ROCHESTER INSTITUTE OF TECHNOLOGY MICROELECTRONIC ENGINEERING Canon Four Levels per Mask Plate Stepper Jobs Dr. Lynn Fuller Webpage: http://people.rit.edu/lffeee Microelectronic Engineering Rochester Institute of Technology 82 Lomb Memorial Drive Rochester, NY 14623-5604 Tel (585) 475-2035 Fax (585) 475-5041 Email: Lynn.Fuller@rit.edu Department webpage: http://www.microe.rit.edu 2-8-2009 Canon_4X1_Masks.ppt

OUTLINE Introduction Chip Design Calculations Mask Example Approach Level 1 Details Level 2,3,4,5,6,7,8,9,10,11,12 Details Results

INTRODUCTION Placing four photo levels on one mask plate can reduce the number of mask plates by a factor of four. This saves time, costs and inventory of masks needed for projects. For example a 12 level mask set for CMOS will require only 3 mask plates. The disadvantage of this approach is that the chip size is limited to 10mm by 10mm compared to 20mm by 20mm for 1 level per plate masks. The stepper jobs are slightly more complicated but once created provide the same overlay and resolution.

CALCULATING SHIFTS TO OVER LAY LEVELS 2,3,4,5 The first layer is placed on the wafer with no alignment. Lets use an example where a chip has its TVPA marks in the center of the chip and the B scope multi-marks are slightly above, and C scope multi-marks are slightly to the left. Center of shot is placed under the center of the optical column 1 2 4 3 1 2 4 3 Level 1 2 4 3 1 2 4 3 1 2 4 3 The Mask from non chrome side Each level is centered +/- 20 mm from the center of the plate Wafer after 1st exposure with blades wide open

CALCULATING SHIFTS TO OVER LAY LEVEL 2 The subsequent layers are aligned by locating the center of the TVPA and multi-marks from the first layer. Then calculating the center of the chip and moving it under the center of the optical column and make the shot. If in the stepper job the TVPA mark is given as X=0 and Y=0 the shot will be made with the 1st level TVPA under the center of the optical column resulting in exposure as shown. To get level 2 (red) to overlay level 1(green) we give x = -4mm and y = -4mm for the TVPA mark location in the stepper job. The stepper will shift the wafer -4 mm in x and -4mm in y when moving the wafer under the center of the optical column. Thus placing the 3rd quadrant (level 2) over the 2nd quadrant (level 1) as desired. 1 2 4 3 1 2 4 3 Level 1 2 4 3 The Mask from non chrome side Wafer after 1st exposure with blades wide open

CALCULATING SHIFTS TO OVER LAY LEVELS 3 To get level 3 to overlay level 1(green) we give x = -4mm and y = +4mm for the TVPA mark location in the stepper job. The stepper will shift the wafer -4 mm in x and +4mm in y when moving the wafer under the center of the optical column. Thus placing the 4th quadrant (level 3) over the 2nd quadrant (level 1) as desired. 1 2 4 3 1 2 4 3 Level 1 2 4 3 The Mask from non chrome side Wafer after 1st exposure with blades wide open

CALCULATING SHIFTS TO OVER LAY LEVEL 4 To get level 4 to overlay level 1(green) we give x = +4mm and y = +4mm for the TVPA mark location in the stepper job. The stepper will shift the wafer +4 mm in x and +4mm in y when moving the wafer under the center of the optical column. Thus placing the 1 st quadrant (level 4) over the 2nd quadrant (level 1) as desired. 1 2 4 3 1 2 4 3 Level 1 2 4 3 The Mask from non chrome side Wafer after 1st exposure with blades wide open

CALCULATING SHIFTS TO OVER LAY LEVEL 5 To get level 5 to overlay level 1(green) we give x = -4mm and y = +4mm for the TVPA mark location in the stepper job. The stepper will shift the wafer -4 mm in x and +4mm in y when moving the wafer under the center of the optical column. Thus placing the 2 st quadrant (level 5) over the 2nd quadrant (level 1) as desired. 1 2 4 3 1 2 4 3 Level 5 6 8 7 The Mask from non chrome side Wafer after 1st exposure with blades wide open

