TW384394B

TW384394B - Method of monitoring the condition of chemical-mechanical polishing process

Info

Publication number: TW384394B
Application number: TW88105222A
Authority: TW
Inventors: Shiue-Jung Chen; Jian-Hung Chen; Jiun-Yuan Wu
Original assignee: United Microelectronics Corp
Priority date: 1999-04-01
Filing date: 1999-04-01
Publication date: 2000-03-11

Abstract

The present invention provides a method for monitoring the condition of chemical-mechanical polishing during processing of dielectric layer of a semiconductor chip, by which a light source of fixed wavelength is projected on the dielectric layer of the semiconductor at a predetermined angle. This shall occur within a predetermined time period after the chemical-mechanical polishing is started, and light reflection is generated herewith. The intensity of reflected light is monitored in a prescribed period of time to calculate the pattern of periodical change of the reflected light, basing on the value obtained. Thereafter, it is continuously monitored for the intensity of reflected light, according to the calculated pattern of periodical change, until the predetermined time expires. When irregularity in the intensity of reflected light is detected, which does not correspond with the pattern of periodical change during the testing period, the device will generate a output signal to stop the chemical-mechanical polishing process.

Description

...... ' ' * * .......， __________丨修正本付,(丨霣7見, 五、發明說明（1) 丨補充 —~一本發明係提供一種藍測方法，尤指一種用來監測一化學機械研磨製程狀態的監測方法。在半導《製程中，化學機械研磨 (chemica卜mechanical polishing，簡稱為 CMP)是一種全面性的平坦化技術，用來均勻地去除半導體晶片表面的沈積層。進行CMP製程時必須適當地監測，以避免製程錯誤或不當地研磨’而影響到製程良率。習知介電層CMp終點監測系統（end-point detection system)是利用光學、的原理來Μ測介電層的CMP製程以決定停止研磨的時間，也就是研磨终點。然而，習知介電層CMP光學终點監測系統缺乏持績檢驗研磨狀態是否合於規格的法則，倘若於研磨終點前CMP製程便發生錯誤，這種監測系統無法及時錯誤來停止製程。 ' 習知進行CMP製程的機台包含有一個基座用來承載被研磨的半導體晶片，以及一個具有一個孔洞的研磨墊設於基座上方’用來研磨半導«晶片的表面。機台舆液體輪送系統相連接’液體輪送系統則會輸送CMP製程所需要的研磨衆至機台上β進行介電層的CMP製程時，半導體晶片先被水平地固定於基座上，然後基座會以一定的速度旋轉。研磨衆則會被均勻地喷濃於旋轉的半導體晶片表面的介電層上’以使介電層發生化學反應。同時基座上方的研磨墊會向下觸磨半導體晶片表面，對旋轉的半導體晶表面進行...... '' * * ......., __________ 丨 Amend the payment, (丨霣 7 see, V. Description of the invention (1) 丨 Supplement— ~ This invention provides a blue test Method, especially a monitoring method used to monitor the state of a chemical mechanical polishing process. In the semi-conductor process, chemical mechanical polishing (CMP) is a comprehensive planarization technique used to uniformize Remove the deposited layer on the surface of the semiconductor wafer. The CMP process must be properly monitored to avoid process errors or improper grinding, which affects the process yield. Know the dielectric layer CMP end-point detection system. It uses the principle of optics to measure the CMP process of the dielectric layer to determine the time to stop polishing, that is, the polishing end point. However, it is known that the dielectric layer CMP optical end point monitoring system lacks performance to check whether the polishing status is in line with The rules of the specification, if the CMP process is wrong before the polishing end point, this monitoring system cannot stop the process in time and error. '' The machine used to perform the CMP process contains a base for carrying the researched Semiconductor wafer and a polishing pad with a hole above the base are used to grind the surface of the semiconductor «wafer. The machine is connected to the liquid carousel system 'and the liquid carousel system will transport the required CMP process. During the CMP process of the dielectric layer during the grinding process to the β on the machine, the semiconductor wafer is first fixed horizontally on the base, and then the base is rotated at a certain speed. The dielectric layer on the surface of the semiconductor wafer is used to chemically react the dielectric layer. At the same time, the polishing pad above the pedestal will touch the surface of the semiconductor wafer downward to perform the rotation of the semiconductor crystal surface.

