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                                                                     Exhibit 3.4

                       CABOT MICROELECTRONICS CORPORATION
                     CERTIFICATE OF DESIGNATION, PREFERENCES
                   AND RIGHTS OF SERIES A JUNIOR PARTICIPATING
                                 PREFERRED STOCK
                            (Pursuant to Section 151
            of the General Corporation Law of the State of Delaware)


         We, Matthew Neville, the President and Chief Executive Officer, and
William C. McCarthy, Chief Financial Officer and Secretary of Cabot
Microelectronics Corporation, a corporation organized and existing under the
General Corporation Law of the State of Delaware (the "Corporation"), in
accordance with the provisions of Section 151 thereof, do hereby certify;

         The Board of Directors, at a meeting held on March 24, 2000, adopted
the following resolution to create, upon the filing with the Secretary of State
of the State of Delaware, and the effectiveness of (the "Effective Time"), the
Corporation's Amended and Restated Certificate of Incorporation (the
"Certificate of Incorporation"), a series of fifty thousand (50,000) shares of
Preferred Stock designated as Series A Junior Participating Preferred Stock;

         WHEREAS, the Certificate of Incorporation will provide that the
Corporation is authorized to issue 20,000,000 shares of Preferred Stock, none of
which are currently issued and outstanding, now therefore it is:

         RESOLVED, that pursuant to the authority vested in the Board of
Directors of the Corporation by Article IV of the Certificate of Incorporation
(as defined below), a series of Preferred Stock of the Corporation shall, upon
the Effective Time, be created out of the authorized but unissued shares of the
capital stock of the Corporation, such series to be designated Series A Junior
Participating Preferred Stock (the "Participating Preferred Stock"), to consist
of 50,000 shares, par value $.001 per share, of which the preferences and
relative and other rights, and the qualifications, limitations or restrictions
thereof, shall be as follows:

                  1. Future Increase or Decrease. Subject to paragraph 4(e) of
this resolution, the number of shares of said series may at any time or from
time to time be increased or decreased by the Board of Directors notwithstanding
that shares of such series may be outstanding at such time of increase or
decrease.

                  2.  Dividend Rate.

                         (a) The holders of shares of Participating Preferred
Stock shall be entitled to receive, when, as and if declared by the Board of
Directors out of funds legally

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available for the purpose, quarterly dividends payable in cash on the first day
of each January, April, July and October in each year (each such date being
referred to herein as a "Quarterly Dividend Payment Date"), commencing on the
first Quarterly Dividend Payment Date after the first issuance (the "First
Issuance") of a share or fraction of a share of Participating Preferred Stock,
in an amount per share (rounded to the nearest cent) equal to the greater of (i)
$10.00 and (ii) 1,000 times the aggregate per share amount of all cash dividends
and 1,000 times the aggregate per share amount (payable in kind) of all non-cash
dividends or other distributions, other than a dividend or distribution payable
in shares of Common Stock, par value $.001 per share, of the Corporation
("Common Stock") or by way of a subdivision of the outstanding shares of Common
Stock (by reclassification or otherwise), declared on the Common Stock, since
the immediately preceding Quarterly Dividend Payment Date, or, with respect to
the first Quarterly Dividend Payment Date, since the first issuance of any share
or fraction of a share of Participating Preferred Stock. In the event the
Corporation shall at any time after the First Issuance declare or pay any
dividend on the Common Stock payable in shares of Common Stock, or effect a
subdivision or combination or consolidation of the outstanding shares of Common
Stock (by reclassification or otherwise than by payment of a dividend in shares
of Common Stock) into a greater or lesser number of shares of Common Stock, then
in each such case the amount to which holders of shares of Participating
Preferred Stock were entitled immediately prior to such event under the
preceding sentence shall be adjusted by multiplying such amount by a fraction,
the numerator of which is the number of shares of Common Stock outstanding
immediately after such event and the denominator of which is the number of
shares of Common Stock that were outstanding immediately prior to such event.

