494233 五、發明說明（1) (一） 發明背景 熱傳導感測器（Thermal Conductivity Detector 簡 稱TCD )係利用不同氣体熱導係數的差異，來進行感測工 作/熱傳導感測器通常設計成惠式電橋（Wheatstone bridge )’電橋之電阻通以電流加熱至某一特定溫度。當 應用，氣相層析儀時，電橋上有兩股氣体通道，一股欲量 乳體通過一組電阻；另一股參考氣體（即載氣）通過另 一組電阻。當載氣内有其他氣体存在時，其整体的熱導性 質t會改變’使得通過加熱導線的載氣所能移去的熱量發 生ΐ化二進而改變加熱導線的溫度及其電阻，並經由惠式 I仏的，路獲得感測訊號。熱傳導感測主要應用於氣体流 重、真空量_及氣体感測，前兩者係量測相同組成之氣 体’而後者則量測不同組成之氣体。量測真空度時，氣体 分子t t均目由徑須大於真空計之容器；而量測不同氣体 的成份時’其平均自由徑則遠小於感測器，—般均在大氣 壓力下進行。 ^隨著微氣相層析儀的發展，微熱傳導感測器的設計不 外乎有兩種’分別如圖1、2所示。圖1之設計為氣體占1 或2進入流道’從另一端1 /或2’出去，導熱線則位於流 道下方’ 31、3 2分別為熱傳導感測器的上、下蓋，由矽晶 片t異向姓刻製成，控制在恆定的溫度。3為加熱導線，4 為加熱導線之基材’為減少散熱之現象，基材均以薄膜形 式存在。圖1之設計有如下缺點：導熱線之有效散熱面只494233 V. Description of the invention (1) (1) Background of the invention The Thermal Conductivity Detector (TCD) uses the difference in the thermal conductivity of different gases to perform the sensing work. The thermal conductivity sensor is usually designed as a benefit type electric Bridge (Wheatstone bridge) The resistance of the bridge is heated to a certain temperature by electric current. When applied to a gas chromatograph, there are two gas channels on the bridge. One volume of milk passes through one set of resistors; the other reference gas (ie, carrier gas) passes through another set of resistors. When other gases are present in the carrier gas, its overall thermal conductivity, t, will change, so that the amount of heat that can be removed by the carrier gas through the heating wire is reduced to two, thereby changing the temperature of the heating wire and its electrical resistance. If I type, the sensor signal is obtained. Thermal conduction sensing is mainly used for gas flow weight, vacuum volume, and gas sensing. The former two are used to measure gas with the same composition, and the latter is used to measure gases with different compositions. When measuring the degree of vacuum, the gas molecules t t must be larger than the container of the vacuum gauge; and when measuring the composition of different gases, the average free diameter is much smaller than that of the sensor, which is generally performed under atmospheric pressure. ^ With the development of micro gas chromatographs, there are two more designs of micro-thermal conductivity sensors' shown in Figures 1 and 2, respectively. The design of Figure 1 is that the gas occupies 1 or 2 and enters the flow path 'from the other end 1 / or 2', and the heat conducting wire is located below the flow path. ' The wafer t is engraved and controlled at a constant temperature. 3 is the heating wire, 4 is the base material of the heating wire. 'In order to reduce the phenomenon of heat dissipation, the base materials are all in the form of a thin film. The design of Figure 1 has the following disadvantages: The effective heat dissipation surface of the thermal conductor is only
494233 五、發明說明（2) 熱面V、有氣體通過之一面，另一面之散熱則未知，靈敏度 不高。圖2之設計係根據圖一之缺點加以改善，將導熱線 下方姓刻成空穴，使導熱線之有效散熱面成為雙面。圖2 之5又什雖補償了圖一設計之缺失，然此種設計仍有其缺 失，如滯留在電阻線下空穴之氣体不易流通，所殘留之氣 体必影響下一次之量測。針對上述兩種設計之缺失，本創 作作综合性的改善，將熱導線設計成懸掛於流道中央，使 熱導線上下方皆可散熱，玎提高靈敏度且不會有殘留氣体 滯留之問題。 (二）發明目的 解決現有熱傳導感測器靈敏度低及容易有殘留氣体滯 留之問題’以符合微氣相層析儀感測之特性。 彳 (二）發明特性 以微機電加二技術將熱導線製作成懸掛於流道中央， 使熱導線的上下方皆因氣体流經而散熱，可提異感測器靈 敏度且不會造成殘留氣体滯留之問題。 (三）發明内容 本創作所提出之熱傳導感測器設計構想如圖3所示，其 中I,與2分别為參考氣体流道及樣品氣体流道入口，^ 與2則為其出口 ，氣体由一端輸入另一端輸出。3—i、 3-2、3-3、3-4為懸掛式熱導線，分別作為惠式電橋上的 四個電阻，熱導線的上下兩面均有氣体通道。n、12、 Μ 14、15、16、17、18 為八個導線塾（Bonding Pad )’供打金線用，分別作為電源輸入、輸出及讀取訊號494233 V. Description of the invention (2) The hot surface V, where gas passes through one surface, the heat dissipation on the other surface is unknown, and the sensitivity is not high. The design of Fig. 2 is improved according to the disadvantages of Fig. 1. The last name under the heat conducting wire is engraved as a cavity, so that the effective heat dissipation surface of the heat conducting wire becomes double-sided. Although Figure 2-5 compensates for the lack of the design of Figure 1, this design still has its shortcomings. If the gas trapped under the resistance line is not easy to circulate, the remaining gas will affect the next measurement. In view of the lack of the above two designs, this creation is a comprehensive improvement. The hot wire is designed to be suspended in the center of the flow channel, so that the upper and lower sides of the hot wire can dissipate heat, which improves the sensitivity and does not have the problem of residual gas retention. (II) Purpose of the invention The problems of low sensitivity and residual gas retention of existing thermal conductivity sensors are solved to meet the characteristics of micro gas chromatography.二 (II) Characteristics of the invention The micro-electromechanical plus two technology is used to make the hot wire suspended in the center of the flow channel, so that the upper and lower sides of the hot wire are dissipated due to the flow of gas, which can improve the sensitivity of the sensor without causing residual gas The problem of stranding. (3) Summary of the Invention The design concept of the heat transfer sensor proposed in this creation is shown in Figure 3, where I, and 2 are the inlets of the reference gas flow path and the sample gas flow path, respectively, and ^ and 2 are their outlets. One end inputs and the other end outputs. 3-i, 3-2, 3-3, and 3-4 are hanging hot wires, which are respectively used as four resistors on the Hui-type bridge, and the upper and lower sides of the hot wires have gas channels. n, 12, Μ 14,15,16,17,18 are eight wires B (Bonding Pad) 'for gold wire, which are used as power input, output and read signal
D:\micro_gc\micro-gc\專利3. ptd 第5頁 494233 五、發明說明（3) 用。21、22、23、24分別為四個毛細管接頭介面，供氣体 輸入及輸出。圖4為毛細管接頭設計橫戴面圖（沿圖3 aa/ 截面），其中31、3 2分別為熱傳導感測器的上、下蓋 晶片經異向蝕刻製成，4為熱導線3之基材，—般為絕缘且 導熱係數較低is%、pyrex或8认，35為外接毛細 管，3 4為紫外光硬化之環氧樹脂。a 了防止樣品氣体從 較大口徑的毛細管35，進入較小尺寸的流道入口 2會 產生紊流，毛細管接頭以設計成接近流線形為宜以避免 感測到的訊號變差。由於採用異向蝕刻，s i (丨丨i )面的 蝕刻速率很慢，會與Sl (1〇〇)面自然形成夾角“以度的 钟面，可有效降低氣体紊流之現象。圖5為本創作之熱傳 導感測器柄截面圖（沿圖3 b - l/截面），可明顯的看出其主 妥之架構為3丨上蓋、32下蓋及4#導線支撐薄膜所構成。 圖6為電阻線設計示意圖，為有效利用流道中央狹小面 積:，電阻線設計成蛇形來回數次，以拉長導線長度並加大 電阻值。支撐基材則蝕刻成網狀，以利氣體上下流通。圖 7為製造流程圖’（a )為在S i晶d上濺鍍一層絕熱薄膜（b ) 為利用微影光刻及蝕刻技術，將絕熱薄膜製作成所需要的 圖案，（c)為利用KOH、EDP等異向蝕刻液，將絕熱薄膜下 方的矽#成空穴作為氣体通道，而原有之絕熱薄膜正妤懸 掛於空穴的上方，（d)為在絕熱薄膜上蒸鍍熱導線，（e)將 (d)與預先姓刻妤的上蓋利用陽極接合方式結合，以形成，完 整之熱傳導感測器結構。D: \ micro_gc \ micro-gc \ patent 3. ptd page 5 494233 5. Description of invention (3). 21, 22, 23, 24 are four capillary connector interfaces for gas input and output. Figure 4 is a cross-sectional view of the capillary connector design (along the aa / section in Figure 3), where 31 and 32 are the top and bottom wafers of the thermal conductivity sensor, respectively, and the substrate is made of anisotropic etching. 4 is the base of the thermal wire 3. Materials are generally insulated and have low thermal conductivity is%, pyrex, or 8mm, 35 is an external capillary, and 34 is an ultraviolet-curing epoxy resin. a In order to prevent sample gas from entering the smaller-sized capillary inlet 35 from the larger-diameter capillary 35, turbulence will be generated. It is better to design the capillary connector to be more streamlined to avoid the sensed signal from deteriorating. Due to the use of anisotropic etching, the etch rate of the si (丨 丨 i) plane is very slow, and it will naturally form a clock face with an angle "in degrees" with the Sl (100) plane, which can effectively reduce the phenomenon of gas turbulence. Figure 5 shows The cross-sectional view of the heat-conducting sensor handle of this creation (along the section in Fig. 3 b-l /), it can be clearly seen that the main structure is composed of 3 丨 upper cover, 32 lower cover and 4 # wire support film. Figure 6 Design the schematic diagram of the resistance line, in order to effectively use the small area in the center of the flow channel: The resistance line is designed to snake back and forth several times to lengthen the length of the wire and increase the resistance value. The supporting substrate is etched into a mesh to facilitate gas up and down Fig. 7 is a manufacturing flow chart '(a) is a layer of thermal insulation film sputtered on Si crystal d (b) In order to use the photolithography and etching technology to make the thermal insulation film into the required pattern, (c) In order to use an anisotropic etching solution such as KOH and EDP, the silicon # under the heat-insulating film is used as a gas channel, and the original heat-insulating film is hanging above the holes. (D) is vapor deposition on the heat-insulating film. Hot wire, (e) Bonding (d) with the upper cover engraved with the last name by anodic bonding Close to form a complete heat-conducting sensor structure.
D:\micro-gc\micro-gc\專利 3. ptd 第6頁 494233 五、發明說明（4) 圖式說明· 圖1 :現有熱傳導感測器設計之一 圖2，現有熱傳導感測器設計之二 圖3 :本創作之熱傳導感測器設計示意圖 圖4 :熱傳導感測器毛細管接頭橫截面設計示意圖 圖5 :熱傳導感測器橫截面示意圖 圖6 :熱傳導感測器電阻線設計示意圖 圖7 ·本創作之製造流程不意圖 圖號說明： 1 :參考氣体流道八口 1 / :參考氣体流道出口 2 :分析氣体淡道乂口 :分析氣体流道出口 3、3-1、3- 2、3-3、3-4 :金屬導線分別作為惠氏電 橋的四個電阻 4 :絕熱薄膜 11〜1 8 :導線墊 21〜24 :外接毛細管接頭 31 :熱導感測器上盖 32 :熱導感測器下蓋 3 4 :紫外光硬化環氧樹脂 3 5 :外接毛細管 36 :空六D: \ micro-gc \ micro-gc \ patent 3. ptd page 6 494233 V. Description of the invention (4) Schematic illustration · Figure 1: One of the existing thermal conductivity sensor designs Figure 2. The existing thermal conductivity sensor design Figure 2: Schematic diagram of the heat conduction sensor design of this creation. Figure 4: Schematic diagram of the cross section design of the capillary joint of the heat conduction sensor. Figure 5: Schematic diagram of the cross section of the heat conduction sensor. Figure 6: Schematic diagram of the resistance line design of the heat conduction sensor. · The manufacturing process of this creation is not intended to be illustrated by the drawing number: 1: Reference gas flow channel eight outlets 1 /: Reference gas flow channel outlet 2: Analysis gas light channel entrance: Analysis gas flow channel outlet 3, 3-1, 3- 2, 3-3, 3-4: The metal wires are used as the four resistors of the Wyeth bridge. 4: Insulation film 11 ~ 1 8: Wire pads 21 ~ 24: External capillary joint 31: Thermal conductivity sensor cover 32: Thermal conductive sensor lower cover 3 4: UV light hardened epoxy resin 3 5: External capillary 36: Air six
D: Xmicro-gcXmicro-gcX-f-^JS. ptd 第7頁D: Xmicro-gcXmicro-gcX-f- ^ JS. Ptd page 7