semi合集-English.pdf - 第7432页

SEMI MF1529-1104 © SEMI 2004 13 RELATED INFORMATION 1 SINGLE LAB TEST RESULTS NOTICE : This relat ed information is not an offi cial part of SEMI M F1529. It was derived fro m informat ion developed du ring the original …

SEMI MF1529-1104 © SEMI 2004 12

15.1.1 The wafers in these tests were fabricated by five

different processes. The purpose of these tests is to

demonstrate the consistency of determination of sheet

resistance uniformity with dual-configuration four-

probe measurements, not to determine the uniformity

achievable by a given process. The five processes

utilized are capable of both better and poorer uniformity

than seen here.

15.1.2 The repeatability of uniformity values given here

represent good measurement practice, but the

consistency of values for each wafer might have been

even better if all measurements had been taken over a

shorter time interval.

15.1.3 A standard deviation, (in percent), was used to

represent the uniformity values obtained for each test

on each of the wafers. While it is common to give

repeatability values as a standard deviation, in order to

avoid confusion from duplication of terminology, the

repeatability of the repeated determinations of non-

uniformity for each type wafer are given in Table R1-1

as the range of standard deviation values obtained in the

original tests.

15.1.4 A straightforward propagation of errors based on

the performance specifications, in order to estimate the

precision, does not appear possible. Required

instrument resolution, power supply stability, and probe

performance qualification are designed to allow a

relative accuracy and precision of better than 0.1% for

all measurement sites on a wafer. However, for wafers

with high uniformity (for example, standard deviation

of all measurement site values on the order of 0.2%),

even these requirements may not ensure good two-

party, or multilaboratory agreement on the wafer

uniformity.

15.2 Bias — A statement of bias cannot be made

because there are no semiconductor reference artifacts

with a known level of non-uniformity.

16 Keywords

16.1 epitaxy; four-point probe; ion implant;

metallization; polysilicon; sheet resistance; silicon

SEMI MF1529-1104 © SEMI 2004 13

RELATED INFORMATION 1

SINGLE LAB TEST RESULTS

NOTICE: This related information is not an official part of SEMI MF1529. It was derived from information

developed during the original preparation of the standard in ASTM Committee F-1 in 1994. This related

information was approved for publication by full letter ballot procedures on August 16, 2004.

R1-1 One wafer from each of five different thin film

types was tested for uniformity. Each was 100 mm

diameter. A measurement test-site plan using 81 test

locations located at wafer center and on four equally

spaced circles with a maximum radius of 38.1 mm, as

described in SEMI MF1618, was used for all

measurements. The measure of uniformity for

measurements on each wafer was the standard deviation

of the 81 measured values expressed as a percent of the

mean measured value. For each of the wafers, 11 to 13

tests of uniformity were run over periods that ran from

3 to 6 months, depending on the individual wafer.

R1-1.1 Temperatures of the wafer stage were

monitored and recorded. Average sheet resistances

were found to change as a function of temperature but

no corresponding corrections of sheet resistance values

were made because the temperature coefficients of

resistivity were not known for the films involved. The

assumption was made that the determination of

uniformity should be minimally affected as long as the

temperature stayed relatively constant during the course

of each measurement run.

R1-1.2 Results of this test are summarized in Table

R1-1. The highest temperatures used for each wafer

were achieved by deliberate elevation of room

temperature in order to determine whether temperature

affected average sheet resistance or uniformity value.

Temperature dependence of average sheet resistance

was seen for wafer Types 1, 2 and 5. No dependence of

sheet resistance uniformity on temperature was seen.

R1-2 An additional test involved three measurements

of uniformity on each of three different wafers from the

same five thin-film fabrication processes. These tests

were completed within three days. They were also

associated with evaluation of the repeatability

capability of the sheet resistance measurement

instrumentation. For this evaluation of the instrument,

50 measurements were made on each wafer by taking

10 very closely spaced measurements in each of five

relatively widely separated locations on the wafer. The

assumption was made that in each group of ten, the

measurements were so closely spaced compared to the

sampling volume of the four-point probe that any

variability experienced was a measure of the equipment

repeatability (imprecision) and was not caused by

variations in the thin film itself. The actual

measurements of wafer uniformity used the same 81-

point test pattern as used for the wafers in Section R1-1

R1-2.1 The measurements from this test, summarized

in Table R1-2, show that for each process, the three

wafers have a different average sheet resistance, even

when measured at the same nominal temperature and

they also have rather different levels of non-uniformity

as determined from the standard deviations of the 81

measurements. The variation of these run-to-run

standard deviations for a given wafer is seen to be small

compared to the typical wafer-to-wafer standard

deviations for the different wafers from a given process.

