT file image 
created in Step 6, select "Video Monitor" from the Apple Control menu. 
This step displays a "live" image of the device under the microscope 
(hereinafter called the Video image), rather than the PICT file image. 
b. Now select "Photoshop" from the Apple Control menu. This step reverts 
the image being displayed on the monitor back to the PICT file image, but 
also (unexpectedly) changes the Background color box to be transparent. 
(In other words, what appears in the Background color box should be a 
portion of the Video image, which was the last "window" open on the 
monitor as created in step a. To check to see if this in fact is the case, 
lightly shake the stage of the microscope and see if the image appearing 
in the Background color box moves.) 
The result of performing steps a and b is to have 3 different "layers" open 
at one time: on top is a PICT file image of the device under the 
microscope; next is a transparent background window (as opposed to a more 
conventional white or black background); and on bottom is the Video image 
of the device under the microscope. 
8. PAINT AND ERASE PICT FILE IMAGE 
The PICT file image should appear as the top layer of the 3-layer stack 
described in Step 7. The template will be created by painting and erasing 
this PICT file image as follows. 
a. Select "Air Brush" from the Photoshop toolbox and paint over a portion 
of the image. The paint will be black, or whatever color was selected for 
the Foreground color. The only reason why the entire PICT file image is 
not painted over is to provide a frame of reference for how much of the 
paint to erase in step b. 
b. Select "Eraser" from the Photoshop toolbox. Erase that portion of the 
paint created in step a to create the transparent portions of the 
template. Upon erasing the paint, the Background which is exposed is 
transparent, meaning that the underlying Video image is shown in the 
erased area, being visible through the transparent Background. (Again, to 
test that the image appearing in the erased area is the Video image, shake 
the microscope stage lightly and see if the image in the erased area 
moves). 
c. Repeat steps a and b until the entire template is created. 
The erased area should correspond to that area of the template to be 
transparent, while the remaining painted areas will form the opaque areas 
of the template. It is useful to paint and erase only parts of the 
template at one time (e.g. a third at a time) so that the unpainted 
portions of PICT file image can be used to approximate where the painted 
portions should be erased. However, since the Video image and the PICT 
file image are virtually identical, it is sometimes difficult to tell 
whether the area being looked at is part of the underlying Video image 
(being viewed through a transparent Background) or part of the PICT file 
image. When in doubt, lightly shake the microscope stage. The Video image 
should move. If an area is over-erased (too much has been erased) it's not 
a problem. The area can simply be repainted and erased again. Furthermore, 
the Line tool can be used in place of the Air Brush to paint more 
precisely. 
9. ADD ALPHA-NUMERIC REFERENCES IF DESIRED 
Alpha-numeric labels can be added to the template to aid in the inspection, 
for instance by having a wire bond count, or by indicating a non-standard 
type of wire bond. To add alpha-numerics to the template, select the 
"Type" tool from the Photoshop toolbox. Change the "Foreground Color" in 
the toolbox to a color which will show up on the opaque regions of the 
template. If the opaque regions are black, a text color of green (G=255, 
R=0, B=0) works well. Place the cursor where the label is to be located 
using the mouse, and type in the desired text. 
10. SAVE TEMPLATE 
Once the transparent and opaque regions and alpha-numerics are 
satisfactorily established, save the template by choosing "Save" under the 
File menu, or simultaneously pressing "" (also referred to as the Command 
key) and "S". Saving the template in Photoshop maintains the file format 
as a PICT file. Preferably the saved file is named to correspond to the 
particular device part number or type and inspection characteristic for 
which the template was created to inspect. 
11. CONVERT PICT FILE TO TTXT FILE 
In order for Simple Text to be able to read the template, the template must 
be converted from a PICT format to a readable format, such as ttxt. To 
convert the PICT template, quit the Photoshop application and return to 
the computer desktop. Drag the PICT template that was saved onto the File 
Typer application. Upon doing this, a "File Typer File Editor" window 
appears. In this window, type "ttxt" in the "Creator" box, then click the 
"Change" box. The template will now be saved as a ttxt file. Note that a 
conversion to ttxt format is not necessary if the system using the 
templates is capable of reading Photoshop's PICT files. 
Once a template is created for the device type and characteristic that is 
being inspected, for example as explained in the above procedure, the 
template can be stored in the computer memory of a master system and 
remotely accessed from satellite systems. In practice, it is likely that 
multiple templates, one for each of the characteristics to be inspected 
and for each of the manufacturer's product type to be inspected, will be 
stored on the master system. As previously mentioned, one suitable 
embodiment for the master system includes consisting of the handling 
system (Allteq 3000) equipped with a microscope, a CCD camera (Sony Model 
No. SSC/C374), and a computer system with a monitor and a keyboard (Apple 
Computer Macintosh Quadra 840 AV). Suitable master system software 
includes Simple Text, File Typer, Quick Keys, and Photoshop. Each 
satellite system includes the same hardware. However, it is noted that 
while both the master system and satellite systems include microscopes, 
the microscopes on the two different systems need not be of the same 
caliber. For example, the satellite systems may require better microscopes 
to enable performance of other types of product inspection. For reasons 
explained below, it is not necessary that all master system software also 
be included on the satellite systems. 
