A111D3 0fl7SQb

NATL INST OF STANDARDS & TECH R.. .C.

A1 11 03087506

Thurber, W. Robert/Microelectronic test QC100 .U57 NO.400-, 32, 1978 C.2 NBS-PUB /

»6AU Of

NBS SPECIAL PUBLICATION 400-32

U.S. DEPARTMENT OF COMMERCE / National Bureau of Standards

Semiconductor Measurement Technology:

Test Pattern NBS-4
NATIONAL BUREAU OF STANDARDS

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a Located at Boulder, Colorado 80302.
Semiconductor Measurement Technology

Microelectronic Test Pattern NBS-4

H78 jrnu ft St**!**

W. Robert Thurber and

Martin G. Buehler

Electronic Technology Division

Institute for Applied Technology

National Bureau of Standards

Washington. D.C. 20234

This activity was supported by The Defense Advanced Research Projects Agency

and The National Bureau of Standards

U.S. DEPARTMENT OF COMMERCE, Juanita M. Kreps, Secretary

Dr. Sidney Harman, Under Secretary

Jordan J. Baruch, Assistant Secretary for Science and Technology

NATIONAL BUREAU OF STANDARDS. Ernest Ambler. Director

Issued April 1978
Library of Congress Catalog Card Number: 78-606024

National Bureau of Standards Special Publication 400-32

Nat. Bur. Stand. (U.S.), Spec. Publ. 400-32, 66 pages (Apr. 1978) CODEN: XNBSAV

U.S. GOVERNMENT PRINTING OFFICE

WASHINGTON: 1978

For sale by the Superintendent of Documents, U.S. Government Printing Office, Washington, D.C. 20402