第4頁五、發明說明（2) _ _ . 機械式研磨°在適當的製程參數設定下，利用研磨漿所提供的化學反應’以及研磨墊所提供的機械研磨，便能去除半導魏晶片表面上凸出的介電層。介電層的研磨终點，需要藉由介電層CMP終點監測系統來決定。介電層CMP終點監測系統便是藉由研磨墊上的孔洞，來監侧由介電層所反射的光線’以決定介電層的研磨终點。請參考圖一，圈一為習知介電層CMP终點監測系統之監測方法的示意圈。習知介電層CMp終點監測系統是於半導體晶片進行CMP製程時，藉由研磨墊上的孔洞，由一固定波長的光源以一預定的傾斜角度來照射半導髏晶片表面的介電層以產生反射光，並由與這個傾斜角度相對應的反射角度來監測反射光，然後持續於每個時間點量測並記錄反射光強度。圈一為依據反射光強度對研磨時間關係所形成的曲線’圈中所示之t是預先設定停止CMP製程的時間點，CMP製程會於12自動停止。而於CMP製程自動停止的時間點t象前，隨著研磨時間增加，厚度逐漸變薄的介電層所產生的反射光強度會明顢地改變，如t與t祠的曲線所示。當半導體晶片表面被過度研磨至介電層下方之其他材料層時，反射光強度會因材料性質不同而產生急遽的變化，為防止過度研磨，必須於發現反射光強度急遽變化時及時停止CMP製程。因此習知介電層CMP終點監測系統便是於持續監測反射光強度的過程中，於反射光強度明顯改變的時段△ t内偵測反射光強度的變化情形，以決定介電層5. Description of the invention on page 4 (2) _ _. Mechanical polishing ° With proper process parameter settings, the chemical reaction provided by the polishing slurry and mechanical polishing provided by the polishing pad can remove semiconductor wafers A protruding dielectric layer on the surface. The polishing end point of the dielectric layer needs to be determined by the dielectric layer CMP end point monitoring system. The dielectric layer CMP end point monitoring system monitors the light reflected by the dielectric layer through the holes on the polishing pad to determine the polishing end point of the dielectric layer. Please refer to Fig. 1. Circle 1 is a schematic circle of the monitoring method of the conventional dielectric layer CMP endpoint monitoring system. The conventional CMP endpoint monitoring system for dielectric layers is produced by irradiating a dielectric layer on the surface of a semiconductor wafer with a predetermined tilt angle from a hole on a polishing pad through a hole in a polishing pad during a CMP process of a semiconductor wafer. The reflected light is monitored by the reflection angle corresponding to this tilt angle, and then the reflected light intensity is measured and recorded at each time point. Circle 1 is a curve formed based on the relationship between the reflected light intensity and the polishing time. The t shown in the circle is a preset time point for stopping the CMP process, and the CMP process is automatically stopped at 12. However, before the time point t when the CMP process is automatically stopped, as the polishing time increases, the reflected light intensity produced by the gradually thinner dielectric layer will change drastically, as shown by the curve between t and t. When the surface of the semiconductor wafer is excessively ground to other material layers under the dielectric layer, the reflected light intensity will change sharply due to different material properties. In order to prevent excessive grinding, the CMP process must be stopped in time when a sharp change in the reflected light intensity is found. . Therefore, the conventional CMP endpoint monitoring system of the dielectric layer is used to continuously monitor the intensity of the reflected light, and detect the change of the intensity of the reflected light within a period Δt when the reflected light intensity changes significantly to determine the dielectric layer.