Table R1-1 Summary of Sheet Resistance Uniformity Tests Made by Dual-Configuration Four-Point Probe

Measurements at One Laboratory on One Wafer from Each of Five Thin Film Fabrication Processes

Process

Nominal

Resistance,



Number of Test

Runs

Range of

Temperatures, °C

Range of Mean

Values,



Range of

Uniformity Values,

(1) Boron Implant

1.3 × 10

/60 keV

570 13 19.35–28.45 566.3–574.6 1.83–1.89

(2) Phosphorus Implant

5 × 10

/100 keV

144 13 20.21–27.73 143.4–144.4 0.81–0.86

(3) Arsenic Implant

5 × 10

/60 keV

26 13 20.94–32.48 26.33–26.78 0.67–0.69

(4) Polysilicon

600-nm thickness

900° deposition temperature

14.5 11 21.41–26.00 14.48–14.55 0.24–0.24

(5) n/p-epitaxy 3 m/1.2  cm

4,000 11 20.23–30.92 4021–4301 1.53–1.62

Measurements were not corrected for changes in temperature.

Table R1-2 Uniformity Results from 3 Runs on 3 Waters Each from 5 Different Processes

Process Instrument Precision Wafer Parameter

Run 1 Run 2 Run 3

Boron Implant 0.028% Average Resistance 534.8  531.8  534.1 

Wafer 4 Standard Deviation 0.69 % 0.68 % 0.74 %

Temperature Range 26.0–26.2°C 19.4–20.1°C 23.4–23.9°C

Boron Implant 0.028% Average Resistance 556.4  553.8  554.7 

Wafer 5 Standard Deviation 1.23 % 1.22 % 1.23 %

Temperature Range 25.6–25.9°C 20.4–21.1°C 24.2–24.7°C

Boron Implant 0.028% Average Resistance 550.7  547.8  549.7 

Wafer 6 Standard Deviation 1.35 % 1.34 % 1.33 %

Temperature Range 25.6–26.0°C 21.0–21.6°C 24.6–25.0°C

Phos. Implant 0.18% Average Resistance 147.5  148.1  147.5 

Wafer 4 Standard Deviation 0.71 % 0.71 % 0.69 %

Temperature Range 20.4–21.0°C 24.9–25.2°C 20.5–21.2°C

Phos. Implant 0.018% Average Resistance 149.4  149.7  149.2 

Wafer 5 Standard Deviation 0.81 % 0.81 % 0.82 %

Temperature Range 21.4–21.9°C 24.9–25.2°C 21.6–22.3°C

Phos. Implant 0.018 Average Resistance 145.9  146.0  146.0 

Wafer 6 Standard Deviation 1.45 % 1.45 % 1.45 %

Temperature Range 22.4–22.8°C 22.1–22.7°C 22.4–22.9°C

Arsenic Implant 0.012% Average Resistance 26.16  26.16  26.16 

Wafer 4 Standard Deviation 0.57 % 0.56 % 0.56 %

Temperature Range 22.7–23.2°C 21.5–22.0°C 22.8–23.4°C

Arsenic Implant 0.012% Average Resistance 25.06  24.88  24.93 

Wafer 5 Standard Deviation 0.77 % 0.77 % 0.77 %

Temperature Range 22.0–27.0°C 22.2–22.7°C 23.4–24.0°C

Arsenic Implant 0.012% Average Resistance 27.55  27.34  27.44 

Wafer 6 Standard Deviation 0.74 % 0.74 % 0.74 %

Temperature Range 26.6–26.7°C 22.8–23.3°C 263.9–24.5°C

Polysilicon 0.009% Average Resistance 15.88  15.86  15.84 

Wafer 4 Standard Deviation 0.59 % 0.58 % 0.59 %

Temperature Range 24.2–24.7°C 23.0–23.5°C 22.1–22.6°C

Polysilicon 0.009% Average Resistance 14.69  14.72  14.69 

Wafer 5 Standard Deviation 0.29 % 0.29 % 0.29 %

Temperature Range 24.6–25.0°C 23.5–24.0°C 22.1–22.6°C

Polysilicon 0.009% Average Resistance 16.97  16.96  16.93 

Wafer 6 Standard Deviation 0.32 % 0.31 % 0.32 %

Temperature Range 24.9–25.3°C 23.8–24.3°C 22.2–22.7°C

n/p-epitaxy 0.08% Average Resistance 3982  3933  3961 

Wafer 4 Standard Deviation 0.89 % 0.73 % 0.69 %

Temperature Range 23.6–23.7°C 20.4–21.0°C 21.4–22.0°C

n/p-epitaxy 0.08% Average Resistance 3857  3800  3805 

Wafer 5 Standard Deviation 1.58 % 1.60 % 1.56 %

Temperature Range 23.6–24.0°C 21.5–22.1°C 21.4–22.0°C

n/p-epitaxy 0.08% Averager Resistance 3929  4006  3940 

Wafer 6 Standard Deviation 1.66 % 1.75 % 1.67 %

Temperature Range 19.5–20.0°C 22.4–22.9°C 20.7–21.3°C

The temperature range given is variation within each individual measurement run of 81 test sites. In Table R1-1 the temperature range given is the variation of the

average temperature for each of the test runs.