Stock No. 003-003-01906-2, Price $2.75

(Add 25 percent additional for other than U.S. mailing).
CONTENTS

Page

Introduction 1 Test Structures 5 Resistors 6

3.1 Base Sheet Resistor (Greek Cross), Structure 4.22 6

3.2 Base Sheet Resistor (Greek Cross), Structure 4.24 6

3.3 Base Sheet Resistor (Greek Cross), Structure 4.25 6

3.4 Base Sheet Resistor (Offset Quadrate Cross), Structure 4.26 . . 6

3.5 Base Sheet Resistor (VDP , FP , CS), Structure 4.11 7

3.6 Incremental Base Sheet Resistor (VDP), Structure 4.35 8

3.7 Base Sheet Resistor (Bridge), Structure 4.33 9

3.8 Base Sheet Resistor (Bridge), Structure 4.23 9

3.9 Base-under-Emitter Sheet Resistor (Greek Cross),

Structure 4.20 9

3.10 Base-Contact Sheet Resistor (Greek Cross), Structure 4.21 ... 10

3.11 Emitter Sheet Resistor (Offset Quadrate Cross),

Structure 4.28 10

3.12 Emitter Sheet Resistor (Bridge), Structure 4.32 10

3.13 Metal Sheet Resistor (Greek Cross), Structure 4.19 11

3.14 Metal-to-Base Contact Resistor, Structure 4.29 11

3.15 Metal-to-Emitter Contact Resistor, Structure 4.27 . 11

3.16 Collector Four-Probe Resistors, Structures 4.1, 4.5, 4.7,

4.9, and 4.17 12

3.17 Collector Hall Effect Device (VDP), Structure 4.31 ...... 13

3.18 Metal Step-Coverage Resistor, Structure 4.38 13

3.19 Collector Spreading Resistor, Structure 4.18 14

MOS Capacitors 15

4.1 MOS Capacitor over Collector (Base DGR, CS) , Structure 4.2 . . 15

4.2 MOS Capacitor over Collector (Emitter DGR), Structure 4.3 . . 16

4.3 MOS Capacitor over Collector (FP, CS), Structure 4.8 17

4.4 MOS Capacitor over Collector, Structure 4.30 17

4.5 MOS Capacitor over Base, Structure 4.12 18

iii
Page

5. Diodes 19

5.1 Base-Collector Diode (FP, CS) , Structure 4.10 19

5.2 Base-Collector Diode (FP, CS) , Structure 4.14 20

6. Transistors 20

6.1 Bipolar Transistor, Structure 4.13 .... 20

6.2 MOS Transistor (Circular), Structure 4.15 21

6.3 MOS Transistor, Structure 4.16 22

7. Miscellaneous 2 3 7.1 Alignment Markers for Negative Photoresist, Structure 4.4 N . .23

7.2 Alignment Markers for Positive Photoresist, Structure 4.4 P . .24

7.3 NBS Logo, Structure 4.6 24

7.4 Surface Profilometer Structure, Structure 4.34 25

7.5 Etch-Control Structures, Structures 4.36 B, E, C, M, BC , G . . 26

7.6 Resolution Structures, Structures 4.37 B, E, C, M, BC , G ... 26

References 27

Appendix 28

LIST OF FIGURES

1. Test pattern NBS-4 fabricated with BASE (B) , EMITTER (E) , BASECONTACT (BC) , CONTACT (C) , and METAL (M) masks 3

2. An illustration of the notation used in views of a test structure . 5

3. Quadrant 1 of test pattern NBS-4 29

4. BASE mask for quadrant 1 of test pattern NBS-4 31

5. BASE-CONTACT mask for quadrant 1 of test pattern NBS-4 33

6. EMITTER mask for quadrant 1 of test pattern NBS-4 35

7. GATE mask for quadrant 1 of test pattern NBS-4 37

8. CONTACT mask for quadrant 1 of test pattern NBS-4 39

9. METAL mask for quadrant 1 of test pattern NBS-4 41

10. Quadrant 2 of test pattern NBS-4 43

11. BASE mask for quadrant 2 of test pattern NBS-4 45

12. BASE-CONTACT mask for quadrant 2 of test pattern NBS-4 . ." 47

13. EMITTER mask for quadrant 2 of test pattern NBS-4 49

iv
Page

14. GATE mask for quadrant 2 of test pattern NBS-4 51

15. CONTACT mask for quadrant 2 of test pattern NBS-4 53

16. METAL mask for quadrant 2 of test pattern NBS-4 55

17. Quadrant 3 of test pattern NBS-4 57

18. BASE mask for quadrant 3 of test pattern NBS-4 59

19. BASE-CONTACT mask for quadrant 3 of test pattern NBS-4 61

20. EMITTER mask for quadrant 3 of test pattern NBS-4 63

21. GATE mask for quadrant 3 of test pattern NBS-4 65

22. CONTACT mask for quadrant 3 of test pattern NBS-4 67

23. METAL mask for quadrant 3 of test pattern NBS-4 69

24. Quadrant 4 of test pattern NBS-4 71

25. BASE mask for quadrant 4 of test pattern NBS-4 73

26. BASE-CONTACT mask for quadrant 4 of test pattern NBS-4 75

27. EMITTER mask for quadrant 4 of test pattern NBS-4 77

28. GATE mask for quadrant 4 of test pattern NBS-4 79

29. CONTACT mask for quadrant 4 of test pattern NBS-4 81

30. METAL mask for quadrant 4 of test pattern NBS-4 83

LIST OF TABLES

1. Planar Test Structures on Test Pattern NBS-4 2

2. Test Structures Shown in Figures 3-9 28

3. Test Structures Shown in Figures 10-16 42

4. Test Structure Shown in Figures 17-23 56

5. Test Structures Shown in Figures 24-30 70

v
PREFACE

The work was conducted as part of the Semiconductor Technology Program at

the National Bureau of Standards. Portions of this work were supported by

the Defense Advanced Research Projects Agency (Order No. 2 397) and the NBS

.

In the semiconductor industry it is common practice to design photomasks in

English units. The photomasks used in this study were laid out in English

units. The equivalent metric unit is given in parentheses; in some cases the

equivalent is rounded off to an appropriate number of significant figures.

The authors wish to thank several members of the Electronic Technology Division for their assistance. Y. M. Liu developed the wafer fabrication processes, W. A. Cullins prepared most of the drawings, Cindy Cannon photographed the wafers and masks, and Jane Walters typed the manuscript.

vi
MICROELECTRONIC TEST PATTERN NBS-4

by

W. Robert Thurber and Martin G. Buehler

Abstract: Microelectronic test pattern NBS-4 is a re- vision of test pattern NBS-3 which was designed primarily for

evaluation of the resistivity-dopant density relationship in

silicon. Major changes include the addition of optional BASECONTACT and GATE masks and the incorporation of several new structures, some useful for the resistivity-dopant density

work, and others, mostly sheet resistors, included for evaluation of new designs.

The NBS-4 pattern contains 38 test structures such as planar

four-probe resistors, sheet resistors, MOS capacitors, p-n

junctions, bipolar and MOS transistors, Hall effect device,

and process control structures. The overall pattern is a square 200 mil (5.08 mm) on a side and is divided into four

quadrants which are separated by scribe lines. A detailed

layout of each structure is presented including both a top

view and a cross sectional view. Photomicrographs of each

quadrant and the quadrants of the six masks used in the fabrication of the pattern are shown in an appendix.