MIXED SUB-CMOS CHIP DESIGN Alignment Keys (Xur,Yur) (X,Y) (X,Y) (X,Y) (X,Y) (X,Y) (0,0)

SMALL CMOS MASK EXAMPLE 8mmX8mm Level 1 nwell Level- 1 Center at -20,20 Level- 4 Center at 20,20 Level 4 PVt Alignment Keys Fiducial Mark Fiducial Mark 0,0 Level 3 stop Level 2 active Level- 2 Center at -20,-20 Level- 3 Center at 20,-20 Keys View from Non-Chrome Side

LARGE CMOS MASK EXAMPLE 10mmX10mm View from Non-Chrome Side Level- 1 Center at -25,25 Level- 4 Center at 25,25 Level 1 nwell Level 4 Vt Fiducial Mark Fiducial Mark Alignment Keys 0,0 Level 3 stop Level 2 active

CALCULATIONS FOR MIXED SUB-CMOS

CALCULATIONS FOR PMOS (SHORTCOURSE)

CALCULATIONS FOR LARGE CMOS TEMPLATE

APPROACH First Level Exposure – cover the 1st, 3rd and 4th quadrants of the mask using the blade position in the shot file. - In the layout file create a block and shift the block CQ/5 mm in X and –CQ/5 mm in Y to center the array on the wafer. - In the process file select 1st Level – no alignment Second level Exposure – cover the 1st, 2nd and 4th quadrants of the mask using the blade position in the shot file. -no shift in the layout file (Otherwise same as level 1) - Shift the PA and Fine Alignment Mark positions on page 4 and 13 of the process file Third level Exposure – cover the 1st, 2nd and 3rd quadrants of the mask using the blade position in the shot file. -no shift in the layout file

BLADE POSITIONS FOR SHOT FILES LEVEL 1 2nd Quadrant LEVEL 2 3nd Quadrant LEVEL 3 4nd Quadrant LEVEL 4 1st Quadrant BL -10mm BR 10mm BU BD Level 1 Bu = +10 mm Br = 0 mm Bl = -10 mm (0,0) Bd = 0 mm Blade positions are in mm referenced at the wafer.

1st LEVEL LAYOUT FILE #### LAYOUT EDITOR (File ID)### (page-1) File name; 1. Comment; #### LAYOUT EDITOR (File ID)### (page-2) 1. Matrix Invalid Area: 2. Step Size; Sx = Sy = 3. Matrix; Clm = Row = 4. Origin; X= Y= 5. Reticle Table Name ; Lmixed4X1_nwell anything you want 13 mm 8.2 mm 8.2 mm 14 14 0 mm 0 mm RF012subcmos On page 2 you can create and shift blocks

1ST LEVEL LAYOUT CREATE AND SHIFT BLOCK Select Function Key “Modify” Select Function Key “Other Menu” Select Function Key “Shift Copy Block” Select Function Key “Add Block” Row * Column * Go Go Sure? 1 = Yes Select Function Key “Shift Block” X = 4mm Y = -4mm Clear Block 1 = Yes Exit Save

1st LEVEL - PROCESS FILE #### PROCESS EDITOR (File ID)### (page-1) File name; 1. Comment; 2. Alignment Sequence: 1st Mask or AGA …. 3. TTL Alignment Mode (none, I-line or HeNe/B2) 4. TV PA Measurement Mode; #### PROCESS EDITOR (Reticle ID)### (page-2) 1. Reticle ID #### PROCESS EDITOR (Fine Reticle Alignment)### (page-3) 1. Fine Align Tol xy = Theta = Lmixed4X_nwell/PFmixed4X_nwell anything you want, like: second level active 1st Mask HeNe/B2 PA Nwell 0.03 µm 0.03 µm The Process file has 36 pages, only highlighted pages can be accessed, if AGA in item 2 page 2 is selected then page 4 is highlighted and gives row and column and x,y location of the prealignment marks. If alignment mode HeNe is selected page 13 gives the x&y coordinates of the fine alignment marks, if I-line was selected then pg 10&11give fine alignment mark locations, if 1st Mask is selected page 4 to 36 are bypassed.