第5頁五、發明說明（3) · ·' 的研磨終點’也可以監測CMP製程的正確性。介電層CMP终點監測系統於t拥始偵測，並預定於t終止伯測°利用视窗邏輯（window logic)的原理’於時段^ t内的每個時間點監測一固定視窗19範圍内之曲線斜率的變化情形，當視窗19範園内的曲線斜率變化大於一預定值時’則會產生一輸出訊號來停止CMP製程。如果視窗1 9範圏内的曲線斜率變化始終小於一預定值，則CMP製程會於终止時間點tgi動停止。習知介電層CMP終點監測系統是以視窗邏輯的監測方式’來監測時段△ t内反射光強度對時間曲線之斜率的變化情形’可以決定介電層被完全去除時的研磨终點，也可以用來監測時段△ t内之CMP製程的正確性。但是習知監測方法，並未被用來監測時間點前的一時段△ t内之 CMP製程的狀態，因此當時段△ t内之CMP製程發生錯誤時’操作人員無法即時發現錯誤來停止CMP製程，常會使半導體晶片14#續進行不正確的CMP製程，導致無可挽回的製程錯誤而使半導體晶片報廢，對於半導體產品的良率有很大的影響。因此’本發明之主要目的在於提供一種用來監測CMP 製程狀態的監測方法’可以於時段△ t内監測介電層CMP 製程的狀態’以避免半導髖晶片進行不正球的CMp製程而Page 5 V. Description of the invention (3) · · 'The polishing end point' can also monitor the correctness of the CMP process. The dielectric layer CMP endpoint monitoring system detects at t, and is scheduled to terminate at t. Using the principle of window logic 'monitors a fixed window 19 at each point in time ^ t The change of the slope of the curve. When the change of the slope of the curve in the window 19 is larger than a predetermined value, an output signal will be generated to stop the CMP process. If the change in the slope of the curve within the range of window 19 is always less than a predetermined value, the CMP process will stop at the end time point tgi. It is known that the dielectric layer CMP endpoint monitoring system uses a window logic monitoring method to 'monitor the change in the slope of the reflected light intensity versus the time curve within the time period Δt'. It can be used to monitor the correctness of the CMP process during the time period Δt. However, the conventional monitoring method is not used to monitor the status of the CMP process within a time period Δt before the time point. Therefore, when an error occurs in the CMP process within the time period Δt, the operator cannot immediately detect an error to stop the CMP process. It often causes the semiconductor wafer 14 # to continue an incorrect CMP process, which leads to irreparable process errors and scraps the semiconductor wafer, which has a great impact on the yield of semiconductor products. Therefore, ‘the main object of the present invention is to provide a monitoring method for monitoring the state of the CMP process’, which can monitor the state of the CMP process of the dielectric layer within the time period Δt ’to avoid the semi-conductor hip wafer from performing the erroneous CMp process.

第6頁五、發明說明（4) 降低半導體產品的良率。圈示之簡單說明圈一為習知介電層CMP終點監測系統之監測方法的示意圖。圖二與圈二為本發明用來監測CMP製程狀態的整測方法之示意圈。圈四與圈五為本發明監測方法另一實施例之示意圖。圖示之符號說明 20、30半導體晶片 22介電層請參考圖二與圖三’圖二與圖三為本發明用來監測 CMP製程狀態的監測方法之示意圈。本發明監測方法是用來監測一半導艘晶片20於一時段Δΐΐ内進行一 CMP製程時的狀態。半導體晶片20包含有一介電層22設於半導體晶片 2 0表面上，CMP製程是於習知研磨機台進行，其包含有一具有一孔洞的研磨墊，以向下觸壓半導體晶片表面的介電層22並對其進行機械研磨至一預定厚度。本發明監測方法是於開始進行CMP製程後之時段△ t内，經由研磨墊上的孔洞，以一固定波長之雷射光源由一預定之傾斜角度α照射半導艚晶片2 0表面之介電層22，以產生與α相對應之反射角度之一反射光。於時段△ t内依據一預定之取樣頻率’將每個時間點所監測到的反射光強度記錄下來，使所Page 6 5. Description of the invention (4) Reduce the yield of semiconductor products. Brief Description of the Circles Circle 1 is the schematic diagram of the conventional monitoring method of the dielectric layer CMP endpoint monitoring system. Figures 2 and 2 are schematic circles of the whole measurement method for monitoring the CMP process status according to the present invention. Circle four and circle five are schematic diagrams of another embodiment of the monitoring method of the present invention. Symbols shown in the figure 20, 30 semiconductor wafers 22 Dielectric layer Please refer to Fig. 2 and Fig. 3 'Fig. 2 and Fig. 3 are schematic circles of the monitoring method for monitoring the CMP process status of the present invention. The monitoring method of the present invention is used to monitor the state of a half of the navigating wafer 20 during a CMP process within a time period Δΐΐ. The semiconductor wafer 20 includes a dielectric layer 22 provided on the surface of the semiconductor wafer 20. The CMP process is performed on a conventional polishing machine. The CMP process includes a polishing pad having a hole to press the dielectric on the surface of the semiconductor wafer downward. The layer 22 is mechanically ground to a predetermined thickness. In the monitoring method of the present invention, the dielectric layer on the surface of the semiconductor chip 20 is irradiated with a predetermined inclination angle α through a hole in the polishing pad within a period Δt after the CMP process is started through a hole on the polishing pad. 22. Reflect light at one of the reflection angles corresponding to α. Record the intensity of the reflected light monitored at each time point according to a predetermined sampling frequency within the time period Δt, so that all