Key Words: Dopant density; microelectronics; MOS

capacitors; n-p-n transistor fabrication; p-n junctions;

resistivity; semiconductor electronics; sheet resistors;

silicon; test pattern; test structures.

1. INTRODUCTION

The purpose of this report is to describe the microelectronic test structures

found on test pattern NBS-4. This is accomplished primarily by drawings of

the structures, supplemented by photomicrographs of the masks and fabricated

wafers. Test pattern NBS-4 is a revision of test pattern NBS-3 [1] which was designed for study of the resistivity-dopant density relationship in silicon.

Significant changes include the addition of optional BASE-CONTACT and GATE

masks and the incorporation of new structures for the resistivity-dopant density work and for the measurement of sheet resistance. The pattern is com- posed of an array of 38 test structures, such as planar four-probe resistors,

sheet resistors, MOS capacitors, p-n junctions, bipolar and MOS transistors,

Hall effect device, and process control structures, which for the most part

are adaptations of commonly used configurations. Table 1 gives a list of

the test structures, their purpose, and one or more references with details

on their use. A majority of the structures are the same, or very similar, to ones on test pattern NBS-3, and the publication [1] on that pattern includes

discussion of each structure, equations for calculation of the quantities

determined by each, and additional references.

The devices specifically designed for the resistivity-dopant density evaluation are indicated by an asterisk in table 1. The square array four-probe

resistor [2] has proven to be the best structure for resistivity measurements,

and four structures of the same basic design, differing only in the size of

the collector pipes, were added as part of NBS-4. Two new MOS capacitor

structures were added for dopant density measurements. These devices are designed for steady-state, deep-depletion, capacitance-voltage measurements.

Bulk dopant density values can be obtained from the following structures:

MOS capacitors (4.2, 4.3, and 4.8), base-collector diode (4.10), MOSFET

1
Table 1 - Planar Test Structures on Test Pattern NBS-4

Page Number Test Structure3 Purpose References

12 4 .1 *Collector resistor (pipes 0.20 mil on Resistivity 1,2

a side)

15 4 .2 *MOS capacitor over collector (base DGR) Dopant density 4 16 4 . 3 *MOS capacitor over collector (emitter Dopant density 4 DGR)

23,24 4 .4 Alignment markers Mask alignment

12 4 . 5 Collector resistor (pipes 0.30 mil on Resistivity 1,2

a side)

24 4 .6 Logo Identification

12 4 .7 Collector resistor (pipes 0.40 mil on Resistivity 1,2

a side)

17 4 . 8 *MOS capacitor over collector (FP, CS) Dopan t den s i ty

,

Vf

, b

1,5

12 4 .9 *Collector resistor (pipes 0.50 mil on

tD Resistivity 1,2

a side)

19 4 .10 *Base-collector diode (FP, CS) Dopant density 1,6

7 4 .11 Base sheet resistor (VDP, FP , CS) Sheet resistance 1,3

18 4 .12 MOS capacitor over base Surface dopant 1 density

20 4 .13 Bipolar transistor Proper fabrication 1,7

20 4 .14 Base-collector diode (FP, CS) Dopant density 1,8

21 4 .15 *MOSFET (circular, W/L = 18.2) Dopant density 1,9

22 4 .16 MOSFET (rectangular, W/L = 4) Proper fabrication 1 12 4 .17 *Collector resistor (pipes 0.25 mil on Resistivity 1,2

a side)

14 4 .18 Collector spreading resistor Back-side resis- 1,10

tance

11 4 .19 Metal sheet resistor (Greek cross) Sheet resistance 1

9 4 . 20 Base-under-emitter sheet resistor Sheet resistance 7,11

(Greek cross)

10 4 .21 Base-contact sheet resistor (Greek Sheet resistance 12 cross)

6 4 .22 Base sheet resistor (narrow Greek Sheet resistance 3,12

cross)

9 4 .23 Base sheet resistor (B, W/L = 0.25) Sheet resistance 7,13

6 4 .24 Base sheet resistor (Greek cross) Sheet resistance 2 ,12

6 4 .25 Base sheet resistor (Greek cross, tab Sheet resistance 2,12

contacts)

6 4 .26 Base sheet resistor (offset quadrate Sheet resistance 2,12

cross)