                           (b) On or after the First Issuance, no dividend on
Common Stock shall be declared unless
concurrently therewith a dividend or distribution is declared on the
Participating Preferred Stock as provided in paragraph (a) above; and the
declaration of any such dividend on the Common Stock shall be expressly
conditioned upon payment or declaration of and provision for a dividend on the
Participating Preferred Stock as above provided. In the event no dividend or
distribution shall have been declared on the Common Stock during the period
between any Quarterly Dividend Payment Date and the next subsequent Quarterly
Dividend Payment Date, a dividend of $10.00 per share on the Participating
Preferred Stock shall nevertheless be payable on such subsequent Quarterly
Dividend Payment Date.

                           (c) Whenever quarterly dividends or other dividends
payable on the Participating Preferred
Stock as provided in paragraph (a) above are in arrears, thereafter and until
all accrued and unpaid dividends and distributions, whether or not declared, on
shares of Participating Preferred Stock outstanding shall have been paid in
full, the Corporation shall not redeem or purchase or otherwise acquire for
consideration shares of any stock ranking junior (either as to dividends or upon
liquidation, dissolution or winding up) to the Participating Preferred Stock,
provided that the Corporation may at
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any time redeem, purchase or otherwise acquire shares of any such junior stock
in exchange for shares of any stock of the Corporation ranking junior (as to
dividends and upon dissolution, liquidation or winding up) to the Participating
Preferred Stock.

                         (d) Dividends shall begin to accrue and be cumulative
on outstanding shares of Participating Preferred Stock from the Quarterly
Dividend Payment Date next preceding the date of issue of such shares of
Participating Preferred Stock, unless the date of issue of such shares is prior
to the record date for the first Quarterly Dividend Payment Date, in which case
dividends on such shares shall begin to accrue from the date of issue of such
shares, or unless the date of issue is a Quarterly Dividend Payment Date or is a
date after the record date for the determination of holders of shares of
Participating Preferred Stock entitled to receive a quarterly dividend and
before such Quarterly Dividend Payment Date, in either of which events such
dividends shall begin to accrue and be cumulative from such Quarterly Dividend
Payment Date. Accrued but unpaid dividends shall not bear interest. The Board of
Directors may fix a record date for the determination of holders of shares of
Participating Preferred Stock entitled to receive payment of a dividend
distribution declared thereon, which record date shall be no more than 30 days
prior to the date fixed for the payment thereof.

         3. Dissolution, Liquidation and Winding Up. In the event of any
voluntary or involuntary dissolution, liquidation or winding up of the affairs
of the Corporation (hereinafter referred to as a "Liquidation"), the holders of
Participating Preferred Stock shall be entitled to receive the greater of (a)
$10.00 per share, plus an amount equal to accrued and unpaid dividends and
distributions thereon, whether or not declared, to the date of such payment and
(b) the aggregate amount per share equal to 1,000 times the aggregate amount to
be distributed per share to holders of Common Stock (the "Participating
Preferred Liquidation Preference"). In the event the Corporation shall at any
time after the First Issuance declare or pay any dividend on the Common Stock
payable in shares of Common Stock, or effect a subdivision or combination or
consolidation of the outstanding shares of Common Stock (by reclassification or
otherwise than by payment of a dividend in shares of Common Stock) into a
greater or lesser number of shares of Common Stock, then in each such case the
aggregate amount to which holders of shares of Participating Preferred Stock
were entitled immediately prior to such event under the preceding sentence shall
be adjusted by multiplying such amount by a fraction the numerator of which is
the number of shares of Common Stock outstanding immediately after such event
and the denominator of which is the number of shares of Common Stock that were
outstanding immediately prior to such event.

         4. Voting Rights. The holders of shares of Participating Preferred
Stock shall have the following voting rights:

                         (a) Each share of Participating Preferred Stock shall
entitle the holder thereof to one thousand (1,000) votes on all matters
submitted to a vote of the stockholders of the Corporation. In the event the
Corporation shall at any time after the
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First Issuance declare or pay any dividend on the Common Stock payable in shares
of Common Stock, or effect a subdivision or combination or consolidation of the
outstanding shares of Common Stock (by reclassification or otherwise than by
payment of a dividend in shares of Common Stock) into a greater or lesser number
of shares of Common Stock, then in each such case the aggregate number of votes
to which holders of shares of Participating Preferred Stock were entitled
immediately prior to such event under the preceding sentence shall be adjusted
by multiplying such number by a fraction the numerator of which is the number of
shares of Common Stock outstanding immediately after such event and the
denominator of which is the number of shares of Common Stock that were
outstanding immediately prior to such event.