五、發明說明（5) 記錄的資料形成一反射光強度對時間的曲線’以整測介電 -層2 2的研磨狀態° 如圈二所示，依據光學原理’在時段△ t内’半導體晶片20表面於一正碟的CMP製程中所產生的反射光強度I包含有一自介電層2 2表面Α»反射之反射光強度IA，以及一自介電層2 2表面B點反射之反射光強度IB。而且光線經由A 點入射至半導醴晶片20表面之C點’再反射到B點，會形成一相位角差0。經過光學原理推算後’反射光強度I的變化規則為 I = Ia+Ib+2(Ia*Ib)1/2c〇s(0 )..........................(1)丨因此隨著介電層22厚度逐漸變薄，反射光強度I會產生一週期性的規則變化’使反射光強度對時間的曲線形成一近似於餘弦函數之曲線。如圈三所示’△ t為前述餘弦函數之一週期。本發明監測方法是於時段△ t内之時段△ t杓，監測並記錄反射光強度I，並依照所記錄的資料來計算反射光強度I之週期性變化規則。當時段△ t内之一起始時段△ t/9所記錄的反射光強度I變化形成一量測曲線MN時，可以依據量測曲線MN來推測下一時段△ t内之曲線變化，也就是一理論曲線NP。随後於時段△ t内持續監測反射光強度I，並計算各時間點之反射光強度I變化的情形，以於時段△ t朽形成一量測曲線Ν’ P’ ’用來與理綸曲線NP的變化做比較。V. Description of the invention (5) The recorded data forms a curve of reflected light intensity versus time 'to measure the grinding state of the dielectric-layer 2 2 ° As shown in circle 2, according to the optical principle' in the time period Δt 'the semiconductor The reflected light intensity I generated on the surface of the wafer 20 during the CMP process of a positive disc includes a reflected light intensity IA reflected from the dielectric layer 2 2 surface A », and a reflection reflected from point B of the dielectric layer 22 surface B. Light intensity IB. In addition, the light is incident on point C 'on the surface of the semiconductor wafer 20 through point A and then reflected to point B, and a phase angle difference of 0 will be formed. After calculation by the optical principle, the change rule of the reflected light intensity I is I = Ia + Ib + 2 (Ia * Ib) 1 / 2c〇s (0) ...... .......... (1) 丨 As the thickness of the dielectric layer 22 gradually becomes thinner, the reflected light intensity I will produce a periodic regular change ', so that the curve of the reflected light intensity versus time forms an approximation The curve of the cosine function. As shown in circle three, 'Δt is a period of the aforementioned cosine function. In the monitoring method of the present invention, the reflected light intensity I is monitored and recorded during a period Δt 杓 within the time period Δt, and a periodic change rule of the reflected light intensity I is calculated according to the recorded data. When a change in the reflected light intensity I recorded in a start period Δt / 9 within a period Δt forms a measurement curve MN, the curve change in the next period Δt can be inferred based on the measurement curve MN, that is, a Theoretical curve NP. Subsequently, the reflected light intensity I is continuously monitored during the time period Δt, and the change of the reflected light intensity I at each time point is calculated, so that a measurement curve N ′ P ′ 'is formed at the time period Δt to be used with the Rylon curve Compare changes in NP.

