Standard Operating Manual

Transcription

1 Standard Operating Manual LAM490 AutoEtch System Copyright by Hong Kong University of Science & Technology. All rights reserved. Page 1

2 Contents 1. Picture and Location 2. Process Capabilities 2.1Cleanliness Standard 2.2 Possible Etching Materials 2.3 Process Specification 2.3.1What the LAM490 CAN do What the LAM490 CANNOT do 2.4 Etching Process Useful Information 3. Useful information to work in NFF 3.1 Emergency Responses and Communications 3.2Become a Qualified LAM490 User 4. Operating Safety and Rules 4.1 Operation Safety 4.1.1General Safety Equipment Safety 4.2 Operation Rules 5. System operation 5.1 LAM490 System Description 5.2 Initial Status Check 5.3 Initial System Check 5.4 Preparation before Etching Process Gas Supply Wafer Alignment Preparation 6. Introduction to LAM490 operation control system 6.1 Load and Edit Recipe Load a Recipe Edit a Recipe Edit end point parameters Signal Options Page 7. Auto Process Run 7.1 Set Wafer Cassette 7.2 Send and Load Wafer 7.3 Pump down and Wafer loading 7.4 Run etching recipe 7.5 Unload Wafer 7.6 Return Wafer 7.7 Chamber Clear 8. Process Recording 9. Clean up 10. Check out Appendix Copyright by Hong Kong University of Science & Technology. All rights reserved. Page 2

3 LAM 490 AutoEtch System 1. Picture and Location Fig.1 LAM 490 AutoEtch System The LAM 490 AutoEtch System is located at NFF Phase II cleanroom, Room Process Capabilities 2.1 Cleanliness Standard The LAM490 AutoEtch system is being classified as CLEAN equipment. 2.2 Possible Etching Materials Poly-Silicon, nitride, α-si film. Silicon mark. Copyright by Hong Kong University of Science & Technology. All rights reserved. Page 3

4 2.3 Process Specification The masking material can be photo-resist prepared in CLEAN standard equipment What the LAM 490 CAN do Individual 4 inches full silicon or quartz substrate in CLEAN cleanliness standard What the LAM490 CANNOT do Substrate not in 4 inches in diameter The films that not in the list. Defect appearance of the substrate. Fragile appearance of the substrate. Appearance of the photo-resist is not well baked. Appearance of the photo developer on the back side of the substrate. Substrate appears will generate particles during etching process. Photoresist that coated on the backside of the substrate. 2.4 Etching Process Useful Information Before starting your etch process, please make sure a dummy condition run must be performed in order to ensure the stability of the equipment. The typical etch rate for silicon nitride film is around 900A/min, selectivity to oxide is around 3.5, and selectivity to photoresist is 1.5. The typical etch rate for polysilicon film (SF6) is around 4500A~6500A/min, selectivity to oxide is around 20, and selectivity to photoresist is 3. However, the etching uniformity of polysilicon film is not good, ~10%. The typical etch rate for polysilicon film (Cl2) is around 5000A/min, selectivity to oxide is around 30, and selectivity to photoresist is 2. However, the etching uniformity of polysilicon film is not good, ~10%. The typical 1200A silicon mark etching time is 26~30 seconds. However, please pay special attention to the existing native oxide, and also a descum process will be recommended after lithography processes. In addition, not less than 5 dummy wafers must be performed in order to get a stable etching rate. Copyright by Hong Kong University of Science & Technology. All rights reserved. Page 4

5 For more details information about the process of LAM490, please consult NFF etching module staffs. For recipe details, please check the appendix attached. 3. Useful information to work in NFF 3.1 Emergency Responses and Communications In case of emergency issues, please contact NFF staffs, Preason Lee Deputy Safety office (x7900). CK Wong senior technician (x7226). In case of technical help, please contact NFF staffs, CK Wong senior technician (x7896). Casper Chung technician (x7896). Brial Kwok technician (x7896). 3.2 Become a Qualified LAM490 User Please follow the procedures below to become a qualified user of LAM490: Read all materials provided on the NFF website about the LAM490. Request the LAM490 operation training and examination online. 4. Operation Safety and Rules 4.1. Operation Safety General Safety LAM490 user must familiar themselves with the following general safety issues: Location of emergency exits and assembly points Procedures for obtaining first aid assistance must be known. Various alarm sounds and emergency call procedures must be known Equipment Safety LAM490 user must be aware themselves of the following equipment safety issues: Copyright by Hong Kong University of Science & Technology. All rights reserved. Page 5

6 In emergency when using the equipment, please turn the POWER button off (Fig. 2) to interrupt the equipment power, and report to the NFF staffs immediately. DO NOT attempt to resume the equipment on before the problem is solved. In case there is gas leakage from the equipment and hazard alarm sounds, leave the cleanroom immediately after pushing the emergency button. DO NOT attempt to collect any substrates or belongings. If the equipment fails while being used, never try to fix the problem by your own, please write down the alarm information and report to NFF etching module staffs. Alarm/warning message will be shown in the control screen (Fig.3). DO NOT attempt to resume the equipment on before the alarm/warning message is verified. Be careful to the components of the equipment, which involves electric power, RF radiation and high temperature hazard. Fig 2 Emergency Power button Copyright by Hong Kong University of Science & Technology. All rights reserved. Page 6

7 Fig.3 Alarm/Warning message 4.2 Operation Rules Do not operate the equipment unless you are properly trained and authorize to operate the equipment. Reserve the equipment in NFF website in advance. Reservation will be forfeited if user never shows up and check-in within half of the session time and it may cause a $200 penalty. Fill all the details of the log-sheet attached, i.e. date, name, project number, , project details, material Do not leave an on-going etching process unattended. Do not skip any pump and purge steps during process running. Do not change details of the recipe unless you are authorized to do. If you need to start a new recipe, please consult NFF etching module staffs. Copyright by Hong Kong University of Science & Technology. All rights reserved. Page 7

8 5.0 System Operation 5.1 LAM490 System Description The Lam490 AutoEtch System is fully automated; etching single wafers using plasma dry etch process. This equipment includes loadlock transport system, and process chamber. A loadlock transport system consists of send/receive cassette indexers, belt drive system, entrance/exit lifters, entrance/exit arms, and entrance/exit loadlocks. The process chamber consists of electrode assembly; electrode gap drive, gas delivery system and RF match system. The electrode gap drive provides space adjustment between the upper electrode and the wafer, which provides a wider process window. The gas delivery system employs different kind of process gases, including He, O2, Cl2, SF6 and C2F6. Typically, Cl2 gas can be used for poly-silicon etch, SF6 can be used for silicon, poly-silicon, and nitride etch. On the other hand, C2F6 can be used for native oxide removal or process chamber cleaning. Then RF matching assembly automatically matches the impedance of the chamber to the RF generator, according to different setting of RF power, electrode gap spacing, gas mixture, and chamber pressure. 5.2 Initial Status Check Users are required to do the following checks before doing the etching process: Please check the equipment status from the shutdown notice board in the NFF reservation website. If the equipment has been reserved, then check the user name and project number that displayed on the dedicated LCD screen are correct (Fig. 4). Please check-in the reserved equipment on your own within half of the session time. To do the check-in, please scan your NFF access card over the card reader attached. After checked-in the equipment, the red LED on the card reader will be ON. If you are failed to do the check-in, there is an interlock, and you cannot operate the equipment normally. Before operate the equipment, make sure you have read and ready to fill the details of Copyright by Hong Kong University of Science & Technology. All rights reserved. Page 8

9 the log-sheets attached. Fig.4 Reservation and Equipment check-in status LCD 5.3 Initial System Check Turn on the CRT display if necessary. Check any wafer left in the cassette of entry/exit load lock. Check the base pressure is below 0.05Torr (Fig. 5). Otherwise, please contact NFF staffs for help. Please check the chiller is running. The default temperature is 20 o C and default resistance of the DI water circulate is 15Mohm (Fig.6) Visual check any water leakage from the equipment. Check any abnormal sound coming from the equipment. Check there is no alarm/warning message displayed in the main control screen. Copyright by Hong Kong University of Science & Technology. All rights reserved. Page 9