Preferably, the creation and storage of templates and the maintenance of 
the master system is controlled by the quality assurance group of the 
semiconductor manufacturer. Satellite stations then access the template 
information from the master system. In using a master-satellite 
combination, one computer system can be used to control access to the 
templates so that modifications or changes cannot be inadvertently made 
and that templates cannot be duplicated. Use of lesser equipped satellite 
systems no only insure tighter control of the templates used and created, 
but also are more cost effective since not all software used need be 
installed on the satellite systems. For example, templates created in 
Photoshop are initially saved as PICT files. The File Typer software can 
be used to convert the templates from PICT files, to ttxt files. With the 
templates in ttxt format, the Simple Text software of a satellite systems 
can read the templates, removing the need to install the Photoshop 
software on the satellite stations. In a preferred form, the satellite 
systems only have Simple Text and Quick Keys software in common with the 
master system. 
At the satellite inspection stations, the operator preferably has options 
for selecting a particular template for the device being inspected. For 
example, one template may be for a 52 leaded plastic leaded chip carrier 
(PLCC) package, while another is for a 64 leaded plastic quad flat pack 
(PQFP) package. The operator needs to be able to select the appropriate 
template. But again, the operator at the satellite station should not have 
the ability to modify or delete the templates from the master system. Once 
the appropriate template is retrieved, and displayed, superimposed onto an 
image of the device being inspected, the inspector performs a comparison 
to see if the device is in compliance with quality standards. 
The foregoing description and illustrations contained herein. demonstrate 
many of the advantages associated with the present invention. In 
particular, it has been revealed that a simple system using inexpensive 
hardware and software can be used to establish an inspection process for 
semiconductor manufacturers which has quick results. An inspection station 
operator need only to look at one image on a computer monitor to, 
determine if the device passes or fails the inspection process. Moreover, 
the image being viewed is simplified and only the characteristic that is 
being inspected is highlighted on the screen. The operators attention is 
focused on the particular area necessary for the inspection, while 
extraneous portions of the image of the device are blocked or hidden by a 
template. The superimposed image on the computer monitor provides a 
pass/reject answer to whether the device passes inspection. The present 
invention is easily incorporated into a manufacturing environment, is 
easily operated by an inspection station operator having even minimal 
computer experience, and is conducive to the manufacturer's goal of 
minimizing the time it takes to complete an inspection. Another advantage 
of using the present invention is that the device being inspected can be 
viewed in full field on the computer monitor, so that neither the device 
nor the inspection equipment need be moved or adjusted to allow inspection 
of the entire device. 
Thus it is apparent that there has been provided in accordance with the 
present invention a method for inspecting a semiconductor device that 
fully meets the need and advantages set forth previously. Although the 
invention has been described and illustrated with reference to specific 
embodiments thereof, it is not intended that the invention be limited to 
these illustrative embodiments. Those skilled in the art will recognize 
that modifications and variations can be made without departing from the 
spirit of the invention. For example, the invention is not limited to 
inspecting wire bond configurations, die attach material bondline 
locations, or lead or mark postions of a semiconductor device. These 
particular inspection processes were described herein as examples of how 
the present invention can be implemented at a variety of inspection points 
throughout the manufacturing process. It is envisioned that other 
inspection stages will also benefit from the present invention. In 
addition, the invention is not limited to the specific hardware or 
software equipment described in the working example. The specific details 
described in the working example were only intended to enable one of 
ordinary skill in the art to readily practice the invention, but is not 
intended to limit the scope of the invention. For example, rather than 
employing a full microscope in conjunction with a camera to display a 
magnified image of the device being inspected on the monitor, a camera and 
magnification lens combination is sufficient. Furthermore, the template 
images need not be permanently stored in the computer's memory, but can 
instead be read or retrieved from a floppy disk or tape. It is also 
important to note that the specific template images illustrated herein are 
not the only template images which can be used in practicing the present 
invention. For example, the template can include various colors intended 
to designate a particular feature of the device, or may include a variety 
of alpha-numeric symbols to aid in the inspection process. Furthermore, it 
is not necessary that both a master system or station and a satellite 
station be used to practice the invention. Therefore, it is intended that 
the invention encompass all such variations and modifications to fall 
within the scope of the appencied claims.