第8頁五、發明說明（6) 五、發明說明（6) 差位相的 P N 線曲論 ?·ι 理與 ρ ο r標線指曲的測否量與較確比正例磨施研實量本測為做關於量測曲線Ν’ P’的相位差的計算方法如下：假設反射光強度I與相位差0嚴格遵守方程式（1)，若IA、I為已知，則測得了 I，就可以推算得到目前的相位差0。在時段△ t式内，即董測曲線ΜΝ中，已量測了一個反射光強度I的最大值，紀錄為IBax，（0 ITT，m = 0， 2，Page 8 V. Description of the invention (6) V. Description of the invention (6) Theory of PN line curve of difference phase The measurement method is to calculate the phase difference of the measurement curve N'P 'as follows: Assume that the reflected light intensity I and the phase difference 0 strictly follow equation (1). If IA and I are known, then I is measured. You can calculate the current phase difference 0. In the period Δt formula, that is, in the measurement curve MN, a maximum value of the reflected light intensity I has been measured and recorded as IBax, (0 ITT, m = 0, 2,

4，......），貝丨J Ιβ8Χ=Ια+Ιβ+2(Ια*Ιβ)1/2..............................(2) 和一個最小值紀錄為I nin’ （0 =η7Γ，η = 1， 3， 5，......），則 IBin=lA+IB-2(IA*IB)1/2..............................(3) 假設下一個時段△ t 5(半個週期）的曲線的最大值與最小值與時段A t f樣。則時間點t (N點後又過△ t時間）之量測曲線的相位差0 Dt的計算，可經由方程式（4 )得到：4, ...), J 丨 β8 × = Ια + Ιβ + 2 (Ια * Ιβ) 1/2 ............ ........ (2) and a minimum record is I nin '(0 = η7Γ, η = 1, 3, 5, ...), then Ibin = lA + IB-2 ( IA * IB) 1/2 .............. (3) Suppose the next period △ t 5 (half Period) The maximum and minimum values of the curve are the same as the period A tf. Then the calculation of the phase difference 0 Dt of the measurement curve at the time point t (the time Δ t passes after N points) can be obtained by equation (4):

Ut = IΑ+Ι β+2( I A*I b) 1/2c〇s(0 Δΐ)...................(4) 其中 I A+ I B= ( I raax+ I min) / 2 (IA*lB)1/2=(IBax-IBin)/4 於是 4 Δί=〇〇5-1((4ΙΔί-2(Ι eax+ I Bin) ) / (I 屋ax- I Bin))，Ut = IΑ + Ι β + 2 (IA * I b) 1 / 2c〇s (0 Δΐ) ...... (4) where I A + IB = (I raax + I min) / 2 (IA * lB) 1/2 = (IBax-IBin) / 4 Then 4 Δί = 〇〇5-1 ((4ΙΔί-2 (Ι eax + I Bin)) / (I 屋 ax -I Bin)),

〇<0 At <7T 而時間點t在理論曲線NP上的相位差0 Δ t,th可由方程式〇 < 0 At < 7T and the phase difference of time point t on the theoretical curve NP 0 Δ t, th can be calculated by the equation

五、發明說明（7) (5 )得到： φ Δ t.th *Δ t/Δ t ......................(5) 故兩相比較即可得到差值。若定義t # 0 μ•之·相位角偏差值為Δ 0 ’由△必的大小即可當作測量研磨正不正確的指標。故每當經過二次極值點之後就更新I邮與I η妁值’並重新計算下個半週期的曲線。V. Description of the invention (7) (5): φ Δ t.th * Δ t / Δ t ............ (5) Therefore two Compare to get the difference. If t # 0 μ is defined, the phase angle deviation value Δ 0 ′ can be regarded as an index to measure whether the grinding is incorrect or not. Therefore, whenever the second extreme point is passed, the I-post and I η 妁 values' are updated and the curve of the next half cycle is recalculated.

