4 inch mask 3 inch wafer 5 inch mask 4 inch wafer 7 inch mask 6 inch wafer NRC Mask Shop: Mask Generation Quick Guide File Design File Conversion Exposure IR Oven Flood Expose Develop Etch Inspection Strip Package Clearfield Darkfield Pass Fail Pass Mask Complete Photomasks have both opaque and transparent areas, which act as the basis of all applications where it is required to accurately transfer images of designed patterns from one medium to another. This photolithographic process relies on UV sensitive chemicals, collectively known as photo resist, which cure when exposed. By systematically exposing photo resist it is possible to create patterns on any substrate, specifically in this case, a photomask. This document will cover the basics of photomask fabrication as well as the important details required for any new design, but for a further explana- tion of the complete photomask design process, please see The Fundamentals of Photomask Design and Fabrication. Right Read - Chrome Up Right Read - Chrome Down Darkfield Clearfield Photomask Tonality There are two basic terminologies used to describe the opacity of both the features and the background of designed patterns. Patterns with transparent features and opaque backgrounds are referred to as being darkfield while patterns with opaque features and transparent backgrounds are referred to as being clearfield. To eliminate confusion that can arise when interpreting design files, it is important to reference tonality to the drawn data in the design file. Photomask Parity Determining the parity can be one of the most confusing design aspects because it is sometimes hard to clearly communicate. For simplicity and standardization, masks should be referenced to by their metalized (“chrome”, “feo”) layer. Mirrored photomasks should be described as “right read chrome down” or “wrong read chrome up” while non-mirrored photomasks should be described as “right read chrome up” or “wrong read chrome down”. As a good rule of thumb, the photo- mask should be mirrored if it will be used to transfer a pattern directly to another substrate. Photomask Sizing Traditionally, in the most common applications, a five (5) inch mask is used to pattern a four (4) inch wafer and, likewise, a four (4) inch mask is used to pattern a three (3) inch or two (2) inch wafer. However, if your application requires sizing outside these bounds, two (2) inch to eight (8) inch substrates can be patterned in the Mask Shop upon request. Realize that additional charges and delays may accumulate with non-standard sizing.
Transcript
NRC Mask Shop: Mask Generation Quick GuideTotal Pattern Dimension in X (um)
Tota
l Pat
tern
Dim
ensi
on in
Y (u
m)
Smallest GapDimension (um)
Smallest FeatureDimension (um)
500um500um 750um750um
Sizing, Spacing, and Critical Dimensions
Mask Size: The dimension of possible writable area. The layout size can not exceed the mask sizeLayout Size: The total pattern dimension of the combined drawn dataSmallest Feature (SF): The smallest drawn data measurementSmallest Spacing (SS): The smallest measurement between drawn dataCritical Dimension: Either the SF or the SS, whichever is smaller. Any critical dimension cannot be smaller than 1 micron.
Consideration for Dicing
The path or channel that separates individual die on a wafer is called a scribe line. These scribe lines are used during dicing as a guide for cutting a full wafer into individual devices. Since a saw is used to cut these pieces, the die need to be separated by enough space and these lines need to continually run across the layout, unobstructed. Test patterns and alignment marks can be placed in the scribe lines, but after
dicing, any feature in the path of scribe line will be nonexistent.
1 2 3
Do’s:-Center design on origin-Close all figures-Scale to “1”. When in doubt, use microns.-Purge file of all unused data.
Contact InfoMarcus Nanotechnology Building Rm: 1252
Design SubmissionSubmit two (2) files: either a .GDSII or a .DFX file and a .CIF file.
Don’ts-Do not use special characters-Do not draw data on top of data-Do not flatten file
Mask Design Do’s and Don’ts
Alignment MarksWhen producing a multi-mask set it is advised to include alignment marks within your design. Because of variances in processing it is recommended to include these “double plus” features across the entirety of the layout, if not in each die individually. The base layer should have female style pluses to accept the male style pluses for each additional layer.
4 inchmask
3 inchwafer
5 inchmask
4 inchwafer
7 inchmask
6 inchwafer
NRC Mask Shop: Mask Generation Quick Guide
File Design File Conversion Exposure
IR Oven Flood Expose
Develop Etch Inspection
Strip
Package
Clearfield
Darkfield
Pass
Fail
Pass Mask Complete
Photomasks have both opaque and transparent areas, which act as the basis of all applications where it is required to accurately transfer images of designed patterns from one medium to another. This photolithographic process relies on UV sensitive chemicals, collectively known as photo resist, which cure when exposed. By systematically exposing photo resist it is possible to create patterns on any substrate, specifically in this case, a photomask. This document will cover the basics of photomask fabrication as well as the important details required for any new design, but for a further explana-tion of the complete photomask design process, please see The Fundamentals of Photomask Design and Fabrication.
Right Read - Chrome Up
Right Read - Chrome DownDarkfield
Clearfield
Photomask Tonality
There are two basic terminologies used to describe the opacity of both the features and the background of designed patterns. Patterns with transparent features and opaque backgrounds are referred to as being darkfield while patterns with opaque features and transparent backgrounds are referred to as being clearfield. To eliminate confusion that can arise when interpreting design files, it is important to reference tonality to the drawn data in the design file.
