ThermcoNitride

Silicon nitride (or nitride or Si3N4) is deposited at moderately high temperatures (~800C) and low pressure (~250 mtorr), using dichlorosilane (SiCl2H2) and ammonia (NH3). This furnace handles wafer up to 6 inch.

Operating Procedure

Basic Operation Instructions

Check Tube Status

Press Do key until Main Menu is reached.
Use arrow keys to highlight Status Menu then press Return.
Use arrows keys to highlight Tube Status then press Return.
Type in Tube ID (4 for ThermcoNitride), then press Return.
System should be running STBYNIT; in prochold; temperature 525c

Vent Tube

Press START (STBYNITrecipe ends when boat is out)
Load your wafers.

Load Recipe

Enable Tube.
Press STOP button until tube is in standby.
Press Do key until Main Menu is reached.
Use arrow keys to highlight Recipe Menu then press Return.
Use arrows keys to highlight Compile Recipe then press Return.
Type in Recipe Name (N2, LSN, LSNTEST), then press Return.
For Recipe Name #2, press Return.
For Parameter Table, press Return.
Use arrow keys to highlight Download Only then press Return.
Type in Tube ID (4 for ThermcoNitride), then press Return.
Recipe parameter is time.
Type Delay Time (in the HH:MM:SS format) then press Return.

(Thermco will flash orange Recipe Compile Succeeded once recipe is loaded.)

Run Program

Press START to initiate recipe, after 10 seconds press START a second time to initiate the tube close.
Monitor and log the lowest base pressure, the highest leak back pressure and the pressure during deposition.
Wait for tube to process wafers. After deposition, the tube will ramp down to 525c and hold until you press START. The tube will vent and open (~17 min).
Unload your wafers after they have cooled several minutes.
Press STOP button until tube is in standby.
Compile the STBYNIT recipe.
Press START to initiate tube close.
STBYNIT will leakcheck tube and the stop in the process hold steo.
Disable tube.
Mute tube.

If Leak Check Fails

Put tube in standby.
Compile NITYOUT recipe.
Press START. The recipe will reset temperature, backfill and then boat out.

Process Monitoring and Machine Qualification

Each month, tool qualification runs are performed on most tools in the SNF to monitor variations in each tool’s performance. The purpose of the ThermcoNitride qual is to monitor Nitride thickness and uniformity both wafer-to-wafer and within-a-wafer. The qual is performed by SUMO members, but users may perform the specified qual process before tool use if more recent qual data is desired for reference.

For more information on the SNF tool performance monitoring system and SUMO, please see the Monthly Tool Monitoring page under the Equipment tab on the SNF wiki.

Qual Process Overview

The ThermcoNitride qual consists of two tests, each of which must be performed once per month. The first runs four wafers through the LSNTEST program for 1:15:00. The second runs four wafers through the Nitride2 program for 00:30:00. After the deposition, the wafers are analyzed via the STS PECVD Nitride Qual.

Procedure

Wafers for Processing

SUMO Wafer # (all Si 4" wafers)	Test	Location
23	N2	B1-23
24	N2	B1-24
25	N2	B2-2
26	N2	B2-3
27	LSNTEST	B1-23
28	LSNTEST	B1-24
29	LSNTEST	B2-2
30	LSNTEST	B2-3

LSNTEST Qual (First Week of Each Month):

Use four new 'L' test wafers; <100>, P-type (boron), 10-20 ohm-cm.
Clean at wb-clean1/2 in the following sequence; 5:1:1 DI:H2O2:NH4OH ten minutes, rinse, 5:1:1 DI;HCl:H2O2 ten minutes, rinse, 50:1 DI:HF 30 sec, rinse, spin dry.
Load program LSNTEST into Thermconitride furnace. Time variable is 01:15:00.
Load wafers into boats using clean (non-teflon) tweezers or vacuum wand. Load wafers with the major flat up into the boats in the following positions:

1^st boat: (Front closest to tube door), 20 empty slots,
1^st two dummies, (slots 21 & 22)
1^st boat: two test wafers (slot 23 & 24),
1^st boat: one dummy. (slot 25)
2nd boat: one dummy, (slot 1)
2nd boat: two test wafers (slot 2 &3),
2nd boat one dummy, 21 empty slots.

LPCVD Test wafers

Nitride2 Qual (Third Week of Each Month)

Use four new 'L' test wafers; <100>, P-type (boron), 10-20 ohm-cm.
Clean at wb-clean1/2 in the following sequence; 5:1:1 DI:H2O2:NH4OH ten minutes, rinse, 5:1:1 DI;HCl:H2O2 ten minutes, rinse, 50:1 DI:HF 30 sec, rinse, spin dry.
Load program nitride2 into Thermconitride furnace. Time variable is 00:30:00.
Load wafers into boats using very clean (non-teflon) tweezers or vacuum wand. Load wafers with the major flat up into the boats in the same positions as described in the above procedure for the LSNTEST qualification run.

Post-Deposition Measurements

Measure the thickness and index of refraction at 9 points across the wafer using STS PECVD Nitride Qual
Report the average thickness, standard deviation, and n at 633 nm for the wafer. Test sites should be no more than about 15mm from the edge of the wafer.

Reported Data

Qual data may also be found on the Badger comment log. The following data is reported for the ThermcoNitride qual.

average deposition thickness
one standard deviation
index of refraction

Expected deposition thickness (LSNTEST): 6500 A

Expected deposition thickness (N2): 900 A

If test values are not within 10% of plotted test average, contact the Diffusion Process/Maintenance team. Save wafers in a box with the date, furnace number, program name and growth time. They may be re-tested sometime in the future.

Qualification Results

LSNTEST Results

Nitride2 Results

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