Database Infrastructure with Smart Software Layer For Semiconductor Manufacturing David Q. Kelly, Ph.D.

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1 Database Infrastructure with Smart Software Layer For Semiconductor Manufacturing David Q. Kelly, Ph.D. VCSEL Product Engineering, Finisar Corporation

2 Vertical Cavity Surface-Emitting Laser (VCSEL) Product Portfolio Single Mode High Speed High Power Small die 150mm x 150mm Polarization controlled 850, 894nm >1mW optical power Custom wavelengths >28Gbps Multiple wavelengths Operation to >85C TT1%Fail > 10 years 1xN arrays Custom layouts CW Power > 10W Peak Power > 100W 850 and 940nm

3 New Growth Area for High-Power VCSELs for 3D Sensing Finisar's short-wave vertical cavity surface-emitting laser (VCSEL) technology was acquired from Honeywell in 2004 GaAs wafer fab located in Allen, TX, USA supplies VCSELs for use in optical transceivers New growth area is high-power VCSEL arrays for consumer, automotive, and commercial 3D sensing applications Typical VCSEL array chip size is 1-2 mm 2 VCSEL array chip can have hundreds of laser emitters Optical characteristics of each laser emitter must be measured Massive data storage requirements!

4 Motivation Data infrastructure needed overhaul to support growing VCSEL market Existing IT and software ecosystem relies heavily on Microsoft technologies: Microsoft SQL Server databases for data storage and recall operations Micosoft.NET Framework for test software development Finisar's legacy data infrastracture was overly complex and cumbersome Database tables that were originally developed for engineering use evolved into production tables Database tables were linked to one another by "lookup values" rather than strict primary key / foreign key relationships Wafer test data stored in a legacy file format which could only be interpreted by legacy software Inadequate data validation

5 Overview Given that Finisar's IT ecosystem already relied heavily on Microsoft technologies, the desire was to invent a new data infrastructure that achieved the following objectives: Data should be stored in a Microsoft SQL Server database Data must be validated before storing in the database Large amounts of raw data should be stored without sacrificing speed of read/write operations Database should be relational and all tables should make use of strictly-enforced primary key / foreign key relationships Finisar has developed a relational database infrastracture and a supporting "smart" software layer for all read/write operations

6 Relational Database Design Primary Key Foreign Key WAFER_KEY WAFER_NUMBER PRODUCT_KEY SCRIBE_ID AA AB DE WAFER Table Primary Key PRODUCT_KEY PRODUCT WAFER_DIAMETER DIE_SIZE_X DIE_SIZE_Y 1 VCSEL_ VCSEL_ VCSEL_ PRODUCT Table The primary keys of each table should be surrogate data values that represent the actual data

7 Binary Large Objects (BLOBs) Products with small die sizes can have up to 250k dies per wafer, with a dozen or more test values per die Millions of test values per wafer Row count would be unmanageable if every test value stored in a separate row in the database Row count still unmanageable even if all test values for a single die are stored in one row If a Binary Large Object (BLOB) is used to store the data, then all of the test values for all of the dies on the wafer can be stored in a single database row With Microsoft SQL Server, the data type for the column is varbinary(max) With a suitable compression scheme, all numbers can be stored using 2 bytes for each number Byte array organized as follows, where n is the number of tests, and m is the number of dies: b 0,0 [0] b 0,0 [1] b 0,n [0] b 0,n [1] b 1,0 [0] b 1,0 [1] b m,n [0] b m,n [1]

8 Wafer Probe Record Example PROBE_RECORD_KEY WAFER_KEY TEMPERATURE START_TIME STOP_TIME TESTER_KEY /1/17 1:00 AM 10/1/17 3:10 AM /1/17 2:30 AM 10/1/17 4:30 AM /2/17 4:15 PM 10/2/17 7:45 PM 6 PROBE_RECORD Table PROBE_RECORD_KEY DATA_BLOB 1 0x018F9C 2 0x1A4B6E 3 0x2FFF3A PROBE_DATA Table Main probe record table contains information about the probe data (wafer, temperature, start/stop time, tester, etc.) BLOB data is stored in a separate table, linked using a primary key BLOB columns contains all of the data for every die on the wafer

