Stepper Mask

 

Home Up Layout Translation Contact Mask Stepper Mask EBeam Mask

Introduction

The original field size for stepper is 1cm by 1cm. However, the layout will be written in 5X magnification on the mask. In addition, you need to know the masks will be written in bright field or dark field before generate the stepper alignment marks. e.g. contact layer be dark field and metal layer be bright field.

Stepper alignment mark images:

Bright Field layout
Dark Field layout

 

Generating Stepper alignment Marks.

  1. Create a top cell (new layout), called 'TOP' for instead.
  2. Create local alignment mark by type 'stepper' in the CIW as below:

    3. stepper_command.gif (5637 bytes)

  3. The form appear as below.
    Select the Layer to be generated. e.g. metal
    Select 'bright' or 'dark' field. e.g. Bright field for metal layer.

    stepper_form.gif (3298 bytes)

    Click on OK. The bright field mask has generated and look like this.
    Create this mark for each layer by repeat step 2 and 3.

Putting the Die on Top of Alignment Masks

  1. Create 5X instance by click on Create -> Instance...
    Click on Browser and select Library->Cell->View.
    Set the magnification to 5X by change the Mag field to 5 as shown below.

    stepper_crInst.gif (5122 bytes)

     

  2. Mirror the die if necessary.
    The Die pattern will be flipped on the wafer if you don't mirror the die on the top cell layout.
    Most of the users don't mind the flipped pattern on the wafer.

  3. Placing the enlarged die in between the aligement mask.

 

Flatten the Die Layout

Since the out file in CIF format can handle enlarged layout so we need to flattern the die layout.

  1. Select the die layout in the top cell.
  2. Click on shift-f to display all detail of the die.
  3. Click on Edit -> Other -> Flattern...
  4. Select Flatten Mode to desplayed levels.
  5. Click on OK to start flatten.
    6. It may take some time to finished for large layout.

 

Additional Processing

Due to limitation of conversion program of mask writting machine. No layout patterns allowed beyond 49920um in y direction. i.e.

  1. Ymax=49920um, instead of 50000um
  2. Modify flattened layout if necessary.

 

What next ?

  1. Goto CIFOUT page.
  2. Goto Masking in UST.

 

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Last revised: 19 May 2000