11 4 .27 Metal-to-emitter contact resistor Contact resistance 1 10 4 .28 Emitter sheet resistor (offset quadrate Sheet resistance 1, 12 cross

)

11 4 29 Metal-to-base contact resistor Contact resistance 1 17 4 .30 MOS capacitor over collector (square) Measurement limita- 1 tions

13 4 31 *Hall effect device (VDP) Carrier density 1,14

10 4 . 32 Emitter sheet resistor (B, W/L = 0.25) Sheet resistance 1

9 4 .33 Base sheet resistor (B, W/L = 0.25) Sheet resistance 1,13

25 4 34 Surface profilometer structure Process control 1

8 4 35 Incremental base sheet resistor (VDP) Dopant profile 1,3

26 4 .36 Etch-control structures0 Process control 1 26 4 .37 Resolution structures0 Process control 1 13 4 . 38 Metal step-coverage resistor Metal continuity 1

* = structures designed for resistivity-dopant density evaluation.

B = bridge; CS = channel stop; DGR = diffused guard ring; FP = field plate; L = length

along current path; VDP = van der Pauw; W = width of current path.

^Vfk = flat band voltage.

CB = BASE mask; BC = BASE-CONTACT mask; C = CONTACT mask; E = EMITTER mask; G = GATE

mask; M = METAL mask.

2
Figure 1. Test pattern NBS-4 fabricated with BASE (B) , EMITTER (E) , BASECONTACT (BC) , CONTACT (C) , and METAL (M) masks. The length of the pattern

j along one side is 200 mil (5.08 mm).

3
(4.15), and Hall effect device (4.31). Bulk resistivity values can be found

from the square array four-probe collector resistors (4.1, 4.5, 4.7, 4.9, and

4.17) and the Hall effect device (4.31). It should be noted that the collector Hall effect device (4.31) is functional only after it has been scribed

from the wafer and the back-side metal removed. To accommodate this structure, the scribe grid was omitted from the BASE and EMITTER masks and included on only the CONTACT and GATE masks.

The new pattern also contains eight base sheet resistors, four of which were

not included on test pattern NBS-3. Comparative measurements have been made

on the six van der Pauw base sheet resistors [3]. The base-under-emitter

sheet resistor (4.20) is a new structure on the pattern. The metal sheet re- sistor (4.19) is of somewhat different design than that on test pattern NBS-3

to avoid the problem of burnout due to high current density in narrow connect

ing arms. The incremental base sheet resistor (4.35) was modified slightly

from the one on test pattern NBS-3. The width of the arms near the body was increased to minimize arm resistance which is especially important as the

structure is thinned by repeated layer removal. The addition of the basecontact diffusion in the arms further reduces the resistance. Also, the metal contact pads were enlarged to allow multiple wire bonds. Many of the re- maining test structures are in support of the primary devices. They were included to provide tests which can assure that proper fabrication steps have

been followed and aid in diagnosing problems.

A photomicrograph of test pattern NBS-4 is shown in figure 1. The overall

pattern is 200 mils (5.08 mm) on a side and is divided into four quadrants.

Enlarged views of each quadrant of the fabricated test pattern and the six

masks are shown in the Appendix. The masks are: BASE, BASE-CONTACT, EMITTER

GATE, CONTACT, and METAL. The BASE and BASE-CONTACT masks delineate regions

to be diffused with a conductivity type opposite from the collector substrate

and the EMITTER mask delineates regions to be diffused with a conductivity

type the same as the collector substrate. Emitter-diffused regions are more heavily doped than the collector. The BASE-CONTACT mask is designed to delineate heavily doped diffused regions where electrical contacts are made to

base-diffused regions. It is intended for use in the processing of p-type

wafers where low resistance contacts to n-type base regions are a problem.

With respect to the placement of the alignment markers, the base-contact diffusion was designed to follow the base diffusion. However, the diffusions do

not have to be done in this order and in the processing sequence used for the

resistivity-dopant density study the base-contact diffusion was made following the emitter diffusion so that the surface dopant density of the basecontact regions was not reduced by any subsequent high-temperature processing steps. The BASE-CONTACT mask is generally not used for n-type wafers as aluminum makes good electrical contact to the typical p-type base diffusion.

The GATE mask is used whenever a thin, high quality oxide is needed for the

MOS devices. During this step, which follows the diffusions, the previous

oxide is removed in the areas delineated by the GATE mask and new oxide is

grown

.

