No. HDM20170309-NS-01 General low temp. curable PI in HDMS Procedure for process setup and process margin Technology Development Center Hitachi Chemical DuPont MicroSystems HD MicroSystems Confidential Info. 1 Chapter 1: Procedure for process setup HD MicroSystems Confidential Info. 2 1. Items for process optimization At prebake process - Appearance - Film thickness - Uniformity At exposure/development process - Film retention* (Determine optimal exposure dose region) - Pattern appearance ( Check defects such as delamination, residue or crack) - Pattern CD ( Check mask size vs. patterned size) * Film retention is ratio of developed thickness / prebaked thickness. HD MicroSystems Confidential Info. 3 2. XP-7100-B1 typical flow for process optimization Step1. Coating and prebake (1-1) Check appearance & uniformity NG Optimize coating recipe or prebake conditions (1-2) Check film thickness NG Optimize coating speed&time Step 2. Exposure Split exposure dose Step 3. Development (3-1) Measure film thickness at each exposure dose (3-2) Check pattern appearance at each exposure dose (delamination, Residue, Crack etc.) (3-3) Check pattern CD at optimum exposure dose NG 1. Create film retention curve to check exposure dose. 2. Optimize dev. time, prebake conditions or exposure dose. NG Step 4. Cure HD MicroSystems Confidential Info. 4 3. Process flow details Step 1 Prebake Coat PI on wafer with tentative spin speed to check uniformity and film thickness. Apply 105ºC/120sec + 115ºC/120sec as prebake conditions tentatively. (1) Check appearance and thickness uniformity a. Check film appearance and thickness uniformity along with measuring film thickness after prebake. b. If thickness uniformity is not good, coating recipe or prebake condition is necessary to be tuned. (2) Check film thickness File thickness (um) a. If prebaked thickness does not meet to the target, adjust it by changing coating spin speed. b. Spin-curve shown in page 12 helps to determine optimal spin speed. Target thickness Optimum coating speed Coating speed (rpm) Fig. Example of coarting speed vs. film thickness HD MicroSystems Confidential Info. 5 Step 2 Exposure Split exposure dose on a coated wafer by using stepper. In the case of using aligner, expose several wafers with different exposure dose to check optimal exposure dose. Exposure dose X mJ/cm2 Wafer A 2X mJ/cm2 Wafer B 3X mJ/cm2 Wafer C Exposure dose : split Focus : 0um Fig. Exposure method 1(Stepper) Exposure does and focus can be changed on a wafer. Fig. Exposure method 2(Aligner) Several wafers are needed to optimize exposure dose by aligner. HD MicroSystems Confidential Info. 6 Step 3 Development Develop exposed wafer(s) by the tentative development time(10 + 10sec, double puddle) 1) Measure film thickness a. Measure film thickness after development at each exposure dose. b. Create film retention curve (exposure dose vs film retention) and estimate optimal exposure region where film retention is constant (See below figure). 2) Check pattern appearance a. Check whether there are defects such as delamination, residue or crack at each exposure dose or not. b. If defects are observed, adjust conditions of prebake and development with changing exposure dose over and over. 3) Check pattern CD a. Measure and check pattern CD to see whether it is acceptable or not. * Film retention (FR) Film retention(%) - FR(%) = Film thickness after dev. / Film thickness after prebake x 100 - Target exposure dose is region to obtain stable FR after development. - Too low or too high exposure dose may give defects such as delamination, residue or crack. Too low dose Ideal region Too high dose Exposure dose(mJ/cm2) Fig. Image of film retention curve HD MicroSystems Confidential Info. 7 ４. Typical process conditions (Film thickness= 7,10um) Conditions Process unit Remark Pre-spin Coating @7um target @10um target 1000/10 1000/10 - 2800/30 2000/30 - Machine rpm/sec Main-spin Prebake ºC/sec Film thickness after prebake um Exposure (i-line stepper) mJ/cm2 PEB (Post Exposure Bake) 105/120+115/120 9.7 ACT8(TEL) Hot plate 12.9 - - 400-600 - FPA-3000iw (Cannon) ºC/sec Not required (Apply as necessary) Hot plate Development (2 step puddle) sec 10+10 PA-401D 1) Rinse (Spray/stream) sec 10 PA-400R 2) Film thickness after development um Final Cure ºC/h 7.9 11.1 200/2 1) 2) ACT8(TEL) - - under N2 gas u-TF (Koyo) Developer: Cyclopentanone Rinse:Propylene glycol monomethyl ether acetate HD MicroSystems Confidential Info. 8 5. Typical coating and development recipe Example of coating recipe Step Spin speed Spin time (rpm) (sec) Example of development recipe Chemical Function Step Spin speed Spin time (rpm) (sec) Chemical Function 1 0 1 1 200 2 2 30 5 2 50 6 3 0 5 Dispense 3 0 4 1000 10 Pre spin 4 1000 3 5 X Y Main spin 5 50 6 6 800 2 6 0 7 800 3 BR-31) Back rinse 7 1000 8 8 1200 5 BR-3 1) Back rinse 8 800 10 PA401D+PA400R Over rap rinse 9 1200 5 9 2000 10 PA400R 3) Rinse 10 2000 3 10 3000 20 PI Z Z PA401D 2) 4) 1st dispense 1st puddle PA401D 2) 4) 2nd dispense 2nd puddle Spin dry 1) Back rinse:BR-3 (Methanol/DMF(Dimethylformamide) =25/75) or cyclopentanone 2) Developer: Cyclopentanone 3) Rinse: Propylene glycol monomethyl ether acetate 4) Standard is 10sec. In the coating recipe, X (main coating speed) or Y (main coating time) is tuned to meet target thickness after prebake. In the development recipe, Z(puddle time) is tuned with checking performance after development. HD MicroSystems Confidential Info. 9 6. Film retention 100 Film retention (%) 90 80 70 60 i-line 50 B.B 40 30 0 200 400 600 800 1000 1200 Exposure dose (mJ/cm2) Prebake conditions: 105ºC/120sec + 115ºC/120sec Exposure: i-line stepper and broad band aligner Film retention: Developed thickness / Prebaked thickness X100(%) (Thickness:12.9um 10um after cure @200ºC/2h) HD MicroSystems Confidential Info. 10 7. Example of nozzle moving program at development Nozzle moving program can be changed with checking performance (CD uniformity, residue etc.). Wafer edge Wafer center Wafer edge Dispense start Time Dispense end Center P1 Fig. Rough image of nozzle moving during developer dispense HD MicroSystems Confidential Info. 11 8. Film thickness curve Spin time= 30sec 20 20 Film thickness (um) Prebake Development Cure 15 Film thickness (um) Spin speed= 2000rpm 10 5 Prebake Development Cure 15 10 5 0 0 10 1000 1500 2000 2500 3000 20 3500 30 40 50 60 70 Spin time(2000rpm/X sec) Spin speed (X rpm/30sec) Coating conditions vs Film thickness Prebake conditions: 105ºC/120sec + 115ºC/120sec Exposure: 500mJ/cm2 Cure: 200ºC/2h HD MicroSystems Confidential Info. 12 Chapter2: Process margin data HD MicroSystems Confidential Info. 13 1. Tips for getting suitable process margin If cross-linking reaction is not enough after exposure, holding time between exposure and development is needed (See page 15-17). [Holding time more than 0.5hr after exposure is needed and 1-3hr is more preferable.] Split prebake temperature (e.g. +/- 5C or 10C) and exposure energy at the same time(See page 20-21). General low temp. curable PI in HDMS is designed to be dissolved with developer easily. 10-20sec of puddle time would be enough(See page 24, 25). [ e.g. (Dispense time 10-15sec +puddle time 10-20sec) x 2 ] If delamination and/or residue still emerge due to insufficient cross-linking reaction, PEB (6090C/60sec) is one of the options to promote cross-linking reaction. If the rinse is conducted immediately after development, there is a potential of residue by precipitation of the dissolved film. The rinse by mixture of developer and rinse is highly recommended to avoid residue formation (See page 9, development recipe: step 8-9) . [Recommendation: 1.Development 2.Rinse (developer + rinse) 3.Rinse ] * * Developer: Cyclopentanone, Rinse: Propylene glycol monomethyl ether acetate) HD MicroSystems Confidential Info. 14 2. Impact of holding time between exposure and development 100 Film retention(%) 90 80 400mJ/cm2 500mJ/cm2 70 600mJ/cm2 60 0 2 4 6 Holding time (hr) 8 10 12 Holding time vs Film retention Prebake conditions: 105ºC/120s + 115ºC/120s Prebaked thickness: 13um, Exposure: i-line stepper Development:10sec+10sec Holding time after prebake: 1hr Holding time (between exposure and development) more than 0.5 hour is necessary and 1-3 hours are preferable. HD MicroSystems Confidential Info. 15 2. Impact of holding time between exposure and development 30 10um via pattern 20um via pattern CD size(um) 25 20 15 10 5 0 0 2 4 6 Holding time (hr) 8 10 12 Holding time vs CD size Prebake conditions: 105ºC/120s + 115ºC/120s Prebaked thickness: 13um Development:10sec+10sec Holding time after PB: 1hr Exposure dose : 500mJ/cm2 Holding time(between exposure and development) more than 0.5 hour is necessary and longer holding