                           (b) Except as otherwise provided herein, or by law,
the Corporation's Restated Certificate
of Incorporation ("Certificate of Incorporation") or the Bylaws of the
Corporation (the "Bylaws"), the holders of shares of Participating Preferred
Stock and the holders of shares of Common Stock shall vote together as one class
on all matters submitted to a vote of stockholders of the Corporation.

                           (c) If and whenever dividends on the Participating
Preferred Stock shall be in arrears in an amount equal to six quarterly dividend
payments, then and in such event the holders of the Participating Preferred
Stock, voting separately as a class (subject to the provisions of subparagraph
(d) below), shall be entitled at the next annual meeting of the stockholders or
at any special meeting to elect two (2) directors. Each share of Participating
Preferred Stock shall be entitled to one vote, and holders of fractional shares
shall have the right to a fractional vote. Upon election, such directors shall
become additional directors of the Corporation and the authorized number of
directors of the Corporation shall thereupon be automatically increased by such
number of directors. Such right of the holders of Participating Preferred Stock
to elect directors may be exercised until all dividends in default on the
Participating Preferred Stock shall have been paid in full, and when so paid and
set apart, the right of the holders of Participating Preferred Stock to elect
such number of directors shall cease, the term of such directors shall thereupon
terminate, and the authorized number of directors of the Corporation shall
thereupon return to the number of authorized directors otherwise in effect, but
subject always to the same provisions for the vesting of such special voting
rights in the case of any such future dividend default or defaults. The fact
that dividends have been paid and set apart as required by the preceding
sentence shall be evidenced by a certificate executed by the President and the
Chief Financial Officer of the Corporation and delivered to the Board of
Directors. The directors so elected by holders of Participating Preferred Stock
shall serve until the certificate described in the preceding sentence shall have
been delivered to the Board of Directors or until their respective successors
shall be elected or appointed and qualify.

         At any time when such special voting rights have been so vested in the
holders of the Participating Preferred Stock, the Secretary of the Corporation
may, and upon the
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written request of the holders of record of 10% or more of the number of shares
of the Participating Preferred Stock then outstanding addressed to such
Secretary at the principal office of the Corporation in the State of Illinois,
shall call a special meeting of the holders of the Participating Preferred Stock
for the election of the directors to be elected by them as hereinabove provided,
to be held in the case of such written request within forty (40) days after
delivery of such request, and in either case to be held at the place and upon
the notice provided by law and in the Bylaws of the Corporation for the holding
of meetings of stockholders; provided, however, that the Secretary shall not be
required to call such a special meeting (i) if any such request is received less
than ninety (90) days before the date fixed for the next ensuing annual or
special meeting of stockholders or (ii) if at the time any such request is
received, the holders of Participating Preferred Stock are not entitled to elect
such directors by reason of the occurrence of an event specified in the third
sentence of subparagraph (d) below.

                         (d) If, at any time when the holders of Participating
Preferred Stock are entitled to elect directors pursuant to the foregoing
provisions of this paragraph 4, the holders of any one or more additional series
of Preferred Stock are entitled to elect directors by reason of any default or
event specified in the Certificate of Incorporation, as in effect at the time of
the certificate of designation for such series, and if the terms for such other
additional series so permit, the voting rights of the two or more series then
entitled to vote shall be combined (with each series having a number of votes
proportional to the aggregate liquidation preference of its outstanding shares).
In such case, the holders of Participating Preferred Stock and of all such other
series then entitled so to vote, voting as a class, shall elect such directors.
If the holders of any such other series (if designated) have elected such
directors prior to the happening of the default or event permitting the holders
of Participating Preferred Stock to elect directors, or prior to a written
request for the holding of a special meeting being received by the Secretary of
the Corporation from the holders of not less than 10% of the then outstanding
shares of Participating Preferred Stock, then such directors so previously
elected will be deemed to have been elected by and on behalf of the holders of
Participating Preferred Stock as well as such other series, without prejudice to
the right of the holders of Participating Preferred Stock to vote for directors
if such previously elected directors shall resign, cease to serve or fail to
stand for reelection while the holders of Participating Preferred Stock are
entitled to vote. If the holders of any such other series are entitled to elect
in excess of two (2) directors, the Participating Preferred Stock shall not
participate in the election of more than two (2) such directors, and those
directors whose terms first expire shall be deemed to be the directors elected
by the holders of Participating Preferred Stock; provided that, if at the
expiration of such terms the holders of Participating Preferred Stock are
entitled to vote in the election of directors pursuant to the provisions of this
paragraph 4, then the Secretary of the Corporation shall call a meeting (which
meeting may be the annual meeting or special meeting of stockholders referred to
in subparagraph (c)) of holders of Participating Preferred Stock for the purpose
of electing replacement directors (in accordance with the provisions of this
paragraph 4) to be held on or prior to the time of
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expiration of the expiring terms referred to above.