10 Fig.5 base pressure reading Fig.6 Water chiller 5.4 Preparation before Etching Process You are advised to do the following steps before start do the etching process Gases Supply LAM490 users must confirm with etching module staffs that Cl2 gas are ready to use when you are going to do a polysilicon etch with chlorine gas. Copyright by Hong Kong University of Science & Technology. All rights reserved. Page 10

11 5.4.2 Wafer Alignment Preparation Use the flat align tool to align the flat position of wafers on the LOAD cassette. First, hold down the lever at the left side, then turn the knob until the flat aligned (Fig.7). Make sure an empty UNLOAD cassette has been placed on the designated slot of the exit load lock for receiving the etched wafers (Fig.8). If you have any problem about using the cassette and flat align tool, please consult NFF etching module. Fig.7 Flat align tool Fig. 8 Empty UNLOAD cassette located at the exit load lock chamber 6.0 Introduction to LAM490 operation system 6.1 Load and Edit recipe Load a Recipe Please make sure you load a right recipe, a wrong recipe may get unexpected results. Please read the following recipe loading procedures: Copyright by Hong Kong University of Science & Technology. All rights reserved. Page 11

12 1. Select right recipe cartridge. 2. Insert recipe cartridge into the port located under CRT display as shown (Fig. 9) 3. Click LOAD key to load the recipe stored in the cartridge (Fig. 9). 4. Click RECIPE key to access the Recipe page. Then view and confirm the details of the loaded recipe from the CRT display. All the recipe steps and details can be displayed in the recipe page by using the four arrow keys (Fig.9). 5. If the loaded recipe is correct, pull out the cartridge from the slot. Do not attempt to click SAVE key to change any parameters stored in the cartridge. Fig.9 Recipe loading keys and Recipe cartridge Edit a Recipe Please be reminded only Completion field, Etching step time, and Over-etch step time is allowed to be changed in the recipe page by user. However, it is strictly prohibited to change other parameters, including Pressure, RF power, Gap spacing, Gases flow rate, and other step time. In the Completion field, you can click the FIELD key to select different termination methods of a particular step. There are 5 selections are available: Time, Stability or Time, Time and Endpoint, Over-etch, and Recipe (Fig.10). Copyright by Hong Kong University of Science & Technology. All rights reserved. Page 12

13 Fig.10 Recipe details in the main screen Time: when Time field is selected, then step completes after a certain amount of time as specified in the Wait field. Stability or Time: when Stability or Time field is selected, then the recipe advances to the next step after all the desired parameters in the current step are reached. If stability is not achieved within the time limit specified in the Max field, the machine suspends processing until you reset the alarm on the Machine Parameters page or by activating the Manual Endpoint field on the Status page. When the alarm is cleared, the process continues to the next step without verifying that stability was ever achieved. Time and Endpoint: when Time and Endpoint field is selected, then the etching step terminates optically with the endpoint detector or after a certain period of time as specified in the Wait field. The endpoint setting parameters should be entered for that step on the Endpoint Parameters page describe in the following section. Over-etch: when Over-etch field is selected, it is associated with a percentage field. In etch step that RF is on, the duration of that step is timed. When an over-etch step executes, the time of over-etch is determined by that etch time multiplied by the specified percentage. Copyright by Hong Kong University of Science & Technology. All rights reserved. Page 13