time doesn’t impact on CD size. 1-3 hours holding time is preferable. HD MicroSystems Confidential Info. 16 2. Impact of holding time between exposure and development Holding time (min) Exposure dose (mJ/cm2) 500 (HDM standard) 300 Delamination Residue 700 Delamination Delamination 5 Delamination and residue 60 Slight delamination Slight delamination - - Delamination (HDM standard) Slight delamination Prebake: 105ºC/120sec + 115ºC/120sec, Exposure : i-line stepper, Development time: 10sec +10sec, Holding time after PB: 1h Enough holding time or exposure dose is needed to avoid delamination and/or residue. To conduct PEB (60-90ºC/60sec) is one of the options to shorten holding time between exposure and development. HD MicroSystems Confidential Info. 17 2. Impact of holding time between prebake and exposure 100 Film retention(%) 90 80 400mJ/cm2 500mJ/cm2 70 600mJ/cm2 60 0 2 4 6 Holding time (hr) 8 10 12 Holding time vs Film retention Prebake condition: 105ºC/120s + 115ºC/120s Prebaked thickness: 13um, Exposure: i-line stepper Development:10sec+10sec Holding time after exposure: 1hr Holding time between prebake and exposure doesn’t impact on film retention. HD MicroSystems Confidential Info. 18 2. Impact of holding time between prebake and exposure 30 10um via pattern 20um via pattern CD size (um) 25 20 15 10 5 0 0 4 8 12 Holding time (hr) Holding time vs CD size Prebake conditions: 105ºC/120s + 115ºC/120s Prebaked thickness: 13um Development:10sec+10sec Holding time after exposure: 1h Exposure dose: 500mJ/cm2(I line) Holding time between prebake and exposure doesn’t impact on CD size. HD MicroSystems Confidential Info. 19 3. Impact of prebake condition (Film retention) Exposure dose vs Film retention PB temp. vs Film retention 100 Film retention(%) Film retention(%) 100 90 80 X = -5 ℃ X= 0℃ X = +5 ℃ 70 60 90 80 70 400mJ/cm2 500mJ/cm2 600mJ/cm2 60 50 50 X = -5 200 300 400 500 600 Exposure dose(mJ/cm2) X=0 X = +5 700 Prebake temp. (ºC) Prebake conditions: (105 + X) ºC/120sec +(115 + X) ºC/120sec Development: 10sec + 10sec Film retention: (Developed thickness/ Prebaked thickness) x 100 Target thickness: 10um after cure Higher prebake temperature tends to lower film retention. 20 3. Impact of Pre-bake condition (Resolution and CD size) Exposure dose vs resolution(open mask size) PB temp. vs CD size 20 X = -5 ℃ X= 0℃ X = +5 ℃ 15 CD size (um) Resolution (um) 20 10 5 15 20um via mask 400mJ/cm2 500mJ/cm2 600mJ/cm2 10 5 10um vis mask 0 200 300 400 500 600 Exposure dose(mJ/cm2) 700 0 X= -5C X= 0 X= +5 Change of PB temp. (℃ ) Prebake conditions: (105 + X) ºC/120sec +(115 + X) ºC/120sec Development: 10sec + 10sec Target thickness: 10um after cure The change of prebake temperature doesn’t impact on resolution and CD size. 21 3. Impact of prebake conditions (Pattern profile) Prebake condition (105-5)C/120sec + (115-5)C/120sec 105C/120sec + 115C/120sec (105+5)C/120sec + (115+5)C/120sec Prebake conditions: (105 + X) ºC/120sec +(115 + X) ºC/120sec Development: 10sec + 10sec Cure: 200C/2h Exposure dose: 500mJ/cm2 Mask size: 10um, 100um No significant change of pattern profile is observed even at different PB temperature. 22 4. Impact of development conditions (Film retention) Development time vs Film retention Exposure dose vs Film retention 90 90 80 Y= -5 sec Y= 0 sec Y= +5 sec Y +10 sec 70 60 50 Film retention(%) 100 Film retention(%) 100 80 70 400mJ/cm2 500mJ/cm2 60 600mJ/cm2 50 200 300 400 500 600 Exposure dose(mJ/cm2) 700 Y= -5 Y= 0 Y= +5 Y= +10 Change of Development time (sec) Development: (10 + Y)sec + (10 + Y)sec Prebake conditions: 105ºC/120sec +115ºC/120sec Film retention: (thickness after dev./thickness after prebake) x 100 Target thickness: 10um after cure There is no big difference for FR by changing development time. 23 4. Impact of development conditions (Resolution and CD size) Development time vs CD size Exposure dose vs resolution(open mask size) 20 Y = -5 sec Y = 0 sec Y = +5 sec Y = +10 sec 15 15 CD size(um) Resolution (um) 20 10 5 0 20um via mask 400mJ/cm2 500mJ/cm2 600mJ/cm2 10 5 10um via mask 0 200 300 400 500 600 Exposure dose(mJ/cm2) 700 Y = -5 Y=0 X = +5 X = +10 Change of development time (sec) Development: (10 + Y)sec + (10 + Y)sec Prebake condition: 105ºC/120sec +115ºC/120sec Target thickness: 10um after cure There is no big difference for resolution and CD size by changing development time. 24