當量測曲線督N與理論曲線NP之相對應各時間點的相位角偏差量△《’皆小於一可預測之相位誤差π /1〇範圍内時’表示半導想晶片20於時段△ t内仍進行正確的CMP製程’則可以依據董測曲線N，P，來推測下一時段内之理論曲線。然後持續以相同的方法，來監測量測曲線舆理論曲線之相位角偏差量。直到量測出的反射光強度變化不符合所推測的理論曲線’表示半導體晶片20進行不正確的CMP製程，便會產生一輪出訊號來停止CMP製程，以避免半導體晶片20持續進行不正確的CMP製程。本發明監測方法是於時段△ t内，藉由反射光強度所產生之週期性的規則變化，以計算理論曲線與量測曲線的相位角差，來監測半導髖晶片20之介電層2¾研磨的狀態。因此時段△ t内，倘若人為操作失誤或其他原因而進行不正確的CMP製程時，本發明監測方法可以即時地產生輸出訊號來停止不正確的CMP製程。When the phase angle deviations at each time point corresponding to the measurement curve N and the theoretical curve NP are △ "'all less than a predictable phase error π / 10 range', it means that the semiconducting chip 20 is in the period △ t If the correct CMP process is still performed within the period, the theoretical curve in the next period can be inferred based on the measurement curves N and P. Then continue to monitor the phase angle deviation of the measured curve and theoretical curve in the same way. Until the measured change in reflected light intensity does not conform to the speculative theoretical curve, it indicates that the semiconductor wafer 20 is performing an incorrect CMP process, and a round of signals will be generated to stop the CMP process to prevent the semiconductor wafer 20 from continuously performing an incorrect CMP. Process. In the monitoring method of the present invention, the dielectric layer 2 of the semiconducting hip chip 20 is monitored by calculating the phase angle difference between the theoretical curve and the measurement curve through a periodic regular change in the intensity of the reflected light during the period Δt. The state of grinding. Therefore, during the period Δt, if an incorrect CMP process is performed by a human due to an operation error or other reasons, the monitoring method of the present invention can immediately generate an output signal to stop the incorrect CMP process.