2ND 3RD 4TH LEVEL PROCESS FILE This process file does alignment to 2 TVPA marks and then looks at 4 locations for fine alignment. It uses Broad-Band illumination and 20P-4F multi-marks. Page –17 1. Number of sample shots (2,4,6,8,12,16) Main; 4 Preliminary ; 4 2. AGA for first wafer ; AGA AGA for 2nd and more wafer ; AGA Page –19 Limit of x or y difference ; 0.5µm (default=0.2µm, can be as large as 9µm) Page –1 Alignment Mode 2. Alignment Sequence Mode; AGA 3. TTL Alignment mode. ; HeNe-TV 4. TV PA Measurement Mode ; PA Page –4 L) Shot : clm= ? row= ? PA Mark Position; Xlp=QPAX mm Ylp= QPAY mm R) Shot : clm= ? row= ? PA Mark Position; Xrp=QPAX mm Yrp= QPAY mm Page –13 AA Mark Position; B: X=BF2X mm Y = BF2Y mm C: X=CF2X mm Y = CF2Y mm Brot X=0 Y=0 AA Mark Pattern ; 20P-4F Mark Condition ; Island Wafer Surface Condition ; 0 Page –15 AA illumination Mode ; Mode-3 C1…. R1….

2ND LEVEL OVERLAY VERIFICATION Mixed Sub-CMOS Product

OVERLAY VERIFICATION FOR BIG CMOS Level 4 VT Level 3 Stop Level 2 Active

EXAMPLE FILE NAMES Small (< 8mm) CMOS Chips Stepper Job Layout File Shot File Process File Reticle Table Reticle ID mixed4x1_nwell Lmixed4x1_nwell Smixed4x1_nwell Pmixed4x1_nwell Rmixed4x Mixed4x1 Mixed4x1_act Lmixed4x1_act Smixed4x1_act Pmixed4x1_act Mixed4x1_stop Lmixed4x1_stop Smixed4x1_stop Pmixed4x1_stop Mixed4x1_vt Lmixed4x1_vt Smixed4x1_vt Pmixed4x1_vt Mixed4x1_poly Lmixed4x1_poly Smixed4x1_poly Pmixed4x1_poly Note: mixed4x1_nwell is 1st level no alignment, quadrant 2 and Mixed4x1_poly is level 5, 9 etc., with alignment, quadrant 2

EXAMPLE FILE NAMES Metal Gate PMOS and Shortcourse Jobs Stepper Job Layout File Shot File Process File Reticle Table Reticle ID L082SHORT4X_DIFF S082SHORT4X_DIFF P082SHORT4X_DIFF Rmixed4x Mixed4x1 L082SHORT4X_OX S082SHORT4X_OX P082SHORT4X_OX Mixed4x2 L082SHORT4X_CC S082SHORT4X_CC P082SHORT4X_CC Mixed4x3 L082SHORT4X_M S082SHORT4X_M P082SHORT4X_M Mixed4x4 END Note: L082SHORT4X_DIFF is 1st level no alignment, quadrant 2

EXAMPLE FILE NAMES Large (< 10mm) CMOS Chips Stepper Job Layout File Shot File Process File Reticle Table Reticle ID F083ADC_nwell LF083ADC_nwell SF083ADC_nwell PF083ADC_nwell Rmixed4x Mixed4x1 F083ADC_act LF083ADC_act SF083ADC_act PF083ADC_act Mixed4x2 F083ADC_stop LF083ADC_stop SF083ADC_stop PF083ADC_stop Mixed4x3 F083ADC_vt LF083ADC_vt SF083ADC_vt PF083ADC_vt Mixed4x4 F083ADC_poly LF083ADC_poly SF083ADC_poly PF083ADC_poly Note: F083ADC _nwell is 1st level no alignment, quadrant 2 and F083ADC _poly is level 5, 9 etc., with alignment, quadrant 2

