EIA-477-A-1990 Cultured Quartz.pdf

1、EIA 477-A 90 323Yb00 0070839 7 ANSI/ EIA-477-A-1990 APPROVED: July 5, 1990 EIA STANDARD Cultured Quartz EIA-477-A (Revision of EIA477 and inclusion of EiA-477-1 -A) SEPTEMBER 1990 ELECTRONIC INDUSTRIES ASSOCIATION ENGINEERING DEPARTMENT EIA 477-A 90 m 3234600 0070820 3 m NOTICE EIA Engineering Stand

2、ards and Publications are designed to serve the public interest through eliminating misunderstandings between manufacturers and purchasers, facilitating interchangeability and improvement of products, and assisting the purchaser in selecting and obtaining with minimum delay the proper product for hi

3、s particular need. Existence of such Standards and Publications shall not in any respect preclude any member or nonmember of EIA from manufacturing or selling products not conforming to such Standards and Publications, nor shall the existence of such Standards and Publications preclude their volunta

4、ry use by those other than EIA members, whether the standard is to be used either domestically or internationally. Recommended Standards and Publications are adopted by EIA without regard to whether their adoption may involve patents on articles, materials, or processes. By such action, EIA does not

5、 assume any liability to any patent owner, nor does it assume any obligation whatever to parties adopting the Recommended Standard or Publication. This EIA Standard is considered to have International Standardization implication, but the International Electrotechnical Commission activity has not pro

6、gressed to the point where a valid comparison between the EIA Standard and the IEC document can be made. This Standard does not purport to address all safety problems associated with its use or all applicable regulatory requirements. It is the responsibility of the user of this Standard to establish

7、 appropriate safety and health practices and to determine the applicability of regulatory limitations before its use. Published by ELECTRON IC INDUSTRI ES ASSOCIATION Engineering Department 2001 Pennsylvania Ave., N.W. Washington, D.C. 20006 PRICE: $1 5.00 Copyright 1990 All rights reserved Printed

8、in U.S.A. EIA 477-A 90 m 3234b00 0070821 5 9 Q CULTURED QUARTZ TABLE OF CONTENTS Paragraph 1. Scope 2. Historical Perspective 3. Terms, Definitions and Procedures . 3.1 Cultured Quartz Crystal; also called Synthetic Quartz Crystal 3.2 Seed 3.3 Orientation and Handedness 3.4 Growth Zones 3.5 Dimensio

9、ns 3.6 Orientation of Predimensioned and Preoriented (Lumbered) Quartz 3.7 Infrared Quality, Alpham 3.8 Inclusions 3.9 Etch Channels 3.10 Aluminum Content 3.11 Swept Quartz 4. Requirements 4.1 Orientation 4.2 Handedness 4.3 Cultured Quare Crystal Dimensions 4.4 Seed Dimension 4.5 Mechanical Imperfec

10、tions 4.6 Alph% 4.7 Aluminum Content 4.8 Lumbered Quartz Requirements 5. Marking FIGURES FIGURE 1 Growth Zones of a Cultured Quartz Crystal Grown on a ZCut Seed. View is of Section Perpendicular to Y or Y-Prime Direction. FIGURE iA Cross Section of a Lumbered Quartz Bar. View is of Section Perpendic

11、ular to the Y or Y-Prime Direction. FIGURE 2 Y-Bar and AT-cut REFERENCES i EIA 477-A 90 m 3234600 O070822 7 = L . EIA-477-A Page 1 - CULTURED QUARTZ (From EIA Standards Proposal No. 2110 for updating EIA-477 and inclusion of EIA-477-1-A, formulated under the cognizance of EIA P-11 Committee on Piezo

12、electric Devices.) 1. SCOPE This document relates to crystalline quartz produced by hydrothermal growth intended to be used as raw material for piezoelectric crystal devices. 2. HISTORICAL PERSPECTIVE After cultured quartz was introduced commercially (1956), Q capability became and implicitly remain

13、s its main quality figure of merit. Inclusions, seed veils, etch channels, dislocations and impurities were all observed then, but their effects on resonator performance were undetected in material whose Q capability was in control, Q capability of cultured quartz was most sensitively observed in th

14、e Warner designed 5 MHz fifth overtone frequency standard resonator, because all the sources of its frictional losses other than the internal friction of the material were minimized. Qs significance in a frequency control device is that it governs the precision of the resonators frequency response.