14 Recipe: when Recipe field is selected, it signifies that the previous step is the last recipe step, and the recipe will be ended Edit endpoint parameters To access the Endpoint Parameters page, click the PARAMETERS key to the Machine Parameters page, then move the cursor to the top PARAMETERS: [MACHINE] field, and click FIELD SELECT key to switch to the PARAMETERS: [ENDPNT], then Endpoint Parameters page can be achieved (Fig.11) Fig.11 Endpoint setting page In Endpoint parameters page, there are few parameters can be edited: Sampling input, Active during recipe, Delay time before Normalizing, Normalize Time, and Endpoint Triggering %. A description of field parameters follows: Sampling Input: This field set the endpoint channels required to provide the endpoint algorithm for up to 4 etching steps in any recipe. Typically, Channel A will be used for endpoint detecting that employing Cl2 as the etching gas, and Channel B will be used for endpoint detecting that employing SF6 as the etching gas. Copyright by Hong Kong University of Science & Technology. All rights reserved. Page 14

15 Active During Recipe Step: This field specify the step number where the endpoint parameters will be active. Delay Time Before Normalizing: This field specify a time period for plasma stabilization prior to establishing a normalized value. Normalize Time: This field specify the duration of the signal sampling done to establish a normalized signal reference level. A sample signal is taken every 0.25s for the period of time selected. The average of the samples taken becomes the normalized value, representing 100% signal. Endpoint Triggering %: This field allows users to input a percentage of the normalized endpoint signal used for triggering the endpoint. The following table provides typical setting in Endpoint parameter page, user can use as reference. Si3N4 on SiO2 Poly-Si on SiO2 (SF6) Poly-Si on SiO2 (Cl2) Typical thickness >1000A >5000A >5000A Endpoint channel B only B only A only Analog I/P channel Step Delay 20s 20s 20s Normalize 10s 10s 10s Trigger 90% 95% 94% Signal 154 to to to 140 Table 1 Endpoint default setting Signal Options Page To observe the analog input signal readout from the endpoint detector, a signal options page must be accessed by clicking OPTIONS key. In this Options page, all the analog input readout will be shown at the bottom part of the display. Typically, channel 12 is used for monitoring the signal from endpoint detection channel A, and channel 13 is used for monitoring the signal from endpoint detection channel B (Fig.12). Copyright by Hong Kong University of Science & Technology. All rights reserved. Page 15

16 Fig.12 Analog Input signal 7.0 Auto Process Run The whole etching sequence involves, 1) Set Wafer Cassette, 2) Send and Load wafer, 3) Pump down and wafer loading, 4) Start Etching Process, 5) Unload Wafer, and 6) Return Wafer. 7.1 Set Wafer Cassette Set wafer cassette on the designated slot of the entrance load lock for sending wafer into the process chamber (Fig. 13). Fig.13 Set wafer cassette Copyright by Hong Kong University of Science & Technology. All rights reserved. Page 16

17 7.2 Send and Load wafer Once the wafer cassette is ready, then click the keyboard START key to start the wafer sending procedures and etching steps. Firstly, the send indexer loads a wafer from the send cassette onto the wafer belt drive system (Fig.14a). Then, the belt takes wafers to the entrance station lifter (Fig.14b). Finally, loadlock arm takes the wafer into the loadlock chamber (Fig.14c). However, user must pay attention to the wafer sending status; it may have chance the wafer is not sending out. If it happens, take out the wafer, put back to the load cassette, wafer align and start the process again. However, make sure do not start a process without wafer in the chamber; otherwise it will seriously damage the chamber s pin lifter. Fig.14a wafer send indexer Fig.14b belt drive wafer Fig.14c wafer loading 7.3 Pump down and wafer loading Once the loadlock arm returned, then outer door close and loadlock chamber will be evacuated. When the loadlock reaches a set crossover pressure, the inner door opens and the arm loads the wafer into the process chamber. 7.4 Run etching recipe When the wafer loaded into the electrode, then process recipe start to run, gases are introduced, and power is applied to the upper electrode. In order to check the status of the chamber, click the STATUS key to the chamber status page (Fig.15). In this page, step number, step time remaining, gas flow, RF forward and reflected power, gap spacing, electrode temperature, and all vacuum conditions can be obtained. Typically, the upper left hand corner displays the machine status and alarms. Once process starts, the recipe step number will display at the top of the Status page along with the time remaining for that particular step. Then, the gas system is represented by five boxes; each gas box is labeled with a gas name and displays the gas flow rate or set point. To display the set Copyright by Hong Kong University of Science & Technology. All rights reserved. Page 17