                         (e) Except as otherwise set forth herein or required by
law, the Certificate of Incorporation or the Bylaws, holders of Participating
Preferred Stock shall have no special voting rights and their consent shall not
be required (except to the extent they are entitled to vote with holders of
Common Stock as set forth herein) for the taking of any corporate action. No
consent of the holders of outstanding shares of Participating Preferred Stock at
any time outstanding shall be required in order to permit the Board of Directors
to: (i) increase the number of authorized shares of Participating Preferred
Stock or to decrease such number to a number not below the sum of the number of
shares of Participating Preferred Stock then outstanding and the number of
shares with respect to which there are outstanding rights to purchase; or (ii)
issue Preferred Stock which is senior to the Participating Preferred Stock,
junior to the Participating Preferred Stock or on a parity with the
Participating Preferred Stock.

                  5. Consolidation, Merger, etc. In case the Corporation shall
enter into any consolidation, merger, combination or other transaction in which
the shares of Common Stock are exchanged for or changed into other stock or
securities, cash and/or any other property, then in any such case each share of
Participating Preferred Stock shall at the same time be similarly exchanged or
changed into an amount per share, subject to the provision for adjustment
hereinafter set forth, equal to 1,000 times the aggregate amount of stock,
securities, cash and/or any other property (payable in kind), as the case may
be, into which or for which each share of Common Stock is changed or exchanged.
In the event the Corporation shall at any time after the First Issuance declare
or pay any dividend on the Common Stock payable in shares of Common Stock, or
effect a subdivision or combination or consolidation of the outstanding shares
of Common Stock (by reclassification or otherwise than by payment of a dividend
in shares of Common Stock) into a greater or lesser number of shares of Common
Stock, then in each such case the amount set forth in the preceding sentence
with respect to the exchange or change of shares of Participating Preferred
Stock shall be adjusted by multiplying such amount by a fraction, the numerator
of which is the number of shares of Common Stock outstanding immediately after
such event and the denominator of which is the number of shares of Common Stock
that were outstanding immediately prior to such event.

                  6. Redemption. The shares of Participating Preferred Stock
shall not be redeemable.

                  7. Conversion Rights. The Participating Preferred Stock is not
convertible into Common Stock or any other security of the Corporation.

                  8. Ranking. The Participating Preferred Stock shall rank
junior to all other classes and series of the Corporation's Preferred Stock as
to payment of dividends and the distribution of assets, unless the terms of any
such series shall provide otherwise.

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IN WITNESS WHEREOF, the undersigned President and Chief Executive Officer and
Secretary and General Counsel of the Corporation each declares under penalty of
perjury the truth, to the best of his knowledge, of this Certificate of
Designation, Preferences and Rights of Series B Junior Participating Preferred
Stock.

                  Executed this 29th day of March, 2000.



                                           By: -------------------------
                                           Name: Matthew Neville
                                           Title:  President and
                                           Chief Executive Officer

Attest:

- ------------------------
Name: William C. McCarthy
Title:Chief Financial Officer, Secretary

STATE OF ILLINOIS                   )
                                    ) ss.:
COUNTY OF ________                  )

         This instrument was acknowledged before me on March 29, 2000, by
Matthew Neville, as President and Chief Executive Officer of Cabot
Microelectronics Corporation and by William C. McCarthy, as Chief Financial
Officer and Secretary of Cabot Microelectronics Corporation They are personally
known to me and did not take an oath.

                                           -------------------------------------
                                           Name: -------------------------------
                                           Notary Public - State of Illinois
                                           My Commission Expires: