TW526578B - Fabrication processes for wafer bonding layer thickness precision control and its non-destructive measurement method - Google Patents

Abstract

A measurement method for silicon wafer thickness thinning is provided. In a silicon wafer substrate, after a check pattern is formed by using an anisotropic chemical etching method, the wafer is polished to a thinner thickness using a polishing machine. The required wafer thickness is achieved after polishing. The above-mentioned check pattern is used to measure and classify the top layer wafer thickness for polishing performance to deal with micro-electrical mechanical process application which requires top wafer thickness with high precision.

Description

526578

First, in the MEMS manufacturing process, thin plates are often used for different applications. The characteristics of micro-electromechanical components such as pressure-sensing elements and co-acceleration sensing elements are 1f; and after two silicon wafers are joined, one of them is further ground t: thin, a thin plate can be formed. For wafer thickness inspection, there are usually two types of inspection methods:

, F One is the detection method using a grinder with a contact altimeter. First, measure the thickness of the wafer by measuring the thickness, calculate the thickness to be removed, and then set the polishing time of the wafer according to the removal rate of the grinder to obtain the required wafer thickness. F Use an altimeter to check whether the wafer thickness reaches the specification. This method 疋 The detection method currently used in the industry, but when performing multiple wafer polishing, the thickness of the wafer itself has a difference of several micrometers to tens of micrometers.

526578 V. Description of the invention (2) Pressure and far distance of grinding p: Early changes will affect the result of grinding. The reason for the above is that the general result of a wafer after grinding is based on the need to obtain a more accurate wafer thickness. Speculation and classification. However, this method is based on the thickness of the upper wafer after thinning. In the early test, the two chips are bonded together. The principle of using non-contact real-time light to contact the material to be tested is the bright signal 1); the other part of the light will also occur when I use a different material. The reflected and transmitted light penetrates the material to be tested (this is the receiving shot, 'two parallel reflections have been detected' / shot 2), the detector is ^ Β Α person 仃 reflection first shot, you can calculate The original material to be tested is thick. This principle: suitable for chemical mechanical polishing (chemicai ST degree ten pairs of a certain layer; material grinding to obtain better flat star 21 method is not suitable for measuring wafer bonding of silicon materials) The thickness of the first layer is thinner. The method of thinning the layer thickness is provided. This method is to provide a single 2 = 2 for the thinning of the Shi Xi wafer bonding. The principle is based on the non-equivalence of the Shi Xi lattice itself ( 〇i〇 (nV oblique fantasy Guangdi 1 picture, in potassium hydroxide (K0Η) solution, Shi Xi (('s rate is much greater than the nightmare i) engraved rate), two% on the side of the wafer έ f and f size inspection patterns, after a certain period of chemical wet etching ^ ^ After the work, different inspections can be etched Depth-measured V-shaped groove, bean γ-type = Inspection® case, as shown in the figure 'Simultaneous Shi Xi (100) and Shi Xi (1⑴ is 54 · 7. The thickness of the upper wafer after grinding can be v-shaped concave If the size of the opening is not measured, the actual thickness of the upper layer wafer is calculated.

The pressure 舛 If is classified. The micro-electromechanical micro-sensing element such as silicon piezoresistive method, such as odometry, etc., is related to the film thickness. The thickness of the upper layer wafer after grinding is classified by using this standard. In this way, " a micro-sensing element with a more uniform output signal size. < Description of previous technology > The measurement of wafer polishing thickness has been mentioned in some previous measurement methods, such as mechanical contact measurement, or optical non-contact measurement, as follows:

, 1) · Republic of China Patent Bulletin No. 3 59, 746, Cai Peiwei's thickness measurement during the wafer back grinding process is a mechanical inspection method. The diamond head probe 21 is in contact with the wafer 20, and the obtained signal is transmitted to the signal sensor in the measuring box 23 using the measuring rod 22 for detection of the total thickness of the wafer. For details, please refer to Figure 2 and reference material [1]. 2) · US Patent No. 6,301,006, Trung T. Doan's thickness measurement in the chemical-mechanical polish process is a non-contact, instant optical inspection method. The wafer 30 is placed in the wafer carrier 31, and the upper detection element module 32 detects the measurement surface on the wafer carrier to measure parameters such as the thickness of the wafer and the polishing rate during the polishing process. Please refer to Figure 3 and reference [2] for the situation.

3) · US Patent No. 6,071,177, C.L. Lin's thickness measurement during the CMP process is a non-contact, real-time optical inspection method for controlling the thickness of silicon dioxide on polished silicon wafers. A light detecting element module 41 is placed under the light-transmissive polishing pad, and the wafer revolves around the center of the polishing pad during polishing. When the wafer 40 passes the light detection element module, the film thickness is measured.