Photomask Parity
Determining the parity can be one of the most confusing design aspects because it is sometimes hard to clearly communicate. For simplicity and standardization, masks should be referenced to by their metalized (“chrome”, “feo”) layer. Mirrored photomasks should be described as “right read chrome down” or “wrong read chrome up” while non-mirrored photomasks should be described as “right read chrome up” or “wrong read chrome down”. As a good rule of thumb, the photo-mask should be mirrored if it will be used to transfer a pattern directly to another substrate.
Photomask SizingTraditionally, in the most common applications, a five (5) inch mask is used to pattern a four (4) inch wafer and, likewise, a four (4) inch mask is used to pattern a three (3) inch or two (2) inch wafer. However, if your application requires sizing outside these bounds, two (2) inch to eight (8) inch substrates can be patterned in the Mask Shop upon request. Realize that additional charges and delays may accumulate with non-standard sizing.
NRC Mask Shop: Mask Generation Quick GuideTotal Pattern Dimension in X (um)
Tota
l Pat
tern
Dim
ensi
on in
Y (u
m)
Smallest GapDimension (um)
Smallest FeatureDimension (um)
500um500um 750um750um
Sizing, Spacing, and Critical Dimensions
Mask Size: The dimension of possible writable area. The layout size can not exceed the mask sizeLayout Size: The total pattern dimension of the combined drawn dataSmallest Feature (SF): The smallest drawn data measurementSmallest Spacing (SS): The smallest measurement between drawn dataCritical Dimension: Either the SF or the SS, whichever is smaller. Any critical dimension cannot be smaller than 1 micron.
Consideration for Dicing
The path or channel that separates individual die on a wafer is called a scribe line. These scribe lines are used during dicing as a guide for cutting a full wafer into individual devices. Since a saw is used to cut these pieces, the die need to be separated by enough space and these lines need to continually run across the layout, unobstructed. Test patterns and alignment marks can be placed in the scribe lines, but after
dicing, any feature in the path of scribe line will be nonexistent.
1 2 3
Do’s:-Center design on origin-Close all figures-Scale to “1”. When in doubt, use microns.-Purge file of all unused data.
Contact InfoMarcus Nanotechnology Building Rm: 1252
Design SubmissionSubmit two (2) files: either a .GDSII or a .DFX file and a .CIF file.
Don’ts-Do not use special characters-Do not draw data on top of data-Do not flatten file
Mask Design Do’s and Don’ts
Alignment MarksWhen producing a multi-mask set it is advised to include alignment marks within your design. Because of variances in processing it is recommended to include these “double plus” features across the entirety of the layout, if not in each die individually. The base layer should have female style pluses to accept the male style pluses for each additional layer.
4 inchmask
3 inchwafer
5 inchmask
4 inchwafer
7 inchmask
6 inchwafer
NRC Mask Shop: Mask Generation Quick Guide
File Design File Conversion Exposure
IR Oven Flood Expose
Develop Etch Inspection
Strip
Package
Clearfield
Darkfield
Pass
Fail
Pass Mask Complete
Photomasks have both opaque and transparent areas, which act as the basis of all applications where it is required to accurately transfer images of designed patterns from one medium to another. This photolithographic process relies on UV sensitive chemicals, collectively known as photo resist, which cure when exposed. By systematically exposing photo resist it is possible to create patterns on any substrate, specifically in this case, a photomask. This document will cover the basics of photomask fabrication as well as the important details required for any new design, but for a further explana-tion of the complete photomask design process, please see The Fundamentals of Photomask Design and Fabrication.
Right Read - Chrome Up
Right Read - Chrome DownDarkfield
Clearfield
Photomask Tonality
There are two basic terminologies used to describe the opacity of both the features and the background of designed patterns. Patterns with transparent features and opaque backgrounds are referred to as being darkfield while patterns with opaque features and transparent backgrounds are referred to as being clearfield. To eliminate confusion that can arise when interpreting design files, it is important to reference tonality to the drawn data in the design file.
Photomask Parity
Determining the parity can be one of the most confusing design aspects because it is sometimes hard to clearly communicate. For simplicity and standardization, masks should be referenced to by their metalized (“chrome”, “feo”) layer. Mirrored photomasks should be described as “right read chrome down” or “wrong read chrome up” while non-mirrored photomasks should be described as “right read chrome up” or “wrong read chrome down”. As a good rule of thumb, the photo-mask should be mirrored if it will be used to transfer a pattern directly to another substrate.
Photomask SizingTraditionally, in the most common applications, a five (5) inch mask is used to pattern a four (4) inch wafer and, likewise, a four (4) inch mask is used to pattern a three (3) inch or two (2) inch wafer. However, if your application requires sizing outside these bounds, two (2) inch to eight (8) inch substrates can be patterned in the Mask Shop upon request. Realize that additional charges and delays may accumulate with non-standard sizing.