4
2 . TEST STRUCTURES

This section discusses the notation used on the drawings of the test structures which follow in sections 3 through 7. The structures are grouped in

five major categories: resistors, MOS capacitors, diodes, transistors, and

miscellaneous. The new structures on the pattern were designed using the

same design rules as for test pattern NBS-3 [1]

.

In the following sections both a detailed top view layout and cross sectional

view of each test structure are given. Figure 2 illustrates the scheme used.

In the top views and in the horizontal direction for cross sectional views,

the distance between grid lines represents 0.50 mil (12.7 um) . In the cross

sectional views, metal regions are black and oxide regions are dotted. All

oxide areas are shown with a thickness of one unit above the silicon surface

with the exception of gate oxide regions which are only a half unit thick.

In top views the gate oxide regions are denoted by dashed lines as there is

frequently not a line in the cross sectional view to indicate the boundary of

the gate oxide. Regions with a base diffusion are clear and indicated by a solid line two units below the silicon surface. Regions with an emitter diffusion are clear and indicated by a solid line one unit below the silicon sur- face. Regions with a base-contact diffusion are clear and indicated by a solid line one-half unit below the silicon surface. (In these views a unit

is the distance between adjacent grid lines. Also the silicon surface is assumed to be flat for the sake of simplicity; the incorporation of silicon into the oxide during thermal oxidation has been ignored.)

The following notation is used to define metal contact pads on the top view

of the drawings

B = base contact G = gate contact Ii, 1 2 = current contacts

C = collector contact S = source contact Vi , V2 = voltage contacts

E = emitter contact D = drain contact

Figure 2. An illustration of the notation used in views of a test structure.

The emitter diffusion is used for emitter regions of a bipolar transistor,

channel stop (CS) regions, and low-resistance contacts to the collector. The

base diffusion provides both bipolar transistor base regions and MOS transistor source-drain regions.

5
3. RESISTORS

3.1 Base Sheet Resistor

(Greek Cross)

Structure 4.22

3.3 Base Sheet Resistor

(Greek Cross)

Structure 4.25

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(Greek Cross)

Structure 4.24

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Structure 4

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6
3 . 5 Base Shee t Re sistor (van der Pauw, field plate, channel stop)

Structure 4.11
3.6 Incremental Base Sheet Resistor (van der Pauw)

Structure 4.35

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3.7 Base Sheet Resistor (Bridge)

Structure 4.33

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Base Sheet Resistor 3.9 Base-under-Emitter Sheet Res

(Bridge) (Greek Cross)

Structure 4.23 Structure 4.20
3.10 Base-Contact Sheet Resistor

(Greek Cross)

Structure 4.21

3.11 Emitter Sheet Resistor

(Offset Quadrate Cross)

Structure 4.28

3.12 Emitter Sheet Resistor (Bridge)

Structure 4.32

1

-1

1

t 1 e t r

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1

1 -1

10
3.13 Metal Sheet Resistor

(Greek Cross)

Structure 4.19

11
3.16 Collector Four-Probe Resistors

Structure 4.9, pipes 0.50 mil (12.7 um) on a side

X

Other similar structures, which differ primarily in pipe size, are:

Structure 4.1, pipes 0.20 mil (5.1 ym) on a side

Structure 4.5, pipes 0.30 mil (7.5 ym) on a side

Structure 4.7, pipes 0.40 mil (10.2 ym) on a side

Structure 4.17, pipes 0.25 mil (6.4 ym) on a side

12
3.17 Collector Hall Effect Device (van der Pauw)

Structure 4.31

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3.18 Metal Step-Coverage Resistor

Structure 4.38

I

13
3.19 Collector Spreading Resistor

Structure 4.18

14
15
4.2 MOS Capacitor over Collector (Emitter DGR)

Structure 4 .

3
4.3 MOS Capacitor over Collector (Field Plate, Channel Stop)

Structure 4.8

4.4 MOS Capacitor over Collector

Structure 4.30

17
18
19
5.2 Base-Collector Diode (Field Plate, Channel Stop)

Structure 4.14

6. TRANSISTORS

6.1 Bipolar Transistor

Structure 4.13

20
6.2 MOS Transistor (Circular)

Structure 4.15
6.3 MOS Transistor

Structure 4.16

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-1—t—

t

444444 -4-4-444 —1—1-—H- —H- ttH —(- 4—i- —U-\ M—

f

-i —-t —i

-H-l

- --H-+ H- — —

H

—h++4

4-

: t-44*+-

i

i i

i

; i 4-t- -M-i

-1-4- j

i i —I—j

44- 1 4 M—_j

ff -j- k

hi

L-i

4- -—j- rh~H-t 4 j ! 1 4-—

i J ±4+4 hi4 —H- -ii

' j—

L

22
7. MISCELLANEOUS

7.1 Alignment Markers for Negative Photoresist

Structure 4.4 N

—._ »

1 t "4

| --- := \

:= T

._J ._J

-

LwH. —

p

- -

i- 1 'it Ft— F +

-

-

\

- -

>m-i

ft

._.

11-

i

* This structure will also work with positive photoresist.

23
7.2 Alignment Markers for Positive Photoresist

Structure 4.4 P

j / c

V! r %b >

\i\ >q t T 1 i —

-j

i Jlr f ISJ 1 1 T#" 1

°k41 1 ft

it

-

> U 4 T t p

-\

f i

7.3 NBS Logo

Structure 4.6

. , , ,

\

1 1 1

!

!

I | St

! r

-1 4

El 1 r

4 £~ + ' < \\ c

O j

.J J

_iu -

\

-

- ru

L4 i~ im

N

n 1

r

24
7.4 Surface Profilometer Structure

Structure 4.34

25
7.5 Etch Control Structures

Structures 4.36 B, E, C, M , BC, G

,£1 i. . t 1

m Sk tr t g ,1a :

7.6 Resolution Structures

Structures 4.37 B, E, C, M, BC , G

26
REFERENCES

1. Buehler, M. G. , Semiconductor Measurement Technology: Microelectronic

Test Pattern NBS-3 for Evaluating the Resistivity-Dopant Density Relationship of Silicon, NBS Special Publication 400-22 (May 1976) .

2. Buehler, M. G. , and Thurber, W. R. , A Planar Four-Probe Test Structure

for Measuring Bulk Resistivity, IEEE Trans. Electron Devices ED-23,

968-974 (1976)

.

3. Buehler, M. G. , and Thurber, W. R. , An Experimental Study of Various

Cross Sheet Resistor Test Structures, J. Electrochem . Soc. 125 , 645-650

(1978)

.

4. Brown,. D. M. , Connery, R. J., and Gray, P. V., Doping Profiles by MOSFET

Deep Depletion C (V) , J. Electrochem. Soc. 122 , 121-127 (1975).

5. Koyama, R. Y., and Buehler, M. G. , Semiconductor Measurement Technology,

W. M. Bullis, Ed., NBS Special Publication 400-17, pp. 8-11,26-27 (November 19 75)

.

6. Mattis, R. L. , and Buehler, M. G. , A New Method for Calculating Background Dopant Density from p-n Junction Capacitance-Voltage Measurements,

J. Electrochem. Soc. 124, 1918-1923 (1977).

7. Buehler, M. G. , and Sawyer, D. E., Microelectronic Test Patterns Aid

Production of Custom ICs, Circuits Manufacturing No. 2, 45-56

(February 1977)

.

8. Buehler, M. G. , David, J. M. , Mattis, R. L., Phillips, W. E., and Thurber, W. R. , Semiconductor Measurement Technology: Planar Test Structures for Characterizing Impurities in Silicon, NBS Special Publication

400-21 (December 1975)

.

9. Buehler, M. G., Dopant Profiles Determined from Enhancement Mode MOSFET

d-c Measurements, Appl. Phys. Letters 3^, 848-850 (1977).

10. Brooks, R. D. , and Mattes, H. G. , Spreading Resistance Between Constant

Potential Surfaces, Bell System Tech. J. 5_0, 775-784 (1971) .

111. Saltich, J. L. , Volk, C. E., and Clark, L. E., Use of Specific Emitter

Efficiency in Evaluation and Design of Bipolar Transistors, Proc. IEEE

61, 680-681 (1973)

.

12. David, J. M. , and Buehler, M. G. , A Numerical Analysis of Various Cross

Sheet Resistor Test Structures, Solid-State Electronics 2_0, 539-543

(1977).

|l3. Buehler, M. G. , Grant, S. D., and Thurber, W. R. , Bridge and van der

Pauw Sheet Resistors for Characterizing the Line Width of Conducting

Layers, J. Electrochem. Soc. 125 , 650-654 (1978)

.

14. Chwang, R. , Smith, B. J., and Crowell, C. R. , Contact Size Effects on

the van der Pauw Method for Resistivity and Hall Coefficient Measurements, Solid-State Electronics 17, 1217-1227 .(1974).

27
APPENDIX

In the following figures, the center-to-center distance between the scribe

lines is 100 mil (2.54 mm). For all masks except the METAL mask the areas delineated for subsequent diffusion, oxidation, or oxide removal appear whi

in the photomicrographs of the masks. On the METAL mask the metallization

pattern is black on a white background.

Table 2 — Test Structures Shown in Figures 3-9.

Number Test Structure

4.1 Collector resistor (pipes 0.20 mil on a side)

4.2 MOS capacitor over collector (base DGR)

4.3 MOS capacitor over collector (emitter DGR)

4.4 Alignment markers

4.5 Collector resistor (pipes 0.30 mil on a side)

4 . 6 Logo

4.7 Collector resistor (pipes 0.40 mil on a side)

4.8 MOS capacitor over collector (FP, CS)

4.9 Collector resistor (pipes 0.50 mil on a side)

4.10 Base-collector diode (FP, CS)

4.11 Base sheet resistor (VDP, FP , CS)

28
Figure 3. Quadrant 1 of test pattern NBS-4. Test structures are identified

in table 2.

29

Figure 4. BASE mask for quadrant 1 of test pattern NBS-4. Test structures

located in this quadrant are listed in table 2.

31

Figure 5. BASE- CONTACT mask for quadrant 1 of test pattern NBS-4. Test

structures located in this quadrant are listed in table 2.

33

Figure 6. EMITTER mask for quadrant 1 of test pattern NBS-4. Test structures

located in this quadrant are listed in table 2.

35
I





Table 3 — Test Structures Shown in Figures 10-16.

Number Test Structure

4. 12 Mf)^ ranAfi "f~ (~) T~ CWT&T' ]~»^Q^

4. 13 Binol IS -L. _[_ arJ_ tTansi L_. J_ U. 1 1 O _l_ <;f O UVoi*J_ 4. 14 Racp-pnl 1 ppf nr H i nH p ("PT>

4. 15 MO^VFT fpirpnlar W/T, = 1 P 1

)

llv ± Hi ± \v_J_J_V_H_Ldl. j VV/J_| — J- O * J

A4 . lb

4. 17 Collector resistor (pipes 0.25 mil on a side)

4. 18 Collector spreading resistor

4. 19 Metal sheet resistor (Greek cross)

4. 20 Base-under-emitter sheet resistor (Greek cross)

4

.

21 Base-contact sheet resistor (Greek cross)

4. 22 Base sheet resistor (narrow Greek cross)

4. 23 Base sheet resistor (bridge, W/L = 0.25)

4. 24 Base sheet resistor (Greek cross)

4. 25 Base sheet resistor (Greek cross, tab contacts)

4. 26 Base sheet resistor (offset quadrate cross)

4. 27 Metal-to-emitter contact resistor

4. 28 Emitter sheet resistor (offset quadrate cross)

4. 29 Metal-to-base contact resistor

4. 30 MOS capacitor over collector (square)

42

1

;
Figure 12. BASE -CONTACT mask for quadrant 2 of test pattern NBS-4. Test

structures located in this quadrant are listed in table 3.

47

Figure 13. EMITTER mask for quadrant 2 of test pattern NBS-4. Test structures located in this quadrant are listed in table 3.

49

Figure 14. GATE mask for quadrant 2 of test pattern NBS-4. Test structures

located in this quadrant are listed in table 3.

51

Figure 15. CONTACT mask for quadrant 2 of test pattern NBS-4. Test structures located in this quadrant are listed in table 3.

53

I W ==!= sMJOl

Figure 16. METAL mask for quadrant 2 of test pattern NBS-4. Test structures

located in this quadrant are listed in table 3.

55
Table 4 — Test Structure Shown in Figures 17-23.

Number Test Structure

4.31 Hall effect device (VDP)

56
Figure 17. Quadrant 3 of test pattern NBS-4. The only test structure in

this quadrant is the Hall effect device listed in table 4.

57

Figure 18. BASE mask for quadrant 3 of test pattern NBS-4. The Hall effect device is the only test structure located in this quadrant. This figure is included for completeness even though the structure has no base diffusion

59

Figure 19. BASE-CONTACT mask for quadrant 3 of test pattern NBS-4. The Hall

effect device is the only test structure located in this quadrant. This figure is included for completeness even though the structure has no base contact

diffusion

.

61



Figure 21. GATE mask for quadrant 3 of test pattern NBS-4 . The Hall effect

device is the only test structure located in this quadrant. The GATE mask

is not involved in the fabrication of this structure, but it does remove oxide from the scribe lines surrounding the structure.