Page 6 526578, description of the invention (4) test. In this case, please refer to Figure 44 and reference material [3]. The grinding method can not measure effectively, and the difference of the characteristics of the sensing element caused by the difference of the chip after receiving the chip is poor. New test method for t-layer silicon B-sheet thickness after monthly grinding. ^ b, smelting a kind of crystal [general summary of the invention] t invention is to provide a new wafer = 4 Shi Xi wafer wafer bonding is prone to crack ^ inspection method. Bonding is performed by wafers. It is necessary to use a thicker process to provide several wafer bonding methods using a page-first process. The wafer bonding # ^ m # inch pattern is then fabricated by wet etching. ;: ¥ -shaped groove check pattern required for weight. degree. This wafer grinding thickness inspection method can be used to measure the thickness of the fine wafer. Therefore, a knife is used to produce a more accurate method. When the subsequent micro-sensor process requires the two dream wafers to be bonded and polished, the grinding thickness inspection method is listed. See below for a detailed description of the preferred embodiment. ,: The following is a preferred implementation of the present invention, which is to implement the two real-world processes: d = inspection = case = by non-bonding with another-wafer. After that, the process of re-grinding the film on the layer i of U, and the first surface of the upper layer: the first and second surface of the soil layer on the surface of the film, and the inspection mark made by the younger surface is used as the research page 7 526578 5 5. Description of the invention (5) ---- The basis for discriminating the grinding thickness · To control the thickness of the silicon substrate after grinding. — The subordinates are not precise, but the production of consistent elements does not necessarily conform to the description. The skilled person can make various changes and modifications without departing from the actual spirit of the present invention. & Solid situation [Example 1] Wafer grinding process inspection flow chart as shown in Figure ^ and Figure "Shixi wafer (the surface has oxide stone or nitride stone or no _th surface, ^ 'in, check Figures 210, 220, 230, and exposure development, the potassium oxide uom solution is anisotropic wet surname engraved oxygen surname into v-shaped grooves m, 221, 231. After that, the above ^ lookup chart ^: surface and other -Silicon wafer 3 (the surface has silicon oxide or silicon nitride or benefit), tianbond bonding (Fusion Bonding) f gX η θ ", the silicon is one wafer earlier, and then the upper wafer is entered. It becomes a wafer, this That is, when the daily v-shaped grooves for the micro-sensing element are manufactured, the grinding of the m-shaped wafer is stopped until the opening, and the width of the opening can be used to say that the surface of Ganyang produces a square-shaped visibility. Different from the remaining fine film selection, the thin layer thickness classifies the wafer to determine the ib, and the inspection flow of the grinding machine is generally used in accordance with the standard; υ: meets the requirements of the specification. And provides-the channel measurement wafer factory r sound: i comparison: the present invention is the thin layer thickness and classification before wafer bonding. sub & clothing, and optical The micro-mirror can detect the 5th figure of the square belt ft invention t 'thickness inspection pattern 210, 220, 23. The two fish two are 28.3 ... 26.9㈣, W _, by Shi Xi (100) and Shi Xi ⑴1) The central angle is 54.7. In the relational formula, from the calculation of 526578 V. Invention description (6), the depth dimensions A, B, and C of the V-shaped grooves 211, 221, and 231 are 20.0, 19.〇 # m, and 18.0 // m. Therefore, the opening of the V-shaped groove is observed by using a microscope and other tools, and the opening size of the V-shaped groove is measured. Based on the geometric relationship of FIG. 6, the remaining thickness of the upper wafer grinding Z = [( WrW2) / 2] tan (54 · 7.). The upper wafers are calculated in this way, and the wafers are classified according to their thicknesses, without the need to use other measuring instruments to measure the wafer thickness. [Embodiment 2] The current micro-electro-mechanical process often requires a silicon sheet as a sensing mechanism, such as a Shixi piezoresistive pressure gauge, which uses a silicon sheet to sense the pressure change, and the thickness of the silicon sheet is used for pressure sensing. Sensitivity has a great impact, so controlling the thickness of the thin plate is very important to the performance of the component. Referring to FIG. 7, the same process as described in Example 1 except that the bottom layer ^ = sheet = 1 has been etched with an inductively coupled plasma ion etching machine (1CP R1E) f, and the groove is etched in the mouth. Subsequent production of bonding and grinding is started to control the thickness of the thin layer I. Therefore, the thickness inspection method of the present invention is firstly used on the crystal 4 ^ 4 (20, 〇, M · 〇 111, 18 · 〇 111) On the upper layer of Shi Xi :. Zhi, and then silicon fusion with the lower layer of the Xi Xi chip that has been engraved. The existing grinding technology thins the upper layer of the wafer, and matches the thickness: inside and outside sides ::: 1 accurate: thin plate thickness, ⑯Thin sheet can be used to sense m. Boundary force only. The thickness of the thin layer in this embodiment is d = 1 8. 0 # As described above, the method of knowing the specifications, ’the new method for detecting the thickness of the upper silicon wafer provided by the present invention does not require the use of complicated auxiliary equipment,

526578 V. Description of the invention

The opening of the v-shaped groove or the size of the opening can be used to calculate the actual thickness of the thin layer to ensure the consistency of the characteristics of the micro-inductive element. The patent of the law ^ It is a virtue to ask for a quasi-patent. ^ # [Reference] [1] Cai Peiwei, Ma Huaren, Li Junjie, Cai Dongtai, Wafer Thickness Measuring Device 〃, Republic of China Patent Gazette Bulletin No. 359746.

[2] Trung T. Doan, '' Endpoint Detector And Method For Measuring A Change In Wafer;

Thickness / 7, United States Patent, Patent Number: 6,301, 006 B1 (2001).

[3] C.L. Lin, Tin Chun Wang, Method And Apparatus For Determining End Point In A Polishing Process ’’, United States Patent, Patent Number: 6, 071, 177 (2000) ·

Page 10. 526578 Brief Description of Drawings Figure 1 is a schematic diagram of a v-shaped groove produced by a non-isotropic etching process on a wafer. -The figure produced after the private clothing is a schematic diagram of the thickness measuring device shown in the Republic of China Patent Bulletin No. 3, No. 746. ⑨ 心 日 曰 The figure of tel is a schematic diagram of the measurement set in the wafer disclosed in US Patent No. 6,301,006. < Intentions of Day to Day, Figure 4 is a diagram showing a polishing apparatus disclosed in U.S. Patent No. 6,0071,177, which is a diagram showing a thickness inspection part of a wafer polishing process according to the present invention. The thickness check pattern of the wafer is applied to the micro-sensing element. [The symbols in the figure are not compared with the component names.] 1: After the silicon wafer is engraved, the pyramid 2 1 0 is ground and exposed on the second surface 210. The layout pattern of the first side of the component: the layout pattern of the first side of the slot element 21 ° via the anisotropic surname 21 2: the first hole of the component 220 · the layout pattern of the first side of the element 221: the element- Surface layout pattern 220 is formed after anisotropic etching

Page 11 526578 V-groove for simple illustration-230: Layout pattern of the first side of the component 2 3 1: Layout pattern of the first side of the component 2 3 0 V-shaped groove formed after anisotropic etching 3 : Silicon wafer A: 2 11 is the depth of the V-shaped groove after anisotropic etching B: 22 1 is the depth of the V-shaped groove after anisotropic etching C: 231 is V-shaped groove after anisotropic etching The depth of the groove Z: the remaining thickness after polishing the silicon wafer Wi: the size of the silicon wafer thickness inspection pattern W2: the polished opening size of the silicon wafer V-groove 401: the lower silicon wafer 402: the thickness inspection pattern 403 of different sizes: Micro-sensing element vacuum chamber 4 0 4 ·· Upper silicon wafer ά: Upper silicon wafer 404 thickness

Claims (1)

526578 6. Scope of patent application1. A method for inspecting the thickness of a thin wafer and a method for inspecting the thickness of a wafer V-shaped recesses are produced on one side of the directional etching / sunday moon; whether the thickness of the fine stone bird is reached during the production of the film is checked by the user / i / 4 a · Provide a silicon wafer substrate, check the thickness of the board, and perform exposure and development: it is to etch several grooves of the above-mentioned layout pattern into a w-groove to perform a non-directional etching process. The upper wafer f-plane and Another-wafer is used for wafer bonding;. On the second side of the upper wafer, a grinding and polishing process is performed. E. Classification according to the thickness of the open-air toilet layer wafer generated on the wafer surface after grinding. As the remaining method Λϋη! The thickness inspection method of the thinning of the wafer in the first item, go to Ding Yi, the size of the openings produced on the wafer surface after grinding, and the thickness of the upper wafer is used as a more accurate thickness classification method. The thickness of the wafer in the first range of the method of the inspection of the thickness of the thin film Fang Gepolo L 1 said h wafer 糸 f lapping, polishing (grindind or polishing (P0i1Shlng) or chemical mechanical polishing (chemicai mechanical polishing) ) Or any combination thereof for thinning. 4. If the thickness inspection method of wafer thinning according to item 1 of the patent application 'wherein', the thickness check pattern can be determined by whether the vertex of the groove is the criterion for whether the grinding is stopped or not. 5 · Thickness inspection method for wafer thinning if the scope of patent application is No.! 526578 10 · The method for inspecting the thickness of wafer thinning according to item 1 of Shen Youyue's patent scope, in which the lower wafer is a Shi Xi wafer. Or a Shi Xi wafer with an oxide stone surface or a Shi Xi with a nitride stone surface. Wafer. Page 14