18 point or monitor the current flow rate, move the cursor to the SETPT/MON field in the Status page, and click keyboard FIELD SELECT key to toggle the field back and forth between set point (SETPT) or monitor (MON). At the center of the status display, it shows chamber pressure, RF power, electrode gap spacing, temperature, and bias. However, recipe set point values are only displayed for a recipe step in process. Fig.15 Chamber status page When the etching process starts, once the RF power successfully matched, then the plasma ignite, and the color of plasma can be observed through the view port at the rear part of the machine (Fig.16). The plasma color will be vary and depends on the etching gases and pressure used. Copyright by Hong Kong University of Science & Technology. All rights reserved. Page 18

19 Fig.16 Plasma ignition During the etching, a STOP key can be used to stop releasing any more wafers from the send cassette, and wafers previous sent will complete the remaining process cycles. However, to skip/terminate a recipe step, move the cursor to the MANUAL ENDPT field in the right middle of Status page, and click keyboard FIELD SELECT key to select ON. Then a recipe step will be skipped or terminated (Fig.15). After all the etching steps, a purge and pump down steps will be carry out to purge and pump out all the hazard gases used in the process. 7.5 Unload wafer After process, wafer will be unloading to the exit loadlock. Then, loadlock chamber will vent to atmosphere for further unloading to the exit belt drive system. 7.6 Return wafer Finally, the exit belt drive will send the wafer back to the cassette placed on the exit station. However, if you failed to place the receiver cassette, then the wafer transportation will be halted until it detected a receiver cassette. 7.7 Chamber clear In case, there is problem during running, and wafers need to be returned. Then, a Wafer Cleanout command can be used to do this. To do this, access the PARAMETERS: Copyright by Hong Kong University of Science & Technology. All rights reserved. Page 19

20 [MACHINE] page, click the main keyboard PARAMETERS key, then click FIELD SELECT key to switch between PARAMETERS: [MACHINE] field or PARAMETERS: [ENDPNT] field (Fig.17). In the page, click the Wafer Cleanout command to initiate the wafer clean out procedures automatically. When this command was used, then all the function keys will be disabled until the cleanout procedures complete. Fig. 17 Wafer clean out 8.0 Process Recording 1. Please be reminded you are required to fill all the details of the log sheets. If users fail to do this, a heavy punishment will be given. 2. Write down the problems happened or any comments in the log sheets. 9.0 Clean up 1. Clean up the area. 2. Return the cassettes to its original position. 3. Return alignment tool to their proper position Check out Check out the equipment immediately after use. Copyright by Hong Kong University of Science & Technology. All rights reserved. Page 20

21 Appendix Silicon Mark STEP PRESSURE (mt) T 0 0 RF TOP (w) GAP (cm) CL O He SF C2F COMPL Time Stable Endpoint Time Time Recipe TIME (s) Silicon Nitride/SiO2 STEP PRESSURE (mt) T 0 0 RF TOP (w) GAP (cm) CL O He SF C2F COMPL Time Stable Endpoint Over-etch Time Time Recipe TIME (s) 5 60s 10% Copyright by Hong Kong University of Science & Technology. All rights reserved. Page 21

22 Polysilicon (SF6)/SiO2 STEP PRESSURE (mt) T 0 0 RF TOP (w) GAP (cm) CL O He SF C2F COMPL Time Stable Endpoint Over-etch Time Time Recipe TIME (s) % Polysilicon (Cl2)/SiO2 STEP PRESSURE (mt) RF TOP (w) GAP (cm) CL O He SF C2F COMPL Time Stable Time Time Stable Endpt Overtime Time Time Time Recipe TIME (s) Copyright by Hong Kong University of Science & Technology. All rights reserved. Page 22