/shared/cmostestchip2007/CMOS4XTEMPLATE 9.8mm X 9.8mm CHIP TEMPLATE Template for CMOS4Xdesigns Each cell is 800 µm x 800µm Entire Chip is 9800µm x 9800µm Lower Half has Process Verification Test Structures. There is a 200µm street between quadrants on the testchip This is the largest chip that can have 4 masks per plate. /shared/cmostestchip2007/CMOS4XTEMPLATE

EXAMPLE OF A MEBES PLOT JOB 12 cm 2/25/09 9:12:23 MEBES 967 REV, 4.6 SPECIFICATION FILE: JOB:SHORT.JB DTITLE: CMOS FOUR LEVELS / PLATE ITITLE: BARCODE MTITLE: LEVELS 1,2,3,4 CASSETTE TYPE ID:14 LEVEL PLOTTED: 1 JOB SCALE: 1 JOB SCALE: 1.000000 ADDRESSING: 0.500000 MICRONS PLOT SCALE: 1.00 TO 1 CM ID PATTERN X DIMENSION Y DIMENSION PLACEMENT ORIENTATION TONE 1. NWELL.01 25000.00 25000.00 UNMIRROR UNMIRROR NORMAL 2. ACTIVE.01 25000.00 25000.00 UNMIRROR UNMIRROR NORMAL 3. STOP.05 25000.00 25000.00 UNMIRROR UNMIRROR NORMAL 4. VT 25000.00 25000.00 UNMIRROR UNMIRROR NORMAL LAYER 1,2,3,4 CMOS 4 LEVELS / PLATE LVL 1 LVL 4 Y Axis LVL 2 LVL 3 BARCODE 0.0 0.0 X Axis 12 cm

CREATE A MEBES JOB DECK SLICE EDIT, 14 14 means 5” by 5” glass OPTION AA=0.5, BA=0.5, PA, SA=250, VA=10 REPEAT A, 10 STITLE A, 10000, 10000, MEBES III SN @S MTITLE 1, NWELL MTITLE 2, ACTIVE MTITLE 3, STOP MTITLE 4, PMOS VT MTITLE 5, POLY MTITLE 6, LDD N MTITLE 7, LDD P MTITLE 8, N DS MTITLE 9, P DS MTITLE 10, CONTACT MTITLE 11, METAL DTITLE A, SUBMICRON CMOS CHIP 1,(A,RITLOGO-50-01) ROWS 10000/63500 CHIP 2,(A,FIDUCIA-LS-01) ROWS 63500/63500 CHIP 3, $ (1R,EMCR650-01-01), $ (2,EMCR650-01-02), $ (3,EMCR650-01-03), $ (4,EMCR650-01-04), $ (5,EMCR650-01-05), $ (6,EMCR650-01-06), $ (7,EMCR650-01-07), $ (8,EMCR650-01-08), $ (9,EMCR650-01-09), $ (10,EMCR650-01-10), $ (11,EMCR650-01-11) END SLICE EDIT, 14 14 means 5” by 5” glass OPTICON AA=0.5, BA=0.5, PA, SA=40, VA=10 AA means address all levels = 0.5 µm BA means beam size all levels = 0.5 µm PA means all levels positive resist SA means all levels spot current 40 nA VA means all levels acceleration = 10KV MTITLE 1, ADV-CMOS STI DTITLE A, RIT EMCR650 ITITLE A, BARCODE ORIENT A, ITITLE, TITLEROT=90, LOC= CHIP1, (1,cmostestchip-LVL-01, RC=15), first level of cmostestchip maskset END

REFERENCES Robert Manley process improvement project. Germain Fenger process improvement project. 3. Fuller, Lynn Introduction to Reduction Steppers. Rochester Institute of Technology, 2002 4. FPA-200i1 Maintenance Training: Basic Operations Manual, Canon USA Chuck Smith, MicroE Alumni 1987, Applications Engineer, Canon USA, Inc. 804-328-6620x203, csmith@cusa.canon.com Bill Cooman, Canon Equipment Engineer, Maintains the RIT Canon FPA 2000-i1