65
i
Figure 22. CONTACT mask for quadrant 3 of test pattern NBS-4. The Hall

feet device is the only test structure located in this quadrant.

67

69
Table 5 — Test Structures Shown in Figures 24 -30.

Number Test Structure

4. 32 Emitter sheet resistor (bridge, W/L = 0.25)

4.33 Base sheet resistor (bridge, W/L = 0. 25)

4.34 Surface profilometer structure

4. 35 Incremental base sheet resistor (VDP)

4. 36 Etch-control structures

4. 37 Resolution structures

4.38 Metal step-coverage resistor

70
Figure 24. Quadrant 4 of test pattern NBS-4. Test structures are identified

in table 5.

71

Figure 25. BASE mask for quadrant 4 of test pattern NBS-4. Test structures

located in this quadrant are listed in table 5.

73

Figure 26. BASE-CONTACT mask for quadrant 4 of test pattern NBS-4. Test

structures located in this quadrant are listed in table 5.

75
i

I

i
Figure 27. EMITTER mask for quadrant 4 of test pattern NBS-4. Test structures located in this quadrant are listed in table 5.

77

gure 28. GATE mask for quadrant 4 of test pattern NBS-4-. Te

cated in this quadrant are listed in table 5.

79

Figure 29. CONTACT mask for quadrant 4 of test pattern NBS-4. Test str

tures located in this quadrant are listed in table 5.

81
t
U. S. GOVERNMENT PRINTING OFFICE : 1978—261-238/56 83

NBS-114A (REV. 7-73)

r U.S. DEPT. OF COMM. BIBLIOGRAPHIC DATA

SHEET

1. PUBLICATION OR REPORT NO. NBS SP-400-32

2. Gov't Accession

No.

3. Recipient's Accession No.

TITLE AND SUBTITLE

Semiconductor Measurement Technology:

Microelectronic Test Pattern NBS-4

5. Publication Date April 1978

6. Performing Organization Code

A UTH OR (S

)

W. Robert Thurber and Martin G. Buehler

8. Performing Organ. Report No.

9. PERFORMING ORGANIZATION NAME AND ADDRESS

NATIONAL BUREAU OF STANDARDS

DEPARTMENT OF COMMERCE

WASHINGTON, D.C. 20234

10. Project/Task/Work Unit No. 4256372

11. Contract/Grant No. ARPA Order No. 2397

12. Sponsoring Organization Name and Complete Address (Street, City, State, ZIP) ARPA - 1400 Wilson Blvd., Arlington, Virginia 22209

NBS - Washington, D. C. 20234

13. Type of Report & Period Covered NBS Spec. Publ

.

14. Sponsoring Agency Code

15. SUPPLEMENTARY NOTES

Library of Congress Catalog Card Number; 78-606024

ljl6. ABSTRACT (A 200-word or less factual summary of most significant information. If document includes a significant

J bibliography or literature survey, mention it here.)

Microelectronic test pattern NBS-4 is a revision of test pattern NBS-3 which

was designed primarily for evaluation of the resistivity-dopant density relationship in silicon. Major changes include the addition of optional BASECONTACT and GATE masks and the incorporation of several new structures, some

useful for the resistivity-dopant density work, and others, mostly sheet resistors, included for evaluation of new designs.

!' The NBS-4 pattern contains 38 test structures such as planar four-probe resis11 tors, sheet resistors, M0S capacitors, p-n junctions, bipolar and M0S transistors, Hall effect device, and process control structures. The overall pattern

is a square 200 mil (5.08 mm) on a side and is divided into four quadrants which

are separated by scribe lines. A detailed layout of each structure is presented

including both a top view and a cross sectional view. Photomicrographs of each

quadrant and the quadrants of the six masks used in the fabrication of the pattern are shown in an appendix.

17. KEY WORDS (six to twelve entries; alphabetical order; capitalize only the first letter of the first key word unless a proper name; separated by semicolons

)

Dopant density; microelectronics; M0S capacitors; n-p-n transistor fabrication; p-n

junctions; resistivity; semiconductor electronics; sheet resistors; silicon; test

pattern; test structures.

18. AVAILABILITY |xH Unlimited

|

I For Official Distribution. Do Not Release to NTIS

|"~x! Order From Sup. of Doc, U.S. Government Printing Office Washington, D.C. 20402, SD Stock No. SN00L-QP3 -

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