15、Cultured quartz users wanted a Q capability greater than the Qs needed in the resonator designs being manufactured. Later it was observed empirically that material meeting a Q minimum test requirement also showed an “in control angle behavior“ relationship of its AT cut frequency/temperature curves

16、with respect to cut wafer angles. In 1965 Fraser showed that the main source of Q-limiting internal friction in cultured quartz, its OH content, could also be measured through its infrared (IR) absorption in the well known OH absorption band. Together with Rudd, he identified wavelengths that serve

17、usefully to indicate OH concentrations in cultured quartz, and they developed an empirical alph%,/5 MHz Q relationship. The infrared absorption per cm at 3500 wavenumbers can be measured simply, quickly, inexpensively, and in smaller quartz specimens, than the 5 MHz Qs of fabricated resonators. The

18、IR method soon became the preferred and widely accepted method for obtaining Q indications for use in the quality control of cultured quartz. measured by the long-used above procedure, to become the main quality in 1985 the EIA chose alph indicator for cultured quartz. bypasses confusion about corre

19、lating alphas with 5 MHz Qs, or with Qs at various frequencies. Unlike Q, the alpha, measurement, and OH content, are independent of resonator frequency. The five 5 MHz Q grade test hits that had been accepted in terms of Q indications from alph% measurements, by the EIA in 1981 (and four matching g

20、rades by the IEC in 1983) are preserved unchangeE alpha terms. They are restated as their five corresponding alphh grade test limits, together with the letter grade labels (A, B, C, D and E). e w EIA 477-A 90 = 3234b00 O070823 9 . EIA-477-A Page 2 Z Z FIGURE 1 GROWTH ZONES OF A CULTURED QUARTZ CRYST

21、AL GROWN ON A ZCUT SEED. VIEW IS OF SECTION PERPENDICULAR TO Y OR Y-PRIME DIRECTION Basai Face Height EIA 477-A 90 m 3234600 O070824 O m EIA-477-A Page 3 It is widely accepted that the alpha, also serves as a control of the frequency/temperature curve vs. angle of AT cut behavior of cultured quartz.

22、 %r most AT applications, Grade C quartz (having an alpha, less than 0.06 per cm) yields an f/T behavior closely approximating the range experienced using natural quartz. Grades B and A can be required if tighter control of the f/T behavior and higher quality is needed. Although they are not ordinar

23、ily required, additional testing and grading information included here relates to: inclusion densities, etch channel densities, aluminum content and swept quartz. Each of these tests is pertinent to certain specific application needs - and need not be required for general use. The alpha grade limit

24、will ensure that defects are not present at densities sufficient to increase the OH content beyonyits specified grade maximum requirement. 3. TERMS, DEFINITIONS AND PROCEDURES 3.1 Cultured Quartz Crystal; also called Synthetic Quartz Crystal A single crystal of alpha SiO, grown by a hydrothermal met

25、hod. The crystal may be of either handedness. The terms and definitions in this section apply to crystals in as grown condition. 33 Seed The quartz crystal substrate upon which growth is induced in the hydrothermal growing process. 33 Orientation and Handedness a The orientation and handedness are a

26、s defined in IEEE Standard 176-1978. 3.3.1 The orientation and handedness of the cultured quartz crystal are the same as the orientation and handedness of the seed. 3.4 Growth Zones Growth zones are regions in the quartz deposited on the seed in which the growth is primarily in one crystal direction

27、. Terminology for growth zones is: Zgrowth, Greater-X growth, Lesser-X growth, and S-growth. (See Figure 1.) 3.5 Dimensions 3.5.1 As-grown Cultured or Synthetic Crystal The following dimensions pertain to growth on a Zcut seed rotated less than 20“ around the X-axis, or less than 30“ around the Zaxi

28、s. Standard dimensions pertaining to growth on a Zcut seed rotated more than 20“ around the X-axis are under consideration. 3.5.1.1 Length The length of the cultured quartz crystal is in the Y or Y-prime direction and is taken to be the length of the seed. 3.5.1.2 Width The width of the cultured qua

29、rtz crystal is in the Z or Zprime direction and is taken to be the smallest size in the Zdirection excluding regions of natural termination. d, .EIA 477-A 90 m 3234600 O070825 2 * t EM-477-A Page 4 3.5.1.3 Height The height of the cultured quartz crystal is in the X or X-prime direction. 3.5.1.3.1 G

30、ross height The gross height is the maximum size of the cultured quartz crystal in the X or X-prime direction. 3.5.1.3.2 Basal Face Height The basal face height of a cultured quartz crystal is measured in the X or X-prime direction. It is the minimum height of the Zgrowth measured at the width (2.5.

31、1.2) of the cultured quartz crystal. 3.5.2 Predimensioned and Preoriented (Lumbered) Quartz - Figure IA 3.5.2.1 Height and Seed Height The height and seed height of a lumbered quartz bar are in the X or X-prime direction. 3.5.2.2 Width and Seed Width The width and seed width of a lumbered quartz bar

32、 are in the Z or Z-prime direction. 3.5.2.3 Length The length of a lumbered quartz bar is in the Y or Y-prime direction and is taken to be the length of the seed. 0 3.5.2.4 Extended Seeh Width Extended seed width of a lumbered quartz bar is that portion of the bar parallel to and centered between th

33、e lumbered Z or Z-prime surfaces within which the seed is entirely contained. EIA 477-A 90 3234b00 007082b 4 m EIA-477-A Page5 - I I d-, Bar Width + Height X FIGURE iA CROSS SECTION OF A LUMBERED QUARTZ BAR. VIEW IS OF A SECON PERPENDICULAR TO THE Y OR Y-PRIME DIRECTION EIA 477-A 90 m 3234b00 O07082