第10頁五、發明說明（8) 請參考圖四及圈五，圖四及圖五為本發明監測方法另一實施例的示意圈。本發明監測方法可以使用於研磨兩種介電材料層的CMP製程。半導體晶片30包含有一第一介電層3 2設於半導體晶片30之表面上，以及一第二介電層3 4設於第一介電層32表面上，而CMP製程是用來研磨半導髋晶 # 3 0表面’以依序去除第二介電層3 4與第一介電層32。本發明監測方法可用來監測第二介電層34的研磨狀態，並適時提醒操作人員更改相關製程參數，然後繼續監測第一介電層32的研磨狀態。在進行半導艟晶片30的CMP製程時，使用本發明監測方法於一預定時段Δ t内監測第二介電層 34的研磨狀態’並配合習知視窗邏輯的監測方式，於一預定時段△ t卉決定第二介電層34之CMP研磨終點，以適時提醒操作人員更改相關製程參數來進行第一介電層之CMp 製程。於第一介電層進行CMp製程後之一預定時段△ % 内’則可以再使用本發明監測方法，來監測第一介電層3 2 的研磨狀態。因此彈性使用本發明與習知監測方法，可以監測半導趙晶片30兩種介電材料層32、34之CMP製程的狀態’以於製程發生錯誤時即時產生輸出訊號來停止確的CMP製程。相較於習知監測方法，本發明用來監測化學機械研磨製程狀態的監測方法，是於半導髖晶片2〇開始進行CMp製程後之一預定時段At内，以固定波長之光源由一預定之角度照射半導《晶片20表面之介電層22以產生一反射光。Page 10 V. Description of the invention (8) Please refer to Figures 4 and 5, which are schematic circles of another embodiment of the monitoring method of the present invention. The monitoring method of the present invention can be used in a CMP process for polishing two dielectric material layers. The semiconductor wafer 30 includes a first dielectric layer 32 on the surface of the semiconductor wafer 30, and a second dielectric layer 34 on the surface of the first dielectric layer 32. The CMP process is used to polish the semiconductor The hip crystal # 3 0 surface 'sequentially removes the second dielectric layer 34 and the first dielectric layer 32. The monitoring method of the present invention can be used to monitor the grinding state of the second dielectric layer 34, prompt the operator to change the relevant process parameters, and then continue to monitor the grinding state of the first dielectric layer 32. When the CMP process of the semiconductor wafer 30 is performed, the monitoring method of the present invention is used to monitor the polishing state of the second dielectric layer 34 within a predetermined period Δt and cooperate with a conventional window logic monitoring method at a predetermined period △ t Hui decides the CMP polishing end point of the second dielectric layer 34 to prompt the operator to change the relevant process parameters in time to perform the CMP process of the first dielectric layer. Within a predetermined time period Δ% after the CMP process is performed on the first dielectric layer, the monitoring method of the present invention can be used to monitor the grinding state of the first dielectric layer 3 2. Therefore, the present invention and the conventional monitoring method can be flexibly used to monitor the state of the CMP process of the two dielectric material layers 32 and 34 of the semiconductor wafer 30 to generate an output signal immediately when a process error occurs to stop the accurate CMP process. Compared with the conventional monitoring method, the monitoring method for monitoring the state of the chemical mechanical polishing process of the present invention is to use a predetermined wavelength of light source at a predetermined time period At within a predetermined time period At after the semiconducting hip wafer 20 starts the CMP process. The dielectric layer 22 on the surface of the semiconductor 20 is illuminated at an angle to generate a reflected light.

.ΜΗ HH 一 ____________ 第11頁五、發明說明（9) 然後藉由監測預定時段△t内之一起始時段△t乃之反射光強度，並依此而計算反射光之遇期性變化規則，來製作理論曲線與量測曲線。當董測曲線不符合理論曲線之遇期性變化規則時’則產生輸出訊號來停止CMP製程。因此本發明監測方法可以敏銳地監測半導體晶片20之介電層2激研磨的狀態’以於製程發生錯誤時即時地產生輸出訊號來停止不正確之CMP製程，進而提昇半導體產品的良率。以上所述僅為本發明之較佳實施例，凡依本專利範圍所做之均等變化與修飾，皆應屬本發明月甲謂蓋範圍。 I利之涵.ΜΗ HH One ____________ Page 11 5. Description of the Invention (9) Then, by monitoring the intensity of the reflected light at a starting period △ t within a predetermined period △ t, and calculating the change rule of the periodicity of the reflected light based on this To make a theoretical curve and a measurement curve. When the monitoring curve does not meet the rules of the periodic change of the theoretical curve, an output signal is generated to stop the CMP process. Therefore, the monitoring method of the present invention can sharply monitor the state of the dielectric layer 2's polishing of the semiconductor wafer 20 'in order to immediately generate an output signal when a process error occurs to stop the incorrect CMP process, thereby improving the yield of the semiconductor product. The above description is only a preferred embodiment of the present invention, and any equivalent changes and modifications made in accordance with the scope of this patent should fall within the scope of the present invention. The meaning of I