9 Data that can be stored as a BLOB Wafer probe raw data Wafer map information that instructs probers on which dies to probe Bin maps for die sorters Wafer acceptance or burn-in data Possibilities are endless Be careful not to overuse the BLOB, however: BLOB data requires a software layer to interpret the data If the BLOB is overused, it puts unnecessary barriers between the data and the data consumers

10 "Smart" Software Layer Since the information in a BLOB is stored as raw bytes, a software layer is required to "unwrap" the data and make it presentable to data consumers The "smart" software layer comes in two incarnations:.net class library (DLL) that can be used in test software, data visualization, data exporting tools, etc. Assemblies deployed to the server that contain user-defined CLR functions and stored procedures Microsoft documentation on CLR User-Defined Functions

11 SQL Query that returns the raw probe data for wafer measured at 50C: PROBE_RECORD_KEY WAFER_KEY TEMPERATURE START_TIME STOP_TIME TESTER_KEY /1/17 1:00 AM 10/1/17 3:10 AM /1/17 2:30 AM 10/1/17 4:30 AM /2/17 4:15 PM 10/2/17 7:45 PM 6 PROBE_RECORD Table PROBE_RECORD_KEY DATA_BLOB 1 0x018F9C 2 0x1A4B6E 3 0x2FFF3A PROBE_DATA Table WAFER_KEY WAFER_NUMBER PRODUCT_KEY SCRIBE_ID AA AB DE WAFER Table SELECT DATA_BLOB FROM PROBE_DATA WHERE PROBE_RECORD_KEY = (SELECT PROBE_RECORD_KEY FROM PROBE_RECORD WHERE WAFER_KEY = (SELECT WAFER_KEY FROM WAFER WHERE WAFER_NUMBER = ' ') AND TEMPERATURE = 50); Returns 0x2FFF3A Useless array of bytes as is Requires "unwrapping"

12 CLR function called "Get_PROBE_DATA_By_Temperature" deployed to the server from an assembly: SELECT * FROM Get_PROBE_DATA_By_Temperature(' ', 50) CLR function interprets the BLOB data, pulls the wafer map, pulls the test list, etc. PROBE_RECORD_KEY WAFER_NUMBER DIE_X DIE_Y TEST_NAME TEST_VALUE UNITS BIN_CODE Voltage1 0.1 V Voltage2 0.2 V Current1 0.4 A Current A Power W Power W Voltage V Voltage V Current A Current A Power W Power W 1 Data stored as BLOB, but output of query is human-readable!

13 "Smart" Software Layer Data Validation Example Scenario: Test software utilizing the "smart" software layer's class library (DLL) stores results locally while probing the wafer When wafer prober completes the wafer, the class library is used by the test software to push the results to the database Class library confirms that all dies in the wafer map are present in the results before allowing the data to be written to the database If data is incomplete, the class library throws an exception Incomplete probe data

14 "Smart" Software Layer Triggers and Post-Processing Capabilities Example Scenario: There is a need to probe the wafers at multiple temperatures and under different conditions A wafer can be probed 3 or 4 times depending on the product requirements The "smart" software layer can utilize CLR stored procedures to combine all probe results into a single bin map, which is triggered when the final probe result for a wafer is written Multiple wafer probe data sets Database trigger

15 "Smart" Software Layer used by Third-Party Data Tools Data analysis tools require an interface to the internal database where the data is stored Vendors that create data tools can utilize the "smart" software layer to pull data and format it according to their requirements Finisar uses YieldWatchDog for data monitoring

16 Data Infrastructure Database Software Layer User Interface Test Software MES Database (Factory Control) Database.NET Software Web Portal YieldWatchDog Data Visualization Tools

17 One Database, One Software Layer A single database is used for all data storage Relationships between data are controlled using strict primary key / foreign key relationships All data must go through the software validation layer

18 Conclusion Growth in Finisar's VCSEL business has necessitated upgrades to our data infrastructure Microsoft SQL Server has been utilized to store large amounts of wafer data using binary large objects (BLOBs) Primary key / foreign key relationships using surrogate data have been used for linking records.net class library and user-defined CLR functions and stored procedures constitute a "smart" software layer that performs the following functions: Interpretation and "unwrapping" of BLOB data Data validation Calculations and post-processing triggered on data inserts Interface for third-party data tools