34、7 b m EIA-477-A Page 6 3.5.2.5 Extended Seed Height The extended seed height of a lumbered quartz bar is that portion of the bar parallel to the X surfaces within which the seed is entirely contained. 3.5.2.6 Seed Centering, X-Direction The location of the extended seed height between the lumbered X

35、-surfaces is specified by dimensions from the seed to the adjacent lumbered X-surfaces. 3.6 Orientation of Predimensioned and Preoriented (Lumbered) Quartz 3.6.1 X-Reference Surface The orientation of the X or X-prime reference surface is specified with respect to the X-direction by rotations about

36、the Y and Z axes. 3.6.2 Z-Surfaces The orientation of the Z (Z) surfaces is specified with respect to the Zdirection by rotation about the X and Y axes, 3.7 Infrared Quality, by AlphaJ, measurement; the principal Quality Indicator (sufficient in many resonator applications) The infrared absorption p

37、er cm at 3500 wave numbers is measured over a Y-cut slice scan as the difference between the absorption at the wave number 3500 cm- and absorption in the background outside the band, at 3800 cm- , or at 3979 cm- when using a single beam instrument. 3.7.1 Preparation of the Y-cut slice The cultured q

38、uartz crystal to be sampled is mounted on a substrate using a bonding wax or adhesive, then sliced in a quartz cut-off saw to yield at least one Y-cut slice the thickness of which, after lapping and polishing, should fall in the range of 5.0 to 10.0 mm. The 5.0 mm thickness is appropriate for high a

39、lpha material, to resolve its alpha variations; the mid range for medium alphas; and the 10.0 mm thickness is appropriate for the lowest alpha material to measure its smali absorption. After sawing, the slice is lapped on both major surfaces: first, with a homogenized mixture of 25 micron abrasive;

40、second, with a homogenized mixture of 3 micron abrasive. A minimum of 0.25 mm total thickness of quartz shall be removed in the first abrasive lapping, and of 0.10 mm total thickness in the second abrasive lapping. Further lapping to polish is optional, and is preferred for low alphas. 3.7.2 Calibra

41、tion of a standard Y-Cut slice in an IR spectrophotometer The infrared spectrophotometer is turned on, allowed to warm up and fully stabilize, and then calibrated. The normal daily calibration will include its transmission (O-lO%) or absorbance (logT = 1.0-0) limit settings, chart speed and synchron

42、ized sample scanning arrangement. For evaluation and normal use a 1.5 mm width aperture is located in the sample beam. The apertures height should not exceed the X dimension of the seed or 4.5 mm. A polished Y-cut standard reference slice is placed first in the sample holder, which is then mounted i

43、n the scanning device. EIA 477-A 90 m 3234b00 0070828 8 = EIA-477-A Page 7 The wave number control is set at a background setting, (outside, but near the OH absorption band) usually 3800 - + 3 cm-, and the sample is translated through the beam with synchronized chart advance at the fmed wave number.

44、 Such scanning is done only in the Zgrowth zones of the Y-cut slice (iustrated in Figs. 1 and lA). In certain cases where background noise may be a problem, such as single beam operation, a higher background wave number, 3979 2 3, may be used for lowered background noise. If the background scan trac

45、e is not reasonably flat outside the original seeds boundaries, a thin film of fluorolube grease should be applied to both major surfaces of the semi-polished Y-cut slice. Baseline changes should not exceed 0.02 absorption unit during a background scan. After completing a successful scan at backgrou

46、nd, the wave number is adjusted to 3500 +. 3 cm-. The sample is returned to its original position and the chart paper is rerolled to the position where its wave number scan began. The sample is then scanned to plot its infrared absorption at this wave number. The calibration a-values (maximum and mi

47、nimum) are calculated from this reference scan, using the equation: A -A 3500 cm- 3800 cm- Y-cut slice thickness in cm o= Note: “A is the logarithm (base 10) of the fraction of incident beam absorbed by the sample at the subscript wave number. The spectrophotometer is considered in proper calibratio

48、n if its CY maximum and CY minimum readings are repeatable within d, 0.004 unit of the standards values for them. 3.7.3 Test Measurement of a Y-cut Slice After successful calibration each prepared unknown slice is scanned at the background and the 3500 OH absorption band wave numbers, using a thin f

49、iim of fluorolube grease as needed in cases where there is less than a full polish. Their pertinent alpha values are calculated using the equation above. Regions excluded from this determination are f. 2.0 mm from the seed center, and the excess growth beyond the appropriate pre- dimensioned bar dimensions. 3.8 Inclusions Any foreign material within a cultured quartz crystal visible under 3OX magnification. 3.8.1 Seed Veil The array of inclusions or cracks at the surfaces of the seed upon which a crystal has been grown. 3.8.2 Bubbles Voids, often partiall