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Claims

六、申請專利範圍 1. 一種監測方法’用來整測一半導體晶片於進行一化學機械研磨製程時之狀態，其中該化學機械研磨製程係用來研磨該半導艟晶片表面之一介電層，該監測方法包含有：於開始進行該化學機械研磨製程後之一預定時段内，以一固定波長之光源由一預定之角度照射該半導艎晶片表面之介電層以產生一反射光’其中該預定時段内所產生之反射光強度於一正確的化學機械研磨製程中會因為該介電層之厚度逐漸變薄而產生一週期性之規則變化；監測該反射光於該預定時段内之一起始時段内之強度並依此而計算該反射光之週期性變化規則；以及於該起始時段後，依據該反射光之週期性變化規則持續監測該反射光之強度直到該預定時段結束為止，若該反射光之強度變化不符合該反射光之週期性變化規則，則產生一輪出訊號》 2·如申請專利範圍第1項之監測方法，其中該輸出訊號係用來停止該化學機械研磨製程。 3·如申請專利範圍第1項之監測方法，其中該光源係由一預定之傾斜角度來照射該半導髏晶片表面之介電層，而該光源之反射光則係由與該傾斜角度相對應之反射角度來進行監測。 4.如申請專利範圍第1項之監測方法，其中在監測該反射光於該預定時段内之一起始時段内之強度變化時，該反射光於該起始時段内之強度係依據一預定之取樣頻率來加以記錄，而該反射光之週期性變化規則則係依據該起始時6. Scope of Patent Application 1. A monitoring method 'for measuring the state of a semiconductor wafer during a chemical mechanical polishing process, wherein the chemical mechanical polishing process is used to polish a dielectric layer on the surface of the semiconductor wafer The monitoring method includes: irradiating a dielectric layer on the surface of the semiconductor wafer with a light source at a predetermined angle within a predetermined period of time after starting the chemical mechanical polishing process to generate a reflected light ' The intensity of the reflected light generated during the predetermined period will cause a periodic regular change due to the gradual thinning of the thickness of the dielectric layer in a correct chemical mechanical polishing process; monitor the reflected light during the predetermined period. The intensity of a reflected period of time is used to calculate the periodic change rule of the reflected light; and after the initial period, the intensity of the reflected light is continuously monitored according to the periodic change rule of the reflected light until the end of the predetermined period If the intensity change of the reflected light does not conform to the periodic change rule of the reflected light, a round of output signals will be generated. 2 · 如The monitoring method of the scope of patent application No. 1 wherein the output signal is used to stop the chemical mechanical polishing process. 3. The monitoring method according to item 1 of the scope of patent application, wherein the light source is irradiated with the dielectric layer on the surface of the semiconductor wafer from a predetermined tilt angle, and the reflected light of the light source is corresponding to the tilt angle Angle of reflection to monitor. 4. The monitoring method according to item 1 of the scope of patent application, wherein when monitoring the intensity change of the reflected light in a starting period within the predetermined period, the intensity of the reflected light in the starting period is based on a predetermined Sampling frequency to record, and the periodic change rule of the reflected light is based on the starting time

第13頁六、申請專利範固 .一~Γ 段内所記錄之強度資料來加以計算。 ^ ^申請專利範圍第1項之監測方法，其中該光源係為一具·有一固定波長之雷射光源。Page 13 VI. Patent Application Fan Gu. The intensity data recorded in paragraphs 1 ~ Γ are used for calculation. ^ ^ The monitoring method of the scope of patent application No. 1 wherein the light source is a laser light source with a fixed wavelength.

6. 如申請專利範圍第1項之監測方法，其中該預定時段 2所產生之反射光強度於一正確的化學機械研磨製程中之遇期性的規則變化係近似於一餘弦函數之曲線。 7. 如申請專利範圍第6項之監測方法，其中該預定時段之時間長為該餘弦函數之一週期時間，而預定時段内之相對應各點之反射光強度的變化係小於一可預測之相位誤差範困内。〇6. The monitoring method according to item 1 of the scope of patent application, wherein the regular change in the periodicity of the reflected light intensity generated during the predetermined period 2 in a correct chemical mechanical polishing process is approximately a curve of a cosine function. 7. For the monitoring method in the sixth scope of the patent application, wherein the time of the predetermined period is a cycle time of the cosine function, and the change of the reflected light intensity at each point within the predetermined period is less than a predictable Phase error range is trapped. 〇

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